JP2005247049A - Cooling structure for vehicle transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling structure for a vehicle transmission improved in gas-liquid separating performance and transmission cooling performance. <P>SOLUTION: A heat exchanger 42 is set near the forefront of a vehicle body frame. An induction box 34 is housed in a space below a cover member 15 between the heat exchanger 42 and a steering shaft 80 constituting a steering device, which is disposed in the rear. A run off section 85 in a shape surrounding a part of the steering shaft 80 is formed in a part of the induction box 34, and the steering shaft 80 is passed through this run off section 85. Thus, the induction box 34 is disposed so that a part of it overlaps with a part of the steering shaft 80 in its side view. Furthermore, the induction box 34 is provided with a cooing air inlet 33, and this cooling air inlet 33 is disposed to face a space in the upper part of the cover member 15, which is isolated from the space for housing the heat exchanger 42 by the cover member 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling structure for a vehicle transmission.

  An engine unit in which a belt type continuously variable transmission, which is mounted on a saddle riding type rough terrain vehicle, a motorcycle, or the like, is integrated with an engine body, has a V belt or a belt by heat generated by the operation of the transmission. In order not to adversely affect the seal member, etc., fresh air (outside air) from outside is used as cooling air, for example, through a duct, for example, into a belt case in which the transmission is accommodated, and after cooling each member in the interior, For example, a cooling structure for a vehicle transmission that is discharged into the atmosphere via a duct is provided.

  In addition, an induction box with a gas-liquid separation function for outside air is connected to the upstream end of the intake duct to prevent foreign objects such as pebbles, dead grass, and water contained in the outside air from entering the belt case via the duct. Has been.

The induction box is usually placed in front of the vehicle body so that fresh outside air can be introduced. However, in the case of a vehicle equipped with a heat exchanger such as an oil cooler or radiator, the induction box avoids this heat exchanger. It was arranged above the heat exchanger. (For example, refer to Patent Documents 1 and 2.)
JP 2003-90417 A (paragraph numbers [0021] to [0039], FIGS. 5 and 6) JP 2002-274468 A (paragraph numbers [0030], [0042], [0047], FIG. 3 and FIG. 5)

However, if the induction box is arranged above the heat exchanger so as to avoid the heat exchanger, the induction box may move away from the center of gravity of the vehicle body, and the steering performance of the vehicle may be reduced due to the high center of gravity. Depending on the position, the front cover and the front fender that inevitably cover the front of the vehicle body are disposed at a high position, and the sharp appearance of the low front nose is impaired.

  Furthermore, there arises a problem that the outside air temperature around the induction box is raised by the exhaust heat of the heat exchanger.

  Furthermore, as the performance required by the vehicle increases, the heat exchanger increases in size. As a result, the induction box must be installed in the space between the heat exchanger and the steering shaft for steering the front wheels, but in that case, there is a possibility that the capacity of the induction box cannot be secured sufficiently, and a sufficient ventilation area The gas-liquid separation performance deteriorates due to the failure to obtain the transmission, and the cooling performance of the transmission also decreases accordingly.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a cooling structure for a vehicle transmission that improves gas-liquid separation performance and transmission cooling performance.

  In order to solve the above-described problem, a cooling structure for a vehicle transmission according to the present invention includes a rear portion of a steering device and a substantially lower center portion of a vehicle body frame covered with a cover member. An induction duct having an engine unit including a heat exchanger and a transmission integrally formed therein, and having an induction box having a gas-liquid separation function at an upstream end thereof in a housing portion of the transmission In the cooling structure for a vehicle transmission that guides cooling air from the outside through the exhaust and discharges the cooling air that has cooled each member to the atmosphere through the lead-out duct, the heat exchanger near the forefront of the vehicle body frame And the induction box is accommodated in a space between the heat exchanger below the cover member and the steering shaft constituting the steering device disposed behind the heat exchanger. In addition, a relief part having a shape surrounding a part of the steering shaft is formed in a part of the induction box, and the steering box is passed through the relief part, so that a part of the induction box is seen in a side view. While the induction box is arranged so as to overlap with a part of the steering shaft, the induction box has a cooling air inlet, and the cooling air inlet is separated from the housing space of the heat exchanger by the cover member. In addition, it is arranged as desired in the space above the cover member.

  In order to solve the above-described problem, as described in claim 2, the cooling air suction port is provided at the rear of the upper surface of the induction box, and the air / liquid separation function is provided inside the induction box. A capacity room with a labyrinth structure extending in the direction is formed, the escape portion is formed in the capacity room located below the cooling air inlet, and the upstream end of the introduction duct is connected to the outside air outlet at the bottom of the front capacity room It is a thing.

  Furthermore, in order to solve the above-described problem, as described in claim 3, the cooling air intake port is provided so as to open forward, and the cover member immediately before the cooling air intake port is provided with an intake air intake. While opening the opening toward the front, the opening of the cover member and the cooling air suction port are disposed at a position where they substantially overlap in front view, while the opening of the cover member is disposed on the upper surface of the induction box. On the other hand, a shielding member that forms a predetermined gap around the inside thereof is erected integrally in the width direction of the induction box.

  In order to solve the above-described problem, as described in claim 4, the shielding member has a shape that gently slopes backward from the central portion toward both side ends in a plan view, while the induction box A standing wall different from the shielding member is formed at the lower edge portion of the cooling air inlet.

  Further, in order to solve the above-described problem, as described in claim 5, the upper frame constituting the body frame is disposed substantially horizontally so as to connect the vicinity of the upper ends of the front and rear wheels, and The engine unit is mounted between the front and rear wheels, below the upper frame, below the upper ends of the front and rear wheels, and behind the steering handle that constitutes the steering device, and forms an engine intake system. An air cleaner is arranged so as to project upward from the upper side of the upper frame behind the steering shaft, and the induction box is arranged so as to project upward from the upper side of the upper frame in front of the steering shaft. It is.

  According to the cooling structure for a vehicle transmission according to the present invention, since the capacity of the induction box can be sufficiently secured, the gas-liquid separation performance is improved, and the cooling performance of the belt type continuously variable transmission is also improved.

  In addition, even if the induction box is close to the heat exchanger, the outside air that has risen in temperature due to the exhaust heat of the heat exchanger is not sucked from the cooling air inlet, so that the temperature rise of the cooling air can be suppressed and the belt type continuously variable The cooling performance of the transmission is improved.

  Furthermore, a lightweight air cleaner and an induction box can be arranged at the upper part of the vehicle body, and a power unit with a large mass can be arranged at the lower part of the vehicle body, thereby lowering the center of gravity and improving the steering performance of the vehicle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a right side perspective view showing an example of a saddle riding type vehicle to which the present invention is applied, and FIG. 2 is a same plane perspective view. Further, FIG. 3 is a front perspective view thereof.

  As shown in FIGS. 1, 2 and 3, the saddle riding type vehicle 1 includes a body frame 2 made of, for example, a steel pipe. The body frame 2 includes a pair of left and right upper frames 3 and a lower frame 4, a pair of left and right rear vertical frames 5 that vertically connect the rear ends of the frames 3 and 4, and the rear vertical frame 5 and the lower frame 4. A pair of left and right rear horizontal frames 6 that are connected to each other in the front-rear direction, a pair of left and right front vertical frames 7 that are connected between the upper frame 3 and the lower frame 4 in the front direction, It includes a pair of left and right front horizontal frames 8 that connect the front vertical frame 7 and the front portion of the upper frame 3 in the front-rear direction, and a plurality of bridge members 9 that connect the pair of left and right members. Constructed in a cage shape.

  A straddle-type seating seat 10 is installed above and behind the upper frame 3 constituting the vehicle body frame 2, and a steering handle 11 as a steering device for the vehicle 1 is provided in front of the seat. A pair of left and right front wheels 12 and rear wheels 13 with a wide and low-pressure tire are provided on the front and rear of the body frame 2 via a suspension mechanism (not shown). Further, the upper frame 3 is disposed substantially horizontally so as to connect the vicinity of the upper ends of the front and rear wheels 12 and 13, and the front end portion thereof is bent downward and joined to the vicinity of the front end of the lower frame 4.

  An engine unit 14 is mounted between the front and rear wheels 12 and 13, below the upper frame 3, below the upper ends of the front and rear wheels 12 and 13, and behind the steering handle 11. Further, a steering shaft 80 as another steering device is extended from the base portion of the steering handle 11 toward the front wheel 12 obliquely below the front.

  A front cover 15 as a cover member that covers the upper front of the vehicle body frame 2 is provided at the front of the vehicle body, and a front fender 16 that covers the left and right front wheels 12 is integrally or integrally formed. A rear cover 17 is provided as another cover member that covers the upper rear portion of the frame 2, and a rear fender 18 that covers the left and right rear wheels 13 is formed integrally or integrally. These covers 15 to 18 are, for example, synthetic resin molded products.

  For example, the engine unit 14 includes an engine body 19 and a belt-type continuously variable transmission 20 that are integrally formed. The engine body 19 is, for example, a water-cooled four-cycle single-cylinder engine, and includes a crankcase 21 and a cylinder assembly 22 that is disposed in a forward tilted state in front of the upper surface thereof.

  An engine intake system 23 is disposed in a space surrounded by the upper part of the cylinder assembly 22, the front part of the seating seat 10, and the rear part of the steering shaft 80. The engine intake system 23 is disposed on the rear side of the cylinder head 24 constituting the cylinder assembly 22 via an intake pipe 25, and is disposed above the throttle body 26 and in front of the seating seat 10. And an air cleaner 28 connected to the upstream side of the throttle body 26, and the air cleaner 28 is disposed so as to protrude upward from the upper side of the upper frame 3.

  On the other hand, an engine exhaust system 29 is arranged on one side of the engine body 19, in the present embodiment, on the right side. The engine exhaust system 29 includes an exhaust pipe 30 connected to the front side of the cylinder head 24 and an exhaust muffler device 31 connected to the downstream end of the exhaust pipe 30, and the exhaust pipe 30 is once in front of the cylinder head 24. After extending toward the right and rearward, the right side of the engine unit 14 extends substantially horizontally toward the rear along the upper frame 3 of the vehicle body frame 2 and is a belt type continuously variable transmission. The upper frame 3 is deviated from the inner side to the outer side in the vicinity of the rear upper part 20. Further, the exhaust muffler device 31 is disposed, for example, above the rear wheel 13 and below the rear cover 17 in a side view.

  On the other hand, the belt type continuously variable transmission 20 includes a transmission cooling system 32. The transmission cooling system 32 includes an induction box 34, an introduction duct 37, and a lead-out duct 39 as main components.

  The induction box 34 performs gas-liquid separation of outside air introduced from the outside. The introduction duct 37 connects between the induction box 34 and an air inlet 36 that opens at a front portion of a belt case 35 (described later) that is a housing portion of the transmission 20 in which the belt type continuously variable transmission 20 is housed. Then, cooling air is introduced into the belt case 35.

  Furthermore, the lead-out duct 39 is connected to an exhaust port 38 that opens to the rear part of the belt case 35 and leads the exhaust air after cooling the belt-type continuously variable transmission 20. From the exhaust port 38 of the right rear wheel 13 to the rear and then turn substantially vertically upward near the axle of the right rear wheel 13 and once immediately below the rear end of the seating seat 10 to the right side of the vehicle body. The cooling air discharge port 41 is opened toward the surrounding space of the exhaust muffler device 31 at the most downstream end.

  A heat exchanger 42 (oil cooler, radiator, etc.) of the engine body 19 is installed in front of the steering shaft 80 and in the vicinity of the foremost part of the vehicle body frame 2, and a cooling fan 43 for the heat exchanger 42 is provided behind the heat exchanger 42. Installed.

  FIG. 4 is a longitudinal sectional view of the induction box 34. FIG. 5 is a plan view of the induction box 34. As shown in FIGS. 4 and 5, the induction box 34 is, for example, a synthetic resin molded product, and is provided in a space between the heat exchanger 42 installed in the front portion of the vehicle 1 and the steering shaft 80 below the front cover 15. Be contained. The induction box 34 is disposed so as to protrude upward from the upper side of the upper frame 3. Further, a recess 81 extending in the width direction is formed on the bottom surface of the induction box 34, and the induction box 34 is positioned and fixed by engaging the recess 81 with one of the bridge members 9 of the vehicle body frame 2.

  A cooling air inlet 33 is provided at the rear of the upper surface of the induction box 34 so as to open toward the traveling direction of the vehicle 1, that is, toward the front. Further, an intake opening 82 is also opened forward in the front cover 15 immediately before the cooling air intake 33, and the opening 82 of the front cover 15 and the cooling air intake 33 of the induction box 34 are in front. It arrange | positions in the position which overlaps visually (refer FIG. 3). Furthermore, the cooling air inlet 33 is disposed in a desired manner in the space above the front cover 15 that is separated from the accommodation space of the heat exchanger 42 by the front cover 15.

  A capacity chamber 84 having a labyrinth structure extending in the front-rear direction and performing a gas-liquid separation function by a plurality of plate-like ribs 83 disposed in the front-rear direction is provided inside the induction box 34 located on the downstream side of the cooling air inlet 33. The escape portion 85 is formed in the capacity chamber 84 formed and positioned below the cooling air suction port 33, and the upstream end of the introduction duct 37 is connected to the outside air outlet 86 on the bottom surface of the front capacity chamber 84. A plurality of drainage outlets 87 for draining water are provided on the bottom surface of the front and rear of the capacity chamber 84.

  Further, a relief portion 85 having a shape surrounding the front side of the steering shaft 80 is formed at the center of the rear lower portion of the induction box 34. By passing the steering shaft 80 through the relief portion 85, the induction box 34 is subsequently viewed in side view. A part of the lower part is arranged so as to overlap a part of the steering shaft 80.

  Further, a shielding member 88 is provided on the top surface of the induction box 34 in front of the cooling air inlet 33 of the induction box 34 and the intake opening 82 of the front cover 15 to prevent intrusion of foreign matter such as pebbles, dead grass, and water. Provided. This shielding member 88 forms a predetermined gap 89 around the inside of the intake opening 82 of the front cover 15 so that air is allowed to pass therethrough while a plate-like member is shielded in the width direction of the induction box 34. It is a wall that stands up together.

  Further, the shielding member 88 has a V-shaped or U-shaped shape, for example, as viewed in a plan view, which is gently inclined rearward from the central portion toward both side ends in a plan view. And the standing wall 90 different from the said shielding member 88 is formed in the lower edge part of the cooling air inlet 33 of the induction box 34. As shown in FIG.

  FIG. 6 is a horizontal sectional view of the engine unit 14. As shown in FIG. 6, the crankcase 21 that forms the lower part of the engine body 19 is formed to be separable in the left-right direction, and the crankshaft 49 is disposed horizontally and in front of the interior in the width direction of the vehicle 1. Is done. Further, a piston 52 is slidably provided in a cylinder 51 (cylinder) formed in a cylinder block 50 constituting the cylinder assembly 22. The piston 52 is connected to the crankpin 54 of the crankshaft 49 via a connecting rod 53, and the piston 52 reciprocates in the cylinder axis direction in the cylinder 51, and the reciprocating stroke is connected to the crankshaft 49 via the connecting rod 53. The crankshaft 49 is rotated and moved.

  The belt case 35 in which the belt type continuously variable transmission 20 is housed is disposed on the side of the crankcase 21, in the present embodiment, on the right side in the traveling direction of the vehicle 1. Further, the right side portion of the belt case 35 is covered with a case cover 55.

  The belt type continuously variable transmission 20 is, for example, disposed on the side of the crankshaft 49 on the same axis as the crankshaft 49 and behind the drive pulley shaft 56 in parallel with the drive pulley shaft 56. The driven pulley shaft 57 is provided with a drive pulley 58, and the driven pulley shaft 57 is provided with a driven pulley 59.

  The drive pulley 58 includes a fixed drive face 60 that is fixed to the drive pulley shaft 56 so as to rotate together, and a movable drive face 61 that is provided on the drive pulley shaft 56 so as to be rotatable and slidable in the axial direction. The fixed drive face 60 is disposed on the inner side in the axial direction (upper side in the drawing, that is, on the crankshaft 49 side), and a clutch chamber 63 that houses an automatic centrifugal clutch device 62 described later and a belt type A cooling fan 66 is integrally formed on a surface facing a wall (belt case wall 65) that separates the belt chamber 64 that houses the step transmission 20.

  On the other hand, the driven pulley 59 is also composed of a fixed driven face 67 fixed to the driven pulley shaft 57 so as to rotate and a movable driven face 68 provided on the driven pulley shaft 57 so as to be rotatable and slidable in the axial direction. The fixed driven face 67 is arranged on the outer side in the axial direction (lower side in the figure). A V belt 69 is stretched between the pulleys 58 and 59 so that the rotation of the drive pulley shaft 56 is transmitted to the driven pulley shaft 57.

  The right end of the drive pulley shaft 56 is pivotally supported by a bearing 70 provided inside the case cover 55, and the left end of the drive pulley shaft 56 is a bearing provided on the belt case wall 65 on the side facing the crankcase 21. 71 is pivotally supported. An air inlet 36 is formed on the front surface of the front belt case 35 between the bearing 71 provided on the belt case wall 65 and the fixed drive face 60, to which the downstream end of the introduction duct 37 is connected. On the other hand, an exhaust port 38 to which the upstream end of the lead-out duct 39 is connected is formed on the rear surface of the belt case 35 substantially behind the driven pulley 59, and the vehicle 1 travels between the intake port 36 and the exhaust port 38. A cooling air passage 72 substantially along is formed.

  The crankshaft 49 and the drive pulley shaft 56 are connected to each other by an automatic centrifugal clutch device 62 so that they can be connected and disconnected. When the rotational speed of the engine body 19 reaches a predetermined value, the rotation of the crankshaft 49 is transmitted to the drive pulley shaft 56. The

  The rotation of the drive pulley shaft 56 transmitted to the driven pulley shaft 57 by the V-belt 69 is caused by a rear wheel drive output shaft and a front wheel drive output shaft which are not shown in the drawing via a transmission counter shaft 73 and a bevel gear primary shaft 74. Is transmitted to.

  A rear wheel drive propeller shaft 75 as a drive system is coupled to the rear end of the rear wheel drive output shaft so as to be integrally rotatable with the rear wheel drive output shaft. The rear-wheel drive propeller shaft 75 extends rearward substantially horizontally on the substantially center line of the vehicle 1, and its rear end is connected to the rear-wheel differential device 44. A pair of left and right rear wheel shafts 40 extend from the rear wheel differential device 44 toward the left and right rear wheels 13 and are connected to the left and right rear wheels 13.

  On the other hand, a front wheel drive propeller shaft 76 as a drive system is coupled to the front end of the front wheel drive output shaft via a universal joint 77 so as to be integrally rotatable with the front wheel drive output shaft. The front wheel drive propeller shaft 76 extends substantially horizontally on a substantially center line of the vehicle 1 and has a front end connected to a front wheel differential device 78 which is a drive system. A pair of left and right front wheel shafts 79 extend from the front wheel differential device 78 toward the left and right front wheels 12 and are connected to the left and right front wheels 12.

  That is, the output of the engine body 19 (rotation of the crankshaft 49) is steplessly changed by the belt-type continuously variable transmission 20, and the front and rear wheels are driven via the front wheel driving propeller shaft 76 and the rear wheel driving propeller shaft 75. 12 and 13.

  Next, the operation of this embodiment will be described.

  When the engine body 19 is activated, the cooling fan of the belt-type continuously variable transmission 20 provided integrally with the drive pulley (fixed drive face) of the belt-type continuously variable transmission 20 disposed in the belt case 35 rotates. In order to apply a negative pressure to the introduction duct 37 side, the outside air is sucked into the induction box 34 through the cooling air intake port 33 of the induction box 34 as cooling air, and this cooling air flows from the intake port 36 through the introduction duct 37. It is sucked into the belt type continuously variable transmission 20.

  The cooling air cools each member such as a drive pulley, a driven pulley, and a V-belt inside the belt type continuously variable transmission 20, and then passes from the exhaust port 38 through the lead-out duct 39 to the outside through the cooling air discharge port 41. The When the saddle riding type vehicle 1 travels forward, the traveling wind blowing from the front is pushed into the induction box 34, so the amount of cooling air supplied to the belt type continuously variable transmission 20 increases and the cooling efficiency improves. .

  When the outside air is introduced into the cooling air inlet 33 of the induction box 34, the outside air is exposed to the left and right and upper edges of the shielding member 88 and the intake opening of the front cover 15 as shown by arrows A in FIGS. As shown in an arrow B in FIGS. 4 and 5, foreign matter such as pebbles and dead grass in the outside air flows into the cooling air inlet 33 through a gap 89 formed between the inner edge of the portion 82. It is blocked by the shielding member 88 and does not enter the inside of the induction box 34.

  The outside air guided to the inside of the induction box 34 is separated into air and moisture in a capacity chamber 84 having a maze structure that performs a gas-liquid separation function by a plurality of plate-like ribs 83, and only air is the foremost capacity chamber. 84, the upstream end is connected to the bottom surface, and is sent to the belt case 35, which is a housing portion of the transmission 20 in which the belt-type continuously variable transmission 20 is housed, through the introduction duct 37. Water is drained outside through a plurality of drain outlets 87 provided on the bottom surface.

  A relief portion 85 having a shape surrounding the front side of the steering shaft 80 is formed at the center of the rear lower portion of the induction box 34. By passing the steering shaft 80 through the relief portion 85, the induction box 34 can be partially viewed from the lower side in a side view. Is disposed so as to overlap with a part of the steering shaft 80, the capacity of the induction box 34 can be sufficiently secured even if the induction box 34 is shifted rearwardly away from the heat exchanger 42. As a result, a sufficient ventilation area can be obtained, the gas-liquid separation performance is improved, and the cooling performance of the belt type continuously variable transmission 20 is improved accordingly.

  In addition, since the induction box 34 can be disposed rearward, the induction box 34 approaches the center of gravity of the vehicle body, the steering performance of the vehicle 1 is improved, and the front cover 15 and the front fender 16 that cover the front of the vehicle body are provided. Can be lowered, and a sharp appearance with a low front nose can be obtained.

  Further, the cooling air inlet 33 of the induction box 34 is disposed in the space above the front cover 15 that is separated from the accommodation space of the heat exchanger 42 by the front cover 15, so that the induction box 34 exchanges heat. Even in the vicinity of the heat exchanger 42, the outside air whose temperature has risen due to the exhaust heat of the heat exchanger 42 is not sucked from the cooling air inlet 33. As a result, since the temperature rise of the cooling air is suppressed, the cooling performance of the belt-type continuously variable transmission 20 is improved and the front portion of the induction box 34 can be extended to the heat exchanger 42 to some extent. The capacity of the box 34 can be sufficiently secured, a sufficient ventilation area is obtained, the gas-liquid separation performance is improved, and the cooling performance of the belt type continuously variable transmission 20 is also improved.

  Furthermore, a plate-like shielding member 88 that forms a predetermined gap 89 around the inside of the intake opening 82 of the front cover 15 is integrally provided on the upper surface of the induction box 34 in the width direction of the induction box 34. Thus, it is possible to prevent intrusion of foreign matters such as pebbles, dead grass, and water into the induction box 34.

  Then, the shielding member 88 is gently inclined rearward from the central portion toward both side edges in a plan view, for example, a V-shaped or U-shaped shape in a plan view, thereby improving the foreign matter removing function. In addition, the outside air introduction efficiency is improved and the appearance is also improved.

  In addition, since the standing wall 90 different from the shielding member 88 is formed at the lower edge portion of the cooling air inlet 33 of the induction box 34, the function of removing foreign matters is further improved.

  On the other hand, the upper frame 3 constituting the vehicle body frame 2 is disposed substantially horizontally so as to connect the vicinity of the upper ends of the front and rear wheels 12 and 13, and between the front and rear wheels 12 and 13, below the upper frame 3, The engine unit 14 is mounted below the upper ends of the front and rear wheels 12 and 13 and behind the steering handle 11, and an air cleaner 28 constituting the engine intake system 23 is located above the upper frame 3 behind the steering shaft 80. Further, since the induction box 34 is arranged so as to protrude upward from the upper side of the upper frame 3 in front of the steering shaft 80, the relatively lightweight air cleaner 28 and the induction box 34 can be Is placed in the lower part of the car body. , Lower center of gravity is achieved by improving steering performance of the vehicle 1.

1 is a right side perspective view of a straddle-type vehicle showing an embodiment of a cooling structure for a vehicle transmission according to the present invention. FIG. 2 is a plan perspective view of the saddle riding type vehicle shown in FIG. 1. FIG. 2 is a front perspective view of the saddle riding type vehicle shown in FIG. 1. The longitudinal cross-sectional view of an induction box. The top view of an induction box. The plane sectional view of an engine unit.

Explanation of symbols

1 straddle-type vehicle 2 body frame 3 upper frame (body frame)
11 Steering handle (steering device)
12 Front wheel 13 Rear wheel 14 Engine unit 15 Front cover (cover member)
16 Front fender (cover member)
19 Engine body 20 Belt type continuously variable transmission 28 Air cleaner 32 Transmission cooling system 33 Cooling air inlet 34 Induction box 35 Belt case (transmission housing)
37 Introduction duct 39 Outlet duct 42 Heat exchanger 80 Steering shaft (steering device)
82 Intake opening 84 Capacity chamber 85 Induction box relief 86 Induction box outside air outlet 88 Shield member 89 Clearance 90 between front cover opening and shield member Standing wall

Claims (5)

An engine unit that integrally includes an engine body and a transmission including a heat exchanger is mounted at the rear of the steering device and substantially at the center lower portion of the vehicle body frame that is covered with the cover member. , For vehicles in which cooling air is guided from the outside through an introduction duct having an induction box having a gas-liquid separation function at its upstream end, and the cooling air that has cooled each member is discharged into the atmosphere through the outlet duct In the transmission cooling structure, the heat exchanger is installed in the vicinity of the foremost part of the vehicle body frame, and the steering shaft below the cover member and constituting the steering device disposed behind the heat exchanger; And the escape box having a shape surrounding the steering shaft in a part of the induction box. By forming and passing the steering shaft through the escape portion, the induction box is arranged so that a part thereof overlaps a part of the steering shaft in a side view, while the induction box sucks cooling air And a cooling air intake port disposed in an upper space of the cover member that is separated from the heat exchanger housing space by the cover member. Cooling structure. The cooling air inlet is provided at the rear of the upper surface of the induction box, while a capacity chamber having a labyrinth structure extending in the front-rear direction is formed inside the induction box and performs a gas-liquid separation function, and is provided below the cooling air inlet. 2. The cooling structure for a vehicle transmission according to claim 1, wherein the escape portion is formed in the capacity chamber located and the upstream end of the introduction duct is connected to an outside air outlet on the bottom surface of the front capacity chamber. The cooling air intake port is provided so as to open forward, and an opening for intake is opened forward in the cover member immediately before the cooling air intake port, and the opening of the cover member and the cooling air A shielding member that forms a predetermined gap around the opening of the cover member on the upper surface of the induction box is disposed on the upper surface of the induction box, while being arranged at a position that substantially overlaps the wind inlet in front view. 2. The cooling structure for a vehicle transmission according to claim 1, wherein the cooling structure is integrally provided in a direction. The shielding member has a shape that is gently inclined rearward from the central portion toward both side edges in plan view, and a standing wall different from the shielding member is provided at the lower edge portion of the cooling air intake port of the induction box. The cooling structure for a vehicle transmission according to claim 3 formed. The upper frame constituting the body frame is disposed substantially horizontally so as to connect the vicinity of the upper ends of the front and rear wheels, between the front and rear wheels, below the upper frame, from the upper ends of the front and rear wheels. The engine unit is mounted below and behind the steering handle constituting the steering device, and an air cleaner constituting the engine intake system is disposed so as to protrude upward from the upper side of the upper frame behind the steering shaft. 5. The cooling structure for a vehicle transmission according to claim 1, wherein the induction box is disposed so as to protrude upward from the upper side of the upper frame in front of the steering shaft.

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