JPH062473B2 - Track tension adjustment device for tracked vehicles - Google Patents

Description

The present invention relates to a crawler belt tension adjusting device for a tracked vehicle such as a hydraulic excavator or a crane.

[Prior art]

As a track tension adjusting device for tracked vehicles using hydraulic pressure,
Japanese Patent Publication No. 57-16033 is known. With this configuration, the pressure oil supplied from the hydraulic pressure source is guided to the cylinder (adjuster cylinder) connected to the idler via the pressure reducing valve, and the crawler belt is stretched, and the relief valve that sets the maximum cylinder pressure to the idler is used. When a high pressure is applied, the pressure oil in the cylinder is gradually returned to the tank via the throttle to buffer it.

[Problems to be solved by the invention]

In the above-mentioned known technology, even after the crawler is stretched,
Since the hydraulic force in the cylinder exerts a tension force on the crawler belt, there are disadvantages that links, bushes and the like constituting the crawler belt are worn early and traveling resistance becomes large, resulting in a decrease in fuel consumption rate.

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

[Means for solving problems]

In order to achieve the above object, the present invention provides a cylinder device in which a piston is inserted, a spring that presses the piston in the direction in which the crawler belt is stretched, a hydraulic source that supplies pressurized oil to the head side chamber of the cylinder device, and a hydraulic source. In the track tension adjusting device for a tracked vehicle equipped with a pressure reducing valve interposed in a pipe line connecting between the head side chamber and the head side chamber, a relief valve for setting the maximum pressure of the head side chamber is provided in parallel with the head side chamber of the cylinder device. The rod-side chamber of the cylinder device is connected to a hydraulic pressure source, and a switching valve that switches from a shut-off position to a communication position at a pressure higher than the switching pressure of the pressure reducing valve is interposed in a pipe line that connects the rod-side chamber and the hydraulic pressure source, A pressure reducing valve that switches at a pressure higher than the set pressure of the relief valve is interposed in the pipeline connecting the switching valve and the rod side chamber, and in the pipeline connecting the rod side chamber and the tank,
Means is provided for connecting the rod side chamber to the tank when pressure oil is being supplied from the hydraulic pressure source to the head side chamber through the pressure reducing valve.

[Action]

The track tension adjusting 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 at the pressure set by the pressure reducing valve to move the track. After tensioning, the switching valve is switched by the pressure on the upstream side of the pressure reducing valve, and pressure 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 on the downstream side, and the piston of the cylinder device is It moves toward the head side chamber against the spring, and positions the piston at a position where the pressure of the rod side chamber set by the pressure reducing valve and the spring force and the pressure of the head side chamber are balanced. As a result, the crawler belt is in an optimal tension state. When pressure oil is supplied from the hydraulic pressure source to the head side of the cylinder device and the piston is moving toward the rod side chamber, the rod side chamber communicates with the tank by means for communicating the rod side chamber with 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 a 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 The crawler belt wound around the idler 4, 6 is a hydraulic pressure source for supplying pressure oil to the head side chamber A and the rod side chamber B, and 7 is a first hydraulic line interposed between a hydraulic line 6 and the head side chamber A. A pressure reducing valve, 9 is a check valve which allows only the flow from the pressure reducing valve 7 to the head side chamber A, and 10 is a relief valve interposed between the tank 11 and the head side chamber A for setting the maximum pressure of the head side chamber A. , 12 is an opening / closing valve for connecting the head side chamber A to the tank 11 without passing through the relief valve 10,
13 is a pipe line connecting the upstream side of the pressure reducing valve 7 and the rod side chamber B of the cylinder device 1, 14 is an internal pilot type two-position switching valve (hereinafter referred to as a switching valve) interposed in the pipe line 15, 15
Is a second pressure reducing valve interposed between the switching valve 14 and the rod-side chamber B, 16 is a bypass conduit for guiding the pressure oil in the rod-side chamber B to the switching valve 14 without passing through the pressure reducing valve 15, and 17 is a bypass pipe. A check valve 18 provided in the passage is a relief valve 18 which sets the maximum discharge pressure of the hydraulic power source 6. The switching valve 14 has a switching setting pressure higher than the switching setting pressure of the pressure reducing valve 7, and is in a shut-off position (neutral position) at which the hydraulic power source 6 and the rod-side chamber B are shut off. Road 16,
The check valve 17 communicates with the tank 11, and at the communication position (switching position) b, the hydraulic pressure source 6 communicates with the rod side chamber B through the pressure reducing valve 15 and shuts off the rod side chamber B from the tank 11. The pressure reducing valve 15 is the relief valve 10.
The switch set pressure is higher than the switch set pressure of.

In the above configuration, when the crawler belt 5 is tensioned, the pressure oil from the hydraulic pressure source 6 is guided to the head side chamber A through the pressure reducing valve 7, the conduit 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 the pressure oil in the rod side chamber B is discharged to the tank 11 through the shutoff position a of the pipe line 13, the bypass pipe line 16, the check valve 17, and the switching valve 14. Moves and crawler belt 5 stretches. next,
When the pressure in the head side chamber A reaches the pressure set by the pressure reducing valve 7, the switching valve 14 is switched to the communicating position b using the pressure on the upstream side of the pressure reducing valve 7 as the bias pressure, and the pressure oil of the hydraulic pressure source 6 is piped. It flows into the rod-side chamber B through the passage 13, the communication position B of the switching valve 14, and the pressure reducing valve 15. When the pressure of the rod-side chamber B thus generated reaches a value exceeding the pressure of the head-side chamber A set by the relief valve 10 and the spring force of the spring 3, the pressure oil of the head-side chamber A is discharged through the relief valve 10. The piston 2 is returned in the head side chamber A direction by X amount. At this position, the pressure of the head side chamber A and the spring force of the spring 3 are balanced with the pressure of the rod side chamber B set by the pressure reducing valve 15. Therefore, the idler 4 also moves and the crawler belt 5 slightly loosens, but the amount of looseness is a very small amount that does not affect the running of the vehicle.

〔The invention's effect〕

According to the crawler belt tension adjusting device for a track-type vehicle of the present invention described above, the tension of the crawler belt can be optimized because the tension is not always applied to the crawler belt by hydraulic pressure after the crawler belt is tensioned. Therefore, it is possible to reduce the wear of the crawler belt and the supporting portion of the crawler belt, reduce the running resistance, and improve the fuel consumption rate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of a track tension adjusting device for a tracked vehicle according to the present invention. 1 ... Cylinder device, 2 ... Piston, 3 ... Spring, 5 ... Crawler belt, 6 ... Hydraulic source, 7,15 ... Pressure reducing valve, 8, 13 ... Pipe line,
10 ... Relief valve, 11 ... Tank, 14 ... Switching valve, 16
… Pilot conduit, 17… Check valve.

Claims (2)

[Claims] 1. A cylinder device having a piston inserted therein, a spring for pressing the piston in the direction in which the crawler belt is stretched, a hydraulic pressure source for supplying pressure oil to the head side chamber of the cylinder device, and a pipe connecting the hydraulic source and the head side chamber. In a track tension adjusting device of a tracked vehicle equipped with a pressure reducing valve interposed in a road and a relief valve for setting the maximum pressure of the head side chamber, a rod side chamber of the cylinder device is provided with a hydraulic power source in parallel with the head side chamber of the cylinder device. To the pipe line connecting the rod side chamber and the hydraulic power source,
A decompression in which a switching valve that switches from a shut-off position to a communication position at a pressure higher than the switching pressure of the pressure reducing valve is interposed, and a pressure that is higher than the pressure set by the relief valve is switched to a pipeline connecting the switching valve and the rod side chamber. A means for connecting the rod-side chamber to the tank when pressure oil is being supplied from the hydraulic source to the head-side chamber through a pressure reducing valve is provided in a pipeline connecting the rod-side chamber and the tank with a valve interposed. A track tension adjusting device for tracked vehicles. 2. A bypass line for guiding the pressure oil in the rod side chamber to a switching valve without passing through the pressure reducing valve connected to the rod side chamber, a check valve interposed in the bypass line, and a shut-off position. The track tension adjusting device for a tracked vehicle according to claim 1, characterized in that the switching side valve connects the rod side chamber to the tank.