Braking system with improved robustness and mechanical strength

Abstract

The invention relates to a clamping device for a braking system intended to exert a relative displacement between friction elements with the aid of an electric actuator having a mechanism (15), for converting the rotational movement of an output shaft of the electric actuator into a translational movement, of the ball-screw type having a nut coupled to a screw (17) by balls, and a mechanism (19) for radial and / or tangential decoupling of a stop (11), intended to receive a friction element, with respect to a free end (17a) of the screw (17) of the conversion mechanism (15) in order to improve the mechanical strength of the latter (15).

Description

Braking system with improved robustness and mechanical resistance Technical field of the invention

[0001] The invention relates to the field of vehicle braking systems, more particularly electromechanical type braking systems. Technical background

[0002] A braking system of a vehicle, in particular a motor vehicle, generally comprises mechanical clamping devices comprising in particular friction elements, such as brake pads, connected to an actuator capable of bringing a pair of these friction elements together in the direction of two opposite faces of a disc secured to a wheel of the vehicle to grip it and thus brake the vehicle by friction of the friction elements against the disc, or of moving them apart in order to stop braking.

[0003] In the case of electromechanical type braking systems, the mechanical clamping devices comprise at least one electric actuator such as a motor with a rotating output shaft. Consequently, these electromechanical type mechanical clamping devices must comprise a mechanism for converting the rotational movement of the output shaft of the electric actuator into the translational movement necessary for bringing the friction elements together, which makes them more complicated than those of the hydraulic type.

[0004] Furthermore, as the braking system is used, the friction elements wear through friction against the disc. It is therefore understood that the travel of the conversion mechanism must take into account this variation in distance as the friction elements wear, i.e. the reduction in thickness.

[0005] Finally, during friction, a strong tangential stress is induced by the moving disc against the friction elements imposed in particular by the inertia of the vehicle. The end of the conversion mechanism must therefore also be sized to guarantee resistance to fatigue caused by these repeated tangential stresses.

[0006] The invention aims in particular to propose a clamping device for a braking system guaranteeing reversible clamping and loosening movements of the disc by the friction elements which are reliable, that is to say in particular whose axial stress exerted by the end of the conversion mechanism is oriented in a reproducible manner in both directions of movement, but also which are robust, that is to say whose service life is compatible with that of the vehicle without malfunction.

[0007] To this end, the invention relates to a clamping device for a braking system intended to exert a relative displacement between friction elements and comprising a frame supporting an electric actuator intended to provide the clamping force and a mechanism for converting the rotational movement of an output shaft of the electric actuator into translational movement which is coupled to the electric actuator in order to allow the relative displacement movement between the friction elements in an axial rectilinear direction, characterized in that the conversion mechanism is of the ball screw type comprising a nut coupled to a screw by balls and in that the clamping device comprises a mechanism for radial and / or tangential decoupling of a stop intended to receive a friction element relative to a free end of the screw of the conversion mechanism in order to improve the mechanical strength of the latter.

[0008] Advantageously according to the invention, the conversion mechanism allows, by the use of point connections using balls, to reduce the friction between the screw and the nut. It is therefore understood that the force transmission of the electric actuator will have a little impacted efficiency, that is to say that little force will be absorbed by the conversion mechanism. In addition, the screw is moved according to high precision movements and with negligible wear of the surfaces. Finally, the rotational movement of the output shaft of the electric actuator converted into translational movement is completely reversible between a position close to the friction elements, called contact with the disc, and a position far from the friction elements, called rest in which the friction elements do not touch the disc, making it possible to guarantee very high reliability.

[0009] Furthermore, the decoupling mechanism allows a predetermined clearance of the stop relative to the end of the screw to limit the stresses capable of crushing the screw thread and / or the external surface of at least one ball and / or the tapping of the nut. Indeed, in the contact position of the friction elements in which the screw of the conversion mechanism projects to the maximum extent relative to the frame, any stress directed outside the axial direction of the tightening-loosening movement generates an eccentric moment along the total length of the screw increasing said stress, by the lever arm phenomenon, of the end of the screw closest to the electric actuator against the balls and the nut. This is even more true in the case where the friction elements are very worn.

[0010] Advantageously according to the invention, the radial and / or tangential decoupling mechanism reduces or even eliminates any lever arm phenomenon and compensates for any eccentric moment by moving the stop relative to the screw to transmit only a negligible proportion of non-axial stresses to the balls and the nut of the conversion mechanism. It is therefore understood that the mauling and more generally the deformation of the members of the conversion mechanism are avoided in order to guarantee great robustness, that is to say in particular not having to change the clamping device for at least the duration of use of the vehicle.

[0011] The invention alternatively comprises one or more of the following optional features, taken alone or in combination.

[0012] The radial and / or tangential decoupling mechanism comprises a sliding pivot connecting element between the stop and the free end of the screw in order to limit the transmission to the balls of the conversion mechanism of the radial and / or tangential stresses received by the stop. It is therefore understood that a first degree of freedom in translation in a tangential direction (perpendicular to the axial direction and substantially parallel to the contact surfaces of the brake disc) and a degree of freedom in rotation around the same tangential direction are desired to allow, to a certain extent, the stop to “follow” the tangential direction of contact stress between the disc and the friction element by limiting the non-axial transmission of stresses to the conversion mechanism.

[0013] The sliding pivot connecting element comprises a body, a first end of which cooperates with a seat of the stop and a second end of which is fitted with play into the free end of the screw. It is therefore this part coupled to the stop which will mainly support the non-axial stresses between the disc and the friction element.

[0014] The first end of the sliding pivot connecting element has a partially spherical contact surface intended to bear against the bottom of the seat of the stop, the latter having a partially cylindrical concave surface with a circular section oriented to allow a tangential translation of the stop relative to the sliding pivot connecting element.

[0015] The first end of the sliding pivot connecting element is locked in the seat of the stop using a flange so as to limit the movement of the tangential translation of the stop relative to the sliding pivot connecting element and to only allow rotation about the tangential translation axis of the stop relative to the sliding pivot connecting element.

[0016] The decoupling mechanism is arranged to allow a tangential translation of up to two millimeters of the stop relative to the sliding pivot connecting element and a rotation about the tangential translation axis of up to two degrees of the stop relative to the sliding pivot connecting element. Similarly, the decoupling mechanism is arranged so that the clearance-fitting of the second end into the free end of the screw allows a rotation about a tangential direction of up to two degrees of the sliding pivot connecting element relative to the free end of the screw.

[0017] The inner wall of the stop seat is asymmetrical and of complementary shape with the peripheral wall of the first end of the sliding pivot connecting element in order to prevent relative rotation between the stop and the sliding pivot connecting element about the axial direction. In particular, it is possible to imagine at least one tangential direction flat present on the inner wall of the seat coupled to at least one other tangential direction flat present on the peripheral wall of the first end in order to prevent any rotation about the axial tightening / loosening direction. Of course, a polygonal section of the inner wall of the seat of a shape corresponding to that of the peripheral wall of the first end makes it possible to obtain the same effect.

[0018] The interlocking between the second end of the sliding pivot connecting element and the free end of the screw is of asymmetrical shape in order to prevent relative rotation between the free end of the screw and the sliding pivot connecting element about the axial direction. In particular, one can imagine an inner wall of the free end of the screw having a polygonal section coupled to the peripheral wall of the second end with a polygonal section of complementary shape in order to prevent any rotation about the axial tightening / loosening direction. Of course, an elliptical section of the inner wall of the free end of the screw of complementary shape to that of the peripheral wall of the second end makes it possible to obtain the same effect.

[0019] The invention also relates to a vehicle braking system comprising a pair of friction elements intended to cooperate by friction with a disc, characterized in that it comprises a clamping device as presented above arranged to bring the pair of friction elements closer together in the direction of two opposite faces of the disc in order to clamp it. The braking system is preferably of the floating caliper disc brake type.

[0020] Finally, the invention relates to a vehicle characterized in that it comprises a braking system as presented above. Brief description of the figures

[0021] Other features and advantages of the invention will emerge clearly from the description given below, for information purposes only and in no way limiting, with reference to the appended drawings, in which:

[0022] is a schematic top view of an example of a vehicle in which a braking system according to the invention is mounted;

[0023] is a schematic view of an example of a braking system according to the invention;

[0024] is a perspective view of an example of a clamping device according to the invention;

[0025] is a partial sectional view along plan IV-IV of the;

[0026] is an exploded view of an example of a decoupling mechanism according to the invention;

[0027] is a perspective view of the example decoupling mechanism according to the invention;

[0028] is an enlarged perspective view of the free end of a screw of the example conversion mechanism according to the invention;

[0029] is a front view of a flange of the example decoupling mechanism according to the invention;

[0030] is a sectional view of the example of a decoupling mechanism according to the invention according to plane IV-IV of the;

[0031] is a sectional view of the example of a decoupling mechanism according to the invention along plane XX of the. Detailed description

[0032] In all that follows, the orientations are the orientations of the figures. In particular, the terms "upper", "lower", "left", "right", "above", "below", "forward" and "backward" are generally understood in relation to the direction in which the figures are represented. However, a further distinction is made between:

[0033] - an axial direction A, coincident with the central thrust axis of the friction elements 2a, 2b;

[0034] - a radial direction R, perpendicular to the axial direction A, passing through a radius in the median plane of the disc 3; and

[0035] - a tangential direction T, perpendicular to the axial direction A, resulting from the friction by the friction elements 2a, 2b moving towards each other in the axial direction A pressing against the disc 3 rotating along an axis parallel to the axial direction A and secured to a wheel 5 of a vehicle 4.

[0036] The invention applies to any type of braking system 1, in particular those intended to equip motor vehicles 4 of the passenger car type, SUV (“Sport Utility Vehicle”), two-wheelers (in particular motorcycles), airplanes, industrial vehicles chosen from vans, “Heavy Goods Vehicles” - i.e. metro, bus, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering vehicles -, or other transport or handling vehicles. The invention also applies to non-motorized vehicles such as in particular a trailer, a semi-trailer or a caravan.

[0037] By "electromechanical type braking system 1" is meant all types of braking systems 1 comprising at least one electric actuator 12 intended to bring friction elements 2a, 2b together in order to laterally pinch a disc 3 integral in rotation with a wheel 5 of vehicle 4 to brake it.

[0038] In the examples of Figures 2 to 3, a braking system 1 with a clamping device 7 of the floating caliper type is used, that is to say that a frame 8, or brake, has an electric actuator 12 on only one side and is formed of a yoke 9 fixed relative to the vehicle 4 and a caliper 10 movable relative to the yoke 9 arranged to bring the friction element 2b closer once the friction element 2a is in contact with the disc 3. Such a clamping device 7 of the floating caliper type makes it possible to use fewer electric actuators 12 and thus to be more compact.

[0039] Of course, the invention also applies to a braking system 1 with a clamping device 7 of the fixed caliper type, that is to say that a frame 8, formed of a caliper 10 fixed relative to the vehicle 4, comprises an electric actuator 12 for each element 2a, 2b on each side of the disc 3 to bring the friction elements 2a, 2b together respectively in order to come into contact with the disc 3.

[0040] In the example illustrated in Figures 2 to 10, the invention relates to a clamping device 7 intended to exert a relative movement in the axial direction A between friction elements 2a, 2b. A stop 11 is intended to receive a friction element 2a, 2b, such as at least one brake pad, in the manner of a hydraulic system piston. The stop 11 comprises at least one groove 11a making it possible to cooperate with the friction element 2a, 2b without possible rotation about the axial direction A in a direct manner (no intermediate part such as for example an external rib of the friction element 2a, 2b) or indirect manner (intermediate part used such as for example a key between the friction element 2a, 2b and the stop 11).

[0041] The clamping device 7 comprises a frame 8 supporting an electric actuator 12 intended to provide the clamping force by the stop 11 and all the associated power and control members in order in particular to manage the amplitude and the approach force. The frame 8 also receives a mechanism 15 for converting the rotational movement of an output shaft 13 of the electric actuator 12 into translational movement in the axial direction A. In the example illustrated in 1, the conversion mechanism 15 is coupled to the electric actuator 12 using a reduction gear 14. A relative displacement movement is therefore obtained between the friction elements 2a, 2b in a substantially axial rectilinear direction A.

[0042] Advantageously according to the invention, the conversion mechanism 15 is of the ball screw type. The conversion mechanism 15 mainly comprises a nut 16, a screw 17 and balls 18. The free end 17a of the screw 17 is moved by translation in the axial direction A thanks to the external thread of the screw 17 which is coupled to the tapping of the nut 16 by means of balls 18. The rotation of the nut 16 is controlled when the output shaft 13 of the electric actuator 12 imparts a rotation. The endless screw 17 is also driven in rotation by guiding the balls 18 in the nut 16 by generating a translational movement of the free end 17a of the screw 17 relative to the frame 8 in the axial direction A.

[0043] Advantageously according to the invention, the conversion mechanism 15 makes it possible, by the use of point connections using the balls 18, to reduce the friction between the screw 17 and the nut 16. It is therefore understood that the force transmission of the electric actuator 12 will have little impact on performance, that is to say that little force will be absorbed by the conversion mechanism 15. In addition, the screw 17 is moved according to movements of great precision and with negligible wear of the surfaces. Finally, the rotational movement of the output shaft 13 of the electric actuator 12 converted into translational movement in the axial direction A is completely reversible between a position close to the friction elements 2a, 2b, called contact with the disc 3, and a position distant from the friction elements 2a, 2b, called rest in which the friction elements 2a, 2b do not touch the disc 3 illustrated in the, making it possible to guarantee very high reliability.In a known manner, a translation by a distance dependent on the wear, i.e. the thickness, of the elements 2a, 2b is carried out between the contact position and the rest position.

[0044] Advantageously according to the invention, the clamping device 7 comprises a mechanism 19 for radial and / or tangential decoupling of the stop 11 intended to receive a friction element 2a, 2b relative to the free end 17a of the screw 17 of the conversion mechanism 15 in order to improve the mechanical strength of the latter. Indeed, the decoupling mechanism 19 makes it possible to authorize a predetermined movement, that is to say preferably two degrees of freedom, of the stop 11 relative to the end 17a of the screw 17 making it possible to limit the stresses capable of crushing the screw thread 17 and / or the external surface of at least one ball 18 and / or the tapping of the nut 16.

[0045] Indeed, in the contact position of the friction elements 2a, 2b in which the screw 17 of the conversion mechanism 15 projects to the maximum extent relative to the frame 8, any stress directed outside the axial direction A of the tightening-loosening movement generates an eccentric moment along the total length of the screw 17 increasing said stress, by the lever arm phenomenon, of the end of the screw 17 closest to the electric actuator 12 against the balls 18 and the nut 16. This is even more true in the case where the friction elements 2a, 2b are very worn in which the translation distance is increased by amplifying the lever arm phenomenon. The radial and especially tangential stresses result from friction of the friction elements 2a, 2b on the disc 3.

[0046] Advantageously according to the invention, the radial and / or tangential decoupling mechanism 15 reduces or even eliminates any lever arm phenomenon and compensates for any eccentric moment by moving the stop 11 relative to the screw 17 to transmit only a negligible proportion of non-axial stresses to the balls 18 and to the nut 16 of the conversion mechanism 15. It is therefore understood that the mauling and, more generally, the deformation of the members of the conversion mechanism 15 are avoided in order to guarantee great robustness, that is to say in particular not having to change the clamping device 7 for at least the duration of use of the vehicle 4.

[0047] The radial and / or tangential decoupling mechanism 19 comprises a connecting element 21 and a flange 23. The element 21 preferably forms at least one sliding pivot type connection between the stop 11 and the free end 17a of the screw 17 in order to limit the transmission to the balls 18 of the conversion mechanism 15 of the radial and / or tangential stresses received by the stop 11.

[0048] It is therefore understood that a first degree of freedom in translation β, -β is desired along a tangential direction T (perpendicular to the axial direction A as illustrated in particular in the) and a degree of freedom in rotation α, -α around the same tangential direction T (as illustrated in particular in the) to allow, to a certain extent, the stop 11 to “follow” the radial and / or tangential directions of contact stress between the disc 3 and the friction element 2a, 2b by limiting the non-axial transmission of stresses to the conversion mechanism 15.

[0049] The sliding pivot connecting element 21 thus comprises an elongated body 21a of generally cylindrical shape intended to articulate the stop 11 relative to the free end 17a of the screw 17. As illustrated in the example of figures 5-6 and 9-10, the body 21a comprises a first end 20 whose contact surface 20a is intended to bear against the bottom 24c of a seat 24 of the stop 11. The contact surface 20a is preferably of partially spherical shape and the bottom 24c of the seat 24 of the stop 11 preferably has a partially cylindrical concave surface with a circular section oriented to allow a tangential translation β, -β of the stop 11 relative to the sliding pivot connecting element 21 but also in particular a rotation α, -α around the same tangential direction T as the translation.It is therefore this connecting element 21 coupled to the stop 11 which will mainly support the non-axial stresses between the disc 3 and the friction element 2a, 2b.

[0050] In order to prevent rotation around the radial direction and to limit the tangential translation β, -β and rotation α, -α, the first end 20 of the sliding pivot connecting element 21 is blocked in the seat 24 of the stop 11 using a flange 23. More precisely, the flange 23 comprises a generally annular body 23a whose central opening 23d receives the body 21a of the connecting element 21. The body 23a comprises a collar forming an attachment element 23e against the external surface of the ring 11c formed by the annular recess 11b in the stop 11. It is understood that the contact surface 20a is held against the bottom 24c of the seat 24 of the stop 11 by elastic fitting of the internal diameter of the attachment element 23e against the external diameter of the ring 11c.

[0051] Preferably, the decoupling mechanism 19 is arranged to allow a tangential translation β, -β of up to two millimeters of the stop 11 relative to the sliding pivot connecting element 21, that is to say the maximum possible movement (between β and -β) of the connecting element 21 in the tangential direction in the opening 23d of the flange 23 by abutment of the peripheral wall 20b against respectively the translation limiting elements 23c of the flange 23.

[0052] Furthermore, the decoupling mechanism 19 is arranged to allow a rotation α, -α about the tangential translation axis T up to two degrees of the stop 11 relative to the sliding pivot connecting element 21, i.e. the maximum possible angular displacement (between α and -α) of the connecting element 21 about the tangential direction T in the opening 23d of the flange 23 by abutment of the rear surface 20c against respectively the rotation limiting elements 23b of the flange 23. It is also noted that the complementary shapes of the rear surface 20c and the rotation limiting elements 23b limit or even prevent the radial rotation and the axial and radial translations of the stop 11 relative to the connecting element 21 which promotes the tangential translation β, -β.

[0053] Finally, in order to prevent relative rotation between the stop 11 and the sliding pivot connecting element 21 about the axial direction A, the inner wall 24a, 24b of the seat 24 of the stop 11 is asymmetrical and of complementary shape with the peripheral wall 20b of the first end 20 of the sliding pivot connecting element 21. In the example illustrated in Figures 5-6 and 9-10, the inner wall comprises at least one part 24a (two parallel parts 24a visible in the) forming a flat in a tangential direction, that is to say a flat surface, of complementary shape with a flat of the peripheral wall 20b of the connecting element 21 in order to prevent any rotation about the axial tightening / loosening direction A.

[0054] In the example illustrated in 1, the two parallel parts 24a are connected to each other laterally by parts 24b in an arc of a circle to form an internal wall of the seat 24 which extends around the bottom 24c. The parts 24b in an arc of a circle do not necessarily have to be of a shape complementary to the peripheral wall 20b of the connecting element 21 because they are not intended to come into contact with it; it is the elements 23c for limiting the translation of the flange 23 which have this function as suggested in 1. Of course, a polygonal section of the internal wall of the seat 24 of a shape corresponding to that of the peripheral wall 20b of the first end 20 would make it possible to obtain the same effect.

[0055] As illustrated in the example shown in Figures 5-7 and 9-10, the body 21a comprises a second end 22 intended to be fitted with play into the free end 17a of the screw 17. More precisely, the contact surface 22a and the peripheral wall 22b of the second end 22 preferably have shapes complementary respectively to the bottom 17c and to the internal wall 17b of the free end 17a of the screw 17 in order to prevent relative rotation between the free end 17a of the screw 17 and the sliding pivot connecting element 21 around the axial direction but to allow relative tangential γ, -γ and radial δ, -δ rotations between the connecting element 21 and the screw 17 in order in particular to be able to "follow" the movements of the sliding pivot connection of the first end 20.

[0056] In the example illustrated in Figures 5-7 and 9-10, the contact surface 22a and the bottom 17c are of complementary partially spherical shapes, respectively convex and concave, in order, thanks to the clearances of the fitting, to allow, to a certain extent, relative tangential γ, -γ and radial δ, -δ rotations between the connecting element 21 and the screw 17. The decoupling mechanism 19 is arranged to allow relative tangential γ, -γ and radial δ, -δ rotations between the connecting element 21 and the screw 17 up to two degrees, that is to say the maximum possible angular displacement (between γ and -γ and between δ and -δ) of the connecting element 21 respectively around the tangential direction T and the radial direction R by abutment of the peripheral wall 22b of the connecting element 21 against the internal wall 17b of the free end 17a of the screw 17.

[0057] In addition, the sections of the peripheral wall 22b of the second end 22 and of the internal wall 17b of the free end 17a of the screw 17 are of complementary asymmetrical shapes in order to prevent relative rotation between the free end 17a of the screw 17 and the sliding pivot connecting element 21 about the axial direction A. In the example illustrated in Figures 5-7 and 9-10, the sections of the peripheral wall 22b of the second end 22 and of the internal wall 17b of the free end 17a of the screw 17 are polygonal (octagonal in Figures 5 and 7). Of course, an elliptical section of the internal wall 17b of the free end 17a of the screw 17 of a shape complementary to that of the peripheral wall 22b of the second end 22 makes it possible to obtain the same effect.

[0058] The invention is not limited to the embodiments and variants presented and other embodiments and variants will become clear to those skilled in the art. Thus, the embodiments and variants can be combined with one another without departing from the scope of the invention. By way of non-limiting example, other geometries of the connecting element 21 and / or the seat 24 and / or the interlocking between the free end 17a of the screw 17 and the connecting element 21 are possible, or even the sliding pivot connection can be interchanged with the interlocking connection with play without departing from the scope of the invention.

[0059] List of references

[0060] 1 - braking system

[0061] 2a - friction element

[0062] 2b - friction element

[0063] 3 - disc

[0064] 4 - vehicle

[0065] 5 - wheel

[0066] 7 - clamping device

[0067] 8 - built

[0068] 9 - screed

[0069] 10 - stirrup

[0070] 11 - stop

[0071] 11a - groove

[0072] 11b - annular recess

[0073] 11c - attachment ring

[0074] 12 - electric actuator

[0075] 13 - output shaft

[0076] 14 - reduction gear

[0077] 15 - conversion mechanism

[0078] 16 - nut

[0079] 17 - screw

[0080] 17a - free end of screw

[0081] 17b - inner wall of the free end of the screw

[0082] 17c - bottom of the free end of the screw

[0083] 18 - marbles

[0084] 19 - radial and / or tangential decoupling mechanism

[0085] 20 - first end of the connecting element

[0086] 20a - contact surface of the first end

[0087] 20b - peripheral wall of the first end

[0088] 20c - back surface of first end

[0089] 21 - connecting element

[0090] 21a - body of the connecting element

[0091] 22 - second end of the connecting element

[0092] 22a - contact surface of the second end

[0093] 22b - peripheral wall of the second end

[0094] 23 - flange

[0095] 23a - flange body

[0096] 23b - flange rotation limiting element

[0097] 23c - flange translation limiting element

[0098] 23d - opening the flange

[0099] 23rd - bridle attachment element

[0100] 24 - stopper seat

[0101] 24a - part of the internal wall forming a flat in a tangential direction

[0102] 24b - part of the inner wall in an arc of a circle

[0103] 24c - bottom of the stopper seat

[0104] α - relative tangential rotation between the connecting element and the stop

[0105] β - relative tangential translation between the connecting element and the stop

[0106] γ - relative tangential rotation between the connecting element and the screw

[0107] δ - relative radial rotation between the connecting element and the stop

Claims

Clamping device (7) for a braking system (1) intended to exert a relative displacement between friction elements (2a, 2b) and comprising a frame (8) supporting an electric actuator (12) intended to provide the clamping force and a mechanism (15) for converting the rotational motion of an output shaft (13) of the electric actuator (12) into translational motion which is coupled to the electric actuator (12) in order to allow the relative displacement between the friction elements (2a, 2b) in a rectilinear axial direction (A), characterized in that the conversion mechanism (15) is of the ball screw type comprising a nut (16) coupled to a screw (17) by balls (18) and in that the clamping device (7) comprises a radial and / or tangential decoupling mechanism (19) of a stop (11) intended to receive an element (2a,2b) friction relative to a free end (17a) of the screw (17) of the conversion mechanism (15) in order to improve the mechanical strength of the latter (15). Clamping device (7) according to the preceding claim, in which the radial and / or tangential decoupling mechanism (19) comprises a sliding pivot linking element (21) between the stop (11) and the free end of the screw (17) in order to limit the transmission to the balls (18) of the conversion mechanism (15) of the radial and / or tangential stresses received by the stop (11). Clamping device (7) according to the preceding claim, in which the sliding pivot connecting element (21) comprises a body (21a) of which a first end (20) cooperates with a seat (24) of the stop (11) and of which a second end (22) is fitted with clearance into the free end (17a) of the screw (17). Clamping device (7) according to the preceding claim, in which the first end (20) of the sliding pivot connecting element (21) has a partially spherical contact surface (20a) intended to bear against the bottom (24c) of the seat (24) of the stop (11), the latter (24c) having a partially cylindrical concave surface with a circular cross-section oriented to allow a tangential translation (β, -β) of the stop (11) relative to the sliding pivot connecting element (21). Clamping device (7) according to the preceding claim, in which the first end (20) of the sliding pivot connecting element (21) is locked in the seat (24) of the stop (11) by means of a flange (23) so as to limit the tangential translation (β, -β) of the stop (11) relative to the sliding pivot connecting element (21) and the rotation (α, -α) around the axis (T) of tangential translation (β, -β) of the stop (11) relative to the sliding pivot connecting element (21). clamping device (7) according to the preceding claim, wherein the decoupling mechanism (19) is arranged to permit a tangential translation (β, -β) up to 2 mm of the stop (11) relative to the sliding pivot connecting element (21) and a rotation (α, -α) around the axis (T) of tangential translation (α, -α) up to 2° of the stop (11) relative to the sliding pivot connecting element (21). Clamping device (7) according to any one of claims 3 to 6, wherein the inner wall (24a, 24b) of the seat (24) of the stop (11) is asymmetric and of complementary shape with the peripheral wall (20b) of the first end (20) of the sliding pivot connecting element (21) in order to prevent relative rotation between the stop (11) and the sliding pivot connecting element (21) around the axial direction (A). Clamping device (7) according to any one of claims 3 to 7, wherein the fit between the second end (22) of the sliding pivot connecting element (21) and the free end (17a) of the screw (17) is of complementary shape in order to prevent relative rotation between the free end (17a) of the screw (17) and the sliding pivot connecting element (21) around the axial direction (A). Vehicle braking system (1) comprising a pair of friction elements (2a, 2b) intended to cooperate by friction with a disc (3), characterized in that it comprises at least one clamping device (7) according to any one of the preceding claims for bringing the pair of friction elements (2a, 2b) closer to two opposite faces of the disc (3) in order to clamp it. Braking system (1) according to the preceding claim, being of the type floating caliper disc brake. Vehicle (4) characterized in that it comprises at least one braking system (1) according to claim 9 or 10.

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