SE1950021A1 - A gearbox for a vehicle and a vehicle comprising such a gearbox - Google Patents

Abstract

The invention relates to a gearbox (4) for a vehicle (1), the gearbox (4) comprising an input shaft (12) adapted to be connected to a propulsion unit (6); a main shaft (16) connectable to the input shaft (12); a first range gear group (RG1) connected to the main shaft (16); an output shaft (21) connectable to the first range gear group (RG1); a first gear pair (G1) connectable to the input shaft (12); a second gear pair (G2) connectable to the main shaft (16); and a lay shaft (22) connectable to the first gear pair (G1) and to the second gear pair (G2). A third gear pair (G3) is connectable to the input shaft (12) and the lay shaft (22), wherein the third gear pair (G3) together with the first gear pair (G1) represent gear steps in a main gear group (MG) in the gearbox (4), and wherein the third gear pair (G3) together with the second gear pair (G2) represent a second range gear group (RG2) in the gearbox (4). The invention also relates to vehicle (1) comprising such a gearbox (4).

Description

A gearbox for a vehicle and a vehicle comprising such a gearbox TECHNICAL FIELD The invention relates to a gearbox for a vehicle according to the appendedclaims. The invention further relates to a vehicle according to the appended claims.

BACKGROUND Vehicles, and in particular heavy goods vehicles, such as trucks, are usuallyequipped with a gearbox connected to the combustion engine, which gearboxmay be automatic, manual or a combination thereof. ln an automated manualtransmission, a so-called Al\/lT gearbox, the gearbox is controlled by an elec-tronic control device. Such a gearbox may be equipped with a main gearboxdevice provided with a main shaft. A lay shaft is arranged in parallel to themain shaft. The main shaft is connectible to an input shaft via the lay shaft andto an output shaft in the gearbox via a range gearbox device, if such a rangegearbox device is integrated in the gearbox. The range gearbox device mayconstitute a separate device instead of being integrated in the gearbox. Thegearbox may also be equipped with a split gear device, arranged between theinput shaft and the lay shaft. ln gearboxes of this type, the synchronization devices, comprising conical syn-chronization rings and coupling rings, are replaced by coupling sleeves provid-ed with splines, which are displaced axially in order to engage with gearwheelsplaced on the main shaft. Each gearwheel placed on the main shaft is en-gaged with corresponding gearwheel elements, which are firmly attached tothe lay shaft. On shifting, the coupling sleeve is displaced axially in order toengage with coupling teeth arranged on a selectable gearwheel, in order to connect the gearwheel to, and rotation lock it, on the main shaft.

The range gearbox device is usually provided between the main gearbox de-vice and a propeller shaft coupled to the drive wheels of the vehicle. The rangegearbox device is accommodated in a gearbox housing and comprises an in-put shaft coupled to the main gearbox device, an output shaft and between theinput shaft and the output shaft is a planetary gear of the range gearbox devicedisposed. The planetary gear usually comprises three components, which arerotatable arranged relative to each other namely a sun gear, a planet carrierwith planet gears and a ring gear. With knowledge of the number of teeth ofthe sun gear and the ring gear the relative speed of the three components canbe determined during operation. ln a range gearbox device the sun gear canbe rotatable connected to the input shaft, a number of planet gears which en-gage said sun gear, which planet gears are rotatable mounted on the planetcarrier which is connected to the output shaft, and an axially displaceable ringgear which surrounds and engages the planet gears.

By controlling the transmission to synchronous speed between the two com-ponents to be assembled an axial displacement of the coupling sleeve alongthe two components is made possible in order to connect them. When thecomponents should be detached the transmission is controlled so that torquebalance occurs between the components so that the coupling sleeve is nottransmitting torque. lt then becomes possible to move the coupling sleeve axi-ally along the components in order to disengage them from each other.

The torque balance is a condition where a torque acting on the ring gear, cor-responding to the product of the torque acting on the planet carrier and thegear ratio of the planetary gear while a torque acts on the sun gear, corre-sponding to the product of the torque acting on the planet carrier and (1 -thegear ratio of the planetary gear). ln the case that two of the components of theplanetary gear, sun gear, ring gear or planet carrier, are coupled together by acoupling sleeve, the coupling sleeve transmits no torque between the plane-tary gear elements when torque balance occurs. Thus, the coupling sleeve canbe easily displaced and the planetary gear components released.

Document US2015/O345603A1 relates to motor vehicle transmission havingtwo sub-transmissions, each with an input shaft. The input shafts are arrangedon an input side on an input axis. The two sub-transmissions have a singleoutput shaft. A lay shaft assembly having two lay shafts aligned on a counter-shaft axis. A main shaft arranged on the input axis can be connected, viarange groups, to the output shaft. At least one of the input shafts can connectto the output shaft via at least one of a gear plane, a shift element and themain shaft. Three shift devices are arranged with at most one of the shift de-vices is arranged on the lay shaft axis. The first three shift devices are ar-ranged, relative to torque flow, downstream of the input side of the transmis- sion on the input axis.

SUMMARY Despite prior art, there is a need to develop a gearbox for a vehicle, whichgearbox has small dimensions and which requires a small amount of energy ina powertrain of a vehicle. There is also a need to develop a gearbox for a ve- hicle, in which gearbox components are effectively used.

The object of the invention is thus to provide a gearbox for a vehicle, whichgearbox has small dimensions and which requires a small amount of energy in a powertrain of a vehicle.

A further object of the invention is to provide a gearbox for a vehicle, in whichgearbox components are effectively used.

Another object of the invention is to provide a vehicle, comprising such a gear-box.

The herein mentioned objects are achieved with a gearbox for a vehicle ac-cording to the appended claims. The herein mentioned objects are also achieved with a vehicle according to the appended claims.

According to an aspect of the invention, a gearbox for a vehicle is provided.The gearbox comprising: an input shaft adapted to be connected to a propul-sion unit; a main shaft connectable to the input shaft; a first range gear groupconnected to the main shaft; an output shaft connectable to the first range geargroup; a first gear pair connectable to the input shaft; a second gear pair con-nectable to the main shaft; and a lay shaft connectable to the first gear pairand to the second gear pair, wherein the gearbox further comprising: a thirdgear pair connectable to the input shaft and the lay shaft, wherein the thirdgear pair together with the first gear pair represent gear steps in a main geargroup in the gearbox, and wherein the third gear pair together with the second gear pair represent a second range gear group in the gearbox.

According to a further aspect of the invention, a vehicle is provided, wherein the vehicle comprises such a gearbox.

This gearbox has small dimensions and requires a small amount of energy in apowertrain of a vehicle. ln addition, in such gearbox components are effective-ly used. The vehicle, comprising such a gearbox, will benefit from reduced fuelconsumption because of the small amount of energy required in the powertrainof the vehicle and due to the effectively use of the gearbox components.

The first and second range gear group will provide the gearbox with a pluralityof selectable gear steps and gear combinations for the third gear pair togetherwith the first gear pair in the main gear group of the gearbox. This will increasethe drivability of the vehicle and increase the comfort for passengers in the ve- hicle.

Since the third gear pair and the first gear pair together represent gear steps inthe main gear group, and the third gear pair and the second gear pair togetherrepresent a second range gear group, the third gear pair is effectively used fordifferent purposes in the gearbox. Since third gear pair is connectable to theinput shaft and the |ay shaft, this flexibility is made possible. The connectablethird gear pair provides a connection and a disconnection of the third gear pairon the input shaft and on the |ay shaft. Thus, depending on the driving condi-tions of the vehicle, the third gear pair may be connected or disconnected fromthe input shaft or the |ay shaft in order to be a part of the gear steps in themain gear group or be a part of the second range gear group.

Additional objectives, advantages and novel features of the invention will beapparent to one skilled in the art from the following details, and through exer-cising the invention. While the invention is described below, it should be ap-parent that the invention may not be limited to the specifically described de-tails. One skilled in the art, having access to the teachings herein, will recog-nize additional applications, modifications and incorporations in other areas,which are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Below is a description of, as examples, preferred embodiments with referenceto the enclosed drawings, in which: Figure 1 schematically illustrates a vehicle provided with a gearbox according to an embodiment; Figure 2 schematically illustrates a gearbox according to an embodiment; and Figure 3 schematically illustrates a gearbox according to an embodiment.

DETAILED DESCRIPTION The gearbox, according to the present disclosure, has small dimensions andrequires a small amount of energy in a powertrain of a vehicle. ln addition, thecomponents in the gearbox are effectively used. The vehicle, comprising sucha gearbox, will benefit from reduced fuel consumption because of the smallamount of energy required in the powertrain of the vehicle and due to the ef-fectively use of the gearbox components.

According to an aspect, the present disclosure relates to a gearbox for a vehi-cle, the gearbox comprising: an input shaft adapted to be connected to a pro-pulsion unit; a main shaft connectable to the input shaft; a first range geargroup connected to the main shaft; an output shaft connectable to the firstrange gear group; a first gear pair connectable to the input shaft; a secondgear pair connectable to the main shaft; and a lay shaft connectable to the firstgear pair and to the second gear pair, wherein the gearbox further comprising:a third gear pair connectable to the input shaft and the lay shaft, wherein thethird gear pair together with the first gear pair represent gear steps in a maingear group in the gearbox, and wherein the third gear pair together with thesecond gear pair represent a second range gear group in the gearbox.

The gearbox is adapted for a vehicle. The vehicle may be any type of vehicle.Thus, the vehicle may be a heavy goods vehicle, such as a truck or a bus. Thegearbox comprises an input shaft, which is adapted to be connected to a pro-pulsion unit. The propulsion unit may be an internal combustion engine or anelectrical machine or a combination thereof. A controllable clutch may be ar-ranged between the propulsion unit and the input shaft of the gearbox, so thatthe propulsion unit may be disconnected from the gearbox during certain driv-ing conditions, such as idle, gear shifting or start-up of the propulsion unit. Themain shaft may be connectable to the input shaft by means of a bearing, sothat the input shaft and the main shaft may rotate at different speeds in relation to each other. The output shaft may be connectable to the first range geargroup. The first range gear group may double the available gear steps in thegearbox. The output shaft may transmit torque from the first range gear groupin the gearbox to, for example, wheels of the vehicle. The first gear pair is con-nectable to the input shaft and to the lay shaft. The second gear pair is con-nectable to the main shaft and to the lay shaft. The third gear pair is connecta-ble to the input shaft and the lay shaft. The definition of connectable in thiscontext is that the gear pairs may be connected to and disconnected from therespective shaft. The third gear pair together with the first gear pair representgear steps in a main gear group in the gearbox. According to one example, thefirst gear pair may transfer torque and rotational speed from the input shaft tothe lay shaft. The third gear pair may transfer that torque and rotational speedfrom the lay shaft further to the main shaft. According to another example, thethird gear pair may transfer torque and rotational speed from the input shaft tothe lay shaft. The second gear pair may transfer that torque and rotationalspeed from the lay shaft further to the main shaft. According to a further exam-ple, the third gear pair may be disconnected from the input shaft and/or the layshaft. Torque and rotational speed may according this further example betransferred from the input shaft to the lay shaft by means of the first gear pair.The second gear pair may transfer that torque and rotational speed from thelay shaft further to the main shaft. The third gear pair together with the second gear pair represent a second range gear group in the gearbox. ln the situation when the second gear pair is connected to the main shaft andthe lay shaft, and the third gear pair is disconnected from the main shaft, thesecond range gear group is shifted to a low range gear position. ln the low range gear position a down shift takes place in the second range gear group. ln the situation when the second gear pair is disconnected from the main shaftand/or the lay shaft, and the third gear pair is connected to the main shaft, the second range gear group is shifted to a high range gear position. ln the high range gear position the gear ratio is 1:1 or an up-shift takes place in the sec-ond range gear group.

The first and second range gear group will provide the gearbox with a p|ura|ityof selectable gear steps and gear combinations for the third gear pair togetherwith the first gear pair in the main gear group of the gearbox. This will increasethe drivability of the vehicle and increase the comfort for passengers in the ve-hicle.

Since the third gear pair and the first gear pair together represent gear steps inthe main gear group, and the third gear pair and the second gear pair togetherrepresent a second range gear group, the third gear pair is effectively used fordifferent purposes in the gearbox. Since third gear pair is connectable to theinput shaft and the |ay shaft, this flexibility is made possible. The connectablethird gear pair provides a connection and a disconnection of the third gear pairon the input shaft and/or on the |ay shaft. Thus, depending on the driving con-ditions of the vehicle, the third gear pair may be connected or disconnectedfrom the input shaft and/or the |ay shaft in order to be a part of the gear steps in the main gear group or be a part of the second range gear group.

According to an aspect, the third gear pair comprises a third gear wheel, whichis connectable to and disconnectable from the input shaft.

The third gear wheel may be connected to and disconnected from the inputshaft by means of a third axially displaceable sleeve, which is provided withsplines. The splines of the sleeve is configured to connect with correspondingsplines on the third gear wheel and the input shaft when connecting the thirdgear wheel to the input shaft. The third axially displaceable sleeve is config-ured to transfer torque. Connecting the third gear wheel to the input shaftmeans that a gear in the gearbox is engaged. Before connecting the third gearwheel to the input shaft the rotational speed of the third gear wheel and the input shaft are synchronized. Thereafter the sleeve is axially displaced to en- gage with the splines of the third gear wheel. When disconnecting the thirdgear wheel and the input shaft, and thus disengaging a gear in the gearbox,the third axially displaceable sleeve is displaced in the axially direction of theinput shaft and thus disengaging the splines of the sleeve from the splines ofthe third gear wheel. Before disconnecting the third gear wheel from the inputshaft, torque balance between the third gear wheel and the input shaft is gen-erated. When the third axially displaceable sleeve no longer transfer torquebetween the third gear wheel and the input shaft, the sleeve may be displacedaxially in order to disconnect the third gear wheel from the input shaft.

According to an aspect, the third gear wheel is rotatably arranged in relation tothe input shaft.

When the third gear wheel is disconnected from the input shaft, the third gearwheel is free to rotate in relation to the input shaft. A suitably bearing or bear-ings may be arranged between the third gear wheel and the input shaft in or-der to reduce the friction and heat generation between the third gear wheeland the input shaft when the third gear wheel rotates in relation to the inputshaft. When the third gear wheel is connected to the input shaft, the third gearwheel and the input shaft will rotate with equal speed. Torque may be trans-ferred between the third gear wheel and the input shaft when the third gearwheel is connected to the input shaft. When the third gear wheel is discon-nected from the input shaft no torque may be transferred between the thirdgear wheel and the input shaft. The input shaft may rotate with a rotationalspeed and the third gear wheel may rotate with another rotational speed whenthe third gear wheel is disconnected from the input shaft. This is possible since the third gear wheel may be driven by the lay shaft via the third gear pair.

According to an aspect, the third gear wheel is configured to be connected tothe main shaft in a high range gear position of the second range gear group. ln the situation when the third gear pair is connected to the main shaft, thesecond range gear group is shifted to a high range gear position. ln the highrange gear position the gear ratio may be 1:1. Alternatively, in the high rangegear position an up-shift takes place in the second range gear group. ln thehigh range gear position the second gear pair is disconnected from the mainshaft and/or the lay shaft.

The third gear wheel may be connected to and disconnected from the mainshaft by means of a second axially displaceable sleeve, which is provided withsp|ines. The sp|ines of the sleeve is configured to connect with correspondingsp|ines on the third gear wheel and the input shaft when connecting the thirdgear wheel to the main shaft. The second axially displaceable sleeve is config-ured to transfer torque. Connecting the third gear wheel to the main shaftmeans that the second range gear group is shifted to a high range gear posi-tion. Before connecting the third gear wheel to the main shaft the rotationalspeed of the third gear wheel and the main shaft are synchronized. Thereafterthe sleeve is axially displaced to engage with the sp|ines of the third gearwheel. When disconnecting the third gear wheel from the main shaft, and thusshifting the second range gear group to a low range gear position, the secondaxially displaceable sleeve is displaced in the axially direction of the main shaftand thus disengaging the sp|ines of the sleeve from the sp|ines of the thirdgear wheel. Before disconnecting the third gear wheel from the main shaft,torque balance between the third gear wheel and the main shaft is generated.When the second axially displaceable sleeve no longer transfer torque be-tween the third gear wheel and the main shaft, the sleeve may be displacedaxially in order to disconnect the third gear wheel from the main shaft.

According to an aspect, the second gear pair comprises a second gear wheel,which is connectable to and disconnectable from the main shaft.

The second gear wheel may be connected to and disconnected from the mainshaft by means of the second axially displaceable sleeve, which is provided 11 with sp|ines. The sp|ines of the sleeve is configured to connect with corre-sponding sp|ines on the second gear wheel and the main shaft when connect-ing the second gear wheel to the main shaft. The second axially displaceablesleeve is configured to transfer torque. Connecting the second gear wheel tothe main shaft means that a low range gear position in the second range groupis shifted. Before connecting the second gear wheel to the main shaft the rota-tional speed of the second gear wheel and the main shaft are synchronized.Thereafter the sleeve is axially displaced to engage with the sp|ines of thesecond gear wheel. When disconnecting the second gear wheel and the mainshaft, and thus shifting the second range group to a high range gear position,the second axially displaceable sleeve is displaced in the axially direction ofthe main shaft and thus disengaging the sp|ines of the sleeve from the sp|inesof the second gear wheel. Before disconnecting the second gear wheel fromthe main shaft, torque balance between the second gear wheel and the mainshaft is generated. When the second axially displaceable sleeve no longertransfer torque between the second gear wheel and the main shaft, the sleevemay be displaced axially in order to disconnect the second gear wheel fromthe main shaft.

The second axially displaceable sleeve, which is configured to connect anddisconnect the second gear wheel to and from the main shaft may be thesame sleeve, which is configured to connect and disconnect the third gear wheel to and from the main shaft.

According to an aspect, the second gear wheel is rotatably arranged in relationto the main shaft.

When the second gear wheel is disconnected from the main shaft, the secondgear wheel is free to rotate in relation to the main shaft. A suitably bearing orbearings may be arranged between the second gear wheel and the main shaftin order to reduce the friction and heat generation between the second gearwheel and the main shaft when the second gear wheel rotates in relation to the 12 main shaft. When the second gear wheel is connected to the main shaft, thesecond gear wheel and the main shaft will rotate with equal speed. Torquemay be transferred between the second gear wheel and the main shaft whenthe second gear wheel is connected to the main shaft. When the second gearwheel is disconnected from the main shaft no torque may be transferred be-tween the second gear wheel and the main shaft. The main shaft may rotatewith a rotationa| speed and the second gear wheel may rotate with anotherrotationa| speed when the second gear wheel is disconnected from the mainshaft. This is possible since the second gear wheel may be driven by the |ayshaft via the second gear pair.

According to an aspect, a first bearing is arranged between the main shaft anda gearbox housing of the gearbox in a position between the first and second range gear groups.

The main shaft is connected to the first and second range gear groups. ln aposition between the first and second range gear groups the main shaft is ro-tatably arranged in relation to the gearbox housing by means of a bearing. Thisarrangement will provide stability to the main shaft, which will result in that themain shaft may be designed with small dimensions and low weight. The firstbearing may be a ball bearing.

According to an aspect, a second bearing is arranged between the input shaftand the main shaft.

The main shaft may be rotatably connected to the input shaft by means of abearing, so that the input shaft and the main shaft may rotate at differentspeeds in relation to each other. This is suitable since rotationa| speed andtorque from the input shaft may be transferred to the |ay shaft via the first orthe third gear pairs and further to the main shaft via the second gear pairs.Since the gear ratios of the first, second and third gear pairs may be different,the rotationa| speed of the input and main shafts may be different. When a 13 second bearing is arranged between the input and main shaft, they may rotatewith different rotational speeds in relation to each other. The second bearing may be a ball bearing.

According to an aspect, the second bearing is arranged radially inside the firstbeanng.

The first and second bearings may be arranged at the same axial positionalong the input and main shafts. The second bearing is arranged radially insidethe first bearing. As a result, bending forces acting on the input shaft shouldmainly be transferred through the first and second bearings as radially directedforces. Therefore, the first and second bearings may be designed with reduceddimensions comparing to a situation in which the bending forces from input shaft results in both radially and axially forces on the bearings.

According to an aspect, the input shaft is adapted to extend in one piece froma first end part of the input shaft, which is configured to be arranged outside agearbox housing of the gearbox to a second end part of the input shaft, whichis configured to be rotatably connected to the main shaft in an position be-tween the first and second range gear groups.

Such an input shaft extend almost completely through the gearbox in onepiece. This will result in an input shaft with a reduced diameter comparing to ashaft made of several pieces. The stability of the gearbox increases due to theinput shaft made in one piece. Bearings between the gearwheels that are ro-tatably arranged on the input shaft may be arranged with a reduced diameter.

This will increase the efficiency of the gearbox.

According to an aspect, the first range gear group is a planetary gear, which isshiftable between a low range gear position, a high range gear position and a reverse gear position. 14 A planetary gear may be designed with small dimensions and still the plane-tary gear may provide a large gear ratio. ln addition, the planetary gear mayhave low weight and still provide a large gear ratio. The small dimensions andlow weight of the planetary gear may reduce the over all dimensions of thegearbox and also reduce the fuel consumption of the propulsion source con-nected to the gearbox. ln addition to the high and low range gear positions, theplanetary gear may be provided with a reverse position. When the planetarygear is shifted to the reverse position, the output shaft rotates in the oppositedirection comparing to the rotational direction when the planetary gear is shift-ed to the high and low range gear positions.

According to a further aspect, the present disclosure also relates to a vehicle,wherein the vehicle comprises the above-mentioned gearbox.

Such a vehicle provided with the gearbox may increase the drivability of thevehicle and increase the comfort for passengers in the vehicle. ln addition, thefuel consumption of the propulsion unit connected to the gearbox in the vehiclemay be reduced.

The present disclosure will now be further illustrated with reference to the ap- pended figures.

Figure 1 shows schematically a side view of a vehicle 1, e.g. a truck, with apowertrain 2 provided with a gearbox 4 according to an embodiment. Thepowertrain 2 also comprises a propulsion unit 6, such as an internal combus-tion engine, which is connected to the gearbox 4. The gearbox 4 is further connected to driving wheels 8 of the vehicle 1 via a propeller shaft 10.

Figure 2 schematically illustrates a gearbox 4 according to an embodiment.The gearbox 4 comprises an input shaft 12, which is adapted to be connectedto the propulsion unit 6 by means of a controllable clutch 14. A main shaft 16 isconnectable to the input shaft 12. A first range gear group RG1 is connected to the main shaft 16. The first range gear group RG1 is a planetary gear 19,which is shiftable between a low range gear position and a high range gearposition. An output shaft 21 is connectable to the first range gear group RG1.A first gear pair G1 is connected to the input shaft 22. The first gear pair G1 isconnectable to a |ay shaft 22 by means of a first axially displaceable sleeve 18.A second gear pair G2 connectable to the main shaft 16 by means of a secondaxially displaceable sleeve 20. The |ay shaft 22 is to the second gear pair G2.A third gear pair G3 is connectable to the input shaft 12 by means of a thirdaxially displaceable sleeve 24 and connected to the |ay shaft 22. The thirdgear pair G3 and the first gear pair G1 represent a main gear group MG in thegearbox 4. The main gear group l\/lG also comprises a fourth gear pair G4. Thefourth gear pair G4 is connectable to the input shaft 12 by means of the thirddisplaceable sleeve 24. The fourth gear pair G4 is also connected to the |ayshaft 22. The third gear pair G3 and the second gear pair G2 represent a sec- ond range gear group RG2 in the gearbox 4.

The input shaft 12 is adapted to extend in one piece from a first end part 26 ofthe input shaft 12, which is configured to be arranged outside a gearbox hous-ing 27 of the gearbox 4 to a second end part 28 of the input shaft 12, which isconfigured to be rotatably connected to the main shaft 16 in an position be-tween the first and second range gear groups RG1, RG2.

The third gear pair G3 comprises a third gear wheel 30, which is connectableto and disconnectable from the input shaft 12. The third gear wheel 30 is con-nected to and disconnected from the input shaft 12 by means of the first axiallydisplaceable sleeve 18. The third gear wheel 30 is rotatably arranged in rela-tion to the input shaft 12.

The planetary gear 19 comprises a ring gear wheel 32, a sun gear wheel 34and a planet gear wheel carrier 36, on which planet gear wheels 38 are rotata-b|y mounted. The main shaft 16 is connected to the sun gear wheel 34. Theplanet gear wheel carrier 36 is connected to the output shaft 21. ln a low range 16 gear position, the ring gear wheel 32 and the gearbox housing 27 may be en-gaged to each other by means of a fourth axially displaceable sleeve 40. ln ahigh range gear position, the ring gear wheel 32 and the planet gear wheelcarrier 36 may be engaged to each other by means of the fourth axially dis-placeable sleeve 40.

The axial displacement of the axially displaceable sleeves 18, 20, 24, 40 areprovided with a respective shift fork 42 arranged in connection the individuallysleeves 18, 20, 24, 40. The shift forks 42 are controlled by individually powermeans 44, such as a pneumatic, hydraulic or electric cylinders.

The third gear wheel 30 is configured to be connected to the main shaft 16 in ahigh range gear position of the second range gear group RG2. The secondgear pair G2 comprises a second gear wheel 46, which is connectable to anddisconnectable from the main shaft 16. The second gear wheel 46 is rotatablyarranged in relation to the main shaft 16. The second gear wheel 46 is con-nected to and disconnected from the main shaft 16 by means of the secondaxially displaceable sleeve 20.

A first bearing 48 is arranged between the main shaft 16 and a gearbox hous-ing 27 of the gearbox 4 in a position between the first and second range geargroups RG1, RG2. A first bearing is arranged between the input shaft 12 andthe main shaft 16. The second bearing 50 is arranged radially inside the firstbearing 48.

An electronic control device 52 is coupled to the gearbox 4, the propulsion unit6 and to the clutch 14. The control device 52 controls the gear shifting in thegearbox 4. The control device 52 may be a computer with appropriate softwarefor this purpose. A number of not shown speed sensors in the gearbox 4 andin the propulsion unit 6 may be connected to the control device 52 The controldevice 52 comprise a computer program P, which can include routines to con- trol the gearbox 4 of the present disclosure. The program P may be stored in 17 an executable form or compressed form in a memory l\/I and/or in a read/writememory. A computer program product may be provided, comprising a programcode stored on a, by a computer readable medium for performing gear shift-ings in the gearbox 4, when said program is run on the control device 52. Saidcode may be non-volatile, stored in said computer readable medium.

Figure 3 schematically i||ustrates a gearbox 4 according to an embodiment.The second range gear group RG2 in the gearbox 4 is similar to the secondrange gear group RG2 shown in fig. 2. However, in addition to the first, thirdand fourth gear pairs G1, G3, G4 in the main gear group lVlG shown in fig. 2,the main gear group IVIG shown in fig. 3 also comprises a fifth gear pair G5.The fifth gear pair G5 is connected to the input shaft 12 and connectable to thelay shaft 22 by means of the first axially displaceable sleeve 18.

The first range gear group RG1 comprises a planetary gear 19, which shiftablebetween a low range gear position, a high range gear position and also a re- verse gear position. When the planetary gear 19 is shifted to the reverse posi-tion, the output shaft 21 rotates in the opposite direction comparing to the rota-tional direction when the planetary gear 19 is shifted to the high and low range gear positions.

The planetary gear 19 in the first range gear group RG1 comprises a ring gearwheel 32, a sun gear wheel 34 and a planet gear wheel carrier 36, on whichplanet gear wheels 38 are rotatably mounted. The ring gear wheel 32 and sungear wheel 34 are configured to engage with the planet gear wheels 38. Thegearbox housing 27 surrounds the planetary gear 19. A fifth axially displacea-ble sleeve 54 is arranged for selectively engaging and disengaging the ringgear wheel 32 with/from the gearbox housing 27 and for selectively engagingand disengaging the ring gear wheel 32 and the planet gear wheel carrier 36with/from each other. A sixth axially displaceable sleeve 56 is arranged for se-lectively engaging and disengaging the output shaft 21 with/from the ring gearwheel 32 and with/from the planet gear wheel carrier 36. A seventh axially dis- 18 placeable sleeve 58 is arranged for selectively engaging and disengaging thesun gear wheel 34 with/from the planet gear wheel carrier 36. The fifth axiallydisplaceable sleeve 54 is in a low range gear position configured to engagethe ring gear wheel 32 with the gearbox housing 27, and in a high range gearposition configured to disengage the ring gear wheel 32 from the gearboxhousing 27. The sixth axially displaceable sleeve 56 is in both the low and highrange gear positions configured to engage the planet gear wheel carrier 36with the output shaft 21. The seventh axially displaceable sleeve 58 is in thelow range gear wheel position configured to disengage the sun gear wheel 34from the planet gear wheel carrier 36, and in high range gear position config- ured to engage the sun gear wheel 34 with the planet gear wheel carrier 36. ln the reverse gear position, the fifth axially displaceable sleeve 54 is config-ured to engage the planet gear wheel carrier 36 with the gearbox housing 27,the sixth axially displaceable sleeve 56 is configured to engage the ring gearwheel 32 with the output shaft 21, and the seventh axially displaceable sleeve58 is configured to disengage the sun gear wheel 34 from the planet gearwheel carrier 36.

The fifth, sixth and seventh axially displaceable sleeves 54, 55, 58 are axiallydisplaced by individually arranged shift forks 42, arranged in connection withthe axially displaceable sleeves 54, 55, 58. The shift forks 42 are controlled by power means 44, such as a pneumatic, hydraulic or electric cylinders The foregoing description of the embodiments has been furnished for illustra-tive and descriptive purposes. lt is not intended to be exhaustive, or to limit theembodiments to the variants described. l\/lany modifications and variations willobviously be apparent to one skilled in the art. The embodiments have beenchosen and described in order to best explicate principles and practical appli-cations, and to thereby enable one skilled in the art to understand the embod-iments in terms of its various embodiments and with the various modifications that are applicable to its intended use. The components and features specified 19 above may, within the framework of the embodiments, be combined betweendifferent embodiments specified.

Claims (12)

CLAIIVIS

1. A gearbox (4) for a vehicle (1), the gearbox (4) comprising:an input shaft (12) adapted to be connected to a propulsion unit(6);a main shaft (16) connectabie to the input shaft (12);a first range gear group (RG1) connected to the main shaft (16);an output shaft (21) connectabie to the first range gear group(RG1);a first gear pair (G1) connectabie to the input shaft (12);a second gear pair (G2) connectabie to the main shaft (16); anda Iay shaft (22) connectabie to the first gear pair (G1) and to thesecond gear pair (G2),wherein the gearbox (4) further comprising:a third gear pair (G3) connectabie to the input shaft (12) and theIay shaft (22), wherein the third gear pair (G3) together with the first gear pair(G1) represent gear steps in a main gear group (I\/IG) in the gearbox (4), andwherein the third gear pair (G3) together with the second gear pair (G2) repre- sent a second range gear group (RG2) in the gearbox (4).

2. The gearbox (4) according to c|aim 1, wherein the third gear pair (G3) com-prises a third gear wheel (30), which is connectabie to and disconnectable from the input shaft (12).

3. The gearbox (4) according to c|aim 2, wherein the third gear wheel (30) isrotatabiy arranged in relation to the input shaft (12).

4. The gearbox () according to any one of c|aims 2 and 3, wherein the thirdgear wheel (30) is configured to be connected to the main shaft (16) in a high range gear position of the second range gear group (RG2). 21

5. The gearbox (4) according to any one of the preceding claims, wherein thesecond gear pair (G2) comprises a second gear wheel (46), which is connect- able to and disconnectable from the main shaft (16).

6. The gearbox (4) according to claim 5, wherein the second gear wheel (46) isrotatab|y arranged in relation to the main shaft (16).

7. The gearbox (4) according to any one of the preceding claims, wherein afirst bearing (48) is arranged between the main shaft (16) and a gearbox hous-ing (27) of the gearbox (4) in a position between the first and second rangegear groups (RG1, RG2).

8. The gearbox (4) according to any one of the preceding claims, wherein asecond bearing (50) is arranged between the input shaft (12) and the mainshaft (16).

9. The gearbox (1) according to claims 7 and 8, wherein the second bearing(50) is arranged radia||y inside the first bearing (48).

10. The gearbox (4) according to any of the preceding claims, wherein the in-put shaft (12) is adapted to extend in one piece from a first end part (26) of theinput shaft (12), which is configured to be arranged outside a gearbox housing(27) of the gearbox (4) to a second end part (28) of the input shaft (12), whichis configured to be rotatab|y connected to the main shaft (16) in an positionbetween the first and second range gear groups (RG1, RG2).

11. The gearbox (4) according to any one of the preceding claims, wherein thefirst range gear group (RG1) is a p|anetary gear (19), which is shiftable be-tween a low range gear position, a high range gear position and a reverse gear position. 22

12. A vehicle (1 ), wherein the vehicle (1) comprises a gearbox (4) according toany one of the preceding claims.