JP5854273B2 - Gear case lubrication structure - Google Patents

Description

  The present invention provides a gear case in which an input gear shaft to which power from a crankshaft is transmitted, an intermediate gear shaft having an axis parallel to the input gear shaft, and an output gear shaft are rotatably supported. A gear speed reduction mechanism that constitutes a power transmission path from the input gear that receives the rotational power from the shaft and rotates around the central axis of the input gear shaft to the output gear shaft through the intermediate gear shaft is housed and oil is contained. The gear case is stored in the gear case so as to rotate around a center axis of a specific gear shaft that is one of the input gear shaft, the intermediate gear shaft, and the output gear shaft. An oil receiving portion that receives oil splashed by a gear that constitutes the portion, and oil from the oil receiving portion among the input gear shaft, the intermediate gear shaft, and the output gear shaft. Relates to a lubricating structure of the gear case and the oil supply means is provided for guiding the the gear shaft side except gear shaft.

  A part of the driven gear provided on the output gear shaft is immersed in oil, and the oil is splashed to the lubricated portion of the input gear shaft and the intermediate gear shaft other than the output gear shaft by the rotation of the driven gear. The one that is hung is known from Patent Document 1.

JP-A-11-218213

  However, in the one disclosed in Patent Document 1, oil is output from the gear of the output gear shaft that is the end in the side view from the axial direction of the gear shaft among the input gear shaft, the intermediate gear shaft, and the output gear shaft. Since the oil is splashed up, it becomes difficult to make the oil reach the oil supply passage of the intermediate gear shaft located far from the output gear shaft by splashing.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gear case lubrication structure in which oil can easily reach all gear shafts of a gear reduction mechanism.

In order to achieve the above object, according to the present invention, an input gear shaft to which power from a crankshaft is transmitted, and an intermediate gear shaft and an output gear shaft having axes parallel to the input gear shaft are rotatably supported. A gear reduction that constitutes a power transmission path from the input gear that receives the rotational power from the input gear shaft and rotates around the central axis of the input gear shaft to the output gear shaft through the intermediate gear shaft. A mechanism is accommodated and oil is stored, and the gear case rotates around a central axis of a specific gear shaft that is one of the input gear shaft, the intermediate gear shaft, and the output gear shaft. An oil receiving portion that receives oil splashed by a gear that constitutes a part of the gear reduction mechanism, and oil from the oil receiving portion, the input gear shaft, the intermediate gear shaft, and In a lubricating structure of a gear case provided with an oil supply means that leads to a gear shaft side other than the specific gear shaft among the output gear shafts, the intermediate gear shaft that is the specific gear shaft is the input gear in a side view. Of the plurality of gears that are arranged between the shaft and the output gear shaft and that constitute the gear reduction mechanism, the lower end of the intermediate gear provided on the intermediate gear shaft jumps up the oil so that the remaining of the gear reduction mechanism The oil receiving portion is disposed lower than the lower end of the gear in a side view, and the oil receiving portion is higher than the input gear shaft, the intermediate gear shaft, and the output gear shaft in a side view and the input gear shaft and the output gear shaft. is disposed between, the oil receiving portion, said extends along the central axis of the intermediate gear shaft is formed in a gutter shape having a cross section that is open upward, before constitutes a part of the oil supply means An oil guide wall provided in the gear case receives oil overflowing from the oil receiving portion and guides it to the output gear shaft so that it crosses the oil receiving portion in a plan view and is below the oil receiving portion. It placed a first aspect the Rukoto.

In the present invention, in addition to the configuration of the first feature, the upper end portion of the oil guide wall is located above the oil receiving portion at a portion located on the input gear shaft side from the oil receiving portion in a side view. The second feature is that a projecting portion projecting is formed.

Further, the present invention provides a gear case in which an input gear shaft to which power from a crankshaft is transmitted, an intermediate gear shaft having an axis parallel to the input gear shaft, and an output gear shaft are rotatably supported. A gear reduction mechanism that houses a power transmission path from the input gear that receives the rotational power from the input gear shaft and rotates around the central axis of the input gear shaft to the output gear shaft through the intermediate gear shaft is housed. The gear reduction mechanism is configured such that oil is stored and the gear case rotates around a central axis of a specific gear shaft that is one of the input gear shaft, the intermediate gear shaft, and the output gear shaft. An oil receiving portion that receives oil splashed by a gear that forms a part of the oil receiving portion, and oil from the oil receiving portion among the input gear shaft, the intermediate gear shaft, and the output gear shaft. In a lubricating structure of a gear case provided with an oil supply means that leads to a gear shaft side other than the specific gear shaft, the intermediate gear shaft that is the specific gear shaft has the input gear shaft and the output gear shaft in a side view. Among the plurality of gears constituting the gear reduction mechanism, the lower end of the intermediate gear provided on the intermediate gear shaft jumps up the oil, and the lower end of the remaining gears of the gear reduction mechanism. The oil receiving portion is disposed at a lower position in a side view, and is disposed above the input gear shaft, the intermediate gear shaft and the output gear shaft in a side view and between the input gear shaft and the output gear shaft, A gear case houses a belt-type continuously variable transmission provided between one end of the crankshaft and the input gear shaft that is rotatably supported by an engine crankcase. A transmission case connected to the link case, a wet type first housing that is connected in series to the belt-type continuously variable transmission and accommodates at least a part of the mechanical transmission provided on the input gear shaft and the gear reduction mechanism. A gear cover formed between the transmission case and a transmission chamber, and a transmission clutch for switching a gear stage of the mechanical transmission according to the rotational speed of the input gear shaft; A second housing chamber that is housed and partitioned from the first transmission chamber is formed between the gear cover and a clutch cover that is coupled to the gear cover, and the oil receiving portion is formed by the gear case. An oil supply passage that is formed on the upper wall of the portion that forms the first transmission chamber so as to overlap the intermediate gear shaft in plan view and that constitutes part of the oil supply means and guides oil to the input gear shaft. The gear cover and A third feature is that a notch for dropping oil toward the lower intermediate gear shaft side is provided in the connection portion of the oil receiving portion and the oil supply passage formed in the clutch cover.

According to the present invention, in addition to the configuration of the first feature, the gear case is a belt-type continuously variable provided between the crankshaft rotatably supported by the crankcase of the engine and one end of the input gear shaft. A transmission case that houses a transmission and is connected to the crankcase; at least a part of a mechanical transmission that is connected in series to the belt-type continuously variable transmission and provided on the input gear shaft; and the gear A gear cover that is formed between the transmission case and a wet first transmission chamber that houses a speed reduction mechanism is coupled to the transmission case, and the mechanical transmission according to the rotational speed of the input gear shaft A clutch cover that is coupled to the gear cover by forming a second storage chamber that is separated from the first shift chamber and that is separated from the first shift chamber. Oh A gear receiving portion is formed on an upper wall of a portion of the gear case forming the first transmission chamber so as to overlap the intermediate gear shaft in plan view, and constitutes a part of the oil supply means to form the input gear An oil supply path for guiding oil to the shaft is formed in the gear cover and the clutch cover, and a notch for dropping the oil toward the lower intermediate gear shaft side is provided in the connection portion of the oil receiving part and the oil supply path. This is the fourth feature.

According to the present invention, in addition to the configuration of the fourth feature, the upper end portion of the oil guide wall is located above the oil receiving portion at a portion located on the input gear shaft side from the oil receiving portion in a side view. A fifth feature is that a projecting portion projecting is formed.

According to the present invention, in addition to the configurations of the third to fifth features, the other end portion of the input gear shaft that coaxially has an oil hole for guiding oil to the wet-type transmission clutch and the mechanical transmission, The oil receiving portion and the oil hole are communicated with each other via a bearing having a seal, which is rotatably supported by a first bearing portion provided on the clutch cover via a bearing with a seal. The sixth feature.

Furthermore, in addition to the configurations of the third to sixth features, the present invention can freely rotate the other end portion of the intermediate gear shaft whose one end portion is supported on a second bearing portion provided in the case main body on the gear cover. A third bearing portion that is supported on the shaft, a return passage that is axially displaced from the intermediate gear so as to return oil from the second transmission chamber to the first transmission chamber, and is disposed below the third bearing portion; A seventh feature is that a reinforcing rib connecting the bottom wall of the gear cover and the third bearing portion is provided opposite to the opening end of the return passage toward the first transmission chamber.

Furthermore, the present invention provides a gear case in which an input gear shaft to which power from a crankshaft is transmitted, an intermediate gear shaft having an axis parallel to the input gear shaft, and an output gear shaft are rotatably supported. A gear reduction mechanism that constitutes a power transmission path from the input gear that receives the rotational power from the gear shaft and rotates about the central axis of the input gear shaft to the output gear shaft through the intermediate gear shaft is accommodated and oil And the gear case rotates around a central axis of a specific gear shaft that is one of the input gear shaft, the intermediate gear shaft, and the output gear shaft. An oil receiving portion that receives oil splashed by a gear that constitutes a part, and oil from the oil receiving portion among the input gear shaft, the intermediate gear shaft, and the output gear shaft In a lubricating structure of a gear case provided with an oil supply means that leads to a gear shaft side other than the specific gear shaft, the intermediate gear shaft that is the specific gear shaft has the input gear shaft and the output gear shaft in a side view. Among the plurality of gears constituting the gear reduction mechanism, the lower end of the intermediate gear provided on the intermediate gear shaft jumps up the oil, and the lower end of the remaining gears of the gear reduction mechanism. The oil receiving portion is disposed at a lower position in a side view, and is disposed above the input gear shaft, the intermediate gear shaft and the output gear shaft in a side view and between the input gear shaft and the output gear shaft, According to an eighth feature of the present invention, the oil supply means guides oil from the oil receiving portion to the input gear shaft and the output gear shaft.

Furthermore, in addition to the configuration of the eighth feature, the ninth feature of the present invention is that the oil receiving portion is provided at a position overlapping the intermediate gear shaft in plan view.

  Further, in the present invention, in addition to the configuration of the eighth or ninth feature, the oil receiving portion is formed in a bowl shape having a transverse section opened upward, and constitutes a part of the oil supply means to form the gear case. A tenth feature is that the oil guide wall provided in is arranged so as to cross the lower portion of the oil receiving portion in a plan view.

According to the present invention, in addition to the configurations of the first to tenth features, the lower part of the gear case is formed with a concave portion recessed downward so that the lower part of the intermediate gear shaft is lowest. Eleven features.

In the present invention, in addition to the configurations of the first to eleventh features, the central axis of the intermediate gear shaft is disposed lower than the central axis of the input gear shaft and the central axis of the output gear shaft in a side view. This is the twelfth feature.

  The transmission shaft 14 of the embodiment corresponds to the input gear shaft of the present invention, and the axle 15 of the embodiment corresponds to the output gear shaft of the present invention.

  According to the first feature of the present invention, the intermediate gear shaft is disposed between the input gear shaft and the output gear shaft in a side view, and the intermediate gear provided on the intermediate gear shaft splashes oil. The oil can be easily distributed around the input gear shaft and the output gear shaft arranged on both sides of the intermediate gear shaft in a side view. An oil receiving portion for receiving the splashed oil is disposed above the input gear shaft, the intermediate gear shaft and the output gear shaft and between the input gear shaft and the output gear shaft in a side view, and the oil receiving portion receives oil from the oil receiving portion. The oil supply means guides the input gear shaft and the output gear shaft to the input gear shaft and the output gear shaft, so that stable oil distribution and supply can be performed on the input gear shaft and the output gear shaft, and the oil receiver having a bowl-shaped cross section opened upward. The oil guide wall that extends along the central axis of the intermediate gear shaft and receives oil overflowing from the oil receiving portion and guides it to the output gear shaft is below the oil receiving portion while crossing the oil receiving portion in plan view. Therefore, it is possible to increase the collection efficiency of the oil overflowing from the oil receiving portion at the oil guide wall and supply a sufficient amount of oil to the output gear shaft side.

  According to the second and fifth features of the present invention, the protruding portion formed at the upper end portion of the oil guide wall protrudes above the oil receiving portion on the input gear shaft side from the oil receiving portion in a side view. Therefore, the collection efficiency of the oil overflowing from the oil receiving portion to the oil guide wall can be further increased.

The first of the present invention 3, according to a fourth aspect, the first wet housing at least partially and gear reduction mechanism of the mechanical transmission between the transmission case for housing a belt continuously variable transmission A transmission chamber is formed between the transmission case and the gear cover, and an oil receiving portion is formed on the upper wall of a portion of the gear case forming the first transmission chamber so as to overlap the intermediate gear shaft in plan view. A part of the oil supply means is formed in the clutch cover and the gear cover which are coupled to the gear cover by forming a second storage chamber which is separated from the first transmission chamber by accommodating the clutch and the gear cover. An oil supply path that guides oil to the input gear shaft is formed, and a notch that drops oil toward the intermediate gear shaft side is provided in the oil receiving section and the connection section of the oil supply path, so the oil from the oil receiving section is input. When it leads to the gear shaft side Monitor can also be guided to the intermediate gear shaft, while lubricating the input gear shaft can be lubricated even intermediate gear shaft with a simple structure.

According to a sixth aspect of the present invention, the other end portion of the input gear shaft having an oil hole coaxially is rotatably supported by a seal-bearing first bearing portion of the clutch cover, formed in a cylindrical shape Since the oil receiving portion and the oil hole communicate with each other through the oil supply passage, the oil from the oil supply passage is prevented from being applied to the outside of the wet transmission clutch, thereby contributing to reduction of rotational friction of the transmission clutch. be able to.

According to a seventh aspect of the present invention, the side wall portions return passage returns oil from the second control chamber to the first speed-change chamber, interposed between the first of the gear cover 1 and the second control chamber, the third Since the opening is made in the portion surrounded by the bearing portion, the reinforcing rib and the bottom wall of the gear cover, the effect of the rotation of the intermediate gear despite the fact that the oil in the lower part of the first transmission chamber is repelled by the intermediate gear Can be prevented from reaching the return passage, the backflow of oil from the return passage to the second shift chamber side can be prevented, and the friction due to the shift clutch can be further reduced by placing the second shift chamber in a dry environment.

Further, according to the eleventh feature of the present invention, the concave portion recessed downward so as to make the lower portion of the intermediate gear shaft the lowest is formed in the lower portion of the gear case, thereby reducing the amount of oil necessary for lubrication. In addition, it is possible to reduce friction due to oil agitation in the gear reduction mechanism, which can contribute to improvement of power transmission efficiency.

According to the twelfth feature of the present invention, since the center axis of the intermediate gear shaft is lower in side view than the center axes of the input gear shaft and the output gear shaft, the intermediate gear can be brought closer to the bottom of the gear case. This facilitates the reduction of the size of the intermediate gear. In addition, the input gear shaft and the output gear shaft can be arranged close to the intermediate gear shaft, and the oil can be guided to the input gear shaft and the output gear shaft more efficiently. It can be configured compactly.

It is a partially cutaway top view of a power unit. It is a principal part enlarged view of FIG. FIG. 3 is an enlarged view taken along arrow 3 in FIG. 1. FIG. 4 is a cross-sectional view of the gear case taken along line 4-4 of FIG. FIG. 5 is a cross-sectional view of the gear case taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 of FIG.

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

  First, in FIG. 1, the power unit P is mounted on, for example, a motorcycle, and includes an engine E and a power transmission device T that transmits power from the engine E to a rear wheel (not shown). The power transmission device T includes a belt-type continuously variable transmission 13 that continuously changes the rotational power of a crankshaft 12 rotatably supported by a crankcase 11 of an engine E, a transmission shaft 14, and the belt-type continuously variable. A starting clutch 17 interposed between the transmissions 13, a mechanical transmission 18 connected to the belt-type continuously variable transmission 13 in series and provided on the transmission shaft 14, and the rotational speed of the transmission shaft 14. Accordingly, a shift clutch 19 for switching the gear position of the mechanical transmission 18 and a gear reduction mechanism 20 provided between the mechanical transmission 18 and the axle 15 of the rear wheel are provided.

  The belt-type continuously variable transmission 13 is accommodated in a transmission case 21 that is connected to the crankcase 11 and extends rearward. The transmission case 21 is integrally connected to the crankcase 11. A case main body 22 extending rearward and a transmission cover 23 coupled to the case main body 22 so as to cover the case main body 22 from the outside.

  The belt type continuously variable transmission 13 includes a drive pulley 24 provided on the crankshaft 12, a driven pulley 25 provided on the transmission shaft 14, and an endless V-belt wound around the drive pulley 24 and the driven pulley 25. 26, the drive pulley 24 is provided at one end of the crankshaft 12 that enters the transmission case 21, and the driven pulley 25 has the axis parallel to the crankshaft 12. Is provided.

  The drive pulley 24 includes a fixed pulley half 27 fixed to the crankshaft 12 and a movable pulley half 28 that can be moved toward and away from the fixed pulley half 27. Driven in the axial direction by a centrifugal force acting on a weight roller 30 disposed between the ramp plate 29 fixed to the shaft 12 and the movable pulley half 28.

  Referring also to FIG. 2, the driven pulley 25 is fixed to a cylindrical inner cylinder 33 that is rotatably supported on the transmission shaft 14 while coaxially surrounding the transmission shaft 14. 31 and the outer cylinder 34 that coaxially surrounds the inner cylinder 33 so as to be capable of axial relative movement and relative rotation with respect to the inner cylinder 33, thereby enabling proximity and separation to the fixed pulley half 31. The V-belt 26 is wound around the fixed pulley half 31 and the movable pulley half 32. A torque cam mechanism 35 that applies a component force in the axial direction between the pulley halves 31 and 32 in accordance with the relative rotational phase difference between the movable pulley half 32 and the fixed pulley half 31 includes the inner cylinder 33 and the outer pulley 33. The movable pulley half 32 provided between the cylinders 34 is elastically biased toward the fixed pulley half 31 by the coil spring 36.

  The starting clutch 17 is provided between one end of the transmission shaft 14 and the inner cylinder 33 so as to be in a power transmission state as the engine speed exceeds a set starting speed. A hook-like clutch outer 37 fixed to one end of the transmission shaft 14, a drive plate 38 fixed to the inner cylinder 33, and centrifugal weights 39 pivotally supported at a plurality of locations of the drive plate 38; Each centrifugal weight 39 is provided with a clutch spring 40 provided between the drive plates 38, and the centrifugal force acting on each centrifugal weight 39 according to the rotation of the drive plate 38 is a spring biasing force of each clutch spring 40. The centrifugal weights 39 are frictionally engaged with the inner periphery of the clutch outer 37 when the upper cylinder exceeds the inner cylinder 33, that is, the fixed pulley half 31 and the clutch. Chiauta 37 that is, that the transmission shaft 14 is coupled.

  3 to 5, the mechanical transmission 18, the transmission clutch 19, and the gear reduction mechanism 20 are accommodated in a gear case 43, and the gear case 43 includes the mechanical case. A gear that is formed between the case main body 22 of the transmission case 21 and is connected to the case main body 22 by forming a wet first transmission chamber 46 that houses at least a part of the transmission 18 and the gear reduction mechanism 20. A clutch cover 45 that is coupled to the gear cover 44 by forming a cover 44 and a second shift chamber 47 that accommodates the shift clutch 19 and is partitioned from the first shift chamber 46. It consists of.

  At the rear of the case main body 22 in the transmission case 21, a transmission chamber forming wall 22 a that forms a recess 48 that faces the opposite side of the belt-type continuously variable transmission 13 and is connected endlessly is formed in the first transmission chamber 46. The gear cover 44 is fastened to the transmission chamber forming wall side wall 22a with a plurality of bolts 49, 49... So as to close the opening end of the recess 48. Further, a recess 50 facing the opposite side of the belt-type continuously variable transmission 13 is formed in the front portion of the gear cover 44, and a transmission chamber forming wall 44a that is endlessly connected serves as a peripheral wall of the second transmission chamber 47. The clutch cover 45 is fastened to the transmission chamber forming wall 44a with a plurality of bolts 51, 51... So as to close the open end of the recess 50.

  An intermediate portion of the transmission shaft 14 rotatably passes through cylindrical support cylinder portions 22b and 44b provided in the case main body 22 and the gear cover 44 of the transmission case 21, and the support cylinder portion 22b and the Between the transmission shafts 14, a ball bearing 52 and an annular seal member 53 are interposed in order from the first transmission chamber 46 side, and the other end portion of the transmission shaft 14 is a cylindrical shape provided on the clutch cover 45. The first bearing portion 45a is rotatably supported through a bearing 54 with a seal. That is, the transmission shaft 14 is rotatably supported by the gear case 43.

  The mechanical transmission 18 includes a planetary gear mechanism 55 and a one-way clutch 56 that regulates the rotational direction of the sun gear 58 in the planetary gear mechanism 55, and constitutes a part of the mechanical transmission 18. The planetary gear mechanism 55 is accommodated in the first transmission chamber 46, and the one-way clutch 56 is accommodated in the second transmission chamber 47 together with the transmission clutch 19.

  The planetary gear mechanism 55 includes a ring gear 57 that is fixed to the transmission shaft 14, a sun gear 58 that can rotate relative to the transmission shaft 14, and a plurality of gears that mesh with the ring gear 57 and the sun gear 58. Are provided with planetary gears 59, 59... And a planet carrier 60 that rotatably holds the planetary gears 59, 59. The sun gear 58 is fixed to one end of a transmission cylinder shaft 61 that relatively rotatably surrounds the transmission shaft 14, and the transmission cylinder shaft 61 has a cylindrical support cylinder portion 44 b provided on the gear cover 44. It penetrates freely. Thus, a plurality of needle bearings 62 are interposed between the transmission cylinder shaft 61 and the transmission shaft 14, and a ball bearing 63 is interposed between the support cylinder portion 44 b and the transmission cylinder shaft 61. The planet carrier 60 is fixed to an input gear 70 that constitutes a part of the gear reduction mechanism 20 and surrounds the transmission cylindrical shaft 61, and a needle is interposed between the input gear 70 and the transmission cylindrical shaft 61. A bearing 64 is interposed.

  The transmission clutch 19 has the transmission shaft in a state where the speed ratio of the belt-type continuously variable transmission 13 is low after the start clutch 17 enters a power transmission state as the engine speed exceeds the start speed. 14 is provided between the other end portion of the transmission shaft 14 and the other end portion of the transmission cylinder shaft 61 so as to be in a power transmission state in response to the rotation number 14 exceeding the set rotation number. A hook-like clutch outer 65 fixed to the other end of the cylindrical shaft 61, a drive plate 66 fixed to the other end of the transmission shaft 14, and centrifugal weights pivotally supported at a plurality of locations of the drive plate 66 67, and centrifugal weights 67, and clutch springs (not shown) provided between the drive plates 66, and act on the centrifugal weights 67 according to the rotation of the drive plates 66. When the core force exceeds the spring biasing force of each clutch spring (not shown), the centrifugal weights 67 are frictionally engaged with the inner periphery of the clutch outer 65, so that the transmission shaft 14, the clutch outer 65, that is, the transmission cylinder shaft. 61 will be combined.

  The one-way clutch 56 regulates the rotation direction of the clutch outer 65, the transmission cylinder shaft 61 and the sun gear 58 in the same direction as the transmission shaft 14, and the second transmission chamber 47 of the gear cover 44. A ratchet gear 68 fixed to the wall faced to the front and a plurality of pawl members 69 that can be engaged with the inner periphery of the ratchet gear 68 and are pivotally supported by the clutch outer 65 of the transmission clutch 19. , 69...

  Thus, when the starting clutch 17 is in a power transmission state and the transmission shaft 14 rotates, the planetary gear mechanism 55 rotates the ring gear 57 together with the transmission shaft 14, and a plurality of planetary gears that rotate according to the rotation of the ring gear 57. 59, 59..., The sun gear 58 is subjected to a force that rotates in the opposite direction to the transmission shaft 14 and the ring gear 57. When the speed change clutch 19 is in the disconnected state, the one-way clutch 56 works. Thus, the rotation of the clutch outer 65, the transmission cylinder shaft 61, and the sun gear 58 in the direction opposite to the transmission shaft 14 is restricted, and the sun gear 58 is held in a rotation stopped state. Therefore, the planetary gears 59, 59... Revolve around the sun gear 58 together with the planet carrier 60 and the input gear 70, and the input gear 70 transmits the transmission at a rotational speed that is, for example, ½ of the rotational speed of the transmission shaft 14. It rotates in the same direction as the shaft 14.

  When the rotational speed of the transmission shaft 14 increases and the transmission clutch 19 is in the connected state, the transmission shaft 14 and the clutch outer 65 rotate in the same direction at the same rotational speed. , 58, 59... Disappears, and the input gear 70 rotates in the same direction at the same speed as the transmission shaft 14.

  Rotational power from the crankshaft 12 is transmitted to the transmission shaft 14 via the belt-type continuously variable transmission 13 and the starting clutch 17, and the gear-type reduction mechanism 20 is an input gear shaft. The rotational power of the transmission shaft 14 is received via the planetary speed reduction mechanism 55 and the power from the input gear 70 rotating around the central axis of the transmission shaft 14 to the axle 15 which is the output gear shaft through the intermediate gear shaft 16. Configure the transmission path.

  Referring also to FIG. 6, the intermediate gear shaft 16 has an axis parallel to the transmission shaft 14 and is disposed between the transmission shaft 14 and the axle 15 in a side view. One end of the intermediate gear shaft 16 is rotatably supported via a ball bearing 74 on a cylindrical second bearing portion 22c provided on the case main body 22 in the case 43, and the other end of the intermediate gear shaft 16 is The gear case 43 is rotatably supported by a cylindrical third bearing portion 44 c provided on the gear cover 44 via a ball bearing 75.

  One end portion of the axle 15 is rotatably supported by a cylindrical fourth bearing portion 22 d provided on the case main body 22 in the gear case 43 via a ball bearing 76. The other end side of the axle 15 passes through a cylindrical support cylinder portion 44d provided at the rear portion of the gear cover 44 in the gear case 43 so as to be freely rotatable, and between the axle 15 and the support cylinder portion 44d. An annular seal member 76 and a ball bearing 77 arranged outside the seal member 76 are interposed.

  The intermediate gear shaft 16 is provided with first and second intermediate gears 71 and 72 having different outer diameters, and the intermediate gear is configured so that the large-diameter first intermediate gear 71 meshes with the input gear 70. The second intermediate gear 72 having a small diameter is fixed near the other end of the shaft 16 and is integrally formed near one end of the intermediate gear shaft 16. An output gear 73 that meshes with the second intermediate gear 72 is fixed to a portion near one end of the axle 15.

  In the gear case 43, oil is stored in the lower part of the first transmission chamber 46. The oil level becomes a level indicated by a straight line L1 in FIG. 5 when the motorcycle is stopped, and in FIG. The level is indicated by a straight line L2.

  Incidentally, the oil in the gear case 43 rotates around the central axis of any one of the transmission shaft 14, the intermediate gear shaft 16 and the axle 15 and forms a part of the gear reduction mechanism 20. In the present invention, the first and second intermediate gears 71 provided on the intermediate gear shaft 16 with different outer diameters among the plurality of gears 70 to 73 constituting the gear reduction mechanism 20 in the present invention. , 72, the lower end of the first intermediate gear 71 having the large diameter is the lower end of the input gear 70, the second intermediate gear 72, and the output gear 73 that are the remaining gears of the gear reduction mechanism 20 so that the oil jumps up. Rather than in a side view.

  Moreover, in the lower part of the gear case 43 forming the first transmission chamber 46, that is, in the lower part of the transmission chamber forming wall 22a and the gear cover 44 in the case main body 22, as shown in FIGS. A concave portion 78 that is recessed downward is formed so that the lower portion of the gear shaft 16 is lowest.

  4, the central axis C2 of the intermediate gear shaft 16 is disposed lower than the central axis C1 of the transmission shaft 14 and the central axis C3 of the axle 15 in a side view.

  In the gear case 43, an oil receiving portion 80 that receives the oil splashed by the first intermediate gear 71 that rotates in the first transmission chamber 46, and the oil from the oil receiving portion 80, the transmission shaft 14 and the oil An oil supply means 81 for guiding to the axle 15 side is provided.

  The oil receiving portion 80 is provided on the upper wall of the portion of the gear case 43 that forms the first transmission chamber 46 so as to extend along the central axis C2 of the intermediate gear shaft 16. In the embodiment, the transmission is formed on the upper wall of the transmission chamber forming wall 22 a and the upper wall of the gear cover 44 in the case main body 22 constituting a part of the transmission case 21. In addition, the oil receiving portion 80 is disposed at a position overlapping the intermediate gear shaft 16 in a plan view (in this embodiment, a position directly above the intermediate gear shaft 16), and is scattered from the upper portion of the first intermediate gear 71. It is formed in a bowl shape having a transverse cross section opened upward on the input gear 70 side so as to receive the incoming oil, and above the transmission shaft 14, the intermediate gear shaft 16 and the axle 15 and in the side view. It is disposed between the transmission shaft 14 and the axle 15.

  The oil supply means 81 includes an oil guide wall 82 that receives the oil overflowing from the oil receiving portion 80 and guides it to the axle 15 side, and an oil supply path 83 that guides the oil from the oil receiving portion 80 to the transmission shaft 14 side. It consists of.

  The oil guide wall 82 is integrally provided on the wall surface facing the first transmission chamber 46 in the case main body 22 of the transmission case 21 constituting a part of the gear case 43 so as to protrude from the wall surface, In plan view, it is disposed below the oil receiving portion 80 as shown in FIG. 4 while traversing the oil receiving portion 80 as shown in FIG.

  Moreover, the upper end portion of the oil guide wall 82 is disposed closer to the transmission shaft 14 than the oil receiving portion 80 in a side view, and the upper end portion of the oil guide wall 82 is provided with the oil receiving portion 80. In addition, a protruding portion 82a protruding upward is integrally formed.

  In addition, an arc-shaped receiving projection 84 opened upward is integrated with a lower end of a cylindrical fourth bearing portion 22d provided on the case main body 22 so as to rotatably support one end portion of the axle 15. The lower end of the oil guide wall 82 is connected to the receiving projection 84.

The oil supply passage 83 is linearly connected to the oil receiving portion 80, and a passage 85 provided in the transmission chamber forming wall 44a of the gear cover 44 and the clutch cover 45, and a first bearing portion 45a of the clutch cover 45. and so connecting the said passages 85 linearly formed in a cylindrical shape with a passage 86 provided in the front Symbol clutch cover 45. In addition, a connection portion between the oil receiving portion 80 and the passage 85 in the oil supply passage 83 is provided with a notch 87 for dropping oil toward the lower intermediate gear shaft 16 as shown in FIG. In this embodiment, the notch 87 is provided on the gear cover 44 side, but a notch may be provided on the case main body 22 side.

A bottomed oil hole 88 communicating with the oil supply passage 83 in the first bearing portion 45a is provided on the other end side of the transmission shaft 14 in order to guide oil to the transmission clutch 19 and the mechanical transmission 18 which are wet. Is provided coaxially, and an outer end of a communication hole 89 provided in the transmission shaft 14 so as to pass the inner end through the oil hole 88 is interposed between the transmission cylinder shaft 61 and the transmission shaft 14. An opening is formed between the needle bearings 62 and 62 on the outer surface of the transmission shaft 14. The outer end of the communication hole 91 provided in the transmission shaft 14 so as to pass the inner end through the oil hole 88 is a ball bearing 52 interposed between the support cylinder portion 22b of the case main body 22 and the transmission shaft 14. Further, an opening is formed between the seal member 53 and the outer surface of the transmission shaft 14.

  The first and second intermediate gears 71, 72 are axially directed to the transmission chamber forming wall 44 a of the gear cover 44 in the gear case 43 so that oil is returned from the second transmission chamber 47 to the first transmission chamber 46. As shown in FIG. 5, there is provided a return passage 90 disposed below the third bearing portion 44c, and a reinforcing rib 44e facing the opening end of the return passage 90 toward the first transmission chamber 46 is provided. The bottom wall of the gear cover 44 and the third bearing portion 44c are connected to each other so as to be integrated with the gear cover 44.

  Next, the operation of this embodiment will be described. In the gear reduction mechanism 20 accommodated in the first transmission chamber 46 of the gear case 43, the intermediate gear shaft 16 is a transmission shaft 14 that is an input gear shaft in a side view, and First and second intermediate gears 71 and 72 provided on the intermediate gear shaft 16 with different outer diameters among the plurality of gears 70 to 73 that are arranged between the axle shafts 15 that are output gear shafts and that constitute the gear reduction mechanism 20. The lower end of the large-diameter first intermediate gear 71 is sprung up so that the remaining gears of the gear reduction mechanism 20, that is, the input gear 70, the second intermediate gear 72, and the output gear 73 are viewed from the side. Therefore, the oil can be easily distributed around the transmission shaft 14 and the axle 15 disposed on both sides of the intermediate gear shaft 16 in a side view.

  An oil receiving portion 80 that receives oil repelled by the first intermediate gear 71 is located above the transmission shaft 14, the intermediate gear shaft 16, and the axle 15 and between the transmission shaft 14 and the axle 15 in a side view. Since the oil from the oil receiving portion 80 is guided to the transmission shaft 14 and the axle 15 shaft by the oil supply means 81 so as to be disposed, the transmission shaft 14 and the gear case 43 are arranged. Stable oil distribution and supply to the axle 15 can be performed.

  Further, since the center axis C2 of the intermediate gear shaft 16 is disposed lower than the center axis C1 of the transmission shaft 14 and the center axis C3 of the axle 15, the first intermediate gear 71 is connected to the gear case 43. It becomes easy to approach the bottom, and the first intermediate gear 71 can be downsized. In addition, the transmission shaft 14 and the axle 15 can be disposed close to the intermediate gear shaft 16, oil can be guided to the transmission shaft 14 and the axle 15 more efficiently, and the space between the shafts can be narrowed. Thus, the gear case 43 can be made compact.

  In addition, since a concave portion 78 is formed in the lower portion of the gear case 43 so as to make the lower portion of the intermediate gear shaft 16 the lowest, the amount of oil necessary for lubrication can be reduced, and the gear reduction mechanism. Friction due to oil agitation at 20 can be reduced, which can contribute to an improvement in power transmission efficiency.

  Further, the oil receiving portion 80 is formed in a bowl shape extending along the central axis C <b> 2 of the intermediate gear shaft 16 and open upward, and constitutes a part of the oil supply means 81 and is provided in the gear case 43. The oil guide wall 82 is disposed below the oil receiving portion 80 while crossing the oil receiving portion 80 in a plan view so as to receive the oil overflowing from the oil receiving portion 80 and guide it to the axle 15. Therefore, it is possible to increase the collection efficiency of the oil overflowing from the oil receiving portion 80 at the oil guide wall 82 and supply a sufficient amount of oil to the axle 15 side.

  In addition, since the oil guide wall 82 is formed at the upper end portion of the oil guide wall 82 at a portion located on the transmission shaft 14 side with respect to the oil receiving portion 80 in a side view, The collection efficiency of the oil overflowing from the oil receiving portion 80 to the oil guide wall 82 can be further increased.

  The gear case 43 includes at least a transmission case 21 that houses the belt-type continuously variable transmission 13 and at least a mechanical transmission 18 that is connected to the belt-type continuously variable transmission 13 in series and provided on the transmission shaft 14. A gear cover 44 that is partially connected to the transmission case 21 by forming a wet first transmission chamber 46 that accommodates the planetary gear mechanism 55 and the gear reduction mechanism 20 between the transmission case 21 and the transmission. A second accommodating chamber 47 is formed between the gear cover 44 and accommodates the shift clutch 19 that switches the gear position of the mechanical transmission 18 in accordance with the rotational speed of the shaft 14. And the clutch cover 45 coupled to the gear cover 44, and the oil receiving portion 80 is formed on the upper wall of a portion of the gear case 43 that forms the first transmission chamber 46 in plan view. 16 and An oil supply passage 82 is formed in the gear cover 44 and the clutch cover 45 so as to constitute part of the oil supply means 81 and guide the oil to the transmission shaft 14, and the oil receiving portion 80 and the oil supply passage 82. Since the connection portion is provided with a notch 87 for dropping oil toward the lower intermediate gear shaft 16 side, the oil from the oil receiving portion 80 is guided to the transmission shaft 14 side and also to the intermediate gear shaft 16. The intermediate gear shaft 16 can be lubricated with a simple configuration while the transmission shaft 14 is lubricated.

    Further, the other end of the transmission shaft 14 having an oil hole 88 coaxially guiding oil to the wet transmission clutch 19 and the mechanical transmission 18 is connected to the first bearing portion 45a of the clutch cover 45 via a bearing 54 with a seal. Since the oil receiving portion 80 and the oil hole 88 communicate with each other through a cylindrical oil supply passage 83, the oil from the oil supply passage 83 is outside the transmission clutch 19 where the oil is wet. By avoiding this, it is possible to contribute to reduction of rotational friction of the transmission clutch 19.

  Further, the gear cover 44 is provided with a third bearing portion 44 c that rotatably supports the other end portion of the intermediate gear shaft 16, and oil is returned from the second speed change chamber 47 to the first speed change chamber 46. And the second intermediate gears 71 and 72 are opposed to the return passage 90 disposed below the third bearing portion 44c in the axial direction and the opening end of the return passage 90 toward the first transmission chamber 46. Since the reinforcing rib 44e connecting the bottom wall of the gear cover 44 and the third bearing portion 44c is provided, the return passage 90 is a side wall interposed between the first and second transmission chambers 46 and 47 in the gear cover 44. It opens to the part surrounded by the bottom wall of the shift chamber forming wall 44a, the third bearing portion 44c, the reinforcing rib 44e, and the gear cover 44, which is the part, and the lower oil in the first shift chamber 46 is passed through the first intermediate Repel with gear 71 In spite of this, the influence of the rotation of the first intermediate gear 71 is prevented from reaching the return passage 90, preventing the backflow of oil from the return passage 90 to the second transmission chamber 47 side, Friction caused by the speed change clutch 19 can be further reduced by setting the two speed change chamber 47 in an environment close to a dry type.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

DESCRIPTION OF SYMBOLS 11 ... Crankcase 12 ... Crankshaft 13 ... Belt type continuously variable transmission 14 ... Transmission shaft 15 which is an input gear shaft ... Axle 16 which is an output gear shaft ... Intermediate gear Shaft 18 ... Mechanical transmission 19 ... Shift clutch 20 ... Gear reduction mechanism 21 ... Transmission case 22c ... Second bearing portion 43 ... Gear case 44 ... Gear cover 44c ... 3rd bearing part 44e ... Reinforcement rib 45 ... Clutch cover 45a ... 1st bearing part 46 ... 1st transmission chamber 47 ... 2nd storage chamber 54 ... Bearing with seal 70 ... input gears 71, 72 ... intermediate gear 73 ... output gear 78 ... concave 80 ... oil receiving part 81 ... oil supply means 82 ... oil guide wall 82a ... projection Portion 83 ... Refueling passage 87 ... Notch 88 ... Yl holes 90 ... back center axis of the axle is the center axis C3 ... output gear shaft of the central axis line C2 ... intermediate gear shaft of the axle is a passage C1 ... input gear shaft

Claims (12)

An input gear shaft (14) to which power from the crankshaft (12) is transmitted, and an intermediate gear shaft (16) and an output gear shaft (15) having axes parallel to the input gear shaft (14) are rotatable. The gear case (43) supported on the input gear (70) receives the rotational power from the input gear shaft (14) and rotates about the central axis (C1) of the input gear shaft (14) from the intermediate gear (70). A gear reduction mechanism (20) that constitutes a power transmission path from the gear shaft (16) to the output gear shaft (15) is accommodated and oil is stored,
The gear case (43) rotates around a central axis of a specific gear shaft that is one of the input gear shaft (14), the intermediate gear shaft (16), and the output gear shaft (15). Thus, an oil receiving part (80) that receives oil splashed by a gear (71) that constitutes a part of the gear reduction mechanism (20),
Oil supply means for guiding oil from the oil receiving portion (80) to a gear shaft side other than the specific gear shaft among the input gear shaft (14), the intermediate gear shaft (16) and the output gear shaft (15). (81) and the lubricating structure of the gear case,
The intermediate gear shaft (16), which is the specific gear shaft, is disposed between the input gear shaft (14) and the output gear shaft (15) in a side view,
Of the plurality of gears (70, 71, 72, 73) constituting the gear reduction mechanism (20), the lower end of the intermediate gear (71) provided on the intermediate gear shaft (16) causes the oil to spring up. The lower side of the remaining gears (70, 72, 73) of the gear reduction mechanism (20) is disposed at a lower position in a side view, and the oil receiving portion (80) is in the input gear shaft (14) in a side view. And above the intermediate gear shaft (16) and the output gear shaft (15) and between the input gear shaft (14) and the output gear shaft (15) ,
The oil receiving portion (80) is formed in a bowl shape having a cross section extending along the central axis (C2) of the intermediate gear shaft (16) and opened upward, and is a part of the oil supply means (81) And an oil guide wall (82) provided in the gear case (43) receives oil overflowing from the oil receiving portion (80) and guides it to the output gear shaft (15). the lubrication structure of the gear casing, characterized in Rukoto disposed below the oil receiving portion the oil receiving portion while traversing (80) (80) in view. The oil receiving portion on the side surface as viewed the input gear shaft than (80) (14) at the upper end of the oil guide wall portion located (82) on the side, the oil receiving portion (80) above the lubrication structure of the gear case according to claim 1, wherein a protrusion protruding (82a) is formed. An input gear shaft (14) to which power from the crankshaft (12) is transmitted, and an intermediate gear shaft (16) and an output gear shaft (15) having axes parallel to the input gear shaft (14) are rotatable. The gear case (43) supported on the input gear (70) receives the rotational power from the input gear shaft (14) and rotates about the central axis (C1) of the input gear shaft (14) from the intermediate gear (70). A gear reduction mechanism (20) that constitutes a power transmission path from the gear shaft (16) to the output gear shaft (15) is accommodated and oil is stored,
The gear case (43) rotates around a central axis of a specific gear shaft that is one of the input gear shaft (14), the intermediate gear shaft (16), and the output gear shaft (15). Thus, an oil receiving part (80) that receives oil splashed by a gear (71) that constitutes a part of the gear reduction mechanism (20),
Oil supply means for guiding oil from the oil receiving portion (80) to a gear shaft side other than the specific gear shaft among the input gear shaft (14), the intermediate gear shaft (16) and the output gear shaft (15). (81) and the lubricating structure of the gear case,
The intermediate gear shaft (16), which is the specific gear shaft, is disposed between the input gear shaft (14) and the output gear shaft (15) in a side view,
Of the plurality of gears (70, 71, 72, 73) constituting the gear reduction mechanism (20), the lower end of the intermediate gear (71) provided on the intermediate gear shaft (16) causes the oil to spring up. The lower side of the remaining gears (70, 72, 73) of the gear reduction mechanism (20) is disposed at a lower position in a side view, and the oil receiving portion (80) is in the input gear shaft (14) in a side view. And above the intermediate gear shaft (16) and the output gear shaft (15) and between the input gear shaft (14) and the output gear shaft (15),
The gear case (43) is a belt type continuously variable provided between the crankshaft (12) rotatably supported by the crankcase (11) of the engine (E) and one end of the input gear shaft (14). A transmission case (21) that houses the transmission (13) and is connected to the crankcase (11), and the input gear shaft (14) connected in series to the belt-type continuously variable transmission (13). A wet first transmission chamber (46) for housing at least a part of the mechanical transmission (18) and the gear reduction mechanism (20) provided in the transmission case (21). A gear cover (44) coupled to the transmission case (21) and a transmission clutch (19) for switching the gear position of the mechanical transmission (18) according to the rotational speed of the input gear shaft (14). The first shift chamber (4 ) And consists out with a clutch cover coupled second accommodating chamber partitioned (47) into the gear cover (44) is formed between the gear cover (44) (45),
The oil receiving portion (80) is formed so as to overlap the intermediate gear shaft (16) in a plan view on an upper wall of a portion of the gear case (43) forming the first transmission chamber (46),
An oil supply passage (83) that constitutes a part of the oil supply means (81) and guides oil to the input gear shaft (14) is formed in the gear cover (44) and the clutch cover (45),
The connecting portion of the oil receiving portion (80) and said oil supply passage (83), you characterized in that notches for dropping the oil downward of the intermediate gear shaft (16) side (87) is provided teeth Car case lubrication structure. The gear case (43) is a belt type continuously variable provided between the crankshaft (12) rotatably supported by the crankcase (11) of the engine (E) and one end of the input gear shaft (14). A transmission case (21) that houses the transmission (13) and is connected to the crankcase (11);
A wet type housing which is connected in series to the belt type continuously variable transmission (13) and houses at least a part of the mechanical transmission (18) provided on the input gear shaft (14) and the gear reduction mechanism (20). A gear cover (44) that forms a first transmission chamber (46) between the transmission case (21) and is coupled to the transmission case (21);
A second housing that is separated from the first transmission chamber (46) by housing a transmission clutch (19) that switches the gear position of the mechanical transmission (18) according to the rotational speed of the input gear shaft (14). A chamber cover (47) formed between the gear cover (44) and a clutch cover (45) coupled to the gear cover (44);
The oil receiving portion (80) is formed so as to overlap the intermediate gear shaft (16) in a plan view on an upper wall of a portion of the gear case (43) forming the first transmission chamber (46), An oil supply passage (83) constituting a part of the oil supply means (81) and guiding oil to the input gear shaft (14) is formed in the gear cover (44) and the clutch cover (45), and the oil receiver the connection of the parts (80) and said oil supply passage (83), cutout to drop the oil downward of the intermediate gear shaft (16) side (87) according to claim 1 Symbol mounting, characterized in that are provided Gear case lubrication structure. The upper end portion of the oil guide wall (82) protrudes above the oil receiving portion (80) at a portion located on the input gear shaft (14) side of the oil receiving portion (80) in a side view. The lubricating structure for a gear case according to claim 4, wherein a protruding portion (82a) is formed. The other end portion of the input gear shaft (14) having an oil hole (88) for guiding oil to the wet-type transmission clutch (19) and the mechanical transmission (18) is connected to the clutch cover (45). The oil receiving portion (80) and the first oil receiving portion (80), which are rotatably supported by a first bearing portion (45a) provided in a seal via a bearing (54) with a seal, and are formed in a cylindrical shape. The gear case lubricating structure according to any one of claims 3 to 5, wherein the oil holes (88) communicate with each other. The gear cover (44) is configured to rotatably support the other end portion of the intermediate gear shaft (16) whose one end portion is supported by a second bearing portion (22c) provided in the transmission case (21). The third bearing portion (44c) and the intermediate gears (71, 72) are displaced in the axial direction so as to return oil from the second transmission chamber (47) to the first transmission chamber (46). 44c), a return passage (90), a bottom wall of the gear cover (44) and a third wall facing the opening end of the return passage (90) toward the first transmission chamber (46). The lubricating structure for a gear case according to any one of claims 3 to 6, further comprising a reinforcing rib (44e) connecting the bearing portions (44c). An input gear shaft (14) to which power from the crankshaft (12) is transmitted, and an intermediate gear shaft (16) and an output gear shaft (15) having axes parallel to the input gear shaft (14) are rotatable. The gear case (43) supported on the input gear (70) receives the rotational power from the input gear shaft (14) and rotates about the central axis (C1) of the input gear shaft (14) from the intermediate gear (70). A gear reduction mechanism (20) that constitutes a power transmission path from the gear shaft (16) to the output gear shaft (15) is accommodated and oil is stored,
The gear case (43) rotates around a central axis of a specific gear shaft that is one of the input gear shaft (14), the intermediate gear shaft (16), and the output gear shaft (15). Thus, an oil receiving part (80) that receives oil splashed by a gear (71) that constitutes a part of the gear reduction mechanism (20),
Oil supply means for guiding oil from the oil receiving portion (80) to a gear shaft side other than the specific gear shaft among the input gear shaft (14), the intermediate gear shaft (16) and the output gear shaft (15). (81) and the lubricating structure of the gear case,
The intermediate gear shaft (16), which is the specific gear shaft, is disposed between the input gear shaft (14) and the output gear shaft (15) in a side view,
Of the plurality of gears (70, 71, 72, 73) constituting the gear reduction mechanism (20), the lower end of the intermediate gear (71) provided on the intermediate gear shaft (16) causes the oil to spring up. The lower side of the remaining gears (70, 72, 73) of the gear reduction mechanism (20) is disposed at a lower position in a side view, and the oil receiving portion (80) is in the input gear shaft (14) in a side view. And above the intermediate gear shaft (16) and the output gear shaft (15) and between the input gear shaft (14) and the output gear shaft (15),
The lubrication structure of a gear case, wherein the oil supply means (81) guides oil from the oil receiving portion (80) to the input gear shaft (14) and the output gear shaft (15). The gear case lubricating structure according to claim 8, wherein the oil receiving portion (80) is provided at a position overlapping the intermediate gear shaft in plan view. The oil receiving portion (80) is formed in a bowl shape having a cross section opened upward, and constitutes part of the oil supply means (81) to be provided on the gear case (43). 10. The gear case lubricating structure according to claim 8, wherein the lubricating structure is arranged so as to cross a lower portion of the oil receiving portion in a plan view. The lower portion of the gear case (43) is formed with a recess (78) recessed downward so that the lower portion of the intermediate gear shaft (16) is lowest . A lubrication structure of a gear case according to any one of the above. The central axis (C2) of the intermediate gear shaft (16) is disposed lower than the central axis (C1) of the input gear shaft (14) and the central axis (C3) of the output gear shaft (15) in a side view. The gear case lubricating structure according to any one of claims 1 to 11, wherein:

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