JPH0217216A - Dynamic pressure bearing device - Google Patents

Abstract

PURPOSE:To prevent negative pressure from generating on the outskirts of a shaft thrust face by providing at least one of a channel or a hole to a sleeve on a face contacting to the shaft at the thrust face for forming a route in which oil circulates. CONSTITUTION:A shaft 1 is cut with herringbone form of channels 1a in depth about 2-20mum on radial direction, and fitted to a sleeve 2 to turn. An insertion member 3 is formed nearly in a cylindrical form, and is formed with a hole 3a at the center, spiral pattern of channels 3b on a receiving face for the shaft 1, and channels 3c extending in thrust direction on peripheral surface portion. At low.middle revolution speed, oil begins to flow along spiral pattern of channels 3b at first and flows into the hole 3a at the center part. Thereafter oil flows along channels 3d, 3c. Accordingly, oil pressure at the shaft thrust face and the insertion member 3 becomes in pressure distribution as designated in a figure, therefore negative pressure is not generated in neighborhood of the outskirts of the shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an oil-lubricated hydrodynamic bearing device used in video deck heads, record player turntables, and the like.

(Prior Art) As shown in FIG. 6, a conventional oil-lubricated hydrodynamic bearing device includes a shaft 100 having a herringbone-shaped groove 101 on a radial surface and a spiral groove 102 on a thrust surface. This axis 10
The shaft 100 and the sleeve 105 have a sleeve lO5 that holds the oil, and oil is contained in the gap (approximately 2 to 20 ILm) between the shaft 100 and the sleeve 105.

By the way, when the hydrodynamic bearing device is stopped, there is no oil flow, and the shaft 100 and the sleeve 105 are in contact with each other. Then, at the same time as the shaft 100 starts rotating, oil begins to flow in the direction of the arrow as shown in FIG. 7(a).
As the rotation of the shaft 100 gradually increases, the oil flows through the herringbone-shaped groove 101 in the radial surface (b).
) is formed, and the shaft 100 and sleeve 105 are in a non-contact state on the radial surface. On the other hand, as the rotation of the thrust surface increases, the oil flows along the spiral tlt 102 of the thrust surface, and the oil forms a pressure distribution as shown in the same figure (C), which pushes up the weight of the shaft 100. The structure is as follows.

(Problems to be Solved by the Invention) However, in such a conventional example, when a high-speed rotation type is desired to be miniaturized, the following problem occurs. That is, first, the high speed rotation causes the device to become hot, and in the case of oil lubrication, the oil prevents heat radiation. Therefore, a cooling device is required, but if a fan or the like is provided to cool the device body, the cost will increase and a large space will be required. Secondly, if an attempt is made to make the rise time the same at high speed rotation, the starting torque will increase, and wear particles due to metal contact will increase. This abrasion powder accumulates on the periphery of the shaft thrust surface, deteriorating the durability of the device.

Thirdly, when the engine rotates at high speed, the flow of oil becomes faster.
The difference between the high pressure distribution area and the low pressure distribution area becomes extremely large, and negative pressure is generated around the periphery of the shaft thrust surface. As a result, the oil pressure distribution on the thrust surface is disturbed, and the shaft 100 and sleeve 1
05 makes contact on the thrust surface. Thereafter, a movement of 0 or more occurs continuously in an attempt to return to the pressure distribution as shown in FIG. 7(b). This causes vibration and scraping due to metal contact, shortening the lifespan.

Therefore, the present invention was made to solve the above-mentioned problems of the conventional example, and its purpose is to provide a hydrodynamic bearing device that is smaller in size, reduced in cost, and improved in durability. It is about providing.

(Means for solving the problem) In order to achieve the above object, in the present invention, a shaft and a sleeve are fitted together, a shallow groove is formed in at least one of the shaft or the sleeve, and the shaft A hydrodynamic bearing device that supports the radial and thrust directions during rotation by forming a shallow groove in at least one of the end face of the sleeve or the face of the sleeve opposite to the shaft end face, which contacts the shaft of the sleeve at the thrust face. It is constructed by providing at least one of grooves and holes on the surface to form a path through which oil circulates.

(Function) In the present invention having the above configuration, at least one of a groove or a hole is provided on the surface that contacts the axis of the sleeve on the thrust surface, and oil is circulated along the groove or hole as the sleeve rotates. , oil circulates in the thrust direction and no negative pressure is generated on the shaft thrust surface. Therefore, the sleeve and the shaft do not come into contact during one rotation, and the amount of oil can be increased without increasing the resistance between the sleeve and the shaft, thereby suppressing temperature rise.

(Embodiment) The present invention will be explained below based on the illustrated embodiment.1 In Figs. A shaft with a ring-shaped groove 1a carved therein, and 2 a sleeve, into which the shaft 1 is fitted so that either one of them can rotate. In this embodiment, the shaft 1 rotates relative to the sleeve 2. 3 is an insert member formed in a substantially cylindrical shape;
A hole 3a is formed in the center, a spiral pattern groove 3b is formed in the receiving surface of the shaft 1, and a groove 3c (shown in the third figure) extending in the thrust direction is formed in the peripheral surface. A sealing member 4 is press-fitted into the sleeve 2 to seal oil inside the sleeve 2.

To assemble the above hydrodynamic bearing device, first, an insert member 3 as shown in FIG. 3 is press-fitted into the sleeve 2 from the bottom surface of the sleeve. Thereafter, the sealing member 4 is press-fitted, and oil is injected into the sleeve 2. Thereafter, the shaft l is dropped into the sleeve z and the two are fitted together.

Next, the operation of this embodiment will be explained. At low speed rotation, oil flows out along the herringbone-shaped grooves 1a shown in FIG. 1, resulting in a pressure distribution on the radial surface as shown in FIG. 7(C). As a result, the shaft 1 and the sleeve 2 come out of contact in the radial direction. In addition, in the low to medium speed rotation range, the oil first flows out along the spiral groove 3b on the thrust surface.The depth of this groove 3b is shallow, about 2 to 20 JLm, and the oil flows one after another. The pressure increases as you move toward the center of the shaft. here.

Since the insert member 3 has a hole 3a formed in the center thereof, oil flows into the hole 3a. After that, the oil passes through the C-shaped groove 3d formed on the bottom surface of the insert member 3 and further flows along the groove 3C (see Fig. 2 (a).
), therefore.

Because of the oil circulation as described above, the oil pressure on the shaft thrust surface and the insert member 3 has a pressure distribution as shown in FIG. 2(b), so that no negative pressure is generated in the vicinity of the shaft periphery.

4 and 5 show a second embodiment of the present invention, in which the same members as in the first embodiment are designated by the same reference numerals.In this embodiment, an insert member 3 and a sealing member 4 are shown. A porous member 5 is interposed between the two. To assemble the hydrodynamic bearing device of this embodiment, the insert member 3 is press-fitted into the sleeve 2, and the porous member 5 is press-fitted. Then, the sealing member 4 is press-fitted into the sleeve 2. Thereafter, oil is poured into the sleeve 2, and the shaft 1 is dropped onto it.The porous member 5 may be either integrated with the insert member 3 or separated.

Therefore, in the second embodiment, by interposing the porous member 5 in at least a portion of the oil circulation path, the porous member 5 has a filter function and can remove wear particles in the oil.

In addition, the above 1. In the second embodiment, an insert member provided with at least one of a groove or a hole for circulating oil is used, but it is also possible to circulate oil by forming grooves or holes in the sleeve itself without using an insert member. .

As described above, in each of the above embodiments, oil circulation is possible not only in the circumferential direction of the radial surface but also vertical circulation in the thrust direction, and negative pressure is no longer generated due to oil circulation on the thrust surface of the shaft. . This eliminates contact between the sleeve and the shaft that occurs during rotation, making it less likely that vibrations or uneven rotation will occur. In addition, the oil circulation is improved and the amount of oil can be increased without increasing the resistance between the sleeve and the shaft due to the oil, so temperature rise can be suppressed.

Additionally, the oil circulation reduces scuffing caused by wear debris.

By the way, in order to have a linking function on the thrust surface,
There are methods such as forming holes or grooves in the shaft, but as the device becomes smaller, the shaft becomes thinner, with a diameter of 2 to 3 intestinal layers.
It is difficult to machine them into shafts. Additionally, if the holes and grooves are machined after machining the herringbone-shaped grooves that determine the flow of shaft oil, accuracy will deteriorate, but in each of the above embodiments, by press-fitting the insert member after machining,
Processing becomes easier, and as a result, costs can be reduced.

(Effects of the Invention) The hydrodynamic bearing device according to the present invention has the above-described configuration and operation, and since negative pressure is not generated at the periphery of the shaft thrust surface due to oil circulation on the thrust surface, vibration and rotational irregularities are prevented. This greatly improves durability. Also,
Since temperature rise can be suppressed without providing a cooling device, costs can be reduced and downsizing can be achieved. Furthermore, the ease of processing has the effect of significantly reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention. FIGS. 2(a) and 2(b) are enlarged sectional views of the insert member and its surrounding area in the same example, its pressure distribution diagram, and FIG.
Figures (a), (b), and (C) are a plan view, side view, and bottom view of the insert member in the same embodiment, Figure 4 is a vertical cross-sectional view showing the second embodiment of the present invention, and Figure 5 is a vertical sectional view showing the second embodiment of the present invention. An enlarged sectional view of the porous member and its surrounding area in the same example, FIG. 6 is a longitudinal sectional view showing a conventional hydrodynamic bearing device, and FIGS. 7(a) and (b)
, (c) are a sectional view showing oil flow, a pressure distribution surface in the radial direction, and a pressure distribution diagram in the thrust direction in the same conventional example. Explanation of symbols 1...Shaft a...Groove 2...Sleeve 3...Insert member 3a...Hole b...Groove 4...Sealing member 5...Porous member Fig. 3 Figure (σ) (0> Figure 5 Figure 6 Figure 6 (O) (c')

Claims (3)

[Claims] (1) The shaft and the sleeve fit together, and a shallow groove is formed in at least one of the shaft or the sleeve, and a shallow groove is formed in at least one of the end surface of the shaft or the surface on the sleeve side facing the shaft end surface. In a hydrodynamic bearing device that supports the radial and thrust directions during rotation, at least one of a groove or a hole is provided on the surface that contacts the shaft of the sleeve in the thrust surface to form a path for oil circulation. Characteristic hydrodynamic bearing device. (2) The hydrodynamic bearing device according to claim 1, wherein the path through which the oil circulates is formed by an insert member. (3) The hydrodynamic bearing device according to claim 1 or 2, wherein a porous material is interposed in the path through which the oil circulates.