JPS594819Y2 - motorcycle intake system - Google Patents

Description

[Detailed description of the invention] This invention is a motorcycle in which noise in the intake system is reduced by using the down tube, which is a part of the frame, and the expansion chamber in the press frame that supports it as an air intake passage to the air cleaner. This relates to an intake device.

The engine intake pipe and air cleaner case act as a kind of acoustic low-pass filter, and have the function of attenuating the sound pressure above a certain frequency among the sounds emitted from the engine intake system.

However, even with this, it is difficult to sufficiently attenuate the noise emitted from the intake system, so in order to further attenuate the noise from the intake system, a separate box may be provided integrally with the air cleaner.

In addition, in order to muffle lower frequency sounds with an air cleaner, the cross-sectional area of the air cleaner inlet pipe should be made as small as possible within the range that does not reduce engine performance, and the inlet pipe should be made longer, and the volume of the air cleaner case should be reduced. Bigger is better.

However, in motorcycles and the like, the installation space for the air cleaner is very small, so it is difficult to attach a box as a muffler to the air cleaner or to lengthen the air cleaner inlet pipe.

Further, some motorcycles have a frame made of a press frame formed by press-molding a plate body and a down tube with a lower rear end fixed to the front part of the press frame.

For motorcycles with such frames, it is conceivable to use the down tube as the air intake passage for the air cleaner in order to solve the above-mentioned problems, but depending on the direction in which the air inlet and air outlet are bored, There is a risk that the strength of the down tube will decrease.

In particular, since a downward force acts on the downtube, if the air inlet and air outlet are opened toward the bottom of the downtube, there is a risk that the strength of the downtube will decrease the most. be.

For this reason, it is desirable to form the air inlet and air outlet so as to avoid this direction.

The object of the present invention is to provide an intake device that meets this demand.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a motorcycle frame, and this frame 1 has a press frame 2 and a down chew 13.
Fru.

This press frame 2 is formed by press-molding a plate.

In the figure, 4 is a rear wheel supported by the press frame 2, 5 is a bundle supported by the front end upper part 3a of the down tube 3,
6 is a front fork supported on the upper front end of the down tube 3; 7 is a front wheel supported on the lower part of the front fork 6; 8 is an engine supported on the press frame 2; 9
is an air cleaner supported on the engine 8 side.

The down tube 3 is inclined from the upper front to the lower rear.

The lower rear end 3b (Fig. 2) of this down tube 3 is inserted into the press frame 2 through a hole 10 provided in the front part of the press frame 2, and the vicinity of its lower end is welded to the bottom plate 11 of the lower part of the press frame 2. Fixed.

Furthermore, the lower rear end 3b of the down tube 3 is closed by a lid 12 welded and fixed to the end surface.

Note that the hole 10 is provided at the front end of the pipe-shaped protrusion 2a at the front of the press frame 2, and the bottom plate 11 is welded and fixed to the lower part of the press frame 2.

Further, the down tube 3 is welded and fixed to the press frame 2 along the upper edge of the hole 10.

An air inlet 13 (FIG. 1) that opens laterally into the atmosphere is bored in the upper part of the down tube 3.

A partition plate 14 is welded and fixed within the protrusion 2a, and the lower end 3b of the down tube 3 passes through this partition plate 14.

An expansion chamber 15 is provided between the partition plate 14 and the inner surface of the protrusion 2a.
is formed.

The lower end 3b of the down tube 3 is provided with an air outlet 16.16 that opens laterally into the expansion chamber 15.

A pipe-shaped connection port 17 is provided in the lower part of the protrusion 2a.
are integrated.

A suction port (not shown) of the air cleaner 9 is connected to this connection port 17 via a flexible pipe 1B.

Next, the operation of the air cleaner intake device having such a configuration will be explained.

As the engine 8 operates, atmospheric air flows into the inlet 1
3 into the down tube 3.

Thereafter, the air sucked into the down tube 3 flows out from the outlet 16 into the expansion chamber 15 and diffuses, and then is sucked into the air cleaner 9 via the pipe 18.

Such actions of the down tube 3 and the expansion chamber 15 reduce noise during intake.

In the embodiment described above, the partition plate 14 is provided in the protrusion 2a, and the protrusion 2a, the down tube 3 and the partition plate 14 are
Although an expansion chamber is formed between the partition plate 1
4 is not necessary, and an expansion chamber may be formed between the press frame 2, the down tube 3, and the bottom plate 11.

Since the present invention is configured as explained above, the air suction passage of the air cleaner can be lengthened without attaching a box as a muffler to the air cleaner in the installation space of the air cleaner or lengthening the air cleaner itself. Since the expansion chamber can be provided as a noise reduction space, there is no need to provide any new parts especially for noise reduction.

Moreover, since the air inlet and air outlet holes drilled in the down tube are opened laterally, the air inlets and air outlets drilled into the down tube are opened laterally, so they are more open downward than if they were opened downward or in the middle direction between the downward and lateral directions. This has the advantage of increasing the strength of the downtube against the load on the other side.

[Brief explanation of drawings]

FIG. 1 is a side view of a motorcycle showing one embodiment of the present invention. FIG. 2 is an enlarged partial cross-sectional view of FIG. 1. 1... Frame, 2... Press frame, 3... Down tube,
3a... Upper front end, 3b... Lower rear end, 9... Air cleaner, 13... Inlet, 14... Partition plate, 1
5... Expansion chamber, 16... Outlet.

Claims (1)

[Scope of utility model registration request] In a motorcycle in which a front fork and a bundle are supported at the front of a press frame via a down tube that slopes from the upper part of the front to the lower part of the rear, a lateral air inlet opening to the atmosphere in the down tube is provided. The lower end of the down tube is inserted into the press frame and fixed to the press frame internally, and an expansion chamber is formed between the lower end of the down tube and the press frame. An air intake device for a motorcycle, characterized in that an air outlet opening laterally into an expansion chamber is provided at the lower end of the tube, and an air intake port of an air cleaner is connected to the expansion chamber.