Friction plate

Abstract

To provide a friction plate with less drag torque without significantly reducing the total area of ​​a friction material. [Solution] The friction material 32 attached in the circumferential direction of the annular plate 34 of the friction plate 30 includes a plurality of groups 321, 322 each formed by three or more piece-shaped friction materials 321a-321d, 322a-322d, each having at least four sides, arranged in a circumferential direction, and the radial dimensions of the piece-shaped friction materials 321a-321d, 322a-322d are configured to be staggered in the circumferential direction. Therefore, when the friction plate 30 is rotating, the lubricating oil can be efficiently discharged to the outer periphery, and the lubricating oil can easily run up onto the surfaces of the piece-shaped friction materials 321a-321d, 322a-322d from the oil grooves between the piece-shaped friction materials 321a-321d, 322a-322d, which has the effect of peeling the friction plate 30 and the mating plate 16 apart. Therefore, the friction plate 30 can have less drag torque without significantly reducing the total area of ​​the friction material 32.

Description

[Technical field]

[0001] The present invention relates to a wet friction plate (hereinafter simply referred to as "friction plate") used in a wet clutch that transmits torque by frictionally engaging a mating plate with the friction plate. [Background technology]

[0002] A wet clutch is usually configured to include a plurality of mating plates that rotate in conjunction with one shaft, and friction plates that are disposed between the mating plates and rotate in conjunction with the other shaft, and a piston is actuated to press the mating plates, causing frictional engagement between the mating plates and the friction plates, thereby transmitting torque between one shaft and the other shaft. The mating plates and the friction plates are cooled by lubricating oil to prevent overheating. Friction material is attached to the surfaces (both sides) of the friction plates that face the mating plates. Oil grooves are provided on the surfaces of the friction materials and between the friction materials so that the lubricating oil is discharged to the outer periphery of the friction plates by centrifugal force.

[0003] In a wet clutch, when the piston is not in operation or when the piston is switched from in operation to out of operation, i.e., when the wet clutch is in a disengaged state, ideally no torque should be transmitted between the mating plate and the friction plate, resulting in no power loss. However, in reality, a considerable amount of torque is transmitted between the mating plate and the friction plate due to the lubricating oil present between the mating plate and the friction plate. This is due to the shear resistance of the lubricating oil, which is dragged in the circumferential direction by the rotating mating plate and passes through the oil grooves of the friction plate when the wet clutch is in a disengaged state. The torque transmitted in this way is called drag torque or drag torque.

[0004] It is generally known that the drag torque is reduced when the total area of ​​the friction material provided on the friction plate is reduced. However, reducing the total area of ​​the friction material reduces the torque transmission ability and braking ability between the mating plate and the friction plate, so reducing the total area of ​​the friction material too much is not effective. Therefore, in order to achieve both the reduction of the drag torque and the torque transmission function between the mating plate and the friction plate, friction plates with various shapes of friction material and oil grooves have been proposed, and examples of these are listed below. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-229765 A

[0006] Patent Document 1 discloses a friction plate in which at least one of the outer peripheral portion and the inner peripheral portion of the friction material is formed into a continuously changing shape so that the distance of the outer peripheral portion and / or the inner peripheral portion of the friction material from the center of rotation of the plate changes continuously between at least two adjacent friction materials, thereby reducing drag torque while suppressing reduction in the area of ​​the friction material.

[0007] It is said that a friction plate using a friction material having a shape like that of Patent Document 1 can reduce drag torque to a certain degree. However, there is always a demand for a further reduction in drag torque, and there is a continuing demand for a friction plate that can further reduce drag torque without significantly reducing the total area of ​​the friction material. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a friction plate that has less drag torque without significantly reducing the total area of ​​the friction material. [Means for solving the problem]

[0009] The present invention relates to a friction plate having a friction material attached to a friction engagement surface of an annular plate in a circumferential direction thereof, The friction material includes a plurality of groups each including three or more piece-shaped friction materials each having at least four sides, the group being arranged in a circumferential direction; The piece-shaped friction materials in the group are The radial dimensions are different, and The radial dimension is formed so as to gradually decrease or increase as a whole, The piece-shaped friction materials of the entire group are arranged such that the inner diameter side edge or the outer diameter side edge of the piece-shaped friction materials is located on the same circumference, The above-mentioned problem is solved by providing a friction plate characterized in that the piece-shaped friction materials of the adjacent groups are configured so as to be symmetrical in the radial direction. Effect of the Invention

[0010] According to the present invention, since the friction material has the above-mentioned configuration, the inner diameter side or the outer diameter side is attached to the plate of the friction plate so that it is stepped in the radial direction. With this configuration, when the friction plate rotates, the lubricating oil can be efficiently discharged to the outer periphery. In addition, since the lubricating oil easily runs up onto the surface of the piece-shaped friction material from the oil groove between the piece-shaped friction materials, the effect of peeling the friction plate and the mating plate is generated. Therefore, it is possible to obtain a friction plate with less drag torque without significantly reducing the total area of ​​the friction material. Note that, when the inner diameter side sides of the entire group of piece-shaped friction materials are arranged to be located on the same circumference, the outer periphery side side of the friction material becomes stepped. In this case, it is possible to easily reduce the area of ​​the friction material immersed in the lubricating oil, so that the stirring resistance can be reduced and energy loss can be reduced.

[0011] In addition, since the radial dimension of the piece-shaped friction material is formed so as to become smaller or larger in a stepwise manner as a whole, when the piece-shaped friction material is punched out from the sheet-shaped friction material, the processing can be performed with a good yield, and the productivity can be improved. [Brief description of the drawings]

[0012] [Figure 1] 1 is a longitudinal sectional view of a radial half of a wet clutch to which the friction plate of the present invention can be applied; [Diagram 2] FIG. 2 is a partial front view of one group of piece-shaped friction materials of the friction plate of the present invention. [Diagram 3] FIG. [Figure 4] FIG. 4 is a partial front view illustrating the flow of lubricating oil relative to the piece-shaped friction material. [Diagram 5] FIG. 4 is a partial front view showing a piece-shaped friction material immersed in lubricating oil. [Figure 6] Graph showing measured drag torque. [Figure 7] FIG. 1 is a first conceptual diagram showing how piece-shaped friction material is punched out from a sheet-shaped friction material. [Figure 8] FIG. 11 is a second conceptual diagram showing the process of punching out piece-shaped friction material from a sheet-shaped friction material. [Figure 9] FIG. 2 is a front view of the friction material according to the first embodiment of the present invention. [Figure 10] FIG. 5 is a front view of a friction material according to a second embodiment of the present invention. [Figure 11] FIG. 7 is a front view of a friction material according to a third embodiment of the present invention. [Figure 12] FIG. 13 is a front view of a friction material according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 12. However, the present invention is not limited to this embodiment.

[0014] FIG. 1 shows a vertical cross-sectional view of a radial half of a wet clutch 10 to which a friction plate 30 of the present invention can be applied. The wet clutch 10 basically has a symmetrical shape with respect to the axial direction. The wet clutch 10 includes a plurality of mating plates 16 spline-fitted to a drum 12 that rotates in conjunction with one shaft (not shown), and a friction plate 30 that is disposed between the mating plates 16 and spline-fitted to a hub 22 that rotates in conjunction with the other shaft (not shown). When a piston 14 in the drum 12 is operated by hydraulic pressure or the like, it presses the mating plate 16, frictionally engaging the mating plate 16 with the friction plate 30. This is configured to transmit torque between one shaft and the other shaft. Since the basic structure of the wet clutch 10 is well known, the friction plate 30 will be described below.

[0015] The friction plate 30 is configured by attaching friction material 32 to the circumferential direction of the friction engagement surface of an annular plate 34. As shown in Fig. 2, the friction material 32 is formed by a plurality of piece-shaped friction materials 321a-321d, each having at least four sides, continuing in the circumferential direction to form one group 321. The friction material 32 as a whole is configured by a plurality of such groups 321 continuing in the circumferential direction. One group 321 includes three or more piece-shaped friction materials 321a-321d.

[0016] The piece-shaped friction materials 321a-321d in the group 321 are configured so that the radial dimension changes continuously as a whole. Specifically, the piece-shaped friction materials 321a-321d are formed so that the radial dimension of each of them shortens in the clockwise direction. Conversely, the piece-shaped friction materials 321a-321d are formed so that the radial dimension of each of them lengthens in the counterclockwise direction. The piece-shaped friction materials 321a-321d in the group 321 are arranged so that their inner diameter sides are located on the same circumference. Therefore, the outer diameter sides of the piece-shaped friction materials 321a-321d are configured so that they have a step in the radial direction, as shown by the arrow X.

[0017] As shown in FIG. 3, the group 321 consisting of the piece-like friction materials 321a to 321d is arranged at equal intervals in a range a of 45° on the annular plate 32. The group 322 consisting of the piece-like friction materials 322a to 322d is arranged adjacent to the group 321 consisting of the piece-like friction materials 321a to 321d in the circumferential direction. In this manner, the groups consisting of the piece-like friction materials are arranged continuously in the circumferential direction to form the friction material 34 as a whole. Here, the piece-like friction materials of adjacent groups, for example, the piece-like friction materials 321a to 321d of the group 321 and the piece-like friction materials 322a to 322d of the group 322 are arranged to be symmetrical in the radial direction. In the case of the friction plate 30, the inner diameter side edges of the piece-like friction materials 321a to 321d of the group 321 and the piece-like friction materials 322a to 322d of the group 322 are arranged to be located on the same circumference with the point 0 as the center.

[0018] FIG. 4 is a partial front view for explaining the flow of lubricating oil to the piece-shaped friction materials 322a to 322d. As shown in the figure, when the friction material 32 rotates with the rotation of the friction plate 30, the lubricating oil flows due to friction with the plate 32 (not shown) and the friction material 32. Note that in FIG. 4, it is assumed that the friction material 32 rotates in the right direction. The lubricating oil flows along the dashed arrow Y between and over the piece-shaped friction materials 322a to 322d and flows to the outer periphery of the friction material 32. As described above, the friction material 32 is attached to the plate 34 so as to have a stepped shape in the radial direction, so that the lubricating oil is efficiently discharged to the outer periphery. In addition, the lubricating oil easily rides up from the oil grooves between the piece-shaped friction materials 322a to 322d onto the surfaces of the piece-shaped friction materials 322a to 322d, which has the effect of peeling off the friction plate 30 and the mating plate 16 (see FIG. 1). Therefore, the friction plate 30 can have a smaller drag torque without significantly reducing the total area of ​​the friction material 32.

[0019] Also, as in friction plate 30, if the inner diameter sides of the entire group including groups 321 and 322 are arranged so as to be positioned on the same circumference, and the outer diameter sides of friction material 32 are staggered, it is easy to reduce the area of ​​friction material 32 that is immersed in lubricating oil 18 accumulated in drum 12, as shown in Fig. 5. Therefore, when friction plate 20 rotates, the agitation resistance with lubricating oil 18 can be reduced, thereby reducing energy loss.

[0020] 6 is a graph showing the drag torque (Nm) values ​​for each rotation speed (rpm) of the conventional friction plate A and the friction plate 30 of the present invention (friction plate B in the figure). As shown in the figure, the drag torque of the friction plate 30 is lower than that of the friction plate A from low rotation speed (left side in the figure) to high rotation speed (right side in the figure).

[0021] 7 and 8 are conceptual diagrams showing the state when the friction materials 132, 32a are punched out from the friction material sheets 140, 40 of the same size. The friction material 132 shown in FIG. 7 has almost the same shape of the piece-shaped friction materials 132a, 132b. On the other hand, the piece-shaped friction materials 323a, 323b of the friction material 32a shown in FIG. 8 are formed so that the radial dimension is gradually smaller or larger as a whole. As is clear from FIGS. 7 and 8, the friction material 32a can punch out more piece-shaped friction materials 323a, 323b from the friction material sheets 140, 40 of the same size than the case of the friction material 132. Therefore, if the piece-shaped friction materials 323a, 323b are formed so that the radial dimension is gradually smaller or larger as a whole, they can be processed with a good yield and productivity can be improved.

[0022] 9 is a front view showing the overall arrangement of the above-mentioned friction material 32. In the friction material 32, groups 321 and groups 322 each consisting of a plurality of piece-like friction materials are provided alternately and continuously in the circumferential direction. As shown in the figure, the piece-like friction materials of adjacent groups 321 and 322 are symmetrical in the radial direction.

[0023] 10 is a front view showing the overall arrangement of the friction material 32a according to the second embodiment of the present invention. In the friction material 32a, a group 323 consisting of seven piece-shaped friction materials 323a, 323b (323c and onwards are omitted) and a group 324 consisting of seven piece-shaped friction materials 324a, 324b (324c and onwards are omitted) are arranged alternately in the circumferential direction. In the case of the friction material 32a, similar to the friction material 32, the piece-shaped friction materials 323a, 323b in the group 323 and the piece-shaped friction materials 324a, 324b in the group 324 are configured so that the radial dimensions change continuously as a whole. On the other hand, the piece-shaped friction materials 323a, 323b in the group 323 and the piece-shaped friction materials 324a, 324b in the group 324 are arranged so that their outer diameter sides are located on the same circumference. For this reason, the inner diameter sides of the piece-shaped friction materials 323a, 323b, 324a, and 324b are configured to have a stepped shape in the radial direction. With this configuration as well, the same effect as that of the friction material 32 can be obtained.

[0024] 11 is a front view showing the overall arrangement of a friction material 32b according to a third embodiment of the present invention. In the friction material 32b, a group 325 consisting of five piece-shaped friction materials 325a, 325b (325c and onwards are omitted) and a group 326 consisting of five piece-shaped friction materials 326a, 326b (326c and onwards are omitted) are continuously and alternately arranged in the circumferential direction. In the friction material 32b, a pair of additional friction materials 33a, 33b having a different shape from the piece-shaped friction materials are arranged between adjacent piece-shaped friction materials of adjacent groups 325, 326. The piece-shaped friction materials 325a, 325b in group 325 and the piece-shaped friction materials 326a, 326b in group 326 of the friction material 32b are configured so that the radial dimensions change continuously as a whole, and are arranged so that their inner diameter sides are located on the same circumference. For this reason, the outer diameter sides of the piece-shaped friction materials 325a, 325b, 326a, and 326b are configured to have a stepped shape in the radial direction. The inner diameter sides of the additional friction materials 33a and 33b are also arranged to be positioned on the same circumference as the inner diameter sides of the piece-shaped friction materials 325a, 325b, 326a, and 326b.

[0025] The additional friction materials 33a and 33b are disposed between the smallest piece-shaped friction material among the piece-shaped friction materials 325a and 325b and the smallest piece-shaped friction material among the piece-shaped friction materials 326a and 326b. The shapes of the additional friction materials 33a and 33b are symmetrical, and each has an inner diameter side, an outer diameter side, a lateral short side, a lateral long side, and an oblique side connecting the lateral short side and the outer diameter side. The pair of additional friction materials 33a and 33b are disposed so that their lateral long sides face each other. It is preferable that the lateral short sides of the additional friction materials 33a and 33b have a dimension shorter than the shortest side of the piece-shaped friction materials 325a, 325b, 326a, and 326b, and the lateral long sides have a dimension longer than the longest side of the piece-shaped friction materials 325a, 325b, 326a, and 326b. This configuration makes it possible to prevent a reduction in the total area of ​​the friction material 32b and to provide a friction plate with low drag torque.

[0026] 12 is a front view showing the overall arrangement of a friction material 32c according to a fourth embodiment of the present invention. In the friction material 32c, a group 327 consisting of six piece-shaped friction materials 327a, 327b (omitted from 327c onwards) and a group 328 consisting of six piece-shaped friction materials 328a, 328b (omitted from 328c onwards) are continuously and alternately arranged in the circumferential direction. In the friction material 32c, a pair of additional friction materials 35a, 35b having a different shape from the piece-shaped friction materials are arranged between adjacent piece-shaped friction materials of adjacent groups 327, 328. The piece-shaped friction materials 327a, 327b in group 327 and the piece-shaped friction materials 328a, 328b in group 328 of the friction material 32c are configured so that the radial dimensions change continuously as a whole, and are arranged so that their outer diameter sides are located on the same circumference. For this reason, the inner diameter sides of the piece-shaped friction materials 327a, 327b, 328a, and 328b are configured to have a stepped shape in the radial direction. The outer diameter sides of the additional friction materials 35a and 35b are also arranged to be positioned on the same circumference as the outer diameter sides of the piece-shaped friction materials 327a, 327b, 328a, and 328b.

[0027] The additional friction materials 35a and 35b are disposed between the smallest piece-shaped friction material among the piece-shaped friction materials 327a and 327b and the smallest piece-shaped friction material among the piece-shaped friction materials 328a and 328b. The shape of the additional friction materials 35a and 35b is symmetrical, and each has an inner diameter side, an outer diameter side, a lateral short side, a lateral long side, and an oblique side connecting the lateral short side and the inner diameter side. The pair of additional friction materials 35a and 35b are disposed so that their lateral long sides face each other. It is preferable that the lateral short side of the additional friction materials 35a and 35b has a dimension shorter than the shortest side of the piece-shaped friction materials 327a, 327b, 328a, and 328b, and the lateral long side has a dimension longer than the longest side of the piece-shaped friction materials 327a, 327b, 328a, and 328b. This configuration makes it possible to prevent a reduction in the total area of ​​the friction material 32c and to provide a friction plate with low drag torque.

[0028] Although the embodiment of the present invention has been described above, the number of piece-shaped friction materials in a group is not limited to the number of piece-shaped friction materials in the above-mentioned embodiment, and may be 3 or more. In addition, the piece-shaped friction material may be configured to have an oil groove of any shape on the surface thereof.

[0029] As described above, according to the present invention, it is possible to provide a friction plate having a smaller drag torque without significantly reducing the total area of ​​the friction material. [Explanation of symbols]

[0030] 30 Friction plate 32 Friction material 34 Plate 321a~321d, 322a~322d, 323a, 323b, 324a, 324b, 325a, 325b, 326a, 326b, 327a, 327b, 328a, 328b Piece-shaped friction material 321,322,323,324,325,326,327,328 Group

Claims

[Claim 1] In a friction plate in which a friction material is attached to the friction engagement surface of an annular plate in the circumferential direction, The friction material includes a plurality of groups each including three or more piece-shaped friction materials each having at least four sides, the group being arranged in a circumferential direction; The piece-like friction materials in the group are each formed so that their radial dimensions are different from one another and that their radial dimensions as a whole become smaller or larger in a stepwise manner, The piece-shaped friction materials of the entire group are arranged such that the inner diameter side edge or the outer diameter side edge of the piece-shaped friction materials is located on the same circumference, The piece-shaped friction materials of the adjacent groups are configured to be symmetrical in the radial direction. friction plate.

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