JPS62265036A - Braking method and device for vehicle - Google Patents

Abstract

PURPOSE:To shorten the braking distance by applying brakes through changing- over from two-wheel to four-wheel drive at the time of brake application during two-wheel drive. CONSTITUTION:If a brake pedal 9 is stamped during two-wheel drive operation, it is sensed by a sensor switch 29, and a hydraulic clutch 13 is connected through a solenoid valve 26. This causes changing-over into four-wheel drive condition, wherein the power is transmitted to the front wheels 4. Accordingly if the right and left brake pedals 9 are stamped simultaneously to actuate a brake 18, the braking force is applied not only to the rear wheels 5 but also to front 4 to cause stop of rotations of all four wheels. This increases frictional resistance with the surface course of road to lead to shortening of the braking distance till attainment of full stop.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a braking method and device for a vehicle, and relates to a two-wheel drive,
In a vehicle that can be switched to four-wheel drive, when braking is performed while driving in two-wheel drive, the four-wheel drive is switched from two-wheel drive to four-wheel drive and four wheels, front and rear, are braked.

(Prior Art) In a four-wheel drive type agricultural tractor, etc., in which the front and rear wheels are driven, when the circumferential speeds of the front and rear wheels are made equal,
Since the turning radius becomes large when working in fields, etc., the circumferential speed of the front wheels is slightly faster than that of the rear wheels to reduce the turning radius.

However, when the circumferential speeds of the front and rear wheels are changed in this way, there is no problem when the vehicle is running at low speeds, but when the vehicle is running on the road at high speeds, the difference in circumferential speeds causes the front tires to wear out significantly.

Therefore, when driving on the road where a strong driving force is not required, it is common to disconnect the front wheel drive system and drive only the rear wheels, driving the vehicle in two-wheel drive mode.

Therefore, when braking, the brake naturally applies braking force only to the rear wheels.

(Problems to be Solved by the Invention) When braking is applied during rear-wheel drive driving as described above, there is a problem in that it takes a long distance to come to a complete stop.

In other words, when driving at an initial speed of 20km/I+, if sudden braking is applied, it is required to stop within 5m, but with rear-wheel drive, the frictional resistance with the road surface is only on the rear wheels. , the braking distance is around 4.8 to 4.9 m, which is just at the limit of the allowable range.

On the other hand, when the front and rear wheels are in four-wheel drive mode, frictional resistance occurs in all four wheels, so it is possible to come to a complete stop in about 60 to 70% of the braking distance of rear-wheel drive, or about 3 to 3.5 meters. .

(Means for Solving the Problems) In view of such conventional problems, the present invention provides two-wheel drive,
By utilizing the characteristic of being able to switch to four-wheel drive, the braking distance can be shortened even when braking while driving in two-wheel drive, and as a first means of preventing this,
In a vehicle that can switch between 2-wheel drive and 4-wheel drive and is equipped with a brake on the 2-wheel drive side, when braking when driving in 2-wheel drive, the system switches from 2-wheel drive to 4-wheel drive and brakes the 4-wheel drive. As a second means, in a vehicle that is equipped with a clutch in one of the front wheel drive system and a brake in the other of the rear wheel drive system, when the vehicle is running with the clutch in the disengaged state, The present invention includes a detection means for detecting a depression operation of the brake pedal of the brake, and an actuation means for connecting the clutch in response to the detection means.

(Function) When the brake pedal 9 is depressed during two-wheel drive driving, the detection means 29 detects the depression operation of the brake pedal 9.

Then, the actuating means 26 operates and the clutch 25 is connected, so that the two-wheel drive of the front wheels 4 or the rear wheels 5 is switched to four-wheel drive, and the brake 3L 1B applies braking force to the four wheels of the front wheels 4 and the rear wheels 5. do.

(Example) Hereinafter, the present invention will be described in detail with reference to the illustrated example.
The figure illustrates an agricultural tractor that can be switched between two-wheel drive and four-wheel drive. In FIG. 2, reference numeral 1 denotes a tractor body, which includes an engine 2, a transmission case 3, etc., and has front wheels 4 and rear wheels 5. 6 is a steering wheel, 7 is a hood, and 8 is a driver's seat. 9 is a brake pedal, and as is well known, there is a pair of brake pedals on the left and right sides, and they can be connected and disconnected using a connector not shown in the diagram.
By unhooking the connector, the left and right sides can be operated simultaneously or left and right independently. Note that the brake pedal 9 is pivotally supported by a pedal shaft 11 below the step 10.

As shown in FIG. 1, inside the mission case 3, there are provided a transmission 13 which is interlocked with the engine 2 via a clutch 12, a rear wheel differential device 15 which is interlocked with this via a transmission shaft 14, and the like. The rear wheel differential device 15 constitutes a rear wheel drive system 17 together with a pair of left and right rear wheel drive shafts 16, and each of the rear wheel drive shafts 16 is provided with a rear wheel brake 18 for braking the rear wheels 5. It is provided. Each rear wheel brake 18 is linked to the brake pedal 9, and is activated when the brake pedal 9 is depressed.

The transmission shaft 14 is interlocked with a transmission shaft 22 of a front wheel drive system 21 via a gear mechanism 20, and the transmission shaft 22 is connected to the front wheels 4 via a front wheel differential device 23 and a pair of left and right front wheel drive shafts 24.
It is designed to transmit power to. A hydraulic clutch 25 is interposed in the middle of the transmission shaft 22.

The hydraulic clutch 25 is disconnected and connected by a solenoid valve 26, and a solenoid 27 of the solenoid valve 26 is connected to a power source 30 through a parallel circuit of a manual switch 28 and a detection switch 29. .

When the manual switch 2B is turned on, the hydraulic clutch 13 is connected via the solenoid valve 26.

The detection switch 29 is activated when the brake pedal 9 is depressed.
It detects this and turns it on, and is provided on the fixed side so as to make contact with and separate from the brake pedal 9. The detection switch 29 constitutes a detection means, and the electromagnetic valve 26 constitutes an actuation means for connecting the hydraulic clutch 26 in response to the detection means.

In the above configuration, when the manual switch 28 is turned on, the hydraulic clutch 25 is connected via the solenoid valve 26, and the transmission shaft 14 is connected from the engine 2 via the clutch 12 and the transmission 13.
The power transmitted to the rear wheels 5 is transmitted from the rear wheel differential device 15 and the rear wheel drive shaft 16 to the rear wheels 5, and also to the gear mechanism 20.
, hydraulic clutch 25, front wheel differential device 23, front wheel drive shaft 2
4 to the front wheels 4. Therefore, strong driving force can be obtained by four-wheel drive of the front wheels 4 and rear wheels 5.

When driving at high speed on the road with a light load, use the manual switch 28.
is turned off, the hydraulic clutch 13 is disconnected, and the vehicle runs in two-wheel drive that drives only the rear wheels 5.

Therefore, when the brake pedal 9 is depressed for sudden braking, this depression is detected and the detection switch 29 is turned on, and the hydraulic clutch 13 is connected via the solenoid valve 26, so that the front wheel 4
Switches to four-wheel drive mode, which transmits power to the side. Therefore,
When the left and right brake pedals 9 are depressed at the same time to apply braking to the brake 18, the braking force is applied not only to the rear wheel 5 but also to the front wheel 4 side, stopping the rotation of the front wheel 4 and rear wheel 5, so that the road surface This increases the frictional resistance between the vehicle and the vehicle, thereby shortening the braking distance to a complete stop and ensuring a reliable stop. In addition, since the clutch 25 is connected in conjunction with the brake pedal 9,
It is possible to switch to four-wheel braking at the initial stage of braking.

Although FIG. 1 shows an example in which the rear wheels 5 are used as the driving wheels during two-wheel drive, it is also possible to use the front wheels 4 as the driving wheels as shown in FIG. 3. In this case, a front wheel brake 31 is provided on the front wheel drive shaft 24 side, and a hydraulic clutch 25 is provided on the front side of the rear wheel differential device 15.

In the embodiment, the detection switch 29 and the electromagnetic valve 26 are used to connect and disconnect the hydraulic clutch 25, but the present invention is not limited to this. A clutch may be operated.

(Effects of the Invention) According to the method of the present invention, when braking when driving in two-wheel drive, the braking force is applied to the four wheels by switching from two-wheel drive to four-wheel drive, so the frictional resistance with the road surface increases. This shortens the braking distance when stopping suddenly.

In addition, in the device of the present invention, the detection means detects the depression of the brake pedal, and the clutch is connected via the actuating means. Therefore, the clutch can be connected at the beginning of the braking operation, and the time required for four-wheel braking is You can get enough.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a side view of the same tractor, and FIG. 3 is a block diagram showing another embodiment. 1... Tractor body, 4... Front wheel, 5... Rear wheel,
9... Brake pedal, 17... Rear wheel drive system, 18
...Rear wheel brake, 21...Front wheel drive system, 25...
・Hydraulic clutch, 31...Front wheel brake.

Claims (2)

[Claims] (1) In a vehicle that can switch between two-wheel drive and four-wheel drive and is equipped with a brake on the two-wheel drive side, when braking when driving in two-wheel drive, the vehicle switches from two-wheel drive to four-wheel drive. A vehicle braking method characterized by applying braking force to the wheels. (2) In a vehicle equipped with a clutch on one of a front wheel drive system and a brake on the other of a front wheel drive system and a rear wheel drive system, when driving with the clutch in a disengaged state, detecting a depression operation of the brake pedal of the brake. A braking device for a vehicle, comprising: a detection means; and an actuation means for connecting the clutch in response to the detection means.