WO2008128789A1

WO2008128789A1 - Heat shield

Info

Publication number: WO2008128789A1
Application number: PCT/EP2008/003331
Authority: WO
Inventors: Georg Egloff; Alexander Gloeggler; Franz Scweiggart
Original assignee: Reinz Dichtungs GmbH
Current assignee: Reinz Dichtungs GmbH
Priority date: 2007-04-24
Filing date: 2008-04-24
Publication date: 2008-10-30
Anticipated expiration: 2009-10-24
Also published as: EP1985439A1

Abstract

The invention relates to a heat shield for shielding an object against heat and/or noise having at least one metal layer and at least one opening, passing through the least one metal layer, for receiving a fastener. A surface structuring is provided regionally on at least one of the surfaces of the least one metal layer, in the area of which the metal layer has a thickness which is greater than its original thickness. The surface structuring is implemented as an annular area extending around the opening of alternating depressions and protrusions, which are situated on at least one family of virtual straight lines running essentially parallel over the entire extent of the surface structuring.

Description

HEAT SHIELD

[0001] The invention relates to a heat shield for shielding an object against heat and/or noise having at least one metal layer and at least one opening, passing through the at least one metal layer, for receiving a fastener. A surface structuring is regionally provided on at least one of the surfaces of the at least one metal layer, in the area of which the metal layer has a thickness which is greater than its original thickness.

[0002] Heat shields of this type are used as noise and/or heat protectors for other components. Heat shields are used in engine compartments of motor vehicles, for example, in the area of the exhaust system in particular, to protect adjacent temperature-sensitive components and assemblies from excessive heating. The heat shields are often simultaneously used as a noise protector. A heat shield frequently comprises two metal layers having a nonmetallic insulation layer situated between them for improving the damping properties. The insulation layer comprises mica, temperature-stable paper, inorganic or organic fiber composite materials, or other suitable insulating materials, for example. The metallic layers typically comprise steel, aluminum-plated steel, or aluminum.

[0003] Frequently, only very little space is available for heat shields upon installation. The heat shields may be damaged because of the vibrations during operation, because they are designed as thin as possible - also in consideration of saving material and weight. There is therefore a demand for a heat shield which, with the least possible material consumption and lowest possible weight, is nonetheless as stable as possible and offers good noise and heat protection.

[0004] A further disadvantage is that heat shields have total thicknesses which deviate from one another as a function of the materials used. These deviations in turn require different fasteners for each heat shield, damping elements for installation between heat shield and the component to which the heat shield is to be fastened, or other parts needed for installation. Therefore, there is a demand for unifying the installation situation of heat shields made of greatly varying starting materials.

[0005] The object of the invention is accordingly to devise a heat shield which does not have the above disadvantages.

[0006] This object is achieved by the heat shield according to Claim 1. Preferred embodiments are described in the subclaims.

[0007] The invention thus relates to a heat shield for shielding an object against heat and/or noise having at least one metal layer and at least one opening, passing through the at least one metal layer, for receiving a fastener. A surface structuring is regionally provided on at least one of the surfaces of the at least one metal layer, in the area of which the metal layer has a thickness which is greater than its original thickness. The surface structuring is implemented as an area, extending annularly around the opening, of alternating depressions and protrusions, which are situated on at least one family of virtual straight lines running essentially parallel over the entire extent of the surface structuring.

[0008] An annular area is to be understood here as an area running continuously around the opening for the fastener, which - except for the fact that it is implemented as closed per se - may have any arbitrary shape. In a simple variant, it may be a circular ring of uniform width, for example. Such a shape suggests itself in particular with circular openings, which then lie in the center of the annular area. However, shapes having eccentric situation of the fastener opening and correspondingly varying width of the structured area around the opening are also possible. With non-round openings, the annular area may run around the opening having uniform width or also having a width varying around the circumference. It is preferable in all cases for the area provided with the surface structuring to extend so closely to the opening that the clamping pressure exerted by the fastener on the metal layer of the heat shield acts on the annular, structured area. If necessary, a fastener such as a screw or a bolt having a head having enlarged contact area or an additional washer may also be used for this purpose. The internal and/or external contour of the annular area of may also be implemented irregularly. The contour curve is expediently oriented to the spatial conditions of the heat shield - above all in regard to the external contour. For example, it may be advisable to select a curve of the external contour in such a manner that the surface structuring does not extend into those areas of the metal layer which are spatially deformed very strongly in the finished heat shield.

[0009] The width of the annular area may thus vary greatly depending on the conditions, such as the shape of the heat shield. The annular area is expediently at least wide enough that it may adequately absorb the clamping forces exerted by the fastener, however. Suitable widths, measured in the radial direction around the opening for the fastener, are typically from 0.4 to 5 cm, preferably 0.6 to 2.5 cm, and particularly 0.8 to 2 cm. In the event of widths varying around the circumference, the width is preferably in the cited ranges at any arbitrary point.

[0010] In the annular area, the metal layer, due to the surface structuring, has a greater thickness than the thickness of the original metal layer, i.e., the planar metal layer before introduction of the surface structuring. The thickness of the metal layer is measured as the distance between two tangential planes which each run parallel to the plane of the non-deformed metal layer and press against the surfaces of the metal layer on diametrically opposite sides. The thickness of the metal layer in the surface-structured area is thus not measured starting from depressions in the surface in any case, but rather from the protrusions present there. If only one of the surfaces of the metal layer has a surface structuring, the distance is thus measured between the plane of the untreated metal layer and a plane which presses against the protrusions on the opposite side of the metal layer. With a metal layer surface-structured on both sides, the distance is measured between two planes which each abut on the protrusions of the corresponding side of the metal layer. The height of the protrusions does not have to be equally tall over the entire annular area. However, because the protrusions extend beyond the untreated surface of the metal layer on at least one side, the thickness of the metal layer in the annular area is greater in any case than the original thickness of the untreated metal layer. Depressions are areas lower than the protrusions, i.e., not necessarily areas which are depressed into the surface of the non-deformed metal layer. Due to the structuring, the thickness of the metal layer is larger than the material thickness of individual points of the structured area.

[0011 ] The annular area provided with the surface structuring on at least one surface of the metal layer in the area around a fastener opening results in increased component rigidity in this area, which has an advantageous effect on the vibration and oscillation behavior of the heat shield. Oscillations transmitted via the fasteners also act especially strongly on the area around the fasteners during the operation of the installed heat shield. The surface structuring in this area effectively prevents damage here.

[0012] By using the surface structuring, material and weight may also be saved, because solely by shaping material out of a thinner metal layer, a greater material thickness may be produced in the annular area without additional material being required for this purpose. The surface structuring may thus be used as a replacement for an additional sheet-metal acting as material reinforcement and thus save costs in production. A heat shield frequently comprises two metal layers having a nonmetallic insulation layer situated between them. The insulation layer is frequently a disturbing factor in the area of the edges of the heat shield or around openings. However, if it is simply left out, the total thickness of the heat shield is reduced in this area, which is often undesirable. However, according to the invention, a thickness compensation may be provided around the fastener openings using the thickened annular area, so that the insulation layer may be left out here.

[0013] A further advantage is that the thickness of the heat shield may be adjusted in the area around the fastener openings in a targeted manner via the height of the surface structuring - largely independently of the material thickness of the unstructured metal layer. This means that a largely uniform installation situation is provided for greatly varying starting materials. Stated concretely, the total thickness of the heat shield remains equal in the area around the fastener openings, while the total thickness may vary in the remaining areas because of the use of different starting materials. Therefore, identical fasteners, damping elements, sliding seats, or other installation parts may be used for different types of heat shields. This significantly simplifies the stocking of such accessories. For example, it is typical to situate a damping element such as a wire cushion around the fastener between the heat shield and the component to which the heat shield is fastened. A sleeve is often also used between fastener and damping element. If the total thickness of the heat shield changes in the area around the fastener, the thickness of the wire cushion and the length of the sleeve must also be changed for a predefined installation situation. This is not necessary in heat shields according to the invention, because differences in the material of the heat shields are compensated for by a corresponding thickening in the area around the fastener openings, so that the total thickness remains unchanged in this area. In a preferred embodiment, the structuring is introduced in such a way that the area around the fastening means is thicker than other areas of the heat shield, even after fastening of the fastening means. [0014] The surface structuring which results in the claimed material thickening comprises depressions and protrusions according to the invention, which are situated alternately to one another and lie on at least one family of straight lines running essentially parallel. These straight lines run continuously over the entire area of the surface structuring in the extension direction of the depressions. This means that depressions and protrusions are distributed very regularly over the entire area occupied by the surface structuring, which makes the production of the surface structuring much simpler, in particular the tools required for this purpose. The family of straight lines running essentially parallel are virtual lines. These lines do extend over the entire area of the surface structuring, but protrusions or depressions do not necessarily have to be present at every point of these lines. For example, the virtual lines may intersect the fastener opening. In such a case, protrusion(s) and/or depression(s) run on a virtual straight line up to the opening, are interrupted there, and then continue again on the opposite side of the opening on the same straight line. The family of straight lines running essentially parallel is thus fundamentally drawn over the entire area of the metal layer, while the protrusions and depressions of the surface structuring follow these lines only in the annular area. The protrusions are each separated from one another by depressions. An essentially parallel course is to be understood as a deviation of at most 5° and in particular at most 2° from parallelism.

[0015] In a first embodiment of the heat shield according to the invention, the protrusions run along only one family of parallel lines. Only a protrusion may be provided on one line and only a depression may be provided on an adjacent line, so that the surface structuring is formed from linearly running depressions situated parallel to one another and having elevated ribs lying between them and has an undulating structure. The depressions are preferably situated having equal width at equal distance to one another and the ribs are correspondingly preferably equally wide. However, different distances between the depressions and different depression and rib widths may also be selected.

[0016] Depressions and protrusions may also alternate in the extension direction of the straight lines. The depressions and protrusions on lines adjacent to one another are preferably each situated offset to one another, so that protrusions and depressions also alternate transversely to the extension direction of the straight lines. [0017] In another implementation of the invention, the depressions are situated along multiple intersecting families of virtual straight lines. The intersecting depressions result in protrusions situated between them, which do not extend continuously over the entire annular area as in the undulating surface structuring, but rather only occupy parts. The intersecting lines preferably form an angle of 30 to 150°, preferably 45 to 135°, especially preferably 80 to 100°, and particularly 90° to one another. In the latter case, a checkerboard pattern of the surface structuring results. The protrusions preferably run on two intersecting families of parallel lines. However, it is also possible for the depressions to run on three families of virtual straight lines, which preferably intersect at an angle of 60°. In all cases, a net-like pattern of the surface structuring results.

[0018] The depressions may also be situated in such a manner that they run on more than three families of virtual straight lines. Multiple shapes of the depressions and the protrusions lying between them are correspondingly possible. The cross-sectional shapes of the depressions and protrusions may also be designed very variably. For example, the cross-section may be implemented as trapezoidal, triangular, rounded, or rectangular in a direction perpendicular to the extension direction of the associated virtual line. For reasons of easier producibility, all depressions expediently have the same cross- section. However, combinations of various cross-sections may also be selected. The depth of the depressions (and/or the height of the protrusions) may also vary. However, identical depths are preferably selected for all depressions here. The depth is understood as the distance between the highest point of the adjacent protrusion and the lowest point of the depression, measured in a direction perpendicular to the plane of the metal layer.

[0019] There are also corresponding variation possibilities for the shape and dimensions of the protrusions in the surface-structured area. The cross-sectional profile of the protrusions may be cap- shaped, rectangular, triangular, or trapezoidal, for example. A preferred shape of a protrusion is the truncated polyhedron, the angles of the base sides to one another preferably being between 70 and 140° and particularly between 90 and 120°. Truncated polyhedrons having a triangular, square, or rectangular base are preferred. The side length on the base of the truncated polyhedron is between 1 and 3 mm, preferably between 1.5 and 2.5 mm, and particularly between 1.6 and 2.0 mm, and the length of the upper edges of the truncated polyhedron is 0.1 to 0.5 mm and preferably 0.2 to 0.3 mm. [0020] Surface structures which result in a significant increase of the rigidity of the metal layer in the annular area in comparison to the unstructured metal layer are preferred in general. The increased rigidity is to prevent bending and twisting of the heat shield in this area as much as possible both during installation and also during operation. Relatively small-part structures are best suitable for this purpose, for example, those in which the distance between the apices of adjacent protrusions are in a range of 1 to 4 mm, preferably 1.5 to 3 mm, and particularly 1.6 to 2.5 mm. If the protrusions have flattened apex areas, the shortest-possible distances between the particular center points of the apex areas are measured. With protrusions of different heights, one measures the distance of the projection of one apex in the plane of the other apex from this other apex.

[0021] While the protrusions may have an equal height over the entire annular area, it is also possible - as noted - for the protrusions to differ in their heights. Such a height profile may be provided as a compensation for a three-dimensional deformation of the heat shield already beginning in the annular area, for example. The height of the protrusions may already be set when the protrusions are worked out of the metal layer, or in that the generated protrusions are flattened or adjusted section- ally or over the entire area or only a part of the surface structuring after their production.

[0022] The surface structure provided according to the invention in the heat shield according to the invention is expediently generated by embossing the metal layer. During the embossing procedure, shear forces occur in the metallic material, which result in strain-hardening and thus increase the rigidity of the metal layer in addition to the effects caused by the structuring. The embossing depth is expediently between 0.4 and 1 mm, preferably 0.65 and 0.9 mm, and particularly between 0.75 and 0.85 mm. It is to be noted that the embossing depth is not identical to the height of the protrusions formed by the embossing. Rather, the latter will typically be less, because the protrusions are embossed out on the opposite side of the metal layer through the metal layer - and correspondingly somewhat reduced in their thickness. Simultaneously, the external contours of the protrusions also blur in comparison to those of the embossing tool because of the "through embossing" (embossing reaching through the layer). When truncated pyramids or prisms or similar shapes were discussed above as the protrusions, these are also to include those shapes having rounded edges.

[0023] Alternatively, the surface structuring may also be generated in a manner different from embossing, for example, by deep drawing, hydroforming, extrusion, or other material displacement, material from the generated depressions being laterally displaced and thus resulting in the protrusions. Independently of the type of the production, the surface structuring is preferably generated in a planar metal layer, which is only subsequently deformed three-dimensionally into the final shape of the heat shield. Because the structured areas are comparatively rigid and poorly deformable, the surface structuring is expediently not provided in those areas which are to be three-dimensionally deformed especially strongly.

[0024] The protrusions of the surface structuring may project beyond the surface of the metal layer on only one side or also on both sides. In the latter case, the protrusions may be situated opposite to the protrusions of the other surface, or the surface structure pattern may be offset in such a manner that protrusions come to rest opposite to depressions of the opposite side. Different surface structure patterns from one another may also be combined with one another on both sides of the metal layer. In addition, it is also fundamentally possible to additionally provide the surface structuring on at least one of the surfaces of the metal layer outside the annular area, if desired even over the entire surface. In general, however, this is not preferable, because this would require too high an embossing force in particular for the embossing of the surface structuring. Through large-area structuring, broadly extending material thickened areas may be achieved while using relatively little starting material and simultaneously having high noise and heat damping. The component rigidity is also higher than in a corresponding starting material without surface structuring.

10025] As the structuring is mainly used in the area of the fastening means, it is exposed partially to the forces of the fastening means and as a consequence, in the area of exposure, its thickness is reduced. With typical bolt forces necessary for fastening a heat shield, the final thickness in the area of the fastening means corresponds to at least 1/4, preferably at last 1/3 of the thickness introduced through the embossment. A fire-aluminated steel sheet of 0.3 mm thickness which contains a bolt hole of 8.7 mm diameter has been structured in such a way that the structuring extended with a diameter of 18 mm around the bolt hole. The structuring resulted in a height of 1.1 mm. A M8 bolt was introduced and fastened with a fastening torque of 22.5 Nm. After release, the structured area still showed a height of 0.52 mm, thus slightly more than 1/3 of the height of the originally structured area. [0026] The invention is suitable both for single-layer and also multi-layered heat shields. Only one of the metal layers may have at least one surface-structured area on one or both surfaces, or the surface- structured annular areas may be provided in more than one metal layer. If the heat shield has more than one fastener opening, all are expediently enclosed by annular areas having a surface structuring. It is possible to distribute annular areas on two adjacent metal layers in such a manner that they supplement one another either in their area and/or in their total height. Adding together the thicknesses of the surface structuring on two adjacent metal layers may be advisable above all if a very great thickness increase is to be achieved in the surface-structured area, but the material required for the material thickening may not be shaped out of a single metal layer. The types of the surface structuring in the various metal layers may be identical to or different from one another. With complementary surface structures of adjacent surfaces, it is possible that they partially engage in one another. However, non-complementary or partially-complementary surface structures are also usable in adjacent surfaces.

[0027] The invention may be applied to greatly varying single-layer or multi-layered heat shields. Three-layered heat shields having two external metal layers and a nonmetallic insulation layer situated between them have already been noted. If the internal surfaces of the metal layers have surface- structured areas, this may have a positive effect on the bonding of the insulation layer, the coupling behavior, and the damping properties. The materials typical until now may be used as the materials. The metallic layers typically comprise steel, aluminum-plated steel, or aluminum. For example, mica, temperature-stable paper, inorganic or organic fiber composite materials, or other suitable insulating materials are used as the insulation layer.

[0028] The invention may fundamentally be applied for all types of heat shields, for example, for those which are used in engine compartments of motor vehicles, in particular in the area of the exhaust system, to protect adjacent temperature-sensitive components and assemblies from excessive heating and/or noise. Concretely, the heat shields may be used, for example, for shielding a catalytic converter or precatalytic converter, a particulate filter, an oxidation catalytic converter, or other components in the area of the exhaust system or a turbocharger. [0029] The invention is described in greater detail in the following with reference to a drawing. The examples shown are only intended for explanation, however; the invention is not restricted thereto. In the schematic figures, in which identical parts are provided with identical reference numerals:

[0030] Figure 1 : shows a first exemplary embodiment of a heat shield according to the invention in a top view;

[0031] Figure 2: shows a top view of a second exemplary embodiment of a heat shield according to the invention;

[0032] Figure 3: shows a partial cross-sectional illustration of the heat shield shown in Figure 2 along line X-X;

[0033] Figure 4: shows a further exemplary embodiment of a heat shield according to the invention in a partial cross-sectional view;

[0034] Figures 5 through 7: show partial cross-sectional views of multi-layered heat shields in an area provided with surface structures;

[0035] Figure 8: shows a further exemplary embodiment of a two-layered heat shield, in which a surface structuring is provided in an area distant from a fastener opening;

[0036] Figure 9: shows a cross-sectional view through a further two-layered heat shield, and

[0037] Figure 10: shows a partial top view of an example of a surface-structured area of a heat shield.

[0038] Figure 1 shows a top view of a first example of a heat shield 1 according to the invention, which may be used in the area of an exhaust system of an internal combustion engine, for example. The upper area of the heat shield 1 in the figure is bent over in the direction toward the observer in relation to the remaining area of the heat shield, which lies essentially in the plane of the paper, to enclose an exhaust pipe or similar component in this manner, for example. The heat shield 1 com- prises two metallic layers 2 and 2', which may be bonded to one another by folding over the outside edges of one of the metal layers around the outside edge 23 onto the other metal layer. A nonmetal- lic insulation layer (not visible in the figure), for example, made of heat-insulating cardboard or mica, may be situated between the metal layers 2 and 2', which each comprise aluminum, for example.

[0039] Two openings 3 are provided for fastening the heat shield 1 to a vehicle body or engine component, in particular to the exhaust manifold. A fastener such as a screw is guided through these openings 3 and fastened to an engine or vehicle body component. A damping element such as a wire cushion may still be attached in the area of one or all of the fasteners in a way known per se between heat shield and engine or vehicle body component to reduce the transmission of vibrations to the heat shield.

[0040] According to the invention, annular areas 6 are provided around the fastener openings 3, which are each provided with a surface structuring. In the heat shield shown in Figure 1, the annular areas 6 are implemented in the shape of circular rings. In contrast, in Figure 2, the annular areas 6 have an approximately square external contour having rounded corners. The heat shield shown in Figure 2 does not otherwise differ from that of Figure 1. The annular areas 6 having the surface structuring each adjoin the circular openings 3 practically without any distance. The openings 3 are each used here for receiving a screw as a fastener.

[0041 ] Figure 3 shows a cross-section along line X-X in Figure 2. A screw 4 is inserted into the opening 3 in such a manner that after the screw is tightened its plate 41 rests on the surface structuring 5 with which the metal layer 2 is provided on its two surfaces 21 and 22. The surface structuring 5 comprises alternating depressions 7 and protrusions 8, which extend over the entire annular area 6 in the form of a continuous wave pattern. All depressions 7 and all protrusions 8 run along parallel lines over the entire annular area 6, as indicated in Figure 2 by the diagonal lines. Protrusions and depressions are solely interrupted by the opening 3. The surface structuring 5 is implemented in such a manner that depressions 7 on one surface (21 or 22) are opposite to protrusions 8 on the other surface (22 or 21) of the metal layer 2. A structure pattern of this type may be obtained by embossing the metal layer between two embossing dies, for example, which are each provided with a wave structure embossing surface. The surface structuring 5 results in a thickening of the annular layer 2 in the annular area 6, compared to the material thickness of the un-embossed metal layer 2. [0042] This layer thickening is illustrated in Figure 4. Figure 4 again shows a cross-sectional illustration of a heat shield according to the invention in the area around a fastener opening 3. This opening is also enclosed by an annular area 6 in which a surface structuring 5 is provided, in the form of a zigzag embossing having depressions 7 and protrusions 8 here, which each have a triangular cross- section. The surface structuring projects beyond the surface 21 of the metal layer 2. The original thickness d of the metal layer 2 is less than the thickness D of the metal layer 2 in the annular area 6. The total thickness DD of the heat shield in the annular area 6 is correspondingly greater than the sum of the thicknesses of the unembossed metal layers 2 and 2'. The second metal layer 2', shown on top in Figure 4, has an area set upright by a bend 10 above the surface structuring 5 of the metal layer 2, to thus provide space for the surface structuring 5. The fastener (not shown here) rests on a smooth contact area, namely the nonstructured metal layer 2', after it has been inserted into the opening 3. Even after fastening of the fastener, the thickness D remains considerably larger than the original material thickness d. In general, at least VA of the thickness introduced, D-d, remains after the fastening of the fastener. Depending on several material properties and the forces necessary for the installation, D will be chosen in such a way that a sufficient thickness even in the installed state is assured.

[0043] Figures 5 and 6 show partial cross-sections through two-layered heat shields in the annular area 6. The metal layers 2 and 2' each have surface structures in this area. The surface structures are different for the metal layers 2 and 2'. In the heat shield according to Figure 5, the surface structures comprise zigzag profiles, the distance A between the apices 81 of adjacent protrusions 8 in the lower metal layer 2 being less than the distance A' between adjacent apices 81' of the metal layer 2'. In the heat shield shown in Figure 6, the surface structuring of the lower metal layer 2 corresponds to that of Figure 5, while the structuring of the metal layer 2' has a smoother undulating profile.

[0044] A three-layered heat shield is shown in Figure 7, in which the surface structuring in the metal layers 2 and 2' essentially corresponds to that of Figure 5. However, an insulation layer 9 is situated between the metal layers 2 and 2' here, which comprises heat-insulating cardboard, for example.

[0045] Figures 8 and 9 show cross-sections through two-layered heat shields, in which surface structures are provided not only in the area around the fastener openings, but rather also in other areas of the heat shield. These may be areas which are subjected to relatively strong mechanical strains during use, like the areas around fastener openings 3. The design shown in Figure 8 essentially corresponds to that of Figure 4, except that no opening is provided in the area of the surface structuring here.

[0046] Figure 9 shows a cross-section through a two-layered heat shield between two edge areas thereof. The metal layer 2 is provided fully over the entire area shown with a surface structuring 5 having alternating depressions 7 and protrusions 8. The metal layer 2', in contrast, has no surface structuring. To fasten the metal layers 2 and 2' to one another, the latter is bent (flanged) around the metal layer 2 in the area of the outer edges 23. The heat shield configuration shown in Figure 9 is typically also three-dimensionally deformed, to adapt its shape to the shape of the object to be shielded.

[0047] Figure 10 shows a partial top view of an area of the metal layer 2 provided with a surface structuring 5. Depressions 7 and protrusions 8 alternate with one another in the area of the surface structuring 5. Depressions and protrusions are situated in such a manner that they run on two families of perpendicularly intersecting virtual lines here, namely the lines V of the first family and the lines V of the second family. In this way, a web-like pattern of depressions 7 results, between which the protrusions 8 are situated. The protrusions 8 have the shape of a truncated pyramid here, having a length L of the bases of the truncated pyramid and a length H of the upper edges. This structural pattern may also be produced by embossing, for example. In this case, however, the structures of the protrusions and depressions and in particular in the edges of the truncated pyramids, which are very sharply contoured here for better illustration, will not appear so clearly pronounced, but rather have a rounded shape.

Claims

CtAIMS

1. A heat shield (1) for shielding an object against heat and/or noise having at least one metal layer

(2) and at least one opening (3), which passes through the at least one metal layer (2), for receiving a fastener (4), in which a surface structuring (5) is provided regionally on at least one of the surfaces (21 , 22) of the at least one metal layer (2), in the area of which the metal layer (2) has a thickness (D), which is greater than its original thickness (d), characterized in that the surface structuring (5) is implemented as an area (6) of alternating depressions (7) and protrusions (8) extending annularly around the opening (3), which are situated on at least one family of virtual straight lines (V) running essentially parallel over the entire extent of the surface structuring (5).

2. The heat shield according to Claim 1 , characterized in that the annular area (6) has a width in the radial direction around the opening

(3) of 0.4 to 5 cm, preferably 0.6 to 2.5 cm, and particularly 0.8 to 2 cm.

3. The heat shield according to Claim 1 or 2, characterized in that depressions (7) and protrusions (8) alternate in the extension direction of the line.

4. The heat shield according to Claim 3, characterized in that the depressions (7) and protrusions (8) on adjacent lines are each situated offset to one another.

5. The heat shield according to Claim 1 or 2, characterized in that the surface structuring (5) is formed by undulating depressions (7) running parallel to one another having elevated ribs (8) lying between them.

6. The heat shield according to one of Claims 1 through 4, characterized in that the surface structuring (5) has depressions (7) which run along at least two intersecting families of virtual straight lines (V, V).

7. The heat shield according to Claim 6, characterized in that the intersecting lines run at an angle of 30 to 150°, preferably 45 to 135°, especially preferably 80 to 100°, and particularly 90° to one another.

8. The heat shield according to Claim 6, characterized in that the depressions (7) run on three families of virtual straight lines which preferably intersect at an angle of 60°.

9. The heat shield according to one of the preceding claims, characterized in that the depressions (7) have a trapezoidal, triangular, rounded, or rectangular cross-section.

10. The heat shield according to one of the preceding claims, characterized in that the protrusions (8) have a cap-shaped, rectangular, triangular, or trapezoidal cross-sectional profile.

11. The heat shield according to Claims 6 through 8, characterized in that the protrusions (8) have the shape of a truncated polyhedron, in particular a truncated pyramid.

12. The heat shield according to one of the preceding claims, characterized in that the height of the protrusions (8) and/or the depth of the depressions (7) changes over the annular area (6).

13. The heat shield according to one of the preceding claims, characterized in that the surface structuring (5) is provided on both surfaces (21, 22) of the at least one metal layer (2).

14. The heat shield according to one of the preceding claims, characterized in that the surface structured area in the installed heat shield has a larger thickness than other areas of the heat shield.

15. The heat shield according to one of the preceding claims, characterized in that the surface structuring (5) is generated by embossing, the embossing depth being between 0.4 and 1 mm, preferably 0.65 and 0.9 mm, and particularly between 0.75 and 0.85 mm.

16. The heat shield according to one of the preceding claims, characterized in that the distance (A) between the apices (81) of adjacent protrusions (8) is in a range from 1 to 4 mm, preferably 1.5 to 3 mm, and particularly 1.6 to 2.5 mm.

17. The heat shield according to one of Claims 11 through 16, characterized in that the side length (L) on the base of the truncated polyhedron is between 1 and 3 mm, preferably between 1.5 and 2.5 mm, and especially preferably between 1.6 and 2.0 mm.

18. The heat shield according to one of Claims 11 through 17, characterized in that the length (H) of the upper edges of the truncated polyhedron is 0.1 to 0.5 mm, preferably 0.2 to 0.3 mm.

19. The heat shield according to one of Claims 14 through 18, characterized in that the surface structuring (5) is additionally provided outside the annular area (6) on at least one of the surfaces (21 , 22) of the least one metal layer (2).

20. The heat shield according to one of the preceding claims, characterized in that it comprises two metal layers (2, 2') having a nonmetallic insulation layer (9) situated between them, the insulation layer preferably being left out in the area of the at least one annular area (6).