GB2525077A

GB2525077A - A double clutch transmission

Info

Publication number: GB2525077A
Application number: GB1502958.0A
Authority: GB
Inventors: Christian Kunze; Mathias Remmler; Christoph Hau; Christian Rubsam; Olaf Heldmann
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2014-03-10
Filing date: 2015-02-23
Publication date: 2015-10-14
Also published as: GB201502958D0; DE102014003277A1; CN104913012A; CN104913012B

Abstract

A double clutch manual transmission comprises a drive shaft 1, a first main shaft 2, a first friction clutch 8, a second main shaft 3, a second friction clutch 9 and a plurality of gear sets comprising gears 4, 5, 22, 6, 7, 23 on one of the main shafts 2, 3 which mesh with gears 33, 29, 27, 34, 30, 28 on at least one first auxiliary shaft 25. At least two of the gear sets 4, 33; 6, 34 comprise idler gears 33, 34, meshing with fixed gears 4, 6, are coupled by a double-acting first selector sleeve 31 to the auxiliary shaft 25. At least one gear set 22, 27 comprises an idler gear 22 which is coupled by a second selector sleeve 10 to the main shaft 2, and meshes with a fixed gear 27 on one of the auxiliary shafts 25. The selector sleeves are operated by a sequencing mechanism comprising first and second rotation-translation mechanisms 71, 72 having a pin and cam devices 46 or coulisses which are driven by electric motors.

Description

A double clutch transmission

Description

The present invention relates to a double clutch transmission, as known from US2008/O1 3481 91 for example. This conventional double clutch trans-mission comprises two main shafts, which can respectively be coupled to a common drive shaft via a separate friction clutch. Each main shaft carries two fixed gears which mesh with idler gears on two auxiliary shafts. The distance between the fixed gears of the same main shaft must be large enough so that a selector sleeve has sufficient space between the fixed gears of the same main shaft, by means of which one of the idler gears can be coupled to its auxiliary shaft. Since the diameter of the selector sleeve is generally smaller than that of the idler gears, such a transmission contains a large amount of unused space between the fixed gears, or it requires a large amount of space.

It is an object of the invention to provide a double clutch transmission with improved space utilization.

This object is achieved by means of an embodiment of the invention in which in a double clutch transmission with a drive shaft, a main shaft which can be coupled via a first friction clutch to the drive shaft, a second main shaft which can be coupled via a second friction clutch to the drive shaft, and a plurality of gear sets which respectively comprise a gear on the drive side on one of the main shafts and a gear on the output side on at least one first auxiliary shaft which meshes with the gear on the drive side, wherein at least two of the gear sets comprise idler gears which can be coupled from a similar, double-acting first selector sleeve to the first auxiliary shaft, of which one of the idler gears meshes with a fixed gear of the first main shaft and the other one meshes with a fixed gear of the second main shaft, and at least one gear set designated here as the gear set which is switched to the main shaft side comprises an idler gear on one of the main shafts, which can be coupled by a second selector sleeve to the main shaft, and a fixed gear on one of the auxiliary shafts. By distributing the selector sleeves among the main and auxilia-ry shafts, a balanced number of components can be reached on each shaft, as a result of which the shafts can be kept short and unused space on the shafts is pre-vented.

In particular, the second selector sleeve can be arranged in a space-saving manner between the idler gear that can be coupled by said sleeve to the main shaft and the friction clutch which is associated with said main shaft.

A second auxiliary shaft can be provided to provide a large number of gears in the case of short lengths of the shafts, and at least one gear set can corn-prise an idler gear which can be coupled by a third selector sleeve to the second auxiliary shaft and which meshes with a fixed gear of the first main shaft.

The third selector sleeve can be double-acting like the first one, and a gear set can comprise an idler gear which can be coupled by the third selector sleeve to the second auxiliary shaft, and comprise a fixed gear on the second main shaft.

Furthermore, a gear set can be provided which is switched on the side of the main shaft and which comprises an idler gear on a main shaft that differs from the one of the first gear sets switched on the side of the main shaft, which idler gear can be coupled by a fourth selector sleeve to said other main shaft, and which comprises a fixed gear on one of the auxiliary shafts. Said auxiliary shaft can be the same one which also carries the fixed gear of the first gear set switched on the side of the main shaft, but the two fixed gears can also be distributed among different auxiliary shafts.

As a result, three gear sets can be driven by each main shaft, two each whose gear on the drive side is a fixed gear, and one each in which the gear on the drive side is an idler gear, so that a transmission with a total of six gears can be realized.

Gear sets whose gears on the drive side are situated on the first main shaft can represent odd-numbered gears of the transmission, whereas gear sets whose gears on the drive side are situated on the second main shaft can rep-resent even-numbered gears. Interruption-free shifting between even-numbered s and odd-numbered gears is thus possible by opening one of the friction clutches and simultaneously closing the other one.

Interruption-free shifting is not possible between two gears which are shifted by the same double-acting selector sleeve (i.e. the first or the third selector sleeve) because it is unable to couple two idler gears to the same auxiliary shaft simultaneously. In order to enable interruption-free shifting between directly succes-sive gears, the gears provided by means of these idler gears should not be directly successive gears, i.e. at least one further gear with an intermediary gear ratio should lie between the gears which are presented by gear sets by the same double- acting selector sleeve. If -as mentioned above -the odd-numbered gears are pro-vided via the first main shaft and the even-numbered gears via the second main shaft of the transmission, it is necessary that at least two gears with an intermediary gear ratio are situated between the gear sets shifted by the same double-acting selector sleeve. The number of the gears in between is preferably precisely two because an excessive number of gears with intermediary gear ratio would lead to strongly differing diameters of the gears that can be coupled by the double-acting selector sleeve to the auxiliary shaft, thereby leading to an adverse utilization of space.

In order to minimize the number of components and to optimize the compactness of the transmission, at least one of the main shafts can carry a fixed gear which belongs the two gear sets, i.e. which meshes with idler gears on the first and on the second auxiliary shaft.

A first sequencing mechanism can be provided in order to convert a continuous drive motion such as the rotation of a servomotor into a movement of one of the selector sleeves from a neutral position to a shifting position which cou- ples the idler gear of one of the gear sets to its shafts, and after reaching the shift-ing position into a closing motion of the first friction clutch driving said gear set. As a result of the same continuous driving motion, a gear can successively be preselect-ed and subsequently the gear can be engaged by closing the associated friction coupling.

Such a sequencing mechanism can comprise a first and second rota- tion-translation converter module, wherein the converter modules respectively com- prise a drive part which is pivotable about an axis and a drive pad driven in transla-tory motion by a pivoting movement of the drive part, the drive parts are rotationally coupled, and the output part of the first converter module cooperates with the first friction coupling and the output part of the second converter module cooperates with the one selector sleeve.

Such a converter module can especially comprise a coulisse and a cam cooperating with the coulisse in an interlocking fashion, wherein the cam and the coulisse are pivotable relative to each other about the said axis, and the cou-lisse comprises at least one section extending helically about the axis and at least one section extending in the circumferential direction. When the cam cooperates with the helical section of the coulisse, any rotation of cam and coulisse with respect to each other also produces a translatory movement. When the cam cooperates with the section extending in the circumferential direction, the cam on the coulisse can rotate against each other without producing a translatory motion. As a result of a suitable arrangement of the sections on the coulisses of the converter module, the aforementioned movement sequence can be realized in which the selector sleeve is displaced to the shifting position first and the friction coupling is closed thereafter.

The sequencing mechanism can comprise a third rotation-translation converter module, wherein the selector sleeve actuated by the second converter module is one of the double-acting selector sleeves and the third converter module actuates the second selector sleeve.

A second sequencing mechanism should be provided in order to convert a continuous drive motion into a movement of one of the selector sleeves from a neutral position to a shifting position in which it couples the idler gear of a gear set driveable via second friction clutch to iS shaft and -after reaching the shifting position -to a closing position of the second friction clutch.

Since the double-acting selector sleeves respectively connect their auxiliary shaft in one of its shifting positions to the first main shaft and in the second shifting position to the second main shaft so as to enable transfer of torque, a selec-tion mechanism should appropriately be provided which in a first state connects the first selector sleeve to the first sequencing mechanism and the third selector sleeve to the second sequencing mechanism, and which connects the first selector sleeve to the second sequencing mechanism and the third selector sleeve to the first se-quencing mechanism in a second state. As a result, each sequencing mechanism can access the first or third selector sleeve as required. The second and fourth Se-lector sleeve on the other hand can respectively be fixedly assigned to one of the sequencing mechanisms.

Further features and advantages of the invention are provided in the following description of embodiments by reference to the enclosed drawings, where-in: Fig. 1 shows a schematic view of a manual transmission ac-cording to a first embodiment of the invention in the neutral position; Fig. 2 shows a perspective view of a ring used in the trans-mission of Fig. 1; Fig. 3 shows a top view of a gear wheel used in the trans-mission of Fig. 1; Fig. 4 shows a top view of a pressure ring used in the trans-mission of Fig. 1; Fig. 5 shows a perspective view of parts of a sequencing mechanism and a selection mechanism of the manual transmission of Fig. 1; Fig. 6 shows the parts shown in Fig. 5 in an axial sectional view; Fig. 7 shows the parts of Figs. 5 and 6 in the neutral position of the manual transmission with preselected first gear; Fig. 8 shows the parts with engaged first gear; Fig. 9 shows the parts with engaged first and preselected second gear; Fig. 10 shows the parts after the engagement of the second gear with still preselected first gear; Fig. 11 shows the parts with engaged second gear after can-celling the preselection of the first gear; Fig. 12 shows a preparatory step for the engagement of the third gear; Fig. 13 shows the parts with preselected third gear; Fig. 14 shows the parts when disengaging the second gear; Fig. 15 shows the parts with engaged third gear; Fig. 16 shows the parts with engaged third and preselected fourth gear; Fig. 17 shows the change of load from the third to the fourth gear; Fig. 18 shows the parts with engaged fourth gear; Fig. 19 shows the parts with engaged fifth and still preselected fourth gear; Fig. 20 shows the parts after cancelling the preselection al the fourth gear; Fig. 21 shows the parts with engaged sixth g!ar; Fig. 22 shows a schematic representation of a manual trans- mission according to a second embodiment of the in-vention; Fig. 23 shows a third embodiment of the manual transmission, and Fig. 24 shows a fourth embodiment of the manual transmis-sion.

Fig. 1 shows a schematic illustration of a manual transmission ac-cording to a first embodiment of the invention. A drive shaft 1 carries two hollow is shafts 2, 3 which are fitted with gear wheels 4, 5 and 6, 7. The hollow shafts 2, 3 can respectively be coupled via a friction clutch 8 and 9 to the drive shaft 1 in a fric-tionally engaged manner. A respective selector sleeve 10 and 11 is mounted on both hollow shafts 2, 3 in a torsion-proof and axially adjustable manner. The selec- tor sleeves 10, 11 which rotate with the hollow shafts 2, 3 are respectively sur-rounded by a ring 12, which is torsion-proof with respect to a housing (not shown) of the manual transmission, but is axially movable.

Fig. 2 shows the ring 12 in a perspective view. Several coulisses 46 are recessed in a circumferential area of the ring 12. Preferably, three such couliss-es 46 are evenly distributed over the circumference of the ring 12. Each coulisse 46 comprises two sections 49, 50 extending in the circumferential direction and a heli-cal section 51 which connects said two sections.

Relating to Fig. 1 again1 the two rings 12 are surrounded on their part by a gear wheel 13 which is disposed coaxially to the drive shaft 1. The gear wheel 13 is rotatable about the ring 12 associated therewith and engages by means of cams 14 in the coulisses 46 of the ring 12.

Balls 15 are retained in boreholes of the gear wheel 13, which is shown in Fig. 3 in an axial top view. The balls 15 respectively touch a pressure ring 16 on the one hand, whose outline is shown in Fig. 3 with the broken line, and an axially movable ring 17 on the other hand, which respectively extends about one of the hollow shafts 2, 3 and is supported by a roller bearing 18 on the plates 19 of the friction clutch 8 and 9 on the side of the hollow shaft. As is illustrated, the pressure ring 16 can be a separate component on the housing of the manual transmission. It S can also be an integral component of the wall of the housing.

Fig. 4 shows the pressure ring 16 in an axial top view which is analo-gous to Fig. 3. Several ramps 68 are formed in the surface of the pressure ring 16 in form of arc-shaped grooves which are concentric to the drive shaft I extending through the opening of the pressure ring. Each ramp 68 comprises a central section 69 of constant depth in which a balI 15 is movable in the circumferential direction around the drive shaft 1. In the outer sections 70, which are adjacent to the central section 69 on both sides, the depth of the groove respectively continuously de-creases to the outside, so that the balls are respectively guided therein on helical orbits with respectively opposite chirality. The gear wheel 13, the balls 15 and the pressure ring 16 can be regarded as a rotation-translation converter module 71 of first type. They respectively convert a rotation of the gear wheel 13 into a translatory motion of the balls 15 or plates 19 of the friction clutch 8 and 9.

Fig. 1 shows the gear wheel 13 in a neutral position, from which it is adjustable in opposite directions. The balls 15 are respectively situated in the middle of their ramp 68. During each rotation of the gear wheel 13 from the neutral posi-tion, it passes through an angular interval at first in which the balls 15 do not leave the central section 69 of the ramps 68 and are therefore not deflected in the axial direction. When entering an outer section 70, the balls 15 are increasingly pressed by the pressure ring 16 against the plates 19 and finally push the same in frictionally engaged contact with plates 20 of the friction clutches 8 and 9 on the side of the drive shaft.

In the coulisse 46 of the ring 12, the neutral position corresponds to an engagement of the cam 14 on the boundary between the sections 49, 51, as labeled in Fig. 2 by the dashed outline of the cam 14. From there, the cam 44 pass-es the section 49 extending in the circumferential direction during a rotation of the gear wheel 13 in a first direction of rotation, so that the friction clutch 8 and 9 closes when the balls 15 leave their central section 69, without the ring 12 and the selector sleeve 10 or 11 that are controlled thereby moving in the axial direction. In the case of rotation of the gear wheel 13 in the opposite second direction of rotation, the cam 14 passes through the helical section 51 at first, so that the ring 12, and together with said ring the selector sleeve 10 and 11, is axially adjusted from the neutral po-sftion to said second direction. In the manner as known from conventional locking synchromesh devices, the selector sleeve 10 and 11 presses at first against the synchronized disc 21 (Fig.1) and brings the same into frictional contact with a gear wheel 22 and 23 in order to engage the same in a selector toothing 24 of the gear wheel 22, 23 when it is synchronized with the hollow shaft 2 and 3 and to thus cou-ple it in a torsion-proof manner to the hollow shaft 2 and 3. When the selector sleeve 10 and 11 has engaged in the selector toothing 24, the cam 14 reaches the section 50 of the coulisse 46 extending in the circumferential direction, so that the selector sleeve 10 and 11 is no longer displaced any further when the balls 15 leave the central section 69 of the ramps 68 and start to deflect the plates 19.

The transmission comprises two auxiliary shafts 25, 26. The auxiliary shaft 25 carries a fixed gear 27 which meshes with the gear wheel 22 and forms a gear set therewith for a fifth gear, a fixed gear 28 which meshes with a gear wheel 23 and forms a gear set for a second gear therewith, and an idler gear 29 which meshes with the gear wheel 5 and forms a gear set therewith for a first gear, and an idler gear 30 which meshes with a gear wheel 7 and forms a gear set therewith for a fourth gear, a selector sleeve 31 which is displaceable from its neutral position shown in Fig. 1 in opposite directions in order to respectively couple the idler gear 29 or the idler gear 30 in a torsion-proof manner to the auxiliary shaft 25 and to thus preselect either the first or the fourth gear, and an output pinion 32. The auxiliary shaft 26 carries an idler gear 33 which meshes with the gear wheel 4 and forms a gear set therewith for a third gear, an idler gear 34 which meshes with the gear wheel 6 and forms a gear set therewith for a sixth gear, a selector sleeve 35 which is displaceable from the neutral position as shown in Fig. 1 in opposite directions in order to respectively couple one of the idler gears 33, 34 in a torsion-proof manner to the auxiliary shaft 26 and to thus preselect either the third or the sixth gear, and an output pinion 36. Both output pinions 32, 36 mesh with a differential gear (not shown in Fig. 1).

A control mechanism 37 for the gear selection is highlighted in Fig. I from the aforementioned components for the purpose of befter clarity of the illustra- tion and is shown in Fig. 5 in a perspective view. The control mechanism 37 com-prises two selector shafts 38, 39 which are aligned along the same longitudinal axis parallel to the shafts 1, 25 and which are rotatably mounted around the axis 40.

Fig. 6 shows the control mechanism 37 in a sectional view along the axis 40.

S In the case of the embodiment that is considered here by way of ex-ample, the selector shaft 39 is a hollow shaft which extends in the direction of axis only over a part of the control mechanism 37 and in which the selector shaft 38 formed as a solid shaft is accommodated. Altematively, the two selector shafts can also be over-mounted on one side, or two hollow shafts can be concerned which are to pushed onto a common carrier.

Each selector shaft 38, 39 carries one or two radially protruding se-lector fingers 41, 42, 43. In Fig. 1, a selector finger 41 of the selector shaft 38 is shown in engagement with a shift fork 58, which is rigidly connected to a selector fork 62 acting on the selector sleeve 31. A second shift fork 52 is connected to a selector fork 57 acting on the selector sleeve 35.

The selector shafts 38, 39 are not twistable against each other, but are mutually movable along the axis 40. For this purpose, a pin anchored on the selector shaft 39 can engage in a longitudinal groove of the selector shaft 38.

The shift forks 52, 58 are substantially plate-shaped with a narrow side facing the axis 40, in which two sections 53 are formed, i.e. one for accommo- dating the selector fingers 41, 42 of the selector shaft 38 and the other for accom-modating the selector finger 43 of the selector shaft 39. A further cam follower 54 with a single section 53 can be arranged in order to also accommodate the selector finger 43. While the shift forks 52, 58 are used for preselectiori among the six for-ward gears, the cam follower 54 is provided for the preselection of the reverse gear.

A gear set provided for this purpose is not shown in Fig. 1, but the person skilled in the art knows possibilities to house such a gear set.

The two selector fingers 41, 42 span a different angle with respect to the axis 40 than the shift forks 52, 58, so that the two never engage simultaneously in the shift forks 52, 58.

The selector shafts 38, 39 are respectively surrounded by shift sleeves 55 and 56, which are arranged in a torsion-proof manner with respect to a housing of the transmission (not shown). In order to prevent rotation of the shift sleeves 55, 56, but to simultaneously allow a translatory motion along the axis 40, the shift sleeves 55, 56 are respectively provided with one longitudinal groove 61 (only shown for the shift sleeve 56 in Fig. 2) into which a finger 63 engages which is fixedly attached to the housing. Several fingers 64 of the shift sleeves 55, 56, which fingers are directed radially to the inside, engage in a circumferential groove 65 of the selector shaft 38 and 39 (see Fig. 1) in order to transmit a translatory motion of the shift sleeves 55, 56 onto the selector shafts 38, 39. but to simultaneously permit a rotation of the selector shafts 38, 39 about the axis 40.

A coulisse 46, which is attached to the shift sleeves 55, 56 and is al-so arranged in this case as a groove, respectively comprises a helical section 51 and, on both ends of the helical section 51, sections 49, 50 extending in the circum-ferential direction around the axis 40. In Fig. 2, the coulisses 46 are mostly hidden in the drums 66 and 67, which respectively carry a cam 44 which cooperates in an interlocking fashion with the coulisse 46. The drums 66, 67 are axially immobile, but are rotatable about the axis 40 by engagement of a respective one of a threaded screw 48 driven by a servomotor 47 on a gear wheel 45 which is connected in a torsion-proof manner to the drum 66 and 67. The side walls of the drums 66, 67 are cut out over a large area in order to allow the finger 63 to pass through without im-pairing the rotation of the drums 66, 67.

Each drum 66 and 67 thus forms a rotation-translation converter module 72 of a second type together with the sleeve 55, 56, in the coulisse 46 of which its cam engages, which module converts the rotation of the servomotor 47 into a translatory motion of the selector shaft 38 and 39 and the selector sleeve 35 or 31 which is respectively coupled thereto by the selector finger 41, 42 or 43.

Analogously thereto, the gear wheels 13 and the rings 12, in whose coulisses 46 the cams 44 of the gear wheels 13 engage, can be regarded as rota-tion-translation converter modules 73. The functionality of the converter modules 72 and 73 is analogous in the respect that a rotation from the neutral position, depend-ing on whether it guides the cam 44 to the section 50 or the section 51, either leads to no translatory motion or to the immediate occurrence of the translatory motion, whereas in the converter modules 71 of the first type the rotation does not produce any translatory motion at first as long as the balls 15 m9ve in the central sections 69 of the ramp 68, but once the balls 15 enter the outer sections 70, a translatory mo- tion is driven in the same direction in both rotational directions. Driven by a continu-ous rotation of the servomotor 47, a sequential sequence of the movements of the selector sleeves 101 11, 31, 35 is achieved on the one hand and the friction clutches 8, 9 on the other hand as a result of the different divisions in sections of the couliss-es 46 and the ramps 68, i.e. the modules 71, 72, 73 which are rotationally coupled to each other by the engagement of the gear wheels 45, 13 jointly form a sequenc- ing mechanism in order to successively control the preselection of a gear by dis-placement of one of the selector sleeves and the subsequent engagement of the preselected gear by closing the friction clutch 8 or 9.

In the illustration of Fig. 1, the transmission is idling, and the hollow shafts 2, 3 are twistable against the drive shaft I, and the idler gears 29, 30 and 33, 34 are twistable against the auxiliary shafts 25 and 26. In order to engage a first gear in the transmission, a torque flow must be produced from the drive shaft 1 to the differential gear via the gears 5, 29. The left servomotor 47 is actuated for this purpose in a first step in order to twist the left gear wheel 45 that meshes therewith in such a way that the cam 44 on the left drum 66 passes through the helical section 51 of the coulisse 46 and displaces the selector shaft 38 along the axis 40 to the left. The selector finger 41 entrains the selector sleeve 31 via the shift fork 58 and thus couples the idler gear 29 to the auxiliary shaft 25. Fig. 7 shows the resulting configuration of the control mechanism 37 partly in a top view in the direction of the two cams 44 (wherein the portion of the drums 66, 67 that carries the cams 44 is cut away in order to show the coulisse 46), and partly in a sectional view in the planes of the shift forks 52, 58.

The selector sleeve 31 and the coupling of the idler gear 29 to the auxiliary shaft 25 produced by the displacement of the sleeve are not shown in Fig. 7 because they are based on the locking synchromesh principle which is known to the person skilled in the art. A synchronized disc 21 conventionally blocks the ad- vancement of the selector sleeve 31 for such a time until the idler gear 29 is syn- chronized by friction with the auxiliary shaft 25. The cam 44 can advance to the p0-sition shown in Fig. 7 only when the synchronized disc 21 releases the path to the selector sleeve 31 in order to latch into the idler gear 29.

The left gear wheel 13 is also twisted out of its neutral position to- gether with the left gear wheel 45, but not to such an extent that an axial displace-ment occurs of the balls 15 caught in the gear wheel 13. The friction clutch 8 thus remains open. Although the selector sleeve 3lis latched into the idler gear 29 in an interlocking manner, no torque is yet transmitted.

As a result of a further rotation of the left servomotor 47, the cam 44 (as shown in Fig 8) reaches a limit stop at the end of section 50 of the coulisse 46 While the cam 44 passes through the section 50, the left gear wheel 13 also contin-ues to rotate, and its balls 15 are axially deflected on the ramp 68. As a result, the plates 19, 20 of the left friction clutch 8 are gradually pressed against each other, the friction clutch 8 closes, and the torque flow in the first gear is established.

As is shown, the balls 15 cooperate with the ramps 68 in an interlock-ing fashion in the same manner as the cams 44 with the coulisses 46, so that the balls can generally also be regarded as cams and the ramps 68 as the coulisses that guide them, which are substantially distinguished from the coulisses 46 only by the shape of the path guided by them.

In order to change to the second gear, the right servomotor 47 is ac-tivated. It twists the right gear wheel 45, so that the cam 44 of the drum 67 passes through the section 49 of the coulisse 46. Since the section 49 extends in the cir-cumferential direction, the actuating rod 39 is not moved by the rotation. The gear wheel 13 rotates together with the gear wheel 45, and its cams 14 pass through the section 51 in the coulisse 46 of the ring 12 at first, so that the selector sleeve 10 latches into the idler gear 22. In the position as shown in Fig. 9, the rotation of the co-rotating right gearwheel 13 has progressed to such an extent that the cams 14 are situated on the ring 12 in the section 50 and the balls 15 are slightly axially de-flected so that the plates 19, 20 of the friction clutch 9 begin to touch each other.

While the right gear wheel 45 is twisted beyond the position as shown in Fig. 9 until the clutch 9 closes, the left gear wheel 45 is simultaneously rotated in the opposite direction, so that the cam 44 of the drum 66 returns to the boundary between the sections 50, 51. In this state shown in Fig. 10, the torque flows in the second gear via the gear wheel 23 and the fixed wheel 28, and the clutch 8 is open again. The first gear is still preselected.

If the left gear wheel 45 (as shown in Fig. 11) is twisted further back, the cam 44 passes through the section 51 again, the selector shaft 38 returns to its position shown in Fig. , and the selector sleeve 31 is situated in its neutral position again between the idler gears 29, 30. The preselection of the first gear is thus relin-quished. The position of the right gear wheel 45 does not change in the meantime so that the second gear is still engaged in Fig. 11.

In Fig. 12, the selector shafts 38, 39 are twisted about the axis 40, so that the selector finger 41 engages at nothing and instead the selector finger 43 of the selector shaft 39 engages in the shift fork 58 and the selector finger 42 of the selector shaft 38 engages in the shift fork 52.

A renewed forward rotation of the left gear wheel 45 in which the cam 44 (as shown in Fig. 13) passes through the helical section 51 again produces an axial displacement of the left selector shaft 38, but in this case the shift fork 52 and the selector sleeve 35 which is coupled thereto via the selector fork 57 are en-trained on the auxiliary shaft 26 and brought into interlocking engagement on the idler gear 33. The third gear is thus preselected. Since the friction clutch 9 is still closed and the friction clutch 8 is still open it has not yet been engaged.

In order to engage the third gear (as shown in Fig. 14), the right gear wheel 45 is twisted back to the initial position already shown in Fig. 1 in which the right friction clutch 9 is open, while simultaneously the left friction clutch 8 is closed by twisting of the left gear wheel 45 close to the. end of the section 50.

The position of the left gear wheel 45 is unchanged in Fig. 15, so that the friction clutch 8 remains closed and the third gear is engaged. The cam 44 is again situated at the boundary between the sections 49, 51 on the right gear wheel 45.

The cam 44 is moved through the section 51 in Fig. 16 by further ro-tation of the right gear wheel 45, and the selector shaft 39 is deflected to the right.

The shift fork 58, which is coupled thereto by the selector finger 43, is deflected to the right with said shaft, and the selector sleeve 31 is in interlocking engagement with the gear wheel 30.

In order to engage the fourth gear, the friction clutch 9 needs to be closed and the friction clutch 8 needs to be opened. This occurs again by twisting of the mutually coupled gear wheels 45, 13 on the left and right side of the transmis-sion, so that (as shown in Fig. 17) the right cam 44 reaches a position close to the end of section 50, while the left cam 44 is situated on the boundary between the sections 50, 51.

In Fig. 18, the left gear wheel 45 is further twisted back, so that the left cam 44 is situated between the sections 49, 51 again and the shift fork 52 cow pled to the left selector shaft 38 is situated in the neutral position again. The fourth gear is engaged and the preselection of the third gear is relinquished.

Fig. 19 shows the right gear wheel 45 rotated to a position again in which the friction clutch 9 is open, while the cam 44 is situated on the left gear wheel 45 close to the end of the section 49. The friction clutch 8 is closed in this position and the selector sleeve 10 couples the hollow shaft 2 to the gear wheel 22 so that a fifth gear is engaged in which the torque flow extends via the gear wheel 22 to the fixed gear 27 of the auxiliary shaft 25.

In Fig. 20, the left gear wheel 45 continues to remain in the stop posi-tion in which the friction clutch 8 is closed, while the cam 44 is again situated on the right gear wheel 45 between the sections 49, 51 and the shift fork 58 holds the se-lector sleeve 31 in its neutral position so that the preselection of the fourth gear is cancelled.

In order to engage the sixth gear, the selector shafts 38, 39 are twisted at first again about the longitudinal axis 40, so that the selector finger 41 engages again on the shift fork 58 and the selector finger 43 on the shift fork 52.

The state shown in Fig. 21 in which the sixth gear is engaged is subsequently reached by the rotation of the right gear wheel 45 until the cam 44 is close to the end of the section 50 with simultaneous opening of the friction clutch 8. The torque flow extends via the gear wheels 6 and 34 to the auxiliary shaft 26.

Fig. 22 shows a second embodiment of a double clutch transmission in accordance with the invention. The control mechanism 37 is identical to the one of Figs. I to 3 and will therefore not be shown again. The difference from the transmission of Fig. 1 is that the fixed gear 28 is moved to the auxiliary shaft 26.

This has no influence on the sequence of the shifting processes as described above.

In the embodiment of Fig. 23, the fixed gears of one of the main shafts. i.e. the fixed gears 6 and 7 of the main shaft 3, are merged into a single gear 6/7 which meshes with the idler gears 30, 34 of the auxiliary shafts 25, 26 and thus simultaneously belongs to the gear sets of the fourth and sixth gear. Although this allows a reduction in the weight, this still does not make the transmission substan-tially more compact because the distance between the mutually opposite ends of the main shafts 2, 3 are still determined by the need for space of the selector sleeve 31 and the idler gears 29, 30 on the auxiliary shaft 25 which is still unchanged with respect to the embodiment of Fig. 1.

IS In the embodiment of Fig. 24, the fixed gears 4, 5 of the main shaft 2 are jointly merged into a gear 4/5, which simultaneously belongs to the gear sets of the first and the third gear. A reduction in the length of all shafts in comparison with the previously discussed embodiments is possible in this case.

In the embodiments of Fig. 23 and 24, the fixed gears 27, 28 are dis-tributed among the two auxiliary shafts 25, 26. As in the case of Fig. 1, they could be both attached to the auxiliary shaft 25 or, as not shown in the drawings, they could be both attached to the auxiliary shaft 26.

It is understood that the above detailed description and drawings rep- resent specific exemplary embodiments of the invention, but that they are only in- tended for illustration and shall not be construed as limiting the scope of the inven- tion. Various modifications of the described embodiments are possible without de- parting from the scope of the following claims and their equivalent range. In particu- lar, this description and the drawings also provide embodiments which are not men-tioned in the claims. Such features can also occur in combinations other than those specifically disclosed herein. The fact that several such features are mentioned in the same sentence or in any other manner of textual context does not justify the conclusion that they can only occur in the specifically disclosed combination. In-stead, it must be assumed in principle that individual features can be omitted or modified in the case of several such features in so far as the functionality of the invention is thus not placed in doubt.

List of reference numerals 1 Drive shaft 2 Main shaft 3 Main shaft 4 Gear wheel Gear wheel 6 Gear wheel 7 Gear wheel 8 Friction clutch 9 Friction clutch Selector sleeve 11 Selector sleeve 12 Ring 13 Gearwheel 14 pin Ball 16 Pressure ring 17 Ring 18 Roller bearing 19 Plate on the side of the hollow shaft Plate on the side of the drive shaft 21 Synchronized disc 22 Gear wheel 23 Gear wheel 24 Selector toothing Auxiliary shaft 26 Auxiliary shaft 27 Fixed gear 28 Fixed gear 29 Idler gear Idler gear 31 Selector sleeve 32 Output pinion 33 Idler gear 34 Idler gear Selector sleeve 36 Output pinion 37 Control mechanism 38 Selector shaft 39 Selector shaft Axis 41 Selector finger 42 Selector finger 43 Selector finger 44 Cam Gear wheel 46 Coulisse 47 Servomotor 48 Threaded screw 49 Section of coulisse Section of coulisse 51 Section of coulisse 52 Cam follower 53 Section 54 Cam follower Shift sleeve 56 Shift sleeve 57 Selector fork 58 Cam follower 59 Longitudinal groove Finger 61 Longitudinal groove 62 Selector fork 63 Finger 64 Finger Groove 66 Drum 67 Drum 68 Ramp 69 Central section Outer section 71 Rotation-translation converter module 72 Rotation-translation converter module 73 Rotation-translation converter module

Claims

CLAIMS: 1. A double clutch transmission, comprising a drive shaft (1), a first main shaft (2) which can be coupled via a first friction clutch (8) to the drive shaft (1), a second main shaft (3) which can be coupled via a second friction clutch (9) to the drive shaft, and a plurality of gear sets which respectively comprise a gear (4, 5, 22, 6, 7, 23) on the drive side on one of the main shafts (2, 3) and a gear (33, 29, 27, 34, 30, 28) on the output side on at least one first auxilia-ry shaft (25) which meshes with the gear (4, 5, 22, 6, 7, 23) on the drive side, wherein at least two of the gear sets (5, 29; 7, 30) comprise idler gears (29, 30) which can be coupled from a similar, double-acting first selector sleeve (31) to the first auxiliary shaft (25), of which one (29) of the idler gears meshes with a fixed gear(S) of the first main shaft (2) and the other one (30) meshes with a fixed gear (7) of the second main shaft (3), and at least one first gear set (22, 27) switched to the main shaft side comprises an idler gear (22) on one of the main shafts (2), which can be coupled by a second selector sleeve (10) to the main shaft (2), and a fixed gear (27) on the or one auxiliary shaft (25).
2. A double clutch transmission according to claim 1, wherein the second se-lector sleeve (10) is arranged between the idler gear (22), by means of which it can be coupled to the main shaft (2), and the friction clutch (8) which is associated with said main shaft (2).
3. A double clutch transmission according to one of the preceding claims, wherein at least one gear set (5, 29) comprises an idler gear (33) which can be coupled by a third selector sleeve (35) to a second auxiliary shaft (26) and which meshes with a fixed gear (4) of the first main shaft (2).
4. A double clutch transmission according to claim 3, further comprising a gear set (6, 34) which comprises an idler gear (34) which can be coupled by the double-acting third selector sleeve (35) to the second auxiliary shaft (26) and a fixed gear (6) on the second main shaft (3).
5. A double clutch transmission according to one of the preceding claims, fur-ther comprising a second gear set (23, 28) which is switched on the side of the main shaft and comprises an idler gear (23) on a main shaft (3) that dif-fers from the one (2) of the first gear set (22, 27) which is switched on the side of the main shaft and which can be coupled by a fourth selector sleeve (11) to said other main shaft (3), and a fixed gear (28) on one of the auxiliary shafts (25).
6. A double clutch transmission according to one of the preceding claims, wherein the gear sets whose gears (4, 5, 22) on the drive side are situated on the first main shaft (2) represent odd-numbered gears of the transmis-sion, and the gear sets whose gears (6, 7, 23) on the drive side are situated on the second main shaft (3) represent even-numbered gears.
7. A double clutch transmission according to one of the preceding claims, wherein at least one further gear with an intermediary gear ratio is situated between gears which are represented by gear sets (5, 29; 7, 30) that are shifted by the same double-acting selector sleeve (31).
8. A double clutch transmission according to one of the preceding claims, wherein at least one of the main shafts (2, 3) carries a fixed gear (4/5, 6/7)
9. A double clutch transmission according to one of the preceding claims, comprising a first sequencing mechanism (12-17, 44-46) for converting a continuous drive movement into a movement of one of the selector sleeves (31) from a neutral position to a shifting position coupling the idler gear (29) of one of the gear sets (5, 29) to its shaft (25) and, after reaching the shifting position, to a closing movement of the first friction clutch (8) driving the gear set (5, 29).
10. A double clutch transmission according to claim 9, wherein the sequencing mechanism (12-17, 44-46) comprises a first and second rotation-translation converter module (71; 72), wherein the converter modules (71; 72) respec-tively comprise a drive part (13; 66, 67) which is pivotable about an axis and.an output part (17; 38, 39) driven in translatory motion by a pivoting move-ment of the drive part (13; 66, 67), wherein the drive parts (13; 66, 67) are rotationally coupled and the output part (17) of the first converter module (71) cooperates with the first friction clutch (8) and the output part (38, 39) of the second converter module (72) cooperates with the one selector sleeve (31).
11. A double clutch transmission according to claim 10, wherein at least one of the converter modules comprises a coulisse (46) and a cam (44) which co-operates with the coulisse (46) in an interlocking fashion, the cam (44) and the coulisse (46) are mutually pivotable about the axis (40), and the coulisse (46) comprises at least one section (51) extending helically about the axis and at least one section (49, 50) extending in the circumferential direction.
12. A double clutch transmission according to claim 10 or 11, wherein the se- quencing mechanism (12 to 17, 44 to 46) comprises a third rotation-translation converter module (73), wherein the selector sleeve (31) actuated by the second converter module (72) is one of the double-acting selector sleeves (31, 35) and the third converter module (73) actuates the second se-lector sleeve (10).
13. A double clutch transmission according to one of the claims 9 to 12, further comprising a second sequencing mechanism (12-17, 44-46) for converting a continuous drive movement into a movement of one of the selector sleeves (31, 35) from its neutral position to a shifting position coupling the idler gear (30) of one of the gear sets (7, 30) to its shaft (25) and, after reaching the shifting position, to a closing movement of the second friction clutch (9) driv-ing said gear set.
14. A double clutch transmission according to claim 13, comprising a selection mechanism which in a first state connects the first selector sleeve (35) to the first sequencing mechanism (12-17, 44-46) and the third selector sleeve (31) to the second sequencing mechanism (12-17, 44-46), and which in a second state connects the first selector sleeve (35) to the second sequencing mechanism (12-17, 44-46) and the third selector sleeve (31) to the first se-quencing mechanism (12-17, 44-46).