JPS5989819A - Fluid bearing device - Google Patents

Abstract

PURPOSE:To lengthen the life of a fluid bearing device and to improve the rotation reliability by providing a thrust ring which is minutely deformed by a shock along the thrust and is provided with a thin structure to absorb and moderate such a shock. CONSTITUTION:A thrust ring 9 is provided with a circular groove 21 and with a thin coupling portion 19. The roundness of an appropriate radius of curvature is provided on the forward end of the leg portion 20, so that in spite of minute deformation, the ring is brought into linear contact with a sleeve 10 to reduce frictional resistance to the minimum. When vibration/shock is applied along the thrust, the sleeve 10 is vertically moved to tend to push up the leg portion of the thrust ring 9. The vertical power of the sleeve 10 is, however, absorbed and moderated by spring property of a thin-structure coupling portion of the thrust ring 9. In this case, the leg portion is always brought into linear contact with the sleeve by the roundness expaned outwardly to lessen resistance. Thus, vibration-resisting and shock-resisting properties along the thrust can be improved, thereby to lengthen the life of a video head cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to video disc players, turntables,
The present invention relates to hydrodynamic bearing devices used in various small devices, devices, and products such as video tape recorders.

Structure of conventional example and its problems As the specific structure of the conventional hydrodynamic bearing device is shown in FIG. A fixed shaft 2 having a bearing surface 6 and cantilevered by the main body pace 4, a rigid thrust ring 1 fixed to the free end side of the fixed shaft, and a sleeve rotatably fitted to the fixed shaft. 3, a thrust bearing member 7 fixed to the sleeve and having a spiral group 6 in contact with the front carp bearing surface, and a herringbone type group 8 at two locations near the free end and near the fixed end of the fixed shaft. It was a hydrodynamic bearing device with lubricating oil arranged in these group parts.

In such a configuration, the sleeve 3 moves up and down in response to vibrations and impacts in the thrust direction, and the thrust ring 1
A rubbing phenomenon occurs between the lower end surface 1-a of the sleeve 3 and the end surface 3-a of the thrust ring built-in part of the sleeve 3. This rubbing phenomenon not only deteriorates the rotational accuracy of the sleeve 3, but also causes damage to the hydrodynamic bearing device. This has the disadvantage that it leads to a reduction in service life.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks and provides a hydrodynamic bearing device with a long life and high rotational reliability.

Structure of the Invention The present invention provides a cantilevered fixed shaft having a bearing surface perpendicular to the shaft and having a diameter at least smaller than the shaft diameter on the end face of the free end, and a free end of the fixed shaft. A thrust ring that is fixed to the side and has a thin structure that slightly deforms its shape due to impact force in the thrust direction and absorbs and relieves the force; a sleeve that is rotatably fitted to the fixed shaft; A spiral group is provided on either the thrust bearing member that is fixed and in contact with the bearing surface and the bearing surface or the thrust bearing member, and the shaft or Either side of the sleeve has a herringbone type group, these group parts are provided with lubricating oil, and a sliding part other than the group part of the sleeve is provided with a gap larger than the group part. It is a hydrodynamic bearing device with air holes in the relief part, and the thin-walled thrust ring absorbs and alleviates vibrations and impact forces in the thrust direction, allowing the sleeve to quickly restore stable rotation. This is extremely advantageous in extending the life of the hydrodynamic bearing device.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below. In FIG. 2, 12 is a lower cylinder with a built-in stator portion of the drive source (motor), 13 is fixed to the lower cylinder, and herringbone type groups 16 are provided at two locations near the free end and near the fixed end.
, and a fixed shaft having a bearing surface perpendicular to the shaft and having a diameter smaller than the shaft diameter on the end face of the free end, 9 is fixed to the free end of the fixed shaft, and is shaped by impact force in the thrust direction. A thrust ring having a thin wall structure that absorbs and relieves the force by minutely deforming the shaft; 1o is a sleeve that is rotatably fitted to the fixed shaft and has a rotor portion of a drive source (motor) attached thereto; 11 is the sleeve; an upper cylinder having an integrated rotating video head; 17 is a thrust bearing member fixed to the sleeve and abutting on the bearing surface; a thrust receiver provided with a spiral group 16;
14 is an annular suction magnet that balances the thrust dynamic pressure generated in the spiral group of the thrust receiver, lubricating oil is arranged in each group part of the sleeve, and a gap larger than the group part is provided in the sliding part of the sleeve other than the group part. This is a video head cylinder using a hydrodynamic bearing device, which has a recessed portion and an air hole provided in the recessed portion.

Furthermore, the shape of the thrust ring will be explained with reference to FIG. In contrast to the conventional example, this thrust ring slightly deforms its shape due to the impact force in the thrust direction, has an annular groove 21 in order to absorb and alleviate the impact force, and has a thin connecting part 19. By providing a radius at the tip of the leg, even if there is slight deformation, the contact with the sleeve will be a line contact, thereby minimizing frictional resistance. In this example, in order to comply with product usage standards, the ratio of the depth of the annular groove to the thickness of the connecting portion was set to 6:1, and the R of the tip of the leg was set to % of the width of the leg. However, this ratio shall be selected to have the optimum springiness in accordance with the standard in which the hydrodynamic bearing device is used.

The operation of the hydrodynamic bearing device constructed as described above will be explained below.

When the power switch is turned on, the sleeve begins to rotate due to the stator built into the lower cylinder and the rotor attached to the sleeve, and dynamic pressure is generated by the group in the lubricating oil placed in each group, causing the fixed axis to move in the radial direction. The sleeve levitates and rotates, and the thrust direction is
The thrust receiver and the bearing surface on the free end side of the fixed shaft levitate and rotate.

Therefore, the robot floats and rotates stably in a state where the dynamic pressure in the thrust direction and the attraction force of the annular attraction magnet are balanced. With the above operations, the upper cylinder integrated with the sleeve rotates stably, and the video head attached to the upper cylinder accurately records and plays video tape.

By the way, when vibrations and shocks are applied in the thrust direction, the sleeve moves up and down and tries to push the legs of the thrust ring upwards, but due to the springiness of the thin-walled structure of the connecting part of the thrust ring, the vertical force of the sleeve is reduced. absorb φ and relax. Also, at this time, although the legs spread toward the outer periphery, they are constantly in line contact with each other due to the H at the tip, thereby reducing resistance.

As a result, the vibration and impact resistance in the thrust direction has been improved, and the life of the video head cylinder has been extended.

Effects of the Invention As described above, the present invention provides a thrust ring that is fixed to the free end side of a fixed shaft and that has a thin structure that slightly changes its shape due to impact force in the thrust direction and absorbs and alleviates the force. It is possible to improve the vibration resistance and impact resistance in the thrust direction, and also to provide a long life and high reliability of the hydrodynamic bearing device, which has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional hydrodynamic bearing device, FIG. 2 is a sectional view of a video head cylinder having a hydrodynamic bearing device according to an embodiment of the present invention, and FIG. 3 is an enlarged sectional view of a thrust ring. 9...Thrust ring, 13...Fixed shaft, 10...Sleeve, 17...Mark/Thrust receiver. Name of agent: Patent attorney Toshio Nakao and 1 other person / \ 1 [(- 0

Claims (2)

[Claims] (1) A cantilevered fixed shaft having a bearing surface perpendicular to the shaft and having a diameter at least smaller than the shaft diameter on the end face of the free end, and a fixed shaft fixed to the free end of the fixed shaft. a thrust ring having a thin wall structure to slightly deform its shape due to impact force in the thrust direction and absorbing the force; a sleeve rotatably fitted to the fixed shaft; a thrust bearing member that comes into contact with a bearing surface, a spiral group is provided on either the bearing surface or the thrust bearing member, and the fixed shaft or sleeve is provided at two locations, one near the free end of the fixed shaft and the other near the fixed end. A hydrodynamic bearing device that has a herringbone type group on either side, and lubricating oil is placed in these group parts. (2) A hydrodynamic bearing according to claim 1, wherein the sliding portion of the sleeve other than the group portion has a relief portion for providing a gap larger than the group portion, and the relief portion is provided with an air hole. Device.