SE1650361A1

SE1650361A1 - Shift control arrangement with interlock in a vehicle gearbox

Info

Publication number: SE1650361A1
Application number: SE1650361A
Authority: SE
Inventors: Norberg Peer; Arnelöf Per
Original assignee: Scania Cv Ab
Priority date: 2016-03-17
Filing date: 2016-03-17
Publication date: 2017-09-18
Also published as: SE539727C2; WO2017160220A1; BR112018017215A2; DE112017000650T5

Abstract

22 Abstract The invention relates to a shift control arrangement (3) in a gearbox (2), comprising afirst shift rod (68), provided with a first and second end part (72, 82), which first end(72) part is connectable to a first power means (66) and the second end part (82) isconnected to a first shift fork (60); a second shift rod (70), provided with a first andsecond end part (73, 84), which first end part (73) is connectable to a second powermeans (67) and the second end part (84) is connected to a second shift fork (61 ); afirst set of grooves (86) arranged in the first shift rod (68), a second set of grooves(88) arranged in the second shift rod (70); and a first and a second lock pin (75, 79)arranged between the first and second shift rods (68, 70), which first and a secondlock pins (75) together with the first and second set of grooves (86, 88) are arrangedto restrict or allow axial movement of the respective first and second shift rod (68,70). The second set of grooves (88), comprises a first and second groove (94, 95),each extending in an axial direction of the second shift rod (70), so that each of thefirst and second groove (94, 95) is common for two shift gears in the gearbox (2).The invention also relates to a gearbox (2) and to vehicle (1), which comprises sucha gearbox (2). (Pig. sa)

Description

Shift control arrangement in a gearbox BACKGROUND AND PRIOR ART The invention relates to a shift control arrangement in a gearbox for vehicles, a gear-box comprising such a shift control arrangement and a vehicle comprising such a gearbox, according to the appended claims. ln vehicles, and especially for heavier vehicles such as trucks, a range gearbox de-vice is often connected a main gearbox device to double the number of gears. Suchan auxiliary gearbox device usually includes a planetary gear, which has a low gearand a high gear, wherein the shift facilities of the main gearbox device can be dividedinto a low range gear position and a high range gear position. ln low range gear adownshift takes place through the planetary gear, and in the high range gear the gearratio is 1: 1 in the planetary gear.

The range gearbox device is usually provided between the main gearbox device anda propeller shaft coupled to the drive wheels of the vehicle. The main gearbox deviceis accommodated in a main gearbox housing and the range gearbox device is ac-commodated in a range gearbox housing. The range gearbox device comprises aninput shaft coupled to the main gearbox device, an output shaft and between the in-put shaft and the output shaft the planetary gear is disposed. The planetary gearusually comprises three components, which are rotatable arranged relative to eachother namely a sun gear wheel, a planet carrier with planet gear wheels and a ringgear wheel. With knowledge of the number of teeth of the sun gear wheel and thering gear wheel the relative speed of the three components can be determined duringoperation. ln a range gearbox device the sun gear wheel can be rotatable connectedto the input shaft, a number of planet gear wheels which engage said sun gearwheel, which planet gear wheels are rotatable mounted on the planet carrier which is fixedly connected to the output shaft, and the ring gear wheel which surrounds and engages the planet gear wheels. ln a known range gearbox device the low range gear position and high range gearposition are obtained by displacing an axially displaceable sleeve between the lowrange gear position, in which the ring gear is rotationally locked relative to the rangegearbox housing, and high range gear position in which the ring gear wheel is ro-tatable relative to the range gearbox housing and where the ring gear wheel, the planet gear wheels and the sun gear wheel rotate as a common unity.

The axially displaceable coupling sleeve is provided with splines and by controllingthe transmission to synchronous speed between the two components to be con-nected an axial displacement of the coupling sleeve along the two components ismade possible in order to connect them. When the components should be detachedthe transmission is controlled so that torque balance occurs between the componentsso that the coupling sleeve is not transmitting torque. lt then becomes possible tomove the coupling sleeve along the components in order to disengage them fromeach other.

The document US6196944 shows a planetary gear comprising a sun gear, a planetcarrier with planet gears and a ring gear. The sun gear may be connected to the in-put shaft by means of a coupling sleeve in a low range gear position and disengagedfrom the input shaft in a high range gear position. ln the high range gear position theinput shaft is connected to of the planet carrier by means of the same couplingsleeve. The ring gear is firmly connected to a gearbox housing. The known planetary gear is arranged in an auxiliary gearbox, having only two gear positions.

The reverse gear in a transmission in a vehicle is often arranged in the main gear-box, which then comprises a gear which is engaged when the vehicle is to be drivenin the reversed direction. The gear wheel, which is intended for the reverse gear,causes an elongation of the main gearbox device, and an undesired increase inweight of the vehicle. The reverse gear wheel rotates in the opposite direction to theother gears in the main gearbox device, which causes losses. Said gear wheel whichis intended for the reverse gear has a tendency to produce undesirable noise in the transmission, which is a result of an intermediate gear wheel disposed between a lay shaft and a main shaft in the main gearbox device.

Therefore, it is preferable to replace the reverse gear in the main gearbox device bymeans of a reverse gear arranged in the range gearbox device. The reverse geararranged in the range gearbox device is shifted by means a second axially displace-able sleeve. When the range gearbox device is shifted into the reverse gear, thesecond axially displaceable sleeve connects the ring gear wheel with the propellershaft at the same time as the first axially displaceable sleeve connects the planet car-rier with the range gearbox housing.

The document US6196944 shows a gearbox for motor vehicles comprising a plane-tary gear comprising a first and a second sleeve acting on the planet carrier, the ringgear, the gearbox housing and the output shaft. The first and second sleeves are controlled as one connected unit.

The axial displacement of the first and second coupling sleeves are provided with afirst and second shift fork arranged in an outside circumferential groove in the re-spective coupling sleeve. The shift forks are influenced by a first and second powermeans, which may be a pneumatic or hydraulic cylinder. Shift rods connected to thepower means and the shift forks transfer the axial movement from the power meansto the shift forks. When assembling and disassembling the range gearbox device toand from the main gearbox device the shift rods are preferably connected to and dis- connected from the power means. ln order to prevent damage in the range gearbox device due to selecting an impro-priate gear when shifting gears in the range gearbox device the shift control ar-rangement for the range gearbox device is provided with a shift interlock. Such animpropriate selection of gears may be the selection of the low range gear when therange gearbox device is shifted into the reverse gear. ln this case both gear wheels and the coupling sleeves could be damaged.

A known shift interlock for a transmission is disclosed in document US4120212. Theshift interlock comprises a pair of lock pins, which are disposed in lock pin bores ar- ranged in a housing. The lock pins are designed to engage annular grooves in a pairof shift rods, which are restricted to move axially when the lock pin engages the an-nular groove. Thus, an impropriate gear when shifting gears can be avoided. How-ever, the known shift interlock is only appropriate for transmissions in which only oneshift rod is controlled when shifting between a forward and reverse mode.

SUMMARY OF THE INVENTION There is a need to further develop a shift control arrangement in a gearbox in whichan inadvert selection of a forward or reverse mode is prevented. Also, there is a needto further develop a shift control arrangement in a gearbox in which two shift rods arecontrolled when shifting between a forward and reverse mode, and in which an inad- vert selection of a forward or reverse mode is prevented.

The object of the present invention is therefore to develop a shift control arrangementin a gearbox in which an inadvert selection of a forward or reverse mode is pre- vented.

Another object of the present invention is to develop a shift control arrangement in agearbox in which two shift rods are controlled when shifting between a fon/vard andrean/vard mode, and in which an inadvert selection of a fon/vard or reverse mode is prevented.

The herein mentioned objects are achieved by the above-mentioned shift control ar-rangement in a gearbox according to the independent claims.

According to the invention the shift control arrangement in a gearbox comprises afirst shift rod, provided with a first and second end part, which first end part is con-nectable to a first power means and the second end part is connected to a first shiftfork; a second shift rod, provided with a first and second end part, which first end partis connectable to a second power means and the second end part is connected to asecond shift fork; a first set of grooves arranged in the first shift rod, a second set ofgrooves arranged in the second shift rod; and a first and a second lock pin arrangedbetween the first and second shift rods, which first and a second lock pins together with the first and second set of grooves are arranged to restrict or allow axial move-ment of the respective first and second shift rod. The second set of grooves com-prises a first and second groove, each extending in an axial direction of the secondshift rod, so that each of the first and second grooves is common for two shift gearsin the gearbox.

Such a shift control arrangement effectively prevents an inadvert selection of a for-ward or reverse mode in the gearbox. When each of the first and second grooveshas an axial extension, so that the first and second grooves are common for two shiftgears, the gearbox cannot be shifted to the fon/vard or reverse mode in situationswhere the gearbox could be damaged. A situation where the gearbox would be dam-aged is for example when the gearbox is shifted into a low range gear and the re-verse gear mode is selected. Another example is when the gearbox is shifted into thereverse mode and where the forward mode is selected. Such impropriate selectionmay be made by a driver of a vehicle in which the gearbox is arranged or when acomponent that controls the gearbox fails.

According to one embodiment of the invention, the first set of grooves comprises athird, fourth, fifth and sixth groove, each related to a shift gear in the gearbox. Thegrooves in the first shift rod preferably relates to the different possibilities of shiftgears in the gearbox. Their function is to receive the lock pins in different gear shift modes.

According to a further embodiment of the invention, the first groove is arranged tocooperate with the third and fourth grooves by means of the first lock pin and thesecond groove is arranged cooperate with the fifth and sixth grooves by means of thesecond lock pin. When the first lock pin is received in the first groove it will not restrictthe movement of the first shift rod. When the first lock pin is received in the third andfourth grooves it will not restrict the movement of the second shift rod. When the sec-ond lock pin is received in the second groove it will not restrict the movement of thefirst shift rod. When the second lock pin is received in the fifth and sixth grooves it will not restrict the movement of the second shift rod.

According to a further embodiment of the invention, the first groove re|ates to a neu-tral and a reverse shift gear in the gearbox and the second groove re|ates to a neu-tral and a reverse shift gear in the gearbox. When each of the first and secondgrooves has an axial extension, so that the first and second grooves are common fortwo shift gears, the gearbox cannot be shifted to the forward or reverse mode in situations where the gearbox could be damaged.

According to a further embodiment of the invention the third and fourth grooves relateto a low range gear and a high range gear, respective, and in that the fifth and sixthgrooves relate to a reverse gear and a high range gear, respective. When the gear-box is shifted into a low range gear the reverse gear mode may not be selected.Thus, an inadvert selection of a reverse mode is prevented which would otherwisedamage the gearbox. When the gearbox is shifted into the reverse mode the forwardmode may not be selected. Thus, an inadvert selection of a forward mode is pre-vented which would otherwise damage the gearbox.

According to a further embodiment of the invention the first end part of the first shiftrod is connectable to the first power means by means of a first coupling element; andin that the first end part of the second shift rod is connectable to the second powermeans by means of a second coupling element. Such first and second coupling ele-ments make it possible to connect and remove the shifting rods from the power means when assembling and disassembling the gearbox in the vehicle.

According to a further embodiment of the invention the first and a second lock pinsare arranged at a main gearbox housing, which at least partly surrounds the maingearbox device. When arranging the lock pin at the main gearbox housing, the axialextension of a range gearbox device arranged on the main gearbox device can bereduced. The range gearbox device can therefore be designed with a short axial ex-tension which reduces the weight of the range gearbox device. Thus, assembling anddisassembling the gearbox in the vehicle will be easy.

According to a further embodiment of the invention the first and second shift forks arearranged in a range gearbox device, which is connectable to the main gearbox de-vice. Thus, the shift control arrangement is arranged to control the gear shifting in therange gearbox device.

According to a further embodiment of the invention the first set of grooves togetherwith the first and a second lock pins are arranged to prevent the first shift rod to moveaxially and to allow the second shift rod to move axially; and in that the second set ofgrooves together with the first and a second lock pins are arranged to prevent thesecond shift rod to move axially and to allow the first shift rod to move axially. Thegrooves are arranged to receive the first and a second lock pins for different shiftgears and thereby restrict either the first or second shift rod to move axially in orderto prevent an inadvert selection of a forward or reverse shift gear mode which wouldotherwise damage the gearbox.

A reverse gear in the power train is achieved when a first axially movable couplingsleeve is arranged to engage a planet carrier with the range gearbox housing and asecond axially movable coupling sleeve is arranged to engage a ring gear with anoutput shaft. The reverse gear can be easily shifted to by controlling the first andsecond axially displaceable coupling sleeves. However, a malfunction in a controlsystem of the gearbox may unintentional be activating the power means and moveone of the first and second axially displaceable coupling sleeves. Thus, if the gearboxis unintentional shifted into the reverse gear when the vehicle is moving fon/vard itmay cause damage to the gearbox. The shift control arrangement in a gearbox isarranged to avoid such an incident.

Further advantages of the invention appear from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Below is a description of, as examples, preferred embodiments of the invention withreference to the enclosed drawings, in which: Fig. 1 shows schematically a vehicle in a side view with a gearbox having a shift control arrangement according to the invention, Fig. 2 shows schematically a cross section of the gearbox in a low range positionprovided with a shift control arrangement according to the invention, Fig. 3 shows schematically a cross section of the gearbox in a reverse mode pro- vided with a shift control arrangement according to the invention, Fig. 4 shows schematically a cross section of the gearbox in a high range positionprovided with a shift control arrangement according to the invention, Figures 5a - 5f show schematically a shift control arrangement according to the in-vention in different shift gear positions, and Figures 6a - 6b show schematically two different embodiments of a cross section through line l - l of the second shift rod in fig. 5a.

DETAILED DESCRIPTION OF PREFERRED EI\/|BOD||\/IENTS OF THE INVENTION Fig. 1 shows schematically a vehicle 1 in a side view with a gearbox 2 provided witha shift control arrangement 3 according to the invention. The vehicle 1 is also pro-vided with an internal combustion engine 4, a clutch 5, a propeller shaft 10 and drivewheels 8. The combustion engine 4 is coupled to the gearbox 2 via the clutch 5. Thegearbox 2 comprises a main gearbox device 11 and a range gearbox device 6. Themain gearbox device 11 is surrounded by a main gearbox housing 12 and the rangegearbox device 6 is surrounded by a range gearbox housing 13. However, the maingearbox device 11 and the range gearbox device 6 may be surrounded by a commonhousing. The gearbox 2 is connected to the drive wheels 8 of the vehicle 1 via thepropeller shaft 10. lnstead of an internal combustion engine 4 the vehicle may beprovided with an electric engine as part of a powertrain 15 in the vehicle 1.

Fig. 2 shows a schematic sectional view of a gearbox 2 having a shift control ar-rangement 3 according to the invention. The range gearbox device 6 comprises aplanetary gear 14 which has a low and a high gear, so that the shifting capability ofthe gearbox 2 can be divided into a low range gear position and a high range gearposition. ln a first gear position corresponding to the low range gear position a down-shift takes place in the planetary gear 14. ln the high range gear position the gearratio is 1: 1 in the planetary gear 14. Fig. 2 shows the range gearbox device 6 in thefirst gear position, corresponding to the low range gear position.

The gearbox 2 also comprises a split gearbox device 7 and a lay shaft 9. The maingearbox device 11 is provided with a main shaft 26, which is connected to the plane-tary gear 14 of the range gearbox device 6. The planetary gear 14 comprises threemain components which are rotatable arranged in relation to each other, namely asun gear 18, a planet carrier 20 and a ring gear 22. A number of planet gears 24 arerotatable arranged with bearings on the planet carrier 20. With knowledge of thenumber of teeth 32 of sun gear 18 and the ring gear 22, the relative gear ratio of thethree components can be determined. The sun gear 18 is connected to the mainshaft 26 of the main gearbox device 11 and the planet gears 24 engage the sun gear18. The ring gear 22 surrounds and engages the planet gears 24. The main shaft 26is preferably connected to a shaft 38 of the sun gear 18 by means of a splines con-nection 34, which has an axial extent and which allows an axial displacement be-tween the main shaft 26 and the shaft 38 of the sun gear 18 when assembling anddisassembling the range gearbox device 6 to and from the gearbox 2. The input shaft16 is at its end provided with a sleeve 36, which internally cooperates with the cir-cumference of a portion of the shaft 38 of the sun gear 18 by mean of the splinesconnection 34. Thus, the splines connection 34 is preferably designed such that therange gearbox device 6 can be assembled and disassembled in one piece to andfrom the rest of the gearbox 2. Thus, the maintenance costs are reduced, since thetime required for the repair decreases.

A first axially displaceable coupling sleeve 42 is in a first gear position arranged toconnect the range gearbox housing 13 with the ring gear 22 and in a second gearposition arranged to disconnect the range gearbox housing 13 from the ring gear 22.The first axially displaceable coupling sleeve 42 is in the first gear position arrangedto disconnect the shaft 38 of the sun gear 18 from the planet carrier 20. ln the secondposition the first axially displaceable coupling sleeve 42 connects the shaft 38 of thesun gear 18 with the planet carrier 20.

A second axially displaceable coupling sleeve 43 is in the first and second gear posi-tions arranged to interconnect the planet carrier 20 with the output shaft 28. The sec-ond axially displaceable coupling sleeve 43 is in a third gear position arranged to couple the ring gear 22 with an output shaft 28 of the gearbox 2. The output shaft 28 is coupled to the propeller shaft 10 of the vehicle 1. ln the third gear position, corre-sponding to a reverse gear, the first axially displaceable coupling sleeve 42 is ar-ranged to disconnect the shaft 38 of the sun gear 18 from the planet carrier 20 andinstead is arranged to interconnect the planet carrier 20 with the range gearbox hous-ing 13.

The first axially displaceable coupling sleeve 42 is on an inner and outer surface pro-vided with first splines 50, which on the inner surface is arranged to interact with thecorresponding first splines 50 arranged on the ring gear 22. The first splines 50 onthe outer surface is arranged to interact on the inner periphery of a projection 52which is fixedly connected to the range gearbox housing 13. The first splines 50 onthe inner surface of the first axially displaceable coupling sleeve 42 are also arrangedto cooperate with corresponding first splines 50 arranged on the input shaft 16. Cor-responding first splines 50 disposed on the input shaft 16 are made on the peripheryof a first sprocket 46 which is mounted on the shaft 38 of the sun gear 18. However,it is also possible to arrange the first sprocket 46 on the input shaft 16 instead of onthe shaft 38 of the sun gear 18. Thus, the first sprocket 46 may be arranged on eitherside of the splines connection 34. The first splines 50 on the inner surface of the firstaxially displaceable coupling sleeve 42 are also arranged to cooperate with corre-sponding first splines 50 arranged on the planet carrier 20. Corresponding firstsplines 50 disposed on the planet carrier 20 are made on the periphery of a secondsprocket 44 which is mounted on the planet carrier 20.

The second axially displaceable coupling sleeve 43 is on an inner surface providedwith second splines 51 which are arranged to cooperate with corresponding secondsplines 51 arranged on the ring gear 22, the planet carrier 20 and the output shaft 28.The corresponding second splines 51 arranged on the planet carrier 20 are formedon the periphery of a third sprocket 49 which is mounted on the planet carrier 20. Thecorresponding second splines 51 provided on the output shaft 28 are formed on theperiphery of a fourth sprocket 53 which is mounted on the output shaft 28.

An axial stop 54 arranged on the planet carrier 20 is adapted to abut against the ringgear 22, which axial stop 54 prevents the ring gear 22 to be moved axially. The axialstop 54 may consist of a disc-shaped plate, which by a first thrust bearing 56 is 11 mounted on the planet carrier 20. The axial stop 54 is rotatable relative to the planetcarrier 20 and the input shaft 16, and follows the rotation of the ring gear 22. The ax-ial stop 54 fixates the ring gear 22 axially, and leads to that the axial bearing of theinput shaft 16 in the gearbox 2 is subjected to less stress when the gears 18, 22, 24are provided with helical teeth. However, instead of, or in combination with the axialstop 54 a pair of thrust bearings 55 may be arranged on both distal surfaces of thering gear 22. Thus, the thrust bearings 55 are arranged between the ring gear andthe planet carrier 20. A second thrust bearing 57 may be disposed between the shaft38 of the sun gear 18 and the planet carrier 20 to accommodate axial forces gener- ated in the sun gear 18.

The low gear in the gearbox 2 is obtained by displacing the first coupling sleeve 42axially, so that the ring gear 22 is connected to the range gearbox housing 13.

The range gearbox device 6 according to the invention functions as follows whenshifting from the first to the second gear position, that is, from the low range gear po-sition to the high range gear position. ln Fig. 2, the range gearbox device 6 is shiftedinto the low range gear position, which means that the first coupling sleeve 42 hasbeen shifted to a position to connect the ring gear 22 with the range gearbox housing13. Thus, when the range gearbox device 6 is in the low range gear position, adownshift takes place through the planetary gear 14. The shifting operation from thelow range gear position to the high range gear position is made by disconnecting thefirst ring gear 22 from the range gearbox housing 13 by means of the first couplingsleeve 42 when the torque transmission between the ring gear 22 and range gearboxhousing 13 ends, which is accomplished by disconnecting the internal combustionengine 4 from the main gearbox device 11 through disconnection of the clutch 5 anddisconnecting the output shaft from the planet gear carrier by displacing the secondaxially displaceable coupling sleeve 43 to a neutral position. A neutral position maybe achieved by displacing the second coupling sleeve 43 to a position where thesecond coupling sleeve 43 only is connected to the fourth sprocket 53 which ismounted on the output shaft 28. When the first coupling sleeve 42 no longer trans-mits any torque the axial displacement of the first coupling sleeve 42 is possible. lnthe high range gear position the first coupling sleeve 42 is displaced to a positionwhere the first coupling sleeve 42 connects the planet carrier 20 to the first sprocket 12 46. When the range gearbox device 6 has been shifted into the high range gear posi-tion the clutch 5 is engaged and the planet carrier 20 is synchronized to the speed ofthe output shaft 28 before the second coupling s|eeve 43 is displaced to a position forconnecting the planet carrier 20 to the output shaft 28. Thus, the range gearbox de-vice 6 operates in the high range gear position. Fig. 3 shows the range gearbox de- vice 6 in the second gear position, corresponding to the high range gear position. ln order to shift gear to the low range gear position, the first coupling s|eeve 42 isshifted by the first shift fork 60 in the right direction in Fig. 3 for re|easing the planetcarrier 20 from first sprocket 46 and thus from the input shaft 16. This is made possi-ble when the torque transmission between the input shaft 16 and planet carrier 20ends, which is accomplished by disconnecting the internal combustion engine 4 fromthe main gearbox device 11 by means of the clutch 5 and disconnect the planetarygear 14 from the output shaft 28 by means of axially displace the second couplings|eeve 43 to a neutral position. When the first coupling s|eeve 42 no longer transmitsany torque and the planetary gear 14 has been brought to a standstill position theaxial displacement of the first coupling s|eeve 42 is possible. The first coupling s|eeve42 is then shifted by the first shift fork 60 in the direction of the range gearbox hous-ing 13 to thereby connect the ring gear 22 with the range gearbox housing 13. Whenthe ring gear 22 is stationary, the first coupling s|eeve 42 is displaced axially and in-terferes with the first splines 50 on the ring gear 22 and the range gearbox housing13. Thus, in the low range gear position a downshift occurs through the range gear-box device 6. When the range gearbox device 6 has been shifted into the low rangegear position the clutch 5 is engaged and the planet carrier 20 is synchronized to thespeed of the output shaft 28 before the second coupling s|eeve 43 is displaced to aposition for connecting the planet carrier 20 to the output shaft 28.

Fig. 4 shows the range gearbox device 6 in the third gear position, corresponding tothe reverse gear position mode. The second axially displaceable s|eeve 43 is in thethird gear position, i.e. in the reverse gear position arranged to connect the ring gear22 with output shaft 28. Thus, the second coupling s|eeve 43 is shifted by the secondshift fork 61, so that the ring gear 22 is connected to the output shaft 28. The firstcoupling s|eeve 42 is shifted by the first shift fork 60 to couple the planet carrier 20with the range gearbox housing 13. The displacement of the respective coupling 13 sleeve 42, 43 is performed when the input and the output shaft 16, 28 are stationary,which corresponds to a stationary operating state of the vehicle 1, or when the vehi-cle 1, travels backwards and the planetary gear 14 is disconnected from the outputshaft 28 by means of the second coupling sleeve 43. The second coupling sleeve 43may thereafter be displaced to connect the output shaft 28 with the second couplingsleeve 43 when the speed of the planetary gear 14 is synchronized to the speed ofthe output shaft 28 by means of the engine 4.. ln order to provide a stationary posi-tion of the input shaft 16 the clutch 5 of the vehicle 1 is transferred to a disconnectedmode. When the range gearbox device 6 is operated in the third gear position, torqueis transmitted from the input shaft 16 to the sun gear 18 and further to the planetgears 24 which transmits the torque to the ring gear 22 and further to the output shaft28 via the second coupling sleeve 43. The planet carrier 20 is stationary as the firstcoupling sleeve 42 connects the planet carrier 20 with the range gearbox housing 13.

When the first coupling sleeve 42 is displaced from the right to left in fig. 2 the firstcoupling sleeve 42 will shift the range gearbox device 6 from the low range gear posi-tion to the reverse gear positon and further to the high range gear position.

The shift control arrangement 3 according to the invention comprises first and secondpower means 66, 67 which are provided for the axial displacement of the first andsecond coupling sleeves 42, 43. The first power means 66 is connected to a first shiftfork 60, which is arranged in an outside circumferential groove 62 in the first couplingsleeve 42. The first power means 66 is connected to the first shift fork 60 by meansof a first shift rod 68, which may be detachable from the first power means 66 bymeans of a first coupling element 69. The second power means 67 is connected to asecond shift fork 61, which is arranged in an outside circumferential groove 62 in thesecond coupling sleeve 43. The second power means 67 is connected to the secondshift fork 61 by means of a second shift rod 70, which may be detachable from thesecond power means 67 by means of a second coupling element 71. The first andsecond power means 66, 67 may be a pneumatic or hydraulic cylinder, or en electricactuator. The shift rods 68, 70 connected to the power means 66, 67 transfers theaxial movement from the power means 66, 67 to the shift forks 60, 61. When assem-bling and disassembling the range gearbox device 6 to and from the main gearboxdevice 11 the shift rods 68, 70 are connected to and disconnected from the power 14 means 66, 67. The shift rods 68, 70 and power means 66, 67 are schematicallyshown on top of the main gearbox housing 12 and on the range gearbox housing 13in Figures 2 - 4.

A first end part 72 of the first shift rod 68 is connectable to the first power means 66by means of the first coupling element 69. A first end part 73 of the second shift rod70 is connectable to the second power means 67 by means of the second couplingelement 71. Such first and second coupling elements 69, 71 make it possible to con-nect and remove the shifting rods 68, 70 from the power means 66, 67 when assem-bling and disassembling the gearbox 2 in the vehicle 1. ln order to prevent damage in the range gearbox device 6 due to selecting an impro-priate gear when shifting gears in the range gearbox device 6 the shift control ar-rangement 3 according to the invention is provided with a shift interlock 74. Such animpropriate selection of gears may be the selection of the low range gear when therange gearbox device 6 is shifted into the reverse gear. A malfunction in a controlsystem of the gearbox 2 may unintentional be activating the power means 66, 67 andmove one of the first and second axially displaceable coupling sleeves 42, 43. As aresult the gear wheels in the range gearbox device 6 and also the coupling sleeves42, 43 could be damaged.

The shift interlock 74 comprises a first and a second lock pin 75, 79 which are pref-erably arranged at the main gearbox housing 12, which at least partly surrounds themain gearbox device 11. When arranging the lock pins 75, 79 at the main gearboxhousing 12, the axial extension of a range gearbox device 6 arranged on the maingearbox device 11 can be reduced. The range gearbox device 6 can therefore bedesigned with a short axial extension which reduces the weight of the range gearboxdevice 6. Thus, assembling and disassembling the range gearbox device 6 in thevehicle 1 will be easy.

Figures 5a - 5f show schematically a shift control arrangement 3 according to theinvention in different shift gear positions.

The first shift rod 68 is provided with a first and second end part 72, 82, which sec-ond end part 82 is connected to the first shift fork 60. The second shift rod 70 is pro-vided with a first and second end part 73, 84, which second end part 84 is connected to the second shift fork 61. A first set of grooves 86 is arranged in the first shift rod 68and a second set of grooves 88 is arranged in the second shift rod 70. The first andsecond lock pins 75, 79 are arranged between the first and second shift rods 68, 70.The second set of grooves 88 comprises a first and second groove 94, 95, each ex-tending in an axia| direction of the second shift rod 70, so that each of the first andsecond grooves 94, 95 is common for two shift gears in the gearbox 2. The first set ofgrooves 86 comprises a third, fourth, fifth and sixth groove 96, 97, 98, 99, each re-lated to a shift gear in the gearbox 2. The first groove 94 is arranged to cooperatewith the third and fourth grooves 96, 97 by means of the first lock pin 75 and the sec-ond groove 95 is arranged to cooperate with the fifth and sixth grooves 98, 99 bymeans of the second lock pin 79. The first groove 94 relates to a neutral and a re-verse shift gear in the gearbox 2 and the second groove 95 relates to a neutral and aforward shift gear in the gearbox 2. The third and fourth grooves 96, 97 relate to alow range gear and a high range gear, respective, and the fifth and sixth grooves 98,99 relate to a reverse gear and a high range gear, respective. The first and secondshift rod 68, 70 each has a central axis 77, 76, respective. The first and second shiftrod 68, 70 each is arranged in a guide bore 90 in the main gearbox housing 12. Thefirst and second lock pin 75, 79 each is arranged in a guide hole 92 in the main gear-box housing 12. However, the first and second shift rods 68, 70 and first and secondlock pins 75, 79 may alternatively be arranged in guide bores and guide holes in therange gearbox housing 13.

Fig. 5a shows schematically a shift control arrangement 3 according to the inventionin a neutral position, and which is prepared to shift the range gearbox device 6 into a low range position.

A second end part 82 of the first shift rod 68 is connected to the first shift fork 60 anda second end part 84 of the second shift rod 70, is connected to the second shift fork61. A first set of grooves 86 is arranged in the first shift rod 68 and a second set ofgrooves 88 is arranged in the second shift rod 70, and the first and second lock pins75, 79 are arranged between the first and second shift rod 68, 70, which lock pins 75,79 together with the first set of grooves 86 and the second set of grooves 88 are ar-ranged to restrict or allow axia| movement of the respective first and second shift rod68, 70. 16 Preferably, the first and second lock pins 75, 79 has a pointed shape in both ends,which will make it possible for the shift rods 68, 70 to move the lock pins 75, 79 axi-ally in the main gearbox housing 12 when shifting gears in the gearbox 2. The firstset of grooves 86 together with the lock pins 75, 79 are arranged to prevent the firstshift rod 68 to move axially and to allow the second shift rod 70 to move axially. Thesecond set of grooves 88 together with the lock pins 75, 79 are arranged to preventthe second shift rod 70 to move axially and to allow the first shift rod 68 to move axi-ally. When the lock pins 75, 79 are arranged within a groove 96, 97, 98, 99 in the firstset of grooves 86, the second shift rod 70 is allowed to move axially and the first shiftrod 68 is restricted to move. When the lock pins 75, 79 are arranged within a groove94, 95 in the second set of grooves 88, the first shift rod 68 is allowed to move axiallyand the second shift rod 70 is restricted to move. ln fig. 5a the second shift rod 70 has been moved to a neutral position and the firstlock pin 75 is free to move into the first groove 88 of the second shift rod 70 when thesecond shift rod 70 is moved into the neutral position. The first shift rod 68 has beenmoved into the low range position. When the first shift rod 68 is moved into the lowrange position the third groove in the first shift rod 68 is positioned in line with the firstlock pin 75. ln order to move the second shift rod 70 to the forward position mode thesecond shift rod 70 will move the first lock pin 75 axially and into the third groove inthe first shift rod 68. The second lock pin 79 is prevented to move axially because thesecond lock pin 79 is not aligned with a groove in the first shift rod 68. However,since the second groove in the second shift rod 70 is extended in the axial directionof the second shift rod 70, the second shift rod 70 is free to move into the forwardposition mode. ln fig. 5b the range gear box is shifted into the low range position inthe fon/vard position mode. lt is evident from fig. 5a that it is not possible to move the second shift rod 70 to thecritical reverse position. The second shift rod 70 cannot push the second lock pin 79in the axial direction when trying to move the second shift rod 70 in the left directionin fig. 5a. Therefore, the second groove 95 together with the second lock pin 79 pre-vents the second shift rod 70 to the critical reverse position. This is also evident fromfig. 2. lf the second coupling sleeve 43 would be axially displaced into the reverseposition, in which the second coupling sleeve 43 connects the ring gear wheel 22 17 with the output shaft 28, the output shaft 28 would be locked to a standstill position,because the ring gear wheel 22 is locked to the range gearbox housing 13 by meansof the first coupling s|eeve 42. This would probably damage the gearbox 2 or other components in the powertrain 15.

Fig. 5c shows schematically a shift control arrangement 3 according to the inventionin a neutral position, and which is prepared to shift the range gearbox device 6 into a reverse position.

The first lock pin 75 is restricted to move axially but the second lock pin 79 is allowedto move axially due to the fifth groove 98 in the first shift rod 68. Therefore it is possi-ble to move the second shift rod 70 since the first groove 94 in the second shift rod70 is extended in the axial direction of the second shift rod 70 and also that it is pos-sible to displace the second lock pin 79 into the fifth grove 98 and allow the secondshift rod 70 to move axially. ln fig. 5d the range gear box device 6 is shifted into the reverse position in the forward position mode. lt is evident from fig. 5c that it is not possible to move the second shift rod 70 to thecritical forward position. The second shift rod 70 cannot push the first lock pin 75 inthe axial direction when trying to move the second shift rod 70 in the right direction infig. 5c. Therefore, the first groove 94 together with the first lock pin 75 prevents thesecond shift rod 70 to the critical forward position. This is also evident from fig. 3. lfthe second coupling s|eeve 43 would be axially displaced into the forward position, inwhich the second coupling s|eeve 43 connects the planet wheel carrier 20 with theoutput shaft 28, the output shaft 28 would be locked to a standstill position, becausethe planet wheel carrier 20 is locked to the range gearbox housing 13 by means ofthe first coupling s|eeve 42. This would probably damage the gearbox 2 or other components in the powertrain 15.

Fig. 5e shows schematically a shift control arrangement 3 according to the inventionin a neutral position, and which is prepared to shift the range gearbox device 6 into ahigh range position. ln the high range position both forward and reverse modes areoptional because neither the fon/vard mode nor the reverse mode is critical for the gearbox 2 when the range gearbox device 6 is shifted into the high range mode. 18 lt is evident from fig. 5e that it is possible to move the second shift rod 70 to the for-ward position as well as the reverse position. The second shift rod 70 is able pushthe first lock pin 75 in the axia| direction when trying to move the second shift rod 70in the right direction in fig. 5e and thus shift the gearbox 2 into the forward mode.Also, the second shift rod 70 is able push the second lock pin 79 in the axia| directionwhen trying to move the second shift rod 70 in the left direction in fig. 5e and thusshift the gearbox 2 into the reverse mode. Therefore, the first groove together withthe first lock pin 75 prevents the second shift rod 70 to the critical forward position.This is also evident from fig. 4. The second coupling sleeve 43 can be axially dis-placed into the forward position and into the reverse position without damage thegearbox 2 or other components in the powertrain 15. The reason for this is that thefirst coupling sleeve 42 is not connected to the range gearbox housing 13. ln fig. 5fthe second shift rod 70 has been moved to the forward position mode.

Figures 6a - 6b show schematically two different embodiments of a cross sectionthrough line l - l of the second shift rod 70 in fig. 5a. According to the embodiment ofthe invention shown in fig. 6a, the second groove 95 of the second shift rod 70 is es-sentially flat and the overall cross section of the second shift rod 70 is essentially cir-cular. This makes it possible to move the second shift rod 70 axially when the secondlock pin 79 is received in the second groove 95. A cross section through the first groove 94 of the second shift rod 70 shows similar characteristics.

According to the embodiment shown in fig. 6b the second groove 95 of the secondshift rod 70 is essentially flat and the overall cross section of the second shift rod 70is essentially square. This makes it possible to move the second shift rod 70 axiallywhen the second lock pin 79 is received in the second groove 95. A cross sectionthrough the first groove 94 of the second shift rod 70 shows similar characteristicsaccording to this embodiment. However, the second shift rod 70 may also have an- other shaped cross section.

Also, the first shift rod 68 may have a cross section provided with a shape that issimilar to the shape of the second shift rod 70. 19 The components and features specified above may within the framework of the in- vention be combined between the different embodiments specified.

Claims

1. A shift control arrangement in a gearbox (2), comprising a first shift rod (68), pro-vided with a first and second end part (72, 82), which first end (72) part is connect-able to a first power means (66) and the second end part (82) is connected to a firstshift fork (60); a second shift rod (70), provided with a first and second end part (73,84), which first end part (73) is connectable to a second power means (67) and thesecond end part (84) is connected to a second shift fork (61 ); a first set of grooves(86) arranged in the first shift rod (68), a second set of grooves (88) arranged in thesecond shift rod (70); and a first and a second lock pin (75, 79) arranged between thefirst and second shift rods (68, 70), which first and a second lock pins (75) togetherwith the first and second set of grooves (86, 88) are arranged to restrict or allow axialmovement of the respective first and second shift rod (68, 70), characterized in thatthe second set of grooves (88), comprises a first and second groove (94, 95), eachextending in an axial direction of the second shift rod (70), so that each of the first and second groove (94, 95) is common for two shift gears in the gearbox (2).

2. A shift control arrangement according to claim 1, characterized in that the first setof grooves (86) comprises a third, fourth, fifth and sixth groove (96, 97 ,98 99), each related to a shift gear in the gearbox (2).

3. A shift control arrangement according to claims 1 and 2, characterized in that thefirst groove (94) is arranged to cooperate with the third and fourth grooves (96, 97) bymeans of the first lock pin (75) and the second groove (95) is arranged to cooperatewith the fifth and sixth grooves (98, 99) by means of the second lock pin (79).

4. A shift control arrangement according to claims 2 or 3, characterized in that thefirst groove (94) relates to a neutral and a reverse shift gear in the gearbox (2) andthe second groove (95) relates to a neutral and a forward shift gear in the gearbox (2)-

5. A shift control arrangement according to any of the preceding claims, character-ized in that the third and fourth grooves (96, 97) relate to a low range gear and ahigh range gear, respective, and in that the fifth and sixth grooves (98, 99) relate to a reverse gear and a high range gear, respective. 21

6. A shift control arrangement according to any of the preceding claims, character-ized in that the first end part (72) of the first shift rod (68) is connectable to the firstpower means (66) by means of a first coupling element (69); and in that the first endpart (73) of the second shift rod (70) is connectable to the second power means (67)by means of a second coupling element (71).

7. A shift control arrangement according to any of the preceding claims, character-ized in that the first and a second lock pins (75, 79) are arranged at a main gearboxhousing (12), which at least partly surrounds a main gearbox device (11).

8. A shift control arrangement according to claim 7, characterized in that the firstand second shift forks (60, 61) are arranged in a range gearbox device (6), which is connectable to the main gearbox device (11).

9. A shift control arrangement according to any of the preceding claims, character-ized in that the first set of grooves (86) together with the first and a second lock pins(75, 79) are arranged to prevent the first shift rod (68) to move axially and to allowthe second shift rod (70) to move axially; and in that the second set of grooves (88)together with the first and a second lock pins (75, 79) are arranged to prevent thesecond shift rod (70) to move axially and to allow the first shift rod (68) to move axi- ally.

10. A gearbox (2), characterized in that the gearbox (2) comprises a shift control ar- rangement (3) according to any of the claims 1-9.

11. A vehicle (1 ), characterized in that the vehicle (1) comprises a gearbox (2) ac-cording to claim 10.