Belt tightener

Abstract

The invention relates to a belt tensioner (30) for a vehicle occupant restraint system comprising a housing (32), a working chamber (34) into which the compressed gas released in the case of restraint is flowing, a pull rope (24) extending through an opening (36) within the housing (32) and a sealing bush (10) for sealing the working chamber (34) against the opening (36) between the pull rope (24) and the housing (32), with the sealing bush (10) comprising a sleeve (16) and a sealing element (12) and the sealing bush (10) being pressed onto the pull rope (24) by plastic deforming of the outer sleeve (16).

Claims

1. A belt tensioner (30) for a vehicle occupant restraint system comprising a housing (32), a working chamber (34) into which compressed gas released in a case of restraint is flowing, a pull rope (24) extending through an opening (36) within the housing (32) and a sealing bush (10) for sealing the working chamber (34) against the opening (36) between the pull rope (24) and the housing (32), wherein the sealing bush (10) comprises an outer sleeve (16) and an inner sealing element (12), with the sealing bush (10) being pressed onto the pull rope (24) by plastic deforming of the outer sleeve (16), and wherein the sealing bush (10) is maintained in a fixed position within the housing (32) by contacting a shoulder of the housing on one side of the sealing bush (10).

2. The belt tensioner according to claim 1, wherein the sleeve (16) is made from steel.

3. The belt tensioner according to claim 1, wherein an axial length of the inner sealing element (12) is at least equal to that of the sleeve (16).

4. The belt tensioner according to claim 1, wherein the inner sealing element (12) in a non-deformed state has an inner diameter (d.sub.I) which is at least as large as a largest diameter (d.sub.S) of the pull rope (24).

5. The belt tensioner according to claim 1, wherein the inner sealing element (12) includes at least one radially outer sealing lip (18) which serves for sealing the working chamber (34) in a radial direction of the pull rope (24) and in an axial direction projects from the sleeve (16), and has an outer diameter which is at least as large as an outer diameter (d.sub.A) of the sleeve (16) in a non-deformed state.

6. The belt tensioner according to claim 1, wherein the inner sealing element (12) includes at least one axial sealing lip (20) which serves for sealing the working chamber (34) in an axial direction of the pull rope (24) and projects from the sleeve (16) in the axial direction.

7. The belt tensioner according to claim 6, wherein at least one radially outer sealing lip (18) and the axial sealing lip (20) are arranged on opposite axial ends of the sealing bush (10), the at least one radially outer sealing lip (18) for sealing the working chamber (34) in a radial direction of the pull rope (24), the at least one radially outer sealing lip (18) projecting from the sleeve (16) in the axial direction, the at least one radially outer sealing lip (18) having an outer diameter which is at least as large as an outer diameter (d.sub.A) of the sleeve (16) in a non-deformed state.

8. The belt tensioner according to claim 1, wherein the inner sealing element (12) includes at least one cable sealing lip (22) whose inner diameter is smaller than an inner diameter (d.sub.I) of the inner sealing element (12) distant from the cable sealing lip (22) in a non-deformed state.

9. The belt tensioner according to claim 8, wherein the cable sealing lip (22) is disposed at an axial end of the inner sealing element (12).

10. The belt tensioner according to claim 1, wherein the pull rope (24) is a steel rope.

11. The belt tensioner according to claim 9, wherein the inner sealing element (12) includes at least one radially outer sealing lip (18) which serves for sealing the working chamber (34) in a radial direction of the pull rope (24) and in an axial direction projects from the sleeve (16), the at least one radially outer sealing lip (18) having an outer diameter which is at least as large as an outer diameter (d.sub.A) of the sleeve (16) in the non-deformed state, the at least one radially outer sealing lip (18) being disposed at the same axial end of the inner sealing element (12) as the cable sealing lip (22).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and features will be evident from the following description in connection with the enclosed drawings, wherein:

(2) FIG. 1 shows in a sectional view a sealing bush for a belt tensioner according to the invention;

(3) FIG. 2 shows in a sectional view a sealing bush for a belt tensioner according to the invention which is arranged on a pull rope; and

(4) FIG. 3 shows in a sectional view a belt tensioner according to the invention comprising a housing and a sealing bush according to FIG. 1 pressed onto the pull rope.

DESCRIPTION

(5) FIG. 1 shows a cylindrical multi-part sealing bush 10 which includes a radially inner circular-cylindrical sealing element 12 having an axial through-hole 14 surrounded at its radially outer circular-cylindrical cover surface by a sleeve 16 made from steel.

(6) The sealing element 12 is longer in the axial direction than the sleeve 16 so that the sealing element 12 includes an axial projection on both sides of the sleeve 16.

(7) The sealing element 12 is made from elastomer or a metal which is softer as compared to steel.

(8) At an axial end of the sealing bush 10 the sealing element 12 includes a radially outer sealing lip 18 in the form of a collar projecting in the axial direction from the sleeve 16 and having an outer diameter which is at least as large as the outer diameter d.sub.A of the sleeve 16 and preferably larger than d.sub.A.

(9) On the side opposed to the end including the sealing lip 18, the sealing element 12 has an axial sealing lip 20 which is formed by the portion projecting from the sleeve 16 in the axial direction.

(10) At the axial end where the radially outer sealing lip 18 is provided, the sealing element 12 includes a cable sealing lip 22 which protrudes radially inwardly into the axial through-hole 14 and whose diameter is smaller than the inner diameter d.sub.I of the sealing element 12 distant from the cable sealing lip 22.

(11) The sealing bush 10 may be manufactured as two-component part for example by injection-molding or may consist of two separate elements as a subassembly.

(12) FIG. 2 illustrates the sealing bush 10 fastened on the pull rope 24 in the form of a steel rope in this case.

(13) In order to fasten the sealing bush 10 on the pull rope 24, the pull rope 24 is threaded through the through-hole 14, with the inner diameter d.sub.I of the sealing element 12 being at least as large as the largest diameter d.sub.S of the pull rope 24.

(14) Alter having positioned the sealing hush 10, the sleeve 16 disposed externally around the sealing element 21 is plastically deformed by a force F. This permanent reforming of the sleeve 16 helps pressing the softer more elastic sealing element 12 against the pull rope 24 which is not smooth at the outer periphery and thus the sealing bush 10 is fastened on the pull rope 24. The sealing element 12 is pressed into recesses at the outer periphery of the pull rope 24.

(15) In FIG. 3, a belt tensioner 30 for a vehicle occupant restraint system is shown which is fastened on the pull rope 24 via the sealing bush 10. The belt tensioner 30 comprises a housing 32, a working chamber 34 into which the released compressed gas is flowing in the case of restraint and is acting on the sealing bush 10 by a pressure p, as well as an opening 36 through which the pull rope 24 is guided out of the housing 32. The pull rope is moved to the left in the case of restraint according to FIG. 3. The sealing bush is maintained in position within the housing 32 by contacting the shoulder shown in FIG. 3 on the right-hand side of the sealing bush.

(16) The sealing bush 10 serves not only for fastening but also for sealing the working chamber 34 against the opening 36 between the pull rope 24 and the housing 32.

(17) 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.

(18) In the radial direction, the opening 36 is sealed by the radial sealing lip 18 of the sealing bush 10.

(19) The safe position of the sealing bush 10 within the housing 32 may be secured via the system pressure and an appropriate contact surface of the sealing bush 10 on the housing 32.

(20) Alternatively, the sealing bush 10 may also be additionally secured via clamping elements and/or gluing procedures.