Planetary gear transmission systems or components – Planet pinion is friction gear – Variable speed ratio
Patent
1998-08-24
1999-11-16
Wright, Dirk
Planetary gear transmission systems or components
Planet pinion is friction gear
Variable speed ratio
475215, F16H 3708, F16H 1552
Patent
active
059848200
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a motor vehicle transmission having a continuously variable transmission ratio and comprising a transmission input shaft, a first input shaft, a transmission output shaft, a first transmission stage with continuously variable transmission ratio and a second transmission stage configured as a summing transmission, the transmission input shaft being connected on the one hand side with the input of the first transmission stage and on the other hand side via a first clutch with a first input of the second transmission stage, the output of the first transmission stage, further, being connected on the one hand side with a second input of the second transmission stage and, on the other hand side via a second clutch with the transmission output shaft constituting also the output of the second transmission stage, the first transmission stage being, particularly, configured as a friction wheel epicyclic transmission in which two bodies contact each other in an area. The invention is particularly related to such transmissions in which by switching two clutches two modes of operation may be set being characterized by a synchronous transition.
A transmission of the afore-mentioned kind is disclosed in a conference report "4. Aachener Kolloquium, Fahrzeug- und Motor-entechnik '93", pages 607-622. The transmission in question has become well-known in the art under the manufacturer's denomination "TOROTRAK".
In a "TOROTRAK" transmission two toroidal frictional bodies, so-called globoides are arranged non-rotationally on an input shaft. Between the two toroidal frictional bodies a toothed disk of a toothed chain is arranged rotationally which, at its two radial outer surfaces is also configured as a toroidal frictional body. Between the two opposing toroidal frictional surfaces of the non-rotational and the rotational toroidal frictional bodies, respectively, frictional transmission bodies are arranged at a distance from the axis which contact the two frictional surfaces of the toroidal frictional bodies. By tilting these frictional transmission bodies relative to the direction of the axis, the contact point on the respective toroidal frictional bodies may be adjusted in a radial direction so that a continuously variable transmission ratio is achieved. The toothed disk, therefore, rotates at a speed which may be adjusted continuously with respect to the speed of the input shaft. The transmission ratio may be varied between 2.0 and 0.5, corresponding to a gear ratio spread of 4. The transmission may be operated in a certain range (i<1) such that the speed is converted into faster speeds. Transmission ratios being smaller than 0.5 may not be achieved due to the specific design of that transmission because the frictional transmission bodies would have to be arranged to steep with respect to the direction of the axis.
An output shaft is arranged parallel to the input shaft. The output shaft has two axially neighbored hollow shaft sections, a first of which supporting the second pulley of the chain drive as well as the sun gear wheel of a planetary gear set. The other hollow shaft section is connected with the arm of the planetary gear set whereas the ring gear wheel is connected to the output shaft extending through the two hollow shaft sections.
The first hollow shaft section is adapted to be connected with the output shaft via a first clutch, whereas the second hollow shaft section is adapted to be connected to a toothed wheel via a second clutch, the toothed wheel meshing with a corresponding fixed wheel on the transmission input shaft via a fixed transmission ratio.
In a first mode of operation the first clutch is closed and the second clutch is opened. Hence, the variator drives the sun gear wheel and the input shaft drives the arm of the planetary gear set via the fixed transmission, the planetary gear set, in this instance, acting as a summing gear. The output of the planetary gear train, i.e. the ring gear wheel, drives the output shaft.
In a second mode of opera
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G. Niemann, H. Winter, Maschinen-elemente, 1986, pp. 192, 193, Tokyo.
G.B. Soar, C.J. Greenwood, 4.Aachener Kolloquium, Fahrzeug-und Motorentechnik, 1993, pp. 607-622.
Kircher William B.
Wright Dirk
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