Belt penalty

Abstract

A belt retractor (10) of a safety belt system has a belt tensioner (11) which can rotate a belt spool (14) of the belt retractor (10) which is accommodated in a belt retractor frame (12). The belt retractor frame (12) is closed on the tensioner side in the region of the axis of the belt spool (14) with a cover (16) and a bearing for the belt spool (14) is provided in the cover (16). The cover (16) has a first, pot-shaped cover part (16a) which is fastened directly to the belt retractor frame (12) and which has a side wall (24) which merges into a flat section (26). An opening (32) is provided in the flat section (26), and a second cover part (16b) is provided which engages in the opening (32) in the first cover part (16a) and on which a bearing (40) is formed in which one end (42) of the axis of the belt reel (14) is mounted.

Description

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

[0002] A belt tensioner 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 deployed. These factors include the so-called film spool effect (belt webbing wound loosely onto the belt spool) and belt slack (belt webbing lying loosely on the vehicle occupant). The belt tensioner reduces belt slack and the film spool effect within a very short time, for example, by winding belt webbing onto a belt retractor's spool, thereby tightening the belt. 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 tensioner includes a force transmission element that is displaced in a tensioner tube by the gas pressure generated by the gas generator when the belt tensioner is activated. The force transmission element interacts with the belt spool, causing it to rotate to tighten the belt.

[0005] The belt tensioner is usually located on one side of the belt spool, from where the force transmission element interacts indirectly with the belt spool, causing it to rotate. The belt retractor frame is sealed from the environment on this side by a cover that covers one end of the belt spool's axis. To save space and reduce the number of components, a bearing for this end of the belt spool can be provided in the cover on the tensioner side.

[0006] For example, US 2016 / 0 244 021 A1 discloses a belt tensioner that is attached to the front end of a belt reel on the belt retractor frame. The axis of the belt reel is formed by a torsion bar with an extension that extends through a cover into the housing of the belt tensioner.

[0007] WO 2005 / 025 949 A1 shows a belt retractor with a belt tensioner mounted on the front side. A cover is arranged between the belt retractor frame and the belt tensioner, through which a projection extends the belt spool axis. This projection is provided with a toothing, via which the belt tensioner can rotate the belt spool for tightening.

[0008] The object of the invention is to further develop such a belt reel in such a way that a precise and trouble-free mounting of the belt reel axis on the cover is possible.

[0009] This object is achieved with a belt retractor having the features of claim 1. A belt retractor of a safety belt system has a belt tensioner which can set a belt spool of the belt retractor accommodated in a belt retractor frame into rotation, wherein the belt retractor frame is closed with a cover on the tensioner side in the region of the axis of the belt spool and a bearing for the belt spool is provided in the cover. The cover has a first pot-shaped cover part which is fastened directly to the belt retractor frame and which has a side wall which merges into a flat section. An opening is cut out in the flat section, and a second cover part is provided which engages in the opening in the first cover part and on which a bearing is formed in which one end of the axis of the belt spool is mounted.The second cover part preferably closes the belt retractor on the tensioner side to the outside, so that only the tolerances of a single component, namely the second cover part, are relevant for the bearing of the belt reel axis.

[0010] The position of the opening allows the second cover part and thus the bearing of the belt reel axis to be precisely positioned, which improves the central storage of the belt reel.

[0011] The second cover part is preferably designed to be resilient to a certain extent, which allows additional tolerances to be compensated.

[0012] A positioning structure can be provided on the second cover part, by means of which a radial position of the second cover part relative to the first cover part is defined. An axial position relative to the belt reel axis can also be specified by this positioning structure if necessary. Since the first cover part assumes a fixed position relative to the belt retractor frame, the position of the bearing in the second cover part relative to the belt reel is also precisely specified.

[0013] The positioning structure, for example, has at least one projection that rests against the inner edge of the opening in the first cover part. For assembly, the two cover parts simply need to be inserted into each other to complete the cover, while simultaneously correctly positioning the bearing of the belt reel axle.

[0014] Preferably, the projection is circumferentially encircling. However, it would also be conceivable to provide the projection only in sections along the circumference.

[0015] To improve positioning accuracy, the first cover part is advantageously made of a metal, particularly steel, and the second cover part is advantageously made of a plastic. The first cover part can be designed to withstand the high forces that occur during belt tensioning, while the second cover part has to bear less load and can therefore be manufactured from a plastic, for example, by injection molding. The spring action and compliance of the cover part perpendicular to the belt reel axis can also be specified within a narrow range.

[0016] Preferably, the bearing is formed centrally with respect to the positioning structure. The opening and the positioning structure can be circular. However, the circumference of the entire second cover part can have any shape.

[0017] The bearing, for example, is a ring-shaped projection into which the end of the belt reel axle is inserted.

[0018] For better support, the second cover part can extend radially in sections parallel to the flat section of the first cover part. In this embodiment, the second cover part is preferably inserted from the inside through the opening in the first cover part, so that the projection lying on the surface of the first cover part engages from the inside with the edge of the opening in the first cover part. The section of the second cover part extending radially beyond the projection then lies flat against the flat section of the first cover part, for example, so that no tilting forces can act on the second cover part.

[0019] The second cover part is attached to the first cover part in a suitable manner. This can be, for example, a simple plug-in connection maintained axially by preloading across the belt reel axis, or it can additionally be an adhesive connection, a clip or bayonet connection, or a welded connection.

[0020] The first cover part is preferably welded to the belt retractor frame, for example by laser welding, ensuring a strong and load-bearing connection. Since the second cover part rests on the first cover part, the belt reel bearing on the tensioner side is also firmly held to the belt retractor frame.

[0021] According to a preferred embodiment, the belt tensioner comprises a drive wheel arranged concentrically with the axis of the belt spool, and the force transmission element emerging from the tensioner tube sets the drive wheel in rotation. The drive wheel is connected to the belt spool, e.g., by being located directly on the axis of the belt spool, and rotates the belt spool at the same speed as that set by the force transmission element in order to wind up and tighten the belt webbing. The drive wheel is preferably housed under the cover.

[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; - Fig. 2 a schematic perspective view of the belt retractor from Fig. 1 seen from the tensioner side; - Fig. 3 a schematic sectional view of the belt retractor according to the invention; and - Fig. 4 an enlarged section of Fig. 3.

[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 belt webbing can be wound or removed (not shown here). On one side of the belt reel 14, in Fig. 1 on the left side, 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 10. 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 displaceably arranged in the tensioner tube 20 (see Fig. 1).

[0027] The force transmission element 22 is accelerated by the gas generated by the gas generator 18, exits the tensioner tube 20 through an open outlet end of the tensioner tube 20, and interacts with the drive wheel 15 in an engagement region, so that the drive wheel 15 is set in rotation by the force transmission element 22 being pushed past (not shown). The engagement region is located directly at the open outlet end of the tensioner tube 20, so that the force transmission element 22 impacts the drive wheel 15 with the highest possible kinetic energy.

[0028] 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 helps to ensure 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.

[0029] The belt tensioner 11 also has a force limiting device, which is not shown in detail here and which allows the belt to be pulled out again after the belt has been tensioned.

[0030] The direction of movement of the force transmission element 22 is initially determined by the shape of the tensioner tube 20 and subsequently 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.

[0031] The cover 16 is constructed in two parts. A first, pot-shaped cover part 16a has a partially cylindrical side wall 24 that transitions into a flat section 26. The exact shape of the side wall depends on the specific shape of the belt retractor frame 12 and the belt tensioner 11. The side wall 24 terminates at the end opposite the flat section 26 in a bent, flat edge 28. The cover 16 is firmly connected to the belt retractor frame 12 via the flat edge 28, in this case by welding superimposed sections of the flat edge 28 and a flat edge 30 of the belt retractor frame 12 together.

[0032] A circular opening 32 is cut out in the flat section 26 of the first cover part 16a.

[0033] A second cover part 16b engages into the opening 32, which is essentially disc-shaped and which covers the opening 32 from the inside of the first cover part 16a.

[0034] A positioning structure 34 is formed on the outer surface of the second cover part 16b, which defines the radial position of the second cover part 16b relative to the first cover part 16a. In this example, the positioning structure 34 is a circular projection 35 that fits snugly against the inner peripheral edge of the opening 32.

[0035] The second cover part 16b extends radially further outwards beyond the projection 35 into a contact section 36 (see Fig. 3 and Fig. 4), which lies flat against the inside of the flat section 26 of the first cover part 16a until it ends in a bent edge 38. In the area of ​​the opening 32, however, the cover 16 is formed only by the second cover part 16b, which closes off the belt retractor 10 from the environment in this area.

[0036] The bent edge 38 is spaced from the side wall 24 of the first cover part 16a, so that the second cover part 16b and the first cover part 16a are in contact with each other only via the projection 35 and the section 36.

[0037] The projection 35 and the opening 32 are designed such that the second cover part 16b rests against the first cover part 16a without play.

[0038] The outer circumference of the second cover part 16b does not have to be circular; its shape can be selected depending on the design of the belt retractor 10. However, the projection 35 preferably describes a circle, just like the opening 32.

[0039] At the center of the circle formed by the projection 35, a bearing 40 is formed for one end 42 of the axis of the belt reel 14. In this example, the bearing 40 has the shape of a circumferential annular projection into which the pin-shaped end 42 of the axis of the belt reel 14 is inserted. The end 42 of the axis of the belt reel 14 also has projections located radially outside the pin, which improve the retention of the end 42 in the bearing 40.

[0040] In this example, the first cover part 16a is made of steel, while the second cover part 16b is made of a suitable plastic. Due to its material properties and its flat, disc-like shape, the second cover part 16b has a certain flexibility along the axial direction of the belt spool 14. Therefore, the bearing 40 can hold the end 42 of the belt spool's axis with sufficient preload to compensate for tolerances without impeding the smooth rotation of the belt spool 14.

[0041] The second cover part 16b can be held on the first cover part 16a exclusively by the plug connection of the projection 35 in the opening 32 and the pretension exerted by the axis of the belt reel 14, but it is also possible to glue or weld the radially projecting section 36 to the inside of the flat section 26 of the first cover part 16a.

Claims

[1] Belt retractor (10) of a safety belt system, with a belt tensioner (11) which can set a belt reel (14) of the belt retractor (10) accommodated in a belt retractor frame (12) in rotation, wherein the belt retractor frame (12) is closed on the tensioner side in the region of the axis of the belt reel (14) with a cover (16) and a bearing for the belt reel (14) is provided in the cover (16), wherein the cover (16) has a first, pot-shaped cover part (16a) which is fastened directly to the belt retractor frame (12) and which has a side wall (24) which merges into a flat section (26), and wherein an opening (32) is recessed in the flat section (26), and a second cover part (16b) which engages in the opening (32) in the first cover part (16a) and on which a bearing (40) is formed, in which one end (42) of the axis of the belt reel (14). [2] Belt retractor according to claim 1, characterized bythat the second cover part (16b) is resilient. [3] Belt retractor according to one of the preceding claims, characterized by that the second cover part (16b) has a positioning structure (34) by means of which a radial position of the second cover part (16b) with respect to the first cover part (16a) is fixed. [4] Belt retractor according to claim 3, characterized by that the positioning structure (34) has at least one projection (35) which bears against the inner edge of the opening (32) in the first cover part (16a). [5] Belt retractor according to claim 4, characterized by that the projection (35) is circumferentially circumferential. [6] Belt retractor according to one of the preceding claims, characterized by that the first cover part (16a) is made of a metal, in particular steel, and the second cover part (16b) is made of a plastic. [7] Belt retractor according to one of the preceding claims, characterized bythat the bearing (40) is formed centrally with respect to the positioning structure (34) on the second cover part (16b). [8] Belt retractor according to one of the preceding claims, characterized by that the second cover part (16b) extends in the radial direction in sections parallel to the flat section (26) of the first cover part (16a). [9] Belt retractor according to one of the preceding claims, characterized by that the first cover part (16a) is welded to the belt retractor frame (12). [10] Belt retractor according to one of the preceding claims, characterized by that a drive wheel (15) of the belt tensioner (11) arranged concentrically with the axis of the belt reel (14) is accommodated under the cover (16).

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