Abstract: The escape of acoustic energy via an opening in a motor housing penetrated by a steering arm is reduced by installing a pair of acoustic seals. The seals have respective membranes which extend across respective portions of the opening in the housing. These membranes are flexible, self-supporting and substantially block the transmission therethrough of acoustic wave energy in the range of 1,000 to 3,000 hertz. The acoustic seals installed in the housing opening, in combination with a vibro-acoustic treatment applied on the inner surface of the motor housing, suppress noise produced by the motor.

Abstract: To provide a noise absorption blade mounting structure for a working vehicle, which is enabled to be excellent in the draft straightening property in an air hole of the cover of an engine room and excellent in the strength and appearance of the cover, by making noise absorption blades having a high noise absorption effect of a simple structure to mount/demount the noise absorption blades simply in/from the air hole thereby to facilitate the tuning against the noises coming from the engine room and the maintenances of the noise absorption blades. Each of the noise absorption blades 8 includes: a core member 14; noise absorption members 15 mounted on the two faces of the core member 14; and mounting members 11, 12 formed on the end faces of the noise absorption members 15. The cover 6 includes in its air hole 6a straightening members 6e for straightening the draft in front of, as taken in the ventilation direction, the noise absorption blades 8.

Abstract: The vibro-acoustic energy produced by an engine is reduced by shrouding the powerhead with a blanket of material that both damps vibrations and absorbs acoustic wave energy. This vibro-acoustic treatment is applied on the inner surface or surfaces of a motor housing of a propulsion system. The housing is treated by adhering a sheet of acoustic barrier material to the housing inner surface. The acoustic barrier material is designed to block transmission therethrough of a substantial portion of impinging acoustic wave energy in a range from at least 1,000 to 3,000 hertz. The layer of adhesive material has a thickness such that impinging acoustic wave energy in a range of 1,000 to 3,000 hertz is efficiently converted into heat energy. An open-cell foam core laminated to the sheet of acoustic barrier material absorbs the trapped, blocked, acoustic wave energy. The open-cell foam core has an average pore size that is optimized to absorb acoustic wave energy in a range of 1,000 to 3,000 hertz.

Abstract: A sound generating or emitting machine having a component comprising a material with a high internal damping and tensile strength, the material comprising (1) a metallic base material, and (2) a metallic second phase with an at least partially martensitic structure. The material may also be an alloy comprising a base material in which additional alloy elements have a very low solubility.

Abstract: The soundproof casing is divided to an engine room 1, a muffler room 2 and a radiator room 3. The engine room 1 includes the engine E and a work machine unit (generator unit G). The muffler room 2 includes mufflers M1, M2. The radiator room includes a radiator R. An electric fan D is provided between an air intake aperture 22a and the radiator. The radiator room and the muffler room are communicated. An air flow duct 4 to communicate the engine room and the muffler room is provided. An engine fan F is provided just opposite to an entrance of the air flow duct. An inter-cooler I is provided in the air flow duct. The soundproof type engine driven work machine including aforementioned apparatuses is offered to improve the cooling efficiency as well as reducing unfavorable noise.

Abstract: A container for the noise-muffling accommodation of a unit to be installed in a vehicle, such as an electric motor, a pneumatic pump or the like, has two container parts. Each container part is formed by a foam part and is fitted together to form a closed housing. The housing is adapted to be clipped to a vehicle bodywork for assembly on neighbouring parts of the vehicle. A U-shaped holder is partially integrated into one container part. The U-shaped holder is foamed in place. The legs of the U-shaped holder each have a clipping member on mutually opposite wall parts of the container supporting it. The clipping members extend beyond the aperture edge of the container part to clip together the two container parts. A flange projects outwardly from the container walls to secure the container in a gap in the bodywork. Each flange, on its side remote from the respective clipping member, has at least one supporting shoulder projecting laterally outwardly from the container part.

Abstract: A noise suppression louver for an enclosure, in particular, an apparatus for suppressing sound at the openings which allow air to enter or exit an internal combustion engine enclosure. The louver comprises a matrix of intersecting horizontal and vertical passive sound absorptive slats.

Abstract: A noise insulating member having a low degree of water absorbency and a low degree of oil absorbency. The noise insulating member includes a polyurethane foam obtained by reaction of an organic polyisocyanate component and a polyol component in the presence of a fluorine-containing surfactant, and having a cellular network having cells and communication holes which communicate with said cells. The communication holes have respective diameters each of which is not larger than 60 &mgr;m.

Abstract: A vibration damped structure, which is excellent in vibration absorption and sound absorption effect, is provided by coating the surface of a structure to be damped with a mixture of molten photopolymerizable resin and a photopolymerization initiator and then subjecting the coated surface to irradiation, whereby a vibration damping coating is formed on said surface.

Abstract: A soundproofing system is proposed for an electrical machine, in particular a generator. The soundproofing system has a plurality of airtight soundproofing elements mounted releasable attached in an airtight manner using seals and fasteners to a casing frame of the electrical machine. The casing frame being in the form of a framework of the electrical machine. The soundproofing element has a circumferential frame that has a U-shaped profile and is fitted on one side with a covering plate and on the opposite side with a perforated plate. A base surface of the frame governs a height of the soundproofing element. A side surface of the frame acts as a sealing surface with respect to the casing frame of the electrical machine, and the other side surface of the frame is used as a sealing surface for the covering plate. An airborne sound attenuator is inserted between the frame, the covering plate and the perforated plate. The covering plate is mounted in an airtight manner on the sealing surface of the frame.

Abstract: A housing for abating noise and receiving an air cleaner is disclosed. The housing is configured for separable coupling to an internal combustion engine of an automobile. The engine includes a plurality of belt driven accessories driven by a crankshaft. The housing includes an internal air cavity disposed in the housing. The cavity provides an air induction chamber adjacent an intake for inducing air into the air induction chamber from an external source and a filtering chamber adjacent an air discharge for venting air from the filtering chamber. The filtering chamber is configured to receive a filter for purifying air disposed intermediate the intake and the discharge. The engine further includes a shroud integral with the exterior of the housing. The shroud provides a peripheral wall defining a recess configured to at least partially surround at least a portion of at least two belt driven accessories. The shroud substantially reduces noise generated by the engine.

Abstract: An acoustic testing device is relatively small enough and light enough to be transported from business to business and room to room, and yet still has acoustic characteristics sufficient to characterize a test item's noise profile in a relatively short period of time. The device preferably achieves this result by providing inner and outer housings coupled through noise and vibration isolation, the inner housing having at least some mutually non-orthogonal walls, and the sound detection apparatus comprising spatially translating microphones.

Abstract: An enclosure for enclosing sound-producing equipment (such as a marine propulsion system), the enclosure having first and second opposing end panels, first and second opposing side panels, a base and a top panel, releasably connected to each other at corresponding mitered edge joints. The method of making the enclosure includes molding a single enclosure preform and then severing the preform into side, end and top panels. The enclosure preform may be rotationally molded, for example, and may have a layer of sound absorbing material applied to its inner surface during molding. Other, non-molded sound enclosure embodiments are also disclosed.

Abstract: Disclosed a thermal- and sound-insulating container having a chamber, which is defined by multilayer wall structure including vacuum layers therein. The chamber is made as small as possible the surface area thereof to achieve the high insulating effectiveness. The thermal- and sound-insulating container is comprised of the multilayer wall structure with vacuum layers therein, which constitutes the chamber defined in a hollow cylinder partially having a flat secant face, the hollow cylinder having a cross section of a circle or an ellipse that closely resembles the circle. The multilayer wall structure is composed of a pair of confronting frames arranged spaced away from each other, surface panels attached to the frames to define an empty space between the confronting frames, and sealing members arranged between the frames and the peripheries of the surface panels so as to keep the space at vacuum.

Abstract: A window-type air conditioner housing includes a backboard and two parietal sideboards of polystyrene. Each sideboard has a steel plate implant and a coaxial bracing hole for supporting a motor and an associated air conditioner fan bearing components, respectively, to thereby maintain vibration and noise at reduced levels. Preferably each steel plate implant is dimpled in the area surrounding each coaxial bracing hole to strengthen and stiffen the sideboard in that area for supporting the motor and fan assembly.

Abstract: In an internal combustion engine with an engine block, a cylinder head with a camshaft mounted on the engine block, a crankshaft mounted on the engine block opposite the cylinder head and a camshaft timing drive interconnecting the crankshaft and the camshaft, a camshaft timing drive enclosure is disposed at one end of the engine and fully encloses the camshaft timing drive, and the enclosure has extensions extending over the side walls of the engine block and covering openings formed in the side walls of the engine block providing for a light-weight arrangement with noise attenuating properties.

Abstract: A compact engine-operated generator unit has instruments in a soundproof case arranged efficiently from the viewpoint of measures for sound and heat abatement. Particularly, the engine-operated generator unit includes the engine and the generator driven by the engine arranged in a direction of a rotary shaft linking the engine and the generator and the soundproof case accommodates the engine, the generator and other components of the unit therein. An interior of the soundproof case is partitioned into front, center and rear compartments by plate-like front and rear frame members; a through hole is formed in the rear frame member; a duct is provided in the through hole swelling out toward the center compartment and the rear compartment; the generator, the engine and a muffler are accommodated in the duct; a fuel tank and suction system instruments are disposed outside of the duct within the center compartment; and electric instruments are disposed within the front compartment.

Abstract: An upper housing shell of a hermetically sealed refrigeration compressor has a central asymmetrical section interposed between a lower cylindrical section and an upper spherical section. The shape of the central section is such that opposite points define a line that is perpendicular to the surface at one point, but is not perpendicular to the surface at the opposite point.

Abstract: An air induction unit is composed of an air filter, a resinous intake manifold for inducting air filtered by the air filter into intake ports of the engine, a resinous case and a resinous cap. The air filter, intake manifold and fuel injectors are disposed inside the resinous case and the resinous cap. The resinous case and the resinous cap have respectively double-wall structure composed of inside walls and outside walls and noise-and-heat-insulation members between the inside walls and the outside walls.

Abstract: An enclosure for acoustically insulating noise-producing equipment, such as an engine or generator, includes a base, first and second opposing end panels, first and second opposing side panels, and a top panel. The side and end panels rest upon the base and are releasably interconnected at mitered edge joints. The top panel is releasably connected to the end and side panels at similar mitered edge joints. The top, side and end panels are each separately removable from the enclosure without removing any other of the panels, enabling unobstructed access to all sides of the enclosed equipment. Guide pins at the mitered joints align the panels. Methods of use are also disclosed.

Abstract: An oil free compressor uses special structure to interface the engine and compressor. Special quieting structure is also disclosed, including an upward exhaust mechanism, to maintain quiet operation.

Abstract: A system and method of attenuating noise generated in a multicylinder internal combustion engine as a result of opening and closing of the exhaust and intake valves in which cross passages extend between regions of the exhaust and intake manifolds adjacent the exhaust and intake valves of different cylinders in which the exhaust and intake valves open at approximately the same time. The acoustic waves of the noise caused by opening of the exhaust and intake valves respectively are set in mutual opposition to each other to thereby substantially cancel each other. A low mass flexible diaphragm in each cross passage prevents cross flow of exhaust gases while allowing transmission of the acoustic waves. Porous plugs restrict flow to the diaphragm while being sufficiently open to allow free transmission of the noise sound waves to the diaphragm to not impair the mutual cancellation process.

Abstract: An acoustical enclosure for an engine generator set which can be easily assembled and disassembled, as well as assembled and disassembled in close quarters. The assembly and disassembly can be accomplished without special tools. The enclosure is constructed in a manner to afford a change in size or configuration without a change in tooling. The rail/frame construction allows removal of side, end and top panels thus simplifying maintenance.

Abstract: A lightweight acoustic enclosure (1.1), for the reduction of noise transmission from monopole, quadrapole and higher order noise sources via airborne paths at frequencies lower than the approximate ring frequency of the enclosure (1.1), comprising an approximately spherical shaped enclosure (1.1), which is made from stiff materials to reduce the amount of stretching of the enclosure wall and substantially encases the noise source, all structural paths between the enclosure and the noise source comprising vibration isolation (2.4). The thickness of the enclosure wall can be relatively thin. The enclosure (1.1) can comprise multiple concentric layers of stiff material, ideally with adjacent layers having at least one compliant layer, such as foam rubber, sandwiched between them. The enclosure (1.1) can comprise several component parts such as spherical shell elements (1.2), with radii less than that of the approximate radius of the enclosure (1.1). Additional webbings or flanges (1.

Abstract: In a generator assembly, outside air, taken from a suction hole into a fixed soundproof housing, is sucked into a portable engine generator covered by a soundproof case to operate an engine and cool the interior of the fixed soundproof housing. The exhaust gas of the engine and the cooling air of the soundproof case are exhausted outside through the exhaust air hole of the soundproof case and the external exhaust hole of the fixed soundproof housing without leaking into the fixed soundproof housing. Therefore, the portable engine generator can be operated while it remains housed within the fixed soundproof housing. The exhaust air duct of the portable engine generator and the communicating duct of the fixed soundproof housing are communicated in a state of close contact, at the time that the portable engine generator has been positioned by a positioning member provided in the fixed soundproof housing.

Abstract: In a utility vehicle, a muffler accommodating chamber is defined in front of and below an engine mounted at a front portion of a vehicle frame. A rear wall of the muffler accommodating chamber is formed by a front axle frame which is mounted to extend between both of vertical frame portions of the vehicle frame and supports a front axle beam for rotatably supporting front wheels at its opposite ends. The front axle frame has a function to support the front axle beam, a function as a strength member in the form of a cross member, and a function as a member defining the muffler accommodating chamber. A driving gear is mounted to a steering shaft and thrust-supported by a lower surface of a support portion of a support frame which is fixedly mounted on the vehicle frame. A driven gear meshed with the driving gear and a pitman arm are connected to a rotary shaft whose axially upward movement is limited by the support portion and whose axially downward movement is limited by a bracket mounted to the vehicle frame.

Abstract: The ventilation apparatus (51) of the present invention provides an airflow control system that is designed to minimize noise while providing adequate airflow both during engine operation and after engine shutdown. The enclosure (24) that is divided into first and second compartments (26,28). The first compartment (26) houses the drive train components (14) and the second compartment (28) houses the fluid cooling apparatus (30). The first compartment (26) is provided with at least one air communicating means (52) to transfer ambient air from outside the enclosure through a circuitous air passageway (54) lined with sound absorptive material (60,62). The air passageway (54) is formed in at least one of the walls that forms the first compartment (26) so that it may be critically positioned with respect to the more heat sensitive components (14) housed within the enclosure (24) yet maximizing the efficient use of available space.

Abstract: A generator set includes a permanent soundproof housing for housing a portable engine generator therein. The portable engine generator has wheels for moving the same and can be operated in the permanent soundproof housing. The portable engine generator can be taken out of the permanent soundproof housing by pulling the portable engine generator out of the permanent soundproof housing in a direction transverse to a direction of advance of the wheels, and thereafter moving the portable engine generator in the direction of advance of the wheels.

Abstract: An engine compartment casing element (1), in particular for sound absorption, with a foamed material element (2) attached to a wall element (3) which is preferably reverberant, the foamed material element (2) having a skin-like covering (5) on the side facing away from the wall element (3). The foamed material element (2) is perforated, the foamed material element (2) is also covered on both sides with an air-impermeable plastic sheeting (5) or (6) respectively which also covers the perforated areas (holes 4), and the foamed material element (2) is installed so that it runs at least in part at a distance (a) from the wall element (3).

Abstract: A sound attenuator for an enclosure, in particular, an apparatus for attenuating the sound at the openings which allow air to enter and exit an internal combustion engine enclosure with minimal pressure loss. The attenuator comprises a combination of passive sound absorptive louvers place in series with a plurality of reactive Helmholtz resonator units mounted in parallel rows in the open area between each pair of louver. The Helmholtz resonators being tuned to attenuate a single or multiple low frequency noise spikes. The attenuator providing improved sound attenuation and requiring substantially less volume than a typically used absduct type silencer.

Abstract: An auxiliary power system includes an engine balance system, an integrated alternator/starter, a thermal management system, noise-vibration-harshness control system, an emissions/fuel economy system, an APU master control unit, and a vehicle control system.

Abstract: A soundproof type water-cooled engine generator is constructed to guide an exhaust current of air from a cooling fan of a water-cooled engine to an independent hood-like shroud chamber, deaden the current sound through a muffler located under the shroud chamber, for improving the cooling performance. A water-cooled engine 2 and a generator 3 are accommodated in a soundproof bonnet 1. A panel wall 8 is provided close to a fan 7 equipped in the water-cooled engine. The panel wall serves to partition the soundproof bonnet 1 into an engine and generator chamber 11 and an exhaust processing chamber 12. The panel wall has a hole having the substantially same diameter as the fan 7. Around the outside of the hole, a shroud chamber 17 is independently provided in the exhaust processing chamber. The shroud chamber 17 is formed by a hood-like encircling wall 14. On the lateral side of the shroud chamber, a radiator 13 is located to stand upright.

Abstract: A trailerable engine housing 10 for a heat and noise emitting engine 68 is provided, formed of an open topped container having pyramidally shaped end walls 22, 24, side walls 14, 16, and a base plate 42. The open topped container is divided into two separate enclosures by an enclosure baffle 58. A pair of vent panel 28, 30, are held in angled spaced relationship to the pyramidal side edges of the end walls to form an air induction vent hole open to one enclosure and a hot air exhaust hole open to the other. Inducted air is transferred from one enclosure to the other through an enclosure baffle vent hole. Sonic energy may not pass through either the induction air or the hot air exhaust vent holes without first being reflected off a surface within the engine housing.

Abstract: Most existing noise reduction enclosures used with engines and engine driven equipment have failed to meet the reduced noise emission requirements of today and of the future. A few of the present enclosures meet the reduced noise emission requirements of today and of the future but are extremely expensive to purchase and are large bulky structures. The subject enclosure (10) is reasonably priced and provides an enclosure which is effective in reducing the noise emitted therefrom. The enclosure (10) includes a housing (32) having a generally rectangular configuration and being divided into an engine portion (56) defining an engine compartment (57) and a duct portion (54). The outlet ducts (88) having a length greater than the inlet ducts (84). To further enhance the noise reduction of the enclosure (10) a plurality of dynastic hardware is attached to the housing (32).

Abstract: An engine generator set apparatus including an internal combustion engine including a drive shaft driving an electrical generator, the engine and the generator being disposed along a longitudinal axis. A housing substantially enclosing the engine and generator, the housing including air inlets and air outlets. A fan drawing outside ambient air through the air inlets in the housing and along an inlet air pathway, the generator being axially disposed intermediate of the fan and the engine.

Abstract: Most existing noise reduction enclosures used with engines and engine driven equipment have failed to meet the reduced noise emission requirements of today and of the future. A few of the present enclosures meet the reduced noise emission requirements of today and of the future but are extremely expensive to purchase and are large bulky structures. The subject enclosure (10) is reasonably priced and provides an enclosure which is effective in reducing the noise emitted therefrom. The enclosure (10) includes a housing (32) having a generally rectangular configuration and being divided into an engine portion (56) defining an engine compartment (57) and a duct portion (54). The outlet ducts (88) having a length greater than the inlet ducts (84). To further enhance the noise reduction of the enclosure (10) a plurality of dynastic hardware is attached to the housing (32).

Abstract: A sound muffling device for use in lawnmowers includes a hollow body containing an aperture plate, a plurality of serpentine configured pipes, a plurality of fans, a double net having a bundle of wires, and a microporous plate, an adaptor having a sound inlet disposed on the exterior of the front end of the hollow body, and a sound outlet of the exterior of a rear end of the hollow body.

Abstract: A sound wave absorbing air intake baffle is provided for reducing the level of sound reaching an operator on a vehicle having an air cooled engine with an upwardly opening air intake passage in the hood. The baffle includes first and second chambers carrying sound absorbing material and a sound wave deflecting structure spanning the air intake opening for deflecting sound waves into the chambers. To permit cooling air to be drawn through the passage around the deflecting structure and into the engine compartment, an air deflecting structure is positioned above the sound wave deflecting structure.

Abstract: A cooling system is provided for enclosed first and second heat sources including an enclosure substantially enclosing the heat sources. The first and second heat sources are positioned in the enclosure. A heat exchanger, also positioned within the enclosure, is connected through the enclosure to an external source of cooling fluid and is adapted for cooling air within the enclosure. The heat exchanger has a first surface for receiving the air to be cooled and a second surface for expelling cooled air. First and second air circulation means are provided within the enclosure for circulating air past both the first and second heat sources and the heat exchanger. A first baffle portion separates the first and second heat sources and extends to the first surface of the heat exchanger, and a second baffle portion extends to the second surface of the heat exchanger.

Abstract: A number of embodiments of air cooled compact power supplies having air inlet and air outlet openings in the lower portion of the housing of the power supply. The interior of the power supply is baffled so that the air flowing through it must follow a serpentine path to prevent air entrained foreign materials from impinging upon the engine.

Abstract: The invention relates to a combination power and heat unit with a bedplate (1), flanged-together machines (2, 3), a noise suppressor (8), an exhaust-gas heat exchanger (9), a cooling-water heat exchanger (19) as well as the associated auxiliary apparatus and piping, wherein the bedplate (1) shelters the noise suppressor (8) and the exhaust-gas heat exchanger (9) along its opposite longitudinal sides below the machines (2, 3), which are elastically supported on the bedplate (1).

Abstract: An internal combustion engine includes a sound-proofing casing, and a silencer arranged in a separate chamber within the casing such that it does not touch the walls of the separate chamber. Fresh cooling air passes through an inlet opening from the interior of said casing into the separate chamber, and spent cooling air from said separate chamber passes back into the air flowing within the casing, whereby all of the spent air flows from the interior of the sound-proofing casing through an outlet opening of said casing to the outside.

Abstract: A cooling system is provided for an enclosed heat source including an enclosure substantially enclosing the heat source. The heat source is positioned in the enclosure. A heat exchanger, also positioned within the enclosure, is connected through the enclosure to an external source of cooling fluid and is adapted for cooling air within the enclosure. Air circulation means are provided within the enclosure for circulating air past both the heat source and the heat exchanger. A method of cooling an air cooled heat source within an enclosure is also provided.

Abstract: An internal combustion engine has a casing which includes interconnected elements and is connected to an engine housing with interposed vibration-damping means. The engine also has a cooling air blower driven by an engine crankshaft which draws in cooling air through an inlet opening in said casing and conveys such cooling air through an interior space between the engine housing and the casing. Exhaust air from such interior space exits through an outlet opening in said casing, the inlet and outlet openings being disposed in a single element of the casing which element is a closed unit at a side of the engine remote from the blower and is equipped with at least one sound-damping layer. The sound-damping layer has casing element passages formed therein which are separate from one another and which communicate said interior space respectively with the inlet and outlet openings.

Abstract: A power thermo-coupling unit with muffler (4, 5) and exhaust gas heat exchanger (6, 7) avoids the requirement of a disproportionately large space for component removal at the front end of the power thermo-coupling unit. The muffler (4, 5) and the exhaust gas heat exchanger (6, 7) each have two separate components, the lengths of which are shorter than the distances between the center column (8) and the end walls of the unit support (1).

Abstract: A rupture prevention ring consists of two coaxially arranged, spaced-apart stiff end rings wrapped in several layers of fiber cloth. Resin bonding is used around the end rings while in the intermediate area between the end rings, the fibers are not free of resin and hence not stiffened. Owing to the high energy absorption capability of the structure including the elastic yielding of the fibers without the resin, an excellent containment ability is obtained at a low weight. Fragments are effectively retained without jeopardizing the rotating blade and disk assembly of the damaged stage.

Abstract: A vehicle with a noise-damped drive assembly is disclosed which includes a liquid-cooled internal combustion engine having a radiator with a cooling fluid running therethrough and located in a stream of air. An exhaust manifold having a drive assembly connected thereto is provided. The drive assembly is surrounded by a noise-damping case which has at least one air inlet opening located in a lower front portion of the case in a direction of travel of the vehicle. The case also has at least one air outlet opening located in an upper back portion of the case in the direction of travel. The radiator and exhaust manifold located outside of the case.

Abstract: The invention concerns constrained layer sound damping. A composition and a laminated structure are provided for the reduction of noise coming from housings such as oil pans for automobiles. The composition comprises a rubbery polyurethane, an olefin polymer, and a filler. The laminated structure comprises the housing, the composition, and a sheet metal liner. The composition contains a blowing agent which is activated to provide a single unitary structure which dampens noise. The polyurethane and olefin polymer are thoroughly intermixed with each other, but maintain their separate identities in the blend.

Abstract: A noise reducing apparatus in the form of a hollow body comprising two or more passage groups consisting of a plurality of passages. The length of each passage is determined such that the sound waves emitted from the passages of the adjacent passage groups form plane waves which are shifted by a half wavelength so that plane waves interfere each other. The apparatus can be secured to an opening of construction and reduce the level of sound pressure from a sound source without any closed shield construction surrounding the sound source.

Abstract: An internal combustion engine is provided with a sound-insulating enclosure (2), which defines a sealed passage extending through the enclosure. A passage which extends through the enclosure is sealed by a sealing ring (9), which consists of a rubber-elastic material and is disposed between an inner flanged ring (7), which is secured to the engine, and an outer flanged ring (8), which is secured to the enclosure (2). In order to provide sealing means which are satisfactory for a passage for the exhaust manifold (3), the inner flanged ring (7) carries a protective shield (10), which shields the inside surface of the sealing ring (9) and which defines with the sealing ring (9) a clearance (12), which contains a heat-resisting and sound-absorbing insulating material (11).