FR2788573A1 - Disk brake for automobiles has rigid annular piston slidably mounted in wheel support and forming annular fluid chamber with it - Google Patents

Abstract

The disk brake is operated hydraulically by a rigid annular piston (7) which is mounted so that it can slide axially within the wheel support (3), near its axis of rotation (10). The piston forms an annular fluid chamber (72) with the wheel support which is fed with fluid under pressure by the brake control. The piston is moved towards the axis of rotation of the wheel with respect to the circumference of the brake disk (4) and indirectly applies force to the mobile disk pad (61) when the brakes are applied.

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 plates against said disc, hydraulically controlled, characterized in that said clamping device comprises a rigid annular piston mounted in axial sliding in said wheel support, near the axis of rotation of the wheel, this piston defining with said wheel support a fluid chamber also annular and supplied with fluid under pressure under the action of braking control means, the piston being offset towards s the axis of rotation of the wheel with respect to the periphery of the brake disc and indirectly exerting a clamping force on said axially movable pad, when

  said control means are actuated.

  Preferably, the piston has a radial annular wall which defines said annular fluid chamber with said wheel support and sealing means, means for connection with said axially movable plate being fixed on the piston, opposite

of said radial wall.

  These connecting means are advantageously secured to the support of said movable plate.

axially and from said piston.

  Preferably, the wheel support has a recess having an annular groove, in which

  said piston is mounted in axial sliding.

  In a first embodiment, said 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 the groove constituting said radial annular wall, set back from

said inner radial face.

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

  of the piston and said annular groove of the wheel support.

  In the second embodiment, said recess of the wheel support comprises a projecting annular element, the fluid chamber then being defined by said projecting element and said groove

piston annular.

  The sealing means are advantageously constituted by two coaxial and offset annular seals

radially.

  These annular seals can be mounted in grooves provided in the piston, in the wheel support or

  still in the piston and the wheel holder.

  The braking device according to the invention advantageously comprises two annular brake pads, in contact with the entire periphery of said disc

of brake.

  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; - Figure 2 is a half sectional view along II-II of Figure 1;

  - Figure 3 is a half-sectional view along III-

  III of Figure 1; - Figure 4 is a detail of Figure 1, illustrating an alternative embodiment; - Figure 5 is a half perspective view of the piston of the braking device according to Figures 1 to 4, associated with a brake pad; - 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 half perspective view of the piston of the braking device according to Figures 6 and 7, associated with a brake pad; - Figure 9 illustrates a first alternative embodiment of Figure 6; and - Figure 10 is a view similar to Figure 9

  representing a second 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 rotation of which is marked at 10, the reference 2 designates a bearing and reference 3, a wheel support, commonly designated by pivot as well for

  front wheels only for 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 by

  relative to the wheel, to the hub 1 and to the 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 recesses 41,

  provided on the inner surface 40 of the brake disc 4.

  With 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 holder 5, hub 1 and wheel holder 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

  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 also be distributed according to one or more sectors, in particular

between 40 and 60 degrees.

  Conventionally, the two pads 60 and 61 are arranged on either side of at least part of the periphery of the brake disc, here the entire

  around since the plates 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.

  One can also refer to FIG. 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.

  The piston 7 is disposed near the axis of rotation 10 of the wheel and therefore has a central position. It is not disposed facing the periphery of the brake disc 4 since it is offset towards the axis of rotation of the wheel with respect to this periphery. Thus, it is intended to indirectly apply a force of

  tightening on the inner plate 61.

  This clamping force is transmitted to the inner plate 61 by means of connection means 9,

annular in shape.

  In the embodiment illustrated in the figures, the piston 7, the connecting means 9 and the support 63 of the wafer 61 are produced in a single

  part, for example in sheet metal or aluminum foundry.

  However, the invention is not limited to this embodiment. In the example illustrated in Figures 1 to 5, this piston 7 has a radial annular wall 70, opposite the outer face 76 of the piston 7 which is connected to the connecting means 9. This radial wall 70

  here constitutes the inner radial face of the piston.

  The wheel support 3 defines a recess 30 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 of rotation 10. The piston 7 is therefore

of the "male" type.

  Thus, the inner radial face 70 of the piston 7 and the annular groove 30 of the wheel support 3 define

a fluid chamber 72.

  This chamber 72 is supplied with pressurized fluid via a conduit 73 passing through the wheel support 3, this conduit 73 being in communication with a hydraulic circuit actuated by braking control means, such as a foot pedal.

brake (not shown).

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

in piston 7.

  Reference can be made to FIG. 3 which illustrates the piston 7 between the two annular seals 74 and 75, as well as the connecting means 9 between the piston and the

  inner plate 61, and also the housing 6.

  The annular seals 74 and 75 have both for axis, the axis 10 of the hub 1, but they are offset radially to frame the piston 7. It is not however necessary that the seals are offset axially to ensure the tightness of chamber 72. 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, the connecting means 9 and the internal plate 61 becomes

  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, in one or more sectors or even annular, a single clamping device is necessary to generate a braking torque. This simplifies manufacturing and reduces 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.

  In addition, the central position of the piston 7, that is to say

  say near the axis of rotation of the wheel, accommodates the piston 7 in the wheel support and not in the brake pad housing. This makes it possible to reduce the dimensions of the insert housing 6 and

  therefore to design a more compact braking device.

  Finally, the piston 7 being offset towards the axis of rotation of the wheel relative to the periphery of the brake disc, the hydraulic part of the braking device is distant from the brake pads where significant heating occurs. This central position of the piston 7 therefore makes it possible to limit the risks of overheating and vaporization of the fluid which is present in the chamber 72. Reference is now made to FIG. 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 piston 7, but in annular grooves 31 and 32 produced in the support

wheel 3.

  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 wheel support 3 (this variant of

  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 other embodiment, the piston 8 is always connected to the internal plate 61 by means of connection means 9. As in the preceding figures, the piston 8, the connection means 9 and the support 63 of the plate 61 are made in one

single piece.

  The piston 8 also includes a radial annular wall 80 opposite the external radial face 88 of the

  piston which is connected to the connecting means 9.

  This annular wall 80 is here constituted by the bottom of a groove 81 which opens onto the inner radial face 86 of the piston 8. Thus, unlike the embodiment illustrated in the previous figures, the radial annular wall 80 is set back

  relative to the inner radial face 86 of the piston.

  The wheel support 3 also has a recess 36, in which the piston 8 is mounted in axial sliding. In this recess 36 is provided a projecting annular element 37 which is intended to be inserted in

  the annular groove 81 of the piston 8.

  Thus, the recess 36 further defines an annular groove 33, in which the piston 8 is mounted in

axial sliding.

  In this exemplary embodiment, the fluid chamber 82 is defined by the projecting annular element 37 of the wheel support 3 and the annular groove 81 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 wheel support 3, this conduit 83 being in communication with a hydraulic circuit actuated by control means

brake (not shown).

  The tightness of the chamber 82 is ensured by two annular seals 84 and 85 which are housed in annular grooves 34 and 35 produced in the wheel support 3,

  and more precisely in the projecting element 37.

  Reference may also be made to FIG. 7 which illustrates the projecting element 37 of the wheel support 3, between the two annular seals 84 and 85, this projecting element 37 being housed in the annular groove 81 of the

piston 8.

  The annular seals 84 and 85 are coaxial, but they are offset radially relative to the axis 10 of the hub to frame the protruding element 37. It is not

  the joints must 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 84a and 85a produced in the piston 1i 8, these grooves 84a and 85a opening into the groove 81 of the piston. FIG. 10 illustrates yet another alternative embodiment of the braking device according to FIGS. 6 to 8, in which the annular seals 84 and 85 are still provided in annular grooves produced in the piston 8. However, one of the annular grooves 84a opens out in groove 81, while groove 85b

  opens onto the internal axial face 87 of the piston 8.

  As indicated previously, an annular seal could also be provided in the piston 8 and another

  ring seal in the wheel holder 3.

  The operation of the braking device illustrated in FIGS. 6 to 10 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 insert housing, one could also consider having the fixed disc and

floating housing.

  The reference signs inserted after the technical characteristics appearing in the

  claims are intended only to facilitate the

  understanding of these and cannot limit them

the scope.

Claims (11)

  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 arranged in a 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 plates against said disc, hydraulically controlled, characterized in that said clamping device comprises a rigid annular piston (7, 8) mounted in axial sliding in said wheel support (3), near the axis of rotation (10) of the wheel, this piston defining with said wheel support a fluid chamber (72, 82) also annular and supplied with fluid under pressure under the action of braking control means, the piston (7, 8) being offset towards the axis of rotation of the wheel relative to the periphery of the brake disc and indirectly exerting a clamping force on said pad (61) movable axially, when said control means are actuated.   2. Braking device according to claim 1, characterized in that said piston (7, 8) has a radial annular wall (70, 80) which defines said annular fluid chamber (72, 82) with said wheel support (3 ) and sealing means, connection means (9) with said axially movable plate (61) being fixed on the piston (7, 8), opposite said radial wall.   3. Braking device according to claim 2, characterized in that said connecting means (9) are integral with the support (63) of said movable pad   axially (61) and said piston (7, 8).   4. Braking device according to one of   Claims 1 to 3, characterized in that said support   wheel (3) has a recess (30, 36) having an annular groove (30, 33), in which said piston   (7, 8) is mounted in axial sliding.   5. Braking device according to one of   claims 2 to 4, characterized in that said wall   radial annular (70) constitutes the radial face inside of the piston (7).   6. Braking device according to one of   claims 2 to 4, characterized in that said piston   (8) has an annular groove (81) opening onto its inner radial face (86), the bottom of the groove constituting said annular wall (80), set back by   relative to said inner radial face (86).   7. Braking device according to claim 5, characterized in that the fluid chamber (72) is defined by the inner radial face (70) of the piston (7)   and said annular groove (30) of the wheel support (3).   8. Braking device according to claim 6, characterized in that said recess (36) of the wheel support (3) comprises a projecting annular element (37), the fluid chamber (82) then being defined by said element in projection (37) and said annular groove (81) piston (8).   9. Braking device according to one of   claims 2 to 8, characterized in that said   sealing means consist of two annular seals (74, 75; 84, 85) coaxial and offset radially. 10. Braking device according to claim 9, characterized in that said annular seals (74,; 84, 85) can be mounted in grooves (74a, a; 84a, 85a, 85b) provided in the piston (7, 8 ), in grooves (31, 32; 34, 35) provided in the support of   wheel (3) or grooves provided in the piston and the wheel support. 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 (4).