WO2006111438A1

WO2006111438A1 - Method and device for controlling an internal combustion engine

Info

Publication number: WO2006111438A1
Application number: PCT/EP2006/060480
Authority: WO
Inventors: Gerhard Eser; Hong Zhang
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-04-20
Filing date: 2006-03-06
Publication date: 2006-10-26
Also published as: DE102005018320A1

Abstract

The invention relates to an internal combustion engine comprising a spark plug and a fuel supply device to which an injection valve is actively connected. A fuel mass (MFF) to be measured is determined according to at least one operating variable of the internal combustion engine, and the injection valve is controlled accordingly. An advance angle (IGN) is determined according to the pressure (FUP) of the fuel in the supply device, and the spark plug is controlled accordingly. Part of the injection angle can be determined according to the fuel mass (MFF) to be measured, while the fuel passing through the injection valve is measured, and an angle which is characteristic of the position of the part of the injection angle is determined according to the pressure (FUP) of the fuel in the supply device, and the injection valve is controlled accordingly.

Description

description

Method and device for controlling an internal combustion engine

The invention relates to a method and a device for controlling an internal combustion engine.

There are known internal combustion engines with an intake manifold, one or more cylinders, a supply device for fuel and each of the cylinders associated injectors, which are operatively connected to the supply device for fuel. The injectors are either located in intake manifolds that are part of the intake tract and are guided toward intake of the cylinders, or the injectors are located directly in the cylinder head and meter the fuel directly into the combustion chamber of the cylinders of the internal combustion engine. The injection valves are increasingly subjected to very high fuel pressures, which can reach in the case of internal combustion engines with gasoline as fuel up to 200 bar. In addition, for injectors as an actuator of the electromagnetic actuator is increasingly replaced by piezoelectric actuators. Piezoelectric actuators have u. a. the advantage that the injection valve can be operated with a variable valve lift of the nozzle needle.

Increasingly stringent legislation on pollutant emissions make it necessary to keep the pollutant emissions as low as possible during operation of the internal combustion engine. In addition, internal combustion engines should be very powerful and have low fuel consumption.

The object of the invention is to provide a method and a device which enables an efficient operation of the internal combustion engine. The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized according to a first aspect by a method and a corresponding device for controlling an internal combustion engine with a supply device for fuel, with which an injection valve is operatively connected, and with a spark plug. A metered fuel mass is determined depending on at least one operating variable of the internal combustion engine and the injection valve is driven accordingly. An ignition angle is determined depending on the fuel pressure of the fuel in the feeder, and the spark plug is driven accordingly.

According to a second aspect, the invention is characterized by a method and a corresponding device for controlling the internal combustion engine, in which the fuel mass to be metered is determined as a function of at least one operating variable of the internal combustion engine, an injection angle range during which fuel is to be metered by the injection valve is determined by the fuel mass to be metered and a characteristic of the position of the injection angle range angle is determined depending on the fuel pressure of the fuel in the feeder and the injection valve is driven accordingly. The angle that is characteristic of the position of the injection angle range can be, for example, an injection start angle or an injection end angle.

The invention is based on the recognition that a mixture preparation of the air / fuel mixture in the respective cylinder depends on a jet penetration depth of fuel metered by the injector and the jet pattern when metering the fuel through the injector. Furthermore, it is also based on the knowledge that the jet penetration depth and the jet pattern are significantly dependent on the fuel pressure in the feed device for fuel. The invention makes use of the finding that, according to the first aspect, the ignition angle is appropriately determined depending on the fuel pressure of the fuel in the feeder, and according to the second aspect, the angle characteristic of the position of the injection angle range depending on the fuel pressure of the fuel in the feeder is determined suitably. In this way, it is easy, for example in a given load point of the internal combustion engine, to achieve a desired uniform mean pressure or a desired low variation coefficient of the mean pressure, independently of a variation of the fuel pressure. In this context, the coefficient of variation refers to the relative change in the mean pressure relative to a respective average mean pressure with a variation of the fuel pressure. Thus, a desired good combustion profile in the context of the combustion of the air / fuel mixture in the respective cylinder of the internal combustion engine can be achieved substantially independently of the fuel pressure.

By combining the first and second aspects of the invention, a particularly high improvement in the desired combustion process can be achieved.

In an advantageous embodiment of the invention, the ignition angle or the characteristic of the position of the injection angle range angle is at least in the operating state of the engine start and / or warm-up dependent determined by the fuel pressure of the fuel in the feeder. In this way, the knowledge is used that the quality of the combustion process very much depends on the spray pattern and the jet penetration depth, especially in the operating states of warm-up and engine start. This has the consequence that a particularly good combustion process can be easily ensured in these very critical operating conditions, especially for pollutant emissions.

According to a further advantageous embodiment of the invention, the ignition angle is determined depending on at least one operating variable of the internal combustion engine. Operating variables of the internal combustion engine are measured variables which are detected by sensors which are assigned to the internal combustion engine and also variables derived from the measured variables. A correction value of the ignition angle is determined as a function of a variable representative of the load on the internal combustion engine and / or a rotational speed of the crankshaft of the internal combustion engine and the fuel pressure of the fuel in the supply device. The ignition angle is corrected depending on the correction value. In this way, a still further improved combustion process can be easily ensured.

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

Figure 1 shows an internal combustion engine with a control device and

Figure 2 is a flowchart of a program for controlling the internal combustion engine. Elements of the same construction and function are identified across the figures with the same reference numerals.

An internal combustion engine (FIG. 1) comprises an intake tract 1, an engine block 2, a cylinder head 3 and an exhaust tract 4. The intake tract 1 preferably comprises a throttle valve 11, furthermore a collector 12 and an intake manifold 13 which leads to a cylinder Z1 via an intake passage is guided in the engine block. The engine block further comprises a crankshaft 21, which is coupled via a connecting rod with the piston 24 of the cylinder Zl.

The cylinder head 3 comprises a valve drive with a gas inlet valve 30 and a gas outlet valve 31. It further comprises an injection valve 34 and a spark plug 35. Alternatively, the injection valve 34 may also be arranged in the intake pipe 13.

Furthermore, a feed device 5 is provided for fuel. It comprises a fuel tank 50, which is connected via a first fuel line to a low-pressure pump 51. On the output side, the low pressure pump 51 is operatively connected to an inlet 53 of a high pressure pump 54. Furthermore, the output side of the low-pressure pump 51, a mechanical regulator 52 is provided, which is connected on the output side via a further fuel line to the tank 50. The inlet 53 is guided to the high-pressure pump 54, which promotes the fuel on the output side to a fuel reservoir 55.

The injection valve 34 is operatively connected to the fuel reservoir 55. The fuel is thus supplied to the injection valve 34 via the fuel reservoir 55.

The injection valves 34 are preferably provided with a piezoelectric actuator. The piezoelectric actuator has Among other things, the advantage that the stroke of the nozzle needle can be variably adjusted by him.

The different beam cones of the fuel exiting from the injection valve 34 are illustrated by the enlarged representations of the injection valve 34 for a pressure value Pl and a pressure value P2 of the fuel pressure FUP. The pressure value Pl is lower than the pressure value P2.

Furthermore, a control device 6 is provided which is associated with sensors which detect different measured variables and in each case determine the measured value of the measured variable. The control device 6 determines dependent on at least one of the measured variables manipulated variables, which are then converted into one or more actuating signals for controlling the actuators by means of corresponding actuators.

The sensors are a pedal position sensor 71 which detects the position of an accelerator pedal 7, 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 detects a crankshaft angle to which a rotational speed N is assigned, another temperature sensor 23 which detects a coolant temperature and a fuel pressure sensor 58 which detects a fuel pressure FUP in the fuel reservoir 55. Depending on the embodiment of the invention may be any subset of said sensors or there may be additional sensors.

The actuators are, for example, the throttle valve 11, the gas inlet and gas outlet valves 30, 31, the injection valve 34 and the spark plug 35. In addition to the cylinder Z1, the internal combustion engine may also include further cylinders Z2-Z4, to which corresponding actuators are then assigned.

A program for controlling the internal combustion engine is started in a step S 1 (FIG. 2) in which variables are initialized if necessary. The start of the program is preferably timely to the engine start of the internal combustion engine.

In a step S2, it is checked whether the internal combustion engine is in an operating state ES of the engine start MS or warm-up. The operating state ES of the engine start MS is preferably assumed as a function of the rotational speed N and the time since the start of the internal combustion engine. The operating state ES of the warm-up WL is preferably assumed when a variable characterizing the operating temperature of the internal combustion engine has not yet reached a predetermined threshold value.

If the condition of step S2 is not fulfilled, the processing is continued in a step S3, in which the program preferably remains for a predefinable waiting period or a predefinable crankshaft angle, before the processing is continued again in step S2.

If, on the other hand, the condition of step S2 is satisfied, then in a step S4 an ignition angle IGN is determined as a function of the rotational speed N and a load variable LOAD. The load variable LOAD may, for example, be an air mass flow in the respective cylinder, but it may also be the intake manifold pressure or a torque to be generated by the internal combustion engine.

The ignition angle is determined, for example, by means of a characteristic field as a function of the rotational speed N and the load size LOAD namely by appropriate interpolation between nodes of the map. The support points of the characteristic field are preferably determined in advance by appropriate tests or simulations. This also applies to the following maps.

In a subsequent step S6, a correction value COR is determined as a function of the fuel pressure FUP, the rotational speed N and the load variable LOAD. This is preferably likewise carried out by means of a characteristic map and corresponding interpolation between the interpolation point values of the characteristic field.

In a step S8, the ignition angle IGN is subsequently corrected as a function of the ignition angle IGN determined in step S4 and the correction value COR.

In a step S10, the fuel mass MFF to be metered is determined as a function of the rotational speed N, the load size LOAD and optionally further operating variables. In this case, the fuel mass MFF to be metered can also be determined in step S10 depending on the fuel pressure FUP.

In a step S12, an injection start angle SOI is subsequently determined as a function of the fuel pressure FUP. For this purpose, a corresponding characteristic curve or a corresponding characteristic field is preferably provided, which is applied in such a way that a variation of an indicated mean pressure caused by changes in the fuel pressure FUP is compensated as well as possible.

In a step S14, an injection end angle EOI is then determined depending on the fuel mass MFF to be metered and the injection start angle SOI. Also in the By means of the injection end angle, the fuel pressure FUP can be taken into account, since it has an influence on the injection angle range which is limited on the one hand by the injection start angle SOI and on the other hand by the injection end angle EOI so as to ensure that the desired fuel mass MFF to be metered is measured. The decisive factor is that the position of the injection angle range is influenced as a function of the fuel pressure by determining the start of injection angle SOI as a function of the fuel pressure. Alternatively, the injection end angle EOI can also be determined as a function of the fuel pressure in step S12, and then the injection start angle is determined in step S14 as a function of the fuel mass MFF to be metered and the injection start angle SOI.

Determining the start of injection angle SOI in step S12 preferably takes place in accordance with step S6 as a function of a suitably applied characteristic curve or a suitably applied characteristic map which is applied in such a way that a variation of the indicated mean pressure is largely compensated.

After determining the ignition angle IGN and / or the injection start angle SOI and / or the injection end angle EOI, the spark plug 35 and the injection valve 34 are driven accordingly. This can be done after the processing of step S14, for example.

Subsequent to step S14, the processing is continued again in step S2.

In a simpler embodiment, the determination of the correction value COR in the step S6 can also be independent of the Speed N and / or the load size LOAD done. In addition, the condition of step S2 can also be dispensed with, and thus also in other operating states ES of the internal combustion engine outside of the engine start MS and the warm-up, the steps S4 to S14 can be carried out. Only at least in the operating states ES of the engine start MS and the warm-up WL is the fuel pressure FUP taken into account when determining the ignition angle IGN and / or the variable representative of the position of the injection angle range.

The angle characteristic of the position of the injection angle range can also be any other angle of the injection angle range in addition to the injection start angle SOI or the injection end angle EOI. Moreover, in a simple embodiment, the program may also only alternatively comprise steps S4, S6, S8 and, secondly, the steps S10, S12 and S14.

Claims

claims

Anspruch [en] A method of controlling an internal combustion engine having a fuel supply device (5) to which an injection valve (34) is operatively connected and having a spark plug (35) in which

a fuel mass to be metered (MFF) is determined as a function of at least one operating variable of the internal combustion engine and the injection valve (34) is actuated accordingly,

- An ignition angle (IGN) is determined depending on the fuel pressure (FUP) of the fuel in the feed device (5) and the spark plug (35) is driven accordingly.

2. The method of claim 1, wherein the ignition angle (IGN) determined at least in an operating state (ES) of the engine start (MS) and / or warm-up (WL) depending on the fuel pressure (FUP) of the fuel in the feed device (5) becomes.

3. The method according to any one of the preceding claims, wherein the ignition angle (IGN) is determined depending on at least one operating variable of the internal combustion engine, a correction value (COR) of the ignition angle (IGN) depending on a representative of the load on the internal combustion engine and / or A rotational speed (N) of the crankshaft (21) of the internal combustion engine and the fuel pressure (FUP) of the fuel in the supply device (5) is determined and the ignition angle (IGN) is corrected in dependence on the correction value (COR).

4. The method according to any one of the preceding claims, in which an injection angle range during which fuel is to be metered by the injection valve (34) is determined as a function of the fuel mass to be metered (FUP) and a characteristic angle for the position of the injection angle range depends on the fuel pressure (FUP) of the fuel in the feed device ( 5) is determined and the injection valve (34) is driven accordingly.

5. The method of claim 4, wherein the characteristic of the position of the injection angle range angle at least in the operating state (ES) of the engine start (MS) and / or warm-up (WL) depending on the fuel pressure (FUP) of the fuel in the feeder ( 5) is determined.

6. A method for controlling an internal combustion engine with a feed device (5) for fuel, with which an injection valve (5) is operatively connected, in which

a metered fuel mass (MFF) is determined as a function of at least one operating variable of the internal combustion engine,

an injection angle range during which fuel is to be metered by the injection valve (34) is determined as a function of the fuel mass to be metered (MFF),

a characteristic angle for the position of the injection angle range is determined as a function of the fuel pressure (FUP) of the fuel in the feed device (5), and

- The injection valve (34) is driven accordingly.

7. The method of claim 6, wherein the characteristic of the position of the injection angle range angle at least in the operating state (ES) of the engine start (MS) and / or the warm-up (WL) depending on the Fuel pressure (FUP) of the fuel in the feeder (5) is determined.

8. An apparatus for controlling an internal combustion engine with a feed device (5) for fuel, with which an injection valve (34) is operatively connected and with a spark plug (35) which is adapted to

Determining a fuel mass to be metered (MFF) as a function of at least one operating variable of the internal combustion engine,

- corresponding actuation of the injection valve (34),

- Determining a firing angle (IGN) depending on the fuel pressure (FUP) of the fuel in the feeder (5) and

- Appropriate activation of the spark plug (35).

9. An apparatus for controlling an internal combustion engine with a feed device (5) for fuel, with which an injection valve (5) is operatively connected, which is designed for

Determining an injection angle range during which fuel is to be metered by the injection valve (34), depending on the fuel mass to be metered (MFF),

- Determining a characteristic of the position of the injection angle range angle depending on the fuel pressure (FUP) of the fuel in the feed device (5) and

- Appropriate driving of the injection valve (34).