DRIVE TRAIN OF A MOBILE VEHICLE

Abstract

A drive-train has an internal combustion engine (1) with an exhaust gas turbocharger, which drives a vehicle wheel (3) by way of a power-branching transmission (2). When there is an increase of the power demanded from the combustion engine (1) but the exhaust gas turbocharger is not yet producing the required charging pressure, an additional motor (4) is always switched into the drive-train in order to deliver torque to the drive-train.

Claims

1-12. (canceled)

13. A drive-train for a mobile vehicle, in which an internal combustion engine (1) drives at least one vehicle wheel (3) by way of a transmission (2), and an additional motor (4) whose power can be switched on in a power path from the combustion engine (1) to the vehicle wheel (3), the power of the additional motor (4) being switchable on for a purpose of delivering power into the power path from the internal combustion engine (1) to the vehicle wheel (3), when a rotational speed specification at the combustion engine (1) exceeds an actual rotational speed of the combustion engine (1), an amount of time for which the additional motor (4) is switched on depends on one of: an exhaust gas emission; a difference between the actual rotational speed of the combustion engine (1) and a specified rotational speed of the combustion engine (1); and a variation of torque of the combustion engine (1).

14. The drive-train according to claim 13, wherein the transmission (2) is a power-branching transmission with a mechanical power branch and a continuously variable power branch.

15. The drive-train according to claim 13, wherein the additional motor (4) is a hydraulic motor that is operable as a pump.

16. The drive-train according to claim 13, wherein the additional motor (4) is an electric motor which is operatable as a generator.

17. The drive-train according to claim 13, wherein the additional motor (4) is connected, either directly or by way of a transmission gear ratio (5), to a drive output shaft of the internal combustion engine (1), and the transmission gear ratio (5) is designed such that a rotational speed of the additional motor (4) is higher than the actual rotational speed of the combustion engine (1).

18. The drive-train according to claim 13, wherein the additional motor (4) is a hydraulic motor which is operable in either an open hydraulic circuit with a high-pressure reservoir, or in a closed hydraulic circuit with a high-pressure reservoir and a low-pressure reservoir.

19. The drive-train according to claim 13, wherein the drive-train is utilized in a wheel loader.

20. A method of switching on an additional motor (4) for delivering power to a drive-train containing an internal combustion engine (1) that drives at least one vehicle wheel (3), the method comprising: detecting a rotational speed specification for the internal combustion engine (1), detecting an actual rotational speed of the internal combustion engine (1), switching on the additional motor (4) for delivering power from the additional motor (4) as a function of a difference between the actual rotational speed and a specified rotational speed of the internal combustion engine (1), and a time for which the additional motor (4) is switched on corresponds to a time at which the combustion engine reaches 90% of its static torque.

21. The method of switching on an additional motor (4) according to claim 20, further comprising, during a braking phase before a clutch reversing phase, obtaining energy for operating the additional motor (4) by operating the additional motor (4) as either a pump or a generator.

22. The method of switching on an additional motor (4) according to claim 20, further comprising, during operation of the combustion engine (1) close to its optimum point, when at that operating point the combustion engine (1) has torque reserves, obtaining energy for operating the additional motor (4) by operating the additional motor (4) as either a pump or a generator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Below, the invention will be explained in further detail with reference to a drawing. The sole FIGURE diagrammatically shows an embodiment of the drive-train according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The single FIGURE shows an internal combustion engine 1 which drives a vehicle wheel 3 by way of a power-branching transmission 2. An additional motor 4, designed as a hydraulic motor with an adjustable stroke volume, is functionally connected with the combustion engine 1 by way of a step-down gearset 5. The step-down gearset 5 is designed such that the rotational speed of the additional motor 4 is higher than the rotational speed of the combustion engine 1. The power-branching transmission 2 is built like the transmission defined in DE 102009001602A1.

[0023] If an increase of the power demand at the internal combustion engine 1 is detected, which can result for example from a change of the accelerator pedal position or a demand from the working hydraulic system, then the additional motor 4 is switched on in a manner that depends on the change of the power delivered by the combustion engine 1. If the power delivered, in particular the torque of the combustion engine 1 changes only slowly but the power demand on the combustion engine 1 shows a large difference, then the additional motor is switched on in such manner that it delivers a high torque.

INDEXES

[0024] 1 Internal combustion engine [0025] 2 Power-branching transmission [0026] 3 Vehicle wheel [0027] 4 Additional motor [0028] 5 Step-down gearset