JPH0353294Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an electrostrictive proportional servo control valve for controlling the flow rate or pressure of fluid such as fuel gas.

[Conventional technology]

An example of a conventional proportional operation type servo valve is a gas proportional control valve. This is configured to proportionally control the valve opening of the main valve by controlling the pressure in the main diaphragm chamber with a servo regulator, but an electromagnetic plunger is used as the drive source for the servo regulator. It is being

[Problem that the invention attempts to solve]

However, since the electromagnetic plunger has a structure in which the plunger is attracted by a solenoid coil, the structure and assembly work are not only complicated, but also the electromagnetic plunger is prone to failure. In particular, since the electromagnetic plunger used in the servo regulator requires delicate adjustment of its operating amount, it has been necessary to ensure sufficient machining accuracy and assembly accuracy. Therefore, there is a drawback that the cost is generally high.

This invention was made by focusing on such conventional problems, and by using an electrostrictive actuator instead of an electromagnetic solenoid, it is an electrostrictive proportional operation type servo control that can simplify the configuration and reduce costs. The purpose is to obtain a valve.

[Means for solving problems]

In the electrostrictive proportional servo control valve according to this invention, the valve body has an inlet and an outlet communicating through a main port, and the main valve, which is always biased in the closing direction by a spring, is connected to the main port. A servo diaphragm is provided to respond to the fluid pressure on the outlet side of the main valve, and the operation of the servo diaphragm supports the main valve. The working pressure of the main diaphragm corresponding to the fluid pressure on the outlet side is adjusted by a servo valve, and the servo diaphragm is directly displaced by a piezoelectric actuator.

[Effect]

The piezoelectric actuator in this invention obtains an electrical-mechanical output by applying voltage to a layered piezoelectric element consisting of several dozen or more piezoelectric elements, or a bimorph type consisting of two piezoelectric elements stacked together.The piezoelectric actuator's mechanical output is By directly controlling the displacement of the servo diaphragm, the valve opening of the main valve is proportionally controlled in accordance with the controlled displacement, simplifying and downsizing the configuration as a servo diaphragm actuator. It is also possible to reduce costs.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings. In FIG. 1, 1 is a valve body having an inlet 3 for fluid such as gas and an outlet 4 for fluid, which are communicated through a main port 2, and 5 is a valve body that controls the fluid pressure on the outlet side by opening and closing the main port 2. Main valve, 6 is a guide rod that guides the main valve 5 in the opening/closing direction, 7 is the main valve 5
A return spring 8 is provided on the outlet side of the main valve 5 to support the main valve, and a return spring 8 always biases the main valve in the closing direction. are doing.

10 is the servo regulator, this is case 1
1, a servo valve member 13 attached to the servo diaphragm 12, and a pilot passage 14 opened and closed by the servo valve member 13. A pressure chamber 15 below the servo diaphragm 12 communicates with the outlet 4 through a passage 16. Further, the pilot passage 14 is branched into passages 18 and 19 via a passage 17, and the passage 18 communicates with the working pressure chamber 9.
The passage 19 communicates with the inlet 3 via a flow restricting orifice 20.

A restraining member 22 is installed on the servo diaphragm 12 via a return spring 21,
A piezoelectric actuator 23 is mounted on this restraining member 22.
one end is touching. Further, a power supply circuit 24 is connected to the piezoelectric actuator 23 for electrostrictive operation of the piezoelectric actuator 23.

By the way, the piezoelectric actuator 23 is an element that causes displacement due to strain when voltage is applied.
Acts as an electro-mechanical converter, and is broadly classified into laminated piezoelectric actuators and bimorph piezoelectric actuators.

(a) Laminated piezoelectric actuator Since the amount of displacement is small with one piezoelectric element, the second
As shown in the figure, by stacking several tens or more piezoelectric elements P, it is constructed so that a large amount of mechanical displacement can be extracted in series. Here, the ↑ mark indicates the polarization direction, and the input voltage is connected to each element P in parallel. By applying a DC voltage E to this laminated actuator, stable displacement can be obtained. It is characterized by its ability to produce relatively large amounts of force.

(b) Bimorph type piezoelectric actuator The bimorph type piezoelectric actuator is constructed by pasting together two thin plates of piezoelectric elements P. Based on this wiring method, there are a series type shown in FIGS. 3a and 3b and a parallel type shown in FIGS. 4a and 4b. When a DC voltage E is applied to this bimorph type piezoelectric actuator, one element expands and the other element contracts, causing it to bend, and the displacement is extracted by the method shown in FIGS. 5a and 5b and used as an actuator.
The characteristic of this bimorph type is that although it cannot generate large forces, it can take large displacements.

In FIG. 4, q is a metal elastic plate serving as an electrode interposed at one end between the piezoelectric elements p, and r is a metal foil connecting the other ends of the piezoelectric elements p.

Next, the operation will be explained with reference to FIG.

First, in order to proportionally control the gas pressure according to the voltage level, a predetermined DC voltage is applied to the piezoelectric actuator 23 from the power supply circuit 24. Therefore, due to the electrostrictive action of the piezoelectric actuator, the vicinity of its tip is displaced, and the servo diaphragm 12 is held down by the member 2.
2. Push down via return spring 21,
Along with this, the servo valve member 13 also descends, narrowing the pilot passage 14. Therefore, the internal pressure of the working pressure chamber 9 communicating with the inlet 3 and the passage 19 rises to the pressure _P1 , and the main diaphragm 8, which has a large pressure receiving area for the internal pressure, rises against the return spring 7. Push up the valve to open main port 2. As a result, fluid flows out from the inlet 3 to the outlet 4, and the pressure P ₂ inside this outlet 4 increases. When this pressure P ₂ reaches the set value or more,
This acts on the pressure chamber 15 through the passage 16, and the servo diaphragm 12 is pushed upward.
Therefore, the servo valve member 13 is connected to the pilot passage 1.
4 to lower the pressure in the working pressure chamber 9. Therefore, the main valve 5 is lowered together with the main diaphragm 8, operating in the direction of closing the main port 2, and the pressure at the outlet 4 is maintained at a predetermined value. In other words, the fluid pressure at the outlet 4 can be proportionally controlled in accordance with the displacement control of the servo diaphragm by the piezoelectric actuator 23.

FIG. 6 shows another embodiment of this invention. This is different from what is shown in Fig. 1 in that the main valve 5A is integrated into the main diaphragm 8A itself, and the main diaphragm 8A is attached in the direction (upward) that closes the main port 2A by means of a return spring 7A. In addition to the return spring 2
1A, the servo valve member 13A is biased to always close the pilot passage 14A.
Note that other components that are the same as those shown in FIG. 1 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

In this embodiment, when a DC voltage is first applied to the piezoelectric actuator 23 from the power supply circuit 24, the tip of the piezoelectric actuator 23 is displaced by an amount corresponding to this voltage level, and the servo diaphragm 12 is therefore pushed downward. . Therefore, the servo valve member 13A is connected to the pilot passage 1.
4A is opened, and the internal pressure of the working pressure chamber 9 decreases. As a result, the main diaphragm 8A is displaced downward, the main valve 5A opens the main port 2A, and the fluid pressure at the outlet 4 increases. If the pressure _P2 at outlet 4 becomes higher than the set value for some reason,
Since the pressure acts on the pressure chamber 15 through the passage 16, the servo diaphragm 12 is displaced upward, and the servo valve member 13A is moved into the pilot passage 14A.
move in the direction of closing. Therefore, the internal pressure of the working pressure chamber 9 increases, and the main diaphragm 8
The upward displacement of A causes the main valve 5A to operate in the direction of closing the main port 2A. Therefore, the fluid pressure _P2 at the outlet 4 is controlled to return to the set value.

FIG. 7 shows an example in which the above servo regulator is used in a composite gas valve. In the figure, 31 and 32 are an inlet port and an outlet port provided between the gas inlet 3 and the main port 2A and between the main port 2A and the outlet 4 in the valve body 1A. The ports 32 are provided with cutoff valves 35 and 36 that open and close these ports via return springs 33 and 34, respectively. Note that a main burner is connected to the outlet port 32. Also, 10 is a servo regulator,
It has the same configuration as that shown in FIG. Further, the main valve 5A and the main port 2A have substantially the same structure and function as described above. Note that 42 is a pilot burner passage provided between the inlet port 31 and the main port 2A.

Numerals 37 and 38 are bellows-flamm actuated pistons, and the above-mentioned shutoff valves 35 and 36 are attached to the ends of each of these pistons 37 and 38, respectively. 39 is an electromagnetic pump to which an oil tank 40 and a three-way electromagnetic valve 41 are connected as shown, and the piston 3
Oil is directly supplied to the bellows flamm of the piston 7 from an electromagnetic pump 39, and oil is supplied to the bellows flamm of the piston 38 through a three-way solenoid valve 41.

In such a composite gas valve, when a controller (not shown) drives the electromagnetic pump 39, oil not only flows through the electromagnetic valve 41 in the direction of arrow a, but also acts on the bellows flammable for operating the piston 37, thereby opening the shutoff valve 35. Gas entering the inlet port 31 is thus directed to the pilot burner via the pilot burner passage 42. When the gas from the pilot burner is ignited in this manner, the controller switches the solenoid valve 41 to flow the oil in the direction of arrow b and also causes it to act on the bellows flammable for actuating the piston 38. Therefore, the isolation valve 36 is opened and the gas entering the inlet port 31 is supplied to the main burner via the outlet port 32. During this operation, the controller applies a predetermined DC voltage to the piezoelectric actuator 23 of the servo regulator based on control calculations, determines the gas control pressure, and obtains a predetermined combustion amount.

FIG. 8 shows another embodiment of the composite gas valve. This is a valve body 1B that is a modified version of the valve body 1A shown in FIG.
Pilot valves 48 and 49, which are opened and closed by diaphragm-operated pistons 46 and 47, are in contact with the inlet port 43 and the outlet port 45, respectively. Further, a main valve 50 is provided in the main port 44 so as to be able to move toward and away from the main port 44, and the amount of displacement is automatically controlled by a diaphragm valve 51 that responds to gas pressure upstream and downstream of the main valve 50. 52 is a pilot burner passage. 39
A, 39B are a pair of electromagnetic pumps, 40A, 40B
is an oil tank, and 41A and 41B are three-way solenoid valves, each of which constitutes a hydraulic system similar to that shown in FIG. The bellow flams for actuating the pistons 37 and 38 each have a three-way solenoid valve 41.
Receives hydraulic pressure from A, 41B, pistons 46, 47
Each bellow frame for operation is an electromagnetic pump 39
It receives hydraulic pressure independently from A and 39B.

In such a composite gas valve, when a controller (not shown) drives the electromagnetic pumps 39A, 39B, oil flows through the three-way electromagnets 41A, 41B in the direction of the arrow a ₁ ,
In addition to flowing in _two directions, the hydraulic pressure is also applied to the belloframs for operating the pistons 46 and 47, and the pilot valves 48 and 49 both open the inlet port 43 and the outlet port 45. Therefore, the gas at the inlet 31 is led out to the pilot burner passage 52 through each port 43, 44, 45, and ignition is performed in the pilot burner. When this ignition is confirmed, the controller switches the electromagnetic circuits 41A and 41B to flow the oil in the directions of arrows b ₁ and b ₂ , and the piston 3
7,38 Supply hydraulic pressure to the bellow flammable for operation,
Open each cutoff valve 35, 36. Therefore, gas from the inlet 31 is supplied to the main burner through the outlet 32. In this case as well, the controller applies a predetermined DC voltage to the piezoelectric actuator 23 of the servo regulator based on control calculations, determines the gas control pressure, and obtains a predetermined combustion amount. Incidentally, an external view of the composite gas valve shown in FIG. 8 is shown in FIGS. 9 and 10.

[Effect of idea]

As described above, according to this invention, an electric-mechanical output is obtained by applying a DC voltage to the piezoelectric actuator, and this is applied to the servo diaphragm for adjusting the fluid control pressure of the servo regulator. The fluid control by the main valve can be automatically adjusted to a predetermined value by opening and closing the pilot passage using a responsive servo valve member and adjusting the pressure in the working pressure chamber separated by the main diaphragm. Therefore, it is possible to obtain an electrostrictive proportional operation type servo control valve that has a simple configuration and is inexpensive.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a servo control valve according to an embodiment of this invention, Fig. 2 is an explanatory view of a laminated piezoelectric actuator, Fig. 3 is an explanatory view of a series type pymorph type piezoelectric actuator, and Fig. 4 is an explanatory view of a series type pymorph type piezoelectric actuator. An explanatory diagram of a parallel type pimorph type piezoelectric actuator, Figure 5 is an explanatory diagram showing the displacement situation of the pimorph type piezoelectric actuator, Figure 6 is a sectional view showing another embodiment of the servo control valve, and Figure 7 is a composite gas 8 is a sectional view showing another application example, FIG. 9 is a partially cutaway front view of the composite gas valve shown in FIG. 8, and FIG. 10 is a partially cutaway view of the composite gas valve shown in FIG. FIG. 1 is the valve body, 2, 2A is the main port, 3 is the inlet, 4 is the outlet, 5, 5A is the main valve, 7 is the spring, 8,
8A is a main diaphragm, 9 is a working pressure chamber, 10 is a servo regulator, 12 is a servo diaphragm, 13 is a servo valve member, and 23 is a piezoelectric actuator.

Claims (1)

[Scope of utility model registration request] a valve body having an inlet and an outlet that communicate through a main port; a main valve that is biased in the closing direction by a spring and controls fluid pressure on the outlet side by changing the degree of opening of the main port; a servo diaphragm that responds to fluid pressure on the outlet side of the main valve; and a servo valve member that adjusts a working pressure in accordance with the fluid pressure on the outlet side with respect to the main diaphragm that supports the main valve by the operation of the servo diaphragm. and a piezoelectric actuator that electrostrictively displaces the servo diaphragm in response to a control signal input.