JP2002107110A - Relative rotational position detector - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform accurate detection even if there is rattling of an input shaft or an output shaft. Provide a detection device with a small and simple structure. Facilitates temperature drift compensation. SOLUTION: A coil part (10) in which an AC-excited coil (L1) is arranged, and a coil part (10) arranged on first and second shafts (2, 3) connected by a torsion bar (1). 1
And a second magnetic responsive member (11, 12), and the relative position of the magnetic responsive member changes according to the relative rotational position, and an output corresponding to this is generated from the coil section (10).
An Oldham mechanism (F1, S1) is provided between the first and second shafts (2, 3) and the first and second magnetic response members (11, 12).
1, S2, F2) are provided to absorb unnecessary movements of the shafts other than the rotation direction so as not to be transmitted to the magnetically responsive members (11, 12).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a coil which is AC-excited, and a pair of magnetic or conductive members which are magnetically coupled to the coil and relatively displaced in rotation. The relative rotational position detecting device is suitable for detecting a relative rotational position such as a twist amount and a rotational displacement of two relatively rotatable axes, and particularly has a rattling of an input shaft or an output shaft. However, it is possible to perform high-precision detection, or to make the device configuration compact, or to use only a primary coil excited by one-phase alternating current to obtain a multi-phase amplitude function characteristic. Generating the output AC signal shown according to the relative rotational position to be detected,
About.

[0002]

2. Description of the Related Art As a method of detecting the amount of twist of two relatively rotatable shafts, it has been conventional to provide a detection device such as a potentiometer or a resolver device on an input shaft and an output shaft connected via a torsion bar. Well-known from When using a potentiometer, a slider is provided on the input shaft and a resistor is provided on the output shaft, so that the contact position of the slider against the resistance changes according to the relative rotational position of the input shaft and the output shaft. Then, an analog voltage corresponding to this is obtained. In the case of using a resolver device, a resolver device is provided on both the input shaft and the output shaft, and a relative rotation amount (torsion amount) is detected based on angle signals from both resolver devices. On the other hand, a non-contact torque sensor for power steering using an induction coil has been developed as a device for detecting a rotational displacement between two relatively rotatable axes. In this case, in order to take out the voltage induced in the induction coil, a resistance element is connected in series with the coil, and the induction voltage is taken out by the voltage dividing ratio between the resistance element and the impedance of the induction coil.

[0003]

In the prior art of the type using a potentiometer, problems of poor contact and failure are always encountered due to the mechanical contact structure. Further, since the impedance of the resistor changes due to the temperature change, the temperature drift compensation must be appropriately performed. On the other hand, in the conventional technology using a resolver device, the resolver device must be provided on both the input shaft and the output shaft that are connected by the torsion bar, so that the entire device becomes larger and costs are reduced. There is a difficulty that it becomes expensive. In addition, a conventional rotational displacement detection device known as a non-contact torque sensor for power steering using an induction coil is configured to measure an analog voltage level generated according to a small rotational displacement, and the detection resolution is not sufficient. Inferior. Further, in order to take out the voltage induced in the induction coil, a resistance element is connected in series with the coil, and the induction voltage is taken out according to a voltage dividing ratio between the resistance element and the impedance of the induction coil. The temperature drift compensation performance is poor due to the difference in temperature characteristics from the resistance element. Furthermore, in the case of a type using a magnetic induction type non-contact sensor including a resolver device, when unnecessary movement other than rotation is applied to the input shaft,
Undesirably distorted arrangement of the coil and the magnetic body in the magnetic induction type sensor causes an error that changes the gap of the magnetic circuit, and it is difficult to detect an accurate amount of twist. For example, a torque sensor of this type is used for a rotating shaft of a steering wheel of an automobile, but in such an application, an unnecessary motion other than rotation is easily added to the input shaft, and thus an improvement is desired. Was.

[0004] The present invention has been made in view of the above points, and an object thereof is to provide a relative rotational position detecting device capable of performing accurate detection even if there is rattling of an input shaft or an output shaft. Is what you do. It is another object of the present invention to provide a relative rotation position detecting device having a small and simple structure. It is another object of the present invention to provide a relative rotation position detection device that can easily compensate for temperature characteristics. It is another object of the present invention to provide a relative rotation position detecting device capable of detecting with high resolution even if the relative rotation displacement of the detection target is minute.

[0005]

According to a first aspect of the present invention, there is provided a relative rotational position detecting device comprising:
A relative rotation position detecting device for detecting a relative rotation position of a second shaft, wherein a coil portion having at least one coil excited by an AC signal is arranged; and a first and second shaft. And a magnetically responsive member disposed magnetically with respect to the coil portion, wherein the first and second magnetic responsive members are magnetically coupled to each other in accordance with the relative rotational position. A position which changes and an output corresponding to the position is generated from the coil portion, at least one of the first and second shafts, and the first and second magnetic responsive members arranged corresponding thereto; And an Oldham mechanism for absorbing unnecessary movement of the shaft other than the rotation direction.

[0006] The Oldham mechanism absorbs unnecessary movement of the shaft other than the rotation direction, so that the first and second shafts are absorbed.
The relative positional relationship of the magnetic responsive members changes only in response to the relative rotational positions of the first and second shafts, and is not affected by other unnecessary movements. For example, the first shaft may be an input shaft, and the Oldham mechanism may be provided between the first shaft and the corresponding first magnetic response member. Since the rotational motion of the first shaft is accurately transmitted to the first magnetic responsive member via the Oldham mechanism,
The relative positions of the first and second magnetically responsive members accurately reflect the relative positions of the first and second axes, so that accurate position detection can be performed without any problem. If the first shaft moves in a direction other than the rotation direction, for example, if the shaft moves in the radial direction due to a slight bending of the shaft, the Oldham mechanism absorbs this movement and the relative position of the first and second magnetic responsive members becomes larger. Does not affect the positional relationship. Therefore, the relative arrangement of the first and second magnetic response members does not distort in conjunction with the bending of the first and second axes (input / output axes),
Undesired fluctuation does not occur in the air gap between the first and second magnetic response members or the air gap between the first and second magnetic response members and the detection coil.
Also, the principle structure of the sensor is that the Oldham mechanism according to the present invention can be applied to any type of sensor that responds to a change in magnetic coupling via an air gap. Has a beneficial effect. Thus, according to the present invention, in the relative relationship between the input shaft and the output shaft, even if undesired play other than the rotation direction occurs,
Accurate detection can be performed.

A relative rotational position detecting device according to a second aspect of the present invention is a relative rotational position detecting device for detecting a relative rotational position of first and second shafts that are relatively rotatable, A coil unit in which one sensor coil excited by an AC signal is arranged; and first and second magnetic response members arranged on the first and second axes, wherein the coil unit is Magnetically coupled to each other, and the relative positions of the first and second magnetic response members change according to the relative rotational position;
The sensor coil generates a corresponding output from the sensor coil, a temperature compensation coil connected in series to the sensor coil, and a connection point between the sensor coil and the temperature compensation coil. And a rectifier circuit for rectifying the output signal and obtaining a DC voltage at a level corresponding to the relative rotational position by rectifying the output signal. In this case, a circuit for generating a predetermined reference voltage composed of an AC signal, an output signal of the sensor coil and the reference voltage are calculated, and an AC output signal having an amplitude coefficient corresponding to the relative rotational position is generated. And a rectifier circuit that inputs an AC output signal of the arithmetic circuit to the rectifier circuit to obtain a DC voltage having a level corresponding to the relative rotational position.

[0008] In the above configuration, the first and second magnetic response members typically include at least one of a magnetic material and a conductor. The degree of magnetic coupling of the first and second magnetic response members to the sensor coil changes according to the relative rotational position of the first and second shafts. First
And when the second magnetic response member is made of a magnetic material,
And as the degree of magnetic coupling of the second magnetic response member to the sensor coil increases, the inductance of the coil increases, and the electrical impedance of the coil increases,
The voltage generated in the coil, that is, the voltage between terminals increases.
Conversely, as the degree of magnetic coupling of the first and second magnetic response members to the sensor coil decreases, the inductance of the coil decreases, and the electrical impedance of the coil decreases. Thus, while the relative rotation position of the first and second magnetic response members with respect to the coil unit changes over a predetermined rotation angle range with the relative rotation of the detection target, the terminal voltage of the coil gradually increases (or increases). Gradually decreasing)
Will change.

Here, by providing a temperature compensating coil connected in series with the sensor coil, the temperature of the sensor coil is changed based on a change in impedance of the sensor coil from a connection point between the sensor coil and the temperature compensating coil. Since the output voltage of the sensor coil is extracted, the temperature drift can be appropriately canceled out by using the same coil, and the output voltage with the temperature drift compensated can be extracted. Further, generating a predetermined reference voltage composed of an AC signal, calculating an output signal of the sensor coil and the reference voltage, and generating an AC output signal having an amplitude coefficient corresponding to the relative rotational position. This means that the amplitude characteristics of the output signal of the sensor coil can be set to desired characteristics. For example, adding or subtracting the reference voltage means that the amplitude characteristic of the output signal of the sensor coil can be offset at a desired level. The AC output signal is rectified by a rectifier circuit to obtain an analog DC voltage having a level corresponding to the relative rotational position. That is, the present invention can be applied effectively when it is desired to obtain a torque detection signal with an analog DC voltage. Then, by the calculation using the reference voltage, control can be performed so as to obtain an analog DC voltage having desired characteristics. Further, by providing the temperature compensation coil connected in series to the sensor coil, temperature drift compensation can be appropriately performed.

A relative rotational position detecting device according to a third aspect of the present invention is a relative rotational position detecting device that detects a relative rotational position of first and second shafts that are relatively rotatable, A coil unit in which at least one coil excited by an AC signal is arranged, and first and second magnetic response members arranged on the first and second shafts, wherein the coil unit is Magnetically coupled, the relative position of the first and second magnetic response members changes according to the relative rotational position, and an output corresponding to the change is generated from the coil unit. The member is a flat plate-shaped member having a plurality of slits formed at predetermined intervals in the rotation direction. That change the coupling Comprises a.

According to the above arrangement, the first and second magnetic responsive members disposed on the first and second shafts respectively have a plurality of slits formed at predetermined intervals in the rotational direction. The magnetic coupling member is characterized in that the magnetic coupling to the coil portion changes according to the degree of overlap of the slit portions of the respective magnetic response members according to the relative rotational position. As a result, the structure of the first and second magnetic response members becomes a flat and compact structure as a whole, and is much simpler, smaller, and more compact than a structure in which large uneven teeth are provided. be able to.

[0012] In the relative position detecting device according to the present invention according to any of the above aspects, the one which is excited by one-phase alternating current can be used.
Using only the next coil (that is, the sensor coil), an output AC signal showing the amplitude function characteristics of a plurality of phases can be generated according to the relative position to be detected. That is, a circuit for generating a predetermined reference voltage composed of an AC signal, an output signal of the coil unit and the reference voltage are calculated, and at least two AC output signals having a predetermined periodic amplitude function as an amplitude coefficient are generated. The circuit may further include a circuit in which the periodic amplitude function of each of the AC output signals differs by a predetermined phase in its periodic characteristic.

[0013] For example, typically, a gradually increasing curve represented by a voltage generated in the coil while the relative position of the pair of magnetically responsive members changes over a predetermined range is from 0 to 90 degrees in the sine function. Can be compared to a function value change in the range of Here, the AC signal component is sinω
Assuming that the amplitude coefficient level value of the sensor coil output voltage Vx obtained corresponding to the start position of the appropriate section in the gradually increasing change curve indicated by t and the voltage between the terminals of the sensor coil is Pa, the start of the section The coil output voltage Vx corresponding to the position is expressed as Pa sin ωt. When the amplitude coefficient level value of the sensor coil output voltage Vx obtained corresponding to the end position of the section is Pb, the sensor coil output voltage corresponding to the end position of the section can be expressed as Pb sinωt. You. Here, the value Pa sinω of the coil output voltage Vx corresponding to the starting position
When an AC voltage having the same value as t is determined as a reference voltage Va and is subtracted from the sensor coil output voltage Vx, an amplitude coefficient of the sensor coil output voltage Vx is represented by a function A (x). A (x) sinωt−Pa sinωt = ｔA (x) −Pa｝ sinωt (1) At the beginning of the section, A (x) = Pa
Therefore, the amplitude coefficient “A (x) −
“Pa” becomes “0”. On the other hand, at the end position of the section, since A (x) = Pb, the amplitude coefficient “A (x) −Pa” of this calculation result is “Pb−Pa”. Therefore, the amplitude coefficient “A (x) −Pa” of the calculation result shows a function characteristic that gradually increases from “0” to “Pb−Pa” within the range of the section. Here, since “Pb−Pa” is the maximum value, if this is equivalently considered as “1”, the amplitude coefficient “A (x) −Pa” of the AC signal according to the above equation (1).
Changes from “0” to “1” within the range of the section, and the function characteristic of the amplitude coefficient is changed to the characteristic of the sine function in the first quadrant (that is, the range of 0 to 90 degrees). Can be compared. Therefore, the amplitude coefficient “A (x) −Pa” of the AC signal according to the above equation (1) can be equivalently expressed as sin θ (however, approximately 0 ° ≦ θ ≦ 90 °).

[0014] In a preferred embodiment, the circuit for generating the predetermined reference voltage generates first and second reference voltages, and the arithmetic circuit includes a voltage extracted from the one coil and the first and second voltages. A first AC output signal having a first amplitude function as an amplitude coefficient by performing predetermined first and second calculations using the second reference voltage;
And a second AC output signal having a second amplitude function as an amplitude coefficient. In this case, since the coil section need only have one sensor coil, the configuration can be simplified to a minimum. The first
By using the above Va as the reference voltage of
Of the sine function can be obtained as an amplitude function having a characteristic substantially in the first quadrant (that is, in the range of 0 to 90 degrees). An AC voltage having the same value as the value Pb sinωt of the coil output voltage Vx corresponding to the end position of the section is determined as a second reference voltage Vb,
When the difference from x is obtained, Vb−Vx = Pb sinωt−A (x) sinωt = ｔPb−A (x)｝ sinωt (2) At the beginning of the section, A (x) = Pa
Therefore, the amplitude coefficient “Pb−A
(x) "becomes" Pb-Pa ". On the other hand, at the end position of the section, since A (x) = Pb, the amplitude coefficient “Pb−A (x)” of this calculation result is “0”.
Therefore, the amplitude coefficient “Pb−A (x)” of the calculation result is obtained.
Indicates a function characteristic that gradually decreases from “Pb−Pa” to “0” within the range of the section. As before,
Assuming that “Pb−Pa” is equivalent to “1”, the amplitude coefficient “Pb−A (x)” of the AC signal according to the above equation (2).
Changes from “1” to “0” within the range of the section, and the function characteristic of the amplitude coefficient is changed to the characteristic of the first quadrant (that is, the range of 0 to 90 degrees) of the cosine function. Can be compared. Therefore, the above equation (2)
The amplitude coefficient “Pb−A (x)” of the AC signal according to the following equation can be equivalently expressed as cos θ (however, approximately 0 ° ≦ θ ≦ 90 °). Note that the subtraction in equation (2) may be “Vx−Vb”.

In this way, only by using one coil and two reference voltages, it is possible to generate two AC output signals each representing an amplitude according to the sine and cosine function characteristics according to the relative rotational position to be detected. For example,
The relative rotational position to be detected is set to a predetermined detectable range of 3
In terms of a phase angle θ when converted to a phase angle of 60 degrees, an AC output signal having an amplitude that exhibits a sine function characteristic can be generally represented by sin θ sinωt, and an amplitude that represents a cosine function characteristic. The AC output signal having the following can be represented by cos θ sin ωt. This is similar to the form of an output signal of a position detector called a resolver, and is extremely useful.
For example, the two AC output signals generated by the arithmetic circuit are input, and a phase value in the sine and cosine functions that defines the amplitude value is detected from a correlation between the amplitude values in the two AC output signals, It is preferable that the apparatus further includes an amplitude / phase converter that generates the position detection data of the detection target based on the detected phase value. Since the sine and cosine functions exhibit characteristics in a range of approximately one quadrant (90 degrees), the detectable position range is detected by being converted into a phase angle in a range of approximately 90 degrees.

When a non-magnetic good conductor (ie, diamagnetic material) such as copper is used as the magnetic response member,
The self-inductance of the coil decreases due to the eddy current loss, and the voltage between the terminals of the coil gradually decreases as the magnetic response member approaches the coil. Also in this case, it is possible to detect in the same manner as described above. As the magnetic response member, a hybrid type in which a magnetic material (that is, a ferromagnetic material) and a nonmagnetic / conductive material (that is, a diamagnetic material) are combined may be used. In another embodiment, the magnetic responsive member may include a permanent magnet, and the coil may include a magnetic core. In this case, the corresponding portion of the magnetic core on the side of the coil becomes magnetically saturated or supersaturated in accordance with the approach of the permanent magnet, and the magnetic responsive member, that is, the terminal of the coil is changed in accordance with the relative displacement of the permanent magnet with respect to the coil. The voltage will gradually decrease.

Thus, according to the preferred embodiment of the present invention, only the primary coil needs to be provided, and the secondary coil is unnecessary, so that it is possible to provide a small and simple structure detecting device. Also, by using one sensor coil, a plurality of AC output signals each representing an amplitude according to a predetermined periodic function characteristic according to a detection target position (for example, two AC output signals each representing an amplitude according to a sine and cosine function characteristic) ) Can be easily generated, and at least approximately 1
A quadrant (90 degrees) can be taken. Therefore, detection can be performed in a relatively wide phase angle range with a small number of coils, and the detection resolution can be improved. Further, even if the displacement of the detection target is minute, relative position detection with high resolution is possible. Further, accurate analog arithmetic operation can be performed in which both the output voltage and the reference voltage are temperature drift compensated, and relative position detection excluding the influence of temperature change can be easily performed. Of course, the circuit for generating the reference voltage is not limited to a coil, and a voltage generation circuit having a suitable configuration such as a resistor may be used. In addition,
The number of coils and reference voltages is not limited to one or two, but may be more. With this, the available phase angle range is not limited to substantially one quadrant (90 degrees), but is further expanded. It is also possible.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, in order to facilitate understanding of the principle of position detection in the embodiment, for convenience of explanation, the first embodiment will be described first.
With reference to FIGS. 1 to 5, a description will be given of a position detecting device having a compact configuration including a flat magnetic response member without an Oldham mechanism. FIG. 1A is an exploded perspective view showing the structure of the relative rotation position detecting device according to the first embodiment, and the cross section of the coil unit 10 is shown. FIG. 1B is a front view showing an embodiment of the overall shape of the flat first magnetic response member 11, and FIG. 2C is a front view of the second flat magnetic response member 12.
FIG. 2 is a front view showing an embodiment of the overall shape of the present invention. FIG. 2 (A)
Is an axial cross-sectional schematic view of the relative rotational position detection device,
Only one half is shown for simplicity of illustration, but the other half appears symmetrically to that shown. FIG. 2B is an electric circuit diagram related to a coil in the device.

The relative rotational position detecting device detects a torsion angle between an input shaft (first shaft) 2 and an output shaft (second shaft) 3 connected via a torsion bar 1. It functions as a torque sensor. Input shaft (1st
The first magnetic responsive member 11 is disposed on the side of the shaft 2), and rotates together with the rotation of the input shaft 2. On the side of the output shaft (first shaft) 3, a second magnetic responsive member 12 is arranged, and rotates together with the rotation of the output shaft 3. The coil unit 10 includes a sensor coil L1 and a temperature compensation coil L2 housed in a ring-shaped magnetic bobbin having an I-shaped (or H-shaped) cross section.
, A pair of magnetic responsive members 11 and 12 is arranged. The role of the temperature compensation coil L2 will be described later. The first and second magnetic response members 11 and 12 are made of a magnetic material such as a disk-shaped iron, and are magnetically coupled to the coil L1. The first and second magnetic responsive members 11 and 12 are plate-shaped members formed with a plurality of slits 11 a and 12 a at predetermined intervals in the rotation direction. Each magnetic response member 1 corresponding to a relative rotational position
The magnetic coupling to the sensor coil L1 changes depending on the degree of overlap between the slits 11a and 12a between the slits 1 and 12. The slits 11a and 12a may simply be formed by an air gap.

As shown in FIG. 1B, the slit portion 11a of the first magnetic response member 11 includes a plurality of rectangular (fan-shaped) slits repeatedly provided at a predetermined pitch P in the circumferential direction. A portion 11b between the slits 11a formed of an air gap is made of a material of the magnetic response member 11, that is, a magnetic material. As shown in FIG. 1C, the slit portion 12a of the second magnetic response member 12 also includes a plurality of slits repeatedly provided at the same predetermined pitch P in the circumferential direction. The portion 12b between the slits 12a is made of a material of the magnetic response member 12, that is, a magnetic material. Each slit part 11a, 12
The size of a is the same. In the embodiment, the second magnetic response member 12 has a shape like a gear, but is not limited thereto, and may have a shape similar to that of the first magnetic response member 11.

The first magnetic response member 11 and the second
And the magnetically responsive member 12 are arranged in a non-contact manner in a non-contact manner, according to the relative rotational position (the amount of twist) between the input shaft 2 and the output shaft 3.
The range of overlap between the magnetic members a and 12a and the magnetic portions 11b and 12b increases or decreases. In other words, one slit hole 11a, 12a is opened and closed by the other magnetic body portion 11b, 12b according to the relative rotational position (torsion amount) between the input shaft 2 and the output shaft 3. . For example, when the two slit holes 11a and 12a are completely displaced and completely closed by the magnetic portions 11b and 12b, the presence of the magnetic material in the magnetic circuit of the sensor coil L1 is maximum (the area of the air gap). Is the minimum), and the magnetic coupling to the sensor coil L1 shows the maximum magnetic permeability. Conversely, both slit holes 11
a, 12a completely overlap each other and the magnetic portions 11b, 12b
When the sensor coil L1 is opened without being completely closed, the presence of a magnetic substance in the magnetic circuit of the sensor coil L1 is minimized (the area of the air gap is maximum), and the magnetic coupling to the sensor coil L1 is minimized. Shows magnetism. This point will be described later in detail with reference to FIG.

On the side opposite to the sensor coil L1,
The auxiliary magnetic responsive member M provided behind the second magnetic responsive member 12 is a plate made of a non-magnetic and highly conductive (diamagnetic) material such as copper. Due to the presence of the non-magnetic and high-conductivity auxiliary magnetic response member M, the slit holes 11 of the first and second magnetic response members 11 and 12 are formed.
In the air gap portion formed by the overlap of a and 12a, a non-magnetic and good conductor (that is, a diamagnetic material) is arranged, and the magnetic permeability in that portion is further reduced by eddy current loss. Therefore, by further reducing the magnetic permeability due to the eddy current loss in the portion where the magnetic permeability decreases, the range of change of the induced voltage in the detection target range can be expanded by the hybrid effect, and the detection resolution is improved. be able to. Instead of providing such a plate-shaped auxiliary magnetic response member M, the slit portions 11a and 12a of the magnetic response members 11 and 12 are not formed as simple air gaps, and a non-magnetic and good conductor is disposed in that portion. You may make it. Of course, if the above-described hybrid effect is not required, the auxiliary magnetic response member M may be omitted.

The input shaft 2 and the output shaft 3 are respectively connected to other mechanical systems (not shown), and the output shaft 3 rotates in conjunction with the rotation of the input shaft 2, and according to the magnitude of the torque. As a result, a twist is generated between the input shaft 2 and the output shaft 3 via the torsion bar 1. This twist causes a rotation error (rotational deviation) between the input shaft 2 and the output shaft 3. For example, when applied to power steering of an automobile, the input shaft 2 is connected to a steering wheel, and the output shaft 3 is connected to a steering gear mechanism.

The sensor coil L1 is excited at a constant voltage or a constant current by a predetermined one-phase AC signal (tentatively represented by sinωt) generated from the AC generator 30. The magnetic field generated from the coil L1 forms a magnetic circuit Φ passing through the first and second magnetic responsive members 11 and 12, as indicated by a broken line in FIG. In the figure, the second magnetic response member 12
Due to the presence of the magnetic portion 12b, the magnetic circuit Φ is drawn so as not to reach the auxiliary magnetic response member M, but if this portion is an open portion due to the overlapping of the slits 11a and 12a, it is indicated by Φ ′. It goes without saying that the magnetic circuit reaches the auxiliary magnetic response member M as described above. The temperature compensation coil L2 is arranged close to the sensor coil L1, but is not affected by magnetic flux fluctuations according to the relative rotational position of the sensor coil L1 in the magnetic circuit Φ.

[0025] As shown in FIG.
In contrast, the temperature compensation coil L2 is connected in series to the sensor coil L1,
One output voltage Vx is extracted. The temperature compensation coil L2 does not respond to the relative positions of the first and second magnetic response members 11 and 12, and exhibits a constant impedance (inductance). It is preferable that the coil element has the same condition as the sensor coil L1 as much as possible, and that the coil element be disposed under the same environment as much as possible. Therefore, as described above, in the present embodiment, the same I-shaped (or H-shaped) cross section is used.
The sensor coil L1 and the temperature compensation coil L2 are housed in the ring-shaped magnetic bobbin (see FIG. 1A). The output voltage Vx of the sensor coil L1 is taken out based on the voltage division ratio between the sensor coil L1 and the temperature compensation coil L2, so that the temperature drift characteristics of both coils L1 and L2 are canceled out, and the output voltage Vx of the sensor coil L1 becomes The temperature is accurately compensated.

FIG. 3 shows slit holes 11a and 12a between the first and second magnetic response members 11 and 12 according to a change in the relative rotational position between the first and second shafts 2 and 3. It is a figure which shows the change of the degree of overlap (correspondence relationship) with magnetic body part 11b, 12b. FIG. 3C shows the slit hole 11 when the relative rotational position is 0 (that is, the amount of twist is 0).
The corresponding relationship between a and 12a and the magnetic portions 11b and 12b is shown. In this state, the slit hole 11a of the first magnetic response member 11 is
b and a half-overlap (ie, the first
Is shifted by 1/4 pitch between the slit 11a of the magnetic response member 11 and the slit 12a of the second magnetic response member 12), and the degree of magnetic coupling of the magnetic circuit Φ of the coil L1 passing through the magnetic response members 11 and 12 is as follows. Take an intermediate value.

FIG. 3B shows the first state from the intermediate state of FIG.
Shows a state in which the magnetic responsive member 11 has been rotated by a 1/4 pitch relative to the second magnetic responsive member 12 in the direction of the arrow CCW (that is, in the counterclockwise direction). In this state,
The slit hole 11a of the first magnetic response member 11 is completely closed by the magnetic portion 12b of the second magnetic response member 12, and the magnetic circuit Φ of the coil L1 passing through the magnetic response members 11 The coupling degree takes the maximum value.

FIG. 3A shows the first state from the intermediate state of FIG.
Of the magnetic response member 11 relative to the second magnetic response member 12 in the arrow CW direction (that is, clockwise direction).
This shows a state in which it is rotated by four pitches. In this state, the slit hole 11a of the magnetic response member 11 and the magnetic portion 12b of the second magnetic response member 12 do not overlap at all, and the slit holes 11a and 12a are completely overlapped and opened. The magnetic coupling degree of the magnetic circuit Φ of the coil L1 passing through the magnetic response members 11 and 12 takes the minimum value.

As described above, the first and second magnetic response members 11 and
As the degree of overlap between the twelve slit patterns 11a and 12a changes, the degree of magnetic coupling in the magnetic circuit Φ of the coil L1 changes, the self-inductance of the coil L1 changes, and its electrical impedance changes. Therefore, according to this impedance, the sensor coil L1
(Voltage between terminals) corresponds to the relative rotational position to be detected.

FIG. 4A is a graph illustrating the voltage (vertical axis) generated in the sensor coil L1 corresponding to the relative rotational position (horizontal axis x) to be detected. A, c, and b shown on the horizontal axis x correspond to the positions shown in FIGS. 3A, 3C, and 3B, and as described above, the positions corresponding to FIG. a, the coil L1
Is the minimum level (minimum amplitude coefficient). Further, at the position b corresponding to FIG. 3B, the voltage generated in the coil L1 is at the maximum level (maximum amplitude coefficient) because of the maximum impedance.

The voltage generated in the sensor coil L1 is the first
While the relative position of the second magnetic response members 11 and 12 moves from a to b, the relative position gradually increases from the minimum value to the maximum value. Assuming that the output voltage Vx of the coil L1 having the minimum value at the position a is Pa sinωt (Pa is the minimum impedance), this is set as the first reference voltage Va. That is, Va = Pa sin ωt. Further, the coil L1 having the maximum value at the position b
Is Pb sinωt (Pb sinωt)
Is the maximum impedance), which is set as the second reference voltage Vb. That is, Vb = Pb sin ωt.

As shown in FIG. 2B, each reference voltage V
a and Vb as a circuit for generating two coils L
a1, La2 in series and two coils Lb
1 and Lb2 are connected in series. These circuits are also driven by an AC signal from the AC generator 30. The reference voltage Va is extracted from a connection point between the coils La1 and La2, and the reference voltage Vb is extracted from a connection point between the coils Lb1 and Lb2. The impedance (inductance) of each pair of the coils La1, La2, L1 and L2 is appropriately adjusted so that desired reference voltages Va and Vb are obtained. Since the reference voltage Va is extracted based on the voltage division ratio of the coils La1 and La2, the coils La1 and L2
The temperature drift characteristic of a2 is canceled out, and the reference voltage Va is accurately temperature-compensated. Similarly, the coil Lb
Since the reference voltage Vb is extracted based on the voltage division ratio of Lb1 and Lb2, the temperature drift characteristics of the coils Lb1 and Lb2 are cancelled, and the reference voltage Vb is accurately temperature-compensated.

The arithmetic circuit 31A subtracts the first reference voltage Va from the output voltage Vx of the sensor coil L1, and calculates the amplitude coefficient of the coil output voltage Vx as a function A (x ), Is performed. At the start position a of the detection target section set by the first reference voltage Va, since A (x) = Pa, the amplitude coefficient “A (x) −Pa” of the calculation result is obtained.
Becomes "0". On the other hand, since A (x) = Pb at the end position b of the detection target section, the amplitude coefficient “A (x) −Pa” of this calculation result is “Pb−Pa”. Therefore, the amplitude coefficient “A (x) −Pa”
Indicates a function characteristic that gradually increases from “0” to “Pb−Pa” within the range of the detection target section. here,
Since “Pb−Pa” is the maximum value, if this is equivalently considered to be “1”, the amplitude coefficient “A (x) −Pa” of the AC signal according to the above equation is within the range of the detection target section. As shown in FIG. 4B, the amplitude characteristic changes from “0” to “1”.
The characteristics can be compared to the characteristics of the sine function sin θ in the first quadrant (that is, the range from 0 to 90 degrees) as shown in FIG. Therefore, the amplitude coefficient “A (x) −Pa” of the AC signal according to the above equation can be equivalently expressed using sin θ (however, approximately 0 ° ≦ θ ≦ 90 °). Note that FIG.
(B) and (C) show only the curve sinθ of the amplitude coefficient of the sine function characteristic with respect to the position x, but the actual output of the arithmetic circuit 31A is an AC signal sinθsinωt having an amplitude level corresponding to the amplitude coefficient sinθ. It is.

The arithmetic circuit 31B calculates the difference between the output voltage Vx of the detecting coil L1 and the second reference voltage Vb. Is performed. At the position a at the beginning of the detection target section,
Since A (x) = Pa, the amplitude coefficient “Pb−A (x)” of the calculation result is “Pb−Pa”. on the other hand,
At the position b at the end of the section set by the second reference voltage Vb, since A (x) = Pb, the amplitude coefficient “Pb−A (x)” of this calculation result is “0”. Therefore, the amplitude coefficient “Pb−A (x)” of the calculation result is
Within the range of the detection target section, a function characteristic that gradually decreases from “Pb−Pa” to “0” is shown. As before,
Assuming that “Pb−Pa” is equivalent to “1”, the amplitude coefficient “Pb−A (x)” of the AC signal according to the above equation becomes as shown in FIG. To
The amplitude coefficient changes from “1” to “0”, and the function characteristic of the amplitude coefficient is changed to the characteristic of the first quadrant (that is, the range of 0 to 90 degrees) of the cosine function as shown in FIG. Can be compared. Therefore, the amplitude coefficient “Pb−A (x)” of the AC signal according to the above equation is equivalent to cos θ
(However, approximately 0 ° ≦ θ ≦ 90 °). Also in this case, FIGS. 4B and 4C show only the curve cos θ of the amplitude coefficient of the cosine function characteristic with respect to the position x, but the actual output of the arithmetic circuit 31B is the amplitude corresponding to the amplitude coefficient cos θ. AC signal with level c
os θ sin ωt. Note that the subtraction in the arithmetic circuit 31B may be “Vx−Vb”.

Thus, two AC output signals sinθsinωt and cosθsinωt indicating the amplitudes according to the sine and cosine function characteristics according to the position x to be detected, respectively.
Can be generated. This is similar to the form of the output signal of a position detector generally called a resolver,
It can be used effectively. For example, the arithmetic circuit 31
A, 31B, and outputs the two resolver type AC output signals to a phase detection circuit (or an amplitude phase conversion unit) 3
2 to measure the phase value θ of the sine and cosine functions sin θ and cos θ that define the amplitude value from the correlation between the amplitude values of the two AC output signals, thereby detecting the position to be detected absolutely. be able to. The phase detection circuit 32 may be configured using, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 9-126809 filed by the present applicant. For example, by electrically shifting the first AC output signal sinθsinωt by 90 degrees, an AC signal sinθcosωt is generated, and by adding and subtracting this and the second AC output signal cosθsinωt, sin (ωt + θ) and sin (ωt + θ) ωt-θ)
The position detection data is generated by generating two AC signals (signals obtained by converting the phase component θ into an AC phase shift) that are phase-shifted in the leading and lagging directions according to θ, and measuring the phase θ. Can be obtained. The phase detection circuit 32
It may be composed of a dedicated circuit (for example, an integrated circuit device)
The phase detection processing may be performed by executing predetermined software using a programmable processor or a computer. Alternatively, an R-D converter used for processing a known resolver output may be used as the phase detection circuit 32. Further, the detection processing of the phase component θ in the phase detection circuit 32 is not limited to digital processing, but may be performed by analog processing using an integration circuit or the like. In addition, after digital detection data indicating the rotational position θ is generated by digital phase detection processing, the digital
May be obtained. Of course, without providing the phase detection circuit 32, the arithmetic circuits 31A, 3A
1B output signals sin θ sin ωt and cos θ sin
ωt may be output as it is.

As shown in FIG. 4B, an AC output signal sinθsinωt having sine and cosine function characteristics
And cos θ sin ωt have a phase angle θ
Assuming that the correspondence between the detection target position x and the detection target position x has linearity, it does not show true sine and cosine function characteristics as shown in FIG. However, the phase detection circuit 32 apparently performs the phase detection processing assuming that the AC output signals sin θ sinωt and cos θ sinωt have amplitude characteristics of sine and cosine functions, respectively. As a result, the detected phase angle θ is
It will not show linearity. However, in position detection, the non-linearity between the detection output data (the detected phase angle θ) and the actual detection target position is not a very important problem. In other words, it suffices if position detection can be performed with a predetermined reproducibility. Also,
If necessary, the output data of the phase detection circuit 32 is subjected to data conversion using an appropriate data conversion table, so that accurate linearity can be easily provided between the detected output data and the actual detection target position. Can be done. Therefore, the amplitude characteristics of the sine and cosine functions referred to in the present invention do not have to indicate the true sine and cosine function characteristics, and as shown in FIG. What is necessary is just to show such a tendency. That is,
Any function similar to a trigonometric function such as sine may be used. In the example of FIG. 4B, the scale of the horizontal axis is assumed to be θ, and the scale of the horizontal axis is assumed to be x if the scale is formed of a required non-linear scale. In this case, even if it looks like a triangular wave, it can be said that θ is a sine function or a cosine function.

Here, further compensation of the temperature drift characteristic will be described. As described above, the output voltage Vx of the sensor coil L1 and the reference voltages Va and Vb are temperature drift compensated, respectively.
By the difference calculation in B, even if there is a level fluctuation error in the same direction, this is also canceled, and the temperature drift characteristic is more reliably compensated.

Each coil La1, La for generating a reference voltage
2, Lb1 and Lb2 use coils having the same characteristics as the sensor coil L1, and these coils La1 and Lb2 are used.
It is preferable to place them in the same temperature environment as that of the sensors a2, Lb1, Lb2 and the sensor coil L1 (that is, to place them relatively close to the sensor coil L1). This is because temperature drift compensation is achieved by series connection of each pair of coils and voltage extraction from the connection point as shown in FIG. Therefore,
Each coil La1, La2, Lb1, L for generating a reference voltage
b2 may be provided on the circuit board side of the arithmetic circuits 31A and 31B.

As described above, the temperature compensation coil L2 connected in series to the sensor coil L1 is disposed near the sensor coil L1 and is preferably placed in the same environment as much as possible. Calculation circuit 31
A and 31B may be provided on the circuit board side. Of course, the temperature compensation coil L2 and the reference voltage generating coils La1,
La2, Lb1 and Lb2 are arranged so as not to be affected by the impedance change due to the change of the slit pattern of the first and second magnetic response members 11 and 12. In order to generate the predetermined reference voltages Va and Vb at a constant voltage, an appropriate masking member made of a magnetic material such as iron, a conductor such as copper, or a hybrid structure thereof is used for generating these reference voltages. Coils La1, La2, L
It is preferable to set the inductance, that is, the impedance, on b1 and Lb2. In a similar manner, the inductance, that is, the impedance of the temperature compensation coil L2 can be set and adjusted.

FIG. 5 shows the reference voltage generating coils La1, L
An example of a method of setting the inductance of a2, Lb1, and Lb2, that is, the impedance will be described. A pair of coils La1,
The magnetic core Ma is variably inserted into La2, and by adjusting the arrangement thereof, the two coils La1, La2
, The amount of penetration of the magnetic core Ma into each of them is adjusted differentially, and the level of the reference voltage Va can be variably adjusted. Similarly, the magnetic core Mb is variably inserted into the pair of coils Lb1 and Lb2, and by adjusting the arrangement thereof, the penetration amount of the magnetic core Mb into each of the two coils Lb1 and Lb2 is different. It is dynamically adjusted, and the level of the reference voltage Vb can be variably adjusted.

The circuit for generating a reference voltage is not limited to a coil.
A resistor or other suitable constant voltage generating circuit may be used.
In the example of FIG. 1, the axis of the sensor coil L1 is in the same direction (thrust direction) as the axis of the rotating shafts 2 and 3.
The arrangement is not limited to this, and the arrangement may be such that the direction of the axis of the sensor coil L1 is the radial direction of the rotating shafts 2 and 3.

The magnetic responsive members 11 and 12 may be made of a nonmagnetic good conductor such as copper instead of a magnetic material. In this case, the inductance of the coil is reduced due to eddy current loss due to the presence of the conductor portions 11b and 12b of the magnetic response members 11 and 12, and the conductor portions 11b and 12b of the first and second magnetic response members 11 and 12 are reduced. As the area for closing the other slit holes 11a and 12a increases, the level of the voltage induced in the coil decreases. Also in this case, the position detection operation can be performed in the same manner as described above.
Further, the pitch P (the number of slit holes per circumference) of the slit portions 11a and 12a in the first and second magnetic response members 11 and 12 is not limited to the illustrated one, but may be appropriately set as a design item. Good. In addition, the shape of the slit pattern in the first and second magnetic response members 11 and 12 is not limited to the above-described substantially rectangular repeating pattern. For example, it may have a slit shape with a gradually decreasing or increasing triangular shape, or may have any other appropriate shape.

As another modification, the magnetic responsive members 11, 1
2 may include a permanent magnet, and the coil of the coil unit 10 may include an iron core. When the permanent magnet approaches the coil, the iron core corresponding to the location near the coil is partially in a magnetically saturated or supersaturated state, and the voltage between terminals of the coil is reduced. Thereby, it is possible to cause a gradual decrease (or a gradual increase) change in the voltage between the terminals of the coil according to the relative displacement of the magnetic response members 11 and 12.

Next, an embodiment of a relative rotational position detecting device according to the present invention using an Oldham mechanism will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 6 is an exploded perspective view showing the structure of the detection device, and FIG. 7 is a schematic sectional view of the detection device in the axial direction. FIG. 7 shows a half section, but the other half appears symmetrically. As shown in the example of FIG.
In a structure in which the eccentricity, eccentricity, and axial movement occur between the input shaft 2 and the output shaft 3 in the structure in which the eccentricity, eccentricity, and axial movement occur between the input shaft 2 and the output shaft 3 With the movement, the positional relationship between the magnetic responsive members 11 and 12 is distorted, and the area or distance of the air gap in the magnetic circuit is fluctuated, which may cause a detection error. Of course, if the present invention is applied to a mechanism in which eccentricity, declination, and axial movement do not occur between the input shaft 2 and the output shaft 3, no problem occurs in the embodiment of FIG. However, for example, in an application in which the present invention is applied for detecting the torque of the steering shaft of an automobile, the bending force is applied to the steering wheel shaft (input shaft 2) depending on how to add the value from the value at the time of steering operation. Appropriate measures need to be taken because forces other than in the equal rotation direction are often applied. In view of this point, in the present invention, each magnetic response member 11,
When the 12 is arranged, it is characterized in that an unwanted movement other than the rotation direction is prevented from being transmitted from the shafts 2 and 3 to the magnetic responsive members 11 and 12 by interposing an Oldham mechanism. In the embodiment shown in FIGS. 6 and 7, when the first magnetic response member 11 is arranged on the input shaft 2, an Oldham mechanism is interposed.

6 and 7, the Oldham mechanism is constituted by flanges F1 and F2 and rings S1 and S2, and is interposed between the input shaft 2 and the first magnetic response member 11. The components other than the Oldham mechanism and the principle of position detection in this detection device may be the same as those in the embodiment of FIGS. 1 to 5. A configuration example of the Oldham mechanism in the detection device will be described in detail. 6 and 7, the input shaft 2 and the output shaft 3
Are connected by a torsion bar 1. A flange F1 is attached to the input shaft 2 and a flange F is attached to the output shaft 3.
2 is attached. A key groove Fb extending in the axial direction is provided at a predetermined location inside the flange F1, and a key projection Fc is provided at a predetermined location outside the input shaft 2. When attaching the flange F1 to the input shaft 2, the flange F1
The key projection Fc of the input shaft 2 is fitted into the key groove Fb. Thereby, the flange F1 is connected to the input shaft 2
, But does not follow the backlash of the input shaft 2 in the axial direction, so that unwanted movement in the axial direction can be canceled.

The rings S1 and S2 are engaged with the flange F1, and these rings S1 and S2 rotate integrally with the flange F1 in the rotation direction, but in the axial cross section, that is, in the radial plane. It can move freely within a certain range with respect to the directions of orthogonal coordinate axes (referred to as x-axis and y-axis) on a plane. That is, in the flange F1, one coordinate axis (for example, y
(In the form of an axis), two elongated through holes Fa are formed at predetermined positions at intervals of 180 degrees.
The ring S1 is attached to the flange F1 such that the protrusion Sb formed on the ring S1 is fitted to the flange F1. Therefore, the ring S1 rotates integrally with the flange F1, but the movement in the y-axis direction of the flange F1, that is, the axial cross section of the input shaft 2 is canceled by the play of the elongated hole Fa and is not transmitted to the ring S1. The ring S1 has two elongated holes Sa at positions shifted by 90 degrees from the protrusions Sb (that is, in the x-axis direction of the axial cross section).
The ring S2 is attached to the ring S1 so that the projection Sc formed on the ring S2 fits into the elongated hole Sa at an interval of 0 degrees. Therefore, the ring S2 rotates integrally with the ring S1 and the flange F1, but the movement of the ring S1, that is, the flange F1, that is, the axial cross section of the input shaft 2 in the x-axis direction is canceled by the play of the long hole Sa, and the ring S2 is rotated. Is not transmitted to The first magnetic response member 11 is fixed to the ring S2. By canceling the movement of the axis cross section in the x-axis and y-axis directions, the movement of the axis cross section on the plane is canceled. Thus, a total of 3 in the axial direction and the planar direction of the axial cross section is obtained.
The axial movement is canceled, and only the rotational movement of the input shaft 2 is transmitted to the ring S2, that is, the first magnetic responsive member 11.

On the other hand, the second magnetic responsive member 12 and the auxiliary magnetic responsive member M are mounted on the flange F2 mounted on the output shaft 3, and these rotate integrally with the output shaft 3. The first magnetic response member 11 is provided between the flange F2 on the output shaft 3 side and the auxiliary magnetic response member M between the first magnetic response member 11 and the ring S2.
And a second magnetic response member 12, which jumps over them and is bridged to and connected to the ring S2. Such a bridged coupling arrangement is only a design convenience. In short, the first magnetic response member 11
Is mechanically coupled only to the ring S2 on the input shaft 2 side, but is not coupled to the flange F2, the auxiliary magnetic responsive member M, and the second magnetic responsive member 12 on the output shaft 3 side. Just fine. The housing K is fixed to a frame (not shown) and is free from the input shaft 2 and the output shaft 3. The coil unit 1 is located at a predetermined position in the housing K.
0 is placed. Therefore, the coil unit 10 is also free from the input shaft 2 and the output shaft 3.

The inner periphery of the flange F2 is a circular projection Fc which fits in the circular hole Se on the inner periphery of the ring S2 so that the center of the flange F2 and the ring S2 are aligned. Further, a convex portion Fb is formed at a predetermined position of the circular projection Fc of the flange F2, and a concave portion Sd is formed at a predetermined position of the circular hole Se of the ring S2 correspondingly. The circumferential size of the concave portion Sd formed in the ring S2 is larger than the circumferential size of the convex portion Fb formed in the flange F2.
b is fitted so that it fits loosely into the concave portion Sd of the ring S2. That is, the convex portion Fb can move within the concave portion Sd within a predetermined angle range, and this angle range is larger than the maximum twist angle of the torsion bar 1. That is, since the maximum torsion angle of the torsion bar 1 is naturally limited, the loose fitting between the convex portion Fb of the flange F2 and the concave portion Sd of the ring S2 causes the input shaft 2 and the torsion bar 1 within the maximum torsion angle. The relative rotational displacement of the output shaft 3 is not hindered at all. The convex portion Fb and the concave portion Sd are convenient because the first magnetic responsive member 11 and the second magnetic responsive member 12 can be easily arranged with their origins aligned during assembly. However, these convex portions Fb and concave portions Sd
Is for convenience in assembling and is not related to the essence of the invention, so that it can be omitted. Also,
The centering structure of the flange F2 and the ring S2 allows the first magnetic responsive member 11 and the second magnetic responsive member 1
It is easy to arrange the two in a state of being accurately centered, and the relationship between the two except for the rotation direction is maintained in a predetermined relationship. That is, the flange F2 and the ring S2 are rotatable relative to each other (within a range in which the convex portion Fb can move within the concave portion Sd), and other positional relationships can maintain a constant relationship without rattling. As a result, error-free detection is possible.

With the above arrangement, when eccentricity, declination, and axial movement occur between the input shaft 2 and the output shaft 3, such eccentricity, declination, and axial movement are canceled by the Oldham mechanism. Only the relative rotational movement between them is transmitted to the first and second magnetic responsive members 11 and 12. Therefore, no distortion occurs in the mutual positional relationship between the first and second magnetic response members 11 and 12, and an undesired change does not occur in the area or distance of the air gap in the magnetic circuit.
There is no detection error. The detection according to the relative rotational position of the first and second magnetic response members 11 and 12 is the same as in the embodiment of FIGS. The constituent elements F1, F2, S1, and S2 of the Oldham mechanism use a non-magnetic and non-conductive material such as plastic.

Next, another embodiment of the relative rotational position detecting device according to the present invention using the Oldham mechanism will be described with reference to FIGS. FIG. 8 is an exploded perspective view showing the structure of the detection device, and FIG. 9 is a schematic sectional view of the detection device in the axial direction. FIG. 9 shows a half section, but the other half appears symmetrically. The embodiment of FIGS. 8 and 9 differs from the embodiment of FIGS. 6 and 7 in that the shapes of the magnetic responsive members 13 and 14 are different and the configuration of the mechanism related thereto is different in design. The only difference is that they are substantially the same. In the embodiment of FIGS. 8 and 9, the first and second magnetic responsive members 13 and 14 provided on the input shaft 2 and the output shaft 3 are made of, for example, a cylindrical magnetic body and are provided repeatedly at a predetermined pitch P. The tooth-shaped protrusions 13a and 14a face each other in a non-contact manner. As shown in FIG. 9, in the coil unit 10, the sensor coil L <b> 1 includes tooth-shaped protrusions 13 a, 14
It is arranged on the outer periphery so as to cover the portion a. As described above, the tooth-shaped convex portions 13a, 14 of the magnetic response members 13, 14 are provided.
The coil L2 for temperature compensation is provided in the coil unit 10 so as not to be affected by the magnetic change due to the a.

The Oldham mechanism includes a flange F1 and a ring S
1, S2. As described above, the keyway F extending in the axial direction is provided at a predetermined position inside the flange F1.
The key projection Fc is provided at a predetermined position outside the input shaft 2, and the key projection Fc of the input shaft 2 is attached so as to fit into the key groove Fb of the flange F 1.
Also, the engagement structure between the flange F1 and the ring S1 and the engagement structure between the rings S1 and S2 are similar to those described above.
This is via the Sa and the protrusions Sb and Sc. Ring S2
, A first magnetic response member 13 having a plurality of tooth-shaped convex portions 13a is attached thereto, and integrally rotates. The ring S2 for mounting the first magnetic response member 13 is, for example, a non-magnetic ring.
A material that exhibits diamagnetic properties due to eddy current loss with respect to magnetism, such as a good conductor, may be used.

The end projection 2 a of the input shaft 2 is loosely fitted into the end recess 3 a of the output shaft 3, and the input shaft 2 and the output shaft 3
Are connected via the torsion bar 1. Input shaft 2
6 is loosely fitted to the end concave portion 3a of the output shaft 3 in the same manner as the engagement structure of the convex portion Fb and the concave portion Sd in FIG. Within a predetermined angular range, which is greater than the maximum torsion angle of the torsion bar 1. That is, since the maximum torsion angle of the torsion bar 1 is naturally limited,
The loose fit between the convex portion 2a of the input shaft 2 and the concave portion 3a of the output shaft 3 causes the input shaft 2 within the maximum torsion angle of the torsion bar 1.
And the relative rotational displacement of the output shaft 3 is not hindered at all. The ring S2 on the input shaft 2 side is rotatably supported on the output shaft 3 via a bearing B. Output shaft 3
, A mounting ring SR is attached so as to rotate integrally, and the second magnetic responsive member 14 is attached to the attachment ring SR so as to rotate integrally. The attachment ring SR may also be made of a material exhibiting diamagnetic characteristics due to eddy current loss with respect to magnetism, such as a non-magnetic and good conductor. The first magnetic responsive member 13 and the second magnetic responsive member 14 face each other through a slight gap in a non-contact manner, and the first magnetic responsive member 13 rotates integrally with the input shaft 2, and The magnetic response member 14 rotates integrally with the output shaft 3. And with the intervention of the Oldham mechanism,
Mechanical rattling (axial movement, shaft bending or axial misalignment, etc.) other than the rotation direction between the input shaft 2 and the output shaft 3 is absorbed by the Oldham mechanism, and the first magnetic response member 13 The arrangement of the second magnetic response member 14 remains constant with respect to movement other than relative rotational movement. Since the ring S2 on the input shaft 2 side is rotatably supported on the output shaft 3 via the bearing B, the center of the first magnetic responsive member 13 and the second magnetic responsive member 14 A match is made.

FIG. 10 is a diagram showing the correspondence between the uneven teeth on the first and second magnetic response members 13 and 14 according to the change in the relative rotational position between the first shaft 2 and the second shaft 3. FIG. 7 is a development view showing a change in the state. FIG. 10C shows the correspondence between the uneven teeth when the relative rotational position is 0 (that is, the amount of twist is 0). In this state, the respective magnetic response members 13 and 1
No. 4 of the protrusions 13a, 14a correspond to the recesses 13b, 14b in half.
4), the magnetic coupling degree of the magnetic circuit Φ of the sensor coil L1 passing through the magnetic response members 13 and 14 has an intermediate value.

FIG. 10B shows that the first magnetic responsive member 13 is moved from the intermediate state of FIG. 10C by 1/4 in the direction of the arrow CW (clockwise) relative to the second magnetic responsive member 14. This shows a state rotated by the pitch. In this state, the convex portions 13a and 14a of the magnetic response members 13 and 14 and the concave portions 13b and 14b just coincide with each other (there is no displacement of the concave and convex teeth of the magnetic response members 13 and 14). The degree of magnetic coupling of the magnetic circuit Φ of the coil L1 passing through the members 13 and 14 has a maximum value.

FIG. 10 (a) shows that the first magnetic response member 13 is moved relative to the second magnetic response member 14 in the direction of arrow CCW (counterclockwise) from the intermediate state of FIG. 4
This shows a state rotated by the pitch. In this state, the convex portions 13a, 14a and the concave portions 13b, 14b of the magnetic response members 13, 14 correspond to each other in reverse (the magnetic response member 1).
3 and 14), the degree of magnetic coupling of the magnetic circuit Φ of the coil L1 passing through the magnetic response members 13 and 14 takes a minimum value.

As described above, the first and second magnetic responsive members 13,
By changing the relative positions of the fourteen uneven teeth 13a, 14b, 14a, 14b, the degree of magnetic coupling in the magnetic circuit Φ of the coil L1 changes, the self-inductance of the coil L1 changes, and the electrical impedance changes. I do.
I do. Therefore, the voltage (inter-terminal voltage) generated in the sensor coil L1 according to the impedance corresponds to the relative rotational position to be detected. Therefore, position detection can be performed according to the same principle as described above with reference to FIG. That is, a predetermined operation is performed on each of the obtained voltages to generate two AC output signals sinθsinωt and cosθsinωt that respectively indicate amplitudes that follow the sine and cosine function characteristics equivalently according to the detection target position x. Can be. And
By measuring the phase value θ of the sine and cosine functions sin θ and cos θ, the detection target position can be absolutely detected.

In each of the above embodiments, the configuration for obtaining the position detection data is not limited to the configuration using the phase detection circuit 32 as shown in FIG. 2B, but as shown in FIG. The voltage detection circuit 40 may be used. 11A, the configuration other than the voltage detection circuit 40 is the same as that shown in FIG. 2B. In short, in the voltage detection circuit 40, an AC signal sin θ sin having an equivalently sine function amplitude characteristic output from the arithmetic circuit 31A
ωt is input to the rectifier circuit 41 to remove an AC signal component,
DC detection voltage V responding only to amplitude voltage component sin θ
Generates 1. Further, an AC signal cos θ having an amplitude characteristic of a cosine function equivalently output from the arithmetic circuit 31B.
The sin ωt is input to the rectifier circuit 42 to remove an AC signal component and generate a DC detection voltage V2 that responds only to the amplitude voltage component cos θ. FIG. 11B shows the detection target position x.
That is, the detection voltages V1 and V shown with respect to the relative rotation angle
2 shows a characteristic example. The reason why such characteristics are obtained is as described above with reference to FIG. In this manner, two types of detection voltages V1 and V2 having exactly opposite characteristics can be obtained in analog form. To detect the detection target position x, that is, the relative rotation angle, one of the detection voltages V
It is sufficient to configure only one series of rectifier circuits so as to obtain only V1 and V2, but two types of detection voltages V1 and V2 having opposite characteristics are sufficient.
Are generated in parallel, redundancy can be provided. That is, when any failure occurs in either one of the detection sequences, it is possible to appropriately cope with the failure.

FIG. 12 shows an analog circuit 32A for phase detection.
A configuration example in which a voltage detection circuit 40 and a voltage detection circuit 40 are provided together so that both phase detection and voltage detection can be adopted. FIG.
Is the phase detection analog circuit 32 in FIG.
It is the same as the one with A added. Therefore, the description of the configuration other than the phase detection analog circuit 32A will be described with reference to FIG.
The description of FIG. 11B and FIG. In an analog circuit for phase detection 32A, an AC signal A having an amplitude characteristic of a sine function equivalently output from the arithmetic circuit 31A
= Sinθsinωt is input to the phase shift circuit 19, and its electric phase is phase-shifted by a predetermined amount.
AC signal A '= sin advanced by 0 degree and phase shifted
θ · cosωt is obtained. The phase detection analog circuit 32A includes an addition circuit 15 and a subtraction circuit 16, and the addition circuit 15 includes a phase shift circuit 19
The phase-shifted AC signal A ′ = si output from
nθ · cosωt and an AC signal B = cosθ equivalently having an amplitude characteristic of a cosine function output from the arithmetic circuit 31B
sinωt and B +
A ′ = cosθ · sinωt + sinθ · cosωt = sin (ωt +
The first electrical AC signal Y1 can be obtained, which can be represented by the simplified expression θ). The subtraction circuit 16 subtracts the phase-shifted AC signal A ′ = sinθ · cosωt from the arithmetic circuit 31B and the output AC signal B = cosθ · sinωt, and obtains B−A ′ = cosθ · sinωt as a subtraction output. −sinθ ・ cosω
As a result, a second electrical AC signal Y2 can be obtained, which can be represented by a simplified expression of t = sin (ωt−θ). Thus, the first electrical AC output signal Y1 = sin having the electrical phase angle (+ θ) shifted in the positive direction corresponding to the detection target position (x)
(Ωt + θ), a second electrical AC output signal Y2 = sin (ωt−θ) having an electrical phase angle (−θ) shifted in the negative direction corresponding to the same detection target position (x). But,
Each is obtained by electrical processing.

The output signals Y1 and Y2 of the adder circuit 15 and the subtractor circuit 16 are input to zero-cross detection circuits 17 and 18, respectively, where the respective zero-crosses are detected. As a method of detecting the zero cross, for example, a zero cross in which the amplitude values of the signals Y1 and Y2 change from negative polarity to positive polarity, that is, zero phase is detected. The zero-cross detection pulse, that is, the zero-phase detection pulse detected by each of the circuits 17 and 18 is output as latch pulses LP1 and LP2. Latch pulse LP
1 and LP2 are input to a phase shift measuring device (not shown). In this phase shift measuring device, the time difference from the zero-phase time point of the reference AC signal sinωt generated from the reference AC signal source 30 to the generation time point (rising trigger time point) of each of the latch pulses LP1 and LP2 is counted, and the latch pulse LP1 is counted. The corresponding count value is detected as phase data of the phase angle (+ θ) shifted in the positive direction, and the count value corresponding to the latch pulse LP2 is detected as phase data of the phase angle (−θ) shifted in the negative direction. . The method of using the phase detection data of the phase angles + θ and −θ shifted in the positive direction and the negative direction is described in the above-mentioned prior application of the present applicant. You just have to use it in the method.

When the oscillation circuit itself of the reference AC source 30 is provided on the side of the coil section 10, the reference AC signal generated from the reference AC source 30 is converted into a square wave conversion circuit as shown in FIG. 20 and the reference AC signal sin
A square wave signal (pulse signal) synchronized with ωt is formed, and this is input to the phase shift measuring device. In that case,
In the phase shift measuring device, the input reference AC signal sin
The clock pulse count is performed in synchronization with the rise of the square wave signal (pulse signal) synchronized with ωt, and the count value is latched at the time when each of the latch pulses LP1 and LP2 occurs (at the time of the rising trigger). As described above, the phase detection data of the phase angles + θ and −θ shifted in the positive direction and the negative direction can be obtained, respectively. Of course, the present invention is not limited to this. On the side of the phase shift measuring device, a square wave signal (pulse signal) synchronized with the reference AC signal sinωt is generated, and based on the square wave signal (pulse signal), The analog reference AC signal sin
ωt may be generated. In that case, on the side of the phase shift measuring device, the output reference AC signal sinωt
The clock pulse count is performed in synchronization with the rise of the square wave signal (pulse signal) synchronized with the clock pulse, and the generation time of each latch pulse LP1, LP2 (the rise trigger time)
And a configuration for latching the count value may be adopted.
As the phase shift measuring device, a processor such as a CPU capable of processing a software program may be used. In the circuit of FIG. 12, as the signal input to the rectifier circuit 41 of the voltage detection circuit 40, instead of the output signal A of the arithmetic circuit 31A = sin θ sinωt, the output signal A ′ = sin θ cosωt from the phase shift circuit 19 is input. You may do so.

The configuration of the coil in the coil section 10 is not limited to the type in which only one sensor coil L1 is provided as in the above embodiment. For example, a one-phase AC signal (s
(inωt), by disposing a plurality of sensor coils at different positions, extracting output voltages of the respective sensor coils, and calculating the extracted voltages in an appropriate combination to obtain an equivalent sine phase. Output signal (sin
θ sinωt) and the cosine phase output signal (cos θ sin
ωt) may be obtained. Alternatively, at least one primary coil excited by a one-phase AC signal (sinωt) and a sine-phase output signal (sinθsinω), as is known in a normal resolver device or the like.
t) and a cosine phase output signal (c
osθ sinωt), and a sine phase output signal (sin θs) is output from each secondary coil.
inωt) and the cosine phase output signal (cos θ sinω
t) may be obtained directly. In that case, Figure 2
(B) It goes without saying that the arithmetic circuits 31A and 31B described above can be omitted. If necessary, at least two primary coils excited by a two-phase AC signal (for example, sinωt and cosωt) and an AC output signal (sin (ωt + θ)) phase-shifted according to the position to be detected are output. A secondary coil may be provided.

The relative rotational position detecting device according to the present invention comprises:
The present invention can be applied not only to the torsion amount detecting device or the torque sensor but also to, for example, an engine injection timing control sensor for detecting a relative rotation angle of an engine overhead cam. In other words, the sensor is suitable as a sensor for detecting a relative rotational position such as a twist amount or a rotational deviation over a predetermined angular range of two rotatable axes.

[0063]

As described above, according to the first aspect of the present invention, a magnetic responsive member is disposed on each of the first and second shafts that are relatively rotated and displaced, and the relative magnetic responsive members are positioned relative to each other. In a detection device of the type that detects the relative rotational positional relationship in a non-contact manner using a coil, unnecessary movements other than the rotation directions of the first and second shafts are canceled by interposing an Oldham mechanism, and both Since these unnecessary movements do not affect the relative rotational positional relationship of the magnetic response member, even if there is undesired play other than the rotational direction in the relative relationship between the first and second axes. This makes it possible to perform highly accurate detection.

Further, according to the second aspect of the present invention, 1
An analog DC voltage indicating the relative rotational position of the first and second shafts can be obtained using one sensor coil, and in that case, a temperature compensation coil connected in series to the sensor coil is provided. Since the output voltage of the sensor coil that changes based on the impedance change of the sensor coil is taken out from the connection point between the sensor coil and the temperature compensation coil, the temperature drift of the coil is appropriately canceled. In addition, the output voltage whose temperature drift has been compensated can be extracted, and the detection accuracy is improved. Also, by generating a predetermined reference voltage composed of an AC signal, calculating the output signal of the sensor coil and the reference voltage, and generating an AC output signal having an amplitude coefficient corresponding to the relative rotational position. In addition, the amplitude characteristic of the output signal of the sensor coil can be set to a desired characteristic, and control can be easily performed so that an analog DC voltage having the desired characteristic is obtained.

According to a third aspect of the present invention, the first and second magnetic response members disposed on the first and second shafts respectively include a plurality of slits at predetermined intervals in the rotational direction. The magnetic coupling to the coil portion is changed by the degree of overlap of the slit portions of the respective magnetic response members according to the relative rotation position. The structure of the first and second magnetic response members becomes a flat and compact structure as a whole, and can be much simpler, smaller, and more compact than a structure in which large uneven teeth are provided. it can.

Further, by using only one coil (ie, a sensor coil) excited by one-phase alternating current and calculating the output voltage and the reference voltage, an output showing the amplitude function characteristics of a plurality of phases is obtained. Since the AC signal can be configured to be generated in accordance with the relative position to be detected, in such a configuration, a secondary coil is not required, so that a small and simple structure is used. A rotational position detection device can be provided. Moreover, by adopting the phase detection method as required, it is possible to detect the relative rotational position with higher accuracy.

[Brief description of the drawings]

FIG. 1 shows an example of the structure of a relative rotational position detecting device according to an embodiment of the present invention, where (A) is an exploded perspective view,
(B) is a front view showing an example of the whole shape of the first magnetic response member, and (C) is a front view showing an example of the whole shape of the second magnetic response member.

2A is a schematic cross-sectional view in the axial direction of the detection device shown in FIG. 1, and FIG. 2B is an electric circuit diagram relating to a coil portion of the detection device.

FIG. 3 is a view showing some typical examples of a relative rotational positional relationship between first and second magnetic response members in the embodiment.

FIG. 4 is an explanatory diagram of a detection operation of the detection device shown in FIG.

FIG. 5 is a schematic view showing an example of a method of adjusting the impedance of a reference voltage generating coil in the detection device shown in FIG. 1;

FIG. 6 is a schematic exploded perspective view showing an embodiment of a relative rotational position detecting device according to the present invention including an Oldham mechanism.

7 is a schematic cross-sectional view in the axial direction of the detection device shown in FIG.

FIG. 8 is a schematic exploded perspective view showing another embodiment of the relative rotational position detecting device according to the present invention including the Oldham mechanism.

9 is a schematic cross-sectional view in the axial direction of the detection device shown in FIG.

FIG. 10 is a diagram illustrating a detection operation of the detection device illustrated in FIG. 8;

FIG. 11 is a circuit diagram showing an embodiment of a relative rotation position detection device according to the present invention configured to generate an analog DC voltage according to a relative rotation position.

FIG. 12 is a circuit diagram showing an embodiment of a relative rotational position detecting device according to the present invention having both functions of voltage detection and phase detection.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Torsion bar 2 Input shaft (1st axis) 3 Output shaft (2nd axis) 10 Coil part L1 Sensor coil L2 Temperature compensation coil 11, 12, 13, 14 Magnetic response member 11a, 12a Slit part 13a, 14a Convex part 13b, 14b Concave part 30 AC source 31A, 31B Analog operation circuit 32 Phase detection circuit La1, La2, Lb1, Lb2 Reference voltage generating coil S1, S2 Ring F1, F2 Flange SR Shield ring M Auxiliary magnetic response Member 40 Voltage detection circuit 41, 42 Rectifier circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA34 AA36 BA08 CA40 CB01 CC04 DA05 EA03 GA07 GA08 KA01 2F077 AA13 AA49 CC02 FF02 FF13 FF31 UU07 VV02

Claims (17)

[Claims] 1. A relative rotation position detection device for detecting a relative rotation position of a first and a second shaft which are relatively rotatable, wherein at least one coil excited by an AC signal is arranged. And a first and a second magnetic responsive member disposed on the first and second shafts, which are magnetically coupled to the coil portion, and correspond to the relative rotational position. The relative position of the first and second magnetic response members changes, and an output corresponding thereto is generated from the coil unit; and at least one of the first and second axes, and A relative rotation position detection device provided between at least one of the first and second magnetic response members to be disposed and an Oldham mechanism for absorbing unnecessary movement of a shaft other than the rotation direction. 2. The relative rotational position detecting device according to claim 1, wherein the first and second shafts are connected by a torsion bar. A circuit for generating a predetermined reference voltage composed of an AC signal; an output signal of the coil unit and the reference voltage being calculated; and an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient. The relative rotational position according to claim 1 or 2, further comprising two arithmetic circuits, wherein the periodic amplitude function of each of the AC output signals is different in a periodic characteristic by a predetermined phase. Detection device. 4. The sensor according to claim 1, wherein the coil unit includes one sensor coil that is excited by an AC signal, and a relative position of the first and second magnetic response members is changed according to the relative rotation position. And the impedance of the sensor coil changes in response to the change. The temperature compensation coil connected in series to the sensor coil, and a connection point between the sensor coil and the temperature compensation coil, 4. The relative rotational position detecting device according to claim 1, further comprising a circuit for extracting an output signal of the sensor coil that changes based on a change in impedance of the sensor coil. 5. The relative rotational position detecting device according to claim 4, further comprising a circuit for rectifying an output signal to generate a DC voltage having a level corresponding to the relative position. 6. The coil unit includes a primary coil and at least two secondary coils, and at least two AC output signals having a predetermined periodic amplitude function as an amplitude coefficient are generated from the secondary coil; 3. The relative rotational position detecting device according to claim 1, wherein the periodic amplitude functions of the respective AC output signals are different from each other by a predetermined phase in their periodic characteristics. 7. A relative rotation position detection device for detecting a relative rotation position of a first and a second shaft which are relatively rotatable, wherein one sensor coil excited by an AC signal is arranged. And a first and a second magnetic response member disposed on the first and second shafts, which are magnetically coupled to the coil portion and correspond to the relative rotational position. The relative position of the first and second magnetic response members is changed, and an output corresponding to the change is generated from the sensor coil; a temperature compensation coil connected in series to the sensor coil; A circuit for extracting an output signal of the sensor coil that changes based on a change in impedance of the sensor coil from a connection point between the sensor coil and the temperature compensation coil; and rectifying the output signal to obtain the relative rotational position. Corresponding to The relative rotational position detection device comprising a rectifier circuit for obtaining a DC voltage of the bell. 8. A circuit for generating a predetermined reference voltage consisting of an AC signal, an AC output signal having an amplitude coefficient corresponding to the relative rotational position, calculating an output signal of the sensor coil and the reference voltage. The circuit according to claim 7, further comprising: an arithmetic circuit that generates a DC voltage of a level corresponding to the relative rotational position by inputting an AC output signal of the arithmetic circuit to the rectifier circuit. Relative rotational position detection device. 9. The arithmetic circuit includes: a first AC output signal having a predetermined first function related to the relative rotational position as an amplitude coefficient; and a second function having a characteristic inverse to the first function. A second AC output signal having an amplitude coefficient, wherein the rectifier circuit rectifies the first and second AC output signals, respectively, and a DC voltage having a level corresponding to the relative rotational position. 9. The relative rotation position detecting device according to claim 8, wherein 10. The first and second magnetic response members,
It is formed of a flat plate-shaped member having a plurality of slits formed at predetermined intervals in the rotation direction, and the magnetic coupling to the coil unit is performed by the overlapping state of the slits of the respective magnetic response members according to the relative rotation position. The relative rotational position detecting device according to claim 1, wherein the relative rotational position detecting device changes. 11. A relative rotation position detection device for detecting a relative rotation position of first and second shafts which are relatively rotatable, wherein at least one coil excited by an AC signal is arranged. And a first and a second magnetic responsive member disposed on the first and second shafts, which are magnetically coupled to the coil portion, and correspond to the relative rotational position. The relative position of the first and second magnetic response members changes, and an output corresponding thereto is generated from the coil unit.
It is formed of a flat plate-shaped member having a plurality of slits formed at predetermined intervals in the rotation direction, and the magnetic coupling to the coil unit is performed by the overlapping state of the slits of the respective magnetic response members according to the relative rotation position. A relative rotational position detecting device comprising a variable one. 12. The sensor according to claim 1, wherein the coil unit includes one sensor coil that is excited by an AC signal, and a relative position of the first and second magnetic response members is changed according to the relative rotation position. And the impedance of the sensor coil changes in response to the change. The temperature compensation coil connected in series to the sensor coil, and a connection point between the sensor coil and the temperature compensation coil, 12. The relative rotation position detecting device according to claim 11, further comprising a circuit for extracting an output signal of the sensor coil that changes based on a change in impedance of the sensor coil. 13. A circuit for generating a predetermined reference voltage composed of an AC signal, at least two AC output signals having a predetermined amplitude function as an amplitude coefficient, calculating an output signal of the coil unit and the reference voltage. 12. An arithmetic circuit for generating, wherein said periodic amplitude function of each of said AC output signals further differs by a predetermined phase in its periodic characteristic.
Or the relative rotation position detection device according to 12. 14. A circuit for generating the reference voltage, comprising:
And a second reference voltage, wherein the arithmetic circuit uses the output voltage of the coil unit and the first and second reference voltages to perform a first first arithmetic operation and a second arithmetic operation.
Are respectively generated to generate a first AC output signal having a first amplitude function as an amplitude coefficient and a second AC output signal having a second amplitude function as an amplitude coefficient. The relative rotational position detecting device according to claim 3 or 13. 15. The first and second reference voltages are used as the first and second AC output signals in the first and second AC output signals.
The first and second reference voltages are varied to determine the correspondence between the specific phase section and the relative position change range by varying the first and second reference voltages. 15. The relative rotational position detecting device according to claim 14, wherein the relative rotational position detecting device is variable. 16. A circuit for generating the reference voltage includes a first circuit including two coils connected in series so that an AC signal is applied, and a second circuit connected in series so that an AC signal is applied. A second circuit including two coils, extracting the first reference voltage from the connection point of the coil of the first circuit, and extracting the second reference voltage from the connection point of the coil of the second circuit. 16. The relative rotational position detecting device according to claim 14, wherein the relative rotational position detecting device is taken out. 17. The two coils connected in series have a magnetic core, and by adjusting the arrangement of the magnetic core with respect to each of the two coils, the impedance of the coil is adjusted. 17. The relative rotational position detecting device according to claim 16, wherein a level of a reference voltage extracted from a connection point of the coil can be adjusted.