JP2011256857A - Sound insulation structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently reduce noises coming from a noise emitting source.SOLUTION: An oil pan cover 2 is installed so as to fully cover an oil pan 13 via an air layer 21. The air layer 21 between the oil pan cover 2 and the oil pan 13 is divided into a plurality of spaces 5a to 5aa by partition members 3a to 3h and 4a to 4j. A plurality of granular materials are enclosed with at least one of the spaces. The oil pan cover 2 is composed of a plurality of planes 2a to 2i, which have been combined.

Description

  The present invention relates to a sound insulation structure installed in the vicinity of a noise generating source such as an oil pan for storing lubricating oil for an engine of a construction vehicle or the like.

  An oil pan that stores lubricating oil for an engine of a construction vehicle or the like is usually made of a thin metal plate, and vibrations are transmitted from the engine due to driving of the engine to generate noise. Usually, the acoustic power of the oil pan is dominant in engine noise, and its reduction is essential. Therefore, as a method for reducing the vibration of the oil pan itself, improvement of rigidity, weight increase, use of a damping steel plate, and a device for mounting have been proposed. However, there are many cases where these cannot provide a sufficient noise reduction effect, and it has been proposed to reduce the noise by attaching a sound insulation cover to the oil pan.

  In Patent Document 1, the vibration of the sounding body is attenuated by bringing the damping material into contact with the sounding body, and the sound insulation cover and the sounding body are separated from each other by the Helmholtz resonance principle formed by the chamber and the through hole formed by the damping material. A sound insulation structure for attenuating noise in the gap is disclosed.

JP 2000-45789 A

  However, Helmholtz's resonance principle is basically a way to reduce single frequency noise. Therefore, when the engine speed changes, the Helmholtz resonance principle cannot be used, and the noise reduction effect is reduced. Therefore, a method of forming a Helmholtz resonator having a structure having a plurality of through-holes and chambers having different aperture ratios to exhibit a sound absorption effect in a wide band is conceivable, but if a Helmholtz resonator corresponding to each frequency is made, The structure becomes so complex that it is not realistic. Further, since the sound absorption area for each frequency is reduced, the sound absorption effect itself is also reduced.

  Another possible method is to insert a porous sound-absorbing material, such as glass wool, between the oil pan and the sound-insulating cover, but the sound-absorbing performance is expected to deteriorate in poor environments around the engine, such as heat and oil leaks. It is not effective.

  An object of the present invention is to provide a sound insulation structure capable of sufficiently reducing noise from a noise generation source.

  The sound insulation structure according to the present invention includes a sound insulation cover attached to the noise generation source so as to cover at least a part of the noise generation source through the air layer, a partition member that partitions the air layer into a plurality of spaces, A plurality of granular bodies enclosed in at least one of a plurality of spaces, and the sound insulation cover is configured by combining a plurality of planes.

  According to the above configuration, the noise generated from the noise generation source is shielded by the sound insulation cover, but the sound insulation cover vibrates due to vibration propagated from the attachment portion of the sound insulation cover to the noise generation source and vibration propagated through the air layer. . However, since the plurality of granular materials vibrate in response to the vibration of the sound insulating cover, the vibration of the sound insulating cover is attenuated over a wide frequency range by contact and friction between the granular materials. As a result, the vibration of the sound insulation cover is reduced and the radiation sound from the sound insulation cover is reduced, so that the sound insulation performance is improved. Further, when the sound wave propagates between the granular bodies, the sound wave is attenuated, and the sound pressure excitation force to the sound insulation cover is also reduced. As a result, since the vibration of the sound insulation cover is reduced, the sound insulation performance is improved. Moreover, the partition of the granular material can be eliminated by partitioning the air layer into a plurality of spaces. Moreover, the vibration suppression effect can be exhibited at a desired location by enclosing the granular material in a specific space. Moreover, since the rigidity of the sound insulation cover is lower when the sound insulation cover is composed of a plurality of planes than when the sound insulation cover is composed of a curved surface, the radiation efficiency (conversion efficiency from vibration to sound) of the sound insulation cover is lowered. Thereby, since re-radiation from a sound insulation cover reduces, sound insulation performance can be improved. Therefore, the noise from the noise generation source can be sufficiently reduced.

  Further, in the sound insulation structure according to the present invention, the partition member may be formed by processing at least one of the noise generation source and the sound insulation cover. According to said structure, since it is not necessary to add a member separately by forming a partition member by uneven | corrugated processing, the reduction of a number of parts, the reduction of a manufacturing process, and the cost can be aimed at.

  The sound insulation structure according to the present invention further includes a vibration isolating member having a vibration isolating property provided between the noise generating source and the sound insulating cover together with the partition member, and the noise generating source and the sound insulating unit. The cover may be combined at a plurality of locations via the partition member and the vibration isolating member. According to the above configuration, by connecting the noise generation source and the sound insulation cover at a plurality of locations via the partition member and the vibration isolation member, the durability of the sound insulation structure can be improved in a severe vibration environment. Can do. Further, by connecting the noise generation source and the sound insulation cover via the vibration isolation member, it is possible to suppress a decrease in the sound insulation performance due to vibration transmission from the noise generation source.

  In the sound insulation structure of the present invention, at least a part of the end of the sound insulation cover contacts the noise generation source so as to cover at least a part of the gap between the end of the sound insulation cover and the noise generation source. May have been. According to the above configuration, at least a part of the end of the sound insulation cover is brought into contact with the noise generation source, so that at least a part of the gap between the end of the sound insulation cover and the noise generation source is covered with the end of the sound insulation cover. Therefore, the leakage of noise from the gap between the end portion of the sound insulation cover and the noise generation source is suppressed. Further, as the noise source vibrates, a relative displacement occurs between the noise source and the sound insulation cover, and friction occurs at the contact portion. Therefore, the vibration energy is converted into heat energy, and the vibration is attenuated. . Thereby, the sound insulation performance can be improved. Moreover, the amount of friction generation can be controlled by widening or narrowing the area of the end portion of the sound insulation cover that is brought into contact with the noise generation source.

  Further, in the sound insulation structure according to the present invention, one end is attached to the noise generation source and the other end is attached to the sound insulation cover, respectively, and covers at least a part of a gap between the end of the sound insulation cover and the noise generation source. A shielding member may be further included. According to said structure, since at least one part of the clearance gap between the edge part of a sound-insulation cover and a noise generation source is covered with a shielding member, it is suppressed that the noise which leaked from this clearance | interval leaks outside. Thereby, the sound insulation performance can be improved.

  In the sound insulation structure according to the present invention, the shielding member may have vibration damping properties. According to said structure, since the vibration transmitted to a sound insulation cover from a noise generation source via a shielding member is attenuate | damped by the damping property which a shielding member has, the resonance of a sound insulation cover is suppressed. Thereby, the sound insulation performance can be improved.

  In the sound insulation structure according to the present invention, the plurality of granular materials may be enclosed in the space in a state of being put in a bag. According to the above configuration, by enclosing a plurality of granular materials in a space in a bag, it becomes easy to enclose the granular materials at the time of manufacturing, so that the manufacturing cost can be reduced, Variations in the vibration control effect due to the granular material can be reduced.

  In the sound insulation structure according to the present invention, the sound insulation cover may be attached to the noise generation source via an elastic body. According to said structure, the vibration of a sound insulation cover can be reduced by attaching a sound insulation cover to a noise generation source via an elastic body.

  In the sound insulation structure according to the present invention, the elastic body may be a spring. According to said structure, by attaching a sound insulation cover to a noise generation source via a spring, the radiated sound radiated | emitted from a sound insulation cover by the vibration transmission from a noise generation source to a sound insulation cover can be reduced.

  According to the sound insulation structure of the present invention, the vibration of the sound insulation cover is reduced due to contact and friction between the granular materials, and the sound emitted from the sound insulation cover is reduced, so that the sound insulation performance is improved. Further, when the sound wave propagates between the granular bodies, the sound wave is attenuated and the sound pressure excitation force to the sound insulation cover is also reduced, so that the vibration of the sound insulation cover is reduced and the sound insulation performance is improved. Moreover, by partitioning the air layer into a plurality of spaces, it is possible to eliminate the unevenness of the granular material, and it is possible to exert a vibration damping effect at a desired location by enclosing the granular material in a specific space. Moreover, since the re-radiation from the sound insulation cover is reduced, the sound insulation performance can be improved when the sound insulation cover is composed of a plurality of planes rather than the curved surface. Therefore, the noise from the noise generation source can be sufficiently reduced.

It is a schematic side view which shows a construction vehicle. It is a schematic perspective view of an oil pan and an oil pan cover. It is a schematic sectional drawing of an oil pan and an oil pan cover. It is a schematic sectional drawing of an oil pan and an oil pan cover. It is a schematic sectional drawing of an oil pan and an oil pan cover. It is a schematic sectional drawing of an engine and a sound insulation cover. It is an enlarged view of the principal part B of FIG. It is an expansion perspective view of the principal part B of FIG. It is an enlarged view of the principal part B of FIG. It is a graph which shows the relationship between a frequency and sound insulation performance. It is a graph which shows the relationship between a frequency and sound insulation performance. It is a schematic sectional drawing of an engine and a sound insulation cover. It is an expansion perspective view of the principal part C of FIG. It is an enlarged view of the principal part C of FIG.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
(Configuration of construction vehicles)
As shown in FIG. 1, the sound insulation structure 1 according to the present embodiment is provided in a construction vehicle 11 such as a hydraulic excavator. The construction vehicle 11 is provided with an engine 12, an oil pan 13 for storing engine oil, and an exhaust pipe (not shown) through which exhaust gas discharged from the engine 12 passes. Then it vibrates and generates noise. The sound insulation structure 1 covers the entire surface of the oil pan 13 that is a noise generation source via the air layer 21 to insulate the noise from the oil pan 13.

(Configuration of sound insulation structure)
As shown in FIG. 2, the sound insulation structure 1 includes a plurality of oil pan covers (sound insulation covers) 2 attached to the oil pan 13 and a plurality of air layers 21 so as to cover the entire oil pan 13 through the air layer 21. Partition member 3 (3a to 3h) and partition member 4 (4a to 4j) for partitioning into space 5 (5a to 5aa). The oil pan cover 2 only needs to cover at least a part of the oil pan 13.

  The oil pan 13 has a curved surface as shown in FIG. On the other hand, the oil pan cover 2 is configured by combining nine planes 2a to 2i. Specifically, the flat surfaces 2 a to 2 f constitute the side surface of the oil pan cover 2. The planes 2g to 2i constitute the bottom surface of the oil pan cover 2. Each of the flat surfaces 2a to 2i has a flat portion having a length of ½ or more of the wavelength of the bending wave determined based on the frequency of noise generated from the oil pan 13. In this way, the oil pan cover 2 is less rigid than the oil pan cover 2 configured by a curved surface, and the rigidity of the oil pan cover 2 is reduced, and the wavelength of the bending wave propagating in the oil pan cover 2 is reduced. Since it becomes short, the radiation efficiency (conversion efficiency from vibration to sound) of the oil pan cover 2 is lowered.

  The eight partition members 3 a to 3 h provided on the bottom surface of the oil pan cover 2 and the ten partition members 4 a to 4 j provided on the side surface of the oil pan cover 2 divide the air layer 21 into the 27 spaces 5 a to 5. It is divided into 5aa. Specifically, the air layer 21 is divided into 21 spaces 5a to 5u by two partition members 3a and 3b and six partition members 3c to 3h intersecting with these, and five partition members. The air layer 21 is partitioned into three spaces 5v to 5x by 4a to 4e, and the air layer 21 is partitioned into three spaces 5y to 5aa by five partition members 4f to 4j.

  As shown in FIG. 3 which is an AA cross section of FIG. 2, the sound insulation structure 1 has a plurality of granular bodies 6 enclosed in a plurality of spaces 5d, 5e, 5f, 5w, 5z. The plurality of granular bodies 6 are enclosed in the spaces 5d, 5e, 5f, 5w, and 5z in a state of being put in a bag. The granular material 6 may be enclosed in at least one of the plurality of spaces 5, and may be enclosed in a space other than the spaces 5d, 5e, 5f, 5w, and 5z. The plurality of granular materials 6 are preferably enclosed in a specific space in order to exert a vibration damping effect at a desired location of the oil pan cover 2.

  Here, the granular material 6 may be anything as long as it satisfies the conditions that it is heavy, inexpensive, has a uniform shape, and does not change with time. Among them, reduced iron pellets, slag (eg, blast furnace slow-cooled slag, blast furnace granulated slag, converter slag, electric furnace slag, etc.), reduced pellets, onions, sintered steel, which contain a large amount of iron and have a high specific gravity. Cold pellets (iron powder, dust, flash ash or the like solidified with cement by pellets) or the like is preferable as the granular material 6. In particular, the reduced pellets are preferable for the granular material 6 because they are available at low cost, have a uniform particle size, are fired, have a low water content, and have a high specific gravity.

  The sound insulation structure 1 has a vibration isolating member 7 having a vibration isolating property provided between the oil pan 13 and the oil pan cover 2 together with the partition members 3a and 3b. Specifically, the vibration isolating member 7 is provided between the partition members 3a and 3b and the oil pan cover 2, and between the partition members 3a and 3b and the oil pan 13, respectively. The vibration isolation member 7 is, for example, rubber, sponge, or metal spring. The oil pan 13 and the oil pan cover 2 are coupled at a plurality of locations via the partition members 3 a and 3 b and the vibration isolation member 7. The vibration isolating member 7 may be provided only between the partition members 3a and 3b and the oil pan cover 2, or may be provided only between the partition members 3a and 3b and the oil pan 13. Good. The same applies to the other partition members 3c to 3h (see FIG. 2).

  In addition, in the attaching portion 24 of the oil pan cover 2 to the oil pan 13, the oil pan cover 2 is attached to the oil pan 13 via the elastic body 8 by bolts 22 and nuts 23. Specifically, in a state where the oil pan cover 2 is sandwiched between two elastic bodies 8, a bolt 22 that penetrates the elastic body 8, the oil pan cover 2, the elastic body 8, and the oil pan 13 in this order, and the bolt The oil pan cover 2 is attached to the oil pan 13 by a nut 23 that is screwed onto the oil pan 22. In the state where the oil pan 13 is sandwiched between the two elastic bodies 8, the oil pan cover 2, the elastic body 8, the oil pan 13, and the elastic body 8 are penetrated in this order, and the bolts 22 are screwed together. The oil pan cover 2 may be attached to the oil pan 13 by the nut 23 that performs. The elastic body 8 is, for example, rubber or sponge.

  The noise generated from the oil pan 13 is shielded by the oil pan cover 2, but the oil pan cover 2 vibrates due to vibration propagated from the mounting portion 24 of the oil pan cover 2 to the oil pan 13 and vibration propagated through the air layer 21. To do. However, since the plurality of granular bodies 6 vibrate according to the vibration of the oil pan cover 2, the vibration of the oil pan cover 2 is attenuated over a wide frequency range due to contact and friction between the granular bodies 6. As a result, the vibration of the oil pan cover 2 is reduced and the radiation sound from the oil pan cover 2 is reduced, so that the sound insulation performance is improved. Further, when the sound wave propagates between the granular bodies 6, the sound wave is attenuated and the sound pressure excitation force to the oil pan cover 2 is also reduced. As a result, since the vibration of the oil pan cover 2 is reduced, the sound insulation performance is improved.

  In addition, by partitioning the air layer 21 into the plurality of spaces 5, the unevenness of the granular material 6 can be eliminated. Moreover, the vibration suppression effect can be exhibited in a desired location by enclosing the granular material 6 in a specific space.

  Moreover, since the rigidity of the oil pan cover 2 is lower when the oil pan cover 2 is composed of a plurality of planes 2a to 2i than when the oil pan cover 2 is composed of a curved surface, the radiation efficiency of the oil pan cover 2 (from vibration to sound) Conversion efficiency). Thereby, since re-radiation from the oil pan cover 2 is reduced, the sound insulation performance can be improved.

  Therefore, the noise from the oil pan 13 can be sufficiently reduced.

  In addition, by connecting the oil pan 13 and the oil pan cover 2 at a plurality of locations via the partition members 3a and 3b and the vibration isolating member 7, the durability of the sound insulation structure 1 is improved in a severe vibration environment. Can be made. In addition, by connecting the oil pan 13 and the oil pan cover 2 via the vibration isolating member 7, it is possible to suppress a decrease in sound insulation performance due to vibration transmission from the oil pan 13.

  Moreover, since the enclosure of the granular material 6 at the time of manufacture becomes easy by enclosing the several granular material 6 in the space 5 in the state put in the bag, while being able to reduce manufacturing cost, a granular material 6 can reduce variations in the vibration control effect.

  Moreover, the vibration of the oil pan cover 2 can be reduced by attaching the oil pan cover 2 to the oil pan 13 via the elastic body 8.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. The sound insulation structure 51 of the present embodiment is formed by processing the oil pan cover 2 with unevenness, as shown in FIG. 4 which is a cross section taken along the line AA of FIG. 2, and the partition members 53a and 53b and the partition members 54a and 54f. This is different from the sound insulation structure 1 of the first embodiment.

  The partition members 53a and 53b correspond to the partition members 3a and 3b of the first embodiment, respectively, and the partition members 54a and 54f correspond to the partition members 4a and 4f of the first embodiment, respectively (FIG. 3). reference). Note that the partition members 3c to 3h and the other partition members corresponding to the partition members 4c to 4e and 4h to 4j of the first embodiment are also formed by roughening the oil pan cover 2 (see FIG. 2). ).

  Between the partition members 53 a and 53 b and the partition members 54 a and 54 f and the oil pan 13, the vibration isolation member 7 is provided. The oil pan 13 and the oil pan cover 2 are coupled at a plurality of locations via the partition members 53 a and 53 b and the vibration isolation member 7. Further, the oil pan 13 and the oil pan cover 2 are coupled to each other at a plurality of locations via the partition members 54 a and 54 f and the vibration isolation member 7. The same applies to the other partition members corresponding to the partition members 3c to 3h and the partition members 4c to 4e and 4h to 4j of the first embodiment.

  In this way, by forming the partition members 53a and 53b and the partition members 54a and 54f by uneven processing, it is not necessary to add additional members, so the number of parts, the manufacturing process, and the cost can be reduced. Can do.

  In the present embodiment, the partition members 53a and 53b and the partition members 54a and 54f are formed by unevenly processing the oil pan cover 2, but may be formed by unevenly processing the oil pan 13. Good. In this case, the vibration isolating member 7 is provided between the partition members 53a and 53b and the partition members 54a and 54f and the oil pan cover 2, and the oil pan 13 and the oil pan cover 2 are separated from each other by the partition members 53a and 53b. In addition to being coupled at a plurality of locations via the vibration isolator 7, they are coupled at a plurality of locations via the partition members 54 a and 54 f and the vibration isolator 7. The same applies to other partition members.

  Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. As shown in FIG. 5 which is an AA cross section of FIG. 2, the sound insulation structure 61 of the present embodiment includes first protrusions 13 a, which are formed by partitioning members 63 a and 63 b ruggedly processing the oil pan 13. The sound insulation structure 1 of the first embodiment in that it is formed by forming an uneven portion of the oil pan cover 2 and the second convex portions 64a and 64b facing the first convex portions 13a and 13b. This is different from the sound insulation structure 51 of the second embodiment. The same applies to the other partition members corresponding to the partition members 3c to 3h of the first embodiment. The same applies to the partition members 4a and 4f and the partition members 4c to 4e and 4h to 4j provided on the side surface of the oil pan cover 2 (see FIG. 2).

  An anti-vibration member 7 is provided between the first convex portions 13a and 13b and the second convex portions 64a and 64b. The oil pan 13 and the oil pan cover 2 are separated from each other by the partition members 63a and 63b and the anti-vibration members. It is coupled at a plurality of locations via the member 7.

  As described above, the partition members 63a and 63b are formed by the first convex portions 13a and 13b formed on the oil pan 13 and the second convex portions 64a and 64b formed on the oil pan cover 2, so that separate members are formed. Therefore, it is possible to reduce the number of parts, the manufacturing process, and the cost.

  The partition members 63a and 63b are formed of first protrusions 13a and 13b provided on the oil pan 13 and a partition member separate from the oil pan cover 2 provided on the bottom surface of the oil pan cover 2. It may be.

  Other configurations are the same as those of the first embodiment and the second embodiment, and thus description thereof is omitted.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. As shown in FIG. 6, the sound insulation structure 71 of this embodiment includes an engine cover (sound insulation cover) 72 attached to the engine 112 so as to cover the lower part of the engine 112 that is a noise generation source via the air layer 21. Have. The engine cover 72 is attached to the engine 112 by an attachment portion 73.

  As shown in FIG. 7, which is an enlarged view of the main part B of FIG. 6, the attachment part 73 includes a through hole 76 drilled in the engine cover 72 and a pair of fixing members 74 a and 74 b attached to the through hole 76. And a pair of coil springs (elastic bodies) 75a and 75b which are provided between the pair of fixing members 74a and 74b and sandwich the engine cover 72. The fixing member 74a is provided with a flange portion 78a with which the coil spring 75a abuts. The fixing member 74b is provided with a flange portion 78b with which the coil spring 75b abuts. Moreover, the convex part 79a provided in the fixing member 74a is fitted in the concave part 79b provided in the fixing member 74b. Bolts 122 that are screwed into bolt holes 77 provided in the engine 112 are inserted through the pair of fixing members 74a and 74b. The pair of fixing members 74 a and 74 b are fixed to the engine 112 by the bolts 122. The fastening member fastened to the engine 112 is not limited to the bolt 122 but may be a pin, a screw, or the like.

  The engine cover 72 is not fixed to the engine 112 and is sandwiched between a pair of coil springs 75a and 75b. In this way, by attaching the engine cover 72 to the engine 112 via the pair of coil springs 75a and 75b, the radiated sound radiated from the engine cover 72 due to vibration transmission from the engine 112 to the engine cover 72 can be reduced. .

  Note that the attachment portion 73 may not include the pair of fixing members 74a and 74b. In this case, the coil spring 75a whose one end contacts the head of the bolt 122 and the other end contacts the engine cover 72, and the coil spring 75b whose one end contacts the engine cover 72 and the other end contacts the engine 112, The cover 72 is pinched.

  Further, as shown in FIG. 7 which is an enlarged perspective view of the main part B of FIG. 7 and FIG. 6, the engine cover 72 is partially bent toward the engine 112. The bent end portion 72x is in surface contact with the side surface 112b of the engine 112. It should be noted that the entire end portion 72x of the engine cover 72 may be bent and brought into surface contact with the side surface 112b of the engine 112.

  A part of the gap between the end portion 72x of the engine cover 72 and the engine 112 is covered with the end portion 72x of the engine cover 72 by bringing part of the end portion 72x of the engine cover 72 into surface contact with the engine 112. Thereby, since noise is suppressed from leaking from the gap between the end portion 72x of the engine cover 72 and the engine 112, the sound insulation performance can be improved.

  Further, as the engine 112 vibrates, a relative displacement occurs between the engine 112 and the engine cover 72, and friction occurs at the surface contact portion. Thereby, since vibration energy is converted into thermal energy and vibration is attenuated, sound insulation performance can be improved. The amount of friction generation can be controlled by increasing or decreasing the area of the end portion 72x of the engine cover 72 that is brought into contact with the side surface 112b of the engine 112.

  In addition, like the sound insulation structure 71a shown in FIG. 9 which is an enlarged view of the main part B of FIG. 6, a part or all of the end portion 72y of the engine cover 72 is bent into a C-shaped cross section so that the engine cover 72 A part or all of the end portion 72y may be in line contact with the side surface 112b of the engine 112. Even in this case, since at least a part of the gap between the end 72y of the engine cover 72 and the engine 112 is covered with the end 72y of the engine cover 72, noise is generated from the gap between the end 72y of the engine cover 72 and the engine 112. Is suppressed from leaking. In addition, friction is generated at the line contact portion due to the relative displacement between the engine 112 and the engine cover 72, so that the vibration energy is converted into heat energy and the vibration is attenuated. Thereby, re-radiation from the engine cover 72 is reduced.

  Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

(Experimental result)
The sound insulation performance was measured using the sound insulation structure 71 according to the present embodiment as an example and the sound insulation structure having a gap between the end of the engine cover 72 and the engine 112 as a comparative example. The result is shown in FIG. It can be seen that in the frequency region higher than 400 Hz, the sound insulation performance of the sound insulation structure 71 of the example is improved over the sound insulation performance of the sound insulation structure of the comparative example. This is because at least a part of the end 72x of the engine cover 72 is brought into contact with the engine 112, so that at least a part of the gap between the end 72x of the engine cover 72 and the engine 112 is covered with the end 72x of the engine cover 72. This is because noise is prevented from leaking from the gap between the end portion 72x of the engine cover 72 and the engine 112.

(Calculation result)
Next, the sound insulation structure 71 according to the present embodiment is taken as an example, and the attenuation due to friction generated between the end 72x of the engine cover 72 and the engine 112 is reduced to 1/10 of the sound insulation structure 71 of the example. The sound insulation performance was calculated using the sound insulation structure as a comparative example. The result is shown in FIG. It can be seen that the sound insulation performance of the sound insulation structure 71 of the example is improved over the sound insulation performance of the sound insulation structure of the comparative example at 1000 Hz, which is a frequency at which noise increases due to the installation of the sound insulation structure 71. This is because the relative displacement between the engine 112 and the end portion 72x of the engine cover 72 causes a vibration attenuation in the engine cover 72 due to the frictional force generated in the contact portion, and the vibration is attenuated more than in the comparative example. Because.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. As shown in FIG. 12, the sound insulation structure 81 of the present embodiment is a fourth embodiment in that it includes a metal shielding member 82 that covers a part of the gap between the end of the engine cover 72 and the engine 112. It differs from the sound insulation structure 71 of the form. The shielding member 82 may cover the entire gap between the end portion of the engine cover 72 and the engine 112.

  As shown in FIG. 13 which is an enlarged perspective view of the main part C in FIG. 12, the shielding member 82 is bent in a C-shaped cross section from one end side to the other end side, and one end portion of the shielding member 82 is a bolt. The other end of the shielding member 82 is attached to the engine 112 by a bolt 84 together with the engine cover 72. As described above, the shielding member 82 is bent in a C-shaped cross section from one end side to the other end side, whereby elasticity is imparted to the shielding member 82.

  A coil spring through which the bolt 84 is inserted may be provided between the head of the bolt 84 and the shielding member 82 or between the shielding member 82 and the engine cover 72. In this case, the elasticity of the shielding member 82 can be increased. Further, instead of the bolt 84, the engine 112, the engine cover 72, and the other end of the shielding member 82 may be coupled by the mounting portion 73 of the fourth embodiment.

  At least a part of the end portion 72 x of the engine cover 72 is in surface contact with the side surface 112 b of the engine 112. As a result, at least a part of the gap between the end portion 72x of the engine cover 72 and the engine 112 is covered with the end portion 72x of the engine cover 72, so that noise leaks from the gap between the end portion 72x of the engine cover 72 and the engine 112. Is suppressed. Further, when friction occurs at the surface contact portion, vibration energy is converted into heat energy, and vibration is attenuated.

  Further, noise leaking from a part of the gap between the end 72x of the engine cover 72 and the engine 112 is suppressed from leaking to the outside by the shielding member 82 covering the gap. Thereby, the sound insulation performance can be improved.

  Further, due to the elasticity of the shielding member 82, the shielding member 82 exhibits vibration damping properties. Therefore, the vibration energy transmitted from the engine 112 to the engine cover 72 via the shielding member 82 is converted into thermal energy, and the vibration transmitted from the engine 112 to the engine cover 72 is attenuated. Is suppressed. Thereby, the sound insulation performance can be improved.

  In addition, like the sound insulation structure 81a shown in FIG. 14 which is an enlarged view of the main part C of FIG. 12, a shielding member 82a made of a double corrugated plate having damping properties, a damping steel plate, or the like is used as the engine cover 72. You may attach along the surface of the engine cover 72 and the engine 112 so that at least one part of the clearance gap between the edge part 72x and the engine 112 may be covered. Here, at least a part of the end 72x of the engine cover 72 is in line contact with the engine 112, and the shielding member 82a and the engine cover 72 are coupled by a bolt 84 and a nut 85 screwed to the bolt 84.

  Even in this case, since at least a part of the gap between the end 72x of the engine cover 72 and the engine 112 is covered with the end 72x of the engine cover 72, noise is generated from the gap between the end 72x of the engine cover 72 and the engine 112. Is suppressed from leaking. Further, when friction occurs at the line contact portion, vibration energy is converted into heat energy, and vibration is attenuated. Further, since at least a part of the gap between the end portion 72x of the engine cover 72 and the engine 112 is covered by the shielding member 82a, noise leaking from the gap is prevented from leaking to the outside. Further, the vibration transmitted from the engine 112 to the engine cover 72 via the shielding member 82a is attenuated by the vibration damping property of the shielding member 82a, so that resonance of the engine cover 72 is suppressed.

  Other configurations are the same as those in the fourth embodiment, and thus the description thereof is omitted.

(Modification of this embodiment)
The embodiment of the present invention has been described above, but only specific examples are illustrated, and the present invention is not particularly limited, and the specific configuration and the like can be appropriately changed in design. Further, the actions and effects described in the embodiments of the invention only list the most preferable actions and effects resulting from the present invention, and the actions and effects according to the present invention are described in the embodiments of the present invention. It is not limited to what was done.

  For example, in the first to third embodiments, the oil pan cover 2 has been described as a sound insulation cover, and in the fourth and fifth embodiments, the engine cover 72 has been described as a sound insulation cover. It may cover at least part of the source.

  Moreover, in one sound insulation structure, the partition member (partition member of 1st Embodiment) separate from a noise generation source and a sound insulation cover, and the partition member (2nd Embodiment of 2nd Embodiment) which processed the sound insulation cover or the noise generation source. (Partition member) may be used in combination. Similarly, in one sound insulation structure, the partition member (partition member of the third embodiment) composed of the convex part of the sound insulation cover and the convex part of the noise generation source is replaced with another partition member (partition member of the first and second embodiments). ).

1, 51, 61, 71, 81 Sound insulation structure 2 Oil pan cover (sound insulation cover)
2a to 2i Plane 3a to 3h Partition member 4a to 4j Partition member 5a to 5aa Space 6 Granular body 7 Anti-vibration member 8 Elastic body 11 Construction vehicle 12 Engine 13 Oil pan 13a, 13b First convex part 21 Air layer 53a, 53b, 54a, 54f Partition member 63a, 63b Partition member 64a, 64b Second convex portion 72 Engine cover (sound insulation cover)
72x End portion 73 Mounting portion 74a, 74b Fixing member 75a, 75b Coil spring 82 Shield member 112 Engine 122 Bolt

Claims (9)

A sound insulation cover attached to the noise source so as to cover at least a part of the noise source via an air layer;
A partition member that partitions the air layer into a plurality of spaces;
A plurality of granules enclosed in at least one of the plurality of spaces;
Have
The sound insulation cover is configured by combining a plurality of planes.   The sound insulation structure according to claim 1, wherein the partition member is formed by unevenly processing at least one of the noise generation source and the sound insulation cover. A vibration isolating member provided between the noise generating source and the sound insulation cover together with the partition member, and having a vibration isolating property;
The sound insulation structure according to claim 1 or 2, wherein the noise generation source and the sound insulation cover are coupled at a plurality of locations via the partition member and the vibration isolation member.   The at least part of the end portion of the sound insulation cover is in contact with the noise generation source so as to cover at least a part of the gap between the end portion of the sound insulation cover and the noise generation source. The sound insulation structure of any one of 1-3.   One end is attached to the noise generation source and the other end is attached to the sound insulation cover, respectively, and further includes a shielding member that covers at least a part of a gap between the end of the sound insulation cover and the noise generation source. The sound insulation structure according to any one of claims 1 to 4.   The sound insulation structure according to claim 5, wherein the shielding member has vibration damping properties.   The sound insulation structure according to claim 1, wherein the plurality of granular materials are enclosed in the space in a state of being put in a bag.   The sound insulation structure according to claim 1, wherein the sound insulation cover is attached to the noise generation source via an elastic body.   The sound insulation structure according to claim 8, wherein the elastic body is a spring.