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1. (WO2007001230) A METHOD AND AN APPARATUS FOR CONTROLLING AN ENGINE
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Claims
1. 1. A method for controlling the output torque of an engine (13) in a drive train of a motor vehicle, said drive train comprising a transmission (9) coupled to the engine and having a plurality of engageable gear ratios, in which the engine output torque is limited to not exceed a maximum engine output torque while considering torques resulting therefrom upon components of said drive train, characterized in that
a maximum limit transmission output torque calculated from the so called slip torque of the vehicle, i.e. the maximum torque applicable to the wheels of the vehicle before they start to slip on a certain ground resulting in a maximum friction coefficient, for a certain tyre dimension, for a maximum axle or bogie load pressure and for the highest transmission ratio of said
transmission, is used for controlling the engine to delimit the engine output torque to a value resulting in a transmission output torque below said maximum limit transmission output torque.
2. A method according to claim 1 , characterized in that it comprises the steps of:

- checking whether information about the gear ratio presently engaged is available, and
- using the result of said checking for determining the maximum engine output torque which is allowed to result from the control of the engine.
3. A method according to claim 2, characterized in that in the case that said information resulting from said checking indicates that there is a gear ratio presently engaged making it impossible to obtain a transmission output torque exceeding said maximum limit transmission output torque no limitation is set to the engine output torque when controlling the engine.
4. A method according to claim 2 or 3, characterized in that in case said checking results in a knowledge of the gear ratio presently engaged for all possible gear ratios of the transmission the engine is controlled according to an individual limit of the engine output torque set for each gear ratio.
5. A method according to claim 2 or 3, characterized in that in case the information resulting from said checking does not contain any exact indication of the gear ratio presently engaged the engine is controlled according to the highest possible transmission ratio determined out of the information available with the limit for the engine output torque set by this transmission ratio, so that said maximum limit transmission output torque will not be exceeded.
6. A method according to claim 5, characterized in that in case said checking results in information revealing that the gear ratio presently engaged belongs to a certain group of gear ratios said highest possible transmission ratio is determined to be the highest transmission ratio of the gear ratios belonging to said group.
7. A method according to claim 6, characterized in that in case said checking results in information stating that a gear ratio belonging to a group of gear ratios with a low transmission ratio comparing to other groups of gear ratios of said transmission and having a highest possible transmission ratio below a predetermined transmission ratio is presently engaged the engine is controlled without setting any limit to the engine output torque.
8. A method according to any of the preceding claims, characterized in that it is carried out for a vehicle having a transmission (9) with a possibility to select a high range or a low range of gear ratios.
9. A method according to claims 7 and 8, characterized in that when said checking results in information stating that a gear ratio presently engaged belong to said high range the engine is controlled without setting any limit to the engine output torque.
10. A method according to claim 5, characterized in that it is carried out for a vehicle having a transmission including a so-called split position selector (4) enabling selection of at least two different gear ratios for a gear engaged, said two different gear ratios being with respect to the transmission ratio located between the transmission ratios of the two gears next to the gear in question, and that information about the position of said split position selector is considered when determining said highest possible transmission ratio for determining the upper limit for the engine output torque when controlling the engine.
11. A method according to claim 5, characterized in that it comprises the step of measuring the speed of the vehicle, and that the speed measured is compared with a speed limit value and if the speed value measured is above this speed limit value the engine is controlled without any limitation set to the engine output torque.
12. An apparatus for controlling the output torque of an engine (13) in a drive train of a motor vehicle, said drive train comprising a transmission (9) coupled to the engine and having a plurality of engeagable gear ratios, said apparatus comprising a control unit (16) for controlling the fuelling of said engine and a device (17) adapted to determine a maximum engine output torque not to be exceeded through the control of the control unit while considering torques resulting from such a control upon components of said drive train, characterized in that said device (17) is adapted to calculate a maximum limit transmission output torque from the so-called slip torque of the vehicle, i.e. the maximum torque applicable to the wheels of the vehicle before they start to slip on a certain ground resulting in a maximum friction coefficient, for a certain tyre dimension, for a maximum axle or bogie load pressure and for the highest transmission ratio of said transmission, and that the control unit (16) is adapted to control the fuelling of the engine so as to delimit the engine output torque to a value resulting in a transmission output torque below said maximum limit transmission output torque.
13. An apparatus according to claim 12, characterized in that it comprises means (12) adapted to check whether information about the gear ratio presently engaged is available, and that said device (17) is adapted to use the result of said checking for determining the maximum engine output torque which is allowed to result from the control of the engine (13).
14. An apparatus according to claim 13, characterized in that said device (17) is adapted to determine that the control unit (16) shall control said fuelling of the engine without any limitation in case that the checking indicates that there is a gear ratio presently engaged making it impossible to obtain a transmission output torque exceeding said maximum limit transmission output torque.
15. An apparatus according to claim 13 or 14, characterized in that said control unit (16) is adapted to control the fuelling of the engine according to an individual limit of the engine (13) output torque set for each gear ratio in case said checking results in a knowledge of the gear ratio presently engaged for all possible gear ratios of the transmission.

16. An apparatus according to claim 13 or 14, characterized in that the control unit (16) is adapted to control the fuelling of the engine (13) according to the highest possible transmission ratio determined out of the information available with the limit for the engine output torque set by this transmission ratio in case said checking results in information not containing any exact indication of the gear ratio presently engaged, so that said maximum limit transmission output torque will not be exceeded.
17. An apparatus according to claim 16, characterized in that said device (17) is adapted to determine said highest possible transmission ratio to be the highest transmission ratio of the gear ratios belonging to a group of gear ratios in case a checking results in information revealing that the gear ratio presently engaged belongs to a certain group of gear ratios and the control unit (16) is adapted to control the fuelling of the engine (13) according to that.
18. An apparatus according to claim 17, characterized in that the control unit (16) is adapted to control the fuelling of the engine (13) without setting any limit to the engine output torque in case said checking results in information stating that a gear ratio belonging to a group of gear ratios with a low transmission ratio comparing to other groups of gear ratios of said transmission and having the highest possible transmission ratio below a predetermined transmission ratio is presently engaged.
19. An apparatus according to any of claims 12-18, characterized in that it is adapted to be arranged in a vehicle having a transmission (9) with a possibility to select a high range or a low range of gear ratios.
20. An apparatus according to claim 19, characterized in that said control unit (16) is adapted to control the fuelling of the engine (13) without setting any limit to the engine output torque when said checking results in information stating that a gear ratio presently engaged belongs to said high range.
21. An apparatus according to claim 16, characterized in that it is adapted to be arranged in a vehicle having a transmission (9) including a so-called split position selector (4) enabling selection of at least two different gear ratios for a gear engaged, said two different gear ratios being with respect to the transmission ratio located between the transmission ratios of the two gears next to the gear in question, and that said device (17 ) is adapted to consider information about the position of said split position selector when determining said highest possible transmission ratio for determining the upper limit for the engine output torque resulting from the control of the fuelling of the engine (13) by said control unit (16).
22. An apparatus according to claim 16, characterized in that it comprises measuring means (20) for measuring the speed of the vehicle, and that said device (17) comprises means adapted to compare the speed measured with a speed limit value and if the speed value measured is above this speed limit value make the control unit (16) to control the fuelling of the engine (13) without any limitation set to the engine output torque.
23. Use of an apparatus according to any of claims 12-22 for controlling the output torque of an engine in a motor vehicle, for example in a bus or lorry.
24. A computer program directly loadable into the internal memory of a computer, which comprises software code portions for controlling the steps of the method according to any one of claims 1-11 when said program is run on the computer.
25. A computer readable medium having a program recorded thereon adapted to make a computer control the steps of the method according to any one of claims 1-11.