JP2012166582A - Protective structure of lower part of internal combustion engine in motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective structure of a lower part of an internal combustion engine in a motorcycle, which secures a large ground clearance while widely and continuously covering a rear power transmission case part in the front/rear direction from an oil pan part.SOLUTION: The motorcycle 1 includes a power unit 5 formed by integrating an internal combustion engine 2 and a power transmission case part 3, and holds a drive wheel 6 at a rear part of the power transmission case part. The motorcycle includes: a crank case bottom wall 111 located below a crankshaft 51 of the internal combustion engine for forming an oil pan part 110; a crank case rear wall 112 covering a rear side of the crankshaft; and main stand mounting boss parts 100L, 100R arranged behind the crank case rear wall. A base part 48a at the front end of a main stand 48 is supported to the main stand mounting boss parts through main stand support shafts 101, and the rear end of a protective plate 104 covering the oil pan part from the lower side is supported to the main stand support shafts.

Description

  The present invention relates to a protection structure for protecting a lower portion of an internal combustion engine in a motorcycle in which an internal combustion engine and a power transmission case portion thereof are integrated and a power unit holding a drive wheel at a rear portion of the power transmission case portion.

  2. Description of the Related Art Conventionally, a structure for protecting a lower portion of an internal combustion engine has been proposed in a motorcycle in which an internal combustion engine and a power transmission case portion thereof are integrated and a power unit holding a drive wheel at a rear portion of the power transmission case portion. .

  For example, Patent Document 1 below shows a structure in which a main stand is provided at a lower center portion of an oil pan defined at the lower portion of an internal combustion engine, and the oil pan is protected by a front cover and the main stand. ing.

JP 59-137268 A (FIGS. 1 to 3)

  However, in the structure shown in Patent Document 1, the main stand is pivotally supported at the lower center part of the oil pan, and when protecting the rear of the power unit or when trying to ensure the minimum ground height, The problem remained.

  The present invention solves the above problems and prevents the main stand from projecting downward while covering the power transmission case part at the rear from the oil pan part in a wide and continuous manner, thereby reducing the minimum ground height. It is an object of the present invention to provide a protective structure for a lower part of an internal combustion engine in a motorcycle that can be largely taken.

  In order to solve the above-mentioned problems, the invention according to claim 1 is a motorcycle including a power unit in which an internal combustion engine and a power transmission case portion thereof are integrated and a driving wheel is held at a rear portion of the power transmission case portion. A crankcase bottom wall defining an oil pan portion positioned below the crankshaft of the internal combustion engine, a crankcase rear wall covering the rear of the crankshaft, and a main stand disposed behind the crankcase rear wall A base part of the front end of the main stand is supported by the main stand mounting boss part via a main stand support shaft, and a rear end of the protective plate that covers the oil pan part from below is provided. A protection structure for a lower part of an internal combustion engine in a motorcycle, which is supported by a main stand support shaft.

  According to a second aspect of the present invention, in the protection structure for the lower part of the internal combustion engine in the motorcycle according to the first aspect, the main stand mounting boss portions are provided on the left and right, and the main stand mounting boss on the power transmission case portion side is provided. The part is provided integrally on the lower surface of the power transmission case part.

  According to a third aspect of the present invention, in the protection structure for the lower part of the internal combustion engine in the motorcycle according to the first aspect, the main stand mounting boss portions are provided on the left and right, and the main stand is provided on the left and right main stand mounting bosses. The protective plate may be supported on the main stand support shaft on the outer side of the main plate mounting bosses, covering the lower ends of the left and right main stand mounting bosses.

  According to a fourth aspect of the present invention, in the protective structure for the lower part of the internal combustion engine in the motorcycle according to the first aspect, a hanger portion for supporting the power unit on the vehicle body frame is provided on the front side of the crankcase bottom wall. It is formed to extend forward from the bottom wall.

  According to a fifth aspect of the present invention, in the protective structure for the lower part of the internal combustion engine in the motorcycle according to the fourth aspect, a suspension link portion that connects the hanger portion and the vehicle body frame is located in front of the hanger portion. It is characterized by continuously covering the lower part of the engine.

  According to a sixth aspect of the present invention, in the protective structure for the lower part of the internal combustion engine in the motorcycle according to the fifth aspect, a connecting portion plate is provided at a lower center of the connecting shaft of the connecting portion between the suspension link portion and the hanger portion. It is arrange | positioned so that it may cover.

  According to a seventh aspect of the present invention, in the protective structure for the lower part of the internal combustion engine in the motorcycle according to the first aspect, the protective plate has a front side narrower than the hanger part in the bottom view, and the crank is viewed from the left and right. It is characterized by being fastened to the case bottom wall.

  According to an eighth aspect of the present invention, in the protective structure for the lower part of the internal combustion engine in the motorcycle according to any one of the first to seventh aspects, the protective plate is positioned below a drain bolt of the oil pan portion. Thus, an opening for oil maintenance is provided.

  According to a ninth aspect of the present invention, in the protection structure for the lower part of the internal combustion engine in the motorcycle according to any one of the first to seventh aspects, the main stand extends to a side of the vehicle body of the power transmission case portion. It is characterized by having a bar.

  According to the protection structure for the lower part of the internal combustion engine in the motorcycle of the first aspect of the invention, the main stand support shaft is used as a common support shaft, and the rear end of the protection plate and the base portion of the front end of the main stand are supported. Since the main stand support shaft is supported by the main stand mounting boss part located behind the rear wall of the case, the protective plate and the main stand are wide and continuous from the oil pan part to the rear power transmission case part. It is possible to prevent the main stand from protruding downward and to increase the minimum ground height.

  According to the invention of claim 2, in addition to the effect of the invention of claim 1, the main stand mounting boss part can be disposed more rearward and can be covered widely to the rear.

  According to the invention of claim 3, in addition to the effect of the invention of claim 1, it is arranged in the vehicle width direction on the front side of the main stand mounting boss portion, and covers the lower end portion of the main stand mounting boss portion and is positioned below it. By the protective plate, the main stand mounting boss part and the base part of the main stand can be widely protected from below.

  According to the invention of claim 4, in addition to the effect of the invention of claim 1, a continuous protection structure for the lower part of the internal combustion engine is formed by the hanger portion, the protection plate, and the main stand.

  According to the invention of claim 5, in addition to the effect of the invention of claim 4, the lower part of the internal combustion engine is further covered widely by the connection structure with the vehicle body frame.

  According to the sixth aspect of the invention, in addition to the effect of the fifth aspect of the invention, the structure is such that the lower part of the internal combustion engine is covered more broadly without any level difference, and the protection of the vehicle is increased.

  According to the invention of claim 7, in addition to the effect of the invention of claim 4, the fastening part on the front side of the protective plate is protected by the hanger part to prevent loosening of the fastener.

  According to the invention of claim 8, in addition to the effect of the invention of any of claims 1 to 7, the drain bolt is protected from below, the drain bolt is easily attached and detached, and the drained oil is passed through. Bolt protection by the protection plate and easy maintenance are compatible.

  According to the ninth aspect of the present invention, in addition to the effect of any of the first to seventh aspects, the power transmission case portion is protected by the step bar of the main stand extending to the side of the vehicle body.

1 is an overall left side view of a motorcycle according to an embodiment of the present invention. 1 is a left side view of a power unit of a motorcycle according to the present embodiment, showing a main part of a protective structure for a lower part of an internal combustion engine in the motorcycle of the present embodiment, a main stand, a protection plate, a hanger part of a power unit, and a hanger part. It is explanatory drawing of the relationship with the suspension link part which connects to a vehicle body frame. It is a principal part left view of the power unit of this embodiment, and shows the left side surface of the attachment state of a protective cover. FIG. 4 is a cross-sectional development view of the front half of the power unit of the present embodiment, as indicated by arrows IV-IV in FIG. 3. FIG. 3 is a partial explanatory view showing the arrangement of the main stand, the protection plate, and the like on the bottom surface, showing a part of the bottom of the power unit according to the present embodiment as viewed in the direction of arrow V in FIG. It is a top view of the protection plate of this embodiment. It is a left view of the protection plate of this embodiment shown by the arrow VII-VII in FIG. It is a right view of the protection plate of this embodiment shown by a VIII-VIII arrow in FIG.

  Hereinafter, a protection structure for a lower part of an internal combustion engine in a motorcycle according to an embodiment of the present invention will be described with reference to FIGS.

Note that the directions such as front, rear, left, right, up, down, etc. in the description of the present specification and the claims are based on the direction of the vehicle when the power unit according to the present embodiment is mounted on a vehicle, that is, a motorcycle. In the figure, arrow FR indicates the front of the vehicle, LH indicates the left side of the vehicle, RH indicates the right side of the vehicle, and UP indicates the upper side of the vehicle.
Further, in the figure, the black small arrow schematically shows the flow of cooling air of the V-belt type continuously variable transmission, and the white small arrow schematically shows the flow of cylinder portion cooling air.

  FIG. 1 shows an entire left side surface of a scooter type motorcycle 1 as a motorcycle according to this embodiment. In the motorcycle 1, an internal combustion engine 2 and a power transmission case portion 3 for a rear wheel 6 are integrated and swingably attached to a vehicle body frame 4, and the rear wheel 6 as a drive wheel is connected to the power transmission case. A power unit 5 that pivotally supports the rear part of the part 3 is provided below the body frame 4.

In the motorcycle 1 of the present embodiment, a pair of left and right front forks 41 that pivotally support the front wheel 7 via the front wheel shaft 7a is steered to the head pipe 40 located at the front end of the vehicle body frame 4 via the steering stem 42. It is pivoted as possible.
Further, the front fender 8 supported by the front fork 41 covers the upper part of the front wheel 7, and the periphery of the head pipe 40 is covered with a front cover 9 which is a vehicle body cover configured separately from the front fender 8. .

The front cover 9 is attached to the vehicle body frame 4 side via a head pipe 40, and the front lower portion is adjacent to the upper surface of the front fender 8 and forms a shelf-like extension portion 10 extending upward. ing. A headlight 11 is provided on the front surface and a blinker 12 is provided on the side surface at the front end side of the extending portion 10.
A steering stem 42 rotatably supported by the head pipe 40 extends above the front cover 9 and is covered with the handle cover 13, and a tip end portion extends laterally from the handle cover 13 and is used for steering. Steering handle 14 is provided. In the handle cover 13, an instrument 15 and the like are provided above.

The vehicle body frame 4 is connected to a main frame 43 obliquely descending from the head pipe 40, and branching into a pair of left and right main frames 43A, 43A at the lower portion thereof and extending substantially horizontally rearward. The head pipe 40 and the passenger seat A heel portion 44 is formed in which the ease of straddling is improved with the space between 16 as a low portion.
A step floor 17 is provided on the flange 44 so as to be connected to the lower rear of the front cover 9.

The main frames 43A and 43A form a bent portion 45 at the rear of the step floor 17, extend obliquely upward as a pair of left and right rear main frames 43B and 43B, and then extend substantially horizontally rearward.
On the rear main frames 43B and 43B, an occupant seat 16 and a loading platform 18 are supported.
The left and right main frames 43A and 43A and the rear main frames 43B and 43B are connected to each other by frames in the vehicle width direction.

In addition, the code | symbol 19 in FIG. 1 is an inner fender attached to the power unit 5 and covering the upper part of the rear-wheel 6. FIG. Reference numeral 20 is a rear fender, 21 is a taillight, 22 is a rear blinker, 23 is a rear cushion, 24 is a starter kick arm, 48 is a main stand, and 49 is a side stand.
The side stand 49 is attached to the rear main frame 43B of the motorcycle 1 and is provided on the rear side of the vehicle body. The side stand 49 is located on the outer side of the cooling air duct 80 when not in use.

1 and 2, when not in use, that is, when stored, the main stand 48 is located at the front end and is pivotally supported by the power unit 5, and a stand extending rearward substantially horizontally from the base 48a. A bar 48b and a step bar 48c extending upward from the stand bar 48b are provided.
When not in use, as shown in FIGS. 1 and 2, the stand bar 48 b is flipped up and stopped by a spring device (not shown).
At the time of use, the step bar 48c is stepped down and the stand bar 48b is positioned in the vertical direction, and the motorcycle 1 is held independently with the rear wheel 6 floating.

The power unit 5 is configured by integrating a front internal combustion engine 2 and a power transmission case portion 3 disposed on the left side of the rear wheel 6 on the left side of the rear wheel 6. The internal combustion engine 2 is a single cylinder four-stroke cycle. In the power unit case 50, the crankshaft 51 is oriented in the vehicle width direction of the motorcycle 1.
In addition, the internal combustion engine 2 includes a power unit case 50 and a cylinder block 53 and a cylinder head 54 that are sequentially stacked on the power unit case 50. (See FIG. 4).

  From the internal combustion engine 2 to the rear, a V-belt type continuously variable transmission 30 as a power transmission mechanism provided in the power transmission case portion 3 and located on the left side of the rear wheel 6 and a gear type provided at the rear thereof. And a rear wheel 6 as a drive wheel is pivotally supported by the speed reduction mechanism 31.

  In FIG. 1 and FIG. 2 showing an enlarged main part of the power unit 5 and the like, the power unit 5 is a transmission outer case serving as an outer shell of a transmission chamber 32 (described later) that houses a V-belt continuously variable transmission 30. 56 (see FIG. 3) are shown with cooling air ducts 80 for taking in the cooling air of the V-belt type continuously variable transmission 30 and their outer sides covered with side covers 95 and duct covers 96. (See FIG. 4).

The power unit 5 includes a pair of left and right hangers 55, 55 at the lower front portion of the power unit case 50.
On the other hand, on the rear side of the step floor 17 of the motorcycle 1, a pair of left and right support brackets 46, 46 are joined to the bent portions 45 of the main frames 43A, 43A.
The power unit 5 is supported by the support brackets 46 and 46 of the vehicle body frame 4 so that the power unit 5 can swing up and down via the suspension link portions 47 extending in the vehicle front-rear direction at the hanger portions 55 and 55 at the front lower part.
On the other hand, the rear part of the power transmission case 3 of the power unit 5 supports the rear wheel shaft 6a of the rear wheel 6 and is supported by the rear main frames 43B and 43B via the rear cushion 23 so as to be able to approach and separate.

On the left side of the rear wheel 6, an air cleaner case 26 is supported on the upper part of the power transmission case 3 of the power unit 5, and an intake pipe 27 extending from the upper part of the cylinder head 54 of the internal combustion engine 2 curves backward. To the air cleaner case 26 through the throttle body 28.
Further, an exhaust pipe (not shown) is attached downward from the cylinder head 54, and the exhaust pipe bypasses the right side and is connected to a silencer (not shown) disposed on the right side of the vehicle body.

FIG. 3 is a left side view of the main part of the power unit 5 and the air cleaner case 26 shown in FIGS. 1 and 2. Unlike FIGS. 1 and 2, the cylinder is shown with the side cover 95 and the duct cover 96 removed. The cooling shroud 65 of the part 52, the transmission outer case 56, a part of the cooling air duct 80 and the power unit case 50, and the left side appearance of the air cleaner case 26 are shown.
FIG. 4 is a cross-sectional development view of the front half of the power unit 5 as viewed in the direction of arrows IV-IV shown in FIG. 3, and the cooling air duct 80, the side cover 95, and the duct cover 96 are schematically shown.

  As shown in FIG. 4, the power unit case 50 is configured by combining a left unit case 50L and a right unit case 50R which are divided into left and right parts, and the right unit case 50R is the right half of the crankcase, that is, Make the right crankcase.

The left unit case 50L includes a front left crankcase portion 50La, a central transmission inner case portion 50Lb, and a rear reduction gear case portion 50Lc (see FIGS. 1 to 3).
The front left crankcase portion 50La has an open surface on the right side and is abutted and fastened with the right unit case 50R to constitute the crankcase of the internal combustion engine 2.

At the lower part of the crankcase formed by the left crankcase portion 50La and the right unit case 50R, a crankcase bottom wall 111 that is positioned below the crankshaft 51 and defines an oil pan portion 110, and the rear of the crankshaft 51 A crankcase rear wall 112 is formed to cover (see FIGS. 2 and 3).
That is, the hanger portions 55 and 55 for supporting the power unit 5 on the vehicle body frame 4 are formed so as to extend from the rank case bottom wall 111 formed between the left crankcase portion 50La and the right unit case 50R to the front side thereof. Has been.

The central transmission inner case portion 50Lb has an open surface on the left side, and the open surface is covered with a transmission outer case 56 that forms the shell of the transmission chamber 32. The transmission chamber 32 has a V-belt type inside. The continuously variable transmission 30 is stored.
The rear reduction gear case portion 50Lc has an open surface on the right side, and the open surface is covered with a reduction gear cover (not shown), in which a gear type reduction mechanism 31 (see FIGS. 1 to 3) is housed.
That is, the transmission inner case portion 50 </ b> Lb and the transmission outer case 56, and the reduction gear case portion 50 </ b> Lc and the reduction gear cover serve as the power transmission case portion 3 for the internal combustion engine 2.

A cylindrical portion 91 projecting forward is formed in front of the transmission outer case 56 in which the V-belt type continuously variable transmission 30 is housed, and the front end thereof is a substantially rectangular case opening 92. Yes.
A cooling air duct 80 communicating with the inside of the transmission outer case 56, that is, the inside of the transmission chamber 32, is attached to the case opening 92. The air duct 80 is formed to communicate with the transmission chamber 32.

In addition, a duct cover 96 that covers the outer side of the cooling air duct 80 is fastened to and attached to the transmission outer case 56, and a soundproof material (not shown) is interposed outside the transmission outer case 56. A side cover 95 is attached, and the side cover 95 also covers the fastening portion 96a of the duct cover 96.
1 to 2, the power unit 5 has an appearance on the left side surface to which the side cover 95 and the duct cover 96 are attached.

  In the crankcase having the left crankcase portion 50La and the right unit case 50R as shells, the crankshaft 51 is oriented in the vehicle width direction and is rotatably supported by the left and right main bearings 57, 57. A cylinder portion 52 is provided from the crankshaft 51 toward the front of the vehicle, and a connecting rod 60 connects a piston 59 that reciprocates in a cylinder liner 58 of the cylinder block 53 and a crankpin 51a of the crankshaft 51.

  Among the extending portions of the crankshaft 51 extending in the horizontal direction, an AC generator 61 is provided at the right extending portion, and a cam chain drive sprocket 62 and a V-belt type continuously variable transmission 30 are provided at the left extending portion. Drive pulley 33 is provided.

  The AC generator 61 provided on the right side surface of the right unit case 50R has a hook-shaped outer rotor 61b fixed to the end of the crankshaft 51 protruding from the central cylindrical portion 50Ra of the right unit case 50R via an ACG boss 61a. A magnet 61c is disposed on the inner peripheral surface in the circumferential direction. A stator 61e around which a stator coil 61d is wound is fixed to the central cylindrical portion 50Ra on the inner peripheral side of the magnet 61c.

  A forced air cooling fan 63 is attached to the right side surface of the outer rotor 61b, and a fan cover 64 covers the right side thereof. A cooling shroud 65 that is connected to the fan cover 64 and covers the cylinder portion 52, that is, the periphery of the cylinder block 53 and the cylinder head 54 is provided.

  The fan cover 64 is provided with a cylinder portion cooling air inlet 64 a so as to face the forced cooling fan 63. The cylinder portion cooling air sucked from the cylinder portion cooling air inlet 64a by the forced cooling fan 63 circulates around the cylinder portion 52, that is, the cylinder block 53 and the cylinder head 54 inside the cooling shroud 65, thereby cooling the cylinder portion 52. Thereafter, it is discharged as hot air from a cylinder part cooling air outlet 66 (see FIG. 3) provided on the opposite side of the cylinder part cooling air inlet 64a, that is, on the cooling shroud 65 on the lower left side of the cylinder part 52. The

Of the extending portions of the crankshaft 51 extending in the left-right horizontal direction, the drive pulley 33 is provided in the left extending portion.
The drive pulley 33 at the left end of the crankshaft 51 is composed of a fixed pulley half 33A and a movable pulley half 33B. The fixed pulley half 33A is spline-fitted to the left end of the crankshaft 51 and fixed via a boss 34, and the movable pulley half 33B is pivotally supported by the crankshaft 51 via a boss on the right side thereof. The side pulley half 33B slides in the axial direction and can move toward and away from the fixed pulley half 33A, and the V belt 35 is sandwiched and wound between the pulley halves 34A and 34B.

A cooling fan 93 is provided on the outer surface of the fixed pulley half 33A of the drive pulley 33, and the cooling air is sucked into the transmission chamber 32 as will be described later as the drive pulley 33 rotates. It will be a thing.
A starter driven gear 94 is provided on the outer periphery of the fixed pulley half 33A to transmit the rotational power of the starting motor 69 via the starter pinion gear 68 (see FIG. 3).

A cam plate 37 is provided at a fixed position near the annular seal member 36 on the right side of the movable pulley half 33B, and a slide piece 37a provided at the outer peripheral end of the cam plate 37 is attached to the outer peripheral end of the movable pulley half 33B. It is slidably engaged with a cam plate sliding boss portion 33Ba formed in the direction.
The side surface of the movable pulley half 33B on the cam plate 37 side is tapered toward the cam plate 37 side, and the dry weight roller 37b is accommodated between the cam plate 37 inside the tapered surface.

  Therefore, when the rotational speed of the crankshaft 51 increases, the dry weight roller 37b that rotates between the movable pulley half 33B and the cam plate 37 moves in the centrifugal direction due to centrifugal force, and the movable pulley half 33B becomes dry weight. The roller 37b is pressed to move to the left to approach the fixed pulley half 33A, and the V belt 35 sandwiched between the pulley halves 34A and 34B is moved in the centrifugal direction to increase the winding diameter. It is configured.

As the winding diameter of the drive pulley 33 changes, the winding diameter of the driven pulley 39 (see FIG. 5) on the driven shaft 38 (see FIG. 5) changes in reverse, and a continuously variable transmission rotational speed is performed. However, since the structure of the V-belt type continuously variable transmission 30 is publicly known, detailed description thereof is omitted.
The driven shaft 38 of the V-belt type continuously variable transmission 30 serves as an input shaft for the gear-type reduction mechanism 31, and the output shaft of the reduction mechanism 31 is coupled integrally with the rear wheel shaft 6 a of the rear wheel 6.

  As shown in FIG. 4, the cylinder head 54 fastened to the cylinder block 53 is further fastened to the top surface of the piston 59 on the inner peripheral side of the mating surface 54 a with the cylinder head cover 70 placed on the cylinder head 54. The ceiling wall portion of the combustion chamber 71 protrudes greatly, and bearing walls 72L and 72R that form a pair are formed facing each other.

The bearing walls 72L and 72R protrude larger than the mating surface 54a, and the left and right bearing walls 72L and 72R are provided with a valve operating mechanism 73 composed of a SOHC type valve system.
Since the cylinder head 54 is largely tilted to near horizontal, the left and right bearing walls 72L and 72R protrude forward from the mating surface 54a, and the camshaft 76 is rotatable and oriented in the horizontal direction. A cam chain chamber 74 is formed between the left side wall of the cylinder head 54 and the left bearing wall 72L. A driven sprocket 77 is fitted to the left end portion of the camshaft 76 protruding into the cam chain chamber 74.

On the other hand, a cam chain chamber in which a cam chain 78 is provided between a cam chain drive sprocket 62 fitted to the crankshaft 51 and a driven sprocket 77 and communicates with the left crankcase portion 50La, the cylinder block 53, and the cylinder head 54. As it passes through 74, the rotation of the crankshaft 51 is transmitted to the camshaft 76 at half the rotational speed, and the valve mechanism 73 is driven.
Since the valve operating mechanism 73 itself is a known one, its description is omitted.

  In the cylinder head 54, an ignition plug 79 is inserted obliquely from the opposite side (right side) of the cam chain chamber 74 toward the combustion chamber 71, and the plug cap 79a is attached to the ignition plug 79 so as to protrude obliquely forward. Established.

In the present embodiment, the V-belt type continuously variable transmission 30 is cooled by forcibly flowing cooling air into the transmission chamber 32, and a configuration for incorporating the cooling air is provided at the front portion of the transmission outer case 56. Is provided.
As shown in FIG. 4, the front section of the transmission inner case portion 50 </ b> Lb, the transmission outer case 56, and the cross section of the periphery of the cooling air duct 80 are shown. The left side is formed so as to be covered with a transmission outer case 56.
A cylindrical portion 91 that protrudes forward is formed on the front peripheral wall 56a of the transmission outer case 56, and a substantially rectangular case opening 92 that serves as a cooling air inlet to the transmission chamber 32 is formed at the front end thereof. It is formed.

On the other hand, as shown in FIG. 3, the cooling air duct 80 is fitted in the case opening 92 to form an in-duct cooling air passage 90 </ b> A.
The fitting connection portion 81 as the duct outlet opening projects rearward to form a substantially rectangular opening.

  The cooling air duct 80 is connected to the case opening 92 of the transmission outer case 56 and extends toward the front of the vehicle from the fitting connection 81 with the case opening 92, and then the upstream side is cooled. Bending upward along the side surface of the shroud 65, further bending back and folding back into a U-shape, a cooling air intake 82 that is a duct inlet opening toward the rear of the vehicle is provided.

  Accordingly, since the cooling air duct 80 is disposed along the side surface of the cooling shroud 65 of the cylinder portion 52, the overhang of the power unit 5 to the side of the vehicle body is suppressed, and the cooling air intake port 82 with respect to the rear wheel 6 is suppressed. The distance increases, and the intrusion of dust or the like into the cooling air intake 82 due to the rear wheel 6 being rolled up is reduced.

On the other hand, as shown in FIG. 4, the cylindrical portion 91 of the transmission outer case 56 is located on the side of the cooling fan 93 provided on the outer surface of the fixed pulley half 33 </ b> A of the drive pulley 33 in the transmission chamber 32. Is formed and a cooling air passage 90B for the transmission chamber is formed.
Thus, the cooling air passage 90 (90A, 90B) for guiding the cooling air to the side of the cooling fan 93 in the transmission chamber 32 accommodates the cooling air duct 80 and the V-belt type continuously variable transmission 30. It is formed in communication with the chamber 32.

When the crankshaft 51 is rotated and the cooling fan 93 is rotated, the cooling air is forcibly sucked, and the cooling air from the cooling air intake port 82 is fitted into the cooling air passage 90A in the duct and the fitting connection portion 81 as the duct outlet opening. Then, it passes through the case opening 92 and enters the transmission outer case 56 via the cylindrical portion 91.
As shown in FIG. 4, the cooling air that has entered the transmission outer case 56 is sucked from the suction opening 97a of the guide plate 97 around the rotation center on the side of the cooling fan 93 in the transmission chamber cooling air passage 90B. It is pushed into the transmission chamber 32 by the cooling fan 93.

  The cooling air pushed into the speed change chamber 32 cools the drive pulley 33, the V belt 35, and the driven pulley 39 attached to the driven shaft 38 (only the central axis is shown in FIGS. 3 and 4), and the speed change chamber 32. The rear driven pulley 39 rotates and is swung up above the transmission chamber 32, provided in the left central portion of the transmission outer case 56 (the left central portion of the transmission chamber 32), and at the downstream end thereof, the transmission It passes through a cooling air discharge hole 98 that opens to the outside under the outer case 56, and is discharged out of the speed change chamber 32, that is, out of the power unit 5.

Further, as shown in FIG. 3, two cooling air discharge ports 99 are also provided at the rear end side of the transmission outer case 56, that is, around the driven pulley 39. Promoting emissions.
The cooling air discharge port 99 is covered with a side cover 95 that covers and attaches to the outside of the transmission outer case 56, so that foreign matter can be prevented from entering the transmission chamber 30 from the outside. .

As shown in FIG. 3, a throttle cable clamper 88 is provided on the back surface 83 of the cooling air duct 80.
As shown in FIG. 4, the cooling air duct 80 is disposed at a predetermined distance from the cooling shroud 65, and a throttle cable clamper is installed in a space 89 between the cooling air duct 80 and the cooling shroud 65. 88 is located and the throttle cable 29 is held on it.

As shown in FIG. 2, the throttle cable 29 has a front end side fixed to the vehicle body frame 4 at the front of the vehicle body, and a rear end side of the throttle cable 29 on the power unit 5 that swings relative to the vehicle body frame 4 (see FIG. 1). Fixed to. Therefore, in order to reduce the throttle operation resistance, it is necessary to hold the throttle cable 29 so as to allow appropriate bending.
Therefore, if a throttle cable clamper 88 is attached to the rear face 83 of the cooling air duct 80, the throttle cable 29 is connected to the space 89 (see FIG. 4) on the side of the cooling shroud 65 and the body frame 4 in front of the throttle cable 29 as shown in the figure. Therefore, the power unit 5 can be bent with respect to the swinging of the power unit 5 and can be properly laid out.

As shown in FIG. 3, a crankcase bottom wall 111 that is positioned below the crankshaft 51 and that defines the oil pan portion 110 is formed at the bottom of the crankcase of the power unit 5.
The rear side of the crankcase rear wall 112 covering the rear side of the crankshaft 51 subsequent to the rear side is provided with a transmission inner case portion 50Lb of the left unit case 50L, that is, a lower surface of the power transmission case portion 3 and a right unit case 50R, respectively. Main stand mounting left boss ("power transmission case side""main stand mounting boss" of the present invention) 100L and main stand mounting right boss ("main stand mounting boss" of the present invention) 100R Is provided (see FIG. 5).

As shown in FIG. 5, a main stand support shaft 101 is inserted and supported by the main stand mounting left boss portion 100L and the main stand mounting right boss portion 100R so as to be horizontally oriented in the vehicle width direction.
The base portion 48a of the main stand 48 is swingably supported via a main stand support shaft 101 inside the main stand mounting left boss portion 100L and the main stand mounting right boss portion 100R.
The main stand support shaft 101 has a retaining flange 101a at one end and a retaining pin hole 101b at the other end. By attaching the retaining pin 102, the main stand mounting left boss portion 100L A base portion 48a that is an attachment portion of the main stand 48 is inserted between the stand attachment right boss portion 100R so as not to be detached.

  Therefore, the main stand 48 is not supported below the center of the oil pan 110 as in the prior art, but is attached to the main stand mounting left boss behind the oil pan 110, that is, behind the crankcase rear wall 112. The stand bar 48b supported by the portion 100L and the main stand mounting right boss portion 100R and extending rearward substantially horizontally from the base portion 48a at the front end of the main stand 48 in the accommodated state such as during travel is provided at the rear of the power unit 5. Can be widely covered and protected, and at the same time, the support position behind the oil pan portion 11 prevents the main stand 48 from projecting downward, so that the minimum ground height can be increased. .

As in the motorcycle 1 according to the present embodiment, in the case where the rear portion of the vehicle is provided with the loading platform 18, when the load is loaded, the rear portion of the vehicle becomes heavy, and the main stand 48 is located near the center of the oil pan portion 110 as in the past. When the main stand 48 is used, the front wheel 7 may be lifted when the main stand 48 is used. However, by placing the support position of the main stand 48 rearward, it is easy to avoid such a problem.
Further, when the starter kick arm 24 is provided in the power unit 5, the starter kick arm 24 is located relatively rearward, so that the main stand 48 is erected in the vicinity of the rear for the stability when the starter kick arm 24 is operated. However, the main stand 48 of the present embodiment can be preferably arranged in that respect.

  In particular, the main stand mounting left boss portion 100L is provided integrally with the transmission inner case portion 50Lb of the left unit case 50L, that is, the power transmission case portion 3, so that the main stand mounting left boss portion 100L is disposed further rearward. The power unit 5 can be covered widely to the rear.

Further, in the power unit 5 of the present embodiment, the main stand support shaft 101 is installed relatively rearward, so that the crankcase formed by the front of the bottom of the power unit 5, that is, the left crankcase portion 50La and the right unit case 50R. A protective plate 104 called a skid plate is provided in order to protect the crankcase bottom wall 111 defining the oil pan 110 at the bottom of the bottom.
That is, the bottom of the power unit 5 is protected by the main stand 48 and the protection plate 104.

The protective plate 104 that covers the oil pan 110 from below is supported by the main stand support shaft 101 at the rear end.
FIG. 6 shows a top view of the protective plate 104, which is the reverse of the illustration in FIG. 7 and 8 are a left side view and a right side view, respectively.
As shown in FIGS. 6 to 8, the protective plate 104 has a peripheral edge that is folded at its left rear end and a right positioning hole 105R at its left rear end and right rear end. Two mounting bolt holes 106L are provided on the left side, and one mounting bolt hole 106R is provided on the right side.

  As shown in FIG. 5, the protection plate 104 covers the lower ends 100La and 100Ra of the left and right main stand mounting bosses 100L and 100R, and the front thereof is arranged substantially horizontally in the vehicle width direction. The main stand support shaft 101 is inserted into the left positioning hole 105L between the left boss portion 100L and the retaining flange 101a, and between the main stand mounting right boss portion 100R and the retaining pin 102. The main stand support shaft 101 is inserted through the right positioning hole 105R and supported by the main stand support shaft 101, and at the same time, the protection plate 104 is positioned.

  Accordingly, since the rear end of the protective plate 104 and the base 48a at the front end of the main stand 48 are supported by using the main stand support shaft 101 as a common support shaft, the rear power transmission case 3 is moved from the oil pan 110 to the front and rear. It can be covered and protected over a wide area.

  In particular, the protective plate 104 is disposed substantially horizontally in the vehicle width direction in front of the left and right main stand mounting bosses, covers the lower ends 100La and 100Ra of the left and right main stand mounting bosses 100L and 100R, Since it is supported by the stand support shaft 101, the left and right main stand mounting bosses 100L, 100R are covered by the protection plate 104 that covers the lower ends 100La, 100Ra of the left and right main stand mounting bosses 100L, 100R and is located below the lower ends 100La, 100Ra. Thus, the base 48a, which is the mounting portion on the main stand 48 side, can be widely protected from below.

In the present embodiment, hanger portions 55 and 55 for supporting the power unit 5 on the vehicle body frame 4 are formed on the front side of the crankcase bottom wall 111 so as to extend forward from the crankcase bottom wall 111.
Therefore, a continuous protective structure for the lower part of the internal combustion engine 2 can be formed by the hanger portions 55, 55, the protective plate 104, and the main stand 48 (see FIGS. 1 and 2).

Further, a suspension link portion 47 that connects the hanger portions 55 and 55 and the vehicle body frame 4 continuously covers the lower part of the internal combustion engine 2 in front of the hanger portions 55 and 55 (see FIGS. 1 and 2).
Therefore, the lower part of the internal combustion engine 2 is further widely covered by the suspension link portion 47 that forms a connection structure with the vehicle body frame 4.

In addition, as shown in FIG. 5, the connecting portion plate 47 b is arranged on the connecting shaft 47 a of the connecting portion between the suspension link portion 47 and the hanger portions 55, 55 so as to cover the lower center.
Therefore, it becomes a structure which covers the lower part of the internal combustion engine 2 more widely without a step, and the protection of the vehicle is increased.

Further, the protection plate 104 has a left unit case 50L that forms a crankcase bottom wall portion 111 with mounting bolts 107L and 107R in the mounting holes 106L and 106R, with the front side being narrower than the hanger portions 55 and 55 in the bottom view. Fastened to the right unit case 50R from the left and right.
Therefore, the fastening portion on the front side of the protective plate 104 is protected by the hanger portions 55 and 55, and the mounting bolts 107L and 107R (the “fastener” in the present invention) are prevented from loosening.

As shown in FIGS. 5 and 6, the protective plate 104 is provided with an oil maintenance opening 104a so as to be positioned below the drain bolt 110a of the oil pan portion 110 in the attached state. Yes.
Therefore, the drain bolt 110a is protected from below and the drain bolt 104a can be easily attached and detached, and the drained oil can be passed therethrough, so that both the protection of the bolt by the protection plate 104 and the ease of maintenance can be achieved.

  Further, as shown in FIG. 5, the main stand 48 includes a step bar 48c that extends to the side of the vehicle body of the power transmission case 3, so that the power transmission case 3 is protected by the step bar 48c.

In this embodiment, as shown in FIG. 5 (see also FIGS. 2 and 4), the brake tube clamper that holds the rear wheel brake tube 6b for the rear wheel 6 at the bottom of the left unit case 50L. 108 is attached, and the rear wheel brake tube 6b is held by two clamp portions 108a.
The brake clamper 108 is provided with a pad portion 108b extending outward (to the left) of the vehicle body between the two clamp portions 108a.

  As shown in FIG. 5 (see also FIG. 3), the pad portion 108b is disposed so as to face the lower side of the opening 98a of the cooling air discharge hole 98 that opens below the transmission outer case 56, Foreign matter from below such as the road surface is prevented from entering the cooling air discharge hole 98.

  Although one embodiment of the present invention has been described above, the aspect of the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention includes those implemented in various aspects within the scope of the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Internal combustion engine, 3 ... Power transmission case part, 4 ... Body frame, 5 ... Power unit, 6 ... Rear wheel (drive wheel), 6b ... Rear-wheel brake tube, 7 ... Front wheel, 18 ... Loading platform, 28 ... Throttle body, 29 ... Throttle cable, 30 ... V belt type continuously variable transmission, 31 ... Deceleration mechanism, 32 ... Shifting chamber, 43 ... Main frame, 43A ... A pair of left and right main frames, 43B ... A pair of left and right rear mains Frame, 46 ... support bracket, 47 ... suspension link, 47a ... connecting shaft, 47b ... connecting plate, 48 ... main stand, 48a ... base, 48b ... stand bar, 48c ... step bar, 50 ... power unit case, 50L ... Left unit case, 50La ... left crankcase part, 50Lb ... transmission inner case part, 50Lc ... reduction gear case part, 50R ... right unit case, 51 ... crankshaft, 52 ... cylinder part, 55 ... hand Gur part, 56 ... Transmission outer case 80 ... Cooling air duct, 88 ... Throttle cable clamper, 95 ... Side cover, 96 ... Duct cover, 98 ... Cooling air discharge hole, 98a ... Opening, 100L ... Main stand left Boss portion, 100La ... lower end portion, 100R ... main stand mounting right boss portion, 100Ra ... lower end portion, 101 ... main stand support shaft, 104 ... protective plate, 104a ... opening, 105L ... left positioning hole, 105R ... right positioning hole, 106L ... Mounting bolt hole, 106R ... Mounting bolt hole, 107L ... Mounting bolt, 107R ... Mounting bolt, 108 ... Brake tube clamper, 108b ... Pad part, 110 ... Oil pan part, 110a ... Drain bolt, 111 ... Bottom of crankcase Wall, 112 ... Crankcase rear wall

Claims (9)

A motorcycle (1) having an internal combustion engine (2) and a power transmission case (3) integrated with each other and having a power unit (5) holding a drive wheel (6) at the rear of the power transmission case (3). In
A crankcase bottom wall (111) positioned below the crankshaft (51) of the internal combustion engine (2) and defining an oil pan portion (110), and a crankcase rear wall (112) covering the rear of the crankshaft (51) ) And a main stand mounting boss portion (100L, 100R) disposed rearward from the rear wall (112) of the crankcase,
The base (48a) at the front end of the main stand (48) is supported by the main stand mounting boss (100L, 100R) via the main stand support shaft (101), and the oil pan (110) is moved downward. A protective structure for a lower part of an internal combustion engine in a motorcycle, characterized in that a rear end of a protective plate (104) that covers the vehicle is supported by the main stand support shaft (101).   The main stand mounting bosses (100L, 100R) are provided on the left and right, of which the main stand mounting boss (100L) on the power transmission case (3) side is integrated with the lower surface of the power transmission case (3). The protection structure for the lower part of the internal combustion engine in the motorcycle according to claim 1, wherein the protection structure is provided.   The main stand mounting bosses (100L, 100R) are provided on the left and right, the main stand (48) is inside the left and right main stand mounting bosses (100L, 100R), and the protective plate (104) is The left and right main stand mounting bosses (100L, 100R) are covered by the main stand support shaft (101) outside and covering the lower ends (100La, 100Ra). A protective structure for the lower part of an internal combustion engine in a motorcycle.   On the front side of the crankcase bottom wall (111), hangers (55, 55) for supporting the power unit (5) on the vehicle body frame (4) are formed extending forward from the crankcase bottom wall (111). The protective structure for the lower part of the internal combustion engine in the motorcycle according to claim 1.   A suspension link portion (47) connecting the hanger portion (55, 55) and the vehicle body frame (4) continuously covers the lower part of the internal combustion engine (2) in front of the hanger portion (55, 55). The protective structure for the lower part of the internal combustion engine in the motorcycle according to claim 4.   A connecting portion plate (47b) is disposed on the connecting shaft (47a) of the connecting portion between the suspension link portion (47) and the hanger portion (55, 55) so as to cover the lower center. The protective structure for the lower part of the internal combustion engine in the motorcycle according to claim 5.   The protective plate (104) is fastened to the crankcase bottom wall (111) from the left and right sides with a front side narrower than the hanger part (55, 55) in a bottom view. The protective structure for the lower part of the internal combustion engine in the motorcycle according to claim 4.   An oil maintenance opening (104a) is provided in the protective plate (104) so as to be positioned below a drain bolt (110a) of the oil pan (110). The protection structure for the lower part of the internal combustion engine in the motorcycle according to claim 7.   The motorcycle according to any one of claims 1 to 7, wherein the main stand (48) includes a step bar (48c) extending to a side of a vehicle body of the power transmission case portion (3). Protective structure under the internal combustion engine.

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