EP2601397A2

EP2601397A2 - Adaptive method for fuel injector control and cylinder balancing

Info

Publication number: EP2601397A2
Application number: EP11728623.7A
Authority: EP
Inventors: Werner Hess; Klaus Ries-Mueller
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-08-02
Filing date: 2011-06-27
Publication date: 2013-06-12
Also published as: DE102010038779A1; WO2012016763A2; CN103189629B; WO2012016763A3; US20130180511A1; JP2013532798A; CN103189629A; JP5832536B2

Abstract

The invention relates to a method (61) for operating an internal combustion engine (11) having a plurality of combustion chambers (15), at least one combustion chamber (15) being assigned an injection valve (13) for injecting fuel (m_f) into the combustion chamber (15), wherein, for a least one combustion chamber (15), an air ratio (λ) that is individual to the combustion chamber is adjusted and/or, for at least one combustion chamber (15), a torque (M) that is individual to the combustion chamber is determined. In order to specify a method (61) for operating an internal combustion engine (11) with which, for individual combustion chambers (15), specific properties can be registered and, if necessary, accommodated, the intention being for faulty adaptations to be avoided to the greatest possible extent, it is proposed that, for at least one injection valve (13), an activation period (T_A) of the injection valve (15) is adapted (A) by measuring or determining a valve opening period (T) of the injection valve (15) in such a way that tolerances of the injection valve (15) with respect to a relationship between the activation period (T_A) and the valve opening period (T) are at least substantially compensated.

Description

Description title

Method for operating an internal combustion engine having a plurality of combustion chambers and internal combustion engine having a plurality of combustion chambers

State of the art

The invention relates to a method for operating an internal combustion engine having a plurality of combustion chambers, wherein at least one combustion chamber is assigned an injection valve for injecting fuel into the combustion chamber, wherein a combustion chamber-specific air ratio is adjusted for at least one combustion chamber and / or determines a combustion chamber-specific torque for at least one combustion chamber becomes.

From EP 1 169 560 B1 a method and a device for the

Determination of cylinder-individual differences of a control variable in a multi-cylinder internal combustion engine, for example, a gasoline engine with gasoline direct injection known. This method comprises a

Individual cylinder lambda control with which cylinder-specific air conditions can be regulated to a specific value. Furthermore, the method comprises the determination of cylinder-individual torque contributions of the individual cylinders. The known method is adaptive in the sense that it adapts to, for example, production-related tolerances between the individual cylinders. However, for detecting sensor signals used for this adaptation, it is commonly used

Internal combustion engines only a common sensor for all cylinders,

For example, a common lambda probe or a common

Rotary encoder present, so that the adaptation is relatively inaccurate and it can lead to Fehladaptionen. Disclosure of the invention

The present invention solves the problem of specifying a method for operating an internal combustion engine, with which specific properties can be detected and optionally compensated for individual combustion chambers, wherein

Misadaptations should be avoided as much as possible. Furthermore, the task includes specifying a corresponding internal combustion engine.

To solve this problem, a method for operating a

Internal combustion engine of the type mentioned above, which is characterized in that for at least one injection valve, a control period of the injection valve in such a way by detecting or determining a

Valve opening period of the injection valve is adapted to tolerances of the injection valve with respect to a relationship between the driving time and the valve opening duration are at least substantially offset.

Since a quantity of fuel injected into the combustion chamber generally depends on the activation duration, this adaptation ensures, at least in most cases, that tolerances of the injection valve are at least partially compensated for a relationship between the control of the injection valve and the fuel quantity. This ensures that

Differences between the individual combustion chambers, which relates to the filling (within a gas cycle in the combustion chamber introduced mass of fresh gas) and what concerns the fuel injected by the injector in the individual combustion chambers amount of fuel, can be adapted separately. In this case, it is preferable that the adaptation of the activation duration is carried out with higher priority than other adaptation processes, such as

For example, the cylinder-specific lambda control or possibly a control of the combustion chamber-specific torque. This allows

Deviations between the individual injection valves with one another, which can result, for example, from manufacturing tolerances or aging processes, can be detected and corrected particularly effectively.

It is preferred that, when adapting the activation duration, at least one valve delay time of the injection valve is determined by a time profile of at least one electrical variable at an electrically actuated actuator of the

Injector, preferably a current through the actuator detected and is evaluated. For example, the current can be detected by a coil of an electromagnetic actuator of the injection valve. The valve delay time corresponds to a response time of the valve to a

Control signal for opening or closing the injection valve. The determined valve delay time can be used to form a drive signal to set the injector at the right time for the right one

Open valve opening time.

Preferably, an opening delay time between a start of a control for opening the injection valve and an actual opening of the injection valve and / or a closing delay time between a start of a control for closing the injection valve and an actual closing of the injection valve is determined as the valve delay time. The start of the control for opening the injection valve may, for example, correspond to a start of energization of the coil of the injection valve. Accordingly, the beginning of a control for closing the injection valve can correspond to an end of the current supply of the coil.

The valve delay time is thus detected directly on the actuator of the injector. The actuator of the injection valve thus serves equally as a sensor, the

Detecting the valve delay time is used. By evaluating the

electrical quantity, for example of the current, for example, the end of a movement of a valve element of the injection valve can be detected directly. It is therefore not necessary to resort to sensor variables which are only indirectly related to the movement of the valve element, that is to say the opening and closing of the injection valve, and / or detected jointly for several or all combustion chambers of the internal combustion engine. Thus, that has

Method has the advantage that tolerances of the valve delay time can be detected directly at their source source and corrected if necessary. This leads to a high accuracy and reliability of the process. It can be provided that the valve duration of the injection valve (time period during which the injection valve is open) is calculated on the basis of the control period of the internal combustion engine (time period between activation for opening the injection valve and activation for closing the injection valve) and the valve delay times. It can be provided that it is checked whether an adaptation process for adapting the drive duration has settled, and

combustion chamber-individual torque is only determined if this

Verification has shown that the adaptation process has settled. In this way it can be achieved that, on the one hand, the adaptation of the

Fuel quantity is carried out with a comparatively high priority and on the other hand, that initially deviations of the individual injectors with each other, as far as the amount of fuel or the valve delay time, be corrected before trying to detect deviations of the filling of the individual combustion chambers with each other and / or compensate ,

It may also be provided that a control process for regulating the combustion chamber-specific air ratio is only started when the check as to whether the adaptation process has settled has shown that the

Adaptation process is settled. As a result, the adaptation process is assigned a higher priority than the control process for regulating the combustion chamber-specific air ratio.

It can also be provided that it is checked whether the control process for regulating the combustion chamber-specific air ratio has settled, and the combustion chamber-individual torque is only determined when this

Verification has shown that the control process has settled. As a result, errors in determining the combustion chamber-specific torque can be avoided, which can be caused by the fact that the air ratio is not yet adjusted to a predetermined value of, for example, A _so n = 1.

It is preferred that when determining the combustion chamber-specific torque at least one sensor size is detected, which characterizes a combustion chamber pressure in the respective combustion chamber, a rotational angle of a shaft, for example a crankshaft or a camshaft, the internal combustion engine and / or a rotational speed of the shaft of the internal combustion engine. In the case of

Angle of rotation or the speed can be the torque

For example, be determined that a change in the speed is detected or determined in a period in which the respective considered combustion chamber contributes to the generation of the total torque of the internal combustion engine. It is preferred that when determining the combustion chamber individual

Torque is a variable that characterizes a rough running of the internal combustion engine is calculated. The bigger the differences of the

combustion chamber-specific torques among each other, the greater is the

Running noise of the internal combustion engine.

As a further solution of the above object is a

Internal combustion engine proposed with a plurality of combustion chambers, wherein at least one combustion chamber, an injection valve for injecting a

Fuel quantity is assigned to the combustion chamber, the

Internal combustion engine, preferably a control device for controlling and / or regulating the internal combustion engine, for adjusting a combustion chamber-specific air ratio for at least one combustion chamber and for determining a

combustion-chamber-specific torque, which preferably corresponds to a contribution to a total torque on a shaft of the internal combustion engine, is arranged for at least one combustion chamber, proposed, which is characterized in that the internal combustion engine or the control device is so arranged and / or designed that for at least one Injection valve by detecting or determining a valve opening period of the injection valve a

Control period of the injection valve is adapted such that tolerances of the injection valve with respect to a relationship between the driving time and the valve opening period are at least substantially offset. With such an internal combustion engine, the advantages of

inventive method can be realized.

It is particularly preferred that the internal combustion engine or the

Control device for carrying out an above-described inventive method according to one of claims 1 to 8 set up, preferably programmed, is. For this purpose, the control device may have a computer, for example a microcontroller, which contains a memory element in which a program for carrying out a method according to the invention is stored.

Other features and advantages of the invention will become apparent from the

following description in which exemplary embodiments of the invention are explained in more detail with reference to the drawings. Showing: Figure 1 shows an internal combustion engine in a schematic representation and

FIG. 2 shows a flowchart of a method for operating the

Internal combustion engine of Figure 1.

In a shown in Figure 1 internal combustion engine 1 1 is

preferably an Otto engine with gasoline direct injection.

Accordingly, the internal combustion engine 1 1 has a plurality of injection valves 13, wherein each injection valve 13 is assigned a combustion chamber 15 (cylinder), so that the injection valve 13 can inject fuel directly into the respective combustion chamber 15. The internal combustion engine 1 1 also has a

for example, as a suction pipe 17 formed air supply line. About the suction pipe 17 can be supplied to the combustion chambers 15 via open inlet valves (not shown) from the environment of the internal combustion engine 1 1 fresh air 19. In a gas cycle cycle of a combustion chamber 15, this can be filled with a certain fresh gas filling of the mass m _g .

The internal combustion engine 1 1 has an exhaust system 21 with an exhaust pipe 23. With open exhaust valves (not shown) of the combustion chambers 15 can from the combustion chambers 15 gas, preferably exhaust gas, flow out and into the

Inlet pipe 23 flow. In the exhaust pipe 23 designed as a lambda probe 25 oxygen sensor of the exhaust system 21 is arranged. Each of the combustion chambers 15 has a reciprocable mounted in it

Piston, which in a known manner with a crankshaft 27 of the

Internal combustion engine 1 1 is coupled, which is converted in a combustion of fuel within the combustion chamber 15 resulting energy into a torque M acting on the crankshaft 27. The torque M is a combustion chamber-specific torque M, which is used to form a

Total torque M _{g contributes} to the crankshaft 27.

On the crankshaft 27 of the internal combustion engine 1 1, a speed sensor 29 is arranged, which is designed to detect a rotational speed n of the internal combustion engine 1 1. In one embodiment of the invention, it may be provided that by means of the speed sensor 29 and the instantaneous angle of rotation φ of the crankshaft 27 can be detected.

A coil 31 of an electromagnetic actuator (without

Reference numeral) of each injector 13 is connected to a control output of a control unit 35 for controlling and / or regulating the internal combustion engine 1 1, so that the control unit 35, the individual injection valves 13 for injecting a definable from the control unit 35 fuel quantity (mass m _f ) can control ,

To generate a corresponding actuating signal s, the control unit 35 has a power stage 37 of a drive circuit 39. The control circuit 39 of the control device 35 also includes a measuring circuit 41 for detecting the course of a current i through the coil 31 of the individual injection valves 13. By means of the control signal s, the control unit 35, the injectors 13 to open and close to control. The period between the triggering to open a particular injector 13 and the driving to close this injector 13 corresponds to a drive time T _A. In the illustrated embodiment, the drive duration T _A corresponds to a duration of energization of the coil 31 of this injector 13. In some

Embodiments of the invention may correspond to the drive duration T _{A of} a width of a drive pulses of the actuating signal s.

Furthermore, the lambda probe 25 is connected to an input of the control unit 35, so that the control unit 35 can detect an instantaneous air ratio λ of exhaust gas 43 flowing out of the combustion chambers 15.

The control unit 35 has a computer, for example a microcontroller 45. The computer or microcontroller 45 can

Memory element, in particular a semiconductor memory 47, which is programmed to carry out a method for operating the internal combustion engine 1 1.

Such a method 61 will be explained in more detail below with reference to the flowchart shown in FIG. After a start 63 of the method 61, an adaptation process A for adapting the fuel quantity m _f is performed in a step 65 started. The adaptation process compensates tolerances of the individual

Injectors 13 with respect to a relationship between the control of the injectors 13 by means of the control signal s and the resulting from the control amount of fuel m _f , as far as they come from deviations in a valve opening period T. In this adaptation process A detects the

Measuring circuit 41 a current i through the coil 31 of each injector 13. Based on the current i determines the controller 35 the time when the valve 13 has actually opened or closed. These times are recognized on a characteristic feature of the time course of the current i, which stems from the fact that a valve needle of the injection valve 13 strikes when the injection valve 13 is opened or closed, thereby giving repercussions on the current i through the coil 31.

By comparing the time points of the opening or closing of the injection valve 13 detected on the basis of the current i with the known time

Course of the control signal s determines the control unit 35 individually for each injector 13 an opening delay time t-ι, a Schließverzugszeit t ₂ and / or a valve opening period T. The opening delay time t-ι is the delay between a start of the control means of the Actuator s for opening the injector 13, that is, a beginning of a

Energizing the coil 31, and the actual opening of the injection valve, that is, a striking of the valve needle in a position of the valve needle, in which the injection valve 13 is opened. The closing delay time t ₂ is a delay between a start of the activation for

Closing of the injection valve 13 by means of the actuating signal s, that is one

End of the energization of the coil 31, and an actual closing of the injection valve 13, that is, a striking of the valve needle 31 in a position of the valve needle with the injector 13 closed, for example, a striking on a valve seat.

Based on the valve delay times ti, t ₂ , the control unit 35 corrects the time and duration of the energization of the coil 31 by means of the control signal s so that one of other, not described here functions of the control unit 35 predetermined amount of fuel m _{f is} injected into the individual combustion chambers 15 , Characterized in that for each injection valve 13, the valve delay times t-ι, t _{2 are} determined and taken into account when generating the actuating signal s, Are manufacturing tolerances or age-related tolerances, what the connection between a driving time, that is, a time of

Energizing the coil 31, and a period in which the injection valve 13 is opened (valve opening period T), at least substantially balanced.

For the adaptation process A, several measurements of the course of the current i may be required. It can be provided that the

Valve delay times t-ι, t ₂ for different operating conditions of

Internal combustion engine 1 1, for example, for different values of a

Fuel pressure in a high-pressure fuel storage (not shown) can be determined. Consequently, it is checked in a step 67 whether sufficient measurements of the profile of the current i or sufficient values of the valve delay times t- ₁ , t _{2 have been} determined, that is, it is checked whether the adaptation process A is in a steady state. If this is not the case (N), the branch 67 is repeated. Otherwise (Y), the method 61 is continued with a step 69.

In this step 69, a control process R for regulating the

combustion chamber-specific air ratio started. According to this control process R, the control unit 35 detects by means of the lambda probe 25 separately for each combustion chamber 15, the air ratio λ and changes, if necessary, control variables of

Internal combustion engine 1 1, in order to approximate the detected value λ of the air ratio to a predetermined desired value. For example, the amount of fuel m _f depending on the detected air ratio λ can be changed. Deviating from the embodiment shown, the step 69 can also be an earlier

Time to be executed in the course of the process 61. For example, the control process can be started immediately after the start 63 of the method or after the step 65. Subsequently, it is checked in a step 71 whether the one described above

Control process of the combustion chamber-individual lambda control

has settled, that is, whether the values of the air ratio λ detected for the individual combustion chambers 15 are sufficiently close to the desired value, for example A _S0 || = 1, have approximated and / or whether the detected value λ varies with a sufficiently small amplitude around the setpoint. If it is detected that the cylinder-specific lambda control R has not yet settled (N), then step 71 is repeated. Otherwise (Y), a step 73 is continued.

In step 73, the combustion chamber-individual torque M is determined. For this purpose, the instantaneous speed n of the crankshaft 27 is detected. It may be provided that the rotational speed n is evaluated for a rotational angle range of the crankshaft 27 (or a corresponding time interval) in which a specific combustion chamber contributes to the generation of the total torque M _g . In this way, the respective torque M can be determined in succession for each combustion chamber 15. As a measure of the torque M, for example, a time change n 'of the speed, that is, a derivative of the speed after time, are used. It can also be done by means of a

Combustion chamber pressure sensor a combustion chamber pressure p within the individual

Combustion chambers 15 are detected and the torque M are determined at least on the basis of the combustion chamber pressure p and / or on the basis of its time course. Deviating from or in addition thereto, the internal combustion engine 1 1 may have a torque sensor for detecting the torque M and / or the total torque M _g , and in step 73 the torque M or the total torque M _{g may} be detected by means of the torque sensor. In addition, a characteristic L, which is a rough running of the

Internal combustion engine 1 1 characterized, are determined.

Since by means of the adaptation A of the control of the injectors 13 deviations of the injected fuel quantity m _f as a function of tolerances of the injection valve 13, in particular the valve delay times t-ι, t ₂ , at least largely balanced, can with relatively great certainty

be assumed that differences in the combustion chamber individual

Torques M among each other especially of differences between the fresh gas fills m _{g of} the individual combustion chambers 15 result. In a step 75 following the step 73, the torque M can be determined for each

Combustion chamber 15, the corresponding fresh gas filling m _{g are} calculated.

Alternatively or additionally, differences between the individual fillings m _g can also be calculated. In general, there is one

Proportionality between the torque M and the fresh air filling m _g , so that at a known proportionality constant, the fresh air filling m _g or the differences between the fresh air fills m _g the individual combustion chambers 15 can be calculated. Although the combustion chamber individual torques M and the characteristic variable L for the uneven running are of several sizes such as a deviation of the fuel quantities m _f between the individual combustion chambers 15, deviations of

Fresh air fills m _{g of} the individual combustion chambers 15 with each other and from

Deviations of a firing angle between the individual combustion chambers 15 influenced. However, since by means of the adaptation process A, the deviations between the individual combustion chambers 15, which concerns the fuel quantity m _f , have been at least largely eliminated, it can be concluded that deviations of the individual torques M from each other and the

Unrest L mainly caused by deviations of the fresh air fillings m _g among themselves. The deviations in the ignition angle in this case have a relatively small influence on the differences between the torques or on the Laufunruhe L.

In a further embodiment of the method 61, a step 77 is provided, in which the differences between the torques M or the rolling noise L are reduced. It can be provided that, for example, for a combustion chamber 15 which generates a relatively low torque M compared to the other combustion chambers 15 and thus causes a running noise of the internal combustion engine 1 1, the fuel quantity m _{f is} increased. However, since in particular at the start of the internal combustion engine 1 1 and at a low load of the internal combustion engine 1 1 increasing the fuel amount m _f can lead to an increase in pollutant emissions, such as emissions of soot, it is preferred that a change in

Fuel quantity m _{f is performed} only when the internal combustion engine 1 1 is not in the starting process and / or when the load of

Internal combustion engine is greater than a predetermined minimum value or equivalent to this minimum value. As a measure of the load of the internal combustion engine, for example, the total torque M _{g can be} provided. The minimum value would then correspond to a minimum total torque.

In some cases, individual injection valves 13 may also deviate in relation to an association between an actual valve opening duration and the injected fuel quantity m _f . With the same valve opening period T thus differs in different Combustion chambers injected fuel quantity m _f . This deviation may be due to wear of the injector 15 or deposits, in particular

Deposits of soot or coking, be caused at the injection valve 15. This deviation can not be compensated by the adaptation process A, since the adaptation process A can only detect deviations with respect to a relationship between the activation duration (that is to say an energization duration of the coil 31) and the actual opening time of the injection valve 13. However, these deviations could be compensated in step 77.

It is conceivable that in step 77 to compensate for the different

Torques M or for reducing the uneven running L additionally or alternatively for changing the fuel quantity m _{f is set} an ignition angle for that combustion chamber 15 or those combustion chambers 15 whose torque M of a desired torque or torque M, which generate the other combustion chambers 15 differs. This way a can

Equalization of the torques M of the individual combustion chambers 15 are at least approximately achieved.

The method 61 shown in FIG. 2 may during operation of the

Internal combustion engine 1 1 regularly, for example, periodically, upon the occurrence of certain operating conditions 1 1 or when switching between

Operating conditions of the internal combustion engine 1 1 are executed.

In one embodiment, not shown, the combustion chamber-individual air ratio is not adjusted for the individual combustion chambers 15. Here, the step 69 and the branch 71 can be omitted.

In a further embodiment not shown, the

combustion chamber individual torque is not determined. Here, the steps 75 and 77 can be omitted.

Overall, the present invention provides the method 61 for operating the internal combustion engine 1 1, which makes it possible to coordinate different adaptation and control methods for controlling and / or regulating the fuel quantity m _f and the fresh gas filling m _g so that tolerances the individual injectors 13 are balanced and At the same time, positive feedback and misadaptations are at least largely avoided.

Claims

claims

1 . Method (61) for operating an internal combustion engine (1 1) with a plurality of combustion chambers (15), wherein at least one combustion chamber (15) a

Injection valve (13) for injecting fuel (m _f ) is assigned to the combustion chamber (15), wherein for at least one combustion chamber (15) a

adjusted for individual combustion chamber (λ) and / or for each at least one combustion chamber (15) a combustion chamber-specific torque (M) is determined, characterized in that for at least one injection valve (13) a drive time (T _A ) of the injection valve (15) by such Detecting or determining a valve opening duration (T) of the injection valve (15) adapted (A), that the tolerances of the injection valve (15) with respect to a

Relationship between the driving time (T _A ) and the

Valve opening period (T) are at least substantially offset.

2. The method (61) according to claim 1, characterized in that

Adapting (A) the activation duration (T _A ) at least one valve delay time (ti, t ₂ ) of the injection valve (15) is determined by a time course of at least one electrical variable at an electrically actuated actuator (31) of the injection valve (15), preferably a current (i) is detected and evaluated by the actuator (15).

3. The method (61) according to claim 2, characterized in that as

Ventilverzugszeit an opening delay time (t-ι) between a start of a control for opening the injection valve (15) and an actual opening of the injection valve (15) and / or a closing delay time (t ₂ ) between a start of a control to close the

Injection valve (15) and an actual closing of the injection valve (15) is determined. 4. The method (61) according to any one of the preceding claims, characterized

characterized in that it is checked (67) whether an adaptation process (A) for Adapting the drive duration (T _A ) is settled, and the

combustion chamber-individual torque (M) is only determined when this check (67) has shown that the adaptation process (A)

has settled.

Method (61) according to one of the preceding claims, characterized in that a control process (R) for regulating the

combustion chamber-specific air ratio only started (69), if the check (67), whether the adaptation process (A) has settled, has shown that the adaptation process (A) has settled.

Method (61) according to one of the preceding claims, characterized in that it is checked (71) whether the control process (R) for regulating the combustion chamber-specific air ratio (λ) has settled, and the combustion chamber-individual torque (M) is only determined if this check (71) has shown that the control process (R) has settled.

Method (61) according to any one of the preceding claims, characterized in that when determining (73) the combustion chamber-specific torque (M) at least one sensor size is detected, a combustion chamber pressure (p) in the respective combustion chamber (15), a rotation angle (φ) a Shaft (27) of the internal combustion engine (1 1) and / or a rotational speed (n) of the shaft (27) of the internal combustion engine (1 1) characterized.

A method according to claim 7, characterized in that when determining (73) of the combustion chamber-specific torque (M) a variable (L), which characterizes a rough running of the internal combustion engine (1 1) is calculated.

Internal combustion engine (1 1) with a plurality of combustion chambers (15), wherein at least one combustion chamber (15) is associated with an injection valve (13) for injecting fuel (m _f ) into the combustion chamber (15), wherein the internal combustion engine (1 1) for regulating a combustion chamber-specific air ratio (λ) for at least one combustion chamber (15) and / or for determining a combustion chamber-specific torque (M) for at least one combustion chamber (15) is arranged, characterized in that the internal combustion engine (1 1) so arranged and / or is designed such that for at least one injection valve (15) by detecting or determining a valve opening duration (T) of the injection valve (15), a control period of the injection valve (15) is adapted such that tolerances of the injection valve (15) with respect to a relationship between the drive duration (T _A ) and the valve opening duration (T) are at least substantially offset.

10. Internal combustion engine (1 1) according to claim 9, characterized in that the internal combustion engine (1 1) has a control device (35) for controlling and / or regulating the internal combustion engine (1 1), which for carrying out a method (61) after a of claims 1 to 7,

is preferably programmed.