Belt penalty

Abstract

Belt retractor (10) for a safety belt system, with a belt retractor frame (12) in which a belt reel (14) is accommodated, and with a belt tensioner (11) which has a tensioner tube (20) and a force transmission element (22) which is guided in the tensioner tube (20), as well as a gas generator (18) which provides compressed gas for displacing the force transmission element (22) in the tensioner tube (20), wherein the tensioner tube (20) has a fixed connection (28) to the belt retractor frame (12) and the fixed connection (28) is a welded connection, wherein the belt tensioner (11) comprises a cover (16) which covers one end of an axis of the belt reel (14) and which is welded to the belt retractor frame (12), the fixed connection being formed between the tensioner tube (20) and the cover (16), characterized in that the cover (16) has a bent edge (40) which rests on a flat edge (38) of the belt retractor frame (12), the welded connection running on the bent edge (40), and that a fastening section (30) is provided on the tensioner tube (20), which has a bent fixing tab (32) which is inserted into a recess (36) of the belt retractor frame (12) and which is welded to the cover (16).

Description

[0001] The invention relates to a pyrotechnically driven belt tensioner for a safety belt system.

[0002] A belt pretensioner is designed to reduce certain factors that could negatively impact the restraint of a vehicle occupant in a restraint situation, before the vehicle occupant is displaced forward and, if necessary, a force limiting device is activated. These factors include the so-called slack-in effect (belt webbing wound loosely onto the belt reel) and slack-in effect (belt webbing lying loosely against the vehicle occupant). The belt pretensioner reduces slack and the slack-in effect within a very short time, for example, by winding belt webbing onto a belt reel of a belt retractor, thereby tightening the belt webbing. This allows the vehicle occupant to participate in the vehicle's deceleration at an early stage. It also improves the conditions for the subsequent deployment of a force limiting device.

[0003] Nowadays, pyrotechnically driven belt tensioners are commonly used to provide the high forces required for belt tensioning in a sufficiently short time.

[0004] A known design of a belt pretensioner features a force transmission element that is displaced within a pretensioner tube by the gas pressure generated by the gas generator when the belt pretensioner is activated. The force transmission element interacts with the belt reel, causing it to rotate to tighten the belt.

[0005] From the generic DE 101 19 199 A1, a belt retractor for a safety belt system is known, comprising a belt retractor frame in which a belt spool is accommodated, and a belt tensioner comprising a tensioner tube and a force transmission element guided in the tensioner tube. Furthermore, a gas generator is provided, which provides compressed gas for displacing the force transmission element in the tensioner tube. The tensioner tube has a fixed connection to the belt retractor frame, and the fixed connection is a welded connection. A cover covers one end of an axle of the belt spool and is welded to the belt retractor frame, the fixed connection being formed between the tensioner tube and the cover.

[0006] DE 10 2014 006 500 A1 describes a belt tensioner in which a T-shaped end of the tensioner tube is positively attached to a frame.

[0007] From DE 10 2012 023 031 A1 it is also known to create welded joints on belt tensioners by laser welding

[0008] To reduce noise during normal driving, a permanent, secure connection between the tensioner tube and the belt retractor to which the belt tensioner is connected is desirable. Achieving this is the object of the invention.

[0009] To achieve this object, the invention provides the characterizing features of claim 1. A belt retractor for a safety belt system, comprising a belt retractor frame in which a belt spool is accommodated, also includes a belt tensioner having a tensioner tube and a force transmission element guided in the tensioner tube, as well as a gas generator that provides compressed gas for displacing the force transmission element in the tensioner tube. The tensioner tube has a fixed connection to the tensioner housing and / or belt retractor frame, wherein the fixed connection is a welded connection. The welded connection eliminates the play between the tensioner tube and the tensioner housing and / or the belt retractor frame, thereby reducing unwanted noise.In addition, the number of required components can be reduced because the welded connection can be selected in such a way that the tensioner tube is securely fixed to the belt retractor frame even without additional supporting components.

[0010] The generic belt pretensioner comprises a cover that covers one end of a belt spool spindle and is welded to the belt retractor frame. The permanent welded connection is formed between the pretensioner tube and the cover, i.e., the pretensioner tube is welded to the cover. In particular, only a single welding process is required to attach both the cover and the pretensioner tube to the belt retractor frame. The cover is welded to the belt retractor frame and the pretensioner tube to the cover simultaneously. A direct welded connection between the pretensioner tube and the belt retractor frame is not required.

[0011] The cover usually covers the belt retractor on the pretensioner side. It often also includes a bearing for one end of the belt spool's spindle.

[0012] According to the invention, the cover has a bent edge that rests on a flat edge of the belt retractor frame, with the welded joint running along the bent edge. The flat edges of the belt retractor frame and the cover allow the cover and the belt retractor frame to be easily and securely connected to each other.

[0013] In order to easily weld the tensioner tube to the cover at the same time, the invention provides a fastening section on the tensioner tube which has a bent fixing tab which is inserted into a recess in the belt retractor frame and which is welded to the cover. The top side of the fixing tab is, for example, at the same level as the flat edge of the belt retractor frame, so that the cover rests on the flat edge of the belt retractor frame without any height differences and on the fixing tab in the area of the recess. A weld seam can then be drawn continuously over the bent edge of the cover, with the fixing tab being welded to the cover in the area of the recess instead of the flat edge of the belt retractor frame. This results in a secure connection between the cover, tensioner tube and housing frame, without the need for an additional welded connection between the tensioner tube and the belt retractor frame.

[0014] Preferably, the fixing tab fits precisely into the recess.

[0015] The recess may be a circumferentially closed opening in the edge of the belt retractor frame.

[0016] To simplify manufacturing, increase strength and minimize noise, the fastening section is preferably formed integrally with the rest of the tensioner tube.

[0017] The fastening section is advantageously arranged at an open outlet end of the tensioner tube, through which the force transmission element exits the tensioner tube. For example, an edge of the open outlet end can be formed into the fastening section including the fixing tab.

[0018] The fastening section can also have a wall section that extends as an extension of a tubular section of the tensioner tube. This wall section then extends a radially outer wall of the actual tensioner tube and forms a guide for the force transmission element emerging from the tensioner tube, which transfers kinetic energy to the belt reel in this area to cause it to rotate. The wall section can also serve to prevent the force transmission element from deflecting radially outward.

[0019] The welded joint is preferably made by laser welding.

[0020] In one possible embodiment, the belt tensioner has a drive wheel, and the force transmission element exiting the tensioner tube causes the drive wheel to rotate. In the area of the open exit end of the tensioner tube, the force transmission element then interacts with the drive wheel and transfers its kinetic energy to the drive wheel and thus to the belt reel coupled to the drive wheel.

[0021] The cover usually covers the drive wheel and can also form a guide for the power transmission element in the area where it exits the tensioner tube.

[0022] The force transmission element can be formed as a single piece or consist of several separate parts, for example, a series of balls, which can also be coupled together if necessary. The functional principle of the belt tensioner and the advantage of an intermediate element positively coupled to the stop element are the same in all cases.

[0023] When using a one-piece force transmission element, this can, for example, be an elongated, flexible, elastic and / or plastically deformable plastic component.

[0024] The invention is described in more detail below using an exemplary embodiment with reference to the accompanying drawings. In the drawings: - Fig. 1 a schematic perspective view of a belt retractor according to the invention in the fully assembled state; - Fig. 2 a schematic perspective view of the end of a tensioner tube of the belt retractor according to the invention with a fastening section for connection to a belt retractor frame; - Fig. 3 a schematic perspective view of a welded connection between the belt retractor frame, a cover of a belt tensioner and the tensioner tube; - Fig. 4 a schematic perspective view of a section of the belt retractor according to the invention with mounted tensioner tube; - Fig. 5 a schematic sectional view of the connection point of the tensioner tube, cover and belt retractor frame of the belt retractor according to the invention, - Fig. 6 a schematic perspective view of the fully assembled belt tensioner, with the cover omitted for illustrative purposes; and - Fig. 7 and Fig. 8 schematic perspective views of the fully assembled belt retractor according to the invention from different sides.

[0025] The figures show the essential parts of a belt retractor 10 with a pyrotechnically driven belt tensioner 11 integrated therein. A belt reel 14 is rotatably mounted in a belt retractor frame 12 of the belt retractor 10, onto which the belt webbing can be wound or removed (not shown here). At one end of the axis of the belt reel 14, in Fig. 1 at the left-hand end, a drive wheel 15 is provided (indicated by dashed lines in Fig. 1), which is arranged concentrically with the axis of the belt reel 14 and which is Fig. 1 is covered by a cover 16 of the belt tensioner 11. The drive wheel 15 has external teeth and serves to rotate the belt spool 14 via the belt tensioner 11.

[0026] The belt tensioner 11 has a gas generator 18, which is arranged at one end of a tensioner tube 20, so that generated compressed gas can flow into the tensioner tube 20. A force transmission element 22 is slidably arranged in the tensioner tube 20 (see Fig. 1).

[0027] The direction of movement of the force transmission element 22 is determined first by the shape of the tensioner tube 20 and then by a guide (not shown in detail) in the cover 16 of the belt tensioner 11. The tensioner tube 20 is partially strongly curved in several spatial directions, so that the direction of movement of the force transmission element 22 is not linear.

[0028] The force transmission element 22 is accelerated by the gas generated by the gas generator 18, leaves the tensioner tube 20 through an open outlet end 24 of the tensioner tube 20, and interacts with the drive wheel 15 in an engagement region 26, so that the drive wheel 15 is set in rotation by the force transmission element 22 being pushed past. The engagement region 26 is located directly at the open outlet end 24 of the tensioner tube 20, so that the force transmission element 22 impacts the drive wheel 15 with the highest possible kinetic energy (see Fig. 4).

[0029] The power transmission element 22 here is an elongated component made entirely of a plastic material that is flexible enough to follow the curvature of the tensioner tube 20 and is preferably plastically deformable enough for the drive wheel 15 to press into the power transmission element 22 and thus create an engagement structure that contributes to establishing good power transmission between the power transmission element 22 and the drive wheel 15 while the power transmission element 22 is pushed past the drive wheel 15.

[0030] The belt tensioner 11 also has a force limiting device, which is not shown in detail here and which allows the belt webbing to be pulled out again after the belt has been tensioned.

[0031] The tensioner tube 20 has a fixed connection 28 to the belt retractor 10 and to the belt tensioner 11. In this example, the fixed connection 28 is a welded connection that connects the tensioner tube 20, the cover 16 and the belt retractor frame 12 and fixes them together without play.

[0032] At the open outlet end 24 of the tensioner tube 20, a fastening section 30 is formed, into which the open outlet end 24 merges in one piece (see for example Fig. 2).

[0033] The fastening section 30 has a bent fixing tab 32 which is aligned approximately perpendicular to the body of the tensioner tube 20 in the region of the open outlet end 24, and a wall section 34 which is approximately perpendicular to the fixing tab 32 and which extends approximately in extension of an outer wall of the body of the tensioner tube 20.

[0034] In the area of the open outlet end 24, the tensioner tube 20, together with the fastening section 30, is shaped such that it radially outwards delimits a guide channel for the force transmission element 22 formed between the engagement area 26 of the drive wheel 15 and the tensioner tube 20 and thereby prevents the force transmission element 22 from escaping from contact with the drive wheel 15.

[0035] To secure the tensioner tube 20, the fixing tab 32 is inserted into a recess 36 in a flat edge 38 of the belt retractor frame 12. In this example, the recess 36 is closed to the outside, so that the flat edge 38 runs uninterrupted along an outer edge of the belt retractor frame 12.

[0036] In this embodiment, the cover 16 has a bent edge 40 (indicated in Fig. 3 and clearly visible in the Fig. 4 and Fig. 5). The bent edge 40 of the cover 16 is placed on the flat edge 38 of the belt retractor frame 12 in such a way that these sections lie flat against each other, as shown in the Fig. Show 3 to 5.

[0037] The fixing tab 32 is inserted into the recess 36 in such a way that the fixing tab 32 runs at the same height as the edge 38 of the belt retractor frame 12 and, as a result, the edge 40 of the cover 16 rests on the fixing tab 32 in the area of the fixing tab 32 without any difference in height, while the edge 40 of the cover 16 to the right and left of the fixing tab 32 lies flat on the edge 38 of the belt retractor frame 12.

[0038] The belt retractor frame 12, the cover 16, and the tensioner tube 20 can thus be welded together in a single operation and, if necessary, using a single weld seam 42. Away from the fixing tab 32, the weld seam 42 directly connects the cover 16 to the belt retractor frame 12. In the area of the fixing tab 32, however, only the cover 16 and the fixing tab 32 are welded together by the weld seam 42, which forms the connection 28 in this section. The tensioner tube 20 is not welded directly to the belt retractor frame 12 here. However, since the fixing tab 32 only extends over a relatively short section and the connection 28 is short compared to the entire weld seam 42, a firm and play-free connection between the tensioner tube 20 and the belt retractor frame 12 is nevertheless created.

[0039] In this example, laser welding is used as the welding process.

[0040] The weld seam 42 may be interrupted in sections, as shown in the Fig. 6 to 8, is preferably manufactured in a single operation.

[0041] On the wall section 34 of the fastening section 30, a projection 44 is formed which engages in a recess 46 in the cover 16, so that the position of the tensioner tube 20 with respect to the belt retractor frame 12 is determined during pre-assembly and during the welding process.

Claims

[1] Belt retractor (10) for a safety belt system, with a belt retractor frame (12) in which a belt reel (14) is accommodated, and with a belt tensioner (11) which has a tensioner tube (20) and a force transmission element (22) which is guided in the tensioner tube (20), as well as a gas generator (18) which provides compressed gas for displacing the force transmission element (22) in the tensioner tube (20), wherein the tensioner tube (20) has a fixed connection (28) to the belt retractor frame (12) and the fixed connection (28) is a welded connection, wherein the belt tensioner (11) comprises a cover (16) which covers one end of an axis of the belt reel (14) and which is welded to the belt retractor frame (12), the fixed connection being formed between the tensioner tube (20) and the cover (16), characterized bythat the cover (16) has a bent edge (40) which rests on a flat edge (38) of the belt retractor frame (12), the welded connection running on the bent edge (40), and that a fastening section (30) is provided on the tensioner tube (20), which has a bent fixing tab (32) which is inserted into a recess (36) of the belt retractor frame (12) and which is welded to the cover (16). [2] Belt retractor according to claim 1, characterized by that the fastening section (30) is formed integrally with the remaining tensioner tube (20). [3] Belt retractor according to one of claims 1 or 2, characterized by that the fastening section (30) is arranged at an open outlet end (24) of the tensioner tube (20), through which the force transmission element (22) leaves the tensioner tube (20). [4] Belt retractor according to one of the preceding claims, characterized bythat the fastening section (30) has a wall section (34) which extends in extension of a tubular section of the tensioner tube (20). [5] Belt retractor according to one of the preceding claims, characterized by that the welded joint is made by laser welding. [6] Belt retractor according to one of the preceding claims, characterized by that the belt tensioner (11) has a drive wheel (15), and the force transmission element (22) emerging from the tensioner tube (20) sets the drive wheel (15) in rotation. [7] Belt retractor according to one of the preceding claims, characterized by that the force transmission element (22) is an elongated, flexible, elastically and / or plastically deformable plastic component.

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