JPH10281147A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of frictional powder generated by being brought into contact a ball and a shaft with each other, and ensure smooth performance by arranging a plurality of balls between a locus groove arranged on a thrust receiving surface and a locus arranged on a thrust bearing surface. SOLUTION: In a bearing device, a locus groove 2a which is concentrically with an outer diameter surface of a shaft is arranged on a thrust receiving surface 2b as an end surface of a shaft 2, radial bearing surfaces 5b are arranged on an inner diameter surface of a sleeve 5 and on two positions separated in an axial direction, and a radial receiving surface 2c provided with a groove for generating dynamic pressure is formed on the shaft 2. When current- carrying is carried out to a motor, a rotary magnetic field is generated, a rotor is rotated, and a rotary member provided with a housing 3 is driven, a plurality of balls arranged between the thrust receiving member 4 and the shaft 2 are rotated while being brought into rolling-contact. The clearance between three or more balls 1 is held to a constant level, and the rotation of the thrust receiving member 4 is smoothly carried out. It is thus possible to reduce a torque, and it is also possible to prevent generation of frictional powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device used for information equipment and the like, and more particularly to an improvement of a bearing device used for an HDD and the like.

[0002]

2. Description of the Related Art A conventional dynamic pressure bearing device is shown in FIGS. In FIG. 3, a housing 15 as a rotating body has a sleeve 16 and a thrust receiving member 17 formed of a ball attached to one end of the sleeve 16, and is rotatably fitted to the shaft 14.

[0003] The inner diameter surface of the sleeve 16 is two axially spaced apart.
There are radial bearing surfaces 18 on a cylinder at several places, and the thrust receiving member 17 has a thrust bearing surface 19. On the other hand, the shaft 14 fitted to the sleeve 16 has a radial receiving surface 20 facing the radial bearing surface 18 via a radial bearing clearance, and a thrust surface 21 facing the thrust bearing surface 19 in contact therewith. doing.

The radial receiving surface 20 is provided with a groove 25 having a herringbone shape. When the housing 15 rotates, the pressure of the lubricant in the radial bearing clearance increases due to the pumping action of the herringbone-shaped groove 25 of the shaft 14, and the sleeve 16 is supported with the shaft 14 kept in non-contact in the radial direction. . At the same time, the ball of the thrust receiving member 17 contacts the thrust receiving surface 21 of the shaft 14 and is supported in the axial direction.

[0005] Since the ball and the shaft rotate by direct contact with each other, there is a danger that wear occurs and the life of the bearing is shortened.
In particular, there is also a problem that when the thrust bearing wears, the wear powder is sucked into the radial bearing and the operation of the radial bearing stops (the locked state of the radial bearing).

FIG. 4 is a sectional view of a conventional hydrodynamic bearing device. When the rotating member rotates, the pumping action of the two herringbone grooves, 72A and 72B, increases the pressure of the lubricant 80 of the radial bearing, and rotates from the initial contact state to the non-contact state.

At the same time, the thrust bearing lubricant 7 is formed by the pumping action of the spiral groove 75A on the end face of the shaft 72.
The pressure of 9 is increased to overcome the suction force of the motor rotor 81, and the rotating member floats by a certain amount from the upper end surface of the shaft 72 and rotates from the contact state to the non-contact state.

However, in this structure, the thrust hydrodynamic bearing does not float at the beginning of rotation, and has a drawback in that the driving torque is large. Further, the same problem as the structure shown in FIG. 3 arises because the influence of wear powder at the time of initial levitation leading to an increase in the initial driving force can be considered.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problem that the thrust bearing is a ball bearing and the torque at the time of contact between the ball and the shaft is increased, and the ball and the shaft are brought into contact with each other. It is an object of the present invention to provide a bearing device that prevents the generation of generated wear powder and ensures smooth operation.

[0010]

According to a first aspect of the present invention, a housing includes a sleeve and a thrust receiving member attached to one end of the sleeve, and the inner diameter surface of the sleeve is cylindrical at two locations separated in the axial direction. The thrust receiving member has a thrust bearing surface, and the shaft fitted to the sleeve has a radial receiving surface facing the radial bearing surface and a thrust receiving surface facing the thrust bearing surface. In a bearing device in which a groove for generating dynamic pressure is provided on at least one of the radial bearing surface and the radial receiving surface, a plurality of races are provided between the raceway groove provided on the thrust receiving surface and the raceway provided on the thrust bearing surface. A bearing device provided with balls is provided.

With this structure, the thrust bearing becomes a ball bearing. That is, the shaft is provided with a raceway groove for receiving the ball, and the shaft and the thrust receiving member are in contact with each other so that the reduction of torque and the generation of wear powder can be suppressed.

An adverse effect on the rotational accuracy of the ball bearing is caused by providing a raceway groove concentric with the outer diameter surface of the shaft on the thrust receiving surface, which is the end surface of the shaft, because the raceway groove is prevented from being eccentric with respect to the outer diameter surface of the shaft. Does not occur.

In the present invention, since the raceway groove concentric with the shaft outer diameter surface is provided on the thrust receiving surface which is the end surface of the shaft, the thrust bearing surface of the housing can be used as a bearing device regardless of whether it is a flat raceway or a raceway raceway. Function can be performed. Further, by making the groove radius of the raceway groove larger than that of the standard thrust ball bearing, it is possible to reduce the radial displacement in which the rotating member is affected by the thrust ball bearing.

Further, the bearing device of the present invention has a structure that can be applied to both cases where the housing is rotated with the shaft fixed and the shaft is rotated with the housing fixed. In either structure, the thrust bearing has a ball bearing structure.

Further, the thrust bearing is provided in a direction in which a centrifugal force acting on one ball generated by rotation of the housing or the shaft and an axial force applied by one ball to one of the housing and the shaft. The contact angles can also be matched.

In the thrust ball bearing, there is a possibility that the ball is displaced outward due to centrifugal force. Originally, the ball is in rolling contact with the raceway groove, but when the rolling speed gradually increases, the action of centrifugal force acts.

FIG. 5 is a sectional view showing the state of rotation of the ball in the raceway groove. As shown therein, when the action of the centrifugal force becomes stronger, the raceway grooves 9 provided in the thrust bearing surface 90 are provided.
The ball 92 between the 3 and the raceway groove 94 provided on the thrust receiving surface 91 is moved radially outward from the center of the raceway grooves 93 and 94. In such a position, the ball easily comes into sliding contact with the raceway groove. further,
Abrasion occurs due to sliding contact at that portion.

Therefore, the balance between the centrifugal force of the ball and the own weight of the rotating member is measured, the contact angle is provided on the thrust ball bearing, and the ball easily rolls into the raceway groove. That is, if the ball contacts the shaft and the housing on a straight line including the center of the ball, rolling contact is facilitated. With this structure, sliding contact is reduced, and occurrence of wear can be prevented. Further, since the radial displacement of the ball is small, the axial displacement and vibration of the rotating member are small. With such a structure, the raceway diameter of the thrust bearing surface and the raceway diameter of the thrust bearing surface are different.

FIG. 2 is a partially enlarged view of the bearing device in consideration of the centrifugal force in the present invention. 90 ° for thrust ball bearings
The contact angle is different from that of the above, and the diameter of the raceway between the raceway groove of the shaft and the raceway groove of the housing is changed. However, in general, the contact angle of the thrust ball bearing is 90 °.

The contact angle β is an angle between the line of action of the resultant force transmitted to the ball 1 and a plane perpendicular to the axis 2 as shown in FIG.

Here, W: own weight of the rotating member N: number of balls f ₀ : normal force at the contact point between the ball and the raceway groove f _i : normal force at the contact point between the ball and the raceway groove μ: friction coefficient β: Contact angle α: 90 °-β _fe : Centrifugal force acting on one ball Assuming the axial component force, the following equation (1) is obtained.
The following equation (2) is obtained from the component force in the radial direction.

[0022]

(Equation 1)

[0023] (1) (3) of the following except formula and the f ₀ and f _i are substituted into the formula (2) is obtained.

[0024]

(Equation 2)

Here, W: 60 to 80 grf N: 3 pieces _fe : mrω ² = 0.12 grf (where, m: weight of one ball, r: ball revolution radius, ω: ball angular velocity) μ: 0.1 Assuming that 001 is 0.001 to 0.003, the center of the range of α is about 30 ° from the equation (3)
And the center of the range of the contact angle β is about 60 °.

[0026]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the bearing device of the present invention. The bearing device includes components of a ball 1, a shaft 2, and a housing 3. In particular, the housing 3 includes a thrust receiving member 4, a sleeve 5, a lid 7, and a bolt 8.

In this bearing device, a raceway groove 2a concentric with the outer diameter surface of the shaft is provided on a thrust receiving surface 2b, which is the end surface of the shaft 2, so that the ball 1 can move around. When forming the raceway groove 2a, it is necessary to consider the rotational accuracy of the bearing device. Therefore, the groove is formed directly on the thrust receiving surface 2b, and the eccentricity with respect to the shaft outer diameter surface is minimized. .

Similarly to the shaft 2, the plate-shaped thrust receiving member 4 has a thrust bearing surface 4 opposing the thrust receiving surface 2b.
The raceway of the raceway groove 4a is machined in c to have the same raceway diameter as the raceway groove 2a formed on the thrust receiving surface 2b. However, in the embodiment of the present invention, the housing 3
Although the raceway groove 4a of the housing is provided on the thrust bearing surface 4c of the thrust receiving member 4 which is a part of the above, a flat raceway (not shown) may be used instead of the raceway groove 4a. This is because as long as the raceway of the raceway groove 4a or the flat raceway is provided on the thrust bearing surface 4c, the ball 1 can oscillate and function as a bearing device.

With respect to the raceway diameter of the raceway groove, the raceway diameter of the raceway groove 2a provided on the thrust receiving surface 2b and the raceway diameter of the raceway groove 4a of the thrust bearing surface 4c may be equal or different. Is desirable. In particular, when considering the centrifugal force, if one of the track diameters is larger than the other track diameter, a contact angle other than 90 ° is generated, and the ball is easily contacted by the track groove. The raceway diameter of the raceway groove 2a of the thrust receiving surface 2b is determined by the thrust bearing surface 4c.
Is smaller than the orbit diameter of the orbit groove 4a. However, the raceway diameter of the raceway groove 4a of the thrust bearing surface 4c is equal to the thrust bearing surface 2b.
Even if the diameter of the raceway groove 2a is smaller than that of the raceway groove 2a, the rolling contact can be made similarly.

Between the raceway groove 2a on the thrust receiving surface 2b and the raceway groove 4a on the thrust bearing surface 4c, a plurality of balls 1, for example, three or more are arranged. The cage 6 is the thrust receiving surface 2
b between the thrust bearing surface 4c and the thrust bearing surface 4c to hold the balls 1 so that the distance between the balls 1 is equal, and the distance between the thrust receiving surface 2b and the thrust bearing surface 4c is kept constant by the balls 1. I have to.

The retainer 6 is made of, for example, synthetic resin or brass which is softer than the ball 1, the shaft 2, and the thrust plate 3. However, a full ball thrust ball bearing without the retainer 6 can also be used.

Further, the thrust receiving member 4 is press-fitted and attached to one end of the sleeve 5, and the lid 7 is placed on the upper surface of the thrust receiving member 4, and is fixed by the bolt 8 as a fixing member. 7 is fixed to the sleeve 5. Thus, the housing 3 of the bearing device of the present invention is configured.

However, there is no problem even if the thrust receiving member 4 and the lid 7 are integrated. In the embodiment of the present invention, the thrust receiving member 4 and the lid 7 are separate parts, but the fit between the inner diameter surface of the sleeve 5 and the thrust receiving member 4 is the thrust receiving surface 2b.
This is important for making the raceway groove 2a of the thrust bearing surface 4c concentric with the raceway groove 4a. That is, it is preferable that the axis 4b of the thrust receiving member coincides with the axis 5a of the sleeve. Although not shown, the inner diameter surface of the sleeve 5 has two cylindrical radial bearing surfaces 5b separated in the axial direction.
The shaft 2 fitted to the sleeve 5 has a radial bearing surface 5
b has a radial receiving surface 2c opposed to b.

Next, the operation of the bearing device of the present invention will be described. Electric current is applied to the stator of the motor (not shown) to generate a rotating magnetic field, thereby rotating the rotor of the motor. Thereby, the rotating member provided with the housing 3 is rotated.

Thus, the plurality of balls 1 provided between the thrust receiving member 4 and the shaft 2 are rotated while being in rolling contact. At this time, since the retainer 6 is provided, the interval between three or more balls is kept constant, and the rotation of the thrust receiving member 4 is performed smoothly. By using the thrust bearing as a thrust ball bearing in this way, the torque is small and the life of the bearing can be extended.

By the way, the continuation of such a rotation operation does not cause abrasion powder. By the rotation operation, between the thrust bearing surface 4c and the ball 1, the thrust receiving surface 2b
Since the ball and the ball 1 simply roll by rolling contact with or without lubricating oil, there is no problem of generation of wear powder due to sliding friction.

Therefore, when the housing 3 rotates, no abrasion powder is generated, so that the radial receiving surface 2c provided on the shaft 2 is provided.
Since the problem of mixing of wear powder that hinders the function as the dynamic pressure bearing does not occur in the bearing clearance between the bearing and the radial bearing surface 5b of the housing 3, the function as the dynamic pressure bearing can be smoothly exhibited.

That is, the radial receiving surface 2 provided on the shaft 2
The pressure of the lubricant or air in the bearing clearance between the radial receiving surface 2c and the radial bearing surface 5b of the housing 3 increases due to the pumping action of the herringbone-shaped groove 9 serving as the groove for generating the dynamic pressure of c, thereby increasing the sleeve. 5 is smoothly rotated while keeping a non-contact with the shaft 2 in the radial direction.

Since the bearing device of the present invention does not generate wear powder, the wear powder does not move to other parts of the device. In particular, the wear powder enters the dynamic pressure bearing device and stops the operation of the dynamic pressure bearing device. There is no such thing (prevention of locking phenomenon of dynamic pressure type bearing).

In the thrust ball bearing, the displacement of the ball due to the centrifugal force is small. Because the centrifugal force and the weight of the rotating member are balanced and the thrust ball bearing has a contact angle, the ball 1 can easily roll into contact with the raceway groove.
The ball 1 rolls stably in the raceway groove 2a provided in the thrust receiving surface 2b.

In the embodiment of the present invention, a structure in which the shaft 2 is fixed and the housing 3 is rotated has been described. However, the present invention is not limited to this, and the housing 3 is fixed and the shaft 2 is rotated.
Even with a structure for rotating a rotating member provided with, it is possible to prevent the generation of abrasion powder, which is the object of the present invention. Also, the groove for generating dynamic pressure is not limited to being provided on the radial bearing surface 2c, but may be provided on the radial bearing surface 5b, and may be provided on both the radial bearing surface 2c and the radial bearing surface 5b. it can.

[0042]

According to the first aspect of the present invention,
Because the rolling bearing receives the load in the thrust direction,
The torque applied to the bearing device can be greatly reduced. Accordingly, the life of the bearing is greatly improved.

Also, since it functions as a rolling bearing during the operation of the bearing, no sliding friction is generated and no wear powder is generated. Therefore, there is no possibility that the wear powder generated by the friction enters the radial bearing clearance and disables the operation of the bearing.

Further, when the contact angle of the thrust ball bearing is set to a predetermined value, the ball of the ball bearing is less likely to be displaced outward in the radial direction due to centrifugal force, thereby preventing the ball from rolling due to sliding contact and rolling contact. Can be rotated by.

[Brief description of the drawings]

FIG. 1 is a sectional view of a bearing device according to the present invention.

FIG. 2 is a partially enlarged view of a bearing device in consideration of a centrifugal force in the present invention.

FIG. 3 is a sectional view of a conventional hydrodynamic bearing device.

FIG. 4 is a sectional view of a conventional hydrodynamic bearing device.

FIG. 5 is a cross-sectional view showing a rotation state of a ball in a raceway groove.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 ball 2 shaft 2a shaft raceway groove 2b thrust receiving surface 2c radial receiving surface 3 housing 4 thrust receiving member 4a housing raceway groove 4b thrust plate shaft center 4c thrust bearing surface 5 sleeve 5a sleeve shaft center 5b radial bearing surface 6 Cage 7 Lid 8 Bolt 9 Herringbone groove

Claims (1)

[Claims] The housing has a sleeve and a thrust receiving member attached to one end of the sleeve, and an inner diameter surface of the sleeve has a cylindrical radial bearing surface at two places separated in an axial direction. The thrust receiving member has a thrust bearing surface, and the shaft fitted to the sleeve has a radial receiving surface facing the radial bearing surface and a thrust receiving surface facing the thrust bearing surface, and the radial bearing surface and the radial receiving surface. A bearing device provided with a groove for generating dynamic pressure in at least one of the above, wherein a plurality of balls are arranged between a raceway groove provided on a thrust receiving surface and a raceway provided on a thrust bearing surface.