Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Patent
1998-01-16
1999-11-23
Cuchlinski, Jr., William A.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
701 51, 701 52, 701 63, 477 74, 477 75, 477 92, 477129, 192 351, 192 4R, G06F 1700
Patent
active
059916796
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a safety system for an automatic gearbox in which for an upshift or a downshift an error of the releasing clutch or brake can be detected when the difference of the transmission input speed and the product of the transmission output speed multiplied by the first reduction ratio does not steadily increase.
BACKGROUND OF THE INVENTION
By the generic expression automatic gearbox is to be understood electrohydraulically controlled automatic gearboxs where the gearshift is carried out as cross-over gearshift. In cross-over gearshifts, the gearshift results by a first clutch or brake releasing and second clutch or brake engaging. In automatic gearboxs, it is usual, in general, to monitor the orderly operation thereof in order to prevent situations critical to safety. Monitored are the input signals made available by the sensors, the electromagnetic actuators, the electronic transmission control and, via acknowledged variables, the clutches and brakes that take part in the gearshift. It is of special interest here to detect a faulty releasing of a clutch or brake since this can result in the blocking of the transmission and subsequent destruction. A faulty release is thus extremely critical to safety.
SUMMARY OF THE INVENTION
Therefore, the invention intends to solve the problem of providing, for an automatic gearbox, a safety system which detects a faulty release of a clutch or brake.
According to the invention, the solution of the problem is that at the start of a gearshift, the electronic control device cyclically calculates from the measured transmission output speed, as a first parameter G1, the product of transmission output speed multiplied by the first ratio, and as second parameter G2 measures the transmission input speed. From the difference between the first and second parameters a time variation is determined for two consecutive values. The electronic control device detects an error of the releasing clutch or brake when the the difference after load take-up does not increase. This solution offers the advantage that with the aid of the two parameters, it is possible to assess whether the gearshift proceeds methodically. In case of an error, the gearshift is discontinued and the automatic gearbox remains in the initial gear.
In one embodiment, it is proposed that the first and second parameters be each surrounded by an envelope curve. An error exists when after the load take-up the envelope curves still overlap so that the values of the two parameters G1, G2 represent within the envelope curves the faulty area and values and outside the envelope curves the fault-free area. This embodiment offers the advantage that tolerances of the speed sensors are not immediately assessed as an error of the releasing clutch or brake.
In another embodiment, it is proposed that briefly increased slip on the input gears be detected when the values of the first parameter G1 are below the second parameter G2.
BRIEF DESCRIPTION OF THE DRAWING(S)
An embodiment is illustrated in the figures that show:
FIG. 1 is a system diagram of an automatic gearbox;
FIG. 2 is a clutch-brake logic of the automatic gearbox;
FIG. 3 is an ideal time variation of the first and second parameters for an upshift;
FIG. 4 is an ideal time variation of the first and second parameters for a downshift;
FIG. 5a is a faulty time variation for an upshift, 1st case;
FIG. 5b is a faulty time variation for an upshift, 2nd case; and
FIG. 6 is a diagram, number of the successful/unsuccessful test conditions.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
In FIG. 1 is shown an automatic gearbox 2. The automatic gearbox 2 is comprised of a hydrodynamic converter 7, a combined planetary transmission 11 with differential 12, a hydraulic control device 4 and a electronic control device 5. An internal combustion engine 1 drives the automatic gearbox 2 via input shaft 6. An electronic engine control device 3 controls or regulates the internal combustion engine 1. The input shaft 6 is non-rotatably connected with the hydrodynamic conve
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patent: 5839083 (1998-11-01), Sugiyama
Arthur Gertrude
Cuchlinski Jr. William A.
ZF Friedrichshafen AG
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