Title of Invention

"MUFFLER MOUNTING STRUCTURE"

Abstract

A muffler mounting structure comprising: a supporting bracket unit used for mounting a muffler 35 to a power unit 30 which has an engine 31 and a transmission for transmitting an output of the engine 31 to a rear wheel 27 and which is swingably mounted on a vehicular body 2: wherein said supporting bracket unit comprises a first supporting bracket 41 mounted to said power unit 30 and a second supporting bracket 50 mounted to said muffler 35; said first supporting bracket 41 has an extension portion 48 which is bent outward of the vehicle at a position "a" in such a manner as to be in parallel to the muffler 35, said extension portion 48 floating from said muffler 35 so as to extend rearwards to a position where the gravity of said muffler 35 is located; and said second supporting bracket 50 has a second connecting portion 55 which is in parallel to said extension portion 48, said extension portion 48 being connected at a rear end thereof to said connecting portion 55 so as to support said muffler 35 at the rear end of said extension portion 48 around which the gravity of said muffler 35 is located.

Full Text

The present invention relates to a muffler mounting structure used for a motorcycle of a type in which a power unit is mounted. [0002] [Prior Art] In motorcycles of a type in which a power unit including an engine and a transmission for transmitting an output of the engine to a rear wheel is swingably mounted to a body frame, a muffler swinging together with the engine is mounted not on the body side but on the power unit side. Methods of mounting of such a muffler have been known, for example, from Japanese Patent Laid-open No. Sho 63-176614 entitled "Structure for Supporting Exhaust System of Unit Swing type Engine". With reference to Figs. 7 and 8 equivalent to Figs. 1 and 2 of the above gazette, the prior art structure will be described. In Figs. 7 and 8 in this specification, parts corresponding to those in Figs. 1 and 2 in the above gazette are indicated by different reference numerals. [0003] Fig. 7 is a side view of the prior art muffler mounting structure. A muffler mounting structure 100 includes a supporting bracket 103 for mounting a muffler 102 to a crank case of an engine main body 101 and an elastic bush 110 (this will be described with reference to Fig. 8) for mounting the supporting bracket 103 in a floating manner. The supporting bracket 103 formed in a flat shape has the front end mounted on bosses 106 and 107 of the crack case with bolts 104 and 105 respectively and the lower end welded to the front end of the muffler 102. Reference numeral 108 indicates an exhaust pipe, and 109 is a fan cover. [0004] Fig. 8 is a sectional view taken on line 8-8 of Fig. 7. The elastic bush 110 includes an inner cylinder 111 mounted to the boss 107 with the bolt 105, a rubber made damping cylinder 112 inserted around the inner cylinder 111, and an outer cylinder 113 fitted between the rubber damping cylinder 112 and a collar 103a. The collar 103a is welded to the supporting bracket 103. [0005] [Problem to be solved by the Invention] Although the muffler 102 shown in Fig. 7 is disposed in parallel to the body, a different muffler projecting obliquely, rearward from the vehicle in a plan view is sometimes used. Such a muffler is difficult to be mounted using the flat supporting bracket 103 shown in Fig. 7. A supporting bracket for mounting such a bracket will be described below. [0006] Fig. 9 is a side view of a prior art muffler supporting bracket. A supporting bracket 115 has an arm portion 115a and a mounting portion 115b. The arm portion 115a rises from a position "a" in the rising direction shown by an arrow © with respect to an axis 116 extending in parallel to the center of the vehicle, and bends from a bending position "b" in the direction (projecting outward of the vehicle) shown by an arrow (2). The mounting portion 115b bends from a bending position "c" in the direction shown by an arrow (3). The muffler 118 is mounted to the crank case 117 by mounting the front end of the supporting bracket 115 to the crank case 117 and also mounting the mounting portion 115b of the supporting bracket 115 to an outer periphery 118a of the muffler 118. [0007] The muffler 118 projecting obliquely, rearward from the vehicle can be thus mounted to the crank case 117 using such a supporting bracket 115. However, the supporting bracket 115 having a complicated structure is not usually adopted, and instead the simple supporting bracket 103 shown in Fig. 7 is used. The use of the supporting bracket 103 restricts the arrangement of the muffler 118 and reduces the degree of freedom in design. [0008] On the other hand, it is desirable to support the muffler 118 shown in Fig. 9 at a position corresponding to the gravity G or in the vicinity thereof. To meet such a requirement, the arm portion 115a of the supporting bracket 115 must be extended, so that the shape of the supporting bracket 115 becomes more complicated. Accordingly, it is difficult to support the muffler 118 at a position corresponding to the gravity G or in the vicinity thereof. [0009] An object of the present invention is to provide a technique capable of enhancing the degree of freedom in design with respect to arrangement of a muffler and of easily supporting the muffler at a position corresponding to the gravity or in the vicinity thereof. [0010] [Means for Solving the Problem] To achieve the above object, according an invention described in claim 1, there is provided a muffler mounting structure including: a supporting bracket unit used for mounting a muffler to a power unit including an engine and a transmission for transmitting an output of the engine to a rear wheel and being swingably mounted on a vehicular body; wherein the supporting bracket unit includes a first supporting bracket mounted to the power unit and a second supporting bracket mounted to the muffler; the first supporting bracket has an extension portion extending in parallel to the muffler in a plan view and the second supporting bracket has a connection portion parallel to the extension portion in a plan view; and the extension portion is connected to the connection portion. [0011] The extension portion of the first supporting bracket can be formed only by bending the first supporting bracket outward of the vehicle and the connection portion of the second supporting bracket can be formed only by bending the second supporting bracket in the vertical direction. Accordingly, the first and second supporting brackets can be easily manufactured at a low cost. Although each of the first and second supporting brackets is simple in its shape, the combination of these supporting brackets can constitute a complex supporting unit capable of being matched with arrangements of various ? i mufflers* [0012] According to an invention described in claim 2, the above second supporting bracket is mounted on the muffler at a position corresponding to the gravity or in the vicinity thereof. The extension portion of the first supporting bracket is not welded to the muffler and floated from the muffler, so that the rear end of the extension portion can support the muffler at a position corresponding to the gravity or in the vicinity thereof. Accordingly, it becomes possible to eliminate the need of supporting the leading end of the muffler in a cantilevered manner as in the prior art muffler supporting structure, and hence to mount the muffler in a stable state. [Brief Description of the Drawings] [Fig. 1] A side view of a scooter type motorcycle including a muffler mounting structure of the present invention. [Fig. 2] A perspective view of a power unit of the present invention. [Fig. 3] A side view of a muffler mounting structure of the present invention. [Figs. 4(a) to 4(c)] Figs. 4(a) to 4(c) are sectional views taken on lines A-A, B-B and C-C of Fig. 3. [Fig. 5] A plan view of the muffler mounting structure of the present invention. [Fig. 6] A view illustrating a procedure of mounting the muffler mounting structure of the present invention. [Fig. 7] A side view of a prior art muffler mounting structure. [Fig. 8] A sectional view taken on line 8-8 of Fig. 7. [Fig. 9] A side view of a prior art muffler supporting bracket. Accordingly there is provided a muffler mounting structure comprising: a supporting bracket unit used for mounting a muffler to a power unit which has an engine and a transmission for transmitting an output of the engine to a rear wheel and which is swingably mounted on a vehicular body: wherein said supporting bracket unit comprises a first supporting bracket mounted to said power unit and a second supporting bracket mounted to said muffler; said first supporting bracket has an extension portion which is bent outward of the vehicle at a position "a" in such a manner as to be in parallel to the muffler, said extension portion floating from said muffler so as to extend rearwards to a position where the gravity of said muffler is located; and said second supporting bracket has a second connecting portion which is in parallel to said extension portion, said extension portion being connected at a rear end thereof to said connecting portion so as to support said muffler at the rear end of said extension portion around which the gravity of said muffler is located. [0013] [Preferred Embodjjnents of the Invention] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the drawings should be viewed in the direction of characters. Fig. 1 is a side view of a scooter type motorcycle including a muffler mounting structure of the present invention. A scooter type motorcycle 1 includes a body frame 2, a body cover 10 covering the body frame 2, a front wheel 25, a rear wheel 27, a power unit 30 supporting the rear wheel 27, and a muffler mounting structure 45 for mounting a cylindrical muffler 35 to the power unit 30. In addition, the muffler mounting structure 45 will be described in detail with reference to Figs. 3 to 5. Reference numeral 9a indicates a seat; and 9b is a spare tire which is mounted to a rear portion of the body frame 2 with a rear carrier 9c and a support 9d. [0014] The body frame 2 includes a head pipe 3, a front fork 4 operably supported on the head pipe 3, a handlebar 5 connected to the front fork 4, a down tube 6 extending rearward, downward from the head pipe 3, and a rear frame 7 extending rearward from the lower end of the down tube 6. The front wheel 25 is suspended from the lower end portion of the front fork 4. [0015] The rear frame 7 has an elliptic shape in a plan view, which includes a pair of right and left front frame portions 7a (only one is shown in the figure) extending rearward from the lower end of the down tube 6 substantially in the horizontal direction, a pair of right and left intermediate frame portions 7b (only one is shown in the figure) extending rearward, upward from the rear portions of the front frame portions la, and a rear frame portion 7c connecting the rear ends of the intermediate frame portions 7b to each other. [0016] The body cover 10 includes a front cover 11 and a front side cover 12 respectively covering the front portion of the head pipe 3 and the upper portion of the front wheel 25, a handlebar cover 13 covering the periphery of the handlebar 5, a leg shield 14 covering a portion in front of the leg portion of the driver, a front panel 15 supporting the feet of the driver, a center cover 16 covering the front portions of the intermediate frame portions 7b, a side cover 17 and an under cover 18 covering both the side surfaces of the rear portion of the body frame 2, and a rear upper cover 19 covering a rear, upper portion of the body frame 2- Reference numeral 20 indicates a rear fender disposed behind the side cover 17, which covers the upper portion of the rear wheel 27. [0017] Fig. 2 is a perspective view of the power unit of the present invention, seen from the rear side of the motorcycle of Fig. 1. The power unit 30 includes a two cycle forced-air cooled engine 31 and a continuously variable transmission (only a transmission case 32 is shown in the figure) for transmitting an output of the engine 31 to the rear wheel 27. The power unit 30 is swingably mounted to the rear frame 7 shown in Fig. 1 via hangers 33, 33 mounted to hanger brackets (not shown). Reference numeral 35 indicates a cylindrical muffler, which is positioned on the side opposite to the power unit 30. [0018] Fig. 3 is a side view of the muffler mounting structure of the present invention. A muffler mounting structure 40 includes a first supporting bracket 41 mounted to a crank case 44 of the power unit 30, and a second supporting bracket 50 mounted to the cylindrical muffler 35. The first supporting bracket 41, which is formed of a stay plate 42 and a channel-shaped reinforcing plate 43 (this will be described with reference to Fig. 4(b)) welded on the back surface of the stay plate 42, includes a crank case mounting portion 47 mounted on upper and lower bosses 45, 46 of the crank case 44, an extension portion 48 extending rearward along the inclination of the cylindrical muffler 35, and a first connection portion 49 provided at the rear end of the extension portion 48. [0019] The second supporting bracket 50, which is formed by overlapping and welding an inner stay plate 51 and an outer stay plate 52 to each other (see Fig. 4(c)), includes leg portions 53, 53 welded on the outer periphery of the cylindrical muffler 35, and a second connection portion 55 connected to the first connection portion 49 via a bolt 54. The leg portions 53, 53 are formed by bending the lower end portions of the inner and outer stay plates 51, 52 in such a manner as to be brought in contact with the outer periphery of the cylindrical muffler 35. The second connection portion 55 has a slot 55a into which the bolt 54 is to be inserted. Reference numeral 31a indicates a cylinder; 35a is an exhaust tube; and 57 is a fan cover. [0020] Figs. 4(a) to 4(c) are sectional views taken on lines A-A, B-B, C-C of Fig. 3, respectively. Fig. 4(a) shows an upper portion of the crank case mounting portion 47. The upper portion of the crank case mounting portion 47 is so configured that an upper collar 58 is welded between the stay plate 42 and the reinforcing plate 43, and is mounted to the upper boss 45 of the crank case 44 with a bolt 60. A lower portion of the crank case mounting portion 47 is so configured that a lower collar 58 is welded between the stay plate 42 and the reinforcing plate 43, and is similarly mounted to the lower boss 46 of the crank case 45. [0021] Fig. 4(b) shows the extension portion 48, which has a recessed portion 42a in the surface of the stay plate 42. The reinforcing plate 43 is formed in a channel-shape in vertical cross-section, and has upper and lower bent portions welded to upper and lower edges of the back surface of the stay plate 42. [0022] Fig. 4(c) shows a state in which the first and second connection portions 49, 55 are connected to each other. The first connection portion 49 includes a collar 59 welded to the stay plate 42 and the reinforcing plate 43, the collar 59 having a threaded hole. The second connection portion 55 is raised in the vertical direction by welding the leg portions 53, 53 of the inner and outer stay plates 51, 52 around the outer periphery of the cylindrical muffler 35, and is mounted to the first connection portion 49 via the bolt 54. Reference numeral 4la indicates a mounting surface of the first supporting bracket 41, which is formed of the upper and lower bosses 45, 46. [0023] Fig. 5 is a plan view of the muffler mounting structure of the present invention. The first supporting bracket 41 is so configured that the extension portion 48 is bent outward of the vehicle at a position "a" in such a manner as to be in parallel to the cylindrical muffler 35 in a plan view. The second supporting bracket 50 is so configured that the second connecting portion 55 is in parallel to the extension portion 48 in a plan view. The second supporting bracket 50 includes the leg portions 53, 53 of the inner and outer stay plates 51, 52, which are bent in the vertical direction. [0024] A procedure of mounting the muffler mounting structure of the present invention will be described below. Fig. 6 is a view illustrating the procedure of mounting the muffler mounting structure of the present invention. First, the leg portions 53, 53 of the second supporting bracket 50 are welded on the outer periphery of the cylindrical muffler 35 in parallel to the cylindrical muffler 35 as shown by an arrow (J), and the second connection portion of the second supporting bracket 50 is disposed in parallel and vertical to the cylindrical muffler 35. [0025] Next, the leading end of the exhaust tube 35a is mounted on the cylinder 31a in a manner shown by an arrow (D, and fastened thereto by means of the bolts 60, 60 in a manner shown by an arrow (3) so that the crank case mounting portion 47 of the first supporting bracket 41 is mounted on the upper and lower bosses 45, 46 (boss 46 is shown in Fig. 3) of the crank case 44. Thus, the extension portion 48 is rendered in parallel to the cylindrical muffler 35 and the first connection portion 49 at the rear end of the extension portion 48 is positioned in the vicinity of the second connection portion 55 in parallel to the second connection portion 55. Next, the bolt 54 is made to pass through the slot 55a of the second connection portion 55 in a manner shown by an arrow @ to be screwed with the female-threaded hole of the collar 59. Thus, the first connection portion 49 is connected to the second connection portion 55, so that the first supporting bracket 41 and the second supporting bracket are assembled into one-body. [0026] In this way, since the supporting bracket unit is divided into a first supporting bracket 41 and the second supporting bracket 50, it can be formed into a complex shape by combination of the brackets 41 and 50 each of which is formed into a simple shape. Accordingly, it is possible to easily manufacture a complex supporting bracket unit, and hence to increase the degree of freedom in design with respect to arrangement of the cylindrical muffler 35. [0027] In the muffler mounting structure 40 of the present invention, since the extension portion 48 of the first supporting bracket 41 is not welded to the cylindrical muffler 35 and is floated therefrom, the rear end of the extension portion 48 can support the cylindrical muffler 35 at a position corresponding to the gravity G or in the vicinity thereof (see Figs. 3 and 5). Accordingly, since the leading end of the muffler is not required to be supported in a cantilevered manner as in the prior art muffler mounting structure, the cylindrical muffler 35 can be stably mounted. Moreover, by floating the extension portion 48 from the cylindrical muffler 35, vibration of the engine 31 can be absorbed by the extension portion 48. Accordingly, each supporting bracket is not required to be mounted via a rubber member as in the prior art muffler mounting structure. [0028] In the above embodiment, as shown in Fig. 3, the crank case mounting portion 47 of the first supporting bracket 41 is mounted at two positions by means of the bolts; however, it may be fixed only at one position by means of the bolt, and rotation-stopped at the other position. Moreover, although in the previous embodiment, the first and second supporting brackets 41 and 50 are fixed by means of the bolts as shown in Fig. 3, they may be connected to each other by means of other means such as rubber mounting, welding or insertion. [0029] [Effect of the Invention] The invention having the above configuration has the following effects. According to the invention described in claim 1, since the extension portion of the first supporting bracket can be formed only by bending the first supporting bracket outward of the vehicle and the connection portion of the second supporting bracket can be formed only by bending the second supporting bracket in the vertical direction, the first and second supporting brackets^can be easily manufactured at a low cost. Although each of the first and second supporting I ? brackets is simple in its shape, thejcombination of thes« supporting brackets can constitute a-complex supporting unit capable of being matched with arrangements of various mufflers. Accordingly, it is possible to enhance the degree of freedom in design with respect to arrangement of the muffler. [0030] According to the invention described in claim 2, the extension portion of the first supporting bracket is, not welded to the muffler and floated therefrom, so that the rear end of the extension portion can support the muffler at a position corresponding to the gravity or in the vicinity thereof. Accordingly, it becomes possible to eliminate the need of supporting the leading end of the muffler in a cantilevered manner as in the prior art muffler supporting structure, and hence to mount the muffler in a stable state. Moreover, by floating the extension portion from the muffler, vibration of the engine can be absorbed by the extension portion. Accordingly, each supporting bracket is not required to be mounted via a rubber member as in the prior art. [Reference Characters] 2: body frame (body), 27: rear wheel, 30: power unit, 31: engine, 35: muffler (cylindrical muffler), 40: muffler mounting structure, 41: first supporting bracket, 48: extension portion, 50: second supporting bracket, 55: second connection portion (connection portion), G: gravity Fig. 9 forward backward WE CLAIM:- 1. A muffler mounting structure comprising: a supporting bracket unit 40 used for mounting a muffler 35 to a power unit 30 which has an engine 31 and a transmission for transmitting an output of the engine 31 to a rear wheel 27 and which is swingably mounted on a vehicular body 2: wherein said supporting bracket unit 40 comprises a first supporting bracket 41 mounted to said power unit 30 and a second supporting bracket 50 mounted to said muffler 35; said first supporting bracket 41 has an extension portion 48 arranged in parallel to said muffler 35, said extension portion 48 floating from said muffler 35 so as to extend rearwards to a position where the gravity of said muffler 35 is located; and said second supporting bracket 50 has a connection portion 55 parallel to said extension portion 48 in a plan view, said extension portion 48 being connected at a rear end thereof to said connecting portion 55 so as to support said muffler 35 at the rear end of said extension portion 48 around which the gravity of said muffler 35 is located. 2. A muffler mounting structure substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

404-del-1997-abstract.pdf

404-DEL-1997-Claims.pdf

404-del-1997-correspondence-others.pdf

404-del-1997-correspondence-po.pdf

404-DEL-1997-Description (Complete).pdf

404-del-1997-drawings.pdf

404-del-1997-form-1.pdf

404-del-1997-form-13.pdf

404-del-1997-form-19.pdf

404-del-1997-form-2.pdf

404-del-1997-form-3.pdf

404-del-1997-form-4.pdf

404-del-1997-form-5.pdf

404-del-1997-form-6.pdf

404-del-1997-gpa.pdf

404-del-1997-petition-137.pdf

404-del-1997-petition-138.pdf

404-del-1997-petition-others.pdf

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