JPH0425410Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a four-wheel antilock braking system for a part-time four-wheel drive vehicle, which is capable of switching between two-wheel drive and four-wheel drive.

Prior Art One of the front and rear wheels, for example, the front wheels, is directly driven by a transmission, and the other, for example, the rear wheels, is driven from the transmission via a transfer clutch, and four-wheel drive is achieved by controlling the engagement and disengagement of the transfer clutch. In a part-time 4-wheel drive vehicle that can switch between 2-wheel drive and 2-wheel drive, when a braking operation is performed while driving in 2-wheel drive, the activation signal of the brake switch that detects and operates the braking operation is activated. Therefore, a device that automatically switches to four-wheel drive using the transfer clutch and brakes all four wheels, front, rear, left, and right, has already been developed and is disclosed in Japanese Patent Application Laid-Open No. 1983-
It is published as Publication No. 66022.

Problem to be Solved by the Invention However, when the transfer clutch is connected during braking operation and the front and rear wheels are directly connected to create a four-wheel drive state as in the conventional device described above, there is a differential device between the left and right axle shafts for both the front and rear wheels. As a result, only one of the front and rear wheels, either the left or right, may be braked and locked. Therefore, in order to prevent the wheels from locking up during braking, rotation sensors that detect the rotation of the wheels are installed on each of the front, rear, left, and right wheels, and the braking hydraulic system is controlled based on the signals from the multiple rotation sensors. The problem is that it requires many parts and is expensive.

Means for Solving the Problems The present invention has been developed in the past in differential devices. For example, when one of the left or right wheels lifts off the road surface and spins when driving on a rough road such as a gravel road or uneven road, the other wheel In order to eliminate the inconvenience of losing driving force, a deflock mechanism is provided that allows the left and right axle shafts to be directly connected by the driver's operation, and there is also a conventional overspeed warning system. For example, we focused on the fact that a vehicle speed sensor is provided to detect the vehicle speed from the number of rotations of a rotating body that rotates in conjunction with the ring gear or drive pinion of a final reduction gear, or one of the left and right wheels. In conjunction with the operation, the transfer clutch is engaged and one of the front and rear deflock mechanisms is locked, and the wheel deceleration is determined from the signal of the vehicle speed sensor, and when the wheel deceleration exceeds a predetermined value. A control circuit is provided which occasionally issues a brake lock signal, and the brake hydraulic pressure control device is controlled by the brake lock signal.

Function The present invention uses the above-mentioned configuration to prevent brake lock by detecting brake lock of all wheels using only one vehicle speed sensor for detecting vehicle speed and controlling the brake fluid pressure. It's something you get.

Embodiments The details of the present invention will be explained below with reference to embodiments shown in the accompanying drawings.

In Fig. 1, 1 is a power unit consisting of an engine, a transmission, etc., and 3
Left and right axel shafts 2 that drive a and 3b
a, 2b are configured to be directly driven by the power unit 1, and a propeller shaft 5 is connected to the output shaft of the power unit 1 via a transfer clutch 4.
If they are in contact with each other, the driving force of the power unit 1 is transmitted to the rear axle shafts 7a, 7b via the propeller shaft 5 and the rear differential device 6, which rotates the left and right rear wheels 8a, 8b. When the transfer clutch 4 is disengaged, power transmission to the rear wheels 8a and 8b is cut off, and the state is switched to a two-wheel drive state in which only the front wheels 3a and 3b are driven. ing.

The rear differential device 6 is provided with a differential lock mechanism 6' to prevent the driving force of the other wheel from being lost when one of the left and right wheels lifts off the road surface and spins while driving on a rough road. ing.

9 is a brake pedal, and 10 is a master cylinder. When the brake pedal 9 is depressed, the master cylinder 10 operates, and two systems of brake hydraulic pressure piping 11 are activated.
Braking fluid is force-fed to each wheel cylinder of front wheels 3a, 3b and rear wheels 8a, 8b by a, 11b, so that all wheels are braked.

Reference numeral 12 denotes a vehicle speed sensor that detects the vehicle speed from the rotational speed of a rotating body that rotates in conjunction with, for example, a ring gear or a drive pinion of a final reduction gear, or one of the left and right wheels. It is generally equipped as

In the braking system for a part-time four-wheel drive vehicle as described above, in the present invention, in conjunction with the braking operation, the transfer clutch 4 is connected to bring the front and rear wheels into a four-wheel drive state, and the differential lock mechanism 6' is locked. The control circuit 13 calculates the wheel deceleration from the output signal a of the vehicle speed sensor 12, and when the wheel deceleration exceeds a predetermined value, issues a brake lock signal b, and uses the brake lock signal b to activate the brake. A brake hydraulic pressure control device 14 provided in the middle of the hydraulic pressure piping 11a, 11b is operated to control the brake hydraulic pressure and prevent the brake from locking.

The wheel braking lock mode when the transfer clutch is simply engaged without locking the differential lock mechanism 6' of the rear differential device 6 and a four-wheel drive state in which the front and rear wheels are directly connected is shown in Figure 2 (the locked wheels are marked with diagonal lines). As shown in Fig. 3), when all four wheels are locked, (a), when the left front wheel 3a and the right rear wheel 8b are locked, (b), when the right front wheel 3
There are five types: (c) when b and the left rear wheel 8a lock, (d) when the left front and rear wheels 3a and 8a lock, and (h) when the right front and rear wheels 3b and 8b lock. As described above, in order to detect the brake lock mode, rotation sensors must be provided on all four wheels, front, rear, left, and right, to detect their respective rotations.

The front and rear wheels are directly connected to each other in four-wheel drive mode, and the differential lock mechanism 6' of the rear differential device 6 is activated to lock the left and right rear axle shafts 7a and 7.
If the rear axle shafts 7a and 7b are directly connected, when one of the left and right rear wheels is locked as shown in FIG. Further, when both the left and right rear wheels are locked, the output shaft of the power unit 1 is also locked via the propeller shaft 5 and the transfer clutch 4, and the left and right front wheels 3a connected to the output shaft of the power unit 1 are locked. , 3b are both in the locked state, so there can be no other lock mode than the four-wheel lock shown in FIG. 2A.

Therefore, if the configuration is such that the transfer clutch is engaged in conjunction with the braking operation and the deflock mechanism is locked, the change in wheel deceleration obtained from the signal of one vehicle speed sensor 12, which is conventionally generally equipped, can be applied. The four-wheel lock state can be reliably detected, and the brake fluid pressure control device 14 can be operated to perform four-wheel anti-lock.

Defrot lock mechanism 6' and brake fluid pressure control device 1
4 can be of any conventionally known structure that is widely used, and the defrock mechanism 6' and the brake fluid pressure control device 14 can be
As the actuator for actuating, any type of actuator may be adopted, such as a diaphragm device using negative pressure sucked into the engine or an electromagnetic solenoid device actuated by energization.

Fig. 1 shows an example in which the present invention is applied to a part-time four-wheel drive vehicle in which only the front wheels are driven when two wheels are driven, but the rear wheels are the driving wheels when two wheels are driven. Needless to say, the present invention can also be applied to part-time four-wheel drive vehicles.

Effects of the invention As described above, according to the invention, the part-time 4 differential device is equipped with a deflock mechanism.
In a wheel drive vehicle, a transfer clutch is brought into contact in conjunction with a braking operation to lock either the front or rear deflock mechanism, and the rotating body is conventionally provided in a vehicle and rotates in conjunction with wheel rotation. The wheel deceleration is obtained from the output signal of one vehicle speed sensor that detects the vehicle speed from the rotational speed of the vehicle, and when the wheel deceleration exceeds a predetermined value, a brake lock signal is obtained, and the brake lock signal activates anti-lock during braking. It allows for accurate operation, facilitates control, reduces the number of parts, and significantly reduces costs. Combined with good functionality, it has great practical effects. It is possible to bring about

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a power transmission system and a brake control system showing an embodiment of the present invention;
D and E are explanatory plan views respectively showing the manner in which the wheels are locked during braking in a four-wheel drive state in which the front and rear wheels are directly connected. 1...Power unit, 2a, 2b...Front axle shaft, 3a, 3b...Front wheel, 4
... Transfer clutch, 5 ... Propeller shaft, 6 ... Rear differential device, 7
a, 7b...Rear axle shaft, 8a, 8b
... Rear wheel, 9 ... Brake pedal, 10 ... Master cylinder, 11a, 11b ... Brake hydraulic pressure piping, 12 ... Vehicle speed sensor, 14 ... Brake hydraulic pressure control device.

Claims (1)

[Scope of utility model registration request] A transfer clutch is provided in one of the drive power transmission systems for the front wheels and the rear wheels, and by controlling the engagement and disengagement of the transfer clutch, the front and rear wheels can be directly coupled to 4-wheel drive and 2-wheel drive. In addition, in a part-time four-wheel drive vehicle equipped with a differential lock mechanism in the differential device, the transfer clutch is engaged in conjunction with the braking operation to lock either the front or rear differential lock mechanism. The wheel deceleration is determined from the signal of one vehicle speed sensor that detects the vehicle speed from the number of rotations of a rotating body linked to the wheel rotation, and a brake lock signal is issued when the wheel deceleration exceeds a predetermined value. A brake fluid pressure control device is installed in the brake fluid pressure piping system between the master cylinder and the front and rear four wheels. A four-wheel antilock braking device for a part-time four-wheel drive vehicle, characterized by the following: