Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Patent
1998-05-11
2000-08-15
Louis-Jacques, Jacques H.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
701 54, 701 55, 701 56, 477110, 477121, 477156, G06F 700
Patent
active
061049743
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION.
The present invention relates to a system for changing the gear ratio in a multi-step reduction gear, of the definition of the species of claim 1.
BACKGROUND INFORMATION
It is known from the related art, as represented by European Patent No. 0 001,298 (corresponding to U.S. Pat. No. 4,228,700), that when changing gears with an automatic multi-step reduction gear, the respective gear shift valves can be driven as a function of whether the engine is in pushing (coasting) or pulling (traction) operation. By linking a pushing or pulling operation detected with the type of gear shifting (upshifting or downshifting), a gear shifting strategy can be selected to permit the most comfortable and gear-protective adjustment of engine speed to the new gear. In particular, the intent is for the shifting of the required gear shift valves at the start of the shifting operation to take place with a positive overlap, namely at the start of the shifting sequence in power upshifting and in pushing downshifting and at the end of the shifting sequence in pushing upshifting and power downshifting.
German Patent Application No. 42 32 974 (corresponds to British Patent No. 2,271,198) and German Patent Application No. 42 39 711 discribe a model for calculating the indexed engine torque as a function of engine speed, engine load, firing angle, ignition blanking stages and of loss torque as a function of engine speed, engine load, engine temperature and consumers (e.g., a.c. compressor). In German Patent Application No. 44 07 475, this engine torque model for calculating the indexed engine torque is supplemented by the lambda function, i.e., the dependence on the fuel-air ratio. These publications disclose the precise calculation of instantaneous engine output torque at each operating point.
SUMMARY OF THE INVENTION
An object of the present invention is to provide for a simple and accurate selection of gear shifting strategies in changing gear in multi-step reduction gears.
The present invention is based on a system for changing the gear ratio in a multi-step reduction gear, where a flywheel is accelerated or decelerated during a change in gear ratio. The flywheel, consisting essentially of engine components and the converter, must be accelerated in downshifting operations, for example, whereas the flywheel is decelerated in upshifting operations. To change the gear ratio, at least two different selectable strategies are provided.
An important feature of the present invention is that a first value representing the engine output torque and a second value representing the torque demand for accelerating or decelerating the flywheel are detected first. To change the gear ratio, one of the strategies mentioned above is then selected on the basis of a comparison of the first value detected with the second value detected.
As mentioned above, methods are known from the related art for selecting different shifting strategies for changing the gear ratio according to whether pushing or pulling operation of the motor vehicle is detected. This detection of pushing or pulling depends on the instantaneous throttle valve angle detected. However, this method is inaccurate and application is relatively complicated. The present invention offers the advantage that it permits very accurate recognition of whether the gear shifting to be initiated is a pushing or pulling shifting. In addition, the system according to the present invention can be applied relatively easily. Other functions of engine control, e.g., heating of the catalyst, have no effect on pushing or pulling detection according to the present invention.
An advantageous exemplary embodiment of the present invention provides for detecting as the type of change in gear ratio change whether there is a change to a higher gear (upshifting) or to a lower gear (downshifting) and whether the strategies are selected as a function of this detected type change. The aim of the exemplary embodiment is that in addition to the torque comparison according to this invention, the
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patent: 4228700 (1980-10-01), Espenschied et al.
patent: 5325740 (1994-07-01), Zhang et al.
patent: 5407401 (1995-04-01), Bullmer et al.
patent: 5603672 (1997-02-01), Zhang
Denz Helmut
Zhang Hong
Louis-Jacques Jacques H.
Robert & Bosch GmbH
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