JP2007010097A - Bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost bearing unit surely preventing a lubricant from leaking and a foreign matter from entering over a long time. <P>SOLUTION: The bearing unit comprises: a stationary ring 2 fixed to a vehicle body side and normally kept in a non-rotating state; a rotating ring 4 that is connected to a wheel side and rotates together with a wheel; and a plurality of rolling bodies 6, 8 rollably installed between the stationary ring and the rotating ring in a plurality of rows. Sealing members 10, 20 for sealing the inside of a bearing are arranged between the stationary ring and the rotating ring at both sides of the bearing. In this case, a solid-state lubricant among the lubricants sealed between and among the stationary ring, the rotating ring and the sealing member is sealed between at least the rolling body and the sealing member, and a liquid-state or a semi-solid state lubricant is sealed between the rows of the rolling bodies that form the plurality of rows. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing unit that rotatably supports a wheel (for example, a disc wheel) of an automobile with respect to a vehicle body (for example, a suspension device (suspension)).

  Conventionally, this type of bearing unit includes, for example, a stationary wheel fixed to a vehicle body side (for example, a suspension device (suspension)) and maintained in a non-rotating state, and a wheel side (for example, as shown in Patent Document 1, for example). A rotating wheel connected to the disk wheel and rotating together with the wheel, and a seal member for sealing the inside of the bearing is provided between the stationary wheel and the rotating wheel. In addition, a lubricant is sealed between the stationary wheel, the rotating wheel, and the seal member, which reduces friction and wear inside the bearing, prevents seizure, and extends the life of flaking due to rolling fatigue. The temperature rise of the bearing is suppressed.

By the way, in the lubrication of bearings, for example, semi-solid and liquid lubricants such as grease and oil, and solid lubricants such as phosphate and oxide, or hydroxide and sulfide are generally used. However, in grease lubrication and oil lubrication, it is difficult to reliably prevent leakage of the lubricant to the outside of the bearing and entry of foreign matter (for example, water and dust) into the bearing for a long period of time. In addition, the solid lubricant is relatively expensive, and the manufacturing cost of the bearing unit increases depending on the amount enclosed in the bearing.
JP 7-317753 A

  Accordingly, an object of the present invention is to provide a low-cost bearing unit that reliably prevents the leakage of lubricant and the entry of foreign matter over a long period of time.

In order to achieve such an object, the present invention provides a stationary wheel that is fixed to the vehicle body side and is always kept in a non-rotating state, a rotating wheel that is connected to the wheel side and rotates together with the wheel, and a stationary wheel and a rotating wheel. And a plurality of rolling elements that are assembled to be freely rotatable in a plurality of rows between the wheels, and a seal member for sealing the inside of the bearing is provided between the stationary wheels and the rotating wheels on both sides of the bearing. Among the lubricants sealed between the stationary wheel, the rotating wheel, and the seal member, a solid lubricant is sealed at least between the rolling elements and the seal member. Yes.
In this case, a liquid or semi-solid lubricant is sealed between the rows of rolling elements forming a plurality of rows.

  According to the present invention, a low-cost bearing unit that reliably prevents the leakage of lubricant and the intrusion of foreign matters over a long period of time by enclosing a solid lubricant at least between the rolling elements and the seal member. Can be realized.

  Hereinafter, a bearing unit according to an embodiment of the present invention will be described with reference to the accompanying drawings. The wheel support bearing according to the present embodiment can be used for various vehicles such as automobiles and railway vehicles, but here, as an example, a bearing unit incorporated in a driving wheel or a driven wheel of the automobile will be described. To do.

  As shown in FIG. 1 (a), the bearing unit of the present embodiment includes a stationary wheel 2 that is fixed to the vehicle body and is always kept in a non-rotating state, and is provided inside the stationary wheel 2 and on the wheel side. A rotating wheel 4 which is connected and rotates together with the wheel, and a plurality of rolling elements 6 and 8 which are rotatably incorporated in a plurality of rows (for example, two rows) between the stationary wheel 2 and the rotating wheel 4; Seal members 10 and 20 are provided between the stationary wheel 2 and the rotating wheel 4 for sealing the inside of the bearing unit. The stationary wheel 2 has a hollow cylindrical shape and is disposed so as to cover the outer periphery of the rotating wheel 4. Moreover, although balls are illustrated in the drawings as the rolling elements 6 and 8, it goes without saying that rollers can be applied according to the configuration and type of the bearing unit.

  The stationary ring 2 is integrally formed with a fixing flange 2a protruding outward from the outer peripheral surface thereof, and a fixing bolt (not shown) is inserted into the fixing hole 2b of the fixing flange 2a, and this is connected to the vehicle body side. The stationary wheel 2 can be fixed to a suspension device (suspension) (not shown). The rotating wheel (inner ring) 4 is provided with a substantially cylindrical hub 12 that is connected to, for example, a disk wheel (not shown) of an automobile and rotates together. A hub flange 12a for connecting a disc portion (not shown) of a disc wheel is protruded from the hub 12 on one side in the axial direction thereof.

  The hub flange 12a extends outward (outward in the radial direction of the hub 12) beyond the stationary ring (outer ring) 2, and is arranged at predetermined intervals along the circumferential direction in the vicinity of the extended edge. A plurality of hub bolts 14 are provided. In this case, the plurality of hub bolts 14 are inserted into bolt holes (not shown) formed in the disc portion (disc wheel) and tightened with a hub nut (not shown), whereby the disc portion (disc wheel) is attached to the hub flange 12a. Can be positioned and fixed.

  Further, an annular inner ring structure 16 (a member constituting the rotating wheel 4 together with the hub 12) is fitted on the hub 12 on the other side in the axial direction. For example, the stationary wheel 2 and the rotating wheel 4 are fitted. With the plurality of rolling elements 6 and 8 held by the cage 18 between the inner ring component 16 and the stepped portion 12b formed on the hub 12, the other end portion 12c of the hub 12 is By caulking, the inner ring component 16 can be fixed to the other axial side of the hub 12.

  In this state, the two rows of rolling elements 6 and 8 make contact with the raceway surfaces (stationary raceway surface 2s and rotary raceway surface 4s) of the stationary wheel 2 and the rotating wheel 4 at a predetermined contact angle with each other. And it is assembled so that it can rotate. In this case, action lines L1 and L2 (see FIG. 1 (b)) connecting the two contact points are orthogonal to each raceway surface and pass through the centers of the rolling elements 6 and 8, and 1 on the center line of the bearing unit. Intersect at a point (point of action). This constitutes a rear combination (DB) bearing.

  In this configuration, the forces acting on the wheels of various automobiles are all transmitted from the disk wheel (disk portion) to the suspension device through the bearing unit, and at that time, the bearing unit has various loads (radial load, Axial load, moment load, etc.) are applied. However, since the bearing unit is a back-to-back (DB) bearing, high rigidity can be maintained against various loads (radial load, axial load, moment load, etc.).

  Further, the seal members 10 and 20 are provided on both sides (one side and the other side in the axial direction) of the bearing unit, respectively, and the enclosed lubricant (e.g., grease, oil) leaks to the outside of the bearing or foreign matter ( For example, water and dust) are prevented from entering the bearing. In the present embodiment, as an example of the seal member, the seal 10 is applied to one side in the axial direction of the hub 12, and the pack seal 20 is applied to the other side in the axial direction of the hub 12.

  The seal 10 is provided with one or a plurality of seal lips (not particularly denoted by reference numerals), and each seal lip is maintained in a state where it is always in sliding contact with the outer diameter surface of the hub 12. . On the other hand, the pack seal 20 is composed of a slinger 20a fitted on the inner ring component 16 and a seal body 20b fitted on the stationary ring 2. In this case, the seal body 20b is provided with one or a plurality of seal lips (not particularly denoted by reference numerals), and each seal lip is maintained in a state in which it is always in sliding contact with the slinger 20a.

  In such a bearing unit, various lubricants (for example, liquid lubricants) are provided between the stationary wheel 2, the rotating wheel 4 (inner ring component 16, hub 12), and the seal member (seal 10, pack seal 20). , Semi-solid lubricant, solid lubricant). In the present embodiment, as an example, as shown in FIG. 1B, the outer space region F1 (for example, a portion indicated by hatching) between the rolling elements 6 and 8 and the seal members 10 and 20 is fixed. Shaped lubricant is enclosed. Here, as the solid lubricant, for example, molybdenum disulfide, graphite, polytetrafluoroethylene (PTFE), soft metal (copper, metal, etc.) can be applied, but the solid oil of the trade name "Lube Guard" is applied. It is preferable to do. “Lube Guard” is a registered trademark of NSK Ltd.

  The product name “Lube Guard” is a mixture of a lubricating oil and a polyolefin resin having an affinity for the lubricating oil in a predetermined composition ratio, heated at a temperature equal to or higher than the melting point of the resin, plasticized, and then cooled and solidified. Solid lubricant made into a shape. In this case, as the lubricant, for example, poly α-olefin oil, mineral oil, phthalate oil, and the like can be applied. On the other hand, as the polyolefin resin, for example, polyethylene, polypropylene, polybutylene, polymethylpentene, and the like. It is possible to apply. The composition ratio of the “rubb guard” enclosed in the outer space region F1 (FIG. 1B) between the rolling elements 6 and 8 and the seal members 10 and 20 is 10 to 10. It is preferable to set 50% by weight and 90-50% by weight of the lubricant.

  According to such a “rubb guard”, the lubricating performance of the bearing unit can be maintained over a long period of time by the oil that exudes from the solid lubricant. Further, since it also has a dustproof effect, it is possible to reliably prevent foreign matters (for example, water and dust) from entering the inside of the bearing for a long period of time. Furthermore, after applying a special treatment to the bearing surface (for example, the surface where the stationary wheel 2 and the rotating wheel 4 face each other or the surface of the rolling elements 6 and 8), the solid lubricant is sealed (filled). The torque can be reduced when the bearing rotates.

  Thus, in a state where the “rubb guard” is sealed in the outer space region F1, the liquid space or semi-solid lubricant is sealed in the inner space region F2 between the two rows of rolling elements 6 and 8. It has become. In the present embodiment, as an example, a grease (not shown) that is a semi-solid lubricant is enclosed in the middle space region F2. In addition, the range designation | designated of each space area | region F1, F2 shown by FIG.1 (b) is an illustration to the last, and is not limited to this.

  For example, each of the rolling elements 6 and 8 is incorporated so as to be rotatable in contact with the raceway surfaces (stationary raceway surface 2s, rotation raceway surface 4s) of the stationary wheel 2 and the rotating wheel 4 at a predetermined contact angle with each other. At this time, the solid lubricant may settle in the space region between the action lines L1, L2 connecting the two contact points and the seal members 10, 20. In this case, the inside space region is defined between the two action lines L1 and L2, and the grease which is a semi-solid lubricant settles here.

  Grease has a thickener and base oil as main components. Calcium complex soap, barium complex soap), silica airgel, bentonite, polyurea or the like can be applied.

  As the base oil, for example, a mineral oil that is a naturally-occurring petroleum-based lubricating oil and a synthetic oil such as silicone oil or diester oil that are artificially produced are used. In this case, the viscosity of the base oil is adjusted according to the usage environment and purpose of the bearing unit. For example, if the purpose of use is high-speed rotation of the bearing in a low-temperature and low-load usage environment, a semi-solid lubricant (grease) containing a base oil with low viscosity is applied. If the purpose of use is a low-speed rotation of the bearing in the use environment, a semi-solid lubricant (grease) containing a base oil having a high viscosity may be applied.

As described above, according to the present embodiment, the solid lubricant (for example, lub guard) is sealed in the outer space region F1 between the rolling elements 6 and 8 and the seal members 10 and 20, so that the dust prevention of the solid lubricant is performed. The synergistic effect of the action and the seal members 10 and 20 makes it possible to reliably prevent the leakage of the lubricant to the outside of the bearing and the intrusion of the foreign matter to the inside of the bearing over a long period of time. In this case, since the solid lubricant does not mix with the semi-solid lubricant (grease) in the inner space region F2 during the rotation of the bearing, the lubricant leakage prevention effect and the foreign matter intrusion prevention effect can be maintained for a long time. Can be maintained.
Further, according to the present embodiment, it is only necessary to partially enclose a relatively expensive solid lubricant inside the bearing, so that the manufacturing cost of the bearing unit can be reduced.

  In the above-described embodiment, as a method of enclosing the solid lubricant (Lube Guard) and the semi-solid lubricant (grease) in the bearing, first, for example, the outer peripheral surface (rotating raceway surface) of the rotating wheel 4 (hub 12) is used. 4) (including 4 s) is prepared. Next, while the plurality of rolling elements 6 and 8 are held by the cage 18, the rolling elements 6 and 8 are assembled to the stationary raceway surface 2 s of the stationary wheel 2 and the seal 10 is fitted into the stationary wheel 2. And the stationary wheel 2 in which each rolling element 6,8, the retainer 18, and the seal | sticker 10 were assembled | attached in this way is set in a metal mold | die.

  At this time, on both sides of the rolling elements 6 and 8, mold molding spaces having the same shape as the outer space region F1 shown in FIG. 1B are configured, and in that state, lubricant and polyolefin are placed in each mold molding space. Filled with mixed material with resin. The solid lubricant “Lube Guard” can be sealed in each mold molding space by cooling after the resin is heated at a temperature equal to or higher than the melting point of the resin and then cooled.

  Subsequently, the stationary wheel 2 is removed from the mold together with the lub guard, and a semi-solid lubricant (grease) is sealed between the rolling elements 6 and 8 (inside space region F2), and then is removed from the hub 12 Fit. Then, the inner ring component 16 is externally fitted to the step portion 12b formed on the hub 12, the other end portion 12c of the hub 12 is crimped, and then the pack seal 20 is attached, whereby a solid lubricant ( Lub guard) and a bearing unit filled with semi-solid lubricant (grease) can be completed. FIG. 1B shows an example in which a solid lubricant (Lube Guard) is sealed in the shaded portion.

  As another method, for example, a mold having the same shape as the inner peripheral surface (stationary raceway surface 2s) of the stationary wheel 2 and the outer peripheral surface (rotational raceway surface 4s) of the rotating wheel 4 (hub 12) is used. prepare. Next, only the plurality of rolling elements 6 and 8 held by the cage 18 are set in the mold. At this time, on both sides of the rolling elements 6 and 8, mold molding spaces having the same shape as the outer space region F1 shown in FIG. 1B are configured, and in that state, lubricant and polyolefin are placed in each mold molding space. Filled with mixed material with resin. The solid lubricant “Lube Guard” can be sealed in each mold molding space by cooling after the resin is heated at a temperature equal to or higher than the melting point of the resin and then cooled.

Subsequently, the rolling elements 6 and 8 held by the retainer 18 together with the lub guard are removed from the mold, and the seal 10 is fitted into the stationary wheel 2, and then the rolling elements 6 and 8 together with the lub guard are fixed to the stationary wheel 2. Are assembled to the stationary track surface 2s. In this state, a semi-solid lubricant (grease) is sealed between the rolling elements 6 and 8 (inside space region F2), and then externally fitted to the hub 12. Then, the inner ring component 16 is externally fitted to the stepped portion 12b formed on the hub 12, the other end portion 12c of the hub 12 is crimped, and then the pack seal 20 is attached, whereby a solid lubricant ( Lub guard) and a bearing unit filled with semi-solid lubricant (grease) can be completed. Also in this case, the shaded portion of FIG. 1B can be assumed as an example of enclosing the solid lubricant (Lube Guard).
It should be noted that the sealing method as described above is merely an example, and it goes without saying that other methods may be used.

  In the above-described embodiment, a bearing unit in which grease that is a semi-solid lubricant is encapsulated in the inner space region F2 is assumed. However, the present invention is not limited to this, and the inner space region F2 is liquid. The lubricant (oil) may be enclosed. In this case, for example, refined mineral oil or synthetic oil may be applied as the lubricating oil. When oil is used as the lubricant, it is preferable to supply oil at a predetermined timing. As an oil supply method, an existing method (for example, jet lubrication, dripping lubrication, splash lubrication) can be appropriately selected.

(a) is sectional drawing which shows the structure of the bearing unit which concerns on one embodiment of this invention, (b) is a fragmentary sectional view which expands and shows the sealing state of a lubricant.

Explanation of symbols

2 Stationary wheel 4 Rotating wheel
6,8 rolling elements
10,20 Seal member 12 Hub 16 Inner ring component 18 Cage

Claims (2)

A stationary wheel that is fixed to the vehicle body side and is maintained in a non-rotating state at all times, a rotating wheel that is connected to the wheel side and rotates together with the wheel, and a stationary wheel and the rotating wheel are rotatably incorporated in a plurality of rows. A plurality of rolling elements, and a bearing unit provided with a seal member for sealing the inside of the bearing between the stationary ring and the rotating ring on both sides of the bearing,
A bearing unit in which a solid lubricant is sealed at least between a rolling element and a seal member among lubricants sealed between a stationary wheel, a rotating wheel, and a seal member. 2. The bearing unit according to claim 1, wherein a liquid or semi-solid lubricant is sealed between rows of rolling elements forming a plurality of rows.

Images