JP2018185049A - Friction plate and wet multiple disc clutch including friction plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction plate of a wet multiple disc clutch, capable of reducing dragging torque, securing a frictional area and preventing deterioration of heat durability.SOLUTION: A friction plate 3 is formed by annularly fixing a plurality of friction material segments 12 to a roughly annular core plate 20, and on a surface of the friction material segment 12, a plurality of fine grooves is formed. The friction plate is characterized in that the fine groove has a width of 10-1000 μm, and a depth of 10-300 μm, and the total area of the fine grooves is 1-20% of an area of a friction surface 25 of the friction material segment 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a friction plate used for a clutch and a brake of an automatic transmission in an automobile, and a wet multi-plate clutch provided with a friction plate.

  In general, a wet type multi-plate clutch in an automatic transmission has a friction plate (friction plate) and a separator plate arranged alternately between a clutch or brake drum and a hub. Join and release are performed.

  Such a wet multi-plate clutch generates drag torque that causes power loss through the lubricating oil when the clutch is released, and these can be reduced to an automatic transmission in response to recent environmental regulations and demands for lower fuel consumption in automobiles. It is an important issue.

  In the friction plate of the wet multi-plate clutch, as a conventional method for reducing the drag torque, for example, a forming groove is provided on the friction material surface of the friction plate described in Patent Document 1 or the friction of the friction plate described in Patent Document 2 By using the segment shape for the material and passing through the oil path between the friction materials, the effect of each oil discharge (separation etc.) can be used to reduce the drag torque in the constant speed range of the automatic transmission Has been shown.

  In the above-mentioned variable speed rotation region, there is a high demand for reducing the drag torque, particularly in the low rotation region, and the conventional measures have the following problems.

  When forming grooves are used on the friction material surface of the friction plate, the grooves cause a separation effect between the plates by draining and using the oil, and these show the effect of reducing the drag torque of the friction plate. However, increasing the area of the oil discharge groove in order to obtain a higher reduction effect decreases the friction area of the friction plate, and there is a problem that the heat durability is lowered.

  When the segment shape is used for the friction material, not only the separation effect between the plates, but also the oil drainage and the decrease in the viscosity (flow) resistance after the discharge can be remarkably improved, and the drag torque reduction is dramatically improved. However, using a segment shape to improve oil drainability in order to achieve a higher reduction effect prevents a stable oil film from lubricating oil on the friction material surface, which causes fluid shear resistance and hinders drag torque reduction. It will be.

  On the other hand, as described in Patent Document 3, it has been proposed to reduce drag torque by forming a large number of fine grooves on the surface of the friction material and forming an air layer on the surface. They only present one proposal for the effect of reducing drag torque in a lubrication environment, and do not mention the effect of reducing the speed change region.

  Prior art document information related to the invention of this application includes the following.

Japanese Patent Laying-Open No. 2005-077659 JP 2008-180314 A JP 2010-223342 A

  Therefore, in view of the above problems, the object of the present invention is to provide a fine groove that suppresses the reduction of the friction material area in the friction plate of the wet multi-plate clutch, thereby reducing the drag torque in the low rotation region, and heat resistance and durability. It is to provide a friction plate that does not deteriorate the properties.

In order to achieve the above object, the friction plate of the present invention comprises:
A friction plate formed by fixing a plurality of friction material segments in an annular shape to a substantially annular core plate,
It is characterized in that a reduction in drag torque in the low rotation region can be provided by providing fine grooves on the surface of the friction material segment.

  According to the present invention, the following effects can be obtained.

  By forming a fine groove on the surface of the friction material segment, a surface oil film between the friction plate and the separator plate can be secured, so that drag torque can be reduced by reducing fluid shear resistance. In particular, it is effective for reducing drag torque in a low rotation range of 1000 rpm.

  By setting the width of the fine groove to about 10 μm to 1000 μm, there is little influence on the reduction of the friction area on the friction surface of the friction material segment, so that sufficient heat resistance can be ensured.

FIG. 1 is a partial sectional view in the axial direction of a wet multi-plate clutch provided with a friction plate of the present invention. 1 is a partial front view of a friction plate showing a first embodiment of the present invention. It is a front view which shows the friction material segment used for the friction board of 1st Example of this invention. It is a front view of the friction material segment used for the friction board of 2nd Example of this invention. It is a front view of the friction material segment used for the friction board of 3rd Example of this invention. It is a graph which shows the effect of each Example of this invention, and a comparative example (conventional example).

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same parts are denoted by the same reference numerals.

  FIG. 1 is a partial cross-sectional view in the axial direction of a wet multi-plate clutch 10 having a friction plate of the present invention. The friction plate of each Example of this invention is applicable.

  The wet multi-plate clutch 10 includes a substantially cylindrical clutch drum 1 that is opened at one end in the axial direction, a hub 4 that is disposed on the inner periphery of the clutch drum 1 and relatively rotates on the same axis, and an inner periphery of the clutch drum 1. An annular separator plate 2 disposed on a spline 8 provided on the outer periphery of the hub 4 and an axially movable separator plate 2 disposed on the outer periphery of the hub 4 are disposed alternately with the separator plate 2 in the axial direction. It comprises an annular friction plate 3 having a friction surface fixed with an adhesive or the like. The separator plate 2 includes a spline portion 2 a that engages with the spline 8, and the friction plate 3 includes a spline portion 3 a that engages with the spline 5. A plurality of friction plates 3 and separator plates 2 are provided.

  The wet multi-plate clutch 10 is configured to press and fasten the separator plate 2 and the friction plate 3, and to hold the separator plate 2 and the friction plate 3 in a fixed state at one end in the axial direction. And a retaining ring 17 that holds the backing plate 7.

  As shown in FIG. 1, the piston 6 is slidably disposed in the axial direction within the closed end of the clutch drum 1. An O-ring 9 is interposed between the outer peripheral surface of the piston 6 and the inner surface of the clutch drum 1. Further, a seal member (not shown) is also interposed between the inner peripheral surface of the piston 6 and the outer peripheral surface of the inner peripheral cylindrical portion (not shown) of the clutch drum 1. Therefore, an oil tight hydraulic chamber 11 is defined between the inner surface of the closed end of the clutch drum 1 and the piston 6.

  The friction plate 3 slidably held in the axial direction by the hub 4 is fixed with friction material segments 12 and 13 having a predetermined friction coefficient on both surfaces thereof. However, the friction material segments 12 and 13 may be provided only on one side of the friction plate 3. The hub 4 is provided with a lubricating oil supply port 15 penetrating in the radial direction, and the lubricating oil is supplied from the inner diameter side to the outer diameter side of the wet multi-plate clutch 10 through the lubricating oil supply port 15. .

  The wet multi-plate clutch 10 configured as described above engages (fastens) and releases the clutch as follows. The state of FIG. 1 shows a clutch release state, and the separator plate 2 and the friction plate 3 are separated from each other. In the released state, the piston 6 is in contact with the closed end side of the clutch drum 1 by the biasing force of a return spring (not shown).

  In order to engage the wet multi-plate clutch 10 in this state, hydraulic pressure is supplied to the hydraulic chamber 11 defined between the piston 6 and the clutch drum 1. As the hydraulic pressure rises, the piston 6 moves to the right in the axial direction in FIG. 1 against the urging force of a return spring (not shown) to bring the separator plate 2 and the friction plate 3 into close contact. As a result, the wet multi-plate clutch 10 is engaged.

  To release the wet multi-plate clutch 10 again after the wet multi-plate clutch 10 is engaged, the hydraulic pressure in the hydraulic chamber 11 is released. When the hydraulic pressure is released, the piston 6 moves to a position where it abuts against the closed end of the clutch case 1 by the urging force of a return spring (not shown). That is, the wet multi-plate clutch 10 is released.

(First embodiment)
FIG. 2 is a partial front view of the friction plate 3 showing the first embodiment of the present invention. The friction plate 3 includes a friction surface 25 formed by fixing a plurality of identical friction material segments 12 in an annular shape with an adhesive or the like on the surface in the axial direction of the substantially annular core plate 20. The core plate 20 includes a spline 20 a that engages with the spline 5 of the hub 4 on the inner periphery. In FIG. 2, the friction plate 3 is partially shown, but the friction material segments 12 are fixed to the core plate 20 in an annular and even manner in the same manner as shown in FIG. Yes.

  An oil passage 21 penetrating from the inner diameter to the outer diameter is defined between the friction material segment 12 and the friction material segment 12. Therefore, the friction material segments 12 and the oil passages 21 are alternately arranged in the circumferential direction.

  FIG. 3 is a front view showing the friction material segment 12 used in the friction plate of the first embodiment of the present invention. A plurality of fine grooves 30 extending in the radial direction of the friction material segment 12 are formed on the friction surface (surface) 25 of the friction material segment 12.

  The fine grooves 30 extend radially from the center of the core plate 20 at substantially equal intervals. Further, the friction material segment 12 extends from the inner diameter end to the outer diameter end. That is, the fine groove 30 penetrates from the inner diameter end to the outer diameter end of the friction material segment 12.

  The circumferential width of the fine groove 30 is set to 10 μm to 1000 μm. The depth is 10 μm to 300 μm. This is because when the width is 10 μm or less, there is no drag torque reduction effect, and when the width is 1000 μm or more, the friction area of the friction surface 25 of the friction material segment 12 decreases and the durability deteriorates.

  Further, the depth of the fine groove 30 is set to 10 μm to 300 μm. This is because when the depth is 10 μm or less, there is no drag torque reduction effect, and when the depth is 300 μm or more, the strength of the friction material segment 12 decreases.

  The total area of the fine grooves 30 in the friction surface 25 of one friction material segment 12 is set to 1 to 20% of the area of the friction surface 25. This is because when the area ratio is 1% or less, there is no drag torque reduction effect, and when the area ratio is 20% or more, the friction characteristics of the friction plate 3 deteriorate.

  The friction material segment 12 has an oil groove 12a that opens to the inner diameter side, ends on the outer diameter side and terminates in the friction material segment 12, and opens to the outer diameter side. A terminating oil groove 12b is formed.

  The oil groove 12 a is formed at substantially the center in the circumferential direction of the friction material segment 12. The oil groove 12b is formed at two locations on both sides in the circumferential direction with the oil groove 12a interposed therebetween. By providing the oil groove 12b that opens only on the outer diameter side, the oil drawn into the friction surface 25 from the oil passage 21 is smoothly discharged to the outer diameter side, and drag torque can be reduced during idling. . Particularly in the low rotation region, the effect of reducing the drag torque is great.

  Further, by providing the oil groove 12a that is open at the inner diameter portion and closed at the end, an action of separating the friction plate 3 and the separator plate 2 occurs, and the clearance between the friction plate 3 and the separator plate 2 during idling is reduced. The effect is uniform.

(Second embodiment)
FIG. 4 is a front view of the friction material segment 12 used in the friction plate of the second embodiment of the present invention. In the second embodiment, the extending direction of the fine grooves formed on the friction surface 25 of the friction material segment 12 is different from that of the first embodiment.

  In the second embodiment, a plurality of fine grooves 40 are provided at equal intervals in the circumferential direction of the friction material segment 12. As is clear from FIG. 4, the fine groove 40 extends from one end to the other end in the circumferential direction of the friction material segment 12.

  Also in the second embodiment, the width and depth of the fine groove 40 and the area ratio with respect to the friction surface 25 are set in the same manner as in the first embodiment.

(Third embodiment)
FIG. 5 is a front view of the friction material segment 12 used in the friction plate of the third embodiment of the present invention. The third embodiment has a configuration in which the first embodiment and the second embodiment are combined, and the fine groove 30 extending in the radial direction (radial direction) and the fine groove 40 extending in the circumferential direction cause friction. It is formed on the friction surface 25 of the material segment 12.

  In the third embodiment, since the fine grooves 30 extending in the radial direction at equal intervals and the fine grooves 40 extending in the circumferential direction at equal intervals are formed, the friction surface is larger than that in the first and second embodiments. Although the area ratio with respect to 25 is high, since a surface oil film between the friction plate 3 and the separator plate 2 can be secured, the fluid shear resistance can be reduced.

  As is apparent from FIG. 5, the fine groove 30 extends from the inner diameter end to the outer diameter end of the friction material segment 12, and the fine groove 40 extends from one end to the other end in the circumferential direction of the friction material segment 12. ing.

  Also in the third embodiment, the width and depth of the fine grooves 30 and the fine grooves 40 and the area ratio with respect to the friction surface 25 are set in the same manner as in the first embodiment.

  Needless to say, the friction material segments 12 of the second and third embodiments are fixed to the core plate 20 as shown in FIG. 2 to constitute the friction plate 3 as described in the first embodiment.

  By forming the fine grooves as in the first to third embodiments, the low rotation region of the drag torque in the wet multi-plate clutch can be further effectively reduced. Further, the number of the fine grooves 30 and 40 can be arbitrarily set after ensuring a necessary friction area of the friction surface 25 of the friction material segment 12.

  FIG. 6 is a graph showing the effects of the examples of the present invention and the comparative example (conventional example). The vertical axis represents drag torque (Nm), and the horizontal axis represents relative rotational speed (rpm). In FIG. 6, the shape of the friction material segment is the same, curve A shows a comparative example (conventional example) in which fine grooves are not provided, curve C shows the first embodiment shown in FIG. 3, curve B shows FIG. The second embodiment shown in FIG. 5 and the curve D represent the third embodiment shown in FIG. It can be seen that each example provided with fine grooves can drastically reduce the drag torque in the low rotation region as compared with the comparative example.

  The present invention described above is not limited to the above-described embodiment, and the shape of the friction material segment may be other than the illustrated shape. A friction material segment having a different oil groove configuration or a friction material segment having no oil groove formed is also possible.

  The present invention described above can be used in a vehicle equipped with an automatic transmission.

1 Clutch drum 2 Separator plate 3 Friction plate 4 Hub 5 Spline 6 Piston 8 Spline 10 Wet multi-plate clutch 12 Friction material segment 12a, 12b Oil groove 20 Core plate 21 Oil passage 25 Friction surface 30 Fine groove 40 Fine groove

In order to achieve the above object, the friction plate of the present invention comprises:
A friction plate formed by fixing a plurality of friction material segments in an annular shape to a substantially annular core plate,
A plurality of fine grooves are formed on the surface of the friction material segment ,
Each of the plurality of fine grooves has a width of 10 μm to 1000 μm and a depth of 10 μm to 300 μm, and extends radially from the center of the core plate .

Claims (8)

A friction plate formed by fixing a plurality of friction material segments in an annular shape to a substantially annular core plate,
Fine grooves are formed on the surface of the friction material segment,
The fine groove has a width of 10 μm to 1000 μm and a depth of 10 μm to 300 μm,
The total area of the fine grooves is 1% to 20% of the area of the friction surface of the friction material segment.   The friction plate according to claim 1, wherein the fine groove extends in a radial direction of the friction material segment.   The friction plate according to claim 1, wherein the fine groove extends from an inner diameter end to an outer diameter end of the friction material segment.   The friction plate according to claim 1, wherein the fine groove extends in a circumferential direction of the friction material segment.   5. The friction plate according to claim 1, wherein the fine groove extends from one end to the other end in the circumferential direction of the friction material segment.   The friction plate according to claim 1, wherein the fine groove extends in a radial direction and a circumferential direction of the friction material segment.   The friction material segment includes an oil groove that opens to an inner diameter side and terminates in the friction material segment, and an oil groove that opens to an outer diameter side and terminates in the friction material segment. The friction plate according to any one of claims 1 to 6.   A wet multi-plate clutch comprising the friction plate according to any one of claims 1 to 7, and separator plates alternately arranged in the axial direction with the friction plate.

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