Planetary gear transmission systems or components – Planetary gearing or element – Floating or flexible coupling or support
Reexamination Certificate
1999-08-20
2001-03-27
Wright, Dirk (Department: 3681)
Planetary gear transmission systems or components
Planetary gearing or element
Floating or flexible coupling or support
Reexamination Certificate
active
06206800
ABSTRACT:
BACKGROUND
The present disclosure relates to gears and planetary gear assemblies for use in connection with drive shafts. More particularly, the present disclosure relates to a gear train assembly having a universally adaptable carrier and a swing arm assembly which allow for multiple gear ratios simply by varying the size and position of the planetary and sun gears.
TECHNICAL FIELD
There are a variety of machine elements available for transmitting power from one driveshaft to another; one such machine element is a gear. Among the many types of gears, the most common are spur gears, helical gears, bevel gears and worm gears. When two gears mesh, the shape or profile of the teeth of each gear must be such that the common normal at point of contact between two teeth always passes through a fixed point, e.g., pitch point, on the line of centers. This is known as the fundamental law of gearing as described in
Kinematics and Dynamics of Machinery
by C. E. Wilson, J. P. Sadler and W. P. Mitchels.
Gears may be assembled in a wide variety of arrangements which can be generally classified into three main categories: 1) gears fixed on an axis, e.g., simple gear trains where each shaft rotates about a fixed axis, compound gear trains where two or more gears are keyed to the same shaft and reverted gear trains where the input and output gears of a compound train are coaxial; 2) epicyclic gear trains where the center of the outer or planet gear moves about the center of the center or sun gear while the angular velocities of both gears maintain a fixed ratio; and 3) planetary gear trains where two or more independent coaxial gears are meshed commonly with a number of similar, equally spaced gears or planets mounted on intermediate or secondary shafts which are, in turn, fixed to a common carrier.
Due to their simplicity, planetary gear trains are readily adapted to automatic control and are designed to change ratios simply by using electrically or hydraulically operated band breaks (or other breaking mechanism) to keep one or more of the gears stationary. Other planetary trains operating with fixed gear ratios are selected for their compact design and high efficiency.
The simple planetary gear train consists of a sun gear in the center, at least one planet gear, a planet carrier and an internal ring gear. Generally, the sun gear, ring gear and planet carrier all rotate about the same axis and the planet gear (or gears) is mounted on a shaft that turns in a bearing mounted to the planet carrier, i.e., the planet gear meshes with both the sun gear and the ring gear. Additional planet gears positioned about a sun gear are kinematically redundant in terms of speed and velocity, i.e., they play no role in kinematic analysis and simply share the load and give better balance to the overall gear assembly. However, it is known that better balancing of gear tooth loads and inertia forces will result if two or more planets mesh with each ring gear.
In most cases, planetary gear trains are used to obtain a speed increase or speed reduction. For example, if a sun gear rotates with the input shaft and the carrier rotates the output shaft of a planetary gear assembly, the gear assembly would typically operate as a speed reducer. Other applications include a reversal in direction and a differential effect.
Numerous planetary gearing assemblies have been proposed in the past for various applications. However, none of these gear assemblies are designed with a universally adaptable carrier and a swing arm assembly which allow for multiple gear ratios simply by varying the size of the planetary and sun gears. For example: U.S. Pat. No. 5,800,302 to Werre; U.S. Pat. No. 5,842,947 to Weilant; U.S. Pat. No. 5,662,545 to Zimmerman et al.; U.S. Pat. No. 5,498,208 to Braun; and U.S. Pat. No. 5,429,558 to Lagarde, all relate to types of planetary gearing assemblies for use with various devices, e.g., transmissions, screw drivers and/or sprinklers. For the most part, the prior art devices are overly complicated, difficult to assemble and require re-tooling in order to change gear ratios.
Thus, there exists a need to develop a gear assembly in which the gear ratios can be modified in a simple, quick and effective manner without the need for retooling, changing carriers or remounting the input and/or output shafts.
SUMMARY
The present disclosure relates to a gear train assembly which includes an outer ring gear, a first gear or drive gear and at least one planetary or second gear which revolves about the first gear within the ring gear. The gear train assembly also includes a universal carrier having a plurality of mechanical interfaces, e.g., apertures or bushings, disposed thereon which anchor a first end of a support member or stanchion and a universal carrier cover having at least a complimentary plurality of mechanical interfaces disposed thereon which anchor a second end of the stanchion. A pivot assembly with a bushing mounts the second gear to a swing arm which is coupled to the stanchion. Preferably, the gear train assembly also includes a spacer for anchoring a distal end of the bushing to the stanchion.
In one embodiment, the mechanical interfaces of the universal carrier and the carrier cover are positioned so as to accommodate a plurality of pivot assemblies and corresponding stanchions at multiple positions. Preferably, the gear ratio between the first and second gears can be selectively altered without changing the carrier or carrier cover, e.g., by manipulating the size of one of the first gear and/or the ring gear and the size and position of the pivot assemblies and affixing the stanchions to correlating mechanical interfaces on the carrier and the carrier cover.
Another embodiment includes a gear train assembly which has a drive gear, a ring gear and at least one selectively removable planetary gear assembly having a bushing which mounts a planetary gear to a swing arm which is coupled to a fixed stanchion. The gear train assembly also includes a carrier having a plurality of mechanical interfaces disposed thereon which anchor a first end of the stanchion of the planetary gear assembly and a carrier cover having at least a complimentary plurality of mechanical interfaces disposed thereon which anchor a second end of the stanchion of the planetary gear assembly. A plurality of planetary gear assemblies can be mounted between the universal carrier and carrier cover to mesh with the drive gear and the ring gear.
Preferably, the gear ratio between the drive gear and the planetary gear assemblies can be selectively altered by manipulating the size of one of the drive gear and/or the ring gear and the size and position of the planetary gear assemblies. The mechanical interfaces of the carrier and the carrier cover are positioned so as to accommodate multiple planetary gear assemblies in multiple positions.
In another embodiment, the gear train assembly includes a ring gear; a first gear having a first diameter and a plurality of second gears having a second diameter which revolve about the first gear within the ring gear. The gear train also includes a complimentary plurality of pivot assemblies each having a swing arm which couples at one end to one of the second gears and at an opposite end to a fixed stanchion. The swing arm is movable to compensate for manufacturing deviations in the first and second gears and the second gears and the ring gear and/or to compensate for changes in the input-to-output ratio.
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patent: 4
Dilworth & Barrese LLP
Thomson Industries Inc.
Wright Dirk
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