Pad and spring assembly for a disc brake caliper

An assembly (1) for a disc brake caliper (100), in which, when said caliper (101) is arranged astride a disc (3) of a disc brake (100) having a defined rotation axis (C), said assembly (1) defines an axial direction (X-X) parallel to said rotation axis (C), a radial direction (R-R) orthogonal to said axial direction (X-X) and a tangential or circumferential direction (T-T) orthogonal to both the axial direction (X-X) and the radial direction (R-R), said assembly (1) comprises:

FIELD OF THE INVENTION

The present invention relates to a pad and spring assembly for a brake caliper of a brake disc.

In particular, the present invention relates to a pad and spring assembly for an asymmetric type caliper.

For example, a floating caliper of the asymmetric type comprises a caliper body and a bracket, in which the caliper body is adapted to be arranged astride the brake disc, extending from an inner side of the caliper, or side facing towards the vehicle, or support side, to an outer side of the caliper, or side facing towards the vehicle wheel, or reaction side; the bracket comprises elements for fixing the disc brake caliper to a respective support, e.g. seats or eye-bolts for accommodating screw studs or fastening bolts; the caliper body is sliding with respect to the brake along an axial direction (X-X); the caliper comprises coupling elements between the caliper body and the bracket, adapted to allow the relative sliding between caliper and bracket parallel to the axial direction (X-X); the bracket extends at the inner side of the caliper only and delimits a first seat for housing at least one first pad to exert the braking action on an inner face or inner braking surface of the brake disc. The caliper body delimits a second seat, axially opposed to the first seat but angularly offset therefrom, so as to house at least one second pad in order to exert a braking action on an outer face, or outer braking surface, of the brake disc facing towards the outer side of the caliper. The coupling means between caliper and brake comprise two guiding pins which allow and guide a relative sliding along the axial direction (X-X) of the caliper body with respect to the bracket.

BACKGROUND ART

Floating calipers, or “sliding” disc brake calipers in other words, having moveable caliper bodies on guides fixed to support brackets are known. In these known calipers, the braking action is exerted by thrust means, cylinder-piston means, positioned only on one side of the caliper body, the inner side or side facing towards the vehicle, to exert a thrust on friction elements, typically brake pads against a first braking surface which faces the inner side of the brake body.

For example, international patent application WO2012/156849 by the same applicant, shows calipers of the floating type for brake disc, in which, in order to reduce dimensions and weight, the supporting bracket is provided on only one side of the caliper, particularly on the inner side, and the sliding of the brake body with respect to the bracket, i.e. in axial direction, occurs on guiding pins.

However, because of their lightness and dimensions, the known calipers of floating type described here are subject to considerable deformation when subject to the braking action.

In particular, as known from patent FR1360566, the imbalance of the axial and tangential forces acting on the caliper body of the floating type tends to move the barycenter of the pressure areas on an associable brake disc, generating a self-locking effect of the caliper, and consequently localizing maximum wear on the side edges of the pads in contact with an associable brake disc.

The need is thus felt to compensate the imbalance of the braking action defined by the deformation of the caliper body and accentuated by the fact that the aforesaid guiding pins impose even minimum clearances in the sliding of the caliper body with respect to the bracket.

For example, from documents US2007/0256900A1, EP0145593B1, EP0489452A1 and JPH0932870A floating type calipers are known in which the pads or braking elements arranged on opposite sides of the brake caliper and facing towards opposite surfaces of an associable brake disc are arranged in misaligned position, i.e. in shifted position with respect to one another according to the circumferential coordinate of an associable brake disc, and particularly the inner braking element is arranged in advance relative to the sense of rotation of an associable brake disc. In these known solutions, a moment it thus generated on the caliper body which tends to compensate the imbalance of the braking action described above.

In particular, document US2014/0251736A1 shows a caliper of the floating type in which a set of springs of different type and shape cooperate to fix the outer braking element, or outer pad, to the central upper portion of the brake caliper.

However advantageous, such solutions do not fully solve the problem because the braking element of the outer side of the brake body, the side free from supporting bracket, is constrained in weak manner to the caliper body itself, thus being able to turn on itself and/or be arranged differently according to the degree of wear, thus thwarting at least in part the accurate design of the geometric misalignment of the opposite, facing braking elements, made to compensate for the structural deformation of the brake caliper.

Solution

It is the object of the present invention to solve the drawbacks of the prior art and to provide a solution to the need of providing a floating type caliper which is light-weight but has an accurate braking action.

Advantageously, an improved accuracy of the braking action allows to reduce the dimensions of the braking system or to obtain better braking performance, the dimensions being equal.

This and other objects are achieved by means of a pad and spring assembly for floating caliper according to claim1, as well as a floating caliper associable to a brake disc according to claims10and16, and a disc brake according to claims14and20, and a method according to claims15and21.

Some advantageous embodiments are the object of the dependent claims.

DESCRIPTION OF SOME PREFERRED EMBODIMENTS

Common elements or element parts in the embodiments described below will be indicated using the same reference numerals.

With reference to the figures, a caliper assembly for disc brake is globally indicated by reference numeral1.

An assembly1for a disc brake caliper100has, when said caliper101is arranged astride a disc3of a disc brake100having a defined rotation axis (C), an axial direction (X-X) parallel to said rotation axis (C), a radial direction (R-R) orthogonal to said axial direction (X-X) and a tangential or circumferential direction (T-T) orthogonal to both the axial direction (X-X) and to the radial direction (R-R).

Said assembly1comprises a first pad10comprising a friction material12, defining a friction surface, and a support plate13which supports said friction material12and is adapted to release the braking action onto the caliper101of the disc brake100.

Said support plate13comprises at least one lateral projection14, which extends in a direction substantially coplanar with the plate13and is placed at an end of the support plate13.

Said at least one lateral projection14is adapted to be accommodated in a pocket19obtained in the body of the caliper101.

Said assembly1further comprises at least one spring30. Said spring30is connected to said lateral projection14of said plate13.

Said spring30is adapted to be accommodated in a seat34obtained in the body of the caliper101at said pocket19.

Said seat34is delimited by at least one seat wall60.

Advantageously, said spring30is adapted to be inserted in said seat34to be fastened to said seat wall60to bias said pad10in the axial direction X-X.

Furthermore, said support plate13advantageously comprises at least one pair of opposite lateral projections14which extend in direction substantially coplanar with the plate13and are placed at opposite ends of the support plate13, and said assembly1comprises at least one pair of springs30, and each spring30is connected to each lateral projection14of said plate13.

According to a possible embodiment, not necessarily comprising all the other features presented here, each of said springs of said pair of springs30is a spring in one piece, and each of said springs30is adapted to bias the pad10with respect to the caliper101also in radial direction R-R.

According to a possible embodiment, not necessarily comprising all the other features presented here, said spring30is a leaf spring which is adapted to be press-fastened, like a clip spring, in the seat34provided in the body of the caliper101.

According to a possible embodiment, not necessarily comprising all the other features presented here, said at least one lateral projection14comprises a pin32. Said spring30comprises an opening33, e.g. a through hole, adapted to cooperate with said pin32to geometrically couple, e.g. by forcing, said spring30to the plate13.

According to a possible embodiment, not necessarily comprising all the other features presented here, each spring30of said pair of springs comprises at least two mutually opposed elastic arms51adapted to be abutted against the wall60of said seat34to fasten said spring30to said seat34by means of a force coupling, which is firm during operation, but easy to insert and remove for fast, accurate and safe replacement of the pads or in all cases for brake caliper maintenance.

According to a possible embodiment, not necessarily comprising all the other features presented here, each spring30comprises a plurality of arms51, e.g. eight arms, circumferentially distributed, like petals, and substantially protruding transverse to said lateral projection14.

According to a possible embodiment, not necessarily comprising all the other features presented here, said plurality of arms51project from an anchoring base52provided with a coupling hole33adapted to fit with interference a pin32provided on each of said lateral projections14.

According to a possible embodiment, not necessarily comprising all the other features presented here, each of said elastic arms51projects from said anchoring base52spreading to then taper towards a free end thereof to form a converging end portion53adapted to form, with an outer surface thereof facing towards the seat34, a lead-in chute for coupling the spring30to the respective seat by means of an axial movement X-X of the plate13towards the caliper.

According to a possible embodiment, not necessarily comprising all the other features presented here, each of said springs30is obtained from a sheared and bent leaf.

According to a possible embodiment, not necessarily comprising all the other features presented here, each of said seats34has a predetermined width transverse to the longitudinal extension thereof, longitudinal direction e.g. coinciding with the axial direction X-X, and in which said at least two elastic arms51are mutually opposed and, in extended condition not coupled to the seat34, have at least one portion thereof which is distanced from the opposed portion of the facing arm51by a distance which is greater than the predetermined transverse width of the seat34, so as to guarantee a force coupling between said spring30and the respective seat34, so that by entering in its seat the spring elastically compresses, folding the arms, forcing onto the walls of the seat to exert a friction action in axial direction X-X and an elastic action in radial direction R-R.

According to a possible embodiment, not necessarily comprising all the other features presented here, a caliper101comprises a caliper body2.

Said caliper body2comprises an inner side21or support side21, and an outer side11, or reaction side11.

Said outer side11comprises an inner surface37able to face a pad10and the brake disc3and an opposite outer surface38.

Said outer side11comprises at least one pocket19adapted to accommodate at least one lateral projection14of a pad10, and at least one seat34adapted to accommodate at least one spring30, and having at least one seat wall60adapted to cooperate with said spring30.

Said outer side11comprises an assembly1according to any one of the embodiments described above and adapted to face a side of an associable brake disc3.

Said inner side21comprises a second pad20opposite to the first pad10and adapted to face the opposite side of an associable brake disc3.

According to a possible embodiment, not necessarily comprising all the other features presented here, said caliper101is a floating caliper comprising a bracket4adapted to be arranged on one side of the brake disc3, said bracket4is adapted to support the caliper body2in sliding manner.

According to a possible embodiment, not necessarily comprising all the other features presented here, said pocket19is made in the form of a through hole in the caliper body2with a closed cross section.

According to a possible embodiment, not necessarily comprising all the other features presented here, said pocket19comprises walls adapted to define a guide18adapted to accommodate a protuberance17made on a portion of said pad10.

According to a possible embodiment, not necessarily comprising all the other features presented here, said pocket19is adapted to apply tangential clearance between said pad10and the walls of said pocket19.

According to a possible embodiment, not necessarily comprising all the other features presented here, said first pad10and said second pad20are adapted to be arranged substantially at the same distance from the center of rotation C of an associable brake disc3.

According to a possible embodiment, not necessarily comprising all the other features presented here, said first pad10has a first center of thrust or barycenter of the biasing actions of the pad10on the corresponding facing braking surface of the brake disc3and said second pad20has a second center of thrust or barycenter of the biasing actions of the pad20on the corresponding facing braking surface of the brake disc3. The lines R1, R2joining the projections of the first center of thrust with the rotation axis C of the brake disc3and the second center of thrust with the rotation axis C of the brake disc3, both evaluated on a plane parallel to a brake disc associable with said caliper101, mutually define a predetermined angle α.

According to a possible embodiment, not necessarily comprising all the other features presented here, a brake disc100comprises a caliper101according to any one of the embodiments described herein.

The present invention also relates to a method for installing an assembly1for a brake disc100, comprising the steps of:providing an assembly1as defined in any one of the embodiments described herein;coupling the spring30with the support plate13of the pad10;inserting the protuberance17of said pad10in the guide18obtained in the pocket19of the caliper body2;moving the pad10with respect to the guide18so as to insert said spring30into the seat34obtained in the outer side11of the caliper body2;moving the pad10in the axial direction X-X so as to couple with force said spring30against said seat wall60obtained in the caliper body2.

According to a further general embodiment of the present invention, an assembly1for a disc brake caliper100, in which, when said caliper101is arranged astride a disc3of a disc brake100having a defined rotation axis C, said assembly1defines an axial direction X-X parallel to said rotation axis C, a radial direction R-R orthogonal to said axial direction X-X and a tangential or circumferential direction T-T orthogonal to both the axial direction X-X and the radial direction R-R, said assembly1comprises a first pad10comprising a friction material12, defining a friction surface, and a support plate13which supports said friction material12and is adapted to release the braking action onto the caliper101of the disc brake100, in which said support plate13comprises at least one lateral projection14which extends in a direction substantially coplanar to the plate13and is placed at an end of the support plate13, and in which said at least one lateral projection14is adapted to be accommodated in a pocket19obtained in the body of the caliper101.

Said assembly1further comprises at least one spring30, said spring30is connected to said lateral projection14of said support plate13, and said spring30is adapted to be accommodated in a seat34formed in the body of the caliper101at said pocket19.

Said seat34is adapted to put the surface of the body of the caliper101facing the disc3into communication with an opposite surface35arranged undercut with respect to said support plate13, and in which said spring30is adapted to be at least partially interposed between said lateral projection14of the plate13and the pocket19.

Said spring30is adapted to cooperate with walls of the pocket19to bias said pad10with respect to the caliper101in the radial direction R-R.

Said assembly is characterized in that said spring30is adapted to be inserted in said seat34to be fastened in an undercut manner against the undercut surface35to bias the pad10in the axial direction X-X.

Said spring30is a spring in one piece, in which a first end31of said spring30is adapted to be at least partially interposed between said lateral projection14of the support plate13and said pocket19to bias the pad10with respect to the caliper101in the radial direction R-R, and in which a second hooked end36of said spring30is adapted to be inserted in said seat34to be fastened in an undercut manner against said undercut surface35to bias said pad10in the axial direction X-X.

Particularly, said first end31of said spring30exchanges a force Frin radial direction R-R with said walls of said pocket19and said lateral projection14of the plate13.

Particularly, said second hooked end36of said spring30is adapted to exchange a force Fxin axial direction X-X with said undercut surface35.

According to an embodiment, said spring30is a leaf spring which is adapted to be snap-fastened, like a clip spring, in an undercut manner in the body of the caliper101.

According to an embodiment, said spring30in one piece may be obtained with two or more spring portions welded firmly to one another, e.g. either riveted or welded or glued.

Advantageously, said spring30is inserted in the seat34obtained in the body of the caliper101and the coupling of the spring30to an opposite surface35arranged undercut by passing through the body of the caliper101occurs by inserting a separate component, such as for example a pin, in the body of the caliper101.

Indeed, a solution which envisages the use of a pin then coupled by a separate spring imposes a complex insertion operation of the pad, of the pin and of a separate, thus losable, component, such as, for example, a split pin, consequently making it necessary to operate on two sides of the body of the caliper101, while the invention allows to insert the pad10only on one side of the body of the caliper101, because the spring30, and particularly said second hooked end36of the spring30, is able to close by entering in the seat34to then spread in undercut manner upon exiting.

According to an embodiment, said at least one lateral projection14of the support plate13comprises a pin32, said pin32comprises a dissymmetrical cross section, and said spring30comprises a dissymmetrical opening33adapted to cooperate with said pin32to orient the position of the spring30with respect to the support plate13.

Advantageously, the dissymmetrical pin32and the opening33of the spring30cooperate to orient the relative position of the spring30and the plate13during the step of installing of the spring30on the plate13.

According to an embodiment, said spring30is made starting from laminated metallic material and is mounted on the support plate13of the pad10by means of a riveting process.

According to an embodiment, said support plate13comprises at least one pair of opposite lateral projections14which extend in direction substantially coplanar with the plate13and are placed at opposite ends of the support plate13, and said assembly1further comprises at least one pair of springs30, in which each spring30is connected to each lateral projection14of said plate13.

According to an embodiment, said caliper101comprises a caliper body2, in which said caliper body2comprises an inner side21, or support side21, or side facing the vehicle, and an outer side11, or reaction side11, or side facing the vehicle wheel.

The caliper body2may be of the single block type or may comprise a pair of half bodies9joined by means of connection means, e.g. screws or rivets. The caliper body2may further comprise a plurality of ribs5which extend astride an associable brake disc3, defining ventilation openings6between consecutive ribs.

Said outer side11comprises an inner surface37able to face a pad10and the brake disc3and an opposite outer surface38.

Said outer side11of the caliper body2comprises at least one pocket19adapted to accommodate at least one first pad10, at least one seat34adapted to accommodate at least one spring30, at least one undercut surface35with respect to said inner surface37adapted to cooperate with said second hooked end36of said spring30, and in which said outer side11comprises an assembly1as described above.

According to an embodiment, said pocket19is made in the form of a through hole in the caliper body2with a closed cross section, and said pocket19comprises walls adapted to define a guide18adapted to accommodate a protuberance17made on a portion of said pad10.

Advantageously, said protuberance17made on a portion of said pad10cooperates with said guide18contained in the caliper body2to bias the installation of said assembly1for brake disc caliper100in the caliper body2.

According to an aspect of the invention, a method for installing an assembly1for a caliper of a disc brake100in the caliper body2comprises the steps of:providing an assembly1as defined above;coupling the spring30with the support plate13of the pad10;inserting the protuberance17of said pad10in the guide18obtained in the pocket19of the caliper body2;moving the pad10with respect to the guide18so as to insert said spring30into the seat34obtained in the outer side11of the caliper body2;moving the pad10in axial direction X-X so as to snap-fasten said spring30against the undercut opposite surface35obtained in the outer side11of the caliper body2.

Advantageously, the method described above allows to install an assembly1for caliper of a brake disc100in the caliper body2simply by operating from one side of the caliper body2, and the assembly1may be installed by an operator using one hand.

According to an embodiment, a noise-deadening sheet15is arranged in contact with the support plate13of said first pad10and interposed between said support plate13and the walls of said pocket19obtained in the caliper body2.

Advantageously, said noise-deadening sheet15comprises folded shoulders16which cooperate with said pad10in tangential direction T-T in order to release the braking action on the pad10in tangential direction T-T.

According to an embodiment, said pocket19is adapted to impose a clearance in tangential direction T-T between said pad10and the walls of said pocket19to minimize the efforts in tangential direction T-T acting on the lateral projections14of the support plate13of the pad10, already burdened by the stresses in axial direction X-X and in radial direction R-R and subject to potential displacement during the braking action as a consequence of the connection to the caliper body2by means of spring30.

According to an embodiment, the inner side21of the brake body2comprises a second pad20opposite to the first pad10and facing an associable brake disc3on the opposite side.

According to an embodiment, said first pad10and said second pad20are arranged substantially at the same distance from the center of rotation C of an associable brake disc3, i.e. the braking band of an associable brake disc3is substantially the same for both pads10,20.

In particular, said first pad10has a first center of thrust or barycenter of the biasing actions of the pad10on the corresponding facing braking surface of the brake disc3, and said second pad20has a second center of thrust or barycenter of the biasing actions of the pad20on the corresponding facing braking surface of an associable brake disc3. The lines R1, R2joining the rotation axis C of an associable brake disc3and the projections of the first center of thrust and of the second center of thrust on a plane parallel to a brake disc3associable with said caliper101mutually define a predetermined angle α.

Advantageously, said misalignment of the opposite pads10,20facing opposite sides of an associable brake disc3allows to counterbalance the moment generated by the friction forces, e.g. F′ and F″, exchanged between the braking surfaces of an associable brake disc3and facing friction surfaces of pads10,20.

Advantageously, counterbalancing said moment generated by the friction forces, e.g. F′ and F″, exchanged between braking surfaces of an associable brake disc3and facing friction surfaces of pads10,20, allows to obtain a better accuracy of the braking action, the dimensions of the disc brake system100being equal, with respect to known solutions, or to reduce the dimensions of the brake disc system100, the performance level being equal.

From an analysis performed by the inventors, it arises that said misalignment biases the uniformity of the degree of wear of the friction material12of the pads10,20, in conditions of prolonged use of the braking system and depends on the choice of the value of the angle α. The choice of the value of said angle α depends on factors of geometric type, such as, for example, the thickness of a brake disc3associable to the caliper101, and may be identified either mathematically or empirically.

According to an embodiment, said caliper101is a floating caliper comprising a bracket4adapted to be arranged only on one side of the brake disc3, said bracket4is adapted to support the caliper body2in sliding manner.

Advantageously, the bracket4is adapted to be arranged only on one side of an associable brake disc3, and particularly the inner side21, or support side21, allows to make a caliper101having improved features of lightness with respect to known solutions or solutions in which the bracket4is made on both sides of the caliper101.

According to an embodiment, said bracket4is “U”-shaped, comprising a crosspiece5and an upright8to each of the opposite ends of the crosspiece7.

The crosspiece7and the uprights8at least partially delimit a seat adapted to receive at least one second pad20.

According to an embodiment, the bracket4is made of aluminum or aluminum alloy, by means of a foundry process.

According to a variant embodiment, the bracket4is made of steel or stainless steel or cast iron by means of a foundry process.

Guiding means40for the relative sliding in axial direction X-X of the caliper body with respect to the bracket4are arranged on a portion of said uprights8of said bracket4.

According to an embodiment, said guiding means40are fixed to the bracket4by means of connection devices, such as for example screws or rivets.

According to an embodiment, said guiding means40comprise a primary stud bolt41, which guides the relative sliding between caliper body2and bracket4along the axial direction, i.e. parallel to X-X, and a secondary stud bolt42, which, in addition to guiding the sliding, prevents the rotation of the caliper body2with respect to the primary stud bolt41(in known manner).

According to an embodiment, the primary and secondary stud bolts41,42are made of aluminum or aluminum alloy.

According to a variant embodiment, the primary and secondary stud bolts41,42are made of steel or stainless steel or cast iron.

According to an embodiment, a plurality of springs50is arranged on at least one portion of said uprights8and said springs50influence the sliding in axial direction X-X (in known manner).

According to an embodiment, said springs50are made of steel or stainless steel.

According to an embodiment, the disc brake system100comprises at least one actuator46acting on the second pad20, or pad positioned on the inner side21, and said actuator46may be made in form of a hydraulic piston or an electrically actuated ratio motor47and may be used for service and/or parking braking.

According to an embodiment, said caliper101is intended for applications as rear caliper for motor vehicles, such as for example cars and/or commercial vehicles, for service and/or parking braking.

According to a variant embodiment, said caliper101is intended for applications as front caliper for motor vehicles, such as for example cars and/or commercial vehicles, for service and/or parking braking.

Several changes, adaptations and replacements of elements with others which are functionally equivalent may be made by a person skilled in art to the embodiments described above in order to satisfy contingent needs without however departing from the scope of protection of the appended claims.

REFERENCES

1. Assembly2. Caliper body3. Brake disc4. Bracket5. Ribs6. Ventilation openings7. Crosspiece8. Upright9. Caliper half-body10. First pad11. Outer or reaction or wheel side12. Friction material13. Support plate14. Lateral projections of the plate15. Front noise-deadening sheet16. Folded shoulder17. Pad protuberance18. Guide19. Pocket20. Second pad21. Inner or support or vehicle side30. Spring31. First end of the spring32. Pin33. Dissymmetrical opening34. Spring seat35. Undercut surface36. Second hooked end of the spring37. Inner surface reaction side38. Outer surface reaction side40. Guiding means41. Primary stud bolt42. Secondary stud bolt46. Actuator47. Ratio motor50. Axial sliding spring51. Elastic arms52. Anchoring base53. Converging end portion60. Seat wall100. Disc brake101. CaliperX-X. Axial directionT-T. Tangential or circumferential directionR-R. Radial directionR1. Line joining the rotation axis of the brake disc and the projection of the first center of thrust of the first pad on a plane parallel to the brake discR2. Line joining the rotation axis of the brake disc and the projection of the second center of thrust of the second pad on a plane parallel to the brake disc.C. Rotation axis of the brake discα. Offset angleF′. Friction force acting on the first padF″. Friction force acting on the second padFx. Axial forceFr. Radial force