DE10303765B4 - collectors injection - Google Patents

Abstract

A collector injection system used in an internal combustion engine (1), the collector injection system comprising: a collector (2) for pressurizing and storing high-pressure fuel at a pressure for injecting the fuel; a fuel supply pump (3) provided by the internal combustion engine (1); a fuel injection valve (5) provided for each cylinder of the internal combustion engine (1) and for supplying high-pressure fuel stored in the accumulator (2) is driven to apply a pressure for pumping the intake fuel into the accumulator (2) to which cylinder is used by injecting the high-pressure fuel into the cylinder; fuel pressure detecting means for detecting a pressure of the fuel expelled by the fuel supply pump (3); an overlap time segment calculating means for calculating an overlap time segment during which a pumping duration of the fuel supply pump (3) overlapping a fuel injection period of the fuel injection valve; a second fuel injection duration determining means for determining a fuel injection duration of the cylinder of the internal combustion engine for which the pumping duration overlaps the fuel injection period from the target fuel injection volume, the detected fuel pressure and the overlap time segment, wherein the first fuel injection duration determination means finds a first fuel injection period by using a basic map is defined by the target fuel injection volume and the detected fuel pressure; and the second fuel injection duration determination means finds a second fuel injection duration by correcting the first fuel injection duration found by the first fuel injection duration determination means according to the overlap time segment.

Description

The present invention relates to a collector injection system for storing a high-pressure fuel volume discharged from a header through a fuel supply apparatus such as a supply pump and supplying high-pressure fuel stored in the accumulator through a fuel injection valve to each cylinder of an internal combustion engine such as a multi-cylinder diesel engine.

As a conventional fuel injection system for an internal combustion engine, such as a multi-cylinder diesel internal combustion engine, a common rail common rail injection system, a plurality of fuel injection valves, and a supply pump is known. The common rail is used as a collector for pressurizing and storing high-pressure fuel at a pressure at which the fuel is injected to a cylinder of the internal combustion engine. The fuel injection valves are each represented by a solenoid fuel injection valve mounted on each cylinder of the internal combustion engine. The feed pump serves as a fuel supply pump for applying pressure to the fuel entering a pressure chamber of the fuel supply pump from a tank through an electromagnetic pump valve and pressurizing the fuel while supplying the fuel to the common rail (specifically, discharging the fuel).

In the conventional accumulator injection system, however, with the fuel injection duration of a fuel injection valve overlapping the pumping period of the supply pump, the injection pressure and the fuel injection rate are higher than in the case where the fuel injection duration of the fuel injection valve does not overlap the pumping duration of the supply pump. As a result, an actual fuel injection volume increases to a value exceeding a target fuel injection volume set according to an operating condition of the internal combustion engine. The pumping duration of the delivery pump is defined as a period of time between a pump duration start phase and a pump duration end phase. The fuel injection volume is the volume of fuel that is injected into a cylinder of the internal combustion engine.

In the case of synchronous injection, such as one injection per pumping operation, the fuel injection duration of a fuel injection valve may or may not overlap the pumping duration of the supply pump depending on the pump duration end phase. In the case of asynchronous injection, such as two injections per pump operation or six injections for four pump operations, there is a cylinder in which the fuel injection duration of a fuel injection valve overlaps the pumping duration of the supply pump and a cylinder in which the fuel injection duration of a fuel injection valve the pumping time of the feed pump does not overlap.

Thus, the fuel injection volume, in particular the volume of the fuel injected into a cylinder of the internal combustion engine in which the fuel injection duration of a fuel injection valve overlaps the pumping duration of the supply pump, is different from the fuel injection valve in which the fuel injection duration of a fuel injection valve does not overlap the pumping duration of the supply pump. which causes adverse effects on the accuracy of the control of the fuel injection volume and deteriorates the volume.

On the other hand, a collector injection system has a structure in which, to achieve a target common rail fuel pressure, a line flow flowing to a pump control valve is adjusted to control a pumping volume defined as the volume of the fuel expelled by the fuel supply pump. Also, a method for finding a pumping volume based on the magnitude of a line current flowing to the pump control valve for setting the pumping volume of the fuel discharged by the fuel supply pump by adjusting the opening of the pump control valve is known. Thus, the magnitude of a line current flowing to the pump control valve may be considered as an instruction pumping volume. However, the method for finding the pumping volume based on the magnitude of the line current flowing to the pump control valve introduces an error caused by factors including differences among the fuel supply pumps, the condition of the fuel including the viscosity, and the air , As a result, there is a problem that the precision at which the pump volume is found is poor.

While a pump drive shaft of the fuel supply pump rotates in synchronism with the crankshaft of the engine, it is impossible to fail the assembly of the engine To detect fuel supply pump with the crankshaft of the internal combustion engine, if it exists. A failure of the fuel supply pump assembly with the engine crankshaft results in a problem that the effect of fuel injection correction according to the overlap time segment described above is small even if the overlapping time segment is known in advance, for example, from an experiment or the like is.

DE 602 26 091 T2 is a prior art document according to §3 (2) PatG and shows a collector injection system used in an internal combustion engine, the collector injection system comprising: a collector for pressurizing and storing high-pressure fuel at a pressure for injecting the fuel; a fuel supply pump driven by the internal combustion engine to apply a pressure to pump the collected fuel into the accumulator; a fuel injection valve provided for each cylinder of the internal combustion engine and for supplying high-pressure fuel stored in the accumulator to the cylinder by injection of the high-pressure fuel into the cylinder; a fuel pressure detecting means for detecting a pressure of the fuel discharged by the fuel supply pump; an overlap time segment calculator for calculating an overlap time segment during which a pump duration of the fuel supply pump overlaps a fuel injection period of the fuel injection valve; a first fuel injection duration determination means for determining a fuel injection duration of the cylinder of the internal combustion engine for which the pumping duration of the fuel supply pump does not overlap the fuel injection period of the fuel injection valve, a target fuel injection volume set according to an operating condition of the internal combustion engine, and a fuel pressure detected by the fuel pressure detection device; and second fuel injection duration determination means for determining a fuel injection duration of the cylinder of the internal combustion engine for which the pumping duration overlaps the fuel injection period from the target fuel injection volume, the detected fuel pressure and the overlap time segment.

It is the object of the present invention to provide a collector injection system, with the output of cylinders of an internal combustion engine can be adjusted to the same extent and thus can be reduced or avoided vibrations and emissions of the internal combustion engine.

The object of the present invention is achieved by a collector injection system having the features of the independent claims.

Advantageous developments of the present invention are the subject of the dependent claims.

It is an advantage of the present invention to provide a fuel injection system capable of precision in controlling a fuel injection volume of each cylinder of an internal combustion engine by eliminating differences in a fuel injection volume between a cylinder in which the fuel injection duration of a fuel injection valve is the pumping duration of a fuel supply pump overlaps, and to provide a cylinder in which the fuel injection duration of a fuel injection valve does not overlap the pumping duration of the fuel supply pump.

It is further an advantage of the present invention to provide a collector injection system capable of precision for controlling a fuel injection volume of a specific cylinder of an internal combustion engine by eliminating differences in fuel injection volume between a case where the fuel injection duration of a fuel injection valve is the pumping duration a fuel supply pump at a certain cylinder overlaps, and a case in which the fuel injection duration of a fuel injection valve does not overlap the pumping duration of the fuel supply pump at the same specific cylinder, to improve.

It is further an advantage of the present invention to provide a collector injection system capable of detecting a cam phase of a fuel supply pump, and more particularly, a pump duration start phase and a pump duration end phase with high precision, and capable of detecting the detected phases the executed thereon engine control.

It is further an advantage of the present invention to provide a collector injection system capable of detecting, with high precision, an overlap time segment between the fuel injection duration of a fuel injection valve and the pumping duration of a fuel supply pump.

It is further an advantage of the present invention to provide a collector injection system capable of controlling a fuel injection volume according to an overlap time segment during which Fuel injection duration of a fuel injection valve overlaps the pumping duration of a fuel supply pump to correct with high precision.

It is further an advantage of the present invention to provide a collector injection system capable of calculating a pumping volume of a fuel supply pump with high precision.

It is further an advantage of the present invention to provide a collector injection system capable of detecting an assembly failure of a fuel supply pump.

According to the present invention, when a cylinder in which the fuel injection duration of a fuel injection valve overlaps the pumping duration of a fuel supply pump and a cylinder in which the fuel injection duration of a fuel injection valve does not overlap the pumping duration of the fuel supply pump are known in advance, a fuel injection duration of the cylinder in which the fuel injection duration of a fuel injection valve does not overlap the pumping duration of the fuel supply pump, a target fuel injection volume set according to an operating condition of the internal combustion engine, and a fuel pressure detected by a fuel pressure detection device. On the other hand, a fuel injection duration of the cylinder in which the fuel injection timing of a fuel injection valve overlaps the pumping duration of the fuel supply pump is found from a target fuel injection volume, a detected fuel pressure and an overlap time segment of the fuel injection duration of a fuel injection valve and the pumping duration of the fuel supply pump.

Thus, it is possible to reduce a difference in the fuel injection volume between a cylinder in which the fuel injection duration of a fuel injection valve overlaps the pumping duration of the fuel supply pump and a cylinder in which the fuel injection duration of a fuel injection valve does not overlap the pumping duration of the fuel supply pump. In addition, it is also possible to suppress differences in combustion performance between the cylinders of the internal combustion engine. Furthermore, it is also possible to prevent emission deterioration.

According to the present invention, it is possible for a specific cylinder of the internal combustion engine, a difference of the actual fuel injection valve between a case in which the fuel injection duration of a fuel injection valve overlaps the pumping duration of the fuel supply pump in the particular cylinder, and a case in which the fuel injection duration of a fuel injection valve Pumping time of the fuel supply pump at the same particular cylinder does not overlap, decrease.

According to the present invention, a change of the fuel pressure detected by a fuel pressure detecting means exceeding a predetermined value is detected as an event in which a cam phase of the fuel supply pump can be regarded as a pump duration start phase. A change of the fuel pressure detected by the fuel pressure detecting means, which becomes smaller than the predetermined value after exceeding the predetermined value, is detected as an incident in which a cam phase of the fuel supply pump can be regarded as a pump duration end phase. Alternatively, a pump end geometric phase is stored in the engine subassembly of the fuel delivery pump. In this way, a cam phase of the fuel supply pump and in particular a pump duration start phase and a pump duration end phase can be found with high accuracy.

A pump duration start phase and a pump end duration phase are reflected in the engine control executed after the pump duration start phase and the pump duration end phase are detected. Examples of the engine control are the fuel injection control and the pump control. For example, it is possible to identify an overlap time segment between the fuel injection duration of a fuel injection valve and the pumping duration of the fuel supply pump from the pump duration start phase and the pump duration end phase. It is then possible to execute the fuel injection control according to the overlap time segment. In addition, it is possible to find a pump volume with a high accuracy from the pump duration start phase and the pump end end phase. It is then possible to carry out the pump control according to the pumping volume.

According to the present invention, the length of the overlap time segment can be found with high accuracy from a pump duration end phase, a target fuel injection duration and a target fuel injection timing.

It is possible to find a pumping volume of the fuel pumped into a collector from the fuel supply pump based on the cam profile of the fuel supply pump (or the cam phases or the plunger positions), a pump duration start phase, and a pump duration end phase.

The amount of fuel leaking from a high-pressure pipe can be found with high accuracy, for example, from a target pumping volume of the fuel, a static injector discharge amount, and a dynamic injector discharge amount.

When the amount of outflowing fuel exceeds a predetermined value, for example, the fuel injection control for improving pump control is executed. More specifically, in the case where an abnormality occurs in the fuel supply pump, in the case where an opening abnormality occurs in a fuel injection valve or in the case where an abnormality occurs in the fuel pipe system, for example, the engine is stopped or the fuel injection control or the pump controller is executed to allow a vehicle to keep moving.

For example, it is desirable to provide an electronic control unit having a low pass filter and a high pass filter used to process an electrical signal generated by a fuel pressure sensor. By providing such filters, a process of detecting a pump duration start phase and a pump duration end phase at a high speed can be performed.

• 1 ist ein Blockdiagramm eines Kraftstoffeinspritzsystems mit gemeinsamer Leitung (Common-Rail-Kraftstoffeinspritzsystem), das durch ein erstes Ausführungsbeispiel der vorliegenden Erfindung dargestellt ist;
• 2 ist eine Grafik, die ein Kennfeld zum Ermitteln einer Basiskraftstoffeinspritzdauer bei dem ersten Ausführungsbeispiel der vorliegenden Erfindung darstellt;
• 3 ist eine Grafik, die ein Kennfeld zum Ermitteln einer Basiskraftstoffeinspritzdauer bei dem ersten Ausführungsbeispiel der vorliegenden Erfindung darstellt;
• 4 ist ein Ablaufdiagramm, das eine Kraftstoffeinspritzsteuerung darstellt, die durch das erste Ausführungsbeispiel der vorliegenden Erfindung ausgeführt wird;
• 5 ist ein Ablaufdiagramm, das eine Kraftstoffeinspritzsteuerung darstellt, die durch ein zweites Ausführungsbeispiel der vorliegenden Erfindung ausgeführt wird;
• 6 ist ein Ablaufdiagramm, das eine Kraftstoffeinspritzsteuerung darstellt, die durch das zweite Ausführungsbeispiel der vorliegenden Erfindung ausgeführt wird;
• 7 ist ein Kennfeld zum Ermitteln einer Korrekturmenge bei dem zweiten Ausführungsbeispiel der vorliegenden Erfindung;
• 8 ist ein Ablaufdiagramm, das eine Kraftstoffeinspritzsteuerung darstellt, die durch ein drittes Ausführungsbeispiel der vorliegenden Erfindung ausgeführt wird;
• 9 ist ein Ablaufdiagramm, das eine Kraftstoffeinspritzsteuerung darstellt, die durch das dritte Ausführungsbeispiel der vorliegenden Erfindung ausgeführt wird;
• 10 ist eine Grafik, die ein Kennfeld zum Ermitteln eines Pumpenausstoßvolumens bei dem dritten Ausführungsbeispiel der vorliegenden Erfindung darstellt;
• 11 ist eine Sammlung von Wellenformen, die Zeitabläufe darstellen, die für eine Kraftstoffeinspritzung bei dem dritten Ausführungsbeispiel der vorliegenden Erfindung relevant sind;
• 12 ist ein Kennfeld zum Ermitteln einer Korrekturmitte bei dem dritten Ausführungsbeispiel der vorliegenden Erfindung;
• 13 ist ein Ablaufdiagramm, das einen Vorgang zum Erfassen einer Phase einer Kraftstoffzufuhrpumpe bei dem vierten Ausführungsbeispiel der vorliegenden Erfindung darstellt;
• 14 ist ein Ablaufdiagramm, das einen Vorgang zum Erfassen des Kraftstoffauslaufens bei einem fünften Ausführungsbeispiel der vorliegenden Erfindung darstellt;
• 15 zeigt ein Zeitablaufdiagramm eines Betriebs, der durch eine Kraftstoffzufuhrpumpe bei dem fünften Ausführungsbeispiel der vorliegenden Erfindung ausgeführt wird;
• 16 zeigt ein Kennfeld zum Ermitteln einer statischen Auslaufmenge bei dem fünften Ausführungsbeispiel der vorliegenden Erfindung;
• 17 zeigt ein Kennfeld zum Ermitteln einer Korrekturmenge bei dem fünften Ausführungsbeispiel der vorliegenden Erfindung;
• 18 zeigt ein Kennfeld zum Ermitteln einer dynamischen Auslaufmenge bei dem fünften Ausführungsbeispiel der vorliegenden Erfindung;
• 19 zeigt einen Zeitablauf einer Variation des Kraftstoffdrucks der gemeinsamen Leitung bei dem fünften Ausführungsbeispiel der vorliegenden Erfindung;
• 20 ist ein Diagramm, das eine Verteilung eines Kraftstoffverbrauchs in dem fünften Ausführungsbeispiel der vorliegenden Erfindung zeigt;
• 21 ist ein Blockdiagramm, das eine Verbrennungsmotorsteuerungseinheit zeigt, die durch ein sechstes Ausführungsbeispiel der vorliegenden Erfindung implementiert ist; und
• 22 zeigt Wellenformen, die Zeitabläufe der Kraftstoffdrücke der gemeinsamen Leitung in dem sechsten Ausführungsbeispiel der vorliegenden Erfindung zeigt.

By finding a difference in a phase between a detected position of the pump duration end phase and a base position of the pump duration end phase, for example, the cam difference of the fuel supply pump can be detected from the rotation angle of the output shaft of the internal combustion engine. It is thus possible to detect an assembly phase of the fuel supply pump with high accuracy.

• 1 Fig. 10 is a block diagram of a common rail fuel injection system shown by a first embodiment of the present invention;
• 2 Fig. 15 is a graph illustrating a map for determining a basic fuel injection duration in the first embodiment of the present invention;
• 3 Fig. 15 is a graph illustrating a map for determining a basic fuel injection duration in the first embodiment of the present invention;
• 4 Fig. 10 is a flowchart illustrating a fuel injection control executed by the first embodiment of the present invention;
• 5 Fig. 10 is a flowchart illustrating a fuel injection control executed by a second embodiment of the present invention;
• 6 Fig. 10 is a flowchart illustrating a fuel injection control executed by the second embodiment of the present invention;
• 7 Fig. 11 is a map for determining a correction amount in the second embodiment of the present invention;
• 8th Fig. 10 is a flowchart illustrating a fuel injection control executed by a third embodiment of the present invention;
• 9 Fig. 10 is a flowchart illustrating a fuel injection control executed by the third embodiment of the present invention;
• 10 Fig. 15 is a graph illustrating a map for determining a pump discharge volume in the third embodiment of the present invention;
• 11 Fig. 11 is a collection of waveforms illustrating timings relevant to fuel injection in the third embodiment of the present invention;
• 12 Fig. 11 is a map for determining a correction center in the third embodiment of the present invention;
• 13 Fig. 10 is a flowchart illustrating a process for detecting a phase of a fuel supply pump in the fourth embodiment of the present invention;
• 14 Fig. 10 is a flowchart illustrating a process of detecting fuel leakage in a fifth embodiment of the present invention;
• 15 Fig. 10 is a timing chart of an operation performed by a fuel supply pump in the fifth embodiment of the present invention;
• 16 FIG. 12 is a map for determining a static leakage amount in the fifth embodiment of the present invention; FIG.
• 17 FIG. 11 is a map for determining a correction amount in the fifth embodiment of the present invention; FIG.
• 18 Fig. 13 is a map for determining a dynamic leakage amount in the fifth embodiment of the present invention;
• 19 Fig. 10 shows a timing of a variation of the common rail fuel pressure in the fifth embodiment of the present invention;
• 20 Fig. 15 is a diagram showing a distribution of fuel consumption in the fifth embodiment of the present invention;
• 21 Fig. 10 is a block diagram showing an engine control unit implemented by a sixth embodiment of the present invention; and
• 22 FIG. 12 shows waveforms showing timings of the common line fuel pressures in the sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained with reference to the accompanying drawings.

(First embodiment)

The 1 to 4 show a first embodiment of the present invention. In particular 1 a block diagram showing a structure of a common rail fuel injection system.

A common rail fuel injection system is an internal combustion engine 1 , such as a four-cylinder diesel internal combustion engine applied. The common rail fuel injection system has a common line 2 which is used as a collector in which a high-pressure fuel is collected at a pressure equal to a fuel injection pressure for injecting fuel into each cylinder. The common rail fuel injection system also has a fuel supply pump 3 for applying pressure to a fuel received therefrom and for pumping the pressurized fuel into the common conduit 2 , The common rail fuel injection system also includes a plurality of electromagnetic fuel injection valves 5 for supplying a high-pressure fuel to cylinders of the internal combustion engine 1 on, in the common line 2 is collected. Typically, the internal combustion engine has 1 four cylinders. The solenoid fuel injection valves 5 are all also referred to hereinafter as an injector or an injection device. The common rail fuel injection system is also equipped with an electronic control unit 10 for controlling the fuel supply pump 3 and the solenoid fuel injection valves 5 Mistake. In the following description, the electronic control unit 10 simply referred to as an ECU.

It is necessary to continuously pressurize the high-pressure fuel into the common rail and to store it at a pressure equal to a fuel injection pressure. For this reason, the fuel supply pump 3 for pressurizing and storing the high pressure fuel in the common conduit 2 through a high pressure pipe 11 used. At a drain pipe 14 for draining fuel from the common line 2 to a fuel tank 7 is a pressure limiter 13 to avoid a hollow pressure built-in, to prevent the fuel in the common line 2 exceeds a preset pressure limit.

The fuel supply pump 3 Also simply referred to as a feed pump is a pump for supplying fuel to the common line 2 , The fuel supply pump 3 pressurizes the fuel and discharges the high pressure fuel from an exhaust port thereof to the common one management 2 out. The fuel supply pump 3 has a pump drive shaft 16 passing through a crankshaft 15 of the internal combustion engine 1 is driven. The fuel supply pump 3 is also with a feed pump for pumping fuel from the fuel tank 7 provided when passing through the pump drive shaft 16 is driven. The feed pump is a low pressure fuel feed pump.

In addition, the fuel supply pump 3 a cam, one or more plunger and one or more cylinders. The cam will rotate through the pump drive shaft 16 driven. The plungers in turn are driven by the cam with a forward and backward movement within the cylinder. The plungers and cylinders form a pressure application chamber or plunger chamber for receiving fuel and applying pressure to the captured fuel. The fuel supply pump 3 Also has an exhaust valve which is opened when the pressure of the fuel in the pressurizing chamber reaches or exceeds a predetermined level. In addition, the fuel supply pump 3 equipped with two plungers, wherein the phases are different from each other by 180 °.

The fuel supply pump 3 is also provided with an outlet port for preventing the temperature of the fuel in a pump chamber from becoming high. Fuel leaking from the discharge port of the fuel supply pump becomes the fuel tank 7 through fuel return paths 17 and 19 recycled. At a fuel path connecting the pump chamber to the pressurization chamber at the fuel supply pump 3 linked, is an intake control valve (SCV) 4 for adjusting the opening degree (or opening) of the fuel path for changing the discharge volume (or the pump discharge volume or the pump volume) of the fuel supplied from the fuel supply pump 3 to the joint leadership 2 flows. The SCV 4 is a solenoid valve that functions as a pump discharge volume varying device or a pump volume change device.

The SCV 4 is electronically controlled by a pump drive signal provided by the ECU 10 to the SCV 4 is discharged by a pump drive circuit not shown in the figure. The SCV 4 adjusts the intake volume of the fuel to the pressurizing chamber of the fuel supply pump 3 is pulled. The SCV 4 thus changes the fuel injection pressure and therefore the pressure of the fuel in the common rail 2 , The SCV 4 is a valve of the normally open type. A normally open valve is placed in a fully open state when a current flowing to the valve is turned off. The SCV 4 is also referred to as a pump flow control valve.

At the joint line 2 is a variety of branch pipes 12 built-in. Each of the fuel injection valves 5 is at the downstream end of one of the branch pipes 12 intended. Each of the fuel injection valves 5 has a nozzle, an electromagnetic actuator and a forced means, such as a spring, for forcibly applying a pressure to a nozzle needle in a valve closing direction. The nozzle has an injection hole formed thereon. The electromagnetic actuator drives the nozzle needle in a valve opening direction.

The injection of the fuel is electronically controlled by allowing and prohibiting flow of current to a fuel control solenoid valve used as an electromagnetic actuator for controlling a pressure of the fuel in a back pressure control chamber of the nozzle needle. While the solenoid valve of a fuel injection valve 5 is in an open state, injects the fuel injection valve 5 For example, high-pressure fuel in the cylinder, with the fuel injection valve 5 is linked. Fuel coming out of a fuel injector 5 leaks and fuel returned from the back pressure control chamber flow to the fuel tank 7 through fuel return paths 18 and 19 ,

The ECU 10 has a microcomputer of a well-known construction having a structure having functions of a CPU, a memory unit, an input circuit, an output circuit, a power supply circuit, an injector drive circuit and a pump drive circuit. The CPU performs processes such as control and general processes. The storage unit used for storing a plurality of programs and various types of data is typically a ROM and / or a RAM. Sensor signals generated by various sensors and a signal generated by an A / D converter as a result of an A / D process are supplied to the microcomputer.

The common rail fuel injection system has a cylinder determination device that includes a cylinder determination sensor 31 having. The cylinder determination sensor 31 includes one Signal rotor, a plurality of cylindrical teeth (or protrusions) and an electromagnetic transducer. The signal rotor rotates with the rotation of the camshaft. For example, the signal rotor makes one revolution while the crankshaft 15 makes two turns. On the outer periphery of the signal rotor cylinder teeth are provided, which are each associated with a cylinder. The electromagnetic pickup generates cylinder determination signal pulses according to the distance of the cylinder teeth. More specifically, when the piston of the first cylinder reaches a position immediately before the fuel injection, a base cylinder designation signal pulse having a large pulse width is output. Later, when the piston of the third cylinder reaches a position immediately before the fuel injection, a cylinder determination signal pulse having a small pulse width is output. Then, when the piston of the fourth cylinder reaches a position immediately before the fuel injection, a cylinder determination signal pulse having a small pulse width is output. Subsequently, when the piston of the second cylinder reaches a position immediately before the fuel injection, a cylinder determination signal pulse having a small pulse width is output. These pulses are referred to as the G signal.

The common rail fuel injection system also has a speed detector that includes a crank angle sensor 32 having. The crank angle sensor 32 has a signal rotor, a plurality of crank angle detection teeth (or protrusions) and an electromagnetic pickup. The signal rotor rotates synchronously with the rotation of the crankshaft 15 , For example, the signal rotor makes a turn while the crankshaft 15 makes a turn. The crank angle detection teeth are provided on the outer periphery of the signal rotor. The electromagnetic pickup generates NE signal pulses according to the distance to the crank angle detection teeth. The crank angle sensor 32 generates a plurality of NE signal pulses while the signal rotor makes a turn. By measuring intervals between the NE signal pulses, the ECU finds 10 an engine speed NE on.

The common rail fuel injection system also has an accelerator sensor 33 for detecting an opening ACCP of an accelerator pedal. In addition, the common rail fuel injection system also has a water temperature sensor 34 for detecting a cooling water temperature THW of the internal combustion engine 1 , Further, the common rail fuel injection system also has a fuel pressure detection sensor 35 for detecting a fuel pressure Pc of the fuel in the common rail 2 , In addition, the common rail fuel injection system also has a fuel temperature sensor 36 for detecting a fuel temperature THF.

The ECU 10 finds a fuel pressure optimum of the common line for an operating condition of the internal combustion engine 1 on. The ECU 10 has a discharge volume controller (or SCV controller) for driving the SCV 4 , More precisely, the ECU finds 10 a target fuel pressure Pt of the common rail from information about an operating state of the internal combustion engine 1 on. The information includes an engine speed NE and an accelerator opening ACCP. The ECU 10 Sets a pump drive signal to the SCV 4 is supplied to make the common rail fuel pressure Pc equal to the common rail target fuel pressure Pt. The pump drive signal represents the magnitude of a current that the SCV 4 drives, or the size of an SCV line current.

It is desirable to have the pump drive signal to the SCV 4 is introduced to introduce into a feedback control to the fuel pressure Pc of the common line passing through the fuel pressure sensor 35 the common line is detected to make the target fuel pressure Pt equal to the common line. It should be noted that it is desirable to perform a duty control as a control of the pump drive signal given to the SCV 4 is supplied. In other words, the duty ratio of the pump drive signal in accordance with the target common rail fuel pressure Pt becomes a duty control for changing the opening of the SCV 4 set. In this way, digital control can be performed with high accuracy. The duty ratio is as a ratio of the duty of the pump drive signal to the switch-off of the pump drive signal.

The ECU 10 has a controller for executing a fuel injection duration control and a fuel injection timing control for the fuel injection valve 5 every cylinder. The controller has a fuel injection volume determination means and a fuel injection timing determination means for determining an optimum target fuel injection volume Q (or an optimal current supply period) for an operating state of the internal combustion engine and a fuel injection timing T (or a power supply start timing). The control means also has fuel injection duration determination means for finding a fuel injection instruction pulse period Tq (or a fuel injection instruction pulse width or a fuel injection instruction pulse duration) according to an operation state of the internal combustion engine 1 , a fuel pressure Pc In addition, the controller also has a fuel injection valve driving means for applying a pulse fuel injection valve driving current (a fuel injection instruction pulse) to the electromagnetic valve of the fuel injection valve 5 each cylinder through a fuel injection valve drive circuit.

For example, the ECU finds 10 a target fuel injection volume Q for an operating state of the internal combustion engine 1 , In this case, the operating state is represented by an engine speed NE, an accelerator opening ACCP and a water temperature THW. Then the ECU finds 10 a fuel injection instruction pulse period Tq from the common rail fuel pressure Pc and a target fuel injection volume Q.

An operating state detecting device for detecting an operating state of the internal combustion engine 1 may include an intake air flow sensor, an intake air temperature sensor, an intake air pressure sensor, a fuel temperature sensor, and a fuel injection volume sensor. The target fuel injection volume Q, the fuel injection timing T and the target common rail pressure Pt may be corrected according to signals generated by these sensors.

In the common rail fuel injection system implemented by this embodiment, two injections are made per pump operation. A pumping duration of an operation for pumping fuel by raising a first plunger of the fuel supply pump 3 overlaps a fuel injection duration of the fuel injection valve 5 of the second cylinder. In addition, a pumping duration of an operation for pumping fuel by raising a second plunger overlaps the fuel supply pump 3 a fuel injection duration of the fuel injection valve 5 of the third cylinder. The fuel injection duration of each of the fuel injection valves 5 of the first and fourth cylinders do not overlap pumping time. The fuel supply pump 3 is with the internal combustion engine 1 so that the above relationships between the fuel injection duration and the pumping duration are given.

The ECU 10 This embodiment performs control for suppressing a difference in the fuel injection volume between a cylinder in which a pumping duration overlaps the fuel injection duration and a cylinder in which a pumping duration does not overlap the fuel injection duration. More precisely, the ECU 10 for the execution of this control, first and second fuel injection duration determination means. The first fuel injection duration determination means detects a first basic fuel injection duration Tqa for cylinders in which a pump duration does not overlap a fuel injection duration, from an in 2 shown first basic map. The cylinders in which one pump duration does not overlap the fuel injection duration from a first basic map are the first and fourth cylinders. On the other hand, the second fuel injection duration determination means finds a second basic fuel injection duration Tqb for cylinders in which a pump duration overlaps a fuel injection duration from an in 3 shown second basic map. The cylinders in which one pump duration overlaps the fuel injection duration from a first base map are the third and second cylinders. It should be noted that, as in the 2 and 3 is shown, the second basic fuel injection duration Tqb for a target fuel injection volume Q is shorter than the basic fuel injection duration Tqa for the same target fuel injection volume Q.

The following description will explain the fuel injection volume control method of a fuel injection valve in this embodiment. 4 Fig. 10 is a flowchart illustrating the fuel injection volume control. A routine through the flowchart in 4 is repeatedly executed at predetermined timings after an ignition switch is turned on, which is not shown in any of the figures.

The flowchart starts with step S1 for determining whether the crank angle of the engine 1 with a control reference position for executing the fuel injection volume control of the fuel injection valve 5 coincide or not, which is on a predetermined cylinder, for example, the k-th cylinder mounted. If the result of the determination is NO, the control of the execution is returned to the calling routine. For example, the fuel injection volume control of the fuel injection valve 5 mounted on the k-th cylinder just after the end of the volume injection of the fuel injection valve 5 which is mounted on the k-th cylinder to be started in the previous cycle. As an alternative, the fuel injection volume control of the fuel injection valve 5 mounted on the k-th cylinder just after the end of the volume injection of the fuel injection valve 5 , which is in front of a cylinder the kth cylinder in the order of injections in the same cycle to be started. If the kth cylinder is the first cylinder, the cylinder immediately before the kth cylinder in the order of the injections is the second cylinder. When the k-th cylinder is the third cylinder, the cylinder immediately before the k-th cylinder in the order of the injections is the first cylinder. When the k-th cylinder is the fourth cylinder, the cylinder immediately before the k-th cylinder in the order of the injections is the third cylinder. If the kth cylinder is the second cylinder, the cylinder immediately before the kth cylinder in the order of injections is the fourth cylinder.

When the determination result obtained at step S1 is YES, on the other hand, the flow of control goes to step S2 where engine parameters such as the G signal, the NE signal, and the accelerator opening signal (ACCP signal) are input , Specifically, the NE signal and the accelerator opening signal (ACCP signal) are required for finding a target fuel injection volume Q and a target fuel injection timing T. Then, at the next step S3, a target fuel injection volume Q of the NE signal and the accelerator opening signal (ACCP signal) is found. Subsequently, at the next step S4, a target fuel injection timing T from the NE signal and the accelerator opening signal (ACCP signal) is found. Then, at the next step S5, the common line fuel pressure Pc is input.

Subsequently, the flow of the control proceeds to step S6 to identify the k-th cylinder to be injected with fuel based on the G and NE signals. Then, the flow of the control proceeds to step S7 to determine whether the k-th cylinder identified in step S6 is a cylinder in which a pumping duration overlaps a fuel injection duration, or a cylinder in which a pumping duration does not overlap a fuel injection duration. When the result of the determination is NO, particularly when the k-th cylinder is a non-overlapping cylinder which is a cylinder in which a pumping period does not overlap a fuel injection period, the control proceeds to step S8. At step S8, a first basic fuel injection duration Tqa is found by using the first basic map representing a relationship between the target fuel injection volume Q, the common rail fuel pressure Pc, and the first base fuel injection duration Tqa. The first map was typically determined in advance from results of an experiment. In this embodiment, the cylinders each having a pumping duration that does not overlap a fuel injection period are the first and fourth cylinders. Then, the flow of the control proceeds to step S10.

On the other hand, when the determination result obtained in step S7 is YES, particularly when the k-th cylinder is an overlapping cylinder defined as a cylinder in which a pumping duration overlaps a fuel injection period, the flow of the control proceeds to step S9. At step S9, a second basic fuel injection duration Tqb is found by using the second basic map representing a relationship between the target fuel injection volume Q, the common rail fuel pressure Pc, and the second basic fuel injection duration Tqb. The second baseline map was determined in advance typically from results of an experiment. In this embodiment, the cylinders each having a pumping duration overlapping a fuel injection period are the third and second cylinders. It should be noted that, as an alternative, a second basic fuel injection duration Tqb is found for a calculated overlap time segment t, which is the portion of the pump duration that overlaps the fuel injection duration.

The flow of control then proceeds from step S8 or S9 to step S10, at which the target fuel injection duration T is converted to a final fuel injection timing TFIN. In addition, the final fuel injection timing TFIN and the first base fuel injection duration Tqa or the second base fuel injection duration Tqb are converted into fuel injection volume instruction values, specifically, a valve opening instruction value and a valve closing instruction value. Then, the fuel injection volume instruction values are set to an output stage. Subsequently, at the next step S11, the fuel injection valve instruction pulses representing the fuel injection volume instruction values become the electromagnetic valve of the fuel injection valve 5 for the k-th cylinder for driving the fuel injection valve 5 of the kth cylinder. Then control is returned to the call routine.

According to the first embodiment, it is possible to reduce a difference in the fuel injection volume between the fuel injection in an overlapping cylinder and the fuel injected into a non-overlapping cylinder. In other words, the outputs of the cylinders are set to the same size. As a result, the vibrations of the internal combustion engine and the emissions can be suppressed.

Two or more first base Tqa Q-PC maps and two or more second base Tqb Q-PC maps may be provided. For example, it is possible to provide a plurality of first base Tqa Q-PC maps and / or a plurality of second base Tqb Q-PC maps for different sizes of overlaps between the fuel injection duration and the pumping duration.

The following description explains a variety of other embodiments that are applied to the present invention. These are directed to differences of the other embodiments of the first embodiment. In the following description, structural elements that are similar or the same as their corresponding parts used in the first embodiment will be denoted by the same reference numerals as the corresponding parts, but their explanations will not be repeated.

Second Embodiment

In the case of the second embodiment, only one basic map is used. The basic map is used to find the basic fuel injection duration Tqa for a non-overlapping cylinder. The first basic fuel injection duration Tqa is corrected according to an actual overlap time segment t for finding a second basic fuel injection duration Tqb for an overlapping cylinder.

More specifically, a correction means for correcting the first basic fuel injection duration Tqa for a non-overlapping cylinder for changing the difference of the first basic fuel injection duration Tqa from the second basic fuel injection period Tqb for an overlapping cylinder or for correcting the second basic fuel injection period Tqb for changing the difference of the second basic fuel injection period Tqb from the first basic fuel injection duration Tqa is used to make the second basic fuel injection duration Tqb shorter than the first basic fuel injection duration Tqa. Further, the correcting means corrects the first basic fuel injection duration Tqa for changing the difference of the first basic fuel injection duration Tqa from the second basic fuel injection duration Tqb or corrects the second basic fuel injection duration Tqb for changing the difference of the second basic fuel injection duration Tqb from the first basic fuel injection duration Tqa by using a correction amount ΔTq.

For example, a second basic fuel injection duration Tqb is set on the basis of a first basic fuel injection duration Tqa and a correction amount ΔTq. The correction amount ΔTq is set by a setting device. The setting means may provide a correction amount for a non-overlapping cylinder and another correction amount for an overlapping cylinder. The setting means may provide a correction amount ΔTq according to an overlap time segment t between a pumping duration and a fuel injection duration. For example, the setting means provides a correction amount ΔTq according to an overlap time segment t and a common line fuel pressure Pc. The overlap time segment t may be indicated by a detector. The actual overlap time segment t is given on the basis of an actual pump duration (= PSTART-PEND) and an actual volume injection time Tq. The actual pumping duration (= PSTART-PEND) can be detected by monitoring typical variations in common rail fuel pressure Pc.

For example, a pump duration start timing PSTART and a pump duration end timing PEND are detected from a fuel pressure Pc of the common rail. The pump duration start timing PSTART is also referred to as a pump duration start phase. On the other hand, the pump duration end timing PEND is also referred to as a pump duration end phase. An actual volume injection period Tq is replaced by a replacement which is an expected value. For example, a value near an actual volume injection duration Tq may be found from a final fuel injection timing TFIN and a first base fuel injection duration Tqa. Thus, the detection means detects an overlap time segment t based on a pump duration start timing PSTART, a pump duration end timing PEND, a final fuel injection timing TFIN, and a first base fuel injection duration Tqa.

The 5 . 6 and 7 show a method adopted by the second embodiment for controlling the fuel injection. In the case of the second embodiment, the step S9 of the flowchart shown in FIG 4 is shown by the steps S12, S13 and S14 of an in 5 replaced flowchart shown replaced. In addition, the new steps S21 to S24 of a flowchart shown in FIG 6 is shown. When the cylinder to be injected with the fuel is an overlapping cylinder, the flow of the control proceeds from the step S7 to the step S12. At step S12, a first base fuel injection duration Tqa found by using the first base map shown in FIG 2 is shown.

Then, at the next step S13, a correction amount ΔTq of the fuel injection volume is found after executing a process represented by the flowchart shown in FIG 6 is shown. A correction amount ΔTq of the fuel injection volume is found by using a map which is shown in FIG 7 is shown. More specifically, a correction amount ΔTq of the fuel injection volume is found from an overlap time segment t and a common rail fuel pressure Pc. This in 7 The map shown was set in advance by results of a number of experiments. A correction amount ΔTq is set as a value that reduces a difference of the fuel injection volume between the fuel injected into an overlapping cylinder and the fuel injected into a non-overlapping cylinder. Subsequently, at the next step S14, the correction amount ΔTq is subtracted from the first basic fuel injection duration Tqa to find the second base fuel injection period Tqb for an overlapping cylinder. In step S13, the value determined by the in 6 shown diagram executed to find an overlap time segment t.

The ECU 10 detects a pump duration start timing PSTART and a pump duration end timing PEND by monitoring a common rail fuel pressure Pc. It is possible to find a pump duration start timing PSTART and a pump duration end timing PEND by analyzing the waveform of the common rail fuel pressure Pc. A pump duration start timing PSTART and a pump duration end time adjustment PEND can also be found by using an electric circuit for detecting a predetermined waveform. It is also possible to set a pump duration start timing PSTART and a pump duration end timing PEND by using the ECU 10 to run software to execute a process.

This in 6 The flowchart shown begins with step S21 for inputting a pumping duration start timing PSTART and a pumping duration ending timing PEND closest to a standard fuel injection timing of the one in step S6 of FIG 5 shown flowchart identified k-th cylinder lie. This pump duration start timing PSTART and pump duration end timing PEND are a pump duration start timing PSTART and a pump duration end timing PEND set by the ECU 10 were detected in the immediately preceding cycle of the kth cylinder. The process performed at step S21 corresponds to a means for finding a pump duration start phase and a means for finding a pump duration end phase. The pumping duration start timing PSTART and the pumping duration ending timing PEND are each shown as a rotational phase. The pumping duration start timing PSTART is a timing at which the discharge valve of the fuel supply pump 3 is opened. The pumping duration start timing PSTART is a timing at which the rising gradient of the common rail fuel pressure Pc reaches a predetermined value. The pump duration start timing PSTART typically corresponds to a position close to a crank angle of 78 ° BTDC (before top dead center) of the second or third cylinder. On the other hand, the pump duration end timing PEND is a timing at which the plunger of the fuel supply pump 3 reaches a top dead center (a maximum lift amount position). The pump duration end timing PEND is a timing at which the rise gradient of the common rail fuel pressure Pc returns to the predetermined value after exceeding the predetermined value once. The pump duration end timing PEND typically corresponds to a position close to a crank angle of 48 ° ATDC (after top dead center) of the second or third cylinder.

At the next step S22, the first basic fuel injection duration Tqa, which is determined at step S12 of FIG 5 found flowchart is entered. Subsequently, at the next step S23, the completion fuel injection timing TFIN is input. Then, at the next step S24, an overlapping time segment t is found. The actual pumping duration of the fuel supply pump 3 is a difference between the pump duration start timing PSTART and the pump duration end timing PEND (PEND-PSTART). An experimental actual pumping duration is expressed by the final fuel injection timing TFIN and the first basic fuel injection duration Tqa. At step S24, an overlap time segment t is found from the actual pump duration and the experimental actual pump duration. The process performed at step S24 corresponds to a means for finding an overlapping time segment t. The process performed at step S24 includes a process performed by means for finding an actual pumping duration.

According to the second embodiment, a second basic fuel injection duration Tqb can be found for different overlap time segments, thereby making it possible to carry out the control of the fuel injection volume with high accuracy.

(Third Embodiment)

The 8th to 12 show a third embodiment, wherein 8th FIG. 10 is a flowchart illustrating a method of controlling fuel injection by the fuel injection valve. FIG. On the other hand shows 9 a flow chart illustrating a method for finding an overlap time segment. Routines that go through in the 8th and 9 are shown repeatedly executed at predetermined timings after the ignition switch is turned on.

This in 8th The flowchart shown begins with step S31 where engine parameters are input. The engine parameters include the engine speed NE and the accelerator opening ACCP. Then, at the next step S32, a target fuel injection volume Q from the engine speed NE and the accelerator opening ACCP is found. Subsequently, at the next step S33, a target fuel injection timing T from the engine speed NE and the accelerator opening ACCP is found. Then, at the next step S34, a common rail fuel pressure Pc is input.

Subsequently, at the next step S35, the target fuel injection timing T is converted into a basic fuel injection timing TBASE. Then, a basic fuel injection duration TqBASE is found from the common rail fuel pressure Pc and the base fuel injection timing TBASE. Subsequently, at the next step S36, the basic fuel injection timing TBASE and the basic fuel injection duration TqBASE are corrected. The corrected base fuel injection timing TBASE and the corrected basic fuel injection duration TqBASE are referred to as Tcom and Tqcom, respectively.

Then at the next step S37, an overlapping time segment t is found. A correction amount ΔTq is then found by using a map representing relations between the correction amount ΔTq, the overlap time segment t, and the common rail fuel pressure Pc, as in FIG 12 is shown. 9 FIG. 12 is a flowchart showing a detailed procedure for finding the overlap time segment t and the common line fuel pressure Pc. Subsequently, at the next step S38, the correction amount ΔTq is subtracted from the corrected basic fuel injection duration Tqcom to reach the final fuel injection duration TqFINAL.

Then, at the next step S39, the corrected base fuel injection timing Tcom is converted into a completion base fuel injection timing TFINAL. The final fuel injection duration TqFINAL and the completion base fuel injection timing TFINAL are then converted into fuel injection volume instruction values, specifically, a valve opening instruction value and a valve closing instruction value. Then, the fuel injection volume instruction values are set at an output stage. Subsequently, at the next step S40, fuel injection valve fuel injection instruction pulses representing the fuel injection volume instruction values become the electromagnetic valve of the fuel injection valve 5 for the k-th cylinder for driving the fuel injection valve 5 of the kth cylinder. Then control is returned to the call routine.

This in 9 The flowchart shown begins with step S41, in which a drive signal for the SCV 4 the fuel supply pump 3 is entered. Then, at the next step S42, a pump discharge volume Qp is established by using an in-pump discharge volume Qp 10 found map found. The map represents relationships between the engine speed NE, the SCV drive signal, and the pump discharge volume Qp, which are typically found in advance from results of experiments. In other words, the pump discharge volume Qp is found from an engine speed NE and an SCV drive signal.

Subsequently, at the next step S43, a pumping duration Pd from the pump discharge volume Qp and a crank angle is found. As in 11 2, pumping period Pd and pump discharge volume Qp have a fixed relationship. Then, at the next step S44, a basic fuel injection duration Tcom, a base fuel injection timing Tqcom, a fuel injection start delay time TDM and a fuel injection end delay time TDEM are input. The process performed at step S44 thus has operations represented by a Fuel injection start delay time calculating means and a fuel injection end delay time calculating means.

It should be noted that, as in 11 2, the fuel injection start delay time TDM is a time period that elapses since start of operation for lifting a nozzle needle after the fuel injection timing until the actual injection of fuel is achieved. The fuel injector 5 has a structure for opening its solenoid valve by lifting the nozzle needle in response to a common rail fuel pressure Pc. Thus, the fuel injection start delay time TDM varies according to the common rail fuel pressure Pc. For this reason, it is recommended to form a map by finding a relationship between the fuel injection start delay time TDM and the common rail fuel pressure Pc in advance, typically from results of experiments.

On the other hand, the fuel injection end delay time TDEM is a period of time that elapses since an operation for shutting off the flow supplied to the electromagnetic valve of the fuel injection valve 5 flows until an actual end of injection of the fuel is as in 10 is shown. In this case, it is best to make a map by finding a relationship between the fuel injection end delay time TDEM and the common rail fuel pressure Pc typically from results of experiments.

Subsequently, at the next step S45, a fuel injection start timing calculating means finds a fuel injection start timing T1 of the fuel injection valve 5 from the fuel injection start delay time TDM and the basic fuel injection duration Tcom. Then, a fuel injection end timing calculating means finds a fuel injection end timing T2 of the fuel injection valve 5 from the fuel injection end delay time TDEM, the basic fuel injection duration Tcom, and the base fuel injection timing Tqcom. Subsequently, an actual fuel injection duration calculating means finds an actual fuel injection duration ATq from the fuel injection start timing T1 and the fuel injection end timing T2. Then, in the next step S46, an overlap time segment calculator finds an overlap time segment t of the pumping duration Pd and the actual fuel injection duration ATq. Subsequently, at the next step S47, a fuel injection duration amount calculating means obtains a correction amount ΔTq by using a map which is formed in advance typically from results of experiments. As in 12 11, the map represents a relationship between the common rail fuel pressure Pc, the overlap time segment t, and the correction amount ΔTq.

In the case of a synchronous injection, such as one injection per pump operation or two injections per two pump operations, it is very likely that the fuel injection duration will randomly overlap the pumping duration depending on the pump duration end phase or not. On the other hand, in the case of asynchronous injection, such as two injections per pumping operation or six injections per four pumping operations, some cylinders are intended to be overlapping cylinders while other cylinders are intended to be non-overlapping cylinders.

According to the third embodiment, it is possible to make a difference in the fuel volume between a case where the fuel injection duration of a fuel injection valve overlaps the pumping duration of a fuel supply pump in a cylinder and a case in which the fuel injection duration of one fuel injection valve does not equal the pumping duration of the fuel supply pump to the same cylinder overlaps, suppress. As a result, it is possible to suppress a difference in the fuel injection volume between an overlapping case and a non-overlapping case of a cylinder that is in the internal combustion engine 1 is used, wherein the pumping duration of the fuel supply pump 3 different from the service life of the cylinder. In addition, it is possible to suppress a difference in the fuel injection volume between an overlapping cylinder and a non-overlapping cylinder.

(Fourth Embodiment)

In the case of the fourth embodiment, the ECU performs 10 an operation for detecting a pump duration start timing PSTART and a pump duration end timing PEND in addition to the operations performed by the second embodiment.

The ECU 10 has a low pass filter 10a and a high pass filter 10b used to perform a filtering operation of a signal received from the fuel pressure detection sensor 35 of the common line is received. The low pass filter 10a detects a slow change of the common rail fuel pressure Pc. An output value of the low-pass filter 10a represents an average fuel pressure Pc of the common rail. The low-pass filter 10a outputs a stable signal that is used to control the SCV 4 is used. The output value through the low-pass filter 10a is the average of the fuel pressure Pc of the common rail over a period between the end of a pumping stroke of the fuel supply pump 3 and the next injection. On the other hand, the high-pass filter detects 10b a rapid change of the common rail fuel pressure Pc. The output value through the high-pass filter 10b represents a common-rail instantaneous fuel pressure Pc. The high-pass filter 10b outputs a signal used to detect a pump duration start timing PSTART and a pump duration end timing PEND. A pump duration start timing PSTART and a pump duration end timing PEND are detected based on a change of the common rail fuel pressure Pc with a relatively large gradient. The low pass filter 10a and the high pass filter 10b reduce the load of a software operation by the ECU 10 is performed, thus increasing the processing speed.

13 FIG. 12 is a flowchart illustrating a detection process performed by the fourth embodiment to detect a pump duration start timing PSTART and a pump duration end timing PEND. In the case of the fourth embodiment, the operation of the second embodiment is performed on the basis of the pumping duration start timing PSTART and the pumping duration ending timing PEND, which are detected in the process indicated by the in 13 shown flowchart is shown.

After the ignition switch is turned on, one through the in 13 The routine shown in FIG. 10 has been executed with a predetermined timing, such as a timing in the range of 0.5 ms to 1.0 ms or 6 ° crank angle.

This in 13 The flowchart shown begins with step S131, in which a delivery of the high-pass filter 106 as the actual fuel pressure Pci of the common line is input. Then, an immediately preceding fuel pressure Pci1 of the common line is read from the memory. The immediately preceding common rail fuel pressure Pci1 was input to and stored in the memory at a previous time before the present time by a predetermined time period or a predetermined crank angle before the current crank angle by a predetermined difference of the crank angle. Subsequently, the flow of the routine goes to step S132 to find a deviation ΔPc of the common rail common rail pressure Pci from the immediately preceding common rail fuel pressure Pci1. Then, the routine proceeds to step S133 to determine whether or not the deviation ΔPc is greater than or equal to a first predetermined value PR1. When the result of the determination is YES, the flow of the routine proceeds to step S134, where the present position is used as a pump duration start phase PSTART and stored in a memory. Then, the common rail actual fuel pressure Pci is stored in the memory as the immediately preceding common rail fuel pressure Pci1.

When the result determined at step S133 is NO, on the other hand, the flow of the routine proceeds to step S135 to determine whether or not the deviation ΔPc is greater than or equal to a second predetermined value PR2 but equal to or less than a third predetermined value PR3. It should be noted that the first predetermined value PR1, the second predetermined value PR2, and the third predetermined value PR3 satisfy the following relationship: PR1>PR3> PR2. When the result of the determination is NO, the common rail actual fuel pressure Pci is stored in the memory as the immediately preceding common line fuel pressure Pci1 in the memory. It is to be noted that the second predetermined value PR2 is a value for discriminating the deviations ΔPc from a voltage drop caused by an injection of fuel. On the other hand, the third predetermined value PR3 is a value for discriminating the deviation ΔPc from a voltage drop caused by a static leak of a fuel injection valve 5 is caused.

When the determination result obtained in step S135 is YES, on the other hand, the flow of the routine proceeds to step S136, where the actual phase is stored as a pump duration end phase PEND. Then, the common rail actual fuel pressure Pci is stored in the memory as an immediately preceding common line fuel pressure Pci1.

For obtaining a determination result of YES at step S135, it is possible to add a condition that the pump duration start timing PSTART already exists besides the existing condition should be recorded. Alternatively, to obtain a determination result of YES at step S135, it is also possible to add a condition that the common rail fuel pressure Pc should already have increased besides the existing condition.

According to the fourth embodiment, the pumping time can be found by executing software processing. An overlap time segment t can thus be obtained for a variable pumping duration. As a result, the fuel injection volume can be adjusted with high accuracy.

The overlapping segment finding methods adopted by the second and fourth embodiments may also be applied to an asynchronous type fuel supply pump. For example, an overlapping time segment t that can be found by adopting the method provided by the fourth embodiment may be used to find a correction amount ΔTq explained in the description of the third embodiment. In addition, it is possible to eliminate differences in the fuel injection volume between a case where the fuel injection duration of a fuel injection valve overlaps the pumping duration of a fuel supply pump in a cylinder and a case in which the fuel injection duration of one fuel injection valve does not overlap the pumping duration of the fuel supply pump in the same cylinder ,

(Fifth Embodiment)

The 14 to 20 show a fifth embodiment of the present invention. One through the in 14 The illustrated routine is repeatedly executed at predetermined timings after the ignition switch is turned on.

The flowchart starts with step S141 in which a fuel pressure Pc of the common line is input. Then, at the next step S142, the routine represented by the in 13 is shown in order to detect a pump duration start phase PSTART and a pump duration end phase PEND and store them in the memory. Subsequently, at the next step S143, a pumping volume Qp over a period of 360 ° crank angle becomes the pump duration start phase PSTART, the pump duration end phase PEND, a cam profile (or plunger positions) of the fuel supply pump 3 and a crank angle. As in 15 2, a pumping volume Qp can be found geometrically from the cam profile, which can be approximated by a sinusoid.

Then, at the next step S144, a static basic leakage amount QSLBASE of the fuel injection valve is found by using an equation or map generated in advance from results of experiments to establish relations between the common rail pressure Pc, the engine speed NE, and the base static discharge amount QSLBASE represent the fuel injection valve, as in 16 is shown.

Subsequently, a fuel temperature correction coefficient f¿ is found by using a formula or a map generated in advance from results of experiments to represent relationships between the fuel temperature THF and the fuel temperature correction coefficient f¿, as in FIG 17 is shown. Finally, the static basic discharge amount QSLBASE of the fuel injection valve is multiplied by the fuel temperature correction coefficient f¿ to produce a static discharge amount QLS.

Subsequently, at the next step S145, a dynamic leak amount QDL of the fuel injection valve is found by using a formula or map generated in advance from results of experiments to determine relationships between the target fuel injection duration Tq, the common rail fuel pressure Pc and the dynamic coasting amount QDL represent the fuel injection valve, as in 18 is shown. Then, at the next step S146, the target fuel injection volume Q is converted into a fuel injection volume QINJ, which is then stored in the memory.

Subsequently, at the next step S147, a variation ΔP of the common rail fuel pressure Pc occurring over a period of 360 ° crank angle is found, as in the timing charts of FIG 19 is shown. More specifically, the common line fuel pressure Pc is monitored to find the variation ΔP. For example, the common rail fuel pressure Pc is periodically stored. Then, a deviation ΔP from the common rail common rail pressure Pcn becomes from a previous fuel pressure Pcn 360 the common line is calculated.

wobei das Symbol E ein Elastizitätsmodul für Druck bedeutet. Then, at the next step S148, a fuel volume increase ΔV of a high-pressure portion of the fuel injection system, which is a fuel volume increase required to increase the fuel pressure by a pressure increase ΔP, is calculated by using an equation given below or a map that results in advance from results of experiments was generated. $$\mathrm{\Delta }\text{V}=\left(\text{V / E}\right)\times \mathrm{\Delta }\text{P}$$

where the symbol E denotes a modulus of elasticity for pressure.

Subsequently, in the next step S149, a fuel spill amount calculating means calculates a fuel spill amount QLEAK in a period of 360 ° crank angle by using an equation given below and an in 20 shown fuel consumption distribution. $$\text{QLEAK}=\text{qp}-\left(\text{QSL}\times 4\right)-\left(\text{QDL}\times 2\right)-\left(\text{QINJ}\times 2\right)-\mathrm{\Delta }\text{v}$$

The above equation is an equation for a four-cylinder internal combustion engine with two injections per pump operation and with two injections per 360 ° crank angle.

Then, the flow of the routine proceeds to step S150 to determine whether or not the fuel spill amount QLEAK is greater than a predetermined value QL1. If the result of the determination is NO, the processing flow exits the routine indicated by the in 14 illustrated flowchart is shown. On the other hand, when the determination result obtained at step S150 is YES, it is determined that there is a leak of fuel in the high pressure fuel passage. In this case, the routine goes to step S151 in which various kinds of processings are performed. With respect to the processing, it is desirable to execute a fuel injection control or a pump control to maintain minimum operating conditions or to stop the engine.

As described above, a fuel leakage amount QLEAK can be found with high accuracy from PSTART and PEND found by performing the processing indicated by the in 13 shown flowchart is shown. In the event of an abnormality or malfunction of the fuel supply pump 3 in the event of an opening abnormality of the injection valve 5 and in the event of abnormality or malfunction of the fuel distribution system, it is possible to execute the fuel injection control or the pump control so as to maintain minimum operating conditions or stop the engine.

(Sixth Embodiment)

21 FIG. 10 is a block diagram illustrating an engine control unit. FIG 10 1, which is implemented by a sixth embodiment. The ECU 10 has a detection device 61 for detecting an actual pump duration end phase PEND. The detection device 61 detects an actual pump duration end phase PEND by performing the processing indicated by the in 13 shown flowchart is shown. The ECU also has a base pumping end phase storage device 62 for storing a base pump end phase. The base pumping end phase storage device 62 is typically an EEPROM or a RAM. A base pump end phase is determined based on an ideal module condition assumed with respect to the design of the internal combustion engine system. A base pump final phase may also be empirical with the assembly state of the fuel supply pump 3 and the internal combustion engine 1 be found that are set to an ideal state. For example, the common rail fuel pressure Pc varies in an ideal state, such as a waveform Pc0 of FIG 22 shown. 22 shows a base value PRR of the waveform Pc0. In addition, the ECU has 10 also a phase difference calculator 63 , The phase difference calculator 63 finds a difference DC between the actual pump duration end phase PEND and the base value PRR. The difference CC becomes the engine control device 64 for controlling the internal combustion engine according to the difference CC supplied. For example, the control of the fuel injection volume or the pump control is corrected according to the difference CC. The difference CC represents a failure of the fuel supply pump assembly 3 and the internal combustion engine 1 When the phase of the camshaft of the fuel supply pump 3 that is a phase relative to the rotational position of the crankshaft 15 is shifted from the normal phase, for example, increases the difference CC. When such an error exists, the common rail fuel pressure Pc typically changes as by a waveform Pc1 or Pc2 of 22 is shown. In this case, the phase difference calculator generates 63 a phase difference C1 or C2.

As described above, in the case of the sixth embodiment, an assembly error of the fuel supply pump 3 be recorded. In addition, it is possible to execute an engine control according to the assembly error.

(Modified versions)

As a substitute for structural elements of the embodiments described above, the following structural elements can be used. For example, as a substitute for the common rail fuel pressure Pc, it is possible to control the pressure of the fuel supply pump 3 discharged fuel to use. The pressure of the fuel expelled by the fuel supply pump 3 may be detected by using a fuel pressure sensor located at a fuel path between the fuel supply pump 2 and the fuel injection valves 5 is installed.

In addition, a signal for driving the electromagnetic valve of a fuel injection valve 5 be set with several levels. For example, the ECU 10 set a control scheme in which a first current to a fuel injection valve 5 during a first period, that is from an operation for starting the solenoid valve of the fuel injection valve 5 starts, is directed, and whereupon a second current to the fuel injection valve 5 is directed during a second period, which ends by the operation for closing the solenoid valve. In this case, a correction according to the overlap time segment t may be applied to the first or the second period (the first or the second period) or both periods (periods). For example, in the case of a long overlap time segment t, the first or the second period is shortened.

As a substitute for the calculation methods adopted in the embodiments, it is possible to adopt an implementation in which a pumping volume Qp from an engine speed NE, an opening of the inlet adjusting valve 4 (or the so-called SCV line current) and a fuel pressure Pc of the common line is found. It is also possible to provide an implementation in which a fuel leakage amount QL is found from an engine speed NE, a target fuel injection volume Q, a common rail fuel pressure Pc, and a fuel temperature THF. In addition, it is also possible to provide an implementation in which a fuel discharge amount QL is found from a pumping volume Qp, a target fuel injection volume Q and a fuel discharge amount QL.

Further, as a substitute for the operations performed in the embodiments, the following operations may be performed. An operation may be performed to adjust a pumping volume Qp from a cam profile (cam phases or plunger positions) of the fuel supply pump 3 , a pump duration start phase PSTART and a pump duration end phase PEND to calculate. In addition, an operation may be performed to determine an actual pumping duration from a pumping volume Qp and a cam profile of the fuel supply pump 3 to calculate geometrically. In addition, an operation may be performed to determine an actual fuel injection timing of a fuel injection valve 5 from a target fuel injection duration Tq, a target fuel injection timing T, a fuel injection start delay time, and a fuel injection end delay time, geometrically. Further, an operation may be performed to geometrically calculate an actual overlap time segment from an actual pump duration and an actual fuel injection duration. In addition, as a pump duration end phase, information regarding a geometric position on the engine assembly of the fuel supply pump may be provided 3 stored in a memory for later removal when necessary.

Although the overlap time segment is arranged by a period of time in the above-described embodiments, the overlap time segment may be measured and displayed by a crank angle or a cam angle instead.

The fuel supply pump 3 pressurizes the fuel with pressure from each cylinder of an internal combustion engine 1 through a fuel injector 5 for each cylinder is supplied.

An internal combustion engine control unit 10 sets a signal to drive the fuel injection valve 5 to a difference of a fuel injection volume between a case where a pumping duration of the fuel supply pump 3 a fuel injection duration of the fuel injection valve 5 overlaps for the cylinder, and a case in which a pumping duration of the fuel supply pump 3 a fuel injection duration of the fuel injection valve 5 for the same cylinder does not overlap, suppress. For the first case, an overlap time segment is defined as a period in which the pumping duration overlaps the fuel injection duration. When the overlap time segment is variable, the engine control unit continues 10 the signal for driving the fuel injection valve 5 according to the overlap time segment.

Claims (17)

A collector injection system used in an internal combustion engine (1), the collector injection system comprising: a collector (2) for pressurizing and storing high-pressure fuel at a pressure for injecting the fuel; a fuel supply pump (3) driven by the internal combustion engine (1) to apply a pressure for pumping the consumed fuel into the accumulator (2); a fuel injection valve (5) provided for each cylinder of the internal combustion engine (1) and for supplying high-pressure fuel stored in the accumulator (2) to the cylinder by injection of the high-pressure fuel into the cylinder; a fuel pressure detecting means for detecting a pressure of the fuel discharged by the fuel supply pump (3); an overlap time segment calculator for calculating an overlap time segment during which a pump duration of the fuel supply pump (3) overlaps a fuel injection period of the fuel injection valve; a first fuel injection duration determining means for determining a fuel injection duration of the cylinder of the internal combustion engine for which the pumping duration of the fuel supply pump (3) does not overlap the fuel injection period of the fuel injection valve (5), a target fuel injection volume set according to an operating condition of the internal combustion engine (1), and a second fuel injection duration Fuel pressure detected by the fuel pressure detecting means; and second fuel injection duration determination means for determining a fuel injection duration of the cylinder of the internal combustion engine for which the pumping duration overlaps the fuel injection period from the target fuel injection volume, the detected fuel pressure, and the overlap time segment the first fuel injection duration determination means finds a first fuel injection duration by using a basic map defined by the target fuel injection volume and the detected fuel pressure; and the second fuel injection duration determination means finds a second fuel injection duration by correcting the first fuel injection duration found by the first fuel injection duration determination means according to the overlap time segment. A collector injection system used in an internal combustion engine (1), the collector injection system comprising: a collector (2) for pressurizing and storing high-pressure fuel at a pressure for injecting the fuel; a fuel supply pump (3) driven by the internal combustion engine (1) to apply a pressure to the intake fuel and to pump the consumed fuel into the accumulator (2); a fuel injection valve (5) provided for each cylinder of the internal combustion engine (1) and for supplying high-pressure fuel stored in the accumulator (2) to the cylinder by injection of the high-pressure fuel into the cylinder; a fuel pressure detecting means for detecting a pressure of the fuel discharged by the fuel supply pump (3); fuel injection duration determination means for determining a fuel injection duration from a target fuel injection volume set in accordance with an operating condition of the internal combustion engine (1) and a fuel pressure detected by the fuel pressure detection means; an overlap time segment calculator for calculating an overlap time segment during which a pump duration of the fuel supply pump (3) overlaps a fuel injection period of the fuel injection valve; and a fuel injection duration correcting means for correcting the fuel injection duration according to the overlap time segment, the overlapping time segment calculating means comprising: pump duration start phase calculating means for finding a pump duration start phase from the detected fuel pressure; pump duration end phase calculation means for finding a pump duration end phase from the detected fuel pressure; and an actual pump duration calculation means for finding an actual pump duration from the pump duration start phase and the pump duration end phase, and wherein an overlap time segment is found from the actual pump duration, the fuel injection duration, and a fuel injection timing set in accordance with an operation state of the internal combustion engine. Collector injection system according to Claim 2 wherein the fuel injection duration correction means comprises correction quantity calculating means for calculating a fuel injection duration correction amount from the overlapping time segment; and wherein the fuel injection duration is corrected based on the fuel injection duration correction amount. Collector injection system according to Claim 2 or 3 wherein the overlap time segment calculating means has a pump duration calculation means for calculating a pump duration from a discharge volume of the fuel supply pump (3); and the overlap time segment calculator calculates an overlap time segment from the pump duration and the fuel injection duration. Collector injection system according to one of Claims 2 to 4 wherein the overlapping time segment calculating means comprises: fuel injection start timing calculating means for calculating a fuel injection start timing; fuel injection end timing calculating means for calculating a fuel injection end timing; actual fuel injection duration calculating means for calculating an actual fuel injection duration from the fuel injection start timing and the fuel injection end timing; and a pump duration calculator for calculating a pump duration, and wherein the overlap time segment calculator calculates an overlap time segment from the actual fuel injection duration and the pump duration. Collector injection system according to one of Claims 1 to 4 wherein the overlap time segment calculating means comprises: fuel injection duration calculating means for calculating a fuel injection instruction pulse duration from the detected fuel pressure and the target fuel injection volume; fuel injection start delay time calculating means for calculating a start delay time from a time point when a fuel injection instruction pulse is started at a time when fuel injection is actually started; a fuel injection end delay time calculating means for calculating a final delay time from a time point when a fuel injection command pulse is stopped to a time when fuel injection is actually stopped, pump duration start phase calculating means for finding a pump duration start phase from the detected fuel pressure, and a pump duration end phase calculating means for Finding a pump duration end phase from the detected fuel pressure, and wherein the overlap time segment calculator calculates the overlap time segment from an actual fuel injection timing calculated from a fuel injection timing set according to an operating condition of the engine and the start delay time, an actual fuel injection instruction pulse duration resulting from the fuel injection instruction pulse duration, the start delay time and the end delay time, the pump duration start phase, and the pump duration end phase are calculated. A collector injection system used in an internal combustion engine, the collector injection system comprising: a collector (2) for pressurizing and storing high-pressure fuel at a pressure for injecting the fuel; a fuel supply pump (3) having a cam driven by the internal combustion engine (1) and a plunger driven by the cam to slide back and forth in a pump cylinder, causing a pressure to be applied absorbed fuel is applied and the absorbed fuel is pumped into the collector (2); a fuel injection valve provided for each cylinder of the internal combustion engine and for supplying high-pressure fuel collected in the accumulator to the cylinder by injection of the high-pressure fuel into the cylinder; fuel pressure detecting means for detecting a fuel pressure of fuel discharged by the fuel supply pump (3); pump duration start phase detecting means for detecting a phase of the phase of the fuel supply pump (3) as a pump duration start phase when a change of the fuel pressure detected by the fuel pressure detection means becomes equal to or exceeds a predetermined level; a pumping end phase detecting means for detecting a cam phase of the fuel supply pump (3) as a pumping end end phase when a change in the fuel pressure detected by the fuel pressure detecting means becomes equal to or lower than the predetermined level after the change exceeds the predetermined level or for storing Pump end phase, which is determined geometrically from an assembly relationship between the fuel supply pump (3) and the internal combustion engine (1); and engine control means for controlling the pump duration start phase and the pump duration end phase in the control of the internal combustion engine (1). Collector injection system according to Claim 7 wherein a cam phase as the pump duration start phase is detected when a deviation of the current fuel pressure from a previous fuel pressure increases to a value equal to at least a predetermined value when the previous fuel pressure as a fuel pressure supplied by the fuel pressure detection means at a previous time is defined as being a fuel pressure detected by the fuel pressure detecting means at the present time, which lags the previous time by the predetermined time. Collector injection system according to Claim 8 wherein a cam phase is detected as the pump duration end phase when a deviation of a later fuel pressure from the current fuel pressure decreases to a value less than or equal to a predetermined value when the current fuel pressure is defined as a fuel pressure supplied by the fuel pressure detecting means the present time is detected by a predetermined period of time before a later time, and wherein the later fuel pressure is defined as a fuel pressure detected by the fuel pressure detecting means at the later time lags the present time by the predetermined time period. Collector injection system according to one of Claims 7 to 9 wherein the engine control means comprises: a fuel injection volume and fuel injection timing determining means for finding an instruction fuel injection volume and an instruction fuel injection timing according to an operation state of the internal combustion engine (1); fuel injection duration determination means for determining an instruction fuel injection duration from the fuel pressure and the command fuel injection volume; and an overlap time segment calculator for calculating an overlap time segment during which a pump duration of the fuel supply pump (3) overlaps a fuel injection duration of the fuel supply valve, the pump duration start phase, the pump duration end phase, the command fuel injection duration, and the command fuel injection timing. Collector injection system according to Claim 10 wherein the engine control means has fuel injection duration correction means for correcting the command fuel injection duration according to the overlap time segment; the fuel injection duration correction means has a correction amount calculating means for calculating a fuel injection duration correction amount from the fuel pressure and the overlap time segment; and wherein a corrected fuel injection duration is found from the command fuel injection duration and the fuel injection duration correction amount. Collector injection system according to one of Claims 7 to 9 wherein the engine control means includes pumping volume calculating means for calculating a pumping volume of the fuel pumped into the accumulator by the fuel supply pump from the cam profile, the cam positions or plunger positions, the pumping duration starting phase, and the pumping end phase. Collector injection system according to Claim 12 wherein the engine control means comprises: fuel injection volume determining means for determining an instruction fuel injection volume according to an operation state of the internal combustion engine (1); fuel injection duration determination means for determining an instruction fuel injection duration from the fuel pressure and the command fuel injection volume; a fuel temperature detecting means for detecting a fuel temperature; a static discharge amount calculating means for calculating a static discharge amount of the fuel injection valve from the fuel temperature and the fuel pressure; dynamic spill amount calculating means for calculating a dynamic spill amount of the fuel injection valve from the fuel pressure and the command fuel injection duration; and a fuel spill amount calculating means for calculating an amount of fuel leaking from a high-pressure piping based on the static spill amount of the fuel injection valve and the dynamic spill amount of the fuel injection valve. Collector injection system according to Claim 13 wherein the engine control means performs pump control or fuel injection volume control for improving safety when the amount of the fuel leaking from the high-pressure fuel piping increases or exceeds a predetermined value. Collector injection system according to one of Claims 7 to 14 wherein the fuel pressure detecting means is a fuel pressure detector for generating an electrical signal representative of a detected fuel pressure; an electronic control unit (10) including an embedded computer is provided which is adapted to include functions of the pump duration start phase detection means, the pump duration phase detection means and the engine control means; and wherein the electronic control unit (10) includes a low pass filter for passing only the electrical signal of the fuel pressure sensor with small variations to the computer and a high pass filter for passing only the electrical signal of the fuel pressure sensor with large variations to the computer. A collector injection system used in an internal combustion engine (1), the collector injection system comprising: a collector (2) for pressurizing and storing high-pressure fuel at a pressure for injecting the fuel; a fuel supply pump (3) having a cam that is driven by the internal combustion engine (1) and a plunger that is driven by the cam to reciprocate back and forth in a pump cylinder, wherein a pressure caused to be applied to received fuel, and wherein the absorbed fuel is to be pumped into the collector (2); a fuel injection valve (5) provided for each cylinder of the internal combustion engine (1) and for supplying the high-pressure fuel stored in the accumulator (2) to the cylinder by injection of the high-pressure fuel into the cylinder; fuel pressure detecting means for detecting a fuel pressure of the fuel discharged by the fuel supply pump (3); a pumping end phase detecting means for detecting a cam phase of the fuel supply pump (3) as a pumping end end phase when a change in the fuel pressure detected by the fuel pressure detecting means becomes lower than or equal to a predetermined level after the change exceeds the predetermined level; pump end phase storage means for storing the basic values of the pump duration end phase, each of which is found in advance from a relationship between a rotation angle of an output shaft of the internal combustion engine (1) and a cam phase of the fuel supply pump (3); a phase difference calculator for calculating a phase difference between a camshaft detected as a pump duration end phase and one of the base values corresponding to the pump duration end phase. Collector injection system according to Claim 1 or 2 wherein the overlap time segment is indicated by a time duration, a crank angle or a cam angle.

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