Abstract:
A safety system for prevention of the escape of noxious media, such as explosive gas mixtures and/or ignitable substances, has at least one interception element ( 10; 30 ) which at least partly encloses and seals off a potential escape point ( 12 ) for the medium. The medium is precipitated onto the interception element ( 10; 30 ). Once the medium has been collected, it may be removed from the interception element ( 10; 30 ). In this way, both aggressive media and fuel-laden gases may be effectively controlled by safety engineering measures.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a safety system for preventing escape of noxious media, such as explosive gas mixtures and/or inflammable substances, having at least one interception element. The interception element at least partly encloses and seals off a potential escape point of a particular medium. The medium is precipitated onto the interception element, is collected in this interception element, and may be removed from it. The present invention also relates to a process for operation of the safety system. 
   BACKGROUND OF THE INVENTION 
   Interaction of structural components, in particular, to conduct fluid constantly results in unintentional development of potential points of leakage of noxious media which escape from the fluid conduct system. The escaping media is often in the form of clouds of gases as aggressive media vapors (acids, lyes, toxic substances, etc.) or explosive gaseous mixtures and/or easily ignitable substances that constitute a safety hazard for the surroundings, including the harmful effect on the environment. Such problematical situations arise in chemical processing technology, in particular, in refining of fuel and its delivery by dispensers, in hydraulic systems, and especially in operation of diesel engines and other internal combustion engines. 
   SUMMARY OF THE INVENTION 
   The safety system and process for its operation of the present invention is intended to address this leakage problem. In the present invention, hot, gaseous, noxious media, possibly and unintentionally escaping from a potential escape point, undergo condensation at an interception element. The condensate may then be reliably and removed with precision from the interception element, without the possibility of the escaping medium coming in contact with the environment. Consequently, not only may aggressive media such as gasiform acids, lyes, or poisons be intercepted and controlled, but fuel-laden gases such as hot, fuel-saturated air can also be controlled, without potentially coming into contact with other hot structural elements, such as engine or exhaust gas components (turbochargers). Such contact could set off a fire or even an explosion in a vehicle, such as a passenger car, truck, or bus, and even aboard ships. 
   The person skilled in the art of such safety engineering is or would be surprised to learn that it is possible, by providing a condensate intercepting element in the vicinity of a danger point, to trap and remove noxious media with precision by condensation without the need for significant equipment engineering safety design effort. The present invention is cost-effective and ensures ease of access to potential areas of leakage, permitting additional cost reduction. 
   In one especially preferred embodiment of the safety system, a protective element interrupts the direct path of impact of the medium between the escape point and one interception element, and is present as spray protection between one interception element and the escape point as additional interception element. If the medium with damaging potential escapes from a leakage or escape point, it may do so initially in the form of a fluid under high pressure and at a high temperature so that it would be difficult to control such a stream, even one in the form of an individual or spray component, by the interception element of the safety system described in the foregoing. In order to cope with such extreme cases as well, the protective element forms an obstacle to the fluid components of the medium as additional interception element, preferably one configured as a temperature-stable protective cap. These components are then retained. Only the gas components and gas mixtures of the leakage flow come into contact with the one interception element. A condensate is formed. A redundant safety structure in the form of a multishell system is formed in this manner. 
   The safety system of the present invention has proved to be well suited in particular for an operating process in which pollutants are present in an exhaust gas system, ones such as soot particles resulting from diesel fuel combustion. The pollutants are postcombusted by fuel injection. Hot fuel-saturated air escaping from an escape point of the exhaust gas system, which is unintentionally present, is precipitated onto the interception element of the safety system and is removed from this interception element as condensate. Consequently, by applying the process technology including employment of the safety system of the present invention, it is possible, for the purpose of complying with higher exhaust gas standards, to postcombust any soot components of diesel fuel and the like arising in an exhaust system of a vehicle. Any hot fuel-saturated air unintentionally occurring as a result of leakages is intercepted by the safety system and neutralized so that the gases or vapors involved may not come into contact with other hot engine and exhaust gas components to form foci of fires or explosions. 
   Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
       FIG. 1  is a front perspective view, not to scale, partly cutaway, of the basic structure of the safety system according to one embodiment of the present invention; 
       FIG. 2  is a perspective top view of the lower part of the safety system of  FIG. 1 ; 
       FIG. 3  is an unfolded perspective view of a part of the safety system shown in  FIG. 2 ; and 
       FIG. 4  is a perspective front view of the closed safety system shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The safety system illustrated in the drawings prevents escape of noxious media, such as explosive gas mixtures and/or combustible substances, particularly ones in the form of easily combustible fuels or the like. The safety system of the present invention has an interception element  10  enclosing at least in part a potential escape point  12  of the medium. If an unintentional escape of a medium occurs, the medium can be precipitated onto the interception element  10 , in particular causing it to undergo condensation and be collected in the interception element  10 , and then removed from it. Consequently, the interception element  10  makes certain that media harmful from the viewpoint of safety engineering neither can escape into the environment nor can harm the environment and/or be ignited on other hot components of a fluid-conducting system (not shown), such as process engineering equipment, hydraulic assemblies, or internal combustion engines including diesel engines, etc. 
   The interception element  10 , configured as a trough, encloses the potential escape point  12  for the medium at a prescribed distance such that the medium to be intercepted, if present in the form of saturated air or gas, is at least partly condensed and precipitated onto a wall  14  of the interception element  10  and received as condensate in a collecting element  16  of the interception element  10  for removal. As shown in the overall view in  FIG. 1 , the interception element  10  is configured to be integral with the collecting element  16  as a molded sheet metal element. Preferably, a multi-component configuration, as shown in  FIGS. 2 to 4 , is used for the safety system. The trough-like collecting element  16  is provided at its deepest point with an outlet or return line  18  which receives the condensate components, including any pollutants, and other residues from the safety system for specific further use such as for return to a system tank, a collecting unit, or the like (not shown). 
     FIG. 1  illustrates use of the safety system for an exhaust gas system  20  of a diesel engine (not shown). The part of the exhaust gas system  20  shown in  FIG. 1  has an injection valve or an injection nozzle  22 . The one free end of nozzle  22  communicates with a combustion space (not shown), and is enclosed in a nozzle or combustion chamber  24  that is a component of a larger combustion system (not shown). The free end of the injection nozzle  22  shown in  FIG. 1  is connected to a fuel line feeding the injection nozzle  22 , and makes certain that injected fuel can reach the combustion chamber and its combustion space. 
   The configuration as described serves the purpose of post-combusting the soot or other pollutant components remaining in the exhaust gas flow of a diesel engine by the fuel injected and ignited by the injection nozzle  22 . The post combustion allows compliance with the higher and very strict exhaust gas standards expected in the future, something which has not been possible with conventional catalyst systems. Application of post combustion, as described, does not, however, exclude the possibility of unintentional formation of at least one escape point  12  by leakage points, as, for example, between the injection nozzle  22  and the wall components of the combustion chamber  24  shown in  FIG. 1  to which the injection nozzle  22  is joined, preferably by a screw connection. The possibility is not to be excluded that the injection nozzle  22  might be loosened by engine vibrations or be canted when inserted in assembly processes so as to create a potential escape point. In this instance, the hot fuel-saturated air arising in post combustion would then escape fuel injection, accordingly escape from the combustion chamber  24 , and might then be ignited on other hot engine or exhaust gas components, for example, creating possible sources of explosion in addition to sources of fire. The trough-like interception element  10  acts to prevent such situation in that it makes it possible to condense the hot fuel-saturated air there. The condensate, predominantly in the form of fuel droplets, may then be moved downward by the force of gravity along the interior wall  14  of the interception element  10  to the collecting element  16  as a collection container, and leave the interception element  10  in the manner already described. 
   The trough-like collecting element  16  is fastened for assembly of the interception element  10  on parts of the combustion chamber  24  by nuts  28  tightened in the chamber structure.  FIG. 2  in particular illustrates nut  28 . Another fastening nut is positioned on the diametrically opposite edge of the trough and not illustrated. In addition to its collection function, the collecting element  16  forms, determined by the temperature relationships, thermal shielding of the injection system. For this purpose, the collecting element  16  preferably is configured as a shaped metal element such as a deep-drawn part, and may also have a structure comparable to that of known thermal shield structures in this area. 
   A protective element  30 , preferably in the form of a spray or injection shield, blocks the direct path of impact of the medium between an escape point  12  and one interception element  10 , and is mounted as additional interception element between the interception element  10  and the escape point  12 . The structure of the protective element  30  is shown in greater detail in  FIG. 3 . In  FIG. 3 , the protective element  30  has two flap elements  32 ,  34  positioned adjacent to each other along a common bending or fold line  36  to form a cylindrical receptacle space  38  ( FIG. 1 ). Flap elements  32 ,  34  may be folded toward each other and joined together by a conventional screw connection  40  (see  FIG. 2 ). As shown in  FIG. 2 , the protective element  30  extends more or less perpendicularly relative to the trough bottom  42  of the trough-like collecting element  16  from the trough bottom  42  to the trough edge  44 . Flanged or beaded wall elements  46  of trough edge  44  are applied of the lower part of the interception element  10  to effect sealing ( FIG. 4 ). 
   As seen in  FIG. 3  in particular, the flap element  32  has, in an impressed recess, a strap-like or clamp-like seal  48 . The other, second, flap element  34  has, in the area of penetration or opening  50  for the fuel line  26 , a piece of a seal  52  in the form of a segment of a ring. The receptacle space  38  made up of and between the two flap elements  32 ,  24 , one superimposed on the other, is sealed off from the environment in the area of the fuel line  26 . The medium emerging from the escape point  12  would first be precipitated against the interior wall  54  of the protective element  30  after this element has been installed. Fluid (diesel fuel) escaping in the form of a stream in particular can accordingly be effectively intercepted. If gaseous media components escape downward from the protective element  30 , as viewed in  FIG. 1 , since the seals  48  and  52  are interrupted at the lower escape point, the upper part of the interception element  10  would cause formation of condensate in addition to performing the collection function. In addition to the potential escape point  12 , the possibility also exists, of course, of formation of other escape points, such as ones in the area of transition from fuel line  26  to injection nozzle  22  or injection valve. 
   The protective element  30  preferably performs its function together with the interception element  10  as illustrated in the diagram, as determined by the specific application. However, the possibility generally also exists of omitting the protective element  30  and having the decisive protective function performed exclusively by the interception element  10 . It is also conceivable that in the configuration shown in  FIG. 2 , the upper part of the interception element  10  could be omitted and the protective element  30  could operate in conjunction with the trough-shaped collection element  16  as an effective interception element. In such event, the cap-shaped protective element  30  would to a great extent have to ensure the condensate formation. 
   In the case of increased safety requirements, which generally are to be assumed to exist, the safety system as described in the complete illustration in  FIG. 4  would have to be in operation. To provide effective sealing between collection element  16  and upper cap element of the interception element  10  to this end, the collection element  16  has circumferentially in the transitional area, between trough edge  44  and recessed collection point, a circumferential annular seal  56  ( FIG. 2 ). Seal  56  in turn fits into a recess in the collecting element  16 . To achieve complete sealing in the area of the outlet or return line  18 , the upper trough element of the interception element  10  has a corresponding segment-like seal (not shown) in a corresponding channel-shaped area recess of the second flap element  34  comparable to the annular segment seal  52 . By preference, the seals are mounted to be captive inside the system elements of the safety system. 
   On the whole the interception element  10 , with its two trough-like upper and lower cover elements, functions as temperature shield of the injection system in relation to any possibly adjacent exhaust gas system used, for example, for a turbocharger of a diesel engine or the like. A conventional screw connection  58  (see  FIG. 4 ) is used to connect the upper cover of the interception element  10  to the lower cover in the form of the collecting container  16 . 
   As a rule, the safety system of the present invention may be used, in addition to the fuel injection for post combustion of diesel soot particles, for other areas relevant to safety engineering, and in particular always where gasiform media representing a potential hazard are to be intercepted before entering the environment. In this respect, the present safety system may optionally be used as a cost-effective replacement of conventional filter systems. 
   While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.