Gear train of an automatic transmission for a vehicle

A gear train of an automatic transmission having first and second planetary gear sets comprising simple planetary gear sets and a third planetary gear set comprising a compound planetary gear set, and a plurality of friction members, wherein:

• the first planetary gear set reduces an engine speed received from an input shaft through a first input path and outputs the reduced speed through a first intermediate output path;
• the second planetary gear set receives the reduced speed through first and second intermediate input paths, and outputs the reduced speed or a reversed speed through a second intermediate output path, the second planetary gear set selectively acting as a fixed element;
• and
• the third planetary gear set selectively receives the engine speed from the input shaft through a second input path, selectively receives input speeds from the first and second planetary gear sets through third and fourth intermediate input paths, and outputs a plurality of changes speeds through a final output path,
• wherein the second planetary gear set comprises:
• a sun gear that forms the first intermediate input path by being fixedly connected to the first intermediate output path of the first planetary gear set;
• a planet carrier that selectively acts as a fixed element and forms the second intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set;
• and
• a ring gear that selectively acts as a fixed element and forms the second intermediate output path.

A gear train of an automatic transmission having first and second planetary gear sets comprising simple planetary gear sets and a third planetary gear set comprising a compound planetary gear set, and a plurality of friction members, wherein:

• the first planetary gear set reduces an engine speed received from an input shaft through a first input path and outputs the reduced speed through a first intermediate output path;
• the second planetary gear set receives the reduced speed through first and second intermediate input paths, and outputs the reduced speed or a reversed speed through a second intermediate output path, the second planetary gear set selectively acting as a fixed element;
• and
• the third planetary gear set selectively receives the engine speed from the input shaft through a second input path, selectively receives input speeds from the first and second planetary gear sets through third and fourth intermediate input paths, and outputs a plurality of changes speeds through a final output path;
• wherein the second planetary gear set comprises:
• a sun gear that forms the first intermediate input path by being fixedly connected to the first intermediate output path of the first planetary gear set;
• a ring gear that selectively acts as a fixed element and forms the second intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set;
• and
• a planet carrier that selectively acts as a fixed element and forms the second intermediate output path.

A gear train of an automatic transmission having first and second planetary gear sets comprising single pinion planetary gear sets, a third planetary gear set comprising a compound planetary gear set sharing a ring gear and a planet carrier, wherein

• the first planetary gear set comprises:
• a sun gear acting as a fixed element;
• a planet carrier that forms a first intermediate output path;
• and
• a ring gear that forms the first input path by being directly connected with an input shaft,
• the second planetary gear set comprises:
• a sun gear that forms a first intermediate input path by being fixedly connected to the first intermediate output path of the first planetary gear set;
• a planet carrier that selectively acts as a fixed element and forms a second intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set;
• and
• a ring gear that selectively acts as a fixed element and forms a second intermediate output path, and
• the third planetary gear set comprises:
• a smaller-diameter sun gear that forms a third intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set;
• a larger-diameter sun gear that forms a fourth intermediate input path by being directly connected to the second intermediate output path of the second planetary gear set;
• a planet carrier that forms the second input path by being variably connected with the input shaft;
• and
• a ring gear that forms the output path by being variably connected with a sun gear.

A gear train of an automatic transmission for a vehicle having a first planetary gear set comprising a single pinion planetary gear set, a second planetary gear set of comprising double pinion planetary gear set, and a third planetary gear set comprising a compound planetary gear set sharing a ring gear and a planet carrier, wherein

• the first planetary gear set comprises:
• a sun gear acting as a fixed element;
• a planet carrier that forms a first intermediate output path;
• and
• a ring gear that forms the first input path by being directly connected with an input shaft,
• the second planetary gear set comprises:
• a sun gear that forms a first intermediate input path by being fixedly connected to the first intermediate output path of the first planetary gear set;
• a ring gear that selectively acts as a fixed element and forms a second intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set;
• a planet carrier that selectively acts as a fixed element and forms a second intermediate output path, and
• the third planetary gear set comprises:
• a smaller-diameter sun gear that forms a third intermediate input path by being variably connected to the first intermediate output path of the first planetary gear set;
• a larger-diameter sun gear that forms a fourth intermediate input path by being directly connected to the second intermediate output path of the second planetary gear set;
• a planet carrier that forms the second input path by being variably connected with the input shaft;
• and
• a ring gear that forms the output path by being variably connected with a sun gear.