JPS6222048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the functions of a control device for combustion equipment such as oil and gas.

As the performance of combustion equipment that uses oil, gas, etc. as an energy source (forced intake/exhaust hot air heaters, etc.) improves, control that emphasizes comfort is required. As combustion efficiency increases, multi-stage combustion control and equipment development for optimal combustion control is progressing.

In the present invention, among such control functions, it is necessary to provide a combustion stop state in multi-stage combustion control when the heating load is small even at the lowest temperature setting or when the room temperature does not drop. On the other hand, the combustion control device is provided with a circuit hysteresis (differential) between the minimum temperature setting value and the combustion stop state, and also has a timer function that counts a certain period of time after entering the combustion stop state. If the lower limit temperature of the hysteresis width is not reached even after the predetermined period of time has elapsed, and the combustion state is maintained without entering the combustion state, the combustion state is forced.
While the timer is counting, if the lower limit temperature of the hysteresis is reached (within the time limit), it is natural that the count-up is automatically stopped and the combustion state is set at the same time.

By equipping the combustion control device with the above-mentioned function, the operation of the indoor convection fan will also stop when combustion stops (even if there is a post-purge function, the air blowing will need to be stopped before the air becomes cold).
Since the circulation of warm air in the room stops, indoor air stagnation occurs. Therefore, depending on the installation position of the room temperature detector, it may not be possible to issue a combustion start signal (the hysteresis limit temperature has not been reached), so the room temperature may have already reached the combustion start level. However, there may be cases where combustion cannot be achieved. In order to solve this problem, the above-mentioned time element is proposed in combination with the above-mentioned hysteresis setting.

Next, an outline of a forced intake/exhaust oil hot air heater will be explained as an example of conventional combustion equipment. FIG. 1 is a schematic configuration diagram thereof, and FIG. 2 is a control circuit diagram thereof. In FIG. 1, reference numeral 1 denotes a hot air fan case, which houses an intake unit 2, a burner unit 3, a combustion tube 4, a heat exchanger 5, an oil tank 6, a control device 7, and the like. Combustion air is taken in from the intake cylinder 11 by fans 9 and 10 that are rotated by the burner motor 8, and fuel (kerosene) is sucked up from the oil tank 6 by the pulse pump 12 and sent to the fuel supply pipe 13.
is supplied to the rotary plate 14 and atomized. A sheathed heater 16 is embedded inside the vaporizing tube 15, and the vaporizing tube is preheated to a temperature sufficient for vaporizing kerosene. Therefore, the kerosene exposed by the rotary plate 14 is vaporized by the vaporizing tube 15, mixed with air supplied by the fans 9 and 10, and sent to the combustion tube 4 from the burner head 17. An ignition electrode 18 is provided on the outlet side of the burner head 17 and ignites it. Combustion gas passes through the heat exchanger 5 from the combustion tube 4 and is exhausted outdoors through the exhaust tube 19. Reference numeral 20 denotes a combustion detection electrode (flame rod), which detects the presence or absence of a flame based on the ionic current of the flame, and detects ignition and misfire. Reference numeral 21 denotes a burner thermoswitch, which controls the energization of the vaporization heater 16. A switch 22 drives the convection fan 23 to cause convection of indoor air when the temperature of the heat exchanger 5 reaches a predetermined temperature.

The control device 7 for this warm air fan is constituted by a control circuit shown in FIG.

In FIG. 2, 24 and 25 are commercial power supply terminals. When the operation switch 26 is turned on, the operation lamp 27 lights up and the vaporization heater 16 is energized. When the temperature of the vaporizer cylinder 15 rises to a predetermined temperature, the burner thermoswitch 21 is activated and the contact point is switched from 21a to 21b. Then, the relay 28 is energized, its contact 28a is closed, and the relay 28 is self-held. At the same time, power transformer 29 is energized.
The temperature of the room (or the temperature of the intake air) is detected by a load temperature detector (thermistor) 30, and when the temperature is at which heating is required, the electronic control unit 31 closes the relay contact 32 and the burner motor 8 is energized. Then, prepurge will start. After pre-purging for a certain period of time, the relay contacts 33 and 34 are closed, and the drive circuit 36 and ignition device 37 of the pulse pump 12 are energized to ignite a spark. Combustion detection electrode 20
When ignition is confirmed, the relay contact 34 is opened, the energization to the ignition device 37 is stopped, and spark ignition is stopped. When the room temperature (temperature load) rises and reaches the set temperature, the relay contacts 32 and 33 are opened and combustion is stopped. When the room temperature drops again, the same ignition and combustion sequence as described above is executed. Note that 38, 39, and 35 are a current fuse, a temperature fuse, and an anti-seismic automatic fire extinguishing device (switch), respectively.

In this way, conventionally, combustion was performed at a fixed amount,
This is a so-called ON-OFF control in which combustion is stopped when the load temperature (room temperature) rises, and the room temperature swings within a certain hysteresis width, which is not pleasant for the user's experience. Furthermore, when the combustion is stopped, the thermo switch 22 is opened and the indoor convection fan 2 is turned off.
3 stops, the indoor air stagnates, creating a difference between the actual indoor temperature and the room temperature detection device 30. As a result, the actual room temperature reaches the hysteresis lower limit temperature of the set temperature and reaches the combustion start temperature. However, depending on the mounting position of the room temperature detection device 30, the combustion start temperature may not be reached and the combustion stopped state may continue.

FIGS. 3 and 5 are block diagrams showing an example of the present invention proposed to improve the above-mentioned drawbacks. The application numbers in FIG. 1 correspond to those in FIG. The block diagram of the combustion control device 7 includes a temperature detection circuit 50 that amplifies the signal from the thermistor 30 and includes a hysteresis circuit 50a and a timer 50b having a switching function with hysteresis, a temperature setting device 51, a flame detection circuit 52, and these circuits. A sequence control circuit 53a that operates in response to a signal from a detection circuit, and functional components, namely, a motor 8 that drives the combustion blowers 9 and 10 and a rotary plate 13, an indoor convection fan and the same motor 23, and a pulp pump 12 for refueling. The control section 53 includes a damper that varies the amount of intake air, a solenoid 48 that drives the damper, and an output circuit 53b that controls the ignition device 37.

When the power is turned on, the thermistor 30 detects the room temperature, and upon receiving this signal, the temperature detection circuit 50 compares the temperature with the temperature set by the temperature setting device 51, and if it is lower than that, sends a combustion command to the control unit 53. give.
On the other hand, since the vaporizing cylinder 4 is heated by the preheating heater 16, the burner thermoswitch 21 detects the completion of preheating and operates, and the control unit 53 drives the burner motor 8 to perform pre-purge, and then the pulse pump 12 and drives the ignition device 37. When the kerosene that has been vaporized in advance in the vaporization tube 4 is ignited by the spark from the ignition electrode 18, a flame is formed, which is detected by the flame detection circuit 52 based on the flame current signal from the flame rod 20, and set by the setting device 51. A combustion continuation command is given to the control unit 53 until the temperature T _S reached.

FIG. 4 shows the temperature change in the room temperature over time, where T _S is the temperature set by the temperature setting device, and T _L is the lower limit of temperature hysteresis of the hysteresis circuit 50a of the temperature detection circuit 7. Indicates temperature. Therefore, after the set temperature T _S is reached and the combustion is stopped at point _P1 , the convection blower 23 is turned off as described above.
Because the air also stops, convection stagnates and the temperature distribution becomes uneven. Even though the actual room temperature was below T _L due to the position of the room temperature detection device (thermistor) 30,
If the room temperature detection device 30 outputs a temperature detection signal that is higher than T _L , the actual room temperature will continue to fall without combustion occurring. At this time, the room temperature detection device 30
It stagnates at plot point _P2 . Therefore, in such a case, the timer 50b, which counts a certain period of time _t0 from the time when the set temperature _Ts is reached, commands the temperature detection circuit 50 to time up, and at the same time gives a combustion command to the control unit 53 to force the combustion sequence. By instructing the robot to enter the room, the actual room temperature can be maintained at an appropriate temperature. Incidentally, in the case of point _P3 where the room temperature detection device 30 reaches T _L during counting, the timer 50b of the temperature detection circuit 50 can of course start the combustion sequence at the same time as stopping the counter. .

As described above, according to the present invention, a more comfortable heating device is provided by reducing as much as possible the temperature detection error of the controller with respect to the actual room temperature, which is caused by the uneven distribution of room temperature that tends to occur. can do.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram of a conventional hot air heater, Fig. 2 is a control circuit diagram of the same hot air heater, Fig. 3 is a block diagram of a combustion control device showing an embodiment of the present invention, and Fig. 4. is a characteristic diagram showing the time limit setting in the same device, and FIG. 5 is a functional block diagram of the same device. 3... Burner unit (burner), 7... Control device (combustion automatic control device), 8... Burner motor, 9, 10... Fan (combustion blower), 12
... Pulse pump (fuel supply device), 23 ... Convection fan (convection blower), 30 ... Load temperature detector (indoor temperature sensor), 37 ... Ignition device (burner ignition device), 50 ... Temperature Detection circuit, 51...
...Temperature setting device (room temperature setting device), 52...Flame detection circuit, 53...Control unit (with time limit function)

Claims (1)

[Claims] 1. It has a burner, a fuel supply device, a combustion and convection blower, a burner ignition device, an indoor temperature detector, and an indoor temperature setting device, and operates these parts according to the room temperature to maintain the optimal room temperature through optimal combustion. In a combustion control device including an automatic combustion control device and having one or more combustion levels and a combustion stop state, the automatic combustion control device has a temperature detection hysteresis (differential) between the lowest combustion level and the combustion stop level. The combustion automatic control device outputs a combustion stop signal when the room temperature reaches a set temperature and a minimum combustion signal when the temperature reaches a temperature lower by the temperature detection hysteresis set in the hysteresis circuit. , has a timer that starts when the combustion stop signal is input and counts until the minimum combustion signal is input, or outputs the minimum combustion signal at a set time if the minimum combustion signal is not input within a set time. , and a control section that drives combustion functional components.