JPH03262730A - Driving force transfer device for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To improve durability and transfer performance by transferring the torque with a differential pump when the rotating speed difference between the right and left wheel drive shafts is small, moving the differential pump with a cam mechanism to directly connect a multi-plate clutch for the torque transfer when the rotating speed difference is large. CONSTITUTION:A vane pump 3 as a differential pump, a multi-plate clutch 4, and a cam mechanism 5 for directly connecting the multi-plate clutch 4 are arranged between a housing 1 integrally rotated with a left front wheel drive shaft L and a hollow rotary shaft 2 integrally rotated with a right front wheel drive shaft R and relatively rotated with respect to the housing 1 to constitute a driving force transfer device. When the rotating speed difference between th right and left front wheel drive shafts R, L is relatively small, the torque is transferred between them by the vane pump 3. When the rotating speed difference is relatively large, the vane pump 3 is moved to the multi-plate clutch 4 side by the cam mechanism 5, and both the outer and inner plates 41, 42 are pressed to each other.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a driving force transmission system for a four-wheel drive vehicle that is interposed between an input shaft and an output shaft of the four-wheel drive vehicle to transmit driving force. Regarding equipment.

<Prior Art> Four-wheel drive vehicles have become rapidly popular in recent years because they not only have excellent ability to travel on rough roads, but also have excellent acceleration and driving stability on ordinary roads.

Conventionally, there has been a four-wheel drive vehicle in which a front wheel drive shaft and a rear wheel drive shaft are rigidly connected. but,
In this case, if there is a difference in the rotation speed of the front wheels and the rear wheels due to the difference in the turning radius between the front wheels and the rear wheels during turning, the propulsion shaft will be twisted, and the turning radius will be small. There was a problem in that a so-called tight corner braking phenomenon occurred, in which the rear wheels were dragged while slipping, causing the vehicle to wobble. Therefore, in current four-wheel drive vehicles, in order to prevent the above-mentioned tight corner braking phenomenon, a driving force transmission device that can tolerate the difference in rotational speed between the re-driving axles is installed between the re-driving axles. Intervening.

As the above-mentioned driving force transmission device, a so-called VCU (viscous coupling unit) and a differential pump type device using a vane pump or the like are provided.

The above-mentioned VCU has a large number of inch plates that rotate together with one of the drive shafts and an outer plate that rotates together with the other drive shaft, which are alternately arranged in close proximity. It is sealed with oil in between. In a normal state, the inner plate and the outer plate are coupled to each other by fluid frictional force between the oil interposed therebetween, and torque is transmitted.

When the difference in rotational speed between the two becomes large, the oil is agitated and thermally expands, causing both plates to be pressed together and the two moving shafts to be directly connected, causing a sudden increase in the transmitted torque (hump). phenomenon).

On the other hand, in the differential pump type device, a rotor with vanes that rotates together with one of the driving shafts is disposed coaxially with the rotor and within a cam ring of a casing that rotates with the other. It constitutes a vane pump. Then, the rotor and the cam ring are coupled via pressure oil interposed between them, and torque is transmitted between the redrive shafts.

In principle, this transmission torque increases as the pressure generated by the vane pump increases, that is, as the difference in rotational speed between the re-driving shafts increases.

<Problems to be Solved by the Invention> Since the VCU can achieve a direct connection state as described above, it can be incorporated into a differential, for example, and used as a limited slip differential that directly connects the left and right wheels when necessary. There is an advantage. However, there were problems with durability, such as the seals being damaged due to the explosive increase in internal pressure when the hang phenomenon occurred, and the oil between the plates deteriorating due to shearing.

On the other hand, in a differential pump type device, drive is transmitted by internal pressure rather than oil shearing force, so the advantage is that the oil is less likely to deteriorate and has excellent durability. However, when the generated pressure increases, the cam ring expands, creating a gap between the cam ring and the vane, and the side plates that make up the pressure chambers of the vane pump, which are placed on both end faces of the cam ring, deform, causing the rotor and side plates to deform. A phenomenon occurs in which the gap between There was a problem. In order to solve this problem, it may be possible to increase the rigidity by increasing the thickness of the side plate, but this may be difficult due to space considerations.

The purpose of this invention is to solve the problems of both of the above methods at once, and to provide a driving force transmission device for four-wheel drive vehicles that is highly durable and capable of rapidly increasing the transmitted torque when required. do.

Means for Solving the Problems> In order to achieve the above object, a driving force transmission device for a four-wheel drive vehicle according to the present invention provides a driving force transmission device for a four-wheel drive vehicle that is interposed between a pair of drive shafts to transmit torque. In the driving force transmission device for the above-mentioned pair of drive shafts, a housing is provided so as to be integrally rotatable with one of the drive shafts, and a housing is provided so as to be integrally rotatable with the other drive shaft, and is rotatable relative to the housing. The rotating shaft is interposed between the housing and the rotating shaft, and is arranged to be movable in the axial direction of the rotating shaft, and is interlocked with the housing via a cam mechanism formed between the housing and the housing. A differential pump that transmits torque between the two using hydraulic pressure generated according to the difference in rotation speed between the two,
The multi-disc clutch is interposed between the above two and disposed adjacent to the differential pump, and is frictionally engaged when pressed by the differential pump to transmit torque between the two. It is.

According to the drive force transmission device for a four-wheel drive vehicle configured as described above, when the rotational speed difference between the housing and the rotating shaft is less than a predetermined value, the differential pump does not transmit torque between the two. There is. When the rotational speed difference becomes larger than a predetermined value, the cam mechanism moves the differential pump to directly connect the multi-disc clutch, transmitting torque via the multi-disc clutch, and suddenly increasing the transmitted torque. can be increased to This increase in torque is done mechanically by a cam mechanism and is not done by an explosive increase in internal pressure as in a VCU.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 1 is a sectional view showing a driving force transmission device for a four-wheel drive vehicle as an embodiment of the present invention, and in the same figure, this driving force transmission device rotates integrally with the left front wheel drive shaft. A housing 1, a hollow rotating shaft 2 that is rotatable relative to the housing 1 and rotates integrally with the right front wheel drive shaft R, and a differential pump interposed between the housing 1 and the rotating shaft 2, respectively. It has a vane pump 3 and a multi-disc clutch 4, and a cam mechanism 5 that directly connects the multi-disc clutch 4 when necessary.

The housing 1 consists of a first housing 11 and a second housing 12 that are connected by a bolt 1a through a seal member (not shown), and the housing 1 receives driving force from a transmission through a gear part 11a. communicated. The rotary shaft 2 is slidably and rotatably inserted through the shaft insertion hole 11c of the first housing 11, and the tip 2a of the rotary shaft 2 is slidably and rotatably inserted into the boss portion 12a of the second housing 12. It is fitted inside. The first housing 11, the second housing 12, and the rotating shaft 2 form a housing portion 8 that houses the differential pump 3 and the multi-disc clutch 4.

This housing portion 8 is sealed by a seal 6 interposed between the rotating shaft 2 and the first housing 11 and a seal 7 interposed between the rotating shaft 2 and the second housing 12. Inside the housing part 8, the multi-disc clutch 4 is lubricated,
It is also filled with oil that serves as a medium for torque transmission by the vane pump 3.

Figure 1, and Figures 2 and 3 showing the principle of internal pressure generation.
Referring to the figure, the vane pump 3 includes a rotor 31, a cam ring 32 that encloses the rotor 31 and forms a plurality of pairs of working chambers A and B that generate oil pressure between the rotor 31 and the rotor 31, and a groove on the outer periphery of the rotor 31. A plurality of vanes 34 protrude from the cam ring 32 and are pressed against the inner surface of the cam ring 32 by a coil spring 33.
, a plurality of pairs of check valves 35 and 36 such as ball valves provided corresponding to the working chambers A and B, an operating member 9 as a side plate, and a cam forming body 10. The pump chamber of the vane pump 3 includes a differential member 9, a cam forming body 10, a cam ring 32, and a rotor 31. This pump chamber is partitioned into the working chamber A and the working chamber B by vanes 34.

The check valve 35 is connected to the discharge hole 3 provided in the main body of the rotor 31.
It is placed in the middle of 1a, and only restricts the outflow of pressure oil from the pump chamber. The discharge hole 31a opens between the mounting positions of the adjacent vanes 34 on the outer peripheral surface of the main body of the rotor 31, and has a predetermined depth in the radial direction,
Its bottom portion communicates with annular grooves 31c formed on both sides of the rotor 31 body through separate oil guide holes 31b in the axial direction of the rotor 31 body. The check valve 36 is built into the cam forming body 10 and only allows oil to flow into the pump chamber from the housing portion 8. In addition, in FIGS. 2 and 3, the check valves 35, 36 are schematically disposed within the cam ring 32 for illustrative purposes. Further, the coil spring 33 is not shown.

The rotor 31 is spline-coupled to the right front wheel drive shaft R via the rotating shaft 2 so as to be integrally rotatable therewith, and is movable in the axial direction of the rotating shaft 2 . The cam ring 32 has bolts 37 attached to the actuating member 9 pressed by the multi-disc clutch 4 and the cam forming body 10 that rotates integrally with the first housing 11.
connected by. The cam ring 32 rotates integrally with the left front wheel drive shaft via the cam forming body 10 and the housing 1. The vane 34 includes, as shown in FIG.
Working chamber A and working chamber B partitioned by the vane 34
An orifice 34B is provided to allow oil to flow between. The operating member 9 and the rotating shaft 2 and the cam forming body 10 and the rotating shaft 2 are configured to be relatively movable while maintaining a substantially liquid-tight state.

The function of the vane pump 3 will be explained. For example, if the right front wheel slips and the right front wheel drive shaft R rotates faster than the left front wheel drive shaft, the rotor 31 rotates clockwise relative to the cam ring 32 as shown in FIG. Then, the vane 34 moves toward the working chamber A. At this time, since the orifice 34a provided in the vane 34 has a small diameter, the oil cannot move smoothly from the working chamber A to the working chamber B. Therefore, the oil in the working chamber A tends to flow into the storage section 8 where the oil is stored, but this is prevented by the check valve 36.

As a result, high pressure is generated in the working chamber A, and the vane 34 pushes the cam ring 32 through this high pressure, causing the rotor 31
Torque is transmitted from the cam ring 32 to the cam ring 32. That is,
Torque is transmitted from the right front wheel drive shaft R on the slipping side to the left front wheel drive shaft R on the non-slip side, and torque is automatically distributed to ensure grip on the road surface.

The above pressure increases as the rotational speed difference between the rotor 31 and the cam ring 32 increases. Torque is transmitted. Further, oil is supplied to the working chamber B from the housing portion 8 via the open check valve 35.

FIG. 3 shows a state in which the cam ring 32 rotates clockwise relative to the rotor 31 when the left front wheel slips and the left front wheel drive shaft rotates faster than the right front wheel drive shaft R. It shows. In this case, as the vane 34 moves toward the working chamber B, high pressure is generated in the working chamber B, and through this high pressure, torque is transmitted from the left front wheel drive shaft to the right front wheel drive shaft R. Ru. In addition, check valve 3
5 is closed, and the check valve 36 is opened, and oil is supplied from the housing portion 8 to the working chamber A through the check valve 36.

The actuating member 9 directly connects the multi-disc clutch 4 by being pressed by the multi-disc clutch 4, and is biased in a direction away from the multi-disc clutch 4 by a disc spring 13 serving as a biasing means. has been done.

Referring to FIGS. 1 and 4, the cam forming body 10 has a cam portion 10a formed in a wave shape along the circumference, and this cam portion 10a has a similar shape to the cam portion. The cam portion 11b of the first housing 11 is engaged with the cam portion 11b of the first housing 11, which is formed in a wave shape. A cam mechanism 5 is constituted by the cam portion 10a and the cam portion 11b. This cam mechanism is actuated by an axial biasing force from the disc spring 13 via the vane pump 3. Therefore, when the rotational speed difference between the cam ring 32 and the housing 1 is small, the biasing force acts on the cam portion 10a and The cam portions 11b are assembled as shown in FIG. Then, when the rotational speed difference becomes greater than a predetermined value, the cam portion 10a and the cam portion 11b cause a relative shift in the rotational direction, as shown in FIG. 5, thereby reducing the axial distance between them. Keep away, disc spring 13
The actuating member 9 is pressed against the multi-disc clutch 4 against this force.

The multi-plate clutch 4 includes a plurality of outer plates 41 spline-coupled to the first housing 11 and inner plates 42 spline-coupled to the rotating shaft 2 and alternately combined with the outer plates 41. Note that even when the multi-disc clutch 4 is not pressed by the actuating member 9, some torque is transmitted due to the torque flow via the vane pump 3.

According to this embodiment, when the difference in rotation speed between both the left front wheel drive shaft and the right front wheel drive shaft R, that is, between the housing 1 and the rotating shaft 2 is small, the vane pump 3
Torque is transmitted between the two. When the rotational speed difference becomes larger than a predetermined value, the cam mechanism 5
However, the vane pump 3 is moved to the multi-disc clutch 4 side, and the outer plate 41 of the multi-disc clutch 4 is moved by the actuating member 9.
By pressing the inch plate 42, the left front wheel drive shaft and the right front wheel drive shaft R can be directly connected. Thereby, as shown in FIG. 6, the transmission torque can be increased in proportion to the increase in the rotational speed difference, and the transmission torque can be rapidly increased. Therefore, it can also be used as a limited slip differential.

Moreover, the sudden increase in torque is done mechanically by the cam mechanism 5, and is not done by an explosive increase in internal pressure like in a VCU. The problem of deterioration of durability can be solved. In this way, the drawbacks of VCU and differential pump type devices can be solved all at once.

Furthermore, a vane pump 3 is provided in the housing portion 8 of the housing 1.
and the multi-disc clutch 4 are collectively accommodated, and oil sealed in the accommodation section 8 is provided for lubrication between each plate of the multi-disc clutch 4 and is also circulated and supplied into the vane pump 3. Therefore, there is no need to provide a separate oil tank, and the structure can be simplified.

By adjusting the biasing force of the spring 13 and the cam shape of the cam mechanism 5, the level of the rotational speed difference that increases the transmission torque can be adjusted, for example, as shown by the broken line in FIG. 6.

7 and 8 show other embodiments.

Referring to these figures, in this embodiment, the housing 1
The pump chamber of the vane pump 3 is isolated in the housing part 8 of the vane pump 3, and in this case, the working oil of the vane pump 3 and the lubricating oil of the multi-disc clutch 4 in the housing part 8 are made different, depending on the characteristics of each. You can use different ones.

Further, the actuating member 9 configured separately from the side plate 91 of the basing 3 is spline-coupled to the rotating shaft 2 and extends to the outside of the vane pump 3 in the radial direction, and the actuating member 9 and the housing 1 are connected together. A multi-disc clutch 4 is formed between the two, thereby making it possible to shorten the axial dimension of the entire device.

Furthermore, in this embodiment, the cam mechanism 5 includes the cam portion 10a.
, 11. It consists of a ball cam mechanism in which balls 10c are spaced apart in the axial direction and a ball 10c held by a cage 10d is interposed between these opposing surfaces.

The present invention is not limited to the above-mentioned embodiments, but also includes using this driving force transmission device for torque transmission between a propulsion shaft and a rear wheel drive shaft, and a left rear wheel drive shaft and a right rear wheel drive shaft. Various design changes can be made without changing the gist of the invention, such as using it for torque transmission between.

<Effects of the Invention> As described above, according to the present invention, when the rotational speed difference between the housing and the rotating shaft is less than a predetermined value, torque is transmitted between the housing and the rotating shaft by the differential pump. When the rotational speed difference becomes larger than a predetermined value, the cam mechanism moves the differential pump to directly connect the multi-disc clutch, transmitting torque via the multi-disc clutch, and rapidly increasing the transmitted torque. be able to. Moreover, this torque increase is mechanically performed by a cam mechanism, and the VCU
Since this is not done by an explosive increase in internal pressure as in

[Brief explanation of drawings]

Fig. 1 is a sectional view of a driving force transmission device for a four-wheel drive vehicle as an embodiment of the present invention, Figs. 2 and 3 are schematic sectional views showing the function of a vane pump, and Figs. 4 and 5. 6 is a schematic diagram of the cam mechanism, FIG. 6 is a diagram showing the relationship between the rotational speed difference and the transmitted torque, FIG. 7 is a sectional view of another embodiment of the driving force transmission device for a four-wheel drive vehicle, and FIG. 8 is the same. FIG. 3 is a schematic diagram of a cam mechanism. L... Left front wheel drive shaft (one drive shaft), R... Right front wheel drive shaft (other drive shaft), 1... Housing,
2... Rotating shaft, 3... Vane pump (differential pump)
, 4...Multi-plate Kura Sochi, 5...Cam mechanism. (1 other person) Fig. Fig. Fig. Fig. 1 Rotational speed difference 1- Housing 3... Vane pump (differential pump) 3 days

Claims (1)

[Claims] 1. In a four-wheel drive vehicle driving force transmission device that is interposed between a pair of drive shafts and transmits torque, the drive shaft can rotate integrally with one of the pair of drive shafts. a housing provided on the other drive shaft; a rotating shaft that is rotatably provided on the other drive shaft and can rotate freely relative to the housing; and a rotating shaft that is interposed between both the housing and the rotating shaft and moves in the axial direction of the rotating shaft. a differential pump that is freely disposed and interlocked with the housing via a cam mechanism formed between the two, and transmits torque between the two using hydraulic pressure generated according to the difference in rotational speed between the two; 4. A multi-disc clutch interposed between the two and disposed adjacent to the differential pump, frictionally engaged when pressed by the differential pump, and transmitting torque between the two. Drive force transmission device for wheel drive vehicles.