JP2002371887A - Starting time control device for cylinder injection internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starting time control device for a cylinder injection internal combustion engine capable of transferring running with good feeling from that with compression stroke injection to the normal running. SOLUTION: This starting time control device executes the control to perform the compression stroke injection where the fuel injection quantity is reduced in comparison with the intake stroke injection by normal control, for a predetermined period at the engine start, to transfer the running to the intake stroke injection, shortens the predetermined period when an accelerator operating quantity is more than a predetermined value, and elongates the predetermined period in non-operating condition of the accelerator. Whereby, the running by the compression stroke injection can be smoothly transferred to the normal running by the intake stroke injection without feeling shock and discomfort, whenever the generation of the quick output is asked or the output is scarcely asked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting control apparatus for a direct injection internal combustion engine which injects fuel directly into a cylinder.

[0002]

2. Description of the Related Art When a stopped engine is started, an engine of a type injecting fuel into an intake manifold (port injection type internal combustion engine) consumes a stroke until fuel is burned in a cylinder, so that the engine is rapidly operated. Starting is difficult.

In view of the above, a technique has been proposed in which an in-cylinder injection engine that injects fuel directly into a cylinder is employed, and a stopped engine is quickly started by utilizing in-cylinder injection, which is a feature of this engine. ing.

[0004] This quick start is a technique in which fuel is injected into a cylinder in a compression stroke of a stopped engine at the time of start to immediately cause an initial explosion to quickly start the engine (for example, a special technique). 2000-265879).

[0005]

However, when such control is introduced into the starting of an automobile (vehicle), lean operation by compression stroke injection immediately after starting may not be able to follow the starting torque required by the driver. Therefore, it is necessary to switch from the combustion to the normal operation based on the torque-full intake stroke injection.

[0006] If the fuel injection amount is suppressed and the fuel amount cannot be properly controlled during the period from the start to the complete explosion, the engine speed rises in the process of developing the manifold pressure, and the feeling is increased. Will be impaired.

Therefore, it is conceivable that the lean operation by the compression stroke injection is performed for a predetermined period to improve the feeling at the start while preventing the engine speed from rising immediately after the start.

However, if the predetermined period is set uniformly, for example, when the period is relatively long, even if the accelerator is largely operated during the predetermined period, normal operation is not immediately performed, and the required output does not respond. It cannot be obtained well. Also, if the predetermined period is too short, the engine may shift to the normal operation in a state where the operating state of the engine is not sufficiently stable, giving a shock feeling in a state where the accelerator is not operated (non-operating state). There was a problem that the feeling could not be improved sufficiently.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an in-cylinder injection type internal combustion engine capable of performing a good transition from the operation by the compression stroke injection to the normal operation. It is to provide a starting control device.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, a first aspect of the present invention is to provide a control system in which, when starting an internal combustion engine, a compression stroke injection in which a fuel injection amount is suppressed from a normal control for a predetermined time is executed. In this case, when the operation amount of the accelerator is equal to or more than a predetermined value, control for shortening the predetermined period is employed.

Thus, when the engine is started, the fuel supply is started by the compression stroke injection, so that the engine can be started quickly, and the control in which the fuel injection amount is suppressed from the normal control for a predetermined period is executed. It is possible to suppress the increase in the number of revolutions at the time of starting the engine and smoothly shift to the normal operation control. When the accelerator operation amount is equal to or more than a predetermined value,
Since the predetermined period, that is, the operation period of the compression stroke injection, is shortened, it is possible to promptly shift to the normal operation in a situation where rapid output generation is required, to obtain a good responsiveness and a good feeling. Secured.

According to a second aspect of the present invention, at the time of starting the internal combustion engine, a control is executed in which a compression stroke injection in which the fuel injection amount is suppressed from the normal control is executed for a predetermined time and then the control is shifted to the normal control. In the non-operation state, the control for extending the predetermined period is adopted.

[0013] Thus, when the engine is started, the fuel supply is started by the compression stroke injection, so that the engine can be started quickly, and the control in which the fuel injection amount is suppressed from the normal control for a predetermined period is executed. It is possible to suppress the increase in the number of revolutions at the time of starting the engine, and smoothly shift to the normal control. When the accelerator is in the non-operation state, the predetermined period, that is, the operation period of the compression stroke injection is extended, so that it is possible to shift to the normal control after the operation state after the start of the engine is sufficiently stabilized, and to perform the output request. When there is almost no shock, the occurrence of a shock is surely suppressed, and a good feeling is secured in a situation where a shock is easily felt.

In a preferred embodiment, the internal combustion engine is mounted on an idle stop vehicle. According to this aspect, when the internal combustion engine is started regardless of the driver's operation, which is a feature of the idle stop vehicle, it is possible to ensure output responsiveness and suppress occurrence of shock while starting the internal combustion engine without causing discomfort. Can be performed.

According to the second aspect of the present invention, when it is detected that the accelerator operation state has been reached after setting the extension of the predetermined period, the extension may be canceled. In this mode, when the accelerator operation state is reached, the control immediately shifts to the normal control,
Can respond to output requests.

Further, in the invention of claim 2, the internal combustion engine may be mounted on a vehicle with an automatic transmission capable of creep running. According to this aspect, occurrence of a sense of discomfort due to output fluctuation during creep running is suppressed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in FIGS.

FIG. 1 shows a starting control device mounted on an automobile (vehicle) having an idle stop function capable of creep running to which the present invention is applied. In the figure, reference numeral 1 denotes, for example, an in-line four-cylinder engine (internal combustion engine). It is.

The engine 1 is constructed by assembling ignition plugs 3a to 3d, intake and exhaust valves (not shown), and fuel injection valves 4a to 4d capable of directly injecting into the cylinders for each of the cylinders 2a to 2d. The in-cylinder injection is used to enable the injection in the compression stroke of each of the cylinders 2a to 2d and the injection in the intake stroke of each of the cylinders 2a to 2d. Specifically, for example, in the compression stroke injection, an injection that can form a mixture near the stoichiometric air-fuel ratio only around each of the ignition plugs 3a to 3d by utilizing a reverse tumble flow formed by the intake air is used. For the intake stroke injection, injection capable of forming a uniform air-fuel mixture in each of the cylinders 2a to 2d is used, and lean stratified combustion (combustion at an ultra lean overall air-fuel ratio) is enabled by compression stroke injection. In addition, uniform combustion is enabled by intake stroke injection.

An automatic transmission 7 is connected to the output shaft 1a of the engine 1.
Is connected. The output portion of the automatic transmission 7 is connected to driving wheels (not shown) on both left and right sides of the vehicle via a differential gear (not shown), and the rotational force output from the automatic transmission 7 is transmitted to the driving wheels. I am trying to be. Also, between the engine 1 and the automatic transmission 7,
A torque converter 6 is interposed, and the torque converter 6 enables starting and running by creep force, that is, creep starting and creep running.

A ring gear 9 provided on the output shaft 1a is engaged with, for example, a constantly meshing starter 11 via a pinion gear 10. The motor 12 of the starter 11 is connected to the battery 13 via a normally open relay contact 12a. The relay coil 12b corresponding to the relay contact 12a is connected to the ST contact 14 of the ignition switch 14.
When the ignition switch 14 is operated to the position of the ST contact 14a, the motor 11 is connected to the battery 13 via a. The ON contact 14b of the ignition switch 14 is connected via a relay contact 15a of the starter control controller 15,
The relay coil 15b is connected to the relay coil 12b, and the relay coil 15b corresponding to the relay contact 15a is connected to the battery 13. Even if the ignition switch 14 is the ON contact 14b, the motor 11 is energized by using the relay contact 15a. is there.

The selector lever 7a of the automatic transmission 7 is configured to select various ranges such as D, N, R, and P by operating the lever. Then, each selected range position is indicated by a sensor, for example, an invita switch 7.
b.

On the other hand, reference numeral 20 denotes an EN for controlling the engine 1.
G-ECU (hereinafter, referred to as ECU 20) and 21 are AT-ECUs (hereinafter, referred to as ECU 21) for controlling the automatic transmission 7. Each of the ECUs 20 and 21 is composed of, for example, a microcomputer. And ECU
20 and 21 are connected to each other so that cooperation can be obtained.

The ignition plugs 3a to 3d and the fuel injection valves 4a to 4d are connected to the ECU 20.
The ECU 20 further includes an accelerator pedal (not shown).
, For example, an accelerator opening sensor 2
2 (APS: corresponding to an accelerator operation state detecting means of claim 1), a vehicle speed sensor 23 for detecting a vehicle speed, a rotation speed sensor 24 for detecting a rotation speed of the engine 1, and a brake oil pressure sensor for detecting a brake oil pressure for operating a brake. 25, a sensor for detecting a non-operation state of an accelerator pedal (not shown), for example, an idle switch 26 (corresponding to an accelerator operation state detecting means of claim 2), a crank angle sensor 27 for detecting a crank angle of the engine 1, and a TOP signal Is connected.

The ECU 21 is connected to the inverter switch 7b. The ECU 21 controls the automatic transmission 7 in accordance with each range position, specifically, a parking state at the P range position, switching of the reverse gear at the R range position, neutral switching at the N range position, and a D range. In the position, a control is set such that automatic shifting of the forward gear can be performed according to the running state of the vehicle (for example, by the accelerator opening sensor 22, the vehicle speed sensor 22, the rotation speed sensor 24, etc.). The shift required for traveling is automatically performed based on the accelerator opening and the vehicle speed.

The ECU 20 selectively uses the compression stroke injection (stratified combustion) and the intake stroke injection (uniform combustion) according to the running state of the vehicle (for example, by the accelerator opening sensor 22 and the rotation speed sensor 24). Settings to generate the required engine output.

The idle stop function is performed by the ECU 20
Is set to

The idle stop function is a combination of an "engine stop condition" for determining the stop of the engine 1 and an "engine restart condition" for determining the start of the engine 1.

The "engine stop condition" is, for example, a setting for stopping the operation of the engine 1 when the vehicle speed is zero and the brake oil pressure indicating the brake operation is equal to or higher than a predetermined value at the D range position. It is made in. Further, the "engine restart condition" is such that, for example, when the vehicle is in the D range position, a condition that a deviation per unit time of the brake oil pressure indicating a predicted action of starting the start operation is detected (the behavior of the brake pedal being loosened) is satisfied. Or, when the condition that the depression operation of the accelerator pedal is detected is satisfied, the setting is made such that a signal for starting the engine 1 is output. With this, when it becomes a driving condition that does not require the operation of the engine 1, the engine 1 is automatically stopped, and when the operation of the engine 1 is requested,
The engine 1 is automatically restarted.

The ECU 20 is set to detect a cylinder in a compression stroke immediately before the engine 1 is stopped, for example, based on a crank angle signal detected from the crank angle sensor 27 when the engine 1 is stopped. . With this setting, the cylinder of the engine 1 during the stop is identified, and more specifically, a specific cylinder located in the compression stroke is identified (corresponding to cylinder identification means).

Further, the ECU 20 is provided with a "start control function" (rapid start control) for quickly starting the stopped engine 1.

The "start-time control function" includes a control for starting the engine 1 in a compression stroke injection in which the starting fuel is suppressed as compared with the normal control, and for shifting to a normal control intake stroke injection after a predetermined period. The transition period (predetermined period) at this time is variously changed (shortened,
Control is adopted.

Specifically, the "start-time control function" includes: a. When a start signal is received from the idle stop function, the cylinder in the compression stroke is read from the cylinder identification information stored immediately before the stop, and the cranking is started, and the starting fuel whose injection amount is sequentially reduced is injected into the cylinder. (Injection in which the fuel injection amount is suppressed compared to the intake stroke injection), and the engine speed is suppressed from rising and the engine 1 is started.

B. A normal function of performing lean operation by compression stroke injection for a predetermined number of strokes, for example, nine strokes, which is a transition period (predetermined period), and then shifting to intake stroke injection which is normal control.

C. During the execution of the compression stroke injection, if the accelerator opening becomes equal to or more than a predetermined value (K1) while fuel is injected from the first compression cylinder to the Xth, for example, the third compression cylinder,
A function of reducing the number of strokes, for example, to four strokes, and increasing the fuel injection amount.

D. During the execution of the compression stroke injection, while the fuel is injected from the first compression cylinder to the Xth compression cylinder, for example, the third compression cylinder, if the idle switch 26 is on (the accelerator is not operated), the number of strokes is extended. For example, a function to extend up to 28 strokes.

E. At the time of the extension, a function of performing a compression stroke injection (torque suppression control), for example, by defining the maximum value of A / N (intake charging efficiency) so as to suppress the torque.

F. A function to immediately return to the intake stroke injection when the idle switch 26 is turned off (accelerator operation: present) within the extended stroke number.

G. During the execution of the compression stroke injection, while performing the fuel injection from the first compression cylinder to the Xth, for example, the third compression cylinder, when the accelerator opening falls below a predetermined value (K1) and the accelerator switch 26 is off, Normal number of steps (9)
Ability to maintain.

Are combined.

Then, the engine 1 is started quickly by using each function when the automobile starts, taking into account the driver's intention.

This control is shown in the flowchart of FIG.

The process from idling stop to restart of the engine 1 will be briefly described based on these flowcharts.

When stopping the vehicle, the driver depresses a brake pedal (not shown) while the selector lever 7a is set to the D range to stop the vehicle.

At this time, the ECU 20 determines that the engine 1 is operating by detecting the engine speed (NE), and then detects the signals from the vehicle speed sensor 2 and the brake oil pressure sensor 25 (step). S1).

When the vehicle speed is zero and a brake oil pressure value equal to or greater than a predetermined value is detected, the ECU 20 determines that all of the "engine stop conditions" are satisfied, and stops the operation of the engine 1 (steps S2 and S3). ).

Then, based on the outputs of the crank angle sensor 27 and the cam angle sensor 28 immediately before the engine 1 stops, the cylinder in the compression stroke during the stop is specified (step S4).

Thereafter, when the driver releases the brake in order to start the vehicle, the ECU 20 detects the loosening of the brake depressing force from the degree of deviation of the brake hydraulic pressure per unit time, and determines that there is a will to start the vehicle. From the prediction, it is determined that the “engine restart condition” is satisfied (step S5),
The process proceeds to quick start control (step S6). Even if the condition of the brake oil pressure is not satisfied in step S5, if the depression of the accelerator pedal is detected from the output of the idle switch 26, it is determined that the "engine restart condition" is satisfied.

FIG. 3 shows the details of the quick start control.

The quick start control will be described.
In response to a command from the CU 20, cranking is started, and starting fuel is injected into a cylinder in a compression stroke (a cylinder specified by a detection result immediately before stopping) with a smaller injection amount than in normal control to start the engine.

At this time, as shown in FIG. 4, a period from the time of fuel injection to the first compression stroke cylinder until a predetermined number of strokes elapses, for example, a period until fuel injection to the third compression cylinder is performed. Is determined as the determination period, the number of strokes that is the execution period (predetermined period) of the compression injection is determined based on the accelerator operation state in the determination period.

That is, as shown in FIG. 3, the ECU 20 first determines whether or not the quick start stroke number setting flag has been set. Since the flag is not set at first, the normal stroke number is first set. After setting N0, for example, "9" (steps S7 and S8), the outputs of the accelerator opening sensor 22 and the idle switch 26 are detected to determine whether or not to switch the number of strokes.

Specifically, during this determination period, the accelerator is largely operated, and the accelerator opening is equal to or greater than a predetermined value K1.
For example, suppose it is fully opened.

At this time, the ECU 20 determines that a quick start is required, such as when the vehicle is fully developed or an early accelerator operation is performed, and the number of strokes is reduced to the normal number of strokes N0 (9).
It is reset to a smaller N1 value, for example, "4", and a quick stroke number set flag is set (step S9).
-Step S11). Then, as shown in FIG. 4, the compression stroke injection is continued until the reset stroke number becomes 0 (steps S12 → S13 → S15 → S7 → S12,
Or step S12 → S13 → S15 → S16 → S7 →
S12) When the number of quick strokes becomes 0, the process is shifted to the intake stroke injection (step S19) after the end of the quick start mode (step S18). That is, quick control with a reduced transition period is performed.

By this quick control, as shown in FIG. 5, as compared with the normal time (when the number of strokes is 9), the starting acceleration with a remarkably increased acceleration is secured as compared to the normal development (when the number of strokes is 9). The vehicle can be started with high output responsiveness suitable for a situation where a high output is required.

It is assumed that the idle switch 26 is turned on (non-accelerator operation state) during the above-described determination period.

At this time, the ECU 20 determines that the vehicle starts (fully closes the accelerator) with a creep force with almost no output request, and sets the number of strokes to a value N2 larger than the normal number of strokes N0 (9), for example, It is reset to "28" (steps S22 to S24), and A / N (combustion air /
A setting for limiting the maximum value of the engine speed (engine speed) to suppress the torque (maintain a low torque) is added (step S21).
Then, in the same manner as described above, the compression stroke injection is performed as shown in FIG. 6 until the number of strokes becomes 0, and then the process shifts to the intake stroke injection (normal control). That is, quick control with an extended transition period is performed.

Here, in the running of the creep force, since there is almost no output request from the start (accelerator opening: fully closed), a shock is easily felt. However, by controlling the transition period to be extended, most of the creep running from the start is performed. Since only the compression stroke injection is performed, the engine 1 is started without discomfort, and the subsequent creep traveling can be suppressed from generating a shock, so that good creep traveling can be performed. Particularly, as shown in FIG. 6, this quick control employs a control for suppressing the generation of the torque so as to maintain the low torque by suppressing the fuel injection amount from the regulation of the A / N value. In addition to the suppression, as shown in FIG. 7, the magnitude of the shock during creep running is drastically reduced, so that good creep running can be performed.

If the idle switch 26 is turned off during the execution of the compression stroke injection for the number of strokes (28), the ECU 2
If it is 0, it is determined to shift to the starting acceleration, the number of strokes is immediately set to "0" (step S17), the quick start mode is ended (step S18), the extension is canceled, and the process shifts to the intake stroke injection (normal control). (Step S19). As a result, the output responsiveness that is immediately required is secured, and a good startability is obtained.

On the other hand, it is assumed that the accelerator switch 26 is turned off in a state where the accelerator opening falls below the predetermined value K1 during the above-described determination period.

At this time, the ECU 20 determines that the normal accelerator is operated to be small, and maintains the normal number of strokes (9) (from step S22 to step S12).
Processing toward). Then, in the same manner as described above, the compression stroke injection is performed until the number of strokes becomes zero, and then the process shifts to the intake stroke injection (normal control). That is, the transition to the intake stroke injection is performed smoothly even in the normal quick control without changing the transition period.

Therefore, the control for changing the period of transition from the compression stroke injection to the intake stroke injection prevents discomfort and shock even if the stopped vehicle is "started-started-running" in any situation. In addition to smooth transition to normal operation, appropriate output responsiveness and good feeling in each situation can be ensured.

In particular, an idling stop car (vehicle) in which the engine 1 is started regardless of a driver's operation is preferable because output responsiveness is secured while suppressing discomfort and shock. It is also suitable for an automobile (vehicle) with an automatic transmission capable of creep running, because an uncomfortable feeling such as a shock due to output fluctuation during creep running is suppressed.

The present invention is not limited to the above-described embodiment, and may be implemented with various modifications without departing from the gist of the present invention. For example, in one embodiment,
Although the compression stroke injection at the start of fuel supply is performed for the cylinder stopped in the compression stroke, the invention is not limited to this, and the injection may be started from the cylinder which is the next compression stroke. Further, in the embodiment, the intake stroke injection is described as the normal control. However, the control is not limited to this, and may be “compression stroke injection + intake stroke injection”. Further, in one embodiment, a constant-mesh type starter is used. However, the present invention is not limited to this, and a detachable starter in which a pinion projects and retracts may be used. In one embodiment, the predetermined period is set by the number of strokes, but may be set by time.

[0065]

As described above, according to the present invention, the transition from the operation by the compression stroke injection to the normal operation can be performed with a good feeling.

In particular, according to the first aspect of the present invention, when a quick output is required, the operation is shifted to the normal operation early by shortening the operation period of the compression stroke injection. Sex can be obtained.

According to the second aspect of the invention, when there is almost no output request that the accelerator is in the non-operating state, the operation period of the compression stroke injection can be extended to prevent the occurrence of a shock in a situation where a shock is easily felt. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a start-up control device for a direct injection internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an idle stop function of the start-time control device.

FIG. 3 is a flowchart illustrating a process from restarting the engine stopped by the compression stroke injection by the same function to shifting to normal intake injection.

FIG. 4 is a diagram showing an engine state when the transition period is shortened in comparison with an engine state when the operation period is not shortened.

FIG. 5 is a diagram showing acceleration performance of the vehicle at that time.

FIG. 6 is a diagram showing an engine state during creep in which the transition period is extended.

FIG. 7 is a diagram showing acceleration performance of the vehicle at that time in comparison with a case where there is no torque suppression control.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine) 2a-2d ... Cylinder 3a-3d ... Spark plug 4a-4d ... Fuel injection valve 6 ... Torque converter 7 ... Automatic transmission 11 ... Starter 20 ... ECU (cylinder discrimination means, quick control means) 22 ... accelerator opening sensor (accelerator operation state detecting means of claim 1) 26 ... idle switch (accelerator operation state detecting means of claim 2).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02D 41/10 330 F02D 41/10 330A (72) Inventor Jun Hikuma Mitsubishi Motors 33-5-8 Shiba 5-chome, Minato-ku, Tokyo Mitsubishi Motors F-term (reference) in Industrial Co., Ltd. HA01 HA04 HA16 HA17 JA02 JA04 KA01 KA28 LB04 MA11 MA19 NE22 NE23 PE03Z PE05Z PF01Z PF03Z PF05Z PF08Z

Claims (2)

[Claims] A fuel supply is started by injecting fuel in a compression stroke based on cylinder identification information by the cylinder identification means at the time of starting the internal combustion engine, wherein the fuel supply is started. A quick start control means for executing a control for suppressing the fuel injection amount from the normal control for a predetermined period of time, and then shifting to the normal control; and an accelerator operation state detecting means for detecting an accelerator operation state, the quick start control The start-up control device for a direct injection internal combustion engine, wherein the means is configured to shorten the predetermined period when the operation amount of the accelerator is equal to or more than a predetermined value. 2. A cylinder identifying means for identifying a cylinder of a stopped internal combustion engine, and a fuel supply is started by injecting fuel in a compression stroke based on cylinder identification information by the cylinder identifying means at the time of starting the internal combustion engine. A quick start control means for executing control for suppressing the fuel injection amount from the normal control for a predetermined period of time, and then shifting to the normal control; and an accelerator operation state detecting means for detecting an accelerator operation state, the quick start control The start-up control device for a direct injection internal combustion engine, wherein the means is configured to extend the predetermined period when the accelerator is not operated.