Power transmission structure and off-road vehicle

Abstract

Off-road vehicles are prone to high-load driving conditions, which can easily cause belt temperatures to rise. This invention provides a means to prevent belt temperature increases even in such situations. [Solution] The continuously variable transmission 12 comprises a belt transmission mechanism 40 including a drive pulley 50, a driven pulley 70, and a belt 43, and a case 80 including an internal space housing the belt transmission mechanism 40, an intake port 80b for drawing air into the internal space, and an exhaust port 80c for discharging air from the internal space. The case 80 includes a bowl-shaped cup portion 85 housing the drive pulley 50, the cup portion 85 covers at least a part of the rotating portion 59 of the drive pulley 50, the cup portion 85 has a rotating portion facing surface that faces the rotating portion 59 in the radial direction of the rotating portion 59, and the exhaust port 80c opens to the rotating portion facing surface.

Description

Technical Field

[0001] The technology disclosed herein relates to a power transmission structure and an off-road vehicle.

Background Art

[0002] US Patent Application Publication No. 2023 / 0341045 discloses a vehicle having a continuously variable transmission. The continuously variable transmission has a power transmission mechanism and a case for housing the power transmission mechanism. The power transmission mechanism includes a drive pulley, a driven pulley, and a belt. The case includes an air intake for inhaling air and an air exhaust for exhausting air.

Brief Description of the Drawings

[0003] [Figure 1] FIG. 1 is a left side view of a utility vehicle. [Figure 2] FIG. 2 is an exploded perspective view showing the continuously variable transmission as viewed from the left rear. [Figure 3] FIG. 3 is an exploded perspective view showing the continuously variable transmission as viewed from the right rear. [Figure 4] FIG. 4 is a cross-sectional view of the continuously variable transmission cut along a plane including the axis of the drive pulley and the axis of the driven pulley. [Figure 5] FIG. 5 is a cross-sectional view of a portion including the first chamber in the continuously variable transmission as viewed from the left. [Figure 6] FIG. 6 is a cross-sectional view of a portion including the fixed sheave of the drive pulley in the continuously variable transmission as viewed from the left. [Figure 7] FIG. 7 is a cross-sectional view of a portion including the fixed sheave of the drive pulley, the movable sheave of the driven pulley, and the belt in the continuously variable transmission as viewed from the left. [Figure 8] FIG. 8 is a cross-sectional view of a portion including the movable sheave of the drive pulley and the rotating portion of the drive pulley in the continuously variable transmission as viewed from the left.

Modes for Carrying Out the Invention

[0004] The following describes exemplary embodiments in detail with reference to the drawings. Figure 1 is a left side view of the utility vehicle 100. The utility vehicle 100 is capable of traveling off-road. The utility vehicle 100 is an example of an off-road vehicle of the present disclosure. Hereinafter, the utility vehicle 100 will also be simply referred to as "vehicle 100". A utility vehicle is, for example, one that has a cargo bed, a roll-over protective structure (ROPS), or low-pressure tires. A utility vehicle is, for example, a side-by-side vehicle. A utility vehicle may travel on unpaved, uneven terrain. For example, a utility vehicle may travel through wetlands or cross rivers. A utility vehicle may also travel in areas where the water level is located near the seat surface.

[0005] In this disclosure, each component of the vehicle 100 is described using the direction of the vehicle 100. Specifically, "front" means the front of the vehicle 100 in the vehicle's longitudinal direction, and "rear" means the rear of the vehicle 100 in the vehicle's longitudinal direction. "Left" means the left side when the vehicle 100 is facing forward, and "right" means the right side when the vehicle 100 is facing forward. "Vehicle width direction" means the vehicle width direction of the vehicle 100, or in other words, the left-right direction of the vehicle 100, and may also be referred to as "left-right direction". "Inside in the vehicle width direction" means the passenger compartment side in the vehicle width direction, and "outside in the vehicle width direction" means the outside of the vehicle in the vehicle width direction.

[0006] Vehicle 100 comprises a body frame 1, left and right front wheels 3 supporting the front of the body frame 1, and left and right rear wheels 4 supporting the rear of the body frame 1. In other words, Vehicle 100 is a four-wheeled automobile. In this example, the rear wheels 4 are drive wheels. The space between the left and right front wheels 3 is covered from above by a hood 5. Behind the hood 5 are left and right seats 6 supported by the body frame 1. The seats 6 are arranged in one row, but may also be arranged in two rows.

[0007] The seat 6 has a seat portion 6a and a back portion 6b. The seat portion 6a supports the occupant's buttocks. The back portion 6b supports the occupant's back. A seat belt 15 is attached to the vehicle frame 1. The seat belt 15 restrains the occupant to the seat 6. The seat belt 15 is, for example, a three-point seat belt.

[0008] The vehicle frame 1 includes a plurality of hollow pipes, which are connected to each other to form the frame. The vehicle frame 1 has a cabin frame 1a that partitions the passenger compartment 7 where the seats 6 are located. Entrance doors open on both the left and right sides of the passenger compartment 7, and these entrance doors are opened and closed by doors 8. A dashboard 9 is located in front of the seats 6 inside the passenger compartment 7. A handle 10 is attached to the dashboard 9. A cargo bed 2 is located behind the cabin frame 1a. The cargo bed 2 is located above the rear wheels 4. The cargo bed 2 includes a concave loading space 2a that opens upwards.

[0009] Vehicle 100 has an engine 11 and a continuously variable transmission 12. The engine 11 is an example of a power source of this disclosure. The continuously variable transmission 12 is an example of a power transmission structure of this disclosure. The engine 11 and the continuously variable transmission 12 are located behind the seat 6 and below the cargo bed 2. The engine 11 and the continuously variable transmission 12 are facing the bottom surface 2b of the cargo bed 2. Vehicle 100 may also have a generator that generates electricity using the power of the engine 11, and a battery that stores the electricity generated by the generator.

[0010] Engine 11 generates power. Engine 11 is, for example, a reciprocating engine. Engine 11 has a casing, a piston, and a crankshaft. The piston and crankshaft are located inside the casing. The crankshaft is connected to the piston and converts the piston's reciprocating motion into rotational motion.

[0011] The continuously variable transmission 12 transmits the power output from the engine 11 to the rear wheels 4. The continuously variable transmission 12 outputs the rotational power supplied from the engine 11 after changing its speed. Specifically, the continuously variable transmission 12 transmits the rotational speed of the rotational power supplied from the engine 11 to the rear wheels 4 by continuously changing its speed. The continuously variable transmission 12 is connected to a CVT intake duct 22 that guides intake air into the case and a CVT exhaust duct 32 that guides exhaust air outside the case.

[0012] The CVT intake duct 22 and CVT exhaust duct 32 are located in the space in front of the cargo bed 2. Specifically, each duct 22, 32 is located behind the seat 6 and in the area in front of the cargo bed 2. In other words, each duct 22, 32 is located in the area between the pillar frame, which is located behind the seat 6 and extends vertically, and the front wall of the cargo bed 2.

[0013] The CVT intake duct 22 and the CVT exhaust duct 32 are arranged side by side in the vehicle width direction, at least in part. Specifically, the upper part of the CVT exhaust duct 32 is positioned further outward in the vehicle width direction than the upper part of the CVT intake duct 22.

[0014] The CVT intake duct 22 is connected to the continuously variable transmission 12 and supplies outside air to the CVT 12. The CVT exhaust duct 32 is connected to the CVT 12 and discharges internal air from the CVT 12. Specifically, the CVT 12 has suction blades on a part of the rotating body that rotates when driven. When the CVT 12 is driven, the rotation of the blades draws outside air into the case of the CVT 12 via the CVT intake duct 22. The air drawn into the CVT 12 then cools the inside of the CVT 12, specifically the belt of the CVT 12. After that, the air inside the CVT 12 is discharged to the outside through the CVT exhaust duct 32.

[0015] The CVT intake duct 22 is located in the space in front of the cargo bed 2 and extends vertically. The inlet of the CVT intake duct 22 is located higher than the continuously variable transmission 12. Specifically, the inlet of the CVT intake duct 22 is located above the CVT exhaust duct 32. The inlet of the CVT intake duct 22 is located higher than the seat portion 6a of the seat 6. In this embodiment, the inlet of the CVT intake duct 22 is located higher than the upper end of either the cargo bed 2, the seat belt 15, the back of the seat 6 6b, or the headrest of the seat 6. The inlet of the CVT intake duct 22 opens to the rear. The outlet of the CVT intake duct 22 is connected to the intake port of the case of the continuously variable transmission 12.

[0016] The CVT exhaust duct 32 is positioned in the space in front of the cargo bed 2 and extends in a roughly U-shape vertically. The upper end 32a of the CVT exhaust duct 32 is positioned higher than the continuously variable transmission 12. Specifically, the inlet 321 of the CVT exhaust duct 32 is connected to the exhaust port of the case of the continuously variable transmission 12. The CVT exhaust duct 32 extends upward from the inlet 321 as it proceeds downstream of the exhaust, then folds back at the upper end 32a and extends downward. The outlet 320 of the CVT exhaust duct 32 is located at the bottom of the CVT exhaust duct 32. The inlet 321 of the CVT exhaust duct 32 is located further outward in the vehicle width direction than the outlet 320 of the CVT exhaust duct 32. The upper end 32a of the CVT exhaust duct 32 is positioned higher than the seat portion 6a of the seat 6. In this embodiment, the upper end 32a of the CVT exhaust duct 32 is positioned higher than the upper end of any one of the following: the cargo bed 2, the seat belt 15, the back of the seat 6 6b, or the headrest of the seat 6. Furthermore, the upper end 32a of the CVT exhaust duct 32 is positioned in front of the bottom surface 2b of the cargo bed 2.

[0017] As described above, the CVT exhaust duct 32 extends from upstream to downstream of the airflow, above the bottom surface 2b of the cargo bed 2, then folds back and extends downward. Thus, the CVT exhaust duct 32 extends while folding back and curving in a U-shape. The upstream and downstream sides of the CVT exhaust duct 32 are folded back side by side in the vehicle width direction. Specifically, the CVT exhaust duct 32 has a bend in its path that extends upward from upstream to downstream and then extends downward. The upper end 32a of the CVT exhaust duct 32 is located at the bend. The CVT exhaust duct 32 is located upstream of the outlet 320, specifically the upper end 32a is located above the outlet 320.

[0018] The outlet 320 of the CVT exhaust duct 32 is located below the bottom surface 2b of the cargo bed 2. In this embodiment, the outlet 320 is positioned higher than the continuously variable transmission 12. The outlet 320 is located above a portion of the engine 11. The outlet 320 opens toward the engine 11, for example, toward the exhaust pipe of the engine 11. The engine 11 is an example of a cooling object in this disclosure. As a result, the air discharged from the outlet 320 is blown toward the exhaust pipe of the engine 11 to cool the exhaust pipe of the engine 11.

[0019] In this embodiment, the CVT intake duct 22 and the CVT exhaust duct 32 are connected to each other and formed into a unit. Specifically, the CVT intake duct 22 and the CVT exhaust duct 32 are fixed to each other by a plurality of fastening points.

[0020] Figure 2 is an exploded perspective view showing the continuously variable transmission 12 from the left rear. Figure 3 is an exploded perspective view showing the continuously variable transmission 12 from the right rear. Figure 4 is a cross-sectional view of the continuously variable transmission 12 cut in a plane including the axis X1 of the drive pulley 50 and the axis X2 of the driven pulley 70. The continuously variable transmission 12 has a belt transmission mechanism 40 and a case 80 that houses the belt transmission mechanism 40.

[0021] First, the belt transmission mechanism 40 will be described. The belt transmission mechanism 40 includes a driving pulley 50, a driven pulley 70, and a belt 43.

[0022] The driving pulley 50 is supplied with rotational power from the engine 11. Specifically, the driving pulley 50 is connected to the engine 11 via the input shaft 41. The input shaft 41 is, for example, a crankshaft. The axis X1 of the driving pulley 50 coincides with the axis of the input shaft 41.

[0023] The driven pulley 70 outputs torque to the rear wheels 4. Specifically, the driven pulley 70 is connected to the rear wheels 4 via the output shaft 42. The output shaft 42 is, for example, a drive shaft. The axis X2 of the driven pulley 70 coincides with the axis of the output shaft 42. Note that the output shaft 42 may be the input shaft of a subtransmission (gear transmission) connected to the rear wheels 4.

[0024] The belt 43 is wound between the driving pulley 50 and the driven pulley 70. The belt 43 is a so-called V-belt. Specifically, the width of the inner peripheral side of the belt 43 is smaller than the width of the outer peripheral side of the belt 43.

[0025] The torque (rotational power) of the engine 11 is transmitted to the driving pulley 50 via the input shaft 41, the rotation of the driving pulley 50 is transmitted to the driven pulley 70 via the belt 43, and the rotation of the driven pulley 70 is transmitted to the rear wheels 4 via the output shaft 42. In this way, the belt transmission mechanism 40 transmits the torque of the engine 11 to the rear wheels 4.

[0026] Also, the driving pulley 50 is configured to be able to change the radial position where the belt 43 is wound. The driven pulley 70 is configured to be able to change the radial position where the belt 43 is wound. By changing the winding position of the belt 43 on each pulley 50, 70, the amount of angular displacement of the driven pulley 70 while the driving pulley 50 makes one rotation changes. Thereby, the belt transmission mechanism 40 shifts the rotational speed of the engine 11 and transmits it to the rear wheels 4.

[0027] The drive pulley 50 has a fixed sheave 52 and a movable sheave 53. The fixed sheave 52 and the movable sheave 53 are facing each other.

[0028] Multiple air intake blades 521 are provided on the back of the fixed sheave 52 opposite to the movable sheave 53. The case 80 of the continuously variable transmission 12 is provided with an intake port 80b that communicates with the CVT intake duct 22, located opposite the blades 521. As the fixed sheave 52 rotates, centrifugal force causes the air around the fixed sheave 52 to flow radially outward, thereby drawing external air into the case 80.

[0029] The movable sheave 53 changes its position in the direction of the axis X1 in accordance with the rotation of the input shaft 41. The movable sheave 53 moves closer to the fixed sheave 52 as the rotational speed of the input shaft 41 increases. In other words, the higher the rotational speed of the input shaft 41, the further the belt 43 moves radially outward from the drive pulley 50.

[0030] The drive pulley 50 has a rotational mechanism 54 that moves the movable sheave 53 in the direction of the axis X1. The rotational mechanism 54 is located on the opposite side of the movable sheave 53 from the fixed sheave 52. The rotational mechanism 54 can be made of known structures. For example, the rotational mechanism 54 may be a spring mechanism that moves the movable sheave 53 in the direction of the axis X1 by the centrifugal force generated by the rotation of the input shaft 41. For example, such a spring mechanism can be realized by employing a structure such as a centrifugal weight, spring, spider, shaft sleeve, guide rod, or cover located on the opposite side of the movable sheave 53 from the fixed sheave 52.

[0031] The driven pulley 70 has a fixed sheave 72 and a movable sheave 73. The fixed sheave 72 and the movable sheave 73 are facing each other.

[0032] The movable sheave 73 changes its position in the axial direction X2 in accordance with the rotation of the input shaft 41. The movable sheave 73 moves away from the fixed sheave 72 as the rotational speed of the input shaft 41 increases. Specifically, as the rotational speed of the input shaft 41 increases, the tension of the belt 43 increases, and the radially inward force of the belt 43 on the driven pulley 70 increases. As a result, the movable sheave 73 moves away from the fixed sheave 72 in opposition to the spring force, and the belt 43 moves radially inward on the driven pulley 70.

[0033] The case 80 has an internal space 80a, an intake port 80b, and an exhaust port 80c. The internal space 80a houses the belt transmission mechanism 40. The intake port 80b connects the CVT intake duct 22 to the internal space 80a. The exhaust port 80c connects the CVT exhaust duct 32 to the internal space 80a.

[0034] Specifically, the case 80 has a case body 81 and a cover 82. The case 80 is located below the cargo bed 2. The case body 81 and the cover 82 align in the direction of the axis X1 to define the internal space 80a that houses the belt transmission mechanism 40. The case body 81 is located on one side of the drive pulley 50 in the direction of the axis X1. The cover 82 is located on the other side of the drive pulley 50 in the direction of the axis X1. More specifically, the case body 81 is located on the engine 11 side (right side in this embodiment). The cover 82 is located on the opposite side of the engine 11 (left side in this embodiment).

[0035] The case body 81 has an opening on the other side of the drive pulley 50 in the direction of the axis X1. The cover 82 has an opening on one side of the drive pulley 50 in the direction of the axis X1. The opening of the cover 82 is opposite to the opening of the case body 81. The cover 82 is attached to the case body 81 by fasteners to close the case body 81.

[0036] The case body 81 includes an air intake port 80b. Figure 4 schematically shows the air intake port 80b. The air intake port 80b is located on the opposite side of the movable sheave 53 from the fixed sheave 52. In this embodiment, the air intake port 80b is arranged to extend in the vertical direction.

[0037] The outlet 221 (see Figure 5) of the CVT intake duct 22 is connected to the intake port 80b of the case body 81. As a result, air is drawn in from the CVT intake duct 22 and guided into the interior of the case body 81.

[0038] The case body 81 includes a first through hole 81a and a second through hole 81b. An input shaft 41 is inserted into the first through hole 81a, and the input shaft 41 is supported on the inner surface of the first through hole 81a via a bearing. An output shaft 42 is inserted into the second through hole 81b, and the output shaft 42 is supported on the inner surface of the second through hole 81b via a bearing.

[0039] The case body 81 houses the fixed sheave 52. The case body 81 includes a fixed sheave facing surface 81c. The fixed sheave facing surface 81c faces the fixed sheave 52 in the radial direction of the fixed sheave 52.

[0040] The cover 82 includes an exhaust port 80c. Figure 4 schematically shows the exhaust port 80c. The exhaust port 80c is located at the front of the case 80. The exhaust port 80c is located on the opposite side of the fixed sheave 52 from the movable sheave 53. The exhaust port 80c overlaps the rotating portion 59 when viewed from the center of the exhaust port 80c. That is, the exhaust port 80c overlaps the rotating portion 59 when viewed from a direction perpendicular to the plane containing the axis X1 of the drive pulley 50 and the axis X2 of the driven pulley 70.

[0041] The exhaust port 80c of the cover 82 is connected to the inlet 321 (see Figure 8) of the CVT exhaust duct 32. As a result, air is exhausted from inside the cover 82 into the CVT exhaust duct 32.

[0042] The cover 82 houses the movable sheave 53 and the rotating part 59. The cover 82 has a cup portion 85. The cup portion 85 protrudes to the other side in the direction of the axis X1 of the drive pulley 50. Specifically, the cup portion 85 protrudes to the side opposite to the engine 11 (the left side in this embodiment). The cup portion 85 houses the movable sheave 53 and the rotating part 59.

[0043] Thus, the case 80 includes a cup-shaped portion 85 that houses the drive pulley 50. The cup portion 85 protrudes in the direction of the axis X1 relative to the remaining portion of the cover 82. The drive pulley 50 is an example of one pulley of the present disclosure. The cup portion 85 covers at least a portion of the rotating portion 59 of the drive pulley 50 that rotates around the axis X1 of the drive pulley 50. In other words, the cup portion 85 covers the portion of the drive pulley 50 that rotates together with the movable sheave 53. The rotating portion 59 that rotates together with the movable sheave 53 includes a rotational operating mechanism 54 such as a spider, guide rod, and cover. The rotating portion 59 is located on the opposite side of the movable sheave 53 from the fixed sheave 52. The cup portion 85 includes a cylindrical portion formed coaxially with the axis X1 and a lid portion that covers the cylindrical portion from the direction of the axis X1. The cup portion 85 has a rotating portion facing surface 85a that faces the rotating portion 59 in the radial direction of the rotating portion 59. In other words, the cylindrical portion of the cup portion 85 covers the rotating portion 59, which rotates together with the movable sheave 53, from the radial outside. In this embodiment, the radial dimension of the cup portion 85 decreases as it moves away from the fixed sheave 52 in the direction of the axis X1. Also, as shown in Figure 4, the cup portion 85 covers the back surface of the movable sheave 53 when the rotation of the input shaft 41 has stopped. As the input shaft 41 rotates, the movable sheave 53 moves toward the fixed sheave 52 in the direction of the axis X1, so the radial distance between the inner surface of the cup portion 85 and the rotating portion 59 increases as the rotational speed of the input shaft 41 increases.

[0044] The exhaust port 80c described above opens on the surface 85a of the cup portion 85 that faces the rotating part. Specifically, the dimension of the exhaust port 80c in the direction of the axis X1 is formed to be approximately the same as the dimension of the cup portion 85 in the direction of the axis X1. The exhaust port 80c is located above the axis X1 within the cup portion 85. Furthermore, the exhaust port 80c is located closer to the axis X2 of the driven pulley 70 with respect to the axis X1 of the drive pulley 50 within the cup portion 85.

[0045] As shown in Figure 4, the cover 82 houses the fixed sheave 72 and the movable sheave 73 of the driven pulley 70. The cover 82 houses the belt 43. The cover 82 includes a belt-facing surface 82a. The belt-facing surface 82a faces the belt 43 in the radial direction of the belt 43.

[0046] A partition plate 83 is installed inside the case 80. More specifically, the partition plate 83 is installed inside the case body 81. The partition plate 83 extends radially in the direction of the drive pulley 50. The partition plate 83 faces the fixed sheave 52 on one side (the right side in this embodiment) in the direction of the axis X1.

[0047] The partition plate 83 divides the internal space 80a into a first chamber S1 and a second chamber S2. The first chamber S1 is connected to an air intake port 80b. The second chamber S2 is connected to an exhaust port 80c. A belt transmission mechanism 40 is located in the second chamber S2.

[0048] The partition plate 83 includes a communication hole 83a. The communication hole 83a is opposite the inner diameter portion of the fixed sheave 52. The communication hole 83a connects the first chamber S1 to the second chamber S2. The input shaft 41 is inserted into the communication hole 83a.

[0049] Figure 5 is a cross-sectional view of the portion of the continuously variable transmission 12 including the first chamber S1, viewed from the left. In Figure 5, the airflow is indicated by solid arrows. In Figure 5, the first through-hole 81a of the case body 81 is omitted from the drawing. The first through-hole 81a is blocked by the input shaft 41 and the bearing supporting the input shaft 41, and the first chamber S1 does not communicate with the outside through the first through-hole 81a.

[0050] The outlet 221 of the CVT intake duct 22 is connected to the intake port 80b of the case body 81. Air flows from the outlet 221 to the intake port 80b. The intake port 80b includes a first intake port 80b1 and a second intake port 80b2. The first intake port 80b1 is located above the second intake port 80b2.

[0051] The case body 81 includes an inner circumferential surface 81d that defines the first chamber S1. The inner circumferential surface 81d is a surface that faces the first chamber S1 from the radially outward direction perpendicular to the axis X1. The inner circumferential surface 81d is a surface that extends in the circumferential direction about the axis X1. The inner circumferential surface 81d faces the first intake port 80b1 and the second intake port 80b2. The inner circumferential surface 81d has a shape in which the distance L from the axis X1 decreases as it moves away from the first intake port 80b1 in the circumferential direction. The shape of the inner circumferential surface 81d is a so-called scroll shape. The shape of the inner circumferential surface 81d is, for example, non-circular when viewed from the direction of the axis X1.

[0052] Viewed from the direction of the axis X1, the first intake port 80b1 faces the inner circumferential surface 81d, and the second intake port 80b2 faces the communication hole 83a of the partition plate 83. Air flowing in from the first intake port 80b1 passes along the outer diameter side of the communication hole 83a, is guided by the inner circumferential surface 81d, and is drawn from the communication hole 83a into the second chamber S2 (see Figure 4). Air flowing in from the first intake port 80b1 proceeds directly toward the communication hole 83a and is drawn from the communication hole 83a into the second chamber S2.

[0053] Figure 6 is a cross-sectional view of the portion of the continuously variable transmission 12 including the fixed sheave 52, viewed from the left. In Figure 6, the airflow is indicated by solid arrows. In Figure 6, the first through-hole 81a and the second through-hole 81b of the case body 81 are omitted from the drawing. The second through-hole 81b is blocked by the output shaft 42 and the bearing supporting the output shaft 42, so the second chamber S2 does not communicate with the outside through the second through-hole 81b. In Figure 6, the fixed sheave 52 is drawn by a dashed line, and the rotation direction of the fixed sheave 52 (i.e., the rotation direction of the drive pulley 50) is indicated by a dashed arrow.

[0054] The fixed sheave opposing surface 81c is a surface that extends circumferentially around the axis X1. The fixed sheave opposing surface 81c is the inner surface of the case body 81 at which the distance from the outer surface of the fixed sheave 52 in the radial direction is less than or equal to a predetermined value. The inner diameter dimension Rs of the fixed sheave opposing surface 81c from the axis X1 increases as it moves away from the intake port 80b in the rotational direction of the drive pulley 50 (fixed sheave 52). In other words, the inner diameter dimension Rs of the fixed sheave opposing surface 81c increases as it moves downstream of the air.

[0055] As the fixed sheave 52 rotates, the blade 521 rotates, causing air near the communication hole 83a in the second chamber S2 to be sent radially outward. The air flows along the surface 81c opposite the fixed sheave.

[0056] When the blade 521 sends air near the communication hole 83a radially outward, a negative pressure is created near the communication hole 83a in the second chamber S2, and air from the first chamber S1 (see Figure 5) is drawn into the second chamber S2 through the communication hole 83a. The rotation direction of the fixed sheave 52 (counterclockwise in Figure 6) is opposite to the swirling direction of air in the first chamber S1, where air flows downstream around the communication hole 83a (clockwise in Figure 5).

[0057] Figure 7 is a cross-sectional view from the left of the portion of the continuously variable transmission 12 that includes the fixed sheave 52, the movable sheave 73, and the belt 43. In Figure 7, the airflow is indicated by solid arrows. In Figure 7, the rotation direction of the fixed sheave 52 (i.e., the rotation direction of the drive pulley 50), the rotation direction of the movable sheave 73 (i.e., the rotation direction of the driven pulley 70), and the rotation direction of the belt 43 are indicated by dashed-dotted arrows. The rotation directions of the fixed sheave 52, the movable sheave 73, and the belt 43 are the same, and in this example, they are counterclockwise.

[0058] The belt-facing surface 82a is a surface that extends circumferentially around the belt 43. The belt-facing surface 82a is a surface that faces all circumferential directions of the outer surface of the belt 43.

[0059] In Figure 6, the air flowing along the fixed sheave opposing surface 81c moves towards the driven pulley 70 along the inner surface of the cover 82. More specifically, the air in close proximity to the belt 43 flows along the belt opposing surface 82a as the belt 43 moves toward the driven pulley 70, following the movement of the belt 43. At this time, the air cools the belt 43 as it flows along the belt opposing surface 82a.

[0060] In Figure 7, the air that reaches the driven pulley 70 is deflected along the inner surface of the cover 82 and directed toward the drive pulley 50. More specifically, the air that reaches the driven pulley 70 is subjected to a force that moves toward the drive pulley 50 as the driven pulley 70 rotates. In addition, the air that is away from the driven pulley 70 and close to the belt 43 follows the movement of the belt 43 toward the drive pulley 50 and flows toward the drive pulley 50.

[0061] Figure 8 is a cross-sectional view of the continuously variable transmission 12, including the movable sheave 53 and the rotating part 59, viewed from the left. In Figure 8, the airflow is indicated by solid arrows. In Figure 8, the rotation direction of the movable sheave 53 and the rotating part 59 (i.e., the rotation direction of the drive pulley 50) is indicated by dashed arrows. In this example, the rotation direction of the movable sheave 53 and the rotating part 59 is counterclockwise.

[0062] The air that has passed near the driven pulley 70 and approached the drive pulley 50 is given a force that causes it to rotate together with the rotation of the rotating part 59, and rotates along the surface 85a of the cup part 85 that is opposite to the rotating part.

[0063] The rotating portion opposing surface 85a is a surface that extends in the circumferential direction around the axis X1. The rotating portion opposing surface 85a is the inner surface of the cup portion 85 at which the distance from the outer circumferential surface of the rotating portion 59 in the radial direction of the rotating portion 59 is less than or equal to a predetermined value. The inner diameter dimension Rs of the rotating portion opposing surface 85a from the axis X1 increases as it approaches the exhaust port 80c in the rotational direction of the drive pulley 50 (rotating portion 59). In other words, the inner diameter dimension Rs of the rotating portion opposing surface 85a increases as it moves downstream of the air. The shape of the rotating portion opposing surface 85a is a so-called scroll shape. The shape of the rotating portion opposing surface 85a is, for example, non-circular when viewed from the direction of the axis X1.

[0064] The rotating portion 59 has uneven portions 59a with different radial dimensions in the rotational direction of the drive pulley 50. Specifically, the uneven portions 59a are formed by the uneven shapes of the members constituting the rotational operating mechanism 54 when viewed from the direction of the axis X1. For example, the uneven portions 59a are formed by the convex shapes of the spider and guide rod, the concave shapes of the cover, etc.

[0065] The exhaust port 80c opens upward. The exhaust port 80c opens on the upper part of the surface 85a facing the rotating part. The rear end 80c1 of the exhaust port 80c is located behind the axis X1.

[0066] The exhaust port 80c is located on the opposite side of the axis X1 from the separation position 81c1 of the fixed sheave opposing surface 81c when viewed from the direction of the axis X1. In Figure 8, the separation position 81c1 of the fixed sheave opposing surface 81c is indicated by a dot. As shown in Figure 6, the separation position 81c1 of the fixed sheave opposing surface 81c is the position on the downstream side of the air where the inner diameter dimension Rs from the axis X1 of the fixed sheave opposing surface 81c is maximum.

[0067] The air located near the rotating part 59 within the cup portion 85 is rotated around the axis X1 by the rotation of the rotating part 59, and centrifugal force is applied to it, causing it to move along the surface 85a opposite the rotating part towards the exhaust port 80c. At this time, when the rotating part 59 sends the air in the cup portion 85 to the exhaust port 80c, a negative pressure is created inside the cup portion 85, and the air flowing along the surface 82a opposite the belt is drawn into the cup portion 85. Thus, in Figure 7, the air that flows along the surface 82a opposite the belt is moved along the surface 85a opposite the rotating part by the rotation of the rotating part 59 and discharged from the exhaust port 80c.

[0068] The sequence of air flow in the continuously variable transmission 12 in this embodiment is as follows: As shown by the dashed arrows in Figure 2, first, the air that flows into the case 80 from the CVT intake duct 22 passes through the communication hole 83a of the partition plate 83 and flows around the fixed sheave 52 of the drive pulley 50. After that, the air flows around the belt 43 and then around the rotating part 59 of the drive pulley 50 and is discharged into the CVT exhaust duct 32.

[0069] According to the aforementioned continuously variable transmission 12 and vehicle 100, the cup portion 85 of the case 80 covers at least a part of the rotating portion 59 of the drive pulley 50, the cup portion 85 has a surface 85a facing the rotating portion, and the exhaust port 80c opens to the surface 85a facing the rotating portion. As a result, when the drive pulley 50 rotates around the axis X1, the air located in the vicinity of the rotating portion 59 within the cup portion 85 rotates around the axis X1 due to the rotation of the rotating portion 59, and centrifugal force is applied. This encourages the air located within the cup portion 85 to move along the surface 85a facing the rotating portion towards the exhaust port 80c, thereby improving air discharge. In this way, air ventilation within the case 80 can be achieved, and the temperature rise of the belt 43 can be suppressed.

[0070] More specifically, the belt 43 is made of a non-metallic material, such as a resin belt. The belt 43 may experience a temperature rise due to frictional heat generated during power transmission. The belt 43 is particularly prone to temperature increases during power transmission under high load and high rotational speed conditions. In the case of a resin belt, prolonged power transmission at high temperatures may shorten the belt's lifespan or reduce its strength. In this embodiment, outside air is introduced into the case 80, and the heated air within the case 80 is discarded to prevent the belt 43 from rising in temperature.

[0071] Furthermore, since belt 43 is for CVT, it is possible to switch to a gear ratio that transmits a higher load. In addition, utility vehicles that travel on rough terrain experience power transmission under high load conditions as the load on the cargo bed and the number of passengers increase. Off-road vehicles that travel on rough terrain may repeatedly experience power transmission under high load conditions as they overcome obstacles or climb slopes. Thus, off-road vehicles are more prone to high-load driving conditions than vehicles that travel on paved roads, and the belt temperature tends to rise. Even in such cases, this embodiment can prevent the temperature of belt 43 from rising.

[0072] Furthermore, the inner diameter dimension Rr of the rotating part's opposing surface 85a from the axis X1 increases as it approaches the exhaust port 80c in the rotational direction of the drive pulley 50. This allows the air that has moved radially outward due to the rotation of the rotating part 59 to be guided to the exhaust port 80c, thereby improving air discharge efficiency.

[0073] Furthermore, since the rotating part 59 has an uneven surface 59a, the uneven surface 59a can increase the rotational force applied to the air located near the rotating part 59 within the cup portion 85, thereby improving the air discharge efficiency.

[0074] Furthermore, since the rotating part 59 is located on the opposite side of the fixed sheave 52 from the movable sheave 53, the dimensions of the rotating part 59 can be increased in the direction opposite to the fixed sheave 52 in the axial direction X1. This increases the rotational force applied to the air around the rotating part 59, thereby improving air discharge efficiency.

[0075] Furthermore, since the intake port 80b is located on the opposite side of the movable sheave 53 from the fixed sheave 52, the rotation of the fixed sheave 52 makes it easier to draw in air from the intake port 80b, thereby improving ventilation.

[0076] Furthermore, since the intake port 80b is located on the opposite side of the movable sheave 53 from the fixed sheave 52, the intake port 80b is separated from the exhaust port 80c in the direction of the axis X1. This prevents the air drawn in from the intake port 80b from going directly to the exhaust port 80c, thereby promoting temperature exchange between the belt 43 and the air.

[0077] Furthermore, since the exhaust port 80c is located on the opposite side of the separation position 81c1 of the fixed sheave opposing surface 81c relative to the axis X1 when viewed from the direction of the axis X1, it prevents the air drawn in from the intake port 80b from going directly to the exhaust port 80c, thereby promoting temperature exchange between the belt 43 and the air. Specifically, the air drawn in from the intake port 80b is guided to the separation position 81c1 of the fixed sheave opposing surface 52 by the rotation of the fixed sheave 52. On the other hand, since the exhaust port 80c is located on the opposite side of the separation position 81c1 of the fixed sheave opposing surface 81c relative to the axis X1 when viewed from the direction of the axis X1, it prevents the air drawn in from the intake port 80b from going directly to the exhaust port 80c.

[0078] Furthermore, since one of the pulleys is a drive pulley 50, when high torque is transmitted, which is when the belt 43 is likely to get hot, that is, when the movable sheave 53 is separated from the fixed sheave 52, it is possible to increase the area located within the cup portion 85 of the rotating part 59, thereby improving air discharge.

[0079] Furthermore, since the exhaust port 80c opens upward, when connecting the CVT exhaust duct 32 to the exhaust port 80c, it is easier to extend the CVT exhaust duct 32 upward, making it easier to extend the air upstream side of the CVT exhaust duct 32 upward and the air downstream side of the CVT exhaust duct 32 downward. As a result, when the vehicle is driving through wetlands or swamps, foreign matter contained in the wetlands or swamps may be kicked up from the wheels and scattered, and even if foreign matter enters the outlet 320 of the CVT exhaust duct 32, it is difficult for the foreign matter to flow back into the CVT exhaust duct 32 from the outlet 320 towards the exhaust port 80c.

[0080] Furthermore, since the CVT exhaust duct 32 includes a portion located above the outlet 320, when the vehicle is driving through wetlands or swamps, foreign matter contained in the wetlands or swamps may be kicked up from the wheels and scattered, and even if this foreign matter enters the outlet 320 of the CVT exhaust duct 32, it is difficult for the foreign matter to flow back into the CVT exhaust duct 32 from the outlet 320 towards the exhaust port 80c.

[0081] Furthermore, since the rear end 80c1 of the exhaust port 80c is located behind the axis X1, when the CVT exhaust duct 32 is connected to the exhaust port 80c, the amount of protrusion of the CVT exhaust duct 32 forward from the case 80 is reduced.

[0082] Furthermore, the case 80 is located below the cargo bed 2, the exhaust port 80c is located at the front of the case 80, the CVT exhaust duct 32 is positioned in the space in front of the cargo bed 2, and the upper end 32a of the CVT exhaust duct 32 is located in front of the bottom surface 2b of the cargo bed 2. This allows the routing path of the CVT exhaust duct 32 to be shortened.

[0083] Furthermore, since the outlet 320 of the CVT exhaust duct 32 is located below the bottom surface 2b of the cargo bed 2, the outlet 320 of the CVT exhaust duct 32 can be protected by the cargo bed 2, preventing foreign objects above the cargo bed 2 from entering the outlet 320 of the CVT exhaust duct 32. For example, it can prevent rainwater from entering the outlet 320 of the CVT exhaust duct 32.

[0084] Furthermore, since the outlet 320 of the CVT exhaust duct 32 opens toward the engine 11, the air exhaust from the CVT exhaust duct 32 can prevent the engine 11 from overheating.

[0085] Furthermore, since the inlet 321 of the CVT exhaust duct 32 is located further outward in the vehicle width direction than the outlet 320 of the CVT exhaust duct 32, it is easier to connect or disconnect the CVT exhaust duct 32 and the case 80 compared to when the inlet 321 of the CVT exhaust duct 32 is located deep inside the case 80. For example, when removing the cover 82 to replace the belt 43, it is easier to disconnect the CVT exhaust duct 32 and the case 80. It is also preferable that the connection portion between the CVT exhaust duct 32 and the case 80 be formed in a position that is exposed to the side of the vehicle body. This makes it easier to access the connection position between the CVT exhaust duct 32 and the case 80, further facilitating maintenance work such as belt replacement.

[0086] Furthermore, since the upstream and downstream sides of the CVT exhaust duct 32 are folded back side by side in the vehicle width direction, it is possible to easily position a portion of the case 80 in the area between the seat 6 and the cargo bed 2.

[0087] Furthermore, since the CVT intake duct 22 is fixed to the case body 81, there is no need to disconnect the CVT intake duct 22 from the case body 81 when removing the cover 82, thus improving work efficiency.

[0088] Other embodiments As described above, the embodiments described herein have been presented as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments above to create new embodiments. In addition, the components described in the attached drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology. Therefore, the mere presence of such non-essential components in the attached drawings and detailed description should not be immediately assumed to mean that those non-essential components are essential.

[0089] The power transmission structure is a continuously variable transmission 12, but other transmissions may be used. The drive source is an engine 11, but an electric motor or a combined electric motor and engine may be used. The drive wheels are rear wheels 4, but front wheels 3 may be used, or front wheels 3 and rear wheels 4 may be used. The object to be cooled is the exhaust pipe of the engine 11, but other heat-generating parts of the engine 11 may be cooled. Alternatively, other heat-generating components may be used, such as a voltage regulator. Furthermore, sensors or actuators that detect the state of exhaust gas and are located close to heat-generating components may also be objects to be cooled.

[0090] The case 80 may have a cup-shaped cup portion for housing a driven pulley 70, rather than a cup portion 85 for housing a driven pulley 50. In other words, the driven pulley 70 corresponds to one of the pulleys in this disclosure. In this case, the cup portion covers at least a part of the rotating portion of the driven pulley 70 that rotates around the axis X1. The cup portion has a rotating portion facing surface that faces the rotating portion in the radial direction of the rotating portion, and the exhaust port 80c is located on the rotating portion facing surface.

[0091] The rotating part 59 includes, but is not limited to, a rotational operating mechanism 54. For example, it is preferable that the rotating part 59 has irregularities formed to rotate the air. For example, the rotating part 59 may be newly provided with blades for rotating the air. The rotating part may also include a part of the fixed sheave 52 of the drive pulley 50. The rotating part may also be a rotating part that rotates together with the driven pulley 70. In this case, the case 80 has a cup portion that covers at least a part of the driven pulley 70, and the cup portion has a rotating portion facing surface that faces the rotating part in the radial direction of the driven pulley 70, and the exhaust port 80c is located on the rotating portion facing surface. In this embodiment, the same pulley is used to generate the force for drawing in air and the force for drawing out air, but different pulleys may be used to generate the forces for drawing in air and drawing out air.

[0092] The rotating part 59 includes, but is not limited to, a rotational operating mechanism 54. For example, the rotating part may be one of the fixed sheaves 72 or the movable sheaves 73 of the driven pulley 70. In this case, the case 80 has a cup portion that covers one of the sheaves of the driven pulley 70, and the cup portion has a rotating portion facing surface that faces the rotating part in the radial direction of the one sheave, and the exhaust port 80c is located on the rotating portion facing surface.

[0093] The inner diameter dimension Rr of the rotating part facing surface 85a increases as it approaches the exhaust port 80c in the rotational direction of the drive pulley 50, but may remain constant in the rotational direction of the drive pulley 50, or it may decrease as it approaches the exhaust port 80c in the rotational direction of the drive pulley 50.

[0094] The rotating part 59 has a recessed portion 59a, but it does not have to have a recessed portion 59a.

[0095] The rotating part 59 is located on the opposite side of the fixed sheave 52 to the movable sheave 53, but it may also be located on the opposite side of the movable sheave 53 to the fixed sheave 52.

[0096] The exhaust port 80c is located on the opposite side of the fixed sheave 52 from the movable sheave 53, but it may also be located on the opposite side of the movable sheave 53 from the fixed sheave 52. The number of exhaust ports 80c is not limited. As long as at least one exhaust port 80c opens onto the rotating part facing surface 85a, the positions of the other exhaust ports 80c are arbitrary.

[0097] The intake port 80b is located on the opposite side of the movable sheave 53 from the fixed sheave 52, but it may also be located on the opposite side of the fixed sheave 52 from the movable sheave 53. The number of intake ports 80b is not limited. The position of the intake ports 80b is arbitrary.

[0098] The exhaust port 80c is located on the opposite side of the separation position 81c1 of the fixed sheave opposing surface 81c relative to the axis X1 when viewed from the direction of the axis X1, but it may also be located on the same side as the separation position 81c1 of the fixed sheave opposing surface 81c relative to the axis X1.

[0099] The exhaust port 80c is open upwards, but it may also be open forwards, backwards, or downwards.

[0100] The CVT exhaust duct 32 includes a portion located above the outlet 320, but does not necessarily have to include that portion.

[0101] The rear end 80c1 of the exhaust port 80c is located behind the axis X1, but may be located in front of the axis X1, or at the same position as the axis X1.

[0102] The exhaust port 80c is located at the front of the case 80, but it may also be located at the rear of the case 80.

[0103] The CVT exhaust duct 32 is located in the space in front of the cargo bed 2, but it may also be located to the left or right of the cargo bed 2.

[0104] The upper end 32a of the CVT exhaust duct 32 is located in front of the bottom surface 2b of the cargo bed 2, but may also be located in front of the bottom surface 2b of the cargo bed 2.

[0105] The outlet 320 of the CVT exhaust duct 32 is located below the bottom surface 2b of the cargo bed 2, but may also be located above the bottom surface 2b of the cargo bed 2.

[0106] The outlet 320 of the CVT exhaust duct 32 is open toward the object to be cooled (engine 11), but it does not have to be open toward the object to be cooled.

[0107] The inner surface of the cup portion 85 is preferably formed in a scroll shape, but it does not have to be scroll-shaped.

[0108] The continuously variable transmission 12 generates a force that draws air into the case 80 by the fixed sheave 52 of the drive pulley 50, but it is also possible for it not to generate a force that draws air.

[0109] Multiple CVT intake ducts 22 may be provided, or multiple CVT exhaust ducts 32 may be provided. In this case, each of the multiple CVT exhaust ducts 32 may be connected to the cup portion 85, or at least one CVT exhaust duct 32 may be connected to the cup portion 85.

[0110] The CVT intake duct 22 and the CVT exhaust duct 32 do not have to be integrated. Specifically, the CVT intake duct 22, which guides air into the case 80, and the CVT exhaust duct 32, which guides air outside the case 80, may be formed separately.

[0111] Furthermore, the upper ends of the CVT intake duct 22 and CVT exhaust duct 32 are set assuming driving in conditions where the water level is relatively high, but this is not the only consideration. That is, if driving in a dry area is assumed, the upper ends of each duct 22 and 32 may be positioned lower than the seat surface of the seat 6.

[0112] The technologies disclosed herein may be applied to off-road vehicles other than the Utility Vehicle 100.

[0113] [Pattern] The embodiments described above are specific examples of the following embodiments.

[0114] (Aspect 1) The continuously variable transmission 12 (an example of a power transmission structure) comprises a belt transmission mechanism 40 including a drive pulley 50, a driven pulley 70, and a belt 43 wrapped between the drive pulley 50 and the driven pulley 70; an internal space 80a housing the belt transmission mechanism 40; an intake port 80b communicating with the internal space 80a and drawing air into the internal space 80a; and an exhaust port 80c communicating with the internal space 80a and discharging air from the internal space 80a. The case 80 includes a bowl-shaped cup portion 85 that houses one of the drive pulleys 50 or the driven pulley 70, the cup portion 85 covers at least a portion of the rotating portion 59 of the one pulley 50 that rotates around the axis X1 of the one pulley 50, the cup portion 85 has a rotating portion facing surface 85a that faces the rotating portion 59 in the radial direction of the rotating portion 59, and the exhaust port 80c opens to the rotating portion facing surface 85a.

[0115] In this configuration, when one pulley 50 rotates around the axis X1, the air located near the rotating part 59 within the cup portion 85 rotates around the axis X1 due to the rotation of the rotating part 59, and centrifugal force is applied to it. This encourages the air located within the cup portion 85 to move along the surface 85a opposite the rotating part towards the exhaust port 80c, thereby improving air discharge. In this way, air ventilation within the case 80 is achieved, and the temperature rise of the belt 43 can be suppressed.

[0116] (Aspect 2) In the continuously variable transmission 12 described in Embodiment 1, the inner diameter dimension Rr of the rotating portion opposing surface 85a from the axis X1 increases as it approaches the exhaust port 80c in the rotational direction of one of the pulleys 50.

[0117] With this configuration, the air that moves radially outward due to the rotation of the rotating part 59 can be guided to the exhaust port 80c, thereby improving the air discharge efficiency.

[0118] (Aspect 3) In the continuously variable transmission 12 described in Embodiment 1 or Embodiment 2, the rotating portion 59 has an uneven portion 59a with different radial dimensions in the rotational direction of one of the pulleys 50.

[0119] With this configuration, the uneven portion 59a can increase the rotational force applied to the air located near the rotating portion 59 within the cup portion 85, thereby improving the air discharge efficiency.

[0120] (Aspect 4) In the continuously variable transmission 12 described in any one of embodiments 1 to 3, the one pulley 50 includes a movable sheave 53 that can move in the direction of the axis X1 and a fixed sheave 52 whose movement in the direction of the axis X1 is prevented, and the rotating portion 59 is located on the opposite side of the fixed sheave 52 from the movable sheave 53.

[0121] This configuration allows for an increase in the dimensions of the rotating portion 59 in the direction opposite to the fixed sheave 52 in the axial direction X1. This increases the rotational force applied to the air surrounding the rotating portion 59, thereby improving air discharge efficiency.

[0122] (Appendix 5) In the continuously variable transmission 12 described in any one of embodiments 1 to 4, the intake port 80b is located on the opposite side of the movable sheave 53 from the fixed sheave 52.

[0123] This configuration allows for easier intake of air from the intake port 80b through the rotation of the fixed sheave 52, thereby improving ventilation. Furthermore, the intake port 80b is spaced apart from the exhaust port 80c in the axial direction X1. This prevents the air drawn in from the intake port 80b from directly moving towards the exhaust port 80c, thereby promoting temperature exchange between the belt 43 and the air.

[0124] (Aspect 6) In the continuously variable transmission 12 described in any one of embodiments 1 to 5, the case 80 has a fixed sheave facing surface 81c that faces the fixed sheave 52 in the radial direction of the fixed sheave 52, the inner diameter dimension Rs of the fixed sheave facing surface 81c from the axis X1 increases as it moves away from the intake port 80b in the rotational direction of one pulley 50, and the exhaust port 80c is located on the opposite side of the separation position 81c1 from the axis X1 where the inner diameter dimension Rs of the fixed sheave facing surface 81c from the axis X1 is maximum, when viewed from the direction of the axis X1.

[0125] This configuration prevents the air drawn in from the intake port 80b from going directly to the exhaust port 80c, thereby promoting temperature exchange between the belt 43 and the air.

[0126] (Aspect 7) In the continuously variable transmission 12 described in any one of embodiments 1 to 6, the one pulley 50 is the drive pulley 50.

[0127] With this configuration, when high torque is transmitted, which is when the belt 43 is likely to get hot, that is, when the movable sheave 53 is separated from the fixed sheave 52, it is possible to increase the area of ​​the rotating part 59 that is located within the cup portion 85, thereby improving air discharge.

[0128] (Pattern 8) In the continuously variable transmission 12 described in any one of embodiments 1 to 7, the exhaust port 80c is open upward.

[0129] With this configuration, when connecting the exhaust duct 32 to the exhaust port 80c, it is easier to extend the exhaust duct 32 upward, and it is easier to extend the air-upstream side of the exhaust duct 32 upward and the air-downstream side of the exhaust duct 32 downward. As a result, when the vehicle is driving through wetlands or swamps, foreign matter contained in the wetlands or swamps is kicked up from the wheels and scattered, and even if foreign matter enters the outlet 320 of the exhaust duct 32, it is difficult for the foreign matter to flow back into the exhaust duct 32 from the outlet 320 towards the exhaust port 80c.

[0130] (Aspect 9) In the continuously variable transmission 12 described in any one of embodiments 1 to 8, an exhaust duct 32 is connected to the exhaust port 80c, and the exhaust duct 32 includes a portion located upstream of the outlet 320 of the exhaust duct 32 and above the outlet 320.

[0131] With this configuration, when the vehicle travels through wetlands or swamps, foreign matter contained in the wetlands or swamps is kicked up and scattered by the wheels, and even if the foreign matter enters the outlet 320 of the exhaust duct 32, it is difficult for the foreign matter to flow back into the exhaust duct 32 from the outlet 320 toward the exhaust port 80c.

[0132] (Aspect 10) In the continuously variable transmission 12 described in any one of embodiments 1 to 9, the rear end 80c1 of the exhaust port 80c is located behind the axis X1.

[0133] With this configuration, when the exhaust duct 32 is connected to the exhaust port 80c, the amount by which the exhaust duct 32 protrudes forward from the case 80 is reduced.

[0134] (Aspect 11) The utility vehicle 100 (an example of an off-road vehicle) comprises an engine 11 (an example of a drive source), rear wheels 4 (an example of drive wheels), and a power transmission structure that transmits the torque of the engine 11 to the rear wheels 4. The power transmission structure includes a belt transmission mechanism 40 which includes a drive pulley 50, a driven pulley 70, and a belt 43 wrapped between the drive pulley 50 and the driven pulley 70, an internal space 80a which houses the belt transmission mechanism 40, an air intake port 80b which communicates with the internal space 80a and draws air into the internal space 80a, and The device has a case 80 which includes an exhaust port 80c that allows air to pass through and discharges air from the internal space 80a, the case 80 which includes a bowl-shaped cup portion 85 that houses one of the drive pulleys 50 or the driven pulley 70, the cup portion 85 which covers at least a part of the rotating portion 59 of the one pulley 50 that rotates around the axis X1 of the one pulley 50, the cup portion 85 which has a rotating portion facing surface 85a that faces the rotating portion 59 in the radial direction of the rotating portion 59, and the exhaust port 80c which opens to the rotating portion facing surface 85a.

[0135] In this configuration, when one pulley 50 rotates around the axis X1, the air located near the rotating part 59 within the cup portion 85 rotates around the axis X1 due to the rotation of the rotating part 59, and centrifugal force is applied to it. This encourages the air located within the cup portion 85 to move along the surface 85a opposite the rotating part towards the exhaust port 80c, thereby improving air discharge. In this way, air ventilation within the case 80 is achieved, and the temperature rise of the belt 43 can be suppressed.

[0136] (Aspect 12) In the utility vehicle 100 described in embodiment 11, the vehicle further comprises a cargo bed 2 positioned above the rear wheels 4 which are drive wheels, and an exhaust duct 32 connected to the exhaust port 80c, wherein the case 80 is located below the cargo bed 2, the exhaust port 80c is located at the front of the case 80, the exhaust duct 32 is positioned in the space in front of the cargo bed 2, and the upper end 32a of the exhaust duct 32 is located in front of the bottom surface 2b of the cargo bed 2.

[0137] This configuration allows for a shorter routing path for the exhaust duct 32.

[0138] (Aspect 13) In the utility vehicle 100 described in embodiment 11 or embodiment 12, the exhaust duct 32 extends downstream of the air, above the bottom surface 2b of the cargo bed 2, then folds back and extends downward, and the outlet 320 of the exhaust duct 32 is located below the bottom surface 2b of the cargo bed 2.

[0139] With this configuration, the outlet 320 of the exhaust duct 32 can be protected by the cargo bed 2, and foreign objects above the cargo bed 2 can be prevented from entering the outlet 320 of the exhaust duct 32.

[0140] (Aspect 14) In the utility vehicle 100 described in any one of embodiments 11 to 13, the outlet 320 of the exhaust duct 32 opens toward the engine 11 (an example of an object to be cooled).

[0141] With this configuration, the temperature of the engine 11 can be prevented from rising by exhausting air from the exhaust duct 32. [Explanation of symbols]

[0142] 2. Cargo bed 2b Bottom 4. Rear wheels (drive wheels) 11. Engine (power source, object to be cooled) 12. Continuously Variable Transmission (Power Transmission Structure) 32 CVT exhaust duct (exhaust duct) 32a top end 320 Exit 40 Belt transmission mechanism 43 belts 50 Drive pulley (one of the pulleys) 52 Fixed sheave 53 Movable sheave 59 Rotating part 59a Uneven part 70 Driven pulley 80 cases 80a interior space 80b Air intake 80c exhaust port 80c1 rear end 81c Fixed sheave facing surface 81c1 Remote position 85 cup section 85a Rotating part facing surface 100 Utility Vehicles (Off-Road Vehicles) Rr, Rs Inner diameter dimensions X1 Drive pulley axis

Claims

1. A belt transmission mechanism including a drive pulley, a driven pulley, and a belt wrapped between the drive pulley and the driven pulley, The case comprises an internal space for housing the belt transmission mechanism, an intake port communicating with the internal space and drawing air into the internal space, and an exhaust port communicating with the internal space and discharging air from the internal space. The case includes a cup-shaped portion that houses one of the drive pulleys or the driven pulley, and the cup portion covers at least a portion of the rotating part of the one pulley that rotates around the axis of the one pulley. The cup portion has a rotating portion facing surface that faces the rotating portion in the radial direction of the rotating portion, and the exhaust port is an opening on the rotating portion facing surface, thus forming a power transmission structure.

2. In the power transmission structure according to claim 1, A power transmission structure in which the inner diameter dimension of the surface facing the rotating portion from the axis increases as it approaches the exhaust port in the rotational direction of one of the pulleys.

3. In the power transmission structure according to claim 1, The rotating portion is a power transmission structure having uneven portions with different radial dimensions in the rotational direction of one of the pulleys.

4. In the power transmission structure according to claim 1, The aforementioned pulley includes a movable sheave that can move in the axial direction and a fixed sheave whose movement in the axial direction is prevented. The rotating portion is a power transmission structure located on the opposite side of the fixed sheave from the movable sheave.

5. In the power transmission structure according to claim 4, The intake port is a power transmission structure located on the opposite side of the movable sheave from the fixed sheave.

6. In the power transmission structure according to claim 5, The case has a fixed sheave-facing surface that faces the fixed sheave in the radial direction of the fixed sheave, The inner diameter dimension of the fixed sheave opposing surface from the axis increases as it moves away from the intake port in the rotational direction of one of the pulleys. The exhaust port is a power transmission structure located on the opposite side of the distance from the axis to the fixed sheave facing surface where the inner diameter dimension from the axis is maximum, when viewed from the axial direction.

7. In the power transmission structure according to claim 4, The aforementioned pulley is a power transmission structure which is the drive pulley.

8. In the power transmission structure according to claim 1, The aforementioned exhaust port is a power transmission structure that opens upward.

9. In the power transmission structure according to claim 1, An exhaust duct is connected to the aforementioned exhaust port. The exhaust duct is a power transmission structure that includes a portion located upstream of the outlet of the exhaust duct and above the outlet.

10. In the power transmission structure according to claim 1, The rear end of the exhaust port is a power transmission structure located behind the axis.

11. Power source and Drive wheels and The system includes a power transmission structure that transmits torque from the drive source to the drive wheels, The aforementioned power transmission structure is A belt transmission mechanism including a drive pulley, a driven pulley, and a belt wrapped between the drive pulley and the driven pulley, The case includes an internal space for housing the belt transmission mechanism, an intake port that communicates with the internal space and draws air into the internal space, and an exhaust port that communicates with the internal space and discharges air from the internal space. The case includes a cup-shaped portion that houses one of the drive pulleys or the driven pulley, and the cup portion covers at least a portion of the rotating part of the one pulley that rotates around the axis of the one pulley. An off-road vehicle wherein the cup portion has a rotating portion facing surface that faces the rotating portion in the radial direction of the rotating portion, and the exhaust port opens to the rotating portion facing surface.

12. In the off-road vehicle according to claim 11, A cargo bed positioned above the rear wheels, which are the drive wheels, The system further comprises an exhaust duct connected to the aforementioned exhaust port, The case is located below the cargo bed, and the exhaust port is located at the front of the case. An off-road vehicle in which the exhaust duct is located in the space in front of the cargo bed, and the upper end of the exhaust duct is located in front of the bottom surface of the cargo bed.

13. In the off-road vehicle according to claim 12, The exhaust duct extends downstream of the air, above the bottom surface of the cargo bed, then folds back and extends downward, and the outlet of the exhaust duct is located below the bottom surface of the cargo bed in an off-road vehicle.

14. In the off-road vehicle according to claim 13, The outlet of the exhaust duct is an off-road vehicle that opens toward the object to be cooled.

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