JPH0335951Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a gas proportional control valve used for proportional control of gas combustion, and in particular controls the gas supply amount to set the temperature of the controlled system to a desired set value. The present invention relates to a gas proportional control valve that can perform proportional control of gas supply without being affected by the furnace pressure of a combustion chamber to which gas is supplied via the gas proportional control valve.

<Prior Art> A gas proportional control valve used to control the amount of gas supplied to a combustion chamber in a gas combustion system is, for example, a hot water supply system in which a controller is used to maintain the hot water supply temperature at a predetermined temperature. The control mechanism of the gas proportional control valve is operated so that the valve opening degree for gas supply is proportionally varied in accordance with the control signal from the controller. That is, the control mechanism in the gas proportional control valve includes a servo regulator driven by an electromagnetic solenoid coil as a control unit that responds to control signals from the controller, and this servo regulator controls the pressure in the main diaphragm chamber. This proportionally controls the valve opening of the main valve that changes the opening area that separates the inlet passage on the gas supply side and the outlet passage on the combustion chamber side, and if the hot water temperature is lower than a predetermined set value, the opening of the main valve Increase the opening,
Increase the gas supply to increase combustion.

By the way, conventionally, in such a gas proportional control valve, the variation in the pressure inside the furnace in the combustion chamber where the burner is arranged is returned to the control mechanism of the gas proportional control valve through the gas supply pipe. A phenomenon has occurred in which control becomes unstable due to fluctuations in internal pressure. In other words, the combustion system in the combustion chamber, including the burner, is accompanied by pressure fluctuations in the furnace at a fairly high frequency, so if this pressure fluctuation is returned to the control mechanism of the gas proportional control valve as described above, the gas The control mechanism of the proportional control valve also responds to undesirable factors such as those mentioned above, and the opening degree of the main valve also changes, making it impossible to control the amount of supplied gas to a stable desired value.

<Problems to be solved by the invention> This invention solves the problem of proportional control being affected by fluctuations in the furnace pressure of the combustion chamber to which gas is supplied via the gas proportional control valve. This is an attempt to solve the problem of control being inhibited.

<Means and effects for solving the problem> This invention therefore uses a servo regulator driven by a magnetic circuit to control the pressure in the main diaphragm chamber to proportionally control the valve opening of the main valve. In the gas proportional control valve, the pressure inside the combustion chamber is introduced into the chamber opposite to the feedback chamber of the servo diaphragm constituting the servo regulator, and the chambers on both sides of the servo diaphragm control the servo This is designed to offset fluctuations in the furnace pressure applied to the diaphragm.

<Embodiment> An embodiment of this invention will be described below based on the drawings.

FIG. 1 shows the structure of a gas proportional control valve according to an embodiment of this invention, and FIG. 2 is a block diagram showing an outline of a gas combustion system using the gas proportional control valve.

First, an overview of the gas combustion system will be explained with reference to Fig. 2. 1 is a combustion chamber, 2 is a burner placed in the combustion chamber 1, 3 is a fan motor that supplies air to the combustion chamber 1, and 4 is not shown in the diagram. 5 is a gas proportional control valve comprising a valve body 6 and a control section 7; 8 is the fan motor 3, the shutoff valve 4, and the gas proportional control valve 5; This is a controller that sends control signals to the
In addition, in Figure 2, the pilot valve for the pilot flame,
An igniter for ignition, a flame sensor for detecting the lower edge 9, etc. are omitted.

Regarding the control of the shutoff valve 4 and fan motor 3 by the controller 8, the controller 8
Gas supply is started by opening the shutoff valve 4 in response to a control signal from the burner 2, and air is supplied by rotating the fan motor 3, so that combustion is performed by the burner 2. Regarding the control of the gas proportional control valve 5, the controller 8 performs control calculations based on a process value detected by a temperature sensor etc. provided in a controlled system (not shown) and a preset setting value. According to this calculation result, the gas supply amount is changed by proportionally controlling the opening degree of the above-mentioned gas proportional control valve 5, which is an operating device, to realize a desired temperature set value. In the gas proportional control valve 5 according to the invention, as shown in FIG. By doing so, even if the furnace pressure in the combustion chamber 1 fluctuates, the proportional control of gas supply is not affected by the fluctuations in the furnace pressure.

That is, in FIG. 1 showing the structure of the gas proportional control valve 5, 11 is an inlet passage connected to the gas supply source side, 12 is an outlet passage connected to the combustion chamber 1 side, and 13 is the inlet passage 11. This is a main valve for changing the opening area that partitions the outlet passage 12, and the main valve 13 is pressed by a spring 14 in the direction of closing the main port 15. 16 is the above-mentioned entrance passage 1
A bypass passage (bypass passage) provided to communicate between 1 and the outlet passage 12, 17 a servo diaphragm provided in the middle of the bypass passage 16, and 18 a servo section disposed in the servo diaphragm 17. The servo valve member 18 is adapted to change the constricted area of the bypass passage 16 in response to a control signal from the controller 8. That is, 19 is an electromagnetic solenoid coil to which a direct current is applied as a control signal from the controller 8, and 20 is a plunger that displaces the servo valve member 18 in the vertical direction in the figure. Upon activation, the servo valve member 18 narrows or widens the pilot passage 21. Further, since the servo diaphragm 17 is provided in the bypass passage 16, the gas control pressure in the outlet passage 12 is fed back to the feedback chamber 22 of the servo diaphragm 17 via the bypass passage 16. Therefore, the servo diaphragm 17 constitutes a servo regulator that functions to keep the gas control pressure constant.

23 is a passage branched from the bypass passage 16; 24 is a main diaphragm for opening the main valve 13 against the spring 14; 25 is a pressure chamber formed by the main diaphragm 24, that is, a main diaphragm chamber; The passage 23 communicates with the main diaphragm chamber 25, and the pressure in the main diaphragm chamber 25 is controlled according to the displacement of the servo valve member 18, and when the pressure increases, the opening degree of the main valve 13 is increased. On the other hand, the valve opening degree of the main valve 13 is proportionally controlled so that if it decreases, the valve opening degree is decreased. Furthermore, a chamber 26 is formed in the upper part of the servo diaphragm 17 in which the servo valve member 18 is disposed, and the above-mentioned furnace pressure detection tube 10 is connected to this chamber 26 via a connecting portion 27, and the servo regulator is connected to the chamber 26. The furnace pressure of the combustion chamber 1 is introduced into the chamber 26 which faces the feedback chamber 22 of the servo diaphragm 17 constituting the combustion chamber. That is, by the servo diaphragm 17,
The internal pressure of the bypass passage 16 and the furnace internal pressure from the combustion chamber 1 are separated, and the servo diaphragm 17
The feed pack chambers 22 and 26 on both sides of the chamber 22 and 26 are arranged to compensate for fluctuations in pressure within the furnace.

Next, the operation of the gas proportional control valve 5 having the above configuration will be explained.

When a DC current is applied as a control signal from the controller 8 to the electromagnetic solenoid coil 19 to excite it, the plunger 20 is pushed down in accordance with the magnitude of the DC current. In other words, if the deviation between the process value and the set value is large and there is a demand for increased combustion,
A direct current of a magnitude corresponding to the above deviation is applied,
The plunger 20 is pushed down further as the DC current increases. When the plunger 20 is pushed down,
The servo diaphragm 17 is pressed and the pilot path 21 becomes narrower. When the pilot passage 21 becomes narrower, the gas pressure in the inlet passage 11 acts on the main diaphragm chamber 25 through the passage 23 communicating with the main diaphragm chamber 25 as a result of the narrowing of the passage leading to the bypass passage 16. 25 pressure increases. When the pressure in the main diaphragm chamber 25 increases, the main diaphragm 24 pushes up the main valve 13 against the spring 14, so the main port 15 is opened more widely. Therefore, the gas control pressure in the outlet passage 12 increases to a predetermined value, increasing combustion.

Also, here, the gas control pressure in the outlet passage 12 is fed back to the feedback chamber 22 of the servo diaphragm 17 via the bypass passage 16, so the gas control pressure corresponds to the magnitude of the DC current. It is controlled so that it remains constant. That is, for example, if the gas control pressure increases for some reason, the pressure in the feedback chamber 22 increases, so the servo diaphragm 1
7 is pushed up, and the pilot passage 18 is widened.
When the pilot passage 18 widens, the pressure in the main diaphragm chamber 25 decreases in accordance with the operation opposite to the above, and the main valve 13 is controlled in the direction in which the main port 15 closes, so that the gas control pressure is returned to its original state. Become. In this way, the gas proportional control valve 5 can obtain a gas control pressure that is approximately proportional to the DC current applied to the electromagnetic solenoid coil 19, and furthermore, the gas control pressure can be adjusted to the furnace pressure in the combustion chamber 1. can be maintained without being affected by fluctuations in

That is, when the furnace pressure in the combustion chamber 1 fluctuates, the fluctuation in the furnace pressure is transmitted to the outlet passage 12 through the burner 1 and returned to the gas proportional control valve 5.
At the same time, the furnace pressure is also introduced into the chamber 26 via the furnace pressure detection tube 10. Therefore, when the furnace pressure in the combustion chamber 1 oscillates, in the conventional case, the pressure in the footback chamber 22 also oscillates in synchronization with the fluctuations in the furnace pressure, and the servo diaphragm 17 vibrates to maintain good proportionality. In contrast, in the above configuration, the furnace pressure guided by the furnace pressure detection tube 10 is introduced into the chamber 26 opposite to the feedback chamber 22 with the servo diaphragm 17 in between. , the upper and lower chambers 26 of the servo diaphragm 17 and the feedback chamber 22 can exactly cancel pressure fluctuations in the furnace pressure. Therefore, even if the furnace pressure in the combustion chamber 1 fluctuates, it is possible to prevent the above-mentioned proportional control from being affected by such undesired pressure fluctuations, and it is possible to realize good proportional control and supply The gas amount is controlled to a stable desired value.

<Effects of the invention> As described above, according to this invention, the servo diaphragm that faces the feedback chamber of the servo diaphragm that constitutes the servo regulator of the gas proportional control valve driven by the control signal from the controller. Since a chamber is formed and the furnace pressure of the combustion chamber is introduced into this chamber, even if the furnace pressure fluctuates, the fluctuations in the furnace pressure applied to the servo diaphragm can be offset, and the combustion chamber The amount of supplied gas can be controlled to a stable predetermined value according to the control signal without being affected by the pressure in the furnace.

[Brief explanation of drawings]

FIG. 1 is a structural diagram showing an embodiment of the gas proportional control valve of this invention, and FIG. 2 is a schematic structural diagram of a gas combustion system using the gas proportional control valve. DESCRIPTION OF SYMBOLS 1... Combustion chamber, 5... Gas proportional control valve, 6... Valve body, 7... Control part, 10... Furnace pressure detection tube, 11...
Inlet passage, 12... Outlet passage, 13... Main valve, 14...
Spring, 15... Main port, 16... Passage for bypass, 17... Servo diaphragm, 18... Servo valve member, 19... Electromagnetic solenoid coil, 20... Plunger, 22... Feedback chamber, 23
...passage, 24...main diaphragm, 25...main diaphragm chamber, 26...chamber, 27...connection section.

Claims (1)

[Scope of utility model registration request] A valve body having an inlet passage on the gas supply source side and an outlet passage on the combustion chamber side, and a valve for changing the opening area that partitions the inlet passage and the outlet passage of this valve body, and is pressed in the normally closed direction. The main valve and
A main diaphragm for opening the main valve against the pressing force in the normally closed direction, a first bypass passage communicating the inlet passage and the outlet passage of the valve body, and the first passage. a second passage that branches and communicates with the pressure chamber formed by the main diaphragm; and a servo diaphragm that is provided in the first passage and separates the internal pressure of the first passage and the furnace internal pressure from the combustion chamber. , means for introducing the furnace internal pressure into a chamber opposite to the feedback chamber formed by the servo diaphragm; a servo valve member disposed on the servo diaphragm for changing the throttle area of the first passage; A gas proportional control valve comprising a magnetic circuit that controls the force applied to a servo diaphragm via a plunger.