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
  • F01N13/18—Construction facilitating manufacture, assembly, or disassembly
  • F01N13/1872—Construction facilitating manufacture, assembly, or disassembly the assembly using stamp-formed parts or otherwise deformed sheet-metal
• • 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
• • 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
• • 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
  • F01N13/18—Construction facilitating manufacture, assembly, or disassembly
  • F01N13/1888—Construction facilitating manufacture, assembly, or disassembly the housing of the assembly consisting of two or more parts, e.g. two half-shells
• • 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
  • F01N2260/00—Exhaust treating devices having provisions not otherwise provided for
  • F01N2260/18—Exhaust treating devices having provisions not otherwise provided for for improving rigidity, e.g. by wings, ribs

Definitions

• the invention relates to a silencer and a method for its design according to the preamble of the independent claims.
• Another important economic goal for an exhaust system is a low price.
• a low weight and compact dimensions, which are important for integration into the vehicle, are becoming increasingly important.
• a complete exhaust system from the exhaust manifold to the tailpipe can weigh between 20 and 45 kg. All components influence the acoustics of the exhaust system, but in very different ways.
• Both the objective evaluation of the noise emission from the mouth and the surface of the exhaust system, which is known to be important for the noise emission when accelerating past, and the subjective perception of the observer about the sound image play an important role.
• the acoustics of the exhaust system depend not only on the engine's gas exchange noise but also to a large extent on the design of the exhaust system.
• the multi-valve technology of the drive which is increasingly common today, leads to a significant increase in the noise level entering the exhaust system.
• the future further reduction of the noise limit of the accelerated pass requires a significant reduction in the Mouth noise. This required level reduction has hitherto been achieved essentially by increasing the volume of the silencers, but this quickly reaches the limits of the available installation space.
• shell-type silencers are increasingly being used in medium-sized vehicles as well.
• These shell mufflers usually have a large and flat surface that promotes sound radiation.
• Such a shell muffler is for example in the MTZ Motortechnische Zeitschrift, volume 62, 2001, vol. 3, p. 3 ff.
• the surface of the exhaust system as a sound source has become significantly more important in the design of exhaust systems in recent years.
• the surface sound radiation can even be dominant.
• the noise emission and thus the layout of the exhaust system must be evaluated and optimized. If this is not done, there is a great risk that an unfavorable distribution of the muffler volume and arrangement of the muffler will result in significantly more volume being installed than is necessary, or that concessions will be required regarding the exhaust gas back pressure and thus the performance loss of the vehicle's internal combustion engine.
• the increase in volume also leads to a further, undesirable weight gain.
• the layout of the exhaust system not only significantly influences the noise emission via the volume distribution and length of the connecting pipes, but also through the associated mass distribution and total mass the natural resonance behavior of mechanical vibrations, which affects both the fatigue strength of the system and the noise level in the passenger compartment.
• the trend is more towards reducing the ratio of surface area to volume of the silencer.
• Both the structure-borne noise and the sound radiation depend on the physical parameters of the silencer component. Such parameters are the bending stiffness and the mass assignment of the component, which are determined by the component geometry. Material properties such as the modulus of elasticity and density also have an influence, which are determined by the material used and are therefore not significantly variable.
• the damping of the component is an essential parameter, but difficult to quantify. The change in certain sizes can have different effects on structure-borne noise and radiation. So enlarges the Bending rigidity generally means a reduction in the structure-borne noise, but generally an increase in the radiation dimension, with the structure-borne noise being mostly dominant. Even for simple geometries, modeling and predicting the properties of the later component is difficult because the parameters interact with each other in a very complex manner.
• beads into the surface of the silencer. Beads with various shapes are known, such as earthworm beads or golf ball beads.
• Earthworm beads are elongated structures which are shaped like an earthworm, while golf ball beads are concave or convex hemispherical structures in the manner of golf balls.
• golf ballis beads are e.g. known from the magazine Automobilindustrie 6/2002.
• an exhaust silencer which is made from half-shells which have an essentially flat bottom.
• several outward elongated bulges or beads are provided.
• the beads stiffen the housing and, as mentioned above, contribute to reducing sound excitation as a result of vibrations.
• the beads form corresponding bulges in the interior of the muffler housing, which create additional volumes in the interior of the muffler housing beyond the level of the floor.
• the object of the invention is to provide a silencer with further improved damping properties, and a method for its design.
• an optimized housing surface with beads is provided, the shape and / or the arrangement of the beads being distinguished by targeted irregularity in order to reduce the sound radiation from the muffler.
• beads according to the invention generally have no line of symmetry in the cross-sectional area parallel to the housing surface of the muffler.
• the area proportion of the individual beads preferably has a broad distribution in relation to the total area of the muffler.
• FIG. 1 is an oblique view from above of a silencer with preferred beads, which are represented by isolines,
• FIG. 2 is a top view obliquely from below of the silencer from FIG. 1 with preferred beads
• FIG. 3 shows a view of the interior of a silencer with functional surfaces which divide the silencer into segments
• Fig. 8 shows the comparison of the sound levels for classic beads (a 0 , b 0l c 0 ) and beads according to the invention (a- ,, b- ,, ci).
• the function of known beads in a silencer housing is primarily to increase the bending stiffness of the housing and the flow guidance.
• Surfaces of the muffler housing are also usually subdivided by functional surfaces. These parts of the housing surface generally serve as a seat for floors.
• the sub-areas each act as reflection chambers in the interior of the muffler, in which the sound is to be damped, usually parallelism between the floor seats.
• a minimum number of floors must be provided in which beads are regularly inserted.
• Shape and / or arrangement of the beads can be determined in a preferably numerical optimization process, which results in the lowest possible sound radiation from the muffler.
• a numerical determination of the gas pulsation in the silencer is carried out, ie. H. of a pressure field p (x, t, u (x)).
• x denotes a location on the inner surface of a silencer housing. Since the
• Width and height is small, is preferably the difference between interior and
• t denotes the time and u (x) a displacement vector of the outer surface of an infiltrated silencer to that
• the size u (x) therefore defines the beads.
• Displacement vector u (x) is often negligible.
• a pressure field v (x, t, u (x)) on the outer surface of the silencer results from the pressure field p (x, t, u).
• This velocity field v (x, t, u (x)) leads to the emission of sound.
• the housing surface is now characterized by the fact that the noise emission is reduced or limited to a permissible value.
• FIG. 1 shows a top view of a silencer according to the invention with a base body known per se from two half shells and a number of beads
• FIG. 2 shows a view of the underside of the silencer of FIG. 1.
• the beads can extend both inside the silencer and out of the silencer.
• the half-shells of the preferably predetermined basic body can be single-walled or double-walled.
• the muffler comprises a muffler housing 1 with at least one inlet 3 and an outlet 4 for an exhaust gas, to which one or more customary openings and pipes running inside the muffler can be assigned.
• One or more functional surfaces 8 and one or more beads 5, 6, 7 are embedded in the housing surface 2. For the sake of clarity, not all of the existing beads are marked, but are easily recognizable in the figures due to their irregular shapes.
• the functional surfaces 8 divide the muffler into three inner segments 9, to which the end pieces of the muffler housing 1 are connected on both sides are also provided with beads 5, 7.
• the functional surfaces 8 are bead-like, but their primary task is to ensure that the muffler is seated on the floor.
• FIG. 3 shows the interior view of a muffler 1 without a housing 2, so that only the inside pipes 11 for exhaust gas routing and frames for floors 10 can be seen.
• the floors 10 correlate with the position of the functional surfaces 8 and define segments 9 lying between them.
• the exhaust gas pulsations in the tubes 11 are a source for the emitted sound.
• Classic beads known from the prior art are distinguished by a shape with contours with high symmetry, such as. B. the trapezoidal bead, the cross section of which is trapezoidal, or the earthworm bead.
• the classic earthworm bead With the classic earthworm bead, a steady line of symmetry can easily be found, the distance from the bead edge of which is distinguished by the fact that two opposite edge points can be found to a point on the line of symmetry, the normal distance from this point on the line of symmetry being essentially the same, whereby surfaces are viewed parallel to the housing surface 1.
• the connecting line between the two edge points Ri and R 2 and the point P on the symmetry line Sp, with the tangents T 1 , T 2 of the edge curves of the beads in each of the two edge points, produces two angles ⁇ i and ß ⁇ as well as ⁇ 2 and ß 2 .
• the angles ⁇ , ⁇ fluctuate so that ⁇ 1 is not equal to ⁇ 2 with a deviation of at least ⁇ 1 °, preferably ⁇ 10 °.
• the angles ⁇ i and ⁇ 2 can be unequal with a deviation of ⁇ 5 °, preferably ⁇ 10 °.
• FIG. 4b shows a cross-sectional illustration along a sectional plane A - A 'of the earthworm bead 4a.
• the inner contour IK of the earthworm bead has an approximately circular shape, but is also triangular or the like in the prior art.
• the inner contour of a bead fluctuates.
• a varying radius of curvature can be provided.
• the inner contour of the cross section can fluctuate along a longitudinal line L, the longitudinal line L is a parameter curve which runs along a longitudinal extent of the bead and is generally not symmetrical to the edge curves of the bead and characterizes the length of the bead.
• beads with longitudinal symmetry there are also beads with rotational symmetry in the prior art, such as the golf ball bead mentioned.
• symmetry elements are made to coincide by rotation about an axis of symmetry.
• increased sound attenuation is achieved if such beads are selectively subjected to increased irregularity due to fluctuations in the symmetry angle.
• the line of symmetry of known beads depending on the type of bead, for example in the case of a golf ball bead, can also degenerate to a point of symmetry, since a golf ball bead can have any number of symmetry surfaces.
• bilaterally symmetrical beads are known, which can be broken down into two mirror-identical halves by a plane.
• Corresponding beads according to the invention are characterized at least by fluctuations in the symmetrical elements of such classic beads.
• the normal distance between the two edge points deviates at most by ⁇ 10%, preferably ⁇ 5%, particularly preferably ⁇ 1% from the characteristic bead width.
• Such deviations can e.g. B. result from manufacturing tolerances and are not specifically introduced within the meaning of the invention.
• the known beads are further characterized by the fact that their borders are formed by straight sections and essentially uniformly curved regions, the curvature of the base body not being taken into account in this characterization.
• the radii of the border are therefore such that they are practically only a few discrete ones Accept values.
• the shape and / or arrangement of the beads 5, 6, 7 according to the invention have deliberate irregularities.
• the targeted irregularities of the beads 5, 6, 7 according to the invention can have one or more from the group of the following properties:
• the shape of the bead 5, 6, 7 has a reduced symmetry.
• the beads 5, 6, 7 in the sectional plane parallel to the housing surface 2 are essentially free of symmetry lines with respect to their border curve lying in the sectional plane.
• the beads 5, 6, 7 preferably have no axis of symmetry or line of symmetry. In this case, it should be expedient to standardize on planarity, since the beads are spatial structures and lines of symmetry of the beads are formed from points of local symmetry according to the prior art.
• Circumferential curves of the beads 5, 6, 7 have curvatures with an essentially continuous distribution.
• the curved portion of the curve of the circumferential edge of beads 5, 6, 7 based on a single bead is preferably at least 30%.
• the straight portion of the circumferential curves is preferably a minimum of 10%, whereby “straight” is preferably understood to mean at least 1 cm in length and a deviation of at most 1 mm can be observed over 1 cm.
• the curvature of the base body of the muffler housing 1 is expediently removed here.
• the insertion depth of the beads 5, 6, 7 fluctuates relative to the housing surface; in particular, 80% of the surface lying in the bottom of the bead has a change in height of 30%, 40%, 50% or 60% of the deepest press-in depth.
• the beads 5, 6, 7 are not straight strip beads; in particular, they have no line of symmetry.
• the beads are preferably arranged in the housing surface with a specific disorder to reduce the sound radiation.
• the arrangement can be along a longitudinal or transverse direction of the silencer housing (1). Depending on the position of the beads on the housing surface, the bending stiffness changes in particular even when the component geometry is otherwise unchanged.
• Fig. 1 Sk denotes a bead with an enclave, in which an unsealed island is arranged inside a bead. Areas of the surface that are associated with the original surface of the muffler housing 1 are referred to as unsinked here.
• unsinked Areas of the surface that are associated with the original surface of the muffler housing 1 are referred to as unsinked here.
• circular structures can result, but irregularities occur due to the outer contour of the bead or the inner contour of the bead or the contour of the enclave or island, or both.
• more complicated shapes with more than one unsinked enclave can also be provided.
• the area proportion of individual beads 5, 6, 7 fluctuates in relation to the total area of all beads 5, 6, 7, in particular there are individual beads 5, 6, 7 which differ significantly in their area from the areas of other beads 5, 6, 7 lift off. This is shown in FIG. 5.
• a majority of the beads 5, 6, 7 have a relatively small area.
• 25 of 28 beads have an area below 100 cm 2
• a few individual beads have significantly larger areas up to 250 cm 2 .
• the curvature of the border curves of the beads 5, 6, 7 is subject to a broad distribution and is not characterized by a few discrete values. For example, at least 2, 3 or 4 different values of radii of curvature are provided.
• radii of curvature have different values if they lie outside of predetermined tolerance bands. Examples of this are deviations of 0.5 mm, 1 mm, 2 mm, 3 mm or 5 mm, in particular for beads with an area> 1 cm 2 .
• around 30% of the beads 5, 6, 7 with an area> 1, 5 cm 2 preferably have radii of curvature with the ratio> 1, 5.
• the area proportion of all beads 5, 6, 7 in relation to the entire surface of the silencer 1 is preferably at most 50%, particularly preferably at most 30%.
• the corrugation area proportion on the individual floors 9 defined by functional areas 8 can be between approximately 3% and approximately 70%, preferably between 5% and approximately 60%, of the respective outer surface of the housing 1.
• the area of the individual beads 5, 6, 7 is between 0.05% and 10% of the total surface area, preferably between 0.1% and 5%. This is shown in FIG. 4.
• Beads has a surface area share of at most 2% of the total surface, while a few beads take up much larger areas of up to 5%.
• the absolute number of beads can of course be different for different silencers and individually adjusted.
• FIG. 5 shows a preferred distribution of beads according to the invention based on the area proportion of the beads.
• the abscissa shows the relative number of beads S and the ordinate shows the relative area percentage.
• a straight line results as the distribution.
• a sublinear distribution of the areas over the number of beads is preferred, as can be seen from the curve below the straight line.
• the area is 0.1. This means that 25% of the beads according to the invention take up an area share of less than 0.1 of the total bead area of the beads according to the invention.
• a value of F / S 0.85 results in an area percentage of 0.6. This means that almost 75%) of the beads occupy an area of 0.6.
• steps are provided in the beads according to the invention, which can have irregularities to reduce the sound radiation.
• Beads with a bottom substantially parallel to the housing surface (2) are preferred if the bead reaches or exceeds a certain predetermined depth.
• beads, in particular less deep beads, with an inclined bottom are also provided.
• the curves a 0 , a 1 give the Sound radiation from the left, b 0 , ⁇ the sound radiation from the right area and c Q , ci the sound radiation from the middle area of the muffler housing 1 again.
• the sound radiation was determined at a distance from the muffler housing 1 which is still sufficient to be able to distinguish acoustically different areas of the muffler, a sound radiation having a frequency mixture in the range around 250 Hz being generated.
• the curve family a 0 , b 0 , c 0 was obtained from a silencer, which is provided with the usual, classic beads. All three curves increase monotonically on average with increasing engine speed, e.g.
• a 0 , b 0 in this example between 1000 and 5000 1 / min from about 70 to a maximum of 100 dB, with the middle area generating about 5 dB less sound radiation than the two end areas, whose sound radiation is approximately the same size.
• a similar silencer housing configuration is provided with beads 5, 6, 7 according to the invention, then a clear reduction in the sound radiation is evident.
• the sound radiation is on average around 10 dB lower than the values of the family of curves a 0 , b 0 , c 0 with the known beads.
• a muffler according to the invention can do with a smaller number of floors than a muffler in a classic design. This enables simplified production with the corresponding savings potential in terms of production costs, processing time and tools.
• the number of floors 9 can be compared to an arrangement with regular beads at least one floor 9.
• a significantly lower level of sound radiation can be achieved.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Exhaust Silencers (AREA)

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• 2002
  • 2002-09-17 DE DE10243225A patent/DE10243225A1/de not_active Withdrawn
• 2003
  • 2003-09-17 ES ES03767495T patent/ES2285197T3/es not_active Expired - Lifetime
  • 2003-09-17 EP EP03767495A patent/EP1540148B1/fr not_active Expired - Lifetime
  • 2003-09-17 DE DE50307035T patent/DE50307035D1/de not_active Expired - Lifetime
  • 2003-09-17 WO PCT/EP2003/010344 patent/WO2004027231A2/fr active IP Right Grant
  • 2003-09-17 CN CNB038220709A patent/CN100366868C/zh not_active Expired - Fee Related
  • 2003-09-17 AT AT03767495T patent/ATE359434T1/de not_active IP Right Cessation

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