JPS632732A - Torque distribution device in four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To improve stability in straight running and controllability by providing a sensor to detect a handle steering angle whereby not only distributing much more torque for rear wheel driving during handle operations, but also decreasing rear wheel driving force around the neutral point of a handle. CONSTITUTION:An ideal driving force distribution value is obtained from a map 30 set in advance by a torque distribution control device 20 based on a steering angle signal from a handle angle sensor 22. Then, clutch torque to be generated by a hydraulic clutch 11 is computed based on both said value and driving torque detected by an output torque sensor 21. And then, hydraulic pressure corresponding to said clutch torque is applied to the hydraulic clutch 11. This causes rear wheel driving torque around the neutral point of a handle to be decreased, but rear wheel torque to be increased when the handle is steered. Accordingly, the stability of a vehicle during straight running and the controllability during steering can be maintained satisfactorily.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides full-time four-wheel drive 11! In )■
- This relates to a torque distribution control rJIu device during four-wheel drive that arbitrarily controls drive torque distribution to the rear wheels to enable driving with emphasis on maneuverability or stability.

[Conventional technology]

Conventionally, regarding the front/rear wheel drive torque distribution of full-time four-wheel drive vehicles, a hydraulic clutch is installed in the middle of the drive system of the front and one supporting wheel, and the There was one that controlled clutch torque. All of these methods reduce the torque of the rear wheels to counteract the tight corner braking phenomenon M'1j during direct 4WD, or lock the differential for emergency sharpening when equipped with a center differential. [Problems that tTF, 11 attempts to solve] By the way, at present, the vehicle steering characteristics of ordinary automobiles are not affected much by the drive system during normal driving, but when driving in 'tS''a, rain or snow, When driving, there are differences in the behavior of the vehicle depending on whether it is front wheel drive (RWD) or rear wheel drive (RWD).In other words, with front wheel drive, the front tires are affected by the driving force, so the tendency to understeer increases. At the limit, the car drifts.On the other hand, in rear-wheel drive FI cars, the understeer tendency weakens, and at the limit, the car tends to oversteer, often resulting in a spin. Those with a direct connection between the front and rear wheels automatically distribute the driving force mainly according to the axle m ratio during driving, and those with a so-called center differential between the front and rear wheels. 〃The torque distribution is always kept at a constant value of 50:50~7.These four-wheel drive vehicles certainly have vehicle steering characteristics that are different from front-wheel drive and rear-wheel drive. However, since the driving force is not actively distributed during both turns, it has not been possible to significantly change the original vehicle steering characteristics. It is famous for its unique characteristics, and when driving straight, the torque distribution between the front and rear wheels is 50:50, or slightly closer to front wheel drive, giving priority to vehicle stability, and when the steering wheel is turned, it is a four-wheel drive system that leans toward rear wheel drive. (Means for solving the problem) In order to achieve the above object, the torque distribution control of the four-wheel drive vehicle of the present invention is implemented. The gearbox is equipped with a torque distribution device consisting of two pairs of gears and a hydraulic clutch, which bypasses the buffer differential device and transmits the output shaft to the front and rear wheels via a differential differential device. The drive force distribution between the front and rear wheels can be varied by controlling the hydraulic pressure of the 4
An output torque pincer that detects the drive torque of the transmission output shaft, and a steering wheel angle sensor 4 that detects the steering angle of J3 and the steering wheel are installed in the wheel part VJ, and the output torque pin sensor that detects the driving torque of the transmission output shaft is installed.
The yoj~silk portion is set closer to the rear wheel portion 171, and near the neutral point of the steering wheel, the rear wheel drive torque is decreased and the nQ wheel drive torque is increased.

[For production] Based on the configuration described above, the torque distribution control device determines the ideal driving force distribution in from the map set in Y according to the steering angle signal from the steering wheel angle, and detects it using this value and the output torque sensor. The system calculates the clutch torque generated by the hydraulic clutch based on the generated drive torque, applies hydraulic pressure corresponding to this clutch torque to the hydraulic clutch to add it to the rear wheel drive torque, and subtracts it from the front wheel drive torque. It will be closer to rear-wheel drive. 【Example】

Embodiments of the present invention will be described below based on the drawings. 1st
The figure shows the inside of a skeleton showing the transmission system configuration of a four-wheel drive vehicle with a center differential. In the figure, 1 is the engine, 2 is the transmission, 3 is the front wheels, 4 is the rear wheels, 5 is the front differential, and 6 is the In the rear differential, 7 is a center differential composed of a combination of bevel gears A7, 8 is a gear fixed to the output shaft 2a of the transmission 2, and 9 is a gear provided in the differential case of the center differential 7, which meshes with the gear 8. 10 is a torque distribution device, 11 is a torque distribution device'? Bypass II of Iio (hydraulic clutch installed in l110a, 12 is a gear fixed to the front wheel side drive shaft 7a of the center differential 7, 1
3 is a gear fixed to one end of the bypass shaft 10a and meshes with the teeth 102; 14 is a large-diameter IIfli! provided on the drum side of the hydraulic clutch 11; and 15 is a large-diameter gear of the center differential 7. A small diameter gear fixed to the side drive shaft 7b and meshing with the gear 14, 16 a handle, 17 a hydraulic unit,
A predetermined oil pressure Pc is applied to the hydraulic clutch 11. 20 is a torque distribution control device consisting of a microcomputer;
Reference numeral 1 denotes an output i~silk sensor attached to the transmission output shaft 2a, which detects the driving torque T. This is a steering wheel angle sensor that detects the steering angle O of the 22μ steering wheel 16. In addition, in FIG. 2 a3 showing the configuration of the torque distribution control device 20, 30 stores in advance the ideal 1-lux distribution for the steering wheel steering angle θ, that is, the front wheel drive force distribution value Ir1R- in the form of 7 tabs. It is a storage device that has In addition,
This distribution value RF may be determined not in the form of a map but by a predetermined calculation method. Reference numeral 31 denotes a driving force distribution determining means that searches a map using the steering angle θ as an address signal and reads out a front wheel driving force distribution value RF. Reference numeral 32 denotes a crudge hydraulic bell means, which detects L between the read distributed supply [≧F and the driving torque T detected by the output torque sensor 21.
4, calculate the clutch torque TO that should be generated by J3 in the hydraulic clutch 11, and issue a hydraulic command corresponding to this (BII) to the hydraulic unit 17. The device torque T consisting of the transmission 2 is
It is transmitted to the center differential 7 via gear 8 and WJ instep 9,
Here, the driving force T is distributed to ', +0: ', +0, or if the gear ratio is changed, it is distributed to four-wheel drive slightly closer to front wheel drive, for example, 50:50 to 70:30, and is distributed to the front drive shaft 7a. The signal is transmitted to the first wheel killing side drive shaft 1b. Here, if the hydraulic pressure l]C applied to the hydraulic clutch 11 is off at O, for example, in the case of a distribution ratio of 50:50, the front wheels 3 and the rear wheels 4 will each receive a drive torque TF of T/2 and a lower Driven by color. This hydraulic clutch 11 is
The hub 11a has the same diameter gears 12 and 13, and the bypass shaft 10a.
The hydraulic unit 1
When the oil pressure pc is gradually applied from 7, the clutch torque Tc corresponding to the oil pressure pc increases to R1 due to the difference in rotation, and the torque TC is applied to the low speed rotation side drive shaft 11b, which drives the rear wheel side drive shaft 7b. Power TP, is (T/2 + K・C)
On the negative side, the driving force 'rF to the front wheel side drive shaft 7a is (
T/2-Tc), the driving force TF of the front wheels 3 decreases according to the oil 11:PC applied to the hydraulic clutch 11, and the driving force TF of the rear wheels 4 decreases. increases. This torque distribution control requires the small mountain to move straight when the driving concept is to keep the steering wheel 1G near neutral, that is, the steering angle θ detected by the steering wheel angle sensor 22 is within a predetermined value. Therefore, the torque distribution between the front and rear wheels is 50:50, or 50:50, which is slightly closer to front wheel drive.
50-70: As 30, priority is given to the stability of 11 cars. Also, when the steering wheel is turned 1G, that is, when the steering angle θ exceeds a predetermined value, the vehicle is required to make a turning motion. Section #) J (40: 60-20-80) gives priority to vehicle maneuverability. Therefore, the front/rear wheel drive force distribution value R as shown in Fig.
F,nR<tkodashiRF+fl=1), in the storage device 3
It is stored in advance as 0. Then, the torque distribution control 311 device 20 inputs the steering angle O signal from the steering wheel angle sensor 22, and receives the steering angle O signal from the steering angle sensor 22.
Using as an address signal, the driving force distribution determining means 31 searches the driving force distribution value map 30 and finds the front wheel driving force distribution value RF. Now, if the handle 16 is near the neutral point and θ'Fo, the clutch hh pressure calculation means 32
is clutch torque TC/fiO1, that is, oil 11g P
Give a command to the hydraulic unit 17 to set C to 0,
The hydraulic pressure applied to the hydraulic clutch 11 is turned off by O, and the TI
::As a 4-wheel drive for T-Sue 50:50-70:30,
Ensure running stability. - On the other hand, when the steering wheel 16 is turned and the steering angle θ detected by the steering wheel angle sensor 22 deviates from the neutral point and exceeds a predetermined value, the driving force distribution means 3
1 uses the steering angle θ as an address signal to find 1 to'f wheel drive force distribution + 1 TIRF by map search from the storage device 31, and calculates this ll+= and the drive rj of the transmission output shaft 2a detected by the output torque sensor 21.
) + l - rk T, the Crudge music ff performance means 32 calculates RF - (T/2 Tc) / (1'/2
Find the latch torque l-c that satisfies T/2+ and -Tc, and calculate this T
A hydraulic command corresponding to C is given to the hydraulic unit 17, and the corresponding hydraulic pressure pc is sent from the hydraulic unit 17 to the hydraulic clutch 1.
1, four-wheel drive (T, :
Tg = 40:60 to 20:80) to improve the maneuverability (turning ability) of heavy vehicles. Note that the present invention is not limited to the torque distribution device as in Example 1511. Effect of the Invention 1 As described above, according to the present invention, a torque distribution device is provided bypassing the center differential device, and the torque distribution is controlled by the steering angle signal from the steering wheel angle sensor. Wheel drive J: Reduces torque and increases rear wheel drive torque when turning the steering wheel.
As a result, there is no overall torque loss,
This has the effect of improving straight-line stability by 1q during high-speed straight travel, rain or snow, and improving maneuverability (turning performance) by 1:1 when turning.

[Brief explanation of the drawing]

Figure 1 is a skeleton diagram showing the configuration of a four-wheel drive vehicle with a center differential of Honko IJ, Figure 2 is a diagram showing the configuration of the torque distribution control device of the present invention, and a torque distribution diagram of the torque distribution device. Figure 3 is a driving force distribution value map. 2...Transmission, 3...Front wheel, 4...
Contact wheel, 7...center differential, 8.9 is tooth width, 10...
・Torque distribution device, 11...hydraulic clutch, 12-1
5... Gear, 20... Torque distribution control till device, 21... Output torque sensor, 22... Steering wheel angle sensor. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Nobu Kobashi Ukiyo Patent Attorney January Susumu Figure 1, 1 SF52 Figure 3

Claims (1)

[Claims] A four-wheel drive vehicle with variable drive force distribution between the front and rear wheels is equipped with an output torque sensor that detects the drive torque of the transmission output shaft and a steering wheel angle sensor that detects the steering angle of the steering wheel. A torque distribution control device for a four-wheel drive vehicle, characterized in that the distribution is set closer to the rear wheel drive, and the rear wheel drive torque is decreased and the front wheel drive torque is increased near the neutral point of the steering wheel.