Multi-speed planetary power transmission
A power transmission for use in a powertrain has an input shaft, an output shaft, an input planetary gearset, and an output planetary gearset. The planetary gearsets are controlled through the selective engagement of seven torque-transmitting mechanisms, three of which are rotating-type torque-transmitting mechanisms and four of which are stationary-type torque-transmitting mechanisms. By selective engagement of the torque-transmitting mechanisms in combinations of three, the input planetary gearset and the output planetary gearset are combined to establish eight forward speed ratios between the input shaft and the output shaft.
1. A multi-speed power transmission comprising:
an input shaft;
an output shaft;
an input planetary gearset having first, second, and third members, said second member being continuously connected with said input shaft;
an output planetary gearset having first, second, third, fourth, and fifth members;
a first selectively engageable torque-transmitting mechanism interconnecting said third member of said input planetary gearset with said first member of said output planetary gearset;
a second torque-transmitting mechanism selectively interconnecting said third member of said first planetary gearset with said second member of said output planetary gearset;
a third torque-transmitting mechanism selectively engageable between said input shaft and said fifth member of said output planetary gearset;
a fourth torque-transmitting mechanism selectively engageable to connect said second member of said output planetary gearset with a stationary housing;
a fifth torque-transmitting mechanism selectively engageable to connect said fifth member of said output planetary gearset with said stationary housing;
a sixth torque-transmitting mechanism selectively engageable to connect said fourth member of said output planetary gearset with said housing;
a seventh torque-transmitting mechanism selectively engageable to connect said first member of said input planetary gearset with said housing;
said third member of said output planetary gearset being continuously interconnected with said output shaft;
said torque-transmitting mechanisms being selectively engaged in combinations of three to establish at least eight forward speed ratios and one reverse speed ratio in said planetary transmission between said input shaft and said output shaft.
2. The multi-speed transmission defined in claim 1 , further wherein:
said seventh torque-transmitting mechanism is effective when engaged to establish a reduced speed drive between said transmission input shaft and said third member of said first planetary gearset.
3. The multi-speed transmission defined in claim 1 , further wherein:
said second, fifth, and seventh torque-transmitting mechanisms are selectively engaged to provide the reverse speed ratio, said first, fifth, and seventh torque-transmitting mechanisms are selectively engaged to provide the first forward speed ratio, said first, sixth, and seventh torque-transmitting mechanisms are engaged to provide the second forward speed ratio, said first, fourth, and seventh torque-transmitting mechanisms are selectively engaged to provide the third forward speed ratio, said first, second, and seventh torque-transmitting mechanisms are selectively engaged to provide the fourth forward speed ratio, said first, third, and seventh torque-transmitting mechanisms are selectively engaged to provide the fifth forward speed ratio, said first, second, and third torque-transmitting mechanisms are selectively engaged to provide the sixth forward speed ratio, said second, third, and seventh torque-transmitting mechanisms are selectively engaged to provide the seventh forward speed ratio, and said third, fourth, and seventh torque-transmitting mechanisms are selectively engaged to provide the eighth forward speed ratio.
4. The multi speed transmission defined in claim 1 further wherein:
said torque transmitting mechanisms are engaged in combinations of three to provide nine forward speed ratios.
5. The multi-speed transmission defined in claim 4 , further wherein:
said second, fifth, and seventh torque-transmitting mechanisms are selectively engaged to provide the reverse speed ratio;
said first, fifth, and seventh torque-transmitting mechanisms are selectively engaged to provide the first forward speed ratio;
said first, sixth, and seventh torque-transmitting mechanisms are engaged to provide the second forward speed ratio;
said first, fourth, and seventh torque-transmitting mechanisms are selectively engaged to provide the third forward speed ratio;
said first, second, and seventh torque-transmitting mechanisms are selectively engaged to provide the fourth forward speed ratio;
said first, third, and seventh torque-transmitting mechanisms are selectively engaged to provide the fifth forward speed ratio;
said first, second, and third torque-transmitting mechanisms are selectively engaged to provide the sixth forward speed ratio;
said second, third, and seventh torque-transmitting mechanisms are selectively engaged to provide the seventh forward speed ratio;
said third, fourth, and seventh torque-transmitting mechanisms are selectively engaged to provide the eighth forward speed ratio; and
said third, sixth, and seventh torque transmitting mechanisms are selectively engaged to provide the ninth forward speed ratio.