JP2003322178A - Driving force distributing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force distributing device for transmitting a driving force when the number of rotations of an outer rotating member is more than the number of rotations of an inner rotating member, but not transmitting the driving force in an adverse case. <P>SOLUTION: The inner rotating member 22 is coaxially rotatably supported on the outer rotating member 21, a frictional clutch 25 for connecting the rotating members is engaged by a pressure force generating means 30 utilizing fluid pressure generated by rotating a rotor 32 held on the inner rotating member in an annular chamber 33 formed on the outer rotating member side and including a viscous fluid. A two-way clutch 35 holding a rotor on the inner rotating member is configurated by mounting a ball 37 between a plurality of recessed cam faces 36 formed on the inner peripheral face 32c of the rotor and having engagement slopes on its both sides in the circumferential direction, and the outer peripheral face of the inner rotating member, and the ball is held by a holding hole 38a formed in a ball guide 38 slidably fitted to the inner peripheral face of the rotor. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force distribution device suitable for being installed in a power transmission path connecting front and rear wheels of a real-time four-wheel drive vehicle.

[0002]

2. Description of the Related Art As a driving force distribution device of this type, there is a technique disclosed in, for example, Japanese Unexamined Patent Publication No. Hei 7-132747. This is a cylindrical housing (outer rotating member), an inner shaft (inner rotating member) rotatably supported by the housing coaxially, and a housing provided between the inner shaft and the inner shaft. The transmission torque between the pressing force generating means for generating a pressing force according to the increase of the rotational speed and the transmission torque between the both in accordance with the increase of the pressing force generated by the pressing force generating means provided between the inner shaft of the housing And a pressing piston that is slidably provided in the housing so that one side surface contacts the friction clutch, and the other side surface of the pressing piston and the housing. And a rotor having a blade portion that is directly connected to the inner shaft and that rotates in a viscous fluid enclosed in the annular chamber.

The blade portion of the rotor rotates in the annular chamber according to the relative rotation speed between the housing and the inner shaft to force the viscous fluid to flow, and the fluid pressure generated thereby causes the pressing piston to move. Since the friction clutch is pressed, the torque transmitted between the housing and the inner shaft increases as the relative rotational speed between the two increases. The change characteristics of the transmission torque with respect to the relative rotation speed are the same when the rotation speed of the housing is higher (thus, the torque is transmitted from the housing side to the inner shaft side) and vice versa. By disposing such a driving force distribution device so that the housing is on the front wheel side and the inner shaft is on the rear wheel side, and connecting the rear wheel to the front wheel driven by the engine (see FIG. 6), it is possible to prevent muddyness and the like. A real-time four-wheel drive vehicle with high traction performance when escaping from a rough road can be obtained.

[0004]

ABS for automobiles
(Anti-skid brake system) and VSC (Vehicle Safety Control) are available with brake control devices. When such a brake control device is activated, the speed of the rear wheels is often lower than the rotation speed of the rear wheels. Is also controlled so that the rotation speed of the front wheels becomes smaller.
When the front and rear wheels of an automobile equipped with such a brake control device are connected by the power transmission path equipped with the drive force distribution device as described above to form a real-time four-wheel drive vehicle, the brake control device operates. In this case, the driving force distribution device prevents the action of making the rotation speed of the front wheels smaller than the rotation speed of the rear wheels, so that the brake control device does not function sufficiently.

According to the present invention, when the rotation speed of the outer rotating member (housing) becomes smaller than the rotation speed of the inner rotating member (inner shaft), the friction clutch is not engaged, and such a problem is solved. The purpose is to resolve.

[0006]

To this end, a drive force distribution device according to the present invention is provided with an outer rotary member, an inner rotary member coaxially rotatably supported by the outer rotary member, and both rotary members. For increasing the pressing force generated by the pressing force generating means provided between the rotating members and the pressing force generating means for generating the pressing force according to the increase in the relative rotational speed between the rotating members. Accordingly, a friction clutch for increasing the torque transmitted between the two rotating members is provided, and the pressing force generating means is coaxially slidably fitted in the outer rotating member so that one side surface presses the friction clutch. A pressure piston arranged in
An annular chamber formed between the other side surface of the pressing piston and the outer rotating member, and a blade that rotates in a viscous fluid that is connected to the inner rotating member and is enclosed in the annular chamber to generate a fluid pressure that operates the pressing piston. In a driving force distribution device including a rotor having a portion, the rotor is connected to the inner rotating member via a two-way clutch.

The two-way clutch of the driving force distribution device described in the preceding paragraph has a plurality of concave cam surfaces formed on the inner peripheral surface of the rotor and having engaging slopes on both sides in the circumferential direction, and the concave cam surfaces and the inner rotation. It is preferable that it comprises a ball arranged between the outer peripheral surfaces of the members and a ball guide formed with a plurality of holding holes slidably fitted to the inner peripheral surface of the rotor to hold the balls. .

The holding hole of the ball guide of the driving force distribution device described in the preceding paragraph is shaped so as to generate a force for pressing the ball against the outer peripheral surface of the inner rotating member when the ball moves in the circumferential direction with respect to the ball guide. It is preferable.

It is preferable that the ball guide of the driving force distribution device described in the above item 2 is arranged at a position shifted outward in the radial direction of both rotary members from the center of each ball.

It is preferable that the holding hole of the ball guide of the driving force distribution device described in the preceding paragraph 3 has an elongated shape in the circumferential direction of the ball guide.

[0011]

When the outer rotating member starts to rotate while both rotating members are stopped, the rotor having the blade portion first starts to rotate together with the outer rotating member due to the viscosity of the viscous fluid. The two-way clutch locks the inner rotating part and stops it. Then,
The rotor rotates relative to the outer rotating member, and the blade portion rotates in the annular chamber to forcibly flow the viscous fluid inside the rotor.The fluid pressure generated by this causes the pressing piston to move and press the friction clutch. To engage this,
Transmission of torque from the outer rotating member to the inner rotating member is started.

When the rotation speed of the outer rotating member is higher than that of the inner rotating member, the inner rotating member and the rotor are locked by the two-way clutch as described above, and the torque is transmitted from the outer rotating member to the inner rotating member. However, if a reverse driving force from the inner rotating member side occurs and the number of rotations of the inner rotating member becomes higher than that of the outer rotating member, the two-way clutch locks the rotor and the inner rotating member. When the rotor is released, the rotor rotates together with the outer rotating member due to the viscosity of the viscous fluid, the pressing force of the pressing piston becomes zero, and the engagement of the friction clutch is released. As described above, when the rotation speed of the inner rotating member is higher than the rotation speed of the outer rotating member, the transmission force of the friction clutch is zero.
Therefore, torque is not transmitted from the inner rotating member to the outer rotating member regardless of the difference in the number of rotations of both rotating members.

As described above, in the driving force distribution device according to the present invention, when the rotation speed of the outer rotating member is higher than the rotation speed of the inner rotating member, the friction clutch is engaged and the inner rotating member moves from the outer rotating member side. Torque is transmitted to the side, but when the rotation speed of the outer rotating member becomes lower than the rotation speed of the inner rotating member, the friction clutch is disengaged from the inner rotating member side to the outer rotating member side. Is not transmitted.

The driving force distribution device of the present invention is arranged such that the outer rotary member is on the front wheel side and the inner rotary member is on the rear wheel side, and the rear wheel is connected to the front wheel driven by the engine. Thus, it is possible to obtain a real-time four-wheel drive vehicle that has high traction performance when escaping from a rough road such as a muddy road, and that does not hinder the function of the brake control device.

The two-way clutch is arranged between the plurality of concave cam surfaces formed on the inner peripheral surface of the rotor and having engaging slanting surfaces on both sides in the circumferential direction, and the outer peripheral surface of the inner rotating member. According to the driving force distribution device, which is composed of a ball and a ball guide in which a plurality of holding holes for holding each ball are formed so as to be slidably fitted to the inner peripheral surface of the rotor, The two-way clutch locks the rotor with respect to the inner rotating member by the ball biting between one of the engaging slopes on both sides and the outer peripheral surface of the inner rotating member. When the reverse driving force is generated from the inner rotating member side and the rotation speed of the inner rotating member becomes higher than the rotation speed of the outer rotating member, the ball is attached to one of the engaging slopes of the concave cam surface of the rotor and the inner rotating member. The lock by the two-way clutch is released by being released from between the outer peripheral surfaces of. In this state, the ball guide that holds each ball moves along with the rotor due to the friction with the inner surface of the rotor and the viscosity of the viscous fluid, so each ball stays near the engaging slope that had been biting up to then and moves immediately. It does not cut into the engaging slope on the opposite side. Therefore, the period in which the torque is not transmitted from the inner rotating member to the outer rotating member continues for a considerable period, and when the rotation speed of the outer rotating member becomes higher than the rotation speed of the inner rotating member again, the inner rotating member moves from the outer rotating member side. The torque transmission to the side is performed without time delay.

According to the driving force distribution device, the holding hole of the ball guide is shaped so as to generate a force for pressing the ball against the outer peripheral surface of the inner rotating member when the ball moves in the circumferential direction with respect to the ball guide. When the rotating member begins to rotate, the ball is first pressed and held against the outer peripheral surface of the inner rotating member by the holding hole of the ball guide that rotates with the rotor, and then abuts on one engaging slope of the concave cam surface. The two-way clutch locks the rotor with respect to the inner rotating member. As described above, since the ball is first held on the outer peripheral surface of the inner rotating member, the two-way clutch locks quickly and reliably, and torque transmission from the outer rotating member side to the inner rotating member side is performed without time delay. .

By arranging the ball guides at positions shifted outward in the radial direction of both rotary members from the center of each ball, even if the holding hole formed in the ball guide has a simple constant sectional shape, On the other hand, if the ball moves in the circumferential direction, a force that presses the ball against the outer peripheral surface of the inner rotating member is generated, so that the shape of the ball guide can be simplified and the productivity can be improved.

According to the driving force distribution device in which the holding hole of the ball guide is elongated in the circumferential direction of the ball guide, when the ball moves in the circumferential direction with respect to the ball guide by changing the shape of the holding hole. Further, since the force pressed against the outer peripheral surface of the inner rotating member can be easily adjusted, the pressing force of the ball against the outer peripheral surface of the inner rotating member can be adjusted to perform the locking by the two-way clutch more quickly and reliably.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A driving force distribution device according to the present invention will be described below with reference to the embodiments shown in FIGS. The driving force distribution device 20 of this embodiment is provided in a housing (outer rotating member) 21, an inner shaft (inner rotating member) 22 coaxially rotatably supported by the housing 21, and in the housing 21. It also comprises a friction clutch 25 and a pressing force generating means 30.
This driving force distribution device 20 is, for example, as shown in FIG.
It is used when the housing 21 is arranged so that the front wheel 13 side is located and the inner shaft 22 is located on the rear wheel 17 side, and the rear wheel 17 is coupled to the front wheel 13 driven by the engine 10.

As shown in FIGS. 1 and 2, the housing 21 has a cylindrical outer case 2 with one end closed.
1a and an end cover 21b screwed and fixed to the inner surface on the opening side of the outer case 21a, and the fitting portion between the outer case 21a and the end cover 21b is liquid-tightly sealed by an O-ring. Both ends of the inner shaft 22 are rotatably supported by the bottom of the outer case 21a and the inner surface of the center hole of the end cover 21b via ball bearings and needle bearings, and the end cover 21b is more than the spline shaft portion described later.
The outer peripheral surface of the cylindrical portion of the inner shaft 22 on the side and the inner surface of the end cover 21b are fluid-tightly and rotatably sealed by an O-ring. A shallow circular recess 23 is formed on the inner end surface of the end cover 21b on the friction clutch 25 side except the peripheral portion, and the central portion of the recess 23 around the center hole is deepened in a stepwise manner.

As shown in FIG. 1, a friction clutch 25 for transmitting torque between the housing 21 and the inner shaft 22 is a wet multi-plate in which seven friction plates 26 and six clutch plates 27 are alternately stacked. It is a clutch, and friction plates 26 are located on both outer sides in the axial direction. An outer peripheral edge of each friction plate 26 is axially movably engaged with a spline hole formed in the inner half of the inner peripheral surface of the outer case 21a so as to rotate together with the outer case 21a. There is. The inner peripheral edge of each clutch plate 27 is axially movably engaged with a spline shaft portion formed on the outer periphery of the inner shaft 22 in correspondence with the spline hole, and is rotated together with the inner shaft 22. There is.

The pressing force generating means 30 generates a pressing force that increases in accordance with an increase in the relative rotational speed between the housing 21 and the inner shaft 22, and mainly as shown in FIGS. 1 and 2, the pressing piston 31. The rotor 32, the annular chamber 33, and the two-way clutch 35.
The pressing piston 31 has an annular shape, the outer peripheral surface of which is fitted in a liquid-tight and slidable manner via an O-ring to the inner peripheral surface of the outer case 21a which is closer to the end cover 21b than the spline hole portion, and the inner peripheral surface is splined. End cover 21b rather than shaft
It is fitted to the outer peripheral surface of the cylindrical portion of the inner shaft 22 on the side (hereinafter simply referred to as the outer peripheral surface of the inner shaft 22) via an O-ring in a liquid-tight and slidable manner. One end surface of the pressing piston 31 can come into contact with the outermost friction plate 26, and the other end surface in the free state is a disc spring interposed between the pressing piston 31 and the inner rotating member 22, and the outer edge of the inner end surface of the end cover 21b. It is designed to be lightly abutted on the part.

As shown in FIGS. 1 and 2, the annular chamber 33 includes an inner end surface of the end cover 21b having a circular recess 23, another end surface of the pressing piston 31, and an outer peripheral surface of the inner shaft 22. The O-rings formed between the end covers 21b and the inner and outer circumferences of the pressing piston 31 are liquid-tightly shielded from the outside. A two-way clutch 35, which will be described in detail later, is provided in the annular chamber 33.
A boss portion 32a engaged with and supported by the cylindrical portion of the inner shaft 22 via a pair of blade portions 32b formed integrally with the boss portion 32a and extending radially outwardly and symmetrically.
The rotor 32 is made of a rotating material.
A viscous fluid having a high viscosity such as silicon oil is enclosed together with a small amount of air in an annular chamber 33 provided with the rotor 32 and the two-way clutch 35. When the rotor 32 rotates with respect to the housing 21 and the blade portion 32b forces the viscous fluid in the annular chamber 33 to flow, the fluid pressure generated thereby moves the pressing piston 31 to press the friction clutch 25. This is engaged.

As shown in FIGS. 1 to 4, the two-way clutch 35 has eight concave cam surfaces 36 formed on the inner peripheral surface 32c of the rotor 32 and having engaging slopes on both sides in the circumferential direction.
Eight balls 37 arranged between each concave cam surface 36 and the outer peripheral surface of the inner shaft 22, and eight balls 37 slidably fitted to the inner peripheral surface 32c of the rotor 32 to hold each ball 37. Ring-shaped ball guide 3 having a holding hole 38a
It consists of 8. The distance between the outer peripheral surface of the inner shaft 22 in the vicinity of the center of each concave cam surface 36 is slightly larger than the diameter of each ball 37. Therefore, when the balls 37 are in the vicinity of the center of the concave cam surface 36, the rotor 32 is not formed. Is rotatable with respect to the inner shaft 22, but the ball 37
Is moved in the circumferential direction to come into contact with either one of the engaging slopes, the rotor 32 is locked in rotation in one direction corresponding to the contacting engaging slope. Each holding hole 38a of the ball guide 38
The position where each of the balls 37 abuts is farther to the outer peripheral side than the center point of each ball 37 with respect to the center line of the inner shaft 22 (see FIG. 3), and each holding hole 38 a is in the circumferential direction of the ball guide 38. Has an elongated elliptical shape in FIG.
Therefore, when the ball 37 moves in the circumferential direction with respect to the ball guide 38, it is pressed against the outer peripheral surface of the inner shaft 22.

FIG. 6 shows the driving force distribution device 20 described above.
It is a figure which shows an example at the time of applying to a real-time type four-wheel drive vehicle. The driving force from the engine 10 is transmitted to a transfer 12 via a transaxle 11 provided with a transmission, and the driving force distributed to the front wheels is transmitted to the left and right front wheels 13 via a front differential (not shown). Further, the driving force distributed to the rear wheels is provided by a propeller shaft 15 provided with a driving force distribution device 20 on the way.
And left and right rear wheels 17 via the rear differential 16
Be transmitted to. Housing 21 of driving force distribution device 20
Is coaxially bolted to the rear end of the input shaft 15a on the engine 10 side of the propeller shaft 15, and the inner shaft 22 has its spline hole 22a connected to the front end of the output shaft 15b on the rear wheel 17 side. See also Figure 1).

Next, the operation of the driving force distribution device 20 described above will be described. Housing 21 and inner shaft 22
Is stopped and the ball 37 is near the center of the concave cam surface 36 as shown in FIG. 5 (a), as described above,
The relative rotation between the inner shaft 22 and the rotor 32 is free. When the housing 21 on the input side starts to rotate in one direction from this stopped state, the rotor 32 is also dragged by the viscosity of the viscous fluid in the annular chamber 33 and starts to rotate together with the housing 21, but the stopped two-way clutch. Because the ball 37 of 35 tries to stay in that position due to inertia, it approaches one of the engaging slopes of the concave cam surface 36 as shown in FIG. 5 (b), and then this engagement as shown in FIG. 5 (c). The rotor 32 comes into contact with the inclined surface and bites into the outer peripheral surface of the inner shaft 22 on the output side (stopped), and the rotor 32 is locked by the inner shaft 22 by the two-way clutch 35 and temporarily stops. Then, the rotor 32 rotates with respect to the housing 21 and the blade portion 32b moves into the annular chamber 33.
The viscous fluid inside is forced to flow, and the fluid pressure generated by this causes the pressing piston 31 to move, causing the friction clutch 25 to move.
Is pressed to engage it, and torque is started to be transmitted from the housing 21 to the inner shaft 22. As a result, the inner shaft 22 starts to rotate, and the rotor 32 and the balls 37 also rotate integrally with the inner shaft 22. However, if the number of rotations of the housing 21 and the inner shaft 22 is the same, the rotor 3 is
Since the blade portion 32c of 2 does not rotate, the pressing piston 3
The force of pressing the friction clutch 25 by 1 becomes 0. As the rotation speed of the inner shaft 22 is lower than the rotation speed of the housing 21 and the difference between the rotation speeds is increased, the pressing force of the pressing piston 31 is increased and the torque transmission force from the housing 21 to the inner shaft 22 is increased.

For some reason, a reverse driving force is generated from the output side, and the rotation speed of the inner shaft 22 is changed to the housing 2.
If the number of revolutions is higher than 1, the rotor 32 will rotate together with the housing 21 due to the viscosity of the viscous fluid.
As shown in (d), the ball 37 is disengaged from one of the engaging slopes of the rotor 32, and the rotor 32 is unlocked from the inner shaft 22 by the two-way clutch 35. Therefore, the blade portion 3 with respect to the housing 21
In this state in which 2c does not rotate, the pressing force of the pressing piston 31 is 0 and the transmission force of the friction clutch 25 is also 0.
Torque is not transmitted from the inner shaft 22 to the housing 21 regardless of the difference in both rotational speeds.

In this state, if the ball 37 moves and one of the balls 37 bites between the other engagement slope of the rotor 32 and the inner shaft 22, torque is transmitted from the inner shaft 22 to the housing 21. However, since the two-way clutch 35 of this embodiment is provided with the ball guide 38, such a situation does not occur. That is, when the rotation speed of the inner shaft 22 is higher than the rotation speed of the housing 21 and each ball 37 of the two-way clutch 35 is out of the engagement with one of the engaging slopes, a holding hole for holding each ball 37. The ball guide 38, on which the rotor 38a is formed, is rotated by the frictional resistance with the inner surface of the rotor 32 and the viscosity of the viscous fluid.
Since each ball 37 takes a long time to move to a position away from the engagement slope which has been engaged until then, it immediately abuts the other engagement slope and contacts the inner engagement slope with the inner slope. There is no bite between the shafts 22 and therefore no torque is transmitted from the inner shaft 22 to the housing 21. When the rotation speed of the housing 21 becomes higher than the rotation speed of the inner shaft 22 again, the torque transmission from the housing 21 to the inner shaft 22 is started without a time delay. As described above, the two-way clutch 35, when rotating in one direction, is
When the rotation speed of the inner shaft 22 is higher than that of the inner shaft 22, the rotation is immediately transmitted from the rotor 32 to the inner shaft 22, but when the rotation speed of the inner shaft 22 is higher, the rotation of the inner shaft 22 to the rotor 32 is increased. Is transmitted only after a certain amount of time has passed.

Further, in the above-described embodiment, the position where each holding hole 38a of the ball guide 38 abuts each ball 37 is set to a position farther from the center point of each ball 37 with respect to the center line of the inner shaft 22. The holding hole 38a has an elongated elliptical shape in the circumferential direction of the ball guide 38 so that the ball 37 can be pressed against the outer peripheral surface of the inner shaft 22 when the ball 37 moves in the circumferential direction with respect to the ball guide 38. For example, when the rotor 32 is locked to the inner shaft 22 by the two-way clutch 35, the balls 37 are first pressed and held by the inner shaft 22 by moving with respect to the ball guide 38, and then the one of the concave cam surfaces 36. Ball 3 with engaging slope
Upon hitting 7, the rotor 32 is locked to the inner shaft 22. Accordingly, the locking of the rotor 32 with respect to the inner shaft 22 and the accompanying torque transmission from the housing 21 to the inner shaft 22 are reliably performed in a short time. However, the present invention is not limited to this, and the present invention may be carried out with each holding hole 38a of the ball guide 38 only holding each ball 37 at a predetermined position.

The holding hole 3 as in the above-described embodiment.
If 8a is elongated in the circumferential direction of the ball guide 38, the shape of the holding hole 38a is changed to press the ball 37 against the outer peripheral surface of the inner shaft 22 when the ball 37 moves in the circumferential direction with respect to the ball guide 38. Since the applied force can be easily adjusted, slippage of the ball 37 with respect to the outer peripheral surface of the inner shaft 22 can be reduced and the two-way clutch 35 can be locked more quickly and reliably. Further, by disposing the ball guides 38 at positions displaced from the center of each ball 37 outward in the radial direction of both rotary members, even if the holding hole 38a formed in the ball guide 38 has a simple constant cross-sectional shape, On the other hand, when the ball 37 moves in the circumferential direction, a force for pressing the ball 37 against the outer peripheral surface of the inner shaft 22 is generated, so that the shape of the ball guide 38 can be simplified. However, the present invention is not limited to this, and the center of each ball is positioned within the range of the wall thickness of the ball guide, and the holding hole 38a is a tapered hole whose outside becomes smaller, and the holding hole 38a is formed.
It is also possible to generate a force that presses the ball 37 against the outer peripheral surface of the inner shaft 22 such that the position where the ball 37 contacts the ball 37 is farther from the center point of the ball 37 with respect to the center line of the inner shaft 22.

Housing 21 and inner shaft 22
The above operation is performed in the same manner even when is rotated in the opposite direction. However, in the first operation in which the rotation direction is switched to the opposite direction, it takes some time for the ball 37 to bite between the other engagement slope and the inner shaft 22, so the friction clutch 25 is engaged. Then, a slight time lag occurs before the torque is transmitted from the housing 21 to the inner shaft 22. Two-way clutch 3
In the case of the reverse rotation, as in the case of the unidirectional rotation described above, 5 immediately transmits the rotation from the rotor 32 to the inner shaft 22 when the rotation speed of the rotor 32 becomes higher. However, when the rotation speed of the inner shaft 22 becomes higher,
The rotation is not transmitted to 2 until some time has passed.

In the embodiment described above, the torque transmitted by the friction clutch 25 between the housing 21 and the inner shaft 22 increases only in accordance with the increase in the relative rotational speed between the two 21, 22 and, therefore, the housing 21. The drive force distribution device 20 in which slippage is always accompanied between the inner shaft 22 and the inner shaft 22 has been described, but the present invention is not limited to this.
A driving force distribution device is provided with a lock-up mechanism that engages the friction clutch 25 without slippage by a cam means that generates thrust force by transmission torque, and allows the housing 21 and the inner shaft 22 to engage without slippage depending on the operating state. Can also be applied.

Further, in the above-described embodiment, the rotor 32
The pair of blade portions 32b are symmetrically extended outward in the radial direction, but the present invention is not limited to this, and the blade portions may be in the shape of a disc having irregularities on the surface. Further, in order to eliminate the misalignment of the rotor 32 with respect to the inner shaft 22,
A ring that slidably fits on the inner peripheral surface of the ball guide 38 and the outer peripheral surface of the inner shaft 22 may be provided on one side or both sides of the ball 37.

Further, in the above-described embodiment, the rotor 32
The two-way clutch 35 is formed by the ball 37, the ball guide 38 and the concave cam surface 36 which are arranged between the inner circumference of the inner shaft 22 and the outer circumference of the inner shaft 22. The rotation (both left and right) is transmitted to the output member side, but the rotation from the output member side is not transmitted to the input member side.

As shown in FIG. 6, the driving force distribution device 20 is arranged so that the housing 21 is on the front wheel 13 side and the inner shaft 22 is on the rear wheel 17 side.
If the rear wheels 17 are connected to the front wheels 13 driven by 0,
When the front wheels 13 slip on a bad road such as a muddy road in a normal operating state, the rotation speed of the housing 21 becomes higher than the rotation speed of the inner shaft 22, and the driving force distribution device 20
The transmission torque due to
Since the distribution ratio of the driving force to the vehicle increases, the traction performance for escaping from a bad road such as a muddy road becomes higher. Further, when the rotation speed of the housing 21 becomes lower than the rotation speed of the inner shaft 22 due to the operation of the brake control device, torque is not transmitted from the inner shaft 22 to the housing 21. Is not hindered.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the overall structure of an embodiment of a driving force distribution device according to the present invention.

2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a partially enlarged sectional view of the two-way clutch of the embodiment shown in FIG.

FIG. 4 is a partially enlarged perspective view showing the ball guide of the embodiment shown in FIG. 1 and a ball held by the ball guide.

FIG. 5 is a diagram for explaining the operation of the two-way clutch shown in FIG.

FIG. 6 is a skeleton diagram showing an example in which the driving force distribution device shown in FIG. 1 is applied to a real-time four-wheel drive vehicle.

[Explanation of symbols]

21 ... Outer rotating member (housing), 22 ... Inner rotating member (inner shaft), 25 ... Friction clutch, 30 ... Pressing force generating means, 31 ... Pressing piston, 32 ... Rotor, 3
2b ... Blade part, 32c ... Inner peripheral surface, 33 ... Annular chamber, 3
5 ... two-way clutch, 36 ... concave cam surface, 37 ... ball, 38 ... ball guide, 38a ... holding hole

Continued front page    (72) Inventor Akinori Miman             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. (72) Inventor Hiroyuki Shimogasa             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Car Co., Ltd. F term (reference) 3D043 AA04 AA06 AB17 EA02 EA18                       EA38 EB02 EB06 EB12 EB13                       EC01 EE03 EE07 EF06 EF12                       EF19 EF24                 3J057 AA04 BB04 GA26 GA64 GC04                       HH02

Claims (5)

[Claims] 1. An outer rotary member, an inner rotary member coaxially rotatably supported by the outer rotary member, and an increase in relative rotational speed between the rotary members provided between the rotary members. The pressing force generating means for generating a pressing force according to the above, and the transmission torque between the rotating members increases in accordance with the increasing pressing force generated between the rotating members provided between the rotating members. A pressing piston, comprising a friction clutch, wherein the pressing force generating means is coaxially slidably fitted in the outer rotating member, and one side surface is arranged to press the friction clutch, and the pressing piston. A ring-shaped chamber formed between the other side surface of the piston and the outer rotating member, and a fluid pressure for rotating the viscous fluid that is connected to the inner rotating member and enclosed in the ring-shaped chamber to operate the pressing piston are generated. Has a blade part to In the driving force distribution device including the rotor, the rotor is connected to the inner rotating member via a two-way clutch. 2. The driving force distribution device according to claim 1, wherein the two-way clutch is formed on an inner peripheral surface of the rotor and has a plurality of concave cam surfaces having engaging slopes on both sides in the circumferential direction. A ball disposed between each concave cam surface and the outer peripheral surface of the inner rotating member, and a plurality of holding holes slidably fitted to the inner peripheral surface of the rotor to hold the balls are formed. A driving force distribution device comprising a ball guide. 3. The driving force distribution device according to claim 2, wherein the holding hole has a force that presses the ball against the outer peripheral surface of the inner rotating member when the ball moves in the circumferential direction with respect to the ball guide. A driving force distribution device having a shape for generating 4. The drive force distribution device according to claim 2 or 3, wherein the ball guide is arranged at a position displaced outward in a radial direction of the rotary members from a center of each ball. And a driving force distribution device. 5. The driving force distribution device according to claim 2, wherein the holding hole has an elongated shape in a circumferential direction of the ball guide. apparatus.