WO2004094857A1

WO2004094857A1 - Pad for a disc brake

Info

Publication number: WO2004094857A1
Application number: PCT/IT2003/000258
Authority: WO
Inventors: Fabiano Carminati; Marco Nervosi
Original assignee: Freni Brembo S.P.A.
Priority date: 2003-04-24
Filing date: 2003-04-24
Publication date: 2004-11-04
Also published as: AU2003230225A1; ITMI20040806A1

Abstract

A pad (1) for a disc brake comprises a plate (2) which has at least one groove (22a) in the rear surface on which the piston act and at least one rib (24a) on the front surface (7) which supports the friction material (4). The groove and the rib are formed by drawing and therefore have an identical shape. The grooves and the ribs confer on the plate a particularly rigid behaviour during braking which is particularly advantageous in pads of marked length.

Description

DESCRIPTION "PAD FOR A DISC BRAKE" [001] The subject of the present invention is a pad for a disc brake. [002] It is known that, during braking, the pad is subjected to a force due to the friction material being brought into abutment with the braking band of the disc and, at the same time, to the force of the piston which acts on the pad, bringing it into abutment with the braking band, so that the pad undergoes deformation. This deformation leads, for example, to non-uniform wear of the friction material.

[003] There is therefore a need to provide pads for disc brakes which display limited structural deformation during braking; this can help to ensure, for example, uniform wear of the friction material.

[004] The problem underlying the present invention is that of devising a disc-brake pad which has structural and functional characteristics such as to satisfy the above-mentioned needs and at the same time to overcome the disadvantages mentioned with reference to the prior art.

[005] This problem is solved by a pad according to Claim 1. The dependent claims describe further variants of the pad according to the invention. [006] The characteristics and the advantages of the pad will become clear from the following description of a preferred and non-limiting embodiment thereof, in which:

[007] Figures la and lb are a front and a rear axonometric view, respectively, of an embodiment of the pad according to the invention,

[008] Figures lc and Id are a front end view and a rear end view of the pad of Figure la, respectively, [009] Figure le is a side view of the pad of Figure lc, taken in the direction of observation indicated by the arrow A in Figure lc,

[0010] Figure If is a partially-sectioned side view of the pad of Figure lc, taken on the section line C-C of Figure lc and in the direction of observation indicated by the arrow B in Figure lc,

[0011] Figure lg is a view of the pad of Figure lc, taken in the direction of observation indicated by the arrow D in Figure lc, [0012] Figures 2a and 2b are a front and a rear axonometric view, respectively, of a further embodiment of the pad according to the invention,

[0013] Figures 2c and 2d are a front end view and a rear end view of the pad of Figure 2a, respectively, [0014] Figure 2e is a side view of the pad of Figure 2c, taken in the direction of observation indicated by the arrow A in Figure 2c,

[0015] Figure 2f is a partially-sectioned side view of the pad of Figure 2c, taken on the section line C-C of Figure 2c and in the direction of observation indicated by the arrow B in Figure 2c,

[0016] Figures 3a and 3b are a front and a rear axonometric view, respectively, of a further embodiment of the pad according to the invention, [0017] Figures 3c and 3d are a front end view and a rear end view of the pad of Figure 3a, respectively,

[0018] Figure 3e is a side view of the pad of Figure 3c, taken in the direction of observation indicated by the arrow A in Figure 3c, and [0019] Figure 3f is a partially-sectioned side view of the pad of Figure 3c, taken on the section line C-C of Figure 3c and in the direction of observation indicated by the arrow B in Figure 3c.

[0020] With reference to the appended drawings, a pad according to the invention is generally indicated 1. [0021] The pad 1 can be associated with a caliper (not shown) comprising a caliper body fixed firmly to a fixed portion of the vehicle chassis and provided with thrust means suitable for acting on the pad in order to bring it into abutment with a braking band of a brake disc during braking . [0022] The pad 1 comprises a plate 2 and friction material 4.

[0023] The plate 2 has working surfaces suitable for interacting with the thrust means and with the friction material.

[0024] In particular, the working surfaces comprise a rear surface 6 suitable for being acted on by the thrust means during breaking in order to bring the friction material into abutment with the braking band of the brake disc, and a front surface 7 for supporting the friction material 4.

[0025] Moreover the plate 2 has a first side 8 and a second side 10, opposite the first.

[0026] The first side 8 and the second side 10 are spaced apart so as to define the extent of the plate 2 in a longitudinal direction.

[0027] The first side 8 is preferably parallel to the second side 10.

[0028] In a preferred embodiment of the pad, the first side 8 and/or the second side 10 form reaction sides for the pad 1.

[0029] The reaction sides are suitable for cooperating with respective reaction ribs of the caliper body in order to transmit the braking force which is generated during braking to the caliper body. [0030] In one embodiment of the pad 1, the first side 8 and the second side 10 form reaction sides (Figures lc and Id) .

[0031] In further embodiments of the pad 1, the first side 8 has a reaction portion 8a which preferably lies in a plane and which forms a reaction side (Figures 2d and 3d) .

[0032] The sides 8, 10 of the plate 2 are connected to an outer edge surface 12 and to an inner edge surface 14 opposite the outer edge surface .

[0033] The outer edge surface 12 and the inner edge surface 14 are spaced apart and delimit the plate 2 transversely.

[0034] In a preferred embodiment, the outer edge surface may be shaped in a manner such that the plate 2 has projections 16 and respective recesses.

[0035] The projections and the recesses constitute a preferred embodiment of retaining means suitable for cooperating with resilient elements such as springs and the like to hold the pad suitably housed in the caliper body.

[0036] In a further embodiment, the plate has, in the region of the upper edge surface 12, a projection 18 provided with an eye 20. [0037] In one embodiment, the projection and the eye constitute means for the suspension of the pad 1 on the caliper body in which it can be housed. For example, the eye 20 is suitable for cooperating with a suspension pin of the caliper body. [0038] In further embodiments, the projection 18 and the eye 20 constitute suspension means and at the same time reaction means, suitable for suspending the pad 1 on the caliper body and at the same time for transmitting the braking force which is generated by the friction material 4 during braking to the caliper body.

[0039] The plate 2 has at least one groove in a first of the working surfaces 6, 7 and at least one rib projecting from the opposite working surface 7, 6. [0040] In other words, the plate 2 has at least one groove in one working surface, for example, in the rear surface 6, and one rib on the opposite working surface, that is, on the front surface 7, in this example. [0041] In a preferred embodiment, the plate 2 has a first groove 22a and a second groove 22b in the rear surface 6 and a first rib 24a and a second rib 24b projecting from the front surface 7.

[0042] According to a variant, the grooves 22a, 22b extend in a corresponding manner to the ribs 24a, 24b. [0043] In other words, each groove 22a, 22b extends along a path, defined as the axis of the groove, which is identical to the path along which the respective rib 24a, 24b extends.

[0044] According to a further embodiment, the grooves 22a, 22b and the respective ribs 24a, 24b are produced by a drawing process which leads to the formation, for example, of the grooves 22a, "22b in the rear surface 6 of the plate 2 and, at the same time, of the respective ribs 24a, 24b on the front surface 7 of the plate. [0045] The grooves and the ribs advantageously help to give the plate more rigid behaviour .

[0046] In other words, the presence of the grooves and of the ribs, which maintain a uniform thickness of the plate since they are produced by drawing, confer on the cross- section of the plate, taken in a plane perpendicular to the longitudinal direction, an axis which is not straight but, for example, is curved or formed by an interrupted line.

[0047] This configuration, which is advantageously produced by drawing, has exhibited an increase in the stiffness of the plate that is subjected to the braking stresses.

[0048] According to a variant, the groove 22a, 22b extends along a path constituted by an open line, for example, a segment of a line. [0049] In a further variant, the path is constituted by an open curved line.

[0050] According to a preferred embodiment, the groove 22a, 22b extends along a path which extends between the first side 8 and the second side 10 of the plate 2 (Figure 2b) .

[0051] According to a further variant, the groove 22a, 22b extends between the outer edge surface 12 and the inner edge surface 14 of the plate . [0052] In yet another embodiment, the groove 22a, 22b has a path which extends between the first side 8 or the second side 10 and the inner edge surface 14 or the outer edge surface 12, preferably with crossed grooves (Figure lb) . [0053] In particular, according to this embodiment, if a central plane X-X is defined for the plate, the central plane being perpendicular to the longitudinal direction, the groove 22a, 22b has a path which extends between the first side 8 or the second side 10 and the inner edge surface 14 or the outer edge surface 12, on the side of the central plane remote from the said first or second side.

[0054] In a further embodiment, the grooves 22a, 22b extend along substantially parallel paths (Figure 2b) . [0055] In yet another embodiment, the grooves 22a, 22b extend along substantially parallel and substantially straight paths (Figure 3b) .

[0056] The ribs 24a, 24b projecting from the front surface 7 of the plate 2 have a shape corresponding to that described for the grooves . [0057] In a variant, the plate 2 has at least one through-hole between the front surface 7 and the rear surface 6.

[0058] The plate 2 preferably has a first hole 26a and a second hole 26b. [0059] The holes 26a, 26b are preferably at least partially filled with the friction material 4 of the pad

1.

[0060] When the disc brake is in a mounted configuration, the pad 1 is housed in a suitable housing provided in the caliper body.

[0061] The pad 1 is housed in a manner such that the rear surface 6 can be acted on by the thrust means . In other words, the rear surface faces towards the piston or pistons of the thrust means. [0062] The front surface 7 of the plate 2 which supports the friction material 4 faces towards the braking band of the disc.

[0063] The pad is kept in position by the suspension means, that is, by means of the eye 20 which cooperates with a pin of the caliper body. [0064] According to a variant, the pad 1 is supported in the region of a bearing portion which is provided on the inner edge surface 14 and which is placed in contact with a support element provided in the caliper body. [0065] During the normal operation of the disc brake, the user pressurizes the brake fluid contained in the hydraulic circuit of the disc brake, for example, by acting on the operating lever of a master cylinder with a hand or with a foot. [0066] The fluid under pressure causes the pistons or piston of the caliper body to advance towards the braking band of the disc, urging the pad 1 towards the braking band.

[0067] The friction material 4 comes into contact with the braking band and generates a braking force which is transmitted to the caliper body that is fixed firmly to a fixed portion of the vehicle chassis.

[0068] During braking, the plate is subjected, amongst other things, to the force due to the pad being brought into abutment with the braking band and to the action of at least one piston which acts on the pad, urging it towards the braking band.

[0069] In particular, the force due to the friction material being brought into abutment with the braking band is distributed substantially over the outer surface of the friction material, whereas the action of the piston is concentrated on a portion of the rear surface of the plate.

[0070] Unusually, the grooves and the ribs provided in the plate confer on the plate a behaviour during braking that is characterized by limited structural deformation. [0071] In contrast with what occurs in pads of the prior art, these forces do not lead. to a deformation of the plate which could result in a misalignment of the friction material supported thereby relative to the braking band of the disc .

[0072] Furthermore, this phenomenon is not translated into non-uniform wear of the friction material, even in plates of marked length, for example, plates which differ from a substantially square shape by virtue of their length.

[0073] Moreover, this phenomenon does not arise in pads which are suitable for cooperating with two or more pistons and which are therefore of considerable length. [0074] Furthermore, for a groove in one working surface, there is a corresponding rib on the opposite surface, so that a substantially uniform thickness of the plate is maintained.

[0075] In other words, the configuration avoids the presence of thinner portions of the plate. [0076] Moreover, the grooves and the corresponding ribs are advantageously produced easily and quickly by drawing, without wastage of material.

[0077] According to a further advantageous aspect, the grooves are produced in the rear surface of the plate and are not covered by the friction material so that they are visible in the package or in the maintenance kit with which they are marketed. [0078] This confers on the pad a sporty and pleasing appearance which attracts the interest of an enthusiast.

[0079] According to yet another advantageous aspect, the projection relative to the front surface of the rib, at least partially covered by the friction material, represents an aid for the user during maintenance of the disc brake, to indicate the useful thickness of friction material .

[0080] Finally, according to a further advantageous aspect, the grooves in the rear surface of the plate form channels for venting the air contained in the pistons. [0081] In other words, the air contained inside the pistons, which are generally hollow, undergoes strong heating as a result of the braking action, and therefore considerable expansion. In spite of the fact that the piston is in abutment with the rear plate surface during braking, this air advantageously escapes through the grooves .

[0082] Naturally, in order to satisfy contingent and specific requirements, a person skilled in the art will be able to apply to the above-described disc-brake pad many modifications and variations all of which, however, are included within the scope of protection of the invention as defined by the appended claims.

Claims

1. A pad (1) for a disc brake, to be associated with a caliper provided with thrust means suitable for acting on the pad in order to bring it into abutment with a braking band of a brake disc during braking, in which the pad comprises a plate (2) which has working surfaces (6, 7) comprising a rear surface (6) suitable for being acted on by the thrust means, and a front surface (7) for supporting friction material, in which the plate (2) has at least one groove (22a, 22b) in a first of the working surfaces (6, 7) and at least one rib (24a, 24b) projecting from the opposite working surface (7, 6) .

2. A pad (1) according to Claim 1, in which the groove (22a, 22b) in the first working surface extends in a corresponding manner to the rib (24a, 24b) on the opposite working surface.

3. A pad (1) according to Claim 1 or Claim 2, in which the groove (22a, 22b) in the first working surface extends along a path identical to the path along which the rib (24a, 24b) on the opposite working surface extends .

4. A pad (1) according to any one of the preceding claims, in which the groove (22a, 22b) and the rib (24a, 24b) are produced simultaneously by means of a drawing process performed on the plate (2) .

5. A pad (1) according to any one of the preceding claims, in which the plate (2) has a substantially uniform thickness .

6. A pad (1) according to any one of the preceding claims, in which the groove (22a, 22b) extends along a path formed by an open line.

7. A pad (1) according to any one of the preceding claims, in which the plate (2) comprises a first side (8) and a second side (10) opposite the first, which sides delimit the plate (2) longitudinally, and the plate (2) comprises an outer edge surface (12) and an inner edge surface (14) opposite the outer edge surface, which surfaces delimit the plate (2) transversely.

8. A pad (1) according to Claim 7, in which the groove (22a, 22b) extends along a path which extends between the first side (8) and the second side (10) .

9. A pad (1) according to Claim 7 or Claim 8, in which the groove (22a, 22b) follows a path which extends between the outer edge surface (12) and the inner edge surface (14) .

10. A pad (1) according to Claim 7, in which the groove (22a, 22b) has a path which extends between one of the sides (8, 10) and one of the edge surfaces (12, 14) of the plate (2) .

11. A pad (1) according to Claim 10, in which the groove (22a, 22b) has a path which extends between one of the sides (8, 10) and one of the edge surfaces (12, 13) of the plate (2) on the side of the central plane (X-X) remote from the said side (8, 10) of the plate (2) .

12. A pad (1) according to any one of the preceding claims, in which the first working surface has two crossed grooves .

13. A pad (1) according to any one of Claims 1 to 11, in which the first working sur ace has two parallel grooves .

14. A pad (1) according to any one of the preceding claims in which the groove is formed in the rear surface (6) of the plate (2) .

15. A pad (1) according to any one of the preceding claims, in which the groove (22a, 22b) extends along a path formed by a closed line.

16. A pad (1) according to any one of the preceding claims in which the plate (2) has at least one hole (26a, 26b) .

17. A pad (1) according to Claim 16, in which the hole is a through-hole extending between the working surfaces (6, 7).

18. A pad (1) according to Claim 16 or Claim 17, in which the hole (26a, 26b) is at least partially filled with the friction material (4) .

19. A pad (1) according to any one of the preceding claims, in which the groove (22a, 22b) formed in the rear surface (6) of the plate (2) forms means for venting air contained in cavities of pistons of thrust means.

20. A pad (1) according to Claim 19, in which the groove (22a, 22b) forms channels for venting the air contained in the cavities of the pistons of the thrust means.

21. A maintenance kit comprising at least one pad (1) according to any one of the preceding claims .

22. A disc-brake caliper suitable for housing a pad (1) according to any one of Claims 1 to 20.

23. A caliper according to Claim 22, comprising pad thrust means comprising two or more pistons arranged to act on the pad.

24. A disc brake comprising a caliper according to Claim 22 or Claim 23.

25. A method for the production of a plate (2) of a discbrake pad (1) , comprising the step of performing a drawing operation in order to produce at least one groove (22a, 22b) in a first working surface (6, 7) of the plate (2) and at least one corresponding rib (24a, 24b) on the opposite working surface (7, 6) .

26. A production method according to Claim 25, in which the first working surface is a rear surface (6) of the plate (2) suitable for cooperating with thrust means of the disc brake .