JPS6140961Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a proportional pressure/flow control valve in which both the flow rate control function and the pressure control function are controlled by proportional electromagnetic control.

[Prior Art] Proportional control of both the flow rate control function and the pressure control function is possible by combining known valves. Now, to explain this using the control of an injection cylinder of an injection molding machine as an example, the relationship between the speed of the cylinder and the pressing pressure is generally required to be as shown in FIG. 1.

In other words, during the stroke of the cylinder to the stroke end SE, the flow rate control valve performs cylinder speed control in multiple stages as shown by the solid line, while the pressure control valve controls the load shown by the broken line as shown by the two-dot chain line. Set the cylinder internal pressure higher than the expected maximum load pressure generated by
When the cylinder reaches the stroke end SE, the opening degree of the flow control is kept open to a certain extent, and
As shown by the dotted chain line, the pressure control valve controls the pressing pressure of the cylinder in multiple stages.

When such control is performed using a combination of the conventional pressure compensated proportional flow control valve 51 and proportional relief valve 52 shown in FIG.
Even during the cylinder speed control, the discharge pressure of the hydraulic pump 54 is maintained at a constant pressure slightly higher than the expected maximum load pressure of the cylinder internal pressure, so energy saving is not achieved.

Furthermore, as shown in Fig. 3, there is a system in which a load pressure sensitive flow control valve 55 is used as the flow control valve, but in this case, the discharge pressure of the hydraulic pump 54 during cylinder speed control is always several kg above the load pressure. / ^cm2 , which saves energy, but since this flow control valve does not have a proportional pressure control function, it is necessary to separately provide a proportional relief valve 52, making the structure complicated. Become.

Furthermore, for example, "Hydraulic pressure of machines that answer questions (Part 1)" written by Daikin Industries Hydraulics Technology Group (first edition, 6th edition, published by Gijutsu Hyoronsha Co., Ltd., July 5, 1976).
It is also possible to use a composite valve with proportional electromagnetic control as shown in Figure 3.118 on page 251, but in this case, when the flow rate control spool is returned to neutral, the cylinder port will be connected to the vent unload path. Since the cylinder port is connected, the pressure drop in the cylinder port is carried out without any problem, but if the pilot poppet controls the pressure drop with the flow control switching valve spool holding its variable orifice at the throttle control opening,
Pressure oil in the cylinder port during pressure drop must flow through a restriction in the pilot line, which disadvantageously results in an abnormally long pressure drop time.

[Problem that the invention attempts to solve]

In view of the current situation, the present invention aims to provide a proportional flow control valve that performs proportional control of both the flow rate control function and the pressure control function, and also eliminates the delay in pressure drop time during pressure control. , which aims to eliminate the above-mentioned conventional drawbacks.

[Means for solving problems]

In order to achieve the above-mentioned purpose, the proportional pressure flow control valve of the present invention includes a flow control valve element that controls the throttle opening between the pressure port and the cylinder port, and one surface of which communicates with the pressure port. A piston is disposed in a pressure port chamber and has a spring pressure applied to its other surface, and is slid by the pressure difference before and after the throttle applied to both surfaces of the piston, thereby opening the pressure port chamber to a tank port. a pressure compensating valve element for controlling the opening degree of another throttle that communicates with a drain chamber communicating with the cylinder port, and communicating the piston chamber in which the first spring is disposed with the cylinder port via the fixed throttle; A pilot valve element for controlling the pressure in a piston chamber, wherein the flow control valve element is a proportional electromagnetic flow control valve, the pilot valve element is a proportional electromagnetic pilot pressure control valve, and The present invention is characterized in that a check valve is provided between the cylinder port and the pressure port to allow free flow from the cylinder port to the pressure port and to prevent reverse flow.

[Effect]

In the proportional pressure flow control valve of this invention, both the flow rate and pressure control valve elements are controlled by proportional solenoid valves, so the flow rate control function and pressure control function can be performed individually by proportional solenoid control, and when the pressure drops, the flow rate is controlled. The check valve bypasses the throttle, thus preventing delays in pressure drop time and lengthening of cycle time.

〔Example〕

FIG. 4 is an explanatory diagram of an embodiment of the present invention, partially shown in cross section. In the figure, reference numeral 1 denotes a valve body, which includes a flow rate control throttle valve element A, a pressure compensation valve element B, and a pilot valve element C. 2 is a directional control valve connected to the valve body 1, 3 is an actuation cylinder connected to the directional control valve 2, 4 is a hydraulic pump connected to the valve body 1, and 5 is connected to the valve body 1 and the directional control valve 2. The oil storage tank 4 is a check valve installed in a pipe line 7 connected to the inlet and outlet of the valve body 1.

In the flow rate control throttle valve element A, 11 is a spool having a diameter reducing notch 12 in the center, 13 is a spring interposed in this spool 11,
1 is always pressed to the left. 14 is spool 1
1 is a passage provided in 1, 15 is a spring chamber, 16 is a valve body 1
and a variable aperture formed by the spool 11. Reference numeral 17 denotes a solenoid for controlling the flow rate, and its operating rod 18 is in contact with the end face of the spool 11. When the solenoid 17 is excited by an input signal,
The spool 11 slides to the right in proportion to the magnitude of the input signal against the spring 13, changing the opening area of the variable diaphragm 16, and when the input signal turns OFF, the spool 11 is returned to its original position by the spring 13. Return.
D is a cylinder port that communicates with a pressure port chamber 25 (described later) via a variable throttle 16, and this cylinder port D is connected to an operating cylinder 3 via a directional control valve 2.

In the pressure compensating valve element B, a pressure compensating valve 21 is provided with a piston 22 approximately in the center thereof, and a drain passage 23 is provided in the center thereof, and is pushed to the right by a spring 24. 25 is a pressure port chamber, which communicates with the pressure port P of the valve body 1. 26 is a piston chamber, 27 is a fixed throttle, 28 is a drain chamber, 29 is a variable throttle formed by the valve body 1 and the pressure compensation valve 21, and _T1 is a tank port.

In the pilot valve element C, 31 is a pilot valve, 32 is its poppet, 33 is a spring retainer, and 3 is a pilot valve.
4 is a spring interposed between the poppet 32 and the spring retainer 33, and 35 is a spring chamber. 37 is a pressure control solenoid whose operating rod 38 is in contact with the spring retainer 33;
generates a pressure proportional to the magnitude of the input signal applied to the Note that the spring chamber 35 is connected to the pressure compensation valve 21.
A seat 39 opposite the poppet 32 communicates with the piston chamber 26 through a vent port 36.

The pressure port P of the valve body 1 is supplied with a constant discharge amount _Q1 of pressure oil from the hydraulic pump 4, and is also connected to the oil storage tank 5.
are tank port T ₁ of drain chamber 28, spring chamber 1
It communicates with the tank port T ₂ of No. 5 and the directional control valve 2.

In the control valve of the present invention configured as described above,
First, the flow rate control function will be explained. When the directional control valve 2 is switched and the cylinder port D of the valve body 1 and the head side pressurizing chamber of the operating cylinder 3 are in communication, the solenoid 17 is excited in proportion to the input signal and the operating rod 18 is activated. The spool 11 slides in proportion to the input signal of the solenoid 17, stops at a position balanced with the force of the spring 13, and stops at the variable aperture 16.
The opening degree is adjusted to control the flow rate of pressure oil from the pressure port P to the cylinder port D. On the other hand, the hydraulic pressure P ₁ of the pressure port P is applied to the end surface of the piston 22 of the pressure compensation valve 21 on the pressure port chamber 25 side, and the force F of the spring 24 is applied to the end surface of the piston 22 on the piston chamber 26 side. and the hydraulic pressure P ₂ of the cylinder port D through the fixed throttle 27 are applied. Therefore, if both end surfaces S of the piston 22 are formed equally, the relationship P ₁ −P ₂ =F/S is established, and the aperture 16
The pressure compensating valve 21 is set so that the differential pressure before and after the
to adjust the opening degree of the variable diaphragm 29. At this time, the pressure difference before and after the variable throttle 16 is constant regardless of the pressure at the cylinder port D, so a flow rate proportional to the opening degree of the throttle valve 16 flows into the working cylinder 3, and the excess oil sent from the hydraulic pump 4 is From pressure port chamber 25 to variable throttle 29, tank port T ₁
and is sent to the oil storage tank 5.

Note that the fixed throttle 27 provided between the cylinder port D and the piston chamber 26 is connected to the pressure compensating valve 21.
Needless to say, it has a damping effect on the movement of.

Next, the pressure compensation function of the present invention will be explained.
Now, while the directional control valve 2 remains switched, the cylinder 3
When the head side of the cylinder port D and the cylinder port D are in a normal state, when the movement of the piston of the working cylinder 3 is restricted by an external force or the like, the pressures at the pressure port and the cylinder port become equal and rise. When both pressures exceed the set pressure of the pilot valve 31, the poppet 32 opens and the pilot flow flows from the piston chamber 26 through the spring chamber 35 and the drain passage 23 to the drain chamber 28, creating a pressure difference before and after the fixed throttle 27. . As a result, the piston 22 of the pressure compensation valve 21
A pressure difference is generated between both end faces of the hydraulic pump 4, the piston 22 is slid to the left by the pressure oil from the hydraulic pump 4, and the opening degree of the variable throttle 29 is increased to divert most of the hydraulic pressure from the hydraulic pump 4 to the drain chamber 28. from there to the oil storage tank 5. Note that the set pressure of the pilot valve 31 is
Determined by the position of the actuating rod 38 of the solenoid 37 applied to the spring retainer 33, the actuating rod 28
Since the position of is proportional to the input signal applied to the solenoid 37, complex pressure control is possible.

Next, regarding the check valve 6, when the pressure is lowered by the pilot valve element C, as the pressure in the pressure port chamber 25 decreases to the target value, the pressure in the pressure port P decreases to the target value. If not, the pressure oil in the cylinder port D will be sent to the oil storage tank 5 through the variable throttle 16, the variable throttle 29, and the tank port _T1 , and the other to the fixed throttle 27, the piston chamber 26, and the vent port. 3
6. The oil is sent to the oil storage tank 5 through the seat 39, the spring chamber 35, and the drain passage 23. In this case, if the areas of the variable orifices 16 and 29 are small, all the pressure oil has to pass through the small orifices, which takes a long time to drop the pressure, making it impossible to obtain the optimal waveform required for control, and also reducing the cycle time. is also longer. Particularly when the volume on the head side of the cylinder 3 is large, the amount of compression based on the compressibility of oil at high pressure becomes so large that it cannot be ignored. Since the amount of pressurized oil that must be sent from D to tank port T also increases, the aforementioned delay in pressure drop time becomes even more noticeable.

Also, the input signals to the solenoid 17 for flow rate control and the solenoid 37 for pressure control are turned off at the same time.
Then, the spool 11 quickly slides in the direction of closing the variable throttle 16 by the spring 13, so in the absence of the check valve 6, most of the pressure oil in the cylinder port D passes through the fixed throttle 27 and the pilot valve 3
1. The oil is sent to the oil storage tank 5 via tank port _T1 . For this reason, the pressure drop time becomes longer, and an optimum pressure waveform cannot be obtained, and the cycle time becomes further longer.

In the present invention, as shown in FIG. 4, the cylinder port D and the pressure port P are connected through a pipe line 7,
Since a check valve 6 is provided in this pipe line 7 to allow oil to pass only in one direction, the pressure oil in the operating cylinder 3 is
Regardless of the size of the opening area of the variable throttle 16, the oil passes through the check valve 6 to the pressure port P, and is sent to the oil storage tank 5 via the variable throttle 29, thereby preventing delays in pressure drop time and lengthening of cycle time. Can be done.

[Effect of idea]

As is clear from the above explanation, when the pressure flow control valve according to the present invention is applied to, for example, cylinder control of an injection molding machine, the flow control valve is a pressure sensitive flow control valve with a proportional pressure control function. , there is no need for a relief valve, so the pressure oil circuit is simplified and the device can be made smaller. Therefore, it is possible not only to reduce the price but also to save energy. Furthermore, by providing a check valve, it is possible to eliminate delays in pressure drop time and prolongation of cycle time, which has great practical effects.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between cylinder speed and pressing pressure in cylinder control of an injection molding machine.
3 and 3 are respectively pressure oil circuit diagrams in which flow rate and pressure control functions are proportionally controlled by a combination of conventionally known valves, and FIG. 4 is an explanatory diagram of an embodiment of the present invention. A: Throttle valve element for flow rate control, B: Pressure compensation valve element, C: Pilot element, 1: Valve body, 2: Directional control valve, 3: Operating cylinder, 4: Pressure oil pump,
5: Oil storage tank, 6: Check valve, 8: Variable throttle, 11: Spool, 16: Variable throttle, 17: Flow rate control solenoid, 21: Pressure compensation valve, 22:
Piston, 23: Drain passage, 25: Pressure port chamber, 26: Piston chamber, 27: Fixed throttle, 28:
Drain chamber, 29: variable throttle, 31: pilot valve, 37: pressure control solenoid, D: cylinder port, P: pressure port.

Claims (1)

[Claims for Utility Model Registration] A flow control valve element for controlling the throttle opening between a pressure port and a cylinder port; another restriction having a piston to which a pressure is applied, which slides due to the difference in pressure across the restriction applied to both sides of the piston and communicates the pressure port chamber with a drain chamber communicating with the tank port; A pressure compensating valve element that includes a pressure compensating valve that controls the opening degree and communicates the piston chamber in which the first spring is disposed with the cylinder port via a fixed throttle, and a pilot valve element that controls the pressure of the piston chamber. A proportional electromagnetic flow control valve is provided as the flow rate control valve element, a proportional electromagnetic pilot pressure control valve is provided as the pilot valve element, and a cylinder is provided between the cylinder port and the pressure port. A proportional pressure flow control valve characterized by being equipped with a check valve that allows free flow from a port to a pressure port and prevents reverse flow.