(19)
(11)EP 3 038 823 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
03.10.2018 Bulletin 2018/40

(21)Application number: 14772239.1

(22)Date of filing:  26.08.2014
(51)International Patent Classification (IPC): 
B32B 15/14(2006.01)
B32B 5/06(2006.01)
B32B 15/04(2006.01)
F01N 13/16(2010.01)
B32B 5/02(2006.01)
B32B 5/26(2006.01)
B32B 15/20(2006.01)
(86)International application number:
PCT/US2014/052707
(87)International publication number:
WO 2015/031361 (05.03.2015 Gazette  2015/09)

(54)

WRAPPABLE MULTI-LAYER HEAT SHIELD

MEHRSCHICHTIGER WICKELBARER HITZESCHILD

ÉCRAN THERMIQUE MULTICOUCHE ENROULABLE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 26.08.2013 US 201361869859 P

(43)Date of publication of application:
06.07.2016 Bulletin 2016/27

(73)Proprietor: Federal-Mogul Powertrain LLC
Southfield, MI 48034 (US)

(72)Inventors:
  • ZHANG, Zhong, Huai
    Pottstown, PA 19465 (US)
  • GAO, Tianqi
    Exton, PA 19341 (US)
  • LUDY, Linwood
    Pottstown, PA 19464 (US)
  • ROWCOTSKY, Daniel
    Dresher, PA 19025 (US)
  • HO, Wai, Kit
    Exton, PA 19341 (US)

(74)Representative: HGF Limited 
4th Floor Merchant Exchange 17-19 Whitworth Street West
Manchester M1 5WG
Manchester M1 5WG (GB)


(56)References cited: : 
WO-A2-2010/028201
US-A1- 2006 070 598
WO-A2-2011/009112
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND OF THE INVENTION


    1. Technical Field



    [0001] This invention relates generally to thermal heat shields, and more particularly to wrappable multilayer thermal heat shields.

    2. Related Art



    [0002] Standards for vehicle emissions are becoming increasing strict in reducing the emission of nitrogen oxide and carbon monoxide. In order to facilitate reducing the emission of these gases, many vehicle applications include selective catalytic reduction (SCR) applications, for example. SCR applications typically incorporate conduits for injecting ammonia or urea solutions into the exhaust pipe upstream of a catalytic converter. The injected solution evaporates and mixes with the exhaust gases to create a chemical reaction that will reduce nitrogen oxide and carbon monoxide emissions, and instead produce nitrogen and water. However, in order for the SCR applications to perform efficiently, it is necessary for the exhaust gases that mix with the injected solution to remain at a maximum high temperature; otherwise, the intended chemical conversion of the nitrogen oxide and carbon monoxide gases is adversely affected and inefficient, thereby resulting in unwanted emissions thereof. Accordingly, it is desirable and important to maintain the exhaust gases along the exhaust system upstream and within the SCR system at a maximum temperature.

    SUMMARY OF THE INVENTION



    [0003] In accordance with one aspect of the invention, a flexible, wrappable multilayered heat shield is provided. The heat shield includes a reflective outermost layer, an innermost layer of high temperature yarn, and an intermediate layer of nonwoven material sandwiched between the outermost and innermost layers. As such, the heat shield is composed of at least three different layers that protect one another in a way that allows each layer to function separately, as intended, and to further function together to provide a synergistic result that allows the heat shield, as a whole, to function as intended.

    [0004] The heat shield is particularly useful as an exhaust system heat shield to facilitate optimal performance of a selective catalytic reduction system (SCR) within the exhaust system by minimizing the thermal losses of the high temperature exhaust gases flowing within the exhaust system. Accordingly, exhaust gases flowing throughout the SCR system of the exhaust system are maintained, by the heat shield, at a maximum temperature within the SCR system, with minimal temperature drop of the exhaust gases from that as first emitted from the engine. As such, an optimal chemical conversion of nitrogen oxide and carbon monoxide within the exhaust gases into nitrogen and water is achieved by the SCR system.

    [0005] The innermost, outermost and intermediate layers of the heat shield can be fixed to one another using a variety of mechanisms, including high temperature adhesives, sewing, and mechanical fasteners, by way of example and without limitation.

    [0006] The heat shield, given it is formed as a generally flat lamination, can be sized and shaped for subsequent wrapping, as desired, such as via die cutting, for example.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0007] These and other aspects, features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description of presently preferred embodiments and best mode, appended claims and accompanying drawings, in which:

    Figure 1 is a partial perspective view of an exhaust system having a multi-layered exhaust system heat shield constructed in accordance with one aspect of the invention; and

    Figure 2 is a partial side view of the multi-layered exhaust system heat shield of Figure 1.


    DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS



    [0008] Referring in more detail to the drawings, Figure 1 illustrates a wrappable, flexible multi-layered heat shield, referred to hereafter as heat shield 10, constructed in accordance with one aspect of the invention that provides desired shielding against thermal and other environment effects, such as to a shielded portion of an exhaust system, represented generally at 12, by way of example and without limitation. The heat shield 10 provides multiple shielding benefits, including, but not limited to, preventing the radiation of the high temperature exhaust gases within the exhaust system 12 to the outside ambient environment E, thus, preventing thermal losses of the high temperature exhaust gases; preventing thermal effects in the outside ambient environment E from reducing the temperature of the high temperature exhaust gases within the exhaust system, including external convection on the exhaust system, and further, preventing outside environment elements, such as fluids, from impacting or otherwise reaching and reducing the temperature exhaust gases within the shielded portion of the exhaust system 12. As such, by providing the desired shielding against thermal losses from the exhaust system 12, a selective catalytic reduction system within the exhaust system 12 can effectively convert high temperature exhaust gases, such as nitrogen oxide and carbon monoxide into nitrogen and water, as intended, to prevent the nitrogen oxide and carbon monoxide from reaching the environment. The heat shield 10 has a wrappable wall 13 that includes an outermost layer 14, an innermost layer 16, and an intermediate layer 18 sandwiched directly between the outermost and innermost layers 14, 16 and in contact therewith. Accordingly, the outermost layer 14 is directly exposed to the outside environment E; the innermost layer 16 is directly exposed to the exhaust system 12, and the intermediate layer 18 is sandwiched between the outermost and innermost layers 14, 16, and thus, it is not in direct contact with the environment E or exhaust system 12.

    [0009] The outermost layer 14 is provided as a solid, impervious reflective layer, and thus, it acts to both reflect radiant heat of the exhaust gases radially inwardly from the outermost layer 14, thereby preventing the heat generated within the exhaust system 12 from escaping, and further, to prevent external environmental effects, such as external convection, from reducing the thermal gradient of the exhaust gases. Further, with the outermost layer 14 being impervious, the outermost layer 14 prevents fluids in the outer environment E from penetrating the heat shield 10, thereby preventing the fluids from reaching the exhaust system 12 and reducing the temperature of the exhaust gases. By way of example, and without limitation, the outermost layer 14 can be provided as a sheet of reflective foil, such as aluminum foil or any other suitable wrappable metal sheet.

    [0010] The innermost layer 16 is provided as a textile fabric formed of interlaced, high temperature yarn, such as via knitting, weaving, braiding, or as a nonwoven material having intertwined high temperature fibers, e.g. basalt, silica, or other high temperature fibers, and as such, can withstand extremely high temperatures, such as 650 degrees Centigrade (°C) continuously, and about 750 °C intermittently. By way of example and without limitation, the inner layer 16 can be constructed having three integrally knit layers, also referred to as a tri-layer knit fabric, including a knit outer layer 20, a knit inner layer 22 and a knit middle layer 24. The middle layer 24 is sandwiched in abutment between the outer and inner layers 20, 22. The three layers 20, 22, 24 are constructed simultaneously in a single knitting operation, thereby providing economic benefits, including, by way of example, minimizing the number of operations, time, knitting machines and floor space. The outer layer 20 has yarns knit with one another via interlooped knit stitches to provide a self-sustaining knit layer, such that the outer layer 20 would not unravel if left to itself, the inner layer 22 has yarns knit with one another via interlooped knit stitches to provide a self-sustaining knit layer, such that the inner layer 22 would not unravel if left to itself, and the middle layer 24 has yarns knit via knit stitches looped about at least some of the yarns of the outer layer 20 and about at least some of the yarns of the inner layer 22, however, the middle layer 24 does not have knit stitches looped amongst itself. Accordingly, the inner layer 16 provides an integrally knit structure having three layers 20, 22, 24 knit stitched together in substantially uniform relation over its entire area such that the three layers 20, 22, 24 of the inner layer 16 are fixed to one another in inseparable fashion. As such, the knit inner layer 16, aside from providing an excellent protective and thermal barrier, has excellent resistance to separation and movement of the layers 20, 22, 24 relative to one another in tension and shear.

    [0011] In manufacture, if knitted, the layers 20, 22, 24 of the innermost layer 16 are knit from any suitable size and type of multifilament and/or monofilament high temperature yarn, including denier and diameter. In addition, any suitable type of knit stitch and density of stitch can be used to construct the layers 20, 22, 24. Accordingly, depending on the functional properties desired, either the same or different types of yarn (e.g., monofilament, multifilament, denier, diameter, color, texture, thermal properties, abrasion resistance, physical properties) can be used to construct each of the layers 20, 22, 24, and the same or different types of knit stitches and stitch densities can be used to construct the outer and inner layers 20, 22, as desired. Accordingly, depending on the intended application, the innermost layer 16 can be customized to best meet the thermal properties desired.

    [0012] The innermost layer 16, if knitted, is preferably knit using a double flatbed knitting machine (not shown), such as discussed in US Patent No. 8,434,333 (referred to as the '333 patent), which is assigned to a common assignee as the instant application, with the '333 patent being incorporated herein by reference in its entirety. While being knit on the double flatbed knitting machine, the outer layer 20 is knit on one bed of the machine and the inner layer 22 is knit on the opposite bed of the machine, wherein the beds converge toward one another. Meanwhile, the middle layer 24 is knit via both beds of the machine simultaneously with the outer and inner layers 20, 22. The outer layer 20 is knit having one selected knit stitch pattern from one yarn, while the inner layer 22 is knit having another knit stitch pattern using another, wherein the respective knit stitch patterns and types of yarn used to construct the outer and inner layers 20, 22 can be the same, or different, depending on the properties desired for the intended application. Accordingly, by way of example and without limitation, the outer and inner layers 20, 22 are constructed from a yarn having high temperature heat resistance, such as from multifilaments of basalt, silica, ceramic, stainless steel, and bi-component yarns wherein both components of the bi-component yarn are high temperature resistant materials, for example.

    [0013] The middle layer 24 of the innermost layer 16, unlike the outer and inner layers 20, 22, is not constructed as a self-sustaining layer. As such, if the outer and inner layers 20, 22 were to be separated from the middle layer 24, the middle layer 24 would not remain as a self-sustaining knit construction, and thus, it would tend to unravel. This is because the yarns of the middle layer 24 are looped about selected yarns of the outer and inner layers 20, 22 using a tuck stitch, and thus, without the yarns of the outer and inner layers 20, 22, the middle layer 24 would come unraveled. As with the outer and inner layers 20, 22, the yarn used to form the middle layer 24 can be selected from any type (monofilament/multifilament), size (denier/diameter) and high temperature material of yarn desired, depending on the requirements of the exhaust application. Accordingly, by way of example and without limitation, the middle layer 24 can be formed from multifilaments of basalt, silica, ceramic, stainless steel, and bi-component yarns wherein both components of the bi-component yarn are high temperature resistant materials. Generally, aside from attaching the outer and inner layers 20, 22 together, the middle layer 24 acts as an additional insulation layer by forming intermediate air pockets between the outer and inner layers 20, 22, thereby providing an enhanced, effective barrier to conduction, convection and radiation.

    [0014] The intermediate layer 18 is provided as a high temperature non-woven material, such as from a layer of fiberglass felt material having glass fibers bonded or locked to together, such as via needled, by way of example and without limitation, which can withstand high temperatures of about 550 °C continuously. It is contemplated that other types of high temperature fibers, including basalt, silica, ceramic, metal, or the like could be used in the construction of the non-woven intermediate layer 18. With the innermost layer 16 being able to withstand even higher temperatures, such as up to 650 °C continuously and 750 °C intermittently, as discussed above, and with the intermediate layer 18 being shielded by the innermost layer 16 from direct exposure to the exhaust system, the intermediate layer 18 is able to be formed with materials having a slightly lower temperature rating and reduced heat capacity relative to the innermost layer 16. This said, with the intermediate layer 18 being a non-woven material, formed of intertwined fibers, numerous micro-pores are formed therein, which act to trap air, and thus, provide an excellent source of insulation to keep heat from escaping. The thickness of the intermediate layer 18 can be adjusted, as desired, to arrive at the insulating "R" value desired for the intended application.

    [0015] Accordingly, the heat shield 10 is composed of at least three different and separate layers 14, 16, 18 that, when fixed together with one another, have a synergy that allows the heat shield 10 to function as intended. Each of the outermost, innermost and intermediate layers 14, 16, 18 protects one another to allow each layer to function as intended, as discussed. The separate layers 14, 16, 18 of the heat shield 10 can be fixed to one another using a variety of mechanisms, including high temperature adhesives, sewing, and mechanical fasteners, by way of example and without limitation. Further, the heat shield 10 can be sized and shaped as desired, such as via die cutting, for example. It should be recognized that with the wall 13 being wrappable, the wall 13 has opposite edges 19, 21 that extend generally parallel with a longitudinal axis 23, such that the opposite edges are wrapped about the axis 13 and either brought into abutment with one another, or overlapped with one another, wherein any suitable fastener 25, such as a metal hose clamp or the like, by way of example and without limitation, can be used to fix the wall 13 of the heat shield 10 in its circumferentially wrapped configuration about the exhaust system 12.

    [0016] Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically described, and that the scope of the invention is defined by any ultimately allowed claims.


    Claims

    1. A protective exhaust system heat shield (10) having a multilayered wrappable wall (13), comprising:

    a heat reflective outermost layer (14) of fluid impervious metal foil;

    an innermost layer (16) of interlaced high temperature yarn selected from the group consisting of basalt, silica, ceramic, and stainless steel; and

    an intermediate layer (18) of high temperature non-woven material sandwiched between said outermost and innermost layers (14, 16).


     
    2. The protective exhaust system heat shield (10) of claim 1 wherein said high temperature non-woven material is fiberglass.
     
    3. The protective exhaust system heat shield (10) of claim 1 wherein said interlaced high temperature yarn of said innermost layer is woven.
     
    4. The protective exhaust system heat shield (10) of claim 1 wherein said interlaced high temperature yarn of said innermost layer (16) is braided.
     
    5. The protective exhaust system heat shield (10) of claim 1 wherein said interlaced high temperature yarn of said innermost layer (16) is knit.
     
    6. The protective exhaust system heat shield of claim 5 wherein said innermost layer (16) includes an outer knit layer (20) overlying an inner knit layer (22).
     
    7. The protective exhaust system heat shield (10) of claim 6 wherein said innermost layer (16) includes a middle knit layer (24) sandwiched in abutment between said outer and inner layers (20, 22).
     
    8. The protective exhaust system heat shield (10) of claim 7 wherein each of said outer and inner knit layers (20, 22) has yarns knit with one another via interlooped knit stiches to provide a self-sustaining knit layer (20, 22) and said middle knit layer (24) has yarns knit via knit stitches looped about at least some of the yarns of the outer knit layer (20) and about at least some of the yarns of the inner knit layer (22) but no knit stitches looped amongst itself.
     
    9. The protective exhaust system heat shield (10) of any preceding claim wherein said heat reflective outermost layer (14) is aluminium foil.
     


    Ansprüche

    1. Schutzabgassystem-Hitzeschild (10) mit einer mehrschichtigen wickelbaren Wand (13), umfassend:
    eine hitzereflektierende äußerste Schicht (14) aus fluidundurchlässiger Metallfolie; eine innerste Schicht (16) aus vernetztem Hochtemperaturgarn, ausgewählt aus der Gruppe, bestehend aus Basalt, Kieselsäure, Keramik und Edelstahl; und eine Zwischenschicht (18) aus Hochtemperaturvliesmaterial, das zwischen den äußersten und den innersten Schichten (14, 16) angeordnet ist.
     
    2. Schutzabgassystem-Hitzeschild (10) nach Anspruch 1, wobei das Hochtemperaturvliesmaterial Glasfaser ist.
     
    3. Schutzabgassystem-Hitzeschild (10) nach Anspruch 1, wobei das vernetzte Hochtemperaturgarn der innersten Schicht gewebt ist.
     
    4. Schutzabgassystem-Hitzeschild (10) nach Anspruch 1, wobei das vernetzte Hochtemperaturgarn der innersten Schicht (16) geflochten ist.
     
    5. Schutzabgassystem-Hitzeschild (10) nach Anspruch 1, wobei das vernetzte Hochtemperaturgarn der innersten Schicht (16) gestrickt ist.
     
    6. Schutzabgassystem-Hitzeschild nach Anspruch 5, wobei die innerste Schicht (16) eine äußere gestrickte Schicht (20) umfasst, die über einer inneren gestrickten Schicht (22) liegt.
     
    7. Schutzabgassystem-Hitzeschild (10) nach Anspruch 6, wobei die innerste Schicht (16) eine mittlere gestrickte Schicht (24) umfasst, die anliegend zwischen den äußeren und inneren Schichten (20, 22) angeordnet ist.
     
    8. Schutzabgassystem-Hitzeschild (10) nach Anspruch 7, wobei jede der äußeren und inneren gestrickten Schichten (20, 22) Garne aufweist, die mit verschlungenen Strickstichen miteinander gestrickt sind, um eine selbsttragende Strickschicht (20, 22) bereitzustellen, und die mittlere Strickschicht (24) Garne aufweist, die um mindestens einige der Garne der äußeren Strickschicht (20) und um mindestens einige der Garne der inneren Strickschicht (22) verschlungen sind, aber keine Strickstiche aufweist, die um sich selbst verschlungen sind.
     
    9. Schutzabgassystem-Hitzeschild (10) nach einem der vorstehenden Ansprüche, wobei die hitzereflektierende äußere Schicht (14) Aluminiumfolie ist.
     


    Revendications

    1. Ecran protecteur thermique pour système d'échappement (10) ayant une paroi multicouche enroulable (13), comprenant :

    une couche extérieure réfléchissant la chaleur (14) en feuille métallique imperméable aux fluides ;

    une couche intérieure (16) de fil entrelacé pour hautes températures sélectionné dans le groupe constitué de: basalte, silice, céramique et acier inoxydable ; et

    une couche intermédiaire (18) de matériau non tissé pour hautes températures interposé entre lesdites couches extérieure et intérieure (14, 16).


     
    2. Ecran protecteur thermique pour système d'échappement (10) selon la revendication 1, dans lequel ledit matériau non tissé pour hautes températures est la fibre de verre.
     
    3. Ecran protecteur thermique pour système d'échappement (10) selon la revendication 1, dans lequel ledit fil entrelacé pour hautes températures de ladite couche intérieure est tissé.
     
    4. Ecran protecteur thermique pour système d'échappement (10) selon la revendication 1, dans lequel ledit fil entrelacé pour hautes températures de ladite couche intérieure (16) est tressé.
     
    5. Ecran protecteur thermique pour système d'échappement (10) selon la revendication 1, dans lequel ledit fil entrelacé pour hautes températures de ladite couche intérieure (16) est maillé.
     
    6. Ecran protecteur thermique pour système d'échappement selon la revendication 5, dans lequel ladite couche intérieure (16) comprend une couche extérieure maillée (20) recouvrant une couche intérieure maillée (22).
     
    7. Ecran protecteur thermique pour système d'échappement (10) selon la revendication 6, dans lequel ladite couche intérieure (16) comporte une couche centrale maillée (24) interposée en butée entre lesdites couches extérieure et intérieure (20, 22).
     
    8. Ecran protecteur thermique pour système d'échappement (10) selon la revendication 7, dans lequel chacune desdites couches maillées extérieure et intérieure (20, 22) a des fils maillés les un avec les autres au moyen de mailles inter-bouclées pour offrir une couche maillée auto-soutenue (20, 22) et ladite couche maillée centrale (24) a des fils maillés au moyen de mailles bouclées autour d'au moins certains des fils de la couche extérieure maillée (20) et autour d'au moins certains des fils de la couche maillée intérieure (22) mais pas de mailles bouclées entre elles.
     
    9. Ecran protecteur thermique pour système d'échappement (10) selon l'une quelconque des revendications précédentes, dans lequel ladite couche extérieure réfléchissant la lumière (14) est de la feuille d'aluminium.
     




    Drawing








    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description