CN102047001A

CN102047001A - Double-clutch transmssion for vehicles

Info

Publication number: CN102047001A
Application number: CN200980120084XA
Authority: CN
Inventors: 迈克尔·B·莫琳; 阿克塞尔·盖伯格; 马塞厄斯·雷姆勒; 马库斯·罗肯巴克
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2008-03-31
Filing date: 2009-03-31
Publication date: 2011-05-04
Also published as: CN102047004A

Abstract

The dual-clutch transmission (DCT) (1) includes an inner input shaft (20) within an outer input shaft (22). Two clutch discs (8, 10) are connected to the input shafts (20, 22), respectively. Three countershafts (38, 40, 50) of the DCT (1) are parallel to the input shafts (20, 22), one of which has a pinion (41, 51) at its end. The gears on the shafts (20, 22, 38, 40, 50) comprise seven gear sets for providing seven incremental forward gears. Each gear set includes a fixed gear on the inner input shaft (20) that meshes with an idler gear on one of the countershafts (38, 40, 50) for providing a forward gear. A fourth fixed gear (31) meshes with a fourth idler gear (63) and a sixth idler gear (65). In particular, the DCT (1) also includes a dual-meshing transmission (1) which further includes a parking lock gear (39) fixed to one of the countershafts (38, 40, 50) that carries the final drive pinion (41, 51).

Description

Dual clutch transmission for a vehicle

Technical Field

The present invention relates to a dual clutch transmission for a vehicle, such as an automobile.

Background

A Dual Clutch Transmission (DCT) includes two input shafts that are individually connected to and actuated by two clutches. These two clutches are typically combined into a single device, allowing either of the two clutches to be actuated at a time. The two clutches transfer drive torque from the engine to the two input shafts of the dual clutch transmission.

Volkswagon has provided a 7-speed dual clutch transmission

Referred to as DQ 200. TheDQ200 provides an attempt to set a 7-speed dual clutch transmission in an automobile for street driving.

DCT has not yet been widely applied in cars for street driving. Problems that prevent the application of DCTs to street driving include providing DCTs that are compact, reliable, and fuel efficient. Accordingly, there is a need to provide such dual clutch transmissions that are affordable to consumers.

Disclosure of Invention

A Dual Clutch Transmission (DCT) is provided having an inner input shaft and an outer input shaft. The outer input shaft surrounds a portion of the inner input shaft. The outer input shaft surrounds the inner input shaft in a radial direction. The radial direction refers to the area around the longitudinal axis of the inner input shaft. The outer input shaft may be a hollow input shaft and the inner input shaft may be a solid input shaft. Alternatively, the inner input shaft may also be a hollow input shaft.

The DCT includes a first clutch plate non-rotatably connected to the inner input shaft and a second clutch plate non-rotatably connected to the outer input shaft. For example, the first clutch plate is fixed to the inner input shaft and the second clutch plate is fixed to the outer input plate. Alternatively, the universal joint may provide a non-rotatable connection.

The DCT includes a first, second, and third layshaft, which are radially spaced from and disposed parallel to the input shaft. That is, the longitudinal axes of the shafts are parallel to each other, including the overlapping axes. One or more of the layshafts includes a pinion as the final drive. The pinion gear may be engaged with an output gear on the output shaft for outputting drive torque to a drive train of the vehicle. The drive train, which may alternatively be referred to as a drive train or power plant, includes a set of components that generate and transmit power to the road surface, water or air. The drive train includes an engine, a transmission, a driveshaft, a differential and a final drive. The final drive may include drive wheels, continuous tracks such as tanks or track type tractors, propellers, etc.

The gears of the DCT are disposed on the first countershaft, the second countershaft, the third countershaft, the inner input shaft, and the outer input shaft. The gears include a first gear set, a second gear set, a third gear set, a fourth gear set, a fifth gear set, a sixth gear set, and a seventh gear set for providing seven incremental forward gears. The gear of the DCT may refer to an output speed range of the output gear. The increasing gears describe an increasing sequence in which the elements follow each other. The gears of the vehicle are typically arranged in successively increasing fashion from first gear to seventh gear. The gear ratio (gear ratio) of the DCT is correspondingly reduced from first gear to seventh gear. For example, in a vehicle with a seven speed DCT, first gear has a gear ratio of 2.97: 1. Second gear has a gear ratio of 2.07: 1. Third gear has a gear ratio of 1.43: 1. Fourth gear has a gear ratio of 1.00: 1. Fifth gear has a gear ratio of 0.84: 1. Sixth gear has a gear ratio of 0.56: 1. The last seven gears have a gear ratio of 0.42: 1. Seven gears provide an increasing sequence of output speed ranges of the transmission for driving a vehicle having a DCT.

The first gear set includes a first fixed gear on the inner input shaft that meshes with a first gear idler gear on one of the layshafts for providing a first forward gear. The third gear set includes a third fixed gear on the inner input shaft that meshes with a third idler gear on one of the layshafts for providing a third forward speed. The fifth gear set includes a fifth fixed gear on the inner input shaft that meshes with a fifth gear idler gear on one of the layshafts for providing a fifth forward gear. The seventh gear set includes a seventh fixed gear on the inner input shaft that meshes with a seventh gear idler gear on one of the layshafts for providing a seventh forward gear.

The second gear set comprises a second fixed gear on the outer input shaft which meshes with a second gear idler gear on one of the layshafts for providing a second forward gear. The fourth gear set includes a fourth fixed gear on the outer input shaft that meshes with a fourth gear idler gear on one of the layshafts for providing a fourth forward gear. The sixth gear set includes a sixth fixed gear on the outer input shaft that meshes with a sixth gear idler gear on one of the layshafts for providing a sixth forward gear.

One or more of the gear sets includes a coupling device disposed on one of the countershafts to selectively engage one of the gears for selecting one of the seven gears. The fourth fixed gear is also meshed with a sixth gear idler gear.

The dual clutch transmission may also include a park-lock gear fixed to one of the layshafts carrying the pinion as a final drive pinion for engaging and locking a differential of the DCT. The differential includes an output gear on an output shaft. The park lock allows a vehicle having the park lock to park at a location, even on a slope, in a safe manner. The parking lock is easy to implement and is advantageous for vehicle and passenger safety.

The DCT provides seven forward gears through the dual clutch. The DCT makes gear shifting between odd-numbered gears and even-numbered gears quick and efficient because the gears of the odd-numbered gears and the even-numbered gears are driven by different clutch discs or different clutches, respectively. A double meshing arrangement is provided by a fourth fixed gear meshing with a fourth gear idler gear and a sixth gear idler gear. The dual mesh configuration makes the DCT compact, lightweight, and low cost because two fixed gears are eliminated on the input shaft. The idler gear and coupling arrangement together may replace a fixed gear on one of the input shafts. Similarly, if an idler gear wheel and coupling arrangement is provided on one of the layshafts for engagement with a fixed gear wheel on one of the layshafts, the idler gear wheel on one of the layshafts may be replaced by the fixed gear wheel.

In this application, one of the lower fixed gears on one of the input shafts may be mounted closer to the clutch plate end of the input shaft than the other higher fixed gear. The clutch disk end of the input shaft is the end of the input shaft for coupling with the two clutch disks. The idler gear of the lower gear on one of the layshafts is larger than the idler gear of the higher gear. Since the clutch housing has a large compartment around the pinion and the clutch end, the compartment can be used to enclose a large low-range idler gear. Thus, the clutch housing that encloses the layshaft end without the pinion can be made smaller, which allows the dual clutch transmission to be made more compact. This therefore facilitates bringing the low gear idler gear closer to the pinion on the same layshaft.

Since the idler gear and the fixed gear of the same gear are meshed with each other, it is advantageous to mount the fixed gear of the lower gear closer to the clutch disc end of the input shaft.

In one embodiment, the present application may provide a seventh idler gear on the second layshaft to be furthest from the pinion gear than other idler gears on the same layshaft. In another embodiment, the present application may provide that the seventh fixed gear is farther from the clutch disc end of the input shaft than the first fixed gear.

One of the low range idler gears is closer to the pinion than the other high range idler gear on their common layshaft.

In the present application, two different input shafts may drive or provide first forward and reverse gears, respectively. The double clutch of the DCT makes it possible to switch between the two input shafts quickly. Thus, a drive strategy in which the DCT alternately engages the two input shafts may drive the vehicle to move rapidly forward and backward. This strategy is advantageous for moving the vehicle out of the puddle because the vehicle can simply be driven forward and backward to exit the puddle. The loss of momentum of the gears and layshafts of the DCT can be small. Alternatively, forward and backward movement may be achieved by a second forward gear and a first reverse gear on different input shafts.

In this application, the gears may also include a reverse gear set, including a reverse fixed gear on one of the input shafts, which meshes with a first reverse gear on the third layshaft, for receiving an input reverse torque. The reverse gear set may further include a second reverse gear wheel on the third layshaft engaged with one of the idler wheels on one of the first and second layshafts for outputting the received reverse torque to the pinion. The reverse gear set may also include a coupling device on one of the countershafts to engage the gear in reverse for selecting reverse gear. Reverse gear makes a vehicle with a DCT more operational.

The dual clutch transmission device may include two pinions mounted on the two layshafts, respectively. The two pinions may mesh or mesh with a relatively large output gear on the output shaft. The output gear may be integrated into the gearbox differential without providing an intermediate output shaft of the gearbox. This allows for a very dense packing situation for the DCT.

According to the present application, two or more of the first gear idler gear, the second gear idler gear and the third gear idler gear are mounted on the same countershaft. Mounting low range idler gears (such as first, second and third range idler gears) on the same shaft requires that the countershaft be strong and robust. The remaining layshafts of the dual clutch transmission (except for the layshaft carrying the reverse idler gear) can thus be made thin at low cost for carrying the high range gears. For example, two or more of the fourth gear idler gear, the fifth gear idler gear, the sixth gear idler gear, and the seventh gear multiple gear may be mounted on the same countershaft.

The dual clutch transmission may also include bearings for supporting the countershafts. One or more of the bearings are disposed proximate the pinion gear. The immediately adjacent bearings reduce the deflection of the layshaft under load to better support the pinion that outputs its torque carrying layshaft. The support shaft can thereby improve transmission torque transmission efficiency and reduce the cost of the DCT.

One or more of the bearings are disposed adjacent one of the driven gears of the lower range. The low gear transmits a larger torque than the high gear. The close support of the bearings helps to reduce excessive deflection and the cost associated with their mass carrying the shaft.

A transmission includes a dual clutch transmission and an output gear on an output shaft. The output gear is engaged with the pinion gear for outputting the driving torque to the torque output member. The output gear may even mesh with each pinion. The output gear provides a single source of torque output to make the DCT simple and uncluttered in construction.

The present application provides a driveline device having a gearbox. One or more of the power sources generates drive torque. The drive train arrangement typically has a gearbox and an onboard power source, so that the vehicle with the drive train arrangement can move rather than being physically attached to an external stationary power source.

The power source may include an internal combustion engine. The drive train with the internal combustion engine and the DCT is easy to manufacture. Internal combustion engines consume less gasoline to protect the environment. Furthermore, internal combustion engines for other types of fuels may have even less polluting emissions, such as hydrogen fuel.

The power source may comprise an electric motor. Electric motors used in hybrid vehicles or electric vehicles result in reduced pollution compared to typical combustion using gasoline. The electric motor may recover braking energy even in generator mode.

According to the present application, there is also provided a vehicle comprising a driveline device. Vehicles with a driveline arrangement are efficient in energy usage by using a dual clutch transmission.

The dual clutch transmission enables gear preselection for smooth gear shifting. The two coupling devices can engage simultaneously the idler gear of the current gear and the idler gear of the next successive gear. This allows the next successive gear to be connected quickly and thus in a smoother manner. In particular, two idler gears of two consecutive gears driven by different input shafts of the DCT may be engaged simultaneously. For example, when only one input shaft receives input torque, the idler gears of the fourth and fifth gears of the DCT may each be engaged to their load carrying weight layshafts through their respective coupling devices. One engaged idler gear is directly driven by input torque, and the other engaged idler gear is driven by input torque via a pinion. In this way, there is little or no interruption in torque flow during the shift. Thus, the dual clutch transmission provides continuous and more efficient torque transfer compared to the shift process of other single clutch transmissions.

Drawings

FIG. 1 illustrates a front view of a first embodiment of a dual clutch transmission of the present application;

FIG. 2 illustrates a torque flow path for the first gear ratio;

FIG. 3 illustrates a torque flow path for the second gear ratio;

FIG. 4 illustrates a torque flow path for the third gear ratio;

FIG. 5 illustrates a torque flow path for the fourth speed ratio;

FIG. 6 illustrates a torque flow path for the fifth speed ratio;

FIG. 7 illustrates the torque flow path for the six speed ratio;

FIG. 8 illustrates torque flow paths for a seven speed transmission ratio;

FIG. 9 illustrates the torque flow path for the reverse speed ratio;

FIG. 10 shows an assembly of a double-sided linkage with gears adjacent thereto for engagement;

FIG. 11 shows an assembly of a single-sided coupling device with gears adjacent thereto for engagement;

FIG. 12 illustrates an assembly of an idler gear rotatably supported by a shaft on bearings;

FIG. 13 shows an assembly of fixed gears supported on a shaft;

FIG. 14 shows a detailed cross section of a crankshaft of an internal combustion engine according to an embodiment of a dual clutch transmission;

FIG. 15 illustrates a front view of another embodiment of the dual clutch transmission of the present application;

FIG. 16 shows an expanded side view of the dual clutch transmission of FIG. 15;

FIG. 17 illustrates a front view of another embodiment of the dual clutch transmission of the present application;

FIG. 18 shows a developed side view of the dual clutch transmission of FIG. 17.

Reference numerals of fig. 1-14

1 double-clutch gearbox

4 Clutch housing

5 clutch disc end of input shaft

8 inner clutches or inner clutch discs

10 outer clutch or outer clutch disc

12 output gear

14 output shaft

20 solid input shaft

22 hollow input shaft

24 first gear fixed wheel

25 three-gear fixed wheel

26 five-gear fixed wheel

27 seven-gear fixed wheel

30 second gear fixed wheel

31 four-gear fixed wheel

32 six-gear fixed wheel

35 first reverse gear

36 second reverse gear wheel

37 reverse gear idler

38 reverse gear idler shaft

39 parking lock gear

40 upper auxiliary shaft

41 upper pinion

50 lower auxiliary shaft

51 lower pinion

60 first-gear idler wheel

61 second gear idler

62 three-gear idler wheel

63 four-gear idler

64 five-gear idler

65 six-gear idler

66 seven-gear idler

71 solid shaft bearing

72 hollow shaft bearing

73 countershaft bearing

74 idler shaft bearing

81 double-side coupling device

82 double-sided coupling device

83 double-sided coupling device

84 double-sided coupling device

100 assembly of two-sided coupling device

101 idler

102 coupling device

103 idler pulley

104 axle

110 assembly of single-sided coupling devices

112 gearshift mechanism

113 idler pulley

114 shaft

120 idler assembly

121 idler pulley

122 shaft

123 bearing

130 fixed gear assembly

131 axle

132 fixed gear

Reference numerals of fig. 15-16

1 double-clutch gearbox

3 side wall

4 Clutch housing

5 end of clutch plate

6 side wall

8 inner clutch disc

10 outer clutch disc

12 output gear

14 output shaft

20 solid input shaft

22 hollow input shaft

24 first gear fixed wheel

25 three-gear fixed wheel

26 five-gear fixed wheel

27 seven-gear fixed wheel

30 second gear fixed wheel

31 four-gear fixed wheel

32 six-gear fixed wheel

35 first reverse gear

36 second reverse gear wheel

37 reverse gear idler

38 reverse gear idler shaft

39 parking lock gear

40 upper auxiliary shaft

41 upper pinion

50 lower auxiliary shaft

51 lower pinion

60 first-gear idler wheel

61 second gear idler

62 three-gear idler wheel

63 four-gear idler

64 five-gear idler

65 six-gear idler

66 seven-gear idler

71 solid shaft bearing

72 hollow shaft bearing

73 countershaft bearing

74 idler shaft bearing

80 double-side coupling device

81 double-side coupling device

82 double-sided coupling device

83 double-sided coupling device

Reference numerals of fig. 17

1 double-clutch gearbox

3 side wall

4 Clutch housing

5 end of clutch plate

7 side wall

8 inner clutch disc

10 outer clutch disc

12 output gear

14 output shaft

20 solid input shaft

22 hollow input shaft

24 first gear fixed wheel

25 three-gear fixed wheel

26 five-gear fixed wheel

27 seven-gear fixed wheel

30 second gear fixed wheel

31 four-gear fixed wheel

32 six-gear fixed wheel

35 first reverse gear

36 second reverse gear wheel

37 reverse gear idler

38 reverse gear idler shaft

39 parking lock gear

40 upper auxiliary shaft

41 upper pinion

50 lower auxiliary shaft

51 lower pinion

60 first-gear idler wheel

61 second gear idler

62 three-gear idler wheel

63 four-gear idler

64 five-gear idler

65 six-gear idler

66 seven-gear idler

71 solid shaft bearing

72 hollow shaft bearing

73 countershaft bearing

74 idler shaft bearing

80 double-side coupling device

81 double-side coupling device

82 double-sided coupling device

83 double-sided coupling device

Detailed Description

In the following description, embodiments of the present application will be described in detail. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details.

Fig. 1-14 provide detailed descriptions of embodiments of Dual Clutch Transmissions (DCTs) of the present application. Fig. 1-14 include similar components, with similar reference numerals. The relevant description of similar components is incorporated where necessary.

Fig. 1 shows a front view of an exemplary embodiment of a dual clutch transmission 1 according to the present application. The DCT 1 includes a reverse idler shaft 38, an upper pinion 41 on an upper layshaft 40, two

input shafts

20, 22, a lower pinion 51 on a lower layshaft 50, and a larger output gear 12 on an output shaft 14. The two

input shafts

20, 22 include an inner input shaft 20 and an outer input shaft 22. The inner input shaft 20 is a solid input shaft 20 (i.e., K1) and the outer input shaft is a hollow input shaft 22 (i.e., K2). The solid input shaft 20 and the hollow input shaft 22 share the same longitudinal axis of rotation. Two pinion gears 41, 51 are fixed to the right ends of the upper and lower

auxiliary shafts

40, 50, respectively. The output gear 12 is also fixed to an output shaft 14 along its axis of rotation. The two

pinions

41, 51 individually mesh with the output gear 12 at different positions of the output gear 12.

The reverse idler shaft 38, the upper layshaft 40 and the lower layshaft 50 are parallel to the

coaxial input shafts

20, 22 with a predetermined distance therebetween. These distances are arranged in radial direction of the axes, as better seen in fig. 2. Other gears are mounted on these shafts according to a predetermined pattern and mesh with each other. The manner in which these gears are mounted and engaged is better seen in the following figures.

Fig. 1 also shows a cutting plane a-a for showing an expanded cross-sectional view through the DCT 1, which DCT is shown in fig. 2 to 9. The cutting plane A-A passes through the rotational axes of the reverse shaft 38, the upper layshaft 40, the

input shafts

20, 22, the lower layshaft 50, and the output shaft 14. One of the purposes of fig. 2 to 9 is to further illustrate the structure and torque flow of the DCT 1.

Fig. 2 shows an expanded view of the DCT, showing the manner of gear mounting, and corresponds to fig. 1.

According to fig. 2, the DCT 1 comprises, from top to bottom, a reverse shaft 38, an upper layshaft 40, a hollow input shaft 22, a solid input shaft 20, a lower layshaft 50, and an output shaft 14. The solid input shaft 20 is partially disposed within the hollow input shaft 22. The solid input shaft 20 also protrudes beyond the hollow input shaft 22 at both ends thereof. The hollow input shaft 22 is mounted to the solid input shaft 20 by a pair of solid shaft bearings 71, the pair of solid shaft bearings 71 being disposed between the solid input shaft 20 and the hollow input shaft 22 at both ends of the hollow input shaft 22. Thus, the two

input shafts

20, 22 are coupled together such that the solid input shaft 20 rotates freely within the hollow input shaft 22. The hollow input shaft 22 surrounds a right portion of the solid input shaft 20, while a left portion of the solid input shaft 20 is exposed outside the hollow input shaft 22. The assembly of the

input shafts

20, 22 is supported on the left by a solid shaft bearing 71 at the projecting end of the solid shaft 20 and on the right by a hollow shaft bearing 72 on the hollow input shaft 22.

According to fig. 2, the outer input shaft 22 surrounds a portion of the solid input shaft 22 in a radial direction of the solid input shaft 20. The radial direction is perpendicular to the common longitudinal axis of the

input shafts

20, 22. There are four gears fixed to the left exposed portion of the solid input shaft 20. These gears are, from left to right, successively a first-gear fixed gear 24, a seventh-gear fixed gear 27, a third-gear fixed gear 25 and a fifth-gear fixed gear 26. Each of the first-gear fixed sheave 24, the seventh-gear fixed sheave 27, the third-gear fixed sheave 25, and the fifth-gear fixed sheave 26 is coaxially mounted to the solid input shaft 20. Mounted on the right portion of the solid input shaft 20 is a hollow input shaft 22 to which are attached from left to right a fourth gear fixed wheel 31 and a second gear fixed wheel 30. The fourth-gear fixed wheel 31 also serves as the sixth-gear fixed wheel 31. Each of the fourth-gear fixed wheel 31 and the second-gear fixed wheel 30 is coaxially fixed on the hollow input shaft 22.

An upper layshaft 40 is disposed above the

input shafts

20, 22. On the upper layshaft 40 there are gears, couplings and bearings. These include, from right to left, the upper pinion 41, the layshaft bearing 73, the reverse idler 37, the double-sided coupling 81, the sixth idler 65, the fifth idler 64, the double-sided coupling 82, the seventh idler 66, and the layshaft bearing 73.

The reverse idler 37, the sixth idler 65, the fifth idler 64 and the seventh idler 66 are each mounted on the upper layshaft 40 by bearings so that these gears rotate freely about the upper layshaft 40. The double-sided coupling 81 is movable along the upper layshaft 40 to engage either of 37 and 65 to the upper layshaft 40. Similarly, the double-sided coupling 82 is movable along the upper layshaft 40 to engage either of the fifth-gear idler 64 and the seventh-gear idler 66 to the upper layshaft 40. The sixth idler 65 meshes with the sixth fixed sheave 32. The fifth idler gear 64 meshes with the fifth fixed gear 26. The seventh-speed idler 66 meshes with the seventh-speed fixed pulley 27.

The reverse idler shaft 38 is also disposed above the upper layshaft 40. From right to left, the idler shaft bearing 74, the first reverse gear 35, the second reverse gear 36, and the idler shaft bearing 74 are mounted to the reverse shaft 38. Both the first reverse gear 35 and the second reverse gear 36 are coaxially fixed to the reverse idler shaft 38, so that the first reverse gear 35 and the second reverse gear 36 rotate together with the reverse idler shaft 38. The first reverse gear 35 is engaged with the second fixed gear 30. The second reverse gear 36 is engaged with the reverse gear 37.

The lower layshaft 50 is disposed below the

input shafts

20, 22. There are a number of components on the lower layshaft 50. These components include gears, linkages and bearings. These components, from right to left, include the lower pinion 51, the layshaft bearing 73, the second-speed idler 61, the double-sided coupling 84, the fourth-speed idler 63, the park lock gear 39, the third-speed idler 62, the double-sided coupling 83, the first-speed idler 60, and the layshaft bearing 73. The lower pinion 51 is fixed on its longitudinal axis to the lower layshaft 50. The second-speed idler 61, the fourth-speed idler 63, the third-speed idler 62, and the first-speed idler 60 are mounted on the lower counter shaft 50 through bearings, respectively, so that these gears become idlers and freely rotate around the lower counter shaft 50. In contrast, the parking lock gear 39 is coaxially fixed to the lower counter shaft 50.

The double-sided coupling 84 is movable along the lower layshaft 50 so that it can engage the second-gear idler 61 or the fourth-gear idler 63 to the lower layshaft 50. The double-sided coupling 83 is movable along the lower layshaft 50 so that it can engage the first-gear idler 60 or the third-gear idler 62, respectively, to the lower layshaft 50. The second-speed idler 61 is engaged with the second-speed fixed wheel 30. The fourth-speed idler 63 meshes with the fourth-speed fixed pulley 31. The third idler gear 62 meshes with the third fixed gear 25. The first-speed idler 60 meshes with the first-speed fixed wheel 24.

There are two dual-meshing structures in DCT 1. The first double engagement structure includes fourth-speed fixed wheel 31 engaged with both fourth-speed idler wheel 63 and sixth-speed idler wheel 65. The second double engagement structure includes the second fixed gear 30 engaged with both the first reverse gear 35 and the second idler gear 61.

The park lock gear 39 comprises a park lock on the lower layshaft 50 with the final drive pinion. The parking lock is a wheel provided with a ratchet device having a pawl device with a rack element, a claw or the like. The park lock keeps the lower layshaft 50, lower pinion 51, output gear 12 and output shaft 14 from rotating, which causes the vehicle with the DCT 1 to change from traveling to stopping when the vehicle is parked. The detailed structure of the parking lock is not shown in fig. 2.

The DCT 1 with a park lock is controlled by a shift lever that is positioned in the cab and is movable by the vehicle operator between positions corresponding to shift ranges, such as park, reverse, neutral, drive, and low. A linear actuation cable is attached at a first end thereof to the shift lever, and movement of the shift lever alternately pushes or pulls the cable to move a transmission mode select lever attached at the other end of the cable. The mode select lever is mechanically coupled to a shift valve in the DCT housing, and movement of the shift valve effects shifting between different gears.

When the gear lever is in the parking position, two related mechanical actuations occur in the DCT 1. First, the mode select lever is moved to disconnect the

input shafts

20, 22 from the engine. Second, the park lock pawl moves into locking engagement with the park lock gear 39 on the lower layshaft 50 to thereby lock the output shaft 14 against rotation. A linear actuation cable that actuates the mode select lever moves the pawl.

The distance 56 between the

input shafts

20, 22 and the upper layshaft 40 is measured from the common longitudinal axis of the

input shafts

20, 22 to the longitudinal axis of the upper layshaft 40. Similarly, the distance 58 between the

input shafts

20, 22 and the lower layshaft 50 is measured from the common longitudinal axis of the

input shafts

20, 22 to the longitudinal axis of the lower layshaft 50.

The output shaft 14 is also disposed below the lower countershaft 50. Two output shaft bearings 75 are respectively mounted at two opposite ends of the output shaft 14 for support. The output gear 12 is fixed coaxially to the output shaft 14 in the middle. The output gear 12 meshes with the lower pinion 51 and the upper pinion 41.

In this description, the expressions "meshing" and "meshing" (comb) are considered as synonyms with respect to a gearchange wheel or an engaged gear. In the usual case, a hollow shaft arranged within the hollow input shaft 2 may replace the solid input shaft 20. The term "coupling device" is referred to as a "shift mechanism" or "synchronizer" and is used to engage or disengage a gear on its carrier shaft. Dual Clutch Transmissions (DCTs) are alternatively referred to as dual clutches or Dual Clutch Transmissions (DCTs).

The first fixed gear 24 is also referred to as a first fixed gear 24. Similarly, the third fixed gear 25 is also referred to as a third fixed gear 25. The fifth fixed gear 26 is also referred to as a fifth fixed gear 26. The seventh fixed gear 27 is also referred to as a seventh fixed gear 27. The second fixed gear 30 is also referred to as a second fixed gear 30. The fourth fixed gear 31 is also referred to as a fourth fixed gear 31. The sixth fixed gear 32 is also referred to as a sixth fixed gear 32.

Further, the second reverse idle gear 35 is also referred to as a second reverse idle gear 35. The reverse idler gear 37 is also referred to as a reverse idler gear 37. The first-speed idler gear 60 is also referred to as a first-speed idler gear 60. The second-speed idler gear 61 is also referred to as a second-speed idler gear 61. The third idler gear 62 is also referred to as a third idler gear 62. The fourth-gear idler gear 63 is also referred to as a fourth-gear idler gear 63. The fifth idler gear 64 is also referred to as a fifth idler gear 64. The sixth-speed idler gear 65 is also referred to as a sixth-speed idler gear 65. The seventh idler gear 66 is also referred to as a seventh idler gear 66.

The output gear 12, the parking lock gear 39, the upper pinion 41, the lower pinion 51, and the reverse pinion 55 are also referred to as fixed wheels or gears. The first-speed fixed gear 24, the third-speed fixed gear 25, the fifth-speed fixed gear 26, the seventh-speed fixed gear 27, the second-speed fixed gear 30, the fourth-speed fixed gear 31, and the sixth-speed fixed gear 32 are also referred to as fixed gears or gears.

The upper pinion 41, the lower pinion 51 and the reverse pinion 55 are alternatively referred to as final drive pinions or final drives. The parking lock on the parking lock gear 39 may alternatively be provided on any of the

layshafts

38, 40, 50 having the last driving pinion. Either the

input shaft

20, 22 or the

layshaft

38, 40, 50 may be supported by more than two bearings.

In the drawings of the present application, broken lines indicate alternate positions of the components shown or the meshing relationship between the gears.

The present application provides a DCT 1 that allows a shift operation with reduced loss of drive torque. This is because the shifting operation can be achieved by selectively connecting one of the two clutch discs 8, 10 of the DCT 1. Thus, an associated additional primary drive clutch may be avoided. This selective connection between the two clutch discs 8, 10 also enables automatic gear shifting, which can be achieved without interruption of the propulsion power. The propulsive power includes momentum gained from the rotating gears and shafts of the DCT 1. Such a shift is similar in design to a mechanical manual shift and it accordingly has very low friction losses. The dual clutch transmission 1 also provides parallel manual shifting that can be used in a transverse arrangement in a front wheel drive vehicle.

The DCT 1 according to the present application may be similarly connected to a known manual transmission, such as a parallel manual transmission. In the known manual transmission, the drive shaft for the front axle of the vehicle extends outwardly from its DCT case, parallel to the output shaft 14 of the main DCT 1. The known manual transmission arrangements leave less space for the actuation of the manual transmission and the clutch, but also for the optional electric motor. An optional electric motor may be used as a starting device for the internal combustion engine, as an energy recovery device for braking operations or as an additional drive structure in a hybrid vehicle. Having such a small space presents a number of difficulties which are solved or at least alleviated by the present application. The present application provides a DCT 1 having two clutches for connecting to an electric motor and a manual transmission in a compact manner.

The present application provides a compact structure of a parallel transmission. The parallel transmission comprises two

input shafts

20, 22, each of which may be non-rotatably coupled to a shaft via its own clutch powered by the vehicle's drive engine. The DCT 1 of the present application also provides an output shaft 14, the output shaft 14 being parallel to the

input shafts

20, 22.

The DCT 1 according to the present application is particularly suitable for a transverse arrangement of a front wheel drive vehicle, wherein, for example, the front differential is positioned below the

pinions

41, 51. A short overall length of the drive train for transmitting torque can be achieved.

The present application provides at least two

smaller pinions

41, 51 on the intermediately

disposed layshafts

40, 50, which are in meshing engagement with one larger output gear 12. The output gear 12 is in turn fixed to an output shaft 14. This arrangement provides a compact and lightweight DCT 1.

The present application also allows for a design in which the output gear 12 is incorporated into the transmission differential arrangement without providing an intermediate output shaft of the DCT 1. This allows for a very compact packaging situation for the DCT 1.

It is also advantageous to provide not only even gears fixed to one output shaft, but also odd gears fixed to the other output shaft. This arrangement provides the above-described shifting operation in a smooth and efficient manner when shifting is performed successively. This is because during an upshift or downshift, the DCT 1 may alternately engage one of the two clutch discs 8, 10. For example, a shift operation from third gear to fourth gear results in the solid input shaft 20 and the hollow input shaft 22 being alternately engaged, which is energy efficient and fast.

Advantageously, some of the idler gears of the lower gears (for example, first, second, third or fourth gears) are provided on the same layshaft 50. In fig. 2, the first-gear idler 60, the second-gear idler 61, the third-gear idler 62, and the fourth-gear idler 63 are mounted on the same lower countershaft 40. Conversely, the idler gearwheel of a high gear (for example five, six or seven gear) is arranged on the other countershaft. According to fig. 2, the fifth gear idler 64, the sixth gear idler 65 and the seventh gear idler 66 are arranged on the same upper layshaft 50. The upper layshaft 40 has a higher rotational speed and a smaller diameter for lower torque transfer than the lower layshaft 50. This arrangement eliminates the need to provide multiple countershafts of larger dimensions to carry respectively those low-range (i.e., first, second, third or fourth) heavy-duty idler gears 60, 61, 62, 63 on the respective multiple shafts. Therefore, the DCT 1 is made light and less costly.

The countershaft bearing 73 of the DCT 1 is adjacent to the pinion gears 41, 51. The layshaft bearing 73 provides greater support for the

layshafts

40, 50 carrying the

pinions

41, 51 to reduce undesirable shaft deflection. Excessive shaft deflection may reduce shift efficiency or cause premature gear wear. Idler shaft bearings 74 near the first reverse gear 35 and the second reverse gear 36 also provide strong support for the reverse idler shaft 38. In the same manner, output shaft bearings 75 at opposite ends of the output shaft 14 provide robust support for the output shaft 14.

In fact, it is also advantageous to provide the first-gear idler 60, the second-gear idler 61 and the reverse idler 37 close to the

bearings

73, 74 for support. As shown in fig. 2, three countershaft bearings 73 abut against the first, second and reverse idler gears 60, 61 and 37, respectively, for providing greater support to the upper and

lower countershafts

40 and 50. The loads experienced by the

pinions

41, 51, and in particular the low (e.g., first and second) gears, are greater than those experienced by the high (e.g., fifth, sixth, and seventh) gears because the gear ratios for low and reverse gears are greater. Thus, the carrier shaft of the lower gear (e.g., lower countershaft 50) must carry a strong driving torque and carry a heavy gear of a larger size. If those loads are taken up by the support bearings close to the shaft, the bending of their load-carrying shafts will be reduced.

FIG. 2 illustrates a torque flow path for the first gear ratio. In fig. 2, the input torque of first gear is received from a crankshaft 2 of an internal combustion engine (not shown). According to fig. 2, the solid input shaft 20 receives input torque for first gear from the dual clutch 6 of the DCT 1. Torque for first gear is transmitted from the solid input shaft 20 to the output shaft 14 via the first gear fixed sheave 24, via the first gear idler 60, via the double-sided coupling 83, via the lower layshaft 50, via the lower pinion 51, and via the output gear 12. The double-sided coupling 83 engages the first-gear idler 60 to the lower layshaft 50 when transmitting first-gear torque (providing first gear of the DCT 1). The number of gear pairs with tooth engagement or meshing for first gear torque transmission is two.

FIG. 3 illustrates a torque flow path for the second gear ratio. In fig. 3, the input torque of the second gear is received from a crankshaft 2 of an internal combustion engine (not shown). According to fig. 3, the hollow input shaft 22 receives input torque for second gear from the double clutch 6 of the DCT 1. Torque for second gear is transmitted from the hollow input shaft 22 to the output shaft 14 via the second fixed gear 30, via the second idler gear 61, via the double-sided coupling device 84, via the lower counter shaft 50, via the lower pinion 51, via the output gear 12. The double-sided coupling 84 engages the second-gear idler 61 to the lower layshaft 50 when transmitting second-gear torque (providing second gear of DCT 1). The number of gear pairs with engaged or meshed teeth for torque transmission in second gear is two.

FIG. 4 illustrates the torque flow path for the third gear ratio. In fig. 4, the input torque of third gear is received from the crankshaft 2 of the internal combustion engine (not shown). According to fig. 4, the solid input shaft 20 receives input torque for third gear from the dual clutch of the DCT 1. Torque for third gear is transmitted from the solid input shaft 20 to the output shaft 14 via the third fixed gear 25, via the third idler gear 62, via the double-sided coupling 83, via the lower layshaft 50, via the lower pinion 51, via the output gear 12. When transmitting third gear torque (providing third gear of DCT 1), the double-sided coupling 83 engages the third idler gear 62 to the lower layshaft 50. The number of gear pairs with tooth engagement or meshing for torque transmission in third gear is two.

FIG. 5 illustrates a torque flow path for the fourth speed ratio. In fig. 5, the input torque of the fourth gear is received from the crankshaft 2 of the internal combustion engine (not shown). According to fig. 5, the hollow input shaft 22 receives an input torque of fourth gear from the double clutch 6 of the DCT 1. Torque of the fourth gear is transmitted from the hollow input shaft 22 to the output shaft 14 via the fourth-gear fixed pulley 31, via the fourth-gear idle pulley 63, via the double-sided coupling device 84, via the lower counter shaft 50, via the lower pinion 51, via the output gear 12. When transmitting fourth gear torque (providing fourth gear of DCT 1), the double-sided coupling 84 engages the fourth-gear idler 63 to the lower layshaft 50. The number of gear pairs with tooth engagement or meshing for the fourth gear torque transmission is two.

FIG. 6 illustrates a torque flow path for the fifth speed ratio. In fig. 6, input torque of fifth gear is received from a crankshaft 2 of an internal combustion engine (not shown). According to fig. 6, the solid input shaft 20 receives input torque for fifth gear from the dual clutch 6 of the DCT 1. Torque for fifth gear is transmitted from the solid input shaft 20, via the fifth fixed gear 26, via the fifth idler gear 64, via the double-sided coupling device 82, via the upper layshaft 40, via the upper pinion 41, via the output gear 12 to the output shaft 14. The double-sided coupling 82 engages the fifth idler 64 to the upper layshaft 40 when transmitting fifth gear torque (providing fifth gear of DCT 1). The number of gear pairs with tooth engagement or mesh for torque transmission in fifth gear is two.

FIG. 7 illustrates the torque flow path for the six speed ratio. In fig. 7, input torque for sixth gear is received from a crankshaft 2 of an internal combustion engine (not shown). According to fig. 7, the hollow input shaft 22 receives input torque for six gears from the dual clutch 6 of the DCT 1. Torque in sixth gear is transmitted from the hollow input shaft 22 to the output shaft 14 via the sixth fixed gear 32, via the sixth idler gear 65, via the double-sided coupling device 81, via the upper countershaft 40, via the upper pinion 41, via the output gear 12. The double-sided coupling 81 engages the six-speed idler 65 to the upper layshaft 40 when transmitting six-speed torque (providing six-speed of the DCT 1). The number of gear pairs with tooth engagement or mesh for torque transmission in sixth gear is two.

FIG. 8 illustrates torque flow paths for the seven speed transmission ratio. In fig. 8, input torque of seven speeds is received from a crankshaft 2 of an internal combustion engine (not shown). According to fig. 8, the solid input shaft 20 receives input torque for seven gears from the dual clutch 6 of the DCT 1. Torque for seven gears is transmitted from the solid input shaft 20, via the seven-gear fixed sheave 27, via the seven-gear idler sheave 66, via the double-sided coupling device 82, via the upper layshaft 40, via the upper pinion 41, via the output gear 12 to the output shaft 14. The double-sided coupling 82 engages the seven-speed idler 66 to the upper layshaft 40 when transmitting seven-speed torque (providing seven-speed of DCT 1). The number of gear pairs with tooth engagement or mesh for seven speed torque transmission is two.

FIG. 9 illustrates the torque flow path for the reverse speed ratio. In fig. 9, the input torque of the reverse gear is received from the crankshaft 2 of the internal combustion engine (not shown). According to fig. 9, the hollow input shaft 22 receives an input torque of a reverse gear from the double clutch 6 of the DCT 1. The torque in reverse is transmitted from the hollow input shaft 22, via the fixed second gear 30, via the first reverse gear 35, via the reverse idler shaft 38, via the second reverse gear 36 and via the reverse idler 37. The torque is then transmitted to the output shaft 14 via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, and via the output gear 12. When a reverse torque is transmitted (providing the reverse of DCT 1), the double-sided coupling 81 engages the reverse idler 37 to the upper layshaft 40. The number of gear pairs with engaged or meshed teeth for reverse torque transmission is three.

Fig. 10 shows an assembly 100 of a double-sided coupling device 102 and its

adjacent gears

101, 103 for engagement. The assembly 100 comprises a shaft 104 with two coaxially mounted

idlers

101, 103 on two bearings respectively. A coupling device 102 is provided between the left idler 101 and the right idler 103. The coupling device 102 is configured to move along the shaft 104 to selectively engage either of the

idlers

101, 103 at a time. In other words, the

idlers

101, 103 may alternately be brought into non-rotational engagement with the shaft 104 via the coupling device 102. Symbols for the display assembly 100 are provided on the right hand side of fig. 10.

Fig. 11 shows an assembly 110 of a single-sided coupling device 112 with its adjacent gear 113 for engagement. The assembly 110 includes a shaft 114 having a coaxially mounted idler pulley 113 on bearings. The coupling device 112 is arranged adjacent to the idler wheel 113 on the left side. The coupling device 112 is configured to move along the shaft 114 to engage or disengage the idler pulley 113. In other words, the idler 113 is brought into non-rotational engagement with the shaft 104 by the single-sided linkage 112. Symbols for the display assembly 110 are provided on the right hand side of fig. 11.

Fig. 12 shows assembly 120 with idler gear 121 rotatably supported by shaft 122 on bearings 123. The idler gear 121 is coaxially mounted to the shaft 122 via a bearing 123. Bearing 123 allows idler gear 121 to rotate freely about shaft 122. The symbols of the display assembly 120 are provided on the right hand side of fig. 12.

Fig. 13 shows an assembly 130 supporting a gear 132 fixed on a shaft 131. A fixed gear 132 is coaxially mounted to the shaft 131 such that the gear 132 is fixed to the shaft 131. The fixed gear 132 and the shaft 131 are coupled as a single body so that the torque of the fixed gear 132 is directly transmitted to the shaft 131, and vice versa.

A plurality of fixed gears are fixedly connected to the

input shafts

20, 22 and the

other shafts

14, 38, 40, 50 in a manner similar to the assembly 130. The reference numerals for such fixed gears in the previous figures are provided on the left side in fig. 13. The more commonly used symbols for such fixed gears are provided on the right hand side of fig. 13.

Fig. 14 shows a cross section through a crankshaft 2 of an internal combustion engine according to an embodiment of the DCT 1. According to fig. 14, the crankshaft 2 of an internal combustion engine, not shown here, is non-rotatably connected to the housing 4 of the double clutch 6. The dual clutch 6 comprises an inner clutch disk 8 and an outer clutch disk 10, which can be non-rotatably engaged with the housing 4 via a control element, which is not shown here. The solid input shaft 20 is non-rotatably connected to the inner clutch disc 8 and extends all the way through the hollow shaft 22. Similarly, the hollow input shaft 22 is non-rotatably connected to the outer clutch plate 10. The inner clutch disc 8 is also known as an inner clutch, and the outer clutch disc 10 is also known as an outer clutch. The

input shafts

20, 22 comprise an end 5 connected to the two clutch discs 8, 10. These ends are also referred to as the clutch disk ends 5 of the input shaft.

The outer diameter around the inner clutch plate 8 is larger than the outer diameter around the outer clutch plate 10. The outer diameter of the inner clutch plate 8 is therefore larger than the outer diameter of the outer clutch plate 10.

The nine torque flow paths described above not only provide a variable scheme to produce the nine gears of the DCT 1, but also provide the possibility of efficiently switching from one gear to another. The gear shift can be achieved by switching between two input shafts, switching between gears in a double-meshed structure, or a combination of both.

For example, the DCT 1 may provide odd-numbered gears (i.e., first, third, fifth, and seventh gears) by driving the gears of the DCT 1 using the solid input shaft 20. The DCT 1 may also provide even-numbered gears (i.e., second, fourth, and sixth gears) by driving the gears of the DCT 1 using the hollow input shaft 22. Gear shifting between odd and even numbers can be obtained by alternating between the two

input shafts

20, 22.

A double engagement structure provides efficient and quick gear shifting between two driven gear stages that mesh with a common drive gear. For example, the DCT 1 provides convenience in selecting fourth gear or sixth gear without stopping their common drive gear (i.e., the fourth fixed gear 31). This selection may be achieved by engaging either driven fourth-speed idler 63 or driven sixth-speed idler 65.

The double meshing structure of the fourth-gear fixed wheel 31 reduces the number of driving gears, which is obtained by the common engagement of the driven fourth-gear idler gear 63 and the driven sixth-gear idler gear 65. For example, the fourth-speed fixed gear 31 and the sixth-speed fixed gear 32 are referred to as a single gear as a drive gear, and are shared by the fourth-speed idler gear 63 and the sixth-speed idler gear 65. Therefore, the number of gears on the hollow input shaft 22 has been reduced, and less space is required on the hollow input shaft 22, whereby the DCT 1 is made lighter and cheaper.

The park lock gear 39 comprises a park lock on the lower layshaft 50 which carries the final drive pinion 51. The parking lock is a wheel provided with a ratchet device having a pawl device with a rack element, a claw or the like. The park lock keeps the lower layshaft 50, lower pinion 51, output gear 12 and output shaft 14 from rotating, which causes the vehicle with the DCT 1 to change from traveling to stopping when the vehicle is parked. The detailed structure of the parking lock is not shown.

A smaller number of gear tooth engagements (i.e., gear engagements) is preferred when providing gear mesh or ratcheting for torque transfer. The smaller number of gear tooth engagements provides lower noise and more efficient torque transfer. Examples of fewer gear tooth engagements are provided in fig. 2-9.

The DCT 1 drives the first and reverse gear sets through

different input shafts

20, 22. A vehicle having a DCT 1 can be moved between a slow forward mode and a slow reverse mode by engaging and not engaging respective clutch discs 8, 10, which are connected to two

input shafts

20, 22, respectively. The DCT 1 causes the vehicle to move forward and backward quickly with less loss to transmit power or gear momentum. This strategy contributes to many situations where the wheels of the vehicle are trapped in a harsh environment, such as a snow or mud pit. The vehicle can then be swung out freely merely by switching between the two clutch disks 8, 10.

Fig. 15-16 illustrate another embodiment of the present application. This embodiment includes similar components to those of the previous embodiments. Similar parts are marked with the same or similar reference numerals. Descriptions relating to similar components are incorporated herein by reference.

FIG. 15 illustrates a front view of the transmission of the present application. The relatively large output gear 12 on the output shaft 14 meshes with a lower pinion 51 provided on the lower layshaft 50. The output gear 12 also meshes with an upper pinion 41 provided on the upper layshaft 40. The reverse idler shaft 38, solid input shaft 20 and hollow output shaft 22 are disposed in parallel with the

countershafts

40, 50. In some variants of the present application, at least one other layshaft with other pinions may be provided, but this is not shown. Such other pinion gears may then also mesh or mesh with the output gear 12.

Fig. 15 also includes a cut plane a-a for showing a cross-section through the gearbox, which is shown in fig. 16. For embodiments with more than two secondary shafts or additional idler shafts, cutting planes leading through all shafts are similarly used. One of the objectives of FIG. 16 is to further illustrate the structure and torque flow through the transmission embodiment.

Fig. 16 shows a simplified cross-sectional view through the double-clutch gearbox 1 of fig. 15. The structure and the respective torque flows for a plurality of gears of the double-clutch gearbox 1 are shown.

The dual clutch transmission 1 includes, from top to bottom, an output shaft 14, an upper layshaft 40, a hollow shaft 22, a solid input shaft 20, a lower layshaft 50, and a reverse idler shaft 38.

The shafts are arranged in the gearbox 1 parallel to each other at a predetermined mutual distance. A hollow shaft 22 is concentrically disposed about the solid shaft 20. The solid input shaft 20 protrudes out of the hollow input shaft 22 at both ends.

The solid input shaft 20 includes, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, a third-gear fixed gear 25, a fifth-gear fixed gear 26, a first-gear fixed gear 24, a seventh-gear fixed gear 27, and a solid shaft bearing 71. The hollow shaft bearing 72 also serves as the solid shaft bearing 71.

The hollow input shaft 22 includes, from the right end to the left end, a hollow shaft bearing 72, a second-speed fixed wheel 30, a fourth-speed fixed wheel 31 (which also functions as a sixth-speed fixed wheel 32), and a hollow shaft bearing 72 (which also functions as a solid shaft bearing 71).

The upper layshaft 40 includes, from right to left end, an upper pinion 41, a layshaft bearing 73, a second-speed idler 61, a double-sided coupling device 80, a fifth-speed idler 64, a third-speed idler 62, a double-sided connecting device 81, a first-speed idler 60, and a layshaft bearing 73. The second-speed idler 61 is engaged with the second-speed idler 30. The fifth-gear idler 64 meshes with the fourth-gear fixed wheel 31. The third idler gear 62 meshes with the third fixed gear 25. The first-speed idler 60 meshes with the first-speed fixed wheel 24. The double-sided coupling device 80 is configured to move along the upper countershaft 40 to engage the attached second-gear idler 61 or fifth-gear idler 64 to the upper countershaft 40. The double-sided coupling 81 is also configured to move along the upper layshaft 40 to engage the third-gear idler 62 or the first-gear idler 60 to the upper layshaft 40.

The lower countershaft 50 includes, from right to left end, a lower pinion 51, a countershaft bearing 73, a reverse idler 37, a double-sided coupling 83, a six-speed idler 65, a park lock gear 39, a five-speed idler 64, a double-sided coupling 82, a seven-speed idler 66, and a countershaft bearing 73. The sixth idler 65 meshes with the sixth fixed sheave 32. The fifth idler gear 64 meshes with the fifth fixed gear 26. The seventh-speed idler 66 meshes with the seventh-speed fixed pulley 27. The double-sided coupling device 83 is configured to move along the lower countershaft 50 to engage the reverse idler 37 or the six-speed idler 65 to the lower countershaft 50. The double-sided coupling 82 is also configured to move along the lower countershaft 50 to engage either the fifth-speed idler 64 or the seventh-speed idler 66 to the lower countershaft 50.

The reverse idler shaft 38 includes, from the right end to the left end, an idler shaft bearing 74, a first reverse gear 35, a second reverse gear 36, and an idler shaft bearing 74. The first reverse gear 35 is engaged with the second fixed gear 30. The second reverse gear 36 is meshed with a reverse idler gear 37.

Fig. 16 also shows the clutch housing 4 which surrounds the gears of the dual clutch transmission 1. The clutch housing 4 comprises a plurality of

walls

3, 6 which are located next to the gears of the dual clutch transmission 1. In particular, the side wall 6 of the clutch housing 4 is positioned close to the first-gear idler gear 60 at one end of the upper layshaft 40. The first-gear idler gear 60 is located on an end opposite to the end of the upper layshaft 40 to which the upper pinion 41 is fixed.

In fig. 16, a seven-speed idler 66 is mounted on the left end of the lower layshaft 50, opposite the end carrying the lower pinion 51. The seventh-speed idler 66 has the smallest diameter compared to the

idlers

60, 61, 62, 63, 64, 65 of the other gears. Arranging the seven-gear idler gear at this end brings the side wall 3 closer to the lower layshaft 50 than if the idler gears of the other gears were arranged at this

end

60, 61, 62, 63, 64, 65.

Therefore, in order to make the dual clutch transmission 1 more compact, it is advantageous to mount the idlers of different gears on the layshaft one after the other from the low gear to the high gear, starting from the end of the layshaft with the pinion to the distal end of the layshaft. Furthermore, it is also advantageous to mount fixed wheels of different gears on the

input shafts

20, 22 one after the other from high to low, starting from the end of the

input shafts

20, 22 intended to be connected to the crankshaft 2. The high range fixed gear is larger than the low range fixed gear on the

input shafts

20, 22.

The torque flow according to first gear of fig. 16 starts from the solid input shaft 22, via the first gear fixed gearwheel 24, via the first gear idler gearwheel 60, via the double-sided coupling device 81, via the upper countershaft 40, via the upper pinion 41, via the output gear wheel 12 to the output shaft 14.

The torque flow according to second gear of fig. 16 starts from the hollow input shaft 22, via the fixed gear 30, via the idler gear 61, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gear 12 to the output shaft 14.

The torque flow according to third gear of fig. 16 is from the solid input shaft 20, via the third fixed gear 25, via the third idler gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gear 12 to the output shaft 14.

The torque flow according to the fourth gear of fig. 16 starts from the hollow input shaft 22, via the fourth-gear fixed gearwheel 31, via the fourth-gear idle gearwheel 63, via the double-sided coupling 80, via the upper countershaft 40, via the upper pinion 41, via the output gear 12 to the output shaft 14.

The torque flow according to fifth gear of fig. 16 starts from the solid input shaft 20, via the fifth fixed gearwheel 26, via the fifth idler gearwheel 64, via the double-sided coupling 82, via the lower layshaft 50, via the lower pinion 51, via the output gear 12 to the output shaft 14.

The torque flow according to sixth gear of fig. 16 starts from the hollow input shaft 22, via the sixth fixed gear 32, via the sixth idler 65, via the double-sided coupling 83, via the lower layshaft 50, via the lower pinion 51, via the output gear 12 to the output shaft 14.

The torque flow according to the seventh gear of fig. 16 starts from the solid input shaft 20, via the seventh fixed gear 27, via the seventh idler 66, via the double-sided coupling 82, via the lower layshaft 50, via the lower pinion 51, via the output gear 12 to the output shaft 14.

The torque flow according to the reverse gear of fig. 16 starts from the neutral input shaft 22 via the fixed gear wheel 30, via the first reverse gear wheel 35, via the reverse idler shaft 38, via the second reverse gear wheel 36 and via the reverse idler wheel 37. The torque then goes to the output shaft 14 via the double-sided coupling 83, via the lower layshaft 50, via the lower pinion 51 and via the output gear 12.

Fig. 17-18 illustrate another embodiment of the present application. This embodiment includes similar components to those of the previous embodiments. Similar parts are marked with the same or similar reference numerals. Descriptions relating to similar components are incorporated herein by reference.

FIG. 17 illustrates a front view of the transmission of the present application. The relatively large output gear 12 on the output shaft 14 meshes with a lower pinion 51 provided on the lower layshaft 50. The output gear 12 also meshes with an upper pinion 41 provided on the upper layshaft 40. The reverse idler shaft 38, solid input shaft 20 and hollow output shaft 22 are disposed in parallel with the

countershafts

Fig. 17 also includes a cut plane a-a for showing a cross-section through the gearbox, which is shown in fig. 18. For embodiments with more than two secondary shafts or additional idler shafts, cutting planes leading through all shafts are similarly used. One of the objectives of FIG. 18 is to further illustrate the structure and torque flow through the transmission embodiment.

Fig. 18 shows a simplified cross-sectional view through the double-clutch gearbox 1 of fig. 17. The structure and the respective torque flows for a plurality of gears of the double-clutch gearbox 1 are shown.

The solid input shaft 20 includes, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72 (which also serves as the solid shaft bearing 71), a third-speed fixed gear 25, a fifth-speed fixed gear 26, a seventh-speed fixed gear 27, a first-speed fixed gear 24, and the solid shaft bearing 71.

The upper layshaft 40 includes, from right to left end, an upper pinion 41, a layshaft bearing 73, a second-speed idler 61, a double-sided coupling device 80, a fifth-speed idler 64, a third-speed idler 62, a double-sided connecting device 81, a first-speed idler 60, and a layshaft bearing 73. The second-speed idler 61 is engaged with the second-speed fixed wheel 30. The fifth-gear idler 64 meshes with the fourth-gear fixed wheel 31. The third idler gear 62 meshes with the third fixed gear 25. The first-gear idle wheel 60 is meshed with the first-gear fixed wheel 2. The double-sided coupling device 80 is configured to move along the upper countershaft 40 to engage the attached second-gear idler 61 or fifth-gear idler 64 to the upper countershaft 40. The double-sided coupling 81 is also configured to move along the upper layshaft 40 to engage the third-gear idler 62 or the first-gear idler 60 to the upper layshaft 40.

The reverse idler shaft 38 includes, from the right end to the left end, an idler shaft bearing 74, a first reverse gear 35, a second reverse gear 36, and an idler shaft bearing 74. The first reverse gear 35 is engaged with the second fixed gear 30. The second reverse fixed gear 36 is engaged with a reverse idle gear 37.

Fig. 18 also shows the clutch housing 4 which surrounds the gears of the dual clutch transmission 1. The clutch housing 4 comprises a plurality of walls 3, 7 which are located next to the gears of the dual clutch transmission 1. In particular, the side wall 7 of the clutch housing 4 is positioned close to the first-gear idler gear 60 at one end of the upper layshaft 40. The first-gear idler gear 60 is located on an end opposite to the end of the upper layshaft 40 to which the upper pinion 41 is fixed.

Compared to the clutch housing 4 of fig. 16, the side wall 6 of fig. 16 is closer to the upper countershaft 40 than the side wall 7 of fig. 18. This is because the first-speed fixed gear 24 is on the left side of the seventh-speed fixed gear 27. The largest seven-speed idler 60 forces the side wall 7 further away from the upper layshaft 40. In short, the clutch housing 4 of fig. 16 is more compact than the clutch housing of fig. 18.

The torque flow paths for the embodiment of fig. 17-18 for seven forward gears and one reverse gear are similar to those of fig. 15-16.

While the above description contains many specifics, these should not be construed as limiting the scope of the embodiments, but merely as illustrating possible embodiments. In particular, the above advantages of the present embodiments should not be viewed as limiting the scope of the embodiments, but merely as explaining potential advantages if the embodiments are used in practice. Thus, the scope of the present embodiments should be determined by the claims rather than by the examples given.

Claims

1. A dual clutch transmission (1) comprising:

-an inner input shaft (20) and an outer input shaft (22), at least a portion of the inner input shaft (20) being surrounded by the outer input shaft (22),

-a first clutch disc (8) connected to the inner input shaft (20) and a second clutch disc (10) connected to the outer input shaft (22),

a first countershaft (40), a second countershaft (50) and a third countershaft (38) spaced apart from the input shafts (20, 22) and arranged parallel to the input shafts (20, 22),

at least one of the secondary shafts (38, 40, 50) comprises a pinion (41, 51),

-gears arranged on the first countershaft (40), the second countershaft (50), the third countershaft (38), the inner input shaft (20) and the outer input shaft (22), including a first gear set, a second gear set, a third gear set, a fourth gear set, a fifth gear set, a sixth gear set and a seventh gear set for providing seven incremental forward gears,

-the first gear set comprises a first fixed gear (24) on the inner input shaft (20) meshing with a first gear idler gear (60) on one of the layshafts (38, 40, 50) for providing a first forward gear,

-the third gear set comprises a third fixed gear (25) on the inner input shaft (20) meshing with a third gear idler gear (62) on one of the layshafts (38, 40, 50) for providing a third forward gear,

-the fifth gear set comprises a fifth fixed gear (26) on the inner input shaft (20) meshing with a fifth gear idler gear (64) on one of the layshafts (38, 40, 50) for providing a fifth forward gear,

-the seventh gear set comprises a seventh fixed gear (27) on the inner input shaft (20) meshing with a seventh gear idler gear (66) on one of the layshafts (38, 40, 50) for providing a seventh forward gear,

-the second gear set comprises a second fixed gear (30) on the outer input shaft (22) meshing with a second gear idler gear (61) on one of the layshafts (38, 40, 50) for providing a second forward gear,

-the fourth gear set comprises a fourth fixed gear (31) on the outer input shaft (22) meshing with a fourth gear idler gear (63) on one of the layshafts (38, 40, 50) for providing a fourth forward gear,

-the sixth gear set comprises a sixth fixed gear (32) on the outer input shaft (22) meshing with a sixth gear idler gear (65) on one of the layshafts (38, 40, 50) for providing a sixth forward gear, and

-each gear set comprises a coupling device arranged on one of the layshafts (38, 40, 50) to selectively engage one of the gears for selecting one of seven gears, and

-the fourth fixed gearwheel (31) also meshes with a sixth gear idler gearwheel (65),

wherein,

the dual clutch transmission (1) further comprises a park-lock gear (39) fixed to one of the layshafts (38, 40, 50) carrying the final drive (41, 51).

2. Double-clutch transmission (1) according to claim 1, wherein

One of the lower-range fixed gearwheel (24, 25, 26, 27, 30, 31, 32) is closer to the clutch disk end (5) of the input shaft (20, 22) than the other higher-range fixed gearwheel (24, 25, 26, 27, 30, 31, 32).

3. Double-clutch transmission (1) according to one of the preceding claims, wherein

One of the lower idler gears (60, 61, 62, 63, 64, 65, 66) is closer to the pinion (41, 51) than the other higher idler gear (60, 61, 62, 63, 64, 65, 66) on their common layshaft (20, 22).

4. Double-clutch transmission (1) according to one of the preceding claims, wherein

The first forward and reverse gears are provided by different input shafts (20, 22).

5. Double-clutch transmission (1) according to one of the preceding claims, wherein

-the gear wheels further comprise a reverse gear set comprising a reverse fixed gear wheel (30) on one of the input shafts (20, 22) meshing with a first reverse gear wheel (35) on a third layshaft (38) for receiving an input reverse torque;

-the reverse gear set further comprises a second reverse gear wheel (36) on the third layshaft (38) meshing with one of the idler gears (37) on one of the first layshaft (40) and the second layshaft (50) for outputting the received reverse torque to the pinion (41, 51); and

-the reverse gear set further comprises a coupling device (81) on one of the layshafts (38, 40, 50) to engage a gear (37) of reverse gear for selecting reverse gear.

6. Double-clutch transmission (1) according to one of the preceding claims, further comprising two pinions (41, 51) mounted on two of the layshafts (38, 39, 40, 50), respectively.

7. Double-clutch transmission (1) according to one of the preceding claims, wherein

At least two of the first gear idler gear (60), the second gear idler gear (61), the third gear idler gear (62) and the fourth gear idler gear (63) are mounted on the same countershaft (38, 40, 50).

8. Double-clutch transmission (1) according to one of the preceding claims, wherein

At least two of the fifth gear idler gear (64), the sixth gear idler gear (65) and the seventh gear idler gear (66) are mounted on the same layshaft (38, 40, 50).

9. Double-clutch transmission (1) according to one of the preceding claims, further comprising

Bearings (71, 72, 73, 74, 75) for supporting the layshafts (38, 40, 50), at least one of the bearings being disposed proximate the pinion (41, 51).

10. Double-clutch transmission (1) according to claim 8, wherein

At least one bearing (74) is disposed proximate to one of the low range driven gear (60, 61, 62) and the reverse range driven gear (35, 36, 37).

11. Gearbox with a dual clutch transmission (1) according to one of the preceding claims, comprising

An output gear (12) on the output shaft (14), the output gear (12) meshing with the pinion (41, 51) for outputting a driving torque to the torque output member.

12. A drive train device having a gearbox according to claim 11, comprising

At least one power source for generating a drive torque.

13. The driveline device of claim 12, wherein the power source comprises an internal combustion engine.

14. The power train device according to claim 12,

the power source includes an electric motor.

15. A vehicle comprising a driveline arrangement according to one of claims 12 to 14.