JPS62258874A - Crawler tension regulating device for crawler type vehicle - Google Patents

Abstract

PURPOSE:To reduce the friction between a crawler and a crawler support section, by providing a pilot type check valve which uses the pressure upstream of a selector valve as a pilot pressure so that a closed condition is sustained to set the tension of the crawler at an optimum value. CONSTITUTION:A pilot check valve 16 is operated by the pressure upstream of a selector valve 14 as a pilot pressure and is therefore opened to communicate a rod side chamber B with a tank 11. Further, hydraulic oil from a hydraulic pressure source 6 is led into a head side chamber A through a pressure reducing valve 7, a pipe line 8 and a check valve 9 so that a piston 2 is pushed out by the pressure set at the pressure reducing valve 7 and the spring force of a spring 3 while hydraulic oil in the rod side chamber B is discharged from a tank 11 through the valve 16 which is opened by the pressure upstream of the selector valve 14. Accordingly, an idler is displaced to stretch the tension of a crawler 5 so that the set pressure is obtained, and therefore, the valve 14 is changed over to balance with the pressure in the rod side chamber B due to the valve 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a track tension adjustment device for tracked vehicles such as hydraulic excavators and cranes.

[Prior art]

As a track tension adjustment device for tracked vehicles using hydraulic pressure,
Japanese Patent Publication No. 57-16033 is known.

In this configuration, pressure oil supplied from a hydraulic source is guided to a cylinder (adjuster cylinder) connected to an idler via a pressure reducing valve (thereby, a relief valve that sets the maximum pressure of the cylinder on the idler) When higher pressure is applied, the pressure oil in the cylinder is gradually returned to the tank via the throttle to buffer it.

[Problem that the invention seeks to solve]

In the above-mentioned known technology, even after the track is tensioned,
Since tension is applied to the track due to the hydraulic pressure in the cylinder, the links, bushings, etc. that make up the track wear prematurely, and running resistance increases, resulting in a lower fuel consumption rate.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crawler belt tension adjustment device for a tracked vehicle that can optimize the tension of the belly belt.

[Means for solving problems]

In order to achieve the above object, the present invention provides a cylinder device into which a piston is inserted, a spring that presses the piston in the direction in which the crawler track is tensioned, a hydraulic source that supplies pressure oil to a head side chamber of the cylinder device, and a hydraulic source. In a seven-band tension adjustment device for a tracked vehicle, which is equipped with a pressure reducing valve interposed in a conduit connecting the head side chamber and a relief valve that sets the maximum pressure of the head side chamber, the seven-band tension adjustment device is arranged in parallel with the head side chamber of the cylinder device. A rod side chamber of the cylinder device is connected to a hydraulic power source, and a switching valve that switches from a blocking position to a communicating position at a pressure higher than the switching pressure of the pressure reducing valve is interposed in a pipe line connecting the rod side chamber and the hydraulic power source. , a pressure reducing valve that switches at a pressure higher than the set pressure of the relief valve is interposed in the pipe line connecting the switching valve and the rod side chamber, and the pipe line connecting the rod side chamber and the tank,
The present invention is characterized in that a pilot type check valve is provided that maintains the open state by using the pressure upstream of the switching valve as a pilot pressure when pressure oil is supplied from the hydraulic pressure source to the head side chamber through the pressure reducing valve.

[Effect]

The track tension adjustment device for a tracked vehicle configured as described above supplies pressure oil from the hydraulic source to the head side chamber of the cylinder device through the pressure reducing valve, and presses the piston with the pressure set by the pressure reducing valve to tighten the track. After the tension is increased, the switching valve is switched by the pressure on the upstream side of the pressure reducing valve, and pressurized oil is supplied from the hydraulic source to the rod side chamber of the cylinder device through the switching valve and the pressure reducing valve located downstream of the switching valve, and the piston of the cylinder device is The piston is moved toward the head side chamber against the spring and positioned at a position where the pressure in the rod side chamber set by the pressure reducing valve, the spring force, and the pressure in the head side chamber are balanced.

This creates the optimal tension for covering. Note that when pressure oil is supplied from the hydraulic source to the head side of the cylinder device and the piston is moving toward the rod side chamber, the rod side chamber is supplied with pressure oil through the pilot type check valve, which is in an open state due to the pressure on the upstream side of the switching valve. It is connected to the tank.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. In this figure, 1 is a cylinder device (adjuster cylinder) into which the piston 2 is inserted, 3 is a spring inserted into the head side chamber A to press the piston 2, 4 is an idler with which the piston 2 is in contact, and 5 is an idler. 6 is a hydraulic power source that supplies pressurized oil to the head side chamber A and the rod side chamber B; 7 is a first pipe 8 that connects the hydraulic power source 6 and the head side chamber A; 9 is a check valve that allows flow only from the pressure reducing valve 7 to the head side chamber type, and 10 is a relief interposed between the tank 11 and the head side chamber A in order to set the maximum pressure of the head side chamber A. Valve 12 is an on-off valve 1 that connects the head side chamber A to the tank 11 without passing through the relief valve 10.
3 is the upstream side of the pressure reducing valve 7 and the rod side chamber B of the cylinder arrangement f1.
14 is an internal pilot type two-position switching valve (hereinafter referred to as a switching valve) interposed in the pipe 13; 15;
16 is a second pressure reducing valve interposed between the switching valve 14 and the rod side chamber B, and 16 is a pilot type valve that opens using the upstream pressure of the switching valve 14 as pilot pressure and communicates the rod side chamber B with the tank 11. The check valve 17 is a relief valve that sets the maximum discharge pressure of the hydraulic source 6. The switching valve 14 has a switching set pressure higher than the switching setting pressure of the pressure reducing valve 7, and cuts off the hydraulic pressure a6 and the rod side chamber B at the blocking position (neutral position W,) A, and at the communicating position (switching position) At this point, the hydraulic power source 6 and the rod side chamber B are communicated through the pressure reducing valve 15, and the rod side chamber B is cut off from the tank 11. The pressure reducing valve 15 has a switching set pressure higher than the switching setting pressure of the relief valve 10.

In the above configuration, when tensioning the abdominal band 5, pressure oil from the hydraulic source 6 is guided to the head side chamber A through the pressure reducing valve 7, the pipe line 8, and the check valve 9, and the piston 2 is set by the pressure reducing valve 7. The idler 4 is pressed by the pressure and the spring force of the spring 3, and discharges the pressure oil in the rod side chamber B into the tank 11 through the pilot check valve 16, which is opened by the pressure on the upstream side of the switching valve 14. Move, track 5
is tense. Next, when the pressure in the head side chamber A reaches the pressure set by the pressure reducing valve 7, the switching valve 14 switches from the blocking position A to the communicating position using the pressure on the upstream side of the pressure reducing valve 7 as a pilot pressure, and the hydraulic Pressure oil from the source 6 flows into the rod side chamber B through the pipe line 13, the communication position port of the switching valve 14, and the pressure reducing valve 15. At this time, the pilot type check valve is closed. When the pressure in the rod side chamber B generated by this reaches a value that exceeds the pressure in the head side chamber A set by the relief valve 10 and the spring force of the spring 3, the pressure oil in the head side chamber A is discharged through the relief valve 10. The piston 2 is returned by x52 in the direction of the head side chamber A. At this position,
The pressure to the head side chamber, the spring force of the spring 3, and the pressure reducing valve 15
The pressure in the rod side chamber B is balanced. Therefore, the idler 4 also moves and the crawler track 5 loosens a little, but
This amount of slack is extremely small and does not affect the running of the vehicle.

〔Effect of the invention〕

According to the crawler belt tension adjustment device for a tracked vehicle of the present invention as described above, after the crawler belt is tensioned, no tension force is constantly applied to the crawler belt due to hydraulic pressure, so that the tension of the crawler belt can be kept in an optimal state. Therefore, it is possible to reduce the wear of the crawler belt and the support portion of the crawler belt, and also to reduce the running resistance and improve the fuel consumption rate.

[Brief explanation of drawings]

The figure is a circuit diagram showing an embodiment of a track tension adjustment device for a tracked vehicle according to the present invention. DESCRIPTION OF SYMBOLS 1...Cylinder device, 2...Piston, 3...Spring, 5...Crawler track, 6...Hydraulic pressure source, 7°15...Reducing valve, 8, 13...Pipe line, 10...Relief valve, 1
1...tank, 14... 1 switching valve, 1
6...Pilot type check valve.

Claims (1)

[Claims] 1. A cylinder device into which the piston is inserted, a spring that presses the piston in the direction in which the crawler track is tensioned, a hydraulic source that supplies pressure oil to the head side chamber of the cylinder device, and a pipe that connects the hydraulic source and the head side chamber. In a track tension adjustment device for a tracked vehicle equipped with a pressure reducing valve and a relief valve that sets a maximum pressure in a head side chamber, the rod side chamber of the cylinder device is connected to a hydraulic power source in parallel with the head side chamber of the cylinder device. ,
A switching valve that switches from a blocking position to a communicating position at a pressure higher than the switching pressure of the pressure reducing valve is interposed in a pipe connecting the rod side chamber and the hydraulic source, and a pipe connects the switching valve and the rod side chamber. A pressure reducing valve that switches at a pressure higher than the set pressure of the relief valve is interposed in the pipe line connecting the rod side chamber and the tank, and when pressure oil is being supplied from the hydraulic source to the head side chamber through the pressure reducing valve. A track tension adjustment device for a tracked vehicle, comprising a pilot type check valve that maintains an open state by using pressure upstream of the switching valve as a pilot pressure.