Braking device

Abstract

This braking device comprises a seal (1) having a first sealing part (2) made of a first material and a second sealing part (4) made of a second material different than the first material. In addition, the first material comprises PTFE, the second material comprises EPDM, and the first sealing part (2) and the second sealing part (4) are adhesively bonded together.

Claims

1. A braking device for a motor vehicle, the braking device comprising a seal, wherein the seal comprises a first sealing part made of a first material and a second sealing part made of a second material different than the first material, wherein the first material comprises PTFE and the second material comprises EPDM, and wherein the first sealing part and the second sealing part are adhesively bonded together; wherein the first sealing part has a contacting surface in contact with and sealing an ABS piston of the braking device; and an ABS pump having a wall in contact with the second sealing part and a piston in contact with the first sealing part.

2. The braking device as claimed in claim 1, wherein the second sealing part has a second contacting surface, the contacting surface of the first part having a concave portion and the second contacting surface having a convex portion with a shape complementary to the concave portion.

3. The braking device as claimed in claim 1, wherein the first sealing part and the second sealing part are annular and arranged in a radial stack.

4. The braking device as claimed in claim 1, wherein the first sealing part and the second sealing part include contacting surfaces to delimit one or more chicanes.

5. The braking device as claimed in claim 1, wherein the first sealing part and the second sealing part are adhesively bonded together with a glue, and wherein the glue bonding the first sealing part and the second sealing part each comprise a primer coating suitable for adhering to the first material and a secondary coating suitable for adhering to the primer coating and to the second material.

6. The braking device as claimed in claim 1, wherein the first sealing part and the second sealing part are adhesively bonded together with a glue, and wherein the glue bonding the first sealing part and the second sealing part extends only over contacting surfaces of the first and second sealing parts.

7. The braking device as claimed in claim 1, wherein the first sealing part and the second sealing part are adhesively bonded together with a glue, and wherein the glue bonding the first sealing part and the second sealing part extends over the entire surface area of the first and second sealing parts.

8. The braking device as claimed in claim 1, wherein the first material comprises a carbon filler.

9. The braking device as claimed in claim 1, wherein the second sealing part comprises an annular slot formed in a transverse face of this second sealing part.

10. The braking device of claim 1, wherein the second sealing part has a second contact surface to bear against an inner wall of a casing of a pump of the braking device.

11. The braking device of claim 1, wherein the second sealing part is arranged within the first part.

12. The braking device of claim 1, wherein the second sealing part has an elasticity selected based on fitting within an ABS pump and to withstand high pressure leaks.

13. A braking device for a motor vehicle, the braking device comprising a seal, wherein the seal comprises a first sealing part made of a first material and a second sealing part made of a second material different than the first material, wherein the first material comprises PTFE and the second material comprises EPDM, and wherein the first sealing part and the second sealing part are adhesively bonded together; wherein the first sealing part has a contacting surface in contact with and sealing an ABS piston of the braking device; and wherein the second sealing part includes a slot portion and an annular lip portion to apply radial pressure to the first sealing part in the event of high pressure between the slot portion and the first sealing part.

14. The braking device of claim 13, wherein the slot portion is U shaped.

15. The braking device of claim 14, wherein the first sealing part has a radial groove.

Description

(1) Further features and advantages of the present invention will become clearly apparent from the following detailed description of an embodiment, given by way of nonlimiting example, with reference to the appended drawings, in which:

(2) FIG. 1 is a view in partial section of a pump of an ABS braking device of the prior art, showing a conventional piston seal,

(3) FIG. 2 is a perspective sectional view of a seal of a braking device according to one embodiment of the invention,

(4) FIG. 3 is a sectional side view of a seal of a braking device according to one embodiment of the invention.

(5) FIGS. 2 and 3 show a seal 1 of a braking device according to one embodiment of the invention. The braking device is a braking device for a motor vehicle, preferably of the anti-lock braking system (ABS) type.

(6) The seal 1 of the braking device according to the invention is intended to seal a component of the braking device which is in contact with a brake fluid. The brake fluid may be a brake fluid of the DOT type. The seal 1 is thus suitable for use with this type of brake fluid.

(7) Preferably, the braking device comprises the seal 1 and a pump element around which the seal 1 extends. Thus, the seal 1 is intended to provide sealing at this pump element, which may be the piston of a pump of the braking device, notably by replacing the piston seal 300 shown in FIG. 1. In particular, the seal 1 is configured to provide sealing between this pump element and a casing of the pump.

(8) The seal 1 is a composite seal comprising a first sealing part 2 made of a first material and a second sealing part 4 made of a second material. The first sealing part 2 and the second sealing part 4 are fastened together by adhesive bonding. The first sealing part 2 and the second sealing part 4 are thus secured together by means of a glue or binder. Therefore, the two sealing parts 2, 4 form a single component.

(9) The first sealing part 2 is intended to bear against the pump element, while the second sealing part 4 is intended to bear against an inner wall of a casing of the pump. The seal 1 is thus intended to be interposed between the piston and the casing of a pump of an ABS device.

(10) The first sealing part 2 is made of a first material based on polytetrafluoroethylene (PTFE), so as to provide dynamic sealing and to give the seal 1 wear resistance. In addition, the first material can advantageously comprise carbon fillers.

(11) The second sealing part 4 is made of a second material which is an elastomer based on ethylene propylene diene monomer (EPDM), so as to provide the seal 1 with a degree of elasticity, thereby allowing the latter to deform while it is being fitted in an ABS pump and to withstand high pressure peaks.

(12) As shown in FIGS. 2 and 3, the seal 1 advantageously has an annular shape. The seal 1 delimits an opening 6 through which the pump element is intended to extend.

(13) The first sealing part 2 and the second sealing part 4 in this case have an annular shape. The first sealing part 2 and the second sealing part 4 can be arranged, as illustrated in FIGS. 2 and 3, in a radial stack; that is to say that the sealing parts 2, 4 form two concentric rings alongside one another, one being enclosed in the other.

(14) Advantageously, the first sealing part 2 that is intended to provide dynamic sealing is arranged inside the second sealing part 4 that is intended to provide static sealing. Thus, the first sealing part 2 advantageously forms the internal part of the seal 1 while the second sealing part 4 forms the external part.

(15) In particular, the seal 1 can extend around an ABS pump piston, the first sealing part 2 being in contact with the piston and the second sealing part 4 being in contact with the casing of the pump. This makes it possible to protect an electric drive motor of the ABS pump effectively and with a long lifetime, and to prevent leakage of the brake fluid.

(16) Although not shown, the second sealing part 4 could, conversely, be arranged inside the first sealing part 2. The second sealing part 4 would then form the internal part of the seal 1 while the first sealing part 2 would form the external part. This may be the case for a seal 1 positioned for example in a groove of the piston, the dynamic sealing then needing to be ensured in the external part.

(17) As indicated above, the seal 1 comprises a binder or glue interposed between the first and the second sealing part 2, 4 so as to bond them together.

(18) In order to ensure effective fastening of the first sealing part 2 and the second sealing part 4, and thus to contribute towards an improved lifetime of the seal 1, the glue advantageously comprises a first layer, or primer coating, suitable for adhering to the material of the first sealing part 2, and preferably a second layer, or secondary coating, suitable for adhering to the primer coating and to the second sealing part 4.

(19) The glue is advantageously suitable for securing elastomeric materials. The glue used may be a water-based glue. Preferably, the glue comprises a primer coating having one or more elements selected from a phenolic resin, a halogenated polymer, and an organic solvent comprising xylene and/or methyl isobutyl ketone (MIBK). If need be, the glue can comprise a secondary coating preferably having one or more elements selected from chlorosulfonated polyethylene, a halogenated polymer and xylene. By way of nonlimiting example, the glue can be a LORD Chemosil 211 binder for the primer coating and a Chemosil NL 411 binder for the secondary coating or more generally any other glue suitable for securing EPDM and PTFE.

(20) The first sealing part 2 and the second sealing part 4 each have a contacting surface 8, 10. The contacting surface 8 is formed for example on an external wall of the first part 2, while the contacting surface 10 is formed for example on an internal wall of the second sealing part 4. The contacting surface 8 of the first sealing part 2 is positioned in a manner bearing against the contacting surface 10 of the second sealing part 4.

(21) The glue extends between these contacting surfaces 8, 10, and preferably only between the contacting surfaces 8, 10. According to one advantageous possibility, the glue extends over the entire surface area of the contacting surfaces 8, 10.

(22) As can be seen in FIGS. 2 and 3, the contacting surfaces 8, 10 have complementary shapes. Thus, the contacting surfaces 8, 10 are intended to be interlocked.

(23) In particular, one of these surfaces, for example the contacting surface 8 of the first sealing part 2, has a concave portion 12, and the other of these surfaces, such as the contacting surface 10 of the second sealing part 4, has a convex portion 14 with a complementary shape to the concave portion 12.

(24) Thus, the second sealing part 4 can have a radial protrusion or slot that is intended to interlock with a cavity or groove of the first sealing part 2.

(25) The contacting surface 8 can occupy any external face of the first sealing part 2. The contacting surface 10 can occupy any internal face of the second sealing part 4.

(26) If need be, the first sealing part 2 and the second sealing part 4 can have one or more coplanar transverse faces 24.

(27) The second sealing part 4 advantageously comprises an annular slot or groove 26 formed on one side of the second sealing part 4, and more particularly on at least one transverse end face 24 of the latter. This slot 26 is preferably U-shaped or V-shaped.

(28) An annular lip portion 27 which is intended to apply radial pressure to the first sealing part 2 in the event of high pressure thus extends between the slot 26 and the first sealing part 2.

(29) In other words, the pressure exerted by this lip portion 27 on the first sealing part 2 is slaved to the pressure in the braking device.

(30) An internal wall of the first sealing part 2 can have a radial groove 28.

(31) In addition, it will be noted that the intersecting lines 30 of the lateral faces 24 of the first sealing part 2 and of the second sealing part 4 have a radial offset; that is to say that one of them is closer to a central axis A than the other of these two intersecting lines. This provides an increase in resistance over time to repetitive axial loads.

(32) Furthermore, the contacting surfaces 8, 10 can advantageously be shaped to delimit one or more chicanes 16. For example, each contacting surface 8, 10 can comprise two or three adjacent, consecutive inclined faces 18, 20, 22. Preferably, the chicane(s) 16 is/are arranged at the edge of the contacting surfaces 8,10 so as to further protect a central zone of the contacting surfaces 8, 10 from the outside environment.

(33) Of course, the invention is in no way limited to the embodiment described above, this embodiment only having been given by way of example. Modifications are possible, notably from the point of view of the makeup of the various elements or by the substitution of technical equivalents, without otherwise departing from the scope of protection of the invention.