JPS58178117A - Proportioning controller for gas combustion - Google Patents

Abstract

PURPOSE:To relieve a demand precision of a working pressure detector and to increase a combustion range TDR (rated maximum combustion flow rate/minimum combustion flow rate) under a condition that a detecting range output ratio is high, by controlling a gas pressure control valve with the aid of a pressure detector for detecting a difference in pressure between the upstream and the downstream of a variable throttle mechanism. CONSTITUTION:In case a combustion quantity is gradually choked from a rated maximum combustion condition, or, for example, when a hot water feed amount is reduced or if temperature of hot water is set to a low value, an electric signal from a temperature detector 7 or an electric signal from a temperature setting part 14 is compared for decision by a control operating part 15 to output it as a temperature deviation signal 16 to a variable throttle mechanism 4A. Thereafter, an operation is conducted so that the size of the flow path equivalent sectional area of the variable throttle mechanism 4A is gradually changed into a value opposing to the temperature deviation signal 16. Meanwhile, a value of a pressure detector 10 varies with a change in the value of the flow path equivalent sectional area to output an electric signal 17 which is processed as a control signal of a gas pressure control valve 3 by means of an electric control circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a means for expanding the combustion output range of gas combustion equipment, particularly gas water heaters. There is. That is, in the gas system, a first solenoid valve 1, a second solenoid valve 2, and a gas pressure control valve 3 are connected in series, and a fixed nozzle 4 is further connected to the gas pressure control valve 3 to control the controlled fuel gas. is supplied to the premix burner 5.

A heat exchanger 6 is disposed above or below the presynchronization burner 6, and the heat exchanger 6 exchanges heat of the combustion gas in order to turn water into hot water. A temperature detector 7 is attached to the outlet of the heat exchanger 6, and its electric signal is led to an electric control circuit (I) 9 for the fan 8.

Reference numeral 10 denotes a pressure detector that detects the differential pressure between a location of the blower pipe 11 of the fan 8 and the fuel gas and air mixing section 12, and an electrical signal from this pressure detector 10 is transmitted to the gas pressure control valve. fil) 13.

In the above configuration, a case where the combustion amount is sequentially reduced from the rated maximum combustion state will be explained using FIGS. 1 and 2.

In other words, for example, if the amount of hot water is decreased, the temperature sensor 7
A certain electrical signal for reducing the airflow rate of the fan 8 is inputted to the electric control circuit (■) 9, thereby reducing the airflow rate of the fan 8. Therefore, an electric signal corresponding to the change in the air flow rate is generated in the pressure detector 10, and this electric signal is immediately transmitted to the electric control circuit ([) 13 for the waste pressure control valve 3 to drive the waste pressure control valve 3. j The gas control valve 3 is controlled so that the combustion gas is processed by the electricity No. 16 and corresponds to the amount of air blown.

In FIG. 2, the horizontal axis represents the differential pressure ΔP of the pressure detector 10, and the vertical axis represents the combustion flow rate Q (air flow rate in this conventional example). For example, if you reduce the combustion amount to qmin by reducing the amount of hot water as explained above from the state of the rated maximum combustion amount qmax, for example, TDR = qmln / qmax = 1
/15, the pressure difference Δ between the combustion flow Ho and the pressure detector 10
Since there is a Qa relationship between P, JP at qmin
is 1/26 of qm a X, for example, qmax
If the JP at the time is 50wnH2O, the JP at the time of qmln becomes 2H20.

Also, when trying to reduce the amount of qmin/qma9m mini-1/1 burnt, JP at qmin is 1/100 of qmax.
It needs to be controlled to a minimum. In other words, as in the previous example, when JP is 60㎥ H2O when qrna is used, qm
The dpo value at the time of in needs to be controlled to a very small value of o, s wn H20, and the pressure detector 10 is required to have strict accuracy. Therefore, when trying to accurately control the flow of combustion gas by changing the pressure of the pressure detector 10, the accuracy required for the pressure detector becomes stricter as "D" = qmin/qmax becomes smaller, so it is not practical. has a TDR of 1
A value of /3 to 1/6 was the limit value.

The present invention solves the above-mentioned conventional drawbacks by increasing the combustion range TDR by relaxing the required accuracy of the working pressure detector or by setting the detection range output ratio ΔPm1n/"maX to a value as large as possible. This is the purpose.

In order to achieve this purpose, the present invention uses a temperature detector that detects the hot water temperature and a temperature deviation signal from the temperature setting section.
It has a variable throttle mechanism that controls the amount of gas burned, and is equipped with a pressure sensor that detects the differential pressure between the upstream and downstream sides of the variable throttle mechanism. It is configured to control.

With this configuration, a variable throttle mechanism is used to control the amount of gas combustion based on the temperature deviation signal, that is, 1. By varying the flow passage cross-sectional area of the nozzle or orifice, the pressure control characteristics of the combustion flow rate itself can be changed across the board, making it possible to easily expand the combustion control range TL)H.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 6. Note that parts in FIG. 3 that are the same as those in FIG. 1 are marked with the same numbers.

In FIG. 3, 4A is a variable throttle mechanism in which the cross-sectional area of the flow path is variably controlled in response to a temperature deviation signal; 14 is a temperature setting unit;
Reference numeral 16 denotes an adjustment operation section consisting of a comparison section and a judgment section, 16 a temperature deviation signal, and 17 an electric signal.

In FIGS. 4 and 6, the horizontal axis represents the differential pressure ΔP of the pressure detector 10, and the vertical axis represents the combustion flow rate Q, indicating the pressure control characteristics of the combustion flow rate.

φ1 to φ6 (or φ6 in Figure 5) represent the equivalent cross-sectional area of the flow path of the variable throttle mechanism with symbols, and φ1 is the size of the equivalent cross-sectional area of the flow path of the variable throttle mechanism at the maximum rated combustion. be. Below φ2. The equivalent cross-sectional area of the flow path becomes smaller as the diameter increases to φ3.

Further, curves a-e in FIG. 4 are pressure control characteristic curves of combustion flow rate corresponding to φ1 to φ6, respectively. And (a) is the pressure detector 10 at the maximum rated combustion.
, (b) is the differential pressure at the minimum TDR in the present invention, ←→ is the pressure difference when using the conventional fixed nozzle (therefore, the pressure control characteristic curve of the combustion flow rate is only a). It shows the value of the differential pressure at the minimum TDR.

In the above configuration, a case where the combustion amount is sequentially reduced from the rated maximum combustion state will be explained. Namely.

For example, when the amount of hot water discharged or the temperature of hot water discharged is set low, the electric signal from the temperature detector 7 or the electric signal from the temperature setting section 14 is compared and determined by the adjustment operation section 16, and the temperature deviation signal 16 It is output to the 4A variable aperture mechanism.

Then, the area of the flow path equivalent cross-sectional area of the variable throttle mechanism 4A is φ
Temperature deviation signal 1 sequentially from 1 to φ2 or further to φ3
On the other hand, as the value of the flow path equivalent cross-sectional area φ1 changes, the value of the pressure sensor 10 also changes, and an electrical signal 17 is output. This electric signal 17 is processed by the electric control circuit ([1) 13 as an operation signal for the gas pressure control valve 3 and at the same time, the pressure sensor 1
The gas pressure is outputted to the gas pressure control unit [3] so that the differential pressure at zero becomes smaller and the amount of combustion is reduced.

That is, in FIG. 4, when the curve a is on the pressure control characteristic curve of the combustion flow rate and the rated maximum combustion amount qmax of the flow path equivalent cross-sectional area of φ1 is reached, the value of the pressure sensor 10 is (a).
In this case, when the amount of hot water discharged is reduced or the temperature of hot water discharged is reset to a lower value, conventionally, the combustion flow rate changes along the pressure control characteristic curve of curve a, but in the present invention, the flow rate of the variable throttle mechanism changes. Since the pressure is controlled in the direction in which the equivalent cross-sectional area of the road decreases 11th from φ1 and in the direction in which the differential pressure JP of the pressure sensor 10 decreases, F in FIG. 4 is controlled along the straight line. .

Therefore, as is clear from FIG. 4, the minimum control pressure corresponding to the minimum combustion flow rate value qmin, which was conventionally 0→, becomes a large value as shown in (b) in the present invention.

In addition, in this case, only the flow path equivalent cross-sectional area changes sequentially from φ1, so that the differential pressure detected by the pressure detector 10, that is, the differential pressure ΔP upstream and downstream of the variable throttle mechanism becomes constant.
When the gas pressure control valve is controlled, the differential pressure is kept constant at (a)', ie, the pressure at the maximum rated combustion time, as shown in FIG. 5, and is controlled along the straight line G.

Next, FIG. 6 shows an example of a specific configuration of the variable diaphragm mechanism 4A shown in FIG. 3.

101 is a variable throttle mechanism main body, 102 is a valve seat, 103 is a valve shaft, and 104 is an O-ring. Valve stem 103 and gear A1
05 and a stepping motor 106 are coaxially connected. Then, from gear A106 to gear B107
A potentiometer 108 is arranged to be rotationally driven via the .

As is clear from FIG. 6, the stepping motor 106 is rotated in response to the temperature deviation signal 16, and therefore the gap formed between the valve seat 102 and the valve shaft 103, that is, the equivalent cross-sectional area of the flow path. is changed, and the gas fuel flow rate is controlled as described above.

As is clear from the explanation in F below, the gas combustion proportional control device of the present invention is equipped with a variable throttle mechanism that controls the amount of gas combustion based on the temperature deviation signal of the tapping temperature, and the upstream and downstream of the variable throttle mechanism is By detecting the differential pressure with a pressure detector and controlling the gas pressure control valve with this pressure detection signal,
Compared to the conventional fixed nozzle system, it is no longer necessary to control the pressure to a small value, and therefore the accuracy of gas fuel flow rate control is significantly improved. and the minimum combustion flow rate qmin,
The so-called TDR (qm1n/qrna ratio) can be significantly reduced.The change is that the combustion output adjustment range can be expanded to a greater extent than before.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram of a conventional gas combustion proportional control device, Fig. 2 is a pressure control characteristic diagram of combustion flow rate in the conventional gas combustion proportional control device, and Fig. 3 is a gas combustion proportional control device according to an embodiment of the present invention. A schematic system diagram of the combustion proportional control device, FIGS. 4 and 6 are fuel flow rate pressure control characteristic diagrams of the present invention, and FIG. 6 is an embodiment of the variable throttle mechanism in the present invention. 3...Gas pressure control valve, 4A...Variable throttle mechanism, 7...Temperature detector, 10...
・Pressure detector, 14...Temperature setting section, 16...
...Temperature deviation signal, 17...Electrical signal. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
84 fI! j2 Figure @4 Figure 3 Figure 3 Figure 5

Claims (7)

[Claims] (1) It has a temperature detector that detects the outlet temperature of the gas water heater and a variable throttle mechanism that controls the amount of gas burned based on the temperature deviation signal from the temperature setting section, and the difference between the upstream and downstream of this variable throttle mechanism. A gas combustion proportional control device comprising a pressure sensor for detecting pressure, a gas pressure control valve controlled by an electric signal from the pressure sensor, and arranged in series with the variable throttle mechanism. (2) The gas combustion proportional control device according to claim 1, wherein the gas pressure control valve is controlled so that the differential pressure between the upstream and downstream sides of the variable throttle mechanism is kept constant. (3) The gas combustion proportional control device according to claim 1, wherein the amount of air necessary for combustion is simultaneously controlled by a temperature deviation signal that operates a variable throttle mechanism. (4) The variable throttle mechanism is provided with a position detection means corresponding to the amount of throttle, and the waste pressure control valve is controlled from the electric signal output from the position detection means and the differential pressure electric signal upstream and downstream of the variable throttle mechanism. A gas combustion proportional control device according to claim 1, wherein the gas combustion proportional control device is configured to: (5) The gas combustion proportional control device according to claim 4, wherein the air flow is controlled by a position detection signal corresponding to the throttle amount. (6) Gas combustion proportional control device 1 according to claim 1, configured to be able to control the variable throttle mechanism steplessly; (7) The gas combustion proportional control device according to claim 1, which is configured to control the variable throttle mechanism in multiple stages.