EP1611318A1

EP1611318A1 - Method for controlling an internal combustion engine

Info

Publication number: EP1611318A1
Application number: EP04702296A
Authority: EP
Inventors: Franz Kunz; Hong Zhang
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2003-02-20
Filing date: 2004-01-15
Publication date: 2006-01-04
Anticipated expiration: 2024-01-15
Also published as: EP1611318B1; DE10307307B4; DE10307307A1; DE502004003137D1; US7093573B2; WO2004074646A1; US20050229884A1

Abstract

The invention relates an internal combustion engine comprising a camshaft, whereby the phase thereof can be adjusted in relation to the crankshaft by means of an adjusting device. The invention also comprises a camshaft sensor which detects the angle of the camshaft (CRK) and a crankshaft sensor which detects the angle of the crankshaft (CAM). Said method comprises the following steps: A reference value (PH AD) of the phase is adapted in a predetermined position of the adjusting device when a predetermined condition is fulfilled. A measuring value (PH S) of the phase is determined according to the detected angle of the crankshaft (CRK) and the angle of the camshaft (CAM). A corrected measuring value of the phase is determined according to the reference value (PH AD) and the measuring value (PH S) of the phase. An actuator signal for controlling the internal combustion engine is determined according to the corrected measuring value.

Description

description

Method for controlling an internal combustion engine

The invention relates to a method for controlling an internal combustion engine with a camshaft, the phase of which can be adjusted to a crankshaft by means of an adjusting device.

From DE 101 08 055 Cl a method for controlling an internal combustion engine with a camshaft is known, the phase of which can be adjusted to a crankshaft by means of an adjusting device. The adjusting device disclosed there is a hydraulic system by means of which the phase between the crankshaft and the camshaft can be adjusted. Such adjusting devices are widely used in modern internal combustion engines and serve on the one hand to increase performance and on the other hand to reduce emissions in the internal combustion engine.

In the method known from DE 101 08 055 C1, a measured value of the phase between the crankshaft and the camshaft is determined as soon as the internal combustion engine starts, depending on the detected cam and crankshaft angles. A predetermined initialization value is read from a memory. The initialization value of the phase position is the value of the phase that the camshaft and crankshaft have with one another when all mechanical parts are arranged with respect to one another in the predetermined manner. Initialization values of this type are typically predefined by the manufacturer of the internal combustion engine for all internal combustion engines in a series and are stored in the control devices provided for this purpose.

A correction value for the phase is then determined as soon as the internal combustion engine starts, depending on the difference between the initialization value and the measured value of the phase. in the If the internal combustion engine continues to operate, the current phase is then determined from the sum of the measured value and the correction value. In the known method it is assumed that errors in the measured value of the phase are essentially due to the tolerances of the crankshaft sensor and the camshaft sensor. However, it has been shown that despite these corrections, a desired low-emission operation of the internal combustion engine is not always guaranteed.

The object of the invention is to provide a method for controlling an internal combustion engine with a camshaft, the phase of which can be adjusted to a crankshaft by means of an adjusting device, which ensures low-emission operation.

The object is achieved by the features of the independent claim. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is based on the knowledge that an error occurs during the operation of the internal combustion engine when the initialization value is rigidly assigned to a reference value during operation of the internal combustion engine when the control signal is generated. It has surprisingly been shown that errors are not only due to tolerances and drift phenomena of the crankshaft sensor and the camshaft sensor, but also to changes or wear in the area of the adjusting device or other elements which serve to couple between the crankshaft and the camshaft, such as a corresponding gear or chain. For example, significant changes in the actual phase position between the crankshaft and the camshaft can occur which, for example, can make up in comparison with the initialization value for the phase position and up to H-15 ° crankshaft and thus have a significant influence on the mass flow supply into the cylinders of the internal combustion engine. Based on this finding, a reference value of the phase in a predetermined position of the adjusting device is adapted in accordance with the subject matter of the independent patent claim if a predetermined condition is met. As the internal combustion engine continues to operate, a corrected measured value of the phase is then determined as a function of the reference value and a measured value of the phase. It can then be easily ensured that the internal combustion engine can be operated with low emissions.

In an advantageous embodiment of the invention, the predefined condition is met if a motor vehicle in which the internal combustion engine can be arranged has traveled a predefined driving distance since the last adaptation and there are predefined environmental conditions. This configuration of the condition is characterized by the fact that it guarantees simple and precise adaptation with an appropriate computational effort.

A further advantageous embodiment of the invention is characterized in that the ambient conditions are present when the temperature of the internal combustion engine is within a predetermined range. This has the advantage that no adulteration caused by a temperature drift of the sensors that may actually occur is included in the adaptation.

If the adaptation takes place shortly after the start of the internal combustion engine, this has the advantage that the adjusting device is in the end position predetermined by the mechanics, and thus a precise adaptation of the reference value is ensured.

If the adaptation is dependent on a variable that characterizes the load on the internal combustion engine, then a precise adaptation can easily be carried out, since the load the internal combustion engine is largely responsible for changes in the reference position.

The method becomes particularly simple if the quantity that characterizes the load on the internal combustion engine is the driving distance, or the method becomes particularly precise if this quantity is a quantity that characterizes the full load acceleration.

It is particularly advantageous if the variable characterizing the load on the internal combustion engine is a variable characterizing the uneven running. As a result, the method becomes particularly precise and can fall back on a quantity that is calculated anyway for other control or diagnostic functions of the internal combustion engine in a control of the internal combustion engine.

The method is also particularly simple when the size, the load on the internal combustion engine, and the operating time of the internal combustion engine.

It is also particularly advantageous if the internal combustion engine is diagnosed as a function of the adapted reference value or a value determining the adaptation, so at the same time an exact diagnosis is made possible with a value which is calculated with the method anyway.

Embodiments of the invention are explained below with reference to the schematic drawings. Show it:

1 shows an internal combustion engine with a control device in which the method for controlling the internal combustion engine is executed, FIG. 2 shows an adjustment device assigned to the internal combustion engine according to FIG. 1 for adjusting the phase between a camshaft and a crankshaft, FIG. 3 valve stroke progression curves of the gas exchange valves, plotted over the crankshaft angle,

FIG. 4 shows a flowchart of a program of part of the method for controlling the internal combustion engine,

5, 6 show a flowchart of a program of a further part of the method for controlling the internal combustion engine,

7 shows a program of a method for diagnosing the internal combustion engine.

Elements of the same construction or function are provided with the same reference symbols in all figures.

An internal combustion engine (see FIG. 1) comprises an intake tract 1, an engine block 2, a cylinder head 3 and one

Exhaust tract 4. The intake tract preferably comprises a throttle valve 11, further a collector 12 and an intake manifold 13, which is led to a cylinder ZI via an inlet duct in the engine block. The engine block further comprises a crankshaft 21 which is coupled to the piston of the cylinder ZI via a connecting rod.

The cylinder head comprises a valve train with an inlet valve 30, an outlet valve 31 and valve drives 32, 33. The gas inlet valve 30 and the gas outlet valve 31 are preferably driven by means of a camshaft 36 (see FIG. 2) or, if appropriate, by means of two camshafts, one each Gas inlet valve 30 and the gas outlet valve 31 is assigned. The drive for the gas inlet valve 30 and / or the gas outlet valve 31 preferably includes, in addition to the camshaft 36, an adjusting device 37, which is coupled on the one hand to the camshaft 36 and on the other hand to the crankshaft 21, for. B. over sprockets, which are coupled together via a chain. The phase between the crankshaft 21 and the camshaft 36 can be adjusted by means of the adjusting device. In the present exemplary embodiment, this is done by increasing the pressure in the High-pressure chambers 38 of the adjusting device 37 or lowering the corresponding pressure depending on the direction in which the adjustment is to take place. The possible adjustment range is indicated by arrow 39 in FIG.

The valve lift curves 46, 47 (FIG. 3) of the intake valves 30 and exhaust valves 31, shown in dashed lines, show the case in which they match the initialization value. However, during the operation of the internal combustion engine, these valve lift curves can change towards the valve lift curves 45 and 48. The consequence of this is that in the end position of the adjusting drive the valve overlap between the gas inlet and gas outlet valves can be different from the original valve overlap and also their phases or their position can be shifted in relation to the crankshaft angle.

Tests have shown that this can result in a shift of up to +/- 15 ° crankshaft. Such displacements then lead to changed gas exchange processes and changed combustion processes, as a result of which it is then no longer possible to ensure without the method described below that the desired torque is set on the one hand and low-emission operation of the internal combustion engine is ensured on the other hand.

The cylinder head 3 (FIG. 1) further comprises an injection valve 34 and a spark plug 35. Alternatively, the injection valve can also be arranged in the intake duct.

A catalyst 40 is arranged in the exhaust tract. Furthermore, a control device 6 is provided, to which sensors are assigned, which detect different measured variables and each determine the measured value of the measured variable. Depending on at least one of the measured variables, the control device 6 determines manipulated variables, which are then converted into one or more actuating signals for controlling the actuators can be implemented by means of appropriate ^'actuators.

The sensors are a pedal position sensor 71, which detects the position of an accelerator pedal, an air mass meter 14, which detects an air mass flow upstream of the throttle valve 11, a temperature sensor 15, which detects the intake air temperature, a pressure sensor 16, which detects the intake manifold pressure, a crankshaft angle sensor 22, which a crankshaft angle CAM, another temperature sensor 23, which detects a coolant temperature, a camshaft sensor 36, which detects the camshaft angle CRK, and an oxygen probe 41, which detects the residual oxygen content of the exhaust gas in the exhaust tract 4 and assigns an air ratio to the latter. Depending on the embodiment of the invention, any subset of the sensors mentioned or additional sensors can be present.

The actuators are, for example, the throttle valve 11, the gas inlet and gas outlet valves 30, 31, the injection valve 34, the spark plug 35. They are controlled by means of electrical, electromechanical, hydraulic, mechanical piezo or other actuators known to the person skilled in the art. In the following, reference is made to the actuators and actuators with actuators.

In addition to the cylinder ZI shown in detail, further cylinders Z2 to Z4 are generally also present in the internal combustion engine, to which corresponding intake pipes, exhaust gas channels and actuators are then assigned.

FIG. 4 shows a flow chart of a program of a first part of the method for controlling the internal combustion engine. The program is started in a step S1, preferably when the internal combustion engine has been fully assembled and is subjected to a final test, the so-called end of tape test. However, it is also advantageous to use the method in each case to start when mechanical interventions in the crankshaft 21, the camshaft 36, the adjusting device 37 or in other parts serving for coupling between the crankshaft 21 and the camshaft 36 have taken place. Such a case exists, for example, when the chain, via which the crankshaft is coupled to the camshaft, is exchanged or has been retensioned.

In a step S2, a measured value of the phase is calculated depending on the measured values of the camshaft angle CAM and the crankshaft angle CRK determined by the camshaft sensor 36a and the crankshaft angle sensor 22. The phase between the camshaft and the crankshaft is based on the degree crankshaft, the top dead center TDC of the piston assigned to the cylinder ZI and the vertex of the

Valve lifting VL of the inlet valve 30 or the outlet valve 31. The measurement value PH_S of the phase is detected in step S2 under predetermined ambient conditions, preferably at a predetermined temperature of the internal combustion engine.

In a step S3 it is checked whether the measured value PH_S deviates more than a first threshold value HYS from the initialization value PH_INI of the phase. The initialization value PH_INI is a predetermined value of the phase for several identical internal combustion engines, for example a series of internal combustion engines. The initialization value PH_INI of the phase is ideally assumed by all internal combustion engines when the adjusting device is at its end stop, which is predetermined by the base point of arrow 39 in FIG. 2.

If the deviation in step S3 exceeds the threshold value HYS, emergency operation of the internal combustion engine is controlled in a step S4, in which only limited operation of the internal combustion engine is made possible. If the program is started in step S1 during a nes tape end test, it can also be signaled in step S8 by suitable means that the internal combustion engine is not properly installed or is not functional.

However, if the condition of step S3 is not met, the measured value PH_S is assigned to the initialization value PH_INI in a step S5. As a result, the phase present in the respective individual internal combustion engine is then precisely stored in the end stop of the adjusting device 37. The program is then ended in a step S6.

A program for a further part of the method for controlling the internal combustion engine is started in a step S7 (see FIG. 5).

In a step S8, a measured value PH_S of the phase is determined depending on the detected crankshaft angles CRK and camshaft angles CAM. In a step S9 it is checked whether an update condition UPD is fulfilled. It is preferably checked whether the internal combustion engine was started promptly, i.e. whether it is still within the first revolutions of the crankshaft. It is also checked whether a minimum number of kilometers traveled has been reached since the last adaptation of a reference value PH_AD. Finally, it is checked whether given environmental conditions, such as preferably a predetermined temperature of the internal combustion engine, are met. The temperature of the internal combustion engine is preferably determined as a function of the detected coolant temperature.

If the conditions of step S9 are met, an adaptation value AD is determined in step S10. The n enclosed in square brackets means that the assigned value is valid as a new value for the current calculation run, whereas n-1 means that the corresponding The value in the previous calculation run was the current value.

The adaptation value is determined in step S10 depending on the adaptation value from the past calculation run, and / or a driving distance DIST and / or a number of full-load accelerations LJ and / or an operating period LT. It can also be determined additionally or exclusively as a function of a variable that characterizes the uneven running of the internal combustion engine or another variable that characterizes the load on the internal combustion engine over its operating time. In a step S11, a reference value PH_AD for the phase of the crankshaft and the camshaft in the end position of the adjusting device 37 is then determined from the sum of the initialization value and the current adaptation value AD.

In a step S12, a correction value PH_COR is then determined depending on the reference value PH_AD and the measured value PH_S of the phase. This correction value PH_COR then additionally compensates for temperature and other sensor errors. Step S12 is also processed if the conditions of step S9 are not met.

Concrete embodiments of the determination of the adaptation value AD in step S10 are shown in steps S13 to S16. For example, the adaptation value is determined using the formula given in step S13, where Min represents a minimum selection between the two terms separated by commas. The second ter of the minimum selection is the difference between two values, which are determined depending on the driving distance at the current calculation time and at the previous calculation time and thus represent a maximum change in the adaptation value AD between two successive adaptations. These values are preferably determined by corresponding driving tests and / or a corresponding model formation, and preferably in one Map stored. This procedure ensures in a simple manner that the change in the adaptation value AD in step S13 is limited in terms of amount to a maximum change specified by modeling.

The procedure according to step S14 in determining the adaptation value AD differs from that in step S13 in that the second term of the minimum selection is a value which is determined as a function of the difference between the current driving distance DIST and that in the last run of step S14 existing driving distance DIST is determined. The value also represents a model value, in which, in contrast to step S13, it is not the absolute driving distances that are decisive, but only the relative driving distances are taken into account. Here, too, the value is preferably calculated using a map.

In steps S15 and S16, the adaptation value is calculated by means of PTI filtering. For this purpose, a term is added to the adaptation value determined in the last run of step S15, which term contains a weighting value that is dependent on the difference in the driving distance DIST at the current calculation time and that during the last calculation run in step S15. This weighting value is multiplied by the difference between the deviation of the current measured value PH_S and initialization value PH_INI and the adaptation value in the previous calculation run of step S15. The weighting factor is preferably determined from a map stored in the control device 6, which was determined by driving tests or on the engine test bench.

The step S16 differs from the step S15 in that the weighting factor is additionally or alternatively determined as a function of a variable which characterizes the full-load accelerations, that is to say, for example, the number thereof. The procedure described in steps S13 to S16 The advantages of determining the adaptation value are that the relevant variables there have an influence on the change in the reference position and thus contribute to an exact and precise adaptation.

In a step S17 (see FIG. 6), which follows the step S12, the program goes into a waiting state until a predetermined period of time has expired or the crankshaft has moved on by a predetermined angle. In this state, the program is preferably interrupted and the computing power of the control device 6 is made available to other programs.

In a step S18, a measured value PH_S of the phase is then determined as a function of the camshaft angle CAM and the crankshaft angle CRK. In a step S19, a corrected measured value PH_AKT is then determined from the sum of the measured value PH_S and the correction value PH_COR.

In a step S20, an actuating signal SG for controlling the internal combustion engine is then determined as a function of the corrected measured value PH_AKT. This is done, for example, by means of a so-called intake manifold model, which uses appropriate observer equations to determine an estimated value of the air mass metered into the cylinder ZI depending on the corrected measured value PH_AKT of the phase between the crankshaft 21 and the camshaft 36 and other measured variables, such as the detected air mass flow Degree of throttle valve opening, the temperature of the intake air and, if applicable, the recorded intake manifold pressure. Depending on the estimated value of the air mass metered in the cylinder ZI, a desired fuel mass is then determined and the injection valve 34 is then controlled by means of a corresponding control signal. In a step S21 it is then checked whether an abort condition of the program is fulfilled. This can consist, for example, in that the internal combustion engine is stopped. If the condition of step S19 is met, the program in the Step S22 ends. Otherwise, the program continues in step S17.

The internal combustion engine is diagnosed using the program shown in FIG. The program is started in a step S23. In a step S24, it is checked whether the current adaptation value is greater than a further threshold value SWA. The further threshold value SWA is fixed and is preferably determined by tests on an engine test bench or while driving. If the condition of step S24 is fulfilled, then the internal combustion engine is put into an operating state of emergency operation in a step S25. If, on the other hand, the condition of step S24 is not met, the program is ended in step S26. As an alternative to step S24, a step S27 can also be provided in which it is checked whether the change in the adaptation values from a calculation time of the adaptation value to the next calculation time exceeds a predetermined further threshold value SWB. If this is the case, the internal combustion engine is controlled in the operating state of the emergency operation in step S25. Otherwise, the program is ended in step S26.

Claims

claims

1. A method for controlling an internal combustion engine having a camshaft (36) whose phase can be adjusted to a crankshaft (21) co ^■ means of an adjusting device (37), having a crankshaft sensor (22) which senses the crankshaft angle (CRK) and a camshaft sensor (36a) which detects the camshaft angle (CAM) with the following steps

a reference value (PH_AD) of the phase is adapted in a predetermined position of the adjusting device (37) if a predetermined condition is met,

- A measured value (PH_S) of the phase is determined depending on the detected crankshaft angle (CRK) and camshaft angle (CAM), - A corrected measured value (PH_AKT) of the phase is determined depending on the reference value (PH_INI) and the measured value (PH_S) of the phase .

- An actuating signal (SG) for controlling the internal combustion engine is determined depending on the corrected measured value (PH_COR).

2. The method according to claim 2, characterized in that the predetermined condition is met if a motor vehicle in which the internal combustion engine can be arranged has traveled a predetermined driving distance (DIST) since the last adaptation and predetermined environmental conditions exist.

3. The method according to claim 2, characterized in that the ambient conditions are present when the temperature of the internal combustion engine is within a predetermined range.

4. The method according to any one of the preceding claims, characterized in that the adaptation takes place promptly to the start of the internal combustion engine.

5. The method according to any one of the preceding claims, characterized in that the adaptation is dependent on a size that characterizes the load on the internal combustion engine.

6. The method according to claim 5, characterized in that the quantity that characterizes the load on the internal combustion engine is the driving distance (DIST).

7. The method according to any one of claims 5 or 6, characterized in that the variable which characterizes the load on the internal combustion engine is a variable which characterizes the full-load accelerations.

8. The method according to any one of claims 5 to 7. characterized in that the size that characterizes loads on the internal combustion engine is a size that characterizes the uneven running.

9. The method according to any one of claims 5 to 8, characterized in that the quantity that characterizes the load on the internal combustion engine is the operating time period (LT) of the internal combustion engine.

10. The method according to any one of the preceding claims, characterized in that the internal combustion engine is diagnosed as a function of the adapted reference value (PH_AD) or a value determining the adaptation.