JPS61123786A - Trouble diagnosis device for hydraulic pump - Google Patents

Abstract

PURPOSE:To provide a trouble diagnosis device which may diagnoise a hydraulic pump with a high degree of accuracy even if the viscosity of hydraulic oil varies due to variations in the temperature of hydraulic oil, by issuing a trouble signal if such a condition that the variation rate of a variable displacement mechanism displaced in accordance with an instruction value exceeds an allowable value, continues for a long time exceeding a predetermined time set in accordance with the temperature of oil. CONSTITUTION:A RAM 26 determines such a condition that the displacement of a variable displacement mechanism 6a in a hydraulic pump 6 exceeds an allowable value. If the above-mentioned condition continues for a long time exceeding a predetermined time which is set in accordance with an oil temperature signal, the RAM delivers a swash plate control signal to a swash plate drive device 7 and a fail signal to an LED 20. With this arrangement the diagnosis of the hydraulic pump may be performed with a high degree of accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a failure diagnosis device for a hydraulic pump used as a power source for a hydraulic machine such as a hydraulic excavator or a crane, and a hydraulic system.

[Background of the invention]

Hydraulic machines such as hydraulic shovels and cranes, and hydraulic pumps in hydraulic systems are the most important machines that generate hydraulic energy. Therefore, failure of the hydraulic pump or deterioration in performance due to aging or the like will cause serious damage to the machines and equipment that use it. Therefore, it is required to detect performance deterioration or failure of hydraulic pumps. 6. Hydraulic circuit diagram of a failure diagnosis device for determining failure and performance deterioration (hereinafter referred to as failure) of conventional hydraulic pumps is shown in 9. As shown in the figure.

In the figure, 1 is the variable displacement hydraulic pump to be diagnosed, 1a is the swash plate and displacement variable mechanism (hereinafter simply referred to as the swash plate) of the variable displacement hydraulic pump 1, and 2 is the variable displacement hydraulic pump 1. A regulator that operates the swash plate 1a according to the discharge pressure, 3 is an oil pressure tester, which includes a pressure gauge 3a that measures the oil pressure, a flow meter 3b that measures the flow rate of oil, and a discharge pipe line of the variable displacement hydraulic pump 1 that throttles and discharges the oil. It consists of a manual variable throttle 3c that increases the pressure. 4a is a hydraulic pipe that connects the variable flow rate hydraulic pump 1 and the hydraulic tester, 4b is a hydraulic pipe that connects the hydraulic tester 3 and the hydraulic oil tank pipe, and 5 is a rotation for measuring the number of revolutions of the variable displacement hydraulic pump l. Show the total.

In a steady state, there are no hydraulic pipes 4a, 4b and no hydraulic tester 3, and the hydraulic pipes section a and section a are connected.To diagnose a failure of the variable displacement hydraulic pump 1.

First, the pipes connected to the discharge side of the variable displacement hydraulic pump 1 are separated from part a, and the pipes 4a and 4b and the hydraulic tester 3 are connected to the separated parts a and brvj. The hydraulic pump l is driven by a prime mover, and the rotational speed N of the variable displacement hydraulic pump 1 at that time is measured by a tachometer 5. In this state, variable aperture 3 c tttj
k, the pipe line is throttled until the pressure on the pressure gauge 38 reaches the set value P ref, and then the discharge amount Q of the variable displacement hydraulic pump l is measured using the flow meter 3b. In this case, the discharge amount is controlled by the swash plate 1 by the regulator 2 according to the discharge pressure.
Next, the theoretical discharge amount Qr=f of the variable displacement hydraulic pump 1 is calculated based on the rotation speed N and the set pressure P ref. Last K, discharge amount Q
ref and the discharge amount Q are compared, and when the difference exceeds an allowable value, it is determined that the variable displacement hydraulic pump 1 is out of order.

Such a failure determination device requires a part of the hydraulic piping to be disconnected and the piping 4a, 4b and the hydraulic tester 3 to be connected, which requires a lot of work time.

Further, when the hydraulic piping is disconnected, there is a risk that foreign matter such as dust may get mixed into the piping. Furthermore, during diagnosis, it is necessary to operate the variable throttle 3C and read the indicated values of the pressure gauge 38 and flow meter 3b, which also requires a lot of time and makes the diagnosis troublesome.

[Objective of the Invention 1 An object of the present invention is to provide a failure diagnosis device for a hydraulic pump that can accurately and quickly diagnose the presence or absence of a failure even when the viscosity of pressure oil changes.6 [Summary of the Invention] ] In order to achieve the above object, the present invention provides a command value for displacing the variable displacement mechanism of a hydraulic pump by a predetermined amount, and a variable displacement displacement volume based on this command value! ! The absolute value of the difference with the system is compared with a predetermined tolerance value, and a failure signal is output when the absolute value exceeds the tolerance value for a predetermined period of time set by the oil temperature. It is characterized by what it did.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a control circuit diagram of a failure diagnosis device for a hydraulic pump according to an embodiment of the present invention.

In the figure, 6 is a variable displacement hydraulic pump of 1iTOX type, 6a is a swash plate or oblique shaft variable displacement displacement machine #l of the hydraulic pump 6 (hereinafter, this is represented by the swash plate), and 7 is an input. a swash plate drive device 8 that drives the swash plate 6a according to a signal;
is a displacement meter that detects the amount of displacement of the swash plate 6a, and the detected slant 4
Outputs a displacement signal Y according to the amount of displacement of Ji6a. 9
is an operating lever for operating the hydraulic pump 6, which outputs an operating signal X according to the amount of operation. 10 is an oil mixer that outputs a signal TO according to the oil temperature, and 11 is a swash plate drive device! 7 is a hydraulic power source connected to it, 12 is a tank connected to the diagonal FLg and the moving device.

20 is a light emitting diode, and 21 is a control device configured using a microcomputer, which inputs an operation signal X, a displacement signal Y, and an oil temperature To, and outputs a swash plate control signal to the swash plate drive unit W17. , and also outputs a failure signal to the light emitting diode 20.

22 is a multiplexer that switches and inputs the operation signal X, displacement signal Y, and oil temperature signal To, and 23 is an A/D that converts the operation signal X, displacement signal Y, and oil temperature signal To into digital values.
Converter, 24, operation signal X, displacement signal Y, oil temperature signal To
CPU, 25, which performs predetermined calculations and control based on
is a ROM that stores the calculation and control procedures of the CPU 24.
, 26 is a RAM that temporarily stores input takes, calculated values, etc., and 27 is an output section that outputs signals obtained by calculation and control to the swash plate driving device 117 and the light emitting diode 20.

FIG. 2 is a hydraulic circuit diagram of the swash plate drive device [7, where 71 is a cylinder, 72 is a piston that reciprocates within the cylinder 71, and 73 is a hydraulic circuit diagram of the swash plate drive device [7].
a, 73b, 73c, and 73d are solenoid valves, and this m solenoid valve 7
By receiving the ON signal to 3a and 73b, the oil pressure g1
1 pressure oil is led to the A chamber of the cylinder 71, the oil in the B chamber is released to the tank 12, and the piston 72 is moved by the displacement signal Y of the swash plate 6a.
The solenoid valves 73e and 73d, which move in the direction of increasing
When the signal is received, pressure oil is guided to chamber B of cylinder 71.

The piston 72 and the swash plate 6 move in the direction in which the displacement signal Y decreases.
When the electromagnetic valves 73a and 73d, which move the cylinder 71, receive an ON signal, the oil flow into and out of the A and B chambers of the cylinder 71 is stopped, and the swash plate 6a is stopped.

Next, the operation of the failure diagnosis device will be explained with reference to the flowcharts shown in FIGS. 3 to 8.

The operation signal X, displacement signal Y, and oil fox signal To are stored in the RAM 26 via the multiplexer 22 and A/D conversion a123 (block a in FIG. 3).

Next, control is performed to drive the swash plate 6a (block b in FIG. 3). The detailed procedure for this control is shown in FIG. 4-1. In block b, first, the operation signal Calculating the difference ΔX (ΔX=X-Y) (block b1); determining whether the deviation ΔX is positive, negative, or 0 (block b2);
If the deviation ΔX is negative, a signal is sent to the swash plate drive device 7 to reduce the displacement of the swash plate 6a, that is, the solenoid valves 73c, 7
Block b3 outputs the ON signal of 3d from the output section 22.
), a signal that stops the swash plate 6a if the deviation ΔX is 0,
In other words, the ON signal for the solenoid valves 73a and 73d is output (block b4), and if the deviation ΔX is positive, the signal that increases the displacement of the swash plate 6a, that is, the solenoid valves 73a*, 73
The ON signal b is outputted (block b5). In this way, normal swash plate control is performed by blocks a and b in FIG.

Next, FIG. 5 shows details of the procedure of block C, in which failure determination of the hydraulic pump 6 is performed as in block C.

In block C - first subtract the allowable value Δ from the operation signal X to find the lower limit judgment value Xx (X1 = X - Δ), and then
Store in AM26 (block CI) 6th block C
As shown in 2, the upper limit judgment value Xg (Xz=X+Δ) is obtained by adding the operation signal X and the allowable value Δ, and this is
6 to store 8 then as shown in block C3.

Displacement signal Y and lower limit judgment value Xl stored in RAM 26
is extracted, and it is determined whether the displacement signal Y is greater than or equal to the determination value X1. If the displacement signal Y is greater than or equal to the determination value X1, the process moves to block c4.

This time, the displacement signal Y and the upper limit judgment value X2 are RA'd and taken out from 126, and the displacement signal Y is judged f1! It is determined whether it is less than or equal to Xs. If the displacement signal Y is less than or equal to the determination value X2, the process moves to block c5. In block c5, error flag data, which is to be stored in advance in a predetermined address in the RAM 26, is set to "0". in this case,
The error flag data "0" indicates block e3. Since it is determined that the displacement signal Y is within the predetermined range at c4, this means that there is no failure in the hydraulic pump 6.

On the other hand, if it is determined in block c3 that the displacement signal Y is less than the determination value X1, or if it is determined in block C4 that the displacement signal Y exceeds the determination value Xz, the process moves to block c6. In block c6, the error flag data is set to "1", which indicates that the displacement signal Y is outside the predetermined range and that the hydraulic pump 6 is out of order.

Here, we will explain the allowable value Δ 6 Normally, in structures such as the swash plate of a hydraulic pump, the operation signal They do not match completely and there are differences. However, as long as such mechanical play is within a certain range, there is no problem with the operation of the hydraulic pump.

There is no need to regard this as a failure; therefore, the operation signal X and displacement signal Y caused by mechanical play within a certain range.
In order to exclude this difference from failure, this difference is treated as an allowable value Δ. The value of the allowable value Δ can be determined for each hydraulic pump.

Next, the error counter setting value Cε shown in block d shown in FIG. 3 is corrected. The details will be explained with reference to FIG.

The error counter setting value Ca is used to calculate the delay time in the failure display postponement process for the primary block e. In the process, in block d1 of FIG. 6, a correction coefficient Kc is read from the error count correction coefficient table of FIG. 7 based on the oil temperature signal To. Next, in block d2, the count setting value Cε0 at the oil temperature T o o is multiplied by the correction coefficient Kc at the actual oil temperature to obtain the error counter setting value Cε.

Here, the meaning of correcting the error counter set value Cε using the oil temperature will be explained. In the swash plate drive device 7 shown in FIG.
The amount of pressure oil flowing into the cylinder 71 per unit time Q
is inversely proportional to the viscosity of the oil.

Also, the viscosity of oil increases exponentially as the oil temperature decreases. In other words, as the oil temperature decreases, the amount of oil flowing into the cylinder per unit time Q decreases, so the piston 72
The speed of the swash plate 6a decreases, and it takes a long time for the swash plate 6a to follow and catch up with the operation signal X. Therefore, the optimum value of the error delay time, which will be described later, needs to be increased as the oil temperature decreases. Since the curve of the correction coefficient Kc with respect to the oil temperature To shown in FIG. 8 differs depending on the hydraulic equipment, the model of the hydraulic system, and the hydraulic oil, the optimum value is set for each.

Next, the 81st! Make it I.

In block e1 of FIG. 8, error flag data is retrieved from the RAM 26, and it is determined whether the value is "0" or not. If the error flag data is “0”, the RA
The value of the error counter set at a predetermined address of M26 is set to 0 as in block e2. Here, the error counter counts the set delay time, and is incremented once each time the processing of blocks a to e is repeated. The process of block e2 is a process when there is no failure, and no delay is necessary, so the error counter is set to 0.

If it is determined in block e1 that the error flag data is not rOJ, then the value of the error counter in the RAM 26 is taken out, and it is determined in block e3 whether this value is a preset value Cε. If the set value Cε has not been reached, that is, if the predetermined delay time has not been reached, 1 is added to the value of the error counter in the RAM 26 as in block e4, and the processing from block a in FIG. 3 is performed again. On the other hand, in block e3, if the value of the error counter is the set value Ca, that is, if it is determined that the predetermined delay time has been reached, a signal is output from the output section 27 as in block e5.

The light emitting diode 20 is caused to emit light.

In the above process, the operating lever 9 is rapidly operated,
If the #4 plate 6a cannot follow up, the process of block C6 in FIG. 5 is performed, the error flag data becomes rlJ, and the processes of blocks el, e3 and e4 are performed.

However, the error counter set value Ce is set so that the swash plate 6 has more time to catch up with the sudden operation of the device lever 9, so the swash plate 6a follows the operating lever 9 within the set value. Therefore, at the time of following block c5. e1. The processing of e2 is performed and no failure signal is output for one light emitting diode 20. On the other hand, in the case of a continuous failure, block c6+ el+
e3. Since the process passing through e4 is repeated, the value of the error counter increases by 1 each time it is repeated, and finally reaches the set value Cε, processing by block e5 is performed, and a failure signal is output.

In addition, in place of the light emitting diode 20, other indicators, alarm amounts, or a combination of these may be used.
Furthermore, the output of the output section 27 can be used in conjunction with an indicator or an alarm,
It can be used alone to drive the emergency stop mechanism of a hydraulic pump, or can be used to monitor failures. and,
When the output of the output unit 27 is used to drive the emergency stop mechanism of the hydraulic pump, setting the delay time corrected based on the oil temperature is particularly effective because unnecessary stoppage of the hydraulic pump can be avoided.

According to the second embodiment, there is no need to disconnect the hydraulic piping for fault diagnosis of the hydraulic pump.

It is possible to prevent foreign matter from entering the hydraulic circuit and automatically and quickly diagnose failures. Furthermore, since a microcomputer is used, similar processing can be sequentially performed on each of a large number of hydraulic pumps, and failure diagnosis of each hydraulic pump can be performed simultaneously.

In the embodiment described above, a signal obtained from the operating lever 9 is used as the operation signal, but the signal is not limited to this, and a command signal for the final swash plate position to the swash plate drive device 7 may be used.

〔Effect of the invention〕

As explained above, the present invention compares the absolute value of the difference between the operation signal and the displacement signal with a predetermined tolerance value, and maintains a state in which the absolute value of this difference exceeds the tolerance value for a predetermined time period set depending on the oil temperature. When the above conditions continue, a signal indicating a failure is output, making it possible to obtain a failure diagnosis device that can accurately diagnose even if the viscosity of the hydraulic fluid changes. Since there is no need to make connections between pipes, this diagnosis can be performed quickly.

[Brief explanation of drawings]

FIG. 1 is a control circuit diagram of a failure diagnosis device according to an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram of a swash plate drive device, and FIG. 3 is a flowchart of the main parts shown in FIG. 1. 4, 5, and 6 are detailed flowcharts of each block in FIG. 3, and 713! I is an explanatory diagram showing a correction coefficient curve for oil temperature, FIG. 8 is a partial detailed flowchart of FIG. 3, and FIG. 9 is a hydraulic circuit diagram of a conventional failure diagnosis device. 6...Variable displacement hydraulic pump, 6a...
Swash plate, 7... Swash plate drive device, 8... Displacement meter, 1o... Oil temperature gauge, 21 Control device, X...
...Operation signal, Y-old...Displacement signal, To-...
...Oil temperature signal. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Oil temperature T. Figure 8 Figure 9

Claims (1)

[Claims] 1. In a hydraulic pump equipped with a variable displacement mechanism, means for generating an operation signal to displace the variable displacement mechanism by a predetermined amount, means for detecting a displacement signal of the variable displacement mechanism, and operation of the operation signal generation means. means for comparing the absolute value of the difference between the signal and the displacement signal of the displacement signal detection means with a predetermined tolerance value, and a state in which the absolute value in the comparison means exceeds the tolerance value is set depending on the oil temperature. 1. A failure diagnosis device for a hydraulic pump, comprising a delay means for outputting a failure signal when the failure continues for a predetermined period of time or more.