Internal-combustion engines – Starting device – Condition responsive control of starting device
Reexamination Certificate
2000-04-28
2001-06-26
Dolinar, Andrew M. (Department: 3748)
Internal-combustion engines
Starting device
Condition responsive control of starting device
C123S179220, C290S031000, C290S03800C
Reexamination Certificate
active
06250270
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a starting/driving unit for an internal combustion engine of a motor vehicle, having at least two starting methods, having a clutch between the crankshaft, the engine, and the vehicle transmission, and also having an electric machine which is connected directly to the engine and/or the clutch is connected to the engine.
A starting/driving unit of this kind for two starting methods has been disclosed by DE 197 05 610 A1. In this connection, the starting method is chosen as a function of the temperature of the engine. The starting methods require two starting systems. The electric machine that serves as a motor and generator is used to start the warm engine while a conventional starter, together with electric machine, is used for starting when the engine is cold. The two starting systems require a high expenditure in order to also be able to function in stop-and-start operation and in inertial system operation.
Conventional starters have disadvantages for a number of reasons. In terms of the service life of the starter motor, in terms of the service life of the pinion and the toothed ring as well as the override clutch, and in terms of noise generation, starters of this kind do not attain the goal if the number of starting cycles is increased due to repeated starts when the engine is warm, e.g. in stop-and-start operation at traffic signals, in traffic jams, or after a thrust phase, in which a faster and quieter start is required. Even if the starter is provided with improved electronics, which results in an increased starting cycle count, this is not sufficient to achieve required starting cycle counts of >200,000. The starting system that is improved in this manner cannot achieve the desired starting time and quietness.
In addition, WO 98/05882 has already disclosed providing a starting generator for direct starting. This embodiment cannot be realized with a conventional 12 V to 24 V lead starter battery because of the starting energy and the starting output during a cold start. Furthermore, the electric motor would have to be enlarged by more than a factor of 3 in relation to the demand for the generator output, which among other things, can also lead to difficulties with the structural size. However, extremely high starting moments and battery outputs are not required in order to start the warm engine.
The use of a starting generator for an impulse start according to DE 197 45 995 A1, in which a starting generator is connected to the crankshaft by way of a start coupling between the crankshaft and a flywheel in addition to or in lieu of the usual coupling between the flywheel and the vehicle transmission, functions so that when the engine (and transmission) are uncoupled, the electric motor first accelerates the flywheel mass to the drive speed (e.g. 1000 rpm) and then with a rapidly following start coupling or clutching, drives the engine via the rotation energy. This impulse start is suitable for normal cold starts, but due to time constraints, is unfavorable for re-starting when the engine is warm both at traffic signals and after the end of thrust phases.
SUMMARY OF THE INVENTION
The object of the invention is to produce a starting/driving unit of the type mentioned at the beginning, which is suitable for high starting cycle counts by itself with an electric machine and without a conventional starter, functions quietly, and remains within energy demand limits.
This object is attained according to the invention by virtue of the fact that each starting method is preceded by a start clearing phase in which when the clutch between the crankshaft, the engine, and the vehicle transmission is engaged, and has an electric machine which is connected to the engine by way of the clutch.
During the start clearing phase, when the clutch is engaged, the current starting conditions are detected, the subsequent operating phases are selected based on the current starting conditions, and the starting parameters for them are selected. Preferably a starting generator is used as the electric machine.
A simple detection of the current starting conditions is achieved by virtue of the fact that in the start clearing phase, the starting control unit uses a speed sensor to detect the speed progression of the crankshaft and utilizes this speed progression to derive the starting method and the starting parameters. The drag moment that is present during starting has an effect on the speed progression. When the drag moment is high, the engine is cold, when it is low, the engine is already warm. Alternatively, the starting method can be determined by way of a temperature measurement or a plausibility control can be executed with it. As a rule, the speed progression has already been detected by means of a crankshaft speed sensor so that this can also be used for the derivation of the existing starting conditions. The correct starting method is identified through preset limit values of the measured drag moment.
According to one embodiment, considerable differences arise in the speed progression by virtue of the fact that the decision as to the starting method can be derived from the region of the speed progression between the first and/or second maximum and/or the first and/or second minimum of the speed. As a result, definite conclusions can be drawn about the existing drag moment and can be used to select the correct starting method.
With a high drag moment, the impulse start is selected as the operating phase. With an even higher drag moment, which is too high for the normal impulse start, before the impulse starting phase, a so-called dry impulse starting phase, i.e. without ignition and injection, is initiated in which the synchronization and a possible preinjection of fuel are executed by means of an electronic motor control unit (Motronic). This is an advance impulse start in which when the clutch is disengaged, the starting generator first accelerates the flywheel to the necessary speed in order to then produce a position detection/synchronization when the clutch is engaged.
The electric machine can be designed with or without a reduction gear and can be directly connected to the transmission shaft and can be connected to the engine by means of a rapidly engaging clutch.
REFERENCES:
patent: 4626696 (1986-12-01), Maucher et al.
patent: 6032632 (2000-03-01), Bolenz et al.
patent: 6098584 (2000-08-01), Ahner et al.
Ackermann Manfred
Ahner Peter
Dolinar Andrew M.
Robert & Bosch GmbH
Striker Michael J.
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