JPS641691B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a clutch, and more particularly to a hydraulically operated clutch used as a four-wheel drive switching device in a power transmission system for a four-wheel drive vehicle.

BACKGROUND OF THE INVENTION A power transmission device for a four-wheel drive vehicle is equipped with a four-wheel drive switching device, generally called a transfer device, that selectively transmits power from a prime mover to front wheels or rear wheels, which are selective drive wheels. The four-wheel drive switching device includes a clutch.

As a clutch used in the above-mentioned four-wheel drive switching device, there is a hydraulically operated dog clutch, which is provided at mutually opposing ends of two rotating shafts provided on the same axis and has external teeth. a first clutch member and a second clutch member;
a connecting position in which the internal teeth mesh with both the external teeth of the first clutch member and the second external teeth; and a cutting position in which the internal teeth mesh only with the external teeth of the first clutch member. a clutch sleeve disposed movably in the axial direction of the rotating shaft between them, and a piston drivingly connected to the clutch sleeve, the piston moving the clutch sleeve from the disconnection position to the connection position. and a return spring that biases the piston in a direction from the connection position toward the disconnection position.

In the above-mentioned clutch, a chamfer portion is provided at the end where the inner teeth of the clutch sleeve and the outer teeth of the second clutch member mesh with each other, so that the meshing between the two can be carried out smoothly. However, if there is a relative rotational speed difference between the first clutch member and the second clutch member when the internal teeth of the clutch sleeve and the external teeth of the second clutch member mesh and engage. In this case, the internal teeth of the clutch sleeve collide with the external teeth of the second clutch member and bounce back, and the internal teeth of the clutch sleeve are pushed back against the external teeth of the second clutch member by the fluid pressure of the hydraulic cylinder device. The internal teeth of the clutch sleeve collide with the external teeth of the second clutch member and bounce back, and then the internal teeth of the clutch sleeve engage the second clutch member again. Since the speed of the member toward the external teeth depends on the speed of return of the fluid pressure of the hydraulic cylinder device, said speed is not very fast, and therefore said meshing engagement is not carried out quickly and the time lag is relatively large.

OBJECTS OF THE INVENTION In view of the above-mentioned problems with conventional hydraulically operated clutches, the present invention provides a method for quickly engaging the internal teeth of the clutch sleeve and the external teeth of the second clutch member. The purpose is to provide an improved clutch.

Structure of the Invention According to the present invention, a first clutch member and a second clutch member are provided at opposite ends of two rotating shafts provided on the same axis and have external teeth; and a connection position where the internal teeth mesh with both the external teeth of the first clutch member and the external teeth of the second clutch member, and the internal teeth mesh only with the external teeth of the first clutch member. a clutch sleeve that is movable in the axial direction of the rotary shaft between the cutting position and the clutch sleeve, a connecting member that is rotatable but fixed in the axial direction on the clutch sleeve, and a predetermined axis line on the connecting member. a hydraulic cylinder device having pistons facing each other with a directional gap and driven in a direction from the cutting position to the connecting position; and a hydraulic cylinder device provided between the connecting member and the piston to separate them from each other in the axial direction. and a return spring that urges the piston in the direction from the connecting position toward the cutting position, and the axial distance between the piston and the connecting member is This is achieved with such a clutch, which is characterized by a length shorter than the full stroke of the piston.

Effects of the Invention According to this configuration, the driving force of the fluid pressure cylinder device is transmitted to the connection sleeve via the buffer spring, and from there to the clutch sleeve.
When the internal teeth of the clutch sleeve mesh and engage with the external teeth of the second clutch member, the buffer spring is elastically deformed when the internal teeth of the clutch sleeve collide with the external teeth of the second clutch member and bounce back. , the internal teeth of the clutch sleeve advance toward the external teeth of the second clutch member again due to the repulsive force of the buffer spring, so that the speed is faster than that due to the fluid pressure of the fluid pressure cylinder device. As a result, the internal teeth of the clutch sleeve and the external teeth of the second clutch member are quickly engaged with each other.

Then, when the buffer spring is compressed by a predetermined amount because the allowable relative movement between the piston and the connecting member in the axial direction, that is, the allowable relative movement amount in the axial direction between the two is shorter than the full stroke of the piston, the piston moves into the connecting member. Since the inner teeth and the outer teeth come into direct contact with each other and directly drive them, torque is transmitted between the inner teeth and the outer teeth, and the tooth flanks of the two teeth engage with each other. Due to the pressing, the axial movement of the clutch sleeve and thus the connecting member is ensured, even if the drive force required for the axial movement increases, and it is ensured that the clutch sleeve is located in the correct clutch engagement position.

DESCRIPTION OF EMBODIMENTS The invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

The attached figure is a longitudinal sectional view showing one embodiment of the dog clutch according to the present invention as a four-wheel drive switching device of a vehicle power transmission device. In the figure,
1 indicates an extension housing.
The extension housing 1 has a connecting shaft 2 and a rear wheel drive shaft 3, which are drivingly connected to the end of an output shaft of a gear transmission (not shown), on the central axis inside the extension housing 1.
It has

The connecting shaft 2 has an end shaft portion 4 that engages with a bearing hole 5 extending in the axial direction at one end of the rear wheel drive shaft 3, and the end shaft portion is rotated by the rear wheel drive shaft 3. The rear wheel drive shaft 3 is rotatably supported by the extension housing 1 by means of a radial ball bearing 6.

The connecting shaft 2 integrally has a clutch member (second clutch member) 8 having external teeth 7 at an end adjacent to the one end of the rear wheel drive shaft 3. The rear wheel drive shaft 3 integrally has a clutch member (first clutch member) 10 having external teeth 9 at one end thereof.
The outer teeth 7 and 9 are concentric with each other and have pitch circles of the same diameter, and the outer teeth 9 have a clutch sleeve 11.
The inner teeth 12 of the two are in mesh with each other. clutch sleeve 1
1 is movable in the axial direction of the rear wheel drive shaft 3 between a cutting position where the internal teeth 12 mesh only with the external teeth 9 and a connecting position where the internal teeth 12 mesh with both of the external teeth 9 and 7. The connecting shaft 2 and the rear wheel drive shaft 3 are connected in a rotational power transmission relationship when the connecting shaft is moved to the left in the figure from the position shown in the figure and is in the connecting position. .

Chamfer portions 12a and 7a are provided at the ends of the meshing engagement between the internal teeth 12 of the clutch sleeve 11 and the external teeth 7 of the clutch member 8, respectively.

An inner race 22a of a radial ball bearing 22 is fixed to the outer periphery of the clutch sleeve 11 by being sandwiched between the flange 11a of the clutch sleeve 11, a collar 29, and a snap ring 30. The outer race 22b of the radial ball bearing 22 is attached to the connecting sleeve (connecting member) 18 fitted to the outer periphery of the outer race, and the locking piece 18b of the connecting sleeve
and a snap spring 31 for a fixed connection. That is, the connecting sleeve 18 is attached to the clutch sleeve 11 by means of a radial ball bearing 22 so as to be rotatable but fixed in the axial direction.

The extension housing 1 defines an annular cylinder bore 13 concentric with the connection shaft 2 and the rear wheel drive shaft 3 inside thereof by an outer cylinder part 1a and an inner cylinder part 1b which are concentric with each other. An annular piston 14 is engaged to be movable in the axial direction. The piston 14 defines a cylinder chamber 17 on one side, that is, on the side of the clutch member 10 relative to the clutch member 8 (on the right side in the figure), which is made fluid-tight by oil seals 15 and 16. The piston 14 has a protruding portion 14a on the other side that protrudes in the axial direction from the inner cylinder portion 1b, and the protruding portion is in sliding contact with the outer circumferential portion of the connecting sleeve 18 at the inner circumferential portion so as to be movable in the axial direction. Further, an annular stopper plate 20 is fixed to the tip of the protrusion with bolts 19. The piston 14 has a projection 14d that engages with an axial groove 1c provided in the extension housing 1, and the piston is prevented from rotating by the engagement between the projection 14d and the groove 1c.

The stopper plate 20 partially has a portion in the circumferential direction that faces the end of the piston 14 at a predetermined interval in the axial direction and defines a gap, and the stopper plate 20 has a portion that faces the end of the piston 14 at a predetermined interval in the circumferential direction. A flange piece 18a that partially extends from the connecting sleeve 18 in the circumferential direction is located in the gap between the connecting sleeves 18 and 18 so as to be movable in the axial direction. A buffer compression coil spring 21 is disposed with a predetermined preload between the flange piece 18a and the bottom of the bottomed hole 14b provided in the piston 14. and the connecting sleeve 18 are urged away from each other in the axial direction. That is, the piston 14 and the connecting sleeve 18 are configured to be able to move relative to each other by a predetermined distance in the axial direction against the spring force of the buffer compression coil spring 21. The permissible relative movement _S1 in the axial direction between the piston 14 and the connecting sleeve 18 is smaller than the total stroke _S2 of the piston 14, and when the buffer compression coil spring 21 is compressed by a predetermined amount, the piston 14 moves at its tip. Flange piece 18 of connection sleeve 18
It is designed so that it can directly contact a and drive it directly to the left in the figure.

In order to absorb misalignment between the piston 14 and the rear wheel drive shaft 3, a radial gap 25 is provided at the fitting portion between the inner race 22a of the radial ball bearing 22 and the clutch sleeve 11.

An annular spring retainer 2 is installed inside the extension housing 1 by a snap spring 32.
3 is fixed. A return compression coil spring 24 is attached with a predetermined preload between the spring retainer 23 and the bottom of the bottomed hole 14c provided in the piston 14. The return compression coil spring 24 urges the piston 14 to the right in the figure, that is, in a direction from the connection position toward the disconnection position. The return compression coil spring 24 is made of a spring weaker than the buffer compression coil spring 21, and its preload is smaller than the preload of the buffer compression coil spring 21.

Next, the operation of the clutch constructed as described above will be explained.

FIG. 1 shows a state in which no oil pressure is supplied to the cylinder chamber 17, and the clutch sleeve 11, together with the piston 14 and the connecting sleeve 18, is in the disconnected position on the right side of the figure. In this state, when hydraulic pressure is supplied to the cylinder chamber 17, the piston 14 moves to the left in the figure against the spring force of the return compression coil spring 24, and accordingly, the buffer compression coil spring 21 , the clutch sleeve 11 together with the connecting sleeve 18 and the radial ball bearing 22 is moved axially to the left in the figure, ie towards the clutch member 8 . When the chamfer part 12a of the internal tooth 12 collides with the chamfer part 7a of the internal tooth 7 of the clutch member 8 due to the axial movement of the clutch sleeve 11, the clutch sleeve 11 cannot move any further to the left in the figure, whereas the piston 14 is subsequently moved to the left in the figure by the hydraulic pressure supplied to the cylinder chamber 17, so that the piston 14 moves to the other side in the figure with respect to the connecting sleeve 18 while compressing the buffer compression coil spring 21. When the clutch sleeve 11 rebounds due to the collision of the chamfer part 12a of the internal teeth 12 of the clutch sleeve 11 with the chamfer part 7a of the external teeth 7 of the clutch member 8, the axial direction The connecting sleeve 18 which is immovably connected to the buffer compression coil spring 21
It moves to the right in the figure with respect to the piston 14 while compressing it. When the chamfer part 12a of the internal teeth 12 of the clutch sleeve 11 and the chamfer part 7a of the external teeth 7 of the clutch member 8 engage with each other due to the relative rotation between the connecting shaft 2 and the rear wheel drive shaft 3, they are compressed and deformed. Due to the spring force of the buffer compression coil spring 21, the clutch sleeve 11 moves to the left in the figure at high speed together with the connecting sleeve 18 and the radial ball bearing 22.
The meshing engagement between the internal teeth 12 and the external teeth 7 is performed. When the internal teeth 12 and the external teeth 7 mesh and engage, the connecting shaft 2
The rotational power is transmitted to the clutch sleeve 11 through the meshing portion between the external teeth 7 and the internal teeth 12,
2 and the external teeth 9, the clutch sleeve 11
is transmitted to the rear wheel drive shaft 3.

Even after the transmission of rotational power has started through the clutch sleeve 11 as described above, the clutch sleeve 11 is driven to the left in the figure in order to complete the engagement between the internal teeth 12 and the external teeth 7. The clutch sleeve 1 is pressed against the internal teeth 12 and the external teeth 7 by the rotational power transmitted from the connecting shaft 2 to the rear wheel drive shaft 3 via the clutch sleeve 11.
The driving force required to move 1 to the left in the figure increases. Therefore, at this time, the piston 14 is
While compressing the buffer compression coil spring 21, it moves to the left in the figure with respect to the connection sleeve 18, and the permissible relative movement amount between the piston 14 and the connection sleeve 18.
Since S ₁ is smaller than the total stroke S ₂ of the piston 14, the piston directly contacts the flange piece 18a of the connecting sleeve 18 with its tip end surface, and directly drives the connecting sleeve 18 to the left in the figure. As a result, the clutch sleeve 11 is driven to the left in the figure together with the radial ball bearing 22, and the clutch sleeve 11 is positioned at the connection position, and the engagement between the internal teeth 12 and the external teeth 7 is completed.

In order to move the clutch sleeve 11 in the connected position to the disconnected position, ie, to disengage the clutch, the hydraulic pressure supplied to the cylinder chamber 17 only needs to be discharged. When the hydraulic pressure in the cylinder chamber 17 is discharged, the piston 14 moves to the right in the figure by the spring force of the return compression coil spring 24, and the connecting sleeve 18 is moved to the right in the figure by the stopper plate 20. As a result, the clutch sleeve 1 along with the radial ball bearing 22
1 moves to the right in the figure, and the internal teeth 12 are separated from the engagement with the external teeth 7 of the clutch member 8.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto, and various other embodiments are possible within the scope of the present invention. This will be clear to those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment in which the clutch according to the present invention is applied as a four-wheel drive switching device of a vehicle power transmission device, and FIG. 2 is a diagram showing the piston and connecting sleeve of the clutch shown in FIG. 1. FIG. 3 is an exploded perspective view of the stopper plate and the stopper plate. DESCRIPTION OF SYMBOLS 1... Extension housing, 2... Connection shaft, 3... Rear wheel drive shaft, 4... End shaft part, 5... Bearing hole,
6... Radial ball bearing, 7... External tooth, 8... Clutch member, 9... External tooth, 10... Clutch member, 11...
Clutch sleeve, 12...Internal teeth, 13...Cylinder bore, 14...Piston, 15, 16...Oil seal, 17...Cylinder chamber, 18...Connection sleeve, 1
9... Bolt, 20... Stopper plate, 21... Buffer compression coil spring, 22... Radial ball bearing, 23... Spring retainer, 24... Return compression coil spring, 25... Gap, 29... Collar, 30-3
2...Snat Spring.

Claims (1)

[Claims] 1 A first clutch member and a second clutch member each having external teeth and provided at mutually opposing ends of two rotating shafts provided on the same axis; in the axial direction of the rotating shaft between a connecting position where the clutch member meshes with both the external teeth of the second clutch member and a cutting position where the clutch member meshes with only the external teeth of the first clutch member. a clutch sleeve movably disposed on the clutch sleeve; a connecting member rotatable but fixed in the axial direction on the clutch sleeve; a hydraulic cylinder device having a piston driven in a direction toward the connection position; a buffer spring provided between the connection member and the piston to urge them apart from each other in the axial direction; and the piston. and a return spring biasing the piston from the connecting position toward the cutting position, and the distance between the piston and the connecting member in the axial direction is shorter than the entire stroke of the piston. Clutch.