JPH0818500B2 - Front and rear wheel drive system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front and rear wheel drive system for a vehicle equipped with a transmission having a speed increasing function for the rear wheel side rotation speed during turning, and particularly to a transmission. The present invention relates to configurations of a speed increasing clutch and a constant speed clutch.

[Prior Art] As shown in FIG. 1, front and rear wheels provided with controllable controllable clutches 11 _L and 11 _R for the left and right wheels on the rear wheel side to independently vary the driving force transmission rate from the engine. In a drive (hereinafter abbreviated as 4WD) vehicle, a transmission device 15 for changing the average rotation speed of the front wheels and the average rotation speed of the rear wheels to a constant speed / increased speed is provided in a power transmission path from the engine to the rear wheels. When going straight, the average speed of the front and rear wheels is kept the same.When turning, the average speed of the rear wheels is made higher than that of the front wheels, and the clutch with control (either 11 _L or 11 _R ) on the outside of the turning of the rear wheels is used. There is an attempt to enhance the turning performance of a 4WD vehicle by making the fastening force stronger than the inside of the turn (see Japanese Patent Application No. 63-7845 proposed by the applicant).

Here, the transmission device 15 disposed between the front and rear divided propulsion shafts 7 and 8 includes a speed increasing gear train 16, a constant speed clutch 17 and a speed increasing clutch 18, both of which are hydraulic multi-plate clutches. Turn on the constant speed clutch 17 and turn on the speed increasing clutch 18.
When turned off, the constant speed rotation is transmitted, and conversely the constant speed clutch 1
When 7 is turned off and the speed increasing clutch 18 is turned on, the increased speed rotation is transmitted.

[Problems to be Solved by the Invention] By the way, in the one proposed in Japanese Patent Application No. 63-7845,
At the time of switching between constant speed / acceleration, both clutches 17 and 18 were delicately controlled, that is, shifting was performed while sliding both clutches 17 and 18, so that heat generated in both clutches 17 and 18 was generated. There was difficulty in controlling the shift.

Therefore, the object of the present invention is to provide a 4WD vehicle as described above,
It is an object of the present invention to provide a structure of a transmission that switches between constant speed / acceleration and a 4WD device capable of simplifying clutch control.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a first power transmission path for transmitting power from a power source to the front wheel side and a second power transmission path for transmitting power to the rear wheel side. The first connecting clutch that has the same rotational speed on the front wheel side and the rotational speed on the rear wheel side in the second power transmission path from the power source to the rear wheel side, and the rotational speed on the rear wheel side more than the rotational speed on the front wheel side. In a 4WD device for a vehicle including a speed change device having a second connecting clutch for increasing the transmission, the second connecting clutch is a controllable clutch capable of controlling connection and disconnection, and the first connecting clutch is rearward from the front wheel side. It is characterized by a one-way clutch that can transmit rotation to the wheels.

[Operation] The second connecting clutch for increasing the speed of the rear wheel provided in the transmission is a controllable clutch that can be connected / disconnected, and the first connecting clutch for constant speed is capable of transmitting rotation from the front wheel side to the rear wheel side. Since a one-way clutch is used, there is no need to control the constant-velocity clutch.
Speed changeover control can be performed, and shift control can be simplified.

Moreover, the device itself can be simplified and reduced in size by adopting the one-way clutch.

Also, because one of the clutches is a one-way clutch, the connection between constant speed / acceleration is smooth and shift shock is reduced.

When using the one-way clutch for constant speed, the front wheel side brake torque when the brake is operated is not transmitted to the rear wheels, and the running stability of the vehicle due to the rear wheel lock caused by the transmission of the excessive braking force is improved. There is no loss.

[Example] An example will be described below with reference to the accompanying drawings.

The present invention will be described in the following embodiments as an improvement of the transmission 15 or the rear differential device 10 in the 4WD vehicle shown in FIG.

First, in the 4WD vehicle of FIG. 1, the rotational driving force is transmitted from the engine 1 to the left and right front wheels 5 _L and 5 _R via the transmission 2, the gear train 3, and the front differential device 4. Then, from the front differential device 4, the gear train 6, the propulsion shaft 7, the transmission device
The rotational driving force is also transmitted to the rear differential device 10 via the propeller shaft 8, the gear train 9, and the rear differential device 10. Further, from the rear differential device 10, the clutches 11 _L and 11 with variable torque transmission capacity by the built-in hydraulic multi-plate clutch are provided. Left and right rear wheels via _R and drive shaft 12 _L , 12 _R
The rotational driving force is transmitted to 13 _L and 13 _R. As described above, the first power transmission path for transmitting the power from the power source to the front wheel side and the second power transmission path for transmitting the power to the rear wheel side are configured.

The transmission 20 shown in FIG. 2 according to the first embodiment of the present invention.
Is an improved structure of the transmission 15, and in FIG.
Reference numeral 21 is an apparatus case, 22 is an input shaft, 23 is an output shaft, and 24 is an intermediate shaft. A speed increaser 25 is configured between the input shaft 22, the output shaft 23, and the intermediate shaft 24, and the speed increaser 25 is a gear integrated with the rear end of the input shaft 22.
26 and gears 27, 28 which are integrated in front of and behind the output shaft 23, and a gear 29 located on the output shaft 23 side. This final gear 29 and output shaft 23
A control multiple clutch 31 for increasing the speed of the rear wheel by a hydraulic multi-plate clutch is formed between and.

The controllable clutch 31 includes an inner hub 33 integrated with the final gear 29 mounted on the intermediate portion of the output shaft 23 through a ball bearing 32, and an outer hub integrated with the front portion of the output shaft 23 by serration fitting or the like. A large number of inner plates 35 and outer plates 36 are arranged alternately with each other in the axial direction. In addition, the piston 3
7, a hydraulic chamber 38 and a return spring 39 are provided.

A one-way clutch 41 is formed between the outer hub 34 of the controllable clutch 31 and the gear 26 at the rear end of the input shaft 22. The one-way clutch 41 is for constant velocity of the front and rear wheels, which is capable of transmitting a rotational force from the input shaft 22 to the output shaft 23 when the 4WD vehicle travels forward.

In the controllable clutch 31, a radial oil passage 42, an axial oil passage 43, a radial oil passage 44, and an outer hub in the output shaft 23 from an oil source (not shown) via an oil passage in the device case 21.
Piston hydraulic oil is supplied to the hydraulic chamber 38 from the diagonal oil passage 45 on the inner peripheral side, and the fastening force between the inner plates 35 and the outer plates 36 is obtained by the rightward movement of the piston 37 in the drawing.

If the transmission 20 as described above is provided in the power transmission path from the power source of the 4WD vehicle shown in FIG. 1 to the rear wheel side, the clutch 31 for speed-up control of the transmission 20 is turned off during straight traveling. The input shaft 22 to the one-way clutch 41 to the outer hub
The rotation is transmitted to the output shaft 23 via 34. Further rear differential device
Clutch with dual control of left and right torque transmission capacity within 10
By maintaining the fastening force of 11 _L and 11 _R evenly, the stability of straight running, especially the high-speed stability can be improved.

During turning, the speed increasing control clutch 31 of the transmission 20 is turned on to turn the speed increasing device 25, that is, the input shaft 22.
From the gear 26, the gears 27, 28, and the gear 29, the ON state controllable clutch 31 is radially transmitted to the output shaft 23. in this case,
Turning performance can be improved by setting the engagement force of the left and right variable torque transmission capacity controllable clutches 11 _L and 11 _R in the rear differential device 10 to the one on the outside of the turn to increase the driving force distribution. To be enhanced.

It is also possible to perform control to increase stability by increasing the driving force distribution on the inner wheel side during high-speed turning.

As described above, it is possible to contribute to the improvement of the movement performance of the vehicle.

In the transmission 20, the rear wheel speed increasing clutch is the controlled clutch 31, but for the constant speed motor, the one-way clutch 41 capable of transmitting the rotation from the front wheel side to the rear wheel side is adopted. Since it is not necessary to control the one-way clutch 41, it is possible to perform constant velocity / acceleration switching control by controlling only the speed increasing clutch 31. Therefore, the constant speed clutch 17 shown in FIG. The shift control can be simplified as compared with the one requiring.

Moreover, by adopting the one-way clutch 41 instead of the conventional controllable clutch 17, the device structure can be simplified and downsized.

Further, since the one-way clutch 41 can smoothly obtain the constant speed / acceleration connection, the shock at the time of shifting is reduced.

When the one-way clutch 41 for constant speed is used, the front-wheel brake torque when the brake is operated is not transmitted to the rear wheels, so that the vehicle travels due to the rear-wheel lock caused by the excessive braking force transmission. Stability will not be lost.

Next, a second embodiment of the improved structure of the rear differential device 10 shown in FIG. 1 will be described with reference to FIG.

The transmission 50 of the second embodiment is constructed between the controllable clutches 11 _L , 11 _R of the torque differential displacement type of the rear differential device 10.

That is, a pair of left and right planetary gear mechanisms 53 _L , 53 _R is formed between the differential case 51 and the main shaft 52, and each planetary gear mechanism 53 _L , 5 _R is formed.
3 _R is a ring gear 54 _L , 54 _R integrated with the inner circumference of the differential case 51.
And a plurality of sets of planetary gears 55 _L , 55 that mesh with the inside
_It is composed of _R and sun gears 56 _L and 56 _R which mesh with the inside thereof.

In the embodiment, the left planetary gear mechanism 53 _L is used for speed-up, and the right planetary gear mechanism 53 _R is used for constant speed.The gear ratios are set so that both planetary gears 55 _L , 55 _R are Supported by a common carrier 57, the carrier 27 is integrated with the main shaft 52. Further, rotation can be transmitted from the main shaft 52 to the controllable clutches 11 _L and 11 _R of the variable torque transmission capacity type.

And with the sun gear 56 _L by the same control with the clutch 58 which can be fixed rotation are provided in the planetary gear mechanism 53 _L for accelerating the rotation of the sun gear 56 _R in constant speed planetary gear mechanism 53 _R A one-way clutch 59 is provided which can be fixed only during forward rotation transmission during non-braking.

The transmission 50 described above can also provide the same function as that of the transmission 20 of the first embodiment.

The present invention can be used not only in the front wheel drive-based 4WD vehicle of the embodiment but also in the rear wheel drive-based 4WD vehicle and the 4WD vehicle in which the driving force is transmitted to the front and rear wheels via the center differential.

[Effects of the Invention] As described above, according to the 4WD device of the present invention, the constant speed clutch is changed from the front wheel side to the rear wheel side as a controllable clutch for the rear wheel speed increasing clutch of the transmission. Since it is a one-way clutch that can transmit rotation to, it is possible to perform constant speed / acceleration switching control by controlling only the speed-up clutch, thus simplifying gear shift control and adopting a one-way clutch to improve the device structure. It can be simplified and reduced, and the one-way clutch can be used to smooth the connection between constant speed / acceleration and reduce shift shock, and the use of the one-way clutch can reduce rear shock caused by excessive braking force from the front wheels. It is also possible to prevent wheel lock and ensure vehicle running stability.

[Brief description of drawings]

FIG. 1 shows an example including a transmission according to the prior art.
FIG. 2 is a configuration diagram of a drive system of a 4WD vehicle, FIG. 2 is a cross-sectional plan view showing the internal structure of the transmission according to the first embodiment of the present invention, and FIG. 3 is a rear differential device incorporating the transmission according to the second embodiment. 2 is a schematic configuration diagram of FIG. In the drawings, 20 and 50 are transmissions of the present invention, 31 and 58 are control clutches, and 41 and 59 are one-way clutches.

Claims (1)

[Claims] 1. A first transmission for transmitting power from a power source to a front wheel side.
It has a power transmission path and a second power transmission path for transmitting to the rear wheel side, and equalizes the rotation speed on the front wheel side and the rotation speed on the rear wheel side in the second power transmission path from the power source to the rear wheel side. A front / rear wheel drive system for a vehicle, comprising: a transmission including a first connecting clutch and a second connecting clutch for increasing a rotational speed on a rear wheel side relative to a rotational speed on a front wheel side, the connection / disconnection control of the second connecting clutch. A front-rear wheel drive device for a vehicle, wherein the first connecting clutch is a one-way clutch capable of transmitting rotation from a front wheel side to a rear wheel side while using a controllable clutch.