Self-locking belt retractor for a motor vehicle's seat belt system

Abstract

The invention relates to a self-locking belt retractor for a seat belt system of a motor vehicle, comprising: - a two-part belt shaft (1) with a belt shaft body (12) and a profile head (2), wherein a first stop (6) is provided on the belt shaft body (12), and a second stop (5) is provided on the profile head (2), and - a blocking element (3) is provided, which, during a rotational movement of the belt shaft body (12) in the belt extension direction during activation of the force limiting device (11), comes into contact with the second stop (5) of the profile head (2), wherein the blocking element (3), in the blocking position at the second stop (5), limits the rotational movement of the belt shaft body (12) by a blocking contact of the first stop (6) of the belt shaft body (12) with the blocking element (3).

Description

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

[0002] Seat belt systems in motor vehicles serve to restrain an occupant in an accident to prevent serious injuries. These systems comprise a seat belt, one end of which is fixed to the vehicle via an end fitting, and the other end of which is attached to a belt shaft of a fixed belt retractor. Furthermore, the seat belt features a sliding tongue that can be locked into a buckle, also fixed to the vehicle, to create a three-point locking mechanism.

[0003] The seatbelt retractor can be locked in the event of an accident by means of a locking device, which is controlled by a vehicle-sensitive and / or belt-sensitive sensor device, if predetermined acceleration values ​​of the belt extension speed or predetermined deceleration values ​​of the vehicle are exceeded, thus preventing further extension of the seatbelt and subsequently restraining the occupant. The locking device comprises a locking pawl which can be controlled by the sensor device to engage a toothed section fixed to the vehicle in the belt retractor. Furthermore, it is known to provide one or more force limiting devices, acting in parallel or in series, in the belt retractor. When the belt shaft is locked, these devices allow further force-limited belt extension according to a predetermined force limiting characteristic, thereby reducing the occupant's load in the event of a restraint.

[0004] The belt shaft is designed in two parts, comprising a profile head on which the locking pawl is mounted and a belt shaft body on which the safety belt is wound. The force limiting devices are positioned between the profile head and the belt shaft body and are activated by the locking of the profile head via the locking pawl and a subsequent exceedance of the belt pull-out force defined by the force limiting devices.

[0005] A proven embodiment of a force-limiting device is a torsion bar which extends through a cavity of the belt shaft body and is non-rotatably connected at one end to the belt shaft body and at the other end to the profile head. The force-limiting level of this device is defined by the plastic deformation limit of the torsion bar when a torque acts on the longitudinal axis of the torsion bar. Such a belt retractor is known, for example, from EP 2 409 882 A1.

[0006] From German patent application DE 10 2018 106 664 B4, a self-locking belt retractor with a force-limiting device in the form of a torsion bar is known. In this device, the effect of the force-limiting device—i.e., the plastic deformation of the torsion bar to achieve a stop characteristic of the force-limiting curve (LLS)—is bridged by an insert part with a thread that is fixed to the profile head in a rotationally fixed manner after a stop has been reached. The insert part is screwed into a form-corresponding thread in the belt shaft body via the thread, thus allowing relative rotation of the belt shaft body to the profile head during activation of the force-limiting device until the stop has been reached. After reaching the stop, rotation of the belt shaft body relative to the profile head is no longer possible; the profile head and the belt shaft body then effectively form a rotationally fixed connection.

[0007] One disadvantage of this solution is the complex manufacturing of the insert part with the thread and the additional machining of the belt shaft body required to produce the form-corresponding thread.

[0008] Against this background, the invention is based on the objective of providing a self-locking belt retractor with a force limiting device with a stop characteristic, which should be more cost-effective to manufacture.

[0009] To solve the problem, a self-locking seatbelt retractor with the features of claim 1 is proposed. Further preferred developments can be found in the dependent claims, the figures, and the accompanying description.

[0010] According to the basic concept of the invention, it is proposed that a first stop be provided on the belt shaft body, and a second stop be provided on the profile head, and that a blocking element be provided which, during a rotational movement of the belt shaft body in the webbing extension direction during activation of the force-limiting device, comes into contact with the second stop of the profile head, wherein the blocking element, in this blocking position against the second stop, limits the rotational movement of the belt shaft body by blocking the first stop of the belt shaft body against the blocking element. With the proposed solution, the rotational movement of the belt shaft body during the force-limited extension movement of the seat belt is limited by simple means to a predetermined rotation angle of the belt shaft body, i.e., to a predetermined extension length of the seat belt.

[0011] It is further proposed that an annular guide groove be provided on the belt shaft body, interrupted by the first stop. The locking element engages in the guide groove with a first section and projects beyond the guide groove with a second section, extending into the plane perpendicular to the axis of rotation of the belt shaft body, in which the second stop of the profile head is located. The guide groove serves to guide the locking element during rotation and additionally holds the locking element in position against acting radial forces. Since the second section of the locking element also projects into the plane of the second stop, the second stop stops the locking element during rotation, thus limiting the rotation of the belt shaft body.

[0012] It is further proposed that the locking element is fixed in position within the guide groove by a breakaway pin. The breakaway pin forms a releasable connection between the locking element and the belt shaft body, so that in an initial phase the locking element is deliberately carried along by the belt shaft body and only then is it blocked by contact with the second stop. The breakaway pin breaks off when the locking element is engaged, thus terminating the connection between the locking element and the belt shaft body. The belt shaft body can be provided with several openings, particularly blind holes, in various rotational angle configurations. The locking element with the breakaway pin can be fixed in these openings in different rotational angle configurations, allowing the maximum rotational angle of the belt shaft body to be adjusted to different angles during the force-limited extension movement of the safety belt.

[0013] It is further proposed that the blocking element, at least in its first section, has a radial extent corresponding to the radial extent of the guide groove. With the proposed design, the blocking element rests in the guide groove without play, apart from any manufacturing tolerances in the radial direction.

[0014] Furthermore, the first stop, the second stop, and the blocking element are arranged on an identical radius relative to the axis of rotation of the belt shaft. This proposed arrangement allows for a particularly compact design of the belt retractor. It also simplifies the interaction of the sections or components during the rotation of the belt shaft and the required stop action.

[0015] It is further proposed that the blocking element be positioned between the first and second stops at the beginning of the belt shaft's rotation relative to the profile head. The profile head, belt shaft, and blocking element thus form a compact assembly. It is further proposed that the blocking element be arranged upstream of the belt shaft body's rotation in the belt extension direction within a system at the first stop. Thus, when the profile head is blocked and the belt shaft body rotates in the retraction direction, the blocking element and the two stops form a rotationally fixed connection, while the blocking element and the belt shaft body can rotate when the force limiting device is activated in the extension direction of the seat belt.

[0016] It is further proposed that the first stop and the second stop each have two lateral stop surfaces extending radially through the axis of rotation of the belt shaft body, and that the blocking element is formed by a ring segment with radially oriented end faces extending through the axis of rotation of the belt shaft body. The proposed design of the stop surfaces and the end faces of the blocking element results in a planar contact surface, thus enabling the most even possible force transmission between the parts.

[0017] It is further proposed that the blocking element exhibits a higher deformation strength than the profile head and the belt shaft body. Thus, in the blocked position of the belt shaft body, the blocking element forms a dimensionally stable blocking element between the belt shaft body and the profile head. Due to its higher deformation strength, this blocking element prevents the belt shaft body from continuing its rotational movement by deforming the blocking element itself when it is blocked.

[0018] The invention is explained below with reference to a preferred embodiment and the accompanying figures. Fig. 1 A two-part belt shaft of a belt winder according to the invention with a profile head, a belt shaft body, a force limiting device arranged between them and a blocking part before assembly in side view Fig. 2 the profile head, the belt shaft body and the blocking part in frontal view; and Fig. 3. The two stops on the profile head and the belt shaft body with the blocking part inserted between them in an enlarged view; and Fig. 4 An exploded view of a belt winder according to the invention with the two-part belt shaft.

[0019] In the Fig. 1 shows a two-part belt shaft 1 of a self-locking belt retractor according to the invention, which is mounted in a known manner in a Fig. The belt retractor is rotatably mounted on a vehicle-mountable frame 200, as shown in Figure 4. The two-part belt shaft 1 serves to wind up a safety belt (not shown) and is spring-tensioned in the winding direction of the safety belt by a drive spring supported in a spring cassette 100, the spring cassette 100 itself being supported against the frame 200. The belt retractor also optionally includes a tensioner housing 300 supported against the frame 200, a sensor housing 400 supported against the tensioner housing 300, and a cover 500 also supported against the tensioner housing 300. The belt retractor is part of a safety belt system, which also includes an end fitting for attaching the free end of the safety belt to the vehicle structure, a belt tongue that is slidably guided on the safety belt and a belt buckle fixed to the vehicle in which the belt tongue can be locked in a known manner.Furthermore, depending on the arrangement and design of the safety belt device, a height adjuster, a belt deflector, a buckle tensioner, an end fitting tensioner or a belt tensioner may be provided on the belt shaft 1.

[0020] The two-part belt shaft 1 comprises a profile head 2, a belt shaft body 12, and a force-limiting device 11 in the form of a torsion bar as basic components, wherein the torsion bar connects the profile head 2 and the belt shaft body 12 to form a rotationally fixed assembly in the assembled state. Instead of the torsion bar, other forms of the force-limiting device 11 are also conceivable, provided they connect the belt shaft body 12 and the profile head 2 to form a rotationally fixed assembly and, upon activation, allow a force-limited extension of the belt. The profile head 2 carries a locking device in the form of an invisible locking pawl, which is pivotably mounted on the profile head 2 and can be controlled, via a vehicle acceleration-sensitive and / or belt acceleration-sensitive sensor device, to initiate a deflection movement into a vehicle-mounted toothing of the frame when predetermined limit values ​​are exceeded.This means that the profile head 2 is blocked in the extension direction of the webbing wound onto the belt shaft body 12 by a locking pawl engaged in the vehicle-mounted toothing. In the present embodiment, a drive wheel 20 of a pyrotechnic belt tensioner is also provided on the profile head 2. If the belt retractor does not have a pyrotechnic belt tensioner, the drive wheel 20 can be omitted.

[0021] The profile head 2 and the belt shaft body 12 each have a [feature / position] in the Fig. The profile recesses 13 and 10, which are formed by a toothed or polygonal profile and are shaped to correspond to the correspondingly shaped ends of the torsion bar, are thus fixed to the profile head 2 and the belt shaft body 12 with its ends inserted into the profile recesses 13 and 10, thereby connecting them to form the torsionally fixed assembly of the two-part belt shaft 1.

[0022] On the end face of the belt shaft body 12 facing the profile head 2, a projecting first annular wall 8 with a radially outwardly projecting first finger-shaped stop 6 is provided. On the end face of the profile head 2 facing the belt shaft body 12, an axially projecting second annular wall 9 of identical shape with a radially projecting second finger-shaped stop 5 of identical shape is also provided. Furthermore, an annular extension 7 is provided radially outward on the belt shaft body 12, which is arranged radially outward relative to the first stop 6 and, in the assembled state, extends axially beyond the first annular wall 8 to the drive wheel 20, i.e., axially beyond the second annular wall 9 and the second stop 5. The annular extension 7 thus defines a guide groove 4 for the first annular wall 8 in the belt shaft body 12, which is interrupted by the first stop 6.

[0023] With regard to the direction of rotation of the belt shaft body 12 in the extension direction of the belt, a breakaway pin 8 is provided upstream of the first stop 6, on which an annular segment-shaped blocking element 3 is fixed in the circumferential direction in the assembled position. The direction of rotation of the belt shaft body 12 during an extension movement of the belt is shown in the right-hand illustration of the Fig. 2 marked with arrow direction A.

[0024] The locking element 3 engages with a first section in the guide groove 4 and has a radial extension in this section corresponding to the radial width of the guide groove 4. The stops 5 and 6 on the profile head 2 and on the belt shaft body 12 each have two lateral flat stop surfaces 14, 15 and 16, 17, which are oriented such that they extend along the imaginary radial line through the axis of rotation of the belt shaft 1 and the belt shaft body 12, respectively. The locking element 3 is segment-shaped and has two flat end faces 18, 19, which, in the assembled position of the locking element 3, also extend along the imaginary radial line through the axis of rotation of the belt shaft 1 and the belt shaft body 12. In the assembled position, the blocking part 3 lies with its end face 18 upstream in the direction of rotation A, flush against the lateral stop surface 17 of the first stop 6 of the belt shaft body 12.The assembled position of the blocking part 3 in relation to the stops 5 and 6 is also shown in the . Fig. 3. The curvature of the ring-segment-shaped blocking part 3 corresponds to the curvature of the guide groove 4, and the radial extent of the blocking part 3 corresponds to the radial width of the guide groove 4, so that the blocking part 3 bears radially inwards against the outer surface of the ring wall 8 and radially outwards against the inner surface of the ring extension 7. The profile head 2 is positioned such that it is connected to the end of the torsion bar in a rotationally fixed and positively locking manner and, at the same time, bears downstream with the stop surface 15 on the end face 19 of the blocking part 3 via the radially outwardly projecting second stop 5.

[0025] The profile head 2 and the belt shaft body 12, with their annular walls 8 and 9 and stops 5 and 6, are shaped and arranged such that the annular walls 8 and 9 and the stops 5 and 6 are arranged in two parallel planes and can therefore rotate relative to each other. The blocking element 3 is designed with an axial width such that its first section extends into the guide groove 4 and its second section extends into the plane of the annular wall 9 and the second stop 5 of the profile head 2. Thus, the blocking element 3 is positioned circumferentially between the two stops 5 and 6 and rests radially on the inner sides of the annular walls 8 and 9 and radially on the outer sides of the inner wall of the annular extension 7.Simultaneously, the blocking element 3 is supported with its axial end faces on one side by the base surface of the guide groove 4 and on the other side by the base surface of the profile head 2, which adjoins the ring wall 9 radially outwards. In the assembled position, the blocking element 3 is thus supported on all sides between the profile head 2 and the belt shaft body 12 and is simultaneously fixed in position circumferentially by the breakaway pin 8.

[0026] The initial position of stops 5 and 6 and of the blocking part 3 in the assembled position is shown in the Fig. Figure 3 shows the rotational movement of the belt shaft body 12 during the extension movement of the webbing, indicated by the direction of arrow A. With respect to the rotational movement of the belt shaft body 12, the first stop 6 is located at the front and the second stop 5 at the rear, and the locking element 3 is located between the stops 6 and 5. In other words, with respect to the rotational movement of the belt shaft body 12, the first stop 6 is located downstream of the locking element 3 and the second stop 5 is located upstream of the locking element 5.

[0027] In principle, the force-limited extension of the webbing is triggered in an early phase of the accident by first blocking the profile head 2 in the extension direction via the blocking device. If, in a second step, the extension force exerted by the webbing then exceeds the force threshold defined by the force limiting device 11, which in this embodiment is defined by the plastic deformation limit of the torsion bar, the webbing shaft body 12 then begins to rotate in the direction of arrow A relative to the blocked profile head 2, activating the force limiting device 11.

[0028] The belt shaft body 12 rotates with the first stop 6 and the blocking part 3, which is fixed in position by the breakaway pin 8, in the direction of arrow A. During this process, the distance between the blocking part 3 and the second stop 5 of the blocked profile head 2 increases, and the blocking part 3 loses contact between its end face 18 and the stop surface 14 of the second stop 5. The belt shaft body 12 then continues to rotate, thus activating the force-limiting device and resulting in a force-limited belt extension with a force-limiting level defined by the plastic deformation limit of the torsion bar. The blocking part 3 is positioned behind the first stop 6, i.e., upstream of the first stop 6, with respect to the direction of rotation of the belt shaft body 12, as also shown in the Fig. 3 can be seen. During the further rotational movement, the first stop 6 passes the second stop 5, and the blocking part 3, due to the second section projecting into the plane of the first stop 5, comes to rest with its front end face 19 against the rear stop surface 15 of the second stop 5. This contact of the blocking part 3 against the second stop 5 blocks the blocking part 3 against further rotation, causing the breakaway pin 8 to break off. The positive locking connection between the belt shaft body 12 and the blocking part 3 is thus broken, and the belt shaft body 12 can subsequently continue to rotate relative to the blocked blocking part 3.The first stop 6 loses contact with the end face 19 of the blocking element 3 and then continues to rotate, increasing the distance to the blocking element 3, until the front stop surface 16 of the first stop 6 comes into contact with the rear end face 18 of the blocking element 3. Thus, with respect to the direction of rotation of the belt shaft body 12 during the force-limited belt extension, the first stop 6 is positioned behind the blocking element 3, i.e., upstream of the blocking element 3. Since the blocking element 3 itself is blocked due to contact with the second stop 5 of the profile head 2, the first stop 6 and, above it, the belt shaft body 12 as a whole are blocked against further rotation in the belt extension direction. Because the belt shaft body 12 is blocked, the force-limited belt extension is stopped to achieve the LLS function.The two stops 5 and 6 and the blocking element 3 are then positioned in reverse order at the end position of the blocked belt shaft body 12, i.e., the second stop 5 is located upstream of the blocking element 3 with respect to the preceding rotational movement of the belt shaft body 12, and the first stop 6 is located downstream with respect to the blocking element 3. In other words, the first stop 6 is located upstream of the blocking element 3 with respect to the stopped rotational movement of the belt shaft body 12, and the second stop 5 is located downstream.

[0029] The proposed solution makes it possible to implement a force-limited webbing extension movement with a mechanical stop for one rotation of the webbing shaft body 12 from more than 360 degrees up to almost 720 degrees. The maximum possible force-limited webbing extension length can be more precisely determined by the width of the stops 5 and 6 and the blocking element 3.

[0030] As in the Fig. As can be seen in Figure 2, the first stop 6 on the belt shaft body 12 has a circumferential angle of 45 degrees, while the second stop 5 on the profile head 2 has a circumferential angle of 60 degrees. The blocking element 3 has a circumferential angle of 30 degrees. The angles of the stops 5 and 6 and of the blocking element 3 can alternatively be considered as the angles between the stop surfaces 14, 15, 16 and 17, or between the end faces 18 and 19.

[0031] In the Fig. From the initial position 3, a total angle of 135 degrees results between the stop surface 16 of the first stop 6 and the stop surface 15 of the second stop 5, formed by the assembly of the two stops 5 and 6 with the blocking element 3 arranged between them. This results in a maximum force-limited rotation angle of the belt shaft body 12 relative to the profile head 2 of 585 degrees, namely the angle of 720 degrees of two revolutions minus the total angle of 135 degrees until the stops 5 and 6 and the blocking element 3, starting from the initial position of the Fig. 3 are blocked in reverse order. Depending on the dimensioning of the angles of the stops 5 and 6 and the blocking part 3, different maximum force-limited rotation angles of the belt shaft body 12 relative to the blocked profile head 2 can be achieved.

[0032] The belt shaft body 12 is preferably made of aluminum using a die-casting process, e.g., of material A380. The profile head 2 is preferably made of a zinc alloy ZnAl4Cu1 (also known as Zamak), also using a die-casting process. The blocking element 3 is made of a steel of type D39 or ML08A1 with a zinc coating and exhibits a higher deformation strength than the profile head 2 and the belt shaft body 12. The deformation strength of the blocking element 3 is preferably high enough to withstand a torque of 180 Nm exerted by the belt shaft body 12 without being destroyed. 1 belt shaft 2 Profile head 3 Blocking part 4 guide grooves 5 Second attack 6 First attack 7 Ring process 8 Ring wall 9 Ring wall 10 Profile recess 11 Force limiting device 12 belt shaft bodies 13 Profile recess 14 Stop surface 15 Stop surface 16 Stop surface 17 Stop surface 18 Front 19 Front 20 drive wheel 21 spring cassette 22 frames 23 penalty box 24 sensor housings 25 Cover QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 409 882 A1

[0005] DE 10 2018 106 664 B4

[0006]

Claims

[1] Self-locking belt retractor for a seat belt system of a motor vehicle with -a two-part belt shaft (1) with a belt shaft body (12) and a profile head (2), and -a blocking device with a blocking pawl mounted on the profile head (2), which, when activated, engages in a vehicle-fixed toothing in a blocked position to block the profile head (2) in the belt extension direction, and -a force limiting device (11) arranged in the force transmission path between the belt shaft body (12) and the profile head (2), which, in the event of a blocked profile head (2), enables a rotational movement of the belt shaft body (12) towards the blocked profile head (2) in the belt extension direction by its activation, characterized by , that -a first stop (6) is provided on the belt shaft body (12), and -a second stop (5) is provided on the profile head (2), and -a blocking part (3) is provided which, during a rotational movement of the belt shaft body (12) in the belt extension direction during the activation of the force limiting device (11), comes into contact with the second stop (5) of the profile head (2), wherein -the blocking part (3) in the blocking assembly at the second stop (5) limits the rotational movement of the belt shaft body (12) by a blocking engagement of the first stop (6) of the belt shaft body (12) at the blocking part (3). [2] Self-locking seatbelt retractor according to claim 1, characterized by , that -an annular guide groove (4) is provided on the belt shaft body (12), which is interrupted by the first stop (6), wherein -the blocking part (3) engages with a first section in the guide groove (4) and projects with a second section beyond the guide groove (4) and extends into the plane perpendicular to the axis of rotation of the belt shaft body (12), in which the second stop (5) of the profile head (2) is arranged. [3] Self-locking seatbelt retractor according to claim 2, characterized by , that -the blocking part (3) is fixed in position in the guide groove (4) by a shear pin (8). [4] Self-locking seatbelt retractor according to one of claims 2 or 3, characterized by , that -the blocking part (3) has at least in the first section a radial extension which corresponds to the radial extension of the guide groove (4). [5] Self-locking belt retractor according to any one of claims 1 to 4, characterized by , that -the first stop (6), the second stop (5) and the blocking part (3) are arranged on an identical radius in relation to the axis of rotation of the belt shaft body (12). [6] Self-locking seatbelt retractor according to any one of claims 1 to 5, characterized by , that -the blocking part (3) is arranged at the beginning of the rotational movement of the belt shaft body (12) to the profile head (2) between the first and the second stop (6,5). [7] Self-locking belt retractor according to claim 6, characterized by , that -the blocking part (3) is arranged in relation to the rotational movement of the belt shaft body (12) upstream in the belt extension direction in a system at the first stop (6). [8] Self-locking seatbelt retractor according to any one of claims 1 to 7, characterized by , that -the first stop (6) and the second stop (5) each have two lateral stop surfaces (14, 15, 16, 17) extending radially through the axis of rotation of the belt shaft body (12) and the blocking part (3) is formed by a ring segment with radially directed end faces (18, 19) extending through the axis of rotation of the belt shaft body (12). [9] Self-locking belt retractor according to any one of claims 1 to 8, characterized by , that -the blocking part (3) has a higher deformation strength than the profile head (2) and the belt shaft body (12).

Images