Friction fastening device and molding method thereof

Abstract

To provide a friction fastening device which can form a plurality of oil holes at favorable productivity, and its forming method.SOLUTION: In a friction fastening device 1 of an automatic transmission having a cylindrical drum part 2 for supporting an annular friction plate 41, the drum part 2 comprises: a cylinder part 22a which is recessed toward the outside in a radial direction so as to be fit to a tooth part 42 of the friction plate 41 at an internal peripheral side face, and includes a spline part 25 having a groove part 24 extending along an axis 21 of the drum part 2; a vertical wall part 22c arranged at one end side of the cylinder part 22a, and extending to the inside in the radial direction; and an angular part 22b arranged between the cylinder part 22a and the vertical wall part 22c. A drum recessed part 27 connected to the groove part 24 of the spline part 25, and recessed toward one end side of the axis 21 of the drum part 2 is formed inside the angular part 22b, and oil holes 26 connected to the drum recessed part 27, and opened at the drum recessed part 27 at the outside by a cut part 29 which is cut along a circumferential direction of the drum part 2 are formed outside the angular part 22b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a frictional fastening device and a molding method thereof, and more particularly to a frictional fastening device for an automatic transmission mounted on a vehicle and a molding method thereof. [Background technology]

[0002] A known friction fastening device for an automatic transmission mounted on a vehicle is a wet-type multi-plate clutch that includes a cylindrical drum, a cylindrical hub concentrically arranged inside the drum, a plurality of annular friction plates respectively arranged on the inner periphery of the drum and the outer periphery of the hub, a piston that presses the friction plates together to fasten them together, and a hydraulic chamber that generates hydraulic pressure for the piston to press the friction plates.

[0003] This wet multi-plate clutch is configured to realize vehicle gear changes by controlling the hydraulic pressure in a hydraulic chamber to change the torque generated between a plurality of friction plates pressed by a piston.

[0004] In addition, in wet multi-plate clutches, the surfaces of the friction plates are lubricated with lubricating oil supplied from the inner diameter side, which improves the wear resistance and cooling performance of the friction plates and absorbs the shock when the friction plates are fastened together.

[0005] On the other hand, if lubricating oil remains on the inside of the drum, a drag torque will be generated on the friction plates when the friction plates are not fastened, so it is necessary to provide an oil hole connecting the inside of the drum with the outside so as to drain the lubricating oil between the multiple friction plates.

[0006] For example, Patent Document 1 discloses a wet-type multi-plate clutch in which an oil hole is provided on the inner circumference of the drum to connect the inside of the drum with the outside, in a spline portion having a groove recessed radially outward so as to fit with a friction plate. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6135431 Summary of the Invention [Problem to be solved by the invention]

[0008] On the other hand, in the friction fastening device of Patent Document 1, when providing oil holes in the drum part, it is possible to open multiple oil holes by drilling, for example. However, since the drill position must be adjusted for each oil hole, this increases the processing time, and there is a risk of reducing the productivity of the friction fastening device.

[0009] Therefore, an object of the present invention is to provide a friction fastening device in which a plurality of oil holes can be formed with good productivity, and a molding method thereof. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention is characterized by having the following configuration.

[0011] First, the present invention provides a frictional fastening device for an automatic transmission that includes a cylindrical drum portion supporting an annular friction plate, The friction plate is The outer circumferential surface is provided with teeth that protrude radially outward, The drum unit includes: a cylindrical portion including a spline portion on an inner peripheral side surface, the spline portion having a groove portion extending along an axial direction of the drum portion and recessed radially outward so as to engage with the tooth portion of the friction plate; a vertical wall portion provided on one end side of the cylindrical portion and extending radially inward; a corner portion provided between the cylindrical portion and the vertical wall portion, A drum recess is provided on an inner side of the corner portion, the drum recess being connected to the groove portion of the spline portion and recessed toward one end side in the axial direction of the drum portion, A cutout portion is provided on the outer side of the corner portion, the cutout portion being connected to the drum recess and cut along the circumferential direction of the drum portion, The drum recess is opened to the outside by the cutting portion, and an oil hole is formed. It is characterized by:

[0012] According to the present invention, the friction fastening device is formed by forming the drum part by die casting, for example, and cutting the outside of the corner of the drum part along the circumferential direction by turning, so that the oil holes are provided without adjusting the respective machining positions. Therefore, the friction fastening device provided with the oil holes requires a short machining time, and the productivity is improved.

[0013] The drum portion may be a die-cast product.

[0014] According to this configuration, the drum part of the friction fastening device is formed by die casting, and the oil holes are provided by, for example, cutting the outside of the corners of the drum part along the circumferential direction by turning, without adjusting the respective machining positions. Therefore, the friction fastening device including the drum part provided with the oil holes requires a short machining time, improving productivity.

[0015] Further, a cylindrical piston having an inclined portion that is inclined radially inward toward one end side of the cylindrical portion is disposed between the vertical wall portion and the friction plate on the inside of the cylindrical portion of the drum portion, The inclined portion of the piston may be provided with a lubricant drain hole passing through an inner and outer side of the inclined portion.

[0016] According to this configuration, the lubricating oil remaining inside the piston is discharged to the outside of the piston through the lubricating oil discharge hole provided in the inclined portion of the piston disposed between the inner vertical wall portion of the drum portion and the friction plate when the piston presses the friction plate, thereby suppressing the centrifugal force caused by the lubricating oil from acting on the piston.

[0017] Further, the groove portion of the spline portion provided in the drum portion has a groove side surface that is recessed radially outward along the groove portion and extends along the axial direction of the drum portion, The oil hole may be formed along a side surface of the groove when viewed in the axial direction of the cylindrical portion.

[0018] According to this configuration, the oil hole is formed along the side surface of the groove portion of the spline portion of the drum part, so that the opening area is large and the lubricating oil remaining between the friction plate and the groove portion can be smoothly discharged.

[0019] The present invention also provides a method for molding a friction fastening device for an automatic transmission having a cylindrical drum portion supporting an annular friction plate, the method comprising the steps of: The friction plate is The outer circumferential surface is provided with teeth that protrude radially outward, The drum unit includes: a cylindrical portion having an inner peripheral side surface, the cylindrical portion having a spline portion having a groove portion extending along an axial direction of the drum portion and recessed radially outward so as to engage with the tooth portion of the friction plate; a vertical wall portion provided on one end side of the cylindrical portion and extending radially inward; a corner portion provided between the cylindrical portion and the vertical wall portion, A drum recess is provided on an inner side of the corner portion, the drum recess being connected to the groove portion of the spline portion and recessed toward one end side in the axial direction of the drum portion, The molding method includes: Die-casting the drum part so as to form an extrusion part protruding outwardly on the outer side of the corner part at a position corresponding to the drum recess part; and cutting the extrusion portion of the corner portion of the die-cast drum portion to form a cutting portion connected to the drum recess along a circumferential direction of the drum portion, The drum recess is opened to the outside by the cutting portion, and an oil hole is formed. It is characterized by:

[0020] According to the present invention, the method for forming the friction fastening device forms the drum part by die casting, and then cuts the extrusions provided on the outside of the corners of the drum part along the circumferential direction by turning, for example, to form the oil holes without adjusting the respective machining positions. Therefore, this molding method for forming the oil holes requires a short processing time, improving the productivity of the friction fastening device. Effect of the Invention

[0021] Therefore, according to the friction fastening device and the molding method thereof according to the present invention, a plurality of oil holes can be provided with good productivity. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic cross-sectional view showing a friction fastening device according to an embodiment of the present invention. [Diagram 2] 2 is a schematic front view of a drum portion of the friction fastening device of FIG. 1. [Diagram 3] 3 is a schematic cross-sectional view of the drum unit taken along line III-III in FIG. 2. [Figure 4] 4 is a schematic cross-sectional view of the drum part taken along line IV-IV in FIG. 2. [Diagram 5] 3 is a schematic cross-sectional view of the drum part taken along line VV in FIG. 2. [Figure 6] 3 is an explanatory diagram showing a method of forming oil holes in the corners of the drum part in FIG. 2. FIG. [Figure 7] FIG. 11 is a schematic diagram of a drum portion of a friction fastening device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] Fig. 1 is a schematic cross-sectional view showing a frictional fastening device according to an embodiment of the present invention. As shown in Fig. 1, the frictional fastening device 1 according to the embodiment of the present invention is configured as a frictional fastening device for an automatic transmission mounted on a vehicle.

[0025] The friction fastening device 1 includes a cylindrical drum portion 2, a cylindrical hub portion 3 arranged concentrically inside the drum portion 2, a plurality of annular friction plates 4 arranged side by side along the axis 21 of the drum portion 2 and the axis 31 of the hub portion 3 on the inner circumference of the drum portion 2 and the outer circumference of the hub portion 3, a planetary gear 5 shown by a dashed line arranged inside the hub portion 3, and a piston 6 arranged inside the drum portion 2 on one end side of the drum portion 2 relative to the friction plates 4 and the planetary gear 5, and configured to slide hydraulically along the axis 21 of the drum portion 2 and the axis 31 of the hub portion 3 to press the friction plates 4.

[0026] The drum portion 2 includes a cylindrical first drum cylindrical portion 22a provided around the axis 21 of the drum portion 2, a corner portion 22b provided on one end side of the first drum cylindrical portion 22a and inclined radially inward as it approaches the one end side of the drum portion 2, a first drum vertical wall portion 22c provided on one end side of the corner portion 22b and extending radially inward, a cylindrical second drum cylindrical portion 22d extending from the inner end of the first drum vertical wall portion 22c to the one end side along the axis 21, an inclined portion 22e provided on one end side of the second drum cylindrical portion 22d and inclined radially inward as it approaches the one end side of the drum portion 2, a second drum vertical wall portion 22f provided on one end side of the inclined portion 22e and extending radially inward, and a cylindrical third drum cylindrical portion 22g extending from the inner end of the second drum vertical wall portion 22f to the one end side along the axis 21.

[0027] The drum portion 2 further includes a cylindrical first inner drum cylindrical portion 23a extending along the axis 21 of the drum portion 2 to the other end side between the inclined portion 22e and the second drum vertical wall portion 22f.

[0028] Furthermore, the drum unit 2 includes a cylindrical second inner drum cylindrical portion 23b extending from the other end of the third drum cylindrical portion 22g to the other end side along the shaft 21. A thrust bearing 8 is disposed on the other end side of the second inner drum cylindrical portion 23b, which abuts against the other end of the second inner drum cylindrical portion 23b and one end side of the planetary gear 5 to allow relative rotation between the drum unit 2 and the planetary gear 5.

[0029] A plurality of spline portions 25 having groove portions 24 recessed radially outward and extending along the shaft 21 of the drum portion 2 are provided at equal intervals in the circumferential direction on the inner circumference of the first drum cylindrical portion 22a of the drum portion 2. A plurality of annular drum side friction plates 41 are arranged side by side along the shaft 21 of the drum portion 2 on the inner circumference of the first drum cylindrical portion 22a of the drum portion 2. A plurality of drum side teeth 42 protruding radially outward and arranged at equal intervals in the circumferential direction are provided on the outer circumference of the drum side friction plates 41, and are spline-fitted with the groove portions 24 of the spline portion 25 provided on the inner circumference of the first drum cylindrical portion 22a of the drum portion 2.

[0030] The outer periphery of the hub portion 3 is provided with a plurality of spline portions 33 that are recessed radially inward and have groove portions 32 that extend along the axis 31 of the hub portion 3, and are spaced equally apart in the circumferential direction. In addition, a plurality of annular hub-side friction plates 43 are arranged on the outer periphery of the hub portion 3, aligned along the axis 31 of the hub portion 3. The inner periphery of these hub-side friction plates 43 is provided with a plurality of hub-side teeth 44 that protrude radially inward and are spaced equally apart in the circumferential direction, and are spline-fitted with the groove portions 32 of the spline portions 33 provided on the outer periphery of the hub portion 3.

[0031] A cylindrical piston 6 is fitted into the spaces formed between the second drum vertical wall portion 22f, the first inner drum cylindrical portion 23a, and the second inner drum cylindrical portion 23b of the drum portion 2 and the planetary gear 5. The shaft 61 of the piston 6 extends coaxially with the shaft 21 of the drum portion 2 and the shaft 31 of the hub portion 3.

[0032] The piston 6 includes an annular snap ring 62 attached to the outer periphery of the second inner drum cylindrical portion 23b, a cylindrical spring retainer 63 attached to the outer periphery of the second inner drum cylindrical portion 23b so as to abut one end side of the snap ring 62, a cylindrical piston portion 64 attached to the outer periphery of the second inner drum cylindrical portion 23b so as to be able to slide along the axis 61 between the spring retainer 63 and the second drum vertical wall portion 22f, and a return spring 65 disposed between the spring retainer 63 and the piston portion 64 so as to urge the piston portion 64 toward one end side along the axis 61.

[0033] The spring retainer 63 has a spring retainer recess 63a recessed toward the other end side at one end side of the spring retainer 63. In the space between this spring retainer recess 63a and the piston portion 64, a centrifugal balance hydraulic chamber 66 is formed.

[0034] The piston portion 64 includes, at the other end side of the piston portion 64, a piston recessed portion 64a recessed toward one end side, a piston cylinder portion 64b provided on the outer periphery of the piston portion 64, a piston outer inclined portion 64c extending so as to incline radially inward toward the one end side on the outer periphery of the piston cylinder portion 64b, and a piston pressing portion 64d extending toward the other end side at the other end of the piston outer inclined portion 64c so as to press the drum side friction plate 41 of the drum portion 2 along the shaft 21 of the drum portion 2. The piston portion 64 is configured to slide along the shaft 61 with the outer periphery of the piston cylinder portion 64b fitted into the inner periphery of the first inner drum cylindrical portion 23a of the drum portion 2 and the inner periphery of the piston cylinder portion 64b fitted into the outer periphery of the spring retainer 63.

[0035] Moreover, the piston portion 64 has a piston inner inclined portion 64e that is inclined radially inward toward the other end side at one end side of the piston portion 64. A hydraulic chamber 67 is formed in the space between this piston inner inclined portion 64e and the second drum vertical wall portion 22f.

[0036] The second inner drum cylindrical portion 23b is provided with a centrifugal balance oil supply hole 66a extending radially toward the centrifugal balance hydraulic chamber 66 and an oil supply hole 67a extending radially toward the hydraulic chamber 67.

[0037] Annular oil seals (in FIG. 1, the oil seals are shown as rectangular shapes) are provided between the inner circumference of the piston portion 64 and the outer circumference of the second inner drum cylindrical portion 23b of the drum portion 2, between the inner circumference of the piston cylinder portion 64b and the outer circumference of the spring retainer 63, and between the outer circumference of the piston cylinder portion 64b and the inner circumference of the first inner drum cylindrical portion 23a.

[0038] Lubricating oil is supplied to the inside of the drum part 2 from the radially inner side of the second inner drum cylindrical part 23b. The centrifugal balance hydraulic chamber 66 and the hydraulic chamber 67 of the piston 6 are also configured to receive lubricating oil from a centrifugal balance oil supply hole 66a and an oil supply hole 67a, respectively.

[0039] When lubricating oil is supplied from an oil supply hole 67a provided in the second inner drum cylindrical portion 23b of the drum portion 2 toward the hydraulic chamber 67 of the piston 6, the piston portion 64 of the piston 6 compresses the return spring 65 disposed on the other end side of the piston portion 64 toward the other end side, and slides toward the other end side along the shaft 61. As a result, the piston pressing portion 64d of the piston portion 64 presses the drum side friction plate 41 of the drum portion 2 toward the other end side along the shaft 21 of the drum portion 2, so that the drum side friction plate 41 and the hub side friction plate 43 of the hub portion 3 are fastened to each other.

[0040] Meanwhile, as the lubricating oil is discharged from the hydraulic chamber 67 of the piston 6 through the oil supply hole 67a provided in the second inner drum cylindrical portion 23b of the drum portion 2, the compressed return spring 65 of the piston 6 expands toward the one end side, causing the piston portion 64 of the piston 6 to slide toward the one end side along the shaft 61. As a result, the piston pressing portion 64d of the piston portion 64 leaves the drum side friction plate 41 of the drum portion 2 and moves toward the one end side along the shaft 21 of the drum portion 2, so that the fastening between the drum side friction plate 41 and the hub side friction plate 43 of the hub portion 3 is released.

[0041] When the lubricating oil is discharged from the hydraulic chamber 67 of the piston 6 through the oil supply hole 67a provided in the second inner drum cylindrical portion 23b of the drum portion 2, some of the lubricating oil may remain in the hydraulic chamber 67. At this time, when the vehicle is driven, the piston 6 of the friction fastening device 1 rotates, and centrifugal force is generated in the lubricating oil remaining in the hydraulic chamber 67. Due to this centrifugal force, even though the lubricating oil has been discharged from the hydraulic chamber 67, the piston portion 64 of the piston 6 may slide along the shaft 61 toward the other end side, and the piston pressing portion 64d of the piston portion 64 may press the drum side friction plate 41 of the drum portion 2 toward the other end side along the shaft 21 of the drum portion 2. Therefore, when lubricating oil is discharged from the hydraulic chamber 67, the piston 6 is configured so that the oil pressure in the hydraulic chamber 67, the oil pressure in the centrifugal balance hydraulic chamber 66, and the restoring force of the return spring 65 are balanced by supplying lubricating oil from a centrifugal balance oil supply hole 66a provided in the second inner drum cylindrical portion 23b of the drum portion 2 to the centrifugal balance hydraulic chamber 66 of the piston 6.

[0042] 2 is a schematic front view of the drum unit 2 of the friction fastening device 1 of FIG. A plurality of oil holes 26 are provided on the outside of a corner portion 22b provided between the first drum cylindrical portion 22a and the first drum vertical wall portion 22c of the drum unit 2. The oil holes 26 are provided at equal intervals on the inner circumference of the first drum cylindrical portion 22a, recessed radially outward, and formed to match the circumferential positions of a plurality of spline portions 25 having groove portions 24 extending along the axis 21 of the drum unit 2. In particular, in this embodiment, the oil holes 26 are formed in the circumferential direction at intervals so as to skip each adjacent spline portion 25.

[0043] Fig. 3 is a schematic cross-sectional view of the drum part 2 taken along line III-III in Fig. 2. A drum recess 27 is provided on the inside of a corner 22b provided between the first drum cylindrical part 22a and the first drum vertical wall part 22c of the drum part 2, the drum recess 27 being connected to a groove part 24 of a spline part 25 provided on the inner circumference of the first drum cylindrical part 22a and recessed toward one end along the axis 21 of the drum part 2. The drum recess 27 is formed so as to be connected to an oil hole 26 provided on the outside of the corner 22b.

[0044] The groove 24 of the spline portion 25 provided on the inner circumference of the first drum cylindrical portion 22a is provided with a groove side surface 24a that is recessed radially outward along the groove 24 and extends along the axis 21 of the drum portion 2. This groove side surface 24a extends toward one end along the axis 21 so as to connect with the drum recess 27 provided on the inside of the corner portion 22b.

[0045] Returning to FIG. 2, the oil hole 26 is formed along the groove side surface 24a when viewed from the shaft 21 of the drum portion 2, and therefore appears semicircular.

[0046] Returning to Figure 1, the piston outer inclined portion 64c of the piston portion 64 of the piston 6 arranged inside the first drum cylindrical portion 22a of the drum portion 2 is provided with a lubricating oil drain hole 68 that extends along the axis 61 of the piston 6 so as to pass between the inside and outside of the piston outer inclined portion 64c.

[0047] When the lubricating oil is discharged from the hydraulic chamber 67 of the piston 6 through the oil supply hole 67a provided in the second inner drum cylindrical portion 23b of the drum portion 2, the piston portion 64 of the piston 6 slides along the axis 61 toward one end side, and the fastening between the drum side friction plate 41, which was pressed by the piston pressing portion 64d of the piston portion 64, and the hub side friction plate 43 of the hub portion 3 is released, the lubricating oil remaining inside the piston outer inclined portion 64c of the piston 6 is discharged to the outside of the piston outer inclined portion 64c through the lubricating oil discharge hole 68 provided in the piston outer inclined portion 64c of the piston 6, and can then be discharged to the outside through the oil hole 26 connected to the drum recess 27. In addition, the oil hole 26 formed along the groove side surface 24a of the groove portion 24 of the spline portion 25 provided in the drum portion 2 allows the lubricating oil remaining between the groove portion 24 and the drum side friction plate 41 that is spline-fitted with the groove portion 24 to be smoothly discharged to the outside from the oil hole 26 that is connected to the groove portion 24 via the drum recess 27.

[0048] Fig. 4 is a schematic cross-sectional view of the drum part 2 taken along line IV-IV in Fig. 2. In particular, Fig. 4 shows a cross section between two adjacent spline parts 25 provided on the inner circumference of the first drum cylindrical part 22a. As shown in Fig. 4, the radially outer thickness of the first drum cylindrical part 22a where the spline parts 25 are not provided is greater than the radially outer thickness of the first drum cylindrical part 22a where the spline parts 25 are provided.

[0049] Fig. 5 is a schematic cross-sectional view of the drum part 2 taken along line VV in Fig. 2. In particular, Fig. 5 shows a cross-section of another spline part 25a adjacent to the spline part 25 connected to the oil hole 26, which is provided on the inner periphery of the first drum cylindrical part 22a. The other spline part 25a in Fig. 5 does not have a drum recess connected to the groove side surface 24a of the groove part 24 of the spline part 25 shown in Fig. 3, and no oil hole connected to the drum recess.

[0050] FIG. 6 is an explanatory diagram showing a method for forming the oil hole 26 in the corner portion 22b of the drum portion 2 in FIG.

[0051] 6, the drum part 2 is first formed by die casting so that an extrusion 28 that protrudes outward along a direction perpendicular to the surface of the corner 22b is formed on the outside of the corner 22b at a position corresponding to the drum recess 27 of the drum part 2. As shown in the figure, the extrusion 28 is provided on the outside of the corner 22b radially outward from the intended cutting line 28a indicated by the dashed line.

[0052] The other end side of the first drum cylindrical portion 22a of the drum portion 2, which is a die-cast product produced by die casting, is fixed to a fixture 102 which is rotationally driven by a motor 101. A turning tool 103 extending along the radial direction of the drum portion 2 is disposed on the radial outside of the drum portion 2 so as to face the outer surface of the push-out portion 28. This tool 103 is connected to a tool movement mechanism 104 which moves the tool 103 along the shaft 21 of the drum portion 2 and the radial direction of the drum portion 2. The motor 101 and the tool movement mechanism 104 are electrically connected to a controller 105 disposed outside so that the driving of each of them is controlled.

[0053] In the drum unit 2 arranged as described above, when the oil hole 26 is formed on the outside of the corner portion 22b of the drum unit 2, the motor 101 is rotationally driven based on an electrical signal sent from the controller 105. At this time, the drum unit 2 fixed to the fixture 102 via the first drum cylindrical portion 22a rotates around the shaft 21 together with the fixture 102 rotated by the motor 101.

[0054] Next, the tool moving mechanism 104 is driven based on an electrical signal transmitted from the controller 105, and the cutting tool 103 moves to the other end side along the shaft 21 of the drum part 2, and moves radially inward of the drum part 2 toward the extrusion part 28 provided at the corner part 22b of the drum part 2. The cutting tool 103 moved by the tool moving mechanism 104 is pressed against the extrusion part 28 provided at the corner part 22b of the drum part 2 rotating around the shaft 21. The cutting tool 103 pressed against the extrusion part 28 lathes the extrusion part 28 of the die-cast drum part 2, i.e., the part radially outward from the planned cutting line 28a shown by the broken line, to lathe the drum part 2 so as to form a cutting part 29 connected to the drum recess 27 along the circumferential direction of the drum part 2. By forming the cutting part 29 connected to the drum recess 27, the drum recess 27 is opened to the outside, and the oil hole 26 connected to the drum recess 27 is formed.

[0055] In this manner, in the friction fastening device 1 according to this embodiment, a cut portion 29 is provided on the inside of the corner portion 22b provided between the first drum cylindrical portion 22a and the first drum vertical wall portion 22c so as to connect with the groove portion 24 of the spline portion 25 provided in the drum portion 2, and is cut along the circumferential direction of the drum portion 2 so as to connect with the drum recess 27 recessed into one end side along the axis 21 of the drum portion 2. This cut portion 29 opens the drum recess 27 to the outside, and an oil hole 26 connected to the drum recess 27 is formed.

[0056] In the friction fastening device 1, the drum part 2 is formed by die casting, and the outside of the corner part 22b of the drum part 2 is cut in the circumferential direction by turning, thereby providing the oil hole 26 without adjusting each machining position. Therefore, the friction fastening device 1 including the drum part 2 provided with the oil hole 26 requires a short machining time, improving productivity.

[0057] In addition, the lubricating oil discharge hole 68 provided in the piston outer inclined portion 64c of the piston 6 disposed between the first drum vertical wall portion 22c on the inner side of the drum portion 2 and the friction plate 4 extends along the axis 21 of the drum portion 2. Therefore, when the piston 6 presses the drum side friction plate 41 of the friction plate 4, the lubricating oil remaining inside the piston 6 is discharged to the outside of the piston 6 through the lubricating oil discharge hole 68, thereby making it possible to suppress the centrifugal force caused by the lubricating oil from acting on the piston 6.

[0058] In addition, since the oil hole 26 is formed along the groove side surface 24a of the spline portion 25 provided in the drum portion 2, the opening area is large, and the lubricating oil remaining between the friction plate 4 and the groove portion 24 can be smoothly discharged.

[0059] Furthermore, the method of forming the friction fastening device 1 involves forming the drum part by die casting and cutting the extrusion parts 28 provided on the outside of the corner parts 22b of the drum part 2 along the circumferential direction by turning, thereby making it possible to form the oil holes 26 without adjusting the respective machining positions. Therefore, the molding method of forming the oil holes 26 requires a short processing time, improving the productivity of the friction fastening device 1.

[0060] In the embodiment, the oil hole 26 is formed in a semicircular shape along the groove side surface 24a, but may be formed in a triangular or trapezoidal shape along the groove side surface 24a, for example.

[0061] Fig. 7 is a schematic diagram of a drum portion 202 of a friction fastening device 200 according to another embodiment. As shown in Fig. 7, a plurality of oil holes 290 extending in the radial direction may be provided on the outer periphery of the first drum cylindrical portion 222a of the drum portion 202 so as to connect to grooves of the spline portion provided on the inner periphery of the first drum cylindrical portion 222a.

[0062] The present invention is not limited to the exemplified embodiments, and various improvements and design modifications are possible without departing from the gist of the present invention.

[0063] As described above, according to the present invention, it is possible to easily form multiple oil holes, and therefore the present invention may be suitably used in the field of manufacturing vehicles equipped with automatic transmissions having friction fastening devices. [Explanation of symbols]

[0064] 1 Friction fastening device 2 Drum section 22a Cylindrical portion (first drum cylindrical portion) 22b Corner 22c Vertical wall portion (first drum vertical wall portion) 24 Groove 25 Spline section 26 Oil hole 27 Drum recess 29 Cutting part 41 Friction plate (drum side friction plate) 42 Tooth portion (drum side tooth portion)

Claims

1. A friction fastening device for an automatic transmission having a cylindrical drum portion supporting an annular friction plate, The friction plate is The outer circumferential surface is provided with teeth that protrude radially outward, The drum unit includes: a cylindrical portion including a spline portion on an inner peripheral side surface, the spline portion having a groove portion extending along an axial direction of the drum portion and recessed radially outward so as to engage with the tooth portion of the friction plate; a vertical wall portion provided on one end side of the cylindrical portion and extending radially inward; a corner portion provided between the cylindrical portion and the vertical wall portion, A drum recess is provided on an inner side of the corner portion, the drum recess being connected to the groove portion of the spline portion and recessed toward one end side in the axial direction of the drum portion, A cutout portion is provided on the outer side of the corner portion, the cutout portion being connected to the drum recess and cut along the circumferential direction of the drum portion, The drum recess is opened to the outside by the cutting portion, and an oil hole is formed. A friction fastening device characterized by:

2. 2. The frictional fastening device according to claim 1, wherein the drum portion is a die-cast product.

3. A cylindrical piston having an inclined portion that is inclined radially inward toward one end of the cylindrical portion is disposed between the vertical wall portion and the friction plate on the inside of the cylindrical portion of the drum portion, 3. The frictional fastening device according to claim 1, wherein the inclined portion of the piston is provided with a lubricant oil discharge hole passing through an inside and an outside of the inclined portion.

4. The groove portion of the spline portion of the drum portion has a groove side surface that is recessed radially outward along the groove portion and extends along the axial direction of the drum portion, 4. The friction fastening device according to claim 1, wherein the oil hole is formed along a side surface of the groove portion when viewed in the axial direction of the cylindrical portion.

5. A method for molding a friction fastening device for an automatic transmission having a cylindrical drum portion supporting an annular friction plate, comprising the steps of: The friction plate is The outer circumferential surface is provided with teeth that protrude radially outward, The drum unit includes: a cylindrical portion having an inner peripheral side surface, the cylindrical portion having a spline portion having a groove portion extending along an axial direction of the drum portion and recessed radially outward so as to engage with the tooth portion of the friction plate; a vertical wall portion provided on one end side of the cylindrical portion and extending radially inward; a corner portion provided between the cylindrical portion and the vertical wall portion, A drum recess is provided on an inner side of the corner portion, the drum recess being connected to the groove portion of the spline portion and recessed toward one end side in the axial direction of the drum portion, The molding method includes: Die-casting the drum part so as to form an extrusion part protruding outwardly on the outer side of the corner part at a position corresponding to the drum recess part; and cutting the drum part by cutting the extrusion part of the corner part of the die-cast drum part to form a cut part connected to the drum recess along a circumferential direction of the drum part, The drum recess is opened to the outside by the cutting portion, and an oil hole is formed. A molding method for a friction fastening device comprising the steps of:

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