JPS6259308A - Control device for room heater - Google Patents

Abstract

PURPOSE:To prevent loss of balance in between the combustion gas and fuel by using a fuel supply device which changes the fuel discharge amount according to the pulse state and at the same time providing a pulse delaying section at a control section which controls the combustion air and fuel, which delaying section gradually changes pulses to a fuel supply device. CONSTITUTION:When signals inputted to the terminals AN1, AN2, and AN3 of a microcomputer 12 are compared at a comparison section 27, and it issues signals of 'strong' or 'weak' or 'off', the burner motor control section 30 changes over burner motor 3. At the same time the signal from the comparison section 27 is sent to a pulse delaying and changing section 31, and this changing section drives a drive circuit 4' through a photo-coupler 20 to actuate a pump 4. This changing section 31 compares the signals from a pulse generating section 32 and a target pulse setting section 33 at a comparison and detection section 34, and the cycle that difference in the comparison is corrected little by little at a correction section 35 to feed a corrected difference back to the pulse generating section 32 is repeated in order to make the pulse approach a target pulse gradually. With this arrangement it is possible to limit the air and fuel ratio to minimum when the combustion amount is changed over.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a control device for a hot air heater such as a kerosene fan heater, and particularly to control of fuel and air when switching the combustion amount.

Conventional technology Generally speaking, when trying to change the combustion amount according to the room temperature detection element, it is necessary to change the combustion air and fuel at the same time so as not to disrupt the air-fuel ratio. ), and at the same time the frequency of the pump (hereinafter referred to as pulse pump) used as a fuel supply device was also changed. An example of the circuit is shown in FIG. 6, where 51 is a power source, 52 is a power switch, 53 is a combustion control section, 54 is a burner motor,
55 is a pulse pump, 56 is a relay connected to the power supply 51 via the room temperature detection element 57, and has relay contacts 58 and 59 for switching the burner motor 54 and the pulse pump 55 in two stages of strength. ○N-0
The burner motor 54 and pulse pump 55 are switched simultaneously by the FF.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, there was a problem in that when the combustion amount was changed, the ratio of combustion air to fuel was temporarily disrupted, resulting in deterioration of exhaust gas characteristics.

That is, when the burner motor rotates, it gains inertia, and there is a response delay of about 1 to 5 seconds before the rotation level becomes stable, so the ratio of combustion air to fuel is disrupted during that time. Conventionally, this problem has been addressed by making various improvements to the combustor to improve its performance. However, when trying to improve the combustion exhaust gas characteristics and widen the range of combustion variation, as has been strongly demanded by the market recently, the structure of the combustor is affected delicately, and even a slight deviation in the above air-fuel ratio can result in yellow combustion or lift. There have been some cases in which combustion abnormalities such as misfires are likely to occur, and in worse cases, combustion abnormalities such as misfires are likely to occur, and exhaust gas characteristics are also deteriorated. In other words, it has become difficult to deal with this on the combustor side.

The present invention was made in view of the current situation, and it is an object of the present invention to enable the combustion amount to be changed without changing the air-fuel ratio.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention uses a fuel supply device that changes the amount of fuel discharged depending on the pulse state, and also supplies fuel to a control section that controls combustion air and fuel. A pulse delay changer is provided to gradually change the pulses to the device.

Effects of the present invention With the above configuration, when the combustion amount is switched, the amount of fuel discharged from the fuel supply device changes to match the change in the rotation speed of the burner motor, and the balance between combustion air and fuel is disrupted. That will no longer be the case.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

Fig. 5 is a diagram showing a schematic configuration of a fan heater, in which 1 is an outer shell, 2 is a vaporization type combustor provided inside the outer shell, and 3 is a combustor that supplies combustion air to the combustor and rotates by switching taps. burner motor whose number can be changed; 4 is a pulse pump with a built-in drive circuit 4' that supplies liquid fuel to the combustor in an amount corresponding to the frequency of the pulse signal when a specific pulse signal is input; 5 is a pulse pump that supplies fuel to the pulse pump; fuel tank to supply;
6 is a combustion tube connected to the combustor; 7 is a convection blower installed to send heat from the combustion tube into the room; 8
9 is a room temperature detection element provided to detect the room temperature, and 9 is an igniter that performs an ignition operation when starting combustion. In addition, the operation switch 10 that operates the combustion ○N10 F F
, a room temperature setting volume 11, and the like are provided in an operation section (not shown).

FIG. 2 shows a circuit that controls this fan heater, and 12 is a microcomputer that compares the signal from the room temperature detection element 8 with the set temperature, changes the tap of the burner motor 3, and outputs pulses to the pulse pump 4. Performs general combustion control such as frequency control.

1a is a commercial power source; 14 is a heater embedded in the combustor 2 for vaporizing the fuel supplied from the pulse pump 4; 15 is the combustor 2 heated by the heater 14;
A temperature detection element 16-a detects the temperature of the heater 14 according to a signal from the temperature detection element 15.
17″-a is a contact point of relay 17 that turns the burner motor 3 to ○N10FF, 18-a,
1.8-b is a contact point of the relay 18 that switches the tap when changing the rotation speed of the burner motor 3, and 19-a is a contact point of the relay 19 that turns the convection blower 7 to 0N10FF, and the relay 16 has each of these relay contacts. .17.19.18
are the output terminals RO, R1 of the microcomputer 12
.
It is connected to output terminal R5 of No. 2. Further, the igniter 9 is connected to the output terminal R4 of the microcomputer 12, and the igniter 9 with an output of % L is operated.

On the other hand, the above microcomputer includes ANl, AN2,
It has an input terminal of AN3. Each input terminal ANI
, AN2, and AN3 are for directly reading analog voltages, and are divided by appropriate resistors 23°, 24, 26, and 26, and are connected to the room temperature sensing element 8, the temperature sensing element 15, and the room temperature setting polyurethane 12, respectively. Reference numeral 27 denotes a comparison section provided in the microcomputer 12, which connects each input terminal A.
Receives signals from N1, AN2, and AN3. Reference numeral 28 denotes a non-volatile memory (hereinafter referred to as ROM) which is also built into the microcomputer 12, and which receives the signal from the comparator 27 and stores it in advance, according to a predetermined procedure, i.e., program contents, to each of the output terminals RO- 15 to output a predetermined signal. This ROM25
Reference numeral 1 designates a control unit that changes the rotational speed of the burner motor a and the oscillation frequency of the pulse pump drive circuit 4'. Reference numeral 29 is a volatile memory (hereinafter referred to as RA) which is built in the microcomputer 12 and can be freely rewritten.
M) is used to store data temporarily generated while the microcomputer 12 performs work.

In the above configuration, when the microcomputer 1o detects that the operation switch 11 is turned on, the relay 16
ONI, energize heater 14t.

When the temperature detection element 15° detects that the temperature of the combustor 2 has reached a predetermined temperature, the relays 19 and 17 are activated.
Operate ONL convection blower 7 and burner motor 3,
After a while, terminal R5 is connected to drive pulse pump 4.
simultaneously outputting a pulse signal and driving the igniter 9,
Light the ignition. At this time, when the pulse pump 4f is driven at 16Hz, the signal output from the terminal R5 is 'H〃 signal for 1ms, and then 62.5mm1fi'L''
The operation of outputting a signal will be repeated. Here, the output signal %L #%H' is the pulse pump 4
The reverse may occur depending on the circuit configuration on the side, and since the 'H' signal output period is sufficiently shorter than the %L/F signal output period, the effect on the output frequency can be ignored.

When combustion starts, the signal of the room temperature detection element 8 input from the terminal ANI and the signal of the room temperature setting volume 11 input from the terminal AN3 are compared, and if the room temperature is higher, the combustion is weak.
On the other hand, if it is low, the combustion will be switched to strong combustion. At the time of strong twisting, the contact of the relay 18 is connected to the 18-a side so that the rotation speed of the burner motor 3 becomes high, and the pulse pump 4 is connected to the 16H side.
The burner motor is assumed to operate at
It is assumed that when coil (coil) V of the relay 18 is excited so that the rotation speed of the relay 18 becomes low, the contact of the relay 18 is connected to the 18-b side, and the pulse pump 4 operates at 5 Hz.

Below, we will explain the switching of the combustion amount mentioned above.
In FIG. 2, the ANI of the microcomputer 12, A
The signals input to N2 and AN3 are compared by a comparison section 27, and a predetermined signal such as strong, weak, or off is output. Based on this signal, the plow burner motor control section 30 supplies a signal to the output terminal R3 to switch the burner motor 3 to high or low power. At the same time, the signal from the comparator section 27 is sent to the pulse delay changing section 31, which supplies a pulse signal to the output terminal R5 and drives the pulse pump via the photocoupler 20. circuit 4'
is driven to operate the pulse pump 4. This pulse delay changing section a1 is connected to the pulse generating section 32 which supplies pulses to the output terminal R5, and the target pulse for setting a strong or timing pulse (in this embodiment, as described above, the strong hold is 16 Hz, and the weak one is 5 Hz). The signal from the pulse setting section 33 is compared by the pulse comparison detection section 34, and the difference is corrected little by little by the pulse modification section 35 and fed back to the pulse generation section 32, thereby repeating cycle/I/1. Thus, the pulse generated from the pulse generator 32 is gradually brought closer to the target pulse. This will be explained in more detail using the flowchart shown in FIG.

A burner motor control routine 30a, a target pulse setting μm routine 33a, and a pulse correction routine 35a are located anywhere in the main routine.
In step a, the contact of the relay 18 is switched in order to change the rotation speed of the burner motor according to the amount of combustion, and in the target pulse setting routine 33a, the pulse frequency for strong twist firing and weak combustion which are preset in the ROM is changed. Set the pulse frequency for use in the target value area (not shown).

The target value area is an area to which a part of the RAM 29 is allocated and stores a value at which the frequency of the pulse pump 4 is finally stabilized. The pulse correction routine 35a compares the current value, which is the value of the current area (not shown) in which the pulse frequency currently being output is set in a part of the RAM 29, with the target value every second (a timer is not included). (not shown), and if different, adds or subtracts the value set in the current area by 1 so that it becomes equal to the target value, and a part of the RAM 29 adds or subtracts the value by 1.
The reciprocal of the value set in the fertilizer area is set, and when the result of subtraction by 1 results in a value less than 0, the output part outputs only one PALNU for driving the pulse pump 4.

In the above configuration, if we switch from weak combustion to strong twist firing, first, in the burner motor control routine 30a, the output of the output terminal R3 is set to 'H' and the contact of the relay 18 is connected to the 18-a side.Next, In the target pulse setting routine 33a, the pulse frequency of 18 Hz for strong twist firing, which is previously set in the ROM 28, is set in the target value area.

In the pulse correction routine 35a, 1 second is determined in step 36, and if no, step 11 is determined, and if yes, the process proceeds to step 37 in which it is determined whether the current value and the target value match. Since the combustion was weak at first, the current value is set to 5 Hz, and it is judged as no in step a7, so the current value is adjusted or subtracted in step 38.
It is corrected to 6Hz. Next, in step 39, the value of the counter to which the reciprocal of the previous current value is initialized is incremented by 1. The result of step 39 is judged in step 40, and if it is 0 or more, go to J2, if it is less than 0, a pulse output is attempted in step 41, and in step 42, a value obtained by multiplying the reciprocal of the current value of 6 Hz by an appropriate coefficient K is set in the counter. and initialize it. As the main routine is repeated several times, the above current value gradually approaches 16Hz, and when the current value reaches 16Hz, it is always judged as y@s in step 37, and by skipping step 38, the pulse output frequency becomes stable at 16Hz. do. Conversely, when switching from weak combustion to strong twist firing, set output terminal R3 to %Lp in burner motor control routine 30a and set target value f.
This can be achieved by setting it to 5 Hz.

The above situation is shown in Figure 1 - A shows the change in the rotational speed of the burner motor 3 and the frequency change of the Rohahals pump 4, with tl switching from strong to weak and t2 switching from weak to strong. There is.

In the above embodiment, the same routine is used for strong to weak and weak to strong twisting, but the value to be adjusted in step 38 or the time in step 36 may be changed for each of strong to weak and weak to strong twisting. By doing so, it becomes possible to accurately respond to subtle changes in the rotation speed of the burner motor.

Furthermore, if the value for adjusting the frequency in step 38 is not a fixed value but is given as a time function, for example, a pulse change that is more suitable for the number of revolutions of the Shivana motor as shown in FIG. 1-C can be obtained.

Effects of the Invention As described above, since the control device of the present invention gradually changes the pulse output to the fuel supply device when switching the combustion amount,
It is possible to minimize the air-fuel ratio deviation when changing the combustion diet, and it is also possible to make delicate settings according to the burner motor rotation speed, so the range of combustion changes can be expanded without deteriorating the combustion exhaust gas characteristics. This has the effect of making it possible.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a control device in an embodiment of the present invention;
Figure 2 is a block diagram of the main parts, Figure 3 is a flowchart to explain the operation, Figure 4 is a synchronization diagram, A is the rotation speed of the burner motor, C shows pulse outputs in other embodiments. FIG. 5 is a sectional view of a heater using the control device of the present invention, and FIG. 6 is a circuit diagram showing a conventional control device. 2... Combustor, 3... Combustion air supply device (burner motor), 4... Fuel supply device (pulse pump), 8... Room temperature detection element , 12...
...Control means (microcomputer), 31...
... Hals delay changing section, 32 ... Pulse generation section, 33 ... Target pulse setting section, 34 ...
. . . Pulse comparison detection section, 35 . . . Pulse correction section. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure R3R5 Drawing 3 Figure 4

Claims (5)

[Claims] (1) A combustor, a combustion air supply device that supplies combustion air to the combustor, and a combustion air supply device that is driven by a pulse input having a width greater than a certain width in order to supply fuel to the combustor, and when the input frequency of the pulse becomes low. A fuel supply device that decreases the fuel discharge amount and increases the fuel discharge amount as the input frequency increases, a room temperature detection element that detects the temperature in the heated room, and a room temperature detection element that detects the temperature of the room temperature detection element. and control means for controlling the supply amount of the fuel, and the control means gradually pulses the fuel supply device so that the supply amount of the fuel gradually changes with respect to the supply amount of the combustion air. A control device for a heating machine having a pulse delay changing section that changes the pulse delay. (2) The pulse delay changing unit compares the pulse generation unit, the target pulse setting unit, and the difference between the pulses from both at certain time intervals, and performs pulse modification to bring the pulse from the pulse generation unit closer to the target pulse. A control device for a heating machine according to claim 1, comprising: (3) The pulse correction section is configured to detect a difference in frequency or cycle of pulses from both the pulse generation section and the target pulse setting section and correct this at regular time intervals. Heater control device. (4) The heating machine control device according to claim 2, wherein the pulse correction section is configured to change the time for detecting the pulse difference from both the pulse generation section and the target pulse setting section. (5) A control device for a heater according to claim 2, wherein the pulse correction section is configured to change the pulse in accordance with a change in the rotational speed of the combustion air supply device.