JP6443108B2 - Unit swing type engine unit - Google Patents

Description

  The present invention relates to a unit swing type engine unit, and more particularly to a unit swing type engine unit having a dry sump type lubrication mechanism.

  Conventionally, an oil tank for storing oil that lubricates members in an internal combustion engine is integrally provided at the rear of the crankcase, and a unit swing type engine unit (power unit) is mounted on the body frame so that it can swing up and down together with the rear wheel. ) Has been proposed (see, for example, Patent Document 1). In this motorcycle engine unit, since the oil tank is provided integrally with the crankcase, even when the engine unit swings, the oil flows smoothly between the crankcase and the oil tank. be able to.

JP 2006-44438 A

  However, in the motorcycle engine unit described in Patent Document 1, the first oil passage communicating from the crankcase to the oil tank, the second oil passage communicating from the oil tank to the oil pump and the oil filter, etc. It is arranged on the lower side of the shaft. For this reason, the crankshaft disposed in the crankcase is disposed at substantially the same height as the rear wheelshaft supported by the motorcycle engine unit in a side view.

  On the other hand, in a motorcycle equipped with a unit swing type engine unit, the seat height (seat height) disposed above the engine unit is reduced and the capacity of the luggage space utilizing the space below the seat is increased. It is requested to expand. The layout around the engine unit has been devised to meet such demands. However, there are certain limits to the reduction in seat height and the increase in luggage space capacity due to the layout around the engine unit. For this reason, when the configuration of a general internal combustion engine is employed, it is difficult to further reduce the seat height and increase the capacity of the luggage space due to the layout around the engine unit.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a unit swing type engine unit capable of realizing a reduction in seat height and an increase in capacity of a luggage space.

Unit swing type engine unit of the present invention comprises an internal combustion engine having a crankcase and a cylinder, an oil tank for storing oil for lubricating the crankcase and the cylinder internal member, wherein the oil tank, the The engine unit is a unit swing type engine unit that is disposed outside the crank chamber in the crankcase and in which the center of the crankshaft disposed in the crankcase is disposed below the center of the rear wheel shaft. The crankcase is composed of a pair of case members divided in the vehicle width direction, the oil tank is disposed on the rear side of one case member, and the one case member is in a top view, The crank chamber formed inside the crank chamber, and the crankcase outside of the one case member in the vehicle width direction. And a extending portion extending rearward from the chamber portion, the oil tank, characterized in that it is disposed at a corner of the connecting portion between said crank chamber portion said extending portion.

According to this configuration, since the oil tank is disposed outside the crank chamber and the center of the crankshaft is disposed below the center axis of the rear wheel, there is a restriction on the layout of the oil tank. The position of the crankcase can be lowered. As a result, a space can be formed above the crankcase compared to a conventional unit swing type engine unit in which the center of the crankshaft is arranged at a height substantially equal to the center axis of the rear wheel. It is possible to reduce the height of the seat disposed above the seat, and to increase the capacity of the luggage space using the space below the seat. Further, the center of gravity of the internal combustion engine can be lowered by lowering the position of the crankshaft, so that it is possible to improve the running stability of the vehicle. The crankcase includes a pair of case members divided in the vehicle width direction, and the oil tank is disposed on the rear side of one case member. Since the oil tank is arranged only on the rear side of one case member, the space required for the arrangement of the oil tank can be reduced, thereby reducing the influence on the layout of the components around the engine unit. Is possible. Further, the one case member includes a crank chamber portion in which the crank chamber is formed and a rear side extending from the crank chamber portion on the outer side in the vehicle width direction of the one case member in a top view. And the oil tank is disposed at a corner portion of a connection portion between the crank chamber portion and the extension portion. Since the oil tank is disposed at the corner portion of the connecting portion between the crank chamber portion and the extension portion of the one case member, the oil tank can be disposed by utilizing a space that easily becomes a dead space.

  In particular, in the unit swing type engine unit of the present invention, it is preferable that the oil tank is provided integrally with the one case member. In this case, the oil hose connected from the oil tank to the crankcase of the crankcase can be omitted, and the oil passage from the oil tank to the lubrication location in the crankcase or cylinder can be shortened.

  Further, the unit swing type engine unit of the present invention has a scavenging pump and a feed pump for pumping oil, and the scavenging pump and the feed pump are arranged side by side in the front and rear of the vehicle below the crankshaft. It is preferable. In this case, since the scavenging pump and the feed pump are arranged on the lower side of the crankshaft, the center of gravity of the internal combustion engine can be lowered, and the running stability can be further improved. In addition, since the scavenging pump and the feed pump are arranged side by side in the front and rear of the vehicle, parts for driving these pumps can be shared, so the number of parts for driving the pumps can be reduced. It becomes. Further, as compared with the case where the scavenging pump and the feed pump are arranged apart from each other, the configuration of the oil passage through which oil is pumped by these pumps can be simplified.

  In particular, in the unit swing type engine unit of the present invention, it is preferable that the feed pump receives a rotational force from the crankshaft and transmits the rotational force to the scavenging pump. In this case, since the feed pump and the scavenging pump can be rotated in accordance with the rotation of the crankshaft, the components that supply the feed pump and the scavenging pump can be omitted, and the number of parts and the manufacturing cost can be reduced. It becomes possible to reduce.

  Furthermore, in the unit swing type engine unit of the present invention, a part of the oil passage communicating with the oil tank is provided at a position including a mating surface between the one case member and the other case member of the crankcase. Is preferred. In this case, since part of the oil passage communicating with the oil tank is provided at a position including the mating surfaces of the pair of case members, the oil passage is formed when the case member is manufactured by casting using a mold or the like. This eliminates the need for special processing for forming the oil passage.

  For example, in the unit swing type engine unit of the present invention, the one case member and the other case member are provided with grooves arranged to face each other, and a part of the oil passage is formed by the one case member. And the other case member. In this case, since a part of the oil passage is formed by the groove portions that are arranged to face each other when the pair of case members are coupled, the cross-sectional area of the oil passage can be increased, and the crankcase and It becomes possible to improve the lubrication performance for the members inside the cylinder.

  According to the present invention, it is possible to reduce the seat height and increase the capacity of the luggage space.

1 is a side view of a part of a motorcycle to which a unit swing type engine unit according to the present embodiment is applied. It is a side view of the unit swing type engine unit concerning this embodiment. It is a side view of the unit swing type engine unit concerning this embodiment. It is a schematic diagram for demonstrating the internal structure of the unit swing type engine unit which concerns on this Embodiment. It is a top view of the unit swing type engine unit concerning this embodiment. It is a side view of the left case which the unit swing type engine unit concerning this embodiment has. It is a side view of the left case which the unit swing type engine unit concerning this embodiment has. It is a side view of the right case which the unit swing type engine unit concerning this embodiment has. It is a side view of the right case which the unit swing type engine unit concerning this embodiment has. It is a top view of the crankcase which the unit swing type engine unit concerning this embodiment has. It is a side view of a part of a motorcycle to which a unit swing type engine unit according to a reference example is applied.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, the case where the unit swing type engine unit according to the present invention is applied to a motorcycle will be described. However, the vehicle to which the present invention is applied is not limited to a motorcycle but can be changed as appropriate. For example, the present invention can be applied to an automatic tricycle or an automatic four-wheel vehicle.

  FIG. 1 is a side view of a part of a motorcycle to which a unit swing type engine unit according to the present embodiment is applied. Although FIG. 1 shows a case where a unit swing type engine unit is applied to a scooter type motorcycle, the present invention is not limited to this. Further, FIG. 1 shows only some components around the unit swing type engine unit. In the following description, the front of the vehicle is indicated by an arrow FR, the rear of the vehicle is indicated by an arrow RE, the left side of the vehicle is indicated by an arrow L, and the right side of the vehicle is indicated by an arrow R.

  As shown in FIG. 1, a unit swing type engine unit (hereinafter referred to as “engine unit” as appropriate) 1 is disposed on the lower side of the vehicle and on the rear side from the center of the vehicle. The engine unit 1 is supported on a body frame (not shown) so as to be swingable in the vertical direction. The engine unit 1 is configured by integrating an internal combustion engine 2 having a dry sump lubrication mechanism and a transmission 3. The internal combustion engine 2 is constituted by, for example, a 4-stroke cycle single cylinder air-cooled internal combustion engine. The transmission 3 includes, for example, a V-belt continuously variable transmission 31 and a transmission case 32 (see FIG. 4 for the V-belt continuously variable transmission 31). A part of the internal combustion engine 2 (more specifically, a left case 21L described later) supports a rear wheel 4 that receives a driving force via the transmission 3 in the vicinity of the rear end portion.

  An air cleaner 5 and a throttle body 6 are provided above the engine unit 1. The air cleaner 5 and the throttle body 6 are attached to the engine unit 1 via a bracket, and are configured to be able to swing together with the engine unit 1. The air cleaner 5 cleans the outside air taken in during traveling by a built-in air filter and supplies the air to the throttle body 6.

  The throttle body 6 is connected to the air cleaner 5 via a connecting tube 61. The throttle body 6 includes a throttle valve (not shown) inside. The throttle body 6 adjusts the opening / closing state of the throttle valve in accordance with the opening / closing operation of the throttle by the driver, so that the internal combustion engine 2 (more specifically, the combustion chamber in the internal combustion engine 2) from the air cleaner 5 side. Control the amount of air supplied.

  Above these air cleaner 5 and throttle body 6, a seat 7 and a luggage box 8 on which a driver sits are arranged. The seat 7 is attached to a support portion 81 provided above the front portion of the luggage box 8. The seat 7 is attached so that the rear end side can be opened and closed up and down with the support portion 81 as a rotation fulcrum.

  The luggage box 8 is disposed inside an exterior component (not shown) disposed on the lower side of the seat 7. The luggage box 8 has a shape opened to the upper side. The luggage box 8 is configured to be able to accommodate a luggage such as a helmet in a state where the seat 7 is opened with the support portion 81 as a rotation fulcrum.

  Here, the configuration of the engine unit 1 according to the present embodiment will be described with reference to FIGS. 2 and 3 are side views of the engine unit 1 according to the present embodiment. FIG. 4 is a schematic diagram for explaining the internal configuration of the engine unit 1 according to the present embodiment. 2, the engine unit 1 is shown from the left side of the vehicle, and in FIG. 3, the engine unit 1 is shown from the right side of the vehicle.

  As shown in FIGS. 2 and 3, the engine unit 1 is composed of an internal combustion engine 2 and a transmission 3. The internal combustion engine 2 includes a crankcase 21, a cylinder block 22, a cylinder head 23, and a cylinder head cover 24. The cylinder block 22 is coupled to the front end portion of the crankcase 21. The cylinder head 23 is coupled to the front end portion of the cylinder block 22. The cylinder head cover 24 is coupled to the front end portion of the cylinder head 23. The transmission 3 includes a transmission case 32 joined to the crankcase 21 and a V-belt continuously variable transmission 31 housed in the transmission case 32 (about the V-belt continuously variable transmission 31). (See FIG. 4).

  Inside the engine unit 1, as shown in FIG. 4, a crankshaft 90 is rotatably supported in the crankcase 21. A cylinder hole 221 is formed in the cylinder block 22. A piston 91 is slidably disposed in the cylinder hole 221. Both ends of a connecting rod 92 are rotatably connected to the crankshaft 90 and the piston 91 via a crankpin 90a and a piston pin 91a, respectively. As the piston 91 reciprocates, the crankshaft 90 is rotationally driven within the crank chamber 93.

  The crankshaft 90 is provided with a drive pulley 31 a for the V-belt continuously variable transmission 31. The crankshaft 90 constitutes a drive shaft for the V-belt continuously variable transmission 31. The driven shaft 31 b of the V-belt continuously variable transmission 31 is rotatably supported by the transmission case 32. The driven shaft 31b is provided with a driven pulley 31c of the V-belt continuously variable transmission 31 via a centrifugal clutch (not shown). An endless V-belt 31d is bridged between the drive pulley 31a and the driven pulley 31c.

  A driven shaft pinion 31 e is formed on the driven shaft 31 b of the V-belt continuously variable transmission 31. An intermediate gear 31f meshes with the driven shaft pinion 31e. A rear wheel gear 41 provided on the rear wheel shaft 40 meshes with the intermediate gear 31f. The rear wheel 4 is integrally coupled to the rear wheel shaft 40 (see FIG. 1).

  A combustion chamber 94 is formed at the rear end of the cylinder head 23. An intake port 95 connected to the combustion chamber 94 is formed in the upper part of the cylinder head 23. On the other hand, an exhaust port 96 connected to the combustion chamber 94 is formed in the lower portion of the cylinder head 23. Further, the cylinder head 23 is provided with an intake valve 97 for opening and closing an opening on the combustion chamber 94 side in the intake port 95 and an exhaust valve 98 for opening and closing an opening on the combustion chamber 94 side in the exhaust port 96. .

  The throttle body 6 is connected to the intake port 95 via an intake pipe (not shown) (see FIG. 1). A muffler is connected to the exhaust port 96 via an exhaust pipe (not shown). A valve operating chamber 99 is formed between the cylinder head 23 and the cylinder head cover 24. The intake valve 97 and the exhaust valve 98 disposed in the cylinder head 23 are driven to open and close by a valve operating device (not shown) disposed in the valve operating chamber 99.

  As shown in FIG. 4, in the engine unit 1, the center C1 of the crankshaft 90 disposed in the crankcase 21 is disposed below the center C2 of the rear wheel shaft 40 in a side view. The center C1 of the crankshaft 90 is disposed below the center C3 of the piston pin 91a in a side view.

  FIG. 5 is a top view of the engine unit according to the present embodiment. As shown in FIG. 5, the crankcase 21 includes a pair of left and right case members that are divided in the vehicle width direction. Hereinafter, the case member disposed on the left side is referred to as a left case 21L, and the case member disposed on the right side is referred to as a right case 21R. The left case 21L generally has a shape opened to the right side, and the right case 21R has a shape opened to the left side (see FIGS. 7 and 9). The crankcase 21 is formed by joining (connecting) the right end surface of the left case 21L and the left end surface of the right case 21R. A crank chamber 93 to be described later is configured by a space formed inside by joining the left case 21L and the right case 21R.

  The left case 21L includes a crank chamber portion 211L that defines a crank chamber 93 therein, and a belt chamber portion that extends rearward from the crank chamber portion 211L on the outer side (left side) in the vehicle width direction of the crank chamber 211L. (Extending portion) 212L, and generally has an L shape in a top view. The crank chamber portion 211L and the belt chamber portion 212L are integrally provided.

  The left case 21L is provided with an oil tank 213L. The oil tank 213L has a box shape with a triangular cross section when viewed from above. The oil tank 213L is provided at the corner of the connecting portion between the crank chamber 211L and the best chamber 212L. That is, the oil tank 213L is provided only outside the crank chamber 93 and behind the left case 21L. Further, the oil tank 213L is provided integrally with the crank chamber portion 211L and the belt chamber portion 212L.

  Thus, by arranging the oil tank 213L only on the rear side of the left case 21L, the space required for the arrangement of the oil tank 213L can be reduced, and the influence on the layout of the components around the engine unit 1 can be reduced. Can be reduced. In addition, since the oil tank 213L is disposed at the corner of the connection portion between the crank chamber portion 211L and the best chamber portion 212L in the left case 21, a space that tends to become a dead space can be effectively utilized. Furthermore, by providing the oil tank 213L integrally with the crank chamber portion 211L and the belt chamber portion 212L, an oil hose connected from the oil tank 213L to the crank chamber 93 of the crankcase 21 can be omitted, and the crank from the oil tank 213L can be omitted. The oil passage for pressure-feeding oil to the lubrication location in the case 21 and the cylinder (cylinder block 22, cylinder head 23, cylinder head cover 24) can be shortened.

  Further, an oil filter 214 is attached to the side surface of the left case 21L (see FIG. 2). The oil filter 214 removes impurities of oil supplied through oil passages OP2 and OP5 described later (see FIG. 10). The oil from which impurities have been removed is used to lubricate members in the crankcase 21 and the cylinder (cylinder block 22, cylinder head 23, cylinder head cover 24).

  A transmission case 32 constituting the transmission 3 is attached to the left case 21L so as to close the opening of the belt chamber 212L. The V-belt continuously variable transmission 31 is accommodated in a space formed inside the belt chamber portion 212L and the transmission case 32 (see FIG. 4). A rear wheel shaft support portion 215L is provided on the right side of the rear end portion of the belt chamber portion 212L. The rear wheel shaft support portion 215L supports the rear wheel shaft 40 that is integrally coupled to the rear wheel 4 (see FIG. 4).

  The right case 21R has a crank chamber portion 211R that defines a crank chamber 93 therein, like the left case 21L. The right case 21R is provided with an oil pump 10 (see FIG. 4). The oil pump 10 includes a scavenging pump 101 and a feed pump 102. The scavenging pump 101 serves to suck up the oil that has flowed down to the bottom surface of the crank chamber 93 and pump it to the oil tank 213L. The feed pump 102 plays a role of pumping oil stored in the oil tank 213L to members in the crankcase 21 and the cylinder (cylinder block 22, cylinder head 23, cylinder head cover 24).

  These scavenging pump 101 and feed pump 102 are arranged side by side in the vehicle front-rear direction below the crankshaft 90. The scavenging pump 101 has a rotational shaft disposed slightly rearward of the crankshaft 90, and the feed pump 102 has a rotational shaft disposed slightly forward of the crankshaft 90. The rotating shaft of the scavenging pump 101 and the rotating shaft of the feed pump 102 are arranged at substantially the same height.

  The feed pump 102 receives a rotational force from the crankshaft 90. The feed pump 102 transmits the rotational force received from the crankshaft 90 to the scavenging pump 101. That is, when the crankshaft 90 rotates, the feed pump 102 rotates, and the scavenging pump 101 rotates in response to the rotation of the feed pump 102. In this way, by rotating the feed pump 102 and the scavenging pump 103 in accordance with the rotation of the crankshaft 90, it is possible to omit components that supply rotational force to the feed pump 102 and the scavenging pump 101. Costs can be reduced.

  In the engine unit 1 having such a configuration, when the fuel / air mixture supplied into the combustion chamber 94 is combusted by an ignition device (not shown), the piston 91 reciprocates in the cylinder hole 221. As the piston 91 reciprocates, the crankshaft 90 connected via the connecting rod 92 rotates. When the drive pulley 31a rotates according to the rotation of the crankshaft 90, the endless V-belt 31d spanned between the drive pulley 31a and the driven pulley 31c rotates. The rotation of the endless V-belt 31d is transmitted to the rear wheel shaft 40 via the intermediate gear 31f and the rear wheel gear 41. Then, the rear wheel 40 integrally coupled to the rear wheel shaft 40 rotates.

  On the other hand, as the crankshaft 90 rotates, the scavenging pump 101 and the feed pump 102 rotate. As the scavenging pump 101 rotates, the oil that has flowed down to the bottom surface of the crank chamber 93 is sucked up and pumped to the oil tank 213L. Further, the rotation of the feed pump 102 causes the oil stored in the oil tank 213L to be pumped to members in the crankcase 21 and the cylinder (cylinder block 22, cylinder head 23, cylinder head cover 24).

  Hereinafter, the oil pressure feeding path in the engine unit 1 according to the present embodiment will be described with reference to FIGS. 6 to 10, the oil passage formed in the crankcase 21 (the left case 21L and the right case 21R) is indicated by a broken line.

  6 and 7 are side views of the left case 21L of the engine unit 1 according to the present embodiment. In FIG. 6, the left case 21L is shown from the outside (left side), and in FIG. 7, the left case 21L is shown from the inside (right side). 8 and 9 are side views of the right case 21R included in the engine unit 1 according to the present embodiment. In FIG. 8, the right case 21R is shown from the outside (right side), and in FIG. 9, the right case 21R is shown from the inside (left side). FIG. 10 is a top view of the crankcase 21 included in the engine unit 1 according to the present embodiment.

  As shown in FIGS. 6 and 7, an oil passage OP <b> 1 that communicates from the oil tank 213 </ b> L to the feed pump 101 is formed in the left case 21 </ b> L. As shown in FIG. 10, the oil passage OP1 is provided as a groove extending from the vicinity of the lower end of the oil tank 213L toward the front side at the joint surface of the left case 21L to the right case 21R. The oil passage OP1 is disposed to face an oil passage OP4 of the right case 21R described later.

  Further, an oil passage OP2 for communicating from the feed pump 101 to the oil filter 214 is formed on the front side of the left case 21L. As shown in FIG. 10, the oil passage OP2 extends from the joint surface of the left case 21L to the right case 21R toward the left side, and extends toward the front side near the center of the left case 21L. ing. The front end of the oil passage OP2 is connected to the oil filter 214.

  Further, an oil passage OP3 for communicating from the scavenging pump 101 to the oil tank 213L is formed on the rear side of the left case 21L. As shown in FIG. 10, the oil passage OP3 is formed to extend from the joint surface of the left case 21L to the right case 21R toward the left side and from the vicinity of the lower end portion of the left case 21L to the upper side. ing. The oil passage OP31 constituting the oil passage OP3 is formed to extend in the vehicle width direction on the lower side of the oil tank 213L. The oil passage OP32 constituting the oil passage OP3 is formed to extend to the vicinity of the upper end portion of the oil tank 213L outside the oil tank 213L. The upper end of the oil passage OP32 is connected to an oil supply hole OH formed in the oil tank 213L (see FIG. 7).

  As shown in FIGS. 8 and 9, the right case 21 </ b> R is formed with an oil passage OP <b> 4 that communicates from the oil tank 213 </ b> L to the feed pump 101. As shown in FIG. 10, the oil passage OP4 is provided as a groove portion extending from the vicinity of the lower end portion of the oil tank 213L toward the front side at the joint surface of the right case 21R to the left case 21L. The oil passage OP4 is disposed to face the oil passage OP1 of the left case 21L. The oil passage OP4 is formed to bend to the right side of the right case 21R at the front end thereof, and is connected to the feed pump 101.

  An oil passage OP5 that communicates from the feed pump 102 to the oil filter 214 is formed on the front side of the right case 21R. As shown in FIG. 10, the oil passage OP5 is formed so as to extend from the feed pump 102 toward the joining surface side of the left case 21L. The tip (left end) of the oil passage OP5 is connected to the oil passage OP2 of the left case 21L.

  Further, an oil passage OP6 that communicates from the bottom surface of the crank chamber 93 to the oil tank 213L via the scavenging pump 101 is formed on the rear side of the right case 21R. The oil passage OP6 includes an oil passage OP61 formed so as to extend in the vertical direction, and an oil passage OP62 formed so as to extend from the scavenging pump 101 toward the joining surface side with respect to the left case 21L (see FIG. 10). The lower end portion of the oil passage OP61 is open facing the bottom surface of the crank chamber 93.

  As described above, when the crankshaft 90 is rotated by combustion of the mixer in the combustion chamber 94, the scavenging pump 101 is rotated via the feed pump 102. The oil flowing down from the lower end of the oil passage OP61 to the bottom surface of the crank chamber 93 is sucked up by the rotation of the scavenging pump 101. The oil sucked from the lower end of the oil passage OP61 is sent out to the oil passage OP3 through the oil passage OP62, and supplied to the oil tank 213L through the oil supply hole OH.

  On the other hand, the feed pump 102 rotates according to the rotation of the crankshaft 90. The oil stored in the oil tank 213L is drawn to the feed pump 101 through the oil passages OP1 and OP4 by the rotation of the feed pump 101. The oil drawn from the oil tank 213L is sent to the oil filter 214 through the oil passages OP5 and OP2. After the impurities in the oil are removed by the oil filter 214, the oil is sent to members in the crankcase 21 and the cylinder (cylinder block 22, cylinder head 23, cylinder head cover 24).

  As described above, in the engine unit 1, the oil that has flowed down to the bottom surface of the crank chamber 93 via the scavenging pump 101 is supplied to the oil tank 213 </ b> L, and the oil in the oil tank 213 </ b> L is supplied to the crankcase 21 via the feed pump 102. And it is sent out to the lubrication part in the cylinder. For this reason, the oil tank 213 </ b> L is arranged outside the crank chamber 93 to ensure the degree of freedom of layout in the crank chamber 93. And the position of the crankshaft 90 arrange | positioned in the crankcase 21 is made low.

  That is, in the engine unit 1 according to the present embodiment, the oil tank 213L is disposed outside the crank chamber 93, and the center C1 of the crankshaft 90 is disposed below the center C2 of the rear wheel shaft 40. (See FIG. 1). For this reason, the position of the crankcase 21 can be lowered without being restricted by the layout of the oil tank 213L. As a result, a space is formed above the crankcase 21 as compared with a conventional engine unit (unit swing type engine unit) in which the center C1 of the crankshaft 90 is disposed at substantially the same height as the center C2 of the rear wheel shaft 40. can do. As a result, the height of the seat 7 disposed above the engine unit 1 can be lowered, and the capacity of the luggage box 8 utilizing the space below the seat can be increased.

  Further, in the engine unit 1 according to the present embodiment, the center C1 of the crankshaft 90 is disposed below the center C2 of the rear wheel shaft 40, so that the center of gravity of the internal combustion engine 2 can be lowered. As a result, the running stability of the vehicle can be improved.

  FIG. 11 is a side view of a part of a motorcycle to which the engine unit according to the reference example is applied. In FIG. 11, except for the engine unit, for convenience of explanation, the same reference numerals as those of the engine unit 1 according to the present embodiment are given. Further, FIG. 11 shows a motorcycle including the engine unit 11 in which the center C1 of the crankshaft 90 is disposed at substantially the same height as the center C2 of the rear wheel shaft 40. Further, FIG. 11 shows a case where the seat 7 and the luggage box 8 are arranged at the same height as the motorcycle shown in FIG. 1 for convenience of explanation.

  As can be seen from a comparison between FIG. 1 and FIG. 11, in the motorcycle according to the reference example, the center C <b> 1 of the crankshaft 90 in the engine unit 11 is substantially equal to the center C <b> 2 of the rear wheel shaft 40. For this reason, the throttle valve 6 attached to the upper side of the engine unit 11 is disposed at a high position. As a result, the space S11 between the luggage box 8 and the throttle valve 6 is reduced.

  On the other hand, in the engine unit 1 according to the present embodiment, the center C1 of the crankshaft 90 is disposed below the center C2 of the rear wheel shaft 40. For this reason, the throttle valve 6 attached to the upper side of the engine unit 11 can be arrange | positioned in a low position. Thereby, the space S1 between the luggage box 8 and the throttle valve 6 can be enlarged as compared with the motorcycle according to the reference example. As a result, the height of the seat 7 can be lowered, and the capacity of the luggage box 8 using the space below the seat 7 can be increased.

  Further, in the engine unit 1 according to the present embodiment, the scavenging pump 101 and the feed pump 102 are arranged side by side on the vehicle front and rear side below the crankshaft 90. Thereby, the center of gravity of the internal combustion engine 2 can be lowered, and the running stability can be further improved. Moreover, since the scavenging pump 101 and the feed pump 102 are arranged side by side in the front and rear of the vehicle, parts for driving these pumps 101 and 102 can be shared. Therefore, it is possible to reduce the number of parts. In addition, as compared with the case where the scavenging pump 101 and the feed pump 102 are arranged apart from each other, the configuration of the oil passage through which oil is pumped by these pumps 101 and 102 can be simplified.

  Furthermore, in the engine unit 1 according to the present embodiment, a part of the oil passages OP1 and OP4 communicating with the oil tank 213L is provided at a position including the joining surface (mating surface) between the left case 21L and the right case 21R. Yes. Accordingly, the oil passages OP1 and OP4 can be formed when the respective case members (the left case 21L and the right case 21R) are manufactured by casting using a mold or the like, so that these oil passages (OP1 and OP4) are formed. No special processing is required to form the film.

  In particular, the left case 21L and the right case 21R are provided with oil passages OP1 and OP4 as grooves disposed opposite to each other. The left case 21L and the right case 21R are joined (coupled) to the oil tank 213L. A communicating oil passage is formed. Accordingly, the cross-sectional area of the oil passage communicating with the oil tank 213L can be increased, and the lubrication performance for the members inside the crankcase 21 and the cylinder (cylinder block 22, cylinder head 23, cylinder head cover 24) can be improved. Is possible.

  In the above-described embodiment, the size, shape, and the like of each component illustrated in the accompanying drawings are not limited to this, and can be changed as appropriate within the scope of the effects of the present invention. In addition, the present invention can be appropriately modified and implemented without departing from the scope of the object.

  For example, in the above-described embodiment, a case has been described in which the crankcase 21 includes a pair of case members (the left case 21L and the right case 21R) that are divided in the vehicle width direction. However, the configuration of the crankcase 21 is not limited to this and can be changed as appropriate. For example, an integrated crankcase that is not divided in the vehicle width direction may be provided.

  Further, in the above-described embodiment, a case has been described in which the oil tank 213L is integrally provided at the corner of the connecting portion between the crank chamber 211L and the belt chamber 212L on the rear side of the left case 21L. . However, the configuration of the oil tank 213L is not limited to this, and can be changed as appropriate. For example, when the belt chamber portion is provided in the right case 21R, the belt chamber portion may be provided integrally at the same location of the right case 21R.

  Furthermore, the oil tank 213L is not necessarily integrated with the crankcase 21, and may be disposed separately from the left case 21L. Furthermore, the oil tank 213L may be disposed at a position other than the corner of the connecting portion between the crank chamber portion 211L and the belt chamber portion 212L. When the crankcase 21 (the left case 21L) does not have the belt chamber portion 212L and the transmission case 32 is joined to the crank chamber portion 211L, the corner portion of the connecting portion between the crank chamber portion 211L and the transmission case 32 is provided. You may make it arrange | position to a position.

  INDUSTRIAL APPLICABILITY The present invention has an effect of reducing the seat height and increasing the capacity of the luggage space, and is useful for a vehicle such as a motorcycle including a unit swing type engine unit.

1 unit swing type engine unit (engine unit)
2 Internal combustion engine 21 Crank case 21L Left case 21R Right case 211L, 211R Crank chamber portion 212L Belt chamber portion 213L Oil tank 214 Oil filter 22 Cylinder block 23 Cylinder head 24 Cylinder head cover 3 Transmission 31 V belt continuously variable transmission 32 Transmission Case 4 Rear wheel 40 Rear wheel shaft 5 Air cleaner 6 Throttle body 7 Seat 8 Luggage box 90 Crankshaft 91 Piston 91a Piston pin 93 Crank chamber C1 Center of crankshaft C2 Center of rear wheel shaft C3 Center of piston pin OP1 to OP6 Oil passage

Claims (6)

An internal combustion engine having a crankcase and a cylinder, and an oil tank for storing oil that lubricates members inside the crankcase and the cylinder ,
The oil tank, the disposed outside the crank chamber in the crankcase, the engine unit, the center of the crankshaft disposed within the crankcase, unit disposed below the center of the rear axle A swing type engine unit,
The crankcase is composed of a pair of case members that are divided in the vehicle width direction, and the oil tank is disposed on the rear side of one case member ,
The one case member includes a crank chamber portion in which the crank chamber is formed, and an extension extending rearward from the crank chamber portion on the outer side in the vehicle width direction of the one case member in a top view. And having an exit
The unit swing type engine unit , wherein the oil tank is disposed at a corner portion of a connection portion between the crank chamber portion and the extension portion . The unit swing type engine unit according to claim 1 , wherein the oil tank is provided integrally with the one case member. Oil has a scavenging pump and a feed pump for pumping, the scavenging pump and a feed pump, according to claim 1 or claim 2, wherein characterized in that it is arranged in the front and rear vehicle in the lower side of the crankshaft Unit swing type engine unit. The unit swing type engine unit according to claim 3 , wherein the feed pump receives a rotational force from the crankshaft and transmits the rotational force to the scavenging pump. The part of the oil passage communicating with the oil tank, from claim 1, characterized in that provided at a position including a mating surface of the one case member and the other case member of the crankcase of claim 4 The unit swing type engine unit according to any one of the above. The one case member and the other case member are provided with grooves that are arranged to face each other, and a part of the oil passage is formed by joining the one case member and the other case member. The unit swing type engine unit according to claim 5 , wherein the unit swing type engine unit is formed.

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