JPH0674033B2 - Breaking device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device which is mainly used for a crawler type traveling device and which is braked by a spring force and released by hydraulic pressure. .

2. Description of the Related Art A brake device of this type is installed together with a steering clutch.The brake pedal drains pressure oil in the hydraulic chamber to operate the brake, or the steering valve operates the steering clutch to release pressure oil to the hydraulic chamber. The brakes are controlled to operate.

The hydraulic chamber of the conventional brake device is directly connected to the brake valve, and the pressure oil in the hydraulic chamber of the brake device is directly controlled by the brake valve. When the brake system is set to the half-brake state, the port communicating with the hydraulic chamber of the brake device and the port communicating with the drain are opened halfway to control the amount of drain oil from the hydraulic chamber to achieve the half-brake state.

Problems to be Solved by the Invention In the above-mentioned half-brake state, since the drain circuit of the brake valve is in the half-open state, it takes time for the pressure oil to drain from the hydraulic chamber in the brake state, and after the operator operates the brake pedal, the hydraulic pressure is reduced. There was a long time lag until the hydraulic pressure in the room dropped to the set pressure and the brakes were in a semi-braked state, and the operation feeling was poor. This problem was particularly serious when the crawler type traveling device was attempted to make a gentle turn in cooperation with the steering clutch.

Means and Actions for Solving Problems The present invention has been conceived as described above, and in a brake device in which a brake is actuated by a spring force and a brake is released by hydraulic pressure, the brakes 2a, 2b are A quick drain valve 6a that opens between the hydraulic chamber and the brake valves 4a, 4b against the spring by the internal pressure of the hydraulic chambers of the brakes 2a, 2b with the brake valves 4a, 4b switched to the drain side. , 6b is interposed, and when the brake valves 4a, 4b are switched to the drain side in a half-open state by switching to the half-brake state, the pressure in the hydraulic chambers of the brakes 2a, 2b causes the spring to spring. On the contrary, the quick drain valves 6a and 6b are opened, and the pressure oil in the hydraulic chambers of the brakes 2a and 2b is rapidly reduced to a predetermined value.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

In the figure, 1a and 1b are left and right clutches provided in the drive unit of the left and right crawler belt traveling devices, and 2a and 2b are left and right brakes. 3a and 3b are left and right clutch valves, 4a and 4b are left and right brake valves, and 5 is a hydraulic pressure source for supplying pressure oil to these. Reference numerals 6a and 6b are quick drain valves provided between the left and right brakes 2a and 2b and the brake valves 3a and 3b.

The quick drain valves 6a and 6b have a drain port 8 in the middle of the spool hole 7, and one end of the spool hole 7 is connected to the brake side and the other end is connected to the brake valve side.
11 with a valve and ports at both ends of the valve 11 at the axial center
It comprises a spool 13 having a throttle 12 communicating with 9.10 and fitted into the spool hole 7 of the valve body 11, and a spring 14 for biasing this spool 13 toward the port side on the brake side.

In the above configuration, during normal traveling, the pressure oil from the hydraulic pressure source 5 is sent to the hydraulic chambers of the brakes 2a, 2b via the brake valves 4a, 4b and is held in the brake released state. In this case, in the quick drain valves 6a and 6b, the spool 13 is moved to the brake side by the differential pressure of the throttle 12 and the urging force of the spring 14, and the drain port 8 is closed.

At the time of half-brake, the brake valves 4a and 4b are opened halfway. In this state, the hydraulic pressure to the hydraulic chambers of the brakes 2a and 2b stops, and the pressure oil in the hydraulic chambers of the brakes 2a and 2b is pushed out of the hydraulic chambers and gradually drained from the brake valves 4a and 4b. Therefore, a reverse flow occurs in the quick drain valves 6a, 6b, and the spool 13 of the quick drain valves 6a, 6b causes a differential pressure due to the throttle 12, and this differential pressure becomes larger than the biasing force of the spring 14. Then, the spool 13 moves against the spring 14 to open the drain port 8, the pressure oil on the side of the brake valves 2a, 2b is rapidly drained through the drain port 8, and the pressure in the hydraulic chamber of the brake is the brake. The pressure set by the valves 2a and 2b is rapidly reduced. When the pressure in the brake hydraulic chamber falls below the set pressure, the spool 13 is moved to the brake side again by the spring 14, the drain port 8 is closed, and the brake hydraulic chamber pressure is maintained at the set pressure.

The semi-brake operation of the brake valves 2a, 2b causes the traveling device to gently turn by cooperating with the gentle operation of the steering valves 1a, 1b.

EFFECTS OF THE INVENTION According to the present invention, the pressure oil in the hydraulic chamber of the brake at the time of half-brake operation is drained to the set pressure from the quick drain valves 6a, 6b, and the time lag at the time of half-brake operation can be eliminated.

Therefore, when this brake is used in a crawler type traveling device together with a clutch, the time lag during a slow turn is shortened, and the lever is pulled too much due to the time lag, resulting in an unexpected sudden turn (a sudden brake). It is possible to improve the feeling of operation during gentle turning.

[Brief description of drawings]

The drawings are circuit diagrams showing embodiments of the present invention. 2a and 2b are brakes, 4a and 4b are brake valves, and 6a and 6b are quick drain valves.

Claims (1)

[Claims] 1. A brake device in which a brake is actuated by a spring force and a brake is released by hydraulic pressure, and a brake valve 4a, 4b is provided between a hydraulic chamber of the brake 2a, 2b and a brake valve 4a, 4b. The brake device is characterized in that quick drain valves 6a, 6b which are opened against the spring by the internal pressure of the hydraulic chambers of the brakes 2a, 2b in the state where the switch is switched to the drain side are interposed.