Epicyclic drive with unified planet assemblies

Abstract

An epicyclic drive has its planet gears integrated into separately built planet assemblies. Each planet assembly, in addition to its planet gear, includes a pin which extends through the planet gear and an antifriction bearing located between the gear and the pin. The outer raceways for the bearing are machined into the gear, whereas the inner raceways are machined into the pin. The bearing also has rolling elements organized in two rows between the inner and outer raceways. The pins have mounting ends which lie beyond the ends of the planet gear to anchor the planet assembly in a carrier. Seals fit into the planet gear and around the pin and retain grease within the bearing and prevent oil that lubricates the teeth of the gears from entering the bearing and deteriorating the grease. The bearing, inasmuch as it is assembled separately, is set with considerable precision, preferably in preload, so the planet gear does not skew with respect to sun and ring gears with which it meshes during operation at the epicyclic drive

What is claimed is:  
     
         1 . A planet assembly for an epicyclic drive, said planet assembly having an axis and comprising: 
 a pin having first and second inner raceways located around and presented away from the axis;    a planet gear located around the pin and carrying first and second outer raceways, the first outer raceway being present toward the first inner raceway and the second outer raceway being presented toward the second inner raceway;    first rolling elements organized in a row between the first raceways and second rolling elements organized in a row between the second raceways;    and seals fitted around the pin and to the planet gear to create dynamic fluid barriers that isolate the rolling elements and raceways from the exterior of the gear.    
     
     
         2 . A planet assembly according to  claim 1  wherein the first raceways are oblique to the axis and are inclined in the same direction with respect to the axis; and wherein the second raceways are also oblique to the axis and inclined in the same direction with respect to the axis, with the inclination of the second raceways being opposite the inclination of the first raceways, whereby the first rolling elements will transmit axial loads in one direction and the second rolling elements will transmit axial loads in the opposite direction.  
     
     
         3 . A planet assembly according to  claim 2  wherein the first and second raceways are tapered and the first and second rolling elements are tapered rollers; and wherein the fist and second raceways taper downwardly toward each other.  
     
     
         4 . A planet assembly according to  claim 3  wherein the pin further has a thrust rib at the large end of the first inner raceway to prevent the first rollers from moving up the first raceways and a seat extended beyond the large end of the second inner raceway; and further comprising a rib ring fitted over the seat to prevent the second rollers from moving up the second raceways, whereby the axial position of the rib ring on the seat controls clearances or the absence of clearances between the tapered rollers and the raceways.  
     
     
         5 . A planet assembly according to  claim 1  wherein the pin is a unitary structure.  
     
     
         6 . A planetary assembly according to  claim 1  wherein the pin includes a core and a sleeve which is located around the core, and the inner raceways are on the sleeve.  
     
     
         7 . A method of assembling the planetary assembly of  claim 4 , said method comprising: placing the first tapered rollers along one of the first raceways; fitting the pin and gear together such that the first rollers are between the first inner and outer raceways and along the thrust rib; placing the second tapered rollers between the second raceways, advancing the rib ring over the seat until the bearing has a desired setting; and securing the rib ring to the pin.  
     
     
         8 . The method according to  claim 7  wherein the step of securing the rib ring includes welding the rib ring to the pin.  
     
     
         9 . The method according to  claim 7  wherein the step of placing the first tapered rollers along one of the first raceways includes placing the rollers along the first inner raceway.  
     
     
         10 . In an epicyclic drive including a sun gear, a ring gear, and a carrier having a pair of end members, the improvement comprising: 
 at least one pin having first and second ends anchored in the end members of the carrier;    a planet gear located around the pin and being engaged with the sun and ring gears;    an antifriction bearing located between pin and planet gear and including first and second inner raceways carried by the pin, first and second outer raceways carried by the planet gear and presented toward and located opposite the first and second inner raceways, respectively, first rolling elements arranged in a row between the first raceways, second rolling elements arranged in a row between the second raceways:    a grease in the bearing;    and seals located around the pin and along the gear to form fluid barriers at the ends of the gear, so that the bearing and grease are isolated from the sun and ring gears and from a lubricant for such gears.    
     
     
         11 . The combination according to  claim 10  wherein the carrier further comprises separators extending between the end members to form at least one pocket in which the planet gear rotates.  
     
     
         12 . The combination according to  claim 10  wherein the first raceways are oblique to the axis and are inclined in the same direction with respect to the axis; and wherein the second raceways are also oblique to the axis and inclined in the same direction with respect to the axis, with the inclination of the second raceway being opposite the inclination of the first raceways, whereby the first rolling elements will transmit axial loads in one direction and the second rolling elements will transmit axial loads in the opposite direction.  
     
     
         13 . The combination according to  claim 12  wherein the first and second rolling elements are tapered rollers; and wherein the first and second raceways taper downwardly toward each other.  
     
     
         14 . The combination according to  claim 13  wherein the pin further has a thrust rib at the large end of the first inner raceway to prevent the first rollers from moving up the first raceways and a seat extended beyond the large end of the second raceway; and wherein the bearing further comprises a rib ring fitted over the seat to prevent the second rollers from moving up the second raceways, whereby the axial position of the rib ring on the seat controls the setting of the bearing.  
     
     
         15 . A planet assembly for an epicyclic drive, said planet assembly comprising: 
 a pin provided with mounting ends and first and second tapered inner raceways located between the mounting ends and tapering in opposite directions downwardly toward each other, the pin further having a thrust rib projecting beyond the large end of the first inner raceway and a seat extending axially beyond the large end of the second inner raceway;    a planet gear located around the pin and having first and second tapered outer raceways presented toward and located opposite the first and second inner raceways, respectively, the gear being narrower then the pin is long such that the mounting ends of the pins are located beyond the ends of the gear;    first tapered rollers located between the first inner and outer raceways and against the thrust rib, whereby the thrust rib prevents the first rollers from moving up the first raceways;    second tapered rollers located between the second tapered raceways;    a rib ring fitted over the seat on the pin and against the second tapered rollers to prevent the second rollers from moving up the second raceways.    
     
     
         16 . A planet assembly according to  claim 15  wherein the rib ring is welded to the pin.  
     
     
         17 . A planet assembly according to  claim 15  wherein the inner raceways are machined on the pin and the outer raceways are machined into the planet gear.  
     
     
         18 . A planet assembly according to  claim 15  and further comprising a first seal located in the planet gear and around the thrust rib on the pin, and a second seal located in the planet gear and around the rib ring.  
     
     
         19 . A planet assembly according to  claim 15  wherein the pin comprises a core and a sleeve located around the core; wherein the inner raceways thrust rib and ring seat are on the sleeve; and wherein the core projects beyond the ends of the sleeve and forms the mounting ends of the pin.  
     
     
         20 . A method of assembling the planetary assembly of  claim 15 , said method comprising: placing the first tapered rollers along one of the first raceways; fitting the pin and gear together such that the first rollers are between the first inner and outer raceways and along the thrust rib; placing the second tapered rollers between the second raceways; advancing the rib ring over the seat until the bearing has a desired setting, and securing the rib ring to the pin.