Title of Invention

EXHAUST SYSTEM SUPPORT STRUCTURE FOR MOTORCYCLE ENGINE

Abstract

(OBJECT) To reduce the number off the part and enable a reductiion in the number of the mounting steps in supporting an exhaust system. (Solving Means) The up streem end of a first exahust pipe 53 connecting between one end of an exhaust muffler 54, elongated in the width directiion of vehicle body frem 15 and 3 disposed between an engine E and reea wheel, and an exhaust port 51 is fastended to an engine body 22 on a staight line 59 connecting between a first center of gravity G2 of exhaust pipe 55 connected to the other end of the exhaust muffler 54 and the exhaust muffler 54 is supported on the vechicle body frame 15 at the second center of gravity G2.

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] PROVISIONAL/ COMPLETE SPECIFICATION [See Section 10] "EXHAUST SYSTEM SUPPORT STRUCTURE FOR MOTORCYCLE ENGINE" HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan The following specification particularly describes the nature of the invention and the manner in which it is to be performed :- The present invention relates to an exhaust system support structure for motorcycle engine. [Detailed Description of the Invention] "To ooi] [Technical Field to which the Invention Pertains] The present invention relates to an motorcycle in which an engine is mounted on a vehicle body frame on the front side of a rear wheel and an exhaust system comprising an exhaust muffler and connected to an exhaust 2. port provided in a main body of the engine is supported by the vehicle body frame, and particularly to an improvement in support structure of an exhaust system. [0002] [Prior Art] In a conventional motorcycle, generally, as disclosed for example in Japanese Patent Laid-open No. Hei 5-131963, an exhaust muffler of an exhaust system is elongated in the front-rear direction of the motorcycle and disposed on one side of the rear wheel, and an exhaust port of the engine to which the exhaust system is connected is disposed at a position near the center line of the vehicle body. [0003] [Problem to be Solved by the Invention] However, in supporting the conventional exhaust system on the vehicle body frame, the entire exhaust system is disposed on one side of the vehicle body center line and, therefore, the exhaust system must be rigidly supported on the vehicle body frame at a plurality of positions other than the portion where the exhaust system is connected to the engine body. Accordingly, the number of parts for supporting the exhaust system is large, and the number of steps for mounting the exhaust system on 3 the vehicle body frame is also large. [0004] The present invention has been made in consideration of the above-mentioned situations, and, accordingly, an object of the present invention is to provide an exhaust system support structure for engine in motorcycle by which the number of parts for supporting the exhaust system can be reduced and the number of steps for mounting the exhaust system can also be reduced. [0005] [Means for Solving the Problems] In order to attain the above object, the invention as set forth in claim 1 is characterized in that, in an motorcycle in which an engine is mounted, in front of a rear wheel (WR), on a vehicle body frame and an exhaust system including an exhaust muffler and connected to an exhaust port provided in an engine body of the engine is supported on the vehicle body frame, the exhaust muffler is elongated in the width direction of the vehicle body frame and disposed between the engine and the rear wheel, an upstream end of a first exhaust pipe connecting between one end of the exhaust muffler and the exhaust port is fastened to the engine body on a straight line connecting between a first center of gravity of the first 4 exhaust pipe and a second center of gravity of the exhaust muffler and a second exhaust pipe connected to the other end of the exhaust muffler, and the exhaust muffler is supported on" the vehicle body frame at the second center of gravity. [0006] With this configuration, the exhaust system is supported on a straight line passing through the center of gravity of the entire exhaust system by the main body of the engine mounted on the vehicle body frame and the vehicle body frame, whereby a bending load applied to the support portions for the exhaust system can be reduced, and the exhaust system can be supported with a sufficient support strength even though the exhaust system is supported at only two front and rear portions thereof. Besides, of the two portions, the support portion of the first exhaust pipe onto the engine body is a connection portion of the exhaust system to the engine body, so that the support portion exclusive for supporting the exhaust system is only the one portion where the exhaust muffler is supported on the vehicle body frame, whereby the number of parts for supporting the exhaust system can be reduced, and thereby the number of mounting steps can be reduced. 5 [0007] The invention as set forth in claim 2 is characterized, in addition to the configuration of the invention as set forth in claim 1, in that a drive chain for transmitting power from the engine to the rear wheel is disposed on one side of the vehicle body center line, and the first center of gravity of the first exhaust pipe and the second center of gravity of the exhaust muffler and the second exhaust pipe are disposed on the opposite side of the drive chain with respect to the vehicle body center line. According to this constitution, the exhaust muffler can be disposed as close as possible to the engine while obviating interference with the driving force transmission system between the engine and the rear wheel, the center of gravity can be lowered while maintaining a sufficient height from the ground, and mounting of the exhaust system can be facilitated. [0008] The invention as set forth in claim 3 is characterized, in addition to the configuration of the invention as set forth in claim 2, in that one end of the exhaust muffler is formed in a plane surface shape along a vertical plane and is disposed nearer to the vehicle body center line than the drive chain. According to this 6 constitution, the exhaust muffler can be disposed effectively on a lateral side of the space required for oscillation of the drive chain. [0009] [Mode for Carrying out the Invention] Hereinafter, a mode for carrying out the present invention will be described based on one embodiment of the invention shown in the accompanying drawings. [Brief Description of the Drawings] [FIG. 1] FIG. 1 is a side view of a motorcycle. [FIG. 2] FIG. 2 is an enlarged view of an essential part of FIG. 1. [FIG. 3] FIG. 3 is a vertical sectional side view showing the inside of a crankcase. [FIG. 4] FIG. 4 is a bottom view along arrow 4 of FIG. 2. [FIG. 5] FIG. 5 is a sectional view taken along line 5-5 of FIG. 2 7 [0010] FIGS. 1 to 5 show one embodiment of the invention, in which FIG. 1 is a side view of an motorcycle; FIG. 2 is an enlarged view of an essential part of FIG. 1; FIG. 3 is a vertical sectional side view for showing the inside of a crankcase, FIG. 4 is a bottom view along arrow 4 of FIG. 2, and FIG. 5 is a sectional view taken along line 5-5 of FIG. 2. [0011] First, in FIG. 1, a front fork 17 supporting a front wheel WF though a shaft is steerably turnably supported by a head pipe 16 provided at a front end of a vehicle body frame 15 of the automobile. A handlebar 18 is connected to the top end of the front fork 17, and a front fender 19 covering the upper side of the front 8 wheel WF is supported by the front fork 17. A rear fork 2 0 supporting a rear wheel WR though a shaft is turnably supported by a left-right pair of support brackets 40 fixed to an intermediate portion of the vehicle body frame 15, and a rear cushion 21 is provided between a rear portion of the vehicle body frame 15 and the rear fork 20. [0012] A water-cooled type engine E is mounted on an intermediate portion of the vehicle body frame 15, a main body 22 of the engine E and a radiator 24 supported by the vehicle body frame 15 are disposed on the front upper side of the engine body 22, and an air cleaner 23 supported by the vehicle body frame 15 is disposed on the front upper side of the engine body 22. In addition, a fuel tank 25 disposed on the rear upper side of the engine body 22 and a storage box 26 disposed on the rear upper side of the fuel tank 25 and so designed that electric parts can be contained therein are supported on the vehicle body frame 15. [0013] A font portion of the vehicle body frame 15, the engine E, the air cleaner 23 and the radiator 24 are covered by a synthetic resin-made leg shield 29 mounted to the vehicle body frame 15. A rear portion of the vehicle body frame 15, the fuel tank 25 and the storage box 26 are covered by a synthetic resin-made rear cover 30 mounted to the vehicle body frame 15, and a rear fender 31 covering the rear upper side of the rear wheel WR is provided adjacently to the rear cover 30. A seat 32 is provided on the rear cover 3 0 in such a condition that a top opening portion of the storage box 26 can be opened and closed, and a driver can be seated on the seat 32. [0014] In FIG. 2, the main body 22 of the engine E includes a cylinder block 34 having a cylinder bore 33 substantially extending along the front-rear direction of the vehicle body frame 15, a cylinder head 35 fastened to a front portion of the cylinder block 34, and a crankcase 36 fastened to a rear portion of the cylinder block 34, and the cylinder block 34 and the crankcase 36 are supported by support brackets 39, 4 0 ... fixed to the vehicle body frame 15. [0015] Referring to FIG. 3 as well, the crankcase 36 consists of left and right crankcase halves 37, 38 fastened to each other, and a crankshaft 41 is rotatably supported by the crankcase halves 37, 38. [0016] A transmission M is contained and disposed in the crankcase 36. The transmission M includes a main transmission shaft 42 to which power is transmitted from the crankshaft 41, an auxiliary transmission shaft 43 parallel to the main transmission shaft 42, gear trains 44 for a plurality of speed change stages provided between the main transmission shaft 42 and the auxiliary transmission shaft 43, and a shift mechanism 45 for selectively establishing one of the gear trains 44. [0017] The main transmission shaft 42 is rotatably supported by the crankcase 36 on the rear side of the crankshaft while having its axis line orthogonal to a substantially horizontal straight line 46 extending in the front-rear direction passing through the axis line of the crankshaft 41. The auxiliary transmission shaft 43 is rotatably supported by the crankcase 36 on the rear side of the main transmission shaft 42 while having its axis line orthogonal to the straight line 46. [0018] One end of the auxiliary transmission shaft 43 is projected to the outside penetrating through the left crankcase half 37 of the crankcase 36, a driving sprocket 47 is fixed to the projected one end portion of the auxiliary transmission shaft 43, and an endless drive chain 48 for transmitting power to the rear wheel WR is wound around the driving sprocket 47. [0019] A chain cover 49 for covering the wind-around bracket of the drive chain 48 onto the driving sprocket 47 is mounted to the outside surface of the left crankcase half 37. A chain cover 50 for covering the upper side of a portion of the drive chain 48 is mounted to the rear fork 20. [0020] Referring to FIG. 4 as well, an exhaust port 51 is provided at a side face of a lower portion of the cylinder head 3 5 in the engine body 22, and an exhaust system 52 is connected to the exhaust port 51. The exhaust system 52 is made up of a first exhaust pipe 53 whose upstream end is connected to the exhaust port 51, an exhaust muffler 54 disposed between the crankcase 36 of the engine E and the rear wheel and connected to the downstream end of the first exhaust pipe 53, and a second exhaust pipe 55 whose upstream end is connected to the exhaust muffler 54. [0021] The exhaust muffler 54 includes a casing 54a elliptical in transverse section, closed at both ends and elongated in the width direction of the vehicle body frame 15. A bottom wall rear portion 36a of the crankcase 36 corresponding to the main and auxiliary transmission shafts 42, 43 of the transmission M is formed to be higher than a bottom wall front portion 36b of the crankcase 36 corresponding to the crankshaft 41 in such a manner that a space for disposing at least a portion (in this embodiment, a portion) of the exhaust muffler 54 can be secured on the lower side of the bottom wall rear portion 36a. [0022] Since the bottom wall front portion 36b of the crankcase 36 is formed to be lower than the bottom wall rear portion 36a, an oil pool 56 is formed at a front portion of the inside of the crankcase 36 corresponding to the crankshaft 41, and a suction port 57 for sucking up the oil reserved in the oil sump 56 by a pump (not shown) is provided in the crankcase 36 adjacently to the bottom wall front portion 36b. [0023] The left and right crankcase halves 38, 39 which together constitute the crankcase 36 are provided with partition walls 58 curved correspondingly to a rotational locus of the outside surface of a crank weight 41a possessed by the crankshaft 41 in such a manner as to be closely opposed to each other at the time of coupling of the left and right crankcase halves 38, 39, and both of the partition walls 58 are formed to be intermediately disposed between the liquid surface L of the oil reserved in the oil sump 56 and the crank weight 41 of the crankshaft 41. [0024] Referring to FIG. 5 as well, the first exhaust pipe 53 of the exhaust system 52 is extended from the exhaust port 51 provided at a side wall of a lower portion of the cylinder head 35 on the right side of the vehicle body frame 15, is extended rearward on the right side of the vehicle body frame 15 on the lower side of the engine body 22, is extended on the lower side of the rear portion bottom wall 36a and bent to the left side of the vehicle body frame 15 at a portion corresponding to a rear portion of the crankcase 36, and the downstream end of the first exhaust pipe 53 is connected to one end of the exhaust muffler 54 on the left side of the vehicle body frame 15. The second exhaust pipe 55 is connected to the other end of the exhaust muffler 54, and is bent to be roughly L-shaped so that the downstream end thereof is directed rearwards. [0025] The first exhaust pipe 53, the exhaust muffler 54 and the second exhaust pipe 55 are so disposed that a straight line 59 connecting between a first center of gravity Gl of the first exhaust pipe 53 and a second center of gravity G2 of the exhaust muffler 54 and the second exhaust pipe 55 is close to and substantially parallel to the vehicle body center line 60, and the upstream end of the first exhaust pipe 52 is fastened to the cylinder head 35 of the engine body 22 with a plurality of sets of bolts 70 and nuts 71 on the straight line 59. A support stay 61 is fixed to an upper portion of the exhaust muffler 54, and, at a portion corresponding to the second center of gravity G2, the support stay 61 is fastened to a right support bracket 40 of a left-right pair of support brackets 40, 40 with a bolt 72 and a nut 73. Namely, the exhaust system 52 is supported on the vehicle body frame 15 at two positions, that is, the connection portion of the upstream end of the first exhaust pipe 53 to the cylinder head 35 and the support portion of the exhaust muffler 54 onto the support bracket 40. [0026] While the drive chain 48 for transmitting power from the engine E to the rear wheel WR is disposed on the left side of the vehicle body center line 60, the first center of gravity Gl of the first exhaust pipe 53 and the second center of gravity G2 of the exhaust muffler 54 and the second exhaust pipe 55 are located on the opposite side of the drive chain 48 with respect to the vehicle body center line 60, namely, on the right side of the vehicle body center line 60, and the straight line 59 connecting between the centers of gravity Gl and G2 is on the right side of and close to the vehicle body center line 60 and is substantially parallel with the vehicle body center line 60. [0027] One end of the exhaust muffler 54 is formed in a flat surface shape along a vertical plane, and is disposed nearer to the vehicle body center line 60 than the drive chain 48. [0028] A lower surface of the bottom wall rear portion 36a of the crankcase 36 is integrally provided with two sets of support bosses 62, 63 constituting pairs at left and right two positions, and a step holder 64 having left and 16 right ends raised up is fastened to the support bosses 62, 63. Steps 65, 65 are connected to the left and right ends of the step holder 64 so that they cart be folded up when not used. Since the bottom wall rear portion 36a of the crankcase 36 is disposed at a comparatively high position, the difference between the fastening position of the step holder 64 to the crankcase 36 and the position of the left and right steps 65, 65 may be comparatively small. Therefore, the rise-up amount of the Step holder 64 at the left and right ends can be made comparatively small, whereby strength load applied to the step holder 64 can be reduced, so that there is no need for reinforcing members or the like for the step holder 64, and the step holder 64 can be made small in weight. [0029] A stand support member 66 is fastened to a portion near the left end of the step holder 64, and a stand 67 for supporting the motorcycle in a stopped condition is connected to the stand support member 66 so that it can be sprung up. [0030] Now, the operation or function of this embodiment will be described. The bottom wall rear portion 36a of the crankcase 3 6 corresponding to the main and auxiliary 17 transmission shafts 42, 43 possessed by the transmission M contained and disposed in the crankcase 36 is formed to be higher than the bottom wall front portion 36b of the crankcase 36 so that a space for disposing at least a portion of the exhaust muffler 54 can be secured on the lower side of the bottom wall rear portion 36a. Therefore, the bottom of a front portion of the crankcase 36 can be made deeper than a rear portion thereof, whereby an oil can be reserved in a comparatively deep condition in a comparatively narrow space on the side of the front portion of the crankcase 36. With this arrangement, the oil can be efficiently sucked up by a simple suck-up structure while reducing as possible the amount of the oil reserved in the crankcase 36. [0031] In addition, since at least a portion of the exhaust muffler 54 is disposed on the lower side of the bottom wall rear portion 46a of the crankcase 36, the crankcase 36 is warmed by radiation heat from the exhaust muffler 54. And therefore, coupled with the comparative smallness of the amount of the oil, the oil is swiftly heated up, and warm-up performance of the engine E can be enhanced. [0032] The crankcase 36 is provided with the partition walls 58 curved correspondingly to a rotational locus of the outside surface of the crank weight 41a possessed by the crankshaft 41 so that the partition walls 58 are disposed intermediately between the liquid level L of the oil reserved in the oil sump 56 formed at a front portion in the crankcase 36 correspondingly to the crankshaft 41 and the crank weight 41a. And therefore, agitation of the oil by the crank weight 41a is obviated as possible, and it is possible to improve fuel efficiency through reduction of friction loss of the engine E. [0033] The exhaust muffler 54 is elongated in the width direction of the vehicle body frame 15 and disposed between the engine E and the rear wheel WR, the upstream end of the first exhaust pipe 53 is fastened to the cylinder head 35 of the engine body 22 on the straight line 59 connecting between the first center of gravity Gl of the first exhaust pipe 53 connecting between one end of the exhaust muffler 54 and the exhaust port 51 of the cylinder head 35 and the second center of gravity G2 of the exhaust muffler 54 and the second exhaust pipe 55 connected to the other end of the exhaust muffler 54, and the exhaust muffler 54 is supported on the vehicle body frame 15 at the second center of gravity G2. [0034] Namely, the exhaust system 52 is supported by the main body 22 of the engine E mounted on the vehicle body frame 15 and the vehicle body frame 15 on the straight line 59 passing through the center of gravity of the entire exhaust system 52, whereby a bending load acting on the support portions of the exhaust system 52 is reduced, and the exhaust system 52 can be supported with sufficient support strength even though the exhaust system 52 is supported at only front and rear two positions. [0035] Besides, of the above-mentioned two positions, the support portion of the first exhaust pipe 53 onto the cylinder head 35 is a connection portion of the exhaust system 52 to the engine body 22, and therefore, the exclusive support portion for supporting the exhaust system 52 is the one portion at which the exhaust muffler 54 is supported on the vehicle body frame 15. In addition, the support stay 61 fixed to the exhaust muffler 54 is fastened to one of a pair of the support brackets 40 for supporting the main body 22 of the engine E onto the vehicle body frame 15, whereby the exhaust muffler 54 is supported onto the vehicle body frame 15, namely, one of the brackets 40 is used in common for two functions. And therefore, the number of parts for supporting the exhaust system 52 is reduced, and the number of mounting steps can be reduced accordingly. [0036] In addition, the drive chain 48 for transmitting power from the engine E to the rear wheel WR is disposed on the left side of the vehicle body center line 60, while the first center of gravity Gl of the first exhaust pipe 53 and the second center of gravity G2 of the exhaust muffler 54 and the second exhaust pipe 55 are disposed on the opposite side of the drive chain 48 with respect to the vehicle body center line 60; and therefore, the exhaust muffler 54 can be disposed as close as possible to the engine E while obviating interference with the driving force transmission system between the engine E and the rear wheel WR; the center of gravity can be set lower while securing a sufficient height from the ground, and mounting of the exhaust system 52 is facilitated. [0037] Furthermore, since one end of the exhaust muffler 54 is formed in a flat surface shape along a vertical 21 plane and disposed nearer to the vehicle body center line 60 than the drive chain 48, the exhaust muffler 54 can be effectively disposed on a lateral side of the space required for oscillation of the drive chain 48. [0038] While the embodiment of the present invention has been described above, the invention is not limited to or by the above embodiment, and various design modifications can be made without departure from the invention as set forth in claims. [0039] For example, while the engine E is a four-cycle engine in the embodiment, the invention can be applied also to an exhaust system of a two-cycle engine mounted on a motorcycle. [0040] [Effect of the Invention] As described above, according to the invention as set forth in claim 1, the exhaust system is supported on the engine mounted on the vehicle body frame and the vehicle body frame on the straight line passing through the center of gravity of the entire exhaust system, whereby a bending load acting on the support portions of the exhaust system can be reduced, and the exhaust system can be supported with a sufficient support strength even though the exhaust system is supported at front and rear two positions. In addition, the exclusive support portion for supporting the exhaust system is the one portion where the exhaust muffler is supported on the vehicle body frame, so that the number of parts for supporting the exhaust system can be reduced, and the number of mounting steps can be reduced accordingly. [0041] Besides, according to the invention as set forth in claim 2, the exhaust muffler can be disposed as close as possible to the engine while obviating interference with the driving force transmission system between the engine and the rear wheel, the center of gravity can be set lower while securing a sufficient height from the ground, and mounting of the exhaust system is facilitated. [0042] Furthermore, according to the invention as set forth in claim 3, the exhaust muffler can be effectively disposed on a lateral side of the space required for oscillation of the drive chain. 23 WE CLAIM: 1 An exhaust system support structure for a motorcycle engine in which an engine (E) is mounted, in front of a rear wheel (WR), on a vehicle body frame (15), and an exhaust system (52) including an exhaust muffler (54) and connected to an exhaust port (51) provided in an engine body (22) of said engine (E) is supported on said vehicle body frame (15), characterized in that, said exhaust muffler (54) is elongated in the width direction of said vehicle body frame (15) and disposed between said engine (E) and said rear wheel (WR) , an upstream end of a first exhaust pipe (53) connecting between one end of said exhaust muffler (54) and said exhaust port (51) is fastened to said engine body (22) on a straight line (59) connecting between a first center of gravity (Gl) of said first exhaust pipe (53) and a second center of gravity (G2) of said exhaust muffler (54) and a second exhaust pipe (55) connected to the other end of said exhaust muffler (54), and said exhaust muffler (54) is supported on said vehicle body frame (15) at said second center of gravity (G2). 2 An exhaust system support structure for a motorcycle engine as claimed in claim 1, wherein a drive chain (48) for transmitting power from said engine (E) to said rear wheel (WR) is disposed on one side of a vehicle body center line (60), and said first center of gravity (Gl) of said first exhaust pipe (53) and said second center of gravity (G2) of said exhaust muffler (54) and said second exhaust pipe (55) are disposed on the opposite side of said drive chain (48) with respect to said vehicle body center line (60). 3 An exhaust system support structure for a motorcycle engine as claimed in claim 2, wherein One end of said exhaust muffler (54) is formed in a flat surface shape along a vertical plane and is disposed nearer to said vehicle body center line (60) than said drive chain (48).

Documents:

645-mum-2001-abstract(11-5-2007).pdf

645-mum-2001-cancelled pages(11-5-2007).pdf

645-mum-2001-claims(granted)-(11-5-2007).pdf

645-mum-2001-correspondence(11-5-2007).pdf

645-mum-2001-correspondence(ipo)-(31-1-2007).pdf

645-mum-2001-drawing(11-5-2007).pdf

645-mum-2001-form 1(11-5-2007).pdf

645-mum-2001-form 18(13-6-2005).pdf

645-mum-2001-form 2(granted)-(11-5-2007).pdf

645-mum-2001-form 3(11-5-2007).pdf

645-mum-2001-form 5(11-5-2007).pdf

645-mum-2001-petition under rule 137(11-5-2007).pdf

645-mum-2001-petition under rule 138(11-5-2007).pdf

645-mum-2001-power of authority(11-5-2007).pdf

645-mum-2001-power of authority(31-10-2001).pdf

645-mumnp-2001-claims(granted)-(11-5--2007).doc

645-mumnp-2001-form 2(granted)-(11-5--2007).doc

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