Title of Invention

"SAFETY BELT TENSIONING DEVICE COMPRISING A TUBE WITH A BOTTLENECK"

Abstract

The invention relates to a safety belt tensioning device comprising a piston which is guided in a tube and, when triggered, is supplied with a gas produced by a gas generator arranged in a tube section, a lateral section introduced into the tube by a cable opening being connected to said piston. The inventive device is characterised in that the receiving section (12) of the tube (10), receiving the gas generator (16), is staggered in relation to the piston stroke section (11) of the tube (10), receiving the piston (17), by means of a narrowing of the cross-section of the tube (10), having a defined overflow course (29).

Full Text

Bended tensioner tube Description The invention relates to a tensioning device for a seat belt with a piston, which is guided in a tube and which in case of triggering is influenced by gas generated by a gas generator located in one section of the tube, to which a section of cable led into the tube by a cable opening is attached. A tensioning device with the aforementioned characteristics is described in EP 1 283 138 Al; the known tensioning device consists of a tube which is bent for better accommodation and assembly in the often limited space available in a motor vehicle for the accommodation of a drive which is necessary for the tensioning process, which exhibits a straight section which accommodates a piston and therefore forms a piston path, and a section which is offset in relation to it which accommodates the gas generator. In the case of the embodiment shown in EP 1 283 138 Al, the tensioning device is provided for a belt buckle, whereby the belt buckle is attached to a cable section or it carried by this. The cable section is deflected in an additionally provided cable deflection area outside the belt tube, guided into the tube by means of a cable opening formed in the walls of the belt tube and is here connected to the piston. In case of triggering, the gas generator generates a drive gas which streams via the bent area of the tube and drives the piston along the piston path, so that the cable section connected to the piston is pulled into the bent tube. By these means, the belt buckle is pulled in the direction of the cable deflection, tautening the seat belt connected to the belt buckle. The known tensioning device is associated with the disadvantage that the pressure of the gas generated by the gas generator is led directly to the piston through the section of the tube which exhibits a cross-section which remains the same. This means that the pressure peak which is created after ignition of the gas generator before the movement of the piston necessitates sufficient strength of the drive cable and stable connection of the cable with the piston as well as a correspondingly good seal of the cable entry into the tube, which gives rise to corresponding costs and effort when designing the known tensioning device. Therefore the invention is based on the task of designing a tensioning device with the generic characteristics in such a way that the loading of the drive cable and further components is reduced, while the tensioning device is manufactured in a simple way. The solution to this task, including advantageous embodiments and further developments, results from the content of the patent claims which follow this description. The basic idea of the invention is that the section of the tube which accommodates the gas generator is offset from the piston path section of the tube which accommodates the piston by a narrowed cross-section created in the tube which has a defined overflow path. The invention involves the advantage that because of the separation of the section which accommodates the gas generator and the piston path section, a sufficiently large pressure can built up in the section for accommodating the gas generator in order to ensure clean and complete combustion of the material which creates the gas, even at low temperatures. Because of the overflow cross-section provided between the aforementioned sections of the tube, no pressure peak occurs in the piston path section, so that thinner drive cables can be used. The pressure losses which occur in the area of the cable seal are correspondingly less. A further advantage consists in the fact that the pressure which applies in the piston path section which affects the piston is maintained over a longer period in an even fashion, as a gas stream is correspondingly fed in from the accommodation section in a regulated and .:• continuous way. Based on the design of the narrowing of the cross-section in relation to the tube which is used, adaptations as regards the design of the tensioning device can easily be made to fit it for its application conditions within a seat belt system. According to one embodiment of the invention it is intended that the narrowing of the cross-section of the tube is effected by deforming the tube. This leads to the advantage of simple manufacturing of the tensioning device without additional devices having to be inserted into the tube. According to alternative embodiments of the invention, the narrowing of the cross-section can be achieved by means of rolling or bending of the tube. In so far as, in a particular embodiment of the invention with a bending of the tube it is provided for that the tube is bent at a bending location using suitable bending tubes which limit the width of the tube during the bending process in such a way that a hollow throat is impressed into the outer wall of the bent tube which exhibits the larger bending radius, and the cable section is deflected via the bent section of the tube, the particular advantage results that because of the tube bend which is created in a particular way and the form of the bent section of the tube, the bent section itself forms the cable deflection, so that a separate cable deflection as a component, and also mounting of such a separate component are not needed, in contrast to the state of the art. The tensioning device can be manufactured with fewer components and therefore altogether more cost-effectively, and finally, the tensioning device according to the invention is compact and can therefore be accommodated in a motor vehicle in space-saving fashion. With regard to the form of the bent section, according to one embodiment of the invention it is provided that the bent inner wall of the tube is brought into contact at the inner side of the hollow throat impressed into the bent outer wall at its narrowest benl point with its inner side, and, in the ears formed on both sides of the narrow throat between outer wall and inner wall, gas guide channels for guidance of the gas from the section of the tube which accommodates the gas generator into the section of the tube which forms the piston path are formed. Based on the bend created in this way, defined cross-sections for the gas guide channels result, which is an advantage for the safe function of the tensioning device. According to one embodiment of the invention it is provided for that the inner angle between the gas generator section and the piston path section of the tube is smaller than the deflection of the cable section, whereby in particular the inner angle can be smaller than 90 degrees. According to one embodiment of the invention it is provided for that the cable opening is located on an area of the tube bend which faces the gas generator. Furthermore it can be provided that in the inner angle of the bent tube enclosed by the inner wall of the tube, fixing means are provided for a fixing part to be fixed to the vehicle. According to one embodiment of the invention it is provided for that the fixing part reaches over the bent tube on the outside in its bending location and forms a guide for the cable section running in the hollow throat on the outer wall of the bent tube. According to one embodiment of the invention it can be provided that the fixing part springs into the inner angle of the bent tube with an interference fit with a projection adapted to the shape of the inner wall of the bent tube which encloses the internal angle and supports the inner wail of the bent tube. This improves fixing of the bent tube and its design in general; Embodiments of the invention are shown in the drawings, which are described in the following text. The drawings are as follows: Fig. 1 a perspective view of the bent tube of a tensioning device, Fig. 2 another perspective view of the Object of Figure 1, Fig. 3 an overall view of the tensioning device as a buckle tensioner, Fig. 4 a schematic side view of the bent area, Fig. 5 a partial cross-section of the bent area, Fig. 6 an enlarged cross-section of the bent area, Fig. 7 an overall view of a tensioning device in the form of a limit fitting tensioner. Fig. 8 the bent tube of a tensioning device in a view according to Figure 1 in a different embodiment, Fig. 9 the form of the narrowed cross-section in the tube according to Figure 8 in an enlarged cross-section. First of all referring to Figures 1 and 2, a bent tube 10 can be recognised as a component of the drive for the tensioning device shown as a whole in Figure 3, whereby tube 10 shown in the embodiment exhibits a piston path section 11 forming a piston path and an accommodation section 12 which accommodates a gas generator. At bending location 13 which separates accommodation section 12 and piston path section 11 from one another, a narrowed cross-section which has yet to be described in more detail, with a defined overflow path for gas generated by the gas generator which is to be introduced into piston path section 11 is formed as gas guide channels 29 (Figure 6). At bending location 13 a hollow throat 14 is impressed into the relevant outer wall with the use of corresponding bending tools for creating the tube bend, and a cable opening 15 for insertion of a cable section yet to be described is formed on the area of bending location 13 which faces gas generator section 12. In the embodiment shown, the tube section following on from bending location 13 of tube 10 is again bent at a further bending location 13a, which does not present an obstacle to the movement of the piston in the assigned piston path section 11. However, the form of bending location 13 is important for the realisation of the invention, and Figures I and 2 are intended to show that following bending location 13 of tube 10, further variations of the design of tube 10 with piston path section 11 are possible. In Figure 3, bending location 13 is now shown in detail along with tube sections 11 and 12 which follow on from it. It can be recognised that in accommodation section 12, a gas generator 16 including corresponding ignition and feed devices is inserted and fixed. A piston 17 is inserted in piston path section 11, to which a cable section 18 is fixed. Cable section 18 runs in the direction of the bending location 13 of tube 10, here passes through cable opening 15 out of tube 10 and then lies on hollow throat 14 formed as a cable guide in the outer wall of the bent tube through the use of a corresponding bending tool. A belt buckle 19 is fixed to the free end of cable section 18 in which a belt tongue 20 is hooked, onto which a seat belt 21 is connected. A fixing part is inserted into the area enclosed by inner walls 24 of the two tube sections 11, 12 of bent tube 10 as fixing part 22, which can be fixed to a fixed part of the vehicle by means of a screw 23. Fixing part 22 is formed in such a way that it supports inner walls 24 of pipe sections 11,12 with an interference fit and engages with a projection 27 into the internal angle 25 formed by the bending process by means of a correspondingly arranged bending tool and thereby fixes bent tube 10 safety to the motor vehicle. Fixing part 22 also reaches over bent tube 10 on its outer side and, in the area of the outer wall of the bent tube, additionally forms a guide 28 for cable section 1 8 running in hollow throat 14. Based on the arrangement of fixing parts 22 in the angle enclosed between inner walls 24 of both tube sections 11,12, the necessary length of the tensioning device is considerably reduced and the entire design and construction of the unit is made considerably simpler. In addition, projection 27, a tab 100 additionally provided on fixing part 22 or other types of stepped additions can serve as anti-rotation devices in relation to the vehicle in order to fix the position of the tensioning device. As can be seen in Figures 4-6, the tube bend is undertaken by use of corresponding bending tools in such a way that at the narrowest bending point the inner side of the associated inner wall 24 of bent tube 10 comes into contact with the inner side of the hollow throat 14 impressed into the bent inner wall 26 with its central area 30, so that ears result on both sides of impressed-in hollow throat 14, which form gas guide channels 29 for guidance of the gas from accommodation section 12 to piston path section 11 of tube 10. In order to achieve such a contour of the inner tube at the bending location when the tube is bent by means of the bending tools applied at internal angle 25 or the outer side, the width of the tube has to be limited by additional tools, as indicated by arrows 36 in Figure 6. In Figure-7;finally an enrbodfment -of"theinventioTris^ sho\vnxvhi'ch'makes it" ' clear that the form of the drive device for the tensioning device with bent tube 10 can also be provided or arranged for connection to a limit fitting. In the case of such a limit fitting 31, the end of the belt strap, not further shown, is fixed to a shaft 34 fixed in a housing 32, which is not turned when the seat belt is in normal use. Only when an accident is detected should the section of the safety belt connected to limit fitting 31 be tensioned, and for this purpose, shaft 34 arranged in housing 32 so as to be rotatable should begin to rotate. This occurs, as shown in Figure 7, through the fact that a cable section 35 is wound onto a shaft extension, whose end is inserted into bent tube 10 in the way already described in Figure 3 and is connected to cylinder 17 located there. When the gas generator is triggered, the piston is driven and unwinds cable section 35 from shaft 34, so that the shaft is turned in the tensioning direction for the seat belt. As can be seen from Figure 7, housing 32 is to be fixed to the vehicle by means of a fixing drilling 33, whereby housing 32 exhibits projection 27 in integral form which projects into the internal angle 25 of bent tube 10 and which therefore fixes the bent tube onto housing 32 of limit fitting 31. In the case of the embodiment shown in Figures 8 and 9, the corresponding narrowed cross-section in the area of bending location 13 is created by means of rolling or shaping, whereby a narrowed section 40 results with an overflow path 41 in its interior. The characteristics of the object revealed in the above description, the patent claims, the summary and the drawing contained in these documents can be of importance both separately and in any combination or combinations with one another for realisation of the invention in its different embodiments. Patent claims 1, Tensioning device for a seat belt with a piston which is guided in a tube and which in case of triggering is influenced by gas generated by a gasf genI'efaTof located in one section ofllie of cable led'into the tube by a cable' opening is attached, charac'teTised-in that the accommodation section (12) of tube (10) which accommodates gas generator (16) is offset from the piston path section (11) of tube (10) which accommodates piston (17) by creation of a narrowed cross-section inside the tube with a defined overflow path (29,41). 2. Tensioning device according to Claim 1, characterised in that the narrowed cross-section is created in tube (10) by means of deformation of tube (10). 3. Tensioning device according to Claim 2, characterised in that the narrowed cross-section is created in tube (10) by deformation by rolling tube (10). 4. Tensioning device according to Claim 2, characterised in that the narrowed cross-section is created in tube (10) by bending of the tube. 5. Tensioning device according to Claim 4, characterised in that tube (10) is bent in such a way at a bending location (13) with the use of suitable tools which limit the width of tube (10) such that in the outer wall (26) of bent tube (10) exhibiting the largest bending radius, a hollow throat (14) is impressed in and cable section (18, 35) is deflected via the bending location (13) of tube (10). 6. Tensioning device according to Claim 5, characterised in that the bent inner wall (24) of tube (10) is brought into contact with its inner side at its central area (30) at the narrowest bending location with the inner side of the hollow throat (14) which is impressed into the bent outer wall (26), and in the ears formed on both sides of hollow throat (14) between outer wall --me'formed foTteadm^ accommodates gas generator (16) into the section (11) of tube (10) which forms the piston path. 7. Tensioning device according to Claim 5 or 6, characterised in that the inner angle (25) between gas generator section (12) and piston path section (11) of tube (10) is smaller, than the deflection of cable section (18, 35). 8. Tensioning device according to Claim 5 or 6, characterised in that the inner angle (25) between gas generator section (12) and piston path section (11) of tube (10) is smaller than 90 degrees. 9. Tensioning device according to any of claims 5 to 8, characterised in that cable opening (15) is arranged on the area of the tube bend facing gas generator (16). 10. Tensioning device according to any of claims 5 to 9, characterised in that in the internal angle (25) of bent tube (10) enclosed by bent internal wall (24) of tube (10), a fixing means (23) for a fixing part (22) which fixes tube (10) to a fixed vehicle part is to be arranged. 11. Tensioning device according to Claim 10, characterised in that fixing part (22) reaches over bent tube (10) at the outside at its bending location (13) and that on the outer wall (26) of bent tube (10) a guide (28) is formed on outer wall (26) of bent tube (10) for cable section (18,35) running in hollow throat (14). 12. Tensioning device according to any of Claims 5 to 9, characterised in that fixing part (22) enters into the internal angle (25) of bent tube (TO)"with a'projecfib'n (27)'¥dapTe3To^ of'b"eTiirtul5ir(TO) angle'(25) W'as to'form'aninterference fit and supports internal wall (24) of the bent tube.

Documents:

7955-delnp-2006-Abstract-(13-02-2014).pdf

7955-delnp-2006-abstract.pdf

7955-delnp-2006-Claims-(13-02-2014).pdf

7955-delnp-2006-claims.pdf

7955-delnp-2006-Correspondance Others-(29-04-2013).pdf

7955-delnp-2006-Correspondence Others-(01-03-2013).pdf

7955-delnp-2006-Correspondence Others-(02-04-2013).pdf

7955-delnp-2006-Correspondence Others-(13-02-2014).pdf

7955-delnp-2006-Correspondence-Others-(14-05-2013).pdf

7955-DELNP-2006-Correspondence-Others.pdf

7955-delnp-2006-Description (Complete)-(13-02-2014).pdf

7955-delnp-2006-description (complete).pdf

7955-delnp-2006-Drawings-(13-02-2014).pdf

7955-delnp-2006-drawings.pdf

7955-delnp-2006-form-1.pdf

7955-delnp-2006-Form-2-(13-02-2014).pdf

7955-delnp-2006-form-2.pdf

7955-delnp-2006-Form-3-(14-05-2013).pdf

7955-delnp-2006-form-3.pdf

7955-delnp-2006-form-5.pdf

7955-delnp-2006-GPA-(01-03-2013).pdf

7955-delnp-2006-pct-notification.pdf

7955-delnp-2006-pct-search report.pdf

7955-delnp-2006-Petition-137-(14-05-2013).pdf

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