JP2939135B2 - Gas combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas combustion apparatus using city gas or LP gas as fuel, such as a gas water heater.

[0002]

2. Description of the Related Art Conventionally, in this type of gas combustion apparatus, a proportional valve provided in a gas supply path to a burner is energized and controlled by an energization amount corresponding to a required combustion amount of the burner, thereby obtaining the required combustion. It is generally known to generate a gas pressure corresponding to the amount on the inflow side of the nozzle of the burner (downstream of the proportional valve), thereby controlling the gas supply amount to the burner to an amount corresponding to the required combustion amount. ing. In this case, when energizing and controlling the proportional valve, the number of rotations of the combustion fan that supplies combustion air to the burner is controlled to a predetermined number of rotations in accordance with the required amount of combustion, and the number of rotations of the combustion fan is controlled. In some cases, the proportional valve is energized with an energizing amount corresponding to the above, so that the amount of gas supplied to the burner eventually becomes an amount corresponding to the required combustion amount.

[0003] Fuel gas used in this type of gas combustion apparatus is currently classified into 15 types of gas groups including LP gas in Japan, and each type of fuel gas is classified into its own gas. The calorific value, specific gravity, and burning rate index per unit volume are defined so as to fall within predetermined ranges. In the gas combustion apparatus using these types of fuel gas, the hole diameter of the nozzle of the burner or the like is set according to the gas group, so that combustion suitable for the gas group to be used is performed. ing.

[0004] Incidentally, the composition of the fuel gas of each type is not always the same depending on the gas company or region providing the fuel gas, even if the gas group is the same. Even within the group, the calorific value per unit volume of the fuel gas varies within a certain range.

However, in the conventional gas combustion apparatus, for example, when the required combustion amount is constant, basically, if the fuel gas is of the same gas group, a constant amount of fuel gas corresponding to the gas group is required. Since the fuel gas is supplied to the burner, the actual heat of combustion of the fuel gas in the burner (this corresponds to the product of the gas flow rate to the burner and the calorific value per unit volume of the fuel gas) is:
Variations occur due to differences in the calorific value of the fuel gas. Also, in the conventional gas supply device, the gas pressure on the inflow side of the nozzle of the burner is controlled to a constant value corresponding to the required combustion amount. When the fluctuation occurs due to the influence of clogging or the like, the flow rate of the gas ejected from the nozzle of the burner fluctuates accordingly, and the actual amount of combustion heat in the burner also fluctuates.

Therefore, in the conventional gas combustion device,
It has been difficult to accurately perform the combustion in the burner at the required combustion amount.

Further, even if the required combustion amount of the burner is fixed as described above, the actual combustion heat of the fuel gas in the burner varies with respect to the required combustion amount. In order to be able to combust, the range of the supply amount of combustion air is limited to a narrow range. However, when the combustion air is supplied from the combustion fan to the burner, the supply amount tends to fluctuate due to the influence of external wind, clogging of the exhaust port, and the like, and in such a case, the supply amount of the combustion air is reduced. The fuel does not match the actual heat of combustion of the fuel gas in the above, and poor combustion is likely to occur.

[0008]

SUMMARY OF THE INVENTION The present invention makes it possible to supply the burner with an amount of fuel gas corresponding to the required combustion amount of the burner by reducing the variation in the actual heat of combustion of the fuel gas in the burner. To provide a combustion device capable of ensuring good combustion of fuel gas in a wide range of a supply amount of combustion air when performing a burner combustion operation while supplying combustion air to a burner from a combustion fan. Aim.

[0009]

Means for Solving the Problems The present inventors have conducted various studies in view of the above background and found the following. That is, for example, by a thermal flow sensor or a hot wire flow sensor for detecting the flow rate or flow rate of gas,
When the gas flow to the burner is detected, the output level of the flow sensor changes basically according to the gas flow.

Further, as described above, when the gas flow rate of the fuel gas is detected by, for example, a thermal flow rate sensor or a hot wire flow rate sensor, when the output level of the flow rate sensor is observed with the gas flow rate kept constant, generally the same gas group Even if the fuel gas is a fuel gas having a gas composition that generates a large amount of heat per unit volume, the output level of the flow sensor becomes higher than that of a fuel gas that generates a small amount of heat. That is, the apparent gas flow rate grasped by the output level of the flow sensor increases as the calorific value per unit volume of the fuel gas increases. Specifically, for example, when using a thermal flow sensor using a platinum thin film resistor as a detection element as a flow sensor (an outline of this configuration will be described later) and measuring the output level of the flow sensor while keeping the gas flow constant,
The measurement data as shown in FIG. 7 was obtained. FIG. 7 shows a gas group of propane gas, a gas group of 6A, and 1 gas group.
A combination of the 3A gas group and the 12A gas group (13A and 12A can be combined as one gas group because the gas characteristics are similar)
The relationship between the calorific value of a plurality of types of fuel gas having different gas compositions in each gas group and the output level of the thermal type flow sensor at the constant gas flow rate (1 Nm ³ / h in FIG. 7) was shown. As can be seen from the drawing, even in the same gas group, the output level of the flow sensor increases as the calorific value of the fuel gas increases. Note that such characteristics are the same at other gas flow rates, and also when a hot-wire type flow sensor using a platinum wire or the like as a detection element is used as a gas flow sensor.

In order to achieve the above object, the present invention provides a gas flow control valve provided in a fuel gas supply path to a burner, and a gas flow control valve provided in the fuel gas supply path to provide a gas to the burner. A gas flow sensor that outputs a signal of a level corresponding to the flow rate and increases the output level as the calorific value of the fuel gas increases even if the gas flow rate is the same, and a required combustion of the burner during combustion of the burner. Target gas flow rate setting means for setting a target output level of the gas flow rate sensor corresponding to the amount as a target gas flow rate to the burner; and the gas flow rate control valve so that the output level of the gas flow rate sensor becomes the target output level. And valve control means for controlling the pressure.

The gas flow sensor is a thermal flow sensor or a hot wire flow sensor.

Further, a combustion fan for supplying combustion air to the burner, and a fan control for controlling the number of revolutions of the combustion fan so that an amount of combustion air corresponding to the required combustion amount is supplied to the burner. Means.

[0014]

According to the present invention, the gas flow rate to the burner is
The flow control valve is controlled by the valve control means so that a target output level of the gas flow sensor set by the target gas flow setting means corresponding to the required combustion amount matches an actual output level of the flow sensor. Is controlled via Therefore, for example, if the required combustion amount is constant, the gas flow rate to the burner is controlled to be constant. At this time, the output level of the gas flow rate sensor is required to be higher as the heating value of the fuel gas increases, even if the gas flow rate actually supplied to the burner is the same. If the combustion amount is constant (at this time, the output level of the gas flow rate sensor is controlled to a constant target output level), the gas flow rate actually supplied to the burner becomes larger as the calorific value of the fuel gas increases. , Become smaller. Accordingly, the actual heat of combustion of the fuel gas in the burner, that is, the product of the gas flow rate actually supplied to the burner and the calorific value per unit volume of the fuel gas is substantially the same regardless of the variation in the calorific value. And the variation of the actual amount of combustion heat is reduced. This makes it possible to accurately match the amount of combustion heat of the fuel gas supplied to the burner to the required amount of combustion.

This is because a thermal flow sensor or a hot wire flow sensor is adopted as the gas flow sensor, and the gas flow sensor has a characteristic that the output level increases as the amount of heat generated by the fuel gas increases. , The above control can be performed.

Further, as described above, since the actual amount of combustion heat of the fuel gas in the burner and the required amount of combustion match precisely, the combustion fan controlled by the fan control means in accordance with the required amount of combustion is provided. When the combustion air is supplied to the burner from, even if the supply amount of the combustion air fluctuates slightly due to the influence of the outside wind, etc., the supply amount of the combustion air is changed to the actual amount of the fuel gas in the burner. It becomes suitable for the amount of combustion heat, so that the burner can be satisfactorily burned with the required amount of combustion.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One example of the present invention will be described with reference to FIGS. 1 is a system configuration diagram of a gas water heater that is a gas combustion device of the present embodiment, FIG. 2 is a block configuration diagram of a main part of the gas water heater of FIG. 1, and FIG. 3 is a gas used in the gas water heater of FIG. FIG. 4 is an explanatory diagram for explaining the configuration of the flow sensor, and FIG.
Showing the output characteristics of the gas flow sensor of FIGS.
FIG. 2 is a diagram for explaining the operation of the gas water heater of FIG. 1.

Referring to FIG. 1, reference numeral 1 denotes a water heater main body containing a heat exchanger 2 and a burner 3 for heating the same, 4 denotes a water pipe installed through the heat exchanger 2, and 5 denotes a water pipe 4. Flow rate sensors for detecting the flow rate of water flowing through the heat exchanger 2 on the upstream side of the heat exchanger 2, and the flow rate sensors 6 and 7 detect the temperature of incoming water and the temperature of hot water flowing through the water flow pipe 3 on the upstream and downstream sides of the heat exchanger 2, respectively. A gas supply pipe (gas supply path) for supplying a fuel gas to the burner 3; a gas flow sensor 9 provided on the gas supply pipe 8 for detecting a gas flow supplied to the burner 3; , 11 are a gas flow control valve and an opening / closing solenoid valve provided in the gas supply pipe 8, respectively, 12 is a combustion fan for supplying combustion air to the burner 3, 13 is a fan motor for driving the combustion fan 12, and 14 is a combustion fan. Rotational speed sensor to detect 12 rotational speeds , 15 is an operation unit for the user to set tapping temperature, etc., 16 is a controller for controlling the operation of the fan motor 13, the gas flow control valve 10, the opening / closing solenoid valve 11, etc., and 17 is for igniting the burner 3. Igniter,
Reference numeral 18 denotes a frame rod for detecting a combustion state such as the presence or absence of misfire of the burner 3.

In this case, the burner 3 and the heat exchanger 2 are accommodated in a combustion chamber 19 formed in the water heater main body 1, and the combustion chamber 19 has an exhaust port 20 provided in an upper part of the water heater main body 1. Are in communication.

The upstream side of the water pipe 4 is connected to a water pipe (not shown), and the downstream side is connected to a hot water tap (not shown) in a kitchen or a bathroom.

The gas flow control valve 10 is, for example, a governor-equipped proportional valve that generates a gas pressure (secondary pressure) downstream of the gas flow control valve.

The fuel gas used in the gas water heater of this embodiment is, for example, a gas group of 12A and 13A.

The gas flow sensor 9 is, for example, a thermal flow sensor, and its general configuration is, as shown in FIG. 3, composed of three thin film resistance elements 21a to 21c made of platinum, for example.
And a sensor circuit section 22 for supplying an electric current to these thin-film resistance elements 21a to 21c to generate an output signal.
The thin film resistance elements 21a to 21c are arranged in the gas supply pipe 8 at regular intervals from the upstream side to the downstream side as shown in the figure. In this gas flow sensor 9,
The central thin-film resistance element 21b functions as a heater, and is supplied with a constant current or constant power from the sensor circuit unit 22, generates heat, and heats the thin-film resistance elements 21a and 21c on both sides thereof. The thin film resistance elements 21a and 21c on both sides are
It functions as a temperature sensor that generates a resistance value change depending on the temperature. When a fuel gas flows through the gas supply pipe 8, a temperature difference corresponding to the flow rate of the fuel gas is generated at the positions of the thin film resistance elements 21a and 21c. The resistance value changes according to the flow velocity. The sensor circuit section 22 includes the thin film resistance element 2
The change in the resistance value corresponding to the flow rate of the fuel gas 1a, 21c is converted into an electric signal, and a signal of a level corresponding to the flow rate is output to the controller 16. In this case, since the gas flow rate of the fuel gas flowing through the gas supply pipe 8 is obtained by multiplying the flow velocity by the cross-sectional area of the gas supply pipe 8, the gas flow rate is proportional to the flow rate of the fuel gas. The output signal level corresponds to the gas flow rate to the burner 3.

In this embodiment, the thin film resistance elements 21a to 21a
Although the thermal type flow sensor using 21c is employed as the gas flow sensor 9, for example, a hot wire type flow sensor using a platinum wire or the like may be used instead of the thin film resistance elements 21a to 21c.

In the gas flow sensor 9, the output characteristics as shown in FIG. 4 are obtained for the fuel gas of the group including the gas groups of 12A and 13A used in the present embodiment. The output level increases as the flow rate increases. Here, three characteristic lines are shown in FIG. 4, but they are fuel gas (13A-1, 13A-3, 12A-) having different compositions from each other.
3 shows an example of the output characteristics of the fuel gas of the type indicated by No. 3). Table 1 shows characteristics of the three types of fuel gas, such as specific gravity and calorific value.

[0026]

[Table 1]

As apparent from FIG. 4 and Table 1,
The fuel gas having a larger calorific value per unit volume has a larger slope of the characteristic line, and the output level of the gas flow sensor 9 at the same gas flow rate increases. In other words, this means that the gas flow rate at which the output level of the gas flow rate sensor 9 becomes a constant value decreases as the calorific value of the fuel gas increases.

Referring to FIG. 2, the controller 16 is constituted by an electronic circuit including a microcomputer and the like.
5 based on the set temperature given by the temperature sensor 5, the incoming water temperature and the hot water temperature detected by the temperature sensors 6 and 7, the water flow rate detected by the water flow rate sensor 5, and the like. A required combustion amount calculation unit 23 for obtaining the required combustion amount of the burner 3 from time to time, and a target rotation speed of the combustion fan 12 for obtaining a supply amount of combustion air corresponding to the required combustion amount calculated by the calculation unit 23 are set. The target rotation speed setting unit 24 to be set and the rotation speed of the combustion fan 12 are adjusted so that the rotation speed of the combustion fan 12 detected by the rotation speed sensor 14 matches the target rotation speed set by the target rotation speed setting unit 24. A fan control unit (fan control means) 25 which controls the fan through the fan motor 13 and a target gas flow rate to the burner 3 according to the rotation speed of the combustion fan 12 detected by the rotation speed sensor 14. A target gas flow rate setting unit (target gas flow rate setting means) 26 for setting a target output level of the corresponding gas flow rate sensor 9, and an output level of the gas flow rate sensor 9 matches a target output level set by the target gas flow rate setting unit. And a valve control unit (valve control means) 27 for controlling the amount of electricity supplied to the gas flow control valve 10.

Next, the operation of the gas water heater of this embodiment will be described.

When the flow of water through the water pipe 4 is started, the controller 16 detects this through the water flow rate sensor 5 and in response to the detection, the fan control unit 25 controls the fan motor 1.
At the same time, the combustion fan 12 is driven to rotate through the solenoid valve 3 and the solenoid valve 11 is opened to start supplying gas to the burner 3. Then, in this state, the burner 3 is ignited via the igniter 17, whereby the combustion operation (hot water supply operation) of the burner 3 is performed.
To start.

When the combustion operation of the burner 3 is started in this way, the controller 16 causes the required combustion amount calculating section 23 to output the hot water temperature detected by the temperature sensor 7 to the operating section 1.
The required combustion amount of the burner 3 required to match the set temperature set by the temperature sensor 5 is sometimes determined based on the input water temperature, the output water temperature obtained by the temperature sensors 6, 7 and the flow rate sensor 5, the detection data of the flow rate, and the like. Ask every moment. Then, the target rotation speed setting unit 24 of the controller 16 includes the required combustion amount calculation unit 23
The target number of revolutions of the combustion fan 12 for supplying the burner 3 with an amount of combustion air matching the required combustion amount obtained by the above is set according to a predetermined data table as shown by a solid line a in FIG. In FIG. 5, the hatched portion indicates the burner 3 when the combustion heat amount of the fuel gas actually supplied to the burner 3 matches the required combustion amount.
This indicates the range of the supply amount of combustion air that can perform good combustion. When the supply amount of the combustion air exceeds the above range at an arbitrary required combustion amount (combustion heat amount of fuel gas). In this case, a flame lift or the like in the burner 3 occurs, and when the temperature falls below the above range, incomplete combustion occurs.

When the target rotation speed of the combustion fan 12 is set by the target rotation speed setting unit 24 as described above, the fan control unit 25 sets the rotation speed of the combustion fan 12 detected by the rotation speed sensor 14 to the target rotation speed. The number of revolutions of the combustion fan 12 is controlled via the fan motor 13 so as to match the number. Thereby, the supply amount of the combustion air to the burner 3 becomes
The burner 3 is controlled to match the required combustion amount.

On the other hand, in parallel with this operation, the target gas flow rate setting unit 26 of the controller 16
The target output level of the gas flow sensor 9 corresponding to the target gas flow rate of the fuel gas to be supplied to the burner 3 in accordance with a predetermined data table as shown in FIG. Set. In this case, the number of revolutions of the combustion fan 12 is controlled to the target number of revolutions corresponding to the required amount of combustion. As a result, the target output level of the gas flow sensor 9 corresponding to the required amount of combustion is set. The Rukoto. The data table shown in FIG. 6 is defined corresponding to the group of the gas group of 13A and the gas group of 12A used in the present embodiment.
As long as the fuel gas is used, the same data table is used even if the composition of the fuel gas is different.

The target output level set as described above is given to the valve control unit 27. At this time, the valve control unit 27
Controls the amount of electricity supplied to the gas flow control valve 10 so that the actual output level of the gas flow sensor 9 matches the target output level.

More specifically, when the output level of the gas flow rate sensor 9 is smaller than the target output level, the amount of energization to the gas flow rate control valve 10 is increased to increase its opening degree.
The gas flow to burner 3 is increased. Conversely, when the output level of the gas flow sensor 9 is higher than the target output level, the amount of electricity supplied to the gas flow control valve 10 is reduced to reduce its opening, and the gas flow to the burner 3 is reduced. .
As a result, the gas flow rate to the burner 3 is controlled so that the output level of the gas flow rate sensor 9 matches the target output level.

In this case, as shown in FIG. 4, the 13A gas group or 12A gas group used in this embodiment is used.
The output characteristics of the gas flow sensor 9 differ depending on the magnitude of the calorific value of the fuel gas based on the difference in the gas composition, and the actual gas flow rate for the same target output level of the gas flow sensor 9 Varies depending on the magnitude of the calorific value of the fuel gas. For example, a gas group of 13A and a gas group of 12A showing output characteristics of the gas flow sensor 9 in FIG.
Assuming that the target output level of the gas flow sensor 9 is, for example, an output level of 6 m / s in terms of flow velocity, for the three types of fuel gas in the group including the above gas groups, the gas flow rate corresponding to the target output level is As shown in the drawing, a variation occurs between the flow rate ranges X. Then, at this time, as is apparent with reference to the figure, the gas flow rate decreases as the calorific value of the fuel gas increases, which is the same at any target output level.

Therefore, the amount of heat of combustion of the fuel gas actually supplied to the burner 3 corresponding to an arbitrary target output level determined according to the required combustion amount of the burner 3, that is, per unit volume of the fuel gas The product of the calorific value and the gas flow rate has substantially the same value regardless of the magnitude of the calorific value based on the difference in the composition of the combustion gas.

Actually, for example, the fuel gas (13A-) in which the slope of the output characteristic line of the gas flow sensor 9 shown in FIG.
1) and the fuel gas (12A-3) in which the slope of the output characteristic line becomes the smallest have a calorific value per unit volume of 11720 kcal / N as shown in Table 1.
m ³ , 8700 kcal / Nm ³ , and for these fuel gases, the target output level was converted to a flow velocity conversion value of 6 m / s.
In this case, the gas flow rates are 1.84 Nm ³ / h,
2.39 Nm ³ / h. Therefore, the combustion heat of the fuel gas supplied to the burner 3 at this time is about 2156, respectively.
0 kcal / h and 20790 kcal / h, which are almost the same value, and their difference (about 770 kcal / h)
h) is less than about 4% of the heat of combustion.

On the other hand, in the conventional gas water heater, basically, if the required combustion amount is constant, the fuel gas is supplied to the burner at the same gas flow rate regardless of the difference in the calorific value of the fuel gas. Since the fuel gas is supplied, the calorific value of the fuel gas supplied to the burner has a relatively large variation proportional to the difference between the calorific values due to the difference in the calorific value of the fuel gas. In fact, in a conventional gas water heater in which the proportional valve is energized and controlled with a constant energizing amount corresponding to the required combustion amount, as shown in Table 1, when the proportional valve current is fixed, the gas is actually supplied to the burner. The heat of combustion of the fuel gas is 13A-1, 13A-3, 12A-
A relatively large variation (4010 kcal / h in Table 1) occurs for fuel gas No. 3.

Further, in the gas water heater of this embodiment,
Since the gas flow rate is controlled so that the output level of the gas flow sensor 9 matches the target output level, even if the pressure in the combustion chamber 19 fluctuates due to the outside air, the clogging of the exhaust port 20, or the like, the necessary combustion is performed. As long as the target output level corresponding to the amount is constant, the gas flow is controlled to a constant gas flow corresponding to the target output level. Therefore, the amount of combustion heat of the fuel gas supplied to the burner 3 does not fluctuate due to the fluctuation of the atmospheric pressure in the combustion chamber 19.

As described above, in the gas water heater of the present embodiment, the combustion heat quantity of the fuel gas actually supplied to the burner 3 corresponding to an arbitrary target output level determined according to the required combustion quantity of the burner 3 Irrespective of the magnitude of the calorific value based on the difference in the composition of the combustion gas, and substantially the same value irrespective of the fluctuation of the atmospheric pressure in the combustion chamber 19, the gas flow rate sensor 9 according to the required combustion amount By appropriately setting the target output level, the amount of combustion heat accurately matches the required amount of combustion. Therefore, the fuel gas can be reliably supplied to the burner 3 with the amount of combustion heat corresponding to the required amount of combustion.
By burning the fuel gas, the burner 3 can be reliably burned with a required amount of combustion.

Further, as described above, the fuel gas can be supplied to the burner 3 with the amount of combustion heat corresponding to the required amount of combustion, and the combustion air to the burner 3 is basically supplied as described above. Is supplied in accordance with the data table indicated by the solid line a in FIG. 5, even if the supply amount of the combustion air slightly fluctuates due to the influence of the outside air or the clogging of the exhaust port 20, etc. It can be carried out.

That is, referring to FIG. 5, assuming that the required combustion amount is H ₀ , in the gas water heater of the present embodiment, the combustion heat amount of the fuel gas actually supplied to burner 3 is the fuel heat amount. The range in which the variation occurs due to the difference in the calorific value of the gas or the like is, for example, a narrow range as shown in FIG.
And in this case, regardless of the variation in the amount of combustion heat,
In order to satisfactorily burn the fuel gas, the supply amount of the combustion air only needs to be within a relatively wide range shown by ΔA in FIG. Therefore, even if the supply amount of the combustion air slightly fluctuates due to the influence of the outside wind, the clogging of the exhaust port 20, and the like, it is possible to secure a favorable combustion state of the burner 3.

On the other hand, in the conventional gas water heater, the variation range of the combustion heat amount of the fuel gas actually supplied to the burner for the same required combustion amount H ₀ is, for example, as shown by Δh in FIG. A relatively wide range. For this reason, in order to perform the fuel gas combustion satisfactorily regardless of this variation, the supply amount of the combustion air must be within a relatively narrow range shown in FIG.
Above or below a, poor combustion such as flame lift or incomplete combustion occurs. Therefore, even if the supply amount of the combustion air slightly fluctuates due to the influence of the outside air, clogging of the exhaust port, and the like, poor combustion is likely to occur.

In the gas water heater of the present embodiment, when the flow of water through the water pipe 4 is completed, the controller 16 detects this through the water flow rate sensor 5, and in response to the detection, turns the solenoid valve 11 on. The valve is closed to shut off the gas supply to the burner 3, and the fan control section 25 stops the combustion fan 12, thereby stopping the combustion operation of the burner 3. Such a stop operation of the combustion operation is similarly performed when the burnout of the burner 3 is detected by the frame rod 18 during the hot water supply operation.

As described above, in the gas water heater of the present embodiment, the amount of heat of combustion of the fuel gas supplied to the burner 3 is required with high accuracy regardless of the difference in the amount of heat generated due to the difference in the composition of the fuel gas. The fuel gas can be supplied to the burner 3 in accordance with the combustion amount, and the combustion of the burner 3 can be reliably performed with a desired combustion amount. Further, since the amount of combustion heat of the fuel gas supplied to the burner 3 can be made highly accurate, even if the supply amount of the combustion air fluctuates slightly due to the influence of outside wind, clogging of the exhaust port 20, and the like, A favorable combustion state of the burner 3 can be reliably ensured.

In the embodiment described above, 13
Although the gas water heater using the gas types A and 12A has been described, it goes without saying that a gas water heater using another gas type such as 6A or propane can be similarly configured as in the present embodiment.

In this embodiment, a gas water heater has been described as an example of a gas combustion device. However, it goes without saying that the present invention can be applied to other gas combustion devices such as a gas fan heater.

In this embodiment, a proportional valve with a governor is used as the gas flow control valve 10, but basically any other type of valve can be used as long as it can electrically control the gas flow. It is also possible to use.

Further, in this embodiment, the combustion fan 1 is controlled to a target rotation speed corresponding to the required combustion amount of the burner 3.
Although the target output level of the gas flow sensor 9 is set according to the number of rotations of 2, the target output level of the gas flow sensor 9 may be set directly according to the required combustion amount.

In the present embodiment, the target rotation speed of the combustion fan 12 is set according to the required combustion amount of the burner 3, and the rotation speed of the combustion fan 12 is controlled to reach the target rotation speed. For example, the amount of combustion air supplied to the burner 3 is detected by the air flow sensor, and the target air flow to the burner 3 is set according to the required combustion amount. The combustion fan is controlled so that the air flow detected by the air flow sensor matches the target air flow. Twelve rotation speeds may be controlled.

[0052]

As is apparent from the above description, according to the present invention, a signal of a level corresponding to the gas flow rate to the burner, such as a thermal flow rate sensor or a hot wire flow rate sensor, is output and the gas flow rate is reduced. Even if the amount of heat generated by the fuel gas is the same, a gas flow sensor whose output level increases as the calorific value of the fuel gas increases is provided in the gas supply path to the burner. By controlling the gas flow control valve provided in the gas supply path so that the target output level set correspondingly,
At least as long as the gas type is the same, it is possible to supply the burner with an amount of fuel gas corresponding to the required combustion amount of the burner with a small variation in the actual heat of combustion of the fuel gas in the burner, and it is possible to reliably obtain the burner. Can be burned with the amount of combustion.

When the combustion fan is supplied with the amount of combustion air corresponding to the required combustion amount from the combustion fan, the variation in the actual combustion heat of the fuel gas in the burner with respect to the required combustion amount is reduced as described above. By doing so, even if the supply amount of combustion air fluctuates somewhat due to the influence of outside air, clogging of the exhaust port, etc., it is possible to satisfactorily burn the fuel gas in the burner, and the supply amount of combustion air is wide. Good combustion of fuel gas can be ensured within the range.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a gas combustion apparatus (gas water heater) according to an example of the present invention.

FIG. 2 is a block diagram of a main part of the gas water heater of FIG. 1;

FIG. 3 is an explanatory diagram for describing a configuration of a gas flow sensor used in the gas water heater of FIG. 1;

FIG. 4 is a diagram showing output characteristics of the gas flow sensor of FIG. 3;

FIG. 5 is a diagram for explaining the operation of the gas water heater of FIG. 1;

FIG. 6 is a diagram for explaining the operation of the gas water heater of FIG. 1;

FIG. 7 is an explanatory diagram showing characteristics of a gas flow sensor used in the gas water heater of FIG. 1;

[Explanation of symbols]

3 burner, 8 fuel gas supply path, 9 gas flow sensor, 10 gas flow control valve, 12 combustion fan, 25
Fan control unit (fan control means), 26 target gas flow rate setting unit (target gas flow rate setting means), 27 valve control unit (valve control means).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23N 5/00 F23N 5/18

Claims (3)

(57) [Claims] A gas flow control valve provided in a supply path of fuel gas to a burner; and a gas flow control valve provided in a supply path of the fuel gas;
A gas flow sensor that outputs a signal of a level corresponding to the gas flow rate to the burner and, even when the gas flow rate is the same, as the calorific value of the fuel gas increases, the output level increases, and when the burner burns, Target gas flow rate setting means for setting a target output level of the gas flow rate sensor corresponding to the required combustion amount of the burner as a target gas flow rate to the burner; and an output level of the gas flow rate sensor being the target output level. A gas control device for controlling the gas flow control valve. 2. The gas combustion apparatus according to claim 1, wherein the gas flow sensor is a thermal flow sensor or a hot wire flow sensor. 3. A combustion fan for supplying combustion air to the burner, and a fan control for controlling the number of revolutions of the combustion fan so that combustion air in an amount corresponding to the required combustion amount is supplied to the burner. The gas combustion apparatus according to claim 1 or 2, further comprising: