WO2005088172A1

WO2005088172A1 - System for implementing a gearshift

Info

Publication number: WO2005088172A1
Application number: PCT/NO2005/000084
Authority: WO
Inventors: Sven BJØRKGÅRD
Original assignee: Kongsberg Automotive Asa
Priority date: 2004-03-12
Filing date: 2005-03-07
Publication date: 2005-09-22
Also published as: SE0400621L; SE0400621D0

Abstract

A system for implementing a gearshift comprises a gearbox provided with a shift shaft equipped with two or more shift forks and a gear level. The gear level is movable in a first direction for selecting a shift fork or one or more sensor devices, for direct selection of a shift fork are included in the system. The gear lever is movable in a second direction for shifting between the different gear ratios. Each shift fork is equipped with a locking device and can be guided alternately between a first position where the shift fork is locked to the shift shaft and a second position where the shift fork is not locked to the shift shaft. One shift fork at a time is locked to the shift shaft while the rest are not locked. The invention also comprises a system that is controlled by a data processing unit.

Description

System for implementing a gearshift

The present invention relates to a system for shifting gears according to the introduction, to the independent patent claims in the set of claims.

The invention will preferably be employed in vehicles of different types, but may also be applied within other technical fields where it is desirable to undertake a shift between different gear ratios. Other vehicles such as ships, small boats etc. may be briefly mentioned here.

In conventional gearshift systems currently on offer, gearboxes with several shift shafts are often employed. According to established technology each shift shaft is provided with a shift fork, each of which is connected to a shift sleeve in order to perform a gearshift. The shift fork together with its shift sleeve may be moved between different positions for shifting between different gear ratios and possibly the neutral position. When a gear is selected by means of the gear lever or by automatic gear selection, the shift shaft connected with the desired gear ratio is engaged. The shift shaft is then moved in its longitudinal direction for shifting to a new gear ratio. ^{' '} -

Since several shift shafts are presumably included in the gearbox, the gearbox will be relatively large and require a great deal of space, its construction will be relatively complex and the gearbox will be expensive. This applies particularly in cases where gearbox solutions have many gears, for example where the gearbox has six different gear ratios in addition to reverse gear. In this case the gearbox may contain as many as four different shift shafts; a shift fork for each gear pair together with a shift fork for reverse gear. Such a gearbox requires a lot of space and in addition has an extensive construction with many different parts that have to fit together and be moved relative to one another.

A starting point for making the gearbox simpler and smaller is to reduce the number of components by using only one shift shaft in the gearbox. The principle of using a shift shaft is per se previously known.

,We shall now refer to US 3929029 in which a gearbox is described where the shift forks are attached to a shift shaft. The shift shaft can be moved by a rotating motion or by movement in the longitudinal direction. In the case of rotating motion of the shift shaft, one of the shift sleeves with associated shift fork is selected, while the remaining shift forks are locked by locking devices. On subsequent movement of the shift shaft in the longitudinal direction, the selected shift fork is moved from one position to another in the axial direction in order to perform a gearshift, while the remaining shift forks are kept locked by the locking devices and prevented from moving axially. Since the relevant shift fork has to be selected by means of a selector mechanism while the movement of the remaining shift forks has to be prevented, this solution requires a large number of components, all of which have to cooperate in a relatively complex sequence. We further refer to US 6389919, where a gearbox is given a compact design by a common shaft being employed for all the shift forks. The shift forks are provided 5 with a mounting portion for fixing the shift forks to the shaft. The mounting portions are provided with a through-going opening, the inside of which is provided with a projection which is received in a groove extending in the shaft's longitudinal direction, when the shaft is passed through the shift forks' mounting portion. The gearbox is further equipped with an actuator provided with a selector mechanism

10 , designed to engage with a projecting portion belonging to the shift fork that requires to be selected. After selection of a shift fork, the shift fork is moved into engagement with the shift sleeve in the axial direction on the shaft for selection of gear ratio. In this solution, therefore, the shift forks' common shaft acts only as a guide for the shift forks' movement, the actual shift movement being initiated by

15 the actuator. From US 573147 and EP 131720 a gearshift device is known where several shift forks are mounted on the same shift shaft. According to both US 573147 and EP 131720 a shift fork is selected by means of rotating motion of the shift shaft, and the shift fork concerned is secured to the shift shaft. When the shift shaft is moved,

20 only the selected shift fork is moved while the rest are moved slidingly on the shift shaft. US 573147 and EP 131720 are focused on the methodology of attaching shift forks one by one to the shift shaft. Neither in US 573147 nor in EP 131720 is any solution indicated as to how gear selection performed by a gear lever or an automatic gear selection device (data processing device) should be communicated

25 and translated into selection of the shift fork. This, however, is a problem that the present invention aims to solve, as will now be explained. On the basis of the disadvantages involved in current solutions, there are great potential benefits, both with regard to operation and to costs, in providing a gearbox solution, which is compact and has a simple construction with efficient functioning.

30. The object of the invention is therefore to provide a gearshift system that includes a gearbox, which has a simpler construction compared to conventional gearboxes. By reducing the number of components in the gearbox and achieving a more efficient assembly of the gearbox parts, a more compact gearbox is provided, which will also be less expensive than the gearboxes currently on offer. A further object of the

35 invention is to provide a simple solution for selecting a shift fork when the gearbox is equipped with only one shift shaft and a gear lever or more automatic device is employed for gear selection. The objects of the invention are achieved according to the invention as indicated in the characteristics of the independent patent claims, with further embodiments of the invention being indicated in the dependent patent claims.

In the system as indicated in the independent patent claim 1 , it is stated that a gear lever is connected to the gearbox. It will be possible, however, to use the invention in a context where gear selection is performed automatically or semi-automatically. It is also possible to employ other operating devices than a gear lever for gearshift, . for example a joystick, a sensor device such as a switch, for example a push-button or the like. There are many options here when choosing an operating device, and the essential features are that the operating device should be user-friendly and the user's settings transferable, and possibly translatable, for controlling the gearbox.

All of these possible alternatives are based on the same principle that a shift fork is selected by a gear lever or other method of selection, for example automatic gear selection, or a switch that is activated directly by the driver, whereupon the shift fork is locked to the shift shaft, after which a shift to a new gear ratio is performed by movement of the shift shaft.

The system according to the invention as indicated in the independent patent claim 1 can be used for systems where the gear lever can be moved in different gear path patterns. Mention may be made here of a sequential gear, which for example is used on motorcycles, where the gear lever is moved in a rectilinear motion. Furthermore, the gear path pattern is in the form of an H, where the gear's neutral position is located on the H's horizontal leg, and gearshift is initiated by positioning the gear lever in one of the two ends of the H. A gear path pattern in the form of a double H may also be possible. For both H and double H there may an extra tail for selection of reverse gear or for selection of reverse gear and a fifth gear, as is normally the case for gear levers used in passenger cars. A gear lever that follows a simple H- shaped gear path pattern, but which in addition has the functions "split" and "range" is widely used in lorries.

The system for implementing a gearshift according to the independent patent claim 1 may comprise a gearbox and a gear lever that are directly or indirectly interconnected, where the gear lever's movements are communicated to the gearbox. In the independent patent claim it is also stated that the gearbox may be operated by activating a sensor device such as a switch, with one or more switches mounted^' in the vehicle's cabin so as to be easily accessible for the driver. The gearbox is provided with a shift shaft equipped with two or more shift forks, each of which is engaged with a shift sleeve, where the shift fork moves the shift sleeve between different positions for shifting between different gear ratios and possible neutral position. The gear lever operates the gearbox, the gear lever being movable forwards and backwards between different positions in a gear path pattern comprising a first direction of travel where the relevant shift fork is selected and locked to the shift shaft, and a second direction of travel for shifting between the different gear ratios, where movement of the gear lever in the second direction of travel involves movement of the shift fork and subsequent shifting to a new gear ratio.

Instead of movement of the gear lever in the first direction of travel, in a second embodiment the invention is equipped with a gear lever for implementing a sequential gearing, which is only movable in the second direction. In this solution one or more driver-operated switches such as push-buttons or the like are employed for selecting a shift fork. These switches may, for example, be mounted on the gear lever. An advantage of this embodiment of the invention is that the mechanics in the gear lever are relatively simple.

The system according to the independent patent claim 1 is characterised in that each shift fork is separately attached to the shift shaft and equipped with a controllable locking device. Movement of the gear lever between the different positions in the first direction or activation of the sensor devices/switches initiates locking of one of the shift forks and unlocking of the remaining shift fork(s). Each shift fork may thereby be guided alternately between a first position where the shift fork is locked to the shift shaft, thereby following the shift shaft's movement, and a second position where the shift fork is not locked to the shift shaft and the shift shaft can be moved relative to the shift fork(s). One shift fork at a time is thereby locked to the shift shaft while the rest are not locked and when the shift shaft is moved, the shift fork that is locked to the shift shaft causes a shift to a new gear ratio. When a gear lever is employed for operating the gearbox, the gear lever according to conventional technology may be directly coupled to the shift shaft, preferably by the gear lever's lower end being coupled to the shift shaft. Alternatively, the gear lever may be connected to the shift shaft by a transmission, with the result that the gear lever's movement or change of position is transmitted as a signal or as a power transmission, preferably by means of a pneumatic or hydraulic fluid transmission, cables or as a purely mechanical transmission.

In an embodiment of the system where a gear lever is employed, movement of the gear lever between the different positions in the first direction initiates locking of one of the shift forks and unlocking of the remaining shift fork(s) by means of the controllable locking devices. Alternatively, locking of the relevant shift fork may be performed by operating a switch (for example a push-button) for selecting the shift fork. In this case the switches can be placed on the gear lever. Thus the relevant shift fork is selected by means of movement of the gear lever in the first direction or by operating the switches. The movement of the gear lever forwards or backwards in the first direction is therefore a possibility for selecting which shift fork is to be locked to the shift shaft. When the invention is used in a vehicle, this first direction will preferably be a direction that is oriented across the vehicle's longitudinal direction, i.e. a transverse direction extending from one side of the vehicle to the other. If the gear path pattern is H-formed, this means that movement in the first direction is movement along the H's horizontal leg. The movement of the gear lever in the first direction or information on which of the „ driver-operated sensor devices/switches are activated can be transmitted to the locking devices on the different shift forks in various ways. One or more sensors may be employed, located close to or distant from the gear lever for registering the gear lever's movement.

The sensor device or the sensor may be a pressure sensor, a mechanical switch, an optical switch such as a photocell, or another suitable sensor. The sensor information may be transmitted to the shift fork's locking device in various ways and will be transmitted directly or converted depending on the design of the locking devices' signal or data receivers. The transmission may be conducted in various ways. One possibility is transmission- via cables as an electrical or optical signal. Alternatively, the transmission may be conducted by using a system of pipes and cylinders with a pneumatic or hydraulic working medium, where the system is controlled by mechanically or electrically operated valves, which receive signals from the sensors. The gear lever may also operate the valves directly without the use of sensors.

A more direct transmission may also be envisaged where sensors are not necessarily employed, but where movement of the gear lever is transmitted directly by means of a mechanical transmission, transmission by means of cables, etc. Yet another possibility is the use of a computer for communication between the gear lever, or other gear-operating unit if this is used, and the shift forks' locking device. If the gear solution is automatic and no gear-operating unit is employed, a control unit such as a computer may be used for controlling which locking devices are to be locked or unlocked.

In a preferred embodiment of the invention, movement of the gear lever in the second direction, which in the case of the invention is used in a vehicle, will mean movement of the gear lever in a direction coincident with the vehicle's longitudinal direction extending from the vehicle's front end to the vehicle's rear end. If the gear path pattern is H-shaped, this means that movement in the second direction is movement along the H's vertical leg. Movement in this second direction entails movement of the shift fork in its longitudinal direction and subsequent shifting of the gear ratio. As mentioned earlier, the invention also comprises a system for implementing a gearshift for use together with other selection or operating devices than a gear lever, such as an automatic or semi-automatic solution, or possibly the use of an actuator for selection of a shift fork and shifting thereof. Such a system is described in the independent patent claim 5. This system also comprises a conventional per se gearbox, which is provided with a shift shaft equipped with two or more shift forks, each of which is engaged with a shift sleeve. The shift fork moves the shift sleeve between different positions for shifting between different gear ratios, this being carried out by the shift shaft being moved in the shift shaft's longitudinal direction. The system further comprises a data processing unit, which selects the appropriate gear ratio. The data processing unit can determine or select the appropriate gear ratio on the basis of various types of incoming parameters. The selected gear ratio can be communicated directly to the gearbox and/or to a control unit which in turn controls the gearbox. Each shift fork is separately attached to the shift shaft and equipped with a controllable locking device. In the event of an ingoing signal to the gearbox from the control unit and/or the data processing unit, each shift fork can be guided alternately between a first position where the shift fork is locked to the shift shaft and thereby follows the shift shaft's movement, and a second position where the shift fork is not locked to the shift shaft and the shift shaft can be moved relative to the shift fork(s). One shift fork at a time is thereby locked to the shift shaft while the rest are not locked and on movement of the shift shaft, the shift fork that is locked to the shift shaft causes a shift to a new gear ratio.

A preferred embodiment of the shift forks' attachment and locking to the shift shaft, which is suitable for-both the system where a gearshift is performed manually by means of a gear lever and for the system where a gearshift is automatic, will now be described. A person skilled in the art will understand that the attachment and locking of the shift forks to the shift shaft may also be performed in other ways within the scope of the invention. Each shift fork is provided with a mounting portion with a through-going bore, the shift shaft being passed through the bore(s). In an embodiment of the invention the shift shaft is provided with an opening and the mounting portion is provided with an opening. The shift fork's locking device comprises a locking pin that causes the shift fork to be locked to the shift shaft by a portion of the locking pin being received in the shift shaft's opening and a portion in the mounting portion's opening. When the shift fork is not locked, the locking pin is located in the shift shaft's opening or in the mounting portion's opening.

In yet another embodiment of the invention the shift shaft's opening may be through-going in the shift shaft's diametrical direction, preferably with a length that at least corresponds to the shift shaft's diameter. The shift fork's mounting portion is provided with a locking groove for receiving a portion of the locking pin when the shift fork has to be locked to the shift shaft. In this embodiment the locking pin may be positioned in such a fashion that the locking pin protrudes through the shift shaft's through-going opening and is received in the locking groove or both in the locking groove and the mounting portion's opening, when the shift fork is locked to the shift shaft.

The mounting portion's opening may be in the form of a through-going opening through the mounting portion's material thickness, whereby it can be positioned over the shift shaft's through-going opening and aligned therewith. In this case the locking pin may be of such a length that in the shift fork's locked position, the locking pin extends through the mounting portion's through-going opening and the shift shaft's through-going opening, possibly to be received in the mounting portion's locking groove. In another embodiment of the invention the locking device may comprise a locking- initiating device that extends through the mounting portion's through-going opening to abut against the locking pin, where the locking pin may be adapted to be received in the mounting portion's locking groove. When using a locking-initiating device, the locking pin will have a shorter length, preferably corresponding to the shift shaft's diameter. In a preferred embodiment of this solution the locking pin is received in the shift shaft's through-going opening when the shift fork is not locked. The locking-initiating device moves the locking pin in the through-going opening so that a portion of the locking pin is received in the locking groove.

For the above-mentioned solutions a spring- loaded return device mounted in the locking groove may be employed, which causes the locking pin to be returned when the shift fork is unlocked.

As mentioned earlier, the individual shift fork's locking device is provided in a controllable form that enables it to alternate between a state where the shift fork is locked and a state where the shift fork is unlocked. The control of the individual shift fork may be conducted in various ways, but one way of doing this is to use an activating element provided on the shift fork's mounting portion.

In an embodiment of the activating element, activation of the element causes locking of the shift fork to the shift shaft, while deactivation of the element causes unlocking of the shift fork. When this method of controlling the locking device is used together with the aforementioned embodiment of the locking device where the mounting portion is provided with a locking groove, the invention works in the following manner: on activation the locking-initiating device or the locking pin is moved through the mounting portion's through-going opening and the locking pin is moved in the shift shaft's through-going opening, with the result that a portion of the locking pin is received in the locking groove and the shift fork is locked. During unlocking the parts are withdrawn. This locking principle can be implemented in many ways, but in an embodiment the locking-initiating device or the locking pin is prestressed by means of a spring. Deactivation of the activating element causes the locking pin to be withdrawn from the locking groove by means of the spring's pre- tensioning force.

In a second embodiment of the locking device, activation of the activating element causes unlocking of the shift fork, while deactivation of the element causes locking of the shift fork. On activation of the activating element, the locking-initiating device or the locking pin is similarly withdrawn through the mounting portion's through-going opening, and the locking pin is moved in the shift shaft so that a portion of the locking pin is removed from the locking groove and the shift fork is unlocked. On locking, the parts are moved so that the locking pin is inserted in the locking grove as has also been described earlier. This locking principle can be implemented in many ways, but in an embodiment the locking-initiating device or the locking pin is held in a locked position by a spring. Activation of the activating element leads to the establishment of a force with a direction that overcomes the spring's force, thereby causing the locking pin to be withdrawn from the locking groove. In a preferred embodiment the activating element is composed of a solenoid. The solenoid's movable core is magnetic and constitutes the locking pin or the locking- initiating device. The coil also encircles the core. When current is supplied to the solenoid, the solenoid is activated, thereby causing the shift fork to be locked to the shift shaft, or unlocked depending on which locking principle is chosen. The solenoid may, for example, be single-acting with spring return or double-acting without a spring.

The activating element may also be in the form of a cylinder with a piston, which for example is pneumatically or hydraulically controlled, where a portion of the piston constitutes the locking pin or the locking-initiating device. The shift forks on one and the same shift shaft may be equipped with the same or different types of locking mechanism. The above-mentioned examples of different locking principles for the locking mechanism and the different activating elements may therefore be employed according to the wishes of the skilled person for the different shift forks. With a combination of similar or dissimilar types of solenoids, the combination is arranged in such a manner that at least one shift fork is locked to the shift shaft when the solenoid is not powered. By this means a safety function is provided where one of the shift forks is locked to the shift shaft even though the power supply to the solenoids should be interrupted. When it is double-acting, moreover, the solenoid can be arranged in such a manner that the current is broken when the locking pin/the core reaches its end position. This is to prevent the solenoid from being powered when no gearing is taking place.

The activating element can be provided as a separate unit on the shift fork's mounting portion or the activating element can be provided as an integrated part of the mounting portion.

It may be briefly mentioned here that the activating element may alternatively be comprised of an actuator, which may be controlled by a control signal generated from a computer as a result of the gear lever's movement in the first direction or in another way.

An embodiment of the invention will now be described with reference to the attached figures, in which:

Fig. 1 illustrates an embodiment of the system according to the invention. Fig. 2 illustrates a second embodiment of the system according to the invention. Figs. 3-5 illustrate alternative embodiments of the shift forks' locking mechanisms and activating elements.

Fig. 6 illustrates an embodiment of the system where gears are selected automatically. Fig. 7 illustrates an alternative embodiment of the gear lever. In figure 1 a system is illustrated where a gear lever 1 is shown in direct engagement with a shift shaft 2. The shift shaft 2 is here equipped with two shift forks 3, 4, each of which is engaged with a shift sleeve (not shown) for shifting between different gear ratios. As will be appreciated by a skilled person, the number of shift forks may vary. Each shift fork has a mounting portion 3 a, 4a with a through-going bore 3b, 4b, through which the shift shaft 2 is passed and each shift fork can be locked separately to the shift shaft. The gear lever 1 can be moved in a first direction for selection of a shift fork, the first direction of travel being illustrated by arrow 5, and a second direction for shifting gear ratio, the second direction of travel being illustrated by arrow 6. In the illustrated embodiment these are oriented 90° to each other.

Movement of the gear lever 1 forwards and backwards in the first direction is registered by the sensors 7 and 8 respectively. When the gear lever 1 is moved in the direction of the sensor 7, this is registered by the sensor 7, which transmits a signal to the shift fork 4, which is locked to the shift shaft 2. Only one shift fork at a time can be locked to the shaft, and the movement of the gear lever 1 in the direction of the sensor 7 causes the shift fork 3 to be unlocked. In the illustrated example the unlocking of the shift fork 3 may be performed either by no signal being transmitted to the shift fork 3 or by an unlocking signal being transmitted to the shift fork 3 due to information from sensor 8. The same applies in the case of movement of the gear lever 1 in the direction of sensor 8, which causes the shift fork 3 to be locked to the shift shaft 2, while the shift fork 4 is then unlocked. It should be mentioned here that when more than two shift forks are employed, the sensors are arranged at the gear lever in such a manner that the associated sensors are activated within the area of the first direction 5 corresponding to the selection of the respective shift fork.

When shift fork 3 or 4 is selected on movement in the first direction 5, the gear ratio can be selected by the gear lever 1 being moved in the second direction 6. On movement of the gear lever 1 in the second direction 6, the shift shaft 2 is moved in its longitudinal direction. By means of this movement the locked shift fork is moved, while the unlocked shift fork is at rest, and a shift of gear ratio is implemented.

Figure 2 illustrates the same set-up as in figure 1 , but here the connection between the shift shaft 2 and the gear lever 1 is established by a cable 9. The other components are the same as in figure 1 and are indicated by the same reference numerals.

Figure 3 is a sectional view through a shift fork 4 illustrating an example of a method of controlling the locking of the shift fork 4 to the shift shaft 2. The shift shaft 2 is illustrated here with a through-going opening 2a. The mounting portion 4a is provided with a locking groove 10 and a through-going opening 11. On the mounting portion 4a there is provided an activating element 12 in the form of a solenoid where the solenoid's core acts as a locking pin 13a. The solenoid's coil is indicated by 14. When the shift fork 4 receives a signal that it has to be locked to the shift shaft 2, current is supplied to the solenoid and a magnetic field is established at the coil 14. When the voltage field is established, the locking pin 13a is moved downwards to be received in the locking groove 10. When the shift fork has to be unlocked, by means of signal input to the shift fork 4 or by lack of signal input to the shift fork 4, a voltage field can be established with a direction that guides the locking pin out of engagement with the locking groove 10.

In figure 4 a second embodiment is illustrated of the shift fork's 4 locking device and of the solenoid. Here the locking pin is designed as illustrated by 13b, and the component 13a which in the example in figure 3 acted as a locking pin acts as a locking- initiating device 15 in the embodiment in figure 4. A spring 18 is illustrated arranged round the locking-initiating device 15. In the locking groove 10 there is placed a return device 16, which is prestressed by a spring 17. The springs 17 and 18 hold the locking-initiating device 15 and the locking pin 13b in a position where the shift fork is not locked to the shift shaft 2. In the event of signal input to the shift fork 4, a magnetic field is established in coil 14 with a force and direction that overcome the force from the spring 17 and 18. The locking-initiating device 15 is thereby pushed downwards towards the locking pin 13b, which is moved downwards and received in the locking groove 10. The shift fork 4 is thereby locked to the shift shaft 2. The shift fork 4 is unlocked from the shift shaft 2 by removal of the magnetic field, for example by cutting off the signal input and thereby the power supply to the solenoid. The locking-initiating device 15 and the locking pin 13b are then returned to the position illustrated in figure 4.

In figure 5 an arrangement is illustrated corresponding to that illustrated in figure 4, but in this case the shift fork 4 is shown locked to the shift shaft 2. In figure 5 it can be seen that the spring 18 has been moved so that it holds the locking-initiating device 15 and the locking pin 13b in a position where the locking pin 13b is received in the locking groove 10. With this arrangement the object is achieved that in its initial position the shift fork 4 is locked to the shift shaft 2. In order to unlock the shift fork 4 it is necessary to supply current to the coil 14 in order thereby to establish a magnetic field, which has a force and direction that overcome the spring force of the spring 18. The current supplied to the solenoid can be controlled by sending a signal to the shift fork 4.

Figure 6 illustrates an example of a set-up of the system where a gearshift takes place automatically. A data processing unit 20 selects the appropriate gear ratio. Based on the selected gear ratio the data processing unit 20 transmits a signal concerning selection of one of the shift forks 3 or 4. The shift fork concerned is locked to the shift shaft 2. A gearshift actuator 21, which is connected to the shift shaft and communicates with the data processing unit 20 then ensures that the shift shaft is moved in the longitudinal direction for selection of a new gear ratio. Figure 7 illustrates an alternative embodiment of a gear lever 30 for selecting a shift fork according to the invention. The gear lever 30 is only movable in the second direction and as an alternative to movement of the gear lever 30 in the first direction of travel for gear selection, one or more driver-operated sensor devices, illustrated here as push-buttons 31, are employed for selecting a shift fork as illustrated in the figure.

Claims

CLAIMS 1. A system for implementing a gearshift preferably in a vehicle comprising - a gearbox provided with a shift shaft equipped with two or more shift forks, each of which is engaged with a shift sleeve, the shift fork moving the shift sleeve between different positions for shifting between different gear ratios, - a gear lever for operating the gearbox, where the gear lever is movable in a first direction of travel for selecting a shift fork or one or more sensor device(s) preferably switches for direct selection of a shift fork are included in the system, preferably by the switches being placed on the gear lever, the shift fork being selected by movement of the gear lever in the first direction or by operating one of the switches, and furthermore that the gear lever is movable in a second direction of travel for shifting between the different gear ratios, where movement of the gear lever in the second direction of travel results in movement of the shift shaft and subsequent shifting to a new gear ratio, characterised in that each shift fork is separately attached to the shift shaft and equipped with a locking device and can be guided alternately between a first position where the shift fork is locked to the shift shaft, thereby following the shift shaft's movement, and a second position where the shift fork is not locked to the shift shaft and the shift shaft can be moved relative to the shift fork, one shift fork at a time being locked to the shift shaft while the rest are not locked and on movement of the shift shaft, the shift fork which is locked to the shift shaft causes shifting to a new gear ratio, where movement of the gear lever between the different positions in the first direction or operation of the switch initiates locking of one of the shift forks and unlocking of the remaining shift fork(s).

2. A system for implementing a gearshift according to claim 1, characterised in that the movement of the gear lever in the first direction is transmitted to the locking devices on the various shift forks, either by means of a mechanical connection, through a cable or a fluid transmission preferably in the form of a system of pipes, cylinders and valves which are electrically or mechanically operated or a combination thereof.

3. A system for implementing a gearshift according to claim 1, characterised in that the movement of the gear lever in the first direction is registered by one or more sensors placed close to or distant from the gear lever.

4. A system for implementing a gearshift according to claim 1 or 3, characterised in that the sensor information from the sensor devices or the sensors placed close to or distant from the gear lever is transmitted directly or converted before signal transmission to the shift forks which may be equipped with a signal receiver, where the sensor/sensor device is a pressure sensor, a mechanical switch, an optical switch such as a photocell, and that the sensor information is transmitted to the shift fork's locking device as an electrical or an optical signal.

5. A system for implementing a gear shift preferably in a vehicle comprising - a gearbox provided with a shift shaft equipped with two or more shift forks, each of which is engaged with a shift sleeve, the shift fork moving the shift sleeve between different positions for shifting between different gear ratios, on movement of the shift shaft in the shift shaft's longitudinal direction, . - a data processing unit, Which selects the appropriate gear ratio on the basis of incoming parameters and communicates directly with the gearbox or with a control unit that controls the gearbox, characterised in that each shift fork is separately attached to the shift shaft and equipped with a controllable locking device and in the event of an ingoing signal to the gearbox from the control unit and/or the data processing unit can be guided alternately between a first position where the shift fork is locked to the shift shaft, thereby following the shift shaft's movement, and a second position where the shift fork is not locked to the shift shaft and the shift shaft can be moved relative to the shift fork, one shift fork at a time being locked to the shift shaft while the rest are not locked, and on movement of the shift shaft the shift fork which is locked to the shift shaft causes shifting to a new gear ratio.

6. A system for implementing a gearshift according to one of the claims 1-5, characterised in that the shift shaft is movable in its longitudinal direction.

7. A system for implementing a gearshift according to one of the claims 1-6, characterised in that each shift fork is provided with a mounting portion with a through-going bore and the shift shaft is passed through the bore(s).

8. A system for implementing a gearshift according to one of the claims 1-7, characterised in that the shift shaft is provided with an opening and the mounting portion is provided with an opening, where the shift fork's locking device comprises a locking pin that causes locking of the shift fork to the shift shaft by a portion of the locking pin being received in the shift shaft's opening and a portion in the mounting portion's opening.

9. A system for implementing a gearshift according to claim -^ characterised in that the shift shaft's opening is through-going in the shift shaft's diametrical direction, preferably with a length that at least corresponds to the shift shaft's diameter, and that the shift fork's mounting portion is provided with a locking groove for receiving a portion of the locking pin when the shift fork has to be locked to the shift ^" shaft.

10. A system for implementing a gearshift according to claim ji_j, characterised in that a spring-loaded return device is mounted in the locking groove.

11. A system for implementing a gearshift according to one of the .claims 9- 10, characterised in that the mounting portion's opening is in the form of a through-going opening and positioned over the shift shaft's through- going opening and aligned therewith, the locking device's locking pin having a length which is such that the locking pin extends through the mounting portion's through-going opening and the shift shaft's through- going opening, or that the locking device further comprises a locking- initiating device extending through the mounting portion's through-going opening to abut against the locking pin, where in both cases the locking pin is suitable to be received in the mounting portion's locking groove.

12. A system for implementing a gearshift according to one of the claims 9- 11, characterised in that the locking device further comprises an activating element which is provided on the shift fork's mounting portion, activation of the activating element causing movement of the locking- initiating device or the locking pin through the mounting portion's through-going opening and movement of the locking pin in the shift shaft, with the result that a portion of the locking pin is received in the locking groove and the shift fork is locked.

13. A system for implementing a gearshift according to one of the claims 9- 11, characterised in that the locking device further comprises an activating element which is provided on the shift fork's mounting portion, activation of the activating element causing withdrawal of the locking- initiating device or the locking pin through the mounting portion's through-going opening, and thereby a possible movement of the locking pin in the shift shaft, with the result that a portion of the locking pin is removed from the locking groove and the shift fork is unlocked.

14. A system for implementing a gearshift according to claim 12, characterised in that the locking-initiating device or the locking pin is prestressed by a spring and deactivation of the activating element results in withdrawal of the locking pin from the locking groove by means of the spring's pre-tensioning force.

15. A system for implementing a gearshift according to claim 13, characterised in that the locking-initiating device or the locking pin is held in a locked position by a spring and activation of the activating element results in the establishment of a force with a direction that overcomes the spring's force, thereby causing the locking pin to be withdrawn from the locking groove.

16. A system for implementing a gearshift according to one of the claims 12- 15, characterised in that the activating element is composed of a solenoid, the solenoid's movable core being magnetic and constituting the locking pin or the locking-initiating device and that a coil encircles the spring.

17. A system for implementing a gearshift according to one of the claims 12- 15, characterised in that the activating element is composed of a cylinder with a piston which, for example, is hydraulically or pneumatically controlled, a portion of the piston constituting the locking pin or the locking-initiating device.