snowmobile

Abstract

The present disclosure relates to a brake cooling system integrated with the jack shaft of a snowmobile in which cooling is provided through fluid communication with an interior tunnel region of a tunnel frame of the snowmobile. A braking disc can be mounted on the jack shaft inboard of a side bulkhead plate and a drive belt for transferring torque from the jack shaft to a drive shaft can be located outboard of the side bulkhead plate. The drive shaft can drive rotation of a track within an interior tunnel of the tunnel frame.

Description

1 SNOWMOBILE 5 CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 748,357 filed on January 22, 2025, the disclosure of which is incorporated herein by reference in its entirety. 10 TECHNICAL FIELD The present disclosure relates generally to vehicles. More particularly, the present disclosure relates to off-road vehicles such as snowmobiles. BACKGROUND 15 The present disclosure relates generally to off-road vehicles such as snowmobiles. Snowmobiles are available for various applications and riding styles. Example applications / riding styles include mountain (e.g., deep snow), trail, sport utility and crossover. A typical snowmobile includes a chassis, a front suspension for supporting the chassis relative to skis, a rear suspension for supporting the chassis relative to a track, a powertrain for driving 20 rotation of the track and a steering system for allowing an operator to turn the skis. Example documents disclosing snowmobiles include US Patent Nos. 8,490,731; 9,446,810; 7,353,898; 7,870,920; 11,653,112; 11,286,019; and US Patent Publication No. 2013 / 0032419, the disclosures of which are hereby expressly incorporated by reference herein in their entireties. 25 SUMMARY One aspect of the present disclosure relates to braking systems for vehicles such as snowmobiles having configurations to enhance effective brake cooling. A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of 30 features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.2 BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the present disclosure. A brief description of the drawings is as follows: 5 FIG. 1 is a front, left perspective view of a snowmobile; FIG. 2 is a rear, left perspective view of the snowmobile of FIG. 1; FIG. 3 is a side view of the snowmobile of FIG. 1; FIG. 4 is a front, right perspective view of a snowmobile chassis in accordance with the principles of the present disclosure; 10 FIG. 5 is a front, left perspective view of the snowmobile chassis of FIG. 4; FIG. 6 is a left side view of the snowmobile chassis of FIG. 4; FIG. 7 is a right side view of the snowmobile chassis of FIG. 4; FIG. 8 is a top view of the snowmobile chassis of FIG. 4; FIG. 9 is a front view of the snowmobile chassis of FIG. 4; 15 FIG. 10 is a perspective view of a braking system in accordance with the principles of the present disclosure integrated with the chassis of FIG. 4; FIG. 11 is a top view of the braking system of FIG. 10; FIG. 12 is a perspective view of the braking system of FIG. 10 viewed from above a tunnel frame of the chassis of FIG. 4; a heat exchanger that forms a top of a 20 tunnel frame has been removed to better show an inboard side of the braking system that is exposed to an interior tunnel region of the tunnel frame; FIG. 13 depicts braking system of FIG. 10 viewed from within the interior tunnel region of the tunnel frame to show the inboard side of the braking system; FIG. 14 is a longitudinal cross-sectional view cut through a jack shaft on which 25 the braking system of FIG. 10 is installed; FIG. 15 is another longitudinal cross-sectional view cut through the jack shaft on which the braking system of FIG. 10 is installed, the interior tunnel region as well as the inboard side of the braking system are visible; FIG. 16 is a cross-sectional view cut vertically through the braking system of 30 FIG. 10; FIG. 17 is another cross-sectional view cut vertically through the braking system of FIG. 10;3 FIG. 18 is a perspective view of an outboard side of a right-side bulkhead plate of the chassis of FIG. 4; FIG. 19 is an outboard side view of the right-side bulkhead plate of FIG. 18; FIG. 20 is a perspective view of an inboard side of the right-side bulkhead plate 5 of FIG. 18; FIG. 21 is an inboard side view of the right-side bulkhead plate of FIG. 18; and FIG. 22 is an enlarged perspective view of a portion of the inboard side of the right-side bulkhead plate of FIG. 18. 10 DETAILED DESCRIPTION FIGS. 1-3 depict an example snowmobile 20 having a base construction into which structural aspects of the present disclosure can be incorporated. The snowmobile 20 includes a chassis. A front suspension 32 supports the chassis relative to front skis 34 and a rear suspension 36 supports the chassis relative to a track 38. The front suspension 32 can 15 include control arms 33 and shock absorbing / damping structures. The rear suspension 36 can also include shock absorbing / damping structures. A powertrain is supported by the chassis. The powertrain drives rotation of the track 38 to provide propulsion of the snowmobile 20. The snowmobile includes a steering system 40 for allowing an operator to steer the snowmobile 20. The steering system 40 can include a steering shaft 42 and a handlebar 44 that is manually 20 turned to rotate the steering shaft 42. Steering links 46 are operatively coupled to the steering shaft 42 and to knuckles corresponding to the skis 34 such that the skis 34 are turned in response to rotation of the steering shaft 42 by the handlebar 44. A seat 48 is supported on the chassis behind the handlebar 44 and running board assemblies 50 are coupled to the chassis on opposite sides of the seat 48. An outer shell / body can at least partially cover the chassis, powertrain and 25 other components. FIGS. 4-9 depict a snowmobile chassis 120 in accordance with the principles of the present disclosure that can be used in a snowmobile such as the snowmobile 20 of FIGS. 1-3. The chassis 120 has a length L (see FIG. 8) that extends from a front 122 to a rear 124 of the chassis 120. The chassis 120 defines a central longitudinal axis 126 that extends centrally 30 through the chassis 120 along the length L. The chassis 120 includes a left side 128 and a right side 130. Referring still to FIGS. 4-9, the chassis 120 includes a front suspension frame 132 positioned at the front 122 of the chassis 120. The front suspension frame 132 is configured4 to be coupled to a front suspension (e.g., front suspension 32) adapted for supporting the chassis 120 relative to a pair of skis (e.g., skis 34). The chassis 120 also includes a left-side bulkhead plate 134 and a right-side bulkhead plate 136 respectively positioned at the left and right sides 128, 130 of the chassis 5 120 at an intermediate location along the length L of the chassis 120. The left-side and rightside bulkhead plates 134, 136 extend rearwardly with respect to the front suspension frame 132. The chassis 120 also includes a tunnel frame 138 that extends from the rear 124 of the chassis 120 to the left-side and right-side bulkhead plates 134, 136. The tunnel frame 138 defines an interior tunnel region 139. The chassis 120 further includes an over-structure 140 10 position generally above the left-side and right-side bulkhead plates 134, 136. A width W (see FIGS. 8 and 9) of the chassis 120 extends between the left side 128 and the right side 130 of the chassis 120. A height H (see FIG. 9) of the chassis 120 extends between a bottom of the tunnel frame 138 to a top of the over-structure 140. The orientations of the length L, width W and height H of the chassis 120 correspond to the orientations of the length, width and height 15 of a snowmobile into which the chassis 120 is incorporated. Referring to FIGS. 4 and 5, the tunnel frame 138 includes a left wall 142, a right wall 144 and a top wall 146 that extends between the left and right walls 142, 144. The interior tunnel region 139 is defined between the left and right walls 142, 144 beneath the top wall 146. In certain examples, portions of the top wall 146 are defined by heat exchangers such as a first 20 heat exchanger 148 (see FIGS. 12, 13, 24 and 25) positioned at a front end of the tunnel frame 138 and a second heat exchanger 152 (see FIGS. 14 and 15) defining a portion of the top wall 146. It will be appreciated that engine coolant of an engine cooling system is circulated through the heat exchangers 148, 152 to provide cooling of the engine coolant. In many of the views, the second heat exchanger 152 has been removed to improve the visibility of other components 25 of the snowmobile. It will be appreciated that a track (e.g., track 38) can be positioned at least partially with the interior tunnel region 139 and coupled to the tunnel frame 138 by a rear suspension (e.g., rear suspension 36). As depicted, the left-side bulkhead plate 134 overlaps a forward portion of the left wall 142 of the tunnel frame 138 and the right-side bulkhead plate 136 overlaps a forward portion of the right wall 144 of the tunnel frame 138. Fasteners can be 30 used to secure the left-side bulkhead plate 134 and the right-side bulkhead plate 136 to the tunnel frame 138. A seat (e.g., seat 48) can be mounted above the top wall 146. Referring still to FIGS. 4-9, at least a portion of a snowmobile powertrain is mounted in a region generally between the left-side bulkhead plate 134 and the right-side5 bulkhead plate 136. The powertrain generally includes an engine 151 having a crankshaft 154, a transmission 156 (e.g., a continuously variable transmission (CVT); portions of which are depicted), a jack shaft 158 and a drive shaft 160. The transmission 156 can be located at the left side of the chassis 120 as shown at FIGS. 5 and 6). The drive shaft 160 extends across the 5 width W of the chassis 120 between the left-side and right-side bulkhead plates 134, 136 and is rotatable about a drive shaft axis 162 that extends lengthwise through the drive shaft 160. The drive shaft 160 is configured to interface with the track (e.g., via a track drive sprocket) to drive rotation of the track relative to the tunnel frame 138. The jack shaft 158 also extends across the width of the chassis between the left-side and right-side bulkhead plates 134, 136. 10 The jack shaft 158 is rotatable about a jack shaft axis 164 that extends longitudinally through the jack shaft 158. The drive shaft 160, the jack shaft 158 and the crankshaft 154 are preferably generally parallel to each other. A continuous drive element 166 (e.g., a belt or chain) can be used to transfer torque from the jack shaft 158 to the drive shaft 162. As depicted the continuous drive element 166 is a toothed belt routed about sprockets 168, 170 respectively 15 mounted at ends of the jack shaft 158 and drive shaft 160 (see FIGS. 4 and 7 where the drive element 166 and sprockets 168, 170 are located at an outboard side of the right-side bulkhead plate 136). In operation of the powertrain, torque generated by the engine 151 is transferred from the crankshaft 154 through the transmission 156 to the jack shaft 158 to drive rotation of the jack shaft 158 about the jack shaft axis 164. Torque from the jack shaft 158 is transferred 20 to the drive shaft 160 via the continuous drive element 166 to drive rotation of the drive shaft 160 about the drive shaft axis 162. Engagement between the drive shaft 160 and the track drives rotation of the track relative to the tunnel frame 138 such that the track provides propulsion of the snowmobile. A braking system 172 (see FIGS. 10-17) is integrated with the jack shaft 158 to 25 provide snowmobile braking. The braking system can be a hydraulic braking system. A brake lever coupled to a brake line can be mounted on a handlebar of the snowmobile to allow an operator to actuate the braking system 172. The braking system 172 includes a caliper 176 and a braking disc 178. The caliper 176 includes brake pads 180 between which the braking disc 178 can be compressed / clamped (e.g., via hydraulic pressure) to provide braking. Actuation of 30 the caliper 176 by the operator can be provided through the brake lever and brake line 174. A torque transferring relationship (e.g., splined, hex, etc.) exists between the jack shaft 158 and the braking disc 178 such that the braking disk 178 is rotatable with the jack shaft 158 about the jack shaft axis 164. As best shown at FIGS. 12-17, the braking disc 178 is exposed to the6 interior tunnel region 139 to provide effective cooling of the braking disc 178. As depicted, a first portion (e.g., a lower portion such as a lower half) of the braking disc 178 is exposed to the interior tunnel region 139 as the braking disc 178 rotates. It will be appreciated that as the track is rotated relative to the tunnel frame 138, the track generates airflow within the interior 5 tunnel region 139 which is directed towards and across the first portion of the braking disc 178 to provide cooling of the braking disc 178. Additionally, as the track rotates relative to the tunnel frame 138, the track carries snow / ice that are directed into contact with the first portion of the braking disk 178 to provide additional cooling of the braking disc 178. Referring still to FIGS. 12-17, the tunnel frame 138 defines a frame opening 10 182 for exposing the first portion of the braking disk 178 to the interior tunnel region 139. It be appreciated that the frame opening 182 can be defined through a side (e.g., the right wall 144) and / or through a top (e.g., the top wall 146) of the tunnel frame 138. In the depicted example, a flow control cover 184 is attached to the tunnel frame 138 and functions to block a portion of the frame opening 182 (see FIG. 16). The flow control cover 184 includes a wall 15 185 that defines a plurality of flow control openings 186 that in cooperation with the frame opening 182 expose the lower portion of the braking disc 178 to the interior tunnel region 139. The flow control openings 186 can be sized and arranged to prevent excessive snow, ice or debris from being directed against the braking disc 178. As depicted at FIGS. 14-17, the lower portion of the braking disk 178 is located within a disk cooling region 188 defined between the 20 flow control cover 184 and an inboard side of the right-side bulkhead plate 136. In the depicted example, and inboard side of the lower portion of the braking disc 178 opposes the wall 185 of the flow control cover 184 and an outboard side of the lower portion of the braking disc 178 opposes the inboard side of the right-side pocket plate 136. The braking disc 178 rotates through the disk cooling region 188 as the jack shaft 158 is rotated about the jack shaft axis 25 164. As depicted, the disk cooling region 188 is positioned immediately outside the interior tunnel region 139 and is partially separated from the interior tunnel region 139 by the flow control cover 184. The flow control openings 186 provide fluid communication between the interior tunnel region 139 and the disk cooling region 188 thereby exposing the disk cooling region 188 and the lower portion of the braking disc 178 to the interior tunnel region 139. The 30 flow control openings 186 are defined through a portion of the flow control cover 184 that opposes the inboard side of the lower portion of the braking disc 178 and expose the inboard side of the lower portion of the braking disc 178. When the track is rotated, the track causes air, snow and ice from within the interior tunnel region to flow through the flow control7 openings 186 into the disk cooling region 188 and into contact with the lower portion of the braking disc 178. In other examples, the disk cooling region 188 can be within the interior tunnel region 139. In other examples, flow control openings can be defined directly through a wall 5 (e.g., wall 144) of the tunnel frame 138. The right-side bulkhead plate 136 supports the jack shaft 158 and the drive shaft 160. The drive element 166 is a belt that is located at an outboard side of the right-side bulkhead plate 136. The drive element 166 is routed about the sprockets 168, 170 that are located outboard with respect to the right-side bulkhead plate 136. The braking disc 178 is located 10 inboard with respect to the right-side bulkhead plate 136. The flow control cover 184, the braking disc 178 and the right-side bulkhead plate 136 cooperate to define one or more flow paths from the interior tunnel region 139 (e.g., through the frame opening 182) to the outboard side of the right-side bulkhead plate 136. For example, the braking disc 178 defines disc through-openings 190 and the right-side bulkhead plate 136 defines side openings 192. The 15 frame opening 182, the flow control openings 186, the disc through-openings 190 and the side openings 192 cooperate to define one or more flow paths that extend from the interior tunnel region 139 to the outboard side of the right-side bulkhead plate 136 for allowing air flow generated by rotation of the track to flow from the interior tunnel region 139 across / through the lower portion of the braking disc 178 to the outboard side of the right-side bulkhead plate 20 136. Thus, air flowing into the disk cooling region 188 from the interior tunnel region 139 can exit the disc cooling region 186 in an outboard direction through the right-side bulkhead plate 136 via the disc through-openings 190 and the side openings 192. In certain examples, the right-side bulkhead plate 136 can provide heat shielding of the drive element 166 with respect to heat generated at the braking disc 178. For example, 25 the right-side bulkhead plate 136 can include shielding portions 194 (see FIGS. 10 and 18) positioned between the drive element 166 and the braking disc 178 for shielding the drive element 166 from heat generated at the braking disc 178. It will be appreciated that the braking disc 178 is located inboard of the shielding portions 194 and the drive element 166 is located outboard of the shielding portions 194. The side openings 192 can be offset with respect to the 30 drive element 166. In the depicted example, a plurality (e.g., four) of the side openings 192 are located between first and second ones 194a, 194b of the shielding portions 194. The shielding portions 194a, 194b respectively align with / oppose corresponding portions 166a, 166b of the drive element 1668 Referring to FIG. 12, the flow control openings 186 include a plurality of slots that are spaced-apart with respect to each other in a circumferential orientation with respect to the jack shaft axis 164. The slots are separated by slats 196 of the wall of the flow control cover 184. The slots are elongated in a radial direction with respect to the jack shaft axis 164. In one 5 example, the slots have slot lengths SL in the range of 17-21 millimeters (mm) and slot widths SW in the range of 10-14 mm. In one example, the flow control cover 184 defines a passthrough region including a boundary B that bounds the flow control openings 186 and the slats 196. In certain examples, the pass-through region is 30-70% open. In other examples, the passthrough region is 40-60% open. 10 It will be appreciated that since the braking disc 178 rotates about the jack shaft axis 164 with the jack shaft 158, the entire circumference of the braking disc 178 moves through the disc cooling region 188 to provide cooling. However, at any given moment, only about the lower half of the braking disc is actually within the disk cooling region 188 and exposed to the flow of air and snow from the interior tunnel region 139. 15 The various examples described above are provided by way of illustration only and should not be construed to limit the scope of the present disclosure. Those skilled in the art will readily recognize various modifications and changes that may be made without following the example examples and applications illustrated and described herein, and without departing from the true spirit and scope of the present disclosure. 20

Claims

9 What is claimed is:

1. A snowmobile comprising: a tunnel frame defining an interior tunnel region; a track positioned at least partially within the interior tunnel region; a drive shaft that interfaces with the track to drive rotation of the track relative to the tunnel frame, the drive shaft being rotatable about a drive shaft axis; a jack shaft rotatable about a jack shaft axis; a drive element for transferring torque from the jack shaft to the drive shaft for driving rotation of the drive shaft about the drive shaft axis; and a brake system including a caliper and a braking disc, the braking disc being rotatable with the jack shaft about the jack shaft axis, the braking disc being exposed to the interior tunnel region to provide cooling of the braking disc.

2. The snowmobile of claim 1, wherein the tunnel frame and the braking system are relatively configured such that rotation of the track causes air from within the interior tunnel region to flow across the braking disc to provide cooling of the braking disc.

3. The snowmobile of claim 1, wherein the tunnel frame and the braking system are relatively configured such that rotation of the track causes snow from within the interior tunnel region to be directed into contact with the braking disc to provide cooling of the braking disc.

4. The snowmobile of claim 1, wherein the tunnel frame defines a frame opening for exposing the first portion of the braking disc to the interior tunnel region.10 5. The snowmobile of claim 4, wherein the frame opening is defined through a side and / or top of the tunnel frame.

6. The snowmobile of claim 5, further comprising a flow control cover that attaches to the tunnel frame and blocks a portion of the frame opening, the flow control cover defining a plurality of flow control openings that in cooperation with the frame opening expose the braking disc to the interior tunnel region.

7. The snowmobile of claim 6, further comprising a side bulkhead supporting the jack shaft, wherein the drive element is a belt, wherein the belt is outboard with respect to the side bulkhead, and wherein the braking disc is inboard with respect to the side bulkhead.

8. The snowmobile of claim 7, wherein the side bulkhead defines side openings, wherein the braking disc defines disc through-openings, and wherein the frame opening, the flow control openings, the disc through-openings and the side openings cooperate to define a flow path that extends from the interior tunnel region to an outboard side of the side bulkhead.

9. The snowmobile of claim 8, wherein the side bulkhead includes shielding portions positioned between the belt and the braking disc for shielding the belt from heat generated at the braking disc.

10. The snowmobile of claim 5, wherein the flow control openings include a plurality of slots that are spaced-apart with respect to each other in a circumferential orientation with respect to the jack shaft axis, wherein the slots are separated by slats of the flow control cover, and wherein the slots are elongate in a radial orientation with respect to the jack shaft axis.11 11. The snowmobile of claim 10, wherein the slots have lengths in the range of 17-21 mm and widths in the range of 10-14 mm.

12. The snowmobile of claim 10, wherein the flow control cover defines a pass-through region including a boundary that bounds the flow control openings and the slats, and wherein the pass-through region is 30-70 percent open.

13. The snowmobile of claim 10, wherein the flow control cover defines a pass-through region including a boundary that bounds the flow control openings and the slats, and wherein the pass-through region is 40-60 percent open.

14. A snowmobile comprising: a tunnel frame defining an interior tunnel region; a track positioned at least partially within the interior tunnel region; a drive shaft that interfaces with the track to drive rotation of the track relative to the tunnel frame, the drive shaft being rotatable about a drive shaft axis; a jack shaft rotatable about a jack shaft axis; a drive element for transferring torque from the jack shaft to the drive shaft for driving rotation of the drive shaft about the drive shaft axis; and a brake system including a caliper and a braking disc, the braking disc being rotatable with the jack shaft about the jack shaft axis; and a disc cooling region within the interior tunnel region or in fluid communication with the interior tunnel region, wherein the braking disc rotates through the disc cooling region as the jack shaft is rotated about the jack shaft axis.12 15. The snowmobile of claim 14, wherein the tunnel frame and the braking system are relatively configured such that rotation of the track causes air from within the interior tunnel region to flow through the disc cooling region to provide cooling of the braking disc.

16. The snowmobile of claim 14, wherein the tunnel frame and the braking system are relatively configured such that rotation of the track causes snow from within the interior tunnel region to be directed into the disc cooling region into contact with the braking disc to provide cooling of the braking disc.

17. The snowmobile of claim 14, wherein a lower portion of the braking disc is located in the disc cooling region and an upper portion of the braking disc is located outside the disc cooling region.

18. The snowmobile of claim 17, wherein the lower portion of the braking disc coincides generally with a lower half of the braking disc.

19. The snowmobile of claim 14, wherein the tunnel frame defines a frame opening for providing fluid communication between the interior tunnel region and the disc cooling region.

20. The snowmobile of claim 19, wherein the frame opening is defined through a side and / or top of the tunnel frame.

21. The snowmobile of claim 19, further comprising a flow control cover that attaches to the tunnel frame and blocks a portion of the frame opening, the flow control cover defining a plurality of flow control openings that in cooperation with the frame opening provide fluid communication between the interior tunnel region and the disc cooling region.13 22. The snowmobile of claim 21, further comprising a side bulkhead supporting the jack shaft, wherein the drive element is a belt, wherein the belt is outboard with respect to the side bulkhead, and wherein the braking disc is inboard with respect to the side bulkhead.

23. The snowmobile of claim 22, wherein the side bulkhead defines side openings, wherein the braking disc defines disc through-openings, and wherein the frame opening, the flow control openings, the disc through-openings and the side openings cooperate to define a flow path that extends from the interior tunnel region to an outboard side of the side bulkhead.

24. The snowmobile of claim 23, wherein the side bulkhead includes shielding portions positioned between the belt and the braking disc for shielding the belt from heat generated at the braking disc.

25. The snowmobile of claim 14, wherein a wall defines a plurality of flow control openings for providing fluid communication between the disc cooling region and the interior tunnel region.

26. The snowmobile of claim 25, wherein the flow control openings include a plurality of slots that are spaced-apart with respect to each other in a circumferential orientation with respect to the jack shaft axis, wherein the slots are separated by slats of the wall, and wherein the slots are elongate in a radial orientation with respect to the jack shaft axis.

27. The snowmobile of claim 26, wherein the slots have lengths in the range of 17-21 mm and widths in the range of 10-14 mm.14 28. The snowmobile of claim 25, wherein the wall defines a pass-through region including a boundary that bounds the flow control openings, and wherein the pass-through region is 30-70 percent open.

29. The snowmobile of claim 25, wherein the wall defines a pass-through region including a boundary that bounds the flow control openings, and wherein the pass-through region is 40-60 percent open.

30. The snowmobile of claim 25, further comprising a side bulkhead supporting the jack shaft, wherein the drive element is a belt, wherein the belt is outboard with respect to the side bulkhead, wherein the braking disc is inboard with respect to the side bulkhead, wherein the side bulkhead defines side openings, wherein the braking disc defines disc through-openings and wherein a flow path is defined that extends from the interior tunnel region through at least the flow control openings, the disc through-openings, and the side openings to an outboard side of the side bulkhead.

31. The snowmobile of claim 25, wherein the wall includes at least a portion that opposes an inboard side of a lower portion of the braking disc, and wherein the flow control openings are defined though the portion of the wall that opposes the inboard side of the lower portion of the braking disc.