Abstract:
A device for the protection against the rupture of pipes carrying a fluid includes two or more flow channels and a closing element which interrupts the flow of fluid if a predetermined permissible volume flow is exceeded. At least one of the flow channels can be closed by a test closure in order to increase the flow speed in the remaining flow channels and for test purposes to bring about a movement of the closing element into the closing position. In this way, devices for the protection against the rupture of pipes integrated into complex systems carrying a fluid can be tested in situ to verify their proper functioning.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of International Application No. PCT/EP2010/062332, filed Aug. 24, 2010, which claims priority to German Patent Application No. 10 2009 038 780.3, filed Aug. 25, 2009 and to U.S. Provisional Patent Application No. 61/236,746, filed Aug. 25, 2009, the disclosure of which are all hereby incorporated in their entirety by reference. 
    
    
     TECHNICAL FIELD 
     The technical field relates to a device for ensuring the protection of pipes against rupture, a device for testing a device for the protection of pipes against rupture and also a vehicle having at least one device for the protection of pipes against rupture that is suitable for implementing the process in accordance with the present disclosure. 
     BACKGROUND 
     Numerous examples of apparatus and systems containing pipes carrying liquids include a device for protecting pipes against rupture. These can be found in both household appliances, such as washing machines or dishwashers, and also in more technically complex hydraulic systems in aircraft. There, they are also described by the term “hydraulic fuse”. These devices prevent fluids from escaping completely through these leakage points. Moreover, where they are used in a hydraulic system in an aircraft, their effect is to bring about an automatic shutdown of a defective pipe branching and to ensure that other consumer units upstream of the protection device can still be supplied with hydraulic fluid. 
     Such devices for the protection of pipes against rupture usually include an internal closing element that switches automatically into a closed position once a pre-determined volume flow is exceeded, thus preventing any further loss of fluid. However, when used in particular in an aircraft or in any other system where safety is paramount, the problem arises that such protection devices that are incorporated into hydraulic systems cannot be inspected (in situ). Under normal operating conditions, no volume flow can be generated that can close the pipe rupture protection device. In addition, other demands, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     In one embodiment, this disadvantage is reduced or eliminated altogether, for example, by proposing a device for protecting against pipe rupture, in which a safety inspection can be carried out without the volume flow for the system carrying the fluid exceeding a permissible maximum. 
     An exemplary device for the protection of pipe rupture includes a housing with an inflow and an outflow, with a closing element that is movably mounted in the housing having a front face facing the inflow and a closing face facing the outflow, having at least two flow channels extending from the inflow to the outflow, with at least one orifice arranged in the flow channels for producing a pressure drop in a fluid flowing from the inflow to the outflow and with at least one retaining element arranged between the outflow and the closing element. A device of this nature may have at least one test closure that closes at least one of the flow channels, so that the resulting flow rate is increased in the remaining flow channels, thereby causing the closing element to move into the closed position. 
     The basic functioning of such a device is variously described below. The device in accordance with the present disclosure for protecting against pipe rupture is switched in series with a pipeline, so that in normal conditions the fluid being carried flows unimpeded through the device. A housing inside the device having an inflow and an outflow for the fluid contains a movably mounted closing element. This closing element has a front face that faces the inflow. The closing element also comprises a closing face, which faces the outflow. A fluid flowing through the inflow flows through at least two flow channels around the closing unit towards the outflow and exits at this point. In an area between the closing element and the outflow, there is at least one orifice arranged through which the fluid flows. Because of the increased flow resistance, this causes a pressure drop. This pressure drop is essentially quadratically dependent on the volume flow of the fluid. The pressure of the fluid prevailing at the inflow acts on the front face of the closing element, while the pressure prevailing at the outflow behind the orifice through which the flow has passed acts on the closing face of the closing element in the opposite direction. In addition, the force of a retainer element acts on the closing face, which is also positioned facing the inflow or the front face of the closing element. 
     Under normal conditions, i.e. when the fluid volume flow lies within the normal operating range, an increased force acts on the closing face in such a way that the device in accordance with the present disclosure remains in the open position. The force of the retainer element is calculated in such a way that this additional force increases when a pre-determined maximum volume flow is reached and the force acting on the front face of the closing element corresponds to or slightly exceeds the force acting on the closing face. This results in a movement of the closing element into a closing position. 
     The force excess on the front face can be explained by the fact that, as mentioned above, the pressure drop through the orifice between the closing face and the outflow is essentially quadratically dependent upon the volume flow. Therefore, as the volume flow increases, the resulting pressure differential between the inflow pressure and the outflow pressure also increases, so that, at a given volume flow, the inflow pressure is sufficiently high in relation to the resetting force acting on the closing face to move the closing element into its closing position. 
     The number of flow channels within the device in accordance with the present disclosure is neither strictly stated nor limited. However, for the purpose of technical manufacturing simplicity, it could be appropriate to use two or four flow channels. Clearly, there could be three, five, six or more flow channels, which could be combined with a test closure. In a typical use of two flow channels, closing one of the flow channels would have the effect of doubling the flow speed in the other channel and increasing the resulting pressure drop through the orifice by a factor of four. This fluid volume flow between the inflow and the outflow could in itself be sufficient to generate a force excess at the front face and to move the closing element into its closing position. 
     Unlike conventional devices already known to the state of the art, devices in accordance with the present disclosure may include a test closure arranged in the housing, which can close at least one flow channel in order to increase the resulting volume flow, that is to say the flow speed, in the other flow channels. As a result of the relationship between the flow speed and the pressure drop, the closure of one flow channel will result in a significantly greater pressure drop through the orifice between the inflow and the outflow and produce a force excess at the front face of the closing element, thereby moving the closing element into its closing position. By closing the test closure a state is achieved inside the device in accordance with various embodiments that brings about the closure of the device. 
     This structurally simple solution is a very effective method of testing the functioning of a device for ensuring the protection of pipes against rupture in situ, without any need to dismantle the system or take it apart. This saves the operator of a safety-relevant system, for example, the operator of an aircraft with at least one safety-relevant hydraulic system or other systems, considerable maintenance costs without having to increase the complexity of the system or the plant. 
     In order to prevent a situation in which, because of any dynamic effects from the rapid opening and closing of valves or the like, the device in accordance with the present disclosure may briefly close, the closing element can be movably housed in a bushing section within the housing, so that sufficient fluid may flow into the bushing section to maintain the constancy of the volume so as to actuate the closing element. This flow of fluid can be limited by a cover for the bushing section arranged on the front side of the closing element having an integrated choke directed towards the inflow, so that the movement of the closing element is damped. When the maximum volume flow is reached or exceeded and a force excess is present at the front face, the closing element is forced into its closing position, whereby the space formed between the closing element and the cover slowly fills with fluid thus limiting the speed of the closing element. In this way, pressure or flow peaks can be absorbed. 
     It is conceivable that a number of test closures could be provided for a number of flow channels, so that two or more test closures would need to be closed in order to be able to conduct a functioning test. 
     In a particularly advantageous embodiment, the test closure is movably arranged on the housing so that by moving it into a closing or an opening position, the flow channel is correspondingly closed or opened. 
     In a further embodiment, the test closure could be mounted in such a way that it can be rotated and include a closing face, which closes in such a way that it is flush with a surrounding wall of the respective flow channel and in a closing position closes the respective flow channel. The closing position could be achieved by starting from the closing position with a rotation of the test closure through an angle of rotation of 180°. 
     In a further embodiment, it could be an advantage that the test closure can be deflected longitudinally into the respective flow channel, so that—for example—a closing or opening of the respective flow channel can be effected by pressing or pulling. For this purpose, the test closure could be spring-mounted and could be released again once the closing position of the closing element has been reached. 
     In another embodiment, the test closure is so designed that a colored warning sign is visible when it is in its closing position, thus giving a warning before the device is used. 
     It is also conceivable that the test closure could be operated and locked without being activated, possibly for safety reasons or because under pressure the forces required to activate it were too high. At the end of the test, the device would need to be reset by hand. The special tool required for this purpose could be marked for example with an elongated red warning flag, as is customary in aviation. 
     Moreover, it could be especially advantageous if the test closure were mechanically constructed in such a way that it could only be switched into a closing position by using a special tool and this special tool could only be removed from the test closure if the latter is in an opening position. This would be especially effective in preventing an involuntary closing of the test closure. 
     A process for the testing of a device for the protection of pipes against rupture is also disclosed, which comprises the steps for operating the higher level system, for closing at least one test closure, for closing down the entire system when the closing position of the closing element is reached, and a final optional operation of the higher level system. 
     A device is also provided for protecting pipes against rupture in an aircraft and also by an aircraft having at least one hydraulic system and at least one device in accordance with the present disclosure for the protection of pipes against rupture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features, advantages and possible applications of the present disclosure will become apparent from the following description of the different embodiments and the drawings. At the same time, all features that are described and/or depicted in the drawings may be used both individually and in any combination in the context of the present disclosure regardless of the manner in which they are presented in the individual claims or of their retroactive applications. The drawings also contain the same reference symbols for the same or similar objects. 
         FIG. 1  is an illustration of a device in accordance with an embodiment in a lateral sectional view; 
         FIG. 2  is an illustration of the process in accordance with an embodiment in a schematic block diagram; 
         FIG. 3  is an illustration of an aircraft having at least one hydraulic system and at least one integrated device in accordance with an embodiment for the protection of pipes against rupture; and 
         FIGS. 4   a  to  4   c  show various exemplary test closures. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a lateral section of a device in for the protection of pipes against rupture  2 , which includes a housing  4  having an inflow  6  and an outflow  8 , a locking element  10  that is arranged in a movable manner in a bushing section  12 , a front face  14  and a closing face  16 . In the housing  4 , there is also a retaining element  18 , which is supported through a spring  20  against the housing in the vicinity of the outflow. Between the locking element  10  and the retaining element  18  there are number of orifices  22 , which produce a pressure drop in one of the fluids flowing from the inflow  6  to the outflow  8 . 
     Between the inflow  6  and the orifices  22 , two flow channels  24  and  26  can be seen in this drawing, although more flow channels can also be arranged in the housing  4 . If fluid flows through the inflow  6  into the two flow channels  24  and  26 , it passes through the orifices  22  and in so doing it undergoes a pressure drop. Effectively, this pressure drop increases quadratically in relation to the flow speed within the flow channels  24  and  26  with the result that, for example, if the volume flow is doubled, a four-fold pressure drop can be expected through the orifices  22 . 
     Along the plane of the drawing, the locking element  10  can move to the right towards the outflow  8 , whereby, when it reaches the edges  28 , it reaches a closing position in which the orifices  22  are closed, so that the flow of fluid between the inflow  6  and the outflow  8  is completely interrupted. The movement of the locking element  10  into this closing position is brought about by the increasing pressure difference between the pressure level at the inflow  6  and the pressure level at the outflow  8 . If the force at the front face  14  of the locking element  10  exceeds the resetting force acting on the closing face  16  produced by the pressure at the outflow  8  and the spring  20 , the closing element is forced into its closing position. This position may be left again if the fluid pressure is interrupted at the inflow  6 . 
     For compensating pressure or flow peaks caused by rapid opening and closing movements of valves or the like in a hydraulic system, a cover  32  comprising a choke system is arranged on the bushing section  12 . If the locking element  10  is forced into its closing position, the hollow space located between the locking element  10  and the cover  32  must fill up with fluid in order to preserve the volume constancy in order to permit a movement of the locking element  10 . The choke  30  can be designed in such a way that a damping effect on the movement of the locking element  10  can be achieved very easily and, in an ideal case, this can compensate for pressure or flow peaks at the inflow  6 . 
     In order to enable the device in accordance with the present disclosure to be tested, a test closure  34  is arranged on the housing  4  which can close the upper flow channel  26 . This is effected by the test closure  34  having a closing face  36 , which in an opening position of the test closure lies flush with a wall  38  of the flow channel. When the test closure  34  is rotated in its opening position through 180° through its own axis, the closing face  36 , depending on the corresponding geometric design of the test closure, turns in such a way that the flow channel  26  is completely closed. For this purpose, the flow channel  26  could have a section, the central axis of which forms an angle of 45° with the longitudinal axis of the device in accordance with the present invention, so that the closing face  36  is also at an angle of 45°. When rotated through an angle of 180°, the closing face  36  extends vertically to the wall  38  and then covers the entire cross-section of the respective flow channel  26 . 
     If the test closure  34  is moved into a closing position, the volume flow in the upper flow canal  26  comes to an end, with the result that the entire fluid flow passes through the lower flow channel  24 . This assumes that the device  2  comprises only two flow channels,  24  and  26 . The pressure loss at the orifices  22  increases by a factor of four because the flow speed has now doubled. Given an appropriate design of the spring force, this significantly higher pressure loss could be sufficient to build up a force excess at the front face  14  of the locking element  10 , leading to the locking element  10  being moved into its closing position. 
     The drawing is only intended to be an example, so that the number of flow channels arranged in the housing  4  could be increased. Similarly, any number of test closures could be distributed along the flow channels and these could even function on the basis of different operating principles. In this way, test closures could be imagined that are pressed into a corresponding flow channel  22 . 
       FIG. 2  illustrates an exemplary method in accordance with an embodiment in the form of a block diagram. After the initiation  40  of the operation of a higher level system, for example a hydraulic system, all existing test closures  34  will be closed  42  one after another and the reaction of all devices  2  that are arranged in the higher level system will be tested  44 . After this test has been completed, the operation of the higher level system will be interrupted  46 , so that the locking element  10  of each of the devices  2  will be moved in the direction of the inflow  6 . Subsequently, a new initiation  48  of the operation of the higher level system can take place. 
     Furthermore,  FIG. 3  shows an aircraft  50  that is equipped with at least one hydraulic system  52 , on the pipe system of which  54  a device for the protection of pipes against rupture in accordance with one embodiment has been arranged. 
       FIG. 4   a  illustrates a test closure  56  having a bevelled and rotatably mounted closing body  58 , which can be rotated into either an opening or a closing position. This principle corresponds to the test closure  34  shown in  FIG. 1 . A further special feature is a slotted bushing  60 , which protects an operating end  62  of the test closure  56  from any unauthorized or unintentional operation. With the use of an appropriate tool  90 , the operating end  62  can be engaged and the test closure  56  can be operated. In one example, the test closure  56  is constructed in such a manner that it can only be brought into a closing position through the use of the special tool  90  and this special tool  90  can only be removed when the test closure  56  is in an opening position. 
       FIG. 4   b  shows a further possible test closure  64 , which has a closing element  66  that can be pressed into position. The test closure  64  can be operated by an operating end  68  in the form of a button, for example. In one example, the test closure  64  is spring-mounted with a spring  92  and without any external influence reverts independently from its closing position to its opening position. 
     Furthermore,  FIG. 4   c  shows an addition test closure  70 , which, by being rotated over a milled recess  72 , into which a pin  74  engages, pivots a closing element  76  in an axial direction. 
     All these examples are to be understood as being exemplary. It is understood that appropriate sealing rings  78  or the like are used for sealing purposes. 
     Finally, it must be stressed that the terms “comprising” are not intended to preclude other elements or steps and that “a” or “an” do not preclude a plural form. It is also stressed that features or steps, described by means of references to one of the above embodiments, can also be used in combination with other features or steps of other embodiments described above. Reference marks contained in the claims are not to be seen as being a limitation. Moreover, while at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.