DE10142493A1 - Method for operating a direct injection internal combustion engine - Google Patents

Abstract

The invention relates to a method for operating a direct-injection internal combustion engine (1), especially for a motor vehicle, according to which the fuel is at least temporarily injected into a combustion chamber (4) of the internal combustion engine (1) in such a manner and air is at least temporarily supplied to the combustion chamber (4) in such a manner that the mixture from fuel and air is present in the combustion chamber (4) as a stratified charge. The fuel/air mixture is ignited at a defined point (tzünd) and a temperature (Tmot) specific for the internal combustion engine (1) is determined. In order o optimize operation of the internal combustion engine (1) especially after a cold start, the ignition point (t'zünd) determined in a conventional manner is modified subject to the determined temperature (Tmot). The corrected ignition point (tzünd) is used to control a spark plug (10) of the internal combustion engine (1).

Description

State of the art

The present invention relates to a method for Operating a direct-injection internal combustion engine especially for a motor vehicle. In the process Fuel in at least one combustion chamber Internal combustion engine injected at least temporarily and air to the combustion chamber at least temporarily supplied that the mixture of fuel and air in the Combustion chamber is layered. The fuel-air mixture will ignited at a predetermined time. In the process becomes a temperature specific to the internal combustion engine determined.

The invention also relates to a memory element, in particular a read-only memory, a random access memory or a flash memory, for a control and / or regulating device an internal combustion engine, in particular for a Motor vehicle. On the storage element is a Computer program stored on a computing device, is executable, in particular on a microprocessor.

The present invention further relates to a Computer program running on a computing device, in particular on a microprocessor, is executable.

The invention also relates to a control and / or Control device for operating an internal combustion engine, especially for a motor vehicle. The tax and / or Control device initiates an injection, at least temporarily of fuel in a combustion chamber of the internal combustion engine and an at least temporary supply of air into the Combustion chamber so that the mixture of fuel and air is layered in the combustion chamber. The tax and / or Control device causes the fuel-air to ignite Mixtures at a predeterminable time and taken into account when operating the internal combustion engine one for the Internal combustion engine specific temperature.

Finally, the present invention relates to a Internal combustion engine, in particular for a motor vehicle, with a control and / or regulating device for operating the Internal combustion engine. The control and / or regulating device initiates an injection of at least temporarily Fuel into a combustion chamber of the internal combustion engine and an at least temporary supply of air to the Combustion chamber so that the mixture of fuel and air is layered in the combustion chamber in the combustion chamber. The Control and / or regulating device causes ignition of the Fuel-air mixture at a predeterminable time and takes into account when operating the internal combustion engine temperature specific for the internal combustion engine.

State of the art

Direct injection are from the prior art Internal combustion engines known in various Operating modes can be operated. A shift operation is used especially for smaller loads, while a homogeneous operation with larger ones on the internal combustion engine applied loads is applied.

In the homogeneous mode, the fuel during the Intake phase of the engine is injected so that a swirl and thus a distribution of the fuel in the combustion chamber can still be done easily. in this respect homogeneous operation corresponds approximately to the operation of Internal combustion engines in which the fuel is in is conventionally injected into the intake pipe.

In shift operation, the fuel is used during the Compression phase of a cylinder of the internal combustion engine in injected the combustion chamber in such a way that at the time a cloud of fuel in the immediate vicinity the spark plug is located. This causes the fuel-air Mixture enriched so far in the area of the spark plug that there is a safe ignition. The combustion in other combustion chamber takes place on average at strong emaciated fuel-air mixture, i.e. with one significant excess of air instead. Are in the combustion chamber so layers with different fuel-air Ratio available.

From the prior art it is known that the Direct gasoline injection is the injection of fuel into the combustion chambers of the cylinders of the internal combustion engine is defined by the start of injection and the Injection duration. In contrast to the conventional Intake manifold injection plays a role in direct injection The course of the combustion chamber pressure plays a decisive role because the pressure drop when the fuel is injected between a pressure in a high pressure area of a Fuel metering system of the internal combustion engine (with common Rail injection systems referred to as rail pressure) and the Combustion chamber pressure is the one actually injected Determined fuel quantity.

Depending on the operating state, the injection can be within an area from a suction stroke TDC (top dead center) (corresponds to 360 ° KW before TDC) up to an ignition TDC (corresponds to 0 ° KW). Especially during cold starts low temperatures become a large part of this theoretically possible injection range really for Injection used to get the big one needed Bring the amount of fuel into the combustion chambers.

In order to cold start the internal combustion engine, i. H. at low temperatures of the internal combustion engine, ensure a calculated amount of fuel too actually in the combustion chambers of the internal combustion engine arrives, it is known that the start of injection in Dependency on one for the internal combustion engine specific temperature is changed. In this way can be shifted forward by shifting the start of injection the actual amount of fuel injected up and by shifting the start of injection to the rear amount of fuel actually injected down Getting corrected. This can influence the during the injection, especially during a long continuous injection during a cold start End of the compression phase, strongly changing Pressure drop on the actually injected Amount of fuel to be corrected.

From DE 100 40 252 it is known that the Operating behavior of a at low temperatures in Internal combustion engine operated in shifts (e.g. after a cold start) of the operating behavior of a higher temperatures (e.g. at operating temperature) operated internal combustion engine differs significantly. As Cause for the temperature-dependent operating behavior of a That was in the internal combustion engine operated in shifts Evaporation behavior of the fuel in the combustion chamber turned off. In the case of a cold internal combustion engine, too air sucked in and in the combustion chamber relative cold, which is an optimal vaporization of the fuel difficult. The reverse is also true for a warm internal combustion engine the air drawn in is relatively warm, causing the evaporation of the Fuel promotes. Therefore in this publication suggested the pressure in the intake pipe depending on a specific temperature for the internal combustion engine change. The pressure in the intake pipe is preferred by changing at least one cross-section Area of the intake pipe, for example by changing the angle a throttle, changed.

The measures known from the prior art lead to improve the operating behavior of a Internal combustion engine in shift operation at low Temperatures, a further optimization of the However, operational behavior would be desirable.

The present invention is therefore based on the object based on the operating behavior of a in shift operation low temperatures, especially after one Cold start, operated direct injection To further improve the internal combustion engine.

To achieve this object, the invention is based on of the method of the type mentioned above that the Ignition timing depending on the determined Temperature is changed.

Advantages of the invention

Inflammation of the fuel-air mixture in the Combustion chamber at the right time and a complete Burning the fuel is a prerequisite for one operation that saves fuel and avoids emissions the internal combustion engine. According to the invention, it has been recognized that the ignition behavior of the fuel is crucial from the for the internal combustion engine specific temperature and dependent mixture preparation. It was further recognized that the effects of a low temperatures of the internal combustion engine changed Mixture preparation for the operating behavior of a Internal combustion engine in shift operation temperature-dependent variation of the ignition timing can be compensated.

The ignition properties of the fuel depend on the Temperature down: At low temperatures, i.e. H. at cold Internal combustion engine and cold fuel, one optimal ignition of the fuel difficult. Are reversed higher temperatures, d. H. a warm internal combustion engine and warm fuel that promotes ignition of the fuel.

The ignitability of the fuel-air mixture and the complete combustion of the fuel in the combustion chamber an internal combustion engine is not just about the temperature, but also dependent on the ignition timing. The leaner that Air-fuel mixture, i. H. the bigger the There is excess air, the longer the ignition takes of the fuel-air mixture and the further the Ignition timing can be shifted to early times. Conversely, at a high specific temperature Internal combustion engine the ignition timing at later Points in time are shifted without this Operating behavior of the internal combustion engine deteriorates because the mixture becomes richer at higher temperatures and the excess air decreases. The invention Measure the ignition timing depending on the determined So changing temperature makes it possible in everyone Temperature range of the internal combustion engine for one optimal ignition of the fuel-air mixture and for a complete combustion of the fuel to provide the required ignition timing.

The measure according to the invention, among others, the Smooth running of the internal combustion engine in the cold operating state improved. In addition, fewer pollutants are emitted and reduces noise. In addition arise higher exhaust gas temperatures required for heating a Pre-catalyst are advantageous.

According to an advantageous development of the present Invention it is proposed that the air the combustion chamber is fed via an intake pipe and the pressure in the Intake pipe depending on the determined temperature is changed. The temperature dependent variation of the Pressure in the intake pipe is per se from DE 100 40 252 known. Together with the method according to the invention results from the operation of an internal combustion engine in Shift operation, especially at low temperatures, an even combustion and an optimal one Performance.

According to a preferred embodiment of the present Invention is proposed to be a start of Fuel injection depending on the determined Temperature is changed. The temperature dependent Variation of the start of injection is also in itself known in the art. In combination with one or more of the above measures can be an optimal Operating behavior of an internal combustion engine in the Shift operation, especially at low temperatures, be achieved.

To determine the specific for the internal combustion engine Media are particularly suitable for use during the Operation of the internal combustion engine through this or be directed past this. A is therefore advantageous inventive method in which as specific Temperature the temperature of one during operation of the Internal combustion engine heated medium, in particular Cooling water, cooling air and / or engine oil is determined. The Temperature of this media is in a range that with relatively inexpensive sensors can be detected. About that in addition, these media react relatively quickly Changes in the temperature of the internal combustion engine, e.g. B. of the engine block, so that the actual Temperature of the internal combustion engine without great delay can be determined.

According to a further preferred embodiment of the The present invention proposes that the compared the determined temperature with a threshold value and the ignition point when the temperature falls below the Threshold is shifted to earlier times. This measure, for example, shortly after starting the Internal combustion engine if its specific temperature is still is relatively low (cold start), the operating behavior in the Shift operation significantly improved.

Furthermore, it is proposed according to the invention that the compared the determined temperature with a threshold value and the ignition point when the threshold value is exceeded is shifted to later times. This will ensures that the ignition timing of the Internal combustion engine again at later times is shifted as soon as it reaches its normal operating temperature, which is in the range of 95 ° C to 105 ° C, in order to operate an internal combustion engine Direct fuel injection achievable in shift operation Advantages such as minimizing the Fuel consumption and damage remissions, to be able to maximize.

The realization of the inventive method in the form of a Storage element that for a control and / or regulating device an internal combustion engine, in particular for a Motor vehicle is provided. It is on the Memory element a computer program stored on a computing device, in particular on a microprocessor, executable and for executing the invention Process is suitable. In this case, the Invention by a stored on the memory element Computer program realized so that this with the Computer program provided memory element in the same The invention represents how the method for its Execution the computer program is suitable. As Storage element can in particular be an electrical one Storage medium are used, e.g. a read-only Memory, a random access memory or a flash memory.

The invention also relates to a computer program for Execution of the method according to the invention is suitable, if it is on a computing device, especially on a Microprocessor, expires. It is particularly preferred if the computer program is on a storage element, is stored in particular on a flash memory. As a further solution to the problem of the present Invention is based on the tax and / or Control device of the type mentioned suggested that the control and / or regulating device for Internal combustion engine specific temperature at the Determination of the ignition timing taken into account.

Finally, the task is solved yet another of the present invention based on the Internal combustion engine of the type mentioned proposed that the control and / or regulating device for the internal combustion engine specific temperature at the Determination of the ignition timing taken into account.

drawings

Other features, applications and advantages of Invention result from the following description of embodiments of the invention, which in the Drawing are shown. Thereby form all described or illustrated features for themselves or in any Combination the subject of the invention, regardless of their summary in the claims or their Relationship and regardless of their wording or Representation in the description or in the drawing. It demonstrate:

Fig. 1, an internal combustion engine according to the invention according to a preferred embodiment; and

FIG. 2 shows a schematic flow diagram of a method according to the invention for operating the internal combustion engine from FIG. 1 according to a preferred embodiment.

Description of the embodiments

In Fig. 1, an internal combustion engine according to the invention is indicated in its entirety by reference numeral 1. A piston 2 can be moved back and forth in a cylinder 3 of the internal combustion engine 1 . The cylinder 3 is provided with a combustion chamber 4 which is delimited inter alia by the piston 2 , an inlet valve 5 and an outlet valve 6 . An intake pipe 7 is coupled to the inlet valve 5 and an exhaust pipe 8 is coupled to the outlet valve 6 .

In the area of the inlet valve 5 and the outlet valve 6, an injection valve 9 and a spark plug 10 protrude into the combustion chamber 4 . Fuel can be injected into the combustion chamber 4 via the injection valve 9 . Via the inlet valve 5 to the combustion chamber 4 can 7 air are supplied via the intake pipe. The mixture of fuel and air in the combustion chamber 4 can be ignited with the spark plug 10 .

In the intake pipe 7 , a rotatable throttle valve 11 is accommodated, via which air can be supplied to the intake pipe 7 . The amount of air supplied is dependent on the angular position of the throttle valve 11 . A catalytic converter 12 is accommodated in the exhaust pipe 8 and serves to clean the exhaust gases resulting from the combustion of the fuel in the combustion chamber 4 .

The internal combustion engine 1 comprises a cooling water circuit 21 , which is arranged around the cylinder 3 as an example in FIG. 1. The temperature of the coolant in the cooling water circuit 21 is detected by a temperature sensor 22 . The temperature of the coolant is an accurate and reliable indicator of the specific temperature T _{mot of} the internal combustion engine 1 . To determine the specific temperature T _{mot of} the internal combustion engine 1 , other media can be used that are heated during the operation of the internal combustion engine 1 , in particular cooling air and / or engine oil.

A control and / or regulating device for operating the internal combustion engine 1 is designated by the reference symbol 18 . The control and / or regulating device 18 is acted upon by input signals 19 , which represent operating variables of the internal combustion engine 1 measured by sensors. Among other things, the control and / or regulating device 18 is supplied with the temperature T _mot specific for the internal combustion engine 1 , which temperature is determined by the temperature sensor 22 . The control and / or regulating device 18 generates output signals 20 with which the behavior of the internal combustion engine 1 can be influenced via actuators or actuators. For example. the control and / or regulating device 18 is connected to the injection valve 9 , the spark plug 10 , the throttle valve 11 and the like and generates the control signals required for their control. The control signal for controlling the spark plug 10 is denoted by t _ignition .

Among other things, the control and / or regulating device 18 is provided to control and / or regulate the operating variables of the internal combustion engine 1 . For example. the amount of fuel injected by the injection valve 9 into the combustion chamber 4 is controlled and / or regulated by the control and / or regulating device 18, in particular with regard to low fuel consumption and / or low pollutant emissions. In addition, the ignition timing is 10 t _ignition of the spark plug of the control and / or regulating unit 18 with respect to an optimum ignition of the fuel-air mixture and a complete combustion of the fuel in the combustion chamber 4 is controlled and / or regulated.

To control and / or regulate the operating variables, the control and / or regulating device 18 is provided with a memory element 23 , which is, for example, in the form of a flash memory and on which a computer program is stored which is suitable for the control and / or carry out regulation. The control and / or regulating device 18 also has a microprocessor 24 on which the computer program for executing the control and / or regulating function runs. To run the computer program on the microprocessor 24 , either the entire computer program or individual commands of the computer program are transmitted from the memory element 23 to the microprocessor 24 via a data transmission connection 25 .

FIG. 2 shows a schematic flow diagram of a method according to the invention for operating the internal combustion engine 1 from FIG. 1 according to a preferred embodiment. The method is carried out when the internal combustion engine 1 is operated in shift operation and has not yet reached its operating temperature (depending on the design, about 95 ° C. to 105 ° C.). An internal combustion engine 1 is usually started in homogeneous operation. From an engine temperature of around 60 ° C, the system switches to shift operation. At these relatively low specific temperatures T _{mot of} the internal combustion engine 1 , however, uniform combustion and a stable operating state can hardly be achieved. The method according to the invention is intended to remedy this.

The method shown in FIG. 2 is carried out in the control and / or regulating device 18 . From the temperature T _mot determined for the internal combustion engine 1 by the temperature sensor 22, a correction _value t _corr for the ignition point is determined with the aid of a characteristic diagram 30 . In the map 30 information is stored, after which the ignition timing t _ignition at low specific temperatures T _mot, eg. After a cold start, is displaced at earlier times out (t _zünd <t _'zünd). Conversely, the ignition timing is t _flammable at higher temperatures specific T _mot, eg. At operating temperature, shifted to later time points back (t _zünd> t _'flammable).

That of the control and / or regulating device 18 value determined in a conventional manner for the ignition timing t 'usual mathematical operations in a function block 31 is _flammable in the frame by means of the correction value corrected t _corr. The mathematical operations comprise, in particular an addition or multiplication of the correction value _corr t t with the initially determined value _'ignition for the ignition timing. The function of the specific temperature T of the engine 1 _mot corrected value for the ignition timing t _zünd is then used for controlling the spark plug 10 degrees.

In addition to the temperature-dependent variation of the ignition timing t _ignition, the pressure in the intake manifold 7 may vary depending upon the specific temperature T _mot by corresponding activation of the injection valve 9 of the internal combustion engine 1 can be varied by changing the angular position of the throttle valve 11 and the initiation of fuel injection.

Claims (11)

1.Method for operating a direct-injection internal combustion engine ( 1 ), in particular for a motor vehicle, in which fuel is at least temporarily injected into at least one combustion chamber ( 4 ) of the internal combustion engine ( 1 ) and air is supplied to the combustion chamber ( 4 ) at least temporarily in such a way that wherein the fuel-air mixture is ignited at a predetermined point in time (t_zünd) and in which is specific for the internal combustion engine (1) temperature (T_MOT) is determined is layered mixture of fuel and air in the combustion chamber (4), characterized characterized in that the ignition timing (t_ Zünd) is changed depending on the determined temperature (T_mot). 2. The method according to claim 1, characterized in that the air is supplied to the combustion chamber ( 4 ) via an intake pipe ( 7 ) and the pressure in the intake pipe ( 7 ) is changed as a function of the temperature (T_mot) determined. 3. The method according to claim 1 or 2, characterized characterized that a start of fuel injection depending on the determined temperature (T_mot) is changed. 4. The method according to any one of claims 1 to 3, characterized in that the specific temperature (T_mot) is the temperature of a medium heated during operation of the internal combustion engine ( 1 ), in particular of cooling water, cooling air and / or engine oil. 5. The method according to any one of claims 1 to 4, characterized characterized that the determined temperature (T_mot) with compared to a threshold value and the ignition point (t_ Zünd) if the threshold value falls below previous levels Points in time is shifted. 6. The method according to any one of claims 1 to 5, characterized characterized that the determined temperature (T_mot) with compared to a threshold value and the ignition point (t_ Zünd) if the threshold is exceeded at a later time Points in time is shifted. 7. Memory element ( 23 ), in particular read-only memory, random access memory or flash memory, for a control and / or regulating device ( 18 ) of an internal combustion engine ( 1 ), in particular for a motor vehicle, on which a computer program is stored is executable on a computing device, in particular on a microprocessor ( 24 ), and is suitable for executing a method according to one of claims 1 to 6. 8. Computer program that is executable on a computing device, in particular on a microprocessor ( 24 ), characterized in that the computer program is suitable for executing a method according to one of claims 1 to 6 when it runs on the computing device. 9. Computer program according to claim 8, characterized in that the computer program is stored on a memory element ( 23 ), in particular on a flash memory. 10. Control and / or regulating device ( 18 ) for operating an internal combustion engine ( 1 ), in particular for a motor vehicle, the control and / or regulating device ( 18 ) at least temporarily injecting fuel into a combustion chamber ( 4 ) of the internal combustion engine ( 1 ) and an at least temporary supply of air into the combustion chamber ( 4 ) in such a way that the mixture of fuel and air is stratified in the combustion chamber ( 4 ), and the control and / or regulating device ( 18 ) ignites the fuel-air solvent mixture causes a predeterminable point in time (t_zünd), wherein the control and / or regulating device (18) takes account of a specific for the internal combustion engine (1) temperature (T_MOT) during operation of the internal combustion engine (1), characterized in that the control and / or regulating device (18) specific to the internal combustion engine (1) temperature (T_MOT) included in the calculation of the ignition timing (t_zünd). 11. Internal combustion engine ( 1 ), in particular for a motor vehicle, with a control and / or regulating device ( 18 ) for operating the internal combustion engine ( 1 ), the control and / or regulating device ( 18 ) at least temporarily injecting fuel into a combustion chamber ( 4 ) of the internal combustion engine ( 1 ) and an at least temporary supply of air into the combustion chamber ( 4 ) in such a way that the mixture of fuel and air is stratified in the combustion chamber ( 4 ), and the control and / or regulating device ( 18 ) ignition of the fuel-air mixture to a predeterminable time (t_zünd) causes, wherein the control and / or regulating device (18 a considered) during operation of the internal combustion engine (1) for the internal combustion engine (1) specific temperature (T_MOT) characterized in that the controlling and / or regulating device (18) takes account of the specific for the internal combustion engine (1) temperature (T_MOT) in the determination of the ignition timing (t_zünd) ,