METHOD OF SAFEGUARDING A LIQUID IN A TANK AGAINST THEFT, AND FIXING ELEMENT FOR THE EXECUTION OF THE METHOD

Abstract: Method of safeguarding a tank against theft, for example a fuel tank on a vehicle, whereby an expansion element is permanently mounted in the tank's filling stub, said element being arranged to be locked by a spring force and to allow through-flow. The method is characteristic in that before the expansion element is inserted, one sets it in the folded position by means of a fixing element, the strength characteristics of which are reduced by contact with the liquid. A fixing element (5) for the excution of the method is described. The fixing element (5) can be designed for use in connection with an expansion element in the form of a coil spring (4), and be bar-shaped with a transverse hole in each end. For use in the filling stub of a fuel tank, the fixing element (5) can be made of polystyrene. The method according to the invention makes the fitting of the discussed type of theft-safeguard considerably easier than is possible with hitherto-known methods.

Description: METHOD OF SAFEGUARDING A LIQUID IN A TANK AGAINST THEFT, AND FIXING ELEMENT FOR THE EXECUTION OF THE METHOD. The invention relates to a method of safeguarding a tank, for example a fuel tank, whereby in the tank's filling stub there is permanently mounted an expan¬ sion element which is arranged to be locked by a spring force, while at the same time it allows a through flow. The invention also relates to a fixing element for the execution of the method. The safeguarding against theft of tanks by permanent¬ ly disposing a blocking element in the filling stub is known, and many technical solutions have been des¬ cribed. Some of the solutions described can be used only in connection with filling stubs with a special- shape, or at least with a detail of form, for example a change in the internal diameter of the stub, which can ensure that the safeguarding element cannot be displaced in the stub's longitudinal direction, not even when exposed to a quite violent forcible influ¬ ence. Several theft-safeguarding elements are designed with expansion elements which expand under spring force and hook themselves firmly in the internal surface of the stub. Such safeguarding elements are, among other things, described in West German publication 23 60 655 and in Danish Patent Application no. 5183/82, which has been submitted by the petitioner of the present application. The flexibly-expanding and firmly-engaging safeguard- ing elements of known type are so arranged that an expansion element locks the safeguarding element against axial displacement in one direction in the stub. Therefore, two such elements must be used in order to lock the safeguarding element against being pushed into the tank as well as against withdrawal from the stub. That or those spring elements which must serve to lock against a withdrawal movement are simple to con¬ struct, and it is easy to tighten the spring. Norm¬ ally, one can merely press the element into the stub and thereby tighten the spring - this is very clear¬ ly described in Danish Patent Application no. 5183/82. When using corresponding expansion elements to estab¬ lish the locking against axial movement in the direc¬ tion towards the tank, a problem arises with the in¬ sertion and the pre-tensioning of the spring/springs. Three methods used hitherto are described in above- mentioned German publication 23 60 655 and Danish Pat¬ ent Application 5183/82. In 23 60 655, two methods are cited on pages 7 and 8. The first involves the use of (special) clamping pli¬ ers with which one can pre-tension and secure the spring of the expansion element while introducing the safeguarding element into the stub. An alternative method is also described which consists of clamping the spring together before insertion, binding it to¬ gether with a wire or the like, and thereafter - when the safeguarding element has been introduced in¬ to the position in which it is to remain in the stub - to cut the wire or draw it out. _ OMH The Danish Patent Application no. 5183/82 describes that method which is usable with flat, star-shaped springs, whereby one first presses the expansion el¬ ement all the way through the stub down in the tank, and thereafter draw it back to the desired position. All three above-mentioned methods are undesirably difficult--to employ, and there is a great need to find a more simple and sure method of positioning the safeguarding element in the desired position in the stub. The method must not demand that the fitter shall have special tools or special education or training, and neither must it give rise to extra costs of signifi¬ cant extent in .the manufacture of the safeguarding device. The object is achieved according to the invention with a method as presented and characterized in claim 1. Particularly advantageous variants of the main method are described in claims 2, 3 and 4. The advantage of the method described in claim 1 is that under good working conditions, for example in the place where the device for safeguarding against theft is produced, one can pre-tighten and assemble this so that it is completely ready for insertion into the stub. At the same time, in the use of the method there is no need to work with difficult or special tools or to carry out difficult pressing-in or drawing -out movements. Neither is there any necessity for a withdrawal or the cutting over of a spring binding, which easily results in an inaccurate positioning. The only condition for the use of the method describ¬ ed here is that the safeguarding device, also before the pre-tensioned and fixed expansion element is re¬ leased, offers sufficient resistance against axial displacement in the direction towards the tank, so that it is not displaced in this direction by liquid (fuel) flowing in. The method variant which is described in claim 2 is especially advantageous because a bar-shaped element with a hole in each end area is particularly simple and thus inexpensive to produce. Moreover, it is ef¬ fective in connection with a coil spring, the free and pre-tensioned ends of which can hereby be held fixed by mutually serving to counterhold each other. Correspondingly, the variant which is described in claim 3 is expedient in connection with flat or dish -shaped springs with radiate divisions, in that the many spring segments, by fixing with a ring-shaped or tubular fixing element, can in a simple manner create a counterhold for one another. Finally, the method variant according to claim 4 is advantageous in connection with fuel tanks, the rea¬ son being that polystyrene is not dissolved in norm¬ ally-used fuels in such a concentration that it has a detrimental effect on the fuel as such. At the same time, this material also makes possible the cheap production of fixing elements with the desired stren¬ gth and sufficiently quick and sure strength reduction when the element is exposed to the influence of fuel. In the claims 5 to 8 there are described embodiments OVtPI IPO of fixing elements which are of particular advantage in the execution of the method with associated var¬ iants described in claims 1 to 4. Those advantages connected with the individual embodi¬ ments are stated above. In the following, the invention is described in more detail in connection with the drawing, which by way of example shows two advantageous, embodiments of the fixing element according to the invention, and where fig. 1 shows the fixing element according to the invention and used in connection with an expansion element in the form of a coil spring in a device for safe¬ guarding against theft,- fig. 2 shows the safeguard device according to fig. 1 inserted in a stub, and before liquid has flowed through the stub, fig. 3 shows the safeguard device according to fig. 1 inserted in a stub, and after liquid has flowed through the stub, fig. 4 shows a fixing element according to the invention and used in connection with an expansion element in the form of a flat, star-shaped spring mounted in a device for safeguarding against theft, fig. 5 shows the device for safeguarding against theft according to fig. 4 in- OMPI serted in a stub and before liquid has flowed through the stub, and fig. 6 shows the device for safeguarding against theft according to fig. 4 in¬ serted in a stub, and after liquid has flowed through the stub. In figs. 1, 2 and 3, 1 is a device for safeguarding against theft in its entirety, 2 are expansion ele¬ ments which ensure against axial displacement in the direction towards the stub's lead-in opening, which is not shown but which lies to the right, and 3 is the filling stub which is seen in section. 4 is an expansion element in the form of a coil spring which is tightened together with the safeguard device's re¬ maining components, and the free ends of which in figs. 1 and 2 are tightened together and held fixed in the taut state by the fixing element 5 according to the invention. In this case the device safeguard¬ ing against theft is used in connection with a fuel tank, and the fixing element 5 is made of polystyrene which swells when in contact with hydrocarbons, which are the main components in the normal fuels. The fixing element 5 has a simple bar shape, and in each end area of this bar there is a transverse hole through which there is introduced a spring end. Corresponding to figs. 1, 2 and 3, figs. 4, 5 and 6 show a device for safeguarding against theft having a star-shaped expansion element for locking against ax¬ ial movement in the direction towards the tank. OMPI In figs. 4, 5 and 6, the individual components are indicated with reference numbers which are ten great¬ er than the corresponding components in figs. 1, 2 and 3. In figs. 4, 5 and 6, the fixing element 15 according to the invention.is ring-shaped or tubular. For use in connection with a fuel tank, it is expediently pro¬ duced of polystyrene or another material with corres- ponding strength characteristics. If the safeguarding device according to figs. 4, 5 and 6 is to be used in connection with a tank for aqueous products, the fix¬ ing element can, for example, be made of a band, the ends of which are glued together with a water-soluble glue, for example a dextrin-based or a polyvinyl-alco- hol-based glue,- during the formation of a ring. The fixing elements according to the invention are used as described in the method according to the in- vention. It is normally expedient, at the factory at which the theft safeguarding device is produced, for one to pre-tighten that or those springs requiring to be tightened in a tool, and to fix it/them with a fixing element according to the invention. The user is thus able, without any difficulty, to insert the theft safeguarding device in the stub to be safeguard¬ ed. With an expedient embodiment of the safeguarding de¬ vice 1, 11, for example such as that shown, it is merely pushed into the stub 3, 13 to the desired pos¬ ition, after which the tank is filled with liquid. When the liquid flows through the stub 3, 13, the fixing element 5, 15 according to the invention is influenced in such a way that its strength is con¬ siderably reduced, for example by the material swell- ing up, with the result that the spring element 4, 14 is released, the reason being that the fixing el¬ ement 5, 15 is no longer strong enough to resist the pressure from the pre-tensioned spring 4, 14. Hereafter, the expansion element (the spring) 4, 14 can move radially outwards and hook itself firmly into the inner wall of the stub 3, 13. The desired and intended locking against axial dis- placement in the direction towards the tank (to the left in the drawing) is now established completely without difficulty for the fitter. As described earlier, it is moreover necessary for the theft safeguarding device to be formed with such a high frictional resistance against axial movement in the direction towards the tank, that it can resist the through-flow of liquid during normal filling also before the release of the expansion element 4, 14. It will be obvious that many variants and embodiments of the invention as described above and illustrated with two examples can be devised by those familiar with the art, without deviating from the scope of the invention as presented in the claims, which alone define the invention. - T E ζT OMPI

Claims: C L I M S 1. Method of safeguarding a tank against theft, whereby an expansion element is permanently mounted in the tank's filling stub, said element being ar¬ ranged to be locked by a spring force and to allow through-flow, c h a r a c t e r i z e d in that before insertion, one sets the expansion element in the folded position by means of a fixing element whose strength characteristics are reduced by contact with the liquid. 2. Method according to claim 1, used in connection with an expansion element in the form of a coil spring, c h a r a c t e r i z e d in that one fixes the expansion element with a substantially bar-shaped fixing element. 3. Method according to claim 1, used in connection with a substantially disk or star-shaped expansion element, c h a r a c t e r i z e d in that one fixes the expansion element with a substantially ring -shaped or tubular fixing element. 4. Method according to at least one of the claims 1 - 3 and utilized in connection with a fuel tank, c h a r a c t e r i z e d in that one uses a fixing element made of polystyrene. 5. Fixing element for the execution of the method according to one of the above claims, c h a r a c t ¬ e r i z e d in that the fixing element is made of a material which dissolves or swells up in that liquid which is stored in the tank. 6. Fixing element according to claim 5, c h a r - a c t e r i z e d in that it is substantially bar -shaped and provided with at least one transverse hole in each end area. 7. Fixing element according to claim 5, c h a r ¬ a c t e r i z e d in that it is substantially ring -shaped or tubular. 8. Fixing element according to claim 5 , 6 or 7 , c h a r a c t e r i z e d in that it is made of polystyrene. OMPI

Inventors: GANER PEDER, GANER, PEDER
Applicants: LORENZ SVEND AAGE, LORENZ, SVEND, AAGE
Application year: 1984
Main classification: B60K15
IPC codes: B60K15