JP2004187384A - Vibration actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration actuator which is usable under a clean environment, has a long life, and can stably operate over a long time. <P>SOLUTION: The vibration actuator generates ultrasonic vibration at a vibrator by driving an ultrasonic motor, and relatively moves a movable body by a frictional member by the ultrasonic vibration. Further, the actuator is provided with a dust removal member for removing dust such as abrasion powder adhering to the surface of the movable body by abutting against the surface of the movable body and sliding. The dust removable member is formed of a porous substance having continuous pores. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator that moves a movable body via a friction member using ultrasonic vibration, and particularly to a device that removes dust such as abrasion powder generated by sliding of the movable body and the friction member.
[0002]
[Prior art]
Conventionally, as a dust removing means of this type of vibration actuator, for example, Japanese Patent Application Laid-Open No. 11-18446 has been disclosed. According to this publication, in a vibration actuator in which an ultrasonic wave generates an elliptical vibration in a vibrator and the relative motion member relatively moves by the elliptical vibration, dust generated on a contact surface between the vibrator and the relative motion member is removed. An arrangement for doing so is disclosed.
[0003]
That is, as shown in FIG. 7, the vibration actuator 51 includes a vibrator 52 having a piezoelectric element (not shown) and a relative motion member 53, and makes the vibrator 52 and the relative motion member 53 contact each other. Thus, by applying an AC voltage to the piezoelectric element, an elliptical motion is generated in the vibrator 52, and the relative motion member 53 is relatively moved.
[0004]
At that time, since the relative motion member 53 slides in contact with the vibrator 52, the surface of the relative motion member 53 is worn due to friction and has a short life. Therefore, dust removing means 54 is provided near both ends of the relative motion member 53 to remove dust such as abrasion powder and dust generated by sliding between the vibrator 52 and the relative motion member 53.
[0005]
As a means for removing dust, a brush 55 (FIG. 8A), a peeling claw 56 (FIG. 8B), a felt 57 (FIG. 8C), and a roller 58 (FIG. 8D). ) Is known that removes dust from the surface of the relative movement member 53 with the movement of the relative movement member 53. That is, as shown in FIG. 8A, the brush 55 is fixed by a mounting pin 60 or the like protruding from the base member 59 of the actuator, and sweeps out dust from the surface of the relative movement member 53. As shown in FIG. 8B, dust is peeled off from the surface of the relative motion member 53 by a sharp tip 61 made of resin or the like.
[0006]
The felt 57 is held by the base 62 as shown in FIG. 8C, and the surface of the relative movement member 53 is wiped. Further, as shown in FIG. The surface is wiped off by wrapping an application paper such as a silk paper or a cloth and bringing it into pressure contact with the relative movement member 53. In this case, dust adhered to the relative movement member 53 can be removed by applying a cleaning agent to the roller 58. Further, by bringing another roller 63 for cleaning into contact with the roller 58, Dust adhered to the roller 58 can also be removed.
[0007]
In addition, 64 is a pressing mechanism for adjusting the pressing force of the vibrator 52 to the relative motion member 53, and 65 is a feed roller for sandwiching and holding the relative motion member 53 together with the vibrator 52. .
[0008]
[Problems to be solved by the invention]
However, when the brush 55 is used as the dust removing means, there is a problem that the brush 55 has no strength and is easily damaged. Further, when the peeling claw 56 is used, there is a problem that the peeling claw 56 is damaged or noise is easily generated by sliding. When the brush 55 or the peeling claw 56 is used, dust such as abrasion powder or dust removed from the surface of the relative motion member 53 is separated from the brush 55 or the peeling claw 56, and contaminates the periphery. There was a problem.
[0009]
In addition, paper or cloth wound around the felt 57, the roller 58, or the like as dust removing means is clogged by dust such as abrasion powder and dust, and the dust removing performance decreases with use. There was a problem. As a result, dust remains on the surface of the relative motion member 53, and the dust causes wear on the surface of the relative motion member 53, thereby shortening the life of the apparatus and causing the operation to become unstable due to the adhesion of dust. was there.
[0010]
An object of the present invention is to provide a vibration actuator which can be used even in a clean environment, has a long life, and operates stably for a long period of time in view of the above points.
[0011]
[Means for Solving the Problems]
An object of the present invention is to provide a vibration actuator that generates ultrasonic vibrations on a vibrating body by a piezoelectric element and relatively moves a movable body via a friction member by the ultrasonic vibrations. A dust removing member that slides and removes dust such as abrasion powder attached to the surface of the movable body, and the dust removing member is formed of a porous material having continuous pores. Is done.
[0012]
The above object is effectively achieved by making the porous substance made of a synthetic resin. Further, the above object is effectively achieved by setting the porosity of the porous substance to be 70% or more and 98% or less.
[0013]
The above object is effectively achieved by making at least one of the surfaces of the friction member and the movable body made of ceramic.
[0014]
Further, the above object is achieved more effectively when the porous substance has a spongy tissue.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows a vibration actuator A according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an ultrasonic motor, and the ultrasonic motor 1 has a piezoelectric element 3 having an electrode 2 attached thereto and a piezoelectric element 3 on the piezoelectric element 3. And the friction member 4 provided on the second member. Thus, by applying a high-frequency voltage to the electrode 2 to expand and contract the piezoelectric element 3, the piezoelectric element 3 is vibrated, and thereby a driving force is obtained by using the elliptical motion generated in the friction member 4. .
[0017]
Here, for example, barium titanate, lead zirconate titanate, or the like is used for the piezoelectric element 3, and a metal material such as aluminum, iron, stainless steel, or a material such as alumina, silicon carbide, or zirconia is used for the friction member 4. Ceramic materials are used.
[0018]
The ultrasonic motor 1 is mounted at a predetermined position by a motor mounting frame 5, and the piezoelectric element 3 is supported by an elastic support 7 in a case 6 so that predetermined driving characteristics are not impaired. A preload adjusting screw 9 screwed into the screw hole 8 is attached to the bottom surface of the motor mounting frame 5, and a pressing mechanism P that adjusts a pressing force to the movable body 10 by tightening the preload adjusting screw 9. Is configured.
[0019]
With these configurations, by applying a voltage to the piezoelectric element 3 from an AC power supply, the piezoelectric element 3 generates ultrasonic vibration of 20 kHz or more. When an elliptical motion is generated in the friction member 4 by this ultrasonic vibration, the movable body 10 pressed against the friction member 4 generates a linear reciprocating motion in the direction of the arrow in FIG. That is, as shown in FIG. 2, when, for example, an elliptical motion occurs in the friction member 4 in the counterclockwise direction (the direction of the arrow in FIG. 2B), the movable body 10 is moved by the elliptical motion at a point A1 on the surface of the friction member 4. The movable body 10 comes in contact with and is dragged by the movable body 10 so as to linearly move on the surface of the friction member 4 in the direction of the arrow in FIG. 2C.
[0020]
Dust removing means 11 is provided on both sides of the friction member 4 so as to remove dust such as abrasion powder and dust generated by sliding between the movable body 10 and the friction member 4. . The dust removing means 11 includes a cylindrical roller member 12, a plate-like support member 13 for supporting the roller member 12, and an actuator 14 for reciprocating the support member 13 in the vertical direction in FIG. By driving the actuator 14, the roller member 12 is brought into contact with the movable body 10 to remove dust adhering to the surface of the movable body 10 on the contact side with the friction member 4.
[0021]
For the roller member 12 of the dust removing means, a porous material having continuous pores such as sponge is used, and preferably, a synthetic resin such as polyurethane, polyethylene, or polyvinyl alcohol is used. In the case of this synthetic resin, the pores 15 existing inside the porous substance are continuous, and the separation of dust from the porous material itself can be prevented. That is, as shown in FIG. 3, continuous pores 15, 15,... Are formed innumerably inside the porous material, and the dust a1 removed by sliding with the movable body 10 is It is captured in the pores 15. The dust a <b> 1 is further pushed from the opening of the air hole 15 in the order of a <b> 2, a <b> 3, a <b> 4, and is held inside the air hole 15.
[0022]
The porosity (porosity) of the porous substance used as the dust removing means is preferably 70% or more and 98% or less. This is because, as shown in FIG. 4, when the porosity is less than 70%, the number of pores 15 is small and dust is collected in the pores 15 with respect to the dust collecting ability in the range of porosity 70% to 98%. This is because the dust collecting ability is reduced. On the other hand, if it exceeds 98%, the strength of the porous substance is lost, so that a phenomenon such as so-called settling occurs, and practical strength cannot be maintained.
[0023]
Further, by using a substance having a spongy structure, generally called a sponge, as the porous substance, the effect of retaining dust once captured as it is can be enhanced.
[0024]
When the piezoelectric actuator is driven in the atmosphere at a standard applied pressure load of 100 mm / s, abrasion powder of about 1 to 5 μm is generated from the ceramic friction member and the movable body. At this time, the pore diameter of the porous substance containing the substance having a spongy tissue is preferably 50 to 200 μm in average diameter, and about 0.1 to 3 μm in minimum diameter.
[0025]
In the above embodiment, the cylindrical roller member 12 is used as the dust removing means. However, the dust removing means may be flat, and the dust removing means and the movable body 10 are brought into planar contact with each other, so that the dust removing means adheres to the surface of the movable body 10. You may make it remove the dust which was made. Further, the porous substance may be used not only in a dry state but also by impregnating a liquid such as a solvent.
[0026]
Here, as shown in FIGS. 5 and 6, the dust removing unit 11 operates in two states: when the roller member 12 is not in contact with the movable body 10, and when the roller member 12 is in contact with the movable body 10. Can be switched.
[0027]
That is, when removing dust adhering to the movable body 10, the actuator 14 is driven to move the roller member 12 from the position shown in FIG. 5 to the position shown in FIG. The contact causes the roller member 12 and the movable body 10 to slide. Due to the sliding with the roller member 12, the abrasion powder and dust attached to the movable body 10 are removed from the surface on the contact surface side with the friction member 4.
[0028]
On the other hand, when the actuator 14 is driven in the opposite direction (downward in FIG. 6) to the above-described case of removing dust, the roller member 12 can be completely separated from the movable body 10 as shown in FIG. Thereby, the maintainability at the time of replacement of the roller member 12 is improved, and unnecessary external force is prevented from being applied to the roller member 12 even when dust removal is not necessary, and the life of the roller member 12 can be extended. Such an effect can be obtained.
[0029]
The setting of the opportunity (timing) and duration for removing the dust by bringing the roller member 12 into contact with the movable body 10 depends on the operation time of the movable body 10 or the contact of the movable body 10 with the friction member 4. It may be automatically performed by optically monitoring the dust status of the contact surface and detecting the change in the reflectance or the like, or of course, manually by an operator's arbitrary judgment. .
[0030]
Further, for the above-described reason, according to the present invention, the dust removing means 11, specifically, the roller member 12 is switched between contacting and non-contacting with the movable body 10 to create two states of operation and non-operation. However, it is needless to say that the object of dust removal, which is the essence of the present invention, can be achieved even when the roller member 12 is always used in contact with the movable body 10.
[0031]
Since the roller member 12 as the dust removing means is formed of a porous material having continuous pores 15, 15,..., The dust scraped off by sliding with the roller member 12 is removed from the pores 15. Since it is trapped inside and pushed into the back of the pores 15, the trapping ability is higher than that of cloth or felt, and clogging is unlikely to occur. Further, the dust that has become fine in the pores 15 is held deep inside the pores 15 and does not separate from the porous substance. Therefore, unlike the case where a brush or a peeling claw is used as dust removing means, the captured dust does not scatter around. As a result, when a porous substance is used as the dust removing means, it can be used even in a clean working environment, has a long life, and can operate stably over a long period of time.
[0032]
The structure of the ultrasonic motor is not limited to the present embodiment, but may be another type of motor.
[0033]
【The invention's effect】
As described above, according to the vibration actuator of the present invention, the ultrasonic vibration is transmitted from the elastic vibrator to the friction member by the ultrasonic motor, and the movable member is moved by the friction drive by the friction member. At this time, dust such as abrasion powder and dust attached to the contact surface with the movable body is removed by the dust removing means. Since the dust removing means is made of a porous material having an infinite number of continuous pores, dust such as abrasion powder adhered to the friction member is swollen by the movable body to form pores of the porous material. Is trapped inside and pushed deeper into the pores. As a result, according to this vibration actuator, the supplemented dust does not scatter around and can be used even in a clean environment, has a long life, and operates stably for a long time. Brief description of]
FIG. 1 is a partial cross-sectional view schematically illustrating a structure for moving a movable body by a vibration actuator according to the present invention.
FIG. 2 is a diagram illustrating the operation principle of an ultrasonic motor.
FIG. 3 is a diagram showing a distribution state of pores formed in a porous material as dust removing means.
FIG. 4 is a diagram showing the relationship between the porosity of a porous substance and the trapping rate.
FIG. 5 is an explanatory diagram showing a state in which the dust removing unit does not contact the movable body and is not operated.
FIG. 6 is an explanatory diagram showing a state at the time of an operation of removing dust adhering to the surface of the movable body by contacting the dust removing means with the movable body.
FIG. 7 is a diagram showing a schematic structure of a dust removing means provided in a conventional vibration actuator.
8A and 8B show a conventional dust removing means, wherein FIG. 8A shows a brush, FIG. 8B shows a peeling claw, FIG. 8C shows a felt, and FIG. 8D shows a schematic structure of a paper or cloth wound around a roller. FIG.
[Explanation of symbols]
A Vibration actuator 1 Ultrasonic motor 2 Electrode 3 Piezoelectric element 4 Friction member 10 Movable body 15 Pores

Claims (5)

A vibration actuator that generates ultrasonic vibration on a vibrating body by a piezoelectric element, and relatively moves a movable body via a friction member by the ultrasonic vibration,
A dust removing member that comes into contact with the surface of the movable body and removes dust such as abrasion powder attached to the surface of the movable body by sliding; the dust removing member is formed of a porous material having continuous pores; A vibration actuator. The vibration actuator according to claim 1, wherein the porous material is made of a synthetic resin. 3. The vibration actuator according to claim 1, wherein the porosity of the porous material is 70% or more and 98% or less. The vibration actuator according to claim 1, wherein at least one surface of the friction member or the movable body is made of ceramic. The vibration actuator according to claim 1, wherein the porous material has a spongy tissue.

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