JPS6025629B2 - Diesel engine preheating control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat control device for a diesel engine equipped with a globe lug. This invention relates to a child heat control device for a diesel engine that controls the amount of electricity and keeps the temperature of a globe lug within a certain range.

Diesel engines are equipped with a globe lug as a heating device to facilitate smooth starting.
The method used is to energize the globe lug with about 3M sand to heat it up, and then turn the starter to ignite and start the engine.

Conventionally, the power supply to the globe lug was stopped after the engine was started, so the preheating device did not contribute to ignition or combustion after the engine was started. However, in diesel engines, when the combustion chamber temperature is low, such as when idling immediately after startup, irregular combustion tends to occur, and unstable conditions such as increased combustion blue and vibration due to ignition delay are likely to occur, and the exhaust gas is also unstable. Harmful ingredients tend to increase.

For this reason, a device has been proposed that uses a temperature sensor or the like to energize the glove lug when necessary even after the engine has started, but since the temperature sensor is built into the glove lug, the structure is complicated and the cost is high. . The present invention does not require difficult work such as incorporating a temperature sensor into the glove lug, and uses a glove lug with positive resistance-temperature characteristics, and detects changes in the resistance of the glove lug before and after starting the diesel engine. In this method, it is possible to reduce the noise and vibration of a diesel engine and purify the exhaust gas, and to prevent wire breakage due to overheating of the globe lug.
It is an object of the present invention to provide a child heat control device that is easy to install and is low cost.

The present invention relates to a group having positive resistance temperature characteristics.

- A detection resistor and a switching element connected in series between the plug, the switch and the globe lug, and a comparator AI connected in parallel to the detection resistor to detect the potential difference across the detection resistor and compare it with a reference potential. , and a rectangular wave oscillator having a comparator A2 and a capacitor CI charged by the output thereof, and whose duty ratio is controlled by the output of the comparator AI, and the output of the rectangular wave oscillator turns on the switching element. The main feature of this invention is that it consists of a control circuit that turns off the power.The present invention will now be described with reference to embodiments shown in the drawings. In FIG. 1, V is the battery of the diesel engine, S is the switch, and P is the glove lug attached to the engine, which has a positive resistance temperature characteristic in which the resistance value increases as the temperature rises.

Rs and 1 are a detection resistor and a switching element connected in series between the switch S and the globe lug P, and 2 is connected in parallel to the detection resistor Rs to detect the potential difference across the detection resistor and convert it to a reference potential. A comparator for comparison; 3 is a switching element that opens and closes with the output of comparator 2 to control the oscillator; 4 is a rectangular wave that operates with the output of switching element 3 and turns switching element 1 ON and OFF via an intensifier; oscillator,
Reference numeral 5 denotes an intensifier that increases the output of the rectangular wave oscillator 4 and opens and closes the switching element 1. Next, the operation of the above configuration will be explained with reference to the circuit diagram illustrated in FIG. 2.

When no current flows through the current supply circuit to the globe lug P, the transistor Q2, which is the switching element 3, is turned on, and the output of the rectangular wave oscillator 4 is at the same potential as the battery V.

When the battery V side terminal a and the globe lug side terminal b of the switch S are closed to start the diesel engine, the output of the square wave oscillator 4 is increased by the multiplier 5, which turns on the transistor QI, which is the switching element 1. As a result, the globe lug P is energized. As a result, the temperature of the globe lug P rises and its resistance value also increases, so that the current is gradually reduced. As the current decreases, the potential difference across the detection resistor Rs decreases, and when the potential of the input voltage VII of the comparator AI set by the resistors R1 and R2 reaches the reference potential V12 (Figure 4 A), the comparator 2 Since the output of is inverted, switching element 3
The transistor Q2 is turned off (Fig. 4). Therefore, the rectangular wave oscillator 4 having the comparator A2 starts oscillating a voltage (FIG. 4C, 2) with a time constant defined by the resistor R3 and the capacitor CI. The output of this square wave oscillator 4 (fourth
) is multiplied by transistors Q3 and Q4 of multiplier 5, and transistor QI of switching element 1 is turned ON-
Since it is turned off and the current to the globe lag P is interrupted, the average value of the current decreases, the temperature of the globe lag P decreases, and converges to the set value of the comparator 2. However, if the ambient temperature of the glow 7; ug decreases due to some reason, the resistance value of the globe lag P decreases, the output of the comparator 2 is inverted again, and the transistor Q2 of the switching element 3 is turned on, so the oscillation stops. However, the transistor QI of the switching element 1 becomes conductive, and the current flow to the globe lag P increases. That is, the number of times the switching element 3 that controls the oscillator 4 is turned ON and OFF changes depending on the temperature around the globe lug P, and the ON time of the oscillator changes, thereby increasing or decreasing the energization time of the current flowing through the globe lug. still,
In place of the square wave oscillator 4, a diode 01 shown in FIG.
If the circuit 14 for setting the duty ratio provided with D2 is used, the followability will be even better.

That is, in the oscillator 4, CI is charged and discharged via the resistor R3, and the ratio of tl and t2 in FIG. 4E is constant, but in the circuit 14 in FIG. Since the resistances can be set independently, the ratio of tl and t2 can be set freely, and the followability of temperature control can be improved. The present invention has the above configuration, and includes a globe lag having a positive resistance-temperature characteristic, a detection resistor, a switching element, which is connected in parallel to the detection resistor, and detects the potential difference across the detection resistor and compares it with a reference potential. It has a comparator AI, a comparator A2, and a rectangular wave oscillator having a capacitor CI charged by the output thereof and whose duty ratio is controlled by the output of the comparator AI, and a control circuit that controls the resistance change due to the temperature of the globe lag. Since the switching element is turned on and off by detecting It is possible to control the afterglow of the engine, reduce the noise and vibration of the diesel engine, purify the exhaust gas, and prevent wire breakage due to overheating of the globe lugs.

Furthermore, it is easy to install and can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a diesel engine child heat control device according to the present invention, FIG. 2 is an electric circuit diagram showing one embodiment thereof, and FIG.
The figure is a major electric circuit diagram showing another embodiment, and FIG. 4 is a time chart for explaining the operation of the embodiment shown in FIG. 2. In the diagram: V...Battery, S...Switch, Rs...
...detection resistor, P...globe lug with positive resistance temperature characteristics, 1, 3... switching element,
2... Comparator, 4... Square wave oscillator. Figure 1 Figure 3 Figure N Vertical diagram

Claims (1)

[Claims] 1. In a preheating device for a diesel engine that energizes a glow plug attached to the engine via a battery output switch, the glow plug has a positive resistance temperature characteristic;
A detection resistor and a switching element connected in series between the switch and the glow plug, a comparator A1 connected in parallel to the detection resistor for detecting a potential difference across the detection resistor and comparing it with a reference potential; and a comparator A2. and a rectangular wave oscillator having a capacitor C1 charged by the output thereof and whose duty ratio is controlled by the output of the comparator A1.The output of the rectangular wave oscillator turns the switching element ON and OFF.
Preheating control for a diesel engine, characterized in that the control circuit comprises a control circuit that controls the temperature of the glow plug, and is capable of controlling the temperature of the glow plug within a set range by changing the amount of current applied to the glow plug according to changes in the resistance value of the glow plug. Device.