JP2004036561A - Automatic stop / start system for in-cylinder injection internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic stopping and starting device for an internal combustion engine having a longer idle stop time while securing a quick startability of the engine when restarting. <P>SOLUTION: The automatic stopping and starting device for a cylinder injection type internal combustion engine automatically stops and starts an internal combustion engine 1 when predetermined conditions are met. The automatic stopping and starting device is structured so that when the fuel pressure detected by a fuel pressure detecting means 14 while the internal combustion engine 1 is stopped becomes less than the predetermined pressure, fuel is injected into a cylinder positioned in the compression stroke and/or a cylinder for the next compression stroke while keeping the internal combustion engine 1 in a stopped state, and when conditions for restarting is established, fuel is injected into a cylinder in a suction stroke. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an automatic stop / start device for a direct injection internal combustion engine, which is particularly suitable for use in an idle stop vehicle.
[0002]
[Prior art]
In recent years, in order to reduce emissions and improve fuel economy, the engine is automatically stopped when a predetermined stop condition is satisfied (idle stop), and then automatically restarted when a predetermined restart condition is satisfied. Idle stop vehicles have been put to practical use.
[0003]
Also, in-cylinder injection type internal combustion engines (in-cylinder injection type engines) that inject fuel directly into the combustion chamber have been put into practical use for the purpose of reducing emissions and improving fuel efficiency. In this in-cylinder injection engine, there are two modes of operation: a uniform combustion mode in which fuel is injected in the intake stroke to form a uniform mixture in the combustion chamber, and a fuel injection around the ignition plug by injecting fuel in the compression stroke. A stratified combustion mode that realizes a super-lean air-fuel ratio as a whole while forming an air-fuel mixture in the vicinity of the air-fuel ratio. The mode can be appropriately switched. Further, by applying such an in-cylinder injection type engine to the above-described idle stop vehicle, it is possible to further improve fuel efficiency and emission.
[0004]
By the way, in such an idle stop vehicle, a quick restart is required at the time of restarting the engine. However, a direct injection type engine is particularly suitable for an idle stop vehicle in that such a quick restart is possible. ing. That is, in a direct injection engine, by injecting fuel into a cylinder that is in a compression stroke at the time of starting, the engine can be started earlier than an engine that injects fuel in a general intake stroke. Incidentally, the start of the engine by the compression stroke injection is disclosed in, for example, JP-A-10-30468.
[0005]
[Problems to be solved by the invention]
However, in the starting by the compression stroke injection, as shown in FIG. 7, the starting torque (average effective pressure shown) decreases as the fuel pressure (hereinafter, referred to as fuel pressure) decreases, so that the restartability deteriorates in the low fuel pressure state. Resulting in. Therefore, when a direct injection engine is applied to a vehicle having an engine automatic stop / start function, such as an idle stop vehicle or a hybrid vehicle, in order to obtain a quick start effect, even if the engine is idle-stopped, the fuel is always kept to some extent. Pressure is required.
[0006]
On the other hand, when the engine is stopped, the high-pressure pump for pressurizing the fuel is stopped, so that the fuel pressure gradually decreases. Therefore, it is conceivable to provide a sensor for detecting the fuel pressure and automatically restart the engine when the fuel pressure drops to a lower limit pressure within a range in which the engine can be quickly started. However, there is a problem that the advantage of the idle stop cannot be sufficiently exhibited.
[0007]
The present invention has been made in view of such a problem, and has been made to automatically stop an in-cylinder injection type internal combustion engine in which the idle stop time can be made as long as possible while ensuring quick startability of the engine at the time of restart. It is intended to provide a starting device.
[0008]
[Means for Solving the Problems]
Therefore, the automatic stop and start device for a direct injection internal combustion engine of the present invention according to claim 1 automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied and the internal combustion engine when a predetermined restart condition is satisfied. A fuel pressure detecting means for detecting a pressure of fuel supplied to a fuel injection valve of the internal combustion engine, and detecting a cylinder position of the internal combustion engine during automatic stop. When the fuel pressure detected by the fuel pressure detecting means during the automatic stop of the internal combustion engine becomes equal to or lower than a predetermined pressure, the cylinder positioned in the compression stroke with the internal combustion engine stopped and / or the next compression stroke And a start control means for injecting fuel into the cylinder located in the intake stroke when the restart condition is satisfied.
[0009]
Therefore, if the fuel pressure drops below a predetermined pressure during automatic stop, fuel is injected into the cylinder located in the compression stroke and / or the next cylinder in the compression stroke while the internal combustion engine is stopped. Even if the starting condition is satisfied and fuel can be substantially injected only in the intake stroke, the fuel is first supplied to the cylinder located in the compression stroke and / or the cylinder that will be the next compression stroke, so that the first ignition is performed. In the case of two or more cylinders, the compression stroke injection can be executed substantially, and quick start can be performed. For this reason, the automatic stop period in which quick start is possible can be lengthened, and fuel consumption can be further reduced while quick start is enabled.
[0010]
Preferably, the start control means is located in a compression stroke when the restart condition is satisfied in a state where the fuel pressure detected by the fuel pressure detection means exceeds the predetermined pressure during the automatic stop of the internal combustion engine. The fuel is injected into a cylinder and / or a cylinder which is to be subjected to a next compression stroke. With this configuration, it is possible to surely promptly restart the internal combustion engine in a state where the fuel pressure is high.
[0011]
Further, it is preferable that the injection amount of the fuel injection performed while the internal combustion engine is stopped is determined according to the stop crank angle. With this configuration, an appropriate amount of fuel can be injected according to the piston stop position of the cylinder into which fuel is injected.
Further, it is preferable that the start control means prohibits the fuel injection in the compression stroke for a predetermined period after the start and continues the fuel injection in the intake stroke. According to such a configuration, since the compression stroke injection is prohibited in a state where the fuel pressure is low, it is possible to prevent the operation of the engine from becoming unstable after the start of the internal combustion engine.
[0012]
Further, the start control means may be configured to inject fuel into the cylinder located in the compression stroke and the cylinder to be the next compression stroke while the engine is stopped. According to such a configuration, even when the fuel pressure is low, the two cylinders that are initially ignited at the time of restart can substantially execute the compression stroke injection, and the engine can be reliably and quickly automated.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an automatic stop / start device for a direct injection internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a configuration of a main part thereof. As shown in the figure, the engine 1 is configured as a direct injection engine (direct injection internal combustion engine) that directly injects fuel into a combustion chamber, and an injector (fuel injection valve) (not shown) faces the combustion chamber. Is established. In this in-cylinder injection engine, there are two modes of operation: a uniform combustion mode in which fuel is injected in the intake stroke to form a uniform mixture in the combustion chamber, and a fuel injection around the ignition plug by injecting fuel in the compression stroke. A stratified combustion mode that realizes a super-lean air-fuel ratio as a whole while forming an air-fuel mixture in the vicinity of the air-fuel ratio. The mode can be appropriately switched.
[0014]
An intake passage 2 and an exhaust passage 3 are connected to a combustion chamber of the engine 1.
Among them, an air cleaner 6 and a throttle valve 7 are provided in the intake passage 2 in order from the upstream side, and a surge tank 2a is further provided downstream thereof. Further, the exhaust passage 3 is provided with an exhaust purification catalytic converter and a muffler (muffler) not shown.
[0015]
The throttle valve 7 is a so-called drive wire type throttle valve (ETV) electrically connected to the accelerator pedal, and has an opening degree according to the engine operating state other than the accelerator pedal depression amount of the driver. It has been changed. The fuel supply system is provided with an engine-driven high-pressure pump (not shown) that pressurizes the fuel to a pressure sufficiently higher than the in-cylinder pressure during the compression stroke injection.
[0016]
The engine 1 has an air flow sensor 11 for detecting an intake air amount, a throttle opening sensor (TPS) 12 for detecting an opening of a throttle, and a crank angle sensor for detecting an engine speed by detecting a crank angle. (Engine speed sensor) 13, a cam angle sensor (not shown) for detecting a rotation state of a camshaft, a fuel pressure sensor (fuel pressure detecting means) 14 for detecting a fuel pressure, and an accelerator opening for detecting a driver's accelerator pedal opening. A degree sensor (not shown) and the like are provided. In this embodiment, the fuel pressure sensor 14 is provided in a fuel supply system between the high-pressure pump and the injector, and the fuel pressure sensor 14 detects the fuel pressure after pressurization by the high-pressure pump. .
[0017]
These sensors are connected to a controller (ECU) 20. The ECU 20 sets an operation mode of the engine 1 based on information from these sensors, and operates control signals for the throttle valve 7, the injector, the ignition coil, and the like. Is set.
Further, a vehicle (not shown) equipped with the engine 1 automatically stops the operation of the engine 1 (idle stop or automatic stop) when a predetermined engine stop condition is satisfied, and thereafter sets a predetermined engine restart condition. Is established as an idle stop vehicle that automatically starts (restarts) the engine 1 when.
[0018]
Next, the main part of the present invention will be described. As shown in FIG. 1, the ECU 20 includes a cylinder discriminating unit 21 that detects a cylinder position of the engine 1 that is automatically stopped, and a start control unit 22 that controls operations of an injector, a starter motor, an ignition coil, and the like. . When the condition for automatically stopping the engine 1 is satisfied, the cylinder discriminating means 21 starts compression of the stopped engine 1 based on the crank angle signal and the TOP signal detected by the crank angle sensor 13 and the cam angle sensor immediately before the engine is stopped. The cylinder in the stroke is determined, and the piston position is determined.
[0019]
Thereafter, when the fuel pressure detected by the fuel pressure sensor 14 during the automatic stop of the engine 1 becomes equal to or lower than a predetermined pressure, the "cylinder in the current compression stroke" and the "next compression stroke" determined by the cylinder determination means 21 are performed. Fuel is injected into the two cylinders “cylinder” while the engine 1 is stopped. Further, when the restart condition of the engine 1 is satisfied thereafter, fuel is injected into the cylinder located in the intake stroke. The operation of such an injector is controlled by the start control means 22.
[0020]
That is, when the fuel pressure decreases to a predetermined pressure during the idle stop, first, fuel is injected in advance to the cylinder in the compression stroke and the cylinder to be the next compression stroke, and the idle stop state is maintained. Then, when the engine restart condition is satisfied, the engine 1 is restarted by the intake stroke injection.
[0021]
This is because the engine 1 can be restarted as quickly as possible when the engine is restarted, and the idle stop state is maintained even a little until the restart condition is satisfied. That is, as described above, in the direct injection engine, by injecting fuel in the compression stroke at the time of starting, the engine 1 can be started earlier than the engine that injects fuel in the general intake stroke. In the starting by the stroke injection, the starting torque decreases as the fuel pressure decreases (see FIG. 7). Therefore, if the idle stop state continues for a long time, the startability deteriorates as the fuel pressure decreases. In this case, it is conceivable that the engine is automatically restarted when the fuel pressure drops to the lower limit of the range in which the engine 1 can be quickly started. In this case, the engine 1 is restarted even if the idle stop condition is satisfied. As a result, the idle stop time is shortened as a result.
[0022]
Therefore, in the present invention, as described above, when the fuel pressure becomes equal to or lower than the predetermined pressure, fuel is previously injected into the cylinder in the compression stroke and the cylinder in the next compression stroke. As a result, at the time of restart, the two cylinders that are initially ignited have at least substantially the same fuel injection as the compression stroke injection, and a quick engine restart can be performed without starting the engine 1 when the idle stop condition is satisfied. It can be realized. If the restart condition is satisfied before the fuel pressure becomes equal to or lower than the predetermined pressure, fuel is injected into the cylinder in the compression stroke to restart the engine (that is, restart is performed by the compression stroke injection). Has become. Further, in the present embodiment, the predetermined fuel pressure is set to a lower limit pressure in a fuel pressure range (see FIG. 7) in which quick engine start can be performed.
[0023]
Further, in this case, when the engine is restarted, the compression stroke injection cannot be executed for the cylinders after the first two cylinders due to a decrease in fuel pressure, so that the intake stroke injection is performed.
By the way, since the high-pressure pump for pressurizing the fuel is driven by the engine 1, the fuel pressure increases when the engine 1 is restarted. Therefore, after the engine is restarted, if it is detected that the fuel pressure detected by the fuel pressure sensor 14 has risen to a pressure at which the compression stroke can be injected, the fuel pressure depends on the operating state of the driver (or the engine operating state) detected from various sensors Thus, the compression stroke injection or the intake stroke injection is performed. Further, regardless of the information from the fuel pressure sensor 14, after a predetermined period (predetermined time) has elapsed, it may be considered that the pressure has increased to the pressure at which the compression stroke can be injected.
[0024]
On the other hand, when the fuel pressure becomes equal to or lower than the predetermined pressure when the engine 1 is stopped, the injection amount of the fuel injected into the cylinder in the compression stroke and the cylinder in the next compression stroke is, for example, a map as shown in FIG. In accordance with the stop crank angle. Here, in FIG. 2, the horizontal axis is the stop crank angle (BTDC), and the vertical axis is the pulse width of the injector, that is, the fuel injection amount.
[0025]
In a cylinder in which the stop crank angle is within a predetermined range (in this embodiment, a range from BTDC0 to 60 ° as shown in FIG. 2), that is, a cylinder in the latter half of the compression stroke, fuel injection is performed even if the cylinder is stopped in the compression stroke. The quantity is zero, so that no fuel is injected.
This is because in the latter half of the compression stroke, although the in-cylinder pressure is maintained at a high pressure immediately after the engine is stopped, the in-cylinder pressure gradually decreases while the engine 1 is stopped, and the air amount decreases. This is because it is possible. In this case, if the in-cylinder pressure is reduced to a value equivalent to the atmospheric pressure, an air amount necessary for starting cannot be secured, and an effective starting torque cannot be obtained even if ignition is performed. Therefore, in the meaning of the present embodiment, even if the cylinder is in the compression stroke, the fuel is not injected when the stop crank angle is in the predetermined range in the latter half of the compression stroke as described above.
[0026]
Further, between BTDC 60 ° and 180 °, the fuel injection amount is set so as to be proportional to the crank angle (that is, the fuel injection amount is set according to the stroke position of the piston). . This is because if the inside of the cylinder is completely closed as described above, the air amount in the cylinder will be constant regardless of the piston position, but in reality the cylinder pressure will gradually decrease, so the piston stroke position The fuel injection amount is set assuming that the corresponding amount of air exists in the cylinder.
[0027]
On the other hand, although it is not strictly a compression stroke, fuel injection is also performed for a cylinder stopped in the latter half of the intake stroke immediately before the compression stroke. This is to compensate for the above-described setting of the fuel injection amount of the cylinder in the latter half of the compression stroke to 0. Further, the fuel injection amount at this time is set to a constant value irrespective of the crank angle as shown in FIG.
[0028]
In the present embodiment, the latter half of the intake stroke refers to BTDC 180 ° to 240 °. Therefore, in the present embodiment, when the fuel pressure detected by the fuel pressure sensor 14 becomes equal to or lower than the predetermined pressure during the automatic stop of the engine 1, the cylinder in the BTDC 60 ° to 240 ° determined by the cylinder determining unit 21 is set to the “current compression stroke”. At the same time, and fuel is injected into the two cylinders of the "cylinder in the current compression stroke" and the "cylinder in the next compression stroke" while the engine 1 is stopped. I have.
[0029]
The automatic stop / start device for a direct injection internal combustion engine according to one embodiment of the present invention is configured as described above, and its operation will be described below with reference to a time chart of FIG. First, when a predetermined idle stop condition (stop condition) such as detection that the accelerator pedal depression amount (APS) of the driver is fully closed by an accelerator opening sensor (not shown) is satisfied (t = t) ₁ At this point, the power supply to the ignition plug of the engine is cut off and the engine 1 stops (t = t). ₂ ).
[0030]
Since the high-pressure pump for pressurizing the fuel is also stopped when the engine is stopped, the pressure of the fuel remaining in the fuel supply system downstream of the high-pressure pump also starts to gradually decrease. Then, when it is detected or determined that the fuel pressure has become equal to or lower than a predetermined pressure (fuel injection determination fuel pressure during idling stop), the cylinder (BTDC 60 ° to 240 °) in the current compression stroke determined by the cylinder determining means 21 and Next, fuel injection is performed on the cylinders that are to undergo a compression stroke while the engine is stopped (t = t). ₃ ). The fuel injection amount at this time is set according to the crank angle by using the map shown in FIG.
[0031]
Then, when a predetermined restart condition is satisfied (t = t ₄ ), The engine 1 is restarted by the intake stroke injection. At this time, since fuel has already been injected into the two cylinders that are initially in the compression stroke, even if the intake stroke injection is performed, the first two cylinders are substantially started by the compression stroke injection, and the engine is started quickly. be able to.
[0032]
Further, when it is determined that the fuel pressure has risen to a fuel pressure at which compression stroke injection is possible (compression injection start determination fuel pressure) (t = t) ₅ Thereafter, the compression stroke injection or the intake stroke injection is executed according to the operating state of the engine 1. Note that t ₅ Since the switching control of the operation mode thereafter is known, the description will be omitted.
FIG. 4 shows a time chart when the restart condition is satisfied before the fuel pressure becomes equal to or lower than the predetermined pressure. Note that the condition for stopping the engine 1 is satisfied (t = t ₁ ), The engine 1 stops (t = t) ₂ The description up to) is the same as the description using FIG.
[0033]
After the engine is stopped, the pressure of the fuel remaining in the fuel supply system also starts to gradually decrease with the stop of the high-pressure pump. However, if the restart condition is satisfied before the fuel pressure falls below a predetermined pressure (t = t ₄ ') In this case, the engine 1 is restarted by the compression stroke injection because the fuel pressure is as high as possible to execute the compression stroke injection. Thus, the engine can be started quickly. In this case, the completion of the start of the engine is determined based on information such as the engine speed, or after a predetermined period has elapsed (t = t ₅ ′) Thereafter, compression stroke injection or intake stroke injection is executed according to the operating state of the engine 1.
[0034]
FIGS. 5 and 6 are flowcharts for briefly explaining the operation of the present invention. When the engine 1 is idle-stopped, the idle-stop routine shown in FIG. 5 is executed. That is, in step S1, the fuel pressure is acquired from the fuel pressure sensor 14, and in step S2, it is determined whether the fuel pressure has become equal to or lower than a predetermined pressure. If the fuel pressure is higher than the predetermined pressure, the routine returns. If the fuel pressure is equal to or lower than the predetermined pressure, the process proceeds to step S3 to determine whether the fuel injection during the idle stop has already been performed. Further, when it is determined in step S3 that the fuel injection is not performed, the process proceeds to step S4, and the fuel injection amount for the cylinder in the compression stroke is set based on the stop crank angle. Then, in step S5, fuel injection is executed for the cylinder in the compression stroke and the cylinder in the next compression stroke, and the process returns.
[0035]
Then, the above-described routines of steps S1 to S5 are repeatedly executed at predetermined intervals until the restart condition of the engine 1 is satisfied or the main key is turned off.
On the other hand, when the restart condition of the engine 1 is satisfied, the routine shown in FIG. 6 is executed. That is, when a cranking start (engine start) is executed in step S11, the process proceeds to step S12, and it is determined whether fuel injection has already been executed during the idle stop. If it is determined that the fuel injection has been performed during the idle stop, the process proceeds to step S13, in which the intake stroke injection is performed. In step S14, it is determined that the fuel pressure has become the fuel pressure at which the compression stroke can be injected in step S14. Execute until judged. That is, when fuel injection is performed in advance during idle stop, the engine is started by intake stroke injection. Step S14 may be a step for determining whether or not a predetermined period has elapsed.
[0036]
If it is determined in step S12 that the fuel injection has not been performed during the idle stop, the process proceeds to step S15 to execute the compression stroke injection, and the compression stroke injection is determined in step S16 to determine whether the engine has been started. Repeat until
That is, when fuel injection is not executed during the idle stop, the engine is started by the intake stroke injection.
[0037]
Then, after step S14 and step S10, the process proceeds to step S17, and the engine operation mode is switched between the compression stroke injection mode and the intake stroke injection mode according to the engine operation state such as the fuel pressure and the load.
Therefore, according to the present invention, when the fuel pressure drops below the predetermined pressure during the idle stop, the cylinders located in the compression stroke (the cylinders at BTDC 60 ° to 240 °) while maintaining the idle stop and the cylinders that will be the next compression stroke Even if the restart condition is satisfied after the fuel pressure drops, the fuel is first supplied to the cylinder located in the compression stroke and the cylinder that will be the next compression stroke, so that the fuel is first ignited. In the two cylinders, the compression stroke injection can be performed substantially, and the engine 1 can be started quickly. For this reason, the automatic stop period in which the engine 1 can be started quickly can be lengthened, and fuel consumption can be further reduced while the engine can be started quickly.
[0038]
Further, since the injection amount of the fuel injection performed in the idle stop state is determined according to the stop crank angle, an appropriate fuel amount can be injected according to the piston stop position of the cylinder into which fuel is injected. Therefore, the startability can be further improved.
Further, after the engine 1 is started, the fuel injection in the compression stroke is prohibited and the fuel injection in the intake stroke is continued until the fuel pressure becomes a pressure at which compression injection can be performed or until a predetermined period has elapsed. The compression stroke injection is not executed, and the operation can be prevented from becoming unstable after the engine is started.
[0039]
The embodiments of the present invention are not limited to those described above, and can be variously modified without departing from the spirit of the present invention. For example, in the present embodiment, the case where the engine 1 is applied to an idle stop vehicle has been described. However, the present invention can also be applied to a hybrid vehicle that automatically stops the engine when the engine does not need to be driven and runs with the driving force of an electric motor. . In this case, the present invention can be applied to both a series hybrid vehicle in which the engine is exclusively used for power generation and a parallel hybrid vehicle in which the driving force of the engine and the driving force of the motor are appropriately combined and transmitted to the wheels. It is particularly suitable to use the present invention in a parallel hybrid vehicle whose performance is directly reflected in the driving feeling.
[0040]
Further, in the present embodiment, when the fuel pressure becomes equal to or lower than the predetermined pressure during the automatic stop of the engine 1, the fuel is injected into the cylinder located in the compression stroke and the cylinder to be the next compression stroke while the engine 1 is stopped. Although configured, the fuel may be injected into at least one of the cylinder located in the compression stroke and the next cylinder in the compression stroke.
[0041]
【The invention's effect】
As described above in detail, according to the automatic stop and start apparatus for a direct injection internal combustion engine of the present invention, when the fuel pressure drops below a predetermined pressure during automatic stop, the compression is performed while the internal combustion engine is stopped. Since fuel is injected into the cylinder located in the stroke and / or the cylinder that will be the next compression stroke, even if the restart condition is satisfied after the fuel pressure drops and fuel can be substantially injected only in the intake stroke, the fuel is injected into the compression stroke. By supplying fuel in advance to the cylinders located and / or the cylinders that will be in the next compression stroke, the compression stroke injection can be performed substantially in the first or second cylinder that is ignited first, and rapid start-up becomes possible. For this reason, the automatic stop period in which quick start is possible can be lengthened, and fuel consumption can be further reduced while quick start is enabled.
[0042]
Further, according to the automatic stop and start apparatus for a direct injection internal combustion engine of the present invention described in claim 2, since the injection amount of fuel injection performed while the internal combustion engine is stopped is determined according to the stop crank angle, An appropriate amount of fuel can be injected according to the piston stop position of the cylinder into which fuel is injected.
According to the third aspect of the present invention, the start control means prohibits the fuel injection in the compression stroke for a predetermined period after the start and performs the fuel injection in the intake stroke. Since it is configured to continue, it is prohibited to perform the compression stroke injection in a state where the fuel pressure is low, and it is possible to prevent the operation of the engine from becoming unstable after the start of the internal combustion engine.
[0043]
Further, according to the automatic stop and start device for a direct injection internal combustion engine of the present invention, the start control means performs the cylinder located in the compression stroke and the next compression stroke while the engine is stopped. Since fuel is injected into the cylinders, even when the fuel pressure is low, the two cylinders that are first ignited at the time of restart can substantially execute the compression stroke injection, and the engine can be reliably and quickly automated.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration of a main part of an automatic stop / start device for a direct injection internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a map for setting a fuel injection amount in an automatic stop / start device for a direct injection internal combustion engine according to an embodiment of the present invention.
FIG. 3 is a time chart for explaining an operation of the automatic stop / start device for the direct injection internal combustion engine according to the embodiment of the present invention;
FIG. 4 is a time chart for explaining the operation of the automatic stop / start device for the direct injection internal combustion engine according to the embodiment of the present invention;
FIG. 5 is a flowchart illustrating an operation of the automatic stop / start device for the direct injection internal combustion engine according to the embodiment of the present invention;
FIG. 6 is a flowchart illustrating an operation of the automatic stop / start device for the direct injection internal combustion engine according to the embodiment of the present invention;
FIG. 7 is a diagram showing a general relationship between a fuel pressure and an indicated average effective pressure (torque) at the time of engine start by compression stroke injection.
[Explanation of symbols]
1 engine (internal combustion engine)
14. Fuel pressure sensor (fuel pressure detecting means)
20 ECU (control means)
21 Cylinder discriminating means
22 Start control means

Claims (4)

An automatic stop and start device for a direct injection internal combustion engine that automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied and starts the internal combustion engine when a predetermined restart condition is satisfied.
Fuel pressure detecting means for detecting the pressure of the fuel supplied to the fuel injection valve of the internal combustion engine,
Cylinder determining means for detecting the cylinder position of the internal combustion engine during automatic stop,
When the fuel pressure detected by the fuel pressure detecting means becomes equal to or lower than a predetermined pressure during the automatic stop of the internal combustion engine, fuel is supplied to the cylinder located in the compression stroke and / or the cylinder to be the next compression stroke while the internal combustion engine is stopped. A start control means for injecting fuel and then injecting fuel into a cylinder located in an intake stroke when the above-mentioned restart condition is satisfied. 2. The automatic stop and start apparatus for a direct injection internal combustion engine according to claim 1, wherein an injection amount of fuel injection performed while the internal combustion engine is stopped is determined according to a stop crank angle. 2. The automatic stop and start system for a direct injection internal combustion engine according to claim 1, wherein said start control means inhibits fuel injection in a compression stroke and continues fuel injection in an intake stroke for a predetermined period after starting. . 2. The cylinder injection type internal combustion engine according to claim 1, wherein the start control means injects fuel into a cylinder located in a compression stroke and a cylinder which is next in a compression stroke while the engine is stopped. 3. Automatic stop and start device.

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