CN101893067A - Seven-gear double-clutch transmission - Google Patents

Abstract

A seven speed dual clutch transmission is connectable to an input member and has an output transfer gear, first and second transmission input shaft members, first and second 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 configured to provide at least one reverse speed ratio and a plurality of forward speed ratios between the input member and the output member.

Description

Seven-speed dual-clutch transmission

Cross References to Related Applications

This application claims the benefit of US Provisional Application No. 61/179905, filed May 20, 2009, which is hereby incorporated by reference in its entirety.

technical field

The present invention relates to transmissions, and more particularly to a compact dual clutch multi-speed transmission having at least three axes to establish seven or more gear speeds.

Background technique

The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.

A typical multispeed transmission with layshafts and co-planar gearsets uses layshaft gears with a different dedicated gear pair or set to achieve each forward speed ratio. Thus, the total number of gears required in this typical design is twice the number of gears for forward speeds, plus the three gears required for reverse. This results in a large number of required gear pairs, especially in transmissions having a large number of forward speed ratios.

While existing transmissions fulfill their intended purpose, the need for new and improved transmission configurations with improved performance—particularly in terms of efficiency, responsiveness and smoothness—and Improved packaging - mainly reduced size and weight. Accordingly, there is a need in the art for a transmission that has improved packaging while providing the desired gear ratio and torque range.

Contents of the invention

The present invention provides a transmission coupled to an input member and having an output member, first and second shaft members, first and second countershaft members, a park gear shaft, a plurality of co-planar gear sets, and a plurality of Torque transfer device. The torque transmitting devices include a plurality of gears, a synchronizer assembly and a dual clutch assembly. The transmission is capable of providing at least one reverse speed ratio and a plurality of forward speed ratios between the input member and the output member.

In one aspect of the invention, the transmission includes a transmission housing.

In another aspect of the present invention, the transmission includes a dual clutch assembly having a first clutch, a second clutch, and a clutch housing connectable to an engine output member. The clutch housing is rotatably supported within the transmission housing.

In another aspect of the present invention, the transmission includes first, second, third, fourth and fifth gear sets. The first gear set includes a first gear meshed with the second gear and a third gear meshed with the second gear, the second gear set includes a first gear meshed with the second gear and the third gear, the The third gear set includes a first gear that meshes with a second gear and a third gear, the fourth gear set includes a first gear that meshes with a second gear, and the fifth gear set also includes a gear that meshes with a second gear. first gear. The second gear of the fifth gear set is a stepped pinion having first and second gear tooth portions, and wherein the first gear tooth portion is larger than the second gear tooth portion and is identical to the fifth gear tooth portion The first gear of the set meshes.

In another aspect of the present invention, the transmission includes a first transmission input member rotatably supported in the transmission housing. Each of the first gears of the third, fourth and fifth gear sets are rotatably fixed for common rotation with the first transmission input member. Selective engagement of a first clutch of the dual clutch assembly transfers torque from the clutch housing to the first transmission input member.

In another aspect of the present invention, the transmission includes a second transmission input member rotatably supported in the transmission housing. Each of the first gears of the first and second gear sets is rotatably fixed for common rotation with the second transmission input member. The second transmission input member is concentric with and at least partially surrounds the first transmission input member. Selective engagement of a second clutch of the dual clutch assembly transfers torque from the clutch housing to the second transmission input member.

In another aspect of the present invention, the transmission includes a first countershaft rotatably supported within a transmission housing parallel to and spaced from the first and second transmission input members. The third 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 capable of communicating with the The first countershaft is selectively connected for common rotation.

In another aspect of the present invention, the transmission includes a second countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members . The second gear of the first gear set, the second gear of the second gear set, the second gear of the third gear set, and the second gear of the fifth gear set are each capable of communicating with the The second layshaft is selectively connected for common rotation.

In another aspect of the present invention, the transmission includes a first synchronizer assembly that couples at least one of the second gear of the first gear set and the second gear of the second gear set to One is selectively connected to the second countershaft.

In another aspect of the present invention, the transmission includes a second synchronizer assembly that couples at least one of the third gear of the first gear set and the third gear of the second gear set to One is selectively connected to the first countershaft.

In another aspect of the present invention, the transmission includes a third synchronizer assembly that connects the second gear of the third gear set to the second gear of the second gear of the fifth gear set. At least one of the gear teeth portions is selectively connected to the second layshaft.

In another aspect of the present invention, the transmission includes a fourth synchronizer assembly that connects at least one of the third gear of the third gear set and the second gear of the fourth gear set to One is selectively connected to the first countershaft.

In another aspect of the present invention, the transmission includes a first countershaft transfer gear and a second countershaft transfer gear, the first countershaft transfer gear being fixed to the first countershaft for common rotation with the first countershaft , and the second countershaft transfer gear is fixed to the second countershaft for common rotation with the second countershaft, and wherein the first and second countershaft transfer gears transfer torque from the first and second At least one of the layshafts transmits to the transmission output member.

In another aspect of the present invention, the transmission includes a park gear and a park transfer gear, the park gear is fixed to the first end of the park gear shaft, and the park transfer gear is fixed to the park The second end of the gear shaft. The park transfer gear meshes with the transmission output member. The park gear is configured to resist rotation of the transmission output member when the park gear is engaged.

In another aspect of the present invention, the selective engagement of the first and second clutches of the dual clutch assembly and the selective engagement of at least one of the synchronizer assemblies are in the first and second transmission input members At least one of seven forward speed ratios is established between at least one of said transmission output members.

Scheme 1. A transmission, comprising:

transmission case;

a dual clutch assembly having a first clutch, a second clutch, and a clutch housing connectable to an engine output member, wherein the clutch housing is rotatably supported within the transmission housing;

first, second, third, fourth and fifth gear sets, wherein the first gear set includes a first gear meshing with a second gear and a third gear meshing with the second gear, the first gear meshing with the second gear, The second gear set includes a first gear that meshes with a second gear and a third gear, the third gear set includes a first gear that meshes with a second gear and a third gear, and the fourth gear set includes a gear that meshes with a second gear. and the fifth gear set also includes a first gear meshing with a second gear, wherein the second gear of the fifth gear set is a stepped small gear having first and second gear tooth portions a gear, and wherein the first gear tooth portion is larger than the second gear tooth portion and meshes with the first gear of the fifth gear set;

a first transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the third, fourth and fifth gear sets are rotatable is fixed for common rotation with the first transmission input member, wherein 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 is rotatably connected to the said second transmission input member is fixed for common rotation, and wherein said second transmission input member is concentric with and at least partially surrounds said first transmission input member, and wherein said dual clutch assembly selective engagement of the second clutch transmits torque from the clutch housing to the second transmission input member;

A first countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the third of the first gear set gear, 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 with the first countershaft for common rotation;

A second countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the second gear, the second gear of the second gear set, the second gear of the third gear set, and the second gear of the fifth gear set are each selectively connectable with the second countershaft for co-spin; and

four synchronizer assemblies for coupling at least one of the gears of the first, second, third, fourth and fifth gear sets with the first countershaft and the at least one of the second countershafts is selectively coupled, and

wherein selective engagement of the dual clutch assembly interconnects the dual clutch housing with at least one of the first and second transmission input members, and selection of at least one of the four synchronizer assemblies Sexual engagement establishes at least one of the seven forward speed ratios.

Embodiment 2. The transmission of embodiment 1, wherein a first of the four synchronizer assemblies connects at least one of the second gear of the first gear set and the second gear of the second gear set to One is selectively connected to the second countershaft.

Embodiment 3. The transmission of embodiment 2, wherein a second of the four synchronizer assemblies connects at least one of the third gear of the first gear set and the third gear of the second gear set to One is selectively connected to the first countershaft.

Item 4. The transmission of item 3, wherein a third of said four synchronizer assemblies couples the second gear of said third gear set to the second gear of said fifth gear set. At least one of the gear teeth portions is selectively connected to the second layshaft.

Embodiment 5. The transmission of embodiment 4, wherein a fourth of said four synchronizer assemblies connects at least one of said third gear of said third gear set and said second gear of said fourth gear set to One is selectively connected to the first countershaft.

Item 6. The transmission of Item 1 wherein said first gear set is adjacent to said dual clutch assembly, said second gear set is adjacent to said first gear set, and said third gear set is adjacent to said first gear set Two gear sets, the fourth gear set is adjacent to the third gear set, and the fifth gear set is adjacent to the fourth gear set.

Clause 7. The transmission of clause 6, wherein said four synchronizer assemblies include a first synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The first synchronizer assembly is operable to selectively connect the second gear of the first gear set to the second layshaft to establish a second gear ratio as a second transmission input member.

Item 8. The transmission of item 6, wherein said four synchronizer assemblies include a first synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The first synchronizer assembly is operable to selectively connect the second gear of the second gear set to the second layshaft to establish a sixth gear ratio as the second transmission input member.

Item 9. The transmission of item 6, wherein said four synchronizer assemblies include a second synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The second synchronizer assembly is operable to selectively connect the third gear of the first gear set to the first countershaft to establish a reverse gear ratio when the second transmission is the input member.

Item 10. The transmission of item 6, wherein said four synchronizer assemblies include a second synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The second synchronizer assembly is operable to selectively connect the third gear of the second gear set to the first layshaft to establish a fourth gear ratio as the second transmission input member.

Clause 11. The transmission of clause 6, wherein said four synchronizer assemblies include a third synchronizer assembly when a first clutch of said dual clutch is engaged to connect said dual clutch housing to said The third synchronizer assembly is operable to selectively connect the second gear of the third gear set to the second layshaft to establish a fifth gear ratio when the first transmission input member is used.

Clause 12. The transmission of clause 6, wherein said four synchronizer assemblies include a third synchronizer assembly when a first clutch of said dual clutch is engaged to connect said dual clutch housing to said the third synchronizer assembly for selectively connecting the second gear tooth portion of the second gear of the fifth gear set to the second layshaft to establish a seventh gear ratio when the first transmission input member is active .

Item 13. The transmission of item 6, wherein said four synchronizer assemblies include a fourth synchronizer assembly, when said dual clutch second clutch is engaged to connect said dual clutch housing to said The fourth synchronizer assembly is operable to selectively connect the third gear of the third gear set to the first layshaft to establish a third gear ratio as the second transmission input member.

Clause 14. The transmission of clause 6, wherein said four synchronizer assemblies include a fourth synchronizer assembly when a first clutch of said dual clutch is engaged to connect said dual clutch housing to said The fourth synchronizer assembly is operable to selectively connect the second gear of the fourth gear set to the first layshaft to establish a first gear ratio when the first transmission input member is used.

Item 15. The transmission of item 1, further comprising a first countershaft transfer gear and a second countershaft transfer gear, the first countershaft transfer gear being fixed to the first countershaft so as to communicate with the first countershaft transfer gear shaft for common rotation, and the second countershaft transfer gear is fixed to the second countershaft for common rotation with the second countershaft, and wherein the first and second countershaft transfer gears transfer torque from the At least one of the first and second layshafts transmits to the transmission output member.

Clause 16. The transmission of clause 15 wherein said transmission output member is a gear that meshes with each of said first and second countershaft transfer gears.

Item 17. The transmission of item 15, further comprising a park gear fixed to the first end of the park gear shaft and a park drive gear fixed to the park drive shaft. the second end of the gear shaft, and wherein the park drive gear meshes with the transmission output member, and wherein the park gear is configured to prevent movement of the transmission output member when the park gear is engaged rotate.

Item 18. A transmission comprising:

transmission case;

a dual clutch assembly having a first clutch, a second clutch, and a clutch housing connectable to an engine output member, wherein the clutch housing is rotatably supported within the transmission housing;

first, second, third, fourth and fifth gear sets, wherein the first gear set includes a first gear meshing with a second gear and a third gear meshing with the second gear, the first gear meshing with the second gear, The second gear set includes a first gear that meshes with a second gear and a third gear, the third gear set includes a first gear that meshes with a second gear and a third gear, and the fourth gear set includes a gear that meshes with a second gear. and the fifth gear set also includes a first gear meshing with a second gear, wherein the second gear of the fifth gear set is a stepped small gear having first and second gear tooth portions a gear, and wherein the first gear tooth portion is larger than the second gear tooth portion and meshes with the first gear of the fifth gear set;

a first transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the third, fourth and fifth gear sets are rotatable is fixed for common rotation with the first transmission input member, wherein 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 is rotatably connected to the said second transmission input member is fixed for common rotation, and wherein said second transmission input member is concentric with and at least partially surrounds said first transmission input member, and wherein said dual clutch assembly selective engagement of the second clutch transmits torque from the clutch housing to the second transmission input member;

A first countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the third of the first gear set gear, 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 with the first countershaft for common rotation;

A second countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the second gear, the second gear of the second gear set, the second gear of the third gear set, and the second gear of the fifth gear set are each selectively connectable with the second countershaft for common rotation;

a first synchronizer assembly selectively connecting at least one of the second gear of the first gear set and the second gear of the second gear set to the second countershaft ;

a second synchronizer assembly selectively connecting at least one of the third gear of the first gear set and the third gear of the second gear set to the first countershaft ;

a third synchronizer assembly selectively connecting at least one of the second gear of the third gear set and the second gear tooth portion of the second gear of the fifth gear set to said second countershaft;

a fourth synchronizer assembly selectively connecting at least one of the third gear of the third gear set and the second gear of the fourth gear set to the first countershaft ;

a first countershaft transfer gear fixed to the first countershaft for common rotation therewith and a second countershaft transfer gear is fixed to the second countershaft for common rotation with the second countershaft, and wherein the first and second countershaft transfer gears transmit torque from at least one of the first and second countershafts to a transmission output member; and

a park gear and a park drive gear, the park gear being fixed to a first end of the park gear shaft and the park drive gear being fixed to a second end of the park gear shaft, and wherein the park a vehicle drive gear meshes with the transmission output member, and wherein the park gear is configured to prevent rotation of the transmission output member when the park gear is engaged, and

wherein selective engagement of the first and second clutches of the dual clutch assembly and selective engagement of at least one of the synchronizer assemblies is between at least one of the first and second transmission input members and the At least one of seven forward speed ratios is established between the transmission output members.

The above and other features and advantages of the present invention will become apparent through the following detailed description of the best mode for carrying out the present invention in conjunction with the accompanying drawings, in which the same reference numerals represent the same components, elements or features.

Description of drawings

FIG. 1 is a schematic diagram of one embodiment of a seven-speed transmission with a park gear mounted on a separate park shaft according to the present invention.

Detailed ways

Referring to FIG. 1 , a multi-speed transmission is indicated generally at 10 . The transmission 10 is coupled to an input member 12 and includes an output member or gear 14 . In this embodiment, the input member 12 is a shaft and the output member 14 is a gear, but those skilled in the art will appreciate that the input member 12 may be something other than a shaft and the output member 14 may be something other than a gear , such as an axis.

The input member 12 is continuously connected with an engine (not shown) or other torque producing machine that provides drive torque to the input member 12 . The output member or gear 14 rotatably drives a differential assembly 16 . Finally, a differential assembly 16 transmits the torque delivered by the output member 14 to a pair of wheels (not shown).

The transmission 10 includes a housing 18 at least partially enclosing a gear arrangement 20 . Gear apparatus 20 includes various shafts or members, intermeshing co-planar gear sets, dual clutch packs, and selectively engageable synchronizers, as will be described herein. For example, the gear arrangement 20 includes a first transmission input shaft or member 22 , a second transmission input shaft or member 24 , a first countershaft 26 , a second countershaft 28 , and a park gear shaft 30 . The second transmission input shaft or member 24 is a sleeve (hollow) shaft concentric with and overlying the first transmission input shaft or member 22 . The first countershaft 26 , the second countershaft 28 and the park gear shaft 30 are each parallel to and spaced apart from the first and second transmission input shaft members 22 , 24 . The first and second transmission input shafts 22 , 24 define a first axis of rotation, the first countershaft 26 defines a second axis of rotation, and the second countershaft 28 defines a third axis of rotation. The position and orientation of the countershafts 26 and 28 relative to the first and second transmission input shafts 22 , 24 are interchangeable.

A dual clutch assembly 32 is connected between the input member 12 and the first and second transmission input shaft members 22 , 24 . The dual clutch assembly 32 includes a clutch housing 34 connectable for common rotation with the input member 12 . Further, the dual clutch assembly 32 has first and second clutch elements or hubs 36 and 38 . Clutch elements 36 and 38 are configured with clutch housing 34 to form a friction clutch, commonly referred to in the art as a dual clutch. More specifically, clutch elements 36 , 38 and clutch housing 34 have friction plates mounted thereon or otherwise coupled thereto that interact to form a friction clutch. Clutch element 36 is connected for common rotation with the first transmission input shaft or member 22 and clutch element 38 is connected for common rotation with the second transmission input shaft or member 24 . Thus, selective engagement of the clutch element 36 with the clutch housing 34 connects the input member 12 for common rotation with the first transmission input shaft member 22 . Selective engagement of clutch element 38 with clutch housing 34 connects for common rotation the input member 12 with the second transmission input shaft member 24 . In FIG. 1 , the dual clutch assembly 32 is shown as a dry clutch assembly. It should be understood, however, that the dual clutch assembly 32 could be a wet clutch assembly without departing from the scope of the present invention.

The gear arrangement 20 also includes a plurality of co-planar gear sets 40 , 50 , 60 , 70 and 80 that mesh. The present invention contemplates that the meshing plurality of co-planar gear sets 40, 50, 60, 70 and 80 may be arranged axially along the transmission input shafts 22, 24 in a different order than that shown in FIG. within the scope of the present invention. Co-planar gear set 40 includes gear 42 , gear 44 and gear 46 . Pinion 42 is rotatably fixed and connected for common rotation with the second transmission input shaft member 24 . Gear 44 is selectively connectable for common rotation with the second countershaft member 28 and meshes with pinion 42 . Gear 46 is selectively connectable for common rotation with the first countershaft member 26 and intermeshes with gear 44 . It should be appreciated that the pinion 42 may be a separate gear structure fixed to the second transmission input shaft member 24, or may be a gear tooth/spline formed on the outer surface of the second transmission input shaft member 24, which does not depart from the scope of the present invention. The gear set 40 is disposed proximate to a wall 48 of the transmission housing 18 on the front or side of the transmission 10 proximate to the dual clutch assembly 32 .

Co-planar gear set 50 includes pinion 52 , gear 54 and gear 56 . Pinion 52 is rotatably fixed and connected for common rotation with the second transmission input shaft member 24 and meshes with gear 54 and gear 56 . Gear 54 is selectively connectable for common rotation with the second countershaft member 28 . Gear 56 is selectively connectable for common rotation with the first countershaft member 26 . Gear set 50 is positioned adjacent gear set 40 .

Co-planar gear set 60 includes pinion 62 , gear 64 and gear 66 . Pinion 62 is rotatably fixed and connected for common rotation with first transmission input shaft member 22 and meshes with gear 64 and gear 66 . Gear 64 is selectively connectable for common rotation with the second countershaft member 28 . Gear 66 is selectively connectable for common rotation with the first countershaft member 26 . Gear set 60 is disposed adjacent gear set 50 .

Co-planar gear set 70 includes pinion 72 and gear 74 . Pinion 72 is rotatably fixed and connected for common rotation with the first transmission input shaft member 22 and meshes with gear 74 . Gear 74 is selectively connectable for common rotation with the first countershaft member 26 . Gear set 70 is positioned adjacent gear set 60 .

Co-planar gear set 80 includes pinion 82 and gear 84 . Pinion 82 is rotatably fixed and connected for common rotation with the first transmission input shaft member 22 and meshes with gear 84 . Gear 84 is selectively connectable for common rotation with the second countershaft member 28 . Gear 84 includes a secondary or extension portion 84A kinematically connected to and fixed for common rotation with gear 84 . Gear set 80 is positioned between gear set 70 and an end wall 88 of the transmission housing 18 .

Further, a first countershaft transfer gear 100 is rotatably fixed and connected for common rotation with the first countershaft member 26 . A second countershaft transfer gear 110 is rotatably fixed and connected for common rotation with the second countershaft member 28 . Park transfer gear 111 is rotatably fixed and connected for common rotation with park gear shaft 30 . The first countershaft transfer gear 100 is configured to mesh with the output member 14 , the second countershaft transfer gear 110 is also configured to mesh with the output member 14 , and the park transfer gear 111 is likewise configured to mesh with the output member 14 . However, the first countershaft transfer gear 100 , the second countershaft transfer gear 110 and the park transfer gear 111 do not mesh with each other. The first countershaft transfer gear 100 is disposed between the co-planar gearset 40 and the end wall 48 of the transmission housing 18 . A second countershaft transfer gear 110 is also disposed between the co-planar gearset 40 and the end wall 48 of the transmission housing 18 . The park transfer gear 111 is disposed proximate to the wall 48 of the transmission housing 18 and is coplanar with the output gear or member 14 . In addition, the output member 14 is also coplanar with the first and second countershaft transfer gears 100 , 110 .

A park gear 112 is provided for placing the transmission 10 in a park mode which prevents the output member 14 from rotating. Park gear 112 is coupled to park transfer gear 111 through park gear shaft 30 . Alternatively, the present invention contemplates that the park gear is fixedly disposed on one of the first and second layshafts 26, 28 for the park mode function. In this embodiment, the park transfer gear 111 and the park gear shaft 30 are removed, which further improves the packaging capabilities of the transmission. Furthermore, the axial position of the park gear 112 along the layshaft 26 or 28 may be varied depending on the available packaging space.

With continued reference to FIG. 1 , the transmission 10 further includes a selectively engageable plurality of synchronizer assemblies 150 , 152 , 154 , and 156 . Synchronizers 150, 152, 154, and 156 are double-sided synchronizers and typically include shift forks (not shown) that are bidirectionally translatable by actuators (not shown) to at least two engaged positions and one idle position. gear or disengaged position. In the present embodiment, synchronizer 150 is selectively actuatable to connect gear 44 for common rotation with the second countershaft member 28 , and synchronizer 150 is selectively actuatable to connect gear 54 with the second countershaft member 28 . The countershaft members 28 are connected for common rotation. Synchronizer 152 is selectively actuatable to connect gear 46 for common rotation with the first countershaft member 26 , and synchronizer 152 is selectively actuatable to connect gear 56 with the first countershaft member 26 for common rotation. make it co-rotate. Synchronizer 154 is selectively actuatable to connect for common rotation gear 64 with the second countershaft 28 , and synchronizer 154 is selectively actuatable to couple gear extension 84A of gear 84 with the second countershaft. Members 28 are connected for common rotation. Synchronizer 156 is selectively actuatable to connect gear 66 for common rotation with the first countershaft member 26 , and synchronizer 156 is selectively actuatable to connect gear 74 with the first countershaft member 26 for common rotation. make it co-rotate.

The transmission 10 is capable of transmitting torque from the input shaft 12 to the output gear member 14 in at least seven forward torque ratios and at least one reverse torque ratio. Each of the forward and reverse torque ratios can be achieved by selectively engaging dual clutch assembly 32 and one or more of synchronizer assemblies 150 , 152 , 154 , and 156 . Those skilled in the art will readily appreciate that each torque ratio is associated with a different speed ratio.

It should be appreciated that each individual gearset 40, 50, 60, 70, and 80 is capable of providing one or more forward and/or reverse gears by selectively engaging synchronizer assemblies 150, 152, 154, and 156 gear ratio. It should also be understood that a particular forward or reverse speed ratio may be achieved by different combinations of synchronizers and associated gear sets without departing from the scope of the present invention.

For example, to establish a reverse torque ratio, clutch element 38 is engaged and synchronizer 152 is actuated. Clutch element 38 couples the input member 12 with the second transmission input shaft member 24 . Synchronizer 152 connects gear 46 to the first countershaft member 26 . More specifically, input torque from input shaft 12 is transferred through dual clutch assembly 32 to second transmission input shaft member 24 , through pinion 42 to gear 44 , through gear 44 to gear 46 , and from gear 46 through synchronizer 152 . Transmission is to the first countershaft member 26 which in turn is transmitted to the first countershaft transfer gear 100 and from the first countershaft transfer gear 100 to the output member 14 .

To establish a first forward torque ratio (ie, first gear), clutch element 36 is engaged and synchronizer 156 is actuated. Clutch element 36 couples the input member 12 with the first transmission input shaft member 22 . Synchronizer 156 couples gear 74 to the first countershaft member 26 . Input torque from the input member 12 is transferred through the dual clutch assembly 32 to the first transmission input shaft member 22 and on to the pinion 72 . Pinion 72 transmits torque to gear 74 which transmits torque via synchronizer 156 to first countershaft member 26 to first countershaft transfer gear 100 and from there to output member 14 .

To establish the second forward torque ratio (ie, second gear), clutch element 38 is engaged and synchronizer 150 is activated. Clutch element 38 couples the input member 12 to the second transmission input shaft member 24 which rotates pinion 42 . Synchronizer 150 couples gear 44 to the second countershaft member 28 . Correspondingly, input torque from input member 12 is transferred through dual clutch assembly 32 to second transmission input shaft member 24 , through pinion 42 to gear 44 , from gear 44 to synchronizer 150 , and from synchronizer 150 to second The second countershaft member 28 and from the second countershaft member 28 transmit to the second countershaft transfer gear 110 and the output member 14 .

To establish a third forward torque ratio (ie, third gear), clutch element 36 is engaged and synchronizer 156 is activated. Clutch element 36 couples the input member 12 to the first transmission input shaft member 22 which rotates pinion 62 . Synchronizer 156 couples gear 66 to the first countershaft member 26 . Thus, input torque from input member 12 is transferred through dual clutch assembly 32 to first transmission input shaft member 22 , through pinion 62 to gear 66 , through gear 66 to synchronizer 156 , and from synchronizer 156 to first The countershaft member 26 transmits from the first countershaft member 26 to the first countershaft transfer gear 100 and from the first countershaft transfer gear 100 to the output member 14 .

To establish a fourth forward torque ratio (ie, fourth gear), clutch element 38 is engaged and synchronizer 152 is activated. Clutch element 38 couples the input member 12 to the second transmission input shaft member 24 which rotates pinion 52 . Synchronizer 152 couples gear 56 to the first countershaft member 26 . Thus, input torque from input member 12 is transferred through dual clutch assembly 32 to second transmission input shaft member 24 to pinion 52, from pinion 52 to gear 56, from gear 56 to synchronizer 152, from synchronizer Drive 152 is transmitted to first countershaft member 26 , from first countershaft member 26 to first countershaft transfer gear 100 , and from first countershaft transfer gear 100 to output member 14 .

To establish the fifth forward torque ratio (ie, fifth gear), clutch element 36 is engaged and synchronizer 154 is activated. Clutch element 36 couples the input member 12 to the first transmission input shaft member 22 which rotates pinion 62 . Synchronizer 154 couples gear 64 to the second countershaft member 28 . Input torque from input member 12 is transferred through dual clutch assembly 32 to first transmission input shaft member 22, from first transmission input shaft member 22 to pinion 62, from pinion 62 to gear 64, from gear 64 through the synchronizer 154 is transmitted to the second countershaft member 28 which in turn is transmitted to the second countershaft transfer gear 110 and from the second countershaft transfer gear 110 to the output member 14 .

To establish a sixth forward torque ratio (ie, sixth gear), clutch element 38 is engaged and synchronizer 150 is activated. Clutch element 38 couples the input member 12 to the second transmission input shaft member 24 which rotates pinion 52 . Synchronizer 150 couples gear 54 to the second countershaft member 28 . Thus, input torque from input member 12 is transferred through dual clutch assembly 32 to second transmission input shaft member 24 to pinion 52, from pinion 52 to gear 54, from gear 54 to synchronizer 150, and from synchronizer 150 to the second countershaft member 28 , from the second countershaft member 28 to the second countershaft transfer gear 110 , and from the second countershaft transfer gear 110 to the output member 14 .

To establish the seventh forward torque ratio (ie, seventh gear), clutch element 36 is engaged and synchronizer 154 is activated. Clutch element 36 couples the input member 12 to the first transmission input shaft member 22 which rotates pinion 62 . Synchronizer 154 couples gear 84 to the second countershaft member 28 via extension 84A. Input torque from input member 12 is transferred through dual clutch assembly 32 to first transmission input shaft member 22, from first transmission input shaft member 22 to pinion 82, from pinion 82 to gear 84, from gear 84 through the synchronizer 154 is transmitted to the second countershaft member 28 which in turn is transmitted to the second countershaft transfer gear 110 and from the second countershaft transfer gear 110 to the output member 14 .

Again, it should be understood that any of the gear sets 40 , 50 , 60 , 70 and 80 may be varied to produce a particular forward and reverse torque ratio without departing from the scope of the present invention.

The present invention contemplates that various torque ratios (ie, the ratio of the torque of the output member 14 to the torque of the input member 12 ) and ratio steps can be achieved by selecting the number of teeth of the gears of the transmission 10 . The present invention has many advantages and benefits over the prior art. For example, the use of four synchronizers allows the use of four rails, with a fork on each rail. Thus, the present invention enables a transmission with simpler actuation and control systems, reduced mass and cost, and improved packaging.

While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.

Claims (10)

1. A speed changer, comprising: transmission case; a dual clutch assembly having a first clutch, a second clutch, and a clutch housing connectable to an engine output member, wherein the clutch housing is rotatably supported within the transmission housing; first, second, third, fourth and fifth gear sets, wherein the first gear set includes a first gear meshing with a second gear and a third gear meshing with the second gear, the first gear meshing with the second gear, The second gear set includes a first gear that meshes with a second gear and a third gear, the third gear set includes a first gear that meshes with a second gear and a third gear, and the fourth gear set includes a gear that meshes with a second gear. and the fifth gear set also includes a first gear meshing with a second gear, wherein the second gear of the fifth gear set is a stepped small gear having first and second gear tooth portions a gear, and wherein the first gear tooth portion is larger than the second gear tooth portion and meshes with the first gear of the fifth gear set; a first transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the third, fourth and fifth gear sets are rotatable is fixed for common rotation with the first transmission input member, wherein 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 is rotatably connected to the said second transmission input member is fixed for common rotation, and wherein said second transmission input member is concentric with and at least partially surrounds said first transmission input member, and wherein said dual clutch assembly selective engagement of the second clutch transmits torque from the clutch housing to the second transmission input member; A first countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the third of the first gear set gear, 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 with the first countershaft for common rotation; A second countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the second gear, the second gear of the second gear set, the second gear of the third gear set, and the second gear of the fifth gear set are each selectively connectable with the second countershaft for co-spin; and four synchronizer assemblies for coupling at least one of the gears of the first, second, third, fourth and fifth gear sets with the first countershaft and the at least one of the second countershafts is selectively coupled, and wherein selective engagement of the dual clutch assembly interconnects the dual clutch housing with at least one of the first and second transmission input members, and selection of at least one of the four synchronizer assemblies Sexual engagement establishes at least one of the seven forward speed ratios. 2. The transmission of claim 1 wherein a first of said four synchronizer assemblies connects at least one of said second gear of said first gear set and said second gear of said second gear set to One is selectively connected to the second countershaft. 3. The transmission of claim 2 wherein a second of said four synchronizer assemblies connects at least the third gear of said first gear set and the third gear of said second gear set One is selectively connected to the first countershaft. 4. The transmission of claim 3 wherein a third of said four synchronizer assemblies couples the second gear of said third gear set to the second gear of said fifth gear set. At least one of the gear teeth portions is selectively connected to the second layshaft. 5. The transmission of claim 4 wherein a fourth of said four synchronizer assemblies connects at least one of said third gear of said third gear set and said second gear of said fourth gear set to One is selectively connected to the first countershaft. 6. The transmission of claim 1 wherein said first gear set is adjacent said dual clutch assembly, said second gear set is adjacent said first gear set, said third gear set is adjacent said first gear set Two gear sets, the fourth gear set is adjacent to the third gear set, and the fifth gear set is adjacent to the fourth gear set. 7. The transmission of claim 6, wherein said four synchronizer assemblies include a first synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The first synchronizer assembly is operable to selectively connect the second gear of the first gear set to the second layshaft to establish a second gear ratio as a second transmission input member. 8. The transmission of claim 6, wherein said four synchronizer assemblies include a first synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The first synchronizer assembly is operable to selectively connect the second gear of the second gear set to the second layshaft to establish a sixth gear ratio as the second transmission input member. 9. The transmission of claim 6 wherein said four synchronizer assemblies include a second synchronizer assembly when a second clutch of said dual clutch is engaged to connect said dual clutch housing to said The second synchronizer assembly is operable to selectively connect the third gear of the first gear set to the first countershaft to establish a reverse gear ratio when the second transmission is the input member. 10. A transmission comprising: transmission case; a dual clutch assembly having a first clutch, a second clutch, and a clutch housing connectable to an engine output member, wherein the clutch housing is rotatably supported within the transmission housing; first, second, third, fourth and fifth gear sets, wherein the first gear set includes a first gear meshing with a second gear and a third gear meshing with the second gear, the first gear meshing with the second gear, The second gear set includes a first gear that meshes with a second gear and a third gear, the third gear set includes a first gear that meshes with a second gear and a third gear, and the fourth gear set includes a gear that meshes with a second gear. and the fifth gear set also includes a first gear meshing with a second gear, wherein the second gear of the fifth gear set is a stepped small gear having first and second gear tooth portions a gear, and wherein the first gear tooth portion is larger than the second gear tooth portion and meshes with the first gear of the fifth gear set; a first transmission input member rotatably supported in the transmission housing and wherein each of the first gears of the third, fourth and fifth gear sets are rotatable is fixed for common rotation with the first transmission input member, wherein 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 is rotatably connected to the said second transmission input member is fixed for common rotation, and wherein said second transmission input member is concentric with and at least partially surrounds said first transmission input member, and wherein said dual clutch assembly selective engagement of the second clutch transmits torque from the clutch housing to the second transmission input member; A first countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the third of the first gear set gear, 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 with the first countershaft for common rotation; A second countershaft rotatably supported within the transmission housing parallel to and spaced apart from the first and second transmission input members, wherein the second gear, the second gear of the second gear set, the second gear of the third gear set, and the second gear of the fifth gear set are each selectively connectable with the second countershaft for common rotation; a first synchronizer assembly selectively connecting at least one of the second gear of the first gear set and the second gear of the second gear set to the second countershaft ; a second synchronizer assembly selectively connecting at least one of the third gear of the first gear set and the third gear of the second gear set to the first countershaft ; a third synchronizer assembly selectively connecting at least one of the second gear of the third gear set and the second gear tooth portion of the second gear of the fifth gear set to said second countershaft; a fourth synchronizer assembly selectively connecting at least one of the third gear of the third gear set and the second gear of the fourth gear set to the first countershaft ; a first countershaft transfer gear fixed to the first countershaft for common rotation therewith and a second countershaft transfer gear is fixed to the second countershaft for common rotation with the second countershaft, and wherein the first and second countershaft transfer gears transmit torque from at least one of the first and second countershafts to a transmission output member; and a park gear and a park drive gear, the park gear being fixed to a first end of the park gear shaft and the park drive gear being fixed to a second end of the park gear shaft, and wherein the park a vehicle drive gear meshes with the transmission output member, and wherein the park gear is configured to prevent rotation of the transmission output member when the park gear is engaged, and wherein selective engagement of the first and second clutches of the dual clutch assembly and selective engagement of at least one of the synchronizer assemblies is between at least one of the first and second transmission input members and the At least one of seven forward speed ratios is established between the transmission output members.

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