Electrically variable transmission having three planetary gear sets and two fixed interconnections and a stationary interconnection
View Patent ↗The electrically variable transmission family of the present invention provides low-content, low-cost electrically variable transmission mechanisms including first, second and third differential gear sets, a battery, two electric machines serving interchangeably as motors or generators, and six selectable torque-transfer devices, which may include a dog clutch. The selectable torque transfer devices are engaged singly or combinations of two to yield an EVT with a continuously variable range of speeds (including reverse) and up to four mechanically fixed forward speed ratios. The torque transfer devices and the first and second motor/generators are operable to provide five operating modes in the electrically variable transmission, including battery reverse mode, EVT reverse mode, reverse and forward launch modes, continuously variable transmission range mode, and fixed ratio mode.
1. An electrically variable transmission comprising:
an input member to receive power from an engine;
an output member;
first and second motor/generators;
first, second, and third differential gear sets each having first, second, and third members;
said input member being continuously connected with at least one member of said gear sets, and said output member being continuously connected with another member of said gear sets;
a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set and with said first member of said third gear set;
a second interconnecting member continuously grounding one of said members of said first gear set;
said first motor/generator being selectively alternately connectable with members of said second gear set;
said second motor/generator being continuously connected with a member of said third gear set; and
first, second, third, fourth, fifth, and sixth torque-transfer devices for selectively interconnecting said members of said first, second, or third gear sets with a stationary member, one of said first and second motor/generators, or with other members of said planetary gear sets, said first, second, third, fourth, fifth, and sixth torque-transfer devices being engageable to provide said electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios between said input member and said output member.
2. The electrically variable transmission of claim 1 , wherein said first, second, and third differential gear sets are planetary gear sets, and said first torque-transfer device selectively connects a member of said second planetary gear set with a member of said third planetary gear set.
3. The electrically variable transmission of claim 2 , wherein said second torque-transfer device selectively connects a member of said second planetary gear set with a member of said third planetary gear set, the pair of members connected by said second torque-transfer device being different from the pair of members connected by said first-torque transfer device.
4. The electrically variable transmission of claim 3 , wherein said third torque-transfer device selectively connects a member of said third planetary gear set with said stationary member.
5. The electrically variable transmission of claim 4 , wherein said fourth torque-transfer device is connected in parallel with one of said motor/generators for selectively preventing rotation thereof.
6. The electrically variable transmission of claim 5 , wherein said fifth torque-transfer device connected in parallel with the other of said motor/generators for selectively preventing rotation thereof.
7. The electrically variable transmission of claim 5 , wherein said sixth torque-transfer device is a dog clutch operable for selecting between one position for connecting said first motor/generator to a member of said second planetary gear set, and another position for connecting said first motor/generator directly to said output member.
8. An electrically variable transmission comprising:
an input member to receive power from an engine;
an output member;
first and second motor/generators;
first, second and third differential gear sets each having first, second, and third members;
said input member being continuously connected with at least one member of said gear sets, and said output member being continuously connected with another member of said gear sets;
a first interconnecting member continuously connecting said first member of said first gear set with said first member of said second gear set and with said first member of said third gear set;
a second interconnecting member continuously grounding one of said members of said first gear set;
said first motor/generator being selectively alternately connectable with members of said second gear set;
said second motor/generator being continuously connected with a member of said third gear set;
a first torque-transfer device selectively connecting a member of said second gear set with another member of said third gear set;
a second torque-transfer device selectively connecting a member of said second gear set with another member of said third gear set which is different from said member selectively connected with said first torque-transfer device;
a third torque-transfer device selectively grounding a member of said third gear set;
a fourth torque-transfer device connected in parallel with one of said first and second motor/generators for selectively preventing rotation thereof;
a fifth torque-transfer device connected in parallel with the other of said first and second motor/generators for selectively preventing rotation thereof; and
a sixth torque-transfer device selectively connecting said first motor/generator with a member of said second gear set;
wherein said first, second, third, fourth, fifth, and sixth torque-transfer devices are selectively engageable to provide said electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios.
9. The electrically variable transmission of claim 8 , wherein said first, second, and third differential gear sets are planetary gear sets.
10. The electrically variable transmission of claim 9 , wherein said sixth torque-transfer device is operable for selecting between one position for connecting said first motor/generator with said member of said second planetary gear set, and another position for connecting said first motor/generator directly with said output member.
11. The electrically variable transmission of claim 10 , wherein said sixth torque-transfer device is selected from the group of a dog clutch, a two-way clutch, and a pair of rotary clutches.
12. The electrically variable transmission of claim 11 , further comprising offset gearing, wherein said sixth torque-transfer device is said dog clutch, and wherein said dog clutch is operatively connected to said first motor/generator through said offset gearing.
13. An electrically variable transmission comprising:
an input member to receive power from an engine;
an output member;
first and second motor/generators;
first, second, and third planetary gear sets each having a ring gear member, a sun gear member, and a carrier member;
said input member being continuously connected with said ring gear member of said first planetary gear set, and said output member being continuously connected with said carrier member of said second planetary gear set;
a first interconnecting member continuously connecting said carrier member of said first gear set with said ring gear member of said second gear set and with said carrier member of said third gear set;
a second interconnecting member continuously grounding said sun gear member of said first gear set;
said first motor/generator being selectively alternately connectable with said sun gear member of said second gear set;
said second motor/generator being continuously connected with said sun gear member of said third gear set;
a first torque-transfer device selectively connecting said sun gear member of said second planetary gear set with said ring gear member of said third planetary gear set;
a second torque-transfer device selectively connecting said carrier member of said second planetary gear set with said ring gear member of said third gear set;
a third torque-transfer device selectively grounding said carrier member of said third gear set;
a fourth torque-transfer device connected in parallel with said first second motor/generator for selectively preventing rotation thereof,
a fifth torque-transfer device connected in parallel with said second motor/generator for selectively preventing rotation thereof, and
a sixth torque-transfer device selectively connecting said first motor/generator with said sun gear member of said second gear set;
wherein said first, second, third, fourth, fifth, and sixth torque-transfer devices are selectively engageable to provide said electrically variable transmission with a continuously variable range of speed ratios and four fixed forward speed ratios.
14. The electrically variable transmission of claim 13 , wherein said sixth torque-transfer device is operable for selecting between one position for connecting said first motor/generator with said sun member of said second planetary gear set, and another position for connecting said first motor/generator directly with said output member.
15. The electrically variable transmission of claim 14 , wherein said sixth torque-transfer device is selected from the group of a dog clutch, a two-way clutch, and a pair of rotary clutches.