Rotary tensioner for seat belts

Abstract

The present invention relates to a rotary tensioner for a seat belt, comprising a drive mechanism in the form of a mass chain (3) guided within a tube (5) through which compressed gas is supplied, wherein the mass chain comprises a drive wheel (1) consisting of a plurality of identical individual masses (4) and rotatably fixed to the belt reel (10), and uniformly arranged on the radially outer surface and having a plurality of recesses (2) having a shape corresponding to at least one sub-part of the outer shape of the individual masses (4), the drive wheel being driven when the drive mechanism is activated The present invention relates to a rotary tensioner, which is rotatable around a rotation axis (D), the recesses (2) being sized to accommodate the corresponding individual masses (4) of the mass chain (3) in each of the recesses (2), the forming element (6) being positioned at the end of the mass chain (3) facing the drive wheel (1), and the forming element (6) having a flat support surface (14) on the forming element surface facing the first individual mass (4) of the mass chain (3) in at least the region of the second sub-mass (9), thereby the forming element (6) resting on the first individual mass (4).

Description

Technical Field

[0001] The present invention relates to a rotary tensiomer for a seat belt having the features of the preamble of claim 1.

Background Art

[0002] The basic design of such a rotary tensiomer is known from European Patent No. 0755340 (B1). In this rotary tensiomer, a mass body chain consisting of spherical individual masses is launched onto a drive wheel by the operation of a pyrotechnic propellant, and this drive wheel has recesses that match the shape of the individual masses. Therefore, the individual masses engage with the recesses and drive the drive wheel in a rotational driving motion. The drive wheel can be connected to rotate permanently or via a coupling to the belt shaft of the belt winder, and the belt winder can wind up the seat belt. The rotational driving motion of the drive wheel is converted via a fixed connection or coupling into a rotational motion of the belt shaft in the winding direction, whereby the seat belt is wound up on the belt shaft and tension is applied. It is also conceivable to transmit the driving motion of the drive wheel to the belt buckle or end fitting via appropriate power transmission means. The individual masses of the mass chain are guided through a tube whose ends are closed by a pyrotechnic propellant, and this propellant is introduced into the pressure chamber between the propellant and the first individual mass or piston during operation to suddenly generate a very large gas flow that drives the mass body chain.

[0003] One problem to be solved with such a rotary tensiomer is that the individual masses must be in a shape-fitting engagement with the recesses in order to ensure an unobstructed operation of the driving motion.

[0004] To solve this problem, International Publication No. 01 / 00460 (A1) has already proposed providing a shaping element having a finder part in the form of a first sub-mass between the first individual masses facing the drive wheel, and having finder parts in the form of the first sub-mass and the second sub-mass, and being connected to the first sub-mass via a connecting rib for synchronous control of the individual masses into the recess.

[0005] Here, the partially formed contour of the first secondary mass of the molded element, called the finder portion, allows the molded element having the finder portion to engage with one of the recesses, regardless of the position of the drive wheel. During further driving motion, the molded element can cause a position correction of the drive wheel by rotating at a specific angle until the molded element reaches a position where it enters the subsequent recess synchronously with the second secondary mass, through the engagement of the finder portion. Since the individual mass is in a predetermined orientation relative to the second secondary mass of the molded element, during the subsequent movement of the mass chain and the drive wheel, the individual mass is introduced into the subsequent recess of the drive wheel, thereby driving the drive wheel synchronously.

[0006] One problem with such rotary tensioners is that, in a point-like arrangement, the forming element rests on the first individual mass of the mass chain and can therefore tilt relative to it, causing the forming element with the finder portion to pivot against the inner wall of the tube, and in extreme cases, wedging itself between the drive wheel and the tube. This wedging of the forming element creates an additional resistance force that the tensioner drive mechanism must overcome, thus reducing its tensioning performance. In extreme cases, the wedging of the forming element can also lead to interference with the tensioning motion or mechanical damage to the tube or drive wheel, which at least adversely affects the subsequent tensioning drive motion. [Overview of the project]

[0007] Against this backdrop, the present invention aims to improve the rotary tensioner of the type in question to such an extent that the possibility of the molding element tilting, and therefore the possibility of interference with the tensioning operation, is reduced.

[0008] To achieve the objective, a rotary tensioner having the features of claim 1 is proposed. Further preferred developments can be derived from the dependent claims, figures, and related descriptions.

[0009] According to the basic concept, claim 1 proposes that the molding element has a support surface formed by a flattening portion on the side facing the first individual mass of the mass chain, at least in the region of the second secondary mass, and that the molding element rests on the first individual mass by this support surface. Due to the flat support surface, the first individual mass rests on a flat contact surface rather than a curved contact surface on the molding element, thereby reducing the lateral deflection of the molding element relative to the first individual mass, or vice versa, the tilt moment acting thereon. This cancels out the tendency for the molding element to tilt relative to the first individual mass, tube, and drive wheel.

[0010] Furthermore, it is proposed that the support surface has a larger extension in the direction away from the drive wheel than in the direction toward the pipe side facing the drive wheel, starting from the center of the molded element. This allows the first individual mass to rest on a flat support surface over a longer portion in the case of such deflection than in the case of the opposite deflection, thus intentionally counteracting the tendency of the molded element to tilt toward the drive wheel together with the second secondary mass. The corresponding lower support of the molded element when tilted in the other direction is acceptable insofar as the deflection in this direction is limited by the pipe wall side facing away from the drive wheel.

[0011] Furthermore, it is proposed that the support surface is formed by an elongated surface having a constant width with respect to the longer central axis, at least in the central part of the width direction of the drive wheel parallel to the rotation axis of the drive wheel, and positioned symmetrically with respect to the first central axis of the molding element. The pressure applied to the molding element by the first individual mass is converted into a circumferential force applied to the drive wheel, and the pressure is redirected. This deflection and contact with the drive wheel cause tilting and jamming of the molding element. The direction of the force redirection also results in a preferred direction of inclination, which is taken into account by the elongated shape having a longer extension of the support surface on one side. In the direction parallel to the rotation axis of the drive wheel, the pressing force acts symmetrically, and there is no preferred direction of inclination of the molding element; as a result, the first individual mass does not have a preferred direction of deflection relative to the molding element. For this reason, the support surface is designed to have a constant width in this direction and is positioned symmetrically with respect to the first central axis of the molding element. This results in directionally neutral support of the molding element by the first individual mass with respect to this direction.

[0012] Furthermore, it is proposed that the support surface has a linear orientation in a plane perpendicular to the rotation axis of the drive wheel. Due to the linear orientation, the support surface forms a linear support surface when the molded element is tilted laterally, and thus more effectively counteracts the tendency of the molded element to tilt. In this process, the molded element rotates on its linear support surface over the surface of the first individual mass of the second submass, and the possible rotation angle of the molded element is reduced by the linear design of the support surface compared to conventionally used curved support surfaces.

[0013] Furthermore, it is proposed that the support surface has a curvature that forms a groove in the extended portion oriented parallel to the rotation axis of the drive wheel. The proposed curvature of the support surface in the extended portion parallel to the rotation axis of the drive wheel improves the support of the molded element in the case of inclination, even in this direction by the first individual mass, by reducing the possible angle of rotation of the molded element with respect to the first individual mass. Since the curvature of the support surface is oriented in the opposite direction to the outward curvature of the molded element in the region of the second sub-mass, the support surface forms a groove in the second individual mass.

[0014] The present invention will be described below using preferred embodiments with reference to the attached figures. [Brief explanation of the drawing]

[0015] [Figure 1] This shows a rotary tensioner with individual parts before assembly. [Figure 2] The molded elements are shown in a perspective view as individual parts. [Figure 3] The second submass shows the molding element in the diagram. [Figure 4] This is a cross-sectional view of a rotary tensioner according to prior art, which has a drive wheel and a molded element that engages with the drive wheel. [Figure 5] This is a cross-sectional view of a rotary tensioner according to the present invention, which includes a drive wheel and a molding element that engages with the drive wheel. [Figure 6] The molding element in the side view of the second secondary mass is shown. [Modes for carrying out the invention]

[0016] Figure 1 shows a rotary tensioner having a drive wheel 1, a tube 5, and a drive device in the form of a mass chain 3 guided inside the tube 5, which consists of a plurality of individual masses 4 and a molding element 6 located on the end face of the mass chain 3 on the first individual mass 4. The individual masses 4 are formed as spheres, and the drive wheel 1 has a recess 2 formed in the form of a hemispherical half-shell or cap that matches the shape of the individual masses 4.

[0017] The drive wheel 1 is connected to a belt reel 10 capable of winding a seat belt (not shown) of a seat belt device, so as to rotate together with the wheel. The belt reel 10 itself is rotatably mounted within a frame 11 that can be mounted on the vehicle. Furthermore, a tube 5 is provided, within which a mass chain 3 is positioned and guided, and a gas generator 15 is attached to the end of the tube 5, for example, by crimping. Further, a first tensioner housing half 13 and a second tensioner housing half 12 are provided, mounted on the outside of the frame 11 and securing the tube 5 with the mass chain 3 to the frame 11. The first tensioner housing half 13 is directly mounted to the frame 11, and the second tensioner housing half 12 is mounted to the first tensioner housing half 13 and therefore indirectly mounted to the frame 11. In addition to securing the pipe 5, the first tensioner housing half and / or the second tensioner housing half 13 and 12 function to guide the individual mass 4 after it exits the pipe 5 and engages with the drive wheel 1.

[0018] The molding element 6 according to the prior art and the molding element 6 according to a further developed form of the present invention can be seen in Figures 4 and 5 at the engagement position within the drive wheel 1. The basic structure of the two molding elements 6 is identical and comprises finder portions in the form of a first sub-mass 7 and a second sub-mass 9, the second sub-mass 9 being connected to the first sub-mass 7 via a connecting rib 8.

[0019] The first submass 7 and the second submass 9 are each formed by partially formed individual masses 4, that is, by completing the shapes of the first submass 7 and the second submass 9, they will have the same shape as the individual mass 4. Furthermore, the first and second submasses 7 and 9 are designed such that the distance between the centers of the bodies of the virtual shape-completed individual masses 4 of the molded element 6 is the same distance as the distance between the centers of the bodies of the individual masses 4 of the mass body chain 3 that engages with the recess 2 and are continuous with each other, and they are connected to each other via connecting ribs 8. Thus, the molded element 6 can be understood as two incompletely formed individual masses 4 connected to each other via connecting ribs 8.

[0020] The molding element 6 of the rotary tensioner, further developed according to the present invention, can be seen as an individual part in a perspective view in Figure 2 and in an end view of the second sub-mass 9 in Figure 3. The molding element 6 has a support surface 14 on the end face of the second sub-mass 9, which is designed as an elongated ellipse with two parallel edge surfaces. The support surface 14 is formed in the form of a flat portion formed by a virtual cross-section passing through the second sub-mass 9, and its shape is defined by the shape of the body of the second sub-mass 9 in the region of the cross-section.

[0021] The support surface 14 is formed and positioned such that the molded element 6 having the support surface 14 rests on the first individual mass 4 of the mass body chain 3, as can be seen in Figure 5. The support surface 14 is formed and positioned such that the longer central axis L of the support surface 14 has a linear direction perpendicular to the rotation axis D of the drive wheel 1, and the rotation axis D of the drive wheel 1 extends perpendicularly through the diagrammatic plane in Figure 5.

[0022] The support surface 14 has two edge sides oriented parallel to each other and parallel to the central axis L, the distance between them defining a constant width B of the flat part 14, which is preferably 3.0 mm, at least in the central part. The central axis L of the support surface 14 corresponds to the first central axis M1 of the forming element 6. Furthermore, the support surface 14 is oriented symmetrically with respect to the central axis L and the first central axis M1 of the forming element 6, so that the forming element 6 having the support surface 14 is placed symmetrically with respect to the first individual mass 4 on both sides of the first central axis M1. The support surface 14 is further shaped and arranged so as to be arranged asymmetrically with respect to a second central axis M2 oriented perpendicular to the first central axis M1. Starting from the center of the forming element 6 defined by the second central axis M2, the support surface 14 has a smaller extension H1 of about 1.5 to 2.0 mm in one direction and a larger extension H2 of 2.5 to 3.2 mm in the other direction. For this purpose, the forming element 6 in the region of the second secondary mass 9 is designed in its basic form such that the different extensions H1 and H2 result only from the arrangement of the virtual cross-section passing through the body of the second secondary mass 9. The forming element 6 is preferably manufactured as an integrally injection-molded part already in its final shape in an injection molding process, for example as a plastic injection-molded part, so that the term "cross-section" should of course not be understood in the sense of a cut or any other subsequent treatment of the forming element 6. The term "cross-section" is only intended to provide a simplified concept of the shape of the support surface 14.

[0023] The forming element 6 is arranged in the tube 5 of the rotary tensioner such that the support surface 14 having the larger extension H2 is directed towards the wall of the tube 5 facing away from the drive wheel 1, while the smaller extension H1 is directed towards the wall of the tube 5 facing the drive wheel 1. Thus, the support surface 14 forms an asymmetric support of the forming element 6 perpendicular to the rotation axis D of the drive wheel 1 and a symmetric support of the forming element in the direction of the rotation axis.

[0024] Figure 4 shows a rotary tensioner according to the prior art. The forming element 6 does not have a flat support surface 14, but instead has a curved or hemispherical surface in the region of the second secondary mass 9. As can be seen in Figure 4, under unfavorable force conditions, the forming element 6 is inclined in the direction of the drive wheel 1 together with the second secondary mass 9 due to the pressure applied by the first individual mass 4, and the forming element 6 rotates on the surface of the first individual mass 4 with a relatively large rotation angle together with the surface of the second secondary mass 9. This rotation is facilitated by the curved surface of the forming element 6 in the region of the second secondary mass 9 and the curved surface of the first individual mass 4.

[0025] Figure 5 shows a further developed rotary tensioner according to the present invention. The forming element 6 has a flat support surface 14 in the region of the end face of the surface of the second secondary mass 9. The forming element 6 is oriented such that the support surface 14 having a longer extension H2 faces the left wall of the tube 5, that is, the wall of the tube 5 facing away from the drive wheel 1. This is advantageous because the forming element 6 is thereby supported particularly against the inclination direction shown in Figure 4. The displacement of the forming element 6 to the other side with the first secondary mass 9 is restricted by the wall of the tube 5 anyway, so the flat support surface 14 has a shorter extension H1 towards the other side, that is, in the direction of the drive wheel 1.

[0026] Therefore, the flat support surface 14 has a preferred support direction for the forming element 6 against the inclination towards the second secondary mass 9 in the direction of the drive wheel 1 about a pivot axis oriented parallel to the rotation axis D. Due to the symmetric design of the support surface 14 with respect to the first central axis M1, the forming element 6 is supported equally in both pivot directions, that is, directionally neutrally, when inclined about a pivot axis that is perpendicular to the rotation axis D and horizontal in the figure.

[0027] In Figure 6, the molded element 6 can be viewed as a separate part from the perspective of a second submass 9 having a support surface 14 positioned on the lower side in the view in the direction of the first central axis M1 in Figure 3. The flat support surface 14 has a curvature R that forms the flat support surface 14 in a groove in this direction. For this purpose, the curvature R is oriented in the opposite direction to the curvature of the outer surface of the molded element 6 in the region of the second submass 9, and as a result, the support surface 14 is recessed into the second submass 9. The curvature R has a preferred radius of 20 mm.

[0028] The negative curvature R directed towards the second submass 9 further reduces the possible rotation angle of the molding element 6 in the first individual mass 4 in this direction. If the curvature R corresponds to the curvature of the outer shape of the first individual mass 4, this can even result in planar contact of the molding element 6 with the first individual mass 4.

Claims

1. A rotating tensioner for seat belts, - A drive device in the form of a mass chain (3) guided within a pipe (5) through which compressed gas is supplied, wherein the mass chain consists of a plurality of identical individual masses (4) to drive a belt reel (10) in the winding direction of the seat belt. - A drive wheel (1) is rotatably fixed to the belt reel (10), and has a plurality of recesses (2) uniformly arranged on the radial outer surface and having a shape that matches at least one sub-part of the outer shape of the individual mass (4), and the drive device is equipped with a drive wheel (1) that is rotatable about a rotation axis (D) when the drive device is operated, - The recesses (2) are sized such that each of the corresponding individual masses (4) of the mass chain (3) can be received into the recesses (2). - A molding element (6) is positioned at the end of the mass chain (3) facing the drive wheel (1), - The molded element (6) has a first sub-mass (7) that forms a finder portion in the form of a partially molded individual mass (4), and a second sub-mass (9) connected to the first sub-mass (7) via connecting ribs (8) in the form of at least a partially molded individual mass (4), - A rotary tensioner characterized in that the molding element (6) has a support surface (14) formed by flattening, and the molding element (6) is placed on the first individual mass (4) of the mass chain (3) on the surface of the molding element that faces the first individual mass (4) of the mass chain (3) in the region of the second sub-mass (9).

2. - The rotary tensioner according to claim 1, characterized in that the support surface (14) has a larger extension (H2) in the direction toward the pipe (5) that is away from the drive wheel (1) than toward the pipe (5) that faces the drive wheel (1), starting from the center of the molding element (6).

3. - The rotary tensioner according to claim 1 or 2, characterized in that the support surface (14) has a constant width (B) with respect to the longer central axis (L) at least in the central portion in the direction of the width of the drive wheel (1) parallel to the rotation axis (D) of the drive wheel (1), and is formed by an elongated surface that is arranged symmetrically with respect to the first central axis (M1) of the molding element (6).

4. - The rotary tensioner according to any one of claims 1 to 3, characterized in that the support surface (14) has a linear orientation in a plane perpendicular to the rotation axis (D) of the drive wheel (1).

5. - The rotary tensioner according to any one of claims 1 to 4, characterized in that the support surface (14) has a curvature that forms a groove in an extended portion oriented parallel to the rotation axis (D) of the drive wheel (1).

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