JPH074073B2 - Ultrasonic motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor that utilizes ultrasonic vibration caused by a piezoelectric material.

2. Description of the Related Art Generally, an ultrasonic motor has a structure in which a vibrating body to which a piezoelectric body is fixed and a moving body are in pressure contact with each other, and an electric input to the piezoelectric body causes the piezoelectric body and the vibrating body to have a structure as shown in FIG. This is a principle in which a traveling wave of ultrasonic vibration is generated and the moving body is driven by the frictional force between the vibrating body and the moving body to obtain mechanical energy. In FIG. 4, reference numeral 1 is a piezoelectric body, and the vibrating body 2 is adhered and fixed to the surface thereof. 3 is a moving body, and the friction material 4 is adhered and fixed to the surface thereof. When an electric input is applied to the piezoelectric body 1, a traveling wave of ultrasonic vibration in the A direction is generated in the vibrating body 2. Normally, the amplitude of this traveling wave is 1
It is about 10 μm. Each mass point of the vibrating body makes an elliptic motion like B, and each wave front has a property of moving laterally in the direction opposite to the direction of the traveling wave. The valley portion of the traveling wave has the property of moving laterally in the same direction as the traveling wave. Therefore, the moving body placed on the surface of the vibrating body contacts only the upper part of the wave front and is driven laterally in the C direction by the frictional force with the vibrating body.

In such an ultrasonic motor, metals such as iron and stainless have been proposed as materials for the vibrating body and the moving body.
The vibrating body and the moving body are in pressure contact, and in order to obtain a larger motor mechanical output, a method of increasing the pressing force and a method of increasing the friction coefficient between the vibrating body and the moving body have been proposed. ing.

In order to reduce wear on the contact friction surface between the vibrating body and the moving body to obtain stable mechanical energy for a long period of time and to obtain a larger frictional force, it is proposed to install a friction material fixedly on the contact surface of the moving body. Various materials have been studied, and friction materials made of rubber or engineering plastic materials have been proposed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, when a friction material made of synthetic resin such as rubber or engineering plastic is used, abrasion of the friction material increases, resulting in generation of abrasion powder or output of the ultrasonic motor. There is a problem that the performance changes.

In view of these problems, an object of the present invention is to provide an ultrasonic motor in which the friction material is less worn and the output performance is less likely to change with time.

Means for Solving the Problems In order to achieve the above object, the present invention contains a friction material or a filler made of a liquid crystal polymer in at least the contact surface of the moving body of the surfaces facing each other of the vibrating body and the moving body. A friction material formed by bonding with a liquid crystal polymer is provided.

Action According to the above configuration, the wear of the friction material is small, the wear resistance of the friction material is improved, and as a result, the generation of abrasion powder is reduced, and the change in the output performance of the motor over time is reduced. is there.

Example One configuration example of the main part of the ultrasonic motor of the present invention, that is,
An example of each laminated structure of the vibrating part and the moving part and an arrangement relationship is as shown in FIG. The vibrating section is formed by adhering and fixing the vibrating body 2 made of an elastic body such as metal to the surface of the piezoelectric body 1. The moving part includes a liquid crystal polymer or a friction adjusting filler on the contact surface of the metallic moving body 3 and is bonded with the liquid crystal polymer to bond and fix the friction material 4. The surface of the friction material 4 and the surface of the vibrating body 2 are fixed to each other. It is a structure in which they are brought into pressure contact. By applying a high frequency electric field having a resonance frequency to the piezoelectric body 1, a traveling wave of ultrasonic vibration as described above is generated in the piezoelectric body 1 and the vibrating body 2. At this time, the friction material 4 in contact with the traveling wave head of the vibrating body 2 is integrated with the moving body 3 and is driven by the frictional force with the vibrating body. When no power is input, a holding torque corresponding to the product of the pressing force and the friction coefficient acting between the vibrating body 2 and the friction material 4 is generated.

Here, the friction material 4 is at least a liquid crystal polymer or
Since it is composed of a friction material containing a filler and bonded with a liquid crystal polymer, the friction material has good wear resistance, and as a result, the generation of abrasion powder is not small, and the output performance of the ultrasonic motor changes. Has the effect of decreasing.

The material of the liquid crystal polymer is not particularly limited, but liquid crystal polyester, liquid crystal polyamide, liquid crystal polyamide imide, liquid crystal polyimide or the like can be used. Further, as the filler, in order to adjust the friction performance, powders or fibers of carbon, molybdenum sulfide, fluorine resin, ceramics, inorganic materials such as inorganic oxides and organic materials, and metals can be used. The liquid crystal polymer is
It is a polymer with a structure intermediate between a crystalline state in which molecules are regularly arranged in three dimensions and an amorphous liquid state in which the molecules are randomly present.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

A disc type ultrasonic motor having a diameter of 50 mm and a thickness of 8 mm as shown in FIG. 2 was constructed. In FIG. 2, the vibrating portion of the ultrasonic motor comprises a disc type piezoelectric body 1 on which electrodes are arranged, and a vibrating body 2 made of stainless steel and having substantially the same diameter is adhered and fixed to the surface thereof. A protrusion 2a having a notch in the circumferential direction is provided at a position where the vibration displacement on the surface of the vibrating body 2 is maximized.
The protrusion 2a having a notch is provided to facilitate mechanical vibration of the vibrating portion. The disk-shaped stainless steel moving body 3 constituting the corresponding moving portion has a thickness of 0.1 to 1 including a liquid crystal polymer or a filler and bonded with the liquid crystal polymer.
A 0 mm friction material 4 is fixedly adhered. Although not shown, the vibrating body 2 and the moving body 3 are pressed against each other by appropriate spring tightening means, and the protrusion 2a of the vibrating body 2 and the friction material 4 are in contact with each other.

As the friction material, A to D manufactured as shown below
And the conventional comparative friction material E were used.

Friction material A: Liquid crystal polymer with chemical structure of liquid crystal polyester (Sumitomo Chemical Co., Ltd. product name Econol) is molded and the thickness is
A 1 mm sheet-shaped molded product was obtained.

Friction material B: A mixture of carbon fiber, graphite powder, and liquid crystal polymer polyester (50 parts by weight, manufactured by Unitika Ltd., product name Rod Run) was molded to obtain a sheet-shaped molded product having a thickness of 0.5 mm.

Friction material C: Liquid crystal polyester containing glass fiber (60 parts by weight, product name Vectra manufactured by Polyplastics Co., Ltd.) was molded to obtain a plate-shaped friction material having a thickness of 3 mm.

Friction material D: Liquid crystal polymer containing polytetrafluoroethylene (70 parts by weight, product name Econol manufactured by Sumitomo Chemical Co., Ltd.) was molded to obtain a plate-shaped molded product having a thickness of 5 mm.

Comparative friction material E: glass fiber and phenol resin (50 parts by weight)
Was molded to obtain a sheet-like friction material having a thickness of 1 mm.

An ultrasonic motor as shown in FIG. 2 is constructed by using each of the above friction materials A to E, and electrodes are arranged so that four traveling waves are excited in the circumferential direction of the disk, and the ultrasonic waves are predetermined. Was set to the pressing force of. The wear depth of the friction material when the motor was driven by applying a 600mA input at a resonance frequency of approximately 70khz, the initial starting torque, no-load rotation speed, and 100-hour drive at no-load rotation speed. Now, the unloaded rotation speed and the starting torque were measured.

The respective measurement results are shown in Table 1.

As is clear from Table 1, in the case of an ultrasonic motor that comprises a friction material containing a liquid crystal polymer or a filler and bonded with the liquid crystal polymer (friction material numbers A to D), the friction material after driving for 100 hours The wear depth is 10 μm or less,
In addition, the output performance of the motor, such as no-load rotation speed and starting torque, is not significantly deteriorated.

On the other hand, in the case of the friction material containing no liquid crystal polymer (friction material number E), the wear amount is large, and the no-load rotation speed and the starting torque are largely deteriorated.

FIG. 3 shows a circular ring type ultrasonic motor having another shape according to the embodiment of the present invention. In FIG. 3, the vibrating portion is obtained by adhering and fixing the back surface of the iron vibrating body 2 having a large number of notches on the substantially same surface to the surface of the annular piezoelectric body 1 on which the electrodes are arranged. A friction material 4 containing the liquid crystal polymer of A to D or the filler and bonded with the liquid crystal polymer is adhered and fixed to the annular permanent magnet moving body 3 that constitutes the corresponding moving portion.

The vibrating body 2 and the moving body 3 are pressed by the magnetic attraction force of the moving body made of a permanent magnet, and the protrusion of the vibrating body 2 and the friction material 4 are in contact with each other. The moving part is rotated in the circumferential direction by arranging the electrodes so that seven traveling waves are excited in the circumferential direction of the ring and applying an electric field having a resonance frequency of about 70 kHz.

EFFECTS OF THE INVENTION As is clear from the above description, the present invention has the effect of reducing wear of the friction material by forming the friction material containing the liquid crystal polymer or the filler and bonded with the liquid crystal polymer. Further, the present invention provides an ultrasonic motor having excellent reliability such as the effect of suppressing deterioration of mechanical output such as rotation speed and torque with time.

[Brief description of drawings]

FIG. 1 is a cutaway perspective view of essential parts of an ultrasonic motor of the present invention,
2 and 3 are partially cutaway perspective views of an ultrasonic motor showing an embodiment of the present invention, and FIG. 4 is an operation explanatory view showing the principle of a conventional ultrasonic motor. 1 ... Piezoelectric body, 2 ... Vibration body, 2a ... Vibration body protrusion,
3 ... Moving body, 4 ... Friction material.

Claims (2)

[Claims] 1. An ultrasonic motor for driving a moving body by vibrating the vibrating body through pressure contact between a moving body and an ultrasonic vibrating body that generates a traveling wave on its surface. The ultrasonic motor according to claim 1, wherein a friction material made of at least a liquid crystal polymer is provided at a contact portion of the moving body on a surface where the vibrating body and the moving body face each other. 2. An ultrasonic motor for driving a moving body by vibrating the vibrating body through a frictional force between the ultrasonic vibrating body that generates a traveling wave on the surface and the moving body. 3. An ultrasonic motor according to claim 1, wherein a friction material containing a filler and bonded with a liquid crystal polymer is provided at a contact portion of the moving body on a surface where the vibrating body and the moving body face each other.