FR2966084A1 - Suspension stop device for MacPherson strut in motor vehicle, has self-lubricating element in contact over its entire surface with complementary surfaces of upper and lower caps, and absorbing axial and radial forces of suspension spring - Google Patents

Abstract

The device (30) has an upper cap (32) mounted on a chassis of a motor vehicle, and a lower cap (33) having a lower surface (39c) forming a support surface for a suspension spring (31) intended to exert axial and radial forces on the device. A self-lubricating element (35) is arranged between the upper cap and the lower cap for forming a slider bearing. The self-lubricating element is in contact over its entire surface with complementary surfaces of the upper cap and the lower cap, and absorbs axial and radial forces of the suspension spring.

Description

B10-2983EN 1 Suspension stop device

The present invention relates to the field of suspension stop devices used in particular on motor vehicles in the suspension struts of motor vehicle steering wheels. Conventionally, a suspension stop comprises a rolling bearing forming axial stop and comprising a lower ring and an upper ring between which is arranged a row of rolling elements, for example balls or rollers. Preferably, an angular contact bearing is used which makes it possible to take up both the radial forces and the axial forces exerted on the suspension stop device. The lower and upper rings are generally mounted in contact with lower or upper support pieces or supports, such as cups or covers. The upper and lower covers form a housing for the rings of the bearing and make it possible to ensure the interface between said rings and the neighboring elements.

Such a suspension stop device is disposed in the upper part of the suspension strut between a suspension spring and an upper element secured to the vehicle body. The suspension spring is arranged around a damper piston rod whose end can be secured to the vehicle body by means of a resilient block filtering vibrations. The suspension spring is axially supported, directly or indirectly, on the lower bearing cover of the suspension stop device. The upper support cover is fixed in relation to the vehicle body.

The suspension abutment thus makes it possible to transmit axial forces between the suspension spring and the vehicle body while allowing relative angular movement between the rotatable lower cover and the top cover. This relative angular movement can result from steering of the steered wheels and / or compression of the suspension spring. In order to ensure optimal operation of the bearing, the suspension stop device requires the presence of a lubricant inside the rolling bearing, that is to say the space between the two rings. In addition, it is necessary to retain the lubricant inside the bearing, and at the same time to prevent the penetration of pollutants, solid or liquid, inside the bearing. For this purpose, joints can be arranged at the junction between the two rings. These seals can be attached either to one of the rings or to the cage for holding the rolling elements. Since the wear speed of the balls is sensitive to vibrations, it is difficult to maintain a flexible turning after a long period of time. The European patent application EP0656483, which makes it possible to respond to the problem raised above, describes a suspension stop device comprising a flat synthetic sliding element capable of taking up the axial or radial forces exerted by the suspension spring. However, this suspension stop device does not allow to take up both the axial and radial forces exerted by the suspension spring. Japanese Patent Application JP8 159 160 discloses a suspension stop device comprising an upper cover and a lower cover forming between them frustoconical tracks cooperating with a frustoconical sliding element in partial contact with the covers by sectors separated by grooves. The grooves being intended to serve as a reservoir for lubricant. Although this suspension stop device makes it possible to take up the axial and radial forces, the complex structure of the sliding elements does not allow optimal operation of a high-load suspension stop device having a long service life. In addition, the manufacturing cost of such a sliding element is important.

The object of the invention is to provide a suspension abutment carrying high loads, simple to manufacture and low cost, while being able to transmit the radial and axial forces exerted by the suspension spring.

Another object of the invention is to provide a suspension stop device with good friction properties. The invention relates to a suspension stop device for a motor vehicle comprising an upper cover intended to be mounted on the chassis of the motor vehicle, and a lower cover having a lower surface forming a bearing surface for a suspension spring intended for exert axial and radial forces to the suspension stop device. The suspension stop device comprises a self-lubricating element disposed between the upper cover and the lower cover, sliding bearing, said self-lubricating element being in contact on its entire surface with complementary surfaces of the upper cover and the lower cover and being capable of take up the axial and radial forces exerted by the suspension spring. The self-lubricating element being in contact with the lower cover and the upper cover over its entire surface, without any material recess, makes it possible to withstand high loads as well as to offer a long service life of the suspension stop device, in the Since the sliding element is self-lubricating, its life does not depend on the presence of lubricant in particular recesses. The term "sliding bearing" means the assembly formed by the upper and lower covers and the self-lubricating element. Advantageously, the self-lubricating element is frustoconical and comprises an upper surface in contact on its entire surface with a lower surface of the upper cover and a lower surface in contact on its entire surface with an upper surface of the lower cover.

The self-lubricating element may be made of fabric or glass fibers and may have a thickness of between 0.1 mm and 10 mm. According to another embodiment, the self-lubricating element comprises two axial portions and two radial portions, so as to form a self-lubricating element having in cross section a cross-shaped profile. Advantageously, each of the radial portions comprises an upper surface in contact on its entire surface with a lower surface of the upper cover and a lower surface in contact on its entire surface with an upper surface of the lower cover. For example, the axial portions extend axially opposite one another with respect to the radial portions. The upper cover and the lower cover may each comprise a groove opening respectively on the lower surface and the upper surface, said grooves being shaped to cooperate with one of the axial portions of the self-lubricating element. Preferably, the self-lubricating element has a constant thickness. According to another embodiment, the self-lubricating element is of toroidal shape with an axis substantially coaxial with the vertical axis of the suspension stop device. Advantageously, the upper cover is provided with an outer annular skirt and an inner annular skirt surrounding the lower cover, and delimiting with the lower cover an annular passage forming a labyrinth seal. For example, at least one of the annular skirts of the upper cover comprises a hook intended to cooperate with a corresponding hook of the lower cover. According to a second aspect, the invention relates to a suspension strut comprising a suspension stop device according to one of the preceding claims. Other objects, features and advantages of the invention will become apparent on reading the following description, given solely by way of nonlimiting example, and with reference to the appended drawings in which: FIG. 1 is a sectional view axial view of a suspension stop device according to a first embodiment of the invention, - Figure 2 illustrates in exploded perspective the suspension stop device of Figure 1; - Figure 3 is an axial sectional view of a suspension stop device according to a second embodiment of the invention; FIG. 4 is an axial sectional view of a suspension stop device according to a third embodiment of the invention, FIG. 5 is a sectional view VV of a suspension abutment of FIG. 4, and FIG. 6 illustrates a suspension abutment according to another embodiment. The suspension stop device 10, referenced as a whole in FIGS. 1 and 2, is intended to be integrated in a suspension strut of a motor vehicle (not shown) between an element of the chassis of the motor vehicle and a suspension spring. 11 helical type, of which only the upper turn is shown. The suspension stop device 10 is arranged around a damper rod extending axially in the form of a cylinder of revolution (not shown), of vertical Y axis supposed. The suspension spring 11 is mounted around the damper rod. The suspension stop device 10, of axis Y, comprises an upper support cover 12 intended to be mounted directly or indirectly on the chassis of the vehicle, a lower support cover 13 having reinforcing ribs 14 of substantially rectangular section. in the vicinity of its bore 13a and a self-lubricating sliding element 15 disposed between said lower cover 13 and the upper cover 12. The assembly consisting of the lower cover 13, upper 12 and the sliding element 15 form a sliding bearing. The suspension stop device 10 allows a rotational movement between the lower support cover 13 and the upper support cover 12 and transmits the axial and radial forces between the suspension spring 11 and the vehicle frame in a reduced axial space . The upper cover 12, of generally frustoconical shape, has a bore 12a Y1 axis slightly inclined relative to the Y axis of the suspension stop device 10. The upper cover 12 comprises a solid annular portion 16 whose upper surface 16a is intended to come into contact with an element of the chassis of the vehicle. The annular solid portion 16 has a substantially conical external shape, the section of which varies according to the circumference of the upper seat 12. The annular solid portion 16 has an outer annular axial skirt 17 of smaller thickness than the solid portion 16, radially connected to the upper surface 16a by a rounded portion 16b and extending axially downwardly and radially outwardly by an annular flange 17a. The outer annular flange 17a delimits, with an annular flange 18a of the lower cover 13, a narrow passage 19a, forming a labyrinth seal. An inwardly directed hook 17b, which may be continuous or discontinuous circumferentially, is formed on the bore 17c of the outer annular skirt 17 adjacent its lower end 17d. The hook 17b is directed radially inward towards the lower cover 13 and can cooperate with corresponding hooks 20a of the lower cover 13, directed radially outwardly, so as to form a labyrinth type seal. The annular solid portion 16 has a bottom surface 16c of generally frustoconical shape in contact with a sliding element 15 illustrated in detail in FIG.

The lower bearing cowl 13 has a radial plate-shaped portion 19 and an annular axial skirt 21 disposed inward and extending axially downwardly opposite the upper support cowl 12. The axial skirt 21 has at its lower end, a frustoconical portion 21a extending through a radial bead 21b directed outwardly defining a groove 21c allowing, for example, the retention of a protective bellows (not shown) for the damper rod . Said radial bead 21b can be continuous or discontinuous depending on the circumference of the lower cover 13. The lower end of the axial skirt 21 extends radially inwardly by a radial portion 13b, slightly inclined downwards, and having a bore 13a for the passage of the damper rod. The radial plate-shaped portion 19 comprises a cylindrical outer surface 19b of small axial dimension from the end of which extends an annular radial surface 19c delimiting a bearing surface for the upper end turn of the spring of suspension 11. The radial surface 19c extended inwards and downwards by a rounded surface 19d connected to the outer cylindrical surface 21d of the axial skirt 21. The axis Yz perpendicular to the radial bearing surface 19c is slightly inclined relative to the vertical axis Y of the suspension device 10, so as to reduce the radial forces exerted by the suspension spring 11. The outer cylindrical surface 21d allows the centering of the suspension spring 11. The radial portion 19 has a dimension axial varying circumferentially of the lower cover 13 and may have a radial tongue 19e extending outwardly so as to come beyond the annular outer skirt 17 of the upper support cowl 12. In the vicinity of the upper end of the cylindrical outer surface 19b, the radial plate 19 of the lower cowl 13 has an annular axial rib 20 extending towards the upper cowl 12. The axial rib 20 comprises a hook 20a directed axially outwards in the direction of the top cover 12. The hook 20a may be continuous or circumferentially discontinuous and is disposed above the hook 17b of the top cover 12, so as to be able to interfere diametrically with said hook 20a in case of beginning of separation of the upper cover 12 and the lower cover 13. The hook 20a therefore forms an axial retention means of the upper cover 12 relative to the lower cover 13 in order to avoid separation of the elements constituting the device 10 before mounting it in the strut of the vehicle. The hook 20a follows axially downwards to a groove 20b intended to cooperate with the hook 17b of the upper cover 12. A radial annular passage 20c exists between the hook 17b of the upper cover 12 and the groove 20b of the lower cover 13. The rib axial 20 of the radial portion 19 is extended inwardly by an upper surface 20d of generally frustoconical shape intended to cooperate with the self-lubricating sliding member 15. The Yz axis perpendicular to the bearing surface 19c and the axis Y1 of the upper support cap 12 being positively inclined with respect to the Y axis of the suspension device 10, which makes it possible to reduce the radial forces exerted by the suspension spring 11. As a variant, the Y, Y1 and Yz axes could be substantially parallel to each other. Such a suspension stop device 10 may comprise sealing means (not shown).

FIG. 2 illustrates in detail a self-lubricating element 15 disposed between the upper cover 12 and the lower cover 13. In the example illustrated in FIGS. 1 and 2, the sliding element 15 has a relatively small constant thickness of between 0.1 mm and 2 mm, and preferably equal to 0.5 mm. The generally frustoconical sliding member comprises an upper surface 15a in full contact with the bottom surface 16c of the top cover 12 and a bottom surface 15b in full contact with the upper surface 20d of the bearing cover. lower 13. The sliding element is made of fabric or glass fibers comprising a self-lubricating component, such as a mineral or synthetic oil, graphite, molybdenum disulfide, or PTFE. Alternatively, the sliding element can be made mainly of polymer such as PA, PP or POM. The embodiment illustrated in FIG. 3, in which the same elements have the same references, comprises a sliding element different from that illustrated in FIGS. 1 and 2. The sliding element 25 illustrated in FIG. 3 is of general shape. frustoconical and comprises an upper surface 25a in contact over its entire surface with the lower surface 16c of the upper support cap 12 and a lower surface 25b in contact with its entire surface with the upper surface 20d of the lower support cap 13. The The sliding element 25 has a greater thickness than the sliding element 15 illustrated in FIGS. 1 and 2. The thickness of the sliding element 25 is between 1 mm and 10 mm, and preferably equal to 3 mm. Such a sliding element 25 makes it possible to transmit radial and axial forces exerted by the suspension spring 11 greater than with a sliding element 15 illustrated in FIGS. 1 and 2. The suspension stop device 30 illustrated as a whole at FIGS. Figures 4 and 5 differs from the stop device illustrated in Figures 1 and 2 by the shape of the upper and lower covers and the sliding element.

The suspension stop device 30 is intended to be integrated in a suspension strut of a motor vehicle (not shown) between an element of the chassis of the motor vehicle and a suspension spring 31 of helical type, of which only the upper turn is represented. The suspension stop device 30 is disposed around a damper rod extending axially in the form of a cylinder of revolution (not shown), of vertical axis Y assumed. The suspension spring 31 is mounted around the damper rod.

The suspension stop device 30, of axis Y, comprises an upper support cover 32 intended to be mounted directly or indirectly on the chassis of the vehicle, a lower support cover 33 having reinforcing ribs 34 of substantially rectangular section. in the vicinity of its bore 33a and a self-lubricating sliding member 35 disposed between said lower cover 33 and the upper cover 32. The suspension stop device 30 allows rotational movement between the lower support cover 33 and the upper cover 32 and transmits the axial and radial forces between the suspension spring 31 and the vehicle frame in a reduced axial size. The upper support cowl 32, generally of annular collar shape, may consist of a one-piece piece made of synthetic material such as, for example, polyamide PA 6.6, reinforced or not with glass fibers. The upper cover 32 has a bore 32a of axis Y1 substantially equal to the Y axis of the suspension stop device 30. The upper cover 32 comprises an annular solid portion 36 whose upper surface 36a is intended to come into contact with a vehicle chassis element. The annular solid portion 36 has an internal annular axial skirt 37 of smaller thickness than the solid portion 36, and an outer annular skirt 38 also of smaller thickness than the solid portion 36, said outer annular skirt 38 radially surrounding the skirt The annular skirts extend axially downwardly from the solid portion 36. The outer annular skirt 38 comprises an annular flange 38a extending axially downward and radially outwardly, and delimiting with a annular flange 39a of the lower cover 33, a narrow passage 381), forming a labyrinth seal. The solid portion 36 includes a flat bottom surface 36b in contact with the sliding member 35.

The lower end of the inner annular skirt 37 comprises a hook 37a directed outwards towards the lower cover 33, which may be continuous or discontinuous circumferentially. The hook 37a can cooperate with corresponding hooks 40a of the lower cover 33, directed radially inwardly, so as to form a labyrinth type seal. The lower support cover 33 may consist of a one-piece piece made of synthetic material such as, for example, polyamide PA 6.6, reinforced or not with glass fibers and comprises a portion 39 in the form of a radial plate 39 and an annular axial skirt 41 disposed inwardly and extending axially downwardly opposite the upper cover 32. The axial skirt 41 has at its lower end a rounded portion 41a extending through a radial bead 41b directed outwardly defining a groove 41c allowing, for example, the retention of a protective bellows (not shown) for the damper rod. The axial skirt 41 may also comprise at its lower end, a radial bead 41e directed inwards and allowing, for example, the axial retention of the damper rod. Said radial beads 41b, 41e may be continuous or discontinuous depending on the circumference of the lower cover 33. The lower end of the axial skirt 41 extends radially inwardly by a radial portion 331), slightly inclined downwards, and having a bore 33a for the passage of the damper rod. The radial plate-shaped portion 39 has a cylindrical outer surface 39b of axial dimension varying along the circumference of the lower cover 33, and from the lower end of which extends an annular radial surface 39c delimiting a bearing surface. for the upper end turn of the suspension spring 31. The radial surface 39c is extended inwardly and downwardly by a rounded surface 39d connected to the outer cylindrical surface 41d of the axial skirt 41. The outer cylindrical surface 41d allows the centering of the suspension spring 31.

In the vicinity of the upper end of the cylindrical outer surface 39b, the radial plate 39 of the lower cover 33 has an annular flange 39a extending through a flat upper surface 40 cooperating with the sliding element 35.

The upper surface 40 extends radially inwardly by a hook 40a directed towards the upper cover 32. The hook 40a may be continuous or discontinuous circumferentially and is disposed above the hook 37a of the upper cover 32, so as to be able to to interfere diametrically with said hook 40a in the event of the beginning of separation of the upper cover 32 and the lower cover 33. The hook 40a therefore forms an axial retention means of the upper cover 32 relative to the lower cover 33 in order to avoid separation of the elements constituting the device 30 before mounting in the strut of the vehicle. The hook 40a follows axially downwards to an axial portion 40b intended to cooperate with the hook 37a of the upper cover 32. A radial annular passage 40c exists between the hook 37a of the upper cover 32 and the axial portion 40b of the lower cover 33. The axial portion 40b is extended by a frustoconical portion 40d connecting the axial skirt 41 to the radial portion 39. The radial portion 39 has an axial dimension varying according to the circumference of the lower cover 33 and the bearing surface 39c, as illustrated. in FIG. 5, is slightly inclined along the circumference of the lower cover 33, so as to support the suspension spring 31. As illustrated in FIG. 5, the radial portion 39 comprises a radial rib 39e extending radially towards the outside. outside and having an outer diameter greater than the outer diameter of the outer annular skirt 38 of the upper seat 32. The sliding member 35 comprises two portions ax iales 41, 42 and two radial portions 43, 44 arranged to have in cross section a cross-shaped profile. Each of the radial portions 43, 44 includes an upper surface 43a, 44a in full contact with the lower surface 36b of the top cover 32, and a lower surface 431), 441) in full contact with the upper surface. 40 of the lower cover 33. The axial portions 41, 42 extending axially opposite to each other relative to the radial portions 43, 44. The axial portion 41 extends in a groove 45 formed in the lower cover 33 and opening on the upper surface 40 and the axial portion 42 extends in a groove 46 formed in the upper cover 32 and opening on the lower surface 36b. The width of the grooves 45, 46 is substantially equal to the thickness of the axial portions 41, 42, while leaving a slight clearance so as to facilitate insertion of the axial portions 41, 42 in said grooves 45, 46. The hood lower support means 33 comprises sealing means 47, 48. The first sealing means 47 of generally annular shape, rests axially on the annular flange 39a delimited between the outer cylindrical surface 39b and the upper flat surface 40. The means seal 47 comprises an axial annular portion 47a and a sealing lip 47b extending from the axial portion 47a to the outer annular skirt 38 of the upper cover 32. The axial contact between the outer annular skirt 38 and the sealing lip 47b makes it possible to prevent the intrusion of pollutants inside the suspension stop device 30, and in particular towards the sliding element 35. In the example illustrated, the device for suspension stopper 30 comprises a second sealing means 48 of generally annular shape, resting axially on an upper surface 40e of the lower cover 33 delimited between the hook 40a and the flat upper surface 40. The sealing means 48 comprises a radial portion 48a and a sealing lip 48b extending from the radial portion 48a to the lower surface 36b of the top cover 32. The sealing means 47 and 48 may be overmoulded, glued or forced into the lower bearing cover 33 The embodiment illustrated in FIG. 6, in which the same elements have the same references as in FIGS. 4 and 5, comprises a sliding element different from that illustrated in FIGS. 4 and 5. The sliding element 50 illustrated FIG. 3 is of generally toroidal shape with axis Y1 substantially coaxial with the vertical axis Y of the suspension stop device 30. The lower cover 33 comprises on its upper surface 40 a toroidal surface 51 in shape with the sliding element 50. The upper cover 32 also comprises on its lower surface 36b a toroidal surface 52 in shape with the sliding element 50. In longitudinal section following a plane containing the axis Y1, the sliding element 50 is of circular section. The invention is not limited to the described embodiments and may be subject to various variations. For example, sealing means can be mounted in all the examples described above. The sliding elements can be made, by way of non-limiting example, synthetic material such as polyamide PA 6.6, or polypropylene PP, or metal material from the same sheet blank. Lubrication can be carried out by applying a thin layer of PTFE polytetrafluoroethylene or a thin layer of greasy material. The self-lubricating sliding member is in full contact with the lower support cover and the upper support cover, thus reducing the number of elements forming the suspension stop device.

Such a suspension stop device makes it possible to reduce manufacturing costs by limiting the number of elements to be assembled. In addition, the conformation of the sliding elements with the lower and upper covers provides a suspension stop device capable of supporting the axial and radial forces exerted by the suspension spring and to obtain a suspension stop with good friction properties.

Claims (13)

REVENDICATIONS1. Suspension stop device (10, 30) for a motor vehicle comprising an upper cover (12, 32) intended to be mounted on the chassis of the motor vehicle, and a lower cover (13, 33) having a lower surface (19c, 39c ) forming a bearing surface for a suspension spring (11, 31) for exerting axial and radial forces on the suspension stop device (10, 30), characterized in that it comprises a self-lubricating element (15, 25, 35, 50) disposed between the upper cover (12, 32) and the lower sliding bearing cover (13, 33), said self-lubricating element (15, 25, 35, 50) being in contact over its entire surface with complementary surfaces (16c, 361), 20d, 40) of the upper cover (12, 32) and the lower cover (13, 33) and being able to take up the axial and radial forces exerted by the suspension spring (11, 31). 2. Stop device according to claim 1, characterized in that the self-lubricating element (15, 25) is frustoconical and comprises an upper surface (15a, 35a) in contact over its entire surface with a lower surface (16c) of the hood upper (12) and a lower surface (15b, 35b) in contact over its entire surface with an upper surface (20d) of the lower cover (13). 3. Stop device according to claim 2, characterized in that the self-lubricating element (15, 25) is made of fabric or glass fibers. 4. Stop device according to claim 2 or 3, characterized in that the self-lubricating element (15, 25) has a thickness of between 0.1 mm and 10 mm. Stop device according to claim 1, characterized in that the self-lubricating element (35) comprises two axial portions (41, 42) and two radial portions (43, 44), so as to form a self-lubricating element (35) presenting in cross section a profile in the form of a cross. Stop device according to claim 5, characterized in that each of the radial portions (43, 44) comprises an upper surface (43a, 44a) in contact on its entire surface with a lower surface (361)) of the upper cover ( 32) and a lower surface (431), 441)) in full contact with an upper surface (40) of the lower cover (33). 7. Stop device according to claim 5 or 6, characterized in that the axial portions (41, 42) extend axially opposite to each other relative to the radial portions (43, 44). 8. Stop device according to claim 7, characterized in that the upper cover (32) and the lower cover (33) each comprise a groove (45, 46) opening respectively on the upper surface (40) and the lower surface ( 36b), said grooves (45, 46) being shaped to cooperate with one of the axial portions (41, 42) of the self-lubricating element (35). 9. Stop device according to one of the preceding claims, characterized in that the self-lubricating element (15, 25, 35) is of constant thickness. 10. Suspension stop device according to claim 1, characterized in that the self-lubricating element (50) is of toroidal shape with axis (Y1) substantially coaxial with the vertical axis (Y) of the suspension stop device ( 30). Stop device according to one of the preceding claims, characterized in that the upper cover (12, 32) is provided with an annular outer skirt (17, 38) and / or an annular inner skirt (37). surrounding the lower cover (13, 33) and defining with the lower cover (13, 33) an annular passage (20c, 39b) forming a labyrinth seal. 12. Stop device according to claim 11, characterized in that at least one of the annular skirts (17, 37, 38) of the upper cover (12, 32) comprises a hook (17b, 37a) intended to cooperate with a hook ( 20a, 40a) corresponding to the lower cover (13, 33). 13. Suspension leg comprising a suspension stop device (10, 30) according to one of the preceding claims.