WO2019049109A1

WO2019049109A1 - Battery arrangement for electric snow vehicles

Info

Publication number: WO2019049109A1
Application number: PCT/IB2018/056940
Authority: WO
Inventors: Paul ACHARD; Samuel BRUNEAU
Original assignee: Taïga Motors Inc.
Priority date: 2017-09-11
Filing date: 2018-09-11
Publication date: 2019-03-14

Abstract

An electric snow vehicle comprising: a chassis; an endless track operatively connected to the chassis to move the electric snow vehicle; at least one ground engagement member disposed adjacent to the front chassis end and operatively secured to the chassis; an electric motor; a drive shaft operatively connected to the electric motor and to the endless track for activating the endless track, the drive shaft being rotatably secured to the chassis adjacent to the front track end of the endless track; a battery securable to the chassis for powering the electric motor and thereby triggering an activation of the endless track to move the electric snow mobile, the battery being positionable so that a center of mass of the battery be located at a given position along the longitudinal axis of the chassis, the given position being in forward position relative to drive shaft.

Description

BATTERY ARRANGEMENT FOR ELECTRIC SNOW VEHICLES

TECHNICAL FIELD

The present invention relates to the field of snow vehicles, and more particularly to a battery arrangement for snow vehicles. BACKGROUND

Conventional snow vehicles are typically comprised of a partially unsprung and endless track drive assembly and one or more forward ground engaging members. A powertrain assembly is usually located centrally along the length of the vehicle. One or more operators straddle the chassis above the track assembly. Like most off-road vehicles, snow vehicles are typically powered by an internal combustion engine. Therefore, such snow vehicles typically consume petroleum based fuels and emit exhaust gases such as carbon dioxide and nitrous oxides. These gases are known to contribute to the greenhouse effect.

Furthermore, internal combustion engines typically generate elevated noise levels at certain operating speeds. These noise levels are known to contribute to local noise pollution.

In order to reduce or eliminate fuel consumption and greenhouse gas emissions and to reduce noise emissions, some usual internal combustion engines have been replaced by electric motors. An increased number of automobiles and motorcycles are now powered by one or more electric motors. Due to their quieter, cleaner and more efficient drive systems, electric vehicles offer a promising alternative to combustion vehicles. However, to be successful, an electric vehicle needs to meet consumers' expectations relative to performance, range, reliability and cost. Particularly, maneuverability of an electric vehicle such as an electric snow vehicle may be of importance and maneuverability should be taken in account while designing the powertrain of any electric vehicle. Usual electric vehicle powertrains comprise a motor, a motor drive, a battery and auxiliary systems. The battery of an electric vehicle is usually the heaviest single element of the powertrain and its position may affect at least the maneuverability of an electric snow vehicle. In usual electric snow vehicle such as usual electric snowmobiles, the battery is disposed above the endless track assembly. While it facilitates the integration of the battery into conventional combustion snow vehicle frames, such a position of the battery promotes a high center of gravity which results in an unstable cornering behavior.

Therefore, there is a need for an improved electric snow vehicle.

SUMMARY

According to a broad aspect, there is provided an electric snow vehicle comprising: a chassis extending longitudinally between a front chassis end and a rear chassis end along a longitudinal axis; an endless track operatively connected to the chassis to move the electric snow vehicle, the endless track extending between a front track end and a rear track end; at least one ground engagement member disposed adjacent to the front chassis end and operatively secured to the chassis; an electric motor; a drive shaft operatively connected to the electric motor and to the endless track for activating the endless track, the drive shaft being rotatably secured to the chassis adjacent to the front track end of the endless track between the front and rear track ends; a battery securable to the chassis and connectable to the electric motor for powering the electric motor and thereby triggering an activation of the endless track to move the electric snow mobile, the battery being positionable so that a center of mass of the battery be located at a given position along the longitudinal axis of the chassis, the given position being in forward position relative to drive shaft.

In one embodiment, the given position for the battery is in forward position relative to the front track end of the endless track. In one embodiment, the battery is further positionable so that the center of mass of the battery be located between about 500 mm below a topmost point of the endless track and about 400 mm above the topmost point of the endless track along a vertical axis, the vertical axis being orthogonal to the longitudinal axis. In one embodiment, the center of mass of the battery is located less than 500 mm ahead of the front track end of the endless track, along the longitudinal axis.

In one embodiment, the electric snow vehicle further comprises a battery cradle for receiving the battery, the battery cradle being positioned and designed so that, when the battery is received therein, the center of mass of the battery is located in the forward position relative to the front track end.

In one embodiment, the whole battery is positionable forward relative to the drive shaft.

In one embodiment, the whole battery is positionable forward relative to the front track end of the endless track. In one embodiment, a portion of the battery may overlap the endless track. In one embodiment, the ground engaging member comprises at least one ski. In one embodiment, the battery has an electric charge of at least 5 kilowatt-hours. In one embodiment, the battery comprises a battery pack.

In one embodiment, the electric snow vehicle further comprises a power interface for controlling a distribution of an electrical current delivered by the battery pack.

According to another broad aspect, there is provided an electric snow vehicle comprising: a chassis extending longitudinally between a front chassis end and a rear chassis end along a longitudinal axis; an endless track operatively connected to the chassis to move the electric snow vehicle, the endless track extending between a front track end and a rear track end; at least one ground engagement member disposed adjacent to the front chassis end and operatively secured to the chassis; an electric motor; a drive shaft operatively connected to the electric motor and to the endless track for activating the endless track, the drive shaft being rotatably secured to the chassis adjacent to the front track end of the endless track between the front and rear track ends; a battery secured to the chassis and connected to the electric motor for powering the electric motor and thereby triggering an activation of the endless track to move the electric snow mobile, the battery being positioned so that a center of mass of the battery be located at a given position along the longitudinal axis of the chassis, the given position being in forward position relative to drive shaft.

In one embodiment, the given position for the battery is in forward position relative to the front track end of the endless track.

In one embodiment, the battery is further positioned so that the center of mass of the battery be located between about 500 mm below a topmost point of the endless track and about 400 mm above the topmost point of the endless track along a vertical axis, the vertical axis being orthogonal to the longitudinal axis. In one embodiment, the center of mass of the battery is located less than 500 mm ahead of the front track end of the endless track, along the longitudinal axis.

In one embodiment, the whole battery is positionable forward relative to the front track end of the endless track.

In one embodiment, a portion of the battery may overlap the endless track. In one embodiment, the ground engaging member comprises at least one ski.

In one embodiment, the battery has an electric charge of at least 5 kilowatt-hours. In one embodiment, the battery comprises a battery pack.

In one embodiment, the electric snow vehicle further comprises a power interface for controlling a distribution of an electrical current delivered by the battery pack. Terms related to spatial orientation such as forwardly, rearwardly, front, rear, upper, lower, left, and right, are as they would normally be understood by a driver of the vehicle sitting in a normal driving position.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

Figure 1 is a side-view schematic illustration of the exterior of a snowmobile chassis constructed according to the teachings of the present invention, in its preferred embodiment, defining a forwardmost point on an endless track assembly, and depicting a dashed representation of a rider positioning;

Figure 2 is an enlarged and cropped perspective illustration, from the front right side, illustrating the exterior of a snowmobile chassis constructed according to the teachings of the present invention;

Figure 3 a is a cropped side-view schematic illustration of the exterior of a snowmobile chassis constructed according to the teachings of the present invention, in a second embodiment;

Figure 3b is a cropped side-view schematic illustration of the exterior of a snowmobile chassis constructed according to the teachings of the present invention, in a third embodiment; Figure 3 c is a cropped side-view schematic illustration of the exterior of a snowmobile chassis constructed according to the teachings of the present invention, in a fourth embodiment;

Figure 4a is a perspective illustration, from the front-right side, of the preferred embodiment of an accumulator, wherein the walls of the battery enclosure are shown with transparency; Figure 4b is a perspective illustration, from the front-right side, of a second embodiment of a battery, wherein the walls of the battery enclosure are shown with transparency;

Figure 4c is a perspective illustration, from the front-right side, of a third embodiment of a battery, wherein the walls of the battery enclosure are shown with transparency; Figure 4d is a perspective illustration, from the front-right side, of a fourth embodiment of a battery, wherein the walls of the battery enclosure are shown with transparency;

Figure 5 is a perspective illustration, from the front-right side, of the preferred embodiment of a battery, wherein the battery enclosure is hidden, and wherein the battery module interconnects are shown in an exploded view; Figure 6 is a perspective illustration, from the front- right side, of a second embodiment of a battery, wherein the battery enclosure is hidden, and wherein the battery module interconnects and the battery internal cabling are shown in an exploded view;

Figure 7 is a perspective illustration, from the front-right side, of a third embodiment of a battery, wherein the battery enclosure is hidden, and wherein the battery module interconnects and the battery internal cabling are shown in an exploded view;

Figure 8 is a perspective illustration, from the front-right side, of a fourth embodiment of a battery, wherein the battery enclosure is hidden, and wherein a portion of the battery module interconnects and the battery internal cabling are shown in an exploded view;

Figure 9 is a perspective illustration, from the front-right side, of the preferred embodiment of a battery module, wherein the module cover, the fasteners and a portion of the battery cells are shown in an exploded view.

Figure 10a is a perspective illustration, from the front-right side, of a second embodiment of a battery module, wherein the module cells and the cell are shown in an exploded view.

Figure 10b is a perspective illustration, from the front-right side, of a second embodiment of a battery module; Figure 11a is a cropped cross-sectional view of the preferred embodiment of a permanent cell connection;

Figure l ib is a cropped cross-sectional view of a second embodiment of a permanent cell connection; Figure 11c is a cropped cross-sectional view of a third embodiment of a permanent cell connection;

Figure l id is a cropped cross-sectional view of a fourth embodiment of a permanent cell connection;

Figure l ie is a cropped cross-sectional view of a fifth embodiment of a permanent cell connection;

Figure 12a is a cropped perspective view of the preferred embodiment of a serviceable cell connection;

Figure 12b is a cropped perspective view of a second embodiment of a serviceable cell connection; Figure 12c is a cropped perspective view of a third embodiment of a serviceable cell connection; and

Figure 13 is a perspective illustration representing the rear suspension assembly and track of the snow vehicle, wherein the track is represented in a transparent state.

It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION

There is described an electric snow vehicle such as an electric snowmobile comprising at least a chassis or frame, an endless track, an electric motor, a battery or battery assembly, and a ground engaging member. The chassis extends longitudinally between a front end and a rear end. The battery is used for powering the electric motor which in turn activates the endless track. The endless track is operatively connected to the chassis so as to engage the ground in order to propel the snow vehicle. The ground engaging member is secured at the front end of the chassis to control the movement direction of the snow vehicle. The electric snowmobile is further provided with a drive shaft rotatably secured to the chassis and operatively connected to the electric motor and the endless track so as to transfer power from the electric motor to the endless track and activate the endless track upon rotation of the drive shaft. The drive shaft extends at least partially within the inside space defined the endless trach adjacent to the front end of the endless track.

The battery is secured or securable directly or indirectly to the chassis at a given position along the longitudinal axis of the chassis so that its center of mass be in a forward or upfront position relative to the drive shaft, i.e. the center of mass of the battery is located between the drive shaft and the ground engaging member.

In one embodiment, the given position of the battery along the longitudinal axis of the chassis chosen so as to be in a forward or upfront position relative to the front end of the endless track, i.e. the center of mass of the battery is located between the front end of the endless track and the ground engaging member.

In one embodiment, the position of the battery is further chosen so that the center of mass of the battery is located within at a predefined range of positions along the vertical axis, i.e. between about 500 mm below the topmost point of the endless track and about 400 mm above the topmost point of the endless track.

The person skilled in the art will understand that the snow vehicle may further comprise elements such as a bodywork including a hood, a steering device for controlling the ground engaging member, a seat, a vehicle control module for controlling operation of the snow vehicle, a motor control module for controlling operation of the electric motor, thermal management systems, mounting systems, lights, a windshield, headlights, suspensions, a snow flap, passenger grips, a control panel, a handlebar, a throttle, a brake lever, switches, etc. It should be understood that the snow vehicle may comprise more than one endless track and/or more than one drive shaft. In an embodiment in which the snow vehicle comprises at least two drive shafts, the center of mass of the battery is located at a position forward from the forwardmost drive shaft, i.e. at a forward position from the drive shaft that is the closest to the front end of the endless track.

In an embodiment in which the snow vehicle comprises at least two endless tracks, the center of mass of the battery may be located at a position forward from the front end position of each endless track as long as the center of mass of the battery is located at a position forward from the forwardmost drive shaft. In one embodiment, the center of mass is further positioned as so to be between about 500 mm below the topmost point of the endless track and about 400 mm above the topmost point of the endless track along the vertical axis.

In one embodiment, the chassis may comprise a battery cradle for receiving the battery therein. The battery cradle is positioned and designed so that, when the battery is received therein, the center of mass of the battery is located at a position along the longitudinal axis of the snow vehicle that is forward relative to the drive shaft.

In one embodiment, the battery cradle is positioned and designed so that, when the battery is received therein, the center of mass of the battery is located at a position forward from the front end of the endless track. In one embodiment, the battery cradle is positioned and designed so that, when the battery is received therein, the center of mass of the battery be located between about 500 mm below the topmost point of the endless track and about 400 mm above the topmost point of the endless track along the vertical axis.

In one embodiment, the whole battery is positioned forward relative to the drive shaft. In another embodiment, a portion of the battery may overlap the drive shaft as long as the center of mass of the battery is located forward to the drive shaft In one embodiment, the whole battery is positioned forward relative to the front end of the endless track. In another embodiment, a portion of the battery may overlap the endless track as long as the center of mass of the battery is located forward to the front end of the endless track and optionally between about 500 mm below the topmost point of the endless track and about 400 mm above the topmost point of the endless track along the vertical axis.

In one embodiment, the battery is a battery pack and comprises a plurality of battery modules or units connected together as to be serviceable and each battery module or unit comprises a plurality of battery cells connected together.

When the battery is a battery pack, the center of mass of the battery pack is defined as the mass-based centroid of all components contained within the battery pack.

As mentioned above, usual electric snow vehicles use frames or chassis of conventional combustion snow vehicles which are retrofitted to match the particular needs of the electric propulsion system. Particularly, the space occupied by the tank on a conventional combustion snow vehicle is used for receiving the battery in a retrofitted electric snow vehicle. While it facilitates integration of the battery into a conventional combustion snow vehicle frames, such a position for the battery however promotes a center of gravity of which the position may result in an unstable cornering behavior.

In contrast, by placing the battery pack of an electric snow vehicle forward of the track assembly, it is also possible to vertically lower its position in such a way to vertically lower the center of gravity of the vehicle significantly, thus resulting in a more stable cornering behavior.

Figure 1 illustrates one embodiment of an electric snow vehicle 1. The snow vehicle 1 comprises a chassis formed of a tunnel 3 and a forward chassis structure 4 which are secured together or integral together. The forward chassis structure 4 comprises a recess for receiving a battery pack 6 therein, and supports a front suspension arrangement. The tunnel 3 supports a rear suspension arrangement 14, an endless track 5, an electric motor 11, a motor controller 12 and a seat 18 which is to be straddled by a rider 2. Referring to Figure 2, there is shown a front suspension structure connecting two ground engaging members 27 (i.e. two skis 27) to the forward chassis structure 4. In this embodiment, the skis 27 are pivotally connected to a pair of upright members 21 steerable about their longitudinal axis. The steerable upright members 21 are each pivotally connected to a respective suspension arm 17 and each pivotally connected to a respective steering link member 22 extending inwardly. The steering link members 22 are pivotally connected to a steering shaft 19. The steering shaft 19 is pivotally supported by the forward chassis section 4. The suspension arms 17 each extend inwardly and are each pivotally connected to the forward chassis structure 4 so as to allow a vertical pivoting motion of the suspension arms 17. Two extendable shock absorbers 16 are each pivotally connected to a respective suspension arm 17 at a first end and to the forward chassis structure 4 at the other end. The shock absorbers 16 provide absorption of shock loads to the sprung mass of snow vehicle 1.

It should be understood that the illustrated front suspension structure is exemplary only and that any adequate front suspension structure may be used as long as the center of mass of the battery is located at a position forward from the drive shaft that is adjacent to the front end of the endless track and operatively to the electrical motor for activating the endless track.

Referring to Figures 1 and 13, there is shown a rear suspension arrangement 14. The rear suspension arrangement 14 comprises a skid 23 connected to the tunnel 3 through an arrangement of suspension linkages allowing the skid movement in translation and rotation in the XZ plane. A rear-lower suspension linkage 26 is pivotally connected at its lower end to the skid 23 and pivotally connected at its upper end to a rear-upper linkage 24. The rear- upper linkage 24 is pivotally connected at its lower end to the rear-lower linkage 26 and pivotally connected at its upper end to the tunnel 3. A rear-fore suspension 25 linkage is pivotally connected at its lower end to the skid 23 and pivotally connected at its upper end to the tunnel 3. A pair of shock absorbers 33 and each pivotally connected at their lower end to skid 23 and pivotally connected at their upper end to tunnel 3. The pair of shock absorbers 33 provides absorption of shock loads to the sprung mass of snow vehicle 1. A set of rear tensioning wheels 28 is rotatably connected at a rearmost point to the skid 23.

It should be understood that the illustrated rear suspension structure is exemplary only and that any adequate rear suspension structure may be used as long as the center of mass of the battery is located at a position forward from the drive shaft that is adjacent to the front end of the endless track and operatively to the electrical motor for activating the endless track.

The endless track 5 is positioned below and at least partially within the tunnel 3 and surrounds the rear suspension arrangement 14. The endless track 5 is held under tension by the set of rear tensioning wheels 28, a set of idler wheels 29, a drive shaft 7 and is in contact with the lowermost surface of skid 23. As described below, upon activation of the electric motor 11, the endless track 5 rotates and propels the electric snow vehicle 1.

The drive shaft 7 is rotatably secured to the chassis of the electric snow vehicle 1 such as to the tunnel 3 and is operatively connected to the electric motor 11 so that the activation of the electric motor 11 triggers a rotation of the drive shaft 7. The drive shaft 7 is further operatively connected to the endless track 5 so that a rotation of the drive shaft 7 causes a rotation of the endless track 5.

In the illustrated embodiment, the electrical motor 11 is provided with an upper pulley 9 and a lower pulley 8 is fixedly secured to the drive shaft 7. The upper and lower pulleys 9 and 8 are connected together via a drive belt 10 so that a rotation of the upper pulley 9 causes a rotation of the lower pulley 8, and therefore a rotation of the drive shaft 7.

A sprocket (not shown) is further fixedly secured to the drive shaft 7. The sprocket engages the endless track 5 so that a rotation of the drive shaft 7 causes a rotation of the sprocket and a motion of the endless track 5.

The drive shaft 7 extends longitudinally along a longitudinal axis which is substantially orthogonal to the longitudinal axis of the tunnel 3. Furthermore, the drive shaft is positioned within the space or boundary 50 defined by the endless track 5 and is located adjacent to the front end of the endless track 5 In the illustrated embodiment, the axis 52 represents a vertical axis that passes by the center of the drive shaft 7. It should be understood that, when the electric snow vehicle 1 is positioned on a horizontal surface, a vertical axis is an axis that is orthogonal to the horizontal surface. Alternatively, the vertical axis 52 could be aligned with the front end point of the drive shaft 7, i.e. aligned with the point of the drive shaft 7 that is the closest to the ground engaging members 27.

Similarly, the vertical axis 51 is a vertical axis that is aligned with the forwardmost end of the endless track 5, i.e. aligned with the point of the endless track 5 that is the closest to the ground engaging members 27. The position of the center of mass 53 of the battery 6 along the longitudinal axis of the chassis, i.e. along the longitudinal axis of the channel 3, is chosen so as to be forward to the drive shaft 7, i.e. forward to the vertical axis 52. It should be understood that the center of mass 53 of the battery 6 is defined as the mass-based centroid of all components contained within the battery 6. In one embodiment, the position of the center of mass 53 of the battery 6 along the longitudinal axis of the chassis is chosen so as to be forward to the endless track 5, i.e. forward to the vertical axis 51.

The electric motor 11 is electrically connected to a control module 12 through cables 13. The control module 12 is connected to the battery 6 via cables 30. The control module 12 receives vehicle input data from input sensors and DC current from the battery pack 6. As known in the art, the DC current is modulated according to a control algorithm and transmitted to the electric motor 11 which transforms the electrical energy into a tractive torque. The electric motor 11 is operatively connected to the endless track 5 so that the tractive torque produced by the electric motor 11 be transmitted to the endless track 5, as described above.

In one embodiment, the battery pack 6 of the snow vehicle 1 represents a significant proportion of the total mass of the vehicle. The placement of the battery pack 6 influences the location of the overall center of mass of the snow vehicle 1. Generally, in a terrestrial vehicle, the longitudinal location of the center of mass has an effect on the handling characteristic of the vehicle. A center of mass which is forward-biased will induce an under-steering handling behavior while a center of mass which is rearwards biased will induce an over-steering handling behavior. An exaggerated biasing of the center of mass location in either direction may result in a snow vehicle 1 which may be difficult to control.

In one embodiment, the height of the center of mass in any terrestrial vehicle may influence the cornering capacity of the vehicle. A vehicle which has a high center of mass can undergo a limited lateral acceleration before it risks rolling over, depending on the balance of lateral inertial moments about the outermost point of contact of the vehicle with the ground. In most cases vehicle rollover is highly undesirable since it may result in instability, loss of control and a possible crash. By lowering the center of gravity of the vehicle, a user is required to provide less effort to counteract the rollover tendency in cornering.

Similarly, the height of the center of mass in any terrestrial vehicle may influence the pitching behavior of the vehicle. A vehicle which has a high center of mass can undergo limited longitudinal acceleration before its forward contacting members lose contact with the ground (referred to as ski-lift for a snow vehicle), depending on the balance of longitudinal inertial moments about the rearmost point of contact of the vehicle with the ground. In most cases ski lift is undesirable since it results in a reduction of cornering capacity. By lowering the center of gravity of the vehicle, a user is required to provide less effort to counteract the ski-lift tendency on acceleration.

While in a conventional electric snow vehicle, the battery pack is usually positioned above the endless track, the design of the present electric snow vehicle 1 may allow to lower the center of mass of the vehicle by lowering the center of mass of the battery. This may be performed by lowering the location of the center of mass 53 of the battery 6. The lowering of the center of mass 53 of the battery 6 may be performed by placing center of mass 53 of the battery 6 forwardly to the forwardmost point 51 of the endless track 5 since it is no longer restrained to lie above the endless track 5. By lowering the center of mass 53 of the battery 6 in comparison conventional electric snow vehicles, it is also possible to lower the overall center of mass of the electric snow vehicle, thereby resulting in a more stable behavior for the electric snow vehicle 1 in comparison to that of a conventional snow vehicle.

In one embodiment, the center of mass 53 of the battery 6 is located less than 500 mm ahead of the front end point 51 of the endless track 5 along the longitudinal axis of the vehicle 1. In the same or another embodiment, the center of mass 53 of the battery 6 is located between about 500 mm below the topmost point of the endless track 5 and about 400 mm above the topmost point of the endless track 5 along the vertical axis. Such a location for the center of mass 53 may represent a tradeoff between roll and pitch stability, thereby providing a balanced longitudinal weight distribution in comparison to a conventional electric vehicle.

Figures 3a, 3b and 3c each illustrate a different shape for a battery pack or battery pack 6b, 6c, 6d, respectively. The battery 6b has a rectangular cross-sectional shape while the battery 6c has an L-shaped cross-section. The battery 6c is provided with a substantially diamond shape.

Figures 4a, 4b, 4c and 4d each illustrate the internal components for the battery pack 6a, 6b, 6c and 6d, respectively.

The battery pack 6a, 6b, 6c, 6d comprises of at least an enclosure 77, a power interface 75, a plurality of battery modules 100 and supporting electrical components. In one embodiment, the battery pack 6a, 6b, 6c, 6d provides at least 5 kilowatt-hours (kWh) of total electric charge so as to be capable to propel the snow vehicle 1.

The enclosure 77 provides mounting and environmental protection for all components contained in the battery pack 6a, 6b, 6c, 6d. As illustrated in Figures 5-8, a power interface 75 controls the distribution of the battery pack electrical current to the components located outside of the enclosure 77. Leader cables 76 carry electrical current from the power interface 75 to module terminals 251 via disconnectable connectors 25 Od. Module interconnectors 250 carry electrical current from one battery module 100 to another battery module 100 via module terminals 251. It should be understood that the configuration of the leader cables 76 and the module interconnectors 250 determine the overall voltage supplied by battery pack 6a, 6b, 6c, 6d.

Figure 9 illustrates exemplary battery cells presented as prismatic cells 201a. Prismatic cells 201a are composed of a combination of materials laminated in a pouch format, allowing them to store energy and to provide an electrical potential and current. The prismatic cells are interfaced through prismatic cell tabs 202. Figure 10 illustrates exemplary battery cells presented as cylindrical cells 201b. Cylindrical cells 201b are composed of a combination of materials laminated in a cylindrical format, allowing them to store energy and to provide an electrical potential and current. In one embodiment, cells 201 operate on the basis of lithium-polymer chemistry. However, it should be understood that any adequate cell may be used.

As illustrated in Figures 4a and 5, the battery pack 6a may comprise a plurality of prismatic modules 100 arranged in a horizontal single-row layout. As illustrated in Figures 4b and 6, the battery pack 6b may comprise a plurality of modules 100 arranged in a multiple-row layout of modules 100 oriented in their upright position. As illustrated in Figures 4c and 7, the battery pack 6c may comprise a plurality of modules 100 arranged in a multiple- row layout of modules 100 oriented in their inclined position. As illustrated in Figures 4d and 8, the battery pack 6d may comprise a plurality of cylindrical-cell modules 214 interconnected by cylindrical cell bolted bus-bars 257a.

In one embodiment, a prismatic cell module 100 may comprise a plurality of rectangular prismatic cells 201a, a pair of end-plates 101 secured together by fastening rods 103 and fastening nuts 104, a pair of module terminals 105 and of a cover 106, as illustrated in Figure 9. Cells 201a contained in the module are connected together via permanent cell interconnectors 203. Module terminals 105 allow the module 100 to be non-permanently connected to other elements such as to be serviceable by means of the disconnectable interconnectors 250. In another embodiment, a cylindrical cell module 214 may comprise a plurality of cylindrical cells 201b contained in a cylindrical cell frame 215, as illustrated in Figure 10. The cylindrical cells 201b are electrically connected together by permanent inter connectors 209. Two interconnectors 257a removably connect cylindrical cells module 214 to external components.

In one embodiment, a permanent prismatic cell electrical interconnector 203a comprises two prismatic cell tabs 202 connected together by a soldered interface material 205, as illustrated in Figure 11a. Prismatic cell tabs 202 carry electrical current into the body of the prismatic cell 201a. In another embodiment, a permanent prismatic cell electrical interconnector 203b comprises two prismatic cell tabs 202 connected together by a welded interface 206 in which no interface material is present, as illustrated in Figure l ib. In a further embodiment 203 c, a permanent prismatic cell electrical interconnector comprises two prismatic cell tabs 202 connected to each other by a rivet 207, as illustrated in Figure 11c. Clamping load exerted by rivet 207 is spread out by rivet washers 208. In one embodiment, a permanent cylindrical cell interconnector 204a consists of a cylindrical interconnect bar 209 connected to a plurality of cylindrical cells 201b by a soldered interface material 205, as illustrated in Figures l id. In another embodiment, a permanent cylindrical cell interconnector 204b comprises a cylindrical interconnect bar 209 connected to a plurality of cylindrical cells 201b by a welded interface 206, as illustrated in Figure l ie.

In some embodiments, disconnectable interconnectors 250 provide electrical connections between elements in a removable or non-permanent manner so as to be serviceable. For example, a disconnectable interconnector 250a connects two cells 201 via their respective cell tabs 202, which are each welded to a bus-bar 257 at a weld interface 203, the bus-bars 257 being connected to each other by a bolted connection, as illustrated in Figure 12a. A bolt 255 and nut 256 ensure a reliable electrical connection.

In another example, a disconnectable interconnector 250b connects two cells 201 via their respective cell tabs 202, which are each welded to a respective bus-bar 257 at a weld interface 203, the bus-bars 257 being connected together by a cable 254, as illustrated in Figure 12b. A bolt 255 and nut 256 ensure a reliable electrical connection at each end of the cable 254. The cable 254 is affixed to the bolt 255 by means of crimped cable lugs 253.

In a further example, a disconnectable interconnector 250c connects together two cells 201 via their respective cell tabs 202, which are each welded to a respective terminal 251 at a weld interface 203, the terminals being connected to each other by a cable 254 and friction- fit adapters 252, as illustrated in FIG. 12c. The friction fit adapters 252 are removably connected to the terminals 251 by means of a friction-fit interface. The cable 254 is affixed to friction-fit adapters 252 by means of a permanent connection.

The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.

Claims

I/WE CLAIM:

1. An electric snow vehicle comprising: a chassis extending longitudinally between a front chassis end and a rear chassis end along a longitudinal axis; an endless track operatively connected to the chassis to move the electric snow vehicle, the endless track extending between a front track end and a rear track end; at least one ground engagement member disposed adjacent to the front chassis end and operatively secured to the chassis; an electric motor; a drive shaft operatively connected to the electric motor and to the endless track for activating the endless track, the drive shaft being rotatably secured to the chassis adjacent to the front track end of the endless track between the front and rear track ends; a battery securable to the chassis and connectable to the electric motor for powering the electric motor and thereby triggering an activation of the endless track to move the electric snow mobile, the battery being positionable so that a center of mass of the battery be located at a given position along the longitudinal axis of the chassis, the given position being in forward position relative to drive shaft.

2. The electric snow mobile of claim 1, wherein the given position for the battery is in forward position relative to the front track end of the endless track.

3. The electric snow mobile of claim 1 or 2, wherein the battery is further positionable so that the center of mass of the battery be located between about 500 mm below a topmost point of the endless track and about 400 mm above the topmost point of the endless track along a vertical axis, the vertical axis being orthogonal to the longitudinal axis.

4. The electric snow mobile of any one of claims 1 to 3, wherein the center of mass of the battery is located less than 500 mm ahead of the front track end of the endless track, along the longitudinal axis.

5. The electric snow mobile of any one of claims 1 to 4, further comprising a battery cradle for receiving the battery, the battery cradle being positioned and designed so that, when the battery is received therein, the center of mass of the battery is located in the forward position relative to the front track end.

6. The electric snow mobile of any one of claims 1 to 3, wherein the whole battery is positionable forward relative to the drive shaft.

7. The electric snow mobile of any one of claims 1 to 5, wherein the whole battery is positionable forward relative to the front track end of the endless track.

8. The electric snow mobile of any one of claims 1 to 4, wherein a portion of the battery may overlap the endless track.

9. The electric snow mobile of any one of claims 1 to 8, wherein the ground engaging member comprises at least one ski.

10. The electric snow mobile of any one of claims 1 to 9, wherein the battery has an electric charge of at least 5 kilowatt-hours.

11. The electric snow mobile of any one of claims 1 to 10, wherein the battery comprises a battery pack.

12. The electric snow mobile of claim 11, further comprising a power interface for controlling a distribution of an electrical current delivered by the battery pack.

13. An electric snow vehicle comprising: a chassis extending longitudinally between a front chassis end and a rear chassis end along a longitudinal axis; an endless track operatively connected to the chassis to move the electric snow vehicle, the endless track extending between a front track end and a rear track end; at least one ground engagement member disposed adjacent to the front chassis end and operatively secured to the chassis; an electric motor; a drive shaft operatively connected to the electric motor and to the endless track for activating the endless track, the drive shaft being rotatably secured to the chassis adjacent to the front track end of the endless track between the front and rear track ends; a battery secured to the chassis and connected to the electric motor for powering the electric motor and thereby triggering an activation of the endless track to move the electric snow mobile, the battery being positioned so that a center of mass of the battery be located at a given position along the longitudinal axis of the chassis, the given position being in forward position relative to drive shaft.

14. The electric snow mobile of claim 13, wherein the given position for the battery is in forward position relative to the front track end of the endless track.

15. The electric snow mobile of claim 13 or 14, wherein the battery is further positioned so that the center of mass of the battery be located between about 500 mm below a topmost point of the endless track and about 400 mm above the topmost point of the endless track along a vertical axis, the vertical axis being orthogonal to the longitudinal axis.

16. The electric snow mobile of any one of claims 13 to 15, wherein the center of mass of the battery is located less than 500 mm ahead of the front track end of the endless track, along the longitudinal axis.

17. The electric snow mobile of any one of claims 13 to 16, further comprising a battery cradle for receiving the battery, the battery cradle being positioned and designed so that, when the battery is received therein, the center of mass of the battery is located in the forward position relative to the front track end.

18. The electric snow mobile of any one of claims 13 to 15, wherein the whole battery is positionable forward relative to the drive shaft.

19. The electric snow mobile of any one of claims 13 to 17, wherein the whole battery is positionable forward relative to the front track end of the endless track.

20. The electric snow mobile of any one of claims 13 to 16, wherein a portion of the battery may overlap the endless track.

21. The electric snow mobile of any one of claims 13 to 20, wherein the ground engaging member comprises at least one ski.

22. The electric snow mobile of any one of claims 13 to 21, wherein the battery has an electric charge of at least 5 kilowatt-hours.

23. The electric snow mobile of any one of claims 13 to 22, wherein the battery comprises a battery pack.

24. The electric snow mobile of claim 23, further comprising a power interface for controlling a distribution of an electrical current delivered by the battery pack.