JPH02168004A - Device for method for detecting hydraulic circuit failure - Google Patents

Abstract

PURPOSE:To learn a failure portion without interrupting work by providing pressure sensors and flow detectors at the respective portions of hydraulic circuits to compare preset values with detected values by a control device for specifying the failure portion which is displayed in a failure display device. CONSTITUTION:A pressure sensor 2 is provided in the discharge pipe path 1 of a variable capacity pump 16, a pressure sensor 4 in the operation circuit 3 of a two-stage relief valve 7, a pressure sensor 6 in the operation circuit 5 of a cutoff valve 20 and a flow detector 9 in the return circuit 8 of the two- stage relier valve 7, respectively. The respective sensors and detectors have set values in advance. Whether detected values are higher than preset values or not and at this time an excavation power-up function button 14 and a run operation lever(not shown in Fig.) are in either ON or OFF state, are judged by a control device 12 to make decision whether a failure portion is in a stop electromagnetic valve 11, a relief pressure switching electromagnetic valve 10, the two-stage relief valve 7 or the cutoff valve 20. The results are signaled to a failure display device 13 to display the failure portion with symbols.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic circuit failure detection apparatus and detection method for identifying a failure part of a hydraulic circuit of an industrial vehicle, a hydraulic power shovel, or the like.

(Prior Art) Conventionally, as shown in FIG.
The discharged oil is guided to various actuators via the operation valve 15. The variable displacement pump 16 is a servo valve 18
The discharge amount is controlled by. The pump 19 is coaxial with the variable displacement pump 16 and is driven by a power source 17, and its discharged oil is guided to the pilot port of the servo valve 18 via the cant-off valve 2.O, and is also connected to the cut-off stop solenoid valve 11 and the relief valve. The pressure is guided through the pressure switching solenoid valve lO to the operation circuits of the cutoff valve 20 and the two-stage leaf valve 7, respectively. Excavation force amplifier function button 14, control device 50, cut-off stop solenoid valve 11, relief pressure switching solenoid valve 10
is connected to.

When the oil pressure exceeds the cutoff set pressure during operation, the cutoff valve 20 is activated and moves the servo valve 18 to perform a cutoff action that reduces the discharge amount of the variable displacement pump 16 and eliminates wasteful consumption of energy. 0 When a travel operation lever (not shown) is turned on, a signal is sent from the control device to the relief pressure switching solenoid valve IO, and the two-stage leaf valve 7 is switched to a high set pressure, increasing the travel force. When the excavation force increase function button 14 is turned on, a signal is sent from the control device 50 to the relief pressure switching solenoid valve 10 and the cut-off stop solenoid valve 11, and the two-stage leaf valve 7 becomes the high setting pressure and the cut-off valve 20 is turned on. The cut-off action of the variable displacement pump 16 is stopped, and the entire amount of high-pressure oil discharged from the variable displacement pump 16 is sent to the various actuators, so that a large excavation force can be obtained. This will be explained using the performance curve, ie, the P-Q diagram, of the variable displacement pump shown in FIG. The horizontal axis represents the pressure P, the lld axis represents the discharge amount Q, P□ is the high setting pressure of the relief valve, PL is the low setting pressure of the relief valve, P is the cutoff setting pressure, and Q is the cutoff setting pressure. This is the set flow rate, and during normal operation, the relief valve 7 has a low set pressure, so the P-Q line 1 diagram is represented by ABCD, but since the cut-off valve 20 is operating, AB
GHKD, when the travel control lever is turned ON, the relief valve 7 becomes the high setting pressure, and the cut-off valve 20 is activated, so it becomes ABGHLF, and when the excavation force increase function button 14 is turned ON, the relief valve 7 becomes the high setting pressure. Since the cut-off valve 20 stops operating, it becomes ABEF.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional hydraulic circuit, when it is felt that there is no power due to pressure drop during excavation work, it is necessary to identify the failure point that causes it. stops the operation of the machine and closes the relief valve 7 and relief pressure switching solenoid valve 1.
0. Attach a pressure gauge to each of the cut-off stop solenoid valves 11, start the machine, and according to the fault diagnosis diagram shown in Fig. 5, distinguish whether the excavation force is increased or normal operation is being performed in step 200, and determine whether the excavation force is increased. At step 201, operate the travel control lever to relieve the relief valve 7.
The pressure is read by the pressure gauge and it is determined whether the pressure is normal or not. If it is normal, the pressure is adjusted in step 202.

It is determined whether the pressure of the to-off stop solenoid valve 11 is normal or not, and if it is normal, it is determined that the cut-off valve is defective, and if not, it is determined that the pressure or to-off stop solenoid valve is defective.

If the pressure of the relief valve 7 is not normal, it is determined according to the step 203 whether the two-stage leaf valve is defective or the relief pressure switching solenoid valve is defective. In order to identify the location of the failure in this manner, the operation of the machine must be stopped, and a great deal of labor and time is required, leading to a decrease in work efficiency and an increase in repair costs. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a hydraulic circuit failure detection device and detection method that allows repairs to be made in a short period of time and at low cost by automatically identifying and displaying the failure location during work. It is said that

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a first invention of a hydraulic circuit failure detection device and detection method according to the present invention, which provides a two-stage setting pressure that can be switched to two high and low stages. relief valve and 2
A relief pressure switching solenoid valve that sends pressure oil to the operating circuit of the stage relief valve to switch the set pressure, a cut-off valve that reduces the discharge lid of the variable displacement pump during relief, and the cut-off valve operating circuit. In a hydraulic circuit equipped with a cut-off stop solenoid valve that sends pressure oil to stop the cut-off action, a pressure sensor 2 is installed in the discharge circuit of the variable displacement pump, and a pressure sensor 4 is installed in the operation circuit of the relief pressure switching solenoid valve. A pressure sensor 6 is installed in the operating circuit of the cut-off stop electromagnetic valve, and a flow rate detector (9) is installed in the return circuit of the two-stage relief valve, and upon receiving the signals, the fault location is identified and a display signal is sent to the fault display device. The second invention is characterized in that it is equipped with a control device that generates high pressure oil, and in the second invention, a pressure or flow rate setting value for determining the presence or absence of a failure in each part of the hydraulic circuit is determined and stored in the control device in advance, and the high setting pressure oil is If it flows into the circuit, it is determined whether there is a failure in the cut-off stop solenoid valve based on the pressure detected by the pressure sensor 6, then whether there is a failure in the relief pressure switching solenoid valve based on the pressure detected by the pressure sensor 4, and then After detecting the presence or absence of relief based on the flow rate detected by the flow rate detector, the presence or absence of a failure in the two-stage relief valve is determined based on the pressure detected by the pressure sensor 2, and then the presence or absence of a failure in the cut-off valve based on the detected flow rate by the flow rate detector. Determine,
When operating the travel control lever or when low set pressure oil flows into the circuit, the presence or absence of relief is detected based on the flow rate detected by the flow rate detector, and then the presence or absence of a failure in the two-stage relief valve is determined based on the pressure detected by pressure sensor 2. It is characterized by

(Function) According to the above configuration, the pressure and flow rate of each circuit in which the hydraulic system is operating is detected and compared with the set value of pressure or flow rate stored in advance in the control device to determine whether or not there is a failure in each part. , identifies the location of the fault that causes the pressure drop and automatically displays the fault location while the machine is operating.

(Example) Examples of the present invention will be described in detail below with reference to the drawings. 1st
The figure is an overall circuit diagram of the present invention, and shows a variable displacement pump 16.
is driven by the power [17], and the discharged oil is guided to various actuators via the operating valve 15. The discharge amount of the variable displacement pump 16 is controlled by a servo valve 18. The pump 19 is coaxial with the variable displacement pump 16 and is driven by a power source 17, and its discharged oil is led to the byronto port of the servo valve 18 via the cutoff valve 20, and is also connected to the cutoff stop solenoid valve 11 and the relief valve. The pressure switching solenoid valve 10 leads to the cutoff valve 20 and the two-stage relief valve 7 operating circuits. A pressure sensor 2 is installed in the discharge line 1 of the variable displacement pump 16, a pressure sensor 4 is installed in the operation circuit 3 of the two-stage relief valve 7, a pressure sensor 6 is installed in the operation circuit 5 of the to-off valve 20, and a pressure sensor 6 is installed in the operation circuit 5 of the two-stage relief valve 7. A flow detector 9 is provided in the return circuit 8 of the valve 7 . Control device 12 and pressure sensor 2.
4.6, flow rate detector 9, relief pressure switching solenoid valve 10,
The cut-off stop Igl magnetic valve 11, the failure display device 13, and the excavation force increase function button 14 are connected by wire.

When the oil pressure exceeds the cutoff setting pressure during operation, the cantoff valve 20 is activated, moves the servo valve 1B, and reduces the discharge amount of the variable displacement pump 16, thereby performing a cutoff action to eliminate wasteful consumption of the pump. . Turn the travel lever (not shown) to O.
When set to N, a signal is sent from the control device 12 to the relief pressure switching solenoid valve 10, the two-stage relief valve 7 is switched to a high set pressure, and the running force increases. When the excavation cuff function button 14 is turned on, a signal is sent from the control device 12 to the relief pressure switching solenoid valve lO and the force/throat-off stop solenoid valve 11, and the two-stage relief valve 7 becomes the high set pressure and the cut-off valve 20 is cut. Since the off-action is stopped and the entire amount of high-pressure oil discharged from the variable displacement pump 16 is sent to the various actuators, a large digging force can be obtained.

Next, the set values of the pressure of the pressure sensor and the flow rate of the flow rate detector for determining the function of each part will be explained. The set pressure of the pressure sensor 4 is the output pressure P4 of the relief pressure switching solenoid valve, and the set pressure of the pressure sensor 6 is the output pressure P6 of the cut-off stop solenoid valve. This will be explained below with reference to FIG.

Figure 3 is a P-Q diagram of a variable displacement pump, where PM is 2
The high set pressure of the stage relief valve, Pt is the low set pressure and the normal set pressure, aPc is the cut-off set pressure Q, and is the set flow rate of the return pipe 8 during cut-off action, which is 2 if the flow rate is 91 or higher. It is determined that the stage relief valve is in relief.

Q is the return pipe 8 when the cut-off action is stopped.
If the flow rate is 95 or higher at the set flow rate, it is determined that the cutoff action is stopped.

The failure detection method will be explained below using the circuit diagram shown in FIG. 1 and the flowchart shown in FIG. When the excavation force increase function button 14 is turned on in step 100 of the flowchart, the cut-off stop solenoid valve 11 and the relief pressure switching solenoid valve 10 are activated by a signal from the control device 12.
It switches from the position to the position ■, output pressures P6 and P4 are generated in each pressure sensor 6.4, and step 101.1
The pressure is verified in Step 02, and if the detected pressure is not ≧P6, the cut-off stop solenoid valve 11 failure C is detected, and if the detected pressure is not ≧P4, the relief pressure switching solenoid valve 10 failure B is detected, and the work equipment lever is turned ON and the step After confirming that the flow rate of the flow rate detector 9 is detected and relieved in step 104, step 105
If the detected pressure of the pressure sensor 2 is not ≧P, the 2-stage relief valve 7 is set to 11A, and the detected flow rate is set to ≧Q in step 106.
If not, check step 110 to determine if the cant-off valve is malfunctioning.
Turn off the digging force up function button and turn on the travel control lever.
After confirming relief by detecting flow rate≧Q1 in step 111, if the detected pressure of pressure sensor 2 is not≧PH, a failure A of the two-stage relief valve 7 is determined, and in step 120, the excavation force up function button 14 and the travel control lever are turned OFF. When the work equipment lever is turned ON at step 122, relief is confirmed by the flow rate detected by pressure sensor 121≧Q, and pressure sensor 2 is activated at step 122.
If the detected pressure is not PL, the control device 12 determines that there is a failure A of the two-stage relief valve 7, and displays the failure display device 1.
3 to display A, B, C, or D.

The above detection is normally performed all the time when the machine is in operation, but
When determining a failure, it may be activated and displayed and detected as necessary.

(Effects of the Invention) As described in detail above, the present invention provides a pressure sensor and a flow rate detector in each part of the hydraulic circuit, and compares the detected value with each value predetermined by the control device to detect failures. Since the location of the hydraulic circuit is identified and displayed on the fault display device, the fault location can be automatically known during work, providing a hydraulic circuit fault detection device and detection method that increases work efficiency and reduces repair costs. .

[Brief explanation of the drawing]

Fig. 1 is an overall circuit diagram showing an embodiment of the present invention, Part 2 is a flowchart showing the operation details of failure detection, Fig. 3 is a P-Q diagram of a variable displacement pump showing each set value, and Fig. 4 is a conventional overall circuit diagram, and FIG. 5 is a conventional failure detection diagram. 2.4.6...Pressure sensor 7...Two-stage relief valve 9...Flow rate detector lO...Relief pressure switching solenoid valve 11...
... Cut-off stop solenoid valve 12.50 ... Control device 13 ... Malfunction display device 14 ... Excavation force increase function button 15 ...
...Operation valve 16...Variable displacement pump 17...Power source 18...Servo valve 19...Pump 20...Cut-off valve

Claims (2)

[Claims] (1) A two-stage relief valve that can switch the set pressure between high and low levels, a relief pressure switching solenoid valve that sends pressure oil to the operating circuit of the two-stage relief valve to switch the set pressure, and a variable displacement pump during relief. In a hydraulic circuit equipped with a cut-off valve that acts to reduce the discharge amount of the variable displacement pump, and a cut-off stop solenoid valve that sends pressure oil to the operating circuit of the cut-off valve to stop the cut-off action, A pressure sensor 2 is provided in the circuit, a pressure sensor 4 is provided in the operating circuit of the relief pressure switching solenoid valve, a pressure sensor 6 is provided in the operating circuit of the cut-off stop solenoid valve, and a flow rate detector 9 is provided in the return circuit of the two-stage relief valve. A hydraulic circuit failure detection device characterized by comprising a control device that receives signals from these, identifies a failure part, and generates a display signal on a failure display device. (2) Set pressure or flow rate settings to determine the presence or absence of a failure in each part of the hydraulic circuit, store them in advance in the control device, and if high setting pressure oil flows into the circuit, it will be cut off based on the pressure detected by the pressure sensor 6. The presence or absence of a failure in the off-stop solenoid valve was determined, then the presence or absence of a failure in the relief pressure switching solenoid valve was determined based on the pressure detected by the pressure sensor 4, and the presence or absence of relief was then detected based on the flow rate detected by the flow rate detector 9. Afterwards, it is determined whether there is a failure in the two-stage relief valve based on the pressure detected by the pressure sensor 2, and then whether there is a failure in the cut-off valve based on the flow rate detected by the flow rate detector 9. When pressure oil flows into the circuit, the presence or absence of relief is detected by the flow rate detected by the flow rate detector 9, and then the pressure oil is detected by the pressure sensor 2.
A detection method characterized by determining the presence or absence of a failure in a two-stage relief valve based on the detected pressure.