JPH04272333A - Oil-hydraulic circuit for service-machine-interference-proof equipment - Google Patents

Abstract

PURPOSE:To stop a service machine gradually regardless of an engine rotational- speed or a service machine operating lever position by stopping pressure oil to a service machine operating valve working pilot valve, gradually when the service machine comes into an interference-dangerous area for facilitating interference to an operating room. CONSTITUTION:The upstream side of a pilot valve 14 for working a service machine operating valve 18 is provided with a solenoid valve 4. The solenoid valve 4 is switched to positions 5, 6, 7 gradually according to signal from a judgement means 22 for judging that a service machine comes into an interference-dangerous area for facilitating interference to an operating room. By this switching, pressure oil to the pilot valve 14 is gradually stopped. Accordingly, even if a service machine operating lever 15 is set at a service machine operating position, the spool of the service machine operating valve 18 is returned to a neutral position, and the service machine is stopped.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a work machine interference prevention device for preventing interference with a driver's cab of a work machine in a work vehicle such as a power shovel.

0002

2. Description of the Related Art This type of prior art is previously proposed in Japanese Patent Laid-Open No. 1-142133. This is because in a work vehicle such as a power shovel that has a work arm mechanism with a parallelogram configuration in which a part of the articulated work machine arm link mechanism that makes bending movements can be offset in the lateral direction, the work machine If excavation and loading work is performed while offset to the front side of the operator's cab, the operating range of the implement includes an area that interferes with the operator's cab, making operation of the implement dangerous.

[0003] In order to eliminate such dangerous operations, when the work equipment enters a dangerous area where it is likely to interfere with the operator's cab, a signal from the judgment means notifies the driver with a buzzer, and when the work equipment reaches the stop position, a solenoid valve is activated. to operate the stop cylinder and return the work equipment control lever to the neutral position. This stops the flow of oil from the work machine operating valve to the work machine hydraulic cylinder, stopping the work machine.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional configuration, when the work equipment enters a dangerous area where it is likely to interfere with the operator's cab, it is difficult to control the work equipment depending on the engine rotational speed or the operating position of the work equipment control lever at that time. The speeds are different, and if the work equipment speed is high, it will stop suddenly. This has the drawback that the shock to the vehicle body is large, causing discomfort to the driver, and the shock causes cargo such as dirt in the bucket to spill out, posing a danger to the driver and surrounding workers.

[0005] In view of the problems of the above-mentioned prior art, the present invention
The purpose of this invention is to provide a hydraulic circuit for a work equipment interference prevention device that gradually stops the work equipment and reduces shock to the vehicle body even when the work equipment enters a dangerous area where it is likely to interfere with the operator's cab at high speed. do.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the hydraulic circuit of the work machine interference prevention device according to the present invention is designed to operate in an interference danger area where a work machine operated by a hydraulic actuator is likely to interfere with the operator's cab. In a work equipment interference prevention device that stops the work equipment based on a signal from a judgment means that determines whether the work equipment enters an interference danger area, a solenoid valve is provided on the upstream side of a pilot valve for operating the work equipment operation valve. , the solenoid valve is
The position is gradually switched in response to a signal from the determining means, and the pressure oil to the pilot valve is gradually stopped. In addition, even if the work machine control lever is in the work machine operation position, the spool of the work machine control valve returns to the neutral position and the work machine stops.

[0007]

[Operation] According to the above configuration, when the work equipment enters the interference danger area where it is likely to interfere with the operator's cab, the position of the solenoid valve is initially It switches to the position where the pressure oil to the pilot valve is lowered, and then switches at any time to the position where the pressure oil to the pilot valve is stopped. As a result, the spool of the work equipment control valve gradually returns to the neutral position without returning the work equipment control lever to the neutral position, so the flow of oil from the work equipment control valve to the work equipment hydraulic cylinder gradually stops, and the work equipment also gradually returns to the neutral position. Can be stopped.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention and its operation will be described with reference to FIGS. 1 to 6. First, a description will be given of the operation of a power shovel having a parallelogram-shaped work arm mechanism in which a part of the articulated work machine arm link mechanism that undergoes bending motion can be offset in the lateral direction.

FIG. 2 shows a plan view of the power shovel, and FIG.
indicates the same side. The power excavator has an upper rotating body 31 on top of a lower traveling body 30, and a driver's cab 3 in the upper rotating body 31.
2. The first boom 33 and the first boom hydraulic cylinder 34 are connected by a pin so that they can be raised and lowered. Note that the center Q of the first boom 33 and the first boom hydraulic cylinder 34 is located at a distance l away from the turning center P in an outward direction opposite to the operator's cab 32. The first boom 33 has a second boom 33a.
are connected by a pin so as to be able to swing in the left and right direction, and the second boom 3
3a has a third boom 35 and a third boom hydraulic cylinder 36.
are connected by a pin portion 37 so as to be swingable in the left-right direction. The third boom 35 includes an arm 39 and an arm hydraulic cylinder 4.
0 are connected by pins so that they can swing vertically. Further, a bucket 41 and a bucket hydraulic cylinder 42 are connected to the arm 39 with a pin so as to be swingable in the vertical direction.

The first boom is raised and lowered by the telescopic operation of the first boom hydraulic cylinder 34, and the arm hydraulic cylinder 4
The arm 39 is raised and lowered by the telescopic operation of the bucket hydraulic cylinder 42, and the bucket 41 is raised and lowered by the telescopic operation of the third boom hydraulic cylinder 36.
is offset horizontally.

By combining these operations, the working machine has a working area A as shown in FIG. In this working area A, the shaded area is an interference danger area (B) where there is a risk that the bucket 41 may interfere with the operator's cab 32, and a safety area (C) where there is no interference other than the interference danger area (B). Also, driver seat 3
FIG. 5 shows the interference danger area B when the maximum offset is made to the left with reference to 2.

The pilot valve 14 will be explained with reference to FIG. The pilot valve 14 is a work equipment control lever 15 that opens port P of the pilot hydraulic pump 1 and port P1 or P2 of the work equipment control valve 18 to supply pressure oil from the pilot hydraulic pump 1 according to the stroke of the work equipment control lever 15. , is supplied to the end face A or B of each spool of the working machine operating valve 18 to operate the spool.

[0013] As a result, each work machine reaches a speed corresponding to the stroke of the work machine control lever 15, and
When the pressure oil from the pilot hydraulic pump 1 stops, the spool of the work machine operating valve 18 returns to the neutral position by the spring on the end face of the spool, so the work machine stops.

Next, one embodiment of the present invention will be explained with reference to FIG. FIG. 1 is an explanatory diagram of the configuration of the hydraulic circuit of the work equipment interference prevention device. In the figure, 1 is a pilot hydraulic pump, and the pressure oil discharged by the pump is introduced into the input port 4a of the solenoid valve 4 through the pipe 3. be done. The solenoid valve 4 has three positions 5, 6, and 7 and four ports 4a, 4b, 4c, and 4d, and the positions are switched by a signal from the determining means 22. The port 4b of the solenoid valve 4 is connected to the pilot valve 14 through a pipe line 11, and the port 4d is connected to a pipe line 12 and is connected to a pressure regulating valve 13.
This is the circuit that passes through the tank and returns to the tank. Note that the pressure regulating valve 13 is set to operate at a lower pressure than the relief valve 2.

The operation of the pilot valve 14 is as described above and the details will be omitted, but the pilot valve 14 is connected to the work machine operation valve 18 through pipes 16 and 17, and the pressure oil of the pilot hydraulic pump 1 is connected to the work machine. It is supplied to the end face of each spool of the operation valve 18. The work machine operation valve 18 introduces pressure oil from a work machine hydraulic pump 29 into the hydraulic cylinder 21 through a pipe 19 or 20, and causes the hydraulic cylinder 21 to perform an expansion and contraction operation.

When the working machine is in the safety range C, the solenoid valve 4 is at position 5 because there is no signal from the determining means 22. For this reason, the pressure oil discharged from the pilot hydraulic pump 1 is introduced into the pilot valve 14 from the entire input port 4a, and is introduced into the pipe line 16 by operating the work equipment control lever 15.
Alternatively, the internal spool of the working machine operation valve 18 is fully opened through 17. As a result, pressure oil from the work equipment hydraulic pump 29 is introduced into the hydraulic cylinder 21 through the pipe 19 or 20, and the hydraulic cylinder 21 is expanded and contracted at a speed corresponding to the fully opened oil amount.

When the working machine enters the interference danger zone B, first a signal from the determining means 22 flows to the terminal 8, so that the position of the solenoid valve 4 is switched from position 5 to position 6. Therefore, the pressure oil discharged from the pilot hydraulic pump 1 is 1
One is introduced into the pilot valve 14 from the input port 4a,
The other one passes through the pipe line 12 from the port 4d to the pressure regulating valve 13.
The pressure is regulated and returned to the tank. As a result, the pressure oil discharged from the pilot hydraulic pump 1 and introduced into the pilot valve 14 is regulated by the pressure regulating valve 13, and the hydraulic pressure becomes lower than when the work machine is in the safety range C, so the work machine control lever 1
5, the internal spool of the working machine operating valve 18 opens in accordance with the low oil pressure. As a result, the amount of oil flowing from the working machine hydraulic pump 29 to the hydraulic cylinder 21 decreases, so that the speed of expansion and contraction of the hydraulic cylinder 21 becomes slower than when the working machine is in the safety range C.

Subsequently, the signal from the determining means 22 also flows to the terminal 9, so that the position of the solenoid valve 4 is switched from position 6 to position 7. Therefore, the entire amount of pressure oil discharged from the pilot hydraulic pump 1 returns to the tank from the input port 4a to the port 4d and through the pipe line 12, so no pressure oil from the pilot hydraulic pump 1 is introduced into the pilot valve 14. . Therefore, even if the work equipment control lever 15 is operated, pressure oil cannot be supplied to the end face of the internal spool of the work equipment control valve 18, so the internal spool returns to the neutral position.
Pressure oil from the work equipment hydraulic pump 29 to the hydraulic cylinder 21 also stops.

By the above-described operation, when the working machine enters the interference danger area B, the working machine connected to each hydraulic cylinder can gradually reduce its speed and stop.

Although not shown as another embodiment, an orifice in which the conduit 12 is constricted to increase the drain resistance may be used in place of the pressure regulating valve 13, or a variable orifice may be used in which the shock at stop can be arbitrarily changed.

[0021]

As explained above, the hydraulic circuit of the work machine interference prevention device of the present invention includes a solenoid valve upstream of the pilot valve for operating the work machine operation valve, and the solenoid valve The position of the pilot valve is gradually switched in response to a signal from the judgment means that determines whether the engine has entered the interference danger zone where interference is likely to occur, and the pressure oil to the pilot valve is gradually stopped. The work equipment can be stopped gradually regardless of the Therefore, it is possible to reduce the shock to the vehicle body, thereby preventing the driver from feeling uncomfortable and from spilling cargo such as earth and sand in the bucket.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the configuration of a hydraulic circuit of a work machine interference prevention device according to the present invention.

FIG. 2 is a plan view of the power shovel.

FIG. 3 is a side view of the power shovel.

FIG. 4 is an explanatory diagram of a safety area and an interference risk area of a working machine.

FIG. 5 is an explanatory diagram of the safety range and interference danger range of the working machine at the time of maximum left offset.

FIG. 6 is an explanatory diagram with a sectional view of the pilot valve.

FIG. 7 is a diagram illustrating the configuration of a conventional work machine interference prevention device.

[Explanation of symbols]

1 Pilot hydraulic pump 4 Solenoid valve 14 Pilot valve 15 Work equipment control lever 18 Work equipment operation valve 21 Hydraulic cylinder 29 Work equipment pump 32 Driver's cabin

Claims (2)

[Claims] Claim 1: When a working machine operated by a hydraulic actuator enters an interference danger area where it is likely to interfere with the operator's cab, the work equipment is stopped by a signal from a judgment means that determines that it has entered the interference danger area. In the work equipment interference prevention device, a solenoid valve is provided upstream of a pilot valve for operating the work equipment operating valve, and the position of the solenoid valve is gradually switched in response to a signal from the determining means to control the pressure to the pilot valve. A hydraulic circuit for a work machine interference prevention device that features a configuration that gradually stops oil. 2. The hydraulic circuit of the work machine interference prevention device according to claim 1, wherein even if the work machine operating lever is in the work machine operating position, the spool of the work machine operating valve returns to the neutral position and the work machine stops. .