SE539019C2 - Procedure for changing an auxiliary gearbox - Google Patents

Description

BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates to a method of controlling a transmission according to the preamble of claim 1. The invention also relates to a vehicle comprising such a transmission, according to the preamble of claim 8.

For vehicles, and especially for heavier vehicles, for example trucks, an auxiliary gearbox, also called a range gearbox, is often connected to the main gearbox in order to double the number of gear options. Such an auxiliary gearbox usually comprises a planetary gear, which has a low and high gear, respectively, with which the shifting possibilities of the main gearbox can be divided into a low-rank position and a high-rank position. In the low-range mode, a downshift occurs through the planetary gear, and in the high-range mode, the gear ratio is 1: 1 in the planetary gear.

The range gearbox is arranged between the main gearbox and a propeller shaft connected to the drive wheels of the vehicle. The range gearbox is housed in a gearbox housing and comprises an input shaft portion connected to the main gearbox, an output shaft portion and a planetary gear arranged between the input shaft portion and the output shaft portion. The planetary gear usually comprises three components which are rotatably arranged relative to each other, namely a sun gear, a planetary gear holder and a ring gear. With knowledge of the number of teeth of the sun gear and the ring gear, the mutual speeds of the three components can be determined during operation. In a range gearbox, the sun gear may be rotatably connected to the input shaft portion, a plurality of planet gears engaging said sun gear, which planet gears are rotatably mounted on the planetary gear holder rotatably connected to the output shaft portion, and an axially displaceable ring gear enclosing and impeller . The teeth of the sun gear, the planet gears and the ring gear can be obliquely cut, i.e. they have an angle in relation to the axis of rotation common to the sun wheel, the planet gear holder and the ring gear. Alternatively, the sun gear, the planet gears and the ring gear can be provided with straight-foam teeth, i.e. they are substantially parallel to the axis of rotation common to the sun gear, the planet gear holder and the ring gear.

The low and high gears of the gearbox are obtained in a known range gearbox by displacing the ring gear axially between the low range position, in which the ring gear is rotationally locked relative to the gearbox housing, and the high gear position, in which the ring gear is rotatable relative to the gearbox housing. Such a known gearbox comprises two clutch rings arranged on each side of the ring gear, a high clutch ring and a low clutch ring, respectively, and two synchronizing rings, which are arranged on each side of the ring wheel. The task of the synchronizing rings is to achieve a synchronous change. The freedom of movement of the ring wheel in the axial direction is limited by the geometric design of the ring wheel and the clutch ring.

Document WO0155620 discloses a synchronizing device at a planetary gear where the planetary gear comprises a sun gear, a planet gear holder and a ring gear. The sun gear is rotatably connected to the input shaft and a number of planet gears engage with the sun gear, which planet wheels are rotatably mounted on a planet gear holder rotatably connected to an output shaft. An axially displaceable ring gear encloses and engages the planet gears. The low and high gears of the gearbox are obtained by displacing the ring gear axially between the low-range position and the high-range position.

However, these synchronizing devices are subject to wear and tear and involve large repair costs. If the range gearbox is to transmit large torques, synchronizing devices will have considerable dimensions, which entails an increased need for weight and space. When the high-range position is engaged, torque will be transmitted from the sun gear to the plant wheels, which means that facets can form on the gear flanks of the sun gear, which creates noise in the gearbox and accelerates wear of the planetary gear gears.

There are also gearboxes in which the synchronizing devices have been replaced with boomed coupling sleeves. By controlling the transmission so that synchronous speed occurs between the two components to be interconnected, an axial displacement of the coupling sleeve along the two components is made possible in order to connect and interconnect them. When the components are to be disconnected from each other, the transmission is controlled so that a torque balance arises between the components, whereby the coupling sleeve does not transmit torque. It then becomes possible to displace the coupling sleeve along the components in order to disengage them from each other.

Torque balance refers to a condition in which a torque acts on a ring gear arranged at the planetary gear, corresponding to the product of the moment acting on the planetary gear planetary wheel more kindly and the planetary gear ratio while a torque acts on the planetary gear sun gear, corresponding to the torque wheel product and planetary gear ratio). In the event that two of the constituent parts of the planetary gear, sun gear, ring gear or planetary gear holder, are connected by means of a coupling unit, this coupling unit does not transmit torque between the parts of the planetary gear when torque balance prevails. Thus, the coupling unit can be easily displaced and the constituent parts of the planetary gear can be disengaged.

Document US2009 / 0095101, A1 discloses a transmission which includes a main gearbox and a range gearbox. A slidable sleeve is arranged to engage the gearbox in a low-rank position or a high-rank position. The main gearbox comprises an input shaft and a main shaft on which gears can be engaged and disengaged. One or two side axles can be arranged in the main gearbox, one of which can be fitted with a brake device.

SUMMARY OF THE INVENTION Despite known solutions, there is a need to further develop a method for controlling a transmission, where the switching times are short, where the reliability and reliability of the transmission is high, where all components of the transmission are used efficiently.

An object of the invention is to provide a method for controlling a transmission which results in short changeover times.

A further object of the invention is to provide a method for controlling a transmission which results in high reliability and operational reliability of the transmission.

A further object of the invention is to provide a method for controlling a transmission which utilizes all the components included in the transmission efficiently.

These objects are achieved by a method of controlling a transmission of the kind mentioned in the introduction, which is characterized by the features stated in claim 1. These objects are also achieved by a vehicle comprising such a transmission, of the kind mentioned in the introduction, which characterized by the features set forth in claim 8.

Because the second braking device is arranged at the input shaft in order to reduce the speed of the input shaft when shifting in the transmission, synchronous speed or torque balance can be achieved in the auxiliary gearbox in order to change gear position. a traditional auxiliary gearbox, which means that it is quick to switch between different gear positions.

The first and the second coupling sleeve can each be made with a limited wall thickness, which means that the mass of the respective coupling sleeve becomes low. The low mass of the respective coupling sleeve means that it is possible to quickly switch between different gear positions. According to an embodiment of the invention, the drive motor is disconnected from the input shaft by means of the coupling device. Thus, the rotation of the input shaft is not affected by the drive motor, which increases the possibility of quickly and efficiently changing the gear position in the auxiliary gearbox by reducing the speed of the input shaft with the second brake device.

According to an embodiment of the invention, the drive motor is controlled at a constant speed. Thus, an operating condition for the drive motor can be selected during the gear shift, which results in high efficiency and low energy requirements.

According to an embodiment of the invention, the speed of the input shaft is reduced to a speed which is less than the speed of the drive motor. Thus, the drive motor can be driven at a speed that is favorable in terms of efficiency and energy requirements, while the input shaft can be reduced with the second brake device to a speed which is less than the drive motor speed and which allows the gear position to be changed in the auxiliary gearbox.

Additional advantages of the invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, as an example, preferred embodiments of the invention are described with reference to the accompanying drawings, in which: Fig. 1 shows a vehicle in a side view with a gearbox according to the present invention, Fig. 2 shows a schematic sectional view of a transmission according to the present invention in a stored tiger position. Fig. 3 shows a schematic sectional view of the transmission according to the present invention in a high-rank position, and Fig. 4 shows a flow chart regarding a method for controlling 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, for example a truck, which comprises a transmission 3 according to the present invention. The transmission 3 comprises a drive motor 4, a main gearbox 6, a coupling device 5 arranged between the drive motor 4 and the main gearbox 6, an auxiliary gearbox 2 and a propeller shaft 10. The drive 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 further connected to the drive wheel 8 of the vehicle 1 via the PTO shaft 10. The auxiliary gearbox 2 is also called a range gearbox, and has the purpose of doubling the number of gear possibilities. The additional gearbox 2 is surrounded by a gearbox housing 12, Fig. 2 shows a schematic sectional view of a transmission 3 according to the present invention. The main gearbox 6 comprises an input shaft 7 connected to the coupling device 5, a side shaft 9 and a main shaft 26, the input shaft 7 and the main shaft 26 by means of a split gear 11 and a main gear 13, respectively. The pair of gears s1 can be switched on and off the input shaft 7 by means of a first coupling element 15. The pair of gears s2 can be switched on and off the input shaft 7 by means of a second coupling element 17. When both coupling elements 15, 17 disconnect the first and second gear pairs s1, s2 are split 11 moved to a neutral position. The main gear 13 comprises a set of gears g1-g3 where the pair of gears represents a first gear, the pair of gears g2 represents a second gear and the pair of gears g3 represents a third gear. The gear pairs gl - g3 can be switched on and off by means of 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 high gear, respectively, with which the shifting possibilities of the main gearbox 6 can be divided into a low-rank position and a high-rank position. In a first gear position corresponding to the low range position, a downshift occurs through the planetary gear 14. In the second gear position, which corresponds to the high range position, the gear ratio is 1: 1 in the planetary gear 14. Fig. 2 shows the addition gearbox 2 in a second gear position corresponding to the high gear or high range position.

The additional gearbox 2 is housed in the gearbox housing 12 and is connected to the main shaft 26 of the main gearbox 6. The planetary gearbox 14 comprises three main components which are rotatably arranged relative to each other, namely a sun gear 18, a planet gear holder 20 and a ring wheel 22. On the planet gear holder 20 are a number planet gears 24 arranged. Arranged on the planetary gear holder 20 is also the output shaft 28 of the auxiliary gearbox 2, which is coupled to the propeller shaft 10 of the vehicle 1. The sun gear 11 is rotatably connected to the main shaft 26 and the planet gears 24 engage in said sun gear 18, the ring gear 22 encloses and engages the planet gears 24, the teeth 32 of the sun gear 18, the planet gears 24 and the ring gear 22 may be inclined, i.e. they have an angle in relation to a axis of rotation 30 common to the sun gear 18, the planet gear holder 20 and the ring gear 22. By cutting the teeth 32 obliquely, a reaction force is obtained from the gears 18, 22, 24 included in the planet gear 14 in the direction of the axis of rotation 30. The direction of the reaction force depends on the direction in which the teeth 32 in the planetary gear 14 are inclined. Thus, the reaction forces can act backwards or forwards in the extension of the axis of rotation 30.

A first axially displaceable coupling sleeve 40 is in the first gear position arranged to disconnect the main shaft 26 from the planet gear holder 20 and is in the second gear position arranged to connect the main shaft 26 to the planet wheel holder 20. A second axially displaceable coupling sleeve 42 is in the first gear position engaged around the planetary gear 14 surrounding the gearbox housing 12 with the ring gear 22 and in the second gear position arranged to disconnect the gearbox housing 12 from the ring gear 22.

The first axially displaceable coupling sleeve 40 is provided on an inner surface with first booms 44, which are arranged to cooperate with corresponding first booms 44 arranged on the main shaft 26 and the planet wheel holder 20. Corresponding first booms 44 arranged on the main shaft 26 are formed on the periphery of a first ring 46, which is rotatably mounted on the main shaft 26. Corresponding first booms arranged on the planet gear holder 20 are formed on the periphery of a second ring 48, which is rotatably mounted on the planet wheel holder 20.

The second axially displaceable coupling sleeve 42 is provided on an inner surface with second booms 50, which are arranged to cooperate with corresponding second booms 50 arranged on the periphery of the ring wheel 22 and on a projection 52, which is fixedly connected to the gearbox housing 12. Fig. 2 shows a sectional view of the auxiliary gearbox 2 according to the invention in the first gear position or the low range position. The low gear of the auxiliary gearbox 2 is obtained by displacing the first clutch sleeve 40 axially to disengage the planetary gear holder 20 from the main shaft 26 simultaneously, or in close connection with the second clutch sleeve 42 being displaced, so that the ring wheel 22 is coupled to the gearbox housing 12 in Fig. 3. second gear position corresponding to the high gear or high range position. The high gear of the auxiliary gearbox 2 is obtained by displacing the first coupling sleeve 40 to connect the main shaft 26 to the planet gear holder 20. The second coupling sleeve 42 is displaced to disengage the ring wheel 22 from the gearbox housing 12. The second coupling sleeve 42 will thus only be connected to the housing 12 the second clutch sleeve 42 becomes stationary and will not affect mass inertia forces during the rotation of the ring gear 22. The torque transmission from the main shaft 26 to the output shaft 28 thus takes place via the main shaft 26 and the planet gear holder 20 and further to the output shaft 28. becomes 1: 1.

The axial displacement of the first and second coupling sleeves 40, 42 is effected by a first and second gear forks 58, 60, which are arranged in a circumferential groove 62 on the outside of the first and second coupling sleeves 40, 42. The first gear fork 58 is actuated by a first power member 64 and the second shift fork 60 are actuated by a second power member 66. The first and second power members 64, 66 may be a pneumatic or hydraulic cylinder. The first and second shift forks 58, 60 and the first and second power members 64, 66 are schematically drawn in Fig. 2.

Preferably, the respective coupling sleeve 40, 42 has a small mass, which means that low energy and force are required to move the respective coupling sleeve 40, 42 when changing. Thus, a rapid changeover for a short period of time can be performed between the different gear positions in the additional gearbox 2.

By moving the first clutch sleeve to a position when it is only engaged with the main shaft or planetary gear holder while the second clutch sleeve is moved to a position when it is only engaged with the gearbox housing, the additional gearbox will be shifted to a neutral position in which no torque transmission occurs through the auxiliary gearshift.

A first braking device 54 is arranged at the side shaft 9 to reduce the speed of the side shaft 9 when shifting in the transmission 3 and a second braking device 56 is arranged at the input shaft 7 to reduce the speed of the input shaft 7 when shifting in the transmission 3. Because the second brake device 56 is arranged at the input shaft 7 in order to reduce the speed of the input shaft 7 when shifting in the transmission 3, synchronous speed or torque balance can be achieved in the auxiliary gearbox 2 in order to change gear position. The first and second brake devices 54, 56 can each consist of friction brakes, which are controlled hydraulically, pneumatically and / or electrically. The transmission 3 according to the invention operates as follows when shifting from the first to the second gear position, i.e. In the Fig. 2, the drive motor 4 has been controlled to a constant speed and an operating condition which is advantageous from an energy point of view. If the drive motor 4 is an internal combustion engine, the fuel consumption will be minimal at the constant speed. The coupling device 5 has been controlled to a disengaged position, which means that the drive motor 4 and the input shaft 7 are no longer interconnected and no torque is transmitted between them. By slowing down the speed of the input shaft 7 with the first and second brake devices 54, 56, torque balance can be created between the ring gear 22 and the gearbox housing 12. When torque balance prevails between the ring gear 22 and the gearbox housing 12, the auxiliary gearbox 2 is moved to a neutral position by the second clutch sleeve 42 is displaced axially to disengage the ring gear 22 from the gearbox housing 12.1 in the neutral position, no torque is transmitted through the auxiliary gearbox 2.

To load the high gear in the auxiliary gearbox 2, the speed of the input shaft 7 is increased by connecting the input shaft 7 to the drive motor 4 for a predetermined time by means of the drive motor 5, which causes the speed of the side shaft 9 and the main shaft 26 to increase. When a synchronous speed is reached between the main shaft 26 and the planet gear holder 20, the gear position in the auxiliary gearbox 2 is changed to the high gear by displacing the first clutch sleeve 40, so that the main shaft 26 is coupled to the planetary gear holder 20. Thus, a new gear position in the auxiliary gearbox 2 has

By designing the coupling device 5 as a friction coupling, a slippage effect can be generated when the input shaft 7 is coupled to the drive motor 4 by means of the coupling device 5 for a predetermined time. In the event that the speed of the input shaft 7 and the side shaft 9 becomes too high when the input shaft 7 is coupled to the drive motor 4 by means of the coupling device 5 during the predetermined time, the speed can be reduced to the desired speed by the first and / or second brake device 54, 56 The gear pairs g1-g3 of the main gear 13 are moved to a neutral position by disengaging the gear pairs g1-g3 from the main shaft 26 by means of the third, fourth and fifth coupling elements 16, 21, 23. This has been made possible by the main shaft 26 being in torque balance with the respective gear pairs gl -g3, which are arranged on the main shaft 26. Thus, no torque is transmitted from the main shaft 26 to the respective gear pairs g1-g3.

The split gear 11 is moved to a neutral position by the first and second clutch elements 15, 17 being disengaged from the respective gear pairs si, s2. This is made possible by bringing the input shaft 7 into torque balance with the respective gear pairs s1, s2, which are arranged on the input shaft 7, no torque being transmitted from the input shaft 7 to the respective gear pairs s1, s2.

To engage a gear in the main gear 13, the speed of the input shaft 7 is increased by coupling the input shaft 7 to the drive motor 4 for a predetermined time by means of the clutch device 5, which causes the speed of the side shaft 9 to increase, which in turn increases the g-g3 speed. When a synchronous speed has been reached between the main shaft 26 and the gear pair gl-g3 to be coupled to the main shaft 26, the appropriate gear pair gl-g3 is coupled to the main shaft 26 by means of any of the third, fourth or fifth coupling elements 19, 21, 23. new gear position in the main gear 13 engaged.

Finally, the clutch device 5 is activated, so that the drive motor 4 is connected to the main gearbox 6, after which the drive motor 4 accelerates the input shaft to one with that of the respective gear pairs s1, s2 of the split gear 11 which was not previously connected to the input shaft 7, but which is now is coupled to the input shaft 7. When synchronous speed has been achieved, it is coupled by the respective gear pairs s1, s2 which are to be coupled to the input shaft 7 by means of the first or the second coupling element 15, 17. Thus, a new gear position in the split gear 11 has been engaged.

The new gear positions in the main gearbox 6 and the additional gearbox 2 are shown schematically in Fig. 3.

It should be mentioned in this context that the input shaft 7 and the main shaft 26 can be connected in order to obtain a direct gear through the main gearbox 6.1. the input shaft 7 and the main shaft 26. In this direct gear position no torque is transmitted via the side shaft 9. The direct coupling between the input shaft 7 and the main shaft 26 takes place via the second coupling element 17 or the third coupling element 19. When the second coupling element 17 is disengaged with the gear pair s2 it can be displaced axially and engage the main shaft 26 to transmit torque between the input shaft 7 and the main shaft 26. Alternatively, when the third coupling element 19 is disengaged from the gear pair g I, it can be displaced axially and engage the input shaft 7 to transmit torque between the input shaft 7 and the head 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 position, so that the side shaft 9 is caused to rotate by the gear 11 or 13 which is engaged, but without the side shaft transmitting torque between the input the 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 side shaft 9 becomes stationary.

Fig. 4 shows a flow chart relating to a method for controlling the transmission 3 according to the present invention. The method comprises the steps of: a) reducing the speed of the input shaft 7 with a second brake device 56, which is arranged at the input shaft 7, b) reducing the speed of the side shaft 9 with the first brake device 54, and c) changing the gear position in the auxiliary gearbox 2 to a second gear position, in which the main shaft 26 is coupled to the planetary gear holder 20, Before step a), the drive motor 4 is preferably disconnected from the input shaft 7 by means of the coupling device 5 in a step d).

After step d) and before step a), the drive motor 4 is preferably controlled to a constant speed in a step e).

After step b) and before step c), the speed of the input shaft 7 is preferably increased by connecting the input shaft 7 to the drive motor 4 by means of the coupling device 5 in a step f), for a predetermined time.

After step f) and before step c), the gear position in the main gear 13 in a step g) is preferably changed.

After step c), preferably change gear position in the split gear 11 in a step h).

After step c) and before step h), the drive motor 4 is preferably coupled to the input shaft 7 by means of the coupling device 5 in a step i).

An electronic control unit 70 is connected to the kit gearbox 2, the main gearbox 6, the drive motor 4 and the clutch 68 for performing the above gear steps. Preferably, a number of speed sensors (not shown) in the auxiliary gearbox 2, the main gearbox 6 and the drive motor 4 may be connected to the control unit 70. Another computer 72 may also be connected to the control unit 70. The control unit 70 may be a computer with suitable software for this purpose. The control unit 70 and / or the computer 72 comprises a computer program P, which may comprise routines for controlling the auxiliary gearbox 2 according to the present invention. The program P can be stored in an executable manner or in a compressed manner in a memory M and / or in a read / write memory. Preferably, a computer program product is provided, which comprises a program code stored on a computer readable medium for performing the switching steps above, when said program code is run on the control unit 70 or another computer 72 connected to the control unit 70. Said program code may be non-volatile stored on mentioned by a computer readable medium.

The stated components and features stated above can be combined within the scope of the invention between different specified embodiments.

Claims (4)

A method of shifting in a transmission (3) for vehicles comprising a drive motor (4), which transmission comprises a main gearbox (6), an auxiliary gearbox (2) and a coupling device arranged between the drive motor (4) and the main gearbox (6). (5), which main gearbox (6) comprises an input shaft (7) connected to the coupling device (5), a side shaft (9) and a main shaft (26), which side shaft (9) is connected to the input shaft (7) and the main shaft (26) by means of 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 gear (18) and a planet gear holder (20), on which at least one planet gear (24) is rotatably mounted, which ring gear (22) and sun gear (18) engage the at least one planet gear (24) by means of teeth (32), the planetary gear (14) being connected to the main shaft (26) of the main gearbox (6). ), and wherein a first braking device (54) is arranged at the side shaft (9) so that when shifting in the transmission (3) reducing the speed of the side shaft (9), characterized in that the method comprises the steps of: a) reducing the speed of the input shaft (7) with a second braking device (56) arranged at the input shaft (7), b ) reducing the speed of the side axle (9) with the first brake device (54), and c) changing the gear position in the auxiliary gearbox (2) to a second gear position, in which the main axle (26) is coupled to the planetary gear holder (20). Method according to claim 1, characterized in that before step a): d) disconnect the drive motor (4) from the input shaft (7) by means of the coupling device (5). Method according to claim 2, characterized in that after step d) and before step a): e) steers the drive motor (4) to a constant speed. Method according to one of Claims 2 to 3, characterized in that after step b) and before step c): step f) increases the speed of the input shaft (7) by coupling the input shaft (7) to the drive motor for a predetermined time. (4) by means of the cup device (5), and after step f) and before step c): g) change gear position in the main gear (13), 5, Method according to any one of claims 1 - 4, characterized in that after step c) : h) change gear ownership in the split gear (11). Method according to claim 5, characterized in that after step c) and before step h): i) coupling the drive motor (4) to the input shaft (7) by means of the coupling device (5). Vehicle (1), characterized in that it comprises a transmission (3), which is switched according to any one of claims 1-6, 8, Computer program (P) for controlling a transmission (3), wherein said computer program (P) comprises program code for causing an electronic control unit (48) or another computer (53) connected to the electronic control unit (48) to perform the steps according to any one of claims 1-6. A computer program product comprising a program code stored on a computer readable medium for performing the method steps according to any one of claims 1-6, when said program code is executed on an electronic control unit (48) or another computer (53) connected to the electronic the control unit (48).