JP2717806B2 - How to display pulsating pressure of reciprocating pumps - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure display method, and more particularly to a pressure display method in a pulsating circuit such as a reciprocating pump.

[Prior Art] When displaying hydraulic pressure, pneumatic pressure, and other fluid pressure, a method of directly connecting a pressure gauge to a fluid circuit and displaying the pressure, and a method of connecting a pressure detector to the fluid circuit and extracting the electrical signal as an electric signal. Signals are converted, converted and displayed as pressure.

In a pulsating fluid circuit such as a reciprocating pump, the pressure gauge is damaged at an early stage due to fatigue destruction due to the pulsation. Therefore, a throttle valve is provided so that the pulsation hardly acts directly on the pressure gauge. On the other hand, in the method of electrically detecting pressure, damage due to pulsation can be avoided because there is no movable part due to pulsation, but if the frequently changing pressure is displayed as it is, the pressure displayed on the display becomes difficult to read. Therefore, a method of averaging and displaying the pressure within a predetermined time has been adopted.

One of the related fields of the present invention is a reciprocating ultra-high pressure pump using a hydraulic booster system. FIG. 1 shows an example of a circuit diagram of the pump device. In the figure, a hydraulic pump 100 is connected to a pressure intensifier 102 via a hydraulic line 101. Ten
3 is a secondary liquid suction line via a check valve 105 and a discharge line
The secondary liquid is discharged through 106. In such a device, when displaying directly with a pressure gauge, the discharge line
This is performed by connecting a pressure gauge to 106, and when electrical detection is performed, it is common to mount a pressure detector on the hydraulic pipeline 101 and perform the detection.

However, since the pressure of the secondary liquid applied in the apparatus is an ultra-high pressure of 100 to 400 MPa, the price of the pressure gauge is expensive, and it is not suitable for remote display as a general problem when the pressure gauge is used. That is. Therefore, in this field, a method of displaying the pressure by electrically detecting and converting the primary oil pressure is often used.

[Problems to be Solved by the Invention] In the electric pressure detection and display method, when displaying a pressure in a time zone where a pressure change is relatively large such as when reciprocating motion of a reciprocating pump is switched, the pressure that greatly changes in a short time is displayed. Displaying sequentially will make the display unstable and difficult to see,
There is a problem that it is difficult to determine the actual operating pressure. Therefore, conventionally, in a region where the pressure largely drops, a process of excluding a sudden drop pressure from the display target is performed to reduce the fluctuation of the display pressure. However, the actual change in the liquid pressure discharged from the pump is detected as a change in the waveform shown in FIG. 4 as an example. When the pressure is displayed based on the above method, it is processed as a pressure drop area at point A. ,
The pressure PU will be displayed for a certain period of time. That is, a pressure higher than the actual pressure is displayed. The reason for this is that the pressure is detected by the primary oil pressure, and the circuit oil pressure suddenly rises immediately before the pump operation direction is switched at the stroke end of the reciprocating pump, and then suddenly drops and then returns to the steady pressure. Occurs to return to. Such a phenomenon becomes more conspicuous as the reciprocating operation of the pump becomes faster.

[Means for Solving the Problems] The present invention aims to minimize such a display pressure error, and specifically employs the following method. That is, in a reciprocating pump configured to discharge a secondary liquid by reciprocatingly driving a pressure intensifier by hydraulic pressure,
It has a pressure detector provided in the hydraulic line, a stroke end detector of the piston of the pressure intensifier, an arithmetic device for performing arithmetic processing of the detection value of each detector, and a display device for displaying the arithmetic result in the arithmetic device. When a detection signal is output from the stroke end detector of the pressure intensifier, the value before the signal output is displayed on the display for a predetermined time from the output of the signal, and otherwise, the detection value of the pressure detector is detected by the arithmetic unit. An average detection value within a predetermined time is calculated, and a value based on the average detection value is displayed on a display to achieve the object.

Example An example will be described.

In the configuration shown in FIG. 1, the pressure oil generated by the hydraulic pump 100 is sent to the pressure intensifier 102 through the hydraulic line 101 via the direction control valve 107. The direction control valve 107 has an operation of switching the operation direction of the pressure intensifier 102 by switching the direction of supply of the pressure oil to the pressure intensifier 102. The booster 102 has a built-in piston 108 in the right-hand and left-hand directions according to the direction in which the pressure oil is supplied, and alternately performs suction and discharge operations. Directional control valve 107 is pressure booster 1
The switching is controlled by the detection signals of the stroke end detectors 109 and 110 arranged in 02. Hydraulic line 101 has pressure detector 111
Is provided, and the pressure in the hydraulic pipeline 101 can be detected. The nozzle 112 is connected to the end of the discharge pipe 106, and an accumulator 113 may be provided in the discharge pipe 106 between the pressure intensifier 102 and the nozzle 112 as needed.

Now, when the hydraulic pump 100 is driven and the pressure oil is
From the intensifier 102. If the direction switching valve 107 is in the illustrated state, the right side of the pressure intensifier 102 is the discharge stroke, and the left side is the suction stroke. Eventually, when the piston 108 of the pressure intensifier 102 approaches the right stroke end, the detector 110 detects the piston 108 and issues a signal. Then, the signal from the detector 110 is
The control device 114 operates to switch the direction control valve 107 based on the signal. When the direction control valve 107 is switched, the pressurized oil is sent to the pressure intensifier 102 along the path indicated by the dashed line, and the pressure intensifier 102 has a suction stroke on the right side, a discharge stroke on the left side, and a piston 108 on the left side in the drawing. Move in the direction. When the piston 108 approaches the left stroke end, the detector 109 detects the piston 108 and emits a signal.
14, the direction control valve 107 is switched by a signal from the control device 114, and pressure oil is sent to the pressure intensifier 102 through the path of the hydraulic line 101 indicated by a solid line in the figure to operate the pressure intensifier 102. Hereinafter, the pressure intensifier 102 is reciprocated continuously in the same manner.

Here, it is ideal that the pressure oil in the hydraulic line 101 discharged from the hydraulic pump 100 always has a constant pressure in any state. However, due to economical efficiency, device dimensions, and other restrictions, the hydraulic pump 100 In general, the pressure fluctuates under the load condition of the pressure intensifier 102 due to the capacity of the hydraulic line 101, the pipe resistance of the hydraulic line 101, the viscosity of the hydraulic oil, and the like. In particular, the pressure fluctuation when the moving direction of the piston 108 of the pressure intensifier 102 is switched becomes the largest. Therefore, processing is performed so that the signal generated from the detectors 109 and 110 when the piston 108 of the pressure intensifier 102 reaches the stroke end is reflected on the display pressure.

Specifically, the pressure in the hydraulic line 101 and the detectors 109, 1
The timing with the signal emitted by the signal 10 has a relationship as shown in FIG. That is, during the period from when the detectors 109 and 110 detect the stroke end of the piston 108 until the movement direction of the piston 108 is actually switched, the pressure of the hydraulic pipeline 101 temporarily increases,
After suddenly falling along with the moving direction of the piston 108, the desired steady pressure is reached. This is due to an operation delay of the mechanical system from when the signals from the detectors 109 and 110 are received to when the direction control valve 107 is operated and the piston 108 switches the moving direction. Therefore, when converting the pressure of the hydraulic line 101 and displaying it as the pressure of the discharge line 106, the value detected by the pressure detector 111 is usually extracted at predetermined intervals within a predetermined sampling time, and the extracted values are averaged. After the processing, a value obtained by multiplying the magnification of the pressure increase ratio is output to the display device 116 to display the pressure. Intensifier 1
02 piston 108 approaches the end of stroke and detector 109 or 11
When 0 is activated, the immediately preceding display pressure is displayed as it is, and after a predetermined time, for example, 0.5 seconds or 1 second, the pressure based on the sampling and averaging process by the above method is displayed again.

The following table shows measured values obtained by comparing the conventional method shown in FIG. 4 with the method of the present invention under the same conditions.

As can be seen from these results, the accuracy of the displayed pressure was improved near the maximum rated output.

[Effects of the Invention] As described above in detail based on the embodiments, the present invention uses the hydraulic pressure when displaying the pressure of the reciprocating pump configured to discharge the secondary liquid by reciprocally driving the pressure intensifier by the hydraulic pressure. A pressure detector provided in the pipeline, a stroke end detector of a piston of the pressure intensifier, a calculation device for calculating and processing a detection value of each detector, and a display device for displaying a calculation result in the calculation device, When the detection signal is output from the stroke end detector of the pressure intensifier, the value before the signal output is displayed on the display for a predetermined time from the output of the signal, and otherwise, the detection value of the pressure detector is detected by the arithmetic unit. Since the average detected value within the predetermined time is calculated and the value based on the average detected value is displayed on the display, the error between the displayed pressure and the actual pressure of the discharge pipe is small, and Shows realistic pressure This makes it possible to improve the reliability of the device.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a pump device to which the present invention is applied, FIG. 2 is a waveform diagram showing a relationship between a pressure fluctuation and a signal in the present invention, and FIG. 3 is an enlarged view of a main part of FIG. FIG. 4 is a diagram showing a pressure detection waveform according to a conventional method. 100: Hydraulic pump, 101: Hydraulic line 102: Booster, 107: Direction control valve 108: Piston, 109, 110: Stroke end detector 111: Pressure detector, 112: Nozzle 115: Computing device, 116: Display device

Claims (1)

(57) [Claims] 1. A reciprocating pump in which a pressure intensifier is reciprocally driven to discharge a secondary liquid by a hydraulic pressure, a pressure detector provided in a hydraulic line, a stroke end detector of a piston of the pressure intensifier, An arithmetic unit for arithmetically processing the detection value of each detector;
A display device for displaying a calculation result in the calculation device, wherein when the detection signal is output from the stroke end detector of the pressure intensifier, the value before the signal output is displayed on the display for a predetermined time from the signal output time. Other than that, a pressure display method in which an arithmetic device calculates an average detected value of the pressure detector within a predetermined time and displays a value based on the average detected value on a display.