Planetary gear transmission systems or components – Planet pinion is friction gear
Patent
1997-09-26
2000-03-21
Marmor, Charles A.
Planetary gear transmission systems or components
Planet pinion is friction gear
475346, 475334, F16H 1306
Patent
active
060396687
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a planet gear comprising a central, rotatable input axle, a flexible outer ring, which under elastic deformation surrounds and presses at least three planet wheels in the form of rollers radially up against a centrally-disposed sun axle which extends axially in line with the input axle, said planet wheels having central holes and being rotatably mounted on stays, the diamters of which are smaller than the holes in the planet wheels, and where the centre-lines of the stays are parallel with the sun axle.
From U.S. Pat. No. 1,985,645 there is known a planet gear with a driving sun axle which is rotatably mounted in a support by means of bearings and is controlled against axial movement by a flange and a collar. A driven element is concentric with an extended cylindrical part of the driving sun axle and is integral with a shaft through which the gear can be connected to a machine.
In contact with the cylindrical part of the sun axle there is a first series of planet wheels disposed at a mutual distance, and radially outside there is provided a second series of planet wheels which are in contact with the first series of planet wheels and the inside circumference of a flexible outer ring. Each series preferably comprises an even number of planetary wheels, where the radially internal first series is of the same diameter. The radially external second series preferably comprises two planet wheels which have a slightly greater diameter than the remaining radially external planet wheels which, as a consequence of the even number of planet wheels, are disposed on diametrically-opposite sides of the sun axle. The outer ring is preferably configured with its internal diameter slightly smaller than the overall dimension which is measured across the planet wheels, whereby the outer ring in the assembled state is slightly deformed and presses the two planet wheels with the slightly greater diameter towards the centre of the sun axle, and causes all of the remaining planet wheels to enter into frictional engagement with each other and with the sun axle.
The outer ring forms a friction-providing surface for the driven element and is in driving engagement herewith by means of grooves in the driven element, said grooves having a sliding engagement with complementary keys on the outer ring, in that the keys move radially into the grooves during the rotation of the gear.
The function of the planet gear is explained thus: The external part of the outer ring's keys, which stand opposite to the planet wheel with the slightly greater diameter, are pressed to the bottom of the corresponding groove without deforming the driven element, which can be made as rigid as possible for the correct transmission of the force, while the outer ring's keys opposite the space between two of the remaining planet wheels in the radially external set are moved slightly inwards.
At least one of the planet wheels with the slightly larger diameter is preferably mounted in a rotatable manner on a firm support, such as a bearing, in order to absorb the planet wheel's reaction to the torque.
In the publication there is not described any radial displacement of the at least one planet wheel which has the slightly larger diameter and is mounted on a firm support. In a figure is shown a slot of uniform thickness around the bearing for the disclosed firmly supported planet wheel, which slot must be understood to be incorrectly drawn, in that the flexible outer ring will attempt to assume a circular shape and hereby press the bearing inwards.
If the disclosed planet wheel with the slightly larger diameter is deliberately meant to be suspended in a radially displaceable manner, a ramp effect which is described in the following could not be achieved, in that a greater deformation of the flexible outer ring--as a consequence of an outwardly-directed movement of the disclosed planet wheel--will be cancelled by a smaller deformation at the remaining planet wheels in the radially external set of planet wheels.
Since the radially internal set o
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patent: 4950110 (1990-08-01), Suzuki
patent: 5779589 (1998-07-01), Futterer
Lars Barthold Nielsen
Lund Scott
Marmor Charles A.
Orla Kragh Jensen
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