Friction plate and wet multi-plate clutch including friction plate

Abstract

To provide a friction plate capable of reducing drag torque and preventing sudden biting of a clutch.SOLUTION: The frictional plate 10 has a plurality of frictional materials 12 on a substantially annular core plate 3, the frictional plate 10 is provided with a plurality of oil passages 10i communicating between an inner peripheral edge 10e and an outer peripheral edge 10g of the frictional plate 10, the frictional material 12 is provided with an oil groove 10i having one end opened to the inner peripheral edge 12g of the frictional plate 10 and the other end closed between the inner and outer peripheral edges, and the oil groove 12g has a shape narrowing in a circumferential direction of the frictional plate 10 from the inner peripheral edge 10i toward the outer peripheral edge 10e of the frictional plate 10. The 10g of the oil path and the 12g of the oil groove are inclined along the rotating direction of the frictional plate 10.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a friction plate and a wet multi-plate clutch equipped with the friction plate. [Background technology]

[0002] Generally, in a wet multi-plate clutch, friction plates and separator plates are arranged alternately between the clutch or brake drum and hub, and the clutch is engaged and disengaged by pressing and releasing the clutch piston. Furthermore, in order to reduce power loss, wet multi-plate clutches used in automatic transmissions (ATs) are often designed to allow lubricating oil to easily escape from the inner periphery of the friction plates to the outer periphery, thereby reducing drag torque between the friction plates and separator plates.

[0003] Patent Document 1 discloses a friction plate having an oil passage that communicates from the inner peripheral edge to the outer peripheral edge of a friction material attached to the friction plate, and an oil groove that opens to the inner peripheral edge and has an opening end halfway along the friction surface, with both the oil passage and the oil groove gradually narrowing from the inner peripheral edge to the outer peripheral edge.Patent Document 2 discloses a friction plate having a configuration in which a friction material fixed to an externally toothed disc has a groove that communicates from the inner diameter part to the outer diameter part and is inclined in accordance with the rotation direction of the internally toothed disc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-76759 [Patent Document 2] Japanese Patent Application Publication No. 10-169681 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, oil grooves and oil passages are provided to reduce drag torque and improve friction characteristics. In Patent Document 2, grooves are provided that are inclined in the direction of rotation to improve the removal of lubricating oil and reduce drag torque. However, in recent years, there has been an increasing demand for reducing drag torque and preventing sudden clutch bite in the initial stage of frictional engagement in order to reduce power loss when the clutch is disengaged, even in automatic transmissions.

[0006] An object of the present invention is to provide a friction plate that can reduce drag torque and prevent sudden clutch bite at the initial stage of frictional engagement. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a friction plate having a plurality of friction materials in a substantially annular core plate, wherein the friction plate is provided with a plurality of first oil grooves that connect the inner peripheral edge and the outer peripheral edge of the friction plate, and the friction material is provided with a second oil groove, one end of which opens to the inner peripheral edge of the friction plate and the other end of which is closed between the inner and outer peripheral edges, the second oil groove has a shape in which its width in the circumferential direction of the friction plate narrows from the inner peripheral edge toward the outer peripheral edge of the friction plate, and the first oil groove and the second oil groove are inclined in accordance with the rotation direction of the friction plate. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a friction plate that can reduce drag torque and prevent sudden clutch bite at the initial stage of frictional engagement. [Brief explanation of the drawings]

[0009] [Figure 1]1A is a partial axial cross-sectional view of a wet multi-plate clutch 100 according to an embodiment of the present invention, which is provided with the friction plates 10. FIG. 1B is a partial axial cross-sectional view of a wet multi-plate clutch 200 according to another embodiment of the present invention, which is provided with the friction plates 10. [Figure 2] 1A is a front view of a friction plate 10 of the present invention, FIG. 1B is a side view of a friction plate 10 of the present invention, and FIG. 1C is a front view of one friction material 12. [Figure 3] 1A and 1B are partial enlarged views of a friction plate 10 of the present invention, showing an enlarged view of a friction material 12 attached to a core plate 3 of the friction plate 10. FIG. [Figure 4] 2 is a schematic diagram showing the flow of lubricating oil L in the friction plate 10 of the present invention. FIG. [Figure 5] 1 is analytical data showing the effect of the friction plate 10 of the present invention.

[0010] (Embodiment) The present invention will be described in detail below with reference to the accompanying drawings. In the drawings, the same parts are designated by the same reference numerals and their explanations are omitted. Fig. 1(A) is a partial axial cross-sectional view of a wet multi-plate clutch 100 according to an embodiment of the present invention, which is equipped with a friction plate 10.

[0011] The wet multi-plate clutch 100 is composed of a substantially cylindrical clutch case 1 that is open at one end in the axial direction, a hub 4 that is arranged on the inner periphery of the clutch case 1 and rotates coaxially relative to the clutch case 1, annular separator plates 2 that are arranged axially movably on splines 8 provided on the inner periphery of the clutch case 1, and annular friction plates 10 that are arranged axially alternately with the separator plates 2 on splines 5 provided on the outer periphery of the hub 4 and have friction material 12 adhered to annular core plates 3. There are a plurality of separator plates 2 and a plurality of friction plates 10.

[0012] The clutch case 1 has a plurality of through holes 14 on its outer periphery. Lubricating oil L is supplied from the inner diameter side and lubricates the clutch parts, then moves to the outer diameter side by centrifugal force, passes through the through holes 14, and is discharged to the outside. It goes without saying that the present invention can also be applied to a wet multi-plate clutch having a clutch case 1 that is not provided with through holes 14.

[0013] The wet multi-plate clutch 100 includes a piston 6 that presses and fastens the separator plates 2 and friction plates 10 to bring the wet multi-plate clutch 100 into an engaged state, and a backing plate 7 provided on the inner periphery of the clutch case 1 and a retaining ring 17 that holds the backing plate 7 in place to hold the separator plates 2 and friction plates 10 in a fixed state at one end in the axial direction.

[0014] As shown in Figure 1(A), the piston 6 is arranged so as to be axially slidable within the closed end of the clutch case 1. An O-ring 9 is interposed between the outer peripheral surface of the piston 6 and the inner surface of the clutch case 1. A seal member (not shown) is also interposed between the inner peripheral surface of the piston 6 and the outer peripheral surface of the cylindrical portion (not shown) of the clutch case 1. Therefore, an oil-tight hydraulic chamber 11 is defined between the inner surface of the closed end of the clutch case 1 and the piston 6.

[0015] Friction plates 10 are held axially slidably on the hub 4, and friction materials 12 having a predetermined friction coefficient are fixed to both sides of the friction plates 10. However, friction materials 12 may be provided on only one side of the friction plates 10. In addition, the hub 4 is provided with a lubricating oil supply port 13 penetrating in the radial direction, and lubricating oil L is supplied from the inner diameter side to the outer diameter side of the wet multi-plate clutch 100.

[0016] Figure 1(B) is a partial axial cross-sectional view of a wet multi-plate clutch 200 according to another embodiment, equipped with friction plates 10 of the present invention. The basic configuration is the same as that of the wet multi-plate clutch 100 shown in Figure 1(A), so only the differences will be explained. In Figure 1(B), the spline engagement relationship between the friction plates 10 and the separator plates 2 is reversed compared to Figure 1(A). In the wet multi-plate clutch 100 of the configuration shown in Figure 1(B), the friction plates 10 engage with splines 8 on the clutch case 1, and the separator plates 2 engage with splines 5 on the hub 4. The backing plate 7 and the retaining ring 17 that holds it are also attached to the hub 4 side.

[0017] The wet multi-plate clutch 100 configured as described above engages and disengages the clutch as follows: Figure 1(A) shows the clutch disengaged state, in which the separator plate 2 and the friction plates 10 are separated and not in contact with each other. In the disengaged state, the piston 6 abuts against the closed end of the clutch case 1 due to the biasing force of a return spring (not shown).

[0018] To engage the clutch in this state, hydraulic pressure is supplied to the hydraulic chamber 11 defined between the piston 6 and the clutch case 1. As the hydraulic pressure increases, the piston 6 moves axially to the right in FIG. 1(A) against the biasing force of a return spring (not shown), bringing the separator plate 2 and the friction plate 10 into close contact with each other. This engages the clutch.

[0019] To release the clutch again after it has been engaged, the hydraulic pressure in the hydraulic chamber 11 is released. When the hydraulic pressure is released, the piston 6 moves by the biasing force of a return spring (not shown) to a position where it abuts against the closed end of the clutch case 1. In other words, the clutch is released. The same applies to the wet multi-plate clutch 200.

[0020] (Example) In recent years, there has been an increasing demand for low fuel consumption in automobiles, and in order to reduce power loss when the clutch is disengaged, there is an increasing demand for a reduction in drag torque and for preventing sudden clutch bite at the initial stage of friction engagement in automatic transmissions. A friction plate 10 according to an embodiment of the present invention that meets the above requirements will now be described in detail.

[0021] FIG. 2(A) is a front view of a friction plate 10 of the present invention, FIG. 2(B) is a side view of the friction plate 10, and FIG. 2(C) is a front view of one friction material 12. The friction plate 10 is configured by fixing a plurality of friction materials 12 shown in FIG. 2(C) in a substantially annular shape onto a substantially annular core plate 3. Spline teeth 10s are formed on the inner periphery of the friction plate 10 for spline engagement with a mating torque transmission component. The friction plate 10 is provided with a plurality of oil passages 10g (first oil grooves) that communicate between the inner peripheral edge 10i and the outer peripheral edge 10e of the friction plate 10. A plurality of friction materials 12 are fixed to the friction plate 10 so that an oil passage 10g is formed between each friction material 12 and an adjacent friction material 12. The circumferential width of the oil passage 10g is substantially constant from the inner peripheral edge 10i to the outer peripheral edge 10e. An oil groove 12g (second oil groove) is provided on the surface of the friction material 12. One end of the oil groove 12g opens to the inner peripheral edge 10i of the friction plate 10, and the other end is closed between the inner and outer peripheral edges. The oil groove 12g has a shape in which the width in the circumferential direction of the friction plate 10 narrows from the inner peripheral edge 10i of the friction plate 10 toward the outer peripheral edge 10e.

[0022] 3A and 3B are partial enlarged views of the friction plate 10 to show the friction material 12 attached to the core plate 3 of the friction plate 10 of the present invention. The oil groove 12g has an opening at the inner circumferential edge 10i and a closed portion 12c on the friction surface. The friction materials 12 with the oil grooves 12g are arranged on the core plate 3 of the friction plate 10 at approximately equal intervals in the circumferential direction of the friction plate 10 so as to form oil passages 10g, and are fixed with an adhesive. A plurality of friction materials 12 are provided, and the oil groove 12g is provided at approximately the center of each friction material 12 in the circumferential direction. The oil grooves 12g and the oil passages 10g are arranged alternately in the circumferential direction. As shown in FIG. 3A, the oil passages 10g and the oil grooves 12g are both inclined in the rotational direction RD of the friction plate 10.

[0023] Here, the configuration that "the oil passages 10g and the oil grooves 12g are inclined following the rotational direction RD of the clutch" refers to a direction that does not impede the movement of the lubricating oil L, which is given movement by the rotation of the clutch, when it moves from the inside to the outside due to centrifugal force. In other words, the center lines CL of the oil passages 10g and the oil grooves 12g in the circumferential direction are inclined at an inclination angle θ (angle) in the opposite direction to the rotational direction RD with respect to the normal line NL of the inner peripheral edge 10i of the friction plate 10.

[0024] As shown in FIG. 3B, the oil groove 12g is located approximately in the circumferential center between two adjacent oil passages 10g. The oil groove 12g extends obliquely from approximately the circumferential center of the friction material 12 and terminates at a closed portion 12c between the inner and outer peripheral edges. The closed portion 12c is not pointed but has an approximately semicircular arc. The width of the closed portion 12c (the diameter of the approximately semicircle) is shorter than the width of the opening of the oil groove 12g (GL-GR). The oil groove 12g is gradually narrowed from the inner peripheral edge 10i to the outer peripheral edge 10e. That is, the oil groove 12g is defined by two tapered surfaces that open toward the inner peripheral edge 10i of the friction plate 10 at a predetermined opening angle α. The opening angle α of the oil groove 12g is set to a predetermined angle.

[0025] When the radius of the outer peripheral edge 10e of the friction plate 10 is defined as the outer radius Fe and the radius of the inner peripheral edge 10i of the friction plate 10 is defined as the inner radius Fi, it is preferable that the center T of the arc portion constituting part of the closing portion 12c of the oil groove 12g is positioned in the radial direction of the friction plate 10 so that the value of the constant R in the following formula is in the range of 0.2 to 0.8. T=Fi+(Fe-Fi)×R 2≦R≦0.8 That is, it is preferable that the radial length of the oil groove 12g is approximately 20% to 80% of the radial width (Fe-Fi) of the friction plate 10.

[0026] Next, we will explain the position of the closed portion 12c (arc portion) of the oil groove 12g in the circumferential direction of the friction plate 10. When an arc AT, whose radius is the distance from the center O of the friction plate 10 to the center T of the arc portion, intersects with the oil passage 10g on the left side of the drawing at an intersection point TL and with the oil passage 10g on the right side of the drawing at an intersection point TR, the closed portion 12c is preferably located near a point that approximately bisects a straight line L connecting the intersection points TL and TR.

[0027] It is preferable that the distance (G1-GL) from the intersection G1 of the inner peripheral edge 10i of the friction plate 10 and the left-side oil passage 10g to the intersection GL of the inner peripheral edge 10i of the friction plate 10 and the oil groove 12g on the left side of the drawing, and the distance (G2-GR) from the intersection G2 of the inner peripheral edge 10i of the friction plate 10 and the right-side oil passage 10g to the intersection GR of the inner peripheral edge 10i of the friction plate 10 and the oil groove 12g on the right side of the drawing, are 1 mm or more.

[0028] 4 is a schematic diagram showing the flow of lubricating oil L in the friction plate 10 of the present invention. The lubricating oil L flows into the oil passage 10g and the oil groove 12g. The lubricating oil L1 that flows into the oil passage 10g flows toward the outer peripheral edge 10e. On the other hand, the lubricating oil L2 that flows into the oil groove 12g passes over the oil groove 12g and becomes lubricating oil L3. The friction plate 10 of the present invention imparts an inclination angle θ to the oil groove 12g that extends from the inner peripheral edge 10i side of the friction plate 10 to the outer peripheral edge 10e side and terminates between the inner and outer peripheral edges, and limits the rotational direction RD, thereby increasing the amount of lubricating oil L2 that flows in. As a result, the force separating the friction plate 10 and the separator plate 2 increases, making it possible to significantly reduce the drag torque.

[0029] Furthermore, the lubricating oil L3 overflowing from the oil groove 12g runs onto the friction surface of the friction material 12, preventing the clutch from suddenly biting at the initial stage of engagement. The dischargeability of the inflowing lubricating oil L2 is dramatically improved.

[0030] FIG. 5 shows analytical data showing the effect of the friction plate 10 of the present invention. The horizontal axis represents the inclination angle θ (deg) of the oil passage 10g and the oil groove 12g, and the vertical axis represents the separation force F (N). The analytical data shows that an effective separation force F can be obtained when the inclination angle θ is between 20 and 50 degrees. More preferably, the largest separation force F can be obtained when the inclination angle θ is 30 degrees. Note that the separation force F in the conventional example is obtained when the inclination angle θ is 0 degrees.

[0031] The above describes an embodiment in which the friction plate 10 is configured by fixing a plurality of friction materials 12 in an annular shape to a substantially annular core plate 3. However, the friction material 12 may be substantially annular, and oil passages 10g and oil grooves 12g may be formed in the friction material 12 alternately at predetermined intervals in the circumferential direction. The friction plate 10 may also be configured by attaching the substantially annular friction material 12 to the core plate 3 of the friction plate 10 approximately coaxially.

[0032] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the present invention. [Explanation of symbols]

[0033] 3 Core Plate 10 Friction Plate 10g Oil passage (first oil groove) 10i inner rim 10e outer edge 12 Friction material 12g Oil groove (second oil groove) 100 Wet multi-plate clutch CL center line NL normal θ Inclination angle (angle) RD rotation direction

Claims

1. A friction plate in which a friction material is fixed to a substantially annular core plate, the friction plate is provided with a plurality of first oil grooves that communicate with an inner peripheral edge and an outer peripheral edge of the friction plate; the friction material is provided with a second oil groove, one end of which opens to the inner peripheral edge of the friction plate and the other end of which is closed between the inner and outer peripheral edges, the second oil groove has a shape in which the width in the circumferential direction of the friction plate narrows from the inner peripheral edge toward the outer peripheral edge of the friction plate, The friction plate, wherein the first oil groove and the second oil groove are inclined in accordance with the rotation direction of the friction plate.

2. 2. The friction plate according to claim 1, wherein center lines of the first oil groove and the second oil groove in the circumferential direction are inclined at an angle opposite to the rotation direction with respect to a normal to the inner peripheral edge of the friction plate.

3. 3. The friction plate according to claim 2, wherein the angle is in the range of 20 to 50 degrees.

4. 3. The friction plate according to claim 2, wherein the angle is 30 degrees.

5. 2. The friction plate according to claim 1, wherein the first oil grooves and the second oil grooves are alternately provided in the circumferential direction.

6. 2. The friction plate according to claim 1, wherein the width of the first oil groove in the circumferential direction is substantially constant from the inner circumferential edge to the outer circumferential edge.

7. 2. The friction plate according to claim 1, wherein the second oil groove is provided at a substantially central position in the circumferential direction between two adjacent first oil grooves.

8. 2. The friction plate according to claim 1, wherein the other end of the second oil groove terminates at a position within a range of approximately 20% to 80% of the radial width of the friction plate.

9. 2. The friction plate according to claim 1, wherein the plurality of friction materials are attached to the core plate in a substantially annular shape at substantially equal intervals at predetermined intervals so as to form the first oil groove.

10. The friction material has a substantially annular shape, The first oil grooves and the second oil grooves are alternately formed in the friction material at predetermined intervals in the circumferential direction, 2. The friction plate according to claim 1, wherein the friction material is attached to the friction plate substantially coaxially.

11. A wet multi-plate clutch comprising: the friction plates according to any one of claims 1 to 10; and separator plates arranged alternately with the friction plates in the axial direction.

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