JPH0438102Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is a dynamic pressure rotating body, in other words, a lubricating fluid is interposed between the circumferential surface of the spindle and the inner circumferential surface of the shaft hole inserted into the spindle, The present invention relates to a rotating body that is supported in a floating state from the support shaft by the pumping action of the lubricating fluid.

(Prior Art) As a device to which a dynamic pressure rotating body is applied, there is a rotating cylinder assembly including a head for a video tape recorder (VTR).

The following is an explanation of this assembly.

In FIG. 6, which shows a rotary cylinder assembly including a head for a VTR, a rotary cylinder 52 having a head 51 has a screw 55 attached to a rotary disk 54, which is a rotating body rotatably supported on a central shaft 53.
A magnet case 57, which has a rotor magnet 56 fixed to its inner circumferential surface, is mounted on the lower surface of the flange portion 54a of the rotary disk 54, and is screwed in such a way as to sandwich one transformer 58 of the rotary transformer. It is fixed at 59.

The fixed cylinder 60 is fixed to the open end of a housing 61 in which the central shaft 53 is installed, and within this fixed cylinder 60, the other transformer 62 of the rotary transformer is placed with a minute gap from the one transformer 58. Fixed.

On the bottom plate of the housing 61 is a drive coil 65 made of a laminated plate that cooperates with the rotor magnet 56.
A stator 63 having a structure is fixed with screws 66 via a support 64.

The rotary transformers 58 and 62 are used to transmit signals from the head 51 from the rotating side to the stationary side of the rotary cylinder assembly without contact, and are mainly composed of a stator 63 and a rotor magnet 56. They are arranged in line with the motor in the axial direction.

On the other hand, the central axis 53 has two
Spiral grooves G for dynamic pressure are carved at the locations, and a lubricating fluid such as oil is interposed between this groove and the inner hole of the rotary disk 54.
The rotating disk 54 is floated by oil around the central shaft 53 by the pumping action generated by the rotation of the rotary disk 54, and is pivotally supported.

(Problem to be solved by the invention) By the way, in the above-mentioned configuration, the central axis 5
3. In other words, a groove is formed on the fixed shaft, and the rotary disk 54 on the rotating side has an inner hole with a smooth inner surface, that is, a mirror finish, so that the rotary disk 54 rotates. However, the fluidity of the lubricating fluid interposed in the gap between the circumferential surface of the center axis and the inner hole of the rotary disk 54 is determined only by the frictional action between the inner hole surface and the lubricating fluid within the groove. This will not allow for smooth movement,
In other words, it is difficult to move, and therefore the desired pumping action cannot be obtained, resulting in a problem that the efficiency of the bearing function due to the dynamic pressure action is poor.

Moreover, when grooves are carved on the circumferential surface of the central shaft 53, only the groove portions are melted using a photo etching method using a special solvent.
Because it forms grooves with a depth of about 10 μm,
There is a risk that the number of processing steps and furthermore the processing time will increase, leading to an increase in work costs.Furthermore, the grooves obtained by etching may be dish-shaped with vertical walls on the side edges. As a result, the fluidity of the oil within the grooves, including the ability to discharge the oil from the grooves, deteriorates, resulting in a problem that the efficiency of the dynamic pressure action is poor.

(Means for Solving the Problem) The present invention provides a structure in which a lubricating fluid is interposed between two surfaces that move relative to each other, that is, a shaft circumferential surface and a bearing-side inner circumferential surface to form a hydrodynamic bearing. The side is the rotating side, a group of grooves parallel to the direction of relative motion are formed on the inner bore surface of the bearing, and an oil sump portion communicating with the group of grooves is formed on at least one side of the group of grooves. The problems of dynamic pressure rotating bodies were solved by this method.

(Operation) When the bearing on the rotating side rotates, the group of grooves moves due to the rotation, so lubricating fluid flows into the groove from the oil reservoir and flows within the groove, causing a pumping action by the group of grooves. As a result, a hydraulic film is formed in the gap between the circumferential surface of the shaft and the inner hole surface of the rotary disk, thereby supporting the rotary disk in a floating state relative to the shaft.

(Example) FIG. 1 shows a rotating cylinder assembly which is an example of applying the rotating body of the present invention.

In FIG. 1, a rotor magnet 10 is fixed to the inner circumferential surface of a rotor case 12 made of a cylindrical body with end plates, and the rotor case 12 has a flange 1.
It is fixed to a rotary disk 13 which is a rotating body having a rotor 3a. The rotary disk 13 is rotatably fitted onto a shaft 15 implanted and fixed in the center of a fixed cylinder 14 constituting a rotary head portion of the VTR. A spiral groove 16 for a dynamic pressure bearing, which will be described in detail later, is formed on the inner surface of the shaft hole of the rotary disk 13, and a thrust bearing plate 17 is formed on the end surface of the shaft 15.
is in contact with. The thrust bearing plate 17 is connected to the shaft 15
A groove for dynamic pressure (not shown) is formed in the contact surface with the rotary disk 13, and is fixed to the end surface of the rotary disk 13 by a presser plate 18 applied to the outer surface of the groove. The holding plate 18 is fixed to the top of the rotary disk 13 by screws 19. The structure of the contact surface between the thrust bearing and the shaft has a groove for dynamic pressure, and one of the structures is as shown in FIG. There is a thrust bearing or a presser end plate 170 in which an annular groove 170a for dynamic pressure is formed, and the shaft end is brought into contact with the central land portion of the annular groove 170a.

A rotary cylinder 20 constituting a rotary head is attached to a flange 13a of the rotary disk 13 with a screw 21.
This rotary cylinder 20 has a
A head 22 is attached via a support 23. The inner end of an azimuth adjustment screw 24 screwed into the rotary cylinder 20 is in contact with the surface of the support body 23 that is in contact with the rotary cylinder 20 .

A stator core 11 made of a laminated plate is fixed to a fixed cylinder 14 having a shaft 15 implanted therein by a screw 26 with an isolation cylinder 25 in between, and a drive coil 27 is provided in the stator core 11. A wiring board 28 is fixed to the isolation tube 25, and a Hall element 29 is supported by the wiring board 28 and is disposed at a position facing the inner peripheral end of the rotor magnet 10. .

The rotating side transformer 30 of the rotary transformer has a substantially annular shape and is fixed to the outer peripheral surface of the rotor case 12 with an adhesive. On the other hand, the fixed side transformer 31 is connected to the rotating side transformer 30 and 40~
They are fixed to the stepped portion of the fixed cylinder 14 with a surface spacing of 50 μm.

And the shaft hole 13b of the rotary disk 13 mentioned above.
As shown in FIG. 3, on the inner surface of the
is formed on the shaft hole opening side.

Shaft hole 13b in which this groove 16 is formed
As shown in FIG. 2, the inner periphery of the shaft 15 is set to have a slightly larger diameter than the outer diameter of the shaft 15, and the inner periphery between each groove 16 in the axial direction is larger than the groove forming portion described above. The inner diameter of each groove 16 is set to be larger, and on both sides of each groove 16 in the axial direction, there are oil reservoir portions 1 which are sunk in a substantially conical shape and communicate with each groove 16, as shown in FIG.
3c is formed.

The rotary disk 13 is made of a metal material with lower hardness than the shaft 15, such as brass or gunmetal, and the groove 16 allows a tool having a plurality of balls or teeth protruding from the circumferential surface to be inserted into the shaft hole 13b. In addition to inserting it in a press-fitting state, rolling or cutting is performed by relatively displacing the tool or rotary disk 13 so that it has a wedge-shaped shape shown in FIG. 3 with a depth of several μm to several tens of μm. It is formed as a result.

Note that the rotating disk 13 is not limited to brass or gunmetal, but may be made of other metal materials or resins as long as they have a property of being lower in hardness than the shaft 15, and the method of forming the group may also be used. Of course, other methods may also be used.

In this configuration, oil as a lubricating fluid is interposed between the circumferential surface of the shaft 15 and the groove 16, as shown in FIG.

Therefore, when the rotary disk 13 is rotated by a motor or the like, the groove 16 moves, so that oil flows into the groove 16.

Since the groove 16 is set in a wedge-like shape, the oil in the groove 16 is concentrated at the tapered part, increasing the accumulated pressure at that part, and as a result, it flows out toward the circumferential surface of the shaft 15. Then, it is discharged to produce a pumping action, forming a hydraulic film in the gap between the shaft 15 and the groove 16, and the rotary disk 13 is levitated relative to the shaft 15 by this film.

The rotary disk 13 is rotated in this state.

At this time, the oil existing between the shaft 15 and the groove 16 flows into the gap between the shaft peripheral surface and the inner hole peripheral surface of the rotary disk 13 due to the pumping action, and is located on both sides of the groove 16. Oil reservoir part 13
It is returned to c.

The oil returned to this oil sump 13c is guided again into the groove 16 communicating with it, and thereafter, by repeating the pumping action and returning to the oil sump, the oil returns to the oil sump 13c. circulate between.

(Effects) As described above, according to the present invention, in a shaft and a bearing that are in a relative motion relationship, the bearing side is the rotating side, a groove for dynamic pressure is formed on the inner peripheral surface of the shaft hole on the rotating side, and the groove is Since an oil reservoir is formed on at least one side of the groove and the oil reservoir is communicated with the groove, the movement of the groove improves the fluidity of oil within the groove. This increases the oil circulation efficiency between the groove and the oil reservoir, making it possible to obtain a pumping action with extremely high efficiency.Moreover, machining of the bearing side, which is the rotating side, such as the flange part, etc. When performing machining, it is possible to machine the part that performs the pumping action while processing it, and it is also possible to cut and roll the groove and oil sump part against the machining reference plane of the bearing. Therefore, there is no need for special processing steps, and cost reductions can be achieved by improving work efficiency.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing a rotating cylinder assembly to which an embodiment of the present invention is applied, Fig. 2 is a local sectional view showing the main parts of the embodiment of the invention, and Fig. 3 is a main part of the embodiment of the invention. FIG. 4 is a partial sectional view showing the operation of the main parts of the embodiment of the present invention, FIG. 5 is a schematic sectional view showing a part of the rotating cylinder assembly shown in FIG. 1, and FIG. 1 is a schematic cross-sectional view showing a conventional example of a dynamic pressure rotating body. 13...Rotating disk, 13b...Shaft hole, 13
c...Oil sump, 16...Groove.

Claims (1)

[Claims for Utility Model Registration] A rotating body that has a shaft hole inserted into a fixed shaft and rotates around the shaft, for generating dynamic pressure on the inner peripheral surface of the shaft hole of the rotary body. A groove is formed on at least one side of this group, and a reservoir portion for storing a lubricating fluid interposed between the circumferential surface of the shaft and the inner circumferential surface of the shaft hole, and the reservoir portion and the groove A dynamic pressure rotating body that communicates with the