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Patent Searching and Data


Title:
A TRANSMISSION ASSEMBLY
Document Type and Number:
WIPO Patent Application WO/2018/171894
Kind Code:
A1
Abstract:
The present invention relates to a transmission assembly (48) comprising an input shaft (64) and an output shaft (66). The transmission assembly (48) comprises a planetary gear assembly (68) which in turn comprises a ring gear (70), a first and a second sun gear (72, 74) and a planet gear connecting assembly connecting the ring gear (70) to each one of the first and second sun gear (72, 74). The planet gear connecting assembly (76) comprises a radially outward planet gear (78) and a radially inward planet gear (80) meshing with the radially outward planet gear (78). The radially outward planet gear (78) and the radially inward planet gear (80) are connected to one another via a common planet carrier (82). The input shaft (64) is connected to the common planet carrier (82). The first sun gear (72) meshes with the radially outward planet gear (78) and the second sun gear (74) meshes with the radially inward planet gear (80). Each one of the second sun gear (74) and the ring gear (70) is selectively and individually connectable to the output shaft (66).

Inventors:
ÅKERBLOM MATS (SE)
HEIKINNIEMI ANNIKA (SE)
Application Number:
PCT/EP2017/057070
Publication Date:
September 27, 2018
Filing Date:
March 24, 2017
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
VOLVO TRUCK CORP (SE)
International Classes:
F16H3/66; B60K17/346
Foreign References:
EP0684153A11995-11-29
US20120100952A12012-04-26
US20030119619A12003-06-26
US4722246A1988-02-02
DE2743583A11979-04-05
Attorney, Agent or Firm:
VOLVO TECHNOLOGY CORPORATION (SE)
Download PDF:
Claims:
CLAIMS

1 . A transmission assembly (48) comprising an input shaft (64) and an output shaft (66), said transmission assembly (48) comprising a planetary gear assembly (68) which in turn comprises a ring gear (70), a first and a second sun gear (72, 74), and a planet gear connecting assembly connecting said ring gear (70) to each one of said first and second sun gear (72, 74), said planet gear connecting assembly (76) comprising a radially outward planet gear (78) and a radially inward planet gear (80) meshing with said radially outward planet gear (78), said radially outward planet gear (78) and said radially inward planet gear (80) being connected to one another via a common planet carrier (82), said input shaft (64) being connected to said common planet carrier (82), said first sun gear (72) meshing with said radially outward planet gear (78) and said second sun gear (74) meshing with said radially inward planet gear (80), each one of said second sun gear (74) and said ring gear (70) being selectively and individually connectable to said output shaft (66).

2. The transmission assembly (48) according to claim 1 , further comprising a

connecting mechanism (84) for the second sun gear (74), said second sun gear (74) connecting mechanism (84) being adapted to assume an engaged condition in which said second sun gear (74) is operatively connected to said output shaft (66) and a disengaged condition in which said second sun gear (74) is not operatively connected to said output shaft (66).

3. The transmission assembly (48) according to claim 2, wherein said second sun gear (74) connecting mechanism (84) comprises at least one of: a friction clutch, a dog clutch and a one-way clutch.

4. The transmission assembly (48) according to any one of the preceding claims, further comprising a connecting mechanism (86) for the ring gear (70), said ring gear (70) connecting mechanism (86) being adapted to assume an engaged condition in which said ring gear (70) is operatively connected to said output shaft (66) and a disengaged condition in which said ring gear (70) is not operatively connected to said output shaft (66).

The transmission assembly (48) according to claim 4, wherein said ring gear (70) connecting mechanism (86) comprises at least one of: a friction clutch, a dog clutch and a one-way clutch.

The transmission assembly (48) according to any one of the preceding claims, further comprising an additional output shaft (88), said additional output shaft (88) being connected to said first sun gear (72).

A driveline (42) for a vehicle (10), preferably a working machine, said driveline (84) comprising a power source (44), at least one front axle (16), at least one rear axle (26) and a transmission assembly (48) according to claim 6, said power source (44) being connected to said input shaft (64), said at least one front axle (16) being connected to one of said output shaft (66) and said additional output shaft (88), said at least one rear axle (26) being connected to the other one of said one of said output shaft (66) and said additional output shaft (88).

The driveline (42) according to claim 7, wherein said at least one front axle (16) is connected to said additional output shaft (88) and said at least one rear axle (26) is connected to the output shaft (66).

A vehicle (10), preferably a working machine, comprising a transmission assembly (48) according to any one of claims 1 - 6 and/or a driveline (42) according to claim 7 or claim 8.

10. A method for operating a driveline (42) for a vehicle (10), preferably a working machine, said driveline (42) comprising a power source (44), at least one front axle (16), at least one rear axle (26) and a transmission assembly (48) operatively connecting said power source (44) to each one of said at least one front axle (16) and said at least one rear axle (26), wherein said transmission assembly (48) comprises an input shaft (64), an output shaft (66) and an additional output shaft (88), said power source (44) being operably connected to said input shaft (64), said at least one front axle (16) being connected to one of said output shaft (66) and said additional output shaft (88), said at least one rear axle (26) being connected to the other one of said one of said output shaft (66) and said additional output shaft (88), said transmission assembly (48) comprising a planetary gear assembly (68, 100) which in turn comprises a ring gear (70; 102), a first and a second sun gear (72, 74; 108, 1 10), and a planet gear connecting assembly (76) connecting said ring gear (70; 102) to each one of said first and second sun gear (72, 74; 108, 1 10), one of said ring gear (70; 102), said first sun gear (72; 108 ) and said second sun gear (74; 1 10) constituting a first torque transferring component adapted to be selectively and individually connectable to said output shaft (66), one of said ring gear (70; 102), said first sun gear (72; 108) and said second sun gear (74; 1 10) constituting a second torque transferring component adapted to be selectively and individually connectable to said output shaft (66), said first and second torque transferring components being different, said transmission assembly (48) being controllable so as to provide a first torque distribution between said at least one front axle (16) and said at least one rear axle (26, 28) by connecting said first torque transferring component to said output shaft (66) and disconnecting said second torque transferring component from said output shaft (66), said transmission assembly (48) being controllable so as to provide a second torque distribution between said at least one front axle (16) and said at least one rear axle (26) by connecting said second torque transferring component to said output shaft (66) and disconnecting said first torque transferring component from said output shaft (66), said method comprising: detecting a load condition of said vehicle (10) and controlling said transmission assembly (48) so as to assume one of said first torque distribution and said second torque distribution in response to said detected load condition.

1 1 . The method according to claim 10, wherein said first torque distribution results in a first torque portion imparted on said at least one rear axle (26) and wherein said second torque distribution results in a second torque portion imparted on said at least one rear axle (26), said first torque portion being greater than said second torque portion, said method comprising:

- upon detection that said vehicle (10) is in a loaded condition, controlling said transmission assembly (48) such that said first torque distribution is obtained.

12. The method according to claim 1 1 , further comprising:

- upon detection that said vehicle (10) is in an unloaded condition, controlling said transmission assembly (48) such that said second torque distribution is obtained.

13. The method according to any one of claims 10 to 12, wherein said first torque transferring component is constituted by one of said ring gear (70) and said first sun gear (108), preferably by said ring gear (70). 14. The method according to any one of claims 10 to 13, wherein said second torque transferring component is constituted by said second sun gear (74; 1 10).

15. The method according to any one of claims 10 to 14, wherein said planet gear connecting assembly (76) comprises a radially outward planet gear (78) and a radially inward planet gear (80) meshing with said radially outward planet gear (78), said radially outward planet gear (78) and said radially inward planet gear (80) being connected to one another via a common planet carrier (82), said input shaft (64) being connected to said common planet carrier (82), said first sun gear (72) meshing with said radially outward planet gear (78) and said second sun gear (74) meshing with said radially inward planet gear (80), said method comprising: - obtaining said first torque distribution between said at least one front axle (16) and said at least one rear axle (26) by arranging said second sun gear (74) disconnected from said output shaft (66) and arranging said ring gear (70) connected to said output shaft (66).

16. The method according to claim 15, further comprising:

- obtaining said second torque distribution between said at least one front axle (16) and said at least one rear axle (26) by arranging said second sun gear (74) connected to said output shaft (66) and arranging said ring gear (70) disconnected from said output shaft (66).

17. The method according to any one of claims 10 to 16, further comprising:

- obtaining a locked-up condition between said at least one front axle (16) and said at least one rear axle (26) by arranging said first torque transferring component connected to said output shaft (66) and also arranging said second torque transferring component connected to said output shaft (66).

8. The method according to any one of claims 10 to 17, wherein said at least one front axle (16) is connected to said additional output shaft (88) and said at least one rear axle (26) is connected to said output shaft (66).

9. A computer program comprising program code means for performing the steps of any of claims 10 - 18 when said program is run on a computer.

20. A computer readable medium carrying a computer program comprising program code means for performing the steps of any of claims 10 - 18 when said program product is run on a computer.

21 . A control unit (94) for operating a driveline (42) for a vehicle (10), preferably a working machine, said driveline (42) comprising a power source (44), at least one front axle (16), at least one rear axle (26) and a transmission assembly (48) operatively connecting said power source (44) to each one of said at least one front axle (16) and said at least one rear axle (26), wherein said transmission assembly (48) comprises an input shaft (64), an output shaft (66) and an additional output shaft (88), said power source (44) being operably connected to said input shaft (64), said at least one front axle (16) being connected to one of said output shaft (66) and said additional output shaft (88), said at least one rear axle (26) being connected to the other one of said one of said output shaft (66) and said additional output shaft (88), said transmission assembly (48) comprising a planetary gear assembly (68, 100) which in turn comprises a ring gear (70; 102), a first and a second sun gear (72, 74; 108, 1 10), and a planet gear connecting assembly (76) connecting said ring gear (70; 102) to each one of said first and second sun gear (72, 74; 108, 1 10), one of said ring gear (70; 102), said first sun gear (72; 108) and said second sun gear (74; 1 10) constituting a first torque transferring component adapted to be selectively and individually connectable to said output shaft (66), one of said ring gear (70; 102), said first sun gear (72; 108) and said second sun gear (74; 1 10) constituting a second torque transferring component adapted to be selectively and individually connectable to said output shaft (66), said first and second torque transferring components being different, said transmission assembly (48) being controllable so as to provide a first torque distribution between said at least one front axle and said at least one rear axle by connecting said first torque transferring component to said output shaft (66) and disconnecting said second torque transferring component from said output shaft (66), said transmission assembly (48) being controllable so as to provide a second torque distribution between said at least one front axle and said at least one rear axle by connecting said second torque transferring component to said output shaft (66) and disconnecting said first torque transferring component from said output shaft (66), said control unit (94) being adapted to receive a load condition signal indicative of a load condition of said vehicle (10), said control unit further being adapted to issue a control signal to said transmission assembly (48) so as to assume one of said first torque distribution and said second torque distribution in response to said load condition signal.

Description:
A transmission assembly

TECHNICAL FIELD

The invention relates to a transmission assembly according to the preamble of claim 1 . Moreover, the invention relates to each one of a method for operating a driveline for a vehicle, a computer program, a computer readable medium and a control unit.

The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described with respect to an articulated hauler, the invention is not restricted to this particular vehicle, but may also be used in other vehicles such as wheel loader, a backhoe loader or a truck.

BACKGROUND

In various types of vehicles, which are propelled by at least two wheel axes, it may be desired to have a longitudinal differential between the two wheel axes in order to distribute torque therebetween. As an example, US 2014/0039767 A1 discloses a machine in which torque can be distributed between front and rear wheels in dependence of a weight distribution of the machine.

However, it would be desirable to further improve the means for distributing torque between at least two driving axes of a vehicle. Moreover, it would be desirable to obtain a transmission device that can alter the torque transmission therethrough in a cost-efficient manner.

SUMMARY

An object of the invention is to provide a device for obtaining a gear change between an input shaft and an output shaft of the device, which device can alter the torque transmission between the two shafts in a desired manner.

The object is achieved by a transmission assembly according to claim 1 .

As such, the present invention relates to transmission assembly comprising an input shaft and an output shaft. The transmission assembly comprises a planetary gear assembly which in turn comprises a ring gear, a first and a second sun gear, and a planet gear connecting assembly connecting the ring gear to each one of the first and second sun gear. The planet gear connecting assembly comprises a radially outward planet gear and a radially inward planet gear meshing with the radially outward planet gear. The radially outward planet gear and the radially inward planet gear are connected to one another via a common planet carrier. The input shaft is connected to the common planet carrier. The first sun gear meshes with the radially outward planet gear and the second sun gear meshes with the radially inward planet gear. Each one of the second sun gear and the ring gear is selectively and individually connectable to the output shaft. The above transmission assembly implies that at least two different torque transmission levels between the input shaft and the output shaft can be obtained in a cost-efficient manner. Moreover, by virtue of the fact that each one of the first and second planet gear sets is connected to a common planet carrier as well to the ring gear, a relatively compact transmission assembly may be obtained.

Optionally, the transmission assembly further comprises a connecting mechanism for the second sun gear. The second sun gear connecting mechanism is adapted to assume an engaged condition in which the second sun gear is operatively connected to the output shaft and a disengaged condition in which the second sun gear is not operatively connected to the output shaft. The connecting mechanism for the second sun gear implies that the connection or disconnection of the second sun gear to the output shaft may be obtained in a straightforward manner.

Optionally, the second sun gear connecting mechanism comprises at least one of: a friction clutch, a dog clutch and a one-way clutch.

Optionally, the transmission assembly further comprises a connecting mechanism for the ring gear. The ring gear connecting mechanism is adapted to assume an engaged condition in which the ring gear is operatively connected to the output shaft and a disengaged condition in which the ring gear is not operatively connected to the output shaft.

Optionally, the ring gear connecting mechanism comprises at least one of: a friction clutch, a dog clutch and a one-way clutch. Optionally, the transmission assembly further comprises an additional output shaft. The additional output shaft is connected to the first sun gear. By virtue of the fact that the additional output shaft is connected to the first sun gear, the transmission assembly can be used for distributing torque between the output shaft and the additional output shaft. Such a capability may for instance be desired when distributing torque between two driving axles of a vehicle.

A second aspect of the present invention relates to a driveline for a vehicle, preferably a working machine. The driveline comprises a power source, at least one front axle, at least one rear axle and a transmission assembly according to the first aspect of the present invention. The power source is connected to the input shaft. The at least one front axle is connected to one of the output shaft and the additional output shaft. The at least one rear axle is connected to the other one of the one of the output shaft and the additional output shaft.

Optionally, the at least one front axle is connected to the additional output shaft and the at least one rear axle is connected to the output shaft.

A third aspect of the present invention relates to a vehicle, preferably a working machine, comprising a transmission assembly according to the first aspect of the present invention and/or a driveline according to the second aspect of the present invention.

A fourth aspect of the present invention relates to a method for operating a driveline for a vehicle, preferably a working machine. The driveline comprises a power source, at least one front axle, at least one rear axle and a transmission assembly operatively connecting the power source to each one of the at least one front axle and the at least one rear axle.

The transmission assembly comprises an input shaft, an output shaft, and an additional output shaft. The power source is operably connected to the input shaft, the at least one front axle is connected to one of the output shaft and the additional output shaft and the at least one rear axle is connected to the other one of the one of the output shaft and the additional output shaft. The transmission assembly comprises a planetary gear assembly which in turn comprises a ring gear, a first and a second sun gear, and a planet gear connecting assembly connecting the ring gear to each one of the first and second sun gear. One of the ring gear, the first sun gear and the second sun gear constitutes a first torque transferring component adapted to be selectively and individually connectable to the output shaft. Moreover, one of the ring gear, the first sun gear and the second sun gear constitutes a second torque transferring component adapted to be selectively and individually connectable to the output shaft. The first and second torque transferring components are different.

The transmission assembly is controllable so as to provide a first torque distribution between the at least one front axle and the at least one rear axle by connecting the first torque transferring component to the output shaft and disconnecting the second torque transferring component from the output shaft. Further, the transmission assembly is controllable so as to provide a second torque distribution between the at least one front axle and the at least one rear axle by connecting the second torque transferring component to the output shaft and disconnecting the first torque transferring component from the output shaft

The method according to the fourth aspect of the present invention comprises detecting a load condition of the vehicle and controlling the transmission assembly so as to assume one of the first torque distribution and the second torque distribution in response to the detected load condition.

Traditionally employed methods for obtaining a desired load distribution may involve a step of braking components of a planetary gear assembly. Such component braking generally results in energy losses and/or requires an accurate braking control in order to arrive at the desired torque distribution. The method according to the fourth aspect of the present invention, which proposes that the first or second torque distribution is selectively obtained by connecting a torque transferring component to the output shaft and disconnecting another torque transferring component from the output shaft, is generally not related to large energy losses, owing to the fact that components are either operatively connected to the output shaft or not. Moreover, since the first and second torque distributions are obtained by connecting or disconnecting components to the output shaft, the control of the transmission assembly so as to assume one of the first and second torque distributions may be performed in a straightforward manner not necessarily requiring a precise control of actuators or the like. Optionally, the first torque distribution results in a first torque portion imparted on the at least one rear axle and wherein the second torque distribution results in a second torque portion imparted on the at least one rear axle. The first torque portion is greater than the second torque portion and the method comprises upon detection that the vehicle is in a loaded condition, controlling the transmission assembly such that the first torque distribution is obtained.

Optionally, the method further comprises:

- upon detection that the vehicle is in an unloaded condition, controlling the transmission assembly such that the second torque distribution is obtained.

Optionally, the first torque transferring component is constituted by one of the ring gear and the first sun gear, preferably by the ring gear.

Optionally, the second torque transferring component is constituted by the second sun gear.

Optionally, the planet gear connecting assembly comprises a radially outward planet gear and a radially inward planet gear meshing with the radially outward planet gear. The radially outward planet gear and the radially inward planet gear are connected to one another via a common planet carrier. The input shaft is connected to the common planet carrier. The first sun gear meshes with the radially outward planet gear and the second sun gear meshing with the radially inward planet gear. The method comprises:

- obtaining the first torque distribution between the at least one front axle and the at least one rear axle by arranging the second sun gear disconnected from the output shaft and arranging the ring gear connected to the output shaft.

Optionally, the method further comprises:

- obtaining the second torque distribution between the at least one front axle and the at least one rear axle by arranging the second sun gear connected to the output shaft and arranging the ring gear disconnected from the output shaft.

Optionally, the method further comprises: - obtaining a locked-up condition between the at least one front axle and the at least one rear axle by arranging the first torque transferring component connected to the output shaft and also arranging the second torque transferring component connected to the output shaft.

Optionally, the at least one front axle is connected to the additional output shaft and the at least one rear axle is connected to the output shaft.

A fifth aspect of the present invention relates to a computer program comprising program code means for performing the steps of the fourth aspect of the present invention when the program is run on a computer.

A sixth aspect of the present invention relates to a computer readable medium carrying a computer program comprising program code means for performing the steps of the fourth aspect of the present invention when the program product is run on a computer.

A seventh aspect of the present invention relates to a control unit for operating a driveline for a vehicle, preferably a working machine. The driveline comprises a power source, at least one front axle, at least one rear axle and a transmission assembly operatively connecting the power source to each one of the at least one front axle and the at least one rear axle.

The transmission assembly comprises an input shaft, an output shaft, and an additional output shaft. The power source is operably connected to the input shaft, the at least one front axle being connected to one of the output shaft and the additional output shaft and the at least one rear axle being connected to the other one of the one of the output shaft and the additional output shaft.

The transmission assembly comprises a planetary gear assembly which in turn comprises a ring gear, a first and a second sun gear, and a planet gear connecting assembly connecting the ring gear to each one of the first and second sun gear.

One of the ring gear, the first sun gear and the second sun gear constitutes a first torque transferring component adapted to be selectively and individually connectable to the output shaft. One of the ring gear, the first sun gear and the second sun gear constitutes a second torque transferring component adapted to be selectively and individually connectable to the output shaft. The first and second torque transferring components are different. The transmission assembly is controllable so as to provide a first torque distribution between the at least one front axle and the at least one rear axle by connecting the first torque transferring component to the output shaft and disconnecting the second torque transferring component from the output shaft. Moreover, the transmission assembly is controllable so as to provide a second torque distribution between the at least one front axle and the at least one rear axle by connecting the second torque transferring component to the output shaft and disconnecting the first torque transferring component from the output shaft.

The control unit is adapted to receive a load condition signal indicative of a load condition of the vehicle. The control unit further is adapted to issue a control signal to the transmission assembly so as to assume one of the first torque distribution and the second torque distribution in response to the load condition signal.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

In the drawings:

Fig. 1 is a side view of an articulated hauler;

Fig. 2 schematically illustrates a driveline for the Fig. 1 articulated hauler; Fig. 3 schematically illustrates an embodiment of a transmission assembly; Fig. 4 schematically illustrates a portion of the Fig. 3 transmission assembly; Fig. 5 schematically illustrates another embodiment of a transmission assembly; Fig. 6 schematically illustrates a further embodiment of a transmission assembly;

5

Fig. 7 schematically illustrates a portion of the Fig. 6 transmission assembly, and

Fig. 8 is a flow chart illustrating a method according to the present invention.

10 DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Fig. 1 illustrates a side view of a vehicle 10 which is exemplified as a working machine. In particular, the Fig. 1 vehicle is exemplified as a frame-steered articulated hauler, also called dumper.

15

As may be gleaned from Fig. 1 , the vehicle 10 illustrated therein comprises a front vehicle section 12 comprising a front frame 14 and a front axle 16. The front axle 16 is in turn connected to one or more front ground engagement elements 18 adapted to propel the vehicle 10. In the Fig. 1 example, the one or more front ground engagement elements 18 20 is exemplified as a pair of front wheels, although only the left front wheel is visible in the Fig. 1 view. Fig. 1 further illustrates that the front vehicle section 12 comprises a cab 20 for a driver.

Moreover, as may be gleaned from Fig. 1 , the vehicle 10 comprises a rear vehicle section 25 22 comprising a rear frame 24, a front rear axle 26 and a back rear axle 28. The front rear axle 26 is connected to one or more front rear ground engagement elements 30. Moreover, the back rear axle 28 is connected to one or more back rear ground engagement elements 32. In the Fig. 1 embodiment, the one or more front rear ground engagement elements 30 is exemplified as a pair of wheels. In a similar vein, the one or 30 more back rear ground engagement elements 32 is exemplified as a pair of wheels.

Although the Fig. 1 embodiment of the vehicle 10 comprises two rear wheel axles 26, 28, it is also envisaged that embodiments of the vehicle may be equipped with only one rear axle (not shown). Furthermore, although the Fig. 1 embodiment exemplifies each one of 35 the ground engagement elements 18, 30, 32 as a wheel, it is also contemplated that in embodiments of the vehicle 10, one or more of the ground engagement elements 18, 30, 32 may comprise crawlers (not shown) or any other type of means for ground engagement.

5 The front frame 14 is connected to the rear frame 24 via a first rotary joint 34 which allows the front frame 14 and the rear frame 22 to be rotated relative to one another about a vertical axis 36 for steering (turning) the vehicle 10. A pair of hydraulic cylinders 38 is arranged on respective sides of the rotary joint 34 for steering the vehicle 10. The hydraulic cylinders are controllable by the driver of the vehicle via a wheel and/or a 10 joystick (not shown).

A second rotary joint 40 is provided in order to allow the front frame 14 and the rear frame 24 to be rotated relative to one another about an imaginary longitudinal axis, that is to say an axis which extends in the longitudinal direction of the vehicle 10.

15

In order to propel the Fig. 1 vehicle 10, the vehicle 10 comprises a driveline. To this end, reference is made to Fig. 2 illustrating an embodiment of a driveline 42 for a vehicle, preferably a working machine. The Fig. 2 driveline 42 embodiment is adapted to be used with the Fig. 1 vehicle 10, but it is also envisaged that other embodiments of the driveline 20 42 may be adapted to be used with other types of vehicle 10.

As is indicated in Fig. 2, the driveline 42 comprises a power source 44. In the Fig. 2 embodiment, the power source 44 is exemplified as an internal combustion engine. However, it is also envisaged that embodiments of the driveline 42 may comprise another 25 type of power source 44 such as an electrical motor, a hybrid engine or a fuel cell (not shown).

Moreover, as is indicated in Fig. 2, the driveline 42 further comprises at least one front axle and at least one rear axle. In fact, and as has been intimated hereinabove with 30 reference to Fig. 1 , the Fig. 2 embodiment of the driveline comprises three axles: a front axle 16, a front rear axle 26 and a back rear axle 28.

The driveline 42 further comprises a main gearbox 46. The main gearbox 46, which may be an automatic gearbox or a manually operated gearbox, is operationally connected to 35 an output shaft from the power source 44. The driveline 42 also comprises a transmission assembly 48 for distributing driving power between the front axle 16 and the two rear axles 26, 28. The transmission assembly 48 may also be referred to as a transfer gearbox, a distribution gearbox or an intermediate gearbox. The main gearbox 46 is in the Fig. 2 embodiment is operably connected to the transmission assembly 48 via a transmission drive shaft 50.

A first, second and third drive shaft 52, 54, 56 (which may also be referred to as propeller shafts) extend substantially in the longitudinal direction of the vehicle and are each operably connected to the transmission assembly 48 and a central gear 58, 60, 62 in each of the propulsion axles 16, 26, 28. As may be gleaned from Fig. 2, in the embodiment of the driveline 42 illustrated therein, the second drive shaft 54 operably connects the transmission assembly 48 to the central gear 60 associated with the front rear axle 26 and the third drive shaft 56 operably connects the central gear 60 of the front rear axle 26 with the central gear 62 of the back rear axle 28.

In the Fig. 2 embodiment of the driveline 42, each propulsion axle 16, 26, 28 comprises a pair of transverse drive shafts (stick axles) extending in opposite directions from the respective central gear 58, 60, 62. Each of the transverse drive shafts drives one of the ground engagement elements 18, 30, 32.

As has been intimated hereinabove, the transmission assembly 48 is adapted to distribute driving power between a front axle and a rear wheel axle. In the Fig. 2 embodiment, the transmission assembly 48 is adapted to distribute driving power between the first drive shaft 52 and the second drive shaft 54. Consequently, in the Fig. 2 embodiment, the transmission assembly 48 is adapted to distribute driving power between the front axle 16 and the pair of rear axles 26, 28.

Fig. 3 schematically illustrates an embodiment of a transmission assembly 48 which for instance can be used in the Fig. 2 driveline 42 embodiment. As may be gleaned from Fig. 3, the transmission assembly 48 comprises an input shaft 64 and an output shaft 66.

Moreover, the Fig. 3 transmission assembly 48 comprises a planetary gear assembly 68 which in turn comprises a ring gear 70, a first sun gear 72 and a second sun gear 74. The Fig. 3 planetary gear assembly 68 is illustrated in Fig. 4. As is indicated in Fig. 4, the planetary gear assembly 68 comprises a planet gear connecting assembly 76 connecting the ring gear 70 to each one of the first and second sun gears 72, 74.

Moreover, as illustrated in Fig. 4, the planet gear connecting assembly 76 comprises a 5 radially outward planet gear 78 and a radially inward planet gear 80. The radially inward planet gear 80 meshes with the radially outward planet gear 78. Moreover, in the embodiment illustrated in Fig. 3, the radially outward planet gear 78 and the radially inward planet gear 80 are connected to one another via a common planet carrier 82. Further, Fig. 4 illustrates that the input shaft 64 is connected to the common planet carrier 10 82.

Each one of the first sun gear 72 and the second sun gear 74 is connected to the planet gear connecting assembly 76. In particular, the first sun gear 72 meshes with the radially outward planet gear 78 and the second sun gear 74 meshes with the radially inward

15 planet gear 80.

As such, in the embodiment illustrated in Fig. 3, only one component, viz the radially outward planet gear 78, transfers rotation between the first sun gear 72 and the ring gear 70. Moreover, in the Fig. 3 embodiment, two components, viz the radially outward planet 20 gear 78 as well as the radially inward planet gear 80, transfer rotation between the second sun gear 74 and the ring gear 70.

In order to control the torque transmission between the input shaft 64 and an output shaft 66, each one of the second sun gear 74 and the ring gear 70 may be selectively and 25 individually connectable to the output shaft 66. The ability to selectively and individually connect each one of the second sun gear 74 and the ring gear 70 to the output shaft 66 may be achieved in a plurality of ways.

To this end, reference is made to Fig. 3 illustrating that the transmission assembly 48 may 30 comprise a connecting mechanism 84 for the second sun gear 74. The second sun gear connecting mechanism 84 is adapted to assume an engaged condition in which the second sun gear 74 is operatively connected to the output shaft 66 and a disengaged condition in which the second sun gear 74 is not operatively connected to the output shaft 66.

35 The connecting mechanism 84 for the second sun gear 74 is in the Fig. 3 embodiment exemplified as a friction clutch. However, it is also envisaged that implementations of the connecting mechanism 84 for the second sun gear 74 may comprise a dog clutch or a one-way clutch (not shown).

Moreover, Fig. 3 also illustrates that the embodiment of the transmission assembly 48 illustrated therein further comprises a connecting mechanism 86 for the ring gear 70. The ring gear connecting mechanism 86 is adapted to assume an engaged condition in which the ring gear 70 is operatively connected to the output shaft 66 and a disengaged condition in which the ring gear 70 is not operatively connected to the output shaft 66. The connecting mechanism 86 for the ring gear 70 is in the Fig. 3 embodiment exemplified as a friction clutch. However, it is also envisaged that implementations of the connecting mechanism 86 for the ring gear 70 may comprise a dog clutch or a one-way clutch (not shown).

Purely by way of example, the planetary gear assembly 68 has a first gear ratio via the ring gear 70, the radially outward planet gear 78 and the first sun gear 72. Moreover, the planetary gear assembly 68 may for instance also have a second gear ratio via the ring gear 70, the radially outward planet gear 78, the radially inward planet gear 80 and the second sun gear 74. Purely by way of example, the first gear ratio may be negative whereas the second gear ratio may be positive. As a further non-limiting example, the first gear ratio may be different from the second gear ratio.

In the Fig. 3 embodiment, the transmission assembly 48 further comprises an additional output shaft 88. However, it is also envisaged that embodiments of the transmission assembly comprise only one output shaft 66. The additional output shaft 88 illustrated in Fig. 3 is connected to the first sun gear 72. As may be gleaned from Fig. 3, in the embodiment disclosed therein, the first sun gear 72 is connected to the additional output shaft 88 via a first sun gear transmission component 90. In the Fig. 3 embodiment, the first sun gear transmission component 90 encloses the planet gear connecting assembly 76 and the connecting mechanism 84 for the second sun gear 72 as well as the connecting mechanism 86 for the ring gear 70. Moreover, in the Fig. 3 embodiment, each one of the connecting mechanism 84 for the second sun gear 72 and the connecting mechanism 86 for the ring gear 70 is located between the planet gear connecting assembly 76 and the additional output shaft 88. As has been intimated hereinabove, the Fig. 3 transmission assembly 48 may be used for distributing torque between two propelling axes of a driveline comprising a power source 42 and at least the two propelling axes 16, 26. As such, the input shaft 64 of the Fig. 3 transmission assembly 48 may be operably connectable to a power source 44, the output shaft 66 may be operably connectable to a propelling axle 26 and the additional output shaft 88 may be operably connectable to another propelling axle 16 of the above- mentioned driveline. By operating the connecting mechanism 84 for the second sun gear 74 and the connecting mechanism 86 for the ring gear 70, it can be selected which one of the second sun gear 74 and the ring gear 70 that should be connected to the output shaft 66. As such, by operating the connecting mechanisms 84, 88, the torque transfer from the input shaft 64 to the output shaft 66 may be set. The input shaft torque not transferred to the output shaft 66 is consequently transferred to the additional output shaft 88.

Thus, by virtue of the transmission assembly 48, it is possible to select between two different levels of the torque distribution between two propelling axes of a driveline 42. As indicated in Fig. 3, the transmission assembly 48 may form part of the Fig. 2 driveline 42. In such an embodiment, the input shaft 64 may be operably connected to the Fig. 2 power source 44, for instance via the Fig. 2 transmission drive shaft 50.

Moreover, the output shaft 66 illustrated in Fig. 3 may be operably connected to one of the Fig. 2 first drive shaft 52 and the second drive shaft 54, and the additional output shaft 88 may be operably connected to the other one of the Fig. 2 first drive shaft 52 and the second drive shaft 54.

Purely by way of example, and as indicated in the Fig. 3 embodiment, the output shaft 66 may be operably connected to the second drive shaft 54, and the additional output shaft 88 may be operably connected to the first drive shaft 52. As such, in the Fig. 3 embodiment, the output shaft 66 may be operably connected to the rear axles 26, 28 and the additional output shaft 88 may be operably connected to the front axle 16. Purely by way of example, and as indicated in Fig. 3, the additional output shaft 88 may be operably connected to the first drive shaft 52 via a gear assembly 92.

In order to control the operation of the connecting mechanism 84 for the second sun gear 5 74 and the connecting mechanism 86 for the ring gear 70, a control unit 94 may be used.

Purely by way of example, the control unit 94 may form part of a transmission assembly 48 and/or of a driveline 42 and/or of a vehicle 10. However, it is also contemplated that the control unit 94 may be separate from the vehicle 10 and that the control unit 94 may communicate with the connecting mechanisms 84, 86 using communication means, for 10 instance wireless communication means (not shown).

Purely by way of example, the control unit 94 may be an electronic control unit. As a non- limiting example, the electronic control unit may comprise a computer program comprising program code means and/or a computer readable medium carrying a computer program 15 comprising program code means.

Irrespective of the configuration of the control unit 94, the control unit 94 may be adapted to issue a first torque distribution signal to the planetary gear assembly 68 to obtain a first torque distribution between the at least one front axle 16 and the at least one rear axle 26, 20 28 for instance by arranging the ring gear 70 connected to the output shaft 66 and arranging the second sun gear 74 disconnected from the output shaft 66.

Moreover, as is indicated in Fig. 3, the control unit 94 may be adapted to receive a load condition signal indicative of a load condition of the vehicle. To this end, the vehicle may 25 comprise a sensor assembly 96 comprising one or more sensors, e.g. load sensors.

Purely by way of example, the sensor assembly 96 may be adapted to determine a current weight and/or centre of gravity of the vehicle. As another non-limiting example, the sensor assembly 96 may be adapted to determine a current weight and/or centre of 30 gravity of the load of the vehicle. The control unit 94 may be adapted to receive a signal from the sensor assembly 96 and to issue a signal to the planetary gear assembly 48 in response to the load condition signal.

The first torque distribution may result in a first torque portion imparted on the at least one 35 rear axle 26, 28 and the second torque distribution may result in a second torque portion imparted on the at least one rear axle 26, 28. Purely by way of example, the first torque portion is greater than the second torque portion.

As a non-limiting example, the control unit 94 may be adapted to determine, on the basis of the load condition signal, if the vehicle 10 is in a loaded condition. Purely by way of example, the control unit 94 may be adapted to determine that the vehicle 10 is in a loaded condition by determining that the weight of the vehicle, including its load, exceeds a predetermined threshold vehicle weight. As another non-limiting example, the control unit 94 may be adapted to determine that the vehicle 10 is in a loaded condition by determining that the weight of a load of the vehicle exceeds a predetermined threshold load weight. Further, as another example, the control unit 94 may be adapted to determine that the vehicle 10 is in a loaded condition by determining that the centre of gravity of the vehicle, including its load, for instance the longitudinal centre of gravity, is located within a predetermined spatial range.

Regardless of how the control unit 94 determines whether or not the vehicle 10 is in a loaded condition, upon determination that the vehicle 10 is in the loaded condition, the control unit 94 may be adapted to issue the first torque distribution signal. As another non-limiting example, the control unit 94 may be adapted to issue a second torque distribution signal to the planetary gear 48 assembly to obtain a second torque distribution between the at least one front axle 52 and the at least one rear axle 26, 28 by arranging the ring gear 70 disconnected from the output shaft 66 and arranging the second sun gear 74 connected to the output shaft 66.

Moreover, the control unit 94 may be adapted to determine, on the basis of the load condition signal, if the vehicle 10 is in an unloaded condition. Purely by way of example, the control unit 94 may be adapted to determine if the vehicle 10 is in an unloaded condition using any one of the above procedures that have been discussed hereinabove for determining if the vehicle 10 is in a loaded condition. For instance, if any one of the above procedures does not result in the determination that the vehicle 10 is in a loaded condition, the control unit 94 may be adapted to determine that the vehicle 10 is in an unloaded condition. Upon determination that the vehicle 10 is in the unloaded condition, the control unit 94 may be adapted to issue the second torque distribution signal. Optionally, the control unit 94 may be adapted to issue a lock-up signal to the planetary gear assembly 48 to obtain a condition between the at least one front axle 52 and the at least one rear axle 54 by arranging the second sun gear 74 connected to the output shaft 66 and also arranging the ring gear 70 connected to the output shaft 66.

Fig. 5 illustrates another embodiment of the transmission assembly 48. As may be gleaned from Fig. 5, the transmission assembly 48 illustrated therein comprises a plurality of features that are similar to the Fig. 3 and Fig. 4 embodiment. Consequently, such features are not repeated here. However, as compared to the Fig. 3 embodiment, the input shaft 64 is connected to the common planet carrier 82 via an input shaft transmission component 98. In the Fig. 5 embodiment, the input shaft transmission component 98 at least partially encloses the planet gear connecting assembly 76 and the connecting mechanism 84 for the second sun gear 72 as well as the connecting mechanism 86 for the ring gear 70. Moreover, in the Fig. 5 embodiment, planet gear connecting assembly 76 is located between the additional output shaft 88 and each one of the connecting mechanism 84 for the second sun gear 72 as well as the connecting mechanism 86 for the ring gear 70.

Fig. 6 schematically illustrates another embodiment a transmission assembly 48 which for instance can be used in the Fig. 2 driveline 42 embodiment. As may be gleaned from Fig. 6, the transmission assembly 48 comprises an input shaft 64 and an output shaft 66.

Moreover, the Fig. 6 transmission assembly 48 comprises a planetary gear assembly 100. The Fig. 6 planetary gear assembly 100 is illustrated in Fig. 7. As is indicated in Fig. 7, the planetary gear assembly 100 comprises a ring gear 102, a first planet gear set 104, a second planet gear set 106, as well as a first sun gear 108 and a second sun gear 1 10.

The ring gear 102 is connected to the input shaft 64. Each one of the first and second planet gear sets 104, 106 is connected to a common planet carrier 1 12 as well as being connected to the ring gear 102. The first planet gear set 104 is connected to the first sun gear 108 and the second planet gear set 106 is connected to the second sun gear 1 10. Each one of the first sun gear 108 and the second sun gear 1 10 is selectively and individually connectable to the output shaft (not shown in Fig. 7). The first and second planet gear sets 104, 106, as well as the common planet carrier 1 12, form a planet gear connecting assembly 76. In the Fig. 6 and Fig. 7 embodiment, the first planet gear set 104 comprises an outer first planet gear 1 14 and an inner first planet gear 1 16. The outer first planet gear 1 14 meshes with the ring gear 102 and the inner first planet gear 1 16, whereas the inner first planet 5 gear 1 16 meshes with the outer first planet gear 1 14 and the first sun gear 108.

In a similar vein, in the Fig. 6 and Fig. 7 embodiment, the second planet gear set 106 comprises an outer second planet gear 1 18 and an inner second planet gear 120. The outer second planet gear 1 18 meshes with the ring gear 102 and the inner second planet 10 gear 120, whereas the inner second planet gear 120 meshes with the outer second planet gear 1 18 and the second sun gear 1 10.

In order to control the torque transmission between the input shaft 64 and an output shaft 66, each one of the first sun gear 108 and the second sun gear 1 10 may be selectively 15 and individually connectable to the output shaft 66. The ability to selectively and

individually connect each one of the first sun gear 108 and the second sun gear 1 10 to the output shaft 66 may be achieved in a plurality of ways.

To this end, reference is made to Fig. 6 illustrating that the transmission assembly 48 may 20 comprise a connecting mechanism 122 for the first sun gear 108. The first sun gear

connecting mechanism 122 is adapted to assume an engaged condition in which the first sun gear 108 is operatively connected to the output shaft 66 and a disengaged condition in which the first sun gear 108 is not operatively connected to the output shaft 66. The connecting mechanism 122 for the first sun gear 108 is in the Fig. 6 embodiment

25 exemplified as a friction clutch. However, it is also envisaged that implementations of the connecting mechanism 122 for the first sun gear 108 may comprise a dog clutch or a oneway clutch (not shown).

Moreover, Fig. 6 also illustrates that the embodiment of the transmission assembly 48 30 illustrated therein further comprises a connecting mechanism 124 for the second sun gear 1 10. The second sun gear connecting mechanism 124 is adapted to assume an engaged condition in which the second sun gear 1 10 is operatively connected to the output shaft 66 and a disengaged condition in which the second sun gear 1 10 is not operatively connected to the output shaft 66. The connecting mechanism 124 for the second sun gear 35 1 10 is in the Fig. 6 embodiment exemplified as a friction clutch. However, it is also envisaged that implementations of the connecting mechanism 124 for the second sun gear 1 10 may comprise a dog clutch or a one-way clutch (not shown).

Purely by way of example, each one of first and a second planet gear sets 104, 106 has a positive stationary gear ratio. Moreover, as another non-limiting example, the planetary gear assembly 100 has a first gear ratio via the ring gear 102, the first planet gear set 104 and the first sun gear 108. Further, the planetary gear assembly has a second gear ratio via the ring gear 102, the second planet gear set 106 and the second sun gear 1 10. As a non-limiting example, the first gear ratio is different from the second gear ratio.

In the Fig. 6 embodiment, the transmission assembly 48 further comprises an additional output shaft 88. The additional output shaft 88 is connected to the common planet carrier 1 12. As for the Fig. 3 and Fig. 5 embodiments, the Fig. 6 transmission assembly 48 may be used for distributing torque between two propelling axes of a driveline comprising a power source and at least the two propelling axes. As such, the input shaft 64 of the Fig. 6 transmission assembly 48 may be operably connectable to a power source 44, the output shaft 66 may be operably connectable to a propelling axle 16 and the additional output shaft 88 may be operably connectable to another propelling axle 26, 28 of the above- mentioned driveline.

Purely by way of example, and as indicated in Fig. 6, the transmission assembly 48 may form part of the Fig. 2 driveline 42. In such an embodiment, the input shaft 64 may be operably connected to the Fig. 2 power source 44, for instance via the Fig. 2 transmission drive shaft 50.

Moreover, the output shaft 66 illustrated in Fig. 6 may be operably connected to one of the Fig. 2 first drive shaft 52 and the second drive shaft 54, and the additional output shaft 88 may be operably connected to the other one of the Fig. 2 first drive shaft 52 and the second drive shaft 54. Purely by way of example, and as is indicated in the Fig. 6 embodiment, the output shaft 66 may be operably connected to the first drive shaft 52, and the additional output shaft 88 may be operably connected to the second drive shaft 54. As such, in the Fig. 6 embodiment, the output shaft 66 may be operably connected to the front axle 16 and the additional output shaft 88 may be operably connected to the rear axles 26, 28.

Purely by way of example, and as is indicated in Fig. 6, the output shaft 66 may be operably connected to the first drive shaft 52 via a gear assembly 126.

In order to control the operation of the connecting mechanism 122 for the first sun gear 108 and the connecting mechanism 124 for the second sun gear 1 10, a control unit 94 may be used. The control unit 94 may be adapted to receive signals from a sensor assembly 96. The control unit 94 and the sensor assembly 96 illustrated in Fig. 6 are configured in the same manner as the control unit 94 and the sensor assembly 96 that have been presented hereinabove in relation to Fig. 3. Consequently, details regarding the Fig. 6 control unit 94 and the sensor assembly 96 are not repeated here. As may be gleaned when comparing the Fig. 3 to Fig. 7 embodiments, the embodiments illustrated therein have a plurality of features is common.

For example, each one of the transmission assembly 48 embodiments comprises an input shaft 64, an output shaft 66 and an additional output shaft 88. Moreover, in each one of the embodiments, a power source 44 is operably connected to the input shaft 66, and the at least one front axle 16 is connected to one of the output shaft 66 and the additional output shaft 88. Here, it should be noted that in the embodiments illustrated in Fig. 3 to Fig. 5, the at least one front axle 16 is connected to the additional output shaft 88, whereas in the embodiment illustrated in Fig. 6 to Fig. 7, the at least one front axle 16 is connected to the output shaft 66.

Moreover, common to the Fig. 3 to Fig. 7 embodiments is that the at least one rear axle 26, 28 is connected to the other one of the one of the output shaft 66 and the additional output shaft 88.

Moreover, in the embodiments presented hereinabove, with reference to Fig. 3 to Fig. 7, the transmission assembly 48 comprises a planetary gear assembly 68; 100 which in turn comprises a ring gear 70; 102, a first and a second sun gear 72, 74; 108, 1 10 and a planet gear connecting assembly 76 connecting the ring gear 70; 102 to each one of the first and second sun gear 72, 74; 108, 1 10. Moreover, common to the Fig. 3 to Fig. 7 embodiments is that of the ring gear 70; 102, the first sun gear 72; 108 and the second sun gear 74; 1 10 constitute a first torque

transferring component adapted to be selectively and individually connectable to the output shaft 66. Moreover, one of the ring gear 70; 102, the first sun gear 72; 108 and the second sun gear 74; 1 10 constitutes a second torque transferring component adapted to be selectively and individually connectable to the output shaft 66. The first and second torque transferring components are different. The transmission assembly 48 according to for instance any one of the Fig. 3 to Fig. 7 embodiments is controllable so as to provide a first torque distribution between the at least one front axle 16 and the at least one rear axle 26, 28 by connecting the first torque transferring component to the output shaft 66 and disconnecting the second torque transferring component from the output shaft 66.

In the embodiments illustrated in Fig. 3 to Fig. 5, the first torque transferring component may be constituted by the ring gear 70 and the second torque transferring component may be constituted by the second sun gear 74. As another example, as exemplified in the Fig. 6 to Fig. 7 embodiment, the first torque transferring component may be constituted by the first sun gear 108 and the second torque transferring component is constituted by the second sun gear 1 10.

Moreover, the transmission assembly 48 in each one of the above-discussed

embodiments is controllable so as to provide a second torque distribution between the at least one front axle 16 and the at least one rear axle 26 by connecting the second torque transferring component to the output shaft 66 and disconnecting the first torque

transferring component from the output shaft 66. Fig. 8 illustrates a flow chart of a method according to the present invention. Purely by way of example, the Fig. 8 method may be carried out using the above-discussed control unit 94. However, it is also envisaged that the method may be carried out using other means (not shown) or that the method may be carried out manually. Moreover, the method may be carried out using any one of the transmission assembly 48 embodiments presented hereinabove. With reference to Fig. 8, the method comprises:

S10 detecting a load condition of the vehicle and

5 S12 controlling the transmission assembly so as to assume one of the first torque distribution and the second torque distribution in response to the detected load condition.

The step S10 may for instance be carried out by the control unit 94 in the manner that has 10 been described hereinabove with reference to e.g. Fig. 3 or Fig. 4.

Purely by way of example, the first torque distribution may result in a first torque portion imparted on the at least one rear axle 26, 28 and the second torque distribution may results in a second torque portion imparted on the at least one rear axle 26, 28. The first 15 torque portion may be greater than the second torque portion. Moreover, the method may comprise, upon detection that the vehicle is in a loaded condition, controlling the transmission assembly 48 such that the first torque distribution is obtained.

Furthermore, embodiments of the method may comprise: upon detection that the vehicle 20 10 is in an unloaded condition, controlling the transmission assembly 48 such that the second torque distribution is obtained.

Additionally, the transmission assembly 48, for instance according to any one of the embodiments discussed hereinabove with reference to Fig. 3 to Fig. 7, may be controlled 25 such that lock-up condition is obtained between the at least one front axle 16 and the at least one rear axle 26, 28 by arranging the first torque transferring component 74, 1 10 connected to the output shaft 66 and also arranging the second torque transferring component 70, 1 12 connected to the output shaft 66.

30 It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.