WO2001014169A1 - Heat shield for motor vehicles - Google Patents

Heat shield for motor vehicles Download PDF

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Publication number
WO2001014169A1
WO2001014169A1 PCT/EP2000/007946 EP0007946W WO0114169A1 WO 2001014169 A1 WO2001014169 A1 WO 2001014169A1 EP 0007946 W EP0007946 W EP 0007946W WO 0114169 A1 WO0114169 A1 WO 0114169A1
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WO
WIPO (PCT)
Prior art keywords
heat shield
heat
perforation
motor vehicles
different
Prior art date
Application number
PCT/EP2000/007946
Other languages
German (de)
French (fr)
Inventor
Helmut W. Diedrichs
Matthias Etzel
Original Assignee
Diedrichs Helmut W
Matthias Etzel
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 Diedrichs Helmut W, Matthias Etzel filed Critical Diedrichs Helmut W
Publication of WO2001014169A1 publication Critical patent/WO2001014169A1/en

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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
    • F01N13/14—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 having thermal insulation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R13/00—Elements for body-finishing, identifying, or decorating; Arrangements or adaptations for advertising purposes
    • B60R13/08—Insulating elements, e.g. for sound insulation
    • B60R13/0876—Insulating elements, e.g. for sound insulation for mounting around heat sources, e.g. exhaust pipes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D25/00—Superstructure or monocoque structure sub-units; Parts or details thereof not otherwise provided for
    • B62D25/20—Floors or bottom sub-units
    • B62D25/2072—Floor protection, e.g. from corrosion or scratching
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B77/00—Component parts, details or accessories, not otherwise provided for
    • F02B77/11—Thermal or acoustic insulation
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general

Definitions

  • the invention relates to a heat shield for motor vehicles for shielding exhaust gas-carrying parts of motor vehicles, consisting of a sheet metal part which is at least partially provided with a perforation.
  • Such heat shields are used to keep the heat radiation from exhaust gas-carrying parts of motor vehicles, in particular the exhaust system, from an adjacent body wall, for example a floor panel of the floor assembly of the motor vehicle. This heat shielding effect is strongest when the heat shield is designed as an unperforated sheet metal part.
  • the heat shields should also absorb the sound emitted by the exhaust gas-carrying parts as effectively as possible.
  • the sound absorbers used here for sound absorption are arranged on the back of the heat shield facing away from the exhaust gas-carrying part. Different embodiments are known for this, for example several metal foil layers with special structures or combinations with knitted mesh or expanded metal or also inorganic absorber materials. In order for these sound absorbers to be effective, it is necessary to establish a sound-permeable connection to the front of the heat shield on which the exhaust gas-carrying part is arranged.
  • the well-known heat shield is therefore provided with a perforation. Adequate sound coupling is only achieved if the perforated area is sufficiently large. Usually more than 25% of the area must be perforated.
  • the holes are made with a diameter of 2.5 - 5 mm.
  • Helmholtz resonators are also known to arrange Helmholtz resonators on the back of the perforated sheet metal part for sound absorption of heat shields.
  • the production and the cost of materials are also relatively high here.
  • the space required for the Helmholtz resonators, in particular when designing for low frequencies, is high; in many cases the required space is not available on the motor vehicle.
  • the object of the invention is therefore to design a heat shield of the type mentioned in such a way that very effective sound absorption is achieved without noticeably impairing the heat shielding effect and without requiring additional space.
  • This object is achieved in that the heat shield is designed as a micro-perforated sheet metal part with hole diameters of less than 1.5 mm, preferably less than 0.7 mm and that there is a cavity between the heat shield and the adjacent body wall.
  • the design of the perforation as microperforation with very small hole sizes means that the heat shielding effect of the heat shield is only very little compared to an unperforated design and is therefore not noticeably impaired in practice.
  • the heat shield forms a highly perforated micro-perforated sound absorber. Sound absorption takes place in that the air mass oscillating between the front of the heat shield and the cavity on the back is so strongly damped by shear forces in the very small holes that broadband sound absorption is achieved.
  • the arrangement of sound absorption elements behind the heat shield is therefore completely eliminated; this space at the back of the heat shield remains as a cavity.
  • microperforated panels as broadband sound absorbers is known per se (DE-GM G 93 20 543.0).
  • this known sound absorber consists of several thin, completely flat plates that are attached to a rigid frame.
  • the multi-layer, complex structure excludes the use in spatially shaped heat shields.
  • the resonance space on the back of the microperforated plate, which is required for a microperforated plate, can be formed in the heat shield according to the invention by the space already present between the heat shield and the adjacent body wall, which - since no separate sound absorption element is required in this area - as an air-filled cavity Available. This eliminates the need for a separate rear wall for sound absorbers with microperforated panels.
  • the heat shield thus constituted is a one-piece molded sheet metal part that retains the high heat shielding effect of an unperforated molded sheet part almost without restriction, but at the same time forms a broadband, very effective sound absorber without the need for an additional sound absorption element.
  • the space required for the cavity to be provided on the back of the sheet metal part is relatively small.
  • the heat shield can be arranged relatively close to the body wall to be shielded. The calculation methods developed for sound absorbers with micro-perforated plates make it possible to predict the sound absorption effect relatively accurately with little effort.
  • the cavity existing between the heat shield and the adjacent wall has different widths. Due to this fact, which can be produced in a simple manner due to the usual shape of body wall sections in motor vehicle construction and / or by suitable shape of the heat shield, the sound absorption effect can also be very simple, particularly with regard to its bandwidth and very particularly with regard to the absorption effect for low frequencies Agents are influenced and adapted to the respective application.
  • the heat shield can be designed without perforation in its area arranged directly above the exhaust gas-carrying part, if a completely unrestricted heat shielding effect is desired in this area.
  • Exemplary embodiments of the invention are illustrated below, which are shown in the drawing. It shows:
  • FIG. 2-9 in a simplified representation different embodiments of the perforation of the heat shield and
  • Fig. 10 in a section corresponding to Fig. 1, a modified version.
  • an exhaust gas-carrying part for example an exhaust line 1 of a motor vehicle, is shielded from an adjacent body wall 2, in the example shown a portion of the bottom wall of a motor vehicle, by a heat shield 3, which is attached to the body wall 2 at its edges ,
  • the heat shield 3 consists, for example, of aluminum and is a sheet metal part which is provided with a perforation 4 at least in some areas.
  • the perforation 4 is designed as a micro perforation.
  • Their holes 5 have hole diameters of, for example, 0.7 mm.
  • the cavity 6 Between the heat shield 3 and the adjacent body wall 2 there is a cavity 6 whose width B, which is determined by the distance between the heat shield 3 and the body wall 2, is different. In a departure from the exemplary embodiment shown, the cavity 6 can also be open on the side and / or front and rear.
  • the different width B of the cavity 6 in different areas of the heat shield 3 leads to a particularly large bandwidth of the absorption effect.
  • FIG. 7 shows an embodiment in which an unperforated area of the heat shield 3 is provided over the exhaust line 1, while its remaining areas show, for example, a uniform hole arrangement.
  • the perforation can also be omitted in the area of breakpoints and folds.
  • the heat shield 3 has only been shown schematically. It is understood that this is usually a spatially deformed sheet metal part.
  • the selected hole sizes can be chosen to be constant or different in the entire heat shield 3 in all the exemplary embodiments shown. This enables the sound attenuation to be influenced in a targeted manner for different frequencies.
  • FIG. 10 shows, in a sectional illustration corresponding to FIG. 1, in addition to the heat shield 5 described, a further heat shield 5 ′ which is arranged below the exhaust line 1 and which prevents heat emission from the exhaust line 1 downward. This precludes material that is located under the vehicle floor, for example leaves or dry grass, from being ignited by the heat radiated from the exhaust line 1.
  • a wall 2 ' is arranged at a distance from the heat shield 3' on the rear of the heat shield 3 ', ie on the underside of the vehicle.
  • a cavity 3 ' is formed in between.
  • the heat shield 3 ' is provided in the manner already described with a perforation 4' designed as a microperforation, the holes 5 'of which, for example, also have a diameter of 0.7 mm.
  • the heat shield 3 ' is attached to the underside of the exhaust line 1, for example by riveting or screwing.
  • the heat shield 3 ' is made together with the wall 2' from a one-piece sheet metal part.
  • the additional heat shield 3 extends laterally to close to the heat shield 3, so that the space surrounding the exhaust line 1 is largely closed.
  • This space can be ventilated and cooled in that the space is open at its front and rear ends, so that an air flow occurs during the journey.
  • the wall 2 'lies approximately in the plane of the floor surface of the motor vehicle, so that the underside of the vehicle is largely smooth, even in the area of the exhaust line 1.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Transportation (AREA)
  • Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Exhaust Silencers (AREA)

Abstract

The invention relates to a heat shield (3) for motor vehicles which is used to shield parts (1) carrying exhaust gas and as an acoustic muffler. The heat shield (3) is configured as a micro-perforated metal plate with perforation diameters of less than 1.5 mm. A cavity (6) is formed between the heat shield (3) and the neighbouring wall (2) which varies in width according to different sections of the heat shield (3).

Description

Hitzeschild für KraftfahrzeugeHeat shield for motor vehicles
Die Erfindung betrifft einen Hitzeschild für Kraftfahrzeuge zur Abschirmung von abgasführenden Teilen von Kraftfahrzeugen, bestehend aus einem Blechformteil, das mindestens teilweise mit einer Lochung versehen ist.The invention relates to a heat shield for motor vehicles for shielding exhaust gas-carrying parts of motor vehicles, consisting of a sheet metal part which is at least partially provided with a perforation.
Derartige Hitzeschilde dienen dazu, die ärmeabstrahlung von abgasführenden Teilen von Kraftfahrzeugen, insbesondere des Abgasstrangs, von einer benachbarten Karosseriewand, beispielsweise einem Bodenblech der Bodengruppe des Kraftfahrzeugs fernzuhalten. Diese Wärmeabschirmwirkung ist am stärksten, wenn der Hitzeschild als ungelochtes Blechformteil ausgeführt wird.Such heat shields are used to keep the heat radiation from exhaust gas-carrying parts of motor vehicles, in particular the exhaust system, from an adjacent body wall, for example a floor panel of the floor assembly of the motor vehicle. This heat shielding effect is strongest when the heat shield is designed as an unperforated sheet metal part.
In den meisten Einsatzfällen wird aber die zusätzliche Forderung erhoben, daß die Hitzeschilde auch den von den abgasführenden Teilen ausgehenden Schall möglichst wirksam absorbieren soll. Die hierbei zur Schallabsorbtion eingesetzten Schallabsorber sind auf der dem abgasführenden Teil abgekehrten Rückseite des Hitzeschildes angeordnet. Hierfür sind unterschiedliche Ausführungsformen bekannt, beispielsweise mehrere Metallfolienlagen mit speziellen Strukturen oder Kombinationen mit Gestrick-Geflecht oder Streckmetall oder auch anorganische Absorbermassen. Um diese Schallabsorber wirksam werden zu lassen, ist es erforderlich, eine schalldurchlässige Verbindung zur Vorderseite des Hitzeschildes herzustellen, auf der das abgasführende Teil angeordnet ist. Deshalb wird der bekannte Hitzeschild mit einer Lochung versehen. Eine ausreichende Schallkoppelung wird aber nur erreicht, wenn die Lochfläche ausreichend groß ist. Üblicherweise müssen mehr als 25 % der Fläche gelocht sein. Die Löcher werden mit einem Durchmesser von 2,5 - 5 mm ausgeführt.In most applications, however, there is an additional requirement that the heat shields should also absorb the sound emitted by the exhaust gas-carrying parts as effectively as possible. The sound absorbers used here for sound absorption are arranged on the back of the heat shield facing away from the exhaust gas-carrying part. Different embodiments are known for this, for example several metal foil layers with special structures or combinations with knitted mesh or expanded metal or also inorganic absorber materials. In order for these sound absorbers to be effective, it is necessary to establish a sound-permeable connection to the front of the heat shield on which the exhaust gas-carrying part is arranged. The well-known heat shield is therefore provided with a perforation. Adequate sound coupling is only achieved if the perforated area is sufficiently large. Usually more than 25% of the area must be perforated. The holes are made with a diameter of 2.5 - 5 mm.
Um eine ausreichende Wärmeabschirmwirkung aufrechtzuerhalten und das Eindringen der Wärme durch die Löcher zu verhindern, ist es bekannt, die Löcher mit einer schalldurchlässigen Aluminiumfolie abzudecken. Nachteilig ist hierbei aber, daß die Wärmeabschirmwirkung im Bereich der mit Aluminiumfolie abgedeckten Löcher erheblich verringert ist.In order to maintain a sufficient heat shielding effect and to prevent the penetration of heat through the holes, it is known to cover the holes with a sound-permeable aluminum foil. The disadvantage here, however, is that the heat shielding effect is considerably reduced in the area of the holes covered with aluminum foil.
Ein weiterer, wesentlicher Nachteil dieser bekannten Hitzeschilde, die gleichzeitig eine schallabsorbierende Wirkung aufweisen, besteht darin, daß sie verhältnismäßig schwer sind und der Herstellungsaufwand wegen des mehrschichtigen Aufbaus hoch ist. Deshalb sind auch die Herstellungskosten verhältnismäßig hoch.Another major disadvantage of these known heat shields, which at the same time have a sound-absorbing effect, is that they are relatively heavy and the manufacturing effort is high because of the multilayer structure. Therefore, the manufacturing costs are also relatively high.
Es ist auch bekannt, zur Schallabsorbtion von Hitzeschilden auf der Rückseite des gelochten Blechformteils Helmholtzresonatoren anzuordnen. Die Herstellung und der Materialaufwand sind auch hierbei verhältnismäßig hoch. Der für die Helmholtzresonatoren erforderliche Platzaufwand, insbesondere bei der Auslegung für niedrige Frequenzen, ist hoch; der erforderliche Platz steht in vielen Fällen am Kraftfahrzeug nicht zur Verfügung.It is also known to arrange Helmholtz resonators on the back of the perforated sheet metal part for sound absorption of heat shields. The production and the cost of materials are also relatively high here. The space required for the Helmholtz resonators, in particular when designing for low frequencies, is high; in many cases the required space is not available on the motor vehicle.
Aufgabe der Erfindung ist es daher, einen Hitzeschild der eingangs genannten Gattung so auszubilden, daß ohne spürbare Beeinträchtigung der Wärmeabschirmwirkung und ohne zusätzlichen Platzbedarf eine sehr wirksame Schallabsorbtion erreicht wird. Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß der Hitzeschild als mikroperforiertes Blechformteil mit Lochdurchmessern von weniger als 1,5 mm, vorzugsweise weniger als 0,7 mm ausgeführt ist und daß zwischen dem Hitzeschild und der benachbarten Karosseriewand ein Hohlraum besteht.The object of the invention is therefore to design a heat shield of the type mentioned in such a way that very effective sound absorption is achieved without noticeably impairing the heat shielding effect and without requiring additional space. This object is achieved in that the heat shield is designed as a micro-perforated sheet metal part with hole diameters of less than 1.5 mm, preferably less than 0.7 mm and that there is a cavity between the heat shield and the adjacent body wall.
Die Ausführung der Lochung als Mikroperforation mit sehr geringen Lochgrößen führt dazu, daß die WärmeabSchirmwirkung des Hitzeschildes gegenüber einer ungelochten Ausführung nur sehr wenig und daher für die Praxis nicht spürbar beeinträchtigt wird. Zugleich bildet der Hitzeschild aber einen mikroperforierten Schallabsorber hoher Wirksamkeit. Die Schallabsorbtion erfolgt dadurch, daß die zwischen der Vorderseite des Hitzeschildes und dem Hohlraum an der Rückseite schwingende Luftmasse in den sehr kleinen Löchern durch Scherkräfte so stark bedämpft wird, daß eine breitban- dige Schallabsorbtion erreicht wird. Die Anordnung von Schallabsorbtionselementen hinter dem Hitzeschild entfällt damit völlig; dieser Raum an der Rückseite des Hitzeschildes verbleibt als Hohlraum.The design of the perforation as microperforation with very small hole sizes means that the heat shielding effect of the heat shield is only very little compared to an unperforated design and is therefore not noticeably impaired in practice. At the same time, the heat shield forms a highly perforated micro-perforated sound absorber. Sound absorption takes place in that the air mass oscillating between the front of the heat shield and the cavity on the back is so strongly damped by shear forces in the very small holes that broadband sound absorption is achieved. The arrangement of sound absorption elements behind the heat shield is therefore completely eliminated; this space at the back of the heat shield remains as a cavity.
Eine für die Herstellung aufwendige Abdeckung der Lochung mit Metallfolie entfällt ebenfalls, da durch die geringe Lochfläche nur sehr wenig Wärme durch den Hitzeschild hindurchdringt .There is also no need for covering the perforation with metal foil, which is expensive to produce, since the small perforated area means that very little heat penetrates through the heat shield.
Die Verwendung mikroperforierter Platten als breitbandige Schallabsorber ist an sich bekannt (DE-GM G 93 20 543.0). Dieser bekannte Schallabsorber besteht aber aus mehreren dünnen, völlig ebenen Platten, die auf einem starren Rahmen befestigt sind. Der mehrschichtige, komplexe Aufbau schließt die Anwendung bei räumlich geformten Hitzeschilden aus. Der für als mikroperforierte Platte ausgeführte Schallabsorber erforderliche Resonanzraum auf der Rückseite der mikroperforierten Platte kann beim erfindungsgemäßen Hitzeschild durch den ohnehin zwischen dem Hitzeschild und der benachbarten Karosseriewand vorhandenen Raum gebildet werden, der - da kein gesondertes Schallabsorbtionselement in diesem Bereich erforderlich ist - als luftgefüllter Hohlraum zur Verfügung steht. Damit entfällt die bei Schallabsorbern mit mikroperforierten Platten notwendige gesonderte Rückwand.The use of microperforated panels as broadband sound absorbers is known per se (DE-GM G 93 20 543.0). However, this known sound absorber consists of several thin, completely flat plates that are attached to a rigid frame. The multi-layer, complex structure excludes the use in spatially shaped heat shields. The resonance space on the back of the microperforated plate, which is required for a microperforated plate, can be formed in the heat shield according to the invention by the space already present between the heat shield and the adjacent body wall, which - since no separate sound absorption element is required in this area - as an air-filled cavity Available. This eliminates the need for a separate rear wall for sound absorbers with microperforated panels.
Insgesamt stellt der so beschaffene Hitzeschild ein einstückiges Blechformteil dar, das die hohe Wärmeabschirmwirkung eines ungelochten Blechformteils nahezu uneingeschränkt beibehält, dabei aber zugleich einen breitbandigen, sehr wirksamen Schallabsorber bildet, ohne daß hierfür ein zusätzliches Schallabsorbtionselement vorgesehen werden müßte .Overall, the heat shield thus constituted is a one-piece molded sheet metal part that retains the high heat shielding effect of an unperforated molded sheet part almost without restriction, but at the same time forms a broadband, very effective sound absorber without the need for an additional sound absorption element.
Gegenüber Hitzeschilden mit auf der Rückseite angeordneten Schallabsorbtionselementen ergeben sich die Vorteile des wesentlich geringeren Gewichts und der Verringerung des Fertigungsaufwands, weil die Anbringung zusätzlicher Schichten, Folien oder sonstiger Schallabsorbtionselemente oder Resonatoren entfällt.Compared to heat shields with sound absorption elements arranged on the rear side, there are the advantages of significantly lower weight and the reduction in production costs, since the application of additional layers, foils or other sound absorption elements or resonators is eliminated.
Auch bei der Auslegung des breitbandigen Schallabsorbers für die beim Kraftfahrzeug im besonderen Maße auftretenden niedrigen Frequenzen ist der Platzbedarf für den auf der Rückseite des Blechformteils vorzusehenden Hohlraum verhältnismäßig gering. Dadurch kann der Hitzeschild verhältnismäßig nahe an der abzuschirmenden Karosseriewand angeordnet werden. Die für Schallabsorber mit mikroperforierten Platten entwickelten Berechnungsmethoden ermöglichen es, mit geringem Aufwand verhältnismäßig genau die Schallabsorbtionswirkung vorherzubestimmen.Even when designing the broadband sound absorber for the low frequencies that occur particularly in motor vehicles, the space required for the cavity to be provided on the back of the sheet metal part is relatively small. As a result, the heat shield can be arranged relatively close to the body wall to be shielded. The calculation methods developed for sound absorbers with micro-perforated plates make it possible to predict the sound absorption effect relatively accurately with little effort.
Gemäß einer bevorzugten Ausführungsform der Erfindung ist vorgesehen, daß der zwischen dem Hitzeschild und der benachbarten Wand bestehende Hohlraum unterschiedlich breit ist. Durch diese Gegebenheit, die auf Grund der üblichen Formgestaltung von Karosseriewandabschnitten im Kraftfahrzeugbau und/oder durch geeignete Formgestaltung des Hitzeschildes in einfacher Weise hergestellt werden kann, kann die Schallabsorbtionswirkung insbesondere auch hinsichtlich ihrer Bandbreite und ganz besonders hinsichtlich der Absorptionswirkung für niedrige Frequenzen, mit sehr einfachen Mitteln beeinflußt und an den jeweiligen Anwendungsfall angepaßt werden.According to a preferred embodiment of the invention it is provided that the cavity existing between the heat shield and the adjacent wall has different widths. Due to this fact, which can be produced in a simple manner due to the usual shape of body wall sections in motor vehicle construction and / or by suitable shape of the heat shield, the sound absorption effect can also be very simple, particularly with regard to its bandwidth and very particularly with regard to the absorption effect for low frequencies Agents are influenced and adapted to the respective application.
Weitere, fertigungstechnisch besonders einfach zu beherrschende Maßnahmen zur gezielten Beeinflussung der Schallabsorbtionswirkung bestehen darin, daß die Lochdurchmesser, die Lochabstände und/oder die Lochanordnungsmuster der Lochung in unterschiedlichen Bereichen des Hitzeschilds unterschiedlich sind. Dadurch läßt sich einerseits die Wärmeabschirmwirkung, andererseits aber auch die Schallabsorbtionswirkung in einzelnen Bereichen in der jeweils gewünschten Weise beeinflussen.Further, technically particularly easy to control measures for specifically influencing the sound absorption effect consist in the fact that the hole diameter, the hole spacing and / or the hole arrangement pattern of the perforation are different in different areas of the heat shield. This allows the heat shielding effect to be influenced on the one hand, but also the sound absorption effect in individual areas in the desired manner.
Beispielsweise kann der Hitzeschild in seinem unmittelbar über dem abgasführenden Teil angeordneten Bereich ohne Lochung ausgeführt sein, wenn in diesem Bereich eine völlig uneingeschränkte Wärmeabschirmwirkung erwünscht ist. Nachfolgend werden Ausführungsbeispiele der Erfindung näher erläutert, die in der Zeichnung dargestellt sind. Es zeigt:For example, the heat shield can be designed without perforation in its area arranged directly above the exhaust gas-carrying part, if a completely unrestricted heat shielding effect is desired in this area. Exemplary embodiments of the invention are illustrated below, which are shown in the drawing. It shows:
Fig. 1 in einem senkrechten Schnitt einen Hitzeschild zwischen einem abgasführenden Teil und einer Karosseriewand eines Kraftfahrzeugs,1 is a vertical section of a heat shield between an exhaust gas-carrying part and a body wall of a motor vehicle,
Fig. 2-9 in vereinfachter Darstellungsweise unterschiedliche Ausführungsformen der Lochung des Hitzeschilds undFig. 2-9 in a simplified representation different embodiments of the perforation of the heat shield and
Fig. 10 in einem Schnitt entsprechend der Fig. 1 eine demgegenüber abgeänderte Ausführung.Fig. 10 in a section corresponding to Fig. 1, a modified version.
Wie in Fig. 1 dargestellt, ist ein abgasführendes Teil, beispielsweise ein Abgasstrang 1 eines Kraftfahrzeugs gegenüber einer benachbarten Karosseriewand 2, beim dargestellten Beispiel einem Abschnitt der Bodenwand eines Kraftfahrzeugs, durch einen Hitzeschild 3 abgeschirmt, der an seinen Rändern an der Karosseriewand 2 befestigt ist.As shown in FIG. 1, an exhaust gas-carrying part, for example an exhaust line 1 of a motor vehicle, is shielded from an adjacent body wall 2, in the example shown a portion of the bottom wall of a motor vehicle, by a heat shield 3, which is attached to the body wall 2 at its edges ,
Der Hitzeschild 3 besteht beispielsweise aus Aluminium und ist ein Blechformteil, das mindestens in Teilbereichen mit einer Lochung 4 versehen ist. Die Lochung 4 ist als Mikroperforation ausgeführt. Ihre Löcher 5 weisen Lochdurchmesser von beispielsweise 0,7 mm auf.The heat shield 3 consists, for example, of aluminum and is a sheet metal part which is provided with a perforation 4 at least in some areas. The perforation 4 is designed as a micro perforation. Their holes 5 have hole diameters of, for example, 0.7 mm.
Zwischen dem Hitzeschild 3 und der benachbarten Karosseriewand 2 besteht ein Hohlraum 6, dessen Breite B, die durch den Abstand zwischen dem Hitzeschild 3 und der Karosseriewand 2 bestimmt wird, unterschiedlich ist. Abweichend von dem dargestellten Ausführungsbeispiel kann der Hohlraum 6 auch seitlich und/oder vorn und hinten offen sein. Der als Blechformteil ausgebildete Hitzeschild 5 bewirkt eine weitestgehende Wärmeabschirmung zwischen dem Abgasstrang 1 und der Karosseriewand 2. Wegen der Lochung 4 bildet der Hitzeschild 3 einen mikroperforierten Schallabsorber. Die Schwingungen der Luftmasse werden in den sehr kleinen Löchern 5 so stark bedämpft, daß eine sehr breitbandige Schallabsorbtionswirkung erzielt wird.Between the heat shield 3 and the adjacent body wall 2 there is a cavity 6 whose width B, which is determined by the distance between the heat shield 3 and the body wall 2, is different. In a departure from the exemplary embodiment shown, the cavity 6 can also be open on the side and / or front and rear. The heat shield 5, which is designed as a molded sheet metal part, provides the greatest possible heat shielding between the exhaust line 1 and the body wall 2. Because of the perforation 4, the heat shield 3 forms a microperforated sound absorber. The vibrations of the air mass are so strongly damped in the very small holes 5 that a very broadband sound absorption effect is achieved.
Die in unterschiedlichen Bereichen des Hitzeschildes 3 unterschiedliche Breite B des Hohlraums 6 führt zu einer besonders großen Bandbreite der Absorbtionswirkung.The different width B of the cavity 6 in different areas of the heat shield 3 leads to a particularly large bandwidth of the absorption effect.
In den Fig. 2-5 sind bei gleichmäßiger Verteilung der Löcher 5 unterschiedliche Lochanordnungsmuster und unterschiedliche Lochabstände der Lochung 4 dargestellt.2-5 different hole arrangement patterns and different hole spacings of the perforation 4 are shown with a uniform distribution of the holes 5.
In den Fig. 6-9 ist gezeigt, daß in unterschiedlichen Bereichen des Hitzeschilds 3 unterschiedliche Ausführungen der Lochung 4 möglich sind, um in diesen unterschiedlichen Bereichen einerseits die Wärmeabschirmwirkung, andererseits aber insbesondere die Schallabsorbtionswirkung unterschiedlich zu gestalten.6-9 show that different designs of the perforation 4 are possible in different areas of the heat shield 3, in order to make the heat shielding effect in these different areas on the one hand, but in particular the sound absorption effect in particular on the other.
So ist in Fig. 6 eine kontinuierliche Veränderung der Lochabstände zu erkennen. Fig. 7 zeigt ein Ausführungsbeispiel, bei dem über den Abgasstrang 1 ein ungelochter Bereich des Hitzeschilds 3 vorgesehen ist, während seine übrigen Bereiche eine beispielsweise gleichmäßige Lochanordnung zeigen. Auch im Bereich von Haltepunkten und Falzungen kann die Lochung weggelassen werden.A continuous change in the spacing between holes can be seen in FIG. 6. FIG. 7 shows an embodiment in which an unperforated area of the heat shield 3 is provided over the exhaust line 1, while its remaining areas show, for example, a uniform hole arrangement. The perforation can also be omitted in the area of breakpoints and folds.
Beim Beispiel nach Fig. 8 sind am Hitzeschild 3 zwei unterschiedliche Lochanordnungsmuster mit unterschiedlichen Lochabständen gewählt. Beim Beispiel nach Fig. 9 ist gezeigt, daß in der Nähe des Abgasstrangs 1 auf jegliche Lochung vollständig verzichtet wurde, um die Wärmeabschirmung in diesem Bereich unbeeinträchtigt zu lassen, während beiderseits des Abgasstrangs 1 unterschiedliche Lochanordnungsmuster mit unterschiedlichen Lochabständen vorgesehen wurden, um unterschiedliche Frequenzen zu dämpfen.In the example according to FIG. 8, there are two different hole arrangement patterns with different ones on the heat shield 3 Hole spacing selected. In the example according to FIG. 9, it is shown that in the vicinity of the exhaust line 1, any perforation has been completely dispensed with, in order to leave the heat shield in this area unaffected, while on both sides of the exhaust line 1 different hole arrangement patterns with different hole spacings have been provided in order to allow different frequencies dampen.
Bei den in den Fig. 2-9 gezeigten Ausführungsbeispielen wurde der Hitzeschild 3 nur schematisch dargestellt. Es versteht sich, daß es sich hierbei üblicherweise um ein räumlich verformtes Blechformteil handelt.In the exemplary embodiments shown in FIGS. 2-9, the heat shield 3 has only been shown schematically. It is understood that this is usually a spatially deformed sheet metal part.
Die gewählten Lochgrößen können bei allen dargestellten Ausführungsbeispielen im gesamten Hitzeschild 3 gleichbleibend oder unterschiedlich gewählt werden. Dadurch ist eine gezielte Beeinflussung der Schalldämpfung für unterschiedliche Frequenzen möglich.The selected hole sizes can be chosen to be constant or different in the entire heat shield 3 in all the exemplary embodiments shown. This enables the sound attenuation to be influenced in a targeted manner for different frequencies.
Fig. 10 zeigt in einer Schnittdarstellung entsprechend der Fig. 1 zusätzlich zu dem beschriebenen Hitzeschild 5 einen unterhalb des Abgasstrangs 1 angeordneten weiteren Hitzeschild 5', der eine Wärmeabstrahlung des Abgasstrangs 1 nach unten verhindert. Damit wird ausgeschlossen, daß Material, das sich unter dem Fahrzeugboden befindet, beispielsweise Laub oder trockenes Gras, durch die vom Abgasstrang 1 abgestrahlte Wärme entzündet wird.FIG. 10 shows, in a sectional illustration corresponding to FIG. 1, in addition to the heat shield 5 described, a further heat shield 5 ′ which is arranged below the exhaust line 1 and which prevents heat emission from the exhaust line 1 downward. This precludes material that is located under the vehicle floor, for example leaves or dry grass, from being ignited by the heat radiated from the exhaust line 1.
Zugleich erfolgt auch im Bereich dieses zusätzlichen Hitzeschildes 3' eine Schallabsorption. Zu diesem Zweck ist an der Rückseite des Hitzeschildes 3', d.h. an der Fahrzeugunterseite, eine Wand 2' im Abstand zum Hitzeschild 3' angeordnet. Dazwischen ist ein Hohlraum 3' gebildet. Der Hitzeschild 3' ist in der schon beschriebenen Weise mit einer als Mikroperforation ausgebildeten Lochung 4' versehen, deren Löcher 5' beispielsweise einen Durchmesser von ebenfalls 0,7 mm haben.At the same time, sound absorption also takes place in the area of this additional heat shield 3 '. For this purpose, a wall 2 'is arranged at a distance from the heat shield 3' on the rear of the heat shield 3 ', ie on the underside of the vehicle. A cavity 3 'is formed in between. The The heat shield 3 'is provided in the manner already described with a perforation 4' designed as a microperforation, the holes 5 'of which, for example, also have a diameter of 0.7 mm.
Der Hitzeschild 3' ist an der Unterseite des Abgasstrangs 1 befestigt, beispielsweise durch Nietung oder Verschraubung. Bei dem dargestellten Ausführungsbeispiel ist der Hitzeschild 3' gemeinsam mit der Wand 2' aus einem einstückigen Blechformteil hergestellt.The heat shield 3 'is attached to the underside of the exhaust line 1, for example by riveting or screwing. In the illustrated embodiment, the heat shield 3 'is made together with the wall 2' from a one-piece sheet metal part.
Der zusätzliche Hitzeschild 3' erstreckt sich seitlich bis nahe an den Hitzeschild 3, so daß der den Abgasstrang 1. umgebende Raum weitgehend abgeschlossen ist. Eine Belüftung und Kühlung dieses Raums kann dadurch erfolgen, daß der Raum an seinem vorderen und hinteren Ende offen ist, so daß während der Fahrt eine Luftströmung entsteht. Die Wand 2' liegt angenähert in der Ebene der Bodenfläche des Kraftfahrzeugs, so daß sich eine auch im Bereich des Abgasstrangs 1 weitgehend glatte Fahrzeugunterseite ergibt. The additional heat shield 3 'extends laterally to close to the heat shield 3, so that the space surrounding the exhaust line 1 is largely closed. This space can be ventilated and cooled in that the space is open at its front and rear ends, so that an air flow occurs during the journey. The wall 2 'lies approximately in the plane of the floor surface of the motor vehicle, so that the underside of the vehicle is largely smooth, even in the area of the exhaust line 1.

Claims

P a t e n t a n s p r ü c h e Patent claims
1. Hitzeschild für Kraftfahrzeuge zur Abschirmung von abgasführenden Teilen von Kraftfahrzeugen, bestehend aus einem Blechformteil, das mindestens teilweise mit einer Lochung versehen ist, dadurch gekennzeichnet, daß der Hitzeschild (3, 3') als mikroperforiertes Blechformteil mit Lochdurchmessern von weniger als 1,5 mm ausgeführt ist und daß zwischen dem Hitzeschild (3, 3') und einer benachbarten Wand (2, 2') ein Hohlraum (6, 6') besteht.1. Heat shield for motor vehicles for shielding exhaust gas-carrying parts of motor vehicles, consisting of a sheet metal part which is at least partially provided with a perforation, characterized in that the heat shield (3, 3 ') as a micro-perforated sheet metal part with hole diameters of less than 1.5 mm is executed and that between the heat shield (3, 3 ') and an adjacent wall (2, 2') there is a cavity (6, 6 ').
2. Hitzeschild nach Anspruch 1, dadurch gekennzeichnet, daß der Lochdurchmesser weniger als 0,8 mm beträgt.2. Heat shield according to claim 1, characterized in that the hole diameter is less than 0.8 mm.
3. Hitzeschild nach Anspruch 1, dadurch gekennzeichnet, daß die dem Hitzeschild (3) benachbarte Wand eine Karosseriewand (2) des Kraftfahrzeugs ist.3. Heat shield according to claim 1, characterized in that the heat shield (3) adjacent wall is a body wall (2) of the motor vehicle.
4. Hitzeschild nach Anspruch 1, dadurch gekennzeichnet, daß der zwischen dem Hitzeschild (3, 3') und der benachbarten Wand (2, 2') bestehende Hohlraum (6,6') unterschiedlich breit ist.4. Heat shield according to claim 1, characterized in that between the heat shield (3, 3 ') and the adjacent wall (2, 2') existing cavity (6,6 ') is of different widths.
5. Hitzeschild nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Lochdurchmesser, die Lochabstände und/oder die Lochanordnungsmuster der Lochung (4) in unterschiedlichen Bereichen des Hitzeschilds (3) unterschiedlich sind. 5. Heat shield according to claim 1 or 2, characterized in that the hole diameter, the hole spacing and / or the hole arrangement pattern of the perforation (4) are different in different areas of the heat shield (3).
6. Hitzeschild nach Anspruch 1, dadurch gekennzeichnet, daß der Hitzeschild (3) in seinem unmittelbar über dem abgasführenden Teil (1) angeordneten Bereich ohne Lochung ausgeführt ist.6. Heat shield according to claim 1, characterized in that the heat shield (3) in its immediately above the exhaust gas-carrying part (1) arranged area is designed without perforation.
7. Hitzeschild nach Anspruch 11, dadurch gekennzeichnet, daß der Hitzeschild (3') unterhalb des Abgasstrangs (1) eines Kraftfahrzeugs angeordnet ist und im Abstand zu dem Hitzeschild (5') eine Wand (2') angeordnet ist. 7. Heat shield according to claim 11, characterized in that the heat shield (3 ') is arranged below the exhaust line (1) of a motor vehicle and a wall (2') is arranged at a distance from the heat shield (5 ').
PCT/EP2000/007946 1999-08-20 2000-08-16 Heat shield for motor vehicles WO2001014169A1 (en)

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DE1999139482 DE19939482B4 (en) 1999-08-20 1999-08-20 Arrangement for shielding exhaust-carrying parts of motor vehicles
DE19939482.2 1999-08-20

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