JPH0625606B2 - Combustion control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a combustion control device which is used in a water heater, a heater, etc., and which adjusts the amount of fuel gas supplied by a governor proportional valve, in particular, two or The present invention relates to a burner equipped with two burners (hereinafter simply referred to as "two") and the number of burners used is switched.

[Prior Art] In combustion equipment such as a water heater, depending on the set combustion amount,
A combustion device equipped with two burners is used in order to secure a large calorific value as well as a small calorific value. In the case of a small calorific value, one or one unit (hereinafter simply referred to as "one") is used. The number of burners to be used is switched according to the required combustion amount, such as using two burners in the case of a large heat generation amount.

The pressure of the fuel gas applied to the nozzle that ejects the fuel gas to the burner is adjusted by the governor proportional valve to adjust the fuel supply amount.

[Problems to be Solved by the Invention] However, in the governor proportional valve, the secondary pressure changes depending on the amount of fuel gas passing through even if the same current value is applied, and particularly in the case of fuel gas with a small calorific value. In order to be able to supply a large amount of fuel gas corresponding to a large combustion amount, the nozzle diameter has been set large, and the energizing current value of the governor proportional valve has also been set large over the entire combustion amount. However, the amount of fuel gas passing through the governor proportional valve is large. Therefore, for example, the solenoid valve provided in the gas passage leading to one of the nozzles was closed while the minimum current value when two burners were used was passed, and the number of burners used was reduced to one. Only by increasing the pressure of the fuel gas applied to the nozzle corresponding to the burner used, it is not possible to sufficiently suppress the fuel gas amount by the nozzle, so even though the number of burners used is reduced, the supply of fuel gas is reduced. The quantity cannot be reduced sufficiently. On the contrary, when the governor proportional valve is energized with the maximum current value when two burners are used as the maximum current value when one burner is used, the fuel gas is similarly suppressed by the nozzle of the burner used. Is insufficient, the supply amount of the fuel gas cannot be sufficiently reduced as compared with the case where two burners are used, although the number of burners used is reduced.

Therefore, with such a fuel gas with a small heating value, as long as the current value of the governor proportional valve is the same, simply opening and closing the solenoid valve provided in the branch gas passage to each burner and switching the number of burners to be used However, there is a problem that the fuel supply amount cannot be set in a wide range.

The present invention, in particular, in a combustion control device that burns a fuel gas having a small calorific value by using two burners, automatically switches the number of burners to be used, and a wide range of combustion from a small burning amount to a large burning amount. An object of the present invention is to provide a combustion control device capable of reliably obtaining the amount.

[Means for Solving the Problems] In the present invention, two gas passages having two burners and nozzles for ejecting fuel corresponding to the two burners at the downstream ends are provided branching to the downstream side. A fuel gas supply passage, a governor proportional valve provided on the upstream side of the branch point of the fuel gas supply passage to the two gas passages, for adjusting the supply pressure of the fuel gas according to the energization current, and the fuel. An electromagnetic valve provided in one gas passage on the downstream side of the branch point of the gas supply passage for controlling the supply of fuel gas, a target fuel amount determining means for determining the target combustion amount of the two burners, and the target combustion According to the target combustion amount determined by the amount determining means, the energization current of the governor proportional valve and the opening / closing of the solenoid valve are controlled in association with each other, and the first of the governor proportional valves when the solenoid valve is in the closed state is controlled. The minimum current value at that time Is set to be smaller than the second minimum current value so that the supply pressure of the fuel gas is equal to the fuel gas supply pressure at the second minimum current value when the solenoid valve is in the open state, and the solenoid valve is in the open state. In the case of, the first maximum current value of the governor proportional valve is set to the second maximum value when the supply pressure of the fuel gas at that time is the second when the electromagnetic valve is in the closed state.
Is set to be larger than the second maximum current value so as to be equal to the supply pressure of the fuel gas at the maximum current value of, and the energization current value of the governor proportional valve is set to the first current value when the solenoid valve is in the closed state. Control is performed in a range between a minimum current value and the second maximum current value, and when the solenoid valve is in an open state, the energization current value of the governor proportional valve is set to the second minimum current value and the first minimum current value.
And a gas amount control means for controlling in a range between the maximum current value and the maximum current value.

[Operation] In the present invention, when the combustion amount set by the target combustion amount determining means is large, the solenoid valve is energized to be in the open state, and the fuel gas with a small calorific value whose pressure is adjusted by the governor proportional valve is It is ejected from two nozzles and supplied to each of the two burners.

When the set combustion amount is small, the solenoid valve is not energized and is in a closed state, and the fuel gas adjusted by the governor proportional valve is ejected only from the nozzle on the side where the solenoid valve is not installed to one of the burners. Supplied. The current flowing through the governor proportional valve at this time has a first minimum current value and a second maximum current value which are the same as those when the two burners are used together.
Are set to be smaller than the minimum current value and the first maximum current value, respectively, and are controlled in a current range smaller than that when two burners are used together.

EFFECTS OF THE INVENTION In the present invention, when the solenoid valve is closed and the number of nozzles is reduced, the minimum current value and the maximum current value of the governor proportional valve are smaller than those when the solenoid valve is open. It is set small and controlled within the range of the current value. Therefore, when the solenoid valve is closed, compared to when it is open,
The amount of fuel gas supplied is reduced overall.

In particular, the first minimum current value of the governor proportional valve when the solenoid valve is closed is applied to the nozzle when the pressure of the fuel gas applied to the nozzle is the second minimum current value when the solenoid valve is open. It is set to be equal to the pressure, and the first maximum current value of the governor proportional valve when the solenoid valve is in the open state is the second maximum when the pressure of the fuel gas applied to the nozzle is the second when the solenoid valve is in the closed state. Since the pressure is set to be equivalent to the pressure applied to the nozzle at the maximum current value of, the wide range from the upper limit to the lower limit of the good combustion range of each burner can be set when burning with two burners and by one burner. Both can be used to the maximum during combustion.

As a result, in the present invention, in the combustor using the fuel gas having a small calorific value, the solenoid valve is operated according to the target combustion amount under the condition that the nozzle pressure is higher in one burner than in two burners. By determining the opening and closing and the current value of the governor proportional valve, it is possible to change in a wider range from small combustion amount to large combustion amount while performing good combustion.
The combustion amount of the two burners can be quickly made the target combustion amount.

[Embodiment] Next, a combustion control device of the present invention will be described based on an embodiment shown in the drawings.

The gas-fired water heater 1 shown in FIG. 2 uses city gas, which has a small calorific value, as a fuel. A dual burner 11 for burning the fuel gas supplied by 20 is provided. Further, the combustor case 10 is provided with a combustion fan 12 that uses a brushless DC motor with a three-phase Y connection, and the dual burner 11 compulsorily blows air by the combustion air supplied by the combustion fan 12. The combustion exhaust gas after combustion is exhausted from the exhaust port 2 to the outside.

A heat exchanger 13 connected to a water supply pipe (not shown) is provided above the inside of the combustor case 10, and the water passing through the inside is heated by the heat generated by the combustion of the dual burner 11. In the vicinity of the dual burner 11 in the combustor case 10, a sparker 14 as an ignition device and a frame rod 15 as a flame detecting means are provided.

The gas supply pipe 20 is provided with a source solenoid valve 21 that allows the fuel gas to pass when energized from the upstream side, a main solenoid valve 22, and a governor proportional valve 23 that adjusts the supply amount of the fuel gas by controlling the supply pressure. At its downstream end, a double nozzle 16 for ejecting fuel to the double burner 11 is provided.

Further, in the present embodiment, in order to switch the number of burners to be used according to the usage state of the water heater, the gas supply pipe 20 for supplying the fuel gas to the first nozzle 16a, which is one of the double nozzles 16, has a A switching solenoid valve 24, which is the solenoid valve of the invention, is provided.

As shown in FIG. 1, the first nozzle 16a injects fuel to the first burner 11a which is one of the dual burners 11, and to the second burner 11b which is the other of the dual burner 11. A second nozzle 16b is provided for ejecting. When the switching solenoid valve 24 is closed, the second
When the burner 11b only burns and is open, the first
The burner 11a and the second burner 11b both burn. At this time, the governor proportional valve 23 adjusts the supply pressure to each downstream nozzle in each state according to the energized current.

An outlet hot water temperature thermistor 25 that detects the temperature of the heated water is provided downstream of the heat exchanger 13.

The control device 30 is the combustion amount setting means and control means of the present invention, and as shown in FIG. 3, is composed of the following circuits centering on the microcomputer 40.

The sparker circuit 31 is a circuit for energizing a high voltage generation circuit for generating spark discharge in the discharge gap of the sparker 14 via a relay.

The fan circuit 32 drives the brushless DC motor of the combustion fan 12 according to the set combustion amount, and detects the rotation speed of the combustion fan 12.

The proportional valve circuit 33 energizes the governor proportional valve 23 so that the amount of fuel gas supplied to the dual burner 11 and the combustion air supplied by the combustion fan 12 have an appropriate air-fuel ratio. And is energized based on the number of rotations detected by the fan circuit 32.

Further, in this embodiment, the switching solenoid valve 24 is closed to stop the use of the first burner 11a, which is one of the dual burners 11, and the governor proportional valve when only the second burner 11b is used.
The minimum current value and the maximum current value of the energizing current of 23 are set to the first burner 11a and the second burner 11 by opening the switching solenoid valve 24.
It is set to be smaller than the minimum current value and the maximum current value when both are used. This is because, in this embodiment, the city gas having a small calorific value is used as the fuel gas, and the amount of gas passing through each nozzle and the governor proportional valve 23 is relatively large. That is, in FIG. 4, the solid line A shows the relationship between the energizing current to the governor proportional valve 23 and the nozzle pressure when both the first burner 11a and the second burner 11b are used, and when only the second burner 11b is used. The relationship between the energizing current to the governor proportional valve 23 and the nozzle pressure is shown by a broken line B, and in FIG. 5, the solid line C shows the change in the fuel gas supply amount when both the first burner 11a and the second burner 11b are used. Then, a change in the supply amount of the fuel gas when only the second burner 11b is used is indicated by a broken line D, and the supply amount of the fuel gas from one burner when both the first burner 11a and the second burner 11b are used. When each of the changes is indicated by a broken line E, the nozzle pressure of each nozzle is indicated by P ₁ by the minimum current value iA when both the first burner 11a and the second burner 11b are used. When the minimum current value iA at this time is energized when only the second burner 11b is used as it is, the nozzle pressure of the second nozzle 16b is indicated by P ₂ .

The supply amount of the fuel gas supplied from the second nozzle 16b to the second burner 11b by the minimum current value iA is, as shown in FIG. 5, the supply amount Q ₂ , when two burners are used,
When only the second burner 11b is used, it is indicated by the supply amount Q ₁ . As is clear here, this supply amount Q ₁
Is almost the same as the total supply amount Q ₂ supplied from the two nozzles when two burners are used, and there is no point in providing the switching solenoid valve 24 as it is.

Therefore, in this embodiment, when the switching solenoid valve 24 is closed, the minimum current value iB is set as the minimum current value when the fuel gas is supplied only from the second nozzle 16b, as shown in FIG. There is. As a result, the nozzle pressure can be set to P ₁ even when only the second burner 11b is used, and Q ₀ can be set to the minimum supply amount as the supply amount according to this pressure.

Also, when using two burners, the maximum current value IA
When the current is energized, the nozzle pressure is indicated by P ₃ , and when this current value is energized when one burner is used, the nozzle pressure is indicated by P ₄ . The amount of fuel gas supplied to the Ai 2 burner 11b by this nozzle pressure P ₄ becomes Q ₃ as shown in FIG. 5, which is compared with the amount of fuel gas Q ₄ supplied when two burners are used. Not a few. Therefore, in the present embodiment, the maximum current value IB of the governor proportional valve 23 when only the second burner 11b is used is set smaller than the maximum current value IA when two burners are used, and the maximum supply amount of fuel gas is set. is it holding in _{Q 5.}

As described above, in the combustion device using the city gas having a small calorific value as in the present embodiment, the current value of the governor proportional valve 23 when the switching solenoid valve 24 is switched and only the second burner 11b is used is the minimum. Since the current value iB changes in the range from the maximum current value IB, the supply amount of the fuel gas can be changed from Q ₀ to Q ₅ , and in particular, the minimum supply amount of the fuel gas can be reliably set small. .

The water amount detection circuit 34 detects the inflowing water amount by detecting the rotational speed of the impeller of a water amount sensor provided in a water supply pipe (not shown) upstream of the heat exchanger 13.

The water valve circuit 35 is a circuit for driving a gad motor of a water amount control valve (not shown) provided in the water supply pipe upstream of the water amount sensor, and the water amount control valve is provided with a potentiometer for detecting its opening. However, the water amount control valve is controlled to an appropriate opening degree according to the control state based on the detection signal from the potentiometer.

The water temperature detection circuit 36 detects the temperature of the water heated by the heat exchanger 13 from the signal from the hot water temperature thermistor 25 and the signal from an incoming water temperature thermistor (not shown) provided upstream of the heat exchanger 13. It is a circuit for detecting the temperature of water flowing into the heat exchanger 13, respectively.

The control circuit 37 is an operation unit for operating the operating state of the gas combustion type water heater 1, and includes an operation switch and a temperature setting switch. This control circuit 37
It is connected by a wire-saving two-wire wiring (not shown) so that it can be operated remotely, and it is operated by electric power supplied from this two-wire wiring. Then, the operation signal and the temperature setting signal are digitally generated, modulated into a predetermined carrier wave, and transmitted.

The interface circuit 38 consists of the above circuits, the original solenoid valve 2
1, main solenoid valve 22, switching solenoid valve 24 and frame rod 1
5 is a circuit for transmitting a signal between the CPU 40 and a later-described CPU 40, especially when the flame of the dual burner 11 is no longer detected in the energizing circuit for the source solenoid valve 21 and the main solenoid valve 22. A safety circuit 39 for stopping the fuel is provided.

The microcomputer 40 (hereinafter referred to as the CPU 40) comprehensively controls the operating states of the above circuits, includes a ROM 41 and a RAM 42 as storage devices, and is preset in the ROM 41 by an operation signal from the control circuit 37. The gas combustion type water heater 1 is operated in the following operation sequence,
Based on the setting state of the control circuit 37 and each signal from the water amount detection circuit 34 and the water temperature detection circuit 36, the dual burner 11
Calculate and set the amount of combustion required to set the amount of combustion of the fan circuit 32, proportional valve circuit 33 and switching solenoid valve 24
Are in control.

Further, in the present embodiment, the energization current control of the governor proportional valve 23 is performed, and when the switching solenoid valve 24 is energized and de-energized,
The range of the energizing current of the proportional valve circuit 33 is switched to reduce the current value in the non-energizing state.

Next, the gas combustion type water heater 1 of the present embodiment having the above configuration
The operation of will be described with reference to FIG.

When the user turns on the operation switch, the control device 30 is activated by the signal, and the operation is started in a predetermined sequence.

The controller 30 controls the combustion fan according to the set combustion amount.
Control 12 and governor proportional valve 23. The fuel gas whose supply pressure is adjusted by the governor proportional valve 23 is supplied to the first nozzle 16a.
And it is jetted from the second nozzle 16b to the first burner 11a and the second burner 11b, respectively. At this time, the amount of fuel gas ejected from each nozzle is an amount corresponding to the energizing current of the governor proportional valve 23, and the energizing is performed in different current value ranges depending on the open state and the closed state of the switching solenoid valve 24. ,
When the set combustion amount is small and combustion is performed only by the second burner 11b, even if the supply pressure of the fuel gas to the second nozzle 16b rises when the switching solenoid valve 24 is closed, Since it is set to be smaller than the minimum current value and the maximum current value of the energizing current of the governor proportional valve 23 when burning with a book burner, respectively, the pressure can be adjusted to a lower pressure, so that the supply amount of fuel gas can be reduced. .

The fuel gas supplied to each burner is mixed with the combustion air supplied by the combustion fan 12 and burned, so that the set combustion amount can be obtained.

As described above, in the present invention, even in the case of using a fuel gas having a small calorific value in a combustion device that uses two or two burners and closes one of them according to the usage state,
By closing the switching solenoid valve, the supply amount of fuel gas can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining the operation of this embodiment, and FIG.
FIG. 3 is a schematic configuration diagram showing a gas combustion type water heater of this embodiment, FIG. 3 is a block diagram showing a control device of this embodiment, and FIG. FIG. 5 is a characteristic diagram showing the relationship, and FIG. 5 is a characteristic diagram showing the relationship between the energizing current and the fuel gas supply amount of the governor proportional valve of the present embodiment. In the figure, 11a ... first burner, 11b ... second burner, 16a
...... First nozzle, 16b ...... Second nozzle, 23 ...... Governor proportional valve, 24 ...... Switching solenoid valve (solenoid valve), 30 ...... Control device (combustion amount setting means, control means).

Claims (1)

[Claims] 1. A fuel gas supply path provided with two burners and two gas passages each having a nozzle for jetting fuel corresponding to each of the two burners at a downstream end and branched to a downstream side, and the fuel gas supply passage. A governor proportional valve provided on the upstream side of the branch point of the gas supply path to the two gas passages, for adjusting the supply pressure of the fuel gas according to the energization current, and downstream of the branch point of the fuel gas supply path. A solenoid valve provided in one of the gas passages on one side for controlling the supply of fuel gas, a target fuel amount determining means for determining a target combustion amount of the two burners, and the target determined by the target combustion amount determining means. The current flowing through the governor proportional valve and the opening / closing of the solenoid valve are controlled in association with each other according to the amount of combustion, and the first minimum current value of the governor proportional valve when the solenoid valve is in the closed state is defined as the fuel at that time. Gas supply pressure is before The governor proportional valve is set to be smaller than the second minimum current value so as to be equal to the supply pressure of the fuel gas at the second minimum current value when the solenoid valve is open, and the solenoid valve is open. Of the second maximum current so that the supply pressure of the fuel gas at that time becomes equal to the supply pressure of the fuel gas at the second maximum current value when the solenoid valve is in the closed state. When the solenoid valve is set to a value larger than the above value, the energization current value of the governor proportional valve is controlled in the range between the first minimum current value and the second maximum current value, and Combustion control comprising gas amount control means for controlling the energization current value of the governor proportional valve in the range between the second minimum current value and the first maximum current value when the solenoid valve is in the open state. apparatus.