JPH04366001A - Hydraulic driven high pressure fluid generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a high-pressure fluid generating device suitable for use in high-pressure working equipment such as cutting systems that perform machining using high-pressure water, and particularly relates to a high-pressure fluid generating device that is suitable for use in high-pressure working equipment such as cutting systems that perform machining using high-pressure water. This invention relates to a hydraulically driven high pressure fluid generator using a pressure vessel.

0002

[Prior Art] A conventional hydraulically driven high pressure fluid generator is
As shown in FIG. 6, a hydraulic power source 1C, a directional switching valve 4C with 4 ports and 2 positions, and a stepped piston type reciprocating pressure intensifier 101
C, an accumulator 30, and a nozzle 13C. In this configuration, when the directional control valve 4C is at the A position in the figure, high pressure oil from the hydraulic source 1C enters the pressure receiving chamber 7C in the large diameter portion on the left side of the pressure intensifier 101C and pushes the piston 5C to the right. The pressure of the fluid, for example water, in the pressurizing chamber 10C in the small diameter portion on the right side of the piston 5C is increased according to its area ratio and is supplied to the nozzle 13C via the check valve 12C. During this time, the oil in the pressure receiving chamber 8C in the right large diameter section returns to the tank 2C, and the pressure inside the pressure increasing chamber 9C in the left small diameter section becomes low, and water is sucked in from the tank 14C or water is supplied by means not shown. When the piston reaches the right stroke end, the directional control valve 4C is switched to a position opposite to that shown in the figure, and the same operation as described above is performed with the left and right sides reversed. By continuously repeating these operations, high pressure fluid is continuously ejected from the nozzle 13C.

0003

FIG. 7(a) shows the change over time in the piston speed of the apparatus shown in FIG. 6, and FIG. 7(b) shows the change over time in the discharge pressure. As shown in FIG. 7(a), the piston 5C
When the piston 5C reaches the right stroke end, the directional control valve 4C switches, so the piston 5C stops for a while and immediately starts moving to the left. The pressure at the nozzle 13C is equal to the pressure at the piston 5
Since the pressure decreases momentarily between the time when C stops and the time when it starts moving to the left, pressure fluctuations as shown in FIG. 6(b) occur. As a result, the following problems arise.

(1) Pressure fluctuations will impede micro-machining and cutting ability when this device is used in a cutting system using high-pressure water, making stable machining impossible.

(2) In the case of (1) above, if the accumulator 30 is used in the high-pressure water circuit to prevent pressure fluctuations, a large-capacity accumulator is required because water has low compressibility. Since this is a high pressure application,
Its flesh is thick, making it extremely large and heavy.

(3) To reduce the occurrence of pressure fluctuations,
It is necessary to shorten the stopping time of piston 5C as much as possible,
In this case, it is necessary to operate the directional control valve 4C at high speed. Therefore, the durability of the directional control valve 4C becomes a problem.
In addition, vibration and noise inevitably increase.

(4) The piston 5C itself must change its direction of motion rapidly, which also becomes a source of noise and vibration.

[0008] There is also a system that is equipped with two pressure intensifiers 101C described above and drives one pressure intensifier while the other is being inspected or repaired. arise.

In view of the above-mentioned problems, it is an object of the present invention to eliminate pressure fluctuations in high-pressure fluid generated in a hydraulically driven two stepped piston type reciprocating pressure intensifier, and to eliminate vibrations of the device.
An object of the present invention is to provide a high-pressure fluid generating device that prevents noise generation and extends the life of a directional control valve and a piston.

0010

[Means for Solving the Problems] In order to achieve the above object, a hydraulically driven high pressure fluid generating device according to the present invention receives pressure oil from one constant flow hydraulic source and generates high pressure fluid discharged from each. two stepped piston type reciprocating pressure intensifiers that are combined to generate high pressure, and a directional control valve that is installed between the two pressure intensifiers and the hydraulic pressure source and can be switched independently, two directional switching valves that are controlled so that the piston has an acceleration section, a constant speed section, a deceleration section, and a stop section, and the two directional switching valves,
The pressure intensifier is controlled by reversing the phase so that when one pressure intensifier is in an acceleration section, the other is in a deceleration section, and when one is in a constant speed section, the other is in a stop section.

[0011]

[Operation] In the present invention constructed as described above, the two directional switching valves are arranged such that when one pressure intensifier is in the acceleration section, the other is in the deceleration section, and when one is in the constant speed section, the other is in the deceleration section. As shown in the stop section, the high pressure fluid discharged from each pressure intensifier is discharged from each pressure intensifier by reversing the phase as shown in the stop section, and the resulting high pressure fluid has a constant flow rate. By continuously repeating the series of operations, High-pressure fluid without pressure fluctuations can be stably obtained.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 5, a case will be described below in which a hydraulically driven high-pressure fluid generator according to an embodiment of the present invention is applied to a cutting system that performs fine machining using high-pressure water.

FIG. 2 shows a schematic diagram of a cutting system using a hydraulically driven high pressure fluid generator according to this embodiment. The cutting system includes a hydraulically driven high pressure fluid generator 100, an on-off valve 15, and a cutting nozzle 40 in a pipe line 1.
It is configured by connecting 6. High pressure fluid generator 100
The pressurized water is sent through the pipe 16 to the cutting nozzle 40 at its tip, and the workpiece is processed by the high-pressure water jetted from the cutting nozzle 40. The spouting and stopping of high-pressure water is controlled by an on-off valve 15.

FIG. 1 shows a hydraulically driven high pressure fluid generator 10.
0 circuit diagram is shown. In FIG. 1, a high pressure fluid generator 1
00 is a hydraulic power source 1, an oil tank 2, two 4-port 3-position directional switching valves 3, 4, two stepped piston type reciprocating pressure intensifiers 101A, 101B, a nozzle 13, a water tank 14, a limit switch 21 , 22, 23, 24, a controller 20, a start switch 25, and the like. Pressure booster 10
1A and 101B are the pistons 5 and 6 and the large diameter pressure receiving chambers 7A, 7B, 8A, and 8B attached thereto, respectively.
, and small diameter pressurization chambers (cylinders) 9A, 9B, 10A
, 10B, and check valves 11 and 12 provided in each of the supply lines of the pressurizing chambers 9A to 10B. The limit switches 21 to 24 are for detecting a certain position from the right stroke end and the left stroke end of the pistons 5 and 6, respectively.
1 and 23 are located a predetermined distance L to the right from the left stroke ends of the pistons 5 and 6, respectively, and limit switches 22 and 24 are located a predetermined distance L to the left from the right stroke ends of the pistons 5 and 6, respectively. It is installed in That is, during the operation of the piston, the position detection member 5A or 6A is set to turn on each limit switch at a certain position before each stroke end. The controller 20 also includes limit switches 21 and 2.
Input signals i1, i2, i3, i4 from 2, 23, 24
Accordingly, the drive signals S1,
Output S2, S3, and S4, respectively. Directional switching valve 3,
4 is an electromagnetic drive system, in which drive signals S1 to S4 are input from the controller 20 to the electromagnetic drive unit and controlled. The check valves 11 and 12 prevent water from flowing back into the pressure receiving chambers 9A to 10B. Further, the directional control valves 3 and 4 are respectively moved from the neutral position N or n to the left and right switching positions A, B or a, b.
The switching time is T1, and the switching position A, B or a, b
If the time to return to the neutral position N or n is T2, then
The relationship between the strength of each spring and the magnetic force of the solenoid is set so that T2>T1.

Next, the above-mentioned hydraulically driven high pressure fluid generator 1
The operation of 00 will be explained with reference to FIGS. FIG. 3 shows the positions of the directional valves 3, 4 and the operating states of the pistons 5, 6 corresponding to the positions of the respective directional valves. In addition, in FIGS. 4 and 5, the horizontal axis represents time, and in FIG. 4(a), the vertical axis represents signals i1, i from the limit switches 21, 22, 23, and
Drive signals S1, S2, S3, corresponding to 2, i3, i4,
FIG. 4(b) shows the relationship between S4 and the stroke of the directional control valves 3, 4, and FIG. 5(a) shows the speed of the pistons 5, 6 on the vertical axis.
As in Fig. 4(b), the vertical axis represents the speed of the pistons 5 and 6,
In FIG. 5(b), the discharge pressure of the pistons 5 and 6 and the sum of both are plotted on the vertical axis, and represent the respective changes. In addition, each state of 0, 1, 2, 3, ... in FIG.
Corresponds to...

First, when the start switch 25 is operated and a start signal is input, initial settings are performed, and then steady operation begins. The details are as follows.

(Initial Setting) When the start signal from the start switch 25 is input, the controller 20 outputs drive signals S2 and S4 to move the directional control valves 3 and 4 to positions B and B on the right side in the figure, respectively. Let piston 5,
6 to the left stroke end (initial position). When the pistons 5 and 6 are initialized, the drive signals S2 and S4 are turned OFF based on the signals i1 from the limit switch 21 and signals from 23 to i3, and the directional control valves 3 and 4 are set to the neutral N and n positions, respectively. return to position.

(State 0: Time t0 to t1) When a predetermined time has elapsed after the drive signals S2 and S4 are turned OFF (this time is defined as t0), the drive signal S1 is turned ON and the directional control valve 3 is in the N position. The piston 5 moves toward the A position, the pressure in the pressure receiving chamber 7A increases, and the piston 5 is accelerated rightward. Therefore,
The discharge pressure of water in the pressure receiving chamber 9B increases and high pressure water begins to be supplied to the nozzle 13. The time it takes for the directional control valve 3 to reach the A position from the N position is T1, as described above, and there is a relationship of T1=t1-t0. On the other hand, since the directional control valve 4 remains at the n position, no oil is supplied from the hydraulic source, and the piston 6 is stopped without moving at the left stroke end position.

(State 1: Time t1-t2) Time t1
Then, the directional control valve 3 reaches the A position, the pressure receiving chamber 7A is increased to a constant pressure by oil supplied from the hydraulic source, and the piston 5 moves to the right at a constant speed. On the other hand, since the drive signals S3 and S4 are in the OFF state, the directional control valve 4 is still in the n position, no oil is supplied from the hydraulic source, and the piston 6 is stopped without moving at the left stroke end position. As a result, the nozzle 13 is supplied with high-pressure water at a constant flow rate and pressure.

(State 2: Time t2-t3) Time t2
Then, the limit switch 22 detects the position L of the piston 5 just before the right stroke end by the position detection member 5A attached to the piston 5, and this signal i2 is taken into the operating circuit of the controller 20. At the same time, according to the logic of the controller 20, the drive signal S1 is turned off as shown in FIG. The rightward speed of the piston 5 is reduced. On the other hand, S3 is turned on, the directional switching valve 4 is turned from the n position to the a position, the pressure in the pressure receiving chamber 8A increases, and the piston 6 is accelerated rightward.

Here, the time for the directional control valve 3 to reach the N position from the A position is T2 seconds as described above, and the time for the directional control valve 4 to reach the N position from the N position is T2 seconds as described above. is T1 (<T2) seconds. Therefore, the directional control valve 4 is fully opened before the directional control valve 3 is fully opened, and the remaining pressure oil supplied to the directional control valve 3 is supplied to the directional control valve 4, and the amount of oil supplied from the hydraulic source 1 is Since is constant, the piston 6 is accelerated during time T2 with the phase reversed in response to the deceleration of the piston 5. Therefore, piston 5
An amount of high-pressure water equal to the amount decreased from is discharged from the piston 6, and the total flow rate of high-pressure water reaching the nozzle 13 is (state 1)
The pressure is also the same as in the case of . Furthermore, T2=t
There is a relationship of 3-t2.

(State 3: Time t3 to t4) Time t3
Then, the directional control valve 3 reaches the N position, no oil is supplied from the hydraulic source to the piston 5, and the piston 5 reaches the right stroke end and stops. On the other hand, the directional control valve 4 has reached the a position, oil is supplied from the hydraulic source, the pressure receiving chamber 8A is increased to a constant pressure, and the piston 6 moves to the right at a constant speed. Therefore, the flow rate and pressure of high-pressure water supplied from the nozzle 13 are equal to those in (state 1).

(State 4: Time t4-t5) Time t4
Then, the limit switch 24 detects the position L before the right stroke end by the position detection member 6A attached to the piston 6, and this signal i4 is sent to the controller 2.
0's operating circuit. At the same time, the drive signal S3 is turned OFF, the directional control valve 4 is directed from the a position to the n position by the force of the spring, the pressure in the pressure receiving chamber 8A is reduced, and the rightward speed of the piston 6 is reduced. On the other hand, S2 is turned ON, and the directional control valve 3 is directed from the N position to the B position.
The pressure in the pressure receiving chamber 7B increases and the piston 5 is accelerated leftward. At this time, the rightward speed of the piston 6 is decelerated, thereby reducing the water discharge pressure in the pressure receiving chamber 10B, but at the same time, the piston 5 reverses its phase and moves leftward, as in the case of state 2 (t2 to t3). , the discharge pressure of the water in the pressure receiving chamber 9A increases, and since the amount of oil supplied from the hydraulic source 1 is constant, the same amount of high-pressure water as decreased from the piston 5 is discharged from the piston 6, Therefore, the flow rate and pressure of high-pressure water reaching the nozzle 13 are equal to those in (state 1).

(State 5: Time t5 to t6) Time t5
Then, the directional control valve 4 reaches the n position, no oil is supplied from the hydraulic source, and the piston 6 reaches the right stroke end and stops. On the other hand, the directional control valve 3 has reached the B position,
Oil is supplied from the hydraulic source, pressure is increased to a constant pressure in the pressure receiving chamber 7B, and the piston 5 moves to the left at a constant speed. Therefore, the flow rate and pressure of high-pressure water supplied from the nozzle 13 are (
This is equivalent to state 1).

(State 6: Time t6-t7) Time t6
Now, limit switch 2 is detected by position detection member 5A.
1 detects the position L before the left stroke end of the piston 5, and this signal i1 is taken into the operating circuit of the controller 20. At the same time, drive signal S2 is turned off.
, and the directional control valve 3 moves from the B position to the N position by the force of the spring.
position, the pressure in the pressure receiving chamber 7B decreases, and the piston 5
The leftward velocity of is reduced. Meanwhile, S4 is turned on,
The directional control valve 4 faces from the n position to the b position, the pressure in the pressure receiving chamber 8B increases, and the piston 6 is accelerated leftward. At this time, for the same reason as in (state 2), nozzle 13
The flow rate and pressure of the high-pressure water that reach this point are the same as in (state 1).

(State 7: Time t7-t8) Time t7
Then, the directional control valve 3 reaches the N position, no oil is supplied from the hydraulic source, and the piston 5 reaches the left stroke end and stops. On the other hand, the directional control valve 4 has reached the b position, oil is supplied from the hydraulic source, the pressure receiving chamber 8B is pressurized with a constant pressure, and the piston 6 moves to the left at a constant speed. Therefore, the flow rate and pressure of high-pressure water supplied from the nozzle 13 are equal to those in (state 1).

(State 8: Time t8-t9) Time t8
Then, the limit switch 23 detects the position L before the left stroke end by the position detection member 6A,
This signal i3 is taken into the operating circuit of the controller 20. At the same time, according to the logic, the drive signal S4
is turned off, the directional control valve 4 is directed from the b position to the n position by the force of the spring, the pressure in the pressure receiving chamber 8B is reduced, and the leftward speed of the piston 6 is reduced. On the other hand, S1 is ON
, the directional control valve 3 moves from the N position to the A position, the pressure in the pressure receiving chamber 7A increases, and the piston 5 is accelerated rightward. At this time, for the same reason as in (state 4), the flow rate and pressure of the high-pressure water reaching the nozzle 13 are equal to those in (state 1).

After time t9, this hydraulically driven high pressure fluid generator is operated by repeating the steady operation from time t1 (state 1) to time t8 (state 8) as one cycle. From the above (state 1) to (state 8)
) The pressure and flow rate of the high-pressure water supplied from the nozzle 13 are constant in any state. Then, by continuously repeating the same cycle after this, high-pressure water can be continuously obtained.

The relationship between the flow rate and pressure of the high-pressure fluid from the nozzle 13 in the case of the above embodiment will now be examined.

The flow rate from the nozzle 13 is

[0031]

[Math 1]

(Q: flow rate from the nozzle, k: constant, A:
It is determined by the nozzle passage area, P: high pressure fluid pressure),
If the pressure increase ratio of the pressure intensifiers 101A and 101B is m, the oil flow rate is

[0033]

[Equation 2] Qoil = m・Q ... (2) The pressure is

[0034]

[Equation 3] Poil = 1/m·P (3). Therefore, if the hydraulic pressure source supplies a constant flow rate, the pressure of the high-pressure fluid will theoretically remain unchanged (however, A is fixed). The same applies even if the hydraulic pressure source supplies a constant pressure. In reality, some fluctuations are unavoidable due to changes in the line resistance of pressure boosters, directional control valves, etc., but these changes do not result in a sudden drop from a predetermined discharge pressure to around 0 as in the conventional technology. There is no change in the discharge pressure (undulation), and the width of the change is small and can be considered to be within the permissible range.

In the above embodiments, the directional control valve was operated electrically by detecting the position a certain distance from the stroke end of the pressure intensifier. A method using hydraulic pressure or the like, a method using a timer depending on operating conditions, a method using direct mechanical connection (link, etc.), etc. may be used.

As described above, according to this embodiment, by reversing the phases of the operations of the two directional control valves and the pistons controlled by them, high-pressure water with a substantially constant pressure can be obtained, and the operation By continuously repeating the cycle, high-pressure water without pressure fluctuations can be stably obtained. Therefore,
With cutting systems that use high-pressure water, it is possible to perform fine processing with low noise.

[0037]

[Effects of the Invention] According to the present invention, the two directional control valves are
Since the phase is reversed for control, the following effects can be expected.

(1) The high-pressure fluid obtained by the pressure intensifier of this system basically has no pressure fluctuations, and when applied to a cutting system or the like, it becomes possible to perform fine processing.

(2) Since the resulting high-pressure fluid has no pressure fluctuations, a large and heavy high-pressure accumulator is not required, making it possible to reduce the size, weight, and cost.

(3) The directional control valve may be switched slowly, and it is also possible to provide a certain stopping time. Therefore, there is no generation of vibration or noise, and there are no problems such as spool fatigue or seal seizure, and a long life can be expected.

(4) There is no need to drive the piston of the amplifier by changing its direction suddenly, eliminating fatigue, vibration, and noise caused by impact.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a hydraulically driven high pressure fluid generating device according to the present invention.

FIG. 2 is a schematic diagram of a cutting system according to an embodiment of the invention.

3 is a diagram showing the operating states of the directional control valves 3 and 4 and the pistons 5 and 6 in the hydraulically driven high pressure fluid generator shown in FIG. 1. FIG.

FIG. 4 is a time chart showing the operation of the hydraulically driven high-pressure fluid generator shown in FIG.
, i4, and the relationship between the operating characteristics of the drive signals S1, S2, S3, S4 and the strokes of the directional valves 3, 4, (b) is a diagram showing the temporal change in the speed of the pistons 5, 6. It is.

FIG. 5 is a time chart showing the operation of the hydraulically driven high pressure fluid generator shown in FIG.
(b) is a diagram showing time changes in the velocity of the pistons 5 and 6, and FIG.

FIG. 6 is a diagram showing a hydraulically driven high pressure fluid generating device according to the prior art.

FIG. 7 is a time chart showing the operation of a hydraulically driven high-pressure fluid generator according to the prior art, in which (a) is a diagram showing changes in piston speed, and (b) is a diagram showing changes in piston discharge pressure.

[Explanation of symbols]

1 Hydraulic sources 3, 4 Directional switching valves 5, 6 Pistons 5A, 6A Position detection members 7A, 7B attached to pistons 5 and 6 Pressure receiving chambers 8A, 8B of piston 5 Pressure receiving chambers 9A, 9B of piston 6 Pressure increase chamber 10A, 10B Pressure increase chamber 13 of piston 6 Nozzle 20 Controller 21, 22, 23, 24 Limit switch i1, i
2, i3, i4 Piston position detection signal S1, S2,
S3, S4 Directional switching valve drive signal 100 High pressure fluid generator 101A, 101B Pressure booster

Claims (1)

[Claims] 1. Two stepped piston type reciprocating pressure intensifiers that receive pressure oil from one constant flow hydraulic source and generate high pressure by merging high pressure fluids discharged from each;
A directional control valve that is installed between the two pressure intensifiers and the hydraulic power source and can be switched independently, such that the piston of each amplifier has an acceleration section, a constant speed section, a deceleration section, and a stop section. The two directional switching valves to be controlled and the two directional switching valves are arranged such that when one pressure intensifier is in the acceleration section, the other is in the deceleration section, and when one is in the constant speed section, the other is stopped. 1. A hydraulically driven high-pressure fluid generating device, comprising: means for controlling the phase by reversing the phase as shown in the section.