JP2554124B2 - Starting aid for direct injection diesel engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a starting assist device for a direct injection diesel engine.

[Prior Art] In a diesel engine having no auxiliary combustion chamber, in order to stabilize the engine in cold weather, when the temperature becomes lower than a predetermined temperature, before starting the engine, for example, by a control circuit 20 as shown in FIG. , The glow plug G is energized by a relay RL for a predetermined time determined by a timer 22 equipped with a thermoswitch 21 that opens a circuit when the temperature falls below a predetermined temperature, and the timer 22 is reset during cranking of the engine to complete explosion of the engine. After that, afterglow is performed for a predetermined time. And
The thermoswitch 21 is normally set to a predetermined temperature of about 0 ° C.

[Problems to be Solved by the Invention] However, in such a control circuit 20, the thermoswitch 21 operates in exactly the same manner even when the cooling water temperature is near a predetermined temperature or in an extremely cold temperature lower than that. Therefore, the energization time of the glow plug G set by the timer 22 must be set so that the durability of the glow plug G is not deteriorated by the energization when the temperature is relatively high. Therefore, during extremely cold weather, the energizing time of the glow plug G for afterglow or the like becomes insufficient, and there is a problem that it is difficult to stabilize the rotation of the engine after starting.

It is an object of the present invention to provide a starting assist device for a diesel engine, which is capable of efficiently energizing a glow plug G with a simple structure.

[Means for Solving the Problems] The present invention provides a self-control glow plug provided in a combustion chamber of an engine, a relay for energizing the glow plug, and a water temperature sensor for detecting a cooling water temperature of the engine. A water temperature signal generating means for generating a voltage according to the water temperature detected by the water temperature sensor, and an operation that starts when the key switch is turned on, and is determined according to the output voltage of the water temperature signal generating means. A first timer which operates for a time of 1, a display means for displaying an operation of the first timer, an operation which starts when the key switch is turned on, and which corresponds to an output voltage of the water temperature signal generating means. A second timer that is determined and that operates for a second time longer than the first time;
The energizing means for energizing the glow plug by driving the relay during the operation of the timer, the second timer is restarted when the key switch is in the energizing position of the starter motor, and the glow energizing means operates the glow switch. Adopting a technical means including an energization extension means for energizing the plug and an energization stopping means for stopping the energization of the glow plug by the energizing means when the water temperature detected by the water temperature sensor is equal to or higher than a predetermined temperature. .

[Operation] In the present invention, when the cooling water temperature of the engine is equal to or lower than the predetermined temperature, the operating time of the first timer and the second timer is determined according to the cooling water temperature of the engine, and the key switch is turned on. Then, the display is made and the glow plug is energized in accordance with each operation time. When the key switch is set to the energizing position of the start motor when the display is finished, the engine is started, and at this time, the glow plug is energized by the energizing extension means and the second timer is restarted. Therefore, afterglow is further performed for the operation time of the second timer after the key switch is returned to the ON position.

On the other hand, when the cooling water temperature of the engine is equal to or higher than the predetermined temperature, the glow plug is not energized at all.

EFFECTS OF THE INVENTION In the present invention, the preheating time to the glow plug is determined according to the cooling water temperature of the engine, and the afterglow time after the complete explosion is also determined according to the cooling water temperature. Even at times, sufficient electricity can be supplied. If the cooling water temperature is not low, the glow plug will be de-energized and the energization time will be set to a short time so that the glow plug is not energized more than necessary, preventing overheating of the glow plug and consumption of the battery. Therefore, it is possible to efficiently conduct electricity.

EXAMPLES Next, the present invention will be described based on examples.

The direct injection diesel engine start assist device shown in FIG. 1 includes a key switch SW for controlling the start and stop of the engine, a glow plug G provided in the diesel engine, and a resistance that changes according to the temperature of the engine cooling water. A water temperature sensor S indicating a value, a relay RL for energizing the glow plug G, a lamp PL indicating completion of preheating, and a control circuit 10 for controlling the lamp PL and the relay RL based on the temperature detected by the water temperature sensor S. Consisting of a battery B mounted on the vehicle
Operated by.

The key switch SW has OFF, ON and ST positions. The glow plug G is energized in the ON position and the engine is cranked in the ST position.

In the glow plug G, a main heating element made of an Fe-Cr alloy, whose resistance value hardly changes due to temperature rise, and a control heating element made of iron, which shows a large resistance value change due to temperature rise, are connected in series in the surrounding tube. As shown in FIG. 2, the surface temperature of the tube is self-controlled to a constant temperature according to the applied voltage, as shown in FIG.

The water temperature sensor S detects the cooling water temperature of the diesel engine by a thermistor whose resistance value decreases as the temperature rises, and the voltage applied from the constant voltage power supply section 18 is divided by the resistor R1 connected in series. Is output as the detection voltage Va.

The control circuit 10 includes a water temperature signal generation unit 11, a lamp timer 12, a display unit 13, a glow plug timer 14, and a glow plug energization unit 1.
5, energization extension part 16, energization stop part 17 and constant voltage power supply part 18
Consists of

The water temperature signal generation unit 11 calculates the voltage difference between the divided voltage Vb obtained by dividing the applied voltage V of the constant voltage power supply unit 18 by the resistors R2 and R3 and the detection voltage Va input via the resistor R4 by the operational amplifier OP.
In the part that differentially amplifies by 1 and outputs as the water temperature signal Vc, the higher the detected cooling water temperature, the higher the water temperature signal Vc.
Is output.

The lamp timer 12 is for measuring the time until the glow plug G is preheated to a temperature suitable for starting the engine, and uses the operational amplifier OP2 as a comparator to connect the resistor R5 and the capacitor C1. The high level is output for the time ta until the potential of P1 becomes higher than the divided voltage Vd by the resistors R6 and R7. Here, the capacitor C1 is charged according to the water temperature signal Vc of the water temperature signal generation unit 11 via the resistor R8 and the diode D1, and the higher the water temperature signal Vc, the faster the charge.
The operating time of the lamp timer 12 becomes shorter as the cooling water temperature becomes higher. In this example, as shown in FIG.
In the range up to ° C, it changes within the operation time of 6 to 1 second, and below -20 ° C and above +5 ° C, the operation is performed for a fixed time of 6 seconds and 1 second, respectively.

The display unit 13 is a circuit for informing the driver of the preheating state by the glow plug G. When the high level output of the lamp timer 12 is input to the transistor TR1 via the resistor R9, the transistor TR1 is turned on and the diode TR1 is turned on. The lamp PL is energized and lit via D2 and the resistor R10, and is extinguished when the output of the lamp timer 12 becomes low level.

The glow plug timer 14 is a time measuring means for determining the energization time of the glow plug G. Like the lamp timer 12, the operational amplifier OP3 is used as a comparator, and the potential at the connection point P2 between the resistor R11 and the capacitor C2 is used. Outputs high level for the time tb until the voltage becomes higher than the divided voltage Ve by the resistors R12 and R13.The capacitor C2 is connected to the resistor R14 and the diode D3.
The battery is charged in accordance with the water temperature signal Vc of the water temperature signal generator 11 via, and in this embodiment, as shown in FIG.
In the range up to ℃, it changes within the operating time of 60 to 1.5 seconds respectively, and below -20 ℃ and above +0 ℃ 60 seconds and 1.
It will operate for a fixed time of 5 seconds.

The glow plug energization unit 15 includes a relay RL, a transistor TR2 energizing the relay RL, and a switching transistor TR3, and when the output of the glow plug timer 14 input via the resistor R15 is at a high level, or The signal from the energization extension 16 described below drives the relay RL to energize the glow plug G.

When the key switch SW is set to the ST position, the energization extension part 16 causes the glow plug energization part 15 to pass through the diode D5 and the resistor R17 by the voltage Vf applied to the diode D4 via the resistor R16 when the power supply voltage of the battery B is set. Driven and relay RL
The transistor TR4 discharges the electric charge of the capacitor C2 and resets the glow plug timer 14. Further, the capacitor C1 is forcibly charged via the diode D6 and the resistor R18 to make the lamp timer 12 time up.

The energization stopping unit 17 is a circuit for stopping energization to the glow plug G when the cooling water temperature is higher than the predetermined temperature 5 ° C., and inputs the detection voltage Va by the water temperature sensor S to the operational amplifier OP4, and the detection voltage Va is When it is lower than the voltage Vg divided by the resistors R19 and R20, it outputs a high level as the output of the operational amplifier OP4. This signal causes the transistor TR
The transistor 5 is turned on, and the input voltage of the transistor TR3 is set to the low level. Therefore, the transistors TR3 and TR2 are both turned off, and the glow plug G is not energized by the relay RL.

The constant voltage power supply unit 18 stabilizes the voltage supplied from the battery B to particularly stabilize the operation of each operational amplifier.

Next, the operation of the starting assist device for the diesel engine of this embodiment will be described.

(B) When the cooling water temperature is lower than 5 ° C When the user turns the key switch SW from the OFF position to the ON position at time t0, the lamp timer 12 and the glow plug timer 14 start their respective operations, as shown by the solid line in Fig. 5. As described above, the lamp PL is turned on and the glow plug G is energized by the relay RL. At this time, the operating time of each timer is
Depending on the cooling water temperature T, time ta (1 to 6 seconds), time tb (1.
5 to 60 seconds) respectively.

When the time ta elapses, the lamp PL is turned off, and accordingly, when the driver sets the key switch SW to the ST position at time t1, the starter motor rotates to crank the engine.
At this time, the glow plug energization section 15 energizes the glow plug G by the energization extension section 16 regardless of the output of the glow plug timer 14, and the glow plug timer 14 energizes the energization extension section.
It is reset by the signal from 16.

When the engine is completely detonated at time t2 and the key switch SW is returned to the ON position, the glow plug timer 14 restarts the operation at time tb from this time t2, and the glow plug energization unit 15 accordingly responds to the time The glow plug G is continuously energized and afterglow is performed until time t3 when tb elapses.

At this time, the temperature of the glow plug G is maintained at a high temperature by energization until time t3 as shown by the solid line in FIG.

When the driver does not perform the cranking operation at time t1, the relay RL is connected to the glow plug G from time t0 to time t3 when time tb elapses, as shown by the broken line in FIG.
Energize, then stop energizing the glow plug G
Accordingly, the temperature of s also rapidly decreases after time t3.

(B) When the cooling water temperature is 5 ° C or higher When the key switch SW is turned to the ON position at time t0, as shown in Fig. 6, the lamp PL lights up for the shortest time of 1 second at time ta and then turns off immediately. . On the other hand, glow plug G
Since the power supply is stopped by the power supply stopping unit 17, the power supply is not supplied at all. When the driver cranks the key switch SW at the ST position at any timing, the engine will completely explode.

As described above, according to the present invention, with a simple configuration,
Efficient preheating can be performed. In addition, when the temperature becomes high and preheating is unnecessary, the glow plug is not energized, so that it is possible to prevent overheating of the glow plug and consumption of the battery. Furthermore, since the afterglow time after the complete explosion is determined based on the cooling water temperature, it is possible to ensure the rotational stability of the engine after the complete explosion even in extremely cold weather.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a starting aid device for a direct injection diesel engine showing an embodiment of the present invention, FIG. 2 is a time chart showing temperature characteristics of a glow plug of this embodiment, and FIG. 3 is a lamp of this embodiment. FIG. 4 is a characteristic diagram showing operating time characteristics with respect to cooling water temperature of the timer, FIG. 4 is a characteristic diagram showing operating time characteristics with respect to cooling water temperature of the glow plug timer of this embodiment, and FIGS. 5 and 6 are direct injection type of this embodiment. FIG. 7 is a time chart for explaining the operation of the starting auxiliary device for the diesel engine, and FIG. 7 is a block diagram showing the configuration of the conventional starting auxiliary device for the direct injection diesel engine. In the figure, G ... Glow plug, S ... Water temperature sensor, PL ...
Lamp (display means), RL ... Relay, 11 ... Water temperature signal generator (water temperature signal generator), 12 ... Lamp timer (first
No. timer), 13 ... Display unit (display unit), 14 ... Glow plug timer (second timer), 15 ... Glow plug energizing unit (energizing unit), 16 ... Energizing extension unit (energizing extending unit) , 17 …… Power supply stop part (power failure stop means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-61-294171 (JP, A) JP-A-58-140477 (JP, A) Actually open 59-123673 (JP, U) Actual-open Sho 57- 83271 (JP, U) Actually opened 56-161182 (JP, U) Actually opened 56-138157 (JP, U)

Claims (1)

(57) [Claims] 1. A self-control glow plug provided in a combustion chamber of an engine, a relay for energizing the glow plug, a water temperature sensor for detecting a cooling water temperature of the engine, and a water temperature sensor for detecting the cooling water temperature. And a water temperature signal generating means for generating a voltage according to the water temperature, and a first operation which is started when the key switch is turned on and which is operated for a first time period determined according to the output voltage of the water temperature signal generating means. A timer, display means for displaying an operation of the first timer, starting operation when the key switch is turned on, determined according to an output voltage of the water temperature signal generating means, and the first A second timer that operates for a second time longer than the time; energizing means that drives the relay to energize the glow plug during operation of the second timer; and the key switch that connects the starter motor. When the second position is set to the position, the second timer is restarted, and the energizing means energizes the glow plug by the energizing means; and the energizing means when the water temperature detected by the water temperature sensor is equal to or higher than a predetermined temperature. A starting auxiliary device for a direct injection diesel engine, comprising: an energization stopping means for stopping energization of the glow plug.