JPH11101173A - Startup control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve startability of an engine by setting a scavenging mode at the time of detecting the state of failing to start the engine even after the lapse of cranking operating time of specified time or more and the state of repeating startup failures specified times or more due to cranking operating time being too short. SOLUTION: When a starter switch 10 is switched on, elapsed time T from startup operation is clocked in a control unit 11. After the starter switch 10 is switched off, cranking operating time T is integrated to compute integrated time ΣT. Whether or not engine rotating speed N is in complete combustion is judged in comparison to judgment reference rotating speed NO. At the time of N<=NO, whether or not cranking time T this time is the specified time T1 or more is judged. In the case of failing to start even though cranking operation is performed for specified time T1 or more, a startup failure is judged, and a scavenging mode is set to accelerate fuel gasification in an engine for early discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for improving the startability of an internal combustion engine.

[0002]

2. Description of the Related Art When starting an internal combustion engine by cranking, if the fuel supplied to an intake port or a cylinder accumulates or the spark plug becomes wet with fuel, the starting becomes impossible or difficult. Therefore, if the engine speed does not increase and the engine does not start with the throttle valve opening being larger than the predetermined value during cranking, it is determined that excess fuel has been supplied to the engine and accumulated, and There is an apparatus in which a mode is set in which the supply of fuel is stopped and the engine is rotated to scavenge the fuel stored in the engine (see JP-A-5-321714).

[0003]

However, in setting the scavenging mode based only on the engine operating state (throttle valve opening) at the time of cranking as described above,
Since it was not possible to accurately detect the condition that required scavenging, scavenging was not performed in a mode that required scavenging, or conversely, scavenging mode was set even when scavenging was not required, making subsequent starting difficult. There was a thing.

The present invention has been made in view of such conventional problems, and provides an internal combustion engine start control device capable of accurately grasping a state where scavenging is required and performing scavenging. Aim.

[0005]

Therefore, according to the present invention, the engine is not started even if the cranking operation time exceeds a predetermined time, and the cranking operation time is too short. A state in which the starting failure due to the engine is repeated a predetermined number of times or more is detected, and when a state in which starting is difficult is detected, a scavenging mode for scavenging while evaporating fuel stored in the engine is set. And

According to the first aspect of the present invention, when the engine does not start even after the cranking operation time that is longer than a predetermined time that should have been successful in starting the engine, fuel is supplied to the intake port or the cylinder before the cranking. Or accumulate in
It is considered that the starting is impossible because deposits are deposited on the exhaust valve and only the air escapes and fuel is accumulated in the cylinder. Also, if the cranking operation time is too short than the minimum time required for starting and the engine fails to start over and over again, fuel will accumulate in the engine or the spark plug will get wet, and the normal Even if a ranking operation is performed, a situation where starting is difficult is caused.

Therefore, when each of these difficult-to-start states requiring scavenging is detected, a scavenging mode is set to perform scavenging. In the invention according to claim 2, the first difficult-to-start state detecting means for detecting a state in which the engine has not been started even after the cranking operation time longer than a predetermined time has elapsed, and the cranking operation time is too short. The state where the failure of the start due to the above is repeated for a predetermined number of times or more
And a scavenging mode setting for setting a scavenging mode for scavenging while supplying the engine and evaporating accumulated fuel when the first or second difficult-to-start condition is detected. And means.

According to the second aspect of the present invention, the first difficult-to-start state detecting means and the second difficult-to-start detecting means detect the state in which starting is impossible or the state in which starting becomes difficult due to cranking operation. Then, when these states are detected, the scavenging mode setting means sets the scavenging mode and performs scavenging.

The invention according to claim 3 is characterized in that the predetermined time is variably set according to the temperature of the cooling water of the engine. According to the third aspect of the present invention, the fuel vaporization state varies depending on the cooling water temperature, and the cranking time required for starting varies. Therefore, by setting the predetermined time variably depending on the cooling water temperature, the engine cannot be started. Can be detected with higher accuracy.

According to a fourth aspect of the present invention, when the scavenging mode is set, a scavenging amount larger than the minimum necessary scavenging amount estimated according to the immediately preceding cranking operation state and the cooling water temperature of the engine can be obtained. Is set. According to the invention according to claim 4, according to the cranking operation state before the setting of the scavenging mode and the minimum required scavenging amount corresponding to the amount of fuel supplied to and accumulated in the engine during cranking according to the cooling water temperature of the engine, By setting the scavenging amount larger than this in consideration of the amount of fuel accumulated before cranking, it is possible to set a necessary and sufficient scavenging amount.

The invention according to claim 5 is an engine wherein the opening of the throttle valve is electronically controlled, wherein the scavenging mode is set including increasing the opening of the throttle valve of the engine. It is characterized by. According to the fifth aspect of the invention, the opening degree of the throttle valve is increased to reduce the flow resistance of the intake air, the intake air amount is increased, and the compression temperature is increased to promote the vaporization of the fuel. Scavenging the fuel that accumulates in the tank efficiently.

Further, the invention according to claim 6 is characterized in that the scavenging mode is set including bringing the closing timing of the intake valve closer to the intake bottom dead center. According to the invention of claim 6, by bringing the closing timing of the intake valve close to the intake bottom dead center, the compression ratio is increased, the intake air amount is increased, and the compression temperature is raised to promote the vaporization of fuel. This effectively scavenges the fuel accumulated in the engine.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a system configuration according to an embodiment of the present invention. The accelerator opening sensor 1 detects the amount of depression of the accelerator pedal depressed by the driver as information on the load (engine torque) of the engine desired by the driver.

The crank angle sensor 2 generates a position signal for each unit crank angle and a reference signal for each cylinder stroke phase difference, and measures the number of the position signals generated per unit time, or generates the reference signal. By measuring the period, the engine speed can be detected. The air flow meter 3 detects the amount of air taken into the engine 4.

The water temperature sensor 5 detects the temperature of the cooling water of the engine. An intake passage 6 of the engine 4 is provided with a fuel injection valve 7 driven by a fuel injection signal to supply fuel and a throttle valve 8 for controlling the amount of intake air, and the opening of the throttle valve 8 is electronically controlled. Possible throttle valve controller 9
Is provided. A detection signal from the various sensors and a signal from the starter switch 10 are input to a control unit 11, and the control unit 11 controls the throttle valve according to an operation state detected based on a signal from the sensors. The opening degree of the throttle valve 8 is controlled via a control device 9, the fuel injection valve 7 is driven to control the fuel injection amount, and the starter switch
The scavenging mode is set when necessary based on the cranking operation state based on the signal from 10.

A control routine at the time of cranking according to the first embodiment of the present invention will be described below with reference to the flowchart of FIG. This routine uses the starter switch
Executed when 10 is turned on. In step (denoted as S in the figure, the same applies hereinafter), in step 1, it is determined whether or not the scavenging mode is set based on the value of the flag F.

If it is determined in step 1 that the scavenging mode has not been set, the process proceeds to step 2, where the elapsed time since the starter switch 10 was turned on, that is, the cranking operation time T is measured by a timer. In step 3, the process waits for the starter switch 10 to be turned off, and proceeds to step 4. In step 4, the cranking operation time T
To calculate the cranking integration time ΔT from when the starter switch 10 is first turned ON.

In step 5, it is determined whether or not the engine speed N has completely exploded, that is, whether or not the engine has been successfully started by comparing it with a reference rotation speed N0. If it is determined that N> N0 and the start is successful, the routine proceeds to step 6, where the cranking integration time ΔT is reset to zero. Step 5
If it is determined that the engine is not started with N ≦ N0, the routine proceeds to step 7, where it is determined whether or not the current cranking time T is equal to or longer than a predetermined time T1. This predetermined time T1
Is set as the cranking operation time that should have succeeded in starting the engine. If the cranking operation is not successful even if the cranking operation is performed for the predetermined time T1 or more, the fuel is supplied to the intake port or the cylinder before the cranking. Or accumulate in
It is considered that the starting is impossible because deposits are deposited on the intake / exhaust valves and only the air escapes and fuel is accumulated in the cylinder. Further, the cranking operation time required for successful start-up changes as the vaporization state of the fuel changes depending on the coolant temperature, and therefore, the predetermined time T1 depends on the coolant temperature detected by the coolant temperature sensor 5. Change and set. Specifically, the lower the cooling water temperature, the worse the fuel vaporization state and the more difficult it is to start the engine. Therefore, the predetermined time T1 is set to be longer.

If it is determined in step 7 that T ≧ T1, it is determined that the engine cannot be started for the above-described reason, and the routine proceeds to step 10, where the flag is set to 1 to set the scavenging mode.
Set to. When it is determined in step 7 that T <T1, it is determined that the starting operation cannot be determined to have failed because the cranking operation time is too short, and step 8 is performed.
Then, the number N of times that the starting has failed since the cranking was performed first is integrated.

In step 9, it is determined whether or not the cumulative number N of the start failures exceeds a predetermined number Nf. If it is determined in step 9 that N> Nf, the so-called choking with a short cranking operation time is repeated and the start failure is repeated many times, so that a large amount of fuel is accumulated in the intake port or the cylinder, Alternatively, it is determined that starting has become difficult due to wetting of the spark plug, and the routine proceeds to step 10, where the flag F is set to 1 in order to set the scavenging mode.

When the flag F is set to 1 when it is determined that the engine cannot be started, or when it is determined that starting has become difficult due to repeated failures of the start, the next time the start switch 10 is turned on, Since the flag F is set to 1 in the determination in step 1, the process proceeds to step 11 and the scavenging mode is set. Specifically, the opening of the throttle valve 9 is increased to a predetermined opening, fuel injection is stopped or the fuel injection amount is reduced, and cranking is performed by a starter motor. As a result, the intake air amount increases and the compression temperature rises, so that the fuel stored in the intake port and the cylinder and the fuel that wets the spark plug can be efficiently scavenged while promoting the vaporization of the fuel.

Here, the amount of fuel stored in the engine during cranking is estimated in accordance with the cranking operation state and the coolant temperature, and the amount of fuel stored in the engine before cranking is estimated. If the scavenging amount is controlled in accordance with the estimated amount of fuel accumulated in the engine, necessary and sufficient scavenging can be performed. More specifically, when it is determined that the engine cannot be started because the cranking time is too long, the cooling water temperature is determined based on the cranking time T and the coolant temperature. Based on at least the amount of fuel stored in the engine by the present cranking, and the amount of fuel that may have been stored in the engine before cranking is added to this to estimate the amount of fuel pooled. When the estimated fuel accumulation amount is large, the opening degree of the throttle valve 9 may be increased or the control may be performed so as to prolong the scavenging time.

In step 12, the flag F, the integrated cranking time ΔT, and the number N of times of starting failure are reset to 0 in preparation for the next cranking operation after the setting of the scavenging mode. Further, in the present embodiment, the air amount is increased by increasing the throttle valve opening when the scavenging mode is set, but in an engine capable of variably controlling the opening of the intake valve,
When the scavenging mode is set, the closing timing of the intake valve may be delayed to approach the intake bottom dead center side.

FIG. 4 shows the configuration of a valve drive device 20 for an internal combustion engine that electronically controls the opening and closing of intake and exhaust valves to which the present embodiment is applied. In FIG. 4, the intake valve has an elongated valve rod 21,
A power piston 22 slidably inserted in a sleeve 23 is connected to the valve rod 21, and a control valve 24 is provided outside the sleeve 23.
Are slidably inserted. Variable volume chambers 25 and 26 are defined on both sides of the power piston 22. When the control valve 24 is in the position shown in FIG. The high-pressure liquid flows into the left chamber 25 in the drawing, while the liquid in the right chamber 26 is discharged to the low-pressure side via the port 29 of the control valve 24. Thus, the valve rod 21 moves rightward to the position shown in the figure while compressing the air in the air chamber 31 by the braking piston 30 connected to the valve rod 21, and opens the intake valve.

When the holding effect of the magnet 27 is canceled by the bias of the coil 32 on the left side in the figure, the control valve 24 moves rightward in the figure by the attraction force of the spring 33 and the magnet 34 on the right side. Thereby, the high-pressure liquid in the chamber 25 flows out to the low-pressure side via the port 32 of the control valve 24, and the control valve 24
Since the communication with the port 28 is maintained, the valve rod 21 remains open to the low pressure side, and in this state, the valve rod 21 moves leftward in the figure integrally with the braking piston 30 by the compressed air pressure in the air chamber 30. Then, the intake valve 3 is seated on the valve seat 35 and closed.

As described above, the intake valve can be opened and closed at any time by turning on and off the energization of the coil 30. Therefore, in the present embodiment, when the scavenging mode is set, control is performed such that the closing timing of the intake valve is advanced from that in the normal operation to approach the intake bottom dead center. As a result, the compression ratio is increased, the intake air amount is increased, the compression temperature is raised, and the vaporization of the fuel is promoted, and the fuel stored in the engine is scavenged efficiently.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 shows a system configuration according to the first embodiment.

FIG. 3 is a flowchart illustrating a control routine during cranking according to the first embodiment.

FIG. 4 is a cross-sectional view illustrating a configuration of a valve driving device for an internal combustion engine to which the second embodiment is applied.

[Explanation of symbols]

 4 Engine 5 Water temperature sensor 6 Intake passage 7 Fuel injection valve 8 Throttle valve 9 Throttle valve controller 11 Control unit 20 Valve drive

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI F02N 17/00 F02N 17/00 B 17/08 17/08 Z

Claims (6)

[Claims] The present invention detects a state in which the engine has not been started even if a cranking operation time longer than a predetermined time has elapsed, and a state in which starting failure due to too short a cranking operation time has been repeated a predetermined number of times or more. A start-up control device for an internal combustion engine, which sets a scavenging mode for scavenging while accumulating fuel stored in the engine when a state in which starting is difficult is detected. 2. A first difficult-to-start state detecting means for detecting a state in which the engine has not been started even when a cranking operation time longer than a predetermined time has elapsed, and starting failure due to too short a cranking operation time. Second start difficult state detecting means for detecting a state in which is repeated a predetermined number of times or more, and when the first or second difficult start state is detected, the fuel supplied to the engine and stored there. A scavenging mode setting means for setting a scavenging mode in which scavenging is performed while vaporizing, and a start control device for an internal combustion engine, comprising: 3. The start control apparatus for an internal combustion engine according to claim 1, wherein the predetermined time is variably set according to a temperature of a cooling water of the engine. 4. A scavenging mode is set such that a scavenging amount larger than a minimum necessary scavenging amount estimated according to the immediately preceding cranking operation state and the cooling water temperature of the engine is obtained. A start control device for an internal combustion engine according to any one of claims 1 to 3. 5. An engine in which the opening of a throttle valve is electronically controlled, wherein the scavenging mode is set including increasing the opening of the throttle valve of the engine. A start control device for an internal combustion engine according to claim 4. 6. The scavenging mode according to claim 1, wherein the scavenging mode is set including bringing the closing timing of the intake valve close to the intake bottom dead center. Start control device for internal combustion engine.