JP6331815B2 - Cooling structure for continuously variable transmission - Google Patents

Description

  The present invention relates to a cooling structure for a continuously variable transmission.

  In general, in a scooter type motorcycle, an engine and a transmission including a continuously variable transmission and a centrifugal clutch are integrally configured. A continuously variable transmission, a centrifugal clutch, and the like are accommodated in a case space formed by being surrounded by a transmission case extending from the engine case and a case cover that covers the transmission case.

  The continuously variable transmission transmits the power of a drive pulley driven by a crankshaft of an engine through a belt to a driven pulley that is rotatably arranged on a driven shaft. The centrifugal clutch selectively transmits and disconnects power between the driven pulley of the continuously variable transmission and the driven shaft.

  In the case space, as shown in FIG. 7, the cooling fan 102 provided integrally with the drive pulley 101 rotates, whereby cooling air is introduced into the case space 100 and flows, and this cooling air causes the cooling air to flow. The continuously variable transmission and the centrifugal clutch are cooled.

  In the conventional transmission device, since the space between the transmission case 103 and the case cover and the cooling fan 102 is a narrow region X, the cooling air pressure-fed from the cooling fan 102 is temporarily retained in the region X. It was released in the downstream region Y and the flow velocity was locally increased. As a result, the cooling air pumping efficiency was lowered.

  Therefore, in the cooling structure of the continuously variable transmission described in Patent Documents 1 and 2, the space between the transmission case and the case cover and the cooling fan is gradually expanded in the radial direction of the cooling fan along the rotation direction of the cooling fan. Thus, it has been proposed to gradually increase the volume of this space, thereby preventing the cooling air pumped by the cooling fan from staying and improving the pumping efficiency.

  In the cooling structure of the continuously variable transmission described in this publication, the cooling air flow efficiency toward the drive pulley (for example, the cooling air in the region Z in FIG. 7) of the cooling air by the cooling fan is increased. The flow rate is increased, and the cooling efficiency of the continuously variable transmission and the like is improved.

Japanese Utility Model Publication No. 61-26690 JP 2004-204988 A

  However, in the cooling structure of the continuously variable transmission described in Patent Documents 1 and 2, the space between the transmission case and the case cover and the cooling fan is gradually expanded in the radial direction of the cooling fan along the rotation direction of the cooling fan. By doing so, the volume of this space is gradually increased, so that the transmission case and the case cover are enlarged. For this reason, not only the weight and cost of the transmission device increase, but also problems such as a limited degree of freedom in the layout of oil filters, oil strainers and the like occur.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and can improve the cooling efficiency of the continuously variable transmission by allowing the cooling air to flow smoothly without stagnation and accommodate the continuously variable transmission. An object of the present invention is to provide a cooling structure for a continuously variable transmission that can reduce the size of a case cover.

A cooling structure for a continuously variable transmission according to the present invention is configured such that the power of a drive pulley driven by a crankshaft of an engine provided in a vehicle is passed through a belt to a driven pulley that is arranged to be relatively rotatable with a driven shaft. A continuously variable transmission for shifting and transmitting is provided, and the case cover covers the transmission case extending from the engine case, so that a housing space for accommodating the continuously variable transmission is formed, and the drive pulley is cooled on the case cover side. A cooling structure for a continuously variable transmission that cools the continuously variable transmission by introducing and flowing cooling air into the accommodation space by the rotation of the cooling fan, the inner side of the case cover; in the portion corresponding to the cooling fan, the groove for guiding the cooling air is formed in the vehicle width direction of the case cover, wherein the groove is gradually along the rotation direction of the cooling fan No longer, and is characterized in that the deepest portion is formed to extend to the rear in the vehicle longitudinal direction than the center of the cooling fan.

  According to the present invention, a continuously variable transmission including a drive pulley, a driven pulley, and a belt is housed in a housing space formed by a transmission case and a case cover, and is provided on the case cover side of the drive pulley. A groove for guiding cooling air is formed inside the case cover corresponding to the cooling fan. For this reason, the cooling air pressure-fed by the cooling fan flows smoothly in the groove, so that it flows smoothly without stagnation, and the pressure-feeding efficiency of the cooling air increases, thereby improving the cooling efficiency of the continuously variable transmission. be able to.

  In addition, when a groove that guides cooling air is formed at a position corresponding to the cooling fan inside the case cover, a gap that extends in the radial direction of the cooling fan is provided between the case cover and the cooling fan. As compared with the case, the case cover does not expand in the radial direction of the cooling fan, so the case cover can be reduced in size.

1 is a left side view showing a scooter type motorcycle to which an embodiment of a cooling structure for a continuously variable transmission according to the present invention is applied. The left view which shows the power unit of FIG. The horizontal sectional view which shows the transmission device of the power unit of FIG. FIG. 4 is a perspective view showing the case cover of FIGS. 2 and 3 as viewed from the inside. Explanatory drawing explaining the flow condition of the cooling air in the transmission of FIG. FIG. 6 is a partially enlarged view showing a part (drive pulley side) of FIG. 5 in an enlarged manner. Explanatory drawing explaining the flow condition of the cooling air around the cooling fan in the conventional transmission.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a left side view showing a scooter type motorcycle to which an embodiment of a cooling structure for a continuously variable transmission according to the present invention is applied. 2 is a left side view showing the power unit of FIG. 1, and FIG. 3 is a horizontal sectional view showing a transmission device of the power unit of FIG. In the present embodiment, front / rear, left / right, and upper / lower expressions are based on an occupant at the time of boarding the vehicle.

  The scooter type motorcycle 1 includes an underbone type body frame 2. The vehicle body frame 2 is configured such that an under frame 4 extends downward from a head pipe 3 on the front head, and a seat rail 5 extends rearward and obliquely upward from a vehicle lower portion of the under frame 4. A front fork 6 is supported on the head pipe 3 so as to be rotatable left and right together with a handle bar 7, and a front wheel 8 is pivotally supported at the front end of the front fork 6. On the other hand, a power unit 10 is pivotally supported at the lower center of the body frame 2 via a swing bracket 9 so as to be swingable in the vertical direction around the pivot shaft 11.

  The power unit 10 is generally used for a scooter as shown in FIGS. 1 and 2, and the engine 12 and the transmission device 13 are integrally formed, and the rear wheel 14 is directly supported on the rear portion of the transmission device 13. Is done. A rear cushion unit (not shown) is stretched between the rear portion of the transmission device 13 and the rear portion (seat rail 5) of the vehicle body frame 2, and the power unit 10 and the rear wheel 14 are buffered and suspended by the rear cushion unit.

  As shown in FIG. 2, the engine 12 is configured such that a cylinder assembly 16 protrudes from a front side of a crankcase 15 as an engine case so as to be inclined forward in a substantially horizontal direction. The cylinder assembly 16 includes a cylinder block 17, a cylinder head 18, and a head cover 19 that are sequentially joined from the crankcase 15 side. Due to the combustion of the air-fuel mixture, the piston (not shown) reciprocates within the cylinder block 17, and the reciprocating motion causes the crankshaft 20 (FIG. 3) to rotate within the crankcase 15.

  As shown in FIG. 1, a seating seat 21 is placed on the body frame 2 above the seat rail 5 so as to be openable and closable, and an article storage box 22 capable of storing a helmet or the like is provided below the seating seat 21. . For this reason, by opening the seating sheet 21, articles can be taken into and out of the article storage box 22. The vehicle body frame 2 is entirely covered with a synthetic resin frame cover 23 to improve the appearance and protect internal devices. Moreover, the code | symbol 24 in FIG. 1 shows an air cleaner.

  As shown in FIG. 3, the transmission device 13 includes a continuously variable transmission 25 using a V-belt 37, a centrifugal clutch 26, and a transmission mechanism 27, shifting the driving force of the engine 12 to the rear wheel 14. introduce. A transmission case 28 as a case main body is integrally connected from one side (left side) of the crankcase 15 of the engine 12 and extends rearward of the vehicle. A case cover 29 covers an opening of the transmission case 28. The continuously variable transmission 25, the centrifugal clutch 26, and the transmission mechanism 27 are accommodated in a case space 30 as an accommodating space surrounded by the transmission case 28 and the case cover 29.

  The continuously variable transmission 25 is connected to the crankshaft 20 of the engine 12 so as to be integrally rotated, and is connected to a drive pulley 35 that is rotationally driven by the crankshaft 20 and a sleeve 32 that is rotatable relative to the driven shaft 31. And a V pulley 37 that is wound around the drive pulley 35 and the driven pulley 36 and transmits the rotational force (power) of the drive pulley 35 to the driven pulley 36.

  In the drive pulley 35, a fixed face 35A and a movable face 35B are arranged to face each other, and in the driven pulley 36, a fixed face 36A and a movable face 36B are arranged to face each other. A V-belt 37 is disposed between the fixed face 35A and the movable face 35B of the drive pulley 35 and between the fixed face 36A and the movable face 36B of the driven pulley 36. A spring 34 is interposed between the movable face 36B of the driven pulley 36 and a base plate 39 (described later) of the centrifugal clutch 26, and the movable face 36B is constantly urged toward the fixed face 36A.

  In the drive pulley 35, the centrifugal force acting on the weight roller 33 changes according to the rotation speed of the engine 12 (that is, the rotation speed of the crankshaft 20). Move radially outward. As a result, the movable face 35B moves in the axial direction of the crankshaft 20 and approaches the fixed face 35A, and the belt winding radius of the drive pulley 35 increases. At this time, the driven pulley 36 moves away from the fixed face 36A by moving the movable face 36B on the sleeve 32 against the biasing force of the spring 34 in the axial direction of the sleeve 32 (that is, the axial direction of the driven shaft 31). The belt winding radius of the driven pulley 36 is reduced. In this way, the rotation of the crankshaft 20 is steplessly changed (for example, increased in speed), and the sleeve 32 is rotated.

  The centrifugal clutch 26 is disposed between the driven pulley 36 and the driven shaft 31, and transmits the rotational force of the driven pulley 36, that is, the rotational force (power) of the sleeve 32, to the driven shaft 31 when turned on, and transmits it when turned off. Is released (disconnected). The centrifugal clutch 26 is disposed on the driven shaft 31 adjacent to the movable face 36B of the driven pulley 36, and includes a clutch housing 38, a base plate 39, and a clutch shoe 40.

  The clutch housing 38 is formed by integrating a side wall 41 extending in the radial direction with a flange 42 extending in the axial direction, and the side wall 41 is rotatably attached to the driven shaft 31 and formed in a cup shape as a whole. Is done. The base plate 39 is fixed to the end of the sleeve 32, and the clutch shoe 40 is pivotally supported on the sleeve 32. The clutch shoe 40 is slidably provided on the inner surface of the flange portion 42 in the clutch housing 38.

  Therefore, the rotational force transmitted to the driven pulley 36 and rotating the sleeve 32 rotates the base plate 39, and the clutch shoe 40 is brought into sliding contact with the inner surface of the flange portion 42 of the clutch housing 38 by the action of centrifugal force. As a result, the clutch housing 38 rotates integrally with the driven pulley 36, and the rotation of the driven pulley 36 is transmitted to the driven shaft 31. The rotational force transmitted to the driven shaft 31 is transmitted to the rear wheel 14 via the mission mechanism 27.

  The mission mechanism 27 decelerates the rotational force of the driven shaft 31 by the gear train (first mission gear 27A, second mission gear 27B, third mission gear 27C, fourth mission gear 27D) and transmits it to the output shaft 43. The first mission gear 27 </ b> A is formed at a position opposite to the centrifugal clutch 26 on the driven shaft 31. The second mission gear 27B is provided to rotate integrally with the intermediate shaft 44 and meshes with the first mission gear 27A. The third mission gear 27C is formed on the intermediate shaft 44. The fourth mission gear 27D is rotatably integrated with the output shaft 43 and meshes with the third mission gear 27C. By this transmission mechanism 27, the rotational force of the driven shaft 31 is reduced to a desired reduction ratio and transmitted to the output shaft 43, and the rear wheel 14 coupled to the output shaft 43 is integrally driven.

  The transmission mechanism 27 is liquid-tightly isolated in a transmission cover 45 provided in the transmission case 28 and immersed in oil. 3 denotes a kick starter shaft, and a kick starter mechanism 47 is operated by operating a kick starter lever (not shown) provided at the tip, and the crank shaft 20 is manually moved when the engine 12 is started. Rotate.

  Incidentally, as shown in FIGS. 3 and 5, a cooling fan (sirocco fan in the present embodiment) 51 is provided integrally on the case cover 29 side of the fixed face 35 </ b> A of the drive pulley 35. As shown in FIGS. 3 and 4, the case cover 29 is provided with an introduction duct 52 on the drive pulley 35 side (cooling fan 51 side) and a discharge duct at an intermediate position between the drive pulley 35 and the driven pulley 36. 53 is formed. The introduction duct 52 communicates with the case space 30 through an introduction opening 54 formed in the case cover 29. Further, the discharge duct 53 communicates with the case space 30 through a discharge port 55 of the discharge duct 53, and communicates with the atmosphere through a discharge port 56 (FIG. 2) of the discharge duct 53.

  Here, in the case space 30, frictional heat is generated by sliding contact between the V belt 37, the drive pulley 35, and the driven pulley 36 in the continuously variable transmission 25. Furthermore, frictional heat is also generated by sliding contact between the clutch housing 38 of the centrifugal clutch 26 and the clutch shoe 40.

As shown in FIG. 5, by the rotation of the cooling fan 51, the outside air A from the introduction duct 52 is introduced as cooling air B into the case space 30 through the introduction opening 54 (FIG. 4). The cooling air B flows in the case space 30 from the drive pulley 35 side to the driven pulley 36 side as indicated by an arrow C by the pneumatic supply of the rotating cooling fan 51, and is exhausted from the discharge port 55 of the discharge duct 53. It becomes D and flows into the exhaust duct 53, and is exhausted from the exhaust port 56 (FIG. 2) of the exhaust duct 53 to the atmosphere. While the cooling air B flows in the case space 30, both the frictional heats described above are dissipated, and the continuously variable transmission 25 and the centrifugal clutch 26 are cooled.

  In the present embodiment, as shown in FIGS. 3, 4, and 6, the introduction groove 60 is formed along the outer peripheral edge 58 of the cooling fan 51 on the front end surface 57 corresponding to the cooling fan 51 inside the case cover 29. Has been. The introduction groove 60 is formed in a slope shape in which the groove depth gradually increases along the rotation direction P of the cooling fan 51. Furthermore, the introduction groove 60 is formed so as to extend to the position where the deepest portion 61 is located behind the center of the cooling fan 51 (that is, the crankshaft 20) in the vehicle longitudinal direction.

  The introduction groove 60 as described above is formed in the front end surface 57 inside the case cover 29, so that the space volume between the front end surface 57 of the case cover 29 and the outer peripheral edge 58 of the cooling fan 51 can be reduced. Along the rotational direction P of 51, the case cover 29 gradually expands in the depth direction (vehicle width direction). For this reason, the cooling air B pumped by the rotating cooling fan 51 flows smoothly without staying in the introduction groove 60 and flows in the case space 30 from the drive pulley 35 side to the driven pulley 36 side at a high speed. As a result, the pumping efficiency of the cooling air B increases.

With the configuration as described above, according to the present embodiment, the following effects (1) and (2) are obtained.
(1) As shown in FIGS. 5 and 6, a case space 30 in which a continuously variable transmission 25 including a drive pulley 35, a driven pulley 36, and a V-belt 37 is formed by a transmission case 28 and a case cover 29. The introduction groove 60 that guides the cooling air B to the inner front end surface 57 of the case cover 29 corresponding to the outer peripheral edge 58 of the cooling fan 51 provided on the case cover 29 side of the drive pulley 35 is cooled. It is formed so as to gradually become deeper along the rotation direction P of the fan 51. For this reason, the cooling air B pumped by the cooling fan 51 flows in the introduction groove 60 and flows smoothly without stagnation, and the pumping efficiency of the cooling air B increases, and the continuously variable transmission 25. In addition, the cooling efficiency of the centrifugal clutch 26 can be improved.

  (2) Since the introduction groove 60 that guides the cooling air B is formed in the front end surface 57 corresponding to the cooling fan 51 inside the case cover 29 in the depth direction of the case cover 29, the case cover 29 and the cooling fan The case cover 29 does not expand in the radial direction of the cooling fan 51, compared to a case where a gap that extends in the radial direction of the cooling fan 51 is provided between the case cover 29 and the cooling fan 51. As a result, the case cover 29 can be downsized, the case cover 29 can be made highly rigid, and the cost of the power unit 10 can be reduced. In addition, since the case cover 29 is downsized, the degree of freedom in layout of the oil filter 62 (FIG. 2), the oil strainer, and the like can be improved.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention.

12 Engine 15 Crankcase (Engine case)
20 Crankshaft 25 Continuously variable transmission 28 Transmission case 29 Case cover 30 Case space (accommodating space)
31 Drive shaft 35 Drive pulley 36 Driven pulley 37 V belt 51 Cooling fan 57 Front end surface 58 Outer peripheral edge 60 Introduction groove 61 Deepest part B Cooling air P Rotating direction

Claims (2)

A continuously variable transmission that transmits the power of a drive pulley driven by a crankshaft of an engine provided in a vehicle to a driven pulley that is arranged to be relatively rotatable with respect to a driven shaft through a belt,
By covering the transmission case extending from the engine case with the case cover, an accommodation space for accommodating the continuously variable transmission is formed,
A cooling fan is provided on the case cover side of the drive pulley, and cooling of the continuously variable transmission that cools the continuously variable transmission by introducing and flowing cooling air into the accommodation space by the rotation of the cooling fan. Structure,
A groove for guiding the cooling air is formed in a position corresponding to the cooling fan inside the case cover in a vehicle width direction of the case cover .
The cooling structure for a continuously variable transmission , wherein the groove is gradually deepened along the rotation direction of the cooling fan, and the deepest portion extends from the center of the cooling fan to the rear in the vehicle front-rear direction. . The cooling structure for a continuously variable transmission according to claim 1, wherein the groove is formed inside the case cover along the outer peripheral edge of the cooling fan.

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