DE202012010993U1 - heat shield - Google Patents

Abstract

Heat shield (1) for shielding hot areas of a component with at least one metallic layer (2) and an insulating layer (3) of porous insulating material arranged adjacent to the metallic layer (2), at least in regions, characterized in that the insulating layer (3) on the the surface facing away from the metallic layer (2) has at least one flow channel (10) introduced into the porous insulating material in the form of a groove running away from the metallic layer (2) of the insulating layer (3).

Description

The present invention relates to a heat shield for shielding hot areas of a component. Such heat shields are used for example for shielding hot areas of internal combustion engines, in particular of catalysts, exhaust manifolds, turbochargers and the like or in the battery conditioning. They conventionally have at least one metallic sheet metal layer. In addition to this sheet metal layer, which serves to stabilize the heat shield, an insulation layer of an insulating material, for example a porous material, is typically provided as a further layer.

As far as the insulating layer is not embedded between two sheet metal layers, the insulation layer is applied over the entire surface of the hot component to be shielded, so that it rests on this.

However, the operation of internal combustion engines and the like are subject to load fluctuations that lead to different heat generation over time. For example, immediately after a cold start of an internal combustion engine, it is necessary to bring it to high temperature as quickly as possible in order to minimize emissions and consumption.

For this purpose, an insulation is provided which prevents the heat radiation of the hot or warming component as much as possible. On the other hand, if the internal combustion engine reaches full-load operation, it is necessary to allow the highest possible heat radiation in order to prevent overheating of the hot component or its individual parts. This is especially important where these components are not durable against high temperatures.

Due to the priority of the shielded component overheat protection and the durability of the heat shield, the heat shield assemblies of the prior art often require that they be designed so that the emission reduction at cold start is not taken into account, or only to a small extent. In newer vehicles, especially in hybrid vehicles, however, partial load conditions and operating phases with frequent reboots predominate. For this reason, it is necessary to consider these operating conditions more in the design.

This is where the present invention, which makes it its mission to provide a heat shield available with the excellent insulation can be achieved in all operating conditions and yet sufficient heat dissipation is possible with high heat load. The present invention also relates to an assembly having a heat-generating component on which a heat shield according to the present invention is arranged.

This object is achieved by the heat shield according to claim 1 and the assembly according to claim 19. Advantageous developments of the heat shield according to the invention are given in the dependent claims.

The present invention now solves the above problems by providing a heat shield for shielding hot areas of a component having at least one metallic layer. Adjacent to this metallic layer, a further insulating layer extending substantially parallel to the metallic layer in the layer plane is arranged. The insulating layer consists of porous insulating material or contains this. Advantageously, no further layer is disposed on the surface facing away from the metallic layer of the insulating layer or only layers which are formed according to the contour of the insulating layer, so that the insulating layer comes to rest directly or indirectly on the hot component. The insulating layer now has on its surface, which faces away from the metallic layer, at least one flow channel. This is introduced in the form of a groove in the surface of the insulating layer.

If now the insulating layer over the entire surface on the hot component, so limits the hot component together with the walls of the groove flow channels in the insulating layer. Convection now takes place at high temperature of the hot component via these flow channels between the component and the insulating layer, which dissipates the heat between the component and the insulating layer to the outside, in particular if the component has a high temperature.

According to the invention, therefore, the flow channels are integrated directly in the porous insulation material. By forming a groove, which is closed by the concern of the heat shield on the hot component to the flow channel, it is possible to introduce the flow channels in a simple form in the insulation layer. An advantage of the heat shield according to the invention is now that, for example, when the cold component, the convection between the component and the heat shield is low and so little heat is dissipated. If the component is brought to high temperature, there is a stronger heat dissipation through the integrated flow channels of the heat shield instead.

With regard to the simplest possible production and attachment of the heat shield, it is preferred if this consists of several shells, which are assembled into a heat shield surrounding the component annularly closed. In particular, it is advantageous if the heat shield is constructed from two half-shells, which in turn consist of at least one outer metallic layer and an inner insulating layer. However, it is also possible to combine a larger number of partial shells, in particular three or four partial shells, to form an annularly closed heat shield. For example, the partial shells are connected to one another, in particular on all partial shells at their edge regions, at least in sections, by means of collar-shaped projections which are present around the component after being attached around the component. It is also possible to mount the partial shells individually. A further advantageous variant provides that at least two half shells are connected to one another via a kind of hinge and so the heat shield can be mounted as a whole. These may be hinges made separately, which are connected to the subshells or else to corresponding bending areas, which are provided integrally in the metallic layer of the heat shield, in the latter case, the subshells hang directly together and are not separate components.

In advantageous developments, the flow channels can be open or closed at their inlets and outlets, and thus switched on or off. This allows a regulation of the surface temperature of the hot component. For this purpose, advantageously also a control loop with a temperature sensor, for example on the hot component or the heat shield, in particular on its surface, can be used. To regulate the flow channels actuators can be used or thermosensitive materials that close or open the channels by their temperature-controlled momentum. An opening of the channels is to be provided in particular under full load for improved heat dissipation.

The flow through the flow channels with gas or air is carried out either passively by natural convection, optionally in the case of a vehicle engine or additionally by the driving wind, or by an active blowing of the gases, for example by means of a fan. Furthermore, it is also possible to condition the gas in advance. For this purpose, it can be heated, for example, by means of an electric heater or with the aid of a phase change material. Alternatively, it may be cooled by the vehicle's air conditioning system before passing through the heat shield channels.

Advantageously, the insulating material consists of a non-woven, which is solidified for example by means of a ceramic binder. Such a non-woven can be embossed into a molded part, wherein at the same time the flow channels can be embossed in the side facing away from the metal layer. Possibly. An additional surface treatment can also be carried out, for example by means of a ceramic-based high-temperature adhesive or a ceramic-based high-temperature varnish, to solidify the surface of the insulation layer (skin formation). Such high-temperature adhesives and lacquers may be, for example, materials which tend to form skins at 150 ° C. to 250 ° C.

Particularly suitable as insulating material are glass mats, advantageously of SiO ₂ , Al ₂ O ₃ and / or CaO with binder, expanded mica, basalt rock wool, all types of ceramic compositions, expanded clay or high-temperature foams such as polyimide or melamine. Also sandwich constructions, in particular with at least one of the above materials, are possible.

The formation and arrangement of the flow channels can be done in a variety of ways, these in each case to the thermal requirements, also possibly determined by means of thermography of the hot, shielded component takes place. The flow channels must be adapted to the need for heat dissipation of the hot component and possibly also to the need for heat dissipation in specific areas of the hot component, so-called hot spots. The flow channels may have different patterns on the surface of the insulating layer, for example along the longitudinal extent of the heat shield or transversely thereto, spirally in the form of a single-stage thread or a two-stage winding and / or in the form of several flow channels through which flow in compared with each other in opposite directions. The distances of the flow channels from each other can be adapted to the respective need for heat dissipation, for example in the range of hot spots are more narrow. The cross sections of the flow channels can be kept constant in the course or varied in height or width in the course, so that an adaptation to local conditions is possible. The overall length as well as the pattern of the flow channels, a possible bundling of several flow channels at their inlet or outlet to only one channel and the like can be adapted to the respective requirements. In particular, it is advantageous if the channels in the subshells are made flush with each other, so that the flow of the gas takes place around the entire component. Of course, if only channels are present which extend in the longitudinal direction of the heat shield, this is not necessary.

In particular, in areas of a hot spot, it may be advantageous to widen the width of a channel arranged there, advantageously additionally at the same time but to reduce its height. This then increases the contact surface of the gas and the component and thus the heat transfer to the gas, the heat dissipation is better. The cross-section of the flow channels can also vary greatly in the area of hot spots (also in the flow direction of the gas) (irregular cross sections), so that the gas is put into turbulence, whereby the heat transfer into the gas is improved.

As cross sections for the flow channels 10-500 mm ² , advantageously 30-200 mm ^{2 are} particularly suitable. The distances between individual flow channels can advantageously be 5-100 mm, more advantageously 10-50 mm.

In the case of thread-shaped flow channels, which continue in particular over several partial shells, their pitch may be 25-100 mm, in particular 50 mm. The channel width is advantageously in the range between 3 and 30 mm, advantageously 4 to 20 mm and in particular 8 to 12 mm. For the channel height 2-20 mm, advantageously 5-15 mm and in particular 5-10 mm are particularly suitable.

The cross-sectional shape of the flow channels can be varied and adapted to the respective requirements, for example by using a semicircular, a rectangular or a trapezoidal cross-section, in the case of a trapezoidal cross-section, the longer base side on the side of the hot component or can be arranged opposite. Also omega-shaped cross sections are possible. The arrangement of the flow channels along the hot component is particularly advantageous because this results in a good cooling. However, an oblique guide, advantageously at an angle between 5 and 45 degrees, advantageously 20 degrees, compared to the longitudinal orientation of the component is suitable.

In the following some examples of heat shields according to the invention are given. In all these examples, the same or similar reference numerals are used for the same or similar elements, so that their repetition may be avoided. In the following examples, several elements according to the invention are shown in combination by way of example. However, each individual one of these elements according to the invention can also represent an advantageous development of the present invention independently of the other elements of the respective example.

Show it

1 a heat shield of the prior art;

2 a heat shield according to the invention consisting of two partial shells;

3 and 4 : Top views on heat shields according to the invention;

5 to 7 : Examples of Flow Channel Guides According to the Present Invention; and

8th an inventive heat shield with a hinge mechanism.

1 shows a heat shield 1 with an outer sheet metal layer 2 , In the sheet metal situation 2 embedded and stabilized by this is a largely parallel to the sheet metal layer 2 extending insulation layer 3 arranged from a porous material. The sheet metal situation 2 consists of hot-dip aluminized stainless steel, the insulation layer 3 from a binder-free glass fiber mat. The sheet metal situation 2 and the insulation layer 3 follow in their geometry the geometry of the two adjacent to them components, and thus have a three-dimensional shape with bulges, for example in the areas 40 on. The heat shield 1 according to 1 is combined in practice with a second half-shell and corresponds to the prior art.

2 represents schematically in the form of an exploded view of the structure of the heat shield 1 from two half-shells 1a and 1b The two half shells are intended to be a catalyst 9 to enclose as an adjacent component ring. The half-shells 1a . 1b themselves each consist of a hot-dip aluminized stainless steel bowl 2a . 2 B , in each case an insulation layer 3a . 3b is introduced. The insulation layers 3a . 3b Unlike the insulation layer of the heat shield of the prior art, a glass fiber mat impregnated with a ceramic binder is used to permanently retain its shape. This is especially true for the long-term stability of the channels 10 necessary that the insulation layer on its the component 9 Pull through facing surface.

In 3 is one of the 1 corresponding, but inventive half-shell of a heat shield 1 shown in plan view of the hot component facing surface. According to the invention here are now on the hot component facing side of the heat shield 1 in the material of the insulation layer 3 groove 10a to 10d imprinted by the gas along the hot component between the hot component and the insulation layer 3 can flow. These are the grooves 10a to 10d each at its two ends to the end of the insulation layer 3 thus each have an inlet 5a to 5d and one outlet each 6a to 6d on. The grooves 10a to 10d continue in the mounted state in a complementary half shell, not shown. The grooves 10a to 10d have a substantially semi-circular cross section, wherein the maximum depth of the grooves 8 mm and the maximum width of the grooves is 10 mm.

In 4 is a half shell of a heat shield according to the invention in plan view of the hot component facing surface. Here is the insulation layer 3 highlighted in wavy hatched representation. Again, flow channels are in the form of grooves 10a to 10g embossed in the surface of the insulating layer, which faces the hot component, and which pass through the insulation layer to its edges. The edges 8th the metallic position 2 are in many areas of the interface to the second half-shell collar-shaped outward and thus provide a bearing surface for corresponding collar-shaped projecting edges of the second half-shell. The collar-shaped protruding edges 8th For this purpose, not shown here through holes for fastening means for connecting the beien half shells. Alternatively, the complementary margins 8th be secured by means of clamps or connectors together.

5 shows in the subfigures A to D different possibilities, flow channels 10a to 10d on and in the surface of an insulation layer 3 to arrange. In 5A are a total of four at an angle of about 120 ° relative to the longitudinal axis of a hot component arranged flow channel sections 10a to 10d intended. These run around the component, forming a single continuous channel. This follows from the corresponding sectional drawing in 5B , wherein in the schematic representation, the partial shells are composed. 5B is a simplified representation that does not take into account that the channel sections 10a to 10d not parallel to the paper plane, but as a helical channel oblique to this, as out 5A follows. Accordingly, the inlet and the outlet of the channel are in front of and behind the plane of the paper.

5C also shows spirally around a hot component circulating channels 10a . 10b . 10c and 10d or their sections, whereby multi-stage windings are also provided here. channels 10a and 10c while running in the opposite direction to the extension direction of the channels 10b and 10d ,

In 5D is an arrangement of two spiral around a hot component circulating flow channels 10a and 10b shown. These are offset from each other, so that the windings of the two flow channels 10a and 10b alternately interlaced. The two flow channels are arranged so that their flow takes place in countercurrent.

6 shows in the partial figures A to C, the arrangement of flow channels parallel to the longitudinal axis of a hot component. 6A shows a section of the insulation layer 3 , Wherein in the cutout four flow channels parallel to each other and extending longitudinally straight 10a to 10d can be seen.

In 6B a section through a component assembly is shown, the one in 6A equivalent. The channels 10a to 10d extend in the longitudinal direction (perpendicular to the plane of the drawing 6B ) parallel to each other. It is in 6B to recognize that next to the channels 10a to 10d further channels are provided, wherein the heat shield 1 the hot component 9 completely surrounds and thereby isolated or cooled.

In 6C is an arrangement of flow channels 10a to 10e represented to a large extent those in 6A and 6B corresponds, but the channels 10a to 10e at an angle of about 20 degrees to the longitudinal axis of the hot component 9 (in 6C horizontally).

Also in 7 is a corresponding section of an insulation layer 3 shown, in which case again the flow channels 10a to 10h at an angle to the longitudinal axis (in 7 extending horizontally) of the hot component. In addition, the cross-section of the flow channels 10a to 10h not constant among each other. In particular, the cross section of the flow channels 10c to 10f less than that of the channels 10a . 10b and 10g , Furthermore, the distance between the channels 10c to 10f smaller and thus the density of the channels in this area higher than for the channels 10a . 10b . 10g and 10h , Such an arrangement and configuration of the flow channels can be selected for example in the region of a hot spot of the hot component to be shielded, wherein the hot spot of the channels 10c to 10f is covered. As a result, a better cooling of the hot spot is achieved because in the area of the hot spot, the flow velocity in the channels 10c to 10f is high and continues to increase the density of the channels.

8th illustrates another embodiment of a heat shield according to the invention 1 , As in 2 exists the heat shield 1 from two half-shells 1a . 1b but here's a hinge 7 are connected. The half-shells 1a . 1b are as previously described each of an outer metal layer 2a . 2 B and in each case an inner insulation layer 3a . 3b built up. The thickness ratios of sheet metal layer 2a . 2 B and isolation situation 3a . 3b are not to scale. In the isolation layers 3a . 3b run semicircular profiled channels 10a to 10d spiraling into or out of the plane of the paper. Be the two half-shells 1a . 1b of the heat shield 1 by means of the hinge 7 around the component to be shielded 9 Folded around, meet the ends of the channels 10a . 10b in the half shell 1a to her sequels not seen here in the other half-shell 1b and thus form a continuous spiral. The protruding edges 8th the two half-shells 2a . 2 B meet when folding at least partially flat on each other and can be connected to each other with fasteners, such as clips or screws.

Claims (19)

Heat shield ( 1 ) for shielding hot areas of a component with at least one metallic layer ( 2 ) and one to the metallic layer ( 2 ) at least partially adjacent insulating layer ( 3 ) made of porous insulating material, characterized in that the insulating layer ( 3 ) on the metallic layer ( 2 ) facing away from the surface at least one introduced into the porous insulating material flow channel ( 10 ) in the form of a metallic layer ( 2 ) facing away from the insulating layer ( 3 ) has running groove. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the insulating layer ( 3 ) extends over at least 50%, advantageously at least 80%, advantageously at least 90% of the planar extent of the metallic layer. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the heat shield consists of several partial shells ( 1a . 1b ), which in the installed state is a component ( 9 ) surrounded by a ring. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the metallic layer consists of steel sheet, aluminized steel sheet, in particular hot-dip aluminized and / or aluplattiertem steel sheet, or the like, in particular in the form of a smooth sheet or at least partially noppalierten sheet, or contains this. Heat shield ( 1 ) according to any one of the preceding claims, characterized in that the insulating material is a non-woven, advantageously a Vliess solidified by means of a ceramic binder and / or a Vliess embossed into a molded part. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the insulating material a Glasvliess, advantageously of SiO ₂ , Al ₂ O ₃ and CaO, or expanded mica or basalt rock wool or a ceramic mass or expanded clay or a high-temperature foam, advantageously of polyimide or melamine , Heat shield ( 1 ) according to one of the preceding claims, characterized in that the insulating layer is at least partially surface-treated to form a solidified surface, for example, solidified with a ceramic-based high temperature adhesive or other binder is coated with a ceramic-based high temperature paint or other binder is impregnated and / or by Pressing under elevated temperature. Heat shield ( 1 ) according to one of the preceding claims, characterized in that one or more flow channels, in particular two flow channels, spaced from each other extending on the surface of the insulating layer are formed. Heat shield ( 1 ) according to the preceding claim, characterized in that the distance between individual sections of a flow channel and / or the distance of the plurality of flow channels from each other in areas with higher thermal load of the heat shield is lower than in areas with lower thermal stress. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the housing has a flat, self-contained, hollow shape for receiving the hot component outer shape. Heat shield ( 1 ) according to the preceding claim, characterized in that one or more flow channels, in particular two flow channels, are formed, which are spaced apart on the surface of the insulating layer, the cavity formed spirally once or several times circumferentially. Heat shield ( 1 ) according to the preceding claim, characterized in that the housing is closed so that at least a part of the flow channels at the interface at which the housing is closed, merges flush with each other. Heat shield according to one of the two preceding claims, characterized in that at least two mutually independent spirally encircling flow channels are formed. Heat shield according to one of claims 11 to 13, characterized in that the at least one spirally encircling flow channel in the main direction of the spiral has a varying distance between the spiral turns. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the groove forming a flow channel has a rectangular or square or trapezoidal or advantageously semicircular cross section on at least part of its longitudinal extent. Heat shield ( 1 ) according to one of the preceding claims, characterized in that the groove forming a flow channel on at least part of its longitudinal extent has a tapered, advantageously conically tapering, cross-section and / or a cross-sectionally larger and smaller along the groove cross-section. Heat shield ( 1 ) according to one of the preceding claims, characterized in that it further comprises: at least one device for actively or passively closing and / or venting at least one of the flow channels. Heat shield ( 1 ) according to one of the preceding claims for the shielding of components, in particular components of an internal combustion engine, in particular the exhaust line, in particular the exhaust manifold or the unit for exhaust aftertreatment, the unit for engine charging and / or of heat exchangers, for example. Heat exchangers for heating transmission oil, in the interior auxiliary heating and / or in battery conditioning. Assembly with a component and a heat shield ( 1 ) according to one of the preceding claims, characterized in that the heat shield on the component ( 9 ) is arranged such that the insulating layer with its surface facing away from the metallic layer at least partially rests on the surface of the component and in these areas at least partially form the surface of the component with the grooves of the flow channels together flow paths for a fluid or limit.

Images