SE1950020A1 - A method, performed by a control device, for shifting gears in a gearbox - Google Patents

Abstract

The invention relates to a method, performed by a control device (100), for shifting gears in a gearbox (4). 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); a lay shaft (22) connectable to the first gear pair (G1) and to the second gear pair (G2), and a third gear pair (G3) connectable to the input shaft (12), the main shaft (16) and the lay shaft (22). The method comprising: connecting (s101) the second gear pair (G2) to the main shaft (16); disconnecting (s102) the third gear pair (G3) from the input shaft (12) and from the main shaft (16); and connecting (s103) the first gear pair (G1) to the input shaft (12) and with the lay shaft (22). The invention also relates to computer program (P) and computer-readable medium.

Description

A method, performed by a control device, for shifting gears in a gearbox TECHNICAL FIELD The invention relates to a method, performed by a control device, for shiftinggears in a gearbox according to the appended claims. The invention furtherrelates to computer program and computer-readable medium 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 the input 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 toconnect 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 ring gear, 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 a coupling 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 energywhen shifting gears in the gearbox. There is also a need to develop a gearboxfor a vehicle, in which gearbox components are effectively used.

The object of the invention is thus to provide a new and advantageous methodfor shifting gears in a gearbox, which gearbox has small dimensions and whichrequires a small amount of energy when shifting gears in the gearbox.

A further object of the invention is to provide a new and advantageous methodfor shifting gears in a gearbox, in which components in the gearbox are effec- tively used.

The herein mentioned objects are achieved with a method for shifting gears ina gearbox according to the appended claims, which gearbox has small dimen- sions and which requires a small amount of energy when shifting gears in thegearbox. The herein mentioned objects are also achieved with a method forshifting gears in a gearbox according to the appended claims, in which gear-box the components in the gearbox are effectively used.

According to an aspect of the invention, a method, performed by a control de-vice, for shifting gears in a gearbox is provided. The gearbox comprising: aninput shaft adapted to be connected to a propulsion unit; a main shaft con-nectable to the input shaft; a first range gear group connected to the mainshaft; an output shaft connectable to the first range gear group; a first gear pairconnectable to the input shaft; a second gear pair connectable to the mainshaft; a lay shaft connectable to the first gear pair and to the second gear pair,and a third gear pair connectable to the input shaft, the main shaft and the layshaft. The method comprising: connecting the second gear pair to the mainshaft; disconnecting the third gear pair from the input shaft and from the mainshaft; and connecting the first gear pair to the input shaft and with the lay shaft.

According to a further aspect of the invention, a computer program is provided,According to a further aspect of the invention, a computer-readable medium isprovided.

Such method provides for shifting gears in a gearbox, which shifting requires asmall amount of energy when gears are shifted in the gearbox. ln addition,method provides for shifting gears in a gearbox, in which gearbox the compo-nents in the gearbox are effectively used when shifting gears.

When the gearbox is arranged in a vehicle and gears are shifted according tothe method, the vehicle will benefit from reduced fuel consumption because ofthe small amount of energy required when shifting gears and due to the effec-tively use of the gearbox components when shifting gears.

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 the main 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; Figure 3 schematically illustrates a shifting matrix for a gearbox according to an embodiment; Figure 4 illustrates a flow chart for a method, performed by a control device, forshifting gears in a gearbox according to an embodiment; and Figure 5 schematically illustrates a control device or computer according to an embodiment.

DETAILED DESCRIPTION The method according to the present disclosure, provides for shifting gears ina gearbox, which shifting requires a small amount of energy when gears areshifted in the gearbox. ln addition, the method provides for shifting gears in agearbox, in which gearbox the components in the gearbox are effectively usedwhen shifting gears. When the gearbox is arranged in a vehicle and gears areshifted according to the method, the vehicle will benefit from reduced fuel con-sumption because of the small amount of energy required when shifting gearsand due to the effectively use of the gearbox components when shifting gears.

According to an aspect, the present disclosure relates to a method, performedby a control device, for shifting gears in a gearbox.

The gearbox comprises: 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; a lay shaft connectable to the first gear pair and to the second gear pair, and a third gear pair connectable to the input shaft, themain shaft and the |ay shaft.

The method comprises: connecting the second gear pair to the main shaft;disconnecting the third gear pair from the input shaft and from the main shaft;and connecting the first gear pair to the input shaft and with the |ay shaft.

The third gear pair together with the first gear pair represent gear steps in amain gear group in the gearbox, and wherein the third gear pair together withthe second gear pair represent a second range gear group in the gearbox.

The gearbox may be adapted for a vehicle. The vehicle may be any type ofvehicle. Thus, the vehicle may be a heavy goods vehicle, such as a truck or abus. The gearbox comprises an input shaft, which is adapted to be connectedto a propulsion unit. The propulsion unit may be an internal combustion engineor an electrical machine or a combination thereof. A controllable clutch may bearranged between the propulsion unit and the input shaft of the gearbox, sothat the propulsion unit may be disconnected from the gearbox during certaindriving conditions, such as idle, gear shifting or start-up of the propulsion unit.The main shaft may be connectable to the input shaft by means of a bearing,so that the input shaft and the main shaft may rotate at different speeds in rela-tion 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 |ay shaft. The second gear pair is con-nectable to the main shaft and to the |ay shaft. The third gear pair may be con-nectable to the input shaft or the |ay 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 to the 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 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 lowrange 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, thesecond range gear group is shifted to a high range gear position. ln the highrange 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 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 a vehicle provided with the gearbox. This may also increasethe comfort for passengers in a vehicle provided with the gearbox.

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 for different purposes in the gearbox. Since third gear pair is connectable to theinput shaft and the lay 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 lay 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 lay 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.

The steps of connecting the second gear pair to the main shaft, disconnectingthe third gear pair from the input shaft and from the main shaft, and connectingthe first gear pair to the input shaft and with the lay shaft will shift the gearboxinto a first driving gear.

According to an aspect, disconnecting the third gear pair from the input shaftand from the main shaft comprises disconnecting a third gear wheel (30) of thethird gear pair from the input shaft and from the main shaft, so that the thirdgear wheel is free to rotate in relation to the input shaft and in relation to themain shaft.

When disconnecting the third gear wheel and the input shaft, and thus disen-gaging a gear in the gearbox, the third axially displaceable sleeve is displacedin the axially direction of the input shaft and thus disengaging the splines of thesleeve from the splines of the third gear wheel. Before disconnecting the thirdgear wheel from the input shaft, torque balance between the third gear wheeland the input shaft is generated. When the third axially displaceable sleeve nolonger transfer torque between the third gear wheel and the input shaft, thesleeve may be displaced axially in order to disconnect the third gear wheelfrom the 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, disconnecting the third gear pair from the input shaftand from the main shaft comprises disconnecting the input shaft from the main shaft, so that the input shaft is free to rotate in relation to the main shaft.

A second bearing may be arranged between the input shaft and the mainshaft. The main shaft may be rotatably connected to the input shaft by meansof a bearing, so that the input shaft and the main shaft may rotate at differentspeeds in relation to each other. This is suitable since rotational speed andtorque from the input shaft may be transferred to the lay 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 rotational speed of the input and main shafts may be different. When asecond 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 method comprises the further steps of: disconnect-ing the first gear pair from the input shaft or from the lay shaft, and connecting the third gear pair to the input shaft. 11 The first gear pair may be connectable and disconnectable from the input shaftor from the |ay shaft. When disconnecting the first gear pair from the inputshaft or from the |ay shaft, the first gear pair will not transfer torque betweenthe input shaft and the |ay shaft. lnstead torque will be transferred between theinput shaft and the |ay shaft when connecting the third gear pair to the inputshaft, since the third gear pair is arranged between the input shaft and the |ayshaft. Disconnecting the first gear pair from the input shaft or from the |ayshaft, and connecting the third gear pair to the input shaft will shift the gearbox into a fourth driving gear.

According to an aspect, disconnecting the first gear pair from the input shaft orfrom the |ay shaft comprises disconnecting a first gear wheel of the first gearpair from the |ay shaft, so that the first gear wheel is free to rotate in relation to the input shaft.

The first gear wheel may be connected to and disconnected from the |ay shaftby means of a first axially displaceable sleeve, which is provided with splines.The splines of the sleeve is configured to connect with corresponding splineson the first gear wheel and the |ay shaft when connecting the first gear wheelto the |ay shaft. The first axially displaceable sleeve is configured to transfertorque. Connecting the first gear wheel to the |ay shaft means that a gear inthe gearbox is engaged. Before connecting the first gear wheel to the |ay shaftthe rotational speed of the first gear wheel and the |ay shaft are synchronized.Thereafter the sleeve is axially displaced to engage with the splines of the firstgear wheel. When disconnecting the first gear wheel and the |ay shaft, andthus disengaging a gear in the gearbox, the first axially displaceable sleeve isdisplaced in the axially direction of the |ay shaft and thus disengaging thesplines of the sleeve from the splines of the first gear wheel. Before discon-necting the first gear wheel from the |ay shaft, torque balance between the firstgear wheel and the |ay shaft is generated. When the first axially displaceablesleeve no longer transfer torque between the first gear wheel and the |ay shaft,the sleeve may be displaced axially in order to disconnect the first gear wheel 12 from the Iay shaft. When the first gear wheel is disconnected from the Iay shaft,the first gear wheel is free to rotate in relation to the Iay shaft.

According to an aspect, connecting the third gear pair with the input shaftcomprises connecting a third gear wheel of the third gear pair with the inputshaft.

The third gear wheel is connected to the input shaft by means of a third axia||ydisp|aceab|e sleeve, which is provided with sp|ines. The sp|ines of the sleeveis configured to connect with corresponding sp|ines on the third gear wheeland the input shaft when connecting the third gear wheel to the input shaft.The third axia||y disp|aceab|e sleeve is configured to transfer torque. Connect-ing the third gear wheel to the input shaft means that a gear in the gearbox isengaged. Before connecting the third gear wheel to the input shaft the rota-tional speed of the third gear wheel and the input shaft are synchronized.Thereafter the sleeve is axia||y displaced to engage with the sp|ines of the third gear wheel.

According to an aspect, the method comprises the further steps of: disconnect-ing the third gear pair from the input shaft; disconnecting the second gear pairfrom the main shaft; and connecting the third gear pair to the main shaft.

In 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. In 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. In thehigh range gear position the second gear pair is disconnected from the mainshaft and/or the Iay shaft.

The third gear wheel may be connected to and disconnected from the mainshaft by means of a second axia||y disp|aceab|e sleeve, which is provided withsp|ines. The sp|ines of the sleeve is configured to connect with corresponding 13 splines 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 splines 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 splines of the sleeve from the splines 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.

The steps of disconnecting the third gear pair from the input shaft, disconnect-ing the second gear pair from the main shaft, and connecting the third gearpair to the main shaft will shift the gearbox into a fourth driving gear.

According to an aspect, disconnecting the second gear pair from the mainshaft comprises disconnecting a second gear wheel of the second gear pairfrom the main shaft, so that the second gear wheel is free to rotate in relationto 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 providedwith splines. The splines of the sleeve is configured to connect with corre-sponding splines 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 to 14 the 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 splines 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 splines of the sleeve from the splinesof 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.

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 themain 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 rotational speed and the second gear wheel may rotate with another rotational speed when the second gear wheel is disconnected from the mainshaft. This is possible since the second gear wheel may be driven by the lay shaft via the second gear pair.

According to an aspect, connecting the third gear pair with the main shaftcomprises connecting a third gear wheel of the third gear pair with the mainshaft. 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, thesecond range gear group is shifted to a high range gear position. ln the highrange gear position the gear ratio is 1:1 or an up-shift takes place in the sec- ond range gear group.

The third gear wheel is connected to the main shaft by means of the secondaxially displaceable sleeve, which is provided with sp|ines. The sp|ines of thesleeve is configured to connect with corresponding sp|ines on the third gearwheel and the main shaft when connecting the third gear wheel to the mainshaft. The second axially displaceable sleeve is configured to transfer torque.Connecting the third gear wheel to the main shaft means that a gear in thegearbox is engaged. Before connecting the third gear wheel to the main shaftthe rotational speed of the third gear wheel and the main shaft are synchro-nized. Thereafter the sleeve is axially disp|aced to engage with the sp|ines ofthe third gear wheel.

According to an aspect, the method comprises the further step of: shifting thefirst range gear group from a low range gear position to a high range gear po- sition.

The output shaft may be connectable to the first range gear group. The firstrange gear group may double the available gear steps in the gearbox. Theoutput shaft may transmit torque from the first range gear group in the gearbox 16 to, for example, wheels of the vehicle. ln the high range gear position the gearratio may be 1 :1. Alternatively, in the high range gear position an up-shift takes place in the first range gear group.

According to an aspect, the method comprises the further step of: shifting thefirst range gear group from a low range gear position to a reverse gear posi- tion.

The first range gear group may be a planetary gear, which is shiftable betweena low range gear position, a high range gear position and a reverse gear posi-tion. A planetary gear may be designed with small dimensions and still theplanetary gear may provide a large gear ratio. ln addition, the planetary gearmay have low weight and still provide a large gear ratio. The small dimensionsand low 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.

A first bearing may be arranged between the main shaft and a gearbox hous-ing of the gearbox in a position between the first and second range geargroups. The main shaft is connected to the first and second range geargroups. ln a position between the first and second range gear groups the mainshaft is rotatably arranged in relation to the gearbox housing by means of abearing. This arrangement will provide stability to the main shaft, which willresult in that the main shaft may be designed with small dimensions and lowweight. The first bearing may be a ball bearing.

A second bearing may be arranged between the input shaft and the mainshaft. The main shaft may be rotatably connected to the input shaft by means 17 of a bearing, 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 lay 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 asecond bearing is arranged between the input and main shaft, they may rotatewith different rotationa| speeds in relation to each other. The second bearingmay be a ball bearing.

The second bearing may be arranged radially inside the first bearing. The firstand second bearings may be arranged at the same axial position along theinput and main shafts. The second bearing is arranged radially inside the firstbearing. As a result, bending forces acting on the input shaft should mainly betransferred through the first and second bearings as radially directed forces.Therefore, the first and second bearings may be designed with reduced di-mensions comparing to a situation in which the bending forces from input shaftresults in both radially and axially forces on the bearings.

The input shaft is adapted to extend in one piece from a first end part of theinput shaft, which is configured to be arranged outside a gearbox housing ofthe gearbox to a second end part of the input shaft, which is configured to berotatably connected to the main shaft in an position between the first and sec-ond range gear groups. Such an input shaft extend almost completely throughthe gearbox in one piece. This will result in an input shaft with a reduced diam-eter comparing to a shaft made of several pieces. The stability of the gearboxincreases due to the input shaft made in one piece. Bearings between thegearwheels that are rotatably arranged on the input shaft may be arrangedwith a reduced diameter. This will increase the efficiency of the gearbox.

The present disclosure will now be further illustrated with reference to the ap- pended figures. 18 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 furtherconnected 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 tothe 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 lay shaft 22 by means of a first axially displaceable sleeve 18.A first gear wheel 23 of the first gear pair G1 is connectable to and discon-nectable from the lay shaft 22. A second gear pair G2 connectable to the mainshaft 16 by means of a second axially displaceable sleeve 20. The lay shaft 22is to the second gear pair G2. A third gear pair G3 is connectable to the inputshaft 12 by means of a third axially displaceable sleeve 24 and connected tothe lay shaft 22. The third gear pair G3 and the first gear pair G1 represent amain gear group MG in the gearbox 4. The main gear group MG also compris-es a fourth gear pair G4. The fourth gear pair G4 is connectable to the inputshaft 12 by means of the third displaceable sleeve 24. The fourth gear pair G4is also connected to the lay shaft 22. The third gear pair G3 and the second gear pair G2 represent a second 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 is 19 configured 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. ln addition to the first, third and fourth gear pairs G1, G3, G4 in the main geargroup lVlG also comprises a fifth gear pair G5. The fifth gear pair G5 is con-nected to the input shaft 12 and connectable to the lay shaft 22 by means ofthe 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 rangegear 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 disp|acea-b|e 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- 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 axial displacement of the axially displaceable sleeves 18, 20, 24 are pro-vided with a respective shift fork 42 arranged in connection the individuallysleeves 18, 20, 24. The shift forks 42 are controlled by individually power means 44, such as a pneumatic, hydraulic or electric cylinders.

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 bypower means 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 and 21 disconnectable 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 s|eeve 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 100 is coupled to the gearbox 4, the propulsionunit 6 and to the clutch 14. The control device 100 controls the gear shifting inthe gearbox 4. The control device 100 may be a computer with appropriatesoftware for this purpose. A number of not shown speed sensors in the gear-box 4 and in the propulsion unit 6 may be connected to the control device 100The control device 100 comprise a computer program P, which can includeroutines to control the gearbox 4 of the present disclosure. The program P maybe stored in an executable form or compressed form in a memory l\/I and/or ina read/write memory. A computer program product may be provided, compris-ing a program code stored on a, by a computer readable medium for perform-ing gear shiftings in the gearbox 4, when said program is run on the controldevice 100. Said code may be non-volatile, stored in said computer readable medium.

Fig. 3 schematically illustrates a shifting matrix for a gearbox according to anembodiment. The shifting matrix shows the positions P1 - P9 for the axiallydisplaceable sleeves 18, 20, 24, 54, 55, 58 at the creeper gear and the forwardgears 1 - 12. The respective position P1 - P9 is shown in fig. 2. ln position P1,the first axially displaceable s|eeve 18 connects the fifth gear pair G5 with thelay shaft 22. ln position P2, the first axially displaceable s|eeve 18 connectsthe first gear pair G1 with the lay shaft 22. ln position P3, the third axially dis- 22 placeable sleeve 24 connects the fourth gear pair G4 with the input shaft 12. lnposition P4, the third axially displaceable sleeve 24 connects the third gearpair G3 with the input shaft 12. ln position P5, the second axially displaceablesleeve 20 connects the third gear pair G3 with the main shaft 16. ln positionP6, the second axially displaceable sleeve 20 connects the second gear pairG2 with the main shaft 16. ln position P7, the fifth axially displaceable sleeve54 connects the ring gear wheel 32 with the gearbox housing 27. ln positionP8, the sixth axially displaceable sleeve 56 connects the planet gear wheelcarrier 36 with the output shaft 21. ln position P9, the seventh axially displace-abie sleeve 58 connects the sun gear wheel 34 with the main shaft 16.

Fig. 4 i||ustrates a flow chart for a method, performed by a control device, forshifting gears in a gearbox according to an embodiment. The gearbox com-prises an input shaft 12 adapted to be connected to a propu|sion unit 6; a mainshaft 16 connectable to the input shaft 12; a first range gear group RG1 con-nected to the main shaft 16; an output shaft 21 connectable to the first rangegear group RG1 ; a first gear pair G1 connectable to the input shaft 12; a sec-ond gear pair G2 connectable to the main shaft 16; a lay shaft 22 connectabieto the first gear pair G1 and to the second gear pair G2, and a third gear pairG3 connectabie to the input shaft 12, the main shaft 16 and the lay shaft 22.

The method comprising the steps of:connecting s101 the second gear pair G2to the main shaft 16; disconnecting s102 the third gear pair G3 from the inputshaft 12 and from the main shaft 16; and connecting s103 the first gear pair G1to the input shaft 12 and with the lay shaft 22.

According to an aspect, disconnecting s102 the third gear pair G3 from theinput shaft 12 and from the main shaft 16 comprises disconnecting s102 a thirdgear wheel 30 of the third gear pair G3 from the input shaft 12 and from themain shaft 16, so that the third gear wheel 30 is free to rotate in relation to the input shaft 12 and in relation to the main shaft16. 23 According to a further aspect, disconnecting s102 the third gear pair G3 fromthe input shaft 12 and from the main shaft 16 comprises disconnecting the in-put shaft 12 from the main shaft 16, so that the input shaft 12 is free to rotatein relation to the main shaft 16.

According to a further aspect, the method comprises the further steps of: dis-connecting s104 the first gear pair G1 from the input shaft 12 or from the |ayshaft 22, and connecting s105 the third gear pair G3 to the input shaft 12.

According to a further aspect, disconnecting s104 the first gear pair G1 fromthe input shaft 12 or from the |ay shaft 22 comprises disconnecting s104 a firstgear wheel 23 of the first gear pair G1 from the |ay shaft 22, so that the firstgear wheel 23 is free to rotate in relation to the input shaft 22.

According to a further aspect, connecting s105 the third gear pair G3 with theinput shaft 12 comprises connecting s105 a third gear wheel 30 of the thirdgear pair G3 with the input shaft 12.

According to a further aspect, the method comprises the further steps of: dis-connecting s106 the third gear pair G3 from the input shaft 12; disconnectings107 the second gear pair G2 from the main shaft 16; and connecting s108 thethird gear pair G3 to the main shaft 16.

According to a further aspect, disconnecting s107 the second gear pair G2from the main shaft 16 comprises disconnecting s107 a second gear wheel 46of the second gear pair G2 from the main shaft 16, so that the second gear wheel 46 is free to rotate in relation to the main shaft 16.

According to a further aspect, connecting s108 the third gear pair G3 with themain shaft 16 comprises connecting s108 a third gear wheel 30 of the third gear pair G3 with the main shaft 16. 24 According to a further aspect, the method comprises the further step of: shift-ing s109 the first range gear group RG1 from a low range gear position to ahigh range gear position.

According to a further aspect, the method comprises the further step of: shift-ing s1 10 the first range gear group RG1 from a low range gear position to a reverse gear position.

Fig. 5 schematically i||ustrates a version of a control device 500 or a computeraccording to an embodiment. The control device 100 described with referenceto Fig. 2 may in a version comprise the device 500. The device 500 comprisesa non-volatile memory 520, a data processing unit 510 and a read/writememory 550. The non-volatile memory 520 has a first memory element 530 inwhich a computer programme, e.g. an operating system, is stored for control-ling the function of the device 500. The device 500 further comprises a buscontroller, a serial communication port, l/O means, an A/D converter, a timeand date input and transfer unit, an event counter and an interruption controller(not depicted). The non-volatile memory 520 has also a second memory ele-ment 540.

There is provided a computer programme P which comprises routines for con-trolling shifting of gears in the gearbox 4. The programme P may be stored inan executable form or in a compressed form in a memory 560 and/or in a read/write memory 550.

Where the data processing unit 510 is described as performing a certain func-tion, it means that the data processing unit 510 effects a certain part of theprogramme stored in the memory 560 or a certain part of the programmestored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via adata bus 515. The non-volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 isintended to communicate with the data processing unit 510 via a data bus 511.The read/write memory 550 is adapted to communicating with the data pro-cessing unit 510 via a data bus 514.

When data are received on the data port 599, they are stored temporarily inthe second memory element 540. When input data received have been tempo-rarily stored, the data processing unit 510 is prepared to effect code executionas described above.

Parts of the methods herein described may be effected by the device 500 bymeans of the data processing unit 510, which runs the programme stored inthe memory 560 or the read/write memory 550. When the device 500 runs theprogramme, methods herein described are executed.

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 ski||ed in the art. The embodiments have beenchosen and described in order to best explicate principles and practical appli-cations, and to thereby enable one ski||ed in the art to understand the embod-iments in terms of its various embodiments and with the various modificationsthat are applicable to its intended use. The components and features specifiedabove may, within the framework of the embodiments, be combined betweendifferent embodiments specified.

Claims (13)

26 CLAIIVIS

1. A method, performed by a control device (100), for shifting gears in a gear-box (4), 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); a lay shaft (22) connectable to the first gear pair (G1) and to the second gear pair (G2), and a third gear pair (G3) connectable to the input shaft (12), the main shaft (16) and the lay shaft (22),the method comprising: connecting (s101) the second gear pair (G2) to the main shaft(16): disconnecting (s102) the third gear pair (G3) from the input shaft(12) and from the main shaft (16); and connecting (s103) the first gear pair (G1) to the input shaft (12)and with the Iay shaft (22).

2. The method according to c|aim 1, wherein disconnecting (s102) the thirdgear pair (G3) from the input shaft (12) and from the main shaft (16) comprisesdisconnecting (s102) a third gear wheel (30) of the third gear pair (G3) fromthe input shaft (12) and from the main shaft (16), so that the third gear wheel(30) is free to rotate in relation to the input shaft (12) and in relation to the mainshaft (16). 27

3. The method according to any one of c|aims 1 and 2, wherein disconnecting(s102) the third gear pair (G3) from the input shaft (12) and from the main shaft(16) comprises disconnecting the input shaft (12) from the main shaft (16), sothat the input shaft (12) is free to rotate in relation to the main shaft (16).

4. The method according to any one of the preceding c|aims, wherein themethod comprises the further steps of: disconnecting (s104) the first gear pair (G1) from the input shaft(12) or from the |ay shaft (22), and connecting (s105) the third gear pair (G3) to the input shaft (12).

5. The method according to c|aim 4, wherein disconnecting (s104) the firstgear pair (G1) from the input shaft (12) or from the |ay shaft (22) comprisesdisconnecting (s104) a first gear wheel (23) of the first gear pair (G1) from the|ay shaft (22), so that the first gear wheel (23) is free to rotate in relation to theinput shaft (22).

6. The method according to any one of c|aims 4 and 5, wherein connecting(s105) the third gear pair (G3) with the input shaft (12) comprises connecting(s105) a third gear wheel (30) of the third gear pair (G3) with the input shaft(12).

7. The method according to any one of c|aims 4 - 6, wherein the method com-prises the further steps of: disconnecting (s106) the third gear pair (G3) from the input shaft(12): disconnecting (s107) the second gear pair (G2) from the mainshaft (16); and connecting (s108) the third gear pair (G3) to the main shaft (16). 28

8. The method according to claim 7, wherein disconnecting (s107) the secondgear pair (G2) from the main shaft (16) comprises disconnecting (s107) a sec-ond gear wheel (46) of the second gear pair (G2) from the main shaft (16), sothat the second gear wheel (46) is free to rotate in relation to the main shaft(16).

9. The method according to any one of claims 7 and 8, wherein connecting(s108) the third gear pair (G3) with the main shaft (16) comprises connecting(s108) a third gear wheel (30) of the third gear pair (G3) with the main shaft(16).

10. The method according to any one of claims 7 and 9, wherein the methodcomprises the further step of: shifting (s109) the first range gear group (RG1) from a low rangegear position to a high range gear position.

11. The method according to claim 1, wherein the method comprises the fur-ther step of: shifting (s110) the first range gear group (RG1) from a low rangegear position to a reverse gear position.

12. A computer program (P) comprising instructions which, when the programis executed by a computer (100; 500), cause the computer (100; 500) to carry out the method according to any one of the preceding claims.

13. A computer-readable medium comprising instructions, which when execut-ed by a computer (100; 500), cause the computer (100; 500) to carry out themethod according to any one of claims 1-11.