JP2023056902A - friction engagement device - Google Patents

Abstract

To provide a friction engagement device which can maintain a fastening state without continuing to supply working fluid, has a small number of components, and achieves high productivity.SOLUTION: In a friction engagement device 100, working fluid is supplied to cause a piston 30 to move to the other side in an axial direction while compressing a first elastic body 34. Further, a projection 36 moves along a third inclination part to actuate a torque transmission mechanism 40 while rotating in a circumferential direction. When supply of the working fluid is stopped, the piston 30 is pushed back to one side in the axial direction by repulsive force of the first elastic body 34. Further, the projection 36 engages with a first engagement point or a second engagement point along a first inclination part or a second inclination part. When the projection 36 engages with the first engagement point, the torque transmission mechanism 40 is turned into a release state. When the projection 36 engages with second engagement point, an engagement state of the torque transmission mechanism 40 is maintained.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a frictional engagement device capable of maintaining an engaged state even after the supply of hydraulic pressure is stopped.

Friction engagement devices such as multi-disc clutches and multi-disc brakes used in automobile transmissions use hydraulic pressure to actuate a piston and frictionally engage a plate on the drum side and a friction plate on the hub side to create friction. It is known to put the engagement device into a closed state to allow torque transmission between the drum and the hub.

In order to maintain the engaged state of the conventional friction engagement device, it is necessary to continue supplying hydraulic pressure. Therefore, since a large amount of hydraulic oil is required, it is necessary to use a hydraulic oil tank and a relatively large oil pump. This is one of the factors that increase the size of the friction engagement device as a whole. In addition, the continuous supply of hydraulic oil is likely to cause a load on the oil pump and a friction loss at the seal portion. Therefore, the following has been developed.

Japanese Patent Application Laid-Open No. 2010-216501 JP 2017-133674 A

Patent Literature 1 discloses a piston structure for an automatic transmission that can maintain a frictional engagement state even if the supply of hydraulic oil is stopped after the piston is fixed. Specifically, first, when the supply of hydraulic oil is started, the first piston member is pushed by the second piston member and moves in the direction of the plate and the friction plate. When the first piston member moves to a predetermined position, the main body of the first piston member rotates and the first piston member engages with the engagement groove of the piston cover and is fixed in that state. It is said that this allows the frictional engagement state to be maintained even after the supply of hydraulic oil is stopped.

Patent Document 2 discloses a hydraulic clutch that prevents the wear of parts and maintains the frictional engagement state of the clutch while realizing a sufficient engagement load even when the supply of hydraulic oil is stopped and the hydraulic pressure is released. ing. Specifically, the movement of the piston activates a knock cam installed between the piston and the plate, and the plate and friction plate can be kept engaged even when the supply of hydraulic oil is stopped. .

However, the invention of Patent Literature 1 requires a large number of parts and the shapes of the parts are complicated, so the manufacturing cost tends to be high. Moreover, the invention of Patent Document 2 also has a problem that the number of parts is relatively large.

Accordingly, it is an object of the present invention to provide a frictional engagement device that can maintain the engaged state without continuous supply of hydraulic oil, has a small number of parts, and has high productivity.

The present invention comprises a drum, a hub, a piston, and a torque transmission mechanism for transmitting torque between the drum and the hub by operation of the piston,
A drum groove is formed in a circumferential direction on the inner surface of the drum,
The drum groove is formed in a direction that expands to one side in the axial direction, and is formed in a direction that expands to multiple sides in the axial direction with first inclined portions and second inclined portions that are alternately continuous in the circumferential direction. , comprising a plurality of third inclined portions continuous in the circumferential direction,
The first inclined portion and the second inclined portion that are adjacent in the circumferential direction form a first engagement point and a second engagement point that are axially located at different positions,
The positions of the first engagement point and the second engagement point in the circumferential direction are provided so as to face the inclined surface of the third inclined portion,
The piston has a projection that fits into the drum groove, and is biased to one side in the axial direction by a first elastic body,
By supplying hydraulic oil between the drum and the piston, the piston moves to the other side in the axial direction while compressing the first elastic body, and the projection moves along the third inclined portion. As a result, the torque transmission mechanism is operated while rotating in the circumferential direction, and when the supply of hydraulic oil is stopped, the piston is pushed back to one side in the axial direction by the repulsive force of the first elastic body. A protrusion engages the first engagement point or the second engagement point along the first or second slope, and releases the torque transmission mechanism when the protrusion engages the first engagement point. The problem is solved by a friction engagement device characterized by being configured to maintain the engagement state of the torque transmission mechanism when the second engagement point is engaged.

According to the present invention, even if hydraulic fluid is supplied to actuate the piston, the friction engagement device is brought into the engaged state, and the supply of hydraulic fluid is stopped from this state, the projection of the piston remains at the second engagement point of the drum groove. , and the engaged state of the torque transmission mechanism is maintained, so that the engaged state of the friction engagement device can be maintained without continuing to supply hydraulic oil. In addition, since the number of parts is small and the structure is simple, the frictional engagement device can be manufactured with high productivity.

Further, if a thrust bearing is arranged between the piston and the torque transmission mechanism with which the piston can come into contact, wear of the piston and the torque transmission mechanism due to the rotation of the piston can be prevented.

The torque transmission mechanism includes a drum-side spline formed on the inner surface of the drum so as to extend in the axial direction, a drum-side dog and a plurality of plates spline-fitted to the drum-side spline, and a hub. In addition, the hub-side spline extending in the axial direction, the hub-side dog continuing in the circumferential direction, and the friction plate positioned between the plates spline-fitted to the hub-side spline, move the piston to the other side in the axial direction. At this time, the drum-side dog is pushed toward the plate to bring the plate and the friction plate into frictional engagement, and the drum-side dog and the hub-side dog are fitted together. According to this configuration, the drum and the hub are rotationally synchronized by the frictional engagement between the plate and the friction plate, and the drum-side dog and the hub-side dog are easily fitted. Since the torque is transmitted, the torque transmission capacity can be increased.

Furthermore, if the second elastic body is disposed between the drum-side dog and the plate, the second elastic body is pushed toward the plate when the drum-side dog is pushed toward the plate and the frictional engagement device shifts to the engaged state. Since the plate is pushed toward the friction plate by the repulsive force of the elastic body and starts frictional engagement with the friction plate, it is possible to easily synchronize the rotation of the drum and the hub.

1 is a radial cross-sectional view of a friction engagement device of the present invention; FIG. FIG. 2 is a perspective view of a drum groove portion of the drum of FIG. 1; FIG. 2 is a radial cross-sectional view of the frictional engagement device of FIG. 1 in a transition period to an engaged state or a disengaged state; FIG. 2 is a radial cross-sectional view of the frictional engagement device of FIG. 1 in a fastened state; The figure explaining the movement in the drum groove of the protrusion of a piston. FIG. 4 is a partially enlarged view of a fitted state of a drum-side dog and a hub-side dog;

Embodiments of the present invention will be described below with reference to FIGS. However, the present invention is not limited to this embodiment.

FIG. 1 shows a friction engagement device 100 of the present invention. Since the frictional engagement device 100 basically has a symmetrical configuration with respect to the axis X, only the radial half is shown in FIG. 1 for the sake of convenience. The friction engagement device 100 includes a drum 10 , a hub 20 , a piston 30 , and a torque transmission mechanism 40 that transmits torque between the drum 10 and the hub 20 by the action of the piston 30 .

A drum-side spline 12 extending in the axial direction and a drum groove 14 (see also FIG. 2) extending in the circumferential direction are formed on the inner surface of the drum 10 . In the frictional engagement device 100, the drum-side splines 12 are provided on the inner surface of the outer circumference of the drum 10, and the drum grooves 14 are provided on the inner surface of the inner circumference. An annular first retainer 32 is rotatably attached to the inner peripheral surface of the drum 10 . Further, the annular second retainer 18 is non-rotatably disposed so as to be positioned on the side opposite to the piston 30 with respect to the first retainer 32 . The second retainer 18 is retained by a first snap ring 19 . Therefore, the first retainer 32 is retained by the second retainer 18 .

A drum-side dog 41 and a plurality of plates 42 are spline-fitted to the drum-side spline 12 . The plate 42 is retained by a second snap ring 46 . The number of plates 42 may be determined appropriately.

As shown in FIG. 5, the drum groove 14 is formed with a first inclined portion 14a and a second inclined portion 14b that are inclined in a direction of expanding toward one side (lower side in the figure) in the axial direction. The first inclined portion 14a and the second inclined portion 14b are formed so as to alternately continue in the circumferential direction. Further, a plurality of third inclined portions 14c inclined in a direction of expanding toward the other side in the axial direction (upper side in the drawing) are also formed. The third inclined portion 14c is formed so as to be continuous in the circumferential direction. The inclination and the inclination direction of the first to third inclined portions 14a to 14c may be appropriately changed as long as the operation described later can be realized.

The first inclined portion 14a and the second inclined portion 14b, which are adjacent in the circumferential direction, form a first engagement point 14d and a second engagement point 14e, respectively, which are located at different positions in the axial direction. The first engagement point 14d is located on one side in the axial direction relative to the axial position of the second engagement point 14e. Moreover, the positions of the first engagement point 14d and the second engagement point 14e in the circumferential direction are formed so as to face the radial slope of the third inclined portion 14c.

As shown in FIG. 1, the hub 20 is formed with hub-side splines 26 extending in the axial direction and hub-side dogs 24 in the circumferential direction. The hub-side dog 24 is formed so as to be located on one axial side (left side in the figure) of the hub-side spline 26 . The friction plates 22 are spline-fitted to the hub-side splines 26 so as to be positioned between the plates 42 .

The piston 30 is disposed on one side (left side in the figure) of the drum-side dog 41 in the axial direction, and has at least one projection 36 that fits into the drum groove 14 in the circumferential direction. The piston 30 is engaged with a first retainer 32 and is urged to one side (left side in the figure) in the axial direction by a first elastic body 34 that is rotatable with respect to the drum 10 . If the first elastic body 34 is a coil spring as shown, a plurality of the first elastic bodies 34 may be provided in the circumferential direction, and other elastic bodies such as disc springs may be used instead of the coil springs. When a disk spring is used as the first elastic body 34, the disk spring may be rotatably arranged with respect to the drum 10 and retained by the snap ring 19. As shown in FIG. In short, the first elastic body 34 may be configured to urge the piston 30 to one side (left side in the figure) in the axial direction. Seal members 62 and 64 are provided between the piston 30 and the drum 10 (see FIG. 3). As described above, the friction engagement device 100 has a small number of parts and a simple structure, and thus has high productivity.

Next, operation of the friction engagement device 100 will be described. 1, the projection 36 of the piston 30 is positioned at the first engagement point 14d (see FIG. 5) of the drum groove 14 when the friction engagement device 100 is in the released state. From this state, when hydraulic oil (not shown) supplied from the hydraulic oil supply passage 16 flows between the drum 10 and the piston 30, the piston 30 compresses the first elastic body 34 and moves toward the other axial side (in the drawing). to the right), resulting in the state shown in FIG. At this time, since the projection 36 of the piston 30 moves along the third inclined portion 14c of the drum groove 14, the piston 30 pushes the drum-side dog 41 toward the plate 42 while rotating in the circumferential direction. The friction plates 22 are brought into frictional engagement. As a result, the drum 10 and the hub 20 are rotationally synchronized, and the drum-side dog 41 and the hub-side dog 24 can be easily fitted. The first retainer 32 also rotates as the piston 30 rotates in the circumferential direction due to the biasing force of the first elastic body 34 .

When the hydraulic oil is further supplied, the piston 30 moves further to the other side in the axial direction (to the right in the figure) and pushes the drum-side dog 41 to engage the drum-side dog 41 with the hub-side dog 24, as shown in FIG. becomes the state shown in . More specifically, a plurality of dog teeth 48 formed in the circumferential direction of the drum-side dog 41 are fitted into the hub-side dog 24, so that the drum-side dog 41 and the hub-side dog 24 are in a fastened state (FIG. 6). reference). Thus, torque is transmitted between the drum 10 and the hub 20 by fitting the drum-side dog 41 and the hub-side dog 24, so that the torque transmission capacity can be increased. At this time, the protrusion 36 of the piston 30 has moved to the position of the third end point 14f of the third inclined portion 14c of the drum groove 14, as shown in FIG. From this state, when the supply of hydraulic oil is stopped, the piston 30 is pushed back to one side (lower side in the figure) in the axial direction by the repulsive force of the first elastic body 34, and the projection 36 of the piston 30 is inclined to the second inclination. It moves along the portion 14b and engages the second engagement point 14e. In this state, the frictional engagement state between the plate 42 and the friction plate 22 and the engagement between the drum-side dog 41 and the hub-side dog 24 are maintained, so that a large torque transmission capacity can be realized without supplying hydraulic oil. can be done.

When the frictional engagement device 100 is to be shifted from the engaged state to the disengaged state, hydraulic oil is supplied again to move the piston 30 to the other axial side (right side in the drawing). Then, the projection 36 of the piston 30 moves from the second engagement point 14e along the radial slope of the third inclined portion 14c to the position of the fourth engagement point 14g of the third inclined portion. When the supply of hydraulic oil is stopped in this state, the piston 30 is pushed back to one side (lower side in the figure) in the axial direction by the repulsive force of the first elastic body 34, and the projection 36 of the piston 30 is pushed back to the first inclined portion. 14a to the position of the first engagement point 14d. Thus, the friction engagement device 100 is in the released state shown in FIG.

Here, as shown in FIG. 1, it is preferable to dispose thrust bearings 52 and 54 between the piston 30 and the drum-side dog 41 and between the first retainer 32 and the second retainer 18, respectively. As described above, the piston 30 and the first retainer 32 rotate in the circumferential direction as the piston 30 moves in the axial direction. That is, relative rotation occurs between the piston 30 and the drum-side dog 41 and between the first retainer 32 and the second retainer 18. It is possible to prevent wear of the piston 30, the drum-side dog 41, the first retainer 32, and the second retainer 18 due to the rotation of.

A second elastic body 44 is preferably provided between the drum side dog 41 and the plate 42 . When the piston 30 is actuated and the drum-side dog 41 is pushed toward the plate 42 and the friction engagement device 100 shifts to the engaged state, the repulsive force of the second elastic body 44 pushes the plate 42 toward the friction plate 22 . , and frictional engagement with the friction plate 22 is started, so that the rotation of the drum 10 and the hub 20 can be easily synchronized. As a result, the drum-side dog 41 and the hub-side dog 24 can be easily fitted. As the second elastic body 44, an elastic body such as a coil spring or a disc spring can be used.

In the friction engagement device 100, the torque transmission mechanism 40 includes a drum-side spline 12 formed on the inner surface of the drum 10 so as to extend in the axial direction, and a drum-side dog 41 spline-fitted to the drum-side spline 12. A plurality of plates 42, an axially extending hub-side spline 26 formed on the hub 20, a hub-side dog 24 continuous in the circumferential direction, and a hub-side spline 26 spline-fitted between the plates 42. It is composed of a friction plate 22 that However, the configuration of the torque transmission mechanism 40 is not limited to this, and can be configured by, for example, a dog clutch, a plate and a friction plate, a taper cone, or a combination thereof. In short, it is sufficient that the engagement state and the disengagement state are switched by the operation of the piston 30 .

As described above, according to the present invention, it is possible to maintain the engaged state without continuously supplying hydraulic oil, and to provide a friction engagement device with a small number of parts and high productivity. .

REFERENCE SIGNS LIST 10 drum 12 drum-side spline 14 drum groove 14a first inclined portion 14b second inclined portion 14c third inclined portion 14d first engagement point 14e second engagement point 18 second retainer 20 hub 22 friction plate 24 hub-side dog 26 hub-side Spline 30 Piston 32 First retainer 34 First elastic body 36 Protrusion 40 Torque transmission mechanism 41 Drum-side dog 42 Plate 44 Second elastic body 52, 54 Thrust bearing 100 Friction engagement device

Claims (4)

a drum, a hub, a piston, and a torque transmission mechanism for transmitting torque between the drum and the hub by operation of the piston;
A drum groove is formed in a circumferential direction on the inner surface of the drum,
The drum groove is formed in a direction that expands to one side in the axial direction, and is formed in a direction that expands to multiple sides in the axial direction with first inclined portions and second inclined portions that are alternately continuous in the circumferential direction. , comprising a plurality of third inclined portions continuous in the circumferential direction,
The first inclined portion and the second inclined portion that are adjacent in the circumferential direction form a first engagement point and a second engagement point that are axially located at different positions,
The positions of the first engagement point and the second engagement point in the circumferential direction are provided so as to face the inclined surface of the third inclined portion,
The piston has a projection that fits into the drum groove, and is biased to one side in the axial direction by a first elastic body,
By supplying hydraulic oil between the drum and the piston, the piston moves to the other side in the axial direction while compressing the first elastic body, and the projection moves along the third inclined portion. As a result, the torque transmission mechanism is operated while rotating in the circumferential direction, and when the supply of hydraulic oil is stopped, the piston is pushed back to one side in the axial direction by the repulsive force of the first elastic body. A protrusion engages the first engagement point or the second engagement point along the first or second slope, and releases the torque transmission mechanism when the protrusion engages the first engagement point. and configured to maintain the engaged state of the torque transmission mechanism when engaged with the second engagement point,
Friction engagement device. 2. A frictional engagement device according to claim 1, wherein a thrust bearing is arranged between said piston and said torque transmission mechanism with which said piston is in contact. The torque transmission mechanism is
a drum-side spline formed on the inner surface of the drum so as to extend in the axial direction;
a drum-side dog and a plurality of plates spline-fitted to the drum-side spline;
an axially extending hub-side spline and a circumferentially continuous hub-side dog formed on the hub;
Composed of friction plates positioned between the plates spline-fitted to the hub-side splines,
When the piston moves to the other side in the axial direction, the drum-side dog is pushed toward the plate so that the plate and the friction plate are frictionally engaged and the drum-side dog and the hub-side dog are fitted together. 3. The frictional engagement device of claim 1 or 2, wherein 4. The friction engagement device according to claim 3, wherein a second elastic body is provided between said drum-side dog and said plate.

Images