JPH09264261A - Liquid pressurizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid pressurizing device stably jetting high pressure liquid without any pulsation. SOLUTION: Plunger pumps 120, 130 suck and pressurize the liquid fed from a liquid feeding unit 110 so as to alternately discharge it to the outside via a jetting unit 150. A control unit 140 controls servomotors 121, 131 driving plungers 122, 132. When the plunger pump 120 is in a delivery stroke, the plunger pump 130 is on standby while pressurized to a pressure slightly lower than the delivery pressure. When the delivery stroke of the plunger pump 120 is finished, the plunger pump 130 is pressurized to the delivery pressure, and then, moved to the discharge stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid pressurizing device using a reciprocating pump such as a plunger pump.

[0002]

2. Description of the Related Art When a high-pressure liquid is used for cutting a material or pressurizing a pressure vessel, a liquid-pressure booster type high-pressure pump in which the low-pressure side is hydraulic and the high-pressure side is water is used as a liquid pressurizing source. The one in which two units are arranged in parallel is used. In such a parallel arrangement, the two high-pressure pumps are alternately operated to discharge the high-pressure liquid, and therefore, even when the liquid discharge changes from one booster to the other booster even under steady operating conditions. Almost periodic pressure fluctuations (pulsations) occur, which makes the cut surface uneven, especially in the case of water jet cutting.
In some cases, the quality of the product deteriorated.

Conventionally, in order to reduce this pulsation, a detector such as a limit switch is provided at a position immediately before the pressure booster reaches the forward end, and the position of the pressure booster is detected by the detector of one pressure booster. Then, the other pressure booster is activated to move it forward,
A method (pre-start method) was used to switch the booster to discharge when the pressure exceeded.

A detailed description will be given with reference to FIG. 6A showing the pressure change. Since pressure boosters A and B are provided and the high pressure liquid is discharged by alternately switching the pressure boosters having a high pressure, the pressure of the discharged liquid to the outside is higher than that of either one of them. It becomes pressure (synthesis).

[0005]

However, in this pre-start method, the magnitude of pulsation is influenced by the plunger speed, and the plunger speed fluctuates due to various factors as long as it is the hydraulic drive method. For example, the plunger speed fluctuates and pulsation occurs due to changes in the set pressure and discharge flow rate, changes in the temperature of the working liquid at the time of startup or after a certain period of time, and other leaks in the high pressure portion.

That is, conventionally, since only the position of the plunger in operation is detected to control the timing of the operation of the other plunger, the fluctuation of the plunger speed is not a factor for determining the timing of operation, and it is detected. There is an inconvenience that the plunger speed at which the pulsation becomes small is determined by the position where the container is provided.

For example, as shown in FIG. 6 (b), when the plunger speed of the pressure booster A becomes faster, the time required to reach the forward end is shorter than usual, so the discharge pressure drops faster than usual. On the other hand, the timing for activating the pressure booster B is based on the information from the position detector, and is the same as the normal time. As a result, the timing for activating the pressure booster B is delayed,
The pulsation increases.

In order to avoid this situation and to suppress pulsation as much as possible and to obtain stable injection of high-pressure liquid, various proposals have been made to deal with the mounting of the accumulator, but only using the accumulator. Then, about 10% of the whole pulsating flow remained, and satisfactory results were not obtained.

Besides, in order to avoid such a situation, it is necessary to take an extra overlap portion, and the control system becomes unstable. Furthermore,
Eliminating pulsation by controlling the pressure of the hydraulic fluid is currently in practical use, but it is necessary to configure a complicated hydraulic circuit to adopt a hydraulic servo valve or solenoid proportional valve. However, it is difficult to maintain the optimum conditions, and the cost required for them cannot be ignored.

As the drive source of the plunger, there is an electric type in addition to the hydraulic type. For example, Japanese Utility Model Application Laid-Open No. 1-76570 discloses a pair of reciprocating pressure boosters that generate a high-pressure water jet used for material cutting as a liquid pressurizing device using an electric double-acting booster. In order to reduce the pulsation that occurs when the reciprocating motion is switched based on the compressibility of the liquid due to the increase in pressure, the encoder of the position control system built into the servo motor allows the servo motor to operate until the liquid reaches a predetermined pressure. It has also been shown to shorten the compression time by increasing the rotation speed of, but to eliminate pulsation almost in any case,
This method also has its limits.

The present invention has been made to solve the above problems, and an object thereof is to provide a liquid pressurizing device which does not generate pulsation even when the pressure of the discharged liquid is changed. Another object is to provide a liquid pressurizing device that can be easily controlled to maintain no pulsation. Further, it is another object of the present invention to provide a liquid pressurizing device that can flexibly and finely perform control for maintaining no pulsation.

[0012]

In the invention described in claim 1, first and second reciprocating pump means for pressurizing the sucked liquid and alternately discharging the liquid, and the first and second reciprocating pump means. First and second pressure measuring units, which are respectively provided in the dynamic pump means and measure the pressure of the high-pressure liquid and output it as a signal, and the first reciprocating pump means for pressurizing, the first pressure measuring unit When receiving a signal of a predetermined first pressure value from, the liquid of the first reciprocating pump means is discharged,
The second reciprocating pump means pressurizes the sucked liquid until the signal of a predetermined second pressure value that is slightly smaller than the first pressure value is received from the second pressure measurement unit. And a control means for maintaining the state and discharging the pre-pressurized liquid when the pressure of the liquid discharged from the first reciprocating pump means becomes lower than the pre-pressurized liquid of the second reciprocating pump means.

The first reciprocating pump means is provided with a first pressure measuring section, and the second reciprocating pump means is provided with a second pressure measuring section. The pressures of the pressurized liquids of the first and second reciprocating pump means are measured by the first and second pressure measuring units, and are output to the control means as signals. Therefore, the control means can control the timing of suction, pressurization and discharge of the first and second reciprocating pump means based on this signal.

The first reciprocating pump means performs the pressurizing operation under the control of the control means until it receives the signal of the first pressure value from the first pressure measuring section. Here, the first pressure value is the pressure value of the high-pressure liquid to be discharged to the outside, and when receiving the signal, the control means causes the first reciprocating pump means to discharge the high-pressure liquid. Therefore, the pressure of the discharged liquid can be controlled with high accuracy.

In parallel with the discharge process of the first reciprocating pump means, the control means causes the second reciprocating pump means to suck the liquid, and then the second pressure measuring section measures the second pressure value. Pressurize until signal is received. Then, when receiving this signal, the second reciprocating pump means is controlled so that the pressure value of the pressurized liquid of the second reciprocating pump means holds the second pressure value. The pressure state at this time is measured by the second pressure measuring unit, and the measurement result is output as a signal to the control means.

Since the second pressure value is slightly smaller than the first pressure value as described above, the second reciprocating pump is started after the liquid discharged from the first reciprocating pump means starts to decrease. Even if the means is pressurized to the first pressure value, it can be pressurized to the first pressure value in a very short time.

At the end of the discharge process of the first reciprocating pump means, the pressure of the high-pressure liquid being discharged begins to drop, and when the signal of the second pressure value is received from the first pressure measuring unit, the control is performed. The means pressurizes the second reciprocating pump means to bring the high pressure liquid held at the second pressure value to the first pressure value. Then, when the signal of the first pressure value is received from the second pressure measuring unit, the second reciprocating pump means is caused to discharge the high-pressure liquid to the outside instead of the first reciprocating pump means.

By repeating such control, the high pressure liquid between the first pressure value and the second pressure value is alternately discharged from the first and second reciprocating pump means to the outside. Is.

Here, since the difference between the first pressure value and the second pressure value is small, pressurization for an extremely short time is sufficient.
Further, since the respective pressure values are grasped by the control means by the signal from the pressure measuring unit, the difference (pulsation) can be predicted in advance, and the pulsation control amount which does not affect the pressure fluctuation due to the use situation can be obtained. It is possible to eliminate the pulsation of the discharged liquid to the outside.

The first pressure measuring section is for measuring the pressure of the liquid in the first reciprocating pump means in the pressurized state, the standby state and the discharged state, and the second pressure measuring section. Is for measuring the pressure of the liquid in the second reciprocating pump means in the pressurized state, the standby state, and the discharged state. One pressure measuring device is used as each of the first and second pressure measuring units. The invention is not limited to the case of providing each one, and a plurality of cases may be provided. For example, each of the first and second pressure measuring units may be composed of a pressure measuring device that measures the pressure in the pressurized state and the standby state and a pressure measuring device that measures the pressure in the discharge state. Further, a pressure measuring device for measuring the pressure in the discharge state by the first reciprocating pump means and a pressure measuring device for measuring the pressure in the discharge state by the second reciprocating pump means are provided.
It may be configured with one pressure measuring device.

In the invention described in claim 2, claim 1
In the invention described in (1), the first and second reciprocating pump means are plunger pumps, and each of them has a servomotor controlled by the control means as a drive source thereof.

That is, in this case, the liquid is pressurized to a predetermined pressure value by the plunger pump, and the plunger pump is driven by the servo motor, so that the stroke of the plunger of the plunger pump can be controlled on the servo motor side. Here, since the position of the plunger (the position near the forward end) at which the pressure drops to the second pressure value in the discharge state can be predicted, if that position is set in advance and input to the control means, the discharge by the position servo is performed. Soft limit of pressure is possible. That is, the timing of pressurizing the plunger pump on the stand-by side to the first pressure value is not controlled based on the signal of the discharge pressure from the pressure measurement unit, but the plunger stroke of the servo motor characteristic is utilized. It can be performed based on the position of the plunger, such as numerical control. Therefore, the structure of the device is simplified, control by the control means is facilitated, and the discharge of the high-pressure liquid to the outside is stabilized.

In the invention described in claim 3, claim 2
In the invention described in (1), the control means performs speed control in the discharge step of the plunger pump, and torque control (current control) in the preload holding step.

That is, in the plunger pump on the discharge (injection) side, by operating the plunger at a constant speed, it is possible to discharge at a predetermined pressure and hold (standby) the second pressure value. The plunger pump on the side can always generate a torque value commensurate with the required pressure. Therefore, since it is possible to respond to changes in the situation during use, flexible control is possible, and it is possible to respond to detailed requests.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a liquid pressurizing device according to an embodiment of the present invention. In the liquid pressurizing apparatus according to this embodiment, a nozzle device for material cutting by high pressure liquid injection is shown, but the food in a pressure vessel for pressurizing food of a constant volume to which the high pressure liquid is supplied is added. It may be a device for pressure treatment.

FIG. 1 is a hydraulic circuit diagram. This liquid pressurizing device includes a liquid supply section 110, a plunger pump 120 as a first reciprocating pump means, and a plunger pump 130 as a second reciprocating pump means. , A control unit 140 as a control unit, and an injection unit 150.

The liquid supply section 110 is provided with a plunger pump 120.
It is for supplying a liquid to 130, and includes a pressure medium tank 111, a liquid supply pump 112, a pressure sensor 113, and a relief valve 114.

The liquid in the pressure medium tank 111 is sent to the plunger pumps 120 and 130 and pressurized, and then the injection unit 1
It is injected from 50 to the outside. Therefore, the type of liquid can be appropriately selected depending on the case where the liquid is used for material cutting or the pressure treatment of food.

The liquid supply pump 112 is for sending this liquid to the plunger pumps 120 and 130 at a predetermined pressure, and may be a rotary pump or a reciprocating pump that can continuously supply the liquid. The pressure of the supplied liquid is grasped by the pressure sensor 113, and when the pressure becomes equal to or higher than a predetermined pressure, the relief valve 114 is opened and the excess liquid is discharged to the pressure medium tank 111.
The supply pressure of the liquid supplied to the 20/130 via the check valve is maintained below the set pressure of the relief valve 114. As a result, the liquid supply unit 110 and each plunger pump 1
The check valve between 20 and 130 will not open carelessly. It is also possible to allow the plunger pumps 120 and 130 to self-suction the liquid in the pressure medium tank 111 without providing the liquid supply pump 112.

The plunger pumps 120 and 130 are arranged in parallel on the hydraulic circuit. Also, the configurations of both may be the same, and the servo motors 121, 131,
And the plungers 122 and 132 driven by these servomotors. Plunger 122/132
By moving in the direction of the arrow A shown in the drawing,
Liquid is sucked into 23.133 (inhalation process), and arrow B is reversed.
By moving in the direction, the liquid sucked in the suction step is pressurized and discharged (discharge step).

Here, in this embodiment, since the plunger pump and the servo motor are adopted, the control becomes easy. On the other hand, although the plunger pumps 120 and 130 are of single-acting type, they may be of double-acting type instead, in which case the discharge flow rate can be increased. Further, the servo motors 121 and 131 may be DC motors or AC motors, but DC motors have a large torque.
A DC motor is preferably used because the rotation can be smoothly adjusted. Although the servomotors 121 and 131 are used as the drive source of the plunger pump, a hydraulic motor may be used instead.

The plunger pumps 120 and 130 alternately discharge the high-pressure liquid to the injection unit 150. The timing of the suction process and the discharge process of the plungers 122 and 132 is the control unit that controls the servomotors 121 and 131. Determined by 140. The determination is made from the pressure sensor 124 that measures the discharge pressure of the plunger pump 120, the pressure sensor 134 that measures the discharge pressure of the plunger pump 130, and the pressure sensor 151 that measures the injection pressure of the injection unit 150 described below, respectively. This is performed based on the signal input to 140.

The pressure sensor 124 constitutes a part of the first pressure measuring section, and the pressure sensor 134 constitutes a part of the second pressure measuring section. The pressure sensors 124 and 134 both set pressure P ₁ as the first pressure value and set pressure P ₂ as the second pressure value.
To monitor and measure.

Check valves 125 and 135 are provided on the liquid supply section 110 side (upstream section) of the flow path connected to the plunger pumps 120 and 130, and further, on the injection section 150 side (downstream section), Check valve 126
-136 is provided. Check valve 125/135
Is from the liquid supply unit 110 to the plunger pump 120/130.
Allowing only liquid to flow into the check valve 126.13
6 is the injection unit 15 from the plunger pump 120/130.
Only allow liquid to flow to zero. Both are arranged so as to prevent a reverse flow from the downstream side to the upstream side.

The high-pressure liquid from the plunger pumps 120 and 130 passes through the check valves 126 and 136, and the injection unit 1
Sent to 50. The injection unit 150 includes a pressure sensor 151,
It is composed of a filter 152, a stop valve 153 and a nozzle 154.

The pressure sensor 151 measures the pressures P ₁ and P ₂ of the high-pressure liquid alternately discharged from the two plunger pumps 120 and 130, and the measurement result is input to the control unit 140 as an electric signal. To be done. In this embodiment, the pressure sensor 151 constitutes a part of the first pressure measuring section and also constitutes a part of the second pressure measuring section.

The filter 152 is for removing fine dust and the like in the high-pressure liquid, whereby the nozzle 1
The clogging of 54 can be prevented. Also, the stop valve 15
By opening and closing 3, it is possible to prevent the high-pressure liquid from being inadvertently ejected from the nozzle 154.

Next, the controller 140 causes the plunger pump 1 to
How to control the 20/130 will be described. Now, it is assumed that the upper limit set value of the pulsation of the injection pressure in the injection unit 150 is P ₁ and the lower limit set value is P ₂ slightly lower than P ₁ . Moreover, from the plunger pump 120 is the set pressure P ₁ at the discharge high pressure liquid check valve 126 of the set pressure P ₁ In the midst of the process is supplied to the ejection unit 150, ends the other plunger pump 130 is a suction stroke It is assumed that it is in a state where At this time, the control unit 140 controls the pressure sensor 1
Plunger pump 1 based on the signal input from 24
It is judged that the pressure of the pump chamber 123 of 20 has reached the set pressure P ₁ , and on this condition, the plunger pump 120
A signal to the servo motor 121 to discharge the pressurized liquid in the pump chamber 123 of the
2 is moving in the direction of arrow B. The high-pressure liquid discharged from the pump chamber 123 pushes the check valve 126 open, flows out to the injection unit 150, and is ejected from the nozzle 154 through the stop valve 153 in the opened state (ejection process). The pressure of the discharged liquid in this case is maintained at the set pressure P ₁ by the control of the servo motor 121 by the control unit 140.

During the discharge process of the plunger pump 120, the controller 140 pressurizes the liquid sucked into the pump chamber 133 of the plunger pump 130 until the signal of the set pressure P ₂ is obtained from the pressure sensor 134. The plunger pump 130 is caused to perform a pressurizing operation. Pressure sensor 1
When the pressure measurement signal input from 34 to the control unit 140 reaches the set pressure P ₂ , the control unit 140 controls the pressurized liquid in the pump chamber 133 of the plunger pump 130 to be kept at the set pressure P _2. , And controls the operation of the servo motor 131 (standby process).

Here, when one of the plunger pumps is in the discharge process (when the device is operating), the plunger speed of the other plunger pump in the suction process is
It is necessary to control so as to be higher than the plunger speed of the plunger pump in the discharge process. This is to ensure that the time obtained by adding the time required for the suction process and the time for the standby process is less than the time for the discharge process.

This state will be described with reference to FIG. In FIG. 2, at the time of the above-described operation, what is ejected from the nozzle 254 is the high-pressure liquid having the pressure P ₁ from the plunger pump 220, and the other plunger pump 230 is not ejecting the high-pressure liquid. That is, the plunger pump 230
The plunger pump 220 waits until just before it finishes discharging the high-pressure liquid of pressure P ₁ . The check valve 226
Since the upstream side P ₁ > the downstream side P _2, it is pushed open by the discharge pressure P ₁ from the pump chamber 223 to supply the high pressure liquid to the downstream nozzle 254, but the other check valve 236.
Is closed because the upstream side P ₂ <the downstream side P ₁ , and the high pressure liquid held at the pressure P ₂ in the pump chamber 233 is in a state in which the downstream flow is blocked.

[0042] Here, the pressure P ₂ is set to be slightly lower pressure value than the pressure P _1, for example, when the pressure P ₁ is to 100 MPa, the pressure P ₂ is 98MPa
Although it is selected to some extent, these set values P ₁ and P ₂ may be appropriately determined in accordance with the application and usage situation of the device.

Thus, one plunger pump 22
When 0 is in the discharge step, the operation of the standby step is performed in the other plunger pump 230 in order to pressurize the liquid in the pump chamber 233 to a pressure P ₂ which is extremely close to the discharge pressure P ₁ and hold it in advance. Therefore,
The subsequent pressurization of the liquid having the pressure P ₂ to the discharge pressure P ₁ can be performed within a very short time with a small operation stroke of the servo motor.

As the amount of discharge from the pump chamber 223 decreases as the plunger 222 reaches the forward end, the discharge pressure gradually decreases from P ₁ , and at the same time it becomes the pressure P ₂ , the check valve 226 moves the upstream side P ₂ = Since it is on the downstream side P ₂ , it is closed by a cracking spring, and the pump chamber 223
The supply flow of high-pressure liquid from is cut off. At this time, the control unit 140 detects that the supply pressure has dropped to P ₂ based on the measurement signal given from the pressure sensor 251, and at the same time sends a signal to the servo motor to send a signal to the plunger 23.
2 is moved forward, and the liquid in the pump chamber 233 is moved to P
Immediately pressurize to ₂ or more and immediately discharge.

In this case, the fact that the discharge pressure of the plunger pump 220 has dropped to P ₂ may be detected by the measurement signal from the pressure sensor 224. Even in this case,
The pressure sensor 251 can grasp the actual state of the pressure of the discharged liquid to the outside, and can confirm the presence or absence and the degree of pulsation.

Further, the timing for starting the advance of the plunger 232 is controlled not based on the signal from the pressure sensor as described above but based on the detection signal of the plunger position of the plunger pump at the end of the discharge process. May be. This is a so-called soft limit system, and the discharge pressure can be controlled by using the position servo control of the servo motor to numerically set the operation stroke of the plunger and position control. Also in the embodiment shown here, the plunger pump having the plunger that moves linearly is driven by the position controllable servomotor, so that the discharge pressure, which was P ₁ in each pressurizing device, drops to P _2. The position of the plunger can be known in advance as unique position information. Therefore, by numerically inputting the position into the control unit 140 in advance and numerically controlling the servomotor by the position servo, the plunger in the standby state is controlled by the control unit 140. The timing at which the pump enters the discharge process can be determined and controlled.

FIG. 3 shows a state where one plunger pump has reached the end of the discharge process and then the other plunger pump has entered the discharge process from the standby state. In the plunger pump 330 that has entered the discharge process from the standby state, the high-pressure liquid in the pump chamber 333 rises from the pressure P ₂ to P ₁ , and this high-pressure liquid pushes the check valve 336 open to open the nozzle 3
Ejected from 54. On the other hand, in the meantime, in the plunger pump 320 that has completed the discharge process, the check valve 325
From the above, a suction process of sucking the liquid in the pressure medium tank into the pump chamber 323 is performed, a pressurization process up to the pressure P ₂ is performed immediately after the suction is completed, and the standby process is started at the pressure P ₂ . Hereinafter, this control is repeated, and the two plunger pumps alternately perform the same operation.

According to this embodiment, since the discharge of the high-pressure liquid is controlled by the measured pressure in the system, the liquid pressurizing device can be designed so that the pulsating flow does not affect the use condition. Also, according to this method, the timing of pressure drop can be predicted in advance, so the servo motor of the other plunger pump in the standby process is slightly before the plunger of one plunger pump in the discharge process reaches the forward end. The pulsation pressure drop amount can be further reduced by activating and moving the plunger forward. In this way, a substantially continuous injection is possible,
Moreover, the pulsating flow is very small, even if it does not exist. Therefore, high-pressure injection with almost no pulsation is possible, and for example, it is possible to complete a homogeneous product in the emulsification / fine particle manufacturing field.

Next, the manner in which the pressure of each part changes in the case of the above embodiment will be described with reference to FIG. When the plunger pump A is in the discharge process, the injection pressure is P ₁ (time points 501 and 502). At this time, the plunger pump B sucks the liquid from the liquid supply portion (time point 501), pre-pressurizes to P ₂ after the suction, and stands by (time point 50).
2). Then, the discharge pressure of the plunger pump A starts to drop (time point 503), and when it drops to the pressure P ₂ , the plunger pump B slightly pressurizes the liquid in the pump chamber from the pressure P ₂ to P ₁ , Move to the discharge process.
Thereafter, such control is repeated, and both plunger pumps alternately discharge the high-pressure liquid.

That is, the injection pressure is changed from the time points 503 to 504.
Minute pulsation with pressure drop (P ₁ -P ₂ ) occurs, but the standby pressure P ₂ is set and the pressurization start timing from the standby pressure P ₂ to the discharge pressure P ₁ is advanced. As a result, the pulsation can be made extremely small.

Next, the schematic structure of the control system of the servo motor in this embodiment will be described with reference to the block diagram shown in FIG. Note that the control units 401 and 411 shown here
Is a part of the control unit 140 in FIG. Further, the servo amplifiers 403 and 413 and the servo motors 404 and 414 are the servo motor 121 in FIG.
-It constitutes 131.

(A) is for controlling the speed of the servomotor, and is for a plunger pump on the injection side which requires the plunger to move forward at a constant speed. This is because if the plunger is advanced at a constant speed, the high-pressure liquid having the pressure P ₁ can be discharged.

(B) is for controlling the torque of the servomotor, and is for a plunger pump on the standby side which is required to constantly generate a torque value commensurate with the pressure P ₂ . This is because the pressure of the liquid can be kept at P ₂ by holding the plunger at the same position when the leakage is zero while waiting.

First, (a) will be described. When the injection pressure is set by the setting device 401 when the liquid pressurizing device is used, this is given to the control unit 402 as a signal. A measurement signal of a pressure sensor 406 that measures the discharge pressure of the pump 405 is also input to the control unit 402. The control unit 402 compares both the set pressure and the measured pressure, calculates the required speed of the plunger based on the comparison, and outputs the speed command to the servo amplifier 403. The servo amplifier 403 operates according to the speed command and outputs the servo motor 40.
4 is speed controlled, and the operating speed of the servo motor is fed back to the servo amplifier 403.

The servo motor 404 operates the plunger pump 405 based on the speed command to move the plunger forward. The discharge pressure at this time is determined by the pressure sensor 406.
Is constantly measured and sent to the control unit 402 for pressure feedback. In this way, the control unit constantly compares the set pressure with the actual pressure fed back to give a speed command to the servo amplifier.Furthermore, since speed feedback is also applied to the servo amplifier, minor feedback of speed is performed. Is realized with high accuracy, and the pump 405 performs the discharge operation in which the discharge pressure is kept constant at the set pressure.

Next, (b) will be described. The setting device 411 in this case sets the standby pressure, and the set value of the standby pressure is given to the control unit 412 as a signal. The control unit 412 is also provided with a measurement signal of the pressure sensor 415 that measures the discharge pressure of the pump 415. The control unit 412 compares these signals, calculates the required torque value of the servo motor 414 based on the signals,
A torque command is output to the servo amplifier 413. The servo amplifier 413 uses the servo motor 41 according to the torque command.
4 is torque-controlled, and the load current of the servo motor 414 is fed back to the servo amplifier 413.

The servomotor 414 operates the plunger pump 405 based on the torque command to move the plunger forward and backward. The standby pressure in the pump chamber at this time is constantly measured by the pressure sensor 416 and sent to the control unit 412 to perform pressure feedback. In this way, the control unit constantly compares the set standby pressure with the actual feedback pressure fed back to issue a torque command to the servo amplifier. Furthermore, since torque feedback is also applied to the servo amplifier, the torque Pressure control including minor feedback is realized with high accuracy,
The pump 415 performs a preload (standby pressure) control operation in which the standby pressure is kept constant at the set standby pressure.

[0058]

According to the invention described in claim 1, even when the reciprocating pump means arranged in parallel is switched,
Since it is possible to suppress the pressure fluctuation of the high-pressure liquid that is ejected to the outside of the device, it is possible to ensure stable ejection of the high-pressure liquid with almost no pulsation.

According to the invention described in claim 2, since the structure is simplified and the control thereof is facilitated, further stabilization of the pressure can be secured.

According to the invention described in claim 3, since highly accurate control is possible, it is possible to cope with a change in the situation when the present apparatus is used, and it is possible to perform flexible control and perform fine control. be able to.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram showing a configuration of a liquid pressurizing device according to an embodiment of the present invention.

FIG. 2 is a schematic circuit diagram partially showing a configuration of a liquid pressurizing device according to an embodiment of the present invention.

FIG. 3 is a schematic circuit diagram partially showing a configuration of a liquid pressurizing device according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of a servo motor control system according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a pressure state of the liquid pressurizing device according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a pressure state of the liquid pressurizing device according to the embodiment of the present invention.

[Explanation of symbols]

 110 ··· Liquid supply unit 111 ··· Liquid medium tank 112 ··· Liquid supply pump 113 ··· Pressure sensor 113 ··· Relief valve 120, 130 ··· Plunger pump 121, 131 · · Servo motor 122, 132 · · Plunger 123, 133 · · Pump chamber 124, 134 · · Pressure sensor 125, 135 · · Check valve 126, 136 · · Check valve 140 ...・ ・ ・ Control unit 150 ・ ・ ・ ・ ・ ・ Injection unit 151 ・ ・ ・ ・ ・ ・ Pressure sensor 152 ・ ・ ・ ・ Filter 153 ・ ・ ・ ・ Stop valve 154 ・ ・ ・ ・ ・ ・ Nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Sugimori 2410 Motoe, Uozu City, Toyama Prefecture Sugino Mashin Co., Ltd.

Claims (3)

[Claims] 1. A first and a second reciprocating pump means for pressurizing the sucked liquid and alternately discharging the same, and a first and a second reciprocating pump means respectively provided for controlling the pressure of the high-pressure liquid. The first and second pressure measuring units that measure and output as signals, and the first reciprocating pump means that is pressurizing, receive a signal of a predetermined first pressure value from the first pressure measuring unit. The liquid of the first reciprocating pump means is discharged, and the liquid sucked in the second reciprocating pump means is slightly smaller than the first pressure value and a predetermined second pressure value. The pressure of the liquid discharged from the first reciprocating pump means becomes lower than that of the pre-pressurized liquid of the second reciprocating pump means until the pressure is maintained until the signal is received from the second pressure measuring unit. And a control means for discharging the pre-pressurized liquid. Liquid pressure device, characterized in that. 2. The liquid according to claim 1, wherein the first and second reciprocating pump means are plunger pumps, and each of them has a servomotor controlled by the control means as a drive source thereof. Pressurizing device. 3. The liquid pressurizing device according to claim 2, wherein the control means performs speed control in the discharge step of the plunger pump, and torque control (current control) in the preload holding step.