JPH0996233A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a starting time and reduce a harmful exhaust component of HC or the like, by detecting a peripheral condition in each part of an engine when it is started, arithmetically correcting a fuel amount necessary for injection, and supplying this fuel injected simultaneously to each of all cylinders of the engine before operation of a starter device. SOLUTION: When an engine 1 is started, in the case of starting control by operating an ignition key 32, in a controller 15 inputting a signal of oxygen concentration sensor 114, fuel pressure sensor 20, intake pipe pressure sensor 25, etc., before operation of a starter device 29, a fuel amount corresponding to a temperature in the periphery of the engine and a fuel pressure is calculated. Next, the obtained fuel amount is once injected simultaneously to all cylinders from a fuel injection valve 10. Thereafter, the starter device 29 is operated, also while discriminating the cylinder, fuel supply to each cylinder is started. The fuel supply is attained thus before operation of the starter device 29, so as to improve fuel injection accuracy and realize early starting of the engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for starting an engine, and more particularly to an engine control device for reducing unburned hydrocarbons (hereinafter referred to as HC) at the time of starting the engine.

[0002]

2. Description of the Related Art In recent years, exhaust emission regulations for automobiles have been set in view of ensuring the preservation of the atmosphere or environment of the entire earth. And, the regulation value becomes stricter year by year, and it is difficult for the automobile manufacturing side, that is, the manufacturer to realize the regulation, but the automobile industry is promoting various technological improvements. And actively strive to achieve this regulation.

[0003] The contents of the above-mentioned improved technology of an engine that has been generally practiced in the past are mostly based on improvement of combustion by atomization of fuel and improvement of conversion efficiency by a catalyst arranged in an exhaust system. As described above, various new technologies have been created in the fuel system and the exhaust system, but it can be said that there is still sufficient room for development and improvement regarding the problem of HC exhaust, which is one of the exhaust problems. That is, regarding HC that is discharged in large quantities at the time of engine start, analysis of fuel supply, combustion phenomenon, etc., which is the root of HC discharge, at the time of engine start has just begun, and there is no accumulated technology.
Since the mechanism of the phenomenon of HC emission has not been sufficiently analyzed and no substantial improvement has been achieved, the present situation is that effective and exhaustive reduction of HC at the time of starting has not been achieved. .

As a conventional example of the engine control device, which is focused on when the engine is started, for example, Japanese Patent Laid-Open No. 1-17 is available.
There is a technique described in Japanese Patent No. 0735. The technique is to inject fuel according to the stroke of each cylinder of the engine, so-called,
A fuel injection control device at the time of starting a multi-cylinder engine of a sequential injection system, in which only the first signal of the engine start is simultaneously injected to all cylinders in synchronization with a detection signal of the timing of engine rotation start. The purpose of this invention is to shorten the starting time by eliminating the wasteful ignition of ignition due to the delay in the fuel supply at the time of starting. Further, as another conventional example, there is JP-A-58-160523.
There is a technique described in Japanese Patent Publication No. The technique is a fuel injection control device for injecting fuel in accordance with the stroke of each cylinder of the engine, that is, a so-called sequential injection type multi-cylinder engine at the time of starting, and immediately after the ignition switch of the engine starts to operate. Performing the first fuel injection to the cylinders at the same time, and, immediately after starting, until each cylinder has passed one intake stroke, without any combustion injection valve, immediately after each one intake stroke, The second and subsequent fuel injections are performed in a predetermined order, and this makes it possible to prevent the fuel from being injected twice or not even once when the fuel is injected into each cylinder immediately after the start. .

[0005]

When the engine is started, the engine operates the ignition key to drive the starter device. The starter device is driven by the battery arranged in the engine. A fuel pump that supplies fuel to a fuel injection valve that injects fuel is also driven by the electric power from the battery. Therefore, when the starter device is driven for starting rotation of the engine, the voltage of the battery tends to decrease, and due to the decrease, the driving force of the fuel pump decreases, and as a result, the voltage is supplied to the fuel injection valve. However, there is a problem in that the fuel injection pressure decreases and the fuel injection amount decreases even if the fuel injection valve is opened for the same period of time as when there is no voltage decrease.

Further, in the above-mentioned conventional example, at the time of starting the engine, fuel is simultaneously injected into all the cylinders of the engine. However, it is not intended to consider HC at the time of starting the engine, and No consideration has been given to the relationship between the drive of the starter at the start and the amount of injected fuel. Therefore, even in the technique of the conventional example, the problem of HC at the time of starting the engine has not yet been sufficiently solved, and even if complete combustion of fuel is achieved in each cylinder at the time of starting the engine. Absent.

The present invention has been made in view of the above problems, and an object of the present invention is to shorten the starting time and the harmful exhaust components such as HC, that is, at the time of starting the internal combustion engine. In order to improve the exhaust purification, fuel consumption, and driving performance by paying attention to various phenomena at the time of starting the engine, HC is generated during the starting operation. Based on the mechanism of
An object of the present invention is to provide an engine control device that can maintain an optimum fuel amount and combustion.

[0008]

[Means for Solving the Problems] To achieve the above object,
The engine control device according to the present invention is provided in a multi-cylinder engine including a fuel injection valve, a fuel pressure pump, a power supply battery, a starter device, and the like, and the surrounding conditions of each part of the engine when the engine is started. Is detected, the amount of fuel required for injection is corrected and calculated based on the detected information,
It is characterized in that the fuel amount is simultaneously supplied to all the cylinders of the engine before the starter device is operated, and when the fuel amount is simultaneously injected to all the cylinders of the engine, if the fuel amount of each cylinder is different. It is characterized in that the detection of the ambient condition of each part of the engine is the detection of the battery voltage, the engine temperature, the fuel supply pressure, or the operating / rotating condition of the pump.

In addition, after the fuel is simultaneously supplied to all the cylinders, the time-series independent fuel injection is performed for each of the cylinders, and the time-series independent fuel injection is performed for each of the cylinders.
It is characterized in that fuel injection for each of the cylinders is started from the cylinder that was in the intake stroke when the simultaneous fuel is supplied to all the cylinders. Furthermore, after the starter device is in operation,
When the engine speed increase rate is detected to determine the initial explosion of the engine, and when the engine speed increase rate is below a predetermined value, fuel is simultaneously injected into all cylinders again, and at the end of the intake stroke when the engine is stopped. It is characterized in that the cylinders are identified and stored, and when the simultaneous injection is performed at the next engine start, the injected fuel amount is sequentially reduced according to the air filling rate of each cylinder.

The engine control device according to the present invention constructed as described above monitors the state of each cylinder of the engine from the initial stage of rotation at the time of starting the engine so as to ensure effective combustion at the time of starting. Fuel supply at engine start,
And, it accurately controls the supply timing.Specifically, the operation of the starter device is performed based on the behaviors of the power supply battery, the starter device, and the fuel pump for fuel pressure feeding when the ignition switch is operated. The fuel is injected and supplied to all the cylinders of the engine at the same time, and then the cylinders are discriminated and the fuel is supplied in time series.

According to the present invention, by the control,
The influence of the battery voltage drop can be reduced, the HC generated at the time of starting can be significantly reduced, and the starting time can be shortened. Immediately after the engine is started, the first cylinder that enters the intake stroke is determined, and the minimum amount of fuel required for combustion is supplied to determine the HC emission amount.
It is possible to reduce by 50% or more. That is,
70% or more (during mode operation) is discharged, the amount of HC at the time of start can be significantly reduced, the source of air pollutants such as smog can be reduced, and it is useful for improving fuel efficiency and drivability. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of an engine and an engine control device of this embodiment. Each cylinder 4 of the multi-cylinder engine 1 has a piston 2,
There is a combustion chamber 4a composed of a cylinder 3, and the combustion chamber 4a
An intake pipe 9 and an exhaust pipe 13 are connected to the upper part of a, and a connection portion between the intake pipe 9 and the combustion chamber 4a and a connection portion between the exhaust pipe 13 and the combustion chamber 4a are An intake valve 5 and an exhaust valve 6 are attached respectively. The intake valve 5
The air-fuel mixture introduced into the combustion chamber 4 via the spark plug 7
After being ignited and burned by, it is discharged to the exhaust pipe 13 through the exhaust valve 6.

Further, a plurality of cylinders 4, 4, ... Are arranged in the engine 1, and a fuel injection valve 10 for measuring and injecting fuel is provided in each cylinder 4 ,. 5, the fuel is directly injected and supplied into each of the cylinders 4, 4, ... At an optimum timing based on a command from the controller 15. When supplying fuel, the fuel tank 28
Fuel is pressurized to a constant fuel pressure by the fuel pump 26 and supplied.

A throttle valve 11 that rotates in response to the movement of an accelerator pedal (not shown) of an automobile or the like and a throttle valve angle sensor 23 that detects the opening of the throttle valve 11 are mounted on the intake pipe 9. The signal detected by the valve angle sensor 23 is input to the controller 15 and is calculated to estimate the load of the engine 1. The rotation of the engine 1 is determined by the crank angle sensor 12
Calculated by the controller 15 based on the signal detected by

An air flow sensor 8 is attached to the intake pipe 9, while the exhaust pipe 1 is attached to the exhaust pipe 13.
Oxygen concentration sensor 1 that measures the air-fuel ratio from the oxygen concentration in 3
4 is attached. The detection signal of the air flow sensor 8 and the detection signal of the oxygen concentration sensor 14 are taken in by the controller 15, processed by the air-fuel ratio arithmetic circuit 16 in the controller 15, and then calculated by the general arithmetic unit 17. After the calculation, the fuel injector command circuit 18,
Ignition device command circuit 19 and EGR device command circuit 27
A command is issued to each device to optimally control each device.

Here, the controller 15 obtains a signal from the fuel pressure sensor 20 provided on the way of the fuel line 24 and controls and corrects the fuel amount based on the fuel pressure signal so that early start can be achieved. To do. Further, the exhaust gas discharged from the engine 1 is discharged to the outside air from the exhaust tail pipe 22 via the catalyst device 21 mounted on the way of the exhaust pipe 13. When the engine is started, the catalyst device 21
Cannot be warmed up sufficiently and is not activated.
It is difficult to purify harmful exhaust components such as CO.

After the engine is warmed up, the oxygen concentration sensor 1 is
Based on the signal of No. 4, the controller 15 controls the fuel amount, and controls the fuel amount and the ignition timing for maintaining the conversion efficiency of the catalyst. Furthermore, because the combustion temperature increases,
Since a large amount of nitrogen oxides (called NOx) is discharged, the opening area of the EGR valve 27 is controlled by the controller 15 based on the signal from the air flow sensor 8 and the signal from the intake pipe pressure sensor 25.
Is controlled and metered by the EGR device command circuit 33 to recirculate a part of the exhaust gas into the intake pipe 9, and the combustion temperature is lowered to reduce the NOx emission amount based on the burned gas mixing effect.

A starter device 29 is arranged in the crank portion, and the engine 1 is started based on a command from the starter device command circuit 30. The controller 15 and the starter device 29 are driven by electric power supplied from a battery 31, and are connected so that a start start signal of the ignition key 32 is input to the general calculation section 17.

An intake pipe pressure sensor 25 for measuring the pressure in the intake pipe 9 is added to the intake pipe 9. The pressure sensor 25 is a sensor necessary for estimating the air filling rate in the intake pipe at the time of starting the engine and supplying an appropriate amount of fuel to each cylinder. As an alternative method, it goes without saying that the rate of increase in the engine speed can be predicted by the signal change of the crank angle sensor 12.

The present invention specifically shows the contents related to the calculation and processing after guiding the signals of the respective devices and sensors in the engine starting state to the controller 15 and the control of the engine accessories. In the total calculation unit 17 inserted in the controller 15, constants required for proper control of the fuel injection valve 10 at the time of starting are stored, and at the time of cranking the engine 1, the intake stroke state is first set ( (Or comes) Information that distinguishes cylinders is stored.

The controller 15 is supplied with power from the battery 31. Hereinafter, achievement of early engine start will be described. FIG. 2 is a flowchart showing the engine control process at the time of starting. The ignition key 3 is used to start the engine 1 of an automobile or the like.
When the control device 2 is operated to start the control, before the starter device 29 is rotated, first, the battery voltage is read and the temperature around the engine and the fuel pressure are detected in steps S1 to S3. The amount of fuel commensurate with the pressure is calculated by the controller. Next, the specific fuel amount obtained by the calculation is injected once into all cylinders simultaneously. Then, in step S5, the starter device 29 is operated, the crank of the engine 1 starts to rotate, and each piston 2, 2 ... In each cylinder 4, 4 ... At the same time, the cylinder discrimination is performed, the supply of fuel for each cylinder is started, and the engine control at the time of start is ended.

The engine control at the time of starting is such that when the starter device 29 starts to rotate, the voltage of the battery 31 drops due to the rotation, and the fuel pump 26 driven by the battery 31 can operate normally. This is done because it becomes difficult to supply the necessary fuel from the injection valve 10 because the fuel pressure also decreases due to the disappearance, and it is necessary to avoid deterioration of the fuel metering accuracy. By measuring the first fuel before the starter device 29 is operated, the accuracy of fuel injection can be maintained high,
In addition, it is possible to achieve an early start of the engine 1.

Instead of the fuel pressure sensor 20, the control unit 15 may monitor the operation and rotation of the fuel pump 26. FIG. 3 is a diagram showing the stroke of each cylinder after the engine is started. According to the invention, the engine 1
When the ignition key 32 is turned on, ambient temperature conditions such as the temperature around the engine and fuel pressure are detected by the respective sensors and input to the engine controller 15. Based on this information, the starter device 29 is activated before starting operation. The fuel is injected into all cylinders at the same time, and then the cylinder immediately before the intake stroke is determined in order to supply the fuel to each cylinder separately. Is jetted and supplied to the section. The fuel quantity at the time of the simultaneous injection is metered and injected by correcting the opening time width of the injection valve according to the engine cooling water temperature, the ambient temperature and the battery voltage.

Further, FIG. 4 illustrates the state of the first fuel supply for simultaneous injection, and shows the case where the fuel amount for each cylinder is supplied while the injection valve opening width is changed.
That is, if the first explosion is the first cylinder, the air filling rate of the next cylinder will decrease, so the fuel supply amount must be reduced. FIG. 5 compares the injected fuel pressure drop in the case where the fuel injection valve 10 is opened after the starter operates during the actual start-up with the degree of the injected fuel pressure in the case where the fuel injection valve opens before the starter operates. It was done. The drop in the injected fuel pressure depends on the drop in the battery voltage, and the once dropped voltage does not easily recover, and does not recover to the normal battery voltage even at the time of injection for each cylinder. Since the battery voltage drops due to the starter operation, it can be said that if the fuel is metered before the starter operates, the voltage drop will be smaller and the fuel metering accuracy will be higher. Normally, the fuel pressure P is about 2.5 kg / cm ² , and the metering of the fuel is determined by the opening time width of the fuel injection valve 10. It is necessary to correct the width T by increasing it. The correction amount can be detected by the amount of electric power applied to the fuel pressure sensor 20 or the injection pump 26.
In the case of the fuel pressure sensor 20, it can be executed by increasing T when P becomes smaller in the equation PT = G (constant).

FIG. 6 is a flow chart showing another process of engine control at the time of starting. The ignition key 32 is used to start the engine 1 of a car or the like.
When the control is started by operating, the key signal of the ignition key 32 is transmitted to the engine control unit 1
By inputting to 5, the engine peripheral information such as the ambient temperature and the fuel pressure is read in step S7, and the initial fuel amount required for the simultaneous injection is calculated based on the read. In step S8, it is determined which cylinder is in the intake stroke when the engine is started.

When a cylinder with an engine first detonates, the engine speed increases at once, so the amount of air sucked into the cylinder changes over time, the pressure in the intake pipe becomes negative, and the air filling rate in the cylinder is increased. Goes down. It is necessary to control the fuel amount in order to adjust the different air amount for each cylinder to a predetermined air-fuel mixture concentration. In the first cycle, it is necessary to make the amount of fuel supplied to the cylinder in the intake stroke different from the amount of fuel supplied to the cylinder in the next intake stroke. Therefore, step S
In No. 9, when the simultaneous fuel injection of each cylinder is performed, the fuel amount is changed for each cylinder and the fuel is injected.

After the simultaneous injection, the starter device 29 is operated in step S10, and the engine 1 starts rotating. Since the rotation speed increases when there is an initial explosion, in step S11, the increase rate of the rotation speed of the engine 1 is detected, and if it is higher than a certain specific rotation speed increase rate dN / dt (for example, 200 rpm / min or more), the initial explosion speed is set. Is determined to have occurred, the process proceeds to step S12. At step S11, the rotation increase rate dN of the engine 1 is increased.
When / dt is smaller than the predetermined value, it is determined that the initial explosion does not occur, the process returns to step S9, the simultaneous injection is performed again, and the process proceeds to step S10. The presence or absence of the initial explosion can be determined even by the pressure change in the intake pipe. That is, engine 1
Since the intake pipe pressure sharply decreases in response to the increase rate of the engine speed, the intake pipe pressure sensor 8 can detect it. Whether or not the first explosion has occurred can be determined.

In step S12, cylinder discrimination is performed again in the case where the simultaneous injection in step S9 is repeated many times, and in step S13, fuel supply for each cylinder is started and started. End the engine control at the time. Next, when starting the multi-cylinder engine 1,
A means for determining which cylinder is immediately before intake will be described.

As shown in FIG. 7, in engine control, the signal from the crank angle sensor 12 of the engine (see FIG. 7).
(b)) and the top dead center signal TDC (Fig. 7 (a)) are always monitored. As shown in FIG. 7 (a), when the ignition key 32 of the engine is changed from on to off, that is, when the engine is stopped, the engine rotates by a certain crank angle due to inertia, and the crank angle at the moment when the rotation stops is The rotation is advanced compared to the crank angle when the ignition key 32 is turned off. However, when the engine is on the verge of being stopped, a specific cylinder among the multi-cylinders (four cylinders in FIG. 7) is always in the compression stroke (cylinder 3 in FIG. 7 (c)). This cylinder may be pushed down and stopped by the compression pressure generated at. That is, the crank angle may be reversed. In the present embodiment, a fine crank angle when the engine is stopped is not required, and it suffices to be able to determine which cylinder is immediately before the intake stroke. Therefore, the ignition key 32 o
Even after ff, the top dead center signal and the crank angle signal are counted and set, and the cylinder determination immediately after the stop is performed by the controller 15, and the cylinder immediately before the intake stroke is determined and stored in the storage device.

As another method of determining the cylinder immediately before the intake stroke, there is a method of determining which cylinder is just before the intake stroke based on the camshaft position for controlling the intake and exhaust valves. FIG. 8 is a flowchart of a method for determining the cylinder immediately before the intake stroke from the camshaft position for controlling the intake and exhaust valves. Engine 1
In step S14, it is detected that the ignition key has been turned on to input the value into the controller 15, and the process proceeds to step S15. In step S15, the crankshaft position information after the last engine stop is called, the cylinder on the verge of the intake stroke is determined, and the process proceeds to the next step S16. In step S16, the starter device 29 is operated to rotate the engine 1. In step S17, the first one revolution of the engine 1 is operated so as to stop the fuel injection, and in step S18, the fuel injection valves are sequentially synchronized with the intake stroke for each cylinder from the next two revolutions. Command to supply fuel from 10. Regarding the fuel amount for each cylinder, the fuel amount is measured and injected for each cycle.

After the engine is stopped, the switch (stop) signal of the ignition key is first determined in step S19, and the process proceeds to step S20. In step 20, it is determined immediately after the engine rotation is stopped, the cylinder state (signals of top dead center, crank angle, etc.) at that time is searched and set, and the cylinder immediately before the intake stroke is determined from the signal and stored in the storage device. Put. Next, in step S21, a specific next engine start fuel starting cylinder is stored for the next engine start, and the flow is ended. At the next engine start, fuel is sequentially supplied from the stored cylinders based on the requested fuel amount for each cylinder based on a command from the controller 15.

[0032]

As can be understood from the above description, the engine device according to the present invention measures the fuel before the starter device is operated and achieves simultaneous combustion in each cylinder in order to achieve complete combustion at the engine start. By injecting and supplying fuel,
The influence of the battery voltage drop can be reduced, the HC generated at the time of starting can be significantly reduced, and the starting time can be shortened.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an engine including an engine control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a flowchart of fuel injection and starter device operation at the time of engine start.

FIG. 3 is a (basic) relationship diagram showing a stroke of each cylinder of the engine and a fuel injection state.

FIG. 4 is a (application) relationship diagram showing a stroke and a fuel injection state of each cylinder of the engine.

FIG. 5 is a diagram showing a behavior of a fuel supply pressure when the engine is started.

FIG. 6 is a view showing another flowchart of fuel injection and starter device operation at the time of engine start.

FIG. 7 is a diagram showing a top dead center signal, a crank angle signal, and a stop position of each cylinder immediately after the engine rotation is stopped.

FIG. 8 is a diagram showing a flowchart for selecting a fuel injection cylinder when the engine is started.

[Explanation of symbols]

1 Engine 10 Fuel Injection Valve 2 Piston 11 Throttle Valve 3 Cylinder 12 Crank Angle Sensor 4 Combustion Chamber 13 Exhaust Pipe 5 Intake Valve 14 Oxygen Concentration Sensor 6 Exhaust Valve 15 Controller 7 Spark Plug 20 Fuel Pressure Sensor 8 H / W Sensor 25 Intake Pipe Pressure sensor 9 Intake pipe

Claims (7)

[Claims] 1. A control device for a multi-cylinder engine including a fuel injection valve, a fuel pressure pump, a power supply battery, a starter device, etc., for detecting an ambient condition of each part of the engine at engine start,
A control device for a multi-cylinder engine, which corrects and calculates a fuel amount required for injection based on the detection information, and simultaneously supplies the fuel amount to all cylinders of the engine before the starter device operates. 2. The method according to claim 1, wherein the detection of the ambient condition of each part of the engine is detection of the battery voltage, the engine temperature, the fuel supply pressure, or the operation / rotation condition of the pump. Control device for cylinder engine. 3. A control device for a multi-cylinder engine including a fuel injection valve, a fuel pressure pump, a power supply battery, a starter device, etc., in which fuel is simultaneously injected into all cylinders of the engine before the starter device is activated. In doing so, the control device for the multi-cylinder engine is characterized in that the fuel amount for each cylinder is made different. 4. The control of a multi-cylinder engine according to claim 1, wherein time-series independent fuel injection is performed for each of the cylinders after fuel is simultaneously supplied to all of the cylinders. apparatus. 5. After the starter device is activated, the rate of increase in engine speed is detected to determine the initial explosion of the engine, and when the rate of increase in engine speed is below a predetermined value, the fuel is simultaneously supplied to all cylinders. The multi-cylinder engine control device according to claim 1 or 3, wherein injection is performed. 6. In the time-series independent fuel injection for each of the cylinders, the fuel injection for each of the cylinders is started from the cylinder that was in the intake stroke when the simultaneous fuel is supplied to all of the cylinders. The control device for a multi-cylinder engine according to claim 4. 7. When the engine is stopped, the last cylinder in the intake stroke is determined and stored, and when performing simultaneous injection at the next engine start, the amount of fuel to be injected is sequentially reduced according to the air filling rate of each cylinder. The control device for a multi-cylinder engine according to any one of claims 3 to 6, wherein: