MOTORCYCLE

Abstract: A motorcycle has a frame assembly including a main frame (5) supporting front (1) and rear (3) wheels on a central line (C0) thereof, a connecting means (6) mounted on the main frame (5) between the front (1) and rear (3) wheels, and a subframe (7) mounted on the connecting means (6) and being capable of banking laterally about the connecting means (6). At least one of the front (1) and rear (3) wheels is a drive wheel, at least the drive wheel (3) being capable of preventing the main frame (5) from banking laterally. Centrifugal forces generated upon cornering are counterbalanced by centripetal forces produced when only the subframe (7) banks laterally, and the drive wheel (3) supported on the main frame (5) which does not bank has an increased road gripping force. Thus, high-speed cornering is made possbile.

Description: The present invention relates to a motorcycle. When a motorcycle makes a turn or corners, centrifugal forces produced dependent on the weight of the motorcycle, the speed of travel of the motorcycle, and the cornering radius are counterbalanced by centripetal forces generated by causing the motorcycle to bank. Conventional motorcycles have unitary frames supporting front and rear wheels. Upon cornering at high speed, the motorcycle frame is required to bank to a large degree. The front and rear wheels supported on conventional motorcycle frames have tires of circular cross section which are shaped to allow the motorcycle frames to bank. When the motorcycle corners, the side forces imposed on the front and rear wheels that are inclined or bank laterally are increased in proportion to the banking angle of the frame. When a conventional motorcycle approaches a corner at high speed such as during sports racing, however, the speed of the motorcycle must be reduced to prevent the cornering or side forces exceeding the available traction. GB 2082987 discloses a three-wheel vehicle comprising an engine bearing sub frame which is maintained substantially upright by a pair of rear road wheels disposed at either side of the subframe. The vehicle further comprises a main frame to which are connected the vehicle rider's seat, the steering assembly and the single steerable front wheel. The main frame is connected to the subframe by a coupling which enables the main frame to bank relative to the subframe. According to the present invention there is provided a motorcycle comprising: a front and a rear wheel; a frame assembly including a front frame supporting the front wheel, a main frame supporting the rear wheel, and connecting means interconnecting the front and main frames, the said means being disposed in a longitudinal direction of the frame assembly, the front frame being capable of banking laterally about the connecting means, characterized in that the single rear wheel is capable of preventing the main frame from banking laterally, and in that the frame assembly further comprises a seat frame, swingably mounted on the front frame. Preferably the connecting means includes a connecting shaft disposed in the longitudinal direction of the frame assembly. In a preferred embodiment the rear wheel includes a tyre having a broad U-shaped cross section; the tyre preferably having a flat central ground engaging portion. The steering handle is preferably mounted on the front frame for steering the front wheel. Preferably also the seat frame extends above the main frame. The driver's seat and foot rests may be mounted on the seat frame. Alternatively, the driver's seat may be mounted on the seat frame and the driver's foot rests may be mounted on the main frame. A mechanism may be provided for limiting the range in which the front frame banks. Preferably a device is provided for angularly moving the seat frame according to a banking angle of the front frame. The device may include means for angularly moving the seat frame in a direction in which the front frame banks. With the above motorcycle, centrifugal forces generated upon cornering are counterbalanced by centripetal forces produced when the front frame and seat frame bank laterally, and the rear wheel supported on the main frame which does not bank has an increased road gripping force, so that high-speed cornering is made possible. If the seat frame is angularly moved in a horizontal direction during cornering, the banking angle of the front frame is reduced and the burden on the front wheel is smaller by an extent commensurate with the centripetal forces produced by angularly moving the seat frame. Since the seat frame can be angularly moved in the same direction as the banking direction of the front frame, the degree to which the front frame banks is reduced for high-speed cornering. For a better understanding of the present invention and to show how it may be carried into effect reference will now be made by way of example to the accompanying drawings, in which: FIGS. 1, 2 and 3 are perspective, side elevational, and front elevational views of a motorcycle according to a first embodiment of the present invention; FIG. 4 is a side elevational view of an internal structure of the motorcycle shown in FIGS. 1, 2, and 3; FIG. 5 is a front elevational view of the motorcycle of FIGS. 1, 2 and 3 as it banks upon cornering; FIG. 6 is an enlarged cross-sectional view taken along line XVIII - XVIII of FIG. 4; FIG. 7 is a fragmentary side elevational view of a motorcycle in accordance with a second embodiment of the present invention; FIG. 8 is an enlarged cross-sectional view taken along line XX - XX of FIG. 7; FIG. 9 is a fragmentary side elevational view of a motorcycle in accordance with a third embodiment of the present invention; FIG. 10 is an enlarged cross-sectional view taken along line XXII - XXII of FIG. 9; FIG. 11 is a fragmentary side elevational view of a motorcycle in accordance with a fourth embodiment of the present invention; FIG. 12 is an enlarged cross-sectional view taken along line XXIV - XXIV of FIG. 11; FIG. 13 is a fragmentary side elevational view of a motorcycle in accordance with a fifth embodiment of the present invention; FIG. 14 is a fragmentary bottom view of the motorcycle shown in FIG. 13; FIG. 15 is a fragmentary side elevational view of a motorcycle according to a sixth embodiment of the present invention; FIG. 16 is a fragmentary bottom view of the motorcycle shown in FIG. 15. FIG. 17 is a fragmentary side elevational view of a motorcycle according to a seventh embodiment of the present invention; FIG. 18 is a fragmentary bottom view of the motorcycle shown in FIG. 17; FIG. 19 is a fragmentary side elevational view of a motorcycle according to an eighth embodiment of the present invention; FIG. 20 is a fragmentary bottom view of the motorcycle shown in FIG. 19; FIG. 21 is a fragmentary side elevational view of a motorcycle according to a ninth embodiment of the present invention. A motorcycle according a first embodiment of the present invention will be described below with reference to FIGS. 1 to 6. The motorcycle has a front cowl 40, a pair of lateral extensions 41 projecting laterally from the front cowl 40, a pair of radiators 42 disposed in front openings 43 of the extensions 41, the extensions 41 having rear openings 44 for discharging air which has been introduced from the front openings 43 and passed through the radiators 42, a rear drive wheel 44 including a wide flat tire of a substantially U-shaped cross section, a front wheel 45 including a round tire, and a driver's riding seat 46. An inner structure in the front cowl 40 will be described below with reference to FIG. 4 . The inner structure includes a front frame 47, a main frame 48, and a seat frame 49. The front wheel 45 is supported on a steering shaft 51 by an axle 50. The steering shaft 51 has upper and lower ends coupled by pillow balls 52, 53 to ends of upper and lower swing arms 54, 55, respectively, the other ends of which are connected to the front frame 47. The swing arms 54, 55 are vertically swingable about their joints to the front frame 47 and also about the pillow balls 52, 53. A steering rod 57 has one end attached to the steering shaft 51 below the upper pillow ball 52. The other end of the steering rod 57 is attached to a lower portion of a handle 56 mounted on a front end of the front frame 47. The handle 56 is angularly movable in a plane normal to a plane formed by the steering shaft 51 and the upper and lower swing arms 54, 55 and substantially parallel to the upper swing arm 54. A damper unit 58 is coupled to the lower swing arm 55 and the front frame 47 for correcting vertical movement of a front portion of the motorcycle. The damper unit 58 has one end coupled to the lower swing arm 55 by a link 59 and a bracket 60, and also to a bracket 62 mounted on the front frame 47 through the link 59 and a link 61. An engine 63 and a transmission case 64 are mountred on the main frame 48. The main frame 48 has a basde portion 65 joined coaxially to a connecting shaft 66 of the front frame 47. Footsteps 67 are mounted on a lower portion of the main frame 48. The seat frame 49 disposed upwardly of the front frame 47 is pivotally supported on an attachment shaft 68 attached to the front frame 47 along a straight line connecting the joints between the upper and lower swing arms 54, 55 and the front frame 47. The seat frame 49 is angularly movable about the attachment shaft 68, and can bank, together with the front frame 47, about the connecting shaft 66 by which the front frame 47 and the base portion 65 of the main frame 48 are coupled to each other. The driver's riding seat 46 with a fuel tank 69 disposed therein is disposed on the seat frame 49 above the main frame 48. As shown in FIG. 6, a mechanism for angularly moving the seat frame 49 and the front frame 47 includes a connecting bracket 70 joined to the seat frame 49, a connecting member 71 pivoted to the connecting bracket 70, and a connecting member 72 pivoted to the connecting member 71 and swingable with the connecting shaft 66. The seat frame 49 is thus coupled to the main frame 48 through the connecting bracket 70 and the connecting members 71, 72. The seat frame 49 is also coupled to the front frame 47 through the connecting member 72, a connecting member 73 pivoted to the connecting member 72, and a connecting bracket 74 pivoted to the connecting member 73 and joined to the front frame 47. The bracket 70 and the connecting members 71, 72, 73 are connected by shafts 75a, 75b, 76a, 76b parallel to the connecting shaft 66, and angularly movable about these shafts 75a, 75b, 76a, 76b. The transmission case 64 has a sprocket 78, and a sprocket 79 is attached to the axle of the rear wheel 44, with an endless chain 80a being trained around the sprockets 78, 79. Upper and lower swing arms 81, 82 have ends pivoted to the transmission case 64 and extend between hte sprocket 79 and the axle of the rear wheel 44. The other ends of the upper and lower swing arms 81, 82 are coupled to upper and lower ends of a knuckle arm 80b mounted coaxially with and slidably against the axle of the rear wheel 44. A rear cushion 85 is mounted on the main frame 48 and coupled to a lower surface of the lower swing arm 82 through a bracket 83 and a link 84. Banking action of the motorcycle shown in FIGS. 1 to 6 will be described below. In FIG. 4 , when the driver shifts the weight to one side in order to tilt the motorcycle upon cornering, the front frame 47 is caused to bank about the connecting shaft 66, and the front wheel 45 and the seat frame 49 are also caused to bank with the front frame 47. The condition in which only the front frame 47 and those components coupled thereto are caused to bank will be described in detail with reference to FIG. 5 . As shown in FIG. 5 , the front wheel 45 and the front frame 47 are caused to bank upon cornering. The rear wheel 44 is however prevented from banking because it includes a wide flat tire and also because the front frame 47 is swingable about the connecting shaft 66. Therefore, as illustrated in FIGS. 5 and 6 , when the front frame 47 banks in the direction of the arrow Y1 upon cornering, the bracket 74 is turned to enable the seat frame 49 to bank about the connecting shaft 66 through the connecting members 73, 72, 71 and the bracket 70. At the same time, the seat frame 49 is turned about the attachment shaft 68 in the direction of the arrow Y2 which is the same as the banking direction. Since the wide flat rear wheel 44 does not bank, it provides a large area of contact with ground upon cornering. As the front frame 47 banks, the seat frame 49 banks and swings about the attachment shaft 68. Therefore, the center of gravity of the motorcycle can be shifted laterally a large distance. As a result, the motorcycle can make a high-speed turn. While the footsteps 67 are mounted on the main frame 48 in the above illustrated embodiment, the steps 67 may be mounted on the seat frame 49 if the angle of swinging movement of the seat frame 49 is to be increased. FIGS. 7 and 8 show a motorcycle according to a second embodiment of the present invention, the motorcycle being partly different from the motorcycle shown in FIG. 6. As shown in FIG. 8 , the seat frame 49 is coupled to the front frame 47 through a connecting bracket 70 of the frame 49, connecting members 86, 89, 90, and a connecting bracket 91. The connecting member 89 has its inrermediate portion pivotally connected to a connecting shaft 89a, parallel to the connecting shaft 66, of a connecting bracket 87 of the base portion 65, so that the connecting member 89 is coupled to the main frame 48. The brackets 70, 91 and the connecting members 86, 90, 89 are angularly movably coupled to connecting shafts 92, 93, 94, 95 parallel to the connecting shaft 66. When the front frame 47 banks in the direction of the arrow Y1 as shown in FIG. 8 , the bracket 91 is turned to enable the seat frame 49 to turn around the connecting shaft 66 in the direction of the arrow Y2 through the connecting members 90, 89, 86, 70. FIGS. 9 and 10 show a motorcycle according to a third embodiment, the views illustrating a device or mechanism for angularly moving the seat frame. As shown in FIG. 10 , the seat frame 49 is connected to the main frame 48 through the bracket 70 of the frame 49, a connecting member 96, and connecting members 100, 97 to a connecting bracket 98 of the base portion 65, so that the seat frame 49 is coupled to the main frame 48. The seat frame 49 is also connected to the front frame 47 through the connecting member 100 pivotally coupled to the connecting bracket 91 by a connecting shaft 99 parallel to the connecting shaft 66. The brackets 70, 98 and the connecting members 96, 100, 97 are angularly movably coupled to connecting shafts 101, 102, 103, 104 parallel to the connecting shaft 66. When the front frame 47 banks in the direction of the arrow Y1, the bracket 91 is turned to swing the connecting member 100 to cause the connecting members 96, 70 to turn the seat frame 49 about the attachment shaft 68 in the direction of the arrow Y2. FIGS. 11 and 12 show a motorcycle according to a fourth embodiment, the views illustrating a device or mechanism for angularly moving the seat frame. As illustrated in FIG.12 , the seat frame 49 is coupled to the main frame 48 by the bracket 70 of the frame 49, a connecting member 106 having one end connected to the bracket 70 by a pivot shaft 105 parallel to the connecting shaft 66, and a movable gear 109 having one end connected to the other end of the connecting member 106 by a pivot shaft 107 parallel to the shaft 66 and the other end meshing with a fixed gear 108 on the base portion 65 of the main frame 48. The gear 109 is coupled to the front frame 47 by a connecting bracket 91 connected to an intermediate portion of the gear 109 by a pivot shaft 110 parallel to the shaft 66. When the front frame 47 banks in the direction of the arrow Y1, the bracket 91 is turned and so is the upper end of the movable gear 109 meshing with the gear 108. The seat frame 49 is then turned about the attachment shaft 68 in the direction of the arrow Y2 through the member 106 and the bracket 70. FIGS. 13 and 14 show a device or mechanism for angularly moving the seat frame of a motorcycle according to a fifth embodiment of the present invention. As illustrated in FIG. 14, the seat frame 49 is coupled to the main frame 48 by the attachment shaft 68, a connecting member 111 having one end connected to the shaft 68, and an L-shaped connecting member 116 having one end coupled to the other end of the member 111 by a pivot shaft 112 and the other end connected to one end of an L-shaped connecting member 114 by a pivot shaft 115, the L-shaped connecting member 114 being swingable about an attachment shaft 113 on the base portion 65. The seat frame 49 is also coupled to the front frame 47 by a connecting member 118 joined to the other end of the connecting member 114 by a pivot shaft 117. At the time the front frame 47 banks in the direction of the arrow Y1, the seat frame 49 is turned about the attachment shaft 68 in the direction of the arrow Y2 through the connecting members 118, 114, 116, 111. The connecting member 114 may be coupled to the front frame 47, whereas the base portion 65 of the connecting member 118 may be coupled to the main frame 48. FIGS. 15 and 16 show a device or mechanism for angularly moving the seat frame of a motorcycle according to a sixth embodiment of the present invention. As shown in FIG. 16, the seat frame 49 is coupled to the main frame 48 by the attachment shaft 68, a connecting member 119 with one end joined to the shaft 68, a connecting member 121 having one end coupled to the other end of the connecting member 119 by a pivot shaft 120, and a swing gear 124 swingably coupled to the other end of the member 121 by a pivot shaft 122, the swing gear 124 being swingable about an attachment shaft 123 on the base portion 65 of the main frame 48. The seat frame 49 is also connected to the front frame 47 through a fixed gear 125 secured to the front frame 47 and held in mesh with the swing gear 124. When the front frame 47 banks in the direction of the arrow Y1, the seat frame 49 is turned about the shaft 68 in the direction of the arrow Y2 through the gears 125, 124 and the connecting members 121, 119. The swing gear 124 may be mounted on the front frame 47, and the fixed gear 125 may be mounted on the base portion 65 of the main frame 48. FIGS. 17 and 18 show a device or mechanism for angularly moving the seat frame of a motorcycle according to a seventh embodiment of the present invention. As shown in FIG. 18, the seat frame 49 is coupled to the main frame 48 by the attachment shaft 68, a bevel gear 126 mounted on the lower end of the shaft 68, and a bevel gear 128 meshing with the bevel gear 126 and mounted on an end of a connecting shaft 127 extending from the base portion 65 of the main frame 48 coaxially with the connecting shaft 66 through the front frame 47. When the front frame 47 banks in the direction of the arrow Y1, the attachment shaft 68 is turned with the frame 47 about the connecting shaft 66. Therefore, the bevel gear 126 on the attachment shaft 68 turns in the direction of the arrow Y2 around the bevel gear 128 in mesh therewith which is secured through the shaft 127 to the base portion 65 that does not bank. The attachment shaft 68 and the seat frame 49 are therefore turned in the direction of the arrow Y3. FIGS.19 and 20 show a device or mechanism for angularly moving the seat frame of a motorcycle according to an eighth embodiment of the present invention. As shown in FIG. 20, the seat frame 49 is coupled to the main frame 48 by the attachment shaft 68, a bevel gear 129 mounted on the lower end of the shaft 68, a bevel gear 130 meshing with the bevel gear 129 and mounted on one end of a connecting shaft 131, and a rotatable gear 132 mounted on the other end of the connecting shaft 131 and meshing with a fixed gear 133 fixed to the base portion 65 of the main frame 48. Upon banking of the front frame 47 in the direction of the arrow Y1, the rotatable gear 132 rotates in the direction of the arrow Y2 in mesh with the fixed gear 133, and the gear 129 is rotated in the direction of the arrow Y3 by the gear 130, so that the seat frame 49 is turned with the shaft 68 in the direction of the arrow Y3. FIG. 21 shows a motorcycle according to a ninth embodiment, the motorcycle having a device or mechanism for angularly moving the seat frame. In FIG. 21, the seat frame 49 is coupled to the main frame 48 by the attachment shaft 68, a hyraulic motor 134 mounted on the shaft 68, a hydraulic circuit 135 having one end connected to the hydraulic motor 134 , and a hydraulic pressure generating mechanism 136 connected to the other end of the hydraulic circuit 135 and having one end coupled to the base portion 65 of the main frame 48 coaxially with the connecting shaft 66, the hydraulic pressure generating mechanism 136 being disposed in the front frame 47. The hydraulic pressure generating mechanism 136 generates a hydraulic pressure corresponding to the banking angle of the front frame 47 with respect to the base portion 65 of the main frame 48. When the front frame 47 banks in the direction of the arrow Y1, a hydraulic pressure generated by the hydraulic pressure generating mechanism 136 is applied via the circuit 135 to the hydraulic motor 134. The shaft 68 and the seat frame 49 are turned in the direction of the arrow Y2 by a control mechanism (not shown) which controls the direction of rotation of the motor 134 according to the direction in which the front frame 47 banks.

Claims: A motorcycle comprising: a front and a rear wheel (45,44); a frame assembly including a front frame (47) supporting the front wheel (45), a main frame (48) supporting the rear wheel (44), and connecting means interconnecting the front and main frames (47,48) the said means being disposed in a longitudinal direction of the frame assembly, the front frame (47) being capable of banking laterally about the connecting means, characterized in that the single rear wheel (44) is capable of preventing the main frame (48) from banking laterally, and in that the frame assembly further comprises a seat frame (49), swingably mounted on the front frame (47). A motorcycle as claimed in claim 1, characterized in that, the connecting means includes a connecting shaft (66) disposed in the longitudinal direction of the frame assembly. A motorcycle as claimed in claim 1 or 2, characterized in that the rear wheel (44) includes a tire having a broad U-shaped cross section. A motorcycle as claimed in any one of claims 1 to 3, characterized in that the rear wheel (44) includes a tire having a flat central ground engaging portion. A motorcycle as claimed in any one of the preceding claims, characterized in that a steering handle (56) is mounted on the front frame (47) for steering the front wheel (45); and in that the seat frame (49), extends above the main frame (47). A motorcycle as claimed in claim 5, characterized in that a driver's seat (46) and foot rests (67) are mounted on the seat frame (49). A motorcycle as claimed in claim 5, characterized in that a driver's seat (46) is mounted on the seat frame (49) and the driver's foot rests (67) are mounted on the main frame (48). A motorcycle as claimed in any one of the preceding claims, characterized in that a mechanism is provided for limiting the range in which the front frame (47) banks. A motorcycle as claimed in any one of the preceding claims, characterized in that a device (134, 135, 136) is provided for angularly moving the seat frame (49) according to a banking angle of the front frame (47). A motorcycle as claimed in claim 9, characterized in that the device (134, 135, 136) includes means for angularly moving the seat frame (49) in a direction in which the front frame (47) banks.

Inventors: HAMANO, BIJI, HORIIKE, SATORU, KIMURA, SHIGERU, KUBO, MIKIO, MATSUZAKI, MASANOBU, NAKANO, YASUHIKO, OKANO, SHIGETAROU, OOKI, KENJI, YAMAMOTO, TOSHITERU
Applicants: HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1988
Main classification: B62K11
IPC codes: B62K25, B62K11, F02B61