JPH0418615B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a leakage measuring device for a hydraulic system. Internal leaks from hydraulic equipment such as power shovels and construction machinery vary depending on the oil used, pressure, and temperature.
Furthermore, changes over time (wear and deterioration, etc.) in the equipment and oil used can promote leaks. The same can be said of internal leaks in the piping system of newly manufactured hydraulic equipment. Such leakage causes problems in operation. For example, if an internal leak occurs in the hydraulic system of a power shovel, the specified output will not be enough, which will of course significantly reduce work efficiency, and the bucket and arms will move unnaturally, which can be dangerous. It turns out. For this reason, it was necessary to strictly conduct leak tests during inspections and periodic inspections and maintenance before product shipment. This type of inspection method reproduces actual operating conditions and inspects buckets, booms,
Measure the movement of arms, or
This was to measure the degree to which the boom and arms naturally lowered due to their own weight. Therefore, in leak testing each of the front parts of a power shovel, that is, the movable parts consisting of the bucket, boom, and arm, it is necessary to measure the load, travel distance, time, oil pressure, and oil temperature at the same time. It required highly skilled workers. The present invention has been made in view of the above-mentioned problems, and provides a leakage measuring device for a hydraulic system that is easy to operate, eliminates the need for skilled personnel, and can accurately measure leakage indoors. . That is, the present invention provides a display device that displays a work procedure based on an output from a central control device, a hydraulic device that supplies a predetermined hydraulic pressure to a test machine based on a command from the central control device, and a reference value storage circuit that stores a reference value of a leak amount; a measurement circuit that measures a displacement generated in a measuring cylinder incorporated in the hydraulic device; and a case where a predetermined hydraulic pressure is supplied to the test machine by the hydraulic device. calculating the leakage amount of the test machine and the hydraulic system from the output of the measurement circuit, and the leakage amount of the hydraulic system when the hydraulic system is operated without supplying hydraulic pressure to the test machine; The leak amount of the test machine is calculated from the difference between the leak amount of the test machine and the hydraulic system and the leak volume of the hydraulic system, and the calculated leak volume of the test machine is stored in advance in the reference value storage circuit. an arithmetic circuit that performs a comparison judgment with a stored reference value based on a command from the central control device; a pendant that supplies a work procedure signal to the central control device according to the machine under test; and a vehicle model number receiving device that accepts the model number of the test machine for supplying a test oil pressure value signal, an operation procedure display signal, and a reference value comparison signal according to the test machine from a reference value storage circuit. This is a leak amount measuring device for a hydraulic system characterized by the following. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of the present invention. 1 in the figure is a central control unit CPU. The central control device 1 is supplied with signals from a vehicle model number receiving device 3 for receiving the model number of the test machine 2 and a pendant 4 having a push button switch for proceeding with the work. Central control device 1
is configured to output a predetermined signal to the display device 5 and the hydraulic device 6. The display device 5 has a function of displaying work order, work instructions, and results. The hydraulic system 6 is configured to supply test hydraulic pressure to the test machine 2 via a measuring cylinder 7 that measures the amount of leakage. The oil temperatures of the test machine 2 and the hydraulic system 6 are monitored by an oil temperature sensor 8. The outputs of the oil temperature sensor 8 and the measuring cylinder 7 are supplied to a measuring circuit 9 for processing. An arithmetic circuit 10 is connected to the measurement circuit 9, which uses the signal processed by the measurement circuit 9 as a measured value. Connected to the arithmetic circuit 10 is a reference value storage circuit 11 that stores pressure setting reference values sorted by vehicle model number, reference values for pass/fail determination of measurement results, work order, display, etc. Predetermined signals are supplied to each other between the measuring circuit 9, the arithmetic circuit 10, the reference value storage circuit 11, and the central control unit 1. Further, the hydraulic device 6 and the metering cylinder 7 constitute a metering hydraulic device 20 shown in FIG. FIG. 21 shows an oil tank for metering. An oil level gauge 22 with a thermometer, a level switch 23, and a thermoswitch 24 are attached to the oil tank 21. The level switch 23 is an oil amount monitoring switch, and, like the thermo switch 24, stops the electric motor 25, which will be described later, in order to protect the hydraulic system 6 when the oil level drops below a specified level. The thermoswitch 24 is a temperature monitoring switch for the hydraulic oil, and normally has an upper limit of 60° C., and stops the electric motor 25 when the temperature exceeds that temperature. Further, a magnet 26 is provided inside the oil tank 21. The magnet 26 is designed to adsorb iron powder in the oil and prevent wear and tear on each hydraulic device. oil tank 21
The oil in the tank is passed through the tank filter 27 to the pump 2.
8. pump 28
has the function of generating a predetermined hydraulic pressure and supplying oil. An electric motor 25 is connected to the pump 28 to drive it. The pump 28 and the electric motor 25 are connected by a shaft joint 29. A check valve 30 is attached to the outlet of the pump 28 to prevent backflow of discharged oil. pump 2
8 is connected in front of the check valve 30 via an oil pipe 31 to electromagnetic valves 32a, 32b, and 32c. Check valve 30 and solenoid valve 32 of oil pipe 31
A flow regulator 33 is installed between a. The flow regulator 33 is for adjusting the flow rate of the metering oil circuit. A measuring cylinder 35 is attached to the solenoid valve 32a via an oil pipe 34. An electromagnetic scale 36 is connected to the measuring cylinder 35 . A check valve 37 is attached to the oil pipe 34. Metering cylinder 35 is adapted to set the maximum test flow rate. The electromagnetic scale 36 has a function of measuring the amount of oil, and is configured to supply a pulse signal corresponding to the measured amount to the measuring circuit 9. The oil pipe 31 between the check valve 30 and the flow regulator 33 has three oil pipes 31a, 31b, and 31c branching off. One of the oil pipes 31a is connected to the solenoid valve 3.
2b and 32c. Unique oil pipe 3
A pressure gauge 38 is attached to 1b. A relief valve 39 and an electromagnetic relief valve 40 are attached to the remaining oil pipe 31c, and the tip of the oil pipe 31c is connected to another oil pipe 41. Relief valve 39 and electromagnetic relief valve 40
receives the signal set by the central controller 1,
It is designed to set the specified oil pressure. One end of the oil pipe 41 is connected to an oil pipe 42 installed between the three electromagnetic valves 32a to 32c, and the other end communicates with the inside of the oil tank 21. The oil pipe 41 has
A return filter 43 is attached to filter the return shaft. Further, the electromagnetic valve 32a is a switching valve that switches the operation of the metering cylinder 35, and is adapted to operate according to commands from the central control device 1. That is, when the solenoid valve 32a is energized on the backward side by a signal from the central controller 1, the solenoid valve 32a opens the metering cylinder 3.
By supplying oil into the measuring cylinder 5, the measuring cylinder 35 is set in a ready state for measurement. On the other hand, when the forward side of the solenoid valve 32a is excited by a signal from the central control device 1, a specified pressure is applied to the oil in the metering cylinder 35. That is, pilot check valves 44 provided corresponding to measurement points A, B, and C of the test machine 2 from the measuring cylinder 35
The solenoid valve 32a is energized on the forward side only after the pressures at the points up to the inlets of the valves a, 44b, and 44c become the same pressure. Hydraulic pressure is supplied to A, B, and C individually to the test machine, and oil supply to a desired location, for example C, is started by operating the solenoid valve 32c. 45a, 45b, 45c are test machine 2
46 is a pressure gauge for measuring the pressure inside the pipe. Next, the metering hydraulic device 2 configured as described above will be explained.
The action of 0 will be explained based on an actual example of a hydraulic circuit leak test of a power shovel, boom, arm, and bucket. First, the model of the power shovel is input into the vehicle model number receiving device 3. Next, the input data is used to extract the specified oil pressure for testing from the reference value storage circuit 11 via the central controller 1. Next, this signal is sent to the hydraulic device 6 as a set pressure signal, and the signal is sent from the hydraulic device 6 to the electromagnetic relief valve 40 shown in FIG. The hydraulic system 6 operates the pump 28 before receiving the set pressure signal, and at the same time as the signal is received, the electromagnetic relief valve 40 operates to maintain a specified pressure and wait for a command to supply oil to the test machine 2. On the other hand, the central control device 1 calls up the work order and work instructions from the reference value storage circuit 11, and displays the display device 5,
That is, a predetermined display is made using a cathode ray tube or the like.
The subsequent work progresses sequentially by pressing the switch on the pendant 4 in accordance with the instructions displayed on the cathode ray tube. Here, the oil supply hose to the test machine 2 is connected with a coupler (hose coupling fitting), and at the same time, the test machine oil temperature sensor 8 is attached to complete the preparation. Next, prior to testing the test machine 2, the measuring cylinder 7
Perform an internal leak test on the hydraulic system 6. The forward side of the solenoid valve 32a is excited (reference: forward side = measurement, backward side = replenishment of metering oil to the metering cylinder) The electromagnetic relief valve 40 supplies the set specified oil pressure to the forward side of the metering cylinder 35. At this time, all circuits to the test machine 2 are closed. As a result, leaks in the check valve 37 including the metering cylinder 7, the pilot check valves 44a...44c, and their piping are detected by the electromagnetic scale 36, and _L2 (cc/min) is calculated by the measurement and calculation circuits 9 and 10. When the metering cylinder, hydraulic system 6, and internal leak tests are completed, the work instruction on the cathode ray tube indicates the start of testing of the test machine 2, and the pendant 4 is pressed accordingly. The A circuit of the solenoid valve 32b is energized, the pilot check valve 44a is opened, and the specified hydraulic pressure is supplied to the A circuit (power shovel boom circuit system leak test). The measurement will now start. The measurement start time is 6 seconds after the solenoid valve 32b is activated, taking into account the expansion of the piping system including the test machine (6 seconds is set empirically based on various experiments). value). When one minute has elapsed from the start of the measurement (the measurement time can be changed arbitrarily), the circuit automatically switches to the next B circuit and proceeds in the same measurement order as the A circuit. Naturally, the oil temperature during the test is constantly monitored by the oil temperature sensor 8, and changes in oil viscosity due to temperature changes are corrected using correction coefficients S ₂ (measurement system oil temperature correction coefficient) and S ₁ (test machine oil temperature correction coefficient). The true value (value for a constant oil temperature) is determined by multiplying the leakage amount by the coefficient. However, for power shovels where there is no noticeable change in oil temperature, if the oil temperature at the time of the test is specified (approximately 50℃ for power shovels) and the measurement is taken when that temperature is reached, there is no need to perform oil temperature correction. good. Similar to the internal leak test, the leak amount measurement is performed by detecting the movement of the rod of the measuring cylinder 35 with the electromagnetic scale 36, and by using the measurement and calculation circuit 10 to detect the movement of the rod of the measuring cylinder _35.
Calculate (cc/min). The leakage amount of the test machine 2 to be determined is: Leakage amount of the test machine 2 (cc/min) = (L ₁ × S ₁ ) − (L ₂ × S ₂ ) ...(1) or = L ₁ −L ₂ ...(2) [However, since the power shovel is measured within the specified temperature range, it is performed using formula (2) without multiplying by the oil temperature correction coefficient. ] The value calculated by equation (1) or (2) is displayed on the display device 5.
(on a cathode ray tube and printer), and at the same time, it is compared with the specified leakage amount in the reference value storage circuit 11 and a pass/fail judgment is also displayed. The table below shows the open/close states of the solenoid valves.

【table】

[Table] As described above, this leakage measuring device for a hydraulic system has the following effects. Tests similar to those in operating conditions can be performed without moving or running the test equipment in a fixed location indoors. For example, when testing a power shovel, it can be stored in an installation area of 10 m x 11 m (110 m ² ), and is free from adverse conditions such as outdoor wind and rain and sludge adhesion from driving. In the past, testing required at least two operators. However, according to this device, only one operator can judge the measurement results and pass/fail. The measurement data is free from errors due to individual differences. The operator can operate the device according to the instructions displayed on the CRT (cathode ray tube), etc., according to the instructions from the CPU, and the device automatically measures the data, eliminating the need for troublesome tasks such as using the pointer of the measuring device, reading numbers, and writing things down. freed from work. Further, since the operation is easy, the operation does not need to be performed by a skilled person. As described above, according to the leakage measuring device for a hydraulic system according to the present invention, the leakage amount can be measured indoors and accurately with simple operation and without the need for a skilled person.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a schematic configuration of a metering hydraulic system. DESCRIPTION OF SYMBOLS 1... Central control device, 2... Test machine, 3... Vehicle model number acceptance device, 4... Pendant, 5... Display device, 6... Hydraulic system, 7... Measuring cylinder, 8
... Oil temperature sensor, 9 ... Measurement circuit, 10 ... Arithmetic circuit, 11 ... Reference value storage circuit, 20 ... Leak amount measuring device for hydraulic system.

Claims (1)

[Claims] 1. A display device that displays work procedures based on the output from the central control device, a hydraulic device that supplies a predetermined hydraulic pressure to the test machine based on commands from the central control device, and a reference value for the leakage amount of the test machine. a reference value storage circuit for storing a reference value storage circuit for storing a reference value, a measurement circuit for measuring a displacement generated in a measuring cylinder incorporated in the hydraulic device, and a measurement circuit for measuring a displacement generated in a measuring cylinder incorporated in the hydraulic device; and calculates the leakage amount of the hydraulic system from the output of the measurement circuit and the leakage amount of the hydraulic system when the hydraulic system is operated without supplying hydraulic pressure to the test machine, and The leak amount of the test machine is calculated from the difference between the leak amount of the hydraulic device and the leak amount of the hydraulic device, and the calculated leak amount of the test machine and a reference value stored in advance in the reference value storage circuit are calculated. an arithmetic circuit that performs a comparison judgment based on a command from the central control unit; a pendant that supplies a work procedure signal corresponding to the test machine to the central control unit; The vehicle type number receiving device receives the model number of the test machine for supplying a test oil pressure value signal, an operation procedure display signal, and a reference value comparison signal according to the test machine. Leak amount measuring device for hydraulic equipment.