JPH0522611B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hydraulic disc brake device for a wheel-type vehicle, for example, a four-wheel drive vehicle such as an agricultural tractor or an earth-carrying vehicle.

(b) Prior Art The technology related to hydraulic disc brake devices has been known to the public. For example, Jitsukaiaki
This is similar to the technique described in Japanese Patent No. 58-74633.

(C) Problems to be Solved by the Invention The present invention provides that when the left and right hydraulic disc brake devices are braked at the same time, the front wheels are driven as they are without being cut off, but only one of the hydraulic disc brake devices is braked. When braking and using it as a steering brake, front wheel drive is automatically turned off even in four-wheel drive mode.

(d) Means for Solving the Problems The problems to be solved by the present invention are as described above, and next, the means for solving the problems will be explained.

When the left and right brake pedals 2L and 2R are operated simultaneously and the left and right hydraulic disc brake devices are simultaneously braked and used as travel brakes, the same pressure oil is discharged from the left and right pistons 3L and 3R and reaches the hydraulic cylinders 14 and 14. An equalizer device E is provided to equalize the pressure, and after passing through the equalizer device E, bypasses 25L and 25R are configured to introduce the pressure oil sent to the hydraulic cylinders 14 and 14 to the left and right sides of the front wheel drive cutoff valve 26. When only one of the brake pedals 2L and 2R is braked, pressure oil from one of the bypasses 25L and 25R flows in, causing the left and right oil chambers of the front wheel drive cutoff valve 26 to become unbalanced, causing the spool to slide, and reducing the front wheel drive hydraulic pressure. The bypass 26a provided in the front wheel drive cutoff valve 26 is configured to open the bypass 26a provided in the front wheel drive cutoff valve 26 in order to send pressure oil between the clutch 21 and the front wheel drive clutch brake valve 22 to the drain circuit.

(E) Embodiments The objects of the present invention are as described above, and next, the specific 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 an agricultural tractor, FIG. 2 is a cross-sectional view taken along line mm in FIG. 4, and FIG. 3 is a cross-sectional view taken along line nn in FIG. 4 is a side view, and FIG. 5 is a hydraulic circuit diagram of the disc brake device of the present invention.
In Figure 1, the agricultural tractor has front wheels 28,
28, a vehicle capable of four-wheel drive with rear wheels 1 and 1 is shown. 29 is a front wheel power transmission shaft device. 30
is a clutch pedal, and left and right brake pedals 2L and 2R for running and steering are arranged side by side at positions opposite to this clutch pedal. When the vehicle is used as a traveling brake device to brake both wheels while driving on the road, the left and right brake pedals 2L and 2R are used in a connected manner.

In Fig. 5, the left and right brake pedals 2L,
When one or both of 2R are depressed, hydraulic oil tank 2
The hydraulic oil sucked from 0 and 20 is transferred to the pistons 3L and 3.
Push out with R. Then, the hydraulic brake discs 5L and 5R, which are composed of the hydraulic cylinder 14 and the actuator 7, are pressed to perform a hydraulic brake operation.

In FIG. 5, C is a gear sliding type transmission device of an agricultural tractor, and B is a differential gear device.

In the present invention, the actuator 7 of such a hydraulic disc brake device can be rotated in the circumferential direction by rotation of the parking brake lever 6, and this rotation causes the actuator 7 to move in the cam groove 7a carved in the actuator 7. The actuator 7 is pressed against the brake disc 5 side by pushing out the ball 8 from the inner wall of the hydraulic cylinder 14, so that braking can also be applied by such mechanical operation. It is.

This will be explained in more detail with reference to FIGS. 2, 3, and 4. 12 is a brake shaft that meshes with the differential side gear of the differential gear device. A final gear device is installed on this brake shaft to rotate the axle and rotate the rear wheels 1L and 1R.

A brake disc 5 is engaged on this brake shaft 12 and rotates. The brake shaft is braked by pressing and braking this brake disc with the actuator 7. 16 is a rear axle case of an agricultural tractor, and a brake disc 5 and an actuator 7 are fitted between a bearing body 16a fixed to the rear axle case and a hydraulic cylinder 14 so as to be movable left and right.

The hydraulic cylinder 14 is a part of the rear axle housing as a whole.

Pressure oil sent from the pistons 3L and 3R is forced into the pressure oil injection hole 14a of the hydraulic cylinder 14.

This pushes the actuator 7 to the left, compressing the brake disc 5 between it and the outer surface of the bearing body to perform braking.

Conventionally, this was the only configuration, but in the present invention, this is further developed, and a ball 8 as shown in FIG. The cam groove is arranged in an eye shape as shown in 7a of FIG. When used as a hydraulic disc brake device, the servo spring 9 shown in FIG. 4 urges the ball 8 in the most stable direction, so the ball 8 fits into the deepest part of the cam grooves 7a, 14a. There is no force exerted by the ball to push out the actuator.

However, if you want to apply the parking brake mechanically, when you rotate the parking brake lever 6, the brake lever shaft 15 rotates, and the actuator 7 is rotated in the circumferential direction via the arm 11 and the link 10. It becomes the force that moves us.

The position of the pin 19 for circumferential rotation in a conventional mechanical disc brake device was provided at the outer edge of the donut-shaped actuator 7, but if it was provided at the outer edge, the configuration of the hydraulic cylinder and parking Since the arrangement of the brake shaft becomes complicated, in this embodiment, it is provided inside the donut shape.
13 is a locking pin for the servo spring.

FIG. 6 shows that when a hydraulic disc brake system is used in addition to the disc brake system of the present invention to brake only one side, that is, when used as a steering brake, the front wheels are automatically braked even in a four-wheel drive state. This allows the drive to be turned off.

However, when the left and right brakes are applied at the same time, the front wheel drive is configured so that it continues to be driven without being cut off.

This means that when performing rotary plowing, adjacent plowing, or transportation, it is necessary to turn with the smallest possible turning radius, but in four-wheel drive mode, the traction force from the front wheels makes it difficult to use the steering brake system, making it difficult to turn. The radius becomes larger. In this case, the four-wheel drive is configured to automatically switch to driving only the rear wheels only when turning using the steering brake.

In FIG. 6, reference numeral E denotes an equalizer device, which connects the hydraulic circuits so that there is no difference between the left and right hydraulic operating forces when braking the left and right brakes simultaneously, that is, when the brakes are used as travel brakes.

The pressure oil that is pushed out from the pistons 3L and 3R integrated with the left and right brake pedals 2L and 2R and flows between the hydraulic cylinder 14 and the actuator 7 is transferred to the switching valve 26 through bypasses 25L and 25R.
It is injected into the left and right oil chambers.

The pressure of this left and right pressure oil is the same pressure because it passes through an equalizer, and the pressure of the brake pedals 2L and 2 is the same.
When R is depressed at the same time, the spool of the switching valve 26 is pushed from the left and right sides and does not move. but,
When only one side is braked as a steering brake, the spool of the switching valve 26 is switched, and the pressure oil between the front wheel drive hydraulic clutch 21 and the front wheel drive clutch braking valve 22 is drained from the bypass 26a to the drain circuit on the switching valve 26 side. As a result, the front wheel drive hydraulic clutch 21 becomes disengaged. 24 is a relief valve, 23
is a hydraulic pump.

(F) Function of the invention The structure of the present invention is as described above, and its function will be explained next.

When an agricultural tractor or the like travels on the road at a relatively high speed for transportation, it is dangerous to brake the left and right sides separately, so a hydraulic brake device is applied simultaneously to the left and right sides as traveling brakes.

Also, when making a small turn on rough terrain or working in rice fields, it is not possible to make a small turn using the steering wheel alone, so in conjunction with the steering wheel operation, it is necessary to use the steering brake, which applies the left and right brakes one at a time. The aircraft then makes a small radius turn.

When the engine is stopped and the vehicle starts on a slope, the parking brake is applied to prevent the vehicle from starting on its own.In the case of this invention, the actuator of the hydraulic disc brake device is also applied in this case. When used as is, by rotating this actuator in the circumferential direction, the ball can be pushed out through the cam groove and a mechanical brake can be applied.

(G) Effects of the Invention Since the present invention is configured as described above, it has the following effects.

First, when performing rotary plowing, adjacent plowing, or transportation, it is necessary to turn with as small a turning radius as possible, but in four-wheel drive mode, even using a steering braking device has little effect due to the traction force from the front wheels. This inevitably increases the turning radius.

In this case, when only one of the left and right brake pedals 2L and 2R is depressed and the steering brake is used to turn, the four-wheel drive will automatically switch to two-wheel drive for the rear wheels only. It became possible to automatically reduce the radius.

Second, when using the left and right brake pedals 2L and 2R as steering brakes to make sharp turns, there is a possibility that dangerous situations may occur due to the large turning radius due to four-wheel drive. However, it is possible to automatically switch from such dangerous four-wheel drive to safe two-wheel drive.

[Brief explanation of drawings]

Fig. 1 is an overall side view of the agricultural tractor, and Fig. 2 is the fourth part of the disc brake device of the present invention.
Fig. 3 is a sectional view taken along line nn, Fig. 4 is a side view, Fig. 5 is a hydraulic circuit diagram of the disc brake device of the present invention, and Fig. 6 is a sectional view taken along line mm in the figure.
The figure is a hydraulic circuit diagram showing a configuration in which a front wheel drive clutch device and a hydraulic disc brake device are linked. 5... Brake disc, 6... Parking brake lever, 7... Actuator, 8... Ball, 14... Hydraulic cylinder, A... Hydraulic extrusion device.

Claims (1)

[Claims] 1 When the left and right brake pedals 2L and 2R are operated simultaneously to simultaneously brake the left and right hydraulic disc brake devices and use them as travel brakes, pressure oil is discharged from the left and right pistons 3L and 3R and reaches the hydraulic cylinders 14 and 14. An equalizer device E is provided to maintain the same pressure, and bypasses 25L and 25R are configured to introduce the pressure oil sent to the hydraulic cylinders 14 and 14 to the left and right sides of the front wheel drive cutoff valve 26 after passing through the equalizer device E, When only one of the left and right brake pedals 2L, 2R is braked, pressure oil from one of the bypasses 25L, 25R flows in, causing the left and right oil chambers of the front wheel drive cutoff valve 26 to become unbalanced, causing the spool to slide, and causing the front wheel drive hydraulic clutch 21
A brake device characterized in that a bypass 26a provided in a front wheel drive cutoff valve 26 is configured to open a bypass 26a provided in a front wheel drive cutoff valve 26 in order to send pressure oil between the front wheel drive clutch brake valve 22 and the front wheel drive clutch brake valve 22 to a drain circuit.