JPH0654170B2 - Vaporizer temperature controller - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature control device for a vaporizer of liquid fuel, which is applied to a combustor or the like.

[Prior Art] FIG. 8 is an overall configuration diagram showing a conventional temperature controller for a vaporizer.

In the figure, (1) is an oil tank, (2) is an electromagnetic pump for supplying kerosene from this oil tank (1) to an evaporation chamber (5) inside a vaporizer (4) through an oil pipe (3), ( 6)
Is a heater for heating the vaporizer (4), (7) is a temperature sensor for detecting the temperature of the vaporizer (4), (8) is the temperature of the vaporizer (4) detected by the temperature sensor (7) and A calculation means (9) for calculating a deviation from an optimum target temperature for vaporizing the set kerosene, (9) determines how many seconds the heater (6) is energized during a fixed time based on the value of the deviation. A duty ratio determining means (10) is a duty controlling means for controlling power feeding to the heater (6) according to the duty ratio determined by the duty ratio determining means (9), and the carburetor (4) is heated to a target temperature (about 250 ° C.). The temperature is controlled so as to be maintained at ~ 300 ° C.

(11) is a nozzle hole through which the vaporized gas vaporized in the vaporization chamber (5) is jetted, (12) is a needle for opening and closing the nozzle hole (11), and (13) is attached facing the nozzle hole (11). The burner is provided with a spark plug (14) for igniting the vaporized gas and a frame rod (15) for detecting the ion current of the flame.

Next, the operation will be described. First, the operation switch (not shown)
When is turned on, preheating of the carburetor (4) is started, and heating is performed by continuously energizing the heater (6) with an AC full wave (duty factor 100%).

The temperature of the carburetor (4) is detected by the temperature sensor (7), and it is judged by the calculating means (8) whether or not this temperature has reached a predetermined level of ignitable ignition temperature.

When the detected temperature reaches the ignition temperature, the ignition operation is performed, the electromagnetic pump (2) operates, and kerosene is supplied from the oil tank (1) to the vaporization chamber (5) through the oil pipe (3). Are heated at the same time to become vaporized gas, and the nozzle hole (1
The air is ejected from 1), and at that time, the primary air that acts as combustion air at the time of ejection is sucked from the surroundings and enters the burner (13) as an air-fuel mixture.

A spark plug (14) is attached to the upper portion of the burner (13) to start discharge at the same time as preheating is completed, and the mixture is ignited by sparks at the time of discharge.

After ignition, when the flame ion current detected by the flame rod (15) exceeds a certain value, the spark plug (1
Stop the discharge in 4).

The temperature of the carburetor (4) during combustion is constantly detected by the temperature sensor (7) and input to the computing means (8). The calculation means (8) calculates a deviation between this temperature and a preset target temperature that is optimal for vaporizing kerosene, and sends the calculated value to the duty ratio determination means (9). The energization rate determining means (9) determines the energization rate to the heater based on the value of the deviation, and determines how many seconds to energize the heater within a fixed time.

FIG. 9 shows an example of the relationship between the deviation from the target temperature and the heater energization rate. For example, if the temperature of the carburetor (4) reaches the target temperature and is saturated when the heater (6) has a duty ratio of 40%, the duty ratio of 40 when the deviation is zero.
%, The duty factor is increased when the temperature of the carburetor (4) is lower than the target temperature, and decreased when the temperature is high.

An example of the relationship between the energization rate and the energization time to the heater (6) is as shown in Fig. 10. If the energization period is 10 seconds, the maximum power of the AC full wave is applied for 4 seconds. Seconds off. The energization rate is determined every 10 seconds based on the deviation from the target temperature, and the energization control means (10) controls the heater (6).
Is turned on and off to keep the temperature of the vaporizer (4) substantially constant.

[Problems to be Solved by the Invention] Since the conventional temperature controller for the carburetor is configured as described above, the heater (6) is turned on and off as shown in FIG. The surface temperature changes greatly,
Since the temperature ripple of the vaporizer (4) becomes large, the fluctuation of the internal pressure of the vaporization chamber (5) becomes large.

The internal pressure of the vaporization chamber (5) rises as the temperature of the vaporizer (4) rises, and as a result, the amount of kerosene supplied by the electromagnetic pump (2) decreases or the vaporization gas from the nozzle hole (11) decreases. The noise when ejecting the vehicle becomes louder and the operating noise becomes louder. Further, since the temperature ripple of the vaporizer is large, there is a risk that the vaporizer is damaged by thermal stress.

Although the temperature ripple of the carburetor (4) can be reduced by shortening the cycle of energizing the heater, the heater (6)
The period of fluctuation of the power supply voltage caused by turning on and off of the power is shortened, and the flicker often appears remarkably when the lighting equipment and the like are used at the same time.

Further, if the power capacity of the heater (6) is reduced or a half-wave rectified voltage is applied to reduce power consumption, the temperature ripple of the carburetor (4) can be reduced, but the preheating time becomes long. Or when the power supply voltage drops, 100
There were many problems such that the capacity was insufficient and the temperature of the carburetor (4) dropped even when the power was turned on.

The present invention has been made to solve such a problem, and the temperature ripple of the carburetor is small and the operating noise is reduced without shortening the energization cycle to the heater or reducing the electric power capacity of the heater. An object is to provide a low-level vaporizer temperature control device.

[Means for Solving Problems] A temperature control device for a carburetor according to the present invention includes a calculation means for calculating a deviation between the temperature of the carburetor detected by a temperature sensor and a preset target temperature, and A duty ratio determining means for determining a duty ratio to the heater based on the deviation, a determining means for determining a power feeding form to the heater based on the duty ratio determined by the duty ratio determining means, and a heater by the determination means. It has a full-wave and half-wave alternating energization control means and a half-wave energization control means for controlling the energization to.

[Operation] In the temperature control device according to the present invention, the half-wave energization control means operates when the energization rate is 50% or less so that the heater is energized to the half-wave rectified voltage, and when the energization rate exceeds 50%, the full-wave rectification voltage is applied. Since the half-wave and half-wave alternate energization control means operates to alternately apply the AC full-wave voltage and the half-wave rectified voltage to the heater, the temperature ripple of the carburetor is reduced and the operating noise is reduced.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 in which the same parts as those in FIG. 8 are designated by the same reference numerals, (16) is a judging means for judging whether the duty ratio determined by the duty ratio determining means (9) is larger or smaller than 50%,
(17) has a duty ratio of 50 due to the determination means (16).
Is a half-wave energization control means that operates when it is determined to be less than or equal to%, applies a half-wave rectified voltage to the heater (6), and turns it on and off. (18) is a full-wave and half-wave alternating energization control means that operates when the energization rate exceeds 50%, and alternately applies the AC full-wave voltage and the half-wave rectified voltage to the heater (6).

FIG. 2 is an electric circuit diagram of the embodiment of FIG. 1, in which a thermistor is used for the temperature sensor (7), and a DC voltage is divided by a resistor (19) connected in series with the thermistor,
It is converted into a digital amount through the AD conversion circuit (20) and input to the microcomputer (21).

The microcomputer (21) has an input circuit (21
a), a CPU (21b), a memory (21c), and an output circuit (21d), and processes the functions of the arithmetic means (8), the duty factor determining means (9), and the determining means (16).

(22) is a power supply transformer for stepping down the voltage of the commercial power supply (23), (24) is a diode bridge for full-wave rectifying the secondary voltage of the current transformer (22), and (25) is three for making a 1V power supply. Terminal regulator (IC), (26),
(27) and (28) are a rectifying / smoothing diode and an electrolytic capacitor.

(29) is a triac that opens and closes the energization path of the heater (6), and (30) is a phototriac coupler that opens and closes the energization path of the gate current of the triac (29), and current flows through the LED (30a) on the secondary side. Triac (2
9) is ignited.

(31) and (32) are transistors, and a current flows through the LED (30a) only when they are turned on at the same time. The base of the transistor (31) is connected to the output circuit (21d) of the microcomputer and turned on by the signal A.
The base of the transistor (32) is connected to one side of the diode bridge (24) and the collector of the transistor (33) whose base is connected to the output circuit (21d) of the microcomputer, and the negative half of the commercial power supply (23). It is turned on when the transistor (33) is turned on in a cycle or the output of the signal B. (34) to (39) are current limiting resistors.

When only the signal A is output, the triac (29) is turned on only for the half cycle of the commercial power source (23), and the half-wave rectified voltage is applied to the heater (6). When the signals A and B are output at the same time, the triac (29) is always turned on and the AC full-wave voltage is applied to the heater (6).

Next, the operation of the present embodiment configured as described above will be described with reference to the control flowchart of FIG.

First, when the operation switch (not shown) is turned on (step 3-1), preheating of the carburetor (4) is started, signals A and B are output from the input circuit (21d), and the heater (6) is energized. Full-wave energization at a rate of 100% is performed, and heating is performed (step 3-2).

The temperature of the vaporizer (4) is detected by the temperature sensor (7), digitized by the AD conversion circuit (20), and then input to the CPU (21b) via the input circuit (21a).

The CPU (21b) determines whether or not the temperature of the temperature sensor (7) has reached the ignition temperature (about 200 ° C.) (step 3-3), and if it reaches the ignition temperature, shifts to the ignition operation. (Step 3-4).

In the ignition operation, the electromagnetic pump (2) operates and kerosene is supplied into the vaporization chamber (5) to become vaporized gas. The vaporized gas enters the burner (13) through the nozzle hole (11),
It is ignited by the discharge of the spark plug (14). When the ignition operation is completed, the process proceeds to combustion control (step 3-5),
The flame condition is monitored by the flame ionic current flowing through the flame lot (15).

During combustion, the temperature of the vaporizer (4) needs to be kept substantially constant, so the temperature of the vaporizer is always measured by the temperature sensor (7) (step 3-6). Vaporizer temperature is AD
It is digitized by the conversion circuit (20) and the CPU (2
1b) is input. In the CPU (21b), the target temperature (250 ° C to 300 ° C) optimum for vaporizing the kerosene previously stored in the vaporizer measured temperature and methyl (21c)
And the deviation is calculated (step 3-
7). Based on the value of this deviation, the energization rate to the heater (6) is determined so that the temperature of the carburetor (4) approaches the target temperature (step 3-8).

Next, the determining means in the CPU (21b) determines whether or not the determined heater energization rate is 50% or less (step 3-9). When it is 50% or less, the signal from the output circuit (21d) is determined. B is turned off (step 3-10) and the signal A is turned on and off to apply a half-wave rectified voltage to the heater (6), and the temperature of the carburetor (4) is controlled by turning on and off ( Step 3-11).

When the heater energization rate exceeds 50%, the signal B is turned on or off (step 3-13), and the signal A is turned on so that the heater (6) is supplied with the AC full-wave voltage (when the signal B is on). The wave rectified voltage (when the signal B is off) is similarly controlled by being alternately applied (step 3-13).

The energization rate of the heater (6) is determined by how many seconds the heater is energized, for example, within 10 seconds during a fixed time. For example, when energizing the heater for 6 seconds with an AC full-wave voltage,
The heater energization rate is 60%, and the half-wave rectification voltage is 6
When energizing for 2 seconds, the heater energization rate becomes 1/2 and 30
%become.

FIG. 4 shows an example of the relationship between the heater energization rate and the deviation between the temperature of the carburetor (4) and the target temperature in the present embodiment. Similar to the conventional example, this relationship is set so that the heater energization rate is 40% when the deviation from the target temperature is 0. The energization mode of the heater (6) is a half-wave rectified voltage when the heater energization rate is 50% or less, and an alternating full-wave voltage and a half-wave rectified voltage when the heater energization rate exceeds 50%.

FIG. 5 and FIG. 6 are explanatory diagrams showing examples of the heater energization ratio in FIG. When the heater energization rate is 40%, the half-wave rectified voltage is turned on for 8 seconds as shown in FIG.
Repeatedly off for 2 seconds. The upper limit of the energization with the half-wave rectified voltage is 50% of the heater energization rate even with continuous energization.
Therefore, for example, when the power supply voltage drops, the heater energization rate is 5
When the temperature of the carburetor (4) does not reach the target temperature even at 0%, the heater energization rate is increased to 60%, and as shown in FIG. Repeatedly off for 8 seconds.

FIG. 7 shows changes in the carburetor temperature, the carburetor internal pressure, the kerosene supply amount, and the operation noise when the heater is energized by half-wave rectification in the present embodiment.

When the heater (6) is energized with a half-wave rectified voltage, the electric power during energization is halved compared to the energization with an AC full-wave voltage, so the carburetor (4) generated by turning it on and off Ripple becomes small. Further, when the heater energization rate is 40% and compared with the conventional example, the ON time is extended and the OFF time is shortened, so that the temperature ripple of the carburetor (4) is further reduced.

When the temperature ripple of the carburetor (4) becomes small, the change of the internal pressure of the carburetor (5) and the change of the kerosene supply amount become small, the operating noise also decreases, and the thermal stress applied to the carburetor (4) also decreases. Therefore, damage such as damage to the carburetor is reduced,
A carburetor with high reliability and long life can be obtained.

Further, during preheating or when the temperature of the carburetor (4) is low, the heater (6) is energized by alternating full-wave energization, or alternating full-wave energization and half-wave rectifying energization. The temperature of (4) can be quickly reached to the target temperature, and the preheating time of the vaporizer (4) does not become long. Even when the heater energization rate exceeds 50%, the temperature ripple of the carburetor is smaller than that of the conventional example of turning on and off the AC full-wave voltage because of full-wave and half-wave alternating energization.

As described above, according to the present invention, the half-wave rectified voltage is applied to the heater when the energization rate of the heater is smaller than the set value, and when the energization rate of the heater is smaller than the set value, the alternating current is applied. Since the full-wave voltage and the half-wave rectified voltage are applied alternately to control the temperature of the carburetor to a substantially constant value, the temperature ripple of the carburetor is reduced, the operating noise is low, and the target temperature is reached. There is an effect that it is possible to obtain a highly reliable carburetor capable of rapidly increasing the temperature.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a temperature control device for a vaporizer according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram thereof, FIG. 3 is a control flowchart showing its operation, and FIGS.
FIG. 8 is an explanatory diagram thereof, FIG. 8 is an overall configuration diagram showing a conventional temperature control device for a vaporizer, and FIGS. 9 to 11 are explanatory diagrams thereof. In the figure, (4) is a vaporizer, (6) is a heater, and (7)
Is a temperature sensor, (8) is a calculation means, (9) is a duty factor determination means, (16) is a determination means, (17) is a half-wave energization control means, and (18) is a full-wave half-wave alternating energization control means. is there. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A vaporizer for vaporizing liquid fuel, a heater for heating the vaporizer, a temperature sensor for detecting the temperature of the vaporizer, and a temperature of the vaporizer detected by the temperature sensor and preset. Calculating means for calculating the deviation from the target temperature, duty ratio determining means for determining the duration of energization to the heater during a certain time based on the value of the deviation, and duty ratio determined by the duty ratio determining means in advance. Determination means for comparing the magnitude with a set value to determine, half-wave energization control means for applying a half-wave rectified voltage to the heater when the energization rate is smaller than the set value, and the energization rate for the setting A temperature control device for a carburetor, comprising: a full-wave half-wave alternating energization control means for alternately applying a half-wave rectified voltage and an AC full-wave voltage when the value is larger than the value.