Locking device for a manual transmission

Abstract

A locking device (10) for a manual transmission (4), comprising an actuating element (34); a movable control shaft (32) suitable for controlling a shift fork (30); and a tappet (40), wherein the control shaft (32) comprises at least one recess (42) associated with a switching position, wherein the actuating element (34) is suitable for moving the control shaft (32) along a first axis (A') extending along the longitudinal extent of the control shaft (32), wherein the tappet (40) is movable by means of a spring element (44) along a second axis (A'') running perpendicular to the first axis (A'), wherein the tappet (40) can engage in the at least one recess (42) in the control shaft (32), characterized in that a sleeve (46) is fastened to the actuating element (34), wherein the sleeve (46) surrounds the control shaft (32) and comprises an opening (48) in communication with the at least one recess (42),wherein the opening (48) has a beveled edge (50) such that the diameter of the opening decreases towards the control shaft (32), wherein the tappet (40) comprises a first portion (40') with two inclined surface portions (52) adapted to cooperate with the beveled edge (50) and a second portion (40") adapted to engage the at least one recess (42) in the control shaft (32), wherein the second portion (40") and the at least one recess (42) each comprise two locking surface portions (54', 54").

Description

TECHNICAL FIELDThe present invention relates to a latching device for a manual transmission, wherein a manual transmission comprises such a latching device and a vehicle comprises such a latching device according to the appended claims.BACKGROUNDIt is well known to shift transmissions in manual transmissions or automated manual transmissions (AMT) by moving control shafts or shift shafts connected to shift forks. By moving the shift shaft, a clutch sleeve connected to the shift fork connects / disconnects various transmission gears to / from the main shaft of the transmission. As a result, different gears are engaged / released. In order to achieve a specific shift position of the clutch sleeve, the shift shaft must be moved into a corresponding position. The shift shaft usually comprises two or three grooves, each corresponding to a shift position. A spring-loaded plunger is usually arranged to engage in a groove in the control shaft, whereby a switching position of the control shaft and the clutch sleeve is achieved. The plunger is usually tapered and the groove is shaped accordingly. In this way, when the control shaft is moved in a direction perpendicular to the movement direction of the plunger, the force applied to the control shaft acts on the tapered side of the plunger, thus pushing the plunger away from the groove. The control shaft can thereby be moved. Depending on the spring force and the configuration of the plunger and the groove, a certain force is required in order to push the plunger away from the groove and thus to move the control shaft into a desired switching position. If the correct shift position has been reached, the plunger and the groove should maintain the correct shift position. However, the control shaft and the clutch sleeves may be subjected to several undesirable forces that may cause the control shaft to be displaced from the proper shift position even when no torque is applied to the clutch sleeve. Such forces may occur, for example, due to vibrations, gravity when the gearbox is at a slant, or misalignment of the gears. The spring force by which the plunger remains in the groove must therefore be low enough for the control shaft to be moved to the desired shift position, but large enough to resist the unwanted forces acting on the clutch sleeve and the shift shaft.Various solutions are provided to prevent the shift shaft from being unintentionally displaced and thus to prevent the clutch sleeve from being unintentionally released. Document EP 1 336 774 A1 describes a locking device for a transmission, wherein a shift rod comprises a first, a second and a neutral recess corresponding to a first, a second and a neutral shift position. The neutral recess is disposed between the first and second recesses. The first and second recesses have first and second transition surfaces that incline toward the neutral recess, the second transition surface being steeper than the first transition surface. Document EP 1 152 174 A2 describes a shifting element with detent grooves when the gear is engaged and a detent groove in the idle position with different depths.SUMMARY OF THE INVENTIONEven though solutions in the field are known, the development of a detent device for a manual transmission is still required, which minimizes the force required to achieve a desired shift position and which minimizes the risk of an unintentional release of a clutch sleeve.An object of the present invention is to achieve a detent device that minimizes the force required to achieve a desired shift position.Another object of the present invention is to provide a locking device which minimizes the risk of unintentional disengagement of a coupling sleeve.A further object of the invention is to achieve a latching device which optimizes the switching time.The objects mentioned here are achieved by a latching device, a shift transmission and a vehicle according to the independent claims.According to one aspect of the present invention, a ratchet device for a manual transmission is provided. The latching device comprises an actuating element, a movable control shaft suitable for actuating a shift fork, and a plunger, wherein the control shaft comprises at least one recess assigned to a shift position, wherein the actuating element is suitable for moving the control shaft along a first axis which extends along the longitudinal extent of the control shaft, wherein the plunger is movable by means of a spring element along a second axis which runs perpendicular to the first axis, wherein the plunger can engage in the at least one recess in the control shaft. A sleeve is connected to the actuator, the sleeve surrounding the control shaft and comprising an opening in communication with the at least one recess, the opening having a chamfered edge such that the diameter of the opening decreases towards the control shaft. The plunger comprises a first portion having two inclined surface portions adapted to cooperate with the bevelled edge and a second portion adapted to engage the at least one recess in the control shaft, the second portion and the at least one recess each comprising two locking surface portions. The locking portions preferably extend at an angle to the first axis, the angle being between 70-100 degrees. The locking surface portions preferably extend at an angle between 85-90 degrees to the first axis. The locking surface portions of the plunger and the locking surface portions of the at least one recess preferably have substantially the same inclination.If the control shaft is moved along the first axis due to undesired forces, the inner surfaces of the recess act on the plunger. Thus, the locking surface portions of the at least one recess act on the locking surface portions of the second portion of the plunger. In well known detent devices, both the recess in the control shaft and the plunger are tapered, whereby inclined surfaces of the recess act on inclined surfaces of the plunger. When a force is applied to the control shaft, the control shaft acts with a force on the inclined surface of the plunger, and a reaction force is generated from the plunger. The force acting on the inclined surface of the plunger always has a force component which points away from the recess which counteracts the spring force acting on the plunger. The magnitude of such a force component depends on the inclination of the recess. If the force component directed away from the recess is greater than the spring force and the counterforce component from the plunger, the plunger slides on the inclined surface of the recess and is thereby pressed away from the recess. The smaller the inclination of the plunger surface with respect to the first axis, the greater the force component directed away from the recess. Thus, at a lower slope, a lower force is needed to push the plunger away from the recess. This may be advantageous when a desired force is applied to the control shaft. However, if undesired forces act on the control shaft, there is the risk that the control shaft is unintentionally displaced from its switching position. Since there are locking surface portions extending at an angle between 70-100 degrees to the first axis, the force component of the applied force directed away from the recess is very low or zero. The force component, which is derived, for example, from undesired forces acting on the control shaft, will therefore not be sufficient for the plunger to slide on the surfaces of the recess. The greater the angle of the locking surface portions, the better the resistance to unwanted forces acting on the control shaft. The locking surface portions of the invention thus ensure that the plunger is not inadvertently forced out of the at least one recess. The locking surface portions of the invention ensure that the plunger is not forced out of the at least one recess by moving only the control shaft. In this way, the shift position of the control shaft is maintained and a latching device is achieved which minimizes the risk of unintentional disengagement of the clutch sleeve.The sleeve and the control shaft are preferably movably connected to each other. The sleeve is expediently movable along the first axis by means of the actuating element. The sleeve can only be moved by means of the actuating element and is therefore only slightly influenced by undesired forces acting on the control shaft. The actuator is thus suitable for moving the sleeve and the control shaft. In this way, the sleeve can be moved independently of the control shaft. This also means that the control shaft can easily be moved along the first axis by undesired forces without affecting the sleeve.The plunger is suitably configured such that when the second portion of the plunger engages the at least one recess, the inclined surface portions of the first portion are flush with the chamfered edge of the opening of the sleeve. The inclined surface portions of the first portion and the chamfered edge suitably have respective slopes. In this way, the chamfered edge is engaged with the inclined surface portions when the sleeve is moved along the first axis. The force applied by the actuating element leads to a force component which acts on the inclined surface section, which counteracts the spring force and is directed away from the cutout. With a certain applied force from the actuator, the component of force directed away from the recess is large enough for the inclined surface portion of the plunger to slide on the chamfered edge of the opening in the socket. As long as the sleeve is in a fixed position due to the locking surface portions, the plunger cannot be pushed out of the at least one recess and the control shaft cannot be moved to another shift position. Therefore, in order to intentionally move the control shaft to another shift position, the sleeve must first be moved to cause the plunger to start to lift out of the recess, and thereafter the control shaft may be moved. According to the present invention, the control shaft can only be displaced by first moving the sleeve by means of the operating element. Since, compared to known solutions, the locking surface portions according to the invention result in lower forces counteracting the spring force, the spring force may be lower. With a low spring force, a lower applied actuation force is needed to move the sleeve and control shaft. A latching device is thus achieved which minimizes the force required to achieve a desired shift position. If a lower actuation force is required, the switching process is less time-consuming, since the actuation element can provide the required force more quickly.The first axis preferably runs parallel to the axis of rotation of the main shaft of the transmission which comprises the latching device. When the control shaft is moved along the first axis, the shift fork moves in the same direction. The shift fork is expediently connected to a clutch sleeve which thus moves along the first axis between different shift positions, wherein the clutch connects different transmission gears to the main shaft of the transmission. The second axis may extend along the longitudinal direction of the plunger. The second axis may extend centrally through the plunger along the length of the plunger.The two inclined surface sections of the first section of the plunger are expediently arranged opposite one another and are facing away from one another. The locking surface portions of the second portion of the plunger are conveniently disposed opposite each other. The locking surface portions of the second portion of the plunger are conveniently arranged symmetrically about the second axis. The locking surface portions of the second portion of the plunger are expediently facing away from each other. The locking surface portions of the at least one recess are expediently arranged opposite each other. The locking surface portions of the at least one recess are expediently arranged symmetrically about the second axis. The locking surface portions of the at least one recess are expediently facing away from each other. When the second portion of the plunger engages with the at least one recess, the locking surface portions of the second portion of the plunger respectively face a locking surface portion of the at least one recess. Depending on the direction of movement of the sleeve and the control shaft along the first axis, one of the inclined surface portions of the plunger cooperates with the chamfered edge on a side of the opening in the sleeve, and one of the locking surface portions of the plunger cooperates with one of the locking surface portions of the at least one recess.The control shaft can have a plurality of recesses, preferably two or three. Each recess is assigned a switching position. The recesses in the control shaft are suitably shaped similarly.The plunger is expediently spring-loaded and the spring force of the spring element acts on the plunger in the direction of the control shaft. The spring force thus drives the plunger to engage in the at least one recess in the control shaft. In order to achieve a new shift position, the spring force must be overcome and the resulting force acting on the plunger must be in a direction away from the recess.The plunger may have a substantially circular cross-section. The first portion comprising the two inclined surface portions may thus be shaped in a frustoconical manner, and the second portion comprising the two locking surface portions may thus be shaped in a cylindrical or frustoconical manner. The two inclined surface sections of the first section are thus parts of a lateral surface of the first section. The two surface sections of the second section are thus parts of a lateral surface of the second section. The plunger may alternatively have a rectangular or square cross-section. The first portion comprising the two inclined surface portions may thereby be formed to be tapered, and the second portion comprising the two locking surface portions may thereby be formed to be tapered or cuboidal.The second portion of the plunger and the at least one recess are preferably shaped accordingly. Thus, the cross section of the at least one recess and the longitudinal section of the second section are preferably shaped similarly. The at least one recess in the control shaft may be a bore, a cut-out groove or a recess. If the at least one recess is a bore, the two locking surface sections are parts of a curved circumferential surface. If the at least one recess is a cut-out groove, the recess expediently extends along the width of the control shaft transversely to the longitudinal extent of the control shaft. The two locking surface portions then extend parallel to each other along the width of the control shaft. If the at least one recess is a turned groove, the recess may extend circumferentially around the control shaft. A locking surface portion of the at least one recess cooperates with a locking surface portion of the plunger at a contact surface regardless of the direction in which the control shaft moves along the first axis. If the at least one recess has the shape of a cut-out groove and the plunger has a circular cross section, the contact area between the locking surface portions in the at least one recess and the locking surface portions of the plunger is a so-called linear contact area.The locking surface portions of the plunger preferably extend substantially perpendicular to the first axis. The locking surface portions of the at least one recess preferably extend substantially perpendicular to the first axis. In this way, the force from the control shaft acting on the plunger acts substantially perpendicular to the spring force and thus does not counteract the spring force. The plunger is therefore not pushed out of the recess by the movement of the control shaft.The inclined surface portions on the first portion suitably extend at an angle to the first axis which is between 10-60 degrees, preferably 40-45 degrees. The inclined surface portions preferably extend at an angle to the first axis that is less than the angle of inclination of the locking surface portions of the plunger. The inclined surface sections are expediently configured such that the cross-sectional area of the first section of the plunger decreases in the direction of the second section.The second portion of the plunger preferably includes a tip portion extending from the locking surface portions. According to one aspect of the invention, the second portion of the plunger includes a tapered tip portion. The tip portion may be conical or frusto-conical in shape. The tip portion conveniently extends tapered from the locking surface portions. By using a pointed tip portion, the inclined surface of the tip portion can cooperate with the bevelled edge of the opening in the sleeve when the control shaft and the sleeve are moved along the first axis. The inclined surface of the tip portion is thus influenced by a force from the bevelled edge which counteracts the spring force, so that the resulting force pushes the plunger out of the recess and the sleeve. Alternatively, the second portion of the plunger includes a hemispherical tip portion. The hemispherical tip portion conveniently extends from the locking surface portions. The outer surface of the hemispherical tip portion cooperates with the chamfered edge of the opening in the sleeve when the control shaft and the sleeve are moved along the first axis. The hemispherical tip portion is thus affected by a force from the beveled edge that opposes the spring force so that the resulting force forces the plunger out of the recess and the socket.The first section of the plunger preferably has a larger cross-sectional area than the second section. The second region usually extends from the first region in the direction of the control shaft. The locking surface portions of the second portion are closest to the first portion and the tip portion is further away from the first portion.According to one aspect of the invention, the sleeve and the control shaft are coupled via a circumferential groove in the control shaft and an inner circumferential protrusion of the sleeve, wherein the relative movement between the sleeve and the control shaft is limited by the width of the groove. The width of the groove extends in the direction of the first axis. When the sleeve is moved by the operating member so that the protrusion abuts an edge of the groove, the control shaft is also moved. The sleeve is expediently arranged such that the projection is arranged centrally in the groove when the second portion of the plunger engages in the at least one recess. If the control shaft is to be moved into a new switching position, the sleeve must first be moved independently of the control shaft, whereby the plunger is raised. When the projection abuts an edge of the groove, the control shaft is moved in the same direction as the sleeve and the second portion of the plunger engages the chamfered edge of the opening in the sleeve. The plunger may be pressed completely out of the sleeve and the control shaft can be moved into a new switching position.The transmission in which the latching device is arranged is expediently a manual transmission or an automated manual transmission. According to one aspect of the invention, the actuating element acts pneumatically, hydraulically, electrically, thermally, magnetically or mechanically. According to one aspect of the invention, the actuating element comprises a pneumatic or hydraulic cylinder. The sleeve and the control shaft are thus moved by the force generated by the cylinder. The cylinder is expediently designed such that a predefined force, which is required for moving the control shaft into a switching position, is generated. The cylinder is advantageously electronically controlled by a control unit. The control unit may alternatively determine the applied force required to move the control shaft to a shift position and controls the cylinder so that the cylinder generates the required force. Alternatively, the actuator includes a linkage mechanically connected to a shift lever disposed within the vehicle. The linkage is conveniently controlled directly by the movement of the shift lever. In other words, the operator of the vehicle moves the shift lever and thus controls the linkage that applies a force to the sleeve, so that the sleeve and the control shaft are moved. Alternatively, the actuating element is an electric actuating element which is driven by an electric motor, for example.Other objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details and through the practice of the invention. While the invention will be described below, it is to be understood that it is not limited to the specific details described. Those skilled in the art having access to the teachings herein will recognize other applications, modifications, and incorporations within other ranges that fall within the scope of the invention.BRIEF DESCRIPTION OF THE DRAWINGSFor a better understanding of the present invention and other objects and advantages thereof, the detailed description set forth below should be read in conjunction with the accompanying drawings, in which like reference numerals designate similar items throughout the various diagrams, and wherein: FIG. 1 schematically illustrates a vehicle according to an embodiment of the invention; FIG. 2 schematically illustrates a transmission according to an embodiment of the invention; FIGS. 3 a- bschematically illustrate a latching device according to an embodiment of the invention; FIG. 4 schematically illustrates a latching device according to an embodiment of the invention; FIG. 5 schematically illustrates a latching device according to an embodiment of the invention; and FIG. 6 schematically illustrates a latching device according to an embodiment of the invention.DETAILED DESCRIPTION OF THE DRAWINGSFIG. 1 schematically shows a side view of a vehicle according to an embodiment of the invention The vehicle 1 comprises an internal combustion engine 2 and a transmission 4 with at least one locking device 10. The vehicle 1 can be a heavy vehicle, e.g. a truck or a bus. The vehicle 1 may alternatively be a passenger car.FIG. 2 schematically shows a transmission 4 according to an embodiment of the invention. The transmission 4 can be a manual transmission or an automated manual transmission. The gearbox 4 suitably comprises an input shaft 12 connected to an engine (not shown), a main shaft 14, a countershaft 16 and an output shaft 18. This figure shows a range splitter transmission and therefore includes a splitter transmission 20 connected to the input shaft 12 and a range transmission 22 connected to the output shaft 18. However, the splitter transmission 20 and / or the range transmission 22 may be excluded. The transmission 4 further comprises a plurality of gears 24 which can be connected to the shaft on which they are arranged or can be detached from the shaft. By connecting / disconnecting the transmission gears 24, various gears in the transmission 4 are engaged / disengaged. Such transmission gears 24 may be disposed on the input shaft 12, the main shaft 14, the countershaft 16, and / or the output shaft 18. When the gear 24 is connected to the shaft, the gear and the shaft rotate together. When the gear 24 is detached from the shaft, the gear and the shaft rotate independently of each other. The gears 24 are connected / disconnected by moving the clutch sleeve 26 between different shift positions. The coupling sleeves 26 are suitably connected to a locked gear 28 on the respective shaft, the coupling sleeve 26 connecting a gear 24 to the shaft on which it is arranged via a connection to the locked gear 28. The coupling sleeves 26 are suitably moved along an axis parallel to the extension of the main shaft 14. The movement of the coupling sleeves 26 and thus the connection / disconnection of the coupling sleeves 26 takes place with the aid of latching devices 10. the coupling sleeve 26 is connected to a shift fork 30 and the shift fork 30 is connected to a control shaft 32 of the latching device 10. The control shaft 32 is moved by an operating member 34, thereby moving the shift fork 30 and the clutch sleeve 26. The latch device 10 is further described in FIGS. 3-5. If the transmission 4 is a manual transmission, the actuating element 34 of the latching device 10 can consist of linkages which are mechanically connected to a shift lever 36 arranged within the vehicle 1. If the transmission 4 is an automated manual transmission, the actuating elements 34 can consist of pneumatic or hydraulic cylinders or they can be electronically controlled. The actuators 34 are controlled based on the position of the shift lever 36. Due to the type of the actuating element 34, the connection between the switching lever 36 and the actuating element 34 of the latching device 10 can be mechanical or electrical. This is illustrated by dotted lines in the figure. The gearbox 4 described here is only an illustrative example of a gearbox 4 comprising at least one ratchet device 10 for the gear shift. The transmission 4 could thus be configured differently and can comprise, for example, any desired number of transmission gears 24, clutch sleeves 26 and latching devices 10.FIGS. 3 a, 3 b, 4 and 5 schematically show latching devices 10 according to various embodiments of the invention. The figures show longitudinal sections of the latching device 10. the latching device 10 is configured as described in FIG. 2 and comprises an actuating element 34, a movable control shaft 32 which is suitable for controlling a shift fork 30, and a plunger 40. the control shaft 32 comprises at least one cutout 42 which is associated with a shift position of a clutch sleeve 26 as described in FIG. 2. The control shaft 32 may include a plurality of recesses 42 each corresponding to a shift position. The actuator 34 is adapted to move the control shaft 32 along a first axis A' extending along the longitudinal extent of the control shaft 32. The first axis A' expediently runs parallel to the axis of rotation of the main shaft 14 of the gearbox 4, in which the latching device 10 is arranged. The actuator 34 may be a linkage mechanically connected to the shift lever 36 in the vehicle 1, or the actuator 34 may be a pneumatic or hydraulic cylinder. The actuating element 34 can thus be controlled mechanically or electronically. The plunger 40 is movable by means of a spring element 44 along a second axis A" running perpendicular to the first axis A'. The spring force of the spring element 44 acts on the plunger 40 in the direction of the control shaft 32, so that the plunger 40 can engage in the recess 42 in the control shaft 32. In order to achieve a new shift position, the spring force must be overcome, so that the plunger 40 is pressed out of the recess 42.A sleeve 46 is connected to the actuator 34, the sleeve 46 surrounding the control shaft 32 and comprising an opening 48 in communication with the recess 42. The opening 48 has a beveled edge 50 so that the diameter of the opening decreases toward the control shaft 32. The opening 48 is large enough for the plunger 40 to fit therein. The plunger 40 comprises a first portion 40' having two inclined surface portions 52 adapted to cooperate with the bevelled edge 50, and a second portion 40" adapted to engage the recess 42 in the control shaft 32. The second portion 40" of the plunger 40 includes two locking surface portions 54', and the recess 42 of the control shaft 32 includes two locking surface portions 54". The locking portions 54', 54" extend at an angle α to the first axis A', the angle a being between 70-100 degrees. The locking surface portions 54', 54" preferably extend at an angle α between 85-90 degrees to the first axis A'. The locking surface portions 54' of the plunger 40 and the locking surface portions 54" of the recess 42 preferably have substantially the same inclination. Due to the locking surface portions 54', 54" extending at an angle α between 70-100 degrees to the first axis A', the force component derived from, for example, undesired forces acting on the control shaft 32 is not large enough to push the plunger 40 out of the recess 42. The locking surface portions 54', 54" thus ensure that the plunger 40 is not forced out of the recess 42 by the movement of only the control shaft 32.The inclined surface portions 52 of the first portion 40' of the plunger 40 and the chamfered edge 50 of the opening 48 in the sleeve 46 may have corresponding slopes. The inclined surface portions 52 on the first portion 40' suitably extend at an angle to the first axis A' which is between 10-60 degrees, preferably 40-45 degrees. The inclined surface sections 52 are expediently configured such that the cross-sectional area of the first section 40' of the plunger 40 decreases in the direction of the second section 40".The sleeve 46 and the control shaft 32 are suitably movably connected to each other. The sleeve 46 and control shaft 32 may be coupled by means of a circumferential groove 56 in the control shaft 32 and an internal circumferential protrusion 58 within the sleeve 46, the relative movement between the sleeve 46 and control shaft 32 being limited by the width of the groove 56. The width of the groove 56 extends in the direction of the first axis A'. When the sleeve 46 is moved by the operating member 34 so that the protrusion 58 abuts an edge of the groove 56, the control shaft 32 is also moved. The sleeve 46 is expediently arranged such that the projection 58 is arranged centrally in the groove 56 when the second portion 40" of the plunger 40 engages in the at least one recess 42 and the actuating element 34 is in the idle state. When the control shaft 32 is moved to a new shift position, the actuator 34 first moves the sleeve 46 independently of the control shaft 32, and when the protrusion 58 abuts an edge of the groove 56, the control shaft 32 is moved in the same direction as the sleeve 46.When the second portion 40" of the plunger engages in the recess 42, the inclined surface portions 52 of the first portion 40' are flush with the bevelled edge 50 of the opening 48 in the sleeve 46. the actuator 34 is at rest and the sleeve 46 is fixed. In this manner, the chamfered edge 50 acts on an inclined surface portion 52 when the sleeve 46 is moved along the first axis A'. The force applied by the actuator 34 results in a component of force acting on the inclined surface portion 52 that opposes the spring force and is directed away from the recess 42. With a particular applied force from the actuator 34, the component of force directed away from the recess 42 is large enough for the inclined surface portion 52 of the plunger 40 to slide on the beveled edge 50 of the opening 48 in the sleeve 46. Therefore, in order to intentionally move the control shaft 32 to another shift position, the sleeve 46 must be first moved to cause the plunger 40 to start to lift out of the recess 42 and thereafter the control shaft 32 is moved. As the control shaft 32 is moved, the second portion 40" of the plunger 40 cooperates with the chamfered edge 50 of the opening 48 in the sleeve 46, and the plunger 40 is thereby forced further out of the recess 42 and the sleeve 46. The plunger 40 may be fully pushed out of the sleeve 46 and the control shaft 32 may be moved into a new shift position.The plunger 40 may have a substantially circular cross-section. The first portion 40' comprising the two inclined surface portions 52 may be formed in a truncated cone shape, and the second portion 40" comprising the two locking surface portions 54' may therefore be formed in a cylindrical shape or in a truncated cone shape. The two inclined surface sections 52 of the first section 40' can thus be parts of a lateral surface of the first section 40'. The two surface sections 54' of the second section 40" can thus be parts of a lateral surface of the second section 40". The plunger 40 may alternatively have a rectangular or square cross-section. The first portion 40' comprising the two inclined surface portions 52 may thereby be formed to be tapered, and the part of the second portion 40" comprising the two locking surface portions 54' may therefore be formed to be tapered or cuboidal. The second portion 40" of the plunger 40 and the recess 42 are preferably shaped accordingly. Thus, the cross-section of the recess 42 and the longitudinal section of the second portion 40" are preferably shaped similarly. The recess 42 in the control shaft 32 may be a bore, a cut-out groove or a recess. If the recess 42 is a bore, the two locking surface portions 54" are parts of a curved circumferential surface. If the recess 42 is a cut-out groove, the recess 42 conveniently extends along the width of the control shaft 32 transversely to the longitudinal extent of the control shaft 32. the two locking surface portions 54" then extend parallel to each other along the width of the control shaft 32. If the recess 42 is a turned-in, the recess 42 extends circumferentially around the control shaft 32.The first portion 40' of the plunger 40 preferably has a larger cross-sectional area than the second portion 40". The second portion 40" extends from the first portion 40' toward the control shaft 32. the second portion 40" includes a tip portion 60 that engages the recess 42 in the control shaft 32. The locking surface portions 54 of the second portion 40" are closest to the first portion 40' and the tip portion 60 is further from the first portion 40'. The recess 42 includes a bottom portion 61 corresponding to the shape of the tip portion 60 of the plunger 40.Figures 3a and 3b show a latch device 10 in which the locking surface portions 54' of the plunger 40 extend substantially perpendicular to the first axis A', and the locking surface portions 54" of the recess 42 extend substantially perpendicular to the first axis A'. The angle a is thus substantially 90 degrees. In this manner, the force from the control shaft 32 acting on the plunger 40 acts substantially perpendicular to the spring force, and no force acts against the spring force. The plunger 40 is therefore not forced out of the recess 42. The second portion 40" of the plunger 40 includes a pointed tip portion 60 and the bottom portion 61 of the recess 42 is shaped accordingly. The tip portion 60 may thus be tapered depending on the configuration of the plunger 40. The first portion 40' of the plunger 40 includes inclined surface portions 52 formed as slopes connecting a vertical side of the first portion 40' to a horizontal side of the first portion 40'. Figure 3a shows a situation in which the actuator 34 is at rest, the second portion 40" of the plunger 40 is engaged in the recess 42 and the horizontal side of the first portion 40' abuts the control shaft 32. The plunger 40 thus rests on the control shaft 32. In Fig. 3b, the actuator 34 has moved the sleeve 46 to the right in the figure, which is illustrated by an arrow. The sleeve 46 has thus moved with respect to the control shaft 32 along the first axis A' and the protrusion 58 of the sleeve 46 abuts the right end of the groove 56 in the control shaft 32, and when the sleeve 46 is moved to the right, the force exerted by the left chamfered edge 50 causes the inclined surface portion 52 on the left side of the first portion 40' to slide on the left chamfered edge 50, so that the plunger 40 is partly pushed out of the recess 42. The plunger 40 thus moves along the second axis A" in the direction away from the control shaft 32, as illustrated by an arrow. As the actuator 34 continues to pull the sleeve 46 to the right, the control shaft 32 begins to move in the same direction. As the control shaft 32 moves to the right, the left side of the tapered tip portion 60 of the second portion 40" engages the left chamfered edge 50 of the opening 48 in the socket 46. In this manner, the plunger 40 is fully forced out of the recess 42 and the sleeve 46.FIG. 4 shows a latch device 10 in which the locking surface portions 54' of the plunger 40 extend substantially perpendicular to the first axis A', and wherein the locking surface portions 54" of the recess 42 extend substantially perpendicular to the first axis A'. The latching device 10 is configured as in FIGS. 3a and 3b, except that the first portion 40' of the plunger does not comprise a horizontal side. Instead, the inclined surface portions 52 extend from a vertical side of the first portion 40' to the locking surface portions 54' of the second portion 40". The plunger 40 can thus rest on the bottom of the recess 42 in the control shaft 32 when the actuating element 34 is in a rest state. The control shaft 32 suitably includes inclined surface portions 62 corresponding to the inclined surface portions 52 of the plunger 40. The beveled edge 50 of the opening 48 in the sleeve 46 acts on the sloped surface portions 52 of the plunger 40 as the sleeve 46 is moved along the first axis A'. However, as the control shaft 32 is moved along the first axis A', the pointed tip portion 60 of the plunger 40 initially engages the inclined surface portions 62 of the control shaft 32 and thereafter engages the chamfered edge 50 of the opening 48 in the socket 46.FIG. 5 shows a latching device 10 as described in FIG. 4, with the difference that the locking surface sections 54', 54" of the plunger 40 and the recess 42 extend at an angle a to the first axis A', wherein the angle a is between 85-88 degrees.FIG. 6 shows a latch device 10 in which the locking surface portions 54' of the plunger 40 extend substantially perpendicular to the first axis A' and in which the locking surface portions 54" of the recess 42 extend substantially perpendicular to the first axis A'. The angle a is thus substantially 90 degrees. The inclined surface portions 52 of the plunger 40 extend from a vertical side of the first portion 40' to the locking surface portions 54' of the second portion 40". The control shaft 32 may include inclined surface portions 62 corresponding to the inclined surface portions 52 of the plunger 40. The tip portion of the plunger 40 is hemispherical and the bottom portion 61 of the recess 41 is shaped accordingly. The tip portion 60 of the plunger 40 extends from the locking surface portions 54'. The beveled edge 50 of the opening 48 in the sleeve 46 acts on the sloped surface portions 52 of the plunger 40 as the sleeve 46 is moved along the first axis A'. As the control shaft 32 is moved along the first axis A', the hemispherical tip portion 60 of the plunger 40 cooperates first with the inclined surface portions 62 of the control shaft 32 and then with the beveled edge 50 of the opening 48 in the sleeve 46.The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the invention to the variants described. Many modifications and variations will be apparent to one skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical implementations, and thus to enable those skilled in the art to understand the invention for various embodiments and with the various modifications suitable for the intended purpose.

Claims

Latching device (10) for a shift transmission (4) comprising an actuating element (34); a movable control shaft (32) which is suitable for controlling a shift fork (30); and a plunger (40), wherein the control shaft (32) comprises at least one cutout (42) assigned to a shift position, wherein the actuating element (34) is suitable for moving the control shaft (32) along a first axis (A') which extends along the longitudinal extent of the control shaft (32), wherein the plunger (40) is movable by means of a spring element (44) along a second axis (A") which extends perpendicular to the first axis (A'), wherein the plunger (40) can engage in the at least one cutout (42) in the control shaft (32), characterized in that a sleeve (46) is fastened to the actuating element (34), wherein the sleeve (46) surrounds the control shaft (32) and comprises an opening (48) in communication with the at least one recess (42), the opening (48) having a chamfered edge (50) such that the diameter of the opening decreases towards the control shaft (32), the plunger (40) comprising a first portion (40') having two inclined surface portions (52) adapted to cooperate with the chamfered edge (50) and a second portion (40") adapted to engage the at least one recess (42) in the control shaft (32), the second portion (40") and the at least one recess (42) each comprising two locking surface portions (54', 54").The latching device according to claim 1, characterized in that the locking surface portions (54', 54") of the second portion (40") of the plunger (40) and the at least one recess (42) extend at an angle (α) to the first axis, the angle (a) being between 70-100 degrees.The latching device according to claim 1 or 2, characterized in that the two locking surface portions (54') of the plunger (40) extend substantially perpendicular to the first axis (A').The latching device according to any one of the preceding claims, characterized in that the two locking surface portions (54") of the at least one recess (42) extend substantially perpendicular to the first axis (A').Latching device according to one of the preceding claims, characterized in that the sleeve (46) and the control shaft (32) are movably connected to one another.The latching device of claim 5, characterized in that the sleeve (46) and the control shaft (32) are coupled by means of a circumferential groove (56) in the control shaft (32) and an inner circumferential protrusion (58) within the sleeve (46), wherein the relative movement between the sleeve (46) and the control shaft (32) is limited by the width of the groove (56).Latching device according to one of the preceding claims, characterized in that the second section (40") of the plunger (40) comprises a tip section (60).Latching device according to claim 7, characterised in that the tip section (60) is tapered or hemispherical.Latching device according to one of the preceding claims, characterized in that the actuating element (34) comprises a pneumatic or hydraulic cylinder.A manual transmission (4), characterized bya latching device (10) according to one of claims 1 to 9.Vehicle (1), characterized bya latching device (10) according to one of Claims 1 - 9.

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