GB2338272A

GB2338272A - Motor vehicle with a device for automated operation of a gearbox

Info

Publication number: GB2338272A
Application number: GB9902231A
Authority: GB
Inventors: Andreas Rogg; Werner Dilger
Original assignee: Robert Bosch GmbH; LuK Getriebe Systeme GmbH
Current assignee: Robert Bosch GmbH; LuK Getriebe Systeme GmbH
Priority date: 1998-02-03
Filing date: 1999-02-02
Publication date: 1999-12-15
Anticipated expiration: 2019-02-02
Also published as: FR2774447A1; ITMI990194A1; KR19990072355A; DE19904022B4; KR100652282B1; DE19904022A1; FR2774447B1; GB2338272B; GB9902231D0; BR9900521A; IT1307662B1

Abstract

A motor vehicle has a drive motor a gearbox and a torque transfer system (eg a clutch). Automated operation of the gearbox is carried out through a control unit and an actor which is controllable by the control unit to shift/select a gear transmission ratio. The control unit is in signal connection with at least one sensor. The actor has a first drive 201 for operating a gearbox element for shifting a gear transmission ratio and a second drive 202 for operating a gearbox element for selecting a gear transmission ratio. The first and second drives 201 operate through gear arrangements elements of the gearbox for shifting the gear transmission ratio and for selecting the gear transmission ratio. Spur wheels 206a are mounted on the output sides of the gear arrangements and mesh with a toothed rack 206b. The rack 206b is rotatable on an axially movable and rotatable shaft 211 and the crests of the teeth of the pinion are engaged in the roots of the teeth of the rack so that the rack is fixed against rotation relative to the pinion.

Description

- 1 1 2338272 Motor vehicle with a device for automated gearbox operation

The invention relates to a motor vehicle with a drive 5 motor, a gearbox and a torque transfer system, with a device for the automated operation of the gearbox with a control unit and at least one actor controllable by the control unit for shifting/selecting a gear transmission ratio, the control unit is in signal connection with at least one sensor and where applicable with other electronics units, the actor has a first drive for operating a gear box element for selecting a gear transmission ratio and a second drive for operating a gear element for shifting a gear transmission ratio.

is Vehicles having automated shift transmissions are known for example with hydraulic actors. The hydraulic operation of the shift elements inside' the gearbox has however proved very complicated and cost-intensive. By way of example extensive elements such as pressure reservoirs, valves and so on are required for the hydraulic actors.

The object of the invention is to provide a motor vehicle having an automated shift transmission which has a reduced number of parts, is more cost-effective and brings an improvement at least in relation to the comfort, such as shift comfort. Furthermore it was an object of the invention to provide a simple system which can be simply fitted and which is small with regard to the structural space required. A device is likewise to be provided which has improved operating security and prevents jamming of individual component parts.

This is achieved with the motor vehicles according to the 1---'".1 1 invention with the above-mentioned devices in that the f irst drive operates through a f irst gearing, such as a worm gearing with spur wheel gear on the output side, an element of the gearing for shifting the gear transmission ratio and the second drive operates through a second gearing, such as a worm gearing, an element of the gearing for selecting the gear transmission ratio wherein a spur wheel is mounted on the output side 'of the worm gear and meshes with a toothed rack wherein the rack is mounted rotatable on an axially movable and rotatable shaft and the tooth heads of the pinion are supported in the tooth base of the teeth of the rack so that the rack becomes secured against rotation relative to the pinion.

This is also achieved according to a further idea according to the invention with motor vehicles according to the invention having the abovementioned devices in that the first drive operates through a first gearing, such as a worm gearing with spur wheel gear on the'output side, an element of the gearbox for shifting the gear transmission ratio and the second drive operates through a second gearing such as a worm gearing, an element of the gearing for selecting the gear transmission ratio whereby a spur wheel is mounted on the output side of the worm gearing and meshes with a toothed rack wherein the rack is mounted rotatable on an axially movable and rotatable shaft and the tooth heads of the rack are supported in the tooth base of the pinion so that the rack becomes secured against rotation relative to the pinion.

It is also expedient if the support of the tooth heads of the rack is provided in the tooth base of the pinion and that of the tooth heads of the pinion is provided in the tooth base of the rack.

1 - 3 It is likewise advantageous if the support is provided over the entire width of the rack.

Furthermore it is expedient if the support is provided on the edge areas of the teeth of the pinion and/or of the rack.

The invention will now be explained in further detail with reference to the drawings in which:

Figure 1 is a diagrammatic illustration of a motor vehicle; Figure 2 shows an operating device according to the invention; Figure 3 shows a lift gear; Figure 4 shows a section of the teeth; Figure 5 is a sectional view through the rack; Figure 6 is a sectional view through a.pinion and rack and Figure 7 is a sectional view through a pinion and-rack.

Figure 1 shows diagrammatically a motor vehicle with a drive motor 1, such as an internal combustion engine, with a torque transfer system 2 and a gearbox 3 in the drive 25 train. Furthermore a differential 4, output shafts 5 and wheels 6 driven by the output shafts are also shown.

Speed sensors (not shown) can be mounted on the wheels to detect the speeds of the wheels. The speed sensors can also belong functionally to other electronics units such as for example anti-lock braking system (ABS). At least one vehicle speed and/or gear speed can be determined from at least one wheel speed by means of a control unit 7.

The drive unit 1 can also be formed as a hybrid drive with for example an electric motor, flywheel with freewheel and 1 an internal combustion engine.

The torque transfer system 2 is formed as a friction clutch wherein the torque transfer system can also be designed for example as a magnetic powder clutch, multiplate clutch or torque converter with converter bridging clutch or another clutch. The friction clutch can also be formed as a self-adjusting clutch which compensates for wear.

The device for the automated operation of a gearbox 3 comprises a control unit 7 and an actor 8 controllable by the control unit 7. The control unit 7 can likewise control an actor 11 for the automatic operation of the torque transfer system. Figure 1 shows a control unit 7 and an actor 8 which is illustrated diagrammatically. The control unit 7 can be formed as an integrated control unit which carries out for example the control or regulation of the torque transfer system and gearbox. Furthermore a motor electronics unit can also be integrated in the control unit. The control of the torque transfer system and gearbox or actors respectively 7, 11 for operating the torque transfer system and gearbox can likewise be carried out by different control units.

it is likewise possible that the control units of the torque transfer system, gearbox and/or engine control are arranged separately and communicate with each other through data and/or signal lines.

Furthermore the control units or electronics units are in signal connection with sensors which send the operating parameters of the actual operating point to the control unit or units.

1 1 It is likewise possible that the control unit receives all required information through data lines or a data bus.

The control unit 7 is fitted with a computer unit in order to receive, process, store, retrieve and forward the incoming signals and system values. Furthermore the control unit generates control values and/or signals f or controlling actors for operation as well as for forwarding to other electronics units.

The torque transfer system 2 is mounted on a f lywheel 2a or connected to same. The flywheel can be a one-piece flywheel or divided flywheel with primary mass and secondary mass wherein a torsion damping device is mounted between the individual flywheel masses, such as for example between the primary mass and secondary mass. Furthermore a starting gear ring 2b can be mounted on the flywheel. The clutch has a clutch disc 2c with friction linings and a pressure plate 2d as well as a clutch cover 2e and plate spring 2f. The self-adjusting clutch has in addition means which allow displacement and wear adjustment wherein a sensor such as a path or force sensor is provided which detects a situation in which an adjustment is required for example as a result of wear and in the event of detection is also carried out automatically.

The torque transfer system is operated by means of a disengagement member 9 by way of example with a disengagement bearing 10. The control unit 7 controls the actor 11 which carries out the activation of the clutch. The activation of the disengagement member can be carried out electro-motorized, elect ro - hydraul ical ly, such as for example operated by pressurised medium, such as hydraulically or by means of another operating mechanism.

1 1 6 The disengagement member 9 with disengagement bearing 10 can be formed as a central disengagement member which is mounted coaxial with the gear input shaft and the clutch is engaged and disengaged by means of biasing for example the plate spring tongues of the clutch. The disengagement member can however also be formed as a mechanical disengagement member which operates, biases or activates a disengagement bearing or a comparable element.

The actor 8 operates more particularly with its at least one output or operating element or with several output or operating elements the gearing 3 for shifting and/or selecting. The control of the shift and/or selection operation depends on the type of transmission.

is of particular consideration are those transmissions having a central shift shaft wherein a shift or selecting process is carried out through axial operation or operation in the circumferential direction of the central shift shaft and vice versa respectively. An actor operates by way of example with one operating element the axial operation of the central shift shaft and with another operating element the operation of the shaft in the circumferential direction. The shift movement can thereby take place in the circumferential direction and the selection operation in the axial direction, or vice versa.

Furthermore transmissions with two shafts are to be considered wherein one shaft is provided for shifting and one shaft for selecting the gear transmission ratio whereby both shafts are operated in the circumferential direction in order" to carry out a shif t process or a selection process.

Transmissions with shift rods are likewise to be - 7 considered wherein the shif t rods are operated axially in order to shift with a shift process a transmission ratio whereby a selection process is implemented through the selection of the operated shift rod.

The shafts or shift rods represent shift elements inside the gearbox or the shafts operate those inside the gearbox in the event of activation. The actor 8 operates directly or indirectly shift elements inside the gearbox for engaging, disengaging or changing gears or transmission ratios, such as a central shift shaft, shafts or shift rods or other shift elements.

The control unit 7 is connected by the signal connection 12 to the actor 8 so that control signals and/or sensor signals or operating state signals can be exchanged, forwarded or interrogated. Furthermore the signal connections 13 and 14 are provided through which the control unit is in signal connection with further sensors or electronics units at 'least at some time. Other electronics units of this kind can be for example the engine electronics, anti-locking braking system electronics or anti-slip regulation electronics. Further sensors can be sensors which generally characterise or detect the operating state of the vehicle, such as for example speed sensors of the engine or wheels, throttle valve position sensors, accelerator pedal position sensors or other sensors. The signal connection 15 produces a connection with a data bus such as for example CAN bus through which system data of the vehicle or other electronics units can be provided since the electronic units are as a rule linked together by computer units.

An automated gearbox can be shifted or a gear change can 35 be undertaken so that this is initiated by the driver of 1 ' 9,4.

the vehicle sending a signal to change up or change down by means of for example a switch, button or other gear selection device 40. Furthermore a signal could also be given to select the next gear to be engaged. A signal can also be provided by means of an electronic shift lever to indicate the gear into which the transmission is to be shifted.

In another transmission program an automated operation of thegearbox can be selected so that the selection of the actual gear is carried out in dependence on the operating parameters and where applicable a shift process is introduced automatically. An automated transmission can however also carry out a gear change automatically by means of for example characteristic values, characteristic lines or characteristic fields and on the basis of sensor signals in the case of certain predetermined points, without the driver having to cause a gear change.

Furthermore a neutral position N can be set by way of example in which there is no drive connection between the gear input and the gear output. Furthermore a parking position P can be selected in which a parking lock is produced. This parking position can also be selected automatically if for example the ignition key 51 is removed from the ignition lock and the operating state of the vehicle permits this. By way of example mention is made of removing the ignition key at high speeds whereby in this situation a parking lock is not to be engaged automatically.

The gear selection unit 40 can thus be set on an area M, such as manual gear selection by the driver, an area D, such as automatic gear selection for driving operation, an area P, such as parking lock and/or an area N such as 9 neutral position. Furthermore a manual shift can be introduced through for example switches or a lever.

The vehicle is preferably fitted with an electronic accelerator pedal 23 or a load lever wherein the accelerator pedal 23 controls a sensor 24 by means of which the engine electronics 20 controls or regulates by way of example the fuel supply, ignition timing, injection timing or throttle valve position through the signal line 21 of the engine 1. The electronic accelerator pedal 23 with sensor 24 is in signal connection with the engine electronics 20 through the signal line 25. The engine electronics 20 is in signal connection with the control unit 7 through the signal line 22. Furthermore a gear control electronics 30 can also be in signal connection with the units 7 and 20. An electromotorized throttle valve control is suitable for this whereby the position of the throttle valve is controlled by means of the engine electronics. With such systems a direct mechanical connection with the accelerator pedal is no longer necessary or expedient.

The vehicle furthermore has an engine starting device 50 which, starting from an attempt to start up the engine by means of for example operating the ignition key 51 in the ignition lock, controls the engine electronics and a starter to start up and/or run the engine.

Figure 2 shows operating devices according to the invention for the automatic activation of a gearbox for operating the shift and selection movement of a central shift shaft of a gearbox whereby one electric motor is provided for each operation such as turning and axially moving the shaft.

- 10 The, device 200 has an electric motor 201 which has on the output side a worm 203 of a worm gear. This worm 203 meshes with a worm gearwheel 205 which is connected by a shaf t to a gearwheel 212 such as a pinion. This pinion meshes with the teeth of a segment gearwheel 213. A shift finger 215 is connected rotationally fixed and axially secured, or is formed in one piece, with the segment gearwheel 213. This shift finger 215 engages in one of the shift fork mouths 216. By turning the finger 215 a 10 shift fork is operated and a gear is engaged. This is controlled by the operation of the electromotor 202. The motor can be operated in reverse and swivel the finger 215 to and fro. Thus one or other gear becomes engaged in the gearbox.

is By moving the shift finger 215 along the axis of the central shift shaft 211 the shift finger is brought into engagement in a shift fork mouth and thus the gear to be engaged or the corresponding shift gate or the 20 corresponding gear group of the shift gear is selected. By turning the shift finger 215 about the axis of the central shift shaft 211 the shift fork is caused to move along the associated shift rod and thus the transmission is shifted.

To produce the rotary and lifting movement of the shift finger 215 which is required to shift the transmission a shift motor 201 and a selection motor 202 are used and controlled by a control unit.

The shift motor transfers its rotary movement through a worm gear with worm and worm gearwheel with an interposed pretensioned elasticity such as energy accumulator and from this to the pinion for shift 212. The worm gearwheel 205, the elasticity and the pinion shift 212 such as 1.11 segment gearwheel are mounted rotatable on a push-in axis 214 which is supported on one side in the housing of the shift motor and on the other side in the actor housing 218. The axis 214 can also be housed and mounted on both 5 sides in the housing of the actor or actuator.

The connection and torque transfer of the worm wheel 205 with the drive side of the elasticity and the connection of the output side of the elasticity with the pinion 212 for shifting are carried out as described above. The rotary movement of the pinion shift 212 is transferred to the segment gearwheel 213 by means of a spur wheel gear whereby the segment gearwheel 213 and the shift finger 215 can be connected together in keyed engagement or can be formed integral. A further shift finger 215a. can be in the the keyed connection with the segment gearwheel 213 or shift finger 215 or can be formed in one piece with segment gearwheel 213 or the shift finger 215.

The segment gearwheel for operating the shift 213 and the shift finger 215 and 215a are fixedly connected to the central shift shaft 212 which is guided for example in at least one slide bearing socket pressed into the actor housing 218.

The selection motor 202 transfers its rotary movement through a worm gear 204 to the pinion 206a for operating the selection movement. The worm wheel 204 and the pinion 206a for selection are mounted rotatable on the push-in axis 207 which is supported on one side in the housing of the selection motor and on the other side in the actor housing 218. The rack 206b for selection is mounted rotatable on the central shift shaft 211 so that the rack 206b is not turned when the central shift shaft 211 is turned about its axis. The teeth of the pinion 206a and - 12 the rack 206b are held parallel to each other by the teeth of the meshing partners being mutually supported. The axial spacing is thus kept constant over the entire width of the tooth engagement.

The rack 206b for selection has faces perpendicular to the rotary axis of the central shift shaft 211. The central shift shaft 211 itself has the corresponding counter faces so that the tangential force of the pinion teeth is transferred through the rack to the central shift shaft 211. The rotation of the pinion 206a for selection causes a displacement of the rack 206b for selection and of the central shift shaft 211 along its axis. The segment gearwheel 213 and the pins 215 and 215a are thereby axially displaced so that they 'can be pushed into different shift fork mouths.

Through the restricted length of the rack 206b for selection and through structural measures such as only partially stamped-out tooth spaces on the edge of the structural part internal stops are provided which restrict the area of movement to that which is necessary or permissible.

The rotary axes of the pinion 206a for selection and of the central shift shaft 211 are perpendicular to each other so that in the area of the lif t and rotary movement of the central shift shaft 211 which is required for shifting the transmission the rotary movement can be executed independently of the position of the pinion 206a for selecting, and vice versa.

The rack 206b for selection is formed in a special embodiment so that it has a slit 230 along the rotary axis of the central shift shaft. The slit 230 changes into a - 13 rotary guide whereby the rotary guide has a slightly larger diameter than the width of the slit. The central shift shaft 211 has an area in which the diameter is severely reduced and corresponds with the rotary guide of the rack 206b for selection. The rotary guide can also be f ormed in areas, e. g. only on the axial edge areas or edges of the rack 206b for selection. The rack for selection is fitted with the slit 230 onto the central shift shaft. Through the slight oversize of the central shift shaft 211 relative to the slit 230 a positive locking connection is produced, such as a snap-fit connection. Since the pinion for selection owing to the above-mentioned internal stops is always in engagement with the rack 206b for selection and the axial space is ensured through the above-mentioned tooth designs, it cannot be pressed down by the central shift shaft.

The teeth of the pinion 212 for shifting and of the segment gearwheel 213 are designed so that the tooth flanks run in the direction of the rotary axes. In the lift and rotary movement area of the central shift shaft required for shifting transmission, a movement of the segment gearwheel and the shift finger fixedly connected thereto can be carried out in the axial direction of the central shift shaft independently of the rotation angle of the segment gearwheel. Also the teeth of the pinion 212 for shifting and the segment gearwheel 213 can be designed so that the tooth heads of the at least one meshing partner are supported in the tooth foot of the other meshing partner before the tooth flanks of the pinion and segment wheel edge are pressed onto each other. This is achieved by a special design of the tooth head. The axial spacing is thus kept constant over the entire width of the toothed engagement and over the entire displacement area.

1 1 With another kinematics of the central shift shaft 211 wherein the shift movement is a sliding movement and the selection movement is a rotary movement, the illustrated design principle can be used by the shift movement 5 becoming the selection movement and vice versa.

The central shift shaft 211 has at its one end area an area with a reduced diameter which is closed by a closure knob.

is This area is housed by a recess 323 of the rack 206b and is mounted rotatable but axially fixed. To this end the rack 206b has side pieces 235 on both sides of the slit which prevent the rack 206b, from escaping.

According to the invention the motor vehicle having a drive motor, gearbox and torque transfer,system such as a clutch, is provided with a device for the automatic operation of the gearbox which (device) has a control unit and at least one actor controllable by the control unit for the automated shifting/selection of a gear transmission ratio of the gearbox. The control unit is thereby in signal connection with at least one sensor and where applicable with other electronics units. The actor has a first drive 201 for operating a gearbox element 216 for shifting a gear transmission ratio and a second drive 202 for operating a gearbox element 211 for selecting a gear transmission ratio whereby the first drive 201 operates through a first gearing such as worm gearing 203, 205 with spur wheel gear 212, 213 on the output side, an element of the gearbox 216 or device 211 for shifting the gear transmission ratio and the second drive 202 operates through a second gearing, such as worm gearing 204, 204a, an element of the gearbox or device 211 for selecting the gear transmission ratio, a spur wheel 206a is mounted on - is the output side of the worm gearing 204, 204a and meshes with a rack 206b whereby the rack 206b is housed rotatably mounted on an axially movable and rotatable shaft 211. it is expedient if the shaft 211 can be raised and lowered axially by means of the second drive 202 through a worm gearing 204, 204a and a gearwheel 206a on the output side and the rack 206b. The shaft 211 is rotatable by means of the first drive 201 through a worm 203 and a worm gearwheel 205 and where applicable through a spur wheel gearing 212, 213 on the output side. To this end the shaft 211 is mounted at least on one side in the housing of the device. The shaft 211 is rotatable by means of the first drive 201 and can be raised and lowered axially by means of the second drive 202 whereby the rack 206b is housed axially fixed but rotatable on the shaft 211 and cannot rotate relative to the gearwheel 206a meshing with the rack 206b even if the shaft is turned. This. is achieved in that the rack and gearwheel are mutually centred by the teeth. The rack 206b has a bore 323 or a slit 230 in the axial direction which holds an area 'of reduced diameter of the shaft 211 rotatable but axially fixed. The shaft 211 has an area of reduced diameter which supports the rack 206b rotatable whereby an end stop is connected to the shaft which axially secures the rack.

The end stop is advantageously formed in one piece with the shaft. In a further embodiment the rack is connected in keyed engagement with the shaft. In a further embodiment the rack is screwed to the shaf t by means of a thread.

The rack has a central axially extending recess 323 such as a bore and an axially extending slit 230 wherein the rack has each side of the slit pliable elastic side pieces 235 which define same.

The rack is formed substantially hollow cylindrical whereby the slit of the rack is mounted in a wall area opposite the teeth.

It is advantageous if the rack 206b and/or the gearwheel 206a meshing with same are made from plastics.

Figure 3 as well as Figures 4 to 7 show a section of a device according to the invention, such as operating device for operating a gearbox, such as for shifting and selecting a gear of a gearbox. The device has a rack lift gear with a rack 301 and a pinion 302 driving this rack 301. By turning the pinion 302 the rack 301 is displaced or lifted axially and executes a lifting movement. The rack 301 is thereby mounted rotatable on a shift shaft 303. A rotation of the shaft 303 causes a shift of gears in the selected shift gate and a lift and lowering of the shaft 303 causes a selection of the shift gate. The rack is thereby housed rotatable between a closure knob 304 and the shaft 303 on a part of the shaft provided with a reduced diameter. The rack lift gearing 300 as selection drive or shift drive of a gear setting device can also be used for shifting if the operating movements of the shaft 303 for shifting and selection are exchanged with regard to their axial displacement and rotation.

The rack 301 is mounted rotatable on the shaft 303 but axially secured with this shaft so that the shaft 303 can execute a rotary movement independent of the rack 301 but the lift movement of the shaft 303 is operated or driven by means of the rack.

According to the invention the rack 301 is not turned during rotation of the shaft 303. This is achieved in that, see Figure 4, the tooth heads 310 of the pinion 302 - 17 are supported in the tooth base 311 of the rack 301 before the flanks 312a, 312b of the teeth contact one another and jam or prevent the movement of the two meshing partners 301, 302. It is thereby achieved that the axial distance between the rack and pinion is kept substantially constant over the entire width of the tooth engagement and thus jamming of the engaged tooth flanks of the teeth is prevented. According to the invention the antirotational lock can also be achieved if the tooth heads of the rack 301 are supported in the tooth base of the pinion 302 and /or a support on the alternate side takes place.

Figure 5 shows the rack 301 in section whereby the rack is formed by a base area 320 which supports the teeth 321.

Two arms 322a, 322b are connected with this base area and form a socket 323 for the area 303a of reduced diameter of the shaft 303.

The flanks 330a, 330b of the rack 301 which protrude further out from the tooth base than the. tooth base protrudes between the flanks serve to supportthe tooth tips 310 of the pinion 302.

Figures 6 and 7 show the arrangement of the pinion 302 and the rack 301 each in cross-section. The pinion 302 is thereby mounted rotatable on the axis or shaft 302a. The pinion 302 meshes by its radially outer teeth 302b with the teeth 301a of the rack 301. The rack 301 is housed rotatable on an area 303a of reduced diameter of the shaft 303 and is centred through the support between the pinion and rack. The patent claims filed with the application are proposed wordings without

prejudice for obtaining wider patent protection. The applicant retains the right to claim 1 18 further features disclosed up until now only in the description and/or drawings.

References used in the sub-claims refer to further designs of the subject of the main claim through the features of each relevant sub-claim; they are not to be regarded as dispensing with obtaining an independent subject protection for the features of the sub-claims referred to.

The subjects of these sub-claims however also form independent inventions which have a design independent of the subjects of the preceding claims.

The invention is also not restricted to the embodiments of the description. Rather numerous amendments and modifications are possible within the scope of the invention, particularly those variations, elements and combinations and/or materials which are inventive for example through combination or modification of individual features or elements or process steps contained in the drawings and described in connection with the general description and embodiments and claims and which through combinable features lead to a new subject or to new process steps or sequence of process steps insofar as these refer to manufacturing, test and work processes.

19 -

Claims

1. Motor vehicle with a drive motor, a gearbox and a torque transfer system such as a clutch, with a device for the automated operation of the gearbox with a control unit and at least one actor controllable by the control unit for the automated shift/selection of a gear transmission ratio of the gearbox, the control unit is in signal connection with at least one sensor, the actor has a first drive for operating a gearbox element for shifting a gear transmission ratio and a second drive for operating a gearbox element for selecting a gear transmission ratio, characterised in that the first drive operates through a first gearing, such as a worm gearing with spur wheel gearing on the output side, an element of the gearbox for shifting the gear transmission ratio and the second drive operates through a second gearing, such as a worm gearing, an element of the gearbox for selecting the gear transmission ratio, whereby a spur wheel is mounted on the output side of the worm gearing and meshes with a toothed rack wherein the rack is rotatable on an axially movable and rotatable shaf t and the crests of the teeth of the pinion are engaged in the roots of the teeth of the rack so that the rack is fixed against rotation relative to the pinion.

2. Motor vehicle with a drive motor, a gearbox and a torque transfer system, such as a clutch with a device for the automated operation of the gearbox with a control unit and at least one actor controllable by the control unit for the automated shifting/selection of a gear transmission ratio of the gearing, the control unit is in signal connection with at least one sensor, the actor has first drive for operating a gearbox element for shifting gear transmission ratio and a second drive for operating 1 a gearbox element for selecting a gear transmission ratio, characterised in that the f irst drive operates through a first gearing, such as a worm gearing with spur wheel gear on the output side, an element of the gearbox for shifting the gear transmission ratio and the second drive operates through a second gearing, such as a worm gearing, an element of the gearing for selecting the gear transmission ratio, wherein a spur wheel is mounted on the output side of the worm gearing and meshes with a toothed rack wherein the rack is mounted rotatable on an axially movable and rotatable shaft and the tooth heads of the rack are supported in the tooth base of the pinion so that the rack becomes secured against rotation relative to the pinion.

3. Motor vehicle according to claim 1 or 2 characterised in that the support of the tooth heads of the rack is provided in the tooth base of the pinion and that of the tooth heads of the pinion is provided in the tooth base of the rack.

4. Motor vehicle according to claim 1, 2 or 3 characterised in that the support is provided over the entire width of the rack.

5. Motor vehicle according to claim 1, 2 or 3 characterised in that the support is provided on the edge areas of the teeth of the pinion and/or of the rack.

6. Motor vehicle with a device for the automated operation of a gearbox and /or a clutch characterised by its special method of operation and design according to the present application documents.

7. Motor vehicle substantially as herein described with reference to the accompanying drawings.