JPS642961Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device that generates ultra-high hydraulic pressure and controls the pressure.

(Prior art) When generating ultra-high pressures such as 500 kg/cm ² in a hydraulic circuit, hydraulic shock absorbers (pumps, relief valves, accumulators, check valves, etc.) that can withstand high pressure and high pressure resistance are required. Requires plumbing.

Setting all hydraulic equipment to ultra-high pressure specifications in this way would inevitably result in extremely high costs, and of course, it was usually impossible to use existing hydraulic equipment.

On the other hand, as proposed in Japanese Patent Application Laid-Open No. 49-100664, it is proposed to use two boost cylinders and operate them alternately while synchronizing each other to continuously generate high pressure. There is something I did.

(Problem that the invention aims to solve) However, in this case, since the reference pressure (supply low pressure) of the boost cylinder is always the pump discharge pressure, the pressure control of the generated high pressure cannot be performed accurately, and the high pressure Even if the target value changes,
There was a problem in that pressure control could not be carried out in response to this. Naturally, if this generated high pressure is to be accurately controlled using, for example, a pressure control valve, this control valve must be designed to high pressure specifications as described above.

An object of the present invention is to provide an ultra-high pressure control device that can generate ultra-high pressure without using a high-pressure pump or the like and can control the generated pressure with extremely high precision in accordance with a target setting value.

(Means for solving the problem) The present invention includes a pressure setting device that outputs an electrical pressure setting signal, and an electro-hydraulic servo valve that selectively controls the flow rate from two ports according to the pressure signal. , an amplification valve that proportionally increases this flow rate, two boost cylinders that generate high pressure according to the piston area ratio in response to the hydraulic fluid from the amplification valve, and an electro-hydraulic servo valve that detects the generated high pressure. A pressure detector that provides feedback to the tank, a plurality of pilot check valves that are arranged in parallel in a circuit that releases the generated high pressure to the tank side, and orifices that are arranged in series with these valves, and a plurality of pilot check valves that receive the high pressure. A switching valve and a pressure switch that sequentially supply pilot operating pressure according to the pressure in the relief circuit, and a sequence circuit that alternately causes the boost cylinder to generate high pressure and controls the supply of pilot operating pressure to the pilot check valve. Equipped with. Therefore, the generated high pressure can be arbitrarily and accurately controlled depending on the hydraulic oil from the amplification valve, and the generated pressure can also be safely lowered.

Hereinafter, embodiments of the present invention will be described based on the drawings.

1 is a pressure setting device which inputs an electrical signal (target pressure value) to an adder 2;

3 is an amplifier which supplies a drive signal to the electro-hydraulic servo valve 5 via the changeover switch 4;

The output from the pressure detector 6 of the high pressure generating section, which will be described later, is input to the adder 2 as a feedback signal via the amplifier 7, and the electro-hydraulic servo valve 5 is configured to eliminate the difference between the target setting value and the feedback value. Operate.

This electro-hydraulic servo valve 5 is of a type that can control the port flow rates in two directions, and is equipped with the changeover switch 4 that inverts the input value of the signal (converts the polarity) in order to switch the control ports. It will be done.

8 is an amplification valve that proportionally increases the flow rate from the electro-hydraulic servo valve 5, and supplies hydraulic oil to the first boost cylinder 10 or the second boost cylinder 11.

Since the first and second boost cylinders 10 and 11 have substantially the same structure, only one structure will be described for convenience of explanation.

Inside the cylinder 12, piston parts 13 and 14 having different sizes and pressure receiving areas are slidably housed, and these parts are integrally connected and located in a large-diameter cylinder chamber 15 and a small-diameter cylinder chamber 16, respectively. .

The large-diameter cylinder chamber 15 is supplied with hydraulic oil from the amplification valve 8, and the small-diameter cylinder chamber 16 is connected to high pressure generation circuits 17A and 17B, and supplies ultra-high pressure to the high-pressure actuator 18.

In other words, the boost cylinders 10 and 11 generate a pressure in the cylinder chamber 16 that is increased by increasing the hydraulic pressure supplied to the cylinder chamber 15 according to the area ratio of the piston parts 13 and 14.

These first and second boost cylinders 10, 1
Pressure oil is selectively supplied to the cylinder chamber 15 from the amplifying valve 8 via circuits 20A and 20B, and when pressure oil is sent to one cylinder chamber 15 to generate ultra-high oil pressure, the other cylinder chamber 15 is is released to low pressure and returns to its initial position in preparation for the next operation.

Two such boost cylinders 10, 11
As will be described later, the operation is controlled by switching the operating port of the electro-hydraulic servo valve 5.

The switching valve 22 switches the hydraulic oil for the back pressure chamber 23 of the large diameter piston portion 13 of the boost cylinders 10, 11. When extremely high pressure is generated, the back pressure chamber 23 is switched to low pressure (tank) via circuits 24A and 24B. pressure), and during the initial position return operation, the pressure is switched to high pressure (however, when the piston moves, the cylinder chamber 15 on the opposite side does not require such high pressure because it is tank pressure).

The operation of the boost cylinders 10 and 11 is as follows.
They are detected by limit switches 25A and 25B provided near the stroke ends, respectively, and input to a sequence circuit 26 that manages the overall operation of these switches. The sequence circuit 26 controls the operation of the changeover switch 4 and the changeover valve 22, and also controls the operation of a changeover valve 27 that controls the pressure of the high pressure circuit, which will be described later.

Check valves 28A and 28B are installed in the high pressure generation circuits 17A and 17B, respectively, to prevent high pressure oil from returning to the boost cylinders 10 and 11. Check valves 29A and 29B are respectively provided for allowing hydraulic oil to flow into the cylinder chamber 16 from circuits 24A and 24B when the cylinder is returned to its initial position.

A pressure detector 6 is interposed after the junction of the high pressure generating circuits 17A and 17B to detect the generated pressure and supply it to the adder 2 as a feedback signal.

30A and 30B are switching valves that are in the circuit between the electro-hydraulic servo valve 5 and the amplification valve 8 and release oil returned to the tank side. Pressure oil is supplied from an oil pump in a separate system by bypassing the valve 5, and as a result, the amplification valve 8 is connected to the electro-hydraulic servo valve 5.
A large flow rate proportional to the flow rate of .

First, in the above configuration, when the pressure setting device 1 is operated to set a desired high pressure value, the electrical signal based on this is amplified and sent to the electro-hydraulic servo valve 5 via the changeover switch 4. input.

At this time, assuming that the first boost cylinder 10 is operated by the operation control signal from the sequence circuit 26 and the second boost cylinder 11 is maintained in a standby state, the flow rate control port of the electro-hydraulic servo valve 5 is The selector switch 4 is held so as to send working fluid to the circuit 20A of the amplification valve 8.

Therefore, the pressure oil sent from this amplification valve 8 to the circuit 20A causes the first boost cylinder 10 to start operating rightward in the figure, and the piston portion 1
The pressure in the cylinder chamber 16 is increased in proportion to the area ratio between 3 and 14.

The high voltage thus generated is supplied to the actuator 18 through the circuit 17A.

This generated pressure is fed back via the pressure detector 6 and compared with the target value from the pressure setting device 1.

As a result, as long as the actual generated pressure is lower than the target value, the first boost cylinder 1
0 works. By the way, if this boost cylinder 10 reaches the stroke end before the pressure rises to the set value and further pressurization becomes impossible, the sequence circuit 26 switches the changeover switch 4 when the limit switch 25B detects this. At the same time, the ports of the switching valve 22 are switched.

Then, the control port of the electro-hydraulic servo valve 5 is reversed, and the circuit 20B is connected via the amplification valve 8.
Hydraulic oil begins to be supplied to the tank side, and the other circuit 20A becomes low pressure as the switching valve 30A communicates with the tank side (this is also controlled via the sequence circuit 26).

Therefore, the second boost cylinder 11 starts high pressure generation operation in the same manner as above, and the circuit 1
The check valve 28B is pushed open from 7B to supply high pressure oil to the actuator 18.

On the other hand, at this time, the first boost cylinder 10
, the pump discharge oil is supplied from the switching valve 22 to the back pressure chamber 23 via the circuit 24A, so a differential pressure is generated on both sides of the piston part 13, and the piston part 13 moves to the left in the figure. and 14 are pushed back, and at the same time, the check valve 29A is opened in the cylinder chamber 16, and the hydraulic oil from the circuit 24A flows into the cylinder chamber 16.

Such an initial position return operation is stopped via the sequence circuit 26 when the limit switch 25A detects that the stroke end has been reached, in order to prepare for the next operation.

On the other hand, during this time, the high pressure generated by the action of the second boost cylinder 11 is fed back via the pressure detector 6 in the same way as above, so the operation will continue until the target value is reached. become.

Especially when the capacity of the actuator 18 is large, the first and second boost cylinders 1
0 and 11 repeat this operation alternately to reach the desired high pressure value. As a result of such operation, when the target pressure value is reached, at that point the first or second boost cylinder 10, 11 (whichever was operating immediately before) stops operating and returns to the set pressure. Maintain circuit pressure. When the pressure drops due to a leak in the actuator 18 or the circuit, the pressure detector 6 detects this and immediately provides feedback, so the electro-hydraulic servo valve 5 operates again based on this feedback signal, and the amplification valve 8 Hydraulic oil is sent to the boost cylinder 10 or 11 via the boost cylinder 10 or 11 to increase the pressure in the circuits 17A and 17B to the target value.

In this way, it is possible to supply ultra-high pressure to the actuator 18 with extremely high precision control.
Since ultra-high pressure does not directly act on (or generate) the ultra-high pressure (expressed as PL), there is no need to set these to ultra-high pressure specifications, but simply the discharge side circuit of the first and second boost cylinders 10 and 11. It is only necessary to increase the voltage resistance of only the constituent members, and in particular, the shorter the connection between the boost cylinders 10, 11 and the actuator 18, the fewer the voltage resistance circuits.

Next, a control circuit necessary for lowering the ultra-high voltage generated in this manner will be explained.

In this embodiment, there is a circuit 32 that releases high pressure from the actuator 18 to the tank side.
3 pilot check valves 33, 34, 35, 3
6 are interposed in parallel, and each of these pilot check valves 33 to 36 is supplied with pilot operating pressure from a switching valve 27, and when this pilot pressure is supplied, the check valves 33 to 36 open to lower the pressure. ing.

Of these, pilot check valves 33, 34,
There are variable orifices 38 and 3 downstream of 35, respectively.
9 and 40 are interposed to regulate the relief flow rate.

After the first pilot check valve 33 is opened, the second pilot check valve 34 is opened after the pressure has decreased to a predetermined value, and then the third pilot check valve 35 is opened.
Switching valves 43 and 44 operated via first and second pressure switches 41 and 42, respectively, are interposed in the pilot pressure supply lines of pilot check valves 34 and 35.

Therefore, even if the switching valve 27 is switched to the pressure drop side in response to a signal from the sequence circuit 26, the first pilot check valve 33 opens first.
After that, the second pilot check valve 34 opens only when the pressure drops to a predetermined value and the switching valve 43 is activated via the pressure switch 41.

In this way, sequentially check the pilot check valves 33 to 33.
35 is operated in order to always maintain the rate of pressure drop at a predetermined constant value.If only a single pilot check valve is used, the pressure will drop rapidly when the initial pressure is large due to the characteristics of its orifice. However, as the pressure subsequently decreases, the rate of pressure reduction slows down, and especially when a certain rate regulation is required to reduce the initial ultra-high pressure, the final velocity becomes extremely slow and it takes a considerable amount of time to release the pressure. This is to avoid overspending.

The fourth pilot check valve 36 does not open during normal pressure drop control, and opens only when a signal is sent from the sequence circuit 26 to the switching valve 27 in an emergency when pilot pressure is supplied.

At this time, no orifice for regulating the flow rate is provided downstream of the pilot check valve 36 so that the pressure can be released quickly.

Note that 46 and 47 indicate pressure switches that detect pressure rise and fall and switch over.

Therefore, in the above configuration, when the extremely high pressure generated in the circuit 32 is to be lowered, the switching valve 27 is switched through the sequence circuit 26, and pilot pressure is supplied to the pilot check valves 33-35.

If the pressure in the circuit 32 at that point is higher than the set value of the first pressure switch 41, only the first pilot check valve 33 opens and high pressure oil escapes to the tank via the orifice 38. .

Next, when the circuit pressure drops to the set value of the first pressure switch 41, the switching valve 43 of the second pilot check valve 34 operates, the second pilot check valve 34 also begins to open, and the other orifice opens. High-pressure oil also begins to leak through 39. Therefore, even though the pressure in the circuit 32 has decreased relatively, the rate of decrease in circuit pressure remains the same.
The pressure is lowered smoothly and the third pilot check valve 35 opens when the second pressure switch 42 is activated in the same way.

In this way, the oil pressure in the ultra-high pressure circuit is reduced extremely smoothly within a safe speed range.

On the other hand, if an emergency situation occurs and you want to immediately lower the circuit pressure, you can switch the switching valve 27 via the sequence circuit 26 to supply pilot pressure only to the fourth pilot check valve 36, thereby reducing the orifice pressure. By opening the fourth pilot check valve 36, which allows a large flow rate to flow, the pressure in the circuit 32 can be rapidly reduced.

(Effects of the invention) As explained above, according to the invention, ultra-high pressure can be generated extremely smoothly and the pressure value can be accurately controlled to the target value. It is only necessary to use high-pressure equipment on the downstream side of the pump, and therefore, pumps, electro-hydraulic servo valves, etc. can be replaced with general-purpose existing pressure-resistant equipment, reducing production costs.

In addition, the high pressure that has been generated can be lowered very smoothly within the safe speed range, so the operability is extremely good when repeatedly generating and lowering ultra-high pressure. Become.

In particular, the present invention is configured to lower high oil pressure by sequentially operating multiple pilot check valves, and in this case, the pilot check valve has a simpler structure and is less likely to malfunction than a servo valve. As described above, since it is easy to control, it greatly contributes to realizing high reliability and quick work cycles.

[Brief explanation of drawings]

The figure is a hydraulic circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Pressure setting device, 2... Adder, 4... Changeover switch, 5... Electric-hydraulic servo valve, 6... Pressure detector, 8... Amplification valve, 10, 11... Boost cylinder, 13 , 14... Piston part, 15,
16...Boost cylinder chamber, 17A, 17B...
...High pressure generation circuit, 18... Actuator, 22
...Switching valve, 33-36...Pilot check valve, 38-40...Orifice, 41,42...
Pressure switch, 43, 44... switching valve.

Claims (1)

[Scope of utility model registration request] A pressure setting device that outputs an electrical pressure setting signal, an electro-hydraulic servo valve that selectively controls the flow rate from two ports according to the pressure signal, an amplification valve that proportionally increases this flow rate, and an amplification device. Two boost cylinders generate high pressure according to the piston area ratio in response to the hydraulic fluid from the valve, a pressure detector detects the generated high pressure and feeds it back to the electro-hydraulic servo valve, and the generated high pressure is transferred to the tank side. A plurality of pilot check valves are arranged in parallel in a circuit that releases the high pressure to the high pressure, and orifices are arranged in series with these valves, and the pilot operating pressure is sequentially adjusted to the plurality of pilot check valves according to the pressure of the circuit that releases the high pressure. An ultra-high pressure control device characterized by comprising: a switching valve and a pressure switch for supplying high pressure, and a sequence circuit that alternately causes a boost cylinder to perform high pressure generation operation and controls the supply of pilot operating pressure to a pilot check valve. .