JP4135352B2 - Small motorcycle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small motorcycle in which an engine can be mounted in a step-through type vehicle body structure while suppressing the rise of a floor.
[0002]
[Prior art]
In a step-through type motorcycle such as a scooter type vehicle in which a footrest floor is formed substantially flat and can be easily boarded and exited from the left and right, a four-cycle engine is disclosed in Japanese Patent Laid-Open No. 2000-168669. May be installed.
[0003]
[Problems to be solved by the invention]
In the motorcycle described above, since the engine and the auxiliary equipment attached thereto are accommodated in the step portion (floor), there is a problem that an upward protruding portion is generated, and the floor cannot be formed in a nearly flat shape. In such a case, when the occupant puts his or her foot on the step when getting on, this bulge narrows the foot space. In addition, there is a problem that the position of the footrest is obstructed, and the degree of freedom of the riding posture is lowered due to the restriction of the footrest position.
[0004]
On the other hand, it is desirable to make the above-mentioned protruding protrusions as follows.
(1) Arrange the vehicle at the center in the width direction so that the feet can be placed on both sides.
(2) The protruding portion is arranged as far back as possible.
On the other hand, the drive chain should be placed as close to the center of the vehicle body as possible, while ensuring the minimum necessary clearance from the rear tire width in order to reduce the appearance and weight.
As described above, a motorcycle that has been compactly combined with the engine center position and the drive chain line that are separately required has not been proposed.
[0005]
The present invention has been made paying attention to the above-mentioned problems of the prior art, and can reduce the protrusion on the step part at the center of the rear part so that the footrest space can be expanded so as not to interfere with the footrest. The purpose of the present invention is to provide a small motorcycle suitable for town riding with high convenience such as quick getting on and off and ease of use.
[0006]
[Means for Solving the Problems]
  In the present invention, the vehicle body frame is attached to the rear end of the down tube obliquely downward from the steering head pipe and extends rearward substantially horizontally to form the bottom portion, and then forms a bottom portion. With a pair of left and right side frames that stand upward, it has a substantially U shape when viewed from the side.
  The front wheel is pivotally supported by a front fork rotatably provided on the steering head pipe of the vehicle body frame, and the rear wheel is pivotally supported by a rear wheel suspension portion fixed integrally around the bent portion of the side frame,
  Form a flat step floor on the left and right side frames that form the bottom of the body frame between the front and rear wheels,
  A seat seat is fixed to the upper part where the side frame stands, and a fuel tank is disposed below the seat,
  The engine has an engine suspension portion provided in an engine case at least in front of the crankshaft and behind the output shaft,
  A bracket for suspending the engine suspension portion formed at the rear of the output shaft is provided at the bent portion of the side frame, and the rear wheel suspension portion is fixed to the side frame with the bracket of the bent portion being sandwiched up and down,
  Engine caseTheAbove side frameRearSuspended and suspended on the side frame and the back of the step floorThanWhile arranged below,
  Inclining the cylinder of the engine forward and upward and facing between the pair of side frames, arranging an air cleaner between the side frames behind the cylinder and above the engine case, and connecting to the cylinder,
  An engine cover that covers the cylinder and the air cleaner is formed at the rear portion of the step floor between the side frames.
[0007]
  According to the inventor's knowledge, in a small motorcycle mainly intended for city riding, convenience such as quick getting on and off and ease of use is pursued. Therefore, a vehicle with a slightly different appearance from the existing scooter type motorcycle is considered.
  In the present invention, in order to improve ease of getting on and off and to secure a foot space, the down tube extending rearward and obliquely downward from the steering head pipe, and attached to the rear end of the down tube, is substantially horizontally rearward. A vehicle body frame that has a substantially U-shape in side view with a pair of left and right side frames that extend in the vertical direction at the bent portion after extending and forming the bottom portion, and the body frame between the front wheels and the rear wheels is adopted. Flat step floors are formed on the left and right side frames forming the bottom.
  The seat seat was fixed to the upper part where the side frame stood up, and a fuel tank was disposed below the seat. In this way, since the fuel tank is disposed directly under the seat, the step floor can be widened and a large space for the foot can be secured.
  The engine has an engine suspension portion provided in an engine case at least in front of the crankshaft and rearward of the output shaft, and a bracket for suspending the engine suspension portion formed behind the output shaft is bent on the side frame. The rear wheel suspension portion is fixed to the side frame with the bracket of the bent portion being sandwiched up and down. As a result, the engine is suspended from the side frame and suspended, so that the suspension position exists in a plane substantially parallel to the step floor. With this setting, the mounting rigidity of the engine tends to be low, so the engine has a suspension part at least in front of the crankshaft and rearward of the output shaft. The rigidity is improved. And the part (bending part) where a rear-wheel suspension part is fixed to a side frame has remarkably high rigidity.
  Also engine caseTheAbove side frameRearSuspended and suspended on the side frame and the back of the step floorThanWhile being arranged below, the cylinder of the engine is inclined forward and upward so that it faces between the pair of side frames, and an air cleaner is arranged behind the cylinder and between the side frames above the engine case to be connected to the cylinder. At the same time, the engine cover portion covering the cylinder and the air cleaner is formed at the rear portion of the step floor between the side frames, so that the step floor can be prevented from rising. Furthermore, since the engine is arranged close to the rear part of the step floor, the intake system parts arranged above the engine case can be biased rearward. Thereby, it can contribute to expansion of foot space.
[0008]
  In additionIn the present invention, the engine has a primary reduction mechanism that decelerates the driving force of the crankshaft and transmits it to the secondary reduction mechanism for driving the rear wheels, and the primary reduction device is disposed on one side in the vehicle width direction of the engine case. A primary reduction mechanism is housed in a primary reduction gear chamber formed by covering with a cover, and the crankshaft isofThe engine suspension provided in the engine case at the front and the rear of the output shaft is provided to face the inner surface in the vehicle width direction of the bracket provided at the side frame, and the mating surface between the engine case and the primary reduction gear cover It is preferable that they are formed on the same surface. In this case, since the mating surfaces of the engine case and the primary speed reduction mechanism cover are disposed on the inner side of the side frame, the cover has a deep drawing shape, and the rigidity of the cover is increased.
[0009]
  In the present invention, the abovePrimary reduction gear coverIt is preferable to provide a kick lever and its transmission mechanism that constitute the engine starting device. In this way, even if an excessive load is applied to the cover during kicking with the engine starting method being a kick type, the cover can be deep drawn to improve rigidity.
  In the present invention, it is preferable that in the starter, when the kick lever is depressed, the drive gear slides in the direction of the crankshaft and meshes with the driven gear at the end of the crankshaft to rotate the crankshaft. Since the kick drive gear is not always meshed (with a one-way clutch), a large kick reaction force is applied at the moment the gear meshes during kicking. Therefore, the effect of increasing the cover rigidity by deep drawing as described above is great.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view of a small motorcycle applied to an embodiment of the present invention, FIG. 2 is a detailed view of an engine mounted on the motorcycle and its surrounding body frame, and FIG. 3 is taken along line III-III in FIG. FIG. 4 is a perspective view from obliquely upward and rearward with the side frame of the vehicle body frame as the center.
[0013]
The small motorcycle according to the embodiment is a vehicle mainly intended for city riding, and is configured in pursuit of convenience such as quick getting on and off and ease of use, and the existing scooter type motorcycle is The car has a slightly different appearance.
[0014]
As shown in FIG. 1, the small motorcycle has a down tube 12 extending obliquely downward and rearward from the steering head pipe 10, and is attached to the rear end 12a of the down tube and bent rearwardly extending substantially horizontally. A vehicle body frame 18 composed of a pair of left and right side frames 16, 16 standing in a substantially vertical upward direction via a portion 14 is substantially U-shaped in a side view.
[0015]
A front wheel 22 is pivotally supported at a lower end portion of a front fork 20 provided on the steering head pipe 10 of the vehicle body frame 18 so as to be rotatable, and is integrally fixed around the bent portion 14 of the side frame 16. The rear wheel 26 is pivotally supported by the rear wheel suspension 24.
A flat or substantially flat step floor 28 is formed on the vehicle body frame bottom 18a between the front wheels 22 and the rear wheels 26, and an engine case 32 of an engine 30 is suspended and suspended below the rear of the step floor 28. Thirty cylinders 34 are inclined forward and faced between the pair of side frames 16 and 16.
An air cleaner 36 is disposed behind the cylinder 34 and above the engine case 32 to connect the intake passage via the carburetor 36a to the cylinder 34, and covers the intake passage via the cylinder 34, the air cleaner 36 and the carburetor 36a. An engine cover portion 38 is formed between the side frames 16 and 16. The exhaust pipe from the cylinder 34 is connected to a muffler device (not shown).
[0016]
Here, in the small motorcycle according to the embodiment, the front fork 20 and the rear wheel suspension 24 of the front wheel suspension are provided with a cushion unit in consideration of the simplicity of structure, weight reduction, operation centered at low speed, and the like. It is not a rigid type and is suspended. Of course, a cushion unit can be provided from the viewpoint of improving riding comfort and driving performance.
The down tube 12 is configured such that a single pipe material has a substantially backward L-shape in a side view.
[0017]
As shown in detail in FIG. 4, the side frames 16, 16 are provided with two left and right pairs spaced apart from each other, connected and fixed by a bridge member 40 at two locations, and located at the center of the vehicle body. The front ends 16a, 16a are bent toward the inner side in the width direction so as to approach the down tube rear end 12a as the front part of the side frames 16, 16 moves forward, and the left and right side parts of the down tube rear end 12a are in contact with each other, and Welded and fixed. The shape in plan view of the connection state of the down tube 12 and the side frame 16 is approximately Y-shaped or approximately fork-shaped. Further, the side frame 16 extends slightly upward at the upper part of the bent portion 14 and further slightly bends to the horizontal direction toward the rear by the bent portion 42 at the upper portion 16b. Therefore, the side frame 16 has an approximate Z shape (right side view) or an approximate S shape (left side view) when viewed from the side as a whole from the front end portion 16a to the upper portion 16b. In the motorcycle, the seat seat 43a is fixed to the upper portion of the bent portion 42 of the upper portion 16b where the side frames 16 and 16 stand up, and the fuel tank 43b is disposed below the seat 43a. It is a thing.
[0018]
The step floor 28 has a width sufficient for placing both feet on the upper portion of a substantially Y-shaped portion in the vicinity of the connection portion between the lower portion of the down tube 12 and the side frame 16 (a pair of left and right side frames). 16 and the width of 16 or 16). Further, the step floor 28 is formed to have the same width as the leg shield 10a covering the steering head pipe 10 and the down tube 12 in front of the vehicle body, and is continuously connected. Yes. A headlamp 10b is provided in front of the leg shield 10a and in front of the steering head pipe 10.
On the other hand, the rear portion of the step floor 28 is smoothly connected to an engine cover 38 that bulges slightly upward in line with the cylinder 34 and the air cleaner 36.
[0019]
1 and 2, the engine 30 is disposed and suspended so that the cylinder 34 is positioned between the pair of left and right side frames 16 and 16 (overlapping the side frame 16 in a side view). Yes. Specifically, the engine 30 has suspension portions 48 a and 48 b in front of the crankshaft 44 and behind the output shaft 46, respectively. The suspension portions 48 a and 48 b are each integrally extended from the front and rear portions of the engine case 32 in a plate shape, and are provided with bolt holes at the front ends thereof. The part is provided with front and rear suspension parts 48a, 48b, and the right part is provided with a front suspension part 48a. In the side frames 16 and 16, brackets 50 a and 50 a for fastening the front suspension portions 48 a and 48 a with bolts are integrally fixed to the inner side surfaces of the front portions by bolts, and the bent portion 14 is also fixed. A bracket 50b for fastening the rear engine suspension portion 48b with a bolt is integrally fixed to the inner side surface portion by welding. Therefore, the engine suspension portion 48b formed on the upper rear side of the output shaft 46 is connected to and installed in the bent portion 42.
[0020]
On the other hand, the rear wheel suspension part 24 has a generally U-shaped shape with a front opening, and is in contact with the side frames 16 and 16 with the bent part 14 sandwiched between the two front end parts 24a and 24a, and by welding. The side frames 16 and 16 are fixed integrally. The bracket 50b and the engine suspension 48b are connected by being sandwiched between the two front end portions of the rear wheel suspension 24. An axle support bracket 52 of the rear wheel 26 is integrally fixed to the rear end of the rear wheel suspension portion 24 by welding or the like.
The engine suspension portions 48a and 48b are provided to face the inner side surfaces (the brackets 50a and 50b) in the vehicle width direction of the side frames 16 and 16, respectively.
[0021]
  As shown in FIGS. 1 to 3, the engine is arranged so that a crankshaft 44 extends along the vehicle width direction and is suspended from side frames 16, 16. One side of the crankshaft 44 (in the embodiment, A primary reduction mechanism 60 including a sprocket (drive sprocket (gear) 54 and driven sprocket (gear) 56) and a chain 58 is disposed at the left end 44L.
  Then, a portion 32a formed in a bowl shape that opens outward on one side of the engine case 32 is provided.onceCovered with the reducer cover 62 and sealedonceReducer chamber 64 is formed,thisonceThe primary reduction mechanism 60 is accommodated in the reduction gear chamber 64.
  The engine case 32 and the cover are arranged so that the mating surface 66 of the cover 62 and the engine case 32 is located substantially on the same plane as the left engine suspension portions 48a and 48b at the front and rear portions of the primary reduction mechanism 60. 62 is formed.
[0022]
  Also, the cover of the primary reduction mechanism 60(Primary reduction gear cover)62, a kick lever 70 constituting the engine starter 68 and itsTransmissionA mechanism 72 is provided. That is, in the starting device 68, the lever shaft 74, to which the kick lever 70 is detachable and fixed in the rotational direction, is connected to the engine case 32.onceA kick drive gear 74b is axially fixed in a reduction gear chamber 64 of the lever shaft 74 so as to be returned to its original position by a spring 74a.
  In the starting device 68,onceA drive gear 76a that rotates about an axis 76a1 positioned on a virtual extension of the crankshaft 44 in the speed reducer cover 62 and that slides in the axial direction, and is fixed to the crankshaft end 44L facing the drive gear 76a. Driven gear 76b.
  In the starting device 68 having such a configuration, when the kick lever 70 is stepped down, the drive gear 76a slides in the direction of the crankshaft 44 (direction approaching the cylinder 34) and meshes with the driven gear 76b of the crankshaft end 44L. Thus, the crankshaft 44 is started to rotate by transmitting the kicking force applied to the kick lever 70 to the crankshaft 44.
[0023]
  In the engine 30, the crankshaft 44 is disposed along the vehicle width direction, and a generator (alternating current (AC) generator) 78 is provided at both ends (right end) of the crankshaft 44.((Left end) The centrifugal clutch 80 and the centrifugal clutch 80 are arranged separately. The primary reduction mechanism 60 is disposed outside the centrifugal clutch 80 in the vehicle width direction, and the driving force decelerated by the primary reduction mechanism 60 is further reduced. The secondary reduction mechanism 82 is disposed on the inner side in the vehicle width direction of the primary reduction mechanism 60 and behind the centrifugal clutch 80. A connecting rod 86 large end is connected by a crank pin 84 disposed substantially in the center of the crank shaft 44 in the axial direction, and the connecting rod 86 small end moves forward and backward in the cylinder 34 via a piston pin 88a. A piston 88 is connected.
  In FIG. 3, reference numeral 90 is a bearing for supporting the crankshaft 44, and 92 is an oil seal.
  The centrifugal clutch 80 includes an inner shoe 80a fixed to the crankshaft 44 and an outer housing 80b that is rotatable at the end of the crankshaft 44. The outer housing 80b is a cylindrical portion 80c that is in sliding contact with the crankshaft 44. The drive sprocket 54 of the primary reduction mechanism 60 is integrally formed on the outer peripheral surface portion of the outer periphery of the first reduction mechanism 60. A driven gear 76b of the engine starting device 68 is detachably fixed to the end of the crankshaft 44 on the outer side of the cylindrical portion with a bolt.
[0024]
  The primary driven sprocket (example of driven side rotating body) 56 of the primary reduction mechanism 60 and the secondary drive sprocket (example of driving side rotating body) 82 a of the secondary reduction mechanism 82 are placed on the same support shaft (intermediate shaft) 94. The support shaft 94 is rotatably supported by a bearing 94a at the rear portion of the engine case 32, and the drive sprocket 82a of the secondary reduction mechanism 82 is exposed to the outside of the engine case 32.
  The primary speed reduction mechanism 60 includes a primary drive sprocket 54 provided on the crankshaft 44, a primary driven sprocket 56 pivotally supported on the rear portion of the engine case 32, and a primary wound around both the sprockets 54 and 56.TransmissionChain 58.
  The secondary reduction mechanism 82 includes a secondary drive sprocket 82a pivotally supported at the rear of the engine case 32, a secondary driven sprocket 82b pivotally integrated with the rear wheel, and both sprockets 82a, Secondary wound around 82bTransmissionIt consists of a chain 82c (see FIG. 1).
[0025]
  The primary reduction mechanism 60 is a primary reduction mechanism.TransmissionA lever shaft (kick shaft) 74 of the kick lever 70 of the starting device 68 is disposed inside the circulation path of the chain 58, and the kick lever 70 is rotatably supported by the lever shaft 74.
  The engine 30 is a four-stroke engine having an intake valve 96a and an exhaust valve 96b at the top of the cylinder 34, and a valve operating mechanism that drives the intake valve 96a and the exhaust valve 96b between the cylinder 34 and the generator 78. 98 is arranged. In the embodiment, the valve mechanism 98 is configured such that the movement of the lever 98a that moves forward and backward by the rotation of the crankshaft 44 (rotation of the cam on the crankshaft) is caused by the intake valve 96a and the exhaust valve via the swinging movement of the rocker arm 98b. It is of the OHV (overhead valve) type that converts to an opening / closing operation of 96b (in synchronization with the advance / retreat of the piston). As the valve operating mechanism, various other mechanisms such as an OHC (overhead cam) type in which a cam is provided on the cylinder head and a timing chain is used instead of the lever can be used.
[0026]
In the small motorcycle according to this embodiment, in order to improve ease of getting on and off and to secure a foot space, a substantially U-shaped body frame 18 is used when viewed from the side, and the bottom of the U-shaped frame 18 is flat. Floor 28 is formed. Further, by suspending the engine 30 below the step floor 28 and tilting the cylinder 34 forward, the upward rise of the step floor 28 can be suppressed. Furthermore, since the engine 30 is disposed close to the rear portion of the step floor 28, intake system components such as the air cleaner 36 and the carburetor 36a disposed above the engine case 32 can be biased rearward. It can contribute to the expansion of the foot space.
[0027]
In the embodiment, as shown in FIGS. 1 and 2, an engine suspension portion 48b formed at the rear of the secondary drive sprocket 82a (output shaft) is bolted to the bent portion 14, and The rear wheel suspension portion 24 is fixed to the side frame 16 with the bent portion 14 interposed therebetween, so that the engine 30 is suspended from the side frames 16 and 16 so that the suspension position is a plane substantially parallel to the step floor 28. Exists within. With this setting, the mounting rigidity of the engine 30 tends to be low. Therefore, the engine 30 is assumed to have suspension portions 48a and 48b at least in front of the crankshaft 44 and rearward of the output shaft 46. By increasing the length, the mounting rigidity is improved. And the part (bending part 14) where the rear-wheel suspension part 24 is fixed to the side frames 16 and 16 has remarkably high rigidity because the rear-wheel suspension part 24 acts as a reinforcing member.
[0028]
  As shown in FIG. 2, the engine suspension portions 48 a and 48 b are provided to face the inner side surfaces in the vehicle width direction of the side frames 16 and 16, and at the front and rear portions of the primary reduction mechanism 60.Primary reduction gear coverThe engine case 32 is formed so as to be positioned substantially on the same surface as the mating surface 66 with the 62. Therefore, the engine case 32 andPrimary reduction gear coverSince the mating surface 66 with 62 is disposed on the inner side of the side frames 16, 16, the cover 62 has a deep drawing shape, and the rigidity of the cover 62 is increased.
  Also, abovePrimary reduction gear cover62, a kick lever 70 constituting the engine starter 68 and itsTransmissionSince the mechanism 72 is provided, the engine starting method is a kick type, and an excessive load is applied to the cover 62 when kicking, so that the cover 62 can be deeply drawn to improve rigidity.
  Further, when the starter 68 depresses the kick lever 70, the drive gear 76a slides in the direction of the crankshaft 44 and meshes with the driven gear 76b at the end 44L of the crankshaft 44 to rotate the crankshaft 44. Since the side drive gear 76a is not always engaged (with a one-way clutch), a large kick reaction force is applied at the moment when the gear is engaged during kicking. Therefore, the effect of increasing the cover rigidity by deep drawing as described above is great.
[0029]
Further, the engine 30 has a crankshaft 44 disposed along the vehicle width direction, and a generator 78 and a centrifugal clutch 80 are arranged at both ends of the crankshaft 44 so that the vehicle of the centrifugal clutch 80 is arranged. A primary speed reduction mechanism 60 is disposed on the outer side in the width direction, and a secondary speed reduction mechanism 82 for further reducing the driving force decelerated by the primary speed reduction mechanism 60 is provided on the inner side in the vehicle width direction of the primary speed reduction mechanism 60 and behind the centrifugal clutch 80. It is arranged to make it compact.
[0030]
  If the driving force transmission mechanism from the crankshaft 44 to the rear wheel 26 is a two-stage chain 58, 82c, an intermediate shaft (primary driven shaft and secondary drive shaft) must be provided in the engine case. . In this case, if the secondary side gear is disposed outward from the primary side gear, the distance between the secondary side chain and the engine center is widened. In this layout, if the secondary side chain is disposed immediately next to the rear wheel, the engine center is offset from the vehicle body center (the vehicle body center exists between the engine center and the secondary side chain). So, in plan viewPrimary reduction mechanismInward than 60 (drive sprocket 54, chain 58, driven sprocket 56)Secondary reduction mechanism82 (drive sprocket 82a, chain 82c, driven sprocket 82b) are arranged. Note that the situation is the same even when other types of driving force transmission mechanisms such as belt hooks and gear drives are used for the speed reduction mechanism.TransmissionIs preferably adopted.
[0031]
  Further, the driven sprocket 56 of the primary reduction mechanism 60 and the drive sprocket 82a of the secondary reduction mechanism 82 are fixed on the same support shaft 94, and the support shaft 94 is supported on the rear part of the engine case 32, so that the secondary Since the drive sprocket 82b of the speed reduction mechanism 82 is exposed outside the engine case 32,Primary reduction mechanism60 can be accommodated and sealed in the engine case 32 and is not exposed to dust or muddy water. Therefore, the frequency of maintenance can be reduced (can be made almost unnecessary).
  The primary reduction mechanism 60 includes a primary drive sprocket 54 provided on the crankshaft 44, a primary driven sprocket 56 pivotally supported on the rear portion of the engine case 32, and a primary wound around both the sprockets 54 and 56.TransmissionSince it comprises the chain 58, both the number of parts and the weight can be reduced as compared with the gear drive. In addition, generation of rattling noise can be suppressed, and the necessity of lubrication is low.
  The secondary reduction mechanism 82 includes a secondary drive sprocket 82a pivotally supported at the rear portion of the engine case 32, a secondary driven sprocket 82b pivotally supported integrally with the rear wheel 26, and both the sprockets 82a. , 82b wound around 82bTransmissionSince it comprises the chain 82c, both the number of parts and the weight can be reduced as compared with the gear drive. In addition, generation of rattling noise can be suppressed, and the necessity of lubrication is low.
  Also, abovePrimary reduction mechanism60 is primaryTransmissionSince the lever shaft 74 of the starting device is disposed inside the circulation path of the chain 58 and the kick lever 70 is rotatably supported by the lever shaft 74, the primary shaft in the engine case 32 is provided.TransmissionSince the mechanism is the chain 58, the lever shaft 74 can be arranged on a straight line connecting the crankshaft and the intermediate shaft. Therefore, the engine case can be reduced in size.
[0032]
The engine 30 is a four-stroke engine having an intake valve 96a and an exhaust valve 96b, and a valve operating mechanism 98 for driving the intake valve 96a and the exhaust valve 96b is disposed between the cylinder 34 and the generator 78. In order to match the center of the engine 30 and the center of the vehicle body, a valve operating mechanism 98 for driving the intake valve 96a and the exhaust valve 96b is disposed between the cylinder 34 and the generator 78. When the valve operating mechanism is arranged between the cylinder and the clutch, the distance between the secondary chain and the center in the engine width direction becomes wide and the center lines cannot be matched but can be matched by the above configuration.
Further, the seat seat 43a is fixed to the upper portion 16b where the side frame 16 stands up, and the fuel tank 43b is disposed immediately below the seat 43a. A large foot space can be secured.
[0033]
【The invention's effect】
  As explained above, according to the present invention, the protrusion of the step floor isrear endSmall in the centerTo beIn addition, it is possible to provide a small motorcycle that can widen the footrest space so as not to interfere with footrest, and is suitable for town riding with high convenience such as quick getting on and off and ease of use.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a small motorcycle applied to an embodiment of the present invention.
FIG. 2 is a detailed view of an engine mounted on the small motorcycle and a surrounding body frame.
FIG. 3 is an explanatory view of an engine cross section taken along line III-III in FIG. 2;
FIG. 4 is a perspective view from obliquely upward and rearward with the side frame of the body frame as the center.
[Explanation of symbols]
10 Steering head pipe
12 Down tube
14 Folding part
16 Side frame
18 body frame
18a Frame bottom
20 Front fork
22 Front wheel
24 Rear wheel suspension
26 Rear wheel
28 step floor
30 engine
32 Engine case
34 cylinders
36 Air Cleaner
38 Engine cover
40 Bridge member
43a Seat seat
60 Primary reduction mechanism
62 Reducer cover
68 Engine starter
70 kick lever
72 Transmission mechanism
80 Centrifugal clutch
82 Secondary reduction mechanism

Claims (4)

A body frame is attached to the rear end of the down tube obliquely downward from the steering head pipe and extends rearward substantially horizontally to form a bottom portion, and then stands up substantially vertically upward at the bent portion. With the left and right pair of side frames, it has a substantially U shape in side view,
The front wheel is pivotally supported by a front fork rotatably provided on the steering head pipe of the vehicle body frame, and the rear wheel is pivotally supported by a rear wheel suspension portion fixed integrally around the bent portion of the side frame,
Form a flat step floor on the left and right side frames that form the bottom of the body frame between the front and rear wheels,
A seat seat is fixed to the upper part where the side frame stands, and a fuel tank is disposed below the seat,
The engine has an engine suspension portion provided in an engine case at least in front of the crankshaft and behind the output shaft,
A bracket for suspending the engine suspension portion formed at the rear of the output shaft is provided at the bent portion of the side frame, and the rear wheel suspension portion is fixed to the side frame with the bracket of the bent portion being sandwiched up and down,
While disposed below the rear portion of the side frame and the step floor engine case and suspended hanging at the rear of the side frames,
Inclining the cylinder of the engine forward and upward and facing between the pair of side frames, arranging an air cleaner between the side frames behind the cylinder and above the engine case, and connecting to the cylinder,
A small motorcycle, wherein an engine cover for covering the cylinder and the air cleaner is formed at the rear portion of the step floor between the side frames. The engine has a primary reduction mechanism that decelerates the driving force of the crankshaft and transmits it to the secondary reduction mechanism for driving the rear wheels, and is formed by covering one side in the vehicle width direction of the engine case with a primary reduction gear cover. The primary reduction mechanism is housed in the primary reduction gear chamber,
Engine suspension portion provided on the rear of the engine case of the forward and the output shaft of the crankshaft is provided with to face the vehicle width direction inner side of the bracket provided in the side frame, and the engine casing and the primary reduction gear cover The small motorcycle according to claim 1 , wherein the small motorcycle is formed on the same plane as the mating surfaces. 3. The small motorcycle according to claim 2 , wherein the primary speed reducer cover is provided with a kick lever that constitutes an engine starting device and a transmission mechanism thereof. 4. The small automatic according to claim 3 , wherein when the kick lever is depressed, the drive gear slides in the direction of the crankshaft and meshes with a driven gear at the end of the crankshaft to rotate the crankshaft. Motorcycle.

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