Sliding guide for a disc brake of the floating caliper type

Abstract

A sliding guide (15) for a disc brake (1) of the floating-caliper type comprises: a) a guide pin (16) forming a cylindrical guide portion (17) defining a guide axis (18) and a fixing portion (19) for fixing the guide pin (16) to a support bracket (2) or to a caliper body (5) of the disc brake (1), b) a floating body (20) forming a tubular cylindrical sliding portion (21 ) and a first spring seat (22), c) a return spring (23), d) one or more friction elements (24), e) a guide seat (25) formed in or connectable to the caliper body (5) or to the support bracket (2), and forming a guide hole (26), preferably cylindrical, f) a second spring seat (27) formed by the guide seat (25) formed in or connectable to the caliper body (5), or formed in or connectable to the support bracket (2), wherein the tubular sliding portion (21) is slidably fitted onto the guide portion (17), the friction element (24) is interposed between the guide portion (17) and the sliding portion (21), the sliding portion (21) is slidably inserted into the guide hole (26), the first (22) and second (27) spring seats face each other in the direction of the guide axis (18), and the return spring (23) is connected between the first spring seat (22) and the second spring seat (27) so as to be elastically deformable in the direction of the guide axis (18).

Description

“Sliding guide for a disc brake of the floating caliper type”

[0001] Field of the invention

[0002] The present invention relates to a floating disc brake, particularly for motor vehicles, of the type comprising a support bracket connectable to the vehicle suspension, a caliper body slidably mounted to the support bracket and forming a first wall arranged on a first side of a brake disc and a second wall arranged on a second side of the brake disc opposite the first side, one or more first and second friction pads supported by the support bracket and / or by the caliper body respectively on the first and second sides of the brake disc, and one or more actuating pistons supported by the caliper body on the first side only of the brake disc and actuatable to bias the first friction pads in the direction of the second side against the brake disc.

[0003] More specifically, the invention concerns a sliding guide for said slidable mounting of the caliper body to the support bracket.

[0004] State of the art

[0005] In the known art, the slidable mounting of the caliper body to the support bracket occurs by means of a plurality of guide pins fixed to the support bracket and extending in a direction perpendicular to the plane of the brake disc. The guide pins are slidably received in corresponding guide holes formed in the caliper body. Alternative solutions are also known in which the guide holes are instead formed in the support bracket.

[0006] In this way, the unilateral thrust of the first friction pads against the brake disc generates a reaction force that makes the caliper body slide, with respect to the support bracket, in the direction opposite to the direction of unilateral thrust, i.e. towards the first side of the brake disc, so that the second wall of the caliper body pushes the second pads against the brake disc, thus obtaining alignment of the opposed pads with respect to the brake disc and bilateral clamping of the brake disc.

[0007] Floating caliper disc brakes of the known art have the disadvantage of an undesired residual braking torque, which occurs after release of the brake lever or pedal, due to insufficient return of the caliper body from its actuated position to its rest position. In fact, while the actuating piston retracts unilaterally, for example due to a roll-back function thereof, allowing the first friction pads to detach from the brake disc, for example due to appropriate pad springs, the slidable caliper body tends to remain excessively displaced towards the first side of the brake disc and the second friction pads therefore remain too close to and in contact with the brake disc.

[0008] There is a need to further reduce the residual braking torque, as well as to improve and make more uniform and repeatable the sliding behaviour of the caliper bodywith respect to the support bracket.

[0009] There is also a need to increase, once the brake is released, the air gap between the second pads and the brake disc on the second side of the brake disc, i.e. on the side opposite the first side on which the actuating piston acts.

[0010] Solution

[0011] The purpose of the present invention is therefore to provide a sliding guide for a floating caliper disc brake, as well as a floating caliper disc brake, having characteristics which allowing to overcome at least in part the drawbacks cited with reference to the known art.

[0012] A further purpose of the invention is to provide a sliding guide for a floating caliper disc brake, as well as a floating caliper disc brake, having characteristics which allow to improve and make more uniform and repeatable the sliding behaviour of the caliper body with respect to the support bracket.

[0013] A further purpose of the invention is to provide a sliding guide for a floating caliper disc brake, as well as a floating caliper disc brake, having characteristics which allow to increase, with the brake released, the air gap between the second pads and the brake disc on the second side of the brake disc, i.e. on the side opposite the first side on which the actuating piston acts.

[0014] These and other purposes are achieved by means of a sliding guide for a floating caliper disc brake, and a floating caliper disc brake, according to the independent claims.

[0015] The dependent claims refer to preferred and advantageous embodiments of the present invention.

[0016] Figures

[0017] To better understand the invention and appreciate its advantages, a description of exemplary and non-limiting embodiments is provided below, with reference to the figures, in which:

[0018] Figure 1 is a side view of a disc brake with floating caliper according to an embodiment of the invention;

[0019] Figure 2 is a sectional view of the disc brake with floating caliper shown in figure 1 ;

[0020] Figure 3 is a perspective view of a disc brake with floating caliper, according to an embodiment, in which a part of a sliding guide is shown in an exploded view,

[0021] Figure 4 is an exploded perspective view of a part of a sliding guide of the disc brake with floating caliper shown in figure 3,

[0022] Figure 5A is a partial sectional view of a disc brake with floating caliper, in the rest configuration,

[0023] Figure 5B is a sectional view of a sliding guide of the disc brake of figure 5A, in the rest configuration,

[0024] Figure 6A is a partial sectional view of the disc brake of figure 5A, in the configuration of approaching the brake disc following an idle stroke,

[0025] Figure 6B is a sectional view of the sliding guide of figure 5B, in the configuration of approaching the brake disc following an idle stroke,

[0026] Figure 7A is a partial sectional view of the disc brake of figure 5A, in the configuration of applying the braking force by the pads on the brake disc, in which the caliper body is shown with a dashed line in the absence of elastic deformation, and with a solid line in the elastically deformed condition,

[0027] Figure 7B is a sectional view of the sliding guide of figure 5B, in the configuration of applying the braking force by the pads on the brake disc, in which the sliding guide is shown with a dashed line in the absence of elastic deformation, and with a solid line in the elastically deformed condition,

[0028] Figure 7C is an enlarged view of the sliding guide shown in figure 7B,

[0029] Figure 8A is a partial sectional view of the disc brake of figure 5A, in the configuration of applying the braking force by the pads on the brake disc, under brake disc pad wear conditions,

[0030] Figure 8B is a sectional view of the sliding guide of figure 5B, in the configuration of applying the braking force by the pads on the brake disc, under brake disc pad wear conditions,

[0031] Figure 9A is a partial sectional view of the disc brake of figure 5A, in the configuration of release of the braking force by the pads on the brake disc, in which the caliper body is shown with a dashed line in the elastically deformed condition, and with a solid line in the absence of elastic deformation following elastic return.

[0032] Figure 9B is a sectional view of the sliding guide of figure 5B, in the configuration of stopping the braking force applied by the pads on the brake disc, in which the sliding guide in the elastically deformed condition is shown with a dashed line, and the sliding guide in the absence of elastic deformation following elastic return is shown with a solid line,

[0033] Figure 9C is a detailed view of the sliding guide shown in figure 9B,

[0034] Figure 10A is a partial sectional view of the disc brake of figure 5A, in theconfiguration of stopping the braking force applied by the pads on the brake disc, under conditions of completed elastic return of a return spring of the sliding guide,

[0035] Figure 10B is a sectional view of the sliding guide of figure 5B, in the configuration of stopping the braking force applied by the pads on the brake disc, under conditions of completed elastic return of a return spring of the sliding guide,

[0036] Figure 1 1 is a sectional view of a sliding guide according to one embodiment of the invention,

[0037] Figure 12 is an exploded perspective view of a disc brake with floating caliper according to one embodiment of the invention,

[0038] Figure 13 is an exploded perspective view of a part of a sliding guide in a disc brake with floating caliper according to one embodiment of the invention,

[0039] Figure 14 is a sectional view of a sliding guide in a disc brake with floating caliper according to one embodiment of the invention,

[0040] Figures 15A-15E schematically show the steps of a braking operation of a disc brake with floating caliper according to one embodiment of the invention,

[0041] Figures 16A-16E schematically show the steps of a braking operation of a disc brake with floating caliper according to a further embodiment of the invention.

[0042] Description of some preferred exemplary embodiments

[0043] Disc brake

[0044] With reference to the figures, a disc brake 1 of the floating caliper type comprises a support bracket 2 connectable, for example by screws or bolts 4, to the vehicle suspension, a caliper body 5 slidably connected to the support bracket 2 and forming a first wall 6 (inner wall) arranged on a first side 7 (vehicle inner side) of a brake disc 8 and a second wall 9 (outer wall) arranged on a second side 10 (vehicle outer side) of the brake disc 8 opposite the first side 7, one or more first friction pads 11 and second friction pads 12 supported by the support bracket 2 and / or by the caliper body 5 respectively on the first side 7 and the second side 10 of the brake disc 8, and one or more actuating pistons 13 supported unilaterally in the first wall 6 of the caliper body 5 on the first side 7 of the brake disc 8 and actuatable to bias the one or more first friction pads 11 in the direction of the second side 10 against the brake disc 8.

[0045] Sliding guide

[0046] The slidable connection of the caliper body 5 to the support bracket 2 occurs by means of one or more sliding guides 15 which impose a relative sliding direction between the caliper body 5 and the support bracket 2 (guide axis 18) parallel to a thrust directionof the actuating piston 13 and orthogonal to a disc plane 14 of the brake disc 8.

[0047] The sliding guide 15 comprises: a) a guide pin 16 forming a cylindrical guide portion 17 defining a guide axis 18 and a fixing portion 19 for fixing the guide pin 16 to the support bracket 2 of the disc brake 1 (fig. 1-11 , 15A-E), or for fixing the guide pin 16 to a caliper body 5 of the disc brake (fig. 12-14, 16A-E), b) a floating body 20 forming a tubular cylindrical sliding portion 21 and a first spring seat 22, c) a return spring 23, d) one or more friction elements 24, for example elastomeric, e) a guide seat 25 formed in or connectable to the caliper body 5 of the disc brake 1 (fig. 1-11 , 15A-E), or formed in or connectable to the support bracket 2 (fig. 12-14, 16A-E), and forming a preferably cylindrical guide hole 26, f) a second spring seat 27, wherein, in the configuration in which the guide seat 25 is formed in or connected to the caliper body 5 (fig. 1-11 , 15A-E), the guide pin 16 is fixable to the support bracket 2 and the second spring seat 27 is formed by the guide seat 25, or wherein, in the configuration in which the guide seat 25 is formed in or connected to the support bracket 2 (fig. 12-14, 16A-E), the guide pin 16 is fixable to the caliper body 5 and the second spring seat 27 is formed in or connected to the support bracket 2, wherein:- the tubular sliding portion 21 is slidably fitted onto the guide portion 17,- the friction element 24 is trapped in a first sliding interface 28 between the guide portion17 and the sliding portion 21 ,- the sliding portion 21 is slidably inserted into the guide hole 26,- the first spring seat 22 and second spring seat 27 face each other in the direction of the guide axis 18 and the return spring 23 is connected between the first spring seat 22 and the second spring seat 27 in an elastically deformable manner in the direction of the guide axis 18.

[0048] According to one embodiment (fig. 1-1 1 , 15A-E), the fixing portion 19 of the guide pin 16 is fixable to the support bracket 2. In addition, the guide seat 25 is formed in or is connectable to the caliper body 5 and forms the cylindrical guide hole 26 and the second spring seat 27.

[0049] During relative sliding of the guide seat 25 with respect to the guide pin 16, in a first relative sliding range (corresponding to a braking stroke without brake disc padwear), the guide seat 25 slides with respect to the floating body 20 against the elastic force of the return spring 23, elastically deforming the return spring 23 so as to elastically compress the return spring 23, while the friction element 24 prevents sliding of the sliding portion 21 with respect to the guide portion 17.

[0050] Upon exceeding the first relative sliding range (corresponding to a braking stroke with extra stroke due to pad wear), the friction element 24 slides together with the sliding portion 21 with respect to the guide portion 17 along the guide axis 18.

[0051] With the sliding guide 15 configured in this manner, during braking, the travel of the caliper body 5 with respect to the support bracket 2 to clamp the brake disc 8 generates relative sliding between the guide seat 25 and the floating body 20 and sliding between the floating body 20, together with the friction elements 24, and the guide portion 17. In particular, such sliding occurs because the constraining reaction of the compressed return spring 23 exceeds the friction force between the friction element 24 and the guide portion 17.

[0052] At the end of the braking operation, the return spring 23, which acts between the guide seat 25 and the floating body 20, repositions the caliper body 5 in its planned rest position, ensuring a desired gap between the brake disc 8 and the (second) friction pad 12 and thus overcoming the problem of residual braking torque.

[0053] With progressive wear of the pads 11 , 12 (which occurs during braking), the travel of movement of the caliper body 5 with respect to the support bracket 2, necessary to clamp the brake disc 8, increases by a value corresponding to the sum of the worn thickness of the pads 1 1 , 12. This extra travel due to wear of the pads 11 , 12, once the compressed return spring 23 reaches its deformation limit and rigidly generates a reaction greater than the friction force 24 between the friction element 24 and the guide portion 17, does not cause any further relative sliding between the guide seat 25 and the floating body 20, but instead causes sliding of the friction element 24 and thus a displacement or repositioning of the floating body 20 with respect to the guide pin 16 which determines a new planned rest position of the caliper body 5.

[0054] In fact, at the end of braking, the return spring 23, which acts between the guide seat 25 and the floating body 20, does not alter the (new) relative position reached between the floating body 20 and the guide pin 16, but repositions the caliper body 5 in the new planned rest position, thus ensuring a desired gap between the brake disc 8 and the pads regardless of the thickness of pad wear.

[0055] According to an alternative embodiment (fig. 12-14, 16A-E), the fixing portion 19 of the guide pin 16 is fixable to the caliper body 5. In addition, the guide seat 25 is formedin or is connectable to the support bracket 2 and forms the cylindrical guide hole 26. Furthermore, the second spring seat 27 is formed by the support bracket 2 or by an additional component connectable to the support bracket 2. For example, the second spring seat 27 may be formed by a threaded ring nut 52 screwed to the support bracket 2.

[0056] According to this embodiment, during braking a relative sliding occurs of the guide pin 16, and therefore of the caliper body 5, with respect to the guide seat 25, and therefore to the support bracket 2, along the guide axis 18.

[0057] During relative sliding of the guide pin 16 with respect to the guide seat 25, in a first relative sliding range (corresponding to a braking stroke without pad wear), the one or more friction elements 24 pull the floating body 20 so as to elastically compress the return spring 23, and at the same time the one or more friction elements 24 prevent the sliding portion 21 from slipping with respect to the guide portion 17.

[0058] Upon exceeding the first relative sliding range (corresponding to a braking stroke with extra travel due to pad wear), the friction element 24 slides together with the sliding portion 21 with respect to the guide portion 17 along the guide axis 18. In particular, such sliding occurs because the constraining reaction of the compressed return spring 23 exceeds the friction force between the friction element 24 and the guide portion 17.

[0059] At the end of the braking action, the return spring 23 decompresses and moves the caliper body 5 away from the brake disc 8, and thus moves the friction pads 12 on the reaction side away from the brake disc 8. In addition, the one or more friction elements 24 lock the floating body 20 relative to the guide portion 17 in the new equilibrium position, and the action of the return spring 23 repositions the caliper body 5 in its original rest position.

[0060] With the sliding guide 15 configured in this manner, during braking, the travel of movement of the caliper body 5 with respect to the support bracket 2 to clamp the brake disc 8 generates relative sliding between the floating body 20 and the guide seat 25, and sliding between the floating body 20, together with the friction elements 24, and the guide portion 17.

[0061] At the end of braking, the return spring 23, which acts between the support bracket 2, or between the threaded ring nut 52, and the floating body 20, repositions the caliper body 5 in its new rest position, ensuring a desired gap between the brake disc 8 and the (second) friction pad 12 and thus overcoming the problem of residual braking torque.

[0062] With progressive wear of the pads 1 1 , 12, the travel of movement of the caliperbody 5 with respect to the support bracket 2, necessary to clamp the brake disc 8, increases by a value corresponding to the sum of the worn thickness of the pads 1 1 , 12. This extra travel due to wear of the pads 1 1 , 12, once the compressed return spring 23 reaches its deformation limit and rigidly generates a reaction greater than the friction force 24 between the friction element 24 and the guide portion 17, does not cause any further relative sliding between the guide seat 25 and the floating body 20, but instead causes sliding of the friction element 24 and thus a displacement or repositioning of the floating body 20 with respect to the guide pin 16 which determines a new planned rest position of the caliper body 5.

[0063] In fact, at the end of braking, the return spring which acts between the guide seat 25 and the floating body 20 does not alter the (new) relative position reached between the floating body 20 and the guide pin 16 but repositions the caliper body 5 in the new planned rest position, thus ensuring a desired gap between the brake disc 8 and the pads regardless of the thickness of pad wear.

[0064] Guide pin

[0065] The guide pin 16 extends between its front end 42 on a front side 40 of the sliding guide 15 and its rear end 43 on a rear side 41 of the sliding guide 15.

[0066] According to one embodiment, the guide pin 16 is made of metal, e.g. steel. The guide portion 17 forms a first cylindrical guide surface 31 , concentric with the guide axis 18 and facing radially outwards.

[0067] The fixing portion 19 may comprise a threaded rod 32 formed at the front end 42 of the guide pin 16 and intended to be screwed into a corresponding threaded hole 33 of the support bracket 2 (fig. 1-11 , 15A-E) or of the caliper body 5 (fig. 12-14, 16A-E).

[0068] The guide pin 16 comprises a body 30 which forms the guide portion 17 with the first cylindrical guide surface 31 . According to one embodiment, the body 30 is internally hollow or tubular. Advantageously, this reduces the weight of the guide pin 16.

[0069] The entire guide pin 16 or the guide portion 17 and the fixing portion 19 may be formed in a single piece.

[0070] Alternatively, the fixing portion 19 is formed by a fixing screw inserted into or extending through the hollow body 30 and forming the threaded rod 32.

[0071] Floating body

[0072] The floating body 20 extends between its front end 44 on the front side 40 of the sliding guide 15 and its rear end 45 on the rear side 41 of the sliding guide 15.

[0073] According to one embodiment, the floating body 20 is made of metal, for examplesteel or brass.

[0074] The sliding portion 21 forms a first cylindrical sliding surface 35, concentric with the guide axis 18 and facing radially inwards. The first sliding surface 35 and the first guide surface 31 form the first sliding interface 28.

[0075] The sliding portion 21 also forms a second cylindrical sliding surface 57, concentric with the guide axis 18 and facing radially outwards. The second sliding surface 57 and a second guide surface 56 of the guide seat 25 form a second sliding interface 58.

[0076] The first spring seat 22 may be formed by an annular flange 34 protruding from the sliding portion 21 radially outwards. The annular flange 34 may be substantially planar and lie in a plane orthogonal to the guide axis 18.

[0077] Preferably, the annular flange 34 or the first spring seat 22 is formed at the rear end 45 of the sliding portion 21 or of the floating body 20.

[0078] With further advantage, the first spring seat 22 and the sliding portion 21 are formed in one single piece.

[0079] Advantageously, the annular flange 34, or more generally the first spring seat 22, forms a first spring backing surface 36 transverse to the guide axis 18 and facing the front side 40 of the sliding guide (respectively towards the front end 44 of the floating body 20), and the return spring 23 rests with its rear side in a rearward direction against the first spring backing surface 36.

[0080] The above-mentioned features of the floating body 20 facilitate and reduce the cost of manufacturing, prevent space interference between the individual components, and allow a compact construction of the sliding guide 15.

[0081] According to one embodiment, the floating body 20, preferably the first sliding surface 35, forms one or more, preferably two, cavities 37 that accommodate and retain (in a captive manner) said one or more, preferably two, friction elements 24 (pressing against the first guide surface 31 ), advantageously a first friction element 24 positioned in a front end portion of the floating body 20 and a second friction element 24 positioned in a rear end portion of the floating body 20.

[0082] Advantageously, the cavities 37 are annular grooves and the friction elements 24 are O-rings housed in the annular grooves (fig. 1-10).

[0083] Alternatively, the friction elements 24 are rubber rings with rectangular crosssection (fig. 13-14), positioned inside the cavities 37.

[0084] According to an alternative embodiment (fig. 12-14), the first spring seat 22 maybe formed by a recess formed in the sliding portion 21 .

[0085] Return spring 23

[0086] The return spring 23 extends between its front end 50 facing the front side 40 of the sliding guide 15 and its rear end 51 facing the rear side 41 of the sliding guide 15.

[0087] According to one embodiment, the return spring 23 is made of metal, for example spring steel. According to an alternative embodiment, the return spring 23 is replaced by an elastomeric element.

[0088] Advantageously, the return spring 23 has an annular shape or is a cylindrical helical compression spring and is mounted externally on the tubular sliding portion 21 of the floating body 20.

[0089] According to one embodiment, the sliding guide 15 may comprise a threaded cover 53 fitted onto the guide portion 17. The threaded cover is screwed to the caliper body 5 so as to preload the return spring 23.

[0090] In one embodiment, the return spring 23 has an annular shape or is a corrugated spring, or a conical spring washer.

[0091] Alternatively, the return spring 23 is a cylindrical helical compression spring.

[0092] According to one embodiment, the support bracket 2 may comprise a threaded ring nut 52 fitted onto the guide portion 17. The threaded ring nut 52 is screwed to the support bracket 2 so as to preload the return spring 23, in particular the cylindrical helical compression spring.

[0093] The elastic reaction force of the return spring 23, e.g. in compression, in a first relative sliding range is lower than a friction threshold force beyond which the friction elements 24 begin to slip. Upon exceeding the first relative sliding range, when the deformation limit of the return spring 23 is reached, the constraining reaction force of the return spring 23 exceeds the friction threshold beyond which the friction elements 24 begin to slip. In this way, the axial dimension of the return spring 23 determines the length of the braking stroke and the elastic return stroke of the caliper body 5 with respect to the support bracket 2, while the extra-stroke due to wear of the pads 11 , 12 and to deformation of the caliper body 5 begins when the return spring 23 reaches its deformation limit, e.g. in compression, such that the first spring seat 22 and second spring seal 27 are rigidly engaged with one another.

[0094] Guide seat 25

[0095] The guide seat 25 extends between its front end 54 on the front side 40 of the sliding guide 15 and its rear end 55 on the rear side 41 of the sliding guide 15.

[0096] According to one embodiment, the guide seat 25 is formed directly in the caliper body 5 (fig. 1-11 , 15A-E).

[0097] According to one embodiment, the guide seat 25 is made of metal, for example aluminium or cast iron.

[0098] The guide hole 26 forms a second cylindrical guide surface 56, concentric with the guide axis 18 and facing radially inwards.

[0099] The second spring seat 27 may be formed by an annular shoulder 59 extending from the guide hole 26 radially outwards. The annular shoulder 59 may be substantially planar and lie in a plane orthogonal to the guide axis 18.

[0100] Preferably, the annular shoulder 59 or the second spring seat 27 is formed at the rear end 55 of the guide seat 25.

[0101] With further advantage, the second spring seat 27 and the guide hole 26 are formed in one single piece.

[0102] Advantageously, the annular shoulder 59, or more generally the second spring seat 27, forms a second spring backing surface 60 transverse to the guide axis 18 and facing the rear side 41 of the sliding guide (respectively towards the rear end 55 of the guide seat 25), and the return spring 23 rests with its front side in a forward direction against the second spring backing surface 60.

[0103] According to one embodiment, the guide seat 25 is formed directly in the support bracket 2 (fig. 12-14, 16A-E).

[0104] Return means 46

[0105] According to one embodiment, the sliding guide 15 comprises return means 46 which interact with the guide seat 25 and with the floating body 20 to return the floating body 20.

[0106] According to one embodiment, the return means 46 comprise a cover 53 (fig. 1-10).

[0107] The cover 53 is connected to the caliper body 5. Preferably, the cover 53 is fixed to the caliper body 5, for example screwed to the caliper body 5 or press-fitted into the caliper body 5.

[0108] The cover 53 is fitted onto the guide portion 17 and is positioned so as to axially preload the return spring 23 in compression.

[0109] Advantageously, such axial preload of the return spring 23 ensures the absence of play between the return spring 23 and the floating body 20 under all conditions, both in the rest condition and during braking.

[0110] According to one embodiment, the cover 53 forms a cylindrical housing wall 78 and an abutment wall 79.

[0111] The housing wall 78 is fitted onto the guide portion 17.

[0112] The abutment wall 79 is positioned in abutment against the floating body 20. Specifically, the abutment wall 79 abuts an annular flange 34 of the floating body 20, and is positioned opposite the return spring 23 with respect to the annular flange 34 of the floating body 20.

[0113] According to one embodiment, the return means 46 may comprise at least two stroke-limiting cavities 47, 48 formed in the guide seat 25 and in the floating body 20, and a stroke-limiting tooth 49 which engages the stroke-limiting cavity 47, 48 with a limited axial clearance (fig. 1 1 ).

[0114] Advantageously, the return means 46 may comprise a first stroke-limiting cavity 47, for example a first annular groove, formed in the guide seat 25, a second stroke-limiting cavity 48, for example a second annular groove, formed in the floating body 20, and a stroke-limiting tooth 49, for example a ring which engages the first strokelimiting cavity 47 and the second stroke-limiting cavity 48 with a limited axial clearance.

[0115] Advantageously, the stroke-limiting tooth 49 comprises a metal ring comolded with an elastomeric dust cap which will be described later.

[0116] Front and rear dust caps

[0117] The sliding guide comprises a front dust cap 61 , preferably elastomeric and possibly bellows-shaped, which surrounds the front end 44 of the floating body 20 and the front terminal regions of the first 28 and second 58 sliding interfaces.

[0118] In one embodiment, the front dust cap 61 extends between its front end 62, facing the front side 40 of the sliding guide 15, for example a front annular collar 64 housed in an annular groove 66 of the guide pin 16, and its rear end 63 facing the rear side 41 of the sliding guide 15, for example a rear annular collar 65 housed in an annular groove 67, 47 of the guide seat 25.

[0119] Advantageously, the rear annular collar 65 forms said stroke-limiting tooth 49 and may comprise a metal ring co-molded with the elastomeric material of the front dust cap 61.

[0120] The sliding guide 15 further comprises a rear dust cap 68, preferably elastomeric and possibly cup-shaped and / or with a bellows-shaped side wall, which surrounds the rear end 45 of the floating body 20 and the rear terminal regions of the first 28 and second 58 sliding interfaces, and optionally the rear end 43 of the guide pin16.

[0121] According to one embodiment, the rear dust cap 68 is hooked to the cover 53. The cover 53 is screwed integrally to the caliper body 5. In this way it is ensured that the rear dust cap 68, preferably bellows-shaped, is always hooked to the cover 53, and the ingress of dust or other contaminants is prevented. Preferably, a coupling seat for the rear dust cap 68 on the cover 53 is formed inside the cover 53.

[0122] In one embodiment, the rear dust cap 68 extends between its front end 69, facing the front side 40 of the sliding guide 15, for example a front annular collar 71 housed in an annular recess 72 of the guide seat 25, and its rear end 70 facing the rear side 41 of the sliding guide 15, for example a closed bottom of the rear dust cap 68 in cup form, or a rear annular collar (not shown) housed in a corresponding recess of the guide pin 16.

[0123] According to a further embodiment, the sliding guide 15 comprises a rear dust cap 68, preferably elastomeric and possibly cup-shaped and / or with a bellows- shaped side wall, fitted onto the sliding guide 15, interposed between the support bracket 2 and the caliper body 5. According to one embodiment, the rear dust cap 68 is hooked to the support bracket 2 and is hooked to the sliding guide 16 or alternatively to the caliper body 5.

[0124] Support bracket 2

[0125] The support bracket 2 comprises, for example, two fixing holes 73 suitable for receiving corresponding fixing screws 4 to connect the support bracket 2 to a steering knuckle of the vehicle suspension, while the brake disc 8 is fixed, in a known manner, to a wheel of the vehicle itself.

[0126] Similarly to the caliper body 5, the support bracket 2 may also form a first portion 38 arranged on the first side 7 of the brake disc 8 and a second portion 39 arranged on the second side 10 of the brake disc, and which may serve to support the corresponding first friction pads 11 and second friction pads 12.

[0127] According to one embodiment, the support bracket 2 comprises a threaded hole 33 for screwing the sliding guide 15 (fig. 1-1 1 , 15A-E).

[0128] According to an alternative embodiment, a threaded hole 33 for screwing the sliding guide 15 is formed in the caliper body 5, and the support bracket 2 comprises a guide seat 25 (fig. 12-14, 16A-E).

[0129] Caliper body 5

[0130] The caliper body 5 comprises the first wall 6 intended to face, when the brake is mounted, the inside of the vehicle, and the opposite second wall 9 intended toface the outside of the vehicle. The first 6 and second 9 walls are spaced from each other so as to allow positioning of the support bracket 2 between them, and are rigidly connected to each other, preferably by two lateral bridge elements 74 arranged at the opposite ends of the first 6 and second 9 walls, and a central bridge element 75 arranged between the lateral bridge elements 74, preferably halfway between them. The lateral 74 and central 75 bridge elements extend over the support bracket 2.

[0131] The first 6 and second 9 walls, together with the lateral bridge elements 74 and central bridge element 75, delimit two large openings 76 arranged substantially in correspondence with the pads 1 1 , 12.

[0132] The first wall 6 of the caliper body 5 is provided with one or more piston seats 77 for the one or more hydraulic or electromechanical actuating pistons 13, to urge the one or more first friction pads 11 arranged in correspondence with the first wall 6 of the caliper body 5 against the brake disc 8.

[0133] The second wall 9 of the caliper body 5 forms reaction surfaces with one or more second pads 12 arranged in correspondence with the second wall 9 of the caliper body 5.

[0134] The caliper body 5 may form two lateral guide seats 25 of two respective lateral sliding guides 15, at two opposite end regions, for example at the two lateral bridge elements 74.

[0135] The caliper body 5 may additionally form a further central guide seat 25 of a further central sliding guide 15, for example at the central bridge element 75.

[0136] According to an alternative embodiment (fig. 12-14, 16A-E), the support bracket 2 may form two lateral guide seats 25 of two respective lateral sliding guides 15. The support bracket 2 may additionally form a further central guide seat 25 of a further central sliding guide 15.

[0137] In a known manner, the friction pads may be housed in pad seats of the support bracket 2 and slidable in a direction transverse to the disc plane 14, but restrained in the tangential or circumferential direction of the brake disc 8 by a stop surface, and in the radial direction of the brake disc 8 by contrast surfaces, which may be formed by the support bracket 2 and / or the caliper body 5.

[0138] According to one embodiment, both the support bracket 2 and the caliper body 5 are made, preferably as a single piece, of aluminium alloy. Alternatively, they are made of cast iron or metal in general. Preferably, the support bracket 2 is made of cast iron and the caliper body 5 is made of aluminium alloy.

[0139] The sliding guide 15 and the disc brake 1 according to the invention offernumerous advantages.

[0140] They contribute to a reduction of the residual braking torque, as well as to improving and making more uniform and repeatable the sliding behaviour of the caliper body relative to the support bracket.

[0141] They allow increasing and ensuring, with the brake released, the clearance between the second pads and the brake disc on the second side of the brake disc, that is on the side opposite to the first side on which the actuating piston acts.

[0142] With reference to figures 5A-5B, when the vehicle is moving forward and no braking action is performed, i.e. in the rest condition of the sliding guide 15 and of the disc brake 1 , the friction pads 1 1 , 12, having thickness “s”, are at a distance “x” and “y” from the brake disc 8. The floating body 20 is stationary and is in contact with the cover 53, fixed to the caliper body 5, which axially presses the floating body 20 and allows it to apply a preload on the return spring 23, which extends for a length “a”. The floating body 20 is located at a distance “b” from the support bracket 2.

[0143] With reference to figs. 6A-6B, when the vehicle begins braking, the friction pads 11 , 12 come into contact with the brake disc 8. The floating body 20 remains stationary, while the caliper body 5 slides on the floating body 20 by a length “x”, equal to the initial clearance between the friction pad 12 and the brake disc 8 on the second side 10 (reaction side) before the braking action. The return spring 23 is compressed and reduces its axial length to a value “a1 ” (a1 = a - x). The floating body 20 remains at a distance “b” from the support bracket 2.

[0144] With reference to figs. 7A-7C, as braking continues, after the recovery of clearances a significant force is exerted which leads the disc brake 1 , and in particular the caliper body 5, to elastically deform. In particular, the caliper body 5 elastically deforms in the direction of the guide axis 18 by a length “Zel”. This deformation is such as to compress the return spring 23 (for simplicity, in fig. 7B the return spring 23 is shown fully deformed, i.e. compressed by an amount “a1 ”), which exerts on the floating body 20 a force greater than the friction force exerted by the friction elements 24, for example elastomeric friction elements. Consequently, the floating body 20 begins to slide on the guide portion 17 by a length Zel - a1 . Therefore, the floating body 20 is positioned at a distance “b1 ” from the support bracket 2 (b1 = b + (Zel - a1 )).

[0145] With reference to figures 8A-8B, during braking, even if only slightly, the friction pads 1 1 , 12 wear by an amount “k”. Consequently, the axial thickness of the friction pads 11 , 12 will be “s - k”. As a result of this wear, the floating body 20 translates by the same length “k” along the guide portion 17, moving to a distance “b2” from thesupport bracket 2 (b2 = b1 + k). The return spring 23 remains fully compressed and the floating body 20 remains at a distance “a” from the cover 53.

[0146] With reference to figs. 9A-9C, at the end of braking the braking force ceases and the disc brake 1 , in particular the caliper body 5, begins to recover the elastic deformations. The caliper body 5 slides on the floating body 20 in the direction of the brake disc 8 by an amount “Zel”, and the floating body 20 remains stationary and at a distance “b2" from the support bracket 2. At the same time, the return spring 23 decompresses and increases its axial length by an amount “a2” (a2 = Zel). A distance “x1 ” remains between the floating body 20 and the cover 53 (x1 = a - Zel). If the elastic deformation were large (e.g. Zel > a), during the return step the cover 53 would come into contact with the floating body 20, drawing the floating body 20 towards the brake disc 8.

[0147] With reference to figs. 10A-10B, simultaneously or subsequently to the elastic return of the caliper body 5 (depending on the structure and dynamics of the disc brake 1 ), the elastic return of the return spring 23 takes place, which tends to axially expand and return to its initial condition with length “a”. Since the friction force of the friction elements 24 is greater than the elastic deformation force of the return spring 23, the floating body 20 remains stationary and the return spring 23 pushes the caliper body 5 towards the brake disc 8 by an amount equal to “x1 ”. The sliding stops when the cover 53, integral with the caliper body 5, abuts the floating body 20. The final result is that the friction pad 12 on the reaction side moves away from the brake disc 8 by an amount “x1 ”, eliminating the phenomenon of residual torque.

[0148] Obviously, to the sliding guide 15 and the disc brake 1 according to the invention, a person skilled in the art, in order to meet contingent and specific needs, may introduce further modifications and variants, all of which are nevertheless included within the scope of protection of the invention, as defined by the following claims.List of References1 . Disc brake2. Support bracket4. Suspension screws, bolts5. Caliper body6. First wall7. First side8. Brake disc9. Second wall10. Second side11 . First friction pads12. Second friction pads13. Actuating piston14. Disc plane15. Sliding guide16. Guide pin17. Guide portion18. Guide axis19. Fixing portion20. Floating body21. Sliding portion22. First spring seat23. Return spring24. Friction elements25. Guide seat26. Guide hole27. Second spring seat28. First sliding interface30. Internally hollow body31 . Guide surface32. Threaded rod33. Threaded hole of the bracket34. Annular flange35. Sliding surface36. First spring backing surface

Claims

Claims1. A sliding guide (15) for a disc brake (1 ) of the floating caliper type, for a sliding connection between a caliper body (5) and a support bracket (2) of the disc brake (1), said sliding guide (15) comprising: a) a guide pin (16) forming a cylindrical guide portion (17) defining a guide axis (18) and a fixing portion (19) for fixing the guide pin (16) to a support bracket (2) of the disc brake (1) or to a caliper body (5) of the disc brake (1), b) a floating body (20) forming a tubular cylindrical sliding portion (21 ) and a first spring seat (22), c) a return spring (23), d) one or more friction elements (24) e) a guide seat (25) formed in or connectable to the caliper body (5) or to the support bracket (2), and forming a preferably cylindrical guide hole (26), f) a second spring seat (27) formed by the guide seat (25) formed in or connectable to the caliper body (5), or formed in or connectable to the support bracket (2), wherein:- the tubular sliding portion (21) is slidingly fitted onto the guide portion (17),- the friction element (24) is interposed between the guide portion (17) and the sliding portion (21),- the sliding portion (21) is slidingly inserted into the guide hole (26),- the first (22) and second (27) spring seats face each other in the direction of the guide axis (18) and the return spring (23) is connected between the first spring seat (22) and the second spring seat (27) in an elastically deformable manner in the direction of the guide axis (18).

2. Sliding guide (15) according to claim 1 , wherein:- the fixing portion (19) of the guide pin (16) is fixable to the support bracket (2) of the disc brake (1); and- the guide seat (25) is formed in or connectable to the caliper body (5) of the disc brake (1), and forms the cylindrical guide hole (26) and the second spring seat (27).

3. Sliding guide (15) according to claim 2, wherein:- during a relative sliding of the guide seat (25) with respect to the guide pin (16), in a first relative sliding range, the guide seat (25) slips with respect to the floating body (20) so as to compress the return spring (23) elastically, while the friction element (24)prevents the sliding portion (21) from slipping with respect to the guide portion (17),- upon exceeding the first relative sliding range, the friction element (24) slips together with the sliding portion (21) with respect to the guide portion (17) along the guide axis (18).

4. Sliding guide (15) according to claim 1 , wherein:- the fixing portion (19) of the guide pin (16) is fixable to the caliper body (5) of the disc brake (1); and- the guide seat (25) is formed in or connectable to the support bracket (2) of the disc brake (1), and forms the cylindrical guide hole (26), and wherein the second spring seat (27) is formed in or connectable to the support bracket (2).

5. Sliding guide (15) according to claim 4, wherein:- during a relative sliding of the guide pin (16), integral with the caliper body (5), with respect to the guide seat (25) along the guide axis (18), in a first relative sliding range the one or more friction elements (24) pull the floating body (20) so as to compress the return spring (23) elastically, and at the same time the one or more friction elements (24) prevent the sliding portion (21) from slipping with respect to the guide portion (17),- upon exceeding the first relative sliding range, the friction element (24) slips together with the sliding portion (21) with respect to the guide portion (17) along the guide axis (18).

6. Sliding guide (15) according to one of the preceding claims, wherein:- the guide pin (16) extends between a front end (42) thereof on a front side (40) of the sliding guide (15) and a rear end (43) thereof on a rear side (41) of the sliding guide (15),- the guide portion (17) forms a first cylindrical guide surface (31 ), concentric with the guide axis (18) and facing radially outwards,- the fixing portion (19) comprises a threaded rod (32) formed at the front end (42) of the guide pin (16) and intended to be screwed into a corresponding threaded hole (33) of the support bracket (2) or of the caliper body (5),- the guide pin (16) comprises a body (30) which forms the guide portion (17).- wherein the guide portion (17) and the fixing portion (19) are formed in one piece.

7. Sliding guide (15) according to any one of claims 1 to 5, wherein the fixing portion (19) is formed by a fixing screw inserted into the hollow body (30) and forming the threaded rod (32).

8. Sliding guide (15) according to any one of claims from 1 to 3, wherein:- the floating body (20) extends between a front end (44) thereof on a front side (40) of the sliding guide (15) and a rear end (45) thereof on a rear side (41) of the sliding guide (15),- the sliding portion (21) forms a first cylindrical sliding surface (35), concentric with the guide axis (18) and facing radially inwards,- the sliding portion (21) forms a second cylindrical sliding surface (57), concentric with the guide axis (18) and facing radially outwards,- the first spring seat (22) is formed by an annular flange (34) protruding radially outwards from the sliding portion (21).

9. Sliding guide (15) according to any one of claims 1 to 3, wherein the first spring seat(22) is formed at a rear end (45) of the floating body (20).

10. Sliding guide (15) according to any one of the preceding claims, wherein the first spring seat (22) and the sliding portion (21) are formed in one piece.

11. Sliding guide (15) according to any one of the preceding claims, wherein:- the first spring seat (22) forms a first spring backing surface (36) transverse to the guide axis (18) and facing a front side (40) of the sliding guide and the return spring(23) rests with a rear end (51) thereof in a rearward direction against the first spring backing surface (36), and- the second spring seat (27) forms a second spring backing surface (60) transverse to the guide axis (18) and facing a rear side (41 ) of the sliding guide and the return spring (23) rests with a front end (50) thereof in a forward direction against the second spring backing surface (60).

12. Sliding guide (15) according to any one of the preceding claims, wherein the floating body (20) forms at least one cavity (37) which accommodates and retains the at least one friction element (24) in a captive manner.

13. Sliding guide (15) according to claim 8, wherein the first sliding surface (35) forms two annular grooves (37) which accommodate and retain two elastomeric O-rings which form said friction elements (24) and press against the first guide surface (31), wherein a first annular groove (37) is positioned in a front end portion of the floating body (20) and a second annular groove (37) is positioned in a rear end portion of the floating body (20), or wherein the friction elements (24) are rubber rings with rectangular section.

14. Sliding guide (15) according to claim 1 , wherein the first spring seat (22) is formed by a recess formed in the sliding portion (21 ).

15. Sliding guide (15) according to any one of the preceding claims, wherein the return spring (23):- extends between a front end (50) thereof facing a front side (40) of the sliding guide (15) and a rear end (51 ) thereof facing a rear side (41 ) of the sliding guide (15),- is made of spring steel, or wherein the return spring (23) is replaced by an elastomeric element,- is annular in shape or is a cylindrical helical compression spring and is inserted externally on the tubular sliding portion (21) of the floating body (20).

16. Sliding guide (15) according to any one of claims 4 or 5, wherein the return spring (23):- extends between a front end (50) thereof facing a front side (40) of the sliding guide (15) and a rear end (51 ) thereof facing a rear side (41 ) of the sliding guide (15),- is made of spring steel, or wherein the return spring (23) is replaced by an elastomeric element,- is a cylindrical helical compression spring,- is annular in shape or is a corrugated spring, or a conical spring washer, and wherein the support bracket (2) comprises a threaded ring nut (52) fitted onto the guide portion (17) and screwed to the support bracket (2) so as to preload the return spring (23), and wherein the second spring seat (27) is formed by a wall of the threaded ring nut (52) facing the return spring (23).

17. Sliding guide (15) according to any one of the preceding claims, wherein in a firstrelative sliding range the elastic reaction force of the return spring (23) under compression is less than a friction threshold force beyond which the friction elements (24) begin to slip, and wherein upon exceeding the first relative sliding range, once the deformation limit of the return spring (23) has been reached, the constraining reaction force of the return spring (23) exceeds the friction threshold beyond which the friction elements (24) begin to slip.

18. Sliding guide (15) according to any one of the preceding claims, wherein:- the guide seat (25) extends between a front end (54) thereof on a front side (40) of the sliding guide (15) and a rear end (55) thereof on a rear side (41) of the sliding guide (15),- the guide hole (26) forms a second cylindrical guide surface (56), concentric with the guide axis (18) and facing radially inwards,- the second spring seat (27) is formed by an annular shoulder (59) formed at the rear end (55) of the guide seat (25) and extending from the guide hole (26) radially outwards, or is formed by a wall of a threaded ring nut (52) facing the floating body (20) and screwed to the support bracket (2).

19. Sliding guide (15) according to any one of claims from 1 to 3, comprising return means (46) which interact with the guide seat (25) and the floating body (20) to take back the floating body (20).

20. Sliding guide (15) according to claim 19, wherein the return means (46) comprise a cover (53) fixed to the caliper body (5), wherein the cover (53) is fitted onto the guide portion (17) and is positioned so as to preload the return spring (23) axially under compression, and wherein the cover (53) forms a cylindrical housing wall (78) and an abutment wall (79), wherein the housing wall (78) is fitted onto the guide portion (17) and the abutment wall (79) is positioned abutting against the floating body (20).

21. Sliding guide (15) according to claim 19, wherein the return means (46) comprise at least two stroke limiting cavities (47, 48) formed in said guide seat (25) and said floating body (20) and a stroke limiting tooth (49) which engages the at least one stroke limiting cavity (47), (48) with a limited axial clearance.

22. Sliding guide (15) according to claim 19, wherein the return means (46) comprise a first annular groove formed in the guide seat (25), a second annular groove formed in the floating body (20), and a metal ring which engages the first annular groove and the second annular groove with limited axial clearance, wherein said metal ring is co-molded with an elastomeric dust cap.

23. A disc brake (1) of the floating caliper type, comprising:- a support bracket (2) connectable to a vehicle suspension,- a caliper body (5) slidingly connected to the support bracket (2) and forming a first wall (6) arranged on a first side (7) of a brake disc (8) and a second wall (9) arranged on a second side (10) of the brake disc (8) opposite to the first side (7),- one or more first friction pads (11) and second friction pads (12) supported by the support bracket (2) and / or the caliper body (5) on the first side (7) and second side (10) of the brake disc (8), respectively, and / or- one or more actuating pistons (13) supported unilaterally in the first wall (6) of the caliper body (5) on the first side (7) of the brake disc (8) and actuatable to bias the one or more first friction pads (11) in the direction of the second side (10) against the brake disc (8), characterized in that the sliding connection of the caliper body (5) with the support bracket (2) occurs by means of one or more sliding guides (15) according to any one of the preceding claims.

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