Belt penalty

Abstract

Belt tensioner (30) for a vehicle occupant restraint system with a housing (32), a working chamber (34) into which the compressed gas released in the event of restraint flows, a traction cable (24) which extends through an opening (36) in the housing (32), and a sealing bushing (10) for sealing the working chamber (34) with respect to the opening (36) between the traction cable (24) and the housing (32), characterized in that the sealing bushing (10) is cylindrical and comprises an outer sleeve (16) and an inner sealing element (12), wherein the radially outer circular-cylindrical surface of the inner sealing element (12) is surrounded by the sleeve (16), and wherein the sealing bushing (10) is pressed onto the traction cable (24) by plastic deformation of the outer sleeve (16).

Description

[0001] The invention relates to a belt tensioner for a vehicle occupant restraint system with a housing, a working chamber into which the compressed gas released in the event of restraint flows, a pull cable which extends through an opening in the housing, and a sealing bushing for sealing the working chamber against the opening between the pull cable and the housing.

[0002] Belt tensioners with a pull cable as the tension transmission mechanism are well known. The high requirements for tightness between the pull cable and the housing, to ensure reliable function in the event of a restraint, can only be met by sheathing the pull cable or using a sleeve system.

[0003] When sealing the traction cable directly with a soft sealing element, it is almost impossible to reconcile the dimensions of the sealing element optimized for installation with the dimensions required for high sealing requirements. On the other hand, sealing elements with the necessary diameters for good sealing during the threading process are only possible with considerable effort.

[0004] The generic DE 296 09 054 U1 describes a belt tensioner for a vehicle occupant restraint system with a housing, a working chamber into which the compressed gas released in the event of restraint flows, a pull cable which extends through an opening in the housing, and with a sealing bush for sealing the working chamber against the opening between the pull cable and the housing.

[0005] Another belt tensioner with a sealing element surrounding the traction cable is known from DE 297 08 880 U1.

[0006] The document DE 10 2013 007 912 A1 further describes a belt tensioner in which the sealing element interacting with the traction cable has a cable sealing lip arranged at an axial end of the sealing element, the inner diameter of which is smaller than the inner diameter of the sealing element.

[0007] The object of the invention is to provide a belt tensioner with a pull rope which has a sealing system which meets high sealing requirements and at the same time is easy to install.

[0008] To achieve the object, a belt tensioner for a vehicle occupant restraint system is provided, comprising a housing, a working chamber into which the compressed gas released in the event of restraint flows, a tension cable which extends through an opening in the housing, and a sealing bushing for sealing the working chamber from the opening between the tension cable and the housing, wherein the sealing bushing is cylindrical and comprises an external sleeve and an internal sealing element, wherein the radially outer circular cylindrical surface of the internal sealing element is surrounded by the sleeve, and wherein the sealing bushing is pressed onto the tension cable by plastic deformation of the external sleeve. In the undeformed state, i.e. in its delivered state, the sealing bushing has dimensions which enable easy installation, for example by threading, on the tension cable.After this process, the outer sleeve of the sealing bushing is plastically deformed to achieve the necessary seal between the tension cable and the sealing bushing. This plastic deformation can be achieved, in particular, by crimping or pressing with a tool such as pliers or a press. After the forming process, the outer dimensions of the sealing bushing correspond to the required installation dimensions of the housing, so that the sealing bushing can now be inserted into the housing. In this way, the belt tensioner housing can be quickly mounted on the tension cable in just a few simple steps, ensuring a high level of tightness.

[0009] Preferably, the sleeve is made of steel, which has advantageous deformation properties and, in particular, can apply a high force to the sealing element, which is softer than the sleeve, in order to ensure a high level of tightness and a secure fit.

[0010] The sealing element can be made of an elastomer or soft metal.

[0011] According to a preferred embodiment, the sealing element is axially at least as long as the sleeve. As a result, the sealing element has an axial projection on the sleeve, preferably of a few millimeters, which can rest against the housing and act as a sealing element there.

[0012] It is advantageous if the sealing element, in its undeformed state, has an inner diameter that is at least as large as the largest diameter of the traction cable. This allows for easy installation of the sealing bushing with the sealing element, as frictional resistance is reduced, for example, when threading the cable.

[0013] The sealing element preferably has at least one radially outer sealing lip, which serves to seal the working chamber in the radial direction of the traction cable and protrudes axially beyond the sleeve. The outer diameter of the sealing element is at least as large as the outer diameter of the sleeve in the undeformed state. This provides the sealing bush with a sealing section on the sealing element, which seals the opening around the traction cable in the radial direction toward the housing, thus increasing the tightness.

[0014] Preferably, the sealing element has at least one axial sealing lip, which serves to seal the working chamber in the axial direction of the traction cable and protrudes axially beyond the sleeve. This type of seal is particularly advantageous because, in the event of a retention event, the sealing element is pressed against the housing by the high pressure in the working chamber, thus resulting in improved sealing.

[0015] According to a preferred embodiment, the outer radial sealing lip and the axial sealing lip are arranged at opposite ends of the sealing bushing. In this way, deformation of one sealing lip in the event of a restraint does not impair the function of the other sealing lip, and the sealing bushing has two independent sealing lips, which increase the sealing and thus the functional reliability of the belt tensioner.

[0016] According to a further preferred embodiment, the sealing element has at least one cable sealing lip, the inner diameter of which is smaller than the inner diameter of the sealing element remote from the cable sealing lip in the undeformed state. The sealing lip thus protrudes radially inward and presses against the traction cable. The cable sealing lip, which thus protrudes into the through-opening of the sealing element, prevents the sealing bushing from slipping during assembly after it has been pushed onto the traction cable and before it is deformed. This prevents the sealing bushing from becoming lost and enables more precise positioning of the sealing bushing on the traction cable.

[0017] The cable sealing lip can be arranged at an axial end of the sealing element, in particular at the end with the outer radial sealing lip, in order to enable easier production and quality assurance of the sealing element.

[0018] It is advantageous if the traction cable is made of steel. This ensures that the function of the traction cable is not impaired by the high temperatures and forces acting during the restraint event.

[0019] Further advantages and features are evident from the following description in conjunction with the attached drawings. These show: - Fig. 1 shows a sectional view of a sealing bush for a belt tensioner according to the invention; - Fig. 2 shows a sectional view of a sealing bushing for a belt tensioner according to the invention, which is arranged on a traction cable; and - Fig. 3 in a sectional view of a belt tensioner according to the invention with a housing and a sealing bush according to Fig. 1, which is crimped onto the traction cable.

[0020] In Fig. 1 shows a cylindrical, multi-part sealing bush 10 which has a radially inner, circular-cylindrical sealing element 12 with an axial through-opening 14, which is surrounded on its radially outer circular-cylindrical surface by a sleeve 16 made of steel.

[0021] The sealing element 12 is longer in the axial direction than the sleeve 16, so that the sealing element 12 has an axial projection on both sides of the sleeve 16.

[0022] The sealing element 12 is made of an elastomer or a metal that is softer than steel.

[0023] At one axial end of the sealing bushing 10, the sealing element 12 has a radially outer sealing lip 18 in the form of a collar, which projects in the axial direction relative to the sleeve 16 and has an outer diameter which is at least as large as the outer diameter d A the sleeve 16, preferably larger than d A is.

[0024] On the side opposite the end with the sealing lip 18, the sealing element 12 has an axial sealing lip 20, which is formed by the section projecting in the axial direction relative to the sleeve 16.

[0025] The sealing element 12 has at the axial end, at which the radially outer sealing lip 18 is located, a cable sealing lip 22 which projects into the axial through-opening 14, ie radially inward, and whose diameter is smaller than the inner diameter d I of the sealing element 12 away from the cable sealing lip 22.

[0026] The sealing bushing 10 can be manufactured as a two-component part, for example by overmolding, or as a pre-assembled assembly consisting of two separate elements.

[0027] Fig. 2 shows the sealing bushing 10, which is fastened to the traction cable 24, which is designed here as a steel cable.

[0028] In order to fix the sealing bushing 10 on the traction cable 24, the traction cable 24 is threaded through the through-hole 14, whereby the inner diameter d I of the sealing element 12 is at least as large as the largest diameter d S of the pull rope 24.

[0029] After the sealing bushing 10 has been positioned, the sleeve 16 arranged outside the sealing element 12 is plastically deformed by a force F. This permanent deformation of the sleeve 16 presses the softer, more elastic sealing element 12 against the traction cable 24, which is not smooth on its outer circumference, thus securing the sealing bushing 10 to the traction cable 24. The sealing element 12 is pressed into recesses on the outer circumference of the traction cable 24.

[0030] In Fig. 3 shows a belt tensioner 30 for a vehicle occupant restraint system, which is attached to the tension cable 24 via the sealing bushing 10. The belt tensioner 30 comprises a housing 32, a working chamber 34, into which the released compressed gas flows in the restraint case and acts with a pressure p on the sealing bushing 10, as well as an opening 36 through which the tension cable 24 is guided out of the housing 32. The tension cable is guided in the restraint case according to Fig. 3 to the left. The sealing bush is thereby secured by contact with the Fig. 3 on the right side of the sealing bushing is held in position in the housing 32.

[0031] The sealing bushing 10 serves not only for fastening, but also for sealing the working space 34 against the opening 36 between the pull cable 24 and the housing 32.

[0032] In the axial direction, the axial sealing lip 20 of the sealing bush 10 seals the working chamber 34 against the wall of the guide 40 of the housing 32 delimiting the opening 36.

[0033] In the radial direction, the opening 36 is sealed by the radial sealing lip 18 of the sealing bush 10.

[0034] The secure position of the sealing bushing 10 in the housing 32 can be secured via the system pressure and a corresponding contact surface of the sealing bushing 10 on the housing 32.

[0035] Alternatively, the sealing bushing 10 can also be additionally secured using clamping elements and / or adhesive processes.

Claims

[1] Belt tensioner (30) for a vehicle occupant restraint system with a housing (32), a working chamber (34) into which the compressed gas released in the restraint case flows, a traction cable (24) which extends through an opening (36) in the housing (32), and a sealing bush (10) for sealing the working chamber (34) with respect to the opening (36) between the traction cable (24) and the housing (32), characterized by in that the sealing bushing (10) is cylindrical and comprises an outer sleeve (16) and an inner sealing element (12), wherein the radially outer circular cylindrical surface of the inner sealing element (12) is surrounded by the sleeve (16), and wherein the sealing bushing (10) is pressed onto the traction cable (24) by plastic deformation of the outer sleeve (16). [2] Belt tensioner according to claim 1, characterized by that the sleeve (16) is made of steel. [3] Belt tensioner according to one of the preceding claims, characterized bythat the sealing element (12) is axially at least as long as the sleeve (16). [4] Belt tensioner according to one of the preceding claims, characterized by that the sealing element (12) in the non-deformed state has an inner diameter d I which is at least as large as the largest diameter d S of the pull rope (24). [5] Belt tensioner according to one of the preceding claims, characterized by that the sealing element (12) has at least one radially outer sealing lip (18) which serves to seal the working space (34) in the radial direction of the traction cable (24) and protrudes in the axial direction beyond the sleeve (16), and has an outer diameter which is at least as large as the outer diameter d A the sleeve (16) in the undeformed state. [6] Belt tensioner according to one of the preceding claims, characterized bythat the sealing element (12) has at least one axial sealing lip (20) which serves to seal the working space (34) in the axial direction of the traction cable (24) and protrudes in the axial direction beyond the sleeve (16). [7] Belt tensioner according to claims 5 and 6, characterized by that the outer radial sealing lip (18) and the axial sealing lip (20) are arranged on opposite axial ends of the sealing bush (10). [8] Belt tensioner according to one of the preceding claims, characterized by that the sealing element (12) has at least one cable sealing lip (22) whose inner diameter is smaller than the inner diameter d I of the sealing element (12) away from the cable sealing lip (22) in the non-deformed state. [9] Belt tensioner according to claims 5 and 8, characterized by that the cable sealing lip (22) is arranged at an axial end of the sealing element (12). [10] Belt tensioner according to one of the preceding claims, characterized bythat the traction cable (24) is a steel cable.

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