METHOD AND SYSTEM FOR CONTROL OF A FORCED INDUCTION SYSTEM

Abstract

In a method for the control of a supercharge system with several turbine wheels, each of which is arranged in an exhaust conduit from cylinders in a combustion engine, different from the cylinders in whose exhaust conduits the one or several other turbine wheels are arranged, wherein the turbine wheels are arranged to each operate a compressor wheel, arranged in an air inlet conduit to the combustion engine, a value for the rotational speed of the respective turbine wheels is determined, and the rotational speed of the respective turbine wheels is controlled by way of impacting the fuel injection into those cylinders, whose exhaust conduit is connected with the turbine wheel.

Claims

1. A method for control of a supercharge system with a number of turbine wheels, each of which is arranged in an exhaust conduit, from cylinders in a combustion engine, different from the cylinders in whose exhaust conduits the one or several other turbine wheels are arranged, wherein the turbine wheels are arranged to each operate a compressor wheel, arranged in an air inlet conduit to the combustion engine, wherein the method comprises the steps of: determining a value for the rotational speed of the respective turbine wheels; and controlling the rotational speed of the respective turbine wheels depending on said determined speed, by impacting the fuel injection into those cylinders, whose exhaust conduit is connected with a respective turbine wheel.

2. A method according to claim 1 further comprising comparing said determined values for the rotational speed of the turbine wheels with set-point values for these, and said controlling the rotational speed comprises impacting said fuel injection into the cylinders based on the result of such comparison.

3. A method according to claim 2, wherein impacting the fuel injection comprises impacting the fuel injection into the cylinders associated with the respective turbine wheels to control the rotational speed of the turbine wheel towards a set-point value in the form of an optimal working speed for the compressor wheel, connected with the turbine wheel.

4. A method according to claim 2, wherein impacting the fuel injection comprises impacting the fuel injection into the cylinders associated with the respective turbine wheels to control the rotational speed of the turbine wheel towards a working speed of the associated compressor wheels, located at a predetermined distance from the rotational speed of the compressor wheels' pumping limit, or within a predetermined distance interval from the rotational speed of the compressor wheels' pumping limit.

5. A method according to claim 1, wherein impacting the fuel injection comprises impacting the fuel injection into the cylinders to balance the workload/speed of the various turbine wheels with each other.

6. A method according to claim 1, wherein impacting the fuel injection comprises impacting the fuel injection into the cylinders for control of the rotational speed of the turbine wheels towards one and the same value.

7. A method according to claim 1, wherein the control of the rotational speed of the respective turbine wheels is carried out by controlling the amount of fuel injected into the cylinders associated with the turbine wheel.

8. A method according to claim 1 comprising control of the rotational speed of the respective turbine wheels by controlling post-injections of fuel into cylinders associated with the turbine wheel following the combustion occurring in the respective cylinder, with the objective of impacting the cylinder's piston, in order to impact the pressure of exhaust pulses and the temperature of exhausts from the cylinder.

9. A method according to claim 1 comprising control of the rotational speed of the respective turbine wheels by controlling the timing of fuel injections into the cylinders associated with the turbine wheel.

10. A system for control of a supercharge system with several turbine wheels, each of which is arranged in an exhaust conduit from cylinders in a combustion engine, different from the cylinders in whose exhaust conduits the one or several other turbine wheels are arranged, wherein the turbine wheels are arranged to each operate one compressor wheel, arranged in an air inlet conduit to the combustion engine, said system comprising: means adapted to determine a value of the rotational speed in the respective turbine wheels; and a device adapted to control the rotational speed of the turbine wheels depending on information from said means about speed values determined thereby, wherein that the device is adapted to control the speed of the respective turbine wheels by impacting the fuel injection into those cylinders, whose exhaust conduit is connected with a respective turbine wheel.

11. A system according to claim 10 further comprising, a device adapted to compare determined rotational speed values for the turbine wheels with set-point values for these, and to control the device to carry out said control based on the result of such comparison.

12. (canceled)

13. A computer program product comprising computer program code stored on a non-transitory computer-readable medium, which is readable by a computer, said computer program product used for control of a supercharge system with several turbine wheels, each of which is arranged in an exhaust conduit from cylinders in a combustion engine, different from the cylinders in whose exhaust conduits the one or several other turbine wheels are arranged, wherein the turbine wheels are arranged to each operate one compressor wheel, arranged in an air inlet conduit to the combustion engine, said computer program code comprising computer instructions to cause one or more computer processors to perform the operations of: determining a value for the rotational speed of the respective turbine wheels; and controlling the rotational speed of the respective turbine wheels depending on said determined speed, by impacting the fuel injection into those cylinders, whose exhaust conduit is connected with a respective turbine wheel.

14. An electronic control device for control of a supercharge system with several turbine wheels, each of which is arranged in an exhaust conduit from cylinders in a combustion engine, different from the cylinders in whose exhaust conduits the one or several other turbine wheels are arranged, wherein the turbine wheels are arranged to each operate one compressor wheel, arranged in an air inlet conduit to the combustion engine, said electronic control device comprising: comprising: one or more computer processors; a non-transitory computer-readable medium; a computer program product comprising computer program code stored on the non-transitory computer-readable medium, said computer program code comprising computer instructions to cause the one or more computer processors to perform the operations of: determining a value for the rotational speed of the respective turbine wheels; and controlling the rotational speed of the respective turbine wheels depending on said determined speed, by impacting the fuel injection into those cylinders, whose exhaust conduit is connected with a respective turbine wheel.

15. A motor vehicle comprising: a combustion engine; a supercharge system with several turbine wheels, each of which is arranged in an exhaust conduit from cylinders in the combustion engine, different from the cylinders in whose exhaust conduits the one or several other turbine wheels are arranged, wherein the turbine wheels are arranged to each operate one compressor wheel, arranged in an air inlet conduit to the combustion engine; means adapted to determine a value of the rotational speed in the respective turbine wheels; and a device adapted to control the rotational speed of the turbine wheels depending on information from said means about speed values determined thereby, wherein the device is adapted to control the speed of the respective turbine wheels by impacting the fuel injection into those cylinders, whose exhaust conduit is connected with a respective turbine wheel.

16. A motor vehicle according to claim 15, wherein it is a wheeled motor vehicle, such as a truck or a bus, or a boat.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Below are descriptions of example embodiments of the invention, with reference to the enclosed drawings, in which:

[0019] FIG. 1 is a schematic view, illustrating a system for control of a supercharge system in a combustion engine according to one embodiment of the invention,

[0020] FIG. 2 is a flow chart showing a method according to one embodiment of the invention, and

[0021] FIG. 3 is a diagram of an electronic control device for the implementation of a method according to the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT ACCORDING TO THE INVENTION

[0022] The invention will be described below as applied in a motor vehicle 1. The invention is not, however, limited to this application. The motor vehicle has a combustion engine 2, with two cylinder groups 3, 4 for every four cylinders 5-12. Air is supplied to the cylinders of the combustion engine via an air inlet conduit 13, which, at the very end of the air inlet is divided into two sections 14, 15. Exhausts are led away from the combustion engine via an exhaust pipe 16, 17, connected to each group of cylinders.

[0023] The vehicle's electronic control device 18 is schematically indicated, and adapted to e.g. control fuel injection into the engine's cylinders, which is indicated by arrows pointing towards schematically displayed injection nozzles 19.

[0024] The combustion engine is equipped with a turbo charger having two turbine wheels 20, 21, which are arranged in each of the exhaust conduits 16, 17 from both cylinder groups 3, 4. The turbine wheels are arranged to operate a compressor wheel 22, 23 each, each arranged in its own section 14, 15 of the air inlet conduit 13, in order to generate a desired charge air pressure supplied to the cylinders of the combustion engine downstream of the compressor wheels 22, 23, via the exhaust conduit section 24.

[0025] Means 25, 26 are arranged to measure the rotational speed of the respective turbine wheels and to send information regarding this to the electronic control device 18. This device 18 is adapted to process such information and subsequently provide a device 27schematically drawnwith a command to control the speed of the respective turbine wheels 20, 21 by impacting the fuel injection into those cylinders, whose exhaust conduit 16, 17 is connected with the relevant turbine wheel. Such impact on the fuel injection may for example occur through variation of the amount of fuel injected, so that, for example, more fuel is injected into cylinders associated with a turbine wheel that has a lower rotational speed, than what is the case for the second turbine wheel, and accordingly the pulse content appearance of the exhaust flow in this exhaust conduit may be altered, so that the rotational speed of the turbine wheel increases. Another possibility is to carry out post-injections of fuel into the cylinders associated with a turbine wheel, in order thus to increase the rotational speed of the turbine wheel. It is also possible to vary the crankshaft angle at which fuel injection occurs in the different cylinders, so that the injection occurs, for example, at an angle of 8 in one cylinder and at 12 in another, in order to impact the appearance of the exhaust pulses from the cylinders. The invention is not limited, however, to these manners of impacting the fuel injection into the cylinders, but covers every possible such impact.

[0026] Since the system may in this manner control the rotational speed of the respective turbine wheels separately from the control of the rotational speed of the second turbine wheel, it may e.g. be ensured that the speed of the turbine wheels is always equally high, if desirable, which means there is a possibility of operating the compressor wheels very close to their pumping limit without any risk of pumping arising. Accordingly, a combination of a high output at high speeds and of a good torque at lower speeds of the compressor wheels is achieved. However, it is also conceivable that, for some reason, the pumping limit is not the same in the various compressor parts, and that a certain distance between the rotational speeds of both compressor wheels is desired. about the desire to compensate for an existing engine deviation may also be a reason to control the turbine wheels, and accordingly the compressor wheels, towards different rotational speeds, or to the same speed if this improves the engine characteristics, and if there is an inbuilt static engine deviation, then it also is not absolutely necessary to measure the rotational speed of the turbines, but the constitution of the injections may be controlled towards expected static differences.

[0027] FIG. 2 shows a flow chart illustrating an embodiment of a method according to the present invention, for the control of a flow of a turbo charger of the type described above. In a first step S.sub.1 the rotational speed of each turbine wheel is measured. Subsequently, in a second step S.sub.2, the measured speeds are compared with each other, following which, in a third step, S.sub.3, the fuel injection into the cylinders is controlled towards the same rotational speed of the turbine wheels. As mentioned above, in a method according to the invention, said control may occur with a number of other objectives than the one mentioned here.

[0028] A computer program code for the implementation of a method according to the invention is suitably included in a computer program, loadable into the internal memory of a computer, such as the internal memory of an electronic control device of a combustion engine. Such a computer program is suitably provided via a computer program product, comprising a data storage medium readable by an electronic control device, which data storage medium has the computer program stored thereon. Said data storage medium is e.g. an optical data storage medium in the form of a CD-ROM, a DVD, etc., a magnetic data storage medium in the form of a hard disk drive, a diskette, a cassette, etc., or a Flash memory or a ROM, PROM, EPROM or EEPROM type memory.

[0029] FIG. 3 very schematically illustrates an electronic control device 18, comprising execution means 30, such as a central processor unit (CPU), for the execution of computer software. The execution means 30 communicates with a memory 31, e.g. a RAM memory, via a data bus 32. The control device 18 also comprises a data storage medium 33, e.g. in the form of a Flash memory or a ROM, PROM, EPROM or EEPROM type memory. The execution means 30 communicates with the data storage means 33 via the data bus 32. A computer program comprising computer program code for the implementation of a method according to the invention is stored on the data storage medium 33.

[0030] The invention is obviously not limited in any way to the embodiments described above, but numerous possible modifications thereof should be obvious to a person skilled in the area, without such person departing from the spirit of the invention as defined by the appended claims.

[0031] The number of turbine wheels and compressor wheels operated by these may be different, i.e. greater, than displayed.