WO2016028207A1

WO2016028207A1 - Transmission for vehicle, vehicle comprising such a transmission and method to control a transmission

Info

Publication number: WO2016028207A1
Application number: PCT/SE2015/050878
Authority: WO
Inventors: Dieter Slapak; Tomas Selling
Original assignee: Scania Cv Ab
Priority date: 2014-08-21
Filing date: 2015-08-19
Publication date: 2016-02-25
Also published as: DE112015003341T5; SE1450970A1

Abstract

The invention relates to a transmission (3) for vehicles (1), comprising a driving motor (4), a main gearbox (6), an auxiliary gearbox (2) and a coupling device (5), arranged between the driving motor (4) and the main gearbox (6), which main gearbox (6) comprises an input shaft (7) connected to the coupling device (5), a countershaft (9) and a main shaft (26), which countershaft (9) is connected with the input shaft (7) and the main shaft (26) via a split gear (11) and a main gear (13), respectively, and which auxiliary gearbox (2) comprises a planetary gear (14) with a ring gear (22), a sun wheel (18) and a planetary wheel carrier (20), on which at least one planetary wheel (24) is rotatably mounted, which ring gear (22) and sun wheel (18) through (32) engage with the at least one planetary wheel (24), wherein the planetary gear (14) is connected with the main shaft (26) of the main gearbox (6), and wherein a first braking device (54) is arranged at the countershaft (9), in order to decelerate the countershaft (9) at shifting in the transmission (3), A second braking device (56) is arranged at the input shaft (7), in order to decelerate the input shaft (7) at shifting in the transmission (3). The invention also relates to a vehicle (1), which comprises such a transmission (3). The invention relates to a method to control such a transmission (3).

Description

Transmission for vehicle, vehicle comprising such a transmission and method to control a transmission

BACKGROUND OF THE INVENTION AND PRIOR ART

The present invention relates to a transmission for vehicles according to the preamble of claim 1. The invention also relates to a vehicle, which comprises such a transmission, according to the preamble of claim 7. The invention also relates to a method to control a transmission according to the preamble of claim 8.

In vehicles, and in particular heavy goods vehicles, such as trucks, an auxiliary gearbox, also called a range gearbox, is often connected to the main gearbox with the objective of doubling the number of potential gearings. Such an additional gearbox usually comprises a planetary gear having a low and a high gear, with which the gear pos- sibilities of the main gearbox may be divided into a low range position and a high range position. In the low range position, a gear reduction occurs through the planetary gear, and in the high range position the gear ratio is 1 : 1 in the planetary gear.

The range gearbox is arranged between the main gearbox and a propeller shaft con- nected to the driving wheels of the vehicle. The range gearbox is housed in a gearbox house and comprises an input shaft connected to the main gearbox, an output shaft and a planetary gearbox arranged between the input shaft and the output shaft. The planetary gearbox usually comprises three components, which are rotatably arranged in relation to each other, namely a sun wheel, a planetary wheel carrier and a ring gear. With knowledge about the number of teeth in the sun wheel and the ring gear, the mutual rotational speeds of the three components may be determined during operation. In a range gearbox, the sun wheel may be connected in a twist-fast manner with the input shaft, a number of planetary wheels that engage in said sun wheel and which planetary wheels are mounted in a rotatable manner on the planetary wheel carrier, which is twist-fast connected with the output shaft, and with an axially shiftable ring gear, which envelops and engages with the planetary wheels. The teeth of the sun wheel, the planetary wheels and the ring gear may be oblique, i.e. they have an angle in relation to the rotational axis common to the sun wheel, the planetary wheel carrier and the ring gear. Alternatively, the sun wheel, the planetary wheels and the ring gear may be fitted with straight cut teeth, i.e. they are substantially parallel with the rotational axis common to the sun wheel, the planetary wheel carrier and the ring gear.

The gearbox's low and high gears, respectively, are achieved by axial sliding of the ring gear between the low range position, in which the ring gear is rotation locked in relation to the gearbox house, and the high range position, in which the ring gear is rotatable in relation to the gearbox house. Such a prior art range gearbox comprises two coupling rings arranged on each side of the ring gear, one high coupling ring and one low coupling ring, respectively, and two synchronisation rings, which are arranged on the respective sides of the ring gear. The synchronisation rings are adapted to achieve synchronous gear shifting. The ring gear's freedom of movement in an axial direction is limited by the geometrical design of the ring gear and the coupling ring.

The document WOO 155620 shows a synchronisation device at a planetary gear, wherein the planetary gear comprises a sun wheel, a planetary wheel carrier and a ring gear. The sun wheel is connected in a twist-fast manner with the input shaft, and a number of planetary wheels engage with the sun wheel, which planetary wheels are rotatably mounted on a planetary wheel carrier, which is connected in a twist-fast manner with an output shaft. An axially shiftable ring gear envelops and engages with the planetary wheels. The low and high gears of the gearbox are obtained by the ring gear being shifted axially between the low range position and the high range position. These synchronisation devices are, however, subjected to wear and result in considerable costs of repair. If the range gearbox transfers large torques, the synchronisation devices will have considerable dimensions, entailing increased weight and increased space requirement. When the high range position is connected, the torque will be transferred from the sun wheel to the planetary wheels, entailing that facets may form on the cog flanks of the sun wheel, which creates noise in the gearbox and accelerates wear of the planetary gear's cogwheels. There are also range gearboxes, in which the synchronisation devices are replaced with splined coupling sleeves. By controlling the transmission in such a way that a synchronous rotational speed arises between the two components that are to be connected, an axial shift of the coupling sleeve is facilitated along the two components, with the ob- jective of connecting and interconnecting these. When the components are to be disconnected from each other, the transmission is controlled in such a way that torque balance arises between the components, meaning that the coupling sleeve does not transfer any torque. It then becomes possible to displace the coupling sleeve along the components with the objective of disconnecting them from each other.

Torque balance relates to a state where a torque acts on an internal ring gear arranged in the planetary gear, representing the product of the torque acting on the planetary wheel carrier of the planetary gear and the gear ratio of the planetary gear, while simultaneously a torque acts on the planetary gear's sun wheel, representing the product of the torque acting on the planetary wheel carrier and (1- the planetary gear's gear ratio). In the event two of the planetary gear's component parts, i.e. the sun wheel, the internal ring gear or planetary wheel carrier, are connected with a clutch device, this clutch device does not transfer any torque between the planetary gear's parts when torque balance prevails. Accordingly, the clutch device may easily be shifted and the planetary gear's component parts may be disconnected.

Document US2009/0095101, Al shows a transmission comprising a main gearbox and a range gearbox. A shiftable sleeve arranged to connect the range gearbox into a low range position or a high range position. The main gearbox comprises an input shaft and a main shaft, on which cogwheels may be connected and disconnected. One or two countershafts may be arranged in the main gearbox, one of which countershafts may be equipped with a braking device.

SUMMARY OF THE INVENTION

Despite prior art solutions, there is a need to further develop a method to control a transmission, where the shift times are short, where the reliability and operational se- curity of the transmission is high, and where all component parts of the transmission are used efficiently. There is also a need to further develop a transmission, with small dimensions in relation to potential torque transmission and a transmission which reduces the fuel consumption in a vehicle comprising the transmission.

The objective of the present invention is to provide a transmission that has small dimensions in relation to possible torque transmission. Another objective of the invention is to provide a transmission that reduces the fuel consumption in a vehicle comprising the transmission.

Another objective of the present invention is to provide a gearbox that requires low energy at shifting.

Another objective of the invention is to provide a gearbox that has a low noise level.

Another objective of the invention is to provide a method to control a transmission, entailing short shifting times.

Another objective of the invention is to provide a method to control a transmission, which entails high reliability and operational security of the transmission.

Another objective of the invention is to provide a method to control a transmission, which uses all component parts in the transmission efficiently.

These objectives are achieved with a transmission for vehicles of the type specified at the beginning, which is characterised by the features specified in claim 1. These objectives are further achieved with a vehicle, which comprises such a transmission, of the type mentioned above, which is characterised by the features specified in claim 7. The above objectives are achieved also with a method to control a transmission of the type specified at the beginning, which is characterised by the features specified in claim 8. Since the second braking device is arranged at the input shaft in order to reduce the rotational speed of the input shaft at shifting in the transmission, a synchronous rotational speed or torque balance may be achieved in the auxiliary gearbox with the ob- jective of changing a gear position.

Since the first axially shiftable coupling sleeve in the second gear position transmits torque from the input shaft to the planetary wheel carrier, and further to the output shaft, and since the second axially shiftable coupling sleeve in the first gear position locks the ring gear with the gearbox house, so that torque is transmitted from the input shaft via the ring gear and the planetary wheel carrier to the output shaft, an efficient transmission with a high efficiency and low losses is obtained. The component parts of the transmission will have a reduced need for lubrication, while facet damage in the cogwheel flanks is minimised.

The axial stroke of each respective coupling sleeve becomes shorter compared to the stroke of the ring gear in a traditional auxiliary gearbox, which entails that shifting between different gear positions is quick. The first and the second coupling sleeve may each be designed with a limited thickness, which means that the mass of each respective coupling sleeve is low. The low mass of each coupling sleeve entails that shifting between different gear positions is quick. According to one embodiment of the invention, the input shaft is connected with the sun wheel, and the planetary wheel carrier is connected with an output shaft in the main gearbox. Thus, the auxiliary gearbox has a simple construction, with few components. According to one embodiment of the invention, the first axially shiftable coupling sleeve is equipped with first splines on an inner surface, which splines are arranged to interact with corresponding first splines, arranged on the input shaft and the planetary wheel carrier. A simple and effective connection and disconnection of the input shaft and the planetary wheel carrier is thus obtained.

According to one embodiment of the invention, the second axially shiftable coupling sleeve is equipped with second splines on an inner surface, which splines are arranged to interact with corresponding second splines, arranged on the ring gear and on the gearbox house. A simple and effective connection and disconnection of the ring gear and the gearbox house is thus obtained. According to one embodiment of the invention, the driving motor is disconnected from the input shaft with the coupling device. Thus, the input shaft's rotation is not impacted by the driving motor, which increases the possibility of quickly and efficiently changing gear positions in the auxiliary gearbox by way of reducing the rotational speed of the input shaft with the second braking device.

According to one embodiment of the invention, the driving motor is controlled towards a constant engine speed. Thus, an operating condition for the driving motor may be selected during the shifting operation, which results in high efficiency and a low energy requirement.

According to one embodiment of the invention, the rotational speed of the input shaft is reduced to a rotational speed below the engine speed of the driving motor. Thus, the driving motor may be operated with an engine speed that is favourable with respect to efficiency and energy requirement, at the same time as the input shaft, with the second braking device, may be reduced to a rotational speed below the engine speed of the driving motor, and which results in a possibility of changing gear positions in the auxiliary gearbox.

Other advantages of the invention are set out in the detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS Below is a description, as an example, of preferred embodiments of the invention with reference to the enclosed drawings, in which:

Fig. 1 shows a side view of a vehicle with a gearbox according to the present invention,

Fig. 2 shows a schematic section view of the transmission according to the invention in a high range position, Fig. 3 shows a schematic section view of the transmission according to the invention in a low range position, and

Fig. 4 shows a flow chart of a method to control a transmission according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Fig. 1 shows a side view of a vehicle 1, e.g. a truck, which comprises a transmission 3 according to the present invention. The transmission 3 comprises a driving motor 4, a main gearbox 6, a coupling device 5 arranged between the driving motor 4 and the main gearbox 6, an auxiliary gearbox 2 and a propeller shaft 10. The driving motor 4 is connected to the main gearbox 6, which in turn is connected to the auxiliary gearbox 2 according to the present invention. The auxiliary gearbox 2 is also connected to the driving wheels 8 of the vehicle 1 via the propeller shaft 10. The auxiliary gearbox 2 is also called a range gearbox, and its objective is to double the number of gearing possibilities. The auxiliary gearbox 2 is surrounded by a gearbox house 12.

Fig. 2 shows a schematic cross section view of a transmission 3 according to the pre- sent invention. The main gearbox 6 comprises an input shaft 7 connected to the coupling device 5, a countershaft 9 and a main shaft 26, which countershaft 9 is connected with the input shaft 7 and the main shaft 26 via a split gear 11 and a main gear 13, re- spectively. The split gear 11 comprises a set of gear sets si, s2 where the gear set si represents a low split position and the gear set s2 represents a high split position. The gear set si may be connected with and disconnected from the input shaft 7 via a first coupling element 15. The gear set s2 may be connected with and disconnected from the input shaft 7 via a second coupling element 17. When both coupling elements 15, 17 disconnect the first and the second gear sets si, s2, the split gear 11 is moved into a neutral position. The main gear 13 comprises a set of gear sets gl-g3, where the gear set gl represents a first gear, the gear set g2 represents a second gear and the gear set g3 represents a third gear. The gear sets gl - g3 may be connected and disconnected via a third, fourth and fifth coupling element 19, 21, 23, respectively.

The auxiliary gearbox 2 comprises a planetary gear 14, which has a low and a high gear, respectively, with which the main gearbox's 6 gearing possibilities may be divided into a low range position and a high range position. In a first gear position, which corresponds to the low range position, a down shift occurs via the planetary gear 14. In the second gear position, which corresponds to the high range position, the gearing is 1 : 1 in the planetary gear 14. Fig. 2 shows the auxiliary gearbox 2 in a second gear position, corresponding to the high gear or the high range gear. The auxiliary gearbox 2 is housed in the gearbox house 12 and is connected to the main shaft 26 of the main gearbox 6. The planetary gear 14 comprises three main components, which are arranged in a rotatable manner in relation to each other, namely a sun wheel 18, a planetary wheel carrier 20 and a ring gear 22. On the planetary wheel carrier 20, a number of mounted planetary wheels 24 are arranged. On the planetary wheel carrier 20 the auxiliary gearbox's 2 output shaft 28 is also arranged, which is connected to the propeller shaft 10 of the vehicle 1. With knowledge about the number of teeth 32 in the sun wheel 18 and the ring gear 22, the relative rotational speeds of the three components may be determined during operation. The sun wheel 18 is connected in a twist-fast manner with the main shaft 26, and the planetary wheels 24 en- gage in said sun wheel 18. The ring gear 22 envelops and engages in the planetary wheels 24. The teeth 32 of the sun wheel 18, the planetary wheels 24 and the ring gear 22 may be oblique, i.e. they may have an angle in relation to a rotational axis 30, common to the sun wheel 18, the planetary wheel carrier 20 and the ring gear 22. By cutting the teeth 32 obliquely, a reaction force in the direction of the rotational axis 30 is obtained from the cogwheels 18, 22, 24 comprised in the planetary gear 14. The direction of the reaction force is dependent on in which direction the teeth 32 in the planetary gear 14 are cut obliquely. Thus, the reaction forces may operate backwards or forwards along the extension of the rotational axis 30.

A first axially shiftable coupling sleeve 40 is arranged, in the first gear position, to disconnect the main shaft 26 from the planetary wheel carrier 20 and is arranged, in the second gear position, to connect the main shaft 26 with the planetary wheel carrier 20. A second axially shiftable coupling sleeve 42 is arranged to connect the gearbox house 12 surrounding the planetary gearbox 14 with the ring gear 22 in the first gear position, and is arranged to disconnect the gearbox house 12 from the ring gear 22 in the second gear position.

The first axially shiftable coupling sleeve 40 is equipped, on an inner surface, with first splines 44, which are arranged to interact with corresponding first splines 44 arranged on the main shaft 26 and the planetary wheel carrier 20. Corresponding first splines 44, arranged on the main shaft 26, have been manufactured on the periphery of a first ring 46, which is fitted in a twist-fast manner on the main shaft 26. The corresponding first splines arranged on the planetary wheel carrier 20, have been manufactured on the periphery of a second rim 48, which is fitted in a twist-fast manner on the planetary wheel carrier 20. The second axially shiftable coupling sleeve 42 is equipped with second splines 50 on an inner surface, which splines are arranged to interact with corresponding second splines 50, arranged on the periphery of the ring gear 22, and on a protrusion 52, which is fixedly connected with the gearbox house 12. The high gear of the auxiliary gearbox 2 is obtained by way of the first coupling sleeve 40 being shifted to connect the main shaft 26 with the planetary wheel carrier 20. The second coupling sleeve 42 is shifted in order to disconnect the ring gear 22 from the gearbox house 12. The second coupling sleeve 42 will accordingly be connected only with the gearbox house 12, which means that the second coupling sleeve 42 comes to a standstill and will not impact inertia forces at the rotation of the ring gear 22. Torque transmission from the main shaft 26 to the output shaft 28 therefore takes place via the main shaft 26 and the planetary wheel carrier 20, and further to the output shaft 28, so that the gearing ratio through the planetary gearbox 14 becomes 1 : 1.

The axial shifting of the first and second coupling sleeve 40, 42 is achieved with a first and second shift fork 58, 60, which are arranged in a groove 62 on the first and second sleeves' 40, 42 respective outside circumferences. The first shift fork 58 is impacted by a first power element 64, and the second shift fork 60 is impacted by a second power element 66. The first and second power elements 64, 66 may consist of a pneumatic or a hydraulic cylinder. The first and second shift forks 58, 60 and the first and second power elements 64, 66 are schematically drawn in Fig. 2.

Preferably, the respective coupling sleeves 40, 42 have a small mass, which entails that low energy and power is spent in moving the respective coupling sleeves 40, 42 when shifting gears. Thus, a quick shifting between the different gear positions in the auxiliary gearbox 2 may be carried out during a short time.

Fig. 3 shows a section view of the auxiliary gearbox 2 according to the invention in the first gear position or the low range position. The auxiliary gearbox's 2 low gear is obtained by way of axially shifting the first coupling sleeve 40 in order to disconnect the planetary wheel carrier 20 from the main shaft 26, at the same time as, or in close con- nection with, shifting the second coupling sleeve 42, so that the ring gear 22 is connected to the gearbox house 12.

By moving the first coupling sleeve to a position where it is in engagement only with the main shaft or the planetary wheel carrier, at the same time as the second coupling sleeve has been moved to a position where it is in engagement only with the gearbox house, the auxiliary gearbox will be shifted to a neutral state, in which no torque transmission occurs through the auxiliary gearbox. A first braking device 54 is arranged at the countershaft 9 in order to reduce the rotational speed of the countershaft 9 at shifting in the transmission 3, and a second braking device 56 is arranged at the input shaft 7, in order to reduce the rotational speed of the input shaft 7 at shifting in the transmission 3. Since the second braking device 56 is arranged at the input shaft 7 in order to reduce the rotational speed of the input shaft 7 at shifting in the transmission 3, a synchronous rotational speed or torque balance may be achieved in the auxiliary gearbox 2 with the objective of changing a gear position. The first and second braking devices 54, 56 may each consist of friction brakes, which are hydraulically, pneumatically and/or electrically controlled.

The transmission 3 according to the invention functions as follows in connection with shifting from the second to the first gear position, that is to say from the high range position to the low range position, and will be described in connection with Figures 2 - 3.

In Fig. 2 the driving motor 4 has been controlled towards a constant engine speed and an operating condition that is advantageous from an energy point of view. If the driving motor 4 is a combustion engine the fuel consumption will be minimal at the con- stant engine speed. The coupling device 5 has been controlled towards a disconnected state, which means that the driving motor 4 and the input shaft 7 are no longer connected, and no torque is transmitted. The split gear 11 has been moved to a neutral state, since the first and second coupling elements 15, 17 have been moved out of engagement with the respective gear sets si, s2. This is facilitated since the input shaft 7 is in torque balance with the respective gear sets si, s2 arranged on the input shaft 7. Thus, no torque is transmitted from the input shaft 7 to the respective gear sets si, s2. By decelerating the rotational speed of the input shaft with the second braking device 56, connection of the gear sets si, s2, which were not previously connected, is facilitated. When the input shaft 7 has been decelerated to a rotational speed, which coin- cides with the gear set si, s2, which was previously not connected, the first or the second coupling element 15, 17 will connect the gear set si or s2 with the input shaft. Thus, a new gear position has been engaged in the split gear 11. The gear sets gl-g3 of the main gear 13 have been moved to a neutral position, by way of disconnecting the gear sets gl-g3 from the main shaft 26 with the third, fourth and fifth coupling elements 16, 21, 23. This is possible since the main shaft 26 is in torque balance with the respective gear sets gl-g3, arranged on the main shaft 26. Thus, no torque is transmitted from the main shaft to the respective gear sets gl-g3. In order to engage a gear in the main gear 13, the countershaft 9 is decelerated with the first braking device 54, following which a suitable gear set gl-g3 is connected with the main shaft 26 through one of the third, the fourth or the fifth coupling element 19, 21, 23. This is facilitated when a synchronous rotational speed has been achieved between the main shaft 26 and the gear set gl-g3, which is to be connected with the main shaft 26. Thus, a new gear position has been engaged in the main gear 13.

Subsequently, the auxiliary gearbox is moved to a neutral state by way of shifting the first coupling sleeve 40 axially, in order to disconnect the planetary wheel carrier 20 from the main shaft 26. In order to be able to change gear positions in the auxiliary gearbox 2 to the low gear, the coupling device 5 is activated, so that the driving motor 4 is connected with the main gearbox 6, following which the driving motor is accelerated to an engine speed entailing that the ring gear 22 comes to a standstill in the auxil- iary gearbox 2. Finally, the gear position in the auxiliary gearbox 2 is changed to the low gear by shifting the second coupling sleeve 42, so that the ring gear 22 is connected to the gearbox house 12. Thus, a new gear positions has been engaged in the auxiliary gearbox 2. The new gear positions in the main gearbox 6 and the auxiliary gearbox 2 are displayed schematically in Fig. 3.

In this context, it should be mentioned that the input shaft 7 and the main shaft 26 may be connected, with the objective of obtaining a direct gear through the main gearbox 6. In such a direct gear position the gearing is 1 : 1 through the main gearbox 6 and the torque between the input shaft 7, and the main shaft 26 is transmitted via a direct con- nection between the input shaft 7 and the main shaft 26. In this direct gear position no torque is transmitted via the countershaft 9. The direct connection between the input shaft 7 and the main shaft 26 is implemented via the second coupling element 17 or the third coupling element 19. When the second coupling element 17 is brought out of engagement with the gear set s2, it may be shifted axially and engage with the main shaft 26, in order to transmit torque between the input shaft 7 and the main shaft 26. Alternatively, when the third coupling element 19 is brought out of engagement with the gear set gl, it may be shifted axially and engage with the input shaft 7, in order to transmit torque between the input shaft 7 and the main shaft 26. When the main gearbox 6 is moved to such a direct gear position, either the split gear 11 or the main gear 13 is moved to a neutral state, so that the gear 11 or 13 engaged makes the countershaft 9 rotate, but without the countershaft transmitting any torque between the input shaft 7 and the main shaft 26. Alternatively, both the split gear 11 and the main gear 13 are brought to a neutral position, so that the countershaft 9 comes to a standstill.

Fig. 4 shows a flow chart of a method to control the transmission 3 according to the present invention. The method comprises the steps:

a) deceleration of the input shaft 7 with a second braking device 56, which is arranged at the input shaft 7,

b) deceleration of the countershaft 9 with the first braking device 54, and

c) change of gear positions in the auxiliary gearbox 2. Preferably, the gear position is changed to a first gear in step c), in which a gear house 12 surrounding the planetary gear 14 is connected with the ring gear 22.

Before step a), the driving motor 4 is preferably disconnected from the input shaft 7 via a coupling device 5 in a step d).

After step a) and before step b), the gear position in the split gear 11 is preferably changed in a step e).

After step d) and before step a), the driving motor 4 is preferably controlled towards a constant engine speed in a step f). After step b) and before step c), the gear position in the main gearbox 13 is preferably changed in a step g).

After step g) and before step c), the driving motor 4 is preferably connected, in a step h), which the input shaft 7 via the coupling device 5, and the engine speed of the driving motor 4 is increased.

An electronic control device 70 is connected to the auxiliary gearbox 2, the main gearbox 6, the driving motor 4 and the clutch 68 to carry out the gear steps above. Prefera- bly a number of non-displayed rotational speed sensors in the auxiliary gearbox 2, the main gearbox 6 and the driving motor 4 may be connected to the control device 70. Another computer 72 may also be connected to the control device 70. The control device 70 may be a computer with software suitable for this purpose. The control device 70 and/or the computer 72 comprise a computer program P, which may comprise pro- cedures to control the auxiliary gearbox 2 according to the present invention. The program P may be stored in an executable manner, or in a compressed manner, in a memory M and/or a read/write memory R. Preferably, a computer program product is provided, comprising program code stored in a medium readable by a computer, in order to perform the gear steps specified above, when said program code is executed in the control device 70, or in another computer 72, connected to the control device 70. Said program code may be stored in a non-volatile manner on said computer-readable medium.

The components and features specified above may within the framework of the inven- tion be combined between different embodiments specified.

Claims

1. Transmission for vehicles, comprising a driving motor (4), a main gearbox (6), an auxiliary gearbox (2) and a coupling device (5), arranged between the driving motor (4) and the main gearbox (6), which main gearbox (6) comprises an input shaft (7) connected to the coupling device (5), a countershaft (9) and a main shaft (26), which countershaft (9) is connected with the input shaft (7)and the main shaft (26) via a split gear (11) and a main gear (13), respectively, and which auxiliary gearbox (2) comprises a planetary gear (14) with a ring gear (22), a sun wheel (18) and a planetary wheel carrier (20), on which at least one planetary wheel (24) is rotatably mounted, which ring gear (22) and sun wheel (18) through teeth (32)engage with the at least one planetary wheel (24), wherein the planetary gear (14) is connected with the main shaft (26) of the main gearbox (6), and wherein a first braking device (54) is arranged at the countershaft (9), in order to decelerate the countershaft (9) at shifting in the transmis- sion (3),

characterised in that:

a second braking device (56) is arranged at the input shaft (7), in order to decelerate the input shaft (7) at shifting in the transmission (3).

2. Transmission according to claim 1, characterised in that a first axially shiftable coupling sleeve (40), which is arranged, in the first gear position, to disconnect the main shaft (26) to the auxiliary gearbox (2) from the planetary wheel carrier (20), and, in the second gear position, to connect the main shaft (26) with the planetary wheel carrier (20); and

a second axially shiftable coupling sleeve (42), which is arranged, in the first gear position, to connect a gearbox house (12) surrounding the planetary gearbox (14) with the ring gear (22), and, in the second gear position, to disconnect the gearbox house (12) from the ring gear (22).

3. Transmission according to any of claims 1 - 2, characterised in that the main shaft (26) of the main gearbox (6) is connected to the sun wheel (18) of the planetary gear and in that the planetary wheel carrier (20) is connected with an output shaft (28) of the auxiliary gearbox (2).

4. Transmission according to any of the previous claims, characterised in that the first axially shiftable coupling sleeve (40) is equipped on an inner surface with first splines (44), which are arranged to interact with corresponding first splines (44) arranged on the main shaft (26) and the planetary wheel carrier (20).

5. Transmission according to any of the previous claims, characterised in that the second axially shiftable coupling sleeve (42) is equipped on an inner surface with second splines (50), which are arranged to interact with corresponding second splines (50) arranged on the ring gear (22) and on the gearbox house (12).

6. Transmission according to any of the previous claims, characterised in that the auxiliary gearbox (2) is a range gearbox.

7. Vehicle (1), characterised in that it comprises a transmission (3) according to any of the claims 1-6.

8. Method to change gears in a transmission (3) for vehicles, comprising a driving motor (4), a main gearbox (6), an auxiliary gearbox (2) and a coupling device (5), arranged between the driving motor (4) and the main gearbox (6), which main gearbox (6) comprises an input shaft (7) connected to the coupling device (5), a countershaft (9) and a main shaft (26), which countershaft (9) is connected with the input shaft (7) and the main shaft (26) via a split gear (11) and a main gear (13), respectively, and which auxiliary gearbox (2) comprises a planetary gear (14) with a ring gear (22), a sun wheel (18) and a planetary wheel carrier (20), on which at least one planetary wheel (24) is rotatably mounted which ring gear (22) and sun wheel (18) through teeth (32) engage with the at least one planetary wheel (24), wherein the planetary gear (14) is connected with the main shaft (26) of the main gearbox (6), and wherein a first braking device (54) is arranged at the countershaft (9), in order to decelerate the countershaft (9) at shifting in the transmission (3), characterised in that the method comprises the following steps:

a) deceleration of the input shaft (7) with a second braking device (56), which is arranged at the input shaft (7),

b) deceleration of the countershaft (9) with the first braking device (54), and c) change of gear positions in the auxiliary gearbox (2).

9. Method according to claim 8, characterised in that the gear position in step c) is changed to a first gear position, in which a gearbox house (12) surrounding the planetary gear (14) is connected with the ring gear (22).

10. Method according to any of claims 8-9, characterised in that, before step a): d) the driving motor (4) is disconnected from the input shaft (7) via a coupling device (5).

11. Method according to any of claims 8 - 10, characterised in that , after step a) and before step b):

e) gear positions are changed in the split gear (11).

12. Method according to claim 10, characterised in that, after step d) and before step a):

f) the driving motor (4) is controlled towards a constant engine speed.

13. Method according to any of claims 8 - 12, characterised in that , after step b) and before step c): g) gear positions are changed in the main gearbox (13).

14. Method according to claim 13, characterised in that , after step g) and before step c) : h) the driving motor (4) is connected with the input shaft (7) through the coupling device (5) and the driving motor's (4) engine speed is increased.

15. Computer program product, comprising a program code stored in a medium readable by a computer, in order to perform the method steps according to any of claims 8 - 14, wherein said program code is executed in an electronic control device (48) or in another computer (53) connected to the electronic control device (48).