JPS5941023B2 - Diesel engine starting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a starting device for a diesel engine, and particularly to control of a fuel increasing device and a glow plug during cold starting.

Conventionally, when cold starting a diesel engine, the glow plug is first preheated before cranking, and after the glow plug becomes red hot, the key switch is set to the starter position to energize the starter and glow plug, and the engine rotation speed is Activate the fuel increase device manually or automatically to increase the amount of fuel supplied.

When the engine completely explodes, the key switch is returned from the starter position to the on position, but at the same time, the power to the glow plug is cut off, so when the engine temperature is low, the combustion of the air-fuel mixture in the cylinder becomes incomplete and becomes self-sustaining. Operation becomes impossible and the engine stops.

In order to improve the above points, we developed a method that allows the glow plug to be energized by operating the manual switch even after the key switch is returned from the starter position to the on position after the engine has completely exploded, and also detects the engine cooling water temperature or atmospheric temperature. A method has been proposed in which a timer circuit is provided to operate the glow plug and the fuel increaser for a predetermined period of time regardless of the engine rotational speed when the engine temperature is low.

However, the former method is not only cumbersome as it requires manual operation, but also, if the glow plug is energized for a long time, when the engine reaches high rotation speeds (e.g. over 200 rpm), the glow plug itself will be affected by the combustion heat of the air-fuel mixture in the cylinder and the energization. The glow plug may become abnormally high in temperature due to the heat generated by it, and there is a risk of melting.

Contrary to the above, if the power to the glow plug is cut off too early (before the engine reaches idling speed), the fuel injected into the combustion chamber of the engine will not be sufficiently atomized, making it difficult to start and sustain operation. This has the disadvantage that a large amount of unburned air-fuel mixture is released.

Furthermore, in the latter method, the temperature inside the cylinder is not directly detected, so even if the engine speeds up and the temperature inside the cylinder becomes high, there is a risk that the glow plug will continue to be energized and the amount of fuel will continue to increase. There is a risk that the glow plug will be abnormally heated and melted due to the combustion of excess fuel and the heat generated by energization.

The present invention has been made in view of the above problem, and the engine rotation speed reaches a predetermined value (a value near the idle link rotation speed) even after the key switch is returned from the starter position to the on position after the engine has completely exploded. By automatically energizing the glow plug and operating the fuel increaser at the same time, the diesel engine can be started to prevent glow plug cyp loss, ensure continuous startup operation, and shorten the warm-up time. The purpose is to provide equipment.

The present invention will be described in detail below based on the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention.

In FIG. 1, 1 is a key switch, and the off position is 1.
A, has an on position 1B and a starter position 1C.

2 is a battery, 3 is a fuse, 4 is an alternator, and 4A is a neutral point.

Reference numeral 5 denotes a temperature sensor that detects the engine cooling water temperature or the exhaust gas temperature, and a contact is turned on when the temperature is equal to or higher than a set value (for example, the engine cooling water temperature is 30° C.).

Also, 6 is a control circuit (details will be described later), and alternator 4
input the output signal of the neutral point and the signal of the temperature sensor 5,
It has a holding circuit that continues to output an output signal when at least one of the two signals exceeds a set value.

Moreover, I is a relay, which has a coil 7A, a normally closed contact 7B, and a normally open contact IC.

8 is an actuator for increasing the amount of starting fuel, and when energized, a fuel control lever (not shown) operates in the direction of increasing the amount of starting fuel.

9 is a relay having a coil 9A and a normally open contact 9B;
10 is a lamp, 11 is a glow plug, and 12 is a timer circuit, which operates for, for example, 30 seconds after the power is turned on when the temperature sensor 13 is off, and for 15 seconds when it is on, and receives a signal from the relay 7 (contact point). If 7C is on (output) is given, all (does not operate).

In addition, 13 indicates that the temperature is the set value (for example, the engine cooling water temperature is 20℃)
) Temperature sensor that turns on when above and turns off when below.
14 is a relay equipped with a coil 14A and a normally open contact 14B, 15 is a thyrisk, 16 is a resistor, and 17 is a starter relay.

Next, the operation will be explained.

First, when the key switch 1 is placed in the on position 1B during a cold start of the engine, current flows through the control circuit 6 and the timer circuit 12.

At this time, the engine is stopped, so the set rotation speed (for example, 8
Since the engine cooling water temperature is below the set value (for example, 30°C) and the temperature sensor 5 is off, the control circuit 6 does not send an output, and therefore the relay 7
is not energized, so the normally closed contact IB is on.

Therefore, the actuator 8 is actuated to move a fuel control lever (not shown) in the fuel increasing direction.

Also, the timer circuit 12 operates at the same time as the power is turned on, and when the temperature sensor 13 is off (for example, when the cooling water temperature is below 20°C), it is 30 seconds, and when it is on (when it is above 20°C), it is 1 second.
Energize relay 14 for 5 seconds.

Therefore, the contact 14B is turned on and the relay 9 is energized, so the contact 9B is turned on, and as a result, the glow plug 1
1 from the battery 2, the glow plug 11 is preheated for a predetermined period of time (30 seconds or 15 seconds as described above).

During this preheating time, the lamp 10 is lit to indicate that preheating is in progress.

Next, when the timer time elapses, the contact 14B of the relay 14 is turned off, and as a result, the contact 9B of the relay 9 is also turned off, so that the preheating of the glow plug 11 is completed, and at the same time the lamp 10
The light turns off to indicate that preheating is complete.

When the key switch 1 is set to the starter position 1C (both 1B and 10 are on at this time) after the preheating is completed, current flows to the starter relay 17, the starter motor is operated, and the engine is cranked.

At the same time, a trigger signal is applied to the gate of the thyristor 15 via the resistor 16, which turns on the thyristor 15, which excites the relay 9 and turns on the contact 9B, causing current to flow through the glow plug 11 and heat it. .

Note that at this time, since the actuator 8 is operating as described above, the amount of fuel is increased.

Next, when the engine completely explodes, the key switch 1 is returned from the starter position 1C to the on position 1B, but the thyristor 15 has a self-holding function and remains on, so the glow plug continues to be heated and the amount of fuel increases. is also being continued.

In this state, when the engine warms up and the rotation speed reaches the set value (for example, 800 rpm), the control circuit 6 sends out an output, the relay 7 is energized, the normally closed contact γB is turned off, and the normally open contact IC is turned off. Turns on.

Therefore, the operation of the actuator 8 is stopped, the fuel increase is completed, and the thyristor 15 is turned off, so that the heating of the glow plug 11 is also completed.

Note that the control circuit 6 has a holding circuit, and once the rotation speed is
If the set value is exceeded, the output will continue to be output.

The control circuit 6 also sends out an output when the temperature sensor 5 is turned on, but since the rate of increase in engine cooling water temperature is slower than the rate of increase in rotational speed, the rotational speed is higher during cold starting. The set value is reached first.

As mentioned above (during a cold start, the amount of fuel is increased and the glow plug is heated until the engine speed reaches the set value, so that continuous startup operation is ensured and burnout of the glow plug is prevented. I can do it.

Next, the warm start time will be explained.

First, the engine cooling water temperature at startup is the set value of the temperature sensor 13 (
For example, when the temperature is 20'C or higher, the preheating time is shortened to 15 seconds as described above.

When the engine cooling water temperature is higher than the set value of the temperature sensor 5 (for example, 30°C), the temperature sensor 5 is turned on, and the control circuit 6 outputs the output at the same time as the key switch 1 is turned on. The relay 7 is energized, the normally closed contact γB is turned off, and the normally open contact IC is turned on.

Therefore, a signal is sent to the timer circuit 12 via the normally open contact IC, and since the timer circuit 12 does not operate, the relay 1
4 is not energized and the glow plug is not preheated.

Further, since the normally closed contact 7B of the relay 7 is turned off, the actuator 8 does not operate and the fuel amount is not increased.

In other words, during a warm start (when the engine temperature is high enough and there is no need to preheat or increase the amount of fuel), neither the amount of fuel is increased nor the glow plug is heated, so problems such as burnout of the glow plug will not occur. .

Next, FIG. 2 is a diagram showing one embodiment of the control circuit 6, which is composed of a waveform shaping circuit 6A, a switching circuit 6B, and a holding circuit 6C.

In addition, the same reference numerals as in FIG. 1 indicate the same parts.

In FIG. 2, a signal output from the neutral point 4A of the alternator 4 that changes in synchronization with the engine rotational speed is converted into a pulse signal (square wave) by a waveform shaping circuit 6A with a repetition period corresponding to the engine rotational speed. converted.

Next, in the switching circuit 6B, while the pulse signal is at a high level, the transistor Q0 is turned on and the capacitor C1 is charged, and while the pulse signal is at a low level, the transistor Q1 is turned off and the charge on the capacitor C is discharged. It is discharged through the resistor R1.

Therefore, as the repetition period of the pulse signal becomes shorter (the rotational speed increases), the potential of the ground terminal of the capacitor C1 (base terminal of the transistor Q2) decreases, and when the value falls below a predetermined value, the transistor Q2 turns on. .

Therefore, l transistor Q3 is also turned on, and a trigger signal is given to the gate electrode G of thyristor Q4 of holding circuit 6C, so thyristor Q4 is turned on, and relay 7
A current flows through the coil 7A to excite it.

Note that the thyristor Q4 has a self-holding function, so that once a trigger signal is applied, it remains on even if the trigger signal disappears as long as the power supply voltage VCC is applied.

Also, as soon as the temperature sensor 5 turns on, the capacitor C1
is charged, transistor Q2. is charged regardless of the repetition period of the pulse signal. Q3 turns on and thyristor Q4 is triggered.

Next, FIG. 3 is a diagram showing another embodiment of a sensor for detecting the rotational speed of the engine.

First, Figure 3A shows a magnet 18 that rotates in synchronization with the engine rotation.
and a reed switch 19, and the reed switch 19 is turned on each time the protrusion of the magnet 18 approaches.

In addition, the opening in Figure 3 shows a magnet 20 that rotates in synchronization with the engine rotation.
and a coil 21, and the voltage generated in the coil 21 in response to 200 rotations of the magnet is used as a signal.

3C is equipped with a switch mechanism that detects the engine lubricating oil pressure and turns off when the oil pressure corresponding to the set rotational speed is reached.

In FIG. 3C, 22 is a diaphragm that divides an atmospheric chamber 23 (23A is a pore) and a hydraulic chamber 24.

25 is a threaded portion that is screwed into the engine oil pressure passage (not shown);
25A is a passage that leads the engine oil pressure to the hydraulic pressure chamber 24; 26, 27;
28 is a stopper that holds the diaphragm 22 between each other; 28 is a rod that moves integrally with the diaphragm 22;
A rod 31 sliding with 9 is moved up and down via a spring 30.

When the engine lubricating oil pressure reaches the oil pressure corresponding to the set rotational speed, the rod 31 moves upward against the spring 32 to push up the contact piece 33 and cut off the conduction between the contacts 34 and 35.

Note that if a sensor such as that shown in FIG. 3C is used, the contact point 34
．． When 35 is off, thyristor Q4 in Fig. 2 is set to 1-'
Since it is sufficient to configure the control circuit 6 so that the control circuit 6 is configured as shown in FIG.

As explained above, according to the present invention, during a cold start when the engine temperature is below the set value, the engine rotation speed reaches the set rotation speed even after the key switch is returned from the starter position to the on position after the engine has completely exploded. By increasing the amount of fuel and continuing to energize the glow plug until the start of the engine, it is possible to ensure starting and sustained operation, and to prevent burnout of the glow plug.

If the above-mentioned set rotational speed is set to a value near the idle link rotational speed, for example, about 400 to 1.50 Orpm, starting and sustained operation will be sufficiently possible in practice, and high temperature at high rotations (about 200Orpm or more) will be avoided. There is also no risk of combustion gas coming into contact with the glow plug.

In addition, during a warm start when the engine temperature is above the set value, regardless of the engine rotation speed (no electricity is applied to the glow plugs, no fuel is increased, etc.), battery discharge can be prevented as much as possible, and the battery capacity can be reduced. There are effects such as being able to reduce the weight and cost of the vehicle and improving the durability of the glow plug.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is an embodiment of a control circuit, and FIG. 3 is an embodiment of a sensor for detecting rotational speed. Explanation of symbols, 1...Key switch, 1A...
...Off position, 1B...On position, 1C...
...Starter position, 2...Battery, 3.
... Fuse, 4 ... Alternator, 4
A... Neutral point, 5... Temperature sensor, 6
...Control circuit, I...Relay, 8...
...Actuator, 9...Relay, 10
...Lamp, 11...19. glow plug,
12... Timer circuit, 13... Temperature sensor, 14... Relay, 15... Thyristor, 16... Resistor, 17... ...Starter relay.

Claims (1)

[Claims] 1. A first signal is output when both the condition that the engine rotational speed is equal to or higher than the set rotational speed and the condition that the engine temperature is equal to or higher than the set value are satisfied, and at least both of the above conditions are satisfied. a first circuit that stops the first signal when one condition is satisfied; an actuator that increases starting fuel; a glow plug; and a glow plug that stops the first signal when one of the conditions is satisfied; and a second circuit that starts the operation and energization of the glow plug, and stops the operation and energization when the first signal is stopped. 2 The above set rotation speed is 150Orpm or more than 40Orpm.
The starting device for a diesel engine according to claim 1, characterized in that the starting device is set to a certain value below pm. 3. The second circuit includes a timer circuit that outputs a second signal for a predetermined period of time from the time when the first signal is applied and the key switch is turned on;
a circuit that operates the actuator and energizes the glow plug while the first signal is being applied and while the first signal is being applied even after the key switch is set to the start position. A starting device for a diesel engine according to claim 1.