Title of Invention

"FRONT SUSPENSSION OF A MOTORCYCLE"

Abstract

[Solving Means] In a motorcycle in which a front swing arm 42 is vertically swingably mounted on a front portion of a main frame 2 and a front wheel is rotatably mounted on said front swing arm, a resin spring 44 for relaxing impact of said front swing arm in the swing direction is interposed between said main frame and said front swing arm. [Effect] The resin spring exhibits a spring action with a small stroke only by elastic deformation, and receives a load in a wide range from a small load to a large load. [Selected .Drawing] Fig. 7

Full Text

[Detailed Description of the Invention] [0001] [Technical Field of the Invention] The present invention relates to a front suspension of a motorcycle. [0002] [Related Art] As shown in Fig. 1 of Japanese Patent Laid-open No. Hei 8-175477 entitled "Apparatus for Switching Powers of Engine and Motor for Motorcycle and the Like", a front suspension of a motorcycle is generally of a telescopic type. In a motorcycle including such a telescopic type suspension, a suspension and a steering are integrally assembled. [0003] [Problem to be Solved by the Invention] In the above-described telescopic type suspension which has been extensively used, since a load of a front half of a vehicular body is all applied to a head pipe, a body frame must have a high rigidity. The head pipe also specifies the steering characteristic, and accordingly, the head pipe is desired to have an alignment (caster or trail) suitable for the kind of vehicle. That is to say, the head pipe is generally provided with a high rigidity frame around the head pipe for each kind of vehicle, resulting in the reduced flexibility. On the other hand, there is known a swing arm type suspension for vertically swingably supporting a front wheel, which suspension is separated from a steering system connected to a head pipe. Such a suspension, however, is limited in terms of space on the front side, so that it is difficult to ensure a space for swing and stroke motions of a swing arm. [0004] [Means for Solving the Problem] The present inventors have studied a suspension as an alternative to the telescopic type suspension in order to reduce the weight of a body frame, looked over the structure of the suspension system again, and developed a new suspension structure with a steering system separated from a suspension system. According to the present invention, there is provided a motorcycle in which a front swing arm is vertically swingably mounted on a front portion of a main frame and a front wheel is rotatably mounted on the front swing arm, characterized in that a resin spring for relaxing impact of the front swing arm in the swing direction is interposed between the main frame and the front swing arm. [0005] An impact force of the front swing arm in the swing direction is transmitted to the resin spring, and the resin spring is elastically deformed, to exhibit a spring action, thereby relaxing the impact force. The resin spring exhibits a spring action with a small stroke only by elastic deformation, and receives a load in a wide range from a small load to a large load. The resin spring having such a configuration is suitable for a front swing mechanism requiring a small stroke. [Brief Description of the Drawings] [Fig. 1] A side view of a motorcycle according to the present invention. [Fig. 2] A side view of a main frame and its neighborhood according to the present invention. [Fig. 3] A plan view of the main frame, a front suspension system, a rear suspension system, and a steering system according to the present invention. [Fig. 4] A side view of the main frame, the front suspension system, and the steering system according to the present invention. [Fig. 5] A plan view of the main frame, the front suspension system, and the" steering system according to the present invention. [Fig. 6] An exploded side view of the main frame and a head pipe post according to the present invention. [Figs. 7(a) and 7(b)] Views of a structure of mounting a resin spring according to the present invention. [Fig. 8] A front view of the main frame and the head pipe post according to the present invention. [Fig. 9] An exploded perspective view of the main frame, the front suspension, and the steering system according to the present invention. [Fig. 10] A plan view of the main frame according to the present invention, showing a state in which the main frame contains batteries. [Fig. 11] A sectional side view of the main frame according to the present invention, showing a state in which the main frame contains batteries. [Fig. 12] A sectional view taken on line 12-12 of Fig. 11. [Figs. 13(a) and 13(c)] 4 Views each illustrating a relationship between a front swing arm and a front wheel [Embodiment of the Invention] Hereinafter, embodiments of the present invention ^ will be described with reference to the accompanying drawings. In the drawings, the "front side", "rear side", "left side", "right side", "upper side", and "lower side" are based on the running direction of a vehicular body, and character Fr indicates the front side; Rr is the rear side; L is the left side; and R is the right side. In addition, the drawing should be viewed in the direction of characters. Fig. 1 is a side view of a motorcycle according to the present invention. In a motorcycle 1, a main frame 2 composed of a frame body serving as a battery containing box is disposed on the lower side of a center portion of a vehicular body, and at a front portion of the main frame 2 are mounted a swing type front suspension system 4 for suspending a front wheel 3 and a steering system 5 separated from the front suspension system 4. Also at a rear portion of the main frame 2 is mounted a rear suspension system 8 for suspending a power unit 6 and a rear wheel 7. An engine 6a and a motor (electric motor) 6b are taken as a drive source of the power unit 6. Each of the front wheel 3 and the rear wheel 7 used in the present invention particularly adopts a large-sized wheel ( diameter: 14 to 20 inches). [0007] In the motorcycle 1, on the back side (depth direction in the drawing) of the rear wheel 7 are disposed an air cleaner 11, an exhaust pipe 12, a muffler 13, and-a tail pipe 14. A front fender 15, a front cover 16, a front handle cover 17, a center cowl 18, a rear cowl 19, and a rear fender 21 are disposed from front to rear in this order in such a manner as to cover the vehicular body. Reference numeral 22 indicates a leg shield; 23 is a horn; 24 is a front lamp; 25 is a handlebar; 25a is a grip; 26 is a seat; 27 is a helmet box; 27A is a helmet; 28 is a tail lamp; 71 is a baffle duct; 72 is a radiator; and 73 is a fan. [0008] Fig. 2 is a side view of the main frame and its neighborhood according to the present invention. The power unit 6 and the rear suspension system 8 will be described below. The power unit 6 is swingably mounted on an upper rear portion of the main frame 2 via a rear pivot 31, and the rear wheel 7 is mounted on the power unit 6. Seat rails 32 for mounting the se,at 27 and the helmet box 28 shown in Fig. 1 are mounted on an upper rear portion of the main frame 2. A rear cushion 33 is mounted on the seat rails 32 at a position before the rear wheel 7 in the drawing. A combination structure of the main frame 2 disposed on the lower front portion of the motorcycle 2, the seat rails 32 on the upper rear portion of the main frame 2, and the head pipe post 51 on the upper front portion of the main frame 2, constitutes a body frame 57. [0009] Fig. 3 is a plan view of the main frame, the front suspension system, the rear suspension system, and the steering system according to the present invention. A front swing arm 42 (which will be described later) of the front suspension system 4 extends forward from the front portion of the main frame 2. The front wheel 3 is supported by the front swing arm 42 in a cantilever manner. The power unit 6 extends rearward from the rear portion of the main frame 2, and the rear wheel 7 is supported by the power unit 6 in a cantilever manner. The front swing arm 42 is offset to one side (right side) from the vehicular center C, and the power unit 6 is offset to the other side (left side) from the vehicular center C, so that the motorcycle 1 has a preferable balance of weight between the right and left sides. [0010] Fig. 4 is a side view of the main frame, the front suspension system, and the steering system according to the present invention. The front suspension system 4 has the front swing arm 42 formed into an approximately inverse-U shape in a side view. The front swing arm 42 extends from the lower front portion of the main frame 2 via a front pivot 41, and the front wheel 3 is rotatably supported by the front swing arm 42. To be more specific, a knuckle 43 mounted on the front wheel 3 is mounted at the leading end of the front swing arm 42 in such a manner as to be rotatable right and left. [0011] The front suspension system 4 has a bumper member 44 and a front damper 45 separated from the bumper member 44. The bumper member 44 is provided for relaxing impact transmitted (from a road surface) in the swing direction of the front swing arm 42. The front damper 45 is provided for damping vibration in the swing direction of the front swing arm 42. More specifically, a resin spring (bumper member) 44 for relaxing impact in the swing direction of the front swing arm 42 is interposed between the main frame 2 and the front swing arm 42, and the front damper 45 is mounted between the main frame 2 and the front swing arm 42. [0012] The structure of mounting the front damper 45 will be described in detail. One end of the front damper 45 is supported on the right side (back side in the drawing) of a base portion of the head pipe post 51 (which will be described later) by a pivot 46, and the other end of the front damper 45 is supported on the left side of a top portion of the front swing arm 42 by a pivot 47. In addition, the one end of the front damper 45 may be directly mounted on the main frame 2. [0013] The structure of the steering system 5 will be described below. The head pipe post 51 extends obliquely upward from an upper front portion of the main frame 2, and a head pipe 52 is fixed at the leading end of the head pipe post 51. A handle post 53 is rotatably mounted around the head pipe 52, and a steering arm 54 is mounted at the lower end of the handle post 53. The leading end (lower end) of the steering arm 54 is connected to a knuckle 43 via a link mechanism 55. [0014] The link mechanism 55 is composed of a combination of a first link 55a connected to the leading end of the steering arm 54 and a second link 55b connected to the knuckle 43. The link mechanism 55 is disposed in the front wheel 3 having a relatively large diameter. The arrangement of the link mechanism 55 in the front wheel 3 leads to effective use of a space, and therefore, since a space on the lower and rear sides from the head pipe 52 can be sufficiently ensured, it becomes possible to enhance the degree of freedom in design of the motorcycle 1. In the case of a scooter type motorcycle in which a passenger's step 83 provided on the motorcycle 1 is removed and instead a low step floor on which driver's feet are to be placed is provided, it is possible to sufficiently ensure a space around the driver's feet. [0015] Reference numeral 35 indicates a front brake disk; 36 is a caliper mounted on the knuckle 43; and 37 is a bearing for supporting the rear pivot 31 (see Fig. 2). On a lower rear portion of the main frame 2 are mounted a main stand 81, the passenger's step 83, and a side stand 84. [0016] Fig. 5 is a plan view of the main,, frame, the front suspension system, and the steering system according to the present invention, in which the link mechanism 55 is shown in development. Referring to Fig. 5, the front swing arm 42 extends forward from the right front portion of the main frame 2 via the front pivot 41 while being curved rightward in such a manner as to bypass the front wheel 3. On the other hand, the steering arm 54 extends forward from the lower end of the handle post 53 positioned at the vehicular center (center line of the vehicular body) C while being curved rightward in such a manner as to bypass the front wheel 3. [0017] As is apparent from Fig. 5, the center of the head pipe post 51 is offset a dimension L to one side (left side) from the vehicular center C; the front damper ( damper) 45 is disposed on the other side (right side) from the vehicular center C in such a manner as to be adjacent to the head pipe post 51; and the front damper 45 extends in parallel to the vehicular center C. Accordingly, since the front damper 45 can be disposed as close to the vehicular center C as possible, the bending moment applied to the front damper 45 can be suppressed as much as possible. This makes it possible to set t^he strength of the front damper 45 at a low value, and hence to make compact (miniaturize) the front damper 45. The front damper 45 having such a configuration is suitable for the swing arm mechanism provided on the front side variously limited in terms of space. The resin spring 44 is disposed at the vehicular center C. Reference numeral 36a indicates a piston and 36b is a brake pad. [0018] Fig. 6 is an exploded side view of the main frame and the head pipe post according to the present invention. In general, the caster angle of a steering slightly varies for each kind of vehicle, and accordingly, a body frame formed integrally with a head pipe must be exchanged into a new one each time the caster angle varies. [0019] In this embodiment, the main frame 2 is separable from the head pipe post 51. Concretely, the main frame 2 is of a frame body structure serving as a battery containing box to enhance the flexibility, and further it is made from an aluminum alloy by casting to enhance the rigidity. The head pipe post 51 is thus mounted on the main frame 2 with a plurality of bolts Bl. [0020] With adoption of this structure, even if the kind of vehicle is changed, the main frame 2 can be shared with only the head pipe post 51 exchanged, to thereby increase the degree of freedom in design. Further, as shown in Fig. 4, since the swing arm type front suspension system 4 is adopted in which the main frame 2 having a large rigidity receives a large load from the front wheel 3 via the front swing arm 42 and the front pivot 41, it is possible for the main frame 2 to positively, effectively receive a large load. As a result, a large load is not applied to the head pipe post 51. Even in the case of a scooter type motorcycle in which the passenger's step 83 provided on the motorcycle 1 is removed and instead a low step floor on which driver's feet are to be placed is provided, the main frame 2 having a high rigidity can receive a large load from the front wheel 3 via the front pivot 41. [0021] Figs. 7(a) and 7(b) are views showing a structure of mounting the resin spring according to the present invention, wherein Fig. 7(a) shows a cross-sectional structure seen from one side, and Fig. 7(b) shows a plane structure. The resin spring 44, which is a r^sin block having an elasticity for allowing a spring action, has two holes (mounting hole 44a and spring force setting hole 44b) passing therethrough from right to left (front to back in the drawing). The resin spring 44 is mounted on the front portion of the main frame 2 at a position separated a specific dimension H upward from the front pivot 41. The structure of mounting the resin spring 44 will be described in detail. A mounting plate 48 is inserted in the mounting hole 44a of the resin spring 44 and is mounted on the front portion of the main frame 2. Meanwhile, front and rear sides of the resin spring 44 are clamped between the backface of the front swing arm 42 and a clamping plate 49 mounted on the backface of the front swing arm 42. [0022] Fig. 8 is a front view of the main frame and the head pipe post according to the present invention, showing a structure in which one end of the front damper 45 is supported on the right side of the base portion of the head pipe post 51 by the pivot 46. Reference numeral 2a indicates a bearing for supporting the front pivot 41, and 2b is a mounting portion for mounting the resin spring mounting plate 48. [0023] Fig. 9 is an exploded perspective^view of the main frame, the front suspension, and the steering system according to the present invention. The configurations of the front suspension system 4 and the steering system 5 will be described in detail with reference to Fig. 9. A supporting pipe 42a of the front swing arm 42 is mounted to the right and left bearings 2a of the main frame 2 by means of the front pivot 41. The clamping plate 49 is connected to connecting portions 42c formed on a plate portion 42b of the front swing arm 42 with upper and lower bolts B2, and the resin spring 44 is clamped between the backface of the plate portion 42b and the clamping plate 49. The mounting plate 48 is inserted in the mounting hole 44a of the resin spring 44, and right and left ends of the mounting plate 48 are mounted on the mounting portions 2b of the main frame 2 with bolts B3. The head pipe post 51 is mounted on the upper front portion of the main frame 2 with the bolts Bl. The one end of the front damper 45 is supported on the base portion of the head pipe post 51 by means of the pivot 46, and the other end of the front damper 45 is supported on the top portion of the front swing arm 42 by means of the pivot 47. The head pipe 52 is provided at the leading end of the head pipe post 51, and the handle post 53 is rotatably mounted on the head pipe 52. The steering arm 544is mounted at the leading end of the handle post 53, and the link mechanism 55 is connected to the leading end of the steering arm 54. At the leading end of the front swing arm 42 is provided a stem receiving portion 42d for laterally rotatably mounting a stem 43a of the knuckle 43 (see Fig. 4). [0024] Fig. 10 is a plan view of the main frame according to the present invention, showing a state in which the main frame contains batteries. As shown in Fig. 10, a plurality of batteries Ba are contained in the main frame 2. That is to say, the plurality of batteries Ba are disposed on the lower side of the front portion of the body frame 57. To be more specific, the main frame 2 has right and left side members 2c extending in the longitudinal direction of the vehicular body. Front ends of the right and left side members 2c are joined to each other by means of a front cross-member 2d, and rear ends of the right and left side members 2c are joined to each other by means of a rear cross-member 2e formed into a portal shape in a rear view. [0025] The main frame 2 has a shape in which the bottom of a central portion falls out except for the, front side, and a containing case 61 serving as a bottom plate is mounted on the main frame 2. Most of the plurality (five pieces in Fig. 10) of batteries Ba are placed on the bottom plate. The plurality of batteries Ba, which are adapted to supply a power to the motor 6b shown in Fig. 1, are arranged in a stagger pattern of 3-rows X2-columns between the right and left side members 2c. Accordingly, the main frame 2 has a wide width. [0026] Fig. 11 is a sectional side view of the main frame according to the present invention, showing a state in which the main frame contains batteries. As shown in Fig. 11, the portal shaped rear cross-member 2e is disposed in such a manner as to cross the upper side from the plurality of batteries Ba. [0027] Fig. 12 is a sectional view taken on line 12-12 of Fig. 11, showing a state in which the main frame 2 with its bottom opened is closed by the containing case 61. The containing case 61 is a light alloy made case for containing a unit (not shown) composed of an electronic circuit for driving and controlling the motor 6b (see Fig. 1) and the like. The containing case 61 includes a case main body 62 and a lid 63 for closing an upper portion of the case main body 62. The containing case 61 is inserted from the lower side into an opening of the main frame 2, and flanges 62a of the containing case 61 are mounted on a lower surface of the main frame 2 with bolts B4. A combination structure of the containing case 61 and the above unit contained in the containing case 61 is hereinafter called "a control unit". As described above, the body frame 57 includes a pair of the right and left side members (frames) 2c extending under the head pipe 52 and then substantially in parallel to the ground. The present invention is characterized in that the control unit is fixed to lower portions of the right and left side members 2c in such a manner as to extend between the right and left side members 2c, and the plurality of batteries Ba are mounted on the control unit. [0028] A resin made partitioning plate 64 for partitioning the plurality of batteries Ba is superimposed from the upper side of the main frame 2 onto the containing case 61, and is mounted on the upper surface of the main frame 2 with bolts B5. It is to be noted that the partitioning plate 64 is not necessarily provided. On the other hand, the plurality Of batteries Ba are covered with a battery cover 65, and flanges 65a of the battery cover 65 are mounted on the upper surface of the main frame 2 with the bolts B5. [0029] As described above, since most of the batteries Ba are placed on the containing case 61 serving as the bottom plate of the main frame 2, it is possible to eliminate the necessity of provision of a member for receiving the batteries Ba such as a tray and hence to reduce the number of parts. Since the bottom of the main frame 2 is closed by the containing case 61, the rigidity of the main frame 2 can be increased. Since the containing case 61 is exposed downward from the main frame 2, the amount of heat radiation from the unit becomes large. By forming radiation fins 62b on the lower surface of the containing case 61, it is possible to further increase the amount of heat radiation from the unit. Since the containing case 61 is made from a light alloy having a good thermal conductivity, heat generation from the batteries Ba can be easily diffused. [0030] The reason why the front swing arm 42 is formed into the inverse-U shape in a side view w2.11 be described with reference to Figs. 13(a) to 13(c). Figs. 13(a) to 13(c) are views each illustrating a relationship between the front swing arm and the front wheel. Referring to Fig. 13(a), a member indicated by a solid line is the front swing arm 42 in this embodiment, and a member indicated by an imaginary line is a front swing arm Fa in a comparative example. The front swing arm 42 formed into the inverse-U shape is overlapped on the outer periphery edge of the front wheel 3 at a point PI close to the center P of the front wheel 3. On the contrary, the front swing arm Fa in the comparative example, which is an arm horizontally extending at the height of the center of the front wheel 3, is overlapped on the outer periphery edge of the front wheel 3 at a point P2 most remote from the center P of the front wheel 3. [0031] Fig. 13(c) is a plan view showing a relationship between the front swing arm Fa in the comparative example and the front wheel 3. In the case where the front wheel 3 is steered at a steering angle 6 , a tilt distance from the vehicular center C to the outer edge of the front wheel 3 is indicated by character S2. The front swing arm Fa in the comparative example is required to be, bypassed the large tilt distance S2 so as not to be brought in contact with the front wheel 3. As a result, the projecting amount of the front swing arm Fa in the width direction of the vehicular body becomes large. [0032] Fig. 13(b) is a plan view showing the relationship between the front swing arm 42 in this embodiment and the front wheel 3. Since the front swing arm 42 is overlapped on the outer peripheral edge of the front wheel 3 at the point PI, in the case where the front wheel 3 is steered at the steering angle 9 , the tilt distance from the vehicular center C to the outer edge of the front wheel 3 becomes SI which is smaller than the tilt distance S2 in the comparative example. As a result, the front swing arm 42 may be bypassed the small tilt distance SI so as not to be brought in contact with the front wheel 3. That is to say, the projecting amount of the front swing arm 42 in the width direction of the vehicle becomes small. Since the projecting amount of the front swing arm 42 is small, the motorcycle can be miniaturized. That is to say, the front swing arm 42 formed into the inverse-U shape is overlapped on the outer peripheral edge of the front wheel 3 at the position (point Pi) higher than the center 0 of the front wheel 3. The amplitude of the steered front wheel 3 at the overlapped position is smaller than that of the front wheel 3 at the outer peripheral edge which is at the height of the center O of the front wheel 3. As a result, the front swing arm 42 may be bypassed so as not to be brought in contact with the front wheel 3 at the position where the amplitude of the front wheel 3 is small. [0033] The function of the front suspension system 4 will be described with reference to Fig. 4 and Figs. 7(a) and 7(b). As shown in Fig. 4, the front damper 45 acts to damp vibration of the front swing arm 42 in the swing direction. On the other hand, as shown in Figs. 7(a) and 7(b), an impact force of the front swing arm 42 in the upward swing direction is transmitted from the backface of the front swing arm 42 to the resin spring 44, and an impact force of the front swing arm 42 in the downward swing direction is transmitted from the clamping plate 49 to the resin spring 44. At this time, the resin spring is elastically deformed, to exhibit a spring action, thus relaxing the impact force. In this way, the front suspension*system 4 is capable of relaxing an impact force by the resin spring 44, and damping vibration by the front damper 45. [0034] As described above, the resin spring 44 exhibits a spring action with a small stroke only by elastic deformation, and it receives a load in a wide range from a small load to a large load. The resin spring 44 is also extremely smaller in size than a coil spring. As compared with a related art suspension in which a coil spring and a damper are integrally assembled, the suspension system of the present invention acts with a small stroke against a load in a wide range, and is reduced in size enough to be easily disposed in a narrow space. [0035] [Effect of the Invention] The present invention having the above configuration exhibits the following effects: According to the invention described in claim 1, since a resin spring for relaxing impact of a swing arm in the swing direction is interposed between a main frame and the front swing arm, an impact force of the front swing arm in the swing direction is transmitted to the resin spring, and the resin spring is elastically deformed, to exhibit a spring action, thereby relaxing the impac^ force. The resin spring exhibits a spring action with a small stroke only by elastic deformation, and receives a load in a wide range from a small load to a large load. The resin spring having such a configuration is suitable for a front swing mechanism requiring a small stroke. [Reference Numerals] 1: motorcycle, 2: main frame, 3: front wheel, 41: front pivot, 42: front swing arm, 43: knuckle for front wheel, 44: resin spring, 45: front damper, 48: mounting plate, 49: clamping plate, 54: steering arm, 55: link mechanism [Claim 1] A motorcycle in which a front swing arm is vertically swingably mounted on a front portion of a main frame and a front wheel is rotatably mounted on said front swing arm, characterized in that a resin spring for relaxing impact of said front swing arm in the swing direction is interposed between said main frame and said front swing arm. 2. A motorcycle substantially as herein described with reference to the accompanying drawings.

Documents:

2545-del-1998-abstract.pdf

2545-del-1998-claims.pdf

2545-del-1998-correspondence-others.pdf

2545-del-1998-correspondence-po.pdf

2545-del-1998-description (complete).pdf

2545-del-1998-form-1.pdf

2545-del-1998-form-13.pdf

2545-del-1998-form-2.pdf

2545-del-1998-form-3.pdf

2545-del-1998-form-4.pdf

2545-del-1998-form-6.pdf

2545-del-1998-gpa.pdf

2545-del-1998-petition-137.pdf

2545-del-1998-petition-138.pdf