JPS629729B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake air preheating display device for a diesel engine, and in particular, to a starting device for a diesel engine having an intake air preheating device that ignites and burns fuel using an electric heating plug in an intake pipe. The present invention relates to an intake air preheating display device for a diesel engine suitable for occasional use.

[Conventional technology]

In order to make it easier to start diesel engines in cold weather, conventional diesel engines have been designed to preheat the intake air.One method of preheating the intake air is to attach a heating wire inside the intake pipe and heat it to red hot when it is energized. A device is known from Japanese Patent Laid-Open Publication No. 50-21150, etc., in which a fuel is fed and ignited and combusted by the heat of the electric heating plug. Compared to other starting preheating methods, this method consumes less power for heating and has the advantage of reducing the load on the battery during startup. However, after the power switch is closed, the heating wire heats up and it takes 10 to 20 seconds for the fuel to ignite and the engine to start, and combustion takes place in the intake pipe, making it difficult to confirm ignition. Therefore, after closing the power switch, the engine may be started before the fuel ignites, resulting in a failure to start, or the time between the fuel igniting and the starting operation may be too long, causing oxygen in the intake pipe to evaporate. There were drawbacks such as insufficient starting, resulting in failure to start. Matazane Kosho 46-22273
The publication describes that a charging time-limiting circuit consisting of a resistor and a capacitor is connected in parallel to an electric heating plug, a thermistor is connected to the time-limiting circuit to control the charging time constant of the resistor and the capacitor according to the ambient temperature, and the voltage across the capacitor is A device is disclosed that includes an operation indicator that receives electricity when a certain value is reached, and displays an appropriate glow time on the operation indicator depending on the outside temperature.

[Problem to be solved by the invention]

However, these conventional examples do not take into account the second and subsequent starting operations that are performed after the first ignition failure, and if the engine fails to start for the first time, the capacitor This means that the starting operation must be repeated at regular intervals determined by the timer circuit of the resistor and the resistor. However, if the electric heating plug is preheated for the same amount of time as the first time even though it is already in a heating state, the fuel will vaporize in the intake air preheating device and block the ignition outlet. Therefore, the fuel is stopped and combustion becomes impossible, resulting in the inconvenience that heated air is not supplied to the engine and the engine cannot be started.

The purpose of the present invention is to not only display that the fuel has ignited and the diesel engine is ready to start after a predetermined time period has elapsed, but also to enable the engine to be restarted from the second time onward if the diesel engine is restarted continuously. To provide an intake air preheating display device for a diesel engine, which enables reliable and timely starting.

[Means for solving problems]

The above object is to provide a semiconductor timer circuit that operates a semiconductor switch when a predetermined time period has elapsed, and a display means that performs a display operation based on the operation of the semiconductor switch, and to provide a time constant of a discharge circuit of a capacitor constituting the semiconductor timer circuit. This is achieved by configuring the temperature to change according to the temperature drop characteristics of the electric heating plug over time.

[Effect]

With this configuration, if the first start fails and the electric heating plug is in a heating state, the timer period for the second start operation will be shortened, and the intake air preheating device will ignite at an early stage. It is possible to display that This solves the conventional problem of the second and subsequent intake air preheating times being too long, causing fuel to vaporize within the intake air preheating device and blocking the ignition port.

〔Example〕

The display device of the present invention will be explained in detail below with reference to the illustrated embodiments. In Fig. 1, 1 is a power source such as a battery, 2 is an electric heating plug for igniting fuel in the intake air preheating device, which is connected in parallel to both ends of the power source 1 via a switch 3, and this electric heating plug 2 is a diesel engine (not shown). It is attached so that it penetrates the pipe wall of the intake pipe and projects inside the pipe. Fuel for intake air preheating is led from the fuel tank to the intake pipe through a valve via a pipe line. For example, when the switch 3 is closed, the red heat of the power plug 2 heats the valve part, and the valve opens due to thermal expansion. The structure is such that fuel is automatically dripped onto the electric heating plug 2 and ignited and combusted. 4 is a semiconductor timer circuit which starts a timed operation when electricity starts to be applied to the electric heating plug 2 and operates a semiconductor switch when a predetermined time period has elapsed;
1 is a lamp serving as a display means that performs a display operation according to the operation of a semiconductor switch of the semiconductor timer circuit 4. The semiconductor timer circuit 4 includes a capacitor 8 connected in parallel to both ends of the electric heating plug 2 via a resistor 6 and a diode 7. The time limit of the timer is determined. resistance 6
A series circuit of a resistor 9 and a diode 10 is connected in parallel to both ends of the series circuit of the diode 7 and the electric heating plug 2, thereby forming a discharge circuit for the capacitor 8. One end of the capacitor 8 on the diode 7 side is connected to the base of a transistor 12 via a constant voltage diode 11, and the collector of the transistor 12 is connected to the electric heating plug 2 and the switch 3 via a resistor 13.
connected to the connection point. transistor 12
The emitter of is connected to the base of a transistor 14 whose emitter is connected to the other end of the capacitor 8,
A lamp 5 is connected between the connection point between the electric heating plug 2 and the switch 3 and the collector of the transistor 14. Transistors 12 and 14 constitute a semiconductor switch that operates when a predetermined time period has elapsed, and when transistor 14 becomes conductive, lamp 5 lights up.

In the above-mentioned device, when the switch 3 is closed when the diesel engine is started, the electric heating plug 2 starts to be energized, and at the same time, charging of the capacitor 8 through the resistor 6 and the diode 7 starts. The terminal voltage of the capacitor 8 rises according to a time constant determined by the resistor 6 and the capacitor 8, and when the voltage across the capacitor exceeds the Zener voltage of the voltage regulator diode 11, a base current flows to the transistor 12 through the voltage regulator diode. flows. This causes transistors 12 and 14 to become conductive, causing current to flow through lamp 5 and lighting the lamp. Therefore, it is important to know the temperature rise characteristics with respect to time of the electric heating plug 2, and calculate the time required for the terminal voltage of the capacitor 8 to exceed the Zener voltage of the constant voltage diode 11, and the ignition time of the intake air preheating device heated by the electric heating plug 2. By setting the charging time constant of the capacitor 8 so that the values are approximately equal, the desired display can be performed. The setting of the charging time constant of the capacitor 8 can be appropriately adjusted by appropriately selecting the resistance value of the resistor 6 and the capacitance of the capacitor 8. In addition, when using a power source whose voltage fluctuates, for example, a battery, the temperature of the electric heating plug 2 rises quickly when the power supply voltage is high, and conversely, when the power supply voltage is low, it takes time for the temperature to rise, which naturally takes time to ignite the intake air preheating device. However, in the semiconductor timer circuit as described above, if the voltage of the power supply 1 rises, the time for charging the capacitor 8 to a predetermined voltage becomes shorter, so if the power supply voltage rises or The time limit of the timer can be automatically shortened or extended in accordance with fluctuations in the temperature rise characteristics of the electric heating plug 2 as the temperature decreases. Furthermore, the temperature rise characteristics of the electric heating plug 2 are affected to some extent by the environmental temperature (outside temperature), but in the above display device, it is necessary to use a constant voltage diode 11 whose Zener voltage has a negative temperature coefficient; Alternatively, by using a resistor 6 having a negative temperature coefficient (for example, a thermistor), the time limit of the timer can be changed depending on the environmental temperature (outside temperature). In other words, if a voltage regulator diode 11 or resistor 6 having the temperature characteristics described above is used, the time limit of the timer can be shortened when the environmental temperature (outside temperature) is high and the temperature of the heating wire rises quickly. If the environmental temperature (outside temperature) is low and the heating wire temperature rises slowly, the time limit of the timer can be increased. This point is true in 1973-22273.
This is the same technology as that shown in the publication. In the present invention, this configuration is not an essential configuration.

Next, in the above display device, when the switch 3 is opened, the lamp 5 is turned off, the electric heating plug 2 is also cooled, the combustion valve is automatically closed, and combustion for heating the intake air is stopped, and at the same time the electric charge accumulated in the capacitor 8 is is discharged through the resistor 9, the diode 10, and the electric heating plug 2. What is particularly important here is that the time constant of this discharging circuit can be arbitrarily set regardless of the charging time constant (timer time limit) of capacitor 8, and the discharging time constant of capacitor 8 can be set at any time when the current supply is stopped. By setting the timer appropriately according to the temperature drop characteristics of the electric heating plug over time, if the switch 3 is closed again before the electric heating plug has cooled down after opening the switch 3, the time limit of the timer will change to the temperature of the electric heating plug. It can be shortened depending on the descent. As a result, it is possible to eliminate the problem of no display even though the electric heating plug has reached a predetermined temperature and the intake air preheating device is ignited. Furthermore, in this case, if a thermistor having a positive temperature coefficient that responds to the temperature of the heating wire is used instead of the resistor 9, the re-ignition time characteristics and display operation of the intake air preheating device can be changed according to the actual change in the temperature of the heating wire. can be tracked more accurately.

In the above embodiment, a lamp was used as the display means, but instead of the lamp, a light emitting diode may be connected through a resistor, and instead of these light emitters, a sounder such as a buzzer or the like may be used as the display means. Good too.

Further, although a switch consisting of two transistors is used as the semiconductor switch of the semiconductor timer, the structure of this switch is arbitrary, and a switch element other than a transistor, such as a thyristor, etc. can also be used. Furthermore, in the above embodiment, an NPN transistor was used as the transistor, but
Of course, it is possible to construct the display means by using a PNP transistor and inserting it into the ground side.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to accurately know the startable timing of the diesel engine at the same time as the ignition timing of the fuel for intake air preheating by the display means, and also to prevent the continuous restarting of the engine. This has the effect of ensuring that it is done in a timely manner.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an intake air preheating display device for a diesel engine showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Power supply, 2... Electric heating plug, 3... Switch, 4... Semiconductor timer circuit, 5... Lamp (display means), 6...
Resistor, 7... Diode, 8... Capacitor, 9... Resistor, 10... Diode, 11... Constant voltage diode, 12... Transistor, 13... Resistor, 14... Transistor.

Claims (1)

[Claims] 1 Equipped with a semiconductor timer circuit that operates a semiconductor switch when a predetermined time period elapses, and display means that performs a display operation based on the operation of the semiconductor switch, supplies fuel into the intake pipe at the time of starting, and uses an electric heating plug to ignite the engine. In the intake air preheating device for a combustion diesel engine, the semiconductor timer circuit includes:
A capacitor that is charged from the power supply via a resistor, a discharge circuit that discharges the charge of the capacitor via an electric heating plug, and a semiconductor switch that turns on and off when the terminal voltage of the capacitor reaches a predetermined value or more. An intake air preheating display device for a diesel engine, characterized in that the discharge time constant of the discharge circuit is configured to be a time constant corresponding to the temperature drop characteristic with respect to time of the electric heating plug.