Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1994-11-14
1996-11-05
Friedman, Carl D.
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
477149, F16H 6126
Patent
active
055710603
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for correcting the shifting quality of an automatic transmission which is coupled to an engine and in which the friction elements are brought into engagement via correcting elements acting on the pressure or oil throughput to carry out shifting processes where the line pressure acted on by the correcting element is registered and corrected as a function of various operating parameters.
The term "shifting quality" refers to the shifting behavior of the clutches or idlers of an automatic transmission from one gear to the next. In such cases it may occur that the clutches transmit the shifting process too "hard" or too "soft" since it is known that the rotation speeds of the driven and driving shafts must be equalized.
These shifting quality differences may stem from deviations of the transmission components in the series such as, for example
Therefore a correction is necessary to capture these deviations.
From German OS 41 20 761 a line pressure control for an automatic transmission is known in which a deterioration in shifting properties caused by friction elements, wear, or by a change in hydraulic fluid temperature is prevented by comparing the shifting time duration with a preassigned optimal time duration. If a deviation is registered the line pressure is raised or lowered accordingly. In the case when additional devices are used such as compressors for air conditioners, the actually registered shifting parameters are falsified which can lead to the slipping of the friction elements on the one hand or to jerky shifting of the transmission on the other.
The comparison of the present shifting time duration with a preassigned optimal time duration does not cover all of the dynamic processes which may occur during a shifting process.
EP-A-0 176 750 describes a process for the electronic control of an automatic vehicle transmission in which electrohydraulically activated friction elements cause the shifting processes. The shifting takes place through an adaptive control using hydraulic pressure as a control magnitude. The objective is to avoid shifting quality fluctuations. In the above noted procedure it is provided that nominal values are compared with real values to form correction values, and these are used for correcting the control magnitude. As control magnitudes one can also use the time duration of the shifting process. Ultimately the actually relevant magnitude, the translation ratio, is always only indirectly influenced. The shifting pressure or the shifting time permit no direct conclusions regarding the real translation ratio.
The present invention has the objective of devising a process for correcting shifting quality which refers to an optimal criterion representing the shifting quality.
This problem is solved according to the invention by forming for each specific gear change, besides the translation ratio found as a function of time from the initiation of the shifting process until its completion, also the first derivative, and in the electronic device assigning values of the translation ratio to the corresponding values of the first derivative in the form of a characteristic line, and comparing these measured characteristic lines with reference characteristic lines present in the device including a tolerance range, and in the case of inequality determining a correction factor which, upon the next identical gear change, leads to an incremental increase or decremental decrease of a correction value by the correction factor and thus a correction of the line pressure or the oil flow is performed by correcting elements acting on the pressure or oil throughput modulated by the electronic device in accordance with the correction value.
According to an especially advantageous version of the invention it is provided that the device will output a correction value which is preferably larger than 3 through a display or an acoustic warning device and by indication of an improperly occurring shifting process. It is also envisioned that the line pressure or oil throughpu
REFERENCES:
patent: 4742461 (1988-05-01), Eschrich et al.
patent: 4970916 (1990-11-01), Narita
patent: 5086670 (1992-02-01), Nitz et al.
patent: 5111718 (1992-05-01), Iizuka
Becker Gernot
Kleila Hans
Reitenbach Rainer
Adam Opel AG
Conkey Howard N.
Friedman Carl D.
Smith Creighton
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