JPH02118215A - Fluid bearing device - Google Patents

Abstract

PURPOSE:To obtain the high speed and long life of the captioned device by holding a lubricant between a shaft end face and a thrust receiving member and fixing a ring which has a small gap coaxial with a shaft while being in contact with a sleeve and the thrust receiving member and which is impregnated with a lubricant. CONSTITUTION:As a rotary shaft 1 is rotated, a lubricant 8 is collected to the center of a shaft end face 1b by means of grooves 5a for generating dynamic pressure of a thrust board 5 to float up the shaft 1. The lubricating oil 8 in the vicinity of the surface of the shaft end face 1b tends to flow out along the outer periphery of shaft due to centrifugal force. At this time, the lubricant filled in a thrust ring 4 is drawn into a shaft center in the vicinity of the thrust board 5 while, on the contrary, the lubricant is drawn into the thrust ring 4 on the portion opposite to the shaft surface 1a, thereby, circulating the lubricant 8 through the inside of the thrust ring 4. Hence, the flow-out of the lubricant can be made minimum obtaining the high speed and long life of a device. It is also possible to use a similar structure in a radial bearing.

Description

[Detailed description of the invention] The present invention relates to a hydrodynamic bearing device used in bearings such as the above.

Conventional technology In the past, various hydrodynamic bearing devices have been devised and provided to improve the performance of various spindle devices.
In response to the demand for longer life, it was necessary to take some countermeasures.

In general, the performance of hydrodynamic bearings is affected by deterioration of lubrication performance, that is,
The amount of lubricating oil decreases due to deterioration, scattering, evaporation, or leakage due to thermal convection, so it is lost in proportion to the usage time. This effect is particularly noticeable on thrust bearings that are subjected to high loads, and therefore, structures have been proposed in which an oil reservoir is provided to retain oil or grease, or a structure is proposed in which lubricant that attempts to flow out is pushed back into the bearing.

The conventional technology will be explained below with reference to FIGS. 5 to 8.

In FIG. 5, a rotating shaft 1 is rotatably fitted into a sleeve 2, and groups 6a and 6b for generating dynamic pressure are provided. A thrust receiver 5 is fixed to the sleeve 2 in contact with the shaft end surface 1b of the rotating shaft 1, and a ring 9 for an oil sump is attached.
is fixed concentrically to the rotating shaft 1 by a sleeve 2 and a thrust receiver 5. 7 is a ring for preventing the rotating shaft 1 from being removed.

FIG. 6 is a plan view of the thrust receiver 5, in which a group 5a for generating dynamic pressure is provided on the surface that comes into contact with the shaft end surface 1b of the rotating shaft 1.

The operation will be explained below.

When rotating shaft 1 starts rotating, group 6 a + 6 b
.

5a generates dynamic pressure, and the rotating shaft 1 floats above the thrust receiver 5 and rotates without contacting the sleeve 2.

This is because, as shown in FIGS. 7 and 8, the lubricants 8 and 10 are concentrated at the center of each group by the action of the groups 5a and 6, thereby generating dynamic pressure.

At this time, as shown in FIG. 7, the lubricant 8 receives centrifugal force f and tends to be scattered outward. Similarly, a portion of the lubricant 8 tends to escape upward along the rotating shaft 1 due to centrifugal force, and therefore the lubricant 8 between the shaft end surface 1b and the thrust plate 5 tends to decrease.

If the operation is continued under such conditions, the lubricant 8 will decrease, and eventually the flying height will decrease, causing contact rotation between the rotating shaft end face 1b and the thrust receiver 5, which will significantly impair bearing performance. Become.

Therefore, by providing a ring 9 and setting the gap between the inner periphery of the ring 9 and the outer periphery of the rotating shaft 1 to an appropriate level (0.05 to 0.2 ww), scattering due to centrifugal force is prevented, and the lubricant 8 is to prevent it from flowing out from the thrust part.

Further, by providing a group 1c on the outer periphery of the shaft 1 facing the ring 9 so as to transport the lubricant 8 toward the shaft end surface 1b, the grease that tends to flow out along the surface of the shaft 1 is pushed back and the lubrication is improved. To prevent the agent 8 from coming out from the thrust part.

The above operations aim to improve bearing life.

Problems to be Solved by the Invention However, the conventional configuration has the following problems.

Generally, as the speed and load increase, the temperature of the bearing increases and the quality of the lubricant (lubricating oil) changes (thermal deterioration).The viscosity increases due to oxidation and the lubricant (lubricating oil) flows out due to temperature gradients (thermal capillary phenomenon). , or the so-called Marangoni effect). As shown in FIG. 7, the temperature is highest at the center of the group 5a, and the temperature gradually decreases toward the periphery.

In such a state, the lubricant 8 flows out through the gap between the ring 9 and the sleeve 2, or flows out along the surface of the shaft 1.

Similarly, as shown in FIG. 8, in the case of a radial bearing, lubricant gradually flows out from both end portions 11a and 11b of the group.

In addition, the lubricant 8 of the thrust bearing, which is generally subjected to high loads, is
Grease is generally used for
At high speeds, the thickener is separated and the separated thickener collects on the outside of the group 5a or on the inner periphery of the ring 9 (generally, the specific gravity of the thickener is larger than that of the base oil), which reduces the circulation of the lubricant 8. is inhibited, and the deterioration of the lubricant 8 progresses more and more.

As a result of the above, the performance of the bearing deteriorates significantly.

As a countermeasure to the above, it has also been proposed to seal using a magnetic fluid seal, etc., but this does not work well under conditions such as high speed and low pressure, and is expensive.

As mentioned above (1) Lubricant cannot be retained at higher speeds and higher temperatures.

(There is some lubricant leakage even at low speeds.) (2) This is not an effective measure against lubricant deterioration.

(3) It is insufficient to extend the service life.

There were other issues that needed to be resolved.

Means for Solving the Problems In order to solve the above conventional problems, the present invention provides (1) a lubricant is held between the shaft end surface and the thrust receiving member, and a microscopic lubricant is held near the shaft end surface concentrically with the shaft. A lubricant-impregnated ring is fixed in contact with the sleeve and the thrust receiving member with a large gap, and (2) dynamic pressure is generated on either the outer circumference of the shaft or the inner circumference of the sleeve. The lubricant is held in the group, and the sleeve is provided with a ring impregnated with the lubricant at least one of both ends of the group.

Effect In the configuration (1) above, when the shaft rotates, dynamic pressure is generated between the shaft end face and the thrust receiving member, a low pressure area is generated on the outer periphery of the shaft end face, and the lubricant is drawn out from the ring impregnated with lubricant. . At the same time, the lubricant scattered by centrifugal force is drawn into the ring again. As described above, the lubricant is circulated through the ring, thereby preventing the lubricant from flowing out.

Similarly, in the configuration (2) above, when the shaft rotates, dynamic pressure is generated by the action of the group, and the shaft rotates without contact. At this time, low pressure is generated to draw in oil at both ends of the group, drawing lubricant from the lubricant-impregnated ring. In addition, lubricant that flows out from the outer periphery of the group due to centrifugal force or thermal scent, or is pushed out to the outer periphery of the group due to the squeezing action caused by whirling during startup/stop.
The lubricant is absorbed into the ring again and through a series of operations provides the effect of preventing the lubricant from flowing out of the bearing.

As a result of the above-described effects, the present invention provides a bearing device that can prevent the lubricant from flowing out from the bearing portion, as well as circulate and replenish the lubricant, thereby increasing the speed and extending the life of the lubricant.

EXAMPLE An example of the present invention will be described below using FIGS. 1 to 4.

Incidentally, the same constituent functions as those of the conventional example are given the same reference numerals and the explanation thereof will be omitted.

In FIG. 1, 3a, 3b, and 4 are rings each impregnated with lubricant (lubricating oil). The rings 3a and 3b are press-fitted into the sleeve 2, and the thrust ring 4 is connected to the sleeve 2 and the thrust plate 5. are abutted and fixed.

The operation will be explained below using FIGS. 2 to 4.

2 and 3 are enlarged views of the thrust bearing section.

In FIG. 3, when the rotating shaft 1 starts rotating, due to the action of the group 5a provided on the thrust plate 5 for generating dynamic pressure,
The lubricant 8 is collected at the center of the shaft end face 1b, increasing the pressure and causing the shaft 1 to float. The lubricating oil 8 near the surface of the shaft end face 1b is carried outward by centrifugal force and tends to flow out along the outer circumference of the shaft. At this time, the lubricant impregnated in the thrust ring 4 is drawn into the center of the shaft near the thrust plate 5, and conversely, the lubricant coming out from the shaft end surface 1b is drawn into the thrust ring 4 at the portion facing the surface 1a of the shaft 1. Pull inside. Generally, such a ring is made of a porous sintered alloy, so the lubricant 8 circulates through the thrust ring 4 at the thrust portion, as shown in the figure. This circulation also occurs under the temperature gradient shown in FIG. This is because the inside of the thrust ring 4 is filled with lubricant, so the temperature is always lower than that in the center of the thrust, so it is possible to prevent the lubricant from flowing out due to scattering due to heat smell or centrifugal force.

Further, since the thrust bearing usually receives the weight of the rotating body, the load is larger than that of a radial bearing, and therefore, grease is used as the lubricant 8. At this time, by impregnating the thrust ring 4 with the base oil of the grease used for the lubricant 8, even if the grease separates from the thickener due to centrifugal force or heat (generally 60°C to 80°C or higher), Because base oil is constantly supplied by the action of the thrust ring 4, it is turned into grease again and functions without impairing its extreme pressure properties.

Next, the operation of the radial bearing will be explained.

In FIG. 4, when the rotating shaft 1 starts rotating, the lubricant 10 in the gap 11 with the sleeve 2 is gathered at the center of the group 6a due to the action of the group 6a provided on the rotating shaft 1, and the movement of the lubricant 10 is Due to the pressure, the rotating shaft 1 rotates without contact.

In this example, the gap 11 with the sleeve 2 is formed only in the vicinity of the group 6a to reduce rotational friction torque, and similarly the ring 3a has a gap slightly wider than the gap 11.
(approximately 10 μl to 0.1 w) and is fixed to the sleeve 2.

At this time, due to centrifugal force and heat smell, around the group 11a, l
lb of lubricant 10 tries to come out, but the ring 3a impregnated with lubricant 10 pulls it in and circulates it in the same way as the thrust ring 4. Also around the group 1
In 1a, lubricant is drawn in by ring 3a.

As mentioned above, the rings 3a, 3b and the thrust ring 4
This function not only prevents the lubricant from flowing out (usually only a small amount of lubricant, several tens of μQ, exists in the voids near the group, but it actually holds tens of times more lubricant than that), and the lubrication The structure is designed to deal with deterioration and evaporation of the agent.

In addition to the effects of the invention, the present invention provides the following effects. That is, (1) the outflow of the lubricant can be minimized, so the life can be extended.

(2) Since it is possible to prevent lubricant from scattering due to centrifugal force and flowing out due to heat smells that occur at high speeds and high loads, it is possible to operate at higher speeds and higher loads than conventional hydrodynamic bearings. .

(3) Complicated configurations such as magnetic fluid seals and lubricant circulation structures are not required, allowing the bearing to be made smaller and lower in cost.

(4) The amount of lubricant can be substantially reduced without increasing bearing loss, leading to longer life.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIGS. 2 and 3 are enlarged cross-sectional views and operation explanation diagrams of the thrust section, and FIG. 4 is an operation explanatory diagram of the radial section in FIG. Fig. 5 is a sectional view of the conventional example, Fig. 6 is the thrust 1-Fig.
, 3b...Ring, 4...Thrust ring, 5...Thrust plate, 5a...
Plane group, 6 a, 6 b... Circumferential group, 7... Removal stop ring, 8...
First lubricant, 10...Second lubricant. Name of agent: Patent attorney Shigetaka Awano and one other person Figure Figure Figure Figure (b)

Claims (6)

[Claims] (1) A shaft, a sleeve constituting a bearing for the shaft, and a thrust receiving member disposed opposite to the thrust end surface of the shaft and fixed to one end surface of the sleeve, the thrust receiving member and the shaft a first lubricant held between the end face and the shaft end face, a first lubricant disposed concentrically with the shaft with a small gap therebetween, and abutting the sleeve and the thrust receiving member; A hydrodynamic bearing device comprising a thrust ring impregnated with a second lubricant, the second lubricant being held in the gap. (2) The hydrodynamic bearing device according to claim 1, wherein the first lubricant has a higher viscosity than the second lubricant. (3) The hydrodynamic bearing device according to claim 1 or 2, wherein a spiral group is provided on either the shaft end face or the contact face of the thrust receiving member. (4) A group that generates dynamic pressure is provided on either the outer periphery of the shaft or the inner periphery of the sleeve, a lubricant is held in the group, and the lubricant is placed in the sleeve near at least one of both ends of the group. A hydrodynamic bearing device with a radial ring impregnated with the same lubricant. (5) The hydrodynamic bearing device according to claim 4, wherein the gap between the radial ring and the shaft is larger than the gap between the shaft and the sleeve. (6) The hydrodynamic bearing device according to claim 4 or 5, wherein the gap between the shaft and the sleeve is formed to be narrowest near the group, and the lubricant is held only near the group by the force of capillary action. .