JPH11252947A - Vibration actuator - Google Patents

Abstract

(57) [Problem] In a conventional vibration actuator, abrasion powder is generated with an increase in driving time, and the vibrator and the relative motion member are stuck and noise is generated. SOLUTION: The vibrator 11 is provided on the vibrator 11 by generating a pressing force between the vibrator 11 and a relative motion member 21 which generates relative motion between the vibrator 11 and the relative motion member 21. And a pressurizing mechanism 31 that presses the vibrator 11 and the relative motion member 21 through the provided driving force extracting portions 12a and 12b, and the pressing mechanism 31 slides on the driving force extracting portions 12a and 12b. The vibration actuator 10 has a pressing force variable function of reducing the pressing force when the sliding resistance increases in which the dynamic resistance increases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator, and more specifically, to a vibrator, a relative motion member which generates a relative motion between the vibrator, and a pressurizing member for pressurizing the two members. The present invention relates to a vibration actuator having a mechanism.

[0002]

2. Description of the Related Art A vibration actuator using a so-called deformed mode degenerate type vibrator that generates two different vibrations simultaneously is disclosed in, for example, "Fifth Electromagnetic Force-Related Dynamic Symposium Proceedings", page 393. And disclosed by Yoshiro Tomikawa.

FIG. 18 is a perspective view showing a vibration actuator 1 having a vibrator 2 disclosed in this collection of lecture papers. FIG. 19 is an explanatory diagram showing an example of two vibration waveforms generated in the vibrator 2.

As shown in FIG. 18, a vibrator 2 includes an elastic body 3 and an electromechanical transducer 4 for converting electric energy into mechanical energy (hereinafter, a “piezoelectric body” will be described as an example). .

The elastic body 3 is formed in a rectangular plate shape from a metal material having a large resonance sharpness. The dimensions of the elastic body 3 are set such that the natural frequencies of the generated longitudinal vibration L1 and bending vibration B4 are substantially the same.

A piezoelectric body 4 is attached and attached to one plane of the elastic body 3. The piezoelectric body 4 has four areas including input sections 4a and 4b to which two-phase drive voltages of A-phase and B-phase are applied, a detection section 4p for monitoring the vibration state of the vibrator 2, and a ground section 4g. Are continuously formed. 4 areas 4
For example, silver electrodes 5a, 5b, 5p and 5g are mounted on the respective surfaces of a, 4b, 4p and 4g apart from each other.

[0007] The other plane of the elastic body 3, in the longitudinal direction of the vibrator 2, generated bending vibration B 4 of 4
Outer antinode positions l ₁ and l ₄ of the antinode positions l ₁ , l ₂ , l ₃ and l ₄ are provided with two driving force output portions 3 in a protruding manner.
a, 3b are formed. Sliding members 7a and 7b mainly composed of a resin material such as a polymer material or a metal material are adhered to the bottom surfaces of the driving force extracting portions 3a and 3b by, for example, an epoxy resin adhesive. Through these sliding members 7a and 7b, the plate-shaped relative motion member 6 is brought into pressure contact with an appropriate pressing force.

In this state, the input units 4a and 4b are driven by high-frequency driving whose frequency is substantially equal to the natural frequency of each of the longitudinal vibration L1 and bending vibration B4 generated in the elastic body 3 and whose phase is shifted by (π / 2). Voltages V _A and V _B are applied, respectively. Then, as shown in FIG. 19, the elastic body 3 has a primary longitudinal vibration L1 vibrating in the longitudinal direction of the vibrator 2 and a fourth-order bending vibration B4 vibrating in the thickness direction of the vibrator 2. Occurs at the same time. Longitudinal vibration L1 and bending vibration B generated in elastic body 3
4 and an elliptical motion that is periodically displaced in an elliptical shape is generated on the bottom surface of each of the driving force output portions 3a and 3b. As a result, the vibrator 2 performs a linear relative motion in the longitudinal direction of the vibrator 2 between the vibrator 2 and the relative motion member 6 that is brought into pressure contact via the sliding members 7a and 7b. Therefore, in the vibration actuator 1, it is necessary to bring the vibrator 2 and the relative motion member 6 into pressurized contact with an appropriate pressing force.

Therefore, the applicant of the present invention has previously described, for example,
-140374, etc., proposes a pressurizing mechanism that presses the vibrator 2 toward the relative motion member 6 at one position at the center of the vibrator in the longitudinal direction (position C in FIGS. 18 and 19). did.

This pressurizing mechanism presses the vibrator 2 toward the relative motion member 6 using, for example, a spring force generated by a coil spring. Therefore, the generated pressure F
As shown in the graph of FIG.
Regardless of the position of the transducer 2 with respect was always constant value between 50 gf / mm ² approximately.

[0011]

However, according to the study of the present inventors, in the vibration actuator 1, the sliding members 7a and 7b gradually wear as the driving time increases, and the accumulated wear is increased. It has been found that the powder has a problem that the dynamic characteristics of the vibration actuator 1 are significantly reduced.

For example, when the relative motion member 6 is fixed and the vibrator 2 is linearly reciprocated with respect to the relative motion member 6, the vibrator 2 moves in the vicinity of the change point of the motion direction as the driving time increases. Wear powder gradually accumulates on the surface. If the vibrator 2 is stopped for a predetermined time in the vicinity of the movement direction change point after the long-time driving, the vibrator 2 and the relative motion member 6 are fixed by the intervening wear powder and cannot be restarted.

[0013] Even if such sticking does not occur, an abnormal noise is generated along with the passage of the vibrator 2 in the vicinity of the movement direction conversion point. Therefore, the quietness, which is one of the features of the vibration actuator 1, is significantly impaired.

Here, an object of the present invention is to remarkably suppress the generation of abrasion powder due to an increase in driving time, thereby preventing both the sticking of the vibrator and the relative motion member and the generation of abnormal noise. Another object of the present invention is to provide a vibration actuator that can be driven stably for a long period of time.

[0015]

Means for Solving the Problems The present inventors have proposed a sliding member 7.
Attention was paid to the pressing force between the vibrator 2 and the relative motion member 6, which is one of the factors affecting the wear of the members 7a and 7b. The inventors have found that the above problem can be solved by temporarily reducing the pressing force when abrasion powder is easily generated, and completed the present invention.

According to a first aspect of the present invention, a vibrator is provided on a vibrator by generating a pressing force between the vibrator and the relative motion member. A pressurizing mechanism for pressurizing the vibrator and the relative motion member through the driving force take-out portion, wherein the pressurizing mechanism increases the sliding resistance generated in the drive force take-out portion. A vibration actuator having a pressing force variable function of adjusting the pressing force in the above.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the time when the sliding resistance increases is a time when the direction or the speed of the relative motion is changed.

According to a third aspect of the present invention, in the vibration actuator according to the second aspect, the pressing force is a first pressing force generated near the time when the direction of the relative motion is changed, and the pressing force is generated when the direction of the relative motion is changed. And a second pressurizing force generated larger than the first pressurizing force outside the vicinity.

According to a fourth aspect of the present invention, in the vibration actuator according to the third aspect, the first pressing force changes so as to be minimum when the direction of the relative motion is changed.

According to a fifth aspect of the present invention, in the vibration actuator according to any one of the first to fourth aspects, the pressing mechanism presses the vibrator or the relative motion member. And a piston connected to the pressurizing unit, a cylinder accommodating the piston, and a gas supply system that changes the pressure acting on the piston by supplying gas to or discharging gas from the cylinder, A control device for controlling the gas supply system based on the information on the relative motion.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a vibration actuator according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, an ultrasonic actuator using an ultrasonic vibration region will be described as an example of the vibration actuator.

FIG. 1 is a sectional view showing the structure of an ultrasonic actuator 10 according to this embodiment. FIG. 2 is a perspective view showing the ultrasonic actuator 10 in a partially see-through state.

The ultrasonic actuator 10 of the present embodiment
Includes a vibrator 11, a relative motion member 21 that generates relative motion between the vibrator 11, and a pressure mechanism 31 that presses the vibrator 11 and the relative motion member 21 into contact. Less than,
These components will be described separately.

[Vibrator 11] The vibrator 11 includes an elastic body 12
And a piezoelectric body 13 mounted on one plane of the elastic body 12.

The elastic body 12 is made of SUS30 in this embodiment.
4 form a rectangular flat plate. The dimensions of each part of the elastic body 12 are set such that the natural frequencies of the generated primary longitudinal vibration L1 and the generated quaternary bending vibration B4 substantially coincide with each other. The elastic body 12 may be formed of a metal material having a large resonance sharpness, such as steel, stainless steel, phosphor bronze, or an elinvar material, other than stainless steel.

On one flat surface of the elastic body 12, a piezoelectric body 13 to be described later is mounted, for example, by bonding. Further, two grooves in the width direction of the elastic body 12 are provided on the other plane of the elastic body 12 at a predetermined distance from each other in the relative movement direction (the left-right direction in FIG. 1). A sliding member having a rectangular cross-sectional shape is fitted into these grooves, adhered with an epoxy-based adhesive, and mounted in a protruding manner.

The sliding material is used as the driving force take-out portion 12.
Functions as a and 12b. Therefore, the elastic body 12
Are driving force take-out portions 12a, 12b made of these sliding members.
Contacts the relative motion member 21 via the.

In the present embodiment, the sliding material is a material obtained by mixing 15% by weight of glass fiber and 5% by weight of molybdenum disulfide in a resin having PTFE as a matrix (trade name: Polyflon, Daikin Industries, Ltd.). ).

FIG. 3 shows a longitudinal vibration L 1 generated in the vibrator 11.
It is explanatory drawing which shows bending vibration B4. The driving force output members 12a, 12b, as shown in FIG. 3, four loop position l ₁ to l ₄ fourth-order bending vibration B4 generated in the elastic member 12
Are provided at positions corresponding to the antinode positions l ₁ and l ₄ located on the outer side. In addition, the driving force extraction units 12a and 12b
Need not belly position l _1, l ₄ bending vibration B4 is positioned to match exactly, and may be in the vicinity of the antinode position.

In the present embodiment, the piezoelectric body 13 is composed of a thin plate-shaped piezoelectric element made of PZT (lead titanium zirconate, registered trademark). The piezoelectric body 13 has input areas 13a and 13c in which an A-phase drive signal is input, and input areas 13b and 13d in which a B-phase whose phase is shifted by (π / 2) from the A-phase is input. It is formed. Each input area 13a-1
3d, as shown in FIG. 3, is partitioned by five nodal position n ₁ ~n ₅ bending vibration B4 generated in the elastic member 12 4
Formed in one area. That is, each input region 13a~13d be deformed by input of the driving signal are both, because does not cross the nodal position n ₁ ~n ₅ is a fixed point, the deformation of the input region 13a~13d knots position n ₁ ~ n lack of inhibition by _5. Therefore, each of the input areas 13a to 13
The electric energy input to d is the elastic body 1 at the maximum efficiency.
2 is converted into mechanical energy.

At the nodal positions n ₂ and n ₄ of the bending vibration B4, detection regions 13p and 13p 'for outputting electric energy by the longitudinal vibration L1 generated by the vibrator 11 are provided in a semicircular shape. Thereby, the longitudinal vibration L generated by the vibrator 11
1 is detected.

Each of the input areas 13a to 13d and each of the detection areas 1
3p and 13p 'mean that each surface is a silver electrode 15a.
~ 15d, 15p, 15p '. As a result, it is possible to input a drive signal to each of the input regions 13a to 13d independently, and to output a detection signal independently from each of the detection regions 13p and 13p '.

In this embodiment, the vibrator 11 is formed so as to be point-symmetric about the center of the plane of the vibrator 11. As a result, the elliptical motions generated in the driving force extracting portions 12a and 12b can be made substantially the same shape, and a driving difference (left-right difference) due to the reversal of the relative motion direction hardly occurs.

FIG. 4 is a block diagram showing the drive control circuit 20 of the vibrator 11. The oscillator 16 oscillates a signal having a frequency corresponding to each of the longitudinal vibration L1 and the bending vibration B4 of the vibrator 11. The output of the oscillator 16 is branched, and one of the outputs is amplified by the amplifiers 17a and 17c, and then, as an A-phase voltage, the silver electrodes 1 of the input regions 13a and 13c
Input to 5a and 15c. The other branched output is shifted by (π / 2) from the A-phase voltage by the phase shifter 18 to become the B-phase voltage, and then the amplifiers 17 b and 17.
d, the silver electrodes 15b, 1b of the input areas 13b, 13d
Input to 5d.

The control circuit 19 includes detection areas 13p and 13p.
The output voltage of p 'is input. Compared to a preset reference voltage, the frequency is lowered when the output of the detection areas 13p and 13p 'is smaller, while the frequency is increased when the output of the detection areas 13p and 13p' is larger. Next, the oscillator 16 is controlled. Thereby, the vibration amplitude of the vibrator 11 is maintained at a predetermined magnitude.

In this manner, the input area 1 of the piezoelectric body 13
An A-phase drive signal having a frequency corresponding to the natural frequency of each of the longitudinal vibration L1 and the bending vibration B4 is input to 3a and 13c, and A is input to the input regions 13b and 13d.
A drive signal of the B phase having a phase difference of (π / 2) is input. Then, as shown in FIG.
The first-order longitudinal vibration L1 and the fourth-order bending vibration B4 occur simultaneously. These vibrations are combined, and the driving force output unit 12
Elliptic motion occurs at a and 12b.

FIG. 5 is an explanatory diagram showing a state in which the primary longitudinal vibration L1 and the fourth-order bending vibration B4 are combined to generate elliptic motion in the driving force output portions 12a and 12b with time.
In FIG. 5, for convenience, each of the input areas 13a to 13a
3d are shown separated from each other.

FIG. 5A shows the state of the input signal 2 to the vibrator 11.
The temporal changes of the high-frequency voltages A and B of the phases are represented by the time t ₁ to the time t.
₉ is shown. The horizontal axis in FIG. 5A indicates the effective value of the high-frequency voltage. FIG. 5 (B) shows a state of deformation of the cross-section of the elastic body 12 are shown for the time t ₁ ~ time t ₉ the temporal change of the bending vibration B4 generated in the vibration element 11. FIG. 5 (C)
Shows the state of the change in the cross section of the elastic body 12, and the vibrator 11
Time t ₁ the temporal variation of the longitudinal vibration L1 occur to t
₉ is shown. Further, FIG. 5 (D) shows the time t ₁ ~ time t ₉ the driving force output portion 12a, a temporal change of the elliptical motion generated 12b of the vibrator 11.

At time t ₁ , as shown in FIG. 5A, the high-frequency voltage A generates a positive voltage, and the high-frequency voltage B generates the same positive voltage. As shown in FIG. 5B, the bending vibrations B4 due to the high-frequency voltages A and B cancel each other, and the mass points Y1 and Z1 both have zero amplitude. FIG.
As shown in (C), the longitudinal vibration L due to the high-frequency voltages A and B
1 occurs in the direction of extension. As indicated by arrows, both the mass points Y2 and Z2 show the maximum extension centering on the node position X (node position n ₃ in FIG. ₃ ). As a result, FIG.
As shown in (D), the longitudinal vibration L1 and the bending vibration B4 are combined, the combination of the motions of the mass points Y1 and Y2 becomes the motion of the mass point Y, and the combination of the motions of the mass points Z1 and Z2 is combined with the motion of the mass point Z. Become.

At time t ₂ , as shown in FIG. 5A, the high-frequency voltage A generates a positive voltage, and the high-frequency voltage B becomes zero. As shown in FIG. 5B, a bending vibration B4 due to the high-frequency voltage A occurs, the mass point Y1 oscillates in the negative direction,
The mass point Z1 oscillates in the positive direction. Further, as shown in FIG. 5 (C), longitudinal vibration L1 is generated by high frequency voltage A, shrinks than when the point Y2 and point Z2 is a time t _1. As a result, as shown in FIG. 5D, the longitudinal vibration L1 and the bending vibration B4
Are synthesized, and both the mass points Y and Z rotate counterclockwise from the time t ₁ .

At time t ₃ , as shown in FIG. 5A, the high-frequency voltage A generates a positive voltage, and the high-frequency voltage B generates the same negative voltage. As shown in FIG. 5 (B), high frequency voltage A, vibration B4 bending by B are amplified are synthesized, point Y1 is amplified from at time t ₂ in the negative direction by indicating the maximum negative amplitude values. Also, point Z1 is than at time t ₂ is amplified in the positive direction indicating a maximum positive amplitude value. Also, as shown in FIG. 5C, the longitudinal vibrations L1 due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z2
Returns to the original position. As a result, the longitudinal vibration L1 and the bending vibration B4 are synthesized as shown in FIG.
Are both, than at time t ₂ is rotated and moved to the left-handed.

At time t ₄ , as shown in FIG. 5A, the high frequency voltage A becomes zero and the high frequency voltage B generates a negative voltage. As shown in FIG. 5 (B), the vibration B4 bending by high frequency voltage B is generated, and decreased amplitude than when point Y1 is a time t _3, the amplitude than at point Z1 also time t ₃ is reduced . Further, as shown in FIG. 5C, a longitudinal vibration L1 due to the high frequency voltage B is generated, and both the mass points Y2 and Z2 contract. As a result, the longitudinal vibration L1 and the bending vibration B4 are synthesized as shown in FIG.
Together, the rotational movement to the left-handed than at time t _3.

[0043] At time t _5, as shown in FIG. 5 (A), the high frequency voltage A generates a negative voltage, high frequency voltage B is the same negative voltage. As shown in FIG. 5B, the bending vibrations B4 caused by the high-frequency voltages A and B cancel each other, and the amplitudes of the mass points Y1 and Z1 are both zero. FIG.
As shown in (C), the longitudinal vibration L due to the high-frequency voltages A and B
1 occurs in the contracting direction. Both the mass points Y2 and Z2 show the maximum contraction around the node position X as indicated by the arrows. As a result, the the longitudinal vibration L1 and the bending vibration B4 is synthesized as shown in FIG. 5 (D), the mass points Y, Z are both rotated move further counterclockwise from their respective positions at the time t _4.

From time t ₆ to time t ₉ , similarly to time t ₁ to time t ₅ , the longitudinal vibration L 1 and bending vibration B 4
As a result, as shown in FIG. 5D, the mass points Y and Z rotate clockwise. In this manner, counterclockwise elliptical motions shifted by a half cycle are generated in the driving force extracting portions 12a and 12b of the vibrator 11, respectively. Due to the generated elliptical motion, a relative motion is generated between the pressure-contacting relative motion member 21 and the relative motion member 21.

In order to reverse the relative movement direction,
The B-phase drive signal is (-π / 2) with respect to the A-phase drive signal.
May be set so as to have the following phase difference. In the present embodiment, the vibrator 11 is configured as described above.

[Relative Motion Member 21] As shown in FIGS. 1 and 2, the relative motion member 21 is disposed in contact with the driving force output portions 12a and 12b of the vibrator 11.

In the present embodiment, the relative motion member 21 is formed in a flat plate shape of stainless steel, and is fixedly installed as shown in FIG. 8 described later. Thus, the elliptical motion generated in the driving force output portions 12a and 12b of the vibrator 11 causes relative motion with the vibrator 11 in the same direction (the left-right direction in FIG. 1) as the vibration direction of the longitudinal vibration L1. .

The relative motion member 21 may be made of a copper alloy, an aluminum alloy, a polymer material or the like. In the present embodiment, the relative movement member 21 is configured as described above.

[Pressing Mechanism 31] As shown in FIGS. 1 and 2, the pressing mechanism 31 of the present embodiment is provided with a pressing portion 32 formed of a PTFE pressing rod having a conical end. Can be One end of the pressurizing portion 32 is connected to a node position n _{3 of the} vibrator 11.
Abuts the vibrator 11 on the relative motion member 21.
Press toward.

A piston 33 accommodated in a cylinder 34 is connected to the other end of the pressurizing section 32 such that the stroke direction thereof coincides with the axial direction of the pressurizing section 32. The interior of the cylinder 34 is partitioned by a piston 33 into a first chamber 35 and a second chamber 36. Cylinder 3
An air port 35 a communicating with the first chamber 35 and sucking and discharging the first chamber 35 is provided on the outer peripheral surface of the fourth chamber 4. The second chamber 36 communicates with the second chamber 36.
6 is provided with an air port 36a for performing intake and exhaust.

The compressed air is sucked and discharged using the air ports 35a and 36a. Thus, by making the pressure in the first chamber 35 higher than the pressure in the second chamber 36, a pressure for lowering the piston 33 is generated. Thereby, the pressing force by the pressing unit 32 increases. Also, the first
By making the pressure in the chamber 35 smaller than the pressure in the second chamber 36, a pressure for raising the piston 33 is generated. Thereby, the pressing force by the pressing unit 32 decreases.

A gas supply system 38 and a pressure control device 48 are connected to the air ports 35a and 36a via air tubes 37a and 37b. FIG. 6 is an explanatory diagram showing the configuration of each of the air supply system 38 and the pressure control device 48.

As shown in FIG.
a and 37b are a solenoid valve 39 and an air tube 37c.
Is connected to the electropneumatic regulator 40 via the Also,
The electropneumatic regulator 40 is connected to a pneumatic pressure source 41 via an air tube 37d. Thus, a reference air pressure amount is obtained, and an air pressure to be supplied to the cylinder 34 is generated.

Further, the electromagnetic valve 39 is provided with the pressing force control device 4.
8 is electrically connected to an I / O control unit 42 provided in the control unit 8. The solenoid valve 39 switches the pneumatic supply direction so as to supply pneumatic pressure to one of the air tubes 37a and 37b according to a signal from the I / O control unit 42.

The electropneumatic regulator 40 is connected to the D / A converter 43 provided in the pressure control device 48. The electropneumatic regulator 40 changes the amount of pneumatic pressure to be output according to the voltage signal from the D / A converter 43.

The pressure switch 44 is connected to the air tube 37
After the output of the electropneumatic regulator 40 is measured via c and converted into a voltage signal, it is output to the A / D converter 45. A /
The D converter 45 converts the voltage signal from the pressure switch 44 into numerical data, and outputs it to the controller 46.

The controller 46 includes a controller 46
Is connected to a power supply 47 as an electric supply source for operating the. The controller 46 includes an A / D converter 45 and a D / A
Is electrically connected to the converter 43 and the I / O control unit 42;
The transmission and reception of each data signal and the supply of power for operating each data signal are performed.

In the air supply system 38 and the pressure control device 48, first, numerical data on the amount of pressurization according to the driving conditions of the ultrasonic actuator 10, which is set and stored in the controller 46 in advance, is transmitted from the controller 46 to the D
/ A converter 43. D / A receiving this output
A voltage amount corresponding to the numerical data received by the converter 43 is output from the D / A converter 43 to the electropneumatic regulator 40.

The electropneumatic regulator 40 includes a D / A converter 4
The air pressure to be output is controlled and supplied to the solenoid valve 39 in accordance with the change in the amount of voltage from 3. At this time, in response to a signal from the controller 46, the I / O control unit 42 controls the electromagnetic valve 39 to switch the direction of supplying air pressure to the air tubes 37a and 37b. Thus, the vibrator 11 is appropriately pressurized by the cylinder 34 with the pressing force.

The pressure switch 44 is connected to the electropneumatic regulator 4
The output of 0, that is, the amount of air pressure applied to the cylinder 34 is measured. After converting this measurement result into a voltage quantity, A
Output to the / D converter 45. The A / D converter 45 converts the amount of voltage from the pressure switch 44 into numerical data and outputs it to the controller 46.

In the controller 46, the D / A converter 43
The amount of correction is always obtained from the difference between the numerical data output to A and the numerical data input from the A / D converter 45. Then, the obtained correction value is added to the numerical data to be output to the D / A converter 43, and is output to the D / A converter 43 again. Also,
The controller 46 changes numerical data output to the D / A converter 43 at a preset timing so as to change the amount of air pressure applied to the cylinder 34 during driving.

According to the air supply system 38 and the pressure control device 48, the amount of pneumatic pressure applied to the cylinder 34 can be automatically changed even during driving without operator intervention. In addition, by constantly measuring and feeding back the air pressure amount, the output air pressure amount can be constantly and accurately controlled.

FIG. 7 shows the drive control circuit 2 shown in FIG.
FIG. 7 is an explanatory diagram showing a connection between 0 and the air supply system 38 and the pressure control device 48 shown in FIG. 6. For example, by a position detecting means 49 constituted by a photoelectric switch or the like,
The relative position between the vibrator 11 and the relative motion member 21 is detected. The detected value is output to the drive control circuit 20 and the pressing force control device 48, and the drive control circuit 20
, Various drive control signals are output to the controller 46 of the pressing force control device 48.

As described above, in the present embodiment, by supplying gas to the cylinder 34 or discharging gas from the cylinder 34, the gas supply system 38 for changing the pressure acting on the piston 33 and the relative motion Pressure control device 48 for controlling the gas supply system 38 based on the information of
Be composed.

FIG. 8A is a top view of a driving device 50 incorporating the ultrasonic actuator 10 of the present embodiment, and FIG. 8B is a side view. FIG. 9 is similar to FIG.
FIG. 9A is a sectional view taken along the line EE in FIG. 8A or FIG.

A mounting bracket 52 is mounted annularly on the upper periphery of the cylinder 34. This driving device 50
Then, the four bolts 53 through the mounting bracket 52
Thereby, the cylinder 34 is fastened and fixed by penetrating the ceiling surface of the box-shaped casing 51. In addition, a box-shaped casing 5
A slider 55 extending in the direction of relative movement (the left-right direction in FIGS. 8A and 8B) is fixed to the floor of the vehicle 1 by a plurality of bolts 54. A groove is provided in the center of the slider 55 in the direction of relative movement, and a bearing 56 is fitted and fixed in the groove.

An adhesive layer 59 is provided on the bottom of the relative motion member 21.
The track rail 60 is adhered through. The track rail 60 fits in the above-mentioned groove with a gap. Thus, the relative motion member 21 is movable with respect to the slider 55 via the bearing 56.

The relative movement member 21 and the track rail 60 are disposed so as to penetrate the casing 51 in the direction of relative movement. Further, both ends of the relative motion member 21 and the track rail 60 are supported by the bolts 58 on the support base 5.
7 and fixed. The vibrator 11 is mounted on the upper surface of the relative motion member 21 while being pressed by the pressing unit 32. The drive device 50 of the present embodiment is configured as described above.

In the driving device 50, by driving the ultrasonic actuator 10, the pressing unit 31, the vibrator 11, and the slider 55 are fixedly held by the relative movement member 21 and the track rail 60 which are fixed and installed. The casing 51 reciprocates linearly in the left-right direction.

FIG. 10 shows a case where the start position, the pressing force change position, the inversion position, and the stop position of the vibrator 11 with respect to the relative movement member 21 are all set in advance in the driving device 50 shown in FIGS. FIG. 4 is a flowchart illustrating a control example of a pressing force control device 48; FIG.
11 is a graph showing a pressing force P that changes according to the position of the vibrator 11 under the control shown in FIG.

As shown by the graph in FIG. 11, the start position and the stop position are x ₀ , the first pressure change position is x ₁ , the second pressure change position is x _2, and
An inverted position and x _3. Further, the first pressing force at the start and stop positions x ₀ and P _1, the first and pressure change position x ₁ and the second pressure between the second pressure changing position x ₂ P ₂ (however, P ₂ > P ₁ ).

In step (hereinafter simply referred to as “S”) 1 in FIG. 10, the drive control circuit 20
Does not output a driving instruction signal to drive the vibrator 11 to the pressing force control device 48. At this time, the vibrator 11 moves the start position x _{0 with} respect to the relative motion member 21.
Stopped at.

In S2, the pressing force control device 48 determines whether or not a drive instruction signal has been output from the drive control circuit 20. When detecting that the drive instruction signal has been output, the process proceeds to S3.

In S 3, the controller 46 of the pressurizing force control device 48 determines, via the D / A converter 43, the amount of pneumatic pressure that gives the first pressurizing force P ₁ to the electropneumatic regulator 40 of the gas supply system 38. Instruct to output. This allows
Pressure against the vibrator 11 is a P _1.

In S4, the pressing force control device 48 determines whether or not a drive start signal indicating that a drive signal has been supplied from the drive control circuit 20 to the vibrator 11 has been output. When it is detected that the drive start signal has been output, S
Go to 5. At this time, the vibrator 11 applies the first pressing force P ₁
Then, the driving is started in a state where the relative motion member 21 is pressed.

In S5, the pressing force control device 48 starts inputting the position information of the vibrator 11 from the position detecting means 49. The position detecting means 49 continuously detects the position information of the vibrator 11 with respect to the relative motion member 21 and outputs the position information to the pressing force control device 48.

In S6, the pressure control device 48 determines whether or not the vibrator 11 has reached the _first pressure change position x1, based on the position information output from the position detecting means 49. Then, the vibrator 11 is moved to the first pressure changing position x
If it reaches ₁ , the process proceeds to S7.

In S 7, the controller 46 of the pressurizing force controller 48 determines, via the D / A converter 43, the amount of pneumatic pressure that gives the second pressurizing force P ₂ to the electropneumatic regulator 40 of the gas supply system 38. Instruct to output. This allows
Pressure against the vibrator 11 is changed to P _2, the vibrator 1
1 is driven in a state in which the second pressure P ₂ has been pressurized to the relative moving member 21.

[0079] In S8, pressure controller 48, based on the position information output from the position detecting means 49, determines whether the vibrator 11 has reached the second pressure changing position x _2. Then, the vibrator 11 is moved to the second pressure changing position x
If it reaches ₂ , the process proceeds to S8.

In S 9, the controller 46 of the pressurizing force control device 48 determines, via the D / A converter 43, the amount of air pressure that gives the first pressurizing force P ₁ to the electropneumatic regulator 40 of the gas supply system 38. Instruct to output. This allows
Vibrator 11 is driven in a state where the pressure is changed to P _1, reaches the reversal position x _3. A reversal instruction signal is output from the drive control circuit 20 to the vibrator 11, whereby
The vibrator 11 is inverted and driven while being pressed by the _first pressure P1.

In S10, the pressing force control device 48
Based on the position information output from the position detection unit 49, the vibrator 11, it is determined whether reaches the second pressure changing position x ₂ again after inversion. Then, when the vibrator 11 has reached the second pressure changing position x _2, the process proceeds to S11.

In S 11, the controller 46 of the pressure control device 48 sends the second pressure P ₂ to the electropneumatic regulator 40 of the gas supply system 38 via the D / A converter 43.
To output the amount of air pressure that gives Thus, pressure against the vibrator 11 is changed to P _2, the vibrator 11 is driven in a state in which the second pressure P ₂ has been pressurized to the relative moving member 21.

In S12, the pressing force control device 48
Based on the position information output from the position detecting means 49, it is determined whether or not the vibrator 11 has reached the _first pressure change position x1. When the vibrator 11 has reached the _first pressure changing position x1, the process proceeds to S13.

In S 13, the controller 46 of the pressurizing force controller 48 sends the first pressurizing force P ₁ to the electropneumatic regulator 40 of the gas supply system 38 via the D / A converter 43.
To output the amount of air pressure that gives Thus, pressure against the vibrator 11 is changed to P _1, the vibrator 11 is driven in a state where the first pressure P ₁ has been pressurized to the relative moving member 21.

In S14, the pressing force control device 48
It is determined whether or not a stop instruction signal to stop driving the vibrator 11 has been output from the drive control circuit 20. If the stop instruction signal has been output, the process proceeds to S15, and if not, the process proceeds to S6 to perform an inversion operation.

In S15, the pressing force control device 48
Based on the position information output from the position detecting means 49, it determines whether the vibrator 11 has reached the stop (start) position x _0. Then, when the vibrator 11 has reached the stop position x _0, the process proceeds to S16.

[0087] In S16, pressure controller 48 stops the control, vibrator 11 is stopped at the stop position x ₀ to the relative movement member 21. At this time, the vibrator 11
It is in a state where the relative motion member 21 is pressed by the first pressing force P ₁ .

The distance between the first pressing force change position x ₁ and the stop position (start position) x _{0 at} which the vibrator 11 stops or reverses is determined by the vibrator 11 changing the first pressing force change position. between the passes through the position x ₁ until it reaches the stop position x _0, by the air supply system 38 and the pressure mechanism 31, the pressure in the first pressure P ₁ from the second pressure P ₂ Set the distance so that it can be changed. Similarly, the distance between the second pressure changing position x ₂ and the inverted position x ₃ is between the vibrator 11 passes through the second pressure changing position x ₂ until it reaches the inverted position x ₃ in, the air supply system 38 and the pressure mechanism 31, is set to a distance such that pressure is changed from the second pressure P ₂ to the first pressure P _1.

With this control, the pressurizing mechanism 31 applies the first pressing force P generated near the time when the relative movement direction is changed.
₁ and has a second and pressure P ₂ is generated in other than the vicinity of the time of relative movement direction change, the first pressure P ₁ and the second
Less than pressure P ₂ of, and, the first pressure P ₁ exerts varying pressure variation function so as to minimize the time of relative movement direction change.

Therefore, the vibrator 11 and the relative motion member 21
The stop position x ₀ where the wear of the driving force output portions 12a and 12b is likely to occur due to the increase in the sliding resistance between
And pressure at the reversing position x _3, both can be reduced.

As a result, the amount of abrasion powder generated due to an increase in the driving time is remarkably suppressed, and the vibrator 11 fixes the vibrator 11 and the relative motion member 21 and moves the stop position x ₀ and the inversion position x ₃ respectively. Generation of abnormal noise when passing through is both prevented, and stable driving can be performed for a long period of time.

In particular, since the abrasion powder is often found to be deposited at a high density with a certain width in the driving direction at the reversal position, the effect of the present invention is remarkable. FIG. 12 is a flowchart illustrating another control example of the pressing force control device 48 in the driving device 50 illustrated in FIGS. 8 and 9. Steps S1 to S6 are the same as steps S1 to S6 in FIG.

In S6, the pressing force control device 48 measures the elapsed time from the start of driving by the timer mechanism set in the controller 46, and determines whether or not the measured value t has been reached. The set value t is determined based on the time required for the vibrator 11 to start driving and reach a position separated from the stopped position by a predetermined distance.
In this case, the predetermined distance is set to be longer than at least the length of the vibrator 11 in the driving direction. When the elapsed time from the start of driving reaches the set value t, the pressing force control device 48 proceeds to S7.

In S 7, the controller 46 of the pressurizing force control device 48 determines, via the D / A converter 43, the amount of pneumatic pressure that gives the second pressurizing force P ₂ to the electropneumatic regulator 40 of the gas supply system 38. Instruct to output. This allows
Pressure against the vibrator 11 is changed to P _2, the vibrator 1
1 is driven in a state in which the second pressure P ₂ has been pressurized to the relative moving member 21.

In S8, the pressing force control device 48 determines whether or not a stop instruction signal for stopping the driving of the vibrator 11 has been input from the drive control circuit 20. If the stop instruction signal has not been output, the process proceeds to S9, and if it has been output, the process proceeds to S14.

In S9, the pressing force control device 48 determines whether or not the drive control circuit 20 has output a reversal instruction signal for reversing the drive direction of the vibrator 11. If the inversion instruction signal has been output, the process proceeds to S10. When the inversion instruction signal is not output, the pressing force control device 48
Maintains the _second pressure P ₂ , and the vibrator 11 is driven while being pressed against the relative motion member 21 by the _second pressure P ₂ .

In S 10, the controller 46 of the pressurizing force control device 48 sends the first pressurizing force P ₁ to the electropneumatic regulator 40 of the gas supply system 38 via the D / A converter 43.
To output the amount of air pressure that gives Thus, pressure against the vibrator 11 is changed to P _1, the vibrator 11 is driven in a state where the first pressure P ₁ has been pressurized to the relative moving member 21.

In S11, the pressing force control device 48
Based on the information from the position detection means 49, it is determined whether or not the vibrator 11 has been inverted. If the vibrator 11 has been inverted, the process proceeds to S12.

In S 12, the controller 46 of the pressurizing force controller 48 sends the second pressurizing force P ₂ to the electropneumatic regulator 40 of the gas supply system 38 via the D / A converter 43.
To output the amount of air pressure that gives Thus, pressure against the vibrator 11 is changed to P _2, the vibrator 11 is driven in a state in which the second pressure P ₂ has been pressurized to the relative moving member 21.

In S13, the pressing force control device 48
It is determined whether or not a stop instruction signal to stop driving the vibrator 11 has been output from the drive control circuit 20. If the stop instruction signal has been output, the process proceeds to S14, and if not, the process proceeds to S9.

In S14, the controller 46 of the pressure control device 48 sends the first pressure P ₁ to the electropneumatic regulator 40 of the gas supply system 38 via the D / A converter 43.
To output the amount of air pressure that gives Thus, pressure against the vibrator 11 is changed to P _1. Vibrator 11 is driven in a state where the first pressurized to relative moving member 21 under a pressure P ₁ while decelerating.

In S15, the pressing force control device 48 stops the control, and the vibrator 11 is stopped. At this time, the vibrator 11 is in the pressurized state in the relative moving member 21 in the first pressure P _1.

As described above, in the control example shown in FIG. 12, as compared with the control example shown in FIG. 10, any of the start position, the stop position, the first pressure change position, and the second pressure change position are changed. The pressure is adjusted based on any one of the drive instruction signal, the inversion instruction signal, and the stop instruction signal output from the drive control circuit 20 without setting. That is, the time from when each of the instruction signals is output to when the vibrator 11 actually performs the instructed operation is considered in advance, and the driving force is changed during this time.

FIGS. 13 to 17 are graphs showing the applied pressure P that changes depending on the position of the vibrator 11 in examples other than the example shown in FIG. In the example shown in the graph of FIG. 13, the first pressing force P _{1 is set} to zero, so that it is possible to more reliably prevent the vibrator 11 and the relative motion member 21 from sticking to each other than the case shown in the graph of FIG. 12. it can.

In the example shown in the graph of FIG. 14, the pressing force is changed so as to become a part of the upwardly convex graph. Therefore, when the pressure is increased, the pressure can be quickly increased to a value close to the target pressure in a short time. Further, the wear powder generated due to the change in the pressing force is transferred to the pressing force changing position x ₁ ,
x ₂ can be generated in a dispersed manner, and the vibrator 1
1 and the relative movement member 21 can be more reliably prevented from sticking.

In the example shown in the graph of FIG. 15, the pressing force is changed so as to become a part of the downwardly convex graph. Therefore, when the pressure is reduced, the pressure can be reduced to a value close to the target pressure in a short time. Further, the wear powder generated due to the change in the pressing force is transferred to the pressing force changing position x ₁ ,
x ₂ can be generated in a dispersed manner, and the vibrator 1
1 and the relative movement member 21 can be more reliably prevented from sticking.

In the example shown in the graph of FIG. 16, the pressing force is rapidly and discontinuously changed at the pressing force changing positions x ₁ and x ₂ .
This makes it possible to make the pressurizing force change patterns the same at the time of pressurizing and at the time of depressurizing, and to significantly reduce the range required for changing the pressurizing force. Therefore, the abrasion powder generated due to the change in the pressing force can be concentrated in a narrow range near the pressing force changing positions x ₁ and x ₂ . Therefore, the stop position x ₀ and the inversion position x ₃
It is possible to reduce the amount of accumulated wear powder in each case, and it is possible to more reliably prevent the vibrator 11 and the relative motion member 21 from sticking.

Further, in the example shown in the graph of FIG. 17, between the stop position x ₀ and the first pressure change position x _1, and between the second pressure change position x ₂ and the reversal position x _3. , A third pressure P ₃ (where P ₁ <P ₃ <P ₂ ). Thereby, the amount of change in the pressing force is suppressed as compared with the example shown in the graph of FIG. 16, and the sticking between the vibrator 11 and the relative motion member 21 can be more reliably prevented.

With the ultrasonic actuator 10 according to the present embodiment, the amount of abrasion powder generated due to the increase in the driving time can be remarkably suppressed. Therefore, the vibrator 1
1 can be prevented from sticking to the relative motion member 21 and the generation of abnormal noise can be prevented, and stable driving can be performed for a long period of time.

Note that, for example, even when the main power supply is turned off, the ultrasonic actuator 10 of the present embodiment can be used.
Then, the self-holding property which is an attribute of the ultrasonic actuator 10 can be maintained by continuously supplying the air to the cylinder 34. In this case, even if the air supply is continued, the generation of abrasion powder is extremely suppressed in the present embodiment, so that the fixation at the time of restarting does not occur. If it is difficult to supply air to the cylinder 34 when the main power supply is turned off, the self-holding property may be secured by another appropriate means.

[Modification] In the embodiment, the case where the vibration actuator is an ultrasonic actuator is taken as an example, but the vibration actuator according to the present invention is not limited to such a form. The present invention is similarly applied to a vibration actuator using a vibration region other than the ultrasonic wave.

Further, in the description of the embodiment, the case where the sliding resistance increases when the relative movement direction changes is taken as an example, but the vibration actuator according to the present invention is not limited to such an embodiment. . For example, when the relative movement speed between the vibrator and the relative movement member is changed, the sliding resistance increases, so the present invention is applied.

Further, in the description of the embodiment, the case where the vibrator runs with respect to the fixed relative motion member is taken as an example, but the vibration actuator according to the present invention is not limited to such a form. For example, with the vibrator fixed,
The case where the relative motion member travels with respect to the vibrator is also included in the present invention.

Further, in the description of the embodiment, the vibrator utilizing the first-order longitudinal vibration and the fourth-order bending vibration is taken as an example.
The vibration actuator according to the present invention is not limited to such a form. For example, the present invention is similarly applied to a vibrator utilizing primary longitudinal vibration and secondary, sixth, or eighth-order bending vibration.

Further, in the description of the embodiment, the case where the sliding member is adhered to the groove of the elastic body to form the protruding driving force extracting portion has been described as an example. However, the vibration actuator according to the present invention has such a structure. It is not limited to a specific form. For example, a projection may be formed integrally with the elastic body, and a sliding material may be bonded to the tip of the projection.

Further, the pressing mechanism used in the description of the embodiment is merely an example, and the vibration actuator according to the present invention is not limited to this pressing mechanism. The present invention is equally applicable to any pressurizing mechanism having a pressurizing force variable function for adjusting the pressurizing force when the sliding resistance generated in the driving force take-out section increases.

Furthermore, in the embodiment, the piezoelectric body is used as the electromechanical transducer. However, the vibration actuator according to the present invention is not limited to this form, and is capable of performing mutual conversion between electric energy and mechanical energy. If,
Applies equally. Other than the piezoelectric body, for example, an electrostrictive element or a magnetostrictive element is exemplified.

[0118]

As described in detail above, claims 1 to 5
According to the fifth aspect of the present invention, it is possible to remarkably reduce the amount of abrasion powder generated as the driving time of the vibration actuator increases. Therefore, the sticking of the vibrator and the relative motion member and the generation of abnormal noise are prevented, and stable driving can be performed for a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an ultrasonic actuator according to an embodiment.

FIG. 2 is a perspective view showing the ultrasonic actuator of the embodiment in a partially transparent state.

FIG. 3 is an explanatory diagram showing longitudinal vibration and bending vibration generated in a vibrator.

FIG. 4 is a block diagram showing a drive control circuit of the vibrator.

FIG. 5 is an explanatory diagram showing a state over time in which a primary longitudinal vibration and a fourth-order bending vibration are combined to generate an elliptical motion in a driving force extraction unit.

FIG. 6 is an explanatory diagram showing the configuration of each of an air supply system and a pressure control device.

FIG. 7 is an explanatory diagram showing connection between the drive control circuit shown in FIG. 4 and the air supply system and the pressure control device shown in FIG. 6;

FIG. 8A is a top view of a driving device incorporating the ultrasonic actuator according to the embodiment, and FIG. 8B is a side view.

FIG. 9 is a cross-sectional view taken along the line EE in FIG. 8 (A) or FIG. 8 (B).

10 is a flowchart showing a control example in a case where the start position, the pressing force change position, the inversion position, and the stop position of the vibrator with respect to the relative motion member are all set in advance in the driving device shown in FIGS. 8 and 9; It is.

11 is a graph showing a pressing force P that changes depending on the position of a vibrator under the control shown in FIG.

FIG. 12 is a flowchart showing another control example of the driving device shown in FIGS. 8 and 9;

FIG. 13 is a graph showing a pressing force that changes depending on the position of a vibrator in an example other than the example shown in FIG. 11;

FIG. 14 is a graph showing a pressing force that changes according to the position of a vibrator in an example other than the example shown in FIG. 11;

FIG. 15 is a graph showing a pressing force that changes depending on the position of a vibrator in an example other than the example shown in FIG. 11;

FIG. 16 is a graph showing a pressing force that changes according to the position of a vibrator in an example other than the example shown in FIG. 11;

FIG. 17 is a graph showing a pressing force that changes according to the position of a vibrator in an example other than the example shown in FIG. 11;

FIG. 18 is a perspective view showing a known vibration actuator.

19 is an explanatory diagram showing an example of two vibration waveforms generated in a vibrator constituting the vibration actuator of FIG.

FIG. 20 is a graph showing an example of a pressing force between a vibrator and a relative motion member with respect to a position of the vibrator with respect to the relative motion member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vibration actuator 11 Vibrator 12a, 12b Driving force take-out part 21 Relative motion member 31 Pressurization mechanism 32 Pressurization part 33 Piston 34 Cylinder 35 First chamber 36 Second chamber 35a, 35b Air port 38 Air supply system 48 Pressure control apparatus

Claims (5)

[Claims] 1. A vibrator, a relative motion member that generates a relative motion between the vibrator, and a pressing force generated between the vibrator and the relative motion member to provide a vibrator. A pressure mechanism that presses the vibrator and the relative motion member through a driving force extraction unit. The pressure mechanism includes a sliding mechanism that increases a sliding resistance generated in the driving force extraction unit. A vibration actuator having a pressing force variable function for adjusting the pressing force when resistance increases. 2. The vibration actuator according to claim 1, wherein the increase in the sliding resistance is a change in a direction or a speed of the relative motion. 3. The vibration actuator according to claim 2, wherein the pressing force is other than a first pressing force generated near a time when the direction of the relative motion is changed and a pressure other than near a first time when the direction of the relative motion is changed. And a second pressing force generated larger than the first pressing force. 4. The vibration actuator according to claim 3, wherein the first pressing force changes so as to be minimum when the direction of the relative motion is changed. 5. The method according to claim 1, wherein:
In the vibration actuator described in the paragraph, the pressurizing mechanism, a pressurizing unit that presses the vibrator or the relative motion member, a piston connected to the pressurizing unit,
A cylinder accommodating the piston, a gas supply system for changing a pressure acting on the piston by supplying gas to the cylinder or discharging gas from the cylinder, and based on information on the relative motion. A control device for controlling the gas supply system.