Chain Guard Structure for Motorcycle Field of the Invention The present invention relates to a chain guard structure for a motorcycle having an upper box and a lower box enclosing an oscillating arm from above and. down attached to the swing arm to hold a rear wheel shaft in a rear end section, with the rear end sections of the upper case and the lower case being connected together. A chain-guard structure for a motorcycle formed with upper and lower boxes that enclose a swing arm from above and below attached to that swing arm is well known, for example, from patent publication 1. Patent Document 1 Japanese Patent of Open Publication Hei number 9-263278. However, the chain-guard structure of the related art described above is a complete chain guard having an upper box and a lower box attached to an oscillating arm to completely cover a chain for transmitting a rotational driving force from one power unit to one. rear wheel, but the rear end connection sections of the upper and lower boxes are arranged to extend on a central line of the arm extending in a longitudinal direction of the swing arm along the axle of the rear wheel axle. Specifically, the rear end of the upper case is curved downwardly around the rear end of the swing arm and does not appear to be lightweight.
The present invention has been conceived in view of the situation described above and an object of the invention is to provide a chain guard for a motorcycle having an upper box and a lower box attached to an oscillating arm to completely cover a chain, in order to improve The appearance of being lightweight. In order to achieve the above-described objective, the invention of claim 1 is a chain-guard structure for a motorcycle, which has an upper case and a lower case that enclose an oscillating arm from above and below attached to the oscillating arm to hold a rear wheel shaft in a rear end section, with the rear end sections of the upper case and the lower case being 'connected to each other, wherein the rear end connection sections of the upper case and the lower case are arranged decentered higher than a center line of the arm extending in a longitudinal direction of the swing arm along a shaft axis. According to the invention of claim 1, a rear end connection section for the upper and lower boxes is disposed higher than a central line of the arm, which means that when the general chain guard is seen from the side, it is provided an external appearance that the back of the chain guard rises in the back and it is possible to obtain an external appearance that improves the appearance of being lightweight. Also, the invention of claim 2, in addition to the structure of the invention of claim 1, has a front end of the rear end connection sections of the upper case and the lower case which is disposed more opposite than a rear end of the oscillating arm and with this structure, the rear end of the lower case is curved upwards around the rear end of the oscillating arm and the appearance of being of light weight is considerably improved and it is also possible to improve the ease of assembly using a rear end of the lower case as a guide section when the upper case is attached to the swinging arm. Also, the invention of claim 3, in addition to the structure of the invention of claim 2, has the upper case and the lower case made of different colors so that there is a great difference in the contrast between them and with this structure it is possible Give an external appearance that provides the appearance of being lightweight. The embodiments of the present invention based on the attached drawings will now be described. Figures 1 to 4 show an embodiment of the present invention. Figure 1 is a side elevational view of a motorcycle, Figure 2 is an elongated side elevational view of a chain guard, Figure 3 is an elongated cross-sectional view along line 3-3 in Figure 2 and Figure 4 is an elongated cross-sectional view along the length of the line 4-4 in Figure 2. First of all, in Figure 1, a vehicle frame 5 of this motorcycle comprises an arrival tube 6 for supporting a front fork 9 in a maneuverable manner, a main frame 7 extending down from the arrival tube 6 and a pair of left and right rear frames 8 ... which extend upwards to the rear part which is connected to a rear section of the main frame 7, with a front wheel WF being held axially at a bottom end of the front fork 9, a rod-shaped steering handle 10 which is connected to an upper part of the front fork 9 and a front bumper 11 covering the top part of the front wheel F which is SW held in the front fork 9. The hanging plates 12 ... are respectively fixed on both sides of a middle section of the main frame 7 and a pivot plate 13 is fixed on both rear sides of the main frame 7. An engine E having an axis of its cylinders inclined slightly upwards at the front is disposed below the main frame 7 and this engine E is suspended from the vehicle frame 5 supported by the hanging plates 12 ... and the pivot plate 13. A front end of a rear fork 14 is supported on the pivot plate 13 so as to be able to swing from one side to the other and a shaft 15 of the rear wheel WR is supported at a rear end of the rear fork 14. A rear shock absorber 16 is also provided between the rear frames 8 ... of the vehicle frame 5 and the rear fork 14. A fuel tank 17 and a storage box 18 arranged in front of the fuel tank 17 are supported above the rear wheel WR in the rear frames 8 ... and the fuel tank 17 and the upper part of the fuel tank 17 is covered, for example, by a row seat 19 in such a way that it can open and close. A vehicle cover 20 made of synthetic resin to cover the vehicle frame 5, part of the engine E, the fuel tank 17 and the storage box 18 is attached to the vehicle frame 5 and this vehicle cover 20 comprises front side covers 21 arranged on both sides, left and right, of the main frame 7, member shields 22 ... to connect the front parts of both front side covers 21 ... and cover running members from the front, a front top cover 23 to connect both member shields 22 in order to cover the arrival pipe 6 from the front, an upper cover 24 of the main frame connected to the front upper cover 23 in order to cover the arrival pipe 6 of the rear part and also cover the main frame 7 from above, a lower cover 25 which is connected to a lower part of the two front side covers 21 ... and a cover rear side tab 26 to cover the fuel tank 17 and the storage box 18 on both sides.
The seat 19 is disposed in an upper part of the rear side cover 26 able to open and close to store and remove items in the storage box 18 and also to supply fuel to the fuel tank 17 and a rear bumper 27 to cover the part from above a rear part of the rear wheel WR is connected to the rear side cover 26. The engine E constitutes the power unit P together with a transmission M and an output of the transmission M is carried through the chain 28 to the rear wheel WR. That is, an endless chain 28 is wound around a drive sprocket 30 fixed to the secondary shaft 29 of the transmission M and a drive sprocket 31 adapted to the rear wheel WR. Referring both to Figure 2, and Figure 3, the rear fork 14 is provided with a pair of spring arms 14a ... arranged on both left and right sides of the rear wheel WR, constructed in a Cylindrical rectangular in a lateral cross section and a front end of the rear fork 14 is supported on the pivot plate 13 of the vehicle frame 5 through a horizontal pivot shaft in order to be able to swing from one side to the other.
A wheel hub 33 of the rear wheel W is rotatably supported on the shaft 15 through a pair of left and right ball bearings 34 ... and an inner cylindrical wheel collar 25 surrounding the shaft 15 is interposed between the inner race rings of the two ball bearings 34 ... A sprocket support 36 is connected via a buffer 37 to the left end of the wheel hub 33 and the drive sprocket 31 is attached to the support 36 of sprocket using multiple bolts 38 ... and nuts 39 ... Also, the sprocket support 36 is supported rotatably through a ball bearing 41 in an outer cylindrical wheel collar 40 surrounding the shaft 15 one end ending at an outer end of the inner race of the ball bearing 34 left, of the two ball bearings 34 ... For the oscillating arm 14a of the left side, a rear tie plate 42 having a cross section box connection ions 42a and 42b projecting from one side to the other from the swing arm 14a is welded to an outer surface of the inner raceway ring of a section corresponding to the gearwheel support 36, with a cylindrical spacer 44 surrounding the outer wheel collar 40 which is interposed between the rear tie plate 42 and an outer end of the inner race of the ball bearing 41 and an annular seal member 45 which is interposed between the sprocket support 26 and the spacer 44 on an outer side of the ball bearing 41. In this way, a gap between a left end of the wheel hub 33 of the rear wheel WR and the left swing arm 14a is kept constant and the penetration of dust and water is prevented, etc., from the left side to the wheel hub 33. On the other hand, a gap between a right end of the wheel hub 33 and the right rocker arm is also kept constant and the penis is prevented dust and water, etc., from the right side towards the wheel hub 33. The elongated holes 46, 46, 47 which are elongated in the longitudinal direction are respectively provided on the left and right sides of the rear ends of the swing arm left 14a and the rear tie plate 43 and the elongated holes (not shown) which are similar to the elongated holes 46 ... are also provided respectively on the left and right sides of the rear ends of the right swing arm. The left end of the shaft 15 and the outer wheel collars 40 ... which surround the left end of the shaft 15 fit into the elongated holes 46, 46, 47 of the left swing arm 14a and the rear tie plate 43, able to move in the longitudinal direction and the right end of the shaft 15 and an outer wheel collar surrounding the right end of the shaft 15 fit on the right swingarm, able to move in the longitudinal direction. The nuts 48 are threaded in the projecting sections of the outer wheel collars 40 ... from the rear end of the two swing arms 14a ... and the position of the shaft 15 along a longitudinal direction, mainly a longitudinal direction of the oscillating arms 14a ..., it is established constant by threading the nuts 48 ... in order to tighten the washers 49 between the outer surfaces of the rear end of the two oscillating arms 14a ... On the other hand, a head 15a extremely large contacting and meshing with an outer end of the left outer wheel collar 49 is integrally formed at the left end of the shaft 15 and although not shown in the drawings, the shaft is held between the rear end sections of the two oscillating arms 14a ... by screwing and tightening a nut having contact and meshing with the outer end of the right outer wheel collar at the right end of the tree 15.
In addition, the sliding guides 50 ... capable of sliding inside the oscillating arms 14a ... are fixed to the outer wheel collars 40 ... inside the two oscillating arms 14a ..., with the ends rear of the bolts 51 ... having the front ends connected to the slideways 50 ... being passed through the rear end walls of each swing arm 14a to be able to move in the axial direction and a pair of nuts 52 , 53 respectively threaded in the sections of the bolts 51 ... protruding from the rear wall of the oscillating arms 14a ... With the nuts 48 ... threaded, it is possible to adjust the tension of the chain 28 by adjusting the position of the shaft 15 in the longitudinal direction by loosening the nuts 52 and 53. Referring also to Figure 4, the upper and lower boxes 54 and 55 that enclose the swing arm 14a from above and below are attached to the left swing arm 14a of the fork. rear illa 14. The upper case 54 is formed so as to have a substantially U-shaped lateral cross section that opens downwardly joining a front plate 54 and a back plate 57 made by stamping a thin plate of steel and the bottom case 55 is formed so as to have a substantially U-shaped side cross section that opens upwardly joining a front plate 58 and a back plate 59 made by stamping a thin steel plate. In order to join the upper boxes 54 and lower
55, the rear tie plate 42 is welded to an inner outer surface of the swing arm 14a in a section corresponding to the gear rack 36 and a front tie plate 43 having box tie sections 43a and 43b extending upwardly and down from the swing arm 14a is welded to the inner outer surface of a part of the swing arm 14a towards the front end. The welding nuts 61 and 62 are fixed to the box joining sections 42a and 42b of the rear joining plate 42 and a lower rear section of the front plate 56 is attached to the box joining section 42a in order to cover the box joining section 42a from the outside by threading a pin 63 fixed through a lower rear section of the front plate 56 of the upper case 54 to the welding nut 61 and tightening it. Also, a rear upper section of the front plate 58 is attached to the box joining section 42b in order to cover the box joining section 42b from the outside by threading a bolt 64 fixed through a rear upper section of the plate front 58 of the lower case 55 to the welding nut 62 and squeezing it. Also, a front lower section of the front plate 56 is attached to the box joining section 43a in order to cover the box joining section 43a from the outside by threading a bolt 65 fixed through a lower front section to the plate front 56 of the upper case 54 to the welding nut (not shown) attached to the box joining section 43a of the front tie plate 43 and tightening it. In addition, a front upper section of the front plate 58 is attached to the box joining section 43b so as to cover the box joining section 43b from the outside by threading a bolt 66 fixed through the front upper section of the plate. front 58 of the bottom case 55 to a welding nut (not shown) attached to the box joining section 43b of the front tie plate 43 and tightening it. A substantially U-shaped cantilever 67 that opens upwards is welded to a rear upper surface of the swing arm 14a later than the rear tie plate 42 and a solder nut 68 is fixed to the interior of this bracket 67. Also, a lower end of the rear shock absorber 16 is inserted in the bracket 67 and the lower end of the rear shock absorber 16 is connected to a rear section of the swing arm 14a by threading a bolt 69 passed through the bracket 67 and the lower end of the rear shock absorber 16 to the welding nut 68 and squeezing it. The rear ends of the upper boxes 54 and lower 55 are connected together so that, for example, a rear end of the front plate 58 of the lower case 55 overlaps the inside of the front plate 56 of the upper case 54 and a rear end of the rear plate 59 of the lower case 55 overlaps the inside of the plate rear 57 of the upper case 54 and a rear connection section 70 for the upper 54 and lower 55 boxes is offset upwards from a central line C of the arm extending in the longitudinal direction of the swing arm 14a, along the axis of the shaft 15 for the rear wheel WR. In addition, the forward ends of the upper boxes 54 and lower 55 are disposed later than the rear end of the swing arm 14a and the rear end connection section 70 is arranged such that it is positioned higher when it moves towards the rear part. back In addition, upper boxes 54 and lower 55 are colored by coating or plating, but are also made of different colors to create a great contrast between upper boxes 54 and lower 55 and this mode are made of different colors so that the box upper 54 is a brighter color than lower case 55. For example, if upper case 54 becomes silver, lower case 55 becomes black. The oscillating arm 14a is also made silvery, for example, to be brighter than the lower case 55. In Figure 1 and Figure 2, in order to demonstrate that the lower case 55 is of a dark color, the bottom case 55 has been filled with dots, but this type of dotting does not indicate that the bottom case 55 is actually painted with dots. Then, in the description of the operation of this embodiment, a rear end connection section 70 of the upper boxes 54 and lower 55 enclosing the swing arm 14a from above and below being attached to the swing arm 14a of the rear fork 14 is arranged off center higher than a center line C of arm extending in a longitudinal direction of the swing arm 14a along the axis of the axle 15 of the rear wheel WR, which means that when the entire chain guard is made of the boxes upper 54 and lower 55 from the side, an external appearance is provided in such a way that the back of the chain guard rises in the back and it is possible to obtain an external appearance that improves the appearance of being lightweight, as much as a called guardacadena media. Also, a front end of the rear end connection section 70 for the upper case 54 and lower case 55 is disposed later than the rear end of the oscillating support 14 a, which means that the rear end of the lower case 55 is formed in order to curl up around the rear end of the swing arm 14a and it is possible to considerably improve the appearance of being of light weight. Also, it is possible to improve the ease of assembly by joining the upper case 54 to the swing arm 14a using the rear end of the lower case 55 as a guide section. Further, since the rear ends of the upper boxes 54 and lower 55 are connected together so that, for example, a rear end of the front plate 58 of the lower case 55 overlaps the inside of the front plate 56 of the case upper 54 and a rear end of the rear plate 59 of the lower case 55 overlap the inside of the rear plate 57 of the upper case 54, it is possible to hold the upper case 54 in the lower case 55 so as to simplify the action of joining the upper case 54 to the swing arm 14a, overlapping the rear end of the upper case 54 at the rear end of the lower case 55 after the union of the lower case 55 to the oscillating arm 14a and it is possible to further improve the ease of assembly with respect to the upper case 54 on the swing arm 14a. In addition, a claim characterized by the fact that the upper boxes 54 and lower 55 are made of different colors in order to increase the contrast between them is realized., by making the upper case 54 of a color brighter than the lower case 55, for example, in order to make the two boxes of different colors to increase the contrast between them, it is possible to obtain an external appearance with greater prestige. A modality of the present invention has been described in detail, however the present invention is not limited in this way and various design changes are possible without departing from the scope of the appended claims. For example, with the above-described embodiment, upper boxes 54 and lower 55 are formed of a thin steel plate, but it is also possible to respectively form upper and lower boxes using a synthetic resin. In this case, the coloration of the upper and lower boxes is not limited to the coating and it is also possible to economically carry out the new coating of a surface of the upper and lower boxes using a coloring agent or by performing the pleating. It is also possible to provide contrast by making the lower case 55 a brighter color than the upper case 54. According to the invention of claim 1, when the whole chain guard is viewed from the side, it is possible to obtain an external appearance where the part The back of the chain guard rises in the back and it is possible to obtain an external appearance that improves the appearance of being lightweight. According to the invention of claim 2, as well as being able to considerably improve the appearance of being of light weight, it is also possible to improve the ease of assembly by joining the upper box to the swing arm using the rear end of the box bottom as a guide section. According to the invention of claim 3, it is possible to obtain an external appearance with a more improved appearance of being of light weight.
Brief Description of the Drawings FIGURE 1 is a side elevational view of a motorcycle. FIGURE 2 is an elongated side view in elevation of a chain guard. FIGURE 3 is an elongated cross-sectional view along line 3-3 in Figure 2. FIGURE 4 is an elongated cross-sectional view along line 4-4 in Figure 2. 14a ... swing arm 15 shaft 54 upper case 55 lower case 70 rear end connection section C center line WR rear wheel