transmission

Abstract

A transmission system 101 for a work vehicle is provided. The transmission system comprises a hydraulic drive motor 38 and a transmission 100. The transmission includes: an output element 102; a first input element 104, which can be connected to a drive unit, the transmission being capable of transmitting drive from the first input element to the output element via a first drive path 108 in a mechanical drive mode; and a second input element 106, which can be driven by the operation of the hydraulic drive motor, the transmission being capable of transmitting drive from the second input element to the output element via a second drive path 110 in a hydrostatic drive mode. The transmission is configured such that, in the mechanical drive mode, there is a fixed ratio between the rotational speed of the first input element and the rotational speed of the output element.

Description

AREA

[0001] The present teachings relate to a transmission, a transmission system, a driveline assembly, and a work vehicle. BACKGROUND

[0002] Vehicles, such as work vehicles, typically include a driveline assembly that includes a prime mover, a transmission for transmitting mechanical power from the prime mover to a driveshaft, and a ground-engaging structure (including, for example, axles and wheels) driven by the driveshaft.

[0003] One common type of transmission is a mechanical transmission, which typically comprises a mechanical drive unit with several alternative gear ratios selectable using a gear ratio selector. Another common type of transmission is a hydrostatic transmission, which includes a hydraulic pump driven by the drive unit and a hydraulic drive motor supplied with hydraulic fluid from the hydraulic pump.

[0004] An object of the present teachings is to address one or more of the disadvantages inherent in the prior art. SUMMARY

[0005] One aspect of the teachings provides a transmission for a work vehicle including a ground-engaging structure. The transmission includes: an output member for driving the ground-engaging structure; a first input member connectable to a prime mover, the transmission operable to transmit drive from the first input member to the output member via a first drive path in a mechanical drive mode; and a second input member drivable by operation of a hydraulic drive motor, the transmission operable to transmit drive from the second input member to the output member via a second drive path in a hydrostatic drive mode. The transmission is configured such that, in the mechanical drive mode, there is a fixed ratio of the speed of the first input member to the speed of the output member.

[0006] In other words, the first drive path defines a fixed gear ratio, and there are no other drive paths connecting the first input member to the output member. This contrasts with arrangements that include a mechanical drive unit with multiple alternative gear ratios selectable with a gear ratio selection device.

[0007] One advantage of a fixed ratio of the speed of the first input member to the speed of the output member is that it reduces the number of required components compared to arrangements with drive units with multiple gear ratios. This provides a more compact transmission that is easier and more cost-effective to manufacture.

[0008] Furthermore, it has been demonstrated that adequate driving performance for a work vehicle can be achieved by having a hydrostatic drive mode for lower-speed travel and a mechanical drive mode with a fixed gear ratio for higher-speed travel. This contrasts with the conventional approach of having mechanical drive units with multiple alternative gear ratios for different travel speeds, even when an additional hydrostatic drive mode is provided.

[0009] Optionally, the first input member and the output member are spaced apart from each other at an intermediate distance transverse to their respective axes of rotation, the intermediate distance being at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm.

[0010] In other words, the transmission is configured to connect a drive unit having a rotational axis to one or more drive shafts (for driving the ground engaging structure) having a rotational axis and spaced at such an intermediate distance from the drive unit transverse to the respective rotational axes.

[0011] Optionally, the transmission is configured for mounting in a driveline arrangement such that the first input member is provided vertically above the output member.

[0012] In other words, the transmission is configured for mounting in a driveline arrangement such that the intermediate distance between the first input member and the output member is a vertical distance. In other words, such a transmission is configured to be provided in a "long-drop" configuration, which is useful for applications where the power plant has an output shaft that is significantly higher than a drive shaft of the work vehicle. For example, in articulated loaders or telehandlers where the prime mover is mounted higher than in other work vehicles, such as fixed-body telehandlers.

[0013] Optionally, the transmission comprises a first side and a second side, wherein the first input member on the first side of the transmission is connectable to a drive unit and wherein the second input member on the first side of the transmission is connectable to the hydraulic drive motor.

[0014] In other words, when the transmission is provided as part of a driveline arrangement, both input drives (power pack / hydraulic drive motor) are located on the same side of the transmission, rather than on opposite sides of the transmission. This can allow for a more compact arrangement on the second side of the transmission, which can be particularly useful for articulated work vehicles, such as articulated loaders or telescopic articulated loaders.

[0015] Optionally, the transmission includes a first clutch device having an engaged state configured to connect the first input member to the first drive path when the transmission is in the mechanical drive mode and a disengaged state configured to disconnect the first input member from the first drive path when the transmission is in the hydrostatic drive mode.

[0016] Such a first clutch device provides a simple means for selectively placing the transmission into the mechanical drive mode.

[0017] Optionally, the transmission includes a second clutch device having an engaged state configured to connect the second input member to the second drive path when the transmission is in the hydrostatic drive mode and a disengaged state configured to disconnect the second input member from the second drive path when the transmission is in the mechanical drive mode.

[0018] Such a second clutch device provides a simple means for selectively placing the transmission into the hydrostatic drive mode.

[0019] Optionally, the first drive path comprises: a first input gear configured for rotation with the first input member when the transmission is in the mechanical drive mode, an output gear carried on the output member for rotation with the output member, a first intermediate shaft between the first input member and the output member, and one or more intermediate gears carried on the first intermediate shaft for rotation with the first intermediate shaft, wherein each of the one or more intermediate gears of the first intermediate shaft always meshes with the first input gear and / or the output gear.

[0020] Such an arrangement provides a simple means for transferring drive from the first input member to the output member. Furthermore, an intermediate shaft (rather than directly meshing the first input gear and the output gear) provides greater flexibility in packaging the transmission. For example, the first input member and the output member can be spaced a greater distance apart, which can be useful in applications where an output shaft of the prime mover is spaced apart from a drive shaft of the work vehicle.

[0021] Optionally, the one or more intermediate gears of the first intermediate shaft may comprise a single idler gear that always meshes with both the first input gear and the output gear.

[0022] Such an idler gear allows the distance between the first input gear and the output gear to be increased without affecting the fixed gear ratio. This can be useful in applications where the drive unit's output shaft is spaced a long distance from the work vehicle's drive shaft.

[0023] Optionally, the first input gear, the idler gear, and the output gear are arranged in an approximately vertical line, with the idler gear positioned below the first input gear and the output gear positioned below the idler gear.

[0024] Such an arrangement provides a "long-drop" configuration, which is useful in applications where a power unit output shaft is significantly higher than a work vehicle drive shaft. For example, in articulated loaders or telehandlers, where the power unit is mounted higher than in other work vehicles, such as fixed-body telehandlers.

[0025] Optionally, the second drive path comprises: a second input gear configured for rotation with the second input member when the transmission is in the hydrostatic drive mode, an output gear carried on the output member for rotation with the output member, a second intermediate shaft between the second input gear and the output gear, and one or more intermediate gears carried on the second intermediate shaft for rotation with the second intermediate shaft, wherein each of the one or more intermediate gears of the second intermediate shaft always meshes with the second input gear and / or the output gear.

[0026] Such an arrangement provides a simple means for transferring drive from the second input member to the output member. Furthermore, an intermediate shaft (rather than directly meshing the second input gear and the output gear) provides greater flexibility in the packaging of the transmission. For example, a gear ratio between the second input gear and the output gear can be determined by selecting the number of teeth on the intermediate gears on the intermediate shaft, without having to change the size of the second input gear or the output gear.

[0027] Optionally, the one or more intermediate gears of the second intermediate shaft comprise a first intermediate gear that always meshes with the second input gear and a second intermediate gear that always meshes with the output gear.

[0028] In this way, a gear ratio between the second input gear and the output gear can be set by selecting the number of teeth on the first and second intermediate gears without having to change the size of the second input gear or the output gear.

[0029] Optionally, the first intermediate gear has more teeth than the second intermediate gear.

[0030] In this way, a gear ratio between the second input gear and the output gear can be influenced by the different number of teeth of the first and second intermediate gear.

[0031] Optionally, the transmission comprises a V-shaped structure, wherein the output member is provided at a lower end of the V-shaped structure, the first input member and the first intermediate shaft define a first side of the V-shaped structure, and the second input member and the second intermediate shaft define a second side of the V-shaped structure.

[0032] Such a V-shaped design provides a package that can be easily reconfigured by removing one side of the V-shaped design. For example, in applications where only a hydrostatic drive mode is required, the first input member and the first intermediate shaft can simply be omitted, as they are located on a different side of the V-shaped configuration, without requiring any modification of the transmission housing.

[0033] Another aspect of the teachings provides a transmission system including a hydraulic drive motor and a transmission according to the present disclosure.

[0034] Optionally, the transmission system further comprises a control system configured to place the transmission in hydrostatic drive mode when the work vehicle is traveling at speeds below a threshold speed and to place the transmission in mechanical drive mode when the work vehicle is traveling at speeds equal to or greater than the threshold speed.

[0035] Optionally, the threshold speed is more than 20 km / h, optionally more than 25 km / h, optionally more than 30 km / h, optionally more than 35 km / h, optionally more than 40 km / h.

[0036] Known hydrostatic drives in hybrid transmissions are limited to speeds below 20 km / h, with a mechanical drive being used for speeds above 20 km / h. Since work vehicles must occasionally travel at speeds much higher than 20 km / h (e.g., when driving on the road), the mechanical drives in such transmissions use multiple gear ratios. For example, the mechanical drive may have a first gear ratio optimized for speeds of 20-30 km / h, a second gear ratio optimized for speeds of 30-40 km / h, and a third gear ratio optimized for speeds above 40 km / h. However, it has been shown that by setting a threshold speed for the hydrostatic drive mode higher than 20 km / h (e.g.,(more than 25, 30, 35, or 40 km / h), good mechanical drive performance can be achieved with a fixed gear ratio. This allows a reduction in the number of transmission components, simplifying manufacturing and reducing costs.

[0037] Another aspect of the teachings provides a driveline assembly for a work vehicle including a ground-engaging structure, the driveline assembly including a transmission according to the present disclosure. Such a driveline assembly benefits from the advantages of the transmission set forth above.

[0038] Optionally, the drive train arrangement includes a drive unit configured to drive the first input member of the transmission.

[0039] Optionally, the driveline assembly includes a hydraulic drive motor configured to drive the second input member of the transmission.

[0040] Optionally, the drive train assembly includes a hydraulic pump for supplying pressurized hydraulic fluid to drive the hydraulic drive motor. Optionally, the hydraulic pump can be driven by the drive unit.

[0041] Optionally, the driveline assembly includes one or more output drive shafts coupled to the output member of the transmission for driving the ground engaging structure of the work vehicle.

[0042] Optionally, the hydraulic pump is a hydraulic pump with a through drive, which is positioned between the drive unit and the first input link of the transmission.

[0043] In other words, the hydraulic pump comprises an input side which is directly coupled to an output drive shaft of the drive unit and an output side which is directly coupled to an intermediate drive shaft for driving the first input member of the transmission.

[0044] Such a configuration provides a more compact driveline arrangement than alternative arrangements, such as arrangements in which the hydraulic pump is coupled to an output shaft of the transmission.

[0045] Optionally, the driveline assembly further comprises an intermediate drive shaft for driving the first input member of the transmission, wherein the hydraulic pump comprises an input side directly coupled to an output drive shaft of the drive unit and an output side directly coupled to the intermediate drive shaft.

[0046] Such a configuration provides a more compact driveline arrangement than alternative arrangements, such as arrangements in which the hydraulic pump is coupled to an output shaft of the transmission.

[0047] Optionally, the hydraulic pump can be mounted directly to the drive unit, providing a compact arrangement.

[0048] Optionally, the first input member of the transmission and the output member of the transmission are spaced apart from each other at an intermediate distance transverse to their respective axes of rotation, the intermediate distance being at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm.

[0049] In other words, the transmission is configured to connect a power unit to one or more drive shafts (for driving the ground-engaging structure) spaced from the power unit at such a distance. In other words, such a transmission provides a "long-drop" configuration, which is useful in applications where an output shaft of the power unit is significantly higher than a drive shaft of the work vehicle. For example, in articulated loaders or telehandlers, where the prime mover is mounted higher than in other work vehicles, such as fixed-body telehandlers.

[0050] Optionally, the gearbox is arranged so that the first input member is positioned vertically above the output member.

[0051] Optionally, the power pack and hydraulic drive motor are positioned on the same side of the transmission. This can allow for a more compact arrangement on an opposite side of the transmission, which can be particularly useful for articulated work vehicles, such as articulated loaders or telescopic articulated loaders.

[0052] Another aspect of the teachings provides a driveline assembly for a work vehicle including a ground-engaging structure. The driveline assembly includes: a transmission including an output member, a first input member for driving the output member in a mechanical drive mode, and a second input member for driving the output member in a hydrostatic drive mode; a prime mover configured to drive the first input member of the transmission; a hydraulic drive motor configured to drive the second input member of the transmission; a hydraulic pump for supplying pressurized hydraulic fluid to drive the hydraulic drive motor, the hydraulic pump drivable by the prime mover; and one or more output drive shafts coupled to the output member of the transmission for driving the ground-engaging structure of the work vehicle.The hydraulic pump is a hydraulic pump with a through drive, which is positioned between the drive unit and the first input link of the transmission.

[0053] In other words, the hydraulic pump comprises an input side which is directly coupled to an output drive shaft of the drive unit and an output side which is directly coupled to an intermediate drive shaft for driving the first input member of the transmission.

[0054] Such a configuration provides a more compact driveline arrangement than alternative arrangements, such as arrangements in which the hydraulic pump is coupled to an output shaft of the transmission.

[0055] Optionally, the driveline assembly further comprises an intermediate drive shaft for driving the first input member of the transmission, wherein the hydraulic pump comprises an input side directly coupled to an output drive shaft of the drive unit and an output side directly coupled to the intermediate drive shaft.

[0056] Such a configuration provides a more compact driveline arrangement than alternative arrangements, such as arrangements in which the hydraulic pump is coupled to an output shaft of the transmission.

[0057] Optionally, the hydraulic pump can be mounted directly to the drive unit, providing a compact arrangement.

[0058] Optionally, the first input member of the transmission and the output member of the transmission are spaced apart from each other at an intermediate distance transverse to their respective axes of rotation, the intermediate distance being at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm.

[0059] In other words, the transmission is configured to connect a power unit to one or more drive shafts (for driving the ground-engaging structure) spaced from the power unit at such a distance. In other words, such a transmission provides a "long-drop" configuration, which is useful in applications where an output shaft of the power unit is significantly higher than a drive shaft of the work vehicle. For example, in articulated loaders or telehandlers, where the prime mover is mounted higher than in other work vehicles, such as fixed-body telehandlers.

[0060] Optionally, the gearbox is arranged so that the first input member is positioned vertically above the output member.

[0061] Optionally, the power pack and hydraulic drive motor are positioned on the same side of the transmission. This can allow for a more compact arrangement on an opposite side of the transmission, which can be particularly useful for articulated work vehicles, such as articulated loaders or telescopic articulated loaders.

[0062] Another aspect of the teachings provides a driveline assembly for a work vehicle including a ground-engaging structure. The driveline assembly includes: a transmission including an output member, a first input member for driving the output member in a mechanical drive mode, and a second input member for driving the output member in a hydrostatic drive mode; a prime mover configured to drive the first input member of the transmission; a hydraulic drive motor configured to drive the second input member of the transmission; a hydraulic pump for supplying pressurized hydraulic fluid to drive the hydraulic drive motor, the hydraulic pump drivable by the prime mover; and one or more output drive shafts coupled to the output member of the transmission for driving the ground-engaging structure of the work vehicle.The first input member of the transmission and the output member of the transmission are spaced apart from each other at an intermediate distance transverse to their respective axes of rotation, the intermediate distance being at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm.

[0063] In other words, the transmission is configured to connect a power unit to one or more drive shafts (for driving the ground-engaging structure) spaced from the power unit at such a distance. In other words, such a transmission provides a "long-drop" configuration, which is useful in applications where an output shaft of the power unit is significantly higher than a drive shaft of the work vehicle. For example, in articulated loaders or telehandlers, where the prime mover is mounted higher than in other work vehicles, such as fixed-body telehandlers.

[0064] Optionally, the gearbox is arranged so that the first input member is positioned vertically above the output member.

[0065] Optionally, the power pack and hydraulic drive motor are positioned on the same side of the transmission. This can allow for a more compact arrangement on an opposite side of the transmission, which can be particularly useful for articulated work vehicles, such as articulated loaders or telescopic articulated loaders.

[0066] Another aspect of the teachings provides a work vehicle including a driveline assembly according to the present disclosure and a ground engagement structure coupled to the one or more output drive shafts of the driveline assembly. Such a work vehicle benefits from the advantages of the driveline assembly set forth above.

[0067] Optionally, the work vehicle further comprises a control system configured to place the transmission in hydrostatic drive mode when the work vehicle is traveling at speeds below a threshold speed and to place the transmission in mechanical drive mode when the work vehicle is traveling at speeds equal to or greater than the threshold speed.

[0068] Optionally, the threshold speed is more than 20 km / h, optionally more than 25 km / h, optionally more than 30 km / h, optionally more than 35 km / h, optionally more than 40 km / h.

[0069] Known hydrostatic drives in hybrid transmissions are limited to speeds below 20 km / h, with a mechanical drive being used for speeds above 20 km / h. Since work vehicles must occasionally travel at speeds much higher than 20 km / h (e.g., when driving on the road), the mechanical drives in such transmissions use multiple gear ratios. For example, the mechanical drive may have a first gear ratio optimized for speeds of 20-30 km / h, a second gear ratio optimized for speeds of 30-40 km / h, and a third gear ratio optimized for speeds above 40 km / h. However, it has been shown that by setting a threshold speed for the hydrostatic drive mode higher than 20 km / h (e.g.,(more than 25, 30, 35, or 40 km / h), good mechanical drive performance can be achieved with a fixed gear ratio. This allows a reduction in the number of transmission components, simplifying manufacturing and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Embodiments will now be described by way of example only with reference to the accompanying figures, in which: Fig. 1 is a side view of a work vehicle according to an embodiment; Fig. 2 a schematic side view of a drive train arrangement of the work vehicle of Fig. 1; Fig. 3 a schematic plan view of the drive train arrangement of Fig. 2; Fig. 4 a first side view of the drive train arrangement of Fig. 2 and Fig. 3; Fig. 5 a second side view of the drive train arrangement of Fig. 2-4; Fig. 6 a plan view of the drive train arrangement of Fig. 2-5; Fig. 7 is a sectional view of a transmission of the drive train arrangement of Fig. 2-6; and Fig. 8 a perspective view of the gearbox of Fig. 7 with the case removed. DETAILED DESCRIPTION

[0071] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and the teachings. However, it will be apparent to one skilled in the art that: the present teachings may be practiced without these specific details or with known equivalents of these specific details; that the present teachings are not limited to the described embodiments; and that the present teachings may be practiced in many alternative embodiments. It is also understood that well-known methods, procedures, components, and systems may not have been described in detail.

[0072] References to vertical and horizontal in the present disclosure are to be understood with reference to the machine when it is standing on a horizontal floor in a non-working state. The term axial is generally used with reference to the longitudinal axis of the machine. The term width is generally used with reference to the longitudinal length, i.e., across the length.

[0073] Fig. 1 shows a work vehicle 10, which is an example of a type of vehicle to which the teachings may be applied.

[0074] A work vehicle is an off-road vehicle, for example those used in construction (e.g. backhoe loaders, excavators, swing excavators, telehandlers, forklifts, skid steer loaders, dump trucks, bulldozers, graders), agriculture (e.g. tractors, combine harvesters, self-propelled harvesters and field sprayers), open-pit mining (e.g. loading shovels, dump trucks) and forestry (e.g. timber harvesters, tree felling and skidding machines).

[0075] In the illustrated embodiment, the work vehicle 10 is a telescopic wheel loader. However, it should be understood that the teachings of other embodiments may be applied to other types of vehicles, jobs, or the like.

[0076] The Fig. The work vehicle 10 shown in Figure 1 is composed of a front chassis 12 and a rear chassis 22 which are connected to one another via an articulated connection 32, thereby allowing the front chassis 12 to pivot relative to the rear chassis 22.

[0077] The work vehicle has a ground-engaging structure 40 for moving the work vehicle 10 on the ground. In particular, the ground-engaging structure 40 includes a first set of wheels 14 provided on the front chassis 12 for moving the front chassis 12 on the ground. The first set of wheels 14 is connected via a first axle 15. The ground-engaging structure 40 further includes a second set of wheels 24 provided on the rear chassis 22 for moving the rear chassis 22 on the ground. The second set of wheels 24 is connected via a second axle 25.

[0078] A work arm 16 is attached to the front chassis 12 of the work vehicle 10. The work arm 16 includes a boom 16a pivotally mounted to the front chassis 12 and an attachment 16b pivotally mounted to a free end of the boom 16a. In the illustrated embodiment, the attachment 16b is a fork. In other embodiments, the attachment may be a bucket used for handling loose materials, such as grain or aggregate. However, in alternative embodiments, numerous alternative attachments may be used, such as a pallet fork, silage or manure forks, a bale grab, or a boom lift.

[0079] The work arm 16 is operatively connected to a series of hydraulic actuators (not shown) for raising and lowering the boom 16a and for tilting and operating the attachment 16b attached to the free end of the boom 16a. The manner in which the work arm 16 is operated is not critical to the present teachings and therefore will not be discussed in detail.

[0080] The work vehicle 10 also includes a drive unit (in Fig. 1 not shown) attached to the rear chassis 22. A cab 26 is further attached to the rear chassis 22 forward of the power unit. The cab 26 is provided with a selection of operating devices (not shown) for moving the work arm 16, maneuvering the work vehicle 10, and / or controlling other functions of the work vehicle 10.

[0081] As described below with reference to Fig. 2 to 6, during operation mechanical energy is transferred from the drive unit to a transmission, which then transfers the mechanical energy to the first and / or second axle via one or more drive shafts.

[0082] With reference now to Fig. 2 to 6, the drive train arrangement of the work vehicle 10 is indicated by 20.

[0083] The driveline assembly 20 includes a drive unit 34, a hydraulic pump 36, a hydraulic drive motor 38, a transmission 100, and one or more output drive shafts 42a, 42b for driving the ground engaging structure 40 of the work vehicle 10.

[0084] The powerplant 34 converts chemical or electrical energy into mechanical energy to drive the wheels 14, 24 of the work vehicle 10. In the illustrated embodiment, the powerplant 34 is a prime mover. In particular, the powerplant 34 is an internal combustion engine that converts chemical energy in the form of petroleum fuel (e.g., diesel or gasoline) into mechanical energy to drive the wheels 14, 24 of the work vehicle 10. However, in other embodiments, the powerplant 34 may be a hydrogen-fueled internal combustion engine (or HICE), an electric motor powered by a hydrogen fuel cell or batteries, or a combination of the above.

[0085] As described in more detail below, the transmission 100 includes an output member 102, a first input member 104 for driving the output member 102 in a mechanical drive mode, and a second input member 106 for driving the output member 102 in a hydrostatic drive mode. The transmission 100 is operable to receive drive from the first and second input members 104, 106 via first and second drive paths 108, 110, respectively (in Fig. 2 schematically shown by the dashed lines) to the output element 102.

[0086] The one or more output drive shafts 42a, 42b are coupled to the output member 102 of the transmission 100. In this way, drive transmitted from the first and second input members 104, 106 via the first and second drive paths 108, 110, respectively, to the output member 102 can be used to drive the ground engaging structure 40 of the work vehicle 10. In the illustrated embodiment, there is a first output drive shaft 42a that transmits drive from the output member 102 of the transmission to the first axle 15. The first output drive shaft 42a includes a universal joint 48 that divides the first output drive shaft 42a into a rear portion 50a and a front portion 50b (in Fig. 4 to 6). This universal joint 48 allows the first output drive shaft 42a to pivot with the articulation 32 of the telehandler while continuing to transmit drive to the first axle 15.

[0087] In the illustrated embodiment, there is also a second output drive shaft 42b that transmits drive from the output member 102 of the transmission 100 to the second axle 25. In this manner, the driveline assembly 20 can transmit drive to both the first and second axles 15, 25, and thus the work vehicle 10 has an all-wheel drive (or four-wheel drive) function.

[0088] In the illustrated embodiment, the first and second axles 15, 25 each comprise a gear set 43 (in Fig. 3), which converts rotation of the output drive shafts 42a, 42b into rotation of the respective axles 15, 25. The gear set 43 may be a differential device or any other suitable type of gear set known in the art.

[0089] In further embodiments, the driveline assembly 20 may only transfer drive to the first or second axle 15, 25 (ie, one of the output drive shafts 42a, 42b may be omitted). In such embodiments, the work vehicle 10 has only two-wheel drive capability.

[0090] The power pack 34 is configured to drive the first input member 104 of the transmission 100, and the hydraulic drive motor 38 is configured to drive the second input member 106 of the transmission 100. Thus, the transmission 100 is operable to transfer drive from the power pack 34 to the output member 102 in a mechanical drive mode or to transfer drive from the hydraulic drive motor 38 to the output member 102 in a hydrostatic drive mode.

[0091] The hydraulic pump 36 is configured to supply pressurized hydraulic fluid for driving the hydraulic drive motor 38. In particular, the hydraulic pump 36 is connected by a pair of hydraulic fluid lines 44a, 44b (which are shown in Fig. 2 schematically shown as dashed lines) is connected to the hydraulic drive motor 36. It is understood that the hydraulic pump 36 supplies pressurized hydraulic fluid to the hydraulic drive motor 38 along a first of the hydraulic fluid lines 44a, 44b, and the other of the hydraulic fluid lines 44a, 44b provides a return flow from the hydraulic drive motor 38 to the hydraulic pump 36. In this way, the hydraulic pump 36 and the hydraulic drive motor 38 are connected in a closed circuit. A hydraulic charge pump (not shown) and associated fluid lines may be provided for filling the closed circuit with hydraulic fluid (e.g., when starting the work vehicle 10).

[0092] In some embodiments, hydraulic fluid can be selectively supplied to the hydraulic drive motor 38 in either direction. This enables both forward and reverse movement of the work vehicle 10 using the hydrostatic drive mode of the transmission 100. This can be achieved with a bidirectional hydraulic pump 36 or by using one or more directional control valves provided between the hydraulic pump 36 and the hydraulic drive motor 38.

[0093] In the illustrated embodiment, the hydraulic pump 36 is drivable by the power unit 34. In particular, the hydraulic pump 36 is a through-drive hydraulic pump positioned between the power unit 34 and the first input member 104 of the transmission 100. In other words, the hydraulic pump 36 includes an input side 36a directly coupled to an output drive shaft of the power unit 34 and an output side 36b directly coupled to an intermediate drive shaft 46 for driving the first input member 104 of the transmission 100. In alternative embodiments, the hydraulic pump 36 is coupled to an output shaft of the transmission 100 (e.g., so that it is drivable by the power unit 34, but not with a through-drive between the power unit 34 and the transmission 100).

[0094] The drive-through configuration of the hydraulic pump 36 provides a compact driveline arrangement 20 suitable for work vehicles such as the telescopic wheel loader 10 of Fig. 1, is particularly advantageous. In particular, it will be appreciated that the transmission 100 must fit between the first and second axles 15, 25 so that the first and second output drive shafts 42a, 42b can be connected to the respective axles 15, 25. However, due to the articulated connection 32, the space in which the transmission 100 can be positioned (i.e., between the articulated connection 32 and the second axle 25) is relatively small. Thus, by providing the hydraulic pump 36 between the power unit 34 and the transmission 100 (e.g., as opposed to coupling it to an output shaft on a remote side of the transmission 100), the hydraulic pump 36 can be positioned in a region of the rear chassis 22 where there is comparatively more space.

[0095] In the illustrated embodiment, the hydraulic pump 36 is attached directly to the drive unit 34, providing a compact arrangement. In alternative embodiments, the hydraulic pump 36 is connected to the drive unit 34 via a further intermediate drive shaft.

[0096] In the illustrated embodiment, the drive unit 34 and the hydraulic drive motor 38 are positioned on the same side of the transmission 100, in particular on a rear side of the transmission 100. This allows for a more compact arrangement on an opposite side (ie, a front side) of the transmission 100, which is advantageous for work vehicles, such as the telescopic wheel loader 10 of Fig. 1, is particularly advantageous. In particular, as mentioned above, due to the limited space for positioning the transmission 100 between the articulation 32 and the second axle 25, there is comparatively more space at the rear of the transmission 100 than at the front. Thus, positioning the power pack 34 and the hydraulic drive motor 38 at the same rear of the transmission 100 allows these components to be positioned in an area of ​​the rear chassis 22 where there is comparatively more space.

[0097] In the illustrated embodiment, the first input member 104 of the transmission 100 and the output member 102 of the transmission are spaced apart from each other by a spaced distance D transverse to their respective axes of rotation. In the illustrated embodiment, the spaced distance D is at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm. For example, the spaced distance D may be approximately 340 mm. In other words, the transmission 100 is configured to connect a drive assembly (e.g., an output shaft of the drive assembly 34) to the output drive shafts 42a, 42b, which are spaced apart from the drive assembly by such a spaced distance D. In other words, such a transmission 100 provides a "long-drop" configuration.

[0098] The “long drop” configuration is for work vehicles such as the telescopic wheel loader 10 from Fig. 1 particularly advantageous. In particular, as in Fig. 1, the rear chassis 22 has an enclosed space 35 (e.g. an engine compartment) in which the drive unit 34 is accommodated and which is located relatively high in the work vehicle 10 compared to the first and second axles 15, 25 and the associated drive shafts 42a, 42b.

[0099] In the illustrated embodiment, the transmission 100 is arranged such that the first input member 104 is provided vertically above the output member 102, thereby enabling the "long drop" configuration from the powerplant 34 sloping to the drive shafts 42a, 42b, as described above.

[0100] With reference now to Fig. 7 and Fig. 8, the transmission 100 of the driveline assembly 20 is shown in more detail. The transmission 100 has a number of internal components in a housing 132. The housing 132 is shown in the cross-sectional view of Fig. 7, but was used in the perspective view of Fig. 8 is omitted to clearly show the internal components of the transmission 100.

[0101] As mentioned above, the transmission 100 includes an output member 102 for driving the ground-engaging structure 40 of the work vehicle 10. The transmission 100 also includes a first input member 104 connectable to a power plant (e.g., to an output shaft of the power plant 34), and the transmission 100 is operable to transmit drive from the first input member 104 via a first drive path 108 to the output member 102 in a mechanical drive mode. The transmission 100 also includes a second input member 106 drivable by operation of the hydraulic drive motor 38, and the transmission 100 is operable to transmit drive from the second input member 106 via a second drive path 110 to the output member 102 in a hydrostatic drive mode.

[0102] In the illustrated embodiment, the output member 102 includes splines 105 (outer splines in this embodiment) at each end for coupling to the output drive shafts 42a, 42b of the driveline assembly 20. Similarly, the first input member 104 includes splines 105 (outer splines in this embodiment) at one end for coupling to the intermediate drive shaft 46 of the driveline assembly 20 (or directly to an output shaft of the powerplant 34 in other embodiments). Similarly, the second input member 106 includes splines 105 (inner splines in this embodiment) at one end for coupling to an output shaft of the hydraulic drive motor 38.It will be understood that in other embodiments, other combinations of internal or external splines 105 may be provided, or the output member 102 and the input members 104, 106 may be configured for coupling to the respective shafts via other means (e.g., using threaded pins or the like).

[0103] In the illustrated embodiment, the transmission 100 is configured such that, in the mechanical drive mode, there is a fixed ratio of the speed of the first input member 104 to the speed of the output member 102. In other words, the first drive path 108 defines a fixed gear ratio, and there are no other drive paths connecting the first input member 104 to the output member 102. This contrasts with arrangements that include a mechanical drive unit with multiple alternative gear ratios selectable with a gear ratio selector.

[0104] An advantage of a fixed ratio of the speed of the first input member 104 to the speed of the output member 102 is that it reduces the number of required components compared to arrangements with drive units with multiple gear ratios. This provides a more compact transmission 100 that is easier and more cost-effective to manufacture. Furthermore, it has been found that adequate driving performance for a work vehicle 10 can be achieved by having a hydrostatic drive mode for lower-speed travel and a mechanical drive mode with a fixed gear ratio for higher-speed travel.This contrasts with the conventional approach where there are mechanical drive units with multiple alternative gear ratios for different travel speeds, even if an additional hydrostatic drive mode is provided.

[0105] It should be understood that the hydraulic drive motor 38 and the transmission 100 may be collectively considered a “transmission system” 101 that receives mechanical and hydrostatic inputs and converts them into a mechanical output.

[0106] The transmission system 101 includes a control system 112 configured to place the transmission 100 in hydrostatic drive mode when the work vehicle 10 is traveling at speeds below a threshold speed and to place the transmission 100 in mechanical drive mode when the work vehicle 10 is traveling at speeds greater than or equal to the threshold speed. Such a control system 112 may include a controller 113, which may be part of the work vehicle 10, as shown in Fig. 1 (e.g., a main ECU of the work vehicle 10).

[0107] The controller 113 may receive an input from a speed sensor 115 that provides a signal indicative of the travel speed of the work vehicle 10 (as indicated by the dashed line connecting the speed sensor 115 and the controller 113 in Fig. 8). The speed sensor 115 may include: a vehicle speedometer; a sensor configured to detect a rotation rate of a shaft of the transmission 100 (e.g., the output member 102); a sensor configured to detect a rotation rate of the output drive shafts 42a, 42b; a sensor configured to detect a rotation rate of the first and / or second axles 15, 25; a GPS sensor; or any other suitable sensor. In the illustrated embodiment, the speed sensor 115 is configured to detect gear teeth of the output gear 120 passing the speed sensor 115 to determine a rotation rate of the output member 102.

[0108] The controller 113 may send output signals configured to actuate a first and a second clutch device 114, 116 of the transmission 100 to effect the mechanical drive mode or the hydrostatic drive mode (as indicated by the dashed lines connecting the controller 113 and the clutch devices 114, 116 in Fig. 8). The first and second coupling devices 114, 116 are described in more detail below.

[0109] In some embodiments, the threshold speed is greater than 20 km / h. For example, greater than 25 km / h, greater than 30 km / h, greater than 35 km / h, or greater than 40 km / h. Known hydrostatic drives in hybrid transmissions are limited to speeds below 20 km / h, with a mechanical drive being used for speeds above 20 km / h. Since work vehicles must occasionally travel at speeds much higher than 20 km / h (e.g., when driving on the road), the mechanical drives in such transmissions utilize multiple gear ratios. For example, in known vehicles, the mechanical drive may have a first gear ratio optimized for speeds of 20-30 km / h, a second gear ratio optimized for speeds of 30-40 km / h, and a third gear ratio optimized for speeds above 40 km / h.However, it has been found that by setting a threshold speed for the hydrostatic drive mode greater than 20 km / h (e.g., greater than 25, 30, 35, or 40 km / h), good mechanical drive performance can be achieved with a fixed gear ratio instead. This allows a reduction in the number of components of the transmission 100, simplifying manufacturing and reducing costs.

[0110] As mentioned above, the first input member 104 and the output member 102 are spaced apart from each other by a distance D transverse to their respective rotational axes. In the illustrated embodiment, the distance D is at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm (e.g., about 340 mm).

[0111] As is apparent from the above description of the driveline assembly 20, the transmission 100 is configured for mounting in a driveline assembly 20 such that the first input member 104 is provided vertically above the output member 102 to provide a "long drop" configuration.

[0112] As mentioned above, the transmission 100 includes a first clutch device 114. The first clutch device 114 has an engaged state configured to connect the first input member 104 to the first drive path 108 when the transmission 100 is in the mechanical drive mode and a disengaged state configured to disconnect the first input member 104 from the first drive path 108 when the transmission 100 is in the hydrostatic drive mode. Likewise, the transmission 100 includes a second clutch device 116.The second clutch device 116 has an engaged state configured to connect the second input member 106 to the second drive path 110 when the transmission 100 is in the hydrostatic drive mode, and a disengaged state configured to disconnect the second input member 106 from the second drive path 110 when the transmission 100 is in the mechanical drive mode. The first and second clutch devices 114, 116 may be actuated to transition between the engaged and disengaged states using any suitable actuation means (e.g., hydraulic or electro-hydraulic actuators, electromechanical actuators, pneumatic actuators, electromagnetic actuators, or electric actuators).

[0113] The first drive path 108 includes a first input gear 118 configured for rotation with the first input member 104 when the transmission is in the mechanical drive mode. It should be understood that the first clutch device 114 couples the first input gear 118 to the first input member 104 for common rotation when the first clutch device 114 is in the engaged state.

[0114] The first drive path 108 also includes: an output gear 120 carried on the output member 102 for rotation with the output member 102; a first intermediate shaft 122 between the first input member 104 and the output member 102; and one or more intermediate gears 124 carried on the first intermediate shaft 122 for rotation with the first intermediate shaft 122. Each of the one or more intermediate gears 124 of the first intermediate shaft 122 always meshes with the first input gear 118 and / or the output gear 120.

[0115] In the illustrated embodiment, the one or more intermediate gears 124 of the first intermediate shaft 122 may include a single idler gear 124 that always meshes with both the first input gear 118 and the output gear 120. Such an idler gear 124 allows for increasing the distance between the first input gear 118 and the output gear 120 without affecting the fixed gear ratio. This is helpful for enabling the "long-drop" intermediate distance D described above.

[0116] How best in Fig. 7, the first input gear 118, the idler gear 124, and the output gear 120 are arranged in an approximately vertical line, with the idler gear 124 positioned below the first input gear 118 and the output gear 120 positioned below the idler gear 124. This is helpful in enabling the "long drop" pitch D described above.

[0117] The second drive path 110 includes a second input gear 126 configured for rotation with the second input member 106 when the transmission 100 is in the hydrostatic drive mode. It should be understood that the second clutch device 116 couples the second input gear 126 to the second input member 106 for common rotation when the second clutch device 116 is in the engaged state.

[0118] The second drive path 110 also includes: the output gear 120 carried on the output member 102 for rotation with the output member 102; a second intermediate shaft 128 between the second input gear 126 and the output gear 102; and one or more intermediate gears 130a, 130b carried on the second intermediate shaft 128 for rotation with the second intermediate shaft 128. Each of the one or more intermediate gears 130a, 130b of the second intermediate shaft 122 always meshes with the second input gear 126 and / or the output gear 120.

[0119] In the illustrated embodiment, the one or more intermediate gears 130a, 130b of the second intermediate shaft 128 include a first intermediate gear 130a that always meshes with the second input gear 126 and a second intermediate gear 130b that always meshes with the output gear 120. In this way, a gear ratio between the second input gear 126 and the output gear 120 can be set by selecting the number of teeth on the first and second intermediate gears 130a, 130b without having to change the size of the second input gear 126 or the output gear 120.

[0120] In the illustrated embodiment, the first intermediate gear 130a has more teeth than the second intermediate gear 130b. Thus, a gear ratio between the second input gear 126 and the output gear 120 can be influenced by the different number of teeth of the first and second intermediate gears 130a, 130b.

[0121] How best in Fig.7, the transmission has a V-shaped configuration, with the output member 102 located at a lower end of the V-shaped configuration, the first input member 104 and the first intermediate shaft 122 defining a first side of the V-shaped configuration, and the second input member 106 and the second intermediate shaft 128 defining a second side of the V-shaped configuration. Such a V-shaped configuration provides a package that can be easily reconfigured by removing one side of the V-shaped configuration. For example, in applications where only a hydrostatic drive mode is required, the first input member 104, the first input gear 118, the first intermediate shaft 122, and the idler gear 124 can simply be omitted, being located on a different side of the V-shaped configuration, without requiring any modification to the housing 132 of the transmission 100.

[0122] The one or more embodiments are described above merely by way of example, and it is understood that variations are possible without departing from the scope of the appended claims. It is also noted that, although the appended claims recite specific combinations of features described above, the scope of the present disclosure is not limited to the specific combinations claimed below, but is broad enough to include any combination of features disclosed herein.

Claims

[1] A transmission system for a work vehicle including a ground engaging structure, the transmission system comprising a hydraulic drive motor and a transmission comprising: an output member for driving the ground engaging structure; a first input member connectable to a drive unit, the transmission being operable to transmit drive from the first input member to the output member via a first drive path in a mechanical drive mode; and a second input member drivable by operation of the hydraulic drive motor, the transmission operable to transfer drive from the second input member to the output member via a second drive path in a hydrostatic drive mode; wherein the transmission is configured such that in the mechanical drive mode there is a fixed ratio of the speed of the first input member to the speed of the output member. [2] The transmission system of claim 1, further comprising a control system configured to place the transmission in the hydrostatic drive mode when the work vehicle is traveling at speeds below a threshold speed and to place the transmission in the mechanical drive mode when the work vehicle is traveling at speeds equal to or greater than the threshold speed. [3] Transmission system according to claim 2, wherein the threshold speed is more than 20 km / h, optionally more than 25 km / h, optionally more than 30 km / h, optionally more than 35 km / h, optionally more than 40 km / h. [4] A transmission system according to any preceding claim, wherein the first input member and the output member are spaced apart from each other at an intermediate distance transverse to their respective axes of rotation, the intermediate distance being at least 220 mm, optionally at least 240 mm, optionally at least 260 mm, optionally at least 280 mm, optionally at least 300 mm, optionally at least 320 mm, optionally at least 340 mm. [5] The transmission system of claim 4, wherein the transmission is configured for mounting in a driveline assembly such that the first input member is provided vertically above the output member. [6] A transmission system according to any preceding claim, wherein the transmission comprises a first side and a second side, wherein the first input member on the first side of the transmission is connectable to a drive unit and wherein the second input member on the first side of the transmission is connectable to the hydraulic drive motor. [7] A transmission system according to any preceding claim, wherein the transmission comprises a first clutch device having an engaged state configured to connect the first input member to the first drive path when the transmission is in the mechanical drive mode and a disengaged state configured to disconnect the first input member from the first drive path when the transmission is in the hydrostatic drive mode. [8] A transmission system according to any preceding claim, wherein the transmission comprises a second clutch device having an engaged state configured to connect the second input member to the second drive path when the transmission is in the hydrostatic drive mode and a disengaged state configured to disconnect the second input member from the second drive path when the transmission is in the mechanical drive mode. [9] A transmission system according to any preceding claim, wherein the first drive path comprises: a first input gear configured for rotation with the first input member when the transmission is in the mechanical drive mode, an output gear carried on the output member for rotation with the output member, a first intermediate shaft between the first input member and the output member, and one or more intermediate gears carried on the first intermediate shaft for rotation with the first intermediate shaft, each of the one or more intermediate gears of the first intermediate shaft always meshing with the first input gear and / or the output gear. [10] The transmission system of claim 9, wherein the one or more intermediate gears of the first intermediate shaft comprise a single idler gear that always meshes with both the first input gear and the output gear. [11] A transmission system according to claim 9 or 10, wherein the first input gear, the idler gear and the output gear are arranged in an approximately vertical line, the idler gear being positioned below the first input gear and the output gear being positioned below the idler gear. [12] A transmission system according to any preceding claim, wherein the second drive path comprises: a second input gear configured for rotation with the second input member when the transmission is in the hydrostatic drive mode, an output gear carried on the output member for rotation with the output member, a second intermediate shaft between the second input gear and the output gear, and one or more intermediate gears carried on the second intermediate shaft for rotation with the second intermediate shaft, each of the one or more intermediate gears of the second intermediate shaft always meshing with the second input gear and / or the output gear. [13] The transmission system of claim 12, wherein the one or more intermediate gears of the second intermediate shaft comprise a first intermediate gear that always meshes with the second input gear and a second intermediate gear that always meshes with the output gear. [14] A transmission system according to claim 13, wherein the first intermediate gear comprises more teeth than the second intermediate gear. [15] A transmission system according to claim 9 and 12, wherein the transmission comprises a V-shaped structure, wherein the output member is provided at a lower end of the V-shaped structure, the first input member and the first intermediate shaft define a first side of the V-shaped structure, and the second input member and the second intermediate shaft define a second side of the V-shaped structure. [16] A driveline assembly for a work vehicle including a ground engaging structure, the driveline assembly comprising: the transmission system according to any preceding claim; a drive unit configured to drive the first input member of the transmission; a hydraulic pump for supplying pressurized hydraulic fluid to drive the hydraulic drive motor, wherein the hydraulic pump is drivable by the drive unit; and one or more output drive shafts coupled to the output member of the transmission for driving the ground engaging structure of the work vehicle. [17] Drive train arrangement according to claim 16, wherein the hydraulic pump is a through-drive hydraulic pump positioned between the drive unit and the first input member of the transmission.

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