Patent Publication Number: US-7909289-B2

Title: Closure system for a support structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of parent U.S. patent application Ser. No. 10/943,251 filed on Sep. 17, 2004, now U.S. Pat. No. 7,503,523 the disclosure of which is expressly incorporated by reference herein in its entirety. The present application also claims priority under 35 U.S.C. §119 of German Patent Application No. 103 43 627.8, filed on Sep. 20, 2003, the disclosure of which is expressly incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a closure device for a support structure that is, e.g., an area of the outer contour of an aircraft that can be opened and closed for the purpose of access. 
     2. Discussion of Background Information 
     In aircraft, such closure devices are provided, in particular, as hatches for maintenance and inspection purposes, as a radome, as a passenger or cargo compartment door, or for a similar purpose. If such a closure device is provided for maintenance or inspection purposes, it is often necessary for it to be possible for these parts of the outer contour to be opened and closed more or less quickly, which is the case anyway with a passenger or cargo compartment door. It is thereby essential, in particular, if the aircraft is a high-speed aircraft, that the aerodynamic outer contour is only slightly impaired thereby and that the mechanical connection to the rest of the structure of the aircraft reliably withstands the operating loads occurring. 
     Very different solutions have hitherto been realized for such closure devices, whereby most of the mechanisms comprise hinge elements and locking elements of different types. Depending on the required opening angle of the closure device, and the necessity of integrating it into the structure of the aircraft as a supporting element, very solid hinges sometimes result. The closure devices are often embodied by locking elements in the form of hooks or shear pins. 
     If the aircraft is a combat aircraft, expensive measures are often taken to damp the radar reflection values in the area of the closure devices, i.e., at the hinge, the lock and at gaps or steps at the transition between the closure device and the rest of the outer skin of the aircraft. Moreover, these locations are more or less responsible for aerodynamic resistance and thus for the fuel consumption of the aircraft. 
     SUMMARY OF THE INVENTION 
     The invention aims to provide an improved closure device of the type mentioned. 
     This aim is attained by providing a closure device having one or more of the features described below. Advantageous further developments of the closure device according to the invention are also described herein. 
     According to the invention, a closure device is created for an area of the outer contour of an aircraft which can be opened and closed for the purpose of obtaining access. The closure device has a hinge through which the closure device is connected to the structure of the aircraft and about which the closure device can be pivoted between an opened position and a closed position. It also has a locking device with which the closure device can be locked against the structure of the aircraft in the closed position. According to the invention, the hinge is arranged inside the outer contour of the aircraft and has a virtual axis of rotation located outside the outer contour of the aircraft. It is about this axis that the closure device is pivoted during opening and closing. The locking device is embodied such that in the closed state it connects the closure device to the structure of the aircraft in a form-locking manner. In this way, the locking device essentially completely relieves the hinge. 
     One advantage of the closure device according to the invention is that it guarantees improved aerodynamic properties of the aircraft. This is because it manages to do so without a hinge lying on the outside. Another advantage is that the static properties of the connection are improved. Furthermore, gaps and steps are reduced or avoided in the aircraft structure, which is conducive to a reduction of the aerodynamic resistance and, if desired, of the radar echo. A further important advantage is that, in the closed state of the closure device, the hinges do not bear the operating loads and can thus be built in a relatively light manner. A further advantage is the small space requirement for the invention and the great compactness of the closure device. Another very important advantage is that there is a very low risk of blocking the closure device, so that it is fail-safe and works effectively. 
     According to the invention, a closure device for opening and closing a structural part arranged on a support structure, with at least one hinged joint device for the flexible connection of the body part to the structural part and with a locking device with which the closure device can be locked in the closed position, is provided. The at least one hinged joint device is arranged inside the vehicle structure and has an axis of rotation of the structural part about which the same can be pivoted during opening and closing. The axis of rotation is located on the side to which the structural part can be pivoted for opening. The locking device is embodied such that in the closed state it connects the structural part to the support structure in a form-locking manner while relieving the hinged joint device. 
     The locking device can comprise at least one first flange that can be arranged on the structural part and at least one second flange that can be arranged on the support structure and that interacts with the first flange. A blocking device interacts with first and second flanges such that in the closed position it provides a form-closed locking between the first flange and the second flange. The locking device also has a tightening mechanism with which the blocking device can be tightened or released on or relative to the flanges. 
     The hinged joint device can include two legs flexibly coupled to one another, wherein the first leg is attached to the structural part and the second leg is attached to the support structure. The joint axis that connects the two legs to one another can run in the direction of the axis of rotation of the closure device. Alternatively, the hinged joint device can include two legs which are flexibly coupled to one another with a first axis, a second axis and a center axis, wherein these axes intersect at a point located on the axis of rotation of the closure device. 
     The first flange and the second flange can respectively form a curve running in a completely closed manner. The first flange and/or the second flange can also act to limit the outer circumference of a passage opening that can be closed by the closure device. Furthermore, the first and second flange can be circular, oval or composed of several parts of circular and/or oval flanges. 
     The first and second flange can respectively lie in one plane. The parts of circular and/or oval flanges of which the first and second flange are respectively composed can lie in different planes that intersect where the parts of the flange touch one another. 
     The blocking device can be formed by a chain or belt arrangement for locking the first and second flange. In the closed state of the closure device, the chain or belt arrangement can be arranged to run radially outside and around the circumference of the first and second flange. On sides facing one another, the first and second flange respectively feature stop surfaces that rest against one another when the closure device is closed. The flanges also feature first locking surfaces on sides facing away from one another. The chain or belt arrangement includes a number of clamp elements that feature respective second locking surfaces interacting in a form-locking manner with the first locking surfaces provided on the first and second flanges. The chain or belt arrangement has a tightening mechanism with which the chain or belt arrangement is adjustable in its length for releasing or tightening the same between an extended and/or expanded state in which the first locking surfaces of the first and second flanges and the second locking surfaces of the clamp elements are free of one another so as to release the closure device, and a contracted and/or retracted state in which the first locking surfaces of the first and second flanges and the second locking surfaces of the clamp elements are fixed against one another to lock the closure device. 
     Alternatively, the blocking or locking device can be composed of a chain arrangement which enables the locking of the first and second flange, wherein in the closed state of the closure device, the arrangement is arranged to run around the circumference of the first and second flange. The first and second flanges respectively feature stop surfaces on sides facing one another that rest against one another when the closure device is closed and first locking surfaces on sides facing away from one another. The flexible chain arrangement includes a number of clamp elements which feature respective second locking surfaces interacting in a form-locking manner with the first locking surfaces provided on the first and second flanges. The chain arrangement features a tightening mechanism with which the chain arrangement is adjustable in its radial length between a first position in which the first locking surfaces of the first and second flanges and the second locking surfaces of the clamp elements are free of one another to release the closure device, and a second position in which the first locking surfaces of the first and second flanges and the second locking surfaces of the clamp elements are fixed against one another to lock the closure device. 
     The chain arrangement can be arranged to run radially outside around the circumference of the first and second flanges, whereby in the first position, the closure device is released and the clamp elements of the chain arrangement adopt a position lying radially further outwards, and whereby in the second position, the closure device is locked and the clamp elements adopt a position lying radially further inwards. Alternatively, the chain arrangement can be arranged to run radially inside the first and second flanges, whereby, in the first position, the closure device is released and the clamp elements of the chain arrangement adopt a position lying radially further inwards and in the second position the closure device is locked and the clamp elements adopt a position lying radially further outwards. 
     The first locking surfaces can form an outer conical cross-sectional shape which tapers outwards, and the second locking surfaces can form an inner conical cross-sectional shape which taper outwards and which matches the former during locking. 
     The chain or belt arrangement can be arranged in a fixed manner with respect to one of the first or second flanges and on the side facing the other flange. The clamp elements can feature a sliding block surface tilted outwards by way of which the clamp elements can be displaced radially outwards during closing of the closure device. This can occur through the other flange in order to engage the first locking surface of the other flange behind the assigned second locking surface of the clamp elements. 
     The tightening mechanism can include a thread tightener which acts between respective opposite ends of the chain or belt arrangement and a helical gear for operating the same. The helical gear contains a gear wheel coupled to the thread tightener and a worm wheel coupled to a drive element. The drive element can thereby be a hand twist grip. The hand twist grip can be coupled to the worm wheel via a ball lock that can be unlocked by way of a separate operating element. This can occur, in particular, by way of a push button. Furthermore, the hand twist grip can be displaceable in the direction of its axis of rotation between a lowered position, in which it is secured against rotation, and a raised or not lowered position in which it is released for rotation. A spring can be provided through which the hand twist grip is displaced during unlocking by the ball lock from the lowered position into the raised or not lowered position. 
     The tightening mechanism can also contain a pressure hose arranged between the clamp elements and a contact surface lying radially displaced thereto. The hose can be acted on by a hydraulic or pneumatic drive medium. A pressure medium pump is connected to the pressure hose for feeding the drive medium to the pressure hose. In this way, acting on the pressure hose with the drive medium creates a cross-sectional enlargement of the pressure hose and causes a radial displacement of the clamp elements from the first position to the second position in order to lock the closure device. Draining the drive medium from the pressure hose produces a cross-sectional reduction of the same and causes a radial displacement of the clamp elements from the second position to the first position in order to release and/or unlock the closure device. The clamp elements can be spring-preloaded to provide radial displacement from the second position to the first position, so that on releasing pressure of the drive medium from the pressure hose, a displacement of the clamp elements takes place automatically through the spring action from the second position to the first position to release the closure device. Alternatively, the clamp elements can be radially displaceable by draining the drive medium from the pressure hose, thereby producing a cross-sectional reduction of the same, to release the closure device from the second position to the first position. 
     The chain or belt arrangement can be arranged on the structure of the aircraft. The chain or belt arrangement can also be arranged on the closure device. 
     The closure device according to the invention can be a radome, a maintenance or inspection hatch, or a landing-gear door. The closure device can also be a two-leave door using a first leaf and a second leaf, whereby a center closure is used and is activated by the chain arrangement. Alternatively, other activation mechanisms can be provided between the leaves. The closure device can furthermore be a passenger door. 
     The invention also provides for a system for opening and closing a structural part arranged on a support structure, wherein the system comprises at least one hinged joint device for flexibly connecting the structural part to the support structure. The at least one hinged joint device is arranged inside the support structure and has an axis of rotation about which the structural part can be pivoted relative to the support structure during opening and closing. A locking arrangement is structured and arranged to connect the structural part to the support structure in a form-locking manner when the structural part is in a closed position. In the closed position, the locking arrangement is arranged to relieve the at least one hinged joint device. 
     In the closed position, the locking arrangement may be arranged to lock the structural part to the support structure such that the at least one hinged joint device is substantially free of forces normally acting on the at least one hinged joint device when the structural part is in a opened position. In the closed position, the locking arrangement may be arranged to lock the structural part to the support structure such that the at least one hinged joint device does not substantially participate in securing the structural part to the support structure. 
     The locking arrangement may comprise at least one first flange arranged on the structural part and at least one second flange interacting with the first flange and arranged on the support structure. The locking arrangement may further comprise a locking device which interacts with the first and second flanges, wherein, in the closed position, the locking device locks the first and second flanges to each other. The locking arrangement may comprise a tightening mechanism. The tightening mechanism may be structured and arranged to lock and unlock the locking device relative to the first and second flanges. The tightening mechanism may be structured and arranged to radially expand and contract the locking device relative to at least one of the first and second flanges. 
     The at least one hinged joint device may comprise first and second legs flexibly coupled to one another, the first leg being attached to the structural part and the second leg being attached to the support structure. A joint axis that connects the first and second legs to one another may run at least one of along a direction of the axis of rotation and parallel to the axis of rotation. 
     The at least one hinged joint device may comprise two legs flexibly coupled to one another. The at least one hinged joint device may comprise a first axis, a second axis, and a third axis, wherein the first, second and third axes intersect at a point located on the axis of rotation. The locking arrangement may comprise a first flange arranged on the structural part and a second flange arranged on the support structure. At least one of the first and second flanges may comprise a completely closed curved flange. At least one of the first and second flanges may comprise a continuously curved flange. At least one of the first and second flanges may define an outer circumference or perimeter of a passage opening. At least one of the first and second flanges may be generally circular. Each of the first and second flanges may be generally circular. At least one of the first and second flanges may be generally oval. Each of the first and second flanges may be generally oval. At least one of the first and second flanges may comprise at least one of a plurality of partially circular sections and a plurality of partially oval sections. At least in the closed position, the first and second flanges respectively lie on a common plane. 
     The locking arrangement may comprise a first flange arranged on the structural part and a second flange arranged on the support structure, whereby each of the first and second flanges comprise at least two curved sections which lie on different planes. The locking arrangement may comprise a first flange arranged on the structural part and a second flange arranged on the support structure, whereby each of the first and second flanges comprise at least two adjacent curved sections which are oriented on different planes that interest one another. 
     The locking arrangement may comprise a chain or belt arrangement structured and arranged to lock a first flange of the structural part to a second flange of the support structure. The chain or belt arrangement may be arranged radially outside and around a circumference of the first and second flanges. The first and second flanges may respectively comprise opposite facing stop surfaces which rest against one another in the closed position. The first and second flanges may respectively comprise first locking surfaces which face away from each other. The chain or belt arrangement may comprise a plurality of clamp elements. Each of the plurality of clamping elements may comprise second locking surfaces which interact in a form-locking manner with the first locking surfaces of the first and second flanges. Each of the plurality of clamping elements may comprise second locking surfaces which engage with the first locking surfaces of the first and second flanges. Each of the plurality of clamping elements may comprise second locking surfaces which sealingly engage with the first locking surfaces of the first and second flanges. 
     The chain or belt arrangement may comprise a tightening mechanism adapted to adjustable an overall length of the chain or belt arrangement. The tightening mechanism may be structured and arranged to release or tighten the chain or belt arrangement, whereby the chain or belt arrangement is movable between an expanded state in which the first locking surfaces and the second locking surfaces are not forced against each other so as to allow the first and second flanges to separate from one another, and a contracted state in which the first locking surfaces and the second locking surfaces are forced against one another to lock the structural part in the closed position. The tightening mechanism may be structured and arranged to release or tighten the chain or belt arrangement, whereby the chain or belt arrangement is movable between an expanded unlocked state in which the first locking surfaces and the second locking surfaces are not forced against each other and a contracted locked state in which the first locking surfaces and the second locking surfaces are forced against one another. The tightening mechanism may be structured and arranged to release and tighten the chain or belt arrangement, whereby the chain or belt arrangement is movable between an expanded unlocked state in which the second locking surfaces are not forced against the first locking surfaces and a contracted locked state in which the second locking surfaces are forced against the first locking surfaces. 
     The chain or belt arrangement may be arranged to surround an outer surface the first and second flanges in the closed position. The chain or belt arrangement may be arranged to surround an outer circumferential surface the first and second flanges in the closed position. The chain or belt arrangement may comprise a flexible chain arrangement. The flexible chain arrangement may comprise a plurality of clamp elements which include second locking surfaces which engage in a form-locking manner with first locking surfaces arranged on the first and second flanges. 
     The system may further comprise a tightening mechanism structured and arranged to release and tighten the flexible chain arrangement, whereby the chain or belt arrangement is movable between a radially expanded position in which the second locking surfaces are not forced against the first locking surfaces and a radially contracted position in which the second locking surfaces are forced against the first locking surfaces. The tightening mechanism may be adapted to adjustable an overall circumferential length of the flexible chain arrangement. The tightening mechanism may be adapted to adjust an overall radial area of the flexible chain arrangement. The chain or belt arrangement may be arranged to at least partially surround the first and second flanges. 
     The chain or belt arrangement may be movable between a first position wherein clamp elements of the chain or belt arrangement are arranged in a radially outward position and a second position wherein the clamp elements are arranged in a radially inward position. The chain or belt arrangement may be movable between a first position wherein clamp elements do not engage with each of the first and second flanges and a second position wherein the clamp elements engage with each of the first and second flanges, whereby the second position is radially inwards relative to the first position. The chain or belt arrangement may be movable between a first position wherein clamp elements engage with each of the first and second flanges and a second position wherein the clamp elements do not engage with each of the first and second flanges, whereby the second position is radially inwards relative to the first position. The first and second flanges may each comprise a first conical locking surface, wherein the chain or belt arrangement comprises second conical locking surfaces structured and arranged to engage the first conical locking surfaces when the structural part is in the closed position. 
     The first and second flanges may each comprise a first tapered locking surface, wherein the chain or belt arrangement comprises second tapered locking surfaces structured and arranged to engage the first tapered locking surfaces when the structural part is in the closed position. The first and second flanges may each comprise a first tapered locking surface and the chain or belt arrangement may comprise second tapered locking surfaces structured and arranged to engage the first tapered locking surfaces when the structural part is in the closed position, whereby the second locking surfaces generally correspond to the first locking surfaces. The chain or belt arrangement may remain arranged on the first flange when the structural part is in a opened position. The chain or belt arrangement may remain arranged on the second flange when the structural part is in a opened position. The chain or belt arrangement may comprise a sliding block surface which tapers outwards and which faces towards the first flange, whereby the chain or belt arrangement expands outwardly when sliding block surface engages with the first flange. The chain or belt arrangement may comprise clamp elements having sliding block surfaces which taper outwards and which face towards the first flange, whereby the chain or belt arrangement expands outwardly when sliding block surfaces engage with the first flange. 
     The chain or belt arrangement may comprise a sliding block surface which tapers outwards and which faces towards the second flange, whereby the chain or belt arrangement expands outwardly when sliding block surface engages with the second flange. The chain or belt arrangement may comprise clamp elements having sliding block surfaces which taper outwards and which face towards the second flange, whereby the chain or belt arrangement expands outwardly when sliding block surfaces engage with the second flange. The system may further comprise a tightening mechanism for radially expanding and contracting the chain or belt arrangement. The tightening mechanism may comprise a thread tightener acting between respective opposite ends of the chain or belt arrangement and a helical gear for rotating the thread tightener. The helical gear may comprise a gear wheel and a worm wheel. The gear wheel may be coupled to the thread tightener and the worm wheel is coupled to a drive element. The drive element may be a hand twist grip. The hand twist grip may be coupled to the worm wheel via a ball lock adapted to be unlocked via one of an operating element and a push button. The hand twist grip may be movable in a direction of a axis of rotation of the drive element between a lowered position, in which the hand twist grip is secured against rotation, and another position in which the hand twist grip is capable of rotating. The tightening mechanism may further comprise a spring arranged to move the hand twist grip, whereby the spring can move, during unlocking, the ball lock from the lowered position to the other position. 
     The tightening mechanism may comprise an inflatable hose arranged between clamp elements and a contact surface which is spaced from the clamping elements. The inflatable hose may be adapted to inflate via one of a hydraulic medium and a pneumatic medium. The system may further comprise a pressure pump coupled to the inflatable hose, wherein the pressure pump is structured and arranged to inflate the pressure hose. Inflation of the pressure hose may cause a radial expansion of the chain or belt arrangement. Inflation of the pressure hose may cause a radial contraction of the chain or belt arrangement. 
     The system may further comprise a mechanism for biasing chain or belt arrangement from an expanded state to a contracted state. The system may further comprise a mechanism for biasing chain or belt arrangement from a contracted state to an expanded state. The system may further comprise a mechanism for automatically biasing chain or belt arrangement from an expanded state to a contracted state. The system may further comprise a mechanism for automatically biasing chain or belt arrangement from a contracted state to an expanded state. The chain or belt arrangement may be adapted to automatically move a contracted state to an expanded state. The chain or belt arrangement may be adapted to automatically move from an expanded state to a contracted state. The locking arrangement may further comprise an inflatable hose, wherein clamp elements of the chain or belt arrangement are radially displaceable by removing a fluid from within the inflatable hose. 
     The locking arrangement may further comprise an inflatable hose, wherein clamp elements of the chain or belt arrangement are radially displaceable by feeding a fluid into the inflatable hose. The vehicle may comprise an aircraft. The structural part may comprise one of a radome, a maintenance hatch, an inspection hatch, a landing-gear door system, and a passenger door. 
     The invention also provides for a system for locking a movably mounted structural part to a support structure of a vehicle, wherein the system comprises at least one hinge pivotally connecting the structural part to the support structure and a locking arrangement structured and arranged to releasably connect at least one flange of the structural part to at least one flange of the support structure. In the closed position, the locking arrangement is arranged to lock the structural part to the support structure such that the at least one hinge is substantially free of forces normally acting on the at least one hinge when the structural part is in a opened position. 
     The invention also provides for a system for locking a movably mounted structural part to a support structure of a vehicle, wherein the system comprises at least one hinge pivotally connecting the structural part to the support structure and a locking arrangement structured and arranged to releasably connect at least one curved flange of the structural part to at least one curved flange of the support structure. The locking arrangement comprises a chain or belt arrangement and a mechanism for moving the chain or belt arrangement between an expanded state and a contracted state. 
     Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein: 
         FIG. 1  shows an isometric view of a combat aircraft in which exemplary embodiments of the closure device according to the invention can be used; 
         FIG. 2  shows an isometric view of a radome of a combat aircraft as shown in  FIG. 1 . The radome is in the opened state and uses a first exemplary embodiment of the invention; 
         FIG. 3  shows a detailed view of a hinge system of the radome shown in  FIG. 2 ; 
         FIG. 4  shows a section view of the radome shown in  FIG. 2  in the symmetry plane in the closed state; 
         FIGS. 5   a  and  5   b  show detailed views of a locking device that serves to lock the closure device of an exemplary embodiment of the invention; 
         FIG. 6  shows a plan view of the front structural spar of the aircraft shown in  FIG. 1  to which the radome (not shown in the Fig.) is attached; 
         FIG. 7  shows a corresponding view of the radome with a locking device according to an exemplary embodiment of the invention; 
         FIG. 8  shows a detailed view to explain the operational principle of the locking device; 
         FIGS. 9   a - 9   c  show individual phases of a closing sequence of the locking device; 
         FIGS. 10   a  and  10   b  show diagrammatic views which illustrate the operational principle of the locking device; 
         FIGS. 11   a  and  11   b  show detail views of a tightening mechanism used for opening and closing the locking device; 
         FIGS. 12   a - 12   c  show cross-sectional views of a helical gear for operating the locking device; 
         FIG. 13  shows an isometric view of a closure device in the form of an access flap according to a second exemplary embodiment of the invention in the opened state; 
         FIG. 14  shows a plan view of the access flap shown in  FIG. 13  in the closed state from the inside of the aircraft; 
         FIG. 15  shows a plan view of the access flap shown in  FIG. 13  in the opened state from the outside of the aircraft; 
         FIG. 16  shows an isometric view of a closure device in the form of an access flap according to a third exemplary embodiment of the invention in the closed state, seen from the inside of an aircraft; 
         FIG. 17  shows a plan view of the access flap shown in  FIG. 16  from the inside of the aircraft; 
         FIG. 18  shows a plan view of the access flap shown in  FIG. 16  in the opened state from the outside of the aircraft; 
         FIGS. 19   a - 19   c  show cross-sectional views of a helical gear for operating the locking device of the access flap shown in  FIG. 16  according to an exemplary embodiment of the invention; 
         FIG. 20  shows an isometric view of a passenger aircraft in which closure devices according to exemplary embodiments of the invention can be used; 
         FIG. 21  shows an isometric view of a closure device in the form of a passenger door in the opened state seen from outside the aircraft; 
         FIGS. 22   a - 22   c  show a cross-sectional view and plan views of the passenger door shown in  FIG. 21  in closed and in opened positions; 
         FIG. 23  shows an isometric view of the passenger door shown in  FIG. 21  with a hinge mechanism according to an exemplary embodiment of the invention; 
         FIG. 24  shows an isometric view of a closure device in the form of a landing-gear door comprising two leaves, in the closed position, seen from inside the aircraft according to another exemplary embodiment of the invention; 
         FIG. 25  shows a cross-sectional view through the two-leaved landing-gear door of  FIG. 24  along the line A-A in the closed state (indicated by a solid line) and in the opened state (indicated by a dot-dash line); 
         FIGS. 26   a - 26   c  show individual phases of a closing sequence of a locking device according to a further exemplary embodiment, and as is explained on the basis of the landing-gear door shown in  FIGS. 24 and 25 ; 
         FIGS. 27   a  and  27   b  show isometric views of a closure device in the form of a passenger door according to a further exemplary embodiment of the invention in the closed state, as seen from inside the aircraft or in the opened state seen from outside the aircraft; and 
         FIGS. 28   a  and  28   b  show a detailed view in sectional form along the line B-B in  FIG. 27   a  according to a further exemplary embodiment of the invention which is provided for locking the passenger door shown in  FIG. 27 . 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. 
     According to the invention, a closure element, which in general can be a structural part, e.g., a cover or a door, is arranged on a support structure in a moveable manner. The closure device, in general, is provided to pivot the closure element arranged, e.g., on the outer contour of a support structure (e.g., a vehicle), in order to be able to open and close and lock an access opening of the support structure. In particular, the support structure can be a vehicle structure into the interior of the same one can obtain access. 
     The closure device according to the invention can be used, e.g., to open and close a radome arranged on an aircraft. In this example, the aircraft is the aforementioned structural part or support structure. Thus,  FIG. 1  shows in isometric view a combat aircraft  1  on which the closure device according to the invention can be used according to one or more of the exemplary embodiments of the invention. As can be seen in  FIGS. 1-3 , a radome  10  is arranged to cover a front radar scanner  14  of the aircraft  1 . One or more closure elements  20  in the form of access flaps or hatches are provided for inspection or maintenance purposes on the aircraft. As will be explained in detail below, landing gear doors  30  can also utilize the closure device of the invention. 
       FIG. 2  shows in isometric view an embodiment of the closure device used with a radome  10 . In this embodiment, the radome  10  constitutes the closure element and the aircraft  1  constitutes the support structure. In the position shown in  FIG. 2 , the radome  10  is in the opened state. The closure element or the structural part in the form of the radome  10  is pivoted opened and closed by way of one or more hinged joint devices  90  (see also  FIG. 3 ). In the embodiment shown in  FIG. 2 , two hinged joints  11 ,  12  are arranged on a support structure  19  of the aircraft  1 . The radome  10  can be opened and closed in order to make accessible certain internal mechanisms. For example, the radome  10  can be opened to provide access for maintenance a radar scanner  14  covered by the radome  10 . When closed, the radome  10  forms part of the outer contour of the aircraft  1 . The scanner  14  is accommodated in a passage opening  18 . A first flange  15  is provided on the radome  10 . A second flange  16  is arranged on the support structure  19  of the aircraft  1 . These flanges  15 ,  16  form, together with a chain or belt arrangement  17 , a locking device with which the radome  10  can be fixed and securely held on the structure  19  of the aircraft  1 . The locking device is such that it can lock the radome  10  to the structure  19  while essentially completely relieving the hinged joints  11 ,  12 . 
     In general, therefore, a first flange  15  is arranged on the closing element or structural part  10 , and a second flange  16  is arranged on the support or vehicle structure. These flanges  15  and  16  rest against one another and thereby interact in a form-locking manner in the closed position of the closure device. In this way, the structural part  10  can close the access opening  18  of the vehicle  1 . From the point of view of the side to which the structural part can be pivoted into an open position, the hinged joint device(s) are arranged inside the vehicle structure and feature an axis of rotation X which is located outside the vehicle structure for moving the structural part  10 . The locking device is thereby embodied such that in the closed state it locks the structural part  10  with the support structure  19  in a form-locking manner while relieving the hinged joint arrangements. 
     According to the invention, a hinged joint arrangement  90  includes at least one hinged joint. In the embodiment shown in  FIG. 3 , the hinged joint arrangement  90  is formed by two hinged joints in the form of two so-called pyramid gears  90   a  and  90   b . Each gear  90   a  and  90   b  is composed of a first leg  91  and a second leg  92  and these legs are connected to one another at their first end by a common axis or swivel axis  95 . The first leg  91  is also connected at its second end via a first axis or fixed axis  93  to the radome  10 . The second leg  92  is connected at its second end via a second axis or fixed axis  94  to the structure  19  of the aircraft  1 . The first and the second axis  93 ,  94  are respectively oriented at an angle to the common axis  95  which can typically lie in the range of between approximately 40° and approximately 80°. As can be seen at the lower hinge in  FIG. 3 , when the radome  10  is opened, a pivoting about a virtual axis of rotation labeled X occurs. This axis of rotation lies outside the outer contour of the aircraft  1 . This also means that the axis of rotation X of the structural part  10 , about which the same can be pivoted during opening and closing, is located on the side to which the structural part  10  can be pivoted to open. 
     The term pyramid gears  90   a ,  90   b  describes the property of the hinged joint devices  90   a ,  90   b  according to which the three axes, i.e., the first axis  93 , the second axis  94  and the center axis  95 , intersect at a common point. This point is located on the axis of rotation of the closure device in order to avoid a mechanical incompatibility (jamming) of the hinged joint devices. 
     In general, the at least one hinged joint device  90  can also be embodied as a parallelogram hinged joint device in which the hinged joint device is composed of two legs which are flexibly coupled to one another (see e.g.,  FIGS. 23 and 27 ). The first leg can be attached to the structural part and the second leg can be attached to the support structure, whereby the joint axes of the two legs run parallel and/or in the direction of the axis of rotation X of the closure device. 
     In any case, the axis about which the structural part can be pivoted is arranged outside the vehicle structure from the point of view of the side to which the structural part can be pivoted into an open position. 
     With the hinged joint device having the form of a pyramid gear  90 , the pivoting about the axis of rotation X is caused, on the one hand, by opening the first and second legs  91 ,  92  which rotate about their common swivel axis  95 , and on the other hand, by rotating the legs  91 ,  92  about the fixed axes  93 ,  94 . With the pivoting motion about the virtual axis of rotation X, the structural part or the radome  10  is fixed with respect to the supporting structure  19  virtually in the same manner as would be the case with a pivoting about a hinge with an actual axis of rotation in place of the virtual axis of rotation X. 
     In the closed position shown in  FIG. 4 , it can be seen that the radome  10  is attached to the structure  19  of the aircraft  1  by way of a locking device. Details A and B are shown in  FIGS. 5   a  and  5   b . The locking device includes a first flange  15  that is arranged on the structural part or radome  10  and a second flange  16  that is provided and/or arranged on the structure  19 . The flanges  15 ,  16  are embodied such that they interact in a form-locking manner. Furthermore, the locking device features a blocking or locking arrangement  17  that can be embodied, in particular, as a chain or belt arrangement (see  FIGS. 5   a ,  5   b ). In the closed state, the locking arrangement  17  provides a form-closed locking between the first flange  15  and the second flange  16 . The blocking device or the chain or belt arrangement also includes a tightening mechanism  70  with which the chain or belt arrangement can be tightened onto or loosened from the flanges  15 ,  16 . 
       FIGS. 6 and 7  show in plan view the second flange  16  provided on the structure  19  of the aircraft  1 . The first flange  15  provided on the radome  10  together with the blocking device or chain or belt arrangement  17  and the tightening mechanism  70  is also shown. The chain or belt arrangement utilizes a sliding cam SC. The first flange  15  and the second flange  16  respectively form a curve running in a completely closed manner. In this exemplary embodiment, the completely closed curve is in the form of a complete circle. As is also evident in  FIG. 7 , the first flange  15  arranged on the radome  10  limits the circumference of the passage opening  18  that is provided for the radar scanner  14  to pass through. 
     The operational principle of the locking device formed by the first flange  15 , the second flange  16  and the blocking device in the form of a chain or belt arrangement  17  will now be explained in more detail with reference to  FIGS. 8 through 10 . In the closed position of the closure device, and thus in the closed position of the radome  10 , the first flange  15  and the second flange  16  rest against one another, see  FIGS. 8 and 9   c . As a result, the stop surfaces  56  and  57 , which are arranged to face one another (see  FIG. 9   a ) contact one another. A plurality of clamp elements  61  are provided on a flexible chain or belt arrangement. These clamp elements  61  are connected to one another by the chain or belt arrangement  60  (see  FIGS. 9   a  and  b  and  FIG. 10   a  and  10   b ). The clamp elements  61  feature respective second locking surfaces  64 ,  65  which interact in a form-locking manner with first locking surfaces  52 ,  53  provided on the sides of the flanges  15 ,  16  facing away from one another (see  FIGS. 9   a - 9   c ). 
     The tightening mechanism  70 , which in  FIG. 10  is indicated only diagrammatically by arrows, is used to changed an overall length of the chain or belt arrangement  17  between an extended and/or expanded state, in which the first locking surfaces  52 ,  53  of the first flange  15  or of the second flange  16  and the second locking surfaces  64 ,  65  of the clamp elements  61  are free of one another so as to release the closure device  10 , and a contracted state in which the first locking surfaces  52 ,  53  of the first and second flanges  15 ,  16  and the second locking surfaces  64 ,  65  of the clamp elements  61  are fixed and/or engage against one another to provide for locking engagement. 
     As  FIGS. 8 and 9  show, the first locking surfaces  52 ,  53  provided on the flanges  15 ,  16  form an outer conical cross-sectional shape which tapers outwards in the radial direction. The second locking surfaces  64 ,  65  provided on the clamp elements  61  form an inner conical cross-sectional shape which tapers outwards in the radial direction and which generally matches the cross-sectional shape of the first locking surfaces  52 ,  53 . As a result, when the locking arrangement  17  and flanges  15  and  16  are in the position shown in  FIGS. 9   c  and  10   a , the closure device can be said to be locked a form-locking manner. 
     The chain or belt arrangement  17 , which includes the chain or belt element  60  and the clamp elements  61  arranged thereon, is also arranged in a fixed manner with regard to one of flanges. In the exemplary embodiment shown, this flange is the first flange  15 . As a result, the clamp elements  61  have, on the side facing the second flange  16 , a sliding block surface  66  which is tilted or tapered outwards. In this way, the clamp elements  61  can, during closing of the locking device or movement of the flanges  15  and  16  towards one another, can be displaced radially outwards to engage the first locking surface  53  of the flange behind the assigned second locking surface  65  of the clamp elements  61 . 
     The tightening mechanism  70 , as can be seen in  FIGS. 11   a  and  11   n , can include a thread tightener acting between respective opposite ends  62 ,  63  of the chain or belt element  60 . The thread tightener can include a threaded pin  71  arranged in a generally central position. The threaded pin  17  includes oppositely directed threads (e.g., right hand threads and left hand threads or left hand threads and right hand threads) on opposite ends. The thread tightener also includes thread blocks  72  and  73  arranged at the ends  62  or  63  of the chain or belt element  60 , as known per se. A helical gearing is used for operating the thread tightener which contains a gear wheel  74  coupled to the threaded pin  71  in a rotationally locked manner and a worm wheel  75  engaged therewith and coupled to a drive element  80 . 
     By way of non-limiting example, the drive element  80  is a hand twist grip that is coupled to the worm wheel  75  via a ball block. See  FIGS. 12   a - 12   c . The ball block is composed of an inner casing  87  provided with a groove  82 , an outer casing  88  provided with a groove  83  and several balls  81  arranged in between. These balls  81  are deposited in recesses  85  that are embodied in the body  80   a  of the hand twist grip  80 . The inner casing  87  is provided with a push button  84  arranged on an outside and accessible to an operator (see  FIG. 12   a ). The push button  84 , when pressed against the pressure of a spring  86 , acts to release the balls  81  (see  FIG. 12   b ). In this way, the hand twist grip  80  is released for movement outwards due to the action of a spring  89  (see  FIG. 12   c ). As a result, the hand twist grip is displaceable in the direction of its axis of rotation between a lowered position, in which it is secured against rotation, and a raised or not lowered position in which it is released for rotation. In this latter position, the tightening mechanism  70  can be activated via the helical gearing  74 ,  75  and thus the chain or belt element  60  can be released. 
       FIGS. 13 through 15  show a second exemplary embodiment of the invention in which the structural part  20  is a maintenance or inspection cover. A passage opening  28  is provided in the vehicle structure  29  which again is an aircraft. This opening  28  can be closed with the cover  20 . The cover  20  is connected to the structure  29  by hinges  21 ,  22 , which can be the previously mentioned pyramid gears. Through the use of these pyramid gears a virtual axis of rotation lying outside the outer skin of the aircraft is again formed about which the cover  20  can be opened. In this embodiment, however, an opening of the cover  20  is facilitated by resort to a gas pressure mechanism  23  which that acts between the hinges  21 ,  22 . Through the spring force of the gas pressure mechanism  23 , the legs of the pyramid gearings are pressed apart in the area of their swivel axis. This produces an opening movement and causes an opening of the cover  20 . 
     As with the previous embodiment, a first flange  25  is arranged on the structural part or cover  20  and a second flange  26  is arranged on the structure  29  of the aircraft. A locking device in the form of chain or belt arrangement  27  is used essentially in the same way as described for the first exemplary embodiment with reference to  FIGS. 8 through 12 . Here, too, the operation of the chain or belt arrangement  27  takes place by way of a tightening mechanism  70  as previously described. 
     In the third exemplary embodiment shown in  FIGS. 16 through 18 , an inspection or maintenance cover  30  is illustrated. The cover  30  it is attached to the aircraft structure  39  by way of a hinge arrangement which includes hinges  31 ,  31   a ,  32 ,  32   a . Here, too, the hinges  31 ,  31   a ,  32 ,  32   a  are pyramid gears of the previously described type. 
     A gas pressure mechanism  33  is arranged between the springs  31 ,  31   a . The mechanism  33  provides the opening motion of the cover  30 , in the same way as was previously described with reference to the second exemplary embodiment. In contrast to the second exemplary embodiment, however, here two first flanges  35 ,  35   a  are provided on the cover  30  which interact with two second flanges  36 ,  36   a  that are provided on the structure  39  of the aircraft having a passage opening  38 . A chain or belt arrangement  37 ,  37   a  is thus provided on each of the first flanges  35 ,  35   a . Each of these arrangements  37  and  37   a  can be operated by way of a common tightening mechanism  70 . 
     The tightening mechanism  70  is shown in detail in  FIGS. 19   a - 19   c . The general operation is the same as with the tightening mechanism explained with regard to  FIGS. 12   a - 12   c . However, the geometry is slightly different with respect to the position of the closure devices  20 ;  30 .  FIG. 19   b  also illustrates a ball movement BM. 
     Finally,  FIGS. 20-23  shows a passenger aircraft  2  which uses a fourth exemplary embodiment of the closure device  45  according to the invention for opening and closing a passenger door  40 . 
     The passenger door  40  is shown in more detail in  FIGS. 21 through 23 . As was the case in previous embodiments, a passage opening  48  is embodied in the structure  49  of the outer wall of the aircraft  2 . This opening  48  is limited on its circumference by a flange  46 . The closure device, which is partially arranged on the passenger door  40 , includes three flanges  45   a ,  45   b ,  45   c  (see in particular  FIGS. 22   a  and  22   c ). The flange  45  constitutes a first flange provided on the passenger door  40 . A second flange  46  is provided on the structure  49  of the aircraft  2 . Each of these flanges  45  and  46  are composed of several flange portions. In the example shown, these partial flanges are circular flanges. As can be seen in  FIG. 22   a , the flanges  45   a ,  45   b ,  45   c  (and also the flanges  46   a ,  46   b ,  46   c ) lie in different planes which intersect where the parts of the flanges  45 ,  46  touch one another. A chain or belt arrangement  47  has portions  47   a ,  47   b  and  47   c  which are arranged on the flanges  45   a ,  45   b ,  45   c  of the first flange  45 . This arrangement  47  is used to lock the flanges  45  and  46  to each other during closing of the door  40 . The operation is essentially the same as explained with reference to  FIGS. 8 and 9 . Here, too, a tightening mechanism  70  is provided that is used for the common operation of the same. 
     In this fourth exemplary embodiment, the hinge  41 , through which the passenger door  40  is connected to the structure  49  of the aircraft  2 , has the form of a parallelogram hinged joint device in which the first axis and the second axis and the center axis run parallel to one another. 
       FIGS. 24 through 26  show another exemplary embodiment of a closure device according to the invention. In this embodiment, the closure element is a two-leaved landing-gear door. The landing-gear door comprises a first leaf  110  and a second leaf  110   a . Each leaf is respectively attached by hinges  111 ,  112 ,  113  and  111   a ,  112   a ,  113   a  to the structure  119  of the aircraft. In this way, the door can be mounted in a pivoted manner. 
     The hinges  111 ,  112 ,  113 ,  111   a ,  112   a ,  113   a  are formed as pyramid gears of the type described above, and again utilize a virtual axis of rotation X that lies outside the outer contour of the aircraft. As the sectional representation of  FIG. 25  shows, an opening of the leaves  110 ,  110   a  of the landing-gear door takes place about the virtual axis of rotation X, whereby a reciprocal locking and unlocking of the two landing-gear door leaves  110 ,  110   a  is ensured via a center closure  114 . When the landing-gear door  110 ,  110   a  is opened, a passage opening  118  is available and/or used for, e.g. the wheel of an aircraft landing gear to pass through. 
     Respective first flanges  115 ,  115   a  are provided on the outer circumference of the leaves  110 ,  110   a . These flanges  115 ,  115   a  interact with second flanges  116 ,  116   a  arranged on the circumference of the passage opening  118  on the structure  119 . This interaction and the use of a locking device act to lock the landing-gear door. The first flanges  115 ,  115   a  also interact with the centrally arranged center closure  114 . 
     As the enlarged detailed representation in  FIGS. 26   a - 26   c  show, the first and second flanges  115 ,  115   a ,  116 ,  116   a  have on their sides facing one another respective stop surfaces  156  or  157  that rest against one another in the closed state of the landing-gear door leaves  110 ,  110   a . On their sides facing away from one another, they have first locking surfaces  152  or  153  (see  FIG. 26   b ). A number of clamp elements  161  of a chain arrangement  117  (only one of which is shown in section) have second locking surfaces  164  or  165  that interact in a form-locking manner with the first locking surfaces  152  or  153  provided on the first and second flanges  115 ,  115   a ,  116 ,  116   a . The chain arrangement  117  is arranged to run in the radial direction inside the first and second flanges  115 ,  115   a ,  116 ,  116   a.    
     The clamp elements  161  of the chain arrangement  117  are adjustable in their radial position with respect to the center of the leaves  110 ,  110   a  of the landing-gear door between a first position lying radially further inside, in which the first locking surfaces  152 ,  153  of the first and second flanges  115 ,  115   a ,  116 ,  116   a  and the second locking surfaces  164 ,  165  of the clamp elements  161  to release the landing-gear door  110 ,  110   a  are free of one another (see  FIGS. 26   b - 26   c ), and a second position lying radially further outside, in which the first locking surfaces  152 ,  153  of the first and second flanges  115 ,  115   a ,  116 ,  116   a  and the second locking surfaces  164 ,  165  of the clamp elements  161  which lock the landing-gear door  110 ,  110   a  are fixed against one another (see  FIG. 26   a ). 
     As can be further seen from  FIG. 26 , a pressure hose  160 , which can be acted on by a hydraulic or pneumatic work medium, is arranged between the clamp elements  161  and a stop surface  160   a  lying further radially inwards. The clamp elements  161  can be displaced by the hose  160 . The pressure hose  160  is acted on with the drive medium through a pressure medium pump  117   a  (see  FIG. 24 ). When the pressure hose  160  is acted on with the drive medium, a cross-sectional enlargement of the pressure hose  160  causes a radial displacement of the clamp elements  161  to occur from the first position lying radially further inwards (see  FIG. 26   b  and  26   c ) to the second position lying radially further outwards (see  FIG. 26   a ). In the second position, the landing-gear door leaves  110 ,  110   a  are locked to the aircraft structure  119 . When the drive medium flows out of the pressure hose  160 , with a cross-sectional reduction of the hose  160  causes a radial displacement of the clamp elements  161  in the opposite direction from the second position lying radially further outwards (see  FIG. 26   a ) to the first position lying radially further inwards so as to release the lock (see  FIGS. 26   b  and  26   c ). This latter displacement from the locked position to the opened position can be achieved by, e.g., ensuring that the clamp elements  161  are spring-preloaded for a radial displacement from the second position into the first position. In this way, a relief of pressure of the drive medium from the pressure hose  160  causes a displacement of the clamp elements  161  through a spring action. Such movement thus takes place from the second position lying radially further outwards to the first position lying radially further inwards to release the landing-gear door  110 ,  110   a . The clamp elements  161  can thus be displaced by active draining of the drive medium from the pressure hose  160  with cross-sectional reduction of the same to release the landing-gear door  110 ,  110   a  from the second position lying radially further outwards into the first position lying radially further inwards. 
       FIGS. 27   a  and  27   b  show as a further exemplary embodiment a passenger door  140  that is supported in the structure  149  of an aircraft  2  by way of at least one parallelogram hinged joint arrangement  141  which uses two legs coupled flexibly to one another with a first axis  93 , a second axis  94  and a center axis  95  that each run parallel to one another. A second flange  146  is provided on the structure  149  of the aircraft  2 . The flange  146  interacts with a first flange  145  provided on the passenger door  140 . When the passenger door  140  is opened, one can gain access to a passage opening  148 . A chain arrangement  147  is utilized and, as with the previous embodiments, follows a circumference of the passage opening  148 . The arrangement  147  is provided on the second flange  146 , which chain arrangement interacting with the first flange  145  and the second flange  146  causes a locking and unlocking of the passenger door  140 . 
     As the enlarged detailed representation in  FIGS. 28   a  and  28   b  show, the first and second flanges  145 ,  146  have stop surfaces  156 ,  157  respectively on the sides facing one another which rest against one another when the passenger door  140  is closed. On sides facing away from one another, first locking surfaces  152  and  153  are utilized (see  FIG. 28   b ). 
     A number of clamp elements  161  of the flexible chain arrangement  147  (only one of which is shown in section) are used and they have second locking surfaces  164  and  165  that interact in a form-locking manner with the first locking surfaces  152  and  153  provided on the first and second flanges  145  and  146 . The clamp elements  161  of the chain arrangement  147 , which are arranged to surround the passage opening  148  on the structure  149  of the aircraft  2 , are adjustable in their radial position between a first position lying radially further outwards, in which the first locking surfaces  152 ,  153  of the first and second flanges  145 ,  146 , and the second locking surfaces  164 ,  165  of the clamp elements  161  are free of one another to release the passenger door  140  (see  FIG. 28   b ), and a second position lying radially further inwards, in which the first locking surfaces  152 ,  153  of the first and second flanges  145 ,  146  and the second locking surfaces  164 ,  165  of the clamp elements  161  are fixed against one another to lock the passenger door  140  (see  FIG. 28   a ). The chain arrangement  147  is arranged to run radially outside around the circumference of the first and second flanges  145 ,  146 . 
     As in the previous exemplary embodiment of  FIG. 26 , a pressure hose  160  that can be acted on by a hydraulic or pneumatic drive medium is provided between the clamp elements  161  and a contact surface  160   a  lying further outside radially displaced thereto. A pressure medium pump  147   a  is used to act on the pressure hose  160  with the drive medium (see  FIG. 27   a ). When the pressure hose  160  is acted on with the drive medium, resulting in a cross-sectional enlargement of the same, a radial displacement of the clamp elements  161  from the first position lying radially further outwards (see  FIG. 28   b ) to the second position lying radially further inwards (see  FIG. 28   a ) occurs and locks the passenger door  140 . When the drive medium flows out of the pressure hose  160 , resulting in a cross-sectional reduction, a radial displacement of the clamp elements  161  in the opposite direction takes place from the second position lying radially further inwards to the first position lying radially further outwards to release the passenger door  140 . 
     It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  Combat aircraft 
           2  Passenger aircraft 
           10  Radome 
           11  Hinge 
           12  Hinge 
           14  Radome 
           15  First flange 
           16  Second flange 
           17  Chain or belt arrangement 
           18  Passage opening 
           19  Structure 
           20  Inspection hatch 
           21  Hinge 
           22  Hinge 
           22  Gas pressure spring 
           25  First flange 
           26  Second flange 
           27  Chain or belt arrangement 
           28  Passage opening 
           29  Structure 
           30  Inspection hatch 
           31 ,  31   a  Hinge 
           32 ,  32   a  Hinge 
           35 ,  35   a  First flange 
           36 ,  36   a  Second flange 
           37  Chain or belt arrangement 
           38  Passage opening 
           39  Structure 
           40  Passenger door 
           41  Hinge 
           45  First flange 
           46  Second flange 
           47  Chain or belt arrangement 
           48  Passage opening 
           49  Structure 
           52  First locking surface 
           53  First locking surface 
           54  Second locking surface 
           55  Second locking surface 
           56  Stop surface 
           57  Stop surface 
           60  Chain or belt element 
           61  Clamp element 
           62  End 
           63  End 
           64  Second locking surface 
           65  Second locking surface 
           66  Sliding block surface 
           79  Tightening mechanism 
           71  Threaded pin 
           72  Thread block 
           73  Thread block 
           74  Gear wheel 
           75  Drive element, hand twist grip 
           80   a  Body 
           80   a  Ball 
           82  Groove 
           83  Groove 
           84  Push button 
           85  Recess 
           86  Spring 
           87  Inner casing 
           88  Outer casing 
           89  Spring 
           90  Pyramid gear 
           90   a ,  90   b  Hinged joint 
           91  First leg 
           92  Second leg 
           93  First fixed axis 
           94  Second fixed axis 
           95  Swivel axis 
           110 , Landing-gear door 
         
           110 
           a  
         
           111 , Hinge 
         
           111 
           a  
         
           112 , Hinge 
         
           112 
           a  
         
           113 , Hinge 
         
           113 
           a  
         
           114  Center closure 
           115 , First flange 
         
           115 
           a  
         
           116 , Second flange 
         
           116 
           a  
         
           117  Chain arrangement 
           117   a  Pressure medium pump 
           118  Passage opening 
           119  Structure 
           140  Passenger door 
           141  Hinge 
           145  First flange 
           146  Second flange 
           147  Chain arrangement 
           147   a  Pressure medium pump 
           148  Passage opening 
           149  Structure 
           152 ,  153  First locking surface 
           156  Stop surface 
           157  Stop surface 
           160  Pressure hose 
           160   a  Stop surface 
           161  Clamp element 
           164 ,  165  Second locking surface