Double-clutch Transmission For Vehicles

Abstract

A double-clutch transmission includes, but is not limited to an inner input shaft and an outer input shaft that are connected to a first clutch and a second clutch respectively. A first layshaft and a second layshaft of the DCT are spaced apart and arranged in parallel to the input shafts. Gearwheels of the DCT are arranged on the first layshaft, on the second layshaft, on the inner input shaft and on the outer input shaft. The gearwheels include, but are not limited to seven gearwheel groups for providing seven sequentially increasing gears. Each of the gearwheel groups includes, but is not limited to a fixed gearwheel on one of the input shafts that meshes with an idler gearwheel on one of the layshafts. A fourth fixed gearwheel meshes with a fourth gear idler gearwheel and a sixth gear idler gearwheel. A third fixed gearwheel meshes with a third gear idler gearwheel and a fifth gear idler gearwheel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a U.S. National-Stage entry under 35 U.S.C. .sctn.371 based on International Application No. PCT/EP2009/002304, filed Mar. 31, 2009, which was published under PCT Article 21(2) and which claims priority to European Application No. 08006645.9, filed Mar. 31, 2008, and which claims priority to European Application No. 08006638.4, filed Mar. 31, 2008, and which claims priority to European Application No. 08006639.2, filed Mar. 31, 2008, and which claims priority to European Application No. 08006640.0, filed Mar. 31, 2008, and which claims priority to European Application No. 08006641.8, filed Mar. 31, 2008, and which claims priority to European Application No. 08006642.6, filed Mar. 31, 2008, and which claims priority to European Application No. 08006635.0, filed Mar. 31, 2008, and which claims priority to European Application No. 08006643.4, filed Mar. 31, 2008, and which claims priority to European Application No. 08006644.2, filed Mar. 31, 2008, and which claims priority to European Application No. 08006486.8, filed Mar. 31, 2008, and which claims priority to European Application No. 08006606.1, filed Mar. 31, 2008, and which claims priority to European Application No. 08006607.9, filed Mar. 31, 2008, and which claims priority to European Application No. 08006608.7, filed Mar. 31, 2008, and which claims priority to European Application No. 08006646.7, filed Mar. 31, 2008, and which claims priority to European Application No. 08006616.7, filed Mar. 31, 2008, and which claims priority to European Application No. 08006617.8, filed Mar. 31, 2008, and which claims priority to European Application No. 08006609.5, filed Mar. 31, 2008, and which claims priority to European Application No. 08006610.3, filed Mar. 31, 2008, and which claims priority to European Application No. 08006611.1, filed Mar. 31, 2008, and which claims priority to European Application No. 08006612.9, filed Mar. 31, 2008, and which claims priority to European Application No. 08006621.0, filed Mar. 31, 2008, and which claims priority to European Application No. 08006622.8, filed Mar. 31, 2008, and which claims priority to European Application No. 08006623.6, filed Mar. 31, 2008, and which claims priority to European Application No. 08006624.4, filed Mar. 31, 2008, and which claims priority to European Application No. 08006569.1, filed Mar. 31, 2008, and which claims priority to European Application No. 08006637.6, filed Mar. 31, 2008, and which claims priority to European Application No. 08006615.2, filed Mar. 31, 2008, and which claims priority to European Application No. 08006636.8, filed Mar. 31, 2008, and which claims priority to European Application No. 08006625.1, filed Mar. 31, 2008, and which claims priority to European Application No. 08006626.9, filed Mar. 31, 2008, and which claims priority to European Application No. 08006627.7, filed Mar. 31, 2008, and which claims priority to European Application No. 08006628.5, filed Mar. 31, 2008, and which claims priority to European Application No. 08006629.3, filed Mar. 31, 2008, and which claims priority to European Application No. 08006630.1, filed Mar. 31, 2008, and which claims priority to European Application No. 08006631.9, filed Mar. 31, 2008, and which claims priority to European Application No. 08006619.4, filed Mar. 31, 2008, and which claims priority to European Application No. 08006620.2, filed Mar. 31, 2008, and which claims priority to European Application No. 08006618.6, filed Mar. 31, 2008, and which claims priority to European Application No. 08006614.5, filed Mar. 31, 2008, and which claims priority to European Application No. 08006613.7, filed Mar. 31, 2008, and which claims priority to European Application No. 08006634.3, filed Mar. 31, 2008, and which claims priority to European Application No. 08006633.5, filed Mar. 31, 2008, and which claims priority to European Application No. 08006632.7, filed Mar. 31, 2008, and which claims priority to European Application No. 08006649.1, filed Mar. 31, 2008, and which claims priority to European Application No. 08006648.3, filed Mar. 31, 2008, and which claims priority to European Application No. 08006647.5, filed Mar. 31, 2008, which are all hereby incorporated in their entirety by reference.

TECHNICAL FIELD

[0002] The present application relates to a double-clutch transmission for vehicles.

BACKGROUND

[0003] The double-clutch transmission (DCT) comprises two input shafts that are connected to two clutches separately for providing driving torques. The two input shafts are also actuated by the two clutches. The two clutches are often combined into a single device that permits actuating any of the two clutches at a time.

[0004] Volkswagen has provided a 7-speed dual clutch gearbox (DSG.RTM.), namely DQ200. The DSG.RTM. DQ200 provides an attempt of having a 7-speed dual clutch gearbox in the cars for street driving.

[0005] The DCT has not yet been widely used in cars for street driving. Problems that hinder the application of DCT for street driving comprise of providing a compact, reliable and fuel-efficient DCT. Therefore, there exists a need for providing such a DCT that is also affordable by consumers.

SUMMARY

[0006] The application provides a double-clutch transmission with an inner input shaft and an outer input shaft. The inner input shaft can be hollow or solid. A portion of the inner input shaft is surrounded by the outer input shaft in a radial direction. The radial direction of a shaft indicates a direction pointing away from a central axis of the shaft following a radius of the shaft.

[0007] There is provided a first clutch and a second clutch which are non-rotatably connected to the inner input shaft and to the outer input shaft respectively. For example, the first clutch is fixed to the inner input shaft and the second the clutch is fixed to the outer input shaft. Alternatively, the non-rotatable connection can be provided by a universal joint.

[0008] The transmission further comprises a first layshaft and a second layshaft that are both radially spaced apart from the input shafts. The first layshaft and the second layshaft are essentially parallel to the input shafts.

[0009] Gearwheels are arranged on the first layshaft, on the second layshaft, on the inner input shaft and on the outer input shaft. A gearwheel can be a fixed wheel or an idler. The gearwheels comprise a first gearwheel group, a second gearwheel group, a third gearwheel group, a fourth gearwheel group, a fifth gearwheel group, a sixth gearwheel group and a seventh gearwheel group for providing seven sequentially increasing forward gear output speeds, which are inverse to their gear ratios. The increasing gears describe an escalating order that members of the order follow each other. Gear ratios of a car according to the application are arranged in a sequentially decreasing manner, which is in an inverse order of gear output speeds. For example, in a vehicle having a transmission, a first gear has the ratio of 3:1, a second gear has the ratio of 2:1, a third gear has the ratio of 1.45:1, a fourth gear has the ratio of 1:1, a fifth gear has the ratio of 0.9:1, a sixth gear ratio has the ratio of 0.7:1 and a seventh gear has the ratio of 0.55:1. The seven gears provide an increasing order of output speed of the transmission for driving the vehicle.

[0010] The first gearwheel group comprises a first fixed gearwheel on the inner input shaft, meshing with a first gear idler gearwheel on one of the layshafts. The third gearwheel group comprising a third fixed gearwheel on the inner input shaft, meshing with a third gear idler gearwheel on one of the layshafts. The fifth gearwheel group comprising a fifth fixed gearwheel on the inner input shaft, meshing with a fifth gear idler gearwheel on one of the layshafts. The seventh gearwheel group comprising a seventh fixed gearwheel on the inner input shaft, meshing with a seventh gear idler gearwheel on one of the layshafts. The second gearwheel group comprising a second fixed gearwheel on the outer input shafts, meshing with a second gear idler gearwheel on one of the layshafts. The fourth gearwheel group comprising a fourth fixed gearwheel on the outer input shafts, meshing with a fourth gear idler gearwheel on one of the layshafts. The sixth gearwheel group comprising a sixth fixed gearwheel on the outer input shafts, meshing with a sixth gear idler gearwheel on one of the layshafts. Each one of the gearwheel groups comprises a coupling device, which is arranged on one of the layshafts to selectively engage one of the idler gearwheels for selecting one of the seven gear ratios.

[0011] The fourth fixed gearwheel on the outer input shaft meshes with the fourth gear idler gearwheel and the sixth gear idler gearwheel. The third fixed gearwheel on the inner input shaft meshes with the third gear idler gearwheel and the fifth gear idler gearwheel.

[0012] The double-clutch transmission provides seven forward gear ratios through the double-clutch. The double-clutch enables gear ratio switching between odd and even ratios to be swift and efficient because the gearwheels for the odd gear ratio and even gear ratio are distributed to different clutches respectively. Two double-meshing features are provided by the third and fourth fixed gearwheels respectively. A first double meshing feature comprises that the third fixed gearwheel meshes with both the third gear idler gearwheel and the fifth gear idler gearwheel. A second double-meshing feature comprises that the fourth fixed gearwheel meshes with both the fourth gear idler gearwheel and the sixth gear idler gearwheel. These two double-meshing features make the double-clutch transmission to be compact, lightweight at low cost because fixed gearwheels are avoided on the input shafts. Furthermore, since the two double-meshing features are provided on the inner input shaft and the outer input shaft respectively, gear ratio jumping between the idler gearwheels of these double-meshing features can be performed efficiently by engaging any of the input shafts using the double clutch.

[0013] The double clutch transmission can provide two coupling devices that engage two of the idler gearwheels of the seven gears respectively at the same time. The process of multiple engagements of the two idler gearwheels on different layshafts is known as pre-selection of gears. Especially, the two idlers of two consecutive gears that are driven by different input shafts of the DCT can be both engaged for shifting from one of the two gears to the other. For example, idler gearwheels of the third gear and the fourth gear of the DCT are both engaged to their weight-carrying layshaft by their neighboring coupling devices when only one of the input shafts receives an input torque. Since incoming torque from any of the input shafts is constantly delivered to an idler gearwheel of the two consecutive gears, there is little or no interruption in torque flow during the gearshift. Therefore, the double-clutch transmission provides continuous and more efficient torque transmission, as compared to the gearshift process in Manual Transmissions.

[0014] According to the application, the DCT may further comprise a reverse gear idler shaft and a reverse gearwheel mounted on the reverse gear idler shaft, the reverse gearwheel meshing with one of the gearwheels on one of the layshafts for providing a reverse gear ratio. The reverse gear ratio is useful for maneuvering the vehicle, such as for parking

[0015] In the application, the first gear ratio and the reverse gear ratio may be provided by different input shafts respectively. If the first forward gear and the reverse gear are provided on two different input shafts, the double clutches of the DCT can enable efficient switching between the two input shafts. As a result, a driving scheme that the DCT engages the two input shafts alternatively can drive the vehicle back and forth rapidly. This scheme is useful for moving the vehicle out of a muddy puddle because the vehicle can simply be driven back and forth to get out the puddle without a time-consuming switching of the gears of the transmission. An embodiment of the application provides that the first gear ratio is driven by the inner input shaft and the reverse gear ratio is driven by the outer input shaft. Some other embodiments of the application provide that the first gear ratio and the reverse gear ratio are both driven by the inner input shaft.

[0016] In the application, the DCT may comprise another reverse gearwheel on the reverse gear idler shaft, the two or more reverse gearwheels meshing with two of the gearwheels respectively.

[0017] According to the application, the double-clutch transmission device may further comprise a reverse pinion mounted on the reverse gear idler shaft. The reverse pinion provides direct torque transmission to a fixed output gearwheel with less loss in torque transmission.

[0018] The double-clutch transmission can further comprise a park-lock gearwheel that is fixed onto one of the layshafts for providing a park-lock. The layshaft with the park-lock comprises a final drive pinion for locking a differential of the DCT. The differential comprises the output gearwheel on the output shaft. The park-lock enables the vehicle to park at a place in a secure manner, even on a slope. The park-lock is easy to implement and beneficial for vehicle and passengers' safety.

[0019] The DCT can have a distance between one of the layshafts with idler gearwheels of low gear ratios (e.g. 1st, 2nd, 3rd gears) and the inner input shaft is greater than a distance between another one of the layshafts with the idler gearwheels of high gear ratios (e.g. 5th, 6th, 7th gears) and the inner input shaft. Idler gearwheels of high gears are smaller than that of the low gears so that the layshaft with idler gearwheels of high gears can be brought closer to the inner input shaft for making the DCT more compact. The distance is measured between longitudinal axes of the shafts.

[0020] In the application, two or more the first gear idler gearwheel, the second gear idler gearwheel, the third gear idler gearwheel and the fourth gear idler gearwheel may be mounted on the same layshaft. Gearwheels of high gear ratios (e.g. 2nd, 3rd & 4th gears) are desired to be installed on the same shaft because the shaft can be made thick so that the other layshaft with gearwheels of lower gear ratios can be made slim at low cost.

[0021] In the application, the first gear idler gearwheel, the second gear idler gearwheel, the third gear idler gearwheel and the fourth gear idler gearwheel may be mounted on the same layshaft.

[0022] In the application, two or more of the fifth gear idler gearwheel, the sixth gear idler gearwheel and the seventh gear idler gearwheel may be mounted on the same layshaft. Gearwheels of high gears (e.g. 5th, 6th & 7th gears) are desired to be installed on the same shaft because the shaft can be made slim for the reduction of cost and size of the double-clutch transmission.

[0023] In the application, the fifth gear idler gearwheel, the sixth gear idler gearwheel and the seventh gear idler gearwheel may be mounted on the same layshaft.

[0024] In the application, the first gear idler gearwheel, the second gear idler gearwheel, the third gear idler gearwheel and the fourth gear idler gearwheel may be mounted on one of the layshafts. The fifth gear idler gearwheel, the sixth gear idler gearwheel and the seventh gear idler gearwheel may be mounted on the other layshaft. Idler gearwheels of high and low gear ratios are separated into two groups that are mounted on different layshafts. This arrangement enables one of the layshaft that carries idler gearwheels of high gear ratio (e.g. 5th, 6th & 7th) to be made slim for reducing weight, size and cost. The other layshaft that carries the idler gearwheels of low gear ratios (e.g. 1st, 2nd, 3rd & 4th) is better used for its larger size to carry more idler gearwheels of heavy duty.

[0025] According to the application, the DCT may further comprise bearings for supporting the layshafts, two or more of the bearings being provided next to the first gear idler gearwheel and the second gear idler gearwheel respectively. The bearings that support a shaft are more advantageously provided next to gearwheels of low gear ratios. The supporting shaft can be made slim and have less deflection when the bearings are next to the gearwheels of low gear ratios.

[0026] In the application, the third and the fifth gearwheel groups may be driven by the inner input shaft, and the fourth and sixth gearwheel groups may be driven by the outer input shaft. Any gear ratio change between the two input shafts can be easily achieved by connecting any of the two input shafts. For example, gear ratio can jump from the third gear to any of the fourth or sixth gear efficiently.

[0027] In the application, the third gear idler gearwheel and the fourth gear idler gearwheel may be provided between the first gear idler gearwheel and the second gear idler gearwheel. Idler gearwheels of the lowest gear ratios are provided at opposite ends of their supporting layshaft so that these idler gearwheels of the heaviest duty are supported by bearings immediately adjacent to them respectively. The supporting layshaft can be reduced in size, cost and weight.

[0028] In the application, there may be further provided two or more pinions that are mounted on the two layshafts respectively, each of the two pinions being next to a bearing for supporting. The pinions transmit torques for driving the vehicle. Bearings that are next to the pinions give strong support to the layshafts that carry the pinions. Consequently, the layshafts can be minimized in size for reducing cost and weight of the DCT.

[0029] In the application, there may be further provided an output gearwheel that meshes with the two pinions on the layshafts for providing an output torque. The output gearwheels receive driving torques from pinions and offer a single output to the exterior of the double-clutch transmission. No multiple external connections that are associated to the layshafts are required. Connection to the double-clutch transmission is thus made simple.

[0030] The output gearwheel provides drive torque to a torque drain such as a differential gear box of a vehicle. Examples of the vehicle include a car or a motorcycle. The pinions of the DCT comb with an output gearwheel respectively such that the output gearwheel transmits torques from the pinions to an output shaft for driving the vehicle.

[0031] The application may provide a power train device with the gearbox. The power train device may comprise one or more power source for generating a driving torque. The power train device is alternatively known as power train.

[0032] In the application, the power source may comprise a combustion engine. The vehicle having the combustion engine and the double-clutch transmission is easy to manufacture. The combustion engine can consume less petrol for environmental protection. Furthermore, a combustion engine for other types of fuel can have even less polluting emission, such as hydrogen fuel.

[0033] In the application, the power source may comprise an electric motor. Electric motor used in as hybrid car, or in an electrical car enables reduction of pollution, as compared to typical combustion using petrol. The electric motor can even recuperate brake energy in a generator mode.

[0034] In the application, there is also provided a vehicle that may comprise a power train device. The vehicle having the power train device is efficient in energy usage by using the double-clutch transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and

[0036] FIG. 1 illustrates a front view of a first embodiment of a double clutch transmission of the application;

[0037] FIG. 2 illustrates the path of torque flow of a first gear transmission ratio;

[0038] FIG. 3 illustrates the path of torque flow of a second gear transmission ratio;

[0039] FIG. 4 illustrates the path of torque flow of a third gear transmission ratio;

[0040] FIG. 5 illustrates the path of torque flow of a fourth gear transmission ratio;

[0041] FIG. 6 illustrates the path of torque flow of a fifth gear transmission ratio;

[0042] FIG. 7 illustrates the path of torque flow of a sixth gear transmission ratio;

[0043] FIG. 8 illustrates the path of torque flow of a seventh gear transmission ratio;

[0044] FIG. 9 illustrates the path of torque flow of a reverse gear transmission ratio;

[0045] FIG. 10 illustrates an assembly of a double-sided coupling device with its neighboring gearwheels for engagement;

[0046] FIG. 11 illustrates an assembly of a single-sided coupling device with its neighboring gearwheel for engagement;

[0047] FIG. 12 illustrates an assembly of an idler gearwheel that is rotatably supported by a shaft on a bearing;

[0048] FIG. 13 illustrates an assembly of a fixed gearwheel that is supported on a shaft;

[0049] FIG. 14 illustrates a cross-section through a crankshaft of an internal combustion engine according to embodiment of the DCT;

[0050] FIG. 15 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0051] FIG. 16 illustrates an expanded side view of the double clutch transmission of FIG. 15;

[0052] FIG. 17 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0053] FIG. 18 illustrates an expanded side view of the double clutch transmission of FIG. 17;

[0054] FIG. 19 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0055] FIG. 20 illustrates an expanded side view of the double clutch transmission of FIG. 19;

[0056] FIG. 21 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0057] FIG. 22 illustrates an expanded side view of the double clutch transmission of FIG. 21;

[0058] FIG. 23 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0059] FIG. 24 illustrates an expanded side view of the double clutch transmission of FIG. 23;

[0060] FIG. 25 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0061] FIG. 26 illustrates an expanded side view of the double clutch transmission of FIG. 25;

[0062] FIG. 27 illustrates a front view of a further embodiment of a double clutch transmission of the application;

[0063] FIG. 28 illustrates an expanded side view of the double clutch transmission of FIG. 27;

[0064] FIG. 29 illustrates a front view of a further embodiment of a double clutch transmission of the application; and

[0065] FIG. 30 illustrates an expanded side view of the double clutch transmission of FIG. 29.

DETAILED DESCRIPTION

[0066] The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description.

[0067] In the following description, details are provided to describe the embodiments of the application. It shall be apparent to one skilled in the art, however, that the embodiments may be practiced without such details.

[0068] FIGS. 1-14 provide detailed description of an embodiment of a double clutch transmission (DCT) of the application.

[0069] FIG. 1 illustrates a front view of an embodiment of a double clutch transmission 1 of the application. The DCT 1 comprises a relatively large output gearwheel 12, two input shafts 20, 22, two pinions 41, 51 and a reverse gear idler shaft 38. The two input shafts 20, 22 are a solid input shaft 20 (e.g. K1) and a hollow input shaft 22 (e.g. K2). The solid input shaft 20 and the hollow input shaft 22 share the same rotational axis and are non-rotatably connected to two clutch discs 8, 10 of a double clutch 6, separately. The two pinions are the upper pinion 41 and the lower pinion 51. The two pinions are fixed to an upper layshaft 40 and a lower layshaft 50 at their rotational axes respectively. The output gearwheel 12 is fixed to an output shaft 14 at its rotation axis. The two pinions 41, 51 mesh with the output gearwheel 12 separately at different positions of the output gearwheel 12.

[0070] The input shafts 20, 22, the upper layshaft 40, the lower layshaft 50 and the reverse gear idler shaft 38 are parallel to each other at predetermined distances. The distances are provided in radial directions of these shafts, which are better seen in FIG. 2. Other gearwheels are mounted on these shafts respectively meshing with each other according to predetermined manners. The manners of these gearwheels' mounting and meshing are better seen in some of the following figures.

[0071] FIG. 1 further shows a cutting plane A-A for illustrating an expanded cross-section view through the DCT 1, which is shown in FIGS. 2 to 9. The cutting plane A-A passes through the rotational axes of the output gearwheel 12, the lower pinion 51, the input shafts 20, 22, the upper pinion 41 and the reverse gear idler shaft 38. One of the goals of FIGS. 2 to 9 is to further illustrate structure and torque flows of the DCT 1.

[0072] FIG. 2 illustrates the expanded view of the DCT that shows the manners of the gearwheels mounting, which corresponds to FIG. 1.

[0073] According to FIG. 2, the DCT 1 comprises the following shafts, from top to bottom, the reverse gear idler shaft 38, the upper layshaft 40, the hollow input shaft 22, the solid input shaft 20, the lower layshaft 50 and the output shaft 14. The solid input shaft 20 is partially disposed inside the hollow input shaft 22, while the solid input shaft 20 protrudes outside the hollow input shaft 22 at its two ends. The hollow input shaft 22 is mounted onto the solid input shaft 20 by a pair of solid shaft bearings 71 that are disposed between the solid input shaft 20 and the hollow input shaft 22 at two ends of the hollow input shaft 22. As a result, the two input shafts 20, 22 are coupled together such that the solid input shaft 20 is free to rotate inside 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 by a solid shaft bearing 71 at a protruding end of the solid shaft 20 on the left and by a hollow shaft bearing 72 on the right.

[0074] As shown in FIG. 2, a right portion of the solid input shaft 20 is surrounded by the outer input shaft 22 in a radial direction of the input shafts 20, 22. There are three gearwheels mounted on the left exposed portion of the solid input shaft 20. These gearwheels are a fixed wheel fifth gear 26, a fixed wheel seventh gear 27 and a fixed wheel first gear 24. The fixed wheel fifth gear 26, the fixed wheel seventh gear 27 and the fixed wheel first gear 24 are disposed on the exposed portion of the solid shaft 20 from right to left sequentially. The fixed wheel fifth gear 26, the fixed wheel seventh gear 27 and the fixed wheel first gear 24 are fixed to the solid input shaft 20 coaxially. The fixed wheel fifth gear 26 also serves as a fixed wheel third gear 25. On the hollow input shaft 22, there is mounted with a fixed wheel second gear 30 and a fixed wheel fourth gear 32 from the right to the left. The fixed wheel second gear 30 also serves as a fixed wheel reverse gear 34. The fixed wheel sixth gear 32 also serves as a fixed wheel fourth gear 31. Both the fixed wheel second gear 30 and a fixed wheel fourth gear 32 are fixed to the hollow input shaft 22 coaxially.

[0075] The lower layshaft 50 is provided below the solid input shaft 20 and the hollow input shaft 22. There are a number of gearwheels and coupling devices mounted on the lower layshaft 50, which include, from right to the left, the lower pinion 51, an idler second gear 61, a double-sided coupling device 83, an idler fourth gear 63, an idler third gear 62, a double-sided coupling device 82, an idler seventh gear 66, an idler first gear 60 and a single-sided coupling device 84. One layshaft bearing 73 is provided next to both the lower pinion 51 and the idler second gear 61. The other layshaft bearing 73 is provided next to the single-sided coupling device 84 at the left end of the lower layshaft 50. The lower pinion 51 is fixed to the lower layshaft 50 at its rotational axis. The idler second gear 61, the idler fourth gear 63, the idler third gear 62, the idler seventh gear 66 and the idler first gear 60 are mounted on the lower layshaft 50 by bearings separately such that these gearwheels are idlers, being free to rotate around the lower layshaft 50. Both the two double-sided coupling devices 82, 83 are configured to move along the lower layshaft 50 such that they can either engage a gearwheel on their left or right to the lower layshaft 50 respectively. The single-sided coupling device 84 is configured to move along the lower layshaft 50 to engage or disengage the idler first gear 60. The idler second gear 61 meshes with the fixed wheel second gear 30. The idler fourth gear 63 meshes with the fixed wheel fourth gear 31. The idler third gear 62 meshes with the fixed wheel third gear 25. The idler seventh gear 66 meshes with the fixed wheel seventh gear 27.

[0076] The upper layshaft 40 is provided above the input shafts 20, 22. There is provided gearwheels and coupling devices on the upper layshaft 40, which includes, from right to the left, the upper pinion 41, a reverse gear idler wheel 37, a double-sided coupling device 80, an idler sixth gear 65, a idler fifth gear 64, a single-sided coupling device 81 and a park-lock gearwheel 39. One layshaft bearing 73 is positioned between the upper pinion 41 and the reverse gear idler wheel 37. Another layshaft bearing 73 is positioned at the left end of the upper layshaft 40, next to the single-sided coupling device 81. The reverse gear idler wheel 37, the idler sixth gear 65 and the idler fifth gear 64 are mounted on the upper layshaft 40 by bearings respectively such that these gearwheels are free to rotate around the upper layshaft 40. The single-sided coupling device 81 is configured to move along the upper layshaft 40 to engage or disengage the idler fifth gear 64 to the upper layshaft 40. The double-sided coupling device 80 is configured to move along the upper layshaft 40 to engage or disengage any of the reverse gear idler wheel 37 and the idler sixth gear 65 to the upper layshaft 40. The idler sixth gear 65 meshes with the fixed wheel sixth gear 32, while the idler fifth gear 64 meshes with the fixed wheel third gear 25.

[0077] In other words, there are two double-meshing features provided. The first double-meshing feature comprises the idler fifth gear 64 that meshes with the idler third gear 62 via the fixed wheel third gear 25. The second double-meshing feature comprises the idler sixth gear 65 that meshes with the idler fourth gear 63 via the fixed wheel fourth gear 31. A distance 56 between a longitudinal axis of the upper layshaft 40 and a common longitudinal axis of the input shafts 20, 22 is smaller than a distance 58 between the longitudinal axis of the lower layshaft 50 and the common longitudinal axis of the input shafts 20, 22. The upper layshaft 40 carries idler gearwheels 64, 65 of high gear ratios (e.g. 5th & 6th gears). In contrast, the lower layshaft 50 carries idler gearwheels 60, 61, 62, 63 of low gear ratios (e.g. 1st, 2nd, 3rd, & 4th gears). The distances are measured in radial directions of these shafts 20, 22, 40, 50.

[0078] The park-lock gearwheel 39 is a gearwheel fixed onto the upper layshaft 40 for providing a park-lock. The park-lock is a wheel which is provided with a ratchet device, with a click device having a rack element, a claw or similar. The park-lock keeps the upper layshaft 40 and the output shaft 14 from rotating, which stop a vehicle with the DCT 1 from running when the vehicle is parked. When using the park-lock, the park-lock gearwheel 39 on the upper layshaft 40 can be easily engaged to lock the output shaft 14, via the upper pinion 41, via the output gearwheel 12 and stopping the output shaft 14 from rotating.

[0079] The reverse gear idler shaft 38 is provided further above the upper layshaft 40. There is provided gearwheels on the reverse gear idler shaft 38, which includes, from right to the left, the first reverse gearwheel 35 and the second reverse gearwheel 36. Two idler shaft bearings 74 are provided at opposite ends of the reverse gear idler shaft 38. The first reverse gearwheel 35 and the second reverse gearwheel 36 are fixed to the reverse gear idler shaft 38 between the two idler shaft bearings 74. The first reverse gearwheel 35 meshes with the fixed wheel reverse gear 34, while the second reverse gearwheel 36 meshes with the reverse gear idler wheel 37.

[0080] The output shaft 14 is provided below the lower layshaft 50. A pair of output shaft bearings 75 at two opposite ends of the output shaft 14 for supporting. The output gearwheel 12 is mounted on the output shaft 14 coaxially. The output gearwheel 12 is also fixed on the output shaft 14 and meshes with the lower pinion 51 and the upper pinion 41.

[0081] In the present specification, the expressions "mesh" and "comb" with respect to geared wheels or engaged gearwheels are provided as synonyms. The solid input shaft 20 is alternatively termed as an inner input shaft 20, while the hollow input shaft 22 is alternatively termed as an outer input shaft 22. The solid input shaft 20 is alternatively replaced by a hollow shaft and disposed inside the hollow input shaft 22. The term "coupling device" is alternatively termed as "shifting mechanism" for engaging or disengaging gearwheels on a shaft. The double-clutch transmission (DCT) is alternatively termed as double-clutch, double clutch transmission or dual clutch transmission (DCT).

[0082] The fixed wheel first gear 24 is also known as the first fixed gearwheel 24. The fixed wheel third gear 25 is also known as the third fixed gearwheel 25. The fixed wheel fifth gear 26 is also known as the fifth fixed gearwheel 26. The fixed wheel seventh gear 27 is also known as the seventh fixed gearwheel 27. The fixed wheel second gear 30 is also known the second fixed gearwheel 30. The fixed wheel fourth gear 31 is also known as the fourth fixed gearwheel 31. The fixed wheel sixth gear 32 is also known as the sixth fixed gearwheel 32. The fixed wheel reverse gear 34 is also known as the reverse fixed gearwheel 34. The idler first gear 60 is also known as the first gear idler gearwheel 60. The idler second gear 61 is also known as the second gear idler gearwheel 61. The idler third gear 62 is also known as the third gear idler gearwheel 62. The idler fourth gear 63 is also known as the fourth gear idler gearwheel 63. The idler fifth gear 64 is also known as the fifth gear idler gearwheel 64. The idler sixth gear 65 is also known as the sixth gear idler gearwheel 65. The idler seventh gear 66 is also known as the seventh gear idler gearwheel 66. The coupling devices are alternatively known as synchronizers.

[0083] Any one of the input shafts 20, 22 and layshafts 38, 40, 50, can be held by more bearings for better support.

[0084] In figures of the present application, dash lines indicate either alternative positions of the illustrated parts or combing relationship between the gearwheels.

[0085] The application provides the DCT 1 that permits gear ratio shift operations with less loss of driving torque. This is because the gear ratio shift operations can be achieved by selectively connecting one of the two clutch discs 8, 10 of the DCT 1. Therefore, an associated additional main drive clutch can be avoided. The selective connection between the two clutch discs 8, 10 also enables the realization of an automatic transmission that can be operated without interruptions in propulsive power. The propulsive power comprises momentum derived from the rotating gearwheels and shafts inside the DCT 1. Such a transmission is similar in design to a mechanical manual transmission and it has correspondingly very low friction losses. The DCT 1 further provides a parallel manual transmission that can be used for transverse installation in a front-wheel drive vehicle.

[0086] The DCT 1 according to the application can be connected similar to a known manual transmission, such as a parallel manual transmission. In the know manual transmission, a drive shaft for the front axle of a vehicle extends outward from its DCT case, and parallel to the output shaft 14 of the main DCT 1. The arrangement of the known manual transmission provides little space left for actuation of the manual transmission and clutch, and also for an optional electric motor. The optional electric motor can act as a starter device for a combustion engine, as an energy recuperation device for brake operation or as an additional drive means in hybrid vehicles. Having such little space presents a number of difficulties that are solved or at least alleviated by the application. The application provides a DCT 1 that has two clutches or two clutch discs for connecting to an electrical motor and the manual transmission in a compact manner.

[0087] The application provides a compact structure of a parallel transmission. The parallel transmission includes two input shafts, each of which can be non-rotatably coupled via its own clutch to a shaft that is powered by a drive engine of a vehicle. The DCT 1 of the application further provides the output shaft 14 that is parallel to the input shafts 20, 22.

[0088] The DCT 1 according to the application is particularly well suited for transverse installation in front-wheel drive vehicles, in which the front differential, for example, is positioned below the pinions 41, 51. A short overall length of the power train for transmitting torques can be achieved.

[0089] The application provides two or more relatively small pinions 41, 51 on intermediately arranged layshafts 40, 50 that comb with one relatively big output gearwheel 12. The output gearwheel 12 in turn is fixed onto the output shaft 14. This arrangement provides a compact and lightweight DCT 1.

[0090] The application further allows a design in which the output gearwheel 12 is integrated into a transmission differential device without providing an intermediate output shaft of the DCT 1. This allows a very dense packaging situation for the DCT 1.

[0091] It is further advantageous to provide fixed wheels for the even gearwheels on one input shaft and fixed gearwheels for the odd gears on another input shaft. This arrangement provides the above-mentioned power-shift operation in a smooth and efficient manner when gear ratio shift is performed sequentially. This is because the DCT 1 can alternatively engage one of the two clutch discs 8, 10. For example, the power-shift operation from the first gear to the fourth gear causes the solid input shaft 20 and the hollow input shaft 22 being engaged alternatively, which is energy efficient and fast.

[0092] The idler gearwheels 60, 61, 62, 63 of the low gear ratios (e.g. 1st, 2nd, 3rd & 4th) are provided on the same lower layshaft 50, which is advantageous. This is because the lower layshaft 50 has lower rotational speed with larger size for stronger torque, as compared to that of the upper layshaft 40. This arrangement eliminates the need of providing multiple layshafts with larger size for carrying those heavy-load gearwheels 60, 61, 62, 63 of the low gear ratios on different shafts. Therefore, the DCT 1 can be made light with less cost.

[0093] Bearings 73 of the DCT 1 are mounted on the lower layshaft 50 next to the pinion 51 and the gearwheels 61, 60 of lowest gear ratios (e.g. 1st & 2nd gears). This arrangement provides stronger mechanical support to the lower layshaft 50 for less shaft deflection. Similarly, the other bearing 73 is mounted on the upper layshaft 40 next to the upper pinion 41. As a result, the layshafts 40, 50 can be reduced in weight and cost.

[0094] There are only two pinions 41, 51 provided for seven forward gear ratios and one reverse gear ratio. The reduced number of pinions enables reduction in size, cost and weight of the DCT 1.

[0095] A variant of the first embodiment with only four double-shared gearwheels on both of the input shafts 20, 22 has the advantage of providing a better ratio-flexibility and of fewer dependencies. It is beneficial to provide the gearwheels of the first gear, of the second gear and of the pinions 41, 51 close to the bearings for supporting. The gearwheels of these gearwheels of low gears (e.g. 1st gear, 2nd gear, etc) undergo bigger forces than those of the high gears because the drive ratio is higher for the lower gears and reverse gears. Therefore, shafts of low gears must take up stronger driving forces. If those forces are taken up close to the support points of the shafts a reduced shaft bending will occur.

[0096] FIG. 2 illustrates the path of torque flow of a first gear transmission ratio. In FIG. 2, an input torque of the first gear is received from a crankshaft 2 of a combustion engine (not shown). According to FIG. 2, the input torque of the first gear is received by the solid input shaft 20 from the double-clutch 6 of the DCT 1. A torque of the first gear is transmitted from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the single-sided coupling device 84, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14. The single-sided coupling device 84 is engaged to the idler first gear 60 when transmitting the torque of the first gear, which provides the first gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the first gear is two.

[0097] FIG. 3 illustrates the path of torque flow of a second gear transmission ratio. In FIG. 3, an input torque of the second gear is received from the crankshaft 2 of the combustion engine (not shown). According to FIG. 3, the input torque of the second gear is received by the hollow input shaft 22 from the double-clutch 6 of the DCT 1. A torque of the second gear is transmitted from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14. The double-sided coupling device 83 is engaged to the idler second gear 61 when transmitting the torque of the second gear, which provides the second gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the second gear is two.

[0098] FIG. 4 illustrates the path of torque flow of a third gear transmission ratio. In FIG. 4, an input torque of the third gear is received from the crankshaft 2 of the combustion engine (not shown). According to FIG. 4, the input torque of the third gear is received by the solid input shaft 20 from the double-clutch of the DCT 1. A torque of the third gear is transmitted from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14. The double-sided coupling device 82 is engaged to the idler third gear 62 when transmitting the torque of the third gear, which provides the third gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the third gear is two.

[0099] FIG. 5 illustrates the path of torque flow of a fourth gear transmission ratio. In FIG. 5, an input torque of the fourth gear is received from the crankshaft 2 of the combustion engine (not shown). According to FIG. 5, the input torque of the fourth gear is received by the hollow input shaft 22 from the double-clutch 6 of the DCT 1. A torque of the fourth gear is transmitted from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14. The double-sided coupling device 83 is engaged to the idler fourth gear 63 when transmitting the torque of the fourth gear, which provides the fourth gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the fourth gear is two.

[0100] FIG. 6 illustrates the path of torque flow of a fifth gear transmission ratio. In FIG. 6, an input torque of the fifth gear is received from the crankshaft 2 of a combustion engine (not shown). According to FIG. 6, the input torque of the fifth gear is received by the solid input shaft 20 from the double-clutch 6 of the DCT 1. A torque of the fifth gear is transmitted from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the single-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14. The single-sided coupling device 81 is engaged to the idler fifth gear 64 when transmitting the torque of the fifth gear, which provides the fifth gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the fifth gear is two.

[0101] FIG. 7 illustrates the path of torque flow of a sixth gear transmission ratio. In FIG. 7, an input torque of the sixth gear is received from the crankshaft 2 of a combustion engine (not shown). According to FIG. 7, the input torque of the sixth gear is received by the hollow input shaft 22 from the double-clutch 6 of the DCT 1. A torque of the sixth gear is transmitted from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14. The double-sided coupling device 80 is engaged to the idler sixth gear 65 when transmitting the torque of the sixth gear, which provides the sixth gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the sixth gear is two.

[0102] FIG. 8 illustrates the path of torque flow of a seventh gear transmission ratio. In FIG. 8, an input torque of the seventh gear is received from the crankshaft 2 of a combustion engine (not shown). According to FIG. 8, the input torque of the seventh gear is received by the solid input shaft 20 from the double-clutch 6 of the DCT 1. A torque of the seventh gear is transmitted from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14. The double-sided coupling device 82 is engaged to the idler seventh gear 66 when transmitting the torque of the seventh gear, which provides the seventh gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the seventh gear is two.

[0103] FIG. 9 illustrates the path of torque flow of a reverse gear transmission ratio. In FIG. 9, an input torque of the reverse gear is received from the crankshaft 2 of a combustion engine (not shown). According to FIG. 9, the input torque of the reverse gear is received by the hollow input shaft 22 from the double-clutch 6 of the DCT 1. A torque of the reverse gear is transmitted from the hollow input shaft 22, via the fixed wheel reverse gear 34, via the first reverse gearwheel 35 (e.g. R1), via the reverse gear idler shaft 38, via the second reverse gearwheel 36 (e.g. R2), via the reverse gear idler wheel 37, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14. The double-sided coupling device 80 is engaged to the reverse gear idler wheel 37 when transmitting the torque of the reverse gear, which provides the reverse gear ratio of the DCT 1. The number of tooth engagements or engaged gear pairs for the torque transfer of the reverse gear is three.

[0104] Alternative paths for transmitting some of the above-mentioned torque flow paths of the DCT 1 are possible to be provided.

[0105] FIG. 10 illustrates an assembly 100 of a double-sided coupling device 102 with its neighboring gearwheels 101, 103 for engagement. The assembly 100 comprises a shaft 104 with the two coaxially mounted idler gears 101, 103 on two bearings respectively. The coupling device 102 is provided between the idler gear 101 on the left and the idler gear 103 on the right. The coupling device 102 is configured to move along the shaft 104 to selectively engage any of the idler gears 101, 103 at one time. In other words, the idler gears 101, 103 can alternatively be brought into non-rotating engagement with the shaft 104 by the coupling device 102. Symbols for showing the assembly 100 is provided at the right hand side of FIG. 10.

[0106] FIG. 11 illustrates an assembly 110 of a single-sided coupling device 112 with its neighboring gearwheel 113 for engagement. The assembly 110 comprises a shaft 114 with the one coaxially mounted idler gear 113 on a bearing. The coupling device 112 is provided next to the idler gear 113 on the left side. The coupling device 112 is configured to move along the shaft 114 to engage or disengage the idler gears 113. In other words, the idler gear 113 can be brought into non-rotating engagement with the shaft 114 by the single-sided coupling device 112. Symbols for showing the assembly 110 are provided at the right hand side of FIG. 11.

[0107] FIG. 12 illustrates an assembly 120 of an idler gearwheel 121 that is rotatably supported by a shaft 122 on a bearing 123. The idler gearwheel 121 is coaxially mounted onto the shaft 122 via the bearing 123. The bearing 123 enables the idler gearwheel 121 to be freely rotated around the shaft 122. Symbols that represent the assembly 120 are provided at the right hand side of the FIG. 12.

[0108] FIG. 13 illustrates an assembly 130 of a fixed gearwheel 132 that is supported on a shaft 131. The fixed gearwheel 132 is coaxially mounted onto the shaft 131 such that the gearwheel 132 is fixed to the shaft 132. The fixed gearwheel 132 and the shaft 131 are joined as one single body such that torque of the fixed gearwheel 132 is transmitted to the shaft 131 directly, and vice versa.

[0109] A number of fixed gearwheels are rigidly connected to the input shafts 20, 22 and other shafts 14, 38, 40, 50. A symbol as used in the previous figures for such a fixed gearwheel is provided on the left side in FIG. 13. The more commonly used symbol for such a fixed gearwheel is provided on the right side in FIG. 13.

[0110] FIG. 14 illustrates a cross-section through a crankshaft 2 of an internal combustion engine according to the embodiment of the DCT 1. According to FIG. 14, a crankshaft 2 of an internal combustion engine, which is not shown here, is non-rotatably connected to the housing 4 of a double clutch 6. The double clutch 6 includes an inner clutch disc 8 and an outer clutch disc 10, which can be brought into non-rotating engagement with the housing 4 via control elements that are not illustrated here. The solid input shaft 20 is non-rotatably connected to the 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 other clutch disc 10.

[0111] The clutch housing 4 has a larger outer diameter around the inner clutch disc 8 than that around the outer clutch disc 10. Correspondingly, the inner clutch disc 8 has a larger outer diameter than that of the outer clutch disc 10 inside the clutch housing 4. The fact that the larger inner clutch disc 8 on the solid input shaft 20 drives the first gear makes the DCT 1 robust.

[0112] The above-mentioned eight torque flow paths not only provide viable solutions to generate eight gear ratio of the DCT 1, but also offer possibilities of switching from one gear ratio to the other efficiently. For example, gear ratio jumps from the sixth gear to the fourth gear is efficiently provided by the double-meshing of the idler sixth gear 65 and the idler fourth gear 63, via an intermediate gearwheel, namely the fixed wheel fourth gear 31. The gear ratio jump from the sixth gear to the fourth gear does not require stopping the hollow input shaft 22. Furthermore, the double-meshing of the idler sixth gear 65 and the idler fourth gear 63 avoids the need of providing two separate fixed gearwheels on an input shaft. In other words, less space is required on the hollow input shaft 22 because two fixed gearwheels 31, 32 are combined into a single one. The DCT 1 can thus be made lighter and cheaper by the reduction of one gearwheel. The other double-meshing of the idler fifth gear 64 and the idler third gear 62 via the fixed wheel third gear 25 also possesses similar advantages.

[0113] Gearwheels of the two double-meshing are driven by the solid input shaft 20 and the hollow input shaft 22 respectively. This arrangement provides the convenience of gear ratio jumping from third to fourth or sixth efficiently by alternative engagement between the two input shafts 20, 22. Similarly, the gear ratio jumping from fourth to third or fifth is also made efficient. In a like manner, the gear ratio jumping from fifth to fourth or sixth is fast too. Following the same manner, the gear ratio jumping from sixth to third or fifth is very efficient. These gear ratio jumping arrangements provides better control ability to the vehicle with the DCT 1.

[0114] In providing gear meshing or combing for torque transmission, less number of gear tooth engagement (e.g. gear engagement) is preferred. The less number of gear tooth engagement provides lower noise and more efficient torque transmission.

[0115] The DCT 1 drives the gearwheel groups of the first gear and the reverse gear by different input shafts 20, 22. This provides the ability to drive a vehicle change between a slow forward and a slow backward without engaging and disengaging the same group of gearwheels. Just by engaging and disengaging the respective clutches 8, 10 of the two input shafts 20, 22, the DCT 1 enables the vehicle to move back and forth quickly with little loss of the transmission power or gearwheels momentum. This helps in many situations in which a wheel of a vehicle is stuck in a hostile environment such as a snow hole or a mud hole. The vehicle can then be swayed free just by switching between the two clutch discs 8, 10 of the DCT 1.

[0116] FIG. 15-16 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiment.

[0117] FIG. 15 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 is fixed onto an output shaft 14. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. There is also shown a solid input shaft 20, a hollow input shaft 22 and a reverse gear idler shaft 38.

[0118] FIG. 15 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1, which is shown in FIG. 16. One of the goals of FIG. 16 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1. FIG. 16 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 15. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on FIG. 16.

[0119] Referring to FIG. 16, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, a reverse gear idler shaft 38, an upper layshaft 40, a solid input shaft 20, a hollow shaft 22, a lower layshaft 50 and an output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0120] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which serves also as a fixed wheel fifth gear 26, a fixed wheel seventh gear 27, a fixed wheel first gear 24 and a solid shaft bearing 71.

[0121] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30, and a fixed wheel fourth gear 31, which serves also a fixed wheel sixth gear 32.

[0122] The upper layshaft 40 comprises, from the right end to the left end, an upper pinion 41, a layshaft bearing 73, a reverse gear idler wheel 37, a double-sided coupling device 81, an idler sixth gear 65, combing with the fixed wheel fourth gear 31, an idler fifth gear 64, combing with the fixed wheel fifth gear 26, a double-sided coupling device 82, an idler first gear 60, and a layshaft bearing 73.

[0123] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idle shaft bearing 74, a first reverse gear wheel 35, combing with the fixed wheel second gear 30, a second reverse gear wheel 36, combing with the reverse gear idler wheel 37, and an idle shaft bearing 74.

[0124] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, an idler second gear 61, combing with fixed wheel second gear 30, a double-sided coupling device 84, an idler fourth gear 63, combing with fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 83, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, a park-lock gearwheel 39 and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the lower layshaft 40 for providing a park-lock.

[0125] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, an output gearwheel 12 and an output shaft bearing 75.

[0126] Torque flow of the first gear according to FIG. 16 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 82, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0127] Torque flow of the second gear according to FIG. 16 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 84, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0128] Torque flow of the third gear as according to FIG. 16 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0129] Torque flow of the fourth gear according to FIG. 16 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 84, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0130] Torque flow of the fifth gear according to FIG. 16 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0131] Torque flow of the sixth gear according to FIG. 16 starts from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0132] Torque flow of the seventh gear according to FIG. 16 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0133] Torque flow of the reverse gear according to FIG. 16 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the first reverse gear wheel 35, via the reverse gear idler shaft 38, via the second reverse gear wheel 36, via the reverse gear idler wheel 37, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0134] FIG. 17-18 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0135] FIG. 17 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 is fixed onto an output shaft 14. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. There is also shown a solid input shaft 20, a hollow input shaft 22 and a reverse gear idler shaft 38.

[0136] FIG. 17 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1, which is shown in FIG. 18. One of the goals of FIG. 18 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1. FIG. 18 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 17. FIG. 18 illustrates the structure and various torque flows for the several gears of the double clutch transmission gearbox 1.

[0137] Referring to FIG. 18, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the reverse gear idler shaft 38, the upper layshaft 40, the solid input shaft 20, the hollow shaft 22, the lower layshaft 50 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0138] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which also servers as fixed wheel fifth gear 26, a fixed wheel seventh gear 27, a fixed wheel first gear 24 and a solid shaft bearing 71.

[0139] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30, which serves also as a fixed wheel reverse gear 34, and a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32, a hollow shaft bearing 72.

[0140] The upper layshaft 40 comprises, from the right end to the left end, an upper pinion 41, a layshaft bearing 73, a reverse gear idler wheel 37, a double-sided coupling device 80, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with the fixed wheel fifth gear 26, a double-sided coupling device 81, and an idler seventh gear 66, combing with the fixed wheel seventh gear 27, a layshaft bearing 73.

[0141] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idle shaft bearing 74, a first reverse gear wheel 35, combing with the fixed wheel reverse gear 34, a second reverse gear wheel 36, combing with the reverse gear idler wheel 37, and an idle shaft bearing 74.

[0142] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 83, an idler fourth gear 63, combing with the fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 82, an idler first gear 60, combing with the fixed wheel first gear 24, a park-lock gearwheel 39 and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the lower layshaft 50 for providing a park-lock.

[0143] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, an output gearwheel 12 and an output shaft bearing 75.

[0144] Torque flow of the first gear according to FIG. 18 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0145] Torque flow of the second gear as according to FIG. 18 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0146] Torque flow of the third gear according to FIG. 18 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0147] Torque flow of the fourth gear according to FIG. 18 starts from the hollow input shaft 22, via fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0148] Torque flow of the fifth gear according to FIG. 18 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 81, via the upper layshaft 40, to upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0149] Torque flow of the sixth gear according to FIG. 18 starts from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0150] Torque flow of the seventh gear according to FIG. 18 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0151] Torque flow of the reverse gear according to FIG. 18 starts from the hollow input shaft 22, via the fixed wheel reverse gear 34, via the first reverse gear wheel 35, via the reverse gear idler shaft 38, via the second reverse gear wheel 36, via the reverse gear idler wheel 37, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0152] FIG. 19-20 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0153] FIG. 19 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. In some variants of the application, one or more layshafts with further pinions can be provided but this is not shown here. Such a further pinion would then also mesh or comb with the output gearwheel 12. There is also shown a solid input shaft 20, a hollow input shaft 22 and a reverse gear idler shaft 38.

[0154] FIG. 19 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1, which is shown in FIG. 20. For an embodiment, which has more than two layshafts or an additional idler shaft, a cutting plane that leads through all shafts is applied similarly. One of the goals of FIG. 20 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1. FIG. 20 illustrate a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 19. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on FIG. 20.

[0155] Referring to FIG. 20, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, an output shaft 14, an upper layshaft 40, a solid input shaft 20, a hollow shaft 22, a lower layshaft 50 and a reverse gear idler shaft 38. The above-mentioned shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0156] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as solid shaft bearing 71, a fixed wheel third gear 25, which also serves as a fixed wheel fifth gear 26, a fixed wheel first gear 24, a fixed wheel seventh gear 27, and a solid shaft bearing 71.

[0157] The hollow input shaft 22 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, a fixed wheel second gear 30, and a fixed wheel fourth gear 31, which serves also as fixed wheel sixth gear 32.

[0158] The upper layshaft 40 comprises, from the right end to the left end, an upper pinion 41, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 80, an idler fourth gear 63, combing with fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 81, an idler first gear 60, a park-lock gearwheel 39 and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the upper layshaft 40 for providing a park-lock.

[0159] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, a reverse gear idler wheel 37, a double-sided coupling device 83, an idler sixth gear 65, combing with fixed wheel fourth gear 31, an idler fifth gear 64, combing with the fixed wheel fifth gear 26, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, and a layshaft bearing 73.

[0160] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idler shaft bearing 74, a first reverse gear wheel 35, combing with fixed wheel second gear 30, a second reverse gear wheel 36, combing with the reverse gear idler wheel 37, and an idler shaft bearing 74.

[0161] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, an output gearwheel 12 and an output shaft bearing 75.

[0162] Torque flow of the first gear according to FIG. 20 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0163] Torque flow of the second gear according to FIG. 20 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0164] Torque flow of the third gear according to FIG. 20 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0165] Torque flow of the fourth gear according to FIG. 20 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0166] Torque flow of the fifth gear according to FIG. 20 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0167] Torque flow of the sixth gear according to FIG. 20 starts from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0168] Torque flow of the seventh gear according to FIG. 20 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0169] Torque flow of the reverse gear according to FIG. 20 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the first reverse gear wheel 35, via the reverse gear idler shaft 38, via the second reverse gear wheel 36, via the reverse gear idler wheel 37, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0170] FIG. 21-22 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0171] FIG. 21 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. In some variants of the application, one or more layshaft with further pinions can be provided but this is not shown here. Such a further pinion would then also mesh or comb with the output gearwheel 12. FIG. 21 also shows a solid input shaft 20, a hollow input shaft 22 and an output shaft 14 that is mounted with the output gearwheel 12.

[0172] FIG. 21 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1, which is shown in FIG. 22. For an embodiment that has more than two layshafts or an additional idler shaft, a cutting plane that leads through all shafts is applied similarly. One of the goals of FIG. 22 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1. FIG. 22 illustrate a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 21. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained later based on FIG. 22.

[0173] Referring to FIG. 22, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the upper layshaft 40, and the solid input shaft 20, the hollow shaft 22, a lower layshaft 50 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0174] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which serves also as a fixed wheel fifth gear 26, a fixed wheel first gear 24, a fixed wheel seventh gear 27 and a solid shaft bearing 71.

[0175] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30 and a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32.

[0176] The upper layshaft 40 comprises, from the right end to the left end, an upper pinion 41, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 80, an idler fourth gear 63, combing with fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 81, an idler first gear 60, combing with fixed wheel first gear 24 and a layshaft bearing 73.

[0177] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, a park-lock gearwheel 39. a double-sided coupling device 83, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with the fixed wheel fifth gear 26, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27 and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the upper layshaft 40 for providing a park-lock.

[0178] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, the output gearwheel 12 and an output shaft bearing 75.

[0179] Torque flow of the first gear according to FIG. 22 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0180] Torque flow of the second gear according to FIG. 22 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0181] Torque flow of the third gear according to FIG. 22 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0182] Torque flow of the fourth gear according to FIG. 22 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0183] Torque flow of the fifth gear according to FIG. 22 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0184] Torque flow of the sixth gear according to FIG. 22 starts from hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0185] Torque flow of the seventh gear according to FIG. 22 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0186] FIG. 23-24 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0187] FIG. 23 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51, which is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41, which is provided on an upper layshaft 40. There are further provided a solid input shaft 20, a hollow input shaft 22 and a reverse gear idler shaft 38.

[0188] FIG. 23 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1, which is shown in FIG. 24. For the embodiment, which has more than two layshafts or an additional idler shaft, a cutting plane that leads through all shafts is applied similarly. One of the goals of FIG. 24 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1. FIG. 24 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 23. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on FIG. 24.

[0189] Referring to FIG. 24, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the upper layshaft 40, the solid input shaft 20, the hollow shaft 22, the lower layshaft 50, the reverse gear idler shaft 38 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0190] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which serves also as a fixed wheel fifth gear 26, a fixed wheel solid shaft 23, a fixed wheel first gear 24, and a solid shaft bearing 71.

[0191] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30, a hollow shaft bearing 72 and a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32.

[0192] The upper layshaft 40 comprises, from the right end to the left end, the upper pinion 41, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 80, an idler fourth gear 63, combing with the fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 81, an idler first gear 60, combing with the fixed wheel first gear 24, a park-lock gearwheel 39 and a layshaft bearing 73.

[0193] The lower layshaft 50 comprises, from the right end to the left end, the lower pinion 51, a layshaft bearing 73, a reverse gear idler wheel 37, a double-sided coupling device 83, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with the fixed wheel fifth gear 26, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, and the layshaft bearing 73.

[0194] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idler shaft bearing 74, a second reverse gear wheel 36, combing with the reverse gear idler wheel 37 and a first reverse gear wheel 35, combing with the fixed wheel solid shaft 23, and an idler shaft bearing 74.

[0195] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, the output gearwheel 12 and an output shaft bearing 75.

[0196] Torque flow of the first gear according to FIG. 24 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0197] Torque flow of the second gear according to FIG. 24 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0198] Torque flow of the third gear according to FIG. 24 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0199] Torque flow of the fourth gear according to FIG. 24 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0200] Torque flow of the fifth gear according to FIG. 24 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0201] Torque flow of the sixth gear according to FIG. 7 starts from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0202] Torque flow of the seventh gear according to FIG. 24 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0203] Torque flow of the reverse gear according to FIG. 24 starts from the solid input shaft 20, via the fixed wheel solid shaft 23, via the first reverse gear wheel 35, via the reverse gear idler shaft 38, via the second reverse gear wheel 36, via the reverse gear idler wheel 37, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0204] FIG. 25-26 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0205] FIG. 25 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. In some variants of the application, one or more layshaft with further pinions can be provided but this is not shown here. Such a further pinion would then also mesh or comb with the output gearwheel 12. There is also shown a solid input shaft 20, a hollow input shaft 21 and a reverse gear idler shaft 38.

[0206] FIG. 25 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1, which is shown in FIG. 26. For an embodiment that has omre than two layshafts or an additional idler shaft, a cutting plane, which leads through all shafts, is applied similarly. One of the goals of FIG. 26 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1.

[0207] FIG. 26 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 25. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on FIG. 26.

[0208] Referring to FIG. 26, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the reverse gear idler shaft 38, the upper layshaft 40, the solid input shaft 20, the hollow shaft 21, the lower layshaft 50 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 21 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 21 at a right end.

[0209] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as solid shaft bearing 71, a fixed wheel third gear 25, which serves also as a fixed wheel fifth gear 26, a fixed wheel first gear 24, a fixed wheel seventh gear 27 and a solid shaft bearing 71.

[0210] The hollow input shaft 21 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30, a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32, a fixed wheel solid shaft 23 and a hollow shaft bearing 72.

[0211] The upper layshaft 40 comprises, from the right end to the left end, an upper pinion 41, a layshaft bearing 73, a reverse gear idler wheel 37, a double-sided coupling device 80, an idler fourth gear 63, combing with the fixed wheel fourth gear 31, a park-lock gearwheel 39, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 81, an idler first gear 60, combing with the fixed wheel first gear 24, and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the upper layshaft 40 for providing a park-lock.

[0212] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idler shaft bearing 74, a second reverse gear wheel 36, combing with the reverse gear idler wheel 37, a first reverse gear wheel 35, combing with the fixed wheel solid shaft 23, and an idler shaft bearing 74.

[0213] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 83, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with fixed wheel fifth gear 26, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, and a layshaft bearing 73.

[0214] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, the output gearwheel 12 and an output shaft bearing 75.

[0215] Torque flow of the first gear according to FIG. 26 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0216] Torque flow of the second gear according to FIG. 26 starts from the hollow input shaft 21, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0217] Torque flow of the third gear according to FIG. 26 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0218] Torque flow of the fourth gear according to FIG. 26 starts from the hollow input shaft 21, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0219] Torque flow of the fifth gear according to FIG. 26 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the lower layshaft 50, to the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0220] Torque flow of the sixth gear according to FIG. 26 starts from the hollow input shaft 21, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0221] Torque flow of the seventh gear according to FIG. 26 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0222] Torque flow of the reverse gear according to FIG. 26 starts from the hollow input shaft 21, via the fixed wheel solid shaft 23, via the first reverse gear wheel 35, via the reverse gear idler shaft 38, via the second reverse gear wheel 36, via the reverse gear idler wheel 37, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0223] FIG. 27-28 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0224] FIG. 27 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. The output gearwheel 12 also meshes with a reverse pinion 55 that is provided on a reverse gear shaft 38. There is further shown a solid input shaft 20, a hollow input shaft 22 and an output gearwheel 12 that carries the output gearwheel 12. In some variants of the application, at least one further layshaft with a further pinion can be provided but this is not shown here. Such a further pinion would then also mesh or comb with the output gearwheel 12.

[0225] FIG. 27 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1 that is shown in FIG. 28. For an embodiment, which has more than two layshafts or an additional idler shaft, a cutting plane that leads through all shafts is applied similarly. One of the goals of FIG. 28 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1. FIG. 28 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 27. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on the FIG. 28.

[0226] The double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the reverse gear shaft 38, the upper layshaft 40, the solid input shaft 20, the hollow shaft 22, the lower layshaft 50 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0227] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which servers also as a fixed wheel fifth gear 26, a fixed wheel first gear 24, a fixed wheel seventh gear 27 and a solid shaft bearing 71.

[0228] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30 and a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32.

[0229] The reverse gear shaft 38 comprises, from the right end to the left end, a reverse pinion 55, an idler shaft bearing 74, a park-lock gearwheel 39, a single-sided coupling device 84 and a first reverse gear wheel 35. The reverse pinion 55 is the final drive 55, in addition to the final drive 41 on the upper layshaft 40 and the final drive 51 on the lower layshaft 50.

[0230] The upper layshaft 40 comprises, from the right end to the left end, the upper pinion 41, a layshaft bearing 73, a single-sided coupling device 80, an idler fourth gear 63, combing with the fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 81, an idler first gear 60, combing with the fixed wheel first gear 24, and a layshaft bearing 73.

[0231] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 83, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with the fixed wheel fifth gear 26, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, and a layshaft bearing 73.

[0232] The output shaft 14 comprises, from the right end to the left end, an output shaft bearing 75, the output gearwheel 12 and an output shaft bearing 75.

[0233] Torque flow of the first gear according to FIG. 28 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 81, via the upper layshaft 40, the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0234] Torque flow of the second gear according to FIG. 28 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0235] Torque flow of the third gear according to FIG. 28 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0236] Torque flow of the fourth gear according to FIG. 28 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the single-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0237] Torque flow of the fifth gear according to FIG. 28 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0238] Torque flow of the sixth gear according to FIG. 28 from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0239] Torque flow of the seventh gear according to FIG. 28 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0240] Torque flow of the reverse gear according to FIG. 28 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the first reverse gear wheel 35 (e.g. R), via the single-sided coupling device 84, via the reverse gear shaft 38, via the reverse pinion 55, via the output gearwheel 12, to the output shaft 14.

[0241] FIG. 29-30 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0242] FIG. 29 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. There is also shown a solid input shaft 20, a hollow input shaft 22, a reverse gear shaft 38 and an output shaft 14. In some variants of the application, at least one further layshaft with a further pinion can be provided but this is not shown here. Such a further pinion would then also mesh or comb with the output gearwheel 12.

[0243] FIG. 29 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1 that is shown in FIG. 30. For an embodiment, which has more than two layshafts or an additional idler shaft, a cutting plane that leads through all shafts is applied similarly. One of the goals of FIG. 30 is to further illustrate the structure and the torque flows through the embodiment of the gearbox 1.

[0244] FIG. 30 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 29. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on FIG. 30.

[0245] Referring to FIG. 30, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the reverse gear idler shaft 38, the upper layshaft 40, the solid input shaft 20, the hollow shaft 22, the lower layshaft 50 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0246] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which servers also as a fixed wheel fifth gear 26, a fixed wheel solid shaft 23, a fixed wheel first gear 24, a fixed wheel seventh gear 27 and a solid shaft bearing 71.

[0247] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30, a solid shaft bearing 71, and a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32.

[0248] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idler shaft bearing 74, a fixed wheel reverse gear 34, a single-sided coupling device 84, a first reverse gear wheel 35, combing with the fixed wheel solid shaft 23, and an idler shaft bearing 74.

[0249] The upper layshaft 40 comprises, from the right end to the left end, an upper pinion 41, a layshaft bearing 73, an idler second gear 61, combing with both the fixed wheel second gear 30 and the fixed wheel reverse gear 34, a double-sided coupling device 80, an idler fourth gear 63, combing with the fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 81, an idler first gear 60, combing with the fixed wheel first gear 24, a park-lock gearwheel 39, and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the upper layshaft 40 for providing a park-lock.

[0250] The lower layshaft 50 comprises, from the right end to the left end, a lower pinion 51, a layshaft bearing 73, a single-sided coupling device 83, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with fixed wheel fifth gear 26, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, and a layshaft bearing 73.

[0251] Torque flow of the first gear according to FIG. 30 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0252] Torque flow of the second gear according to FIG. 30 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0253] Torque flow of the third gear according to FIG. 30 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 81, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0254] Torque flow of the fourth gear according to FIG. 30 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the single-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0255] Torque flow of the fifth gear according to FIG. 30 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0256] Torque flow of the sixth gear according to FIG. 30 starts from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the single-sided coupling device 83, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0257] Torque flow of the seventh gear according to FIG. 30 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0258] Torque flow of the reverse gear according to FIG. 30 starts from the solid input shaft 20, via the fixed wheel solid shaft 23, via the first reverse gear wheel 35, via the single-sided coupling device 84, via the reverse gear idler shaft 38, via the fixed wheel reverse gear 34, via the idler second gear 61, via the double-sided coupling device 80, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0259] FIG. 31-32 illustrates a further embodiment of the application. The embodiment includes parts that are similar to the parts of previously described embodiments.

[0260] FIG. 31 shows a front view of the gearbox 1 of the application. A relatively big output gearwheel 12 meshes with a lower pinion 51 that is provided on a lower layshaft 50. The output gearwheel 12 further meshes with an upper pinion 41 that is provided on an upper layshaft 40. There is also shown a solid input shaft 20, a hollow input shaft 22, a reverse gear shaft 38 and an output shaft 14. In some variants of the application, at least one further layshaft with a further pinion can be provided but this is not shown here. Such a further pinion would then also mesh or comb with the output gearwheel 12.

[0261] FIG. 31 further comprises a cutting plane A-A for illustrating the cross-section through the gearbox 1. For an embodiment, which has more than two layshafts or an additional idler shaft, a cutting plane that leads through all shafts is applied similarly. FIG. 32 further illustrates the structure and the torque flows through the embodiment of the gearbox 1.

[0262] FIG. 32 illustrates a simplified cross-section through the double clutch transmission gearbox 1 of FIG. 31. Structure and various torque flows for the several gears of the double clutch transmission gearbox 1 are explained based on FIG. 32.

[0263] Referring to FIG. 32, the double clutch transmission gearbox 1 comprises the following shafts, from top to bottom, the reverse gear idler shaft 38, the upper layshaft 40, the solid input shaft 20, the hollow shaft 22, the lower layshaft 50 and the output shaft 14. These shafts are provided parallel to each other at predetermined mutual distances inside the gearbox 1. The hollow shaft 22 is arranged concentrically around the solid shaft 20. The solid input shaft 20 protrudes outside the hollow input shaft 22 at a right end.

[0264] The solid input shaft 20 comprises, from the right end to the left end, a solid shaft bearing 71, a hollow shaft bearing 72, which serves also as a solid shaft bearing 71, a fixed wheel third gear 25, which servers also as a fixed wheel fifth gear 26, a fixed wheel seventh gear 27, a fixed wheel first gear 24, and a solid shaft bearing 71.

[0265] The hollow input shaft 22 comprises, from the right end to the left end, a hollow shaft bearing 72, a fixed wheel second gear 30, a solid shaft bearing 71, which also serve as a hollow shaft bearing 72, and a fixed wheel fourth gear 31, which serves also as a fixed wheel sixth gear 32.

[0266] The upper layshaft 40 comprises, from the right end to the left end, the upper pinion 41, a layshaft bearing 73, an idler reverse gear 36, a double-sided coupling device 83, an idler fourth gear 63, combing with the fixed wheel fourth gear 31, an idler third gear 62, combing with the fixed wheel third gear 25, a double-sided coupling device 82, an idler seventh gear 66, combing with the fixed wheel seventh gear 27, a park-lock gearwheel 39, and a layshaft bearing 73. The park-lock gearwheel 39 is a gearwheel fixed onto the upper layshaft 40 for providing a park-lock.

[0267] The reverse gear idler shaft 38 comprises, from the right end to the left end, an idler shaft bearing 74, a first reverse gear wheel 35 fixed onto the reverse gear idler shaft 38, a second reverse gear wheel 34 fixed onto the second reverse gear wheel 38, and an idler shaft bearing 74.

[0268] The lower layshaft 50 comprises, from the right end to the left end, the lower pinion 51, a layshaft bearing 73, an idler second gear 61, combing with the fixed wheel second gear 30, a double-sided coupling device 81, an idler sixth gear 65, combing with the fixed wheel sixth gear 32, an idler fifth gear 64, combing with fixed wheel fifth gear 26, a double-sided coupling device 80, an idler first gear 60, combing with the fixed wheel first gear 24, and a layshaft bearing 73.

[0269] Torque flow of the first gear according to FIG. 32 starts from the solid input shaft 20, via the fixed wheel first gear 24, via the idler first gear 60, via the double-sided coupling device 80, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0270] Torque flow of the second gear according to FIG. 32 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the idler second gear 61, via the double-sided coupling device 81, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0271] Torque flow of the third gear according to FIG. 32 starts from the solid input shaft 20, via the fixed wheel third gear 25, via the idler third gear 62, via the double-sided coupling device 82, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0272] Torque flow of the fourth gear according to FIG. 32 starts from the hollow input shaft 22, via the fixed wheel fourth gear 31, via the idler fourth gear 63, via the double-sided coupling device 83, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0273] Torque flow of the fifth gear according to FIG. 32 starts from the solid input shaft 20, via the fixed wheel fifth gear 26, via the idler fifth gear 64, via the double-sided coupling device 80, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0274] Torque flow of the sixth gear according to FIG. 32 starts from the hollow input shaft 22, via the fixed wheel sixth gear 32, via the idler sixth gear 65, via the double-sided coupling device 81, via the lower layshaft 50, via the lower pinion 51, via the output gearwheel 12, to the output shaft 14.

[0275] Torque flow of the seventh gear according to FIG. 32 starts from the solid input shaft 20, via the fixed wheel seventh gear 27, via the idler seventh gear 66, via the double-sided coupling device 82, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0276] Torque flow of the reverse gear according to FIG. 32 starts from the hollow input shaft 22, via the fixed wheel second gear 30, via the first reverse gear wheel 35, via the reverse gear idler shaft 38, via the second reverse gear wheel 34, via the idler reverse gear wheel 36, via the double-sided coupling device 83, via the upper layshaft 40, via the upper pinion 41, via the output gearwheel 12, to the output shaft 14.

[0277] Although the above description contains much specificity, these should not be construed as limiting the scope of the embodiments but merely providing illustration of the foreseeable embodiments. Especially the above stated advantages of the embodiments should not be construed as limiting the scope of the embodiments but merely to explain possible achievements if the described embodiments are put into practice. Thus, the scope of the embodiments should be determined by the claims, rather than by the examples given.

[0278] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

Claims

1. A double-clutch transmission, comprising: an inner input shaft and an outer input shaft, at least a portion of the inner input shaft surrounded by the outer input shaft; a first clutch connected to the inner input shaft and a second clutch connected to the outer input shaft; a first layshaft and a second layshaft spaced apart from the inner input shaft and outer input shaft and arranged in parallel to the inner input shaft and outer input shaft; gearwheels arranged on the first layshaft, on the second layshaft, on the inner input shaft and on the outer input shaft, the gearwheels comprising a first gearwheel group, a second gearwheel group, a third gearwheel group, a fourth gearwheel group, a fifth gearwheel group, a sixth gearwheel group and a seventh gearwheel group for providing seven sequentially increasing forward gear output speeds, the first gearwheel group comprising a first fixed gearwheel on the inner input shaft, meshing with a first gear idler gearwheel on one of the first layshaft or the second layshaft, the third gearwheel group comprising a third fixed gearwheel on the inner input shaft, meshing with a third gear idler gearwheel on one of the first layshaft or the second layshaft, the fifth gearwheel group comprising a fifth fixed gearwheel on the inner input shaft, meshing with a fifth gear idler gearwheel on one of the first layshaft or the second layshaft, the seventh gearwheel group comprising a seventh fixed gearwheel on the inner input shaft, meshing with a seventh gear idler gearwheel on one of the first layshaft or the second layshaft, the second gearwheel group comprising a second fixed gearwheel on the outer input shafts, meshing with a second gear idler gearwheel on one of the first layshaft or the second layshaft, the fourth gearwheel group comprising a fourth fixed gearwheel on the outer input shafts, meshing with a fourth gear idler gearwheel on one of the first layshaft or the second layshaft, the sixth gearwheel group comprising a sixth fixed gearwheel on the outer input shafts, meshing with a sixth gear idler gearwheel on one of the first layshaft or the second layshaft, and each one of the gearwheel groups comprising a coupling device arranged on one of the first layshaft or the second layshaft to selectively engage one of the idler gearwheels for selecting one of the seven gears, and the fourth fixed gearwheel further meshing with the sixth gear idler gearwheel, wherein the third fixed gearwheel further meshes with the fifth gear idler gearwheel.

2. The double clutch transmission according to claim 1, further comprising a reverse gear idler shaft and a reverse gearwheel mounted on the reverse gear idler shaft, the reverse gearwheel meshing with one of the gearwheels on one of the layshafts for providing a reverse gear.

3. The double-clutch transmission according to claim 2, wherein the first gear and the reverse gear are driven by different input shafts.

4. The double-clutch transmission according to claim 1, further comprising a second reverse gearwheel on the reverse gear idler shaft, the two reverse gearwheels meshing with two of the gearwheels on the layshafts.

5. The double-clutch transmission according to claim 1, wherein a distance between one of the layshafts with idler gearwheels of low gear ratios and the inner input shaft is greater than a distance between another one of the layshafts with the idler gearwheels of high gear ratios and the inner input shaft.

6. The double-clutch transmission according to claim 1 further comprising a park-lock gearwheel fixed onto one of the layshafts that has a pinion for providing a park-lock.

7. The double-clutch transmission according to claim 1, wherein at least two of the first gear idler gearwheel, the second gear idler gearwheel, the third gear idler gearwheel and the fourth gear idler gearwheel are mounted on the same layshaft.

8. The double-clutch transmission according to claim 7, wherein the first gear idler gearwheel, the second gear idler gearwheel, the third gear idler gearwheel and the fourth gear idler gearwheel are mounted on the same layshaft.

9. The double-clutch transmission according to claim 1, wherein at least two of the fifth gear idler gearwheel, the sixth gear idler gearwheel and the seventh gear idler gearwheel are mounted on the same layshaft.

10. The double-clutch transmission according to claim 9, wherein the fifth gear idler gearwheel, the sixth gear idler gearwheel and the seventh gear idler gearwheel are mounted on the same layshaft.

11. The double-clutch transmission according to claim 8, wherein the first gear idler gearwheel, the second gear idler gearwheel, the third gear idler gearwheel and the fourth gear idler gearwheel are mounted on one of the layshafts, and wherein the fifth gear idler gearwheel, the sixth gear idler gearwheel and the seventh gear idler gearwheel are mounted on the other layshaft.

12. The double-clutch transmission according to claim 1, further comprising bearings for supporting the layshafts, at least two of the bearings being provided next to the first gear idler gearwheel and the second gear idler gearwheel.

13. The double-clutch transmission according to claim 1, wherein the third gearwheel group and the fifth gearwheel group are driven by the inner input shaft, and the fourth gearwheel group and the sixth gearwheel groups are driven by the outer input shaft.

14. The double-clutch transmission according to claim 8, wherein the third gear idler gearwheel and the fourth gear idler gearwheel are provided between the first gear idler gearwheel and the second gear idler gearwheel.

15. The double-clutch transmission according to claim 1, further comprising at least two pinions that are provided on the two layshafts respectively, each of the two pinions being next to a bearing for support.

16. A gearbox, comprising: an inner input shaft and an outer input shaft, at least a portion of the inner input shaft surrounded by the outer input shaft; a first clutch connected to the inner input shaft and a second clutch connected to the outer input shaft; a first layshaft and a second layshaft spaced apart from the inner input shaft and outer input shaft and arranged in parallel to the inner input shaft and outer input shaft; gearwheels arranged on the first layshaft, on the second layshaft, on the inner input shaft and on the outer input shaft, the gearwheels comprising a first gearwheel group, a second gearwheel group, a third gearwheel group, a fourth gearwheel group, a fifth gearwheel group, a sixth gearwheel group and a seventh gearwheel group for providing seven sequentially increasing forward gear output speeds, the first gearwheel group comprising a first fixed gearwheel on the inner input shaft, meshing with a first gear idler gearwheel on one of the first layshaft or the second layshaft, the third gearwheel group comprising a third fixed gearwheel on the inner input shaft, meshing with a third gear idler gearwheel on one of the first layshaft or the second layshaft, the fifth gearwheel group comprising a fifth fixed gearwheel on the inner input shaft, meshing with a fifth gear idler gearwheel on one of the first layshaft or the second layshaft, the seventh gearwheel group comprising a seventh fixed gearwheel on the inner input shaft, meshing with a seventh gear idler gearwheel on one of the first layshaft or the second layshaft, the second gearwheel group comprising a second fixed gearwheel on the outer input shafts, meshing with a second gear idler gearwheel on one of the first layshaft or the second layshaft, the fourth gearwheel group comprising a fourth fixed gearwheel on the outer input shafts, meshing with a fourth gear idler gearwheel on one of the first layshaft or the second layshaft, the sixth gearwheel group comprising a sixth fixed gearwheel on the outer input shafts, meshing with a sixth gear idler gearwheel on one of the first layshaft or the second layshaft, and each one of the gearwheel groups comprising a coupling device arranged on one of the first layshaft or the second layshaft to selectively engage one of the idler gearwheels for selecting one of the seven gears, and the fourth fixed gearwheel further meshing with the sixth gear idler gearwheel, wherein the third fixed gearwheel further meshes with the fifth gear idler gearwheel; and an output gearwheel that is adapted to separately mesh with the two pinions for providing an output torque.

17. The power train device according to claim 16, the power train device comprising at least one power source for generating a driving torque.

18. The power train device of claim 17, wherein the power source comprises a combustion engine.

19. The power train device of claim 17, wherein the power source comprises an electric motor.

20. (canceled)