Tensioning device for a seat belt component

Abstract

Tightening device for a seat belt component, comprising: a gas generator (1) for generating a pressurized gas, a piston (2) driven by the pressurized gas, a pull rope (3) connected to the piston (2) which can be connected to a seat belt component to be set into a tightening movement, a tightening tube (4) for receiving and guiding the piston (2), a guide element (7) for the pull rope (3) arranged at least partially in the tightening tube (4), wherein the guide element (7) seals around the pull rope (3) on its side facing the piston (2) with a sealing section (9), wherein the piston (2) rests against the guide element (7) in an initial state, wherein the guide element (7) has a contact section (10) on its outer circumference facing an inner surface of the tightening tube (4) and the piston (2) rests against the contact section (10) in the initial state, characterized in thatthat the system section (10) protrudes axially beyond the sealing section (9) in the direction of the piston (2).

Description

The present invention relates to a tightening device for a seat belt component, having a gas generator for generating a compressed gas, a piston which can be driven by the compressed gas, a pull cable which is connected to the piston and can be connected to a seat belt component which is to be set into a tightening movement, and a tightening tube for receiving and guiding the piston.Such a tightening device is known, for example, from DE 10 2015 111 083 B4, in which the piston is guided in a tightening tube. The tensioner tube is connected to a deflection block produced in a die casting process, which deflection block forms a cable deflection for the pull cable and forms a receptacle for the gas generator and a pressure chamber into which the compressed gas generated by the gas generator flows. The deflection block connected to the end face of the tensioner tube requires a component that is relatively expensive to produce and that also requires a relatively high space.From WO 2021 / 160 569 A1, therefore, a tightening device is known, in which the gas generator is arranged within the rectilinear tightening tube. In the jacket of the tensioner tube, a recess is formed, through which the pull cable is led out of the tensioner tube. For guiding the pull cable out of the tensioner tube, a cable deflection is disclosed which is embodied in multiple parts, wherein a component referred to as a guide part with a receptacle for the gas generator can be pushed into the tensioner tube and a component referred to as a fixing part protrudes from the outside through the recess, so that the pull cable is guided through the recess by means of the fixing part also referred to as cable guide below.A tensioning device having the features of the preamble of the independent claims is known from DE 10 2014 002 006 A1.The guide part has at its end facing the piston a sealing section which sealingly surrounds the traction cable so that in the case of release no compressed gas can escape through the guide part and the cable guide along the traction cable. The sealing section also serves as a contact / stop for the piston during the assembly of the tightening device. Namely, during assembly, the piston is brought into abutment with the sealing portion of the guide member, so that a predefined position for the piston is given by the sealing portion. Thus, the sealing section according to WO 2021 / 160 569 A1 performs two functions, namely sealing the pressure chamber and providing a stop. However, the abutment of the piston to the sealing portion during assembly may cause the sealing portion to be damaged, so that the sealing function is impaired. Moreover, when the sealing portion is made elastic, the position of the piston is not accurately predetermined in the initial state of the tightening device.It is therefore the object of the present invention to at least partially eliminate the disadvantages explained with reference to the prior art and in particular to specify a tightening device in which the escape of compressed gas is reduced and / or in which the position of the piston in the initial state is more precisely predefined.A possible solution for the object is specified with the tensioning devices having the features of claims 1 and 2, wherein further solutions and advantageous developments of the tensioning device are explained in the preceding and following description and in the dependent claims, wherein individual features of the advantageous developments can be combined with one another in a technically expedient manner.The object is achieved in particular by a tensioning device for a seat belt component having the features mentioned at the beginning, wherein a guide part is arranged at least in sections, preferably completely, in the tensioning tube and the guide part sealingly surrounds the pull cable on its side facing the piston by means of a sealing section. Furthermore, it is provided that the guide part has an abutment portion on its outer periphery facing an inner surface of the tensioner tube, wherein the piston abuts the abutment portion in the initial state.In other words: The invention provides in its basic idea that the one-piece guide part has two sections arranged separately from one another, so that the first section, which is referred to as the sealing section, provides the sealing function with respect to the traction cable, and the second section, which is referred to as the contact section, provides the function of a stop for presetting a position of the piston in the initial state. In this case, it is provided in particular that the contact portion is offset outwards in the radial direction (with respect to the longitudinal axis of the tensioner tube) with respect to the sealing portion which encloses the pull cable centrally in the tensioner tube. By separating the function of providing a seal and providing a stop at different portions of the guide part, on the one hand, the risk of leakage of compressed gas is reduced and, on the other hand, a more accurate stop for the piston in the initial state is predefined.In order to specify the position of the contact section even more precisely when the guide part is inserted into the tensioner tube, it is proposed that the contact section of the guide part in the initial state bears against the inner surface of the tensioner tube. The contact section of the guide part is thus dimensioned such that in the initial state it is in contact with the inner surface of the tensioner tube. When the abutting portion abuts the inside of the tensioner tube, the abutting portion cannot be deformed radially outward when the piston is mounted.In principle, the geometry of the piston and of the guide part must be matched to one another in such a way that the piston can come into contact with the contact section in the initial state. For this purpose, it can be provided, for example, that the piston has a sleeve-shaped section which extends, in particular radially on the outside, in the axial direction over the sealing section. In this case, the sleeve-shaped portion of the piston would surround the sealing portion. However, it is preferable that the abutting portion protrudes in the axial direction toward the piston via the sealing portion so that the contact point between the piston and the abutting portion is offset in the axial direction from the sealing portion. In this case, therefore, the region of the guide part forming the contact section surrounds the sealing section.In principle, it is sufficient if the sealing section forms a plurality of discrete contact points for the piston. However, it is preferred that the sealing portion is shaped such that a closed, annular contact point for the piston is formed.In order to ensure even more successfully that the sealing function of the sealing section is not impaired by the piston, it is provided in one embodiment that the sealing section in the initial state is spaced apart from a section of the piston which directly surrounds the traction cable, preferably at least 1 mm, particularly preferably at least 3 mm, in the axial direction. Thus, the piston generally has a mushroom-shaped configuration, wherein a tubular central portion encloses the pull cable and extends along the pull cable in the direction of the sealing portion. The end face of this tubular section of the piston facing the sealing section is in the initial state clearly spaced from the sealing section of the guide part, while the piston rests with its mushroom-shaped region against the contact section of the guide part.The invention relates in particular to such tightening devices in which the tightening tube has a recess in its jacket between the gas generator and the piston and in which the tightening device comprises a cable guide which projects through the recess into the tightening tube and with which the cable is guided through the recess. The deflection block produced by means of die casting can thus be dispensed with.It is provided in particular that the cable guide engages with its section engaging into the tensioner tube into the guide part, whereby on the one hand the guide part is fixed in its position in the tensioner tube and on the other hand a passage of the pull cable through the recess is made possible without the pull cable coming into contact with an edge of the recess formed by the tensioner tube.The gas generator is arranged in particular within the tensioner tube, wherein it can preferably be provided that the guide part has a receptacle, wherein the gas generator is arranged in the receptacle. In this context, it is provided in particular that the guide part is designed such that the compressed gas generated by the gas generator is guided along the pull cable within the tensioner tube to the piston without the pull cable being acted upon by the compressed gas in the region of the guide part.The recess for the traction cable and the cable guide is arranged in particular in a rectilinear section of the tensioner tube, wherein it is provided in particular that the tensioner tube is rectilinear over its entire extent.The invention and the technical field are explained below by way of example with reference to the figures. They show schematically FIG. 1 : an exploded view of a tightening device, FIG. 2 : a sectional representation along the longitudinal axis of a tensioner tube through the tensioning device, and FIG. 3 : a detailed view through the tightening device in the sectional representation.The tightening device illustrated in FIGS. 1 and 2 comprises a tightening tube 4 and a pull cable 3 for a seat belt component. The tensioner tube 4 is formed with a recess 5, through which the traction cable 3 is guided by means of a cable guide 6. A piston 2 is arranged on the traction cable 3 inside the tensioner tube 4, wherein a fastening 8 is pressed with the traction cable 3 and abuts the piston 2. Inside the tensioner tube 4 there is also arranged a guide part 7 which forms a receptacle for a gas generator 1. In the assembled state, the gas generator 1 is thus also arranged in the tensioner tube 4.As can be seen in particular from FIG. 2, the cable guide 6 engages in the guide part 7 in the assembled state, wherein the cable 3 is guided through the guide part 7.In the event of deployment, the gas generator 1 generates a compressed gas which is conducted along the pull cable 3 to the piston 2 by the guide part 7 without coming into contact with the pull cable 3. Due to the compressed gas, the piston 2 is driven (to the right in FIG. 2 ), wherein the piston 2 rests on the fastening 8 on its end facing away from the gas generator 1. With the tensioning device, a seat belt component (such as a terminal fitting or belt buckle) that can be connected to the pull cable can thus be pulled in.As can be seen in particular from FIG. 3, the guide part 7 has a sealing section 9 which surrounds the traction cable 3 in a sealing manner. The sealing section 9 thus prevents compressed gas from escaping along the traction cable 3 in the direction of the cable guide 6 and thus through the recess 5 into the environment. The guide member 7 also has an abutting portion 10 abutting an inner side of the tensioner tube 4 and protruding toward the piston 2 via the sealing portion 9.In the assembled state, the piston 2 bears against the bearing section 10 of the guide part 7, wherein a tubular section of the piston 2 directly surrounding the pull cable 3 is dimensioned such that its front end is spaced apart from the sealing section 9. By forming both a sealing section 9 and an abutment section 10, the function of sealing and providing a stop for the piston 2 is separated, whereby on the one hand a better seal for the traction cable 3 is provided and on the other hand a stop for the piston 2 is more accurately predefined.List of reference characters1 Gas generator 2 Piston 3 Traction cable 4 Tightening tube 5 Recess 6 Cable guide 7 Guide part 8 Fastening 9 Sealing section 10 Contact section

Claims

Tensioning device for a seat belt component, having - a gas generator (1) for generating a compressed gas, - a piston (2) which can be driven by the compressed gas, - a pull cable (3) which is connected to the piston (2) and can be connected to a seat belt component which is to be set into a tensioning movement, - a tensioning tube (4) for receiving and guiding the piston (2), - a guide part (7) for the pull cable (3) which is arranged at least in sections in the tensioning tube (4), wherein the guide part (7) sealingly surrounds the pull cable (3) on its side facing the piston (2) by means of a sealing section (9), wherein the piston (2) bears against the guide part (7) in an initial state, wherein the guide part (7) has an abutment portion (10) on its outer periphery facing an inner surface of the tensioner tube (4) and that the piston (2) abuts the abutment portion (10) in the initial state, characterized in that the abutment portion (10) protrudes in the axial direction beyond the sealing portion (9) in the direction of the piston (2).Tensioning device for a seat belt component, having - a gas generator (1) for generating a compressed gas, - a piston (2) which can be driven by the compressed gas, - a pull cable (3) which is connected to the piston (2) and can be connected to a seat belt component which is to be set into a tensioning movement, - a tensioning tube (4) for receiving and guiding the piston (2), - a guide part (7) for the pull cable (3) which is arranged at least in sections in the tensioning tube (4), wherein the guide part (7) sealingly surrounds the pull cable (3) on its side facing the piston (2) by means of a sealing section (9), wherein the piston (2) bears against the guide part (7) in an initial state, wherein the guide part (7) has an abutment portion (10) on its outer periphery facing an inner surface of the tensioner tube (4) and that the piston (2) in the initial state abuts the abutment portion (10), characterized in that the sealing portion (9) in the initial state is spaced apart in the axial direction from a portion of the piston (2) directly surrounding the traction cable (3).Tensioning device according to one of the preceding claims, wherein the bearing section (10) of the guide part (7) bears against the inner surface of the tensioning tube (4) in the initial state.Tensioning device according to one of the preceding claims, wherein the tensioning tube (4) has a recess (5) in its jacket between the gas generator (1) and the piston (2), and wherein the tensioning device comprises a cable guide (6) which projects through the recess (5) into the tensioning tube (4) and with which the traction cable (3) is led out of the tensioning tube (4) through the recess (5).The tightening device according to claim 4, wherein the cable guide (6) engages the guide part (7).The tightening device according to claim 4 or 5, wherein the guide part (7) has a receptacle and wherein the gas generator (1) is arranged in the receptacle.Tensioning device according to one of Claims 4 to 6, wherein the recess (5) is arranged in a portion of the tensioning tube (4) which is of rectilinear design.Tensioning device according to one of the preceding claims, wherein the tensioning tube (4) is formed in a straight line over its entire extent.

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