AU611386B2

AU611386B2 - Laminar heat shield

Info

Publication number: AU611386B2
Application number: AU67862/87A
Authority: AU
Inventors: Pal Losonci
Original assignee: A4GM ENERGET GEPGYARTO LEANY
Current assignee: A4GM ENERGETIKAI GEPGYARTO LEANYVALLALAT
Priority date: 1986-11-14
Filing date: 1987-01-21
Publication date: 1991-06-13
Anticipated expiration: 2007-01-21
Also published as: PT84200B; EP0289491A1; EP0289491B1; EP0289491A4; PT84200A; CH672828A5; DK471088A; AU6786287A; WO1988003602A1; DE3680793D1; DK471088D0

Description

7 -T i 77 i -1r-1 I1.4 I-T--17-T-r-l pr i I FORM 10 SPRUSON FERGUSON COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int. Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: 0 0 0 oo o o o o o o0 0 00 o o 0 0 0 0 0 0 0 0 0 oo 0o 0 0 o 0 W0 o 00 o o0 o o o t o Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: A4GM Energetikai Gepgyarto Leanyvallalat H-1117 Budapest, XI.Budafoki ut 70., Hungary PAL LOSONCI Spruson Ferguson, Patent Attorneys, Level 33 St Martins Tower, 31 Market Street, Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: "LAMINAR HEAT SHIELD" The following statement is a full description of this invention, including the best method of performing it known to us SBR:JMA:71W SBR:JMA:71W -I U- U i i_ 172 -1-

ABSTRACT

Laminar heat shield for the insulation of duct, pip and tank walls, particularly for the heat insulation of ducts conveying the combustion products of internal combustion engines consist of at least one spiked plate element surrounding the duct-wall, forming an essentially closed space filled with stagnant air, gas or other heat insulating material.

0 0 n 0 00 o no O Go a WO 0 000 oGoO 0 00 ooo t II -1 A x I -A -2 BACKGROUND OF THE INVENTION The invention relates to a laminar heat shield for the insulation of duct, pipe and tank walls, particularly for the heat insulation of ducts conveying combustion products of internal combustion engines, e.g. diesel engines, which consists of at least one spiked plate element surrounding the duct-wall and forming an essentially closed space filled with stagnant air, gas or other heat insulating material.

As known, the exhaust gases leaving the combustion chamber of an internal combustion engine, particularly diesel engines still contain a considerable amount of thermal energy. Consequently these exhaust gases are cooled with water in the ducts of the cylinder head and in the exhaust pipe to keep the heat load of the structural elements containing the ducts to a tolerable level. Though the exhaust pipes of known turbocharged engines are occasionally moderately heat insulated, the exhaust duct of the il 5 cylinder head and the gas- turbine are intensively cooled with water. The heat content of the exhaust gases is considerably dissipated by the cooling S water, thus the amount of thermal energy considered for secondary utilization will be substantially reduced. According to our recognition the secondarily utilizable thermal energy could be substantially increased, if the hot medium conveying ducts were provided with efficient heat insulation enduring the prevailing operational and load conditions, whereby the ducts and the structural units, particularly the casting cases would be 000000protected against excessive heat load, i e. heating to impermissibly high 0 o0~0 temperatures without reducing the high heat content of the emerging exhaust 025 gases with intensive water cooling excluding, or considerably restricting the possibility of secondary utilization. The teachings outlined in the 0000foregoing can be extended to a much wider technical field than that of i nternal combustion engines, since the inevitable measure is found in the 'most diversified thermal -energetic system, that the (still) high heat content of the hot media arising as by-products, especially that of the gases or liquids must be reduced by cooling during their outlet or intermediate storage, in order to avoid the excessive heat load of the structural units permeated by, or in contact with the media of high heat content. It is easy to see that in the majority of such cases, the opportunities and prospects of the secondary utilization could be rhkdpl44E <I 2 3 substantially increased, if the heat load effecting the environment could be kept below the permissible limit values with the suitable, efficient heat insulation of the ducts, especially the duct, pipe and tank walls, while the heat content of the flowing or stored media is preserved in the possibly best way. According to our observations, the main problem lies in the fact, that the geometric configuration of the medium-conveying ducts is generally complicated, having several curves and branchings arranged in the interior of castings and other bodies, whereby they are frequently narrow and inaccessible. Moreover the flowing media in hydraulic machines and especially in internal combustion engines are characterized by pulsating, high internal pressure, hence the ducts, especially the duct-walls are exposed to dynamic load as well. The problem is to develop an efficient heat insulation, or heat shield with small space requirement, which endures o o the previously mentioned dynamic and heat loads for a long time, whereby oV S our recognition outlined in the foregoing would be exploitable in a wide oo range in the practice.

oooo Laminar heat shields with efficient heat insulation properties are o known from several sources. E.g. in the Hungarian patent specification o 00o No. 99721 and air-layered heat and sound insulation system is described, built up with cellular-like elements, where at least one wall of the insulating units is in the direction of the layer thickness of the air cover and serves as a spacer piece ensuring the thickness of the air o layer. This way a multi-layered heat insulating (or sound insulating) o O cover can be applied around the medium conveying pipes. In the DE patent 2 specification No. 2361 036 a laminar heat insulating element is described, S consisting of the assembly of concentric pipes arranged around a pipe conveying the medium. Stagnant air layers are in the cylindrical spaces between the pipe elements fixed with distance pieces in a radial position, while the arrangement of the heat insulating elements prefabricated in the specified length around the different pipe lengths, and the necessary free dilation movement are ensured by the varying length of the heat insulating elements within certain limits with their telescopic construction. In GB-PS 1283 329 such heat insulation is applied mainly around the exterior of the large diameter pipes of atomic power stations, which are built up with multi-layered bank of tubes conslstlng of elementary multicellular rhk/0144E

I~~

-4pipes fitted to each other. Its advantage is the excellent heat insulating effect with the use of relatively small amount of material, further improved by the fact, that only a small proportion of the heat insulating elements are in direct contact with the hot wall-surface.

However the above described laminar heat shield or heat insulators are not suitable for the heat insulation in the vicinity of ducts, or pipes directional changes, elbows, spatial profiles or connections. Likewise they are not applicable for the internal surface heat insulation of relatively narrow ducts, since they are partly large, and partly not pressure-tight and dynamic load-tight, and their assembly requires ample space.

OBJECTS AND SUMMARY OF THE INVENTION The invention is aimed at the construction of a laminar heat shield 0oo free from the shortcomings of the known solutions, and which is extensive utilization suitable for internal heat insulation of medium conveying ducts, particularly with complicated configurations, while ensuring high °o mechanical and heat loadability at the same time.

o°<0 o The objective of the invention is attained with the construction of S000o such laminar heat shield comprising: a first spiked plate which conforms to the surface configuration of the component, the first spiked plate havi.ng aplurallty of needle-like projections extending from a first surface andAextending toward a surface of the component and defining a first closed Insulating space between the spiked plate and the component.

The essential feature of the invention is described in detail with some embodiments given by way of example, with the aid of the enclosed drawings, in which: Fig. 1: cross-sectional detail drawing of a heat shield according to the invention, applied to the inner face of an essentially cylindrical duct, j) Fig. 2-4: cross-sectional detail drawings of an inner wall type heat shields, the function and arrangement of which are the same as those of the one shown in Fig. 1, Fig. 5: cross-sectional view of rolled spiked plates provided with needle-like projections on one side and on both sides,

)Y

A /tV 14 ~rhl 144E i

I

Fig. 6: sectional view of a further heat shield according to the invention, given by way of example, Fig. 7: detail drawing showing the cross section of the heat shield according to Fig. 4, perpendicular to the flow direction of the medium, Fig. 8 and 9: sectional view showing the compensation joints formed in heat shields according to the invention arranged in long, continuous duct-sections.

Figures 1-4 and 6 show the cross-sectional view of the embodiments given by way of example for the laminar heat shield according to the invention, suitable for inside heat insulation of the mainly circular sectional, conveying ducts. In Fig. 1! an essentially cylindrical first spiked plate 1 and second spiked plate 1 are fitted to the internal duct-wall 3 with the aid of a suitable tool. The spiked plates 1 on the I I right side end of the duct are flanges towards the entrance edge and welded to each other. The flange of the first spiked plate 1 in direct contact o with duct-wall 3 Is tightly fitted into the stepped recess machined in the 6° duct-wall 3. The Figure clearly shows that this way heat insulating air S gaps 2 are between the duct-wall 3 and the first spiked plate 1, as well as between the latter one and the inner second spiked plate 1, said air gaps 2 are sealed gas-tight against the hot gaseous medium, especially against the exhaust gas flowing in the duct. The rounding with radius r of the o inner spiked plate 1 at the entrance edge, favourably reduces the flow O resistance.

2S Similar construction is shown in Fig. 2, with the difference, that here the first spiked plate 1 rests directly not upon the duct-walls, but on an insulation spacer 4 fitted into the duct-wall 3, and forming a further heat insulating layer. Such embodiment is shown In Fig. 3, where a lining layer 5 as an additional heat insulating layer is between the spiked diameter of which is shorter than that of the spiked plate 1 welded to the former one along the entrance edge. Here too, an air gap 2 forms a highly effective heat insulating layer between the duct-wall 3 and spiked plate 1. The spiked plates 1 of the heat shields according to the invention shown in Fig. 1-3, are machined with pressing technology from smooth sheet-metal material. The needle-like projections from the plate surface are compressed from sheet-metal with the aid of spiked die.

4714E 1 Il rhKO144E il i :11111- -li~ -6- A heat shield with spiked plate 7 provided with needle-like projections protruding on both sides from the plate surface is shown in Fig. 4. In this construction the spikes of the spiked plate 7 rest partly directly upon the duct-wall 3, and partly on a lining plate 6, and thus a heat insulating air yap 2 is formed on both sides of the spiked plate 7.

The sectional view of spiked plates 9 and 10 produced with rolling is shown in Fig. 5. The spiked plate 9 is provided with needle-like surface elements protruding only on one side from the plate surface, while the spiked plate 10 with needle-like surface elements is protruding on both sides from the plate surface.

A heat shield similar to the one shown in Fig. 4 using rolled spiked plate 10 Is seen in Fig. 6. A heat shield with erosion- and wear resistant surface and improved heat insulation property is obtained, by providing the Inside of lining plate 6 with ceramic coating 8. The heat insulation 15 properties of the laminar heat shields according to the invention can be further improved with conventional methods, such as lapping of the plate S surfaces and suitable selection of the structural materials to be used.

0o The structural material of spiked plates 1, 7, 9, 10 may be heat resistant °ooo steel, but in given case any other structural material, e.g. heat resistant plastic as well. The same applies to the selection of the structural material for the insulation spacer 4 and lining plate 6. Mineral cotton, mineral fibres or foamed plastic can be used for layer insert Since under operational conditions the heat shield applied to the duct wall 3 will inevitably be heated up, It is preferable and occasionally 0 2'S necessary to ensure the possibility of the longitudinal and radial dilation and expansion of the laminar plate elements. For this purpose, according to the method shown in Fig. 7 (that may be the cross section of a heat shield shown in longitudinal section in Fig. the radial expansion joints 11 In the form of a gap between adjacent longitudinal edges are provided for the spiked plate. The radial expansion joints are in the form of either a circumferential gap between spiked plate ends or (b) circumferentially overlapping ends of a spiked plate. The longitudinal expansion joints 11 are shown for the plate elements depicted in Fig. 8, by the longitudinal interruption or gap between the continuity of the circumferential edges of adjacent spiked plates. In order to prevent the I rh AO,44E o CY~ _jii i;_ -7heat shield from rupturing and admitting hot medium into the air gaps, the gas-tight condition of the lining plate is accomplished by building in membrane-type flanges. Naturally this increases the flow resistance, thus it is recommended in cases, when the heat insulation of an already existing duct is realized with the subsequent installation of the heat shield. the construction according to Fig. 9 is preferred in case of ducts designed for the heat insulation with laminar heat shield according to the invention, where constructional space is provided for the gas-tight membrane flange, in an outwardly directed circumferential recess formed in the spiked plate sealing the expansion joint 11 of the lining plate with suitable local outward circumferential bulge of the duct-wall, without narrowing the free flow cross section.

In case of the effective heat insulation of the exhaust gas-conveying ducts of a turbo-diesel engine, using a heat shield according to the 5 invention, the advantages are as follows: ooo The amount of heat admitted from the engine into the turbocharger will be increased by 10-15%, whereby the amount and pressure of the air delivered by the turbocharger into the cylinders of the engine will be o higher. As a result, the specific fuel consumption of the engine will be lower, on the other hand the heat load on the hot parts of the engine will be reduced, consequently the life expectancy of the engine will be extended. The air of higher pressure and amount Injected Into the oOOo cylinders of the engine, result in increased engine power. In addition, DoO the secondary utilization possibilities of the still high heat content of the exhaust gases are more favourable, especially In case of the factory equipment with high engine power, vehicles, e.g. diesel-powered ships. The secondary utilization of the thermal energy may take place for example for auxiliary drives, operation of supplementary equipment, steam generation or Shot water supply.

i rh~/01l 44E

S

y

Claims

1. A laumifiar heat shield for an engine component comprising: a first spiked plate which conforms to the surface configuration of the component, the first spiked plate having a plurality of needle-like ,ri ue projections extending from a first surface and 4 extending toward a surface of the component and definIng a first closed insulating space between the spiked plate and the component.

2. The heat shield of claim 1, wherein a second spiked plate is provided adjacent the first spiked plate, the second spiked plate having a plurality of needle-like projections extending from a first surface and extending toward a second side of the first spiked plate, there being S defined between the first and second spiked plates a second insulating space.

3. The heat shield of either of claims 1 or 2 wherein the 000 needle-like projections of the first spiked plate -est directly on the .0 component. o4. The heat shield of either of claims 1 or 2 wherein the needle-like projections of the first spiked plate rest directly on an insulating spacer which is in direct contact with the component. The heat shield of claim 1 further comprising a lining plate 0' which defines a further closed insulating space between the lining plate 'ot, and the first spiked plate.

6. The heat shield of claim 5, wherein the further closed 0 "K insulating space is filled with an insulating material selected from the group including mineral cotton, mineral fibres or foamed plastic.

7. The heat shield of claim 5 wherein the first spiked plate 000 further comprises additional needle-like projections which extend from a second surface and contact the lining plate.

8. The heat shield of any of claims 5-7 wherein the lining plate is provided with a heat resistant ceramic coating.

9. The heat shield of any of claims 5-8 wherein a side of the lining plate opposite the further closed insulating space is provided with a lapped surface. The heat shield of any of claims 1-9 wherein the engine component is in the form of a cylindrical duct whereby the laminar heat shield is applied to an interior surface of the duct. A rhI 44E 9

11. The heat shield of claim 10 wherein the duct further comprises a terminal circumferential edge, the heat shield terminating at the circumferential edge with a smooth radiused portion which extends about the edge from an innermost surface of the heat shield to the terminal circumferential edge thus providing a smooth duct edge having a reduced resistance to flow.

12. The heat shield of either of claims 10 or 11 wherein a spiked plate is provided with a radial expansion joint in the form of a gap between adjacent longitudinal edges.

13. The heat shield of any of claims 10-12 wherein adjacent spiked plates are provided with a longitudinal expansion joint in the form of a 9 o gap between adjacent circumferential edges. °oSoo 14. The heat shield of cliim 13 wherein the longitudinal expansion a joint further comprises a circumferential membrane-type gas-tight flange oo which extends into the interior of the duct, and whereby the gap between adjacent circumferential edges is located between the flange and the component. The heat shield of claim 7 wherein the heat shield is applied to an interior surface of a duct, the duct having at least one local oO circumferential bulge, the first spiked plate confoming to the bulge and forming a circumferential recess which receives an outwardly directed expansion joint in the form of a membrane-type flange formed in the lining o oo plate.

16. A laminar heat shield substantially as hereinbefore described with reference to the drawing figures. DATED this EIGHTEENTH day of JUNE 1990 A4GM Energetikai Gepgyarto Leanyvallalat Patent Attorneys for the Applicant SPRUSON FERGUSON 1rhK/,1 44E c^".i