JPS625546Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a combustion control device that controls the vaporization and combustion of fuel oil in a vaporizer.

Conventionally, in this type of combustion control device, when the temperature of the carburetor reaches a certain constant temperature _T1 , fuel supply is started to start the combustion operation, and then the temperature of the carburetor is maintained at approximately constant _T1 . ing.
That is, in the past, the vaporizer temperature was kept substantially constant both at the start of combustion and during combustion operation.

However, with such a device, if the ambient temperature is quite low, for example, the fuel temperature will be low at the time of ignition at the start of combustion, so ignition will start without a sufficient amount of vaporization being obtained. There was a point where a stable and good combustion start could not be achieved due to the occurrence of standing flames, red flames, etc.

This idea was devised to eliminate these drawbacks, and by raising the temperature of the carburetor at the start of combustion higher than the temperature during steady combustion, a stable and good combustion start can be achieved, and the circuit It is an object of the present invention to provide a combustion control device that has a simple and good configuration.

Hereinafter, embodiments of this invention will be described with reference to the drawings.

1 is a negative characteristic thermistor as a temperature detector for detecting the temperature of the vaporizer 2; one end of this thermistor 1 is connected to the + _Vcc terminal via a resistor 3, and also connected to the + _Vcc terminal via a resistor 4; The other end is grounded. 5 is a heater control circuit consisting of a series voltage divider circuit of resistors 6 and 7 and a first comparator 8;
The non-inverting input terminal (+) of the first comparator 8 is connected to the + _Vcc terminal via the resistor 6 and grounded via the resistor 7, and the inverting input terminal (-) is connected to the thermistor 1, the resistor 3, It is connected to the connection point Q with 4. the first comparator 8
connects its output terminal to the first relay 9 for heater control.
It is connected to the + _Vcc terminal via. In addition, the first
A protective diode 10 is connected in parallel to the relay 9 . 11 is a control circuit that prohibits the heater control circuit 5 from controlling the energization stop to the heater, and once detected, cancels the prohibition of the energization stop control, and also controls the second relay 12 for fuel oil supply control; This control circuit 11 includes a resistor 13,
14 series voltage divider circuits, a second comparator 15,
NPN type first, second and third transistors 1
6, 17, and 18. The control circuit 11 connects the non-inverting input terminal (+) of the second comparator 15 to the + _Vcc terminal via a resistor 13 and grounding it via a resistor 14, and connects the inverting input terminal (-) to the connection point. Connected to Q. A resistor 19 is connected in parallel to the resistor 14 via the second transistor 17.
The output terminal of the second comparator 15 is connected to a resistor 2.
0 to the + _Vcc terminal and resistor 2
1 to the base of the third transistor 18. The first transistor 16 is connected in parallel to the resistor 7 of the heater control circuit 5. The third transistor 18 has its collector connected to the first transistor 1 through a resistor 22.
6 and the base of the second transistor 17 via the resistor 23;
It is also connected to the + _Vcc terminal via the second relay 12. Note that a protection diode 24 is connected in parallel to the second relay 12.

The heater control circuit 5 includes a first transistor 1
6 is in the OFF state, and the thermistor 1 detects the vaporizer temperature T1 _or higher, the input level of the non-inverting input terminal (+) of the first comparator 8 is made higher than the input level of the inverting input terminal (-). The circuit constants are determined so that the output level of the first comparator 8 is set to a high level when the thermistor 1 detects a temperature lower than the temperature _T1 , and the output level of the first comparator 8 is set to a low level. .

In the control circuit 11, the second transistor 17 is in an on state, and the input level to the non-inverting input terminal (+) of the second comparator 15 is equal to that of the resistor 14.
9, the non-inverting input terminal of the second comparator 15 is activated when the thermistor 1 detects a second set temperature _{T2 or} higher which is higher than the first set temperature T1. (+) input level becomes higher than the input level of the inverting input terminal (-), the output level of the second comparator 15 becomes high level, and when thermistor 1 detects a temperature lower than temperature _T2 , the second The circuit constants are determined so that the output level of the comparator 15 becomes low level. Further, in the control circuit 11, when the second transistor 17 is in an off state and the input level to the non-inverting input terminal (+) of the second comparator 15 is determined only by the resistor 14, the thermistor 1 is When a third set temperature T3 _or higher lower than the first set temperature _T1 is detected, the input level of the non-inverting input terminal (+) of the second comparator 15 is lower than the input level of the inverting input terminal (-). When the temperature increases, the output level of the second comparator 15 is set to a high level, and when the thermistor 1 detects a temperature lower than the temperature _T3 , the circuit constants are set so that the output level of the second comparator 15 is set to a low level. ing.

When the power is turned on in such a configuration, since the temperature of the vaporizer 2 is now low, the resistance value of the thermistor 1 is large, and the resistance value of the thermistor 1 is large.
Since the input level of the inverting input terminal (-) is higher than the input level of the non-inverting input terminal (+) and the output level is low level, the first relay 9 is energized and the heater is not energized. will be started. Further, the third transistor 18 is controlled to be off, the first and second transistors 16 and 17 are turned on, and the second relay 12 is kept deenergized. In this way, the vaporizer 2 is heated by the heater and its temperature is gradually increased. and vaporizer 2
When the temperature of the thermistor 1 reaches T ₁ which is maintained during steady combustion, the resistance value of the thermistor 1 becomes considerably small and the potential of the connection point Q becomes low, but the resistor 7 is short-circuited by the first transistor 16 and the first comparator 8 Since the input level of the non-inverting input terminal (+) becomes approximately zero level, the output level of the first comparator 8 is maintained at a low level, and current is continued to be supplied to the heater. The vaporizer 2 is thus heated above the temperature _T1 . When the temperature of the vaporizer 2 reaches _T2 , the resistance value of the thermistor 1 decreases, and the input level of the inverting input terminal (-) of the second comparator 15 becomes lower than the input level of the non-inverting input terminal (+). . Thus, the output level of the second comparator 15 is inverted from low level to high level. This turns on the third transistor 18,
The second relay 12 is energized and the supply of fuel oil to the carburetor 2 is started, and the first and second transistors 16 and 17 are turned off. When the first transistor 16 is turned off, the short-circuited state of the resistor 7 is released, and the input level of the non-inverting input terminal (+) of the first comparator 8 changes to the inverting input terminal (-).
is greater than the input level. As a result, the output level of the first comparator 8 becomes high level, the first relay 9 is deenergized, and the power supply to the heater is stopped. On the other hand, when the second transistor 17 is turned off, the resistor 19 is disconnected from the resistor 14 and the second transistor 17 is turned off.
The input level of the non-inverting input terminal (+) of the second comparator 15 increases, and from then on, the input level of the second comparator 15 increases.
The output level will not be reversed from high level to low level unless the temperature of the vaporizer 2 reaches _T3 , which is lower than _T1 . In this way, the temperature of vaporizer 2 is
Fuel oil is supplied at a temperature T ₂ higher than T ₁ during steady combustion. Therefore, even when the ambient temperature is quite low and the temperature of the fuel oil is decreasing, the fuel oil is sufficiently vaporized in the vaporizer 2,
There is no risk of phenomena such as standing flames or red flames occurring during ignition, and a stable and good combustion start can be achieved.
When the temperature of the vaporizer 2 reaches _T2 , the power supply to the heater is stopped, so that the temperature of the vaporizer 2 gradually decreases. Then, when the temperature of the vaporizer 2 falls below _T1 , the first comparator 8 is inverted, the output level becomes low level, the first relay 9 is energized, and power supply to the heater is restarted. When the temperature of the vaporizer 2 reaches _T1 , the first comparator 8 is reversed and the power supply to the heater is stopped. In this way, from now on, the temperature of the vaporizer 2 is controlled by the heater control circuit 5.
is now held approximately constant at T ₁ ,
This results in steady combustion.

Also, if the temperature of the carburetor 2 drops for some reason during steady combustion operation,
At this time, when the temperature of the vaporizer 2 becomes lower than _T3 , the output level of the second comparator 15 is inverted from high level to low level, and the third transistor 18 is turned off. Thus the second relay 1
2 is deenergized and the supply of fuel oil to the carburetor 2 is stopped to ensure safety. If the temperature change of the vaporizer 2 with respect to time is shown in a graph, it will be as shown in FIG.

Further, when the output level of the second comparator 15 becomes low level, the first and second transistors 1
6 and 17 are turned on, the circuit returns to the control state at the start of combustion.

In the above embodiment, a negative characteristic thermistor is used as the temperature detector, but it is needless to say that the present invention is not limited to this.

As described in detail above, according to this invention, a heater control circuit is provided which controls to stop energizing the heater that heats the vaporizer when the temperature detector detecting the vaporizer temperature detects the first temperature. prohibiting the heater control circuit from controlling the energization to the heater until the device detects a second temperature higher than the first temperature, and once the detection is detected, prohibiting the heater control circuit from controlling the energization to the heater from stopping; Since the state is released, the temperature of the carburetor can be set higher than the temperature required during steady combustion at the time of ignition at the start of combustion.
Even when the ambient temperature is low, the vaporization of fuel oil in the carburetor can be ensured, and a stable and good combustion start can be achieved without the occurrence of standing flames or red flames.
Moreover, since only one temperature detector is used, it is possible to provide a combustion control device with a simple circuit configuration.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of this invention, Figure 2 is a circuit diagram showing an embodiment of this invention.
The figure is a graph showing temperature changes over time in the vaporizer in the same example. 1... Negative characteristic thermistor, 2... Vaporizer, 5...
... Heater control circuit, 11 ... Control circuit, 8, 15
... Comparator, 9, 12 ... Relay, 16,
17, 18...NPN type transistor.

Claims (1)

[Scope of utility model registration request] Fill a vaporizer preheated with a heater and vaporize it.
The combustion control device for ignition includes a temperature detector that detects the vaporizer temperature, a heater control circuit that controls to stop energizing the heater when the temperature detector detects a first temperature, and the temperature detector means for prohibiting the heater control circuit from controlling the energization stop to the heater until a second temperature higher than the first temperature is detected, and once detected, canceling the prohibited state of the energization stop control. A combustion control device characterized by: