Suspension thrust bearing unit

Abstract

The invention relates to a suspension thrust bearing unit (1) for use in an automotive suspension assembly and comprising a bearing (5) having an upper ring (50) mounted inside an upper annular cap (3), a lower ring (51) mounted inside a lower annular cap (4), and at least one row of rolling elements (52) positioned between raceways defined by the lower ring (51) and the upper ring (50). The lower annular cap (4) comprises at least one annular circumferential groove (60; 64) and the upper cap (3) comprises an annular skirt (32) forming a tortuous chamber defining the labyrinth seal member (6). According to the invention, the groove (60; 64) is provided with a plurality of ribs (65; 66).

Description

Technical Field

[0001] This invention relates to the field of suspension thrust bearing units, and particularly to the field of MacPherson strut suspension thrust bearing units. Such suspension thrust bearing units are fitted into suspension assemblies used in motor vehicles. Background Technology

[0002] Typically, a motor vehicle suspension system includes a suspension assembly that supports the axles and the vehicle wheels. The suspension thrust bearing unit is located in the upper portion of the suspension assembly opposite the wheels and the ground, and is positioned between the suspension springs and the upper support block attached to the vehicle body.

[0003] The suspension thrust bearing unit includes at least one rolling bearing.

[0004] The suspension thrust bearing unit can transmit axial force between the spring and the vehicle body, while allowing relative angular movement between the rotatable spring and the fixed support block attached to the vehicle body.

[0005] For this purpose, the spring is supported by a spring seat mounted on the suspension thrust bearing unit. More precisely, the suspension thrust bearing includes a lower support surface resting on the end coil of the spring. The spring support surface includes a radial surface for supporting axial forces. The spring support surface may also include a tubular axial surface for supporting radial deformation and ensuring spring centering.

[0006] Suspension thrust bearing units are used in environments frequently exposed to contaminants, particularly dust, particles, and water. EP 1000 781, US 6 186 507, and WO 07 / 037308 disclose examples of suspension thrust bearing units that include a sealing element to prevent any contaminants from entering the unit. The sealing element includes a contact lip. However, this sealing element is not entirely satisfactory due to friction generated between the two components rotating relative to each other within the unit.

[0007] Labyrinth seals are also known from WO 2010 / 063305 or JP 2006 322505, but there are no contact points between the relatively rotating parts. Friction is reduced, but the sealing performance must be optimized, especially for severe contamination, particularly water jets. Summary of the Invention

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

[0009] Therefore, the present invention relates to a suspension thrust bearing unit for use in an automotive suspension assembly. The suspension thrust bearing unit includes a bearing having an upper ring mounted inside an upper annular cap, a lower ring mounted inside a lower annular cap, and at least one row of rolling elements positioned between raceways defined by the lower and upper rings. The lower and upper annular caps are provided with sealing members to prevent contaminants from entering the unit.

[0010] The lower annular cap includes at least one annular circumferential groove disposed between a first sealing flange (or flange) and a second sealing flange extending radially outward from the lower cap. The upper annular cap includes an annular outer skirt extending axially from the upper cap toward the lower cap, and at least one of the sealing flanges of the lower cap is radially surrounded by the skirt. The groove, the flange, and the skirt form a sinuous chamber defining a labyrinth seal component.

[0011] According to the present invention, the annular circumferential groove is provided with a plurality of ribs. The ribs are spaced apart circumferentially within the groove. The ribs extend radially outward from the lower cap, the ribs are axially defined between the first sealing flange and the second sealing flange, and the ribs are at least partially surrounded radially by the skirt.

[0012] Due to this invention, the interior of the suspension thrust bearing unit is sealed, preventing the ingress of dust, particles, and water from the outside. Radial flanges form a physical barrier against water jets flowing substantially axially or obliquely from the vehicle underside toward the suspension thrust bearing unit. The use of multiple radial flanges allows for the continuous blocking of contaminants that successfully pass through the front flange. An axial skirt of the upper cap surrounds the flanges and ensures prevention of radial projections of contaminants. The labyrinth seal of this invention ensures improved watertightness in the axial, radial, and oblique directions. The continuous sealing elements allow for a reduction in the amount of contamination following each seal.

[0013] Furthermore, multiple ribs allow for the interruption of contaminant flow into the labyrinth seal. More precisely, ribs are formed as circumferentially spaced axial walls within the groove, while flanges form radial walls. The flanges prevent contaminants from entering the groove, while the ribs allow for the disruption of contaminant dynamics within the groove. Thus, the labyrinth seal efficiency is significantly improved.

[0014] The sealing function is designed so that there are no contact elements between the relatively rotating lower and upper caps to reduce friction.

[0015] The lower and upper rings of the bearing define an internal space in which the rolling elements are disposed. The lower and upper rings are respectively mounted inside the lower and upper caps of the unit, defining a tortuous chamber between the caps. This tortuous chamber extends from the internal space of the bearing. This configuration allows lubricant (such as grease) to be added to the internal space after the unit is installed.

[0016] According to other advantageous but non-mandatory aspects of the invention, this suspension thrust bearing unit may incorporate one or more of the following features:

[0017] - The inner and outer rings are made of stamped metal sheet.

[0018] - The top and bottom caps are made of rigid plastic materials, such as polyamide, and optionally reinforced with glass fiber.

[0019] - The top and / or bottom caps may include a stiffening insert.

[0020] - The bearing is composed of a rolling bearing, with an annular rolling chamber defined between the inner and outer rings, and at least one row of rolling elements arranged in the rolling chamber.

[0021] - The rolling element is a ball.

[0022] - The lower ring cap includes a damping device specifically designed to form a seat for the suspension spring.

[0023] - The lower annular component includes an axial hub, and a first flange extends radially outward from the hub.

[0024] - The damping device includes a portion covering the lower radial surface of the first radial flange, the damping device being specifically designed to form a seat for the suspension spring.

[0025] - The damping device includes a portion covering the outer cylindrical surface of the hub, said portion of the damping device being dedicated to supporting radial loads from the suspension springs.

[0026] - The damping device includes a radial flange that extends radially outward beyond the first flange of the lower annular cap.

[0027] - The damping device is made of an elastic material such as rubber, thermoplastic elastomer (TPE), especially thermoplastic polyurethane (TPU), melt-processable elastomer (MPE) or porous polyurethane.

[0028] - The first sealing flange extends radially beyond the second sealing flange of the lower annular cap.

[0029] - The axial skirt of the upper ring cap radially surrounds the second sealing flange of the lower ring cap and axially points toward the first flange of the lower ring cap.

[0030] - The lower cap includes multiple annular circumferential grooves, each annular circumferential groove being defined between the upper sealing flange and the lower sealing flange.

[0031] - The lower annular cap includes a third flange extending radially outward from the cap, an annular circumferential groove defining an annular groove between the second sealing flange and the third sealing flange, and the third flange is surrounded by an axial skirt of the upper annular cap.

[0032] - The second sealing flange extends radially beyond the third sealing flange of the lower annular cap.

[0033] - Each of the annular circumferential grooves is provided with ribs spaced apart in the circumferential direction, the ribs extending radially outward from the lower cap, the ribs defining axially between sealing flanges defining the corresponding outer circumferential grooves, and the ribs being at least partially surrounded radially by a skirt.

[0034] - The upper ring cap includes a second axial skirt extending axially from the cap toward a second flange of the lower ring cap, the second axial skirt radially surrounding a third flange of the lower ring cap, and the second axial skirt being radially surrounded by a first axial skirt of the upper ring cap.

[0035] The ribs are equally spaced in the circumferential direction.

[0036] - The ribs of the different annular circumferential grooves are aligned with each other in the circumferential direction. Attached Figure Description

[0037] The invention will now be explained with reference to the accompanying drawings, which are illustrative examples and not intended to limit the scope of the invention. In the drawings:

[0038] - Figure 1 This is a top view of the suspension thrust bearing unit;

[0039] - Figure 2 It is used for Figure 1 A three-dimensional view of the lower cap of the unit;

[0040] - Figure 3 It is based on the present invention Figure 2 The first half-view of the axial section of the element; and

[0041] - Figure 4 It is based on the present invention Figure 2 The second half view of the axial section of the element. Detailed Implementation

[0042] A suspension thrust bearing unit 1, having a central axis X1, is mounted between a coil suspension spring (not shown) and a support block (not shown) connected to the chassis of a motor vehicle. This suspension thrust bearing unit 1 can be used, for example, in a MacPherson strut assembly in an automobile.

[0043] In the following text, the adjectives “axial” and “radial” are defined relative to the central axis X1 of the annular thrust bearing 1.

[0044] The suspension thrust bearing unit 1 includes an upper cap 3, a lower cap 4, and a single rolling bearing 5. These three components 3, 4, and 5 have an overall circular shape about the central axis X1.

[0045] The upper cap 3 is a one-piece component made of a plastic synthetic material, such as polyamide, and optionally reinforced with glass fiber. The upper cap 3 has an upper radial portion 30, an inner annular skirt 31 with a relatively small diameter extending toward the lower side of the suspension thrust bearing unit 1, and an outer annular skirt 32 with a relatively large diameter extending toward the lower side of the suspension thrust bearing unit 1.

[0046] The upper cap 3 is specifically designed for fixing to a support block (not shown) on the chassis of a motor vehicle.

[0047] The rolling bearing 5 includes an inner ring 50 made of pressed sheet metal, an outer ring 51 also made of pressed sheet metal, rows 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 the annular portions of the inner ring 50 and the outer ring 51. Alternatively, not shown, the rolling elements may be rollers.

[0048] The rolling bearing 5 is integrally located radially between the inner skirt 31 and the outer skirt 32 of the upper cap 3. The inner ring 50 is fitted inside the annular portion of the upper cap 3. The outer ring 51 is fitted onto the toroidal outer portion of the lower cap 4.

[0049] The lower cap 4 includes a hub 41 defining an inner bore 42. An inner skirt 31 defines an inner bore 33 for the suspension thrust bearing unit 1, in which an elongated shock absorber rod (not shown) is mounted. The inner skirt 31 of the upper cap 3 includes a plurality of outwardly projecting clips 34 pointing toward the hub 41 of the lower cap 4; the lower cap includes inwardly projecting clips 44 pointing toward the skirt 31. The clips 34 extend at a restricted angle, while the clips 44 are annular. The clips 34 and 44 cooperate to ensure axial assembly of the upper cap 3 and the lower cap 4. Each of the clips 34 and 44 includes a truncated tapered surface to facilitate assembly of the caps 3 and 4.

[0050] The lower cap 4 also includes an outwardly projecting radial flange 43 extending from the hub 41 toward the outside of the suspension thrust bearing unit 1.

[0051] The outer portion of the annular portion of the outer ring 51 supporting the rolling bearing 5 is disposed on the upper surface of the radial flange 43.

[0052] The hub 41 of the lower cap 4 supports radial loads and impacts from the suspension springs and also allows damped vibrations.

[0053] The lower cap 4 and the upper cap 3 also include a sealing component 6 to prevent contaminants from entering the internal space defined between the caps 3 and 4 and between the rings 50 and 51 of the bearing 5.

[0054] According to the present invention, the sealing component 6 is composed of a labyrinth seal designed as follows.

[0055] The lower annular cap 4 includes a first annular circumferential groove 60 disposed between a first sealing flange 61 and a second sealing flange 62 extending radially outward from the lower cap 4. More specifically, the sealing flanges 61 and 62 extend radially in a parallel annular pattern. The first sealing flange is a radially outward extension of the radial flange 43 of the lower cap 4. The second sealing flange 62 is axially shifted from the first sealing flange 61 toward the upper cap 3, thus defining the outer circumferential groove 60.

[0056] Advantageously, the first flange 61 extends radially beyond the second flange 62 of the lower annular cap 4.

[0057] The upper annular cap 3 includes an annular outer skirt 32 extending axially from the upper cap 3 toward the lower cap 4. A second flange 62 of the lower cap 4 is radially surrounded by the skirt 32. In this embodiment, the skirt 32 points toward the cap flange 43, and its ends radially face the first sealing flange 61 and axially face the second sealing flange 62. The groove 60, flanges 61 and 62, and skirt 32 form a tortuous chamber defining the labyrinth seal member 6.

[0058] As an alternative not shown, the skirt 32 may radially surround the first flange 61.

[0059] A radial first sealing flange 61 forms a first axial stop for contaminants, particularly for blocking axial and inclined jets of water or dust. A second flange 62 forms a second axial stop for contaminants, particularly for blocking residual contaminants not blocked by the first flange 61. A groove 60 guides residual contaminants from the second flange to the first flange. A skirt 32 forms a radial stop for contaminants. The skirt 32 also allows contaminants blocked by the second flange 62 to be redirected to the outside of unit 1. The gaps between the first flange 61 and the skirt 32, and between the second flange 62 and the skirt 32, are reduced to limit the entry size of contaminants between the lower and upper caps, but there is no contact between the lower and upper caps. Rotational friction between the caps 3 and 4, which rotate relative to each other via the bearing 5, is prevented.

[0060] Advantageously, the lower annular cap 4 includes a third sealing flange 63 extending radially outward from the cap 4. The third sealing flange 63 is annular in shape, extending radially parallel to the first flange 61 and the second flange 62. The third sealing flange 63 is axially displaced from the second sealing flange 62 toward the upper cap 3, thus defining a second outer circumferential groove 64.

[0061] The third flange 63 is surrounded by the axial skirt 32 of the upper annular cap 3.

[0062] Advantageously, the second flange 62 extends radially beyond the third flange 63 of the lower annular cap 4.

[0063] Advantageously, the upper annular cap 3 includes a second axial skirt 35 extending axially from the cap 3 toward the second flange 62 of the lower annular cap 4. The second axial skirt 35 radially surrounds the third flange 63 of the lower annular cap 4, and is radially surrounded by the first axial skirt 32 of the upper annular cap 3. An annular groove 36 is defined between the first skirt 32 and the second skirt 35 in the annular cap 3.

[0064] The radial third sealing flange 63 forms a third axial stop for contaminants, specifically to block residual contaminants not blocked by the first sealing flange 61 and the second sealing flange 62. A groove 64 guides residual contaminants from the second flange to the third flange. A skirt 35 allows contaminants blocked by the third flange 63 to be redirected to the outside of the unit 1. A groove 36 allows contaminants passing through the second flange 72 to be blocked and redirected. The gaps between the second flange 62 and the skirt 35, and between the third flange 63 and the skirt 35, are reduced to further limit the entry dimension for contaminants between the lower and upper caps, but there is no contact between the lower and upper caps. This design forms a multi-stage labyrinth seal for the unit.

[0065] According to the present invention, the first annular circumferential groove 60 and the second annular circumferential groove 64 are respectively provided with a plurality of ribs 65 and 66.

[0066] The first annular circumferential groove 60 is provided with a first series of ribs 65. The ribs 65 are circumferentially spaced apart within the groove 60. The ribs 65 extend radially outward from the lower cap 4 and are axially defined between the first sealing flange 61 and the second sealing flange 62.

[0067] The second annular circumferential groove 64 is provided with a second series of ribs 66. The ribs 66 are circumferentially spaced apart within the groove 64. The ribs 66 extend radially outward from the lower cap 4 and are axially defined between the second sealing flange 62 and the third sealing flange 63.

[0068] In the example shown, the ribs 65 and 66 of the different annular circumferential grooves 60 and 64 are aligned with each other in the circumferential direction.

[0069] As an alternative implementation, only one of the two slots 60, 64 is provided with a series of ribs. According to another embodiment, the lower cap 4 may include more than two annular circumferential outer slots, each annular circumferential outer slot being provided with a series of ribs.

[0070] Multiple ribs 65 and 66 enable the interruption of contaminants flowing into the labyrinth seal 6. More specifically, ribs 65 and 66 form circumferentially spaced axial walls within the grooves 60 and 64, while sealing flanges 61, 62, and 63 form radial walls. Flanges 61, 62, and 63 prevent contaminants from entering the grooves 60 and 64, and ribs 65 and 66 allow the interruption of contaminant dynamics within the grooves 60 and 64. Therefore, the efficiency of the labyrinth seal 6 is significantly improved.

[0071] According to an alternative not shown, the lower cap 4 may include a damping device made of an elastic material, such as rubber, thermoplastic elastomer (TPE), particularly thermoplastic polyurethane (TPU), melt-processable elastomer (MPE), or porous polyurethane. The damping device may be disposed on the underside of the lower cap 4 to support and dampen the spring.

[0072] The foregoing detailed description of representative, non-limiting examples of the invention with reference to the accompanying drawings is intended only to teach those skilled in the art further details for practicing the preferred aspects of this teaching, and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be used alone or in combination with other features and teachings to provide an improved suspension thrust bearing unit.

[0073] Furthermore, the representative examples described above, as well as the features of the appended independent and dependent claims, can be combined in ways not specifically and explicitly enumerated to provide additional useful implementations of this teaching.

Claims

1. 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 cap (3), a lower ring (51) mounted inside a lower annular cap (4), and at least one row of rolling elements (52) positioned between a raceway defined by the lower ring (51) and the upper ring (50), the lower annular cap (4) and the upper annular cap (3) being provided with sealing members (6) to prevent contaminants from entering the unit (1), the lower annular cap (4) including a radially spaced component from the lower cap (4). At least one annular circumferential groove (60; 64) is provided between an outwardly extending first sealing flange (61; 62) and a second sealing flange (62; 63). The upper annular cap (3) includes an annular outer skirt (32) extending axially from the upper cap (3) toward the lower cap (4). At least one of the flanges (62; 63) of the lower cap (4) is radially surrounded by the skirt (32). The groove (60; 64), the flanges (61, 62; 63), and the skirt (32) form a tortuous chamber defining the labyrinth sealing member (6). Its features are, The annular circumferential groove (60; 64) is provided with a plurality of ribs (65; 66), the ribs (65; 66) being spaced apart circumferentially within the groove (60; 64 ... 66) Extending radially outward from the lower cap (4), the ribs (65; 66) are axially defined between the first sealing flange and the second sealing flange (61, 62; 63), and the ribs (65; 66) are at least partially surrounded radially by the skirt (32).

2. The unit according to claim 1, characterized in that, The ribs (65; 66) are equidistant in the circumferential direction.

3. The unit according to any one of the preceding claims, characterized in that, The first flange (61) extends radially beyond the second flange (62) of the lower annular cap (4).

4. The unit according to claim 3, characterized in that, The axial skirt (32) of the upper ring cap (3) surrounds the second flange (62) of the lower ring cap (4) in the radial direction and points axially toward the first flange (61) of the lower ring cap (4).

5. The unit according to any one of the preceding claims, characterized in that, The lower annular cap (4) includes a third flange (63) extending radially outward from the cap (4), defining an annular circumferential groove (64) between the second flange (62) and the third flange (63), and the third flange (63) is surrounded by an axial skirt (32, 35) of the upper annular cap (4).

6. The unit according to claim 5, characterized in that, The second flange (62) extends radially beyond the third flange (63) of the lower annular cap (4).

7. The unit according to claim 6, characterized in that, The upper ring cap (3) includes a second axial skirt (35) extending axially from the second flange (62) of the lower ring cap (4) toward the second flange (62) of the cap (3), the second axial skirt (35) radially surrounding the third flange (63) of the lower ring cap (4), and the second axial skirt (35) being radially surrounded by the first axial skirt (32) of the upper ring cap (3).

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