Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Patent
1999-03-04
2000-12-05
Marmor, Charles A
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
74336R, 731173, 731181, F16H 3100, F16H 5900, G01M 326, G01M 1900
Patent
active
061559482
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method for determining parameters of an electrohydraulically controlled automatic transmission by successively initiating on a final test bench, transmission gearshifts, and during the gear changes measuring a transmission input and transmission output speed and a transmission input as a function of time.
In electrohydraulic automatic transmissions deviations can occur within the transmission steps through different components or parts. The result of this is that in two identical vehicles, having identical automatic transmissions, the operating comfort can be very differently impaired. It has been sought in the practice to overcome said problem and to obtain a uniform operating comfort by using adaptive functions in an electronic transmission control. Thus, for example, DE Patent 34 36 190 proposes that an actual shifting time be compared with a theoretical shifting time. If the actual value differs from the theoretical value, the pressure level of a clutch involved in the gear change is changed by a presettable amount in the subsequent gearshift in the same gear shift stage. Now if the automatic transmission has to be changed in a customer service workshop, then the adaptive data, stored in the electronic transmission control, no longer coincides with the actual mechanical part of the automatic transmission.
SUMMARY OF THE INVENTION
The problem, to be solved by the invention, is to provide a quicker tying of an electronic transmission control to an automatic transmission.
According to the invention, the problem is solved by a method for determining parameters of an electrohydraulically controlled automatic transmission, on a final test bench, by initiating successive transmission gearshifts. During the gear changes, a transmission input and a transmission output speed and a transmission input and a transmission output moment and the curves thereof are measured in the course of time. From said measured values, a filling time, a charge pressure, a reaction time, a friction value of the discs and a pressurized fluid charge are determined as parameters of the automatic transmission for the clutch to be engaged during the change of gear. Said parameters are then deposited in a memory so that an electronic transmission control unit corrects, according to said parameters, the pressure level and the time of a rapid filling pressure, of the charge pressure and the pressure level of a shift pressure.
The solution, according to the invention, offers the advantage of detecting the whole tolerance chain, that is, control and transmission tolerances. Thereby greater tolerances of parts are possible, which makes possible a more economical production. These parameters, which characterize an existing automatic transmission, are then deposited in a memory. Thus the advantage resulting in comparison with the prior art is that in case of a great difference between actual and theoretical values, the electronic control unit more quickly synchronizes the actual and theoretical values. The electronic transmission control unit already issues an elevated pressure value based on the parameters.
In a development of this it is proposed that the filling time be determined, after initiating the gearshift, by filling the clutch to be engaged with a preset pressure level until the discs abut on each other. The clutch itself still transmits no moment so that the output moment is zero or almost zero.
In a further development it is proposed that the charge pressure be determined by raising the pressure level in the clutch until the moment transmitted by the clutch or the transmission output moment exceeds a limit value.
In a further development it is proposed that the friction value of the discs and the pressurized fluid charge be determined by raising the pressure level in the clutch to a theoretical value and determining the transmission output moment in addition.
In a further development, it is proposed that the reaction time be determined by measuring the time, after initiation
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Marmor Charles A
Pang Roger
ZF Friedrichshafen AG
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