JPH023088B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention makes a gas combustor such as a gas water heater equipped with an electromagnetic proportional valve compatible with the gas type, and also makes it possible to switch the capacity of the combustor. It relates to a combustion control circuit.

(Prior Art) As a conventional combustion control circuit, a control circuit built into a board changes the current flowing through the coil of an electromagnetic proportional valve installed in a fuel supply path according to changes in load. It is known that the amount of combustion of a burner is controlled by changing the opening degree of a proportional valve.

(Problem to be Solved by the Invention) By the way, gas combustors with different capacities generally use dedicated burners with corresponding maximum rated combustion amounts, and the control circuit also corresponds to the dedicated burners. A dedicated circuit is used to do this, making it difficult to mass-produce. Further, even when the gas types are different, a dedicated circuit is used as the control circuit, which is bad for mass production.

(Means for Solving the Problems) An object of the present invention is to provide a combustion control circuit with excellent mass productivity. The amount of combustion of the burner is controlled by changing the opening degree of the proportional valve according to changes in load, and an adjustment circuit is provided to adjust the current of the coil in accordance with the type of gas. At the same time, a capacity switching circuit is provided to control the upper limit current value of the coil, and the capacity switching circuit can freely switch the upper limit current value in multiple stages of high and low levels within a range below the current value that supplies the maximum rated combustion amount of the burner. It is characterized by what it did.

(Function) The present invention has the above configuration, and according to this, when the types of gases supplied to the burner of the gas combustor are different, the current of the coil of the electromagnetic proportional valve is adjusted by the adjustment circuit to the gas type. It can be adjusted to correspond to the current value of the coil, and even when the capacity of the gas combustor is different, it can be applied by switching the upper limit current value of the coil using the capacity switching circuit.

(Example) Examples of the present invention will be described below based on the drawings.

Fig. 1 shows an embodiment in which the present invention is applied to a gas water heater. , 4 is a heat exchanger, 5 is a temperature sensing element consisting of a thermistor facing into the water supply pipe on the downstream side of the heat exchanger 4, and 6 is a temperature sensing element of the present invention that controls the current flowing through the coil of the proportional valve 2. The control circuits are shown respectively.

Next, the specific configuration of the control circuit 6 will be explained based on FIG. 2.

The illustrated example shows an example in which the magnitude of the load is taken as the deviation between the hot water outlet temperature and the set temperature, and is linked to a temperature sensing element 5 for detecting the hot water outlet temperature and a temperature control knob (not shown). A bridge circuit 8 incorporating a variable resistor 7 for setting the tapping temperature detects the deviation between the tapping temperature and the set temperature in the form of a potential difference between connection point A and connection point B, and detects the difference in potential, that is, the voltage. is operationally amplified by an operational amplifier 9, and further level-adjusted by a voltage dividing circuit 10.
The current is input to the base of the transistor 11, and a current corresponding to the difference between the tapped water temperature and the set temperature is generated on the collector side of the transistor 11. This current flowing to the collector side is passed through the coil 2a of the electromagnetic proportional valve 2 interposed in the gas supply path 3 to the burner 1 to change the opening degree of the proportional valve 2. The combustion amount of burner 1 is controlled proportionally up to the maximum rated combustion amount Q _M.

Note that 12 in FIG. 2 indicates an operational amplifier that compensates the current flowing through the coil 2a against disturbances.

Although the above configuration is not particularly different from the configuration of the conventional circuit, the present invention provides an adjustment circuit 19 that adjusts the current of the coil 2a of the electromagnetic proportional valve 2 provided in the gas supply path 3 in accordance with the type of gas. In addition to providing
A capacity switching circuit 13 is provided to control the upper limit current value of the coil 2a, and the capacity switching circuit 13 sets the upper limit current value in multiple stages of high and low levels within a range below a current value I _M that supplies the maximum rated combustion amount of the burner 1. It can be switched freely.

To explain in detail what is shown in the figure, an adjustment circuit 19 corresponding to the type of gas is incorporated on the non-grounded side of the voltage division point C of the voltage division circuit 10, and this adjustment circuit 19 has three mutually parallel resistors. 20, 21, 22, and one selector switch 23 for selecting these resistors 20, 21, 22, each resistor 20, 21, 22 can be used for city gas, natural gas, or propane gas. By switching 23, the dividing point C
The potential of is set to a value according to the gas type.

Further, a capability switching circuit 13 is incorporated on the ground side of the voltage dividing point C of the voltage dividing circuit 10, and this capability switching circuit 13 consists of three resistors 14, 15, and 1 connected in series with each other.
6 and two of them each parallel switch 17,
18, and by switching this capacity switching circuit 13, the potential at the voltage dividing point C can be freely switched between three high and low levels.

To explain this more specifically, both switches 1
If switches 7 and 18 are opened, resistor 14 and resistor 15 are short-circuited, and the potential at voltage dividing point C can be made the lowest. If only switch 17 is opened, resistor 1
4 is short-circuited, and the potential of voltage dividing point C is changed to both switches 1
By opening both switches 17 and 18, the potential at the voltage dividing point C can be made highest.

In this way, by switching the potential at the voltage dividing point C into three high and low levels, the maximum base potential of the transistor 11 can be changed into three levels, and as a result,
The upper limit current value of the coil 2a of the electromagnetic proportional valve 2 is set in three high and low levels within the range below the current value that supplies the maximum rated combustion amount Q _M of the burner 1. For example, I ₁ as shown in FIG. 3,
It can be switched to three stages: I ₂ and I _M.

Next, to explain its operation, a gas water heater to which city gas is supplied is operated by changing the electric potential at the partial pressure point C by switching the adjustment circuit 19 without changing the control circuit 6, and controlling the electromagnetic proportional valve 2. By simply changing the current in the coil 2a, the water heater can be changed to either a gas water heater supplied with natural gas or a gas water heater supplied with propane gas.

Also, for example, a No. 16 gas water heater can be converted into a No. 15 gas water heater or a No. 13 gas water heater by simply switching the capacity switching circuit 13 without changing the burner 1 or the control circuit 6. This can be changed, and if this is detailed,
If you want to use it as a No. 13 gas water heater, close both switches 17 and 18 of the capacity switching circuit 13, and set the upper limit current value of the coil 2a of the electromagnetic proportional valve 2 to the No. 16 gas water heater. The coil current value I _M that supplies the maximum rated combustion amount Q _M of the burner 1 of the burner 1 may be set to a value considerably lower than the value I _M shown in FIG. 3, for example.

According to this, the maximum opening degree of the electromagnetic proportional valve 2 is set to 16
The maximum rated opening of burner 1 can be made smaller than the maximum rated opening of the No. 2 gas water heater, and the maximum combustion amount of burner 1 can be set to Q ₁ , which is smaller than the maximum rated combustion amount Q _M.
A gas water heater with a capacity of 16 can be changed to a capacity of 13.

In addition, if you want to use it as a No. 16 gas water heater, both switches 17 and 18 of the capacity switching circuit 13
The upper limit current value of the coil 2a of the electromagnetic proportional valve 2 may be set to _IM as shown in the third figure.

Incidentally, in the above-mentioned embodiments, the case where the gas type is different and the case where the capacity is different have been explained separately, but it goes without saying that the present invention can also be applied to the case where the gas type and the capacity are different at the same time.

(Effects of the Invention) According to the present invention, an adjustment circuit is provided to adjust the current of the coil of the electromagnetic proportional valve interposed in the gas supply path in accordance with the type of gas, and the upper limit current value of the coil is provided. By using a capacity switching circuit, it is possible to freely switch between high and low levels in the range below the current value that supplies the burner's maximum rated combustion amount, so it can be used for both gas combustors that differ only in gas type and gas combustor that differ only in capacity. Adjustment of the adjustment circuit and/or switching of the capacity switching circuit can also be applied to gas combustors with different gas types and capacities. Compared to the conventional circuit, which requires the preparation of a dedicated control circuit corresponding to the above case, the present invention has an advantage in mass productivity.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a gas appliance to which the present invention is applied, Fig. 2 is a circuit diagram showing an example of the present invention, and Fig. 3 is a diagram showing the relationship between coil current value and combustion amount. . 2... Solenoid proportional valve, 2a... Coil, 3...
Gas supply path, 13...capacity switching circuit, 19...adjustment circuit.

Claims (1)

[Claims] 1 The current flowing through the coil of an electromagnetic proportional valve installed in the gas supply path is changed in accordance with changes in load, and the opening degree of the proportional valve is changed to control the combustion amount of the burner. , an adjustment circuit is provided to adjust the current of the coil according to the gas type, and a capacity switching circuit is provided to control the upper limit current value of the coil, and the capacity switching circuit supplies the maximum rated combustion amount of the burner. 1. A combustion control circuit characterized in that the upper limit current value can be freely switched between high and low levels within a range below the current value.