JPH0442787A - Oscillatory wave motor - Google Patents

Abstract

PURPOSE:To fix a moving unit solidly to an output shaft without providing an elastic sheet between them by a method wherein the moving unit is composed of a molded unit made of composite resin an fitted and fixed to the output shaft with an elastic element therebetween without employing an intermediate metal member made of metal such as aluminum alloy. CONSTITUTION:Thermosetting resin which has a glass transition point not lower than 100 deg.C and contains carbon fibers (or graphite fibers, carbon whiskers or potassium titanate fibers) is injection-molded so as to have the reinforcing fiber material oriented along the circumferential direction of a molded annular moving unit 207. Thus the moving unit 207 made of composite resin containing the reinforcing fibers which are oriented along the circumferential direction is formed by an injection molding method. After the surface of the moving unit 207 is polished, the moving unit 207 is assembled into an oscillatory wave motor by fixing it to the output shaft 110 of the motor with a rubber-like elastic element 217 therebetween.

Description

Detailed Description of the Invention (Field of Application in Industry A) The present invention generates a progressive vibration wave in a vibrating body by applying a voltage to an electro-mechanical energy conversion element, and generates a progressive vibration wave between the vibrating body and the member in contact with the vibrating body. The present invention relates to a vibration wave motor that causes relative movement by friction drive, and particularly to a large vibration wave motor.

(Prior Art) A vibration wave motor is composed of a vibrating body that generates progressive vibration waves and a moving body that is brought into frictional contact with the vibrating body. The specific configuration of the system will be explained below based on FIG.

The vibrating body 2 that generates progressive vibration waves is formed by fixing a group of thin piezoelectric elements 1 having the same annular shape to the back surface of an annular elastic body made of, for example, stainless steel. Since the surface of this elastic body forms a friction drive surface that is in contact with the moving body 7, it is sprayed with a superhard material made of, for example, tungsten carbide and cobalt, and then polished so that it has the necessary characteristics as a friction drive surface. It is considered a hard sliding surface.

On the other hand, the movable body 7 that comes into pressure contact with the sliding surface of the vibrating body is formed by fixing and laminating a sliding body 6 on an annular support body 5 made of metal such as aluminum alloy, for example. Generally, those created as follows are used. That is, thermoplastic resins with a glass transition point of 100°C or higher, specifically polyimide (PI), polyamideimide (PA)
I), polyetherimide (PEI), polyetheretherketone (PEEK), polyethersulfone (P
ES), polyarylate (PAR), polysulfone (
PSF), aromatic polyamide (PA), or other heat-resistant resin filled with a reinforcing material such as carbon fiber is used as a material to make a cylindrical molded product, and then this cylindrical molded product The above-mentioned sliding body 6 is made by cutting out a ring disk shape with a thickness of about 1 mm perpendicular to the axis. The ring-disc-shaped sliding body 6 made of a composite resin material made in this way is fixed to the support 5 made of aluminum alloy or the like with a heat-resistant adhesive, and then the composite resin sliding body 6 The dimensions were determined by cutting the inner diameter, outer diameter, and thickness of the sliding surface, and the sliding surface was further polished to obtain the moving body 7.

In the example of FIG. 4, the movable body 7 includes an intermediate member 15
The moving body 7 is coupled via an elastic sheet member 17 made of rubber, which blocks vibrations generated in the moving body 7 when the moving body 7 is frictionally driven by the progressive vibration waves of the vibrating body 2. This is because the power is not transmitted to the intermediate member 15, the output shaft 10, or other power transmission parts.

Furthermore, in the above-mentioned conventional vibration wave motor, a composite resin sliding body whose matrix resin is a thermoplastic resin with a glass transition point of 100°C or higher is used to form the sliding surface of the moving body. This is because the material properties of the resin have low temperature dependence, and this prevents torque reduction due to softening of the resin material when the temperature rises when the motor is driven, thereby stabilizing the performance of the motor.

In addition, reinforcing materials such as carbon fiber are added to the composite resin sliding body because of the properties of the sliding surface of the moving body that comes into contact with the carbide sliding surface on the vibrating body side, which is made of tungsten carbide and cobalt, for example. It is important to ensure that the sliding surface of the moving body has sufficient wear resistance, and that the elastic modulus or thermal conductivity of the sliding body is kept stable at all times, and that the sliding surface of the moving body has sufficient wear resistance even when driven for long periods of time with a large load torque. This is to improve the output and efficiency of the vibration wave motor.

(Problems to be Solved by the Invention) As mentioned above, a heat-resistant thermoplastic resin with a glass transition point of 100° C. or higher is used as a matrix resin as a member for providing a sliding surface of a moving body in a vibration wave motor. Conventional vibration wave motors that use a sliding body made of reinforced composite resin filled with carbon fiber, etc. have good wear resistance even when the moving body is frictionally driven for a long time with a large torque against the ultrahard material surface of the vibrating body. was high, and motor performance such as output and efficiency also showed high values.

However, on the other hand, the vibration wave motor of the conventional configuration has a torque unevenness of 5% or more with respect to the rated torque when the motor is continuously operated at the rated torque.

Also, for example, 4 kg-cm determined as the rated operating condition.
, When continuous operation was started at 100 rpm, there was a problem in that the temperature of the friction sliding surface increased and torque undulation occurred.

Furthermore, when driving with no load or low load torque, so-called "squeal" which is presumed to be derived from sliding friction.
There was also the problem that the following phenomenon occurred.

In addition to the above-mentioned problems with the characteristics of vibration wave motors, since the sliding body is cut out from a cylindrical molded product, when manufacturing the moving body, it is difficult to integrate the cut out material of the sliding body with adhesive. First, the adhesive surface of the support to be attached is polished to an appropriate roughness, then a heat-resistant adhesive is applied, and the two are left in pressurized contact for several hours in an electric furnace at, for example, 60°C, and then In addition, a series of processing is required, including cutting the outer diameter, inner diameter, etc. to obtain the dimensions, and finally polishing the sliding surface to finish it, which takes time and effort due to manufacturing problems. Another problem was that it was difficult to reduce costs.

In addition, a structural problem with vibration wave motors is that when extracting rotation from a moving body that is in pressurized contact with a vibrating body,
Since vibration is transmitted to the output shaft 10, the moving body 7 and the output shaft lO
It is necessary to insert an elastic sheet 17 made of rubber or an intermediate member 15 made of aluminum alloy between the parts, which increases the number of man-hours for processing and increases the number of parts, resulting in a higher cost of the product. there were.

The inventors of the present invention have conducted extensive research and development to solve these problems. In addition, we have found that the torque waviness can be improved by using a material with higher heat resistance.

Furthermore, we considered reducing the number of parts and the number of processing steps by omitting the elastic sheet without transmitting the vibrations of the moving body to the output shaft.

The present invention aims to solve the various problems in the conventional example as described above, and was made based on the various findings mentioned above. One of the purposes is to solve the problem of torque fluctuation or It is an object of the present invention to provide a vibration wave motor having a novel configuration that can reduce torque unevenness and eliminate "squeak" when driving at no load or low load.

Another object of the present invention is to enable the movable body and the output shaft to be fixed together without interposing an elastic sheet, thereby satisfying the improved characteristics required for the movable body of the vibration wave motor. It is an object of the present invention to provide a novel vibration wave motor that can be manufactured by easy machining.

(Means for Solving the Problems) The vibration wave motor of the present invention, which has been made to achieve the above object, is characterized by a vibrating body that generates a progressive vibration wave, and a vibrating body that is in contact with this vibrating body to cause the vibration wave motor to move. A vibration wave motor includes a moving body that is friction-driven and rotated by vibrational vibration waves, and a rotation shaft that is connected to the moving body so as to extract the rotation of the moving body, wherein the moving body has a glass transition point. It is formed of a composite resin molded product made of a thermoplastic resin of 100° C. or higher as a matrix resin and blended with at least one of a lubricant and a reinforcing material, and the rotating shaft has an intermediate member made of metal such as aluminum alloy. The structure is such that they are connected and fixed through an elastic body without using any other means.

In the above, the reinforcing material is a non-fibrous reinforcing material such as amorphous or spherical carbon graphite, glassy carbon,
Alternatively, it may be any fibrous reinforcing material such as carbon fiber, graphite fiber, carbon whisker, potassium titanate whisker, etc. If the reinforcing material is a non-fibrous reinforcing material, the filling amount is 5 to 30% by weight. %, and in the case of fibrous reinforcement, the weight ratio is 10 to 40%.
% loading is often preferred.

In addition, when using a fibrous reinforcement material as a reinforcing material, the reinforcing fibers can be provided by injection molding such as one-point side gate method so that the longitudinal direction of the fibers is oriented in the sliding direction of the sliding surface. preferable. This equalizes the surface texture and surface strength, reducing torque unevenness at least during rated operation, and this orientation provides anisotropy in the elastic modulus in the circumferential direction and the normal direction. Effective in reducing "drip" during no-load operation.

The lubricant filled in the moving body of the present invention is at least one type of fluororesin, or at least one type of fluororesin and at least slm of lead oxide. Examples of such lubricants include fluororesins such as tetrafluoroethylene resin (PTFE) and lead oxides such as -lead oxide (pbo). Fluororesin has a weight ratio of 5 to 40
%, and the content of lead oxide is preferably 30% or less.

Furthermore, the integrally molded moving body made of the composite resin of the present invention is further coated with molybdenum (MO) powder of 15% or less or tungsten (W) powder of 40% or less by weight to improve wear resistance. Can be filled as reinforcement.

As described above, one of the features of the present invention is that the moving body is an integrally molded product made of a composite resin in which a thermoplastic resin with a glass transition point of 100° C. or higher is used as a matrix resin, and a lubricant and/or reinforcing material is blended with the thermoplastic resin. It lies in the fact that it is formed as.

Another feature is that the movable body, which is integrally molded with such a composite resin member, is fixed to the rotating output shaft via an elastic body without using an intermediate metal member such as an aluminum alloy. It's there.

The thermoplastic resin used to satisfy the above characteristics of the present invention has a glass transition point of 100°C or higher, preferably
Resin at 140°C or higher, specifically, for example, polyimide (
PI), polyamideimide CPAI), aromatic polyester resins exhibiting liquid crystallinity, etc. Particularly preferred are liquid crystalline aromatic polyester resins such as Vectra (trade name: manufactured by Celanese), Xydar (trade name) : manufactured by Dartco), and ECONOL (trade name; manufactured by Sumitomo Chemical).

The movable body of the vibration wave motor of the present invention does not require many processes and has a significant cost reduction compared to the conventional movable body in which a ring-disc-shaped sliding body is cut out from a cylinder and bonded to a metal support under pressure. Cost reduction can be realized.

Note that the moving body of the present invention is polished as necessary to obtain the flatness and surface roughness necessary for frictional drive with the vibrating body.
Preferably, the fibrous reinforcing material appears on the sliding surface so as to eliminate the difference between the initial characteristics and the aging characteristics of the motor. In addition, in order for the vibrating body to have sufficient wear resistance against the sliding surface of the moving body, the sliding surface of the vibrating body must be replaced with a hard surface made of a superhard material made of tungsten carbide and cobalt (for example, Vickers hardness Hv). = approximately 1200).

(Example) The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of a vibration wave motor according to the present invention.

In this figure, 2 is an annular vibrating body substrate made of a metal member such as stainless steel, and on the back side of the substrate, a group of thin annular piezoelectric elements 1 are connected concentrically with a heat-resistant epoxy resin adhesive. The sliding surface on the front side has a comb-like shape with a large number of grooves cut in the axial direction in the circumferential direction in order to increase the vibration amplitude of the progressive vibration wave.

Reference numeral 3 denotes a housing made of a metal material with good thermal conductivity, and a first ball bearing 11 is provided in the center of the housing.
The vibrating body 2 is fixed with a screw 4 concentrically with the axis of a ball bearing 11.

Reference numeral 110 denotes an output shaft having a flange portion 110C formed in the middle, one end side 1108 of which is supported through the inner ring of the first ball bearing 11 so as to be able to slide in the axial direction, and the other end side 110b is an output shaft. , is axially slidably and rotatably penetrated through an inner ring of a second ball bearing 12 (described later) and a shaft hole of a spring pressure adjusting nut member 18 (described later).

Reference numeral 207 is a disk-shaped moving body which is fixed by a screw 116 with a rubber-like bag body 217 sandwiched between the flange portion 110C of the output shaft 110, and its sliding surface contacts the sliding surface of the vibrating body 2. However, a coiled compression spring member 14 elastically mounted between the flange portion 11Oc of the output shaft 110 and the second ball bearing 12 is pressed into contact with the axial load generated by the coiled compression spring member 14.

Reference numeral 8 denotes a housing cover of the vibration wave motor, which is fixed to the housing 3 with screws 9. A second ball bearing 12 is fitted into the bearing fitting hole 8b formed in the center thereof so as to be able to slide in the axial direction, and a screw portion 8C is further provided on the inner circumferential surface of the bearing fitting hole 8b. A spring pressure adjusting nut member 18 is screwed onto the spring pressure adjusting nut member 18. The spring pressure adjusting nut member 18 is in contact only with the outer ring 12a of the second ball bearing 12, and the inner ring 12b of the second ball bearing 12 is provided to be slidable in the axial direction and rotatable with respect to the output shaft 110. and two small holes 18a, 18 formed in the spring pressure adjusting nut member 18.
For example, by inserting the insertion rod of a jig (not shown) having two wooden insertion rods at the tip into b and turning it clockwise, the spring pressure adjustment nut member 18 is screwed to the left in the figure. While moving forward, the second ball bearing 12 is pushed in the same direction to compress the compression spring member 14 to increase the spring force, and when turned in the opposite direction, the compression spring member 14 is expanded to weaken the spring force. This makes it possible to adjust the axial load of the output shaft 110 by the deflection of the spring. After adjusting the axial load of the output shaft 110, adhesive is normally poured into the small hole 8a of the housing cover 8 to fix the outer ring 12a of the second ball bearing 12 to the housing cover 8.

Further, a spacer 13 that contacts only the inner ring 12b of the second ball bearing 12 is arranged between one end of the compression spring member 14 and the ball bearing 12 of 'i42.
3, one end of the compression spring member 14 is in contact with the output shaft 110, allowing the output shaft 110 to rotate smoothly without any hindrance. In addition,
The compression spring member 14 preferably has a spring constant as small as possible in order to reduce fluctuations in axial load with respect to deflection.

Reference numeral 119 denotes a second coil-shaped compression spring, in which a first ball is inserted between the inner ring 11a of the first ball bearing 11 and the flange portion 110c of the output shaft 110 in order to eliminate rotational wobbling of the pressure shaft 110. It is provided to eliminate play in the bearing.

As shown in FIG. 2, the piezoelectric element group 1 of the vibrating body 2 described above includes a driving piezoelectric element group 1a and a BII piezoelectric element group 1b, each of which has been polarized as shown, and detects the vibration state. It is composed of two piezoelectric element ICs for vibration detection and a common electrode 1d for grounding, and the B piezoelectric element group 1b has 1 wavelength (λ) of the frequency to be excited in the circumferential direction with respect to the A piezoelectric element group 1a. They are arranged at a pitch shifted by /4.

By applying frequency voltages having phases different by 90° to the A piezoelectric element group 1a and the B piezoelectric element group 1b, progressive vibration waves are generated on the surface of the vibrating body 2, and the above-mentioned vibration wave is generated on the surface of the vibrating body 2. The movable body 107 brought into pressure contact is frictionally driven to rotate the output shaft 110 via the intermediate member 15.

The material of the vibrating body is preferably martensitic stainless steel, which approximates the thermal expansion coefficient of the piezoelectric element group 1 in the circumferential direction and has a relatively small thermal expansion coefficient. This material has a small internal loss and is therefore suitable as a material for the vibrating body. The sliding surface of the vibrating body is a hard surface coated with tungsten carbide and cobalt (H
It is preferable to form a hard surface (Hv=1200 after annealing) of an inexpensive neckerlin alloy containing, for example, silicon carbide (S i C).

Regarding the vibration wave motor having the above configuration, the moving body 10 of the present invention
In order to evaluate the composite resin material forming No. 7, a moving body having the formulation shown in Table 1 below was formed.

No. table However, each member in the table is as follows.

PI: Polyimide FAI: Polyamideimide PEI: Polyetherimide PEE: Polyetheretherketone PES
: Polyethersulfone aromatic PA : Aromatic polyamide LCP : Totally aromatic polyester PTFE : Polytetrafluoroethylene carbon fiber : Average wire diameter 7 μm 1 average length 300 μm.

Carbon piece: average particle size 10 μmMO=
Molybdenum 5 μmGRP
: Amorphous carbon graphite Figure 3 is
The ring-shaped moving body 207 of this example explained in the figure is made of carbon fiber (
A manufacturing example will be described in which the reinforcing material is molded by injection molding to orient the fibrous reinforcing material in the circumferential direction of the ring.

For example, FIG. 3(a) shows a one-point injection molding method, in which a thermoplastic resin material containing fibrous reinforcement is injected from one side gate into a mold having a ring-disk cavity. An example in which the contained fibers are oriented in the circumferential direction by the flow of the material, and FIG. 3(b) shows an injection molding method using a one-point pin gate method, in which thermoplastic resin is applied to the bonding surface of the ring disk from a one-point pin gate. This shows an example in which a resin material is injected and the contained fibers are similarly oriented in the circumferential direction by the flow of the material.

By these injection molding methods, a composite resin moving body 207 filled with fibrous reinforcing material is formed with the fibers oriented in the circumferential direction.

The moving body was molded using a single-point side gate injection molding method, and the orientation of the filled carbon fibers, which were the fibrous reinforcing material, was observed using a stereomicroscope, and the longitudinal direction was aligned along the circumferential direction of the sliding surface. As a result of calculating Beharman's orientation parameter for the carbon fibers, it was confirmed that the orientation of the carbon fibers in the sliding body was at least 70%.

After polishing the surface of the movable body 207 having the configuration shown in Table 1 above, it is fixed to the output shaft 110 via the rubber-like elastic body 217 and incorporated into the vibration wave motor having the configuration shown in FIG. The performance of the motor was tested.

As a result, it was confirmed that the torque waviness was more improved in higher thermoplastic resins.

In addition, in the above-mentioned moving body, since the sliding surface properties and surface strength are essentially uniform in the non-fiber-reinforced moving body, the torque unevenness is less than in the example using the conventional moving body. was confirmed to be improved. In addition, in the moving body filled with the above-mentioned fibrous reinforcing material, the carbon fibers are oriented in the circumferential direction of the sliding surface, and the elastic modulus in the normal direction is smaller than the elastic modulus in the circumferential direction. This is thought to be due to the uniform surface strength, but the torque unevenness was significantly reduced and improved.

In addition, the occurrence of "squeal" when there is no load or under low load is caused by the fact that non-fiber-reinforced composite resin moving bodies have smaller and more uniform material properties such as elastic modulus and hardness than conventional moving bodies. As a result, "squealing" is less likely to occur.

It was confirmed that the "squeal" phenomenon was even more suppressed in fiber-reinforced composite resin mobile objects made by injection molding.

In addition, in cases where aromatic polyester resin is used as the matrix resin, ``squeal'' occurs more often than with other composite resin moving bodies, regardless of whether it is filled with non-fibrous or fibrous reinforcing material. was further suppressed. This is thought to be because the molecules of the fiber reinforcement solidify while oriented in the direction of flow, thus exhibiting elastic anisotropy.

When comparing the output of a vibration wave motor at a constant m4kgcm, for example, the weight ratio of carbon fiber to aromatic polyester is 30.
% filled material is 7. OW or more is the largest, followed by a series of thermoplastic resins with a weight ratio of carbon fiber of 20% or 30%.
% loading of materials ranges from 52 to 5.7 W, with a series of thermoplastic resin filled fibrous reinforcement materials ranging from 52 to 5.7 W.
-55 W, and ranged from 4.7 to 5.2 W for a series of thermoplastic resin filled non-fibrous reinforcement materials.

All of the above materials satisfied the rated output (4.1W).

The bulk elasticity of the boxwood elastic portion of the moving body 207 made of composite resin was made equal to the bulk elasticity of the top elastic portion of the conventional aluminum alloy BvJ body shown in FIG.

(Effects of the Invention) As explained above, the vibration wave motor of the present invention uses a thermoplastic resin having a glass turning point of 100° C. or more instead of the thermoplastic resin conventionally used to form the sliding body of a moving body. Preferably, a thermoplastic resin having a temperature of 140° C. or higher, particularly preferably a liquid crystalline aromatic polyester, is used as the matrix resin,
In addition, the moving body is made of a composite resin material containing non-fibrous or fibrous reinforcing material and lubricants such as tetrafluoroethylene and lead oxide, and is integrally molded by injection molding. Since this moving body is fixed to the output rotating shaft, it is possible to reduce torque fluctuations or torque unevenness during rated operation of the vibration wave motor, and to reduce drive "squeal" during no load or low load. In addition to being able to avoid this problem, the moving body can be formed as an injection molded product alone, eliminating the need for the conventional process for forming the moving body, resulting in a new vibration wave motor that can reduce costs. It has the effect of being able to provide

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an outline of the configuration of a vibration wave motor constructed by applying the present invention, and FIG. 2 is a plan view illustrating the arrangement of a group of piezoelectric elements constituting the vibrating body. . 83 Figures (a) and (b) are diagrams for explaining an injection molding method for forming a moving body. FIG. 4 is a longitudinal sectional view showing an example of the configuration of a conventional vibration wave motor. 1: Piezoelectric element group 2 Vibrating body 107: Moving body Figure al +bl Figure Figure

Claims (7)

[Claims] 1. A vibrating body that generates progressive vibration waves, a moving body that contacts this vibrating body and is rotated by friction drive by the progressive vibration waves of the vibrating body, and is connected to the moving body so as to extract the rotation of the moving body. In the vibration wave motor equipped with a rotating shaft, the movable body has a thermoplastic resin having a glass transition point of 100° C. or higher as a matrix resin, and at least one of a lubricant and a non-fibrous reinforcing material is blended therein. A vibration wave motor, characterized in that it is formed of a molded product made of composite resin, and is connected and fixed to the rotating shaft via an elastic body. 2. 2. The vibration wave motor according to claim 1, wherein the non-fibrous reinforcing material is amorphous or spherical and at least one of carbon graphite and glassy carbon. 3. 2. The vibration wave motor according to claim 1, wherein a transition metal powder such as molybdenum or tungsten is blended into the matrix resin as a non-fibrous reinforcing material. 4. A vibrating body that generates progressive vibration waves, a moving body that contacts this vibrating body and is rotated by friction drive by the progressive vibration waves of the vibrating body, and is connected to the moving body so as to extract the rotation of the moving body. In the vibration wave motor equipped with a rotating shaft, the moving body is made of a composite resin in which a thermoplastic resin having a glass transition point of 100° C. or higher is used as a matrix resin, and at least one of a lubricant and a fibrous reinforcing material is mixed therein. 1. A vibration wave motor, characterized in that the vibration wave motor is formed of a molded product manufactured by the company, and is connected and fixed to the rotating shaft via an elastic body. 5. 5. The vibration wave motor according to claim 4, wherein the fibrous reinforcing material is at least one of carbon fibers, graphite fibers, carbon whiskers, and potassium titanate whiskers. 6. 5. The vibration wave motor according to claim 4, wherein the blended fibrous reinforcing material is oriented in the moving direction of the moving body in the matrix resin. 7. 5. The vibration wave motor according to claim 1, wherein the lubricant is at least one type of fluororesin, or at least one type of fluororesin and at least one type of lead oxide.