JPS5864427A - Combustion controlling device - Google Patents

Abstract

PURPOSE:To eliminate the temperature droop of hot water which may occur at re- -supply of hot water in a short time after the stop of hot water supply and consequently improve the usability of the geyser by a method wherein the prepurge action is skipped in case that the geyser once supplies hot water and stops to supply and, after that and within the definite time being, starts to supply hot water again. CONSTITUTION:In normal case that the geyser is put into operation and hot water is supplied, a relay 14 is turned OFF when a flame detecting circuit 13 detects flame. A memory circuit 67 memorizes that ignition occurred once due to said turning-OFF of the relay 14 and releases the connection of a capacitor 21, which consists of the time constant circuit of a prepurge timer in an IC combustion controlling circuit 20 and furthermore turns ON a transistor 63 through a switching circuit 66, the switching circuit 66, the switching action of which is performed by the detection of the charging voltage of a capacitor 65 comprising fail safe. In case that hot water supply is stopped under the state as just mentioned above as normal case and, after a short time, hot water is started to be supplied again, the time constant of the prepurge timer turns to be zero or the timer times up instantly resulting in opening a main valve at once in order to restart the burning of the geyser.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water heater, particularly an instantaneous gas water heater, having a hot water temperature control device that detects the hot water temperature and controls the combustion amount, and relates to a combustion control device having a pre-purge operation function. This is to improve the hot water discharge characteristics that occur when the device is applied to hot water temperature control.

Conventional instantaneous gas water heaters are often open type.The pre-purge operation function rotates the fan motor to send the unburned gas remaining in the combustion chamber out of the combustion chamber before opening the gas < i rev and igniting it with the igniter. It used to be the norm that this feature was not added, but recently outdoor forced exhaust type water heaters have appeared, and adding a pre-purge function has become essential from a safety perspective. There is.

Figure 1 shows a conventional combustion control circuit for an instantaneous gas water heater.A fan motor 1, a gas valve 2, and an igniter 3 are connected to the primary side of a power transformer T, and a rectifier 4 is connected to the secondary side.
operating switch 5, which is remotely controlled through;
An operation lamp 6 that displays the operation, a water flow switch 7 and a water flow detection circuit 8 that detect the presence or absence of water flow by a click operation, a transistor 9 that operates when water flow is detected, a fan motor drive relay 10, and a fan motor drive relay 10 that does not operate after the transistor 9 operates. The pre-purge timer circuit 11 starts, and when the timer circuit 11 times out, the relay 1 that drives the gas (lube 2)
2. A flame detection circuit 13 that detects the presence or absence of a flame, a relay 14 that controls the operation of the igniter 3, a safety switch timer circuit 15 that starts operating after the time-up of the pre-purge timer circuit 11, and a relay 16 that displays an alarm in the event of an ignition error.
, transistor 1 that cuts off the transformer secondary side control line
7. A temperature setting device 18 for setting the hot water temperature and a temperature control circuit 19 for controlling the hot water temperature are connected.

If a person who is about to use the sink or shower turns on the operation switch 5 and opens the door, the water flow switch 7
operates, the fan motor drive relay 10 operates, and the fan motor 1 begins to rotate (prepurge operation). The water flow detection circuit 8 detects that the water flow switch 7 has been operated, and the transistor 9 is turned on. As a result, the pre-purge timer circuit 11 starts to operate, and at the same time, the relay 14 that controls the operation of the igniter 3 is operated. The igniter 3 does not spark at this point due to the load contact configuration on the next side of the transformer. When the pre-purge timer circuit 11 times up, the gas valve drive relay 12 operates, and the gas valve 2 and igniter 3 operate to attempt ignition. When the flame is ignited, the flame detection circuit 13 detects the flame, and the relay 14, which controls the operation of the igniter 3, returns to its original state, resulting in a steady combustion state. Thereafter, the temperature control circuit 19 controls the hot water temperature according to the temperature setting device 18, and the user uses the sink or shower.

When the user finishes using the washbasin or shower, the water flow switch 7 is normally turned back on to close the flusher, and the transistor 9 is also turned off, so the fan motor 1 and the gas valve 2 are turned off.
, the igniter 3 stops.

Immediately after that, when I opened the door to use the washroom again,
The combustion control circuit attempts the ignition sequence again from the pre-purge operation to try to obtain the proper temperature.

However, at the time of this re-ignition, due to the aforementioned pre-purge operation function, the water circuit of the water heater is as shown in Figure 2: the remaining hot water portion a, and the unheated water portion that entered the water heater water circuit during the pre-purge operation. vinegar.

Hot water portion CKj heated by the burner after pre-purge operation
Because the hot water comes out from the faucet in an external part, the temperature of the hot water is lukewarm (remaining hot water), cold (
The problem was that it was difficult to use because it varied greatly between warm water (during pre-purge operation), lukewarm water (early stage of steady combustion), and moderate temperature water (steady combustion).

In order to eliminate this inconvenience, the present inventors first provided a pilot burner and a main burner, and turned on and off the main burner by turning on and off a water flow switch, and at the same time, stopped the hot water supply and turned off the main burner. He devised and applied for a combustion control device that ignites the pilot burner for a certain period of time (for example, 5 molecules'), and if hot water is tapped again within this period, the main burner is immediately ignited without performing a pre-purge operation. Patent application 1527-1983
14). However, this combustion control device requires a pilot burner in addition to the main burner, making the structure of the device complicated.Also, the pilot burner is ignited for a certain period of time even after hot water has stopped dispensing, resulting in increased gas consumption and other inconveniences. there were.

In view of the above-mentioned problems in the conventional example, the present invention is based on the idea that the combustion control device performs a pre-purge operation when the hot water is re-discharged within a certain period of time after the hot water has been discharged. To provide a simple and economical combustion control device which eliminates a drop in hot water temperature when hot water tap is restarted.

The present invention will be described in detail below using the drawings.

Note that parts common or corresponding to those of the conventional example are represented by the same reference numerals.

FIG. 4 is a block diagram showing a circuit of a combustion control device according to an embodiment of the present invention, FIG. 5 is a circuit diagram showing a part of this device in more detail, and FIG. In the schematic diagram shown in FIG. 4 showing the structure of a water heater, there are 20 IC combustion control circuits, a pre-purge timer circuit 11, a safety switch timer circuit 15, a part of the flame detection circuit 13, and relay coils 12 and 14 shown in FIG. This is an IC circuit including a relay driving element, and controls the relays 12, 14 and 16. The capacitor 21 constitutes a time constant of a pre-purge timer circuit connected to the IC and the combustion control circuit 20.

These relays and most other structures are similar to those shown in FIG. 1, and only the different parts will be described below. The flame detection circuit 13 is connected to the frame rod 53. A timer circuit 22 is connected to the water flow switch 7 instead of the water flow detection circuit 8. This timer circuit 22 has a timer time of 5 minutes in this embodiment, and the water flow switch 7
When is on, the timer does not operate, but its output turns on transistor 9, and water flow switch 7 turns off.
When this happens, the timer operation is started and the transistor 9 is kept on until the time is up, and after the time is up in 5 minutes, the transistor 9 is turned off and the power supply to the subsequent circuits is cut off. The air flow switch (AFS) 25 is turned ON when it detects rotation or stop of the fan motor l due to ON or OFF of the water flow switch 7.

0FFL operates substantially the same as transistor 9 in FIG. The PID temperature control circuit 27 is connected to a series circuit of the thermistor 51 and the temperature setting device 18 (which may be a variable resistor), and provides an output to the valve drive circuit 29 so that the gas amount is controlled according to the water temperature. , the valve drive circuit 29 adjusts the proportional valve 44 according to this output.Slow ignition circuit 2
8 gives a constant output to the valve drive circuit 29 regardless of the output of the PID temperature control circuit 27, so that the proportional valve 44 has a predetermined valve opening degree, and a suitable amount of gas is supplied for slow ignition. I have to. Combustion lamp 31, flame detection circuit 13
It is turned on by the lighting circuit 30 when the lamp detects flame. The memory circuit 67 is, for example, a flip-flop set by the output of the flame detection circuit 13, and stores the fact that ignition has been detected until the timer circuit 22 times up and the power is cut off by the transistor 9. Resistance 61, 64,
The capacitor 65, the transistor 63, and the switching circuit 66 constitute a fail-safe circuit 70 of a drive circuit for the relay coil 12. That is, the resistor 61 is set to a sufficiently larger resistance value than the relay coil 12, and when the relay 12 is grounded due to an abnormal operation of the IC combustion control circuit 20 (for example, a short circuit of the relay drive element) when the power is turned on, the resistor 61 is set to a sufficiently larger resistance value than the relay coil 12. The terminal voltage of the relay 12 side of the switching circuit 61 becomes lower than the ON level of the switching circuit 66.
6. Therefore, the transistor 63 is 0FFL, and only a small current flows through the relay 12 via the resistor 61, so that it does not operate. On the other hand, during normal operation, the relay 12 is open during the prepurge operation, so the capacitor 65 is charged via the resistor 61, and when the terminal voltage exceeds the ON level of the switching circuit 66, the switching circuit 66 and therefore the transistor 63 are turned ON. Since the resistor 61 is short-circuited, when the pre-purge operation is completed and the relay drive element is turned on, the relay 12
works. The alarm holding circuit 23 is the x5 combustion control circuit 20
When the safety switch timer circuit that can be used generates an output and the relay 16 is turned ON, the alarm state of the buzzer 24 is maintained and the contact Xsb is maintained OFF.

As shown in FIG. 6, gas is supplied to the main bar 45 through the main valve 2, the gas governor 43, and the proportional valve 44 in this order. The igniter 3 and fan motor 1 to which the shives and ignition electrode 54 are connected include a thermistor 51 for water temperature detection, a water flow switch 7, and a frame rod 5.
The combustion control device is controlled by the combustion control device having the circuit configuration shown in FIG.

The operation of the gas instantaneous water heater shown in Figures 4 to 6 is as shown in the time chart in Figure 7, and when the operation switch 5 is turned ON and the ignition sequence is started from the beginning, the operation is as described above. is the same as However, once you take a bath,
When steady combustion starts and the flame detection circuit 13 detects a flame and the relay 14 is turned off, the memory circuit 67 remembers that ignition has occurred and opens the connection of the capacitor 21 that constitutes the time constant circuit of the pre-purge timer. , the transistor 63 is turned on via a switching circuit 66 that detects and switches the charged voltage of the capacitor 65 that constitutes a fail-safe, and operates to reduce the series impedance of the resistors 61 and 64 to only the impedance of the resistor 64. . Once the ignition occurs, the memory circuit memorizes it, and when the flame disappears when the bell is closed, the flame detection circuit 13
maintains memory even when it detects a newcomer. This storage continues until the timer circuit 24 times up and the power supply voltage of the storage circuit runs out. In order to operate as described above, if the flusher is closed and the flusher is opened again within 5 minutes after the hot water is discharged through steady combustion, the timer circuit 22 will start when the water flow switch 7 is turned OFF in response to the flusher being closed. However, even if the turn is closed, the transistor 9 is kept ON for 5 minutes, so when the turn is restarted, the time constant of the pre-purge timer becomes O and the time-up instantaneously occurs, and the transistor 63 is also turned on, so the pre-purge time is - In this state, the main valve 2 immediately opens to attempt ignition. In this way, when restarting within 5 minutes after the flush is closed, the main burner is immediately ignited without pre-purge operation, so there is no drop in water temperature and the water temperature remains stable like Ilharuni in Figure 3. be able to.

In addition, if there is more than 5 minutes in Karan's restart circuit ■Circuit 2
2 turns off, the transistor 9 turns off, the memory circuit 67 also returns to its initial state, and the same sequence as at the time of first ignition is performed.

As described above, according to the present invention, when hot water is used intermittently at short intervals, the pre-purge time is shortened and the main burner is ignited, so it is possible to eliminate drops in the hot water temperature.
In addition, when the hot water is initially ignited or when the hot water is re-discharged after a certain period of time, the ignition is performed after performing a pre-purge operation, and there is no need to add a pilot burner to the combustion equipment as in the case of conventional methods, and the burner is completely turned off each time. As a result, it is possible to provide a combustion device that is easy to use, safe, and has a simple structure, and also realizes an economical gas water heater.

Note that FIGS. 4 and 5 show the case where there is a fail-safe (short-circuit failure detection) for the drive circuit of the Xp relay 14, but if there is no fail-safe (short-circuit failure detection), the connection of the capacitor 62 that constitutes the time constant of the LePage timer circuit Of course, it is sufficient to simply release the .

Also, in order to reduce the delay time of the solepurge timer circuit, the capacitor that makes up the time constant of the prepurge timer θ may be disconnected as shown in dC above, but the resistor that makes up the time constant of the prepurge timer can be disconnected. The impedance may be reduced in accordance with the method used in the fail-safe circuit in the above embodiment.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional circuit, Fig. 2 is a schematic diagram of a water circuit of a water heater, Fig. 3 is a time chart of hot water temperature, and Fig. 4 is a block diagram of a circuit according to an embodiment of the present invention. 5 is a partial detailed circuit diagram of the embodiment, FIG. 6 is a schematic diagram of the structure of a water heater to which the embodiment is applied, and FIG. 7 is a time chart showing the operation of the embodiment. . l...Fan motor, 2...Main valve, 3...Igniter, 7...Water flow switch, 12...Relay (coil) , 13・
...Flame detection circuit, 20...IC combustion control circuit, 21...Capacitor, 22...
・Timer circuit, 44... Proportional valve, 53...
・・Frame Rondo, 54・・Old・・Ignition electrode, 61°6
4...Resistor', 63...Transistor, 65...Capacitor, 66...Switching circuit, 67...Memory circuit Patent applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Tatsuo Ito 〃 Tetsuya Ito

Claims (1)

[Scope of Claims] L: A prepurge timer circuit is provided, and the prepurge timer circuit is started at the start of operation, the fan motor is operated until the prepurge timer circuit times up to perform the prepurge operation, and the ignition is performed after the prepurge operation is completed. In the combustion control device that controls the operation, confirms ignition, and shifts to steady combustion operation, there is a water flow switch that detects the stop and start of hot water dispensing, and a water flow switch that operates according to the output signal of this water flow switch and starts from the time the hot water dispensing stops. and a timer circuit that performs a time amplification after a predetermined period of time, the delay time of the pre-purge timer circuit is reduced until the timer circuit times out, and when hot water starts to be tapped again within this time, the pre-purge timer circuit A combustion control device characterized in that the time-up is performed in a short period of time and then the ignition operation is started. 2. The combustion control device according to claim 1, wherein the delay time of the prepurge timer circuit is reduced by reducing the impedance of a resistor that constitutes a time constant of the prepurge timer. 3. The combustion control device according to claim 1, wherein the delay time of the prepurge timer circuit is reduced by disconnecting a capacitor that constitutes a time constant of the prepurge timer. 4. Recite the pre-purge timer circuit, start the pre-purge timer circuit at the start of operation, operate the fan motor to perform the pre-purge operation until the pre-purge timer circuit times out, and move on to the ignition operation after the pre-purge operation is completed. In a combustion control device that controls ignition and shifts to steady combustion operation, there is a water flow switch that detects the stop and start of hot water dispensing, and a water flow switch that operates according to the output signal of this water flow switch and starts from when hot water dispensing stops and a predetermined time later. A timer circuit that times up, a relay drive element controlled by the prepurge timer, a relay coil connected in series to this relay drive element, a capacitor connected in parallel to this relay drive element and the series circuit of the relay coil, and a capacitor connected in series to this capacitor. A resistor that is connected to form a time constant circuit, a switching circuit that detects and switches the charging voltage of the capacitor, and a switching circuit that is driven to reduce the impedance of the resistor that forms the time constant circuit in accordance with the switching of this switching circuit. A switching element is provided to reduce the delay time of the pre-purge timer circuit until the timer circuit, which starts from the time the hot water tap is stopped and times up after a predetermined time, and to reduce the delay time of the pre-purge timer circuit, and to reduce the delay time of the pre-purge timer circuit, and A combustion control device characterized in that when impedance is reduced and hot water starts dispensing again within this time, the pre-purge timer circuit is timed up in a short time and the relay coil is driven to proceed to ignition operation. 5. The combustion control device according to claim 4, wherein the delay time of the prepurge timer circuit is reduced by reducing the impedance of a resistor that constitutes a time constant of the prepurge timer. 6. The combustion control device according to claim 4, wherein the delay time of the prepurge timer circuit is reduced by disconnecting a capacitor that constitutes a time constant of the prepurge timer. 7. A timer circuit that operates in response to the output signal of the water flow switch and starts when hot water is stopped and times up after a predetermined period of time reduces the time constant of the pre-purge timer during operation, and A signal that reduces the impedance of a resistor connected in series with a capacitor connected in parallel to the series circuit of the water current switch to form a time constant circuit detects ignition until a timer circuit operating in accordance with the output signal of the water flow switch times up. The combustion amount/leg device according to claim 4, wherein the output signal is an output signal of a memory circuit that temporarily stores information.