# US 8,739,644 B2 · Eight speed dual clutch transmission > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,644 B2 - Document ID: US8739644B2 - Status: Granted - Kind: B2 - Application number: 13/551,265 - Filed: 2012-07-17 - Published: 2013-02-07 - Granted: 2014-06-03 - Earliest claimed: 2011-08-04 - Assignees: GM Global Technology Operations LLC - Applicants: Tejinder Singh; Patrick S. Portell - Inventors: Tejinder Singh; Patrick S. Portell - Web page: https://patentgrep.com/patent/US8739644B2 ## CPC - F16H 3/006: {power being selectively transmitted by parallel flow paths, e.g. dual clutch transmissions} - F16H 2003/0931: {each countershaft having an output gear meshing with a single common gear on the output shaft} - F16H 2200/006: the gear ratios comprising eight forward speeds - Y10T 74/19228: Multiple concentric clutch shafts - F16H: GEARING - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A transmission is connectable to an input member and includes an output transfer gear, first and second shaft members, first, second and third countershaft members, a plurality of co-planar gear sets, and a plurality of torque transmitting devices. The torque transmitting devices include a plurality of gears, synchronizer assemblies and a dual clutch assembly. The transmission is operable to provide at least one reverse speed ratio and a plurality of forward speed ratios between the input member and the output member. ## Claims ### Claim 1 A transmission comprising: a transmission housing; a dual clutch assembly having a first clutch, second clutch and a clutch housing connectable to an engine output member, wherein the clutch housing is rotationally supported within the transmission housing; a first, second, third, fourth and fifth gear set, wherein the first gear set includes a first gear in mesh with a second gear and a third gear, the second gear set includes a first gear in mesh with a second gear and a third gear, the third gear set includes a first gear in mesh with a second gear and a third gear, the fourth gear set includes a first gear in mesh with a second gear and the fifth gear set includes a first gear in mesh with a second gear; a first transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the third and fourth gear sets are rotatably fixed for common rotation with the first transmission input member and wherein the selective engagement of the first clutch of the dual clutch assembly transfers torque from the clutch housing to the first transmission input member; a second transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the first and second gear sets are rotatably fixed for common rotation with the second transmission input member and wherein the second transmission input member is concentric with the first transmission input member and at least partially surrounds the first transmission input member and wherein the selective engagement of the second clutch of the dual clutch assembly transfers torque form the clutch housing to the second transmission input member; a first countershaft rotatably supported within the transmission housing and spaced apart from and parallel with the first and second transmission input members, wherein the second gear of the first gear set, the third gear of the second gear set, the third gear of the third gear set and the second gear of the fourth gear set are each selectively connectable for common rotation with the first countershaft; a second countershaft rotatably supported within the transmission housing and spaced apart from and parallel with the first and second transmission input members, wherein the third gear of the first gear set, the second gear of the second gear set, the second gear of the third gear set and the first gear of the fifth gear set are each selectively connectable for common rotation with the second countershaft; a third countershaft rotatably supported within the transmission housing and spaced apart from and parallel with the first and second transmission input members, wherein the second gear of the fifth gear set is selectively connectable for common rotation with the third countershaft; and five synchronizer assemblies for selectively coupling at least one of the gears of the first, second, third, fourth and fifth gear sets with at least one of the first countershaft, the second countershaft and the third countershaft, and wherein the selective engagement of the first and second clutches of the dual clutch assembly interconnects the dual clutch housing with at least one of the first and the second transmission input members and the selective engagement of at least one of the five synchronizer assemblies establishes at least one of a forward or reverse speed ratio. ### Claim 2 (depends on 1) The transmission of claim 1 wherein a first of the five synchronizer assemblies selectively connects the second gear of the first gear set and the third gear of the second gear set to the first countershaft. ### Claim 3 (depends on 2) The transmission of claim 2 wherein a second of the five synchronizer assemblies selectively connects the third gear of the first gear set and the second gear of the second gear set to the second countershaft. ### Claim 4 (depends on 3) The transmission of claim 3 wherein a third of the five synchronizer assemblies selectively connects the third gear of the third gear set and the second gear of the fourth gear set to the first countershaft. ### Claim 5 (depends on 4) The transmission of claim 4 wherein a fourth of the five synchronizer assemblies selectively connects the second gear of the third gear set and first gear of the fifth gear set to the second countershaft. ### Claim 6 (depends on 5) The transmission of claim 5 wherein a fifth of the five synchronizer assemblies selectively connects the second gear of the fifth gear set to the third countershaft. ### Claim 7 (depends on 1) The transmission of claim 1 wherein the first gear set is adjacent the dual clutch assembly, the second gear set is adjacent the first gear set, the third gear set is adjacent the second gear set, the fourth gear set is disposed between the third gear set and an end wall of the transmission housing and the fifth gear set is co-planar with the fourth gear set. ### Claim 8 (depends on 1) The transmission of claim 1 further comprising a first countershaft transfer gear fixed to the first countershaft for common rotation with the first countershaft, a second countershaft transfer gear fixed to the second countershaft for common rotation with the second countershaft and a third countershaft transfer gear fixed to the third countershaft for common rotation with the third countershaft and wherein the first, second and third countershaft transfer gears transfer torque from at least one of the first, second and third countershafts to a transmission output member. ### Claim 9 (depends on 8) The transmission of claim 8 wherein the transmission output member is a gear that meshes with the each of the first, second and third countershaft transfer gears. ### Claim 10 (depends on 8) The transmission of claim 8 further comprising a park gear fixed to the third countershaft for common rotation with the third countershaft wherein the park gear is configured to prevent rotation of the third countershaft and third countershaft transfer gear. ### Claim 11 (depends on 1) The transmission of claim 1 wherein the first, second, third, fourth and fifth gear sets are separate gear sets having separate and distinct gears. ### Claim 12 A transmission comprising: a transmission housing; a dual clutch assembly having a first clutch, second clutch and a clutch housing connectable to an engine output member, wherein the clutch housing is rotationally supported within the transmission housing; a first, second, third, fourth and fifth gear set, wherein the first gear set includes a first gear in mesh with a second gear, the second gear set includes a first gear in mesh with a second gear and a third gear, the third gear set includes a first gear in mesh with a second gear and a third gear, the fourth gear set includes a first gear in mesh with a second gear, and the fifth gear set includes a first gear in mesh with a second gear; a first transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the third and fourth gear sets are rotatably fixed for common rotation with the first transmission input member and wherein the selective engagement of the first clutch of the dual clutch assembly transfers torque from the clutch housing to the first transmission input member; a second transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the first and second gear sets are rotatably fixed for common rotation with the second transmission input member and wherein the second transmission input member is concentric with the first transmission input member and at least partially surrounds the first transmission input member and wherein the selective engagement of the second clutch of the dual clutch assembly transfers torque form the clutch housing to the second transmission input member; a first countershaft rotatably supported within the transmission housing and spaced apart from and parallel with the first and second transmission input members, wherein the second gear of the first gear set, the third gear of the second gear set, the third gear of the third gear set and the second gear of the fourth gear set are each selectively connectable for common rotation with the first countershaft; a second countershaft rotatably supported within the transmission housing and spaced apart from and parallel with the first and second transmission input members, wherein the second gear of the second gear set, the second gear of the third gear set, the second gear of the third gear set and the first gear of the fifth gear set are each selectively connectable for common rotation with the second countershaft; a third countershaft rotatably supported within the transmission housing and spaced apart from and parallel with the first and second transmission input members, wherein the second gear of the fifth gear set is selectively connectable for common rotation with the third countershaft; a first countershaft transfer gear fixed to the first countershaft for common rotation with the first countershaft; a second countershaft transfer gear fixed to the second countershaft for common rotation with the second countershaft; a third countershaft transfer gear fixed to the third countershaft for common rotation with the third countershaft; a park gear fixed to the third countershaft for common rotation with the third countershaft wherein the park gear is configured to prevent rotation of the third countershaft and third countershaft transfer gear when engaged; and five synchronizer assemblies for selectively coupling at least one of the gears of the first, second, third, fourth and fifth gear sets with at least one of the first countershaft, the second countershaft and the third countershaft, and wherein the selective engagement of the first and second clutches of the dual clutch assembly interconnects the dual clutch housing with at least one of the first and the second transmission input members and the selective engagement of at least one of the five synchronizer assemblies transfers torque from at least one of the first, second, third, fourth and fifth gear sets to at least one of the first, second and third countershafts and to at least one of the first, second and third countershaft transfer gears to establish at least one of a forward or reverse speed ratio. ### Claim 13 (depends on 12) The transmission of claim 12 wherein a first of the five synchronizer assemblies selectively connects the second gear of the first gear set and the third gear of the second gear set to the first countershaft. ### Claim 14 (depends on 13) The transmission of claim 13 wherein a second of the five synchronizer assemblies selectively connects the third gear of the first gear set and the second gear of the second gear set to the second countershaft. ### Claim 15 (depends on 14) The transmission of claim 14 wherein a third of the five synchronizer assemblies selectively connects the third gear of the third gear set and the second gear of the fourth gear set to the first countershaft. ### Claim 16 (depends on 15) The transmission of claim 15 wherein a fourth of the five synchronizer assemblies selectively connects the second gear of the third gear set and first gear of the fifth gear set to the second countershaft. ### Claim 17 (depends on 16) The transmission of claim 16 wherein a fifth of the five synchronizer assemblies selectively connects the second gear of the fifth gear set to the third countershaft. ### Claim 18 (depends on 12) The transmission of claim 12 wherein the first gear set is adjacent the dual clutch assembly, the second gear set is adjacent the first gear set, the third gear set is adjacent the second gear set, the fourth gear set is disposed between the third gear set and an end wall of the transmission housing and the fifth gear set is co-planar with the fourth gear set. ### Claim 19 (depends on 12) The transmission of claim 12 further comprising a transmission output member, wherein the transmission output member is a gear that meshes with the each of the first, second and third countershaft transfer gears. ### Claim 20 (depends on 12) The transmission of claim 12 wherein the first, second, third, fourth and fifth gear sets are separate gear sets having separate and distinct gears.