Brake pads with resin backing plate

Abstract

A backing plate (10) for a hydraulic brake of a motorcycle is made of a resin material and has a first surface (11) and a second surface (13) which are opposite surfaces. The first surface (11) is configured to fixedly support a layer of a friction material (8). An undercut recess (14) formed within a thickness (t) of the backing plate (10) opens to the second surface (13) and is configured to receive and hold a corresponding portion (17) of a floating piston (15) for actuating the brake. This is a brake pad with a resin backing plate.

Description

[Technical field]

[0001] The present invention relates to a brake pad having a backing plate of a resin material formed to provide a positive bond between the pad and a piston, particularly for use in motorcycles. [Background technology]

[0002] As is known, brake pads are conventionally manufactured with a plate-shaped metal backing plate having a surface on which a layer of friction material is fixedly applied. Brake pads with a backing plate of fiber-reinforced resin material are also known. See, for example, patent publications JP2013-057337A, JP2012-211675A, and EP1006289A2. Brake pads with a backing plate made of fiber-reinforced resin are highly valued for their light weight, high strength, and high moldability.

[0003] In many brakes, a pair of brake pads are associated with a spring clip adapted to move the brake pads away from the braking surface of the brake disc when hydraulic braking is terminated, thus reducing vibration and sliding of the brake pads against the surface of the disc.

[0004] US3720293A and GB1270364A each disclose a metallic backing plate for a vehicle hydraulic brake, the backing plate having two opposite surfaces, a first surface configured to fixedly carry a layer of friction material, and a second surface opposite the first surface. The backing plate has a notch and the friction material provides a groove which, together with the backing plate, forms an undercut recess which receives and retains a coupling head of a brake actuating piston.

[0005] JP2011-047430A and EP2472135A1 disclose brakes including pads connected to a backing plate of a non-resin material. The backing plate is in turn connected to a holder. One end of the holder has an opening which, together with the backing plate, forms an undercut for receiving an anchor pin. In particular, the undercut receives and holds the head of the anchor pin by the coupling between a groove provided in the anchor pin and the undercut formed by the coupling of the holder and the backing plate.

[0006] JP 2013-057337A discloses a brake pad with a backing plate made of a fiber-reinforced resin material. DISCLOSURE OF THEINVENTION

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to simplify disc brakes by eliminating the conventional spring clip elements for the brake pads.

[0008] The present invention proposes that the brake pads be kept in contact with the piston as much as possible by mechanical fixation in order to prevent the brake pads from vibrating and sliding against the disc when braking is stopped.

[0009] These and other objects and advantages, which will be better understood hereinafter, are achieved according to the present invention by a backing plate for brake pads having the features set forth in claim 1. Preferred embodiments of the invention are defined in the dependent claims.

[0010] According to one aspect of the invention, a backing plate for a hydraulic brake of a motorcycle is made of a resin material and has two opposite faces. The first face fixedly carries a layer of friction material. The second face is opposite the first face and defines a thickness thereof. At least one undercut recess formed within the thickness of the backing plate is open on the second face and configured to receive and retain a corresponding portion of at least one floating piston for actuating the brake.

[0011] According to another aspect, the present invention provides an assembly including a brake pad and at least one associated actuating floating piston.

[0012] According to a further aspect, the present invention provides a brake caliper comprising a caliper body and at least one assembly including a brake pad and at least one floating piston. [Brief description of the drawings]

[0013] [Figure 1] 1 is an exploded perspective view of a hydraulic brake according to an embodiment of the present invention; FIG. [Diagram 2] FIG. 2 is a perspective view of a backing plate of a brake pad according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a side view of the floating piston. [Figure 4] FIG. 2 is a cross-sectional view taken along the section indicated by AA in FIG. 1, showing the geometric connection between the brake pad and two floating pistons. [Diagram 5] 2 is an axial cross-sectional view of the hydraulic brake according to the section indicated by DD in FIG. 1; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The characteristics and advantages of the invention will become apparent from the following description, given by way of non-limiting example. With initial reference to Figure 1, an embodiment of a hydraulic brake according to the invention will be described in its normal operating condition. The hydraulic brake consists, in the example shown here, of a caliper body 12 known per se, provided with two brake pads 9, 9' and four floating pistons 15a, 15b, 15c, 15d.

[0015] The caliper body 12 defines a geometric vertical midplane, designated BB, perpendicular to the axis of rotation of the brake disc (not shown). Throughout this specification and the claims, positional or orientation terms and expressions such as "axial", "radial", "longitudinal" and the like should be construed relative to the geometric midplane BB.

[0016] The floating pistons 15a, 15b, 15c, 15d are housed in cylindrical seats 23, 23' formed in the brake caliper body 12 and arranged in pairs on opposite sides of the central plane BB. The two pairs of cylindrical seats are axially aligned and spaced apart to accommodate the respective floating pistons, which, in use, act in pairs on one side of two brake pads arranged opposite one of two braking surfaces on opposing faces of the brake disc.

[0017] The general layout of a hydraulic brake as shown in Figure 1 is believed to be generally known, and therefore in the following description only those elements of particular importance and interest for carrying out the present invention will be described in detail.

[0018] Each brake pad 9, 9' comprises a backing plate 10 and a layer of friction material 8, 8'.

[0019] The backing plate 10 is made of a resin material, preferably a resin material having high mechanical strength and high temperature resistance, such as polypropylene (PP), polyamide (6,66), polyester (PET), polyphthalamide (PPA), polyphenylsulfide (PPS), petroleum ester ketone (PEEK), etc.

[0020] Preferably, the resin material is reinforced with fibers, for example glass fibers, carbon fibers, aramid fibers, synthetic aramid fibers (Kevlar®). The brake pads 9, 9' are housed in the caliper body 12 with their respective friction materials facing the central geometric plane BB. During braking, the floating pistons 15a-15d bias the brake pads 9, 9' in opposite axial directions against the opposite faces of the brake disc (not shown).

[0021] 2, the backing plate 10 has two opposing sides, a first side 11 of which is configured to fixedly carry (typically by bonding or molding) a layer of friction material 8, 8', and a second side 13 opposite the first side. The second side 13 together with the first side 11 defines a thickness t.

[0022] Formed within the thickness t of the backing plate are at least one undercut recess, in this example two undercut recesses 14, 14', which open onto the second face 13 of the backing plate 10 and are configured to receive and retain corresponding portions of respective floating pistons 15 which extend to urge the pads against the brake disc when the brakes are actuated.

[0023] In an embodiment, the undercut recesses 14, 14' extend through the entire thickness t of the backing plate 10 (FIG. 2), such that the recesses are also open on the first surface 11 of the backing plate.

[0024] In the exemplary embodiment shown in FIG. 2, the undercut recesses 14, 14' advantageously define seats having a symmetrical shape with respect to a vertical plane of symmetry CC (FIG. 2) perpendicular to the second face 13 of the backing plate 10.

[0025] Preferably, each undercut recess 14 , 14 ′ has an insertion opening 16 , 16 ′ that opens into a side edge 25 of the backing plate 10 .

[0026] In the embodiment of FIG. 2, the backing plate has two undercut recesses 14, 14' horizontally spaced apart and configured to receive and retain a portion of each floating piston 15 through insertion openings 16, 16'.

[0027] Referring to FIG. 3, the floating piston 15 has a cylindrical side surface 18 and an integral coupling head 17 integrally protruding from one face of the piston and having an enlarged end having a shape and size that at least partially corresponds or matches the shape and size of one of the respective undercut recesses 14, 14' presented by the backing plate 10.

[0028] The coupling head 17 of the floating piston 15 is intended to provide a positive connection between the backing plate 10 of the brake pad 9 and the floating piston 15 (FIG. 4).

[0029] Preferably, the coupling head 17 has an axially symmetric shape that corresponds to the shape and size of the undercut recess that receives it. In the embodiment illustrated here, the coupling head 17 has a T-shape (FIG. 3).

[0030] Within the undercut recesses 14, 14' the backing plate 10 defines at least one engagement surface 19 facing away from the second surface 13. The engagement surface 19 serves as a gripping surface for the piston coupling head 17 to pull the brake pads 9, 9' away from the brake disc when braking is terminated.

[0031] The sizes of the undercut recesses in the backing plate and the mating head of the floating piston described and illustrated herein are not considered limiting to the practice of the present invention.

[0032] The embodiment in which the undercut recesses 14, 14' extend through the entire thickness t of the backing plate 10 (FIG. 2) and thereby open to the first face 11 and the second face 13 of the backing plate facilitates the assembly step in which the coupling head 7 of the floating piston is inserted into the insertion opening 16 of the backing plate.

[0033] Preferably, to facilitate assembly, there may be some axial clearance between the coupling head 17 of the floating piston and the layer of friction material 8 in the assembled condition (FIG. 4).

[0034] Advantageously, the layer 8, 8' of friction material can be manufactured as a solid block without forming any recesses or grooves therein.

[0035] Referring to FIG. 5, the floating piston 15 is axially movably received within a cylindrical seat 23, 23' of the caliper body 12 such that the cylindrical side surface 18 of the piston is substantially coaxially parallel to the inner cylindrical surface 20 of the seat formed by the caliper body 12.

[0036] According to an embodiment, the or each floating piston is maintained in said position by at least one annular seal 21, 21' of elastic material inserted in a circumferential groove 22, 22' formed by a seat 23, 23' in the caliper body 12.

[0037] Preferably, the annular seals 21, 21' are sized to be radially compressed between the cylindrical side surface 18 of the piston and the bottom surface of the grooves 22, 22'.

[0038] Operation of the preferred embodiment is as follows: When the hydraulic disc brake is actuated, the piston 15 is urged axially from a starting position towards the central geometric plane BB (and towards the brake disc, not shown), thereby elastically deforming the annular seals 21, 21' which are compressed between the cylindrical side surface 18 of the piston 15 and the bottom surfaces of the grooves 22, 22'. At the same time, the piston 15 pushes the brake pad 9 axially towards one face of the brake disc, exerting a braking torque. When the braking action is terminated, the elastic annular seals 21, 21' return to their initial undeformed state, returning the piston to its starting retracted position.

[0039] The mechanical positive lock between the coupling head 17 of the piston 15 and the undercut recesses 14, 14' of the backing plate 10 causes the brake pads to move away from the disc by the elastic return of the annular seal, i.e. to be pulled away from the disc. In the absence of braking action, the positive lock keeps the brake pads in contact with the piston as much as possible to avoid vibrations and sliding of the brake pads against the disc.

[0040] Although specific embodiments of the present invention have been disclosed, it is to be understood that such disclosure is for illustrative purposes only and that the present invention is not to be construed as being limited thereby. It will be apparent to those skilled in the art that various modifications can be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A backing plate (10) made of a resin material for a hydraulic brake of a motorcycle, comprising: The backing plate comprises: a first surface (11) configured to fixedly carry a layer (8, 8') of friction material; a second surface (13) opposite the first surface and defining a thickness (t); and having two opposite faces according to A backing plate (10) having at least one undercut recess (14, 14') formed within a thickness (t) of the backing plate (10), the undercut recess (14, 14') opening onto a second surface (13) and configured to receive and retain a corresponding portion (17) of at least one floating piston (15) for actuating a brake.

2. The backing plate (10) of claim 1, wherein the undercut recess (14, 14') has a symmetrical shape with respect to a plane of symmetry (CC) perpendicular to the second face (13) of the backing plate (10).

3. 2. The backing plate (10) of claim 1, wherein the undercut recess (14, 14') has an insertion opening (16, 16') for a floating piston (15) formed in a lateral edge (25) of the backing plate (10).

4. 2. The backing plate (10) according to claim 1, made of a resin material having high mechanical strength and high resistance at high temperatures selected from the group consisting of polypropylene (PP), polyamide 6, polyamide 66, polyester (PET, PBT), polyphthalamide (PPA), polyphenylsulfide (PPS), polyetheretherketone (PEEK).

5. 5. The backing plate (10) of claim 4, wherein the resin material is preferably fiber reinforced.

6. 2. The backing plate (10) of claim 1, wherein at least one undercut recess (14, 14') extends through the entire thickness (t) of the backing plate (10), whereby the undercut recess (14, 14') is also open on the first surface (11) of the backing plate.

7. 2. The backing plate (10) of claim 1, wherein the backing plate (10) defines at least one engagement surface (19) within the undercut recess (14, 14') facing away from the second surface (13).

8. An assembly comprising a brake pad (9) and at least one associated actuating floating piston (15), A brake pad (9) comprising a backing plate (10) according to any one of claims 1 to 7 and a layer (8, 8') of friction material arranged on a first surface (11) of the backing plate (10), at least one floating piston (15) having a cylindrical side surface (18) and a coupling head (17) having a shape and size that at least partially corresponds to the shape and size of the undercut recess (14, 14') on the second surface (13) of the backing plate (10); This provides a mechanical and geometric connection between the brake pad (9) and the floating piston (15).

9. Assembly according to claim 8, in which the layer (8, 8') of friction material is a solid block without any recesses or grooves.

10. An assembly according to claim 8; a caliper body (12) defining at least two cylindrical seats (23, 23') axially aligned and spaced apart with respect to a central geometric plane (BB) and adapted to receive two respective floating pistons (15); Equipped with each cylindrical seat (23, 23') having a circumferential groove (22, 22') housing an annular seal (21, 21') of elastic material and being radially compressed between a bottom surface of the circumferential groove (22, 22') and a cylindrical lateral surface (18) of the respective floating piston (15); Thereby, the annular seal (21, 21') causes the brake pads (9) to move away from the central geometric plane (BB) in the absence of braking action.

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