JPS6315580Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an engine intake duct mounting structure suitable for motorcycles and the like with little space.

(Prior art) In conventional motorcycles, for example, as shown in Fig. 1, the cylindrical duct body 1 is made of a flexible rubber-like elastic material such as vinyl chloride rubber and is formed into a linear shape with a smooth inner surface. Then, the boss tube 2 on the front engine side is fitted into the intake tube 4 of the carburetor 3 and fastened with a band 5 or the like, and two outward flanges 6 are attached to the outer peripheral surface of the rear end.
The annular groove 7 between the flanges 6 and 6 is elastically fitted into the duct connecting hole 9 of the air cleaner 8. The air cleaner 8 is integrally molded with resin, for example, and is fixed to the vehicle body. Also, the discharge tube 1 of the vaporizer 3
1 is connected to an intake cylinder 14 of an engine 13 via a holder 12. 15 is a band. At the time of assembly, the carburetor 3 was fixed in advance to the engine 13 side, and the duct body 1 was fitted in the air cleaner 8 in advance, and the air cleaner 8 was temporarily fixed so that it could be moved slightly back and forth with respect to the vehicle body. In this state, the boss tube 2 at the front end of the duct is fitted into the intake tube 4 of the carburetor 3 from behind, and after the band 5 is attached, the air cleaner 8 is finally fastened to the vehicle body.

However, the larger the volume of the air cleaner 8, the better from the viewpoint of filtration performance and intake noise silencing performance. Therefore, the front wall 8a of the air cleaner should be largely extended toward the engine 13, and the backlash between the air cleaner 8 and the vehicle body in the longitudinal direction should be reduced. It is desirable by design to do so.
However, if the duct body 1 is straight as shown in Figure 1, it is difficult to shorten the total length of the duct body 1 to less than a certain amount due to the work involved in bending the duct body 1 and connecting it to the carburetor 3. Therefore, the volume of the air cleaner is also limited. Also air cleaner 8
Since the annular groove 7 of the duct main body 1 is only elastically fitted into the duct connection hole 9, the sealing performance tends to be insufficient. As a countermeasure to this problem, if the annular groove 7 is made deeper, it becomes difficult to attach and detach the duct body 1, and the cost also increases.

(Purpose of the invention) The present invention improves the structure of the cylindrical duct body so that even if the front wall of the air cleaner extends significantly toward the engine side, there will be no problem in attaching and detaching the duct body to the carburetor 3. The purpose of this invention is to improve the sealing performance between the duct connection hole of the air cleaner and the duct body.

(Structure of the invention) The present invention has a cylindrical duct body made of a rubber-like elastic material whose front end on the downstream side is connected to a carburetor and whose rear end has a tapered part whose inner surface widens as it goes rearward. It extends forward to the middle part of the cylindrical duct body and has an annular shape with respect to the outer peripheral surface of the cylindrical duct body.
A boss tube with a space between the two is integrally formed, and an annular groove provided on the outer circumferential surface of the front end of the boss tube is fitted into a duct connecting hole provided on the front wall of the air cleaner, and an expansion seal is installed on the inner circumferential surface of the boss tube behind the annular groove. This is an engine intake duct mounting structure characterized by a pressure-welded spring.

(Example) The cylindrical duct main body 20 shown in FIG. 2 is made of a rubber-like elastic body similar to the conventional one, and the boss cylinder 21 on the side of the carburetor 3 has an annular projection 22 on the inner peripheral surface to improve sealing performance. It has an annular groove 23 on its outer periphery into which a spring band is fitted. The duct main body 20 has a tapered part 24 in the rear half that smoothly expands as the inner surface goes upstream (inwardly rearward of the air cleaner 8), and a boss cylinder 25 is folded back from the rear end edge of the tapered part 24. An annular gap 26 is formed between the boss tube 25 and the duct body 20. A pair of low outward flanges 2 are provided on the outer peripheral surface of the front end of the boss cylinder 25.
7, 27 are provided, and the duct connecting hole 2 of the air cleaner 8 is provided in the annular groove 28 between both flanges 27, 27.
9 is inserted. A C-clip 30 made of a leaf spring is pressed against the inner circumference of the boss tube 25 in a reduced diameter state, so that the boss tube 25 is forcibly pressed against the inner surface of the duct connection hole 29 of the air cleaner 8. There is.

At the time of assembly, the carburetor 3 is previously attached to the engine as before. The duct body 20 is also the air cleaner 8
It is installed in advance. When the boss cylinder 21 at the front end of the duct is fitted into the intake cylinder 4 of the carburetor 3 with the air cleaner 8 with the duct body temporarily attached to the vehicle body, the folded part consisting of the tapered part 24 and the boss cylinder 25 is attached to the duct body 20. As a result, the flexibility of the duct body 20 in the axial direction is increased, and therefore, the boss tube 21 at the front end of the duct can be used to bend the duct body 20 while also utilizing the slight backlash of the air cleaner 8 in the front and back direction. and then move the rear boss tube 21 backward in the direction of arrow A.
into the intake cylinder 4 of the carburetor 3, and attach a spring band to the groove 23. After that, the air cleaner 8 is finally fastened to the vehicle body. While the engine is running,
The air purified within the air cleaner 8 is guided by the smooth inner surface within the duct body 20 and flows into the carburetor 3.

(Effect of the invention) In the present invention, the cylindrical duct main body 20 is made of a rubber-like elastic material, and the downstream front end is connected to the carburetor 3, and the rear end has a tapered part 24 that widens as the inner surface goes rearward. A boss cylinder 25 is integrally formed, extending forward from the rear end to the middle part of the cylindrical duct body 20 and separated from the outer peripheral surface of the cylindrical duct body by an annular gap 26. The provided annular groove 28 is fitted into the duct connection hole 29 provided in the air cleaner front wall 8a, and an expansion sealing spring (for example, C clip 30) is pressed against the inner peripheral surface of the boss cylinder behind the annular groove. This allows you to obtain special effects such as. That is, the flexibility of the duct body 20 in the axial direction is increased, and even though the duct body 20 only slightly protrudes forward from the front wall 8a of the air cleaner 8, the front end boss of the duct body 20 when connected to the carburetor 3. Move the tube 21 backward (arrow A
The duct can be fitted onto the outer circumferential surface of the intake pipe 4 of the carburetor 3 after it is deflected significantly in the direction (direction) to avoid the intake pipe 4 of the carburetor 3, and the work of attaching the duct to the carburetor 3 can be carried out smoothly. This allows the air cleaner front wall 8a to extend significantly toward the carburetor 3 side, increasing the volume of the air cleaner 8, and improving filtration performance, intake air silencing performance, etc. Furthermore, since an expansion sealing spring such as a C clip 30 is attached to the inner circumferential surface of the boss cylinder 25 from within the gap 26, the sealing performance against the duct connection hole 29 can be improved even if the annular groove 28 is formed shallowly. This also simplifies the installation work to the duct connection hole 29. Since there is no need to provide a boss tube that fits into the boss tube 25 on the air cleaner front wall 8a, there is no need to make the boss tube 25 long, and the connection between the duct connecting hole 29 bored in the front wall 8a and the bottom surface of the annular groove 28 is eliminated. The surface pressure increases, and sufficient sealing performance can be ensured with the relatively weak elasticity of the C-clip 30. Since the annular groove 28 is provided at the front end of the boss tube 25, the boss tube 2
5 can be maintained at a high level of flexibility in the radial direction, which is also effective in increasing the axial flexibility of the duct body 20. Furthermore, according to the present invention, the rear half of the duct (tapered part 24) that protrudes into the air cleaner 8 in order to fold back the boss tube 25 on the outer peripheral side of the duct body 20 plays the role of a guide member that reduces air outflow resistance. Performance will also improve in terms of performance. Furthermore, since the boss tube 25 is integrally connected to the rear end edge of the tapered portion 24, the rigidity is increased, and there is no possibility that vibration noise will be generated in the tapered portion 24 when air flows out from the air cleaner 8.

[Brief explanation of drawings]

FIG. 1 is a partial vertical cross-sectional side view showing a conventional structure, and FIG. 2 is a partial vertical cross-sectional view showing a duct mounting structure according to the present invention. 3... Carburetor, 8... Air cleaner, 20...
Cylindrical duct body, 25...Boss tube, 26...〓
Between, 29...Duct connection hole.

Claims (1)

[Scope of utility model registration request] A cylindrical duct body made of a rubber-like elastic body whose front end on the downstream side is connected to the carburetor and whose rear end has a tapered part whose inner surface widens as it goes rearward, from the rear end of the tapered part to the middle part of the cylindrical duct body. A boss tube extending forward and separated from the outer peripheral surface of the cylindrical duct body by an annular gap is integrally formed, and the annular groove provided on the outer peripheral surface of the front end of the boss tube is connected to the duct connecting hole provided in the front wall of the air cleaner. An engine intake duct mounting structure characterized in that an expansion sealing spring is fitted and press-contacted to the inner circumferential surface of the boss cylinder behind the annular groove.