JPH08232766A - Control method for ptc heater for heating carburetor - Google Patents

Abstract

PURPOSE: To provide a control method for a PTC heater for heating a carburetor ensuring the number of revolutions for cranking for an engine starting when the temperature is very low. CONSTITUTION: A PTC heater for heating a carburetor comprises a current detector 13 to energize a PTC heater 8 after the drive current of a starter motor 9 is turned OFF; and a control device 14. Or, the PTC heater comprises a rotation detector and a control device 14 to energize the PTC heater 8 when the number of revolutions of an engine exceeds a given value C. Further, the PTC heater 8 is provided with a thermoswitch to energize the PTC heater 8 at a water temperature exceeds a set temperature D and controls the PTC heater.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a PTC heater of an icing prevention device for a vaporizer.

[0002]

2. Description of the Related Art In an engine of an automobile operated in cold weather, a so-called icing phenomenon occurs in which water in intake air freezes in a mixture passage of an carburetor of the engine due to a temperature decrease due to latent heat of vaporization accompanying vaporization of gasoline fuel. You may be able to see. This icing is particularly likely to occur around the throttle valve, and if icing occurs around the throttle valve, a predetermined opening area corresponding to the opening of the throttle valve may not be obtained and the output may decrease. In order to prevent this, in some vaporizers, a heater of a positive temperature characteristic heating element (hereinafter referred to as PTC heater) is attached to heat the fuel passage of the vaporizer. As an example of this, the actual exploitation 59-57
No. 54, etc.

[0003]

However, in such a conventional device, the PTC heater is used as a heater that serves both as a heating element and a temperature controller, but is large at the initial stage of energization of the heater. It consumes power. In addition, at extremely low temperatures (for example, -15 degrees Celsius or less), this power consumption is further increased, which causes a large electric load on the battery and a large decrease in the voltage applied to the starter motor at the time of start-up. There is a problem that startability deteriorates due to a decrease in cranking speed, deterioration of ignition performance, and the like. Further, even after the engine is started, a load is applied to the engine such that the amount of power generated by the alternator increases, the engine rotation becomes unstable during warm-up, and in the worst case, engine stall occurs. It is an object of the present invention to provide a PTC heater control method for solving such a conventional problem.

[0004]

SUMMARY OF THE INVENTION The present invention provides a vaporizer with a PT.
An icing prevention device having a C heater is characterized in that the PTC heater is not energized at least during cranking rotation at the time of starting. Alternatively, in claim 1, the energization of the heater is started by detecting that the drive current of the starter motor has changed from the energized state to the stopped state. Alternatively, in claim 1, energization of the heater is started by detecting that the number of revolutions of the engine has reached a predetermined number of revolutions or more. Alternatively, in the icing prevention device including the PTC heater in the carburetor, the PTC heater is not energized when the engine temperature is extremely low. Alternatively, in claim 4, energization of the heater is started when the engine temperature detector detects an engine temperature equal to or higher than a set temperature.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention. An intake passage 2 is provided in a carburetor 1 shown in the drawing, and a throttle valve 3 and an inner venturi 4 are provided in the intake passage 2.
Is provided. A choke valve 5 is provided on the upstream side of the intake passage 2. The intake manifold 6 has a heat insulator 7 on the downstream end surface of the carburetor 1.
Is attached through. A PTC heater 8 is inserted on the vaporizer 1 side of the heat insulator 7, and a heating surface of the heater 8 is in contact with an end surface of the vaporizer 1.

2 and 3 are a block diagram and a time chart of the control circuit of the heater 8 according to the first embodiment. In the starter motor 9 in the figure, when the engine switch 10 is closed and then the starter switch 11 is closed,
Power is supplied from the power source 12 to drive the engine. Further, when the starter switch 11 is opened, the motor 9 stops.
The current detector 13 detects the intermittent drive current and turns it off.
The signal A is input to the control device 14. Further, the heater 8 has a temperature / resistance characteristic as shown in FIG. 4, and when the energization is started, the temperature rises, the electric resistance sharply increases, and the current decreases. In addition, when the temperature drops, the amount of heat generated increases to keep the temperature almost constant,
The vaporizer 1 is heated as a heater having both functions of a heating element and a temperature controller. The control device 14 receives the OFF signal A from the current detector 13, and starts the heater 8 from the power source 1 from that time.
The heater 8 is connected to the second side and controlled to start energizing the heater 8. Next, the operation will be described with a time chart. When the engine switch 10 is turned on and the starter switch 11 is further turned on, the drive current of the motor 9 starts to be energized. The engine starts and the starter switch 11 turns off.
When this is done, the drive current is turned off, and the control device 14 starts energizing the heater 8 by the OFF signal A due to this.

According to the method of the first embodiment as described above, it is possible to prevent the engine switch 10 from being turned on to energize the heater 8 before starting the engine, thereby saving unnecessary power consumption. It is possible to prevent a large electric load of the motor 9 during cranking rotation and a large electric load of the heater 8 at the initial stage of energization from being applied to the battery at the same time during the cranking period, so that a large drop in voltage during cranking rotation can be prevented. As a result, it is possible to prevent a large decrease in the cranking speed of the engine, prevent a decrease in the performance of spark ignition, and maintain good starting performance.

5 and 6 are a block diagram and a time chart of a control circuit of the heater 8 according to the second embodiment. The configurations of the starter motor 9, the starter switch 11, and the heater 8 here are the same as those of the first embodiment, and therefore their explanations are omitted. The rotation detector 15 of the engine detects the signal from the ignition coil and detects the rotation signal B.
And Further, the control device 14 receives the rotation signal B from the rotation detector 15, and the engine rotation speed is the predetermined rotation speed C.
When the speed reaches (for example, 400 rpm) or more, the heater 8 is connected to the power source 12 side to control the heater 8 to start energization. To explain the operation of this with a time chart, the starter switch 11 is turned off when the engine is stopped.
When the engine speed is N, the engine is driven by the motor 9, and after the cranking period, the complete explosion starts and the rotation starts to increase. When the engine speed reaches or exceeds a predetermined speed C set between the cranking speed and the idle speed,
The rotation signal B causes the controller 14 to start energizing the heater 8.

According to the method of the second embodiment as described above, in addition to the effects of the first embodiment, in addition to this, a predetermined number of revolutions at which the rotation is stable after the engine is completely detonated. Since the heater 8 is energized at C or higher, the heater 8 is prevented from being energized during an unstable operation time from the cranking speed to the rotation speed at which the rotation can be stably performed, and the power generation amount of the generator is reduced. The effect of preventing the engine speed from becoming unstable and the engine stall from occurring due to the increase in the engine load due to the increase is also obtained.

Further, FIGS. 7 and 8 are a block diagram and a time chart of the control circuit of the heater 8 according to the third embodiment. Thermo switch 1 to detect engine temperature
6 is arranged in the engine cooling water passage of the cylinder head. This thermo switch 16 has a set temperature D on the cryogenic side.
A cryogenic open contact 17 that opens the thermoswitch 16 at a water temperature below (for example, -15 degrees Celsius), a closed contact 18 that connects the thermoswitch 16 to the power supply 12 side at a water temperature above this set temperature D, and a high temperature. Side set temperature E (for example,
It is composed of a high temperature open contact 19 that opens the thermoswitch 16 at a water temperature of 60 degrees Celsius or higher, and a movable contact 20 that is connected to the heater 8. The closed contact 18 is connected to the engine switch 10 and the power source 12 side. Explaining this with a time chart,
When the engine cooling water temperature is equal to or lower than the set temperature D on the extremely low temperature side, the engine switch 10 is turned on, the starter switch 11 is turned on, and the water temperature does not rise during the period when the motor 9 is cranking the engine. Reference numeral 16 indicates that the movable contact 20 is on the cryogenic open contact 17 side and is in the OFF state, so that the heater 8 is not energized. When the engine is completely detonated and the operation is continued and the water temperature rises above the set temperature D on the extremely low temperature side, the thermo switch 16 moves the movable contact 2
0 is on the side of the closed contact 18 and is closed, and the heater 8 is powered by the power source 1
The heater 8 is connected to the second side to start energization. When the water temperature further rises and becomes equal to or higher than the set temperature E on the high temperature side, the thermoswitch 16 is turned off because the movable contact 20 is on the high temperature open contact 19 side, and the energization to the heater 8 is stopped.

According to the method of the third embodiment as described above, when the water temperature of the engine is equal to or lower than the set temperature D on the extremely low temperature side, energization to the heater 8 having a large electric load is stopped at the time of starting, and the battery is charged. Since such a large electric load can be reduced only to the drive current of the motor, the drop in battery voltage can be reduced, the cranking speed can be prevented from lowering, and the spark ignition performance can be prevented from lowering to improve the starting performance at extremely low temperatures. A sustainable effect is obtained. In addition to this, since the heater 8 is not energized until the water temperature rises to the set temperature D after the start, the heater is heated at an unstable rotation timing until the engine is completely exploded and the rotation is stabilized. It is possible to prevent the energization of 8 and to prevent the engine speed from becoming unstable and the engine stall from occurring due to the increase in the engine load due to the increase in the power generation amount of the generator. Further, when the engine temperature is equal to or higher than the set temperature D on the extremely low temperature side, the starting performance of the engine is good, and the heater 8 is energized to prevent the icing from occurring.

[0012]

According to the method of the present invention, since the heater is not energized at least during the cranking rotation at the time of starting, the electric load applied to the battery during the cranking rotation is reduced. However, it is possible to prevent a decrease in battery voltage, prevent a decrease in cranking rotation speed, and prevent a decrease in spark ignition performance.

Further, according to the method of the present invention, the energization of the heater is started by detecting that the drive current of the motor has changed from the energized state to the stopped state, so that the engine switch is turned on before the engine is started. The heater is prevented from being energized to save unnecessary power consumption, and the large electric load of the motor during cranking rotation and the large electric load of the heater at the initial stage of energization are simultaneously applied to the battery during the cranking period. It works to prevent this, reduce the electric load on the battery, and reduce the voltage drop. As a result, the cranking rotation speed can be prevented from lowering, the spark ignition performance can be prevented from lowering, and the starting performance can be maintained.

Further, according to the method of the present invention, the energization of the heater is started upon detecting that the engine speed reaches a predetermined speed or more, so that the same operation / effect as the above-mentioned invention can be achieved. In addition to the effect, in addition to this, it is possible to avoid energizing the heater during unstable rotation timing until the engine rises from the cranking rotation speed to the predetermined rotation speed at which it can rotate stably, and the power generation of the generator is avoided. It is possible to prevent the engine speed from becoming unstable and the engine stall from occurring due to the increase in the engine load due to the increase in the amount.

According to the method of the present invention, the heater is not energized when the engine temperature is extremely low, but normally, the humidity of the intake air is low and the water content in the intake air is low when the engine temperature is extremely low. Since icing hardly occurs, it is not necessary to energize the heater at this time.
The electric load on the battery at the time of starting can be reduced, the cranking speed can be prevented from decreasing, the performance of spark ignition can be prevented from decreasing and the starting performance can be maintained, and until the engine temperature rises to a predetermined temperature after starting. Since the heater is not energized, it is possible to avoid energizing the heater even during unstable rotation time until the engine completes explosion and the rotation stabilizes, and the engine load increases due to the increase in the power generation of the generator. This can prevent the rotation speed from becoming unstable and the engine stall from occurring.

Further, according to the method of the present invention, since energization of the heater is started by the engine temperature detector detecting the engine temperature above the set temperature, the engine temperature below the set temperature is started. In this case, there are the same actions and effects as those of the above invention. Further, when the engine temperature is equal to or higher than the set temperature, the engine startability is good, and the heater is energized to prevent icing from occurring.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment according to the present invention.

FIG. 2 is a block diagram of a heater control circuit according to the first embodiment of the present invention.

FIG. 3 is a time chart of the first embodiment according to the present invention.

FIG. 4 is a temperature / resistance characteristic diagram of a positive temperature characteristic heating element.

FIG. 5 is a block diagram of a heater control circuit according to a second embodiment of the present invention.

FIG. 6 is a time chart of the second embodiment according to the present invention.

FIG. 7 is a block diagram of a heater control circuit according to a third embodiment of the present invention.

FIG. 8 is a time chart of a third embodiment according to the present invention.

[Explanation of symbols]

 1 Vaporizer 8 PTC heater 9 Starter motor 16 Temperature detector (thermo switch) A Drive current stop signal C Predetermined rotation speed D Set temperature (very low temperature side)

Claims (5)

[Claims] 1. A method for controlling a PTC heater for heating a carburetor, characterized in that, in an icing prevention device having a PTC heater in the carburetor, the PTC heater is not energized at least during cranking rotation at the time of starting. . 2. The control of a PTC heater for heating a carburetor according to claim 1, wherein energization of the heater is started by detecting that the drive current of the starter motor has changed from an energized state to a stopped state. Method. 3. The method for controlling a PTC heater for heating a carburetor according to claim 1, wherein energization of the heater is started upon detecting that the engine speed has reached a predetermined speed or more. 4. A method for controlling a PTC heater for heating a carburetor, characterized in that, in an icing prevention device having a PTC heater in the vaporizer, the PTC heater is not energized when the engine temperature is extremely low. 5. The method for controlling a PTC heater for heating a carburetor according to claim 4, wherein energization of the heater is started when a detector for engine temperature detects an engine temperature higher than a set temperature.