Process for tuning the switching state of a torque converter loc

Details Process for tuning the switching state of a torque converter loc Process for tuning the switching state of a torque converter loc

1998-12-31

2000-06-13

Lorence, Richard M.

192 clutches and power-stop control

Vortex-flow drive and clutch

Including drive-lockup clutch

192103C, 701 67, F16H 6114

Patent

active

060737409

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for tuning the switching state of a converter lock-up clutch (WK), in an automatic transmission, to the output speed of rotation of the output shaft or the speed of rotation of the driving wheels of a vehicle by means of an electronic controller (EGS), with a computer unit, and an electric pressure regulator (EDS).


BACKGROUND OF THE INVENTION

Already known from the practice are motor vehicles having automatic transmission torque converter lock-up clutches which can be operated in an "opened" or "activated" state. The "activated" state comprises of the regulated slipping and closed state.
Such a torque converter lock-up clutch has been described, for example, in ATZ Automobiltechnische Zeitschrift 96 (1994) 11. The most important input variables for the regulator of said known torque converter lock-up clutch are the engine speed of rotation and the turbine speed of rotation. By subtraction of those two input variables, the torque converter slip is computed as the regulating variable. The command variable WK nominal slip is laid down in a performance graph in an electronic transmission controller (EGS).
An electric pressure regulator (EDS) serves the actuator for the pressure control of said torque converter lock-up clutch, which, in turn, is controlled by the electronic transmission controller (EGS) via a current-regulated final step. The EDS converts the preset control current according to its characteristic line to a proportional hydraulic pressure. By said EDS, for example, in a 2-line torque converter with two control valves, both the torque converter pressure, which acts upon the rear side of the torque converter clutch piston, and the torque converter clutch pressure which closes the torque converter clutch piston, are controlled.
The torque converter lock-up clutch is designated as "open" or "opened" when no torque is transmitted via the torque converter lock-up clutch.
In an "activated" state the piston of the torque converter lock-up clutch is loaded with pressure. One or more friction disc(s) are compressed by the resulting piston force and a corresponding transmission torque is produced.
In the so-called "quick opening" of the torque converter lock-up clutch, the torque transmitted by the torque converter lock-up clutch is quickly broken down to low values (for example, <50 Nm) or the torque converter lock-up clutch is completely opened.
Together with the usual control functions, said torque converter lock-up clutch has different special functions in order to optimize the properties.
Thus, in this torque converter lock-up clutch, a process is known in which the torque converter lock-up clutch is always open below a threshold temperature, and in which during the warm up the nominal slip is raised in comparison with the normal operation.
By another control process, the operation of the torque converter lock-up clutch is eliminated during very elevated transmission temperatures in order to protect the friction areas against overheating.
In addition, a process for quick filling is known where the piston of the torque converter lock-up clutch, in the transition from open to regulated state, is moved to the regulating position.
By another switching process, the operation of the torque converter lock-up clutch is maintained even during a gearshift in order to prevent a high rotation of the engine wherein the nominal slip is raised during a gearshift.
However, certain driving situations are not correctly detected by the known torque converter lock-up clutch and the electronic transmission controller thereof, resulting in the known torque converter lock-up clutch remaining, for example, "activated" even though it should have been opened.
Such a driving situation is the spinning of the driving wheels of a vehicle on a smooth ground, while the torque converter lock-up clutch is activated, and the subsequent transition to a ground of high frictional value. When the driving wheels spin, in the known torque converter lock-up clutches, a switch is made to a next higher g

REFERENCES:
patent: 4691812 (1987-09-01), Takazawa
patent: 4730709 (1988-03-01), Kawata et al.
patent: 5277287 (1994-01-01), Ishii et al.
patent: 5325946 (1994-07-01), Kashiwabara et al.
patent: 5480363 (1996-01-01), Matsubara et al.
patent: 5816979 (1998-10-01), Shiiba et al.
patent: 5935043 (1999-08-01), Watanabe et al.
ATZ Automobiltechnische Zeitschrift 96 (1994) 11, by Ferit Ku.cedilla.ukay and Christian Bock, pp. 690-697.

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