WO2003008775A1

WO2003008775A1 - Method, computer programme, control and/or regulating device for operating an internal combustion engine and internal combustion engine

Info

Publication number: WO2003008775A1
Application number: PCT/DE2002/002537
Authority: WO
Inventors: Roland Herynek; Martin Vollmer
Original assignee: Robert Bosch Gmbh
Priority date: 2001-07-18
Filing date: 2002-07-11
Publication date: 2003-01-30
Also published as: DE10135057A1

Abstract

In an internal combustion engine comprising direct injection, at least one portion of the fuel can be injected into a combustion chamber of the internal combustion engine in such a way that said fuel is stratified. A wall, which delimits at least some sections of the combustion chamber is cooled by a coolant that traverses at least some sections of the wall. The aim of the invention is to operate the internal combustion engine with optimal emissions and an optimal consumption rate and to produce said engine cost-effectively. To achieve this, the coolant is transported by an electrically driven coolant pump and the speed (ncp) of the coolant pump is dependent on at least one operating variable (nmot, TZYL, TCF) of the internal combustion engine.

Description

Method, computer program, control and / or reqel device for operating an internal combustion engine and internal combustion engine

State of the art

The invention relates first of all to a method for operating an internal combustion engine with direct injection, in which at least part of the fuel can be injected into a combustion chamber of the internal combustion engine in such a way that it is stratified there, and in which the cooling of a wall that delimits the combustion chamber at least in regions by means of Coolant takes place, which flows through the wall at least in regions.

Such a method is known from EP 0 887 526 A2. In the internal combustion engine shown there, the fuel is injected directly into the combustion chambers of the internal combustion engine by injectors. The internal combustion engine can work either in shift operation or in homogeneous operation. In stratified operation, the fuel is injected into the combustion chamber in such a way that an ignitable fuel-air mixture is only present in the area of the spark plug, whereas there is little or no fuel in the remaining area of the combustion chamber. In contrast, in homogeneous operation the fuel is distributed essentially homogeneously throughout the combustion chamber.

In the known method, the cylinders of the A coolant flows through the internal combustion engine, which is required by a coolant pump. The coolant flow can be adjusted by means of several control valves so that the cylinder is cooled less strongly in the stratified operation of the internal combustion engine, whereas it is cooled more strongly in the homogeneous operation.

This procedure is based on the consideration that the combustion chamber walls are less heated by the combustion gases in stratified operation than in homogeneous operation. This depends, among other things. together with the fact that the maximum temperatures occur in shift operation in the area of the spark plug. However, excessive cooling of the combustion chamber wall worsens the ignition behavior and makes it more difficult to atomize the fuel injected by the injector. In addition, it was also found that if the combustion chamber wall is cooled excessively in shift operation, the emission and consumption behavior of the internal combustion engine is not optimal.

The disadvantage of the known method, however, is that an internal combustion engine to be operated according to the method has a complicated construction and relatively extensive control interventions are required for the desired cooling of the cylinders of the internal combustion engine. Furthermore, in the known method, the temperature of the coolant is relatively high, which necessitates high-quality components in the coolant system.

The present invention therefore has the task of developing the above-mentioned method in such a way that the corresponding internal combustion engine can be manufactured more cheaply.

This object is achieved in a method of the type mentioned in the introduction in that the coolant is supplied by a electrically driven coolant pump is promoted and the speed of the coolant pump depends on at least one operating variable of the internal combustion engine.

Advantages of the invention

An internal combustion engine, which is operated according to the method according to the invention, can be constructed simply, since there is no need for complex valve devices for controlling the coolant flow. Such an internal combustion engine can be manufactured inexpensively. In the method according to the invention, the coolant flow is adjusted in that the speed of the coolant pump depends on at least one operating variable of the internal combustion engine. Such an operating variable-dependent setting of the speed of the coolant pump is easily possible since it is electrically driven.

Another advantage of the method according to the invention is that the flow rate of the coolant is influenced by the variable speed of the coolant pump. This in turn leads, at a lower flow rate, to a greater temperature difference between the wall, which at least in some areas delimits the combustion chamber, and the coolant. The advantageous increase in the temperature of the combustion chamber wall under certain circumstances can thus be achieved without an increase in the temperature of the coolant.

The usual inexpensive components can therefore be used for the coolant system. In addition, the cooling capacity can be increased very spontaneously, since in the transition from a low to a higher cooling capacity no previous cooling of an overheated coolant is required. This will change the operating behavior of the Internal combustion engine improved.

Advantageous developments of the invention are specified in the subclaims.

It is proposed that the speed of the coolant pump depends on the operating state of the internal combustion engine. This has the advantage that the temperature of the internal combustion engine or the combustion chamber wall can be adapted to the respective operating state in a simple manner.

In stratified operation, for example, it is advantageous if the temperature of the combustion chamber wall is higher, since this results in better combustion of the fuel, which results in lower fuel consumption. HC and CO raw emissions are also reduced. It is therefore also proposed that the speed of the coolant pump is lower in stratified operation than in homogeneous operation.

The influence of the combustion chamber wall temperature on the emission and consumption behavior of the internal combustion engine is less strong in homogeneous operation than in stratified operation. The coolant pump can therefore be operated in homogeneous mode at a constant speed, which simplifies the control of the coolant pump. In addition, a cheaper coolant pump can be used because the demands on the speed dynamics of the coolant pump are lower.

It is also advantageous if the coolant pump is basically operated at a low speed after starting the internal combustion engine. This enables the optimum temperature of the combustion chamber wall to be reached at an early stage during a cold start, which in turn reduces fuel consumption and emissions. There the temperature of the combustion chamber wall, which is necessary for switching on stratified operation for the first time, is reached relatively early in such a case, the general advantages of stratified operation are made available shortly after the cold start of the internal combustion engine.

Alternatively or in addition to this, it is possible that the speed of the coolant pump depends on the speed of a crankshaft of the internal combustion engine. This is easy to implement in terms of control technology.

Again, additionally or alternatively, the speed of the coolant pump can also depend on the temperature of the coolant. This is also easy to implement using a temperature sensor.

The same also applies to that development of the method according to the invention in which the speed of the coolant pump depends on the temperature of at least one area of the combustion chamber wall.

In both of the aforementioned cases, it is particularly preferred if a setpoint speed of the coolant pump is determined via a characteristic curve or a characteristic diagram. Such a characteristic curve or such a characteristic diagram are easy to program and allow the consideration of several operating variables. In this way, the optimal speed of the coolant pump is always specified in a simple manner.

The invention also relates to a computer program which is suitable for carrying out the above method when it is executed on a computer. It is particularly preferred if it is stored on a memory, in particular on a flash / memory. The invention further relates to a control and / or regulating device for operating an internal combustion engine. In order to be able to operate the internal combustion engine optimally and at the same time to produce it inexpensively, it is proposed that the control and / or regulating device comprise a memory on which a computer program of the above type is stored.

Furthermore, the invention relates to an internal combustion engine, with a Kraf material injection device, which is arranged so that it can inject fuel directly into the combustion chamber so that it is stratified there, with a coolant pump and with a coolant line, which at least in the combustion chamber area-bounding wall is present.

In order to operate such an internal combustion engine with optimum emissions and consumption and at the same time to produce it inexpensively, it is proposed that the coolant pump be connected to and driven by an electric motor and that its speed can be set as a function of at least one operating variable of the internal combustion engine.

It is particularly preferred if the coolant pump is connected to a control and / or regulating device of the above type.

drawing

Below is a particularly preferred one

Embodiment of the invention explained in detail with reference to the accompanying drawings. The drawing shows:

Figure 1 is a schematic representation of an internal combustion engine; FIG. 2 is a diagram in which, in each case over time, the operating mode, the speed of a crankshaft, the speed of a coolant pump and a coolant flow of the internal combustion engine from FIG. 1 are plotted; and

Figure 3 is a flowchart showing the mode-dependent control of the coolant pump of the internal combustion engine of Figure 1.

Description of the embodiment

In FIG. 1, an internal combustion engine bears the reference number 10 overall. It comprises several cylinders, only one of which is shown in FIG. 1 and bears the reference number 12. A piston 14 is guided in the cylinder 12. This works on a crankshaft 16, the speed of which is detected by a speed sensor 17. A combustion chamber 18 is present in FIG. 1 above the piston 14. This is delimited radially by a wall 20 and upwards in FIG. 1 by a cylinder head 22.

The wall 20 and the cylinder head 22 are penetrated by coolant lines 24. Fuel is injected into the combustion chamber -18 directly by an injector 26 arranged in the cylinder head 22. The injected fuel is ignited by a spark plug 28. The temperature of the cylinder head 22 is detected by a temperature sensor 30.

Combustion air is supplied to the combustion chamber 18 through an inlet pipe 32. This is connected to the combustion chamber 18 via an inlet valve, not shown. A throttle valve 34 is arranged in the inlet pipe 32 and can be moved by a servomotor 36. The through that The amount of air entering the combustion chamber 18 into the combustion chamber 18 is measured by a hot film sensor (“HFM sensor”) 38.

The combustion exhaust gases are passed from the combustion chamber 18 into an exhaust pipe 40. This is connected to the combustion chamber 18 via an exhaust valve, not shown. A catalytic converter 42 is present in the exhaust pipe 40. A lambda probe 44 detects the mixture composition.

The coolant lines 24 in the wall 20 and in the cylinder head 22 are connected on the inlet side to a cooler 46 and also to a coolant pump 48. This is driven by an electric motor 50. The temperature of the coolant is detected by a temperature sensor 52.

Fuel is supplied to injector 26 from a fuel system 54. This includes several components, not shown in FIG. 1, such as a fuel tank, a pre-delivery and a main delivery pump, as well as a fuel manifold ("rail") in which the fuel is stored under high pressure and to which the injector is in turn 26 is connected. The spark plug 28 is in turn connected to an ignition system 56, which provides the energy required for ignition.

The internal combustion engine 10 also includes a control and regulating device 58. Various functions of the internal combustion engine 10 are controlled and regulated with it. For this purpose, the control and regulating device is on the input side with the temperature sensor 30 on the cylinder head 22, with the speed sensor 17 on the crankshaft 16, with the lambda sensor 44 in the exhaust pipe 40, with the HFM sensor 38 in the inlet pipe 32, with the temperature sensor 52 in Area of the cooler 46, and connected to a position transmitter 60 of an accelerator pedal 62. The control unit is on the output side 58 signals connected to the electric motor 50, which drives the coolant pump 48, the servomotor 36, which adjusts the throttle valve 34, the ignition system 56 and the injector 26.

The operation of the internal combustion engine 10 will now be explained with reference to FIGS. 2 and 3:

The injector 26 is arranged and the combustion chamber 18 is designed such that, depending on the point in time at which the injector 26 injects fuel into the combustion chamber 18, the fuel in the combustion chamber 18 is stratified or homogeneous. In the event that the fuel is stratified in the combustion chamber ("stratified operation"), fuel is essentially only present in the area of the spark plug 28, whereas there is little or no fuel in the rest of the combustion chamber 18. In shift operation, the internal combustion engine mainly works at idle and at partial load.

If the fuel is distributed homogeneously in the combustion chamber 18 (“homogeneous operation”), an ignitable mixture is essentially present in the entire combustion chamber 18. This operating mode is mainly selected at full load and high speeds. Combined operation of the internal combustion engine 10 is also possible, in which, for example, initially during a work cycle; a homogeneous injection followed by a stratified injection.

In shift operation of the internal combustion engine 10 in particular, it is advantageous if the wall 20 and the cylinder head 22 of the internal combustion engine 10 are at a high temperature. As can be seen from FIG. 2, this is achieved in that the speed ncp of the coolant pump during the stratified operation of the internal combustion engine 10 48 is kept relatively low. Thus, the coolant flow dmcp / dt flowing through the coolant lines 24 is also slow, so that only comparatively little heat is transferred from the wall 20 or the cylinder head 22 to the coolant flowing in the coolant lines 24.

As can also be seen from FIG. 2, the speed ncp of the coolant pump 48 is kept particularly low immediately after the start of the internal combustion engine 10 in order to enable rapid heating of the wall 20 and the cylinder head 22 of the internal combustion engine 10. The period in which the rotational speed ncp of the coolant pump 48 is kept so low is identified in FIG. 2 by the reference number 64.

After this period 64, the speed ncp of the coolant pump 48 is set as a function of the speed nmot of the crankshaft 16 of the internal combustion engine 10, as well as depending on the cylinder head temperature determined by the temperature sensor 30 and the coolant temperature determined by the temperature sensor 52. For this purpose, a map is stored in the control and regulating device 58, which generates a setpoint for the speed ncp of the coolant pump 48 as a function of the said operating variables. In homogeneous operation, that is, at higher speeds nmot of the internal combustion engine 10, the coolant pump 48 is operated at a constant and comparatively high speed.

The coolant pump 48 is activated according to a method which is stored as a computer program in the control and regulating device 58 (cf. FIG. 3). After a start block 66, it is checked in a block 68 which operating mode the internal combustion engine 10 is operated in. This depends, among other things, on the rotational speed nmot of the crankshaft 16 and on the torque request which is sent by the position transmitter 60 Accelerator pedal 62 is tapped.

If the internal combustion engine 10 is in the “shift” operating mode, a query is made in block 70 as to whether the temperature TZYL of the cylinder head 22, which is detected by the temperature sensor 30, has exceeded a limit value G. If this is not the case, the speed ncp of the coolant pump 48 is determined in a map in block 72, which includes the speed nmot of the crankshaft 16, the temperature TZYL of the cylinder head 22 and the temperature TCF of the coolant as operating variables.

If, on the other hand, it is determined in block 70 that the temperature TZYL of the cylinder head 22 has already exceeded the limit value G, the speed ncp of the coolant pump 48 is set to a constant value C1 in block 74. At this speed, it is ensured in any case that the cylinder 12 is cooled to such an extent that no damage occurs to it.

If it is determined in block 68 that the internal combustion engine 10 is not operating in stratified mode, but that the "homogeneous" operating mode is present, the speed ncp of the coolant pump 48 is set to a constant value C2 in block 76. The program ends in an end block 78.

Claims

Expectations

1. Method for operating an internal combustion engine (10) with direct injection, in which at least part of the fuel can be injected into a combustion chamber (18) of the internal combustion engine (10) in such a way that it is stratified there, and in which the combustion chamber is cooled (18) at least in some areas bounding wall (20, 22) by a coolant which flows through the wall (20, 22) at least in areas, characterized in that the coolant is conveyed by an electrically driven coolant pump (48) and the speed (ncp ) the coolant pump (48) depends on at least one operating variable (layer, homogeneous, nmot, TZYL, TCF) of the internal combustion engine (10).

2. The method according to claim 1, characterized in that the speed (ncp) of the coolant pump (48) depends on the operating state (layer, homogeneous) of the internal combustion engine.

3. The method according to claim 2, characterized in that the speed (ncp) of the coolant pump (48) in shift operation (shift) is lower than in homogeneous operation (homogeneous).

4. The method according to any one of claims 2 or 3, characterized in that the coolant pump (48) in homogeneous operation (homogeneous) with constant speed (C2) is operated.

5. The method according to any one of claims 2 to 4, characterized in that the coolant pump (48) is basically operated at low speed (ncp) after starting the internal combustion engine (10).

6. The method according to any one of the preceding claims, characterized in that the speed (ncp) of the coolant pump (48) depends on the speed (nmot) of a crankshaft (16) of the internal combustion engine (10).

7. The method according to any one of the preceding claims, characterized in that the speed (ncp) of the coolant pump (48) depends on the temperature (TCF) of the coolant.

8. The method according to any one of the preceding claims, characterized in that the speed (ncp) of the coolant pump (48) depends on the temperature (TZYL) of at least one area (22) of the combustion chamber wall.

9. The method according to any one of claims 7 or 8, characterized in that a target speed (nscp) of the coolant pump (48) via a characteristic curve or a map

(72) is determined.

10. Computer program, characterized in that it is suitable for carrying out the method according to one of the preceding claims when it is executed on a computer.

11. Computer program according to claim 10, characterized in that it is stored on a memory, in particular on a flash memory.

12. Control and / or regulating device (58) for operating an internal combustion engine (10), characterized in that it comprises a memory on which a computer program according to one of claims 10 or 11 is stored.

13. Internal combustion engine (10), with a fuel injection device (26) which is arranged so that it can inject fuel directly into the combustion chamber (18) so that it is stratified there, with a coolant pump (48), and with a coolant line (24) which is present in a wall (20, 22) delimiting the combustion chamber (18) at least in some areas, characterized in that the coolant pump (48) is connected to and driven by an electric motor (50), and in that their speed (nmot) as a function of at least one operating variable (layer, homogeneous, nmot,

'TZYL, TCF) of the internal combustion engine (10) can be set.

14. Internal combustion engine (10) according to claim 13, characterized in that the coolant pump (48) is connected to a control and / or regulating device (58) according to claim 12.