JPH03253423A - Four-wheel drive vehicle drive force transmitting device - Google Patents

Abstract

PURPOSE:To better a temperature characteristic of transmission torque and also heighten a performance at the time of emergency such as an escaping performance or the like, by providing within an oil chamber a multi-plate clutch which connects directly a casing to a rotary shaft by means of the heat expansion of oil. CONSTITUTION:In the case of a rotation number difference between both drive shafts being small or an oil temperature having not risen much due to a short time operation, the transmission of torque between both drive shafts is conducted mainly through the oil pressure of a pump chamber 22. And in the case of the rotation number difference having become rapidly large or the oil temperature having risen due to a long time operation, a multi-plate clutch 4 is made to be pressingly contacted by means of what is called a hump phenomenon due to the heat expansion of oil within an oil chamber 3, and a casing 10 is directly connected to a rotary shaft 6, and as a result, both drive shafts can be directly connected.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to the following:1. The present invention relates to a driving force transmission device for a four-wheel drive vehicle that transmits driving force between a left front drive shaft and a right front drive shaft, or between a left rear drive shaft and a right rear drive shaft.

<Prior Art> Four-wheel drive vehicles have become rapidly popular in recent years because they have excellent ability to travel on rough roads, as well as excellent acceleration and driving stability on ordinary roads.

Conventionally, in this four-wheel drive vehicle, a front wheel drive shaft and a rear wheel drive shaft have been rigidly coupled.

However, if this causes a difference in the rotational speed of the front and 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 speed will be affected. There was a problem in that a so-called tight corner braking phenomenon occurred, in which the inner rear wheel was dragged in a slipping state, causing the vehicle to wobble. In order to solve these difficulties, current four-wheel drive vehicles use a driving force transmission method between both drive shafts that allows for a difference in rotation speed between the two drive shafts and transmits torque according to this difference in rotation speed. A device is involved.

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

The above VCU has a large number of inch plates that rotate together with one drive shaft, 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 the frictional force between the oil interposed therebetween and the shearing force due to the viscosity of the oil, and torque is transmitted. When the rotational speed difference between the two is greater than a predetermined value, the oil is agitated and undergoes explosive thermal expansion, which presses the two plates together and directly connects the drive shafts, rapidly increasing the transmitted torque. raise (hump phenomenon).

On the other hand, in the above-mentioned hydraulic pump type device, a vane-equipped rotor that rotates with either of the drive shafts is disposed coaxially with the rotor and inside a cam ring of a casing that rotates with the other drive shaft. It consists of The rotor and the cam ring are connected via an original groove interposed between them, and torque is transmitted between both drive shafts.

In principle, this transmitted torque increases as the pressure generated by the vane pump increases, that is, as the rotation speed difference between both drive shafts increases. Note that the vane is provided with an orifice for adjusting the generated pressure.

<Problems to be Solved by the Invention> By the way, when a VCU or hydraulic pump type device is operated for a long time, the oil becomes hot and the viscosity of the oil decreases, resulting in a decrease in the transmission torque with respect to the difference in rotational speed.

In the case of a VCU, torque is transmitted through viscosity, so
Although it has the disadvantage that it is directly affected by this decrease in viscosity and the transmission torque decreases sharply at high temperatures, it has the advantage of excellent performance in emergencies by utilizing the hump phenomenon described above. In other words, in the VCU, when the oil temperature rises due to long-term operation, for example, the hump phenomenon can be used to directly connect both driving wheels to eliminate the difference in rotation speed. It has the advantage of being able to avoid abnormal increases.

In addition, when one tire is spinning, it is possible to directly connect both driving wheels due to the knock phenomenon and transmit the maximum torque to the other tire that is not slipping, improving escape performance in an emergency such as a wheel coming off. Another advantage is that it can be made higher.

On the other hand, in the case of a hydraulic pump type device, it has a higher heat dissipation effect than a VCU due to its structure, and the oil is less likely to reach high temperatures.
Since it is less susceptible to viscosity reduction like U, it has the advantage of reducing the transmission torque at high temperatures, but since both driving wheels cannot be directly connected, in terms of emergency performance such as escape performance, VCU was inferior to

The purpose of this invention is to provide a driving force transmission device for a four-wheel drive vehicle that solves the drawbacks of both types at once, has good temperature characteristics of transmitted torque, and has excellent emergency performance such as escape performance. shall be.

Means for Solving the Problems> In order to achieve the above object distantly, a driving force transmission device for a four-wheel drive vehicle according to the present invention includes a casing that rotates in conjunction with one of a pair of drive shafts, and a casing that rotates in conjunction with the other of a pair of drive shafts. A pump chamber that generates hydraulic pressure to connect both drive shafts according to the rotational speed difference between the two drive shafts, and an oil chamber that seals oil are installed in parallel between the rotating shaft. The present invention is characterized in that it is equipped with a multi-disc clutch that can directly connect the casing and the rotating shaft through thermal expansion of oil.

According to the driving force transmission device for a four-wheel drive vehicle with the above configuration, the rotation speed difference between the two drive shafts is small, or the operation occurs for a short time.
When the oil temperature has not risen much, torque is transmitted between the two drive shafts mainly via the oil pressure in the pump chamber. If the above-mentioned rotational speed difference suddenly increases or the oil temperature rises due to long-term operation, the multi-disc clutch will be brought into pressure contact due to the so-called hump phenomenon caused by thermal expansion of the oil in the oil chamber. , the casing and the rotating shaft are directly connected, thereby making it possible to directly connect both drive shafts.

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

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 has a front wheel drive shaft and a rear wheel drive shaft. between the casing 10, which rotates in conjunction with the front wheel drive shaft, and the hollow rotary shaft 6, which rotates in conjunction with the rear wheel drive shaft via the output shaft 2, that is, between both drive shafts. A vane pump 1 serving as a hydraulic pump and a multi-disc clutch 4 disposed within an oil chamber 3 are arranged in parallel on a drive transmission path between the two.

The casing 10 of the present driving force transmission device includes a cam ring 12 that constitutes a part of the vane pump 1, side plates 17 and 18, and a housing 8 of the oil chamber 3.

With reference to FIG. 1 and FIG. 2 showing the principle of internal pressure generation,
The vane pump 1 includes a rotor 11, a cam ring 12 containing the rotor 11, a pump chamber 22 between the cam ring 12 and the rotor 11, and a pair of side plates 17 that rotate integrally with the cam ring 12.
．． 18. A vane 14 protrudes from the groove 118 on the outer periphery of the rotor 1, is pressed against the inner surface of the cam ring 12 by the coil spring 13, and divides the pump chamber 22 into working chambers A and B;
Check valve 1 consisting of a ball valve communicating with working chambers A and B
5, 16, and a pair of check valves (not shown) consisting of ball valves communicating with the bottom of the groove 11a.

The rotor 11 is splined to the rotating shaft 6 and rotates together with the rear wheel drive shaft. 21 is a bearing that supports the output shaft 2. The cam ring 12 and the side plates 17, 18 are configured to rotate together with the front wheel drive shaft via the gear 5 and a gear portion 17a formed on the side plate 17.

A seal is provided between the cam ring 12 and each side plate 17, 18 by an O-ring 61, 62, respectively. Between the rotating shaft 6 and each side plate 17.18,
It is sealed by a pair of oil seals 63 and 64, thereby sealing oil inside the vane pump 1. 1
Reference numeral 9 denotes a passage for sealing oil in the vane pump 1, which is sealed by a tapered screw 20.

The vane 14 is provided with an orifice 14a that allows oil to flow between a working chamber A and a working chamber B partitioned by the vane 14.

The function of the vane pump will be explained with reference to FIG. For example, if the front wheels slip and the front wheel drive shaft rotates faster than the rear wheel drive shaft, the rotor 11 will rotate clockwise in the figure relative to the cam ring 12, and the vanes 14 will be activated. Proceed in the direction of room B. At this time, the oil cannot move smoothly from the working chamber B to the working chamber A because the orifice 14a of the vane 14 has a small diameter. Therefore, the oil in the working chamber B tends to flow into the oil tank 9, but this is prevented by the check valve 15. As a result, high pressure is generated in the working chamber B, and the vane 14 pushes the cam ring 12 through this high pressure.
Torque is transmitted from the rotor 11 to the cam ring 12.

That is, torque is transmitted from the front wheel drive shaft on the slipping side to the rear wheel drive shaft on the non-slip side, and torque is automatically distributed to ensure grip on the road surface.

The above-mentioned pressure is large because the rotational speed difference between the rotor 11 and the cam ring 12 is large, and a torque corresponding to the rotational speed difference is transmitted between both drive shafts.

Further, oil is supplied to the working chamber A from the oil tank 19 via the open check valve 16b.

The grooves 118 that accommodate the vanes 14 communicate with each other, and the working chambers A and B communicate with the bottom of the groove 11a via a pair of check valves (not shown). Therefore, high-pressure oil generated in the working chamber B is supplied to this groove 11a via one of the check valves, and the vane 14 is pressed against the inner wall of the cam ring 12.
The adhesion of No. 4 is improved. At this time, the other check valve prevents the pressure in the low-pressure working chamber A from increasing.

The oil chamber 3 is formed between a side plate 18 and a housing 8, which constitute a part of the casing 10, and the rotating shaft 6. The bolt 7 passes through and connects the side plate 17, cam ring 12, side plate 18, and housing 8, and integrates the casing 10. 31
is a passage for sealing oil into the oil chamber 3, and the ball 3
1 is caulked and sealed.

The multi-plate clutch 4 includes a plurality of outer plates 41 spline-coupled to the housing 8 and inner plates 42 spline-coupled to the rotating shaft 6 and alternately combined with the outer plates 41. The outer plate 41 rotates in conjunction with the front wheel drive shaft via the casing 10, and the inner plate 42 rotates in conjunction with the rear wheel drive shaft through the rotating shaft 6 and the output shaft 2.

The oil chamber 3 is filled with oil such as silicone oil similar to that of the internal VCU, and the viscosity of the oil interposed between the outer plate 41 and the inch plate 42 reduces the torque between both drive shafts. Although the transmission takes place, the sealing rate and viscosity of the oil sealed in the oil chamber 3 are low compared to the VCLI in the membrane. Therefore, the multi-plate clutch 4
As shown in FIG. 3, the transmission characteristic of is that a substantially constant transmission torque is transmitted as the rotational speed difference increases, and the transmission torque Q by this multi-disc clutch 4 is -
Compared to the VCU transmission torque S within the membrane, 1/3 to 17
It is preferable to set it to about 5, and the encapsulation rate and oil viscosity to achieve this are appropriately selected.

Referring to FIG. 3, the transmission torque characteristic of this drive transmission device is transmission torque R, which is the sum of transmission torque P by vane pump 1 and transmission torque Q by multi-disc clutch 4.

According to this embodiment, in case of internal use, that is, when the rotational speed difference is small or the oil temperature does not rise much due to short-time operation, the oil pressure is mainly used via the oil pressure in the pump chamber 22 of the vane pump 1 , torque is transmitted between both drive shafts.

When the temperature of the oil in the oil chamber 3 increases due to emergency use, for example, when the difference in rotation speed increases suddenly due to the occurrence of a wheel coming off, or due to long-term operation, the temperature of the oil inside the oil chamber 3 increases. Thermal expansion of the oil causes a so-called hump phenomenon, causing the multi-disc clutch 4 to come into pressure contact with the casing 10 and the rotating shaft 6.
It is possible to directly connect both drive shafts, thereby maximizing the transmitted torque and improving escape performance. In this way, in internal use, torque is transmitted by a hydraulic pump-type device that is superior to a VCU, and in an emergency, it is possible to obtain the crisis avoidance performance of a VCU, while using a conventional hydraulic pump-type device. By eliminating the drawbacks of both the VCU and the VCU, it is possible to realize a driving force transmission device for a four-wheel drive vehicle that is superior to either of the two.

Note that the present invention is not limited to the above-described embodiment, and for example, the torque transmission characteristics of the multi-disc clutch 4 can be adjusted by adjusting the clearance between the outer plate 41 and the inner plate 42 of the multi-disc clutch 4. can be adjusted.

In addition, this driving force transmission device can be used for torque transmission between the left rear wheel drive shaft and the right rear wheel drive shaft, or between the left rear wheel drive shaft and the right rear wheel drive shaft, and as a hydraulic pump. Various design changes can be made without changing the gist of the invention, such as using a trochoid pump or other gear pump.

<Effects of the Invention> As described above, according to the present invention, when used within a membrane,
Since torque is transmitted mainly through the oil pressure in the pump chamber, the temperature characteristics of the transmitted torque are good.In addition, in an emergency, the multi-disc clutch can be directly connected by thermal expansion of the oil in the oil chamber, and both drive shafts can be directly connected. However, with this, a crisis can be avoided. Therefore, the drawbacks of both the conventional hydraulic pump type device and VCU are eliminated, and
This has the unique effect of realizing a driving force transmission device for a four-wheel drive vehicle that is superior to either of the two.

[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, Fig. 2 is a schematic sectional view showing the operation of a vane pump, and Fig. 3 is the relationship between the rotational speed difference and the transmission torque. FIG. 1... Vane pump (hydraulic pump) 3... Oil chamber, 4... Multi-plate clutch, 0... Casing, 2... Pump chamber.

Claims (1)

[Claims] 1. A casing that rotates in conjunction with one of a pair of drive shafts,
A pump chamber that generates hydraulic pressure to connect both drive shafts according to the difference in rotational speed between the two drive shafts, and an oil chamber that seals oil are installed in parallel between the other rotating shaft and the rotating shaft that rotates in conjunction with the other. A driving force transmission device for a four-wheel drive vehicle, characterized in that the oil chamber is provided with a multi-plate clutch that can directly connect the casing and the rotating shaft by thermal expansion of oil.