JPH07284283A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To suppress the generation of the low-order resonance of a vibrator causing 'ringing' of a vibration wave motor by filling a low-attenuation material into the internal void of a baked-alloy vibrator at a specific ratio. CONSTITUTION:A vibrator 10 is made of, for example, iron baked alloy (iron containing 0.2-1.0% carbon and 1-5% copper) and a low-attenuation material (for example, copper) is melted and filled into the void of the baked alloy by 0-80% in terms of volume ratio. Also, the filling rate of the low-attenuation material is constituted to be larger as the material is away from the vibrator 10 and a sliding surface side. Therefore, the material is so structured as to prevent stick slip due to low-order vibration from occurring easily, thus effectively suppressing the generation of a low-order resonance of the vibrator 10 causing generation of 'ringing' of the motor.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vibration wave motor.

[0002]

2. Description of the Related Art A vibration wave motor using vibration energy of a piezoelectric element or the like as a power source is known, and has already been used as a drive source for optical devices such as cameras. There are various types of vibration wave motors, but the following is a conventional example of a known vibration wave motor used in optical equipment.
And FIG. 7 will be described.

In FIGS. 6 and 7, reference numeral 9 is a vibrating body, that is, a stator, 3 is a moving body, that is, a rotor, and a rotor 9 is provided on a stator 9 formed by joining a ring-shaped elastic body 1 to a piezoelectric ceramics 2. Is pressed by the pressure spring 5 via the shaft 4. The elastic body 1 is supported by a support plate 7 via a vibration insulator 6 such as felt.
Since the shaft rod 4 is rotatably supported by the bearing 8 and the shaft rod 4 and the rotor 3 are integrally connected, the rotor 3 can rotate without touching the shaft rod 4 as a center of rotation. You can When a two-phase AC electric field whose time phase is shifted by π / 2 is applied to the piezoelectric ceramics 2 from a drive circuit (not shown), a progressive vibration wave is generated in the stator and the rotor 3 vibrates due to frictional force with the stator. It rotates in the opposite direction of the wave.

The elastic body 1 has a large number of slits 1a provided at equal or unequal intervals on the sliding surface side in contact with the rotor 3 in order to improve the efficiency of the motor.
As the material of the elastic body 1 including the slits 1a, the base 1b, and the protrusions 1c, a metal with a small energy loss due to vibration (a metal with a small vibration damping), such as stainless steel, carbon steel, brass, or phosphor bronze, was used.

It is considered that such a shape and material of the elastic body 1 are indispensable conditions for designing a high performance vibration wave motor.

Conventionally, since the slits 1a provided in the elastic body 1 are formed by cutting one by one by machining, the processing cost of the elastic body 1 is increased and the cost of the vibration wave motor is also increased. There was a problem that

In order to solve this problem, it has been proposed to form the elastic body 1 by a forging method.

However, in forging, there is a limit in processing in that the pitch of the slits 1a and the depth of the slits are stably formed, and the number of slits and the depth of the slits that can maintain the currently required motor performance are limited. It is not possible to form it, and in terms of material, it is required that it is a material with good malleability in order to forge, but stainless steel and brass suitable as a vibrating body are not suitable for forging. It was difficult to manufacture an elastic body by forging.

Therefore, the present inventor can fabricate the elastic body by using a powder sintered alloy and fill the pores in the sintered alloy with a substance having a small vibration damping rate, so that the elastic body can be manufactured without cutting. A vibrating body has been proposed (see Japanese Patent Laid-Open No. 4-109878).

[0010]

Since the vibration wave motor has a desirable characteristic of generating a large torque at a low speed, it is expected that its field of use will be expanded in the future. Has a short history, there is still a problem to be solved for the motor,
In particular, there are many problems to be solved in mass production.

As one of such problems, recent studies have revealed that a conventional vibration wave motor is highly likely to cause a "squeal" phenomenon. This "squeaking" phenomenon is an intermittent "squeaking noise" in the high rpm range.
It is considered that this "squeaking noise" is caused by stick-slip between the rotor (moving body) and the vibrating body (stator). In addition, this stick-slip has poor flatness on the mutual sliding surface between the rotor and the stator, uneven pressure distribution on the mutual pressure contact surface between the rotor and the stator, and on the mutual sliding surface between the rotor and the stator. It is considered that low-order resonance occurs in the stator due to factors such as instability of the frictional state, and this low-order resonance occurs.

In order to prevent the occurrence of such "squealing", it is necessary to solve the above-mentioned problems (1) to (3), and in order to solve these problems, the mutual sliding surface between the rotor and the stator must be solved. It is necessary to take measures such as further improving the flatness and improving the pressing mechanism so as to eliminate uneven pressure distribution on the mutual sliding surface between the rotor and the stator. Such measures include machining measures such as improving the machining accuracy of the rotor and the stator, and design measures of the mutual pressure mechanism between the rotor and the stator. It is also necessary to take measures regarding such matters.

Although the prior art of the present inventor disclosed in the above-mentioned patent publication is suitable for manufacturing a vibrating body at a lower cost and with higher accuracy than conventional ones in mass production of a vibrating wave motor, Since it does not solve the problem of "", a vibration wave motor without "squeal" cannot be realized even by the technique disclosed in this publication.

In order to prevent "squealing" from occurring in the vibration wave motor, it is conceivable to attach a vibration damping material such as rubber to the vibrating body, but this means dampens the vibration of the vibrating body. Therefore, the output of the motor is decreased, which is not suitable for practical use.

An object of the present invention is to provide a vibration wave motor having a vibrating body which is less likely to cause "squeaking" and which is lower in cost and more accurate than conventional ones.

[0016]

The vibrating body made of a sintered alloy proposed by the present inventor in the above-mentioned patent publication has many holes therein, and the holes are vibration damping materials. It has the function as. Therefore, in the above-mentioned prior art, in order to reduce the vibration damping effect due to the holes and to enhance the mechanical toughness of the vibrating body, copper is not used in all the through holes except the independent holes in the holes. Filling with a low damping material weakens the vibration damping effect of the vibrating body, while increasing the rigidity of the vibrating body (made of sintered alloy), the Q value (resonance sharpness)
Was close to the Q value of the conventional stainless steel vibrator.

The present inventor believes that it is possible to prevent low-order resonance from occurring in the vibrating body made of the sintered alloy by utilizing the means used in the prior art.
The present invention has been constructed based on this idea.

That is, the vibration wave motor of the present invention has a vibrating body made of a sintered alloy, and by filling the internal holes of the vibrating body with a low damping material at a predetermined ratio, the vibration wave motor It is characterized in that it is possible to effectively suppress the occurrence of low-order resonance of the vibrating body, which causes the occurrence of "squeaking".

[0019]

The vibration wave motor of the present invention has a vibrating body made of a sintered alloy, and 0 to 80% (volume ratio) of the internal pores of the vibrating body are filled with a low damping material. Since the filling rate of the low-damping material is configured to increase as the distance from the sliding surface side with the moving body increases, the damping effect of low-order vibration is large at the sliding contact surface with the moving body, Therefore, the structure is such that stick slip due to the low-order vibration is unlikely to occur in the moving body.

[0020]

EXAMPLES Examples of the present invention will be described below with reference to FIGS. The mechanical structure of the vibration wave motor of the present invention is exactly the same as that of the conventional vibration wave motor, and only the constituent materials, mechanical properties, and physical structure of the vibrating body are different from those of the conventional example. The illustration of the mechanical structure of the wave motor will be applied correspondingly to FIGS.

The vibrator used in the vibration wave motor of the present invention is made of an iron-based sintered alloy (iron containing 0.2 to 1.0% carbon and 1 to 5% copper). The pores of the sintered alloy were infiltrated with 0 to 80% by volume of copper.

In order to clarify the properties of the vibrating body used in the vibration wave motor of the present invention, the first vibrating body in which the pores of the sintered alloy are infiltrated with 80% by volume of copper, A second vibrating body in which the pores of the sintered alloy are not filled with copper and a third vibrating body made of conventional stainless steel (SUS420J2) are manufactured, and three types of vibration wave motors having the vibrating body are provided. It manufactured and compared these. The porosity of the alloy is 10 to 15%. Further, since the sintered alloy has about 20% of the total number of independent pores, and the independent pores cannot be infiltrated with copper, the remaining about 80% of the infiltrateable through holes are filled with copper. The first vibrator was constructed by infiltration.

Each of the vibrating bodies is formed in the shape shown in FIG. 7, and a piezoelectric element is bonded to the back surface of each vibrating body (that is, the surface opposite to the sliding contact surface with the moving body). Has been done.

FIG. 2 is a graph showing the results of examining the vibration characteristics of each vibrator by changing the frequency of the AC voltage applied to the piezoelectric elements of the first to third vibrators.

In FIG. 2, the horizontal axis represents the frequency of the AC voltage applied to the piezoelectric element of each vibrating body, and the vertical axis represents the vibration admittance of each vibrating body when an AC voltage having a constant frequency is applied to the piezoelectric element. is there. Note that FIG. 2 shows the vibration admittance when the frequency of the applied voltage is swept in the vicinity of the eighth resonance frequency (vibration mode order when the vibration wave motor is driven) of each vibrator.

FIG. 2 (a) is a graph showing the vibration characteristics of the first vibrating body of the present invention (that is, the vibrating body made of a sintered alloy in which copper is infiltrated in 0 to 80% of the pores) as vibration admittance. 2 (b) is a graph showing the vibration characteristics of the second vibrating body of the present invention (that is, a vibrating body made of a sintered alloy that does not infiltrate copper) as vibration admittance, and FIG. 2 (c) is a conventional graph. 6 is a graph showing vibration characteristics of a third vibrating body made of stainless steel as vibration admittance.

As shown in FIG. 2, the vibration admittance of the conventional vibrating body made of stainless steel is highest, followed by the first vibrating body of the present invention, and the lowest vibration admittance is a sintered alloy without copper infiltration. The second vibrating body made in this order.

Next, FIG. 1 shows the number of rotations at which "squealing" occurs for the three types of vibration wave motors constructed by using the three types of vibrators.

In FIG. 1, point A indicates the number of revolutions at which "squealing" of a vibration wave motor composed of a sintered alloy vibrating body without copper infiltration (that is, the second vibrating body) starts, B
Is the rotational speed of the "squealing" start of the vibration wave motor constituted by using the first vibration body (that is, the vibration body made of a sintered alloy having 80% copper infiltration), and point C is the conventional vibration body made of stainless steel. "Squealing" starting rotation speed of a vibration wave motor configured using
Is shown.

In FIG. 1, as the vibration wave motor of the present invention, the "squealing" of the vibration wave motor using the first vibrating body in which 80% by volume of copper is infiltrated in the pores of the sintered alloy. "Only the starting point is indicated by the point B, but the result that the" squealing "starting point is represented by the point along the straight line L in FIG. 1 is obtained even though the infiltration rate of copper is set to an arbitrary value of 80% or less. Has been.

As is apparent from FIG. 1, the vibration wave motor composed of the first and second vibrating bodies made of sintered alloy has a higher speed range than the vibration wave motor composed of the conventional vibrating body made of stainless steel. It has been proved that the car can be driven without "squeaking". Therefore, the vibrating wave motor of the present invention having the vibrating body made of the sintered alloy is more advantageous than the conventional vibrating wave motor not only in the manufacturing cost of the vibrating body but also in the effect of preventing the "squeal" from occurring. I understood.

However, since the vibrating body made of the sintered alloy has a lower vibration admittance than the vibrating body made of the conventional stainless steel, there is a possibility that the operating characteristics as the vibration wave motor may be deteriorated, and it is necessary to verify this point. Therefore, each of the above three types of vibration wave motors is operated under the same conditions, and TN
(Torque-rotation speed) characteristics were examined.

FIG. 3 is a graph showing the results of TN characteristics and motor efficiency obtained by the operation test on the above-mentioned three kinds of vibration wave motors, and FIG. 3 (a) is made of a sintered alloy without copper infiltration. Efficiency and T-N characteristic diagram of vibration wave motor composed of second vibrating body, FIG. 3 (b) is efficiency and T-N characteristic diagram of vibration wave motor composed of conventional vibrating body made of stainless steel ,. In both figures, curve K represents the change in efficiency. Further, these operation characteristic tests were conducted in a rotation region where the vibration wave motor is actually used, and show no-load characteristics.

Although the TN characteristic diagram of the vibration wave motor constituted by the first vibrating body in which 80% of the pores of the sintered alloy is infiltrated with copper is not shown,
TN of a vibration wave motor constituted by the first vibrating body
The characteristics are better than those of a motor having a vibrator without copper infiltration.

Comparing FIG. 3 (a) and FIG. 3 (b),
It can be seen that there is almost no difference between the two in terms of TN characteristics and efficiency, and that the vibration wave motor having the second vibrating body made of a sintered alloy has higher efficiency in the high torque range. Therefore, the vibration wave motor having a vibrating body made of a sintered alloy has a lower vibration admittance than that of a stainless steel vibrating body, but its operating characteristics are not inferior to conventional vibration wave motors. Also proved to be highly practical.

From the results shown in FIGS. 1 and 2, "squeal"
It has been proved that the vibration wave motor having the second vibrating body made of a sintered alloy that does not infiltrate copper is most effective in preventing the generation of the vibration wave. Although it has been proved that it is not inferior to the vibration wave motor, the vibrating body made of a sintered alloy in which copper is not infiltrated into the pores is the first vibrating body (copper in the pores in a volume ratio of 0 to 0). Mechanical strength (especially toughness) compared to 80% infiltrated sintered alloy vibrator)
Since the vibration resistance is considerably low, the durability of the vibrating body made of a sintered alloy without copper infiltration is considerably lower than that of the conventional vibrating body made of stainless steel, and it is clear from the experiments conducted by the present inventors that it is not suitable for high output. It has become.

On the other hand, it has been clarified that the first vibrating body made of a sintered alloy in which the holes are infiltrated with copper has high toughness and rigidity, and there is no problem in practical use. .

As described above, as a result of examination from the three aspects of "squeal", operating characteristics, and strength, the vibration wave motor of the present invention has the same operation characteristics as the conventional vibration wave motor,
In addition, it has been found that an improved vibration wave motor with less risk of "squealing" can be realized.

As described above, the cause of the "squeal" of the vibration wave motor is known to be caused by the stick slip on the mutual sliding contact surface between the vibrating body and the moving body. It is necessary not to cause low-order resonance in the contact surface. Therefore, it is considered that the closer to the sliding contact surface of the vibrating body (the mutual pressure contact surface with the moving body), the greater the damping effect of the low-order vibration is, which is effective in preventing the "squeal".

A second embodiment constructed on the basis of such an idea is shown in FIGS. 4 and 5. The vibrating body 10 of the present embodiment is also made of the above-mentioned sintered alloy, and the filling rate (infiltration rate) of copper with respect to the void portion in the projection portion 10a of the sliding contact surface of the vibrating body 10 is lowered to reduce the vibrating body. The filling rate of copper is increased on the back surface side (base portion) 10b of the. In this way, by changing the infiltration rate of copper from the front surface side to the back surface side (along the thickness direction or the axial direction) of the vibrating body, the low-order vibration damping effect in the protruding portion is increased, It is possible to prevent occurrence of low-order resonance on the surface of the vibrating body due to stick-slip of the moving body, and thereby effectively prevent "squealing" of the motor.

When actually manufacturing the vibrating body 10, as shown in FIG. 4, the infiltration rate of copper to the protruding portion 10a of the vibrating body 10 and the infiltration rate of copper to the base of the vibrating body 10 are as shown in FIG. Can not be clearly divided on a certain specific surface, and as shown in FIG. 5, the copper infiltration rate is high at the root of the protrusion 10a, and the copper infiltration rate increases toward the tip of the protrusion 10a. Although copper infiltration is performed so as to be low, the vibration damping rate at the protruding portion 10a is still large, so that the "squealing" prevention effect does not decrease.

Further, since the porosity at the tip of the protrusion is larger than the porosity at the root of the protrusion, "squeaking" occurs.
Although it also has a preventive effect, the (bending rigidity / mass) ratio of the protrusion can be made large, and the resonance frequency of the protrusion can be increased. Therefore, it is possible to further elongate the protruding portion 10a and increase the number of the protruding portions to improve the motor performance.

[0043]

As described above, according to the present invention, a vibrating body made of a sintered alloy is infiltrated with a low damping material such as copper in an amount of 0 to 80% of pores of the vibrating body. To provide an improved oscillatory wave motor with less risk of "squealing". Further, according to the present invention, it is possible to realize a vibration wave motor suitable for mass production, which can be produced at a lower cost than the conventional vibration wave motor.

[Brief description of drawings]

FIG. 1 is a graph showing a comparison between the “squealing” start speed of a vibration wave motor of the present invention and the “squeaking” start speed of a conventional vibration wave motor.

2A and 2B are diagrams showing vibration characteristics of a vibrating body used in the vibration wave motor of the present invention, and diagrams showing vibration characteristics of a vibrating body used in a conventional vibration wave motor. c),
The figure which showed.

FIG. 3A is a characteristic diagram of the vibration wave motor of the present invention.
(B) is a characteristic diagram of a conventional vibration wave motor.

FIG. 4 is a sectional view of a vibrating body showing a copper impregnation distribution in a vibrating body of a vibrating wave motor according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a copper impregnation distribution of the vibrating body according to the second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional example and a vibration wave motor of the present invention.

FIG. 7 is a perspective view of a vibrating body of a vibration wave motor of a conventional example and the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Elastic body 2 ... Piezoelectric element 3 ... Rotor 4 ... Shaft 5 ... Pressure spring 6 ... Vibration insulator 7 ... Support plate 8 ... Bearing 9 ... Stator 10 ... Vibrating body 10a ... Projection part 10b ... Base part

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinji Yamamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A vibrating body configured by mounting an electro-mechanical energy conversion element on an elastic body, and a moving body that is pressed against the vibrating body and moves relatively to the vibrating body. In the vibration wave motor according to the present invention, the vibrating body is made of a sintered alloy, and 0 to 80% of a volume ratio of pores of the sintered alloy is filled with a low damping material. Wave motor. 2. The vibrating body has a plurality of comb-teeth-shaped protrusions on the surface side that is pressed against the moving body, and the porosity of the protrusions is higher than the porosity of portions other than the protrusions. The vibration wave motor according to claim 1, wherein the vibration wave motor is also large.