Strut bearing

This disclosure provides a strut bearing for MacPherson strut suspensions including a cap, a guide ring, and a bearing arrangement located between the cap and the guide ring. The cap comprises a first hook on an inner side in a radial direction of the strut bearing and a third hook on an outer side in the radial direction, and the guide ring comprises a second hook on the inner side engaged with the first hook and a fourth hook on the outer side engaged with the third hook; the first and second hooks form an inner snap connection extending circumferentially, and the third and fourth hooks form an outer snap connection extending circumferentially.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase of PCT Appln. No. PCT/CN2017/117575 filed Dec. 20, 2017, the entire disclosure of which is incorporated by reference herein.

TECHNICAL FIELD

This disclosure relates to a strut bearing for MacPherson strut suspensions.

BACKGROUND

As a strut bearing for MacPherson strut suspensions, a typical thrust ball bearing consisting of a cap, a guide ring, a cage, an upper washer, a lower washer and a set of balls is known. The thrust ball bearing normally has a seal outside in a radial direction and a snap connection between the cap and the guide ring inside as disclosed in CN105705822A (or WO2015/067251A1) and DE102012215912A1, which are incorporated herein by reference for all purposes.

In the last few years, the requirement of the pull apart force has been increased step by step. For this reason the risk of failing to fulfill the pull apart test and the risk of getting a loose connection under a large working load are increased. The structure of single snap connection is functionally limited.

As shown inFIG. 1A, in a nominal position without any displacements, an axial line X1of the cap100and an axial line X2of the guide ring200coincide with each other, a first hook101of the cap100on one side of the axial line X1and a second hook201of the guide ring200on the one side have a good connection, and the first hook101′ of the cap100on the other side of the axial line X1and the second hook201′ of the guide ring200on the other side also have a good connection.

FIG. 1Ais a kind of outer side snap connection. It should be understood that the first hook101and101′ is one circumferential lower hook of the cap100, and the reference numbers101and101′ is only used to distinguish different parts of the same circumferential hook of the cap100, and that the second hook201and201′ is one circumferential upper hook of the guide ring200, and the reference numbers201and201′ is only used to distinguish different parts of the same circumferential hook of the guide ring200.

FIG. 1Bshows that there is a displacement in the radial direction R between the cap100and the guide ring200, to be specific, the guide ring200has moved with respect to the cap100in a direction RI. In such a case, the first hook101′ of the cap100and the second hook201′ of the guide ring200has a good connection, but the connection between the first hook101of the cap100and the second hook201of the guide ring200is poor and there is a risk of loose connection during operation of the thrust ball bearing. Loose connection may also occur when the cap100and/or the guide ring200are tilted with respect to an axial direction A.

In addition, unexpected cracks and failures may happen for balls getting out of the cage and raceways when loose connection occurs.

SUMMARY

In view of the above condition, this disclosure provides a strut bearing for MacPherson strut suspensions.

This disclosure provides a strut bearing for MacPherson strut suspensions including a cap, a guide ring, and a bearing arrangement located between the cap and the guide ring. The cap may comprise an inner lower hook on an inner side in a radial direction of the strut bearing and an outer lower hook on an outer side in the radial direction, and the guide ring may comprise an inner upper hook on the inner side engaged with the inner lower hook and an outer upper hook on the outer side engaged with the outer lower hook. The inner lower and inner upper hooks may form an inner snap connection extending circumferentially, and the outer lower and outer upper hooks may form an outer snap connection extending circumferentially.

Further features of this disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

DETAILED DESCRIPTION

The following describes in detail preferable exemplary embodiments of this disclosure with reference to the attached drawings.

As shown inFIG. 2, a first embodiment provides a thrust ball bearing1. The thrust ball bearing1has substantially a rotationally symmetric structure, andFIG. 2shows only part of its cross section along an axial direction A of the thrust ball bearing1. The thrust ball bearing1comprises a cap10, a guide ring60and a bearing arrangement. The bearing arrangement may comprise an upper washer20, a set of balls30, a cage40, and a lower washer50.

The cap10may be mounted on a top mount (not shown) by fit ribs11on the cap10. The cap10may be made of a combination of two materials, that is, a hard part10A made of hard polymer and a soft part10B made of soft polymer. Both the upper washer20and the lower washer50may be made of steel and angularly contact with the balls30. The upper washer20is seated in a washer seat12by interference fit with washer fit ribs13on the hard part10A. The balls30which may be made of steel are seated in pockets of the cage40. The cage40which may be made of hard polymer is suspending between the upper washer20and the lower washer50. The lower washer50is seated in a washer seat61by interference fit with washer fit ribs62on the guide ring60which may be made of hard polymer.

An inner snap connection in a radial direction R of the thrust ball bearing1is constituted by an inner lower hook14formed on the soft part10B of the cap10and an inner upper hook63formed on the guide ring60. An outer snap connection in the radial direction R is constituted by an outer lower hook19formed on the hard part10A of the cap10and an outer upper hook66formed on the guide ring60. The inner lower hook14and the outer lower hook19each have engaging surfaces facing one side (the upper side inFIG. 2) in the axial direction A, and the inner upper hook63and the outer upper hook66each have engaging surfaces facing the other side (the lower side inFIG. 2) in the axial direction A.

The soft part10B, in the cross section inFIG. 2, may have approximately an inverted U-shape, which has a first leg10B1, a second leg10B2and a bottom10B3. It should be understood that, along the circumferential direction of the thrust ball bearing1, openings may form on the soft part10B, and the hard part10A may occupy such openings to enhance adhesion between the soft part10B and the hard part10A. The inner lower hook14may be formed on the distal end of the first leg10B1. One or more sealing lips16,17may be formed on the second leg10B2. The inner sealing lip16in the radial direction R contacts with a sealing bevel64on the guide ring60. The outer sealing lip17in the radial direction R does not contact with, but is very close to a splash guard65on the guide ring60. The sealing lips16,17, the sealing bevel64, the splash guard65, the outer lower hook19and the outer upper hook66can form a labyrinth seal.

The hard part10A, in the cross section inFIG. 2, may also have approximately an inverted U-shape, which has a first leg10A1, a second leg10A2and a bottom10A3. The first leg10A1, the bottom10A3and a base part of the second leg10A2are bonded to a base part of the first leg10B1, the bottom10B3, and a base part of the second leg10B2of the soft part10B, respectively. The outer lower hook19may be formed on the distal end of the second leg10A2.

The guide ring60, in the cross section inFIG. 2, may have approximately an inverted L-shape, which has a first arm67extending substantially in the axial direction A and a second arm68extending substantially in the radial direction R. The inner upper hook63and the outer upper hook66are formed on the base and distal ends of the second arm68, respectively.

The washer seat12is formed at a corner between the first leg10A1and the bottom10A3, and the washer seat61is formed at a corner on the middle part of the second arm68. The washer seats12and61face each other diagonally, in a direction tilted with respect to the radial direction R and the axial direction A. The balls30therefore are supported by the upper washer20and the lower washer50in the direction tilted with respect to the radial direction R and the axial direction A.

The sealing bevel64and the splash guard65may be formed on the part of the second arm68near the outer upper hook66.

The hard polymer may be a plastic such as polyamide, and can also be reinforced by a fiber such as glass fiber. As examples, PA66-GF25 and PA66-GF35 can be used as the hard polymer. The soft polymer may be a thermoplastic elastomer or rubber, such as thermoplastic polyurethane (TPU) or nitrile butadiene rubber (NRB).

A second embodiment has a similar concept as that of the first embodiment and only the differences therebetween will be described hereinafter.

As shown inFIG. 3, in this second embodiment, the cap10is made of hard polymer and both of the inner lower hook14and the outer lower hook19are made of the hard polymer.

In this embodiment no soft part is incorporated in the cap10or the guide ring60. A second sealing finger18is formed on the cap10near the outer lower hook19and projects towards the guide ring60. A first sealing finger691and a third sealing finger692are formed on the guide ring60near the outer upper hook66and projects towards the cap10. Preferably, the second sealing finger18points to a valley between the first sealing finger691and the third sealing finger692, therefore a labyrinth seal is formed near the outer snap connection.

The operation of the thrust ball bearing1regarding the snap connections will be described hereinafter.

As shown inFIG. 4A, in a nominal position without any displacements, an axial line X1of the cap10and an axial line X2of the guide ring60coincide with each other, the inner lower hook14,14′ of the cap10and the inner upper hook63,63′ of the guide ring60have a good connection, and the outer lower hook19,19′ of the cap10and the outer upper hook66,66′ of the guide ring60also have a good connection.

It should be understood that only the cap10and the guide ring60are conceptually shown inFIGS. 4A and 4B, and the bearing arrangement is omitted.

It should be understood that the inner lower hook14and14′ is one circumferential hook of the cap10, and the reference numbers14and14′ is only used to distinguish different parts of the same circumferential hook of the cap10, that the inner upper hook63and63′ is one circumferential hook of the guide ring60, and the reference numbers63and63′ is only used to distinguish different parts of the same circumferential hook of the guide ring60. The reference numbers19and19′, and the reference numbers66and66′ are the same.

FIG. 4Bshows that there is a displacement in the radial direction R between the cap10and the guide ring60, to be specific, the guide ring60has moved with respect to the cap10in a direction R1. In such a case, the outer snap connection on one side of the axial line X1between the outer lower hook19′ of the cap10and the outer upper hook66′ of the guide ring60is poor, as well as the inner snap connection on the other side of the axial line X1between the inner lower hook14of the cap10and the inner upper hook63of the guide ring60. However, the inner snap connection on the one side between the inner lower hook14′ of the cap10and the inner upper hook63′ of the guide ring60is in good condition, as well as the outer snap connection on the other side between the outer lower hook19of the cap10and the outer upper hook66of the guide ring60. In other words, good snap connections are obtained in both sides of the axial lines X1and X2, such that the cap10and the guide ring60can not be separated from each other in the axial direction A.

The effects of this disclosure are described hereinafter.

1. The thrust ball bearing1can be used for MacPherson strut suspensions as a strut bearing. Double snap connections increase the pull apart force by more overlapping area, and thus make the bearing to be more stable and have less risk of failure than the traditional strut bearing.

2. Double snap connections arranged on both the inner side and the outer side decrease the risk of loose connection under a radial displacement or tilting during operation, and thus make the bearing to be more stable and have longer lifetime than the traditional strut bearing.

3. The outer snap connection reinforces the labyrinth sealing function and protects the sealing lips, because less water or dust will come onto the sealing lips.

While this disclosure has been described with reference to exemplary embodiments, it is to be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications and equivalent structures and functions such as the followings.

(1) For example, the double snap connections can also be used in strut bearings having other structures. KR20170086371A and KR20170103570A, for example, disclose strut bearing having other structures, which are incorporated herein by reference for all purposes.

(2) The strut bearing of this disclosure is not limited to the thrust ball bearing, it can also be, for example, thrust needle roller bearings, sliding bearings or rolling bearings. Therefore, other types of rolling element or a sliding bearing piece may be used instead of the balls30. CN103314224A (or US2013270790 A1) and CN104936806A (or US2015367698 A1), for example, disclose sliding bearings, and CN103423312A (or US2013313766 A1), for example, discloses a rolling bearing, which are incorporated herein by reference for all purposes.

(3) In the first embodiment, the sealing lips16,17and the inner lower hook14are made of soft polymer, in such a case a good sealing effect can be obtained. In the second embodiment, the two snap connections are both made of the hard polymer and therefore a larger pull apart force can be withstood.

However, this disclosure is not limited to such conditions. Both the snap connections can be made of hard polymer while the sealing lips are made of soft polymer such as rubber.

The sealing lips can also be formed or provided on the guide ring60.

LIST OF REFERENCE NUMBERS

100cap101,101′ first hook of the cap200guide ring201,201′ second hook of the guide ringX1axial line of the capX2axial line of the guide ringA axial directionR radial direction1thrust ball bearing10cap10A hard part10A1first leg of the hard part10A2second leg of the hard part10A3bottom of the hard part10B soft part10B1first leg of the soft part10B2second leg of the soft part10B3bottom of the soft part11fit rib12washer seat13fit rib14,14′ (first) inner lower hook16inner sealing lip17outer sealing lip18second sealing finger19,19′ (third) outer lower hook20upper washer30ball40cage50lower washer60guide ring61washer seat62fit rib63,63′ (second) inner upper hook64sealing bevel65splash guard66,66′ (fourth) outer upper hook67first arm68second arm691first sealing finger692third sealing finger