Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1999-06-07
2001-07-17
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S065000, C701S071000, C701S074000, C701S082000, C477S176000, C477S904000
Reexamination Certificate
active
06263273
ABSTRACT:
The invention relates to a process for controlling an automatic transmission in a vehicle in which an electronic transmission control sets a drive state of low friction value when slip is detected in the input gears.
BACKGROUND OF THE INVENTION
In automatic transmissions, a driver can activate the corresponding program via an E/S/W (economy/sport/winter) w push-button. In automatic transmissions, having a so-called “intelligent switching program”, the selection of the switching point or the step of the winter program is automatic. A process for activating the winter program has been disclosed, e.g., in ATZ Automobiltechnische Zeitschrift 94 (1992), page 432. It is proposed that unauthorized slip be detected from the comparison of driven and non-driven gears. Depending on the result of said examination, a slip index is set. The winter program is activated when within a fixed preset time period, the sum of these values exceeds a preset limit value. In the practice of the process described, there can arise the problem of reaction time lapses. Reaction time lapses are a result of fixed slip index values, which create long periods between the occurrence of the slip and the activation of the winter program.
In view of the above, the problem to be solved by the invention is for the invention to quickly adapt the performance characteristics of the automatic transmission to the outerwinter operation driving conditions. The invention solves the problem by the fact that a driving state is set at a low friction value when either an ABS deceleration or a slip is detected.
If an ABS deceleration state signal is received by the ABS control unit of the electronic transmission control, a meter determines, via an ABS evaluation function, the actual acceleration of the vehicle or a parameter corresponding to an actual acceleration (e.g., gear speed increase). The ABS evaluation function is carried out so that with each value of the actual acceleration of the vehicle, a meter offset will be coordinated via a characteristic line. The meter count results from the actual meter count plus the offset. If the meter count exceeds a limit value, an electronic transmission control activates the winter operation.
In the case of a slip, the meter will make its determination by means of a slip evaluation function from the theoretical/actual comparison of the vehicle acceleration or a parameter corresponding to the theoretical/actual comparison of the vehicle acceleration (e.g. torque reserve). The slip evaluation function is carried out so that with each value of the theoretical/actual comparison of the vehicle acceleration, a meter offset is coordinated via a characteristic line. If the meter count exceeds a limit value, an electronic transmission control activates the winter operation.
SUMMARY OF THE INVENTION
Wherefore, it is an object of the present invention to overcome the aforementioned problems and drawbacks associated with the prior art designs of the process of controlling automatic transmissions.
A further object of the invention is to make a transmission switch quicker to the winter operation mode when there is great divergence between driver's wish (theoretical acceleration) and actual driving behavior (actual acceleration), the latter which results in a high meter offset.
Yet another object of the invention is the activation of the winter operation mode to actively assist in a low friction value ABS deceleration on a subsoil. It is known that in an ABS deceleration, the wheel revolutions cannot be used as sensor signals since they are clocked and because between vehicle wheel and underground, a slip can occur up to 30% before the ABS control unit reopens the wheel brake.
A further object of the invention is the activation of the winter operation mode as activated by the driver via the program selector button.
Yet still another object of the invention is the winter operation mode being activated by one to several drive programs which are dialed according to the inclination of the road (slopes, ascents) thereby allowing the transmission to upshift earlier when driving uphill than when driving downhill. The inclination of the road can be determined, e.g., by any one of the already known processes. The winter operation is therefore activated not only in the case of a detection of a low road friction value. It can also be activated by the signal of an anti-slip control system.
Yet a still further object of the invention consists in the transmission remaining in winter operation mode when the vehicle has been decelerated to a stop thereby allowing the vehicle to start up again in winter operation mode. When the drive state is reset to low friction value and active winter operation mode, the meter count is cyclically decremented. The decrement takes place only above a presettable vehicle speed threshold or one of the parameters corresponding to the vehicle speed (e.g. transmission output speed), such as 10 km/h.
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Welter, Andreas, u.a. “Die Adaptive Getriebesteuerung für BMW-Automobile”. InATZ—Automobiltechnische Zeitschrift 95, 1993, 9, S.420-434.
ATZ Automobiltechnische Zeitschrift 94 (1992) “Die Adaptive Getriebesteuerung für die Automatikgetriebe der BMW Fahrzeuge mit Zwölfzylindermotor”, by Andreas Welter, Rudolf Kragl, Harald Ender and Harry Martin, pp. 428-438.
Henneken Markus
Herbster Kai-Uwe
Jauch Friedemann
Mauz Thomas
Schuler Franz-Josef
Davis & Bujold P.L.L.C.
Louis-Jacques Jacques H.
ZF Friedrichshafen AG
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