Disc brake system for a motor vehicle, having a brake mechanism with a reduced size

Abstract

A brake system includes a brake disc, rotary movable around a disc axis, and a brake mechanism. The brake mechanism includes a brake pad, movable in a first direction, a cylinder having a piston movable in a second direction, a lever rotary movable around a lever axis, the lever being connected to the piston, a cam element, arranged to convert a rotary motion of the lever around the lever axis, into a translation motion in the first direction, and a rod, expanding between the brake pad and the cam element. The lever, the cam element and the rod are housed in a housing. Considering a plane including the disc axis and the first direction, the lever axis is inclined relative to the plane, at an angle different from 90°.

Claims

1. A disc brake system for a wheel of a motor vehicle, comprising: a brake disc, rotary movable around a disc axis, intended to be rotary connected with the wheel, and a brake mechanism, comprising: at least one brake pad having a central pad axis that is parallel to the disc axis and that defines a first direction according to which the brake pad can move between a first position away from the brake disc, and a second position in contact with the brake disc, a pneumatic cylinder, a lever, rotary movable around a lever axis, the lever having a lever end that can be driven in rotation around the lever axis, a cam element, arranged to convert a rotary motion of the lever around the lever axis, into a translation motion in the first direction, at least one piston, expanding between a first end connected to the brake pad and a second end connected to the cam element, so as to transmit a translation motion in the first direction from the cam element to the brake pad, and a housing, at least for to lever, the cam element and the piston, wherein, considering a plane defined by the disc axis and the central pad axis, the lever axis is inclined relative to the plane, at an angle different from 90°, wherein the lever is inclined at an angle between 0 and 45° with respect to a direction that is perpendicular to the lever axis.

2. The disc brake system according to claim 1, wherein the lever axis is inclined relative to the plane at an angle between −35° and 55°.

3. The disc brake system according to claim 2, wherein the lever axis is inclined relative to the plane at an angle between 10 and 55° such that the end of the lever opposite to the lever axis is located in the half part of the housing that is furthest from the disc axis.

4. The disc brake system according to claim 3, wherein the lever axis is inclined relative to the plane at an angle of 30°.

5. The disc brake system according to claim 1, wherein the lever expands in a direction that is perpendicular to the lever axis.

6. The disc brake system according to claim 1, wherein the plane is vertical.

7. The disc brake system according to claim 1, wherein: the cam element is a cylinder having an outer surface comprising at least a rounded part around a cam axis, the cam axis is parallel to the lever axis and it is different from this lever axis, the cam element is rotary movable around the lever axis, and the second end of the piston is arranged in contact with the rounded part of the cam element.

8. The disc brake system according to claim 7, wherein the lever is integral with the cam element.

9. The disc brake system according to claim 1, comprising an adjuster, for compensating a reduction in the thickness of the brake pad in the first direction, the adjuster being housed in the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following detailed description of several embodiments of the invention is better understood when read in conjunction with the appended drawings, it being however understood that the invention is not limited to the specific embodiments disclosed.

(2) FIG. 1 is a perspective view of a partially shown disc brake system according to a first example of embodiment of the invention, arranged in a wheel of a motor vehicle;

(3) FIG. 2 is a front view of a disc brake system according to an aspect of the present invention;

(4) FIG. 3 is an axial profile of the disc brake system of FIG. 1;

(5) FIG. 4 is a perspective view of a lever of force transmission means of the disc brake system of FIG. 1;

(6) FIG. 5 is a perspective view of a disc brake system according to a second example of embodiment of the invention;

(7) FIGS. 6.a and 6.b are front views representing the lever of FIG. 2 in two extreme angular positions according to a preferred embodiment;

(8) FIGS. 7.a and 7.b are front views representing the lever of FIG. 2 in two extreme angular positions according to another preferred embodiment.

DETAILED DESCRIPTION

(9) With reference to FIG. 1 to 3, we describe a disc brake system 10 intended to be arranged on a wheel 12 of a motor vehicle. It will be appreciated that FIG. 2 is not necessarily consistent in all ways with FIGS. 1 and 3.

(10) The wheel 12 is standard, and it comprises a rim 14 having a revolution form around a wheel axis Xw. The wheel 12 also comprises a tire 16, arranged on the rim 14, coaxially to this rim 14. When the axle 43 is a driving axle, the wheel 12 is mounted on the drive shaft 17 expanding along the wheel axis Xw. To this end, a part 14A of the rim 14 is fastened to the drive shaft 17. It is noticed that the disc brake system 10 according to the invention can also be mounted on an axle that is also a steering axle or that is not a driving axle, for instance, a steering axle where the wheel is connected to the steering axle via a knuckle not represented).

(11) The disc brake system 10 comprises a brake disc 18, rotary fastened to the wheel 12 or to the drive shaft 17 when it is considered a driving axle.

(12) It should be noticed that the brake disc 18 has an annular shape around a disc axis. In particular, the brake disc 18 radially expands between an inner edge 18A and an outer edge 18B. The disc axis is merged with the wheel axis Xw, so it will be also referred Xw.

(13) Besides, the disc brake system 10 comprises a brake mechanism 19, intended to cooperate with the brake disc 18. In particular, the disc brake system 10 comprises at least one brake pad 20 having a central pad axis XP that is parallel to the disc axis (Xw) and that defines a first direction D1 according to which the brake pad can move between a first position away from the brake disc 18, and a second position in contact with the brake disc 18.

(14) The brake mechanism 19 generally comprises another brake pad 22, arranged on the other side of the brake disc 18. When the brake mechanism is equipped with two opposite brake pads 20, 22, the brake pads 20, 22 are mounted on a calliper, so that, when the brake pad 20 is in its second position, the brake disc 18 is pinched between the brake pad 20 and the other brake pad 22. It should be noticed that each brake pad 20, 22 is rotary motionless. Thus, the brake disc 18 in rotation is slowed down when pinched between the brake pads 20, 22.

(15) As usual, each brake pad 20, 22 is provided with a friction lining for a friction against the brake disc 18 when pinched. Because of wear, the thickness of the friction lining is reduced during his life time. Thus, the brake mechanism 19 comprises an adjuster (not shown) for compensating a reduction in the thickness of this friction lining.

(16) Besides, the brake mechanism 19 comprises a cylinder 24, in particular a pneumatic cylinder, having a rod movable in a second direction D2, parallel or substantially parallel to the first direction D1. This rod is intended to provide a pushing force that is intended to be transmitted to the brake pad 20 through force transmission means 26.

(17) The force transmission means 26 comprise a lever 28, rotary movable around a lever axis XL. In this first embodiment, the lever 28 expands in a direction that is perpendicular to the lever axis XL.

(18) The lever 28 is connected to said rod via its lever end 40, so as to be driven in rotation around the lever axis XL when the rod is moved in the second direction D2.

(19) The force transmission means 26 also comprise a cam element 30, arranged to convert a rotary motion of the lever 28 around the lever axis XL, into a translation motion in the first direction D1. Thus, the cam element 30 is rotary connected to the lever 28 around the lever axis XL.

(20) An example of cam element 30 is more precisely shown on FIG. 4. As shown on this FIG. 4, the cam element 30 is a cylinder having an outer surface comprising at least a rounded part 32 around a cam axis Xc. This cam axis Xc is parallel to the lever axis XL, and it is different from this lever axis XL. Besides, the cam element 30 is rotary movable around the lever axis XL. Thus, this cam element 30 forms an eccentric shape regarding the lever axis XL, so that the position of the cam element 30 in the first direction D1 changes when it turns around the lever axis XL.

(21) Preferably, the lever 28 is integral with the cam element 30.

(22) The brake mechanism 19 also comprises a piston 34, expanding in the first direction D1 between a first end 34A connected to the brake pad 20 and a second end 34B connected to the cam element 30, so as to transmit a translation motion in the first direction D1 from the cam element 30 to the brake pad 20. More particularly, the second end 34B of the piston 34 is arranged in contact with the rounded part 32 of the can element 30. In order to have an optimized efficiency, the piston 34 is directed toward a central line between the inner edge 18A and the outer edge 18B of the brake disc 18. The brake mechanism 19 may also comprises two pistons instead of one.

(23) When the brake mechanism comprises only one piston 34, the central pad axis XP is preferably merged with the main axis of the piston 34 such as depicted on FIGS. 1, 2 and 3.

(24) It should be noticed that the disc brake system 10 comprises a housing 36, shown on FIGS. 2, 3 and 5, at least for housing the force transmission means 26 (i.e. the lever 28, the cam element 30 and the piston 34), and may also comprise the adjuster. For the sake of clarity the housing is not represented on FIGS. 1 and 4.

(25) The housing 36 can be delimited by at least a first wall 37 that is radially further from the disc axis Xw and a second wall 38 of the housing that is radially closer to the disc axis Xw.

(26) The cylinder 24 is preferably fastened to this housing 36, with a seal arranged between this cylinder 24 and this housing 36.

(27) In the following disclosure, we consider a plane P, comprising the disc axis Xw and the central pad axis XP. This plane P is shown on FIG. 2, and this plane P is the cut plane in which FIG. 3 is drawn, however, it will be appreciated that FIG. 2 is not necessarily consistent in all ways with FIGS. 1 and 3. In the disclosed example, the plane P vertical but is could also be oriented in any other direction, for instance, horizontally depending on the global orientation of the the disc brake system 10 around the wheel axis Xw.

(28) When the brake mechanism comprises only one piston 34, the plane P can also be defined as a plane comprising the disc axis Xw and the the main axis of the piston 34.

(29) The lever axis XL is inclined relative to said plane P, at an angle a different from 90°. In other words, when the disc brake system 10 is arranged above the wheel axis Xw, the lever 28 expands in a direction that is not vertical.

(30) Thus, comparing with a disc brake system from prior art, wherein the lever expands in a vertical direction, the lever stroke in the invention is lowered in the vertical direction. So, the housing 36 can still comprise a boss or a specific volume extending radially and outwardly away from the disc axis Xw, in order to allow the lever stroke, but thanks to the invention it is reduced with regard to a boss or specific volume of a housing from prior art.

(31) Indeed, referring to FIG. 3, it can be seen that a usual rim 14 comprises a part 14B with a lower diameter. Because of this part 14B, the lever of a disc brake system from the prior art has to be deported in the first direction, because said boss or specific housing of the housing would be in a radial conflict with this part 14B.

(32) In FIGS. 2 and 3, for the sake of clarity, the hatched zone 42 represents a global volume occupied by the shaft, the hub that is connected to the wheel and the axle when the disc brake mechanism is for instance mounted on a drive axle.

(33) Since the invention allows reducing, or suppressing, the boss or the specific volume, it is possible to arrange the lever 28 under the part 14B of the rim 14, as shown in FIG. 3, instead of deporting it in the first direction D1.

(34) Preferentially and such as represented in FIGS. 6.a and 6b, the angle is between −35° and 55°. Indeed, if the angles is superior to 55°, said boss in the housing 36 is considered as not sufficiently reduced. Beside, if the angle is inferior to −35°, the cylinder 24, that is arranged aligned with the lever 28 in the second direction D2, may be in conflict with other components that are disposed around the brake system 10.

(35) More preferably and such as represented in FIGS. 7.a and 7.b, the angle is comprised between 10° and 55°. In this range of valies the lever end 40 is located in the half part 41 of the housing 36 that is furthest from the disc axis Xw (FIGS. 2 and 5).

(36) To be more precise “the half part of the housing that is furthest from the disc axis” refers to the inside part 41 of the housing that extends between the first wall 37 and a median line 39 that extends between the first wall 37 and the second wall 38 and having, for instance, the form of an arc of circle centred on the disc axis Xw. Thanks to that, the location of the cylinder 24 has a low impact on the accessibility of the different fastening means of the disc brake system 10. For instance, screw and bolt assemblies (not represented) used to secure the brake mechanism 19 on the axle 43 or on a knuckle of the vehicle are therefore easy to access, so that the brake mechanism 19 can be easily assembled or disassembled from the axle 43 or from a knuckle when it is considered a steering axle.

(37) It should be noticed that an optimal angle a is equal to 30°. Indeed, as shown on FIG. 2, the housing 36 does not need a boss for housing the lever stroke if the angle <<=30°. More particularly, the size of the brake mechanism 19 is optimized for such an angle <<=30°.

(38) A second embodiment of the invention is now disclosed in reference to FIG. 5. On this FIG. 5, elements similar to those previously disclosed have a same reference.

(39) According to this second embodiment, the lever axis XL is inclined relative to the plan P at an angle about 50° and the lever 28 extends in a direction that is not perpendicular to the lever axis XL. To be more precise the lever 28 is inclined at an angle β that is about 25° with respect to a direction that is perpendicular to the lever axis XL Thus, it is possible to reduce the size of the housing 36 by inclining the lever 28 with regards to a direction perpendicular to the lever axis XL. To reduce the size of the housing 36 and according to the invention, different angles can be considered so that, when the lever axis XL is inclined relative to said plane P at an angle different from 90° and preferably comprised between −35° and 55°, the angle β can be comprised between 0 and 45° with respect to a direction titans perpendicular to the lever axis XL.

(40) It should be noticed that the invention is not limited to the previously disclosed embodiments, but it can contain additional features or variants.