Scooter type motorcycle

Abstract: A scooter type motorcycle is provided for improving a high speed travelling property by forming a rear wheel supporting member, being a separate body from an internal combustion engine, in a freely swingable manner, for realizing efficient arrangement of parts, and for securing large spaces for floors. In a scooter type motorcycle having lower deck type floors 64a, the scooter type motorcycle includes an internal combustion engine 20 arranged in the rearward of the floors 64a and on a downward side of a seat 66, and a rear wheel 44 supported via a supporting member which is swingable independent of the internal combustion engine 20.

Description: This invention relates to a scooter type motorcycle having low deck type floors. Generally, a unit swing type internal combustion engine is adopted as a scooter type motorcycle, an internal combustion engine unit integrally having a transmission is supported a base end thereof to a car body via links, a rear wheel is pivotally supported at a rear end of the vertically freely swingable engine unit, and a cushion is interposed between the rear end thereof and the car body. Further, in a scooter type motorcycle, there is an example (Japanese Examined Patent Publication No. H1-39397) wherein a transmission case, being a separate body from an internal combustion engine, is supported in a freely swingable manner together with a rear wheel which is pivotally supported at a rear end of the transmission case. In the scooter type motorcycle described in the Examined Japanese Patent, the transmission case is pivotally supported in a freely swingable manner around an output shaft locating more rearward from a crank shaf t of the internal combustion engine that is provided extending to between left and right floor portions. In a motorcycle mounting a former unit swing type internal combustion engine, there has been a limit in a high speed traveling property since weight under the cushion has been heavy. Further, since an entire internal combustion engine is swingable with respect to a car body, a space on a periphery of the internal combustion engine must be secured large for fear of interference thereof with the other parts, so that efficient arrangement of parts has been difficult. In a latter example described in the Examined Japanese Patent, since the transmission case supporting the rear wheel is swingable around the output shaft locating more rearward than that of the crank shaft, a wheel base has been large in length. Further, since the internal combustion engine is provided extending to between the left and right floor portions, it has been impossible to secure spaces for the floor portions wide, and also it has been difficult to obtain a space to arrange accessories between the left and right floor portions. DE-C-962 578 and DE-C-967 035 show a motorcycle in accordance with the preamble of claim 1. There, the front ends of a bifurcted rear swing arm are pivotally near the engine on vehicle frame brackets. EP-A-0 755 852 discloses an integral unit of an engine and a single side rear swing arm housing and a belt-type transmission, which unit is pivotally mounted at the vehicle frame. In view of the foregoing circumstance, the present invention has tried to solve the problems and it is an object of the invention to provide a scooter type motorcycle which is capable of improving a high speed traveling property thereof while a rear wheel supporting member being a separate body from the internal combustion engine, is made freely swingable, which is capable of arranging the parts in a efficient manner, and which is capable of securing the spaces of the floors wide. In order to achieve the object described above, the present invention provides a scooter type motorcycle having a lower deck type floor comprising an internal combustion engine arranged in the rearward of said floor and a downward side of a seat; a rear wheel supported via a supporting member swingable independent of said internal combustion engine, said supporting member includes a left fork portion having a front end and a right fork portion having a front end, characterized in that said supporting member includes a belt type automatic transmission and is pivotally supported coaxially with a crank shaft of said internal combustion engine and said left and right fork portions being supported on both sides of a crankcase of the internal combustion engine. Since the rear wheel is supported via the supporting member which is swingable and independent of the internal combustion engine, weight of a swingable section is made to be light, thus improvement of the high speed traveling property of the motorcycle can be realized, and also arrangement of the parts thereof can be made in an efficient manner on the reason that size of the swingable section is small, thus there is no need to secure the space large enough on the periphery thereof. Additionally, since the internal combustion engine is arranged in the rearward of the floors, spaces for the floors can be secured wide and also the space for disposing accessories or the like can be provided on the floor portions. Since the supporting member supporting a rear wheel is pivotally supported coaxial with the crank shaft of the internal combustion engine, a wheel base can be contracted in length, thus simultaneously a suitable space for disposing accessories and spaces for the floors can easily be secured on a forward side of the internal combustion engine. Preferably, cylinders of the internal combustion engine are tilted forward and a space for disposing accessories or articles is provided on a forward side of the forward tilted cylinders. By tilting the cylinders forward, a seat above the cylinders can be set low, therefore a riding position can be secured in a very relaxing manner. Since the space for disposing the accessories or the articles is provided on a forward side of the internal combustion engine, it is made possible to arrange parts in a good efficient manner. Preferably, a passenger's seat is provided to rearward of a rider's seat at one stage high level, a helmet containing box is arranged on the downward side of the passenger's seat, and an air cleaner is arranged along a bottom face of the helmet containing box. Since the passenger's seat is provided in the rearward of the rider's seat at one stage high level, the helmet containing box is arranged on the downward side of the occupant seat, and the air cleaner is arranged along the bottom face of the helmet containing box, the helmet containing box with a large space and the air cleaner can be arranged in good space efficient manners. Hereinafter, embodiments of the present invention will be described in detail with reference to Fig. 1 through Fig. 6. Fig. 1 shows a side elevation view illustrating an entire body of a scooter type motorcycle according to an embodiment of the present invention; Fig. 2 shows a partly omitted plan view of Fig. 1; Fig. 3 shows an enlarged plan view illustrating essential portions of Fig. 1; Fig. 4 shows a cross sectional view typically illustrating parts taken on line IV-IV of Fig. 1; Fig. 5 shows a side elevation view illustrating an entire body of a scooter type motorcycle according to another embodiment of the present invention; and Fig. 6 shows a side elevation view illustrating an entire body of a scooter type motorcycle according to still another embodiment which is not covered by the claims and is shown for comparison. Fig. 1 shows a side elevation view illustrating an entire scooter type motorcycle 1 according to the present embodiment and Fig. 2 shows a plan view illustrating parts being partly omitted thereof. In a car body frame, a pair of left and right main pipes 3, 3 are extended on oblique downward side from an upper portion of a head pipe 2 to compose front side inclination portions 3a, 3a, are bent rearward at bottom ends of the front side inclination portions 3a, 3a to form central parallel portions 3b, 3b, are bent somewhat oblique upward to compose rear side inclination portions 3c, 3c, and are bent in a horizontal direction to reach to rear side horizontal portions 3d, 3d. A pair of left and right down pipes 4, 4 are laterally widened and extended downward from a lower portion of the head pipe 2 to compose front side vertical portions 4a, 4a, are bent rearward at bottom ends thereof 4a, 4a to form central horizontal portions 4b, 4b, the central horizontal portions are extended substantially in parallel on a lower sides of the central horizontal portion 3b, 3b of the main pipes 3, 3, are bent upward at rear ends thereof 4b, 4b to compose rear side inclination portions 4c, 4c, upper ends thereof 4c, 4c are respectively coupled to rear ends of the central horizontal portions 3b, 3b of the main pipes 3, 3. Approximately three pieces of coupling pipe 5 are interposed between the main pipe 3 and the down pipe 4. A steering shaft 11 is pivotally supported by the head pipe 2, handles 12and 12 are developed and formed in left and right directions upward from the steering shaft, front forks 13 are extended downward from the steering shaft, and a front wheel 14 is pivotally supported at bottom ends of the forks 13. Supporting brackets 3e, 3f are protrusively provided respectively at the central horizontal portion 3b and the rear side inclination portion 3c of the main pipe 3, a supporting bracket 4e is protrusively provided at a rear end of the central horizontal portion 4b of the down pipe 4, and a supporting bracket 4f having long size is also protrusively provided rearward from a lower portion of the rear side inclination portion 4c. An internal combustion engine 20 is suspended by respective four pieces of the supporting brackets 3e, 3f, 4e and 4f described above, on each left and right sides. The internal combustion engine 20 is a four cycle two cylinder internal combustion engine and the internal combustion engine 20 is suspended by the car body frame in such a manner that a crank case 21 is positioned rearward from the rear side inclination portion 4c of the down pipe 4, forward tilted cylinders 22 are inserted and postured between the rear side inclination portions 4c, 4c on both left and right sides and between the central horizontal portions 3b, 3b of the main pipes 3 on both left and right sides, and mount brackets and the like protrusively provided at specified positions of the engine 20 are respectively supported by the supporting brackets 3e, 3f, 4e and 4f via spindles 6, 7, 8 and 9. A belt type automatic transmission 30 is extended rearward by being pivotally mounted a front portion thereof on the crank case 21 of this internal combustion engine 20. An outer rotor 27a of an AC generator 27 are fittingly mounted on a right end of a crank shaft 23 directed in a lateral horizontal direction inside the crank case 21 as illustrated in Fig. 2 and Fig. 3, a cover case 24 covers in the side direction of the outer rotor 27a, and an inner stator 27b of the AC generator 27 is supported by the cover case 24. A rotary shaft 26 is protrusively provided rightward in an opening portion coaxial with the crank shaft 23 of this cover case 24 via a bearing 25 and a front end portion 31a of a right side transmission case 31 of the belt type automatic transmission 30 is fittingly mounted on the protrusively provided portion (refer to Fig. 3). The right side transmission case 31 is extended a fork portion 31c thereof rearward via a coupling portion 31b wraparound to inner side parallel with a.back face of the crank case 21 from the front end portion 31a. On the other hand, a left end of the crank shaft 23 is projected leftward by piercing through the crank case 21 and a drive pulley 33 having a centrifugal transmission mechanism at this projecting portion is installed. An annular supporting member 28 is secured at a circumference of the crank case 21 on an outer side face of the crank case 21 through which the crank shaft 23 pierces and a front end portion 32a of a left side transmission case 32 is supported in a freely swingable manner on the annular supporting member 28 via a bearing 29. The left side transmission case 32 has a coupling portion 32b wraparound to inner side parallel with the back face of the crank case 21 from the front end portion 32a and a fork portion 32c extended rearward. The left side and right side coupling portions 31b and 32b which are wraparound along the back face of the crank case 21, are mutually coupled by coming into contact with each other, the left and right side transmission cases 31 and 32 are integrally united with each other, and the left and right side fork portions 31c and 32c are supported in a vertically freely swingable manner around the crank shaft 23. In a rear portion of the fork portion 32c of the left side transmission case 32, there are provided with a transmission chamber, a driven shaft 34 which is supported in a freely rotatable manner, and a driven pulley 35 which is pivotally supported on the driven shaft 34 via a centrifugal clutch 37. The belt type automatic transmission mechanism is constituted by suspending a V belt 36 between this driven pulley 35 and the drive pulley 33. Inside the transmission chamber of the rear portion of the fork portion 32c, a reduction gear mechanism is constituted in such a manner that a small diametrical gear 38 of a right end of the driven shaft 34 is engaged with a large diametrical gear 40 on an intermediate shaft 39 and a small diametrical gear 41 of the intermediate shaft 39 is engaged with a large diametrical gear 43 of an axle 42. The axle 42 is installed between the left and right side fork portions 31c and 32c, and a rear wheel 44 is supported on the axle 42 between the fork portions 31c and 32c. Accordingly, the left and right side transmission cases 31 and 32 supporting the belt type transmission 30 pivotally support the fork portions 31c and 32c together with the rear wheel 44 in the vertically swingable manner around the crank shaft 23. A rear cushion 45 is interposed between a rear end of the left side transmission case 32 and a rear end of the main pipe 3 Intake pipes 51, 51 extended respectively upward from a left and right side cylinders 22, 22, are bent rearward and are connected with carburetors 52, 52 disposed to be laterally arranged side by side on the crank case 21, and the carburetors 52, 52 are coupled on to an air cleaner 53 disposed in the rearward thereof 52, 52. The air cleaner 53 is arranged between the rear side inclination portions 3c, 3c of the left and right side main pipes 3, 3 or below them and a helmet containing box 54 is installed and supported above the air cleaner 53 and between the rear side horizontal portions 3d, 3d. The air cleaner 53 has top face thereof with a shape bent along a front side bottom face of the helmet containing box 54 and both of the cleaner and the box are fitted together, therefore the large-sized and bulky helmet containing box 54 and the air cleaner 53 are arranged in a good space efficient manner. Exhaust pipes 55, 55 are respectively extended downward from the cylinders 22, 22 further extended rearward after are wraparound to a lower side of the crank case 21, are joined into one piece, is erected and raised after coming out to a right side face of the car body, and is coupled onto a muffler 56 supported on a right side of the rear wheel 44. Further, a main stand 59 is mounted on a bottom end of the crank case 21 in a freely erectable or prostratable manner. A fuel tank 57 is installed and supported on the forward side of the cylinders 22, 22 surrounded by four pieces of pipe such as the central horizontal portions 3b, 3b of the main pipe 3, 3 on an upper side and the central horizontal portions 4b, 4b of the down pipes 4, 4. A radiator 58 is installed between the front side vertical portions 4a, 4a of the down pipe 4, 4. The forward portion of the head pipe 2 is covered with a front cover 61, on both the left and right downward sides of the front cover 61 are covered with leg shields 62, the front side inclination portions 3a, 3a and the central horizontal portions 3b, 3b of the main pipes 3, 3 are covered with a floor tunnel cover 63 in a shape of a channel from upward side, and floor covers 64, 64, having floor steps 64a, 64a extended horizontally in left and right sideward direction from left and right lower end edges of the floor tunnel cover 63 cover the central horizontal portions 4b, 4b of the down pipes 4, 4 from outside (refer to Fig. 4). A rear side upper portion of the front tunnel cover 63 is opened largely in a shape of U, the cylinders 22 and the carburetors 52 are faced to the large opening portion and a rear cover 65 connected to a rear end edge of the floor tunnel cover 63 covers from sideward direction of the rear side inclination portions 3c, 3c and rear side horizontal portions 3d, 3d of the main pipes 3, 3. Further, a rider's seat 66 covers the opening in the shape of U at a rear side upper portion of the floor tunnel cover 63 in a freely openable or closable manner while a front end thereof is pivotally supported and a passenger's seat 67 covers an upper portion opening of the rear cover 65 in a freely openable or closable manner while a rear end thereof is pivotally supported. Accordingly, the rider's seat 66 covers the cylinders 22 and carburetor 52 from above and the passenger's seat 67 covers an opening of the helmet containing box 54 from above. In the internal combustion engine 20 suspended by the car body frame, since the cylinders are tilted forward, the rider's seat 66 covering on the upward side of the engine 20 can be arranged low, a riding position in a relaxed manner can be secured. Further, since the passenger's seat 67 is provided in the rearward of the rider's seat 66 and at one stage high level, the helmet containing box 54 can be arranged on the downward side of the passenger's seat 67, and also since the air cleaner 53 is arranged along the bottom face of the containing box 54, the large-sized helmet containing box 54 and the air cleaner 53 can be arranged in a good space efficient manner. Since the internal combustion engine 20 is located more rearward from foot rest floor portions 64b, 64b of the floor steps 64a, 64a, spaces for floors can be secured wide without being hindered by the internal combustion engine 20. Further, a large space can be secured on a front side of the internal combustion engine 20, large-sized accessories such as a fuel tank 57 can be arranged. Since the belt type transmission 30 is supported in a freely swingable manner separately from and independent of the internal combustion engine 20 suspended from the car body frame by pivotally supporting the rear wheel 44 at a rear end thereof, a swingable section supported by the rear cushion 45 can be remarkably lightening weight thereof in such an extent that the internal combustion engine 20 is not integrated, thus a high speed traveling property as the scooter type motorcycle 1 can be improved Incidentally, the motorcycle conventionally having more or less 140 km/h in its maximum speed range can be enhanced up to approximately 160 km/h in the maximum speed range. Since the transmission cases 31 and 32 pivotally supporting the rear wheel 44 are pivotally supported on the crank case 21 being coaxial with the crank shaft 23, a wheel base can be contracted in length and simultaneously an appropriate space for disposing of parts and spaces for the floors are facilitated to be secured on the front side of the internal combustion engine 20. Subsequently, another embodiment of a scooter type motorcycle 70 in which a structure of a rear portion of a car body is changed will be illustrated in Fig. 5. Meanwhile, the same signal will be employed for the same member as the embodiment described above. In the present scooter type motorcycle 70, a helmet containing box 72 is formed at a rear portion of a rear cover 71 and an opening facing in the rearward of the helmet containing box 72 is closed by a cover member 73 in a freely openable and closable manner. A passenger's seat 74 is provided between this helmet containing box 72 and a rider's seat 66 in a freely openable and closable manner and a fuel tank 75 is disposed on a downward side of a passenger's seat 74. An air cleaner 53 is arranged along a front side bottom face of a fuel tank 75. Since the passenger's seat 74 is arranged one stage higher level than that of the rider's seat 66, a space to arrange the fuel tank 75 on the downward side of the passenger's seat 74 can sufficiently be secured and also the helmet containing box 72 can be provided in the rearward of the fuel tank 75. Since a large space can be obtained on a forward side of an internal combustion engine 20, the space can be utilized as articles containing portion or for arrangements of accessories. A scooter type motorcycle 80 according to still another embodiment will be described accompanying an illustration in Fig. 6. The present scooter type motorcycle 80 is constituted in such a manner as that an internal combustion engine 81 mounted is provided with a transmission 82 integral with a crank case, a rear fork 83 which is independent of the internal combustion engine 81 and is a separate body from the transmission 82, is supported in a freely swingable manner, while a rear wheel 84 is pivotally supported at a rear end thereof. In a car body frame, a pair of left and right main pipes 86, 86, which is extending from an upper portion of a head pipe 85 have roughly the same shapes as those of the main pipes 2 described above, are composed of front side inclination portions 86a, central horizontal portions 86b, rear side inclination portions 86c, and rear side horizontal portions 86d, further, a pair of left and right down pipes 87, 87 which are extended from a lower portion of the head pipe 85, are composed of front side inclination portions 87a, central horizontal portions 87b, and rear side inclination portions 87c, however, these down pipes are different from the down pipes 4 described above, the central horizontal portions 87b are extended backward long and the rear side inclinations 87c which is bent oblique upward at back ends of the central horizontal portions 87b, are coupled to the rear side horizontal portions 86d of the main pipes 86. The internal combustion engine 81 is mounted at rear half portions of the central horizontal portions 86b and 87b of the upside main pipes 86 and the downside down pipes 87 respectively, a fuel tank 85 is mounted at front half portions thereof 86b and 87b, and floor portions 99 are formed on the left and right sides of the fuel tank 98. Accordingly, the internal combustion engine 81 is located more rearward than that of the floor portions. A rider's seat 88 covers on the upward side of the internal combustion engine 81 in a freely openable and closable manner. A passenger's seat 89 is arranged at one stage high level in the rearward of the rider's seat 88, a helmet containing box 90 is provided on the downward side thereof 89, and an air cleaner 91 and carburetors 92 are disposed between the helmet containing box 90 and cylinders. A bracket 95 is mounted at a back end of transmission cases of a transmission 82 provided to rearward of a crank case of the internal combustion engine 81, a front end of the rear fork 83 is pivotally mounted on the bracket 95 by means of a pivot 96, and the rear wheel 84 is pivotally supported at the rear end of the rear fork 83 which is moved in a vertically swingable manner. A rear cushion 97 is interposed between a center somewhat close to a rear position of the rear fork 83 and a front portion of the rear side horizontal portions 86d of the main pipes 86. Since the rear wheel 84 is supported via the rear fork 83 which is swingable independent of the internal combustion engine 81, a swinging section is remarkably lightened its weight, so that a high speed travelling property can be improved eventually. Further, since the swinging section is small, there is no need to secure a large space on a periphery thereof, therefore efficient arrangement of parts can be realized. In addition, since the internal combustion engine 81 is arranged in the rearward of the floor portions 99, large spaces are capable of securing for the floors and thus, at the same time, the fuel tank 98 can be provided at the floor portions 99. A scooter type motorcycle is provided for improving a high speed travelling property by forming a rear wheel supporting member, being a separate body from an internal combustion engine, in a freely swingable manner, for realizing efficient arrangement of parts, and for securing large spaces for floors. In a scooter type motorcycle having lower deck type floors 64a, the scooter type motorcycle includes an internal combustion engine 20 arranged in the rearward of the floors 64a and on a downward side of a seat 66, and a rear wheel 44 supported via a supporting member which is swingable independent of the internal combustion engine 20.

Claims: A scooter type motorcycle having a lower deck type floor comprising: an internal combustion engine (20) arranged in the rearward of said floor (64a) and a downward side of a seat; a rear wheel (44) supported via a supporting member (32) swingable independent of said internal combustion engine, said supporting member (32) includes a left fork portion (32c) having a front end (32a) and a right fork portion (31 c) having a front end (31 a), characterized in that said supporting member (32) includes a belt type automatic transmission (30) and is pivotally supported coaxially with a crank shaft (23) of said internal combustion engine (20) and said left and right fork portions (32c, 31 c) being supported on both sides of a crankcase (21) of the internal combustion engine (20). A scooter type motorcycle according to claim 1, wherein a space for disposing accessories and articles provided on a frontward side of cylinders (22) of said internal combustion engine provided in a forward tilted manner. A scooter type motorcycle according to claim 1, further comprising: a passenger's seat (67) provided at one stage high level to rearward of a rider's seat (66); a helmet containing box (54) arranged on a downward side of the passenger's seat; and an air cleaner (53) arranged along a bottom face of the helmet containing box.

Inventors: INAYAMA YOICHI, OHMIKA YASUSHI, INAYAMA, YOICHI, OHMIKA, YASUSHI, Inayama, Yoichi, c/o K.K. Honda Gijutsu Kenkyusho, Ohmika, Yasushi, c/o K.K. Honda Gijutsu Kenkyusho
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 2000
Main classification: B62K11
IPC codes: F02B75, B62K11, F02B61, B62K19, B62M13