Planetary gear transmission systems or components – Planet periphery surrounds axis of interacting gear – Circumferentially spaced connector pins
Patent
1996-01-31
1997-12-16
Wright, Dirk
Planetary gear transmission systems or components
Planet periphery surrounds axis of interacting gear
Circumferentially spaced connector pins
F16H 128
Patent
active
056978685
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a planetary speed reduction unit of a gear type or a friction wheel type, including a single planet pinion or planet friction disk, and a single internal gear or a single internal frictional element having therein a friction inner circumference, which surrounds the planet pinion or the planet friction disk so as to provide a path for a planetary motion, and to be able to reduce a rotative input given thereto by an external rotative drive source or a built-in rotative drive source by a single reduction step at a large reduction ratio to thereby transmit a reduced rotative output to an output element or an output flange.
BACKGROUND ART
There have been several types of planetary speed reduction units, and several types of drive devices with a built-in reduction gear each formed by combining a motor and a reduction gear.
Although there has been a well-known mechanism employing an eccentric pin mechanism for linking a planet pinion that revolves for planetary motion to an output shaft or an output flange, there has been provided neither a mechanism employing a unique linking means including a floating, eccentric, fixed pin linking a planetary gear unit to an output flange concentric with the planetary gear unit nor a drive device with a built-in planetary speed reduction unit provided with a single planet pinion connected to a motor-driven element for rotation and revolution.
For example, U.S. Pat. No. 3,239,699 merely discloses a mechanism constructed by installing a motor and a Harmonic Drive reduction gear in an integral housing.
U.S. Pat. No. 4,678,952 merely discloses a drive mechanism formed by combining a motor and a Harmonic Drive speed reduction unit, and provided with a brake and a position encoder in the hollow central portion thereof.
U.S. Pat. No. 5,293,107 merely discloses an apparatus including, in combination, a motor having a hollow central portion and provided with a non-eccentric planet pinion linked to an output flange, and a planet pinion.
A well-known Rota-Vector RV reduction gear is a planetary speed reduction unit provided with two large planet pinions that rotate and revolve in an internal gear larger than the planet pinions. In the RV reduction gear, the planet pinions are connected to an output flange with an eccentric crankpin arrangement, and the eccentric crankpin is rotated by a torque relative to an output shaft. An external torque is applied to the eccentric crankpin by a drive gear concentric with the eccentric crankpin. The reduction gear may be provided with a central through-hole. Since this type of RV reduction gear is not constructed so as to be internally provided with a drive element that generates rotative input, but is an individual reduction gear, a separate drive motor necessarily needs to be connected to the input element of the RV reduction gear to give an input to the RV reduction gear. Further, a drive system formed by combining an RV reduction gear and a drive motor is relatively expensive.
A well-known Cyclo reduction gear is similar to the afore-mentioned RV reduction gear, except that a plurality of straight pins are extended through oversized holes to be fitted in an output flange and two planet pinions. The oversized holes permit the revolving or orbiting motions of the planet pinions while keeping contact with the straight pins. The Cyclo reduction gear, similarly to the RV reduction gear, is an individual reduction gear and needs to be driven by a separate drive motor. In the Cyclo reduction gear, the revolution of each planet pinion is transmitted to the output shaft through straight pins in contact with the circumferential surfaces of cylindrical holes of a curved plate, each of the cylindrical holes having a diameter larger than that of the straight pin. However, the load capacity of the Cyclo reduction gear is relatively small because the straight pins are in a point contact with the circumferential surfaces of the cylindrical holes.
A well-known Dojen drive has two planet pinions integrally coupled
REFERENCES:
patent: 2170951 (1939-08-01), Perry
patent: 2475504 (1949-07-01), Jackson
patent: 2656737 (1953-10-01), Lang
patent: 3239699 (1966-03-01), Ferrary
patent: 4183267 (1980-01-01), Jackson
patent: 4378623 (1983-04-01), Noguchi
patent: 4678952 (1987-07-01), Peterson et al.
patent: 4994005 (1991-02-01), Rennerfelt
patent: 5123883 (1992-06-01), Fukaya
patent: 5123884 (1992-06-01), Kondoh et al.
patent: 5293107 (1994-03-01), Akeel
Fanuc Ltd.
Wright Dirk
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