DE10006640B4 - Control device for an internal combustion engine with direct injection - Google Patents

Abstract

In a direct injection engine, if knock occurs in a cylinder at that time when the engine is in a compression stroke injection mode, fuel is injected into another cylinder on the intake stroke before fuel is injected into that cylinder on the compression stroke, so that the The occurrence of knocking can be suppressed by lowering the temperature in the cylinder. This arrangement makes it possible to obtain the best performance of the internal combustion engine in the normal operating condition by suppressing knocking which occurs in a specific operating condition.

Description

The The present invention relates to fuel injection control for an internal combustion engine Direct injection.

5 shows schematically the structure of such a known internal combustion engine, which is provided with a direct injection system, and the arrangement of a control or regulating device.

In 5 has an internal combustion engine 1 with direct injection for motor vehicles an air flow sensor 2 for measuring the intake air amount sucked by the internal combustion engine, a throttle valve three operated in cooperation with an accelerator pedal, which is normally operated by a driver of the motor vehicle to adjust the amount of intake air sucked by the internal combustion engine, a throttle position sensor 4 for detecting the position of the throttle valve three , a crank angle sensor 5 for detecting the engine speed and the position of the crankshaft, a water temperature sensor 6 for detecting the cooling water temperature as a device for detecting the warm-up state of the internal combustion engine, an O ₂ sensor 7 for detecting the oxygen concentration in the exhaust gas discharged from the internal combustion engine, a controller 8th , a spark plug 9 , an air bypass valve 10 , an injector 11 for supplying fuel to a cylinder, a cylinder identification sensor 14 mounted on a crankshaft for identifying the cylinder in which combustion is taking place and a knock sensor 15 for detecting conditions in which knocking occurs in the internal combustion engine.

It It should be noted that in addition to Regulation of the fuel quantity to be injected on the basis the intake air amount, the control also be performed on the basis of the intake air pressure can, the throttle angle, the volumetric efficiency, or the feed efficiency.

The control or regulating device 8th is a controller (ECU) for combusting fuel in the internal combustion engine at a desired air / fuel ratio by determining the operating state of the internal combustion engine on the basis of the signals from the air flow sensor 2 , the throttle angle sensor 4 and the crank angle sensor 5 be detected, and to calculate various control or control variables according to the operating state.

The air bypass valve 10 controls the engine speed at idle when the throttle is fully closed by controlling the amount of air flowing to the throttle three bypasses.

The injector 11 is operated in response to a default electrical signal provided by an injector driver 13 is transmitted.

An EGR valve 12 is a valve for controlling the amount of recirculated exhaust gases by returning the exhaust gases from the internal combustion engine to the combustion chambers and recombining them to reduce the amount of NOx.

It should be noted that the spark plug 9 , the air bypass valve 10 , the EGR valve 12 and the injector driver 13 all of the control or regulating device 8th be controlled and that the injector 11 with the help of the injector driver 13 is operated.

Internal combustion engines, those with such a control system for internal combustion engines provided with direct injection, as described above was found to be beneficial by the following four effects.

(1) Reduction of exhaust gases

at usual Systems in which fuel in a section outside A cylinder is injected as a result of the fact that a certain proportion of the injected fuel on the intake valve and the intake valve guides deposits before being pulled into a cylinder that has been deposited Be considered fuel especially when an internal combustion engine at low temperatures is started, in which the evaporation of the fuel is difficult and when the internal combustion engine is operated in a transient state, in which relatively fast reactions to fluctuations in the fuel supplied required are.

in the Contrast this Internal combustion engines with direct injection the amounts of discharged Reduce HC and CO as lean air / fuel ratio is chosen can, without any delays considered during fuel transport Need to become.

(2) Improvement of fuel consumption

When fuel is injected into a cylinder, a combustion state in which the fuel corresponding to the ignition timing immediately before ignition of the fuel is injected, so that a combustion state is generated in which the from a combustible force substance formed fuel mixture is distributed unevenly in the vicinity of a spark plug at the ignition. This allows stratified combustion. Thereby, an apparent air / fuel ratio with respect to the supplied air amount and the supplied amount of fuel supplied to the cylinder can be made extremely lean. In addition, the introduction of large amounts of recirculated exhaust gases does not adversely affect combustion due to the achievement of stratified combustion. Therefore, fuel consumption can be reduced and pumping losses can be reduced.

(3) Improved output power of internal combustion engines

There In a stratified combustion, the fuel mixture near the spark plug accumulates, can reduce the generation of a knocking gas whereby anti-knock properties can be improved, and also the compression ratio the internal combustion engine increases can be. As the fuel in the cylinder is evaporated, it will about that In addition, the density of the intake air by heat extraction from the intake air increased in the cylinder, whereby the volumetric efficiency increases. Therefore, the output power the internal combustion engine can be improved.

(4) Improved driving behavior

There Fuel is injected directly into the cylinder, the delay is between at that time, when the fuel is supplied and burned until at that time, at which an output by the combustion of the fuel is generated, shorter as with conventional Internal combustion engine, which makes an internal combustion engine with excellent Reaction can be achieved.

For conventional Internal combustion engines with direct injection, in which the above described effects occur, the JP 04-183 951 A describes Procedures for the knock suppression.

at in this publication knocked suggestion is suppressed by the fact that the ignition at a delayed ignition timing carried out and fuel is injected at an anticipated spark timing during the Compression strokes when knocking has occurred.

Beat is due to spontaneous ignition and burning the final one Gas mixture in a cylinder caused at an ignition, which is from the actual ignition differs at which the ignition is performed with the help of the spark plug.

Therefore Tapping can be hard to occur if only in the fuel Near the Spark plug available is like fuel injection during the compression stroke the case is. However, there is a possibility that the Fuel ignited spontaneously, and knocking occurs under special conditions which the compression ratio the internal combustion engine is high, the ignition point is presented, the temperature of the intake air itself is high, a slightly evaporating fuel is used and the fuel is not layered perfectly.

at the direct injection control system is a mode (lean mode) present, in which fuel as described in the above Compression stroke is delivered to the exhaust gases and fuel consumption to improve, as well as a usual Mode exists in which the operation is carried out in such a way that fuel during the Intake stroke is delivered, and he is in a uniformly mixed, normal condition is burned.

The above-described compression stroke injection mode (lean mode) has a significant impact on reduced fuel consumption, as described above under (2), and has the Advantage on that the Occurrence of knocking is unlikely, as described in (3) has been. Therefore, you can the compression ratio and the ignition timing an internal combustion engine are adjusted so that the improvement the output power of the internal combustion engine has priority.

If one considers, however, that a vehicle indeed is driven under special conditions, for example at a very light weight evaporating fuel in relatively high temperature environments and high drought, that's how it works do not avoid that compression ratio and the ignition timing be set so that in to a certain extent the Fuel consumption and the output of the internal combustion engine impaired become.

Since the characteristics of an internal combustion engine are adjusted so that it can cope even with such conditions in which most users never get, this leads to the fact that under normal conditions the fuel consumption of the vehicle is deteriorated to some extent. This is because if the fuel injection timing or the ignition timing or both are changed substantially, there is a high possibility that the Ver combustion behavior is adversely affected, and when knocking occurs at this time, the ignition timing can not be delayed as in the conventional knock control, since the combustion in the compression stroke injection mode is performed by a subtle timing for the fuel injection and the ignition.

6 shows the operation of a conventional internal combustion engine with direct injection, which is operated with a control or regulating device.

6 shows successively the operating characteristics from the top in the diagram, such as an output signal SGC from the cylinder identification sensor 14 , an output signal SGT from the crank angle sensor 5 , the state of the combustion stroke of each cylinder, which is detected on the basis of the output signals SGC and SGT, the injection timing of each injector, and the timing at which knocking occurs. It should be noted that 6 moreover, shows an output signal from each sensor and the combustion process that changes from left to right in the figure over time.

If like in 6 As shown in the conventional controller, knocking occurs at a time T9 during combustion in a third cylinder (# 3), the controller reads an output signal from a knock sensor at a time T4 (see the output of the crank angle sensor). However, since a compression stroke injection is performed, the amount of fuel injected from the injector of a fourth cylinder (# 4) and the ignition timing are controlled at a time T14 without performing a knocking control.

Therefore Knocking occurs continuously in the fourth cylinder (# 4) itself at a time T10 on. Thereafter, knocking occurs continuously itself at times T11 and T12, since no knock control is performed, and the control variables are related do not change on injected fuel and ignition timing.

Furthermore, the describes EP 0 849 459 A1 an internal combustion engine to avoid knocking as the compression ratio is increased. A control device 16 is provided to the fuel injector 21 to drive and control so that fuel is already injected into the intake stroke with an amount, so that the fuel is not ignited itself. In the stratified charge mode, the combustion is performed such that after injecting the fuel during the compression stroke, the injected fuel does not have enough time during the compression stroke to cause a knocking reaction.

Furthermore, the disclosed DE 197 49 154 A1 a control device for a cylinder-injection internal combustion engine which detects deteriorated combustion efficiency. The control device has an electronic control unit 20 for driving the fuel injection valve 8th and the ignition coil unit 9 in accordance with the operating state of the internal combustion engine. The control device further includes a combustion state determining device for determining the combustion state of the internal combustion engine and a combustion efficiency recovery device for restoring the combustion efficiency to the internal combustion engine, which acts when the combustion state has deteriorated.

The The aim of the present invention is, therefore, in sufficient Extent that Potential of the internal combustion engine with direct injection with the above training even when knocking occurs be used in such a way that the output power is given priority and thereby the fuel consumption is reduced.

A Control or regulating device for a direct injection internal combustion engine according to the present invention Invention is characterized by the features of claim 1.

at an embodiment is the amount of fuel to be injected into the cylinder which is in the intake stroke after knocking has occurred preferably adjusted so that a Air / fuel ratio is achieved, wherein the fuel in the cylinder is not ignited.

at a further embodiment is the amount of fuel that is injected into the cylinder should, which is in the intake stroke, after the occurrence of knocking, preferably adjusted so that the Output torque caused by the combustion of an amount of fuel is generated, which is the sum of the above-mentioned amount of fuel and that amount of fuel entering the cylinder in the compression stroke is adjusted after the intake stroke, approximately equal to that output torque which is generated based on the amount of fuel that is injected into the compression stroke when knocking does not occur.

The The invention will be described below with reference to drawings explained in more detail, from which further benefits and features emerge. It shows:

1 the operation of an internal combustion engine with direct injection, of a STEU control device is controlled according to the present invention;

2 FIG. 14 is a flowchart showing the processing performed by the controller at a time point TDC (the time point at which a signal SGT decreases). FIG 1 ;

three a flow chart showing the processing performed by the controller at a time 70 ° B in 1 shows;

4 Fig. 10 is a flowchart showing the manner of the control amount calculation processing performed by the controller every predetermined time;

5 a schematic view of the configuration of a conventional internal combustion engine, which is provided with a direct injection system and a control or regulating device; and

6 the operation of a conventional direct injection engine, which is controlled by a conventional control or regulating device.

EMBODIMENT 1

1 Fig. 11 shows the operation of a direct injection engine controlled by a controller (hereinafter referred to as a controller) according to the present invention. 1 FIG. 12 shows an output signal from an angle sensor and a combustion process that changes from left to right in the figure over time.

The internal combustion engine according to Embodiment 1 is similar to that in FIG 5 Conventional internal combustion engine shown, and the control device of the direct injection engine according to the present invention is characterized by the manner of processing, by a control device 8th is carried out. In the following description, the same reference numerals as in FIG 5 used to designate the same components.

Furthermore, an air flow sensor is used 2 As the intake air quantity detector device, a throttle angle sensor is used 4 As the throttle angle detecting device, a crank angle sensor is used 5 As a crank angle detecting device, a cylinder identification sensor is used 14 as a cylinder identification device, and serves a knock sensor 15 as a knock detector device.

It It should be noted that the amount of fuel to be injected based on the intake air pressure, the throttle angle, the volumetric efficiency or the feed efficiency can be controlled via the Regulation based on intake air amount.

Specifically, the level of an SGC signal is successively detected (H (high), L (low), H, H, L, L, L, and H) every time the level of the signal SGT changes (time points T1 to T8). Then, the detected signal levels obtained each time the signal SGT decreases (TDC) and rises, respectively (70 ° B in FIG 1 ) are grouped in pairs (H, L), (H, H), (L, L) and (L, H) identifying four types of cylinders to thereby identify cylinders to which fuel is supplied (cylinders in the compression stroke and in the intake stroke), and the injector for the respective cylinder is regulated according to the time.

According to 1 In the control device according to the present invention, when knocking occurs during combustion in the third cylinder (# 3) at time T21, intake stroke injection is added after the controller 8th has read the signal output from the knock sensor. However, since a compression stroke is performed in the fourth cylinder (# 4), the compression stroke injection continues until a timing T22, and concurrently, intake stroke injection control is performed in the second cylinder (# 2) in which the intake stroke is currently taking place.

This leads to, that too a time 23 knocking occurs because at time 21 only one Compression stroke injection in the fourth cylinder (# 4) is performed. However, since the intake / compression stroke injection during the next Combustion in the second cylinder (# 2) and the subsequent cylinders carried out is knocking is suppressed at the times T25 and 26.

Now, the operation of the direct injection type internal combustion engine according to the present invention which is controlled by the controller will be described with reference to FIGS 2 to 4 described.

2 FIG. 14 is a flowchart showing the manner of processing performed by the controller at a time TDC (time at which the signal SGT decreases) in FIG 1 is carried out. three FIG. 10 is a flow chart showing the manner of processing performed by the controller at time 70 ° B in FIG 1 is performed (time at which the signal SGT increases, that is, a time 70 ° before the time TDC (top dead center) with respect to the crank angle). Further shows 4 Fig. 10 is a flow chart showing the manner of the control quantity calculation processing performed by the controller every predetermined time.

First, in the in 2 shown step 101 the signal level of a signal SGC1 is read at the time TDC (time at which the signal SGT decreases).

Then in the in three shown step 102 the signal level of a signal SGC2 at time 70 ° B (time at which the signal SGT rises) is read.

Furthermore, in step 103 a cylinder of the internal combustion engine in which processing is currently to be performed is identified by combining the signal levels of the signal SGC1 and the signal SGC2.

In the following step 104 it is determined if at the step 103 identified cylinder the compression stroke injection is performed or not.

If it is determined that the compression stroke injection is not being performed, the operation goes to step 109 in which a suction stroke injection is performed. This control processing is similar to the conventional control processing in which it is determined whether or not an internal combustion engine is operated in a state in which the compression stroke injection is possible. Furthermore, in step 112 As will be explained in more detail below, it is determined whether the injection processing should be performed in either the compression or the intake stroke, and then an injector is operated by outputting a predetermined injection pulse based on the result of this determination.

If, by contrast, in step 104 is determined that the compression stroke injection is to be performed, the operation goes to step 105 in which it is determined whether knocking occurs or not.

When in step 105 it is determined that knocking occurs even if a compression stroke injection mode is employed, the operation goes to step 106 in which the knocking strength is detected and the amount of fuel to be injected into a cylinder that is in the intake stroke is calculated.

In the following step 107 the fuel is injected into the cylinder in the intake stroke, based on the amount of fuel to be injected in the intake stroke, in step 106 was calculated.

Then the operation goes to the step 108 in which a compression stroke injection is performed on that cylinder in which in step 107 a suction stroke injection was performed. The amount of fuel that is to be injected in the compression stroke, is obtained by the in the intake stroke in step 107 injected amount of fuel is subtracted from the amount of fuel injected in the compression stroke when knocking does not occur.

It should be noted that when in step 105 it is determined that knocking does not occur, the operation goes to step 108 passes, and a compression stroke injection is performed.

In the target control amount calculation routine, which in 4 are shown, control variables that in the compression stroke injection process in step 108 and in a suction stroke injection process in step 109 be regulated, calculated.

How out 4 1, a load condition of the engine is first detected according to the output from the throttle angle sensor 4 , in step 111 , and is the speed of the internal combustion engine 1 in accordance with the output signal SGT from the crank angle sensor 5 detected. Then, the operating state of the internal combustion engine 1 in the following step 112 determined on the basis of the speed of the internal combustion engine 1 , and the control mode of the internal combustion engine is set on the basis of the result of this determination.

Specifically, an injection mode (whether to inject fuel in the compression stroke injection mode or the suction stroke injection mode), an A / F control mode (either an O ₂ feedback mode or an open loop control mode), and a running mode (an idle mode, a steady running mode, or a transition running mode).

Then in step 113 determined whether the compression stroke injection is performed or not, based on the operating mode in step 112 was determined.

When in step 113 is determined that the Verdichtungshubbetriebsart is to be performed, the operation goes to step 114 in which various control setpoints for the compression stroke mode are calculated.

In contrast, if goes in step 113 it is determined that the compression stroke injection should not be performed, the operation flow to the step 115 in which various control setpoint values for the intake stroke injection are calculated.

As As described above, according to the present invention when knocking is caused due to a special operating condition, which occurs when the internal combustion engine with direct injection is operated in the compression stroke injection mode, in which it is theoretically unlikely that knocking will occur, knocking thereby suppressed be that in the impact the cylinder temperature is reduced by performing a Intake stroke injection in addition for compression stroke injection. Therefore, the compression ratio and set the ignition timing be without the above-described, special condition consider to have to (ie a high compression ratio the internal combustion engine itself, an ignition point presented, a high temperature of the intake air, using a very volatile Fuel, and not perfect distribution of the fuel in stratified Status). Therefore, an internal combustion engine can be provided which has a high output and an excellent output Driving behavior leads.

in the individual, when knocking occurs, part of the fuel, which is to be injected in the compression stroke, instead injected in the intake stroke, before the compression stroke, thereby a spontaneous inflammation of the fuel by reducing the temperature in the cylinder due the heat of vaporization repressed can be.

Even though the internal combustion engine is designed so that in itself no knocking during the Compression strokes in any condition except the above described special condition can occur, even if the internal combustion engine is operated in this special state, as a result of a change the operating conditions, the occurrence of knocking are suppressed thereby that one increase the cylinder temperature by injecting fuel in the intake stroke is limited.

The Amount of fuel to be injected in the intake stroke, must be accordingly an air / fuel ratio chosen be in which the fuel in the injected in the intake stroke Amount is not burned, and must be adjusted so that the output torque, the is produced by combustion of that amount of fuel which the Sum of the above Fuel quantity and that amount of fuel is in the same Cylinder is injected in the compression stroke, immediately after the intake stroke took place, approximately is equal to that output torque that is in another cylinder using the compression stroke injection immediately before Occurrence of knocking is generated.

If the amount of fuel to be injected in the intake stroke, As set out above, can be advantageous performance achieve without compromising drivability.

The Control device for the internal combustion engine with direct injection according to the present Invention is characterized in that it has injectors, which are arranged so that they directly fuel into the respective cylinder of the internal combustion engine inject; an intake air amount detector for detecting the Intake air amount supplied to the internal combustion engine; a crank angle detector for detecting a crank angle of Internal combustion engine; a throttle angle detector for detecting the angle of a throttle; a cylinder identification device for identifying a cylinder in which a combustion takes place; a knock detector for detecting knocking in the internal combustion engine; and a controller for controlling the fuel injection the internal combustion engine by calculating the amount of fuel that is injected into the internal combustion engine, based on the Signal, which is detected by the Ansaugluftmengendetektor, the Crank angle detector or the throttle angle detector, and through transmission the amount of fuel as an electrical signal to the injectors, wherein when knocking occurs in an operating state in which Fuel is injected in the compression stroke, fuel into one Cylinder is injected in the intake stroke at the time when knocking occurs. By this arrangement, even when knocking occurs, When the internal combustion engine in the compression stroke injection mode operated, in which knocking is unlikely, However, a special operating condition is present, the knocking thereby suppressed be that the Temperature in the cylinder by injection of fuel in this is lowered in the intake stroke before the compression stroke. In the control device according to the present Invention can therefore achieve high performance of the internal combustion engine be without any harm in terms of output power, fuel consumption and the like, in normal operating condition, even if a special operating condition is taken into account.

Since the amount of fuel to be injected into the cylinder, which is in the intake stroke, after knocking, accordingly the knocking condition is controlled, the knocking can be effectively suppressed.

There the amount of fuel to be injected into the cylinder which is in the intake stroke, after the occurrence of knocking, is set so the existence Air / fuel ratio made available in which the fuel is not ignited in the cylinder, can effectively suppress knocking become.

Furthermore is the amount of fuel that is injected into the cylinder which is in the intake stroke after knocking has occurred, preferably adjusted so that the Output torque caused by the combustion of an amount of fuel is generated, which is the sum of the above-mentioned amount of fuel and an amount of fuel entering the cylinder in a compression stroke is injected after the intake stroke, substantially equal to the Output torque is that generated by an amount of fuel which injected into the compression stroke without occurrence of knocking becomes. Therefore, the drivability with the internal combustion engine can be improved become.

Claims (3)

Control device ( 8th ) for an internal combustion engine ( 1 ) with direct injection, in which are provided: injectors ( 11 ), which are arranged so that they directly fuel into the respective cylinder of the internal combustion engine ( 1 ) inject; an intake air quantity detector ( 2 ) for detecting the intake air amount of the internal combustion engine ( 1 ) is supplied; a crank angle detector ( 5 ) for detecting the crank angle of the internal combustion engine ( 1 ); a throttle angle detector ( 4 ) for detecting the angle of a throttle valve; a cylinder identification device ( 14 ) for identifying a cylinder in which combustion occurs; a knock detector for detecting knocking in the internal combustion engine ( 1 ); and a control device ( 8th ) for controlling the fuel injection in the internal combustion engine ( 1 ) by calculating an amount of fuel that is in the internal combustion engine ( 1 ) is to be injected, based on the signal received from the intake air quantity detector ( 2 ) is detected, the crank angle detector ( 5 ), or the throttle angle detector ( 4 ), and for transmitting the amount of fuel as an electrical signal to the injectors ( 11 ), wherein when knocking occurs in an operating state in which fuel is injected in the compression stroke, fuel is injected into a cylinder in the intake stroke at the time when the knocking occurs, and the amount of fuel to be injected into the cylinder , which is controlled in the intake stroke after the occurrence of knocking according to a knocking condition. Control device ( 8th ) for an internal combustion engine ( 1 direct injection according to claim 1, characterized in that the amount of fuel to be injected into the cylinder, which is in the intake stroke, after the occurrence of knocking is set so that an air / fuel ratio is provided in which the fuel in the cylinder is not ignited. Control device ( 8th ) for an internal combustion engine ( 1 direct injection according to claim 1, characterized in that the amount of fuel to be injected into the cylinder, which is in the intake stroke, after the occurrence of the knocking is set so that the output torque, which is caused by the combustion of an amount of fuel, which is the sum of the said amount of fuel and that amount of fuel injected into the cylinder in a compression stroke after the intake stroke is substantially equal to the output torque generated based on the amount of fuel injected in the compression stroke when no knocking occurs.