JP3292991B2 - Ultrasonic motor with improved startability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for rotating a rotor by generating a traveling wave in a stator, and more particularly, to improving a starting material by improving a slider material adhered to a surface of the rotor on the stator side. It is an improvement.

[0002]

2. Description of the Related Art As is well known, an ultrasonic motor generates a traveling wave by bonding a piezoelectric element to a bronze stator and applying a drive signal thereto, thereby rotating a rotor pressed against the stator. Has become. To effectively apply the traveling wave of the stator to the rotor, a friction material is bonded to the rotor so that an appropriate frictional force is generated between the rotor and the stator.

The output characteristics of an ultrasonic motor are often affected by the characteristics of a friction material (slider material) adhered to a stator-side surface of a rotor. For this reason, there has been proposed a friction material which is provided with a friction material made of plastic containing liquid lubrication, thereby reducing noise during driving of the ultrasonic motor and suppressing deterioration of mechanical output such as torque with time ( JP-A-2-184275). Also, by using a fluororesin as a base material and a thermoplastic resin or a thermosetting resin-filled composite resin as a friction material (slider material), the frictional force is stabilized, the output performance is stabilized, and high performance is achieved. An output version has also been proposed (JP-A-2-285974).

[0004]

In conventional ultrasonic motors, various types of improved slider materials have been proposed, but the rotor is frictionally slid in a state where the rotor is pressed against the stator. There is a problem that metal ions are likely to be generated, thereby causing rust and the like and starting performance is reduced. Therefore, an object of the present invention is to improve the slider material of an ultrasonic motor so that even if moisture is present, metal ions are not generated from the stator, and the startability is improved.

[0005]

According to the present invention, a piezoelectric element is adhered to one surface of a stator to enable generation of a traveling wave,
The above object has been achieved by an ultrasonic motor in which a rotor is rotated by a traveling wave by pressing a rotor against another surface of a stator. Therefore, a slider material is bonded to the rotor surface in contact with the stator, and at least 0.2 wt% of a starting property improving material such as a triazole compound or a diamine compound is added to the slider material. Instead of adding the starting property improving material to the slider material, a starting property improving material such as a triazole-based compound or a diamine-based compound is applied to the surface of the slider material.

[0006]

In the above ultrasonic motor, the starting material such as a triazole compound or a diamine compound is added or applied to the slider material adhered to the rotor.
Even when the slider member is in pressure contact with the stator and slides frictionally, metal ions are less likely to be generated from the stator, and good startability can be maintained. This means that metal ions are generated between the slider material and the stator at high temperature and high humidity. However, the metal ions are chemically changed into a metal complex by the starting characteristic improving material, so that rust does not easily occur and the starting performance is reduced. It is thought that there is no.

[0007]

FIG. 1 shows an embodiment of the present invention. In the ultrasonic motor, a piezoelectric element 2 is adhered to one surface of a disk-shaped stator 1 and divided into two parts, as is well known, and a drive signal having a phase difference of 90 degrees is applied to each of the two. A traveling wave is generated. A rotor 3 is superimposed on the other surface of the stator 1 and pressed against the stator 1 by a spring material 4 so that the rotor 3 is rotated by the action of the traveling wave of the stator 1. Spring material 4
Is fixed to the flange 5a of the output shaft 5, and the output shaft 5 rotates integrally with the rotation of the rotor 3 via the spring member 4 and the flange 5a. A slider member 6 is adhered to the rotor surface in contact with the stator 1, so that the traveling wave generated in the stator 1 effectively acts on the rotor 3.

The slider material 6 is made of a material obtained by adding at least 0.2 wt% of a starting characteristic improving material to a fluorine resin as a base material. As the starting characteristic improving material, a triazole compound, a diamine compound, or the like is used. Instead of adding the starting characteristic improving material to the base material, the starting characteristic improving material may be applied to the surface of the slider material 6 made of fluororesin. In that case, slider material 6
The starting characteristic improving material is rubbed into minute concave portions on the surface of the substrate.

When the effect of the addition amount of the starting characteristic improving material on the slider material 6 on the starting characteristic was measured, the starting failure rate as shown in FIG. 2 was obtained. The stator used for the measurement was made of phosphor bronze, the rotor was made of aluminum,
The base material of the slider material was a fluororesin, and the ultrasonic motor was stopped, and immediately after a drive signal was applied, it did not start and was regarded as defective. As measurement conditions, after leaving for 96 hours at 80 ° C. and 95% humidity, characteristics were measured in a state of leaving for 2 hours at room temperature. From FIG. 2, it can be seen that the defect rate becomes about 0.5% or less when the starting property improving material is 0.2% by weight or more. However, even if it is added in an amount of 5 wt% or more, the defective rate does not change so much. For comparison, the defect rate of the same ultrasonic motor as described above, which was prepared without adding the starting characteristic improving material to the slider material, was measured.
-20%.

As described above, instead of adding the starting characteristic improving material to the base material of the slider material, an ultrasonic motor in which the starting characteristic improving material is applied to the surface of the slider material is prepared. The startup characteristics were measured, and the failure rate of the startup was about 0.3%. In the present invention, the stator 1
The material of the rotor 3 and the base material of the slider material 6 are not limited to the above materials.

[0011]

According to the present invention, since the starting material improving material is added or applied to the slider material bonded to the rotor, the slider material frictionally slides against the stator in a press-contact state and has a high temperature. Even if placed in a wet state, metal ions are hardly generated, and starting failure is hardly caused.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an ultrasonic motor having improved starting characteristics according to the present invention.

FIG. 2 is a diagram showing the relationship between the addition amount of a starting characteristic improving material of an ultrasonic motor and a defective rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 3 Rotor 6 Slider material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-17873 (JP, A) JP-A-2-285974 (JP, A) JP-A-2-97282 (JP, A) JP-A-3-3 215574 (JP, A) JP-A-2-228395 (JP, A) JP-A-2-228394 (JP, A) JP-A-2-68809 (JP, A) JP-A-2-13278 (JP, A) JP-A-63-140674 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02N 2/00-2/16

Claims (2)

(57) [Claims] 1. An ultrasonic motor in which a piezoelectric element is adhered to one surface of a stator to generate a traveling wave, and a rotor is pressed against another surface of the stator to rotate the rotor by the traveling wave. A slider material is adhered to a rotor surface in contact with a stator, and 0.2 to 5% by weight of a triazole-based compound or a diamine-based compound is added to 100% by weight of the slider material. Sound wave motor. 2. An ultrasonic motor in which a piezoelectric element is adhered to one surface of a stator to generate a traveling wave, and the rotor is pressed against another surface of the stator to rotate the rotor by the traveling wave. Wherein a slider material is adhered to a rotor surface in contact with a stator, and a surface of the slider material is coated with a triazole-based compound or a diamine-based compound in an amount of 0.2 to 5 wt% based on 100 wt% of the slider material. Ultrasonic motor with improved start-up performance.