Abstract: An attachment device includes a support table member and a coupling mechanism. The coupling mechanism includes a coupling bolt and an abutment member having a nut portion. In the abutment member, there is formed a locking protrusion protruding to the side where an auxiliary machine fixing portion is present. In the auxiliary machine fixing portion, there is formed an insertion hole for the coupling bolt and an anti-rotation hole in which the locking protrusion can be fitted.

Abstract: An exhaust gas muffler, for an exhaust system of an internal combustion engine, includes a muffler housing (12) with a circumferential wall (14) elongated in a housing axis (L) direction and with an end wall (20, 22) at each axial end area (16, 18). Two exhaust gas pipe holding openings (44, 46) are provided in the circumferential wall (14) with an exhaust gas pipe (40) fixed to the circumferential wall (14) in an area of each exhaust gas pipe holding opening (44, 46) and open towards a housing interior (24). The exhaust gas pipe (40) is preferably closed at one end area (54) by a closing element (58). The exhaust gas pipe (40) has at least one exhaust gas passage opening (66) in a length area (64) extending between the two exhaust gas pipe holding openings (44, 46).

Abstract: A system for attenuating acoustic energy in machines is provided. The system may include an inner tube disposed about a central axis, an outer tube disposed about the inner tube and the central axis, and a middle tube disposed about the central axis and between the inner tube and the outer tube. The system may also include a first annular ring extending radially from the outer tube and configured to couple the outer tube to the middle tube. The system may further include a second annular ring extending radially from the inner tube and configured to couple the inner tube to the outer tube, such that an acoustic resonator may be formed by the first annular ring, the second annular ring, a portion of the inner tube, a portion of the outer tube, and a portion of the middle tube.

Abstract: A slip-type active noise control muffler reducing exhaust noise of a vehicle may include at least two guides connected to an inner wall of a housing accommodating exhaust gas in the muffler and formed in a pipe shape in a longitudinal direction of the muffler, and a baffle positioned in a plane shape partitioning the interior of the housing and including an electromagnet on the plane shape to control an interval of the baffles through a movement signal by current applied to the electromagnet according to frequency calculated from the exhaust gas, in which the interval of the baffles may be controlled and the exhaust noise may be reduced by controlling the number of wavelengths depending on the frequency.

Abstract: A ball valve may include a control element including a perforated screen disposed within the control element and spaced apart from an inner surface of the control element to form an annular space and a plurality of chambers disposed within the control element. When fluid flows through the control element, sound waves pass through the perforated screen and are reflected back by the plurality of chambers to disrupt other sound waves, thereby reducing fluid noise in the rotary valve.

Abstract: A fan case for a gas turbine engine includes a fan case surrounding a fan with fan blades. A liner is disposed between the fan case and the fan and is spaced a radial distance from the fan case. A torque stop is arranged between the fan case and the liner. A method for reducing fan case liner loads is also disclosed.

Abstract: An internal combustion (IC) power plant includes an IC engine and an exhaust system carrying exhaust gasses from the IC engine to an outlet communicating to the atmosphere.

Abstract: In an exhaust muffler using a double communicating tube as a communicating tube between expansion chambers, the exhaust muffler controls exhaust gas so as not to flow directly between intake and exhaust ports of an inner communicating tube and an outer communicating tube to thereby utilize the volume of the expansion chamber sufficiently. On one end side of the double communicating tube facing into a second expansion chamber, a distal end opening of the inner communicating tube functions as an intake port of an inside passage. A closing member for closing an end in the axial direction of an annular passage is provided in or in the vicinity of a distal end opening of the outer communicating tube. An exhaust port for opening the annular passage outwardly in the radial direction is provided between the closing member of the outer communicating tube and a first partition wall.

Abstract: Monolithic acoustically-treated composite structures and methods for fabricating the same are provided. A monolithic acoustically-treated composite structure comprises an internal frame assembly comprising a unitary composite frame structure and at least one acoustic panel assembly. The unitary composite frame structure defines a shape of the monolithic acoustically-treated composite structure to be fabricated. A composite overlay covers the internal frame assembly. The method for fabricating the monolithic acoustically-treated composite structure comprises forming the unitary composite frame structure, including the at least one acoustic panel in the unitary composite frame structure, and covering the internal frame assembly with the composite overlay.

Abstract: A muffler shell is formed from a sheet metal blank. The shell comprises a tubular body section which is rolled into a tube so that a first edge of the blank can be welded to an intermediate seam line across the blank. An aerodynamic shield extension projects integrally from the tubular body section between the intermediate seam line and a second edge of the blank to cover a gap between the muffler and adjacent structures when installed on a vehicle.

Abstract: The present invention relates to a silencer system for a vacuum motor in a suction cleaner, which may be constructed using only one or two parts to form a housing for the vacuum motor including the silencer system. The system may have a main fan silencer system for the main fan and a second motor cooling silencer system for the motor cooling fan. The main fan is encapsulated in a housing surrounded by a substantially circular first wall part in such a way that a first cavity is formed between the housing and the first wall part. The system further includes two ducts, each duct connected at one end with a serpentine shaped exhaust air duct and at the other end with a second cavity connected with the first cavity by an opening in the first wall part.

Abstract: The present invention relates to a silencer duct for a ship's propeller using resonant barrels, wherein the ship's propeller is surrounded by the silencer duct so as to deaden underwater noises of various frequencies generated by the propeller, the duct being made into a cylindrical form to surround the propeller arranged in the side or rear part of the ship so as to guide the fluid direction as the propeller rotates, and the inside of the duct being provided with a plurality of resonant barrels for damping resonant frequencies arranged in the form of n×m (herein, n and m are natural numbers except 0) so as to damp the sound waves generated by the rotation of the propeller.

Abstract: A saddle-ride type vehicle which includes catalyst devices in left and right exhaust flow passages can suppress effect of the catalyst devices on the reach to the ground even if the sizes of catalysts are large. The vehicle includes: exhaust flow passages connected to a multi-cylinder engine and disposed independently on left and right sides of a vehicle body; a first catalyst device provided in a middle of the left exhaust flow passage; a second catalyst device provided in a middle of the right exhaust flow passage; a swing arm pivotally supporting a rear wheel such that the rear wheel is swingable, the saddle-ride type vehicle includes silencers connected to portions of the exhaust flow passages downstream of the first catalyst device and the second catalyst device, and the first catalyst device and the second catalyst device are arranged side by side below the swing arm.

Abstract: A fluid line includes a resonator having an inner part and a blow-molded outer part defining an inner surface. The inner and outer parts are fixedly connected. The inner part is an injection-molded part having first and second radial collars spaced axially apart from each other. The inner part defines a radial circumference with a plurality of orifices formed therein. The inner and outer parts are axially one within the other so that there is no throughflow of secondary air between the first and second radial collars and the inner surface of the outer part. The inner and outer parts have a common end whereat they are airtightly connected to each other. The inner part, the radial collars and the inner surface of the outer part conjointly define two resonant chambers operatively connected to fluid in the fluid line via the orifices.

Abstract: A system for reducing noise emissions in underwater environments is presented. The system can be extended to applications in any two-fluid environments where one fluid (gas) is contained in an enclosed resonator volume connected to the outside environment at an open end of the resonator body. The resonators act as gas-containing (e.g., air) Helmholtz resonators constructed into solid panels that are submerged in the fluid medium (e.g., sea water) in the vicinity of a noise generating source. The oscillations of the trapped air volume in the resonators causes reduction of certain noise energy and a general reduction in the transmitted noise in the environment of the system.

Abstract: An exhaust muffler for a vehicle includes: a sleeve portion made up of an outer sleeve and an inner sleeve; an upstream side cover that has an exhaust entrance and that closes an upstream side opening of the sleeve portion; and a downstream side cover that has an exhaust exit and that closes a downstream side opening of the sleeve portion. At least one of the upstream side cover and the downstream side cover has a peripheral flange portion that externally holds the sleeve portion. The peripheral flange portion has an outer sleeve holding portion and an inner sleeve holding portion. One end portion of the inner sleeve abuts on the inner sleeve holding portion so as to be slidable in a length direction of the inner sleeve. One end portion of the outer sleeve is fixed to the outer sleeve holding portion.

Abstract: Exhaust apparatus for four cycle (including Wankel) internal combustion engines is disclosed. The apparatus is configured to manage pressure waves created by expanding gas emitted from the engine combustion chambers, the net result being to enhance engine performance and attenuate noise over a wide range of engine RPMs.

Abstract: The present invention relates to a silencer device for a fluid line which comprises a resonator arrangement which comprises a first resonator tube comprising a first resonator chamber designed for a ?/4 damping of at least one sound wavelength, wherein the first resonator tube comprises a first longitudinal direction, two end walls facing each other in the first longitudinal direction and a first side wall extending between the end walls, and wherein the first resonator chamber is formed between the first side wall and the end walls of the first resonator tube.

Abstract: An adsorption unit for combustion gas of an internal combustion engine has an adsorption housing having a chamber section with an inner wall. An adsorption element disposed in the adsorption housing is made of a gas-permeable adsorption medium that is formed to a hollow body and encloses an interior of the adsorption element. The hollow body has opposed open ends. A main flow passage extends through the hollow body and the combustion gas flows in main flow direction through the hollow body. The adsorption element has an exterior circumferential side facing away from the interior and delimiting together with the inner wall of the chamber section a bypass chamber surrounding the absorption element outwardly. In the main flow direction, the bypass chamber has a downstream end that is closed off and an upstream end that has at least one bypass opening that communicates with the main flow passage.

Abstract: The invention relates to an exhaust gas treatment device for an exhaust system of a combustion engine, more preferably of a road vehicle, with a housing enveloping at least one interior space, and with at least one through-pipe penetrating the interior space without interruption and which at two fastening points distant from each other is connected to the housing in a fixed manner. For compensating thermally related expansion effects the through-pipe between the fastening points can comprise at least one expansion compensation section, in which a wall of the through-pipe comprises slits penetrating the wall alternating in circumferential direction and strips protruding relative to adjacent wall sections of the through-pipe.

Abstract: The present invention refers to an acoustic filter for reciprocating compressor and, in special, a suction acoustic filter containing at least one inlet pipeline (21), at least one outlet pipeline (22), and at least one intermediate pipeline (42). Said acoustic filter (1) comprises at least two horizontal chambers (5, 6), wherein said chambers are interconnected by an intermediate pipeline (42), which has a superior portion (421) with a length that is equivalent to approximately 75% to 98% of the height of the first horizontal chamber (5) and an inferior portion (422) with a length that is equivalent to approximately 45% to 80% of the height of the second horizontal chamber (6).

Abstract: An exhaust gas carrying of an exhaust gas system of a combustion engine fulfills a sound-absorbing function and has an outer shell that comprises at least one sound-absorbing portion. The sound-absorbing portion is provided with micro perforations which have a sound-absorbing effect and through which exhaust gas is directly discharged to an external environment.

Abstract: A plenum with features to disperse acoustic energy in an airflow while maintaining a relatively small pressure drop in the airflow is disclosed. A general structure of the plenum may include a perforated airflow passage surrounded by a substantially large space enclosed between the airflow passage and a plenum. The perforated airflow passage has a perforated wall that may allow the acoustic energy to be dispersed into the substantially large space when flowing through the airflow passage. Acoustic energy dispersing materials may also be disposed in the substantially large space and/or on the perforated wall to help disperse acoustic energy by, for example, absorbing the acoustic energy. The plenum can help disperse the acoustic energy while helping minimize the pressure drop in the airflow.

Abstract: A dampening device of the present invention is configured to attenuate acoustic energy produced by a fluid circulating through a fluid system. The dampening device includes a hollow tubular body having a first end, a second end, and a collar interposed between the first end and the second end. The tubular body is disposed within at least one conduit of the fluid system, forming a space between an inner surface of the conduit and the first end of the tubular body and another space between the inner surface of the conduit and the second end of the tubular body.

Abstract: An exhaust system for an internal combustion engine having a first exhaust tract assigned to a first group of cylinders of the internal combustion engine, and a second exhaust tract assigned to a second group of cylinders of the internal combustion engine, the first exhaust tract and the second exhaust tract being coupled to one another by a connecting line. A common bypass line branches off from the connecting line coupling the exhaust tracts.

Abstract: A muffler having a shell of a double-layer structure includes an inner shell that is formed by fixing ends of a tubularly rolled plate material to each other through a lock seam, and an outer shell that is formed substantially in the same manner as the inner shell. In this muffler, a through-hole is provided through the inner shell at a position where the inner shell overlaps with a lock seam portion of the outer shell.

Abstract: A muffler assembly for a vehicle includes a muffler and one of a mount structure and a mount bracket, which is attached to the muffler. Vehicles that include muffler assemblies are also described herein.

Abstract: A muffler for a vehicle exhaust system includes a first outer shell, a second outer shell that cooperates with the first outer shell to define a muffler interior cavity, and at least one porous partition that separates the muffler interior cavity into at least first and second sub-cavities. In one example, the porous partition is integrally molded with at least one of the first and second outer shells. In one example, an exhaust tube extends through the first sub-cavity and acoustic fiber material is located within the first sub-cavity.

Abstract: The present invention relates to a housing (1) with a jacket (2), enclosing a housing interior space (7) in circumferential direction (8). For reducing self-induced vibrations of the jacket (2), at least one preloading device (14) is proposed, which is arranged in the housing interior space (7), which supports itself on a first supporting region (15) of the jacket (2) on the inside of the jacket (2) subject to a first preload (16) orientated towards the outside and which supports itself on a second supporting region (17) of the jacket (2) spaced from the first supporting region (15) on the jacket (2) on the inside subject to a second preload (18) orientated towards the outside.

Abstract: An acoustically dampened gas turbine engine having a combustor with an acoustic damping system is disclosed. The acoustic damping system may be formed from an acoustic damping body having at least one orifice configured to receive a combustor nozzle assembly. The acoustic damping body may be positioned in a head region of a combustor basket and may include one or more orifices in the acoustic damping body. The acoustic damping system may mitigate longitudinal mode dynamics thereby increasing an engine operating envelope and decreasing emissions.

Abstract: An exhaust system (1) for an internal combustion engine, in particular of a motor vehicle, has at least one exhaust tract (2), which has at least one exhaust pipe (3) which conducts exhaust gas, and has at least one active silencer (5). The active silencer (5) has a silencer housing (6) and at least one electro-acoustic converter (7) which is arranged in the silencer housing (6) and at least one connection pipe (8), which connects the silencer housing (6) fluidically to the exhaust pipe (3). The thermal loading of the converter (7) is reduced with a sound propagation path (9) formed for the propagation of airborne noise in the connection pipe (8) being impermeable to thermal radiation (16) emanating from the exhaust gas in the exhaust pipe (3).

Abstract: An exhaust system includes a muffler, an inlet pipe, and an exhaust pipe. The muffler includes an inlet hole adapted to receive the inlet pipe and an outlet hole to receive the exhaust pipe. The inlet pipe has a first and second linear portions extending from a radiused portion, the first and second linear portions being generally perpendicular to one another. The radiused portion and the first linear portion of the inlet pipe are positioned within the muffler. Portions of the inlet pipe and exhaust pipe located within the muffler may optionally include perforations and be closed off.

Abstract: A vehicle exhaust system includes an exhaust component having an inlet and an outlet. The exhaust component is configured to be fixed to a vehicle body. A pipe extends through the exhaust component from the inlet to the outlet. The pipe is mounted for movement relative to the exhaust component at the inlet and the outlet.

Abstract: A first aspect of the present application relates to a method for producing sound-damping, sound-absorbing and/or insulating molded material. More specifically, the method according to the invention relates to a method for producing said molded materials, wherein the fibrous material is wound around at least two carriers and subsequently the wound blank thus obtained remains on the carriers so as to be permanently solidified in order to obtain the molded material according to the invention. A further aspect of the present application concerns the molded material thus obtained, in particular in the form of molded mats or molded objects. Said molded material can be used, in particular, in mufflers. Finally, the following application concerns a device for producing said molded materials from fibrous material.

Abstract: An exhaust muffler for silencing exhaust gases, introduced from a first side, and then discharging them to a second side opposite to the first side, includes a silencing chamber forming structure having first, second and third chambers disposed sequentially from the second side to the first side, an inlet tube to communicate the outside on the first side with the first chamber after having sequentially passed through the third and second chambers, an outlet tube to communicate the second chamber with the outside on the second side after having passed through the first chamber, a first communicating passage communicating between the first and second chambers, and a second communicating passage communicating between the second and third chambers. A peripheral wall portion of the inlet tube, positioned in the third chamber, is formed with a vent hole to communicate a space within the inlet tube with the third chamber.

Abstract: An exhaust muffler includes a pair of base members disposed substantially parallel to one another and defining an exhaust entry and exhaust exit. At least one wall member is coupled to the base members. The at least one wall member is intermediate the base members and intermediate the entry and exit. The at least one wall member includes a linear portion coupled to a semicircular portion.

Abstract: A muffler for a vehicle may include a main muffler in front of a rear suspension when viewing from a front of the vehicle, a plurality of baffles dividing an interior of the main muffler into a plurality of chambers, an inlet pipe installed substantially at an center of one side of the main muffler and passing through the plurality of the baffles, a discharge pipe installed at a lower side of the other side of the main muffler and passing through the plurality of the baffles, wherein the discharge pipe exhausts an exhaust gas flowed in the inlet pipe to an exterior of the main muffler, an intermediate pipe in fluidic communication with an outlet port of the inlet pipe, and a variable valve selectively opened or closed in response to a back pressure of the exhaust gas from an outlet port of the intermediate pipe.

Abstract: A liner assembly for an aircraft engine housing includes a noise attenuation structure that is covered by a face sheet. The face sheet covering the noise attenuation structure includes a surface having a plurality of circumferentially spaced apart acoustic energy absorption areas that are interspersed between a corresponding plurality of acoustic energy reflective areas. The acoustic energy reflective areas scatter higher order acoustic modes into a plurality of lower order modes. The difficult to attenuate lower order acoustic modes produced by the various acoustic energy cancel each other out to provide significant improvement in liner noise reduction efficiency.

Abstract: A system for improved exhaust evacuation from an internal combustion engine made up of a core which is surrounded by an outer casing, an elongated tube, and a perforated chamber made up of two cup shaped portions. The first cup shaped portion is connected to an outlet tube and the second cup shaped portion is connected to the elongated tube. The second cup shaped portion has holes around the connection and the first cup shape portion does not.

Abstract: A muffler system can include an exhaust pipe configured to be connected to an exhaust port of an engine, and a muffler containing a catalyst. The muffler is configured to be connected to a downstream side of the exhaust pipe, and can include a first protector stay covering an upper surface of a high-temperature portion of the muffler. The first protector stay creates a front opening and a rear opening between an upper surface of the muffler and front and rear portions of the protector stay. A muffler protector is attached to the protector stay, the muffler protector being configured to cover an upper surface of the muffler.

Abstract: A sound attenuating heat exchanger for an internal combustion engine includes a housing, a barrier wall and a fin. The housing includes an exhaust inlet, an exhaust outlet, a coolant inlet and a coolant outlet. The exhaust inlet is connected to the exhaust outlet by an exhaust flow passage. The coolant inlet is connected to the coolant outlet by a coolant flow passage. The barrier wall fluidly separates the exhaust flow passage from the coolant flow passage. The fin extends from the barrier wall into the exhaust flow passage, and includes a resonator adapted to attenuate sound waves traveling through exhaust gas within the exhaust flow passage. The barrier wall and the fins are adapted to exchange heat energy between the exhaust gas flowing through the exhaust flow passage and coolant flowing through the coolant flow passage.

Abstract: A horizontally installed muffler may include a housing, first and second tail pipes installed to front and rear ends of the housing through the housing, an introduction chamber formed inside the housing and to which an outlet of the exhaust pipe is connected, a first intermediate pipe fluid-connected to the introduction chamber and having a first discharge hole, a discharge chamber fluid-connected to the introduction chamber through the first discharge hole of the first intermediate pipe, wherein each end of the first and second tail pipes and the first discharge hole are disposed inside the discharge chamber, first and second resonance chambers formed inside the housing, a second intermediate pipe fluid-connected to the first and second resonance chambers through the discharge chamber and the introduction chamber and having an introduction hole disposed inside the introduction chamber and a second discharge hole disposed inside the discharge chamber.

Abstract: Some example muffling devices may include an inner flow conditioner shaped as a generally conical frustrum and a generally cylindrical an exhaust can around the inner flow conditioner. A ratio of a downstream end wall area of the inner flow conditioner to a downstream end annular area between the downstream end wall and the exhaust can may be about 0.12 to about 0.97. A ratio of the downstream end annular area to the downstream end wall area may be proportional, by a factor of about 0.8 to about 1.9, to a ratio of an effective area of the inner flow conditioner sidewall holes to an effective area of the inner flow conditioner downstream end wall holes. A ratio of a dissipation distance between the inner flow conditioner downstream end wall and the exhaust screen to the inner flow conditioner downstream end wall hole diameter may be greater than about 10.

Abstract: Some example muffling devices may include an inner flow conditioner shaped as a generally conical frustrum and a generally cylindrical an exhaust can around the inner flow conditioner. A ratio of a downstream end wall area of the inner flow conditioner to a downstream end annular area between the downstream end wall and the exhaust can may be about 0.12 to about 0.97. A ratio of the downstream end annular area to the downstream end wall area may be proportional, by a factor of about 0.8 to about 1.9, to a ratio of an effective area of the inner flow conditioner sidewall holes to an effective area of the inner flow conditioner downstream end wall holes. A ratio of a dissipation distance between the inner flow conditioner downstream end wall and the exhaust screen to the inner flow conditioner downstream end wall hole diameter may be greater than about 10.

Abstract: A silencer for a two-stroke motor of a power tool, including a silencer inlet to which adjoins a flow channel of channel length so that the flow channel can be connected to an outlet of a combustion chamber of the two-stroke motor, whereby the flow channel at the channel end opposite the silencer inlet opens out into a first chamber of depth, between the silencer inlet and the first chamber the flow channel is so flow-beneficially designed, that due to its mass inertia the exhaust gas flowing into the silencer inlet predominantly flows into the first chamber and after filling the first chamber flows back again thereby creating a counterpressure in the direction of the combustion chamber, so that in spite of small geometric dimensions it provides a periodically actin counterpressure on the outlet of the combustion chamber of the two-stroke motor.

Abstract: In order to improve an arrangement of a silencer on a combustion motor, whereby the silencer has a connection piece which with an end area adjoins an outlet in the cylinder of the combustion motor forms a flow connection between a combustion chamber of the combustion motor and the silencer in such a way a disturbance-free flow connection between a combustion chamber in the cylinder and the silencer is made possible, and more particularly to simplify the mounting of a silencer on the cylinder of a combustion motor, the internal diameter of the end area is made larger than the internal diameter of the outlet.

Abstract: A fluid line includes a resonator having an inner part and a blow-molded outer part defining an inner surface. The inner and outer parts are fixedly connected. The inner part is an injection-molded part having first and second radial collars spaced axially apart from each other. The inner part defines a radial circumference with a plurality of orifices formed therein. The inner and outer parts are axially one within the other so that there is no throughflow of secondary air between the first and second radial collars and the inner surface of the outer part. The inner and outer parts have a common end whereat they are airtightly connected to each other. The inner part, the radial collars and the inner surface of the outer part conjointly define two resonant chambers operatively connected to fluid in the fluid line via the orifices.

Abstract: The invention relates to a blower arrangement for gas. The blower arrangement comprises a blower with a blower housing, at least one gas-inlet opening formed in the blower housing and gas-outlet opening, and at least one rotary-driven blower wheel arranged in the blower housing. Furthermore, the blower arrangement has at least one silencer device with at least one gas guiding element, wherein the gas-guiding element comprises a plurality of silencer openings and is designed as a gas guiding pipe. The gas guiding pipe varies its cross section along its longitudinal extension and has a wall, which is designed to be wave-like along the longitudinal extension of the gas guiding pipe. The silencer device also comprises at least one silencer chamber, which is in flow connection with the silencer openings and is arranged at least in sections laterally behind the gas guiding element.

Abstract: A fluid transfer pipe (1) comprising opposed ends (3, 5) adapted to be connected to respective pipework, the pipe (1) comprising a longitudinal axis (9), the transverse cross section of the pipe (1) varying along the length of the pipe such that the distance radially outwardly from the longitudinal axis (9) to the inner wall of the pipe (1) is non linear along at least part of the length of the pipe. A fluid attenuator comprising such a pipe is also disclosed.

Abstract: An exhaust system component (1) of an exhaust system (2) for an internal combustion engine, especially of a motor vehicle has an inner pipe (3) made of metal, which is exposed to exhaust gas during the operation of the exhaust system (2), a housing (4) made of plastic, which encloses a working space (6), and an outer pipe (5) made of metal. The outer pipe (5) is fastened at a first end area (7) to the inner pipe (3) and is rigidly connected at a second end area (9) to the housing (4) and encloses between these end areas (7, 9) an annular space (10) formed radially between the inner pipe (3) and outer pipe (5).