JPH03249529A - torque sensor - Google Patents

Abstract

PURPOSE:To improve the torque measurement accuracy with simple structure by collecting a magnetic flux flow passing through a 1st and a 2nd pickup path by a magnetism collection member when a 1st shaft is twisted and displaced, and making the magnetic flux flow in a detecting element concentrically. CONSTITUTION:When the 1st shaft 1 is applied with a turning force in its circumferential direction A, the gap space from magnetic bodies 5a and 5b to magnetic path pieces 10a and 10b becomes large. The gap space from the magnetic bodies 5a and 6b to magnetic path pieces 10a and 10b becomes small to the contrary. Consequently, one magnetic field becomes intenser than the other magnetic field and the extent is proportional to the angle of a twist applied in the direction A. For example, the direction of the magnetic field applied to a Hall element 13 with the turning force in the direction A is regarded as a plus direction and the output of the element 13 is so set that the output voltage is positive, thereby properly detecting the magnitude and direction of generated torque and stationary torque.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a torque sensor, and particularly to a torque sensor that accurately measures rotational torque in a non-contact manner.

BACKGROUND OF THE INVENTION Conventional torque sensors of this type that measure rotational torque in a non-contact manner are known, for example, from Japanese Patent Laid-open No. 6, filed by the present applicant.
The one described in Japanese Patent No. 1-158433 is known.

To explain the outline based on FIG. 5, this torque sensor 30 connects a first shaft 31 and a second shaft 32 through a small diameter portion so as to be relatively torsionally displaceable.
A predetermined number of magnetic bodies 33 and 34 are attached to the outer periphery of the shaft 31 so that the polarities are arranged alternately in the circumferential direction, and a magnetic flux is applied to the second shaft 32 from an intermediate position between the adjacent magnetic bodies 33 and 34. A first pickup path 35 and a second pickup path 36 are provided to guide the magnetic material 33 to form a magnetic path from one magnetic material 33 to another magnetic material 34. A pair of magnetic detection elements 37 and 38 facing this magnetic path and detecting changes in the magnetic flux flowing through the magnetic path are provided at 1800 angular positions with respect to the axis of the first shaft 31. When the first shaft 31 is torsionally displaced with respect to the second shaft 32, the N pole approaches either the first pin pickup path 35 or the second magnetic path 36, thereby causing the first pin pickup path 35 to approach either side of the first pin pickup path 35 or the second magnetic path 36. The amount of magnetic flux flowing through the second pickup paths 35 and 36 changes, and from this change in magnetic flux, the torsional displacement of the first shaft 31 with respect to the second shaft 32 can be detected without contact.

By the way, in such a conventional torque sensor 30,
As described above, the first shaft 3 is
1 is torsionally displaced, for example, as shown in FIG. 6, the magnetic path piece 40 of the inner ring 39 on the first shaft 31 side
and the N pole of one of the magnetic bodies 33 and 34 on the second shaft 32 side are close to each other, and the magnetic flux flowing out from the N pole or the gap between the N pole and the magnetic path piece 4Q The magnetic flux flows from the inner ring 39 to the magnetic detection element 3738 and the outer ring 41 through the space and through the magnetic path piece 40 that constitutes the second pickup path 36, but the magnetic flux flow from the magnetic path piece 40 to the inner ring 39 is Not evenly distributed.

Therefore, the outer circumference of the inner ring 39 and the magnetic detection element 3
There is a possibility that the magnetic flux density becomes non-uniform at the air gear joint points C and D on the outer periphery of the outer ring 41 sandwiching 7.38, leading to a decrease in measurement accuracy by the magnetic detection element.

Therefore, in the conventional method, in addition to the pair of magnetic detecting elements 37 and 38 for torque detection, which are located at an angle of 1800 degrees relative to the axis of the first shaft 31, a pair of magnetic detecting elements 37 and 38 for averaging correction are used. The detection elements 42 and 43 are
They are arranged at different positions facing the axis of the shaft 31 at different angles of 180°, thereby averaging and correcting the density of the magnetic flux flowing out from the N pole of the magnetic body 33 and flowing into the second pickup path 36. It looks like this.

Problems to be Solved by the Invention However, in the conventional torque sensor 30, the non-uniform state of magnetic flux density generated at the N pole of the magnetic body 33 is averaged and corrected using the magnetic detection elements 42 and 43. As a result, the number of magnetic detection elements used increases and the magnetic flux circuit becomes complicated. As a result, manufacturing operations and maintenance management become complicated, and costs are forced to rise.

Means for Solving the Problems The present invention was devised in view of the above-mentioned conventional situation, and
The structure is basically similar to the conventional structure described above, but in particular, the magnetic detection element for torque detection has the first. The present invention is characterized in that a magnetic flux collecting member is provided to collect the magnetic flux flowing through both or either side of the second pickup path.

Operation When torsional displacement occurs in the rotational direction of the first shaft, magnetic flux flows with different densities that have passed through the first pickup path or the second pick-up path are efficiently collected by the magnetic collecting member and sent to the magnetic detection element. Concentrated inflow. Therefore, such magnetic flux is averaged and corrected before reaching the magnetic detection element,
Not only does torque measurement accuracy improve, but because a magnetic flux collecting member made of a material through which lines of magnetic force easily pass is simply provided without using a magnetic detection element for averaging correction as in the past, magnetic flux circuits, etc. The structure of is extremely simplified, and
Manufacturing costs can be reduced.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First, the configuration of the torque sensor according to the present invention will be explained based on FIG. 4. That is, 1 in the figure is a first shaft, and the first shaft 1 is connected to a second shaft 3 via a small diameter part 2 to slightly reduce torsional rigidity, and is indicated by A and B in the figure. The rotational force in the circumferential direction of the first shaft 1 is transmitted to the second shaft 3 via the small diameter portion 2. Also, the outer peripheral surface 3a of the second shaft 3 is molded so as to wrap around the small diameter portion 2. A tip end 4a of a cylindrical mold member (non-magnetic material) 4 is fitted and fixed, and the mold member 4 is connected to a pickup member 7 and a Hall element 13, which will be described later.
14, etc., and form a torque detection mechanism 21. On the other hand, a donut-shaped magnetic body embedded part 4b is formed on the other end side of the mold member 4, and the magnetic body embedded part 4b has an end surface 4C perpendicular to the axial direction. 8 magnetic bodies 5a are arranged so that the north pole faces the end face 4C, and 8 magnetic bodies 5b are arranged so that the south pole faces the end face 4C, which are arranged alternately in concentric circles and at equal intervals. It is arranged. Further, the other end of each magnetic body 5a, 5b is connected to an annular common ring 6, and the common ring 6 is connected to each magnetic body 5a, 5b.
It forms part of a closed loop magnetic path for the magnetic field emitted from the magnetic field.

The common ring 6 and each of the magnetic bodies 5a and 5b are buried within the magnetic body embedding section 4b, and are formed integrally with the magnetic body embedding section 4b made of a non-contact material.

On the other hand, on the outer peripheral surface 1a of the first shaft 1 on the small diameter portion 2 side,
The disk-shaped pickup member 7 facing the end surface 4C and having a small gap with the end surface 4C is fitted and fixed, and an outer ring 8 is provided on the input side end surface 7a of the pickup member 7 in circumferential contact with the end surface 7a. and inner ring 9
and is provided. Further, on the end surface 7b of the pickup member 7 facing the end surface 4C, there is a magnetic path piece [Oa] and a magnetic path piece 1 which becomes a magnetic path by receiving the magnetic force from the magnetic body 5a or 5b.
0b corresponds one-to-one with the magnetic bodies 5a and 5b, eight pieces are arranged alternately on a concentric circle and at equal intervals, The pieces 10b are respectively connected to the inner ring 9.

The magnetic path piece 10a and the outer ring 8 constitute a first pickup path 11, and the magnetic path piece Job and the inner ring 9 constitute a second pickup path 12. Here, the common ring 6, the magnetic path pieces 10a and 10b, the outer ring 8, and the inner ring 9 are made of a material through which lines of magnetic force easily pass, such as permalloy or ferrite.
The magnetic force emitted from a and 5b is guided to the outer ring 8 and the inner ring 9 via the magnetic path pieces 10a and lOb. Further, the magnetic path piece 10a and Job are connected to the magnetic body 5.
Pick-up member 7 made of non-magnetic material like a and 5b
The magnetic body 5a or 5b is integrally formed within the magnetic path piece 10a during steady state (that is, when the torque is O).
and IOb. Therefore, a gap space 12A (not shown) from the magnetic body 5a to the magnetic path piece 10a and a gap space QB (not shown) from the magnetic body 5a to the magnetic path piece 10b.
are equal to each other, and similarly from the magnetic body 5b to the magnetic path piece 10b
The gap space QA from 5b to the magnetic path piece 10a is equal to the gap space QI from 5b to the magnetic path piece 10a. Therefore, when a rotational force in the circumferential direction A (or B) is applied to the first shaft 1, the cap spaces QA and 12m change by a predetermined amount in accordance with the rotational force. Furthermore, between the outer ring 8 and the inner ring 9 described above, there is a magnetic field that is not in contact with these rings or the pickup member 7 and is applied from the outer ring 8 to the inner ring 9 (or from the inner ring 9 to the outer ring 8). A first Hall element 13, which is a magnetic detection element, is arranged at a right angle, and a second Hall element 14, which is a magnetic detection element, is arranged at a position facing the first Hall element 13 at an angle of 180°. . Also, these first. Second Hall element 13.
14 are general elements that generate an output voltage proportional to the strength of a magnetic field, and are each fixed to a printed circuit board 15 with an adhesive or the like.

The printed circuit board 15 is rotatably fitted to the first shaft 1 via the support member 15a, and also includes a member (
(not shown) is provided.

Then, the first Hall element 13 and the second Hall element 14
As shown in FIG. 1, magnetic flux collecting members 16 and 17 are provided to collect the magnetic flux flowing through the first pickup path 11 and the second pickup path 12, respectively. This magnetic collecting member 16
．． Reference numeral 17 is made of a material such as permalloy through which lines of magnetic force easily pass, and is formed into a substantially square shape, and is fixed to each Hall element 13, 14 and protrudes in the radial direction. Bases 16a and 17a;
A pair of arcuate magnetic flux collectors 16b, 16c, 17b, and 17c are integrally provided at both ends of each of the magnets 6a, 17a. Each of the magnetic collecting parts 6b to 17C is arranged in a non-contact state with respect to the outer ring 8 and the inner ring 9, and extends in the left and right circumferential direction around the base parts 16a and 17a, and connects to the magnetic bodies 5a and 5b. It is arranged so as to straddle and cover both the dense part X with high magnetic flux density generated at the air gap junction points C and D with the magnetic path pieces 10a and 10b, and the thin coarse part Y adjacent to the dense part X. There is.

Next, the operation of this embodiment will be explained. That is, in a steady state where no torque is applied, the gap space 12A,
Since 12B are equal to each other, for example, the magnetic field HA that reaches from the N pole of the magnetic body 5a to the Hall element 13 via the gear space Q, A, the magnetic path piece 10a, and the outer ring 8, and the magnetic body 5a
From the N pole of gear gear space ρ8. The strength of the magnetic field H6 reaching the Hall element 13 via the magnetic path piece 10b and the outer ring 8 is equal in strength, canceling each other out, and no torque is detected.

On the other hand, when a rotational force is applied in the circumferential direction A as shown in FIG.
The gear knob space from the magnetic body 5b to the magnetic path piece 10b becomes larger, and conversely, the gap space QB from the magnetic body 5a to the magnetic path piece 10b and the gear knob space from the magnetic body 5b to the magnetic path piece 10b become larger. The gap space QB up to 10a is small. Therefore, along with this, one of the magnetic fields HB
on the other hand, becomes larger than the magnetic field HA, and its degree is A
It is proportional to the magnitude of the twist angle applied in the direction. For example, if the direction of the magnetic field applied to the Hall element 13 by the rotational force in the A direction is in the positive direction, and the output of the Hall element 13 is set so that the output voltage is a positive value, the magnitude and direction of the generated torque and Static torque can be appropriately detected. Also, when rotational force is applied in the same circumferential direction B, one magnetic field H is generated.

becomes larger than the other magnetic field HB, and it is possible to detect torque in the opposite direction to that in the above case.

In addition, here, for example, the magnetic flux flow passing through the first pickup path II, that is, the magnetic flux flow from the magnetic path piece 10a to each Hall element 13. Each magnetic flux is collected by the magnetic collecting parts 16b and 17b of the magnetic collecting members 16 and 17, and then the base 1
6a, 17a and flow into each Hall element 13, 14.

In this way, the magnetic flux that has flowed into the outer ring 8 is collected by the magnetic collecting members 16, 17, and the density is averaged and corrected, so that measurement errors due to the dense portions X and coarse portions Y can be made as small as possible. Therefore, not only the accuracy of torque measurement by each Hall element 13, 14 is improved, but also the magnetism collecting member 16 is simply attached to each Hall element 13, 14 without using a magnetic detection element for averaging correction as in the past. Since only .17 is provided, the magnetic flux circuit is simplified, and manufacturing work and maintenance management become easier. Furthermore, since the magnetic flux collecting members 16 and 17 are cheaper than the Hall elements, manufacturing costs can be reduced.

FIG. 2 shows a second embodiment of the invention, in which:
Each magnetic flux collecting part 18b is formed by bending the magnetic flux collecting member 18 into a planar substantially crank shape, and has magnetic flux collecting parts 18b at both ends of the base 18a.
The portions 18b extend alternately in the circumferential direction so as to cover the dense portions X and rough portions Y of the magnetic flux flow of the outer ring 8 and the inner ring 9.

Therefore, in this embodiment as well, the magnetic flux that has passed through the magnetic flux collecting member 18 or each pickup path 11.12 is collected and intensively flows into the Hall element 13.14, so that the same effect as in the first embodiment can be obtained. In addition, since the structure of the magnetic flux collecting member 18 is relatively simple, manufacturing work becomes easy.

FIG. 3 shows a third embodiment of the present invention, in which the Hall elements 13 provided along the radial direction of each ring 8, 9 are bent in a crank shape along the circumferential direction. A magnetic member 19 is fixed. That is, the magnetic flux collecting member 19 is
The base 19a is fixed to the Hall element 13 along the circumferential direction, and magnetic flux collectors 19b are provided on both sides of the base 19a.
, 1.9b are continuously arranged across the dense portions X and coarse portions Y of the outer ring 8 and the inner ring 9.

Therefore, this embodiment also applies to the first example. The same effects as in the second embodiment can be obtained, and the structure of the magnetic flux collecting member 19 is further simplified, resulting in even better manufacturing workability.

In addition, in each embodiment, magnetic flux collecting members 16, 17, 18, 19
By providing this, it becomes possible to set a large air gap between the outer ring 8 and the inner ring 9. Therefore, this large air gap prevents magnetic flux from leaking outside the Hall element 13.14, and the collection efficiency by the magnetic collecting member 16.17 improves accordingly, allowing the concentration of magnetic flux to the Hall element 13.14. This will further improve torque measurement accuracy.

In each of the embodiments, the magnetic collecting parts of the magnetic collecting member are provided on both the outer ring 8 side and the inner ring 9 side, but they may also be provided only on either the ring 8 or 9 side on the blade side. It is possible.

Effects of the Invention As is clear from the above description, according to the torque sensor according to the present invention, in particular, the magnetic detection element includes a collector that collects magnetic flux flowing through both or one side of the first pickup path and the second pickup path. Because the magnetic member was provided, the first. Second
It becomes possible to concentrate the magnetic flux flowing from the pickup path into the magnetic detection element for torque detection, and it is possible to sufficiently reduce measurement errors due to changes in magnetic flux density. As a result,
Not only does the accuracy of torque measurement by the magnetic detection element improve, but since the magnetic detection element for averaging correction as in the prior art is not required, the number of parts can be reduced and the magnetic flux circuit can be simplified. Therefore, manufacturing work and maintenance management become easier, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of main parts showing a first embodiment of the torque sensor according to the present invention, FIG. 2 is an enlarged view of main parts showing a second embodiment of the invention, and FIG. 3 is a third embodiment of the present invention. An enlarged view of the main part showing an example,
FIG. 4 is an exploded perspective view showing the torque sensor of the present invention, and FIG.
The figure is an enlarged view of a main part of a conventional torque sensor, and FIG. 6 is an explanatory diagram showing magnetic flux flow in the conventional torque sensor. ■...First shaft, 2...Small diameter portion, 3...Second shaft, 5a, 5b...Magnetic material, 10a, 10b...
-Magnetic path piece, 11...first pickup path, 12...
Second pickup path, 1.3.14...Hall element (
magnetic detection element), 16.17, 18.19...magnetic collecting member. 1st Numaft Horseman, 5b m, Noj, Nama, I〉)S; 16.171B, 19 ---- Fruit aiming country η Fig. 2 Fig. 3 Fig. 5 Fig. 6

Claims (1)

[Claims] (1) a first shaft and a second shaft that are connected to allow relative torsional displacement; a predetermined number of magnetic bodies attached to the outer periphery of the one shaft so that the polarities are arranged alternately in the circumferential direction; a first pickup path and a second pickup path that are attached to the other shaft so as to guide magnetic flux from an intermediate position between the adjacent magnetic bodies to form a magnetic path from one magnetic body to another; In a torque sensor equipped with a magnetic detection element that detects a change in magnetic flux flowing through each magnetic path, the magnetic flux flowing through both or one side of the first pickup path and the second pickup path is collected in the magnetic detection element. A torque sensor characterized by being provided with a magnetism collecting member.