JPH0229556B2 - RITAITSUKISAGYOKINOSOKOYUATSUKAIRO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a travel hydraulic circuit for a work machine with a crawler track, which is equipped with an adjuster cylinder that adjusts and cushions the tension of the track.

In a crawler-equipped work machine that travels using a crawler track, a known adjuster cylinder is used to apply a predetermined tension to the crawler track and to buffer the tension caused by an external force on the crawler track. The operation of this adjuster cylinder will be outlined based on FIG. 1.

FIG. 1 is a sectional view of the schematic structure of an adjuster cylinder. In the figure, 1 is the side frame of the traveling body,
2 is a stopper supported by the side frame 1;
is an adjuster cylinder, 4 is a piston, 5 is a piston rod fixed to the stopper 2, 6 is a partition plate that divides the adjuster cylinder 3, 7 is a grease chamber between the piston 4 and the partition plate 6, 8 is a piston, 9 is a piston rod, and 10 is a hydraulic oil chamber formed by the piston 8 and the partition plate 6 and filled with oil. The piston rod 9 is installed on the side frame 1 so as to be movable in the longitudinal direction, and is fixed to a yoke that rotatably supports an idler around which a crawler belt is wound. 11 is a hydraulic oil accumulator, which is communicated with the hydraulic oil chamber.

After winding the track around the idler, when grease is injected into the grease chamber 7 by an appropriate means, the pressure of the injected grease causes the adjuster cylinder 3,
The piston rod 9 therefore moves to the right, pushing outward the yoke supporting the idler. As a result, the idler also moves outward, and the track wrapped around the idler becomes tense. The degree of tension in the track is adjusted by the pressure of the grease. While the work equipment is running, if the track gets caught in a foreign object such as a stone, causing abnormal tension in the track, or if the track receives a sudden impact force, the piston rod 9 and piston 8 move to the left, causing the hydraulic fluid to drain. Since the oil in the chamber 10 escapes to the accumulator 11, abnormal tension in the crawler track is buffered.

In such a device, the buffering effect against abnormal tension in the crawler track is, as is clear from the above configuration,
This is achieved only by the pressure absorption effect of the gas pressure of the accumulator 11. For this reason,
Accumulator 11 due to long-term use of work equipment
When the filled gas pressure is released, the pressure absorption effect of the accumulator 11 decreases, and the circuit pressure of the hydraulic oil tends to become higher than the initial set pressure.If abnormal tension occurs, it cannot be absorbed, and the shock This has caused a disadvantage in that this directly acts on the adjuster cylinder 3 and damages the adjuster cylinder 3 itself or structures such as the bracket around it. Conventionally,
In order to prevent this drawback, a relief means is provided at a location communicating with the grease chamber 7 or the hydraulic oil chamber 10,
Although it was designed to release the generated pressure, even with such a relief means, once the adjuster cylinder 3 reaches the stroke end after the relief is performed, the relief effect disappears at all after that, and the above-mentioned drawback remains. Become.

The present invention has been made in view of the above circumstances, and its purpose is to prevent damage to the adjuster cylinder or the surrounding structures when abnormal tension occurs in the crawler track, even if the gas pressure in the accumulator is reduced. An object of the present invention is to provide a travel hydraulic circuit for a tracked work machine that can prevent the above problems.

To achieve this objective, the present invention detects the pressure in the grease chamber or hydraulic oil chamber of the adjuster cylinder, and when this pressure exceeds a certain predetermined value, the control valve of the hydraulic motor that drives the work equipment is set to neutral. It is characterized in that the working machine is stopped at the same position.

The present invention will be explained below based on the embodiments shown in FIGS. 2 and 3.

FIG. 2 is a circuit diagram of a traveling hydraulic circuit of a crawler-equipped work machine according to a first embodiment of the present invention. In the figure, the configurations of the adjuster cylinder 3 and the accumulator 11 are the same as those shown in FIG. 1, and the point that the hydraulic oil chamber 3 and the accumulator 11 are connected is also the same. 12 is a hydraulic pump mounted on the working machine; 13 is a travel motor driven by pressure oil in the main circuit, although it is not shown in this figure; and 14 is a drive motor interposed between the main circuit and the hydraulic motor 13. Control valves 14F and 14R for controlling the drive of the hydraulic motor 13 are pilot chambers on both sides of the control valve 14, respectively. 15 indicates a pilot valve, forward pilot valve 1
5F and a reverse pilot valve 15R. When the forward pilot valve 15F is switched, it is switched from the lower position in the figure to the upper position, and the hydraulic pressure from the hydraulic pump 12 is transmitted to the pilot chamber 14F of the control valve 14.
Also, when the reverse pilot valve 15R is switched, a similar switch is performed, and the hydraulic pressure from the hydraulic pump 12 is transferred to the pilot chamber 14 of the control valve 14.
transmitted to R. 16 is a shuttle valve for selecting the high pressure side, and 17 is a hydraulic oil tank. Reference numeral 18 denotes a switching valve having a pilot chamber 18P, to which the pressure of the circuit between the adjuster cylinder 3 and the accumulator 11 is introduced via a pilot conduit. When the switching valve 18 is in the normal position, one end of the shuttle valve 16 is connected to the hydraulic oil tank 17, but when the switching valve 18 is switched to the lower position in the figure, the shuttle valve 1
One end of 6 is connected to a hydraulic pump 12.

Now, when the forward pilot valve 15F is operated, the hydraulic pressure from the hydraulic pump 12 is transferred to the shuttle valve 16.
is transmitted to the pilot chamber 14F of the control valve 14, the control valve 14 is switched to the upper position in the figure, the hydraulic motor 13 rotates normally, and the working machine moves forward. During this running, if the crawler belt becomes abnormally tense due to foreign matter such as a stone being caught in the crawler belt, the adjuster cylinder 3 and the accumulator 11 exhibit the above-mentioned buffering effect to absorb the impact. in this case,
If the gas pressure in the accumulator 11 is decreasing,
The circuit pressure between the accumulator 11 and the hydraulic oil chamber 10 increases. This circuit pressure is introduced into the pilot chamber 18P of the switching valve 18 via the pilot pipe,
When the circuit pressure is higher than the set pressure set by the switching valve 18, the switching valve 18 is switched to the lower position. As a result, the hydraulic pressure of the hydraulic pump 12 is transmitted to both pilot chambers 14F, 14R of the control valve 14 via both shuttle valves 16, and these are switched to the neutral position. Therefore, the hydraulic motor 13 stops and the working machine also stops. by the way,
The above-mentioned abnormal tension is caused by the running of the work equipment, whether it is when the track gets caught in a foreign object or when it receives a sudden impact force. When this stops, this abnormal tension also disappears. In this way, damage to the adjuster cylinder or the surrounding structure is prevented, and no excessive force is applied to the vehicle body.

When the abnormal tension disappears, the circuit pressure decreases, the switching valve 18 returns, the control valve 14 is also switched to the upper position, the hydraulic motor 13 restarts rotation, and the work implement automatically moves forward again. In this case, if the abnormal tension is due to a foreign object being caught, the abnormal tension will occur again as the robot moves forward.
At this time, if you move the work machine backwards,
In many cases, the trapped foreign object will be removed and the vehicle will be able to continue driving without any problems.

In this way, in this embodiment, when the circuit pressure exceeds a predetermined value, the control valve is switched to apply pressure from the hydraulic pump to the pilot chambers at both ends of the control valve at the same time, and the control valve is placed in the neutral position. Since the adjustment is stopped, damage to the adjuster cylinder and surrounding structures can be prevented, and undue force is not generated on the vehicle body.

FIG. 3 is a circuit diagram of a travel hydraulic circuit for a tracked work machine according to a second embodiment of the present invention. In the figure, the second
The same parts as those shown in the figures are given the same reference numerals. Reference numerals 19F and 19R are switching valves respectively provided for the pilot chambers 14F and 14R at both ends of the control valve 14, each having a pilot chamber 19P. In the pilot room 19P,
The pressure in the circuit between the hydraulic oil chamber 10 and the accumulator 11 is guided. The switching valves 19F and 19R are in the upper position in the figure in the normal state, and are located in the upper position in the figure.
When the pressure at P is above a predetermined pressure, it is switched to the lower position in the figure.

Now, when the forward pilot valve 15F is operated, the hydraulic pressure of the hydraulic pump 12 is transmitted to the pilot chamber 14F of the control valve 14 via the forward pilot valve 15F and the switching valve 19F, and the control valve 14 is switched to the upper position to control the hydraulic motor. 13 in the normal direction to move the work machine forward. While the work machine is moving forward, the circuit pressure is applied to the switching valves 19F and 19R.
When the pressure exceeds the set value, both switching valves 1
9F and 19R are switched to the lower position, and the pilot chambers 14F and 1 at both ends of the control valve 14
4R is connected to the hydraulic oil tank 17. As a result, the control valve 14 returns to the neutral position and the work machine stops. When the abnormal tension disappears due to the stoppage of the work equipment, the circuit pressure decreases and the switching valve 19
F and 19R return to their original positions, the control valve 14 returns from the neutral position to the upper position, the hydraulic motor 13 rotates forward, and the work machine automatically restarts forward movement.

In this way, in this embodiment, when the circuit pressure exceeds a predetermined value, the switching valve is switched, the pilot chambers at both ends of the control valve are set to tank pressure, the control valve is set to the neutral position, and the work machine is stopped. Therefore, the same effect as the previous embodiment is obtained.

In addition, in the description of each of the above embodiments, the circuit pressure between the hydraulic oil chamber and the accumulator is detected, but it is also possible to detect the pressure in the grease chamber and switch the switching valve.

As described above, in the present invention, the pressure in the pressure chamber of the adjuster cylinder is detected, and when the detected pressure is equal to or higher than a predetermined pressure, the control valve is set to the neutral position and the working machine is stopped. Damage to the star cylinder and surrounding structures can be prevented, and no excessive force is applied to the vehicle body.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a schematic configuration of an adjuster cylinder, and FIGS. 2 and 3 are circuit diagrams of traveling hydraulic circuits of crawler-equipped work machines according to first and second embodiments of the present invention, respectively. 3...Adjuster cylinder, 7...Grease chamber, 10...Hydraulic oil chamber, 11...Accumulator, 12...Hydraulic pump, 13...Hydraulic motor,
14... Control valve, 15... Pilot valve, 16... Shuttle valve, 18, 19F,
19R...Switching valve.

Claims (1)

[Claims] 1. In a travel hydraulic circuit for a work machine with a crawler track, which is equipped with an adjuster cylinder that adjusts tension and buffers the track, a hydraulic motor for travel, and a control valve that controls the drive of the hydraulic motor, A running hydraulic pressure for a tracked working machine, characterized in that it is provided with a detection means for detecting the pressure in a pressure chamber, and a means for setting the control valve to a neutral position when the value detected by the detection means is equal to or higher than a predetermined value. circuit.