Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1997-01-10
1998-08-18
Ta, Khoi Q.
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
477149, 477156, F16H 6106
Patent
active
057952655
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for controlling an automatic transmission.
BACKGROUND OF THE INVENTION
EP-OS O 435 374 has disclosed a process for controlling an automatic transmission wherein a change from a first to a second reduction ratio results by a first clutch disengaging and a second clutch engaging. With the beginning of the change the pressure of the first clutch is lowered, so that it does not slip. The curve of a turbine speed establishes the disengagement point of the first clutch. After reaching the disengagement point, the clutch slip of the second clutch is controlled in dependence on a time function. It cannot be understood, from the OS, how a load take over of the second clutch from the first clutch is carried out.
An automatic transmission in group design is known from EP-OS O 565 111. Both transmission parts contain planetary gear sets and free wheels. Within the gear sequence the first and second parts are engaged only once during an upshift from the second to the third gear. Here the shifting devices in the two transmission parts work in opposition, that is, in the first part an upshift is carried out and in the second part a downshift is carried out. It is disadvantageous that a group shifting of both transmission parts is carried out only during an upshift.
SUMMARY OF THE INVENTION
The problem to be solved by this invention is to provide a process for controlling an automatic transmission, which can be applied in particular, to a group transmission.
According to the invention, the problem is solved by the fact that in a first gearshift method the shifting operation consists of the phases rapid filling, filling equalization, load take-over, gradient setting, sliding, gradient breakdown and closure. In a second gearshift method, the shifting operation consists of the phases rapid filling, filling equalization, gradient setting, sliding, gradient breakdown, load take-over and closure. A first gearshift method according to the invention is to be understood as an upshift in pull load or a downshift in push load. The second gearshift method, according to the invention, is to be understood as a downshift in pull load or an upshift in push load.
The solution, according to the invention, offers the advantage that the process in question is a dynamic process. Dynamic means that during the shifting the selection and transition from the first to the second clutch result automatically and continuously whereby a steady curve of the output torque is obtained under all conditions of travel. In a desired performance, the driven presets an internal combustion engine via an accelerator pedal which enters immediately in the gearshift calculation or in determining the gearshift method. If the gearshift transition begins, for example, as downshift in pull load, then immediately after the driver has released the accelerator pedal the gearshift method is changed so as to terminate the gearshift as downshift in push load.
In one embodiment it is proposed that in the first gearshift method, during the rapid filling phase, the second clutch is loaded with high pressure and the pressure of the first clutch is lowered from a first to a second level, the second level being above the slip limit of the first clutch; in the filling equalization phase the second clutch is filled-to a lower pressure level pF and the pressure of the first clutch remains at the second level; in the load take-over phase the pressure of the second clutch is raised to a final value pE1=f (parameter 1) and the pressure of the first clutch is lowered from the second level to zero; in the gradient setting phase the pressure of the second clutch is raised from the final value pE1 to a final value pE2=f (parameter 2); in the sliding phase the pressure of the second clutch is linearly raised or a presynchronization point is detected therein; in the gradient breakdown phase the pressure of the second clutch is reduced to a final value pE3=f (parameter 3); the closure phase begins when the final value pE3 is reached.
In another embodime
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Domian Hans-Jorg
Dreibholz Ralf
Frotscher Gerd
Schober Thomas
Kwon Peter T.
Ta Khoi Q.
ZF Friedrichshafen AG
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