FR2788572A1 - Disk brake for automobiles has rigid annular piston with annular wall which forms chamber for fluid with brake pad housing and seals - Google Patents

Abstract

The disk brake is operated hydraulically by a rigid annular piston (7) which forms an annular chamber with the brake pad housing (6). Brake fluid is fed into this under pressure by the brake control. The piston is arranged opposite the circumference of the brake disk (4) and moves the mobile brake pad (61) when the brakes are applied. The piston has an annular wall (70) at the back of the mobile brake pad which forms the fluid chamber (72) with the brake pad housing and sealing devices

Description

The present invention relates to a braking device of the brake type

  disc, especially for a motor vehicle. Conventionally, such a braking device comprises a disc secured to the wheel and rotating with it, two brake pads made of friction material secured to the fixed structure of the vehicle and arranged opposite a sector of the disc. , for example between 40 and 60 degrees, as well as means for clamping the two pads against the disc, under the control of a brake pedal, in order to generate braking torque. These means are, for example, constituted by a substantially cylindrical piston which can slide in the housing of the brake pads. In general, the housing is axially floating, while the brake disc

is fixed radially and axially.

  If the braking device has brake pads distributed in several sectors, the

  clamping means also include several pistons.

  Document WO-A-98/29671 describes a braking device of the disc brake type, in which the disc is fixed on the wheel hub while being able to move axially, the two brake pads being placed in a housing integral with the wheel support and having an annular shape. They are therefore opposite

of the entire periphery of the disc.

  Furthermore, the means for clamping the two plates against the disc are here constituted by an annular membrane situated between the housing of the

platelets and one of the platelets.

  When the brake pedal is actuated, fluid penetrates the diaphragm which expands, which causes the axial displacement of the pad adjacent to the diaphragm, which comes against the disc. The latter itself moves axially against the other plate linked to the housing. A braking torque is thus generated. Insofar as contact between the disc and the brake pads is established over the entire periphery of the disc, the

  clamping forces are distributed uniformly.

  However, the expandable annular membrane is repeatedly stressed and is subjected to significant stresses. There are therefore risks of deterioration of the membrane, deterioration which has

  disastrous security consequences.

  The invention aims to overcome these drawbacks by proposing a braking device of the disc brake type, in which the means for clamping the pads against the disc are common to all the pads, whether they are distributed in one or more sectors. or even annular, which simplifies their manufacture, and in which these same clamping means are of the rigid piston type, the operation of which is

  safer than an expandable membrane.

  Thus, the invention relates to a braking device of the disc brake type for a vehicle wheel rotatably mounted on a wheel support, comprising: - a brake disc integral in rotation with said wheel, - at least two brake pads arranged in an annular housing integral with the wheel support, and on either side of at least part of the periphery of said brake disc, one of the pads being fixed relative to said housing while the other is axially movable, and - a device for clamping said pads against said disc, hydraulically controlled and disposed in said pad housing, characterized in that said clamping device comprises a rigid annular piston defining with said pad housing, in which it is mounted in axial sliding , a fluid chamber also annular and supplied with pressurized fluid under the action of braking control means, said piston being disposed vis-a-vis is around the brake disc and directly exerting a clamping force on said axially movable pad, when the means of

control are activated.

  Preferably, the piston has a radial annular wall opposite said axially movable plate, this radial wall defining said annular fluid chamber with said housing.

  pads and sealing means.

  In a first embodiment, this radial annular wall constitutes the inner radial face of the piston. In a second embodiment, the piston has an annular groove opening onto its inner radial face, the bottom of this groove constituting said radial annular wall, set back from

said inner radial face.

  The platelet housing advantageously comprises a recess in the form of an annular groove, in

  which said piston is mounted in axial sliding.

  In the first embodiment, the fluid chamber is defined by the inner radial face of the

  piston and said annular groove of the housing.

  In the second embodiment, said groove of the platelet housing comprises, at its bottom, a projecting annular element, the fluid chamber then being defined by said projecting element and said

annular groove of the piston.

  Preferably, the sealing means consist of two coaxial annular seals which are offset radially. These annular seals are advantageously mounted in grooves provided in the piston, in the housing

  pads or in the piston and the housing.

  Furthermore, the piston is advantageously

  secured to the support of the axially movable plate.

  Preferably, the braking device according to the invention comprises two annular brake pads

  in contact with the entire periphery of said brake disc.

  The invention will be better understood and other objects, advantages and characteristics thereof will appear

  more clearly on reading the description which follows

  and which is made with reference to the appended drawings which represent nonlimiting examples of embodiment of the invention and in which: FIG. 1 is an axial half-section of an example of a braking device according to the invention, mounted on a vehicle; FIG. 2 is a half-view in section along II-II of FIG. 1;

  FIG. 3 is a half-view in section on III-

  III of Figure 1; - Figure 4 is a detail of Figure 1, illustrating an alternative embodiment; - Figure 5 is a perspective half-view of the piston of the braking device according to Figures 1 to 4; - Figure 6 is a partial half-view in axial section of another embodiment of the braking device according to the invention;

  - Figure 7 is a half sectional view along VII-

  VII of Figure 6; - Figure 8 is a perspective half-view of the piston of the braking device according to Figures 6 and 7; and - Figure 9 illustrates a detail of Figure 6

  representing an alternative embodiment.

  The elements common to the different figures will be

  designated by the same references.

  Firstly, reference is made to FIG. 1, in which the reference 1 designates the hub of a vehicle wheel, in particular a motor vehicle (wheel not shown), the axis of which is identified at 10, the reference 2 designates a bearing and reference 3, a wheel support, commonly designated by pivot as well for the wheels

front than for the rear wheels.

  The braking device according to the invention comprises a brake disc 4 which is connected to the hub 1 by a

disc holder 5.

  The connection between the disc support 5 and the disc 4 is such that the disc is integral in rotation with the wheel but can move axially relative to the

  wheel, hub 1 and wheel support 3.

  This is illustrated in particular in Figure 2.

  In this exemplary embodiment, the outer surface 50 of the disc support 5 has projections 51 which are housed in corresponding recesses 41 which are provided on the inner surface 40 of the brake disc 4. Thanks to this connection, the disc support 5 and the brake disc 4 are well connected in rotation, but the disc 4 can move axially relative to the disc support 5,

to the hub 1 and to the wheel support 3.

  The invention is of course not limited to this mode of

  connection between the brake disc 4 and the wheel.

  The braking device also includes a housing 6 for two brake pads 60 and 61, the

  housing 6 being integral with the wheel support 3.

  These plates 60 and 61 are conventionally produced

made of friction material.

  Slot 6 for pads is annular and centered

on the axis 10 of the hub 1.

  In the example illustrated in the figures, the

  plates 60 and 61 are also annular in shape.

  However, the invention is not limited to this embodiment. The plates could be distributed according to one or more sectors, in particular between

40 and 60 degrees.

  Conventionally, the two pads are arranged on either side of at least part of the periphery of the brake disc, here the entire periphery

  since the pads are annular.

  In the illustrated embodiment, the outer plate 60 is secured to the housing 6 by means of its support 62, this plate 60

  being fixed relative to the housing 6.

  The inner plate 61 is also integral with the housing 6 but can move axially with respect to said housing, along the axis 10 of the hub 1. The mounting 63 of the plate 61 in the housing 6 is carried out in an appropriate manner. This support may in particular have projections sliding in grooves provided in the housing 6. These particular mounting means are not illustrated on the

figures.

  We can also refer to Figure 2 which illustrates

  the plate 61 with the support 63 in the housing 6.

  The braking device according to the invention also comprises a device for clamping the pads which

  comprises a rigid piston 7 of annular shape.

  This piston 7 is also illustrated in FIG. 5.

  In the example illustrated by the figures, this piston is integral with the support 63 of the wafer 61, the piston

  and the support being made in one piece.

  As illustrated in FIG. 1, the piston 7 is arranged opposite the internal periphery of the brake disc 4, it is therefore intended to directly apply a

  clamping force on the inner plate 61.

  In the example illustrated in Figures 1 to 5, this piston 7 has a radial annular wall 70, opposite to

  the inner plate 61 which is axially movable.

  This radial wall 70 here constitutes the radial face

inside of the piston.

  The plate housing 6 defines a recess 64 in the form of an annular groove, in which the piston is mounted in axial sliding, the piston 7 being able to move along the axis 10 of the hub 1. The piston

7 is therefore of the "male" type.

  Thus, the inner radial face 70 of the piston 7 and the annular groove 64 of the housing 6 define a fluid chamber 72. This chamber is supplied with fluid under pressure via a conduit 73 passing through the housing 6, this conduit 73 being in communication with a hydraulic circuit actuated by control means

  brakes, such as a brake pedal (not shown).

  The sealing of this fluid chamber 72 is ensured by two annular seals 74, 75 which are arranged in annular grooves 65, 66, formed in

housing 6.

  We can also refer to Figure 3 which illustrates the piston 7 between the two annular seals 74

and 75.

  The annular seals 74 and 75 both have for axis the axis 10 of the hub 1, but they are offset radially to frame the piston 7. It is not

  the joints must be offset axially.

  The operation of the braking device according to

the invention is as follows.

  When pressurized fluid enters the fluid chamber 72, in particular under the action of a brake pedal, the assembly constituted by the piston 7 and the internal plate 61 moves axially towards the

brake disc 4.

  The inner plate 61 thus comes into contact with the disc 4 which itself moves axially to

  come into contact with the outer plate 60.

  The clamping forces on the disc 4 generate a

braking torque for the wheel.

  Thus, whatever the distribution of the brake pads, annular or in one or more sectors, a single clamping device is necessary to generate a braking torque. This simplifies the

  manufacturing and reduce costs.

  Furthermore, the single rigid annular piston ensures a uniform distribution of the pressure and therefore of the clamping forces over the entire periphery of the brake disc. We now refer to Figure 4 which illustrates an alternative embodiment of the braking device

illustrated in Figures 1, 2, 3 and 5.

  In this alternative embodiment, the annular seals 74 and 75 are not arranged in annular grooves made in the housing 6, but in

  annular grooves 74a and 75a produced in the piston 7.

  One could also provide for having an annular seal in an annular groove provided in the piston 7 and another annular seal in an annular groove provided in the housing 6 (this variant embodiment

  is not illustrated in the figures).

  We now refer to Figures 6 to 8 which illustrate another embodiment of the device

braking according to the invention.

  In this exemplary embodiment, the piston 8 always includes a radial annular wall 80, at

  the opposite of the movable plate 61.

  However, in this example, this radial annular wall 80 is constituted by the bottom of an annular groove 86 which opens onto the inner radial face 87 of the piston. Thus, unlike the embodiment illustrated in the preceding figures, the radial annular wall 80 is set back relative to the face

inner radial piston.

  The housing 6 also has a recess 64 in the form of an annular groove, in which the piston

8 is mounted in axial sliding.

  This recess 64 has at its bottom an annular element 67 projecting which is intended to be inserted in

  the annular groove 86 of the piston 8.

  In this exemplary embodiment, the fluid chamber 82 is defined by the projecting annular element

  67 of the housing 6 and the annular groove 86 of the piston 8.

  The piston 8 is therefore of the "female" type.

  The chamber 82 is supplied with pressurized fluid via the conduit 83 passing through the housing 6, this conduit 83 being in communication with a hydraulic circuit actuated by control means of

braking (not shown).

  The tightness of this chamber 82 is ensured by two annular seals 84 and 85 which are housed in annular grooves 84a and 85a produced in the piston 8,

  and which open into the annular groove 86 of the piston.

  Reference may also be made to FIG. 7 which illustrates the projecting annular element 67 between the two annular seals 84 and 85, as well as the piston 8 in

  the annular recess 64 of the housing 6.

  The annular seals 84 and 85 are coaxial, but they are offset radially relative to the axis 10 of the hub 1 to frame the protruding element 67. It is not

  the joints need not be offset axially.

  FIG. 9 illustrates an alternative embodiment of the braking device according to FIGS. 6 to 8, in which the annular seals 84 and 85 ensuring the tightness of the fluid chamber 82 are provided in annular grooves 68 and 69 produced in the housing 6. As indicated previously, an annular seal could also be provided in the piston 8 and another

annular seal in the housing 6.

  The operation of the braking device illustrated in Figures 6 to 9 is identical to that previously described for the braking device

illustrated in Figures 1 to 5.

  It is understood that the invention is not limited to the embodiments described and shown. In particular, if in what has been described, the disc is floating and the fixed wafer housing, the invention applies equally well in the case of a fixed disc and a floating housing. The reference signs inserted after the

  technical features included in the claims are intended only to facilitate the

  understanding of these and cannot limit their scope.

Claims (11)

CLAIMS R E V E N D I C A T LQ - N   1. A brake device of the disc brake type for a vehicle wheel rotatably mounted on a wheel support, comprising: - a brake disc (4) integral in rotation with said wheel, - at least two brake pads (60 , 61) arranged in an annular housing (6) integral with the wheel support (3), and on either side of at least part of the periphery of said brake disc (4), one of the pads (60) being fixed relative to said housing (6) while the other (61) is axially movable, and - a device for clamping said pads against said brake disc (4), hydraulically controlled and disposed in said pad housing (6) , characterized in that said clamping device comprises a rigid annular piston (7, 8) defining with said insert housing (6), in which it is mounted in axial sliding, a fluid chamber (72, 82) also annular and supplied with pressurized fluid under the action of control means of fr einage, said piston (7, 8) being disposed opposite the periphery of the brake disc (4) and directly exerting a clamping force on said pad (61) movable axially, when the control means are operated.   2. Braking device according to claim 1, characterized in that said piston (7, 8) comprises a radial annular wall (70, 80), opposite said axially movable plate (61), this radial wall defining said annular fluid chamber (72, 82) with said platelet housing (6) and sealing means. 3. Braking device according to claim 2, characterized in that said radial annular wall (70)   constitutes the inner radial face of the piston (7).   4. Braking device according to claim 2, characterized in that said piston (8) has an annular groove (86) opening onto its inner radial face (87), the bottom of the groove constituting said radial annular wall (80), set back from   said inner radial face (87).   5. Braking device according to claim 3 or 4, characterized in that the pad housing (6) has a recess in the form of an annular groove (64), in which said piston (7, 8) is mounted in axial sliding.   6. Braking device according to claims   3 and 5, characterized in that said fluid chamber (72) is defined by the inner radial face (70) of the piston (7) and said annular groove (64) of the housing (6).   7. Braking device according to claims   4 and 5, characterized in that said annular groove (64) of the housing (6) has in its bottom an annular element (67) projecting, the fluid chamber (82) being defined by said projecting element (67) and said   annular groove (86) of the piston (8).   8. Braking device according to one of   claims 2 to 7, characterized in that the means   sealing consist of two annular seals   (74, 75; 84, 85), coaxial and offset radially.   9. Braking device according to claim 8, characterized in that said annular seals (74, 75; 84, 85) are mounted in grooves (74a, 75a; 84a, 85a) provided in the piston (7, 8), in grooves (65, 66; 68, 69) provided in the housing (6) or even grooves   provided in the piston and the housing.   10. Device according to one of claims 1 to   9, characterized in that said piston (7, 8) is integral with the support (63) of the movable plate (61)   axially. 11. Braking device according to one of claims 1 to 10, characterized in that it comprises   two annular brake pads in contact with the entire periphery of said brake disc.