JPS6146726B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device that controls the combustion output of a burner according to load.

Conventionally, this type of device has a solenoid valve, a proportional control valve, and a side path parallel to the control valve interposed in the gas supply path of the burner, and also generates a comparative output by comparing the temperature of the heated part and the set temperature. A temperature control circuit is provided to
The proportional control valve is controlled to open and close according to the comparison output, and the amount of gas supplied to the burner is set to the minimum allowable gas amount that is supplied via the bypass when the control valve is closed, and the control Proportional control valves are known that can be adjusted steplessly between the maximum amount of gas supplied when the valve is fully open, but there is a limit to the amount of gas that can be adjusted by a proportional control valve. Furthermore, since the burner is also limited in its allowable maximum gas amount, it is not possible to widely vary the combustion output with this burner.

In this case, multiple burners are provided, and a solenoid valve, a proportional control valve, and a side passage are interposed in each separate gas supply path leading to each burner, and the proportional control valve is fully opened by the total output of each burner. It may be possible to increase the maximum output when the proportional control valve is closed, but in this case, if the solenoid valves of each supply path are controlled to open and close at the same time, the minimum output when the proportional control valve closes will also be equal to the total output of each burner. Therefore, it is desirable that the solenoid valves in each supply path be opened sequentially so that when one burner is insufficient in output, the other burners are fired, and the solenoid valves in each supply path are opened later. It is desirable to prevent explosive ignition in burners to which gas is supplied via solenoid valves.

An object of the present invention is to provide an apparatus that satisfies such demands, and includes a pilot burner and at least two first and second main burners, and a first gas connected to the first main burner. A first solenoid valve, a first proportional control valve, and a side passage parallel to the first proportional control valve are interposed in the supply path, and the second
A second solenoid valve, a second proportional control valve, and a side path parallel to the second proportional control valve are interposed in the second gas supply path leading to the main burner, and further the heating temperature of the heated part and the set temperature are adjusted. A temperature control circuit is provided that generates a comparison output by comparing the two proportional control valves, and the first and second proportional control valves are controlled to open and close according to the comparison output. A valve open detection circuit that detects the increase in pressure of the pilot burner, and a step-down circuit that is activated by the detection output from the detection circuit to temporarily step down the comparison output to a level at or near the fully closed state are provided. The first electromagnetic valve is opened by ignition, and the second electromagnetic valve is opened by activation of the step-down circuit.

Next, one example of implementing the present invention will be explained with reference to attached drawings.

FIG. 1 shows a water heater as a combustor equipped with the device of the present invention. An exchanger 2, a pair of first and second main burners 3-1 and 3-2 arranged in parallel below the exchanger 2, a pilot burner 4 provided so as to straddle both burners 3-1 and 3-2, and The combustion fan 6 is provided in an exhaust pipe 5 extending above the housing body 1.

The first and second main burners 3-1 and 3-2 each supply gas separately through a first gas supply path 8-1 and a second gas supply path 8-2 that branch from a common main gas supply path 7. A main solenoid valve 9 and a governor 10 are connected to the main gas supply path 7, and the first gas supply path 8-
1, the first solenoid valve 11-1 and the first proportional control valve 12
-1, a side passage 13-1 parallel to this, a second solenoid valve 11-2, a second proportional control valve 12-2, a side passage 13-1 parallel to this, and a second solenoid valve 11-2, a second proportional control valve 12-2, and a side passage 13-1 parallel to this Further, a gas supply path 14 leading to the pilot burner 4 is branched from the downstream side of the main solenoid valve 9 of the main gas supply path 7, and a pilot solenoid valve 15 is connected thereto.
mediated.

Figure 2 shows the circuit of the device of the present invention, which includes a commercial power supply, a transformer, a rectifier circuit, and a main switch.
a control unit 17 connected to the power source via a control unit 17, and a controlled unit ₁₈ for the combustion fan 6 connected to the power source via a relay switch _r1 of a first relay R1 to be described later;
It consists of a second controlled section 19 connected to the power source via the relay contact _r1 , a rectifier circuit, and a relay switch _r2 of a second relay _R2 to be described later.

The second controlled section 19 includes a relay switch r ₂
The main solenoid valve 9 is always energized when the circuit is closed, the pilot solenoid valve ₁₅ is energized via the relay switch _R3 of the third relay R3 (described later), and the fourth relay _R4 (described later). The igniter 2 on the normally closed contact side is energized via switch _R4 .
The first solenoid valve 11-1 on the normally open contact side and the second solenoid valve 11-2 were connected so as to be energized via a relay contact _r5 of a fifth relay _R5 to be described later. In FIG. 1, 20a indicates an ignition electrode on the output side of the igniter 20.

The controlled part 18 for the combustion fan 6 includes a relay switch R 6 of a sixth relay R ₆ to be described later, and its normally closed contact side causes the fan ₆ to rotate at a low speed, and its normally open contact side causes the fan 6 to rotate at a low speed. It was designed to provide high-speed rotation.

The control unit 17 controls the first to sixth relays R ₁ ,
R ₂ ......R ₅ drive circuits 21, 22...26
and compares the temperature sensing output A from the thermistor 27 that detects the heating temperature of the heated part 2 with the temperature setting output B from the temperature setting resistor 28 and generates a comparison output C according to the difference. A control circuit 29;
The first and second proportional control valves 12-1 and 12 use the widening region of the transistor 30 that inputs the comparison output C.
A proportional control circuit 31 that controls the opening and closing of -2 to an opening degree according to the comparison output C, and compares the temperature sensing output A and the temperature setting output B, and when the output A is higher than the output B, the Temperature rise/fall detection circuit 32 that generates output D
and a valve open detection circuit 33 that generates a detection output E of "1" when the comparison output C rises to a predetermined fully open level VH, and a valve open detection circuit 33 that generates a detection output E of "1" when the comparison output C rises to a predetermined fully closed level VL. A valve closing detection circuit 34 that generates a detection output F is provided.

The temperature control circuit 29 has a temperature sensing output A and a temperature setting output B.
and an arithmetic amplifier that inputs each, and a CR on its output side.
A capacitor 35 constituting a timer and a seventh relay to be described later that closes a discharge circuit of the capacitor 35.
The control unit 17 is provided with a relay switch r ₇ of R ₇ and a relay switch r ₈ of an eighth relay R ₈ to be described later that closes the charging circuit of the capacitor 35.
Then, the seventh relay _R7 is driven to connect the capacitor 3.
A step-down circuit 36 that discharges the capacitor 35 and steps down the comparison output C obtained as the charging potential to a level at or near the fully closed state, and drives the eighth relay _R8 to charge the capacitor 35 and perform the comparison. Output C
A booster circuit 37 is provided to boost the voltage to a fully open level or a level close to that level.

To explain this in more detail, the step-down circuit 36 receives the detection output E from the valve open detection circuit 33, the output D from the temperature rise/decrease detection circuit 32, and the outputs of the step-down circuit 36 and the step-up circuit 37. The inverted output from the flip-flop 38 that inputs J and K is connected to an AND circuit that receives each input, and a seventh relay on the output side.
The booster circuit 37 is composed of a transistor for conducting _R7 , and the booster circuit 37 receives the detection output F from the valve closing detection circuit 34, the inverted output from the temperature rise/decrease detection circuit 32, and the output Q from the flip-flop 38.
and the input AND circuit and its output side 8th
Relay R consists of ₈ conduction transistors. The drive circuit 21 of the first relay _R1 , the detection output F from the valve closing detection circuit 34, and the flip-flop 3
The drive circuit 22 of the second relay R2 is composed of a NAND circuit that inputs the inverted output from 8 and a transistor for conducting the first relay _R1 on _the output side.
consists of a delay circuit that generates an output H of "1" after a certain purge time has elapsed after the wind pressure switch 39 in the exhaust stack 5 in FIG. 1 is closed, and a second relay R ₂ on the output side of the delay circuit.
It consists of a transistor for conduction, and the third relay
The drive circuit 23 of R ₃ is composed of a first timer element 40 , a second timer element 41 , and a transistor for conducting the third relay R ₃ on the output side of each timer element 40 , 41 . , the output I of the drive circuit 24 of the fourth relay _R4 , the output M of which will be described later.
When the output I is "0", it becomes "1", and when the output I becomes "1", it operates to set it to "0" several seconds later, and the second
The timer element 41 operates so that its output N becomes "1" for several seconds when the output L of the drive circuit 25 of the fifth relay _R5 , which will be described later, becomes "1".

The drive circuit ₂₄ for the fourth relay _R4 includes a flame detection circuit that is activated by a signal from the flame rod 42 shown in FIG. The drive circuit 2 of the fifth relay _R5 is composed of a general-purpose transistor.
5 is an AND circuit which receives the output Q of the flip-flop 38 and the output I of the drive circuit 24 of the fourth relay _R4 and generates an output L, and a transistor on the output side of the AND circuit for making the fourth relay _R4 conductive. The drive circuit 26 of the sixth relay _R6 connects the output I of the drive circuit 24 of the fourth relay _R4 and the drive circuit 26 of the sixth relay R6.
It is composed of a coincidence circuit that receives the output L of the drive circuit 25 of _R5 , and a transistor for conducting the sixth relay _R6 on the output side thereof.

Next, its operation will be explained based on the time chart shown in FIG.

First, when the main switch 16 is closed at time _t0 , a temperature sensing output A and a temperature setting output B are generated.
In this case, since the temperature sensing output A is higher than the temperature setting output B, a relatively large output is generated from the operational amplifier of the temperature control circuit 29, and the comparison output C obtained as the charging potential of the capacitor 35 increases sequentially. Being done,
When this becomes equal to or higher than the fully closed level VL, the output F of the valve closing detection circuit 34 becomes "0", and the first relay R ₁
The output G of the NAND circuit provided in the drive circuit 21 becomes "1", _the first relay R1 is energized, the relay switch _R1 is closed, and the controlled part 18 for the combustion fan 6 is energized. Ru. In this case, the output 0 of the coincidence circuit provided in the drive circuit 26 of the sixth relay R ₆ means that the outputs I and L input thereto are both "0".
Therefore, it becomes "1", and the sixth relay R6 is energized and the relay switch _R6 is switched to the normally open contact side, thus allowing the combustion fan ₆ to operate at high speed. According to this, the residual gas in the casing body 1 is quickly purged to the outside, and an explosion and ignition caused by the residual gas at the time of subsequent ignition is reliably prevented.

Further, when the combustion fan 6 is operated, the wind pressure switch 39 is closed, and the drive circuit ₂ of the second relay R2 is closed.
After the predetermined purge time elapses, the output H of the delay circuit provided in step 2 becomes "1", and the relay switch _R2 is closed by energizing the second relay _R2 , and the second controlled part 19 is energized. main solenoid valve 9
is opened.

At this time, the output M of the first timer element 40 provided in the drive circuit 23 of the third relay R ₃ becomes "1" because the output I input thereto is "0", and the output M of the first timer element 40 provided in the drive circuit 23 of the third relay R ₃ becomes "1". Its relay switch R ₃ by energizing
is closed, the pilot solenoid valve 15 is opened, and the igniter 20 is energized via the normally closed contact of the relay switch _R4 of the fourth relay _R4 to ignite the pilot burner 4. be done.

According to this ignition, the signal from the flame rod 42 is input to the flame detection circuit provided in the drive circuit 24 of the fourth relay _R4 , and the flame detection output I becomes "1", and the energization to the fourth relay R4 causes the flame detection output I to become " ₁ ". The first solenoid valve 11-1 is opened by switching the relay switch _r4 to the normally open contact side, and the first main burner 3-1 is opened via the side passage 13-1 and the first proportional control valve 12-1.
1 is supplied with gas, and a pilot burner 4 is supplied to it.
ignition is given by ignition.

Then, when the flame detection output I becomes "1", the sixth
The output 0 of the matching circuit provided in the drive circuit 26 of the relay R ₆ becomes "0", the relay switch R ₆ of the sixth relay R ⁶ returns to the normally closed contact side, and the combustion fan 6
is given a low rotation speed, and the ventilation amount inside the housing body 1 is
The amount is reduced to an amount suitable for independent combustion in the main burner 3-1. Furthermore, when the output I becomes "1", the output M of the first timer element 40 becomes "0" several seconds later, and the relay switch _r3 of the _third relay R3 is opened.
The pilot solenoid valve 15 is closed and the pilot burner 4 is extinguished.

Thereafter, the combustion output of the first main burner 3-1 is adjusted by controlling the opening of the first proportional control valve 12-1 according to the comparison output C, and a constant amount of air is supplied to the heat exchanger 2, which is the heated part. With water, the combustion output is stabilized at a predetermined level at which the water temperature T remains approximately constant.

Next, when the temperature setting resistor 28 is reset to the high temperature side at time _t1 , the difference between the temperature sensing output A and the temperature setting output B increases to the positive side, and the comparative output C rises again, which is the full open level. When the voltage is increased to VH and the output E of the valve open detection circuit 33 becomes "1", the outputs D and E, which are input to the AND circuit provided in the step-down circuit 36, all become "1", and the AND circuit Output J becomes "1", thus the 7th relay
The relay switch _R7 of _R7 is closed, the capacitor 35 is discharged, and the comparison output C is at the fully closed level.
When the voltage is reduced to the vicinity of VL and the output J becomes "1", the output Q of the flip-flop 38 becomes "1".
Then, the output L of the AND circuit provided in the drive circuit 25 of the fifth relay _R5 which inputs the output Q and the flame detection output I becomes "1", and the relay switch is activated by energizing the fifth relay _R5 . Given a cycle of r ₅ ,
The second electromagnetic valve 12-2 is opened, gas is supplied to the second main burner 3-2, and the second main burner 3-2 is ignited.
In this case, the first and second proportional control valves 12-1, 12-2
is almost in a closed state due to the reduction of the comparison output C to near the fully closed level VL due to the operation of the step-down circuit 36, so the amount of gas supplied to the second main burner 3-2 is reduced to the side path 13-2. 2 becomes the minimum amount through
Explosive ignition of the second main burner 3-2 does not occur.

Incidentally, when the output J of the AND circuit of the step-down circuit 36 becomes "1" and is input to the flip-flop 38, the inverted output of the flip-flop 38 input to the AND circuit becomes "0".
Output J is returned to "0" and therefore the seventh relay R ₇
relay switch _R7 is opened, the comparison output C is sequentially increased, and the first and second proportional control valves 12-1, 12
The opening degree of -2 is accordingly increased, and heating is performed at high output by both the first and second main burners 3-1 and 3-2. Furthermore, when the output J becomes "1", the output N of the second timer element 41 provided in the drive circuit 23 of the third relay _R3 becomes "1" for several seconds, and the output of the third relay R3 becomes "1".
The pilot solenoid valve ₁₅ is opened by closing the relay switch R3 of _R3 . According to this, the pilot solenoid valve 15 is opened so that the pilot burner 4, which is disposed astride the first and second main burners 3-1 and 3-2, is opened. By supplying gas,
Reliable ignition from the first main burner 3-1 to the second main burner 3-2 can be achieved via the pilot burner 4.

Further, when the output J becomes "1", the output 0 of the matching circuit provided in the drive circuit 26 of the sixth relay _R6 that inputs the output J and the flame detection output I becomes "1", and the output of the sixth relay R6 becomes "1". The relay switch _r6 of ₆ is switched to the normally open contact side, and the combustion fan 6 is given high-speed rotation, so that the ventilation amount inside the housing 1 is equal to that of both the first and second main burners 3-1 and 3-2. Increased amount suitable for combustion.

Next, at time _t2 , when the temperature setting resistor 28 is set to the low temperature side again, the difference between the temperature sensing output A and the temperature setting output B increases to the negative side, and the comparison output C decreases, which is the fully closed level. When the voltage decreases to VL and the output F of the valve closing detection circuit 34 becomes "1", the outputs F and Q input to the AND circuit provided in the boost circuit 37 all become "1", and the output of the AND circuit becomes "1". Output K becomes "1", thus the 8th relay
The relay switch _R8 of _R8 is closed, the capacitor 35 is charged, and the comparison output C is at the fully open level.
When the voltage is boosted to the vicinity of VH and the output K further becomes "1", the output Q of the flip-flop 38 becomes "0" and is ready for the drive circuit 25 of the fifth relay _R5 .
When the output L of the AND circuit becomes "0", the relay switch _R5 of the fifth relay _R5 is opened, and the second solenoid valve 1
2-2 is closed, combustion is shifted to only by the first main burner 3-1, and at the same time, the sixth relay R ₆
The output 0 of the coincidence circuit provided in the drive circuit 26 becomes "0", the relay switch _r6 returns to the normally closed contact side, and the combustion fan 6 is switched to low speed rotation.

At this time, in order to prevent the output G of the NAND circuit provided in the drive circuit 21 of the first relay _R1 from becoming "0", the output F becomes "1" and the flip-flop 3
When the inverted output of 8 becomes "1", the inverted output is input to the NAND circuit with a delay by a delay element (not shown), and during that time, the output F becomes "0" by the above charging. I made it back.

Next, at time _t3 , when the temperature setting resistor 28 is further set to the lower temperature side, the difference between the temperature sensing output A and the temperature setting output B increases to the negative side again, and the comparison output C
decreases to the fully closed level VL, and when the output F of the valve closing detection circuit 34 becomes "1", the output F, which is input to the NAND circuit provided in the drive circuit 21 of the first relay _R1 , both becomes "1". 1, the output G becomes 0, the relay switch _r1 of the first relay _R1 is opened, and the controlled part 1 for the combustion fan
8 and the second controlled section 19 are cut off,
The state returns to the state when the main switch 16 was turned on.

In addition, in the above embodiment, each main burner 3-
1 and 3-2, for example, each proportional control valve 12-1, 12
-2 when it is closed, and 16,000 Kcal, which is twice that when it is fully open, when the second main burner 3-2 is ignited, each proportional control valve 12-1, 12- 2 is almost closed, the total output from the first and second main burners 3-1 and 3-2 is at the time of ignition.
The result is 16000Kcal, which matches the output of 1600Kcal of the first main burner 3-1 before ignition, and eventually
Continuous output control over a wide range from 8000Kcal to 32000Kcal is possible.

As described above, according to the present invention, the first solenoid valve is first opened to operate the first main burner, and when the comparative output increases to a level at which the proportional control valve is fully opened, the comparative output is temporarily The pressure is lowered to near the fully closed level, and the second solenoid valve is opened to open the second solenoid valve.
This is designed to start the operation of the main burner, making it possible to control the output over a wide range from the minimum output of the first main burner to the total maximum output of the first and second main burners. This has the advantage that it is carried out with the minimum amount of gas and does not cause explosive ignition.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view of a combustor to which the device of the present invention is applied, FIG. 2 is a block diagram showing the circuit of the device of the present invention, and FIG. 3 is a time chart illustrating its operation. 2... Part to be heated, 3-1, 3-2... First second
Main burner, 4...Pilot burner, 8-
1, 8-2...first and second gas supply path, 11-1,
11-2...first and second solenoid valve, 12-1, 12-
2...First and second proportional control valves, 13-1, 13-2
... Side path, 29 ... Temperature control circuit, 33 ... Valve open detection circuit, 36 ... Step-down circuit.

Claims (1)

[Claims] 1 comprising a pilot burner and at least two first and second main burners, a first solenoid valve, a first proportional control valve, and the first proportional control valve in a first gas supply path leading to the first main burner; A second gas supply path leading to the second main burner is provided with a second solenoid valve, a second proportional control valve, and a second gas supply path connected to the second main burner.
A parallel side path is interposed in the proportional control valve, and a temperature control circuit is provided that compares the heating temperature of the heated part with a set temperature and generates a comparative output, and the first and second proportional control valves are connected to the proportional control valve. In a valve opening/closing control device that controls opening and closing according to a comparison output, there is a valve open detection circuit that detects a rise in pressure of the comparison output to a fully open level, and a valve opening detection circuit that is activated by the detection output from the detection circuit to control the comparison output. A step-down circuit is provided to temporarily reduce the voltage to a fully closed level or a level close to it, and when the pilot burner is ignited, the first solenoid valve is opened, and when the step-down circuit is activated, the second solenoid valve is opened. A combustion control device characterized in that a valve is opened.