Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Patent
1998-01-09
2000-06-27
Zanelli, Michael J.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
701 29, F16H 6112
Patent
active
060817607
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for monitoring a gearshift process, in particular that of an automatic transmission, where a (disengaging) gearshift element belonging to a first transmission ratio is opened, and an (engaging) shift element belonging to another transmission ratio is closed.
BACKGROUND OF THE INVENTION
In exclusively electronically controlled powershift transmissions, after a load take up by the engaged gearshift element, it must be checked whether the disconnected gear-shift element has also reliably disengaged. This can be done by monitoring the slip that occurs on the old gearshift element. The slip is calculated according to a turbine speed and an output speed. If, after a certain period of time, no slip results after the switching torque has been impressed on the shift element to be engaged, the old gear is retained in order to prevent a blockage of the transmission (EP-A 0 436 977).
For adjusting the hydraulic pressure in a shift element of an automatic transmission, DE-A 32 05 767 has disclosed a method in which the input speed and the output speed of the transmission are determined, and the pressure is adjusted so that the reduction ratio of the transmission during a change of gear follows a preset time function. The whole shifting operation preferably takes place in two steps wherein the pressure is controlled up to a free-wheel point, that is, the point at which the friction elements coordinated with the old gear disengage, and thereafter follows the regulation to a preset reduction ratio or a change of the reduction ratio. If the free-wheel point in the transmission is not reached, a time control ensures that the pressure is raised in a ramp-like manner until reaching the free-wheel point.
The effects upon the output torque, which result when the old shift element does not disengage, in particular are the following:
During a high engine torque, there is the danger of the torque on the transmission output falling to a very low value. This effect is especially negative, for example, in the case of an overtaking operation where the full engine power is needed or expected. During a slight engine torque, there results, instead of a positive traction torque, a substantially equally strong thrust torque. Especially on a smooth road, this could lead to the blocking of the wheels at least when the full pressure would be given to the shift element to be engaged in case the time step is exceeded.
SUMMARY OF THE INVENTION
This invention is based on the problem of indicating ways by which it is possible to check, during a gearshift, whether the old shift element to be disengaged has reliably opened and the new shift element to be engaged has reliably closed.
Other features essential to the invention and the advantages resulting therefrom are to be understood from the description that follows of several methods for the solution of the stated problem.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
In a first method, the start of a gearshift operation is established by comparing the actual change in transmission ratio (i=n.sub.an
.sub.ab of the transmission) with a stored, gear-dependent, required change in the transmission ratio. In case of divergences that are outside a tolerance band, a fault condition is detected. The actual transmission ratio is here determined from the ratio of the input and output speeds of the transmission parts to be engaged. The required change in transmission ratio results as a function of the actual transmission ratio, of the transmission ratio of the new gear and the time.
In another method, according to the invention, the difference in the speed of rotation on the new shift element is monitored. The start of a gearshift is established by comparing the change of the actual difference in the speed of rotation on the new shift element with a required change of difference in the speed of rotation. In the case of divergences which are outside a tolerance band, a fault condition is detected. The actual difference in the speed of rotation is determined from the di
REFERENCES:
patent: 4611507 (1986-09-01), Burkel et al.
patent: 5129287 (1992-07-01), Asada et al.
patent: 5142945 (1992-09-01), Shimanaka
patent: 5182969 (1993-02-01), Goto et al.
Dreibholz Ralf
Frotscher Gerd
Staiger Kai
Zanelli Michael J.
ZF Friedrichshafen AG
LandOfFree
Error recognition process for automatic gear boxes transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Error recognition process for automatic gear boxes transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Error recognition process for automatic gear boxes transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1792247