JP2521822Y2 - Driving force transmission device for four-wheel drive vehicles - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force transmitting device for a four-wheel drive vehicle which transmits driving force between an input shaft and an output shaft for a four-wheel drive vehicle.

[0002]

2. Description of the Related Art In recent years, four-wheel drive vehicles have been rapidly spreading in recent years because they are not only excellent on rough roads, but also excellent on acceleration and running stability on general roads. Conventionally, in this four-wheel drive vehicle, a drive shaft of a front wheel and a drive shaft of a rear wheel are rigidly connected. However, in this case, when the rotation speed of the front wheel and the rear wheel is different due to the difference in the turning radius of the front wheel and the rear wheel during the turning traveling, the propulsion shaft is twisted and the turning radius is changed. However, there is a drawback in that a so-called tight corner braking phenomenon occurs in which the small rear wheel is dragged in a state in which slippage occurs and rattling occurs in the vehicle. Therefore, in the current four-wheel drive vehicle, in order to prevent the above-described tight corner braking phenomenon and the like, a driving force transmission device capable of allowing a difference in rotation speed between the two drive shafts between the two drive shafts is provided. Intervening.

As the above-mentioned driving force transmitting device, there has been provided a hydraulic pump type device using a so-called viscous coupling, a vane pump or the like. The above viscous
In the coupling, a number of inner plates rotating with one of the drive shafts and an outer plate rotating with the other are alternately arranged in proximity to each other, and both plates have a very high viscosity therebetween. Sealed with oil interposed. In a normal state, the inner plate and the outer plate are coupled to each other by a fluid frictional force between the oil interposed therebetween and a shearing force inside the oil, and torque is transmitted. When the difference between the rotation speeds of the two becomes large, the oil is agitated to cause thermal expansion, so that the two plates are pressed against each other, so that the two drive shafts are directly connected, and the transmission torque is rapidly increased (so-called Hump phenomenon).

On the other hand, the above-mentioned hydraulic pump type devices include:
In some cases, a vane pump is formed by disposing a rotor with a vane that rotates together with one of the two drive shafts in a cam ring of a casing that rotates coaxially with the other rotor. In this vane pump, the rotor and the cam ring are connected via pressure oil interposed therebetween, and torque is transmitted between both drive shafts. In principle, this transmission torque increases as the pressure generated by the vane pump increases, that is, as the rotational speed difference between the two drive shafts increases.

[0005]

In the viscous coupling, the direct connection state can be realized as described above. Therefore, it can be used as a limited slip differential, for example, incorporated in a differential to directly connect the left and right wheels when required. The advantage is that it is possible. However, there are problems in durability, such as breakage of the seal due to an explosive increase in internal pressure when the hump phenomenon occurs, and deterioration of the oil between the plates due to shearing.

On the other hand, the hydraulic pump type device has an advantage that the oil is hardly deteriorated and the durability is excellent because the drive is transmitted not by the shearing force of the oil but by the internal pressure. However, when the generated pressure increases, a phenomenon occurs in which a side plate constituting a pressure chamber of the vane pump disposed on both end surfaces of the cam ring is deformed, and a gap between the rotor and the side plate becomes large.
An increase in the generated pressure is suppressed, and there is a problem that a sufficient increase in the transmission torque cannot be obtained with respect to an increase in the rotational speed difference between the two drive shafts. In order to solve this difficulty, it is conceivable to increase the thickness of the side plate to increase the rigidity, but it has been sometimes difficult in terms of space.

Therefore, in order to solve the problems of both types at once, a multi-plate clutch is incorporated adjacent to the hydraulic pump type device to increase the difference in rotational speed between both drive shafts (ie, the hydraulic pump). A driving force transmission device in which both drive shafts are directly connected to each other by pressing a multi-plate clutch by a cam mechanism at the time of an increase in transmission torque due to a driving mechanism (for example, Japanese Patent Application No. 2-61737). reference).

However, in this driving force transmission device, it is necessary to newly provide a cam mechanism, so that there is a new problem that the entire device becomes large and the manufacturing cost increases. On the other hand, instead of the cam mechanism, it is conceivable to press the multi-plate clutch with a piston that receives hydraulic pressure guided from a hydraulic pump, but in this case,
Since a new piston is provided, there is a problem in that the manufacturing cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a small-sized, low-cost, low-cost four-wheel-drive driving force transmission device which is excellent in durability and can rapidly increase transmission torque when required. I do.

[0010]

In order to achieve the above object, a driving force transmission device for a four-wheel drive vehicle according to the present invention includes: a housing that rotates in conjunction with one of a pair of drive shafts;
A rotating member interlockingly rotating with the other drive shaft and rotatable relative to the housing and axially movable relative to the housing; and a rotating speed interposed between the housing and the rotating member, and between the two. A hydraulic pump that transmits torque between the two by a hydraulic pressure generated according to the difference, and a multi-plate clutch interposed between both the housing and the rotating member, wherein the rotating member receives the discharge pressure of the hydraulic pump It is characterized by comprising a pressure receiving portion, and a pressing portion that presses the multi-plate clutch to press the multi-plate clutch in a state where the pressure receiving portion receives the discharge pressure.

[0011]

According to the driving force transmitting apparatus for a four-wheel drive vehicle having the above-described structure, when the rotational speed difference between the housing and the rotary member is small, the hydraulic pump transmits torque between the two. . When the rotation speed difference becomes large, the rotating member receives the discharge pressure of the hydraulic pump at the pressure receiving portion, moves in the axial direction, and presses the multi-plate clutch by the pressing portion to press the multi-plate clutch into pressure. . Thus, the multi-plate clutch can be directly connected to transmit the torque via the multi-plate clutch, and the transmission torque can be rapidly increased. This increase in torque is caused by a normal increase in internal pressure in the hydraulic pump, not by an explosive increase in internal pressure such as in a viscous coupling.

Further, since the multi-plate clutch is pressed by the rotating shaft receiving the discharge pressure of the hydraulic pump, the pressing shaft of the multi-plate clutch is also used by the rotating shaft. Further, no cam mechanism is required.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a cross-sectional view showing a driving force transmission device for a four-wheel drive vehicle as one embodiment of the present invention. In FIG. 1, the driving force transmission device is a front-wheel drive shaft such as a propeller shaft. A housing 1 that rotates in conjunction with the
A rotary cylinder shaft 2 that is rotatable relative to the housing 1 and is movable in the axial direction and that rotates in conjunction with a rear wheel drive shaft R such as a differential shaft; And a vane pump 3 as a hydraulic pump and a multi-plate clutch 4 interposed therebetween. In the following, left and right in the figures are referred to as left and right.

The housing 1 includes a first housing 11, a second housing 12, and a third housing 13. The first housing 11 and the second housing 12 are connected to the bolt 1a.
Are connected so as to be integrally rotatable. The first housing 11 and the third housing 13 are integrally rotatably connected by bolts 1b. Driving force is transmitted to the housing 1 from the front wheel-side drive shaft via the gear portion 11a of the first housing 11. At the left end of the shaft insertion hole 13c of the third housing 13, inner peripheral steps 13e and 13f are formed.

At the left end of the rotary cylinder shaft 2, a flange-shaped pressing portion 21 is formed.
a is in contact with an operation member 43 of the multi-plate clutch 4 which will be described later. The inner peripheral surface of the rotary cylinder shaft 2 has an inner peripheral reduced diameter portion 2b.
And an inner peripheral enlarged diameter portion 2c into which the rear wheel drive shaft R is inserted. A female spline portion 2d spline-coupled to the rear wheel drive shaft R is formed in the inner peripheral enlarged diameter portion 2c. The outer peripheral surface of the rotary cylinder shaft 2 has an outer peripheral right portion 2e, an outer peripheral intermediate portion 2f, and an outer peripheral left portion 2g whose diameters are sequentially increased. The outer right side portion 2e is slidably and rotatably fitted in the inner peripheral step portion 13e of the third housing 13. The outer right side portion 2e is in close contact with the high pressure seal 61 mounted on the inner peripheral step 13f of the third housing 13.
The seal 61 seals the space between the rotary cylinder shaft 2 and the third housing 13.

A male spline portion 2h, which is spline-coupled to a rotor 31 described later, of the vane pump 3 is formed on the outer right side portion 2e of the rotary cylinder shaft 2. A space surrounded by the first housing 11, the second housing 12, the third housing 13, the rear wheel drive shaft R and the rotary cylinder shaft 2 forms a housing portion 8 housing the vane pump 3 and the multi-plate clutch 4. I have.

Referring to FIG. 1 and FIGS. 2 and 3 showing the principle of internal pressure generation, the vane pump 3
A cam ring 32 including the rotor 31 and being sandwiched by the third housing 13 also serving as the right side plate and the left side plate 10 to form a plurality of pump chambers with the rotor 31; 3
A main part is constituted by a plurality of vanes 34 protruding from the accommodation groove on the outer periphery of the cam ring 32 and pressed against the inner surface of the cam ring 32 by the coil spring 33 to partition the pump chamber into the working chambers A and B.

An inner peripheral portion of the side plate 10 is slidably and rotatably fitted to an outer peripheral intermediate portion 2f of the rotary cylinder shaft 2 and is slidably rotatable on an outer peripheral left portion 2g of the rotary cylinder shaft 2. And an enlarged diameter portion to be fitted. A seal 62 seals between the enlarged diameter portion of the side plate 10 and the outer left side portion 2 g of the rotary cylinder shaft 2. As shown in FIG. 2, the vane 34 is provided with an orifice 34a that allows oil to flow between the working chamber A and the working chamber B partitioned by the vane 34. Further, ring-shaped steps 31a and 31b are provided on both side surfaces of the rotor 31 so that the lower portions of the accommodation grooves of the respective vanes 34 communicate with each other.
Referring to FIG. 1 and FIG. 2, these step portions 31a, 31
b are operating chambers A and B via oil passages 38a and 38b built in the side plate 10 and the third housing 13.
Has been communicated with. That is, the pressure oil from the high-pressure side of the working chambers A and B acts to press the vane 34 toward the inner peripheral wall of the cam ring 32,
The adhesion of the vane 34 to the inner peripheral wall of the cam ring 32 is enhanced. Since the check valves 39a and 39b permitting only the flow of oil to the lower part of the vane are provided in the oil passages 38a and 38b, respectively, the working chamber on the low pressure side of the working chambers A and B is provided. And steps 31a and 31b
The check valve provided in the oil passage connecting
It prevents the pressure in the working chamber on the low pressure side from increasing.

A step 31a on the side plate 10 side is provided.
Are oil guide holes 50 penetrating the side plate 10 in the axial direction.
Through the oil chamber 51. This oil chamber 51
Is provided between the rotary cylinder shaft 2 and the side plate 10, and applies the oil pressure of the step portion 31 a, that is, the oil pressure from the high-pressure side working chambers A and B of the vane pump 3 to the pressure receiving portion 22. The operation of the vane pump 3 will be described. For example, when the rear wheel drive shaft R rotates faster than the front wheel drive shaft in a state where the front wheels are about to be locked at the time of braking, the rotor 31 rotates relatively quickly with respect to the cam ring 32. That is, the rotor 31 relatively rotates clockwise as shown in FIG. 9, and the vane 34 moves toward the working chamber A. At this time, the orifice 3 provided in the vane 34
Since 4a has a small diameter, the oil moves from the working chamber A to the working chamber B with outflow resistance. As a result, a high pressure is generated in the working chamber A, and the high pressure is generated by the vane 34 and the cam ring 3.
2 acts as a piston pressure on the working chamber A surrounded by the reference numeral 2 and serves as a torque transmitting medium, whereby torque is transmitted from the rotor 31 to the cam ring 32. Therefore, the brake torque from the rear wheel that is not locked is also transmitted to the front wheel that is likely to be locked, and the braking force against the road surface is secured.

The above pressure increases as the rotational speed difference between the rotor 31 and the cam ring 32 increases, and the pressure difference between the front wheel drive shaft and the rear wheel drive shaft R increases. Is transmitted. On the other hand, FIG. 10 shows a state where the cam ring 32 rotates clockwise relative to the rotor 31 when the front wheel slips and the front wheel side drive shaft rotates faster than the rear wheel side drive shaft R. ing.
In this case, since the vane 34 moves in the direction of the working chamber B, a high pressure is generated in the working chamber B, and torque is transmitted from the front wheel drive shaft to the rear wheel drive shaft R via the high pressure. Is done. In other words, from the slippery front wheel drive shaft,
Torque is transmitted to the rear-wheel drive shaft R on the non-slip side, and torque is automatically distributed to ensure a gripping force on the road surface.

The multi-plate clutch 4 includes a plurality of outer plates 4 spline-connected to the inner peripheral surface of the first housing 11.
1, an operating member 43 spline-coupled to the rear wheel drive shaft R and movable in the axial direction; an inner plate 42 spline-coupled to the operating member 43 and alternately combined with the outer plate 41; Interposed between the second housing 12 and the operating member 43, the two plates 41,
A disc spring 44 for urging in a direction in which the disc spring 42 moves away, and a sliding plate 4 interposed between the disc spring 44 and the operating member 43.
5 and a thrust bearing 46. A female spline portion 43a that is spline-connected to the rear wheel drive shaft R is formed on an inner peripheral portion of the operating member 43.

According to this embodiment, when the rotational speed difference between both the front wheel side drive shaft and the rear wheel side drive shaft R, that is, between the housing 1 and the rotary cylinder shaft 2 is small, the vane pump 3 is used. , And torque transmission between the two is performed. When the rotation speed difference becomes larger than a predetermined value, the side plate 1 of the vane pump 3 is removed from the pump chamber.
The pressing portion 21 of the rotary cylinder shaft 2 is pressed toward the operating member 43 side (left side) of the multi-plate clutch 4 by the discharge pressure of the oil discharged into the oil chamber 51 through the oil guide hole 50 of zero. Thus, the operating member 43 presses the outer plate 41 and the inner plate 42 into contact with each other, so that the front drive shaft R and the rear drive shaft R can be directly connected. As a result, FIG.
As shown by the solid line in FIG. 5, the transmission torque rises in proportion to the increase in the rotational speed difference, so that the transmission torque can be rapidly increased. Therefore, for example, it is possible to incorporate it into a differential and use it as a limited slip differential.

In addition, the rapid increase in the torque is caused by a normal internal pressure increase in the vane pump 3 and not by an explosive internal pressure increase such as a viscous coupling. It is possible to solve the problem of deterioration of durability due to the excessive increase in internal pressure. As described above, the disadvantages of the viscous coupling and the hydraulic pump type device can be solved at once.

The rotary cylinder shaft 2 itself moves in the axial direction by the discharge pressure and presses the operating member 43 of the multi-plate clutch 4. That is, the rotary cylinder shaft 2
Since the piston for pressing the operating member 43 is also used, the size of the device can be significantly reduced as compared with a case where a separate piston is provided. Further, the above-described multi-plate clutch 4
Since no cam mechanism is required for pressing the device, the size of the apparatus can be further reduced. In addition, since the number of parts can be reduced by eliminating the need for the piston and the cam mechanism, the manufacturing cost can be reduced.

In particular, since the transmission of the high torque is performed in a state in which the vane pump 3 is completely bypassed, that is, in a state in which no load is applied to the vane pump 3, the constituent members of the vane pump 3 can be thinned. In addition, the size and weight of the device can be further reduced. In addition, since the vane pump 3 does not move, the right side plate of the vane pump 3 is connected to the third housing 1 as in the present embodiment.
3, thereby further reducing the size and lowering the manufacturing cost.

Further, since the thrust bearing 46 is interposed between both the operating member 43 of the multi-plate clutch 4 and the second housing 12, the sliding friction between the two due to the relative rotation of the two by the thrust bearing 46. The generation of force can be suppressed, and the transmission torque between the two drive shafts due to the addition of friction torque can be significantly reduced, especially in a low speed rotation range.

Further, by changing the area of the pressure receiving portion 22 of the rotary cylinder shaft 2, the pressing force applied to the multi-plate clutch 4 can be varied. It can be adjusted as shown. The above-described rising characteristics can also be adjusted by adjusting the urging force of the disc spring 44. Further, since both plates 41 and 42 of the multi-plate clutch 4 are arranged at positions outside the vane pump 3, the axial dimension of the entire apparatus can be shortened.

The present invention is not limited to the above embodiment. For example, this driving force transmission device is used for transmitting torque between a left front wheel drive shaft and a right front wheel drive shaft. Various design changes can be made without departing from the gist of the present invention, such as for use in transmitting torque between the left rear wheel drive shaft and the right rear wheel drive shaft.

[0029]

As described above, according to the driving force transmitting apparatus for a four-wheel drive vehicle of the present invention, when the rotational speed difference between the housing and the rotating member is small, the transmission of torque between the two by the hydraulic pump is performed. However, when the rotation speed difference becomes large, the multiple disc clutch is pressed via the rotating member by the discharge pressure from the hydraulic pump, and the multiple disc clutch is directly connected to transmit torque through the multiple disc clutch. As a result, the transmission torque can be rapidly increased. In addition, this increase in torque is performed by a normal increase in the internal pressure of the hydraulic pump, and is not performed by an explosive increase in the internal pressure as in a viscous coupling.

Further, since the rotating member also serves as a piston for pressing the multi-plate clutch, the device can be significantly reduced in size as compared with a case where a separate piston is provided, and furthermore, it is possible to press the multi-plate clutch. This eliminates the need for the cam mechanism, thereby further reducing the size of the apparatus and the number of parts, thereby achieving a unique effect that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a driving force transmission device for a four-wheel drive vehicle according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing the operation of a vane pump.

FIG. 3 is a schematic sectional view showing the operation of a vane pump.

FIG. 4 is a diagram showing a relationship between a rotational speed difference and a transmission torque.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Rotating cylinder shaft 21 Pressing part 22 Pressure receiving part 3 Vane pump (hydraulic pump) 4 Multi-plate clutch

Claims (1)

(57) [Scope of request for utility model registration] 1. A housing that rotates in conjunction with one of a pair of drive shafts, and a rotation that rotates in conjunction with the other drive shaft and is rotatable relative to the housing and axially movable relative to the housing. A hydraulic pump that intervenes between the member and the housing and the rotating member, and that transmits torque between the member and the housing by using a hydraulic pressure generated according to a rotational speed difference between the housing and the rotating member; The rotating member includes a pressure receiving portion that receives the discharge pressure of the hydraulic pump, and a pressing portion that is pressed against the multiple disk clutch while the pressure receiving portion receives the discharge pressure. Driving force transmission device for four-wheel drive vehicles.