GB2525300A

GB2525300A - A manual transmission

Info

Publication number: GB2525300A
Application number: GB1503701.3A
Authority: GB
Inventors: Christian Rubsam
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2014-03-10
Filing date: 2015-03-04
Publication date: 2015-10-21
Also published as: CN104913052B; GB201503701D0; CN104913052A; DE102014003239A1

Abstract

A manual transmission comprises a first and a second selector sleeve 31, 35 which are movable in an axial direction on a shaft 25, 26 between a neutral position and an engaged position in which they couple an idler gear 29, 33 to the shaft 25, 26. A first and a second selector fork 57, 62 act on the selector sleeves 31, 35 in order to control their axial movement. A locking element 58 locks the selector sleeves 35, 31by preventing movement of a coupling arm 43 which is connected to the first and the second selector fork 57, 62 via a first and second joint 44. The arm 43 comprises a pivotal point 54 between the joints 44 on which an actuating element 55 acts that is movable in an axial direction when cams 56 are rotated. The locking element 58 has notches 61 which engage in notches 59, 60 on the selector forks 62 so as to block movement of the forks 62. Twisting of the locking element 58 disengages the notches 59, 60, 61 which allow movement of the forks 62.

Description

s A manual transmission

Description

The present invention relates to a manual transmission, comprising a first and a second selector sleeve, whi:h are respectively movable in the axial direc-tion on a shaft of the manual transmission between a neutral position and at least one shifting position in which they couple an idler gear to the shaft, and comprising a first and second selector fork which act on the first and second selector sleeve in IS order to control their axial movement. Such manual transmissions are generally known and used in motor vehicles.

In a manual transmission, the driver actuates a shift lever for chang-ing gears and the force exerted by the driver is transmitted to the selector sleeves in form of a translatory movement via a Bowden cable or the like. If such a transmis-sion is to be shifted in an automated fashion by means of a servomotor for example, a reduction gear is generally needed in order to generate the force required for dis- placing the selector sleeve. If several selector sleeves need to be driven by servo-motors, said servomotors and their gears require a far from insubstantial amount of space and cause considerable costs.

It is an object of the present invention to provide a manual transmis-sion which enables automated shifting operation with a low amount of effort.

This object is achieved in an embodiment of the invention by a man-ual transmission with a first and second selector sleeve, which are respectively movable in the axial direction on a shaft of the manual transmission between a neu-tral position and at least one shifting position in which they couple an idler gear to the shaft, a first and second selector rork which act on the first or the second selec-tor sleeve in order to control their axial movement, a first locking element for locking the first selector sleeve, a second locking element for locking the second selector sleeve, a coupling arm which is connected to the first and the second selector fork via a first and second joint, and comprises a pivotal point between the joints on which an actuating element acts which is movable in the axial direction. By locking a respective selector sleeve by means of a locking element, the coupling arm -when displaced by the acting actuating element -is forced to pivot about an axis on the locked selector sleeve and to thus displace the respective other selector sleeve. As a result, a single linearly movable actuating element is sufficient in order to control the movements of two selector sleeves.

The locking elements can be rigidly connected and be movable be-tween a position locking the first selector sleeve and a position locking the second selector sleeve.

In particular, the first locking element, which can be rod-shaped for is example, can be pivotable about a longitudinal axis between a position locking the first selector sleeve by engagement in a recess of the first selector fork and a re-lease position in which a recess of the first locking element faces the recess of the first selector fork. The mutually facing recesses of locking element and selector fork do not block the displacement of the respective selector sleeve, so that shifting can be performed by simple rotation of the locking element between the locked and the movable state of the selector sleeve. This can also apply analogously to the second locking element.

When the locking elements are connected among each other into a single locking body, a selector sleeve and selector fork can be locked simultaneous-ly. by a single rotation of said locking body and the locking of the other selector sleeve can be released. It is also possible to simultaneously lock or release more than two selector sleeves/selector forks.

According to one embodiment, the actuating element is a two-arm lever which can be pivoted about the pivotal point, of which a first arm is coupled to a first linear actuator driving a movement in the direction of the shaft and a second arm is coupled to a second linear acluator driving a movement in the direction of the shaft. Such an actuating element is especially suitable for use in a twin-clutch man- ual transmission, in which the selector sleeve can be used to engage a gear asso- ciated with a first friction clutch by means of a first linear actuator and a gear asso-ciated with a second friction clutch by means of the second linear actuator.

In order to expand the possibilities for shifting, a carriage can be movable in said latter embodiment along the coupling arm between an idle position and a position coupling a third selector fork to the coupling arm. The coupling to the other selector forks can be independent of the position of the carriage, or the cou-pling to one of the two other selector forks can be released in the position coupling the third selector fork.

In order to control the movement of the carriage, a cam of the car- riage can interact with a stationary coulisse which comprises a section which is par-allel to the shaft and a section which is oriented in an oblique manner in relation to the shaft, As long as the cam engages in the section parallel to the shaft, a move-ment of the actuating element has no influence on the position of the carriage. If the cam engages in the oblique section, a movement of the coupling arm in the direc-tion of the shaft leads to a displacement of the carriage along the coupling arm.

As already mentioned above, the manual transmission can be ar-ranged as a twin-clutch transmission with a first and a second fiction clutch. In this case, the first linear actuator and the first friction clutch can jointly comprise a first actuating drive in order to successively drive a movement of the selector sleeves at first and subsequently a closure of the friction clutch, or an opening of the friction clutch at first and then a movement of the selector sleeves. Accordingly, the second friction clutch and the second linear actuator can jointly comprise a second actuat-ing drive.

The actuating drive is a rotational drive in at least one of the linear actuators, preferably in both thereof, whose rotational movement is converted into a 3O translatory movement of the linear actuator in that the linear actuator comprises a coulisse and a cam interacting in an interlocking fashion with the coulisse, which -driven by the actuating drive -are pivotable relative to one another about an axis.

Said coulisse can comprise at least one section extending helically around the axis.

Sections can be provided which are adjacent to the ends of the heli-cal section and extend in the circumferential direction around the axis in order to enable a rotation of the cam and coulisse against each other even without simulta-neous linear displacement. Such a section extending in the circumferential direction is especially useful in order to enable continued running of the actuating drive after the selector sleeve has reached a gear position, by means of which the friction clutch can be closed.

The axis about which the coulisse extends can extend through a se-lector shaft, on which the selector fork is guided which is movable by the rotation of coulisse and cam against each other.

The selector shaft can be pivoted in its entirety about the axis relative to the selector fork and carry a gear on which the actuating drive acts in order to IS pivot the selector shaft.

The coulisse can appropriately be a groove that is radially open to the outside, fixed to the selector shaft ani therefore pivotable together with said shaft.

The selector fork can carry an arm extending along the selector shaft The engagement of an arm of the actuating element between the arm of the selector fork and the selector shaft secures the cam of the actuating element in a simple manner in the radial direction in the groove.

The aforementioned coupling arm that connects the first and second selector fork can further be linked in an articulated manner to the arm of the selec-tor fork.

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 an embodiment of the present invention; 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 selector forks of the transmission and a control mechanism for displacing the selector forks; Fig. B shows a selector drum of the control mechanism in a view on an enlarged scale; Fig. 7 shows the selector drum and an arm of an actuating element acting on said drum; Fig. 8 shows a schematic top view of the control mechanism and parts of the transmission in the neutral position; Fig. 9 shows a top view analogously to Fig. 8 with preselect-ed first gear; Fig. 10 shows a top view with engaged first gear; Fig. 11 shows a top view after shifting to the second gear; Fig. 12 shows a top view with preselected third gear; Fig. 13 shows a top view with preselected fourth gear, and Fig. 14 shows a perspective view of a control mechanism for controlling three selector sleeves.

Fig. 1 shows a schematic view of a manual transmission according to a first embodiment of the invention. A drive shaft 1, which is typically permanently connected to a drive engine of a motor vehicle for example, carries two hollow shafts 2. 3 which are equipped with gear wheels 4 and 6. The hollow shafts 2, Scan respectively be coupled by a friction clutch 8 and 9 in a frictionally engaged fashion to the drive shaft 1. A respective selector sleeve 10 and 11 is mounted in a torsion-proof and axially adjustable manner on the two hollow shafts 2, 3. The selector sleeves 10, 11 which rotate with the hollow shafts 2, 3 are respectively surrounded by a ring 12 which is torsion-proof with respect to a housing (not shown) of the manual transmission, but which 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. Three such coulisses 46 are preferably evenly distributed over the circumference of the ring 12. Each coulisse 46 is comprises two sections 49, 50 extending in the circumferential direction and a heli- cal section 51 which connects said two sections. The angular extension of the sec-tion 49 is as large as that of the sections 51, 50 combined.

Relating to Fig. 1 again, the two rings 12 are surrounded by a gear wheel 13 coaxial to the drive shaft 1. The gear wheel 13 is respectively rotatable about the associated ring 12 and engages by means of the pin-like cam 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, which plates are connected in a torsion-proof manner to the adjacent hollow shaft 2 or 3. As is illustrated, the pressure ring 16 can be a sepa- rate component on the housing of the manual transmission. It can also be an inte-gral component of the wall of its 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 1 extending through the opening of the pressure ring. Each ramp 68 comprises a central section 69 of constant depth in which a ball 15 is movable in the circumferential direction around the drive shaft 1 on an arc-shaped orbit. In the outer sections 70, which are adjacent to the central section 69 on both sides, the depth of the groove respective-ly continuously decreases 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 linear actuator of a first type. They respectively convert a rotation of the gear wheel 13 into a translatory motion of the balls 1501 plates 19 of the friction clutch B and 9.

Fig. 1 shows the gear wheel 13 in a neutral position, from which it is pivotable in opposite directions about the shaft 1. The balls 15 are respectively situ-ated in the middle of their ramp 68 in this neutral position. During each rotation of the gear wheel 13 from the neutral position, it passes through an angular interval at is first in which the balls 15 do not leave the central sections 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 B and 9 on the side of the drive shaft.

In the neutral position, the cam 14 is situated in the coulisse 46 of the ring 12 on the boundary between the sections 49, 51, as indicated in Fig. 2 by the dashed outline of the cam 14. From there, the cam 44 passes the section 49 ex-tending in the circumferential direction during a rotation of the gear wheel 13 in a first direction of rotation, so that the friction clutch B 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, originat-ing from the neutral position, 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 ad-justed. In the manner as known from conventional locking synchromesh devices, the selector sleeve 10 or 11 presses at first against a synchronized disc 21 (Fig.1) and brings the same into frictional contact with an idler gear 22 and 23 in order to engage the same in a selector toothing 24 of the idler gear 22, 23 when it is syn- chronized with the hollow shaft 2 and 3 that carries said idler gear, and to thus cou-ple it in a torsion-proof manner to the hollow shaft 2 and 3. When the selector

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sleeve 10 or 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 or 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 idler gear 22 and forms a gear set therewith for a fifth gear, a fixed gear 28 which meshes with an idler gear 23 and forms a gear set for a second gear therewith, and an idler gear 29 which meshes with the fixed gear 4 and forms a gear set therewith for a first gear, and an idler gear 30 which meshes with a fixed gear 6 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 IS 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).

Of the fixed gears 4, 6 on the hollow shafts 2, 3 which are used for two gears each, one or both can be replaced by two fixed gears of different diame-ter, of which one meshes with the idler gear 29 or 30 of the auxiliary shaft 25 and the other with the idler gear 33 or 34 of the auxiliary shaft 26.

A control mechanism 37 for the gear selection has been omitted in Fig. 1 for the purpose of better clarity of the illustration and is shown in Fig. 5 in a perspective view instead. The control mechanism 37 comprises two selector shafts 38, 39 which are aligned in parallel to the shafts 1, 25, 26 and which are pivotable about an axis parallel to the shafts. The selector shafts 38, 39 respectively carry a gear wheel 45 at opposite ends. The gear wheel 45 on the selector shaft 38 meshes the left gear wheel 13 of Fig. 1, which means the gear wheel 13 whose rotation opens and closes the friction clutch 8, while the gear wheel 45 of the selector shaft 39 respectively meshes with the gear wheel 13 on the right side of Fig. 1, which gear wheel interacts with the friction clutch 9. Furthermore, a selector drum 40 is attached to each selector shaft 38, 39 in a torsion-proof manner, on the jacket sur-s face of which a coulisse 41 is recessed. The shape of the coulisse 41 is similar to the coulisse 46 of the ring 12 with a long section 49 extending in the circumferential direction, a short section 50 extending in the circumferential direction, and a helical section 51 connecting the two sections, of which the sections 49, 51 are shown in the enlarged view of Fig. 6.

Relating to Fig. 5 again, the selector shafts 38, 39 respectively carry a selector fork 57 and 62. The selector forks respectively comprise a sleeve 52, through which the selector shaft 38 and 39 extend and from which a plate 53 origi-nates which is cut out in a semicircular fashion at its edge and which acts on the selector sleeve 35 and 31 in an interlocking fashion. The sleeve 52 further carries an arm 42 extending along the selector shaft 38 and 39.

Mutually facing recesses are formed at the free ends of the arms 42, which recesses respectively accommodate a joint head 44 at the ends of a coupling arm 43 extendIng between the two selector forks 57, 62. A pin which extends cen-trally through the coupling arm 43 and is movably guided on the housing of the transmission only in the axial direction of the selector shafts 38, 39 forms a pivotal point 54, via which an actuating element 55 acts in an articulated manner on the coupling arm 43. The actuating element 55 comprises two lever arms which origi-nate from the pivotal point 54 and which carry a respective cam 56 engaging in the coulisses 41 of the two selector drums 40, as shown in particular in Fig. 7. The cam 56 is prevented from yielding in the radial direction from the coulisse 41 in that the arms of the actuating element 55 respectively engage in an intermediate space be-tween the selector drum 40 and the adjacently extending arms 42.

The gear wheel 45, the selector shaft 38 or 39, the selector drum 40 with the coulisse 41 therein, and the cam 56 engaging in the coulisse 41 can re-spectively be regarded as a linear actuator of a second type, which respectively converts a rotation of the gear wheel 13 into an axial translatory movement of a selector fork 57 or 62, or the selector sleeve 31 or 35 that is guided thereby.

-10 -In the configuration of Fig. 5, a displacement of the selector fork 62 along the selector shaft 39 is blocked by a cylindrical locking rod 58. which engages in one of several notches 59 on the sleeve 52 of the selector fork 62. The locking rod 58 comprises several notches 60, 61 on its part. As a result of a 90° rotation of the locking rod 58, the notch 60 could be positioned in relation to the notches 59 of the selector fork 62 in such a way that it becomes movable along the selector shaft 38, but at the same time the notch 61 wbuld be transferred from its position facing the notches 59 of the selector fork 57 and permitting a movement of the selector fork 57 to a position blocking the movement of the selector fork 57.

Fig. 8 shows a schematic top view of the control mechanism 37 of Fig. 5 and parts of the manual transmission of Fig. 1 in a neutral position in which the selector sleeves 31, 35 are respectively positioned centrally between the idler gears 29, 30 and 33, 34, and none of the idler gears is coupled to the supporting is shaft 25 and 26, which is merely indicated in Fig. 8 by a dot-dash line. The friction clutches 8, 9 are both open. The cams 56 of the coupling arm 43 engage in the cou-lisses 41 of the selector drums 40 on the boundary between the helical section 51 and the long section 49 extending in the circumferential direction.

In order to engage the first gear, the locking rod 58 is pivoted at first (as shown in Fig. 9), so that its notch 60 faces the notches 59 of the selector fork 62 and releases a displacement of the selector fork 62 along the selector shaft 39. The notch 61 however is twisted away from the notches 59 of the selector fork 57, so that a displacement of the selector fork 57 on the selector shaft 38 is blocked. A servomotor 47 is then activated, which acts via a threaded screw 48 on the gear wheel 45 of the selector shaft 38, so that its selector drum 40 is made to rotate. As a result of this rotation, the cam 56 on this selector drum 40 passes through the helical section 51 of the coulisse, by means of which the end of the actuating ele-ment 55 acting on the shift rod (as shown in Fig. 9) is deflected to the left. Since the selector shaft 39 is not rotated, the second cam 56 of the actuating element 55 stays idle. The actuating element 55 pivots in a clockwise manner, as a result of which the coupling arm 43 on the pivotal point 54 is entrained to the left. Since the selector fork 57 is blocked by the locking rod 58, the joint head 44 of the coupling arm 43 which acts on the selector fork 57 remains immobile, so that the coupling arm 43 pivots in a counterclockwise manner and entrains the selector fork 62 to the -11 -left until the selector sleeve 31 latches onto the idler gear 29 and couples the same to the auxiliary shaft 25. The first gear is thus preselected but not yet engaged.

While the cam 56 has passed through the section 51 of the coulisse on the selector shaft 38, the gear wheel 13 is also twisted on the part of the friction clutch 8, so that the balls 15 are respectively situated on the boundary to one of the outer sections 70 of their ramps 68. The cams 44 of the gear wheel 13 are engaged in the section 49 of the ring 12, so that the selector sleeve 10 remains immobile.

While the servomotor 47 continues to rotate and the cam 56 on the selector shaft 38 passes through the section 50 of its coulisse, the balls 15 continue to proceed further into the outer sections 70 and thereby displace the plates 19 until they strike the plates 20 and close the friction clutch 8, as shown in Fig. 10. The first gear is thus engaged.

In order to shift to the second gear, the selector shaft 39 is twisted by a second servomotor 47 in a direction in which the cam 56 moves forward there to the end of the long section 49 extending in the circumferential direction, as shown in Fig. 11. The selector forks 62, 57 are thus not moved. At the same time, as a result of the rotation of the right gear wheel 13, its cams 14 on the right ring 12 pass through the helical section 51 of the coulisse 46 and thus bring the selector sleeve 11 (not shown in Fig. 11) into engagement with the idler gear 23. The second gear is thus preselected. The selector shaft 38 is twisted back at least to such an extent that the cam 56 is situated between the sections 50 and 51 again on its selector drum 40. The friction clutch 8 is thus opened again. At the same time, the servomo-tor 47 acting on the selector shaft 39 is rotated further. The cams 14 of the right gear wheel 13 pass through the section SOon the right ring 12. The balls 15 pass through outer sections 70 of their ramps 68 thus close the friction clutch 9. Torque is thus transmitted from the drive shaft I via the friction clutch 9 to the hollow shaft 3, via the selector sleeve 11 to the idler gear 23 and from there via a fixed gear 28 to the auxiliary shaft 25.

While the second gear is engaged, the selector sleeve 31 can be separated at any time from the idler gear 29 and the selector sleeve 35 can be brought into engagement instead on the idler gear 33 in order to thus preselect the third gear. For this purpose, the selector shaft 38 is twisted at first so that its cam 56 comes to lie between the sections 51, 49 of its coulisse. As a result, the cam 56 is -12 - displaced in the illustration of Fig. 11 to the right, and the actuating element 55 piv-ots from its position shown in Fig. 11 in a counterclockwise manner and entrains the pivotal point 54 to the right. Since the selector fork 57 is blocked by the locking rod 58, the selector fork 62 is displaced and the selector sleeve 31 returns to the neutral position.

The locking rod 58 is subsequently pivoted, so that the selector fork 62 is blocked and the selector fork 57 is movable. The selector shaft 38 is now twisted in the opposite direction, so that the cam 56 passes through the section 51 there again. The pivotal point 54 is thus entrained to the left. Since in this case, oth- er than in the preselection of the first gear, the selector fork 57 is movable, the cou-pling arm 43 pivots in a clockwise manner, wherein it pulls the selector fork 57 to the left and brings the selector sleeve 35 into engagement on the idler gear 33, as shown in Fig. 12.

In order to disengage the second gear and to engage the third gear, it is sufficient to twist back the selector shaft 39 so that the cam 56 thus reaches the boundary between the sections 50, 51 again, and to position the cam 56 at the end of the section 50 on the selector shaft 38.

In Fig. 13, the cam 56 is situated on the selector shaft 39 at the end of the coulisse section 50, so that the friction clutch 8 is closed and the third gear is engaged. As a result of renewed pivoting of the locking rod 58, the selector fork 57 is blocked in its position retaining the selector sleeve 35 in engagement on the idler gear 33. The selector shaft 39 is twisted in such a way that the cam 56 is situated there between the coulisse sections 51, 50. As a result, the actuating element 55 is pivoted in a clockwise manner beyond that the position of Fig. 12 and the selector fork 52 is displaced to the right beyond the neutral position, so that the selector sleeve 31 is coupled to the gear 30. The fourth gear is preselected by this coupling.

The friction clutch 9 is dosed by further rotation of the selector shaft 39 until the cam has reached the end of the section 50 and the fourth gear is en-gaged. At the same time, the friction clutch 8 is opened again by twisting back the selector shaft 38.

-13 -In order to engage the fifth gear, the friction clutch 9 is opened again and the left gear wheel 13 is simultaneously twisted to such an extent that its cams 14 pass through the sections 51, 49 on the ring 12 and thus bring the selector sleeve 10 into engagement on the idler gear 22 and subsequently close the friction clutch 8.

On the basis of the configuration shown in Fig. 13, it is easy to imag-ine that by renewed pivoting of the locking rod 58 the selector fork 62 can be blocked in the illustrated position and the selector fork 57 can be released. The se-lector fork 57 can be displaced by a rotation of the selector shaft 38 in which the cam 56 passes through the coulisse section 51 there to the right to a position in which the selector sleeve 35 is coupled to the gear 34 and in which the sixth gear can be engaged by opening the friction clutch 8 and closing the friction clutch 9.

Fig. 14 shows a second embodiment of the control mechanism 37, which perspective illustration is analogous to Fig. 5. The two selector shafts 38, 39 and the selector forks 62, 57 which are carried by said selector shafts are the same as in the case of Fig. 5. In addition, a third selector fork 63 and a rod 64 are dis-placeable in the longitudinal direction of the rod 64 for the engagement of a reverse gear in this case, wherein the selector fork 63 -as shown in Fig. 1 -controls a se- lector sleeve 65 on a further auxiliary shaft 66. An idler gear 67, which can be cou-pled by the selector sleeve 65 to the auxiliary shaft 66, meshes with one of the idler gears 29, 30, 33, 34, i.e. the idler gear 30 in this case. The coupling arm 43 is com- posed of two components which are displaceable in a telescopic manner with re-spect to each other, i.e. a rail 71 which connects the pivotal point 54 to the joint head 44 acting on the selector fork 62 and a carriage 72 which is movable on the rail 71 in its longitudinal direction, which covers most of the rail 71 and carries the joint head 44 which is hidden in Fig. 14 beneath the carriage 72 and acts on the selector fork 57 on the one hand, and a joint head 44 that can be coupled to the selector fork 63 on the other hand. A pin 73 which protrudes from the carriage 72 engages in a coulisse 74 which is fixed to the housing of the manual transmission.

Fig. 14 shows the pin 73 in a neutral position, close to the boundary between a sec-tion 75 which is parallel to the selector shafts 38, 39 and a section 76 of the coulisse 74 extending obliquely to the selector shafts.

-14 - The engagement of the first gear proceeds in this embodiment pre- cisely as described for the first embodiment with respect to Figs. 8 to 10. The pivot-ing movement of the coupling arm 43 in a counterclockwise fashion as shown in Fig. 9 leads to the consequence however that the pin 73 moves forward into the oblique section 76 of the coulisse 74 and thus pulls the carriage 73 to the side of the selector shaft 39. On the opposite side, the joint head 44 which is hidden in Fig. 14 disengages from the selector fork 57 and instead the joint head 44 which is visi-ble on the upper side of the carriage 72 engages in a recess on the selector fork 63.

to In order to prepare shifting into the reverse gear, the locking rod 58 -as shown in Fig. 14 -is twisted to an orientation in which its notch 60 blocks the selector fork 52, whereas the notch 61 and a further notch 76 face the notches 59 of the selector forks 57 and 63, so thai they permit their movement. It is clear from Fig. 9 that when the selector shaft 39 is twisted so that the cam 56 reaches the cou-Is lisse section 50 there the actuating element 55 pivots in a clockwise manner about its cam 56 acting on the selector shaft 38. With respect to the illustration of Fig. 9, the pivotal point 54 is displaced to the right and since the selector fork 62 is blocked the coupling arm 43 pivots in a counterclockwise manner and displaces the selector fork 63 in the direction of the locking rod 58, so that the selector sleeve 65 couples the idler gear 67 to the auxiliary shaft 66. When the selector shaft 39 is twisted even further until the cam 56 reaches the end of the section 50, the friction clutch 9 is also closed and the reverse gear is engaged.

This configuration allows the engagement of the reverse gear when the first gear is preselected. Accordingly, direct shifting to the first gear is possible even with preselected reverse gear, so that rapid shifting can be performed be- tween the two gears. Furthermore, two linear actuators of the second type are suffi-cient in order to also control the engagement of the reverse gear in addition to the gears 1, 3, 4, 6 which were already controlled according to the embodiment of Figs. ltol3.

It is understood that the above detailed description and drawings rep- resent specific exemplary embodimenis 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- -15 -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.

Claims

-16 -CLAIMS: 1. A manual transmission, comprising a first and a second selector sleeve (31, 35) which are respectively movable in an axial direction on a shaft (25, 26) of the manual transmission between a neutral position and at least one shifting position in which they couple an idler gear (29, 33) to the shaft (25, 26), a first and a second selector fork (57, 62) which act on the first and second selector sleeve (31, 35) in order to control their axial movement, a first locking element (58) for locking the first selector sleeve (35), a second locking element (58) (or locking the second selector sleeve (31), a coupling arm (43) which is connected to the first and the second selector fork (57, 62) via a first and the second joint (44) and comprises a pivotal IS point (54) between the joints (44) on which an actuating element (55) acts which is movable in the axial direction.
2. A manual transmission according to claim 1, wherein the locking elements (58) are rigidly connected and are movable between a position locking the first selector sleeve (35) and a position locking the second selector sleeve (31).
3. A manual transmission according to claim 1 or 2, wherein the first locking element (58) is pivotable aboul a longitudinal axis between a position locking the first selector sleeve (35) by engagement in a recess (59) of the first se- lector fork (57) and a release position in which a recess (61) of the first lock-ing element (58) faces the recess (59) of the first selector fork (57).
4. A manual transmission according to one of the preceding claims, wherein the actuating element (55) is a two-arm lever which can be pivoted about the pivotal point (54) and of which a first arm is coupled to a first linear actuator (38, 40, 41, 56) driving a movement in the direction of the shaft (25, 26) and a second arm is coupled to a second linear actuator (39, 40, 41, 56) driving a movement in the direction of the shaft.

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5. A manual transmission according to claim 4, wherein a carriage (72) is mov-able along the coupling arm (43) between an idle position and a position coupling a third selector fork (63) to the coupling arm (43).
6. A manual transmission according to claim 5, wherein the carriage (72) inter-acts with a stationary coulisse (74) which comprises a section (75) parallel to the shaft (25, 26) and a section (76) oriented obliquely to the shaft (25, 26).
7. A manual transmission according to one of the claims 4 to 6, which is ar-ranged as a twin-clutch transmission with a first and a second friction clutch (8, 9), wherein the first linear actuator (38, 40, 41, 56) and the first friction clutch (8) jointly comprise a first actuating drive (47), and the second linear actuator (39,40, 41, 56) and the second friction clutch (9) jointly comprise a second actuating drive (47).IS
8. A manual transmission according to one of the claims 4 to 7, wherein the actuating drive (47) is a rotational drive in at least one of the linear actuators (38, 40, 41, 56). and the linear actuator (38, 40, 41, 56) comprises a cou-lisse (41) and a cam (56) interacting wLth the coulisse (41) in an interlocking fashion, which, driven by the actuating drive (47), are pivotable about an axis relative to each other.
9. A manual transmission according to claim 8, wherein the coulisse (41) com- prises at least one section (51) extending helically around the axis and sec-tions (49, 50) which are preferably adjacent to the ends of the helical section (51) and extend in the circumferential direction around the axis.
10. A manual transmission according to claim 8 or 9, wherein the axis extends through a selector shaft (38) on which the selector fork (57) is guided.
11. A manual transmission according to claim 10, wherein the selector shaft (38) is pivotable relative to the selector fork (57) about the axis, and carries a gear (45) on which the actuating drive (47) acts.-is -
12. A manual transmission according to claim 10 or 11, wherein the coulisse (41)18 a groove which is opened radially to the outside and is fixed to the se-lector shaft (38).s
13. A manual transmission according to claim 12, wherein the selector fork (57) carries an arm (42) extending along the selector shaft (38) and an arm of the actuating element (55) engages between the arm (42) and the selector shaft (38). I0