Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on...
Patent
1996-01-22
1997-09-30
Bonck, Rodney H.
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
192103F, B60K 4122, F16D 4802
Patent
active
056721323
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a regulation process for a continuously variable transmission.
Continuously variable transmissions have a pair of tapered discs on the input and output shafts, respectively. Between said pair of tapered discs extends a belt, chain or link conveyor which winds around the input and output shafts. Each pair of tapered discs consists of a first tapered disc firmly connected with a shaft and a second tapered disc movable in an axial direction. The input power is transmitted by friction contact between the traction roller and the tapered discs. The axial position of the second disc is changed by a hydraulic control mechanism. The effective diameter of the traction roller and thus transmission ratio are changed thereby.
DE-OS 39 14 792 has disclosed a motor vehicle drive where a clutch is situated between an engine and a continuously variable transmission. The purpose of the clutch is to secure the tapered discs and the traction roller against torque shock loads. To this end, the clutch pressure is selected according to the speed and load in a manner such that the transmissible torque of the clutch is smaller than that of the traction roller on the tapered discs. In this design it is disadvantageous that the actual behavior of the clutch is not detected. Therefore, the clutch must be loaded with a substantially higher pressure for reasons of security.
The problem to be solved by the invention is to control the clutch according to its actual condition.
According to the invention, the problem is solved by the fact that during operation the actual slip torque of the clutch is cyclically or anticyclically determined, the intensity of the torque pressure is compared with a characteristic curve and the comparison establishes a correction value used for adapting the characteristic curve.
The slip torque of the clutch is determined by gradually lowering the actual clutch pressure from a first pressure level to a second pressure level. The second pressure level is reached when a slight speed difference, such as 50 revolutions, appears on the clutch. The difference of the first pressure level minus the second pressure level indicates by what amount the first pressure level is above the slip limit of the clutch. A correction value results from said difference. The original characteristic curve is modified using said correction value. An input variable of the characteristic curve is the torque on the clutch, a dependent variable of the characteristic curve is the clutch pressure.
The slip torque of the clutch is determined with a firm time beat or with preset operation conditions. The preset operation conditions can be, for example, load position, engine speed or combinations of said operation parameters.
The solution according to the invention offers the advantage of detecting parameters on the transmission behavior of the clutch. Parameters of the clutch are, for example, scattering of the friction values due to manufacturing tolerances, change of the friction value as function of the temperature, change of the friction value during the operating life of the transmission and the pulling-away torque of a sticking clutch.
In one development of the invention, it is proposed that the correction value be updated upon each detection of the slip torque. Suddenly changing parameters, such as temperature, are detected hereby.
In another development of the invention, it is proposed that when in a preset number of correction values, the correction value exceeds a first positive limiting value of the pressure or falls below a second negative limiting value of the pressure, the last correction value is deposited in a permanent memory. The advantage obtained hereby is that slowly changing parameters, such as a change of friction value during the operating life or serial scattering, are taken into account. By storing the last correction value in a battery-buffered RAM, for example, it is obtained that after new a start of the vehicle, the last correction value immediately enters in the computation of the clutch pre
REFERENCES:
patent: 4433594 (1984-02-01), Smirl
patent: 4606446 (1986-08-01), Watanabe
patent: 4665773 (1987-05-01), Hiramatsu et al.
patent: 4829221 (1989-05-01), Grunberg et al.
patent: 4880094 (1989-11-01), Ohkumo
patent: 4958538 (1990-09-01), Yamashita et al.
patent: 4969545 (1990-11-01), Hayashi
patent: 5006092 (1991-04-01), Neuman et al.
patent: 5074166 (1991-12-01), Yamashita et al.
patent: 5098345 (1992-03-01), Van Vuuren
patent: 5211083 (1993-05-01), Hattori et al.
Bonck Rodney H.
ZF Friedrichshafen AG
LandOfFree
Continuously variable transmission regulation process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Continuously variable transmission regulation process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuously variable transmission regulation process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2253662