DE112011100766B4 - Control device for internal combustion engine - Google Patents

Abstract

A control device for an internal combustion engine (11), the control device comprising: an EGR device (50) for recirculating exhaust gas by returning part of the exhaust gas flowing in an exhaust pipe (19) of the internal combustion engine (11) into an intake pipe; Determining unit for determining a cetane number of fuel to be supplied to the internal combustion engine (11); anda control unit (40), wherein the control unit (40), if the cetane number determined by the determining unit, during an execution period which is a period immediately after the initiation of the start of the internal combustion engine (11) until the start of the manipulation of an accelerator actuating element, is low, can reduce an EGR amount by the EGR device (50) in an idling operation and adjusts the fuel injection period backward compared to other cases.

Description

TECHNICAL FIELD

The present invention relates to a control device for an internal combustion engine that determines a cetane number of fuel supplied to an internal combustion engine and performs engine operation control according to the determined cetane number.

TECHNICAL BACKGROUND

In a self-igniting internal combustion engine, fuel is ignited after a certain time has passed after fuel has been injected into a cylinder through a fuel injection valve (ignition delay). In order to improve the output performance and the emission performance of the internal combustion engine, a control and regulating device is widely used which regulates an execution mode of an engine control or regulation, for example the injection time or the start of injection and the injection quantity for a fuel injection, taking this ignition delay into account.

In an internal combustion engine, the longer the ignition delay, the lower the cetane number of the fuel used. Even if an execution mode of the engine control is set on delivery of the internal combustion engine on the assumption that fuel with a typical cetane number is used, an ignition timing of the fuel is retarded and the combustion state worsened when fuel with a relatively low cetane number, for example Winter fuel delivered to the fuel tank. In some cases, it can cause misfiring.

In order to counteract the occurrence of these shortcomings, it is desirable to correct the mode of execution of the engine control based on an actual cetane number of the fuel injected into the cylinder.

the JP 2007-285195 A proposes, for example, an internal combustion engine which has an exhaust gas recirculation device (EGR) for recirculating the exhaust gas by returning part of the exhaust gas flowing through an exhaust pipe of the internal combustion engine into an intake pipe, and in which a cetane number of the fuel that is to be supplied to the internal combustion engine , is estimated or provisionally determined and the amount of exhaust gas (an EGR amount) to be returned to the exhaust pipe by the EGR device is corrected depending on the thus estimated cetane number. In the device, the EGR amount is corrected so that it is decreased when the estimated cetane number decreases. As a result, it is possible to improve the state of combustion of the fuel, thereby preventing misfires from occurring.

From the US 2004/0149255 A1 An internal combustion engine and a method for operating an internal combustion engine in a plurality of engine modes and transferring operation between the plurality of modes is known. The method comprises the steps of: operating the engine in a mode of compression ignition of premix; Operating the engine in a homogeneous dual fuel mixture transition mode (HCDFT transition mode), wherein in the HCDFT transition mode, an amount of the second fuel early in the process forms a mixture too lean to spread a self-sustaining flame and an amount of the first fuel, which is larger than the amount of the second fuel is supplied later; and transferring or switching engine operation between the HCDFT transition mode and the premixed compression ignition mode.

SUMMARY OF THE INVENTION

Problems to be solved by the invention.

Usually, an EGR device has an EGR line, which causes an intake line and an exhaust line to communicate with one another in an internal combustion engine, and an EGR valve, which changes a flow cross-section of the EGR line. In the EGR device, an amount of EGR is regulated by an operation control of the EGR valve. In the EGR device, due to the volume of the EGR pipe, the volume of the portion from the connection part to the EGR pipe in the intake pipe of the internal combustion engine to the cylinder of the internal combustion engine, or the like, there may be a delay in a change in an EGR amount with respect to a change in a Opening degree of the EGR valve cannot be avoided. For this reason, the responsiveness or stability of a change in the amount of EGR with respect to a change in the degree of opening of the EGR valve is poor, and the EGR device can hardly finely control the amount of EGR. Therefore, a regulation error in the regulation of the amount of EGR by the EGR device is easy to occur.

In particular, in an idling operation immediately after an initiation of a start of the internal combustion engine, an operating state of the engine is very susceptible to a regulation error of the EGR amount because of the small absolute amount of the intake amount, and furthermore, the combustion state of the fuel is due to a low temperature in the cylinder of the Internal combustion engine tends to be unstable. For this reason, if the EGR amount is increased too much due to a regulation error at that time, there is a high possibility that the occurrence of misfire may not be properly suppressed. On the other hand, if the EGR amount is decreased too much due to a regulation error at this time, the combustion temperature of fuel in the cylinder rises, so that nitrogen oxide (NOx) in the exhaust gas increases accordingly.

Thus, it is an object of the present invention to provide a control device for an internal combustion engine capable of suppressing the occurrence of misfires when using fuel having a low cetane number and reducing the emission of nitrogen oxide.

Means of solving the problems

To achieve the object, and according to one aspect of the present invention, there is provided a control device for an internal combustion engine that includes an EGR device that performs exhaust gas recirculation by taking part of the exhaust gas flowing in an exhaust pipe of the internal combustion engine into a Returns the suction line. The control device estimates a cetane number of fuel to be supplied to the internal combustion engine. When the cetane number estimated by a determining unit is low during an execution period which is a period immediately after initiation of start of the internal combustion engine to start of manipulation of an accelerator operating member, an EGR amount is by in an idling operation the EGR device is decreased and a fuel injection start is retarded as compared with other cases.

When the idling operation is carried out immediately after initiation of the start of the internal combustion engine in a situation where the cetane number estimated by the determination section is low, that is, when a combustion state of the fuel is highly susceptible to an EGR amount regulation error, and the As a result, the combustion state of the fuel is likely to be unstable, it is possible to reduce the EGR amount regulation error in accordance with a decrease in the absolute amount of EGR. Therefore, the influence of the EGR amount regulation error on the combustion state of the fuel can be reduced. In addition, the start of fuel injection is shifted backwards in accordance with a decrease in the amount of EGR. As a result, the state of combustion of the fuel can be adjusted by adjusting the fuel injection start at which the state of combustion of the fuel in a cylinder of the internal combustion engine can be adjusted with greater accuracy compared to regulating the amount of EGR.

According to this device, it is thus possible to properly adjust the combustion state of the fuel in the cylinder of the internal combustion engine when using fuel with a low cetane number. As a result, the occurrence of misfire can be suppressed and the emission of nitrogen oxide (NOx) can be suppressed.

According to this device, it is also possible to reduce the amount of EGR and move the fuel injection start to the rear in order to adjust the combustion state with great accuracy only when the temperature in the cylinder of the internal combustion engine is immediately after initiation of the start Internal combustion engine is low, ie only for a certain period during which the combustion state of the fuel in the cylinder is likely to become unstable.

The control unit preferably sets the EGR amount to zero. According to this device, the influence of the EGR amount regulation error on the combustion state of the fuel can be eliminated. Therefore, the state of combustion of the fuel can be adjusted with greater accuracy.

According to one aspect of the present invention, the delay or adjustment of the start of fuel injection to the rear is carried out under the condition that an external pressure is equal to or higher than a predetermined decision pressure. When the external pressure is low, the density of the air is decreased, so the amount of oxygen contained in the intake air is small. For this reason, there is a tendency for the combustion state of the fuel in the cylinder of the internal combustion engine to deteriorate, causing misfires to occur. According to this device, when the external pressure is low and misfire is likely to occur, the fuel injection start delay is prevented, that is, a change that deteriorates the combustion state of the internal combustion engine is prevented. Therefore, the occurrence of misfire can be reliably suppressed. In addition, when the external pressure is high and misfires are comparatively rare, a change in which the fuel injection start is retarded is permitted. As a result, the emission of NOx can be suppressed.

Figure list

• 1 Fig. 3 is a schematic view showing the structure of a control device for an internal combustion engine according to an embodiment of the present invention;
• 2 Fig. 13 is a cross-sectional view showing a cross-sectional structure of the fuel injection valve;
• 3 Fig. 13 is a time chart showing a relationship between changes in fuel pressure and a waveform of fuel injection rate and a history of fuel injection in a detection period;
• 4th Fig. 13 is a flowchart showing a procedure in performing correction processing;
• 5 Fig. 13 is a timing chart showing an example of a relationship between a waveform in a detection period and a waveform in a basic period;
• 6th Fig. 13 is a flowchart showing a specific procedure in performing processing for acquiring a first index value;
• 7th Fig. 13 is a diagram explaining a method of calculating an amount of speed fluctuation;
• 8th Fig. 13 is a flowchart showing the procedure in executing an EGR control process;
• 9 Fig. 13 is a flowchart showing the procedure for performing a method for retarding an injection start; and
• 10 Fig. 13 is a timing chart showing an example of an execution mode for each process.

MODE FOR CARRYING OUT THE INVENTION

A control device for an internal combustion engine according to an embodiment of the present invention will be described below.

As in 1 shown is a vehicle 10 with an internal combustion engine 11 equipped, which serves as a drive source. A crankshaft 12th of the internal combustion engine 11 is via a clutch mechanism 13th and a manual transmission 14th with a wheel 15th connected. When a driver uses a clutch actuator (e.g. a clutch pedal) in the vehicle 10 operated, the clutch mechanism is operated 13th brought into an operating state in which the crankshaft 12th and the manual transmission 14th are separated from each other.

A suction line 17th is with cylinders 16 of the internal combustion engine 11 connected. Air gets through the suction line 17th in the cylinder 16 of the internal combustion engine 11 sucked. The number of cylinders 16 in the internal combustion engine 11 is four (No. 1 to No. 4). The internal combustion engine 11 has fuel injectors 20th on, which are direct ice injectors, each one of the cylinders 16 are equivalent to. The fuel produced by a valve-opening driving operation of the fuel injection valve 20th is injected when it comes into contact with the sucked in air in the individual cylinders 16 of the internal combustion engine 11 is compressed and heated, ignited and burned. In the internal combustion engine 11 is in each cylinder 16 a piston 18th pushed down by energy generated by the combustion of the fuel, causing the crankshaft 12th is made to rotate. The gas that is in the cylinders 16 of the internal combustion engine 11 is burned, becomes exhaust gas to an exhaust pipe 19th in the internal combustion engine 11 discharged.

An exhaust gas recirculation (EGR) device 50 that recirculates exhaust gas by removing some of the exhaust gas that is in the exhaust pipe 19th flows to the suction line 17th brings back is on the internal combustion engine 11 attached. The EGR device 50 has an EGR line 51 that causes the suction line 17th and the exhaust pipe 19th in the internal combustion engine 11 communicate with each other, and an EGR valve 52 on that on the EGR line 51 is attached and is used to create a flow cross-section of the EGR line 51 to regulate. In the EGR device 50 is the amount of exhaust gas (EGR gas) coming out of the exhaust pipe 19th is returned to the intake pipe, that is, an amount of EGR, by changing the opening degree of the EGR valve 52 regulated.

Any fuel injector 20th is via a branch line 31a with a common pressure line 34 connected, and the common pressure line 34 is via a feed line 31b with a fuel tank 32 connected. The supply line 31b is with a fuel pump 33 provided that promotes fuel under pressure. In the present embodiment, the fuel produced by the pressurized delivery by the fuel pump 33 has been compressed in the common pressure line 34 stored and in the individual fuel injection valves 20th delivered. There is also a return line 35 with the fuel injector 20th connected and to the fuel tank 32 connected. Part of the fuel in the fuel injector 20th is through the return line 35 in the fuel tank 32 brought back.

The internal structure of the fuel injector 20th is described below.

As in 2 shown is a needle valve 22nd in one housing 21 each fuel injector 20th intended. The needle valve 22nd is provided in a state in which a reciprocating movement (a movement in a vertical direction in 2 ) in the housing 21 can be carried out. In the case 21 there is a spring 24 who have favourited the needle valve 22nd constantly to an injection port 23 pushes towards (down in 2 ). A nozzle chamber 25th is in one place on one side of the needle valve 22nd (below in 2 ) in the housing 21 formed, and a pressure chamber 26th is on the other side (above in 2 ) educated.

The injection openings 23 that cause the inside of the chamber 25th with the outside of the case 21 can communicate are in the nozzle chamber 25th is formed, and fuel is supplied from the branch pipe 31a (the common pressure line 34 ) via an inlet line 27 delivered. The nozzle chamber 25th and the branch line 31a (the common pressure line 34 ) are via a connection or communication line 28 with the pressure chamber 26th connected. The pressure chamber 26th is also about a derivative 30th with the return line 35 (the fuel tank 32 ) connected.

The fuel injector 20th is an electrically controlled valve, and a piezoelectric actuator 29 is in the housing 21 intended. In the piezoelectric actuator 29 is a plurality of piezoelectric elements that expand and contract upon input of a driving signal, layered. A valve element 29a is on the piezoelectric actuator 29 attached and the valve element 29 is in the pressure chamber 26th intended. By moving the valve element 29a due to actuation of the piezoelectric actuator 29 becomes either the communication line 28 (the nozzle chamber 25th ) or the derivative 30th (the return line 35 ) brought about with the pressure chamber 26th to communicate.

If in the fuel injector 20th a signal to close the valve in the piezoelectric actuator 29 is input, the piezoelectric actuator pulls 29 together, making the valve element 29a is moved so that the communication line 28 with the pressure chamber 26th is connected and the return line 35 and the pressure chamber 26th separated from each other. Thus, communication of the nozzle chamber becomes 25th with the pressure chamber 26th effected in a state in which the discharge of the fuel in the pressure chamber 26th into the return line 35 (the fuel tank 32 ) is prevented. Because of this, the pressure difference between the nozzle chamber 25th and the pressure chamber 26th greatly reduced so that the needle valve 22nd by a biasing force of the spring 24 is moved to a position in which there is the injection openings 23 closes, and the injection valve 20th is thus brought into a state or a position (a valve-closed position) in which no fuel is injected.

If, however, a signal to open the valve in the piezoelectric actuator 29 is input, the piezoelectric actuator expands 29 off, causing the valve element 29a is moved so that it is the communication line 28 and the pressure chamber 26th separates from each other and the return line 35 with the pressure chamber 26th connects. Thus, in a state where the fuel flows out from the nozzle chamber 25th to the pressure chamber 26th is prevented some of the fuel in the pressure chamber 26th through the return line 35 in the fuel tank 32 returned. For this reason, the pressure of the fuel in the pressure chamber decreases 26th so that the pressure difference between the pressure chamber 26th and the nozzle chamber 25th gets bigger. Because of this pressure difference, the needle valve will 22nd against the pretensioning force of the spring 24 moved and thus from the injection port 23 solved. At the same time, the fuel injector 20th brought into a state or a position (an open valve position) in which fuel is injected.

A pressure sensor 41 is on the fuel injector 20th integrated attached. The pressure sensor 41 is used to output a signal that corresponds to a fuel pressure PQ in the inlet line 27 is equivalent to. In contrast to a device that detects fuel pressure at a point away from the fuel injector 20th is, for example, a fuel pressure in the common pressure line 34 (please refer 1 ), a fuel pressure may be at a portion near the injection port 23 of the fuel injection valve 20th are detected and a change in the fuel pressure in the fuel injection valve 20th due to an opening of the fuel injection valve 20th can be recorded more precisely. The pressure sensor 41 is for each fuel injector 20th provided, ie for each cylinder 16 of the internal combustion engine 11 .

As in 1 is shown, are various sensors for detecting the operating state as peripheral devices in the internal combustion engine 11 intended. As these sensors, there is, for example, a crank sensor 42 showing the phase of rotation and the speed of rotation of the crankshaft 12th (an engine speed NE), and an accelerator sensor 43 that detects an operation amount of an accelerator operation member (eg, an accelerator pedal) (an accelerator operation amount ACC), in addition to the pressure sensor 41 intended. An external pressure sensor is also provided 44 for detecting an air pressure outside the internal combustion engine 11 (the outside air pressure), a suction amount sensor 45 , the amount of air drawn in, the through the suction line 17th flows (a line suction amount GA) is detected, and a suction pressure sensor 46 showing the pressure (a suction pressure PM) in the suction pipe 17th recorded, provided. There is also an opening sensor 47 to detect an opening of the EGR valve 52 (an EGR opening degree VR), an operation switch 48 that occurs when starting the operation of the internal combustion engine 11 is turned ON and turned OFF upon termination of the operation, and the like.

As peripheral devices of the internal combustion engine 11 is also, for example, an electronic control and regulation unit 40 , which includes a microcomputer or the like, is provided. The electronic control and regulation unit 40 serves as a determination section and as a control section, retrieves output signals from various sensors, performs various calculations on the basis of the output signals and, depending on a calculation result, performs various controls or regulations with regard to the operation of the internal combustion engine 11 by, for example, operational control of the EGR valve 52 (an EGR control), a drive control of the fuel injection valve 20th (a fuel injection control) or the like.

The EGR control according to the present embodiment is basically performed in the following manner.

First, a determination or estimated value (a current EGR rate Regr) for the ratio of the EGR amount to the amount of gas that is in the cylinder 16 of the internal combustion engine 11 is calculated based on the engine speed NE, the line suction amount GA and the suction pressure PM. The current EGR rate can be determined based on the following considerations. It is possible to control the amount of gas that goes into the cylinder 16 of the internal combustion engine 11 is sucked (a gas containing fresh air and EGR gas) to determine based on the intake pressure PM and the engine speed NE. In addition, the amount of air (the amount of fresh air) that is released during one revolution of the crankshaft 12th in the cylinder 16 is sucked, can be determined based on the line suction amount GA and the engine speed NE. The amount (gas amount - fresh air amount) obtained by subtracting the fresh air amount from the gas amount can be obtained as the amount corresponding to the current EGR amount, and an EGR rate ((gas amount - fresh air amount) / gas amount) can be Can be determined based on the amount and the amount of gas described above.

In addition, a control target value for the EGR rate (a target EGR rate Tegr) is set based on the engine speed NE and a fuel injection amount (more specifically, a required injection amount TAU, which will be described later). Then, a control target value for an EGR opening degree VR (a target EGR opening degree Tyr) is set based on the target EGR rate Tegr.

An operational control of the EGR valve 52 is carried out on the basis of the target EGR opening degree Tvr, the target EGR rate Tegr and the current EGR rate Regr. More specifically, provisional control setting the target EGR opening degree Tvr as the provisional control amount and feedback control based on the difference between the target EGR rate Tegr and the current EGR rate are used as operation control of the EGR valve 52 carried out.

The fuel injection control according to the present embodiment is basically performed in the following manner.

First, a control target value (the required injection amount TAU) related to a fuel injection amount for the operation of the internal combustion engine is determined 11 is calculated based on the accelerator operation amount ACC, the engine speed NE, or the like. Then, a control target value for a fuel injection start (a required injection start Tst) and a control target value for a fuel injection duration (a required injection duration Ttm) are calculated based on the required injection amount TAU and the engine speed NE. The valve opening drive control for each fuel injector 20th is performed on the basis of the required start of injection Tst and the required injection duration Ttm. As a result, fuel is always supplied in an amount corresponding to an operating state of the internal combustion engine 11 corresponds to the individual fuel injectors 20th injected and then into each cylinder 16 of the internal combustion engine 11 delivered.

In the fuel injection control according to the present embodiment, if the engine speed NE is during a decrease in the running speed of the vehicle 10 and the engine speed NE reaches a predetermined speed range because the operation of the accelerator operating member has been discontinued (accelerator operation amount ACC = 0), control performed to effect the fuel injection for driving the internal combustion engine 11 temporarily terminate (thrust cut control).

In the fuel injection control of this embodiment, three regions are set, namely regions with low, medium and high cetane numbers of the fuel (a lower one Cetane number region, a middle cetane number region, and an upper cetane number region), and the fuel injection control is performed in a different execution mode for the different regions. For example, the required start of injection Tst is earlier in the region with a low cetane number. More specifically, for each of the three cetane number regions, a relationship between the engine operating state, which is determined on the basis of the required injection amount TAU and the engine speed NE, and the required injection start Tst, which corresponds to the cetane number region, is determined in advance on the basis of the results of various experiments and simulations, and the relationship is in the electronic control unit 40 stored in the form of computational maps (ML, MM, MH). On the basis of the injection quantity TAU required in each case and the engine speed NE, the required start of injection Tst in the lower, middle and upper cetane number regions is calculated from the computational maps ML, MM and MH.

When the fuel injection from the fuel injector 20th is carried out, it can in some cases because of initially existing individual differences, time-related changes in the fuel injection valve 20th or the like, there may be an error in the execution time or the injection amount. This error is disadvantageous because it affects the output torque of the internal combustion engine 11 changes. For this reason, in this embodiment, correction processing is performed in which a waveform of a fuel injection rate or a fuel injection history in a detection period is based on that from the pressure sensor 41 detected fuel pressure PQ is formed and a correction of the required start of injection Tst and the required injection duration Ttm are corrected on the basis of the waveform in the detection period to determine the fuel injection from the fuel injection valve 20th in a suitable manner depending on the operating state of the internal combustion engine 11 perform. The correction process will be for each cylinder 16 of the internal combustion engine 11 carried out separately.

The fuel pressure in the fuel injector 20th varies according to the opening / closing operations of the fuel injection valve 20th , for example, it decreases when the fuel injector 20th opens and increases when the fuel injector 20th is then closed. By monitoring the fluctuating waveform of the fuel pressure in the fuel injector 20th while the fuel injection is being carried out, the actual operating characteristics of the fuel injection valve 20th (For example, the actual fuel injection amount, the timing when a valve opening operation starts, the timing when a valve closing operation starts, and the like) can be recognized with great accuracy. By correcting the required start of injection Tst and the required injection duration Ttm on the basis of the current operating parameters of the fuel injection valve 20th Therefore, the start of fuel injection and the fuel injection quantity can be configured in a manner that corresponds to the operating state of the internal combustion engine 11 must be set exactly.

The correction process is described in detail below.

First, a procedure for establishing the fuel pressure fluctuation mode while performing fuel injection (in the present embodiment, a waveform of the fuel injection rate in the detection period) will be described.

3 Fig. 13 shows a relationship between changes in the fuel pressure PQ and the waveform of the fuel injection rate in the detection period.

As in 3 In the present embodiment, each time point at which the opening operation of the fuel injection valve 20th (more precisely an opening movement of the needle valve 22nd ) is started (a valve opening operation start Tos), a point of time at which the fuel injection rate reaches its maximum value (a point of time Toe at which a maximum injection rate is reached), a point of time when the fuel injection rate starts to decrease (an injection rate decrease start Tcs), and a time point at which the closing operation of the fuel injection valve 20th (more precisely a closing movement of the needle valve 22nd ) is completed (a valve closing operation end Tce) is detected.

First, an average value of the fuel pressure PQ for a predetermined time period T1 immediately before the start of the valve opening operation of the fuel injection valve is obtained 20th is calculated and the average value is stored as the reference pressure Pbs. The reference pressure Pbs is used as a pressure corresponding to the fuel pressure in the fuel injection valve 20th when closing the valve.

Then, a value obtained by subtracting a predetermined pressure P1 from the reference pressure Ps is calculated as the operating pressure Pac (Pac = Pbse-P1). The specified pressure corresponds to P1 a change in the fuel pressure PQ, which is independent of a state in which the needle valve 22nd during a valve-opening drive operation or a valve-closing drive operation of the fuel injection valve 20th assumes a valve-closed position, ie a change in the fuel pressure PQ that does not cause the needle valve to move 22nd contributes.

Thereafter, a first-order differential value d (PQ) / dt is calculated based on a period of time for the fuel pressure PQ for a period in which the fuel pressure PQ decreases immediately after the start of fuel injection. A tangent L1 of a time-dependent waveform of the fuel pressure PQ at a point where the first-order differential value becomes its smallest value, that is, a downward slope of the fuel pressure PQ becomes its maximum value, is obtained. Furthermore, an intersection point A of the tangent L1 and the operating pressure Pac is calculated. A point of time corresponding to a point AA obtained by moving back the intersection point A in the past by the subsequent delay in the detection of the fuel pressure PQ is identified as a valve opening operation start Tos. The delay of the detection is a period of time corresponding to a delay in a timing of the change in the fuel pressure PQ with respect to a timing of the change in the pressure in the nozzle chamber 25th of the fuel injection valve 20th (please refer 2 ) and is determined by the distance between the nozzle chamber 25th and the pressure sensor 41 causes.

In addition, a first-order differential value is calculated for the fuel pressure PQ for a period in which the fuel pressure PQ first drops and then increases immediately after the start of fuel injection. A tangent L2 of the time-dependent waveform of the fuel pressure PQ at a point where the first-order differential value peaks, that is, at a point where an increase in the fuel pressure PQ peaks, is obtained, and an intersection point B of the Tangent L2 and the operating pressure Pac are calculated. A time point corresponding to a point BB obtained by moving the intersection point B back in the past by a detection delay is identified as a valve-closing operation end Tce.

Further, an intersection point C of the tangents L1 and L2 is calculated, and the difference between the fuel pressure PQ and the operating pressure Pac at the intersection point C (ΔP [ΔP = Pac-PQ], which corresponds to a hypothetical pressure decrease) is found. In addition, a value obtained by multiplying the hypothetical pressure decrease ΔP by a factor G1 set based on the required injection amount TAU is calculated as the hypothetical maximum fuel injection rate VRt (VRt = ΔP × G1). In addition, a value obtained by multiplying the hypothetical maximum fuel injection rate VRt by a factor G2 set based on the required injection amount TAU is calculated as the maximum injection rate Rt (Rt = VRt × G2).

Then, a time point CC obtained by moving the intersection point C back in the past by a detection delay is calculated. Further, a point D is specified at which the hypothetical maximum fuel injection rate VRt is reached at time CC. A time point corresponding to an intersection E of a line L3 connecting the point D with the valve opening operation start Tos (more precisely, a point where the fuel injection rate at time Tos is 0) and the maximum injection rate Rt is specified as time Toe at which the maximum injection rate is reached.

A point of time corresponding to an intersection F of a line L4 connecting the point D and the valve-closing operation end Tce (more specifically, the point at which the fuel injection rate at the point of time Tos is 0) and the maximum injection rate Rt is identified as an injection rate decrease start Tcs .

Further, a time-dependent fuel injection waveform with a trapezoidal shape formed from the valve opening operation start Tos, the timing Toe at which the maximum injection rate is reached, the injection rate decrease start Tcs, the valve closing operation end Tce and the maximum injection rate Rt, as the waveform of the fuel injection rate im Collection period used.

Now referring to 4th and 5 a process (correction process) for correcting various control target values in fuel injection control based on the waveform in the detection period will be described in detail.

4th Fig. 13 is a flowchart showing a specific flow of the correction process. A series of processes shown in this flowchart shows the theoretical flow of performing correction processing, and an actual process is performed by the electronic control unit 40 carried out as an interruption process at specified intervals. 5 Fig. 13 shows an example of a relationship between a waveform in the detection period and the following waveform in a basic period.

As in 4th In the correction process, as described above, first, a waveform is formed in a detection period during the execution of fuel injection based on the fuel pressure PQ (step S101). In addition, a basic value of the time-dependent waveform of the fuel injection rate (a Waveform in a basic period) when performing fuel injection based on the operating state of the internal combustion engine 11 , for example, the accelerator operation amount ACC and the engine speed NE are set (step S102). In the present embodiment, a relationship is established between the operating state of the internal combustion engine 11 and the waveform in the basic period suitable for the operating condition is determined in advance based on results of experiments and simulations, and the relationship is established in the electronic control unit 40 saved. In the process in step S102, the waveform in the basic period is changed at any time based on the relationship based on the current operating state of the internal combustion engine 11 set.

As in 5 illustrated, a time-dependent trapezoidal waveform defined by a valve opening operation start Tosb, a point of time Toeb at which a maximum injection rate is reached, an injection rate lowering start Tcsb, a valve closing operation end Tceb and a maximum injection rate is set as a waveform in the basic period (a line, formed by alternating long and short strokes).

The waveform in the basic period is compared with the waveform in the detection period (solid line), and a correction amount K1 and a correction amount K2 are calculated. The correction variable K1 is used to correct a control target value for the start of the fuel injection (the required start of injection Tst) on the basis of the comparison. The correction quantity K2 is used to correct a control target value for the execution duration of the fuel injection (the required injection duration Ttm). More specifically, a difference ΔTos (ΔTos = Tosb - Tos) between the valve opening operation start Tosb in the waveform in the basic period and the valve opening operation start Tos in the waveform in the detection period is calculated and stored as a correction quantity K1 (step S103 in FIG 4th ). In addition, the difference ΔTcs (ΔTcs = ΔTcsb - Tcs) between the injection rate lowering start Tcsb in the waveform in the basic period ( 5 ) and the start of injection rate decrease Tcs in the waveform in the detection period and stored as a correction quantity K2 (step S104 in FIG 4th ).

After the correction variables K1 and K2 have been calculated in this way, this process is temporarily suspended.

In performing the fuel injection control, a value that is corrected by correcting the required injection start Tst using the correction amount K1 (in the present embodiment, a value obtained by adding the correction amount K1 to the required injection start Tst) becomes the final required one Injection start Tst is calculated. Thus, by calculating the required injection start Tst, the difference between the valve opening operation start Tosb in the waveform in the basic period and the valve opening operation start Tos in the waveform in the detection period can be reduced. Therefore, with such a configuration, the start of fuel injection is set with great accuracy so that it corresponds to the operating state of the internal combustion engine 11 is equivalent to.

In addition, a value obtained by correcting the required injection period Ttm using the correction amount K2 (in the present embodiment, a value obtained by adding the correction amount K2 to the required injection period Ttm) is calculated as the final required injection period Ttm. Thus, by calculating the required injection duration Ttm, the difference between the injection rate decrease start Tcsb in the waveform in the basic period and the injection rate decrease start Tcs in the waveform in the detection period can be decreased. Therefore, with such a design, the timing at which the fuel injection rate starts to decrease is set with great accuracy so that it corresponds to the operating state of the internal combustion engine 11 is equivalent to.

In the present embodiment, the required start of injection Tst or the required injection duration Ttm is thus determined on the basis of the difference between the current operating parameters of the fuel injection valve 20th (more precisely the waveform in the recording period) and the specified basic operating key figures (more precisely the waveform in the basic period) corrected. Therefore, the difference between the current operating index of the fuel injection valve 20th and the basic operation index (the operation index of the fuel injection valve with a standard index) can be decreased. As a result, the injection start and the injection amount from each fuel injection valve become 20th during fuel injection in accordance with the operating state of the internal combustion engine 11 suitably adjusted.

In the present embodiment, control (an index value acquisition process) is performed to determine the index value of the cetane number of the fuel used for combustion in the internal combustion engine 11 should be used to capture. The following is a summary of the process for acquiring the index value.

In the index value acquisition process, an execution condition is set that includes a condition that the thrust cut control is performed ([Condition 1], described below). If the implementation requirement is met, fuel is injected into the internal combustion engine 11 is performed with a predetermined small amount of FQ (for example, several cubic millimeters), and an index value of the output torque of the internal combustion engine 11 generated due to the execution of fuel injection (an amount of rotation speed fluctuation ΣΔNE, described below) is detected as an index value of the cetane number of the fuel. The greater the generated output torque of the internal combustion engine 11 is, the larger the value detected for the amount of speed fluctuation ΣΔNE.

The higher the cetane number of the fuel, which is used in the internal combustion engine 11 is to be delivered, the easier the fuel will ignite and the more completely the fuel will be burned. Therefore, the engine torque generated by combustion of the fuel becomes larger. In the determination control of the present embodiment, the index value of the cetane number of the fuel is determined based on a relationship of the cetane number of the fuel and the output torque of the internal combustion engine 11 recorded.

A flow of performing the process of acquiring the index value is described in detail below.

6th Fig. 13 is a flowchart showing a specific flow of the index value acquisition process. A series of processes shown in this flowchart shows the theoretical flow of performing the index value acquisition process, and an actual process is performed by the electronic control unit 40 performed as an interrupt process for every given cycle.

As in 6th As shown, it is first determined in the process whether or not an execution requirement is met (step S201). It is determined here that the implementation requirement is met if requirement 1 to requirement 3, which are described below, are all met.

[Condition 1] The thrust cut control is being performed.

[Prerequisite 2] The clutch mechanism 13th is in the operating state in which the clutch mechanism is the crankshaft 12th and the manual transmission 14th separates from each other. More precisely, the clutch actuator is being actuated.

[Prerequisite 3] The correction process is being carried out properly. More precisely, none of the correction variables K1, K2 that are calculated in the correction process is an upper limit value or a lower limit value.

If the performance requirement is not met (step S201: NO), the following process, i.e., a process for acquiring the index value of the cetane number of the fuel, is not performed, but the present process is temporarily suspended.

Thereafter, when the present process has been repeatedly performed until the execution requirement is met (step S201: YES), the process for acquiring the index value of the cetane number of the fuel is started.

More precisely, a control target value for a predetermined fuel injection start (target injection start TQst) and a control target value for the fuel injection duration (target injection duration TQtm) are first determined using the correction variables K1, K2, which are specified in the in 4th and 5 have been calculated are corrected (step S202 in FIG 6th ). More specifically, a value obtained by adding the correction quantity K1 to the target injection start TQst is set as the new target injection start TQst, and a value obtained by adding the correction quantity K2 to the target injection duration TQtm is set as the new target injection Injection duration TQtm set.

A drive control of the fuel injection valve 20th is carried out on the basis of the target start of injection TQst and the target injection duration TQtm, so that a fuel injection from the fuel injection valve 20th is performed (step S203). By this drive control of the fuel injection valve 20th a predetermined amount FQ of fuel is discharged from the fuel injection valve 20th injected at times when a variation in the amount of speed fluctuation ΣΔNE can be suppressed. In the present embodiment, in the process of step S203, fuel injection is performed using a predetermined one of the fuel injection valves 20th (in the present embodiment of the fuel injection valve 20th that on the cylinder 16 [No. 1] is appropriate). As for the correction quantities K1, K2 used in the present process, a value is also used which corresponds to the value given by the fuel injection valves 20th (in the present Embodiment the fuel injection valve 20th that on the cylinder 16 [No. 1] is appropriate) is calculated.

Thereafter, the amount of speed fluctuation ΣΔNE is used as an index value of the output torque of the internal combustion engine 11 generated by injecting the predetermined amount of fuel FQ is detected and stored (step S204), and thereafter the present process is temporarily suspended. More specifically, the detection of the amount of speed fluctuation ΣΔNE is performed as follows. As in 7th is shown, in the device according to the present embodiment, the engine speed is regularly detected at predetermined times, and the difference ΔNE (ΔNE = NE - NEi) between the engine speed NE and an engine speed NEi that has been detected in the past (one of the currently seen from the nth, in the present embodiment a third), is calculated for each acquisition. An integrated value for a variation in the difference ΔNE as fuel injection is performed (which is a value corresponding to an area indicated by a diagonal line in 7th is calculated, and the integrated value is also stored as the amount of speed fluctuation ΣΔNE. Since changes in the engine speed NE or the difference ΔNE in 7th are shown in a simplified manner so that a method for calculating the magnitude of the speed fluctuation ΣΔNE can be better understood, they differ somewhat from current changes.

In the present embodiment, basically, one of the lower, middle and upper cetane number regions is specified based on the amount of speed fluctuation ΣΔNE detected in the process of detecting the first index value, and the specified region is further specified in the electronic control unit 40 saved. More specifically, it is determined that the cetane number is in the lower cetane number region when the amount of speed fluctuation ΣΔNE is smaller than a predetermined value PL (ΣΔNE <PL), it is determined that the cetane number is in the middle cetane number region when the amount of speed fluctuation ΣΔNE is equal to or larger than the predetermined value PL and is smaller than a predetermined value PH (PL ≤ ΣΔNE <PH), and it is determined that the cetane number is in the upper cetane number region when the amount of speed fluctuation ΣΔNE exceeds the predetermined value PH is equal to or greater than this (ΣΔNE ≥ PH). The fuel injection control is performed in the execution mode corresponding to the cetane number region thus specified.

When the cetane number of the fuel going to the internal combustion engine 11 is to be supplied is low, the ignition delay is lengthened so that the combustion state of the fuel tends to deteriorate. In idle mode immediately after initiating the start of the internal combustion engine 11 is also the amount of fuel that goes into the cylinders 16 should be injected, small, and the temperature in the cylinders 16 is low. For this reason, the state of combustion of the fuel tends to deteriorate. In the device according to the present embodiment, it is therefore particularly clear that the combustion state of the fuel during an idling operation immediately after the initiation of the start of the internal combustion engine 11 and if it is determined that the cetane number is in the lower cetane number region, it tends to deteriorate and misfires easily.

In this regard, in the present embodiment, during the execution period immediately from the initiation of the start of the internal combustion engine 11 and when the lower cetane number region is stored (in a particular situation), the idle target EGR rate Tegr is set to 0 and the EGR amount of the EGR device 50 is set to 0. When idling immediately after initiating the start of the internal combustion engine 11 is performed in a situation in which the lower cetane number region is stored, that is, when the state of combustion of the fuel tends to be more prone to an error in regulation of the EGR amount and the state of combustion of the fuel is likely to be unstable, as a result, the state of combustion of the fuel in the cylinders 16 of the internal combustion engine 11 can be improved in accordance with the interruption of the EGR gas recirculation. Therefore, the occurrence of misfire can be suppressed.

In order to improve the combustion state of the idling fuel in the particular situation, apart from setting the EGR amount in the idling operation to 0, the EGR amount may be decreased compared to a non-particular situation. Because of the volume of the EGR line 51 or a portion of a connecting part of the EGR line 51 in the suction line 17th to the cylinders 16 of the internal combustion engine 11 in the EGR device 50 may occur a delay in a change in the amount of EGR with respect to a change in the opening of the EGR valve 52 cannot be avoided. For this reason, the responsiveness or stability of the change in the amount of EGR is related to the change in the opening of the EGR valve 52 bad, and it is difficult to control the amount of EGR by the EGR device 50 fine to regulate. As a result, it is apparent that there is regulation of the amount of EGR by the EGR device 50 regulatory errors can easily occur. When the EGR amount is too much due to the regulation error is increased, the state of combustion of the fuel may deteriorate. In addition, if the amount of EGR is decreased too much due to the regulation error, the combustion temperature of the fuel in the cylinders may increase 16 increase, which leads to an increase in nitrogen oxide (NOx) in the exhaust gas.

In this regard, in the present embodiment, in a particular situation, that is, when the combustion state of the fuel tends to be largely affected by the regulation error of the EGR amount and the combustion state of the fuel is likely to be unstable, the regulation error of the EGR amount per se is eliminated . Therefore, the influence of the regulation error on the combustion state of the fuel can be eliminated.

As described above, the EGR amount in the idling operation is set to 0 in the particular situation, so that the combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 is improved. Therefore, the occurrence of misfire can be suppressed. However, if the EGR amount is simply set to 0, the combustion temperature of the fuel in the cylinders rises 16 of the internal combustion engine 11 strong. For this reason, the amount of NOx in the exhaust gas could increase significantly.

In this regard, in the present embodiment, the fuel injection start in the idling mode is set to a later point in time compared with the non-special situation, which corresponds to the setting of the EGR amount in the idling mode to 0 in the special situation. The non-specific situation in the present embodiment means a time at which the middle cetane number region is stored, a time at which the upper cetane number region is stored, or a time at which the execution period after the initiation of the start of the internal combustion engine 11 expires.

By setting a later point in time than the start of fuel injection, the ignition point of the fuel in the cylinders becomes 16 of the internal combustion engine 11 delayed. Therefore, the combustion temperature of the fuel is lowered accordingly, so that the amount of NOx is decreased. In the present embodiment, a fuel injection start (more specifically, the required injection start Tst) at which suppression of deterioration of a combustion state and control of a NOx discharge amount are compatible with each other is set by the fuel injection control.

In addition, in the present embodiment, the state of combustion of the fuel in the cylinders 16 of the internal combustion engine 11 can be set with greater accuracy in the idling operation in the particular situation by setting in which the fuel injection start is adjusted as compared with the setting made by regulating the amount of EGR. According to the present embodiment, therefore, it is possible to check the combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 set correctly when using fuel with a low cetane number. Therefore, suppression of occurrence of misfire can be made compatible with control of a NOx discharge amount.

A detailed description will be given of a process for setting the EGR amount to 0 in the particular situation and a process for delaying the start of fuel injection.

First, the process for setting the EGR amount to 0 during idling in the particular situation is referring to FIG 8th described.

8th Fig. 13 shows a flow of executing a process related to EGR control (EGR control process). A process sequence shown in the flowchart of 8th is shown by the electronic control unit 40 performed as an interrupt process for every given cycle.

As in 8th is shown, it is first determined in the process whether or not both condition 4 and condition 5 are met (step S301).

[Prerequisite 4] The lower cetane number region is specified and in the electronic storage unit 40 saved.

[Prerequisite 5] There is an implementation period from the initiation of the start of the internal combustion engine 11 until the start of actuation of the accelerator actuation element (an actuation to increase the accelerator actuation scope ACC to greater than 0). More specifically, the accelerator operation amount ACC is continued to be held in state 0 after the operation switch 48 has been actuated to drive the internal combustion engine 11 to start.

When both [Condition 4] and [Condition 5] are satisfied (step S301: YES), the state of combustion of the fuel tends to be highly susceptible to the regulation error of the EGR amount, and the state of combustion of the fuel is likely during this time unstable. As a result, 0 is set as the target ARG rate Tegr, and the EGR amount is set to 0 (step S302).

On the other hand, when the condition 4 or the condition 5 is not satisfied (step S301: NO), normal control (more specifically, the operation control of the EGR valve 52 which corresponds to the target EGR rate set based on the engine speed NE and the required injection amount TAU) is performed as the EGR control process (step S303). More specifically, when condition 4 is not met, the normal control is performed as the EGR control process on the assumption that there is little possibility of excessive deterioration in the fuel combustion state because at that time the middle cetane number region or the upper cetane number region is specified and is stored in the electronic control device. In addition, when condition 5 is not met, normal control is performed as the EGR control process on the assumption that there is little possibility of excessive deterioration in the fuel combustion state because of the temperature in the cylinders 16 of the internal combustion engine 11 increases with continued engine operation after starting.

A process for delaying fuel injection start (an injection start delay process) will now be described with reference to FIG 9 described.

9 Fig. 13 shows a flow for performing the injection start delay process. A process flow that is shown in the flowchart of 9 is shown for each given cycle by the electronic control unit 40 performed as an interruption process.

As in 9 1, it is first determined in the process whether the EGR opening degree VR is equal to or smaller than a predetermined opening degree (for example, an opening degree that is slightly larger than an opening degree when the valve is closed) (step S401). In the process, it is determined whether the engine speed NE is equal to or lower than a predetermined speed (for example, a speed [1300 revolutions / minute] corresponding to an upper limit for the engine speed NE in idling mode) (step S402), and further becomes determines whether the required injection amount TAU is equal to or less than a predetermined amount (for example, the amount corresponding to an upper limit value for the fuel injection amount in the idling mode) (step S403).

When the EGR opening degree VR is equal to or smaller than the predetermined opening degree (step S401: YES), it is determined that the EGR amount is set to 0 at that time. When the engine speed NE is equal to or less than the predetermined speed (step S402: YES) and when the required injection amount TAU is equal to or less than the predetermined amount (step S403: YES), it is determined that the engine 11 has been brought into the idle operating state. Accordingly, when all the determinations in steps S401 to S404 are affirmative, it is determined that both the condition 4 and the condition 5 in the EGR control process are satisfied (see FIG 8th ) and the EGR amount is set to 0. In other words, the lower cetane number region is stored at this time, and the execution period from the initiation of the start of the internal combustion engine 11 until the start of manipulation of the accelerator actuator is there. Therefore, it is determined that the EGR amount is set to 0 in order to improve the combustion state of the fuel and suppress misfires.

In this case (all of steps S401 to S403 are YES), it is further determined whether or not the outside pressure is higher than a decision pressure (e.g., 80 kPa) (step S404). When the external pressure is equal to or higher than the decision pressure (step S404: YES), fuel injection control (delay control) is performed in an execution manner in which the delayed start is set as the fuel injection start (step S405).

In the present embodiment, as a computational map used for setting the required start of injection Tst, a computational map is set up which corresponds to a situation in which the EGR amount is set to 0 in the idling operation in the particular situation, that is, a computational map MLF in addition to the calculation maps ML, MM and MH described above, in which a comparatively later point in time is set. More specifically, a relationship between the engine operating state determined from the required injection amount TAU and the engine speed NE and the required injection start Tst, which corresponds to the situation in which the EGR amount is set to 0 in the idling operation in the particular situation, is made in advance is obtained based on the results of various experiments or simulations, and further, the relationship is used as a calculation map MLF in the electronic control unit 40 saved.

More precisely, in the process of step S405, the computation map MLF is selected from the computation maps. During the subsequent fuel In injection control, the required start of injection Tst is set on the basis of the required injection quantity TAU and the engine speed NE on the basis of the computational map MLF.

On the other hand, when the EGR opening degree VR is larger than the predetermined opening degree (step S401: NO), the fuel injection control (the normal control) in the execution mode in which an earlier timing than the fuel injection start is carried out on the assumption indicates that the EGR amount is not set to 0 at this time (step S406). More specifically, in the normal control, any one of the calculation maps corresponding to the cetane number regions stored at that time, that is, the calculation maps ML, MM and MH, is selected, and the required injection start Tst is then determined based on the required injection amount TAU and the engine speed NE set on the basis of the calculation map selected in this way. In addition, when the engine speed NE is higher than a predetermined speed (step S402: NO), or when the required injection amount TAU is greater than a predetermined amount (step S403: NO), normal control is performed assuming that the engine 11 is not set to the idle state (step S406).

According to the present embodiment, the process of setting the EGR amount to 0 (the process of step S302 in FIG 8th ) and the process of setting a point later than the fuel injection start (the process of step S405 in FIG 9 ) only for an implementation period from the initiation of the start of the internal combustion engine 11 executed until the manipulation of the accelerator actuator is started. Because of this, it is only when the temperature of the cylinder 16 of the internal combustion engine 11 immediately after the initiation of the start is low, that is, only for a period in which the state of combustion of the fuel in the cylinders 16 tends to be unstable, it is possible to set a process for implementing the setting of the combustion state of the fuel (the process for setting the EGR amount to 0 and the process for setting a point later than fuel injection start) with high accuracy.

On the other hand, if the outside pressure is equal to or higher than the decision pressure (step S404: NO), normal control is performed (step S406). When the external pressure is low, the density of the air is low, so the amount of oxygen contained in the intake air is small. For this reason, the state of combustion of the fuel is in the cylinders 16 of the internal combustion engine tends to deteriorate, so that misfires can easily occur. According to the present embodiment, if misfires can easily occur because of the low external pressure, the arithmetic map MLF can be selected, whereby the required start of injection Tst is set to a later point in time, that is, the change of the required start of injection Tst to a side, where the state of combustion of the fuel is caused to deteriorate can be prevented. Therefore, the occurrence of misfire can be reliably suppressed. If the external pressure is higher than the decision pressure (step S404: YES), that is, if misfires are comparatively difficult to cause, a later point in time than the required start of injection Tst is set on the basis of the arithmetic map MLF. Therefore, the discharge amount of NOx can be appropriately controlled. In the present embodiment, a decision pressure with which the occurrence of idling misfire can be reliably suppressed in the particular situation is obtained in advance on the basis of results of various experiments and simulations and in the electronic storage unit 40 saved.

The execution modes of the process for setting the EGR amount in the idling operation in the particular situation to 0 and the process for delaying the start of fuel injection will be described below with reference to FIG 10 described.

10 shows an example of the execution modes of the processes. In 10 Solid lines indicate the execution mode of each of the processes in the device according to the present embodiment, and lines formed alternately by a long stroke and a short stroke indicate an execution mode of each process in a device according to a comparative example in which the EGR Quantity is not set to 0 and the start of fuel injection is not delayed. Also shows a line in 10 , which is formed alternately by one long bar and two short bars, indicates changes in the NOx discharge amount in the case where the EGR amount is set to 0 and the start of fuel injection is not delayed.

In the example of 10 becomes the power switch 48 is turned ON at a time point t11 so that starting the internal combustion engine 11 is initiated. At this time, the lower cetane number region is stored and the accelerator operating member is not subject to manipulation (the amount of manipulation of the accelerator ACC = 0). For this reason, 0 is set as the target EGR rate so that the EGR opening degree VR is set to an opening (VR = 0) corresponding to the valve closing state. At that time, beyond that Compared to a time which excludes the execution period immediately after the initiation of the start of the internal combustion engine MLF, a later point in time than the required start of injection Tst is set on the basis of the calculation map, which corresponds to a part that is shown in the drawing in a white arrow.

At this time, in the device according to the comparative example shown in the lines shown in FIG 10 are formed alternately by a long bar and a short bar, the discharge amount of NOx is controlled to be quite small, but there will be deterioration in the combustion state of the fuel in the cylinders 16 causes what causes misfire or smoke to occur. On the other hand, in the device shown in the line shown in FIG 10 alternating with one long line and two short lines, the state of combustion of the fuel in the cylinders 16 of the internal combustion engine 11 sufficiently improved to prevent misfire or smoke from occurring. However, since the combustion temperature of the fuel rises sharply, the discharge amount of NOx also rises considerably.

On the other hand, in the device according to the present embodiment, the EGR amount is set to 0, and a later start at times t11 to t12 is set as the fuel injection start. Therefore, the discharge amount of NOx can be prevented from becoming significantly larger as in the device shown in the line formed by one long dash and two short dashes alternately, and misfiring or prevention can be prevented smoke development occurs, as in the device according to the comparative example, which is formed alternately by a long line and a short line. According to the present embodiment, the state of combustion of the fuel in the cylinders can thus be determined 16 of the internal combustion engine 11 properly adjusted when using the low cetane number fuel. As a result, the suppression of occurrence of misfire and the control of the NOx discharge amount can be made compatible with each other.

In the present example, when the manipulation of the accelerator operating element is started at time t12, the execution of the process for setting the EGR amount to 0 and the process for delaying the start of fuel injection are interrupted or terminated. At this time, the operation control of the EGR valve becomes 52 carried out depending on the target EGR rate, which is set on the basis of the engine speed NE and the required injection quantity TAU, and the drive control of the fuel injection valve 20th is carried out as a function of the required start of fuel injection Tst, which is set on the basis of one of the computation maps ML, MM and MH on the basis of the extent of the manipulation of the accelerator and the engine speed NE.

• (1) Für den Durchführungszeitraum unmittelbar nach der Initiierung des Starts des Verbrennungsmotors 11 und in der besonderen Situation, in der die untere Cetanzahlregion gespeichert ist, wird die AGR-Menge im Leerlaufbetrieb auf 0 eingestellt und der erforderliche Zündzeitpunkt Tst im Leerlaufbetrieb wird im Vergleich zu einer nicht-besonderen Situation nach hinten verstellt. Daher kann der Verbrennungszustand des Kraftstoffs in den Zylindern 16 des Verbrennungsmotors 11 bei Verwendung des Kraftstoffs mit niedriger Cetanzahl ordnungsgemäß eingestellt werden, wodurch bewirkt wird, dass die Unterdrückung des Auftretens von Fehlzündungen und die Steuerung der NOx-Abgabemenge miteinander kompatibel sind.
• (2) Die AGR-Menge im Leerlaufbetrieb in der besonderen Situation wird auf 0 eingestellt. Daher kann der Einfluss des Regulierungsfehlers der AGR-Menge auf den Verbrennungszustand des Kraftstoffs eliminiert werden, wodurch der Verbrennungszustand des Kraftstoffs mit größerer Genauigkeit eingestellt wird.
• (3) Unter der Voraussetzung, dass der Außendruck dem Entscheidungsdruck gleich ist oder höher ist als dieser, wird der Prozess zum Einstellen eines früheren Zeitpunkts als Kraftstoff-Einspritzungsbeginn (der Prozess des Schritts S405 in 9) durchgeführt.Daher kann die Änderung des erforderlichen Einspritzungsbeginns Tst zu der Seite, wo eine Verschlechterung des Verbrennungszustands des Kraftstoffs bewirkt wird, wenn der Außendruck niedrig ist und es leicht zu Fehlzündungen kommen kann, verhindert werden. Infolgedessen kann das Auftreten von Fehlzündungen leicht verhindert werden. Wenn es wegen eines hohen Außendrucks vergleichsweise schwierig ist, das Auftreten von Fehlzündungen zu bewirken, wird außerdem zugelassen, dass der erforderliche Einspritzungsbeginn nach hinten verstellt wird. Daher kann die NOx-Abgabemenge auf geeignete Weise unterdrückt werden.
• (4) Das Verfahren zum Einstellen der AGR-Menge auf 0 (der Prozess von Schritt S302 in 8) und der Prozess zur Verzögerung des Kraftstoff-Einspritzungsbeginns (der Prozess von Schritt S405 in 9) werden nur für den Durchführungszeitraum nach Initiierung des Starts des Verbrennungsmotors 11 bis zum Start der Manipulierung des Beschleunigerbetätigungselements durchgeführt. Daher ist es möglich, den Prozess zur Implementierung der Einstellung des Verbrennungszustands des Kraftstoffs mit hoher Präzision nur in einem Zeitraum durchzuführen, in dem der Verbrennungszustand des Kraftstoffs im Zylinder 16 des Verbrennungsmotors 11 wahrscheinlich instabil ist.

As described above, according to the present embodiment, advantages described below can be obtained.

• (1) For the implementation period immediately after the initiation of the start of the internal combustion engine 11 and in the particular situation in which the lower cetane number region is stored, the EGR amount in the idling mode is set to 0 and the required ignition timing Tst in the idling mode is retarded compared to a non-particular situation. Therefore, the state of combustion of the fuel in the cylinders 16 of the internal combustion engine 11 when using the low cetane number fuel are properly adjusted, thereby making the suppression of occurrence of misfire and the control of the NOx discharge amount compatible with each other.
• (2) The EGR amount in idle operation in the special situation is set to 0. Therefore, the influence of the regulation error of the EGR amount on the combustion state of the fuel can be eliminated, thereby adjusting the combustion state of the fuel with greater accuracy.
• (3) Provided that the external pressure is equal to or higher than the decision pressure, the process of setting an earlier timing than the fuel injection start (the process of step S405 in FIG 9 Therefore, the change in the required injection start Tst to the side where the combustion state of the fuel is caused to deteriorate when the external pressure is low and misfiring is easy can be prevented. As a result, the occurrence of misfire can be easily prevented. In addition, when it is comparatively difficult to cause misfire to occur because of high external pressure, the required start of injection is allowed to be retarded. Therefore, the NOx discharge amount can be suppressed appropriately.
• (4) The method of setting the EGR amount to 0 (the process of step S302 in 8th ) and the process of delaying fuel injection start (the process of step S405 in 9 ) are only for the implementation period after the initiation of the start of the internal combustion engine 11 carried out until the manipulation of the accelerator actuator is started. Therefore, it is possible to perform the process of implementing the adjustment of the combustion state of the fuel with high precision only in a period when the combustion state of the fuel in the cylinder 16 of the internal combustion engine 11 is likely to be unstable.

The embodiment described above can be changed and carried out in the following manner.

Instead of the processes of Steps S401 to S403, the process of determining whether or not both [Condition 4] and [Condition 5] are satisfied may be performed. By means of such a device it is also possible to set the required ignition time Tst in idle operation in comparison to the non-special situation in the implementation period immediately after the initiation of the start of the internal combustion engine 11 and in the particular situation in which the lower cetane number region is stored, to be adjusted backwards.

The setting of the required injection start Tst can be carried out using an arithmetic expression as well as the arithmetic map.

The setting of the required injection start Tst in the idling operation in the particular situation can be carried out in the following manner. In other words, the required start of injection Tst is set from the calculation map ML based on the engine speed NE and the required injection amount TAU, and a retardation correction quantity is also calculated based on the engine speed NE and the required injection amount TAU. A value obtained by correcting the required injection start Tst with the retardation correction amount is set to be a final required injection start Tst.

The process of step S404 in 9 can be omitted. In other words, it is also possible to execute the process for setting the later injection start Tst independently of the external pressure (process of step S405 in FIG 9 ).

In the special situation, in addition to setting the EGR amount to 0, it is also possible to release the EGR gas by slightly opening the EGR valve 52 attributed to idle in a small amount. In short, it is preferable to reduce the amount of EGR in the idling operation in the particular situation compared to the amount of EGR in the non-particular situation. With this device, it is also possible to correct the regulation error of the EGR amount corresponding to a decrease in the absolute amount of the EGR amount during idling in the particular situation, that is, when the combustion state of the fuel tends to be largely influenced by the regulation error of the EGR amount and the The state of combustion of the fuel is likely to be unstable, decrease. Therefore, the influence of the regulation error of the EGR amount on the combustion state of the fuel can be reduced.

Only for the implementation period from the initiation of the start of the internal combustion engine 11 until the accelerator operating member manipulation is started, the process of setting the EGR amount to 0 (the process of step S302 in FIG 8th ) and the process of setting a point later than the fuel injection start (the process of step S405 in FIG 9 ) executed. Instead, it is also possible to carry out the processes only for the execution period in which a certain predetermined period of time from the initiation of the start of the internal combustion engine 11 expires. For example, the specific time period includes a specific time (for example, several seconds to several tens of seconds), a time period that is necessary until the integrated value of the fuel injection amount reaches a predetermined value, a time period until the integrated value of the intake amount reaches a predetermined value , and the same. In short, for a period of time necessary to reach the temperature of the cylinders 16 of the internal combustion engine 11 is completely increased so that the combustion state of the fuel is improved, the process of setting the EGR amount to 0 and the process of setting a point later than the fuel injection start are preferably performed.

In the case of an error in the start of fuel injection or the fuel injection amount caused by the initial individual difference, time-dependent changes or the like in the fuel injection valve 20th is appropriately suppressed, it is also possible to omit the process of correcting the target injection start TQst and the target injection duration TQtm with the correction quantities K1 and K2 (step S202 in FIG 6th ).

Also, by appropriately changing the configuration, it is possible to apply the control device according to the embodiment described above to a device for determining one of two regions obtained by dividing an index value of a cetane number of the fuel (the amount of the Speed fluctuation ΣΔNE), or to use a device for determining one of four or more regions.

By appropriately changing the configuration, it is also possible to apply the control device according to the above-described embodiment to a device that can reduce the amount of rotational speed fluctuation ΣΔNE that occurs in the electronic control device 40 is stored, used as a value corresponding to the cetane number of the fuel supplied to the internal combustion engine 11 should be delivered (more precisely a cetane number index value) without specifying the cetane number region based on the extent of the speed fluctuation ΣΔNE. When the amount of the rotational speed fluctuation ΣΔNE in such a device is smaller than a predetermined value, it is preferably determined that the cetane number of the fuel to be supplied to the internal combustion engine is small, whereby the process for adjusting the EGR amount in the idling mode in the special situation to 0 and the process of setting a point in time later than the fuel injection start can be performed.

A value other than the amount of speed fluctuation ΣΔNE can be used as an index value of the output torque of the internal combustion engine 11 be calculated. For example, the engine speed NE when the fuel injection is performed while the index value detection process is performed and the engine speed NE immediately before the fuel injection is performed are each detected, and the difference between the speeds is calculated. Thus, the difference can be used as an index value.

A mode for attaching the pressure sensor 41 can optionally except a mode for direct mounting of the pressure sensor 41 on the fuel injection valve 20th can be changed as long as it is possible, a pressure for an index of the fuel pressure in the fuel injection valve 20th (more precisely in the nozzle chamber 25th ), that is, to appropriately detect the change in fuel pressure with a variation in fuel pressure. The pressure sensor on the branch line can be more precise 31a or the common pressure line 34 be attached.

Instead of the fuel injector 20th of the type used by the piezoelectric actuator 29 is controlled, a fuel injection valve of a type can be used that is controlled by an electromagnetic actuator that includes, for example, a solenoid or the like.

The control device according to the embodiment described above can be applied to the vehicle 10 that with the clutch mechanism 13th and the manual transmission 14th can also be applied to a vehicle equipped with a torque converter and an automatic transmission. In such a vehicle, the fuel injection for estimating the cetane number of the fuel is preferably carried out if, for example, requirement 1 and requirement 3 are met. In a vehicle using a torque converter having a lock-up clutch, fuel injection for detecting the index value of the cetane number of the fuel is preferably carried out under the condition that the condition 6 that the lock-up clutch is not brought into an engaged state is reset and that condition 6 is met.

The present invention does not apply to the device for performing the fuel injection for determining the cetane number of the fuel supplied to the internal combustion engine 11 is to be delivered, limited, but can also be applied to a device for performing the method for determining the cetane number of the fuel. The device may include the following device, for example. In other words, first, the pressure in the cylinder of the internal combustion engine (a cylinder pressure) is detected by a cylinder pressure sensor when performing fuel injection for the operation of the internal combustion engine. The timing at which the fuel is actually ignited is calculated based on the cylinder pressure, and an ignition delay time is also calculated based on the timing. Then, a cetane number index value is calculated based on the ignition delay time thus calculated.

The present invention can be applied to an internal combustion engine with a single cylinder, an internal combustion engine with two cylinders, an internal combustion engine with three cylinders, or an internal combustion engine with five or more cylinders in addition to the internal combustion engine having the four cylinders.

List of reference symbols

10

Vehicle,

11

Internal combustion engine,

12th

Crankshaft,

13th

Clutch mechanism,

14th

manual transmission,

15th

Wheel,

16

Cylinder,

17th

Suction line,

18th

Piston,

19th

Exhaust pipe,

20th

Fuel injection valve,

21

Casing,

22nd

Needle valve,

23

Injection port,

24

Feather,

25th

Nozzle chamber,

26th

Pressure chamber,

27

Inlet pipe,

28

Communication line,

29

piezoelectric actuator,

29a

Valve element,

30th

Derivation,

31a

Branch line,

31b

Supply line,

32

Fuel tank,

33

Fuel pump,

34

common pressure line,

35

Return line,

40

electronic control unit,

41

Pressure sensor,

42

Crank sensor,

43

Accelerator sensor,

44

External pressure sensor,

45

Suction sensor,

46

Suction pressure sensor,

47

Opening sensor,

48

Operating switch,

50

EGR device,

51

EGR line,

52

AGR valve.

Claims (3)

Control device for an internal combustion engine (11), the control device comprising: an EGR device (50) for recirculating exhaust gas by returning part of the exhaust gas flowing in an exhaust pipe (19) of the internal combustion engine (11) to an intake pipe; a determining unit for determining a cetane number of fuel to be supplied to the internal combustion engine (11); and a control unit (40), the control unit (40) if the cetane number determined by the determination unit during an execution period which is a period immediately after the initiation of the start of the internal combustion engine (11) until the start of the manipulation of an accelerator actuating element, is low, can reduce an EGR amount by the EGR device (50) in an idling operation and adjusts the fuel injection period backwards compared to other cases. Control device for an internal combustion engine (11) according to Claim 1 wherein the control unit (40) sets the EGR amount to zero. Control device for an internal combustion engine (11) according to Claim 1 or 2 , wherein the control unit (40) carries out the adjustment of the start of fuel injection to the rear, provided that an external pressure is equal to or higher than a predetermined decision pressure.

Images