Patent ID: 7416507
Filing Date: 2008-08-26
Classification: F16H

Abstract:
1. A multi-speed transmission comprising: a transmission casing having a first end wall, a second end wall, and a housing portion interconnecting the first end wall and the second end wall; wherein the end walls and the housing portion define a cavity; an input member; an output member; first, second, third and fourth planetary gear sets within the cavity, each planetary gear set having a ring gear member, a sun gear member, and a carrier member rotatably supporting pinion gears intermeshing with both the ring gear member and the sun gear member; wherein the transmission casing and the planetary gear sets define six zones within the cavity, including a first zone extending axially from the first end wall to the first planetary gear set and extending radially to an outer periphery of the planetary gear sets; a second zone extending axially from the first planetary gear set to the third planetary gear set and extending radially to the outer periphery of the planetary gear sets, a third zone extending axially from the third planetary gear set to the second planetary gear set and extending radially to the outer periphery of the planetary gear sets, a fourth zone extending axially from the second planetary gear set to the fourth planetary gear set and extending radially to the outer periphery of the planetary gear sets, a fifth zone extending axially from the fourth planetary gear set to the second end wall and extending radially to the outer periphery of the planetary gear sets, and a sixth zone bordering the first, second, third, fourth and fifth zones and extending radially outward to the housing portion and axially between the first and second walls; wherein the ring gear member of the first planetary gear set is continuously connected for common rotation with the sun gear member of the second planetary gear set; wherein the ring gear member of the second planetary gear set is continuously connected for common rotation with the carrier member of the third planetary gear set; wherein the ring gear member of the third planetary gear set is continuously connected for common rotation with the carrier member of the fourth planetary gear set; wherein the sun gear member of the third planetary gear set is continuously connected for common rotation with the sun gear member of the fourth planetary gear set; wherein the sun gear member of the first planetary gear set is grounded to the transmission casing; a first torque-transmitting mechanism selectively engagable to ground the ring gear member of the fourth planetary gear set to the transmission casing; a second torque-transmitting mechanism selectively engagable to connect the ring gear member of the first planetary gear set for common rotation with the sun gear member of the third planetary gear set; a third torque-transmitting mechanism selectively engagable to connect the carrier member of the first planetary gear set for common rotation with the carrier member of the second planetary gear set; a fourth torque-transmitting mechanism selectively engagable to connect the carrier member of the first planetary gear set for common rotation with the sun gear member of the third planetary gear set; a fifth torque-transmitting mechanism selectively engagable to connect the carrier member of the second planetary gear set for common rotation with the ring gear member of the fourth planetary gear set; wherein the first torque-transmitting mechanism is located in one of the first, fifth and sixth zones; wherein the second torque-transmitting mechanism is located in one of the first, second and sixth zones; wherein the third torque-transmitting mechanism is located in one of the first and sixth zones; wherein the fourth torque-transmitting mechanism is located in one of the first, second and fifth zones; wherein the sixth torque-transmitting mechanism is located in one of the first, fourth, fifth and sixth zones; and wherein the torque-transmitting mechanisms are selectively engagable in different combinations to achieve eight forward speed ratios and a reverse speed ratio between the input member and the output member.