JP2003004065A - Friction engagement device - Google Patents

Abstract

(57) [Summary] To provide a friction engagement device that reduces the impact when a friction plate is pressed and does not become longer in the axial direction. SOLUTION: A large-diameter cylindrical body 62 in which an outer engaging groove 63 is formed in the axial direction of an inner peripheral surface, and an inner engaging groove 64 formed in the large-diameter cylindrical body 62 in the axial direction of the outer peripheral surface. A small-diameter cylindrical body 61, a plurality of annular large-diameter friction plates 65 movably mounted in the large-diameter cylindrical body 62 in the axial direction, and a plurality of axially movably mounted in the small-diameter cylindrical body 61. A contact portion 65b having an annular small-diameter friction plate 66 and having an outer peripheral portion of the large-diameter friction plate 65 and an inner peripheral portion of the small-diameter friction plate 66 inclined toward another axially adjacent plate of the same type; 66
b is provided. When the friction plates 65 and 66 are pressed, the contact portions 65b and 66b are compressed and deformed, and the friction engagement devices can be smoothly fastened to press the adjacent friction plates 65 and 66 with each other.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction engagement device which is incorporated in a power transmission system such as an automatic transmission for a vehicle to constitute a clutch or a brake. 2. Description of the Related Art A power transmission system for transmitting an engine output to driving wheels is constituted by various devices such as a starting clutch, a transmission, a propulsion shaft, and a final reduction gear. An automatic transmission that automatically performs a shift operation according to the traveling state of a vehicle includes a planetary gear type automatic transmission that has a planetary gear or the like as a transmission mechanism and switches to a predetermined gear according to the traveling state. In addition, there is a continuously variable transmission (CVT) that sets a speed ratio in a stepless manner according to a traveling state. An automatic transmission incorporates a friction engagement device having a plurality of annular friction plates in order to select a power transmission path and set a gear position. In a friction engagement device in which a friction plate is mounted between a large-diameter clutch drum and a small-diameter clutch hub disposed therein, when the friction plate is engaged, the clutch drum and the clutch hub are fastened. It transmits rotational power and is called a clutch. On the other hand, a friction engagement device in which a friction plate is mounted between a fixed large-diameter cylinder such as a transmission case and a small-diameter brake hub disposed inside the friction case, a brake is applied when the friction plate is engaged. The hub will be fixed and is called a brake. [0004] The continuously variable transmission is provided with a forward / reverse switching device for switching the rotational power from the starting device between a forward direction and a reverse direction. The forward / reverse switching device changes the power rotation direction of the planetary gear mechanism. A clutch and brake are provided for switching. In a power transmission system of a four-wheel drive vehicle, a center differential device is used in order to distribute driving force to a front wheel and a rear wheel, and some of the center differential devices also include a friction engagement device. . [0005] The friction engagement device has a plunger or a piston which is operated by hydraulic pressure to bring the friction plate into an engaged state, and is brought into an engaged state when the plunger presses the friction plate in the axial direction. If the plunger suddenly applies a pressing force to the friction plate, a shift shock may be generated from the automatic transmission. [0006] In order to improve the shift shock, a friction engagement device which can be smoothly engaged is required. For example, as disclosed in Japanese Patent Application Laid-Open No. 10-184723, a friction plate is pressed. By attaching an annular wave spring having a wavy portion that generates a spring force between the plunger and the friction plate, the pressing force is gradually applied to the friction plate via the wave spring to reduce the shock at the time of fastening. Relaxing friction engagement devices have been developed. Further, instead of a wave spring, a friction engagement device in which an annular dish plate having a cone portion generating a spring force is mounted between a friction plate and a piston has been developed. A dish plate or a wave spring is manufactured by cutting an annular plate from a flat spring material by punching or the like and forming a corrugated portion or a cone portion. Although it was a simple part, the yield from the material was low and it was an expensive part. Further, since a dish plate or a wave spring is added to the friction engagement device, the friction engagement device has been lengthened in the axial direction. Furthermore, in a friction engagement device having dimensional restrictions, since the amount of deformation of a dish plate or a wave spring at the time of pressing is restricted, it is possible to set an optimal load characteristic at the time of pressing the friction plate. could not. SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost frictional engagement device that reduces the impact when the friction plate is pressed and does not become longer in the axial direction. According to the present invention, there is provided a friction engagement device comprising: a large-diameter cylindrical body having an axially extending outer engaging groove formed on an inner peripheral surface; A small-diameter cylindrical body having an inner engaging groove formed in an outer peripheral surface thereof and extending in the axial direction; and a plurality of small-diameter cylindrical bodies engaged with the outer engaging groove and movably mounted in the large-diameter cylindrical body in the axial direction. An annular large-diameter friction plate, and a plurality of annular small-diameter friction members that are engaged with the inner engagement grooves, are disposed between the large-diameter friction plates, and are axially movably mounted on the small-diameter cylindrical body. A plate, and at least one of an outer peripheral portion of the large-diameter friction plate and an inner peripheral portion of the small-diameter friction plate is provided with a contact portion inclined toward another axially adjacent plate of the same type. Generating a spring force in a direction away from the plates via the contact portion. I do. According to the present invention, when the large-diameter friction plate and the small-diameter friction plate are pressed, the contact portions are each compressed by having the contact portion inclined toward the other plate of the same type adjacent in the axial direction. After being deformed, the adjacent large-diameter friction plate is pressed against the small-diameter friction plate, so that the friction engagement device can be smoothly engaged. According to the present invention, there is provided a low-cost friction engagement device which does not increase in the axial direction without adding a new member to form a contact portion on the friction plate. Can be. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a skeleton diagram showing an automatic transmission having a plurality of friction engagement devices according to an embodiment of the present invention. The automatic transmission has an input shaft 11 connected to the engine 10 and an output shaft 13 provided on a concentric axis of the input shaft 11 and connected to a center differential device 12. It has a front wheel output shaft 14 and a rear wheel output shaft 15 that connect the wheels. The input shaft 11, the output shaft 13, the front wheel output shaft 14, and the rear wheel output shaft 15 are installed in a transmission case (not shown) facing the traveling direction of the vehicle, and the automatic transmission is arranged vertically. 4
Applied to wheel drive vehicles. A torque converter 17 is connected to a crankshaft 16 of the engine 10, and an input shaft 11 is connected to a turbine shaft 18 which is an output shaft of the torque converter 17. A rear sun gear 20 is fixed to an end of the input shaft 11, and a plurality of rear pinion gears 22 rotatably supported by a rear carrier 21 are mounted radially outward of the rear sun gear 20 so as to mesh with the rear sun gear 20. A rear ring gear 23 having teeth on the inner peripheral surface is fitted in mesh with the rear pinion gear 22 radially outward of the rear sun gear 20. The rear sun gear 20 and the rear ring gear 23 are connected via the rear pinion gear 22. I have. Thus, the rear planetary gear train 24 is configured by the rear sun gear 20, the rear ring gear 23, and the rear pinion gear 22. The input shaft 11 has a front sun gear 2.
A plurality of front pinion gears 27 rotatably supported by a front carrier 26 are provided radially outward of the front sun gear 25.
It is fitted in mesh with. A front ring gear 28 having teeth on its inner peripheral surface is fitted in mesh with the front pinion gear 27 radially outward of the front sun gear 25, and the front sun gear 25 and the front ring gear 28 are connected via the front pinion gear 27. Have been. As described above, the front sun gear 25, the front ring gear 28, and the front pinion gear 27 form a front planetary gear train 29. The input shaft 11 has a clutch drum 3
0 is fixed, and a high-speed clutch hub 31 connected to the front carrier 26 and a reverse clutch hub 32 connected to the front sun gear 25 are rotatably mounted on the input shaft 11 radially inward of the clutch drum 30. Have been.
A plurality of friction plates 33 and 34 are mounted between the clutch drum 30 and the high-speed clutch hub 31 and the reverse clutch hub 32, respectively.
And a reverse clutch 36. By pressing the friction plates 33 and 34, the clutch drum 30 is connected to the high-speed clutch hub 31 or the reverse clutch hub 32, and the front carrier 26 or the front sun gear 25 rotates integrally with the input shaft 11. A first brake hub 37 is fixed to the reverse clutch hub 32, and a first brake drum 38 is formed on the inner wall surface of the transmission case. A plurality of friction plates 39 are mounted between the first brake hub 37 and the first brake drum 38 to form a first brake 40. When the friction plate 39 is pressed, the rotation of the front sun gear 25 is stopped because the first brake hub 37 is fixed to the transmission case. A low-speed clutch drum 41 is fixed to the front carrier 26, and a low-speed clutch hub 42 is fixed to the outer peripheral surface of the rear ring gear 23. A plurality of friction plates 43 are mounted between the low-speed clutch drum 41 and the low-speed clutch hub 42.
Is configured. When the friction plate 43 is pressed, the rear ring gear 23 and the front carrier 26 are connected and rotate integrally. A second brake hub 46 connected to the transmission case via a one-way clutch 45 is fixed to an end of the low-speed clutch drum 41, and a second brake drum 47 is formed on the inner wall surface of the transmission case. I have. A plurality of friction plates 48 are mounted between the second brake hub 46 and the second brake drum 47,
A brake 49 is configured. This friction plate 48
Is pressed, the second brake hub 46 is fixed to the transmission case, so that the front carrier 26 is fixed and the revolving motion of the front pinion gear 27 is stopped. The second brake hub 46 is connected to the transmission case via a one-way clutch 45. When the pressing operation of the friction plate 48 is released, the revolving motion of the front pinion gear 27 can be performed only in one direction. The front ring gears 28 of the two planetary gear trains 24 and 29 are connected to the rear carrier 21, and the output shaft 13 is connected to the rear carrier 21. A plurality of clutches 35 and 36 as friction engagement devices are provided. , 44 and the plurality of brakes 40, 49, the rotation of the input shaft 11 is controlled by the two planetary gear trains 2.
The power is transmitted to the output shaft 13 via 4, 29. A center differential device 12 is mounted between the output shaft 13 and a rear wheel output shaft 15 provided on a concentric shaft of the output shaft 13. The center differential device 12 is of a compound planetary gear type. A first sun gear 50 is fixed to one end of the output shaft 13, and a second sun gear 51 is fixed to the rear wheel output shaft 15. Radially outward of the first sun gear 50 and the second sun gear 51
A plurality of integrated pinion gears 52 meshing with the sun gear 50 and the second sun gear 51 are arranged, and a carrier 53
It is supported rotatably. A front wheel drive gear 58 is integrally provided at a front end (left side in FIG. 1) of the carrier 53, and a front wheel driven gear 59 provided at one end of the front wheel output shaft 14 meshes with the carrier to transmit power to the front wheels. With such a configuration, the output of the automatic transmission is controlled by the first sun gear 5 of the center differential device 12.
When input to 0, power is distributed and transmitted to the second sun gear 51 and the carrier 53 supporting the integrated pinion gear 52 via the integrated pinion gear 52, so that the front wheel and the rear wheel can be driven together. . At this time, the rotation difference between the front and rear wheels is differentially absorbed by the rotation of the integrated pinion gear 52. A differential limiting clutch hub 54 is fixed to the rear wheel output shaft 15, and a differential limiting clutch drum 55 is fixed to an end of the carrier 53. A plurality of friction plates 56 are mounted between the differential limiting clutch hub 54 and the differential limiting clutch drum 55 to form a differential limiting clutch 57. Thus, when the front wheels or the rear wheels slip and a large differential rotation occurs, the differential limiting clutch 57 is engaged to suppress the differential rotation. The frictional engagement devices 35, 36, 40, 44, and 4 that are engaged when the power transmission path of such an automatic transmission is selected and the first to fourth speeds and the reverse speed are changed are performed.
9 and 57 will be described. When traveling with the first speed ratio selected, the low-speed clutch 44 is engaged, and the rotation of the input shaft 11 is reduced via the rear planetary gear train 24. At this time, since the rear ring gear 23 is connected to the transmission case via the one-way clutch 45,
During acceleration, the rear ring gear 23 is fixed, and the rear pinion gear 22 revolves around the rear sun gear 20 to transmit rotation to the output shaft 13. When the second speed is selected, the low speed clutch 44 and the first brake 40 are engaged. Since the front sun gear 25 is fixed and the front carrier 26 and the rear ring gear 23 are connected, the rotation speed of the rear ring gear 23 is increased as compared with the first speed. When the third speed is selected, the low speed clutch 44 and the high speed clutch 35 are engaged. Input shaft 11
And the rear ring gear 23 are connected via a high-speed clutch 35 and a low-speed clutch 44, so that the input shaft 11
Is transmitted to the output shaft 13 as it is. When the fourth speed is selected, the high speed clutch 35 and the first brake 40 are engaged. Since the front sun gear 25 is fixed and the front carrier 26 and the input shaft 11 are connected, the speed is increased by the rotation of the front ring gear 28 compared to the third speed. When the reverse is selected, the reverse clutch 36 and the second brake 49 are engaged. Since the input shaft 11 and the front sun gear 25 are connected and the revolving motion of the front pinion gear 27 is suppressed, the rotation of the input shaft 11 is inverted by the front ring gear 28 and transmitted to the output shaft 13. In such an automatic transmission, the plurality of clutches 35, 36, 44 and the brakes 40, 49, which are frictional engagement devices, are engaged to convert the rotation of the input shaft 11 to a center differential. The traveling performance of the four-wheel drive is improved by controlling the engagement of the differential limiting clutch 57 which is a friction engagement device that transmits to the device 12 and performs four-wheel drive traveling. For this reason, the engagement control of the friction engagement device is always performed according to the traveling state, and in order to perform a smooth shift operation, it is necessary to reduce the impact at the time of engagement of the friction engagement device. FIG. 2 is a sectional view along the axial direction showing a part of the frictional engagement device according to one embodiment of the present invention, and FIG. 3 is a sectional view along the line AA in FIG. FIG. 4 is a perspective view showing a part of a contact portion 65b provided on an outer peripheral portion of the large-diameter friction plate 65 when the friction plates are overlapped, and FIG. 5 is a small diameter when the friction plates are overlapped. FIG. 4 is a perspective view showing a part of a contact portion 66b provided on an inner peripheral portion of a friction plate 66. In the frictional engagement device shown in FIGS. 2 and 3, the hub 61, which is a small-diameter cylinder, is driven to rotate, and the drum 62, which is a large-diameter cylinder, is driven to rotate by pressing a friction plate. Although the description will be made as a device, the friction engagement device in which the drum 62 is driven and the hub 61 is driven is the same in structure, and the friction engagement device in which the drum 62 or the hub 61 is fixed and the rotational drive is stopped by fastening. The same applies to A plurality of outer engagement grooves 6 are formed on the inner peripheral surface of the large-diameter cylindrical body, that is, the drum 62 in the axial direction.
A plurality of inner engagement grooves 64 are formed in the axial direction on the small-diameter cylindrical body disposed radially inward of the drum 62, that is, on the outer peripheral surface of the hub 61. The large-diameter friction plate 65 mounted in the outer engagement groove 63 of the drum 62 has a friction surface 65a formed in a thin annular shape. As shown in FIG.
A plurality of contact portions 65b corresponding to the outer engagement grooves 63 are formed in the outer peripheral portion of the outer engagement groove 63.
b is engaged. Thus, while the large-diameter friction plate 65 is supported by the drum 62 and can slide in the axial direction, the movement in the circumferential direction is restricted by the outer engagement groove 63. The contact portion 65b is formed so as to be inclined with respect to the friction surface 65a as shown in FIG. 2, and the contact portions 65b adjacent to each other in FIG. I have. The contact portion indicated by a solid line in FIG. 2 is a contact portion 65b overlapping BB in FIG.
The contact portions indicated by broken lines and dashed lines in FIG.
This is a contact portion overlapping C and DD. The small-diameter friction plate 66 mounted in the inner engaging groove 64 of the hub 61 has a friction surface 66a formed in a thin annular shape. As shown in FIG. 3, the inner peripheral portion of the friction surface 66a has a plurality of contact portions 6 corresponding to the inner engagement grooves 64.
6b are formed, and the contact portions 66b
Are engaged. As described above, the small-diameter friction plate 66 is supported by the hub 61 and can slide in the axial direction, while the movement in the circumferential direction is restricted by the inner engagement groove 64. The contact portion 66b is formed so as to be parallel or inclined with respect to the friction surface 66a as shown in FIG. 2, and the inclination directions are respectively reversed with respect to the contact portion 66b parallel to the friction surface 66a. The contact portion 66b is formed so as to be as shown in FIG. The contact portion 66b indicated by a solid line in FIG. 2 is a contact portion 66b overlapping BB in FIG. 3, and the contact portions indicated by broken lines and alternate long and short dash lines in FIG. 2 are respectively CC and DD in FIG. This is the contact part overlapping with. As shown in FIG. 2, the large-diameter friction plate 65
And the small-diameter friction plate 66 are alternately in contact with each other in the outer engagement groove 63 of the drum 62 or the inner engagement groove 6 of the hub 61.
4 is attached. As shown in FIGS. 4 and 5, at the time of attachment, the contact portions 65 b formed on the large-diameter friction plate 65 are attached in a direction in which the ends contact each other, and similarly, the small-diameter friction plate 66 is formed to be inclined. It is mounted in such a direction that the ends of the contact part 66b contact each other. A stopper 68 whose axial movement is restricted by a snap ring 67 and a pressing member 69 that transmits a pressing operation to the friction plates 65 and 66 are provided at both ends of the mounted friction plates 65 and 66, respectively. It is mounted in the outer engagement groove 63. In this friction engagement device, when the pressing member 69 slides in the axial direction toward the stopper 68, the adjacent friction plates 65 and 66 are pressed by the pressing operation. From the start of sliding of the pressing member 69 to the fastening of the friction plates 65 and 66, the large-diameter friction plate 65 and the small-diameter friction plate 66
Abutment portions 65 that abut against each other between similar friction plates
The large-diameter friction plate 65 and the small-diameter friction plate 66 come into contact with each other while compressively deforming the b and 66b. The sliding contact portions 65b and 66b having a spring force increase in the deformation amount due to the increased pressing load, and the distance between the friction plates 65 and 66 is reduced by the increase in the deformation amount. Therefore, the large-diameter friction plate 65 and the small-diameter friction plate 66 gradually contact each other without sudden contact. Further, the pressing load from the contact to the fastening does not rise sharply because of the abutting portions 65b and 66b having the spring force, so that the friction plates 65 and 66 are fastened smoothly, and the driving force of the hub 61 is reduced.
2 can be transmitted. As described above, in order to reduce the impact when the friction plate is fastened, the impact can be alleviated without performing load control of the plunger or the like by the hydraulic control valve. Further, by providing the contact portions 65b and 66b integrally with the friction plates 65 and 66, a frictional engagement device that does not increase in the axial direction without adding a new member can be provided at low cost. Can be. FIG. 6 is a perspective view of another embodiment showing a part of the contact portion 66b mounted on the hub 61 of the plurality of small-diameter friction plates 66. As shown in FIG. 6, all the contact portions 66b may be formed so as to be inclined with respect to the friction surface 66a, and when formed in this manner, even when the pressing load is set high, etc. A friction plate can be fastened. The amount of deformation of the contact portions 65b and 66b to such a pressing load, that is, the setting of the load characteristics is
As shown in FIG. 6, the number of the contact portions 65b, 66b formed to be inclined with respect to the friction surfaces 65a, 66a is changed, and further, the inclination angle when the contact portions 65b, 66b are formed, the contact portion 6
It can be easily changed by adjusting the circumferential width of 5b and 66b. The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the scope of the present invention. For example, although the friction engagement device shown in the embodiment of the present invention is used for an automatic transmission, it can also be used for a continuously variable transmission and is not limited thereto. Further, the contact portions 65b and 66b are engaged with the engaging grooves 63 and 64, but the contact portions 65b and 66b which do not engage with the engaging grooves 63 and 64 may be set. Further, when the pressing load is set low, the contact portion 65
The friction engagement device may be configured by using the friction plates 65 and 66 having the contact portions 65b and 66b and the friction plates 65 and 66 having no contact portions 65b and 66b. According to the present invention, when the large-diameter friction plate and the small-diameter friction plate are pressed, the contact portion is inclined toward the other similar plate adjacent in the axial direction. Since the adjacent large-diameter friction plate and small-diameter friction plate are pressed against each other after the contact portions are compressed and deformed, the friction engagement device can be smoothly fastened. According to the present invention, there is provided a low-cost friction engagement device which does not increase in the axial direction without adding a new member to form a contact portion on the friction plate. Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a skeleton diagram showing an automatic transmission having a plurality of friction engagement devices according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a part of the friction engagement device according to one embodiment of the present invention. FIG. 3 is a sectional view taken along line AA of FIG. 2; FIG. 4 is a perspective view showing a part of a contact portion provided on an outer peripheral portion of the large diameter friction plate when the friction plates are overlapped. FIG. 5 is a perspective view showing a part of a contact portion provided on an inner peripheral portion of the small-diameter friction plate when the friction plates are overlapped. FIG. 6 is a perspective view showing a part of a contact portion provided on an outer peripheral portion of a large-diameter friction plate when friction plates according to another embodiment of the present invention are overlapped. [Description of Signs] 30 Clutch drum (large-diameter cylinder) 31 High-speed clutch hub (small-diameter cylinder) 32 Retraction clutch hub (small-diameter cylinder) 37 First brake hub (small-diameter cylinder) 38 First brake drum (large-diameter) 41) Low-speed clutch drum (large-diameter cylinder) 42 Low-speed clutch hub (small-diameter cylinder) 46 Second brake hub (small-diameter cylinder) 47 Second brake drum (large-diameter cylinder) 54 Differential-limit clutch hub ( Small-diameter cylinder 55 Differential clutch drum (Large-diameter cylinder) 61 Hub (Small-diameter cylinder) 62 Drum (Large-diameter cylinder) 63 Outer engagement groove 64 Inner engagement groove 65 Large-diameter friction plate 65b Contact part 66 Small diameter friction plate 66b Contact part

Claims (1)

Claims: 1. A large-diameter cylindrical body having an outer engaging groove extending in an axial direction on an inner peripheral surface thereof; and a large-diameter cylindrical member disposed inside the large-diameter cylindrical body and having an axially extending outer peripheral surface. A small-diameter cylindrical body having an extending inner engaging groove formed therein; a plurality of annular large-diameter friction plates engaged with the outer engaging groove and movably mounted in the large-diameter cylindrical body in an axial direction; A plurality of annular small-diameter friction plates that are engaged with the inner engagement grooves, are disposed between the large-diameter friction plates, and are axially movably mounted on the small-diameter cylindrical body; At least one of the outer peripheral portion of the plate and the inner peripheral portion of the small-diameter friction plate is provided with a contact portion inclined toward another axially adjacent plate of the same type,
A friction engagement device, wherein a spring force is generated in a direction away from the plates via the contact portion.