JP2001221138A - Starting system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starting system for an internal combustion engine capable of surely stopping the engine at a specified crank angle with a simple control and improving starting characteristics in subsequent starting. SOLUTION: A stopping position of a crank shaft is detected by a crank shaft sensor at the time of stopping of the internal combustion engine (step S4), and the crank shaft is rotated by a starter so as to be positioned at an optimum crank position being optimum for restarting the internal combustion engine (step S10). The optimum crank position is surely realized by the above- mentioned simple control for the starter, and cranking is started from the optimum crank position in subsequent starting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine (hereinafter referred to as "internal combustion engine").
(Referred to as an engine).

[0002]

[Related Background Art] Various types of engine starters of this type have been proposed to improve the startability.
As an example thereof, one described in JP-A-11-107793 can be mentioned. In this starting device, a crank angle with good startability is determined in advance, and when the engine is stopped, which cylinder should be burned last in order to stop at the target crank angle is selected according to the operating state. By continuing the control until the selected cylinder is burned, the engine is stopped at the target crank angle, and the subsequent startability is improved.

[0003]

In the engine starting device described in the above-mentioned publication, the engine is stopped at a target crank angle by selecting a cylinder that burns last. However, this method is not reliable because the various factors such as the friction of the engine itself and the driving resistance of the auxiliary equipment affect the startability because the engine cannot be stopped at the target crank angle. was there. In addition, it is necessary to perform a cylinder selection process every time the engine is stopped. In addition, it is very difficult to terminate the combustion in the selected cylinder even if the contents of fuel injection and ignition timing are changed. Even more, it was impossible to stop at the target crank angle.

An object of the present invention is to provide a starting device for an internal combustion engine capable of reliably stopping the engine at a predetermined crank angle by a simple control and improving the startability at the time of subsequent starting. .

[0005]

According to the present invention, there is provided an internal combustion engine comprising: a crankshaft sensor for detecting a rotational position of a crankshaft of an internal combustion engine; and an electric motor capable of cranking the internal combustion engine. The stop crankshaft position is detected by a crankshaft sensor at the time of stoppage, and the crankshaft is rotated by an electric motor so as to have an optimum crank position that is optimum for restarting the internal combustion engine. Therefore, the internal combustion engine after being stopped is rotated to the optimum crank position by the electric motor, and cranking is started from the optimum crank position at the time of starting thereafter, and the time required for complete explosion is reduced. Thus, the optimum crank position can always be reliably realized by the simple control for the electric motor.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a starting device for a direct injection type engine used in an idle stop vehicle will be described below. In the overall configuration diagram of FIG.
Reference numeral 1 denotes a cylinder injection gasoline engine, which is 180 ° CA
It is configured as a 4-cycle in-line 4-cylinder that explodes at equal intervals every time. The combustion chamber and the intake system of the engine 1 are designed exclusively for in-cylinder injection, and each cylinder is provided with a spark plug 2 and a fuel injection valve 3 so that fuel can be directly injected into the cylinder. I have.

A manual transmission 4 is connected to the engine 1, and this transmission is connected to driving wheels of the vehicle via a differential gear (not shown). A clutch 5 is provided between the engine 1 and the transmission 4. The clutch 5 controls power transmission from the engine 1 to the transmission 4 according to a clutch operation by a driver. The engine 1 is provided with a constant mesh starter 6 as an electric motor, and a pinion gear 6 a of the starter 6 is always meshed with the flywheel 1 a of the engine 1. The flywheel 1a is provided with a one-way clutch (not shown). The one-way clutch performs cranking by transmitting the driving force of the starter 6 to the engine 1 at the time of starting.
In addition, the starter 6 is prevented from being reversely driven by the engine 1 by idling after the start is completed.

The starter 6 is connected to the battery 11 via an ignition switch (not shown) and to the battery 11 via a relay contact 12a of the starter control controller 12. Accordingly, the starter 6 is energized in accordance with the operation of the ignition switch as in the normal case, and is also energized when the relay contact 12a is closed by the excitation of the relay coil 12b of the starter control controller 12.

An input / output device (not shown), storage devices (ROM, RAM, BURAM, etc.) for storing control programs and control maps, and a central processing unit (C)
PU), an ECU 21 (engine control unit) including a timer counter and the like. On the input side of the ECU 21, an engine temperature sensor 22 for detecting the temperature T of the engine 1, a crank angle sensor 23 for outputting a crank angle signal with the rotation of the crankshaft of the engine 1, and a TOP signal with the rotation of the camshaft. , A vehicle speed sensor 25 for detecting the vehicle speed V, a clutch sensor 26 for detecting the operation state of the clutch 5, an accelerator sensor 27 for detecting the accelerator operation amount Acc, and the transmission 4
Are connected to a shift position sensor 28 for detecting the shift position, and various other switches and sensors.

The output side of the ECU 21 is connected to the ignition plug 2 and the fuel injection valve 3 as well as the relay coil 12b of the starter control controller 12. The ECU 21 executes various controls for operating the engine 1, including fuel injection control and ignition timing control, based on the above-described respective detection information, and executes an automatic stop / start process of the engine 1 when the vehicle is stopped such as at a traffic light. .
Further, the ECU 21 changes the crank angle of the engine 1 to an optimum position by the starter 6 as necessary while the engine is stopped, thereby ensuring the startability thereafter.

In the in-cylinder injection type engine 1 configured as described above, in addition to uniform combustion in which fuel is injected in a normal intake stroke to form a uniform mixture in the cylinder, fuel is injected in a compression stroke. Thus, stratified combustion in which combustion is performed at an ultra-lean overall air-fuel ratio is enabled. The stratified combustion is generally performed in a low-rotation, low-load operation region, and the ECU 21 determines the target average effective pressure Pe (representing the engine load) obtained from the accelerator operation amount Acc or the like detected by the accelerator sensor 27, and the crank angle sensor 23. The compression stroke injection is performed in a region where the engine rotation speed Ne obtained from the crank angle signal is relatively low, thereby achieving a reduction in emissions and an improvement in fuel consumption, and the intake stroke injection is performed in a region beyond that. Secure engine torque.

Next, an automatic stop / start process of the engine 1 specific to an idle stop vehicle will be described. The ECU 21 automatically stops the engine 1 when a preset engine stop condition is satisfied, and automatically starts the engine 2 when a preset engine start condition is satisfied, when the running vehicle stops at a signal or the like. This prevents emissions and fuel consumption during a stop. The engine stop condition includes the vehicle speed V detected by the vehicle speed sensor 25.
Is zero, the clutch 5
Is set (the clutch engagement state) and the shift position detected by the shift position sensor 28 is set to the N (neutral) position.
When these conditions are satisfied, the ECU 21 determines that the engine stop condition is satisfied, stops the fuel injection control and the ignition timing control, and stops the engine 1.

The engine start conditions are that the clutch sensor 26 detects that the clutch 5 has been depressed (clutch disengaged state), and that the shift position detected by the shift position sensor 28 is the N position. Is set, and when these conditions are satisfied, the ECU 21 determines that the engine start condition is satisfied, excites the relay coil 12b of the starter control controller 12, and restarts the fuel injection control and the ignition timing control. . Since the relay contact 12a is closed by excitation of the relay coil 12b, the starter 6 is energized to perform cranking,
The engine 1 can be started by starting.

Then, automatic start based on the establishment of the engine start condition, and normal ignition switch ON
In any of the manual starting by the operation, in the present embodiment, the early starting control is executed to achieve the quick starting. The early start control means that the fuel is injected and ignited to a cylinder in a compression stroke (hereinafter, referred to as a compression stroke cylinder) or a cylinder in an intake stroke (hereinafter, referred to as an intake stroke cylinder) while the engine is stopped. It is control to make it explode. Here, for example, when the piston position of the compression stroke cylinder when the engine is stopped can hardly be compressed near the top dead center, the initial explosion cannot be obtained in the compression stroke cylinder and it will be delayed to the subsequent intake stroke cylinder. In the present embodiment, the crank angle change control is executed when the engine is stopped, so that the first explosion in the compression stroke cylinder is always possible.

The details of the crank angle changing control will be described below. In either case of the automatic stop based on the satisfaction of the engine stop condition or the manual stop by the normal operation of turning off the ignition switch, the power supply to the ECU 21 is continued, and the ECU 21 executes the crank angle change routine shown in FIG. At the control interval of First, the ECU 21 determines in step S2 that the crank angle sensor 23
The stop of the rotation of the crank is confirmed based on the crank angle signal from the CPU, and the crank angle is calculated based on the crank angle signal immediately before the engine is stopped and the TOP signal detected by the cam angle sensor 24 in step S4. In the following step S6, it is determined whether or not the engine is to be started. When the above-described automatic start or manual start is performed, a determination of YES (affirmation) is made in step S6, and the routine is terminated as it is. Therefore, in this case, the engine 1 is started immediately without changing the crank angle.

If the determination in step S6 is NO (No), the process proceeds to step S8 to determine whether or not the current crank angle matches a preset optimal crank angle. This optimum crank angle is the crank angle most convenient for the initial stroke control of the compression stroke cylinder, and more specifically, the compression stroke cylinder can be reliably detonated for the first time, and the shortest stroke until the first detonation is achieved. This is the crank angle when the piston of the compression stroke cylinder is located as close to the top dead center (retard side) as possible. As will be described later, the optimum crank angle differs according to the operating state of the engine 1 immediately before the stop and the current state of the engine 1, and therefore, in step S8, the optimum crank angle is determined from a preset map, and the optimum crank angle is determined. Compare the crank angle with the current crank angle. If the determination in step S8 is YES, it is determined that the crank angle does not need to be changed, and the routine ends.

On the other hand, if the determination in step S8 is NO, since a good initial explosion cannot be expected in the compression stroke cylinder, the relay coil 12b of the starter control controller 12 is excited in step S10 to change the crank angle. Thereafter, the crank angle is calculated in step S4 as described above, and after step S6, it is determined in step S8 whether or not the crank angle matches the optimum crank angle, and the processing in steps S4 to S10 is repeated. Since the relay contact 12a is closed by exciting the relay coil 12b in step S10, the crank angle is gradually changed by cranking by the starter 6, and when the value matches the optimum crank angle, the determination in step S8 is YE.
The routine is ended because S is reached. Therefore, the process of step S10 is stopped, and the crank angle is maintained at the optimum crank angle.

The starter 6 for changing the crank angle is:
Since the engine 1 is driven in the combustion cycle direction in the same manner as at the start, if the piston position of the compression stroke cylinder has already passed the piston position at the optimum crank angle, the two cannot be matched. Accordingly, in this case, the subsequent intake stroke cylinder is regarded as the compression stroke cylinder, and the drive of the starter 6 is continued until the piston position of the new compression stroke cylinder reaches the piston position at the optimum crank angle.

When the above-described automatic start or manual start is performed during the change of the crank angle, the determination in step S6 becomes NO, so that the crank angle change process is interrupted and the engine 1 is started immediately. You. Even in such a case, since the crank angle is changed halfway toward the optimum crank angle, the probability of the first explosion succeeding in the compression stroke cylinder increases.

As described above, the optimum crank angle applied in step S8 is set according to the operating state of the engine 1 immediately before stopping or the current state of the engine 1. For example, when the engine 1 is in the lean operation and the stoichiometric operation immediately before the stop, the amount of intake air taken into the compression stroke cylinder after the stop is different, so that the piston position where the first explosion is naturally caused also differs. In addition, for example, when the piston position is set based on the current engine temperature T detected by the engine temperature sensor 22, when the engine temperature T is high, the heat receiving area is reduced in order to suppress the temperature rise of the air in the cylinder, That is, the crank angle is set to be advanced, and when the engine temperature T is low, the air in the cylinder is easily heated and the time for fuel vaporization is increased, so that the heat receiving area is increased, that is, the crank angle is delayed. Set. Therefore, since the ignitability differs depending on the in-cylinder gas temperature of the compression stroke cylinder, etc., the piston position that facilitates the first explosion naturally differs,
In step S8, an optimal crank angle is set based on a map set in consideration of these factors.

The actual crank angle when the engine is stopped is dispersed within a certain range with respect to the optimum crank angle, and the dispersed state differs depending on the operating state of the engine 1 immediately before the stop. FIGS. 3 and 4 show the piston position of the compression stroke cylinder when the engine 1 is stopped in the lean operation and the stoichiometric operation. In the lean operation with a large intake amount as shown in FIG. Since the piston is pushed back by receiving a strong compression reaction force at the point, the distribution of the piston positions is concentrated in the range of BTDC 65 to 110 ° CA, and the compression reaction force is not so strong in the stoichiometric operation with a small intake amount as shown in FIG. This indicates that the distribution of piston positions is more widely dispersed.

In this embodiment, the crank angle is forcibly changed to the optimum crank angle even when the engine 1 is stopped at any of the piston positions shown in FIGS. Therefore, Japanese Unexamined Patent Application Publication No.
Unlike the starting device described in the publication, the cranking can always be reliably started from the optimum crank angle, and the crank angle is changed as compared with the starting device described in the publication requiring complicated control. Can be realized simply by executing the routine.

By the change of the crank angle, the compression stroke cylinder can be explosively and quickly exploded for the first time by the shortest cranking at the time of subsequent starting, and the time required for complete explosion can be greatly reduced. Therefore, especially when the engine 1 is automatically started at a traffic light or the like, it is possible to immediately start the engine 1 and quickly start the vehicle without giving a sense of incongruity to the driver, thereby improving the commercial value of the idle stop vehicle. Can be done.

Further, since the start is completed by the shortest cranking, the power consumption of the starter 6 at the time of the start can be reduced.
In addition, since the engine can be reliably started without misfiring, it is possible to achieve a reduction in emission at the time of starting and to suppress an increase in fuel at the time of starting, thereby achieving a reduction in fuel consumption. On the other hand, the quick start of the vehicle described above is more remarkably obtained, for example, when the manual transmission 4 of the present embodiment is replaced with an automatic transmission or a CVT (continuously variable transmission). That is, in these automatic transmissions and CVTs, clutch engagement and the like are performed by a hydraulic pump driven by the engine. Therefore, if the engine is started early, the time required for starting preparation by clutch engagement is reduced. It can be started more quickly as a result.

Although the embodiment has been described above, aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the starting device of the in-cylinder direct injection engine 1 of the in-line four cylinder used for the idle stop vehicle is embodied. It may be embodied as a starting device for an in-line three-cylinder engine or a V-type six-cylinder engine.

Further, in the above-described embodiment, the engine 1 that executes the early start control for the compression stroke cylinder and the intake stroke cylinder is provided.
The crank angle is changed to the optimum crank angle for the first explosion of the compression stroke cylinder, but the in-cylinder injection type engine that does not execute the early start control or the fuel is injected into the intake pipe. It may be embodied as a starting device for a general intake pipe injection type engine. For example, in an intake-pipe injection engine, if the optimum crank angle is set immediately before the intake valve of a certain cylinder is opened, the injected fuel is sucked into the cylinder at the same time as cranking starts and is immediately compressed and burned. , Can be started quickly.

Further, in the above-described embodiment, the crank angle of the engine 1 is changed by the constant mesh starter 6 using a one-way clutch. However, the mechanism for changing the crank angle is not limited to this. In a vehicle (ISG) that also serves as a generator, the starter may be used to change the crank angle of the engine,
In a hybrid vehicle (HEV), the crank angle may be changed by using a traveling motor.

On the other hand, in the above embodiment, the crank angle changed to the optimum crank angle is only maintained until the engine starts. However, as the in-cylinder gas temperature gradually rises due to the heat received from the cylinder wall and the like, the optimum crank angle also changes accordingly, so for example, the optimum crank angle is calculated every predetermined time according to the elapsed time since the engine was stopped. Then, the crank angle may be sequentially updated based on the optimum crank angle.

[0029]

As described above, according to the starting apparatus for an internal combustion engine of the present invention, the engine can be reliably stopped at the optimum crank position by simple control, and the startability at the time of subsequent starting can be improved. it can.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a starting device for a direct injection engine of an embodiment.

FIG. 2 is a flowchart illustrating a crank angle changing routine executed by an ECU.

FIG. 3 is an explanatory diagram showing a piston position of a compression stroke cylinder when the engine is stopped in a lean operation.

FIG. 4 is an explanatory diagram showing a piston position of a compression stroke cylinder when the engine is stopped in a stoichiometric operation.

[Explanation of symbols]

 Reference Signs List 1 engine (internal combustion engine) 6 starter (electric motor) 23 crank angle sensor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G093 AA01 AA04 AB00 BA00 BA21 BA22 CA02 DA05 DA07 DA13 DB05 DB10 DB12 EA00 EA05 EA13 EC02

Claims (1)

[Claims] 1. A crankshaft sensor for detecting a rotational position of a crankshaft of an internal combustion engine, and an electric motor capable of cranking the internal combustion engine, wherein a stop crankshaft position is detected by the crankshaft sensor when the internal combustion engine is stopped. Wherein the crankshaft is rotated by the electric motor so as to be at an optimum crank position that is optimum for restarting the internal combustion engine.