Suspension thrust bearing unit

Abstract

Suspension Thrust Bearing Unit The invention relates to a suspension thrust bearing unit (1) for use in an automotive suspension assembly, comprising a bearing (5) having an upper ring (50) mounted inside an upper annular cover (3), a lower ring (51) mounted inside a lower annular cover (4), and at least one row of rolling elements (5) positioned between raceways defined by the lower ring (51) and the upper ring (50). The lower annular cover (4) includes at least one circumferential annular groove (60; 64), and the upper cover (3) includes an annular skirt (32), forming a sinuous chamber that defines labyrinth sealing means (6). According to the invention, said groove (60; 64) has a plurality of ribs (65; 66). Figure 2

Description

Title of the invention: Suspension thrust bearing unit Technical field of the invention

[0001] The present invention relates to the field of suspension bump stop bearing units, in particular of the MacPherson type. Such a suspension bump stop bearing unit equips a suspension assembly intended for use in a motor vehicle. Prior art

[0002] Generally, a motor vehicle suspension system comprises a suspension assembly supporting a vehicle axle and wheel. A suspension bump stop bearing unit is disposed in an upper portion of said suspension assembly, opposite the wheel and the ground, and between a suspension spring and an upper support block attached to the vehicle body.

[0003] The suspension stop bearing unit comprises at least one roller bearing.

[0004] The suspension thrust bearing unit allows the transmission of axial forces between the spring and the vehicle body and, at the same time, allows relative angular movement between the spring, which is mobile in rotation, and the fixed support block attached to the body.

[0005] To this end, the spring is supported by a spring seat provided on said suspension thrust bearing unit. More specifically, the suspension thrust bearing comprises a lower support surface resting on the end coils of the spring. Said spring support surface includes a radial surface to support an axial force. The spring support surface may also include a tubular axial surface to support radial deformations and ensure the centering of the spring.

[0006] The suspension thrust bearing unit is used in environments subject to constant pollution, particularly from dust, particles, and water. EP 1 000 781, US 6 186 507, and WO 07 / 037308 are examples that disclose suspension thrust bearing units equipped with sealing means to prevent any ingress of pollution into said units. These sealing means include contact lips. However, such sealing means are not entirely satisfactory because they create friction between the two parts of the units in relative rotation.

[0007] It is also known from WO 2010 / 063305 or JP 2006 322505 to provide a labyrinth seal without any contact portions between parts in relative rotation. Friction is reduced, but the sealing function must be optimized, particularly against heavy contamination, especially from a water jet. Summary of the invention

[0008] The objective of the invention is to provide a suspension thrust bearing unit with an improved labyrinth seal exhibiting optimized sealing performance while limiting rotational friction, and which is easy and inexpensive to manufacture.

[0009] To this end, the invention relates to a suspension bump stop bearing unit for use in an automotive suspension assembly. The suspension bump stop bearing unit comprises a bearing having an upper ring mounted inside an upper annular cover, a lower ring mounted inside a lower annular cover, and at least one row of rolling elements positioned between raceways defined by the upper and lower rings. The upper and lower annular covers are provided with sealing means to prevent contamination from entering the unit.

[0010] The lower annular cover comprises at least one circumferential annular groove located between a first sealing flange and a second sealing flange extending radially outward from said lower cover. The upper annular cover comprises an outer annular skirt extending axially from said upper cover toward the lower cover, at least one of the sealing flanges of the lower cover being radially surrounded by said skirt. Said groove, flanges, and skirt form a sinuous chamber defining labyrinth sealing means.

[0011] According to the invention, said annular circumferential groove is provided with a plurality of ribs. Said ribs are circumferentially spaced inside said groove. Said ribs extend radially outwards from the lower cover, are axially delimited between the first and second sealing gasket flanges, and are at least partially surrounded by the skirt.

[0012] Thanks to the invention, the interior of the suspension bump stop bearing unit is made sealed, that is to say, protected against the entry of dust, particles, and water from the outside. Radial flanges form physical barriers against water jets coming substantially axially or obliquely from the lower part of the vehicle towards said suspension bump stop bearing unit. The use of a plurality of radial flanges makes it possible to successively block the ingress of contaminants that manage to pass through the preceding flanges. An axial skirt of the upper cover surrounds said flanges and provides protection against radial projections of contaminants. The labyrinth sealing means of the invention They ensure improved water tightness in the axial, radial, and oblique directions. Successive sealing methods allow the amount of pollution to be reduced one after the other.

[0013] Furthermore, the plurality of ribs helps to interrupt the flow of contaminants within the labyrinth seal. More specifically, the ribs form axial walls that are circumferentially spaced inside the groove, while the flanges form radial walls. The flanges prevent contaminants from entering the groove, and the ribs interrupt the flow of contaminants within the groove. The effectiveness of the labyrinth seal is thus greatly improved.

[0014] The sealing function is designed without any contact element between the lower and upper covers in relative rotation so as to reduce friction.

[0015] The lower and upper rings of the bearing define an internal space in which rolling elements are arranged. The lower and upper rings are mounted inside the lower and upper covers of the unit, respectively, with a serpentine chamber defined between said covers. This serpentine chamber extends from the internal space within the bearing. This arrangement allows lubricant, such as a lubricating grease, to be added to the internal space after the unit has been mounted.

[0016] According to other aspects of the invention which are advantageous but not necessary, such a suspension thrust bearing unit may include one or more of the following features: - the inner and outer rings are made of a stamped metal sheet. - The upper and lower covers are made of a rigid plastic material, for example polyamide, possibly reinforced with glass fibers. - The upper and / or lower covers may include a stiffening insert. - The bearing consists of a rolling bearing, the inner and outer rings defining an annular rolling chamber between them and at least one row of rolling elements being arranged inside said rolling chamber. - The rolling elements are balls. - The lower annular hood includes a damping device dedicated to forming a seat for a suspension spring. - The lower annular portion includes an axial hub and the first flange extends radially outwards from said hub. The damping device includes a portion covering a lower radial surface of said first radial collar, said damping device being dedicated to forming a seat for a suspension spring. The damping device includes a portion covering an external cylindrical surface of the hub, said portion of the damping device being dedicated to supporting a radial load from a suspension spring. The damping device includes a radial collar that projects radially outwards beyond the first collar of the lower annular hood. The damping device consists of an elastic material, such as a rubber, a thermoplastic elastomer (TPE), in particular a thermoplastic polyurethane (TPU), a melt-processable elastomer (MPE) or a cellular polyurethane. The first sealing collar extends radially beyond the second sealing collar of the lower annular cover. The axial skirt of the upper annular cover radially surrounds the second sealing flange of the lower annular cover and is directed axially towards the first flange of the lower annular cover. The lower hood comprises a plurality of annular circumferential grooves, each defined between the upper and lower sealing gasket flanges. The lower annular hood includes a third collar extending radially outwards from said hood, a circumferential annular groove being defined between the second and third sealing collars, and said third collar being surrounded by the axial skirt of the upper annular hood. The second sealing collar extends radially beyond the third sealing collar of the lower annular cover. Each of the annular circumferential grooves has circumferentially spaced ribs, said ribs extending radially outwards from the lower cover, being axially delimited between the sealing collars which define the corresponding outer circumferential groove, and being at least partially surrounded by the skirt. The upper annular hood includes a second axial skirt which extends axially from said hood towards the second collar of the lower annular hood, said second axial skirt radially surrounding the third collar of the lower annular hood, said second axial skirt being radially surrounded by the first axial skirt of the upper annular hood. - The ribs are spaced circumferentially at equidistant intervals. - The ribs of the different annular circumferential grooves are aligned circumferentially with respect to each other. Brief description of the figures

[0017] The invention will now be explained with reference to the accompanying figures, by way of illustration, without restricting the scope of the invention. In the accompanying figures: - [Fig.1] is a top view of a suspension thrust bearing unit; - [Fig.2] is a perspective view of a lower hood for the unit in [Fig.1]; - [Fig. 3] is a first half-view in axial section of the unit of [Fig. 2] according to the invention; and - [Fig.4] is a second half-view in axial section of the unit of [Fig.2] according to the invention. Detailed description of the invention

[0018] A suspension strut bearing unit 1 having a central axis XI is mounted between a helical suspension spring (not shown) and a support block (not shown) connected to the chassis of a motor vehicle. Such a suspension strut bearing unit 1 can be used, for example, in a MacPherson strut assembly for automobiles.

[0019] Hereafter, the adjectives "axial" and "radial" are defined with respect to the central axis XI of the annular thrust bearing 1.

[0020] The suspension stop bearing unit 1 comprises an upper cover 3, a lower cover 4 and a single bearing 5. These three components 3, 4 and 5 are generally circular in shape around the central axis XL

[0021] The upper cover 3 consists of a single piece made of a synthetic plastic material, for example polyamide, optionally reinforced with glass fibers. The upper cover 3 has an upper radial portion 30, an inner annular skirt 31 of relatively small diameter extending towards the lower side of the suspension thrust bearing unit 1, and an outer annular skirt 32 of relatively large diameter extending towards the lower side of the suspension thrust bearing unit 1.

[0022] The upper cover 3 is dedicated to attachment to a support block (not shown) of the motor vehicle chassis.

[0023] The bearing 5 comprises an inner bearing ring 50 made of stamped sheet metal, an outer bearing ring 51 also made of stamped sheet metal, a row of rolling elements 52, here balls, and a cage 53 for maintaining a regular circumferential spacing between the rolling elements 52. The rolling elements 52 are arranged between raceways formed by toroidal portions of the inner bearing ring 50 and the outer bearing ring 51. As an alternative not shown, the rolling elements may be rollers.

[0024] The bearing 5 is located radially in its entirety between the inner skirt 31 and the outer skirt 32 of the upper cover 3. The inner bearing ring 50 is fitted inside an inner toroidal portion of the upper cover 3. The outer bearing ring 51 is fitted on an outer toroidal portion of the lower cover 4.

[0025] Said lower cover 4 includes a hub 41 defining an inner bore 42. The inner skirt 31 defines an inner bore 33 for the suspension stop bearing unit 1, an elongated shock absorber rod (not shown) being mounted in the bores 33, 42. The inner skirt 31 of the upper cover 3 includes a plurality of outwardly projecting fasteners 34 directed towards the hub 41 of the lower cover 4. Said lower cover includes an inwardly projecting fastener 44 directed towards said skirt 31. The fasteners 34 extend over a narrow angle, while the fastener 44 is annular. The fixing elements 34, 44 cooperate to ensure axial assembly of the upper and lower covers 3, 4. The fixing elements 34 and 44 each include a frustoconical surface to facilitate the assembly of the covers 3,4.

[0026] The lower hood 4 further includes an outwardly projecting radial collar 43 extending from the hub 41 outwards from the suspension stop bearing unit 1.

[0027] The toroidal outer portion supporting the outer bearing ring 51 of the bearing housing 51 is located on a superior surface of said radial flange 43.

[0028] The hub 41 of the lower hood 4 supports a radial load and shocks from the suspension spring, and also helps to dampen vibrations.

[0029] The lower hood 4 and the upper hood 3 further include sealing means 6 to prevent the entry of pollution into the internal space defined between said hoods 3, 4 and between the rings 50, 51 of the bearing 5.

[0030] According to the invention, the sealing means 6 consist of a labyrinth seal designed as follows.

[0031] The lower annular cover 4 includes a first annular circumferential groove 60 situated between a first sealing flange 61 and a second sealing flange 62, which extend radially outwards from said lower cover 4. More specifically, the sealing flanges 61 and 62 are annular along a parallel radial extension. The first sealing flange is a radial outward extension of the radial flange 43 of the lower cover 4. The second sealing flange 62 is axially offset relative to said first sealing flange 61 in the direction of the upper cover 3, thus defining the outer circumferential groove 60.

[0032] Advantageously, the first collar 61 extends radially beyond the second collar 62 of the lower annular cover 4.

[0033] The upper annular cover 3 includes the outer annular skirt 32 which extends axially from said upper cover 3 towards the lower cover 4. The second flange 62 of the lower cover 4 is radially surrounded by said skirt 32. In the present embodiment, the skirt 32 is directed towards the cover flange 43, the end of the skirt 32 being radially oriented towards the first sealing flange 61, and axially oriented towards the second sealing flange 62. Said groove 60, flanges 61 and 62 and skirt 32 form a sinuous chamber defining labyrinth sealing means 6.

[0034] As an unrepresented variant, the skirt 32 can radially surround said first collar 61.

[0035] The first radial sealing flange 61 forms a first axial stop against contamination, in particular to block axial or oblique jets of water or dust. The second flange 62 forms a second axial stop against contamination, in particular to block residual contamination not blocked by the first flange 61. The groove 60 directs the residual contamination from the second flange to the first flange. The skirt 32 forms a radial stop against contamination. The skirt 32 also redirects contamination blocked by the second flange 62 to the outside of the unit 1. Gaps between the first flange 61 and the skirt 32, and between the second flange 62 and the skirt 71, are reduced so as to limit the inlet dimension between the lower and upper covers for contamination but without any contact. Rotational friction is prevented between the hoods 3, 4 in relative rotation by the bearing 5.

[0036] Advantageously, the lower annular cover 4 includes a third sealing collar 63 which extends radially outwards from said cover 4. The third sealing collar 63 is annular along a radial extension parallel to the first and second collars 61, 62. The third sealing collar 63 is axially offset relative to said second sealing collar 62 towards the upper cover 3, thus defining a second external circumferential groove 64.

[0037] Said third collar 63 is surrounded by the axial skirt 32 of the upper annular cover 3.

[0038] Advantageously, the second collar 62 extends radially beyond the third collar 63 of the lower annular cover 4.

[0039] Advantageously, the upper annular cover 3 comprises a second axial skirt 35 which extends axially from said cover 3 towards the second flange 62 of the lower annular cover 4. Said second axial skirt 35 radially surrounds the third flange 63 of the lower annular cover 4, said second axial skirt 35 being radially surrounded by the first axial skirt 31 of the upper annular cover 3. An annular groove 36 is defined between said first and second skirts 31, 35 in the annular cover 3.

[0040] The third radial sealing flange 63 forms a third axial stop against contamination, in particular to block residual contamination not blocked by the first and second sealing flanges 61, 62. The groove 64 directs the residual contamination from the second flange to the third flange. The skirt 35 redirects the contamination blocked by the third flange 63 outwards from the unit 1. The groove 36 blocks the redirected contamination that passes through the second flange 72. Gaps between the second flange 62 and the skirt 35, and between the third flange 63 and the skirt 35, are reduced so as to further limit the inlet dimension between the lower and upper covers for contamination, but without any contact. This design forms a multi-level labyrinth seal for the unit.

[0041] According to the invention, the first and second annular circumferential grooves 60, 64 are both provided with a plurality of ribs 65, 66, respectively.

[0042] The first annular circumferential groove 60 has a first series of ribs 65. The ribs 65 are equidistant circumferentially spaced inside the groove 60. The ribs 65 extend radially outwards from the lower cover 4, and are axially delimited between the first sealing gasket collar 61 and the second sealing gasket collar 62.

[0043] The second annular circumferential groove 64 has a second set of ribs 66. The ribs 66 are equidistant circumferentially spaced inside the groove 64. The ribs 66 extend radially outwards from the lower cover 4, and are axially delimited between the second sealing flange 62 and the third sealing flange 63.

[0044] In the illustrated example, the ribs 65, 66 of the various annular circumferential grooves 60, 64 are aligned circumferentially with respect to each other.

[0045] As an alternative embodiment, only one of the two grooves 60, 64 is provided with a series of ribs. According to another embodiment, the lower cover 4 may comprise more than two external circumferential annular grooves, each of them being provided with a series of ribs.

[0046] The plurality of ribs 65, 66 interrupts the flow of contaminants into the labyrinth seal 6. More specifically, the ribs 65, 66 form axial walls that are circumferentially spaced inside the grooves 60, 64, while the sealing flanges 61, 62, 63 form radial walls. The flanges 61, 62, 63 prevent contaminants from entering the grooves 60, 64, and the ribs 65, 66 interrupt the flow of contaminants within the grooves 60, 64. The effectiveness of the labyrinth seal 6 is thus greatly improved.

[0047] According to an embodiment not shown, the lower cover 4 may include a damping device made of an elastic material, such as rubber, a thermoplastic elastomer (TPE), in particular thermoplastic polyurethane (TPU), a melt-processable elastomer (MPE), or a cellular polyurethane, for example. The damping device may be located on the underside of the lower cover 4 so as to support and dampen the spring.

[0048] Representative, but not limiting, examples of the present invention have been described in detail above with reference to the accompanying drawings. This detailed description is intended merely to teach a person skilled in the art further details for implementing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be used separately or in conjunction with other features and teachings to provide an improved suspension thrust bearing unit.

[0049] Furthermore, various features of the representative examples described above, as well as the various independent and dependent claims, can be combined in ways not specifically and explicitly listed in order to provide additional useful embodiments of the present teachings.

Claims

Demands

1. Suspension thrust bearing unit (1) for use in an automotive suspension assembly, comprising a bearing (5) having an upper ring (50) mounted inside an upper annular cover (3), a lower ring (51) mounted inside a lower annular cover (4), and at least one row of rolling elements (5) positioned between raceways defined by the lower ring (51) and the upper ring (50), the lower annular cover (4) and the upper annular cover (3) being provided with sealing means (6) to prevent contamination from entering the unit (1), the lower annular cover (4) comprising at least one circumferential annular groove (60; 64) situated between a first sealing flange (61; 62) and a second sealing flange (62;63) extending radially outwards from said lower cover (4), the upper annular cover (3) comprising an outer annular skirt (32) extending axially from said upper cover (3) towards the lower cover (4), at least one of the flanges (62; 63) of the lower cover (4) being radially surrounded by said skirt (32), said groove (60; 64), flanges (61, 62; 63) and skirt (32) forming a sinuous chamber defining labyrinth sealing means (6), characterized in that said circumferential annular groove (60; 64) is provided with a plurality of ribs (65; 66), said ribs (65; 66) being such that they are circumferentially spaced inside said groove (60; 64), and that they extend radially outwards from the lower cover (4), that they are axially delimited between the first and second sealing joint collars (61, 62;63), and that they are at least partially surrounded radially by the skirt (32).;

2. Unit according to claim 1, wherein the ribs (65; 66) are circumferentially spaced equidistantly.

3. Unit according to any one of the preceding claims, wherein the first collar (61) extends radially beyond the second collar (62) of the lower annular cover (4).

4. Unit according to claim 3, wherein the axial skirt (32) of the upper annular hood (3) radially surrounds the second collar (62) of the lower annular cover (4) and is directed axially towards the first collar (61) of the lower annular cover (4).

5. Unit according to any one of the preceding claims, wherein the lower annular cap (4) comprises a third collar (63) extending radially outwards from said cap (4), a circumferential annular groove (64) being defined between the second collar (62) and the third collar (63), and said third collar (63) being surrounded by the axial skirt (32, 35) of the upper annular cap (4).

6. Unit according to claim 5, wherein the second collar (62) extends radially beyond the third collar (63) of the lower annular cover (4).

7. Unit according to claim 6, wherein the upper annular hood (3) comprises a second axial skirt (35) which extends axially from said hood (3) towards the second flange (62) of the lower annular hood (4), said second axial skirt (35) radially surrounding the third flange (63) of the lower annular hood (4), said second axial skirt (35) being radially surrounded by the first axial skirt (31) of the upper annular hood (4).

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