JPH0538961A - Four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To provide a four-wheel drive (4WD) vehicle allowing a differential gear and a propeller shaft to be dispensed with and capable of escaping easily from a slip even with the generation of the slip to one or both of two lateral wheels driven by a main motor. CONSTITUTION:Hydraulic pumps 4a, 4b are respectively mounted to lateral front wheels 3a, 3b driven by a main motor 1, and hydraulic pumps 5a, 5b are respectively mounted to lateral rear wheels 6a, 6b. The diagonally opposed hydraulic pumps 4a, 4b and 5a, 5b are mutually communicated by hydraulic circuits 8a, 8b, and the hydraulic circuits 8a, 8b are provided with flow control valves 7a, 7b. The flow control valves 7a, 7b are controlled by a controller 9 receiving signals from a steering angle sensor 10 and a vehicle speed sensor 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a four-wheel drive vehicle.

[0002]

2. Description of the Related Art In recent years, four-wheel drive vehicles (hereinafter referred to as 4WD vehicles) have been rapidly adopted for passenger cars along with the diversification of automobile applications. By the way, there is a part-time 4WD (often used in leisure vehicles and off-loaders) that mechanically connects four wheels as a drive method for a 4WD vehicle, but since the four wheels are mechanically connected, this 4WD vehicle is used on a paved road or the like. The mechanical connection type 4WD is unsuitable for passenger cars and the like because various problems occur when traveling in a place having a high road surface friction coefficient or when the rotation speed of each wheel is different such as when turning.

Therefore, viscous coupling (VCU)
A full-time 4WD is used for passenger cars as a method of transmitting driving force when there is a difference in rotation between the front and rear wheels by utilizing the viscosity of liquid such as oil and hydrocoupling (HCU). The driving force is not transmitted unless there is a rotation difference between the two wheels due to the structure and the other two wheels, so the road surface friction coefficient is low. For example, the two wheels start to slip once while turning on a frozen road. As a result, you will not be able to control and you will not be able to take advantage of the 4WD. or,
Regardless of whether the structure is part-time 4WD or full-time 4WD, the weight of the system increases due to the installation of the transfer, propeller shaft, drive shaft, etc. The above-mentioned 4WD system is a passenger car where fuel efficiency and exercise performance are important. Not suitable for.

Therefore, in Japanese Patent Laid-Open No. 3-356, a hydraulic pump and a hydraulic motor are used to transmit power between the front wheels and the rear wheels instead of the heavy propeller shaft. In this method, the rear wheels are driven when the front wheels start to slip, so it may be possible to control so that only the front wheels slip and thus become uncontrollable, but it is driven by a hydraulic motor. It is necessary to mount heavy items such as differential gears and drive shafts on the rear wheels. Furthermore, for example, when the left end of the road is muddy and the driving force of the engine cannot be transmitted to the wheels, the left and right front wheels slip, and the right front and rear wheels are not driven at all.
This is equivalent to an incomplete 4WD drive in which differential lock is impossible.

[0005]

SUMMARY OF THE INVENTION The present invention provides a four-wheel drive vehicle that does not require a differential gear, a propeller shaft, or the like and can easily escape from the slip even if one or both of the left and right wheels of the main engine drive slip. The challenge is to provide.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention has a hydraulic pump mounted on each of the left and right two wheels of a prime mover or its drive shaft, and the other two left and right wheels or its drive shaft. A hydraulic motor is attached to each of the above, and the hydraulic pump and the hydraulic motor, which are diagonally opposed to each other, are connected to each other via a hydraulic circuit.

[0007]

The hydraulic pump is rotationally driven by the wheels of the prime mover or its drive shaft, and the generated power is transmitted to the hydraulic motor diagonally opposed to the hydraulic pump.
The other two wheels are rotationally driven by a hydraulic motor. Therefore, if the drive wheels of the main engine are front wheels, for example, even if one or both of the front wheels slip, the rear wheels diagonally opposed to the front wheels are rotationally driven by the hydraulic motor, and the vehicle body escapes from the slip. be able to. Even when the left front and rear wheels are slippery due to muddyness, the right front wheel is driven by the prime mover, and the right rear wheel is driven by the left front wheel hydraulic pump and the right rear wheel hydraulic motor. Driven by the prime mover, the wheels do not slip.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. 1 showing an embodiment. Drive wheels 3a and 3b are attached to drive shafts 2a and 2b extending left and right from a main engine 1 of the vehicle, and hydraulic pumps 4a and 4b are attached to the drive wheels 3a and 3b. In this embodiment, the drive wheels 3a and 3b are front wheels, and the rear wheels are driven wheels 6a and 6b. Hydraulic motors 5a and 5b are attached to the driven wheels 6a and 6b. Hydraulic pump 4a and hydraulic motor 5 diagonally opposed to each other
The hydraulic circuit 8a communicates with b, and a flow rate control valve 7a is provided on the forward side of the hydraulic circuit 8a. Similarly, the hydraulic pump 4b and the hydraulic motor 5a are communicated with each other by a hydraulic circuit 8b, and a flow rate control valve 7b is provided on the forward side of the hydraulic circuit 8b. The hydraulic circuits 8a and 8b intersect. The flow control valve 7 is controlled by a signal from the controller 9. The controller 9 is a steering angle sensor 10,
A signal from the vehicle speed sensor 11 is input to set a signal value for determining the number of rotations of the rear wheel 6 and sent to the flow control valve 7.

In the above structure, the hydraulic pumps 4a, 4
Since the front wheels 3a, 3b equipped with b are connected to the rear wheels 6a, 6b equipped with hydraulic motors 5a, 5b by hydraulic circuits 8a, 8b containing incompressible fluid, only one wheel slips. Will never occur. Therefore, the power generated by the hydraulic pumps 4a, 4b rotatably driven by the main motor 1 is controlled by the flow rate control valves 7a, 7b to a value such that the rear wheel rotation speed corresponding to the steering angle and the vehicle speed can be obtained, and the rear wheels 6a. ,
6b is supplied to the hydraulic motors 5a and 5b that rotate and drives the front wheels 3 to which the hydraulic pumps 4a and 4b are mounted.
When both a and 3b try to slip, the rear wheel 6
The hydraulic motors 5a and 5b mounted on a and 6b serve as loads, the driving force of the main motor 1 is supplied to the rear wheels 6a and 6b, the front wheels 3a and 3b do not slip, and the vehicle is a stable 4WD vehicle. Can be held.

If the left end of the road is muddy, the front wheel 3
When a slips, the rear wheel 6b diagonally opposed to the front wheel 3a is driven by the hydraulic motor 5b to which the hydraulic fluid is supplied from the hydraulic pump 4a through the hydraulic circuit 8a. Since the rear wheel 6b does not slip on the road surface, it is possible to escape from the slip state without mounting a limited slip differential or the like.

That is, even if the front wheels 3a, 3b slip, the driving force is not wasted and the two wheels 3b, 6b or the three wheels 3b, 6 are not lost.
It becomes possible to escape from the slip situation of the front wheels 3a and 3b by traveling to b and 6a and to travel. Front wheel 3 in the above embodiment
A and 3b are driven to rotate by the prime mover 1, but the rear wheels 6
a and 6b are rotationally driven by the main engine 1, hydraulic pumps 4a and 4b are attached to the rear wheels 6a and 6b, hydraulic motors 5a and 5b are attached to the front wheels 3a and 3b, and the hydraulic pumps 4a and 4b and the hydraulic motors are attached. 5a and 5b may be communicated with each other by intersecting hydraulic circuits 8a and 8b similar to the present embodiment.

Further, the hydraulic pumps 4a and 4b may not be directly attached to the wheels, but may be attached to a member such as a drive shaft after the differential gear. Similarly, the hydraulic motors 5a and 5b may not be directly attached to the wheels, but may be attached to the sprung body (vehicle body) via a constant velocity ball joint, a drive shaft, or the like.

[0013]

Since the present invention has the above-mentioned structure, it has the following excellent effects. (A) The differential gear and propeller shaft are not required, and even if one or both of the left and right wheels of the main engine drive slip, it can easily escape from the slip. (B) There is no difference in the number of rotation between the front and rear wheels. A stable braking force can be obtained with four wheels when the engine brake is operated with the accelerator off. (C) Since heavy objects such as a differential gear and a propeller shaft are unnecessary, the weight of the vehicle is reduced, and fuel consumption and vehicle dynamic performance are improved.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment.

[Explanation of symbols]

 1 main motor 2a, 2b drive shaft 3a, 3b drive wheel 4a, 4b hydraulic pump 5a, 5b hydraulic motor 6a, 6b driven wheel (other wheel) 8a, 8b hydraulic circuit

Claims (1)

[Claims] 1. A hydraulic pump in which a hydraulic pump is mounted on each of the left and right two wheels of the prime mover or its drive shaft, and a hydraulic motor is mounted on each of the other two left and right wheels or its drive shaft, and which are diagonally opposed to each other. A four-wheel drive vehicle characterized in that the hydraulic circuit and the hydraulic motor are communicated with each other via a hydraulic circuit.