JPS61218468A - Braking device - Google Patents

Abstract

PURPOSE:To make pressure oil in a brake hydraulic chamber at half-braking suddenly go down to the specified pressure and solve a problem on a time lag at the time of suchlike occasion, by installing a quick drain valve interposingly between the brake hydraulic chamber and a brake valve. CONSTITUTION:At the time of normal driving, pressure oil out of a hydraulic source 5 is fed to brakes 2a and 2b via brake valves 4a and 4b whereby they are kept up in a state of being released. At this time, a spool 13 is moved to the side of these brakes 2a and 2b due to a pressure differential with a throttle 12 and energizing force of a spring 14 and a drain port 8 is closed at quick drain valves 6a and 6b. On the other hand, when these valves 4a and 4b are made into half-open at half-braking, pressure oil in these brakes 2a and 2b is pushed out whereby these drain valves 4a and 4b are drained. In this consequence, at the said valves 6a and 6b, the spool 13 moves against the spring 14 and the drain port 8 opens so that the said pressure oil is suddenly drained by way of the said port 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brake device mainly used in crawler-type traveling devices, which operates the brake by spring force and releases the brake by hydraulic pressure. .

BACKGROUND ART This type of brake device is attached to a steering clutch, and operates the brake by draining pressure oil from the oil chamber through the brake pedal, or by operating the steering clutch and pumping pressure into the hydraulic chamber using the steering valve. The brakes are activated by controlling the oil.

The hydraulic chamber of the conventional brake system is directly connected to the brake valve, and the pressure oil in the hydraulic chamber of the brake system is directly controlled by the brake valve. When the brake system is in a half-brake state, the boat leading to the hydraulic chamber of the brake device and the boat leading to the drain are kept half-open, and the amount of drain oil from the hydraulic chamber is controlled to achieve the υ half-brake state. .

Problems to be Solved by the Invention Since the drain circuit of the brake valve is in an early open state in the above-mentioned half-brake state, it takes time to drain the pressure oil from the hydraulic chamber in the brake state, and after the operator operates the brake pedal, There was a long time lag between when the hydraulic pressure in the hydraulic chamber fell to the set pressure and the brake entered a half-brake state, and the operating feel was poor. This problem is especially serious when attempting to slowly turn the track-type traveling device in cooperation with the steering clutch.

Means and Function for Solving the Problems The present invention was conceived in view of the above-mentioned problems, and includes a quick drain valve interposed between the brake hydraulic chamber and the brake valve to reduce the brake hydraulic pressure during half-braking. The pressure oil in the chamber is designed to suddenly drop to a predetermined pressure.

Example Embodiments of the present invention will be described based on the drawings.

In the figure, 1α and lb are left and right clutches provided in one driving section of the left and right Hν band traveling devices, and 2cL#2b are left and right brakes. 3α and 3b are left and right clutch valves, 4cL and 4b are left and right brake valves, and 5 is a hydraulic source that supplies pressure oil to these. 6α, 6b are the left and right brakes 2a,
This is a quick drain valve interposed between the brake valve 2b and the brake valve 3 (Z, 3b).

These quick drain valves 6α, 6b have a drain boat 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.
A valve body 11 having a diameter 9.10, and a spool 13 having a spool 12 (having a spool 13 fitted in a spool hole 7 of the valve body 11) which communicates the bows 9.10 at both ends of the valve body 11 with the shaft center. , a spring 14 that urges this spool 13 toward the boat side on the brake side.
It consists of

In the above configuration, during normal driving, pressure oil from the hydraulic source 5 passes through the brake valves 4α and 4b to the brakes 2a and 2.
It is sent to the hydraulic chamber b and is held in the brake released state. In this case, with the quick drain valves 6α and 6b,
The spool 13 is moved toward the brake side by the differential pressure caused by the throttle 12 and the biasing force caused by the spring 14, and the drain 7I seat 8 is closed.

When half-braking, the brake valves 4α and 4bt are half-open. 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: i) +z and 2b is pushed out from the hydraulic chambers and gradually The brake valves 4α and 4b are machined for draining.For this reason, the quick drain valves 6α and 6b are
Flow in the opposite direction occurs and the quick drain valves 6α, 6
A differential pressure is generated in the school 13 of b due to the throttle DI2, and when this differential pressure becomes greater than the biasing force of the spring 14, the spool 13 moves against the spring 14 and the drain boat 8 is opened). Brake valve 2α.

The pressure oil on the 2b side is rapidly drained through this drain boat S, and the pressure in the brake hydraulic chamber is reduced to the brake valve 2a,
The pressure is rapidly reduced to the pressure set by 2b. When the pressure in the brake hydraulic chamber falls below the set pressure, the spool 13
The drain boat 8 is moved by the spring 14 toward the old brake, and the drain boat 8 is closed, and the pressure in the hydraulic chamber of the brake is maintained at the set pressure.

The semi-braking operation of the brake valves 2a, 2b works together with the gentle operation of the steering valves lcL, lb, so that the traveling device makes a gentle turn.

Effects of the Invention According to the present invention, the pressure oil in the hydraulic chamber of the brake during half-brake operation is drained to the set pressure by the quick drain valves 6α and 6b, thereby eliminating the time lag during half-brake operation.

Therefore, when this brake is used with a clutch in a track-type traveling device, the time lag during slow turns is shortened, and unlike conventional methods, the time lag prevents the user from pulling the lever too much and making unexpected sharp turns (sudden braking). This eliminates this problem and improves the operating feel when turning slowly.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. 2a, 2b are brakes, 4α, 4b are brake valves, 6α
, 6b is a quick drain valve.

Claims (1)

[Claims] In a brake device that operates the brake by spring force and releases the brake by hydraulic pressure, brakes 2a, 2
A brake device characterized in that quick drain valves 6a, 6b are interposed between the hydraulic chamber (b) and the brake valves 4a, 4b.