BR102017008772A2 - CHANGING THE GEAR RELATION IN A VEHICLE GEARBOX - Google Patents

Abstract

changing gear ratio in a gearbox of a vehicle. The invention relates to a method for changing the gear ratio in a gearbox (2) of a vehicle (1), said gearbox (2) being arranged to transfer torque between a power source (4) and at least one gear. at least one drive wheel (8) of said vehicle (1), said gearbox (2) comprising a first gearbox device (15a) and at least a second gearbox device (15b), being each of said first and second gearbox devices (15b) individually controllable to engage at least two gears with different gear ratios to form a combined gear ratio of said gearbox (2), said second gearbox device gearbox (15b) disposed between said first gearbox device (15b) and said at least one drive wheel (8). the method comprising the steps of: disconnecting said first and second gearbox devices (15a, 15b) from said gearbox (2) from said at least one drive wheel (8); changing the gear ratio of said second gearbox device (15b) when said first and second gearbox devices (15a, 15b) of said gearbox (2) are disconnected from said at least one drive wheel (8); and - synchronizing the rotational speed between a rotating element (20, 22) of said second gearbox device (15b) and said at least one drive wheel (8) when said gear ratio of said second gearbox device. gearbox (15b) has been changed. The invention also relates to a computer program comprising a program code, a system for changing the gear ratio in a gearbox (2) of a vehicle (1), and a vehicle (1).

Description

(54) Title: CHANGING THE GEAR IN A VEHICLE GEARBOX (51) Int. Cl .: F16H 61/70; F16H 63/44; F16H 37/04 (52) CPC: F16H 61/702, F16H 61/70, F16H 63/44, F16H 37/046 (30) Unionist Priority: 05/23/2016 SE 1650701-4 (73) Holder (s) : SCANIA CV AB (72) Inventor (s): TOMAS SELLING; PER ARNELÕF; PEER NORBERG (74) Attorney (s): LUIZ LEONARDOS & ADVOGADOS (57) Summary: CHANGING THE GEAR RELATIONSHIP IN A VEHICLE'S GEAR BOX. The invention relates to a method for changing the gear ratio in a gearbox (2) of a vehicle (1), said gearbox (2) being arranged to transfer power between a power source (4) and at least at least one drive wheel (8) of said vehicle (1), said gearbox (2) comprising a first gearbox device (15A) and at least a second gearbox device (15B), being each of said first and second gearbox devices (15B) individually controllable to engage at least two gears with different gear ratios to form a combined gear ratio of said gearbox (2), said second gear device of gear (15B) disposed between said first gearbox device (15B) and said at least one drive wheel (8). The method comprising the steps of: - disconnecting said first and second gearbox devices (15A, 15B) from said gearbox

1/28 “CHANGING THE GEAR IN A VEHICLE'S GEARBOX”

BACKGROUND AND PRECEDENT TECHNIQUE [0001] The invention relates to a method for changing the gear ratio in a vehicle's gearbox, a system for changing the gear ratio in a vehicle's gearbox, a computer program , a computer program product and a vehicle according to the appended claims.

[0002] Vehicles, and in particular, heavy goods vehicles, are normally equipped with a gearbox connected to a power source, such as an internal combustion engine, an electric motor or a combination thereof. The gearbox can be automatic, manual or a combination of them. In an automated manual transmission, the so-called AMT gearbox, the gearbox is controlled by an electronic control device. Such a gearbox can be equipped with a main gearbox device provided with a main shaft. An intermediate axis is arranged in parallel with the main axis. The main shaft is coupled to an input shaft via the intermediate shaft and to an output shaft in the gearbox via a gearbox extension device, if such a gearbox extension device is integrated in the gearbox . The gearbox extension device can be a separate device instead of being integrated into the gearbox. The gearbox can also be equipped with a split gear device, arranged between the input shaft and the intermediate shaft.

[0003] A brake mechanism can be arranged to slow the intermediate shaft in connection with the gear change in the gearbox, in order to achieve synchronous rotation speeds between the intermediate shaft and the main shaft, so that the new gear can be engaged without any difference in the speed of rotation between those parts of the transmission in the gearbox which are caused to engage with each other at the moment when the

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2/28 new gear is engaged. The brake mechanism is then used to slow the intermediate shaft relative to the main shaft by one step during a shift operation when the main gearbox is in the neutral position, while the intermediate shaft is disconnected from the main shaft. Also, a similar brake mechanism can be arranged to slow the main shaft in connection with changing gear in the gearbox.

[0004] In gearboxes of this type, the synchronization devices, which include tapered synchronization rings and coupling rings, can be replaced by coupling sleeves provided with grooves that are axially displaced to engage with gear wheels placed on the main shaft. . Each gear wheel placed on the main shaft is engaged with corresponding gear wheel elements, which are firmly attached to the intermediate shaft. When changing, the coupling sleeve is moved axially to engage with coupling teeth arranged on a selectable gear wheel, in order to connect the gear wheel to and lock it in rotation with the main shaft. The synchronization device in the split gearbox device and the gearbox extension device can also be replaced by coupling sleeves.

[0005] The synchronization between the gear wheels and axles in the gearbox is for some gear changes provided by the power source. The power source accelerates the gear wheel or shaft to be connected with each other. When synchronization has been achieved, the gear wheel and shaft are connected via the coupling sleeve.

[0006] The gearbox extension device is normally supplied between the main gearbox device and an impeller shaft coupled to the vehicle's drive wheels. The gearbox extension device is housed in a gearbox housing and comprises an input shaft coupled to the main gearbox device, an output shaft, and between the input shaft and the output shaft exists A planetary gear of the gearbox extension device is arranged. THE

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3/28 planetary gear normally comprises three components, which are rotatably arranged relative to each other, namely, a sun gear wheel, a planetary wheel carrier with planetary gear wheels and an annular gear wheel. With the knowledge of the number of teeth of the sun gear wheel and the ring gear wheel, the relative speed of the three components can be determined during operation. In a gearbox extension device, the sun gear wheel can be rotatably connected to the input shaft, a number of planetary gear wheels that engage said sun gear wheel, whose planetary gear wheels are rotatably mounted on the planetary wheel carrier that is fixedly connected to the output shaft and an axially displaceable ring gear wheel that surrounds and engages the planetary gear wheels. The teeth of the sun gear wheel, planetary gear wheels and ring gear wheel can be helical, that is, they are arranged at an angle to a common axis of rotation of the sun gear wheel, planetary wheel carrier and gear wheel. ring gear.

[0007] There are extension gearboxes in which the synchronization devices are replaced by coupling sleeves with grooves. By controlling the transmission for synchronous speed between the two components to be engaged, an axial displacement of the coupling sleeve is made possible to connect them. When components must be disengaged, the transmission is controlled so that torque balance occurs between the components, so that the coupling sleeve is not transmitting torque. It is then possible to move the coupling sleeve axially to disengage the components from each other.

[0008] Document US6196944 shows a planetary gear comprising a sun gear wheel, a planetary wheel carrier with planetary gear wheels and a ring gear wheel. The sol gear wheel can be connected to the input shaft by means of a coupling sleeve in a low gear position and disengaged from the input shaft in a position 870170027859, from 04/27/2017, p. 47/88

4/28 high gear. In the high gear position, the input shaft is connected to the planetary wheel carrier by means of the same coupling sleeve. The gear wheel is firmly connected to a gearbox housing. The known planetary gear is arranged in an auxiliary gearbox, having only two running positions.

[0009] US 6196944 shows a gearbox for motor vehicles comprising a planetary gear comprising a first and a second sleeves which act on the planetary wheel carrier, the ring gear wheel, the gearbox housing and the output shaft. The first and second gloves are controlled as a connected unit.

[0010] The synchronous speed and torque balance between the components that must be engaged and disengaged when changing gears can be achieved by controlling the power source in the transmission. However, when the power source is an internal combustion engine, the amount of time to synchronize when shifting gears can be very long depending on the inertia in controlling the engine. As a result, the internal combustion engine will not reach the final speed for synchronous gear shifting in the gearbox.

SUMMARY OF THE INVENTION [0011] Despite known solutions, there is a need to further develop a gearbox that is less dependent on the power source when shifting gears. There is also a need to further develop a gearbox in which the time for change is short.

[0012] An objective of the invention is, therefore, to provide a gearbox that is less dependent on the energy source when changing gears.

[0013] Another objective of the invention is to provide a gearbox in which the time period for changes is short.

[0014] The objectives mentioned here, and other objectives, are achieved by a method to change the gear ratio in a gearbox of a vehicle, a system to change the gear ratio in a gearbox 870170027859, of 27 / 04/2017, p. 48/88

5/28 gears of a vehicle, a computer program, a computer program product and a vehicle according to the independent claims.

[0015] According to one aspect of the present invention, a method is provided for changing the gear ratio in a vehicle gearbox. The gearbox is arranged to transfer torque between a power source and at least one drive wheel of said vehicle. The gearbox comprises a first gearbox device and at least a second gearbox device, each said first and second gearbox device being individually controllable to engage at least two gears with different gear ratios for forming a combined gear ratio of said gearbox. The second gearbox device is disposed between said first gearbox device and said at least one drive wheel. The method comprises the steps of:

i. - disconnecting said first and second gearbox devices from said gearbox from said at least one drive wheel;

ii. - changing the gear ratio of said second gearbox device when said first and second gearbox devices of said gearbox are disconnected from said at least one drive wheel; and iii. - synchronizing the speed of rotation between a rotating element of said second gearbox device and said at least one drive wheel when said gear ratio of said second gearbox device has been changed.

[0016] The step of disconnecting said first and second gearbox devices from said gearbox from said at least one drive wheel comprises disconnecting rotating parts of the first and second gearbox devices from said at least one wheel drive, so that no torque or speed can be transferred to the first and second gearbox devices from said at least one

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6/28 activation. The step of changing the gear ratio of said second gearbox device when said first and second gearbox devices of said gearbox are disconnected from said at least one drive wheel comprises making an upward shift or a down shift on the second gearbox device, depending on the driving conditions of the vehicle. The step of synchronizing the speed of rotation between a rotating element of said second gearbox device and said at least one drive wheel when said gear ratio of said second gearbox device has been changed, comprises accelerating the element rotating said second gearbox device in order to synchronize the speed of rotation between the rotating element of said second gearbox device and said at least one drive wheel, to prepare a connection between the second gearbox device gears and at least one drive wheel.

[0017] The process steps can be carried out and / or controlled by means of a control unit connected to the power source and the gearbox. [0018] According to one aspect of the present invention, the step of changing the gear ratio of said second gearbox device when said first and second gearbox devices of said gearbox are disconnected from said at least a drive wheel, also comprises the steps of:

i. - disconnecting said second gearbox device from said first gearbox device by displacing said first gearbox device to a neutral running position;

ii. - applying a braking force to the rotating element of said second gearbox device by means of a first braking element;

iii. changing the gear ratio of said second gearbox device when said rotating element of said second gearbox device is in an immobilized condition.

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[0019] The step of disconnecting said second gearbox device from said first gearbox device by displacing said first gearbox device to a neutral gear position comprises disconnecting rotating parts of the second gearbox device from the first gearbox device so that no torque or speed can be transferred from the first gearbox device to the second gearbox device. The step of applying a braking force to the rotating element of said second gearbox device by means of a first braking element comprises slowing the speed of the rotating element of said second gearbox device to a standstill condition. The step of changing the gear ratio of said second gearbox device when said rotating element of said second gearbox device is in an immobilized condition comprises making an upward change or a downward change in the second gearbox device of gears depending on the driving conditions of the vehicle.

[0020] In accordance with an aspect of the present invention, the method further comprises the steps of:

i. - accelerating a rotating element of said first gearbox device by means of said energy source after connecting said gearbox to at least one drive wheel;

ii. - changing the gear ratio of said first gearbox device when the rotation speed of said rotating element has been accelerated to at least a first speed.

[0021] The step of accelerating a rotating element of at least one of said first gearbox device by means of said energy source when changing the gear ratio of said second gearbox device or after connecting said gearbox gears to said at least one drive wheel, comprises synchronizing the speed between rotating elements within said first gearbox device. The step of changing

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8/28 gear ratio of at least one of said first gearbox device when the rotation speed of said rotating element has been accelerated to at least a first speed comprises making a downward shift in said first gearbox device .

[0022] In accordance with an aspect of the present invention, the method further comprises the steps of:

i. - applying a braking force to a rotating element of said first gearbox device by means of a second braking element, then connecting said gearbox to at least one drive wheel;

ii. - changing the gear ratio of at least one of said gearbox devices when the speed of rotation of said rotating element has been reduced at least to a second speed.

[0023] The step of applying a braking force to a rotating element of said first gearbox device by means of a second braking element, when changing the gear ratio of said second gearbox device or after connecting said gearbox to said at least one drive wheel, comprises synchronizing the speed between rotating elements within said first gearbox device. The step of changing the gear ratio of said first gearbox device when the rotation speed of said rotation element has been reduced at least to a second speed, comprises making an upward change in said first gearbox device.

[0024] According to an aspect of the present invention, said second gearbox device is an extended gearbox comprising a planetary gear, arranged to provide a high gear and a low gear. The step that disconnects said first and second gearbox devices from said gearbox from said at least one drive wheel, further comprises a step of:

[0025] - disconnect said planetary gear from said at least one wheel

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9/28 of activation.

[0026] The step of disconnecting said planetary gear from said at least one drive wheel comprises disconnecting rotating parts of the planetary gear from said at least one driving wheel, so that no torque or speed can be transferred to the planetary gear from at least one drive wheel.

[0027] According to one aspect of the present invention, the planetary gear comprises a sun wheel that is connected to an output shaft of said first gearbox device, and a planetary wheel carrier that carries a plurality of planetary wheels that engage said sun wheel, said planetary wheel carrier being selectively connectable to an output shaft of said second gearbox device. The step that disconnects said planetary gear from said at least one drive wheel, also comprises a step of:

i. - disconnecting said planetary wheel carrier from said output shaft of said second gearbox device.

[0028] The step of disconnecting said planetary wheel carrier from said second gearbox device comprises disconnecting the rotating parts of the planetary wheel carrier from said output shaft, so that no torque or rotation from of at least one drive wheel can be transferred to the planetary wheel carrier from said output shaft.

[0029] According to an aspect of the present invention, an axially displaceable coupling sleeve in a first position is arranged to connect said planetary gear to said at least one driving wheel of said vehicle, and in a second position it is arranged to disconnect said planetary gear of said at least one driving wheel of said vehicle. The method also comprises a stage of:

i. - synchronize the rotation speed between said planetary gear and said at least one drive wheel by means of a synchronization elementPetition 870170027859, of 27/04/2017, pg. 53/88

10/28 tion and, thereafter, ii. - connect said planetary gear to said at least one drive wheel.

[0030] The step of synchronizing the rotation speed between said planetary gear and said at least one drive wheel by means of a synchronization element comprises accelerating the rotation element of said planetary gear from an immobilization condition to synchronize the speed of rotation between the rotating element of said planetary gear and said at least one driving wheel that rotates when the vehicle moves. The step of connecting said planetary gear to at least one driving wheel comprises moving the coupling sleeve to the first position to connect the planetary gear to said at least one driving wheel.

[0031] In accordance with an aspect of the present invention, the method further comprises a step of:

i. - connecting said gearbox to said at least one drive wheel connecting said gearbox to an impeller shaft of said vehicle.

[0032] The step of connecting said gearbox to said at least one drive wheel connecting said gearbox to an impeller shaft of said vehicle comprises making a connection to transfer torque and rotation from the gearbox to at least a drive wheel, connecting said gearbox to an impeller shaft disposed between the gearbox and at least one drive wheel.

[0033] A control unit can be connected to the transmission such as the power source, a clutch and the gearbox, to achieve the upshift. The control unit can be the engine control unit or it can comprise a plurality of different control units. A computer can be connected or be part of the control unit.

[0034] In accordance with one aspect of the invention, a system is provided for changing the gear ratio in a vehicle gearbox. THE

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11/28 gearbox being arranged to transfer torque between a power source and at least one drive wheel of said vehicle, said gearbox comprising a first gearbox device and at least a second gearbox device, each of said first and second gearbox devices being individually controllable to engage at least two gears having different gear ratios to form a combined gear ratio of said gearbox, said second gearbox device being arranged between said first gearbox device and said at least one drive wheel. The system comprises:

i. - means for disconnecting said first and second gearbox devices from said gearbox from said at least one drive wheel;

ii. means for changing the gear ratio of said second gearbox device when said first and second gearbox devices of said gearbox are disconnected from said at least one drive wheel; and iii. means for synchronizing the speed of rotation between a rotating element of said second gearbox device and said at least one drive wheel when said gear ratio of said second gearbox device has been changed.

[0035] The means for disconnecting said first and second gearbox devices of said gearbox of said at least one drive wheel may comprise a second displaceable coupling sleeve. The second displaceable coupling sleeve can be displaced by means of a second pneumatic, hydraulic or electric actuator.

[0036] The means for changing the gear ratio of said second gearbox device, when said first and second gearbox devices of said gearbox are disconnected from said at least one drive wheel, may comprise a first action glovePetition 870170027859, of 04/27/2017, p. 55/88

12/28 displaceable device. The first displaceable coupling sleeve can be displaced by means of a first pneumatic, hydraulic or electric actuator.

[0037] The means for synchronizing the speed of rotation between a rotating component of said second gearbox device and said at least one drive wheel when said gear ratio of said second gearbox device has been changed accelerate the rotating element of said second gearbox device, so that the rotating element of said second gearbox device will achieve the same rotation speed as an impeller shaft connected to said at least one drive wheel. The means for synchronizing the speed of rotation between a rotating element of said second gearbox device and said at least one drive wheel may comprise a synchronizing element. [0038] According to an aspect of the invention, said second gearbox device is an extended gearbox comprising a planetary gear, arranged to provide a high gear and a low gear and where an axially displaceable coupling sleeve in one the first position is arranged to connect said planetary gear to said at least one driving wheel of said vehicle and, in a second position it is arranged to disconnect said planetary gear from at least one driving wheel of said vehicle. The system also comprises:

i. - a synchronization element for synchronizing the speed of rotation between said planetary gear and said at least one driving wheel before connecting said planetary gear to said at least one driving wheel.

[0039] The synchronizing element can accelerate the planetary gear of said second gearbox device, so that the rotating element of said second gearbox device will achieve the same rotation speed as the impeller shaft connected to said gearbox. least one drive wheel. The synchronization element can be provided with friction surfaces arranged on the planetary gear and on an output shaft connected to the

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13/28 impeller shaft. A frictional force between the friction surfaces will force the planetary gear to rotate at the same speed as the impeller shaft connected to said at least one drive wheel. Friction surfaces can be conical in shape. However, another form of the friction surfaces is also possible.

[0040] According to an aspect of the invention, the synchronization element is a friction clutch arranged between said planetary wheel carrier and an output shaft of said second gearbox device, whose output shaft is connected to the impeller shaft . The system also comprises:

i. - means for synchronizing the speed of rotation between said planetary gear and said output shaft of said second gearbox device, engaging the friction clutch.

ii. The means for synchronizing the speed of rotation between said planetary gear and said output shaft of said second gearbox device engaging the friction clutch comprise pneumatic, hydraulic or electric controlled actuators.

[0041] According to one aspect of the invention, the synchronization element is an electric machine arranged to rotate said planetary wheel carrier. The system also comprises:

i. - means for synchronizing the speed of rotation between said planetary gear and said at least one drive wheel, activating the electric machine to a speed that rotates said planetary gear with a speed that substantially corresponds to the speed of said output shaft of said second gearbox device.

[0042] The electric machine can be connected to the planetary gear so as to be able to rotate said planetary gear with a speed that substantially corresponds to the speed of said output shaft of said second gearbox device.

[0043] Other advantages of the invention appear from the detailed description that follows.

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BRIEF DESCRIPTION OF THE DRAWINGS [0044] Below is a description of, as examples, preferred embodiments of the invention with reference to the accompanying drawings, in which:

[0045] Figure 1 schematically illustrates a vehicle according to one embodiment of the invention, [0046] Figure 2 schematically illustrates a transmission according to one embodiment of the invention, [0047] Figure 3 schematically illustrates a transmission according to one embodiment of the invention in a low gear position, [0048] Figure 4 schematically illustrates a transmission according to an embodiment of the invention in a low gear position, [0049] Figure 5 schematically illustrates a transmission according to an embodiment of the invention in a high gear position.

[0050] Figure 6 schematically illustrates a transmission according to an alternative embodiment of the invention, [0051] Figure 7 schematically illustrates a flowchart for a method for changing the gear ratio in a vehicle gearbox, according to a first embodiment of the invention, and [0052] Figure 8 schematically illustrates a flowchart for a method for changing the gear ratio in a vehicle gearbox, according to a second embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION [0053] Figure 1 schematically illustrates a vehicle 1 according to an embodiment of the invention. Vehicle 1 includes a transmission 3, comprising a power source 4, such as an internal combustion engine, a gearbox 2, and an impeller shaft 10. The combustion engine 4 is coupled to gearbox 2. A gearbox 2 is further connected to the driving wheels 8 of the vehicle 1 via the impeller shaft 10. The gearbox 2 of the present invention comprises an extended gearbox. Here is done

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15/28 reference to various transmission on / off positions 3. In this context, the term upstream refers to a position in the direction of the power source 4, and the term downstream refers to a position in the direction of the drive wheels 8.

[0054] Figure 2 schematically shows a part of the transmission 3 comprising the combustion engine 4 and a clutch 11. The figure further discloses gearbox 2, which comprises three gearbox units 15A, 15B, 15C. A first gearbox unit 15A constitutes a conventional main gearbox that can be adjusted for three different forward gear ratios. The figure further describes a second gearbox unit 15B which constitutes an extended gearbox, disposed downstream of the main gearbox unit 15A. The extended gearbox unit 15B is surrounded by a gearbox housing 12 and is discussed further below with reference to figures 3 - 5. A third gearbox unit 15C is located upstream of the main gearbox 15B in the direction of the torque of the combustion engine 4 for the drive wheels 8. The third gearbox unit 15C constitutes a split gearbox that provides for each gearing of the main gearbox two gear steps with different gear ratios for provide more gear ratios from the gearbox 2.

[0055] Instead of a detachable clutch 11, an arrangement with first and second electric machines (not disclosed) can be arranged to rotate and brake a planetary gear (not disclosed) arranged in transmission 3 and located upstream of gearbox 2 In such an arrangement, the first electric machine should be arranged on a sun gear wheel (not disclosed) of the planetary gear, and the second electric machine should be arranged on the first ring gear wheel (not disclosed) of the planetary gear. The first and second electric machines can be the energy source or they can be part of the energy source.

[0056] With respect to the main gearbox 15A, an intermediate shaft

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202 comprises gear wheels 203A, 204A, 205A which are rotatably attached to the intermediate shaft 202. For example, gear wheel 203A represents the first gear, gear wheel 204A the second gear and gear wheel 205A the third gear. A main shaft 206 comprises corresponding gear wheels 203B, 204B, 205B that rotate freely relative to the main shaft 206, but which can be selectively locked for rotation with the main shaft 206 in order to engage a gear. For example, the main gear of the main gearbox can be engaged by maneuvering a first main sleeve 207, arranged to rotate with the main shaft 206, to a position in which the gear wheel 203B is engaged, that is, to the left in the figure, thereby bringing gear wheel 203B to rotate main shaft 206 and thereby also engaging intermediate shaft 202 to main shaft 206 through gear wheel 203A. Each pair of gear wheels on the intermediate shaft 202 and the main shaft 206 represent a gear ratio.

[0057] The second gear of the main gearbox can be engaged by disengaging the first main sleeve 207 from gear wheel 203B and instead displacing a second main sleeve 208 to a position to the right in the figure where, instead, the wheel of gear 204B is engaged, thereby engaging wheel 204B to rotate main shaft 206. Correspondingly, the third gear of the main gearbox can be engaged by maneuvering the second main sleeve 208 to a left position in the figure in which, when instead, the 205B gear wheel is engaged, thereby adjusting the main gearbox for third gear. Each of the first to third gears is used for a plurality of the total number of gears provided by gearbox 2 as a whole. For example, the first gear of the main gearbox 15A will be used for the first and second gears of gearbox 2, low and high, low, and also for seventh and eighth gears, low and high, high, from a way well known to those skilled in the art.

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17/28 [0058] Furthermore, with respect to the split gearbox 15C, the intermediate shaft 202 comprises an additional gear wheel 209A which, similar to the above, is rotatably attached to the intermediate shaft 202. An input shaft 201 comprises a corresponding gear wheel 209B, which rotates freely in relation to the input shaft 201, but which can be selectively locked for rotation with the input shaft 201 through a split sleeve 210, which can be provided with a split synchronization unit. Split sleeve 210 can further be used to connect gearbox input shaft 201 to gear wheel 205B directly. The pair of gear wheels 209AB and the coupling unit 210 can thereby provide two different gear ratios divided for each gear of the main gearbox into two parts.

[0059] When, for example, the first gear is engaged, the split sleeve 2 10 is arranged to engage the gear wheel 205B. This will result in the input shaft 201 being directly connected to the gear wheel 205B which, through the gear wheel 205A, establishes a first gear relationship between the input shaft 201 and the intermediate shaft 202. The gear wheel 205B , however, is not connected to the main shaft 206, but the intermediate shaft 202 is connected to the main shaft 206 through the pair of gear wheels 203A-B.

[0060] When the second gear is engaged, that is, the high split of the first gear of the main gearbox, vehicle 1 is instead driven with the pair of gear wheels 209A-B engaged, resulting in a second gear ratio between an input shaft 201 and the intermediate shaft 202 The gear wheel 203B is further engaged by the first main sleeve 207 according to the above, thereby extending the length of each gear.

[0061] This division can be performed for each gear of the main gearbox 15A, where the coupling unit 210 engages the gear wheel 205B and also the second main sleeve 208 engages the gear wheel

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205Β a gear ratio of 1: 1 is obtained through gearbox units 15C, 15A.

[0062] Also, the main shaft 206 can be provided with a first braking element 212, such as a main shaft brake, which is used to brake the main shaft 206 and also a planetary gear 14 (figure 3) in the gearbox. extended gears 15B to a standstill condition when shifting gears in the extended gearbox 15B. The intermediate shaft 202 may be provided with a second braking element 211, such as an intermediate shaft brake to decrease the speed of the intermediate shaft 202 during upward shift in the gearbox 103.

[0063] Until now, gearbox units 15A, 15C have been described. It should be understood that figure 2 only discloses an example of a design of such gearbox units, and that the present invention can be used for several different designs of such gearbox units. For example, the split gearbox 15C can be omitted. As explained below, the invention can be used for any gearbox 2 comprising a plurality of gearbox units that can be disconnected from both the power source 4 and the drive wheels 8 of the vehicle 1. However, perhaps the invention it is particularly well suited for use in a system in which an extended gearbox 15B, comprising for example a planetary gear 14, is used and can be disconnected from the driving wheels 8 of the vehicle 1.

[0064] Figure 3 schematically illustrates a transmission 3 according to an embodiment of the invention in a low gear position. The gearbox 2 comprises a planetary gear 14 that has a low gear and a high gear, so that the changing capacity of the main gearbox 15A can be divided into a low gear position and a high gear position. In a first gear position that corresponds to the low gear position, a gear ratio of less than 1: 1 is provided on the planetary gear 14. In the high gear position the gear ratio is 1: 1

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19/28 on planetary gear 14. Figure 3 shows gearbox 2 in the first gear position, corresponding to the low gear position. The extended gearbox 15B is used to double the number of gear ratios that are available from the main gearbox 15A and also, as in this case, the number of gears available from the combination gearbox units 15A , 15C. The gearbox unit 15B is, as shown in the figures, arranged downstream of the main gearbox 15A as seen from the combustion engine 4.

[0065] The gearbox 2 is housed in the gearbox housing 12 and comprises an input shaft 16 which can be a main shaft 26 of the main gearbox 15A. The planetary gear 14 comprises three main components which are rotatably arranged in relation to each other, namely, a planetary gear wheel 18, a planetary wheel carrier 20 and a ring gear wheel 22. Various planetary wheels 24 are rotatably arranged with bearings on the planetary wheel carrier 20. With knowledge of the number of teeth 32 of the sun gear wheel 18 and the ring gear wheel 22, the relative gear ratio of the three components can be determined. The gear wheel sol 18 is rotatably connected to the input shaft 16 and the planet gear wheels 24 engage the planet gear wheel 18. The gear wheel ring 22 wraps and engages the planet gear wheels 24. The teeth 32 of the wheel gear wheels 18, the planetary gear wheels 24 and the respective gear wheel 22 can be chamfered so that they have an angle to a common axis of rotation 30 of the gear wheel sun 18 of the planetary gear carrier 20 and the gear wheel 22. The input shaft 16 can be connected to the sun gear wheel 18 by means of a grooved connection 34.

[0066] A first axially displaceable coupling sleeve 42 is in a first gear position, arranged to connect the gearbox housing 12 with the ring gear wheel 22 and in a second gear position arranged to disconnect the gear housing gears 12 of the gear wheelPetition 870170027859, of 27/04/2017, p. 63/88

20/28 ning ring 22. The first axially movable coupling sleeve 42 is in the first running position arranged to disconnect the input shaft 16 from the planetary wheel carrier 20.

[0067] An engagement element in the form of a second axially displaceable coupling sleeve 43 is in a first position arranged to disconnect the planetary wheel carrier 20 from an output shaft 28 from gearbox 2, whose output shaft 28 is coupled to the drive shaft 10 of the vehicle 1. In a second position, the second axially displaceable coupling sleeve 43 is arranged to connect said gearbox 2 to said at least one drive wheel 8 of said vehicle 1.

[0068] In this position, disclosed in figure 3, the second axially displaceable coupling sleeve 43 transfers torque from the planetary wheel carrier 20 to the impeller shaft 10 and also to the driving wheels of the vehicle 1. The second axially displaceable coupling sleeve 43 thus forms an engagement element between gearbox 2 and drive wheels 8.

[0069] The second axially displaceable coupling sleeve 43 can, in a third gearing position, couple the gear wheel ring 22 with the output shaft 28 of gearbox 2 and thus achieve an inverted gear. In the third gear position, corresponding to the inverted gear, the first axially displaceable coupling sleeve 42 is arranged to disconnect the input shaft 16 from the planetary wheel carrier 20 and is instead arranged to interconnect the planetary wheel carrier 20 with gearbox housing 12.

[0070] The first coupling sleeve 42 is provided with first grooves 50 on an inner periphery of the sleeve 42 and second grooves 51 on an outer periphery of the sleeve 42. The first grooves 50 arranged on the inner periphery of the sleeve 42 interact with corresponding first cooperating grooves 50 'arranged on the input shaft 16. Corresponding first cooperating grooves 50' arranged on the input shaft 16 are made on the periphery of a first toothed wheel 46, which is mounted on the input shaft 16. The first grooves 50

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21/28 on the inner periphery of the sleeve 42 are also arranged to cooperate with corresponding first cooperating grooves 50 ”arranged in the carrier of the planet wheel 20. Corresponding first cooperating grooves 50” arranged in the carrier of the planet wheel 20 are made on the periphery of a second gear 44 which is mounted on the planetary wheel carrier 20. The second grooves 51 arranged on an outer periphery of the sleeve 42 interact with corresponding second cooperating grooves 51 'arranged on the projection 52 which is fixedly connected to the housing of the housing gears 12.

[0071] The second axially displaceable coupling sleeve 43 is on an inner surface provided with third grooves 59 which are arranged to cooperate with the corresponding second cooperating grooves 59 ', 59 ”, 59'”, arranged on the gear wheel ring 22, on the planetary wheel carrier 20 and on the output shaft 28, respectively. The corresponding second cooperating slots 59 arranged on the planetary wheel carrier 20 are formed on the periphery of a third gearwheel 49 which is mounted on the planetary wheel carrier 20. The corresponding second cooperating grooves 59 provided on the output shaft 28 are formed on the periphery of a fourth gear wheel 53 which is mounted on the output shaft 28.

[0072] An axial stop 54 disposed on the planetary wheel carrier 20 is adapted to bump against the gear wheel ring 22, whose axial stop 54 prevents the gear wheel ring 22 from being displaced axially. The thrust stop 54 may comprise a disc-shaped plate which, by means of a first thrust bearing 56, is mounted on the planetary wheel carrier 20. The axial stop 54 is rotatable with respect to the planetary wheel carrier 20 and the input shaft 16, and follows the rotation of the ring gear wheel 22. The axial stop 54 secures the ring gear wheel 22 axially and results in an axial bearing of the input shaft 16 being subjected to less tension when the gears 18, 22, 24 are provided with helical teeth. However, instead of or in combination with the thrust stop 54, a pair of thrust bearings 56 can be arranged on both axial surfaces connected to the ring gear wheel 22. Thus, the bearings

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22/28 thrust 56 are arranged between the ring gear wheel and the planetary wheel carrier 20. A second thrust bearing 57 can be arranged between the axis 38 of the sun gear wheel 18 and the planetary wheel carrier 20, for accommodate axial forces generated by the gear wheel sol 18.

[0073] The low gear in gearbox 2 is achieved by displacing the second coupling sleeve 42, so that the gear wheel ring 22 is connected to the transmission housing 12. The axial displacement of the first and second coupling sleeves 42, 43 is provided with a first and second shift forks 60, 61 arranged in an outer circumferential groove 62 in the respective coupling sleeve 42, 43. The first shift fork 60 is influenced by a first actuator 66 and the second shift fork 61 is influenced by a second actuator 67. Each of the first and second actuators 66, 67 can be a pneumatic or hydraulic cylinder. Shift forks 60, 61 and actuators 66, 67 are shown schematically in figure 3.

[0074] Figure 4 schematically illustrates a transmission 3 according to an embodiment of the invention in a low gear position and with the second coupling sleeve 43 in the first position. In this position, the output shaft 28 is disconnected from the planetary gear 14, so that no torque can be transferred from gearbox 2 to output shaft 28, impeller shaft 10 and the drive wheels 8. The second coupling sleeve 43 on this position is only connected to output shaft 28 and not to ring gear wheel 22 or planetary wheel carrier 20. When output shaft 28 is disconnected from planetary gear 14 and clutch 11 is disengaged, so that no torque is transferred to from the internal combustion engine 4 to the gearbox 2, gears can be switched on the gearbox 2.

[0075] Figure 5 schematically illustrates a transmission 3 according to an embodiment of the invention, in a high gear position. When the output shaft 28 was disconnected from the planetary gear and the clutch 11 was disengaged, the first coupling sleeve 42 was moved axially to the second gearing position, in order to disconnect the enPetition box housing 870170027859, from 04/27 / 2017, p. 66/88

23/28 gears 12 of the gear wheel ring 22 and instead connect the gear wheel sol 18 with the planetary wheel carrier 20. Thereafter the second coupling sleeve 43 has been moved axially to its first position, so that the second coupling sleeve 43 transfers the torque from the planetary wheel carrier 20 to the output shaft 28. The torque transmission from the input shaft 16 to the output shaft 28 is in the high gear position through the shaft inlet 16 and the planetary wheel carrier 20, and also to the output shaft 28 through the second coupling sleeve 43, so that the gear ratio through the planetary gear 14 becomes 1: 1. The second axially movable coupling sleeve 43 can, in another gear position, be arranged to engage the ring gear wheel 22 with the output shaft 28. Thus, another gear ratio on the planetary gear is achieved in that position.

[0076] However, since the planetary wheel carrier 20 is in an immobilized position during gear change and the output shaft is rotating due to the rotation of the drive wheels 8, the speed between the planetary wheel carrier 20 and the output shaft 28 must be synchronized before the second coupling sleeve 43 is displaced axially to connect the planetary wheel carrier 20 with the output shaft 28. Therefore, a synchronization element 74 is arranged between the planetary wheel carrier 20 and the output shaft 28. According to an embodiment of the invention, the synchronization element 74 is a friction arrangement, which comprises a first and a second friction surface 76, 78 which can be engaged and disengaged by means of a actuation arrangement 80. Actuation arrangement 80 comprises an electric, pneumatic or hydraulic controlled cylinder 82, where a plunger 84 in cylinder 82 is axially displaceable to engage and disengage the first and second friction surfaces 76, 78. The first friction surface 76 can be arranged on the planetary wheel carrier 20 and the second friction surface 78 can be arranged axially displaceable by the plunger 84. According to the embodiment of figure 5, and also in figures 3 and 4, the first and second friction surfaces 76, 78 can be tapered to increase the

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24/28 frictional force between the friction surfaces 76, 78. According to another embodiment, the cylinder 82 and the plunger 84 can be circular and arranged substantially concentric to the common axis of rotation 30. The second friction surface 78 it is arranged on a circular sleeve 86. The actuation arrangement 80 can be mounted on the gearbox housing 12. For this reason, the actuation arrangement 80 is not rotatable, which simplifies the connection of wires and tubes of fluids to the willingness to act. A radial bearing 90 is arranged between the circular sleeve 86 and the plunger 84, so that the axial displacement of the circular sleeve 86 and the second friction surface 78 can be done without turning the actuator 82 and the plunger 84. The first and second friction surfaces 76, 78 can be tapered to increase the frictional force between friction surfaces 76, 78 and therefore also transfer sufficient torque to accelerate the planetary wheel carrier 20 when synchronizing the speed between the output shaft 28 and the planetary wheel carrier 20.

[0077] Figure 6 schematically illustrates a transmission 3 according to an alternative embodiment of the invention. According to this alternative embodiment, the synchronization element 74 is an electric machine arranged to rotate said planetary wheel carrier 20 when synchronizing the rotation speed between said planetary gear 14 and said at least one driving wheel 8. The synchronization is achieved by activating the electric machine to a speed that rotates said planetary gear 14 with a speed that substantially corresponds to the speed of said output shaft 28 of said second gearbox device 15B.

[0078] An electronic control unit 70 is coupled to gearbox 2, combustion engine 4 and clutch 11 to achieve the upshift. Speed sensors in gearbox 2, main gearbox 6 and internal combustion engine 4 can be connected to control unit 70. A computer 72 can also be connected to control unit 70. Control unit 70 can be a computer with appropriate software for this purpose. The control unit 70 and / or the computer 72 comprises a computer program P, which may include control routines 870170027859, of 27/04/2017, p. 68/88

25/28 release the gearbox 2 of the invention. The program P can be stored in an executable form or in a compressed form in an M memory and / or in a read / write memory. A computer program product can be supplied, which comprises a program code stored in one, by a computer-readable means for executing the upshift, when said program is executed on the control unit 70 or on the computer 72 connected to the control unit 70. Said code may be non-volatile, stored in said computer-readable medium.

[0079] Figure 7 illustrates a flow chart for a method for changing the gear ratio in a gearbox 2 of a vehicle 1 according to a first modality. Gearbox 2 can be configured as described in Figure 2. The method comprises the steps of:

i. - disconnecting said first and second gearbox devices 15A, 15B from said gearbox 2 from said at least one drive wheel 8;

ii. - changing the transmission ratio s102 of said second gearbox device 15A, 15B, 15C when said first and second gearbox devices 15A, 15B of said gearbox 2 are disconnected from said at least one drive wheel 8 ; and iii. - synchronizing s103 the speed of rotation between a rotating element 20, 22 of said second gearbox device 15B and said at least one drive wheel 8, when said gear ratio of said second gearbox device 15B has been changed.

[0080] Before disconnecting said first and second gearbox devices 15A, 15B of said gearbox 2 from said at least one drive wheel 8, the torque of the power source is decreased and the clutch 11 is disengaged .

[0081] If there is a gear arrangement, such as a differential, between the rotating element 20, 22 of said second gearbox device 15B and said at least one drive wheel 8, care must be taken with any

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26/28 gear ratio in such a gear arrangement when synchronizing the speed between the rotating element 20, 22 and said at least one drive wheel 8.

[0082] The step of changing the gear ratio s102 of said second gearbox device 15B when said first and second gearbox devices 15A, 15B of said gearbox 2 are disconnected from said at least one gear wheel. drive 8 can also comprise the steps of:

i. - disconnecting said second gearbox device 15B from said first gearbox device 15A by displacing said first gearbox device 15A to a neutral running position;

ii. - applying a braking force to the rotating element 20, 22 of said second gearbox device 15B by means of a first braking element 212;

iii. - changing the gear ratio s106 of said second gearbox device 15B when said rotating element 20, 22 of said second gearbox device 15B is in an immobilized condition.

[0083] The step of disconnecting said first and second gearbox devices 15A, 15B of said gearbox 2 from said at least one drive wheel 8 further comprises a step of:

i. - disconnect s111 from said planetary gear from said at least one drive wheel 8.

[0084] The step of disconnecting s111 said planetary gear from said at least one driving wheel 8, further comprises a step of:

i. - disconnecting said planetary carrier 20 from said output shaft 28 from said second gearbox device 15B.

[0085] A second axially displaceable coupling sleeve 43 is in a first position arranged to connect said planetary gear 14 to said at least one drive wheel 8 of said vehicle 1 and, in a second position, is arranged to disconnect said planetary gear 14 of said by mePetição 870170027859, of 04/27/2017, p. 70/88

27/28 there is a driving wheel 8 of said vehicle 1, and where in the step of synchronizing s103 the speed of rotation between a rotating element 20, 22 of said second gearbox device 15B and said at least one driving wheel 8 when said gear ratio of said second gearbox device 15B has been changed can further comprise steps of:

i. - synchronize s113 the speed of rotation between said planetary gear 14 and said at least one drive wheel 8 by means of a synchronization element 74 and then ii. - connect s114 of said planetary gear 14 to said at least one drive wheel 8.

[0086] The method also comprises a stage of:

i. - connecting said gearbox 11 to said at least one drive wheel 8, connecting said gearbox 2 to a driving shaft 10 of said vehicle 1.

[0087] After the second gearbox device 15B has been disconnected from the first gearbox device 15A by shifting the first gearbox device 15A to a neutral state, the method further comprises the steps of:

i. - accelerating a rotating element 202 of said first gearbox device 15A by means of said power source 4 after connecting said gearbox 2 to said at least one drive wheel 8, ii. - changing the gear ratio of said first gearbox device 15A by s108 when the rotation speed of said rotation element 201,202 has been accelerated at least to a first speed.

[0088] In steps s107 and s108, a downward shift takes place in the first gearbox device 15A.

[0089] Figure 8 shows a flow chart for a method for changing the gear ratio in a gearbox 2 of a vehicle 1 according to a second modality. Gearbox 2 can be configured as described in Figure 2. Method steps s101 - s106 and s111 - s115 in the first

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28/28 modality are also carried out in the second modality. However, in the second modality the method still comprises the steps of:

i. - applying a braking force only to a rotating component 202 of said first gearbox device 15A by means of a second braking element 211, then connecting said gearbox 2 to at least one drive wheel 8;

[0090] - changing the gear ratio s110 of said first gearbox device 15A when the rotation speed of said rotating component 202 has been reduced at least to a second speed.

[0091] In steps s109 and s110 there is an upward shift in the first gearbox device 15A.

[0092] The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to restrict the invention to the variants described. Many modifications and variations will obviously be evident to one skilled in the art. The modalities were chosen and described in order to better explain the principles of the invention and their practical applications and, thus, enable specialists to understand the invention for various modalities and with the various modifications appropriate for the intended use. The components and aspects specified above can, within the framework of the invention, be combined between the different modalities specified.

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1/6

Claims (15)

1. Method for changing the gear ratio in a vehicle's gearbox (2) (1), said gearbox (2) being arranged to transfer torque between a power source (4) and at least one wheel drive (8) of said vehicle (1), said gearbox (2) comprising a first gearbox device (15A, 15C) and at least a second gearbox device (15B), each of which said first and second gearbox devices (15A, 15B) being individually controllable to engage at least two gears having different gear ratios to form a combined gear ratio of said gearbox (2), said second gearing device gearbox (15B) being arranged between said first gearbox device (15A) and said at least one drive wheel (8), the method characterized by the fact that it comprises the steps of: - disconnecting (s101) said first and second gearbox devices (15A, 15B) from said gearbox (2) from said at least one drive wheel (8); - changing (s102) the gear ratio of said second gearbox device (15B) when said first and second gearbox devices (15A, 15B) of said gearbox (2) are disconnected from said at least one drive wheel (8); and - synchronize (s103) the speed of rotation between a rotation element (20, 22) of said second gearbox device (15B) and said at least one drive wheel (8), when said gear ratio of the said second gearbox device (15B) has been changed. Method according to claim 1, characterized in that the step of changing (s102) the gear ratio of said second gearbox device (15B) when said first and second gearbox devices (15A, 15B ) of said gearbox (2) are disconnected from said at least one drive wheel (8) further comprising the steps of: Petition 870170027859, of 04/27/2017, p. 73/88 2/6 - disconnecting (s104) said second gearbox device (15B) from said first gearbox device (15A) by moving said first gearbox device (15A) to a neutral running position; - applying (s105) a braking force to the rotating element (20, 22) of said second gearbox device (15B) by means of a first braking element (212); - changing (s106) the gear ratio of said second gearbox device (15B) when said rotating element (20, 22) of said second gearbox device (15B) is in an immobilized condition. 3. Method according to claim 2, characterized by the fact that it also comprises the steps of: - accelerating (s107) a rotating element (202) of said first gearbox device (15A) by means of said power source (4) after connecting said gearbox (2) to said at least one drive wheel (8); - changing (s108) the gear ratio of said first gearbox device (15A) when the rotation speed of said rotating element (202) has been accelerated at least to a first speed. 4. Method according to claim 2, characterized by the fact that it also comprises the steps of: - applying (s109) a braking force to a rotating component (202) of said first gearbox device (15A) by means of a second braking element (211), after connecting said gearbox (2) to at least one drive wheel (8); - changing (s110) the gear ratio of said first gearbox device (15A) when the rotation speed of said rotating element (202) has been reduced at least to a second speed. Method according to any of claims 1 to 4, characterized in that said second gearbox device (15B) is an extended gearbox comprising a planetary gear (14), provision 870170027859, of 04/27 / 2017, p. 74/88 3/6 set to provide a high gear and a low gear, where the step of disconnecting (S101) said first and second gearbox devices (15A, 15B) of said gearbox (2) from said at least a drive wheel (8), further comprises a stage of: - disconnect (s111) said planetary gear (14) from said at least one drive wheel (8). Method according to claim 5, characterized in that said planetary gear (14) comprises a sun gear wheel (18) connected to an output shaft (28) of said first gearbox device (15A) and a planetary wheel carrier (20) which carries a plurality of planetary gear wheels (24) which engage said sun gear wheel (18), said planetary wheel carrier (20) being selectively connected to an output shaft (28) said second gearbox device (15B), in which the step of disconnecting (S111) said planetary gear (14) from said at least one drive wheel (8), further comprises a step of: - disconnecting (s112) said planetary wheel carrier (20) from said output shaft (28) from said second gearbox device (15B). Method according to claim 6, characterized in that a second coupling sleeve (43) axially displaceable in a first position is arranged to connect said planetary gear (14) to said at least one drive wheel (8) of said vehicle (1), and in a second position be arranged to disconnect said planetary gear (14) from said at least one drive wheel (8) of said vehicle (1), and in which, in the synchronization step (s103) the speed of rotation between a wheel (20, 22) of said second gearbox device (15B) and at least one drive wheel (8) when said gear ratio of said second gearbox device (15B) has been changed to understand the steps of: - synchronize (s113) the speed of rotation between said planetary gear (14) and said at least one drive wheel (8) by means of a synchronization element, and then Petition 870170027859, of 04/27/2017, p. 75/88 4/6 - connect (s114) said planetary gear (14) to at least one said drive wheel (8). 8. Method according to any one of claims 1 to 7, characterized in that it also comprises a step of: - connecting (s115) said gearbox (2) to said at least one drive wheel (8) connecting said gearbox (2) to an impeller shaft (10) of said vehicle (1). 9. Computer program, characterized by the fact that it comprises a program code that, when said program code is executed on a computer (70, 72), causes that computer (70, 72) to execute the method as defined any of the claims 1 to 8. 10. Computer program product, characterized by the fact that it comprises a computer-readable medium and a computer program as defined in claim 9, in which said computer program is contained in said computer-readable medium. 11. Device for changing the gear ratio in a gearbox (2) of a vehicle (1), said gearbox (2) being arranged to transfer torque between a power supply (4) and at least one gear wheel drive (8) of said vehicle (1), said gearbox (2) comprising a first gearbox device (15A) and at least a second gearbox device (15B), each of said first and second gearbox devices (15A, 15B) being individually controllable to engage at least two gears having different gear ratios to form a combined gear ratio of said gearbox (2), said second gearbox device (15B ) being arranged between said first gearbox device (15A) and said at least one drive wheel (8), the system being characterized by: - means for disconnecting said first and second gearbox devices (15A, 15B) from said gearbox (2) from said at least one drive wheel (8); Petition 870170027859, of 04/27/2017, p. 76/88 5 / Q means for changing the gear ratio of said second gearbox device (15B) when said first and second gearbox devices (15A, 15B) of said gearbox (2) are disconnected from said at least one wheel drive (8); and means for synchronizing the speed of rotation between a rotation element (20, 22) of said second gearbox device (15B) and said at least one drive wheel (8), when said gear ratio of said second gearbox device (15B) has been changed. A system as defined in claim 11, wherein said second gearbox device (15B) is an extended gearbox comprising a planetary gear (14), arranged to provide a high gear and a low gear and for a second axially displaceable coupling sleeve 43) in a first position to be arranged to connect said planetary gear (14) to said at least one drive wheel (8) of said vehicle (1), and in a second position to be arranged to disconnect said gear planetary (14) of at least one drive wheel (8) of said vehicle (1), the system being further characterized by the fact that: - a timing element (74) for synchronizing the speed of rotation between said planetary gear (14) and said at least one driving wheel (8) before connecting said planetary gear (14) to said at least one driving wheel (8). System according to claim 12, characterized in that the synchronization element (74) is a friction arrangement arranged between said planetary wheel carrier (20) and said output shaft (28) of said second gear device of gears (15B): means for synchronizing the rotation speed between said planetary gear (14) and said output shaft (28) of said second gearbox device (15B) engaging the friction clutch. System according to claim 12, in which the synchronization element (74) is an electrical machine arranged to rotate said wheel carrier Petition 870170027859, of 04/27/2017, p. 77/88 Planetary 6/6 (20), with the system still characterized by: - means for synchronizing the speed of rotation between said planetary gear (14) and said at least one drive wheel (8), activating the electric machine up to a speed that rotates said planetary gear (14) with a corresponding speed substantially at the speed of said output shaft (28) of said second gearbox device (15B). 15. Vehicle, characterized by the fact that it comprises a system for changing the gear ratio in a gearbox (2) as defined in claim 11. Petition 870170027859, of 04/27/2017, p. 78/88 1/8