DE112011100766T5 - Control device for internal combustion engine - Google Patents

Abstract

An EGR apparatus for recycling exhaust gas by returning a part of an exhaust gas flowing in an exhaust passage into an intake passage is fixed to the engine. An electronic control unit performs a process of specifying and storing a cetane number region, which includes a cetane number of fuel supplied to the engine. For an execution period immediately after initiating the start of the engine and in a particular situation where a low cetane number region is stored (t11 to t12), the electronic control unit sets an EGR opening (VR) to 0 in an idle mode and provides a required one Injection start (Tst) in idle mode to a later than in a non-special situation later time.

Description

FIELD OF TECHNOLOGY

The present invention relates to a control apparatus for an internal combustion engine, which 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 elapsed after fuel has been injected into a cylinder through a fuel injection valve (ignition delay). In order to improve the output performances and the emission performances of the internal combustion engine, a control apparatus which regulates an execution mode of an engine control, for example, the injection time and the injection amount in a fuel injection, taking into account this ignition delay, is widely used.

In an internal combustion engine, the lower the cetane number of the fuel used, the longer the ignition delay. Although a performance mode of the engine control at the time of engine delivery is set on the assumption that fuel having a typical cetane number is used, an ignition timing of the fuel is retarded and the combustion state is deteriorated when fuel having a relatively low cetane number, for example Winter fuel being delivered to the fuel tank. In some cases, misfires can occur.

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

Patent Document 1, for example, proposes an internal combustion engine having an exhaust gas recirculation device (EGR) for returning the exhaust gas by returning a part of the exhaust gas flowing through an exhaust pipe of the internal combustion engine into an intake passage and a cetane number of the fuel supplied to the internal combustion engine is to be estimated and provisionally determined and the amount of exhaust gas (an EGR amount) to be returned by the EGR device in the exhaust pipe, is corrected depending on the thus estimated cetane number. In the apparatus, the EGR amount is corrected so as to decrease as the estimated cetane number decreases. As a result, it is possible to improve the combustion state of the fuel, thereby preventing the occurrence of misfires.

DOCUMENT OF THE PRIOR ART

Patent document

Patent Document 1

• posted Japanese Patent No. 2007-285195

SUMMARY OF THE INVENTION

Problems to be solved by the invention.

Usually, an EGR device includes an EGR passage that causes a suction passage and an exhaust passage in an internal combustion engine to communicate with each other, and an EGR valve that changes a flow area of the EGR passage. In the EGR apparatus, an EGR amount is controlled by an operation control of the EGR valve. In the EGR apparatus, due to the volume of the EGR passage, the volume of the portion from the connection part to the EGR passage in the intake passage of the engine to the cylinder of the internal combustion engine, or the like, a delay in a change of an EGR amount with respect to a change of a Opening degree of the EGR valve can not be avoided. For this reason, the responsiveness or the stability of a change in the EGR amount with respect to a change in the opening degree of the EGR valve is poor, and the EGR device can hardly finely control the EGR amount. Therefore, a regulation error in the regulation of the EGR amount by the EGR device easily occurs.

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

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

Means of solving the problems

In order to achieve the object, and according to one aspect of the present invention, there is provided a control apparatus for an internal combustion engine having an EGR apparatus that performs exhaust gas recirculation by introducing a part of the exhaust gas flowing in an exhaust pipe of the internal combustion engine into one Return suction line. The controller estimates a cetane number of fuel to be supplied to the engine. When the cetane number estimated by a determination unit is low during an execution period immediately after initiation of engine startup, an EGR amount is reduced by the EGR device in an idle operation, and a fuel injection start is started Comparison with other cases adjusted to the rear.

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

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 misfires can be suppressed and the emission of nitrogen oxide (NOx) can be suppressed.

The control unit preferably sets the EGR amount to 0. According to this apparatus, the influence of the EGR amount regulation error on the combustion state of the fuel can be eliminated. Therefore, the combustion state of the fuel can be adjusted with greater accuracy.

According to one aspect of the present invention, the retardation of the fuel injection start is performed back 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 reduced, so that the amount of oxygen contained in the intake air is small. For this reason, there is a tendency to deteriorate the combustion state of the fuel in the cylinder of the internal combustion engine, resulting in occurrence of misfires. When the external pressure is low and misfires are likely to occur, according to this device, a delay of the fuel injection start is prevented, that is, a change that deteriorates the combustion state of the internal combustion engine is prevented. Therefore, the occurrence of misfires can be reliably suppressed. In addition, when the external pressure is high and comparatively rare can cause misfire, a change in the fuel injection start is made to be rearward is allowed. As a result, the emission of NOx can be suppressed.

According to one aspect of the present invention, the execution period is set as a period from the initiation of starting of the internal combustion engine to the start of manipulation of an accelerator operation member. According to this apparatus, it is possible to perform the reduction of the EGR amount and the rearward fuel injection start timing to adjust the combustion state with high accuracy only when the temperature in the cylinder of the internal combustion engine is immediately after initiation of the start of the internal combustion engine is low, d. H. only for a certain period of time, in which the combustion state of the fuel in the cylinder is likely to become unstable.

BRIEF DESCRIPTION OF THE DRAWINGS

1 FIG. 12 is a schematic structural view of a control apparatus for an internal combustion engine according to an embodiment of the present invention; FIG.

2 FIG. 12 is a cross-sectional view of a cross-sectional structure of the fuel injection valve; FIG.

3 FIG. 15 is a time chart showing a relationship between changes in the fuel pressure and a waveform of the fuel injection rate and a history of the fuel injection in a detection period; FIG.

4 FIG. 10 is a flowchart showing a procedure in the execution of correction processing; FIG.

5 Fig. 10 is a time chart showing an example of a relationship between a waveform in a detection period and a waveform in a basic period;

6 Fig. 10 is a flowchart showing a specific procedure when performing processing for acquiring a first index value;

7 Fig. 12 is a diagram explaining a method of calculating a magnitude of a rotational speed fluctuation;

8th Fig. 10 is a flowchart showing the procedure in the execution of an EGR control method;

9 Fig. 10 is a flowchart showing the procedure in the implementation of a method for delaying injection start; and

10 Fig. 11 is a timing chart showing an example of a mode of execution for each method.

FACILITIES OF THE EMBODIMENT OF THE INVENTION

Hereinafter, a control apparatus for an internal combustion engine according to an embodiment of the present invention will be described.

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

A suction line 17 is with cylinders 16 of the internal combustion engine 11 connected. Air is passing through the intake pipe 17 in the cylinders 16 of the internal combustion engine 11 sucked. The number of cylinders 16 in the internal combustion engine 11 is four (# 1 to # 4). The internal combustion engine 11 has fuel injectors 20 which are Direktispritzventile, each one of the cylinder 16 correspond. The fuel generated by a valve opening drive operation of the fuel injection valve 20 is injected, in contact with sucked air, in the individual cylinders 16 of the internal combustion engine 11 compressed and heated, ignited and burned. In the internal combustion engine 11 is in the individual cylinders 16 a piston 18 pressed down by energy generated by the combustion of the fuel, causing the crankshaft 12 is made to turn. The gas in the cylinders 16 of the internal combustion engine 11 is burned, as exhaust gas to an exhaust pipe 19 in the internal combustion engine 11 dissipated.

An exhaust gas recirculation (EGR) device 50 , which recirculates exhaust gas, in which it contains a portion of the exhaust gas that is in the exhaust pipe 19 flows, to the intake pipe 17 is back at the internal combustion engine 11 attached. The EGR device 50 has an EGR pipe 51 that causes the suction pipe 17 and the exhaust pipe 19 in the internal combustion engine 11 communicate with each other, and an EGR valve 52 on, that at the AGR line 51 is attached and serves 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 from the exhaust pipe 19 is returned to the intake passage, that is, an EGR amount by changing the opening degree of the EGR valve 52 regulated.

Every fuel injection valve 20 is over a branch line 31a with a common pressure line 34 connected, and the common pressure line 34 is via a supply 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 injectors 20 delivered. There is also a return line 35 with the fuel injection valve 20 connected and with the fuel tank 32 connected. Part of the fuel in the fuel injector 20 is through the return line 35 in the fuel tank 32 brought back.

The internal structure of the fuel injection valve 20 will be described below.

As in 2 is shown is a needle valve 22 in a housing 21 each fuel injector 20 intended. The needle valve 22 is provided in a state in which a reciprocating motion (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 that the needle valve 22 constantly to an injection port 23 pushes down (down in 2 ). A nozzle chamber 25 is at a location on one side of the needle valve 22 (below in 2 ) in the housing 21 formed, and a pressure chamber 26 is on the other side (top in 2 ) educated.

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

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

When in the fuel injector 20 a signal to close the valve in the piezoelectric actuator 29 is input, pulls the piezoelectric actuator 29 together, causing the valve element 29a is moved so that the communication line 28 with the pressure chamber 26 is connected and the return line 35 and the pressure chamber 26 be separated from each other. Thus, a communication of the nozzle chamber 25 with the pressure chamber 26 causes in a state in which the delivery of the fuel in the pressure chamber 26 in the return line 35 (the fuel tank 32 ) is prevented. Because of this, the pressure difference between the nozzle chamber becomes 25 and the pressure chamber 26 greatly reduced, leaving the needle valve 22 by a biasing force of the spring 24 is moved to a position in which it the injection ports 23 closes, and the injection valve 20 Thus, in a state or a position (a valve closing position) is brought, in which no fuel is injected.

In contrast, when a signal to open the valve in the piezoelectric actuator 29 is input, the piezoelectric actuator expands 29 out, causing the valve element 29a is moved so that it is the communication line 28 and the pressure chamber 26 separates from each other and the return line 35 with the pressure chamber 26 combines. Thus, in a state where leakage of the fuel from the nozzle chamber 25 to the pressure chamber 26 prevents part of the fuel in the pressure chamber 26 through the return 35 in the fuel tank 32 recycled. For this reason, the pressure of the fuel in the pressure chamber decreases 26 so that the pressure difference between the pressure chamber 26 and the nozzle chamber 25 gets bigger. Due to this pressure difference, the needle valve becomes 22 against the biasing force of the spring 24 moved and thus from the injection port 23 solved. At the same time, the fuel injection valve 20 is brought into a state (an open valve position), is injected in the fuel.

A pressure sensor 41 is at the fuel injection valve 20 integrated attached. The pressure sensor 41 serves to output a signal corresponding to a fuel pressure PQ in the intake pipe 27 equivalent. Unlike a device that captures a fuel pressure at a location that is away from the fuel injector 20 is, for example, a fuel pressure in the common rail 34 (please refer 1 ), can be a fuel pressure at a section near the injection port 23 of the fuel injection valve 20 are detected and a change in the fuel pressure in the fuel injection valve 20 because of an opening of the fuel injection valve 20 can be captured more accurately. The pressure sensor 41 is for every fuel injector 20 provided, ie for each cylinder 16 of the internal combustion engine 11 ,

As in 1 are shown, various sensors for detecting the operating state as peripheral devices in the internal combustion engine 11 intended. As these sensors are, for example, a crank sensor 42 , the rotational phase and the speed of the crankshaft 12 (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. Also provided are an external pressure sensor 44 for detecting an air pressure outside of the internal combustion engine 11 (the outside air pressure), an intake amount sensor 45 that sucked in the amount of air passing through the intake pipe 17 flows (a line suction amount GA) detected, and a suction pressure sensor 46 that the pressure (a suction pressure PM) in the suction line 17 recorded, provided. Further, an opening sensor 47 for detecting an opening of the EGR valve 52 (an EGR opening degree VR), an operation switch 48 when starting the operation of the internal combustion engine 11 is turned ON and turned OFF at the completion of the operation, and the like.

As peripheral devices of the internal combustion engine 11 Further, for example, is an electronic control unit 40 provided with a microcomputer or the like. The electronic control unit 40 serves as a determination section and a control section, fetches output signals from various sensors, performs various calculations based on the output signals, and performs various controls related to the operation of the internal combustion engine depending on a calculation result 11 by, for example, an operation control of the EGR valve 52 (an EGR control), a drive control of the fuel injection valve 20 (a fuel injection control) or the like.

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

First, an estimation value (a current EGR rate Regr) for the ratio of the EGR amount to the gas amount flowing into the cylinders 16 of the internal combustion engine 11 is drawn, based on the engine speed NE, the line suction amount GA and the suction pressure PM calculated. The current EGR rate can be determined based on the following considerations. It is possible to adjust the amount of gas entering the cylinders 16 of the internal combustion engine 11 is suctioned (a gas containing fresh air and EGR gas) to be determined on the basis of the intake pressure PM and the engine speed NE. In addition, the amount of air (the amount of fresh air), during a revolution of the crankshaft 12 in the cylinders 16 is suctioned, based on the line intake GA and the engine speed NE are determined. The amount (gas amount - fresh air amount) obtained by subtracting the fresh air amount from the gas amount may be obtained as the amount corresponding to the current EGR amount, and an EGR rate ((gas amount - fresh air amount) / gas amount) may be obtained Based on the amount described above and the amount of gas can be determined.

In addition, an EGR rate control target value (a target EGR rate Tegr) is set based on the engine rotational 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 operation control of the EGR valve 52 is performed based on the target EGR opening degree Tvr, the target EGR rate Tegr, and the current EGR rate Regr. More specifically, a provisional control that sets the target EGR opening degree Tvr as a preliminary control amount, and a feedback control based on the difference between the target EGR rate Tegr and the current EGR rate 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) with respect to a fuel injection amount for the operation of the internal combustion engine 11 is calculated on the basis of the amount of accelerator operation 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 period (a required injection duration Ttm) are calculated on the basis of the required injection amount TAU and the engine rotational speed NE. The valve opening drive control for each fuel injection valve 20 is performed on the basis of the required injection start Tst and the required injection duration Ttm. As a result, anytime fuel is in an amount that is an operating condition of the internal combustion engine 11 corresponds to the individual fuel injection valves 20 injected and then into the individual cylinders 16 of the internal combustion engine 11 delivered.

In the fuel injection control according to the present embodiment, when the engine rotational speed NE becomes during a lowering of the running speed of the vehicle 10 and the engine speed NE reaches a predetermined speed range because the operation of the accelerator operation member has been set (accelerator operation amount ACC = 0), control is performed to the fuel injection for driving the engine 11 temporarily stop (shear interruption control).

In the fuel injection control of this embodiment, three regions are set, namely, regions of low, middle, and high cetane numbers of the fuel (a lower cetane number region, a middle cetane number region, and an upper cetane number region), and the fuel injection control becomes one at a time for the various regions other implementation mode. For example, the required injection start Tst is included in the region a low cetane number earlier. More specifically, for each of the three cetane number regions, a relationship between the engine operating state determined based on the required injection amount TAU and the engine rotational speed NE and the required injection start Tst corresponding to the cetane number region is determined in advance based on results of various experiments and simulations, and the relationship will be in the electronic control unit 40 stored in the form of calculation maps (ML, MM, MH). On the basis of the respectively required injection quantity TAU and the engine speed NE, the required injection start Tst in the lower, middle and upper cetane number regions from the calculation maps ML, MM and MH is calculated.

When the fuel injection from the fuel injection valve 20 In some cases, due to initial individual differences, timing changes to the fuel injector may occur 20 or the like, an error may occur with respect to the execution time or the injection amount. This error is disadvantageous since it reduces the output torque of the internal combustion engine 11 changes. For this reason, in this embodiment, a correction processing is performed in which a waveform of a fuel injection rate and a fuel injection history in a detection period based on the pressure sensor 41 detected fuel pressure PQ is formed and a correction of the required injection start Tst and the required injection period Ttm be corrected based on the waveform in the detection period to the fuel injection from the fuel injection valve 20 in a suitable manner depending on the operating state of the internal combustion engine 11 perform. The correction process becomes for each cylinder 16 of the internal combustion engine 11 carried out separately.

The fuel pressure in the fuel injection valve 20 varies according to the opening / closing operations of the fuel injection valve 20 For example, it drops when the fuel injector 20 is opened, and rises when the fuel injector 20 subsequently closed. By monitoring the fluctuating waveform of fuel pressure in the fuel injector 20 during the execution of the fuel injection, therefore, the actual operating characteristics of the fuel injection valve 20 (For example, the actual fuel injection amount, the timing at which a valve opening operation starts, the time when a valve closing operation starts, and the like) are detected with high accuracy. By correcting the required injection start Tst and the required injection duration Ttm on the basis of the current operating characteristics of the fuel injection valve 20 Therefore, the fuel injection start and the fuel injection amount in a design, the operating condition of the internal combustion engine 11 corresponds, to be set exactly.

The correction process will be described in detail below.

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

3 FIG. 14 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, in each case, a timing at which the opening operation of the fuel injection valve is shown 20 (More precisely, an opening movement of the needle valve 22 ), a timing at which the fuel injection rate reaches its maximum value (a time Toe at which a maximum injection rate is reached), a timing at which the fuel injection rate starts to decrease (an injection rate reduction start) Tcs), and a point in time at which the closing operation of the fuel injection valve 20 (More precisely, a closing movement of the needle valve 22 ), (a valve closure actuation 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 20 calculated, and the average value is stored as the reference pressure Pbs. The reference pressure Pbs is used as the pressure corresponding to the fuel pressure in the fuel injection valve 20 when closing the valve corresponds.

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

Thereafter, a first-order differential value d (PQ) / dt based on a period for the fuel pressure PQ for a period in which the Fuel pressure PQ drops immediately after the start of fuel injection, calculated. A tangent L1 of a time-dependent waveform of the fuel pressure PQ at a point where the first-order differential value reaches its smallest value, that is, a downward slope of the fuel pressure PQ reaches its maximum value is determined. Further, an intersection A of the tangent L1 and the operating pressure Pac is calculated. A point of time corresponding to a point AA obtained by returning the point of intersection A to the past by the following delay of detection of the fuel pressure PQ is identified as the valve opening operation start Tos. The delay of the detection is a period that is a delay of a time point of change of the fuel pressure PQ with respect to a timing of change of the pressure in the nozzle chamber 25 of the fuel injection valve 20 (please refer 2 ), and is determined by the distance between the nozzle chamber 25 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 firstly decreases and then increases immediately after the start of the fuel injection. A tangent L2 of the time-dependent waveform of the fuel pressure PQ at a point where the first-order differential value reaches its maximum value, that is, at a point where a rise in the fuel pressure PQ reaches its maximum value is obtained, and further an intersection B becomes Tangent L2 and the operating pressure Pac calculated. A time corresponding to a point BB obtained by returning the cut point B to the past by a detection delay is identified as a valve closing operation end Tce.

Further, an intersection 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 C (ΔP [ΔP = Pac-PQ], which corresponds to a hypothetical pressure decrease) is determined. Moreover, a value obtained by multiplying the hypothetical pressure decrease ΔP by a factor G1 set on the basis of the required injection amount TAU is calculated as a 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 CC obtained by returning the point of intersection C to 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 timing 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 the time Tos is 0) and the maximum injection rate Rt is specified as the time Toe to which the maximum injection rate is reached.

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

Further, a time-dependent waveform of the fuel injection with a trapezoidal shape formed from the valve opening operation start Tos, the maximum injection rate reached time Toe, the injection closing decreasing start Tcs, the valve closing operation end tee, and the maximum injection rate Rt is taken as the fuel injection rate waveform Acquisition period used.

Now, with respect to 4 and 5 a process (correction process) for correcting various control target values in a fuel injection control based on the waveform in the detection period is described in detail.

4 Fig. 10 is a flowchart showing a specific procedure of the correction process. A series of processes illustrated in this flowchart shows the theoretical procedure in performing the correction processing, and an actual process is performed by the electronic control unit 40 performed as interruption process at predetermined intervals. 5 Fig. 10 shows an example of a relationship between a waveform in the detection period and the following waveform in a basic period.

As in 4 As illustrated above, in the correction process, first, as described above, a waveform is formed in a detection period during the execution of the fuel injection based on the fuel pressure PQ (step S101). Moreover, a basic value of the time-dependent waveform of the fuel injection rate (a waveform in a basic period) when fuel injection is performed 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 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 becomes in the electronic control unit 40 saved. In the process in step S102, the waveform in the basic period is always based on the relationship based on the current operating state of the internal combustion engine 11 set.

As in 5 1, a time-dependent trapezoidal waveform defined from a valve opening operation start Tosb, a maximum injection rate reached Toeb, an injection rate decreasing start Tcsb, a valve closing actuation end Tceb, and a maximum injection rate is set as a waveform in the basic period (a line, formed by alternate long and short dashes).

The waveform in the basic period is compared with the waveform in the detection period (solid line), and a correction quantity K1 and a correction quantity K2 are calculated. The correction quantity K1 serves to correct a control target value for the start of fuel injection (the required injection start Tst) on the basis of the comparison. The correction quantity K2 serves to correct a control target value for the execution time of the fuel injection (the required injection duration Ttm). 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 the correction quantity K1 (step S103 in FIG 4 ). In addition, the difference ΔTcs (ΔTcs = ΔTcsb-Tcs) between the injection rate reduction start Tcsb in the waveform in the basic period (FIG. 5 ) and the injection rate decreasing start Tcs are calculated in the waveform in the detection period and stored as the correction quantity K2 (step S104 in FIG 4 ).

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

In performing the fuel injection control, a value corrected by correcting the required injection start Tst using the correction quantity K1 (a value obtained by adding the correction amount K1 to the required injection start timing Tst in the present embodiment) is required to be final Injection start Tst 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 decreased. Therefore, in such a configuration, the start of the fuel injection is set with high accuracy so as to correspond to the operating state of the internal combustion engine 11 equivalent.

Moreover, a value obtained by correcting the required injection duration Ttm using the correction quantity K2 (in the present embodiment, a value obtained by adding the correction quantity K2 to the required injection duration Ttm) is calculated as the final required injection duration 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, in such a configuration, the timing at which the fuel injection rate starts to decrease is set with high accuracy so as to correspond to the operating state of the internal combustion engine 11 equivalent.

In the present embodiment, therefore, the required injection start Tst or the required injection duration Ttm is based on the difference between the current operating characteristics of the fuel injection valve 20 (Specifically, the waveform in the detection period) and the predetermined basic operating characteristics (more precisely, the waveform in the basic period) corrected. Therefore, the difference between the current operating characteristic of the fuel injection valve 20 and the basic operation index (the operating characteristic number of the fuel injection valve with a standard characteristic number) are reduced. As a result, the injection start and the injection amount become out of each fuel injection valve 20 during the fuel injection, respectively according to the operating state of the internal combustion engine 11 set appropriately.

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

In the index value detection process, an execution condition is set which includes a condition that the thrust interruption control is performed ([Condition 1] described below). Upon fulfillment of the implementation requirement, a Fuel injection into the combustion engine 11 with a predetermined small amount FQ (eg, a few cubic millimeters), and further, an index value of the output torque of the internal combustion engine 11 that is generated due to the execution of the fuel injection, (an amount of a rotational speed fluctuation ΣΔNE, described below) 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 is the value detected for the amount of speed fluctuation ΣΔNE.

The higher the cetane number of the fuel is that of the internal combustion engine 11 is to be delivered, the easier the fuel is ignited and the more complete the fuel is 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 detected.

An operation of performing the index value detection process will be described in detail below.

6 Fig. 10 is a flowchart showing a specific procedure of the index value detection process. A series of processes shown in this flowchart show the theoretical process of performing the index value detection process, and an actual process is performed by the electronic control unit 40 performed as an interrupt process for each given cycle.

As in 6 1, it is first determined in the process whether or not a performance requirement is met (step S201). In this case, it is determined that the implementation requirement is met if Condition 1 to Condition 3, which are described below, are all met.

[Requirement 1] The overrun control is performed.

[Requirement 2] The coupling mechanism 13 is in the operating condition in which the clutch mechanism is the crankshaft 12 and the manual transmission 14 separates each other. More specifically, the clutch operating member is being operated.

[Requirement 3] The correction process is performed properly. More specifically, none of the correction quantities K1, K2 calculated in the correction process is an upper limit or a lower limit.

If the execution requirement is not satisfied (step S201: NO), the following process, i. H. a process for detecting the index value of the cetane number of the fuel, not performed, but the present process is temporarily suspended.

Thereafter, if the present process has been repeatedly performed until the execution requirement is satisfied (step S201: YES), the process of detecting the index value starts the cetane number of the fuel.

More specifically, first, a control target value for a given fuel injection start (target injection start TQst) and a control target value for the fuel injection period (target injection duration TQtm) are determined by using the correction quantity K1, K2 included in the in 4 and 5 corrected correction process is corrected (step S202 in FIG 6 ). Specifically, a value obtained by adding the correction quantity K1 to the target injection start TQst is set as a new target injection start TQst, and a value obtained by adding the correction quantity K2 to the target injection duration TQtm is set as a new target injection timing TQst. Injection duration TQtm set.

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

Thereafter, the amount of speed fluctuation ΣΔNE becomes an index value of the output torque of the internal combustion engine 11 by injecting the predetermined amount of fuel FQ is generated, 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 7 is illustrated, in the apparatus according to the present embodiment, the engine speed is regularly detected at predetermined times, and the difference .DELTA.NE (.DELTA.NE = NE - NEi) between the engine speed NE and an engine speed NEi, which has been detected in the past (one of the n th in the present embodiment, third in the present embodiment) is calculated at each detection. An integrated value for a variation of the difference ΔNE with the execution of the fuel injection (which is a value corresponding to an area extending from a diagonal line in FIG 7 is calculated), and the integrated value is further stored as a range of the rotational speed fluctuation ΣΔNE. Since changes in the engine speed NE or the difference ΔNE in 7 In order to better understand a method for calculating the amount of speed fluctuation ΣΔNE, they are slightly different from actual changes.

In the present embodiment, basically, one of the lower, middle and upper cetane number regions is specified on the basis of the amount of speed fluctuation ΣΔNE detected in the first index value detection process, and the specified region is further stored in the electronic control unit 40 saved. 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 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.

If the cetane number of the fuel, the internal combustion engine 11 is to be supplied, the ignition delay is prolonged, so that the combustion state of the fuel tends to deteriorate. In idling mode immediately after the initiation of the start of the internal combustion engine 11 In addition, the amount of fuel that is in the cylinder 16 to be injected, small, and the temperature in the cylinders 16 is low. For this reason, the combustion state of the fuel tends to deteriorate. In the apparatus according to the present embodiment, therefore, it becomes 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 misfiring can easily occur.

As far as this is concerned, 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 target EGR rate Tegr is set to 0 in idle mode and the EGR amount of the EGR device 50 is set to 0. When the idling operation immediately after the initiation of the start of the internal combustion engine 11 in a situation where the lower cetane number region is stored, that is, when the combustion state of the fuel tends to be more susceptible to a regulation error of the EGR amount, and the combustion state of the fuel is likely to be unstable, as a result, the combustion state of the fuel can be increased the cylinders 16 of the internal combustion engine 11 be improved according to the interruption of EGR gas recirculation. Therefore, the occurrence of misfires can be suppressed.

In order to improve the combustion state of the fuel in idling operation in the particular situation, except for setting the amount of EGR in the idle mode to 0, the EGR amount can be reduced as compared with a non-specific situation. Because of the volume of EGR pipe 51 or a portion of a connection portion of the EGR passage 51 in the intake pipe 17 to the cylinders 16 of the internal combustion engine 11 in the EGR device 50 For example, the occurrence of a delay in a change in the EGR amount with respect to a change in the opening of the EGR valve 52 can not be avoided. For this reason, the response or the stability of the change in the EGR amount with respect to the change of the opening of the EGR valve 52 bad, and it is difficult to control the amount of EGR through the EGR device 50 fine to settle.

As a result, it is obvious that it is in the regulation of the amount of EGR by the EGR device 50 can easily lead to regulatory errors. If the EGR amount is excessively increased due to the regulatory error, the combustion state of the fuel may become worse. In addition, if the EGR amount is reduced too much due to the regulatory error, the combustion temperature of the fuel may become high in the cylinders 16 increase, resulting in an increase of nitrogen oxide (NOx) in the exhaust gas.

As to this, in the present embodiment, in a particular situation, i. H. If the combustion state of the fuel tends to be greatly affected by the EGR amount regulation error and the combustion state of the fuel is likely to be unstable, the EGR amount regulation error itself will be eliminated. Therefore, the influence of the regulatory error on the combustion state of the fuel can be eliminated.

As described above, the EGR amount in the idle mode 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 misfires can be suppressed. If the EGR amount is simply set to 0, however, the combustion temperature of the fuel in the cylinders increases 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 operation is set to a later time compared with the non-specific situation, which corresponds to the setting of the EGR amount in the idle mode to 0 in the particular situation. The nonspecific 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 initiation of the start of the internal combustion engine 11 expires.

By setting a later time as the fuel injection start, the ignition timing of the fuel in the cylinders becomes 16 of the internal combustion engine 11 delayed. Therefore, accordingly, the combustion temperature of the fuel is lowered, so that the amount of NOx is reduced. In the present embodiment, a fuel injection start (more specifically, the required start of injection Tst) to which a suppression of a deterioration of a combustion state and a 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 combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 is adjusted by a setting in which the fuel injection start is adjusted, compared to the setting which is performed by regulating the EGR amount, in the idle mode in the particular situation with greater accuracy. According to the present embodiment, therefore, it is possible to control the combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 to properly adjust when using low cetane fuel. Therefore, suppression of occurrence of misfires can be made compatible with NOx discharge amount control.

The following is a detailed description of a process for setting the EGR amount to 0 in the particular situation and a process for delaying fuel injection start.

First, the process for setting the EGR amount to 0 in idle mode in the particular situation with reference to 8th described.

8th FIG. 10 shows a flow in the execution of a process related to EGR control (EGR control process). A process flow that is shown in the flowchart of 8th is shown by the electronic control unit 40 performed as an interrupt process for each given cycle.

As in 8th 1, it is first determined in the process whether or not both condition 4 and condition 5 are satisfied (step S301).

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

[Condition 5] It is an execution period from the initiation of the start of the internal combustion engine 11 until the start of the operation of the accelerator operation member (an operation for increasing the accelerator operation amount ACC to greater than 0). More specifically, the accelerator operation amount ACC is continuously maintained in the state 0 after the operation switch 48 has been actuated to the drive operation of the internal combustion engine 11 to start.

If both [Condition 4] and [Condition 5] are satisfied (Step S301: YES), the combustion state of the fuel tends to be highly susceptible to the EGR amount regulation error, and the combustion state of the fuel is likely to be unstable during this time. 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, if the requirement 4 or the requirement 5 is not met (step S301: NO), a normal control (more precisely, the operation control of the EGR valve 52 that corresponds to the target EGR rate that is set based on the engine speed NE and the required injection amount TAU) as the EGR control process (step S303). More specifically, if the requirement 4 is not met, the normal control as the EGR control process is made on the assumption that there is little possibility of excessive deterioration of the fuel combustion state because at that time the middle cetane number region or the upper cetane number region is specified is stored in the electronic control device. Further, if the requirement 5 is not satisfied, the normal control is performed as the EGR control process on the assumption that there is little possibility of excessive deterioration of the fuel combustion state because the temperature in the cylinders 16 of the internal combustion engine 11 increases with a continuation of the engine operation after starting.

Now, a process for delaying the fuel injection start (an injection start delay process) will be explained with reference to FIG 9 described.

9 Fig. 10 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, in the process, first, it is determined whether or not the EGR opening degree VR is equal to or smaller than a predetermined opening degree (for example, an opening degree slightly larger than an opening degree in valve closing) (step S401). In the process, it is determined whether or not the engine rotational speed NE is equal to or lower than a predetermined rotational speed (for example, a rotational speed [1300 rpm] corresponding to an upper limit for the engine rotational speed NE in idle operation) (step S402), and further determines whether or not the required injection amount TAU is equal to or smaller than a predetermined amount (for example, the amount corresponding to an upper limit value for the fuel injection amount in the idle 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 this time. When the engine rotational speed NE is equal to or smaller than the predetermined rotational speed (step S402: YES) and when the required injection amount TAU is equal to or smaller than the predetermined amount (step S403: YES), it is determined that the internal combustion engine 11 has been brought into the idle operating state. Accordingly, if all the determinations in steps S401 to S404 are affirmative, it is determined that both the condition 4 and the condition 5 are satisfied in the EGR control process (see 8th ), and the EGR amount is set to 0. In other words, at this time, the lower cetane number region is stored, and the execution period from the initiation of the start of the internal combustion engine 11 until the start of the manipulation of the accelerator actuator is there. Therefore, it is determined that the EGR amount is set to 0 to improve the combustion state of the fuel and to suppress misfires.

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

In the present embodiment, as a calculation map used for setting the required injection start Tst, a calculation map is set up that corresponds to a situation where the EGR amount in the idle mode is set to 0 in the particular situation, that is, a calculation map MLF in addition to the above-described calculation maps ML, MM and MH, in which a comparatively later time is set. Specifically, a relationship between the engine operating condition determined by the required injection amount TAU and the engine rotational speed NE and the required injection start timing Tst corresponding to the situation where the EGR amount is set to 0 in the idling condition in the particular situation is made to advance from the results of various experiments or simulations, and further the relationship becomes the calculation map MLF in the electronic control unit 40 saved.

More specifically, in the process of step S405, the calculation map MLF is selected from the calculation maps. In the subsequent fuel injection control, the required injection start Tst is set on the basis of the required injection amount TAU and the engine speed NE based on the calculation 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 time is set as the fuel injection start is made on the assumption that the EGR amount is not set to 0 at this time ( Step S406). More specifically, in the normal control, any of the calculation maps corresponding to the cetane number regions stored at that time, ie, the calculation maps ML, MM, and MH are selected, and the required injection start Tst is then determined based on the required injection amount TAU and the engine rotational speed NE adjusted on the basis of the selected calculation map. In addition, when the engine rotational speed NE is higher than a predetermined rotational speed (step S402: NO), or when the required injection amount TAU is greater than a predetermined amount (step S403: NO), the normal control is performed on the assumption that the engine is running 11 is not set to the idle state (step S406).

Thus, 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 later timing as the fuel injection start (the process of step S405 in FIG 9 ) only for a period of execution from the initiation of the start of the internal combustion engine 11 executed until the start of the manipulation of the accelerator actuator. Because of this, it is only when the temperature of the cylinder 16 of the internal combustion engine 11 is low immediately after the initiation of the start, ie, only for a period of time in which the combustion state of the fuel in the cylinders 16 is unstable, it is possible to set a process of implementing the setting of the combustion state of the fuel (the process of setting the EGR amount to 0 and the process of setting a later time point as the fuel injection start) with high accuracy.

On the other hand, if the external pressure is equal to or higher than the decision pressure (step S404: NO), the normal control is performed (step S406). When the external pressure is low, the density of the air is low, so that the amount of oxygen contained in the intake air is small. For this reason, the combustion state of the fuel in the cylinders 16 of the internal combustion engine tends to deteriorate so that misfiring can easily occur. According to the present embodiment, when misfire can easily occur due to the low external pressure, the calculation map MLF can be selected, thereby setting the required injection start Tst to a later time, that is, changing the required injection start Tst to one side. Where it is caused that the combustion state of the fuel becomes worse, can be prevented. Therefore, the occurrence of misfires can be reliably suppressed. When the external pressure is higher than the decision pressure (step S404: YES), that is, misfires can be made comparatively difficult, based on the calculation map MLF, a later time is set as the required injection start Tst. Therefore, the NOx discharge amount can be suitably controlled. In the present embodiment, a decision pressure with which the occurrence of idling misfires in the particular situation can be reliably suppressed is obtained in advance based on results of various experiments and simulations and in the electronic memory unit 40 saved.

The execution modes of the process for setting the EGR amount at idle in the particular situation to zero and the process for delaying the fuel injection start 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 apparatus according to the present embodiment, and lines formed alternately of 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 Amount is not set to 0 and the fuel injection start is not delayed. It also shows a line in 10 which is alternately formed by a long stroke and two short dashes, changes in the NOx discharge amount in the case where the EGR amount is set to 0 and the fuel injection start is not delayed.

In the example of 10 becomes the operation switch 48 at a time t11 set to ON, allowing starting of the internal combustion engine 11 is initiated. At this time, the lower cetane number region is stored and the accelerator operation member is not manipulated (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 this time, moreover, as compared with a time excluding the execution period immediately after the initiation of the engine start MLF, based on the calculation map, a time later than the required injection start Tst corresponding to a part shown in FIG a white arrow is displayed.

At this time, in the apparatus according to the comparative example shown in the lines, which is shown in FIG 10 are alternately formed by a long stroke and a short stroke, the NOx discharge amount is controlled so as to be quite small, but deterioration of the combustion state of the fuel in the cylinders becomes 16 causes misfiring or smoke development. In contrast, in the device shown in the line, the in 10 is formed alternately by a long dash and two short dashes, the combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 sufficiently improved to prevent occurrence of misfire or smoke development. However, as the combustion temperature of the fuel greatly increases, the NOx discharge amount also increases considerably.

In the apparatus according to the present embodiment, on the other hand, the EGR amount is set to 0, and as fuel injection start, a later start is set at times t11 to t12. Therefore, it can be prevented that the NOx discharge amount becomes considerably larger, as in the device shown in the line formed alternately by a long stroke and two short dashes, and it can be prevented from causing misfires or Smoke comes, as in the device according to the comparative example, which is formed alternately by a long stroke and a short stroke. Thus, according to the present embodiment, the combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 be adjusted properly when using the low cetane fuel. As a result, the suppression of the occurrence of misfire and the control of the NOx discharge amount can be made to be compatible with each other.

When the manipulation of the accelerator operation member is started at time t12, in the present example, the execution of the process for setting the EGR amount to 0 and the process for delaying the fuel injection start is subsequently stopped. At this time, the operation control of the EGR valve becomes 52 is performed depending on the target EGR rate, which is set based on the engine speed NE and the required injection amount TAU, and the drive control of the fuel injection valve 20 is performed depending on the required fuel injection start Tst, which is set based on one of the calculation maps ML, MM, and MH based on the amount of 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 which will be described below can be obtained.

• (1) For the implementation period immediately after the initiation of the starting of the internal combustion engine 11 and in the particular situation where the lower cetane number region is stored, the EGR amount in the idle mode is set to 0, and the required ignition timing Tst in the idle mode is rearwardly compared with a non-specific situation. Therefore, the combustion state of the fuel in the cylinders 16 of the internal combustion engine 11 be properly adjusted when using the low cetane fuel, thereby causing the misfire suppression and NOx discharge control to be compatible with each other.
• (2) The EGR amount in the idle mode in the particular situation is set to 0. Therefore, the influence of the EGR amount regulating error on the combustion state of the fuel can be eliminated, whereby the combustion state of the fuel is adjusted with more accuracy.
• (3) On the assumption that the external pressure is equal to or higher than the decision pressure, the process of setting an earlier time as the fuel injection start (the process of step S405 in FIG 9 ) carried out. Therefore, the change of the required injection start Tst to the side where deterioration of the combustion state of the fuel is caused when the external pressure is low and misfire can easily occur can be prevented. As a result, the occurrence of misfire can be easily prevented. In addition, if it is comparatively difficult to cause the occurrence of misfires due to a high external pressure, the required injection start is allowed to be rearwardly adjusted. Therefore, the NOx discharge amount can be appropriately suppressed.
• (4) The process of setting the EGR amount to 0 (the process of step S302 in FIG 8th ) and the fuel injection start delay process (the process of step S405 in FIG 9 ) are only for the execution period after initiation of the start of the internal combustion engine 11 performed until the start of manipulation of the accelerator actuator. Therefore, it is possible to perform the process for implementing the setting of the combustion state of the fuel with high precision only in a period in which the combustion state of the fuel in the cylinder 16 of the internal combustion engine 11 probably unstable.

The embodiment described above may 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 such a device, it is also possible to have the required ignition timing Tst in the idling operation in comparison with the non-specific situation in the execution period immediately after initiation of the start of the internal combustion engine 11 and in the particular situation where the lower cetane number region is stored, to rearrange.

The adjustment of the required injection start Tst may be performed by using an arithmetic expression as well as the calculation map.

The adjustment 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 injection start point Tst is set from the calculation map ML based on the engine speed NE and the required injection amount TAU, and further, a retard correction amount is calculated on the basis of the engine speed NE and the required injection amount TAU. A value obtained by correcting the required injection start Tst with the retard correction amount is set to be a final required injection start Tst.

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

In the particular situation, besides setting the EGR amount to 0, it is also possible to open the EGR gas by opening the EGR valve slightly 52 due to idling in a small amount. In short, it is preferable to reduce the EGR amount in the idling operation in the particular situation as compared to the EGR amount in the non-particular situation. By this device, it is also possible to reduce the regulation error of the EGR amount corresponding to a decrease in the absolute amount of the EGR amount in idle mode in the particular situation, ie, when the combustion state of the fuel is greatly affected by the EGR amount regulation error and Combustion state of the fuel is likely to be unstable to reduce. Therefore, the influence of the regulatory 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 start of the manipulation of the accelerator operation member, the process for setting the EGR amount becomes 0 (the process of step S302 in FIG 8th ) and the process of setting a later timing as the fuel injection start (the process of step S405 in FIG 9 ). Instead, it is also possible to perform 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 period includes a certain time (for example, several seconds to several tens of seconds), a period of time required until the integrated value of the fuel injection amount reaches a predetermined value, a period until the integrated value of the intake amount reaches a predetermined value , and the same. In short, for an execution period that is necessary until the temperature of the cylinders 16 of the internal combustion engine 11 has fully increased, so that the combustion state of the fuel is improved, preferably, the process for setting the EGR amount to 0 and the process for setting a later time as a fuel injection start executed.

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

By appropriately changing the configuration, it is also possible for the control apparatus according to the above-described embodiment to be an apparatus for determining one of two regions obtained by dividing an index value of a cetane number of the fuel (the amount of speed fluctuation ΣΔNE) or a device for Determine one of four or more regions.

By appropriately changing the configuration, it is also possible to apply the control apparatus according to the above-described embodiment to an apparatus which determines the amount of speed fluctuation ΣΔNE generated in the electronic control apparatus 40 is stored as a value corresponding to the cetane number of the fuel to the internal combustion engine 11 to be delivered ( more precisely, a cetane number index value) without specifying the cetane number region based on the amount of speed fluctuation ΣΔNE. When the amount of 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 idle mode special situation to 0 and the process for setting a later time as the fuel injection start to be performed.

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

A mode for mounting the pressure sensor 41 optional except a mode for direct attachment of the pressure sensor 41 at the fuel injection valve 20 be changed, as long as it is possible, a pressure for an index of the fuel pressure in the fuel injection valve 20 (more precisely in the nozzle chamber 25 ), that is, adequately detecting the change of a fuel pressure with a variation of the fuel pressure. Specifically, the pressure sensor on the branch line 31a or the common pressure line 34 be attached.

Instead of the fuel injection valve 20 the type used by the piezoelectric actuator 29 is controlled, a fuel injection valve of a kind which is driven by an electromagnetic actuator, which includes, for example, a magnetic coil or the like may also be used.

The control apparatus according to the above-described embodiment may except for the vehicle 10 that with the clutch mechanism 13 and the manual transmission 14 is also applied to a vehicle that is 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 performed when, for example, the requirement 1 and the requirement 3 are fulfilled. 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 requirement 6 in that the lock-up clutch is not brought into an engaged state, is reset and that the requirement 6 is satisfied.

The present invention is not limited to the apparatus for performing the fuel injection for determining the cetane number of the fuel that is the internal combustion engine 11 may be applied to a device for carrying out the method for determining the cetane number of the fuel. The device may include, for example, the following device. In other words, first, the pressure in the cylinder of the internal combustion engine (a cylinder pressure) is detected by a cylinder pressure sensor in the execution of the 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 further, an ignition delay time is calculated based on the timing. Then, a cetane number index value is calculated on the basis of the thus calculated ignition delay time.

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

DESCRIPTION OF THE REFERENCE SIGNS

• 10 ... vehicle, 11 ... combustion engine, 12 ... crankshaft, 13 ... coupling mechanism, 14 ... manual gearbox, 15 ... wheel, 16 ... cylinders, 17 ... suction line, 18 ... Piston, 19 ... exhaust pipe, 20 ... fuel injection valve, 21 ... Casing, 22 ... needle valve, 23 ... injection opening, 24 ... Feather, 25 ... nozzle chamber, 26 ... pressure chamber, 27 ... inlet pipe, 28 ... communication line, 29 ... piezoelectric actuator, 29a ... valve element, 30 ... derivation, 31a ... branch, 31b ... supply line, 32 ... fuel tank, 33 ... fuel pump, 34 ... common pressure line, 35 ... return, 40 ... electronic control unit, 41 ... pressure sensor, 42 ... crank sensor, 43 ... accelerator sensor, 44 ... external pressure sensor, 45 ... intake sensor, 46 ... suction pressure sensor, 47 ... opening sensor, 48 ... operating switch, 50 ... EGR device, 51 ... EGR line, 52 ... AGR valve.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2007-285195 [0006]

Claims (4)

Control device for an internal combustion engine, the control device comprising: an EGR device for returning exhaust gas by returning a part of the exhaust gas flowing in an exhaust pipe of the internal combustion engine into an intake pipe; a determination unit for determining a cetane number of fuel to be supplied to the internal combustion engine; and a control unit, wherein, when the cetane number determined by the determination unit is low during an execution period immediately after initiation of the engine start, the control unit decreases an EGR amount by the EGR device in an idle operation and the fuel injection period moved backwards compared to other cases. The control device for an internal combustion engine according to claim 1, wherein the controller sets the EGR amount to zero. A control device for an internal combustion engine according to claim 1 or 2, wherein the control unit performs the rearward adjustment of the fuel injection start on the assumption that an external pressure is equal to or higher than a predetermined decision pressure. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the execution period is a period from the initiation of the start of the internal combustion engine to the start of the manipulation of an accelerator operation member.

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