Power unit for a vehicle selected from a group of different vehicles and method for assembling the same

Abstract

Disclosed is a power train for a vehicle selected from a group of different vehicles. The power train includes an internal combustion engine and a continuously variable transmission (CVT) operatively connected to the engine. The CVT includes: a drive pulley operatively connected to the crankshaft of the engine, the drive pulley being rotatable about a drive pulley axis; a driven pulley rotatable about a driven pulley axis; a belt connecting the drive pulley to the driven pulley; and a housing at least partially enclosing the drive pulley, the driven pulley, and the belt. The power train further includes a sub-transmission selected from a group of different sub-transmissions according to the selected vehicle. The selected sub-transmission is mounted to the housing of the CVT. The housing of the CVT is configured to mount any of the group of different sub-transmissions. A method for assembling the power train is also provided.

Description

[0001] Cross-reference

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 893,901, filed Aug. 30, 2019, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present technology relates to a power unit for a vehicle and a method for assembling the same. Background Art

[0004] The powertrain of a vehicle is designed to meet the driving requirements of the vehicle, such as the torque requirement and the speed requirement of the vehicle. Thus, vehicles for different applications typically have different powertrains because their specific driving requirements may vary significantly. This can be particularly burdensome for vehicle manufacturers that manufacture different types of vehicles and thus must design and provide different powertrains for each type of vehicle. For example, a manufacturer may have to store a large number of components in order to be able to assemble any different powertrain depending on the vehicle being manufactured. Procuring and storing such a large number of components required to assemble different powertrains can be both expensive and complex for the manufacturer.

[0005] Accordingly, there is a need for a solution that addresses at least some of these drawbacks. Summary of the Invention

[0006] An object of the present technology is to improve at least some of the inconveniences existing in the prior art.

[0007] According to one aspect of the present technology, there is provided a power unit for a vehicle selected from a group of different vehicles. The power unit includes: an internal combustion engine; a continuously variable transmission (CVT) operatively connected to the engine; and a sub-transmission selected from a group of different sub-transmissions according to the selected vehicle in the group of different vehicles. The engine includes: a crankcase; a crankshaft disposed in the crankcase; and a cylinder block connected to the crankcase. The CVT includes: a drive pulley operatively connected to the crankshaft of the engine, the drive pulley being rotatable about a drive pulley axis; a driven pulley rotatable about a driven pulley axis; a belt connecting the drive pulley to the driven pulley; and a housing at least partially enclosing the drive pulley, the driven pulley, and the belt. The selected sub-transmission is mounted to the housing of the CVT. The housing of the CVT is configured to mount any of the group of different sub-transmissions.

[0008] In some embodiments, the housing of the CVT defines a plurality of mounting points for mounting a selected sub-transmission to the housing. At least some of the mounting points defined by the housing are for mounting any one of different sub-transmissions.

[0009] In some embodiments, all of the mounting points defined by the housing of the CVT are for mounting any one of different sub-transmissions.

[0010] In some embodiments, when the power unit is mounted on a selected vehicle, the driving pulley axis is vertically higher than the driven pulley axis.

[0011] In some embodiments, when the power unit is mounted on a selected vehicle, the driven pulley axis extends substantially laterally.

[0012] In some embodiments, at least a portion of the crankcase of the engine and at least a portion of a selected sub-transmission are disposed on the same side of the CVT.

[0013] In some embodiments, at least a portion of the selected sub-transmission extends laterally away from the CVT and passes by the engine.

[0014] In some embodiments, the selected sub-transmission includes an output shaft configured to be operatively connected to at least one ground engaging member of the vehicle. The output shaft is rotatable about an output shaft axis. The output shaft axis extends in a direction generally transverse to the driven pulley axis.

[0015] In some embodiments, when the power unit is mounted on a selected vehicle, the output shaft axis extends substantially longitudinally.

[0016] In some embodiments, the selected sub-transmission includes an output shaft configured to be operatively connected to at least one ground engaging member of the vehicle. The output shaft axis extends in a direction generally parallel to the driven pulley axis.

[0017] In some embodiments, when the power unit is mounted on a selected vehicle, the output shaft axis extends substantially laterally.

[0018] In some embodiments, the output shaft axis is vertically lower than the driven pulley axis.

[0019] In some embodiments, at least one sub-transmission of a set of different sub-transmissions includes: a sub-transmission housing; a plurality of gears enclosed within the sub-transmission housing; an input shaft operatively connected to the driven pulley of the CVT; a shifter for selectively engaging the input shaft with one of the plurality of gears; and an output shaft configured to be operatively connected to at least one ground engaging member of the vehicle. The output shaft is operatively connected to the input shaft via one of the plurality of gears.

[0020] In some embodiments, at least one sub-transmission of a set of different sub-transmissions includes: a sub-transmission housing; a plurality of gears enclosed within the sub-transmission housing; an input shaft operatively connected to the driven pulley of the CVT, the input shaft being drivingly engaged with the plurality of gears; and an output shaft extending laterally outwardly from a first lateral side and a second lateral side of the sub-transmission housing.

[0021] In some embodiments, a set of different sub-transmissions includes a first sub-transmission, a second sub-transmission, and a third sub-transmission. The first sub-transmission includes: an input shaft operatively connected to the driven pulley of the CVT; a plurality of gears; and an output shaft operatively connected to the input shaft via the plurality of gears, the output shaft being rotatable about a laterally extending output shaft axis, each of a first end portion and a second end portion of the output shaft being configured to be operatively connected to a respective ground engaging member of a selected vehicle. The second sub-transmission includes: an input shaft operatively connected to the driven pulley of the CVT; a plurality of gears; and an output sprocket operatively connected to the input shaft via the plurality of gears, the output sprocket being configured to be operatively connected to a ground engaging member of a selected vehicle for driving the selected vehicle. The third sub-transmission includes: an input shaft operatively connected to the driven pulley of the CVT; a plurality of gears; and a first output member and a second output member operatively connected to each other and driven by the input shaft via the plurality of gears, the first output member and the second output member being disposed on opposite sides of the third sub-transmission, the first output member and the second output member being rotatable about respective axes extending generally longitudinally.

[0022] In some embodiments, the second sub-transmission further includes a sub-transmission housing that encloses the plurality of gears within the sub-transmission housing. The output sprocket is positioned outside the sub-transmission housing.

[0023] In some embodiments, the engine defines a plurality of engine mounts for mounting the engine to a frame of a selected vehicle. For at least some vehicles of a different group of vehicles, only some of the engine mounts are used to mount the engine to the frame.

[0024] In some embodiments, a selected sub-transmission defines additional vehicle mounts for mounting the power unit to a frame of a selected vehicle.

[0025] In some embodiments, at least one sub-transmission of a different group of sub-transmissions includes a sub-transmission housing. The sub-transmission housing defines an internal space of the at least one sub-transmission. The sub-transmission housing is sealed such that the internal space of the at least one sub-transmission is not accessible without disassembling the sub-transmission housing.

[0026] In some embodiments, at least one sub-transmission of a different group of sub-transmissions includes a sub-transmission housing. The sub-transmission housing defines an internal space of the at least one sub-transmission. When the selected sub-transmission is one of the at least one sub-transmissions, the sub-transmission housing of the at least one sub-transmission is sealed relative to the housing of the CVT.

[0027] In some embodiments, at least one sub-transmission of a different group of sub-transmissions includes a reverse gear. When the selected sub-transmission is the at least one sub-transmission including the reverse gear, the power unit is operable to drive the vehicle in reverse via engagement of the reverse gear.

[0028] In some embodiments, the housing of the CVT defines an air inlet and an air outlet; and the air inlet and the air outlet are always in the same position regardless of the selected sub-transmission.

[0029] In some embodiments, the engine is a single-cylinder engine.

[0030] According to another aspect of the present technology, there is provided a method for assembling a power unit for a vehicle selected from a different group of vehicles. The method includes: providing an engine and a continuously variable transmission (CVT) operatively connected to the engine; determining the selected vehicle for which the power unit is to be provided; selecting a sub-transmission from a different group of sub-transmissions based on the selected vehicle for which the power unit is to be provided; and mounting the selected sub-transmission to the housing of the CVT, the housing of the CVT being configured to mount any of the different group of sub-transmissions.

[0031] In some embodiments, for any one of the different sub - transmissions being the selected sub - transmission, installing the selected sub - transmission includes: fastening the selected sub - transmission to all of a plurality of mounting points defined by the housing of the CVT for mounting the selected sub - transmission.

[0032] In some embodiments, for at least one of the different sub - transmissions being the selected sub - transmission, installing the selected sub - transmission includes: positioning the selected sub - transmission such that the axis of the output shaft of the selected sub - transmission extends in a direction generally transverse to the axis of the driven pulley of the CVT.

[0033] In some embodiments, for at least one of the different sub - transmissions being the selected sub - transmission, installing the selected sub - transmission includes: positioning the selected sub - transmission such that the axis of the output shaft of the selected sub - transmission extends in a direction generally parallel to the axis of the driven pulley of the CVT.

[0034] According to another aspect of the present technology, there is provided a gear set for a powertrain of a vehicle. The gear assembly includes: a first shaft that rotates about a first shaft axis; a second shaft that is operatively connected to the first shaft and rotates about a second shaft axis extending parallel to the first shaft axis; a first gear that is mounted to the first shaft, the first gear being a free - wheel clutch gear; a second gear that is fixedly mounted to the first shaft for rotation with the first shaft; a third gear that is mounted to the second shaft, the third gear being a free - wheel clutch gear, the third gear being drivingly engaged with the second gear; and a fourth gear that is fixedly mounted to the second shaft for rotation with the second shaft, the fourth gear being drivingly engaged with the first gear. When the rotational speed of the first shaft is greater than the rotational speed of the second shaft, the first shaft drives the second shaft via the driving engagement between the second gear and the third gear, and the first gear overruns. When the rotational speed of the second shaft is greater than the rotational speed of the first shaft, the second shaft drives the first shaft via the driving engagement between the fourth gear and the first gear, and the third gear overruns.

[0035] In some embodiments, each of the first gear and the third gear includes: an inner race that is mounted to a corresponding one of the first shaft and the second shaft; an outer race that is disposed radially outside the inner race, the outer race including a plurality of gear teeth; and a clutch adapter that is disposed between the inner race and the outer race, the gear overrunning when the clutch adapter disengages the outer race from the inner race such that the inner race rotates relative to the outer race.

[0036] In some embodiments, the clutch adapter includes a plurality of rollers that selectively couple the rotation of the outer race and the inner race.

[0037] In some embodiments, the first gear and the fourth gear rotate in opposite directions relative to each other; and the second gear and the fourth gear rotate in opposite directions relative to each other.

[0038] In some embodiments, the first gear meshes with the fourth gear; and the second gear meshes with the third gear.

[0039] In some embodiments, the first gear and the second gear are adjacent to each other; and the third gear and the fourth gear are adjacent to each other.

[0040] In some embodiments, the first shaft is configured to be connected to an electric motor; and the second shaft is configured to be connected to a transmission of a vehicle's powertrain.

[0041] In some embodiments, the gear assembly further includes a sprocket mounted to the second shaft for rotation therewith, the sprocket being configured to be connected to a transmission of a vehicle's powertrain.

[0042] In some embodiments, the diameter of the first gear is greater than the diameter of the fourth gear; and the diameter of the third gear is greater than the diameter of the second gear.

[0043] In some embodiments, the second gear and the fourth gear are spur gears.

[0044] According to another aspect of the present technology, there is provided a power unit for a vehicle. The power unit includes an internal combustion engine, a continuously variable transmission (CVT), an electric motor module, and a sub-transmission. The internal combustion engine includes: a crankcase; a crankshaft disposed in the crankcase; and a cylinder block connected to the crankcase. The CVT is operatively connected to the engine and includes: a drive pulley operatively connected to the crankshaft of the engine, the drive pulley being rotatable about a drive pulley axis; a driven pulley rotatable about a driven pulley axis; a belt connecting the drive pulley to the driven pulley; and a housing at least partially enclosing the drive pulley, the driven pulley, and the belt. The electric motor module is operatively connected to the CVT and includes: an electric motor having a motor shaft rotatable about a motor shaft axis; a gear assembly operatively connected to the motor shaft; and a drive connecting shaft operatively connected between the driven pulley of the CVT and the gear assembly. The motor shaft can be selectively operated to drive the drive connecting shaft via the gear assembly and can be selectively operated to be driven by the drive connecting shaft via the gear assembly. The sub-transmission is operatively connected to the drive connecting shaft of the electric motor module and includes an output shaft configured to be operatively connected to at least one ground engaging member of the vehicle.

[0045] In some embodiments, the power unit further includes a controller that is operable to control the operation of the electric motor module in a plurality of modes, the plurality of modes including: an engine drive mode, in which the torque generated by the electric motor is zero and the output shaft of the sub-transmission is driven by the torque transmitted from the engine to the output shaft of the sub-transmission via the CVT and the drive connection shaft; an electric motor drive mode, in which the output shaft of the sub-transmission is driven by the torque transmitted from the electric motor to the output shaft of the sub-transmission via the gear assembly and the drive connection shaft, and the driven pulley of the CVT is disengaged from the drive engagement with the output shaft of the sub-transmission and the drive connection shaft of the electric motor module; and a hybrid drive mode, in which the output shaft of the sub-transmission is driven by the torque transmitted to the output shaft of the sub-transmission through both the motor shaft of the electric motor and the driven pulley of the CVT.

[0046] In some embodiments, in the engine drive mode, the drive connection shaft of the electric motor module transmits torque to the motor shaft via the gear assembly, and the electric motor operates as a generator.

[0047] In some embodiments, the power unit further includes a centrifugal clutch that is operatively connected between the driven pulley of the CVT and the drive connection shaft of the electric motor module.

[0048] In some embodiments, the centrifugal clutch operates in one of an open position and a closed position based on the rotational speed of the driven pulley of the CVT; and when the electric motor module operates in the electric motor drive mode, the centrifugal clutch is in the open position.

[0049] In some embodiments, the electric motor module further includes a housing that at least partially encloses the gear assembly and the motor shaft; and the housing of the electric motor module is mounted to the housing of the CVT.

[0050] In some embodiments, the housing of the electric motor module defines a plurality of mounting points; and the sub-transmission is mounted to the housing of the motor module via at least some of the mounting points thus defined.

[0051] In some embodiments, the housing of the CVT defines a plurality of mounting points for mounting the electric motor module to the housing of the CVT; and the mounting points of the housing of the CVT are aligned with the mounting points of the housing of the electric motor module.

[0052] In some embodiments, the power unit further includes a centrifugal clutch that is operatively connected between the driven pulley of the CVT and the drive connection shaft of the electric motor module, and the housing of the CVT at least partially encloses the centrifugal clutch within the housing of the CVT.

[0053] In some embodiments, when the power unit is installed on a vehicle, the motor shaft axis extends substantially laterally.

[0054] In some embodiments, the driven pulley axis extends substantially parallel to the motor shaft axis.

[0055] In some embodiments, the drive connection shaft of the electric motor module is laterally disposed between the CVT and the sub-transmission.

[0056] In some embodiments, the sub-transmission includes: a sub-transmission housing; a plurality of gears enclosed within the sub-transmission housing; a transmission input shaft operatively connected between the drive connection shaft and the output shaft of the electric motor module; and a shifter for selectively engaging the transmission input shaft with one of the plurality of gears, and the output shaft is operatively connected to the transmission input shaft via one of the plurality of gears.

[0057] In some embodiments, the gear assembly includes: a first shaft that rotates about a first shaft axis; a second shaft operatively connected to the first shaft and rotating about a second shaft axis extending parallel to the first shaft axis; a first gear mounted to the first shaft, the first gear being a freewheel clutch gear; a second gear fixedly mounted to the first shaft for rotation therewith; a third gear mounted to the second shaft, the third gear being a freewheel clutch gear and drivingly engaged with the second gear; and a fourth gear fixedly mounted to the second shaft for rotation therewith and drivingly engaged with the first gear. When the rotational speed of the first shaft is greater than the rotational speed of the second shaft, the first shaft drives the second shaft via the driving engagement between the second gear and the third gear, and the first gear overruns. When the rotational speed of the second shaft is greater than the rotational speed of the first shaft, the second shaft drives the first shaft via the driving engagement between the fourth gear and the first gear, and the third gear overruns.

[0058] In some embodiments, the first shaft is operatively connected to the motor shaft, and the first shaft axis is coaxial with the motor shaft axis.

[0059] In some embodiments, each of the first gear and the third gear includes: an inner ring mounted to a corresponding one of the first shaft and the second shaft; an outer ring disposed radially outward of the inner ring, the outer ring including a plurality of gear teeth; and a clutch adapter disposed between the inner ring and the outer ring, and the gear overruns when the clutch adapter disengages the outer ring from the inner ring, such that the inner ring rotates relative to the outer ring.

[0060] In some embodiments, the clutch adapter includes a plurality of rollers that selectively couple the rotation of the outer ring and the inner ring.

[0061] In some embodiments, the first gear and the fourth gear rotate in opposite directions relative to each other; and the second gear and the fourth gear rotate in opposite directions relative to each other.

[0062] In some embodiments, the first gear meshes with the fourth gear; and the second gear meshes with the third gear.

[0063] In some embodiments, the first gear and the second gear are adjacent to each other; and the third gear and the fourth gear are adjacent to each other.

[0064] In some embodiments, the diameter of the first gear is greater than the diameter of the fourth gear; and the diameter of the third gear is greater than the diameter of the second gear.

[0065] In some embodiments, the second gear and the fourth gear are spur gears.

[0066] In some embodiments, the electric motor module further includes a belt drive operatively connected between the gear assembly and the drive connection shaft.

[0067] In some embodiments, a first shaft is operatively connected to the motor shaft; a second shaft is operatively connected to the belt drive; and the belt drive operatively connects the gear assembly to the drive connection shaft.

[0068] In some embodiments, the belt drive assembly includes a sprocket mounted to the second shaft for rotation therewith.

[0069] For the purposes of the present application, when referring to vehicle orientation and the positioning of vehicle components, terms related to spatial orientation such as forward, backward, left, and right are understood as commonly understood by a vehicle driver sitting in the vehicle in a normal driving position.

[0070] Embodiments of the present technology each have at least one of the aspects mentioned above, but do not necessarily have all of these aspects.

[0071] Additional and / or alternative features, aspects, and advantages of embodiments of the present technology will become apparent from the following description, the drawings, and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] For a better understanding of the present technology and other aspects and further features thereof, reference is made to the following description taken in conjunction with the drawings, in which:

[0073] Figure 1 is a perspective view of a portion of a power unit for a vehicle, viewed from the right rear side, including an engine and a continuously variable transmission (CVT) in a disassembled configuration;

[0074] Figure 2 is Figure 1 a top plan view of an exploded configuration of an engine and a CVT;

[0075] Figure 3 is Figure 1 a left side view of an engine and a CVT in an assembled configuration;

[0076] Figure 4 is Figure 3 a front view of an engine and a CVT;

[0077] Figure 5 is Figure 1 a perspective view of a power unit including an engine, a CVT, and a first sub - transmission selected from a group of different sub - transmissions in an exploded configuration;

[0078] Figure 6 from Figure 5 a perspective view of the first sub - transmission observed from the right rear side;

[0079] Figure 7 is Figure 5 a left side view of the first sub - transmission;

[0080] Figure 8 is Figure 5 a right side view of the first sub - transmission;

[0081] Figure 9 is Figure 5 a top plan view of the first sub - transmission;

[0082] Figure 10 is Figure 5 a rear view of the power unit in an assembled configuration;

[0083] Figure 11 is Figure 10 a front view of the power unit;

[0084] Figure 12 is Figure 10 a left side view of the power unit;

[0085] Figure 13 is Figure 10 a right side view of the power unit;

[0086] Figure 14 is Figure 1 a perspective view of the power unit including an engine, a CVT, and a second sub - transmission selected from the group of different sub - transmissions in an exploded configuration;

[0087] Figure 15 is from Figure 14 a perspective view of the second sub - transmission observed from the left rear side;

[0088] Figure 16 is a perspective view observed from the right rear side of the second sub-transmission of Figure 15 ;

[0089] Figure 17 is Figure 15 the left side view of the second sub-transmission of

[0090] Figure 18 is Figure 15 the top plan view of the second sub-transmission of

[0091] Figure 19 is Figure 14 the rear view of the power unit of

[0092] Figure 20 is Figure 19 the left side view of the power unit of

[0093] Figure 21 is Figure 19 the right side view of the power unit of

[0094] Figure 22 is Figure 19 the top plan view of the power unit of

[0095] Figure 23 is Figure 1 the perspective view of the power unit of , which includes an engine, a CVT and a third sub-transmission selected from the group of different sub-transmissions in a disassembled configuration;

[0096] Figure 24 is Figure 23 the rear view of the third sub-transmission of

[0097] Figure 25 is Figure 24 the front view of the third sub-transmission of

[0098] Figure 26 is Figure 24 the left side view of the third sub-transmission of

[0099] Figure 27 is Figure 23 the rear view of the power unit of

[0100] Figure 28 is Figure 27 the front view of the power unit of

[0101] Figure 29 is Figure 27 the left side view of the power unit of

[0102] Figure 30 is Figure 27Right side view of the power unit;

[0103] Figure 31 is Figure 27 Top plan view of the power unit;

[0104] Figure 32 Isometric view of a part of the power unit according to another embodiment of the present technology, viewed from the right rear side, wherein the power unit includes an engine, a CVT, a first sub-transmission, and an electric motor module;

[0105] Figure 33 is Figure 32 Partially exploded isometric view of the power unit;

[0106] Figure 34 Is viewed from the left rear side Figure 32 Partially exploded isometric view of the electric motor module;

[0107] Figure 35 Is viewed from the right rear side Figure 32 Partially exploded isometric view of the electric motor module;

[0108] Figure 36 Is viewed from the left rear side Figure 32 Isometric view of the drive assembly of the electric motor module;

[0109] Figure 37 is Figure 36 Isometric view of the drive assembly, which shows a cross-section taken through the gear assembly of the drive assembly;

[0110] Figure 38 is Figure 37 Cross-sectional view of a part of the freewheel clutch gear of the gear assembly;

[0111] Figure 39 is Figure 32 Schematic diagram of the electric motor module and the corresponding controller;

[0112] Figure 40 Isometric view of a part of the power unit according to another embodiment, viewed from the right rear side, wherein the power unit includes an engine, a CVT, an electric motor module, and a second sub-transmission; and

[0113] Figure 41 Isometric view of a part of the power unit according to another embodiment, viewed from the right rear side, wherein the power unit includes an engine, a CVT, an electric motor module, and a third sub-transmission. Detailed Description

[0114] According to the present technology, a power pack 100 is provided which, by switching modular components of the power pack 100, can be used in any vehicle selected from a predefined group of different vehicles having different drive requirements. For example, the predefined group of vehicles can include all-terrain vehicles (ATVs), snowmobiles, and road vehicles, all of which are driven in different ways.

[0115] Referring Figure 1 , the power pack 100 includes an internal combustion engine 10 which is configured to be supported by the frame of the vehicle to which the power pack 100 is to be installed. In this embodiment, the engine 10 operates on a two-stroke engine cycle such that the engine 10 completes a power cycle through two strokes (upstroke and downstroke) of an engine piston (not shown). Accordingly, the engine 10 can be referred to as a two-stroke engine. It is contemplated that in other embodiments, the engine 10 can be a four-stroke engine. Referring Figure 3 , the engine 10 has a crankcase 12, a cylinder block 14 defining a single cylinder (not shown) connected to the top of the crankcase 12, and a cylinder head 19 connected to the top of the cylinder block 14. The engine 10 also has a crankshaft (not shown) disposed in the crankcase 12 and driven by the movement of the piston. An engine exhaust duct 55 for the discharge of exhaust gases extends rearwardly from the engine 10.

[0116] As Figure 3 and Figure 4 shown, in order to mount the engine 10 to a selected vehicle to which the power pack 100 is to be installed, the engine 10 defines a plurality of engine mounts 60 for mounting the engine 10 to the frame of the vehicle. In this embodiment, each of the engine mounts 60 includes an opening 61 for inserting a corresponding protruding mounting member of the frame of the vehicle therein. Depending on the vehicle for which the power pack 100 is to be provided, only one of the engine mounts 60 can be used to mount the engine 10 to the frame of the selected vehicle.

[0117] Although in this embodiment the engine 10 is a single-cylinder engine having a single cylinder and a single piston movable therein, it is contemplated that in other embodiments, the engine 10 can be a twin-cylinder engine.

[0118] It is conceivable that, in some embodiments, the engine 10 may have an electronic reverse function for reversing the operation of the engine 10 such that the crankshaft can be selectively rotated in the forward rotation direction and the reverse rotation direction. This can be achieved by controlling fuel injection and ignition within the cylinders of the engine 10. For example, U.S. Patent No. 5,036,802, issued on August 6, 1991, describes in detail a manner in which such an electronic reverse function can be implemented, and the entire content of this U.S. patent is incorporated herein by reference. The electronic reverse function can be selectively enabled via an electronic reverse function control element (e.g., a button) provided on the vehicle on which the power unit 100 is to be installed.

[0119] As Figure 1 , Figure 2 and Figure 4 shown, the generator 56 is connected to the side of the crankcase 12 opposite to the power output side. The generator 56 uses the power generated by the engine 10 to generate electrical energy for storage in a battery (not shown). The electric starter motor 58 is also connected to the front of the crankcase 12. The starter motor 58 selectively engages the crankshaft via a gear (not shown) to rotate the crankshaft before the engine 10 can run on its own due to the internal combustion process, thereby starting the engine 10.

[0120] The power unit 100 further includes a continuously variable transmission (CVT) 40, to which the engine 10 is operatively connected. The CVT 40 includes a drive pulley 42 operatively connected to the crankshaft of the engine 10, a driven pulley 44, and a drive belt 46 disposed around both the pulleys 42, 44 to transmit torque from the drive pulley 42 to the driven pulley 44. In particular, as Figure 2 shown, the drive pulley 42 is operatively connected to the crankshaft of the engine 10 via the output shaft 16 of the engine 10, and the output shaft 16 rotates about a laterally extending axis 17 when the power unit 100 is installed on the vehicle 10. Notably, the drive pulley 42 is mounted to the output shaft 16 such that the drive pulley 42 can rotate about the axis 17. Thus, the axis 17 can be referred to as the "drive pulley axis". The driven pulley 44 rotates about an axis 67 defined by an intermediate shaft 51, which extends parallel to the axis 17 (i.e., generally laterally when the power unit 100 is installed on the selected vehicle). Thus, the axis 67 can be referred to as the "driven pulley axis". As will be explained below, the driven pulley 44 is operatively connected to the intermediate shaft 51 via a centrifugal clutch 65. The driven pulley 44 is located behind and above the drive pulley 42 such that the driven pulley axis 67 is located behind and above the drive pulley axis 17, as Figure 3 shown.

[0121] Each of the pulleys 42, 44 includes a movable sheave that can axially move relative to a fixed sheave to change the effective diameter of the corresponding pulley 42, 44. The drive pulley 42 is a centrifugal pulley because its sheave moves in response to centrifugal force applied thereto. The effective diameters of the pulleys 42, 44 are in an inverse relationship. In the illustrated embodiment, the CVT 40 is a pure mechanical CVT 40 in which the diameter of the driven pulley 44 increases as the rotational speed of the drive pulley 42 increases (i.e., as the engine speed increases). Thus, when the torque required at the intermediate shaft 51 increases, the diameter of the driven pulley 44 decreases. Accordingly, the CVT 40 can be referred to as a "non-assisted" CVT because the transmission ratio of the CVT 40 (i.e., the ratio of the effective diameter of the driven pulley 44 to the effective diameter of the drive pulley 42) is automatically mechanically adjusted according to the speed of the engine 10 and the torque demand at the intermediate shaft 51.

[0122] It is contemplated that in other embodiments, the CVT 40 can be an assisted CVT, such as a hydraulic CVT.

[0123] Continuing to refer to Figure 1 and Figure 2, the driven pulley 44 is operatively connected to the input portion of a centrifugal clutch 65 disposed adjacent the driven pulley 44. As shown, the centrifugal clutch 65 is coaxial with the driven pulley 44. The centrifugal clutch 65 has a clutch housing 68 and an outer coupler 69 that rotates with the clutch housing 68. In this embodiment, the outer coupler 69 has an internal spline (not shown) for receiving and drivingly engaging the intermediate shaft 51. The centrifugal clutch 65 also has clutch shoes (not shown) enclosed within the clutch housing 68. The centrifugal clutch 65 operates in one of an open position and a closed position based on the rotational speed of the driven pulley 44 of the CVT 40. When the centrifugal force applied to the clutch shoes overcomes the resistance generated by a set of springs (not shown) holding the clutch shoes, the centrifugal clutch 65 begins to operate in the closed position at a given rotational speed - at which the clutch shoes drive the clutch housing 68 - such that the clutch shoes frictionally engage the inner side of the clutch housing 68. The manner of operation of the centrifugal clutch is known in the art and thus will not be described in detail herein. In this embodiment, when the rotational speed of the intermediate shaft 51 reaches a speed of approximately between 2000 rpm and 3000 rpm inclusive of the end values, the centrifugal clutch 65 begins to operate in the closed position (i.e., the clutch housing 68 and the outer coupler 69 rotate). Thus, in this embodiment, when the engine 10 is running at idle, the centrifugal clutch 65 is in the open position such that the outer coupler 69 is not driven by the driven pulley 44. In other embodiments, the centrifugal clutch 65 may transition from the open position to the closed position at a different rotational speed.

[0124] The CVT housing 48 encloses the drive pulley 42, the driven pulley 44, the drive belt 46, and the centrifugal clutch 65 therein. It is noted that the CVT housing 48 has a left portion 50 and a right portion 52 that are fixed to each other via a plurality of fasteners. The outer coupler 69 of the centrifugal clutch 65 is operatively connected to the output coupler 54 via the intermediate shaft 51 ( Figure 1 ). It is noted that in this embodiment, the output coupler 54 is defined by the right end portion of the intermediate shaft 51. As can be observed, the output coupler 54 is rotatably connected to the right portion 52 of the CVT housing 48. Thus, when the centrifugal clutch 65 is closed, the outer coupler 69 drives the output coupler 54. As will be described in more detail below, the output coupler 54 is accessible on the right side of the power unit 100 to allow for driving engagement with the driven pulley 44.

[0125] As Figure 1 and Figure 4As shown, the right side portion 52 of the CVT housing 48 defines an air inlet 45 and an air outlet 47 for receiving and discharging air from the CVT housing 48, respectively. The air circulation through the air inlet 45 and the air outlet 47 allows for cooling of the CVT components, namely the belt 46 that may deteriorate in the case of overheating. In this embodiment, the air inlet 45 faces upward while the air outlet 47 faces forward.

[0126] The CVT housing 48 also has a plurality of mounts 64 for mounting a sub-transmission to the CVT housing 48 1 -64 4 . Thus, the mounts 64 1 -64 4 may be referred to as "sub-transmission mounts". Each of the sub-transmission mounts 64 1 -64 4 thus defines a corresponding mounting point for mounting the sub-transmission. In particular, in this embodiment, each sub-transmission mount 64 1 -64 4 is an internally threaded opening defined by the CVT housing 48. In this embodiment, the right side portion 52 of the CVT housing 48 defines the sub-transmission mounts 64 1 -64 4 such that the sub-transmission is mounted to the right side of the CVT housing 48. As will be described in more detail below, the configuration of the sub-transmission mounts 64 1 -64 4 allows for any selected sub-transmission from a group of different sub-transmissions to be mounted to the CVT housing 48.

[0127] In order for the power unit 100 to be used in any vehicle from a predefined group of different vehicles, the power unit 100 is provided with a sub-transmission selected from a predefined group of different sub-transmissions 110, 210, 310, depending on the vehicle for which the power unit 100 is to be provided. In other words, each sub-transmission 110, 210, 310 is associated with a corresponding vehicle from a group of different vehicles, and thus by providing a selected one of the sub-transmissions 110, 210, 310 to the power unit 100, the power unit 100 can be used in the vehicles corresponding to the sub-transmissions 110, 210, 310. In this embodiment, the sub-transmissions 110, 210, 310 correspond to a snowmobile, a road vehicle, and an all-terrain vehicle (ATV), respectively. Thus, the sub-transmissions 110, 210, 310 will be referred to as the "snowmobile sub-transmission" 110, the "road vehicle sub-transmission" 210, and the "ATV sub-transmission" 310. The configuration of the sub-transmissions 110, 210, 310 and the corresponding implementation with respect to the power unit 100 will be described in more detail below.

[0128] It should be understood that the predefined groups of vehicles are not limited to snowmobiles, road vehicles, and ATVs, and the power unit 100 can be provided for other vehicles that require corresponding drive outputs. Thus, the terms "snowmobile sub-transmission", "road vehicle sub-transmission", and "ATV sub-transmission" used herein are for differentiating the sub-transmissions from each other and identifying a possible intended use, and are not intended to limit the use of these sub-transmissions to a single type of vehicle.

[0129] Power unit for a snowmobile

[0130] Referring Figure 5 , in one potential configuration, the power unit 100 is configured for a snowmobile and thus the snowmobile sub-transmission 110 is selected from the sub-transmissions 110, 210, 310 as part of the power unit 100. For example, an example of a snowmobile for which the power unit 100 can be provided in this configuration can be found in U.S. Patent No. 9,114,852, issued on August 25, 2015, the entire content of which is incorporated herein by reference. The snowmobile sub-transmission 110 is configured to be operatively connected between the CVT 40 and the ground engaging member (i.e., drive track) of the snowmobile for driving the snowmobile.

[0131] Now referring Figures 6 to 9 the snowmobile sub-transmission 110 will be described. The snowmobile sub-transmission 110 has a sub-transmission housing 112 that defines the internal space of the snowmobile sub-transmission 110 and encloses a plurality of gears 150 therein (schematically shown in Figure 7 ). It is noted that the sub-transmission housing 112 has a right side portion 111 and a left side portion 113, and the right side portion 111 and the left side portion 113 are fastened to each other to enclose the gears 150 and other components therein. The attachment of the portions 111, 113 of the sub-transmission housing 112 seals the snowmobile sub-transmission such that the internal space of the snowmobile sub-transmission is not accessible without disassembling the sub-transmission housing 112.

[0132] The lubrication inlet 148 extends upward from the top portion of the sub-transmission housing 112 for lubricating the drive train of the snowmobile sub-transmission 110.

[0133] As Figure 7 and Figure 9 shown, the snowmobile sub-transmission 110 has an input shaft 118 that extends outward from the sub-transmission housing 112 at the left side 117 of the snowmobile sub-transmission 110. The input shaft 118 is configured to be received by the output coupler 54 such that the CVT 40 and the snowmobile sub-transmission 110 are drivingly engaged. It is noted that the input shaft 118 and the output coupler 54 are splined and are thus drivingly connected. Thus, in use, the input shaft 118 rotates about the driven pulley axis 67.

[0134] Gear 150 operably connects the input shaft 118 to the output shaft 120 of the snow vehicle transmission 110. The output shaft 120 is rotatable about an output shaft axis 125 that extends generally parallel to the driven pulley axis 67 such that when the power pack 100 is mounted on a snow vehicle, the output shaft axis 125 extends generally laterally. The output shaft 120 is configured to operably connect to the drive track of the snow vehicle. As can be observed, the output shaft 120 has two drive portions 121, 123 for driving respective drive sprockets of the snow vehicle, and the drive sprockets in turn engage the drive track of the snow vehicle to propel the snow vehicle. As Figure 6 shown, the output shaft 120 extends laterally outwardly from two lateral sides of the sub-transmission housing 112.

[0135] As Figure 7 and Figure 9 shown, for connection to the CVT 40, the snow vehicle transmission 110 has a plurality of mounting connectors 145 1 -145 4 , and the plurality of mounting connectors 145 1 -145 4 are configured to engage sub-transmission mounts 64 1 -64 4 of the CVT housing 48. It is noted that in this embodiment, each of the mounting connectors 145 1 -145 4 is a fastener that extends through two portions 111, 113 of the sub-transmission housing 112 to threadedly engage a corresponding one of the sub-transmission mounts 64 1 -64 4 .

[0136] With particular reference to Figure 9 , the snow vehicle transmission 110 defines two shaft mounting portions 127, 129, and in addition to the vehicle mounts 60 of the engine 10, the power pack 100 can also be mounted to the snow vehicle through the two shaft mounting portions 127, 129. In particular, the shaft mounting portions 127, 129 are portions of the output shaft 120 configured to be supported by the frame of the snow vehicle via bearings 135 (schematically shown in Figure 9 ). For example, in use, the shaft mounting portions 127, 129 of the snow vehicle transmission 110 will be supported by the tunnel of the snow vehicle via bearings 135.

[0137] The snowmobile transmission 110 also has a shifter 140 including a shifter lever for selectively engaging the input shaft 118 with one of the gears 150. More specifically, in use, the shifter 140 can be operated by the snowmobile user to engage the gears of the sub-transmission 110 so as to change the drive operation of the output shaft 120. Notably, the shifter 140 allows the user to operate the snowmobile transmission 110 in one of a plurality of "gear positions", which in this embodiment include high gear, low gear, neutral, and reverse. Notably, specific ones of the gears 150 are associated with high gear, low gear, and reverse such that when engaged via the shifter 140, the snowmobile is driven in high gear, low gear, and reverse, respectively.

[0138] It is contemplated that in other embodiments, the snowmobile transmission 110 can be operated in a different number of gear positions.

[0139] The power pack 100 including the snowmobile transmission 110 is shown assembled in Figures 10 to 13 As can be observed, the power pack 100 is configured such that the crankcase 12 of the engine 10 and a portion of the snowmobile transmission 110 are disposed on the right side of the CVT 40. Notably, as Figure 10 shown, a portion of the snowmobile transmission 110 extends laterally away from the CVT 40 (i.e., toward the right side) past the engine 10. For example, in this embodiment, the sub-transmission housing 112 and a portion of the output shaft 120 extend laterally away from the CVT 40 past the engine 10. Further, with reference to Figure 10 and Figure 12 , the output shaft 120 of the snowmobile transmission 110 is positioned relatively low. For example, the output shaft axis 125 of the output shaft 120 is vertically lower than the driven pulley axis 67.

[0140] Additionally, as can be observed, all of the mounting points defined by the sub-transmission mounts 64 of the CVT housing 48 1 -64 4 are used to mount the snowmobile transmission 110 to the CVT housing 48. That is, each of the sub-transmission mounts 64 of the CVT housing 48 1 -64 4 receives a corresponding one of the mount connectors 145 1 -145 4 therein.

[0141] The snow vehicle transmission 110 is a modular unit of the power pack 100 that is attached to the CVT 40 but is otherwise spatially independent of the CVT 40. Notably, the internal space of the snow vehicle transmission 110, as defined by the sub-transmission housing 112, is sealed relative to the CVT housing 48. Thus, the air flow within the CVT housing 48 is independent of the snow vehicle transmission 110. In other words, the air flow entering the CVT housing 48 (via the air inlet 45) does not enter the internal space of the snow vehicle transmission 110.

[0142] It should be understood that this particular configuration of the power pack 100 is not limited to use with snow vehicles, but can alternatively be used in other vehicles driven by two laterally extending drive portions 121, 123.

[0143] Referring Figure 32 and Figure 33 , in some embodiments, the power pack 100 further includes an electric motor module 400 operatively connected between the CVT 40 and the snow vehicle transmission 110. The electric motor module 400 includes an electric motor 410 and a drive assembly 412 operatively connected to the electric motor 410 ( Figure 34 , Figure 35 ).

[0144] Referring Figure 34 and Figure 35 , the drive assembly 412 is enclosed by a housing 414 that includes a right portion 420, a middle portion 422, and a left portion 426. The right portion 420 and the middle portion 422 of the housing 414 extend vertically lower than the left portion 426 and are connected to each other by fasteners received in respective openings 423 in each of the right portion 420 and the middle portion 422. Additionally, the right portion 420 of the housing 414 is connected to the motor housing 411 that encloses the motor 410. The housing 414 is mounted to the CVT housing 48 on its right side. Notably, each of the right portion 420 and the middle portion 422 of the housing 414 has a plurality of mounts 427 for mounting the housing 414 of the electric motor module 400 to the CVT housing 48. Notably, the mounts 427 of the right portion 420 are aligned with the mounts 427 of the middle portion 422 to define a plurality of mounting points of the housing 414. The mounting points of the housing 414 are aligned with the mounting points defined by the mounts 64 1 -64 4 of the CVT housing 48 so as to mount the electric motor module 400 to the CVT housing 48. Thus, the electric motor module 400 defines the same mounting point pattern as the CVT housing 48, facilitating subsequent installation of the sub-transmission 110.

[0145] AsFigure 34 As shown, the electric motor 410 has a motor shaft 416 that rotates about a motor shaft axis 417. The motor shaft axis 417 extends generally laterally (i.e., generally parallel to the driven pulley axis 67). The motor shaft 416 is operatively connected to the drive assembly 412 such that torque can be transmitted from the electric motor 410 to the drive assembly 412 and vice versa from the drive assembly 412 to the electric motor 410, as will be described in detail below.

[0146] As Figures 34 to 37 shown, the drive assembly 412 includes a gear assembly 430 and a belt drive 440 that are operatively connected to each other. As Figure 35 best shown in, the gear assembly 430 includes a main shaft 432 that rotates about a main shaft axis 419 that is coaxial with the motor shaft axis 417. The main shaft 432 operatively connects the motor shaft 416 to the drive assembly 412. In particular, the main shaft 432 defines a bore 434 that receives the motor shaft 416 therein and is drivingly engaged with the motor shaft 416 via a key and shaft arrangement. The gear assembly 430 also includes a secondary shaft 436 that is operatively connected to the main shaft 432. The secondary shaft 436 rotates about a secondary shaft axis 437 that extends parallel to the main shaft axis 419. As can be observed, two bearings 468, 470 are mounted to the main shaft 432 and two bearings 472, 474 are mounted to the secondary shaft 436. Notably, the main shaft 432 and the secondary shaft 436 are rotatably supported by the housing 414 via the bearings 468, 470, 472, 474. The gear assembly 430 also includes a plurality of gears 460, 462, 464, 466 configured to transmit torque between the main shaft 432 and the secondary shaft 436. The operation of the gear assembly 430 will be described in more detail below.

[0147] The secondary shaft 436 operatively connects the belt drive 440 to the gear assembly 430. The belt drive 440 includes an upper sprocket 442, a lower sprocket 444, and a belt 446 that operatively connects the upper sprocket 442 and the lower sprocket 444. The upper sprocket 442 and the lower sprocket 444 are respectively mounted to the secondary shaft 436 and the drive connecting shaft 448 for rotation with the secondary shaft 436 and the drive connecting shaft 448. The drive connecting shaft 448 is capable of rotating about a connecting shaft axis 449 that extends parallel to the main shaft axis 419 and the secondary shaft axis 437. The drive connecting shaft 448 is laterally disposed between the CVT housing 48 of the CVT 40 and the sub-transmission 110.

[0148] The drive coupling shaft 448 is operatively connected between the driven pulley 44 of the CVT 40 and the gear assembly 430. More specifically, the drive coupling shaft 448 is operatively connected to the driven pulley 44 via a centrifugal clutch 65 and is operatively connected to the gear assembly 430 via a belt drive 440. Thus, as will be described below, torque can be transmitted from the driven pulley 44 to the gear assembly 430 via the drive coupling shaft 448. The drive coupling shaft 448 is also operatively connected to the sub-transmission 110 such that torque can be transmitted from the drive coupling shaft 448 to the output shaft 120 of the sub-transmission 110. In other words, the input shaft 118 of the sub-transmission 110 is operatively connected between the drive coupling shaft 448 and the output shaft 120 of the sub-transmission 110.

[0149] As Figure 35 and Figure 36 shown, the drive coupling shaft 448 defines an externally splined connector 450 at its left end and an internally splined connector 452 at its right end. Notably, the externally splined connector 450 is inserted into a splined output coupler 54 on the right side portion 52 of the CVT housing 48 for driving engagement with the splined output coupler 54. At the opposite end, the internally splined connector 452 receives the input shaft 118 of the sub-transmission 110. In particular, as Figure 33 shown, the internally splined connector 452 is exposed to the right side of the electric motor module 400 via an opening 454 in the right side portion 420 of the housing 414 such that the splined end 121 of the input shaft 118 can be received in the internally splined connector 452.

[0150] As will be understood from the above, both the externally splined connector 450 and the input shaft 118 have matching connection features since both can be received by the output coupler 54. Thus, in a case where the electric motor module 400 is not included as part of the power unit 100, the sub-transmission 110 can be connected to the output coupler 54 regardless of the presence of the electric motor module 400.

[0151] Now will be referred to Figure 36 and Figure 37A more detailed description of the gear assembly 430 is provided. As can be observed, the gears 460, 462, 464, 466 are positioned to be enclosed by the housing 414, i.e., positioned between the middle portion 422 and the left portion 426 of the housing 414. The gears 460, 462, 464, 466 include two main gears 460, 462 that are adjacent to each other and mounted to the main shaft 432, and two sub-gears 464, 466 that are adjacent to each other and mounted to the sub-shaft 436. The main gear 460 and the sub-gear 466 are respectively disposed on the right side of the main gear 462 and the sub-gear 464, and thus the gears can be referred to as the right main gear 460, the left main gear 462, the right sub-gear 466, and the left sub-gear 464. The diameter of the right main gear 460 is larger than the diameter of the right sub-gear 466, while the diameter of the left sub-gear 464 is larger than the diameter of the left main gear 462.

[0152] In this embodiment, the main gears 460, 462 and the sub-gears 464, 466 are meshed together for selective drive engagement therebetween. It is noted that the right main gear 460 is meshed with the right sub-gear 466 for selective drive engagement therebetween (i.e., the teeth 461 of the right main gear 460 are meshed with the teeth 467 of the right sub-gear 466), and the left main gear 462 is meshed with the left sub-gear 464 for selective drive engagement therebetween (i.e., the teeth 463 of the left main gear 462 are meshed with the teeth 465 of the left sub-gear 464). Accordingly, the right main gear 460 rotates in the opposite direction relative to the right sub-gear 466, and the left main gear 462 rotates in the opposite direction relative to the left sub-gear 464.

[0153] It is conceivable that in other embodiments, the main gears 460, 462 may be operatively connected to the sub-gears 464, 466 via intermediate idler gears.

[0154] The two main gears 460, 462 are disposed between two bearings 468, 470 mounted on the main shaft 432. The bearing 468 is rotatably supported by the middle portion 422 of the housing 414, while the bearing 470 is rotatably supported by the left portion 426 of the housing 414. Similarly, the two sub-gears 464, 466 are disposed between two bearings 472, 474 mounted on the sub-shaft 436. The bearing 474 is rotatably supported by the middle portion 422 of the housing 414, while the bearing 472 is rotatably supported by the left portion 426 of the housing 414.

[0155] As will be explained below, the configuration of the gears 460, 462, 464, 466 allows torque to be transmitted between the main shaft 432 and the countershaft 436 in either direction, i.e., from the main shaft 432 to the countershaft 436 and from the countershaft 436 to the main shaft 432. To this end, the right main gear 460 and the left counter gear 464 are freewheel clutch gears that are driven by the main shaft 432 and the countershaft 436 about their respective axes 419, 437 in a single rotational direction. In particular, the right main gear 460 is driven in the rotational direction PR about the main shaft axis 419 (the main shaft axis 419 corresponds to the forward rotational direction of the main shaft 432), and the left counter gear 464 is driven in the rotational direction SR about the countershaft axis 437 (the countershaft axis 437 corresponds to the forward rotational direction of the countershaft 436). Thus, the rotational directions PR, SR can be referred to as the driving rotational directions PR, SR. Since the freewheel clutch gears, the right main gear 460 and the left counter gear 464 can "overrun", the corresponding teeth 461, 465 of the right main gear 460 and the left counter gear 464 rotate at a speed different from that of the corresponding one of the main shaft 432 and the countershaft 436 on which the gears are mounted. This will be explained in further detail below. The right main gear 460 and the left counter gear 464 can also overrun when the main shaft 432 and the countershaft 436 are to rotate in the directions opposite to the rotational directions PR, SR.

[0156] As for the other gears, the left main gear 462 and the right counter gear 466 are spur gears that are fixedly mounted to the main shaft 432 and the countershaft 436 respectively for rotation together with the main shaft 432 and the countershaft 436, such that the left main gear 462 and the right counter gear 466 can be driven by the main shaft 432 and the countershaft 436 about their respective axes 419, 437 in both rotational directions.

[0157] In this embodiment, the freewheel clutch gears 460, 464 have the same configuration to allow their function, however, the freewheel clutch gears 460, 464 are arranged on their respective main shaft 432 and countershaft 436 to be rotationally locked in opposite rotational directions to accommodate the reverse rotation of the main shaft 432 and the countershaft 436. It is noted that with reference to Figure 38 , each of the freewheel clutch gears 460, 464 is a snap-in roller clutch that has an inner ring 480, an outer ring 482 disposed radially outside the inner ring 480, and a clutch adapter 484 disposed between the inner ring 480 and the outer ring 482. The inner ring 480 is fixedly mounted to the corresponding one of the main shaft 432 and the countershaft 436 for rotation therewith. For example, the inner ring 480 is fixed to the corresponding one of the main shaft 432 and the countershaft 436 via a shaft key. The outer ring 482 includes the teeth of the gears 460, 464 (i.e., tooth 461 or tooth 465).

[0158] The clutch adapter 484 is configured to selectively rotationally lock the outer ring 482 with the inner ring 480 such that the inner ring 480 and the outer ring 482 rotate together at the same speed. However, if the inner ring 480 rotates faster than the outer ring 482 in the directions PR or SR, the clutch adapter 484 disengages the outer ring 482 from the inner ring 480 such that the inner ring 480 and the outer ring 482 are in freewheel motion relative to each other and the gear 460 or the gear 464 is said to be over-running. To provide this functionality, in this embodiment, the clutch adapter 484 includes a plurality of ramps 486 connected to and circumferentially distributed around the inner ring 480 and a plurality of rollers 488 connected to the ramps 486. In particular, each roller 488 is operatively connected to a corresponding ramp 486 by a spring 490. In use, when the outer ring 482 of the respective freewheel clutch gear 460, 464 is driven relative to the inner ring 480 in the corresponding driving rotational directions PR, SR, the rollers 488 move outwardly along the ramps 486 and are locked between the ramps 486 and the outer ring 482, thereby coupling the rotation of the outer ring 482 with the inner ring 480. However, when the freewheel clutch gear is over-running, the rollers 488 compress the springs 490 and rollingly contact the outer ring 482 to allow freewheel motion of the outer ring 482 relative to the inner ring 480.

[0159] It is contemplated that in other embodiments, the freewheel clutch gears 460, 464 may be configured in a different manner. For example, the freewheel clutch gears 460, 464 may be of a type other than a snap-in roller clutch (e.g., a sprag clutch).

[0160] Thus, the gear assembly 430 is operable such that in a first scenario, when the rotational speed of the main shaft 432 is greater than the rotational speed of the secondary shaft 436, the main shaft 432 drives the secondary shaft 436 via a driving engagement between the left main gear 462 and the left secondary gear 464. In this scenario, the right main gear 460 is over-running because the driving engagement of the right main gear 460 with the smaller-sized right secondary gear 466 causes the outer ring 482 of the right main gear 460 to rotate slower than the secondary shaft 436 and thus slower than the inner ring 480 of the right main gear 480 (the right main gear 480 rotates at the same speed as the main shaft 432). The inner ring 480 and the outer ring 482 of the right main gear 460 are thus in freewheel motion relative to each other. In this first scenario, the motor 410 can transmit torque to the gear assembly 430 which in turn transmits the torque to the belt drive 440 via the upper sprocket 442 operatively connected to the secondary shaft 436. In turn, the belt drive 440 transmits the torque to the drive connecting shaft 448 to drive the sub-transmission 110 operatively connected to the drive connecting shaft 448.

[0161] In a second scenario, when the rotational speed of the countershaft 436 is greater than the rotational speed of the main shaft 432, the countershaft 436 drives the main shaft 432 via a driving engagement between the right counter gear 466 and the right main gear 460. In this scenario, the left counter gear 464 runs over speed because the driving engagement of the left counter gear 464 with the smaller-sized left main gear 462 causes the outer ring 482 of the left counter gear 464 to rotate slower than the main shaft 432 and thus slower than the inner ring 480 of the left counter gear 464 (the left counter gear 464 rotates at the same speed as the countershaft 436). The inner ring 480 and the outer ring 482 of the left counter gear 464 are thus in freewheel motion relative to each other. In this second scenario, torque can be transmitted to the drive coupling shaft 448 via the CVT 40 and the centrifugal clutch 65, such that the belt drive 440 transmits the torque to the gear assembly 430. The gear assembly 430 then transmits the torque to the motor shaft 416. This can allow the motor 410 to function as a generator to generate and store energy. Alternatively, in some cases, in this second scenario, torque can be transmitted to the gear assembly 430 when the operator of the vehicle releases the throttle but one or more ground engaging members of the vehicle (e.g., the endless track in the case of a snowmobile) still engage the ground and cause the sub-transmission 110 to transmit the torque to the gear assembly 430, thus similarly allowing the motor 410 to function as a generator.

[0162] To control the operation of the electric motor module 400, as Figure 32 and Figure 39 schematically illustrated, a controller 475 is provided, which is in electronic communication with the motor 410 and is thus operable to control the electric motor module 400 in various drive modes.

[0163] As Figure 39 shown, the controller 475 has a processor unit 477 for executing executable code and a non-transitory memory unit 479 for storing the executable code in a non-transitory medium (not shown) included in a memory unit 479. The processor unit 477 includes one or more processors for performing processing operations implementing the functions of the controller 475. The processor unit 477 can be a general-purpose processor or can be a special-purpose processor including one or more pre-programmed hardware or firmware elements (e.g., an application specific integrated circuit (ASIC), an electrically erasable programmable read-only memory (EEPROM), etc.) or other related elements. The non-transitory medium of the memory unit 479 can be a semiconductor memory (e.g., a read-only memory (ROM) and / or a random access memory (RAM)), a magnetic storage medium, an optical storage medium, and / or any other suitable type of memory. Although the controller 475 is represented as one entity in this implementation, it should be understood that the controller 475 can include separate entities for separately controlling the respective components.

[0164] In various drive modes of the electric motor module 400, the controller 475 can be operated to control the electric motor module 400 to be in an engine drive mode. In the engine drive mode, the output shaft 120 of the sub-transmission 110 is driven only by the torque transmitted from the engine 10 to the output shaft 120 of the sub-transmission 110 via the CVT 40, the centrifugal clutch 65, and the drive connecting shaft 448. It should be noted that in the engine drive mode, the torque generated by the electric motor 410 is zero, so that the gear assembly 430 does not contribute to generating the torque transmitted to the sub-transmission 110. Instead, in the engine drive mode, in this embodiment, the drive connecting shaft 448 transmits torque to the belt drive 440, and the belt drive 440 in turn transmits torque to the gear assembly 430. Therefore, the drive connecting shaft 448 transmits torque to the motor shaft 416 via the gear assembly 430, causing the electric motor 410 to operate as a generator to store energy in the battery 495( Figure 39 ).

[0165] The controller 475 can also control the electric motor module 400 to be in an electric motor drive mode. In the electric motor drive mode, the output shaft 120 of the sub-transmission 110 is driven only by the torque transmitted from the electric motor 410 to the output shaft 120 of the sub-transmission 110 via the drive assembly 412 including the gear assembly 430 and the belt drive 440 and the drive connecting shaft 448. It should be noted that in the electric motor drive mode, the driven pulley 44 of the CVT 40 is disengaged from the drive engagement with the output shaft 120 of the sub-transmission 110 and the drive connecting shaft 448. In particular, when the electric motor module 400 is operating in the electric motor drive mode, since the engine 10 is not running or is running at a speed lower than that required for the centrifugal clutch 65 to be in the closed position, the centrifugal clutch 65 is in its open position. Therefore, the outer coupler 69 of the centrifugal clutch 65 does not transmit torque to the output coupler 54, and the output coupler 54 thus does not drive the drive connecting shaft 448.

[0166] Finally, the controller 475 can also control the electric motor module 400 to be in a hybrid drive mode. In the hybrid drive mode, the output shaft 120 of the sub-transmission 110 is driven by the torque transmitted to the output shaft 120 of the sub-transmission 110 through both the motor shaft 416 of the electric motor 410 and the driven pulley 44 of the CVT 40. In other words, in the hybrid drive mode, both the engine 10 and the electric motor 410 transmit torque to the drive connecting shaft 448, and the drive connecting shaft 448 in turn drives the input shaft 118 of the sub-transmission 110, thereby causing the drive of the output shaft 120.

[0167] Accordingly, the electric motor module 400 is provided with an additional torque source that can be utilized to drive the sub-transmission 110. The various drive modes may be useful in different scenarios. For example, the engine drive mode may be useful in scenarios where a large amount of torque is required to drive the vehicle and also helps to generate energy that can charge the battery. Conversely, the electric motor drive mode may be useful in scenarios where a smaller amount of torque is required to drive the vehicle and / or for fuel-saving purposes. As such, the hybrid drive mode can also be used for fuel efficiency purposes since the power unit 100 generates torque from two torque generation sources, thereby reducing the demand on the engine 10. It is contemplated that the controller 475 can control the electric motor module 400 in additional drive modes.

[0168] The operator of the vehicle can select in which drive mode to operate the electric motor module 400. For example, a selection switch (not shown) in communication with the controller 475 is available for the operator to select a desired drive mode on the vehicle's dashboard based on different parameters that the operator can observe (e.g., riding conditions, terrain, fuel availability, etc.). Alternatively, the controller 475 can have different input data transmitted to it by various sensors of the vehicle, based on which the controller 475 can automatically select one of the drive modes. In other words, the controller 475 can select the drive mode based on different parameters of the vehicle (e.g., the vehicle's speed, fuel availability, battery charge level, etc.).

[0169] Power unit for a road vehicle

[0170] Referring to Figure 14 , in another potential configuration, the power unit 100 is configured for a road vehicle and thus the road vehicle sub-transmission 210 is selected from the sub-transmissions 110, 210, 310 as part of the power unit 100. For example, an example of a road vehicle with such a configuration of the power unit 100 can be found in U.S. Patent No. 10,336,387, issued on July 2, 2019, the entire content of which is incorporated herein by reference. The road vehicle sub-transmission 210 is configured to be operatively connected between the CVT 40 and the ground engaging member (i.e., wheel) of the road vehicle for driving the road vehicle.

[0171] Now referring to Figures 15 to 18 the road vehicle sub-transmission 210 will be described. The road vehicle sub-transmission 210 has an interior space that defines the road vehicle sub-transmission 210 and encloses a plurality of gears 250 therein (in Figure 17The sub - transmission housing 212 (schematically shown in [reference]). It should be noted that the sub - transmission housing 212 has a right - hand portion 211 and a left - hand portion 213, and the right - hand portion 211 and the left - hand portion 213 are fastened to each other to enclose the gear 250 and other components therein. The attachment of the portions 211, 213 of the sub - transmission housing 212 seals the road vehicle sub - transmission 210, such that the internal space of the road vehicle sub - transmission 210 is not accessible without disassembling the sub - transmission housing 212.

[0172] The lubrication inlet 248 extends upward from the top portion of the sub - transmission housing 212 for lubricating the drive train of the road vehicle sub - transmission 210.

[0173] As Figure 15 and Figure 18 shown, the road vehicle sub - transmission 210 has an input shaft 218 that extends outward from the sub - transmission housing 212 on the left - hand side 217 of the road vehicle sub - transmission 210. The input shaft 218 is configured to be received by an output coupler 54 such that the CVT 40 and the road vehicle sub - transmission 210 are drivingly engaged. It should be noted that the input shaft 218 and the output coupler 54 are splined and are thus drivingly connected. Thus, in use, the input shaft 218 rotates about the driven pulley axis 67.

[0174] The gear 250 operatively connects the input shaft 218 to the output shaft 220 of the road vehicle sub - transmission 210 (schematically shown in [reference]). The output shaft 220 is capable of rotating about an output shaft axis 225 that extends in a direction generally parallel to the driven pulley axis 67 such that when the power unit 100 is mounted on a road vehicle, the output shaft axis 225 extends generally laterally. A drive sprocket 270 is mounted and fastened to the output shaft 220 for rotation therewith. The drive sprocket 270 is configured to be operatively connected to the wheel of the road vehicle. It should be noted that in use, a drive chain is attached to the drive sprocket 270 and the drive chain is operatively connected to the drive wheel of the road vehicle. For this purpose, as Figure 18 shown in Figure 16 and Figure 18 the drive sprocket 270 is positioned outside the sub - transmission housing 212. More specifically, the drive sprocket 270 is positioned to the right of the right - hand portion 211 of the sub - transmission housing 212.

[0175] As Figure 15 shown in Figure 17 and Figure 18 in order to connect to the CVT 40, the road vehicle sub - transmission 210 has a plurality of mounting connectors 245 1 -245 4 wherein the plurality of mounting connectors 245 1 -2454 configured to engage with the sub - transmission mount 64 of the CVT housing 48 1 -64 4 Engagement. Notably, in this embodiment, each of the mount connectors 245 1 -245 4 is a fastener that extends through two portions 211, 213 of the sub - transmission housing 212 to threadedly engage a corresponding one of the sub - transmission mounts 64 1 -64 4 therein.

[0176] Specifically referring to Figure 16 , the sub - transmission housing 212 of the road vehicle sub - transmission 210 defines two vehicle mounts 227. In addition to the vehicle mount 60 of the engine 10, the power unit 100 can also be mounted to the road vehicle through the two vehicle mounts 227. In this embodiment, the vehicle mounts 227 include an upper vehicle mount 227 and a lower vehicle mount 227. Each vehicle mount 227 is configured to receive a fastener therein for attachment to the frame of the road vehicle.

[0177] As can be observed, compared with the snow vehicle sub - transmission 110, the road vehicle sub - transmission 210 does not have a shifter for operating the sub - transmission 210 in different gears. Thus, in this embodiment, the changes in speed and torque can be provided only by the CVT 40.

[0178] The power unit 100 including the road vehicle sub - transmission 210 is shown assembled in Figures 19 to 22 . As can be observed, the power unit 100 is configured such that the crankcase 12 of the engine 10 and a portion of the road vehicle sub - transmission 210 are disposed on the right side of the CVT 40. As Figure 22 shown, the road vehicle sub - transmission 210 is laterally disposed between the lateral ends of the engine 10. Further, referring to Figure 19 , the output shaft axis 225 of the output shaft 220 is coaxial with the driven pulley axis 67 (i.e., the driven pulley axis 67 and the drive sprocket 270 rotate about the same axis).

[0179] Additionally, as can be observed, all of the mounting points defined by the sub - transmission mounts 64 of the CVT housing 48 1 -64 4 are used to mount the road vehicle sub - transmission 210 to the CVT housing 48. That is, each of the sub - transmission mounts 64 of the CVT housing 48 1 -64 4 receives a corresponding one of the mount connectors 245 1 -245 4 therein.

[0180] Similar to the above description of the snow vehicle transmission 110, the road vehicle transmission 210 is a modular unit of the power unit 100, which is attached to the CVT 40 but is otherwise spatially independent of the CVT 40. Notably, the internal space of the road vehicle transmission 210, as defined by the sub-transmission housing 212, is sealed relative to the CVT housing 48. Thus, the air flow within the CVT housing 48 is independent of the road vehicle transmission 210. In other words, the air flow entering the CVT housing 48 (via the air inlet 45) does not enter the internal space of the road vehicle transmission 210.

[0181] It should be understood that this particular configuration of the power unit 100 is not limited to use with road vehicles, but can alternatively be used for other vehicles driven by the drive sprocket 270.

[0182] In addition, as Figure 40 shown, as described above for the snow vehicle transmission 110, the road vehicle transmission 210 can alternatively be operatively connected to the output coupler 54 via the electric motor module 400 rather than directly connected to the output coupler 54. The power unit 100 including the road vehicle transmission 210 can thus benefit from the different drive modes provided by the electric motor module 400 as described above.

[0183] Power unit for an all-terrain vehicle (ATV)

[0184] Referring Figure 23 , in another configuration, the power unit 100 is configured for an ATV and thus the ATV sub-transmission 310 is selected from the sub-transmissions 110, 210, 310 as part of the power unit 100. For example, an example of an ATV for which the power unit 100 can be provided in this configuration can be found in U.S. Patent No. 9,283,823, issued on March 15, 2016, the entire content of which is incorporated herein by reference. The ATV sub-transmission 310 is configured to be operatively connected between the CVT 40 and two independent ground engaging members of the ATV (i.e., two separate driven wheels) for driving the ATV.

[0185] Now, the ATV sub-transmission 310 will be described with reference to Figures 24 to 26 The ATV sub-transmission 310 has an internal space that defines the ATV sub-transmission 310 and encloses a plurality of gears 350 therein (in Figure 25The sub - transmission housing 312 (schematically shown in). It is noted that the sub - transmission housing 312 has a right - hand portion 311 and a left - hand portion 313, and the right - hand portion 311 and the left - hand portion 313 are fastened to each other to enclose the gear 350 and other components therein. The attachment of the portions 311, 313 of the sub - transmission housing 312 seals the ATV sub - transmission 310 such that the internal space of the ATV sub - transmission 310 is not accessible without disassembling the sub - transmission housing 312.

[0186] Referring to Figure 26 , the ATV sub - transmission 310 has an input shaft 318 that extends outwardly from the sub - transmission housing 312 at the left - hand side 317 of the ATV sub - transmission 310. The input shaft 318 is configured to be received by an output coupler 54 such that the CVT 40 and the ATV sub - transmission 310 are drivingly engaged. It is noted that the input shaft 318 and the output coupler 54 are splined and are thus drivingly connected. Thus, in use, the input shaft 318 rotates about the driven pulley axis 67.

[0187] The gear 350 operatively connects the input shaft 318 to two output shafts 321, 323 of the ATV sub - transmission 310, which two output shafts 321, 323 may be referred to as a “rear output shaft” 321 and a “front output shaft” 323. The rear output shaft 321 and the front output shaft 323 are capable of rotating about respective axes 325, 329, and the axes 325, 329 each extend in a direction generally transverse to the driven pulley axis 67 such that when the power unit 100 is mounted on the ATV, the output shaft axes 325, 329 extend generally longitudinally. As can be observed in Figure 26 , the output shaft axis 325 of the rear output shaft 321 is vertically higher than the output shaft axis 329 of the front output shaft 323. Further, as Figure 25 shown, the rear output shaft 321 and the front output shaft 323 are laterally spaced from each other such that in use the rear output shaft 321 is closer to the CVT 40 than the front output shaft 323. Thus, the output shaft axes 325, 329 are laterally offset from each other. The rear output shaft 321 and the front output shaft 323 are configured to be operatively connected to the rear and front wheels of the ATV, respectively. It is noted that in use, each of the rear output shaft 321 and the front output shaft 323 is attached to a respective drive shaft and the respective drive shafts are operatively connected to the rear and front wheels of the ATV via a rear differential and a front differential.

[0188] As Figure 26 shown, for connection to the CVT 40, the ATV sub - transmission 310 has a plurality of mounting connectors 345 1 - 345 4 , the plurality of mounting connectors 345 1 - 345 4configured to engage with the sub - transmission mount 64 of the CVT housing 48 1 -64 4 Engage. Notably, in this embodiment, the mount connector 345 1 -345 4 Each of which is a fastener that is inserted into a corresponding opening in the sub - transmission housing 312 to threadedly engage a corresponding one of the sub - transmission mounts 64 1 -64 4 One of the corresponding ones.

[0189] Specifically referring to Figure 24 、 Figure 27 、 Figure 29 And Figure 30 , the sub - transmission housing 312 of the ATV sub - transmission 310 defines a vehicle mount 327. In addition to the vehicle mount 60 of the engine 10, the power unit 100 can also be mounted to the ATV through the vehicle mount 327. In this embodiment, the vehicle mount 327 includes an opening for inserting a corresponding protruding mounting member of the frame of the ATV therein.

[0190] The ATV sub - transmission 310 also has a shifter 340 including a shifter lever for selectively engaging the input shaft 318 with one of the gears 350. More specifically, in use, the shifter 340 can be operated by the user of the ATV to engage the gears of the ATV sub - transmission 310 in order to change the drive operation of the output shafts 321, 323. Notably, the shifter 340 allows the user to operate the ATV sub - transmission 310 in one of a plurality of "gear positions", which in this embodiment include high gear, low gear, neutral, and reverse. Notably, specific gears among the gears 350 are associated with high gear, low gear, and reverse, such that when engaged via the shifter 340, the ATV is driven in high gear, low gear, and reverse respectively.

[0191] It is conceivable that in other embodiments, the ATV sub - transmission 310 can be operated in a different number of gear positions.

[0192] The power unit 100 including the ATV sub - transmission 310 is shown as assembled in Figures 27 to 31 . As can be observed, the power unit 100 is configured such that the crankcase 12 of the engine 10 and a portion of the ATV sub - transmission 310 are disposed on the right side of the CVT 40. Notably, as Figure 31 Shown, a portion of the ATV sub - transmission 310 extends laterally away from the CVT 40 (i.e., towards the right side) past the engine 10. For example, in this embodiment, a portion of the sub - transmission housing 312 extends laterally away from the CVT 40 past the engine 10.

[0193] In addition, as can be observed, all of the mounting points defined by the sub-transmission mountings 64 of the CVT housing 48 1 -64 4 are used to mount the ATV sub-transmission 310 to the CVT housing 48. That is, each of the sub-transmission mountings 64 of the CVT housing 48 1 -64 4 receives a corresponding one of the mounting connectors 345 1 -345 4 therein.

[0194] Similar to the description above regarding the sub-transmissions 110, 210, the ATV sub-transmission 310 is a modular unit of the power pack 100 that is attached to the CVT 40 but is otherwise spatially independent of the CVT 40. Notably, the internal space of the ATV sub-transmission 310 defined by the sub-transmission housing 312 is sealed relative to the CVT housing 48. Thus, the air flow within the CVT housing 48 is independent of the ATV sub-transmission 310. In other words, the air flow entering the CVT housing 48 (via the air inlet 45) does not enter the internal space of the ATV sub-transmission 310.

[0195] It should be understood that this particular configuration of the power pack 100 is not limited to use with an ATV, but can alternatively be used for other vehicles driven by two longitudinally extending output shafts 321, 323.

[0196] In addition, as Figure 41 shown, as described above regarding the snowmobile sub-transmission 110, the ATV sub-transmission 310 can alternatively be operatively connected to the output coupler 54 via the electric motor module 400 rather than directly connected to the output coupler 54. The power pack 100 including the ATV sub-transmission 310 can thus benefit from the different drive modes provided by the electric motor module 400 as described above.

[0197] In different possible configurations of the power pack 100, regardless of which one of the sub-transmissions 110, 210, 310 is attached to the CVT housing 48 (or the electric motor module 400), the configurations of the CVT 40 and the engine 10 remain the same. For example, regardless of the sub-transmissions 110, 210, 310 used, the air inlets 45 and 47 of the CVT housing 48 remain in the same positions. In other words, the same CVT 40 and the same engine 10 can be used for any selected one of the sub-transmissions 110, 210, 310.

[0198] Accordingly, the method for assembling the power pack 100 is simplified, i.e., simplified in part by its use of a common CVT and a common engine for any of the sub-transmissions 110, 210, 310. In particular, to assemble the power pack 100, the engine 10 and the CVT 40 are provided and operatively connected to each other. Then, it is determined which of a snowmobile, a road vehicle, and an ATV is to be provided with the power pack 100. Based on this determination, one of the sub-transmissions 110, 210, 310 is selected for installation to the CVT 40 as described above. Since each of the sub-transmissions 110, 210, 310 has mounting connectors 145 1 -145 4 , 245 1 -245 4 , 345 1 -345 4 of the same configuration, and the CVT housing 48 has mounting points of a matching configuration, so that the selected one of the sub-transmissions 110, 210, 310 can then be easily installed to the CVT housing 48.

[0199] Since the engine 10 and the CVT 40 are similar in all configurations, the power pack 100 can be provided relatively easily in any of its potential configurations. It is noted that the sub-transmissions 110, 210, 310 used in the power pack 100 are adapted to the drive requirements of a corresponding one of a snowmobile, a road vehicle, and an ATV. This can facilitate the manufacture of all these different vehicles, as fewer parts are required to produce the different vehicles, and thus the associated costs are reduced.

[0200] Modifications and improvements to the above-described embodiments of the present technology may be apparent to those skilled in the art. The foregoing description is intended to be exemplary and not restrictive. Accordingly, the scope of the present technology is intended to be limited only by the scope of the appended claims.

Claims

1. A power unit for a vehicle selected from a group of different vehicles, the power unit comprising: an internal combustion engine, the internal combustion engine comprising: a crankcase; a crankshaft disposed within the crankcase; and a cylinder block connected to the crankcase; a continuously variable transmission operatively connected to the engine, the continuously variable transmission comprising: a drive pulley operatively connected to the crankshaft of the engine, the drive pulley being rotatable about a drive pulley axis; a driven pulley rotatable about a driven pulley axis; a belt connecting the drive pulley to the driven pulley; and a housing at least partially enclosing the drive pulley, the driven pulley, and the belt; and a sub - transmission selected from a group of different sub - transmissions according to the selected vehicle from the group of different vehicles, the selected sub - transmission being mounted to the housing of the continuously variable transmission, the housing of the continuously variable transmission being configured to mount any of the group of different sub - transmissions, the group of different sub - transmissions comprising: a first sub - transmission, the first sub - transmission comprising: an input shaft configured to be operatively connected to the driven pulley of the continuously variable transmission; a plurality of gears; and an output shaft operatively connected to the input shaft via the plurality of gears, the output shaft being rotatable about a laterally extending output shaft axis, each of a first end portion and a second end portion of the output shaft being configured to be operatively connected to a respective ground - engaging member of the selected vehicle; a second sub - transmission, the second sub - transmission comprising: an input shaft configured to be operatively connected to the driven pulley of the continuously variable transmission; a plurality of gears; and an output sprocket operatively connected to the input shaft via the plurality of gears, the output sprocket being configured to be operatively connected to a ground - engaging member of the selected vehicle for driving the selected vehicle; and a third sub - transmission, the third sub - transmission comprising: an input shaft configured to be operatively connected to the driven pulley of the continuously variable transmission; a plurality of gears; and a first output member and a second output member operatively connected to each other and driven by the input shaft via the plurality of gears, the first output member and the second output member being disposed on opposite sides of the third sub - transmission, the first output member and the second output member being rotatable about respective axes extending generally longitudinally.

2. The power unit according to claim 1, wherein: the housing of the continuously variable transmission defines a plurality of mounting points for mounting the selected sub - transmission to the housing; and at least some of the mounting points defined by the housing are for mounting any one of the different sub - transmissions.

3. The power unit according to claim 1, wherein, All mounting points defined by the housing of the continuously variable transmission are used to mount any one of the different sub-transmissions.

4. The power unit according to claim 1, wherein, when the power unit is mounted on a selected vehicle, the driving pulley axis is vertically higher than the driven pulley axis.

5. The power unit according to claim 1, wherein, when the power unit is mounted on a selected vehicle, the driven pulley axis extends substantially laterally.

6. The power unit according to claim 1, wherein: at least a portion of the crankcase of the engine and at least a portion of a selected sub-transmission are disposed on the same side of the continuously variable transmission.

7. The power unit according to claim 6, wherein, at least a portion of the selected sub-transmission extends laterally away from the continuously variable transmission past the engine.

8. The power unit according to claim 1, wherein: the first output member and the second output member of the third sub-transmission are a first output shaft and a second output shaft; and when the selected sub-transmission is the third sub-transmission, the respective axes about which the first output shaft and the second output shaft rotate extend in a direction substantially transverse to the driven pulley axis.

9. The power unit according to claim 8, wherein, the respective axes about which the first output shaft and the second output shaft rotate are vertically lower than the driven pulley axis.

10. The power unit according to claim 1, wherein: when the selected sub-transmission is the first sub-transmission, the output shaft axis of the first sub-transmission extends in a direction substantially parallel to the driven pulley axis.

11. The power unit according to claim 10, wherein, the output shaft axis is vertically lower than the driven pulley axis.

12. The power unit according to any one of claims 1 to 7, wherein, at least one sub-transmission of the group of different sub-transmissions includes: a sub-transmission housing, a plurality of gears of the at least one sub-transmission, the plurality of gears of the at least one sub-transmission being enclosed within the sub-transmission housing; and a shifter for selectively engaging the input shaft of the at least one sub-transmission with one of the plurality of gears of the at least one sub-transmission.

13. The power unit according to any one of claims 1 to 7, wherein: the first sub-transmission further includes a sub-transmission housing; the plurality of gears of the first sub-transmission are enclosed within the sub-transmission housing; the input shaft of the first sub-transmission is drivingly engaged with the plurality of gears of the first sub-transmission; and the output shaft of the first sub-transmission extends laterally outwardly from a first lateral side and a second lateral side of the sub-transmission housing.

14. The power unit according to claim 1, wherein: the second sub-transmission further includes a sub-transmission housing that encloses the plurality of gears within the sub-transmission housing; and the output sprocket is positioned outside the sub-transmission housing.

15. The power unit according to claim 1, wherein: the engine defines a plurality of engine mounts for mounting the engine to a frame of a selected vehicle; and for at least some of the different vehicles in the group, only some of the engine mounts are used to mount the engine to the frame.

16. The power unit according to claim 15, wherein, the selected sub-transmission defines additional vehicle mounts for mounting the power unit to the frame of the selected vehicle.

17. The power unit according to claim 1, wherein: at least one sub-transmission in the group of different sub-transmissions includes a sub-transmission housing, the sub-transmission housing defines an internal space of the at least one sub-transmission; and the sub-transmission housing is sealed such that the internal space of the at least one sub-transmission is inaccessible without disassembling the sub-transmission housing.

18. The power unit according to claim 1, wherein: at least one sub-transmission in the group of different sub-transmissions includes a sub-transmission housing; the sub-transmission housing defines an internal space of the at least one sub-transmission; and when the selected sub-transmission is one of the at least one sub-transmissions, the sub-transmission housing of the at least one sub-transmission is sealed relative to the housing of the continuously variable transmission.

19. The power unit according to claim 1, wherein: at least one sub-transmission in the group of different sub-transmissions includes a reverse gear; and when the selected sub-transmission is the at least one sub-transmission including the reverse gear, the power unit is operable to drive the vehicle in reverse via engagement of the reverse gear.

20. The power unit according to claim 1, wherein: the housing of the continuously variable transmission defines an air inlet and an air outlet; and regardless of the selected sub-transmission, the air inlet and the air outlet are always in the same position.

21. The power unit according to claim 1, wherein, the engine is a single-cylinder engine.

22. A method for assembling a power unit for a vehicle selected from a group of different vehicles, the method comprising: providing an engine and a continuously variable transmission operatively connected to the engine; determining the selected vehicle for which the power unit is to be provided; determining the drive requirements of the selected vehicle, the drive requirements including one of the following: an input shaft is rotatable about an output shaft axis extending laterally, each of a first end portion and a second end portion of the output shaft being configured to be operatively connected to a respective ground engaging member of the selected vehicle; an output sprocket is configured to be operatively connected to a ground engaging member of the selected vehicle; and a first output member and a second output member are operatively connected to each other, the first output member and the second output member being rotatable about respective axes extending generally longitudinally; Select a sub-transmission from a group of different sub-transmissions based on the drive requirements of the selected vehicle for which the power unit is to be provided; and Mount the selected sub-transmission to the housing of the continuously variable transmission, the housing of the continuously variable transmission being configured to mount any of the group of different sub-transmissions.

23. The method according to claim 22, wherein, For any one of the different sub-transmissions being the selected sub-transmission, mounting the selected sub-transmission includes: Fastening the selected sub-transmission to all of a plurality of mounting points defined by the housing of the continuously variable transmission for mounting the selected sub-transmission.

24. The method according to claim 22, wherein, For at least one of the different sub-transmissions being the selected sub-transmission, mounting the selected sub-transmission includes: Positioning the selected sub-transmission such that the axis of the output shaft of the selected sub-transmission extends in a direction generally transverse to the axis of the driven pulley of the continuously variable transmission.

25. The method according to claim 22, wherein, For at least one of the different sub-transmissions being the selected sub-transmission, mounting the selected sub-transmission includes: Positioning the selected sub-transmission such that the axis of the output shaft of the selected sub-transmission extends in a direction generally parallel to the axis of the driven pulley of the continuously variable transmission.

Images