JPH0724955Y2 - Ultrasonic linear motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an ultrasonic linear motor suitable as a drive source for electronic devices and precision machines.

[Prior Art] In electronic devices and precision machines, an actuator that requires a small space for mounting and enables precise positioning accuracy is required.

Therefore, the present applicant first proposed an efficient ultrasonic linear motor that does not need to increase the processing accuracy in the manufacturing process and utilizes the resonance state of the constituent members (Japanese Patent Application No. 63-
No. 60714).

For example, as shown in FIG. 3, the vibrating body 4 is constructed by connecting one ends of parallel prismatic leg portions 1 and 2 with a prismatic body portion 3 to form a vibrating body 4. Piezoelectric elements 6 and 7 for imparting vibration to the leg portions 1 and 2 and the body portion 3 are attached to the mounting surfaces 5 at both corners, and the tip ends of the leg portions 1 and 2 are cylindrical rails 8. Running surface formed on the top
The piezoelectric elements 6 and 7 are ultrasonically vibrated at the same frequency while being abutted on the 8a to vibrate the leg portions 1 and 2 and the body portion 3 so that the tips of the leg portions 1 and 2 are Elliptical vibrations of the same frequency are generated along the longitudinal direction of the body portion 3, so that the vibrating body 4 is linearly moved in one direction along the rails 8.

[Problems to be Solved by the Invention] However, the conventional ultrasonic linear motor described above is
Since the piezoelectric elements 6 and 7 made of ceramics have a characteristic of being inferior in moisture resistance, there is a drawback that the life is unavoidable when used in a high humidity environment or an inferior environment in which dust is often generated.

The present invention has been made under such a background, and an object thereof is to provide a highly versatile ultrasonic linear motor which is excellent in moisture resistance and can be used without any problems even in a bad environment where a lot of dust is generated. And

[Means for Solving the Problems] In order to solve the above problems, the present invention has at least two columnar leg portions whose tips abut against a running surface, and a body portion that connects the base ends of these leg portions. A vibrating body, a mounting surface formed at both ends in the axial direction of the body of the vibrating body inclining with respect to the axial direction of the body, and a direction that is mounted on the mounting surface and intersects the axial direction of the body. A vibrating piezoelectric element, a cover covering the vibrating body is provided around the vibrating body, and a protective material for protecting the piezoelectric element from the external environment is filled in the cover. It is made of a shock-absorbing material, and only the piezoelectric element and the body of the vibrating body are covered with the protective material, and vibration in a direction intersecting the axial direction of the body is divided into components parallel to the axial direction of the body. Divided into vibrations of orthogonal components and transmitted to the legs, the vibrating body The configuration is such that linear movement is performed in the axial direction of the body relative to the traveling surface.

[Operation] According to the above configuration, since the piezoelectric element is covered with the protective material filled in the cover, it is not affected by the external environment. Further, since the piezoelectric element is integrated with the vibrating body by the protective material, the piezoelectric element is prevented from falling off the vibrating body.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, reference numerals 10 and 11 denote leg portions that abut the traveling surface 8a of the rail 8 having a prismatic tip, and 12 denotes a body portion that connects the base ends of these leg portions 10 and 11. The elastic member is made up of a substantially square cross-section of each part and the whole is formed into a substantially U-shape to form the vibrating body 13. These legs 10,
Although the material and dimensions of 11 and the body 12 are appropriately selected, aluminum is used as the material in the example, and the body 12 is 5 mm □ × 2.
6mmL, legs 10 and 11 are 5mm □ × 10mmL. Vibrating body
Other than the above, the material of 13 may be a metal material such as duralumin, brass or stainless steel, an inorganic material such as alumina, glass or silicon carbide, an organic material such as polyimide resin or nylon.

The corner of the vibrating body 13 is 45 ° with respect to the legs 10, 11 and the body 12.
Are chamfered to form an angle, and piezoelectric elements (vibration imparting means) 15 and 16 are attached to the attachment surface 14 using an adhesive or the like. The piezoelectric elements 15 and 16 are made of laminated piezoelectric actuators or single-plate piezoelectric ceramics, and are ultrasonically vibrated in a direction orthogonal to the mounting surface 14 by an alternating voltage applied from a power source (not shown). . The dimensions of the piezoelectric elements 15 and 16 are also appropriately selected in the same manner as the leg portions 10 and 11 and the like, but in the illustrated example, 5 mm □ × 9 mmL was used.

A cover 17 is arranged around the vibrating body 13.
This cover 17 is provided with bent portions 19 extending toward the tip ends of the leg portions 10 and 11 at both ends of a ceiling plate 18 extending along the upper surface of the body portion 12 of the vibrating body 13 and is substantially U-shaped. Forming the cover body 20
On the other hand, a pair of guide plates 21 are formed at both ends of the central portion of the ceiling plate 18 while forming the above.

Here, the width of the cover body 20 is set to be slightly larger than the width of each portion of the vibrating body 13, while the entire length thereof is sufficiently large between the inner surface of each bent portion 19 and the piezoelectric elements 15 and 16. The gap is defined so that the vibrating body 13 and the piezoelectric elements 15 and 16 can be housed therein. On the other hand, the above guide plate
The reference numeral 21 hangs down from both ends of the central portion of the ceiling plate 18 toward the tip ends of the leg portions 10 and 11, and the body portion 12 of the vibrating body 13 is loosely fitted in the gap.

Inside the cover 17, silicone rubber (protective material) 22
Is filled so as to fill the upper portion of the cover 17 in the width direction, whereby the cover 17 and the vibrating body 13 are integrally joined, and the body 12 of the vibrating body 13 and the piezoelectric element 15,
Only 16 is completely covered with silicone rubber 22 so as to be isolated from the external environment. In the figure, reference numeral 23 is
An adjusting screw for adjusting the positional relationship between the cover 17 and the vibrating body 13 in the vertical direction (longitudinal direction of the legs 10, 11).

The ultrasonic linear motor configured as described above is used as a rail 8
To move along the running surface 8a in the longitudinal direction of the
The tip ends of 10 and 11 are erected on the running surface 8a by abutting against the running surface 8a, and in this state, an alternating voltage having the same resonance frequency as the vibrating body 13 but different phase is applied to each piezoelectric element 15, 16. They are applied and ultrasonically vibrated.

Then, the vibrating body 13 moves in the longitudinal direction of the legs 10 and 11 and the body portion 12.
Since it is excited at the resonance frequency in a direction intersecting with any of the longitudinal directions, each leg 10, 11 longitudinally vibrates at the resonance frequency in the direction orthogonal to the running surface 8a, and at the same time, in the direction along the running surface 8a. It flexibly vibrates at the resonance frequency. And each leg 1
The tips of 0 and 11 make an elliptical vibration at the resonance frequency in the same direction due to the combination of the longitudinal vibration and the flexural vibration.

When elliptical vibration occurs at the tips of the legs 10 and 11 in this way, the surface pressure between the tips of the legs 10 and 11 and the running surface 8a of the rail 8 is a vertical component of the ellipse vibration (the legs 10 and 11). 11 component in the longitudinal direction) changes periodically. Also, each leg 1
At the tips of 0 and 11, a force (hereinafter, referred to as a driving force) for kicking the rail 8 in the longitudinal direction is generated by the horizontal component of the elliptical vibration (a component in the longitudinal direction of the rail 8), and this driving force is generated. The direction changes as the phase of the elliptical vibration changes. The driving force increases as the surface pressure acting between the tips of the legs 10 and 11 and the running surface 8a of the rail 8 increases, that is, the legs.
The larger the frictional force acting between the rails 10 and 11 is, the more effective the driving force is. Therefore, the driving force generated at the tips of the legs 10 and 11 acts with different strength depending on the direction of action, resulting in vibration. The body 13 is moved in one direction.

In the above embodiment, the piezoelectric elements 15 and 16 are made of silicone rubber.
Since it is covered with 22, the piezoelectric elements 15 and 16 are not affected even when used in a high-humidity environment or in a bad environment where a lot of dust is generated, and as a result, the life of the piezoelectric elements 15 and 16 is reduced. Greatly improved. Therefore, according to the above-mentioned embodiment, it is possible to provide a versatile ultrasonic linear motor that can be used in any environment. In addition, in the above embodiment, the piezoelectric element 15,
Since the silicone rubber 22 prevents the 16 from falling off from the mounting surface 14, there is no need to pay special attention to its handling, and further, when the cover 17 etc. accidentally collides with the components of the device during use. Silicon rubber 22
Since it is buffered by the piezoelectric elements 15, 16, the piezoelectric elements 15, 16 are more thoroughly protected and the reliability is significantly improved. In this embodiment, silicone rubber is used as a protective material to be filled especially inside the cover 17.
However, the present invention is not limited to this, and a material that does not absorb ultrasonic vibrations of the piezoelectric elements 15 and 16 and the vibrating body 13 and that can isolate the piezoelectric elements 15 and 16 from the external environment. Any shock absorbing material can be used instead, and specifically, various rubbers such as urethane foam rubber and resins can be used.

Further, the shape of the cover 17 shown in the present embodiment is also merely an example, and it can be arbitrarily modified as long as it has a shape capable of being filled with a protective material inside, such as a box shape. Furthermore, in the present embodiment, the vibrating body 13 is formed in a substantially U shape by the two leg portions 10 and 11 and the body portion 12. However, the ultrasonic linear motor of the present invention is not limited to this, and the leg portion is not limited thereto. Naturally, it is also possible to configure the vibrating body by itself, or to make deformation such as to have three or more legs or to bend the body.

Furthermore, the dimensions of each part of the vibrating body 13 and the like illustrated in the present embodiment are merely examples, and these may be arbitrarily designed and changed according to the usage pattern.

[Effects of the Invention] As described above, according to the present invention, since the piezoelectric element is covered with the protective material, the life of the piezoelectric element does not deteriorate even in a high humidity environment or a bad environment in which dust is often generated. The protective material also prevents the piezoelectric element from falling off the vibrating body. Further, in particular, since the protective material is made of a material that absorbs shock and covers only the piezoelectric element and the body of the vibrating body, the shock received when the cover or the like collides is buffered, and the piezoelectric element is protected. It can be fully protected. Since the protective material covers only the piezoelectric element and the body of the vibrating body, it is possible to prevent the driving force of the leg portion of the vibrating body from being attenuated and prevent the driving force from decreasing. Can be maintained. Therefore, according to the present invention, it is possible to provide an ultrasonic linear motor having high versatility and high reliability regardless of use environment.

[Brief description of drawings]

FIGS. 1 and 2 show an embodiment of the present invention. FIG. 1 is a front view, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. It is a front view of a sound wave linear motor. 8 …… Rail, 8a …… Running surface, 10,11 …… Legs, 12 ……
Body, 13 …… Vibrator, 15,16 …… Piezoelectric element, 17 …… Cover, 22 …… Silicon rubber (protective material).

Claims (1)

[Scope of utility model registration request] 1. A vibrating body having at least two columnar legs whose tips abut against a running surface, and a body connecting the base ends of these legs, and both axial ends of the body of the vibrating body. And a piezoelectric element which is mounted on the mounting surface and is oscillated in a direction intersecting the axial direction of the body portion. A cover for covering the vibrating body is provided in the cover, a protective material for protecting the piezoelectric element from the external environment is filled in the cover, and the protective material is made of a material that absorbs shock, and the piezoelectric material is used for the piezoelectric material. Only the element and the body of the vibrating body are covered, and the vibration in the direction intersecting the axial direction of the body is divided into the components parallel to the axial direction of the body and the components orthogonal to each other and transmitted to the legs. , A structure in which the vibrator moves linearly in the axial direction of the body relative to the running surface. Ultrasonic linear motor, which is characterized by