WO1999058824A1 - Silencieux pour debits de gaz - Google Patents

Silencieux pour debits de gaz Download PDF

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Publication number
WO1999058824A1
WO1999058824A1 PCT/FI1999/000417 FI9900417W WO9958824A1 WO 1999058824 A1 WO1999058824 A1 WO 1999058824A1 FI 9900417 W FI9900417 W FI 9900417W WO 9958824 A1 WO9958824 A1 WO 9958824A1
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WO
WIPO (PCT)
Prior art keywords
silencer
channels
flow
flow area
cross sectional
Prior art date
Application number
PCT/FI1999/000417
Other languages
English (en)
Finnish (fi)
Inventor
Tom Erik Jacoby
Original Assignee
Tom Erik Jacoby
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tom Erik Jacoby filed Critical Tom Erik Jacoby
Priority to AU41471/99A priority Critical patent/AU4147199A/en
Publication of WO1999058824A1 publication Critical patent/WO1999058824A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/007—Apparatus used as intake or exhaust silencer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/06—Silencing apparatus characterised by method of silencing by using interference effect
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/0335—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with exhaust silencers in a single housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/033—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices
    • F01N3/035—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters in combination with other devices with catalytic reactors, e.g. catalysed diesel particulate filters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2882—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices
    • F01N3/2885—Catalytic reactors combined or associated with other devices, e.g. exhaust silencers or other exhaust purification devices with exhaust silencers in a single housing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
    • F02M35/12—Intake silencers ; Sound modulation, transmission or amplification
    • F02M35/1205—Flow throttling or guiding
    • F02M35/1227—Flow throttling or guiding by using multiple air intake flow paths, e.g. bypass, honeycomb or pipes opening into an expansion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
    • F02M35/12—Intake silencers ; Sound modulation, transmission or amplification
    • F02M35/1205—Flow throttling or guiding
    • F02M35/1233—Flow throttling or guiding by using expansion chambers in the air intake flow path

Definitions

  • the invention relates to a silencer for the exhaust gas or suction air of a combustion engine or for some other pulsative gas flow, whereby the silencer can be connected between an inlet flow duct having a first cross-sectional flow area and an outlet flow duct having a second cross-sectional flow area, and whereby the silencer comprises a number of individual silencer channels having different lengths and being arranged in parallel regarding the flow, whereby the gases pass through the channels from the inlet flow duct to the outlet flow duct, whereby the total cross-sectional flow area of all silencer channels is not substantially smaller than said first cross- sectional flow area.
  • the invention relates also more generally to a method for at- tenuating the sound of a pulsating gas flow propagating in a channel and discharged to the environment either from the inlet opening or from the outlet opening of the channel.
  • the pressure pulses are typically repeated, for instance when a combustion engine is running or when a compressor is in operation, at rather even intervals as the running speed is kept constant. Normally the strength of the pulses will vary when the load- ing of the machine changes, even if the running speed, such as the speed of rotation of a combustion engine of a compressor, would be kept constant. In most machines and engines there are further made provisions for variations of the running speed, which means that at least the intervals between the pressure pulses often vary in a wide range. In order to facilitate the treatment the pulses appearing at intervals in the piping can be approximated by a closely corresponding frequency, even though the pressure pulses often are asymmetric.
  • the running speeds vary depending on the machine or engine type, for instance between 1000 and 6000 rpm in cars, and between 1500 and 10,000 rpm in motorcycles, whereby the corresponding frequency of the pressure variations in the exhaust gas and the suction air lie in an interval of about 67 to 400 Hz for a four-cylinder engine, and in an interval of about 25 to 167 Hz for a one-cylinder engine, and in an interval of about 50 to 333 Hz for a two- cylinder engine.
  • a problem of silencers is to provide a structure which effectively attenuates the sound caused by such pressure variations both at the lower end of the frequency range, i.e. typically at frequencies 20 to 100 Hz, and at the higher end of the frequency range, i.e.
  • the gas flow can simultaneously contain a plurality of pressure variations at different frequencies, which also must be possible to attenuate.
  • the basic frequencies determined by the speed of rotation pressure pulses also occur at their harmonic frequencies, whose sufficient attenuation is often quite problematic.
  • the frequency range where the attenuation must be possible is substantially widened due to these harmonic frequencies, as compared to the frequency range caused only by the basic frequencies. The above described operation on a wide frequency range is the most common situation. Nery seldom a machine or engine would be used at only one running speed, whereby the attenuation could be designed only regarding this frequency.
  • One attenuation possibility is to direct the gas flow past a material which is porous or non-porous, whereby a part of the flowing medium and at least the pressure fronts of the pulses penetrate into the mass of the attenuating material, where the sound energy is transformed via friction into heat.
  • a material which is porous or non-porous Such a structure is presented in the publication US-4 362 223. Disadvantages of such a silencer of the by-pass type is a poor sound attenuation capability, the short life of the attenuating material for instance due to the pores becoming clogged, and the decreasing elasticity of the attenuating material which will be totally lost in the long run.
  • the DE publication further uses the above mentioned absorption method in order to improve the attenuation.
  • a disadvantage is that it increases the periodical motion forward and backward of the gas flow, i.e. a periodical backward directed flow, and the poor flow characteristics or the relatively high flow resistance.
  • a third alternative is a resonator attenuator, i.e. a Helmholz resonator, which is formed by a channel and a chamber, whereby the entity formed by them has a natu- ral frequency which is as far from the natural frequency of the sound source as possible.
  • a resonator attenuator i.e. a Helmholz resonator, which is formed by a channel and a chamber, whereby the entity formed by them has a natu- ral frequency which is as far from the natural frequency of the sound source as possible.
  • Such resonator silencers are described in the publications EP-0 709 555 and NO-31414. With this arrangement the resonator can be used as a flow-through resonator, and the attenuation functions on a rather wide range, as long as the frequencies to be attenuated substantially differ from the natural frequency of the device, at which a flow-through resonator acts as an amplifier.
  • a fourth alternative is to distribute the incoming flow into channels which have different lengths and which are combined at their other ends, at a position where the pressure difference pulses have different phases due to the propagation paths with different lengths.
  • the publications EP-0 421 724 and GB-2 056 555 describe silenc- ers of this type.
  • the publication EP-0 421 724 describes an arrangement where the cross-sectional flow areas of the inlet duct and the outlet duct are equal, and where, between the inlet and the outlet, the total cross-sectional flow area of the silencer tubes with different lengths is equal to the inlet duct's cross-sectional flow area or slightly larger and equal to the outlet duct's cross-sectional flow area or slightly larger.
  • the length difference of the silencer tubes is not mentioned in the publication, but on the basis of the figures the difference seems to be about 10 %.
  • the publication GB-2 056 555 describes a corresponding structure, where however all tubes are shaped as flat tubes in order to cool the exhaust gas passing through the tubes.
  • a disadvantage of the described solutions is their very large size and weight, particu- larly when attenuation is required on a large frequency range and/or at low frequencies.
  • the large size and weight are due to the fact that the length difference between the silencer tubes must be at least approximately as large as half of the wavelength of the frequency to be attenuated.
  • the wavelength depends on the sum of the sound velocity and the flow velocity, whereby the wavelengths of the above mentioned low frequencies are of the order 17 m (20 Hz), 13.6 m (25 Hz), 6.8 m (50 Hz) and 5 m (67 Hz).
  • the half wavelength, and thus the length difference of the silencer tubes is 8.5 m, 6.8 m, 3.4 m and 2.5 m, respectively.
  • the catalysers are generally arranged in the exhaust pipes, separated from the silencers, and particularly between the main silencer and the engine, rather close to the engine, so that the temperature of the catalyser can be rapidly raised after a start to the operating temperature and kept there, even if a wind with a subzero temperature would cool the device.
  • the publications EP-0 530 493 and DE-34 06 507 propose to use a catalyser also as the silencer of the exhaust gases, whereby the device units on the exhaust gas side would be cheaper and smaller.
  • disadvantages of a silencer built in this way are an occasional backward flow and a high flow resistance.
  • the capability to attenuate the sound is rather poor, particularly in relation to the high flow resistance.
  • the object of the invention is a device and a method for effectively attenuating sound generated by the pressure variations of a gas or similar medium flowing in a space defined by walls, such as in a channel or a tube or a chamber.
  • Another object of the invention is to realise this effective sound attenuation so that the flow resistance caused by the attenuating members is as low as possible, and that backward flow of the gases or periodical backward and forward of the gases should not occur at all, or at most to a very low extent.
  • a third object of the invention is to realise this sound attenuation so that the attenuation is effective also at the frequencies of low pressure variations as well as on the harmonic frequencies.
  • a fourth object of the invention is to realise this effective sound attenuation so that the size and weight of the silencer unit are as small as possible, most preferably so that they are smaller than the size and weight of known silencer units having a corresponding attenuation effect.
  • a fifth object of the invention is to provide a silencer unit which fulfils the above defined requirements and which can be used in the exhaust pipes of combustion engines, in the suction air ducts of combustion engines, in different compressors, as well as in other similar engines and machines, and which when required also could be combined with at catalyser, at the same time at least maintaining both the advantages of the catalyser and the advantages of the silencer.
  • the silencer unit should also be advantageous regarding the manufacturing costs.
  • the silencer according to the invention is characterised in what is presented in the characterising clause of claim 1
  • the sound attenuation method according to the invention is characterised in what is presented in the characterising clause of claim 9.
  • An essential advantage of the invention is that a silencer according to the invention can effectively attenuate also low frequencies, such as the sound from the exhaust gases and/or suction air of combustion engines at normally used speeds of rotation, and at the same time this silencer according to the invention is light-weight and small-sized, whereby it is suitable for mounting for instance at conventional locations in cars, motorcycles and in other working machines.
  • An advantage of the invention is also a low flow resistance, and for instance that the backward flow of the exhaust gases is prevented or very low, which enables an even flow through the silencer without any substantial power losses.
  • a silencer according to the invention has a simple structure, it is easy to mount due to its small size and low weight and due to its adaptable shape.
  • An advantage of the invention is also that a silencer and a catalyser can be effectively combined, whereby according to the in- vention the catalytic members of the catalyser are actually shaped as members realising the attenuation, whereby it provides an effective silencer having good flow resistance properties.
  • the catalytic members can, when required, be arranged according to the invention so that they will be rapidly heated and maintained at a suitable temperature.
  • Figure 1 shows in a side view, in the direction I of figures 2A and 2B, one embodiment of a silencer according to the invention when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes immediately into a mixing chamber which is common to the tubes.
  • Figures 2A and 2B show in cross section two different ways according to the invention to shape the silencer tubes, as applied to the positions of figure 1 and shown along the plane II - II of figure 1.
  • Figure 3 shows in a side view another embodiment of a silencer according to the invention, seen in the same way as in figure 1, when the outer casing of the silencer is removed from the viewing side.
  • Figure 4 shows in a side view a third embodiment of a silencer according to the invention, seen in the direction III of figure 5, when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes immediately into a mixing chamber which is common to the tubes.
  • Figure 5 shows the silencer of figure 4 in a top view, in the direction IN of figure 4, when the outer casing of the silencer is removed from the viewing side.
  • Figure 6 shows in a side view a fourth embodiment of a silencer according to the invention, in the same view as in figure 1, when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes immediately into a mixing chamber which is common to the tubes.
  • Figure 7 shows in a side view a fifth embodiment of a silencer according to the invention, in the same view as in figure 1, when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes immediately into a mixing chamber which is common to the tubes.
  • Figure 8 shows in a side view a sixth embodiment of a silencer according to the invention, in the same view as in figure 1, when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes immediately into a mixing chamber which is common to the tubes.
  • Figure 9 shows in a side view a seventh embodiment of a silencer according to the invention, in the same view as in figure 1 , when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes first to an additional members formed by a catalyser, and then into a mixing chamber which is common to the tubes.
  • Figure 10 shows in a side view an eighth embodiment of a silencer according to the invention, in the same view as in figure 1, when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes first to an additional member formed for instance by a particle filter, and then to a mixing chamber which is common to the tubes.
  • Figure 11 shows in a side view a ninth embodiment of a silencer according to the invention, in the same view as in figure 1, when the outer casing of the silencer is removed from the viewing side.
  • the gases flow from the silencer tubes into a mixing chamber which is substantially formed by the volume of a particle filter or a catalyser and which is common to the silencer tubes.
  • Figure 12 shows in a side view a part of a tenth embodiment of a silencer according to the invention, at the position N of figure 1, when the outer casing of the silencer and also any external casings of the silencer tubes are removed from the viewing side.
  • the gases flow through such silencer tubes which contain catalyser material, and then to a mixing chamber which is common to the tubes.
  • the figures show a silencer according to the invention for a pulsative gas flow, whereby the silencer at one end is connected to the inlet duct 1 or ducts la, lb, and at its other end to the outlet duct 2 or ducts 2a, 2b.
  • the inlet duct 1 has a gas flow FI which is distributed into a plurality of mutually separate silencer channels 3 of different lengths, through which the gas passes as a flow F3.
  • the silencer channels 3 are coupled in parallel. From the silencer channels 3 the gas flow F3 discharges, either immediately or via any additional device into a mixing chamber 4 which is common to all these silencer channels, and in this chamber the gas propagates as the flow F4.
  • the inlet duct has a first cross-sectional flow area Al, which is defined by the wall 20 of the channel, such as a duct.
  • the outlet duct 2 has a second cross- sectional flow area A2, which is defined by the walls in the direction of the flow F2.
  • Said plurality of silencer channels 3 have a total combined cross-sectional flow area A3, which is not substantially smaller than the first cross-sectional flow area Al of the inlet duct 1.
  • the cross-sectional flow area Al of the inlet duct 1 and the cross-sectional flow area A2 of the outlet duct 2 are substantially equally large, but depending on the application of the silencer according to the in- vention they may also have different sizes, or substantially different sizes.
  • the first cross-sectional flow area Al of the inlet duct may be either larger or smaller than the second cross-sectional flow area A2 of the outlet duct.
  • the gas 10 coming as a flow FI in the inlet duct may originate in a combustion engine, whereby the question is about exhaust gases and typically a piston operated combustion engine, whereby there occur pressure pulses in the inlet flow FI caused by the engine's exhaust strokes, and the propagation of these pulses to the outlet duct must be prevented, i.e. they must be attenuated or silenced.
  • the outlet duct 2 discharges either directly into the environment 22, as in figure 8, or it continues as an outlet flow F2 into an extension (not shown in the figures) of the outlet duct, or to some other device not shown in the figures.
  • the outlet duct 2 is connected to the combustion engine, such as for instance on the suction side of a piston engine, whereby there occur pressure pulses in the outlet flow F2 caused by the suction strokes of the engine, and the propagation of these pulses to the inlet flow FI at the inlet duct 1 must be prevented, i.e. attenuated.
  • the silencer according to the invention operates quite as well on the exhaust gas side, where the pressure pulses propagate in the same direction as the flows FI, F3, F4, F2 of the gas 10, as on the suction side of the combustion engine, where the pressure pulses propagate in the opposite direction as the flows FI , F3, F4, F2 of the gas 10.
  • the silencer according to the invention operates also quite as well for attenuating the sound effects of the flow of any flowing medium in which there occurs pressure pulses, so that the invention also relates generally to all such embodiments or applications where the sound effects of pressure pulses in the medium flow must be attenuated or silenced.
  • the medium can also be a liquid.
  • the invention relates particularly to the attenuation of the sound effects of pressure pulses contained in gases, gas mixtures and steam containing gases and steam mixtures.
  • a particular feature of the invention is thus the above mentioned mixing chamber 4 which is located between the outlet openings 5 of the silencer channels 3 and the inlet openings 6 of the outlet duct 2.
  • the silencer channels 3 generally discharge immediately into the mixing chamber 4 which is common to the silencer channels, whereby the cross-sectional flow area A4 in this chamber is substantially larger than the total combined cross-sectional flow area A3 of the si- lencer channels 3.
  • the recombination of the flows F3 occurring immediately after the silencer channels 3 is very advantageous.
  • the total cross-sectional flow area A4 regarding the flow F4 in the mixing chamber is substantially larger than the total combined cross-sectional flow area A3 of the silencer channels 3 regarding the flow F3.
  • the cross-sectional flow area A4 in the mixing chamber is at least two times, preferably four times, and typically ten times or more times the total combined cross-sectional flow area A3 in the silencer channels.
  • the lengths L2, more particularly the lengths L2 ! ... L2 n , of the silencer channels 3 are different, as can be seen in the figures, the sub-flows of the flow F3 branched into these silencer channels 3 have phase shifts regarding the pressure pulses when they are discharged from the outlet openings 5 of the silencer channels 3.
  • the efficiency of the attenuation in the silencer and the method according to the invention is based on the following phenomenon.
  • Half of this wavelength ⁇ /2 is that factor which determines the length difference of the silencer tubes according to the prior art and described in the general part of this application.
  • the mixing chamber 4 according to the invention considerably shortens the silencer channels 3, compared to the lengths of the prior art silencer channels 3 at the same lowest frequency ⁇ to be attenuated.
  • the silencer channels are shortened to one tenth, if the ratio A4/A3 of the cross-sectional flow areas is twenty, the silencer channels are shortened to one twentieth, and if the ratio A4/A3 of the cross-sectional flow areas is thirty, then silencer channels 3 are shortened to one thirtieth.
  • Ratios A4/A3 of the cross-sectional flow areas of this order can in practice be achieved easily, even when the outer dimensions of a silencer according to the invention are of the same order as the outer dimensions of any currently used silencer.
  • the silencer and the silencing method according to the invention are very efficient and small-sized, irrespective of whether the velocity determining the wavelength of the pressure pulses is the sound velocity, the flow velocity, or their combination.
  • the length of the silencer channels 3 and thus the size of the whole silencer is substantially smaller than that of any known silencer with the same effect.
  • the shortening of the silencer channels 3 to the above mentioned fraction also substantially reduces their flow resistance, as is understandable.
  • the mixing chamber 4 seems to eliminate, in at least some degree, the effect of the sound velocity on the wavelength, whereby in a solution according to this invention the flow velocity of the gas 10 would act as a factor determining only the effective wavelength ⁇ of the pressure pulses, or as a factor which is substantially significant in forming the effective wavelength ⁇ .
  • This effect further shortens the length L2 of the silencer channels 3 by at least one or two orders, or to one tenth or one hundredth, compared to the silencer channel lengths required by prior art solutions.
  • silencer channels having a very reasonable length having a length difference ⁇ L2 of the order of less than one metre, perhaps half a meter or 20 cm, can almost completely attenuate pressure pulses with a frequency below 30 Hz. If the lowest frequency to be attenuated is higher, for instance 100 Hz, an effective attenuation can be obtained already with a length difference ⁇ L2 of the silencer tubes 3 of only a few centimetres.
  • the cross-sectional flow area A4 of the mixing chamber 4 is continuous and undivided, such as shown in the figures. It is of course possible to arrange plates, blades or similar in the mixing chamber for directing the flow F4, but however, according to the present understanding this is not advantageous. Further there is a distance LI between the outlet openings 5 of the silencer channels and that opposite wall 7 of the mixing chamber 4, which is closest to said outlet openings 5 in the main direction of the gas flow F3 discharging from the silencer channels into the mixing chamber.
  • This distance LI is preferably larger than the smallest cross-section Wl of the silencer channels 3.
  • the object of this dimensioning is to prevent the flow F3, as it is discharged from the outlet openings 5 of the silencer channels, to hit a solid surface too early, which could reflect the pressure pulse, and which could prevent a rapid reduction of the flow velocity N3 to the flow velocity N4 prevailing in the mixing chamber.
  • an inlet opening 6 of the outlet duct 2 in such a position of the wall of the mixing chamber that the second cross-sectional flow area A2 of the out- let duct 2 is located at least partly elsewhere or in some other place than in the area defined by the extensions of the silencer channels 3 or in the area defined by the extension of the main direction of the gas flow F3 discharging from the silencer channels 3.
  • the purpose of this is to prevent the gas flow F3 discharged from the silencer channels to continue, due to the inertial forces, directly into the outlet duct, which would impair the retardation in the mixing chamber 4.
  • the inlet openings 11 of the downstream silencer channels 3b form at the same time the opposite wall 7 and the inlet opening of a virtual outlet duct for the first silencer channels 3a.
  • the inlet openings 11 of the downstream silencer channels 3b are partly located in the region of the outlet openings of the first silencer channels 3 a and partly outside them.
  • the outlet openings 5 of the second silencer channels 3b are also located partly in the region of the outlet ducts 2a and 2b, of which there are two in this case, and partly outside them.
  • the inlet opening 6 of a single outlet duct 2 is located wholly outside the are defined by outlet openings 5 of the silencer channels 3.
  • the frequencies ⁇ of the pressure difference pulses of said pulsative gas flow FI or correspondingly F2 will vary during the operation of the engine of machine.
  • a particular silencer must attenuate pressure difference pulses occurring at different frequencies, and often on a quite wide frequency range.
  • the attenuation can be realised by arranging in a silencer according to the invention at least five silencer channels 3 and preferably at least ten silencer channels 3.
  • the lengths L2 ⁇ ... L2 n of the individual silencer channels 3 are arranged to be distributed, either at even intervals or according to a predetermined function between the shortest si- lencer channel with the length L2] . and the longest silencer channel with the length L2 n .
  • the silencer and correspondingly the method according to the invention can be made to operate so that they attenuate the sound caused by pressure pulses over a desired frequency range.
  • L2 n of the silencer channels, the length difference ⁇ L2, and the cross- sectional flow area A4 in the mixing chamber 4, and the total cross-sectional flow area A3 of the silencer channels 3, and then of course also their ratio A4/A3, are defined in advance to suit the particular application of the silencer, i.a. on the basis of the frequencies ⁇ to be attenuated.
  • the flow FI in the inlet duct 1 is advantageous to arrange to be evenly distributed and without any substantial velocity changes from the first cross-sectional flow area Al to the combined cross-sectional flow area A3 of the silencer channels 3.
  • This can be arranged with the aid of a flow distributi- on chamber 8 described below.
  • the cross-sectional flow area A3 of the silencer channels and the first cross-sectional flow area Al of the inlet duct preferably differ at most 30 %, and if possible, at most 15 % from each other.
  • the combined cross-sectional flow area A3 in the silencer channels and the first cross-sectional flow area Al can of course be equally large.
  • the outlet flow F2 from the mixing chamber 4 can be arranged through the second cross-sectional flow area A2' or A2 or A2" of the outlet opening 6, which is either as large as the largest cross-sectional flow area A4 of the mixing chamber 4, such as in figure 8, or smaller than the largest cross-sectional flow area A4 of the mixing chamber.
  • the mixing chamber 4 has a free connection to the environment 22 or an almost free connection to the environment 22, as in figure 8, or via an outlet duct 2 with a more restricted cross-sectional flow area to the environment 22 or to some other device not shown in the figures.
  • Figure 1 shows an advantageous embodiment of the invention where the gases 10 are supplied through the flow distribution chamber 8 as the flow F5 to the inlet openings 11 of the silencer channels 3.
  • the flow distribution chamber 8 has a toroidal cross section and is conically widening.
  • the cross section in a transversal direction regarding the flow F5 is a circular annulus, and the total cross- sectional flow area A5 of the distribution chamber 8 is preferably kept substantially constant over the whole length L3 of the flow distribution chamber 8, as described above.
  • the silencer channels 3 are arranged against the inner surface of the outer casing 23 of the silencer, as can be seen in the figures 2A and 2B.
  • the silencer channels form a peripheral succession of silencer channels 3 on the inner surface of the casing 23, whereby the silencer channels open their inlet openings 11 to the flow distribution chamber 8 and their outlet openings 5 to the mixing chamber 4.
  • the guiding wall 24 with the form of a cone tip in the flow distribution chamber 8 forms a guide for the flow F5 in the flow distribution chamber, and at the same time it closes the area defined by the inner casing 25 of the inner sides of the silencer channels 3 facing each other, such as can be understood from the figures 2A and 2B. Then the flow F5 reaches the mixing chamber 4 only through the silencer channels 3.
  • the total cross-sectional flow area A4 of the mixing chamber 4 is then formed by the total sum of the cross-sectional flow area of the guiding wall 24 and the total combined cross-sectional flow areas of the silencer channels 3, or by the area defined by the silencer's outer casing 23. As described above, this total cross-sectional flow area A4 is substantially larger than the total combined cross-sectional flow area A3 of the silencer channels, which on the other hand is approximately as large as the total cross-sectional flow area A5 of the flow distribution chamber and the first cross-sectional flow area Al of the inlet duct.
  • the mixing chamber 4 extends in the flow direction F4 at the conically tapering opposite wall 7, which changes into the outlet duct 2 at the inlet opening 6, through which inlet opening the gases 10 flow into the outlet duct.
  • the silencer channels 3 can be formed in many different ways, of which two are shown in figures 2A and 2B.
  • the silencer channels can be made between the outer casing 23 and inner casing 25 of the silencer, either with radial partitions 26 or by a corrugated plate 27 pushed in between the outer casing 23 and the inner casing 25, whereby this plate is supported on the corrugation tops 28a and the bottoms 28b against the outer casing and the inner casing 25, respectively. Both ways create silencer channels 3 separated from each other.
  • the figures 4 and 5 show a solution which in a way is similar to that in the figures 1 - 2B, but here the silencer tubes 3 are arranged as a rectangular silencer.
  • the silencer channels are arranged against the inner surfaces of the parallel inner walls 29a, 29b of the outer casing 23 of the silencer.
  • the area defined between these silencer tubes is closed in the direction of the flow distribution chamber 8 for instance by a straight guiding wall 24, or by a guiding wall which is cylindrically convex which is not shown in the figures.
  • the flow distribution chamber 8 is rectangular, and it receives two inlet ducts la and lb, of which the first one la is close to the upper side 30a of the casing and the other one close the lower side 30b of the casing, whereby these sides are perpendicular to the side walls 29a and 29b.
  • the outlet duct 2 with its inlet opening 6 is in this case arranged at the lower side 30b of the casing, so that the outlet flow F2 is transversal regarding the inlet flow FI.
  • the distance LI is at least as large as the transversal dimension Wl of the silencer channels.
  • the distance LI is substantially larger than the measure Wl.
  • the mixing chamber 4 is formed by the space close to the side walls and between the plurality of silencer channels and by the space as an extension to them, whereby the cross-sectional flow area A4 of this space is substantially larger than the total combined cross-sectional flow area A3 of the silencer channels 3, in the manner described above.
  • the silencer channels are located on the inner surface of the silencer's casing, in other words far from the central parts of the silencer.
  • This solution provides in an easy way a large cross-sectional flow area for the mixing chamber, but the arrangement results in that the environment of the silencer can affect the temperature of the gas 10 flowing through the silencer channels 3, which again can be either advantageous or disadvantageous.
  • the figures 6 to 8, and the figure 3, show embodiments of the invention where all silencer channels 3 are arranged close to each other. Such an embodiment is advantageous, for instance when the silencer channels are formed by silencer channels between the catalytic surfaces of a catalyser cell.
  • Figure 6 shows an embodiment where the individual silencer channels 3 are abutting each other, whereby they are separated only by the wall thickness of their partitions.
  • the wall thicknesses it is preferable to arrange the wall thicknesses to be as small as possible, observing of course the durability of the silencer channels in the silencer, it was in this case possible to connect the inlet duct 1 to the silencer channels 3 via a flow distribution chamber 8 which is very small, almost infinitesimal.
  • the radial widening P caused by the flow distribution chamber corresponds only to the face surface caused by the partitions of the silencer channels in a direction perpendicular to the inlet flow FI .
  • the mixing chamber 4 is formed partly at the extension of the flow direction F3 of the silencer channels 3 and partly outside the area defined by these extensions, and particularly on that side which in the transversal direction regarding the length of the silencer channels projects outside the longest channels, as can be seen in the figure 6.
  • the outlet duct 2 is arrange in the opposite wall 7 particularly in that area which is outside the extensions of the silencer channels in the flow direction, in other words the axis of the outlet duct is at a distance H from the longest silencer channels 3.
  • Figure 7 shows an embodiment where the inlet duct 1 and the silencer channels 3 are arranged mutually and regarding each other in the same way as in the embodiment of figure 6.
  • the mixing chamber 4 is arranged partly outside the plurality of silencer channels 3 to surround them, and the outlet duct 2 is arranged at that end of the outer casing 23 of the mixing chamber where the inlet flow FI comes into the silencer.
  • the outlet flow F2 in the silencer is generally opposite to the inlet flow FI in the ducts, which of course are arranged next to each other, as can be seen in figure 7.
  • the whole mixing chamber 4 surrounds the plurality of silencer channels 3, whereby the silencer channels very well will maintain the temperature of the gas 10, if this is required.
  • the mixing flow F4 certainly has to make an essential change of the direction close to the opposite wall 7, but this does not critically increase the flow resistance, as long as the distance LI between the opposite wall 7 and the outlet openings 5 of the silencer channels 3 is sufficiently long, in this case preferably a multiple of the transversal dimension Wl of a single silencer channel.
  • the mixing flow F4 propagates in the opposite direction regarding that of the flow F3 in the silencer channels, and finally it reaches the inlet opening 6 of the outlet duct 2.
  • a silencer of this type can be placed for instance in the engine compartment of a car, and then it is particularly advantageous to arrange the silencer channels 3 so that they are formed by the flow channels between the catalytic surfaces of a catalyser cell 9.
  • Figure 8 shows an embodiment where the inlet duct 1, the flow distribution chamber 8 and the silencer channels 3 are arranged in the same way as in the embodiment of figure 6 regarding the flows FI, F5 and F3.
  • the silencer channels 3 are different from the other embodiments regarding the outlet openings 5 such that the outlet openings are located in the side surface of each silencer channel 3, as can be understood from the figure on the basis of the lines representing the flow 3 and the reference numerals 5 of the outlet openings.
  • the inlet opening 6 of the outlet duct 2 can be arranged directly in register with the mechanical direction of the silencer channels 3, because the flow coming from the outlet openings 5 anyhow meets the above described requirement, in other words that the outlet opening of a silencer channel is not in the direction of the extension of the flow F3 from the silencer channels 3.
  • the outer casing 23 of the mixing chamber 4 is further shaped so that it is widening in a horn-like manner from the region 35 toward the inlet opening 6 of the outlet duct.
  • the outlet duct 2 may open for instance without any obstacles directly into the surrounding external space 22 with a cross-sectional flow area A2', as shown with a continuous line in figure 8, or alternatively it may be redirected to a tapering extension of the outlet duct 2 with a cross-sectional flow area A2", as shown with dotted lines in the figure.
  • the extension of the outer casing 23 can also be omitted, whereby the mixing chamber is completely or approximately straight in the direction of the flow in it.
  • the outlet duct 2 discharges directly into the external space 22 the free edge 33 of the mixing chamber which joins the external space will form the effective inlet opening. Also these structures operate as effective silencers.
  • Figure 3 shows an embodiment where two sets of silencer channels 3 a and 3b are arranged in series in the direction of the gas flows F5, F3a, F4a, F3b, F4b.
  • the first silencer channels 3 a are located in a similar manner as in figure 1, so that they begin inwards from the silencer's outer casing 23.
  • the difference is that in this case there are silencer channels 3 a in the direction of the radius R, if the silencer has a circular cross section, or generally from the outside to the inside in many layers.
  • the space left empty by the silencer channels 3a is also in this case closed by a guiding wall 24 on the side of the flow distribution chamber 8, whereby the flow F5 is distributed approximately evenly into the first silencer chan- nels 3a.
  • the flow F3a is retarded to a flow F4a in the first mixing chamber 4a having the cross-sectional flow area A4a, which again is substantially larger than the cross-sectional flow area A3a of the first silencer channels 3a.
  • the flow F4a contracts again into the second set of silencer channels 3b, as the flow velocity in- creases, whereby the channels contain a flow F3b.
  • the second silencer channels 3b are arranged at the central parts of the silencer, and an annular flange 34 closes the gap between their outer edges and the outer casing 23.
  • silencer channels 3 in series in the direction of the flow, whereby there may be one or two sets as shown in the figures, and moreover also three, four or more sets.
  • this plurality of silencer channel 3 sets one or some may be formed by flow channels between the catalytic surfaces of a catalyser cell, an a part may be formed by chemically passive channels, which are described in connection with the figures 1 - 2B, figures 4 - 6, and figure 8.
  • the figure 9 shows an embodiment where the inlet duct 1, the flow distribution chamber 8, and the silencer channels 3 are of the same type as those which were presented in connection with figure 8.
  • a catalyser cell 31 is placed immediately after the silencer channels, whereby the cell preferably comprises plate-like catalytic surfaces in the direction of the flow, although it would be also possible to use a catalyser of the mass type.
  • the channels between the catalytic surfaces of the catalyser cell 31 are equally long and thus they are not silencer channels, and immediately downstream of this cell there is a mixing chamber 4 according to the invention where the flows F3 with different phases coming from the silencer channels 3 finally are retarded in the large cross-sectional flow area A4 and mixed in the manner described above.
  • this embodiment can also use catalyser cells comprising a porous mass or similar.
  • this structure is at least approximately as efficient as the above described. In other respects the earlier described features are applicable to this embodiment.
  • Figure 10 shows an embodiment where the inlet duct 1, the flow distribution chamber 8, and the silencer channels 3 are of the same type as those presented in connection with figure 6.
  • a particle filter 32 is located immediately af- ter the silencer channels, the filter comprising a suitable porous filter material.
  • the actual mixing chamber 4 according to the invention is downstream from the particle filter 32, which thus does not contain silencer channels, and in the mixing chamber the flows F3 with different phases discharged from the silencer channels 3 are finally retarded in the large cross-sectional flow area A4 and mixed in the manner de- scribed above.
  • the cross- sectional flow area of the particle filter 32 increases in the flow direction F3 -> F4, so that the flow coming from the silencer tubes will be retarded, and the different phases are mixed already in the particle filter, so that the particle filter 32 must be regarded as a part of the mixing chamber 4.
  • the rest of the mixing chamber 4 is continuous and open, but it could also contain a partition or similar for preventing the gas flow directly to the outlet duct 2 due to the inertia forces, as was described above.
  • this structure is also an at least approximately as efficient silencer as they are. In other respects the above described is applicable to this embodiment.
  • Figure 11 shows an embodiment which is quite close to the embodiments of figures 9 and 10.
  • the inlet duct 1, the flow distribution chamber 8, and the silencer channels 3 are of the same type as was shown in connection with figures 6 and 10.
  • a particle filter 32 or catalyser 31 which comprises a suitably porous filtering material.
  • This particle filter 32 and the catalyser cell 31 have an internal structure which is of the same type as in the figures 9 and 10 and as is described later.
  • the particle filter 32 or catalyser cell 31 form the mixing chamber 4, either totally or mainly, as in the figure 11.
  • the mixing chamber 4 is thus formed by the space defined by the particle filter or catalyser cell, and thus this does not necessarily require any other substan- tially open space for the mixing chamber, and the particle filter 32 and/or catalyser cell 31 have the described large cross-sectional flow area A4.
  • the sub-flows of gas F3 with different phases coming from the silencer tubes 3 are retarded and substantially mixed to the mixing flow F4 inside the particle filter or catalyser cell.
  • both the particle filter 32 and the catalyser cell 31 can be of any type. In other respects the earlier described is applicable to this embodiment.
  • FIG 12 shows an embodiment of the invention which in other respects has silencer channels 3 of the basically same type as was described in connection with the figures 1 - 2B, 4 - 6 and 7 - 11, except that the interiors of the silencer channels are filled with catalytic material 33.
  • the structure has silencer channels tightly ad- jacent but separate from each other and having different lengths L2, in each of which the interior generally comprises catalytic material 33, which may be of any type which is suitable for the purpose and enables the flow-through of gases, such as the types described in the paragraph below.
  • the catalytic material 33 comprises plate-like or tube-like parts, i.e. contains channels, it is appropriate in this embodi- ment that these catalyser channels have transversal dimensions which are substantially smaller than the actual silencer channels 3. It also possible to use catalytic material 33 of the mass type.
  • the silencer channels according to the invention can be formed by flow channels between catalytic surfaces of a catalyser, and particularly in order to purify the exhaust gases of combustion engines and at the same time to attenuate sound in the same multi-purpose channel members, as was described in connection with the figures 3 and 7.
  • a catalyser cell of the plate or sheet type which com- prises catalytic material coated on metal plates or ceramic plates or on any other possible plate-like components, between which there are left identifiable openings, holes, channels or corresponding flow passages.
  • the silencer channels in applications of this type can be shaped to have different lengths according to the invention.
  • a large number of such plates are arranged in a pile in the cata- lyser cell, which pile in addition can be turned around one or more lines parallel to the planes of the plates so that a spiral shape is obtained.
  • the above mentioned catalyser cell means particularly a cell which comprises thin plates or tubes, which are coated with catalytic material and between which plates or within which tubes there are left distinct flow channels, even if they often would be very small.
  • Obviously such a cell can be manufacture in many different ways, but as this invention does not primarily relate to catalytic cells they will not be described in greater detail here.
  • a cell of the described type is suitable to be used in connection with the invention.
  • a catalyser cell is located downstream of the silencer tubes, or alternatively before the silencer tubes, before the silencer, as seen in the flow direction of the gases, it is pos- sible to use a catalyser cell of any type, such as a cell comprising plate- like catalytic components described above, or alternatively a porous catalytic mass through which e.g. the exhaust gas passes.
  • a catalyser of the mass type which were mentioned in the general part of this application in connection with the absorption silencers.
  • the above de- scribed particle filter can be of a type which collects small and/or very small particles from for instance exhaust gases, and because a silencer according to the invention placed in a suitable place can be made to operate at a very high temperature, this combination results in that the collected particles will burn in the particle filter.
  • the particles are generally mainly soot or carbon, the combustion products are discharged in a gaseous form. Then the micro particles can be removed from the exhaust gases with the aid of a self-cleaning particle filter, which is also one of the advantages obtained with the invention, when required.
  • silencers according to the invention which are of another type.
  • the silencer channels are straight, but it must be understood that they can also be arcuate, meandering, or have other shapes or shapes varying, either mutually differently or in the same way.
  • the cross-sectional shape of the silencer channels 3 and the mixing cham- ber 4 can vary in a wide range and have a very different shape.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Exhaust Silencers (AREA)

Abstract

Cette invention concerne un silencieux qui peut être utilisé pour les gaz d'échappement ou pour l'air aspiré dans un moteur à combustion interne, ainsi que pour tout autre débit de gaz pulsé. Ce silencieux peut être connecté entre le conduit du débit entrant (1), qui possède une première surface d'écoulement (A1) au niveau de la section transversale, et le conduit du débit sortant (2). Le silencieux comprend plusieurs canaux individuels d'atténuation du bruit (3) qui possèdent des longueurs différentes et qui sont parallèles au débit (F3). Les gaz (10) s'écoulent à travers les canaux d'atténuation du bruit depuis le conduit du débit entrant vers le conduit du débit sortant. La surface d'écoulement totale et combinée (A3) au niveau de la section transversale de tous les canaux n'est pas beaucoup plus petite que la première surface d'écoulement (A1). Ce silencieux comprend en outre une chambre de mélange (4) qui est disposée entre les ouvertures de sortie (5) des canaux d'atténuation du bruit (3) et le conduit du débit sortant (2). Les canaux d'atténuation du bruit donnent dans la chambre de mélange qui est commune à tous les canaux. La surface d'écoulement (A4) au niveau de la section transversale de ladite chambre de mélange est sensiblement plus importante que la surface d'écoulement totale et combinée (A3) au niveau de la section transversale de tous les canaux d'atténuation du bruit.
PCT/FI1999/000417 1998-05-14 1999-05-14 Silencieux pour debits de gaz WO1999058824A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU41471/99A AU4147199A (en) 1998-05-14 1999-05-14 Muffler for gas flows

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI981074A FI981074A (fi) 1998-05-14 1998-05-14 Äänenvaimennin kaasuvirtauksia varten
FI981074 1998-05-14

Publications (1)

Publication Number Publication Date
WO1999058824A1 true WO1999058824A1 (fr) 1999-11-18

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PCT/FI1999/000417 WO1999058824A1 (fr) 1998-05-14 1999-05-14 Silencieux pour debits de gaz

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AU (1) AU4147199A (fr)
FI (1) FI981074A (fr)
WO (1) WO1999058824A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0995896A3 (fr) * 1998-10-19 2000-08-02 Honda Giken Kogyo Kabushiki Kaisha Silencieux d'admission pour véhicule automobile
NL1019418C2 (nl) * 2001-11-23 2003-05-27 Holding H J Bruin B V Aggregaat.
WO2003044366A1 (fr) * 2001-11-23 2003-05-30 Holding H.J. Bruin B.V. Insonorisation destinee a un moteur
JP2013015118A (ja) * 2011-07-06 2013-01-24 Toyota Boshoku Corp 吸音構造体
US11549414B1 (en) * 2019-11-07 2023-01-10 Phillip M. Adams Sound attenuator apparatus and method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB275437A (en) * 1926-09-20 1927-08-11 Joseph Blanchard Improvements in exhaust gas mufflers for internal combustion engines
DE599295C (de) * 1934-07-11 Starke & Hitzeroth Schalldaempfer fuer Brennkraftmaschinen
DE654804C (de) * 1937-12-30 Jakob Stutz Schalldaempfer fuer Brennkraftmaschinen
CH306755A (de) * 1952-11-29 1955-04-30 Ag Techag Schalldämpfer.
CH343711A (fr) * 1958-06-26 1959-12-31 Montavon Roland Silencieux pour échappement de moteur à explosion
GB1374064A (en) * 1972-05-31 1974-11-13 Grace W R & Co Auto exhaust catalyst system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE599295C (de) * 1934-07-11 Starke & Hitzeroth Schalldaempfer fuer Brennkraftmaschinen
DE654804C (de) * 1937-12-30 Jakob Stutz Schalldaempfer fuer Brennkraftmaschinen
GB275437A (en) * 1926-09-20 1927-08-11 Joseph Blanchard Improvements in exhaust gas mufflers for internal combustion engines
CH306755A (de) * 1952-11-29 1955-04-30 Ag Techag Schalldämpfer.
CH343711A (fr) * 1958-06-26 1959-12-31 Montavon Roland Silencieux pour échappement de moteur à explosion
GB1374064A (en) * 1972-05-31 1974-11-13 Grace W R & Co Auto exhaust catalyst system

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0995896A3 (fr) * 1998-10-19 2000-08-02 Honda Giken Kogyo Kabushiki Kaisha Silencieux d'admission pour véhicule automobile
US6804360B1 (en) 1998-10-19 2004-10-12 Honda Giken Kogyo Kabushiki Kaisha Air intake noise reduction apparatus for automotive vehicle
NL1019418C2 (nl) * 2001-11-23 2003-05-27 Holding H J Bruin B V Aggregaat.
WO2003044366A1 (fr) * 2001-11-23 2003-05-30 Holding H.J. Bruin B.V. Insonorisation destinee a un moteur
GB2397636A (en) * 2001-11-23 2004-07-28 Holding H J Bruin B V Sound insulation for engine
GB2397636B (en) * 2001-11-23 2005-08-10 Holding H J Bruin B V Sound insulation for engine
JP2013015118A (ja) * 2011-07-06 2013-01-24 Toyota Boshoku Corp 吸音構造体
US11549414B1 (en) * 2019-11-07 2023-01-10 Phillip M. Adams Sound attenuator apparatus and method
US11988123B1 (en) 2019-11-07 2024-05-21 Phillip M. Adams Sound attenuator apparatus and method

Also Published As

Publication number Publication date
AU4147199A (en) 1999-11-29
FI981074A0 (fi) 1998-05-14
FI981074A (fi) 1998-05-19

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