JPH08317668A - Rotating driving gear - Google Patents

Abstract

PURPOSE: To obtain a rotating driving gear by which a spring can be converted into a turning force with good efficiency by a method wherein the spring one end of which has been fixed so as to come into internal contact or external contact with the internal face or the external face of a component is arranged and installed and a vibrator which gives a vibration to the spring is attached. CONSTITUTION: A vibrator 1 such as an ultrasonic vibrator, an electromagnetic vibrator or the like which is composed of a piezoelectric element is attached to a part of a spring 2, one end of the spring is fixed by a fixation member 4, and a cylindrical moving body 3 which comes into external contact with the spring is installed. That is to say, when a vibration is given to the vibrator 1 so as to compress and expand the spring up and down, a force (a) in a relaxation direction and a force (b) in which the spring is lengthened in a line direction are generated, e.g. at a contact in the relaxation direction (actually, the spring comes into contact on the whole outer circumferential face). A resultant force (c) becomes a driving force which turns the cylindrical moving body which comes into external contact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a rotary drive device,
In particular, the present invention relates to a rotary drive device that produces a rotational force based on a change in diameter during expansion and contraction due to vibration of an inscribed or circumscribed spiral spring.

[0002]

2. Description of the Related Art Conventionally, a technique relating to a driving device for driving a rotating body using a piezoelectric element has been developed as an ultrasonic actuator. In this method, a so-called anisotropic material, in which the maximum direction of the longitudinal elastic coefficient always has a constant inclination angle, is used for the driving body, and the vibration of the driving body is used as the driving force for generating the driving force. That is, as a vibrating body, an AC voltage is applied to the piezoelectric element to cause it to vibrate and resonate the driving body. On the other hand, the driving body is configured to generate a rotational torque that is a combination of longitudinal vibration and torsional vibration, independently of the vibration of the piezoelectric element. However, in the conventional case, there is a limitation in the control in forward and backward movements, and the function as an actuator has not been sufficiently exerted at present.

A known technique in this field is, for example, Japanese Patent Laid-Open No. 2-164284. This publication describes an ultrasonic actuator that generates a driving force by using the vibration of a driver element made of an anisotropic elastic material (the direction of maximum longitudinal elastic modulus is given at a constant inclination angle with respect to the axial direction). Is disclosed. An AC voltage is applied to the piezoelectric element bonded to the driver element, and the driver element resonates with the vibration generated in the piezoelectric element, and the driving force is generated by utilizing the coupling between the longitudinal vibration and the sliding vibration. The driving force is transmitted to the rotor and the like by friction. In this known technique, a uniaxially anisotropic material having a constant angle is used, and the rotation angle is limited because it is composed of a fixed portion fixed to the rotation driving member.

In addition to the above, various types of ultrasonic actuators have been considered, but it is desired to develop a driving device that is simpler, more accurate, and easier to use.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to investigate a method of generating a rotational force from a change in spring diameter that occurs when a spring expands and contracts, and to efficiently convert the vibration energy of a vibrator such as a piezoelectric element into a rotational force. A simple rotation drive device that can be converted is provided. Another object of the present invention is to provide a rotary drive device which is light in weight by examining the spring material and the shape of parts and by optimizing the material such as the material and the position of the spring fixing portion.

[0006]

SUMMARY OF THE INVENTION The above-mentioned object is a rotary drive for rotating a component having a cylindrical inner surface or outer surface about its axis, wherein the inner or outer surface of the component is inscribed or circumscribed. Is provided with a spring whose one end is fixed, and a vibrator such as a piezoelectric element for applying vibration is attached to the spring. The vibration frequency of the vibrator is also achieved by a rotary drive device that satisfies a resonance condition with respect to the natural frequency of the spring. Further, the spring is also achieved by a rotary drive device having one end fixed such that at least half or more of the spring is inscribed or circumscribed.

[0007]

According to the present invention, the inner or outer contacting component is rotated by the change in the spring diameter caused by the expansion and contraction of the spring.
For example, when a spring is arranged so as to be circumscribed on the outside of a cylindrical object, when an AC voltage is applied to a vibrator made of a piezoelectric element, the spring expands and contracts as the vibrator vibrates. At the time of expansion, the spring has a smaller diameter and expands while tightening the cylindrical object. Therefore, lateral and upward forces act on the spring, and as a result, a rotational force of the cylindrical object is generated. When shrinking,
On the contrary, the spring diameter becomes thicker and the restraint of the cylindrical object is released, so that no rotational force is generated. As a result, a unidirectional rotational force is generated in the columnar object.

Since the expansion and contraction of the spring is utilized, the rotary drive device of the present invention has a simple structure and can be made lightweight. Hereinafter, the present invention will be further described with reference to the accompanying drawings of the embodiments.

[0009]

【Example】

Embodiment 1 In the present invention, by utilizing the expansion and contraction of a spring, a force generated by expansion and contraction in the spring line direction is exerted outside the expansion and contraction direction of the spring at the contact point of the inner columnar object inscribed or circumscribed. It is used to rotate a cylindrical object.

Further, the rotational force of the present invention is a resultant force of the linear force and the force in the expansion and contraction direction of the spring, and enables the cylindrical object to move in the expansion and contraction direction. FIG. 1 shows the basic configuration of this embodiment. In this figure, a vibrator 1 such as an ultrasonic vibrator or an electromagnet vibrator made of a piezoelectric element is attached to a part of a spring 2, one end of the spring is fixed by a fixing member 4, and a cylindrical moving body circumscribing the spring. 3 is installed. FIG. 2 shows the stress state of the spring surface in the state of FIG.

In these figures, vibration is applied to the vibrator 1,
When the spring is made to expand and contract in the vertical direction, for example, at the contact point in the contracting direction (actually, the entire outer circumference of the spring is in contact), a contracting force a and a spring extending force b are generated. There is c as the resultant force, and this becomes the driving force for rotating the circumscribing cylindrical moving body. In addition,
The shape of the spring of the present invention is not particularly limited and may be circular or polygonal. Also, the spring characteristics are not particularly limited.

However, the vibration characteristic of the vibrator must correspond to this spring characteristic. The spring characteristic conditions will be shown below for the case of a circular coil spring.
First, a spring constant, which is a typical characteristic, is represented by a spring constant k = P / δ (where P: load, δ: corresponding deflection). It is necessary for the vibration characteristics of the vibrator to have a resonance condition suitable for this. As for the allowable load of the spring, it goes without saying that the load ≦ πd ³ σ _a / 32 (where d: spring diameter, σ _a : allowable vertical stress of spring material) is satisfied.

Further, in order to maximize the effect of the present invention, the elastic energy per unit volume of the spring is U = 1/4 (σ _a / 2E) (where E: the longitudinal elastic coefficient of the spring). It is desirable to impart the maximum elastic energy by satisfying the condition. Second Embodiment As a second embodiment, another embodiment of the present invention in which a vibrator is attached to a spring and vibrates as in the first embodiment will be described. FIG. 3 shows a case where the cylindrical moving body has a thin plate shape. In this case, the spring 2 having a few turns or less serves as an effective coil that expands and contracts by the vibration from the vibrator 1 and gives a rotational force. In other words, the rotational force at this time needs to have a contact (contact) with the moving body at least at least half the circumference of the spring, and one fixed end is provided at a position equal to or more than the half circumference of one turn of the spring to provide the rotational force. It occurs.

Another embodiment of the present invention is shown in FIG.
In this figure, unlike the first and third embodiments, the inscribed cylinder is rotated and moved. As shown in FIG. 4, the columnar moving body 3 inscribed in the spring is constituted, and the fixed end portion 4 generates a rotational force from the vibrator 1 side of the columnar moving body 3 via several turns of the spring. That is, the effective coil that expands and contracts by the vibration from the vibrator 1 and imparts a rotational force is made by contact with the spring of several turns. In this embodiment, it is advantageous that the material of the cylindrical moving body and the spring is relatively lightweight, and even if the size thereof is of the order of mm, which is an extremely fine level, a sufficient rotating force can be obtained.

As the material of this embodiment, a fiber filling material is advantageous. In the above embodiments, the oscillator is not limited to the ultrasonic vibration, and the same effect can be obtained even if the oscillator moves up and down in the low frequency range, and the structure shows an example in which the spring is vertical. However, for example, it may be placed horizontally or have an angle. Further, when the vibrator of the present embodiment is composed of piezoelectric elements, BaTiO ₃ -CaTiO ₃ system, BaTiO ₃ -PbTiO
_{The 3} system and the PbTiO ₃ —PbZrO ₃ system are preferred. Further, the fiber reinforced material used as the rotating body is a fiber reinforced plastic made by filling glass fiber, carbon fiber, boron fiber, high-strength whisker material, etc. into polyester, epoxy resin, phenol resin, silicone or other resin as long fiber. Is preferred.

[0016]

According to the present invention, a vibrator is attached to a spring whose one end is fixed, and the rotational force acting on the spring is transmitted by effectively contacting the inner surface or the outer surface of the moving body to enable rotational driving. . Further, the present invention has a large degree of freedom in the shape of the rotating body, and is capable of constructing a small rotating body such as a cylindrical body to a thin plate-like body, and a very fine level.
Furthermore, since the mechanism is simple, the weight can be reduced. For example, it can be applied to an automatic direction adjusting mechanism for an air conditioner outlet, a remote control mirror, etc. for use in automobiles, and can form a low-cost rotation and movement mechanism with a relatively simple structure.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a rotary drive device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a stress state at a contact point between a spring and a rotating body according to the present invention.

FIG. 3 is a diagram showing a basic configuration of a plate-shaped rotation driving device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a basic configuration of an ultrafine rotation drive device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 ... Oscillator 2 ... Spring 3 ... Cylindrical moving body 4 ... Fixed member 5 ... Contact point with cylindrical moving body

Claims (3)

[Claims] 1. A component having a cylindrical inner surface or an outer surface,
A rotation driving device that rotates about its axis, wherein a spring having one end fixed so as to be inscribed or circumscribed on the inner surface or the outer surface of the component, such as a piezoelectric element for imparting vibration to the spring. A rotary drive device having a vibrator attached. 2. The rotation drive device according to claim 1, wherein the vibration frequency of the vibrator satisfies a resonance condition with respect to the natural frequency of the spring. 3. The rotary drive device according to claim 1, wherein one end of the spring is fixed such that at least half or more of the spring is inscribed or circumscribed.