Planetary gearing for a geared neutral traction drive

• US 6,358,178 B1
• Filed: 07/07/2000
• Issued: 03/19/2002
• Est. Priority Date: 07/07/2000
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Wittkopp, Scott Henry
• Primary Examiner(s): Estremsky, Sherry
• Assistant Examiner(s): Lewis, Tisha D.
• Application Number:
  US09/611,981
• Time in Patent Office: 620 Days
• Field of Search: 475/216, 475/217, 475/218, 475/207, 475/206, 475/215, 475/219
• US Class Current: 475/207
• CPC Class Codes: F16H 2037/0886 with switching means, e.g. to change ranges
• CPC Class Codes: F16H 37/084 at least one power path being a continuously variable transmission, i.e. CVT
• CPC Class Codes: F16H 37/086 CVT using two coaxial friction members cooperating with at least one intermediate friction member

Abstract

A powertrain having an engine and a continuously variable transmission provides a continuously variable drive ratio between the engine and the transmission output. The transmission includes a continuously variable unit (CVU) and a planetary gear arrangement. The CVU is of the traction type. The planetary gear arrangement has a compound planetary gear set, two simple planetary gear sets, and two torque transmitting mechanisms. The compound gear set is disposed adjacent the CVU and has members connected with the input and the output of the CVU. The two simple planetary gear sets are disposed axially between the compound planetary gear set and transmission output shaft. The sun gear member of the compound planetary gear set is rotatably supported on a single shaft that passes axially therethrough and transmits power from the engine to the carrier assembly member of the compound planetary gear set and one input member of the CVU. The sun gear members of the simple planetary gear sets are interconnected and rotatably supported on a single shaft that passes axially therethrough and delivers power from the ring gear member of the compound planetary gear set and the carrier assembly member of one simple planetary gear set to one of the torque transmitting mechanisms. The torque transmitting mechanisms are supplied with pressurized fluid through a common support element.

Claims

1. A continuously variable transmission comprising:

an input member;

an output member;

a continuously variable unit positioned coaxial with and connected to said input member;

a compound planetary gear set, positioned axially adjacent said continuously variable unit, including a sun gear member, a carrier assembly member, and a ring gear member, a shaft portion of said input member passing coaxially through and rotatably supporting said sun gear member, said shaft portion being the sole rotating member passing through said sun gear member and being drivingly connected with said carrier assembly member;

a first simple planetary gear set, positioned axially adjacent said compound planetary gear set, including a sun gear member, a ring gear member, and a carrier assembly member;

a second simple planetary gear set, positioned coaxially between said first simple planetary gear set and said output member, including a sun gear member, a ring gear member, and a carrier assembly member, said sun gear member being drivingly connected with said sun gear member of said first simple planetary gear set; and

an intermediate shaft passing coaxially through and rotatably supporting both said sun gear members of said first and second simple planetary gear sets, said intermediate shaft being the sole rotating member passing through said sun gears and being continuously drivingly connected with said ring gear member of said compound gear set and said carrier assembly member of said first simple planetary gear set and transmitting rotation therefrom to a selectively engageable torque transmitting mechanism connectable between said intermediate shaft and said output member.

2. A continuously variable transmission comprising:

input means including input shaft means for transmitting power to said continuously variable transmission;

output means including output shaft means for transmitting power from said continuously variable transmission;

a continuously variable unit having axially spaced input members and centrally disposed output members, said input shaft means passing concentrically through said continuously variable unit and being drivingly connected to a first of said input members;

a compound planetary gear set disposed adjacent said continuously variable unit and having a first sun gear member drivingly connected with said output members of said continuously variable unit, a first carrier assembly member drivingly connected with a second of said input members, and a ring gear member, said input shaft means having a portion thereof passing concentrically through said first sun gear member and being drivingly connected with said first carrier member and being the only rotatable member passing through said first sun gear;

a first simple planetary gear set disposed adjacent said compound planetary gear set and having a second sun gear member, a second carrier assembly member continuously drivingly connected with said first ring gear member, and a second ring gear member drivingly connected with said first carrier assembly member;

a second simple planetary gear set disposed between said first simple planetary gear set and said output means and having a third sun gear member continuously drivingly connected with said second sun gear, a third ring gear member continuously drivingly connected with said output means, and a third carrier assembly member; and

an intermediate shaft means for transmitting power from said first ring gear member and said second carrier assembly member to a first torque transmitting mechanism that is selectively connectable with said output means, said intermediate shaft means passing concentrically through said second and third sun gear members and being the sole rotatable member passing therethrough.

3. The continuously variable transmission defined in claim 2 further comprising:

a second torque transmitting mechanism selectively connectable between said third carrier assembly member and a stationary portion of said transmission, said second torque transmitting means being engaged to establish a reverse range and a first forward range in said transmission and said continuously variable unit being controllable to provide a variable between an overdrive ratio to an underdrive ratio to establish the reverse range, a geared neutral condition, and the first forward range.

4. The continuously variable transmission defined in claim 3 further comprising:

said first torque transmitting mechanism being selectively engaged to provide a second forward range and said continuously variable unit being controlled from an underdrive ratio to an overdrive ratio during said second forward range.

5. The continuously variable transmission defined in claim 4 further comprising:

said second and first torque transmitting mechanisms being synchronously interchanged when said continuously variable unit is at a maximum underdrive ratio.

6. The continuously variable transmission defined in claim 5 further comprising:

closure means formed on said housing;

fluid passage means formed in said closure means for supplying fluid to and exhausting fluid from said first torque transmitting mechanism and said second torque transmitting mechanism.