Planetary gear transmission systems or components – Planetary gearing or element – Floating or flexible coupling or support
Patent
1998-09-17
2000-07-11
Marmor, Charles A
Planetary gear transmission systems or components
Planetary gearing or element
Floating or flexible coupling or support
475319, F16H 5708, F16H 344
Patent
active
060865040
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a planetary gear and a clutch-brake arrangement, preferably for a continuously variable automatic transmission.
BACKGROUND OF THE INVENTION
Continuously variable automatic transmissions, hereinafter designated as CVT, consist of the following units: starting unit, forward/reverse drive unit, variator, intermediate shaft and differential. Such CVT's are usually driven by an internal combustion engine, via an input shaft, such as a crankshaft. As starting unit serves either a starting clutch or a hydrodynamic converter. The forward/reverse drive unit serves for the reversal of direction of rotation of the input shaft for the reverse drive. The forward/reverse drive unit is mostly designed as a planetary reversing gear. The latter consists of at least one sun gear, several planets, one ring gear, one brake and one clutch of multi-disc design. The variator consists of two pairs of cone pulleys and one belt. Each pair of cone pulleys, in turn, consists of one first cone pulley half stationary in its axial direction and one second cone pulley movable in axial direction. The belt, such as a thrust link conveyor, extends between the pairs of cone pulley halves. By the adjustment of the second cone pulley half the drive radius of the belt and thus the ratio of the CVT is adjusted.
A CVT, having a forward/reverse driver unit, was made known in the Automobiltechnischen Zeitschrift 96 (1994) 6, page 380, FIG. 3. Here a first shaft driven by the impeller of the hydrodynamic converter drives planetary gears connected by a common first planet spider. Each planetary gear is rotatably mounted upon a stud. On the one hand, the planetary gears mesh with a sun gear located upon a second shaft and, on the other hand, with a ring gear. By a brake of a multi-disc design, the ring gear can be fixed against a stationary wall such as the transmission housing. The second planet spider is connected by a clutch of the multi-disc design with the first cone pulley. When the clutch is closed, the planetary reverse gear revolves as a whole with the ratio of 1 and the same direction of rotation as the first shaft. When the brake is closed, a reversal of direction of rotation for the reverse drive takes place. The gears of the planetary reverse gear are usually helical. Due to the helical teeth of the planet/ring gear, axial forces appear on the ring gear. According to the cited prior art, the ring gear is supported in an axial direction either on the second planet spider connected with the clutch or on the stationary wall.
The problem on which the present invention is based is to further develop a brake having its internal disc carrier connected with a ring gear.
SUMMARY OF THE INVENTION
A first solution of the problem, according to the invention, consists in that a vertically disposed buffer disc is integrally connected with the ring gear. The inner radius of the buffer disc corresponds here substantially to the distance of the central axis of the first shaft to the central axis of the axis. The buffer disc is supported in an axial direction either on a stationary wall or on a first planet spider of the first shaft. The advantage obtained by this arrangement is that the point of support of the ring gear/buffer disc is closer to the central axis of the first shaft. A small peripheral velocity results herefrom. Another advantage consists in that by virtue of said shorter distance of the central axis of the first shaft to the point of support, the piston of the brake can be larger.
In a development of the invention, it is proposed that the buffer disc be supported in a radial direction by a surface on the inner diameter of the buffer disc and a surface of the stationary wall or of a shaft. Contrary to the prior art where the ring gear is exclusively supported by the planets, the advantage obtained hereby is that the ring gear is additionally supported in a radial direction.
A second solution of the problem, according to the invention, consists in that for an arrangement comprising one planetary gear in which the
REFERENCES:
patent: 2558738 (1951-07-01), Davis et al.
patent: 3097546 (1963-07-01), Kelbel et al.
patent: 3131582 (1964-05-01), Kelbel
patent: 3359833 (1967-12-01), Flinn
patent: 3669232 (1972-06-01), Rohweder et al.
patent: 4680979 (1987-07-01), Morishita et al.
patent: 5195389 (1993-03-01), Isozumi
patent: 5344370 (1994-09-01), Luyckx
ATZ Automobiltechnische Zeitschrift 96 (1994) 6 "Stufenloses Automatikgetriebe Ecotronic von ZF", Von Manfred Boos and Wolf-Ekkehard Krieg, pp. 378-384.
Marmor Charles A
Pang Roger
ZF Friedrichshafen AG
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