KR20170098176A - Annular friction lining for dry clutch - Google Patents

Abstract

The present invention relates to a friction lining for a dry clutch of a vehicle, which comprises: a friction surface (6); a friction material (2) fixated to a metal support (12); and at least one truncated cone-shaped groove (7, 8) provided in the friction material. In the friction lining, conicity of the truncated cone-shaped groove (7, 8) is 10-35%, and in particular, 17-30%.

Description

{ANNULAR FRICTION LINING FOR DRY CLUTCH FOR DRY CLUTCH}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annular friction lining of a single or double dry clutch, particularly for automobiles such as touring vehicles or industrial vehicles.

The clutch of an automobile generally comprises a friction disc with a friction lining on each side that is secured to a substantially common support and the support is secured to a splined hub that engages the input shaft of the gearbox. A torsional damper is generally inserted between a spline hub and a support or supports of a friction lining. Also, an advancing device is typically disposed between the two friction lining.

The friction disc comprises, on the one hand, a reaction plate directly or indirectly connected to the crankshaft of the car engine and, on the other hand, a pressure plate rotatably connected to the cover by being axially displaceable with respect to the pressure plate in a limited manner Is disposed between the pressure plate of the clutch mechanism including an axially driven cover, such as an annular diaphragm, coupled to the clutch hub and the reaction plate.

In the clutch connecting position, the lining of the friction disk is tightened between the reaction plate and the pressure plate, so that the rotational torque of the internal combustion engine is transmitted to the input shaft of the gearbox.

It is known to provide radial grooves in the friction lining to remove substantial contaminants (grease, oil, dust) that may be on the friction surface.

These grooves also help to evacuate all machining residues and, in particular, to prevent wear during commissioning. These grooves provide flexibility to the clutch disks to which the lining is fixed, thereby improving gap correction and minimizing noise and vibration of the clutch. But. These grooves weaken the friction lining and reduce the frictional resistance thereof. Further, such a groove does not improve the performance of the clutch in the face of a phenomenon called "fading ". When surface friction is prolonged, the lining undergoes considerable heating, which in turn substantially reduces the frictional coefficient of the surface. This is caused by the deterioration of the surface layer of the lining which acts as a lubricant between the integral part of the lining and the opposite surface of the friction material of the corresponding material. This deterioration is directly related to the energy released upon friction and the cooling quality of the lining.

On the one hand, a friction lining is known in the prior art for the purpose of restricting the reduction of this frictional coefficient by providing a grooved network of grooves having a straight, radial or inclined edge on the one hand and a circumferential edge on the other hand on the lining. These lining are evaluated to be satisfactory in terms of the stability of the coefficient of friction and the heat resistance under the standard conditions of use of the vehicle.

However, in harsh conditions of use, such as when a hill start is continuous, for example, when the hill start is continuous, the heat output to be emitted is substantially increased. The heat resistance of the lining lowers again. This causes a decrease in the coefficient of friction. As a result, in this harsh conditions of use, the engine torque is not delivered satisfactorily.

This problem also limits the use of these friction lining in cars that involve power-level transmissions such as industrial vehicles, touring vehicles.

The present invention is particularly directed to providing a simple, efficient and economical solution to this problem.

To this end, the invention relates to a friction lining for a dry clutch, in particular an automobile, comprising a frictional material comprising a frictional surface and fixed on a metal support, wherein at least one conical large groove is provided in the frictional material, Characterized in that the conicity is comprised between 10% and 35%, in particular between 17% and 30%.

When the energy released by the friction lining increases, especially under harsh operating conditions, these conical large grooves can satisfactorily cool the friction material, thereby limiting the degradation of the heat resistance of the friction material and thereby maintaining its engine torque transfer capability .

The conicity of the cone-shaped grooves can be defined with respect to the axis perpendicular to the friction surface.

The frictional surface may be one that is capable of contacting a corresponding material, such as a pressure plate or reaction plate, of the clutch to deliver engine torque.

According to a first variant of the invention, the cone-shaped grooves expand into a trumpet as they move away from the metal support. According to a second variant of the invention, the cone-shaped groove widens into a trumpet shape as it approaches the metal support.

The first modification permits the discharge of satisfactory dust and / or residue, while the second modification permits a maximum friction area.

The cone-shaped grooves may define a longitudinal axis, and the vertical section of the cone-

- a trapezoidal profile, and

An outer base belonging to a plane comprising the friction surface of the friction material, and

An inner base parallel to the outer base;

The continuous inner bases may define the bottom of the cone-shaped groove. The bottom portion may be parallel to the friction surface.

In a variant, the bottom of the groove can be inclined in a plane perpendicular to the longitudinal axis, and in particular can be bent.

In a first variant of the invention, the dimensions of the outer base may be comprised between 1.5 mm and 3 mm, while the dimensions of the inner base may be comprised between 0.5 mm and 2.5 mm. In a second variant of the invention, on the other hand, the dimensions of the outer base may be comprised between 0.5 mm and 2.5 mm, while the dimensions of the inner base may be comprised between 1.5 mm and 3 mm.

According to another aspect of the present invention,

The minimum thickness of the friction material between the bottom of the cone-shaped groove and the metal support,

- the ratio between the thickness of the friction material may be less than 0.2.

This small amount of material under the grooves can reduce the axial deflection over time which leads to a lack of planarity. This lack of planarity can cause the friction surface to be curtained or conical in shape.

This small amount of material also imparts flexibility to the friction material, allowing a good adaptation of the friction lining to the corresponding material of the clutch. Thus, the friction material can thus have a stable frictional force with temperature and can exhibit better heat dissipation (or heat exchange) in the grooves, indicating a higher number of starts at higher energies.

The thickness of the friction material can be defined as the dimension of the friction material along an axis perpendicular to this friction surface.

The friction material can be placed between the friction surface and the stationary surface facing the metal support.

This ratio may preferably be comprised between 0.08 and 0.14.

According to one aspect of the present invention,

The minimum thickness of the friction material between the bottom of the cone-shaped groove and the metal support,

The ratio between the thickness of the metal support may be less than one.

This ratio can allow the friction material to be adapted to the corresponding material of the clutch, especially if the thickness of the metal support is approximately 0.3 mm and the steel is easily deformable. In fact, friction materials having a ratio out of the above range may exhibit adhesion problems with the metal support, which may adversely affect the friction surface.

Thus, this ratio can ensure that the uniformity and planarity of the shape of the contact surface, whatever the thickness of the metal support and the temperature, is satisfactory.

This ratio may preferably be comprised between 0.2 and 0.8.

According to another aspect of the invention, the cone-shaped grooves extend substantially along a straight, circumferential or elliptical direction.

The friction material may include radially inner edges and radially outer edges. A straight conical large groove can be continuously extended between these two edges.

According to another aspect of the invention, the cone-shaped groove is tilted with respect to all radii that cut the groove. In the radially inner edge, the longitudinal axis may form an angle, in particular an angle of 15 degrees, which is comprised between 10 and 20 degrees, in particular a radius intersecting the longitudinal axis.

According to another aspect of the invention, a plurality of cone-shaped grooves is provided in the friction material. Some extend along the straight direction and others extend along the circumference or oval direction and these conical grooves can form a friction stud that forms a frictional surface in various places.

These cone-shaped grooves can maximize the area of the frictional surface, especially when these grooves flare as they approach the metal support.

According to another aspect of the invention, the thickness of the metal support is comprised between 0.1 and 1 mm, in particular between 0.3 and 0.6 mm.

According to another aspect of the invention, the thickness of the metallic material is comprised between 1.5 mm and 4 mm.

According to another aspect of the invention, the friction material can be glued or overmolded onto the metal support.

According to another aspect of the invention, the friction lining may be annular.

According to another aspect of the invention, the friction material comprises fibers, such as glass fibers, joined together by an organic matrix. The matrix may comprise a polymer such as a thermosetting resin, an elastomer such as rubber, and an organic or inorganic filler.

Different elements of the friction material can be pre-positioned to form the preform. Conical large grooves are obtained by removing the material according to the annulus of the resulting friction lining. In a variant, the final form of the friction material can be obtained by injection in molds forming molds corresponding to annular and cone-shaped groove shapes.

The invention also relates to the use of a friction lining according to the invention in a wet clutch for an automobile. Such a clutch may include a lining having some or all of the features described above for lining in a dry clutch.

Finally, the present invention relates to a clutch disc for a motor vehicle in particular, characterized in that it comprises at least one friction lining as described above.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and other details, features and advantages of the invention will become apparent from the teaching of the detailed description which follows, by way of non-limiting example, with reference to the accompanying drawings, in which:
1 is a perspective view of an example of a friction lining according to the present invention,
2A and 2B are a detailed view of a cone-shaped groove according to a first modification example and a second modification example of the present invention, respectively;
3 is a detailed view of a cone-shaped groove according to another example of the first modification,
Figures 4A, 4B, 5A and 5B are graphs comparing the performance of friction linings within the scope of the present invention and outside the scope of the present invention,
6 is a chart showing the reduction in axial strain of an example of a friction lining according to the present invention at different conditions of use.

Fig. 1 shows an example of an annular friction lining 1 for a dry clutch. The lining 1 comprises a friction material 2 fixed on a metal support, which will be described later. The friction material 2 is capable of contacting the radially inner edge 3 and the outer edge 4, the fixing surface 5 for the metal support, and the corresponding material, such as the pressure plate or reaction plate of the clutch, And transmits the engine torque including the friction surface (6).

In the disclosed embodiment, the material 2 is bonded or overmolded onto a metal support.

In the disclosed embodiment, a plurality of conical large grooves 7, 8 are provided in the friction material, a portion 7 extends in a linear direction and the other portion 8 extends in the circumferential direction, And the surfaces of these studs 9, which are the furthest away from the metal support, define the friction surface 6 .

On the other hand, the linear conical large grooves 7 extend between the two radial edges of the interior 3 and exterior 4 of the material 2 and all the grooves provided in the material 2 are conical.

The longitudinal axis of each linear conical large groove 7 forms an angle of 15 degrees with the radius intersecting the longitudinal axis at the radially inner edge 3.

In the disclosed embodiment, the material 2 may comprise glass fibers connected together by an organic matrix. The matrix may include thermosetting resins, elastomers, rubbers and organic or inorganic fillers. Different elements of the friction material can be pre-positioned to form the preform.

Conical large grooves are obtained by removing the material according to the annulus of the resulting friction lining.

In a variant, the material (2) can be obtained by injection in a mold of the mold corresponding to the shape of the annular and conical grooves.

Figures 2a and 2b show the vertical sections of the cone-shaped grooves 7, 8, respectively, with respect to the longitudinal axis of the grooves shown.

In Fig. 2A, according to the first modification, the conical large grooves 7, 8 extend in a trumpet shape away from the metal support 12, while in Fig. 2b, according to the second variant, the conical large grooves 7 , 8 are opened in a trumpet shape close to the metal support 12.

According to two variants, the cone-shaped grooves 7, 8 have an outer base 14 which has a trapezoidal profile and belongs to a plane comprising the friction surface 6 and an inner base 15 which is parallel to the outer base . Wherein the inner base 15 defines the bottom 16 of the cone-shaped groove, which is parallel to the friction surface 6. In a variant, the bottom of the groove can be inclined in a plane perpendicular to the longitudinal axis, and in particular can be bent.

According to the embodiment of Figures 2a and 2b, the conicity of the cone-shaped grooves 7, 8 is comprised between 10% and 35%, in particular between 17% and 30%, the conicity being perpendicular to the friction surface Axis.

Finally, in the embodiment disclosed in Figures 2a and 2b, the cone-shaped grooves 7, 8 extend to the metal support 12 but the friction studs 9 are separate from each other, so that the material 2 is discontinuous . However, the amount of material 2 under the cone-shaped grooves 7, 8 can be reduced so as not to touch the steel surface and to not transmit shear stress at the adhesive joint at the interface between the material 2 and the metal support .

In an embodiment of the first variant disclosed in Figure 2a, the diameter of the outer base is comprised between 1.5 mm and 3 mm, while the diameter of the inner base is comprised between 0.5 mm and 2.5 mm.

2B, the diameter of the outer base 14 is comprised between 0.5 mm and 2.5 mm, while the diameter of the inner base 15 is comprised between 1.5 mm and 3 mm. These dimensions are calculated in a vertical plane as shown in Figs. 2A and 2B.

The material 2 with the cone-shaped grooves disclosed in Figures 2a and 2b can be produced by other methods for the placement of cone-shaped grooves extending to the metal support without fear of weakening the adhesive joints.

The material (2) of Figs. 2A and 2B can be obtained by a process different from that already mentioned. This process, particularly,

- fabricating a material (2) comprising a conical large groove which is only open to a fixed surface,

Fixing the rubbing body on the metal support by adhesion of the fixing surface,

Machining the friction surface opposite to the fixing surface until the groove reaches the second surface of the friction body.

The cone-shaped grooves 7 and 8 shown in Fig. 3 are another embodiment of the first modification. In this embodiment, the thickness D ₁ of the material defined between the friction surface 6 and the fixing surface 5 is comprised between 1.5 mm and 4 mm and the thickness D ₂ of the metal support is between 0.1 mm and 1 mm, in particular between 0.3 mm and 0.6 mm.

In the embodiment disclosed in Figure 3,

A minimum thickness (D ₃ ) of the material between the bottom of the cone-shaped groove and the metal support,

- the ratio (R ₁₎ between the thickness (D ₁₎ of the friction material is less than 0.2.

Subsequently, in this embodiment,

- the minimum thickness (D ₃ ) of the material (2) between the bottom (16) of the cone-shaped groove and the metal support (12)

- the ratio (R ₂ ) between the thickness (D ₂ ) of the metal support is less than one.

In the disclosed embodiment, the thickness of the friction material D ₁ is defined as the dimension of the material 2 along the vertical axis of the friction surface 6.

In the embodiment disclosed in Figure 3, the conicity expressed as a percentage is as follows:

(Dimension of the outer base 14 - Dimension of the inner base 15 | / (D1 - D3)} * 100

Figs. 4A, 4B, 5A and 5B show comparative test results of the lining 1 within the scope of the invention and the lining outside the scope of the invention.

These tests were conducted on a test bench using a manual gearbox. To simulate harsh conditions of use, particularly a hill start, an energy release of approximately 364 J / cm ² is imposed on the friction lining (1). The lining 1 used for these tests has an inner diameter of approximately 137 mm and an outer diameter of approximately 200 mm. The dimensions of the outer base of the cone-shaped grooves exceed 1.5 mm.

During these tests, each lining was given a start-up sequence and the number of starts for which the lining delivered satisfactory engine torque was recorded.

Under test conditions, the lining satisfactorily delivers torque when there is no slip and the friction coefficient remains above 0.2 at constant body weight and flat load conditions.

The structural characteristics of the lining used in the tests outside the scope of the present invention are shown in Table 1, and the lining (1) falling within the scope of the present invention used for the tests is shown in Table 2.

R ₁ R ₂ Connie City Lining 1 0.27 1.75 37 Lining 2 0.27 1.75 37 Lining 3 0.27 1.75 37 Lining 4 0.27 1.75 37 Lining 5 0.28 2.5 26 Lining 6 0.04 0.25 0 Lining 7 0.04 0.25 0

R ₁ R ₂ Connie City Lining 8 0.04 0.25 21 Lining 9 0.12 0.75 27 Lining 10 0.12 0.75 27 Lining 11 0.02 0.13 17

The lining 11 is opened in a trumpet shape as it approaches the metal support 12. [

Test results of the lining of Table 1 are shown in Figs. 4A and 4B, and test results of the lining of Table 2 are shown in Figs. 5A and 5B. The number of starts in the satisfactory torque delivery state shown in accordance with R ₁ (Figs. 4A and 5A) or R ₂ (Figs. 4B and 5B) can be found in the coordinates.

It is confirmed that the lining of Table 2 is particularly advantageous and can double the number of starts in harsh conditions as compared to the lining of Table 1.

The lining 1 according to the embodiment can cause the axial deformability causing planar defects to decrease with time.

The lining (initial state) at 25 占 폚, followed by a lining at 140 占 폚 for 4 hours, and finally a lining at 40 占 폚 and 90% humidity for 24 hours (A, B and C ).

At the end of these steps, a load of 1000 N was applied to these lining and this load was gradually released to 20 N.

Each of the rectangles A, B, C represents the percentage of displacement reduction in the plane including the friction surface between the friction lining according to the invention and the test lining outside the scope of the invention.

The axial displacement is reduced by at least 65%, at least 40% and at least 50% for tests A, B and C.

In each of the tests shown, examples of lining within the scope of the invention and examples of lining outside the scope of the invention differ only in the form of the groove. Their internal composition, their metallic supports and their number of grooves are the same to emphasize the influence of the shape of the grooves according to the invention.

The present invention is not limited to the disclosed embodiments.

Claims (11)

A friction material (2) comprising a friction surface (6) and fixed on a metal support (12), wherein at least one conical large groove (7, 8) is provided on said friction material, In the friction lining (1)
Characterized in that the conicity of the conical large grooves (7, 8) is comprised between 10% and 35%, in particular between 17% and 30%
Friction lining. The method according to claim 1,
Characterized in that the cone-shaped grooves (7, 8) flare away from the metal support (12)
Friction lining. The method according to claim 1,
Characterized in that the cone-shaped grooves (7, 8) are flared as they approach the metal support (12)
Friction lining. 3. The method of claim 2,
The conical large-scale grooves (7, 8) define a longitudinal axis, and the vertical section of the conical large-
Trapezoidal profile, and
An outer base (14) belonging to a plane comprising the friction surface (6) of said friction material, and
And an inner base (15) parallel to the outer base,
Characterized in that the dimension of the outer base (14) is comprised between 1.5 mm and 3 mm and the dimension of the inner base (15) is comprised between 0.5 mm and 2.5 mm
Friction lining. The method of claim 3,
The conical large-scale grooves (7, 8) define a longitudinal axis, and the vertical section of the conical large-
Trapezoidal profile, and
An outer base (14) belonging to a plane comprising the friction surface (6) of said friction material, and
And an inner base (15) parallel to the outer base,
Characterized in that the dimension of the outer base (14) is comprised between 0.5 mm and 2.5 mm and the dimension of the inner base (15) is comprised between 1.5 mm and 3 mm
Friction lining. 6. The method according to any one of claims 1 to 5,
The thickness (D ₃ ) of the frictional material between the bottom portion (16) of the cone-shaped groove and the metal support,
Characterized in that the ratio (R ₁ ) between the thickness (D ₁ ) of said friction material is less than 0.2
Friction lining. 7. The method according to any one of claims 1 to 6,
A minimum thickness (D ₃ ) of the frictional material between the bottom portion (16) of the cone-shaped groove and the metal support,
And the ratio (R ₂ ) between the thickness (D ₂ ) of the metal support is less than 1
Friction lining. 8. The method according to any one of claims 1 to 7,
Characterized in that the conical large grooves (7, 8) extend substantially along a straight, circumferential or elliptical direction
Friction lining. 9. The method according to any one of claims 1 to 8,
A plurality of conical large grooves 7 and 8 are provided in the friction material and a part 7 extends in the linear direction and the other part 8 extends in the circumferential or elliptical direction, 8) are formed to form the friction studs 9
Friction lining. 10. The method according to any one of claims 1 to 9,
Characterized in that the thickness of the metal support (12) is comprised between 0.1 mm and 1 mm, in particular between 0.3 mm and 0.6 mm
Friction lining. Characterized in that it comprises at least one friction lining (1) according to any one of the claims 1 to 10
Clutch discs especially for automobiles.

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