Suspension thrust bearing device and suspension strut equipped with such a device

Abstract

The invention relates to a suspension thrust bearing device (10) for use with a suspension spring (3) in an automotive suspension strut of a vehicle. The device comprises: a bearing (20, 30, 40) having an upper annular bearing member (20, 42) and a lower annular bearing member (30, 41) which rotate relative to each other; and a damping element (70) made of elastic material and interposed between the lower annular bearing member (30, 41) and the suspension spring. The damping element comprises at least one deflection flange (73) for reducing the ingress of water and other contaminants between the upper annular bearing member and the lower annular bearing member. The damping element is provided with an annular groove (74) opening axially towards the suspension spring, the annular groove radially defining a spring support surface (75) on the inside and radially defining a deflection flange on the outside. The deflection flange has a truncated conical shape pointing axially towards the suspension spring.

Description

Technical Field

[0001] The invention relates to a suspension thrust bearing device, in particular a MacPherson type suspension thrust bearing device ("MacPherson Suspension Bearing Unit" or MSBU). The invention also relates to a strut for a motor vehicle, the strut comprising a shock absorber and such a suspension thrust bearing device. The technical field of the invention is the technical field of suspension systems, in particular the technical field of motor vehicle suspension systems. Background Art

[0002] In a known manner, a motor vehicle suspension system comprises a suspension strut supporting the wheel axle and the wheel. A suspension thrust bearing device is arranged in the upper part of the suspension strut, opposite the wheel and the ground, and between the suspension spring and an upper support block attached to the vehicle chassis ( / frame).

[0003] The suspension thrust bearing device includes at least one bearing (eg, a rolling bearing) including an upper annular bearing member and a lower annular bearing member that rotate relative to each other about a main axis.

[0004] The suspension thrust bearing arrangement enables the transmission of axial forces between the spring and the body of the vehicle, while at the same time allowing relative angular movement between the rotationally movable spring and a fixed support block attached to the body.

[0005] The shock absorbing function of the suspension thrust bearing device can be improved by using a shock absorbing element ( / damping element) made of elastic material and installed between the lower cup ( / cup-shaped member / lower ring) (cup) and the suspension spring.

[0006] Such suspension thrust bearing devices (especially MSBU type suspension thrust bearing devices) are required to be used in aggressive environments. For example, the vehicle may be driven on flooded, dusty or muddy roads and then cleaned with a high-pressure cater jet. Under these conditions, water or other contaminating particles may enter the struts, especially the bearings, with adverse consequences on their service life and their various properties.

[0007] In this respect, it is known from document US 2008 / 0031562 A1 to provide a deflecting flange extending substantially radially from a damping element, said flange being designed to form a flow deflector for reducing the ingress of water and other contaminants into the interior of the suspension thrust bearing arrangement.

[0008] However, the axial load of the suspension spring onto the shock absorbing element may cause axial and radial deformation of the element. More specifically, it has been observed that the deflection flange moves upward towards the upper cup ( / upper cup / upper ring). This undesirable flange displacement leads to contact with the upper cup and then increases the suspension thrust bearing device torque and negatively affects the device performance. The deflection flange and the upper cup may wear and have a shortened service life. It also causes additional noise that must be prevented. The deflection flange can also move downward towards the underside of the suspension strut, resulting in a loss of sealing performance. Summary of the invention

[0009] The object of the present invention is to overcome these disadvantages by proposing an enhanced suspension thrust bearing arrangement.It is desirable to provide a suspension thrust bearing arrangement which is relatively inexpensive, has good operational reliability and has an increased service life.

[0010] To this end, the present invention is directed to a suspension thrust bearing arrangement for use with a suspension spring in an automotive ( / motor vehicle) suspension strut of a vehicle.

[0011] The suspension thrust bearing device includes a bearing having an upper annular bearing member and a lower annular bearing member that rotate relatively.

[0012] The suspension thrust bearing device also includes a damping element, the damping element is made of an elastic material and has a radial portion between the lower annular bearing member and the suspension spring. The damping element also includes at least one deflecting flange, the at least one deflecting flange extends outwardly and generally radially from the radial portion, for reducing the ingress of water and other contaminants between the upper annular bearing member and the lower annular bearing member.

[0013] According to the present invention, the radial portion of the shock-absorbing element has an axial material thickness L1; an upper annular groove is provided on the upper side of the radial flange of the shock-absorbing element, and the annular groove receives a protrusion extending axially downward from the lower annular bearing member, and the shock-absorbing element has an axial material thickness L2 at the level of the annular groove; and a lower annular groove is provided on the lower side of the shock-absorbing element, which is axially open toward the suspension spring, and the annular groove radially defines a spring support surface on the inner side and radially defines the deflecting flange on the outer side, and the shock-absorbing element has an axial material thickness L3 defined between the lower annular groove and the lower annular bearing member and a radial material thickness L4 defined between the lower annular groove and the upper annular groove.

[0014] The damping element is such that: the ratio between L2 and L1 is strictly less than 1; the ratio between L3 and L1 is strictly less than 1; and the ratio between L4 and L1 is less than or equal to 1.

[0015] According to another advantageous but non-mandatory aspect of the present invention, the suspension thrust bearing device may include one or more of the following features:

[0016] The suspension thrust bearing device includes a bearing having: a first ring fixed to an upper cover to form an upper annular bearing member of the suspension thrust bearing; and a second ring fixed to a lower cover to form a lower annular bearing member of the suspension thrust bearing.

[0017] The first ring and the second ring are made of stamped metal sheets.

[0018] The upper cover and the lower cover are made of rigid plastic material.

[0019] The upper cover and / or the lower cover may include reinforcing inserts.

[0020] The upper cover and / or the lower cover are overmolded onto the reinforcement insert.

[0021] The bearing is a rolling bearing, the first ring and the second ring define an annular rolling chamber between them, and at least one row of rolling elements is arranged in the rolling chamber.

[0022] The rolling elements are balls.

[0023] The deflection flange has a frustoconical shape axially directed towards the suspension spring.

[0024] The deflection flange is provided with a shoulder which radially abuts the front surface of the lower annular bearing member.

[0025] The shoulders are annular.

[0026] The ratio between L4 and L2 is less than or equal to 1.

[0027] The damping element is formed directly on the lower annular bearing component.

[0028] The damping element comprises a rubber thermoplastic elastomer (TPE), in particular, the rubber thermoplastic elastomer (TPE) is a thermoplastic polyurethane (TPU), a melt processible elastomer (MPE) or an elastomer cellular foam.

[0029] The invention also relates to a motor vehicle suspension strut comprising a shock absorber rod, a suspension spring and a suspension thrust bearing arrangement as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will now be explained with reference to the accompanying drawings as illustrative examples without limiting the object of the invention. In the drawings:

[0031] Figure 1 is a cross-sectional view of a suspension strut according to a first embodiment of the present invention, the suspension strut including a suspension thrust bearing unit also according to the first embodiment of the present invention, and a shock absorber rod and a suspension spring; and

[0032] Figure 2 yes Figure 1 Detailed cross-section of a suspension thrust bearing assembly. DETAILED DESCRIPTION

[0033] exist Figure 1 The suspension strut 1 shown in the middle part is incorporated into the motor vehicle suspension system. The suspension strut 1 supports the vehicle axle and the wheel, which are not shown for the purpose of simplicity. The suspension strut 1 extends along a main axis X1, which is located in a substantially vertical direction when the vehicle's wheels are parked on a flat ground. The suspension strut 1 includes a damper piston, a helical suspension spring 3, and a suspension thrust bearing device 10, and the damper piston includes a piston body and a damper rod 2 with an axis X2. Figure 1 The rod 2 and the spring 3 are partially shown in FIG. 1 , while the piston body is not shown for the sake of simplicity.

[0034] A suspension thrust bearing device 10 having a main axis X10 is mounted between a support block (not shown) connected to the chassis of a motor vehicle and the spring 3. Figure 1 As shown, when the suspension system of the vehicle is at rest, the axis X2 and the axis X10 coincide with the main axis X1.

[0035] In the following, the adjectives “axial” and “radial” are defined relative to the main axis X10 of the annular thrust bearing device 10 .

[0036] The suspension thrust bearing device 10 comprises an upper cap 20, a lower cap 30 and a single rolling bearing 40. In this embodiment, these three components 20, 30 and 40 have a globally circular shape around a main axis X40 which coincides with the main axis X10 when the suspension system of the vehicle is at rest.

[0037] The upper cover 20 comprises a one-piece part made of a plastic composite material (e.g., made of polyamide, optionally reinforced with glass fibers). The upper cover 20 has a flange 21 extending in the radial direction, an inner hub 22 extending in the axial direction, having a relatively small diameter and extending toward the lower side of the suspension thrust bearing device 10, and an outer skirt 23 extending in the axial direction, having a relatively large diameter and extending toward the lower side of the suspension thrust bearing device 10. The inner hub 22 defines an inner hole 24 for the suspension thrust bearing device 10 in which the shock absorber rod 2 is mounted.

[0038] The upper cover 20 is specially adapted to be fixed to a support block of a chassis of a motor vehicle.

[0039] The rolling bearing 40 includes an inner ring 41, which is a pressed sheet metal; an outer ring 42, which is also a pressed sheet metal; a row of rolling elements 43, where the rolling elements 43 are balls; and a cage 44 for maintaining regular circumferential spacing between the rolling elements 43. The rolling elements 43 are arranged in a rolling chamber defined between a raceway formed by a toroidal portion of the inner ring 41 and a raceway formed by a toroidal portion of the outer ring 42.

[0040] As an alternative, not shown, rolling elements need not be used, but the inner and outer rings could be in direct contact with each other using suitable low friction materials, coatings or lubricants.

[0041] The rolling bearing 40 is located as a whole between the inner hub 22 and the outer skirt 23 of the upper cover 20 in the radial direction. The inner ring 41 is assembled in the inner part of the annular ring of the lower cover 30. The inner ring 41 and the lower cover 30 form a lower annular bearing member. The outer ring 42 is assembled to the outer part of the annular ring provided on the lower side of the flange 21 of the upper cover 20. The outer ring 42 and the upper cover 20 form an upper annular bearing member. The upper annular bearing member and the lower annular bearing member rotate relative to the axis X40.

[0042] The lower cover 30 includes a hub 31 extending in the axial direction, the hub 31 defining an inner hole 33 in which the rod 2 extends in the axial direction. The lower cover 30 also includes a radial flange 32 extending radially outward from the hub 31. The outer ring of the inner ring 41 supporting the rolling bearing 40 is arranged on the upper surface of the radial flange 32.

[0043] The lower cover 30 includes a stiffening insert 34 extending along the hub 31 and the flange 32 to support the load and impact applied by the spring 3. The stiffening insert can be metal or rigid plastic. As an alternative not shown, the upper cover 20 can also include a stiffening insert.

[0044] An inner sealing means 50 is provided between the inner periphery of the radial flange 32 of the lower cover 30 and the inner hub 22 of the upper cover 20. An outer sealing means 60 is provided between the outer periphery of the radial flange 32 of the lower cover 30 and the outer skirt 23 of the upper cover 20.

[0045] The lower cover 30 is also provided with a shock absorbing element 70 made of elastic material to be able to filter vibrations.

[0046] The damping element 70 includes a radial portion 71 and a tubular axial portion 72. The radial portion 71 is tightly fastened to the lower side of the radial flange 32 of the lower cover 30. The radial portion 71 includes a lower radial side for receiving the end turns of the suspension spring 3 in a bearing contact manner. The radial portion 71 of the damping element 70 supports the axial load and impact from the suspension spring 3.

[0047] The tubular axial portion 72 extends axially from the radial portion 71 toward the lower side of the suspension thrust bearing device 10. The tubular axial portion 72 is tightly fastened to the outer cylindrical surface of the hub 31 of the lower cover 30. The tubular axial portion 72 of the damping element 70 supports radial loads and impacts from the suspension spring 2.

[0048] The tubular axial portion 72 and the radial portion 71 of the damping element 70 are connected together to cover the outer surfaces of the axial hub 31 and the radial flange 32 of the lower cover 30 .

[0049] The shock absorbing element 70 is made of an elastic material such as rubber thermoplastic elastomer (TPE), in particular, thermoplastic polyurethane (TPU), melt processible elastomer (MPE), or elastomer cellular foam.

[0050] Advantageously, the shock absorbing element 70 is overmoulded onto the lower cover 30. Alternatively, the shock absorbing element is fixed to the lower cover 30 by any suitable means, such as glue.

[0051] The damping element 70 further comprises a deflecting flange 73 to prevent water and contaminants from entering the interior of the device 10, and more particularly, to prevent water and contaminants from entering the interior of the bearing 40. The deflecting flange 73 extends the radial portion 71 radially outward from the large diameter edge. The deflecting flange 73 extends radially outward beyond the large diameter edge of the radial flange 32 of the lower cover 30. Advantageously, the deflecting flange 73 extends radially outward at least according to the same diameter as the outer skirt 23 of the upper cover 20.

[0052] According to an advantageous embodiment of the invention, the deflection flange 73 has a frustoconical shape directed axially towards the underside of the device 10 .

[0053] The damping element 70 and the deflection flange 73 are formed integrally, the deflection flange being advantageously molded.

[0054] The damping element 70 is also provided on its lower side with a lower annular groove ( / recess) 74 which is open in the axial direction toward the suspension spring 3. More specifically, the lower side of the radial portion 71 extended by the deflection flange 73 is provided with said annular groove 74.

[0055] The lower annular groove 74 radially defines a spring support surface 75 on the inside and radially defines the deflection flange 73 on the outside. In other words, the annular groove 74 radially disconnects the deflection flange 73 from the surface 75 against which the suspension spring 3 applies an axial load. The two functions ensured by the damping element 70 are thus distinguished from each other. The annular groove may be conical in shape, circular in shape or any other suitable shape.

[0056] The lower surface of the radial flange 32 of the lower cover 30 is provided with a portion 35 protruding in the axial direction pointing to the lower side of the device 10. The upper surface of the radial portion 71 of the damping element 70 is provided with an upper annular groove 76, which is open to the upper side of the device 10 and receives the portion 35 protruding in the axial direction.

[0057] Advantageously, the portion 35 and the groove 76 have corresponding shapes. Advantageously, the groove 76 is formed during the operation of forming (molding) the radial portion 71 onto the portion 35 of the lower cover 30 .

[0058] The radial portion 71 of the damping element 70 has an axial material thickness L1. The damping element 70 has an axial material thickness L2 at the level of the upper annular groove 76. The damping element has an axial material thickness L3 defined between the lower annular groove 74 and the lower annular bearing member 32 and a radial material thickness L4 defined between the lower annular groove 74 and the upper annular groove 76.

[0059] The damping element is such that: the ratio between L2 and L1 is strictly less than 1; the ratio between L3 and L1 is strictly less than 1; and the ratio between L4 and L1 is less than or equal to 1.

[0060] According to an advantageous embodiment of the invention, the ratio between L4 and L2 is less than or equal to 1.

[0061] According to another advantageous embodiment of the invention, the deflecting flange 73 is provided with a shoulder 77 which radially abuts against the front face of the radial flange 32 of the lower cover 30 .

[0062] Representative, non-limiting examples of the present invention are described in detail above with reference to the accompanying drawings. This specific embodiment is intended only to teach those skilled in the art more details for practicing the preferred aspects of the present teachings, and is not intended to limit the scope of the present invention. In addition, each of the additional features and teachings disclosed above can be used alone or in combination with other features and teachings to provide an improved cam follower roller device.

[0063] Furthermore, various features of the above-described representative examples and various independent and dependent claims may be combined in ways not specifically and expressly listed to provide additional useful embodiments of the present teachings.

Claims

1. A suspension thrust bearing device (10) for use with a suspension spring (3) in a motor vehicle suspension strut of a vehicle, comprising: A bearing (40) having an upper annular bearing member and a lower annular bearing member that rotate relative to each other; and a damping element (70) made of an elastic material and having a radial portion (71) between the lower annular bearing member and the suspension spring (3), the damping element (70) further comprising at least one deflection flange (73) extending outwardly and generally radially from the radial portion (71) for reducing any ingress of water and other contaminants between the upper annular bearing member and the lower annular bearing member; The invention is characterized in that the radial portion (71) of the shock absorbing element (70) has an axial material thickness L1; an upper annular groove (76) is provided on the upper side of the radial flange of the shock absorbing element (70), the upper annular groove (76) receives the protrusion (35) extending axially downward from the lower annular bearing member, and the shock absorbing element (70) has an axial material thickness L2 at the level of the upper annular groove (76); and a lower annular groove (74) is provided on the lower side of the shock absorbing element (70) which is open axially toward the suspension spring, the lower annular groove (74) radially defines a spring support surface (75) on the inner side, and radially defines the deflection flange (73) on the outer side, and the shock absorbing element (70) has an axial material thickness L3 defined between the lower annular groove (74) and the lower annular bearing member, and a radial material thickness L4 defined between the lower annular groove (74) and the upper annular groove (76); The damping element is such that: the ratio between L2 and L1 is strictly less than 1; the ratio between L3 and L1 is strictly less than 1; and the ratio between L4 and L1 is less than or equal to 1.

2. The suspension thrust bearing device according to claim 1, characterized in that: The suspension thrust bearing device (10) comprises a bearing, wherein the bearing has: a first ring (42) fixed to an upper cover (20) so as to form an upper annular bearing component of the suspension thrust bearing device (10); and a second ring (41) fixed to a lower cover (30) so as to form a lower annular bearing component of the suspension thrust bearing device (10).

3. The suspension thrust bearing device according to claim 2, characterized in that: The bearing (40) is a rolling bearing, the first ring (42) and the second ring (41) define an annular rolling chamber therebetween, and at least one row of rolling elements (43) is arranged in the rolling chamber.

4. The suspension thrust bearing device according to any one of claims 1 to 3, characterized in that: The deflection flange (73) has a frustoconical shape pointing axially toward the suspension spring.

5. The suspension thrust bearing device according to any one of claims 1 to 3, characterized in that: The ratio between L4 and L2 is less than or equal to 1.

6. The suspension thrust bearing device according to any one of claims 1 to 3, characterized in that: The deflection flange (73) is provided with a shoulder (77) which radially abuts the front surface of the lower annular bearing member.

7. A motor vehicle suspension strut (1) comprising a shock absorber rod (2), a suspension spring (3) and a suspension thrust bearing arrangement (10) according to any one of the preceding claims.

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