JPS6255227A - Control device for torque distribution in four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To obtain a driving torque responsive to a load so as to improve fuel consumption by providing a control device for controlling a torque distribution varing means, in order to change the distribution of a driving torque to a front wheel and a rear wheel through the signal from a load detecting means. CONSTITUTION:A driving wheel 33 is supported inside a transfer case 31 and, on the outer periphery of the driving wheel end side, a front wheel driving clutch 34 and a rear wheel driving clutch 35 are provided. And hydraulic operating oil chambers 34b, 35b of the clutchs 34, 35 are intercommunicated with an oil pump 45 through variable flow control valves 43, 44, which are operatingly controlled by a control unit 47. A detected signal, which is supplied from a load detecting means 48 for detecting a load applied on the front wheel and the rear wheel and a torque sensor 49 for detecting driving torque on the basis of the revolving speed of a transmission output shaft 21, is input to the control unit 47, thereby it is possible to obtain the driving torque responsive to the load.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) -1 The present invention relates to a torque distribution control device for a four-wheel drive vehicle that drives front wheels and rear wheels.

(Prior Art) Conventionally, as a torque distribution control device for this type of four-wheel drive vehicle, for example, as disclosed in Japanese Patent Laid-Open No. 58-56920, a transfer clutch for switching between two-wheel drive and four-wheel drive is used. A known vehicle is one in which the distribution of drive torque to the front and rear wheels is changed in three stages during four-wheel drive.

In addition, from the standpoint of further improving acceleration performance and braking efficiency, the present applicant has developed a torque distribution control system for four-wheel drive vehicles that controls the distribution of drive torque to the front and rear wheels based on the engine torque and the steering wheel. They have proposed a system that can continuously and steplessly change the degree of angle, acceleration, etc. depending on the driving condition as elements (see Japanese Patent Application No. 59-276731).

That is, the proposed torque distribution control device includes a front wheel drive hydraulic clutch that connects the front wheel drive shaft and the output shaft of the transmission, and a rear wheel drive hydraulic clutch that connects the rear wheel drive shaft and the output shaft of the transmission. The vehicle is configured to include a clutch and a control means for variably controlling the pressure of hydraulic oil to both clutches according to the driving condition.

(Problems to be Solved by the Invention) By the way, when the load acting on the front wheels and rear wheels of a vehicle is unevenly distributed in the front-rear direction,
This is particularly true when starting off or driving on a slope; in such cases, transmitting a correspondingly large drive torque to the wheel on the side on which a large load is applied improves steering stability and This is desirable in terms of fuel efficiency, and specific measures are required.

The present invention has been made in view of the above, and its purpose is to distribute the driving torque to the front and rear wheels depending on the load state acting on the front and rear wheels, independent of the driving state. The purpose is to change the steering speed accordingly, thereby improving steering stability and fuel efficiency.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is provided in the output shaft of the transmission, and provides variable torque distribution between the 1 and 2 torque distributions for the front and rear wheels. variable means; load detection means for detecting loads acting on the front wheels and the rear wheels, respectively;
The vehicle is configured to include a control means for controlling the torque distribution variable means so as to change the distribution of drive torque to the front and rear wheels based on the signal from the load detection means.

(Function) In the above configuration, in the present invention, the load state acting on the front wheels and the rear wheels is detected by the load detection means, and the torque distribution variable means is controlled by the control means based on the signal of the load detection means. By variably controlling the distribution of drive torque to the front and rear wheels, drive torque can be obtained at the front and rear wheels according to their load conditions.

Here, the torque distribution variable means is a front wheel drive hydraulic clutch that connects the front wheel drive shaft and the output shaft of the transmission, and a rear wheel drive hydraulic clutch that connects the rear wheel drive shaft and the output shaft of the transmission. In this case, the distribution of drive torque to the front and rear wheels is continuously, steplessly and reliably changed according to the load condition of the front and rear wheels by controlling the pressure of hydraulic oil to both of the clutches. I can do it.

(Example) Embodiments of the present invention will be described below based on the drawings.

1 to 3 show one embodiment of the present invention. Figure 2 shows the drive power transmission system of a four-wheel drive vehicle, in which 1 is the engine, 2 is the transmission connected to the engine 1, and 3 is the torque distribution control connected to the transmission 2. This is a transfer device, in which the output torque of the engine 1 is shifted by the transmission 2 and then distributed to a predetermined ratio by the transfer 3, and the driving torque after this distribution is transmitted via the propeller shaft 6 or 7, respectively. The power is then transmitted to the front wheels 8 and rear wheels 9.

FIG. 3 shows the configuration of the transfer 3. As shown in FIG. As shown in the figure, a drive shaft 33 is rotatably supported within the transfer case 31 via a bearing 32, and one end of the drive shaft 33 is connected on the same axis as the output shaft 21 of the 1-transmission 2. A clutch 34 for driving the front wheels and a clutch 35 for driving the rear wheels are provided on the outer periphery of the other end of the drive shaft 33. The other end of the drive shaft 33 is connected via the rear wheel drive clutch 35 to a driven shaft 36 disposed on the same axis as the drive shaft 33.
The driven shaft 36 is connected to a propeller shaft 7 which is a rear wheel drive shaft. Further, the clutch hub 34a of the front wheel drive clutch 34 is integrally formed with an output gear 37 rotatably attached to the outer periphery of the drive shaft 33. The output gear 37 meshes with a transmission gear 39 fixed to an intermediate shaft 38 disposed parallel to the drive shaft 33, and the transmission gear 39 is parallel to the drive shaft 33 and the intermediate shaft 38. A driven shaft 40 disposed at the front wheel meshes with an integrally molded gear 41, and the driven shaft 40 is connected to a propeller shaft 6, which is a front wheel drive shaft, via a conniversal joint 42.

The front wheel drive and rear wheel drive clutches 34 and 35 are both hydraulically operated wet friction clutches, and their operating hydraulic chambers 34 and 35 are hydraulically operated wet friction clutches. When hydraulic oil is supplied to pistons 34c and 35b, the oil pressure causes pistons 34c and 3
5c is activated to tighten the plurality of friction plates 34d and 35d, and the frictional force generated thereby transmits the drive torque of the drive shaft 33 to the front wheels and the rear wheels, respectively. It is configured. The torque transmitted by each of the clutches 34 and 35 is transmitted to its operating hydraulic chamber 34b.

It changes depending on the pressure of hydraulic oil applied to 35b.

FIG. 1 shows a hydraulic control system that controls the pressure of hydraulic oil applied to both clutches 34, 35. As shown in the figure, the working hydraulic chambers 34b of both clutches 34, 35,
35b is connected to an oil pump 45 via a variable flow control valve 43 or 44, respectively.
is designed to suck up the oil in the oil tank 46 and discharge it at a predetermined pressure. The operation of the flow rate control valve 43.4=1 is controlled by a control unit 47 as a control means, and the control unit 1-47 is loaded with loads for detecting the side effects acting on the front wheels and the rear wheels. Detection means 48
A detection signal from a sensor 49 is inputted as a torque for detecting the driving torque from the rotational speed of the output shaft 21 of the 1-heran transmission.

Next, we will discuss the operation of the above embodiment, particularly the front wheel drive clutch 3.
To explain the operation of the hydraulic control system that controls the pressure of the hydraulic oil applied to the front wheels 8 and the rear wheel drive clutch 35, the control unit 47 detects the loads acting on the front wheels 8 and the rear wheels 9, respectively. Upon receiving the detection signal from the means 48, for example, if the load acting on the front wheel 8 is greater than the load acting on the rear wheel 9, one of the two flow control valves 43, 44 is activated. The flow rate control valve 43 that communicates with the front wheel drive clutch 34 is heard louder, and high pressure hydraulic oil is applied to the front wheel drive clutch 34, increasing the torque transmitted by the clutch 34. On the other hand, hydraulic oil with a pressure lower than that applied to the front wheel drive clutch 34 is applied to the rear wheel drive clutch 34, and the transmission 1-
Luk becomes smaller.

In this way, based on the detection signal from the load detection means 48, the front wheel drive clutch 34, the rear wheel drive clutch 34, 35
(Since the distribution of drive torque to the wheels is variably controlled, the front wheels 8 and rear wheels 9 can obtain drive torque according to their load conditions, improving steering stability. In addition, fuel consumption can be reduced by effectively utilizing the driving torque.

Furthermore, in the above embodiment, the front wheel drive clutch 34 and the rear wheel drive clutch 35 constitute a torque distribution variable means for varying the distribution of the drive torque to the front and rear wheels, and By controlling the pressure of the hydraulic fluid, the distribution of drive torque can be changed continuously, steplessly, and reliably, making it possible to more effectively improve steering stability and fuel efficiency.

In the above embodiment, the distribution of drive torque to the front and rear wheels was configured to be changed according to the load condition acting on the front and rear wheels. Of course, it may be changed in accordance with the driving condition, which is based on factors such as the initial steering angle and the degree of acceleration.

(Effects of the Invention) As described above, according to the torque distribution control device for a four-wheel drive vehicle of the present invention, the load state acting on the front and rear wheels is detected by the load detection means; Based on the signal (-), the distribution of driving torque to the front and rear wheels is variably controlled by the variable torque distribution means, so that the front wheels and rear wheels can obtain driving torque according to their load conditions.
Steering stability and fuel efficiency can be improved.

Particularly, the torque distribution variable means includes a front wheel drive hydraulic clutch that connects the front wheel drive shaft and the output shaft of the transmission, and a rear wheel drive hydraulic clutch that connects the rear wheel drive shaft and the output shaft of the transmission. When configured with a clutch, the distribution of drive torque to the front and rear wheels can be continuously and reliably changed according to the load condition of the front and rear wheels by controlling the pressure of hydraulic oil to both of the clutches. Therefore, it is possible to further improve steering stability and the like.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Fig. 1 is a configuration diagram 71' showing a hydraulic control system, Fig. 2 is a schematic diagram showing a driving force transmission system of a four-wheel drive vehicle, and Fig. 3 is a diagram showing a transfer system. FIG. 3 is a sectional view showing the configuration. 2...Transmission, 3...Transfer, 6.7...Propeller shaft V-foot, 21...Output shaft,
34... Front wheel drive clutch, 35... Rear wheel drive clutch, 43.44... Flow rate control valve, 47... Control unit, 48... Load detection means.

Claims (2)

[Claims] (1) A variable torque distribution means that is provided on the output shaft of the transmission and that varies the distribution of drive torque to the front and rear wheels, a load detection means that detects the loads acting on the front wheels and the rear wheels, and the load A torque distribution control device for a four-wheel drive vehicle, comprising: control means for controlling the torque distribution variable means to change the distribution of drive torque to the front and rear wheels in response to a signal from the detection means. (2) The variable torque distribution means includes a front wheel drive hydraulic clutch that connects the front wheel drive shaft and the output shaft of the transmission, and a rear wheel drive hydraulic clutch that connects the rear wheel drive shaft and the output shaft of the transmission. A torque distribution control device for a four-wheel drive vehicle according to claim (1).