JPS609517Y2 - motorcycle engine - Google Patents

Description

[Detailed explanation of the invention] The inventors conducted various experimental studies on noise reduction measures for motorcycle engines, and a series of studies revealed that among the noise emitted from motorcycle engine covers, the noise radiated from the chain cover is I confirmed that it was particularly large.

The chain cover covers the output transmission chain sprocket attached to the output shaft of a motorcycle engine, and because the rigidity of the cover is lower than other covers due to its structure, the resonance noise inherent to the cover is large. It was found that this was occurring.

In an experiment conducted by the inventors, they compared the state in which the chain cover was installed and the state in which it was removed, and found that the noise was louder with the chain cover in place, and that even if sound-absorbing materials were installed inside the cover, the noise level would not be reduced. Since almost no change was observed, it became clear that the resonance sound inherent to the cover was a bigger problem than the transmitted noise from inside the cover.

Based on the above, the inventors came up with a new and effective method for dealing with sound radiation from the cover.

That is, the most important and most effective method for dealing with sound radiated from the cover is to reduce the resonance sound unique to the cover, and also to take measures against transmitted sound.

To reduce the resonance noise inherent to the cover, there are ways to improve the rigidity by reinforcing it with ribs or increasing the wall thickness, but engine vibrations include many harmonic components of the crankshaft rotation speed (for motorcycle engines, etc.) (The rotation range is also wide), so it is difficult to remove the natural frequency from the vibration range, and the effect is small.

Therefore, it has been considered to simply paste urethane or the like or apply soundproofing paint to the inner surface of the chain cover 1, as shown in FIG. 1, for example.

The chain cover 1 is, for example, a light alloy die-cast product.
A plurality of boss portions 2 provided around the periphery are fastened to a crankcase 4 by bolts 3.

The entire inner surface of the chain cover 1 is provided with a layer 5 of soundproofing paint.

It is preferable to use a soundproofing paint that is as heat- and oil-resistant as possible, but since the temperature of the chain cover 1 is relatively low and there is almost no oil, it is recommended to apply Cemedine or other general soundproofing paint to form the layer 5. Can be done.

However, in this case, there is a problem that not only is it time-consuming to apply the paint, but also that it takes time to dry.

Furthermore, when layer 5 is formed of urethane, the layer cannot be made very thick, so not only will sufficient vibration damping and sound absorption effects not be obtained, but the urethane may peel off or the peeled urethane may become entangled with the chain. There is a fear.

This invention focuses on reducing the above-mentioned resonant sound unique to the cover.The inner surface of the cover is filled with a cushioning material and supported by a porous retainer.The force of the cushioning material significantly damps the vibration of the cover. This makes it possible to significantly reduce the sound radiated from the cover.

According to this method, noise is reduced mainly due to the damping effect of the cover, and together with the sound absorption and sound insulation effects of the cushioning material, it is possible to provide the most effective measure against radiated sound from the cover, and the cover can be manufactured easily. You can wander around.

The present invention will be explained with reference to the drawings as follows.

7 in FIG. 2 is a porous retainer that is shaped to extend along the inner surface of the chain cover 1 at a small distance, and can be obtained by press molding from punched metal or wire cloth, and is provided on the inner surface of the chain cover 1. It is fixed to the chain cover 1 side by bolts 9 at a plurality of boss parts 8 to form a gap 10 at a predetermined interval between it and the inner surface of the chain cover 1, and the gap 10 is filled with glass wool, asbestos, urethane, etc. It is filled with cotton-like cushioning material 10'.

That is, the porous retainer 7 holds down the cushioning material 10' having a predetermined thickness from the inside.

The porous retainer 7 in FIG. 3 is made of punching metal,
A hole 12 is formed by a cylindrical flange portion (slip stopper) 11 that protrudes outward, that is, toward the chain cover 1 side.
The flange portions 11 press the cushioning material 10' toward the chain cover 1 at the portions of the numerous holes 12, thereby preventing the cushioning material 10' from shifting and scattering inward.

When a wire cloth is used as the porous retainer 7, the wires woven vertically and horizontally serve as the anti-slip 11.

As explained above, according to the present invention, in a motorcycle engine in which the chain cover 1 is fixed to the crankcase 4 of an internal combustion engine, a plurality of boss portions 8 are provided on the inner surface of the chain cover 1 exposed inwardly. , a porous retainer 7 is attached to the inner surface of the chain cover 1 through a layer of cotton-like cushioning material 10'.
on the chain cover side surface of the porous retainer 7,
A stopper 11 for the cushioning material 10' that bites into the cushioning material 10' is provided to form a vibration damping structure layer with the cushioning material 10' and the porous retainer 7, and the bolt 9 is connected to the porous retainer 7 and the cushioning material 10'. By screwing the boss part 8 through the
Since the chain cover 1 to which the porous retainer 7 and the buffer material 10' are fixed is attached, noise is reduced due to the damping effect of the cover 1, and in addition to the sound absorption and sound insulation effects of the buffer material, the most effective cover 1 can be used. Not only does it have the advantage of making it possible to take measures against radiated noise and obtain an unparalleled low-noise motorcycle engine, but its simple configuration means that it can be easily put into practical use without increasing costs. Therefore, the chain cover 1 has made a large contribution in the technical field of noise countermeasures.

Furthermore, as an effect based on more specific features of the present invention,
The following items can be highlighted.

(a) A sufficient amount of cushioning material 10' is provided in the gap 10 between the cover 1 and the retainer 7 to effectively damp vibration and absorb sound.
Not only can the retainer 7 reliably limit the protrusion of the cushioning material 10' toward the chain, there is no fear that the cushioning material 10' will peel off or get tangled with the chain.

(b) The retainer 7 has a slip stopper 11 (
If the retainer 7 is made of punching metal, a cylindrical flange,
In the case of a wire cloth, since it has wires woven vertically and horizontally, the cushioning material 10' is reliably held within the gap 10 and will not shift within the gap 10 and cause deviation.

(C) The cushioning material 10' is securely attached to the cover 1 and retainer 7.
Therefore, as the cushioning material 10', not only urethane but also glass wool, asbestos, etc. can be used.
You can use different materials.

(d) The retainer 7 and the buffer material 10' are fixed to the cover 1 by screwing the bolts 9 through the retainer 7 and the buffer material 10' to the boss portion 8 formed on the inner surface of the cover 1. The bolt 9 and the boss portion 8 can also directly prevent the cushioning material 10' from shifting.

Moreover, by providing the boss portion 8, the rigidity can be improved without detracting from the appearance of the cover 1 or increasing its weight.

That is, the bolt 9 and the boss portion δ can have multiple functions.

(e) Bolts 9 are screwed into boss portions 8 on the inner surface of the cover instead of through boss portions 2 of cover 1 to support retainer 7, etc., so retainer 7 is attached and removed when chain cover 1 is attached and removed.
and the cushioning material 10' will not get in the way.

[Brief Description of the Drawings] Fig. 1 is a longitudinal cross-sectional view of a chain cover showing an improved example, Fig. 2 is a longitudinal cross-sectional view of a chain cover to which the present invention is applied, and Fig. 3 is a section A in Fig. 2. It is an enlarged view of. 1... Chain cover, 5... Soundproofing paint layer, 7... Porous retainer, 10'...
... Cushioning material, 11 ... Cylindrical flange part (slip prevention), 12 ... Hole.

Claims (1)

[Scope of utility model registration request] In a motorcycle engine in which a chain cover 1 is fixed to a crankcase 4 of an internal combustion engine, a plurality of boss parts 8 are provided on the inner surface of the chain cover 1 exposed inwardly, and a cotton-like part is provided on the inner surface of the chain cover 1. A porous retainer 7 is arranged through a layer of cushioning material 10', and a cushioning material 10 that bites into the cushioning material 10' is placed on the surface of the porous retainer 7 on the chain cover 1 side.
' by providing a slip stopper 11, forming a vibration damping structure layer with the cushioning material 10' and the porous retainer 7, and screwing the bolt 9 into the boss portion 8 through the porous retainer 7 and the cushioning material 10'. A motorcycle engine characterized in that a chain cover 1 to which a porous retainer 7 and a cushioning material 10' are fixed is attached.