JPH0747963B2 - How to diagnose hydraulic circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for quantitatively diagnosing an abnormality in a hydraulic circuit constituent device such as a pump or a valve.

[Conventional technology]

Conventionally, there has been a method of qualitatively diagnosing an abnormality occurrence by observing changes in hydraulic pressure waveforms on a suction side and a discharge side of a hydraulic circuit constituent device such as a pump.

Further, as a method for quantitatively diagnosing the degree of the failure, for example, in JP-A-49-30901, a discharge side pressure wave of a pump, a blower, etc. in operation is detected, and the detected pressure wave fluctuates. It is disclosed that the wave portion is extracted and is known from the state of change of the waveform. In this method, the degree of abnormality, for example, deterioration or failure of hydraulic circuit components is known from the spectral intensity ratio between the wave in a specific band and the other band when the device to be measured is operating normally.

[Problems to be Solved by the Invention]

However, this quantitative diagnosis method has a drawback that it requires the calculation of the spectrum intensity or the like for each failure mode, which makes the apparatus for diagnosis complicated.

INDUSTRIAL APPLICABILITY The present invention uniquely knows the degree of deterioration or failure of hydraulic circuit components without the need for a specially complex device for quantitative value conversion for knowing the degree of failure of a hydraulic circuit such as a pump or blower. It provides a diagnostic method that can

[Means for Solving the Problems]

The present invention, based on the absolute amount of the deviation of the ratio of the absolute amplitude value of the hydraulic pressure such as the discharge side pressure of the pump and its pulsation amplitude value, that is, the pulsation rate is compared with the reference pulsation rate in the steady state The degree of deterioration or failure of the hydraulic circuit components is diagnosed.

[Action]

The discharge pressure of the pump is f _e = N × Z / 60 where f _{e is} the pulsation frequency of discharge pressure (Hz) N: Pump speed (rpm) Z: Number of pump blades, vanes, cylinders, etc. It fluctuates or pulsates with the indicated frequency as the main component. The pulsation amplitude value P _AC shows a value different from that in the normal state if there is an abnormality in the pump or the like, for example, a vane defect or the like (see the example). However, since the magnitude of the pulsation amplitude value P _AC largely depends on the magnitude of the absolute amplitude value P _DC , it is necessary to make dimensionless as shown in the following equation in order to evaluate with a constant reference.

[Examples] Hereinafter, the present invention will be specifically described based on Examples.

FIG. 1 is a diagram showing a functional system for implementing the present invention.

In the figure, 1 is a hydraulic tank, and the discharge pressure of a pump 2 for discharging oil from the hydraulic tank 1 is a pressure sensor 3.
Measured at and displayed as an analog voltage signal. The analog voltage signal is separated by the DC component / pulsation component separation unit 4 into a voltage having an absolute amplitude value represented as a DC component and a voltage having a pulsation amplitude value represented as a pulsation component, and output to the signal processing device 5, respectively.

In this signal processing device 5, the pulsation rate is calculated by the following formula.

Reference numeral 6 denotes a determination device, in which the pulsation rate under normal conditions and the degree of abnormality due to the comparison deviation are input, and the pulsation rate calculated under the above operating conditions and the pulsation rate under normal conditions are compared. It is possible to make a comparison and determine a quantitative degree of abnormality based on the deviation.

Further, the diagnostic result, the pulsation rate calculation result, and the like are displayed on the display device 7 and stored in the storage device 8 and are corrected as a change in a normal value over time.

FIG. 2 shows an example of waveforms processed and output in each step of the functional system shown in FIG.

FIG. 3A shows an example of the waveform of the analog voltage signal output by the pressure sensor 3 shown in FIG.

The analog voltage signal (a) is output to LP in the signal processing device 5.
F (Low Pass Filtering) and HPF (High Pass Filtering) processed, absolute amplitude value (P _DC ) respectively
(B), and pulsation amplitude value ( _PAC ) (e) are converted and output.

Further, the pulsation rate is obtained from both of them, and the determination device 6
Enter in

This input pulsation rate is compared with the previously input normal pulsation rate and the comparison value is output as an absolute value.

By extracting the comparison absolute value, which is the final output, as the difference from the preset safe value, the degree of failure can be quantitatively calculated in real time.

FIG. 3 shows the normal pressure value (a) for the vane pump and the discharge pressure waveform when one vane is missing (b). From the figure, it can be seen that when an abnormality occurs in the pump, the regularity of the waveform changes and the pulsation amplitude increases 3 to 5 times. Therefore, the pulsation rate becomes 3 to 5 times the normal value, and it can be determined that the pump is abnormal.

〔The invention's effect〕

 The following effects can be achieved by the present invention.

(1) To detect the pulsation rate, only a DC / pulsation / separation unit consisting of a simple combination of filters or the like is sufficient, and a particularly complicated device is not required.

(2) A simple and quantitative abnormality diagnosis of the hydraulic circuit using the pulsation rate is possible.

(3) It is possible to manage the deterioration tendency of the pulsation rate and predict the failure of the hydraulic circuit.

[Brief description of drawings]

The accompanying drawings illustrate embodiments of the present invention. FIG. 1 is a functional system diagram for carrying out the present invention, and FIG.
FIG. 3 is an explanatory diagram of waveform processing output in each process as an embodiment of the present invention, and FIG. 3 is a normal pressure value (a) for a vane pump and a discharge pressure waveform diagram when one vane is missing (b). . 1: Oil tank, 2: Pump 3: Pressure sensor 4: DC / pulsation component separation unit 5: Signal processing device 6: Judgment device, 7: Storage device

Claims (1)

[Claims] 1. A pulsation rate represented by a ratio of an absolute amplitude value of hydraulic pressure and its pulsation amplitude value in a hydraulic circuit of an operating device is compared with a reference value of the pulsation rate calculated when the circuit is normal, A method of diagnosing a hydraulic circuit, which comprises diagnosing a degree of deterioration or failure of a hydraulic circuit constituent device based on an absolute amount of the deviation.