JPH0478326A - Driving force transfer device for four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To smoothen quick turn of a vehicle at the time of travelling at a low speed by bringing a differential pump into a pressure contact with a multiplate clutch with increase of the transfer torque of the differential pump, and interposing a thrust bearing between both the described ones, and reducing the friction to be caused by the relative rotation of the both. CONSTITUTION:When a difference of the number of rotation of a left side and a right side front wheel driving shafts becomes large, a cam mechanism 5 moves a vane pump to a multiplate clutch 4, and the described tow driving shafts are connected directly. The transfer torque is thereby increased quickly to eliminate the deterioration of durability. Since a thrust bearing 20 is interposed between the multiplate clutch 4 and a vane pump 3, generation of a the sliding friction to be caused by the relative rotation of the multiplate clutch 4 and the vane pump 3 can be restricted. The transfer torque between both the descibed driving shafts to be caused by the addition of the friction torque can be therefore reduced remarkably, especially in a low speed area. Consequently, quick turn of a vehicle at the time of travelling at low speed can be performed smoothly.

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.

<Conventional Technology> 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 have been four-wheel drive vehicles in which a front wheel drive shaft and a rear wheel drive shaft are rigidly connected. but,
With this, if there is a difference in the rotational speed of the front wheels and the rotational speed of the rear wheels due to the difference in the turning radius between the front and rear wheels during turning, the propulsion shaft will be twisted and the turning radius will be reduced. The problem was that the small rear wheels of the vehicle were dragged in a slipping state, causing the vehicle to wobble, a phenomenon known as tight corner braking. 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 viscous coupling, a differential pump type device using a vane pump, etc. are provided.

The above-mentioned viscous coupling has a number of inner 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 a highly viscous oil interposed. In a normal state, the inner plate and the outer plate are connected to each other by the fluid friction force between the two and 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 re-drive shaft 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 vane-equipped rotor that rotates with either one of the redrive shafts is disposed coaxially with the rotor and within a cam ring of a casing that rotates with the other. It consists of 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 rotation speed difference between the re-driving shafts increases.

<Problems to be Solved by the Invention> Since the viscous coupling can achieve a direct connection as described above, it can be used as a limited slip differential, for example, by incorporating it into a differential and directly connecting the left and right wheels when necessary. The advantage is that it is possible. However, there were problems with durability, such as seals being damaged due to an explosive increase in internal pressure when a hang phenomenon occurred, and 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.

Therefore, in order to solve the problems of both the above-mentioned systems at once, a multi-disc clutch is installed adjacent to the above-mentioned differential pump type device. A driving force transmission device has been proposed in which the re-drive shaft is directly connected by pressing a multi-disc clutch using a cam mechanism to bring it into pressure contact (when the transmitted torque increases) (see, for example, Japanese Patent Application No. 2-61737). ).

By the way, in order to prevent the above-mentioned tight corner braking phenomenon and smoothly perform sharp turns at low speeds,
In a low rotation range, it is desirable that the transmission torque between the re-driving shafts be small while allowing for a difference in the rotational speed between the re-driving shafts.

However, in the above-mentioned driving force transmission device, both the differential pump and the multi-disc clutch were in direct contact, so
Due to the relative rotation between the two, a thick edge friction force is generated between the contact surfaces of the two, and until the re-drive shaft is directly connected, the friction torque through this friction force or the re-drive is always generated. It is transmitted between the shafts.

In particular, since the transmission torque between the re-drive shafts in the low-speed rotation range is originally small, the addition of the friction torque described above increases it significantly, making it impossible to smoothly perform sharp turns when driving at low speeds. Ta.

This invention is a driving force for four-wheel drive vehicles that has excellent durability, can rapidly increase the transmitted torque when required, and has a small transmitted torque in the low-speed rotation range that allows the vehicle to smoothly make sharp turns at low speeds. The purpose is to provide a transmission device.

<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 includes a housing that rotates in conjunction with one drive shaft of a pair of drive shafts, and a housing that rotates in conjunction with one drive shaft of a pair of drive shafts; a rotating shaft that rotates in conjunction with the drive shaft of the housing and is rotatable relative to the housing; A differential pump that transmits torque between the two using oil pressure generated according to the difference in rotation speed; A multi-disc clutch that frictionally engages and transmits torque between the two, and the differential pump and housing are coupled together so that they can rotate together, and as the torque transmitted by the differential pump increases, the differential pump is connected to the multi-disc clutch. A thrust bearing is provided between the multi-disc clutch and the differential pump to reduce friction caused by relative rotation between the multi-disc clutch and the differential pump. It is something to do.

Preferably, the cam mechanism includes a pair of cam members removably attached to the housing and the vane pump, respectively.

According to the drive force transmission device for a four-wheel drive vehicle configured as described above, if the difference in rotational speed between the housing and the rotating shaft is less than a predetermined value, torque transmission between the two is performed by the differential pump. ing. When the rotational speed difference becomes larger than a predetermined value, the cam mechanism or the differential pump is moved to directly connect the multi-disc clutch, thereby transmitting torque via the multi-disc clutch and rapidly increasing the transmitted torque. It can be increased to This increase in torque is achieved mechanically by a cam mechanism and not by an explosive increase in internal pressure as in a viscous coupling.

In addition, since a thrust bearing is interposed between both the multi-disc clutch and the differential pump, the thrust bearing can suppress the generation of sliding friction force between the two due to their relative rotation, and the friction torque The transmission torque between the re-driving shafts due to the addition of this can be significantly reduced, especially in the low-speed rotation range.

Furthermore, if the cam mechanism has a pair of removable cam members, these cam members can be removed from the housing and vane pump and replaced with one of another specification with a different cam shape to improve the differential. The pressing force of the pump on the multi-disc clutch can be varied, thereby making it possible to adjust the rise characteristics of the transmitted torque.

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

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

The housing l consists of a first housing 11 and a second housing 12 that are connected by a bolt Ia through a sealing member (not shown), and the housing 1 receives driving force from a transmission through a gear part 11a. communicated. In the shaft insertion hole 11c of the 171st housing 11,
A rotary shaft 2 is slidably and rotatably passed through the rotary shaft 2, and a tip end 2a of the rotary shaft 2 extends through the boss portion 12a of the second housing 12.
It is fitted inside so that it can slide and rotate freely. The first housing 11, the second/S housing 12, and the rotating shaft 2 form a housing portion 8 that houses the vane pump 3 and the multi-disc clutch 4.

This housing part 8 includes a seal 61 interposed between the rotating shaft 2 and the first housing 11, a seal 62 interposed between the rotating shaft 2 and the second housing 12, and a seal 62 interposed between the rotating shaft 2 and the first housing 11. It is sealed by a seal 63 interposed between the second housing 12 and the second housing 12. The housing portion 8 is filled with oil that lubricates the multi-disc clutch 4 and serves as a medium for torque transmission by the vane pump 3.

The thrust bearing 20 includes a washer 20a with a flange fitted into a recess 9a of the side plate 9 of the vane pump 3,
It is a needle hair ring that holds a plurality of needles 20c by a retainer 20b, and transmits the thrust load due to the pressure from the side plate 9 to the actuation member 43 of the multi-disc clutch 4.
Smooth relative rotation with.

Figure 1, and Figures 3 and 4 showing the principle of internal pressure generation.
Referring to the figure, the vane pump 3 includes a rotor 31 and a pair of site plates 9.
A cam ring 32 is sandwiched between the rotor 31 and the cam ring 32, which forms a plurality of pump chambers between the cam ring 32 and the rotor 31.
The main part is separated by a plurality of vanes 34 which are pressed against the inner surface of the pump chamber 2 and partition the pump chamber into working chambers A and B, and a plurality of pairs of check valves 35 and 36 consisting of Paul valves and the like corresponding to the working chambers A and B. It is configured.

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 is opened between the mounting positions of the adjacent vanes 34 on the outer circumferential surface of the main body of the rotor 31, and has a predetermined depth in the radial direction. are connected in the axial direction to an annular groove 31c formed on the side surface of the main body of the rotor 31 through separate oil guide holes 31b. Allows only oil to flow into the pump chamber from

In addition, in FIGS. 3 and 4, the check valve 35
．． 36 is schematically disposed within the cam ring 32 for the sake of explanation. Further, the coil spring 33 is not shown.

The rotor 31 is spline-coupled to the right front wheel drive shaft through the rotation shaft 2 so as to be integrally rotatable therewith.
It is movable in the axial direction. Cam ring 32, side plate 9. The IO is integrally rotatably connected by a port 37.

A space between the side plate 10 and the first Uji puffer 11 is provided to restrict the relative rotation between the side plate 10 and the first Uzi puffer 11, and to prevent the side plate 10 from increasing when the transmitted torque by the vane pump 3 increases. The above-mentioned cam mechanism 5 that presses toward the plate clutch 4 side is interposed.

The cam ring 32 rotates integrally with the left front wheel drive shaft via the housing l and the cam mechanism 5. As shown in FIG. 3, the vane 34 is provided with an orifice 34a that allows oil to flow between the working chamber B and the working chamber partitioned by the vane 34. Between the side plate 9 and the rotating shaft 2, and between the side plate 10 and the rotating shaft 2
Seals 64 and 65 allow for relative movement while maintaining a liquid-tight state.

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

As a result, a high pressure is generated in the working chamber A, which pushes the vane 34 or the cam ring 32, and 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 on the side that has slipped to the left front wheel drive shaft on the non-slip side, and torque is automatically distributed to ensure grip on the road surface.

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

Figure 4 shows that when the left front wheel slips and the left front wheel drive shaft rotates faster than the right front wheel drive shaft, the cam ring 3
2 shows a state of clockwise rotation relative to the rotor 31. In this case, since the vane 34 advances in the direction of the working chamber B, high pressure is generated in the working chamber B.
Torque is transmitted from the left front wheel drive shaft to the right front wheel drive shaft R via this high pressure. Note that the check valve 35 is closed, and the check valve 36 is opened, so that oil is supplied from the housing portion 8 to the working chamber A through the check valve 36.

The multi-plate clutch 4 includes a plurality of outer plates 41 spline-coupled to a first housing, and a distal end 2 of a rotating shaft 2.
the actuating member 43 spline-coupled to a and movable in the axial direction; the inner plates 42 spline-coupled to the actuating member 43 and alternately combined with the outer plate 41; the second housing 12 and the actuating member 43;
The disc spring 44 is interposed between the plate spring 44 and biases the plates 41 and 42 in a direction to separate them.

Referring to FIG. 1, the cam mechanism 5 includes a cam member 51 fixed to the side surface of the side plate 10 by a bolt 53, and a cam member 51 fixed to the inner surface of the first housing 11 by a bolt 54. cam member 5
2, and both cam members 51 and 52 have bolts 5
3.54 is loosened so that it can be replaced with one of other specifications.

Referring to FIGS. 5 to 8, the cam member 51 has four cam portions 51a formed in a wave shape along the circumference, and this cam portion 51a is connected to the cam portion 51a. It is engaged with a cam portion 52a of a cam member 52, which is formed to protrude in a similar wave shape. This cam mechanism 5 includes an operating member 43,
Since the axial biasing force of the disc spring 44 is acting through the thrust bearing 2o and the vane pump 3, the rotating shaft 2o
In a state where the rotational speed difference between the housing 1 and the housing 1 is small, the cam portion 51a and the cam portion 52a are
They are combined as shown in the figure.

The cam portion 51a and the cam portion 52a then increase the axial distance between them by causing a relative shift in the rotation direction as shown in FIG. Move away from the vane pump 3 against the disc spring 44.
is pressed toward the multi-disc clutch 4 side. In addition, Figures 5 and 6
In the figure, 51b and 52b are bolt mounting holes;
1c and 52C are bolt seats.

According to this embodiment, when the rotation speed difference between both the left front wheel drive shaft and the right front wheel drive shaft, that is, between the housing l and the rotating shaft 2 is small, the vane pump 3 transmits torque between them. or is being done. Then, when the rotation speed difference becomes larger than a predetermined value, the cam mechanism 5
The vane pump 3 is moved to the multi-disc clutch 4 side, and the outer plate 4 of the multi-disc clutch 4 is moved by the side plate 9.
1 and the inner plate 42 are brought into pressure contact with each other to directly connect the left front wheel drive shaft and the right front wheel drive shaft. Thereby, as shown by the solid line in FIG. 9, 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 rapid increase in torque is achieved mechanically by the cam mechanism 5, and is not achieved by an explosive increase in internal pressure as in viscous couplings, which is not achieved by viscous couplings. It is possible to solve the problem of deterioration of durability caused by an increase in internal pressure. In this way, the drawbacks of viscous coupling and differential pump type devices can be solved all at once.

Furthermore, since the thrust bearing 20 is interposed between both the multi-disc clutch 4 and the vane pump 3, the generation of sliding friction between the two due to the relative rotation of the two can be suppressed by the thrust bearing 20. The transmission torque between the re-driving shafts due to the addition of friction torque can be significantly reduced (for example, from the dashed line to the solid line in FIG. 9), especially in the low-speed rotation range.

Furthermore, by removing the cam members 51 and 52 of the cam mechanism 5 from the side plate 10 and the first housing 11 and replacing them with those of other specifications having different cam shapes, the pressing force of the vane pump 3 on the multi-disc clutch 4 can be increased. can be varied, thereby making it possible to adjust the rise characteristic of the transmitted torque as shown, for example, by the broken line in FIG. Note that the above-mentioned rising characteristic can also be adjusted by adjusting the biasing force of the disc spring 44.

Furthermore, a vane pump 3 is provided in the housing portion 8 of the housing 1.
and the multi-disc clutch 4 are housed together, and the oil sealed in the accommodation section 8 is provided for lubrication between each plate 41, 42 of the multi-disc clutch 4, and is also circulated and supplied to the inside of the vane pump 3. Since there is no need to provide a separate oil tank, the structure can be simplified.

Further, since both plates 41 and 42 of the multi-plate clutch 4 are arranged outside the vane pump 3, the axial dimension of the entire device can be shortened.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, the cam mechanism can be configured as a pole cam mechanism in which a pawl is interposed between a pair of cam members.

Furthermore, a slide metal can be used as the thrust bearing.

Further, the present invention further includes the use of this driving force transmission device for torque transmission between a propulsion shaft and a rear wheel drive shaft, the use of torque transmission between a left rear wheel drive shaft and a right rear wheel drive shaft, etc. Various design changes can be made without changing the gist of the invention.

<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 increase in torque is done mechanically by a cam mechanism and is not done by an explosive increase in internal pressure as in a viscous coupling, so there is no deterioration in durability.

In addition, the thrust bearing interposed between the multi-disc clutch and the differential pump can suppress the generation of sliding friction between the two due to the relative rotation of the two, and the addition of friction torque between the re-driving shafts can be suppressed. The transmitted torque can be significantly reduced, especially in the low speed rotation range, and the vehicle can smoothly make sharp turns when driving at low speeds.

Furthermore, if the cam mechanism has a pair of removable cam members, these cam members can be removed from the housing and vane pump and replaced with one of another specification with a different cam shape to improve the differential. The pressure force of the pump on the multi-disc clutch side can be varied, thereby
This has the unique effect of making it possible to easily adjust the rise characteristics of the transmitted torque.

[Brief explanation of the drawing]

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, Fig. 2 is a schematic sectional view showing a thrust bearing, and Figs. 3 and 4 show the function of a vane pump, respectively. 5 and 6 are plan views of the cam member, and FIGS. 7 and 8 are schematic cross-sectional views.
The figure is a schematic diagram showing the engagement state of the cam member, and FIG. 9 is a diagram showing the relationship between the rotational speed difference and the transmitted torque. DESCRIPTION OF SYMBOLS 1... Housing, 2... Rotating shaft, 3... Vane pump 4... Multi-plate clutch, (differential pump) 5... Cam mechanism, 51. 2...Cam member.

Claims (1)

[Claims] 1. A housing that rotates in conjunction with one of a pair of drive shafts; a rotating shaft that rotates in conjunction with the other drive shaft and is rotatable relative to the housing; the housing and the rotation; a differential pump which is interposed between both the shafts and is movable in the axial direction of the rotating shaft, and which transmits torque between the two by hydraulic pressure generated according to the difference in rotational speed between the two; , a multi-disc clutch that is interposed between the two and is disposed adjacent to the differential pump, and is pressed by the differential pump to frictionally engage and transmit torque between the two, and the differential pump and The cam mechanism connects the housing so as to be integrally rotatable and presses the differential pump toward the multi-disc clutch as the transmission torque by the differential pump increases, and the cam mechanism is provided between the multi-disc clutch and the differential pump. A driving force transmission device for a four-wheel drive vehicle characterized by interposing a thrust bearing that reduces friction caused by relative rotation between a multi-plate clutch and a differential pump. 2. The driving force transmission device for a four-wheel drive vehicle according to claim 1, wherein the cam mechanism includes a pair of cam members removably attached to the housing and the vane pump, respectively.