motor vehicle.

Abstract

The invention relates to a disc brake (F) comprising a caliper (E) having opposite each other a fixed brake pad (P1) and a movable brake pad (P2) relative to the caliper (E), and an actuation mechanism for the movable brake pad (P2) comprising a screw / nut system and means for transmitting a rotational movement from a drive pinion (5) to the screw / nut system to actuate the movable brake pad (P2).The invention consists in the fact that the screw / nut system is mounted in a housing (L) formed in the caliper (E), the screw (1) of the screw-nut mechanism being fixed in translation within said housing (L) and rotatable by the transmission means, while the nut (2) mounted fixed in rotation within said housing (L) is rotatable along the screw (1) when the latter is rotated, the translational movement of the nut (2) in a first direction allowing the movable brake pad (P2) to be moved towards the fixed brake pad (P1) and the translational movement of the nut (2) in the opposite direction allowing the movable brake pad (P2) to be moved away from the fixed brake pad (P1). Figure 1.

Description

Title of the invention: Disc brake, in particular for a motor vehicle.

[0001] The invention relates to a disc brake, in particular for a motor vehicle, comprising a caliper, capable of spanning a sector of a disc secured to a wheel of said vehicle, so as to position a brake pad on each side of the disc, with means for controlling the tightening of the brake pads on the disc. Such a disc brake comprises a caliper comprising, facing each other, a fixed brake pad and a brake pad movable relative to the caliper, as well as a mechanism for actuating the movable brake pad comprising a screw / nut system and means for transmitting a rotational movement from a drive shaft to the screw / nut system to actuate the movable brake pad.

[0002] State of the art.

[0003] In a disc brake, a caliper is rotationally fixed to the vehicle, for example to the steering knuckle forming the wheel hub. The caliper generally comprises two branches connected to each other by an arch, and spans a sector of a disc which is fixed to the wheel, with one branch on each side of the disc. The caliper grips the disc between its branches by means of a pair of friction linings, or brake pads, one on each side of the disc. For braking, these pads are clamped against the disc by the action of one or more brake pistons, actuated either by hydraulic pressure when used as a service brake or by electromechanical means when used as a parking brake. This clamping thus creates friction between the brake pads and the disc, which dissipates the kinetic energy of the vehicle in the form of heat and achieves braking.

[0004] The service brake function consists of slowing down the vehicle when it is in motion, if necessary until it comes to a complete stop. In addition to the service brake, such a disc brake can be implemented to also perform an emergency brake function and / or a parking brake, also called a parking brake.

[0005] In the case where the disc brake comprises electromechanical means for actuating said brake, said electromechanical means comprise on the one hand a screw / nut group and on the other hand an electric motor-reducer assembly for rotating in both directions the nut of the screw-nut group. A disc brake of this type is, for example, described in FR-A-3 116 576.

[0006] The caliper in this document has two branches, one carrying a fixed brake pad and the other a movable brake pad arranged opposite each other, the movable brake pad being driven in movement towards the fixed part using of an electromechanical actuator comprising a ball screw-nut system and a rotational control interface from a motor.

[0007] The nut is mounted fixed in translation in a housing of the branch of the caliper and its rotational drive by the rotational control interface of the motor generates the translational movement of the screw, one end of which is connected to the movable brake pad.

[0008] Thus, the rotational drive of the nut in a first direction causes the translation of the screw projecting from the branch of the caliper and therefore the translational drive of the movable brake pad in the direction of the fixed brake pad, to control the tightening of the disc while the rotational drive of the nut in the opposite direction causes the translational movement of the screw in the opposite direction and therefore the separation of the movable brake pad to control the loosening.

[0009] A brake such as described above, however, has a complex structure and is also relatively bulky, linked in particular to the interface between the motor shaft and the nut.

[0010] The invention therefore aims to propose a disc brake of this type in which the structure is simpler and therefore has a reduced size.

[0011] The invention relates to a disc brake comprising a caliper comprising, opposite one another, a fixed brake pad and a movable brake pad, as well as a mechanism for actuating the movable brake pad comprising a screw / nut system and means for transmitting a rotational movement of a drive pinion to the screw / nut system to actuate the movable brake pad, characterized in that the screw / nut system is mounted in a housing provided in the caliper, the screw of the screw-nut mechanism being mounted fixed in translation in said housing and drivable in rotation by the transmission means, while the nut mounted fixed in rotation in said housing is drivable in translation along the screw when the latter is driven in rotation,the translational drive of the nut in a first direction allowing the movable brake pad to be driven in translation towards the fixed brake pad and the translational drive of the nut in the opposite direction allowing the movable brake pad to be moved away from the fixed brake pad.

[0012] Thus advantageously, the rotational drive of the screw, fixed in translation, under the effect of the actuation of the motor pinion causes the translational movement of the nut which is itself fixed in rotation. The screw being the element of the screw-nut mechanism which is driven by the motor pinion, the means for transmitting the rotation of the motor pinion to the screw requires a smaller number of parts and less bulky than those necessary to transmit the rotation of the motor pinion to a nut.

[0013] The brake according to the invention therefore has a simplified, more compact, and therefore less expensive structure.

[0014] The brake comprises a caliper having two branches defining a space between them, so that the brake is thus mounted overlapping on a disc secured to a wheel, a sector of the disc being thus housed between the branches of the caliper each carrying a brake pad. One of the brake pads, called mobile, can be driven in movement relative to the other pad, called fixed, guided in translation along an axis XX- perpendicular to the disc interposed between the brake pads, in a tightening or loosening action.

[0015] One of the branches of the caliper therefore comprises the housing in which the screw-nut system of the mechanism for actuating the movable brake pad is mounted, this cylindrical housing with circular section is open at one end in the space between said branches and accommodates at its other end at least in part, the means for transmitting the rotation of the motor pinion to the screw.

[0016] Said housing thus has at least one bore having dimensions complementary to the nut of the screw-nut system, said bore comprising fixing means complementary to fixing means provided on the nut, allowing said nut to be mounted fixed in rotation and movable in translation in the housing.

[0017] Thus, these mounting means comprise, for example, at least one axial rib extending on the external wall of the nut along its longitudinal axis and an axial groove formed correspondingly in the wall of the housing of the fixed part, the axial rib of the nut being engageable in the axial groove formed in the wall of the housing, which blocks the nut from rotating in the housing but allows it to be driven in translation, along the groove. It is possible to envisage the rib on the wall of the housing and the groove on the nut.

[0018] The means for transmitting a rotational movement from a motor pinion to the screw / nut system are also housed in said housing. These transmission means are successively constituted, from the motor shaft, by a motor pinion, a planet carrier, and a crown. The crown is integral with both the planet carrier and the screw of the screw / nut system. Thus, this crown is made in one piece with the screw, for example constituting the end of the screw whose other end is engaged in the nut. Preferably, the screw / nut system consists of a ball screw / nut system. A cover covers the electric motor and includes the means for controlling said motor.

[0019] Thus, advantageously, the nut is preferably in the form of a cylindrical sleeve surrounding the screw, having a thread on its inner wall, engaged with the screw, and locked in rotation in the housing, said nut being driven in translation under the effect of the rotational drive of the screw by the drive shaft. The end of the nut intended to protrude into the space between the arms of the caliper, during translational drive, rests against the movable brake pad and allows the latter to be driven in movement.

[0020] Preferably, at this end of the nut is mounted in a sealed manner a cap. The nut carrying the cap then acts as a piston driven in translation by the screw and moved in abutment against the movable brake pad, towards the fixed brake pad in one direction of rotation of the screw and back in the opposite direction of rotation. The cylindrical nut provided with its end cap thus has a piston shape, making it possible to apply a better distributed axial thrust on the movable brake pad.

[0021] A sealing bellows is also fixed between the periphery of the housing and the cap, making it possible to guarantee the sealing of said housing during the movement of said piston nut.

[0022] Advantageously, the cap has a cylindrical skirt engaged at the end of the nut and which comes into sealed abutment against the periphery of the housing, when the movable brake pad is in the position spaced from the fixed brake pad, in the loosening position while a sealing bellows is fixed between the caliper (around the periphery of the housing) and the cap so that when the nut is driven towards the tightening position of the brake pad, the bellows maintains the sealing of the housing.

[0023] Advantageously, the screw-nut system, the cap and the sealing bellows are assembled in the form of a module which can be inserted into the housing provided in the stirrup.

[0024] The movable brake pad is mounted integral with the nut or independently.

[0025] The brake according to the invention makes it possible to limit the size linked to the interface between the motor pinion and the screw / nut system, which also makes it possible to reduce the number of parts required and, in addition, no radial force is supported by the screw and the interface, the nut behaving like a hydraulic type piston.

[0026] The present invention also relates to a motor vehicle equipped with disc brakes according to the invention.

[0027] The invention also relates to a method of manufacturing a brake according to the invention, in which a through bore is made in one of the branches of the caliper to form a housing opening into the space between the branches, the screw / nut system is mounted in said housing, one end of the screw is connected to the means for transmitting the rotational movement of a motor pinion connected to an electric motor while the end of the nut is fixed to the movable brake pad.

[0028] The invention will now be described in more detail with reference to the drawing in which the figures represent:

[0029] [Fig.l] a longitudinal sectional view of a disc brake according to the invention;

[0030] [Fig.2] a side perspective view of a screw / nut system of a brake according to the [Fig.l];

[0031] [Fig.3] a longitudinal sectional view of the screw / nut system according to [Fig.2] and

[0032] [Fig.4] a perspective view of a disc brake according to the invention.

[0033] As can be seen in [Fig.l], the invention relates to a disc brake F comprising a caliper E intended to span a sector of a disc which is rotationally fixed to a vehicle wheel, for example on the hub.

[0034] This caliper E comprises two branches B1, B2 defining between them a space E1 in which brake pads P1, P2 extend opposite each other, intended to be located on either side of the disc sector.

[0035] One branch of the caliper B1, also called the nose of the caliper E, carries the fixed brake pad PI while the second branch B2 carries the mobile brake pad P2.

[0036] Branch B2 comprises a through bore defining a housing L in which is housed a screw / nut system actuated by a geared motor. This screw / nut system is preferably made up of a ball screw / nut assembly, comprising a screw 1, a nut 2 forming a ball screw and balls 3 engaged in threads of the screw 1 and the nut 2.

[0037] Thus, the screw 1 and the nut 2 extend into the housing L. The screw 1 is mounted to be driven in rotation under the effect of a geared motor and fixed in translation while the nut 2 is mounted fixed in rotation in said housing L and movable in translation in said housing L under the effect of the rotational drive of the screw 1.

[0038] Means for transmitting the rotational movement of a motor pinion 5 allow the rotational drive of the screw 1 and are for example successively constituted, from the motor shaft 4, by a motor pinion 5, a planet carrier 6, and a crown 7. The crown 7 is integral with both the planet carrier 6 and the screw 1. Thus, this crown 7 is made in one piece with the screw 1, for example by constituting the end of the screw 1.

[0039] The satellite pinions 8 located radially between the planet carrier 6 and the crown 7 ensure the irreversibility of the movements transmitted inside the brake F.

[0040] The motor pinion 5 is fixed to the motor shaft 4, and the planet carrier 6 meshes with the motor pinion 5 as well as the crown 7 by two circles of planet pinions 8. The screw 1 is fixed to the crown 7.

[0041] As a result, when the crown 7 is driven in rotation under the effect of the motor pinion 5, the screw 1 is driven in rotation. The nut 2, held fixed in rotation in the housing L, is then driven in translation along the screw 1.

[0042] At the end of this nut 2 is fixed a cap 9 integral with the plate of mobile braking P2. Thus, in a first direction of rotation of the screw 1, the nut 2 is driven in translation by projecting into the space El and drives the braking pad P2 in translation towards the fixed braking pad PI to tighten the disc.

[0043] In the opposite direction to the rotational drive of the screw 1, the nut 2 is driven in translation backwards in the housing L, moving the movable plate P2 away from the fixed plate PI in the direction of loosening.

[0044] At the end of the nut 2 opening into the space El of the caliper E, a cap 9 is therefore mounted having a cylindrical skirt 9a engaged around the nut 2, the end of which, in the brake release position, is in abutment, preferably sealed, against the branch B2 at the periphery of the housing L. When the nut 2 is driven in translation in the direction of brake application, the skirt 9a of the cap 9 is no longer in abutment against the branch B2.

[0045] In order to preserve the sealing of the housing L, a sealing bellows 10 is fixed between the branch B2 of the caliper E and the cap 9. Thus when the nut 2 is actuated in the direction of application of the brake, the end of the nut 2 provided with the cap 9 fixed to the movable brake pad P2 drives the latter towards the fixed brake plate PI, the support of the skirt 9a of the cap against the branch B2 is broken and the sealing bellows 10 is stretched, thus maintaining the seal.

[0046] Preferably, the branch B2 has a rib 11 around the periphery of the housing L forming a shoulder 11a against which the end of the skirt 9a of the cap 9 is housed and which also allows the fixing of one end of the sealing bellows 10, the other end of which is fixed to the cap 9.

[0047] The cap 9 is mounted on the nut with a seal 12 interposed between said nut 2 and the skirt 9a of the cap 9.

[0048] At the other end of the housing L, the bore has a preferably larger diameter in which the means for transmitting the rotational movement of the motor pinion 5 to the screw 1 are housed, such as a planet carrier 6 and a crown 7. This crown 7 is therefore integral with both the planet carrier 6 and the screw 1. As can be seen in [Fig. 3], this crown 7 constitutes the end of the screw 1.

[0049] The through bore is made in the branch B2 of the caliper E to form the housing L opening into the space El between said branch B2 and the branch Bl. The screw / nut system is mounted in said housing, the end of the nut 2 is connected with the cap 9 and the brake pad P2, and the sealing bellows 10 is then put in place.

[0050] The means for transmitting the rotational movement are mounted at the end of the bore, the end of the screw 1 in the form of a crown 7 is connected to the planet carrier 6 which is engaged with the motor pinion 5, the latter then being connected to the motor shaft 4 of an electric motor M, mounted in a housing B fixed to the bracket E at the exit from housing L and closed using a protective cover C.

[0051] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention.

[0052] NOMENCLATURE F disc brake E stirrup Bl, B2 branch of the stapes The space between the branches of the stirrup PI fixed brake pad P2 movable brake pad The accommodation 1 screw 2 nuts 3 marbles 4 shaft motor 5 motor pinion 6 satellite carriers 7 crowns 8 satellite pinion 9 cap 9a hood skirt 10 sealing bellows 11 fixing rib the shoulder of the fixing rib 12 gasket M electric motor B electric motor housing C protective cover

Claims

Claims

1. Disc brake (F) comprising a caliper (E) comprising, opposite each other, a fixed brake pad (P1) and a movable brake pad (P2) relative to the caliper (E), as well as a mechanism for actuating the movable brake pad (P2) comprising a screw / nut system and means for transmitting a rotational movement of a drive shaft (4) to the screw / nut system to actuate the movable brake pad (P2), characterized in that the screw / nut system is mounted in a housing (L) provided in the caliper (E), the screw (1) of the screw-nut mechanism being mounted fixed in translation in said housing (L) and drivable in rotation by the transmission means, while the nut (2) mounted fixed in rotation in said housing (L) is drivable in translation along the screw (1) when the latter is driven in rotation,the translational drive of the nut (2) in a first direction allowing the movable brake pad (P2) to be driven in translation towards the fixed brake pad (PI) and the translational drive of the nut (2) in the opposite direction allowing the movable brake pad (P2) to be moved away from the fixed brake pad (PI).,

2. Disc brake (F) according to claim 1, characterized in that one (B2) of the branches (Bl, B2) of the caliper (E) comprises the housing (L) in which the screw-nut system is mounted, this cylindrical housing (L) with circular section, is open at one end in the space (El) between said branches (Bl, B2) and accommodates at its other end at least in part, the means for transmitting the rotation of the motor pinion (5) to the screw (1).

3. Disc brake (F) according to claim 1 or 2, characterized in that said housing (L) thus has at least one bore having dimensions complementary to the nut (2) of the screw-nut system, said bore comprising fixing means complementary to fixing means provided on the nut, allowing said nut (2) to be mounted fixed in rotation and movable in translation in the housing (L).

4. Disc brake (F) according to one of claims 1 to 3, characterized in that these fixing means comprise at least one axial rib extending on the external wall of the nut (2) along its longitudinal axis and an axial groove formed in correspondence in the wall of the housing (L), the axial rib of the nut (2) being engageable in the axial groove formed in the wall of the housing (L).

5. Disc brake (F) according to one of claims 1 to 4, characterized in that the means for transmitting a rotational movement from a motor pinion to the screw / nut system are also housed in said housing (L) and constituted, from the motor shaft (4), by a motor pinion (5), a planet carrier (6), and a crown (7), integral with both the planet carrier (6) and the screw (1) of the screw / nut system.

6. Disc brake (F) according to claim 5, characterized in that the crown (7) is made in one piece with the screw (1), such as constituting the end of the screw (1), the other end of which is engaged in the nut (2).

7. Disc brake (F) according to claim 6, characterized in that the screw / nut system consists of a ball screw / nut system.

8. Disc brake (F) according to one of claims 1 to 7, characterized in that the nut (2) is in the form of a cylindrical sleeve surrounding the screw (1), having a thread on its inner wall, engaged with that of the screw (1), and locked in rotation in the housing, said nut (2) being driven in translation under the effect of the rotational drive of the screw (1), the end of the nut (2) intended to project into the space (El) between the branches (Bl, B2) of the caliper (E), being in abutment against the brake pad (P2).

9. Disc brake (F) according to claim 8, characterized in that the nut (2) has at its end, mounted in a sealed manner, a cap (9).

10. Disc brake (F) according to claim 9, characterized in that a sealing bellows (10) is also fixed between the periphery of the housing (L) and the cap (9).

11. Disc brake (F) according to one of claims 9 and 10, characterized in that the screw-nut system, the cap (9) and the sealing bellows (10) are assembled in the form of a module insertable into the housing (L) provided in the caliper (E).

12. Motor vehicle equipped with disc brakes according to one of claims 1 to 11.

13. Method for manufacturing a disc brake (F) according to one of claims 1 to 11, comprising a caliper (E) comprising, facing each other, a fixed brake pad (PI) and a movable brake pad (P2) relative to the caliper, as well as a mechanism for actuating the movable brake pad (P2) comprising a screw / nut system and means for transmitting a rotational movement of a pinion motor (5) to the screw / nut system for actuating the movable brake pad (P2), characterized in that a through bore is made in one of the branches of the caliper (E) to form a housing (L) opening into the space (El) between the branches (Bl, B2), the screw / nut system is mounted in said housing (L), one end of the screw (1) is connected to the means for transmitting the rotational movement of a motor pinion (5) connected to an electric motor (M) while the end of the nut (2) is fixed to the movable brake pad (P2).

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