Title of Invention

INTERNAL COMBUSTION ENGINE AND MOTORCYCLE

Abstract To provide an internal combustion engine which exhibits an excellent soundproof effect and an excellent cooling effect. [Means for Resolution] In an air-cooled internal combustion engine 50 which closes an upper end of a cylinder block 52 with a cylinder head 53 thus forming a combustion chamber 63 inside the cylinder block and a cylinder head cover 54 is mounted on the cylinder head 53, an outer peripheral portion of the cylinder head cover 54 has the duplicate structure which is constituted of a first longitudinal wall 87 and a second longitudinal walls 88, the first longitudinal wall 87 and the second longitudinal walls 88 are connected with each other by ribs, a cavity 98 is formed between the first longitudinal wall 87 and the second longitudinal walls 88, and the cavity 98 has a lower side thereof opened, and the cylinder head cover 54 includes a guide portion which guides a traveling wind which flows in the cavity 98 in a state that the traveling wind is directed toward the ignition plug 64. [Selected Drawing] Fig. 5
Full Text

[Designation of Document] Specification
[Title of the Invention] INTERNAL COMBUSTION ENGINE AND MOTORCYCLE
[Technical Field]
[0001]
The present invention relates to an internal combustion engine and a motorcycle which mounts the internal combustion engine thereon.
[Background Art]
[0002]
Cooling is extremely important in an internal combustion engine and hence, with respect to an air-cooled internal combustion engine, there has been known an internal combustion engine which enhances a cooling effect by forming cooling fins on a cylinder head cover (for example, see Patent Document 1) . [Patent Document 1] JP-UM-A-63-196451
[Disclosure of the Invention]
[Problems that the Invention is to Solve]
[0003]
However, the cooling fins of the cylinder head cover have only a function of a heat radiation plate and do not have other functions.
Since the cooling fins of the cylinder head cover are arranged in parallel to cooling fins of a cylinder block and hence, it is merely possible to obtain an extremely limited

advantageous effect which is referred to as the enhancement of a cooling effect by increasing a heat radiation area. For example, although the cooling of a plug mounting portion in the periphery of a combustion chamber is extremely important in the internal combustion engine, the mere formation of the cooling fins on the cylinder head cover is not sufficient to positively cool the above-mentioned particular portion. [0004]
Further, in the conventional cylinder head cover provided with the cooling fins, attachments having the cooling fins are formed as parts separate from the cylinder head cover and these attachments are mounted on the cylinder head cover by way of a rubber gasket for preventing resonance and hence, the number of parts is increased and, at the same time, the number of men-hours is increased thus pushing up a cost.
Accordingly, it is an object of the present invention to provide an internal combustion engine which exhibits an excellent soundproof effect and an excellent cooling effect as well as a motorcycle which mounts such an internal combustion engine thereof.
[Means for Solving the Problem] [0005]
To solve the above-mentioned problems, the invention according to claim 1 is characterized in that an air-cooled internal combustion engine (for example, an engine 50 in an

embodiment described later) which closes an upper end of a cylinder block (for example, a cylinder block 52 in the embodiment described later) with a cylinder head (for example, a cylinder head 53 in the embodiment described later) thus forming a combustion chamber (for example, a combustion chamber 63 in the embodiment described later) inside the cylinder block and a cylinder head cover (for example, a cylinder head cover 54 in the embodiment described later) is mounted on the cylinder head, wherein an outer peripheral portion of the cylinder head cover has the duplicate structure which is constituted of double longitudinal walls (for example, a first longitudinal wall 87 and a second longitudinal wall 88 in the embodiment described later).
By constituting the internal combustion engine in this manner, the outer peripheral portion of the cylinder head cover is constituted of the duplicate structure and hence, it is possible to enhance a soundproof effect. Further, a heat radiation area of the cylinder head cover is increased thus enhancing a cooling effect. [0006]
The invention according to claim 2 is, in the invention described in claim 1, characterized in that the double longitudinal walls are connected with each other by ribs (for example, ribs 94 in the embodiment described later).
By constituting the internal combustion engine in this

manner, it is possible to ensure strength of the duplicate structure portion with use of the ribs and hence, the longitudinal walls can be made thin thus enabling the reduction of weight of the cylinder head cover.
The invention according to claim 3 is, in the invention described in claim 1, characterized in that a space defined between the double longitudinal walls has a lower side thereof opened and an upper side thereof closed.
By constituting the internal combustion engine in this manner, it is possible to further reduce the weight of the cylinder head cover. Further, since it is possible to allow air to flow into and to flow out from the space defined between the double longitudinal walls, the cooling effect is enhanced. [0007]
The invention according to claim 4 is, in the invention described in claim 3, characterized in that the cylinder head cover includes a recessed portion (for example, a recessed portion 91 in the embodiment described later) on an upper extension of an ignition plug (for example, an ignition plug 64 in the embodiment described later) which is mounted on the cylinder head and also includes a guide portion (for example, a closing wall 92F in the embodiment described later) which guides a traveling wind which flows in a space defined between the double longitudinal walls in a state that the traveling wind is directed toward the ignition plug.

By constituting the internal combustion engine in this manner, the traveling wind flows toward the ignition plug thus effectively cooling the combustion chamber in the periphery of the ignition plug mounting portion. [0008]
The invention according to claim 5 is directed to a motorcycle which is characterized by mounting the internal combustion engine described in claim 4 thereon and by arranging the cylinder block of the internal combustion engine to be inclined forwardly toward a front side of a vehicle body.
By constituting the motorcycle in this manner, a traveling wind which flows in a space defined between the double longitudinal walls easily impinges on the ignition plug thus effectively cooling the internal combustion engine of the motorcycle.
[Advantage of the Invention] [0009]
The invention according to claim 1 can enhance a soundproof effect and a cooling effect of the internal combustion engine. Further, the merchantability of appearance of the cylinder head cover can be improved and the cooling performance around the plug can be improved without adopting the complicated structure.
The invention according to claim 2 or claim 3 can reduce the weight of the cylinder head cover and can reduce the weight

of the internal combustion engine. Further, the invention according to claim 3 can also improve the cooling effect.
The invention according to claim 4 can effectively cool the combustion chamber in the periphery of the ignition plug mounting portion.
The invention according to claim 5 can effectively cool the internal combustion engine of the motorcycle. [Best Mode for carrying out the Invention] [0010]
Hereinafter, an embodiment of an internal combustion engine and a motorcycle according to the present invention is explained in conjunction with Fig. 1 to Fig. 6. Here, in the explanation made hereinafter, the directions such as front, rear, left, right and the like are, unless otherwise specified, identical with corresponding directions of a vehicle . Further, in the figures, an arrow FR indicates the frontward direction of the vehicle, an arrow LH indicates the leftward direction of the vehicle, and an arrow RH indicates the rightward direction of the vehicle respectively.
As shown in Fig. 1, a pair of left and right front forks 3 which pivotally support a front wheel 2 of a motorcycle (a vehicle) 1 is pivotally supported on a head pipe 6 which is mounted on a front end portion of a vehicle body frame 5 by way of a steering stem 4 in a steerable manner. Further, a swing arm 8 which pivotally supports a rear wheel 7 has a front

end portion thereof pivotally supported on a pivot shaft 9 which is provided to an approximately center of the vehicle body frame 5 in a rockable manner. The vehicle body frame 5 is mainly constituted of a main frame 11 which rearwardly extends from an upper portion of the head pipe 6 and then is downwardly curved thus forming a so-called diamond-type frame. That is, in the vehicle body frame 5, pivot plates 12 which are mounted on both sides of a lower end portion of the main frame 11 and a lower end portion of a down tube 13 which extends obliquely in the rearward and downward direction from a lower portion of the head pipe 6 are respectively connected to the front and the rear portions of a crank case 51 of an engine (an internal combustion engine) 50 which is mounted on the center of a vehicle body, and the engine 50 is suspended from the vehicle body frame 5 by way of the down tube 13 and the pivot plates 12. [0011]
A front end portion of a sheet frame 16 which rearwardly extends is connected to a rear side of an upper-portion of the main frame 11, while an upper end portion of a sub frame 17 which extends obliquely in the rearward and upward direction from the vicinity of the pivot shaft 9 is connected to an intermediate portion of the sheet frame 16. A rear cushion 18 is arranged in a frontwardly inclined posture behind the main frame 11, while the rear cushion 18 has an upper end portion

thereof connected to the main frame 11 and a lower portion thereof connected to the swing arm 8 respectively.
A rear sprocket wheel 19 is mounted on a left side portion of the rear wheel 7, and a drive chain 22 is extended between and is wrapped around the rear sprocket wheel 19 and a drive sprocket wheel 21 which is arranged on the left side of the rear portion of the engine 50 and hence, a driving force of the engine 50 can be transmitted to the rear wheel 7.
A fuel tank 24 is arranged above the engine 50 and a seat 25 is arranged behind the fuel tank 24.
A bar handle 32 is mounted on an upper portion of a steering stem 4, and a front fender 33 is mounted on an intermediate portion of the front forks 3. Further, on the steering stem 4, a head lamp 34 and a front cowl 37 are mounted by way of supporting stays not shown in the drawings.
Side covers 38 are mounted on both sides of a center portion of the vehicle body frame 5, while a rear cowl 39 is mounted on a rear portion of the vehicle body frame 5. In the inside of the rear cowl 39, a rear fender 31 is arranged to cover the rear wheel 7 from above with a predetermined space therebetween. [0012]
As shown in Fig.2, Fig. 4 and Fig. 5, the engine 50 includes, as main component thereof, a crank case 51, a cylinder block 52, a cylinder head 53, a cylinder head cover 54, a piston

55, a crank shaft 56 and a connecting rod 57. The engine 50 has the cylinder block 52 thereof which is mounted on the crank case 51 arranged in a slightly frontwardly inclined posture toward a front side of the vehicle.
As shown in Fig. 5, the piston 55 which is slidably housed in the cylinder block 52 in the axial direction of the cylinder block 52 and the crankshaft 56 which is rotatably arranged in the inside of the crank case 51 are connected by way of the connecting rod 57 thus converting a reciprocating motion of the piston 55 into a rotational motion of the crank shaft 56. [0013]
The crankshaft 56 is connected with a main shaft 60 of a shift drum transmission 59 by way of a primary drive gear 27, a primary driven gear 28 and a clutch mechanism 58 in a connectable and disconnectable manner, while the main shaft
60 is connected to a counter shaft 62 by way of shift gears
61 thus enabling the transmission of the rotation of the crank
shaft 56 to the counter shaft 62. Here, in Fig. 5, one set
of meshing shift gears 61 is shown as a representative example
of shift gears, and other sets of shift gears are omitted from
the drawings. The above-mentioned drive sprocket wheel 21 is
mounted on an end portion of the counter shaft 62, and as
described previously, the rotation of the drive sprocket wheel
21 is transmitted to the rear sprocket wheel 19 using the drive
chain 22.

[0014]
The cylinder head 53 is mounted on an upper portion of the cylinder block 52 thus forming a combustion chamber 63 which is defined by the cylinder head 53 and the piston 55. The cylinder head 53 has an ignition-plug mounting portion 68 arranged at an approximately right center portion thereof, an ignition plug 64 is threadedly mounted on the ignition-plug mounting portion 68 in a state that the ignition plug 64 extends toward the combustion chamber 63 obliquely from above the ignition-plug mounting portion 68 whereby an electrode formed on an distal end portion of the ignition plug 64 projects into the inside of the combustion chamber 63.
As shown in Fig. 2 and Fig. 3, the cylinder head 53 is provided with an exhaust port 65 on a vehicle-body front side thereof, and an intake port 66 on a vehicle-body rear side thereof. These ports are respectively communicated to the combustion chamber 63 and the respective openings of these ports which face the combustion chamber 63 can be opened and closed by an exhaust valve and an intake valve (neither one of these valves are shown in the drawings). Here, as shown in Fig. 1, the exhaust port 65 is connected to a silencer 44 which is arranged on a right side of the rear portion of the vehicle body by way of an exhaust pipe 43, while the intake port 66 is connected to an air cleaner 46 by way of a carburetor 45.

[0015]
The exhaust valve and the intake valve are biased in a valve closing direction by valve springs (not shown in the drawings), and the valves can be opened at a predetermined timings against the valve springs by a valve operating mechanism 70 (see Fig. 5) which is arranged above the cylinder head 53. Although the detailed explanation of the valve operating mechanism 70 is omitted since the valve operating mechanism 70 is a well-known art, the valve operating mechanism
70 includes cams and cam shafts 71, rocker arms (not shown in
drawings), tappets (not shown in drawings) and the like.
A holder 67 is fixed to an upper center portion of the cylinder head 53, and bearings 72, 72 which rotatably support the cam shafts 71 of the valve operating mechanism 70 are sandwiched between the cylinder head 53 and the holder 67. A cam chain 81 is extended between and is wrapped around a cam sprocket wheel 73 which is fixed to one end of the cam shaft
71 and a cam drive sprocket wheel 80 which is fixed to the crank
shaft 56 so as to rotatably drive the cam shaft 71 in an
interlocking manner with the crank shaft 56.
[0016]
As shown in Fig. 4, the cylinder head 53 and the cylinder block 52 are fastened to the crank case 51 using bolts 41 which penetrate the cylinder head 53 and the cylinder block 52 are threaded into the crank case 51, while the holder 67 is fixed

to the cylinder head 53 by fastening nuts 43 which penetrate the holder 67 to stud bolts 42 which penetrate the cylinder head 53 and the cylinder block 52 and are threaded into the crank case 51. [0017]
Cooling fins 82 which extend in the circumferential direction are provided to an outer periphery of the cylinder block 52 in a projecting manner. Cooling fins 83 which extend in the circumferential direction are also mounted on an outer periphery of the cylinder head 53 in a projecting manner in a state that the cooling fins 83 do not interfere with the exhaust port 65, the intake port 66 and the ignition plug mounting portion 68.
A gasket surface 84 is formed on an outer edge portion of an upper surface of the cylinder head 53, and the cylinder head cover 54 is mounted on the gasket surface 84 by way of a rubber-made gasket 90.
[0018]
Fig. 6 is a bottom view as viewed from a bottom of the cylinder head cover 54. The cylinder head cover 54 has a substantially rectangular shape as viewed in a plan view. A valve train chamber 85 which houses the above-mentioned valve operating mechanism 70 is formed in the inside of a center portion of the cylinder head cover 54. As shown in Fig. 2, Fig. 4 and Fig. 5, the valve train chamber 85 is surrounded

by a top plate portion 86 of the cylinder head cover 54 and a first circular longitudinal wall 87 which downwardly extends from the top plate portion 86 • Further, the cylinder head cover 54 includes second longitudinal walls 88 outside the first longitudinal wall 87, and an upper end of the second longitudinal walls 88 are contiguously formed with an outer peripheral edge of the top plate portion 86 . That is, the outer peripheral portion of the cylinder head cover 54 has the duplicate structure which is constituted of double longitudinal walls 87, 88.
Further, a bottom surface of the first longitudinal wall 87 is mounted on the gasket surface 84 of the cylinder head 53 with a gasket 90 sandwiched therebetween. A gasket-fitting groove 89 is formed in the bottom surface of the first longitudinal wall 87, and a projection which is formed on an upper portion of the gasket 90 is fitted into the gasket-fitting groove 89. As shown in Fig. 2, Fig, 4 and Fig. 5, bottom surfaces of the second longitudinal walls 88 are positioned slightly higher than the bottom surface of the first longitudinal wall 87. [0019]
The cylinder head cover 54 has a recessed portion 91 which is indented toward the inside thereof at a right side center portion thereof. As shown in Fig. 6, the recessed portion 91 is positioned on the upper extension of the ignition plug 64.

As shown in Fig. 5, at the recessed portion 91, all of the top plate portion 86, the first longitudinal wall 87 and the second longitudinal walls 88 are indented toward the inside of these portions, and the second longitudinal walls 88 are closed at the recessed portion 91, and a closing wall 92F of the vehicle-body front side and a closing wall 92R of the vehicle-body rear side are contiguously formed with the first longitudinal wall 87. The closing walls 92F, 92R extend downwardly and obliquely toward the ignition plug 64. Further, the second longitudinal walls 88 are closed at a vehicle-body rear side and a vehicle-body front side in an interrupted manner,
and closing walls 93, 93 ••• are contiguously formed with the
first longitudinal wall 87.
[0020]
A cavity 98 is formed between the first longitudinal wall 87 and the second longitudinal walls 88. The cavity 98 has an upper side thereof closed by the top plate portion 86 and a lower side thereof opened so as to allow air to flow into and to flow out from the cavity freely. Further, the first longitudinal wall 87 and the second longitudinal walls 88 are connected with each other by a pair of ribs 94 at four corners and at a center of the left side thereof as viewed in a plan view, respectively. By providing the ribs 94 in this manner, it is possible to, while ensuring predetermined strength of the cylinder head cover 54, reduce a thickness of the second

longitudinal walls 88 thus realizing the reduction of weight of the cylinder head cover 54 and eventually the reduction of weight of the engine 50.
The cylinder head cover 54 is, as shown in Fig. 2, fastened to the cylinder head 53 by inserting bolts 96 into mounting holes 95 formed on the top plate portion 86 and threadedly engaging the bolts 96 into holders 67 . Here, the gasket surface 84 of the cylinder head 53 and the bottom surface of the first longitudinal wall 87 of the cylinder head cover 54 are brought into pressure contact with the gasket 90 thus providing the sealing between the cylinder head 53 and the cylinder head cover 54. [0021]
In the engine 50 of the motorcycle 1 having the above-mentioned constitution, since the outer peripheral portion of the cylinder head cover 54 adopts the duplicate structure which is constituted of the first longitudinal wall 87 and the second longitudinal walls 88, it is possible to enhance a soundproof effect. Further, a heat radiation area of the cylinder head cover 54 is increased compared to a heat radiation area of a cylinder head cover having no second longitudinal walls 88 thus enhancing an engine cooling effect. [0022]
Further, during traveling, a traveling wind is allowed to flow into the cavity 98 which is formed between the first

longitudinal wall 87 and the second longitudinal walls 88 of the cylinder head cover 54. Particularly, as shown in Fig. 3, when the traveling wind which flows in the cavity 98 of the right front side of the vehicle body impinges on the closing wall 92F on the vehicle-body front side at the recessed portion 91, the traveling wind changes the direction of flow thereof in the downward and oblique direction and flows toward the ignition plug 64. That is, the closing wall 92F functions as a guide portion which guides a traveling wind to flow in the direction toward the ignition plug 64. Accordingly, it is possible to effectively cool the combustion chamber 63 around the ignition-plug mounting portion 68 without adopting the complicated cylinder-head cover structure. Further, the merchantability of appearance of the cylinder head cover can be improved. [0023]
•Particularly, in~this motorcycle 1, the cylinder block 52 of the engine 1 is inclined forwardly and hence, the traveling wind which impinges on the upper most cooling fin 83 of the cylinder head 53 and changes the direction of flow thereof upwardly can easily enter the cavity 98 and hence, it is possible to effectively cool the periphery of the ignition-plug mounting portion 68. Accordingly, it is possible to efficiently cool the engine 50 of the motorcycle 1.

[Brief Explanation of Drawings]
[0024]
[Fig. 1]
A side view of a motorcycle according to the present invention. [Fig. 2]
A right side view with a part broken away of an internal combustion engine according to the present invention. [Fig. 3]
A right side view for explaining the flow of a traveling wind in the above-mentioned internal combustion engine. [Fig. 4]
A cross-sectional view of the above-mentioned internal combustion engine. [Fig. 5]
A cross-sectional view showing a transmission part of the above-mentioned internal combustion engine in a developed manner. [Fig. 6]
A bottom view of a cylinder head cover of the above-mentioned internal combustion engine. [Description of Reference Numerals and Signs] [0025]
1: motorcycle 50: engine (internal combustion engine)

52: cylinder block
53: cylinder head
54: cylinder head cover
63: combustion chamber
64: ignition plug
87: first longitudinal wall
88: second longitudinal wall
91: recessed portion
92F: closing wall (guide portion)
94: rib

[Designation of Document] Claims [Claim 1]
An air-cooled internal combustion engine which closes an upper end of a cylinder block with a cylinder head thus forming a combustion chamber inside the cylinder block and that a cylinder head cover is mounted on the cylinder head, wherein
an outer peripheral portion of the cylinder head cover has the duplicate structure which is constituted of double longitudinal walls. [Claim 2]
The internal combustion engine according to claim 1, wherein the double longitudinal walls are connected with each other by ribs, [Claim 3]
The internal combustion engine according to claim 1, wherein a space defined between the double longitudinal walls has a lower side thereof opened and an upper side thereof closed. [Claim 4]
The internal combustion engine according to claim 3, wherein the cylinder head cover includes a recessed portion on an upper extension of an ignition plug which is mounted on the cylinder head and also includes a guide portion which guides a traveling wind which flows in a space defined between the double longitudinal walls in a state that the traveling wind

is directed toward the ignition plug. [Claim 5]
A motorcycle which mounts the internal combustion engine described in claim 4, wherein the cylinder block of the internal combustion engine is arranged to be inclined forwardly toward a front side of a vehicle body.
Dated this 23 day of November 2006


Documents:

2173-CHE-2006 CORRESPONDENCE OTHERS.pdf

2173-CHE-2006 CORRESPONDENCE PO.pdf

2173-CHE-2006 DESCRIPTION (COMPLETE) 13-08-2009.pdf

2173-CHE-2006 DRAWING 13-08-2009.pdf

2173-CHE-2006 EXAMINATION REPORT REPLY RECIEVED 13-08-2009.pdf

2173-che-2006 form-1 13-08-2009.pdf

2173-che-2006 form-3 13-08-2009.pdf

2173-che-2006 form-5 13-08-2009.pdf

2173-CHE-2006 PETITION 13-08-2009.pdf

2173-che-2006-abstract.pdf

2173-che-2006-abstractimage.jpg

2173-che-2006-claims.pdf

2173-che-2006-correspondnece-others.pdf

2173-che-2006-description(complete).pdf

2173-che-2006-drawings.pdf

2173-che-2006-form 1.pdf

2173-che-2006-form 18.pdf

2173-che-2006-form 26.pdf

2173-che-2006-form 3.pdf

2173-che-2006-form 5.pdf

2173-che-2006-priority.pdf


Patent Number 240447
Indian Patent Application Number 2173/CHE/2006
PG Journal Number 21/2010
Publication Date 21-May-2010
Grant Date 12-May-2010
Date of Filing 23-Nov-2006
Name of Patentee HONDA MOTOR CO., LTD
Applicant Address 1-1 MINAMI-AOYAMA 2-CHOME MINATOKU TOKYO 107-8556 JAPAN
Inventors:
# Inventor's Name Inventor's Address
1 ANDO JUNJI C/O HONDA R 7D CO LTD 4-1 CHUO 1-CHOME WAKO-SHI SAITAMA 35-0193 JAPAN
PCT International Classification Number F02F1/34
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2005-345237 2005-11-30 Japan