JPH064428B2 - 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 a track-type vehicle using hydraulic pressure,
Japanese Patent Publication No. 57-16033 is known. In 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, so that the crawler belt is stretched and higher than the relief valve that sets the maximum cylinder pressure in the idler. When pressure is applied,
The pressure oil in the cylinder is returned to the tank to buffer it.

[Problems to be solved by the invention]

In the above-mentioned known technique, since the cushioning characteristic is determined by the switching set pressure of the relief valve, a sufficient cushioning force may not be obtained when the action speed of the external force acting on the idler changes.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a track tension adjusting device for a tracked vehicle that can automatically change the cushioning force according to a change in the action speed of an external force. There is.

[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 pressure oil to the head side chamber of the cylinder device, and a head side chamber. In a track tension adjusting device for a tracked vehicle equipped with a relief valve for setting the maximum pressure of the relief valve, and means for outputting a signal according to the movement amount of the piston, and switching setting of the relief valve by the signal from the means. It is characterized in that setting means for changing the value is provided.

[Action]

When the action speed of the external force acting on the piston from the crawler belt changes, a signal is output from the means for outputting a signal according to the movement amount of the piston according to the change, and this signal changes the switching set value of the relief valve. Since the relief valve switching setting value is input to the setting means and automatically changes, the cushioning force of the relief valve changes according to the action speed of the external force.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. 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 Crawler track hung around idler 4, 6
Is a hydraulic pressure source for supplying pressure oil to the head side chamber A, and 7 is a hydraulic pressure source 6
And a pressure reducing valve interposed in a pipe line 8 connecting the head side chamber A to the head side chamber A, a check valve 9 for allowing only flow from the pressure reducing valve 7 to the head side chamber A, and a main relief 10 for setting a maximum discharge pressure of the hydraulic pressure source 6. A valve, 11 is a relief valve interposed between the tank 12 and the head side chamber A in order to set the maximum pressure of the head side chamber A, and 13 is a pipe line connecting the rod side chamber B of the cylinder device 1 and the tank 12. Is. Further, 14 is a means for outputting a signal according to the amount of movement of the piston 2, which means a link 15 fixed to the idler 4, a cylinder 17 into which a piston 16 moving integrally with the link 15 is inserted,
An oil reservoir 19 that supplies oil to the head side chamber of the cylinder 17 via a check valve 18, and the rod side chamber of the cylinder 17 to the tank 1
The cylinder 17 includes a passage 20 connected to the cylinder 2. The cylinder 17 moves pressure oil corresponding to the movement amount (that is, a signal corresponding to the movement amount) from the head side chamber by the movement of the idler 4 that moves together with the piston 2 of the cylinder device 1. Supply (that is, output). The check valve 18 and the oil sump 19 are for ensuring the minimum pressure in the head side chamber of the cylinder 17 and for preventing backflow from the head side chamber to the oil sump 19. Further, 21 is a setting means for changing the switching set value of the relief valve 11, and the setting means is the spring 2 of the relief valve 11.
It is constituted by a cylinder 24 into which a piston 23 that presses 2 is inserted. The cylinder 24 receives pressure oil supplied from the head side chamber of the cylinder 17 through a pipe line 25 (that is, input), and the piston 23 is caused by this pressure oil. Moving.

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 of the cylinder device 1 through the pressure reducing valve 7, the pipe line 8 and the check valve 9 to move the piston 2 to the pressure reducing valve 7. The pressure oil in the rod-side chamber B is pushed through the pipe line 13 and the tank 12
The discharger moves the idler 4 and the crawler belt 5 is stretched. In this state, when the pressure in the head side chamber A reaches a value exceeding the pressure set by the relief valve 11 and the pressing spring force of the spring 3 due to the external force acting on the idler 4, the pressure oil in the head side chamber A is released. Is discharged to the tank 1 through and the piston 2 is returned to the head side chamber A direction. At this time, the piston 16 moves along with the movement of the idler 4, and the pressure oil in the head side chamber of the cylinder 17 is guided to the cylinder 24 through the pipe line 25, and the piston 23 presses the spring 22 by this pressure oil and the relief is performed. Valve 11
Increase the switching setting value of. FIG. 2 shows changes in the relief pressure (that is, the switching set value) of the relief valve 11 with respect to the amount of idler movement. As can be seen from this figure, the relief pressure of the relief valve 11 increases as the amount of idler movement increases. , Is getting higher. Therefore, even when the action speed of the external force acting on the idler 4 changes, the relief valve 1 provides an optimum cushioning force by changing the switching set value of the relief valve 11 according to the change. Also,
The external force acting on the idler 4 becomes smaller and the piston 2
Is pressed in the direction in which the crawler belt 5 is stretched by the pressure set by the pressure reducing valve 7 and the spring force of the spring 3, the piston 16
Also moves with the idler 4, the pressure in the head side chamber of the cylinder 17 decreases, the pressure in the cylinder 24 also decreases, and the switching set value of the relief valve 11 decreases.

〔The invention's effect〕

According to the track tension adjusting device for a tracked vehicle of the present invention described above, the switching set value of the relief valve that sets the pressure of the head side chamber of the cylinder device is automatically set according to the movement amount of the piston that stretches the track. Since it can be changed, the buffering force can be automatically changed according to the change in the action speed of the external force. Therefore, the buffer characteristic can be improved.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing one embodiment of a track tension adjusting device for a tracked vehicle of the present invention, and FIG. 2 is a characteristic diagram showing the relationship between the amount of idler movement and the relief pressure of a relief valve. . 1 ... Cylinder device, 2 ... Piston, 3 ... Spring, 5
...... Crawler track, 6 ...... Hydraulic pressure source, 11 ...... Relief valve, 14 ...
... means, 21 ... setting means.

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 source for supplying pressure oil to the head side chamber of the cylinder device, and a relief valve for setting the maximum pressure of the head side chamber. In a crawler belt tension adjusting device for a tracked vehicle comprising: a means for outputting a signal according to the moving amount of the piston, and a setting means for changing the switching set value of the relief valve by a signal from the means. A crawler belt tension adjusting device for a tracked vehicle characterized by being provided.