JPH064427B2 - 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 tension force acts on the crawler belt due to the hydraulic pressure of the cylinder, there are disadvantages that the links, bushes, etc. constituting the crawler belt are quickly worn, the running resistance is increased, and the fuel consumption rate is reduced.

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. And a head side chamber, a pressure reducing valve interposed in a pipe line connecting the head side chamber and a relief valve for setting the maximum pressure of the head side chamber, in a track tension adjusting device for a tracked vehicle, in parallel with the head side chamber of the cylinder device. A rod side chamber of the cylinder device is connected to a hydraulic pressure source, and a switching valve that switches from a cutoff position to a communication position at a pressure higher than the switching pressure of the pressure reducing valve is interposed in a pipeline connecting 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,
It is characterized in that a pilot type check valve is provided which maintains an open state by using the pressure on the upstream side of the switching valve as a pilot pressure when pressure oil is being supplied from the hydraulic pressure source to the head side chamber through a 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 with the pressure set by the pressure reducing valve to move the track. After tightening, the switching valve is switched by the pressure on the upstream side of the pressure reducing valve, 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 The piston moves to the direction of the head side chamber against the spring, and the piston is positioned at a position where the pressure of the rod side chamber set by the pressure reducing valve balances the spring force and the pressure of the head side chamber. This creates the optimum tension for the track. 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 passes through a pilot type check valve that is open due to the pressure on the upstream side of the switching valve. It communicates 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 A 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 that allows flow only 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 to set the maximum pressure of the head side chamber A. , 12 are opening / closing valves for connecting the head side chamber A to the tank 11 without passing through the relief valve 10,
Reference numeral 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 13, 15
Is a second pressure reducing valve interposed between the switching valve 14 and the rod side chamber B, and 16 is a pilot type that opens the rod side chamber B to the tank 11 by using the pressure on the upstream side of the switching valve 14 as the pilot pressure. The check valve 17 is a relief valve that 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, shuts off the hydraulic power source 6 and the rod side chamber B at the shut-off position (neutral position) b, and at the communication position (switching position) b. The hydraulic pressure source 6 and the rod side chamber B are communicated with each other through the pressure reducing valve 15, and the rod side chamber B is shut off from the tank 11.
The pressure reducing valve 15 has a switching setting pressure higher than the switching setting pressure of the relief valve 10.

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 pushed 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 pilot type check valve 16 which is in the open state due to the pressure on the upstream side of the switching valve 14. Move and crawler 5
Stretch. Next, when the pressure in the head side chamber A reaches the pressure set by the pressure reducing valve 7, the pressure on the upstream side of the pressure reducing valve 7 is used as the pilot pressure, and the switching valve 14 switches from the shut-off position (i) to the communication position (b). The pressure oil of the source 6 flows into the rod side chamber B through the conduit 13, the communication position B of the switching valve 14, and the pressure reducing valve 15. At this time, the pilot type check valve is closed. 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 in 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 the amount X. At this position, the pressure of the head side chamber A and the spring force of the spring 3 and the pressure of the rod side chamber B set by the pressure reducing valve 15 are balanced.
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 of the crawler belt is not always exerted by the 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 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, 1
1 ... Tank, 14 ... Switching valve, 16 ... Pilot type check valve.

Claims (1)

[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 pressure source and the head side chamber. In a track tension adjusting device for a tracked vehicle equipped with a pressure reducing valve interposed in a passage 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 pressure source in parallel with the head side chamber of the cylinder device. To the pipe line that connects the rod side chamber and the hydraulic source.
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 reducing pressure that switches to a pipe line connecting the switching valve and the rod side chamber at a pressure higher than the set pressure of the relief valve. When pressure oil is supplied from the hydraulic pressure source to the head side chamber through the pressure reducing valve to the pipe line connecting the rod side chamber and the tank with the valve interposed, the pressure on the upstream side of the switching valve is opened as the pilot pressure. A track tension adjusting device for a tracked vehicle, which is provided with a pilot type check valve for maintaining the state.