JPH089444Y2 - Radial hydrodynamic bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a radial dynamic pressure fluid bearing, and is applicable to, for example, a rotary polygon mirror device in an optical scanning device or the like.

(Prior Art) For example, in a rotary polygon mirror device in an optical scanning device or the like, a radial dynamic pressure fluid bearing is used to rotatably support a polygon mirror. This radial dynamic pressure fluid bearing has a rotating member that rotates by interposing a fluid between it and a supporting member, and any one of a receiving surface of the supporting member and a receiving surface of the rotating member facing the receiving surface of the supporting member. A plurality of grooves for generating dynamic pressure are engraved on the receiving surface, and fluid is caused to flow through the groove portions as the rotating member rotates, so that dynamic pressure is generated in the groove portions to support the rotating member. ing.

FIG. 5 shows an example of a conventional radial dynamic pressure fluid bearing. In FIG. 5, a cylindrical rotating member 2 is rotatably fitted on the inner peripheral side of a cylindrical supporting member 1. Support member 1
The inner peripheral surface of the rotary member 2 and the outer peripheral surface of the rotary member 2 respectively form receiving surfaces, and these receiving surfaces face each other with a predetermined gap. A plurality of grooves 3 for generating dynamic pressure are formed on the outer peripheral surface of the rotating member 2. The groove 3 is formed so as to be inclined at a predetermined angle with respect to the axial direction and symmetrical with respect to the center in the bearing width direction. Air or other fluid is interposed between the receiving surface of the supporting member 1 and the receiving surface of the rotating member 2, and when the rotating member 2 rotates, the fluid flows through the groove 3 as shown by an arrow in the bearing width. The fluid flows from both ends in the direction toward the center in the bearing width direction, and a dynamic pressure is generated in the groove portion 3 by the flow of the fluid, and the rotary member 2 is supported by the dynamic pressure.

(Problems to be solved by the invention) According to the conventional radial dynamic pressure fluid bearing as described above, since the fluid flows from both end sides in the bearing width direction toward the center side in the bearing width direction, it is generated in the groove 3 portion. The dynamic pressure distribution
As shown by the diagram on the right side of FIG. 5 or the broken line b of FIG. 4, it is large at the central portion in the bearing width direction and small at both ends in the bearing width direction. Therefore, this is substantially the same as the case where the rotary member 2 is supported along a single line that goes around the center portion in the bearing width direction, and there is a problem that the rotary member 2 tends to fall down when subjected to a disturbance. In order to solve such a problem, generally, the ratio of the shaft diameter to the bearing length (L / D) of the radial dynamic pressure fluid bearing is set to about 1, and the bearing portions are formed at two locations in the axial direction. ing. However, this increases the height of the radial hydrodynamic bearing. Further, in the case of a flat bearing in which the ratio of the shaft diameter to the bearing length is small, the bearing portion is formed in one place to accept the above-described inclination with respect to the disturbance.

The present invention has been made in order to solve the above-mentioned conventional problems, and provides a radial dynamic pressure fluid bearing in which the rotating member is not tilted due to disturbance even if the bearing portion is provided at one place. To aim.

(Means for Solving the Problems) In the present invention, a groove for generating a dynamic pressure is axially tilted at a predetermined angle with respect to the axial direction of a receiving surface and is symmetrical about an axial center. The direction of the inclination from the center of the is reversed, and the fluid is directed toward both sides in the axial direction. (B) It is formed in the same direction with respect to the circumferential direction and at almost equal intervals, and (c) the end is supported. The receiving surface remains between the end portion and the end portion of the supporting member or the rotating member without reaching the end portion of the member or the rotating member, and (d) the depth is made uniform.
Is formed so as to satisfy the above condition, and fluid is caused to flow from the center in the bearing width direction to both ends in the axial direction along with the rotation of the rotating member to generate dynamic pressure in the groove portion to support the rotating member. To do.

(Operation) When the rotating member rotates, the fluid interposed between the rotating member and the supporting member flows from the center in the bearing width direction toward the axially both ends through the groove for generating dynamic pressure, and the bearing width of the groove portion. A large dynamic pressure is generated at both ends in the direction, which is substantially the same as when the rotating member is supported at two axial positions.

(Example) An example of a radial dynamic pressure fluid bearing according to the present invention will be described below with reference to the drawings.

In FIG. 1, which shows an example in which the radial dynamic pressure fluid bearing according to the present invention is applied to a rotary polygon mirror device, reference numeral 11 is a support member that forms a cylindrical fixed bearing portion. A cylindrical rotating member 12 is rotatably fitted in a prone shape. The inner peripheral surface of the support member 11 and the outer peripheral surface of the rotating member 12 each form a flat receiving surface, and these receiving surfaces face each other with a predetermined gap. The outer peripheral surface 29 of the rotating member 12, which is one of the two receiving surfaces.
As shown in FIG. 2, a plurality of grooves 28 for generating dynamic pressure are formed in the same direction in the circumferential direction at substantially equal intervals and with a substantially uniform depth. These grooves 28 are inclined in a predetermined angle with respect to the axial direction and symmetrically with respect to the center in the bearing width direction. Is formed so as to guide the fluid to both sides in the axial direction, and
28 is the circumferential groove at the bent portion at the center of the above-mentioned “K” shape.
It communicates with 26. Further, each groove 28 is arranged so that each end thereof does not reach the end of the rotating member 12, and therefore, the circumference of the rotating member 12 is provided between each end of each groove 28 and the rotating member 12. The surface 29 is formed so as to remain as a receiving surface. On the other hand, a peripheral groove 24 is formed on the inner peripheral surface side of the support member 11 at a position facing the peripheral groove 26. Air or other fluid is interposed between the inner peripheral surface of the support member 11 and the outer peripheral surface of the rotary member 12, and the support member 11 has a supply hole for supplying the fluid between the support member 11 and the rotary member 12. 22 are formed. This supply hole
Reference numeral 22 connects the outside of the support member 11 and the circumferential groove 22.

A radial dynamic pressure fluid bearing is formed between the support member 11 and the rotating member 12 with the above-described configuration. Rotating member
The direction of rotation of 12 is such that the fluid flows along each groove 28 from the center in the bearing width direction toward both ends in the axial direction as shown by the arrow in FIG. 2 when the rotating member 12 rotates. Become. Therefore, when the inclination of each groove 28 with respect to the axial direction is reversed, the rotation direction of the rotating member 12 is reversed. In this way, the rotation of the rotating member 12 causes the fluid to flow from the center in the bearing width direction toward both ends in the axial direction, whereby dynamic pressure is generated in the grooves 28, and the rotating member 12 is supported. When the fluid flows from the center of the bearing width direction to both ends in the axial direction, the supply hole 22 and the circumferential groove 24
And the fluid is supplied through the circumferential groove 26. Then, the groove 28 is interrupted at both ends in the axial direction, and the fluid passage is formed in the rotating member 12.
By being narrowed by the outer peripheral surface 29, a large dynamic pressure is generated at both axial end portions. A solid line a in FIG. 4 shows such a dynamic pressure distribution, and a large dynamic pressure is generated in the regions Ea and Eb at both ends in the axial direction, and the rotating member 12 is supported at two positions in the axial direction. It turns out that it is substantially the same as. The broken line b in FIG. 4 shows the dynamic pressure distribution in the conventional bearing shown in FIG.

In FIG. 1, a cylindrical yoke 17 is fixed to the inner peripheral surface of the rotating member 12, and a cylindrical rotor magnet 18 is fixedly fitted to the inner peripheral surface of the yoke 17. Support member 11
A circuit board 21 is fixed to the inner circumferential side of the bottom of the, and a support column 20 fixed to the center of the circuit board 21 stands up in the rotor magnet 18. A drive coil 19 having an appropriate number of phases is wound around the support 20. A magnetic sensor for detecting the rotational position of the rotor and switching the energization to the drive coil 19 is attached to the circuit board 21, and a predetermined wiring pattern is formed. A drive motor is constituted by such members, and the rotary member 12 is rotationally driven by the drive motor. A boss 16 is provided at the center of the upper end surface of the rotating member 12 so as to project.
The polygonal mirror body 13 is placed on the upper end surface of the and the polygonal mirror body 13 is fitted into the boss 16 so that the polygonal mirror body 13 is rotated.
It is stuck to. Therefore, the polygon mirror 13 is rotationally driven by the drive of the drive motor.

The circumferential groove 24 on the support member 11 side and the circumferential groove 26 on the rotating member 12 side
Either one of them may be omitted.

As described above, according to the above-described embodiment, the fluid is supplied from the center portion in the bearing width direction along with the rotation of the rotating member 12 to cause the fluid to flow along the grooves 28 toward both ends in the axial direction, and the axial direction of each groove 28. Each groove 28 without reaching both ends to the end of the rotating member 12
Between the end of the rotating member 12 and the end of the rotating member 12.
Since the dynamic pressure is generated on both ends in the axial direction while leaving it as the receiving surface, the rotating member 12 is formed at two positions in the axial direction.
Is substantially the same as that supported, and even with a flat bearing with a small ratio of the axial length to the shaft diameter (L / D), there is little tilt of the rotating member 12 due to disturbance and stability. It is possible to obtain a radial dynamic pressure fluid bearing.

Note that, as shown in FIG. 3, the V-shaped groove formed on the receiving surface of the rotating member 12 does not necessarily need to be communicated with the peripheral groove 26 as shown in FIG. In FIG. 3, reference numeral 30 indicates
It is a plurality of grooves formed in a V shape so as to be inclined at a predetermined angle with respect to the axial direction and symmetrical about the center in the bearing width direction. Also in this case, each end of each groove 30 has a rotating member.
The outer peripheral surface 31 of the rotary member 12 is formed between each end of each groove 30 and the end of the rotary member 12 so as not to reach the end of the rotary member 12. Then, as the rotating member 12 rotates, the fluid flows along the grooves 30 from the center of the bearing width direction toward both ends in the axial direction, so that a large dynamic pressure is generated at both ends in the axial direction. It has become.

In each of the embodiments described above, the groove for generating the dynamic pressure is formed in the rotating member.
Although it is provided on the 12 side, this groove may be provided on the support member 11 side. Further, the radial dynamic pressure bearing according to the present invention is also applicable to the type in which the rotary member rotates on the outer peripheral side of the support member. Further, the radial dynamic pressure fluid bearing according to the present invention can be widely applied to other than the rotary polygon mirror device.

(Effects of the Invention) According to the present invention, as the rotating member rotates, the fluid is supplied from the center portion in the bearing width direction to cause the fluid to flow along the grooves for generating the dynamic pressure to the both axial ends, and the both axial ends. Since the dynamic pressure is generated on the side, it is substantially the same as the rotating member being supported at two locations in the axial direction, and even with a flat bearing having a small ratio of the axial length to the shaft diameter. Even so,
It is possible to obtain a radial dynamic pressure fluid bearing in which the rotating member is less inclined due to disturbance. Further, since the grooves are formed symmetrically with respect to the axial center and at substantially equal intervals in the same direction in the circumferential direction, there is no unevenness of fluid pressure in the circumferential direction, and the rotating member is stably supported. You can further,
The receiving surface is left between the both ends of each groove and the end of the supporting member or the rotating member without reaching both ends of the groove to the end of the supporting member or the rotating member, and the depth of each groove Since the pressure is made uniform, the fluid pressure sharply rises at both ends in the axial direction, the rotating member can be reliably supported at the two positions at both ends in the axial direction, and the rotation of the rotating member can be stabilized.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an application example of a radial dynamic pressure fluid bearing according to the present invention, and FIG. 2 is a partial sectional front view showing an embodiment of a radial dynamic pressure fluid bearing according to the present invention. Is a partial sectional front view showing another embodiment of the radial dynamic pressure fluid bearing according to the present invention, and FIG. 4 is an example of dynamic pressure distribution obtained by the radial dynamic pressure fluid bearing according to the present invention. FIG. 5 is a partial cross-sectional front view showing an example of a conventional dynamic pressure bearing, which is shown in comparison with the dynamic pressure distribution in a fluid bearing. 11 ... Support member, 12 ... Rotating member, 28, 30, 34 ... Grooves for generating dynamic pressure.

Claims (1)

[Scope of utility model registration request] 1. A rotating member that rotates by interposing a fluid between the supporting member and the supporting member, wherein any one of the receiving surface of the supporting member and the receiving surface of the rotating member facing the supporting surface of the rotating member. In a radial dynamic fluid bearing having a plurality of grooves for generating dynamic pressure, each groove is (a) inclined at a predetermined angle with respect to the axial direction of the receiving surface and symmetrical with respect to the center of the axial direction. As described above, the direction of inclination from the center in the axial direction is opposite, and the fluid is formed so as to guide the fluid toward both sides in the axial direction. (C) The end does not reach the end of the supporting member or the rotating member, and the receiving surface remains between the end and the end of the supporting member or the rotating member. The condition that the depth is uniform is satisfied. Accordingly, a fluid is caused to flow from the center in the bearing width direction to both ends in the axial direction to generate a dynamic pressure in the groove portion, thereby supporting the rotating member.