Muffler for reducing noise from cooling fans in computer systems

Abstract

A computer system comprising a chassis housing at least one heat-generating computing component, at least one heat dissipation fan housed within the chassis and configured to convectively cool the at least one heat-generating computing component, and at least one muffler positioned at the inlet or outlet of at least one heat dissipation fan. The at least one muffler comprises an inlet, an outlet, a main duct extending between the inlet and the outlet, at least one resonant chamber surrounding the main duct, and a plurality of apertures within the main duct configured to allow air and sound to flow and be transmitted between the main duct and the at least one resonant chamber.

Description

[Background technology]

[0001] With the rapid development of information technology, individuals and businesses are seeking more ways to process and store information. Computer systems (e.g., servers) as information processing systems are typically used for commercial, personal, or other purposes to process, compile, store, and / or transmit information or data. The security and reliability of such data storage and transmission are crucial. As the scale and speed of data storage and transmission continue to increase, computer systems integrate more electrical devices and components internally, consuming more power and generating more heat. Increased heat leads to higher temperatures, which affect the efficiency and reliability of computer systems. Therefore, high-speed cooling fans are typically used to lower the temperature inside computer systems.

[0002] However, high-speed cooling fans not only move more air for heat dissipation but also generate more noise within the system, which can degrade the input / output accuracy of the hard disks within the system, thereby affecting the overall reliability of the system. Furthermore, as the storage capacity and transmission speed of hard disks continue to increase, the sensitivity of hard disks to noise also increases exponentially. Therefore, reducing noise from cooling fans is crucial to ensuring the reliability of hard disk storage and transmission. Thus, a computer system is needed that provides sufficient cooling while reducing noise from cooling fans. [Overview of the project] [Means for solving the problem]

[0003] According to one embodiment, a computer system is disclosed. The computer system comprises a chassis housing at least one heat-generating computing component, at least one heat dissipation fan housed within the chassis and configured to convectively cool the at least one heat-generating computing component, and at least one muffler positioned at the inlet or outlet of the at least one heat dissipation fan. The at least one muffler comprises an inlet, an outlet, a main duct extending between the inlet and the outlet, at least one resonant chamber surrounding the main duct, and a plurality of apertures within the main duct configured to allow air to flow between the main duct and the at least one resonant chamber.

[0004] According to another embodiment, a process for reducing noise from a cooling fan in a computer system is disclosed. This process includes obtaining a target value for noise reduction within at least one frequency band, determining the maximum cross-sectional area and maximum length of a muffler, designing a muffler based on the target value for noise reduction, as well as the maximum cross-sectional area and maximum length, and positioning the muffler at the inlet or outlet of the cooling fan. The muffler comprises an inlet, an outlet, a main duct extending between the inlet and the outlet, at least one resonant chamber surrounding the main duct, and a plurality of apertures within the main duct configured to allow air to flow between the main duct and the at least one resonant chamber.

[0005] Other features and aspects of the present invention will be described in further detail below.

[0006] A complete and effective disclosure of this invention, including the best mode for those skilled in the art, is described more specifically in the remainder of this specification, including references to the accompanying drawings. [Brief explanation of the drawing]

[0007] [Figure 1] A cross-sectional view of the muffler according to this disclosure is shown. [Figure 2]Shows a perspective view of a muffler according to the present disclosure. [Figure 3] Shows a perspective view of an integrally attached set of mufflers according to the present disclosure. [Figure 4] Shows a computer server system. [Figure 5] Shows a computer system including a set of mufflers according to the present disclosure. [Figure 6] Shows an exemplary target sound transmission loss curve. [Figure 7] Is a diagram showing the maximum length and cross-sectional area for muffler design. [Figure 8] Is an acceleration curve obtained from a cantilever vibration test of two polymer compositions.

Mode for Carrying Out the Invention

[0008] It should be understood by those skilled in the art that this discussion is only an explanation of exemplary embodiments and is not intended to limit the broader aspects of the present invention.

[0009] Generally, the present invention is directed to a computer system that houses a muffler for reducing noise generated by a radiator fan. The computer system (e.g., a server) includes a chassis (e.g., a server rack) that houses computing components that generate heat. As part of a cooling system for the computing components, at least one radiator fan is also housed within the chassis. The radiator fan can blow air in the direction of the computing components or blow air away from the computing components, thereby exhausting the heated air. In either configuration, a muffler is positioned inside the chassis to reduce the noise level (i.e., sound pressure) in the computing components that can house a noise-sensitive hard disk drive (HDD). By reducing the noise in the HDD, the HDD can operate faster and more accurately, and as a result, the computer system becomes faster and more accurate.

[0010] Advantageously, the muffler can be customized for each particular computer system. For example, its shape can be designed to fit within a particular chassis so as to avoid interference with any computing components or any other structures. In addition, the internal structure of the muffler can be adjusted to provide a particular sound transmission loss within a given frequency band. Thus, the muffler can be designed to suit the particular needs of a particular computer system.

[0011] By using such a muffler, the performance of the HDD within the system can be dramatically improved. For example, the input / output operations per second (IOPS) of the HDD can be increased by about 10% or more in some embodiments, about 30% or more in some embodiments, about 50% or more in some embodiments, and about 70% to about 100% in some embodiments as compared to the same system without the muffler.

[0012] The muffler can reduce the sound pressure within the chassis at frequencies from 1,500 to 10,000 Hz by at least about 10 dB in some embodiments, about 15 dB in some embodiments, and about 20 dB in some embodiments.

[0013] The muffler can be made from a variety of different materials including metals and polymers. In some preferred embodiments, the muffler includes a polymer composition containing a polymer matrix. Any of a variety of polymers or combinations of polymers can generally be used in the polymer matrix. For example, the polymer can have semi-crystalline or crystalline properties. In one embodiment, the polymer can be semi-crystalline. In another embodiment, the polymer can be crystalline. In addition, in one embodiment, the polymer can be an aromatic polymer. Instead, in another embodiment, the polymer can be an aliphatic polymer.

[0014] Suitable polymers may include thermoplastic polymers. For example, these polymers may include polyolefins (e.g., ethylene polymers, propylene polymers, etc.), polyamides (e.g., aliphatic, semi-aromatic, or aromatic polyamides), polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, liquid crystal polymers), polyarylene sulfides, polyetherimides, polyacetals (e.g., polyoxymethylene), polyphenylene oxides, polyaryl ketones (e.g., polyetheretherketones, polyetherketoneketones, etc.), polycarbonates, and blends thereof.

[0015] In any case, polymers can generally be considered “high-performance” polymers because they have relatively high glass transition temperatures and / or high melting temperatures. Thus, such high-performance polymers can provide a considerable degree of heat resistance to polymer compositions. For example, polymers may have glass transition temperatures of about 30°C or higher, about 40°C or higher in some embodiments, about 50°C to about 250°C in some embodiments, and about 60°C to about 150°C in some embodiments. In some embodiments, polymers may also have melting temperatures of about 180°C or higher, about 200°C or higher in some embodiments, about 210°C to about 400°C in some embodiments, and about 220°C to about 380°C in some embodiments. The glass transition and melting temperatures can be determined using differential scanning calorimetry ("DSC") as determined by ISO tests No. 11357-2:2013 (glass transition) and 11357-3:2011 (melting), as is well known in the art.

[0016] A suitable example of a semicrystalline polymer may be a polyamide. For example, in one embodiment, the polyamide may be an aromatic polyamide. In this regard, aromatic polyamides may have relatively high melting temperatures, such as about 200°C or higher, about 220°C or higher in some embodiments, and about 240°C to about 320°C in some embodiments, as determined using differential scanning calorimetry according to ISO test No. 11357. The glass transition temperature of aromatic polyamides is similarly generally about 110°C to about 160°C. In another embodiment, the polyamide may be an aliphatic polyamide. In this regard, aliphatic polyamides may also have relatively high melting temperatures, such as about 180°C or higher, about 200°C or higher in some embodiments, and about 210°C to about 320°C in some embodiments, as determined using differential scanning calorimetry according to ISO test No. 11357. The glass transition temperature of aliphatic polyamides is similarly generally about 30°C to about 170°C.

[0017] Aromatic polyamides typically contain repeating units synthesized by polycondensation of dicarboxylic acids (e.g., aromatic dicarboxylic acids) and diamines (e.g., aliphatic diamines), which are jointly linked by amide bonds (NH-CO). For example, aromatic polyamides may contain aromatic repeating units derived from aromatic dicarboxylic acids, such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and combinations thereof. Terephthalic acid is particularly preferred. It should be understood that, of course, other types of acid units, such as aliphatic dicarboxylic acid units and polyfunctional carboxylic acid units, may also be used.

[0018] Aliphatic polyamides typically also contain repeating units linked together by amide bonds (NH-CO). These polyamides can be synthesized by various techniques. For example, polyamides can be formed by ring-opening polymerization, such as the ring-opening polymerization of caprolactams. These polyamides can also be synthesized by polycondensation of dicarboxylic acids (e.g., aliphatic dicarboxylic acids), diamines, etc. For example, aromatic polyamides may contain aliphatic repeating units derived from aliphatic dicarboxylic acids, such as adipic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, brassic acid, tetradecanediic acid, pentadecanediic acid, hexadecanedioic acid, octadecanediic acid, dimeric acids, cis- and / or trans-cyclohexane-1,4-dicarboxylic acid, cis- and / or trans-cyclohexane-1,3-dicarboxylic acid, and combinations thereof. Adipic acid is particularly preferred.

[0019] Polyamides may also contain aliphatic repeating units derived from aliphatic diamines, typically having 4 to 14 carbon atoms. Examples of such diamines include linear aliphatic alkylenediamines, e.g., 1,4-tetramethylenediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine; branched aliphatic alkylenediamines, e.g., 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 2-methyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, and combinations thereof. Repeating units derived from 1,9-nonanediamine and / or 2-methyl-1,8-octanediamine are particularly preferred. Naturally, other diamine units, such as alicyclic diamines and aromatic diamines, can also be used.

[0020] Particularly preferred aromatic polyamides are poly(nonamethylene terephthalamide) (PA9T), poly(nonamethylene terephthalamide / nonamethylene decanediamide) (PA9T / 910), poly(nonamethylene terephthalamide / nonamethylene dodecanediamide) (PA9T / 912), poly(nonamethylene terephthalamide / 11-aminodondecaneamide) (PA9T / 11), poly(nonamethylene terephthalamide / 12-aminodondecaneamide) (PA9T / 12), poly(nonamethylene terephthalamide / 11-aminodondecaneamide) (PA10T / 11), poly(nonamethylene terephthalamide / 12-aminodondecaneamide) (PA10T / 12), and poly(decamethylene terephthalamide / decamethylene decanediamide) Poly(Decamethylene Terephthalamide / Decamethylene Dodecanediamide)(PA10T / 1010), Poly(Decamethylene Terephthalamide / Tetramethylene Hexanediamide)(PA10T / 46), Poly(Decamethylene Terephthalamide / Caprolactam)(PA10T / 6), Poly(Decamethylene Terephthalamide / Hexamethylene Hexanediamide) This may include poly(sandiamide) (PA10T / 66), poly(dodecamethylene terephthalamide / dodecamethylene didodecanediamide) (PA12T / 1212), poly(dodecamethylene terephthalamide / caprolactam) (PA12T / 6), poly(dodecamethylene terephthalamide / hexamethylene hexanediamide) (PA12T / 66), polyphthalamide (PPA), etc. Particularly preferred aliphatic polyamides include: Examples include polyamide 4,6, polyamide 5,10, polyamide 6, polyamide 6,6, polyamide 6,9, polyamide 6,10, polyamide 6,12, polyamide 11, and polyamide 12. Further examples of suitable aromatic polyamides are described in U.S. Patent No. 8,324,307 by Harder et al.

[0021] Another suitable semi-crystalline aromatic polymer is an aromatic polyester which is a condensation product of an aromatic dicarboxylic acid having 8 to 14 carbon atoms and at least one diol. Suitable diols include, for example, neopentyl glycol, cyclohexanedimethanol, 2,2-dimethyl-1,3-propanediol, and aliphatic glycols of the chemical formula HO(CH2) n OH (where n is an integer from 2 to 10). Suitable aromatic dicarboxylic acids include, for example, isophthalic acid, terephthalic acid, 1,2-di(p-carboxyphenyl)ethane, 4,4'-dicarboxydiphenyl ether, etc., as well as combinations thereof. The condensed ring may also be present in, for example, 1,4- or 1,5-, or 2,6-naphthalene-dicarboxylic acid. Specific examples of such aromatic polyesters include, for example, poly(ethylene terephthalate) (PET), poly(1,4-butylene terephthalate) (PBT), poly(1,3-propylene terephthalate) (PPT), poly(1,4-butylene 2,6-naphthalate) (PBN), poly(ethylene 2,6-naphthalate) (PEN), poly(1,4-cyclohexylene dimethylene terephthalate) (PCT), as well as copolymers and mixtures of the foregoing.

[0022] Polyarylene sulfide is also a suitable semi-crystalline aromatic polymer. The polyarylene sulfide used in the composition generally has the following chemical formula: -[(Ar 1 ) n -X] m -[(Ar 2 ) i -Y] j -[(Ar 3 ) k -Z] l -[(Ar 4 ) o -W] p - and has repeating units of the formula, where Ar 1 , Ar 2 , Ar 3 and Ar 4These are independently arylene units consisting of 6 to 18 carbon atoms; W, X, Y, and Z are independent of each other. A divalent linking group selected from -SO2-, -S-, -SO-, -CO-, -O-, -C(O)O-, or an alkylene or alkylidene group of 1 to 6 carbon atoms, wherein at least one of the linking groups is -S-; n, m, i, j, k, l, o, and p are independently 0, 1, 2, 3, or 4, provided that their sum is 2 or greater.

[0023] Arylene unit: Ar 1 Ar 2 Ar 3 , and Ar 4 The units may be selectively substituted or unsubstituted. Favorable arylene units are phenylene, biphenylene, naphthalene, anthracene, and phenanthrene. Polyarylene sulfides typically contain more than about 30 mol%, more than about 50 mol%, or more than about 70 mol% of arylene sulfide (-S-) units. For example, a polyarylene sulfide may contain at least 85 mol% of sulfide bonds directly bonded to two aromatic rings. In a particular embodiment, the polyarylene sulfide may contain, as a component, a phenylene sulfide structure -(C6H4-S) n -A polyphenylene sulfide as defined herein, containing (where n is an integer greater than or equal to 1).

[0024] Synthetic techniques that can be used to produce polyarylene sulfides are generally known in the art. For example, a process for producing polyarylene sulfides may involve reacting a material that supplies hydrosulfide ions (e.g., alkali metal sulfides) with a dihalo-aromatic compound in an organic amide solvent. Alkali metal sulfides may be, for example, lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, or mixtures thereof. If the alkali metal sulfide is a hydrate or aqueous mixture, it can be treated by dehydration prior to the polymerization reaction. Alkali metal sulfides can also be produced in situ. In addition, small amounts of alkali metal hydroxides may be included in the reaction to remove or react with alkali metal sulfides to remove impurities such as alkali metal polysulfides or alkali metal thiosulfates, which may be present in very small amounts (e.g., to convert such impurities into harmless materials).

[0025] Dihalo-aromatic compounds may include, but are not limited to, o-dihalobenzene, m-dihalobenzene, p-dihalobenzene, dihalotoluene, dihalonaphthalene, methoxy-dihalobenzene, dihalobiphenyl, dihalobenzoic acid, dihalodiphenyl ether, dihalodiphenyl sulfone, dihalodiphenyl sulfoxide, or dihalodiphenyl ketone. Dihalo-aromatic compounds may be used alone or in any combination thereof. Specific exemplary dihaloaromatic compounds include, but are not limited to, p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene, 2,5-dichlorotoluene, 1,4-dibromobenzene, 1,4-dichloronaphthalene, 1-methoxy-2,5-dichlorobenzene, 4,4'-dichlorobiphenyl, 3,5-dichlorobenzoic acid, 4,4'-dichlorodiphenyl ether, 4,4'-dichlorodiphenyl sulfone, 4,4'-dichlorodiphenyl sulfoxide, and 4,4'-dichlorodiphenyl ketone. The halogen atoms may be fluorine, chlorine, bromine, or iodine, and two halogen atoms in the same dihaloaromatic compound may be the same or different from each other. In one embodiment, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, or a mixture of two or more of these compounds is used as the dihaloaromatic compound. As is well known in the art, monohalo compounds (not necessarily aromatic compounds) can also be used in combination with dihaloaromatic compounds to form terminal groups of polyarylene sulfide or to adjust the polymerization reaction and / or molecular weight of polyarylene sulfide.

[0026] Polyarylene sulfides can be homopolymers or copolymers. For example, selective combinations of dihaloaromatic compounds can result in polyarylene sulfide copolymers containing two or more different units. For example, when p-dichlorobenzene is used in combination with m-dichlorobenzene or 4,4'-dichlorodiphenylsulfone, the chemical formula is: [ka] A segment having the structure, and chemical formula: [ka] A segment having the structure, or chemical formula: [ka] A polyarylene sulfide containing a segment having the structure can be formed.

[0027] Polyarylene sulfides can be linear, semi-linear, branched, or crosslinked. Linear polyarylene sulfides typically contain 80 mol% or more of repeating units -(Ar-S)-. Such linear polymers may also contain small amounts of branched or crosslinked units, but the amount of branched or crosslinked units is typically less than about 1 mol% of the total monomer units of the polyarylene sulfide. Linear polyarylene sulfide polymers can be random copolymers or block copolymers containing the repeating units described above. Semi-linear polyarylene sulfides can similarly have crosslinked or branched structures in which small amounts of one or more monomers having three or more reactive functional groups are introduced into the polymer. As an example, the monomer component used to form a semi-linear polyarylene sulfide may contain a certain amount of a polyhalo-aromatic compound having two or more halogen substituents per molecule, which can be used in the preparation of branched polymers. Such monomers have the chemical formula R'X nIt can be expressed as follows, where each X is selected from chlorine, bromine, and iodine, n is an integer from 3 to 6, and R' is a polyvalent aromatic radical of valency n that can have up to about 4 methyl substituents, and the total number of carbon atoms in R' is in the range of 6 to about 16. Examples of several polyhalo-aromatic compounds substituted with two or more halogens per molecule that can be used to form semilinear polyarylene sulfides include 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3-dichloro-5-bromobenzene, 1,2,4-triiodobenzene, 1,2,3,5-tetrabromobenzene, hexachlorobenzene, 1,3,5-trichloro-2,4,6-trimethylbenzene, 2,2',4,4'-tetrachlorobiphenyl, 2,2',5,5'-tetraiodobiphenyl, 2,2',6,6'-tetrabromo-3,3',5,5'-tetramethylbiphenyl, 1,2,3,4-tetrachloronaphthalene, 1,2,4-tribromo-6-methylnaphthalene, and mixtures thereof.

[0028] Another suitable semicrystalline aromatic polymer that can be used in the present invention is polyaryletherketone. Polyaryletherketones are semicrystalline polymers having relatively high melting temperatures, such as about 300°C to about 400°C, about 310°C to about 390°C in some embodiments, and about 330°C to about 380°C in some embodiments. The glass transition temperature can similarly be about 110°C to about 200°C. Particularly preferred polyaryletherketones are those that mainly consist of a phenyl moiety along with ketone and / or ether moieties. Examples of such polymers include polyetheretherketone ("PEEK"), polyetherketone ("PEK"), polyetherketoneketone ("PEKK"), polyetherketoneetherketoneketone ("PEKEKK"), polyetheretherketoneketone ("PEEKK"), polyether-diphenyl-ether-ether-diphenyl-ether-phenyl-ketone-phenyl, and blends and copolymers thereof.

[0029] In addition to the polymers mentioned above, crystalline polymers can also be used in polymer compositions. Particularly preferred are liquid crystalline polymers, which have a high degree of crystallinity that allows for effective filling of small spaces in molds. Liquid crystalline polymers are generally classified as "thermotropic" insofar as they have a rod-like structure and can exhibit crystalline behavior in their molten state (e.g., thermotropic nematic state). These polymers may also be commonly called polyesters. The polymers have relatively high melting temperatures, such as about 250°C to about 400°C, about 280°C to about 390°C in some embodiments, and about 300°C to about 380°C in some embodiments. Such polymers can be formed from one or more types of repeating units known in the art. Liquid crystalline polymers may typically contain one or more aromatic ester repeating units in amounts of about 60 mol% to about 99.9 mol%, about 70 mol% to about 99.5 mol%, and about 80 mol% to about 99 mol% of the polymer. The repeating unit of an aromatic ester is generally represented by the following chemical formula (I): [ka] It can be expressed by, in the formula, Ring B is a substituted or unsubstituted 6-membered aryl group (e.g., 1,4-phenylene or 1,3-phenylene), a substituted or unsubstituted 6-membered aryl group condensed to a substituted or unsubstituted 5-membered or 6-membered aryl group (e.g., 2,6-naphthalene), or a substituted or unsubstituted 6-membered aryl group linked to a substituted or unsubstituted 5-membered or 6-membered aryl group (e.g., 4,4-biphenylene). Y1 and Y2 are independently O, C(O), NH, C(O)HN, or NHC(O).

[0030] Typically, at least one of Y1 and Y2 is C(O). Examples of such aromatic ester repeating units may include, for example, aromatic dicarbon repeating units (where Y1 and Y2 in chemical formula I are C(O)), aromatic hydroxycarboxylic acid repeating units (where Y1 is O and Y2 is C(O) in chemical formula I), and various combinations thereof.

[0031] For example, aromatic repeating units derived from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, bis(4-carboxyphenyl) ether, bis(4-carboxyphenyl)butane, bis(4-carboxyphenyl)ethane, bis(3-carboxyphenyl) ether, bis(3-carboxyphenyl)ethane, and their alkyl, alkoxy, aryl, and halogen substituents, as well as combinations thereof, may be used. Particularly preferred aromatic dicarboxylic acids may include, for example, terephthalic acid ("TA"), isophthalic acid ("IA"), and 2,6-naphthalenedicarboxylic acid ("NDA"). When used, repeating units derived from aromatic dicarboxylic acids (e.g., IA, TA, and / or NDA) each typically constitute about 1 mol% to about 40 mol%, about 2 mol% to about 30 mol%, and about 5 mol% to about 25% of the polymer.

[0032] Aromatic hydroxycarbone repeating units derived from aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 4-hydroxy-4'-biphenylcarboxylic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-5-naphthoic acid, 3-hydroxy-2-naphthoic acid, 2-hydroxy-3-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid, and their alkyl, alkoxy, aryl, and halogen substituents, as well as combinations thereof, may also be used. Particularly preferred aromatic hydroxycarboxylic acids are 4-hydroxybenzoic acid ("HBA") and 6-hydroxy-2-naphthoic acid ("HNA"). When used, repeating units derived from hydroxycarboxylic acids (e.g., HBA and / or HNA) typically constitute about 20 mol% or more of the polymer, about 25 mol% or more in some embodiments, about 30 mol% or more in some embodiments, about 40 mol% or more in some embodiments, about 50 mol% or more in some embodiments, about 55 mol% to 100 mol% in some embodiments, and about 60 mol% to 95 mol% in some embodiments.

[0033] Other repeating units may also be used in polymers. In certain embodiments, repeating units derived from aromatic diols may be used, such as hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl (or 4,4'-biphenol), 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl ether, bis(4-hydroxyphenyl)ethane, and their alkyl, alkoxy, aryl, and halogen substituents, as well as combinations thereof. Particularly preferred aromatic diols may include, for example, hydroquinone ("HQ") and 4,4'-biphenol ("BP"). When used, repeating units derived from aromatic diols (e.g., HQ and / or BP) typically constitute about 1 mol% to about 50 mol%, about 1 to about 40 mol%, about 2 mol% to about 40 mol%, about 5 mol% to about 35 mol%, and about 5 mol% to about 25% of the polymer. Repeating units derived from aromatic amides (e.g., acetaminophen ("APAP")) and / or aromatic amines (e.g., 4-aminophenol ("AP"), 3-aminophenol, 1,4-phenylenediamine, 1,3-phenylenediamine, etc.) may also be used. When used, repeating units derived from aromatic amides (e.g., APAP) and / or aromatic amines (e.g., AP) typically constitute about 0.1 mol% to about 20 mol%, about 0.5 mol% to about 15 mol%, and about 1 mol% to about 10 mol% of the polymer. It should also be understood that various other monomer repeating units can be incorporated into the polymer. For example, in certain embodiments, the polymer may contain one or more repeating units derived from non-aromatic monomers such as aliphatic or alicyclic hydroxycarboxylic acids, dicarboxylic acids, diols, amides, and amines. Naturally, in other embodiments, the polymer may be "fully aromatic" in that it lacks repeating units derived from non-aromatic (e.g., aliphatic or alicyclic) monomers.

[0034] In some preferred embodiments, the polymer composition contains an aliphatic polyamide such as polyamide 6 and / or polyamide 6,6. When the presence of polyamide 6 is less than 40% by weight based on the total weight of polyamide 6,6 and polyamide 6, polyamides based on a blend of polyamide 6,6 and polyamide 6 may be particularly useful. Among these polyamide resins, those having a number average molecular weight of about 7,000 to 30,000 are preferably used.

[0035] The polymer in the polymer matrix may be present in an amount of about 30% by weight or more, about 40% by weight or more in some embodiments, about 40% by weight to about 99.5% by weight in some embodiments, about 50% by weight to about 95% by weight in some embodiments, about 60% by weight to about 90% by weight in some embodiments, and about 60% by weight to about 85% by weight in some embodiments.

[0036] In some embodiments, fiber reinforcing agents are included in the polymer composition to improve mechanical strength, such as tensile strength and flexural strength, and to suppress shrinkage of the muffler.

[0037] Examples of fiber reinforcing agents include inorganic fibers such as glass fibers, carbon fibers, graphite fibers, silica-alumina fibers, zirconia fibers, and ceramic fibers; metallic fibers such as stainless steel, aluminum, titanium, copper, or brass fibers; and organic fibers such as para-aramid fibers, meta-aramid fibers, fluoropolymer fibers, or liquid crystal aromatic fibers. Such fibers can be used individually or in combination with each other. From the viewpoint of reinforcing effect, the fiber reinforcing agent is preferably glass fiber, carbon fiber, or para-aramid fiber. Considering availability and cost, glass fiber is preferred.

[0038] Among glass fibers, chopped strands produced from E-glass (alkali-free glass) are preferred. The average fiber diameter of the fiber reinforcing agent is not particularly limited. For example, in some embodiments it is in the range of 1 to 100 μm, in some embodiments it is in the range of about 3 to 30 μm, and in some embodiments it is in the range of about 5 to 15 μm. The average fiber length of the fiber reinforcing agent is also not particularly limited and can be in the range of about 2 to 4 mm before mixing, for example.

[0039] In addition, fiber reinforcing agents may be surface-treated as needed, via the use of surface treatment agents (e.g., epoxy compounds, acrylic compounds, isocyanate compounds, silane compounds, or titanate compounds). Glass fibers, especially when used in a polyamide resin matrix, are preferably surface-treated with silane compounds (also known as silane coupling agents).

[0040] When used, the amount of fiber reinforcing agent in the composition may be in the range of about 5 to 45% by weight, about 20 to 40% by weight in some embodiments, and about 25 to 35% by weight in some embodiments, based on the total weight of the polymer composition.

[0041] When a fiber reinforcing agent is present, the weight ratio between the polymer resin and the fiber reinforcing agent is in the range of approximately 50:50 to 95:5, approximately 55:45 to 85:15 in some embodiments, approximately 60:40 to 80:20 in some embodiments, and approximately 65:35 to 75:25 in some embodiments.

[0042] The polymer composition may further contain certain particulate fillers. Examples of particulate fillers include, for example, boron-containing compounds (e.g., boron nitride, sodium tetraborate, potassium tetraborate, calcium tetraborate, etc.), alkaline earth metal carbonates (e.g., calcium magnesium carbonate), oxides (e.g., titanium dioxide, aluminum oxide, magnesium oxide, zinc oxide, antimony trioxide, etc.), silicates (e.g., talc, sodium aluminum silicate, calcium silicate, magnesium silicate, etc.), and alkaline earth metal salts (e.g., calcium carbonate, calcium sulfate, etc.). For example, the inventors have discovered that by adding ZnO to the polymer matrix in the presence of a fiber reinforcing agent, a composition with improved vibration damping and noise reduction properties can be provided.

[0043] While we do not wish to be bound by theory, it is hypothesized that the damping effect of zinc oxide may be due to its piezoelectric properties.

[0044] Preferably, when used, the zinc oxide is needle-shaped, dendritic, or wire-shaped crystalline zinc oxide. In some embodiments, the zinc oxide is nano-zinc oxide (N-ZnO) or zinc oxide whiskers, such as tetrapod-shaped zinc oxide whiskers (T-ZnOw). The nanoparticles are particles having an average particle size of 5 to 100 nm, produced by a suitable production process.

[0045] Zinc oxide whiskers (e.g., T-ZnOw) have a quadrupedal shape in microscopic images and a porous appearance in bulk. Under a microscope, zinc oxide crystals have four needle-like crystals extending from the center. The length of each needle (or whisker), measured from the base in contact with the center to the tip, exceeds 3 micrometers. T-ZnOw whiskers are known to be flexible, have a high modulus of elasticity, and possess a very high specific gravity of approximately 5.8. Due to its unique shape, including high strength and high elasticity, T-ZnOw has advantageous properties compared to other crystalline forms of zinc oxide.

[0046] Zinc oxide may be surface-treated as needed, via the use of surface treatment agents as described above. Nano-zinc oxide is preferably surface-treated with a silane compound (also known as a silane coupling agent) to provide good dispersion of nanoparticles in the polymer matrix. Zinc oxide whiskers are less prone to particulate aggregation and are preferably not surface-treated with a silane coupling agent.

[0047] In one embodiment, the polymer composition contains nano-zinc oxide having a particle size in the range of about 10 to 60 nm.

[0048] In another embodiment, the composition contains zinc oxide whiskers in the micrometer range. In one embodiment, the zinc oxide is tetrapodized zinc oxide whiskers that are not surface-treated with a silane coupling agent.

[0049] In some embodiments, the particulate filler may include clay minerals. Examples of such clay minerals include, for example, talc(Mg)3Si4O 10 (OH)2)haloysite(Al)2Si2O5(OH)4)kaolinite(Al)2Si2O5(OH)4)illite((K,H)3O)(Al,Mg,Fe)2(Si,Al)4O 10 [(OH)2,(H2O)])Montmorillonite (Na,Ca) 0.33 (Al,Mg)2Si4O 10 (OH)2nH2O), vermiculite ((MgFe,Al)3(Al,Si)4O 10 (OH)24H2O), palygorskite ((Mg,Al)2Si4O 10 (OH)·4(H2O)), pyrophyllite (Al))2Si4O 10 Examples include (OH)2) and combinations thereof. Other suitable silicate fillers may also be used, such as calcium silicate, aluminum silicate, mica, diatomaceous earth, and wollastonite. For example, mica may be a particularly suitable mineral for use in the present invention. As used herein, the term "mica" generally refers to muscovite (KAl)2(AlSi3)O 10(OH)2), biotite (K(Mg,Fe)3(AlSi3)O 10 (OH)2), Phlogopite (KMg)3(AlSi3)O 10 (OH)2), red mica (K(Li,Al) 2-3 (AlSi3)O 10 (OH)2), glauconite (K,Na)(Al,Mg,Fe)2(Si,Al)4O 10 This means including any of these materials, such as (OH)2) and combinations thereof.

[0050] When used, the amount of particulate filler used in the composition may be in the range of about 1 to 25% by weight, and in some embodiments about 5 to 10% by weight, based on the total weight of the polymer composition.

[0051] A wide variety of additional additives may also be included in the polyamide composition, such as impact modifiers, compatibilizers, particulate fillers (e.g., mineral fillers), lubricants, pigments, antioxidants, light stabilizers, heat stabilizers, and / or other materials added to improve properties and processability. In some embodiments, the composition does not contain flame retardants.

[0052] The polymer matrix and other optional additives may be melted or blended together. The components may be supplied to an extruder separately or together, and the extruder may include at least one screw rotatably mounted and housed in a barrel (e.g., a cylindrical barrel), which may define a supply section and a melting section located downstream from the supply section along the length of the screw. The extruder may be a single-screw or twin-screw extruder. The screw speed may be selected to achieve a desired residence time, shear rate, melting temperature, etc. For example, the screw speed may be in the range of about 50 to about 800 revolutions per minute ("rpm"), about 70 to about 150 rpm in some embodiments, and about 80 to about 120 rpm in some embodiments. The apparent shear rate during melting may also be in the range of about 100 to about 10,000 per second, about 500 to about 5,000 per second in some embodiments, and about 800 to about 1,200 per second in some embodiments. The apparent shear rate is equal to 4Q / R3, where Q is the volumetric flow rate of the polymer molten material ("m3 / s") and R is the radius ("m") of the capillary (e.g., the die of an extruder) through which the molten polymer flows.

[0053] Regardless of how the components are incorporated into the composition, the resulting melt viscosity is generally low enough to flow easily into the cavity of a mold to form a small circuit board. For example, in a particular embodiment, the polymer composition may have a melt viscosity of about 5 Pa·s or more, in some embodiments about 30 Pa·s or more, in some embodiments about 80 Pa·s to about 1000 Pa·s, in some embodiments about 100 Pa·s to about 700 Pa·s, in some embodiments about 200 Pa·s to about 600 Pa·s, and in some embodiments about 250 Pa·s to about 500 Pa·s, determined at a shear rate of 1,000 per second.

[0054] The inventors have discovered that the noise reduction capability of a muffler is improved when it is formed from a specific polymer composition. For example, noise reduction is improved when the muffler is formed from a polymer composition having a high tandelta, such as about 0.1 or higher, about 0.12 or higher in some embodiments, about 0.15 or higher in some embodiments, about 0.18 or higher in some embodiments, and about 0.2 or higher in some embodiments, as measured at 60°C using dynamic mechanical analysis.

[0055] The polymer composition may also have excellent thermal and mechanical properties and processability. For example, the melting temperature of the polymer composition may be, for example, about 200°C to about 400°C, about 220°C to about 380°C in some embodiments, about 250°C to about 360°C in some embodiments, and about 260°C to about 350°C in some embodiments. The temperature of deflection under load ("DTUL"), a measure of short-term heat resistance, may be about 50°C or higher, about 60°C to about 350°C in some embodiments, about 70°C to about 320°C in some embodiments, and about 75°C to about 290°C in some embodiments.

[0056] Polymer compositions may also possess excellent mechanical properties. For example, a polymer composition may exhibit a tensile strength of about 10 MPa or more, about 50 MPa or more in some embodiments, about 100 MPa to about 300 MPa in some embodiments, about 150 MPa to about 275 MPa in some embodiments, and about 200 MPa to about 250 MPa in some embodiments. A polymer composition may exhibit a tensile elongation at break of about 1% or more, about 2% or more in some embodiments, about 3% to about 30% in some embodiments, and about 5% to about 25% in some embodiments. A polymer composition may exhibit a tensile modulus of elasticity of about 1,000 MPa or more, about 5,000 MPa or more in some embodiments, about 7,000 MPa to about 25,000 MPa in some embodiments, and about 11,000 MPa to about 20,000 MPa in some embodiments. Tensile properties can be determined at a temperature of 23°C according to ISO Test No. 527:2019. Furthermore, the polymer composition may exhibit a flexural strength of approximately 20 MPa or more, approximately 100 MPa or more in some embodiments, approximately 150 MPa or more in some embodiments, approximately 190 MPa to approximately 500 MPa in some embodiments, and approximately 220 MPa to approximately 300 MPa in some embodiments. The polymer composition may exhibit a flexural modulus of approximately 1,000 MPa or more, approximately 5,000 MPa or more in some embodiments, approximately 8,000 MPa to approximately 25,000 MPa in some embodiments, and approximately 10,000 MPa to approximately 20,000 MPa in some embodiments. The flexural properties can be determined at a temperature of 23°C according to 178:2010. In addition, the polymer composition may also have high impact strength, which may be useful when forming thin substrates. The polymer composition may, for example, have an impact strength of approximately 2 kJ / m 2 In some embodiments described above, the load is approximately 10 kJ / m³. 2 In some embodiments described above, the load is approximately 15 to 30 kJ / m³. 2 In some embodiments, the load is approximately 18 kJ / m³. 2 ~about 25kJ / m 2 It may have an impact strength with a Charpy notch. The impact strength can be determined at a temperature of 23°C according to ISO test No. ISO 179-1:2010.

[0057] Mufflers can be formed from polymer compositions using a variety of different techniques. Suitable techniques include, for example, injection molding, low-pressure injection molding, extrusion compression molding, gas injection molding, foam injection molding, low-pressure gas injection molding, low-pressure foam injection molding, gas extrusion compression molding, foam extrusion compression molding, extrusion molding, foam extrusion molding, compression molding, foam compression molding, and gas compression molding. For example, an injection molding system including a mold from which a polymer composition can be injected can be used. The time inside the injector can be controlled and optimized so that the polymer matrix does not solidify beforehand. When the cycle time is reached and the barrel is full for discharge, a piston can be used to inject the composition into the mold cavity. Compression molding systems can also be used. Similar to injection molding, the molding of the polymer composition into a desired article is also carried out in a mold. The composition can be placed into a compression molding mold using any known technique, such as being picked up by an automated robotic arm. The temperature of the mold can be maintained above the solidification temperature of the polymer matrix for a desired period of time to allow solidification. The molded article can then be solidified by lowering the temperature below its melting point. The resulting product can be demolded. The cycle time for each molding process can be adjusted to suit the polymer matrix, to achieve sufficient bonding, and to increase overall process productivity.

[0058] In other embodiments, the muffler may be formed by an additive manufacturing process (e.g., 3D printing). Various types of 3D printing techniques can be used, such as extrusion-based systems (e.g., fused deposition modeling), powder bed fusion, and electrophotography. For example, when used in a fused deposition modeling system, the polymer composition may be used as a constructing material to form the 3D structure and / or as a supporting material to be removed from the 3D structure after it has been formed. Advantageously, a prototype muffler may be fabricated using 3D printing, and this muffler can be tested for its noise reduction characteristics. For example, a proposed muffler design can be 3D printed into a prototype, placed in a computer system, and tested to see if it meets the target values ​​for noise reduction in the relevant frequency band. 3D printing is useful for preparing such rapid prototypes for testing because it generally does not require any tool finishing or the fabrication of mold cavities.

[0059] A muffler generally comprises an inlet, an outlet, a main duct, at least one resonant cavity, and a plurality of apertures that allow airflow between the main duct and the at least one resonant cavity. One embodiment of such a muffler is shown in Figure 1. As shown, the muffler 100 comprises a conical inlet 101, a conical outlet 102, and a main duct 103 extending from the inlet 101 to the outlet 102. The main duct 103 is surrounded by three resonant cavities, 104a, 104b, and 104c. Apertures 105a, 105b, and 105c allow airflow between the main duct 103 and the resonant cavities 104a, 104b, and 104c, respectively. In the embodiment shown in Figure 1, the resonant cavities gradually decrease in size from the inlet 101 to the outlet 102. For example, resonant cavity 104a is larger than 104b, and 104b is larger than 104c. However, it should be understood that there is no limit to the relative size of the cavities. For example, all cavities may be the same size, or they may gradually increase in size from the inlet to the outlet. Similarly, there is no limit to the number of resonant cavities. For example, in some embodiments, there may be only a single resonant cavity, while in other embodiments, there may be more than three.

[0060] A resonant cavity is formed between the inner wall 106 and the outer wall 107. The inner surface of the inner wall 106 defines the main duct 103. The outer surface of the outer wall 107 defines the outer diameter of the muffler 100. The relative size of the resonant cavity in the radial direction can be varied as needed to meet the noise reduction requirements. For example, the ratio (a / b) of the radial length (a) from the inner wall 106 to the outer wall 107 to the diameter (b) of the main duct may be about 0.05 to about 1, about 0.5 to about 0.8 in some embodiments, about 0.1 to about 0.3 in some embodiments, and about 0.15 to about 0.25 in some embodiments.

[0061] In addition, as shown in Figure 1, it can be seen that the resonant chambers 104a, 104b, and 104c extend further axially than the corresponding apertures 105a, 105b, and 105c. However, it should be understood that apertures may extend along the entire length of the resonant chamber, or that there may be multiple apertures axially corresponding to each resonant chamber. For example, the ratio of the axial length of each aperture to the axial length of the corresponding resonant chamber may be about 0.1 to about 1, about 0.5 to about 1 in some embodiments, about 0.6 to about 0.9 in some embodiments, and about 0.7 to about 0.8 in some embodiments. In some embodiments, apertures may constitute about 5% to about 80% of the area on the inner wall of one or more resonant cavities, about 15% to about 75% in some embodiments, about 25% to about 65% in some embodiments, about 30% to about 60% in some embodiments, and about 40% to about 60% in some embodiments. In some embodiments, the thickness of the inner wall may be about 0.5 mm to about 5 mm, and in some embodiments, about 1 mm to about 3 mm.

[0062] If the cooling fan is configured to blow air away from the heat-generating computing component, the muffler outlet can be sized to fit around the cooling fan inlet and up to the size of the cooling fan frame. The diameter of the main duct may be approximately the same as or smaller than the diameter of the cooling fan inlet. If the cooling fan is configured to blow air towards the heat-generating computing component, the muffler inlet can be sized to fit around the cooling fan outlet and up to the size of the cooling fan frame.

[0063] The internal structure of the muffler can be seen more clearly in Figure 2. As shown, the muffler 200 has two inner ring walls 210 that extend radially between the inner wall 206 and the outer wall 207, separating the corresponding resonant chambers 204a, 204b, and 204c from each other. It can also be seen that each resonant chamber is accessible from the main duct 203 by four apertures.

[0064] As shown in Figure 3, in one embodiment, multiple mufflers can be manufactured as an integrated set. Such a set can be inserted into a computer system having the same number of cooling fans in a row. For example, in Figure 3, the muffler set 300 includes six different mufflers 301 that are integrally attached to one another by a connector 302. In addition, the muffler set 300 is mounted on a frame 303 which can be formed to support the mufflers within the chassis of the computer system.

[0065] Figure 4 shows a computer system to which a set of mufflers can be added. System 400 comprises a chassis 401, a cooling fan 402, and a computing component 403. In the system shown in Figure 4, the cooling fan 402 is configured to blow air away from the computing component 403, thereby exhausting warm air and drawing cooler air from the environment into the chassis through a vent 404. Thus, the cooling inlet 406 faces the inside of the chassis 401 and the computing component 403. Computer systems like the one shown in Figure 4 (e.g., rack servers) can be easily stacked together to form a larger system, which may be part of a larger cloud computing data center.

[0066] Figure 5 shows a computer system 500 as shown in Figure 4, in which a set of mufflers 501 is attached to a set of cooling fans 502. The frame of the set of mufflers 501 supports the mufflers and rests on a fan frame 700 (shown in Figure 7) within the chassis 503. In the computer system shown in Figure 5, the set of mufflers 501 corresponds to the cooling fans 502 located on the upper side of the chassis. In some embodiments, there may be multiple levels of cooling fans within the chassis. Mufflers may be attached to all rows or to only some rows. For example, referring to Figure 4, there is space for mufflers on the upper side of the chassis but not on the lower side.

[0067] The muffler can be attached to the fan by any preferred method. For example, the muffler can be attached to the fan using adhesive and rivets. Preferably, there is no gap between the inlet or outlet of each muffler and the inlet or outlet of each fan so that all the air drawn in by the fan passes through the muffler.

[0068] The computer systems shown in Figures 4 and 5 are servers, but it should be understood that a computer system can be any computer system cooled by a cooling fan. For example, a computer system may include any means or set of means capable of operating to compute, classify, process, transmit, receive, retrieve, transmit, switch, store, display, manipulate, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, administrative, entertainment, or other purposes. For example, a computer system may be a personal computer, PDA, consumer electronic device, network storage device, or any other suitable device, and its size, shape, performance, functionality, and price may vary. Thermally generating computing components within a computer system may include one or more processing resources such as random access memory (RAM), a central processing unit (CPU), or hardware or software control logic, ROM, and / or other types of non-volatile memory. Additional components of a computer system may include one or more disk drives, one or more network ports for communicating with external devices, and various input and output (I / O) devices such as a keyboard, mouse, and video display. A computer system may also include one or more buses capable of transmitting communications between various hardware components.

[0069] In a method for reducing noise from cooling fans in a computer system, the system can first be analyzed to determine the noise reduction requirements. During the analysis, the computer system can be operated at the maximum speed of the cooling fan, and the sound pressure level can be measured at the location of the hard disk drive (HDD). Simultaneously, the input / output state of the HDD can be measured to establish a baseline value for the original state. The fan speed, and therefore the sound pressure level, can be manipulated until a critical sound pressure level is found. The critical sound pressure level is the maximum level at which the HDD operates properly. Next, the maximum sound pressure level can be compared to the critical sound pressure level. From this comparison, the frequency at which the maximum sound pressure level exceeds the critical level can be determined. The difference between the maximum sound pressure level and the critical value can be a target value for sound transmission loss within the frequency band covering the frequency at the peak sound pressure level. An exemplary target sound transmission loss profile that can be constructed from the analysis is shown in Figure 6.

[0070] In addition, the maximum volume of the muffler can be determined. In one embodiment, the maximum cross-sectional area of ​​the muffler is the cross-sectional area of ​​the cooling fan frame. The maximum length of the muffler can be determined by extending its maximum cross-section along the direction normal to the inlet / outlet of the cooling fan until interference with other devices or structures occurs. The maximum volume is the product of the maximum cross-sectional area and the maximum length. Figure 7 shows this concept. It can be seen that the maximum width and height correspond to the height and width of the fan frame 700, and the maximum length is determined by extending the cross-sectional area defined by the maximum height and width until another structural component is reached.

[0071] If the target value for sound transmission loss and the maximum volume of the muffler are known, the muffler structure can be designed. In some embodiments, the main duct size is determined using the cross-sectional area of ​​the inlet or outlet of the cooling fan. Also, in some cases, the diameter of the main duct may need to be smaller than the diameter of the inlet / outlet of the cooling fan in order to obtain sufficient volume within the resonant chamber surrounding the main duct.

[0072] In addition, to promote smooth airflow within the muffler and reduce airflow resistance, a conical or curved surface can be used to transition between the smaller inner diameter of the main duct and the diameter of the fan inlet.

[0073] When designing a muffler, the number of resonant cavities can be determined according to the width of the target frequency range so that the sound transmission loss curve formed by connecting each peak can cover as wide a range of the target sound pressure values ​​within the target frequency range as possible. If it is necessary to eliminate a specific sound pressure peak, the sound pressure peak of a specific cavity can be matched to that specific sound pressure peak to achieve the best sound reduction effect.

[0074] The sound pressure peak and corresponding frequency of each cavity are determined by the cavity volume, the area of ​​the opening between the cavity and the main duct, and the thickness of the partition panel between the cavity and the main duct. The shape and total volume of all cavities should be confined to the maximum layout space of the muffler. In the muffler design process, simulation software can be used to predict whether the sound transmission loss of the design meets the noise reduction target requirements. If the sound transmission loss does not meet the target requirements, modified design options can be formed by changing the volume of the corresponding cavity and the size of the opening between the cavity and the main duct. These iterative design and simulation prediction steps can be repeated until the sound transmission loss curve meets the target requirements within the maximum layout space, or until a design option that essentially meets the noise reduction requirements is obtained.

[0075] The muffler design can be optionally validated experimentally. For example, in one embodiment, 3D printing or other rapid prototyping methods are used to create a prototype according to the CAD model of the proposed design. After obtaining the muffler prototype, the muffler can be installed in a computer system by using, for example, hot melt adhesive and rivets to ensure that the muffler and cooling fan are well connected without gaps. The computer system can then be started up, and the noise level and hard disk input / output accuracy can be tested at the maximum fan speed. If successful, the prototype muffler can be used in the system, or the successful design can be reconstructed using a different molding technique (e.g., injection molding).

[0076] These and other modifications and variations of the present invention can be carried out by those skilled in the art without departing from the spirit and scope of the invention. In addition, it should be understood that the various embodiments may be replaced both in whole and in part. Furthermore, those skilled in the art will fully understand that the foregoing description is merely illustrative and is not intended to limit the invention to such further described claims.

[0077] Test method Melting viscosity: The melting viscosity (Pa·s) can be determined according to ISO test No. 11443:20021 using a Dynisco LCR7001 capillary rheometer at a shear rate of 1,000 rpm and a temperature 15°C higher than the melting temperature (e.g., approximately 350°C). The rheometer orifice (die) had a diameter of 1 mm, a length of 20 mm, an L / D ratio of 20.1, and an incidence angle of 180°. The barrel diameter was 9.55 mm + 0.005 mm, and the rod length was 233.4 mm. Melting temperature: The melting temperature ("Tm") can be determined by differential scanning calorimetry ("DSC"), as is well known in the art. The melting temperature is the differential scanning calorimetry (DSC) peak melting temperature determined by ISO test No. 11357-2:2020. The sample was heated and cooled at 20°C per minute, as described in ISO standard 10350, using DSC measurements performed on a TA Q2000 instrument according to the DSC procedure. Temperature of deflection under load ("DTUL"): The temperature of deflection under load can be determined according to ISO Test No. 75-2:2013 (technically equivalent to ASTM D648-18). More specifically, an edgewise three-point bending test may be performed on a test strip specimen having a length of 80 mm, a thickness of 10 mm, and a width of 4 mm, with a specified load (maximum outer fiber stress) of 1.8 megapascals. The specimen is lowered into a silicone oil bath, and the temperature may be increased at 2°C per minute until the deflection of the specimen is 0.25 mm (0.32 mm in ISO Test No. 75-2:2013). Tensile modulus, tensile stress, and tensile elongation: Tensile properties can be tested according to ISO Test No. 527:2019 (technically equivalent to ASTM D638-14). Measurements of modulus and strength can be performed on the same test strip specimen having a length of 80 mm, a thickness of 10 mm, and a width of 4 mm. The test temperature may be 23°C, and the test speed may be 1 or 5 mm / min. Bending modulus, bending stress, and bending elongation: Bending properties can be tested according to ISO Test No. 178:2019 (technically equivalent to ASTM D790-17). This test can be performed on a support span of 64 mm. The test can be performed on the central portion of an uncut ISO 3167 multipurpose bar. The test temperature may be 23°C and the test speed may be 2 mm / min. Charpy impact strength with and without notches: Charpy impact strength can be tested according to ISO test No. ISO 179-1:2010 (technically equivalent to ASTM D6110-10, Method B). This test can be performed using Type 1 specimen size (80 mm in length, 10 mm in width, and 4 mm in thickness). When testing impact strength with notches, the notch may be a Type A notch (base radius of 0.25 mm). The specimen can be cut from the center of a multipurpose bar using a single-tooth milling machine. The test temperature may be 23°C. Tandelta: Here, dynamic mechanical analysis (DMA) is used to determine the storage modulus (E'), the loss modulus (E''), and the glass transition as functions of temperature. The tandelta is the curve that results from viewing the loss modulus divided by the storage modulus (E'' / E') as a function of temperature.

[0078] Dynamic mechanical analysis is discussed in detail in "Dynamic Mechanical Analysis: A Practical Introduction," Menard KP, CRC Press (2008), ISBN 978-1-4200-5312-8. The storage modulus (E') and loss modulus (E'') curves exhibit specific changes depending on the increasing temperature and the molecular transitions occurring in the polymer material. A key transition is called the glass transition. This characterizes the temperature range in which the amorphous phase of the polymer transitions from a glassy state to a rubbery state, exhibiting large-scale molecular motion. Therefore, the glass transition temperature is a specific attribute of the polymer material and its morphological structure. The tan-delta curve shows a prominent peak in this temperature range. This peak tan-delta temperature is defined in the art as the tan-delta glass transition temperature, and the height of the peak is a measure of the crystallinity of the polymer material. Polymer samples with low or no crystallinity exhibit a high tan delta peak due to the large contribution of molecular motion in the amorphous phase, while samples with high levels of crystallinity exhibit a smaller peak because molecules in the crystalline phase cannot exhibit such large-scale rubber-like motion. Therefore, in this specification, the value of the tan delta glass transition peak is used as a comparative index of the level of crystallinity in melt-blended thermoplastic polymer compositions. [Examples]

[0079] Sample 1 was formed from a polymer composition containing 65% by weight of polyamide 6,6 and 35% by weight of glass fibers having approximately 6% tandelta.

[0080] Sample 2 was formed from a polymer composition containing 65% by weight of polyamide 6,6 and 35% by weight of glass fibers having approximately 10% tan delta.

[0081] To test the damping characteristics of the two compositions, samples were formed into rectangular cantilevered specimens, and a free vibration test was performed by deflecting and then releasing the free end of the beam. The acceleration was measured over time using an accelerometer attached to the sample. The resulting acceleration curves are shown in Figure 8. The darker curve is from sample 1, and the brighter curve is from sample 2. As can be seen from the figure, sample 2 exhibited a smaller acceleration than sample 1 and stabilized completely well earlier than sample 1.

Claims

1. A computer system, A chassis housing at least one heat-generating computing component, At least one cooling fan housed within the chassis is configured to convectively cool the at least one heat-generating computing component, At least one muffler positioned at the inlet or outlet of the at least one heat dissipation fan, the muffler comprising an inlet, an outlet, a main duct extending between the inlet and the outlet, at least one resonant chamber surrounding the main duct, and a plurality of apertures within the main duct configured to allow air and sound to flow and be transmitted between the main duct and the at least one resonant chamber, A computer system equipped with the following features.

2. The computer system according to claim 1, wherein the muffler comprises a polymer composition containing a thermoplastic polymer.

3. The computer system according to claim 2, wherein the thermoplastic polymer includes an aliphatic polymer.

4. The computer system according to claim 3, wherein the aliphatic polymer includes an aliphatic polyamide.

5. The computer system according to claim 4, wherein the aliphatic polyamide comprises polyamide 6 and / or polyamide 6,6.

6. The computer system according to claim 2, wherein the polymer composition comprises at least one filler.

7. The computer system according to claim 6, wherein the at least one filler includes glass fiber.

8. The computer system according to claim 6, wherein the at least one filler constitutes about 1% to about 50% by weight of the polymer composition.

9. The computer system according to claim 2, wherein the polymer composition exhibits a tandelta of about 0.1 or more at 60°C when measured using dynamic mechanical analysis.

10. The computer system according to claim 1, wherein the at least one muffler comprises at least two resonant chambers arranged axially apart from one another.

11. The computer system according to claim 1, wherein the ratio (a / b) of the radial length (a) from the inner wall of the at least one resonant chamber to the outer wall of the at least one resonant chamber to the diameter (b) of the main duct is about 0.05 to about 1.

12. The computer system according to claim 1, wherein the diameter of the main duct is less than or equal to the diameter of the inlet or outlet of the at least one heat dissipation fan.

13. The computer system according to claim 1, wherein the inlet and / or outlet of the at least one muffler have a conical shape.

14. The computer system according to claim 1, wherein the at least one resonant chamber is a Helmholtz resonator, a quarter-wave tube resonator, or a resonant cavity.

15. The computer system according to claim 1, wherein the system comprises two or more mufflers integrally connected to one another.

16. A process for reducing noise from a cooling fan in a computer system, wherein the process comprises: The target value for noise reduction is to be obtained within at least one frequency band, To determine the maximum cross-sectional area and maximum length of the muffler, Designing the muffler based on the target values ​​for noise reduction, the maximum cross-sectional area, and the maximum length, wherein the muffler includes an inlet, an outlet, a main duct extending between the inlet and the outlet, at least one resonant chamber surrounding the main duct, and a plurality of apertures within the main duct configured to allow air and sound to flow and be transmitted between the main duct and the at least one resonant chamber. Positioning the muffler at the inlet or outlet of the heat dissipation fan, A process that includes this.

17. The process according to claim 16, wherein the target value is determined by measuring the input / output state of a hard disk housed in the computer system under various noise levels; determining a maximum noise level in a specific frequency band to ensure the normal operation of the hard disk; and calculating the difference between the peak noise level in the frequency band when the cooling fan is operating at maximum speed and the maximum noise level to ensure the normal operation of the hard disk.

18. The process according to claim 16, wherein the maximum outer diameter is equal to the cross-sectional area of ​​the cooling fan, and the maximum length is determined by extending the maximum cross-sectional area along the direction normal to the inlet or outlet of the cooling fan until it interferes with another structure in the computer system.

19. The process according to claim 16, wherein positioning the muffler at the inlet or outlet of the cooling fan includes attaching the muffler to the cooling fan without an air gap using adhesive or welding.

20. The process according to claim 16, wherein designing the muffler includes using software simulations or empirical formulas to predict the acoustic performance of the muffler.

21. The process according to claim 16, further comprising experimentally verifying the design of the muffler by installing the muffler manufactured according to the design into the computer system and verifying whether the noise has been sufficiently reduced.

22. The process according to claim 16, further comprising experimentally verifying the design of the muffler by testing the muffler manufactured in accordance with the design by measuring the sound transmission loss of the muffler outside the computer system and comparing the sound transmission loss with the target value.

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