WO2020128825A1

WO2020128825A1 - Pad and spring assembly for disc brake and brake caliper

Info

Publication number: WO2020128825A1
Application number: PCT/IB2019/060911
Authority: WO
Inventors: Cristian Crippa; Davide D'ALESSIO; Mauro Mambretti; Andrea MECOCCI; Giuseppe SPIGAPIENA
Original assignee: Freni Brembo S.P.A.
Priority date: 2018-12-20
Filing date: 2019-12-17
Publication date: 2020-06-25
Also published as: CN113272571A; CN113272571B; IT201800020581A1

Abstract

A pad and spring assembly for a brake caliper for a disc brake, wherein an axial direction is defined either coincident with or parallel to the rotation axis of a disc (3) of said disc brake (10) which is associable with the brake caliper (2), comprising at least one brake pad, adapted to press against a facing braking surface of the disc of disc brake when pushed by thrust means of the brake caliper, at least one elastic device (5), adapted to bias said at least one brake pad with respect to the caliper body of the brake caliper in axial direction, wherein said elastic device (5) comprises at least a first portion (11) firmly fixed to the brake pad, at least a second portion (12) adapted to be associated either directly or indirectly by interposition of a metal sheet (8) with the caliper body, wherein said first portion (11) is made as a separate piece with respect to said second portion (12), said first portion (11) and said second portion (12) are mutually engaged, at least either said first portion (11) or said second portion (12) comprises an elastically deformable portion to apply an elastic biasing action adapted to make the brake pad abut against said thrust means of the brake caliper being associable with said assembly, said elastically deformable portion is an arc- shaped portion adapted to unwind to apply said elastic biasing action adapted to make the brake pad abut against said thrust means of the brake caliper being associable with said assembly; and wherein said arc-shaped portion comprises an abutment surface, adapted to form an abutment reference to elastically bias said brake pad away from the disc.

Description

DESCRIPTION

"Pad and spring assembly for disc brake and brake caliper"

[0001] . Field of the invention

[0002] . The present invention relates to a pad and spring assembly for a brake caliper.

[0003] . Moreover, the present invention relates to a brake caliper for disc brake comprising said assembly.

[0004] . Background art

[0005] . The brake caliper in a disc brake is generally arranged straddling the outer peripheral margin of a brake disc, adapted to rotate around a rotation axis defining an axial direction (X-X) . Moreover, in a disc brake there is defined a radial direction (R- R) which is substantially orthogonal to said axial direction (X- X) , and a tangential (C-C) or circumferential (C-C) direction, orthogonal both to said axial direction (X-X) and to said radial direction (R-R) .

[0006] . A brake pad comprises a plate on which a friction material is fixed, adapted to press against a facing braking surface of the braking band of the brake disc. The plate may comprise acoustic wear signalers, sometimes embedded in the friction material, which serve to emit a sound by rubbing against the braking band of the disc when the friction material is axially worn thin due to prolonged use. The axial (X-X), radial (R-R) and tangential (T-T) or circumferential (T-T) directions mean defined on a brake pad, also when it is in configuration not installed on a brake caliper.

[0007] . A known type of pad is the so-called pad of the type suspended on pins, which provides eyelets obtained in the plate of the pad and which are adapted to receive pins specifically provided in the body of the caliper which are intended to carry the pad, in which the braking action is transmitted, due to such pins, from the material of the plate which contours said eyelets to the brake caliper body.

[0008] . A different type of pads is the so-called pad of the type resting on the caliper body, which is accommodated in a specific pocket obtained in the caliper body, in which the braking action is transmitted from a side of the plate of the pad to the caliper body when said side of the plate abuts against a facing abutment surface of the pocket of the caliper body, at the start of the braking action of the vehicle. The pins associated with this type of pads serve as axial sliding guides to guide the nearing movement of the pads to the disc and to move away the pads from the disc.

[0009] . The caliper body is typically made of meatal such as aluminum, or aluminum alloy, for example aluminum and lithium, or steel, and it may be obtained by melting, but also by mechanical processing trough chip removal, as well as by forging.

[0010] . In the floating caliper bodies associated with fixed discs, a floating portion of the caliper body has a cylinder or cylinders adapted to house hydraulic pistons capable of applying a thrust action on the pad facing it, making it abut against the braking surface of the brake disc while it slides on the bracket, or fixed portion of the caliper, and acts on the second friction pad by making it abut against the opposite braking surface of the brake disc to apply the braking action on the vehicle.

[0011] . In the known fixed caliper bodies associated with fixed discs, there is a cylinder or cylinders on both axially opposite sides of the caliper body, the cylinder or cylinders being adapted to house pistons, preferably hydraulic pistons, capable of applying a thrust action on brake pads to make them abut against the respectively facing braking surfaces of the disc to apply the braking action on the vehicle.

[0012] . The pressure applied by the vehicle driver on the brake pedal applies a pressure of the brake fluid which, through a duct, is applied to the brake fluid in the hydraulic circuit arranged in the caliper body up to reaching the cylinders where the pressure is applied on the surface of the bottom of the pistons, forcing them to tighten against the brake pads, which in turn abut against the braking surfaces of the disc.

[0013] . The caliper body deforms according to the torque applied by the action of the pistons which make the pads abut against the braking surfaces of the disc, the pads being applied in directions which form torque arms with respect to the fixing points of the caliper body to the support thereof. These torques deform the caliper body also in tangential and radial direction with respect to the disc, in addition to axial direction, resulting in an increase of the stroke of the pistons, and therefore an increase of the stroke of the control pedal of the braking system.

[0014] . At the end of the braking action, the caliper body returns to its undeformed configuration, nearing the braking surfaces of the disc, and at the same time the piston of the cylinder-piston unit receives a push away from the disc by means of the action of the piston retraction devices, which usually are gaskets integrated in the dust-seal cover of the piston, as shown from documents US—2013—192936 and US—2014—231190 to the same Applicant .

[0015] . Such retraction devices of the piston (known as "roll back" devices) are typically provided at the interface between piston and respective cylinder and are designed to retract the piston inside its cylinder by a limited predefined entity, thus moving it away from the respective pad at the end of the braking control .

[0016] . Under these circumstances, the nearing of the caliper body to the disc is undesired since it causes a contact, albeit a slight contact, between brake pads and braking surfaces of the disc, which causes a continuous slight friction, and therefore a braking action known as residual braking torque, also at the end of the braking control.

[0017] . Such a residual braking torque often is considered undesired since it generates noise, albeit slight noise, caused by the friction action between pads and braking surfaces of the disc, an undesired wear of the pads and of the brake disc, and results in more frequent maintenance for the replacement thereof, and a minimum consumption of fuel to feed the drive unit also of the albeit minimum energy required to overcome this residual torque.

[0018] . For such a reason, it is known to associate the brake pads with springs which, by acting in conjunction with parts of the brake caliper body, apply a biasing action directed in axial direction (X-X) on the brake pads to move them away from the brake disc at the end of the braking action, making them abut against the pistons which have already retracted from the roll-back devices. In braking step, such a biasing action away from the disc is overcome by the thrust action applied by the pistons. Otherwise when in release step, i.e. at the end of the braking action, such springs apply a push in axial direction (X-X) aiming to move the pads away from the braking surfaces of the brake disc, thereby avoiding the contact between the pads and the brake disc when no braking action is required.

[0019] . For example, document WO-2015-155708 to the same Applicant shows a solution of cross spring coupled at the top to the bridge of the caliper body arranged straddling the disc and provided with favorably tilted portions adapted to press against radially outer portions of the brake pads to move them away from the disc. Such a spring takes advantage of the same tilted portions also for pushing the brake pad radially by acting on the radially outer edge of the brake pad. Cross spring solutions coupled to the bridge of the caliper of this type impose acting on the radially outer edge of the brake pad, thus necessarily providing a localized axial thrust which may result in a misalignment of the pads with respect to the braking surfaces of the disc facing them which, to be compensated for, generates a non-uniform wear of the friction material of the pads, thus limiting the operating life of the brake pads.

[0020] . Solutions of springs are also known which work on side extensions which project in tangential direction from the sides of the brake pad, as shown for example by document US—2014—0305753, in which the strip of the spring is folded so as to couple the brake pad with an end thereof and the caliper body with the opposite end, extending, with the folded portion, tangentially beside the plate. Such solutions impose an increased volume in tangential direction beside the pad both for accommodating the tabs of the pad and for accommodating the folded portion of the spring, thus necessarily requiring volumes of free space to be reserved in the caliper body tangentially beside the pad.

[0021] . A different known type of springs, shown for example in EP—0716246 and WO—92—18785, is located on the back of the brake pad and comprises a strip-shaped body which alternatively couples to the piston or undercuts against an elongated portion directed at the vehicle wheel of the caliper body of a floating brake caliper. For example, document US—2002—096404 shows a solution of strip spring adapted to couple in undercut manner against walls of an annular groove provided in the piston. Other solutions are known for example from US 2007/246312 Al, DE 102 38 734 Al, DE 10 2017 222639 Al, WO 2014/097098 Al and DE 84 31 730 Ul . [0022] . A further solution of a spring which is associable with the piston by shape coupling is shown in document US—2015—323024 to the same Applicant, which discloses a solution of spring comprising a plurality of tabs adapted - when inserted in a substantially cylindrical respective lightening cavity of the piston - to press against the axial walls of such a cavity.

[0023] . Solutions of spring coupled to the body of the piston have the advantage of providing the brake pad with an elastic biasing action applied in the area of the back of the pad where the one or more pistons presses, and thus they provide the possibility of substantially acting on the centroid of the brake pad. However, such known solutions are not at all lacking in drawbacks because they necessarily limit the cooling capability of the piston, and therefore of the brake fluid accommodated in the cylinder. Moreover, such springs may damage the dust-seal cover which protects the cylinder-piston unit from the penetration of dust and impurities, imposing frequent maintenance. Even in the step of replacing brake pads, as well as in the assembly step, such solutions of spring impose laborious operations for removing the whole brake caliper, accessing the pistons to couple the spring to them, or the pre-assembled pad and spring assembly, when needed.

[0024] . The need is strongly felt to provide a solution of spring to move away the brake pad from the braking surface of the disc at the end of the braking action and to make it abut against the piston, which solution is adapted to keep the pad substantially parallel to the facing braking surface of the brake disc and which at the same time avoids imposing couplings or permanent connections to the piston body.

[0025] . The need is therefore felt to provide a solution of spring to eliminate or at least minimize the residual braking torque, adapted at the same time to reduce the risk of misalignments between brake pad and braking surface of the disc facing it to promote a uniform wear of the friction material also in conditions of prolonged use, without requiring a laborious assembly .

[0026] . At the same time, the need is felt to provide a solution of spring for moving away the brake pad from the disc at the end of the braking action, which has a simplified assembly with respect to the known solutions.

[0027] . Solution

[0028] . It is an object of the present invention to obviate the drawbacks of the prior art and to provide a solution to the needs indicated with reference to the prior art .

[0029] . These and other objects are achieved by an assembly according to claim 1, as well as by a brake caliper according to claim 8.

[0030] . Certain advantageous embodiments are the subject of the dependent claims .

[0031] . Due to the solutions suggested, the brake pad can be biased against the thrust means of the brake pad, for example a piston of a cylinder-piston unit, at the end of the braking action without constraining the elastic device to the piston.

[0032] . Due to the solutions suggested, the brake pad can be biased away from the disc at the end of the braking action, thus eliminating the occurrence of the residual braking torque, and at the same time the assembly operations of the pads to the caliper body and the maintenance thereof can be simplified.

[0033] . Drawings

[0034] . Further features and advantages of the pad and spring assembly, as well as of the brake caliper, will become apparent from the description provided below of preferred embodiments thereof, given by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0035] . - figure 1 is a radially outer axonometric view of a brake caliper according to an embodiment;

[0036] . - figure 2 is a radially inner plan view of the brake caliper in figure 1;

[0037] . - figure 3 is an axonometric view of a portion of an elastic device, according to an embodiment;

[0038] . - figure 3bis is an axonometric view of a portion of an elastic device, according to an embodiment;

[0039] . - figure 4 is an axonometric view of a portion of a pad and spring assembly, according to an embodiment;

[0040] . - figure 5 is an axonometric and partial sectional view of a detail of a brake caliper comprising a pad and spring assembly according to an embodiment; [0041] . - figure 6 is an axonometric and sectional view of a portion of a brake caliper comprising a pad and spring assembly according to an embodiment, in which the cross section is obtained according to a cutting plane parallel to the axial and radial directions and passing through the straight line indicated with VI-VI in figure 2;

[0042] . - figure 7 is a sectional view of a portion of a disc brake at the end of the braking action, comprising a brake caliper comprising a pad and spring assembly according to an embodiment, in which the cross section is obtained according to a cutting plane parallel to the axial and tangential directions;

[0043] . - figure 8 is a sectional view of a brake caliper at the end of the braking action, according to an embodiment, arranged straddling a disc depicted diagrammatically, in which the cross section of the brake caliper is obtained according to a cutting plane parallel to the axial and radial directions and passing through the straight line indicated with VI-VI in figure 2;

[0044] . - figure 9 is a sectional view of a brake caliper during the braking action, according to an embodiment, arranged straddling a disc depicted diagrammatically, in which the cross section of the brake caliper is obtained according to a cutting plane parallel to the axial and radial directions and passing through the straight line indicated with VI-VI in figure 2;

[0045] . - figure 10 is a vertical raised view of a portion of an elastic device, according to an embodiment;

[0046] . - figure 11 is a sectional view of the brake caliper in figure 2, obtained according to the cutting plane XI-XI in figure

2;

[0047] . - figure 12 is an axonometric view of a portion of an elastic device, according to an embodiment;

[0048] . - figure 13 is an axonometric view of a portion of an elastic device, according to an embodiment;

[0049] . - figure 14 is an axonometric view of a portion of a pad and spring assembly, according to an embodiment;

[0050] . - figure 15 is an axonometric view of a portion of the elastic device of the pad and spring assembly according to an embodiment ;

[0051]. - figure 16 is an axonometric and partial sectional view of a detail of a brake caliper comprising a pad and spring assembly according to an embodiment;

[0052] . - figure 17 is a sectional view of a portion of a brake during the braking action, comprising a brake caliper comprising a pad and spring assembly according to an embodiment, in which the cross section is obtained according to a cutting plane parallel to the axial and tangential directions.

[0053] . Description of some preferred embodiments

[0054] . According to a general embodiment, there is provided a pad and spring assembly 1 for a brake caliper 2 for a disc brake 10.

[0055] . Defined in said disc brake 10 is an axial direction X-X either coincident with or parallel to the rotation axis of a disc

3 of the disc brake 10. Said disc brake 10 also defines a radial direction R-R which is orthogonal to the axial direction X-X, and a tangential T-T or circumferential T-T direction, orthogonal both to the axial direction X-X and to the radial direction R-R.

[0056] . Said pad and spring assembly 1 comprises at least one brake pad 4, adapted to press against a facing braking surface 13 of the disc 3 of disc brake 10 when pushed by thrust means 7 of the brake caliper 2.

[0057] . According to one embodiment, said at least one brake pad 4 comprises friction material 19 adapted to press against said facing braking surface 13 of disc 3, and a support plate 20 which supports the friction material 19, in which said support plate comprises a plate back 21 opposite to the friction material 19.

[0058] . According to a preferred embodiment, said thrust means 7 comprise at least one piston 7, for example a piston which can be actuated hydraulically and/or electro-mechanically .

[0059] . According to a preferred embodiment, said at least one piston 7 is slidingly received in at least one respective cylinder obtained in the caliper body 6 of the brake caliper 2. Said at least one respective cylinder is preferably made in one piece with the caliper body 6. According to a preferred embodiment, said caliper body 6 comprises at least one cylinder surface 22, for example having substantially cylindrical geometry, adapted to face said piston 7 when in operating conditions, thus delimiting a thrust means housing, and preferably at least one retraction device 23, or roll-back device 23, is interposed between said cylinder surface 22 and said piston 7, said retraction device being adapted to retract piston 7 in axial direction with respect to the cylinder of a predetermined entity D7 at the end of the braking control. Said cylinder walls 22 preferably delimit at least one annular trough which houses said at least one retraction device 23. According to one embodiment, said at least one annular trough delimits a deforming chamber 25 adapted to receive a portion of said retraction device 23 dragged in axial direction X- X by the movement of piston 7 in an approaching manner to disc 3 during the braking action. According to one embodiment, the extension in axial direction X-X of said deforming chamber 25 of the annular trough which receives the retraction device 23 is substantially equal to said predetermined entity D7.

[0060] . Said pad and spring assembly 1 further comprises at least one elastic device 5, adapted to bias said at least one brake pad 4 with respect to the caliper body 6 of the brake caliper 2 in axial direction X-X.

[0061] . Said elastic device 5 comprises at least a first portion

11 firmly fixed to the brake pad 4 and at least a second portion

12 adapted to be associated either directly or indirectly by interposition of a metal sheet 8 with the caliper body 6. Thereby, said first portion 11 avoids being fixed to the caliper body 6, and said second portion 12 also avoids being fixed to the brake pad 4.

[0062] . According to one embodiment, said at least a second portion 12 of the elastic device 5 is adapted to be fixed to the caliper body 6.

[0063] . According to a preferred embodiment, said at least a second portion 12 of the elastic device 5 is adapted to be indirectly associated with the caliper body 6 by interposition of a metal sheet 8. Said second portion 12 of the elastic device 5 is preferably fixed to a metal sheet 8 which in turn is associated, e.g. coupled, to the caliper body 2.

[0064] . Said second portion 12 of the elastic device 5 advantageously avoids being constrained either directly or indirectly to the thrust means 7, for example said at least one piston 7, of the brake caliper 2.

[0065] . When in operating conditions, the braking control causes the movement in axial direction X-X of piston 7 to near disc 3 with respect to the caliper body 6 which causes the axial dragging and the deformation of the piston retraction device 23. Thereby, piston 7 pushes the brake pad 4 facing it, moving it by a predefined axial advancement D4 to apply the braking action on disc 3, overcoming the elastic biasing action applied by the elastic device 5 on the brake pad 4 away from disc 3. When the braking control stops, the retraction device 23 returns to the undeformed position thereof, in other words, by retracting from the deforming chamber 25, it retracts piston 7 with respect to the cylinder by a predetermined entity D7 which is substantially equal to said predefined axial advancement D4 of the brake pad 4. At the same time, the brake pad 4 is elastically biased by the elastic device 5 to abut against piston 7, thereby moving away from the facing braking surface 13 of disc 3.

[0066] . Preferably, said predefined axial advancement D4 is equal to said predefined entity D7.

[0067] . According to a preferred embodiment, said first portion

11 of elastic device 5 is made in one piece.

[0068] . According to a preferred embodiment, said second portion

12 of elastic device 5 is made in one piece.

[0069] . Said first portion 11 of the elastic device 5 is advantageously made as a separate piece with respect to said second portion 12 of the elastic device 5. For example, said first portion 11 and said second portion 12 of the elastic device 5 are both made from a conveniently cut metal strip.

[0070] . Said first portion 11 and said second portion 12 are mutually engaged. According to a preferred embodiment, either one of said first portion 11 or said second portion 12 of the elastic device 5 comprises at least one hook 17 which engages with at least one respective engagement portion of the other of either said first portion 11 or said second portion 12.

[0071] . According to one embodiment, both said first portion 11 and said second portion 12 of the elastic device 5 comprise a hook 17 and are mutually engaged by means of the respective hook 17. In other words, each of said first portion 11 and said second portion

12 of the elastic device 5 comprises a hook 17, and said first portion 11 and said second portion 12 of the elastic device 5 are mutually engaged by means of the respective hook 17.

[0072] . According to one embodiment, said first portion 11 and said second portion 12 of the elastic device 5 are mutually engaged, preferably snap-engaged, in series .

[0073]. According to one embodiment, said brake pad 4, said first portion 11 of the elastic device 5, said second portion 12 of the elastic device 5 are connected in series in the order indicated, and said caliper body 6 is preferably connected in series to said second portion 12 of the elastic device 5 indirectly by interposition of a metal sheet 8.

[0074] . Further advantageously, at least either said first portion 11 of the elastic device 5 or said second portion 12 of the elastic device 5 comprises an elastically deformable portion to apply an elastic biasing action adapted to make the brake pad 4 abut against said thrust means 7 of the brake caliper 2 being associable with said pad and spring assembly 1. Thereby, the brake pad can abut away from the disc, against said thrust means 7, retracting it axially at the end of the braking control.

[0075] . According to one embodiment, either one of said first portion 11 or said second portion 12 of the elastic device 5 comprises said at least one hook 17 and the other of either said first portion 11 or said second portion 12 of the elastic device 5 comprises aid at least one elastically deformable portion.

[0076] . Due to the provision of such a pad and spring assembly 1, the pad can be elastically biased with respect to the caliper body 6 in axial direction X-X in an independent manner from piston

7.

[0077] . Due to the provision of such a pad and spring assembly I, the pad can be elastically biased with respect to the caliper body 6 in axial direction X-X, thus avoiding the brake pad 4 and/or the elastic device 5 from being coupled to piston 7.

[0078] . According to one embodiment, said first portion 11 of the at least one elastic device 5 is firmly fixed either near or at a definable median axis M-M or N-N of the brake pad 4.

[0079] . According to one embodiment, said at least one brake pad 4 defines a first median axis M-M which is substantially parallel to the radial direction R-R and is located substantially halfway of the volume in tangential direction T-T of the brake pad 4. In other words, said at least one brake pad 4 comprises opposite sides 26 which delimit the brake pad 4, and preferably the support plate 20, in tangential direction T-T, and said first median axis M-M is substantially equally spaced from said opposite sides 26 and preferably intersects said brake pad 4 in at least said plate back 21.

[0080] . According to one embodiment, said opposite sides 26 avoid delimiting lateral projections or lateral tabs extending tangentially away from the first median axis M-M.

[0081] . According to one embodiment, said at least one brake pad

4 defines a second median axis N-N which is orthogonal to said first median axis and substantially parallel to the tangential direction T-T .

[0082] . According to one embodiment, said at least one brake pad 4 defines a second median axis N-N which is substantially parallel to the tangential direction T-T and is located substantially halfway of the volume in radial direction R-R of the brake pad 4. In other words, said at least one brake pad 4 comprises opposite radial edges 24 which delimit the brake pad 4, and preferably the support plate 20, in radial direction R-R, and said second median axis N-N is substantially equally spaced from said opposite radial edges 24 and preferably intersects said brake pad 4 in at least said plate back 21.

[0083] . According to one embodiment, said first portion 11 of the at least one elastic device 5 is firmly fixed either near or at the intersection of said definable median axes M-M or N-N of the brake pad 4.

[0084] . According to one embodiment, said first portion 11 of the at least one elastic device 5 is firmly fixed either near or at a definable centroidal axis of the brake pad 4, thus avoiding at the same time being fixed or coupled either directly or indirectly by means of said second portion 12 of the elastic device 5, to the thrust means 7 of the brake caliper 2. The term "centroidal axis" means a portion of the brake pad 4 axially aligned with the centroid of the brake pad 4. Said centroidal axis preferably passes through the intersection of said definable median axes M-M or N-N of the brake pad 4.

[0085] . According to one embodiment, said at least one hook 17 is elastically deformable. According to a preferred embodiment, said at least one hook 17 of a portion 11 or 12 of the elastic device 5 is elastically deformable exclusively to allow the snap- engagement of the other portion 12 or 11 of the elastic device 5. Thereby, said hook 17 avoids being elastically deformed during the braking action and/or at the end of the braking action.

[0086] . According to one embodiment, said elastically deformable portion is an arc-shaped portion 9 adapted to unwind to apply said elastic biasing action adapted to make the brake pad 4 abut against said thrust means 7 of the brake caliper 2 being associable with said assembly 1. Thereby, the elastic device 5 is elastically loaded by means of the at least partial unwinding of the arc-shaped portion 9. Said arc-shaped portion 9 preferably comprises an inner surface 15 or abutment surface 15, adapted to form an abutment reference to elastically bias said brake pad 4 away from disc 3.

[0087] . According to one embodiment, said elastically deformable arc-shaped portion 9 forms a hook.

[0088] . According to one embodiment, said elastically deformable arc-shaped portion 9 is coupled to said at least one hook 17 by means of said abutment surface 15.

[0089] . According to one embodiment, at least either of said first portion 11 or said second portion 12 of the elastic device 5 comprises a ribbon-shaped body, or strip-shaped body, or tape shaped body, preferably made of spring steel. According to one embodiment, at least either of said first portion 11 or said second portion 12 of the elastic device 5 is made with an elastic strip .

[0090] . According to one embodiment, said arc-shaped portion 9 comprises ribbon-shaped body, or strip-shaped body, which is at least partially wound around a winding axis W-W to form said arc shaped portion 9 and at least partially delimiting an inner cavity 29 near or at the winding axis W-W, in which said abutment surface 15 faces the winding axis W-W. According to one embodiment, the body of at least either of said first portion 11 or said second portion 12 of the elastic device 5 is a ribbon-shaped body, or a strip-shaped body, which extends along a predefined longitudinal direction of strip-shaped body and is wound around a winding axis W-W oriented transversely to said predefined longitudinal direction of strip-shaped body.

[0091] . According to a preferred embodiment, said arc-shaped portion 9 is made in the form of a coil-shaped portion, in which the arc-shaped portion 9 is spirally wound around a winding axis W-W defining an inner coil surface or abutment surface 15, facing the winding axis W-W, and an outer surface 16, opposite to said abutment surface 15. Said coil-shaped portion preferably delimits an inner coil cavity 29 near or at the winding axis W-W, in which said abutment surface 15 faces said inner coil cavity 29. [0092] . According to one embodiment, said winding axis W-W is oriented transversely with respect to the axial direction X-X.

[0093] . According to one embodiment, as shown for example in figure 5, said winding axis W-W is oriented substantially parallel to the tangential direction T-T.

[0094] . According to one embodiment, as shown for example in figure 16, said winding axis W-W is oriented substantially parallel to the radial direction R-R.

[0095] . According to a preferred embodiment, the arc-shaped portion 9 is spirally wound around a winding axis W-W forming said coil-shaped portion and forming a predefined number of coils overlapping one another away from the winding axis W-W.

[0096] . According to a preferred embodiment, said at least one hook 17 is adapted to engage, preferably snap-engage, with said coil-shaped portion so that the abutment surface 15 acts in conjunction with said at least one hook 17 to apply said elastic biasing action adapted to make the brake pad 4 abut against said thrust means 7 of the brake caliper 2 being associable with said assembly 1.

[0097] . According to one embodiment, as shown for example in figure 16, said at least one hook 17 engages with said coil-shaped portion so that the abutment surface 15 acts in conjunction with said at least one hook 17 to apply said elastic biasing action adapted to make the brake pad 4 abut against said thrust means 7 of the brake caliper 2 being associable with said assembly 1. According to a preferred embodiment, said coil-shaped portion is fitted on hook 17, preferably with clearance. During the assembly of said assembly, the arc-shaped portion 9, preferably in the form of coil, is preferably fitted on hook 17 by means of a movement thereof in radial direction R-R away from the rotation axis of the associable brake disc 3 of disc brake. Thereby, there can be a simplified assembly of the second portion 12 on the first portion 11 of the elastic device 5.

[0098] . According to one embodiment, said hook 17 extends at the median axis M-M or N-N of the brake pad 4 and with respect thereto, is axially offset away from the brake disc 3.

[0099] . According to one embodiment, said hook 17 is made with a metal strip folded to outline a hook gap 42 which is substantially directed in radial direction R-R.

[00100] . According to one embodiment, said at least one hook comprises a longitudinal hook opening 43, directed substantially in radial direction R-R. Thereby, said hook 17 defines a an open- loop curved cross section assessed in the plane defined by the axial X-X and tangential T-T directions.

[00101] . According to one embodiment, the cross section of hook 17, assessed in the plane defined by the axial X-X and tangential T-T directions, has at least one cusp point 44 adapted to abut against said abutment surface 15 of the second portion 12 of the elastic device so as to define a minimum contact area which ideally is coincident with a radial line. The cross section of hook 17 preferably has two cusp points 44 arranged at tangentially opposite sides with respect to the winding axis W-W of the coil shaped portion.

[00102] . According to a preferred embodiment, said first portion 11 of the elastic device 5 is firmly fixed, e.g. riveted, to a substantially centroidal portion of the plate back 21 of the brake pad 4 and comprises said at least one hook 17, and preferably two opposite hooks 17, and in which said second portion 12 of the elastic device 5 forms said coil-shaped portion engaged, preferably snap-engaged, with said at least one hook 17 of the first portion 11 so that said abutment surface 15 and said at least one hook 17 reciprocally abut to bias the plate back 21 of the brake pad 4 to abut against said thrust means 7, thus avoiding to engage the elastic device to the thrust means 7. The second portion 12 of the elastic device 5 is preferably fixed to the caliper body 6 either directly or indirectly by interposition of a metal sheet 8.

[00103] . The provision of such an assembly 1 makes the abutment surface 15 of said coil-shaped portion abut with said at least one hook 17 both during the movement of the brake pad 4 moved near disc 3 by the thrust means 7, thus unwinding the coil-shaped portion, and during the retraction of the thrust means 7 in which the elastic rewinding of the coil-shaped portion around the winding axis W-W keeps the abutment surface 15 abutting with said at least one hook 17, causing the axial movement of the brake pad 4 away from the facing braking surface 13 of disc 3. Thereby, a balanced elastic biasing action can be applied, thus minimizing the risk of misalignments between brake pad 4 and disc 3, for example due to asymmetrical or unbalanced biasing actions in retraction step on various peripheral portions of the brake pad 4.

[00104] . According to one embodiment, said first portion 11 of the elastic device 5 comprises said at least one hook 17 made by cutting and folding a portion of metal strip which serves as bracket 27 extending axially from the plate back 21 of the brake pad 4.

[00105] . According to one embodiment, said first portion 11 of the elastic device comprises a pair of opposing brackets 27 comprising a pair of opposing hooks 17 extending towards each other in a direction which is transverse to the axial direction X- X to engage with said coil-shaped portion of the second portion 12 of the elastic device 5.

[00106] . According to one embodiment, said first portion 11 of the elastic device comprises a bracket 27 comprising a bracket arm which axially extends overhangingly from the plate back 21, forming a second arm directed radially and connected to hook 17.

[00107] . The distance between said opposing brackets 27 of the first portion 11 of the elastic device 5 is selected so that it is greater than the transverse extension of the strip-shaped body which forms the arc-shaped portion 9 which is preferably wound to form said coil-shaped portion - of the second portion 12 of the elastic device 5 so that said hooks 17 which extend towards one another each form a guide chute 28.

[00108] . When in assembly step, said guide chutes 28 are elastically deformed mutually away when pushed in axial direction X-X from the outer surface 16 of the coil-shaped portion to snap- engage in the inner cavity 29 delimited by the coil-shaped portion near the winding axis W-W.

[00109] . According to one embodiment, said first portion 11 of the elastic device 5 comprises a fixing portion to pad 31, which forms a firm fixing with a fixing portion 32 of the brake pad 4. According to one embodiment, the fixing portion 32 of the brake pad 4 forms an undercut housing which receives said fixing portion to pad 32 of the first portion 11 of the elastic device 5. According to one embodiment, the fixing portion of pad 31 of the first portion 11 of the elastic device 5 and the fixing portion 32 of the brake pad 4 are associated with each other by means of at least one fixing system, such as for example: at least one screw, at least one rivet, welding, or the like.

[00110] . According to one embodiment, said second portion 12 of the elastic device 5 comprises a fixing portion adapted to connect to a portion of the caliper body 6 or adapted to be fixed to a metal sheet 8, which in turn is connected to the caliper body 6.

[00111] . According to one embodiment, said arc-shaped portion 9 of the elastic device 5 is in the form of a tape or strip and comprises a first end of arc-shaped portion wound around said winding axis W-W and a second end of arc-shaped portion or fixing end adapted to be fixed, by means of at least one fixing system, either directly or indirectly by interposition of a metal sheet 8, to the caliper body 6. Said at least one fixing system preferably comprises: at least one screw, at least one rivet, welding, or the like .

[00112] . According to one embodiment, said pad and spring assembly 1 further comprises at least one metal sheet 8 adapted to connect to at least one portion of a caliper body 6 being associable with said assembly 1 and comprising at least one spring fixing portion firmly fixed to said second portion 12 of the elastic device 5. Said at least one metal sheet 8 is preferably adapted to snap-engage at least one portion of the caliper body 6. According to a preferred embodiment, said at least one metal sheet 8 comprises at least one metal sheet coupling portion 33 adapted to snap-engage at least one portion of the caliper body 6. Said metal sheet coupling portion 33 preferably comprises a shaped portion which forms a housing 34 adapted to receive a projection of the caliper body 6, thus snap-engaging therewith.

[00113] . According to one embodiment, said metal sheet substantially serves as yoke and simplifies the assembly and centering operations of the pad and spring assembly 1 to the caliper body 6.

[00114] . According to one embodiment, said second portion 12 of the elastic device 5 is fixed integral with at least one portion of said metal sheet 8, for example by means of fixing means.

[00115] . According to one embodiment, said at least one metal sheet 8 comprises at least one assembly abutment reference 35, for example a free end of metal sheet, adapted to abut against a wall of the caliper body 6 during the assembly of the brake pad 4 to which said first portion 11 of the elastic device 5 is fixed on said second portion 12 of the elastic device 5 fixed to the metal sheet 8 in turn coupled to the caliper body 6.

[00116] . Due to such an assembly 1, there can be a simplified assembly of the brake pads 4 to the caliper body 6, and therefore a quick replacement thereof with respect to known solutions. In particular, due to the provision of a brake pad 4 to which said first portion 11 of the elastic device 5 is integrally fixed, and due to a metal sheet 8 for coupling said second portion 12 of the elastic device to the caliper body 6, said brake pad 4 may be quickly coupled to said caliper body 6, avoiding the need to disassemble the thrust means 7, also allowing the brake caliper 2 to be kept in the operating position thereof arranged straddling disc 3 of disc brake 10.

[00117] . According to one embodiment, said metal sheet 8 comprises at least one elastically deformable portion. Preferably, said metal sheet 8 may be snap-engaged to said caliper body 6. According to one embodiment, said metal sheet comprises a metal sheet bridge portion 41 adapted to straddle disc 3 in the same way as a yoke, when in operating conditions. According to a preferred embodiment, said metal sheet 8 is made in one piece.

[00118] . According to a preferred embodiment, said pad and spring assembly 1 comprises: at least two opposing and facing brake pads 4, at least two opposing elastic devices 5, each elastic device 5 being associated with a respective brake pad of said at least two opposing and facing brake pads 4, and a metal sheet 8 fixed to both said at least two elastic devices 5 and adapted to straddle disc 3.

[00119] . According to a general embodiment, a brake caliper 2 for a disc brake 10 is provided.

[00120] . Said brake caliper 2 comprises a caliper body 6, adapted to straddle a disc 3 of the disc brake 10 defining an axial direction X-X either coincident with or parallel to the rotation axis of disc 3.

[00121] . Said brake caliper 2 further comprises at least one pad and spring assembly 1 according to any one of the embodiments described above.

[00122] . Said brake caliper 2 further comprises thrust means 7, for example at least one piston 7, adapted to thrust said at least one brake pad 4 to make it abut against a facing braking surface 13 of disc 3 of the disc brake 10.

[00123] . Said at least a second portion 12 of the elastic device 5 is associated either directly or indirectly by interposition of a metal sheet 8, with the caliper body 6.

[00124] . Said elastically deformable portion of at least either said first portion 11 or said second portion 12 of the elastic device 5 applies an elastic biasing action adapted to make the brake pad 4 abut against said thrust means 7 of the brake caliper

2.

[00125] . According to one embodiment, said caliper body 6 comprises two opposing elongated elements 36, respectively adapted to face either directly or indirectly, by interposition of at least one brake pad 4, opposing braking surfaces 13 of disc 3 of disc brake 10, and at least one bridge of the caliper 37 which connects said opposing elongated elements 36 to each other by straddling disc 3. According to one embodiment, each of said opposing elongated elements 36 of the caliper body 6 delimits at least one thrust means housing adapted to receive at least one portion of said thrust means 7. Thereby, said brake caliper 2 is a fixed-type of caliper.

[00126] . According to a preferred embodiment, said caliper body 6 comprises at least two thrust means housings adapted to receive each at least one piston 7 on the same elongated element 36.

[00127] . According to one embodiment, said caliper body 6 comprises an even number of thrust means housings adapted to receive each at least one piston 7 on the same elongated element 36.

[00128] . According to one embodiment, said at least one piston 7 comprises a body which delimits a piston cavity 30 open and directed towards the plate back 21, in which said piston cavity 30 is free from constraints with said elastic element 5. Thereby, there can be an improved cooling of piston 7, as well as of the brake fluid.

[00129] . According to one embodiment, said brake caliper 2 comprises one or more pad sliding pins 38 adapted to guide the movement in axial direction X-X of said at least one brake pad 4. According to one embodiment, said support plate 20 of the brake pad 4 comprises one or more pin housings 39 adapted to receive said one or more pad sliding pins 38. Said one or more pin housings 39 preferably are at least two pin housings 39 and are arranged tangentially beside said first portion 11 of the elastic device 5 firmly fixed to the brake pad 4.

[00130] . According to one embodiment, said caliper body 6 comprises at least one engagement portion 40 to the metal sheet, adapted to form an engagement abutment for at least one portion of said metal sheet 8. Said at least one engagement portion 40 to the metal sheet preferably comprises at least one projection which axially projects overhangingly, projecting towards a facing plate back 21 of said at least one brake pad 4. According to one embodiment, said housing 34 of the metal sheet 8 receives said engagement portion 40 to the metal sheet, snap-engaging therewith.

[00131] . According to a preferred embodiment, said caliper body 6 comprises at least one pad-facing wall 14, facing towards the plate back 21 of a brake pad 4 of the brake caliper 2, in which said pad-facing wall 14 extends substantially parallel to the radial R-R and tangential T-T directions, and in which said second portion 12 of the elastic device 5 is constrained either directly or indirectly by means of said metal sheet 8 to said pad-facing wall 14, avoiding to couple against an undercut wall with respect to said pad-facing wall 14 of the caliper body 6. Said pad-facing wall 14 is preferably tangentially interposed between two adjacent thrust means housings of the caliper body 6, each adapted to receive at least one piston 7 of the brake caliper 2. Thereby, said wall facing the pad is axially aligned with a substantially centroidal axis of the brake pad 4.

[00132] . Due to the above-described features provided separately from or together with one another in specific embodiments, a pad and spring assembly, as well as a brake caliper, which simultaneously meets the above-described contrasting needs and the above-mentioned desired advantages may be obtained, and in particular :

[00133] . - a substantially centroidal push of the pads away from the disc can be provided when the braking action stops, without interfering with parts of the thrust means;

[00134] . - an elastic biasing action can be provided, which is repeatable and balanced also in the case of prolonged use, substantially making the wear on various areas of the pads uniform, thus lengthening the operating life thereof;

[00135] . - at the same time, the thrust means can be cooled more effectively, and in the case, they are hydraulically operated, as well as the brake fluid; [00136] . - there can be a quick replacement of the pads because there is no need to disassemble the brake caliper from the disc.

[00137] . Those skilled in the art may make many changes and adaptations to the embodiments described above or can replace elements with others which are functionally equivalent in order to meet contingent and specific needs without however departing from the scope of the appended claims.

LIST OF REFERENCE SYMBOLS

1 Pad and spring assembly

2 Brake caliper

3 Disc

4 Brake pad

5 Elastic device

6 Caliper body

7 Thrust means or piston

8 Metal sheet

9 Arc-shaped portion

10 Disc brake

11 First portion of the elastic device

12 Second portion of the elastic device

13 Braking surface of the disc

14 Wall facing the pad of the caliper body

15 Abutment surface

16 Outer surface

17 Hook

19 Friction material of the brake pad

20 Support plate of the brake pad

21 Plate back

22 Cylinder surface of the caliper body

23 Retraction device or roll-back device

24 Radial edge of the brake pad

25 Deforming chamber

26 Side of the brake pad

27 Bracket

28 Guide housing

29 Coil cavity

30 Piston cavity

31 Fixing portion to the pad

32 Fixing portion of the pad

33 Metal sheet coupling portion

34 Metal sheet engagement housing 35 Assembly abutment reference of the metal sheet

36 Elongated element of the caliper body

37 Bridge of the caliper

38 Brake caliper pad sliding pin

39 Brake pad pin housing

40 Portion for the coupling to the metal sheet

41 Metal sheet bridge

42 Hook gap

43 Longitudinal opening

44 Hook cusp

D4 Predefined axial advancement of the brake pad

D7 Predefined entity

X-X Axial direction

R-R Radial direction

T-T Tangential direction

M-M First median axis

N-N Second median axis

Claims

1. A pad and spring assembly (1) for a brake caliper (2) for a disc brake (10), wherein an axial direction (X-X) is defined either coincident with or parallel to the rotation axis of a disc (3) of said disc brake (10) which is associable with the brake caliper (2), comprising:

- at least one brake pad (4) , adapted to press against a facing braking surface (13) of the disc (3) of disc brake (10) when pushed by thrust means (7) of the brake caliper (2);

- at least one elastic device (5), adapted to bias said at least one brake pad (4) with respect to the caliper body (6) of the brake caliper (2) in axial direction (X-X);

wherein said elastic device (5) comprises:

- at least a first portion (11) firmly fixed to the brake pad (4);

- at least a second portion (12) adapted to be associated either directly or indirectly by interposition of a metal sheet (8) with the caliper body (6);

wherein :

- said first portion (11) is made as a separate piece with respect to said second portion (12);

- said first portion (11) and said second portion (12) are mutually engaged;

- at least either said first portion (11) or said second portion (12) comprises an elastically deformable portion to apply an elastic biasing action adapted to make the brake pad (4) abut against said thrust means (7) of the brake caliper (2) being associable with said assembly (1),

characterized in that

said elastically deformable portion is an arc-shaped portion (9) adapted to unwind to apply said elastic biasing action adapted to make the brake pad (4) abut against said thrust means (7) of the brake caliper (2) being associable with said assembly (1); and wherein

said arc-shaped portion (9) comprises an abutment surface (15), adapted to form an abutment reference to elastically bias said brake pad (4) away from the disc (3) .

2 . An assembly (1) according to claim 1 , wherein said first portion (11) of the at least one elastic device (5) is firmly fixed either near or at a definable median axis (M-M or N-N) of the brake pad (4); and/or wherein

said first portion (11) of the at least one elastic device (5) is firmly fixed either near or at a definable centroidal axis of the brake pad (4), whereby avoiding at the same time to be fixed or coupled either directly or indirectly by means of said second portion (12) of the elastic device (5), to the thrust means (7) of the brake caliper (2) .

3 . An assembly (1) according to claim 1 , wherein said arc-shaped portion (9) is made in the form of a coil-shaped portion, wherein the arc-shaped portion (9) is wound around a winding axis (W-W) defining an abutment surface (15) , facing the winding axis (W-W) , and an outer coil surface (16), opposite to said abutment surface (15) .

4 . An assembly (1) according to claim 1 , wherein said arc-shaped portion (9) is made in the form of a coil-shaped portion wherein said coil-shaped portion delimits an inner cavity (29) either near or at the winding axis (W-W) , wherein said abutment surface (15) is facing said inner cavity (29); and/or wherein

- said winding axis (W-W) is oriented transversely with respect to the axial direction (X-X) , and preferably substantially parallel to the tangential direction (T-T) , or substantially parallel to the radial direction (R-R) .

5 . An assembly (1) according to any one of the preceding claims, wherein either said first portion (11) or said second portion (12) of the elastic device (5) comprises at least one hook (17) which engages with at least one respective portion, e.g. said abutment surface (15), of the other of either said first portion (11) or said second portion (12) of the elastic device (5) , so that said hook (17) avoids being elastically deformed during the braking action and/or at the end of the braking action; and/or wherein

- said at least one hook (17) of a portion (11 or 12) of the elastic device (5) is elastically deformable, preferably exclusively to allow the snap-engagement of the other portion (12 or 11) of the elastic device (5) .

6. An assembly (1) according to any one of the preceding claims, wherein at least either said first portion (11) or said second portion (12) of the elastic device (5) comprises ribbon- or strip shaped body, preferably made of spring steel.

7 . An assembly (1) according to any one of the preceding claims, further comprising at least one metal sheet (8) adapted to connect to at least one portion of a caliper body (6) which is associable with said assembly (1) and comprising at least one spring fixing portion firmly fixed to said second portion (12) of the elastic device (5); and/or wherein

- said at least one metal sheet (8) is adapted to snap-engage at least one portion of the caliper body (6); and/or wherein

- said at least one metal sheet (8) comprises at least one metal sheet coupling portion (33) adapted to snap-engage at least one portion of the caliper body (6); and/or wherein

- said metal sheet (8) comprises at least one elastically deformable portion; and/or wherein

- said metal sheet (8) comprises a metal sheet bridge portion (41) adapted to straddle the disc (3), when in operating conditions; and/or wherein

- said pad and spring assembly (1) comprises: at least two opposing and facing brake pads (4), at least two opposing elastic devices (5) , each elastic device (5) being associated with a respective brake pad of said at least two opposing and facing brake pads (4), and a metal sheet (8) fixed to both said at least two elastic devices (5) and adapted to straddle the disc (3) of the disc brake (10) .

8. A brake caliper (2) for disc brake (10) comprising:

- a caliper body (6), adapted to straddle a disc (3) of the disc brake (10) defining an axial direction (X-X) either coincident with or parallel to the rotation axis of the disc (3);

- at least one pad and spring assembly (1) according to any one of the preceding claims;

- thrust means (7) adapted to push said at least one brake pad (4) to make it abut against a facing braking surface (13) of the disc (3) of the disc brake (10) ;

wherein :

- said at least a second portion (12) of the elastic device (5) is associated either directly or indirectly by interposition of a metal sheet (8), with the caliper body (6);

- said elastically deformable portion of at least either said first portion (11) or said second portion (12) of the elastic device applies an elastic biasing action adapted to make the brake pad (4) abut against said thrust means (7) .

9 . A brake caliper (2) according to claim 8, wherein said caliper body (6) comprises two opposing elongated elements (36), respectively adapted to face either directly or indirectly, by interposition of at least one brake pad (4), opposing braking surfaces (13) of the disc (3) of disc brake (10) , and at least one bridge of the caliper (37) which connects said opposing elongated elements (36) to each other by straddling the disc (3); wherein each of said opposing elongated elements (36) of the caliper body (6) delimits at least one thrust means housing adapted to receive at least one portion of said thrust means (7), e.g. at least one piston (7); and/or wherein

- said caliper body (6) comprises an even number of thrust means housings adapted to receive each at least one piston (7) on the same elongated element (36) .

10. A brake caliper (2) according to claim 8 or 9, wherein said at least one piston (7) comprises a body which delimits a piston cavity (30) open and directed towards the plate back (21), wherein said piston cavity (30) is free from constraints with said elastic element (5); and/or wherein

said caliper body (6) comprises at least one pad-facing wall (14), facing towards the plate back (21) of a brake pad (4) of the brake caliper (2), wherein said pad-facing wall (14) extends substantially parallel to the radial (R-R) and tangential (T-T) directions, and wherein said second portion (12) of the elastic device (5) is constrained either directly or indirectly by means of said metal sheet (8) to said pad-facing wall (14), avoiding to couple against an undercut wall with respect to said pad-facing wall (14) of the caliper body (6); and/or wherein

- said pad-facing wall (14) is tangentially interposed between two adjacent thrust means housings of the caliper body (6), each adapted to receive at least one piston (7) of the brake caliper (2), so that said pad-facing wall (14) is axially aligned with a substantially centroidal axis of brake pad (4) .