JP2005180291A - Internal combustion engine equipped with starter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine equipped with a starter capable of realizing stable combustion pressure for a long time, when the combustion pressure obtained by combusting fuel supplied at the time of stop of the engine is used for start of the engine. <P>SOLUTION: An ECU detects engine speed NE at the time of an expansion stroke accompanied by combustion pressure immediately after start of the engine, and determines whether or not the detected engine speed NE is within a range from a lower limit value NE1 of a predetermined reference engine speed to the upper limit value NE2. When the engine speed NE is within this range, since correction of fuel supply amount (injection amount) is unnecessary, the ECU completes this determination control. Meanwhile, when the engine speed NE is out of this range, since correction of the fuel supply amount is necessary, the ECU calculates correction amount. When performing engine stop control next time, the ECU corrects the fuel supply amount supplied to inside of a fuel chamber. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine equipped with a starting device.

  2. Description of the Related Art Conventionally, for example, a technique related to a so-called idling stop system is known in which an engine is stopped while a car is stopped while waiting for a signal, and the engine is restarted when the car is started. In such an idling / stop system, a technique is used in which fuel is supplied into the combustion chamber when the engine is stopped, and the combustion pressure obtained by burning the fuel is used for starting the engine when the engine is started next time. Is known (see, for example, Patent Documents 1 and 2).

Patent Documents 1 and 2 disclose techniques for reliably starting an engine by using an electric motor in an auxiliary manner even when the engine starting using combustion pressure is insufficient. Here, it is conceivable that the engine start is insufficient because the amount of fuel supplied to the combustion chamber when the engine is stopped is not an appropriate amount, and the combustion pressure is insufficient. However, paying attention to this point, there has been no technology for solving such problems.
Japanese Patent Laid-Open No. 2002-4985 JP-A-11-159374

  One of the objects of the present invention is to realize a stable combustion pressure over a long period of time when the combustion pressure obtained by burning the fuel supplied when the engine is stopped is used for starting the engine.

  One of the objects of the present invention is to smoothly start the engine over a long period of time.

  One of the objects of the present invention is to suppress power consumption when starting the engine.

  The present invention employs the following means in order to solve the above problems.

  That is, the present invention corrects the amount of fuel to be supplied into the combustion chamber when the engine is stopped next time when the engine speed is not appropriate immediately after the engine is started when the engine is started using the combustion pressure. I did it. That is, when the engine is started using the combustion pressure, the main reason why the engine speed immediately after the engine is started is not appropriate is that the combustion pressure is insufficient. The reason why the combustion pressure is insufficient is, for example, the amount of fuel required to be stored in the combustion chamber because various constituent members constituting the internal combustion engine change (deteriorate) with time. It can be considered that it changes over time.

  Therefore, according to the present invention, as described above, when the engine speed is not appropriate, the amount of fuel supplied into the combustion chamber at the next engine stop is corrected. Therefore, the next time the engine is started, an appropriate combustion pressure is obtained, and the engine speed immediately after the engine is started becomes appropriate.

In another invention, when the engine is started using combustion pressure, a phenomenon in which the engine speed immediately after the engine starts is not appropriate occurs a predetermined number of times (especially when a predetermined number of times occur continuously). On the other hand, it was determined that an abnormality occurred in the internal combustion engine.

As an internal combustion engine provided with a more specific starter of the present invention,
In an internal combustion engine provided with a starting device that can supply fuel to the combustion chamber when the engine is stopped and then use the combustion pressure obtained by burning the fuel when starting the engine to start the engine.
Detecting means for detecting an engine speed immediately after engine startup using the combustion pressure;
And a correction unit that corrects a supply amount of fuel supplied to the combustion chamber when the engine is stopped next time according to a detection result of the detection unit.

  According to the configuration of the present invention, it is possible to reflect the detection result of the engine rotation speed immediately after engine startup using combustion pressure in the amount of fuel supplied into the combustion chamber when the engine is stopped next time. Accordingly, it is possible to sequentially optimize the combustion pressure. Further, by optimizing the combustion pressure, it is possible to optimize the engine speed immediately after the engine is started, and it is possible to start the engine smoothly.

In addition, for the engine speed immediately after starting the engine, a reference speed having a lower limit value and an upper limit value is set,
When the engine speed immediately after engine startup detected by the detection means is below the lower limit value, the correction means performs a correction to increase the fuel supply amount,
When the engine speed immediately after the engine start detected by the detection means exceeds the upper limit value, the correction means may perform correction to reduce the fuel supply amount.

  As a result, when the engine speed immediately after the engine starts falls outside the range of the reference speed (between the lower limit value and the upper limit value), the amount of fuel supply is reduced so that the speed falls within this range. It is corrected. Accordingly, the engine speed immediately after the engine is started is optimized.

  Further, the correction means may perform correction only when the period from when the engine is stopped until when the engine is started next is within a predetermined range.

  That is, the appropriate values for the lower limit value and the upper limit value of the reference rotational speed vary depending on the period from when the engine is stopped until the next time the engine is started. That is, after the engine is stopped, the engine temperature is high for a while, and the air-fuel mixture is also kept as it is, so these appropriate values are almost constant. However, after a considerable amount of time has passed, the temperature of the engine decreases, the separation of the mixture into fuel and air proceeds, and further, the mixture or the separated fuel becomes a gap between the piston and cylinder, etc. As these leak out gradually, these appropriate values also fall. Therefore, when the lower limit value and the upper limit value are fixed values, when a considerable time has elapsed after the engine is stopped, correction is performed based on the lower limit value and the upper limit value. Therefore, if the correction is performed only when the period from the engine stop to the next engine start is within the predetermined range, the correction can be performed only when an accurate correction is possible.

  It is also preferable that the lower limit value and the upper limit value are fluctuating values that vary according to a period from when the engine is stopped to when the engine is next started. Alternatively, it is also preferable that the lower limit value and the upper limit value are fluctuating values that vary according to the temperature of the engine.

  That is, as described above, the appropriate values of the lower limit value and the upper limit value change depending on the elapsed time after the engine stops and the temperature of the engine. Therefore, these values can be optimized by changing the values according to the elapsed time and the engine temperature.

Moreover, it is good to provide the determination means which determines whether abnormality has generate | occur | produced in the internal combustion engine according to the correction condition containing the frequency | count of correction | amendment corrected by the said correction | amendment means.

  That is, if the cause of the inappropriate engine rotation speed immediately after engine startup is other than the combustion pressure or the fuel supply amount directly related to the combustion pressure, there is no point in correcting the fuel supply amount. In this case, it is considered that an abnormality such as a failure has occurred in various devices and various members constituting the engine. Therefore, if the engine speed does not become appropriate even if the fuel supply amount is corrected based on the correction status, it is preferable to determine that the engine speed is abnormal and to prompt outside inspection, for example. . As a preferable example of the correction situation, there is a case where the correction is continuously performed a certain number of times or more.

As another example of an internal combustion engine provided with a more specific starter of the present invention,
In an internal combustion engine provided with a starting device that can supply fuel to the combustion chamber when the engine is stopped and then use the combustion pressure obtained by burning the fuel when starting the engine to start the engine.
Detecting means for detecting an engine speed immediately after engine startup using the combustion pressure;
Determining means for determining whether or not an abnormality has occurred in the internal combustion engine in accordance with a detection situation including the number of times the value detected by the detecting means is out of a preset reference rotational speed range; The thing characterized by providing is mentioned.

  That is, the engine rotation speed immediately after engine start using the combustion pressure (detected value thereof) is a preset reference rotation speed range (which may be a fixed range or a variable range). It is considered that some abnormality has occurred in the engine when the occurrence of an accident frequently occurs, especially when the occurrence occurs continuously for a certain number of times or more. Therefore, in such a case, it is preferable to determine “abnormal” and, for example, prompt inspection outside. As a result, any abnormality in the engine is repaired, and as a result, it is possible to optimize the engine speed immediately after engine startup using the combustion pressure.

Further, in the internal combustion engine provided with any of the above-described starting devices,
It has an electric motor that rotates the crankshaft,
When the engine is stopped, fuel is stored in the combustion chamber in the middle of the compression stroke,
When starting the engine, it is preferable to burn the fuel when the crankshaft is rotated until the piston reaches the vicinity of top dead center by the electric motor.

  In addition, said each structure can be employ | adopted combining as much as possible.

  As described above, according to the present invention, when the combustion pressure obtained by burning the fuel supplied when the engine is stopped is used for engine starting, a stable combustion pressure can be realized over a long period of time. it can. As a result, the engine can be smoothly started over a long period of time. Furthermore, since a stable combustion pressure is realized, the dependency on the electric motor or the like is reduced when the engine is started, so that power consumption can be suppressed.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

With reference to FIGS. 1-9, the internal combustion engine provided with the starting device based on Example 1 of this invention is demonstrated.

<Overall structure of internal combustion engine provided with starter>
In particular, with reference to FIG. 1, the overall configuration of an internal combustion engine provided with a starting device will be described. FIG. 1 is a block diagram of an internal combustion engine provided with a starting device according to an embodiment of the present invention. In FIG. 1, an ECU (control means) that controls the system of each unit, various sensors, a power supply (battery), and wiring that electrically connects them are omitted.

  The internal combustion engine provided with the starting device according to the present embodiment includes an engine body 10 including a piston and a cylinder, a motor generator (MG) having a function of charging a battery and a function of generating a rotational driving force using charged electricity. ) 20, a starter 30 for starting the engine, a transmission 40 for converting engine power into torque or rotational speed corresponding to the load, and a crankshaft provided in the engine body 10 from the motor generator 20 or On the contrary, a belt 50 for transmitting a driving force is provided. The engine body 10 also includes a fuel injection valve 11 that injects fuel into the combustion chamber, an igniter (power transistor unit) 12 that drives an ignition coil, and the like.

<Idling stop system>
The internal combustion engine according to the present embodiment employs a so-called idling stop system that, for example, stops the engine while waiting for a signal and restarts the engine when starting the automobile. Yes. An example of the operation of the internal combustion engine when the idling / stop control is performed will be described with reference to FIGS. FIG. 2 is an explanatory diagram of the operation of the engine when performing idling / stop control. FIG. 3 is a flowchart showing an operation procedure of idling / stop control. In FIG. 2, 1 is a combustion chamber, 2 is a piston, 3 is a cylinder, 4 is an intake valve, 5 is an exhaust valve, 6 is a crankshaft, 7 is a rotating shaft of the motor generator 20, and 8 is a spark plug. In addition, 11 and 50 are a fuel injection valve and a belt, respectively, as described above.

  2A and 2B show how the engine is stopped. The operation control when the engine is stopped is performed by the ECU (step S200 in FIG. 3) when a predetermined engine stop condition is satisfied (step S100 in FIG. 3). Here, the predetermined stop condition can be selected, for example, from those listed below as appropriate, alone or in combination of two or more. That is, the vehicle speed has become zero, the shift lever has reached the neutral position (neutral) or the parking position (parking), the brake has been stepped on, the side brake has been activated, and the like.

  FIG. 2A shows the state of the engine immediately before the engine is stopped. When the engine is stopped, fuel is injected into the combustion chamber 1 by the fuel injection valve 11 with the intake valve 4 opened immediately before the engine stops. At this time, a rotational driving force by the motor generator 20 is appropriately applied to control the operation of the piston 2.

  FIG. 2B shows a state when the stop position of the piston 2 is controlled. The piston 2 is controlled by the motor generator 20 so as to be stopped at a position in the middle of the compression stroke. Specifically, the piston 2 is controlled to stop at a position where the crank angle is 60 to 90 degrees before the top dead center so that the torque required for restarting the engine is reduced.

2C and 2D show how the engine is restarted. The operation control at the time of restarting the engine is performed by the ECU (step S400 in FIG. 3) when a predetermined engine start condition (restart condition) is satisfied (step S300 in FIG. 3). Here, the predetermined engine starting conditions can be selected, for example, from those listed below as appropriate, alone or in combination of two or more. That is, the shift lever is moved forward or backward, the brake is released, the side brake is released, and the like.

  FIG. 2C shows the state of the engine immediately after engine restart. When the engine is restarted, piston 2 is driven by motor generator 20 to a position near top dead center.

  FIG. 2D shows the state of the engine after ignition is performed immediately after engine restart. As described above, the air-fuel mixture in the combustion chamber 1 is ignited by the spark plug 8 when the piston 2 is driven to a position near the top dead center by the driving force of the motor generator 20. When the air-fuel mixture is ignited, the air-fuel mixture in the combustion chamber 1 is combusted, and the piston 2 is driven by the combustion pressure. Therefore, thereafter, the piston 2 is driven by the normal combustion cycle without requiring the driving force by the motor generator 20.

  As described above, since the engine is automatically stopped when the vehicle is stopped, the fuel consumption can be reduced and the exhaust gas amount can be reduced. When the engine is restarted, the fuel supplied when the engine is stopped can be burned, and the combustion pressure can be used as the starting torque when starting the engine. can do. Therefore, the driver feels good when starting the vehicle. Also, less power is consumed than when the engine is restarted with only an electric motor such as the motor generator 20.

  In the multi-cylinder engine, the idling / stop control need not be performed for all the cylinders as shown in FIGS. For example, the control shown in FIGS. 2A to 2D is performed only for a cylinder that is predicted to be stopped in the middle of the piston from the bottom dead center to the top dead center (that is, during the compression stroke or the exhaust stroke) by stopping the engine. Just do it. Alternatively, the control shown in FIGS. 2A to 2D can be performed only for the specified cylinder by specifying one or more cylinders each time, such as changing the cylinder in turn every time the engine is stopped.

<Change over time of the appropriate amount of fuel stored in the combustion chamber when the engine is stopped>
As described above, the air-fuel mixture accumulated in the combustion chamber 1 is ignited when the engine is restarted. The combustion pressure obtained at this time and the engine rotation speed associated with the combustion pressure are roughly determined by the amount of fuel contained in the air-fuel mixture in the combustion chamber 1, that is, the amount of fuel supplied (injected) when the engine is stopped. Therefore, at the initial setting stage, the fuel supply amount is set so that a desired combustion pressure and engine speed can be obtained. However, when the internal combustion engine is used for a long period of time, the aging of the components (parts) of each part progresses, such as an increase in deposits. Therefore, even if fuel is supplied with the initially set fuel supply amount, the passage of time At the same time, the desired combustion pressure and engine speed cannot be obtained. That is, the appropriate amount of fuel that should be stored in the combustion chamber 1 when the engine is stopped changes over time. Therefore, in the internal combustion engine equipped with the starter according to the present embodiment, control is performed to appropriately correct the amount of fuel supplied into the combustion chamber 1 when the engine is stopped.

<Fuel supply amount (injection amount) correction>
In particular, the correction of the fuel supply amount (injection amount) supplied into the combustion chamber 1 when the engine is stopped will be described with reference to FIGS. FIG. 4 is a flowchart showing a control procedure for determining whether or not to correct the fuel supply amount. FIG. 5 is a graph showing the relationship between the engine speed immediately after engine startup and the indicated mean effective pressure. FIG. 6 is a graph showing the relationship between the fuel injection amount and the engine speed immediately after the engine is started. FIG. 7 is a graph showing the relationship between the elapsed time since the engine was stopped and the engine speed immediately after the engine was started, and the relationship between the elapsed time after the engine was stopped and the required injection amount. FIG. 8 is a graph showing the relationship between the elapsed time since the engine was stopped and the reference rotational speed. FIG. 9 is a graph showing the relationship between the engine temperature and the reference rotational speed.

<< Procedure for determining whether or not to correct the fuel supply amount (injection amount) >>
In particular, referring to FIG. 4, when the engine start control in the idling / stop control is performed, the amount of fuel supplied into the combustion chamber 1 is corrected when the engine stop control in the next idling / stop control is performed. The procedure for determining whether or not will be described.

  As described above, when the engine start condition is satisfied (step S300 in FIG. 3), engine start control is started (step S401). In the engine start control, as described above, when the piston 2 is driven to a position near the top dead center, the spark plug 8 is used to ignite the air-fuel mixture accumulated in the combustion chamber 1. The illustrated ECU controls (step S402, FIG. 2D). Then, the ECU detects the engine speed NE during the expansion stroke with the combustion pressure immediately after the engine is started (step S403, FIG. 2D). The ECU can detect the engine rotation speed NE using a known rotation sensor. Then, the ECU determines whether or not the detected engine rotational speed NE is within a range from a preset lower limit value NE1 to an upper limit value NE2 of the reference rotational speed (step S404). If the engine rotational speed NE is within this range, the ECU does not need to correct the fuel supply amount (injection amount), so the ECU ends this determination control. On the other hand, if the engine rotational speed NE is not within this range, the fuel supply amount (injection amount) needs to be corrected, so the ECU calculates the correction amount (step S405). Specifically, the ECU calculates a correction amount from the difference between the detected engine speed NE and the lower limit value NE1 or the upper limit value NE2.

  Thereafter, when the engine stop condition is satisfied (step S100 in FIG. 3), engine stop control is performed. In the engine stop control, as described above, fuel is injected into the combustion chamber 1 by the fuel injection valve 11 (FIG. 2A). At this time, the ECU performs control so that the fuel injection amount injected by the fuel injection valve 11 is corrected by the correction amount calculated in step S405.

  As described above, the detection result of the engine rotational speed NE immediately after engine startup using the combustion pressure can be reflected in the amount of fuel supplied into the combustion chamber when the engine is stopped next time. Accordingly, it is possible to sequentially optimize the combustion pressure. Further, by optimizing the combustion pressure, it is possible to optimize the engine rotational speed NE immediately after the engine is started, and it is possible to start the engine smoothly.

<< Reference speed of engine speed immediately after engine start using combustion pressure >>
The engine rotational speed NE during the expansion stroke with the combustion pressure immediately after the engine start is required to be a speed at which a desired indicated mean effective pressure can be obtained in order to start the engine appropriately. Therefore, in this embodiment, when the reference rotation speed is set in advance for the engine rotation speed NE and the engine rotation speed NE is not the reference rotation speed, the engine rotation speed NE is set to the reference rotation speed next time as described above. The fuel supply amount (injection amount) is corrected so that Hereinafter, the reference rotation speed will be described.

  FIG. 5 shows the relationship between the engine speed NE and the indicated mean effective pressure. In the figure, the position indicated by a black circle is the most ideal indicated mean effective pressure. Therefore, the initial setting is made aiming at the engine rotational speed at which the indicated mean effective pressure is obtained. Then, the reference rotational speed is determined so that the indicated mean effective pressure falls within a certain range around the ideal indicated mean effective pressure. That is, the reference rotation speed is a speed determined so as to be in a range from the lower limit value NE1 to the upper limit value NE2. In the figure, NE0 indicates the upper limit of the misfire region.

The engine speed NE is roughly determined by the fuel supply (injection) amount supplied when the engine is stopped. FIG. 6 shows the relationship between the fuel injection amount injected when the engine is stopped and the engine rotational speed NE. In the figure, a position indicated by a black circle is a position corresponding to the engine rotational speed at which the ideal indicated mean effective pressure is obtained. Therefore, the fuel injection amount that is injected when the engine is stopped is set to an initial setting value that is the fuel injection amount that provides the engine rotational speed. X1 and X2 are fuel injection amounts corresponding to the lower limit value NE1 and the upper limit value NE2, respectively. Therefore, if the fuel injection amount is in the range from X1 to X2, the engine speed NE is within the reference speed.

  However, the relationship between the fuel injection amount and the engine speed NE changes with time as described above. Therefore, since the relationship between the fuel injection amount and the engine rotational speed NE changes with time, a desired engine rotational speed cannot be obtained with the target fuel injection amount. Therefore, in the internal combustion engine according to this embodiment, As described above, control for correcting the fuel injection amount is performed.

  Here, the reference rotational speed described so far and the initial set values for the fuel injection amount for obtaining the reference rotational speed are values based on the average engine operating conditions. That is, the engine rotational speed NE for obtaining the ideal indicated mean effective pressure varies depending on the engine temperature and the elapsed time from the engine stop. Therefore, the initial set value is set assuming that the engine temperature immediately after the engine is stopped is an average temperature and the engine is restarted in a short period from the time when the engine is stopped. Therefore, even when the lower limit value NE1 and the upper limit value NE2 based on the initial setting values are fixed values, the effect of correcting the fuel injection amount can be obtained to some extent, but the temperature immediately after the engine stop is the average temperature. If the engine is far away or the engine is restarted after a long time has elapsed since the engine was stopped, a sufficient correction effect cannot be obtained. Therefore, it is possible to perform more effective correction by setting the lower limit value NE1 and the upper limit value NE2 to fluctuating values that vary depending on the driving situation or the like. Hereinafter, the case where the lower limit NE1 and the upper limit NE2 are changed will be described.

<< When the lower limit NE1 and the upper limit NE2 are changed >>
In particular, the case where the lower limit NE1 and the upper limit NE2 are changed will be described with reference to FIGS. In FIG. 7, it is originally required that the change of the reference rotation speed, which should be the basic reference, which changes according to the elapsed time since the engine is stopped, and the time which changes according to the elapsed time after the engine is stopped. The change of the fuel injection amount is shown.

  In the figure, a line L1 indicates a reference rotational speed (lower limit value NE1 and upper limit value) that should be a reference, which changes according to the elapsed time after the engine is stopped when the engine temperature immediately after the engine is stopped is 90 ° C. This is a transition of an ideal ideal rotational speed intermediate between the value NE2. Line L2 indicates a reference rotational speed (lower limit value NE1 and upper limit value NE2 that should be used as a reference), which changes according to the elapsed time since the engine was stopped when the engine temperature immediately after the engine stopped is 60 ° C. (Ideal reference rotation speed in the middle).

  Line L3 is the transition of the lower limit value of the fuel injection amount that is originally required and changes according to the elapsed time since the engine was stopped. Line L4 is a transition of the upper limit value of the fuel injection amount that is originally required, which changes according to the elapsed time since the engine was stopped. That is, if the amount of fuel injected in the engine stop control is in the region between the line L3 and the line L4, the mixture is appropriately combusted when the mixture is ignited in the engine start control. In the figure, F1 is an initial set value of the fuel injection amount.

  As described above, the reason why the reference rotational speed that should be the reference and the required fuel injection amount fluctuate depending on the engine temperature and the elapsed time from the engine stop will be briefly described.

First, the reason for fluctuations depending on the engine temperature is as follows. That is, depending on the temperature of the engine, the frictional resistance of the sliding portion in various moving parts constituting the engine changes. For this reason, even if the same combustion pressure is obtained with a certain amount of fuel injection, the engine speed will be different if the engine temperature is different. Therefore, when the engine temperature is different, the reference rotational speed to be used as a reference and the required fuel injection amount are also different.

  Moreover, the reason for fluctuating depending on the elapsed time since the engine stop is as follows. First, since the temperature of the engine decreases with the elapsed time from the engine stop, the reference rotational speed that should be the reference and the required fuel injection amount fluctuate for the above reasons. Secondly, separation of the air-fuel mixture into fuel and air proceeds with the passage of time since the engine stopped. Further, the air-fuel mixture and the separated fuel gradually leak from a gap between the piston and the cylinder, for example, with the passage of time. Therefore, the air-fuel ratio in the combustion chamber 1 changes with time. Therefore, even if a certain amount of fuel is injected, the air-fuel ratio in the combustion chamber 1 changes with the passage of time, so that the obtained combustion pressure differs depending on the ignition timing. From the above, when the elapsed time from the engine stop is different, the reference rotational speed to be used as a reference and the required fuel injection amount are also different.

  As can be seen from the above, the reference rotational speed does not mean that the combustion pressure for starting the engine properly can always be obtained if the engine rotational speed NE is the reference rotational speed. . In other words, the reference rotational speed means that when normal operation is performed (the temperature of the engine when the engine is stopped is not far from the average temperature, and the period from when the engine is stopped until the engine is restarted is too long) If not, it means the engine speed at which the engine is appropriately started. Therefore, if the engine temperature when the engine is stopped is far from the average temperature, or if a long time elapses from when the engine is stopped until the engine is restarted, the engine speed is appropriately started. It is not the engine speed necessary for the engine, but the engine speed corresponding to the situation.

  As can be seen from FIG. 7, the reference rotation speed that should be the reference is not changed during a certain period after the engine is stopped (until the vicinity of T1 in the figure), but thereafter decreases with the passage of time. It can also be seen that the higher the engine temperature, the higher the reference rotational speed that should be the reference. 8 and 9 show an example in which the lower limit value NE1 and the upper limit value NE2 of the reference rotation speed are changed. As shown in FIG. 8, the lower limit value NE1 and the upper limit value NE2 are not changed when the elapsed time from the engine stop is within a predetermined period, and may be changed so as to gradually decrease when the predetermined period is exceeded. . Further, as shown in FIG. 9, the lower limit value NE1 and the upper limit value NE2 are preferably changed so as to increase as the engine temperature increases. The lower limit value NE1 and the upper limit value NE2 may be changed only according to the elapsed time from the engine stop or may be changed only according to the engine temperature. It is more preferable to vary the temperature based on both.

  As described above, in the determination control shown in FIG. 4 described above, the lower limit value NE1 and the upper limit value NE2 of the reference rotation speed are set to fluctuating values that vary according to the elapsed time from the engine stop and the engine temperature. Therefore, it is possible to make an appropriate determination according to the situation, and to correct the fuel supply amount (injection amount) more accurately.

As can be seen from FIG. 7, when the lower limit value NE1 and the upper limit value NE2 of the reference rotation speed are fixed values, the fixed lower limit value NE1 and the upper limit value are fixed after a considerable time has elapsed since the engine stopped. Even if the fuel supply amount is corrected based on NE2, accurate correction cannot be made. Therefore, when the lower limit value NE1 and the upper limit value NE2 of the reference rotation speed are fixed values, the timing at which the engine is restarted is, for example, until the time T1 when the reference rotation speed that should be the reference is not changed. It is also preferable to perform the correction only when Even when the lower limit value NE1 and the upper limit value NE2 of the reference rotation speed are changed, after a considerable period of time has elapsed since the engine stopped, combustion does not occur even if ignition is performed at the start of the engine. It will be enough. Therefore, the engine rotation speed becomes very low, and it is difficult to set an effective reference rotation speed. Therefore,
Even when the lower limit value NE1 and the upper limit value NE2 are variable values, it is also preferable that the correction be executed only when the time when the engine is restarted is within a certain period from the engine stop.

  As described above, when correction is performed only during a predetermined period when the engine is restarted, it can be performed as follows, for example. That is, in the flowchart shown in FIG. 4, the period from when the engine stop condition is satisfied to when the engine start condition is satisfied is detected before step S404. Then, it is determined whether or not the detected period is within a predetermined period. Then, as a result of the determination, if it is within the predetermined period, the process proceeds to step S404, and if it is not within the predetermined period, the determination control shown in FIG.

<Abnormality judgment>
In the correction of the fuel supply amount described so far, various constituent members constituting the internal combustion engine change (deteriorate) with time, so that the required amount of fuel to be stored in the combustion chamber changes with time. It is assumed to be performed. However, if the cause of the inappropriate engine rotation speed immediately after engine startup is other than the combustion pressure or the fuel supply amount directly related to the combustion pressure, there is no point in correcting the fuel supply amount. That is, when the engine speed immediately after the engine start is not appropriate due to the occurrence of an abnormality such as a failure in various devices and various members constituting the engine, the above-described fuel supply amount (injection amount) There is no point in correcting the engine speed, and the engine speed cannot be made appropriate. Therefore, it is possible to determine whether or not any abnormality has occurred in the engine by using the correction status based on the correction control described above.

  That is, it is considered that some abnormality has occurred in the engine when the frequency of correction of the fuel supply amount is high, particularly when the correction is performed a plurality of times in succession. Therefore, for example, in the flowchart shown in FIG. 4 above, an abnormality determination is provided in which a counter for measuring the number of times of transition to step S405 is provided, and “abnormal” is determined when the routine proceeds to step S405 continuously. An apparatus (abnormality determination means) may be provided. If it is determined as “abnormal”, for example, it is possible to prompt the driver to perform inspections by emitting a light or sound that warns that some abnormality has occurred in the engine. Become.

  It is also preferable to divide the abnormality determination into two stages and perform different processes in the former stage process and the latter stage process. For example, when the process proceeds to step S405, a step of determining whether NE is smaller than NE3 (NE3 <NE1) is further provided. Here, NE3 is the minimum engine speed at which the engine can be started. When NE is less than NE3, there is a possibility that the engine cannot be started due to insufficient combustion pressure. Therefore, the ECU performs control so that normal cranking processing is performed immediately. This can prevent the engine from starting. In this way, it is possible to prevent the engine from being immediately disabled by performing normal cranking for the time being before it is determined to be abnormal.

  FIG. 10 shows a second embodiment of the present invention. In the first embodiment, in the engine start control in the idling / stop control, when the engine rotation speed immediately after the engine start falls outside the range of the reference rotation speed, the control for correcting the fuel supply amount in the next engine stop control is performed. Shown when to do. In the first embodiment, the control for determining whether or not any abnormality has occurred in the engine from the correction status is also shown.

In this embodiment, regardless of whether correction is performed or not, in the engine start control in the idling / stop control, it is detected whether or not the engine speed immediately after the engine start is within the range of the reference speed, and the detection is performed. The structure which performs control which determines whether some abnormality has generate | occur | produced in the engine from the condition is shown. Since the basic configuration of the internal combustion engine and the basic flow of idling / stop control are the same as those in the first embodiment, description thereof will be omitted. FIG. 10 is a flowchart showing a control procedure for determining whether any abnormality has occurred in the internal combustion engine.

  As described in the first embodiment, when the engine start condition is satisfied (step S300 in FIG. 3), the engine start control is started (step S501). In the engine start control, as described above, when the piston 2 is driven to a position near the top dead center, the spark plug 8 is used to ignite the air-fuel mixture accumulated in the combustion chamber 1. The illustrated ECU controls (step S502, FIG. 2D). Then, the ECU detects the engine speed NE during the expansion stroke with the combustion pressure immediately after the engine is started (step S503, FIG. 2D). The ECU can detect the engine rotation speed NE using a known rotation sensor. Then, the ECU determines whether or not the detected engine rotational speed NE is within a range from a preset lower limit value NE1 to an upper limit value NE2 of the reference rotational speed (step S504).

  If the engine rotational speed NE is within this range, the engine rotational speed is appropriate, and the ECU (not shown) resets a counter provided in the ECU (step S508). On the other hand, if the engine rotational speed NE is not within this range, the engine rotational speed is not appropriate, and therefore the ECU counts up a counter provided in the ECU (step S505). Next, the ECU determines whether or not the integrated count number counted by the counter exceeds a preset number C1 (step S506). If the accumulated count exceeds C1, the ECU determines that there is an abnormality (step S507). On the other hand, if the integrated count number does not exceed C1, the control for determining whether or not an abnormality has occurred is terminated. In this case, the count number of the counter is held.

  As described above, when it is continuously detected that the engine rotational speed NE during the expansion stroke accompanied by the combustion pressure immediately after engine startup is outside the range of the reference rotational speed more than C1 times, the engine It can be determined that some abnormality has occurred. And if it is determined as “abnormal”, for example, it is possible to urge the driver to check etc. by emitting a light or sound that warns that some abnormality has occurred in the engine, for example. Become. As a result, any abnormality in the engine is repaired, and as a result, it is possible to optimize the engine speed immediately after engine startup using the combustion pressure.

  It is also preferable to divide the abnormality determination into two stages and perform different processes in the former stage process and the latter stage process. For example, when the process proceeds to step S405, a step of determining whether NE is smaller than NE3 (NE3 <NE1) is further provided. Here, NE3 is the minimum engine speed at which the engine can be started. When NE is less than NE3, there is a possibility that the engine cannot be started due to insufficient combustion pressure. Therefore, the ECU performs control so that normal cranking processing is performed immediately. This can prevent the engine from starting. In this way, it is possible to prevent the engine from being immediately disabled by performing normal cranking for the time being before it is determined to be abnormal.

  Since the reference rotational speed is as described in the first embodiment, the description thereof is omitted (of course, the reference rotational speed may be a fixed value or a fluctuation value. The same as in the case of Example 1). Similarly to the case of the first embodiment, it is also preferable to perform the determination in step S504 only when the time when the engine is restarted is between the engine stop and a predetermined period. The reason is that if the time when the engine is restarted exceeds a predetermined period after the engine is stopped, it is difficult to set appropriate lower limit value NE1 and upper limit value NE2, and accurate determination becomes difficult.

(Other)
In each of the above-described embodiments, the port injection type internal combustion engine has been described as an example. However, the above-described various controls (fuel supply amount correction control and abnormality determination control) can also be applied to a cylinder injection type internal combustion engine. However, in this case, it goes without saying that there are some changes such as the timing of fuel injection when the engine is stopped. In this embodiment, when the engine is restarted, the crankshaft is slightly slightly turned up to the position near the top dead center by a motor (motor generator) first (a piston in the middle of the compression stroke). The case where the fuel (air mixture) accumulated in the combustion chamber is burned after being rotated is shown. However, in the various controls described in the present embodiment, various types of starting devices that use the combustion pressure obtained by burning the fuel supplied into the combustion chamber when the engine is stopped when the engine is restarted to start the engine. It can apply to the internal combustion engine provided with. For example, this implementation is also applied to a device that stores fuel in the combustion chamber in the middle of the expansion stroke and starts the combustion of the stored fuel without using an electric motor at all when the engine is restarted. Various controls described in the examples can be applied.

FIG. 1 is a block diagram of an internal combustion engine provided with a starting device according to an embodiment of the present invention. FIG. 2A is an explanatory diagram of the operation of the engine when performing idling / stop control (a view showing the state of the engine immediately before the engine is stopped). FIG. 2B is an explanatory view of the operation of the engine when performing idling / stop control (a diagram showing a state when controlling the stop position of the piston). FIG. 2C is an explanatory diagram of the operation of the engine when performing idling / stop control (a view showing the state of the engine immediately after the engine restart). FIG. 2D is an explanatory view of the operation of the engine when performing idling / stop control (a view showing the state of the engine after ignition is performed immediately after engine restart). FIG. 3 is a flowchart showing an operation procedure of idling / stop control. FIG. 4 is a flowchart showing a control procedure for determining whether or not to correct the fuel supply amount. It is a graph which shows the relationship between the engine speed immediately after engine starting, and the indicated mean effective pressure. FIG. 6 is a graph showing the relationship between the fuel injection amount and the engine speed immediately after the engine is started. FIG. 7 is a graph showing the relationship between the elapsed time since the engine was stopped and the engine speed immediately after the engine was started, and the relationship between the elapsed time after the engine was stopped and the required injection amount. FIG. 8 is a graph showing the relationship between the elapsed time since the engine was stopped and the reference rotational speed. FIG. 9 is a graph showing the relationship between the engine temperature and the reference rotational speed. FIG. 10 is a flowchart showing a control procedure for determining whether any abnormality has occurred in the internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Piston 3 Cylinder 4 Intake valve 5 Exhaust valve 6 Crankshaft 7 Motor generator rotating shaft 8 Spark plug 10 Engine body 11 Fuel injection valve 12 Igniter (power transistor unit)
20 Motor generator 30 Starter 40 Transmission 50 Belt

Claims (8)

In an internal combustion engine provided with a starting device that can supply fuel to the combustion chamber when the engine is stopped and then use the combustion pressure obtained by burning the fuel when starting the engine to start the engine.
Detecting means for detecting an engine speed immediately after engine startup using the combustion pressure;
An internal combustion engine comprising a starting device, comprising: a correcting unit that corrects a supply amount for supplying fuel into the combustion chamber when the engine is stopped next time according to a detection result of the detecting unit. For the engine rotation speed immediately after the engine is started, a reference rotation speed serving as a reference having a lower limit value and an upper limit value is set,
When the engine speed immediately after engine startup detected by the detection means is below the lower limit value, the correction means performs a correction to increase the fuel supply amount,
2. The correction unit according to claim 1, wherein when the engine rotation speed immediately after starting the engine detected by the detection unit exceeds the upper limit value, the correction unit corrects the fuel supply amount. Internal combustion engine equipped with a starting device.   The internal combustion engine with a starter according to claim 1 or 2, wherein the correction means performs correction only when a period from when the engine is stopped until when the engine is started next is within a predetermined range. organ.   The internal combustion engine with a starting device according to claim 2, wherein the lower limit value and the upper limit value are fluctuating values that vary depending on a period from when the engine is stopped until the next time the engine is started.   The internal combustion engine having a starting device according to claim 2, wherein the lower limit value and the upper limit value are fluctuating values that vary according to the temperature of the engine.   6. The apparatus according to claim 1, further comprising: a determination unit that determines whether an abnormality has occurred in the internal combustion engine according to a correction situation including the number of corrections corrected by the correction unit. An internal combustion engine comprising the starter described in 1. In an internal combustion engine provided with a starting device that can supply fuel to the combustion chamber when the engine is stopped and then use the combustion pressure obtained by burning the fuel when starting the engine to start the engine.
Detecting means for detecting an engine speed immediately after engine startup using the combustion pressure;
Determining means for determining whether or not an abnormality has occurred in the internal combustion engine in accordance with a detection situation including the number of times the value detected by the detecting means is out of a preset reference rotational speed range; An internal combustion engine provided with a starting device. It has an electric motor that rotates the crankshaft,
When the engine is stopped, fuel is stored in the combustion chamber in the middle of the compression stroke,
8. When starting the engine, the fuel is burned when the crankshaft is rotated until the piston reaches the vicinity of the top dead center by the electric motor. An internal combustion engine comprising the starting device described.

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