JP2002121772A - Control method for work machine, and control device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent malfunction of a work machine when abnormality is generated in hydraulic equipment or the like. SOLUTION: An electric joy stick 12 operates control valves 3 and 4 by actuation command signals, and the control valves 3 and 4 control hydraulic actuators 7 and 8 of the work machine. Pressure as result of valve actuation outputted by result of actuation of the control valves 3 and 4 is detected by a pressure detector 15. When the electric joy stick 12 is at a neutral position, and as an engine key switch 28 to start or stop a prime mover 1 to drive a hydraulic control system is on, a controller 13a forcedly stops output of signals to actuate the control valves 3 and 4 in the condition of pressure abnormality where pressure as result of valve actuation is higher than a set pressure. The controller 13a can output the signals to actuate the control valves 3 and 4 as the condition of the pressure abnormality is eliminated, and when a recognition switch 14a is operated at least once.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for a working machine equipped with a hydraulic control system and a control device therefor.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show a conventional example.

FIG. 5 shows an example of a load sensing hydraulic system mounted on a working machine such as a hydraulic excavator. In FIG. 5, reference numeral 1 denotes a prime mover mounted on the working machine, which is driven by the prime mover 1. The variable displacement hydraulic pump 2 includes a swash plate control mechanism 2a for controlling a pump discharge flow rate. The discharge ports of the hydraulic pump 2 are connected to inlet ports of control valves 3 and 4 for switching the direction of the pressure oil supplied from the hydraulic pump 2.

[0004] The outlet ports of the control valves 3 and 4 have pressure compensating valves 5a and 5a for keeping the pressure drop of the control valves 3 and 4, ie, the differential pressure between the inlet and the outlet of the control valves 3 and 4 constant. Hydraulic actuators (hydraulic cylinders) 7, 8 are connected via 5b, 6a, 6b.

[0005] From the hydraulic pump 2 to the control valve 3,
An unload valve 9 for releasing pressurized oil discharged from the hydraulic pump 2 to the tank 11 when the control valves 3 and 4 are in the neutral position is connected to a pipeline leading to the inlet port 4.

An inlet of a shuttle valve 10 for selecting a high pressure side of the load pressure guided from the two control valves 3 and 4 is connected to ports in the center of the two control valves 3 and 4 in the drawing via pipes L1 and L2. Have been. This shuttle valve
The inlet of 10 is connected to the tank 11 at the neutral position of the control valves 3 and 4.

The outlet of the shuttle valve 10 is connected to the swash plate control mechanism 2a of the hydraulic pump 2, the pressure compensating valve 5a,
5b, 6a, 6b and the respective pilot operation sections of the unload valve 9 are communicated.

[0008] The swash plate control mechanism 2a is provided with a force based on the discharge pressure of the hydraulic pump 2 and a load pressure (high pressure side) selected by the shuttle valve 10 out of the load side operating hydraulic pressure guided from the control valves 3 and 4. Hereinafter, this load pressure is referred to as “load sensing pressure”) and a control valve 2a1 that controls so that the sum of the force by the spring and the force set by the spring is balanced.
An actuator 2a2 which is operated by the pressure oil passing through the control valve 2a1 to control the tilt angle of the swash plate of the hydraulic pump 2.

An electric joystick 12 as an operating device operated by an operator is connected to an input side of a controller 13 for performing a control operation based on a signal of the electric joystick 12, and an output side of the controller 13 is connected to a control valve. Electro-oil conversion valves 3a, 3 mounted on 3, 4
b, 4a, and 4b.

The control valves 3 and 4 are driven by the electro-hydraulic conversion valves 3a, 3b, 4a and 4b,
Directional control and flow rate control of the hydraulic oil supplied to the hydraulic actuators 7 and 8 of the working machine from.

An input side of the controller 13 is connected to a hydraulic lock switch 14 for locking or unlocking the hydraulic system by an operator's manual on / off operation.

FIG. 6 shows a control block diagram of a conventional controller 13. In FIG. 6, the electric joystick 12 is connected to function generators 22a and 22b for setting command signals for the respective electro-hydraulic conversion valves 3a and 3b based on an operation command signal input from the electric joystick 12. , These function generators 22a, 22b are function generators
The switches 23a and 23b are connected to switches 23a and 23b for turning on and off the command signals output from the switches 22a and 22b, respectively. These switches 23a and 23b are drivers for driving the electro-oil conversion valves 3a and 3b.
24a and 24b, respectively.

The switches 23a and 23b open between the function generators 22a and 22b and the drivers 24a and 24b when the hydraulic lock switch 14 is turned on, and when the hydraulic lock switch 14 is turned off. , Function generators 22a, 22
b and the drivers 24a and 24b.

Although not shown in FIG. 6, the electro-hydraulic conversion valves 4a and 4b have the same control blocks as described above.

In the above-mentioned electronically controlled load sensing hydraulic system, when the hydraulic lock switch 14 is turned off, the switches 23a and 23b are connected. When the electric joystick 12 is operated in this state, the command signals of the electro-oil conversion valves 3a and 3b are set by the function generators 22a and 22b in the controller 13, and the electro-oil conversion valves 3a and 3b are driven by the drivers 24a and 24b. , The control valve 3 is controlled.

When hydraulic oil is supplied to the hydraulic actuators 7 and 8, pipes L 1 and L 1 are supplied from the control valves 3 and 4.
Each load sensing pressure passing through L2 is led to the shuttle valve 10, the load sensing pressure on the high pressure side is selected by the shuttle valve 10, and the control valve 2a1 of the swash plate control mechanism 2a of the hydraulic pump 2 via the pipe L3, the pressure compensation It is guided to valves 5a, 5b, 6a, 6b and unload valve 9. As a result, the pressure of the hydraulic pump 2 is set to a pressure higher than the load sensing pressure selected by the shuttle valve 10 by a specified pressure.

The pressure difference between the inlet and outlet of the control valves 3 and 4 is kept constant by the pressure compensating valves 5a, 5b, 6a and 6b, and the pump flow rate proportional to the opening area of the control valves 3 and 4 is controlled by the hydraulic pressure. It is distributed to actuators 7 and 8.

[0018]

In such a conventional hydraulic system, when an abnormality occurs in a hydraulic device or the like, there is a problem that the hydraulic actuators 7 and 8 start to operate even when the electric joystick 12 is in the neutral position. .

The present invention has been made in view of the above points, and has as its object to prevent a malfunction of a working machine even when an abnormality occurs in a hydraulic device or the like.

[0020]

According to a first aspect of the present invention, there is provided a method of controlling a working machine, wherein a control valve in a hydraulic control system of a working machine having a hydraulic actuator is controlled by a signal output from an operating device. In the above, when the operating device is in the neutral position and the engine key switch for starting or stopping the engine that drives the hydraulic control system is in the ON state, the valve operation result pressure generated as a result of operating the control valve is higher than the set pressure. This is a control method of the work equipment that forcibly stops the output of the signal that activates the control valve in the state of abnormal pressure, so that the state of abnormal pressure due to failure of the operating device or hydraulic equipment of the hydraulic control system can be reduced. If this occurs, the operation of the control valve is forcibly stopped, and the control valve Since blocking the aggressive media supply, it is possible to prevent the operating working machine erroneous. At that time, when the engine key switch is in the ON state, the condition of the pressure abnormality is set, and when the engine key switch is in the OFF state, the control valve can be switched, so that the engine is stopped for repair work or the like. By operating the operating device to switch the control valve, the pressure sealed in the hydraulic actuator can be released.

According to a second aspect of the present invention, in the method for controlling a work machine according to the first aspect, the control valve is actuated by eliminating the abnormal pressure state and operating the confirmation switch at least once. This is a method of controlling the signal to be output so that the operator can operate the confirmation switch after the condition of the abnormal pressure is eliminated, and the operator is forced to change the normal state. Confirmation and malfunction can be reliably prevented.

According to a third aspect of the present invention, there is provided an operation device which is manually operated, a control valve in a hydraulic control system which can be operated by an operation command signal output from the operation device, and a control valve which is controlled by the control valve. A hydraulic actuator that drives the movable part of the work machine, an engine key switch that starts or stops the engine that drives the hydraulic control system, and a valve operation result pressure that detects the valve operation result pressure that is output based on the operation result of the control valve When the control unit and the operation unit are in the neutral position and the engine key switch is in the ON state, and the valve operation results in a pressure abnormality in which the pressure becomes higher than the set pressure, the output of the signal to operate the control valve is forcibly applied. A control device for a working machine, comprising a controller for stopping the operation of the working machine. The controller controls the control valve so that it cannot be operated by the operating device, forcibly stops the output to the control valve, and shuts off the supply of hydraulic oil from the control valve to the hydraulic actuator. The possibility of operation can be reliably prevented. At that time, when the engine key switch was in the ON state, the condition of the pressure abnormality was considered as an abnormal condition. Therefore, when the engine was stopped for repair work, etc., the operating device was operated to switch the control valve, and the hydraulic actuator was operated. Pressure can be released.

According to a fourth aspect of the present invention, in the control device for a working machine according to the third aspect, the operating device is an electric joystick that outputs an operation command signal to the control valve as an electric signal. It has built-in switching means for switching between a state in which the control valve can be operated and a state in which the control valve cannot be operated by interrupting the operation command signal from the control valve to the control valve. In the work equipment that controls the operation, even if a pressure abnormality occurs due to a failure of the operating device or the hydraulic equipment of the hydraulic control system, the operation of the control valve is forcibly stopped, and the hydraulic oil from the control valve to the hydraulic actuator is Since the supply is cut off, malfunction of the working machine can be prevented.

According to a fifth aspect of the present invention, in the control device for a working machine according to the third aspect, the operating device is a pilot operating valve for pilot-operating the control valve with a pilot pressure. In the working machine that controls the hydraulic system with a pilot-controlled control valve, a switching unit that switches between a state in which the pilot source pressure can be supplied and a state in which the pilot source pressure cannot be supplied is interposed. Even if a pressure abnormality occurs due to a failure of the actuator or hydraulic equipment of the hydraulic control system, the switching means shuts off the pilot source pressure and forcibly stops the operation of the control valve. By shutting off the supply of hydraulic oil to the actuator, malfunction of the working machine can be prevented.

According to a sixth aspect of the present invention, a valve operation result pressure detector in the control device for a working machine according to any one of the third to fifth aspects detects a load sensing pressure on the load side of the control valve. This is a pressure detector, whereby it is possible to easily determine whether or not the control valve is at the neutral position where the supply of the hydraulic oil is stopped by only detecting the load sensing pressure with the pressure detector.

According to a seventh aspect of the present invention, in the control device for a working machine according to any one of the third to sixth aspects, a confirmation switch which is manually operated is provided, and the controller comprises:
An operation signal generator for outputting 1 at the neutral position and near the neutral position and outputting 0 at other operation positions, and an ON signal for delaying an ON signal output from the operation signal function generator A delay circuit, an operation result generator for outputting 1 when the valve operation result pressure is higher than a predetermined set pressure, and outputting 0 when the valve operation result pressure is low, an on-delay circuit of the operation signal function generator, an engine key switch And an AND operator for calculating the AND of each output of the operation result function generator; and, based on the output of the AND operator, the operating device is at the neutral position, and the engine key switch is on. In the event of a pressure abnormality where the valve operation result pressure becomes higher than the set pressure, the output of the signal to operate the control valve is forcibly stopped, and the pressure abnormality is released. And a flip-flop arithmetic unit for controlling the output of a signal for operating the control valve by operating the confirmation switch at least once, whereby a function generator for the operation signal is turned on. The controller can be easily formed by a simple logic operation circuit equipped with a delay circuit, a function generator for operation results, an AND operation unit, and a flip-flop operation unit, and all the operation units are set in a neutral state by the on-delay circuit. After that, the pressure diagnosis can be reliably performed after the elapse of the set time. In addition, since the condition for restarting the operation is that the operator operates the confirmation switch after the state of the abnormal pressure is eliminated, the operator is forcibly checked for the normal state, and malfunction can be reliably prevented.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to FIGS.
3 and FIG. 4 and another embodiment shown in FIG. 4. The same parts as those in the conventional example shown in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, the basic load sensing circuit of the electronically controlled load sensing hydraulic system according to the present invention has the same configuration as that of the prior art shown in FIG. A pressure detector 15 as a valve operation result pressure detector for detecting a load sensing pressure as a valve operation result pressure output according to an operation result of the control valves 3 and 4 is provided on a pipe L3 connected to an outlet of the shuttle valve 10. In addition, this pressure detector 15 is connected to the input side of the controller 13a described below.

On the input side of the controller 13a, in addition to the pressure detector 15, an electric joystick 12 as an operating device for manually outputting an operation command signal by an operator.
And an engine key switch 28 for starting or stopping the prime mover 1, that is, an engine mounted on a working machine such as a hydraulic shovel, and a confirmation switch 14a.
The confirmation switch 14a uses a hydraulic lock switch.

The output side of the controller 13a is connected to electro-hydraulic conversion valves 3a, 3b, 4a and 4b mounted on the control valves 3 and 4 as in the conventional example.

In FIG. 1, an electric joystick
12 to the control valve 3 via the controller 13a
The electric system from the electro-hydraulic conversion valves 3a, 3b, 4a, and 4b of FIG.
The hydraulic system that reaches the hydraulic actuators (hydraulic cylinders) 7 and 8 via the pressure compensation valve 5 and the pressure compensating valves 5a, 5b, 6a and 6b is a hydraulic control system.

FIG. 2 is a control arithmetic block diagram of the controller 13a. As shown in FIG. 2, a function generator 22a that sets a command signal for the electro-hydraulic conversion valves 3a and 3b at an output portion of the electric joystick 12 based on the operation command signal.
, 22b are connected and these function generators 22a, 22b
The switches 23a and 23b as switching means for transmitting or interrupting the command signals output from the function generators 22a and 22b by on / off operation are connected to these switches. Each of the switches 23a and 23b is connected to each of the switches. The point that the drivers 24a and 24b for driving the oil conversion valves 3a and 3b are connected is the same as in the conventional example.

Further, a function for generating an operation signal for generating an ON signal "1" or an OFF signal "0" according to the magnitude of the operation command signal output from the electric joystick 12 is provided at the output portion of the electric joystick 12. The input part of the device 25 is connected, and the output part of the operation signal function generator 25 is connected to the on-delay circuit 26.

The on-delay circuit 26 is for starting a pressure diagnosis after a lapse of a set time after all the electric joysticks 12 are in a neutral state.

The output signal of the pressure detector 15 for detecting the load sensing pressure is supplied with an ON signal "1" according to the magnitude of the load sensing pressure signal as the valve operation result pressure output from the pressure detector 15. Alternatively, the input of the operation result function generator 27 for generating the off signal “0” is connected.

Further, these operation signal function generators 25
On-delay circuit 26 and function generator 27 for operation results
The engine key switch 28 is connected to an input of an AND operator 29 (hereinafter, this AND operator is referred to as an "AND operator") for calculating the AND of the output signals. Have been.

A DQ type flip-flop operation is applied to the output of the AND operation unit 29 via a NOT operation unit 31 for inverting the output signal (hereinafter, this NOT operation unit is referred to as a "NOT operation unit"). The reset input terminal CLR of the device 32 is connected. The output of the confirmation switch 14a is connected to the clock input terminal CLK of the flip-flop operation unit 32, and "1" is always connected to the data input terminal D.

An output terminal for outputting a signal obtained by inverting the output signal from the output terminal Q of the flip-flop operation unit 32 /
Q is connected to the contact drive units of the switches 23a and 23b, respectively.

The DQ type flip-flop operation unit 32 comprises:
When the output signal from the NOT operator 31 is "0", the reset input terminal CLR is in a reset state, so that the output signal of the output terminal Q is "0" and the output signal of the output terminal / Q is "1". Becomes In this reset state, the confirmation switch
Even if the rising edge of the clock pulse is input to the clock input terminal CLK from 14a, the output signal of the output terminal Q remains "0" and the output signal of the output terminal / Q remains "1".

Further, when the output signal from the NOT operator 31 is "1", the reset input terminal CLR is in a non-reset state. Therefore, when the rising edge of the clock pulse enters the clock input terminal CLK, the data input terminal CLR is reset. The input signal “1” to D is copied and “1” is output from the output terminal Q, and an inverted “0” is output from the output terminal / Q,
This state is continued.

Although FIG. 2 shows a block diagram of the control operation for the control valve 3, the control valve 4 also has a similar control operation block.

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described.

(1) Abnormal pressure When the engine key switch 28 is ON, the load sensing pressure detected by the pressure detector 15 is a predetermined value even when all the electric joysticks 12 are in the neutral position. In the state of a pressure abnormality higher than the set pressure, the output from the on-delay circuit 26, the output from the operation result function generator 27 and the output from the engine key switch 28 all become "1", and the AND operator 29 Becomes "1", the output of the NOT operator 31 becomes "0", and a reset signal is input to the reset input terminal CLR of the flip-flop operator 32, so that the output signal of the output terminal Q is reset. And the output signal of the output terminal / Q becomes "1", the contacts of the switches 23a and 23b are turned off, and the output from the function generators 22a and 22b to the drivers 24a and 24b can be stopped. With a lock execution state can hold the lock execution state. Thereby, the control valves 3 and 4
Is maintained at the neutral position, and malfunction of the hydraulic actuators 7, 8 can be prevented.

(2) Confirmation switch 14a when pressure is abnormal
Is turned on. In this state of abnormal pressure, since a reset signal is input to the reset input terminal CLR of the flip-flop operation unit 32, the operator turns on the confirmation switch 14a and turns the clock input terminal CLK to Even if the rising edge of the clock pulse is input, the output signal of the output terminal Q remains “0”, the output signal of the output terminal / Q remains “1”, and the lock execution state is maintained. it can.

(3) When the pressure abnormality is eliminated Further, when all the electric joysticks 12 are in the neutral position, the load sensing pressure detected by the pressure detector 15 becomes lower than a predetermined set pressure, and When the state is resolved and the state becomes normal, the output of the AND operator 29 becomes “0”, the output of the NOT operator 31 becomes “1”,
Although no reset signal is present at the reset input terminal CLR of the flip-flop operation unit 32, the locked state is maintained even if the abnormal pressure is eliminated, the output signal of the output terminal Q is "0", and the output terminal / Q Output signal is "1", switch
The contacts of 23a and 23b remain off, and the drivers 24a and
Output to 24b is stopped.

(4) When the confirmation switch 14a is turned on in a state in which the pressure abnormality has been resolved. In a state in which the pressure abnormality has been resolved, the operator turns on the confirmation switch 14a, and the clock is input to the clock input terminal CLK. When the rising edge of the pulse enters, the input signal "1" to the data input terminal D is copied and "1" is output from the output terminal Q, and the output signal of the output terminal / Q becomes "0". The contacts of the devices 23a and 23b are turned on, and the locks are released and output to the drivers 24a and 24b is enabled, and the unlocked state can be maintained.

(5) When the electric joystick 12 is operated in the unlocked state When the electric joystick 12 is operated in the unlocked state, the function generators 22a and 22b corresponding to the lever operation amount are operated.
Is transmitted to the driver 24a through the switches 23a and 23b.
, 24b, the control valve 3 is controlled via the electro-hydraulic conversion valves 3a, 3b, and the hydraulic actuator 7 is driven.

As described above, the DQ flip-flop operation unit 32 holds the lock execution state once the abnormal pressure state is detected, and keeps the lock executed state even if the abnormal pressure state is resolved. Holding, on the other hand, after the state of abnormal pressure is resolved, the confirmation switch 14a is turned on at least once to obtain the unlocked state, so that the operator is forced to confirm the normal state. It is.

(6) When the engine is stopped and repair work is performed, “when the engine key switch 28 is on”
The condition of the abnormal pressure condition was that the control valves 3 and 4 were not used when the engine key switch 28 was not in the ON state.
Is to be able to perform a switching operation.

That is, when the hydraulic lock is applied when the pressure of the load circuit is high, the pressure is sealed in the hydraulic actuators 7 and 8 by the control valves 3 and 4 in the neutral position even when the engine is stopped. When the pressure abnormal state is determined only by the outputs of the signal function generator 25 and the on-delay circuit 26 and the output of the operation result function generator 27, the reset input terminal of the flip-flop calculator 32 is always determined.
Since the CLR is reset and the contacts of the switches 23a and 23b are turned off and the output to the drivers 24a and 24b is stopped, the control valves 3 and 4 cannot be switched. It is not possible to answer the need to release the pressure in the hydraulic actuators 7 and 8 after the engine is stopped and before the repair work.

Therefore, when the engine key switch 28 is in the off state, it is assumed that the abnormal pressure state has been resolved and
The output of the AND operator 29 is "0", the output of the NOT operator 31 is "1", and the reset input terminal CLR of the flip-flop operator 32 is in a non-reset state, and the confirmation switch 14a is turned on for confirmation. With this, the contacts of the switches 23a and 23b are turned on for unlocking, and the drivers 24a and 24b
By operating the electric joystick 12 to switch the control valves 3 and 4 to the non-neutral position, the pressure held in the hydraulic actuators 7 and 8 can be released to the tank 11.

Next, another embodiment according to the present invention will be described with reference to FIGS.

In FIG. 3, the hydraulic control systems such as the hydraulic pump 2, the control valves 3, 4 and the hydraulic actuators 7, 8 are the same as those shown in FIG. Is omitted.

On the other hand, a pilot operation system for pilot-operating the control valves 3 and 4 comprises the following elements.

In place of the electric joystick 12, a pilot operated valve (hereinafter referred to as a "remote control valve") as an operating device for pilot-operating the control valve 3 by operating a lever by an operator of a working machine.
41a, 41b) and a pilot control valve (hereinafter, this pilot control valve is referred to as "remote control valves 42a, 42b") as an operating device for pilot-operating the control valve 4 by lever operation. ing.

These remote control valves 41a, 41b, 42a, 42
b designates the hydraulic pressure directly supplied from the pilot hydraulic pressure source 43 as the pilot source pressure, that is, the pilot primary pressure, and the pilot pressure acting portions 3A, 3B, 4A, 4B of the control valves 3, 4.
Is controlled to reduce the secondary pressure of the pilot as an operation command signal supplied to the controller according to the lever operation amount.

From the pilot hydraulic pressure source 43, the remote control valves 41a,
In the pilot source pressure supply line 43a for supplying the pilot source pressure to 41b, 42a, 42b, this line 43a is communicated or cut off, and the pilot source supplied to each remote control valve 41a, 41b, 42a, 42b is connected. An electromagnetic switching valve 44 as switching means for controlling the pressure on / off is interposed. This electromagnetic switching valve
The 44 solenoid 44a is connected to the output of the controller 13b.

The solenoid-operated switching valve 44 has its solenoid 44a
When the solenoid 44a is excited by the supply of the ON signal "1" to the solenoid 44a, the pilot source pressure supply line 43a is communicated. When the solenoid 44a is returned by the spring 44b with the OFF signal "0" to the solenoid 44a, the pilot 44 Main pressure supply line
Block 43a.

Further, an inlet of the first shuttle valve 45a is connected between the pilot secondary pressure lines of the remote control valves 41a and 41b, and similarly, a second shuttle valve 45a is connected between the pilot secondary pressure lines of the remote control valves 42a and 42b. The inlet of the second shuttle valve 45b is connected, and the inlet of the third shuttle valve 45c is connected between the outlets of these shuttle valves 45a and 45b.
A pressure detector 46 is connected to the outlet of 45c, and the pressure detector 46 is connected to an input of the controller 13b.

In short, the shuttle valves 45a, 45b, 45c
Selects the highest pressure among the pilot secondary pressures as operation command signals output from the remote control valves 41a, 41b, 42a, 42b, and the pressure detector 46 provided at the output port of the final shuttle valve 45c , Remote control valves 41a, 41b, 42a, 42
The maximum pressure (remote control pressure) output from b is detected.

On the input side of the controller 13b, together with the pressure detector 46, a confirmation switch 14a, a pressure detector 15 as a valve operation result pressure detector for detecting a load sensing pressure as a valve operation result pressure, and an engine The key switch 28 is connected to the solenoid switch 44a, and the output side of the controller 13b is connected to the solenoid 44a of the electromagnetic switching valve 44.
It is connected to the.

In FIG. 3, the pilot system from the pilot hydraulic pressure source 43 to the pilot pressure action sections 3A, 3B, 4A, 4B of the control valves 3, 4 via the remote control valves 41a, 41b, 42a, 42b is defined as an operation system. Further, the control valves 3 and 4 and the pressure compensating valves 5a, 5b,
A hydraulic system that reaches the hydraulic actuators 7 and 8 via 6a and 6b is referred to as a hydraulic control system.

FIG. 4 shows a control block of the controller 13b. The configuration of the controller 13b is the same as that of the controller 13a shown in FIG.
5. On-delay circuit 26, function generator 27 for operation result, A
It has an ND operator 29, a NOT operator 31, and a DQ type flip-flop operator 32. The output of the confirmation switch 14a is connected to the clock input terminal CLK of the flip-flop operator 32, and the data input terminal “1” is always connected to D.

On the other hand, the input of the operation signal function generator 25 of the controller 13b is connected to the output of the pressure detector 46 for detecting the remote control pressure, and the output of the flip-flop calculator 32. Q includes the electromagnetic switching valve 44
Is connected to the solenoid 44a.

Next, the operation of the embodiment shown in FIGS. 3 and 4 will be described.

(1a) Abnormal pressure When the engine key switch 28 is ON, the pressure is detected by the pressure detector 15 even though all the remote control valves 41a, 41b, 42a, 42b are in the neutral position. In the case of a pressure abnormality in which the load sensing pressure becomes higher than the predetermined set pressure, the output from the on-delay circuit 26, the output from the operation result function generator 27, and the output from the engine key switch 28 all become "1". The output of the AND operator 29 becomes “1”, the output of the NOT operator 31 becomes “0”,
Since the reset signal is input to the reset input terminal CLR of the flip-flop operation unit 32, the output signal of the output terminal Q is reset to "0", and the electromagnetic switching valve 44 turns off the signal "0" to the solenoid 44a. With the return operation by the spring 44b, the pilot source pressure supply line 43
The lock execution state is established in which a is shut off, and this lock execution state can be maintained. Thereby, the remote control valve 41a
, 41b, 42a and 42b malfunction, no pilot pressure is generated from them, so that the pilot-operated control valves 3 and 4 can be kept at the neutral position and malfunction of the hydraulic actuators 7 and 8 can be prevented. .

(2a) Confirmation switch 14a when pressure is abnormal
Is turned on. In this state of abnormal pressure, since a reset signal is input to the reset input terminal CLR of the flip-flop operation unit 32, the operator turns on the confirmation switch 14a and turns the clock input terminal CLK to Even if the rising edge of the clock pulse is input, the state of the output signal of the output terminal Q remains “0”, and the lock execution state can be maintained.

(3a) When the pressure abnormality is eliminated When all the remote control valves 41a, 41b, 42a, and 42b are in the neutral position, the load sensing pressure detected by the pressure detector 15 becomes lower than a predetermined set pressure. When the pressure becomes low and the abnormal pressure state is resolved and the state becomes normal, the AND operator 29
Becomes "0" and the output of the NOT operator 31 becomes "1".
And the reset input terminal of the flip-flop operator 32
Although the reset signal disappears from the CLR, the locked state is maintained even if the abnormal pressure condition is resolved, and the output terminal Q
Is maintained at "0", and the lock execution state of shutting off the pilot source pressure supply line 43a by the electromagnetic switching valve 44 can be maintained.

(4a) When the confirmation switch 14a is turned on while the pressure abnormality has been eliminated. In a state where the pressure abnormality has been eliminated, the operator turns on the confirmation switch 14a to apply a clock to the clock input terminal CLK. When the rising edge of the pulse enters, the input signal “1” to the data input terminal D is copied and “1” is output from the output terminal Q, so that the solenoid 44 of the electromagnetic switching valve 44
By energizing a, the pilot source pressure supply pipe 43a is communicated, and the lock state is released, and the lock release state can be maintained.

(5a) In the unlocked state, the remote control valve 41a,
When the remote control valves 41a, 41b, 42a and 42b are operated in the unlocked state when the remote control valves 41a, 42a and 42b are operated.
Pilot pressure action parts 3A, 3 of control valves 3, 4
Acting on B, 4A and 4B, the displacement direction and displacement of control valves 3 and 4 are controlled, and hydraulic actuator 7
Is driven.

As described above, the DQ type flip-flop operation unit 32 holds the lock execution state once the abnormal pressure state is detected, and continues the lock executed state even if the abnormal pressure state is eliminated. Holding, on the other hand, after the state of abnormal pressure is resolved, the confirmation switch 14a is turned on at least once to obtain the unlocked state, so that the operator is forced to confirm the normal state. It is.

(6a) When the engine is stopped to perform repair work “When the engine key switch 28 is on”,
Since the condition of the pressure abnormality is set, the pressure in the hydraulic actuators 7 and 8 can be released after the engine is stopped and before the repair work is performed as in (6).

[0073]

According to the first aspect of the present invention, when a pressure abnormality occurs due to a failure of an operating device or a hydraulic device of a hydraulic control system, the operation of the control valve is forcibly stopped, and the control is stopped. Since the supply of the hydraulic oil from the valve to the hydraulic actuator is shut off, malfunction of the work machine can be prevented. At that time, when the engine key switch is in the on state, the pressure is abnormal, so when the engine key switch is in the off state, the control valve can be switched, so that the engine is stopped for repair work etc. By operating the operating device to switch the control valve, the pressure sealed in the hydraulic actuator can be released.

According to the second aspect of the present invention, the condition for restarting the operation is to make the operator operate the confirmation switch after the abnormal pressure state is resolved, so that the operator is forcibly confirmed the normal state. , Malfunction can be reliably prevented.

According to the third aspect of the present invention, when the pressure is abnormal, the controller controls the operation valve so that the control valve cannot be operated, and forcibly stops the output to the control valve. Since the supply of the hydraulic oil to the hydraulic actuator is interrupted, the possibility that the work machine malfunctions can be reliably prevented. At that time, when the engine key switch was in the ON state, the condition of the pressure abnormality was considered as an abnormal condition. Therefore, when the engine was stopped for repair work, etc., the operating device was operated to switch the control valve, and the hydraulic actuator was operated. Pressure can be released.

According to the fourth aspect of the present invention, in a working machine that controls a hydraulic system by an electronically controlled control valve, a state of abnormal pressure due to a failure of an operating device or a hydraulic device of a hydraulic control system occurs. However, since the operation command signal from the operating device to the control valve is cut off by the switching means of the controller, the operation of the control valve is forcibly stopped, and the supply of hydraulic oil from the control valve to the hydraulic actuator is cut off. Can be prevented from malfunctioning.

According to the fifth aspect of the present invention, in a working machine that controls a hydraulic system with a pilot-controlled control valve, when an abnormal pressure state occurs due to a failure of an operating device or a hydraulic device of a hydraulic control system. However, since the pilot source pressure is cut off by the switching means and the operation of the control valve is forcibly stopped, the supply of hydraulic oil from the control valve to the hydraulic actuator is cut off,
The work machine can be prevented from malfunctioning.

According to the present invention, it is possible to easily determine whether or not the control valve is at the neutral position where the supply of the hydraulic oil is stopped by merely detecting the load sensing pressure with the pressure detector.

According to the seventh aspect of the present invention, a controller is provided by a simple logical operation circuit including an operation signal function generator, an on-delay circuit, an operation result function generator, an AND operator, and a flip-flop operator. Can be easily formed, and the on-delay circuit can reliably diagnose the pressure after a lapse of a set time after all the operating devices are in the neutral state. In addition, since the condition for restarting the operation is that the operator operates the confirmation switch after the state of the abnormal pressure is eliminated, the operator is forcibly checked for the normal state, and malfunction can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment in which a control device for a working machine according to the present invention is applied to an electronically controlled load sensing hydraulic system.

FIG. 2 is a block diagram showing a control calculation block of a controller in the control device of FIG. 1;

FIG. 3 is a circuit diagram showing an embodiment in which the control device for a working machine according to the present invention is applied to a pilot-operated load sensing hydraulic system.

FIG. 4 is a block diagram showing a control calculation block of a controller in the control device of FIG. 3;

FIG. 5 is a circuit diagram showing a conventional electronically controlled load sensing hydraulic system.

FIG. 6 is a block diagram showing a control operation block of a controller in a conventional system.

[Explanation of symbols]

3, 4 Control valve 7, 8 Hydraulic actuator 12 Electric joystick 13a, 13b as operating device Controller 14a Confirmation switch 15 Valve operation result Pressure sensor 23a, 23b as pressure detecting device Switching device as switching means 25 Operation signal function Generator 27 Function generator for operation result 28 Engine key switch 29 AND operator 32 Flip-flop operator 41a, 41b, 42a, 42b Pilot operated valve (remote control valve) as operating device 44 Electromagnetic switching valve as switching means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F15B 20/00 F15B 11/02 X (72) Inventor Nobuaki Matoba 2-5-1 Marunouchi, Chiyoda-ku, Tokyo No. F-term in Sanshi Heavy Industries Co., Ltd. (reference) JJ01

Claims (7)

[Claims] 1. A control method for a working machine, wherein a control valve in a hydraulic control system of a working machine having a hydraulic actuator is controlled by a signal output from the operating device, wherein the operating device is in a neutral position and the hydraulic control system When the engine key switch that starts or stops the engine that drives the engine is in the ON state, the valve operation result resulting from the operation of the control valve is higher than the set pressure. A work machine control method characterized by forcibly stopping output. 2. The work machine according to claim 1, wherein a signal for operating the control valve is output so that a signal for operating the control valve is output when the state of the pressure abnormality is eliminated and the confirmation switch is operated at least once. Control method. 3. An operation device which is manually operated, a control valve in a hydraulic control system which can be operated by an operation command signal output from the operation device, and a movable portion of the working machine controlled by the control valve. A hydraulic actuator, an engine key switch for starting or stopping an engine that drives a hydraulic control system, a valve operation result pressure detector for detecting a valve operation result pressure output based on an operation result of a control valve, and a neutral position of the actuator. And a controller for forcibly stopping the output of a signal for operating the control valve in a state of abnormal pressure in which the valve operation result pressure is higher than a set pressure when the engine key switch is in an on state. A work machine control device characterized by the above-mentioned. 4. The operation device is an electric joystick that outputs an operation command signal to the control valve as an electric signal, and the controller controls the control valve by the operation device by interrupting the operation command signal from the operation device to the control valve. 4. The control device for a working machine according to claim 3, further comprising a switching unit for switching between an operable state and an unoperable state. 5. An operation device, which is a pilot operation valve for pilot-operating a control valve with a pilot pressure, wherein a pipe for supplying a pilot source pressure to the pilot operation valve is provided.
4. A switching means for switching between a state in which the pilot source pressure is supplied and a state in which the pilot source pressure is not supplied.
The control device of the working machine according to the above. 6. The control of the working machine according to claim 3, wherein the valve operation result pressure detector is a pressure detector that detects a load sensing pressure on a load side of the control valve. apparatus. 7. An operation signal generator comprising a manually operated confirmation switch, wherein the controller outputs a 1 at a neutral position and near the neutral position and outputs a 0 at another operation position. An on-delay circuit for delaying the on signal output from the operation signal function generator; and an operation result function for outputting 1 when the valve operation result pressure is higher than a predetermined set pressure and outputting 0 when the valve operation result pressure is lower than a predetermined set pressure. A logical AND calculator for calculating the logical AND of the outputs of the operation signal function generator, the engine key switch, and the operation result function generator; and , When the actuator is in the neutral position and the engine key switch is on,
In the event of a pressure abnormality in which the valve operation results in a pressure higher than the set pressure, the output of the signal that activates the control valve is forcibly stopped, the pressure abnormality is eliminated, and the confirmation switch is operated at least once. The control device for a working machine according to any one of claims 3 to 6, further comprising: a flip-flop arithmetic unit for controlling a signal for operating the control valve to be output.