JPH0543478B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control circuit for a double-acting or single-acting fluid-pressure-driven reciprocating pump, and more specifically, a control circuit for controlling a primary fluid that is a pump-driving fluid. In particular, this invention relates to an improvement in the circuit configuration for controlling the rate of pressure rise and fall of a water jet, which is a secondary fluid.

[Prior Art] Reciprocating pumps include those that force the piston to reciprocate using a rotational drive means such as a crankshaft, those that reciprocate the piston using fluid pressure, and those that use a combination of the above two methods. and so on. On the other hand, in terms of operation, there are single-acting types that perform a pumping action in only one stroke of the reciprocating motion and only idle movement in the other stroke, and double-acting types that perform a pumping action in both the forward and backward strokes. It is classified into expressions.

A double-acting pump that uses fluid pressure to reciprocate a piston generally drives a large-diameter piston with relatively low fluid pressure, and performs the pumping action with a small-diameter piston that extends from the large-diameter piston. It is often used in so-called pressure booster pumps. In particular, it is used in high-pressure water generators for water jet cutting equipment, the demand for which has been increasing in recent years, and is effectively put into practical use as a pump that continuously generates ultra-high pressure water of several hundred MPa.

FIG. 5 shows a schematic circuit diagram of a general reciprocating pump. That is, in the figure, the supply direction of the hydraulic oil pressurized by the hydraulic pump 27 is controlled by the direction control valve 7, and the supply direction is controlled by the direction control valve 7.
8. In the illustrated case, the hydraulic oil in the low pressure chamber 5 is pressurized by being supplied to the supply port 17 and presses the low pressure piston 1 to the right in the figure. High pressure piston 1
1 and 12 extend integrally with the low-pressure piston 1, so when the low-pressure piston 1 moves to the right, the high-pressure piston 11 also moves to the right, reducing the pressure inside the high-pressure cylinder 13, and as a result, the suction pipe 31, the water in the water tank 38 is introduced into the high pressure cylinder 13 through the check valve 35. On the other hand, the high pressure piston 12 moves to the right and pressurizes the water in the high pressure cylinder 14.
The pressurized water passes through a check valve 34 to a high pressure pipe 32.
The liquid is then injected from the nozzle 37. In this way, when the low pressure piston 1 moves to the right together with the high pressure pistons 11 and 12 and approaches the right end surface 4 of the low pressure cylinder 2 and reaches the stroke end, the detection device 26 is activated.
The signal from the detection device 26 is transmitted to the direction control valve 7 via the signal line 30.
is transmitted to switch the directional control valve 7 to a position opposite to that shown in the figure. Then, the moving direction of the low pressure piston 1 and the high pressure pistons 11, 12, which had been moving rightward until then, is switched and moved to the left, with the high pressure piston 11 being in the discharge stroke and the high pressure piston 12 being in the suction stroke. When the low pressure piston 1 approaches the left end surface 3 of the low pressure cylinder 2 and reaches the end of its stroke, the detection device 2
5 is activated, a signal from the detection device 25 is transmitted to the directional control valve 7 via the signal line 29, and the directional control valve 7 is again switched to the illustrated position. As a result, the low pressure piston 1 is urged to move rightward in the figure, and
The high pressure piston 11 is in the suction stroke, the high pressure piston 12
will perform a discharge stroke.

The pump action is achieved by repeating this operation.

[Problems to be Solved by the Invention] In recent years, ultra-high pressure water pressurized by the fluid pressure-driven reciprocating pump has become widely used in the field of application. There is peeling and cleaning using an ultra-high pressure jet.

In this process of stripping and cleaning, there are many cases where the actual work location and the pump installation location are relatively far apart, so flexible piping such as a hose is used to connect the pump and the actual work location. Common.
When controlling the injection and stopping of ultra-high pressure water (hereinafter referred to as secondary liquid) from the nozzle during the execution and stopping of work, pressurized pump driving liquid (generally oil; hereinafter referred to as primary liquid) is used. ) is controlled by supplying and stopping the pressure booster, which is a pump device.

That is, as shown in FIG. 5, conventionally, a solenoid valve 55 and a remote control relief valve 58 have been provided to control the relief valve 50. That is,
As shown, when the solenoid valve 55 is in the open state, the relief valve 50 operates at a very low pressure and discharges the primary liquid to the tank 39, so that the primary liquid line 53 is maintained at a low pressure and the pressure intensifier 40 is activated. It cannot be activated and the secondary liquid is not discharged. vice versa,
When the solenoid valve 55 is closed, the relief valve 50 operates at a pressure proportional to the pressure in the remote control line 51 adjusted by the remote control relief valve 58, and the pressure in the primary liquid line 53 rises and increases. The pressure machine 40 is operated. Generally, the remote control relief valve 58 is operated only for pressure adjustment, and the opening and closing of the electromagnetic valve 55 is used to control discharge and stop of the secondary liquid.

By the way, in FIG. 5, when the solenoid valve 55 is closed in an attempt to discharge the secondary liquid, the primary liquid is suddenly supplied to the pressure intensifier 40, and as a result, the pressure of the secondary liquid increases rapidly. Become.
Conversely, when attempting to stop the discharge of the secondary liquid, the solenoid valve 5
When 5 is released, the pressure of the secondary liquid drops rapidly. Therefore, if the discharge and stop of the secondary liquid is frequently repeated due to work reasons, a pressure difference of several hundred MPa to OMPa will rapidly and repeatedly act on the secondary liquid pipe each time. Here, as mentioned above, the pump and the actual working position are connected by hoses, etc., but flexible piping members such as hoses are more resistant to sudden pressure fluctuations than other pump parts or steel pipe parts. The strength is extremely low, and there is a risk of rupture. At the same time, when a hand-held nozzle device is used during work, the reaction force exerted on the worker by the secondary liquid jetted from the nozzle changes rapidly, making the work extremely dangerous.

[Means for Solving the Problems] The present invention was made in view of the above-mentioned current situation, and its purpose is to alleviate rapid fluctuations in pressure acting on the secondary liquid piping system, In addition to extending the life of flexible piping members such as motsute hoses,
The purpose is to alleviate sudden fluctuations in the spray reaction force that acts on the worker when using a hand-held nozzle, etc., so that the worker can work safely.

In order to achieve such an object, the present invention has the following configuration. In other words, in a hydraulically driven reciprocating pump, a pressure accumulator is provided that communicates with the primary liquid relief valve through a throttle valve in the same pipeline, and a pressure accumulator that communicates with the primary liquid relief valve via a throttle valve. The configuration is characterized in that a pressure accumulator is provided and a shutoff valve is disposed between the pipe line and the throttle valve.

[Function] In the above configuration, when the solenoid valve 55 is activated and shifts to the closed state, the pressure inside the remote control pipe 51 increases, but a part of the pressure rises in the pressure accumulator 54 disposed in the remote control pipe 51. Since the pressure inside the remote control conduit 51 does not rise rapidly, it rises gradually. As a result, the operating pressure of the relief valve 50 gradually increases. Since the pressure of the secondary liquid is set depending on the operating pressure of the relief valve 50, as a result of the above, the pressure of the secondary liquid gradually increases. At this time, if the resistance value R is inversely proportional to the opening degree of the throttle valve 57 that limits the flow rate of pressure oil flowing in and out of the pressure accumulator 54, and the volume of the pressure accumulator 54 is C, the solenoid valve 55 is closed and the remote control pipe 51 is closed. The time T required for the pressure to rise, the relief valve 50 to operate, and the pressure of the secondary liquid to rise to a predetermined pressure can be expressed as T=CR.

[Example] The present invention will be explained in more detail below based on the illustrated example.

FIG. 1 is a circuit diagram showing the basic configuration of the present invention, in which the conventional circuit configuration shown in FIG. 5 is replaced with the circuit shown in FIG. 1 downstream from the relief circuit 52 branched from the primary liquid conduit 53. This can be done by Now, the pressure oil, which is the primary liquid discharged from the hydraulic pump 27, is sent from the pipe 53 through the directional control valve 7 to the pressure booster 40 to drive the pressure booster 40. In the state shown in FIG. 1, the solenoid valve 55 is opened to the drain pipe 56, and the release control pressure of the relief valve 50 is a pressure as low as the pipe resistance. Therefore, the pressure in the pipe line 53 does not increase and the pressure intensifier 40 is not driven. That is, the pressure booster 40 does not discharge the secondary liquid. Next, in FIG. 1, when the solenoid valve 55 is switched to the closed state, the pressure in the remote control pipe 51 rises to the pressure set by the remote control relief valve 58, but when rising, the oil in the remote control pipe 51 is A part of it flows into the pressure accumulator 54 via the throttle valve 57. Therefore, the pressure within the remote control conduit 51 does not change suddenly but gradually increases. When the pressure in the remote control conduit 51 reaches the pressure set by the remote control relief valve 58, oil is relieved from the remote control relief valve 58 to maintain the pressure in the remote control conduit 51 at a predetermined pressure.
Since the relief setting pressure of the relief valve 50 depends on the pressure inside the remote control pipe 51, the relief valve 50
The relief setting pressure of 0 also rises, and as a result, the pressure in the pipe line 53 via the relief pipe line 52 rises, so that the pressure of the secondary liquid discharged from the pressure intensifier 40 rises. Conversely, when the solenoid valve 55 is released to the illustrated state in order to stop discharging the secondary liquid, the pressure within the remote control conduit 51 drops. At this time, contrary to the pressure increase, the oil in the pressure accumulator 54 flows out into the remote control pipe 51 through the throttle valve 57.
This prevents the pressure within the remote control conduit 51 from dropping rapidly. As a result, the relief setting pressure of the relief valve 50 gradually decreases, and the discharge pressure of the secondary liquid gradually decreases.

Here, when the pressure of the secondary liquid rises or falls, the rate of rise or fall is a resistance value R that is inversely proportional to the capacity C of the pressure accumulator 54 and the opening degree of the throttle valve 57.
If the time constant of the rise or fall is T, then the relationship T=CR is established, and by changing the capacity of the pressure accumulator 54 and the opening degree of the throttle valve 57, the time constant T, that is, the quadratic It is possible to change the rate of pressure rise and fall of the liquid. FIG. 4 illustrates this. That is, the pressure accumulator 5 as shown in FIG.
The characteristic of the conventional circuit configuration that does not include 4 is the curve shown by T=0 in the figure, and the predetermined pressure is reached in a short time. In other words, this indicates that the pressure increases rapidly. On the other hand, in the case of the circuit configuration according to the present invention, the curve is shown as T=CR or T'=C'R' in the figure, and the voltage gradually increases.

Incidentally, in the circuit configuration shown in FIG. 1, the relief valve 50
The remote investigation relief valve 58 and the pressure accumulator 54 act synergistically to cause a resonance phenomenon, which may cause the pressure control system to become unstable.

In order to prevent such a so-called hunting phenomenon, as shown in FIG. 2 or 3, a stop valve 60 that can shut off the primary liquid supplied to the pressure accumulator 54 is provided, The remote control conduit 51
The purpose can be effectively achieved by operating the pressure accumulator 54 near the set pressure and blocking the remote control liquid from entering and exiting the pressure accumulator 54 so that the pressure accumulator 54 does not operate. Here, blocking the flow of fluid into and out of the pressure accumulator 54 is equivalent to the conventional circuit shown in FIG. The set pressure is quickly reached near the pressure increase of the secondary liquid, and the overall pressure increase characteristic is the fourth.
It is clear that the characteristics roughly match the characteristics of T=CR or T'=C'R' shown in the figure, and do not deviate from the purpose of the present invention.

Various means can be used to operate the shutoff valve 60. A specific embodiment thereof is shown in FIGS. 2 and 3. FIG. 2 shows an example in which a sequence valve 59 is used, and a remote control pipe 51 is used.
The remotely controlled liquid from the sequence valve 59, which operates using the internal pressure as a pilot, acts as a pilot pressure for the shutoff valve 59, and operates the shutoff valve 60. That is, when the solenoid valve 55 is closed during pressure increase, the pressure within the remote control conduit 51 increases, but at this time the shutoff valve 60 is in the state shown. Therefore, the circuit is equivalent to that shown in FIG. As the pressure within the remote control conduit 51 increases, part of the liquid in the remote control conduit 51 flows into the pressure accumulator 54 to prevent the pressure within the remote control conduit 51 from rising rapidly. When the pressure is increased based on T=CR and the pressure in the remote control pipe 51 becomes close to the set pressure, the sequence valve 59 is operated by the pressure in the remote control pipe 51, and as a result, the shutoff valve 60 is operated. The connection between the remote control conduit 51 and the pressure accumulator 54 is cut off. After shutting off, the pressure in the remote control pipe 51 is directly applied to the relief valve 5.
It acts as a set pressure of 0 and determines the pressure in the pipe line 53. On the other hand, when the pressure decreases, when the solenoid valve 55 is returned to the state shown in the figure, the pressure in the remote control pipe 51 decreases, but the sequence valve 59 operates as the pressure decreases, supplying the pilot liquid to the shutoff valve 60. As a result, the shutoff valve 60 returns to the illustrated state and releases the liquid in the pressure accumulator 54 to the remote control conduit 51. Therefore, the pressure within the remote control conduit 51 does not drop suddenly but gradually. In FIG. 3, a pressure switch 61 is used as a means for operating the shutoff valve 60, and its function is the same as that of the sequence valve 59.

In either case, by slowing the pressure change in the remote control pipe 51, the pressure change of the secondary liquid injected from the nozzle 37 is slowed down, and the sudden change in the secondary liquid acting on the high-pressure pipe 32 is made slow. It is possible to prevent sudden pressure changes.

[Effects of the Invention] As described in detail above, in the present invention, in a hydraulically driven reciprocating pump in which a relief valve is provided in the pump driving liquid circuit, a throttle valve is provided in the same conduit as the relief valve. Furthermore, more specifically and practically, a pressure accumulator that communicates with the relief valve via a throttle valve is provided in the same pipe line as the relief valve, and a closed valve is provided between the pipe line and the throttle valve. Because it is equipped with a valve, there is no sudden change in pressure in the ultra-high pressure piping system.
In particular, it has the effect of extending the life of flexible piping such as hoses, and it also has the effect of allowing work to be carried out safely because the jet reaction force of the water jet does not fluctuate suddenly. It can be said that it is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a preferred embodiment of the present invention, FIGS. 2 and 3 are circuit diagrams showing other embodiments, and FIG. 4 is a comparison between a conventional device and a device of the present invention. The pressure fluctuation characteristic diagram shown in FIG. 5 is a diagram schematically representing a general hydraulically driven reciprocating pump. 7: Directional control valve, 27: Hydraulic pump, 40: Pressure booster, 50: Relief valve, 53: Primary liquid pipe line,
54: Pressure accumulator, 57: Throttle valve, 59: Hydraulic pilot valve, 60: Shutoff valve, 61: Pressure switch.

Claims (1)

[Scope of Claims] 1. A pump that is a hydraulically driven reciprocating pump and is provided with a relief valve in the pump driving liquid circuit, including a pressure accumulator that communicates with the relief valve through a variable throttle valve in the same pipe line. A control circuit for a water jet processing device, characterized in that: 2. In a pump that is a hydraulically driven reciprocating pump and is provided with a relief valve in the pump driving liquid circuit, a pressure accumulator is provided in the same pipe line as the relief valve and communicates with the pipe line via a variable throttle valve. A control circuit for a water jet processing device, characterized in that a shutoff valve is disposed between a throttle valve and a stop valve. 4. A control circuit for a water jet processing device according to claim 1, wherein the shutoff valve is a hydraulic pilot type two-way valve. 5. A control circuit for a water jet processing device according to claim 1, wherein the shutoff valve is an electromagnetic two-way valve. 7. The control circuit for a water jet processing device according to claim 2, wherein the shutoff valve is a hydraulic pilot type two-way valve. 8. A control circuit for a water jet processing device according to claim 2, wherein the shutoff valve is an electromagnetic two-way valve.