Patent ID: 7416509
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 second planetary gear set and extending radially to an outer periphery of the planetary gear sets; a second zone extending axially from the second 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 fourth planetary gear set and extending radially to the outer periphery of the planetary gear sets, a fourth zone extending axially from the fourth planetary gear set to the first planetary gear set and extending radially to the outer periphery of the planetary gear sets, a fifth zone extending axially from the first 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 connect the ring gear member of the fourth planetary gear set to the sun gear member of the first planetary gear set, thereby grounding the ring gear member of the fourth planetary gear set to the transmission casing; a second torque-transmitting mechanism selectively engagable to connect the sun gear member of the second planetary gear set, and thereby 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 fourth and fifth zones; wherein the second torque-transmitting mechanism is located in one of the first and second zones; wherein the third torque-transmitting mechanism is located in one of the first, fourth and sixth zones; wherein the fourth torque-transmitting mechanism is located in one of the first, second and sixth zones; and wherein the fifth torque-transmitting mechanism is located in one of the first, third, fourth 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.