JPH0749849B2 - Combustion control device for water heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a combustion control device for a water heater, a bath heater, a hot water heater, and other water heaters.

(Prior Art) As a conventional device of this type, an electromagnetic safety valve and a water pressure responsive valve that opens by passing water to a heat exchanger heated by the burner are provided in a gas supply path to the burner. Connect the thermoelectric generator facing the burner to the coil of the electromagnetic safety valve,
It is known that the electromagnetic safety valve, which is opened in association with the ignition operation, is kept open by a predetermined electromotive force generated from the thermoelectric generator so that combustion of the burner is continued.

(Problems to be Solved by the Invention) However, generally, immediately after the combustion of the burner is stopped, the thermoelectric generator is heated by the remaining heat and continues to generate a predetermined electromotive force. The electromagnetic safety valve continues to be held in the open state. Therefore, if only water is used immediately after combustion of the burner is stopped, the hydraulically operated valve opens, which causes a disadvantage that raw gas is released.

(Means for Solving the Problems) The present invention is intended to provide a device for solving the above-mentioned inconvenience, and is provided in a gas supply path to a burner, an electromagnetic safety valve, and a heat exchanger heated by the burner. The electromagnetic safety valve opened by operating water is connected to the coil of the electromagnetic safety valve, and the electromagnetic safety valve opened in conjunction with the ignition operation is installed. In the case where the combustion of the burner is continued by maintaining the valve open state with a predetermined electromotive force generated from the thermoelectric generator, the coil of the electromagnetic safety valve is connected to the coil of the thermoelectric generator after the combustion of the burner is stopped. A reverse current generating means for flowing a reverse current until the electric power becomes less than a predetermined electromotive force is provided.

(Operation) According to the present invention, according to the above-mentioned configuration, when the ignition operation of the burner and the water passage operation of the heat exchanger are performed, the electromagnetic safety valve and the water pressure responsive valve are opened and the burner is protected from gas. When supplied, the ignition circuit is activated and the burner is ignited.
Then, when the burner is ignited, a predetermined electromotive force is generated from the thermoelectric generator, the electromagnetic safety valve is held in the open state by the predetermined electromotive force, and the burner continues to burn, and the burner burns the heat exchanger. When heated, hot water is obtained from the heat exchanger.

After that, when the burner extinguishing operation and the heat exchanger water stop operation are performed, the ignition circuit is deactivated, and the water pressure responsive valve is closed to stop the combustion of the burner. Immediately after combustion of the burner is stopped, the thermoelectric generator element is heated by the remaining heat and continues to generate a predetermined electromotive force.Therefore, in the conventional one in which current is passed to the coil only by this predetermined electromotive force, the electromagnetic safety valve is opened. The holding state continues, and at this time, since only the water is used, when the water exchange operation of the heat exchanger is performed again, the water pressure responsive valve opens, so raw gas is released, but in the present invention,
Immediately after combustion of the burner is stopped, a reverse current is supplied to the coil by the reverse current generating means so that the forward current flowing in the coil is set to the holding current or less and the electromagnetic safety valve can be closed, so that raw gas is released. Never.

(Example) Next, the Example of this invention is described based on drawing.

In FIG. 1, (1) shows a manual valve-opening type electromagnetic safety valve provided in a gas supply path (3) to a burner (2), and the electromagnetic safety valve (1) is a compound winding coil (4) with low power consumption. ), One of the coils (4a) is connected to a thermocouple (5) which is a thermoelectric generator heated by the burner (2), and the other coil (4b) is connected to a battery (6) which is a power source. It is configured to connect.

An ignition circuit (8), a first timer circuit (9), a flame detection circuit (10), and a safety valve drive circuit (11) are sequentially provided in a circuit (7) connecting the coil (4b) to a battery (6). I set it up.

The ignition circuit (8) includes a discharge circuit (14) including a capacitor (12) and a small resistance value (13), and a charging circuit (1) including the capacitor (12) and a large resistance value (15).
Incorporating a second timer circuit (17) with 6),
The power from the battery (6) is directly supplied to the oscillation circuit (19) by the hold switch (22) that is switched to the normally open side (NO side) when the burner (2) is ignited, and this is operated to ignite. A high voltage is generated on the secondary side of the transformer (20), the high voltage is applied to the ignition electrode (21) to generate a spark between the electrodes, and an ignition switch (1
The capacitor (12) is charged for a predetermined time by 8), and the oscillation circuit (19) is operated during this predetermined time to generate a spark between the electrodes as in the case of the hold switch (22). I decided.

The first timer circuit (9) is operated for a certain period of time until a predetermined electromotive force is generated from the thermocouple (5) in conjunction with the ignition operation, and a hold switch (which is switched during the ignition operation of the burner (2) ( The capacitor (23) (23) is charged for a certain period of time by the 22), and the transistor (24) (25) (26) is charged during this time.
The flame detection circuit (10) is brought into conduction, and the voltage of the battery (6) is applied to the flame detection circuit (10) at the subsequent stage for a certain period of time to bring the flame detection circuit (10) into a ready state for operation.

The flame detection circuit (10) is of a flame rod type, and the oscillation circuit (27) is activated by the operation of the first timer circuit (9), and the AC voltage from the oscillation circuit (27) is applied to the flame rod (28). ), And when the burner (2) is ignited, the transistor (19) is made non-conductive and the transistor (30) is made conductive by the rectified current flowing through the flame into the frame rod (28). Furthermore, by incorporating a third timer circuit (34) having a charging circuit (35) consisting of a small resistance resistor (31) and a small capacitance capacitor (32), flame fluctuation, oxygen concentration Even if a predetermined current does not flow through the frame rod (28) for a moment due to a decrease in the temperature of the transistor (29) and the transistor (29) becomes non-conducting, a charging current flows through the capacitor (32) for 0.8 seconds during that moment, and the transistor With a structure in which (30) is conductive It was.

The safety valve drive circuit (11) comprises a transistor (35), a current limiting resistor (36) and a coil (4b), and the transistor (29) of the flame detection circuit (10) is non-conductive and the transistor (30). When is on, the transistor (3
5) is conducted to apply the voltage of the battery (6) to the coil (4b).

Reference numeral (37) denotes a water pressure responsive valve provided on the downstream side of the electromagnetic safety valve (1) of the kazu supply path (3), and the water pressure responsive valve (37).
Is a water governor (4) provided in a water supply pipe (39) connected to the upstream end of a heat exchanger (38) heated by the burner (2).
The valve is configured to open in conjunction with the displacement of (0) during water flow.

In the figure, (41) is the gas governor, (42) is the ignition burner, and (4)
3) is a purge valve, (44) is a normal fire burner, and (45) is a pilot valve.

At this time, the electromagnetic safety valve (1), the pilot valve (45), the purge valve (43), and the water pressure responsive valve (37) are opened by the ignition operation and the water passage operation, and the burner (2) and the ignition burner ( 42), gas is supplied to the constant-fire burner (44),
The ignition switch (18) is closed, and the operation of the ignition circuit (8) is started for a predetermined time, and at the same time, the hold switch (2
2) is switched, the operation of the first timer circuit (9) is started for a fixed time, and the voltage of the battery (6) is changed to the transistor (26).
Is applied to the flame detection circuit (10) via
0) is ready for operation. In this case, the second timer circuit (17) continues sparking for a predetermined time even after the ignition operation is released.

If the ignition operation is a so-called cold start at the start of use of the combustor, the burner (2) is ignited by the spark of the ignition circuit (8) through the ignition burner (42) and the normal fire burner (44). When there is no momentary ignition, flame fluctuation, or decrease in oxygen concentration, a rectified current continuously flows through the frame rod (28), and the flame detection circuit (10) continuously operates to operate the battery (6). The voltage is supplied to the electromagnetic coil (1) coil (4b) through the transistor (35) which is a switch of the safety valve drive circuit (11), and the electromagnetic safety valve (1) opens the first timer circuit (9) for a certain period of time. State, then the electromagnetic safety valve (1) is heated by the burner (2) Thermocouple (5)
The coil (4a) is energized by a predetermined electromotive force from and the valve is kept open to continue the combustion of the burner (2).
As shown in Fig. 2 (a), the burner (2) was instantly ignited, but due to flame fluctuations, a decrease in oxygen concentration, etc., the specified rectified current did not flow to the frame rod (28) for a moment. ,
After that, when a predetermined rectified current begins to flow, the flame detection circuit (10) is forcibly activated by the third timer circuit (34) during that moment, as shown in FIG. The safety valve (1) is kept open as shown in Fig. 2 (g), and thereafter, the burner (2) is instantly ignited, and the same as when there is no flame fluctuation or decrease in oxygen concentration. The electromagnetic safety valve (1) is held in an open state by the operation of the flame detection circuit (10) and a predetermined electromotive force from the thermocouple (5),
Burning of the burner (2) is continued, and hot water is obtained from the tap pipe (46) connected to the downstream end of the heat exchanger (38). Even when the rectified current flowing through the frame rod (28) changes as shown by the dotted line in FIG. 2 (a), the third timer circuit (3
Of course, 4) can hold the electromagnetic safety valve (1) in the open state.

When the burner (2) sparks in the ignition circuit (8) and does not ignite instantly, no current flows in the flame rod (28), the flame detection circuit (10) becomes inoperative, and the battery (6) The voltage is not supplied to the coil (4b), the electromagnetic safety valve (1) is quickly closed, and the burner (2) is maintained in a stopped state.

If the above ignition operation involves extinguishing the burner (2) during use of the combustor and then immediately performing ignition operation during the burner (2), that is, during a so-called hot start.
Regardless of whether the timer circuit (9), the flame detection circuit (10), or the safety valve drive circuit (11) is operating, the remaining heat continues to generate a predetermined electromotive force from the thermocouple (5), which causes the coil ( When the burner (2) is instantly ignited by the spark of the ignition circuit (8), the combustion of the burner (2) is continued because the electromagnetic safety valve (1) is kept open. , Hot water can be obtained from the tap pipe (46).

When the burner (2) does not instantly ignite due to the spark of the ignition circuit (8), the operation of the second timer circuit (17) causes the operation of the ignition circuit (8) to continue for a predetermined time.
Within this predetermined time, the burner (2) is surely ignited, the combustion of the burner (2) is started, and hot water is obtained from the hot water discharge pipe (46).

Therefore, even when the ignition operation is carried out for a sufficient time, or even when it is carried out instantaneously, the release of the raw gas is not continued and it is safe.

After that, when the burner (2) is extinguished and the heat exchanger (38) is stopped, the hold switch (22) is switched to the normally closed side (NC side) and the ignition switch (18) is closed. Also, the ignition circuit (8) becomes inoperative, the water pressure responsive valve (37) closes, the combustion of the burner (2) is stopped, and the tap pipe (4)
Hot water from 6) is also stopped. Immediately after the combustion of the burner (2) is stopped, the thermocouple (5) is heated by the remaining heat and continues to generate the predetermined electromotive force. Therefore, as described in the section of the action, only the predetermined electromotive force is generated. In the conventional type in which a current is applied to the coil (4b), the electromagnetic safety valve (1) remains open, and when only the water is used at this time, the water pressure of the heat exchanger (38) is changed again. Since the response valve (37) is opened again, raw gas is released, but in the present invention, the battery (6), the hold switch (22), the coil (4)
b), reverse current generating means (48) consisting of capacitor (47)
By this, a reverse current in the direction of the arrow is applied to the coil (4b) from the combustion stop of the burner (2) until the electromotive force of the thermocouple (5) drops below a predetermined electromotive force. Since the electromagnetic safety valve (1) is closed by setting the forward current flowing in 4b) below the holding current, no raw gas is released.

In the above embodiment, a thermocouple (49) is provided outside the thermocouple (5), both (5) and (49) are connected in opposite polarities, and this is connected to the coil (4a). Burner (2)
When is in an oxygen-deficient state, an electromotive force in the opposite direction to the thermocouple (5) is generated from the thermocouple (49), the electromotive forces of both (5) and (49) are offset, and the electromagnetic safety valve ( I tried to close 1).

(Effect of the invention) As described above, according to the present invention, from the combustion stop of the burner until the electromotive force of the thermoelectric generator becomes less than the predetermined electromotive force,
Since a reverse current is applied to the coil by the reverse current generating means to close the electromagnetic safety valve, just after the combustion of the burner is stopped, only the water is used again because only water is used. Even when the valve is opened, the release of raw gas is prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of an embodiment of the present invention.
The figure is a time chart for explaining the operation. (1) ... Electromagnetic safety valve (2) ... Burner (3) ... Gas supply path (4) ... Coil (5) ... Thermocouple (thermoelectric element) (37) ... Water pressure responsive valve (38) ... Heat exchanger (48) ) ... Reverse current generation means

Claims (1)

[Claims] 1. An electromagnetic safety valve and a water pressure responsive valve which is opened by passing water to a heat exchanger heated by the burner are provided in a gas supply path to the burner, and the heat exposed to the burner is provided. A power generation element is connected to the coil of the electromagnetic safety valve, and the electromagnetic safety valve opened in conjunction with ignition operation is held in an open state by a predetermined electromotive force generated from the thermoelectric generation element to burn the burner. In the continuous type, the coil of the electromagnetic safety valve is provided with a reverse current generating means for supplying a reverse current from the combustion stop of the burner until the electromotive force of the thermoelectric generator becomes less than a predetermined electromotive force. A combustion control device for a water heater characterized by the above.