Title of Invention

AN INTAKE SYSTEM FOR A COMPACT VEHICLE

Abstract In a compact vehicle having a backbone type body frame having a main frame extending rearward from a head pipe so that the axis of the main frame lies on a plane containing a body center line and the main frame has a rear portion extending substantially vertically, an engine body mounted on the body frame, and an induction system connected to a cylinder head of the engine body, the induction system including a carburetor located on one lateral side of the main frame, the carburetor having an inlet axis inclined closer to the body center line toward the engine body, the induction resistance between the carburetor and the cylinder head without complication of the structure of the body frame is reduced, thereby improving the engine performance and reducing the fuel consumption. The side surface of the main frame 13 opposed to the carburetor 39 is formed with a recess 44 allowing the carburetor 39 to be positioned closer to the body center line C.
Full Text

[Name of Document] Specification
[Title of the Invention]
Carburetor Layout Structure in Compact Vehicle
[Technical Field]
[0001]
The present invention relates to a compact vehicle having a backbone type body frame having a head pipe for steerably supporting a front fork and a main frame extending rearward from said head pipe so that the axis of said main frame lies on a plane containing a body center line and said main frame has a rear portion extending substantially vertically, an engine body mounted on said body frame and located on the front side of said rear portion of said main frame, and an induction system connected to a cylinder head of said engine body, said induction system including a carburetor located on one lateral side of said main frame, said carburetor having an inlet passage having an inlet axis inclined closer to said body center line toward said engine body and a throttle valve for controlling the amount of air flowing in said inlet passage, and more particularly to an improvement in a carburetor layout structure.
[Background Art]
[0002]

Conventionally known in Patent Document 1, for example, is a motorcycle having a backbone type body frame, wherein a carburetor constituting a part of an induction system is located on one lateral side of a main frame constituting a part of the body frame. [Patent Document 1]
Japanese Utility Model Laid-Open No. 2-118157 [Disclosure of the Invention] [Problem to be Solved by the Invention]
[0003]
The carburetor is located on one lateral side of the main frame so as to avoid the interference with the main frame. The axis of the main frame lies on a plane containing a body center line which is laterally central line of the vehicle, and the inlet axis of an inlet passage in the carburetor is therefore inclined closer to the body center line toward an engine body. In the motorcycle disclosed in Patent Document 1, the main frame has a rear portion laterally divided into a right portion and a left portion, and the inlet axis extends between the body frame and a rear cushion. Accordingly, the angle of inclination of the inlet axis in the carburetor with respect to the body center line is relatively large, so that an inlet passage between the carburetor and a

cylinder head of the engine body must be largely bent. As a result, the structure of the body frame is complicated to cause a relatively large induction resistance.
[0004]
It is accordingly an object of the present invention to provide a carburetor layout structure in a compact vehicle which can reduce the induction resistance between the carburetor and the cylinder head without complication of the structure of the body frame, thereby improving the engine performance and reducing the fuel consumption.
[Means for Solving the Problem]
[0005]
In accordance with the invention as defined in claim 1, there is provided in a compact vehicle having a backbone type body frame having a head pipe for steerably supporting a front fork and a main frame extending rearward from the head pipe so that the axis of the main frame lies on a plane containing a body center line and the main frame has a rear portion extending substantially vertically, an engine body mounted on the body frame and located on the front side of the rear portion of the main frame, and an induction system connected to a cylinder head of the engine body, the induction system including a

carburetor located on one lateral side of the main frame, the carburetor having an inlet passage having an inlet axis inclined closer to the body center line toward the engine body and a throttle valve for controlling the amount of air flowing in the inlet passage; a carburetor layout structure characterized in that the side surface of the main frame opposed to the carburetor is formed with a recess allowing the carburetor to be positioned closer to the body center line.
[0006]
In accordance with the invention as defined in claim 2 including the configuration of the invention as defined in claim 1, a throttle drum and a throttle sensor are coaxially mounted on opposite end portions of a shaft for operating the throttle valve, and any one of the throttle drum and the throttle sensor is located near the main frame.
[0007]
In accordance with the invention as defined in claim 3 including the configuration of the invention as defined in claim 2, the throttle sensor is located near the main frame.
[Effect of the Invention]
[0008]

According to the invention as defined in claim 1, the carburetor can be positioned closer to the body center line. That is, the angle of inclination of the inlet axis of the carburetor with respect to the body center line can be set relatively small without complication of the structure of the body frame, so that it is unnecessary to largely bend the inlet passage between the carburetor and the cylinder head. As a result, the induction resistance between the carburetor and the cylinder head can be suppressed to thereby improve the engine performance and reduce the fuel consumption.
[0009]
According to the invention as defined in claim 2, the configuration of the carburetor can be simplified by coaxially mounting the throttle drum and the throttle sensor on the opposite end portions of the shaft for the throttle valve. Furthermore, the carburetor can be positioned closer to the body center line.
[0010]
According to the invention as defined in claim 3, the throttle sensor as electrical equipment can be protected by the main frame.
[Best Mode for Carrying out the Invention]
[0011]

A preferred embodiment of the present invention will now be described with reference to the attached drawings.
[0012]
FIGS. 1 to 5 show a preferred embodiment of the present invention, wherein FIG. 1 is a side view of a motorcycle, FIG. 2 is an enlarged view of an essential part of FIG. 1, FIG. 3 is a cross section taken along the line 3-3 in FIG. 2, FIG. 4 is a view taken in the direction shown by an arrow 4 in FIG. 3, and FIG. 5 is a vertical sectional view of a carburetor.
[0013]
Referring first to FIG. 1, the motorcycle as a compact vehicle has a body frame F. The body frame F is of a backbone type including a head pipe 12 for steerably supporting a front fork 11 for rotatably supporting a front wheel WF, a single main frame 13 having a gently inclined portion 13a extending rearward from the head pipe 12 so as to be inclined gently downward and a steeply inclined portion 13b extending rearward from the rear end of the gently inclined portion 13a so as to be inclined steeply downward, a pivot plate 14 mounted on a rear end portion of the steeply inclined portion 13b of the main frame 13, a pair of right and left seat rails 15

extending rearward from the main frame 13 so that the front ends of the seat rails 15 are connected to a joining portion between the gently inclined portion 13a and the steeply inclined portion 13b, a single down frame 16 extending rearward from the head pipe 12 so as to be inclined downward so that the front end of the down frame 16 is connected to a lower portion of the head pipe 12 below the front end of the main frame 13, a subpipe 17 connected between the gently inclined portion 13a of the main frame 13 and the down frame 16, and a pair of right and left reinforcing frames 18 connected between the pivot plate 14 and the right and left seat rails 15, respectively.
[0014]
Referring also to FIG. 2, there is shown a single-cylinder engine having an engine body 21. The engine body 21 is composed generally of a crankcase 23 for supporting a crankshaft 2 2 whose axis extends in the lateral direction of the motorcycle, a cylinder body 24 joined to the crankcase 23, a cylinder head 25 joined to the cylinder body 24, and a head cover 26 joined to the cylinder head 25. The engine body 21 is located in a space surrounded by the main frame 13, the pivot plate 14, and the down frame 16 of the body frame F. The crankcase

23 is supported at upper and lower two positions of its front portion to a bracket 27 mounted to a lower end portion of the down frame 16. The crankcase 23 is further supported at upper and lower two positions of its rear portion to the pivot plate 14.
[0015]
A transmission (not shown) for transmitting rotational power output from the crankshaft 22 with its rotational speed varied is accommodated in the crankcase 23. The transmission has an output shaft 28 whose one end portion projects outward from the crankcase 23 at a position behind the crankshaft 22. As shown in FIG. 1, an endless chain 31 is wrapped between a drive sprocket 29 fixed to the projecting end portion of the output shaft 28 and a driven sprocket 30 fixed to the axle of a rear wheel WR.
[0016]
The axle of the rear wheel WR is rotatably supported to a rear end portion of a swing arm 32. The swing arm 32 is supported at its front end portion to the pivot plate 14 in such a manner as to be pivotable about the axis of a connecting shaft 33 for connecting the reinforcing frames 18 to the pivot plate 14. Further, a pair of right and left rear cushion units 34 are

connected between the rear ends of the reinforcing frames 18 joined to the seat rails 15 and a rear end portion of the swing arm 32.
[0017]
An exhaust pipe 35 is connected at its upstream end to a front side wall of the cylinder head 25. The exhaust pipe 35 extends downward on the front side of the engine body 21 and further extends rearward on the lower side of the crankcase 23. The downstream end of the exhaust pipe 35 is connected to an exhaust muffler 36 located on the right side of the rear wheel WR.
[0018]
Referring also to FIG. 3, an induction system 37 is connected to a rear side wall of the cylinder head 25 of the engine body 21 located on the front side of the rear portion of the main frame 13, i.e., the steeply inclined portion 13b. The induction system 37 includes an inlet pipe 3 8 connected at its downstream end to the rear side wall of the cylinder head 25, a carburetor 39 located on the rear side of the inlet pipe 38, and an air cleaner 40 located on the rear side of the carburetor 3 9 so that most of the air cleaner 40 is located behind the steeply inclined portion 13b of the main frame 13. The upstream end of the inlet pipe 3 8 is connected through a

connection pipe 41 such as a hose to the downstream end of the carburetor 39. The upstream end of the carburetor 3 9 is connected through a connection pipe 42 such as a hose to an outlet pipe 4 0a included in the air cleaner 4 0.
[0019]
The main frame 13 of the body frame F is formed by bending a metal pipe so that the axis of the main frame 13 lies on a plane containing a body center line C which is a laterally central line of the vehicle. The carburetor 3 9 is located on the right side of an upper portion of the steeply inclined portion 13b of the main frame 13.
[0020]
Referring also to FIG. 4, a side surface of the upper portion of the steeply inclined portion 13b of the main frame 13 opposed to the carburetor 3 9 is formed with a recess 44 allowing the carburetor 39 to be positioned closer to the body center line C. The recess 44 is formed by drawing a part of the main frame 13.
[0021]
Referring next to FIG. 5, the carburetor 3 9 has a carburetor body 45. The carburetor body 45 is formed as an integral body composed of a diaphragm chamber portion 45a as an upper portion and a flange 45b as a lower

portion. A float chamber member 47 is fastened to the lower surface of the flange 4 5b, thereby forming a float chamber 46 between the float chamber member 4 7 and the carburetor body 45. An inlet passage 48 extends through a central portion of the carburetor body 45. The carburetor body 45 is provided with a main nozzle 4 9 opening to the bottom surface of the inlet passage 48 and a plurality of slow nozzles 50 opening to the bottom surface of the inlet passage 48 at a position downstream of the main nozzle 4 9 along an air flowing direction shown by an arrow 64. The main nozzle 49 and the slow nozzles 50 respectively communicate with a main jet 51 and a slow jet 52 both opening to the underside of a fuel level in the float chamber 46.
[0022]
A piston valve 53 is provided immediately above the main nozzle 49. The piston valve 53 is slidably engaged with a guide hole 54 formed in the carburetor body 45. A diaphragm 55 is provided so that its inner bead portion is fixed to the upper end of the piston valve 53 and that the outer circumferential portion of the diaphragm 55 is sandwiched between the diaphragm chamber portion 45a of the carburetor body 45 and a cover member 56 fastened to the diaphragm chamber portion 45a. The space defined by

the diaphragm chamber portion 45a and the cover member 56 is partitioned by the diaphragm 55 into a venturi vacuum chamber 57 on the cover member 56 side and an atmospheric pressure chamber 58 on the diaphragm chamber portion 45a side. The venturi vacuum chamber 57 communicates with the inlet passage 4 8 through a plurality of vacuum introduction holes 59 opening to the lower end surface of the piston valve 53. The atmospheric pressure chamber 58 communicates with the atmosphere through an atmospheric pressure introduction hole 6 0 opening to the upstream end surface of the carburetor body 45.
[0023]
The piston valve 53 is normally biased in the downward direction by a return spring 61 accommodated in the venturi vacuum chamber 57. At the lowermost position of the piston valve 53, a primary venturi 62 is formed in the inlet passage 48. A needle valve 63 is retained to the lower end of the piston valve 53 so as to be inserted into the main nozzle 49.
[0024]
A butterfly type throttle valve 65 for controlling the amount of air flowing in the inlet passage 48 is located in the vicinity of the slow nozzles 50 downstream of the piston valve 53. A shaft 66 for operating the

throttle valve 65 is pivotably supported to the carburetor body 45. The shaft 66 projects at its opposite end portions from the carburetor body 45, and a throttle drum 67 and a throttle sensor 68 are coaxially mounted on the projecting end portions of the shaft 66.
[0025]
Referring again to FIG. 3, the carburetor 39 is located on the right side of the upper portion of the steeply inclined portion 13b of the main frame 13 in such a manner that the inlet axis IC of the inlet passage 48 is inclined closer to the body center line C toward the engine body 21. Further, any one of the throttle drum 67 and the throttle sensor 68 coaxially mounted on the opposite end portions of the shaft 66 for the throttle valve 65 is located near the main frame 13. In this preferred embodiment, the throttle sensor 68 is partially received in the recess 44 of the main frame 13.
[0026]
The operation of this preferred embodiment will now be described. As mentioned above, the engine body 21 is mounted on the backbone type body frame F having the main frame 13 extending rearward from the head pipe 12 so that the axis of the main frame 13 lies on the plane containing the body center line C. The engine body 21 is

located on the front side of the steeply inclined portion 13b of the main frame 13 as the rear portion thereof. Further, the carburetor 39 having the inlet passage 48 and the throttle valve 65 is located on one lateral side of the main frame 13, wherein the inlet passage 48 has the inlet axis IC inclined closer to the body center line C toward the engine body 21, and the throttle valve 65 controls the amount of air flowing in the inlet passage 48. Further, the side surface of the main frame 13 opposed to the carburetor 39 is formed with the recess 44 allowing the carburetor 39 to be positioned closer to the body center line C.
[0027]
Accordingly, the carburetor 39 can be positioned closer to the body center line C so as to avoid the interference with the main frame 13. That is, the angle of inclination of the inlet axis IC of the carburetor 39 with respect to the body center line C can be set relatively small without complication of the structure of the body frame F, so that it is unnecessary to largely bend the inlet passage between the carburetor 3 9 and the cylinder head 25. As a result, the induction resistance between the carburetor 39 and the cylinder head 25 can be suppressed to thereby improve the engine performance and

reduce the fuel consumption.
[0028]
Further, any one of the throttle drum 67 and the throttle sensor 68 coaxially mounted on the opposite end portions of the shaft 66 for the throttle valve 65 is located near the main frame 13. Accordingly, the configuration of the carburetor 3 9 can be simplified by coaxially mounting the throttle drum 67 and the throttle sensor 68 on the opposite end portions of the shaft 66 for the throttle valve 65, and simultaneously the carburetor 3 9 can be positioned closer to the body center line C.
[0029]
Further, the throttle sensor 6 8 is located near the main frame 13 in this preferred embodiment, so that the throttle sensor 6 8 as electrical equipment can be protected by the main frame 13.
[0030]
While a specific preferred embodiment of the present invention has been described, it should be noted that the present invention is not limited to the above preferred embodiment, but various modifications may be made without departing from the scope of the present invention as defined in the claims.

[0031]
For example, while the present invention is applied to a motorcycle in the above preferred embodiment, the present invention is applicable also to any other compact vehicles such as a three-wheeled vehicle. [Brief Description of the Drawings]
[0032] [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 cross section taken along the line 3-3 in FIG. 2. [FIG. 4]
FIG. 4 is a view taken in the direction shown by an arrow 4 in FIG. 3. [FIG. 5]
FIG. 5 is a vertical sectional view of a carburetor. [Description of Reference Symbols] [0033]







[Name of Document] Claims [Claim 1]
In a compact vehicle having a backbone type body-frame (F) having a head pipe (12) for steerably supporting a front fork (11) and a main frame (13) extending rearward from said head pipe (12) so that the axis of said main frame (13) lies on a plane containing a body center line (C) and said main frame (13) has a rear portion extending substantially vertically, an engine body (21) mounted on said body frame (F) and located on the front side of said rear portion of said main frame (13), and an induction system (37) connected to a cylinder head (25) of said engine body (21), said induction system (3 7.) including a carburetor (39) located on one lateral side of said main frame (13), said carburetor (39) having an inlet passage (48) having an inlet axis (IC) inclined closer to said body center line (C) toward said engine body (21) and a throttle valve (65) for controlling the amount of air flowing in said inlet passage (48);
a carburetor layout structure characterized in that the side surface of said main frame (13) opposed to said carburetor (39) is formed with a recess (44) allowing the carburetor (39) to be positioned closer to said body

Documents:

1567-CHE-2006 CLAIMS GRANTED.pdf

1567-CHE-2006 CORRESPONDENCE OTHERS.pdf

1567-CHE-2006 CORRESPONDENCE PO.pdf

1567-CHE-2006 FORM 1.pdf

1567-che-2006-abstract.pdf

1567-che-2006-claims.pdf

1567-che-2006-correspondnece-others.pdf

1567-che-2006-description(complete).pdf

1567-che-2006-drawings.pdf

1567-che-2006-form 1.pdf

1567-che-2006-form 18.pdf

1567-che-2006-form 26.pdf

1567-che-2006-form 3.pdf

1567-che-2006-form 5.pdf


Patent Number 234545
Indian Patent Application Number 1567/CHE/2006
PG Journal Number 29/2009
Publication Date 17-Jul-2009
Grant Date 05-Jun-2009
Date of Filing 30-Aug-2006
Name of Patentee HONDA MOTOR CO., LTD
Applicant Address 1-1, Minami-Aoyama 2-chome, Minato-ku, Tokyo 107-8556,
Inventors:
# Inventor's Name Inventor's Address
1 SUZUKI, MAKOTO C/o Honda R&D Co., Ltd., 4-1, Chuo 1-chome, Wako-shi, Saitama 351-0193,
PCT International Classification Number B 62 K 11/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2005-252260 2005-08-31 Japan