US3773141A - Sound-proofing wall-forming structural element - Google Patents
Sound-proofing wall-forming structural element Download PDFInfo
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- US3773141A US3773141A US00291158A US3773141DA US3773141A US 3773141 A US3773141 A US 3773141A US 00291158 A US00291158 A US 00291158A US 3773141D A US3773141D A US 3773141DA US 3773141 A US3773141 A US 3773141A
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- structural element
- wall
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- sound
- proofing
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- 230000015572 biosynthetic process Effects 0.000 claims abstract description 4
- 210000002445 nipple Anatomy 0.000 claims description 7
- 239000000463 material Substances 0.000 description 6
- 239000007787 solid Substances 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 4
- 238000005452 bending Methods 0.000 description 3
- 230000005284 excitation Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 230000003416 augmentation Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B77/00—Component parts, details or accessories, not otherwise provided for
- F02B77/11—Thermal or acoustic insulation
- F02B77/13—Acoustic insulation
Definitions
- ABSTRACT A sound-proofing structural element for the formation of a wall, in particular of a housing wall of an engine or machine, comprising a number of intersecting webs on at least one of its outer surfaces, the predetermined ratio between the wall thickness of the structural element, the dimensions of the webs and the clearances between them being such as to reduce the sound generation of the structural element.
- the invention relates to a sound-proofing wallforming structural element, particularly to a housing or part of a housing of an engine or machine.
- the frequency spectra of sound-generating processes are known either to decrease steadily as the frequency rises, a for example, the combustion chamber pressure of an internal combustion engine, or at least to decrease abruptly as in connection with mechanical thrusts, which means that the degree of sound generation diminishes either with increasing frequencies or at least as from a certain frequency level.
- Every structural element has a multitude of natural frequencies excited by means of the sound introduced into same.
- the bending frequencies of wall elements are a function of the wall thickness, of the width between supports and the properties of the material.
- the constant is av function of the type and rigidity of the supporting means. It is predetermined by the construction features and therefore, liable to be influenced to a minor degree only.
- This structural element should be particularly suitable for the manufacture of machine housings and their covers. These elements are so excited by the introduction of sound as to produce oscillation phenomena and will therefore, radiate sound transmitted by air.
- webs or the like projecting from the wall surface are arranged in spaced relation to each other in a manner known per se at least on one wall surface of the structural element, the webs extending crosswise in two directions almost perpendicular to each other, the ratio between web height plus wall thickness and wall thickness amounting at least to 4, whereas the ratio between the inside width separating adjacent webs and the width of the webs ranges from 4 to 14.
- the invention is based onthe realization that if a solid wall is resolved into a number of webs supported by means of a partition whose thickness is only a fraction of the full wall thickness, the natural frequency is at first even increased as compared with a solid wall as the distance between the webs augments, and even with very wide intervals between the webs, the natural frequency diminishes only slightly as compared with the solid wall.
- the structural element according to the invention should have no more than 2.5 times the original weight of the non-ribbed wall.
- the webs extend at least approximately in parallel relation to the outer contours of the structural element. This design offers certain advantages for reasons of solidity and because it is easily and conveniently cast.
- nipples, through bores or the like at the intersections of the webs.
- the nipples or other wall members serving for the attachment of accessories or the like to the structural element are thus increasingly reinforced.
- FIG. 1 is a cross-sectional view of a structural element according to the invention
- FIG. 2 is a top plan view of a structural element as shown in FIG. 1,
- FIG. 3 is a diagram illustrating the relationship between the relative frequency and the distance between ribs
- FIG. 4 is another diagram describing the relation-ship between the relative weight and the relative distance between ribs
- FIG. is a side elevation of the upper portion of a crankcase according to the invention.
- FIG. 6 is a front view of the crankcase shown in FIG. 5.
- FIGS. 1 and 2 illustrate the fundamental design of a sound-proofing structural element 1 according to the invention. It comprises a plate-shaped portion 2, on the outer surface 4 of which webs 3 are arranged at regular intervals and intersecting at right angles, the dimensional relationship according to the invention being such that the overall cross-sectional height h (height of web plus wall thickness s) is at least four times as large as the wall thickness s and besides, the inside width t s (distance between ribs t less web width s) is more than four times as large as the web width s.
- the graph as per FIG. 3 shows the interconnection between the relative frequencyf/f that is, the possible multiplication of the natural frequency of the structural element according to the invention as compared with the natural frequency f of a non-ribbed wall, on the one hand, and the relative rib distance (t s) ls, or the relationship between the inter-web inside width and the web width, on the other hand.
- the relation h/s that is, the relative rib height, is used as a parameter for the set of curves shown in the graph, the relation h/s 1 being applicable to a non-ribbed wall, in which case the relative frequency is l.
- the technically suitable limits for the various ratio values are highlighted in the graph by differences in shading.
- the right-hand-hatched area A is defined towards both sides of the graph by the actually feasible boundary values 4 and 14 of the relative rib distance.
- a relative web height h/s 4 represents the bottom boundary of the area A.
- the technically applicable area of the graph shown in FIG. 3 can, however, also be defined under a different angle as illustrated by the lefthand-hatched area B in FIG. 3, wherein a relative frequency 4 is assumed to be the actually suitable bottom boundary, whereas the upper boundary is defined by the straight line g representing the admissible upper boundary value for the relative weight G/G of 2.5, G signifying the weight of the ribbed wall and 6,, the weight of the non-ribbed wall.
- FIG. 4 shows the interdependence between the relative weight G/G and the relative rib distance (t-s) /s for different relative web heights h/s.
- the technically applicable boundaries of the aforesaid ratios are, as in the graph of FIG. 3, defined by the righthand-hatched area A and the lefthand-hatched area
- FIGS. 5 and 6 show a practical embodiment of the invention as applied to an internal combustion engine.
- the entire sidewall 5 and parts of the front wall 6 of the upper portion of the crankcase shown are designed as sound-proofing walls according to the invention and provided with webs 3 projecting from the outer wall surface and extending essentially in parallel relation to the outer contours of the associated wall portions.
- the webs 3 form an almost continuous orthogonal web system.
- the dimensions of, and clearances between, individual webs as well as the wall thickness relationships are determined by the ratios ac cording to the invention.
- nipples for the attachment of accessories of the internal combustion engine are provided in the web system and located at the intersections of the webs 3.
- a sound-proofing structural element for the formation of a wall particularly the wall of a housing of an engine or machine, said wall having an outer and an inner surface, a number of webs projecting from at least one of said surfaces and extending in spaced relation to each other and intersecting in two directions approximately perpendicular to each other, the ratio between the height of the webs plus the wall thickness of the structural element and the wall thickness being at least 4 and the ratio between the inside width of interweb clearances and the width of the webs being somewhere between 4 and I4.
- a structural element according to claim 1, comprising nipples on the surface supporting the said webs, the nipples being located at the intersections of the webs.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust Silencers (AREA)
Abstract
A sound-proofing structural element for the formation of a wall, in particular of a housing wall of an engine or machine, comprising a number of intersecting webs on at least one of its outer surfaces, the predetermined ratio between the wall thickness of the structural element, the dimensions of the webs and the clearances between them being such as to reduce the sound generation of the structural element.
Description
United States Patent 1 Thien et al.
[ Nov. 20, 1973 1 SOUND-PROOFING WALL-FORMING STRUCTURAL ELEMENT [76] Inventors: Gerhard Thien; Heinz Fachbach,
both of Graz, Austria [22] Filed: Sept. 22, 1972 [21] App]. No.: 291,158
[52] US. Cl. 181/33 G, 181/33 GA [51] Int. Cl. E04b [58] Field of Search 181/33 G, 33 GA,
181/33 Q, 33 K, 33 A, 33 C, 33 F, 40, 55, 71;l61/46,116,127,165,105,119,131
[56] References Cited UNITED STATES PATENTS 2,087,248 7/1937 Fischer 181/33 G 3,232,371 2/1966 Reichert et a]. 181/33 K Primary ExaminerRichard B. Wilkinson Assistant ExaminerPat Salce Att0rneyWatson, Cole, Grindle & Watson [5 7 ABSTRACT A sound-proofing structural element for the formation of a wall, in particular of a housing wall of an engine or machine, comprising a number of intersecting webs on at least one of its outer surfaces, the predetermined ratio between the wall thickness of the structural element, the dimensions of the webs and the clearances between them being such as to reduce the sound generation of the structural element.
3 Claims, 6 Drawing Figures PATENTEB W 20 925 SHEET 1C? 3 PMENIEUHBY 20 ms SHEET 2 BF 3 PIC-3.5
r W F WW/i SOUND-PROOFING WALL-FORMING STRUCTURAL ELEMENT The invention relates to a sound-proofing wallforming structural element, particularly to a housing or part of a housing of an engine or machine.
The frequency spectra of sound-generating processes are known either to decrease steadily as the frequency rises, a for example, the combustion chamber pressure of an internal combustion engine, or at least to decrease abruptly as in connection with mechanical thrusts, which means that the degree of sound generation diminishes either with increasing frequencies or at least as from a certain frequency level.
Every structural element has a multitude of natural frequencies excited by means of the sound introduced into same. By designing the structural element in such a manner as to raise the lowest natural frequencies to such a level as to reach the area of diminishing excitation one may safely anticipate a reduction of the noise produced by the structural element in question. The bending frequencies of wall elements are a function of the wall thickness, of the width between supports and the properties of the material. The basic interdependence of these values is expressed by the equation f= const. x (8/1 VT p wherein f signifies the frequency, s the wall thickness, 1 the width between supports, E the modulus of elasticity and p the density of the material. The constant is av function of the type and rigidity of the supporting means. It is predetermined by the construction features and therefore, liable to be influenced to a minor degree only.
In view of the quadratic functional relation it would be possible to decidedly influence frequency by altering the width between supports, if the latter were not to a considerable extent predetermined by the prescribed main measurements of the structural element involved. Another substantially influential value is the wall thickness. However, its increase involves a proportional, and therefore, unfeasible augmentation of weight if the same material is to be used.
In a know type of vehicle-borne diesel engine a considerable increase of the natural frequencies of wall members has been achieved by the provision of a housing featuring an extremely large wall thickness and by using a material where the relation between the modulus of elasticity and the density was particularly advantageous. The conventional cast-iron housing was replaced by one of magnesium of equal weight, that is, one having a wall thickness approximately six times larger, as a' result of which the natural frequencies of the wall portions were increased tenfold. With other portions of the engine remaining unchanged, sound attenuation thus achieved was in the order of 10 dB (A). Considerable corrosion problems and high material costs involved in this attempt at solving noise problems have so far impeded its practical application on a large scale.
It is the purpose of the present invention to provide a sound-proofing wall-forming structural element of high rigidity involving only minor additional quantities of material for the purpose of greatly reducing sound radiation. This structural element should be particularly suitable for the manufacture of machine housings and their covers. These elements are so excited by the introduction of sound as to produce oscillation phenomena and will therefore, radiate sound transmitted by air. According to the invention, webs or the like projecting from the wall surface are arranged in spaced relation to each other in a manner known per se at least on one wall surface of the structural element, the webs extending crosswise in two directions almost perpendicular to each other, the ratio between web height plus wall thickness and wall thickness amounting at least to 4, whereas the ratio between the inside width separating adjacent webs and the width of the webs ranges from 4 to 14.
The invention is based onthe realization that if a solid wall is resolved into a number of webs supported by means of a partition whose thickness is only a fraction of the full wall thickness, the natural frequency is at first even increased as compared with a solid wall as the distance between the webs augments, and even with very wide intervals between the webs, the natural frequency diminishes only slightly as compared with the solid wall.
It is therefore, possible for example, to achieve with a structural element according to the invention, having only about 25 percent of the weight of a solid wall, the same natural bending frequencies, or else to multiply the natural bending frequencies of the original wall by no more than doubling the weight of the wall through the provision of webs, depending on the distance between individual webs.
Experience has shown that if the relationship between web and wall dimensions according to the invention is strictly observed, the frequency can easily be increased at least three or four-fold in conventional types of housings and covers with ordinary excitations. With known wall elements which for reasons of solidity are provided with webs in the shape of reinforcing ribs it is normally impossible to achieve an adequate shift of natural frequency levels, adequacy being understood here to mean that resonances reach the abovementioned area of lesser excitation.
For practical purposes, the structural element according to the invention should have no more than 2.5 times the original weight of the non-ribbed wall.
According to another embodiment of the invention the webs extend at least approximately in parallel relation to the outer contours of the structural element. This design offers certain advantages for reasons of solidity and because it is easily and conveniently cast.
Finally, it is preferable according to another feature of the invention to provide nipples, through bores or the like at the intersections of the webs. The nipples or other wall members serving for the attachment of accessories or the like to the structural element are thus increasingly reinforced.
Further details of the invention will become apparent from the following description with reference to the accompanying drawings wherein FIG. 1 is a cross-sectional view of a structural element according to the invention,
FIG. 2 is a top plan view of a structural element as shown in FIG. 1,
FIG. 3 is a diagram illustrating the relationship between the relative frequency and the distance between ribs,
FIG. 4 is another diagram describing the relation-ship between the relative weight and the relative distance between ribs,
FIG. is a side elevation of the upper portion of a crankcase according to the invention, and
FIG. 6 is a front view of the crankcase shown in FIG. 5.
FIGS. 1 and 2 illustrate the fundamental design of a sound-proofing structural element 1 according to the invention. It comprises a plate-shaped portion 2, on the outer surface 4 of which webs 3 are arranged at regular intervals and intersecting at right angles, the dimensional relationship according to the invention being such that the overall cross-sectional height h (height of web plus wall thickness s) is at least four times as large as the wall thickness s and besides, the inside width t s (distance between ribs t less web width s) is more than four times as large as the web width s.
The graph as per FIG. 3 shows the interconnection between the relative frequencyf/f that is, the possible multiplication of the natural frequency of the structural element according to the invention as compared with the natural frequency f of a non-ribbed wall, on the one hand, and the relative rib distance (t s) ls, or the relationship between the inter-web inside width and the web width, on the other hand. The relation h/s, that is, the relative rib height, is used as a parameter for the set of curves shown in the graph, the relation h/s 1 being applicable to a non-ribbed wall, in which case the relative frequency is l. The technically suitable limits for the various ratio values are highlighted in the graph by differences in shading. The right-hand-hatched area A is defined towards both sides of the graph by the actually feasible boundary values 4 and 14 of the relative rib distance. A relative web height h/s 4 represents the bottom boundary of the area A. I
The technically applicable area of the graph shown in FIG. 3 can, however, also be defined under a different angle as illustrated by the lefthand-hatched area B in FIG. 3, wherein a relative frequency 4 is assumed to be the actually suitable bottom boundary, whereas the upper boundary is defined by the straight line g representing the admissible upper boundary value for the relative weight G/G of 2.5, G signifying the weight of the ribbed wall and 6,, the weight of the non-ribbed wall.
The graph of FIG. 4 shows the interdependence between the relative weight G/G and the relative rib distance (t-s) /s for different relative web heights h/s. The technically applicable boundaries of the aforesaid ratios are, as in the graph of FIG. 3, defined by the righthand-hatched area A and the lefthand-hatched area FIGS. 5 and 6 show a practical embodiment of the invention as applied to an internal combustion engine. The entire sidewall 5 and parts of the front wall 6 of the upper portion of the crankcase shown are designed as sound-proofing walls according to the invention and provided with webs 3 projecting from the outer wall surface and extending essentially in parallel relation to the outer contours of the associated wall portions. Thus with the sidewall 5 the webs 3 form an almost continuous orthogonal web system. The dimensions of, and clearances between, individual webs as well as the wall thickness relationships are determined by the ratios ac cording to the invention.
As can be seen from FIG. 5, nipples for the attachment of accessories of the internal combustion engine are provided in the web system and located at the intersections of the webs 3.
The scope of the present invention is not restricted to the embodiment hereabove described by way of example and shown in the drawings. It can also be used for the design of housing or housing members of any other type of machine whose walls are excited by sound conducted through solids, provided the proportional values according to the invention are strictly observed so as to achieve the desired sound-proofing effect.
I claim:
1. A sound-proofing structural element for the formation of a wall, particularly the wall of a housing of an engine or machine, said wall having an outer and an inner surface, a number of webs projecting from at least one of said surfaces and extending in spaced relation to each other and intersecting in two directions approximately perpendicular to each other, the ratio between the height of the webs plus the wall thickness of the structural element and the wall thickness being at least 4 and the ratio between the inside width of interweb clearances and the width of the webs being somewhere between 4 and I4.
2. A sound-proofing structural element according to claim 1, wherein said webs extend at least approximately in parallel relation to the outer contours of the structural element.
3. A structural element according to claim 1, comprising nipples on the surface supporting the said webs, the nipples being located at the intersections of the webs.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,773,141 Dated November 20, 1 973 Inventor(s) Gerhard hj en and j nz hh h It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown belowz On the title page of the patent, the following information should be added:
--[73] Assignee: Hans List, Graz, Austria Signed "and sealed this lL th day oi May 19714..
- (SEAL) Attest: I EDWARD ILFLETCHER RQ c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM poq osouo-ss I yscomM-lc'coan-ru a us, covinnnpfl' "0mm omen 5 mo own-a4.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION P t n 3.773.141 Dated November 20, 1973 Inventor(s) Gerhard Thjen and Heinz hb b It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
On the title page of the patent, the following information should be added:
--[73] Assignee: Hans List, Graz, Austria Signed and sealed this lLLth day of May 19714..
(SEAL) Attest: I
EDWARD I'LFLETCHERJR. J C. MARSHALL DANN Attesting; Officer Commissioner of Patonts FORM Po-wso (10-69)
Claims (3)
1. A sound-proofing structural element for the formation of a wall, particularly the wall of a housing of an engine or machine, said wall having an outer and an inner surface, a number of webs projecting from at least one of said surfaces and extending in spaced relation to each other and intersecting in two directions approximately perpendicular to each other, the ratio between The height of the webs plus the wall thickness of the structural element and the wall thickness being at least 4 and the ratio between the inside width of inter-web clearances and the width of the webs being somewhere between 4 and 14.
2. A sound-proofing structural element according to claim 1, wherein said webs extend at least approximately in parallel relation to the outer contours of the structural element.
3. A structural element according to claim 1, comprising nipples on the surface supporting the said webs, the nipples being located at the intersections of the webs.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US29115872A | 1972-09-22 | 1972-09-22 |
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US3773141A true US3773141A (en) | 1973-11-20 |
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US00291158A Expired - Lifetime US3773141A (en) | 1972-09-22 | 1972-09-22 | Sound-proofing wall-forming structural element |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0029898A2 (en) * | 1979-11-22 | 1981-06-10 | Messerschmitt-Bölkow-Blohm Gesellschaft mit beschränkter Haftung | Variable resonators for noise attenuation |
US4782913A (en) * | 1986-05-06 | 1988-11-08 | Dr. Alois Stankiewicz Gmbh | Constructional element with acoustic properties |
US5459291A (en) * | 1992-09-29 | 1995-10-17 | Schuller International, Inc. | Sound absorption laminate |
US20040026167A1 (en) * | 2000-07-14 | 2004-02-12 | Larsen Peter Nohr | Suction apparatus with noise reduction means |
US20060169531A1 (en) * | 2003-12-23 | 2006-08-03 | Christine Volker | Component that absorbs airborne sound |
ES2276584A1 (en) * | 2004-04-20 | 2007-06-16 | Honda Motor Co., Ltd. | Sound-proof structure in power unit |
US20100247945A1 (en) * | 2009-03-30 | 2010-09-30 | Gm Global Technology Operations, Inc. | Sheet Metal Panel Shape for Low Sound Radiation |
EP2565871A1 (en) | 2011-09-01 | 2013-03-06 | MAN Truck & Bus AG | Acoustically dampened component |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2087248A (en) * | 1932-02-15 | 1937-07-20 | Albert C Fischer | Composition sheet |
US3232371A (en) * | 1963-04-10 | 1966-02-01 | Olympia Werke Ag | Sound attenuating sheet material |
-
1972
- 1972-09-22 US US00291158A patent/US3773141A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2087248A (en) * | 1932-02-15 | 1937-07-20 | Albert C Fischer | Composition sheet |
US3232371A (en) * | 1963-04-10 | 1966-02-01 | Olympia Werke Ag | Sound attenuating sheet material |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0029898A3 (en) * | 1979-11-22 | 1981-08-26 | Messerschmitt-Bolkow-Blohm Gesellschaft Mit Beschrankter Haftung | Variable resonators for noise attenuation |
EP0029898A2 (en) * | 1979-11-22 | 1981-06-10 | Messerschmitt-Bölkow-Blohm Gesellschaft mit beschränkter Haftung | Variable resonators for noise attenuation |
US4782913A (en) * | 1986-05-06 | 1988-11-08 | Dr. Alois Stankiewicz Gmbh | Constructional element with acoustic properties |
US5459291A (en) * | 1992-09-29 | 1995-10-17 | Schuller International, Inc. | Sound absorption laminate |
US7337876B2 (en) * | 2000-07-14 | 2008-03-04 | Nilfisk-Advance A/S | Suction apparatus with noise reduction means |
US20040026167A1 (en) * | 2000-07-14 | 2004-02-12 | Larsen Peter Nohr | Suction apparatus with noise reduction means |
US20060169531A1 (en) * | 2003-12-23 | 2006-08-03 | Christine Volker | Component that absorbs airborne sound |
ES2276584A1 (en) * | 2004-04-20 | 2007-06-16 | Honda Motor Co., Ltd. | Sound-proof structure in power unit |
US20100247945A1 (en) * | 2009-03-30 | 2010-09-30 | Gm Global Technology Operations, Inc. | Sheet Metal Panel Shape for Low Sound Radiation |
EP2565871A1 (en) | 2011-09-01 | 2013-03-06 | MAN Truck & Bus AG | Acoustically dampened component |
DE102011112313A1 (en) | 2011-09-01 | 2013-03-07 | Man Truck & Bus Ag | Acoustically damped component |
CN102968984A (en) * | 2011-09-01 | 2013-03-13 | 曼卡车和巴士股份公司 | Acoustically dampened component |
US8684133B2 (en) * | 2011-09-01 | 2014-04-01 | Man Truck & Bus Ag | Acoustically damped component |
CN102968984B (en) * | 2011-09-01 | 2016-08-03 | 曼卡车和巴士股份公司 | Noise elimination component |
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