Two-speed transmission for electric vehicle

Abstract

A two-speed transmission for a vehicle is provided including a planetary gear set selectively coupling an input shaft and an output shaft. The planetary gear set is configured to provide two forward gear ratios and neutral. The planetary gear set includes at least one sun gear, at least one pinion in meshing engagement with the sun gear, at least one ring gear meshingly engaged with the pinion, and a carrier. The carrier supports the pinion and is connected to the output shaft such that rotation of the carrier drives the output shaft. The two-speed transmission also includes one or more elements that rotatably couple different combinations of the sun gear, the pinion, the ring gear, the input shaft, and the carrier with one another or a ground. Such elements may include combinations of clutches, brakes, band brakes, dog clutches, and mechanical diodes.

What is claimed is: 
     
         1 . A two-speed transmission that transfers torque from a motor to a final drive unit, comprising:
 an input shaft having a first end that connects with the motor and a second end opposite said first end;   an output shaft that connects with the final drive unit;   a planetary gear set selectively coupling said input shaft and said output shaft;   said planetary gear set including a sun gear connected to said input shaft;   said planetary gear set including at least one double step pinion having a first gear and a second gear rotatably fixed with said first gear;   said first gear having a first outer diameter and said second gear having a second outer diameter that is less than said first outer diameter;   said first gear of said at least one double step pinion being meshingly engaged with said sun gear and disposed radially outwardly of said sun gear;   said planetary gear set including a ring gear meshingly engaged with said second gear of said at least one double step pinion and circumscribing said second gear of said at least one double step pinion;   said planetary gear set including a carrier connected to said output shaft and supporting said at least one double step pinion;   a multi-plate wet clutch assembly including a brake fixed to a ground and a clutch connected to said carrier;   said brake being connected to said ring gear and providing a first gear ratio by resisting rotation of said ring gear with respect to said ground when said brake is engaged; and   said clutch being connected to said input shaft and providing a second gear ratio by rotatably coupling said input shaft and said carrier when said clutch is engaged.   
     
     
         2 . The two-speed transmission of  claim 1  wherein said multi-plate wet clutch assembly provides neutral in response to said brake permitting free rotation of said ring gear and said clutch permitting free rotation of said input shaft. 
     
     
         3 . The two-speed transmission of  claim 1  further comprising a dog clutch connected to said brake and including a plurality of teeth that interlockingly engage said ring gear when said dog clutch is actuated to selectively couple said ring gear and said brake. 
     
     
         4 . The two-speed transmission of  claim 3  wherein said brake includes a brake friction plate connected to said dog clutch where said dog clutch selectively engages said ring gear and said brake selectively engages said brake friction plate to resist rotation of said ring gear with respect to said ground when said first gear ratio is selected. 
     
     
         5 . The two-speed transmission of  claim 1  wherein said clutch includes a clutch friction plate connected to said input shaft between said first end of said input shaft and said sun gear of said planetary gear set where said clutch selectively engages said clutch friction plate to rotatably couple said sun gear and said carrier when said second gear ratio is selected. 
     
     
         6 . The two-speed transmission of  claim 1  further comprising an idler gear disposed between said first gear of said at least one double step pinion and said sun gear. 
     
     
         7 . The two-speed transmission of  claim 1  further comprising an idler gear disposed between said second gear of said at least one double step pinion and said ring gear. 
     
     
         8 . The two-speed transmission of  claim 1  wherein said brake is a band brake fixed to said ground that includes a brake drum connected to said ring gear where said band brake selectively engages said brake drum to resist rotation of said ring gear with respect to said ground when said first gear ratio is selected. 
     
     
         9 . The two-speed transmission of  claim 1  further comprising a mechanical diode connected to said ring gear that selectively couples said ring gear and said brake when said first gear ratio is selected. 
     
     
         10 . The two-speed transmission of  claim 1  further comprising a dog clutch connected to said brake and including a plurality of teeth that interlockingly engage said ground when said dog clutch is actuated to selectively couple said ground and said brake. 
     
     
         11 . A two-speed transmission comprising:
 an input shaft having a first end and a second end opposite said first end;   an output shaft that is spaced from said input shaft;   a planetary gear set selectively coupling said input shaft and said output shaft;   said planetary gear set including a sun gear connected to said input shaft;   said planetary gear set including at least one single pinion gear;   said at least one single pinion gear being meshingly engaged with said sun gear and disposed radially outwardly of said sun gear;   said planetary gear set including a ring gear meshingly engaged with said at least one single pinion gear and circumscribing said at least one single pinion gear;   said planetary gear set including a carrier connected to said output shaft and supporting said at least one single pinion gear;   a brake connected to a ground and to said ring gear;   said brake providing a first gear ratio by resisting rotation of said ring gear with respect to said ground when said brake is engaged;   a clutch connected to said carrier and to said input shaft between said first end of said input shaft and said sun gear; and   said clutch providing a second gear ratio by rotatably coupling said sun gear and said carrier when said clutch is engaged.   
     
     
         12 . The two-speed transmission of  claim 11  wherein said brake and said clutch provide neutral in response to said brake permitting free rotation of said ring gear and said clutch permitting free rotation of said input shaft. 
     
     
         13 . The two-speed transmission of  claim 11  further comprising an idler gear disposed between said at least one single pinion gear and said sun gear. 
     
     
         14 . The two-speed transmission of  claim 11  further comprising an idler gear disposed between said at least one single pinion gear and said ring gear. 
     
     
         15 . A two-speed transmission that transfers torque from a motor to a final drive unit, comprising:
 an input shaft having a first end that connects with the motor and a second end opposite said first end;   an output shaft that connects with the final drive unit;   a planetary gear set selectively coupling said input shaft and said output shaft;   said planetary gear set including a sun gear connected to said input shaft;   said planetary gear set including a first gear and a second gear;   said first gear having a first outer diameter and said second gear having a second outer diameter that is less than said first outer diameter;   said first gear of said planetary gear set disposed in meshing engagement with said sun gear and disposed radially outwardly of said sun gear;   said planetary gear set including a first ring gear disposed in meshing engagement with said first gear of said planetary gear set that circumscribes said first gear of said planetary gear set;   said planetary gear set including a second ring gear disposed in meshing engagement with said second gear of said planetary gear set that circumscribes said second gear of said planetary gear set;   said planetary gear set including a carrier connected to said output shaft that supports said first and second gears;   a first mechanical diode connected to said first ring gear providing selective engagement of said first ring gear;   a second mechanical diode connected to said second ring gear providing selective engagement of said second ring gear;   a multi-plate wet clutch assembly including a first brake connected to a ground and said first mechanical diode and a second brake connected to said ground and said second mechanical diode;   said multi-plate wet clutch assembly providing a first gear ratio in response to engagement of said second brake and said second mechanical diode such that said second brake resists rotation of said second ring gear with respect to said ground; and   said multi-plate wet clutch assembly providing a second gear ratio in response to engagement of said first brake and said first mechanical diode such that said first brake resists rotation of said first ring gear with respect to said ground.   
     
     
         16 . The two-speed transmission of  claim 15  wherein said multi-plate wet clutch assembly provides neutral in response to said first brake permitting free rotation of said first ring gear and said second brake permitting free rotation of said second ring gear. 
     
     
         17 . The two-speed transmission of  claim 15  wherein said first gear and said second gear of said planetary gear set are defined by a double step pinion and rotate together as part of said double step pinion. 
     
     
         18 . The two-speed transmission of  claim 15  further comprising an idler gear disposed between said first gear of said at least one double step pinion and said sun gear. 
     
     
         19 . The two-speed transmission of  claim 15  further comprising an idler gear disposed between said first gear of said at least one double step pinion and said first ring gear. 
     
     
         20 . The two-speed transmission of  claim 15  further comprising an idler gear disposed between said second gear of said at least one double step pinion and said second ring gear. 
     
     
         21 . The two-speed transmission of  claim 15  wherein said first brake includes a first brake friction plate connected to said first mechanical diode and said second brake including a second brake friction plate connected to said second mechanical diode where said second mechanical diode is engaged and said second brake engages said second friction plate when said first gear ratio is selected and where said first mechanical diode is engaged and said first brake engages said first friction plate when said second gear ratio is selected. 
     
     
         22 . A two-speed transmission of  claim 15  wherein said planetary gear set includes a first sun gear connected to said input shaft between said first end of said input shaft and said second end of said input shaft and a second sun gear connected to said input shaft between said first sun gear and said second end of said input shaft. 
     
     
         23 . A two-speed transmission of  claim 22  wherein said first gear is a first pinion gear that is disposed in meshing engagement with said first sun gear and wherein said second gear is a second pinion gear that is disposed in meshing engagement with said second sun gear. 
     
     
         24 . A two-speed transmission of  claim 22  wherein said first pinion gear has a first outer diameter and said second pinion gear has a second outer diameter that is less than said first outer diameter, said first ring gear being meshingly engaged with said first pinion gear and having a first inner diameter that circumscribes said first pinion gear and said first sun gear, said second ring gear being meshingly engaged with said second pinion gear and having a second inner diameter that circumscribes said second pinion gear and said second sun gear, said second inner diameter of said second ring gear being equal to said first inner diameter of said first ring gear and said first ring gear being co-axially aligned with said second ring gear. 
     
     
         25 . The two-speed transmission of  claim 23  further comprising an idler gear disposed between said first pinion gear and said first sun gear. 
     
     
         26 . The two-speed transmission of  claim 23  further comprising an idler gear disposed between said second pinion gear and said second sun gear. 
     
     
         27 . The two-speed transmission of  claim 23  further comprising an idler gear disposed between said first pinion gear and said first ring gear. 
     
     
         28 . The two-speed transmission of  claim 23  further comprising an idler gear disposed between said second pinion gear and said second ring gear. 
     
     
         29 . A transmission comprising:
 an input shaft having a first end and a second end opposite said first end;   an output shaft that is spaced from said input shaft;   a planetary gear set selectively coupling said input shaft and said output shaft;   said planetary gear set including a sun gear connected to said input shaft;   said planetary gear set including at least one double step pinion having a first gear and a second gear rotatably fixed with said first gear;   said first gear having a first outer diameter and said second gear having a second outer diameter that is less than said first outer diameter;   said first gear of said at least one double step pinion being meshingly engaged with said sun gear;   said planetary gear set including a ring gear meshingly engaged with said second gear of said at least one double step pinion and circumscribing said second gear of said at least one double step pinion;   said planetary gear set including a carrier connected to said output shaft and supporting said at least one double step pinion;   a multi-plate wet clutch assembly including a brake fixed to a ground and a clutch rotatably coupled with said ring gear; and   said brake being connected to said ring gear and providing a first gear ratio by resisting rotation of said ring gear with respect to said ground when said brake is engaged.   
     
     
         30 . The transmission of  claim 29  wherein said clutch includes a clutch friction plate that is connected to said input shaft between said first end of said input shaft and said sun gear, said clutch providing a second gear ratio by selectively engaging said clutch friction plate to rotatably couple said input shaft and said ring gear. 
     
     
         31 . The transmission of  claim 30  wherein said multi-plate wet clutch assembly provides neutral in response to said brake permitting free rotation of said ring gear with respect to said ground and said clutch permitting free rotation of said ring gear with respect to said input shaft. 
     
     
         32 . The transmission of  claim 30  further comprising a dog clutch connected to said brake presenting a plurality of teeth that interlockingly engage said ring gear when said dog clutch is actuated to selectively couple said ring gear and said brake. 
     
     
         33 . The transmission of  claim 29  further comprising an idler gear disposed between said first gear of said at least one double step pinion and said sun gear. 
     
     
         34 . The transmission of  claim 29  further comprising an idler gear disposed between said second gear of said at least one double step pinion and said ring gear. 
     
     
         35 . The transmission of  claim 29  wherein said clutch includes a clutch friction plate connected to said carrier of said planetary gear set, said clutch providing a second gear ratio by selectively engaging said clutch friction plate to rotatably couple said carrier and said ring gear. 
     
     
         36 . The two-speed transmission of  claim 35  wherein said multi-plate wet clutch assembly provides neutral in response to said brake permitting free rotation of said ring gear with respect to said ground and said clutch permitting free rotation of said carrier with respect to said ring gear.