JP4453442B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device having heat generating means as an ignition source used for starting an engine.

  As an engine having a heating means in an ignition source used for starting the engine, for example, there is a natural gas direct injection type engine.

  This engine employs a reliable and advantageous glow plug continuous heating method among various ignition methods. The function of the glow plug used in this method is closer to the spark plug used in the gasoline engine than the glow plug used in the diesel engine, and has not only a preheating function when starting the engine but also an ignition function during engine operation. However, it is not ignited by sparks like a spark plug, but is ignited by heat. In other words, a battery is connected to the glow plug to supply electric power, and the glow plug generates heat by electric resistance.

  Conventionally, in a natural gas direct injection type engine equipped with the glow plug, when the engine is stopped, the power supply from the battery to the glow plug is cut off.

JP 2000-130208 A Special table 2003-512555 gazette

  However, when the engine is mounted on a vehicle (including buses, trucks, etc.), when the driver temporarily stops the engine, for example, when waiting for a signal, when there is a traffic jam, when passengers get on or off, or when loading or unloading luggage When energization from the battery to the glow plug is cut, the temperature of the glow plug decreases with time. For this reason, when the engine is restarted after the predetermined time has elapsed and the temperature of the glow plug becomes equal to or lower than the predetermined temperature, the glow plug is re-energized and waits for the temperature to rise to a temperature at which the glow plug can be ignited. This requires a few seconds in practice. As a result, the restart of the engine is delayed, and the driver who restarts the engine feels the restart delay, resulting in a problem that the feeling is deteriorated.

  In particular, from the viewpoints of environmental considerations and energy conservation, the engine idling is temporarily stopped when the vehicle is equipped with the above engine when the vehicle is stopped, such as when waiting for traffic lights, during traffic jams, when passengers get on and off, or when loading or unloading luggage. When an idle start / stop system that restarts according to the driver's intention is used, if the time from engine stop to restart is relatively long, engine warm-up There is a possibility that the temperature of the glow plug is lowered to a predetermined temperature or less, and the restart delay described above frequently occurs.

  Then, the objective of this invention created in order to solve the said subject is to provide the engine control apparatus which can suppress a restart delay when restarting, after stopping an engine temporarily.

To accomplish the above object, a heating means as an ignition source used to start the engine, and control means for controlling the temperature of the heat generating means, to restart the engine after stopping the engine is running Predicting means for determining whether or not the prediction condition of the engine is satisfied, the control means determines whether or not the engine stop condition is satisfied during engine operation, and the engine is operated when the stop condition is satisfied. When the engine is stopped in a state where the stop condition is satisfied and the prediction unit satisfies the prediction condition, the temperature of the heat generating unit is maintained at a predetermined temperature in preparation for engine restart. is there.

  The heating means has a heating element connected to the battery and generates heat by electric resistance, and the control means stops energization from the battery to the heating element when the voltage of the battery is lower than a predetermined voltage. It may be.

  Prior to stopping energization of the heating element from the battery, the control means may have notification means for notifying the driver of the energization interruption.

  The control means may include means for detecting the electrical resistance of the heating element, and control the temperature of the heating element based on the electrical resistance value obtained by the means.

  The engine may be provided with automatic stop / restart means for temporarily stopping the engine under a predetermined stop condition and restarting the engine under a predetermined restart condition.

  The engine may be a natural gas direct injection engine.

  According to the present invention, when the engine is restarted, the heating means that has been held at the predetermined temperature while the engine is stopped is heated to a temperature suitable for restarting. Compared with this, the temperature raising time can be shortened and the restart delay of the engine can be suppressed. In addition, holding the heat generating means at a predetermined temperature while the engine is stopped is performed when it is predicted that the engine will be restarted in the near future after the engine is stopped, so that unnecessary preheating of the heat generating means can be prevented. .

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

  The outline of the present embodiment will be described. An engine control device according to the present embodiment is similar to a heat generating means used as an ignition source for starting the engine, a control means for controlling the temperature of the heat generating means, and after the engine is stopped. Prediction means for predicting a future restart. When the predicting means predicts that the engine will be restarted in the near future after the engine is stopped, the control means maintains the temperature of the heat generating means at a predetermined temperature while the engine is stopped. Is raised to a temperature suitable for restarting above the predetermined temperature. Thereby, the restart delay of the engine is suppressed.

  When the temperature of the heat generating means is raised from the predetermined temperature to a temperature suitable for restarting when the engine is restarted, the predetermined temperature can be increased in a time that is comfortable for the driver (for example, about 0.1 second). Set to temperature. Since the predetermined temperature varies depending on the heat generation capacity and heat capacity of the heat generating means, it is obtained in advance by experiments, simulations, and the like.

  By the way, in order to suppress the restart delay after the engine is temporarily stopped, it may be considered that the temperature of the heat generating means is always heated to a temperature suitable for restart while the engine is stopped. However, always heating and maintaining the heating means at a temperature suitable for restarting not only increases the capacity of the battery for heating the heating means and shortens its life, but also reduces the life of the heating means itself. It also leads to shorter life.

  Therefore, only when it is predicted that the engine will be restarted in the near future after the engine is stopped, the heating means is kept at the predetermined temperature lower than the temperature suitable for restarting while the engine is stopped. . Thereby, not only the restart delay of the engine is suppressed as described above, but also the enlargement and shortening of the battery can be suppressed and the shortening of the heat generating means itself can be suppressed.

  In the present embodiment, a natural gas direct injection engine is used as the engine. As shown in FIGS. 4 and 5, an injector nozzle IN for directly injecting fuel (natural gas) into the cylinder is mounted on the cylinder head SH of the engine, and a glow plug GP is used as the heating means. Is installed. In FIG. 5, V is an intake valve or an exhaust valve.

  The glow plug GP is disposed so that a portion exposed in the cylinder is close to the injector nozzle IN, a preheating function for increasing the ambient temperature in the vicinity of the injector nozzle IN when the engine is started, and an injector nozzle during engine operation It has an ignition function for heating and igniting the fuel (natural gas) injected from IN.

  The glow plug GP includes a heating element H that is connected to the battery and generates heat by electric resistance, and has a bottomed cylindrical shield S that covers the heating element H. The shield S prevents the relatively low temperature fuel from coming into direct contact with the heating element H that is red hot during preheating or ignition, and avoids damage to the heating element H due to heat shock.

  The temperature of the heating element H is controlled by adjusting the power supplied from the battery to the heating element H by a control means (ECU: engine control unit). Specifically, the control means has an electrical resistance detection means for detecting the electrical resistance of the heating element H, adjusts the power supplied to the heating element H based on the electrical resistance value obtained by this means, and Control the temperature to the desired temperature. The heating element H that generates heat due to electrical resistance generally has a correlation between temperature and electrical resistance, and detects the electrical resistance value particularly in a glow plug GP that is controlled in quality and exhibits stable performance. Thus, the temperature in the vicinity of the heat generating part can be estimated with high accuracy.

  As the electrical resistance detection means, for example, a voltage measurement unit that measures a voltage V between a current input unit and a current output unit of the heating element H and a current measurement unit that measures a current I flowing through the heating element H are provided. In this case, the resistance V is obtained by dividing the voltage V by the current I.

In the present embodiment, when the upper Symbol predicting means predicts the restart of the near future engines, even during the engine stopped electrical resistance detection means continuously measuring the electrical resistance of the heating element H, the electric resistance Based on the value, the control means adjusts the power supplied to the heating element H, and keeps the temperature of the heating element H at the predetermined temperature while the engine is stopped.

  Here, since the heating element H has been in a high temperature state by a normal operation until immediately before the engine is stopped, in order to keep the temperature of the heating element H at the predetermined temperature, the heat generation element H uses heat dissipation. It suffices to supply the heating element H with an amount of power that suppresses the reduction in temperature. Therefore, the heating element H can be held at the predetermined temperature with less electric power than when the temperature is once completely cooled and then raised to the predetermined temperature, which is advantageous in terms of power.

  By the way, even if the predicting means predicts a near future restart of the engine, there may be a case where the near future restart is not performed due to the convenience of the driver or an electrical failure. In this case, if power is continuously supplied from the battery to the heating element H, the voltage of the battery decreases, and it becomes difficult to restart the engine. For this reason, when the voltage of the battery is equal to or lower than a predetermined voltage, energization from the battery to the heating element H is stopped and preheating of the heating element H is stopped.

  In addition, when the energization to the heating element H is stopped in this way, the heating element H is cooled by heat dissipation, so that it takes some time to restart. Therefore, in order to notify the driver of this, a notification means such as a lamp / buzzer provided in the cab is operated.

Now, the prediction means is is to predict future restart near after stopping the engine, in the present embodiment that have a means for detecting that the driver is seated in the driver seat.

  As a means for detecting that the driver is seated on the driver's seat, for example, a sensor that is provided in the driver's seat and detects the amount of bending of the seat can be cited. When this sensor detects a deflection of the seat over a predetermined amount, it is determined that the driver is seated on the driver seat.

  Vehicles (including buses, trucks, etc.) equipped with the engine are temporarily stopped under the specified stop conditions from the viewpoint of environmental considerations and energy conservation, An automatic stop / restart means (idle start / stop system) of the engine to be restarted is provided. By this means, idling of the engine is temporarily stopped when the vehicle stops, such as when waiting for a signal, when there is a traffic jam, when passengers get on and off, or when loading or unloading luggage, and is restarted according to the driver's intention.

  As the stop condition, for example, the idle start / stop mode switch is turned on, the vehicle engine stop OK signal is turned on, and the driver engine stop OK signal is turned on. Etc. These conditions will be described in detail later with reference to FIG.

  The idle start / stop mode switch is provided in the driver's cab and is appropriately turned ON / OFF according to the driver's intention. The vehicle-side engine stop OK signal is generated when, for example, the vehicle speed is zero and the power steering (power steering) operation is not satisfied. The engine stop OK signal on the driver side is generated when, for example, the clutch is ON (connected state) and all the conditions such as the accelerator pedal is free (not depressed) are satisfied.

  On the other hand, examples of the restart condition include a condition that the clutch pedal is depressed, and the accelerator pedal is depressed while the shift lever is in the neutral state. When any of these conditions are met, the engine is restarted.

  The operation of this embodiment will be described with reference to FIGS.

  As shown in FIG. 1, it is first determined whether the idle stop start mode switch is ON. If no, the operation proceeds to step S6 and the normal operation (operation in which the idle start / stop system does not operate) is performed. If yes, go to step S2.

  In step S2, it is determined whether the signal “OK even if the vehicle stops the engine” is ON. If yes, the process proceeds to step S3. In step S3, it is determined whether the signal “OK even if the driver stops the engine” is ON. If yes, the process proceeds to step S4. Here, if both steps S2 and S3 are yes, it means that the engine stop condition in the idle stop start mode is satisfied. On the other hand, when at least one of steps S2 and S3 is no, the above stop condition is not satisfied, so that the routine proceeds to step S6 and normal operation is performed. In this case, the engine is not stopped by the idle stop start mode.

  In step S4, it is determined whether or not the signal “the driver is seated on the driver's seat” is ON. If the answer is yes, it is predicted that the engine will be restarted in the near future after the engine is stopped, and the process proceeds to step S5. If no, the above prediction cannot be made, and the routine proceeds to step S6 and normal operation is performed. Also in this case, the engine is not stopped by the idle stop start mode.

  In step S5, the engine is stopped.

  Next, in step S7 of FIG. 2, it is determined whether or not the electrical resistance (temperature) of the glow plug GP (heating element H) is equal to or higher than a first predetermined value (keep temperature). The keep temperature is lower than the temperature suitable for the heating element H for restarting the engine, and when the heating element H is raised from this keep temperature to a temperature suitable for restarting at the time of restarting, the driver feels uncomfortable. It is set to a temperature at which the temperature can be raised in a period without any time (for example, about 0.1 second). Since the keep temperature varies depending on the heat generation capacity, heat capacity, and the like of the heat generating element H, it is obtained in advance by experiments, simulations, and the like. The keep temperature corresponds to a predetermined temperature in the claims.

  If step S7 is YES, the process returns to the position immediately above step S7 and circulates until step S7 becomes NO. During this circulation, since the glow plug GP is above the keep temperature, there is no restart delay when the engine is restarted, and the glow plug GP is not energized for preheating. If the temperature of the glow plug GP decreases due to heat radiation and becomes less than the keep temperature after a predetermined time has elapsed, step S7 becomes no and the process proceeds to step S8.

  In step S8, it is determined whether the voltage of the battery is equal to or higher than a predetermined voltage. If yes, a small amount of power is supplied from the battery to the glow plug GP in step S9. This energization causes the glow plug GP to generate heat (preheat).

  Next, in step S10, it is determined whether an engine restart signal is output. This restart signal is output when a restart condition (for example, the clutch pedal is depressed, the accelerator pedal is depressed while the shift lever is in the neutral state) in the idle stop start mode is satisfied. If no, the process returns to step S7, and steps S7, S8, S9, and S10 are circulated until the glow plug GP reaches the keep temperature or higher. If the glow plug GP becomes equal to or higher than the keep temperature, the yes route of step S7 is circulated. Thereby, the glow plug GP is kept at least at the keep temperature while the engine is stopped.

  If the battery voltage becomes lower than the predetermined voltage during the circulation of steps S7, S8, S9, and S10, step S8 becomes no, and the notification means such as a lamp and buzzer installed in the cab toward the step S11 is activated. Then, it goes to step S12 and becomes a normal driving | operation. The normal operation here means that the glow plug GP is not energized.

  The case where step S8 is NO is a case where the pre-heating of the glow plug GP by the battery is continued for a long time without restarting the engine for a predetermined time due to the driver's convenience or electrical failure of the circuit. . In such a case, if energization from the battery to the glow plug is continued, the voltage of the battery decreases and it becomes difficult to restart the engine. For this reason, energization from the battery to the glow plug GP is stopped when the voltage of the battery is equal to or lower than a predetermined voltage.

  In this way, when the energization of the glow plug GP is stopped, the glow plug GP is cooled by heat radiation, so that it takes some time to restart. Therefore, in order to notify the driver of this, a notification means such as a lamp / buzzer provided in the cab is operated. Thereby, the driver | operator can know the cause of the discomfort by the start delay at the time of restart.

  However, since it is usually confirmed in step S4 that the driver is seated on the driver's seat, the battery is discharged below the predetermined voltage due to discharge to the heating element H during the circulation of steps S7, S8, S9, and S10. Before step S8 becomes NO, an engine restart signal is output, step S10 becomes YES, and the process often proceeds to step S13 in FIG.

  In step S13, a large amount of power is supplied from the battery to the glow plug GP. Thereby, the glow plug GP is heated to the keep temperature or higher.

  In step S14, it is determined whether the electrical resistance (temperature) of the glow plug GP is equal to or higher than a second predetermined value (starter operation appropriate temperature). The optimum starter operating temperature is higher than the keep temperature. If step S14 is NO, the process returns to step S13, and a large amount of power is supplied to the glow plug GP again, and steps S14 and S13 are circulated until step S14 becomes YES.

  If the answer to step S14 is yes, the process proceeds to step S15, where starter operation is permitted.

  Next, in step S16, it is determined whether the electrical resistance (temperature) of the glow plug GP is within a predetermined range (a temperature range suitable for starting / operation). In this predetermined range, the minimum value is set to be smaller than the second predetermined value in step S14, and the maximum value is set to be larger than the second predetermined value, and is set within a temperature range suitable for engine start / operation. Yes. If step S16 is YES, normal energization is performed to the glow plug GP in step S17, and normal operation is performed in step S20. As a result, the engine is started and operated.

  In step S16, when the electrical resistance of the glow plug GP is not within the predetermined range and is lower than the minimum value, the glow plug GP is energized more than usual in step S18. Thereby, the temperature rise of the glow plug GP is promoted. Then, returning to step S16, the circulation of steps S18 and S16 is performed until the electrical resistance (temperature) of the glow plug GP rises and falls within the predetermined range. The engine is started and the engine is started and operated.

  In step S16, when the electrical resistance of the glow plug GP is not within the predetermined range and is higher than the maximum value, the glow plug GP is energized in a smaller amount than usual in step S19. Thereby, the temperature rise of the glow plug GP is suppressed. Then, the process returns to step S16, and the circulation of steps S19 and S16 is performed until the electrical resistance (temperature) of the glow plug GP falls and falls within the predetermined range. The engine is started and the engine is started and operated.

  However, since the temperature of the glow plug GP is maintained at approximately the second predetermined value (starter operating temperature) in step S14, the engine normally starts from step S16 to step S17 and does not go to step S18 or step S19. . Steps S18 and S19 function during operation rather than when the engine is started. That is, during operation of the engine, the temperature of the glow plug GP is controlled within a predetermined temperature range suitable for fuel ignition during operation of the engine by steps S16, S17, S18, and S19.

  With this control, the present embodiment can exhibit the following effects.

<Reduced restart time>
When restart is predicted after the engine is temporarily stopped, the glow plug GP is preheated while the engine is stopped, and kept at a predetermined temperature lower than the optimum starter operating temperature (temperature suitable for restarting the engine). Therefore, when the temperature of the glow plug GP is raised to the optimum starter operating temperature when the engine is restarted, the temperature can be raised in a time that is comfortable for the driver (for example, about 0.1 second), and the engine restart delay is It is greatly suppressed. Since the restart time is shortened in this way, the engine can be restarted without a sense of incongruity for the driver.

  The pre-heating of the glow plug GP in step S9, which is performed to shorten the engine restart time, can be re-established in the near future after the engine is stopped only when the driver confirms that the driver is seated on the driver seat in step S4. It is predicted that there is a high possibility of starting. Therefore, it is possible to prevent wasteful preheating when the driver is away from the driver's seat and the possibility of restarting in the near future after the engine stops is low, and battery consumption can be suppressed.

  In step S8, when the battery is at a predetermined voltage or lower, the energization to the glow plug GP is cut off, so that the battery discharge can be suppressed and the engine restart can be prevented from being difficult due to the voltage drop. .

<Longer battery life>
In general, when restarting after the engine is stopped, a large amount of power is supplied from the battery to the glow plug GP in order to raise the glow plug GP to the optimum starting temperature in as short a time as possible. This may cause overdischarge to shrink. To elaborate on this point, when restarting the engine, a large amount of power is applied to the glow plug GP as described above, but the crankshaft is rotated in the latter half of the power input (or in parallel with the power input). For starter to drive. Here, the power consumption of the starter is generally very large.

  In this way, while a large amount of power is being supplied from the battery to the glow plug GP, since the starter with large power consumption must be driven by the battery, a very large load is applied to the battery, and the overall voltage of the battery is reduced. A decrease occurs, and sufficient power cannot be secured for each of the power input to the glow plug GP and the power input to the starter. For this reason, the arrival time until the glow plug GP rises to the optimum starting temperature is delayed, the rotation speed of the starter is reduced, and the actual compression pressure and compression temperature are reduced accordingly. This leads to an extension of the starter operation time, lengthens the time when the load is extremely large for the battery, and causes overdischarge to shorten the battery life.

  In the present embodiment, since the glow plug GP is preheated when the engine is restarted, a relatively small amount of power is supplied to the glow plug GP in order to raise the temperature of the glow plug GP to a temperature suitable for restart. It's enough. Therefore, a large amount of electric power to be supplied to the starter can be secured, the engine can be started by rotating the starter at a high speed at a stretch, and the operation time of the starter can be shortened. Therefore, the life of the battery can be extended.

<Improvement of reliability and durability of glow plug GP>
The glow plug GP has relatively high reliability and durability as long as it is continuously heated, but is relatively weak in the heat cycle of cooling and heating accompanying engine stop / restart. Moreover, it is weak also to the cold fuel etc. which are directly in contact with the heat generating body H heated red. Direct contact of fuel with the heating element H can be prevented by a shield S provided so as to cover the heating element H.

  On the other hand, regarding the thermal cycle of cooling and heating of the glow plug GP that accompanies the stop and restart of the engine, the glow plug GP is preheated when the restart after the engine stop is predicted. The reliability and durability of the glow plug GP can be increased.

  In particular, in a vehicle that employs an idle stop start mode system as in this embodiment, the cooling and heating of the glow plug GP frequently occurs when the engine is stopped and restarted. Although durability is a problem, as described above, by appropriately preheating the glow plug GP while the engine is stopped, the reliability and durability are significantly increased.

  The present invention is not limited to the above embodiment.

  For example, the present invention can be applied to a vehicle that does not include an idle stop start mode system. In this case, when the vehicle stops due to a signal waiting or traffic jam, the driver manually stops the engine manually and then restarts. The glow plug GP during the engine stop until the restart is shown in FIGS. 3 is preheated appropriately.

  The present invention can also be applied to a vehicle equipped with an idle stop start mode system even when the driver turns off the idle stop start switch in step S1. Also in this case, as in the previous stage, the driver manually stops the engine manually when the vehicle stops, and then restarts, but the glow plug GP is appropriately preheated according to FIGS. 2 and 3 while the engine is stopped. Thereafter, restarting can be easily performed in a short time.

  Further, in the present embodiment, a sensor that detects whether or not the driver is seated on the driving seat is provided, and it is predicted that the engine will be restarted in the near future when the seating is detected. However, even if the driver is not seated in the driver's seat, for example, when the driver turns on a button or switch provided in the driver's cab, a future restart will be possible after the engine stops even if the driver is away from the driver's seat. It may be predicted that it will be made. This is effective, for example, when a driver loads and unloads luggage away from a driving seat in a vehicle such as a truck.

  In addition, after the engine is stopped, the engine water temperature or the like changes depending on the stop time, the atmospheric temperature state, and the like, and the temperature of the glow plug GP optimal for restarting slightly changes. For this reason, a correction circuit for changing the energization pattern from the battery to the glow plug GP according to the stop time, the atmospheric temperature, the engine water temperature, or the like may be provided. As this correction circuit, for example, when the water temperature is relatively high and it can be determined that the restart is easy, a circuit that suppresses the amount of power to the glow plug GP can be considered.

  In addition, a certain amount of preliminary pressure is actually applied to the restarting fuel by an accumulator or the like, but this preliminary pressure is detected in advance, and the glow plug GP is detected depending on the magnitude of the preliminary pressure of the fuel (accumulator pressure). It is also conceivable to adjust the heat retention temperature (preheating temperature).

  In addition, the present invention is not limited to a natural gas direct injection type engine. When the engine is stopped and then restarted, a heat generating means such as a glow plug GP is heated to a temperature suitable for restarting. Applicable to engines that require operation.

It is the 1st explanatory view showing the control flow of the engine control device concerning one embodiment of the present invention. It is explanatory drawing which shows the control flow following FIG. FIG. 3 is an explanatory diagram showing a control flow continued from FIG. 2. It is sectional drawing of the cylinder head with which the glow plug GP as an exothermic means and the injector nozzle were mounted | worn. FIG. 5 is a view taken along line VV in FIG. 4.

Explanation of symbols

GP Glow plug as heat generation means S7 Step showing one function of control means S14 Step showing one function of control means S16 Step showing one function of control means S4 Step showing one function of prediction means

Claims (6)

Heating means as an ignition source used for starting the engine;
Control means for controlling the temperature of the heat generating means;
Predicting means for determining whether or not a prediction condition for restarting the engine after the engine is stopped during engine operation is satisfied,
The control means includes
It is determined whether or not the engine stop condition is satisfied while the engine is running, and the engine is stopped when the stop condition is satisfied,
When the engine is stopped in a state where the stop condition is satisfied and the prediction condition is satisfied by the prediction means, the temperature of the heat generating means is maintained at a predetermined temperature in preparation for engine restart. Engine control device. The heating means has a heating element connected to the battery and generates heat by electric resistance, and the control means stops energization from the battery to the heating element when the voltage of the battery is lower than a predetermined voltage. the engine control apparatus according to claim 1, wherein it is. The engine control apparatus according to claim 2, further comprising a notification means for notifying the driver of the stop of energization before the control means stops energization from the battery to the heating element . The engine control according to claim 2 or 3 , wherein the control means includes means for detecting an electric resistance of the heating element, and controls the temperature of the heating element based on an electric resistance value obtained by the means. apparatus. The engine according to any one of claims 1 to 4 , further comprising an engine automatic stop / restart means for temporarily stopping the engine under a predetermined stop condition and restarting the engine under a predetermined restart condition. Control device. The engine includes an engine control apparatus according to any one of claims 1 to 5, which is a natural gas direct injection type engine.

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