JP2013021777A - Vibration type actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration type actuator which can efficiently release heat generated as sliding loss energy on a contact portion interface and can alleviate or suppress rise in the interface temperature.SOLUTION: In a vibration type actuator, by application of an alternating signal to an electromechanical energy conversion element, vibrational waves excited by a vibrating body cause friction drive of a moving body, and the moving body is relatively displaced to the vibrating body. Either one of the vibrating body or the moving body has a contact spring structure including a frictional contact portion coming into frictional contact with the other, and a clearance is formed between the contact spring structure and a body portion constituting the vibrating body or the moving body. Heat release means which releases heat generated in the frictional contact portion is interposed in the clearance.

Description

  The present invention relates to a vibration type actuator that generates vibration in a vibrating body and applies a driving force using the vibration energy.

Generally, a vibration type actuator (vibration wave motor such as an ultrasonic motor) has a vibrating body in which driving vibration is formed and a moving body that is in pressure contact with the vibrating body. It is comprised so that it may move relatively with drive vibration.
FIG. 9 is a cross-sectional view of a so-called annular ultrasonic motor.
In FIG. 9, 101 is a ring-shaped vibrating body, 102 is a piezoelectric element fixed on one surface of the vibrating body 101, 103 is a friction member installed on the other surface of the vibrating body, and 107 is the vibrating body 101. It is the moving body arrange | positioned at the said friction member 3 side.
Reference numeral 113 denotes a cylindrical contact spring structure, one of which is supported by the moving body 107, the other is processed into a conical shape, and press-contacts the friction member 103 at the tip.
The moving body 107 is pressurized by a pressure spring 109, and the rotational torque of the moving body 107 is transmitted to the shaft 111 via the pressure spring 109 and the disk 113. FIG. 10 is a perspective view of the vibrating body 101 viewed from the moving body 107 side.
In FIG. 10, the vibrating body 101 has a plurality of comb-shaped protrusions 101 a arranged in an annular shape on the surface facing the moving body 107.
A friction member 103 is disposed on each of the plurality of comb teeth. The piezoelectric element 102 is fixed to the surface opposite to the side where the friction member is disposed.
The piezoelectric element 102 is provided with an electrode pattern (not shown). By applying an alternating signal to the electrode pattern, bending vibration is generated in the vibrating body 101 and the moving body 107 is driven.

FIG. 11 shows the structure of the moving body in the vibration type actuator disclosed in Patent Document 1.
As shown in FIG. 11, the moving body 213 has a beam structure that is supported at both ends, thereby providing elasticity in the pressing direction (perpendicular to the plane A).
Specifically, the moving body 213 includes a moving body beam portion 210, a moving body first protrusion 211 extending from both ends of the beam portion 210, and a moving body extending from the beam portion 210 on the contact surface side with the vibrating body 216. The second protrusion 212 and the like are configured.

Japanese Patent No. 03049931

However, the above-described conventional vibration type actuator has the following problems.
In recent years, there has been a demand for higher torque and higher output of vibration type actuators, and accordingly, the force for pressing the moving body 107 in FIG.
The heat generation at the frictional contact portion is predominantly due to the sliding loss energy depending on the surface pressure of the contact portion and the relative slip, and the increase in the motor pressing force causes a rapid temperature increase at the frictional contact portion.
In the conventional configuration, the heat generated at the contact portion is radiated to the moving body main body side through the heat transfer path indicated by the arrow in FIG.
However, since the movable beam portion 210 surrounded by a circle in FIG. 12 has elasticity in the pressurizing direction, it has a relatively thin cross-sectional structure, so that the thermal resistance in this portion is large. .
Thereby, it is difficult to reduce or prevent the temperature rise of the moving body second protrusion 212.

Such a rapid temperature rise of the frictional contact portion due to the large thermal resistance deforms the parts constituting the contact portion and makes the contact state unstable.
In addition, the influence on the mechanical properties of the friction material, such as the coefficient of friction at the contact portion interface, is increased.
Due to these actions, motor performance including durability and the like greatly change, and it becomes difficult to supply a stable driving source.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a vibration type actuator that can efficiently release the heat generated as the sliding loss energy at the interface of the contact portion and reduce or suppress the temperature rise of the interface temperature. And

The vibration type actuator of the present invention includes a vibrating body having an electro-mechanical energy conversion element, and a moving body in pressure contact with the vibrating body,
A vibration type actuator that frictionally drives the moving body by a vibration wave excited by the vibrating body by applying an alternating signal to the electro-mechanical energy conversion element, and moves the moving body relative to the vibrating body; There,
A contact spring structure having a friction contact portion that frictionally contacts either one of the vibrating body or the moving body,
A gap is formed between the contact spring structure and the main body constituting the vibrating body or the moving body,
A heat radiating means for radiating heat generated in the friction contact portion is interposed in the gap.

  According to the present invention, it is possible to realize a vibration type actuator that can efficiently release the heat generated as the sliding loss energy at the interface of the contact portion and reduce or suppress the temperature rise of the interface temperature.

It is a section perspective view of a vibration type actuator in Example 1 of the present invention. It is sectional drawing of the moving body of the vibration type actuator in Example 1 of this invention. It is sectional drawing explaining the contact state of the vibration type actuator in Example 1 of this invention. It is sectional drawing explaining the characteristic structure of the vibration type actuator in Example 1 of this invention. It is a figure which shows the modification regarding the injection hole of the vibration type actuator in Example 1 of this invention. It is a figure which shows the modification of the vibration type actuator in Example 1 of this invention. It is a figure which shows the structural example of the vibration type actuator in Example 2 of this invention. It is a figure which shows the modification of the vibration type actuator in Example 2 of this invention. It is a figure which shows the structure of the annular | circular type ultrasonic motor which is a vibration type actuator of a prior art example. It is a figure which shows the vibrating body structure of the annular | circular type ultrasonic motor which is a vibration type actuator of a prior art example. It is a figure which shows the moving body structure in the vibration type actuator of a prior art example. It is a figure explaining the heat dissipation path | route of the heat energy which generate | occur | produced in the contact part in the vibration type actuator of a prior art example.

  The mode for carrying out the present invention will be described with reference to the following examples.

[Example 1]
As a first embodiment, a configuration example of a vibration type actuator to which the present invention is applied will be described with reference to FIGS.
The vibration type actuator of the present embodiment includes a vibrating body having an electro-mechanical energy conversion element and a moving body that comes into pressure contact with the vibrating body.
Then, by applying an alternating signal to the electro-mechanical energy conversion element, the moving body is frictionally driven by the vibration excited by the vibrating body, and the moving body is moved relative to the vibrating body.
As its specific configuration, FIG. 1 shows a cross-sectional perspective view of the vibration type actuator of the present embodiment.
Reference numeral 1 denotes a vibrating body, which generates a high-frequency bending vibration, which is a driving vibration, by an alternating signal applied to a piezoelectric element (electro-mechanical energy conversion element) 2.
Reference numeral 7 denotes a moving body, which is pressed in the axial direction by the pressure spring 9 via the spring receiving portion 8 and press-contacts with the contact portion of the vibrating body 1.
At this time, the moving body 7 is driven in the rotational direction by the high-frequency vibration of the vibrating body 1, and the driving force is transmitted to the shaft 11 via the spring receiving portion 8, the pressure spring 9, and the disk 12 that are integrally driven.
In FIG. 1, a circled portion is a contact spring structure 13 provided on the moving body 7.

FIG. 2 is an enlarged cross-sectional view of the contact spring structure 13 of FIG.
The moving body 7 includes a contact spring structure 13 having a friction contact portion 4 that makes frictional contact with a vibrating body and a main body portion 10.
The contact spring structure 13 includes a friction contact portion 4, a cylindrical portion 5, and a flange portion 6 projecting radially from the cylindrical portion. A portion other than the contact spring structure 13 is the main body 10. The vibration type actuator of the present embodiment realizes smooth contact by elastically deforming the flange portion 6 having an axial spring property with respect to the motor pressure applied by the pressurizing spring 9. The cylindrical portion 5 connects the friction contact portion 4 and the flange portion 6.
However, this configuration is an example of a contact spring structure. In the present invention, the contact spring structure includes a friction contact portion having a contact surface for transmitting a frictional force, and an elastic portion for providing a spring property in a direction perpendicular to the contact surface. It further has a connection part to connect.
The main body portion is intended to block the vibration of the contact spring structure without escaping to the outside, and has a function of reducing the vibration amplitude.

FIG. 3 is a sectional view for explaining the contact state of the vibration type actuator. FIG. 3 shows the contact state between the vibrating body 1 and the moving body 7 as a cross section passing through the central axis.
A solid line indicates a push-up motion due to driving vibration of the vibrating body 1 during operation, and a broken line indicates a stop time (vibration amplitude is zero).
In response to this push-up motion, the contact spring structure is elastically deformed while maintaining the contact state of the friction contact portion by the link mechanism of the cylindrical portion 5 and the flange portion 6.
At this time, the main body 10 has an amplitude of a level at which elastic deformation can be almost ignored.
In the present embodiment, the contact spring structure 13 is provided on the moving body side, but the present invention is not limited to such a configuration.
It is possible to adopt a configuration in which either one of the vibrating body or the moving body between the vibrating body and the moving body is provided with a contact spring structure having a friction contact portion that frictionally contacts with the other. Even if a contact spring structure having an equivalent function is arranged on the vibrating body side, smooth contact can be realized.
In addition, the present embodiment relates to an annular ultrasonic motor, but the form of the vibrating body is not limited to this, and it can be applied to a vibration type actuator such as a rotary type or a linear type that does not have a comb tooth portion. Applicable configuration.

FIG. 4 is a cross-sectional view for explaining the characteristic configuration of this embodiment.
The moving body 7 in the present embodiment is configured such that a gap is formed between the contact spring structure and the main body portion constituting the moving body.
Specifically, the moving body 7 has a gap surrounded by the main body 10 and the contact spring structure 13, and holds the liquid 14 as an auxiliary member for cooling, which is a heat radiating means, in the gap.
The liquid 14 does not need to completely fill the gap, but as shown in the figure, it is possible to realize effective heat dissipation by filling an amount that forms a heat transfer path between the friction contact portion and the main body portion. Become.
The moving body of the present embodiment has a configuration in which two parts including a contact spring structure and the remaining part are joined, and is obtained by injecting the liquid 14 from the injection hole 16 after joining.
As the liquid for the cooling auxiliary member, it is possible to use grease having excellent heat dissipation such as silicone grease or silver grease having relatively high thermal conductivity.
In addition, as the liquid for the cooling auxiliary member, the same effect can be obtained by using a semi-solid liquid such as cooling water, various oils, liquid metal, or sol.
When the amount of grease to be held is insufficient, the cooling performance can be maintained by replenishing the grease from the injection hole.
If liquid leakage occurs in actual use, the injection hole may be closed.
On the other hand, when the injection hole is not provided, it is possible to obtain this configuration by performing the joining process of the moving body in a state where the cooling liquid is stored in the recess formed by the contact spring structure.

FIG. 5 shows a configuration of a modified example of the present embodiment regarding the position of the injection hole.
In FIG. 4, when the cooling auxiliary member 14 is volatilized or a slight amount of leakage occurs, the injection hole is provided at a position as far as possible from the contact portion so as not to affect the contact portion.
On the other hand, in this modification, the injection hole 16 is provided in the outer peripheral portion of the movable body 7, but the injection hole 16 is formed on the inner peripheral side or in the axial direction in consideration of the centrifugal force acting on the cooling auxiliary member. There is no problem even if it is provided at the top.

FIG. 6 shows another modification of this embodiment.
The modification of FIG. 6 is an example in which the elastic body 15 is used as a cooling auxiliary member held inside the moving body.
In this modification, rubber having a relatively high thermal conductivity is used. The rubber is disposed in a state of being sandwiched between the main body portion and the contact spring structure, and plays a role of transmitting heat generated at the friction contact portion to the main body portion.
The elastic member that can be used in the configuration in this modification needs to have no significant influence on the deformation of the contact spring structure due to drive vibration, and an elastic member having a value smaller than the spring constant of the contact spring structure is selected. It is preferable to select a contact spring structure having a negligible value for the spring constant.

As the elastic body for the cooling auxiliary member in the present embodiment, there can also be used, for example, a resin having a low elasticity with respect to minute deformation of the drive vibration amplitude level of the vibration type actuator, or a thin wire metal wire that has been crushed. .
Alternatively, for example, copper powder having high thermal conductivity, resin powder having increased thermal conductivity by adding, for example, an aluminum filler, foam material, gel, or resin sheet containing graphite having high thermal conductivity may be used. . The same effect can be obtained also by these.

[Example 2]
As a second embodiment, a configuration example of a vibration type actuator having a different form from the first embodiment will be described with reference to FIGS.
In the first embodiment, as a heat radiating means for radiating heat generated in the frictional contact portion, either the liquid or the elastic member is interposed in the gap, whereas in the present embodiment, it is formed on the main body portion side. In addition, a heat conducting member having a noncontact contact surface with the frictional contact portion is interposed in the gap.
The specific configuration is shown in FIG.
As shown in FIG. 7, the moving body 7 has a gap surrounded by the main body 10 and the contact spring structure 13, and the proximity surface forming member 17 configured integrally with the main body 10 inside the gap. have.
The lower surface of 17 shown in FIG. 7 is the proximity surface, and is disposed in a non-contact manner at a position close to the friction contact portion of the contact spring structure.
Gas is interposed between the proximity surface and the friction contact portion, and the heat of the contact portion is radiated by radiation and heat transfer by the gas.
The reason for non-contact arrangement is to prevent the proximity surface forming member 17 from affecting the contact state of the contact portion.
At this time, it is necessary to arrange the proximity surface at a closer distance in order to efficiently dissipate the heat generated by the frictional contact.
In consideration of realistic machining accuracy commensurate with the cost, it is preferable to approach to about 0.1 mm.

FIG. 8 shows a modification of this embodiment.
In the modification shown in FIG. 8, the liquid or elastic member shown in the first embodiment is filled as a cooling auxiliary member between the proximity surface and the friction contact portion.
With this configuration, a heat transfer path having a low thermal resistance is formed from the heat generation source to the main body, and heat generation from the frictional contact portion can be relieved with high efficiency.

As described above, according to the configuration of the present invention in which the heat dissipation means for radiating the heat generated in the friction contact portion is interposed in the above-described gap, the heat of the friction contact portion is reduced with a large thermal resistance. It is possible to dissipate heat without intervention.
Further, it is possible to alleviate or prevent the temperature rise of the frictional contact portion accompanying the increase in torque and output of the motor, and maintain stable performance.
In addition, it is possible to adopt a shape that is simple and has a small manufacturing load, and it is possible to avoid a significant increase in cost due to the use of a special cooling device.
Furthermore, the existing space can be used effectively and an increase in the space occupied by the vibration actuator can be avoided.
These configurations can be applied to vibration type actuators used in a wide range of fields including copying machines, interchangeable lenses for cameras, and the like, thereby making it possible to cope with high output.

DESCRIPTION OF SYMBOLS 1: Vibrating body 2: Piezoelectric element 4: Friction contact part 5: Cylindrical part 6: Flange part 7: Moving body 8: Spring receiving part 9: Pressure spring 10: Main-body part 11: Shaft 12: Disc 13: Contact spring structure 14: Cooling auxiliary member (liquid)
15: Cooling auxiliary member (elastic body)

Claims (4)

A vibrating body having an electro-mechanical energy conversion element, and a moving body in pressure contact with the vibrating body,
A vibration type actuator that frictionally drives the moving body by a vibration wave excited by the vibrating body by applying an alternating signal to the electro-mechanical energy conversion element, and moves the moving body relative to the vibrating body; There,
A contact spring structure having a friction contact portion that frictionally contacts either one of the vibrating body or the moving body,
A gap is formed between the contact spring structure and the main body constituting the vibrating body or the moving body,
A vibration type actuator characterized in that a heat radiating means for radiating heat generated in the friction contact portion is interposed in the gap.   The vibration type actuator according to claim 1, wherein the heat radiating unit includes a configuration in which one of a liquid and an elastic member is interposed in the gap.   The heat dissipating means has a configuration in which a heat conducting member formed on the main body portion side of the vibrating body or the moving body and having a non-contacting proximity surface with the friction contact portion is interposed in the gap. The vibration type actuator according to claim 1.   4. The vibration type actuator according to claim 3, wherein either one of a liquid and an elastic member is interposed between the friction contact portion and the non-contact proximity surface in the gap.

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