WO2023152095A1

WO2023152095A1 - Clamping device for a braking system

Info

Publication number: WO2023152095A1
Application number: PCT/EP2023/052883
Authority: WO
Inventors: Philippe Bourlon; Cyril Cubizolles
Original assignee: Hitachi Astemo France
Priority date: 2022-02-09
Filing date: 2023-02-06
Publication date: 2023-08-17
Also published as: FR3132549A1

Abstract

The invention relates to a clamping device (6) for a braking system (2) intended to exert a relative movement between friction elements (4A, 4B) and comprising an assembly (7) bearing: - a clamping force application member (9) for applying a clamping force to at least one of the friction elements (4A, 4B), and - electromechanical means (11) for moving the clamping force application member (9). The clamping device (6) comprises vibration damping means (25, 26) arranged around at least one rotating member (15, 20) of the electromechanical means (11), between this rotating member (15, 20) and a fixed part (10, 16) of the assembly (7).

Description

Clamping device for braking system

The invention relates to the field of braking systems for vehicles, more particularly braking systems of the electromechanical type.

A disc-type braking system, in particular for a motor vehicle, generally comprises mechanical clamping means comprising in particular friction elements, such as brake pads, and a clamping device intended to exert a relative movement between these elements. friction. This clamping device comprises a yoke assembly provided with a yoke, fixed or floating, which carries at least one clamping force application member to at least one of the friction elements. This clamping force application member is intended to clamp this friction element against a disc secured to a wheel of the vehicle, to brake the wheel.

The force application member, also called the piston, can be controlled by hydraulic or electromechanical means.

In the case of a control of the force application member by electromechanical means, the yoke assembly comprises electromechanical means for moving the clamping force application member comprising at least one electric actuator, such as an electric motor, provided with a rotating shaft. A motion conversion mechanism, usually comprising a gear train and a worm gear system, converts the rotational motion of the electric actuator shaft into the translational motion of the friction element. Typically, the yoke assembly includes a body, integral with the yoke, which forms a housing for the motion conversion mechanism. The electric actuator is arranged in a box integral with this body.

It can be seen that this type of braking system produces noise of structural and aerial origins which propagate in the vehicle in particular through the fixed parts (that is to say integral with the caliper) of the caliper assembly , in particular through the body in which the motion conversion mechanism is housed and through the casing in which the electric actuator is housed.

Indeed, on the one hand, the gear train of the conversion mechanism generates structure-borne noise due to the vibration of moving mechanical parts and to shocks and/or friction between these parts. In general, the higher the conversion ratio, the higher the noise intensity. On the other hand, the electric motor generates airy whistling noises due to the micrometric deformation of the rotor under the effect of the excitation created by the magnetic field. These hissing noises are mainly propagated in empty spaces inside the braking system.

The noises generated by these braking systems are relatively weaker than those generated by a heat engine of a motor vehicle, so that their relative nuisance can generally be neglected in a vehicle with a heat engine. On the other hand, an electric motor intended to propel a motor vehicle generates much less noise than a heat engine. Consequently, the relative nuisance of the noises generated by electromechanically controlled braking systems cannot be neglected in a vehicle propelled by an electric motor.

The aim of the invention is in particular to limit the noise pollution mentioned above with regard to an electromechanically controlled braking system, by proposing a clamping device for a braking system which is quieter.

To this end, the subject of the invention is a clamping device for a braking system intended to exert a relative movement between friction elements and comprising an assembly carrying:

- a clamping force application member to at least one of the friction elements, and

- electromechanical means for moving the clamping force application member,

the clamping device further comprising vibration damping means arranged around at least one rotating member of the electromechanical means, between this rotating member and a fixed part of the assembly.

The damping means thus make it possible to limit, or even prevent, noise of solid-borne and/or aerial origins produced by the rotating member of the electromechanical means from propagating in the vehicle through fixed parts of an assembly at bracket, for example through a body in which is housed a movement conversion mechanism of the electromechanical means and through a housing in which is housed an electric actuator of the electromechanical means.

The invention applies to any type of braking system, in particular those intended to equip motor vehicles of the passenger car type, SUVs ("Sport Utility Vehicles"), two-wheelers (in particular motorcycles), airplanes, industrial vehicles chosen from vans , "Heavy-duty vehicles" - i.e. metro, bus, road transport vehicles (trucks, tractors, trailers), off-road vehicles such as agricultural or civil engineering machinery -, or other vehicles transportation or handling. The invention also applies to non-motorized vehicles such as in particular a trailer, a semi-trailer or a caravan.

Following other optional features of the clamping device taken alone or in combination:

- The electromechanical means comprise an electric motor comprising a stator and a rotor, the damping means being arranged between the rotor and a wall surrounding this rotor of a box in which the electric motor is arranged.

Thus, in the case of noise generated by the micrometric deformation of the rotor under the effect of the excitation of the magnetic field, the damping means make it possible to isolate the motor from its casing and thus to attenuate the amplitude of the waves acoustic propagating in the space around the rotor.

It is understood that the housing in which the electric motor is arranged is part of the assembly of the clamping device which usually comprises a stirrup, for example a floating stirrup movable with respect to a yoke, and means for coupling the electric motor with the clamping force application member. The box, fixed to the stirrup, is also movable in translation relative to the yoke, together with the stirrup. This housing constitutes a fixed part of the assembly of the clamping device within the meaning of the present invention, in particular because it is not linked to the movements transmitted between the motor and the force application member.

The rotor forming part of the electromechanical means constitutes a rotating member capable of generating noise and comprises, for example, a rotating cage in which are arranged electromagnetic members configured to be electromagnetically coupled to complementary electromagnetic members carried by the stator of the electric motor. The electromagnetic members comprise for example magnets and/or windings.

- The damping means comprise a vibration damping pad propagating by air housed in at least one perforated cartridge for the passage of air vibrations.

The gasket allows noise from the engine to be absorbed as it passes through the cartridge. The perforated cartridge has openings that facilitate the passage of noise into the trim.

It is understood that the cartridge carrying the lining is spaced from the rotor by a minimum clearance, for example 0.5 mm, to allow rotation of the rotor around the stator.

- The lining comprises at least one material chosen from steel or aluminum wool, polymer fibers and rock wool.

- The damping means comprise at least two cartridges, the two linings housed respectively in these two cartridges being made of different materials.

This makes it possible to offer a damping solution using several types of linings of different materials and/or densities in the same clamping device, the variety of materials thus being able to be adapted to the variation in noise coming from the engine.

- The electromechanical means comprise a gear train comprising at least one rotating toothed member, the damping means being arranged between two fixed coaxial surfaces of the assembly so as to delimit open spaces between these surfaces.

Thus, to attenuate the noise generated by the gear train, the damping means provide axial and radial sealing between the two fixed coaxial surfaces of the assembly.

The gear train includes, for example, an epicyclic gear train comprising a central pinion coupled to the motor (also called "planet"), a mobile crown forming a rotating toothed member likely to generate noise, and pinions (also called "satellites") meshing with the central pinion and the mobile crown. In this case, the damping means make it possible to isolate the mobile crown as well as the entire gear train from the rest of the clamping device and thus reduce the noise coming from the rotating toothed member.

- The damping means comprise an elastically deformable sleeve at least radially interposed between two fixed coaxial surfaces of the assembly so as to damp the structure-borne vibrations propagating between these fixed coaxial surfaces.

The sleeve being in contact with two fixed coaxial surfaces, the vibrations passing from one surface to the other change frequency while passing through the elastically deformable sleeve and are thus damped. In addition, this solution requires a reduced number of parts and simple assembly, which makes it possible to produce the clamping device at low cost.

Open spaces can be formed in different ways. It is in particular possible to envisage annular hollows or beads on the outer and inner surfaces of the sleeve so that each surface has contact zones spaced apart by empty zones. It is also possible to provide cells in the mass of the sleeve. The spaced contact zones or the cells have the effect of creating an elastic displacement which makes it possible to further dampen the vibrations.

Alternatively, the clamping device may comprise a plurality of sleeves forming O-rings which are connected to each other;

- The two fixed coaxial surfaces of the assembly respectively delimit a fixed ring gear and a body integral with a bracket carrying the clamping force application member.

It is understood that the fixed ring gear surrounds the rotating toothed member with which, for example, it meshes.

- The damping means comprise an elastomer material or a plastomer material or a mixture of the two.

- The damping means are in a compressed state between the two fixed coaxial surfaces, when the clamping device is in operation, for better damping of vibrations and better reduction of structure-borne noise.

The invention also relates to a braking system for a vehicle comprising two friction elements intended to cooperate by friction with a disc, this braking system comprising at least one tightening device as defined above for tightening the two friction elements respectively to two opposite sides of the disc.

Another subject of the invention is a vehicle comprising a braking system as defined above.

Brief description of figures

The invention will be better understood on reading the following description given solely by way of example and made with reference to the appended drawings in which:

there is a schematic top view of a vehicle in which a braking system according to the invention is mounted;

there is a schematic view of a braking system to which the invention can be applied;

there is a perspective view of a clamping device according to the invention;

there is a sectional view according to plan IV-IV of the ;

there is an exploded perspective view of part of the clamping device of the ;

there is a detail view of the section according to plan IV-IV of the .

detailed description

We represented on the a motor vehicle 1 in which a braking system 2, of the electromechanical type, according to the invention, is arranged on each of the four wheels 3.

On the , a braking system 2 has been schematized to which the invention, which will be described in more detail below, is applied. This braking system 2 is of the floating caliper disc type. It comprises at least two friction elements 4A, 4B intended to cooperate by friction respectively with two opposite faces FA, FB of a disk 5, integral in rotation with a wheel 3 of the vehicle.

The braking system 2 is of the electromechanical type. It comprises a clamping device 6 provided with a stirrup assembly 7 comprising a floating stirrup 8 carrying a member 9 for applying clamping force to one of the friction elements 4A. The clamping force application member 9 is also called "piston 9" in the following. It will be noted that, as a variant, the invention also applies to a fixed-caliper braking system. In this case, the clamping device 6 comprises two members 9 for applying force respectively to the two friction elements 4A, AB.

The clamping device 6 is intended, by exerting a relative movement between the two friction elements 4A, 4B, to clamp these two friction elements 4A, 4B respectively towards the two opposite faces FA, FB of the disc 5.

Referring to Figures 3 and 4, in which the clamping device 6 has been shown in more detail according to one embodiment of the invention, it can be seen that the latter further comprises a body 10, integral with the stirrup 8 , in which are arranged electromechanical means 11 for moving the piston 9. The stirrup 8 is slidably mounted on the columns of a yoke 12 so as to be able to move in translation in an axial direction A (shown in FIGS. 2 and 4 with a dashed line) in relation to the yoke 12.

By referring to the , it is seen that the electromechanical means 11 comprise an electric actuator which is, in the example shown, an electric motor 13 actuating the two friction elements 4A, 4B. The electric motor 13 comprises a stator 14 and a rotor 15 capable of rotating around the stator 14 under the effect of a magnetic field. The electric motor 13 is housed in a casing 16, integral with the body 10, which is therefore fixed with respect to the stirrup 8. It will be noted that the rotor 15 is a rotating member capable of generating noise.

Such a clamping device 6, of the floating yoke type, makes it possible to use only one electric actuator and thus to be more compact.

As shown in , the electromechanical means 11 comprise a mechanism 17 for converting the rotational movement of an output shaft 18 of the electric motor 13 into a translational movement of the piston 9 in the axial direction A. In the example illustrated in , the conversion mechanism 17 comprises a gear train 19 comprising, for example, an epicyclic gear train. The gear train 19 forms a reducer.

In gear train 19 as seen in , the movement of the output shaft 18 of the electric motor 13 is first transmitted to a central pinion coupled to the output shaft 18. Using a set of toothed wheels, the rotary movement of the central pinion of the gear train 19 is transmitted to a movable crown 20 forming a rotating toothed member capable of generating noise. This mobile crown 20 is for example housed in a fixed toothed crown.

The conversion mechanism 17 further comprises a ball screw system comprising a nut 22 cooperating with a screw 23 via balls 24. In the example illustrated, the mobile crown 20 and the nut 22 are coupled in rotation so as to transmit to the screw 23 a translational movement in the axial direction A when the nut 22 is rotated.

It will therefore be noted that the screw 23 is movable, inside the body 10, in translation parallel to its axis A, and that the nut 22 is movable in rotation, inside the body 10, around its axis which coincides with that of the screw 23. The nut 22 is immobilized in translation in the body 10 using means known per se.

The piston 9, which is connected in translation with one end 23A of the screw 23, moves integrally in translation with this screw 23, in the axial direction A. It is therefore obtained, during the rotation of the nut 22, a relative displacement movement between the friction elements 4A, 4B in the substantially rectilinear axial direction A.

In order to reduce noise pollution, the clamping device 6 further comprises vibration damping means 25, 26 which are arranged around at least one rotating member 15, 20 of the electromechanical means 11, between this rotating member 15, 20 and a fixed part of the stirrup assembly 7.

According to a first variant of the embodiment of the invention as illustrated, the damping means 25 are arranged between the rotating member formed by the rotor 15 and a fixed wall of revolution 16F of the housing 16 in which the electric motor 13 (see ). As can be seen more clearly in the , these damping means 25 comprise a packing 27 for damping vibrations propagating by air. The lining 27 is housed in at least one perforated cartridge 28 for the passage of air vibrations. The lining 27 comprises at least one material selected from steel or aluminum wool, polymer fibers and rock wool. The lining 27 has an optimum density for the absorption of noises that those skilled in the art will be able to define according to the material chosen.

According to this first variant (see ), the damping means 25 comprise a plurality of cartridges 28, for example six in number. Each cartridge 28 has a curved shape and is held in the housing 16 by ribs 29 extending at least partially from the wall 16F of the housing 16. The cartridges 28, once all arranged in the housing 16, form a set of damping of revolution around the rotor 15 of the electric motor 13.

Advantageously, according to this first variant illustrated in , the damping means 25 comprise at least two types of linings, so that two linings 27 housed respectively in two different cartridges 28 are made of different materials

According to a second variant of the embodiment of the invention as illustrated, the damping means 26 are arranged between two fixed coaxial surfaces 21F, 10F of the stirrup assembly 7 so as to delimit between these fixed coaxial surfaces 21F , 10F of open spaces. More precisely, and as can be seen in FIGS. 4 and 6, the two fixed coaxial surfaces 21F, 10F of the assembly 7 respectively delimit the fixed ring gear 21 and the body 10 secured to the stirrup 8. Thus, the means of damping 26 according to this second variant are arranged in the space delimited by the body 10, the fixed toothed crown 21, the housing 16 and a small portion of the movable crown 20. In addition, as can be seen in Figures 4 and 6 , the damping means 26 occupy substantially all of said space.

According to the example illustrated in Figures 4 and 6 of the second variant of the invention, the damping means 26 comprise an elastically deformable sleeve 30 at least radially interposed between the two fixed coaxial surfaces 21F, 10F of the assembly 7 to stirrup so as to dampen the structure-borne vibrations propagating between these fixed coaxial surfaces 21F, 10F. To do this, in this variant, the sleeve 30 comprises an elastomeric material or a plastomeric material or a mixture of the two. Advantageously, the sleeve 30 is also elastically deformable in an axial direction.

Furthermore, in the same example illustrated, the sleeve 30 has beads on the outer and inner surfaces of the sleeve 30 so that the sleeve 30 forms with each of the fixed coaxial surfaces 21F, 10F a discontinuous contact surface. These beads make it possible to alternate free spaces with zones of contact of the sleeve 30 with coaxial surfaces 21F, 10F. Alternatively, it is also possible to provide cells in the mass of the sleeve 30 in addition to the beads or instead of them.

The invention is not limited to the embodiments shown and other embodiments will be apparent to those skilled in the art. Thus, the embodiments and variants can be combined with each other without departing from the scope of the invention. Hopefully, it is possible for the clamping device to include both the damping means for the electric motor and the damping means for the gear train.

List of references

1: motor vehicle
2: braking system

3: wheels

4A, 4B: friction elements

5: disk

6: clamping device

7: together

8: stirrup

9: clamping force application device

10: body, fixed part

10F: fixed coaxial surface

11: electromechanical means

12: clevis

13: electric motor

14: stator

15: rotor, rotating member

16: housing, fixed part

16F: wall

17: conversion mechanism

18: output shaft

19: gear train

20: mobile crown, toothed component, rotating component

21: fixed ring gear

21F coaxial fixed surface

22: nut

23: screw

23A: end

24: marbles

25: damping means

26: damping means

27: garnish

28: cartridge

29: ribs

30: sleeve

FA, FB: opposite faces

A: axial direction

Claims

Clamping device (6) for a braking system (2) intended to exert a relative movement between friction elements (4A, 4B) and comprising an assembly (7) carrying:
- a clamping force application member (9) to at least one of the friction elements (4A, 4B), and
- electromechanical means (11) for moving the clamping force application member (9),
the clamping device (6) comprising vibration damping means (25, 26) arranged around at least one rotating member (15, 20) of the electromechanical means (11), between this rotating member (15, 20) and a fixed part (10, 16) of the assembly (7),
in which the electromechanical means (11) comprise an electric motor (13) comprising a stator (14) and a rotor (15), the damping means (25) being arranged between the rotor (15) and a wall surrounding this rotor (15) a casing (16) in which the electric motor (13) is arranged,
characterized in that the damping means (25) comprise a lining (27) for damping vibrations propagating by the air route housed in at least one cartridge (28) perforated for the passage of the air vibrations.
A clamp according to claim 1, wherein the liner (27) comprises at least one material selected from steel or aluminum wool, polymer fibers and rock wool.
Clamping device according to Claim 1 or 2, in which the damping means (25) comprise at least two cartridges (28), the two linings (27) housed respectively in these two cartridges (28) being made of different materials.
Clamping device according to Claim 1, in which the electromechanical means (11) comprise a gear train (19) comprising at least one toothed member (20) rotating, the damping means (26) being arranged between two coaxial surfaces fixed of the assembly (7) so as to delimit clear spaces between these surfaces.
Clamping device according to the preceding claim, in which the damping means (26) comprise an elastically deformable sleeve (30) at least radially interposed between the two fixed coaxial surfaces of the assembly (7) so as to damp the structure-borne vibrations propagating between these fixed coaxial surfaces.
Clamping device according to Claim 4 or 5, in which the two fixed coaxial surfaces of the assembly respectively delimit a fixed toothed crown (21) and a body (10) integral with a stirrup (8) carrying the application of clamping force (9).
A clamp according to any of claims 4 to 6, wherein the damping means (26) comprises an elastomeric material or a plastomeric material or a mixture of the two.
A clamp according to any of claims 4 to 7, wherein the damping means (26) is in a compressed state between the two fixed coaxial surfaces.
Braking system (2) for a motor vehicle (1) comprising two friction elements (4A, 4B) intended to cooperate by friction with a disc (5), characterized in that it comprises at least one tightening device ( 6) according to any one of the preceding claims to tighten the two elements (4A, 4B) of friction respectively towards two opposite faces of the disc (5).
Motor vehicle (1) characterized in that it comprises a braking system (2) according to the preceding claim.