JPH04227409A - Control of air-fuel ratio of oil fan heater and control method thereof - Google Patents

Abstract

PURPOSE: To obtain a method and a system for air/fuel ratio control of oil fan heater in which the pressure of air being fed to a burner is detected and the r.p.m. of a burner motor is controlled depending on the air pressure fluctuation in order to burn a combustion fuel completely. CONSTITUTION: Means 20 for detecting the pressure of air being fed to a burner from the rotation of a burner motor 14 is disposed in an air passage between the burner motor 14 and a burner. The burner motor 14 is subjected to r.p.m. control such that an optimal air/fuel ratio is achieved depending on the fluctuation of air pressure detected by the air pressure detecting means 20.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an air-fuel ratio control system for an kerosene fan heater and a method for controlling the air-fuel ratio for an kerosene fan heater, in which fuel supply and combustion air supply are controlled by separate electromagnetic control. An air-fuel ratio control system for a kerosene fan heater that is capable of sensing the air pressure supplied with respect to the discharge amount and controlling the rotation speed of a burner motor to achieve an optimal air-fuel ratio using a sensing signal based on a change in this air pressure. This relates to a control method.

0002

[Prior Art] A conventional air-fuel ratio control system for an oil fan heater has been designed to control the burner rotation speed in advance so that a certain amount of combustion air is supplied when a certain amount of oil fuel is supplied to the oil fan heater. was set in advance, and the burner motor was driven at the set rotation speed to supply combustion air to the burner.

However, in the air-fuel ratio control system for the kerosene fan heater configured as described above, if the rotation speed of the burner motor is set in advance, the amount of oxygen varies depending on the temperature difference of the air supplied to the burner, so the kerosene fan heater If the mechanical mechanism and burner motor characteristics are good, the optimum air-fuel ratio can be maintained, but if the mechanical mechanism and burner motor characteristics of the kerosene fan heater or the temperature characteristics of the surrounding environment change, the optimum air-fuel ratio may not be maintained. could not be mixed. Therefore, the fuel is incompletely combusted, increasing fuel consumption, making it impossible to improve the combustion efficiency of the kerosene fan heater, and causing problems in that a large amount of soot is emitted.

0004

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the various problems mentioned above, and an object of the present invention is to detect the air pressure supplied so that the fuel is completely combusted. An object of the present invention is to provide an air-fuel ratio control system for a kerosene fan heater that can control the rotation speed of a burner motor by changing the air pressure, and a method for controlling the air-fuel ratio.

[0005]

[Means for Solving the Problems] In order to achieve the above object, an air-fuel ratio control system for an oil fan heater according to the present invention provides an air-fuel ratio control system for an oil fan heater that includes a fuel supply means and an air supply means for combustion. The control system is characterized in that an air pressure sensing means for sensing heated air pressure supplied to the burner by rotation of the burner motor is provided in the air passage between the burner motor and the burner.

Further, in the air-fuel ratio control method for a kerosene fan heater of the present invention, the heated air pressure of the burner motor is measured by an air pressure sensing circuit, and when the measured value is equal to or higher than a preset constant value, the rotation of the burner motor is stopped. The air-fuel ratio is optimally controlled by decreasing the number of rotations of the burner motor and increasing the number of rotations of the burner motor when the number is below a certain value.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a circuit block diagram of an air-fuel ratio control system for a kerosene fan heater according to an embodiment of the present invention, FIG. 2 is an output voltage waveform diagram with respect to changes in air pressure of a burner motor, and FIG. 3 is a flowchart showing a procedure for controlling a fuel ratio.

In FIG. 1, reference numeral 1 denotes a microcomputer (hereinafter referred to as microcomputer) that controls all operations of fuel combustion.
2 is a constant power supply unit that supplies operating power, 3 is a key operation unit that commands the user's commands, 4 is a display unit that shows the operating status of the kerosene fan heater, and 5 is a 6 is a temperature sensor that senses the temperature of the engine and the indoor temperature, and 6 is a flame sensor that senses the flame caused by combustion of fuel.

In the drawing, reference numeral 8 denotes a heater drive section that causes the heater 7 to generate heat and heats the burner, 10 indicates an electromagnetic pump drive section that drives the electromagnetic pump 9 and supplies fuel to a burner (not shown), and 15 17 is a fan motor drive unit that drives the fan motor 13 and discharges heated air heated by a burner into the room;
This is a fan motor rotation speed sensor that detects the rotation speed of the fan motor. Also, 16 is a burner motor 14 that supplies air for combustion.
20 constitutes an air pressure sensing means that is provided in an air passage between the burner motor 14 and a burner (not shown) and senses the air pressure supplied to the burner by the rotation of the burner motor 14. This is an air pressure sensing circuit.

The air pressure sensing circuit 20 includes an amplifier 22, resistors R5 and R6 connected to the non-inverting terminal (+) of the amplifier 22, one end connected to the inverting input terminal (-), and the other end connected to the inverting input terminal (-). a constant current circuit 21 consisting of a resistor R7 connected to ground; a bridge circuit 23 consisting of resistors R1 to R4 that shapes the waveform of the output current IN of the constant current circuit 21;
and an amplifier circuit 24 that amplifies the output voltage VS of the bridge circuit 23.

In the air pressure sensing circuit 20 of the burner motor 14 configured as described above, when the output current IN of the constant current circuit 21 is supplied to the bridge circuit 23, the output changes as the pressure of the air supplied by the burner motor 14 increases or decreases. The voltage VS is expressed by the following equation [1].

[0013]

[Math 1]

[0014] Here, IN indicates a current value determined by VS/R7, which is always output from the constant current circuit 21. The output voltage VS of minute air pressure in the bridge circuit 23
As shown in FIG. 2, the output voltage Vout changes by the amplifier circuit 24 due to changes in the air pressure of the burner motor 14, and this output voltage Vout is applied to the input terminal IN6 of the microcomputer.
is input. That is, the output Vout of the air pressure sensing circuit 20 of the burner motor 14 is connected to the input terminal IN6 of the microcomputer 1.
and when the air pressure of the burner motor 14 is equal to or higher than a certain value M preset in the microcomputer 1, the burner motor drive unit 1 is input from the output terminal OUT5 of the microcomputer 1.
6 to reduce the rotational speed of the burner motor 14, and conversely, when the air pressure of the burner motor 14 is below a certain value, the output terminal OUT5 of the microcomputer 1 outputs a control signal to the burner motor drive section 16 to reduce the rotational speed of the burner motor 14. A control signal is output to increase the

The kerosene fan heater configured as described above is configured such that the key operation unit 3 is operated in a state where the constant power supply unit 2 supplies operating power.
When the kerosene fan heater is activated and an operation command is input to the input terminal IN2 of the microcomputer 1, the microcomputer 1 outputs a signal to the output terminal OUT1 to indicate on the display unit 4 that the kerosene fan heater is in operation, and also outputs a signal to the output terminal OUT1. A signal is output to OUT2 to drive the heater drive unit 8, causing the heater 7 to generate heat, thereby heating a burner (not shown). At this time, the temperature sensor 5 senses the temperature of the burner and input terminal IN4 of the microcomputer 1 is detected.
A signal related to the sensed temperature is input to the sensor.

When the temperature of the burner rises above a certain level in such a state, the microcomputer 1 outputs a control signal for driving the electromagnetic pump 9 to the output terminal OUT3 so that the electromagnetic pump 9 is driven. The electromagnetic pump drive unit 10 drives the electromagnetic pump 9 based on this control signal to inject fuel (petroleum) into the burner, drives an igniter (not shown), and ignites the fuel injected from the burner. When the petroleum fuel is ignited and starts burning in this way, the microcomputer 1 connects the output terminal O.
A fan motor drive control signal is output to the UT 4 to drive the fan motor 13.

As a result, the air heated by combustion of the fuel is discharged into the room by the drive of the fan motor 13. At this time, the microcomputer 1 outputs a control signal to the burner motor drive section 16 through the output terminal OUT5 to drive the burner motor 14.
to supply combustion air to the burner. Further, the fan motor rotation speed sensing section 17 senses the rotation speed of the fan motor 13 and sends the signal to the input terminal IN7 of the microcomputer 1.
Enter. Note that the air pressure sensing circuit 20 of the burner motor 14 senses the air pressure of the burner motor 14 and inputs the signal to the input terminal IN6 of the microcomputer 1. Then, the flame sensing section 6 measures the flame sensing voltage due to combustion of the fuel and inputs the signal to the input terminal IN5 of the microcomputer 1. This is because the burner flame temperature changes depending on the amount of combustion air supplied, which changes the air pressure of the burner motor, so the burner flame temperature is also a factor that affects optimal air-fuel ratio control.

Therefore, the optimal air-fuel ratio control system for a kerosene fan heater according to the present invention senses the air pressure of the burner motor 14 by the air pressure sensing circuit 20, determines whether or not the air pressure is equal to or higher than a certain value M, and also In some cases, the pressure of the combustion air is controlled by also taking into account the flame detection voltage sensed by the flame detection section 6, and the optimum air-fuel ratio is controlled so that the combustion air is combusted in the optimum combustion state. There is. Of course, the display section 4 can be configured to not only indicate the indoor temperature, set temperature, operating state of the key operation section 3, etc., but also indicate the driving states of the electromagnetic pump 9, fan motor 13, and burner motor 14.

FIG. 3 is a flowchart showing the procedure of the air-fuel ratio control system for a kerosene fan motor according to the present invention. In the figure, S indicates a step.

First, when the kerosene fan heater is powered on by operating a switch (not shown) with constant power being input from the constant power supply unit 2 to the input terminal IN1 of the microcomputer 1, initialization is set in step S100. . Next, the process proceeds to step S101, and when the user operates the key operation unit 3 and instructs the user's command, the key function is performed. Next, in step S102, key functions, that is, displays based on user commands are shown on the display section 4. Next, the process proceeds to step S103, where it is determined whether or not the operation switch of the key operation unit 3 has been turned on.
In the case of s, the process proceeds to step S104, where a signal is output to the output terminal OUT2 of the microcomputer 1 to drive the heater drive unit 8 to cause the heater 7 to generate heat and heat the burner. Next, the process proceeds to step S105, where the temperature sensing section 5 determines whether the heat generation temperature of the heater 7 is equal to or higher than a certain temperature (X). At this time, if the temperature is higher than a certain temperature do. On the other hand, if the operation switch is not turned on in step S103, or if the temperature of the heater is below the constant temperature X in step S105, the process returns to step S100 and the operations from step S100 onward are repeated.

Next, the process advances to step S108, and the electromagnetic pump 9, fan motor 13, and burner motor 14 are driven. Then, the electromagnetic pump 9 supplies combustion fuel,
The fan motor 13 discharges air heated by combustion of the combustion fuel into the room, and the burner motor 14 ignites and burns the fuel while supplying combustion air for the fuel to the burner.

[0022] When the fuel burns in this way, step S
After proceeding to Step 109 and checking the current air pressure H of the burner motor 14 by the air pressure sensing circuit 20, the process proceeds to Step S.
Proceeding to step 110, it is determined whether the current air pressure H is greater than a constant value M preset in the microcomputer 1. If the current air pressure H is greater than the constant value M, that is, in the case of Yes, a signal is output to the output terminal OUT5 of the microcomputer 1 to reduce the rotation speed of the burner motor 14, and then the process proceeds to step S109. Return to step S109
Repeat the following actions.

On the other hand, in step S110, the current air pressure H
is smaller than the constant value M, that is, in the case of No, the process advances to step S112, and a signal is output to the output terminal OUT5 of the microcomputer 1 to increase the rotation speed of the burner motor 14, and the process returns to step S109, where the operations from step S109 are performed. Repeat.

On the other hand, in step S110, the current air pressure H
is smaller than the constant value M, that is, in the case of No, the process advances to step S112, where a signal is output to the output terminal OUT5 of the microcomputer 1 to increase the rotation speed of the burner motor 14, and the process returns to step S109, where the operations from step S109 are performed. Repeat.

[0025]

As described above, according to the air-fuel ratio control system for a kerosene fan heater and its control method of the present invention, the air pressure is sensed by the burner flame and the burner motor's air pressure sensing circuit, and the air-fuel ratio of the kerosene fan heater is optimized. Therefore, the problem of incomplete combustion can be solved. In addition, not only can fuel consumption be reduced, but there is no problem with soot and smoke, and the combustion efficiency of the kerosene fan motor can be improved. Furthermore, by sensing the flame of the burner to control the air-fuel ratio and simultaneously sensing the air pressure of the burner motor to control the air-fuel ratio, it is possible to prevent changes in the mechanism of the kerosene fan heater, the characteristics of the burner motor, or the temperature characteristics of the surrounding environment. This has the excellent effect of being able to control the air-fuel ratio in an appropriate manner, thereby improving combustion efficiency.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an air-fuel ratio control system for an oil fan heater in an embodiment of the present invention.

FIG. 2 is an output voltage waveform diagram with respect to changes in air pressure of the burner motor.

FIG. 3 is a flowchart showing a procedure for controlling the air-fuel ratio of the oil fan heater.

[Explanation of symbols]

1 Microcomputer 2 Constant power supply section 3 Key operation section 4 Display section 5 Temperature sensor 6 Flame sensing section 7 Heater 9 Electromagnetic pump 13 Fan heater 14 Burner motor 17 Fan motor rotation speed sensing section 20 Air pressure sensing circuit 21 Constant current circuit 24 Amplifier circuit

Claims (4)

[Claims] Claim 1: An air-fuel ratio control system for a kerosene fan heater comprising a fuel supply means and a combustion air supply means, in which air is supplied to the burner by rotation of the burner motor in an air passage between a burner motor and the burner. An air-fuel ratio control system for a kerosene fan heater, characterized in that an air pressure sensing means for sensing heated air pressure is provided. 2. The air pressure sensing means includes a constant current circuit that outputs a constant current, a bridge circuit that shapes the waveform of the constant current output by the constant current circuit, and amplifies the output voltage of the bridge circuit. The air-fuel ratio control system for a kerosene fan heater according to claim 1, further comprising an amplifier circuit. 3. The constant current circuit includes an amplifier, two resistors connected to a non-inverting input terminal of the amplifier, and a resistor having one end connected to the inverting input terminal of the amplifier and the other end grounded. The air-fuel ratio control system for a petroleum fan heater according to claim 2. 4. The air pressure in the air passage between the burner motor and the burner is measured by an air pressure sensing circuit, and when the measured value is equal to or higher than a preset certain value, the rotation speed of the burner motor is reduced to a certain value. An air-fuel ratio control system for an oil fan heater, characterized in that the air-fuel ratio is optimally controlled by increasing the rotational speed of a burner motor in the following cases.