JPS6111097Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a brake device for a traveling work vehicle or the like that travels on rough terrain or in fields.

Vehicles moving on rough terrain or in fields cannot be sufficiently steered by simply changing the angle of the steered wheels using the steering wheel; instead, the brakes are applied to one side of the drive wheels and the rotation of the other wheel is increased using a differential device. The vehicle is then steered.

In the past, there were many small-sized steering vehicles, so the brakes were activated by moving a link using the driver's foot pedal force, but in large vehicles, the brakes could not be applied completely with pedal force alone. First, a hydraulic cylinder is used to amplify the acting force. Conventionally, in this hydraulic brake, a master cylinder was provided for each left and right brake, and the rotation of the left and right brake pedals pushed each master cylinder, but when driving on the road,
When the brakes were to be applied to both the left and right wheels at the same time, the slight difference in pressure between the left and right master cylinders caused the brakes to work on one side, causing the vehicle to tilt at high speeds, leading to a serious accident.

This invention uses a single master cylinder for the left and right brake pedals, and uses a hydraulic directional control valve to switch the oil path to guide pressure oil to the left and right brake cylinders, thereby performing unilateral braking. .

The purpose of the present invention is as described above, and the structure of the present invention will be explained based on the structure of the embodiment shown in the attached drawings.

FIG. 1 is an overall side view of the agricultural tractor.

An engine 2 is housed within a bonnet 1, and front wheels 4 and the like are supported by a front frame 3 that projects forward from a lower side surface of the engine 2.

A clutch housing 5 is fixed to the rear surface of the engine 2, a transmission case 7 is fixed to the rear surface of the clutch housing 5, and a rear axle case 8 is further fixed to the rear surface of the transmission case 7. Rear axle housing 1 on both sides of the rear axle case
1 is attached, and the axle 16 of the rear wheel 12 is supported by the rear axle housing 11.

Further, a disc brake device is installed inside the rear axle housing 11, and braking is performed by pushing the plate of the disc brake with a piston in a brake cylinder.

FIG. 2 is a sectional view showing the deceleration and braking device inside the rear axle housing 11.

Differential shaft 13 protruding from the differential device
Three planetary gears 14 mesh with a gear 13a provided at the tip of the planetary gear 13, and the three planetary gears 14 mesh with a fixed inner gear 22, and the rotation of the gear 13a is reduced by the planetary gear fixed body 15. It is expressed as the number of rotations. The planetary gear fixed body 15 is the axle 1
6 and is spline-fitted to rotate the rear wheel 12. The friction plate 17 of the disc brake is the differential shaft 1
3, and is held between the side surface of the rear axle housing 8 and the plate 18 to exert a braking force.

A portion of the plate 18 protrudes and serves as a brake piston 18a, which moves laterally within a brake cylinder 11a carved in the rear axle housing. Pressure oil is supplied to the brake cylinder 11a through a pipe to the joint 19.

Figure 3 is the hydraulic circuit diagram of this invention. Figure 4 is a diagram showing the position to press the brake pedal. Figure 5 is the front view of Figure 4. Figure 6 is a plan view of Figure 4. FIG. 7 is a drawing showing an electric circuit.

There are two brake pedals 6, a left 6a and a right 6b, each having a protrusion 6c at its base that pushes a master piston 9a of a master cylinder 9. The tip of the master piston is provided with a contact part 6b that can come into contact with the two protrusions 6c, so that the master piston 9 is provided with a contact part 6b that can come into contact with the two protrusions 6c.
a is pressed and pressure oil is sent to the hydraulic directional control valve 10. The hydraulic directional control valve 10 has left and right solenoids 2.
1a, 21b, and the excitation of the solenoids 21a, 21b is caused by the left and right brake pedals 6.
This is done by push button switches 20a and 20b protruding from the center of the switches a and 6b. When the driver brakes either the left or right brake, before the brake pedals 6a, 6b start operating, the driver depresses the pushbutton switches 20a, 20b built into the pedal. , the hydraulic directional control valve 10 is switched via the solenoids 21a and 21b.

When the pedal is then depressed, pressure oil is sent out from the master cylinder 9 and braking is performed.
If you want to brake both at the same time, press the center part of the brake pedal.Since neither pushbutton switch is touched, the hydraulic directional control valve is in the center position, and both brake cylinders 11a, 11
Since pressure oil is supplied to a at the same time, both the left and right brakes start braking.

However, when you want to brake both, it is possible that your foot accidentally touches the push-button switch, so to eliminate this risk, you can turn off the one-way switch 25.

As described above, the present invention provides brake cylinders 11a for the left and right rear wheels 12, 12 of an agricultural tractor.
11a, and left and right brake pedals 6a, 6b.
By depressing the brake cylinder 11a,
In the configuration in which pressure oil is sent to 11a to perform braking,
By depressing either or both of the left and right brake pedals 6a, 6b, the master cylinder 9
The push button switches 20a and 20b, which turn ON and OFF the switching solenoids 21a and 21b of the hydraulic directional control valve 10, which is configured to push the master piston 9a of the master piston 9a, and which switches the pressure oil of the master piston 9a to the left and right or both, The distance between the push button switches 20a and 20b of the left and right brake pedals 6a and 6b, which protrude from the pedal surfaces of the brake pedals 6a and 6b and are arranged close to each other, can be placed on the pedals without the operator's foot touching both switches. Since the spacing is set at a certain interval, the following effects can be achieved.

First, push button switches 20a, 20b protrude from the pedal surfaces of the brake pedals 6a, 6b.
Since the hydraulic directional control valve 10 is switched before the pedal is depressed, there is no need for the hydraulic directional control valve to switch after the brake pedal has been depressed considerably as in the conventional patent publication No. 51-35977. This eliminates the problem of pressure oil pushed in by the master piston temporarily losing its place and becoming trapped.

Furthermore, since the hydraulic directional control valve 10 is switched all at once by a combination of a switch and a solenoid, it is similar to a conventional rotary valve linked to a pedal. This solves the problem that the amount of oil is limited by the position of the rotary valve depending on how much the pedal is pressed, making it difficult to brake.

Second, the push button switches 20a, 20 of the left and right brake pedals 6a, 6b arranged close to each other
The distance b is such that the operator's foot can be placed on the pedal without touching both switches, so even if the operator's foot slips or makes a mistake, it is possible to press both switches at once. Moreover, when driving at high speeds, by depressing only one switch, it is possible to prevent rollover accidents caused by one-sided braking at high speeds.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of the agricultural tractor, Fig. 2 is a sectional side view of the rear axle housing, Fig. 3 is a hydraulic circuit diagram of the present invention, Fig. 4 is a drawing showing the position where the brake pedal is depressed, Fig. 5 4 is a front view of FIG. 4, FIG. 6 is a plan view of FIG. 4, and FIG. 7 is a drawing showing an electric circuit. 6... Brake pedal, 9... Master cylinder, 10... Hydraulic directional control valve, 11... Rear axle housing, 20... Push button switch,
21...Solenoid.

Claims (1)

[Scope of utility model registration request] In a configuration in which brake cylinders 11a, 11a are provided on the left and right rear wheels 12, 12 of an agricultural tractor, and pressure oil is supplied to the brake cylinders 11a, 11a to perform braking by depressing the left and right brake pedals 6a, 6b. brake pedal 6
By depressing one or both of a and 6b, the master piston 9 of the master cylinder 9
The switching solenoids 21a and 21b of the hydraulic directional control valve 10 configured to push the master piston 9a to the left or right or both directions are configured to press the
Push button switch 20a, 2 to turn on and off
0b protrudes from the pedal surfaces of the left and right brake pedals 6a, 6b, and the push button switches 20a,
20b is such that an operator's foot can be placed on the pedal without touching both switches.