JP2021063475A - Cover member for engine - Google Patents

Abstract

To provide a technology that inhibits a standing wave in an engine room while reducing the weight of a vehicle.SOLUTION: A cylinder head cover 10 includes: a first wall part 41 covering at least a part of an engine of a vehicle; and a second wall part 43 which is disposed spaced a predetermined distance apart from the first wall part 41 to the engine room DR side and forms a volume chamber S with the first wall part 41. The second wall part 43 is formed with through holes 45 which open opposite to a space in the engine room ER from the volume chamber S.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cover member for an engine such as a cylinder head cover, a front cover, and an oil pan, which is provided with a noise reducing device for an engine room.

In recent years, there has been an increasing demand for a technology that solves the conflicting problems of quietness in the vehicle interior and high engine output for the purpose of improving comfort in the vehicle interior. For example, an instrument panel is provided in the passenger compartment. It is known that a sound absorbing structure using an elastic urethane foam resin is provided in the instrument panel to significantly suppress the noise generated from the engine from entering the vehicle interior. (For example, Patent Document 1).

Japanese Unexamined Patent Publication No. 11-34761

By the way, the noise reduction technology using the foamable urethane resin can also be applied in the engine room. Conventionally, it is known that a standing wave is generated in an engine room. The standing wave is generated as noise in the space between the engine body and the wall surface of the engine room, for example, in the engine room.

Consideration was given to reducing the generated noise by arranging the foamable urethane resin in the engine room. However, by using the foamable urethane resin, the number of parts increases, the cost increases, the weight of the vehicle increases, and the fuel consumption decreases.

Further, in muffling using a foam such as urethane, it is difficult to control the muffling frequency, and it is particularly difficult to mute low frequencies.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for suppressing a standing wave in an engine room while suppressing the weight of a vehicle.

In order to solve the above problems, the engine cover member according to the present invention has a first wall portion that covers at least a part of the engine of the vehicle and a predetermined distance on the engine room side with respect to the first wall portion. The second wall portion is provided with a second wall portion which is arranged so as to form a volume chamber between the first wall portion and the first wall portion, and the second wall portion faces the space in the engine room from the volume chamber. It is characterized in that a plurality of through holes are formed to be opened. According to this aspect, the cover member for the engine can be provided with a sound deadening function using a space, which can contribute to the weight reduction of the vehicle.

Further, the first wall portion and the second wall portion may be joined and integrated. According to this aspect, it is possible to obtain a cover member having an integrated sound deadening function.

Further, a partition wall for partitioning the volume chamber to form a plurality of volume chambers may be further provided. According to this aspect, the volume chamber can be divided into a plurality of volume chambers, and the vibration resistance strength with respect to the second wall portion can be increased.

Further, different numbers of the through holes may be passed through the plurality of volume chambers. According to this aspect, one engine cover member can exert a muffling effect on noise of different frequencies.

Further, it may be at least one of a head cover, a front cover and an oil pan. According to this aspect, it can be attached to various parts of the engine cover member and can exhibit high versatility.

According to the present invention, it is possible to suppress the standing wave in the engine room while suppressing the weight of the vehicle, and it is possible to mute the standing wave of various frequencies including low frequencies.

It is the schematic of the engine room which shows the arrangement of the cover member (head cover) of this invention. It is the schematic which shows the structure of an engine. It is the schematic sectional drawing of the engine for demonstrating the structure of a head cover. It is a perspective view of the cover member (head cover) of this invention and the noise reduction device of a cover member. It is a graph which shows the muffling effect of the noise reduction apparatus which concerns on Examples 1 to 3. It is the schematic which shows the noise reduction apparatus which concerns on modification 1. It is the schematic which shows the noise reduction apparatus which concerns on modification 2. It is the schematic which shows the noise reduction apparatus which concerns on modification 3.

A preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of the inside of the engine room ER of a vehicle equipped with the engine 100. In the present embodiment, the cover member provided with the noise reduction device is the head cover 10, which is mounted on the engine 100 and is standing in the space between the engine 100 and the bonnet BC in the engine room ER of the vehicle. Mainly reduces waves.

FIG. 2 is a schematic view showing the configuration of the engine 100. The engine 100 is roughly composed of a cylinder block 120, a cylinder head 110, a head cover 10, a front cover 20, and an oil pan 30. Of these, the head cover 10, the front cover 20, and the oil pan 30 are made of, for example, resin, and these are referred to as cover members. The noise reduction device 40 according to the present invention is integrally provided on the head cover 10.

FIG. 3 is a schematic cross-sectional view of the engine 100 for explaining the configuration of the head cover 10 including the noise reduction device 40. The head cover 10 is located in the engine room ER on the side of the engine 100 facing the bonnet BC. The head cover 10 is arranged above the cylinder head 110 so that the opening faces the lower cylinder head 110. The head cover 10 covers the upper surface of the cylinder head 110 of the engine 100. The head cover 10 is attached to the cylinder head 110 by fasteners such as bolts.

The front cover 20 is located in the engine room ER on the side of the engine 100 facing the front of the vehicle. The front cover 20 is attached to the front ends of the cylinder head 110 and the cylinder block 120 so that the openings face, for example, the drive system by the camshaft. The front cover 20 is attached to the cylinder head 110 and the cylinder block 120 by fasteners such as bolts.

The oil pan 30 is an oil receiving cover provided on the side of the cylinder block 120 opposite to the head cover 10 in the engine room ER. The oil pan 30 stores oil from equipment that uses oil in the engine 100.

The head cover 10 covers the cylinder head 110 and includes an oil mist separator and the like, but these are omitted in the drawings and are shown schematically. The head cover 10 is provided with a noise reduction device 40.

The head cover 10 is arranged on the side of the engine room ER with a predetermined distance from the first wall portion 41, which is a head cover main body that covers the engine of the vehicle, and the first wall portion 41. A second wall portion 43 that forms a volume chamber S between the two walls is provided. The second wall portion 43 is formed with a plurality of through holes 45 that open from the volume chamber S toward the space in the engine room ER. Hereinafter, the configuration of the head cover 10 will be specifically described.

FIG. 4 is a perspective view of the head cover 10 and shows the head cover 10 in a partial cross section. The head cover 10 is made of a resin such as polyamide and includes a noise reduction device 40. The noise reduction device 40 is integrated with the head cover 10. The noise reduction device 40 can be regarded as a part of the head cover 10. The first wall portion 41 seals and covers the cylinder head 110 in the head cover 10. The first wall portion 41 has a substantially rectangular outer shape in a plan view. The cross-sectional shape of the first wall portion 41 when viewed from the side surface is substantially U-shaped.

The second wall portion 43 covers the first wall portion 41 at least partially from the outside on the side of the engine room ER. In the present embodiment, the second wall portion 43 covers a part of the first wall portion 41, but the first wall portion 41 may be entirely covered. The first wall portion 41 is integrally joined to the second wall portion 43 by vibration welding or the like. The second wall portion 43 has a side portion 43a and an opposing portion 43b. The side portion 43a projects from the outer surface 41a of the first wall portion 41 facing the engine room ER of the vehicle toward the inside of the engine room ER. One end of the side portion 43a is integrally connected to the first wall portion 41.

The facing portion 43b is provided at the other end of the side portion 43a. The facing portion 43b faces the outer surface 41a of the first wall portion 41. The facing portion 43b is separated from the first wall portion 41 by the height of the side portion 43a. The volume chamber S is defined by the outer surface 41a of the first wall portion 41, the side portion 43a, and the facing portion 43b. The second wall portion has a plurality of through holes 45 in the facing portion 43b. The volume chamber S and the engine room ER communicate with each other through the through hole 45.

The noise reduction device 40 further includes a partition rib (partition wall) 50. The partition rib 50 partitions the volume chamber S to form a plurality of volume chambers S1, S2, S3, and S4. The partition rib 50 extends from the inner surface 43c of the facing portion 43b toward the outer surface 41a of the first wall portion 41, and is coupled to the outer surface 41a of the first wall portion 41 by vibration welding or the like. The partition rib 50 is formed in a cross shape in a plan view. The partition rib 50 divides the volume chamber S into four volume chambers S1, S2, S3, and S4 substantially equally.

The volume chambers S1, S2, S3, and S4 each have the same diameter and the same number of through holes 45. That is, the same number of through holes 45 are formed in the portions of the facing portions 43b facing each of the volume chambers S1, S2, S3, and S4.

The noise reduction device 40 having the above configuration has a Helmholtz structure. The Helmholtz structure is composed of a first wall portion 41, a second wall portion 43 having a through hole 45, and a volume chamber S defined by both wall portions 41 and 43. In this example, the cross-sectional shape of the volume chamber S is rectangular, but various shapes are possible. For example, the volume chamber S is designed so that the cross-sectional shape is trapezoidal or triangular so that the second wall portion 43 is arranged with a predetermined inclination angle with respect to the first wall portion 41, and the engine room. It is possible to appropriately change the facing angle of the second wall portion 43 with respect to the space of the ER and the volume of the volume chamber S.

The volume chambers S (S1, S2, S3, S4) suppress the sound propagating air from the engine room ER by the principle of Helmholtz resonance. When an external pressure (noise) acts on the head cover 10 due to a standing wave in the engine room ER, air tries to enter the volume chambers S1 to S4 through the through hole 45. The air in the volume chambers S1 to S4 tends to push out the air entering the volume chambers S1 to S4 from the engine room ER through the through hole 45. When air invades the engine room ER from the volume chambers S1 to S4, a negative pressure is generated in the volume chambers S1 to S4 by the amount of the invaded air. Due to the generated negative pressure, a force is generated to return the air in the engine room ER into the volume chambers S1 to S4.

The above phenomenon occurs in each through hole 45. Repeated intrusion and leaching of air in each through hole 45 causes air to come into contact with the through hole 45 to cause friction, and acoustic energy is consumed by the noise reduction device 40.

Here, the relationship between the number of through holes 45 and the sound pressure level [dB] will be described based on a plurality of Examples 1 to 3 of the noise reduction device according to the present invention. FIG. 5 is a graph showing the muffling effect of the noise reducing device according to the embodiment.

The specifications of Examples 1 to 3 and Comparative Examples are as follows.
<Example 1>
Total volume of volume chamber: 32cc
Number of volume chamber compartments: 4 Number of through holes in each compartment: 9 Hole diameter: φ4 mm

<Example 2>
Total volume of volume chamber: 32cc
Number of volume chamber compartments: 4 Number of through holes in each compartment: 13 Hole diameter: φ4 mm

<Example 3>
Total volume of volume chamber: 32cc
Number of volume chamber compartments: 4 Number of through holes in each compartment: 25 Hole diameter: φ4 mm

<Comparative example 1>
Total volume of volume chamber: 32cc
Number of volume chamber compartments: 4 Number of through holes in each compartment: 0

Noise was input to the facing portions 43b of Examples 1 to 3 and Comparative Examples having the above specifications while changing the frequency from a predetermined interval to a frequency of 1000 to 3000 Hz. The sound pressure level was measured between the facing portion 43b and the noise source.

In the comparative example, the sound pressure level changed periodically with respect to the noise frequency of 1000 to 3000 Hz, and the peak value was only measured periodically. On the other hand, according to the noise reduction device 40 having the specifications of the first embodiment, the sound pressure level sharply dropped at a frequency of around 1500 Hz. Further, according to the noise reduction device 40 having the specifications of the second embodiment, the sound pressure level sharply dropped around the frequency exceeding 1700 Hz. Further, according to the noise reduction device 40 having the specifications of the third embodiment, the sound pressure level drops sharply around 2000 Hz.

In Examples 1 to 3, it was found that the sound pressure level was reduced at a specific frequency. That is, it was found that by changing the number of through holes 45, the muffling effect is exhibited for noise of different frequencies.

Further, since the noise reduction device 40 at least partially fills the space (volume) in which the standing wave is generated between the head cover 10 and the bonnet BC, the generation of the standing wave can be suppressed. The noise reduction device 40 is a mechanism that utilizes the principle of Helmholtz resonance, and can appropriately exert the sound attenuation effect in the engine room ER.

Further, in the noise reduction device 40, since the partition rib 50 is coupled to the side portion 43a and the facing portion 43b, it is possible to effectively suppress the vibration of the entire second wall portion 43 and the second wall portion. It is possible to suppress the generation of noise caused by the vibration of 43.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and includes all aspects included in the concept of the present invention and the scope of claims. In addition, each configuration may be selectively combined as appropriate so as to achieve at least a part of the above-mentioned problems and effects. Further, for example, the shape, material, arrangement, size, etc. of each component in the above embodiment can be appropriately changed depending on the specific usage mode of the present invention. For example, in the above embodiment, the noise reduction device 40 is integrally provided on the head cover 10, but can be provided on any of the head cover 10, the front cover 20, and the oil pan 30 to provide a standing wave. One or a plurality may be provided according to the generation position.

FIG. 6 is a schematic view showing the noise reduction device 40A according to the first modification. In the above embodiment, the same number of through holes 45 are provided in the portions of the facing portions 43b facing the volume chambers S1, S2, S3, and S4, which are divided into four by the partition rib 50. The noise reduction device 40A is provided with a different number of through holes 45.

With the noise reduction device 40A, a plurality of muffling frequencies can be set in one noise reduction device 40A. As a result, noise in a wider band (broadband) frequency can be effectively muted.

FIG. 7 is a schematic view showing the noise reduction device 40B according to the second modification. In the above embodiment, the shape of the partition rib 50 is formed in a cross shape in a plan view, but the shape of the partition rib may be appropriately changed based on the target muffling frequency and layout. In the noise reduction device 40B, the partition rib 50 is formed in a T shape in a plan view. In this case, the volume chamber S is divided into two volume chambers S1 and S2 having substantially the same volume and one volume chamber S5 having substantially the same volume as the combined volume of the two volume chambers S1 and S2. The noise reduction device 40B can adjust the volume of the volume chamber S in order to adjust the muffling frequency.

FIG. 8 is a schematic view showing the noise reduction device 40C according to the third modification. In the above embodiment, the noise reduction device 40 has the partition rib 50, but the volume chamber S does not have to be divided as in the noise reduction device 40C.

The head cover 10 provided with the noise reduction devices 40A, 40B, and 40C of any of the above-described modifications 1 to 3 has a noise reduction effect as in the case of the head cover 10 provided with the noise reduction device 40 according to the above embodiment. Can be played.

Further, in the above embodiment, the through hole 45 is formed in the facing portion 43b in the second wall portion 43, but may be formed in at least one of the side portion 43a and the facing portion 43b.

Further, in the above embodiment, the second wall portion 43 is integrally formed with the first wall portion 41 by being coupled to the first wall portion 41 by vibration welding or the like, but the first wall portion 41 and the second wall portion 43 May be formed separately. In this case, the noise reduction device 40 can be easily retrofitted to the existing cover member as a separate device by using a connecting means such as a snap fit.

10 head cover, 20 front cover, 30 oil pan, 40 noise reduction device, 41 first wall, 41a outer surface, 43 second wall, 43a side, 43b facing, 45 through hole, 50 partition wall, 100 engine, 110 cylinder head, 120 cylinder block, ER engine room, S volume room

Claims (5)

The first wall that covers at least part of the vehicle's engine,
A second wall portion which is arranged on the engine room side with a predetermined distance from the first wall portion and forms a volume chamber between the first wall portion and the first wall portion.
With
A cover member for an engine, characterized in that a plurality of through holes that open from the volume chamber to the space in the engine chamber are formed in the second wall portion. The cover member for an engine according to claim 1, wherein the first wall portion and the second wall portion are joined and integrated. The cover member for an engine according to claim 1 or 2, further comprising a partition wall for partitioning the volume chamber to form a plurality of volume chambers. The cover member for an engine according to claim 3, wherein a different number of through holes are passed through the plurality of volume chambers. The cover member for an engine according to any one of claims 1 to 4, wherein the cover member is at least one of a head cover, a front cover, and an oil pan.

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