Dual input planetary final drive
The present invention provides a final drive assembly having a differential driven by a planetary gear set having two inputs. The ring gear of the planetary gear set is stationary. One of the inputs is coupled to and drives the planet gear carrier which, in turn, is coupled to and drives the cage of the differential. The other input is coupled to and drives the sun gear of the planetary gear set. Incorporated into a suitable powertrain, for example, one having a dual clutch transmission (DCT) with two outputs, one associated with higher ratio (lower speed) gears and another associated with lower ratio (higher speed) gears, the sun gear carries power in the lower speed gears and provides torque multiplication. In the higher speed gears, power is carried by the planet gear carrier directly to the differential cage, bypassing the speed reduction, torque multiplication and gear mesh losses of the planetary gear set.
1. A final drive assembly for a motor vehicle comprising, in combination,
a first input for receiving lower speed range power from a transmission,
a second input for receiving higher speed range power from a transmission,
a planetary gear assembly having a grounded ring gear, a sun gear coupled to said first input, a planet gear carrier coupled to said second input and having a plurality of planet gears,
a differential having an outer member coupled to said planet carrier and a pair of differentially rotatable outputs adapted to drive a respective pair of axles,
a transmission having a first output carrying lower speed ranges coupled to said first input of said final drive assembly and a second output carrying higher speed ranges coupled to said second input of said final drive assembly, and
a first gear set operably disposed between said first output of said transmission and said first input of said final drive assembly and a second gear set operably disposed between said second output of said transmission and said second input of said final drive assembly.
2. The final drive assembly of claim 1 wherein said differential is a cage differential, said outer member is a cage and further including a pair of opposed idler gears and a pair of drive gears meshing with both idler gears and coupled to a respective one of a pair of axles.
3. The final drive assembly of claim 1 wherein said differential is a compound planetary gear assembly, said outer member is a ring gear and further including a planet gear carrier coupled to one of a pair of axles and a sun gear coupled to another of a pair of axles.
4. The final drive assembly of claim 1 wherein said transmission is a dual clutch transmission.
5. The final drive assembly of claim 1 further including a drive tube between said first input and said sun gear and wherein an axle extends through said drive tube.
6. A final drive assembly for a motor vehicle comprising, in combination,
a first input member adapted to receive lower speed drive torque from a transmission,
a second input member adapted to receive higher speed drive torque from said transmission,
a planetary gear set having a stationary ring gear, a sun gear coupled to said first input member, and a planet gear carrier coupled to said second input member,
a differential having an input coupled to said planet gear carrier and means for providing a pair of differential outputs coupled to a respective pair of axles,
a transmission having a first output carrying lower speed ranges coupled to said first input member and a second output carrying higher speed ranges coupled to said second input member, and
a first gear set operably disposed between said first output of said transmission and said first input member and a second gear set operably disposed between said second output of said transmission and said second input member.
7. The final drive assembly of claim 6 wherein said differential is a cage differential, said input is a cage and said means includes a pair of opposed idler gears and a pair of drive gears meshing with both idler gears and coupled to a respective one of a pair of axles.
8. The final drive assembly of claim 6 wherein said differential is a compound planetary gear assembly, said input is a ring gear and said means is a planet gear carrier coupled to one of a pair of axles and a sun gear coupled to another of a pair of axles.
9. The final drive assembly of claim 6 wherein said transmission is a dual clutch transmission.
10. The final drive assembly of claim 6 wherein said first input member is a drive tube coupled to said sun gear and wherein an axle extends through said drive tube.
11. A drive assembly for a motor vehicle comprising, in combination,
a first input for receiving drive torque associated with a first set of transmission gear ratios,
a second input for receiving drive torque associated with a second set of transmission gear ratios,
a planetary gear set having a stationary ring gear, a sun gear coupled to said first input and a planet gear carrier coupled to said second input, and a differential having an outer member coupled to said planet carrier and means for providing a pair of differentiated outputs,
a transmission having a first output associated with the first set of transmission gear ratios coupled to said first input and a second output associated with the second set of transmission gear ratios coupled to said second input, and
a first gear set operably disposed between said first output of said transmission and said first input member and a second gear set operably disposed between said second output of said transmission and said second input member.
12. The drive assembly of claim 11 further including a pair of axles driven by said pair of differentiated outputs.
13. The drive assembly of claim 11 wherein said differential is a cage differential, said outer member is a cage and said means includes a pair of opposed idler gears and a pair of drive gears meshing with both idler gears.
14. The drive assembly of claim 11 wherein said differential is a compound planetary gear assembly, said outer member is a ring gear and said means is a planet gear carrier providing one of said outputs and a sun gear providing another of said pair of outputs.
15. The drive assembly of claim 11 wherein said transmission is a dual clutch transmission.