Dual-Power Transmission Device for a Twin-Rotor Helicopter

Abstract

A dual-power transmission device includes: a first output shaft secured rotatably in a housing and having a first rotor coupling portion extending outwardly of the housing; a second output shaft disposed to surround the first rotor coupling portion, secured rotatably in the housing, and having a second rotor coupling portion extending outwardly of the housing; first and second bevel gears mounted respectively on the first and second output shafts; first, second and third thrust bearings for positioning the first and second bevel gears in the housing; and first and second input units respectively coupled to first and second power sources and each meshing with the first and second bevel gears.

1 . A dual-power transmission device for a twin-rotor helicopter, said dual-power transmission device being adapted to be coupled to first and second power sources and comprising:
 a housing;   a first output shaft having a first gear mounting portion secured rotatably in said housing and a first rotor coupling portion extending from said first gear mounting portion and outwardly of said housing, said first output shaft being rotatable about a first axis;   a second output shaft disposed to surround said first rotor coupling portion of said first output shaft and having a second gear mounting portion secured rotatably in said housing and a second rotor coupling portion extending from said second gear mounting portion and outwardly of said housing, said second output shaft being rotatable about the first axis;   a first bevel gear mounted on and rotatable coaxially with said first gear mounting portion;   a second bevel gear mounted on and rotatable coaxially with said second gear mounting portion;   first, second and third thrust bearings, said first thrust bearing being disposed between said housing and   said first bevel gear, said second thrust bearing being disposed between said first and second gear mounting portions, said third thrust bearing being disposed between said housing and said second bevel gear, said first, second and third thrust bearings cooperating to position said first and second bevel gears in said housing such that said first and second bevel gears are spaced apart from each other along the first axis and form a gear meshing space therebetween;   a first input unit secured to said housing, rotatable about a second axis that intersects the first axis, adapted to be coupled to the first power source, and having a first bevel gear section extending into said gear meshing space and meshing with said first and second bevel gears; and   a second input unit secured to said housing, rotatable about the second axis, adapted to be coupled to the second power source, and having a second bevel gear section extending into said gear meshing space and meshing with said first and second bevel gears.   
   
   
       2 . The dual-power transmission device as claimed in  claim 1 , wherein:
 said first gear mounting portion has a diameter larger than that of said first rotor coupling portion, thereby configuring said first output shaft with an annular shoulder at a junction of said first gear mounting portion and said first rotor coupling portion;   said first gear mounting portion is formed with a first gear mounting flange that extends in radial outward directions relative to the first axis;   said second gear mounting portion has one end proximate to said annular shoulder of said first output shaft and formed with a second gear mounting flange that extends in radial outward directions relative to the first axis;   said first bevel gear is mounted on said first gear mounting flange; and   said second bevel gear is mounted on said second gear mounting flange.   
   
   
       3 . The dual-power transmission device as claimed in  claim 2 , wherein:
 said housing has a first housing surface confronting said first bevel gear, and a second housing surface confronting said second bevel gear;   said first thrust bearing is disposed between said first housing surface and said first bevel gear;   said second thrust bearing is disposed between said first and second gear mounting flanges; and   said third thrust bearing is disposed between said second housing surface and said second bevel gear.   
   
   
       4 . The dual-power transmission device as claimed in  claim 3 , wherein said housing includes a lower housing part formed with said first housing surface, an upper housing part formed with said second housing surface, and an intermediate housing part disposed between and coupled to said lower and upper housing parts, said first and second rotor coupling portions extending outwardly of said housing through said upper housing parts,
 said first and second input units extending outwardly of said housing through said intermediate housing part.   
   
   
       5 . The dual-power transmission device as claimed in  claim 1 , further comprising:
 a first needle bearing disposed between said first gear mounting portion and said housing;   a second needle bearing disposed between said first and second gear mounting portions; and   a third needle bearing disposed between said second gear mounting portion and said housing.   
   
   
       6 . The dual-power transmission device as claimed in  claim 1 , wherein said first input unit further has a first shaft section extending from said first bevel gear section along the second axis and outwardly of said housing, and said second input unit further has a second shaft section extending from said second bevel gear section along the second axis and outwardly of said housing,
 said dual-power transmission device further comprising a first ball bearing disposed between said housing and said first shaft section, and a second ball bearing disposed between said housing and said second shaft section.   
   
   
       7 . The dual-power transmission device as claimed in  claim 6 , further comprising a first one-way clutch adapted for coupling said first shaft section to the first power source, and a second one-way clutch adapted for coupling said second shaft section to the second power source. 
   
   
       8 . The dual-power transmission device as claimed in  claim 1 , wherein the second axis is substantially perpendicular to the first axis. 
   
   
       9 . The dual-power transmission device as claimed in  claim 1 , wherein said first and second input units are disposed at diametrically opposite positions relative to the first axis, and drive said first and second bevel gears to rotate simultaneously in opposite directions.