JPS629785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control valve provided for controlling the flow rate of fuel gas.

Conventionally, as disclosed in Japanese Utility Model Publication No. 55-16172, there is an actuator that supplies pressurized fluid to a pressure chamber using an electromagnetic pressure feeding device and controls the return flow rate to adjust the pressure within the pressure chamber.

However, when the above actuator is applied to a control valve that controls the flow rate of fuel gas supplied to various types of gas combustors, if the flow rate falls below the minimum value determined by the characteristics of the burner, the turn
There was a problem that phenomena such as downing occurred, making it impossible to maintain normal combustion conditions, resulting in dangerous conditions such as the release of unburned gas.

This invention was made to solve the above-mentioned problems, and is provided with an actuator that controls a valve body by the pressure of fluid pumped by an electromagnetic pumping device. It is an object of the present invention to provide a control valve that controls the supply flow rate so that it does not fall below a predetermined minimum value.

In order to achieve the above-mentioned object, the present invention includes an electromagnetic pressure-feeding device for force-feeding fluid into a pressure chamber, and an electromagnetic pressure-feeding device for force-feeding a fluid into a pressure chamber, and an electromagnetic force-feeding device for force-feeding a fluid into a pressure chamber. a pilot valve that adjusts the pressure in the pressure chamber; a responsive body that senses the pressure in the pressure chamber and displaces; A valve body that controls pressure, a pressure sensor that detects the pressure in the outlet passage, and a control signal corresponding to the deviation between the output signal of the pressure sensor and the set value is supplied to the pilot valve, and a control circuit for controlling the position of the valve body so that the pressure of the pressure sensor reaches a set value, and the control circuit controls a predetermined constant value when the output signal of the pressure sensor is less than or equal to a predetermined value. A minimum set pressure limiting circuit is provided for supplying a minimum output signal to the pilot valve.

The control valve according to the present invention is a valve body that uses an electromagnetic pressure feeding device to forcefully feed fluid into a pressure chamber, and opens and closes a port between an inlet passage and an outlet passage by a responsive body that senses the pressure in the pressure chamber and displaces the fluid. A control signal corresponding to the deviation between the detected value of the pressure sensor that detects the pressure in the outlet passage and the set value is supplied from the control circuit to the pilot valve that regulates the pressure in the pressure chamber, and the output is outputted. The position of the valve body is controlled so that the pressure in the passage becomes the set value, and when the detected value of the pressure sensor is less than a predetermined value, a predetermined constant minimum output signal is sent from the minimum set pressure limiting circuit. By supplying the fuel gas to the pilot valve, the flow rate of the fuel gas supplied to the burner from the outlet passage does not fall below a predetermined minimum value, and a normal combustion state can be safely maintained.

Next, an embodiment of the present invention will be described with reference to the drawings. The valve body designated by reference numeral 1 in FIG. ,
The pressure of the fuel gas in the outlet passage 4 is controlled. In order to detect this pressure, a pressure sensor 6 is provided which generates an output signal corresponding to the pressure within the outlet passage 4.

Actuator 2 has an electromagnetic pump 22 housed within a casing 21 . This electromagnetic pump 2
2 receives a drive signal supplied to the coil 23 from a drive circuit (not shown), and pressure-feeds the liquid (for example, oil) contained in the first chamber 24 formed in the casing 21 to the second chamber 25. work like this,
The pressure within the second chamber 25 causes a responsive body 27 connected to the valve body 1 via a rod 26 to be displaced. Further, a communication path 28 is provided for returning the fluid in the second chamber 25 to the first chamber 24,
A predetermined resistance is applied to the fluid flowing through the communication path 28 by a pilot valve 8, which will be described later.

Therefore, when a drive signal is supplied from the drive circuit, the electromagnetic pump 22 pumps the liquid in the first chamber 24 to the second chamber 25 to increase the internal pressure, and senses this increase in pressure. The response body 27 moves downward in the figure. Due to this movement of the response body 27, the valve body 1
descends against the spring 7, increasing the opening area of the port 5. Further, when the pressure in the second chamber 25 decreases, the valve body 1 rises together with the responsive body 27 due to the action of the spring 7, thereby reducing the opening area of the port 5. By this movement of the valve body 1, the outlet passage 4
The gas pressure inside is controlled, and this gas pressure is detected by a pressure sensor 6. Under normal conditions, gas pressure is proportional to the gas supply flow rate.

FIG. 2 shows another form of actuator 2 applicable to the present invention. In this example, an electromagnetic compressor 32 for pumping air into a pressure chamber 31 corresponding to the second chamber 25 is used in place of the electromagnetic pump 22 shown in FIG. This electromagnetic compressor 32 has a coil 33 to which a drive signal is supplied, and a cylindrical body 35 that supports a plunger 34 that reciprocates at the center of the coil 33. A piston 36 movable within a cylinder 35 is connected to the plunger 34.
By the reciprocating motion of 6, the inside of the cylinder chamber 37 formed in the cylinder 35 is alternately pressurized and depressurized. This cylinder chamber 37 has a check valve 38 and a check valve 38, respectively.
The suction chamber 40 is connected to a suction chamber 40 and a discharge chamber 41 containing a
Further, the discharge chamber 41 is connected to the pressure chamber 31 through the communication hole 43.
are connected to each other. The discharge chamber 41 also communicates with the outside via a passage 44 and a pilot valve 8. Further, the check valve 38 is pressed by a spring 45 in the direction of closing the suction hole 42, and the check valve 39 is pressed by the spring 45 in the direction of closing the passage between the cylinder chamber 37 and the discharge chamber 41.
6.

A plunger 34 and a piston 36 connected thereto are driven by a drive signal supplied to the coil 33.
When the pressure chamber 31 reciprocates, air sucked through the suction hole 42 is forced into the pressure chamber 31, and the pressure inside the chamber 31 increases. That is, when the piston 36 moves upward in FIG. Air is inhaled. Also piston 36
In the process of descending, the air in the cylinder chamber 37 and the suction chamber 40 is compressed, so the check valve 38 is held in the position where the suction hole 42 is closed.
The check valve 39 moves against the spring 46 and opens a passage between the cylinder chamber 37 and the discharge chamber 41. As a result, the air in the cylinder chamber 37 is
Pressure chamber 31 through discharge chamber 41 and communication hole 43
A portion of the fluid flows into the interior and a portion is discharged to the exterior through the passage 44. When the pressure inside the pressure chamber 31 increases due to this operation, the responsive body 27 is pushed down, and the valve body 1 connected to the responsive body 27 via the rod 26 moves in the opening direction, as in the case of FIG. .

From the second chamber 25 to the first chamber 24 through the communication path 28
The pilot valve 8 for providing a predetermined resistance to the fluid returned to the pipe includes a coil 9 to which a DC control signal is supplied from a control circuit 14, which will be described later, and a coil 9.
The plunger 10 is movable in the axial direction at the center of the plunger 10. One end of the plunger 10 supports a valve body 12 via a diaphragm 11, and adjusts the opening area of a passage 13 connected to the second chamber 25 depending on the position of the valve body 12. That is, the pilot valve 8 controls the first valve from the second chamber 25 through the communication passage 28 in response to a control signal supplied from the control circuit 14.
By adjusting the amount of resistance given to the fluid returning to the chamber 24, the pressure within the second chamber 25 is adjusted, thereby changing the degree of opening of the valve body 1.

On the other hand, the control circuit 14 includes an arithmetic control circuit 15, a minimum set pressure limiting circuit 16, and a maximum set pressure limiting circuit 17. Based on the output of the comparator 18 that compares the set value SP given from the outside with the output signal of the pressure sensor 6, the arithmetic control circuit 15 calculates
An output signal corresponding to this output is generated, and this output signal is supplied to the pilot valve 8 as a control signal.

The output signal of the pressure sensor 6 is also simultaneously supplied to the minimum set pressure limiting circuit 16 and the maximum set pressure limiting circuit 17. The minimum set pressure limiting circuit 16 reduces the pressure to the minimum value when the pressure in the outlet passage 4 becomes lower than a predetermined minimum value due to the set value SP being set to a significantly low value. The control signals necessary to maintain the pilot valve 8 are supplied to the pilot valve 8.
This minimum value is preset to a value that does not cause the burner to turn down, depending on the characteristics of the burner supplied with fuel gas through the outlet passage 4. However, when the source pressure decreases and the minimum pressure cannot be achieved even if the valve body 1 is opened, the valve body 1
Turn off. On the other hand, when the pressure inside the outlet passage 4 becomes higher than a predetermined maximum value due to the set value SP being set to a significantly high value, the maximum set pressure limiting circuit 17 controls the pressure to a predetermined value. A drive signal limiting the value is given to the pilot valve 8 with priority over the output of the arithmetic control circuit 15. This prevents the danger of excessive fuel gas being supplied to the burner, but in cases where the maximum pressure is limited by a regulator or the like, the maximum set pressure limiting circuit 17 Can be omitted.

As described above, according to the present invention, no matter how the set value is changed, the flow rate of the fuel gas supplied to the burner from the outlet passage 4 will never fall below a predetermined minimum value, and for example, the It is also safe to control combustion manually using, for example,

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view including a block diagram showing the configuration of a control valve according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of another actuator that can be applied to the control valve of FIG. 1. DESCRIPTION OF SYMBOLS 1... Valve body, 2... Actuator, 3... Inlet passage, 4... Outlet passage, 5... Port, 6... Pressure sensor, 8... Pilot valve, 9... Coil,
10...Plunger, 11...Diaphragm, 1
2... Valve body, 13... Passage, 14... Control circuit,
15... Arithmetic control circuit, 16... Minimum setting pressure limiting circuit, 17... Maximum setting pressure limiting circuit, 18... Comparator, 22... Electromagnetic pump, 23... Coil, 2
4...First chamber, 25...Second chamber, 26...Rod, 27...Response body, 31...Pressure chamber, 32...
Electromagnetic compressor, 33...coil, 36...piston.

Claims (1)

[Claims] 1. An electromagnetic pressure-feeding device for force-feeding fluid to the pressure chamber, and adjusting the pressure in the pressure chamber by adjusting the amount of resistance given to the fluid flowing out from the pressure chamber. A pilot valve, a responsive body that senses the pressure in the pressure chamber and displaces, and a valve that displaces together with the responsive body to control the pressure in the outlet passage of the controlled fluid flowing from the inlet passage to the outlet passage. and a pressure sensor that detects the pressure in the outlet passage, and a control signal corresponding to the deviation between the output signal of this pressure sensor and the set value is supplied to the pilot valve, and the pressure in the outlet passage is adjusted to the set value. and a control circuit for controlling the position of the valve body so that the pressure sensor outputs a predetermined constant minimum output signal when the output signal of the pressure sensor is less than or equal to a predetermined value. A control valve further comprising a minimum set pressure limiting circuit that supplies a pilot valve. 2 The drive circuit further includes a maximum set pressure limiting circuit that supplies a predetermined constant maximum output signal to the pilot valve when the output signal of the pressure sensor becomes larger than a predetermined value. A control valve according to claim 1.