Seatbelt retractor for a motor vehicle's seatbelt system

Description

[0001] The present invention relates to a belt retractor for a safety belt device of a motor vehicle with the features of the preamble of claim 1.

[0002] Seatbelt retractors for motor vehicles are permanently mounted and feature a rotatable belt shaft onto which a seatbelt can be wound. The belt shaft is rotatably mounted in a vehicle-mounted frame, which simultaneously serves to securely attach the retractor to the vehicle structure or a vehicle seat. Furthermore, a retraction spring, supported by the retractor frame, is provided. This spring biases the belt shaft in the winding direction of the seatbelt, allowing the seatbelt to be extended by tensioning the retraction spring. After extension, the belt shaft is then retracted by the tensioned retraction spring in the winding direction.It has proven effective to design the return spring as a coil spring housed within a spring housing. The spring housing is fixed to the frame of the seatbelt retractor and also serves to secure the outer end of the coil spring. The inner end of the coil spring, also known as the spring core, is fixed to the seatbelt shaft. Furthermore, the coil spring is wound in such a way that it pre-tensions the seatbelt shaft in the winding direction via the spring core, while its outer end is supported by the spring housing against the frame, ensuring a secure connection to the vehicle. The return spring is pre-assembled and fixed within the spring housing and, together with the housing, is mounted to the seatbelt retractor as a pre-assembled unit, also referred to as a spring cassette.

[0003] The frame has two opposing bearing openings, each arranged in parallel legs of the frame, in which the belt shaft is radially supported by a bearing flange. During assembly, the spring cassette is placed laterally onto a central axial extension of the belt shaft with the spring core facing upwards, secured against rotation, and fastened to one of the frame legs via the spring housing. The spring cassette is designed so that the extension of the belt shaft can be connected to the spring core with a bearing clearance of + / - 1 mm in the axial direction.

[0004] From DE 27 20 959 a belt winder is known in which the belt shaft is additionally supported in a point bearing in the spring housing via the axial extension on which the spring core is held.

[0005] From DE 10 2004 008 278 A1 a belt winder is also known in which the spring core is fixed in the spring cassette by means of a release mechanism to simplify assembly, which is then removed or destroyed when the spring core is connected to the axial extension of the belt shaft.

[0006] From DE 31 08 632 A1 a belt winder is also known in which the spring cassette is fixed to the leg of the frame by means of several spreading pins provided on the spring housing.

[0007] Another belt retractor is known, for example, from publication WO 2017 / 207695 A1.

[0008] A fundamental problem is that the return spring, designed as a coil spring, exerts forces not only circumferentially on the belt shaft. Due to its shape and the radially outer attachment to the spring housing, in conjunction with the radially inner attachment to the belt shaft, the return spring also exerts radial forces on the belt shaft and the spring housing. These radial forces must be absorbed by the belt shaft bearings and can adversely affect the winding and unwinding process of the seat belt, for example, by increasing friction in the belt shaft bearings.

[0009] Against this background, the invention aims to provide a belt retractor which is improved with regard to the winding and unwinding process of the safety belt.

[0010] To solve the problem, a belt retractor with the features of claim 1 is proposed. Further preferred developments of the invention can be found in the dependent claims, the figures, and the accompanying description.

[0011] According to claim 1, a belt retractor for a seat belt assembly of a motor vehicle is proposed to solve the problem, comprising a belt shaft rotatably mounted in a frame for winding up a seat belt of the seat belt assembly, wherein the frame has two opposing wall sections aligned parallel to each other, each with a bearing opening in which the belt shaft is rotatably mounted, and a spring housing attached to one of the wall sections with a return spring arranged therein, which is connected at a first end to the spring housing and at a second end non-rotatably to the belt shaft, wherein the spring housing is held radially elastically on the wall section, and the spring housing has a base housing with radially outwardly arranged fastening sections, and the fastening sections are connected to the base housing via elastic deformation sections.

[0012] The radially elastic mounting of the spring housing to the frame or wall section of the belt retractor frame allows the spring housing, and thus also the first end of the return spring held to it, to perform at least slight radial movements. This, in turn, reduces the radial forces acting on the belt shaft. In particular, it compensates for the radial forces exerted by the return spring itself; the return spring effectively yields by allowing its first end to move radially outwards or inwards.

[0013] Furthermore, the mounting of the spring housing is intentionally designed to be both rigid and radially elastic. This is achieved by ensuring a rigid connection via the mounting sections, while the radially elastic movement of the spring housing is achieved through the deformation sections deliberately incorporated between the base housing and the mounting sections. The radially elastic movement of the spring housing is specifically achieved through the design and arrangement of the deformation sections, while the mounting sections are designed to provide a reliable and sufficiently rigid connection for the spring housing.

[0014] It is further proposed that the mounting sections are each connected to the base housing via two deformation sections, and that the mounting sections, together with the deformation sections provided thereon, each define a clearance to the base housing. The advantage of this solution is that even if one of the deformation sections is damaged, the base housing remains reliably connected to the mounting section via the other deformation section. Furthermore, the deformation sections and the mounting sections complement each other in such a way that they define a clearance to the base housing; the deformation sections, together with the mounting section positioned between them, thus form a continuous connecting line, and mobility is achieved through the clearance formed with the base housing and the deformation of the deformation sections.

[0015] It is further proposed that four mounting sections be provided, with each pair of mounting sections arranged symmetrically to each other with respect to a central axis of the belt retractor. The proposed number and arrangement of the mounting sections allows for the most uniform and directionally neutral compensation of radial forces with respect to the central axis through a corresponding compensatory movement of the spring housing.

[0016] It is further proposed that the mounting sections be arranged such that they each form a stop, thereby limiting the radial deflection of the spring housing made possible by the deformation sections. The radial elastic mounting of the spring housing is thus limited to a maximum spring travel. The elastic spring travel of the spring housing is preferably dimensioned to be greater than the bearing clearance of the belt shaft in the bearing openings, so that the radial forces exerted on the belt shaft by the seat belt cause the belt shaft to engage in its bearings, and the mounting sections are not loaded in this case, since the spring housing does not reach its stop against the mounting sections.

[0017] It is further proposed that the spring housing has a cover firmly connected to it on its side facing the wall section, and that the cover has an annular, axially projecting collar arranged such that it engages in the bearing openings and encompasses the section of the belt shaft that extends through the bearing opening. In this case, the axially projecting collar additionally forms a bearing ring with an enlarged bearing surface in the bearing opening for the belt shaft. This eliminates the need for additional bearing shells or bearing rings in the bearing opening.

[0018] It is further proposed that the wall section in the area of ​​the bearing opening be thickened in the axial direction of the belt shaft. This proposed enhancement allows the wall section itself to form an enlarged contact or bearing surface for the belt shaft or a bearing ring.

[0019] Furthermore, it is proposed that the return spring be connected at its second end to a coupling piece in a rotationally fixed manner, which in turn is connected at its second end to the belt shaft. The coupling piece serves to connect to the belt shaft and is, for this purpose, individually equipped, e.g., with a multi-tooth or polygonal profile, while the return spring is fixedly attached or clamped at its second end to the coupling piece.

[0020] It is further proposed that an axial spring be provided between the coupling piece and the belt shaft, pressing the coupling piece into a bearing point in the spring housing. The coupling piece is rotationally fixed to the belt shaft and thus carries the rotational movements of the belt shaft. The proposed solution improves the mounting of the coupling piece, deliberately utilizing the stationary spring housing for this purpose, which simultaneously forms the attachment point for the first end of the return spring. The bearing point is preferably a spherical bearing in the form of a hemisphere or partial sphere within the spring housing, which, due to its shape, can preferably absorb both axial and radial forces in a directionally neutral manner.

[0021] It is further proposed that the axial spring be a conical spring which, due to its shape, preloads the coupling piece in both the axial and radial directions relative to the bearing point. Preloading and centering the coupling piece in the radial direction can be achieved particularly easily by having the conical spring bear against the belt shaft with its larger diameter. This allows the smaller diameter of the conical spring to bear against the coupling piece, thereby simultaneously centering it.

[0022] It is further proposed that a force-limiting device be provided with a profile head that can be locked against a blocking wall section of the frame by means of a locking pawl, and that the wall sections with the bearing openings are arranged on one side of the blocking wall section, and that the bearing clearance of the bearing opening in the wall section with the greater distance to the blocking wall section is greater than the bearing clearance of the bearing opening in the wall section with the smaller distance to the blocking wall section. This proposed improvement allows the bearing arrangement to be enhanced with regard to the bearing forces acting during activation of the force-limiting device, as the belt shaft can be deflected angularly and still run smoothly into the bearing openings.

[0023] The invention is explained below with reference to preferred embodiments and the accompanying figures. Fig. 1 shows a belt retractor with a belt shaft and a force limiting device in a sectional view of the belt shaft; Fig. 2 shows an exploded view of the belt retractor in a first perspective; Fig. 3 shows an exploded view of the belt retractor in a second perspective; Fig. 4 shows a sectional view of the belt retractor with the belt shaft and the spring cassette; Fig. 5 shows an enlarged section of the spring cassette in the area of ​​the coupling piece; Fig. 6 shows an enlarged section of the spring cassette in the area of ​​the coupling piece and the belt shaft; and Fig. 7 shows the spring cassette of the Figure 4 Looking from the left towards the spring housing; and Fig. 8 the spring cassette 5 of the Figure 4after attachment to the wall section in the direction of view from the right before insertion of the belt shaft; and Fig. 9 a belt winder with a bearing opening with a thickened wall section; and Fig. 10 a belt winder with a spring cassette with a cover with a radial annular collar.

[0024] In the Figure 1The figure shows a seatbelt retractor 1 according to the invention, comprising a seatbelt shaft 2 and a force-limiting device 6. The seatbelt shaft 2 and the force-limiting device 6 are each mounted in wall sections 3 and 4 that are aligned parallel to each other. The wall sections 3 and 4 are fixed and divide the interior of a frame (not shown), which is formed from one or more profile rails. Alternatively, the wall sections 3 and 4 can also be formed by the upwardly bent legs of a U-shaped frame. When the seatbelt retractor 1 is installed in the vehicle, the wall sections 3 and 4 are fixed to the vehicle.

[0025] The force limiting device 6 comprises a profile head 8 which can be locked in a vehicle-mounted position in a blocking wall section 7 via a locking pawl 9 and one or more concealed torsion bars which are connected or connectable at one end to the profile head 8 and at the other end to the belt shaft 2 and which, when the profile head 8 is locked, enable a force-limited extension of the safety belt by means of plastic deformation and a resulting rotation of the belt shaft 2 in the extension direction.

[0026] Furthermore, a spring cassette 5 is attached to the left end face of wall section 3, the construction of which will be explained in more detail below. The spring cassette 5 is pre-assembled and attached as a unit to wall section 3 of the belt retractor 1.

[0027] In the Figures 2 and 3The same belt retractor 1 is shown in exploded view from different perspectives, however without the force limiting device 6 and the right-hand blocking wall section 7. Figure 1 As can be seen, in each of the wall sections 3 and 4, a bearing opening 12 and 13 is provided, in which a bearing ring 10 and 11 are arranged, respectively. The bearing rings 10 and 11 increase the available bearing surface for the belt shaft 2 in the bearing openings 12 and 13, thus improving the overall bearing arrangement. Furthermore, four fastening openings 14 are provided in each of the wall sections 3 and 4, in which the spring cassette 5 is fastened via fastening pins 58.

[0028] In the Figure 4The belt shaft 2 with the spring cassette 5 and the wall sections 3 and 4 can be seen in a sectional view. The belt shaft 2 extends through the bearing openings 12 and 13, in which the bearing rings 10 and 11 are arranged. The bearing rings 10 and 11 are injection-molded plastic parts and increase the bearing surface for the sections of the belt shaft 2 that extend through the bearing openings 12 and 13. The spring cassette 5 has a hood-shaped spring housing 51 that is open on one side and closed at its open end by a disc-shaped cover 52. The spring housing 51 thus has a cavity covered by the cover 52, in which a spiral return spring 53 is arranged. The return spring 53 is connected at its first radial outer end 55 to the spring housing 51 and at its second radial inner end 54 to a coupling piece 56 and above it to the belt shaft 2 in a rotationally fixed manner.For this purpose, the coupling piece 56 has a [feature / position] in the [location]. Figure 5 The central opening 561, which can be identified, has a multi-profile design into which the belt shaft 2 engages with a correspondingly profiled extension 21 to create a rotationally fixed connection.

[0029] The spring cassette 5 is pre-assembled with a pre-tensioned return spring 53 by rotating the coupling piece 56 together with the radially inner second end 54 of the return spring 53 relative to the radially outer first end of the return spring 53 and then fixing it in the predetermined and pre-tensioned position relative to the spring housing 51 by a retaining clip 16. The coupling piece 56 is fixed in such a position that the spring cassette 5, with the pre-positioned coupling piece 56 and the multi-tooth profile arranged therein, can be slid onto the mating profile of the extension 21, and is in such a position that the fastening pins 58 of the spring housing 51 are aligned with the fastening openings 14 of the wall section 3 and can be inserted into them.After the spring cassette 5 has been installed, the retaining clip 16 is removed at the latest after the belt retractor 1 has been installed in the vehicle, so that the return spring 53 can relax and thereby exert the required return force to wind the safety belt onto the belt shaft 2.

[0030] Furthermore, an axial spring 15 in the form of a conical spring is provided, which is placed on the extension 21 before the spring cassette 5 is mounted. The axial spring 15 has a conical shape and is pushed onto the extension 21 with the coil of the larger diameter, so that this coil bears axially against the belt shaft 2. When the spring cassette 5 is placed, it, along with the coupling piece 56, axially comes into contact with the coil of the axial spring 15 with the smaller diameter. Due to its conical shape, the axial spring 15 has a centering effect for itself and for the coupling piece 56, pressing the coupling piece 56 axially against a spherical bearing point 57 in the spring housing 51.The coupling piece 56 has a semi-spherical extension on its side facing the bearing point 57, with which it comes into contact with the bearing point 57, which is designed as a spherical bearing, and is thus supported in both the axial and radial directions, as in the . Figures 5 and 6 can be seen.

[0031] The belt shaft 2 and the coupling piece 56 are designed such that the spring cassette 5 can be mounted with the coupling piece 56 relative to the belt shaft 2 with an axial tolerance of + / - 1 mm.

[0032] In the Figure 7 Is the spring cassette 5 of the Figure 4 The spring housing 51 can be seen when viewed from the left. Figure 8 Is the spring cassette 5 of the Figure 4The spring cassette 5 is inserted into the mounting holes 14 of the wall section 3 by means of the mounting pins 58. The retaining clip 16 secures the coupling piece 56 with the opening 561 and the multi-tooth profile provided therein, so that the belt shaft 2 can be inserted in a predetermined orientation with the extension 21.

[0033] The retaining pins 58 extend axially from each mounting section 59, which are connected to the spring housing 51 via elastic deformation sections 591 and 592, so that together with the mounting sections 59 they enclose a clearance 593. The deformation sections 591 and 592 are designed as curved, thin-walled webs. Furthermore, the deformation sections 591 and 592 are integrally formed with the spring housing 51 as an injection-molded plastic part. Due to their dimensions, shape, and material properties, the deformation sections 591 and 592 are elastically deformable to such an extent that the spring housing 51, with the first end 55 of the return spring 53 attached to it, can perform slight radial movements relative to the mounting sections 59.The mounting sections 59 are each flattened on their side facing the spring housing 51 to form a stop surface 594, thus limiting the possible radial movement of the spring housing 51. The gap between the stop surface 594 and the spring housing 51 in the unloaded state, i.e., the initial state without external load, is larger than the gap between the belt shaft 2 and the bearing rings 10 and 11. Therefore, the radial movements of the belt shaft 2 cannot cause the spring housing 51 to contact the stop surfaces 594, and the belt shaft 2 contacts the bearing rings 10 and 11 before radial movements occur. This prevents the stop surfaces 594 of the mounting sections 59 from being subjected to the radial forces exerted on the belt shaft 2 by the seat belt.The stop surfaces 594 are only subjected to load when the spring housing 51 is loaded and deflected due to the radial forces exerted by the return spring 53.

[0034] In the Figure 9 An alternative embodiment can be seen in which no bearing rings 10 and 11 are provided. Instead, the wall sections 3 and 4 are deformed by a forming process such as deep drawing or stamping to form axially thickened bearing sections 31 and 41 with a correspondingly enlarged radial bearing surface.

[0035] In the Figure 10 Another alternative embodiment can be seen in which bearing rings 10 and 11 are also not provided. Instead, the cover 52 of the spring cassette 5 has an annular, axially projecting collar 521, which projects into the bearing opening 12 of the left wall section 3 and encompasses the belt shaft 2 in the section passing through the bearing opening 12.

[0036] Both solutions of Figure 9 and 10 To improve the bearing of the belt shaft 2, features independent of the mobility of the spring housing 51 are provided, which have the advantage that the previously provided bearing rings 10 and 11 can be omitted.

[0037] The proposed mobility of the spring housing 51 through the provided deformation sections 591 and 592 has the advantage that the spring housing 51 itself can deflect and thereby compensate for the radial forces exerted by the return spring 53, so that the radial forces acting on the belt shaft 2 can at least be reduced. Ideally, the return spring 53 then exerts only circumferential forces on the belt shaft 2, so that its rotational movement during winding and unwinding can be significantly improved. This allows the running and bearing of the belt shaft 2 to be implemented more easily and, in particular, with less friction.

[0038] As in the Figure 1 As can be seen, wall sections 3 and 4 are arranged on the same side, here on the left side of the blocking wall section 7. In this diagram, wall section 4, which is on the right and has the bearing opening 13, has a smaller distance L1, and wall section 3, which is on the left and has the bearing opening 12, has a larger distance L3 to the blocking wall section 7. The distance L2 between the two wall sections 3 and 4 with the bearing openings 12 and 13 then corresponds to the difference between the larger distance L3 and the smaller distance L1.

[0039] The bearing opening 12 in wall section 3, with the larger distance L3 to the blocking wall section 7, has a larger bearing clearance D2, here 1.07 mm, than the bearing opening 13 in wall section 4, with the smaller distance L1 to the blocking wall section 7, which has a smaller bearing clearance D1, here 0.7 mm. Due to the proposed dimensioning of the bearing clearances D1 and D2, the belt shaft 2 runs as evenly as possible in the bearing openings 12 and 13 of wall sections 3 and 4, even when the profile head 8 is blocked and the belt shaft 2 is deflected at an angle relative to the blocking head 8. This, in turn, leads to a more even load distribution on wall sections 3 and 4, as well as on the belt shaft 2 in the area of ​​the bearing openings 12 and 13.

[0040] Furthermore, the ratio of the distance L2 between wall sections 3 and 4 to the distance L1 of the right wall section 4 to the blocking wall section 7 is approximately 2:1, or in other words, a ratio of 2 / 3 to 1 / 3. Similarly, the ratio of the distance L1 between the right wall section 4 and the blocking wall section 7 to the distance L3 between the left wall section 3 and the blocking wall section 7 is 2:3, which is ideally almost identical to the ratio of the bearing clearance D1 in the bearing opening 13 of the right wall section 4 to the bearing clearance D2 in the bearing opening 12 in the left wall section 3 of 0.7 / 1.07.

Claims

1. Belt retractor (1) for a seat belt device of a motor vehicle, comprising - a belt shaft (2), rotatably mounted in a frame, for winding up a seatbelt of the seatbelt device, wherein - the frame has two opposing wall portions (3,4) oriented in parallel with one another and each comprising a bearing opening (12,13) in which the belt shaft (2) is rotatably mounted, and - a spring housing (51) fastened to one of the wall portions (3,4) and having a return spring (53) arranged therein, which is connected by a first end (55) to the spring housing (51) and connected by a second end (54) to the belt shaft (2) for conjoint rotation, characterized in that - the spring housing (51) is radially resiliently held on the wall portion (3,4), - the spring housing (51) comprising a main housing (511) that has fastening portions (59) arranged radially on the outside, and - the fastening portions (59) being connected to the main housing (511) via resilient deformation portions (591,592).

2. Belt retractor (1) according to claim 1, characterized in that - the fastening portions (59) are each connected to the main housing (511) via two deformation portions (591,592), and - the fastening portions (59), together with the deformation portions (591,592) provided thereon, each delimit a free space (593) with respect to the main housing (511).

3. Belt retractor (1) according to any of claims 1 or 2, characterized in that - four fastening portions (59) are provided, and in each case two fastening portions (59) are arranged symmetrically to one another in relation to a central axis (M) of the belt retractor (1).

4. Belt retractor (1) according to any of claims 1 to 3, characterized in that - the fastening portions (59) are arranged in such a way that they each form a stop that limits the radial deflection of the spring housing (51) made possible by the deformation portions (591,592).

5. Belt retractor (1) according to any of claims 1 to 4, characterized in that - the spring housing (51) comprises a cover (52) which is rigidly connected to the spring housing (51) on the side of the spring housing that faces the wall portion (3,4), and - the cover (52) comprises an annular, axially projecting collar (521) which is arranged in such a way that it engages in the bearing openings (12,13) and encompasses the portion of the belt shaft (2) that passes through the bearing opening (12,13).

6. Belt retractor (1) according to any of claims 1 to 5, characterized in that - the wall portion (3,4) in the region of the bearing opening (12,13) is thickened in the axial direction of the belt shaft (2).

7. Belt retractor (1) according to any of claims 1 to 6, characterized in that - the return spring (53) is connected by the second end (54) to a coupling piece (56) for conjoint rotation, which coupling piece is connected to the belt shaft (2) for conjoint rotation.

8. Belt retractor (1) according to claim 7, characterized in that - an axial spring (15) which urges the coupling piece (56) into a bearing (57) of the spring housing (51) is provided between the coupling piece (56) and the belt shaft (2).

9. Belt retractor (1) according to claim 8, characterized in that the bearing (57) is a spherical bearing in the form of a hemisphere or partial sphere in the spring housing (51).

10. Belt retractor (1) according to claim 8 or claim 9, characterized in that - the axial spring (15) is a conical spring.

11. Belt retractor (1) according to claim 10, characterized in that - the larger diameter of the conical spring is supported on the belt shaft (2).

12. Belt retractor according to any of claims 1 to 11, characterized in that - a force limiting device (6) is provided which has a profile head (8) that can be blocked with respect to a blocking wall portion (7) of the frame by means of a blocking pawl (9), and - the wall portions (3,4) having the bearing openings (12,13) are arranged on one side of the blocking wall portion (7), and - the bearing clearance (D2) of the bearing opening (12) in the wall portion (3) at the greater distance (L3) from the blocking wall portion (7) is greater than the bearing clearance (D1) of the bearing opening (13) in the wall portion (4) at the smaller distance (L1) from the blocking wall portion (7).