JP2007120448A - Vehicle engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle engine control device capable of inhibiting self-ignition of a mixture in restart and thereby protecting an engine when controlling automatic stop and automatic restart of the vehicle engine. <P>SOLUTION: The control device, in the idling stop control (automatic stop and restart control), stops the engine when engine water temperature Tw and engine intake air temperature Tin obtained are within a predetermined range and a stop condition is met (steps S102 to S105). When a restart condition is met during the stop of the engine, the engine is restarted (steps S113, S114). The engine water temperature Tw and the engine intake air temperature Tin are obtained during the stop of the engine and when these temperatures Tw, Tin obtained are within a self-ignition occurring range R, the engine is restarted immediately without waiting for formation of the next restart condition (S111, S112 and S114). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a vehicle engine that performs automatic stop / restart control.

  There is known an engine control system that performs so-called idle stop control in which an engine is automatically stopped when a vehicle is stopped due to traffic jams, waiting for a signal or the like, and noise, fuel consumption, and exhaust gas are suppressed when the vehicle is stopped. In such an engine control system, the engine is automatically stopped when the vehicle speed is zero and a stop condition such as the brake pedal being continuously depressed is satisfied. Further, after the engine is stopped, the engine is restarted when a restart condition such as release of the brake pedal depression operation is satisfied.

  In the invention described in Patent Document 1, it is determined whether or not the engine water temperature is within a predetermined range. If the engine water temperature is not within the predetermined range, automatic engine stop is prohibited. When the engine water temperature is relatively low, the engine is not automatically stopped because the startability cannot be ensured because the warm-up is not completed. Further, when the engine water temperature is relatively high, there is a risk of overheating, so automatic stop is not performed.

However, even if the engine water temperature is within the predetermined range, if the engine is automatically stopped when the vehicle is stopped, there is no running wind and the air cooling effect is small, or the cooling system using the power of the engine does not work sufficiently As a result, the temperature of the engine and the surrounding atmosphere increases. Then, when restarting the engine, the temperature of the air-fuel mixture introduced into the combustion chamber of the engine increases. Then, as the temperature of the air-fuel mixture rises, its pressure increases and self-ignition occurs during the compression stroke. If self-ignition occurs, the combustion pressure becomes higher than that of normal combustion, which may damage the engine. In addition, when the engine speed increases, there is a problem that the vibration of the vehicle increases or the vehicle shock at the time of starting increases.
JP 58-18535 A

  An object of the present invention is to provide a vehicular engine that can suppress the occurrence of self-ignition of an air-fuel mixture at the time of restarting and thereby protect the engine when performing automatic stop and automatic restart control of the vehicle engine. It is to provide a control device.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  According to the first aspect of the present invention, a self-ignition occurrence region is defined by using engine temperature information as a parameter, the temperature information is acquired, and it is determined whether or not the value of the acquired temperature information is within the self-ignition occurrence region. To do. And when it determines with it being in the self-ignition generation | occurrence | production area | region during an engine automatic stop, an engine is restarted immediately.

  In an engine control apparatus that performs automatic stop / restart control, the engine is automatically stopped when a predetermined stop condition is satisfied, and then the engine is restarted when the restart condition is satisfied. Here, paying attention to the state in which the engine is automatically stopped, the cooling system or the like does not work sufficiently while the engine is stopped, and the temperature of the engine and the surrounding atmosphere rises. When the temperature of the air-fuel mixture rises and the pressure becomes excessively high at the time of restart, self-ignition occurs. For this reason, if an auto-ignition occurrence area is set based on the possibility (probability) of the occurrence of auto-ignition using the engine temperature information as a parameter, and the value of the temperature information acquired while the engine is stopped is within the auto-ignition occurrence area The engine is immediately restarted without waiting for the establishment of the next restart condition. As a result, the occurrence of self-ignition is suppressed, and as a result, abnormal vibration and noise due to self-ignition and excessive increase in engine rotation speed can be suppressed, and the engine can be protected.

  According to a second aspect of the present invention, in the first aspect of the invention, when the acquired temperature information value is within the self-ignition generation region, the engine start time control amount is corrected upon restart.

  According to the inventors, the possibility of self-ignition and the magnitude of the combustion pressure at the time of self-ignition can be affected by the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber, the charging efficiency, etc. It has been confirmed. Therefore, if the acquired temperature information value is within the auto-ignition generation region, the engine is restarted by adjusting the air-fuel ratio of the air-fuel mixture and the charging efficiency by correcting the control amount at the time of engine start. Let Thereby, generation | occurrence | production of self-ignition is suppressed more reliably. Further, even if self-ignition occurs, the combustion pressure can be reduced, so that damage to the engine is reduced.

  In the invention according to claim 3, in the invention according to claim 2, the temperature information is used as a parameter to determine a self-ignition determination region where the possibility of occurrence of self-ignition is different, and the acquired temperature information value is any It is determined whether or not it is within the self-ignition determination region. And if it exists in the self-ignition generation | occurrence | production area | region where generation | occurrence | production of self-ignition is comparatively high, an engine will be restarted immediately. Further, when the engine is in the self-ignition generation region where the possibility of self-ignition is relatively low, the engine start time control amount is corrected upon restart.

  According to the above configuration, when the possibility of self-ignition is low, the engine stop state is continued until the restart condition is satisfied, and the engine control amount is corrected while the restart condition is satisfied while the engine control amount is corrected. Is restarted. Further, when the possibility of self-ignition becomes high, the engine is restarted immediately. Thereby, generation | occurrence | production of self-ignition can be suppressed by an appropriate means, ensuring the advantage which suppresses the noise by an automatic stop, fuel consumption, and exhaust gas.

  In the invention according to claim 4, a self-ignition occurrence region is defined with the engine temperature information as a parameter, the temperature information is acquired, and it is determined whether or not the value of the acquired temperature information is within the self-ignition occurrence region. To do. And when it determines with it being in the self-ignition generation | occurrence | production area | region at the time of restart conditions being satisfied, the engine start time control amount is correct | amended in the case of restart.

  As described above, according to the inventors, the possibility of self-ignition and the combustion pressure at the time of self-ignition are affected by the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber, the charging efficiency, etc. Has been confirmed. For this reason, a self-ignition occurrence region based on the possibility (probability) of the occurrence of self-ignition is set using the temperature information of the engine as a parameter, and the value of the temperature information acquired when the restart condition is satisfied is within the self-ignition occurrence region. For example, the air-fuel ratio of the air-fuel mixture and the charging efficiency thereof are adjusted by correcting the control amount at engine start, and the engine is restarted. As a result, the occurrence of self-ignition is suppressed, and as a result, abnormal vibration and noise due to self-ignition and excessive increase in engine rotation speed can be suppressed, and the engine can be protected. Further, even if self-ignition occurs, the combustion pressure is reduced, so that engine damage is reduced.

  According to a fifth aspect of the invention, in the invention according to any one of the second to fourth aspects, the amount of fuel injected by the fuel injection valve is corrected to be increased as a correction of the starting control amount.

  When the amount of fuel in the mixture is increased, the temperature of the mixture decreases due to the latent heat of vaporization of the fuel. Thereby, since possibility that self-ignition will generate | occur | produce falls, generation | occurrence | production of self-ignition can be suppressed.

  According to a sixth aspect of the invention, in the invention according to any one of the second to fifth aspects, the engine start time control amount is corrected so as to reduce the actual compression ratio or the amount of air-fuel mixture in the engine cylinder. .

  Decreasing the actual compression ratio in the engine cylinder avoids excessively high pressure of the mixture. Further, if the filling amount of the air-fuel mixture is decreased, it is possible to avoid the air-fuel mixture charging efficiency from being reduced and the pressure of the air-fuel mixture to become excessively high. Therefore, the occurrence of self-ignition can be suppressed.

  According to a seventh aspect of the invention, in the sixth aspect of the invention, a variable valve mechanism capable of adjusting the opening / closing operation of at least one of the intake valve and the exhaust valve is provided, and the intake valve or the exhaust is used as a correction of the control amount at the start. The valve closing timing is corrected to the retard side, or the lift amount of the intake valve is corrected to decrease.

  By correcting the closing timing of the intake valve to the retard side, the air-fuel mixture once introduced into the combustion chamber is blown back into the intake passage. By correcting the closing timing of the exhaust valve to the retard side, the air-fuel mixture once introduced into the combustion chamber is blown into the exhaust passage. Further, by reducing the lift amount of the intake valve, the amount of the air-fuel mixture introduced into the combustion chamber is reduced. According to the above, since the filling amount of the air-fuel mixture is reduced and the filling efficiency is lowered, the occurrence of self-ignition can be suppressed.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, at least one of a temperature of engine cooling water or a temperature of intake air is acquired, and the acquired temperature is generated by auto-ignition. It is determined whether it is within the area.

  As described above, the cause of the occurrence of self-ignition is that the temperature of the air-fuel mixture rises. For this reason, the possibility of the occurrence of self-ignition is accurately determined by acquiring the temperature of the engine that affects the temperature rise of the air-fuel mixture and the temperature of the surrounding atmosphere and determining whether or not it is within the self-ignition determination region. .

  According to a ninth aspect of the invention, in the invention according to any one of the first to eighth aspects, temperature information when the engine is automatically stopped is acquired as initial temperature information. And temperature information is estimated from the acquired initial temperature information and the elapsed time from the time of an engine automatic stop.

  After the engine stops, the value of temperature information changes with time. At this time, it is possible to estimate a change in the value of temperature information after the engine is stopped based on the initial temperature and the elapsed time when the engine is stopped. For this reason, it is possible to estimate the temperature information until the next restart during the automatic stop, and determine the possibility of occurrence of self-ignition based on the estimated temperature information.

  According to a tenth aspect of the present invention, in the invention according to any one of the first to ninth aspects, the engine is automatically activated when the intake air temperature acquired when the stop condition is satisfied is higher than a predetermined value. Don't stop.

  When the temperature of the intake air is higher than a predetermined value when the stop condition is satisfied, there is a high possibility that the value of the temperature information enters the auto-ignition generation region due to the subsequent temperature rise. Therefore, in such a case, automatic stop is prohibited. One of the direct causes of the occurrence of self-ignition is the temperature of the air sucked into the combustion chamber, and the possibility of self-ignition occurs because the engine is not automatically stopped based on the temperature of the intake air. Can be judged appropriately.

(First embodiment)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In this embodiment, an engine control system is constructed for a multi-cylinder gasoline engine as a vehicle engine. In this control system, an electronic control unit (hereinafter referred to as ECU) is used as a center to control the fuel injection amount and to perform ignition. The timing will be controlled. First, an overall schematic configuration diagram of the engine control system will be described with reference to FIG.

  In the engine 10 shown in FIG. 1, an air cleaner 12 is provided at the most upstream portion of the intake pipe 11, and an air flow meter 13 for detecting the intake air amount is provided downstream of the air cleaner 12. The air flow meter 13 incorporates an intake air temperature sensor 13a for detecting the temperature of intake air (engine intake air temperature). A throttle valve 14 whose opening degree is adjusted by a throttle actuator 15 such as a DC motor is provided on the downstream side of the air flow meter 13. The opening degree of the throttle valve 14 (throttle opening degree) is detected by a throttle opening degree sensor built in the throttle actuator 15. The intake pipe 11 is connected to the intake port of each cylinder on the downstream side of the throttle valve 14, and an electromagnetically driven fuel injection valve 16 that injects fuel in the vicinity of each intake port is attached.

  An intake valve 17 and an exhaust valve 18 are provided at an intake port and an exhaust port of the engine 10, respectively. An intake valve variable device 17 a is provided at the cam portion of the intake valve 17. The intake valve variable device 17a has, for example, a hydraulic cam phase adjustment mechanism, and adjusts the opening / closing timing of the intake valve 17 by continuously setting the cam shaft phase of the intake valve 17 to be variable. is there.

  The air-fuel mixture is introduced into the combustion chamber 19 by the opening operation of the intake valve 17, and the exhaust gas after combustion is discharged to the exhaust pipe 21 by the opening operation of the exhaust valve 18. A spark plug 22 is attached to each cylinder of the cylinder head of the engine 10, and a high voltage is applied to the spark plug 22 at a desired ignition timing through an ignition device (igniter) (not shown) composed of an ignition coil or the like. Applied. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 22, and the air-fuel mixture introduced into the combustion chamber 19 is ignited and used for combustion.

  A water jacket 24 is formed in the cylinder block 23 as a cooling system. Cooling water circulates through the water jacket 24 by driving a water pump (not shown) that uses the power of the engine 10 to cool the engine 10. Further, the engine 10 is provided with a starter motor 25 as a starting device.

  The exhaust pipe 21 is provided with a catalyst 26 such as a three-way catalyst for purifying CO, HC, NOx and the like in the exhaust gas, and the air-fuel ratio of the air-fuel mixture with exhaust gas as a detection target is located upstream of the catalyst 26. An air-fuel ratio sensor 31 (an O2 sensor, a linear A / F sensor, etc.) for detecting the above is provided. Further, the cylinder block 23 of the engine 10 is supplied with a crank angle sensor 32 that outputs a rectangular crank angle signal at every predetermined crank angle of the engine 10 (for example, every 30 ° CA cycle), and a cooling water temperature (engine water temperature). An engine water temperature sensor 33 to be detected is attached. In addition to this, a vehicle speed sensor 34 for detecting a traveling speed (vehicle speed), an accelerator opening sensor 35 for detecting an accelerator operation amount (accelerator opening) by a driver, and a brake operation (ON or OFF switch operation by a driver). ) Is provided.

  The outputs of the various sensors described above are input to the ECU 40 that controls the engine. The ECU 40 is composed mainly of a well-known microcomputer comprising a CPU, ROM, RAM, etc., and executes various control programs stored in the ROM, thereby controlling the fuel injection amount and ignition timing according to the engine operating state. Implement air volume control.

  Further, the ECU 40 performs automatic stop / restart control (hereinafter referred to as idle stop control). In the idle stop control, when the vehicle is stopped due to a signal waiting or traffic jam, the vehicle speed is zero, the accelerator opening is zero, and the brake switch signal is on. When the stop condition is satisfied, the engine 10 is automatically activated. Stop. Further, after the engine 10 is stopped, the brake switch signal is turned off as a restart condition. When the restart condition is satisfied, the engine 10 is restarted. Here, as the stop condition, in addition to the above condition, it may be considered that a predetermined time elapses after the vehicle speed becomes zero. In addition to the above conditions, it is conceivable that the accelerator opening is given by the driver's operation as the restart condition. Furthermore, it is conceivable that each condition is variably set according to the driving situation.

  By the way, when the engine 10 is automatically stopped, the temperature of the engine 10 and the surrounding atmosphere rises because there is no running wind and the air cooling effect is small, or the cooling system using the power of the engine 10 does not work sufficiently. To do. Further, since air is trapped in the intake pipe 11, the engine intake temperature rises due to the high-temperature ambient atmosphere. For this reason, the air-fuel mixture becomes hot when the engine 10 is restarted. The pressure of the air-fuel mixture that has become high becomes high, and the possibility of occurrence of self-ignition in the combustion stroke increases.

  FIG. 2 shows how the pressure in the cylinder changes during normal times and when self-ignition occurs. When self-ignition occurs, the combustion pressure increases compared to normal combustion. This is because, in normal combustion, the air-fuel mixture is ignited by the spark plug 22 and the flame surface spreads, whereas in the combustion when self-ignition occurs, combustion is also performed outside the flame surface. It is. Therefore, the engine 10 may be damaged.

  Therefore, in the present embodiment, a self-ignition occurrence region is set with the temperature information of the engine 10 as a parameter, and if the value of temperature information acquired from various sensors is within the self-ignition occurrence region, the following restart condition is satisfied. Without waiting for establishment, the engine 10 is restarted immediately.

  FIG. 3 is a map showing an example of the relationship between the engine water temperature Tw, the engine intake air temperature Tin, and the self-ignition generation region R. In FIG. 3, the high temperature side of the boundary line L is set as the self-ignition generation region R. The boundary line L is set based on the possibility (probability) that self-ignition occurs. The possibility that self-ignition occurs at a higher temperature side than the boundary line L is high, and the possibility that self-ignition occurs at a low temperature side. Is low. Moreover, it is considered that the possibility that self-ignition occurs increases as the temperature increases. In the present embodiment, as the boundary line L, a curve is set through which the engine water temperature Tw passes α = 105 ° C. and the engine intake air temperature Tin passes β = 40 ° C.

  FIG. 4 is a flowchart showing a processing procedure of idle stop control. In this idle stop control, in addition to the conventional automatic stop and restart control, the engine 10 is forcibly restarted when the possibility of the occurrence of self-ignition increases due to the temperature rise during engine stop. This process is executed by the ECU 40 at predetermined time intervals (25 msec in this embodiment).

  In step S101, it is determined whether or not the engine 10 is stopped. If the engine 10 is not stopped, the process proceeds to step S102 and processing for automatic stop is performed. On the other hand, if the engine 10 is stopped, the process proceeds to step S111 and processing related to restart is performed.

  First, in step S102 as a process for automatic stop, an engine coolant temperature Tw and an engine intake air temperature Tin are acquired from various sensors. In step S103, it is determined whether or not the acquired engine water temperature Tw and engine intake air temperature Tin are within a predetermined range (in this embodiment, 75 <Tw <105 and Tin <40 ° C.). If it is within the predetermined range, the process proceeds to step S104, and if it is not within the predetermined range, the present process is terminated. In this step, it is determined whether or not the engine water temperature Tw is lower than a predetermined value (Tw: about 75 ° C.), thereby avoiding that the engine 10 is automatically stopped before the warm-up of the engine 10 is completed and the restartability is deteriorated. Yes. Further, by determining whether the engine water temperature Tw and the engine intake air temperature Tin are not higher than predetermined values (Tw: about 105 ° C., Tin: about 40 ° C.), the engine 10 may overheat or self-ignition When the possibility of occurrence of this is high, automatic stop is not performed and the engine 10 is protected.

  In step S104, it is determined whether the aforementioned stop condition is satisfied. If the stop condition is satisfied, the fuel injection is stopped in step S105 and the engine 10 is stopped. On the other hand, if the stop condition is not satisfied, the present process is terminated as it is.

  Next, a process for restarting when it is determined in step S101 that the engine 10 is stopped will be described. In step S111, engine water temperature Tw and engine intake air temperature Tin are acquired from various sensors. In step S112, it is determined whether or not the acquired engine water temperature Tw and engine intake air temperature Tin are within the self-ignition generation region R. If it is not within the self-ignition generation region R, the process proceeds to step S113. If it is within the self-ignition generation region R, the process proceeds to step S114.

  In step S113, it is determined whether or not the aforementioned restart condition is satisfied. If the restart condition is satisfied, the process proceeds to step S114, and if not, the process ends.

  In step S114, cranking is performed by driving the starter motor 25, and the engine is started. Here, the restart process of the engine 10 in this step is performed when the engine coolant temperature Tw and the engine intake air temperature Tin are within the auto-ignition generation region R in step S112 in addition to when the restart condition in step S113 is satisfied. Also do. That is, the engine 10 is restarted when the possibility of the occurrence of self-ignition increases without waiting for the establishment of the next restart condition.

  Now, when the accelerator opening becomes zero during operation of the engine 10 and the vehicle speed becomes zero with the brake switch signal turned on, the engine 10 is stopped by the idle stop control of FIG. Then, since the vehicle speed is zero, the air cooling effect by the traveling wind is reduced, and the cooling system does not work sufficiently. For this reason, the temperature of the engine 10 and the surrounding atmosphere rises, and the engine water temperature Tw and the engine intake air temperature Tin start to rise. At this time, when the engine water temperature Tw and the engine intake air temperature Tin are within the self-ignition generation region R, the engine 10 is restarted even if the brake switch signal is not turned on.

  As described above, according to the embodiment described in detail, the following excellent effects can be obtained.

  (1) After the engine 10 is automatically stopped, when the temperature information values (engine water temperature Tw and engine intake air temperature Tin) acquired from various sensors are within the auto-ignition generation region R, the engine 10 is immediately restarted. Thus, the engine 10 is restarted when the possibility of the occurrence of self-ignition increases without waiting for the establishment of the next restart condition, and the occurrence of self-ignition during the restart is avoided. Even if self-ignition occurs, the combustion pressure is reduced as compared with the case where restart is performed after the restart condition is satisfied, so that damage to the engine 10 is reduced. As a result, the engine is protected, and it is possible to prevent the vibration of the vehicle from increasing when the engine speed increases and the vehicle shock at the start of the vehicle from increasing.

  (2) A self-ignition generation region R using the engine water temperature Tw and the engine intake air temperature Tin as parameters is set as engine temperature information, and it is determined whether or not the acquired temperature information is within the self-ignition generation region R. The possibility of the occurrence of self-ignition can be accurately determined by setting the self-ignition occurrence region R from the parameter that affects the temperature rise of the air-fuel mixture that is the cause of the occurrence of self-ignition.

  (3) When the engine water temperature Tw and the engine intake air temperature Tin are larger than the predetermined values, the engine 10 is not automatically stopped even when the stop condition is satisfied. As a result, the engine 10 is more reliably prevented from being stopped when the possibility of self-ignition is high compared to the case where the automatic stop is not performed based only on the engine water temperature Tw, and the engine 10 is automatically The occurrence of ignition is avoided.

(Second Embodiment)
According to the inventors, it has been confirmed that the possibility of self-ignition and the magnitude of the combustion pressure are affected by the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber. The leaner the stoichiometric air / fuel ratio, the higher the possibility of self-ignition and the higher the combustion pressure at the time of self-ignition. Therefore, when there is a high possibility that self-ignition occurs at the time of restart, the occurrence of self-ignition is suppressed by increasing the amount of fuel injected by the fuel injection valve 16. This is because the temperature of the air-fuel mixture decreases due to the latent heat of vaporization of the injected fuel, and the pressure decreases.

  The idle stop control process executed by the ECU 40 in the first embodiment is changed to that shown in FIG. In the processing of the idle stop control shown in FIG. 5, when the air-fuel mixture is likely to self-ignite when the restart condition is satisfied, the amount of fuel injected from the fuel injection valve 16 is increased and corrected, and the engine 10 is restarted. Start. In FIG. 5, the same processes as those in FIG. 4 are denoted by the same step numbers and used as they are, and the following description will focus on the differences.

  If the engine 10 is not stopped in step S101, processing for automatic stop is performed in steps S102 to S105. That is, if the engine water temperature Tw and the engine intake air temperature Tin are within the predetermined ranges and the stop condition is satisfied, the engine 10 is stopped.

  On the other hand, when the engine 10 is stopped in step S101, the process proceeds to step S201 to perform processing related to restart. First, in step S201, it is determined whether a restart condition is satisfied. If the restart condition is satisfied, the process proceeds to step S202. If the restart condition is not satisfied, the present process is terminated. Subsequently, in step S202, an engine water temperature Tw and an engine intake air temperature Tin are acquired. In step S203, it is determined whether or not the engine water temperature Tw and the engine intake air temperature Tin are within the self-ignition generation region R. If it is within the self-ignition generation region R, the process proceeds to step S204, and if it is not within the self-ignition generation region R, the process proceeds to step S205.

  In step S204, the amount of fuel injected by the fuel injection valve 16 is corrected as the self-ignition suppression control. The amount of fuel injected when the engine 10 is started is obtained in advance as a table (not shown) based on the engine water temperature Tw. In this step, the amount of fuel to be injected is increased by multiplying the amount of fuel calculated from the table by a correction coefficient. In general, when self-ignition occurs, self-ignition occurs over several times of ignition. Therefore, in this step, correction is performed so as to be applied over that number of times. Further, the correction coefficient may be a variable value based on the engine intake air temperature Tin in addition to a constant value. In the case of a variable value, it becomes possible to more appropriately calculate the amount of fuel necessary to avoid the occurrence of self-ignition.

  In step S125, the engine 10 is restarted. At this time, when the engine water temperature Tw and the engine intake air temperature Tin are not within the self-ignition generation region R, the fuel amount obtained in advance is injected from the fuel injection valve 16, and when it is within the self-ignition generation region R The corrected amount of fuel is injected and the engine 10 is restarted.

  As described above, according to the embodiment described in detail, the following excellent effects can be obtained.

  When the restart condition is satisfied when the engine 10 is stopped, if the engine water temperature Tw and the engine intake air temperature Tin at that time are within the self-ignition generation region R, the amount of fuel injected by the fuel injection valve 16 is corrected to be increased. 10 is restarted. As a result, the temperature of the air-fuel mixture decreases due to the latent heat of vaporization of the fuel, and the occurrence of self-ignition is suppressed. Further, even if self-ignition occurs, the combustion pressure is reduced, so that damage to the engine 10 is reduced. As a result, similarly to the effect (1) in the first embodiment, the engine is protected, and when the engine speed increases, the vibration of the vehicle increases and the vehicle shock at the start increases. It is prevented.

  Further, the effects (2) and (3) in the first embodiment can be obtained at the same time.

  The present invention is not limited to the embodiment described above, and may be implemented as follows.

  In the first embodiment, the engine 10 is restarted immediately when the engine water temperature Tw and the engine intake air temperature Tin are within the self-ignition generation region R, but the starting control amount is corrected at the time of restart. . As a result, the air-fuel ratio of the air-fuel mixture, the charging efficiency, and the like, which are the causes of self-ignition, are adjusted, and the occurrence of self-ignition is more reliably suppressed. Further, even if self-ignition occurs, the combustion pressure is reduced, so that damage to the engine 10 is reduced.

  In the second embodiment, in the auto-ignition suppression control process of step S204 in the idle stop control of FIG. 5, the increase correction of the amount of fuel injected by the fuel injection valve 16 is performed as the correction of the start time control amount. The following correction may be performed. According to experiments by the inventors, it has been confirmed that the possibility of self-ignition is affected by the charging efficiency in addition to the air-fuel ratio of the air-fuel mixture introduced into the combustion chamber 19. This is because the higher the filling efficiency, the higher the pressure of the air-fuel mixture. Therefore, if the engine water temperature Tw and the engine intake air temperature Tin are within the self-ignition generation region R when the restart condition is satisfied, the closing timing of the intake valve 17 by the intake valve variable device 17a is set in the self-ignition suppression control process of step S204. Correct to the retarded angle side. As a result, the air-fuel mixture is blown back into the intake passage of the engine 10 and the charging efficiency of the air-fuel mixture introduced into the combustion chamber 19 is reduced, thereby avoiding the occurrence of self-ignition.

  In addition, the intake valve variable device 17a includes, for example, several types of cams having different shapes, and the lift amount of the intake valve 17 can be adjusted by appropriately switching the cams by hydraulic operation or the like. Then, in the self-ignition suppression control process of step S204 in the idle stop control of FIG. 5, the lift amount of the intake valve 17 by the intake valve variable device 17a is reduced and corrected. As a result, the amount of air-fuel mixture introduced into the combustion chamber 19 is reduced, and the occurrence of self-ignition is avoided by reducing the charging efficiency.

  Further, as another configuration, an exhaust valve variable device is provided in the cam portion of the exhaust valve 18 so that the opening / closing timing of the exhaust valve 18 can be adjusted. Then, in the self-ignition suppression control process of step S204 in the idle stop control of FIG. 5, the closing timing of the exhaust valve by the exhaust valve variable device is corrected to the retard side. As a result, a part of the air-fuel mixture introduced into the combustion chamber of the engine 10 is blown into the exhaust pipe 21, and the charging efficiency of the air-fuel mixture introduced into the combustion chamber 19 is reduced, thereby avoiding the occurrence of self-ignition. Is done.

  In the above embodiment, the self-ignition generation region R is set as shown in FIG. 3, and it is determined whether or not the acquired engine water temperature Tw and engine intake air temperature Tin are within the self-ignition generation region R. You may carry out. As shown in FIG. 6, two self-ignition generation regions R1 and R2 are set as the self-ignition generation regions. The self-ignition generation regions R1 and R2 are set as the high temperature side of the boundary lines L1 and L2, and the boundary lines L1 and L2 are set based on different possibilities (probabilities) of the occurrence of self-ignition. Here, it is assumed that the possibility of self-ignition increases as the respective temperatures increase in the order of the low temperature side of the boundary line L1, the boundary lines L1 and L2, and the high temperature side of the boundary line L2. In this case, the boundary lines L1 and L2 are curves passing through the engine water temperature Tw α1 and α2 and the engine intake air temperature Tin passing through β1 and β2, and are set such that α1 <α2 and β1 <β2. If the restart condition is satisfied while the engine 10 is stopped, and the engine water temperature Tw and the engine intake air temperature Tin at that time are within the auto-ignition generation region R1, the fuel injection valve 16 and the like are corrected as a correction of the control amount at the start. The engine 10 is restarted after correcting the control amount. On the other hand, if the engine water temperature Tw and the engine intake air temperature Tin acquired while the engine 10 is stopped are within the auto-ignition generation region R2, the engine 10 is immediately restarted without waiting for the next restart condition to be satisfied. . As described above, when the possibility of the occurrence of self-ignition is low, the occurrence of self-ignition is avoided by correcting the starting control amount. Further, when the possibility of the occurrence of self-ignition becomes high, the engine 10 is started immediately, so that the occurrence of self-ignition is more reliably suppressed by appropriate means.

  In the above embodiment, the self-ignition occurrence region is determined based on the engine water temperature Tw and the engine intake air temperature Tin, but the present invention is not limited to this. Since the increase in various temperatures after the engine 10 stops increases with a correlation with each other, any temperature may be noted. It is also possible to use outside air or the temperature in the engine room as temperature information. Furthermore, it is also possible to obtain information that can indirectly estimate engine temperature information such as atmospheric pressure or intake pressure, and determine whether or not the estimated temperature information value is within the auto-ignition occurrence region.

  In addition to acquiring temperature information such as the engine water temperature Tw and the engine intake air temperature Tin each time and determining whether or not the vehicle is in the self-ignition generation region R, the following may be performed. Temperature information at an arbitrary time is estimated from the temperature information (initial temperature) when the engine 10 is stopped and the elapsed time since the stop, and it is determined whether or not the estimated temperature information is within the self-ignition generation region R. . Since the temporal change of the temperature information depends on the initial temperature and the elapsed time, the possibility of the occurrence of self-ignition can be estimated based on the estimated information. For example, the calculation load of the ECU 40 can be reduced by obtaining a time at which the temperature reaches a predetermined temperature, setting a timer interrupt, and appropriately controlling restart of the engine 10 using the timer interrupt.

It is a whole lineblock diagram showing an outline of an engine control system. It is a figure which shows the mode of the change of the cylinder internal pressure at the time of normal time and self-ignition generation | occurrence | production. It is a map which shows the relationship between the engine water temperature Tw, the engine intake air temperature Tin, and the self-ignition generation area R. It is a flowchart which shows the process of the idle stop control in 1st Embodiment. It is a flowchart which shows the process of idle stop control in 2nd Embodiment. It is a map which shows the relationship between engine water temperature Tw and engine intake temperature Tin, and self-ignition generation | occurrence | production area | region R1, R2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Intake pipe, 13a ... Intake temperature sensor as acquisition means, 16 ... Fuel injection valve, 17 ... Intake valve, 17a ... Intake valve variable device as valve variable mechanism, 25 ... Starter motor, 33 ... Acquisition Engine water temperature sensor as means, 40... ECU as judgment means, control means, and correction means.

Claims (10)

The present invention is applied to a spark ignition type vehicle engine, and automatically stops the engine when a predetermined stop condition is satisfied, and restarts the engine when a predetermined restart condition is satisfied. In the control device,
Obtaining means for obtaining temperature information of the engine;
A determination unit that determines a self-ignition occurrence region using the temperature information as a parameter, and determines whether or not the value of the temperature information acquired by the acquisition unit is within the self-ignition generation region;
Control means for immediately restarting the engine when the determination means determines that the engine is in the self-ignition occurrence region during the automatic stop of the engine;
A control device for a vehicle engine comprising:   2. The vehicle according to claim 1, further comprising a correction unit that corrects the engine start-time control amount when restarting when the determination unit determines that the vehicle is within the self-ignition determination range. 3. Engine control device.   The determination unit determines a self-ignition determination region having a different possibility of occurrence of self-ignition using the temperature information as a parameter, and the value of the temperature information acquired by the acquisition unit is within any one of the self-ignition determination regions. The control means restarts the engine immediately when it is determined by the determination means that the possibility of the occurrence of self-ignition is within a relatively high self-ignition occurrence region, The correction means corrects the engine start-time control amount at the time of restart when it is determined by the determination means that it is within a self-ignition occurrence region where the possibility of occurrence of self-ignition is relatively low. The vehicle engine control device according to claim 2. The present invention is applied to a spark ignition type vehicle engine, and automatically stops the engine when a predetermined stop condition is satisfied, and restarts the engine when a predetermined restart condition is satisfied. In the control device,
Obtaining means for obtaining temperature information of the engine;
A determination unit that determines a self-ignition occurrence region using the temperature information as a parameter, and determines whether or not the value of the temperature information acquired by the acquisition unit is within the self-ignition generation region;
Correction means for correcting the engine start-time control amount at the time of restart when the determination means determines that the engine is in the self-ignition generation region when the restart condition is satisfied;
A control device for a vehicle engine, comprising:   The vehicle engine control apparatus according to claim 2, wherein the correction unit corrects the amount of fuel injected by the fuel injection valve to be increased as a correction of the control amount at the time of starting.   6. The vehicle according to claim 2, wherein the correction means corrects the start time control amount so as to reduce an actual compression ratio or an air-fuel mixture filling amount in a cylinder of the engine. Engine control device.   A variable valve mechanism capable of adjusting the opening / closing operation of at least one of the intake valve and the exhaust valve is provided, and the correction means sets the closing timing of the intake valve or the exhaust valve by the variable valve mechanism as a correction of the control amount at the time of starting. The vehicle engine control device according to claim 6, wherein the vehicle engine control device corrects to a retarded angle side or corrects the lift amount of the intake valve to decrease.   The acquisition unit acquires at least one of a temperature of the engine cooling water or a temperature of the intake air of the engine as the temperature information, and the determination unit acquires the temperature of the cooling water or the intake air acquired by the acquisition unit. The vehicle engine control apparatus according to any one of claims 1 to 7, wherein it is determined whether or not the temperature of the engine is within a self-ignition occurrence region.   The acquisition means acquires the temperature information when the engine is automatically stopped as initial temperature information, and estimates temperature information from the acquired initial temperature information and an elapsed time since the engine is automatically stopped. A control device for a vehicle engine according to any one of claims 1 to 8.   10. The vehicle engine control device according to claim 1, wherein the engine is not automatically stopped when the temperature of the intake air acquired when the stop condition is satisfied is higher than a predetermined value. .

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