JPH0591691A - Bearing structure for micromachine - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a bearing structure of a micromachine for a micro electrostatic motor and the like, which has a simple structure and can suppress friction to obtain a stable motor output. [Structure] A shaft through hole 5 having a diameter larger than that of a rotary shaft 2 is opened in a bearing base 3, and a thin wire 4 is stretched around projections 6 dispersedly arranged on the periphery of the shaft through hole. A polygonal annular shaft support hole 4a is formed in the center portion, and a circumferential groove 7 formed on the axis of the rotary shaft is fitted into the annular shaft support hole formed by a thin wire to support the shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a micromachine intended for implementation of an ultra-small electrostatic motor having a diameter of 1 mm or less.

[0002]

2. Description of the Related Art Recently, as a motor applied to the field of micro-mechatronics, research and development of a microminiature electrostatic motor utilizing microfabrication technology for IC manufacturing has been under way, and its outline is summarized in, for example, Journal of Japan Electrostatic Society. Volume 14
It is introduced in the special issue “Micro Electrostatic Motor” (Author: Hiroyuki Fujita) in Issue 3 (1990).

On the other hand, various bearings such as rolling bearings, sliding bearings, and air bearings have been conventionally known as bearing structures used in small motors. Attempts have been made to adopt bearings.

[0004]

By the way, one of the problems that must be solved when manufacturing a micro motor having a diameter of about 1 mm is the influence of bearing friction. That is, since the torque generated by the motor is proportional to the area of the electrostatic motor and the volume of the electromagnetic motor, the influence of the frictional force at the bearing portion significantly appears in the output characteristics of the motor as the motor is downsized. .. In this respect, the above-mentioned rolling bearing has an advantage of low frictional resistance, but it is very difficult to manufacture a bearing having a diameter of 1 mm or less. On the other hand, the slide bearing is relatively easy to make small in size, but has a drawback in that sliding friction with the rotating shaft is large. On the other hand, the air bearing has a merit that the influence of friction is small because the rotating shaft is supported in a non-contact manner. However, since the structure requires an air supply device and the like, the use environment of the micro motor is restricted. A bearing utilizing the Meissner effect of superconductivity is also possible in principle, but it is not practical because it requires a large cryostat for implementation.

The present invention has been made in view of the above points, and an object of the present invention is to provide a micromachine for a micro-electrostatic motor or the like, which has a simple structure and can suppress friction to obtain a stable motor output. To provide a bearing structure.

[0006]

In order to solve the above-mentioned problems, the bearing structure of the present invention is such that a shaft through hole having a diameter larger than the diameter of the rotary shaft is opened in the bearing base, and the shaft through hole is formed. A thin wire is wound around the hole area to form a polygonal annular bearing hole, and a circumferential groove formed on the rotary shaft is fitted in the annular bearing hole to support the bearing.

Here, in the above bearing structure, protrusions are provided dispersedly on the periphery of the shaft through hole of the bearing base, and thin wires are bridged between the protrusions to form polygonal annular shaft support holes. can do. Also, the circumferential groove of the rotary shaft is set such that the inner diameter of the groove is larger than the inscribed circle of the polygonal annular shaft support hole, and the groove width and groove depth are larger than the wire diameter of the thin wire. Good

[0008]

With the above construction, when the rotary shaft is supported, the circumferential groove of the rotary shaft and the annular shaft support hole formed by the thin line are engaged with each other by line contact. The contact area between the bearing and the rotary shaft is small, and the frictional force acting between the bearing and the rotary shaft is small. Also, if the rotating shaft tries to be eccentric from the shaft center due to some external force or unbalance of the motor torque, the tension of the thin wire increases on the eccentric side and a force that pushes the rotating shaft back to the center of rotation acts. The shaft always obtains stable rotation.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. Note that the illustrated example is intended for an ultra-small electrostatic motor having a diameter of about 1 mm. In the figure, 1 is a rotor of a micro electrostatic motor, 2 is a rotary shaft, 3 is a bearing base, and 4 is a thin metal wire of a wire diameter of the order of microns, which extends around the bearing base 3 to support the rotary shaft 2. is there. Here, first, the bearing base 3 is provided with a shaft through hole 5 having a diameter larger than the diameter of the rotary shaft 2, and a plurality of projections 6 (see FIG. In the example shown, 7 lines are provided dispersedly. Then, as shown in FIG. 4, the thin wire 4 is continuously bridged between the protrusions 6 from the start end to the end, and a polygonal shape is formed in the center of the hole region of the shaft through hole 5 in the same manner as a single stroke. An annular shaft support hole 4a (regular heptagon in the illustrated example) is formed.

On the other hand, a circumferential groove 7 is formed on the shaft of the rotary shaft 2 at a position facing the annular shaft support hole 4a formed by the thin wire 4. The inner diameter of the circumferential groove 7 is slightly larger than the polygonal inscribed circle of the annular shaft support hole 4a described above, and the groove width and groove depth are set to be larger than the wire diameter of the thin wire 4. Then, the circumferential groove 7 is fitted into the annular shaft support hole 4a of the thin wire 4 to support the rotary shaft 2 as shown in FIGS.

In the shaft support state shown in FIGS. 2 and 3, tension is applied to the thin wire 4 stretched around the bearing base 3, and the rotary shaft 2 is in line contact with the center position of the polygonal annular shaft support hole 4a. At the same time as holding, the rotary shaft 2 is restrained and held also in the thrust direction.
As a result, the rotary shaft 2 is pivotally supported by the fine wire 4 by applying a slight frictional force. Further, when the rotating shaft 2 tries to be eccentric from the rotation center due to motor torque unbalance, external force, etc. during rotation, the tension of the thin wire 4 abutting the eccentric side increases, and the reaction force causes the rotating shaft 2 to rotate. Since it is pushed back to the position, the rotary shaft 2 is always held in a stable position.

[0012]

As described above, according to the bearing structure of the present invention, it is possible to stably and rotatably support the rotating shaft about the rotation center in a substantially line contact state by the thin wire stretched around the bearing base side. The frictional force can be significantly reduced as compared with the conventional plain bearing. Moreover, the bearing can be easily manufactured only by stretching a thin wire around the bearing base, and can be easily applied to a micromachine having a diameter of about 1 mm such as an ultra-small electrostatic motor.

[Brief description of drawings]

FIG. 1 is a configuration perspective view of an embodiment of the present invention.

FIG. 2 is a plan view of a main part in FIG.

FIG. 3 is a vertical cross-sectional view of the main part in FIG.

FIG. 4 is a state diagram of bridging thin wires in FIG.

[Explanation of symbols]

 2 Rotating shaft 3 Bearing base 4 Thin wire 4a Polygonal annular shaft support hole 5 Shaft through hole 6 Protrusion 7 Circumferential groove

Claims (3)

[Claims] 1. A bearing structure for a micromachine intended for an ultra-small electrostatic motor or the like, wherein a shaft through hole having a diameter larger than a diameter of a rotary shaft is opened in the bearing base, and the shaft through hole A thin wire is stretched around the hole area to form a polygonal annular bearing hole in the center thereof, and a circumferential groove formed on the rotating shaft is fitted in the annular bearing hole to support the hole. Micromachine bearing structure. 2. The bearing structure according to claim 1, wherein protrusions are provided dispersedly on the periphery of the shaft through hole of the bearing base, and thin wires are bridged between the protrusions to form polygonal annular shaft support holes. A bearing structure for a micromachine characterized by being formed. 3. The bearing structure according to claim 1, wherein the circumferential groove of the rotary shaft is such that the inner diameter of the groove is slightly larger than the inscribed circle of the polygonal annular shaft support hole, and the groove width and groove depth. A bearing structure for a micromachine, characterized in that the thickness is larger than the diameter of the thin wire.