Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1997-04-18
1999-06-15
Marmor, Charles A.
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
477148, 477149, F16H 6106
Patent
active
059116480
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a process for controlling and regulating an automatic transmission.
BACKGROUND OF THE INVENTION
EP-OS 0435 374 has disclosed a process for controlling an automatic transmission where the gearshift from a first to a second reduction ratio is effected by a first clutch disengaging and a second clutch engaging. With the beginning of the gearshift, the pressure of the first clutch is lowered whereby the clutch is not allowed to slip. The curve of a turbine speed establishes the disengagement point of the first clutch. After the disengagement point is established, the slip of the second clutch is controlled in accordance with a time function.
A process for automatic control of an automatic transmission has also been described in the not pre-published German patent application P 44 24 456.8 of Jul. 12, 1994. The process consists of the following steps for an upshift: rapid-filling phase, filling-equalizing phase, load take-up phase, gradient-setting phase, sliding phase, gradient-breakdown phase and closing phase. A disadvantage of the aforementioned process is that a defective filling of the clutch to be engaged due to temperature, for example, is not taken into account.
SUMMARY OF THE INVENTION
The problem to be solved by the invention is thus to detect a defective meshing of the engaging clutch and to ensure a reliable gearshift sequence.
According to the invention, the problem is solved by means of a process for controlling and regulating an automatic transmission actuated by a drive unit, preferably an internal combustion engine. On the basis of input variables, an electronic control unit controls, via electromagnetic actuators, clutches and brakes of the automatic transmission. A change over of the automatic transmission from a first to a second reduction ratio is carried out by a sequence controlled disengagement of a first clutch and engagement a second clutch, with no excessive increase of the transmission input speed occurring during this change over. A defective meshing of the second clutch is detected when, during a load take-up phase, the transmission input speed becomes higher than the product of a transmission output speed multiplied by the first reduction ratio or the transmission input speed becomes higher than a first limiting value dn1. Upon detection of a defect, the sequence control is discontinued and a regulating phase is started for the disengaging clutch.
The solution according to the invention offers the advantage of a change from the control process to the regulation process for the first clutch occurring only in particular cases. In comparison with an exclusively regulating process, a substantial reduction of coordination parameters thus results. A further advantage exists in the elimination of the difficulty in the regulating passage of the first clutch from adhering to sliding.
In an embodiment according to the invention, it is proposed that in the regulation phase the pressure level of the first clutch is adjusted so that the transmission input speed does not exceed a second limiting value dn2.
In another embodiment according to the invention, it is proposed that the regulation phase of the clutch terminate when the difference of the transmission input speed minus the product of the transmission output speed multiplied by the first reduction ratio falls below a third positive limiting value dn3. Accordingly, a passage from a first pressure level, at the end of the regulation phase, to a second pressure level is sloped. The second pressure level corresponds to the pressure level calculated from the sequence control.
BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment is shown in the drawings in which:
FIG. 1 is a phase diagram; and
FIG. 2 is a time diagram of an upshift.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
FIG. 1 shows a phase diagram for the sequence control consisting of: rapid-filling phase 1, filling-equalizing phase 2, load take-up phase 3, gradient-setting phase 4, sliding phase 5, gradient-breakdown phase 6, load take-up phase 7 and closi
REFERENCES:
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patent: 4793216 (1988-12-01), Hiramatsu et al.
patent: 5113343 (1992-05-01), Hunter et al.
patent: 5401219 (1995-03-01), Kimura et al.
patent: 5443427 (1995-08-01), Ataka et al.
patent: 5704874 (1998-01-01), Shimada et al.
patent: 5722913 (1998-03-01), Gierer
Dreibholz Ralf
Frotscher Gerd
Schober Thomas
Vohmann Martin
Lund Scott
Marmor Charles A.
ZF Friedrichshafen AG
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