Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
  • F04B39/0027—Pulsation and noise damping means
  • F04B39/0044—Pulsation and noise damping means with vibration damping supports
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
  • F04B39/12—Casings; Cylinders; Cylinder heads; Fluid connections
  • F04B39/127—Mounting of a cylinder block in a casing

Definitions

• the present invention refers to a noise absorbing composite, which is chemically and physically resistant, for a suspension system usually employed in compressors, motors or any other similar apparatus of hermetic construction, which functioning causes vibrations, associated with undesirable high frequency noises. Said material is particularly applied in reciprocating hermetic compressors used in refrigerating units.
• Reciprocating hermetic compressors are conventionally provided with a suspension system, which uses springs or other adequate means to insulate the vibrations of the motor-pump assembly from its hermetic case.
• the hermetic compressor presents its motor-pump assembly fastened through suspension metallic springs, which are attached to the upper portion of the compressor case and which functions under tension, or through supporting springs, which are attached under compression to the base of the case.
• the sound-absorbing elastomeric systems of the state of the art do not present such characteristics of physical and chemical resistance, and undesirable high frequency noises are often present substantially soon in their useful lives, due to thermal and/or chemical decomposition and/or deformations in the noise absorbing means which are used.
• the known elastomeric systems present limited sound- absorbing capacity, according to assays carried out by the inventor of the present invention with several known products, such as: acrylic-ethylene copolymers, halogenated hydrocarbons, butadienes and acrylonitrile- butadienes in suspension components having the same geometry, in which the values obtained for the total reduction of noise in the compressor were of about 1-3 decibels. Disclosure of the Invention
• a noise absorbing composite for the suspension system of a reciprocating hermetic compressor, said suspension system being of the type defined by metallic helical springs, which interconnect the fixed case of a hermetic compressor with its motor-pump assembly, usually with undesirable high frequency noises, said noise-absorbing composite being defined by a portion of a viscoelastic material, in close and permanent contact with a substantial portion of said spring surface, said viscoelastic material at least comprising: - a main elastomeric portion, defined by 100 parts of a compound, which is selected from the group consisting of: polysiloxanes, tetracyclosiloxanes, pentacyclosiloxanes or mixtures thereof; - a portion of vulcanization, defined from 0.2 to 6.0 phr of a compound selected from the group consisting of: di-cumile peroxide; 2.5-bis (ter-butyl) peroxide; 2.5 dimethylhex
• Fig. l illustrates, schematically, a lateral elevational view of a reciprocating hermetic compressor, in which the motor-pump assembly is attached to the case through suspension metallic springs under tension
• Fig. 2 shows a similar view of fig.l, but with the motor-pump assembly attached to the case through supporting metallic springs under compression
• Fig. 3 is a diametral longitudinal section view of an absorbing element in the form of an elongated plug of cylindrical shape, which can be fitted within a suspension or a supporting spring and which is provided with an axial bore, in order to receive an expander, thereby increasing its radial compression against the spring
• Fig. 4 illustrates a diametral longitudinal section view of a suspension or supporting metallic helical spring, whose coils are all internally covered with an absorbing element, which is substantially cylindrical and adapted within the spring. Best Mode of Carrying out the Invention
• the suspension system of the motor-pump assembly 1 in the case 2 of a reciprocating hermetic compressor may present two basic constructive dispositions: suspension metallic springs 3A, which are attached to the upper part of the case 2 of the compressor and which operate under tension; and supporting metallic springs 3B, which are attached under compression to the base of the case 2.
• suspension metallic springs 3A which are attached to the case 2, through supporting means 5 welded to the upper part of said case.
• lubricant oil 6 which can be mineral or synthetic and whose chemical material usually presents highly aggressive components for most elastomeric materials in the form of organic compounds, whether they are hydrogenated or non-hydrogenated, and/or sulphonated or non-sulphonated, or others.
• the proposed material besides having remarkable chemical and thermal resistance, under temperatures up to 200°C (392°F) , associated with a unique dimensional constancy, allows a reduction in the noise amplitude in the frequency with of 400 to 8,000 Hz, and a total noise reduction in the compressor of about 4 decibels, such characteristics lasting during the whole useful life of the compressor.
• a noise absorbing composite for a suspension system of reciprocating hermetic compressors of the present invention can be applied to a spring, which interconnects the motor-pump assembly 1 of the compressor with the case 2 thereof, said composite having the form of a cylindrical plug 10, which is attached internally to said spring 3, by the simultaneous radial action of the partial fitting of the internal surface of the wire of the spring 3 against the external contact surface of said plug of the sound-absorbing material 10 of the invention, together with a resilient compression of said plug against said spring 3, in order to allow a permanent contact between both surfaces, thus assuring the mutual retention of said spring 3 and plug 10.
• the noise absorbing composite of the present invention presents the form of an elongated plug 20, of a substantially cylindrical shape, dimensioned to be fitted within the spring 3, with its lateral wall exerting a certain radial compression over the coils of said spring.
• Such compression is achieved by the own elasticity of the plug 20, and by the level of compression thereof inside the spring and/or by introducing an expander in an axial bore 21, which is provided on at least one of the ends of said plug 20.
• the noise absorbing composite can present the following alternative forms:
• the material of the proposed material can absorb the high frequency vibrations of the spring coils, thereby minimizing the propagation resonance in this range of frequencies.
• the noise absorbing composite for the suspension system of reciprocating hermetic compressors of this invention which has a substantially viscoelastic consistency, which presents the aforementioned advantages and which can be applied as described above, comprises a main elastomeric portion, defined by 100 parts of a compound consisting of: polysiloxanes, tetracyclosiloxanes, pentacyclosiloxanes or mixtures thereof, said main elastomeric portion preferably comprising 100 parts of a fluorinated polysiloxane. If any alternative compound is used, it will be incorporated in the same amount.
• a portion of vulcanization is incorporated, defined by 0.2 to 6.0 phr (parts by 100 parts of elastomer) and, preferably, from 0.8 to 1.3 phr of a compound selected from the group consisting of di-cumile, 2.5-bis (ter-butyl) peroxide, 2.5- dimethylhexane, or mixture thereof.
• the vulcanization portion comprises from 0.8 to 1.3 phr of di-cumile peroxide, with 93 to 99% purity, preferably 99% purity.
• a basic viscoelastic material such as that obtained above, presents a hardness between 20 and 50 shore A, preferably between 30 and 40 shore A, where the maximum hardness corresponds to a maximum specified incorporation of the vulcanization portion in the basic viscoelastic material, and vice-versa.
• Said basic viscoelastic material actually has the advantages required for the material in question, except for its thermal resistance, which is still unsatisfactory in extreme operational conditions.
• thermo-resistant portion should be incorporated in the basic viscoelastic material, said portion being defined by 0.0 to 6.0 phr and, preferably, from 0.8 to 1.3 phr of polysiloxanes, whose maximum amount imparts maximum resistance, under high temperatures, to the noise absorbing composite of the present invention, and vice-versa, within the pre- established limits.
• the proposed absorbing composite depends on a specific mixture, within the limits established for each component, for each application of the compressor, being thus determined case by case, due to the range of requirements.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Compressor (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1992
  • 1992-08-20 BR BR9203332A patent/BR9203332A/pt not_active IP Right Cessation
• 1993
  • 1993-08-19 DE DE69302082T patent/DE69302082D1/de not_active Expired - Lifetime
  • 1993-08-19 JP JP6505697A patent/JPH07500402A/ja active Pending
  • 1993-08-19 CN CN 93116452 patent/CN1085581A/zh active Pending
  • 1993-08-19 WO PCT/BR1993/000028 patent/WO1994004822A1/en not_active Ceased
  • 1993-08-19 EP EP93917466A patent/EP0608403B1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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