JPS6332347Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an engine noise reduction device applied to an automobile engine or the like.

Generally, in an automobile engine, a pulley is attached to a crankshaft that protrudes from the engine body, and the pulley is used to drive a cooling fan and other auxiliary equipment. However, with such a configuration, there is a problem in that vibrations from the engine body side are transmitted to the pulley via the crankshaft, and noise is likely to be generated from the end face of the pulley.

By the way, as a prior art developed to deal with such inconveniences, as shown in Japanese Utility Model Application Publication No. 55-161956, a sound insulating cover is attached to the end face of a normal pulley attached to a crankshaft. There is. However, in such a structure, if the sound insulation cover is attached directly to the pulley, the vibration of the pulley will be transmitted to the sound insulation cover and noise will be generated from the cover, so it is difficult to attach the cover. Special measures have been taken. That is, in this prior art, a hook is provided on the periphery of the end face of the pulley, and a pawl that engages with the hook is provided on the outer periphery of the sound insulating cover via vibration isolating rubber.
The engaged state of the hook and pawl is maintained by a biasing means such as a spring interposed between the pulley and the sound insulating cover. Therefore, there is a problem that it is difficult to simplify the mounting structure of the sound insulating cover, and there is also a risk that the sound insulating cover will fall off if the vibration isolating rubber or the like loses its elasticity.

In addition, as other prior art that can deal with such problems, as shown in the original specification and drawings of U.S. Pat.
Some damper pulleys include a damper pulley in which a movable member is coaxially supported on the pulley body via an elastic member, and a sound insulating cover fixed to the movable member to cover the end face of the damper pulley. However, this product is lightweight because the sound insulation cover is made of a sheet metal material with a certain thickness.
It is difficult to make this sound insulation cover exhibit a damping effect. Therefore, it is necessary to use a large mass as the floating member, and it is difficult to make the damper pulley more compact. Also,
Since this sound insulation cover has a flat central portion, the sound insulation cover itself tends to cause membrane vibration in the thickness direction. Therefore, there is a possibility that this sound insulating cover itself becomes a new noise source.

Furthermore, as other prior art, JP-A-56-
As shown in No. 165725, a flat plate made of sheet metal,
A damper pulley is also known in which a cover is attached to a floating member, which is made up of a thick part made of synthetic resin or the like attached to the inner surface of the flat plate part. However, since this cover has a thick wall part, the cover itself can also act as a damper, but this thick wall part is provided at and near the center of rotation of the damper pulley. There is. Therefore, unless the mass of this thick portion is made considerably large, the cover cannot exhibit a sufficient damping effect against rotational vibration. Therefore, if an attempt is made to downsize the floating member and have the cover take on part of the role of a mass damper, the weight of the cover will become unreasonably large, and this will hinder the trend toward lighter engines, which has been gaining importance in recent years. It would be contrary to. Further, since this cover is provided with an intake passage that communicates the inside and outside of the cover, it cannot be expected to have a high sound insulation effect.

The present invention was developed by focusing on this situation, and has an attachment part integrated with the damper pulley and the outer periphery of the spherical sound insulation part, and the wall becomes thicker near the attachment part. It is possible to provide an engine noise reduction device that can eliminate all of the above-mentioned disadvantages by cleverly combining the present invention with a sound insulating cover formed in the above-described manner.

An embodiment of the present invention will now be described with reference to FIG.

a rotating shaft protruding from the end face of the engine body 1;
For example, a damper pulley 3 is attached to the protruding end of the crankshaft 2. The damper pulley 3 includes a disc-shaped pulley body 4 whose central boss portion 4a is fixed to the protruding end of the crankshaft 2 using a key 5 and a tightening bolt 6, and an elastic member such as rubber on the outer periphery of the pulley body 4. The ring-shaped floating member 8 is supported through a ring-shaped flexible member 7, and the floating member 8 moves within the elastic range of the elastic member 7.
It is designed to be able to move elastically. A belt groove 11 into which the belt 9 is fitted is provided on the outer periphery of the floating member 8. Also,
A sound insulating cover 12 is fixed to the end face of this floating member 8. The sound insulating cover 12 is a flat cup-shaped cover that substantially entirely covers the end surface of the damper pulley 3. Specifically, the sound insulating cover 12 covers the sound insulating part 1 formed in a spherical shape.
2a, and a mounting portion 12b that is integrally provided on the outer peripheral edge of the sound insulation portion 12a and fixed to the floating member 8. The shape of the sound insulating cover 12 is such that it becomes thicker near the attachment portion. The mounting portion 12b is directly fixed to the end surface of the floating member 8 using a plurality of screws 13.

If it has such a configuration, the sound insulation cover 1
2 is supported by the floating member 8 of the damper pulley 3, so the sound insulating cover 12 itself also functions as a mass damper. In particular, the sound insulating cover 12 is made thicker near the mounting portion 12a, so that it can maximize its function as a mass damper.
That is, compared to the cover of the prior art described in the above-mentioned Japanese Utility Model Publication No. 56-165725, which has a thick wall portion at and around the center of rotation of the crankshaft 2, the sound insulation cover of the present invention No. 12 indicates that the mass tends to be concentrated in the outer peripheral portion away from the center of rotation. Therefore, if this sound insulating cover 12 is used, a greater damping effect can be obtained with a lighter weight than in the case of using the cover of the prior art. In other words, if they have the same mass, the sound insulation cover 12 of the present invention will exhibit a much higher damping effect than the cover of the prior art, and the aim is to achieve the same level of damping effect. If so, the sound insulation cover 12 of the present invention is better.
It is much lighter than the prior art covers. Therefore, the sound insulating cover 12 can also serve as a part of the mass damper without going against the weight reduction, and the floating member 8 can be made smaller and the damper pulley 3 can be made more compact. As is well known, this type of pulley is generally placed in a narrow space near the engine body, and when an engine is retrofitted, other pulleys are placed adjacent to it. That will happen. Therefore, the effect of being able to make this type of damper pulley more compact without increasing its weight or reducing its performance is extremely significant.

Then, the sound insulation part 12a of this sound insulation cover 12
Since it does not have a through hole, it can effectively block transmitted sound. Therefore, the engine body 1
The side vibration is transmitted to the pulley body 4 of the damper pulley 3 via the crankshaft 2, and this pulley body 4
Even if noise is generated from the end face of the sound insulating cover 12, the sound insulation cover 12 can effectively prevent the noise from dissipating to the outside. Furthermore, by attaching the sound insulation cover 12 to the floating member 8, various vibrations including torsional vibration transmitted from the crankshaft 2 to the pulley body 4 are difficult to be transmitted to the sound insulation cover 12. Therefore, there is no inconvenience that the sound insulating cover 12 itself vibrates and emits sound. especially,
The sound insulating cover 12 has a spherical sound insulating part 12a, and the wall becomes thicker near the attachment part 12b, so that the sound insulating cover 12 has high rigidity and is difficult to deform in the thickness direction. Therefore, the possibility that the sound insulating cover 12 causes membrane vibration is also significantly reduced. Therefore, with such a structure, the noise radiated from the damper pulley 3 portion can be suppressed very effectively.

Furthermore, if the sound insulation cover 12 is directly fixed to the floating member 8 of the damper pulley 3 using the screws 13 or the like in this way, there is an advantage that the mounting structure of the sound insulation cover 12 becomes extremely simple. Furthermore, it is possible to reliably eliminate the inconvenience of the sound insulating cover falling off due to fatigue of the vibration isolating rubber, which is the case with conventional systems in which the sound insulating cover is attached to the pulley via vibration isolating rubber. This effect can be obtained.

It should be noted that the structure of the damper pulley is of course not limited to that of the above embodiment.
It may be as shown in the figure. That is,
The damper pulley 3' shown in FIG. 2 has a floating member 8' supported on the inner periphery of a pulley body 4' via an elastic member 7'.

Furthermore, the rotating shaft is not limited to a crankshaft, and may be, for example, a balance shaft.

Since the present invention has the above-mentioned configuration, by having the sound insulation cover with a thick outer mounting part play a part of the role of a mass damper, the damper pulley can be mounted without increasing the weight. It is possible to obtain the special effect of being able to achieve compactness, and in addition, it is possible to extremely effectively suppress the noise generated from the pulley part due to the vibration of the rotating shaft, and it also provides the sound insulation necessary for soundproofing. The cover mounting structure can be simplified and the mounting strength can be improved.Furthermore, by making the relatively thin sound insulation part spherical, the sound insulation cover itself will vibrate and become a new noise source. Therefore, it is possible to provide an engine noise reduction device that can effectively prevent this inconvenience.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a schematic sectional view showing another embodiment of the present invention. 1... Engine body, 2... Rotating shaft (crankshaft), 3, 3'... Damper pulley, 4, 4'...
Pulley body, 7, 7'...Elastic member, 8, 8'...
Floating member, 12... Sound insulation cover, 12a... Sound insulation part, 12b... Mounting part.

Claims (1)

[Scope of utility model registration request] A damper pulley includes a pulley body that rotates together with a rotating shaft protruding from the engine body, and a floating member is coaxially supported by the pulley body via an elastic member, and a and a sound insulating cover fixed to the floating member, the sound insulating cover comprising:
The sound insulating cover is made of a sound insulating part having a spherical shape and has no through holes, and a mounting part that is integrally provided on the outer periphery of the sound insulating part and fixed to the floating member, and the shape of the sound insulating cover is adjusted according to the shape of the mounting part. A noise reduction device for an engine, characterized in that the wall becomes thicker near the bottom.