JP2731923B2 - Torque split type four-wheel drive vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a torque split type four-wheel drive vehicle, and more particularly, to a torque split type four-wheel drive vehicle equipped with an anti-skid braking system.

[Conventional technology]

The most common classification of automobiles, especially passenger cars, is the type in which the engine is mounted on the vehicle and the drive wheels are divided into front and rear wheels. Well-known are the FR type in which the rear wheels are drive wheels, and the FF type in which the engine is mounted and the front wheels are drive wheels.

The former FR type vehicle has excellent turning performance, but has some difficulty in straight running.The latter FF type vehicle has some difficulty in turning performance, but has excellent straight running performance. There are pros and cons.

Therefore, by distributing the engine output torque to the four front and rear wheels, the so-called all wheels, it is possible to use the features of FR and FF vehicles according to the running environment of the vehicle. Proposals for wheel drive vehicles have been made. Japanese Patent Application Laid-Open No. Sho 62-6813 is an example of this type of proposal.
No. 6 can be cited.

[Problems to be solved by the invention]

In a torque split type four-wheel drive vehicle as described above, an anti-skid braking system (hereinafter, referred to as an anti-skid braking system)
When the ABS is installed, there is a problem in that the rear wheel rotation speed is reduced and does not recover during the ABS operation, and the rear wheel lateral force is insufficient to cause spin.

Therefore, by applying a change to the torque transmission force of the hydraulic multi-plate clutch with an ABS operation signal, a restraining force is given between the front and rear wheels to assist recovery when the rear wheel rotation speed decreases, There is a problem that the rotation speeds of the front and rear wheels are the same, and sufficient lateral force cannot be expected for the rear wheels.

Therefore, the present invention provides a torque split type four-wheel drive vehicle equipped with ABS, in which the rear wheel rotational speed is positively recovered even when the ABS is activated, so that the lateral force of the rear wheel can be expected. It is the purpose.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a center differential to which engine output is input, a transmission shaft of a front wheel that transmits power from the center differential to the front wheels, and a part of a transmission torque to the front wheels. It has a hydraulic multi-plate clutch for torque split that transmits to the rear wheels by bypassing the center differential, and a rear wheel transmission shaft that transmits power from the center differential to the rear wheels, for supplying to the hydraulic multi-plate clutch. A torque split type four-wheel drive vehicle comprising: a pump means for generating hydraulic pressure; and a valve means for selectively supplying the hydraulic pressure generated by the pump means to the hydraulic multi-plate clutch, comprising an anti-skid brake system, Gear ratio between the output shaft of the hydraulic multi-plate clutch and the rear wheel transmission shaft, the number of gear teeth of the output shaft of the hydraulic multi-plate clutch is greater than the number of gear teeth of the rear wheel transmission shaft (K ≠ 1) is provided, and the valve means is preferentially actuated by an output signal at the time of operation of the anti-skid brake system to reduce the hydraulic pressure generated by the pump means to the hydraulic multi-plate clutch. And the restraint force between the wheels acts to recover the rear wheel rotation speed.

[Action]

A gear meshing with the rear wheel transmission shaft and the output shaft of the hydraulic multi-plate clutch is provided, and the ratio k between the gear of the rear wheel transmission shaft and the output shaft of the hydraulic multi-plate clutch is set to k> 1. And ABS
The lowering of the rear wheel rotation speed during operation is reduced, and the rear wheel lateral force during turning is generated.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In these figures, reference numeral 1 denotes an engine block, and reference numerals WFL, WFR, WRL, WRR denote front, rear, left and right wheels, and the output of the engine block 1 is formed by a planetary gear 31, a sun gear 32, etc. via a transmission 2. Input to the center differential 3 by the transmission shaft 33,
An output gear 34 constituting the center differential 3 meshes with a gear 61 provided on a transmission shaft 6 to a front wheel differential 5 described later, and a sun gear 32.
A transmission shaft 41 extending from the rear wheel differential 4 extends to the rear wheel differential 4.

A hydraulic multi-plate clutch 7 is provided closer to the rear wheel than the input gear 61 of the front wheel transmission shaft 6, and a gear 72 is attached to a transmission shaft 71 of the hydraulic multi-plate clutch 7. The gear ratio of the gear 42 and the gear 72, that is, the gear ratio k, is 1: 1.08 (k = 1.0).
8).

The hydraulic multi-plate clutch 7 is controlled by the pressure oil supplied from the oil pump 81 to the duty solenoid valve 8 via the output pipe 82 and the return pipe 83.

The output pressure of the duty solenoid valve 8 is controlled by an output signal from a torque split control unit 9, and this output pressure is
Is controlled.

This torque split control unit 9 includes:
Outputs from the accelerator opening sensor 11 of the engine, the engine speed sensor 12, and the position sensor 13 of the select gear of the transmission are input, and the ratio of the torque split is calculated.

The torque split control sensor 9 is configured to receive an output signal in accordance with the operation of the ABS 14 in addition to the signals from the sensors, and when the output signal is input, control for torque split is performed. The operation is canceled once, the output pressure is controlled by controlling the duty solenoid valve 8 in preference to the output signal from each sensor, and the output pressure supplied to the hydraulic multi-plate clutch 7 is appropriately determined. The torque transmission rate of the hydraulic multiple disc clutch 7 is determined appropriately.

Therefore, if the ABS14 operates while the car is running,
A signal corresponding to the operating state is input to the torque split control unit 9, the duty solenoid valve 8 is driven, the output pressure is applied to the hydraulic multi-plate clutch 7, and the transmission torque thereof reaches a certain value (about 1 to 2 kgfm). Further, torque is transmitted from the input gear 61 of the front wheel transmission shaft 6 to the transmission shaft 71, and the gear 72 forcibly drives the gear 42 to distribute the torque to the rear wheels WRL and WRR.

At this time, since the number of teeth n ₇₂ and n _{42 of the} gears ₇₂ and ₄₂ is determined to be n ₇₂ > n ₄₂ , the rear wheel is positively rotated, and moreover, is rotated earlier by the gear ratio k than the front wheel (number %), The lowering of the rear wheel rotation speed is more effectively prevented than in the case of k = 1, and the lateral force of the rear wheel is secured.

That is, when the gear ratio k = 1, as shown by simulation in FIG. 2 (A), when the ABS 14 operates, the rotation speed of the rear wheel WR decreases, and the gear ratio k = It is larger than the case of 1.08, and by setting k> 1, the decrease can be prevented.

〔The invention's effect〕

As is apparent from the above description, in the torque split type four-wheel drive vehicle of the present invention, when the ABS is activated, the torque split control unit is controlled only by the ABS signal in preference to other signals input thereto, and the duty is controlled. The solenoid valve is driven, torque split is performed by the hydraulic multi-plate clutch, the gear provided on the output shaft of the hydraulic multi-plate clutch is meshed with the gear provided on the rear wheel transmission shaft, and the gear ratio of both gears is adjusted. k (> 1) is set so that the rear wheel can be quickly rotated positively during ABS operation. Therefore, it is necessary to secure the lateral force of the rear wheel during turning to prevent the vehicle from falling into a spin state. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a torque split type four-wheel drive vehicle of the present invention, and FIG. 2 is a simulation diagram showing a relationship between a gear ratio and a rear wheel speed. 1 ... engine block 2 ... transmission 3 ... center differential, 31 ... planetary gear, 32 ... sun gear, 33 ... transmission shaft, 34 ... output gear 4 ... rear wheel differential, 42 ... gear 5 ... ... front wheel differential 6 ... front wheel transmission shaft, 61 ... input gear 7 ... hydraulic multi-plate clutch, 71 ... transmission shaft, 72 ... gear 8 ... duty solenoid valve, 81 ... oil pump 9 ... torque split Control unit 11: Accelerator opening sensor 12: Engine speed sensor 13: Position sensor 14: ABS

Claims (1)

(57) [Claims] A center differential to which an engine output is input, a transmission shaft of a front wheel for transmitting power from the center differential to the front wheels, and a part of torque transmitted to the front wheels transmitted to the rear wheels by bypassing the center differential. Pump means for generating a hydraulic pressure for supplying to the hydraulic multi-plate clutch, comprising a hydraulic multi-plate clutch for torque splitting, and a rear wheel transmission shaft for transmitting power from a center differential to a rear wheel; A torque split type four-wheel drive vehicle including valve means for selectively supplying hydraulic pressure generated by a pump means to the hydraulic multiple disc clutch, comprising: an anti-skid brake and a system;
The gear ratio k (k ≠ 1) between the output shaft of the hydraulic multi-plate clutch and the rear wheel transmission shaft is such that the number of gear teeth of the output shaft of the hydraulic multi-plate clutch is greater than the number of gear teeth of the rear wheel transmission shaft. A pair of gears are provided, and the output means at the time of operation of the anti-skid brake system activates the valve means preferentially to supply the hydraulic pressure generated by the pump means to the hydraulic multi-plate clutch, thereby providing a hydraulic pressure between the front and rear wheels. A torque split type four-wheel drive vehicle characterized by applying a restraining force to recover the rear wheel rotational speed.