WO2016016281A1

WO2016016281A1 - Covering cap for an access hole in a heat shield and a fastening element positionable in the access hole, and heat shield with a covering cap

Info

Publication number: WO2016016281A1
Application number: PCT/EP2015/067331
Authority: WO
Inventors: Andreas Böttcher; Shahrzad Juhnke; Boris Ferdinand Kock; Tobias Krieger; Patrick Lapp; Andreas Mann; Kai-Uwe Schildmacher; Daniel Vogtmann
Original assignee: Siemens Aktiengesellschaft
Priority date: 2014-07-31
Filing date: 2015-07-29
Publication date: 2016-02-04
Also published as: DE102014215034A1

Abstract

The invention relates to a covering cap (6) for an access hole (3) in a heat shield (1) and a fastening element (4) positionable in the access hole (3) for fastening the heat shield (1) to a wall, comprising a cap body (7) which is configured to close the access hole (3) at least partially and has a thermal barrier coating (10) on the upper side thereof, and fixing means which are configured to detachably fix the cap body (7), in particular by clamping, to the access hole (3) and/or to the fastening element (4). The invention additionally relates to a heat shield (1) having a thermal barrier coating (2) on the upper side thereof and having an in particular central access hole (3), in which, in the mounted state, a fastening element (4) is positioned for fastening the heat shield (1) to a wall, and having a covering cap (6) of the previously described type which is detachably fixed, in particular by clamping, to the access hole (3) and/or to the fastening element (4).

Description

description

Cover cap for a penetration hole in a heat shield and a fixing element that can be positioned in the penetration hole, as well as a heat shield with a cover cap

The invention relates to a cap for a

Penetration hole in a heat shield and one in the

Through hole positionable fixing for Fixie ^¬ tion of the heat shield on a wall. Moreover, the invention relates to a heat shield with a thermal barrier coating on its upper side and with a particular zent ^¬ ral piercing hole in which a fixing element for fixing the heat shield is positioned on a wall in the assembled state.

Heat shields (English: metallic heat shield - MHS) of the type mentioned ^¬ are known from the prior art. These are, for example in combustion chambers, in particular in gas turbine combustors ^¬, for use to protect arranged in the combustion chamber components and their wall in front of the hot gas and excessive heat radiation. For this purpose, the heat shields are provided on their upper side with a thermal barrier coating (TBC) and fastened with suitable fixing elements, for example screws, to the walls or components to be protected in such a way that their upper side provided with the thermal barrier coating penetrates into the Combustion chamber points. For the attachment to the heat shields is usually a particular central

Through hole provided for the fixing. This is then in a conventional manner by the

Passage opening screwed to the component or wall to be protected.

Since a heat shield when it is exposed to high temperature in a combustion chamber of more than 1000 ° C, expands ^¬, is a single, centrally provided in this Through hole advantage. In this case, the shield can extend uniformly in all directions, without material loads occurring, in particular, in the case of the thermal expansion of a shield fixed to two or more suspension points. In addition, the installation cost when the heat shields are attached only by means of a fixing element, low.

During operation of the combustion chamber, the heat shields are actively cooled to withstand the extreme operating conditions in the combustion chamber. This is done by passing cooling air from the "cold" underside facing the wall of the combustion chamber to the top in the combustion chamber via openings provided in the heat shield conditions is exposed in the combustion chamber, is also actively cooled this normally. here ^¬ to channels for directing cooling air are provided in the fixing.

Heat shields of the aforementioned type have been proven to protect the wall in the combustion chamber and components provided therein from the high temperatures. However, efforts are being made to operate the combustion chambers under ever more extreme conditions, above all to realize ever higher temperatures. Keeps the heat shield, in particular the fi ^¬ xierelement not stand these conditions, a si ^¬ insurers operation of the combustion chamber is no longer guaranteed. Ins ^¬ particular can the fixing when it is formed into strong comparable, a weak spot and the heat shield may become detached from the wall.

Based on this prior art, it is an object of the present invention to provide a device which ensures the safe operation of a system, in particular a

Combustion chamber allows, in which heat shields of the type pre ^¬ called are used. This object is achieved by a cap for a penetration hole in a heat shield and in the

Through hole positionable fixing for Fixie ^¬ tion of the heat shield on a wall, comprising

- A cap body, which is designed to the

At least partially closed Durchgriffsbohrung and has on its upper side a thermal barrier coating, and

- Fixing means which are adapted to the cap ^¬ body releasably, in particular clamping on the

Through hole and / or attach to the fixing.

The basic idea of the present invention is in other words, is to protect the break-through hole, and thus the fixing member positioned in this specifically by means of a fiction, ^¬ configured according to the cap.

The cap according to the invention comprises a cap body, which is designed to at least partially close the penetration hole. This means that the Kappenkör ^¬ is via suitable constantly cover the penetration hole partially or fully, so that the arranged in this fixing ^¬ element in front of the hot gas and the radiant heat in the combustion chamber is protected. The cap body can for this purpose fundamentally ^¬ additionally have any shape that is suitable to cover the penetration hole in the above-mentioned type. The cap body can be designed, for example, in such a way that it closes the through-hole completely, in particular flush. Alternatively, the cap body can only partially close the penetration hole. Thus, according to one embodiment, openings are provided in the upper wall of the cap body. The openings can be, for example, dimensioned such that the cap body completely closes the through hole ^¬ handle substantially. If the through-hole is not completely closed, but for example openings are provided in the cap body, then cooling air can be guided through the openings particularly well in the direction of the combustion chamber in order to actively cool the penetration hole and the fixing element by means of cooling air.

The openings may for example be provided in the upper wall of the cap body. In this way, the openings can also serve a particularly convenient removal of the cap of the invention from the penetration hole. In the openings and a suitable tool can be introduced to lift the cap with the help of the penetration hole.

In order for cooling air to flow through a through-hole which is closed by a cover cap according to the invention and can enter the combustion chamber, openings of the aforementioned type may be provided, but these are not required. In general, even with a complete closing of the through-hole by means of the cap body - be ^¬ already due to manufacturing tolerances - gap areas between the cap body and the wall of the

Through hole, through which cooling air can flow.

To protect the fixing from the high temperatures in the combustion chamber, the cap according to the invention further comprises a thermal barrier coating. This is provided on the upper side of the cap body, ie on the side of the upper wall of the cap body, which points in the direction of the combustion chamber, when the cap on the through-hole

and / or the fixing element is attached. In a further development of the invention, the thermal barrier coating may be designed to withstand temperatures of more than 1000 ° C and this may include in particular ceramic materials.

Thermal barrier coatings (TBCs) are known to be able to withstand the temperature of high-temperature applications. lying down material in a range in which the material still has sufficient strength. The thermal barrier coating, which can withstand, for example, temperatures of more than 1000 ° C. and more, ensures, for example, that a metal component coated with the latter is kept in the combustion chamber at a temperature of less than 800 ° C.

The cap according to the invention further comprises fastening means, via which the cap body can be detachably, in particular by clamping, attached to the penetration bore and / or to the fixing element. In this case can be used which are suitable to fix the Cape ^¬ pen body, for example, clamping, locking or sticking or other means either at the penetration hole and / or to the fixing any Fixed To ^¬ restriction means. The releasable attachment ge ^¬ ensured is that the attached cap can be removed from the penetration hole again. This is for example required for maintenance, especially if the heat shield must be, for example vorü ^¬ mountains starting away for repair or replacement.

To fix the idea, an invention designed according to the cap on the penetration hole or the fixing, provides a surprisingly simple, inexpensive and mon ^¬ day friendly solution for the above object. As a result of the use of the covering cap according to the invention, the fixing element positioned in the through-hole is efficiently protected from the high temperatures in the combustion chamber. The fixing, which for example a

Are screw is made of metal, can be so maintained with comparatively simp ^¬ chen means to a temperature at which it still has sufficient strength. As a result, the heat shield is particularly securely fixed, which also ensures safe operation of the combustion chamber.

Since the cap according to the invention can be easily attached to the fixing ^¬ element, the assembly or De- mounting effort of the heat shield practically not increased. The cap can be retrofitted in a very simple way to exist ^¬ the heat shields. In this case, the usual standard parts can continue to be used.

Using the cap according to the invention, in particular, an active cooling of the fixing element by means of cooling air can be significantly reduced or - depending on the application - completely dispensed with. Thus, the cooling air mass flow entering the combustion chamber is significantly reduced compared with the prior art, which has a positive effect on the emission values. Dispensing with the active cooling of the fixing, pro ^¬ production costs can be reduced to a considerable extent, as usual fixing elements, such as screws, ver ^¬ applies without special cooling air ducts can be.

Also, when using the cap according to the invention high temperatures can be realized in the combustion chamber, without causing the risk of damage to the fixing increases. In particular, higher mass flows in the combustion chamber can be realized.

An embodiment of the cap according to the invention is characterized by the fact that the cap body is formed sleeve-shaped and in particular a plate-shaped round upper wall and one of the upper wall down

having projecting annular ridge.

A sleeve-shaped Enriched cap body is well suited to be ge ^¬ inserted into a penetration hole of a heat shield and engage over the fixing therein protective. The cap body comprises in an advantageous embodiment a plate-shaped circular top wall and an upper wall projecting from the downward annular ridge, so the shape of which is adapted in particular geeig ^¬ neter manner to the circular usually penetration bore. It can further be provided that the diameter of the annular ridge is smaller than the diameter of the upper wall, and in particular a tapered from the outer edge of the upper wall to the outside of the annular ridge portion is provided as an abutment of the cap body to an end portion the penetration hole is used. A region that tapers in this way can, for example, provide a suitable, in particular precisely fitting, abutment surface for a penetration bore, which in its upper end region, that is to say the combustion chamber, has an edge which is rounded in a quarter-circle, for example.

Furthermore, the fastening means may take a circlip environmentally which surrounds the cap body at least partially on the outside and in particular at least has a portion ^¬ which projects through at least one corresponding lateral opening in the cap body inwards. A locking ring is a suitable means to allow a clamping attachment of the cap on the penetration hole and / or on the fixing element.

The retaining ring is expediently designed to be open, so that it can be easily spread elastically in order to put it on the cap. It also consists of an elas ^¬ table resilient material, such as metal, in particular of a spring steel.

The circlip may have a half- or three-quarter circular section and a V-shaped inwardly bent section at each of its two ends. Such an open locking ring can be obtained, for example, by bending a wire of a suitable material into a corresponding shape.

A circlip made of a resiliently elastic material surrounds a sleeve-shaped cap body on the outside and has portions which pass through lateral openings in the Inner space of the cap body protrude, the inwardly projecting end portions of the fixing can frictionally in An ^¬ position, so that the cap is clamped to the fixing.

A further embodiment of the cap according to the invention is further distinguished by the fact that it has an open towards the bottom receptacle, which is ^{adapted to} ei ^¬ NEN end portion of the fixing, in particular the head of a screw, and in particular in the receptacle down protruding projection is provided. The receptacle can be configured such that it engages around the end region of the fixing element in a form-fitting manner or with play. The cover cap can then be attached particularly comfortably to the fixing element.

A protrusion is expedient if a fixing element for a ^¬ set comes, a recess of corresponding shape is provided in its upper end portion, so that when the Cape is pen body fixed to the penetration hole and / or on the fixing member between the projection and the Vertie ^¬ tion at least one particular annular channel for Füh ^¬ tion of cooling air is defined. The projection may be, for example, conical or semi-circular in ^¬ .

If a securing ring serves as a fastening means in the embodiment, this can protrude in particular through lateral openings in the region of the receptacle inwardly. A further advantageous embodiment of the invention is characterized in that guide means are provided for guiding cooling air, which in particular comprise at least ei ^¬ nen extending through the wall of the cap body channel. This embodiment allows active cooling of the cap body of the cap according to the invention. The channel or channels can be oriented arbitrarily. Closes the cap according to the invention the

Penetration opening in the heat shield completely, so connected the channels for guiding cooling air in particular ver ^¬ closed interior of the through-hole below the cap with the lying before the top of the cover ^¬ area, ie with the interior of the combustion chamber.

If guide means are provided for guiding cooling air and if the covering cap according to the invention has a downwardly open receptacle for the end region of the fixing element, at least one channel can extend in particular from the interior of the receptacle to the outside of the cap body.

It can further be provided that extends at least one channel at least substantially vertically through the upper Wan ^¬ tion of the cap body and / or at least one channel ^{¬ at} least substantially horizontally through a side wall of the cap body. By means of one or more channels in the upper wall of the cap body, for example, cooling air can be guided from the region under the covering cap into the region above it.

Cooling air can also be conducted into the space extending laterally around the cap body through one or more channels in side walls of the body, in particular into the space between the inner wall of the through-hole and the lateral outer wall of the cap body.

The means for guiding cooling air may also comprise one or more grooves, which are provided for example on the outside of the cap body. The cap body can then be formed, for example, such that its Außenwan ^¬ tion in the groove or the grooves in abutment against the inner wall of the through-hole and so the grooves are closed by the inner wall of the penetration hole. In this way channels are used to guide

Cooling air received.

A further embodiment of the present invention is characterized in that the cap body of the invention To cap according to the invention made of metal and / or ceramic is made. These materials are particularly useful because they can withstand relatively ho ^¬ hen temperatures for applications in the high temperature range.

The above object is further achieved by a heat shield with a thermal barrier coating on its upper side and with a particular central through-hole, in which a fixing element for fixing the heat shield is positioned on a wall in the assembled state, and with a cap according to the invention, at the Durchgriffsbohrung and / or the fixing element detachably, in particular by clamping be ^¬ consolidates. In this case, the cap, for example, on the

Through hole and / or attached to the fixing element sin that the top of the cap body is in a plane with the top of the heat shield. Thus, the opening in the heat shield, which must be present in the form of Durchflußsbohrung for the fixing element, so closed by the cover ^¬ cap that a heat shield with a flat, closed top is obtained.

If a cap according to the invention is used, it can be dispensed with entirely, active cooling of the components, in particular the fixing element and / or the wall of the through hole ^¬ handle and / or of the cap body. However, depending on the application, especially depending on the operating temperature to be achieved in the combustion chamber, it may be advantageous if, in addition, active cooling of one or more of these components takes place. Therefore, in a further development, as an alternative or in addition to the means for guiding cooling air provided on the covering cap according to the invention, it is also possible to provide means for admitting or guiding cooling air to the through-hole and / or the fixing element. Active cooling of penetration hole, cap body and fixing allows a particularly safe operation especially in the very high Tem ^¬ tures. It is ensured by the use of the cap according to the invention that the mass flow of cooling air, which is required to maintain predetermined temperatures of the individual components, is basically reduced compared to an operation without the cap. Accordingly, means are provided for the cooling in development of the heat shield according to the invention to admit cooling air into the through-hole, wherein the means comprise in particular channels which extend through a side wall and / or a bottom wall of the through-hole.

A further embodiment of the heat shield according to the invention is characterized in that a channel for guiding is in the fixing member provided at least by cooling air, wherein in particular there is provided a to mentes in the longitudinal direction of the Fixierele- extending supply channel, from which in particular at least a branch duct, in particular tan ^¬ gential or radial, branches off.

The feed channel can extend over the entire length of the fixing element, for example over the entire length of a screw used for use, and open into an inlet and outlet opening in the upper and lower end regions of the fixing element. In this case can

Cooling air are introduced from below into the fixing, this flow through in the longitudinal direction and exit at the top again. Furthermore, one or more branch channels can branch off from the supply channel which extends in the longitudinal direction. These can be provided at any point on the fixing element, in particular at its lower or upper end region, and extend tangentially or radially outward from the supply channel. Channels extending tangentially to the feed channel, which open into the lower end region of the fixing element, allow, in particular, a tangential supply of cooling air into the feed channel. The tangential geometry can be as ^¬ achieved in a strudeiförmige airflow.

Alternatively or in addition to a tangential air supply, e.g. a swirl plate may be provided in a supply channel extending in the longitudinal direction through the fixing element.

For cooling, it may further be provided in an advantageous embodiment that the cap body is formed such that between the cap body and the fixing element and / or between the cap body and the penetration hole at least one channel is defined for guiding cooling air when the cap body at the penetration hole and / or attached to the fixing element. According to this embodiment, the cap body is formed so that when this is fixed in the intended position on the penetration hole and / or the fixing element, between this and the ^¬ handle bore and / or between this and the fixing a gap or more spaces free stay. These spaces are used according to the embodiment specifically as channels for the guidance of cooling air. Between cap body and penetration hole and / or fixing, for example, tubular or annular channels can be out ^¬ forms.

In this case, further a downwardly open receptacle on the Ab ^¬ over-cap may be provided which is adapted to receive at least the upper end portion of the fixing member and it may in particular between the inner wall of the receptacle and the outer wall of the fixing element at least one channel authorized to bring ^¬ tion of cooling air be defined when the cap body is attached to the penetration hole and / or on the fixing element. In a further development of the heat shield according to the invention may also be provided in the upper end portion of the fixing element a recess and in particular in the receptacle downwardly projecting projection be provided, which is complementary to the recess formed such that zwi ^¬ tween the projection and the Well at least one particular annular channel for guiding cooling air is defined when the cap body at the penetration hole

and / or attached to the fixing element.

The recess may be, for example, conical. If a projection is also provided, in an advantageous embodiment this may likewise be conical, so that a conical annular channel is defined between the recess and the projection when the cap body engages the through-hole

and / or attached to the fixing element. By koni ^¬ 's annular channel cooling air can be performed in a particularly simple manner, for example, from the center of the fixing obliquely upwards in the direction of the top of the cap body. In the center of the fixing then a feed channel can be seen before ^¬ , which opens into the pointed end portion of the conical annular channel.

The depression, which is provided, for example, in the head of a screw serving as a fixing element, can be designed, for example, as a fan-shaped bore.

As an alternative to the conical shape, the projection and the complementarily formed recess may, for example, also be semicircular, so that a channel in the form of a hemispherical shell is defined between them. Other shapes are also possible, for example, can be cylindrical or elliptical Before ^¬ jump and recess, in which case a channel corresponding shape between WAIVED is defined.

Are a projection and a complementary depression vorgese ^¬ hen, which define a channel in which a in Longitudinal direction of the fixing element extending feed channel, so it is particularly advantageous if the cooling air is guided with swirl in the feed channel. This may play a swirl vane may be provided in the supply passage at ^¬ or is cooling air tangentially in particular ^¬ sondere introduced into the feed channel, in its lower end portion.

In a further embodiment of the heat shield according to the invention is further provided that at the

Through hole and / or on the cap body fastening means are provided, via which the cap can be releasably, in particular by clamping, attached to the through-hole and / or on the fixing, wherein the fastening ^¬ supply means in particular comprise a securing ring.

Fastening means by which the cap body in particular ^¬ sondere can be clampingly attached to the penetration hole and / or to the fixing member releasably may be provided to the cap body itself. According to the aforementioned embodiment, it is alternatively or additionally possible that fastening means are also provided on the through-hole. For example, the fastening means provided on the through-hole may comprise a securing ring, which may then be arranged in a recess provided in the through-hole. , The retaining ring also in this embodiment, inwardly projecting portions on, they can be clampingly ge ^¬ into contact with the cap body when the latter is positioned in the penetration hole. For example, openings, grooves or the like can then be provided on the cap body, into which a degenerating part of a securing ring can engage. Alternatively or in addition to a retaining ring, other fastening means may also be provided, which allow, for example, a latching or clamping attachment.

In an analogous manner, a further groove is provided in a further development of the invention in the upper end region of the fixing means, in the fastening means, in particular a retaining ring, can intervene. The fastening means may alternatively or in addition, that they come into contact with the cap body frictionally also to the fixing member in at ^¬ position come. A locking ring used as a particularly secure fit of the cap on the fixing can it be aimed ^¬ when a groove is provided on that, which is engaged by the locking ring.

In a concrete constructive configuration, it may be provided that the cap body is sleeve-shaped, wherein the retaining ring at least partially surrounds the cap body on the outside and protrudes inwardly through lateral openings in the cap body, in particular in the region of a receptacle provided on the cap body and is formed, at least the upper end portion of the fixing on ^¬ increase, such that the securing ring for fixing the cap is non-positively engageable in abutment with the fixing, in particular in the region of the groove. Finally, it can be provided that the outer contour of the cap body is adapted to the inner contour of the through-hole in its upper end region. Thus, the cap body fits exactly into the end area of the access opening, sits well in this and can protect the fixing element particularly efficient.

In a further development of the heat shield of the present invention the cover is further configured such that they supply the upper ^¬ side of the heat shield in the area of the penetration bore least essentially closes flush.

With regard to further advantageous embodiments of the invention, reference is made to the dependent claims and the following description of an embodiment with reference to the accompanying drawings. In the drawing shows:

Figure 1 in the sectional view of a heat shield with a central through-hole, in which a screw and a cap according to the invention are positio ^¬ ned,

Figures in the sectional representation further Ausführungs2 to 4 forms of heat shields with through-hole,

Screw and cap,

Figures enlarged views of the cap shown in Figures 1 to 5 to 7 4 obliquely from below, from the side and from below,

8 shows in plan view the top of the cap body of the cap shown in the figures 5 to 7, 9 to be seen in Figures 5 and 6 ^¬ backup ring,

FIG. 10 shows a heat shield, as shown in FIGS. 3 and 4, with an alternatively designed cover cap and screw,

Figure 11 is detailed view of the heat shield according to the invention shown in Figure 10, the screw being ^¬ al ternatively designed

Figures 12-14 in FIGS. 10 and 11 show a cross section of an oblique top, bottom and top cap

obliquely above, Figure 15, the screw of Figure 14 with adjacent Siche ^¬ tion ring, and

Figure 16 is an enlarged sectional view of the recognizable in Figure 10 screw without swirl plate.

1 shows a sectional view of a heat shield 1 according to the invention. This comprises a main body 1 a with a flat upper section and with a heat insulating Layer 2 on the top of the main body la pointing upwards in the figure. In the base body la a central through-hole 3 is also provided. The heat shield is attached to a not ^{dargestell ¬} th in the figure 1 wall of a likewise not recognizable combustion chamber. For this purpose, the positioned in the central through-hole 3 screw 4 is screwed into a provided in the wall of the combustion chamber, also not shown threaded bore such that the screw 4 comes frictionally to a concern provided for this purpose in the central through-hole 3 stopper 5 and the Heat ^¬ shield 1 fixed in this way on the wall of the combustion chamber. The heat shield 1 has, as the sectional view can not be removed, a substantially rectangular shape. The combustion chamber is lined with a plurality of heat shields of the type shown.

In the central through-hole 3 of the heat shield 1 a cap 6 according to the invention is inserted. ^Covering cap 6 is shown enlarged in further views in FIGS. 5 to 7. As can be seen in particular the side view in Figure 6, the cap on a sleeve-shaped cap body 7, whose outer contour is adapted to the inner contour of the through-hole 3 in the upper region. The cap body is formed around the

Through hole 3 almost completely close.

Concretely, the cap body 7 has a plate-shaped, round upper wall 8 and an annular web 9 projecting downwardly therefrom. The diameter of the annular ridge 9 is smaller than the diameter of the upper wall 8. In this case, a region tapering from the outer edge of the upper wall 8 to the outside of the annular ridge 9 is provided, which serves as a stop 9a of the cap body 7 at the upper End of the penetration hole 3 is used. The penetration hole 3 has in this area a rounded edge 3b with an approximately quarter-circular cross-section on to which the cross-section also viertelkreisför ^¬-shaped stopper 9a is adjusted.

The top of the plate-shaped top wall 8 of the Cape penkörpers 7 is further provided with a heat insulation layer 10 verse ^¬ hen. This is made of a ceramic material and it is ge ^¬ suitable to keep temperatures of more than 1200 ° C to withstand.

In the top wall 8 of the cap body 7 are back about how well seen in Figure 8, which holds a view of the top ent ^¬, a total of four openings 11 are provided.

On the cap body 6, a receptacle 13 for the head 4a of the screw 4 is also provided. The receptacle 13 into which the screw head 4a fits with lateral play over about three four ^¬ tel its height is specifically defined by the underside of the upper wall 8 of the cap body and the In ^¬ inner side of the annular ridge 9. The overcap 6 also comprises fastening means, specifically a circlip 12, by means of which the cap body 7 is fixed by clamping to the head 4a of the screw 4. The Siche ^¬ approximately ring 12 which is designed to be open, consists of a bent wire of spring steel. As can be clearly seen in FIG. 9, the open circlip 12 concretely comprises an approximately semi-circular portion 12a and a V-shaped inwardly bent portion 12b at each of its two ends. When the retaining ring 12 is positioned on the cap body 7, the portion 12a engages around the cap body 7 on the outside in the region of the annular web 9. The V-shaped inwardly bent portions 12b at the two ends of the securing ^¬ ring further protrude through two opposing openings 14 in the wall of the annular web 9 in its interior. To attach the cap body 7 to the screw 4, the V-shaped inwardly projecting end portions 12b of the securing ring 12 are frictionally against the screw ^¬ head 4a. For a particularly secure fit of the cap body 7 on the screw head 4a is in its upper Rich further provided a circumferential groove 4b, in which engage the portions 12b of the retaining ring 12. In Figure 15, in which another embodiment of a screw is shown, the circumferential groove and the voltage applied to this V-shaped regions of the securing ring can be well ^{¬ he} knows.

As can be seen in Figure 1, the cap body 7 is further formed and fixed to the screw head 4a that between see the cap body 7 and the screw head 4a an annular channel 15 for guiding cooling air is defined when the cap 6 on the screw 4th is clamped by means of the Siche ^¬ approximately ring 12th Specifically, the cap body 7 is held by means of the retaining ring 12 on the screw head 4a, that the screw head 4a in the receptacle 13, which surrounds the screw head 4a with lateral play, since ^¬ Lich is centered. Between the inner wall of the receptacle 13 and the outer wall of the screw head 4a so a ring ^¬ shaped channel 15 is defined for guiding cooling air when the cap body 7 is clamped as shown in Figure 1 on the screw head 4a.

The means for guiding cooling air further comprise four channels 15a, which extend from the upper region of the annular channel 15 radially to the outside of the cap body 7 and four grooves which are provided on the outside of the cap body 7 in the region of the stop 9a. The grooves, which are not visible in the figure, extending in the region of the quarter-circle of the stopper 9a each of one of the radial channels 15a to the top of the cap body 7. The outwardly open grooves are closed by the inner wall of the through-hole 3, when the Cap body 7, as shown in the figure 1, positively in the

Through hole 3 is seated, so that channels for guiding cooling air are formed.

As an alternative to the embodiment shown here, it is also possible to use a cover cap which does not engage in grooves has its outside. The cooling air can also flow through an annular gap space, which is already formed, due to manufacturing tolerances, between the through-hole 3 and the cap body 7 positioned in it

In the illustrated embodiment, the grooves each open into one of four openings 11, which, as is clearly visible in Figure 8, are provided in the outer edge region of the upper wall 8. The openings 11 allow a particularly uniform leakage of cooling air into the combustion chamber. The openings 11 also allow a particularly comfortable lifting of the cap 6 of the penetration hole 3, since a suitable tool, such as a screw ^¬ puller can be inserted into this, to raise the cap comfortably.

For supplying cooling air into the interior of the

Durchgriffsbohrung 3 3 channels 17 are further provided in the bottom wall 3a of the through-hole, which extend vertically through the wall.

In the operation of the combustion chamber, not shown, prevail in this high temperatures in the range of 1200 ° C and more. The heat shield 1 is acted upon by cooling air via its openings, not shown in the drawing, which extend from its lower to its upper side through its wall.

It is further characterized by in the bottom wall 3a of the

Durchgriffsbohrung 3 provided channels 16 cooling air in the

Interior of the penetration hole 3 embedded. The cooling air flow is represented by corresponding arrows in the figures Darge ^¬ . The cooling air flows through the annular channel 15, which is defined between the screw head 4a and the inner wall of the cap body 7 in the region of the receptacle 13, on the head 4a of the screw 4 on the outside over. By the four Channels 15a, the cooling air is guided in the four grooves, which are provided on the outside in the region of the stopper 9a.

Through the grooves, the cooling air flows to the openings 11 in the upper wall 8 of the cap body 7 enters into the combustion chamber.

FIG. 2 shows a further heat shield 1 according to the invention, which is almost identical to that shown in FIG. The same components are provided with the same reference numerals. The only difference of this heat shield 1 to that shown in Figure 1 is that not in the bottom wall 3a of the through-hole 3 channels for the admission of cooling air into the interior of the

Durchgriffsbohrung 3 are provided, but that extend through the side wall 3b of the through-hole 3 channels 17 obliquely from below. The cooling air duct in the interior of the through-hole 3 corresponds to the cooling air duct of FIG. 1, except for the other inlet point. FIG. 3 shows a further heat shield 1 according to the invention, which is almost identical to the heat shields 1 shown in FIGS. Identical components are again provided with the same reference numerals. The only difference here is that in the heat shield 1 no channels for guiding cooling air in the wall of the through-hole 3 are provided. The supply of cooling air into the interior of the through-hole 3 takes place here by means provided in the screw 4 feed channel. The feed channel 18 extends centrally in the longitudinal direction through the screw 4. From this branch branches off at approximately middle height of the screw head 4a branch channels 19 radially outward ^¬ Shen, which open into the annular channel 15, between the outer wall of the screw head 4a and the inner wall the annular ridge 9 is defined. The cooling air flows in this annular channel 15 in the direction of the top of the cap body 7 and flows, as in the embodiments ge ^¬ according to Figures 1 and 2, through the radially branching channels 15a in the four grooves and through openings 11 in the combustion chamber, not shown.

FIG. 4 shows the heat shield 1 shown in FIG. In the embodiment shown in Figure 4 embodiment, the screw 4 is different from the Darge in Figure 3 ^¬ set characterized in that it comprises in the upper end of its head 4a has a conical recess 20, through which cooling air flowing through the central supply channel 18 in the

Screw 4 is inserted, can be performed evenly in the upper side ^¬ union end portion of the screw head 4a. From here, the cooling air, since the screw 4 is not fluid-tight against the underside of the upper wall 8 of the cap body 7, enters the annular channel 15 a. Magnified views obliquely from above and a sectional view of the screw 4 are included in the figures 14 to 16.

An alternative embodiment of a cap according to the invention can also be seen in Figures 10 to 13. This has a projecting from the underside of the upper wall 8 of the cap body 7 downwardly conical projection

21 on. The conical projection 21 can also be seen well in FIG. 13, which shows an enlarged view of the covering cap from FIGS. 10 and 11 obliquely from below. In Figure 13, the cap 6 is seen obliquely from above.

The conical projection 21 engages - when the cover cap is positioned in the through-hole 3 of the heat shield 19 - in the likewise conical recess 20 of the screw 4, which are identical in construction to that shown in Figure 4

Screw is. Between the conical recess 20 and the conical projection 21, a conical annular channel 22 is defined. The central supply duct 18 opens into the lower tip end portion of the conical annular channel 22, so that cooling air flowing through the supply passage 18 upward in the screw 4, can flow into the conical Ringka ^¬ nal. Through the conical annular channel

22, the cooling air in the upper outer area of the recording 14 out of which vertical channels 23 extend through the upper wall 8 of the cap body 7 to the combustion chamber.

In the central supply channel 18 is here also a

Swirl plate 24 is provided. By means of the swirl plate 24 is achieved that the cooling air is guided with a twist along the wall of the conical annular channel.

As an alternative or in addition to the swirl plate 24, the cooling air can also-as shown in FIG. 11 -continuously extend via channels 25, which extend horizontally through the screw wall in the lower end region of the screw 4 and open tangentially into the central feed channel 18 be routed to the feed channel.

Another difference of this embodiment of the cap according to the invention is that it has no four openings in the outer edge region in its upper wall 8, but two openings 26 which are provided somewhat centrally in the upper wall 8. The openings 26 are clearly visible in FIG. The openings 26 serve - as the openings 11 - the discharge of cooling air into the combustion chamber and a comfortable lifting the cap 6 of the penetration hole 3 by means of a suitable tool. As can be seen in Figures 10 and 11, the vertical channels 23 open out into the openings 26. The channels 23 connect the obe ^¬ ren end portion of the conical annular channel with the openings 26, cooling air may consist of the upper end portion of the conical annular channel 22 in the enter both vertical channels 23 and flow through the openings 26 into the combustion chamber.

Although the invention in detail by the preferred embodiment has been illustrated and described in detail, the invention is not limited ^¬ by the disclosed examples and other variations can be derived therefrom by the skilled artisan without departing from the scope of the invention.

Claims

claims

1. cap (6) for a penetration hole (3) in a heat shield (1) and in the penetration hole (3)

positionable fixing element (4) for fixing the heat shield ^¬ (1) to a wall, comprising

- A cap body (7) which is adapted to the

At least partially to close Durchgriffsbohrung (3) and on its upper side has a thermal barrier coating (10), and

- Fastening means (12) which are adapted to the cap body (7) releasably, in particular by clamping to the through-hole (3) and / or to fix the fixing element (4).

2. cap (6) according to claim 1, characterized in that the cap body (7) is sleeve-shaped, and in particular a plate-shaped round upper wall (8) and one of the upper wall (8) downwardly projecting annular web (9) having.

3. cap (6) according to claim 2, characterized in that the diameter of the annular web (9) is smaller than the diameter of the lid member (8), and in particular a from the outer edge of the lid member (8) to the outside ^¬ outside the annular web (9) tapering portion is provided which serves as a stop (9a) of the cap body (7) to an end portion of the through-hole (3).

4. Cover according to one of the preceding claims, characterized in that in the upper wall (8) of the cap ^¬ penkörpers (7) openings (11) are provided.

5. cap (6) according to any one of the preceding claims, characterized in that the fastening means comprise a Si ^¬ cherungsring (12) of the cap body (7) zumin- least partially engages around the outside and in particular Wenig ^¬ least has a portion which projects through at least one kor ^¬ respondierende lateral opening (14) in the cap body (7) inward.

6. Cover cap according to one of the preceding claims, characterized in ^{¬ ¬} characterized in that a downwardly open receptacle (13) is provided which is formed, at least one end portion of the fixing element, in particular the head (4a) of a screw (4), to receive, in particular in the on ^¬ assumption (13) a downwardly projecting projection (21) is provided.

7. cap (6) according to claim 5 and 6, characterized in that the securing ring (12) through the lateral

Openings (14) in the region of the receptacle (13) protrudes inwards.

8. cap (6) according to any one of the preceding claims, characterized in that guide means are provided for guiding cooling air, in particular comprise at least one extending through a wall of the cap body channel (15a, 23).

9. cap (6) according to claim 6 or 7 and 8, character- ized in that at least one channel (15a, 23) extends from the interior of the receptacle (13) to the outside of the cap ^¬ penkörpers (7), in particular at least one channel (15a, 23) at least substantially vertically through the upper wall (8) of the cap body (7) and / or at least one channel (15a, 23) at least substantially horizontally through a side wall of the cap body (7 ).

10. cap (6) according to any one of the preceding claims, characterized in that the cap body (7) made of metal and / or ceramic is made

11. cap (6) according to any one of the preceding claims, characterized in that the thermal barrier coating (10) ausge- is to include temperatures greater than 1000 ° C prior to hal ^¬ th, and in particular ceramic materials forms.

12 heat shield (1) with a thermal barrier coating (2) on its upper side and with a particular central Durchgriffs ^¬ bore (3), in the mounted state, a fixing element (4) for fixing the heat shield (1) is positioned on a wall, and with a cap (6) according to one of claims 1 to 11, which at the Durchgriffsbohrung (3)

and / or the fixing element (4) releasably, in particular by clamping is attached.

13. Heat shield (1) according to claim 12, characterized in that means are provided for cooling air in the

Engage through hole, wherein the means in particular channels (16, 17) which extend through a side wall (3b) and / or a bottom wall (3a) of the through-hole (3).

14. Heat shield (1) according to claim 12 or 13, characterized in that in the fixing element (4) at least one channel is provided for guiding cooling air, wherein in particular a extending in the longitudinal direction of the fixing element feed channel (18) is provided by the In particular at least one branch channel (19), in particular tangentially or radially, branches off.

15. Heat shield (1) according to any one of claims 12 to 14, ^¬ characterized in that the cap body (7) is designed such that between the cap body (7) and the fixing element (4) and / or between the cap body (7) and the through-hole (3) at least one channel (15) for guiding cooling air is defined when the cap body (7) on the through-hole (3) and / or on the fixing element (4) is fixed.

16. Heat shield (1) according to claim 15, characterized in that a downwardly open receptacle (13) on the cap (6) is provided, which is adapted to receive the upper Endbe ^¬ empire of the fixing element (4a) and that insbeson ^¬ dere between the inner wall of the receptacle (13) and the outer wall of the fixing (4) at least one channel (22) for guiding is defined by cooling air when the cap body (7) on the through-hole (3) and / or on the fixing element (4) is fixed.

17. Heat shield (1) according to claim 16, characterized in that in the upper end region of the fixing element (4) has a

Recess (20) is provided and in particular in the receiving ^¬ (13) a downwardly projecting projection (21) is provided, which is complementary to the recess (20), such that between the projection (21) and the Vertie - Fung (20) at least one in particular annular channel (22) for guiding cooling air is defined when the cap body (7) on the through-hole (3) and / or on the fixing element (4) is fixed.

18 heat shield (1) according to claim 17, characterized in that the projection (21) and the recess (20) are conical, so that a conical annular channel (22) is defined when the cap body (7) at the through-hole ( 3) and / or on the fixing element (4) is attached.

19. Heat shield (1) according to any one of claims 12 to 18, ^¬ characterized in that on the penetration hole (3) and / or on the cap body (7) fastening means are provided, via which the cap (7) releasably, insbesonde- re clamping, on the through-hole (3) and / or on the fixing element (4) can be fixed, wherein the fastening ^¬ supply means in particular comprise a locking ring (12).

20. Heat shield (1) according to claim 19, characterized in that in the upper end region of the fixing means (4) has a groove (4b) is provided, in which the fastening means, in particular the securing ring (12), can engage.

21. Heat shield (1) according to claim 20, characterized in that the cap body (7) is sleeve-shaped, wherein the retaining ring (12) surrounds the cap body (7) at least partially on the outside and by lateral openings (14) in the cap body (7 ) projects inwards, in particular in the region of a receptacle (13), see provided on the covering cap (6) ^¬ and adapted to receive at least the upper end portion of the fixing element (4), such that the Siche ^¬ approximately ring (12) for Fastening of the cap (6) frictionally in abutment with the fixing element (4) can be brought, in particular in the region of the groove (4b).

22. Heat shield (1) according to one of claims 12 to 21, ^¬ characterized in that the outer contour of the cap body (7) is adapted to the inner contour of the through-hole (3) in its upper-side end region.

23. Heat shield (1) according to any one of claims 12 to 22, ^¬ characterized in that the cap (6) is designed such that it at least substantially the top of the heat shield (1) in the region of the penetration hole (3) flush closes.