WO2006018584A1

WO2006018584A1 - Clutch friction device, in particular for a motor vehicle and a clutch provided with said device

Info

Publication number: WO2006018584A1
Application number: PCT/FR2005/050625
Authority: WO
Inventors: Hugues Minereau; Olivier Fafet
Original assignee: Valeo Embrayages
Priority date: 2004-07-29
Filing date: 2005-07-27
Publication date: 2006-02-23
Also published as: CN1973145A; KR20070034608A; FR2873774B1; BRPI0512384A; DE112005001863T5; FR2873774A1

Abstract

The inventive friction device consists of two friction linings and a support (28) comprising a hub (34) which is radially extended by at least one peripheral blade (36) delimited by two angular edges (38A, 38B) and comprises a bearing surface (44) connected to the first lining and at least one free bearing surface (46A, 46B, 55) contacting with the second lining. The connected (44) and free (46A, 46B) bearing surfaces are separated from each other by the blade slip (50A, 50B) which is delimited by two fold lines (52A, 54A; 52B, 54B). Each angular edge (38A, 38B) comprises a concave part (60A, 60B) delimiting the blade slip (50A, 50B) and the parts of the bearing (44) and free surfaces adjacent to the blade slip (50A, 50B). The concave part (60A, 60B) forms a concave curvature which delimits the blade slip (50A, 50B) at any point and comprises a tangent forming jointly with the fold line nearest to a point where the tangent is regarded an angle ranging from 70 to 110°.

Description

Friction device for a clutch, in particular for a motor vehicle, and clutch comprising such a device

The present invention discloses a friction device for a clutch, especially a motor vehicle, and a clutch comprising such a device.

In a motor vehicle, a clutch, single or double type, is intended to couple rotating members driving and driven substantially aligned axes of rotation. The rotary driving member is coupled to the engine, more particularly to a crankshaft of the engine, and the driven member is coupled to a gearbox shaft. The clutch comprises at least one mechanism driven in rotation by the driving member, this mechanism being fixed on a flywheel secured to the crankshaft. The mechanism comprises a lid, a diaphragm and a pressure plate all rotatably connected with the driving member.

The clutch further comprises a friction device comprising a friction disk rotatably connected to the driven member.

In order to couple the driving and driven rotary members, the diaphragm encloses the friction disk between the pressure plate and a reaction plate integral with the lid in rotation. In general, the reaction plate is formed by the flywheel.

The friction disc has a generally rotational support, carrying first and second friction linings respectively arranged on first and second bearing surfaces of the support. These first and second bearing faces are axially offset, so as to generate an axial flexibility between the first and second friction linings.

The axial offset of the first and second bearing faces, also called progressivity, allows low amplitude axial displacement of the first and second gaskets relative to each other when the friction disk is sandwiched between the pressure plate and the pressure plate. reaction tray. In general, the displacement of the first and second packings relative to each other is less than 1 mm, preferably between 0.5 and 0.7 mm. Clamping of the friction disk between the pressure plate and the reaction plate is controlled by a user of the motor vehicle by means of a foot pedal. The foot pedal is movable between a disengaged position, in which the friction disc is not clamped, and a clutch position, in which the friction disc is clamped. The displacement of the reaction plate relative to the pressure plate being related to the displacement of the control pedal, the progressiveness allows, during the clamping of the friction disc, a greater travel of the control pedal. In indeed, the axial displacement of the first and second packings relative to one another, during the progressive tightening of the pressure disk, causes an additional travel of the control pedal between the beginning and the end of the increase of the pressure. clamping force.

There are sometimes defects of parallelism between the pressure and reaction plates, for example during a rise in the temperature of the plates which causes deformations of these plates. In this case, the progressivity makes it possible to keep a friction force of the friction disc distributed substantially uniformly over each of the first and second friction linings. This uniform distribution of the clamping force is important to ensure a good life of the clutch. In order to ensure progressiveness, it has already been proposed in the state of the art, particularly in FR-A-2 693 778, a friction device for a clutch, in particular a motor vehicle, of the type comprising:

first and second friction lining, substantially annular and coaxial, and a support of general shape of revolution comprising a hub extended radially by at least one peripheral blade delimited by two angular edges, the blade comprising a bearing face connected to the first lining and at least one free span face in contact with the second liner, the bound and free bearing faces being separated from each other by an axial blade recess, delimited by two fold lines.

The axial blade recess formed in the support creates a spring effect between the first and second packings during their compression between the pressure and reaction plates. This spring effect ensures the progressive activation of the clutch.

However, it is desired to increase the engine torque transmitted by a clutch, without increasing the dimensions of this clutch, which must meet congestion constraints imposed by car manufacturers.

In order to increase the torque transmitted by the clutch, the clamping force applied by the pressure plate is generally increased. Furthermore, the friction linings being delimited by inner and outer spokes, a clutch generally comprises vibration damping means arranged on a radius smaller than the inner radius of the friction linings. Preferably, it will be chosen to increase the inner radius of the friction linings in order to accommodate damping means which are more bulky and therefore more effective. In this case, the surfaces of the friction linings decrease. The increase in the clamping force applied by the pressure plate and the reduction of the surfaces of the friction linings cause a significant increase in the pressure exerted on the linings, and therefore on the blade recess ensuring progressivity. Important stresses thus appear in certain parts of the blades of the support, in particular, the portions delimited by angular contours. These constraints induce greater fatigue work, faster wear, as well as risks of rupture.

The object of the invention is notably to remedy this premature wear of a friction device of a clutch intended for the transmission of high torques.

For this purpose, the subject of the invention is a friction device of the aforementioned type, wherein each angular edge comprises a concave portion delimiting the blade recess and portions of the bound and free span faces adjacent to this blade recess, the portion concave angular edge forming a concave curve which, at any point delimiting the blade recess, has a tangent forming an angle between 70 and 110 ° with the fold line closest to the point where the tangent is considered.

This shape of the blade is optimized so that the stresses in this blade are distributed as well as possible, which effectively limits the risk of rupture of the blade and increases the life of the friction device. A friction device according to the invention may further comprise one or more of the following features:

- any point of the concave curve defining the free span face has a tangent forming an angle between 70 and 110 ° with the fold line closest to the point where the tangent is considered; - The concave portion of the angular edge delimiting the free span face extends between the portion of the angular edge defining the blade recess and a straight portion of the angular edge coinciding substantially with a radius of the support; the concave portion of the angular edge delimiting the bonded bearing surface extends between the portion of the angular edge delimiting the blade recess and a portion of the angular edge delimiting an axial hub recess connecting the hub to the blade;

- The hub recess is delimited by two fold lines, any point of the concave portion of the angular edge defining the bound bearing face having a tangent forming an angle between 70 and 110 ° with the fold line delimiting the blade or hub recess, the closest to the point where the tangent is considered;

- The concave portion of the angular edge also defines the hub recess and a portion of the hub adjacent to the hub recess; the free span face of the blade is delimited by the angular edge of the blade and by a circular peripheral edge adjacent to this angular edge of the blade;

- The blade recess is defined by two substantially parallel fold lines inclined relative to a median radius of the blade at an angle between 40 and 50 °;

the blade comprises two free span faces delimited respectively by the two angular edges of the blade;

the blade comprises a face of free span formed on a tongue extending in a slot of the blade interposed angularly between the two free bearing faces delimited respectively by the two angular edges of the blade;

- The hub is extended radially by at least two adjacent peripheral blades defined respectively by two adjacent angular edges interconnected by a concave hub edge; the hub is extended radially by several peripheral blades, the blades connected to the first lining alternating with the blades connected to the second lining;

at least one annular friction lining is delimited by external and internal contours, such that the ratio of the diameter of the outer contour to the diameter of the inner contour is less than 1, 4, preferably less than 1, 35;

at least one friction lining is glued to the bonded surface face; the friction device comprises a wear compensating device. The invention also relates to a clutch for a motor vehicle comprising a friction device as described above.

Optionally, the clutch being intended to couple rotating members driving and driven, the driven rotary member is rotatably connected to an input shaft of an automatic gearbox. The invention will be better understood on reading the description which will follow, given solely by way of example and with reference to the appended drawings, in which: FIG. 1 is an axial sectional view of a friction device according to an embodiment of the invention; Figure 2 is a partial front view of a support of the friction device of Figure 1; Figure 3 is a view similar to that of Figure 2 of a friction device holder according to an alternative embodiment. FIG. 1 shows a friction device 10 for a clutch, in particular a motor vehicle.

The friction device 10 comprises a damper 12 for transmitting a torque of a driving member, such as a crankshaft of a motor vehicle engine, to a driven shaft, such as an input shaft a gearbox. For this purpose, the damper 12 is mounted between an input rotary element, such as a friction disc 14 which can be rotatably connected to the crankshaft, and a rotary output element, such as a cylindrical hub 16 can be rotatably connected to the gearbox input shaft. It will be noted that the input 14 and output 16 elements are substantially coaxial. The clutch comprises at least one mechanism (not shown) rotated by the driving member, this mechanism being fixed on a flywheel secured to the crankshaft. The mechanism comprises a lid, a diaphragm and a pressure plate all rotatably connected with the driving member.

In order to couple the driving and driven rotary members, the diaphragm encloses the friction disk 14 between the pressure plate and a reaction plate secured to rotate the lid.

The damper 12 is intended to filter vibrations coming from the engine of the motor vehicle. For this purpose, the damper 12 comprises damping means 17, interposed between guide washers 18 and 20, rotatably connected to the friction disk 14 by means of rivets 22, and a web 24, connected in rotation to the hub 16.

The friction disk 14 comprises a support 28 of generally circular shape, carrying first 30 and second 32 substantially annular and coaxial friction linings.

The support 28, shown in greater detail in FIG. 2, comprises a hub 34 extended radially by peripheral blades 36. Each peripheral blade 36 is delimited by two angular edges 38A and 38B and a circular peripheral edge 42 adjacent the angular edges 38A and 38B. It will be noted that two adjacent angular edges 38A, 38B of two adjacent peripheral blades 36 are interconnected by a concave edge 43 of the hub 34. Each blade 36 comprises a bearing surface 44 connected to the first pad

30, by means of conventional connecting means 45, and first and second faces of free span 46A, 46B in contact with the second liner 32. The bound bearing faces 44 and free 46A, 46B are separated from each other respectively by recesses. axial blades 5OA, 5OB. Each step 5OA, 5OB is delimited by two fold lines 52A, 54A, 52B, 54B.

Note that the support 28 comprises blades 36 connected to the first seal 30 alternating with the blades 36 connected to the second seal 32.

In the embodiment shown, the connecting means 45 are rivet attachment holes. Note that, in this case, a rivet head protrudes in the thickness of the friction lining 30, 32. As the lining 30, 32 wears out, its thickness decreases until, when the friction disk is clamped, the pressure plate (respectively reaction plate) comes into contact with the rivet head rather than with the gasket. The clutch can no longer function properly.

In order to increase the service life of the friction lining 30, 32, the connecting means may alternatively be gluing means. In this case, a greater thickness of the friction lining 30, 32 must be worn before the clutch is no longer functioning properly.

The fact that the friction lining 30, 32 is bonded to the support 28 also makes it possible to reduce the incrustation of the blades 36 in the friction lining 30, 32. Each free-span face 46A, 46B is delimited by an angular edge 38A,

38B of the blade 36 and the circular peripheral edge 42 adjacent to the corresponding angular edge 38A, 38B.

In general, the two fold lines 52A, 54A (respectively 52B, 54B) delimiting the recess 5OA (respectively 50B) are substantially parallel and inclined relative to a median radius of the blade 36 by an angle of between 40 and 50 ° preferably 45 °.

The blade 36 further comprises a third free-span face 55 formed on a tongue 56 extending in a slot 57 of the blade 36 interposed angularly between the two surfaces of free bearing surfaces 46A, 46B. The bounded bearing faces 44 and the third free-span face 55 are separated from each other by a recess 58.

This recess 58 is delimited by two fold lines 59I and 59E. In what follows, the shape of the blade 36 will be equated with the shape of the orthogonal projection of this blade 36 on a plane perpendicular to the axis of the friction disk 14, in particular the plane of FIG. 2.

Each angular edge 38A, 38B comprises a concave portion 6OA, 6OB delimiting the recess 5OA, 5OB blade and delimiting portions of the bearing faces 44 and free 38A, 38B adjacent to this recess 5OA, 5OB blade.

The concave portion 6OA, 6OB of the angular edge 38A, 38B forms a concave curve which, at any point delimiting the recess 5OA, 5OB blade, has a tangent forming an angle between 70 and 110 ° with the fold line 52A, 52B or 54A, 54B nearest the point where the tangent is considered.

It will be noted that the concave portion 6OA, 6OB of the angular edge 38A, 38B delimiting the free span face 46A, 46B extends between the portion of the angular edge delimiting the recess 5OA, 5OB blade and a straight portion 62A, 62B edge angular substantially coinciding with a radius of the support 28. Any point of the concave curve defining the free span face 46A, 46B has a tangent forming an angle between 70 and 110 ° with the fold line 52A, 52B.

Alternatively, as shown in FIG. 3, the free-span face 46A, 46B has a rounded edge 63A, 63B between the part of the angular edge delimiting the recess 5OA, 5OB of the blade and the rectilinear portion 62A, 62B of the edge. angularly coinciding substantially with a radius of the support 28

Furthermore, the concave portion 6OA, 6OB delimiting the bound bearing face 44 extends between the portion of the angular edge 38A, 38B delimiting the blade recess.

5OA, 5OB and a part of the angular edge 38A, 38B delimiting an axial hub recess 64A, 64B connecting the hub 34 to the blade 36. This hub recess 64A, 64B is delimited by two fold lines 66A and 68A, 66B and 68B.

Thus, any point of the concave portion 6OA, 6OB of the angular edge 38A, 38B delimiting the bound bearing face 44 has a tangent forming an angle between

70 and 110 ° with the fold line closest to the point where the tangent is considered, among the fold line 54A, 54B delimiting the blade recess 50A, 50B and the fold line 66A, 66B defining the recess 64A, 64B hub.

The concave portion 6OA, 6OB of the angular edge 38A, 38B also delimits the hub recess 64A, 64B and a portion of the hub 34 adjacent to the hub recess 64A, 64B.

This shape of the blade 36 is optimized so that the stresses in this blade 36 are distributed as well as possible, which effectively limits the risk of rupture of the blade 36 and increases the life of the friction device. Therefore, the active surfaces of the first and second friction liners can be reduced compared to those of conventional friction liners.

Thus, each annular friction lining 30, 32 being delimited by radially outer and inner contours, it will be preferable to choose a ratio of the outside diameter to the inside contour diameter of less than 1.4, for example less than 1, 35.

This makes it possible, with a diameter of the outer contour substantially identical with respect to a conventional lining, to increase the inside diameter of the lining so as to increase the space available for the damper 12.

Note that the blades 36 can accept a pressure greater than three bars. This makes it possible to increase the pressure force applied to each friction lining, a high pressure compensating for the small surface area of the friction linings.

The present invention contributes to increasing the life of the clutch. In order to optimize this increase in service life, the clutch advantageously comprises a device (not shown) for compensating for the wear of the friction linings 30, 32. It is recalled that a wear-compensating device allows the diaphragm of the clutch has a position when clamping the friction disc 14 which is substantially independent of the wear of the friction liners 30, 32. Note that the invention is particularly suitable for a clutch whose rotary member is driven linked in rotation to an input shaft of an automatic gearbox. Indeed, an automatic gearbox generally inducing a greater number of clutch actuation than a manual gearbox, it is advantageous that this clutch is less sensitive to wear, as is the case for a clutch according to the invention.

Claims

A friction device (10) for a clutch, in particular a motor vehicle, of the type comprising: first (30) and second (32) substantially annular and coaxial friction linings, and

a support (28) of general shape of revolution comprising a hub (34) extended radially by at least one peripheral blade (36) delimited by two angular edges (38A, 38B), the blade (36) comprising a bearing face ( 44) connected to the first liner (30) and at least one free span face (46A, 46B, 55) in contact with the second liner (32), the bound (44) and free (46A, 46B) bearing surfaces being separated from each other by an axial blade recess (5OA, 50B) delimited by two folding lines (52A, 54A; 52B, 54B), characterized in that each angular edge (38A, 38B) comprises a concave part (6OA , 60B) delimiting the blade recess (50A, 50B) and portions of the bound (44) and free (46A, 46B) bearing faces adjacent to this blade recess (50A, 50B), the concave portion (60A, 60B). ) of the angular edge (38A, 38B) forming a concave curve which, at any point delimiting the blade recess (50A, 50B), has a tangent forming an angle between 70 and 110 ° with the fold line (52A, 54A, 52B, 54B) closest to the point where the tangent is considered.

2. Device (10) according to claim 1, characterized in that any point of the concave curve defining the free span face (46A, 46B) has a tangent forming an angle between 70 and 110 ° with the fold line ( 52A, 52B) closest to the point where the tangent is considered.

3. Device (10) according to claim 1 or 2, characterized in that the concave portion (60A, 60B) of the angular edge (38A, 38B) delimiting the free span face (46A, 46B) extends between the portion angular edge (38A, 38B) delimiting the blade recess (50A, 50B) and a straight portion (62A, 62B) of the angular edge (38A, 38B) substantially coinciding with a radius of the support (28).

4. Device (10) according to any one of the preceding claims, characterized in that the concave portion (60A, 60B) of the angular edge delimiting the bonded bearing surface (44) extends between the portion of the angular edge defining the blade recess (50A, 50B) and a portion of the angular edge defining a recess (64A, 64B) axial hub connecting the hub (34) to the blade (36).

5. Device (10) according to claim 4, characterized in that the hub recess (64A, 66B) is delimited by two fold lines (66A, 68A, 66B, 68B), any point of the concave portion (6OA, 60B) of the angular edge (38A, 38B) delimiting the bound bearing face (44) having a tangent forming an angle between 70 and 110 ° with the fold line, delimiting the blade recess (54A, 54B) or hub (66A, 66B), the closest to the point where the tangent is considered.

6. Device (10) according to claim 4 or 5, characterized in that the concave portion (60A, 60B) of the angular edge (38A, 38B) also defines the hub recess (64A, 64B) and a portion of the hub ( 34) adjacent this hub recess (64A, 64B).

7. Device (10) according to any one of the preceding claims, characterized in that the free span face (46A, 46B) of the blade (36) is delimited by the angular edge (38A, 38B) of the blade ( 36) and a circular peripheral edge (42) adjacent this angular edge (38A, 38B) of the blade (36).

8. Device (10) according to any one of the preceding claims, characterized in that the blade recess (50A, 50B) is defined by two fold lines (52A, 54A, 52B, 54B) substantially parallel inclined with respect to a median radius of the blade (36) at an angle between 40 and 50 °.

9. Device (10) according to any one of the preceding claims, characterized in that the blade (36) comprises two free bearing surfaces (46A, 46B) delimited respectively by the two angular edges (38A, 38B) of the blade (36).

10. Device (10) according to claim 9, characterized in that the blade (36) comprises a free span face (55) formed on a tongue (56) extending in a slot (57) of the blade (36). ) interspersed angularly between the two free bearing surfaces (46A, 46B) delimited respectively by the two angular edges (38A, 38B) of the blade (36).

11. Device (10) according to any one of the preceding claims, characterized in that the hub (34) is extended radially by at least two adjacent peripheral blades (36) delimited respectively by two adjacent angular edges (38A, 38B) connected between them by a concave concave edge (43).

12. Device (10) according to any one of the preceding claims, characterized in that the hub (34) is extended radially by a plurality of blades (36) peripherals, the blades (36) connected to the first seal (30) alternating with the blades connected to the second lining (32).

13. Device (10) according to any one of the preceding claims, characterized in that at least one annular friction lining (30, 32) is delimited by outer and inner contours, such that the ratio of the diameter of the outer contour to the diameter of the inner contour is less than 1, 4, preferably less than 1.35.

14. Device (10) according to any one of the preceding claims, characterized in that at least one friction lining (30, 32) is bonded to the bonded surface face.

15. Device (10) according to any one of the preceding claims, characterized in that it comprises a wear compensating device.

16. Clutch for a motor vehicle, characterized in that it comprises a device (10) according to any one of the preceding claims.

A clutch for a motor vehicle according to claim 16 for coupling driving and driven rotary members, characterized in that the driven rotary member is rotatably connected to an input shaft of an automatic gearbox.