JPS6331694B2 - - Google Patents

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.

A conventional gas water heater is constructed as shown in FIG. 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 premix burner 5, 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 electrical signal is led to an electrical control circuit () 9 for the fan 8.

Reference numeral 10 denotes a pressure detector that detects the differential pressure between the blow 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. It is led to an electric control circuit ( ) 13 for 3.

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.

That is, for example, when the amount of hot water dispensed is decreased, an electrical signal for reducing the amount of air blown by the fan 8 is inputted from the temperature sensor 7 to the electric control circuit ( ) 9, and the amount of air blown by the fan 8 is decreased. Therefore, an electric signal corresponding to the change in air flow rate is generated in the pressure detector 10, and this electric signal is immediately used to drive the gas pressure control valve 3 in the electric control circuit ( ) 13 for the gas pressure control valve 3. The gas control valve 3 is processed into an electrical signal to control the gas control valve 3 so that the combustion gas 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). If we reduce the combustion amount from the current rated maximum combustion amount q _nax to q _nio by reducing the amount of hot water as explained above, for example, TDR =
When q _nio /q _nax = 1/5, there is a relationship of Q∝√ between the combustion flow rate Q and the differential pressure ΔP of the pressure detector 10, so ΔP when q _nio is 1/25 of q _nax For example, if ΔP when q _nax is 50 mmH ₂ O, ΔP when q _nio is 2 mmH ₂ O.

In addition, in order to reduce the combustion amount to q _nio /q _nax = 1/10, ΔP at the time of q _nio needs to be controlled to be as small as 1/100 of q _nax . That is, as in the previous example, if ΔP is 50 mmH ₂ O when q _nax , the value of ΔP when q _nio needs to be controlled to a very small value of 0.5 mmH ₂ O, and the pressure sensor 10 requires strict precision. Therefore, when trying to accurately control the combustion flow rate by changing the pressure of the pressure detector 10, the accuracy required for the pressure detector becomes stricter as TDR = q _nio /q _nax becomes smaller, so it is not practical. The limit value was a TDR of 1/3 to 1/5.

The present invention solves the above-mentioned conventional drawbacks,
The purpose is to increase the combustion range TDR by relaxing the required accuracy of the pressure detector used or by setting the detection range output ratio Δq _nio /Δq _nax to a value as large as possible.

In order to achieve this object, the present invention has a temperature detector that detects the hot water temperature and a variable throttle mechanism that controls the amount of gas combustion based on the temperature deviation signal from the temperature setting section, and upstream of this variable throttle mechanism. A pressure sensor is provided to detect the differential pressure between the gas pressure sensor and the downstream pressure, and the gas pressure control valve is controlled by an electrical signal from the pressure sensor.

With this configuration, the temperature deviation signal can be used to control the gas combustion amount by varying the cross-sectional area of the variable throttle mechanism, that is, the nozzle or orifice, thereby controlling the pressure control characteristics of the combustion flow rate. This makes it possible to easily expand the combustion control range TDR.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 3 to 6. Note that parts in FIG. 3 that are the same as those in FIG. 1 are given the same numbers.

In FIG. 3, 4A is a variable throttle mechanism 14 in which the cross-sectional area of the flow path is variably controlled in response to a temperature deviation signal.
15 is a temperature setting section, 15 is an adjustment operation section consisting of a comparison section and a judgment section, 16 is a temperature deviation signal, and 17 is an electric signal.

In FIGS. 4 and 5, the horizontal axis shows the differential pressure ΔP of the pressure detector 10, and the vertical axis shows the combustion flow rate Q, which is the pressure control characteristic of the combustion flow rate.

φ ₁ to φ ₅ (or φ ₆ in Fig. 5) represent the equivalent cross-sectional area of the flow path of the variable throttle mechanism with symbols, and φ ₁ is
This is the size of the equivalent cross-sectional area of the flow path of the variable throttle mechanism at the time of maximum rated combustion. Below, as φ ₂ , φ _{3 .} . . , the equivalent cross-sectional area of the flow path becomes smaller.

Moreover, curves a to e in FIG. 4 are φ ₁ to _{φ 5}
2 is a pressure control characteristic curve of combustion flow rate corresponding to each of the following. A is the differential pressure of the pressure detector 10 at the time of maximum rated combustion, and B is the TDR in the present invention.
The differential pressure at the minimum time, c, shows the value of the differential pressure at the minimum TDR when the conventional fixed nozzle is used (therefore, the combustion flow rate pressure control characteristic curve is only a). .

In the above configuration, a case where the combustion amount is sequentially reduced from the rated maximum combustion state will be explained. That is,
For example, when the amount of hot water discharged is decreased or the hot water temperature is set low, the electric signal from the temperature detector 7 or the electric signal from the temperature setting section 14 becomes 15.
The temperature deviation signal 1 is compared and judged in the adjustment operation section of
6, 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 changed from φ ₁ to φ ₂ or further to φ ₃ to a value corresponding to the temperature deviation signal 16 sequentially. On the other hand, as the value of the flow path equivalent cross-sectional area φ ₁ 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 () 13 as an operation signal for the gas pressure control valve 3, and at the same time, the gas pressure control valve 3 This is what is output to.

That is, in FIG. 4, on the combustion flow rate pressure control characteristic curve a, when the rated maximum combustion amount q _nax of the flow path equivalent cross-sectional area of φ ₁ , the value of the pressure sensor 10 is i. In the past, when the amount of hot water discharged was reduced or the temperature of hot water discharged was reset to a lower value, the combustion flow rate would change along the pressure control characteristic curve of curve a, but in the present invention, the flow path of the variable throttle mechanism changes. Since it is controlled in the direction in which the equivalent cross-sectional area decreases sequentially from φ ₁ and in the direction in which the differential pressure ΔP of the pressure sensor 10 decreases, it is controlled substantially along the straight line F in FIG. 4.

Therefore, as is clear from FIG. 4, the minimum control pressure corresponding to the minimum combustion flow rate value q _nio , which was conventionally C, becomes a large value as B in the present invention. In other words, the variable diaphragm mechanism 4A
As shown in the figure, the pressure flow rate control characteristics of the combustion flow rate have been changed, and the minimum combustion flow rate value q _nio can be controlled at a pressure Δp greater than the conventional one (c on the curve a), as shown in b on the curve e. Therefore, pressure detectors do not require high accuracy. In other words, even if the same pressure detector is used as before, the minimum combustion flow rate q _nio
can be controlled to a smaller extent.

In addition, in this case, only the flow path equivalent cross-sectional area changes sequentially from φ ₁ , and the gas is When the pressure control valve is controlled, the differential pressure is kept constant at A', that is, the pressure at the maximum rated combustion, 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 the variable throttle mechanism main body, 102 is the valve seat, 1
03 is a valve stem, and 104 is an O-ring. Valve stem 1
03, a gear A105, and a stepping motor 106 are coaxially connected. The potentiometer 108 is arranged to be rotationally driven from the gear A105 to the gear B107.

As is clear from FIG. 6, the stepping motor 106 is rotated in response to the temperature deviation signal 16, and therefore the valve seat 102 and the valve shaft 1 are rotated.
03, that is, the equivalent cross-sectional area of the flow path changes, and the gas fuel flow rate is controlled as described above.

As is clear from the above description, 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 outlet temperature, and the differential pressure between the upstream and downstream of the variable throttle mechanism is By detecting this with a pressure detector and using this pressure detection signal to control the gas pressure control valve, there is no need to control the pressure to a small value compared to the conventional fixed nozzle method, which reduces the This not only significantly improves the accuracy of gas fuel flow rate control, but also significantly reduces the ratio of the rated maximum combustion flow rate _qnax to the minimum combustion flow rate _qnio , the so-called TDR ( _qnio / _qnax ). . In other words, the combustion output adjustment range can be expanded to a greater extent than in the past.

[Brief explanation of the drawing]

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 5 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...Electric signal.

Claims (1)

[Claims] 1. A temperature sensor that detects the hot water temperature of the gas water heater, and a variable throttle mechanism that controls the amount of gas burned based on a temperature deviation signal from the temperature setting section, and a variable throttle mechanism that controls the amount of gas burned. A gas combustion proportional control device comprising: a gas pressure control valve which is provided with a pressure sensor for detecting a pressure difference between the pressure sensor and the downstream pressure sensor, and is controlled by an electric signal from the pressure sensor and is arranged in series with the variable throttle mechanism. 2. The gas combustion proportional control device according to claim 1, comprising: a gas pressure control valve that is controlled so that the differential pressure between the upstream and downstream sides of the variable throttle mechanism is approximately constant. 3. The gas combustion proportional control device according to claim 1, further comprising an adjusting operation section that simultaneously controls the amount of air required for combustion based on a temperature deviation signal that operates the variable throttle mechanism.