FR3134865A1 - DRUM BRAKE WITH REDUCED DUST EMISSION - Google Patents

Abstract

Drum brake for a motor vehicle comprising a plate (2) intended to be fixed to a steering knuckle of the vehicle and a drum (3) intended to be fixed to a wheel of the vehicle, the drum (3) and the plate (2) defining between them an interior volume (V), the brake comprising at least one segment movably mounted on the plate (2) so as to be able to come into contact with the drum (3), at least one actuator configured to move the segment in the direction of the drum, and means (14) for retaining the dust generated by said at least one segment to retain at least part of the dust in the interior volume (V) of the brake. [Fig 3A]

Description

DRUM BRAKE WITH REDUCED DUST EMISSION TECHNICAL FIELD AND PRIOR ART

The present invention relates to a drum brake for a motor vehicle.

A motor vehicle is equipped with a brake on each of its wheels. It can be a disc brake or a drum brake.

The drum brake has a plate for attaching to a wheel spindle and a drum for attaching to the wheel. The drum has a bottom and a side wall.

In addition, the drum brake comprises linings and one or more actuators carried by the plate, the linings are intended to come into contact with the interior surface of the side wall of the drum under the action of the actuator. The actuator(s) may be a hydraulic, electric or mechanical actuator.

When the drum is mounted on the platen, the linings and actuator(s) are in a relatively enclosed space.

When the drum brake is activated and the linings rub against the drum, the linings wear and generate fine particles or dust which are dispersed on the side of the roads.

However, this dust is a source of pollution.

It is generally desirable to reduce sources of pollution.

It is therefore an aim of this application to offer a drum brake releasing less pollution.

The aim stated above is achieved by a drum brake comprising a plate carrying the linings and the at least one actuator, a drum and retaining means interposed between the drum and the plate ensuring at least partial retention of the dust generated by the linings inside the brake.

The inventors thought of managing the problem of dust resulting from wear of the brake linings and of using the configuration of the plate and the drum which partially enclose the linings.

So little or no dust generated by the linings escapes from the drum brake. The dust remains contained between the plate and the drum. This dust is then collected during drum brake maintenance.

For example, the retaining means include a lip seal fixed to the drum or plate.

In another example, the retaining means includes foam which forms a barrier for dust while allowing water and air to circulate. In addition, the use of foam reduces the risk of overpressure appearing in the brake.

In other words, a drum brake is created defining a space around the linings that is airtight or almost airtight against dust resulting from wear of the linings.

A subject of the present application is a drum brake for a motor vehicle comprising a plate intended to be fixed to a steering knuckle of the vehicle and a drum intended to be fixed to a wheel of the vehicle, the drum and the plate defining between them a volume interior, the brake comprising at least one segment movably mounted on the plate so as to be able to come into contact with the drum, at least one actuator configured to move the segment in the direction of the drum, characterized in that it comprises retaining means dust generated by said at least one segment, to retain at least part of the dust in the interior volume of the brake.

In an exemplary embodiment, the retaining means comprise an annular fixing element to the plate or to the drum and a closing element in contact with the drum or the plate respectively closing or at least reducing the passage between the drum and the plate.

Advantageously, the fixing element comprises a metal reinforcement

The retaining means are preferably made of a flexible material comprising at least one elastomer, plastomer, mixture or alloy thereof.

In one example, the fixing element comprises a groove receiving an external contour of the plate or the drum.

In another example, the drum or the plate comprises an annular housing receiving the fixing element .

The closure element may include at least one lip. Very advantageously, the drum brake comprises elastic means so as to confirm the contact of the at least one lip with the drum or the plate.

In another example, the closure element is made of foam, advantageously open cell foam.

In another exemplary embodiment, the dust retaining means are entirely made of foam and fill the space between the radially outer part of the drum and a radially outer part of the plate.

BRIEF DESCRIPTION OF THE FIGURES

The description which follows will be better understood with the help of the appended drawings in which:
is a perspective view of an example of a drum brake to which the invention applies,
is a front view of the drum brake of the , the drum being omitted,
is a partial longitudinal sectional view of a drum brake according to an exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the ,
is a partial longitudinal sectional view of a drum brake according to another exemplary embodiment,
is a partial longitudinal sectional view of a drum brake according to an alternative embodiment of the brake of the .

DETAILED DESCRIPTION OF EMBODIMENTS

In Figures 1 and 2, we can see an example of a drum brake to which the invention applies.

Such a drum brake, marked with 1 on the , comprises a plate 2 of revolution of axis AX equipped with first and second segments in the form of an arc of circles 4 and 4' mounted movably relative to the plate 2 so as to be able to be pressed against the cylindrical internal face of a drum 3.

The segments 4 and 4' each comprise a core 4a, 4a' of flat sheet metal in the form of a portion of a circular ring which carries a braking lining 4b, 4b', and are mounted diametrically opposite with their ends bearing at the same time on a hydraulic wheel cylinder 6 and on a mechanical actuator 7 carried by the plate 2. These segments 4 and 4 'are also returned towards each other by two return springs 8 and 9, and pressed against the plate 2 each by a spring.

A wear compensation link 12 extends along the wheel cylinder 6 having a first end bearing on the core 4a of the first segment 4 and a second end bearing on the core 4a' of the second segment 4 '. The wheel cylinder 6 is intended to be actuated when using the drum brake 1 according to a first operating mode called "simplex", which ensures progressive braking particularly suitable for braking the vehicle in use. It includes a hydraulic chamber closed at its ends by two pistons which move away from each other when the hydraulic pressure increases and pushes the associated ends of segments 4 and 4’.

The mechanical actuator 7 provides, for its part, parking and emergency braking by moving the associated ends of the segments apart to ensure rapid and powerful blocking of the vehicle wheels in a so-called "duo-servo" operating mode, particularly when wheel cylinder 6 is inactive. This actuator is driven by an electric motor (not visible).

The drum has a bottom 3.1 with axis AX and a tubular side wall 3.2.

Tray 2 has a bottom 2.1 and a rim.

On the , we can see an example of a drum brake of the first type designated FAT1 comprising the plate 2 and the associated drum 3.

The rim 2.2 of the plate is tubular with axis AX, and the drum 3 has a second side wall 3.3 with axis AX surrounding the first side wall 3.2. The tubular rim 2.2 of the plate is received between the first side wall 3.2 and the second side wall 3.3.

The second tubular side wall 3.3 is connected to the first tubular wall 3.2 at a longitudinal end 3.22 opposite to that oriented towards the plate 2.

When the drum is mounted on the plate, its side wall 3.2 fits inside the edge of the plate. The linings and the actuators 6 and 7 are housed in a space V between the drum and the plate.

On the , we can see an example of a second type drum brake designated FAT2 comprising a plate 102 and an associated drum 103.

The plate 102 comprises a rim 102.2 comprising a tubular part 102.21 with axis AX and an annular part 102.22 extending radially outwards from the free end of the tubular part 102.21. The drum 103 comprises a bottom 103.1, a tubular side wall 103.2 and an annular extension 103.3 extending radially outwards. The annular extension 103.3 is connected to the side wall 103.2 in a middle part of the side wall 103.2.

When the drum is mounted on the plate, its tubular side wall 103.2 fits inside the tubular part 102.21 of the plate. The linings and the actuators 6 and 7 are housed in a space V between the drum and the plate.

The drum is intended to rotate relative to the plate around the axis AX. A mounting and operating clearance j is provided between the free end of the side wall 3.2, 103.2 of the drum and the bottom 2.1, 102.1 of the plate.

According to the invention, means are provided between the drum and the plate to limit, or even prevent, dust resulting from wear of the linings from leaving space V.

The FAT1 drum brake of the includes dust retention means 14.

In this example, the retaining means 14 comprise an annular lip seal provided with a heel 18 configured to cover the free end of the second tubular side wall 3.3 and attach to the drum, and with an annular lip 20 s extending radially inwards from the radially interior wall of the heel 18. The lip 20 is in contact with the exterior face of the tubular rim 2.2.

In an exemplary embodiment, the fixing element is held by simple mechanical assembly, for example the fixing element is force-mounted on the free end of the side wall. Advantageously, an adhesive or snap-fastening means are used.

When the drum 3 rotates relative to the plate, the lip rubs on the drum and is kept in tight contact against the drum. Volume V housing the linings confines dust resulting from wear of the linings.

The lip seal is made of elastomer, plastomer, their mixture or their alloy. For example, the lip seal is made of soft polyvinyl chloride.

In another example, the seal is made of flexible self-lubricating material, for example self-lubricating rubber, having better wear resistance.

Advantageously, the seal comprises one or more reinforcements in a manner similar to the SPI seals used in particular to ensure sealing between moving parts, for example at the level of crankshafts or camshafts.

For example, the seal has a spring in the shape of an O-ring in the base of the lip creating a pressing pressure of the lip against the other part and a reinforcement in the heel.

It is possible that the seal has several lips.

On the , we can even see a variant of the drum brake of the in which the means 14 are mounted on the plate, more particularly on the free end of the tubular side wall 3.3 of the plate, and the lip is in contact with the exterior face of the first tubular side wall 3.2. Alternatively, the lip is in contact with the interior face of the second tubular wall 3.3.

The FAT drum brake of the comprises dust retaining means 114 similar to the means 14 and comprising a heel 118 configured to be mounted on the free end of the annular extension 103.3 of the drum. The means 114 comprise an annular lip 120 configured to come into contact with the annular part 102.22 of the plate 102.

The retaining means 114 are of similar structures to those of the means 14.

On the , we can see a variation of the brake of the , in which the retaining means 114' further comprise anti-splash means comprising an axial extension 121 of the heel 118 which surrounds the lip seal. The axial extension 121 forms a barrier against the liquid, for example water which can be projected around the brake and which can enter inside the drum brake.

On the , we can see a variant of the drum brake of the , in which retaining means 114 are mounted on the plate 102, more particularly on the free end of the annular part 102.22 of the plate and the lip is in contact with the facing face of the annular extension 102.22.

On the , we can see another embodiment of a FAT1 type drum brake comprising retaining means 214 mounted on the drum.

The drum comprises in the interior face of the second side wall 3.3 an annular groove 22 with axis AX in which the heel 218 of the retaining means 214 is housed.

Maintaining the retaining means in the groove is ensured by mechanical assembly. Advantageously, an adhesive can be provided between the heel and the groove, preferably of the peelable type. Alternatively, retaining means by snapping are implemented between the heel and the groove. This applies to all embodiments.

The retaining means 214 comprise an annular lip 220 coming into contact with the exterior face of the tubular rim 2.2.

The annular groove 22 is for example produced by machining or directly during the molding of the drum which is generally made of cast iron.

Alternatively, the groove 22 is made in the exterior face of the first side wall 3.2 and the lip comes into contact with the interior face of the tubular rim 2.2 of the plate 2.

On the , we can see a variation of the drum brake of the in which the plate has a circular groove 24 of axis tubular 3.2 of the drum. The lip 320 comes into contact with the free end of the first tubular side wall 3.2 of the drum.

The tray is generally made by stamping a sheet metal. The groove 24 is advantageously also produced by stamping simultaneously with the rest of the plate.

On the we can see a FAT2 type drum brake according to another exemplary embodiment, in which the dust retaining means 414 are mounted on one face of the free end of the annular extension 103.3 of the drum, facing the part annular 102.22 of the plate 102. The heel 418 of the retaining means is fixed to the face of the annular extension and the lip 420 is in contact with the annular part 102.22. For example, the heel 418 is received in an annular groove 26 with axis AX formed in the face of the annular extension 103.3, for example by machining.

On the we can see a variation of the brake of the , in which the heel 418 of the retaining means 414 is fixed on the annular part 102.22 of the plate and the lip 420 rubs against the facing face of the annular extension 103.3. In the example shown and advantageously, the heel is mounted in an annular groove 28 formed in the annular part of the plate.

On the , we can see a drum brake FAT1 according to another embodiment in which the retaining means 514 comprise foam.

In the present application, the term “foam” means a polymer material whose cells, open or closed, are produced by the chemical or physical expansion of a gas.

The foam of the retaining means 514 covers the tubular rim 2.2 of the tray and fills the clearance between the tubular rim 2.2 of the tray and the first side wall 3.2 of the drum 3, and the clearance between the tubular rim 2.2 of the tray 2 and the second wall side 3.3 of the drum 3.

The use of foam retaining means has the advantage of ensuring the presence of a permanent barrier for dust regardless of the deformation that the plate and drum may experience due to thermal expansion.

Very advantageously, the foam used is an open cell foam which offers air permeability. The foam then allows air circulation between the inside and outside of the brake, which ensures cooling, unlike the retaining means forming a waterproof seal. In addition, this air permeability prevents the appearance of overpressure in the drum brake. In addition, open cell foam can allow water that may have accumulated in the brake to pass through, while forming a barrier against water splashing on the brake.

Alternatively, the foam is present only between the tubular rim 2.2 of the tray and the first side wall 3.2 of the drum or between the tubular rim 2.2 of the tray and the second side wall 3.3 of the drum.

In this example, the foam is preferably secured to the plate.

On the , we can see the FAT2 brake implementing the foam retaining means 514'. The foam extends between the edge of the plate and the part of the drum facing it. The foam can extend more or less between the plate and the drum.

In this example, the foam is secured to the plate or the drum, for example by means of an adhesive.

On the , we can see another example of a FAT1 brake comprising dust retaining means 614 comprising an annular fixing element or heel 614.1 retaining means to the plate and a foam element 614.2 ensuring dust retention. The foam is identical or similar to that of the examples in Figures 7A and 7B. In this example, the fixing element 614.1 comprises a ring whose cross section is U-shaped which covers the free end of the side wall 2.2 of the plate, the foam element 614.2 is in contact with the exterior face of the first side wall of the drum. Alternatively, the foam element is in contact with the interior face of the second side wall of the drum.

The retaining means 614 have the same advantages as the entirely foam means 514 and 514'.

On the we can see a variation of the brake of the , in which the retaining means 614 are mounted on the free end of the second side wall of the drum and the foam element is in contact with the exterior face of the side wall 3.3 of the plate. The fixing element covers the free end of the second side wall of the drum and the foam element is in contact with the exterior face of the side wall of the plate.

The fixing element is for example made of plastic material, for example polyvinyl chloride.

In an exemplary embodiment, the fixing element is held by simple mechanical assembly, for example the fixing element is force-mounted on the free end of the side wall. Advantageously, an adhesive or snap-fastening means are used. This also applies to the retaining means of Figures 9A to 11B.

On the , we can see another embodiment of a FAT2 brake, in which the dust retaining means 714 are mounted on the free end of the annular part 102.22. Similar to the means 614, the means 714 comprise an annular fixing element 714.1 and a foam element 714.2. The fixing element comprises an annular heel provided with an annular groove opening radially inwards and receiving the outer contour of the annular part 102.22. The foam element is in contact with the underside of the annular extension 103.3 of the drum. The material of the 714.1 fixing element has a certain elasticity to allow its mounting on the outer contour of the plate.

On the we can see a variation of the brake of the , in which the retaining means 714 are mounted on the radially outer contour of the annular extension 103.3. The ring-shaped fixing element 714.1 comprises an annular groove open radially inwardly housing the contour of the annular extension 103.3. The foam element 714.2 is in contact with the upper face of the annular part 102.22 of the plate.

In order to simplify assembly, it can be envisaged that the retaining means comprise two arcuate parts which attach to each other to close the circle and cover the entire external contour of the drum or plate.

On the , we can see another example of a FAT1 type drum brake comprising dust retention means 814 comprising an annular fixing element 814.1 and an annular foam element 814.2. The fixing element 814.1 is fixed on the interior face of the plate 2 to the right of the free end of the first side wall 3.2 of the drum so that the foam element 814.2 is in contact with this free end. Advantageously, the interior face of the plate 2 has an annular groove 30 housing the fixing element.

On the we can see a variation of the brake of the , in which the retaining means are fixed on the second side wall of the drum. The retaining means 814 comprise an annular fixing element 814.1 fixed at the level of the free end of the second side wall of the drum, so that the foam element 814.2 is in contact with the exterior face of the tubular wall 2.2 of the plateau. Advantageously, an annular groove 32 is made in the second side wall. Alternatively, the fixing element is attached to the exterior face of the first side wall so that the foam element is in contact with the interior face of the tubular wall.

On the , we can see another example of a FAT2 drum brake comprising dust retaining means 914 comprising an annular fixing element 914.1 and an annular foam element 914.2, similar to the retaining means 814. The fixing element 914.1 is fixed on the interior face of the bottom 2.1 of the plate 2 to the right of the free end of the first side wall 3.2 of the drum so that the foam element 914.2 is in contact with this free end. Advantageously, the interior face of the plate has an annular groove 34 housing the fixing element.

On the we can see a variation of the brake of the , in which the retaining means 914 are fixed on the annular extension 103.3 of the drum. The annular fixing element 914.1 is fixed on the lower face of the annular extension 103.3 of the drum facing the annular part of the plate, so that the foam element 914.2 is in contact with the annular part 102.22 of the plate. Advantageously, an annular groove 36 is made in the lower face of the annular extension 103.3 to accommodate the fixing element. Alternatively, the fixing element is fixed to the upper face of the annular part of the plate.

When the brake is serviced, particularly to replace the brake shoes, the dust that has been retained in the brake is collected and treated. Preferably, the used dust retaining means are replaced by new retaining means. Indeed, it is possible that the friction of the drum or the plate on the retaining means wears them out. Furthermore, in the case of retaining means comprising a foam part, the foam can become clogged after a certain time.

The invention makes it possible to limit the release of particles from drum brakes in a very simple manner and without impacting the operation of the brake. In fact, the friction generated by the retaining means between the two relative moving parts of the brake is very low.

It will be understood that the implementation of retaining means is not limited to the FAT1 and FAT2 drum brake but to any type of drum brake.

The present invention applies to the hydraulically and/or electrically actuated drum brake, comprising or not a mechanical or electric parking brake system.

Reference list

2, 102: tray

2.2: tubular rim, side wall, tubular wall

3, 103: drum

3.1, 2.1, 103.1, 102.1: background

3.2: first tubular side wall

3.3: second tubular side wall

3.22: longitudinal end

4: first segment in an arc of circles

4’: second segment in an arc of circles

4a, 4a’: soul

4b: flat sheet in the shape of a portion of a circular crown

4b’: braking lining

6: wheel cylinder, actuator

7: mechanical actuator

8, 9: return springs

10, 11: spring

12: wear compensation link

14, 114, 114’, 214, 314, 414, 514, 514’, 614, 714, 814: retaining means

18, 118, 218, 318, 418: annular fastener, heel

20, 120, 220: annular lip, closing element

22: annular groove

24: circular groove

26, 30, 32, 34, 36: annular groove

102.2: ledge

102.21: tubular part

102.22: contact with annular part

102.22: annular extension

103.3: annular extension

103.2: tubular side wall

121: axial extension

320, 420: lip

614.1, 714.1, 814.1, 914.1: annular fixing element

614.2, 714.2, 814.2: foam element

914: dust retention means

AX: axis

V: interior volume

FAT1: first type drum brake

FAT2: second type drum brake.

Claims (10)

Drum brake for a motor vehicle comprising a plate (2) intended to be fixed to a steering knuckle of the vehicle and a drum (3) intended to be fixed to a wheel of the vehicle, the drum (3) and the plate (2) defining between them an interior volume (V), the brake comprising at least one segment movably mounted on the plate (2) so as to be able to come into contact with the drum (3), at least one actuator configured to move the segment in the direction of the drum, characterized in that it comprises means (14) for retaining the dust generated by said at least one segment, to retain at least part of the dust in the interior volume (V) of the brake. Drum brake according to claim 1, in which the retaining means comprise an annular fixing element (18) to the plate (2) or to the drum (3) and a closing element (20) in contact with the drum (3) or the plate (2) respectively closing or at least reducing the passage between the drum (3) and the plate (2). Drum brake according to claim 2, in which the fixing element comprises a metal reinforcement. Drum brake according to claim 3, in which the retaining means are made of a flexible material comprising at least one elastomer, plastomer, mixture or alloy thereof. Drum brake according to claim 2, 3 or 4, in which the fixing element comprises a groove receiving an external contour of the plate or the drum. Drum brake according to one of claims 2 to 4, in which the drum or the plate comprises an annular housing receiving the fixing element . Drum brake according to one of claims 2 to 6, in which the closing element comprises at least one lip. Drum brake according to claim 7, comprise elastic means so as to confirm the contact of the at least one lip with the drum or the plate. Drum brake according to one of claims 2 to 6, in which the closing element is made of foam, advantageously of open cell foam. Drum brake according to claim 1, wherein the dust retaining means are made entirely of foam and fill the space between the radially outer part of the drum and a radially outer part of the plate.