Epicyclic gear system

Abstract

An epicyclic gear system has a sun gear, a ring gear located around the sun gear, and planet gears located between and engaged with sun and ring gears. In addition, it has a carrier including a carrier flange offset axially from the planet gears, carrier pins projecting from the carrier flange into the planet gears, and bearings between the planet gears and the carrier pins so that the planet gears rotate on the pins. Each bearing includes an inner race having tapered raceways presented away from the carrier pin, opposing tapered raceways on the ring gear, and tapered rollers organized in two rows between the raceways. Whereas the carrier pin is cantilevered from the carrier flange, the inner race is cantilevered from the carrier pin remote from the carrier flange, and this insures that the axes about which the planet gears rotate remain parallel to the central axis of the system.

What is claimed is:  
     
         1 . An epicyclic gear system comprising: a sun gear located along a central axis; a ring gear located around the sun gear and sharing the central axis with the sun gear; at least one planet gear located between and engaged with the sun and ring gears for rotation about an offset axis, the planet gear having a raceway that is presented toward the offset axis; and a carrier coupled to the planet gear and including a carrier flange, a carrier pin projecting from the flange into the planet gear, an inner race attached to the carrier pin remote from the carrier flange and also located within the ring gear where it has a raceway presented outwardly away from the offset axis and toward the raceway carried by the ring gear, and rolling elements located in a row between and contacting the raceways on the ring gear and inner race.  
     
     
         2 . A gear system according to  claim 1  wherein the carrier pin is cantilevered from the carrier flange, and the inner race is cantilevered from the carrier pin at a location remote from the carrier flange.  
     
     
         3 . A gear system according to  claim 2  wherein the inner race includes a sleeve which surrounds, but is spaced from the carrier pin, and an end wall connected to the sleeve at one end of the sleeve; wherein the raceway for the inner race is on the sleeve; and wherein the carrier pin is connected to the inner race at the end wall of the inner race.  
     
     
         4 . A gear system according to  claim 3  wherein the end wall and the sleeve are formed integral.  
     
     
         5 . A gear system according to  claim 4  wherein the carrier pin and the end wall of the inner race are formed integral.  
     
     
         6 . A gear system according to  claim 3  wherein the raceway on the planet gear is one of two outer raceways which are located oblique to the offset axis and are inclined in opposite directions; wherein the raceway on the inner race is one of two inner raceways that are oriented oblique to the offset axis and inclined in opposite directions, one of the inner raceways being located within and inclined in the same direction as one of the outer raceways and the other inner raceway being located within and inclined in the same direction as the other outer raceway; and wherein the rolling elements are arranged in two rows between the outer and inner raceways.  
     
     
         7 . A gear system according to  claim 6  wherein the raceways are tapered; wherein the rolling elements are tapered rollers; wherein the sleeve of the inner race has thrust ribs at the large ends of the tapered inner raceways; and wherein one of the thrust ribs fits over the inner race as an initially separate component.  
     
     
         8 . In an epicyclic gear system including a sun gear located along a central axis, a ring gear located around the sun gear and sharing the central axis; planet gears located between and engaged with the sun and ring gears for rotation about offset axes that are located around the central axis; a carrier coupled with the planet gears and including a carrier flange offset axially from the planet gears, carrier pins cantilevered from the carrier flange and projected into the planet gears along the offset axes, there being a separate carrier pin for each planet gear, an inner race cantilevered from each carrier pin remote from the carrier flange and located within the planet gear into which the pin projects, a first inner raceway carried by each inner race and presented outwardly away from the offset axes for that inner race, a first outer raceway carried by the planet gear that is located around the carrier pin and presented inwardly toward the offset axes and toward the first inner raceway on the inner race; and rolling elements located between and contacting the first raceways.  
     
     
         9 . The combination according to  claim 8  and further comprising a second inner raceway carried by the inner race around each carrier pin and presented outwardly away from the offset axes for that carrier pin, a second outer raceway carried by the planet gear that is around the carrier pin and presented inwardly toward the offset axes and the second inner raceway; and wherein the rolling elements are arranged in two rows, with one row being between the first inner and outer raceways and the other row being between the second inner and outer raceways.  
     
     
         10 . The combination according to  claim 9  wherein the raceways are oblique to the offset axes; and wherein the first inner and outer raceways are inclined in the same direction and the second inner and outer raceways are inclined in the same direction, which direction is opposite to the direction of inclination of the first raceways, whereby the rolling elements in the row between the first raceways will transfer thrust loads in one axial direction and the rolling elements in the row between the second raceways will transfer thrust loads in the opposite axial direction.  
     
     
         11 . The combination according to  claim 10  wherein the raceways are tapered and the rolling elements are tapered rollers.  
     
     
         12 . The combination according to  claim 11  wherein the first and second raceways taper inwardly toward each other so that the large ends of the rollers in the row between the first raceways are presented away from the large ends of the rollers in the row between the second raceways.  
     
     
         13 . The combination according to  claim 12  wherein the inner race has thrust ribs at the large ends of the inner raceways; and wherein one of the thrust ribs is a rib ring formed as a separate component that is installed on the inner race after the rollers are placed between the planet gear and the inner race.  
     
     
         14 . The combination according to  claim 10  wherein inner race includes a sleeve on which the inner raceways are located and an end wall at one end of the sleeve; the end wall being attached firmly to the carrier pin remote from the carrier flange with the sleeve surrounding, but being spaced from the carrier pin.  
     
     
         15 . In an epicyclic gear system having a central axis and a planet gear that rotates about an offset axis that is offset radially from the central axis, the improvement comprising: a carrier flange located beyond one end of the planet gear, a carrier pin projecting from the carrier flange into the planet gear such that it is cantilevered from the carrier flange; and a bearing located between the carrier pin and the planet gear for coupling the planet gear to the carrier flange and enabling the planet gear to rotate about the offset axis, the bearing including an inner race which is attached to the carrier pin remote from the carrier flange and includes a sleeve which surrounds the carrier pin, yet is spaced from the pin, the sleeve having a first raceway that is presented outwardly away from the offset axis for the planet gear, the bearing also including a first outer raceway that is carried by the planet gear and is presented inwardly toward the offset axis and the first inner raceway, the bearing further including rolling elements arranged in a row between the first inner and outer raceways.  
     
     
         16 . The combination according to  claim 15  wherein the inner race also includes an end wall extended between the sleeve and the carrier pin and attached firmly to the pin remote from the carrier, whereby the inner race is cantilevered from the carrier pin.  
     
     
         17 . The combination according to  claim 15  wherein the first inner and outer raceways are inclined in the same direction with respect to the offset axis; wherein the inner race has a second inner raceway that is presented outwardly away from the offset axis and is inclined with respect to the offset axis in a direction opposite the inclination of the first raceways, and the bearing also includes a second outer raceway carried by the planet gear and presented inwardly toward the second inner raceway and inclined with respect to the offset axis in the same direction as the second inner raceway; and wherein the rolling elements are organized in first and second rows, the rolling elements of the first row being between the first raceways and the rolling elements of the second row being between the second raceways.  
     
     
         18 . The combination according to  claim 17  wherein the raceways are tapered and the rolling elements are tapered rollers; wherein the inner race has a thrust rib at the large end of the first inner raceway with the rib projecting beyond the first inner raceway, the large ends of the rollers in the first row being against the thrust rib, and the inner race also has a mounting surface at the large end of the second inner raceway with the mounting surface having a diameter no greater than the diameter of the large end of the second inner raceway, and wherein an initially separate rib ring is located around the mounting surface on the inner race and projects outwardly beyond the large end of the second inner raceway, the large ends of the tapered rollers in the second row being against the rib ring.  
     
     
         19 . The combination according to  claim 18  wherein the inner race also includes an end wall extended between the sleeve and the carrier pin and attached firmly to the carrier pin remote from the carrier flange, whereby the inner race is cantilevered from the carrier pin.  
     
     
         20 . The combination according to  claim 19  wherein the end wall and sleeve of the inner race are integral.  
     
     
         21 . In an epicyclic gear system having a central axis and a planet gear offset radially from the central axis where it is located between and engaged with other gears, the improvement comprising: a carrier flange located beyond one end of the planet gear; a carrier pin projecting from the carrier flange into the planet gear, the carrier pin being offset from the central axis and cantilevered from the carrier flange; an inner race attached to the pin remote from the carrier flange such that the inner race is cantilevered from the pin, the inner race having an inner raceway that is presented outwardly away from the carrier pin; an outer raceway carried by the planet gear and presented toward the inner raceway on the inner race; and rolling elements located in a row between and contacting the inner and outer raceways.  
     
     
         22 . The combination according to  claim 21  wherein the inner race includes a sleeve which surrounds the carrier pin and carries the inner raceway, yet is spaced from the pin, and an end wall at one end of the sleeve, with the inner race being attached to the carrier pin at the end wall.