JPS61202013A - Controlling device for heater of evaporator in kerosene stove of evaporation type - Google Patents

Abstract

PURPOSE:To lower the manufacturing cost of the titled stove by miniaturizing the size of a radiator in which a transistor switching element to control the supply of electric power to the heater of an evaporator is installed, by providing a power-supply stopping means which controls to stop supplying of power to the heater of an evaporator by forcibly turning OFF the transistor switching element, when counting time by an on time counter exceeds the allowable maximum continuous energizing time which is determined based on the predetermined maximum allowable temperature of a transistor switching element. CONSTITUTION:The size of a radiator 46 is determined in relation to the allowable maximum continuous energizing time, the allowable minimum continuous deenergizing time, and the allowable maximum temperature of a thyristor 22. By this method, the size of a radiator 46 is enabled to be determined at the minimum, and the circuit base board can be miniaturized as well, and manufacturing cost can be decreased. Besides, if the thyristor 22 is energized for the while longer than the allowable maximum continuous energizing time due to abnormal condition of a negative thermistor 17 or wire disconnection, the thyristor 22 is immediately turned OFF to stop supplying of power to a heater 14, and flames are extinguished. In such a manner the thyristor 22 is prevented from being abnormally overheated, for the purpose of preventing it from being broken as the result.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vaporizer heater control device for a vaporizing kerosene stove.

[Technical background of the invention] A vaporizing oil stove is equipped with a vaporizer that vaporizes oil.
Oil supplied from an oil tank is vaporized in a vaporizer and sent to a burner along with combustion air for combustion. The vaporizer used in such a stove has a vaporizer heater embedded therein, and is heated by the vaporizer heater.

Conventionally, this vaporizer heater was controlled by detecting the temperature of the vaporizer with a temperature detection element, and when the detected temperature was lower than a preset vaporizer temperature T'C as shown in FIG. This is done by turning on the inserted bidirectional 3 terminal thyristor to turn on the heater, and when T'C is exceeded, turning off the bidirectional 3 terminal thyristor to turn off the heater. Ta.

[Problems with the Background Art] The thyristor 1 used to control such a heater generates a large amount of heat because it controls a relatively large current. There is. If we look at the temperature state of the thyristor 1, we can see a in Fig. 9.
As shown in the figure, during preheating, the temperature is high to some extent because it is turned on for a certain continuous period of time to conduct electricity, but after the temperature of the vaporizer reaches the set temperature T'C, that temperature T'C
Since the ON and OFF operations are repeated in a relatively short cycle based on , the temperature of the thyristor becomes stable within a temperature range as shown in FIG. 9b. However, if some abnormality occurs, such as an abnormality in the operation of the temperature detection element, and the on time of the thyristor 1 becomes longer and the off time becomes shorter, regardless of the temperature state of the vaporizer, as shown in C in FIG. The temperature of thyristor 1 rises. In addition, if the temperature detection element always fails in the direction of detecting a low temperature state, then the thyristor 1 will be in the ON state continuously, so the temperature of the thyristor 1 will decrease as shown by the dotted line d in Fig. 9. It will rise even more rapidly.

Therefore, conventionally, a large heat sink 2 has been used to prevent the temperature of the thyristor from exceeding the maximum allowable temperature even if such a situation occurs. For this reason, in the past, a large circuit board had to be used, and therefore the circuit section could not be made smaller, and the cost of the radiator used was high.

[Purpose of the Invention] This invention was made to solve such problems, and it is possible to reduce the size of the heat sink to which the semiconductor switching element that controls the energization of the vaporizer heater is attached, and therefore to reduce the size of the circuit board used. An object of the present invention is to provide a vaporizer heater control device for a vaporizing kerosene stove, which is capable of reducing costs and reducing costs.

[Summary of the Invention] The present invention includes a vaporizer heater that heats a vaporizer that vaporizes oil supplied to a burner, and a vaporizer heater that is inserted in series between the vaporizer heater and a power source, and that is connected to the vaporizer heater. A semiconductor switching element that controls energization, a temperature detection element that detects the temperature of the vaporizer, and when this temperature detection element detects a temperature below a preset temperature, turns on the semiconductor switching element, and when the temperature detection element detects a temperature higher than the predetermined temperature. an energization control means that turns off the semiconductor switching element when detected; an on-time counter that counts the time during which the semiconductor switching element is turned on by the energization control means; and a semiconductor switching element in which the count time of the on-time counter is set in advance. and an energization stop control means for forcibly turning off the semiconductor switching element to stop the energization to the vaporizer heater when the maximum allowable continuous energization time set based on the maximum allowable temperature of the semiconductor switching element is exceeded. When continuous energization of an element exceeds the maximum permissible continuous energization time set based on the maximum permissible temperature of the element, the element is forcibly turned off to prevent further temperature rise.

[Embodiments of the invention] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an oil stove, in which oil in an oil tank 11 is sucked up by an electromagnetic pump 12 and supplied to a vaporizer 13. The vaporizer 13 has a vaporizer heater 14 embedded therein, and is heated by the vaporizer heater 14 to vaporize the supplied oil, which is then supplied to the burner 16 through two nozzles 15 . The temperature of the vaporizer 13 is detected by a negative characteristic thermistor 17 as a temperature detection element.

Figure 2 shows the control circuit for the vaporizer heater 14, and shows the AC power supply 21.
The vaporizer heater 14 is connected to the carburetor heater 14 through a bidirectional three-terminal thyristor 22, which is a semiconductor switching element, in series.

Further, the primary winding of a transformer 23 is connected to the AC power source 21. The secondary winding of the transformer 23 is connected to the input terminal of a diode bridge circuit 24 for high wave rectification and the input terminal of a full wave rectifier circuit including diodes 25 and 26. A smoothing capacitor 27 is connected to the output terminal of the diode bridge circuit 24, and a first NPN transistor 28 and a resistor 2 are connected to the smoothing capacitor 27.
The primary winding of the pulse transformer 30 is connected through 9 in series. The secondary winding of the pulse transformer 30 is connected between the gate and terminal of the thyristor 22 via a diode 31. Note that a surge absorbing diode 32 is connected in parallel to the primary winding of the pulse transformer 30, and a resistor 33 is connected between the base and emitter of the first transistor 28. Further, a first constant voltage diode 35 is connected in parallel to the smoothing capacitor 27 via the collector and base of a second transistor 34 of NPN type. Note that a resistor 45 is connected between the collector and base of the second transistor 34. A series circuit of a second voltage regulator diode 36 and a resistor 37 is connected in parallel to a series circuit of the emitter/base of the second transistor 34 and the first voltage regulator diode 35 . A series circuit of the negative characteristic thermistor 17 and a resistor 38 is connected in parallel to the second constant voltage diode 36. Note that +Vc voltage is output from the emitter of the second transistor 34.

A series circuit of resistors 39.40 is connected to the output terminal of the full-wave rectifier circuit consisting of the diodes 25.26, and the resistor 3
9. Connect the connection point of 40 to the third NPN transistor 41
is connected to the base of

The third transistor 41 has a resistor 42 connected to the +Vc voltage source.
Its collector and emitter are connected through.

Further, a microcomputer 43 is connected to the +■0 voltage source. The collector of the third transistor 41 is connected to the input terminal Io of the microcomputer 43, and the thermistor 17 and the resistor 3 are connected to the input terminal 11.
8, the anode of the second voltage regulator diode 36 is connected to the input terminal VH, and the output terminal O
The base of the first transistor 28 is connected to the terminal o through a resistor 44.

The bidirectional three-terminal thyristor 22 is mounted on a heat sink 46 as shown in FIG.

The microcomputer 43 includes a CPU (central processing unit), ROM (read only memory), and RAM.
(random access memory), an I10 port with an A/D converter, a reference clock generator, etc.
The CPU controls the RAM and 10 ports based on program data in the ROM. As shown in FIG. 4, the RAM includes an on-time counter T1 that counts the on-time of the heater, an off-time counter CT2 that counts the off-time of the heater, a cycle timer CY that counts a preset reference time,
A first time memory TM1 stores a count value MO corresponding to the maximum allowable continuous energization time set based on the maximum allowable temperature of the thyristor 22, and a count value M1 corresponding to the allowable minimum continuous energization time of the heater. A second time memory TM2 and the like are provided.

The CPU of the microcomputer 43 performs program control shown in FIG. First, on-time counter CT
1 and clear the on time. Also, the off-time counter CT2 is reset to clear the off-time.

Subsequently, it is determined whether the temperature of the vaporizer 13 is below its holding temperature T° C. by inputting the input terminal 1.

If the temperature is below T° C., a pulse signal is output to the output terminal 00 to control the heater on, and reset the off time counter CT2. Then cycle timer CY=
Determine whether it is 1 or not. If it is CY-1, it is determined that the reference time has elapsed, the on-time counter CT1 is incremented by +1, and the cycle timer CY is cleared to zero. Also, if CY=O, this process is passed. Subsequently, it is determined whether the on-time count 1 of the on-time counter CTr is larger than the count value Mo stored in the first time memory TM1. If the count value Mo or less, the routine returns to determining the temperature of the vaporizer 13. If it is larger than the count value Mo, it is determined that there is an abnormality, and the output of the pulse signal to the output terminal 00 is forcibly prohibited, and control is performed to extinguish the smoke.

In addition, when determining the temperature of the vaporizer 13 that the temperature of the vaporizer 13 exceeds T°C, the output terminal 0
(The output of the pulse signal to l is stopped, the heater is turned off, and the on-time counter CTI is reset. Then, it is determined whether the cycle timer CY=1.C
If Y=1, it is determined that the reference time has elapsed, the off-time counter CT2 is incremented by +1, and the cycle timer CY is cleared to zero. Moreover, if CY=O, this process is bused. Next, the temperature of the vaporizer 13 is determined by the input from the input terminal ■1 again, and when it is determined that the temperature of the vaporizer 13 still exceeds T'C, the heater is again controlled to turn off and the on-time counter CT1 is reset. control,
The determination of the cycle timer CY and the temperature of the vaporizer 13 are repeated.

When it is determined in this process that the temperature of the vaporizer 13 has become below T''C, it is then determined whether the off-time count value of the off-time counter CT2 is greater than the count value M1 stored in the second time memory TM2. Then, if it is larger than the count value M1, the routine returns to the heater ON control.If the count value is less than the count value M1, it is determined that there is an abnormality and the stove is extinguished without controlling the heater ON. .

In the embodiment of the present invention having such a configuration, the diode 2
A high wave rectified waveform is outputted to the anode of 5.26, thereby turning off the third transistor 41 at approximately zero volts of the gold waveform.

Thus, the zero-cross detection signal is input to the input terminal In of the microcomputer 43. On the other hand, the voltage across the second voltage regulator diode 36 is input as a reference voltage for A/D conversion to the input terminal VR of the microcomputer 43, and the voltage across the negative characteristic thermistor 17 is input to the input terminal 11. be done. Thereby, the microcomputer 43 determines the temperature state of the vaporizer 13 from the ratio of the input voltage to the input terminal VR and the input voltage to the input terminal 1. If the temperature of the vaporizer 13 is below the holding temperature T'C, a pulse signal synchronized with the zero-cross detection signal input to the input terminal Io is output to the output terminal Oa. In this way, the first transistor 28 is turned on at the timing when the AC waveform crosses zero, and thereby the pulse transformer 3
A pulse voltage is generated in the secondary winding of 0, and the thyristor 22 is turned on. In this way, the thyristor 22 performs a zero-cross switching operation at the timing when the AC waveform crosses zero, and controls the energization of the vaporizer heater 14.

When energization to the vaporizer heater 14 is started, the off-time counter CT2 is reset, and the on-time counter CT1 counts the number of times the cycle timer CY counts the reference time. Then, before this count value exceeds the count value Mo of the first time memory TMI, the vaporizer 1
When it is determined that the temperature of the transistor 3 exceeds T° C., the output of the pulse signal from the output terminal Oo is stopped, and the first transistor 28 is kept in an off state. However, thyristor 22
is turned off in the next half cycle, and the supply of electricity to the vaporizer heater 14 is stopped.

Then, the on-time counter C1 is reset, and the off-time counter C2 counts the number of times the cycle timer CY counts the reference time. When this count value exceeds the count value M1 of the second time memory TM2 and the temperature of the vaporizer 13 becomes less than T''CC, a pulse signal is outputted from the output terminal OO again and the thyristor 22
is operated by zero-cross switching, and the vaporizer heater 14
energization is performed. Looking at the temperature state of the thyristor 22 during such normal operation, during the first preheating, the temperature of the vaporizer 13 reaches the temperature T'C from a low temperature state as shown in 'a' in Fig. 6. Therefore, the thyristor 22 is turned on for a relatively long time, and the temperature of the thyristor 22 rises to some extent. However, this temperature rise is considerably lower than the maximum permissible temperature. Thereafter, the thyristor 22 turns on and off repeatedly in a relatively short period of time in response to changes in the temperature of the vaporizer 13, so that the temperature of the thyristor 22 is maintained at a low state as shown in FIG. 6b. In this case, the reason why the temperature is slightly higher than that of the conventional thyristor temperature g/b) of the ninth section is that it is the heat sink 4 compared to the conventional one.
This is because 6 is made smaller.

Furthermore, even if an abnormality occurs in the temperature characteristics of the negative characteristic thermistor 17, the count value of the on-time counter CTI corresponding to the on-operation time of the thyristor 220 is stored in the first time memory TfVh.
is less than the count value M(l) and the count value of the off-time counter CT2 corresponding to the off-operation time of the thyristor 22 is greater than the count value M1 of the second time memory TM2, the temperature of the thyristor 22 is as shown in FIG. It changes as shown in C.The size of the heat radiator 46 can be determined so that the maximum temperature at this time is equal to or lower than the maximum allowable temperature of the thyristor 22.In this way, the maximum allowable continuous energization time of the thyristor 22 can be determined. Since the size of the heat radiator 46 can be determined based on the relationship between the allowable minimum continuous non-energizing time and the maximum allowable temperature, the size of the heat radiator 46 can be set to the minimum and can be made considerably smaller than the conventional one. The valve circuit board can also be made smaller, and costs can be reduced.

Furthermore, if the thyristor 22 is energized for longer than the allowable maximum continuous energization time due to abnormal characteristics or disconnection of the negative characteristic thermistor 17, in this case, the thyristor 22
2 is immediately turned off, power supply to the heater 14 is stopped, and the fire is extinguished.

In this way, the thyristor 22 is prevented from being abnormally heated,
To prevent the thyristor 22 from being destroyed.

Furthermore, if the thyristor 22 is turned off for a period shorter than the allowable minimum continuous de-energization time, the thyristor 22 is then kept in the off state and the fire is extinguished. In this way, the thyristor 22 is prevented from being abnormally heated due to insufficient cooling time, and the thyristor 22 is prevented from being destroyed.

In the above embodiment, even if the off time of the thyristor is shorter than the allowable minimum continuous de-energization time, the vaporizer heater 14 is controlled to be turned off to perform a fire extinguishing operation, but the present invention is not necessarily limited to this. Alternatively, the extinguishing operation may be performed by controlling the vaporizer heater 14 to turn off only when the on-operation time of the thyristor is longer than the maximum allowable continuous energization time.

Further, in the embodiments described above, a negative characteristic thermistor was used as the temperature detecting element, but it is needless to say that the present invention is not limited to this. Furthermore, although a bidirectional three-terminal thyristor was used as the semiconductor switching element in the above embodiment, it is needless to say that the present invention is not limited to this.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to downsize the radiator to which the semiconductor switching element for controlling the energization of the vaporizer heater is attached, and therefore the circuit board used can be downsized and costs can be reduced. It is possible to provide a vaporizer heater control device for a vaporizer type kerosene stove that can achieve the following goals.

[Brief explanation of the drawing]

Figures 1 to 6 show embodiments of this invention.
Figure 2 is a schematic diagram of a vaporizing kerosene stove, Figure 2 is a control circuit diagram of a vaporizer heater, Figure 3 is a perspective view of a bidirectional 3-terminal thyristor attached to a radiator, and Figure 4 is a micro A diagram showing the main memory configuration of the RAM used in the computer, Figure 5 is a flowchart showing heater control by the CPLJ of the microcomputer, Figure 6 is a graph showing the change characteristics of thyristor temperature, and Figures 7 to 9. Figure 7 shows a flowchart showing heater control, Figure 8 is a perspective view showing a bidirectional three-terminal thyristor attached to a heat sink, and Figure 9 shows the change characteristics of thyristor temperature. This is a graph showing. 13... vaporizer, 14... vaporizer heater, 16...
- Burner, 17... Negative characteristic thermistor (temperature detection element), 22... Bidirectional three-terminal thyristor (semiconductor switching element), 28... First transistor, 30
...Pulse transformer, 43...Microcomputer, 46...Radiator, CT1...On time counter, CY...Cycle timer, TMI...First time memory.

Claims (1)

[Claims] a vaporizer heater that heats a vaporizer that vaporizes oil supplied to the burner; a semiconductor switching element that is inserted in series between the vaporizer heater and a power source and controls energization to the vaporizer heater; A temperature detection element detects the temperature of the vaporizer, and when this temperature detection element detects a temperature below a preset predetermined temperature, it turns on the semiconductor switching element, and when it detects a temperature higher than the predetermined temperature, it turns on the semiconductor switching element. energization control means that operates off;
an on-time counter that counts the on-operation time of the semiconductor switching element by the energization control means; and an on-time counter that counts the on-operation time of the semiconductor switching element by the energization control means; A vaporizer heater for a vaporizing kerosene stove, characterized in that it is provided with an energization stop control means for forcibly turning off the semiconductor switching element to control the energization to the vaporizer heater to be stopped when the energization time is exceeded. Control device.