Planetary gear transmission systems or components – Planet periphery surrounds axis of interacting gear – Wabbler transmission
Reexamination Certificate
1999-08-09
2001-07-17
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
Planet periphery surrounds axis of interacting gear
Wabbler transmission
C475S170000
Reexamination Certificate
active
06261199
ABSTRACT:
FIELD OF THE INVENTION
The invention is in the field of power transmissions and gear boxes having non-back drive and lock-up features.
BACKGROUND OF THE INVENTION
Non-back-drivable gearboxes function to transmit torque from a high speed, low torque input shaft to a low-speed, high torque output shaft and does not transmit torque from the output shaft back to the input shaft. Conventional non-back-drivable power transmissions include worm gears and lead screws. Worm gearing is used for obtaining large speed reductions between non-intersecting shafts. The velocity ratio of worm gearing is the ratio between the number of teeth on the gear and the number of threads on the worm. The non-reverse drive characteristics of worm gearing relies on friction. It is required for non-back drive transmissions to have the power lost to friction equal to or greater than the output power. The theoretical maximum efficiency of a conventional non-back-derivable worm gearing is 50 percent.
Power transmissions having spur gears are disclosed in the prior art. W. J. Wallace Jr. in U.S. Pat. No. 2,178,443 discloses a non-reversible motion transmission mechanism having drive and driven shafts connected to planetary spur gears which are moved outwardly into engagement with a fixed ring spur gear when torque is applied to the driven shaft. J. A. Gilder in U.S. Pat. No. 2,995,226 discloses a reverse torque lock mechanism having a moving lock member that is forced into engagement with a fixed ring gear when reverse torque is applied to an output or driven shaft.
SUMMARY OF THE INVENTION
The invention is a non-back drive power transmission that utilizes a power transmitting gear to transmit torque from a high speed input shaft to a low speed output shaft and prohibits the transmission of torque from the output shaft back to the input shaft. The transmission does not rely on friction between gears or parts to predicate its non-back drive or lock-up function. The non-back drive power transmission is applicable to aircraft controls surfaces, conveyor systems, passenger and freight elevators, boat trailer hoists, sail boat rigging systems, carnival rides, robot joints, high-tension cable tightening systems, door counterbalancing systems, and power transmitting apparatus that requires one-way drives with no back drive.
The non-back drive power transmission has a case with a stationary internal gear having spur teeth circumferentially located around the inside of the case. End plates attached to opposite sides of the case enclose the space within the internal gear. An input shaft rotatably mounted on one end plate supports an eccentric member which rotatably supports an external gear having spur teeth adapted to mesh with the teeth of the internal gear. The external gear is smaller in diameter then the diameter of the internal gear and has fewer teeth than the internal gear. The internal and external gears have complementary teeth with segments of the teeth that mesh when the external gear is turned around the fixed gear. The external gear is drivably connected with an output shaft rotatably mounted on the other end plate. The internal gear has an inside circumferential surface or track spaced inwardly from the teeth. The input shaft has an arm with a roller that rides on the track to maintain with the eccentric member segments of the external gear teeth in meshing engagements with fixed teeth on the case as the external gear moves around the internal gear. Torque applied to the output shaft is not transmitted to the input shaft as the roller holds the external gear in locking engagement with the fixed gear.
REFERENCES:
patent: 2014316 (1935-09-01), Farrell
patent: 2178443 (1939-10-01), Wallace, Jr.
patent: 2475504 (1949-07-01), Jackson
patent: 2883017 (1959-04-01), Jungles
patent: 2995226 (1961-08-01), Gilder
patent: 3965773 (1976-06-01), Bert et al.
patent: 4016780 (1977-04-01), Baranyi
patent: 4512213 (1985-04-01), Newton
patent: 4621543 (1986-11-01), Gabilondo
patent: 4640154 (1987-02-01), Osborn
patent: 4762025 (1988-08-01), Lew
patent: 4994005 (1991-02-01), Rennerfelt
patent: 5616095 (1997-04-01), Pruitt
patent: 5759130 (1998-06-01), Woytaszek
Lewis Tisha D.
Marmor Charles A
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