Abstract: A problem to be solved is to provide an exhaust promotion method, an exhaust promotion device, and an exhaust system improvement method for an internal combustion engine capable of further improving the exhaust efficiency by high-speed exhaust of exhaust gas. What is characteristic is that an exhaust gas discharged from the internal combustion engine is expanded in multiple stages repeatedly to reduce a temperature thereof, and thus exhaustion is performed while suppressing a behavior derived from a thermal energy of the exhaust gas.

Abstract: A mixer is mounted in an aircraft. A rear end part of a cylindrical portion of the mixer is divided by a guide vane into a plurality of divided tubular portions. In the plurality of divided tubular portions, a notch nozzle is formed on an outer wall of the cylindrical portion. A plurality of guide holes are formed to extend from the outer wall of the cylindrical portion to a rear end surface of the guide vane.

Abstract: An internal combustion engine exhaust modification system for transforming exhaust emissions from an internal combustion engine into modified exhaust emissions. The exhaust modification system includes a housing extending between inlet and outlet ends thereof. The system also includes an impeller rotatably mounted in the housing, and a filter subassembly downstream from the impeller. The filter subassembly removes part of particulate matter and liquid droplets in the exhaust emissions to transform the exhaust emissions into modified exhaust emissions. The system includes a conduit extending between an inner end thereof positioned to direct cooler air exiting therefrom into the housing toward the filter subassembly, and an outer end thereof. The system also includes a funnel subassembly having a funnel body for directing the cooler air into the outer end of the conduit.

Abstract: A muffler heat protection system for a vehicle includes a muffler heat shield configured to extend circumferentially around a portion of a muffler, the muffler heat shield having a first end and a second end; a heat shield extension secured to the first end of the muffler heat shield; a double wall exhaust pipe including an inner exhaust pipe and an outer covering pipe disposed over the inner exhaust pipe, the outer covering pipe having a first end portion and a second end portion, and the inner exhaust pipe having a first end portion and a second end portion; wherein the second end portion of the outer covering pipe is welded to the muffler at a welded connection seam; and wherein the heat shield extension projects outward from the muffler heat shield over the welded connection seam.

Abstract: A muffler including a double-pipe structure to muffle sounds in two or more frequencies is provided. The muffler includes an inner and outer pipes with a clearance therebetween. The inner pipe includes a first and second outer surfaces, and, at one end, an opening communicating with the outer pipe. The clearance communicates with an exhaust passage via the opening. The second outer surface forms the opening and is situated closer to the center of the inner pipe than the first outer surface is. A space between the inner and outer pipes is closed due to a contact between the first outer surface and an inner-circumferential surface of the outer pipe. A part of the clearance is formed between the first outer surface and the inner-circumferential surface. The outer-circumferential surfaces of the inner pipe include at least one communication hole that communicates the inner pipe with the clearance.

Abstract: A muffler for decreasing the amount of noise of exhaust gases from a combustion engine is fluid connected with an exhaust port of an engine cylinder through an exhaust pipe. The interior of the muffler is divided into a first expansion chamber on the most upstream side, and a second expansion chamber on a downstream side thereof. The exhaust pipe is fluid connected with the muffler so as to be present within the first expansion chamber. The muffler is furthermore provided with a cooling pipe, which extends through the first expansion chamber, and a cooling air flows through cooling pipe.

Abstract: The present application provides a fire prevention shield for an internal combustion engine. The shield includes a shield baffle plate and a mounting means adapted to mount the shield baffle plate at a predetermined position with respect to a muffler of the engine, such that an air passage is located between the muffler and the shield baffle plate, the air passage having an air inlet opening located adjacent to the engine, wherein a cross-sectional area of the air passage is greatest at or near the air inlet opening.

Abstract: The present invention provides an exhaustion pipe in the mechanical field. The exhaustion pipe of the invention comprises a casing, on the sidewall of which a plurality of ventilation through holes are provided; and a cooling pipe mounted within the housing, which includes a heat dissipative air inlet end and a heat dissipative air outlet end, and on the sidewall of which a plurality of heart dissipative ventilation holes are provided. The exhaustion pipe has advantages including a simple structure, a rapid cooling effect and good safety performance.

Abstract: A muffler for exhaust gases of a combustion engine includes walls forming a chamber through which the exhaust gases pass, a first inlet in the walls of the chamber configured to receive the exhaust gases from an exhaust duct of the engine, a first outlet in the walls of the chamber through which the exhaust gases exit the chamber, and a conduit having a second inlet and a second outlet, wherein a substantial length of the conduit is positioned within the chamber.

Abstract: A cover for the upper end of an exhaust stack pipe comprises a curved cover pipe of greater diameter than the stack pipe. The curved cover pipe has a proximal end to fit over the end of the stack pipe and a distal end from which exhaust gases are discharged. The cover pipe is shaped to prevent rain from falling directly onto the end of the stack pipe. A flow diverter of lesser diameter than the cover pipe is mounted within the proximal end of the cover pipe to overlie the end of the stack pipe. The flow diverter comprises an extension tube for mounting onto the end of the stack pipe having lateral openings and a tapering deflector extending into the extension tube to divert exhaust gases to flow into the cover pipe through the lateral openings in the extension tube.

Abstract: A muffler for a combustion engine includes walls forming a chamber, a first inlet, a first outlet, and a conduit. The first inlet is designed to receive exhaust gases from an exhaust duct of the engine. The exhaust gases pass through the chamber when moving from the first inlet to the first outlet. The exhaust gases then exit the muffler through the first outlet. The conduit extends between a second inlet and a second outlet. The second inlet is configured to receive fresh air entering the muffler. The fresh air then exits the conduit and is introduced into the exhaust gases through the second outlet.

Abstract: A tube comprises a series of guides with each successive guide smaller than a next prior guide forms an effective funnel with a smaller end extending toward into a larger end of a next adjacent guide. The larger end of the next adjacent guide extends past the smaller end of that prior guide and loops back to taper into smooth connection to the outside of the smaller end of that prior guide therein creating a cavity in the guide. Gas passing rapidly past the cavities causes a Bernoulli effect that reduces pressure within the cavities. Because the mouth of the guides is large, a vortex is induced from a shearing interface between gases within the cavity and the main flow of gas moving down the tube. A less energetic layer of gas is created that buffers tube guides from main gas flow through the tube center.

Abstract: An absorptive muffler assembly includes a first body and a second body surrounding the first body. A resilient mount having at least one resilient portion and at least one support arm supports the first body and isolates the second body from vibrations of the first body.

Abstract: A catalytic muffler that treats the exhaust gases of an internal combustion engine. The catalytic muffler includes a catalyst chamber, a catalyst disposed in the catalyst chamber, an upstream chamber disposed upstream of the catalyst, an exhaust inlet configured to receive exhaust gases, an exhaust outlet configured to discharge converted gases converted by the catalyst to the atmosphere, and further configured to receive secondary air, and a passageway communicating between the exhaust outlet and the upstream chamber, and configured to provide the secondary air received by the exhaust outlet to the upstream chamber.

Abstract: An exhaust gas-cooling device for use on an exhaust gas conveyance system of a vehicle having an exhaust gas passageway to emit exhaust gases from an engine to an outlet includes an exhaust passageway pipe in fluid communication with the engine, and a micro-venturi mixing chamber pipe in fluid communication with and located downstream of the exhaust passageway pipe. The micro-venturi mixing chamber pipe defines the outlet of the exhaust gas-cooling device and has at least one aperture disposed on a pipe body of the micro-venturi mixing chamber for introducing ambient air into the micro-venturi mixing chamber pipe.

Abstract: A flow diffuser for vehicles of the type having an engine and an exhaust pipe generally includes a substantially tubular body having an outer surface and a first end configured for attachment to an exhaust pipe. The flow diffuser further includes a diffusion portion including at least one channel having a root end located near the outer surface, an exit port, and a channel axis extending between the root end and the exit port, the channel increasing in flow area along the channel axis to reduce exhaust gas velocity.

Abstract: A fairing is configured for use with the exhaust stack of a heavy-duty vehicle. The exhaust stack has an exhaust pipe with an intake end for receiving exhaust gases from an internal combustion engine and a discharge end for discharging the exhaust gases. The fairing includes a streamlined exterior surface and a cavity for receiving the discharge end of the exhaust pipe. An aperture extends through a rear portion of the exterior surface so that exhaust gases discharged from the discharge end of the exhaust pipe pass through the cavity and out of the aperture. The fairing further includes a coupler to couple the fairing to the exhaust pipe.

Abstract: A passive secondary air muffler for a small internal combustion engine. The secondary air muffler may include a venturi device and a catalytic converter. The venturi device may be in the form of a stamped sheet metal insert which, along with the outer muffler housing or shell, forms a secondary or auxiliary air intake device. The venturi device may also be formed from baffles separating an inlet chamber from an outlet chamber of the muffler. The secondary air intake device provides auxiliary or secondary air to the exhaust gas stream exiting the engine upstream of the catalytic converter to improve the efficiency of the catalytic converter. In an exemplary embodiment, the venturi device has a hemispherical cross-sectional shape or a circular cross-sectional shape taken along a plane substantially perpendicular to the direction of flow of the exhaust gas stream.

Abstract: A vehicular exhaust resonator features an exhaust inlet conduit which narrows down in a manner such as to define a venturi effect region. Air entrainment apertures in the housing of the resonator provide fluid communication between outside cooling air and an air inlet chamber in the resonator. A further air inlet aperture in an outlet conduit section of the resonator is in fluid communication with the air inlet chamber. Due to the venturi effect inside the inlet conduit, a pressure drop is created to pull air from the outside into the air inlet chamber and then into an outlet conduit of the resonator for mixing with the exhaust gas to provide cooling thereof.

Abstract: A resilient mount useful in a muffler assembly includes a support arm, a bracket arm and at least one resilient portion. In one example, the resilient portion comprises neoprene to provide a cushion between the support arm and the bracket arm. The resilient mount is for supporting at least one absorptive body within a housing and isolating the housing from vibrations of the absorptive body.

Abstract: A tailpipe for use with a vehicle moveable in a forward direction upon a support surface and adapted to be oriented substantially perpendicular to the support surface. The tailpipe includes a windward surface facing in the forward direction and a leeward surface facing opposite the forward direction. The tailpipe also includes a tubular body defining a main exhaust gas flow passageway adapted to direct an exhaust gas flow from a proximal end to a distal end of the tubular body and a plurality of exhaust ports. The exhaust ports are disposed between the proximal end and the distal end of the tubular body and pass through the leeward surface for permitting at least a portion of the exhaust gas flow, when present in the tubular body, to exit the tubular body through the plurality of exhaust ports.

Abstract: In an acoustic fluid machine, an acoustic resonator gradually reduces in diameter towards the top on which a valve device is provided to suck a gas into the resonator. The gas is compressed in the resonator by a circular-plate piston at the lower end of the resonator and discharged via an outlet of the valve device. The piston comprises a rubber plate fixed to the resonator and a metal plate attached on the rubber plate.

Abstract: In an acoustic resonator, an actuator allows a piston to reciprocate axially at very small amplitude at high speed. Owing to pressure fluctuation in the acoustic resonator involved by reciprocal motion of the piston, fluid is sucked into and discharged from the acoustic resonator via a valve device at the top end of the acoustic resonator. The acoustic resonator is covered with a gas guide with a space. The valve device is cooled by a fan at the top end of the gas guide.

Abstract: A piston is reciprocated axially at high speed at very small amplitude by an actuator in the larger-diameter base of an acoustic resonator. According to pressure fluctuation in the acoustic resonator involved by reciprocal motion of the piston, fluid is sucked into and discharged from the acoustic resonator via a valve device at the top end of the acoustic resonator. The acoustic resonator is contained in a gas guide. Fluid from the valve device is introduced into the gas guide to cool the valve device.

Abstract: The invention concerns a suction muffler for a hermetic refrigerant compressor with a housing having an inlet and an outlet and limiting at least one muffling chamber, and a gas supply channel located in the muffling chamber between the inlet and the outlet. It is endeavoured to prevent too much oil from remaining in the refrigerant gas flow. For this purpose, the gas supply channel forms a throttling path and ends in the muffling chamber, and that in the area of the inlet of the gas supply channel an oil extraction opening is located, which ends in the muffling chamber.

Abstract: An acoustic fluid machine includes an acoustic resonator, a valve device, a piston, and an actuator. The acoustic resonator has a larger-diameter base and a smaller-diameter upper end. The valve device is provided on the upper end of the acoustic resonator and has a sucking hole and a discharge hole. The piston is provided in the base of the acoustic resonator and has a surface such that the distance between the upper end of the acoustic resonator and the upper surface of the piston is substantially constant over the whole surface of the piston. The actuator is connected to the piston and reciprocates the piston at high speed axially with a very small amplitude so that a gas is sucked into the acoustic resonator via the sucking hole and discharged via the discharge hole by virtue of pressure fluctuations within the acoustic resonator.

Abstract: In an acoustic fluid machine, an acoustic resonator gradually reduces in diameter towards the top on which a valve device is provided to suck a gas into the resonator. The gas is compressed in the resonator by a circular-plate piston at the lower end of the resonator and discharged via an outlet of the valve device. The piston comprises a rubber plate fixed to the resonator and a metal plate attached on the rubber plate.

Abstract: An acoustic fluid machine such as an air compressor comprises an acoustic resonator, a valve device and a piston. Air is sucked into the resonator through the valve device at one end of the resonator. The piston at the other end of the resonator is reciprocated by an actuator to compress the air in the resonator to cause resonance to increase pressure of the air significantly. The inner surface of the resonator is suitably curved to comply with the formula of a half-period cosine function.

Abstract: A suction muffler for a reciprocating hermetic compressor, comprising a hollow body (10) provided with a gas inlet and a gas outlet (12, 14), which are respectively in fluid communication with the gas supply to the compressor and with a suction side thereof, said hollow body (10) defining a plurality of chambers comprising an innermost first acoustic chamber (50) in fluid communication with the gas outlet (14) of the hollow body (10), and a second acoustic chamber (51) surrounding at least partially the first acoustic chamber (50) and in fluid communication with at least one of the parts defined by said first acoustic chamber (50) and by the gas inlet (12) of the hollow body (10).

Abstract: The invention concerns a suction muffler for a refrigerating machine with a housing, in which at least one chamber is arranged and which has an inlet opening (7), an outlet opening and an oil discharge opening. It is endeavoured to avoid that too much oil remains in the chamber. For this purpose, an oil collecting room is arranged to be connected to the bottom end of the chamber, the oil discharge opening being arranged at the bottom end of said oil collecting room.

Abstract: A noise reduction system for significantly reducing the noise generated by an air turbine used to create suction for automatic cutting tables. The system employs one or more baffles mounted within a closed main housing including noise reduction foam and an exhaust housing lined with noise reduction foam mounted around the baffle exhaust. The direction of the exhaust air is changed 180 degrees and is utilized for cooling the air turbine and electric motor.

Abstract: The invention relates to a suction muffler for a hermetically enclosed compressor, with a housing having a first part with an outlet channel and a second part with an inlet channel, flow conducting means being arranged between the outlet channel and the inlet channel, said means forming, together with the inlet channel and the outlet channel, a flow path, and a filter being arranged in the outlet channel. Further improvements of the noise damping are endeavored. For this purpose, the filter has a sieve-like embodiment and that the flow path comprises at least one second filter with a sieve-like embodiment.

Abstract: A suction muffler in a reciprocating compressor is installed over a suction valve to attenuate complex sound pressure (noise) such as vibrational noise, valve sonance, flowing noise and pulsative noise produced from the suction valve when low temperature, low pressure refrigerant gas ejected from an evaporator is sucked into a cylinder via the suction valve and a suction portion of the cylinder. A Tesla valve having two distribution paths is mounted in the suction muffler to attenuate the complex sound pressure (noise) while preventing the reflow of the refrigerant gas into the suction muffler from the suction valve. As a result, the Tesla valve also enhances the cooling ability of the compressor and the attenuation effect.

Abstract: The invention concerns a suction muffler for a refrigerating machine with a housing, in which at least one chamber is arranged and which has an inlet opening (7), an outlet opening and an oil discharge opening.

Abstract: A silencer is disclosed that reduces the acoustic energy of a fluid mixture of a liquid coolant and of exhaust gas from an engine. The engine may be a marine engine. The silencer according to this aspect includes a receiving chamber that receives the fluid mixture and exhaust gas, at least one lifting conduit; and a separation chamber. The lifting conduit has a receiving portion with a first opening and an expelling portion with a second opening. The receiving portion is fluidly coupled with the receiving chamber so that the fluid mixture enters the first opening from the receiving chamber and is lifted through the lifting conduit to the expelling portion. This lifting may be accomplished, at least in part, by dynamic effects. The separation chamber is fluidly coupled with the second opening of the lifting conduit, and has at least one interior surface.

Abstract: The invention relates to a suction muffler in a reciprocating compressor. The suction muffler is installed over a suction valve in order to attenuate complex sound pressure (noise) such as vibrational noise, valve sonance and flowing noise and pulsative noise which is produced from the suction valve when refrigerant gas in low temperature and pressure ejected from an evaporator is sucked into a cylinder via the suction valve and a suction portion of the cylinder. Further, a Tesla valve having the two distribution paths is mounted within the suction muffler in order to attenuate the complex sound pressure (noise) such as vibrational noise, valve sonance and flowing noise and pulsative noise produced from the suction valve while prevent the reflow of the refrigerant gas into the suction muffler from the suction valve.

Abstract: The invention concerns an arrangement for a discharge system for combustion gases from a motor-driven vehicle which gives the vehicle a low IR signature. According to the invention, the gas outflow channel (28), at least in an area of the channel adjacent to the discharge aperture (32), has a boundary wall (34) which is perforated right up to the open discharge aperture (32) and surrounded by a cooling air channel (38). The arrangement is such that cooling air can sweep over the inner side as well as the outer side of the perforated wall (34).

Abstract: A muffler for an internal combustion engine has a vertically elongated expansion chamber into which an exhaust gas from the exhaust port of internal combustion engine is introduced. The expansion chamber is separated level-wise into a first expansion chamber and a second expansion chamber by a partition plate. An exhaust emission purifier formed of an oxidation catalyst is attached to the partition plate, thereby allowing the exhaust gas ejected from the exhaust port to be introduced into the second expansion chamber from the first expansion chamber via the exhaust emission purifier. The exhaust emission purifier is spaced apart from the exhaust port by a predetermined distance in a direction orthogonal to an ejecting direction of the exhaust gas.

Abstract: The present invention relates to a muffler used in a motor vehicle for cooling the engine exhaust gases. The muffler has an internal tubular member defining an internal chamber and a middle tubular member concentric in relation to and supported on the internal tubular member. The internal and middle tubular members form a first ring-shaped chamber adapted to connect to the exhaust pipe. The muffler also has an external tubular member being concentric in relation to and supported on the middle tubular member. The middle tubular member and the external tubular member form a second ring-shaped chamber with a third inlet portion. Hence, engine exhaust gases of the motor vehicle pass through the first ring-shaped chamber and are sufficiently cooled and depressurized by cooling air that passes through the internal and second ring-shaped chambers.

Abstract: A muffler for a two-stroke internal combustion engine includes an expansion chamber into which exhaust gas ejected from the exhaust port of the engine is introduced. An air-supplying device is adapted to supply outside air to the expansion chamber. The air-supplying device is actuated by taking advantage of the pressure pulsation in the crank case of the engine, and is constituted by a diaphragm pump.

Abstract: An exhaust apparatus for an engine is provided, which is capable of efficiently sucking in secondary air for a catalyst by utilizing an ejector (entraining) effect caused by the exhaust gases and which has a simple and inexpensive structure. Exhaust gases from the engine are introduced into a main muffler body, are expanded and muffled by passage through a plurality of silencer chambers, and are also passed through a catalyst and scrubbed thereby in a state in which they are mixed with secondary air introduced from the exterior. A secondary air introduction pipe for introducing secondary air is provided in a first-stage silencer chamber. A mixing pipe is provided into which are introduced the secondary air introduced from the secondary air introduction pipe and the exhaust gases from the first-stage silencer chamber.

Abstract: A muffler for an internal combustion engine has an expansion chamber (31, 32) into which exhaust gas from the engine is introduced. The expansion chamber has a double wall (32A), with an inner panel (42) of the double wall (32A) having exhaust gas discharge portions (42A, 42B, 42C, 42D) with respective blowout holes (61, 62, 63, 64) for introducing the exhaust gas from the expansion chamber (32) into an air space (Sb) in the double wall (32A). From the air space (Sb), the exhaust gas is vented to the ambient through a discharge hole (37A) in an outer panel (42) of the double wall (32A ). A spark arrester screen (72) covers the discharge hole (37A).

Abstract: A muffler for a two-stroke internal combustion engine has an expansion chamber into which a rush of exhaust gas is introduced from the engine. In the vicinity of an exhaust gas inlet from the engine into the expansion chamber, the muffler has an external air intake for external air to be suctionally introduced into the expansion chamber by the rush of exhaust gas. With the external air introduced, carbon monoxide (CO) emission into the ambient is reduced.

Abstract: An engine exhaust apparatus comprises a sound suppressing section for lowering the exhaust noise level as an exhaust gas discharged from the exhaust port passes through it. The exhaust apparatus is provided with an ejector section for introducing secondary air into the exhaust gas delivered from the sound suppressing section and mixing the gases, and a post-treatment section for purifying the gas mixture delivered from the ejector section. The exhaust gas discharged from an exhaust manifold gets into the ejector section through the sound suppressing section, and is then purified in the post-treatment section. Therefore, the ejector effect cannot be reduced by the sound suppressing section which is subject to high flow resistance. Thus, the exhaust noise level can be lowered with the ejector effect of the introduction of the secondary air improved considerably, and low cost and simple construction can be enjoyed.

Abstract: Methods and apparatuses for muffling steam exhausted from a power plant, in one aspect, the method including flowing the steam into and through a submerged hollow pipe having a plurality of holes spaced apart along it and one or more water eduction tubes through which, due to the effect of the flowing steam, water is sucked into the hollow pipe.

Abstract: An internal combustion engine according to the present invention is comprised of a conduit means that directs the flow of exhaust from an internal combustion engine to a relatively low speed turbine connected to a generator. The conduit means also acts as a mixing means for mixing appreciable quantities of outside air with the exhaust for recombustion prior to entry into the turbine. The turbine is designed to utilize the energy of the recombusted gases through impact and redirection of the gases upon the turbine blades. This invention comprises a dual function conduit means connecting internal combustion engine exhaust to a relatively low speed turbine wherein the conduit means also induces an appreciable flow of outside air to mix with the exhaust gases to effectively lower the temperature of the gases imposed on the turbine but without lowering the total energy of the gases.

Abstract: An exhaust outlet with venturi is disclosed, comprising an upstream portion (18) in the form of a venturi, defined by upstream walls (16) converging at an open angle and connected, in a narrowed portion (15) to downstream walls (17) diverging at a more reduced angle and a cylindrical downstream portion (3) connected continuously to the downstream walls (17) of the upstream portion (18). The presence of the upstream portion in the form of a venturi substantially reduces the backlash noise without substantially affecting the available power of the engine.

Abstract: An elongate exhaust gas muffler for a turbine engine includes a foraminous central exhaust duct which is circumscribed along its length by a plurality of tuned dissipative and reactive noise attenuation chambers. At an inlet end of the muffler an annular secondary flow inlet is defined about the central exhaust duct and opens to the first sound attenuation chamber. A secondary flow of pressurized bleed air is receivable into the first attentuation treatment in the muffler.

Abstract: An improved muffler including a body 2 with an exhaust inlet 3 in the form of a porous pipe enclosed in s second porous pipe 31 for diffusing exhaust gases into the interior of body 2. A pair of pipes 5 introduce ambient air into the discharge region of the muffler. A constricted discharge opening 41 of the body 2 encircles the pipes 5 and confine helical vanes 51 which impart a helical path to the exhaust gases just before mixing with ambient air from the pipes 5. A venturi section 6 with a bell shaped outlet 62 completes the tailpipe section 4. An auxiliary air inlet 43 to the venturi 6 adds additional ambient air to the final outlet via ports 63. In an additional embodiment (FIG. 8), the venturi section 113 is within the muffler body 100. A constricted tube 121 provides a direct path for a portion of the exhaust gases while the major quantity of exhaust gases traverse the helical paths defined by the vanes 123.

Abstract: A water-cooled type internal combustion engine for a farming motor vehicle has a muffler arranged within the space on the lateral side of an engine body disposed in the fore and rear direction of the farming motor vehicle. An exhaust gas dilution pipe is externally fitted at its upper end portion to an outlet pipe of the muffler so as to provide a cooling air passage gap therebetween. The lower end portion of the dilution pipe is extended below the projected end portion of the outlet pipe. A portion of the cooling air delivered by the operation of a radiator fan so as to pass through a radiator is guided by means of a muffler cover so as to be forcedly fed into the dilution pipe through the cooling air passage gap in order to facilitate the dilution of the exhaust gas.