Belt retractor for automotive seat belt systems

Abstract

The present invention relates to a belt retractor (1) for an automobile seat belt device, comprising a belt reel (5) capable of winding up a seat belt of the seat belt device, a reversible belt tensioner (3) having a drive wheel (20) that, when in operation, drives the belt reel (5) in the winding direction via the drive wheel (20), and a forcibly controlled tensioner coupling (2) that transmits driving motion from the drive wheel (20) to the belt reel (5), wherein the tensioner coupling (2) has at least one coupling claw (21) mounted on the drive wheel (20) which is movable to engage and disengage with a tooth system (231) fixed on the belt reel in order to generate and disengage rotational coupling of the drive wheel (20). The coupling claw (21) has a body (212) having a tooth system portion (213), and having a greater width in the region of the tooth system portion (213) perpendicular to the direction of engagement movement than in the region of the body (212).

Description

Technical Field

[0001] The present invention relates to a belt retractor for an automobile seat belt device having the features of the preamble of claim 1.

Background Art

[0002] A belt retractor is used in an automobile seat belt device and functions to wind up one end of a seat belt provided to restrain an occupant. The belt retractor is fastened to any one of a vehicle structure, a vehicle seat fastened to the vehicle structure, or a bench seat fastened to the vehicle structure. In its basic structure, the belt retractor has a frame provided for the purpose of fastening and a belt reel rotatably mounted within the frame, and the seat belt can be wound up on the belt reel. The belt reel is spring-biased in the winding direction via a spring and, when a predetermined belt pull-out acceleration or vehicle deceleration is exceeded, can be blocked by a blocking device against further pull-out of the seat belt so that the occupant is restrained before colliding with the vehicle interior structure to prevent serious injury.

[0003] In order to reduce the occupant load during restraint, it has been proven advantageous to have a force-limiting device that enables force-limited rotation of the belt reel in the pull-out direction and, thus, force-limited forward displacement of the occupant when the blocked belt reel and a predetermined belt pull-out force are exceeded. Since the reduction of the occupant load enabled by the force-limiting device is directly related to the available forward displacement path, it has further been found advantageous to wind up the slack of the belt present in the seat belt by a belt tensioner before the operation of the force-limiting device in order to increase the available forward displacement path and couple the occupant to the vehicle deceleration as early as possible.

[0004] In belt tensioners, there is a distinction between reversible belt tensioners, irreversible belt tensioners, and even performance tensioners. Reversible belt tensioners have a lower tension adjustment capacity of approximately 100-800N and function to tighten the belt in dangerous situations in preparation for a potential subsequent accident. If no accident occurs, the seat belt is loosened again. Electric motors that can be controlled particularly well and reversibly have proven effective for driving reversible belt tensioners. Irreversible belt tensioners have a higher tension adjustment capacity of 400-2000N and are activated only when an accident is no longer avoidable, i.e., in the initial stages of an accident. Therefore, irreversible belt tensioners are always activated after reversible belt tensioners. Since explosive-type drive devices that cannot be activated again after being activated have proven to be effective as drive devices for irreversible belt tensioners, in this case, the entire seat belt system with an irreversible belt tensioner must be replaced.

[0005] In this case, the belt tensioner may engage at different locations on the seat belt, for example, at the belt buckle, end fitting, or even at the belt retractor. When the belt tensioner is used in the belt retractor, it abruptly drives the belt reel in the winding direction when in operation, thereby winding up any slack in the seat belt. For the purposes of this invention, the term “belt tensioner” should be understood to mean only those belt tensioners that are located on the belt retractor and drive the belt reel. Since the belt reel must, in principle, be able to rotate freely for seat belt fastening and unfastening in normal use, the drives for both reversible and irreversible belt tensioners are connected to the belt reel via couplings only when in operation. The couplings should be designed so as not to unintentionally establish a rotational connection, and for this reason, in the normal use of the belt retractor, this is hindered due to the resulting obstruction of the rotational movement of the belt reel.

[0006] The reversible belt tensioner will deactivate again if no further accidents occur and the belt retractor can be used normally again; therefore, the coupling of the reversible belt tensioner must also be of a similarly reversible design. Furthermore, the coupling of the reversible belt tensioner must be intentionally disengaged in the event of a subsequent accident and activation of the irreversible belt tensioner, so as not to interfere with the driving motion of the irreversible belt tensioner by the still-engaged coupling of the reversible belt tensioner.

[0007] Furthermore, the coupling of various belt tensioners must be designed to automatically establish a rotational connection between the drive unit and the belt reel when the drive unit is activated, which can be achieved, for example, by friction, by inertial force, or by a control profile. In this way, the motion of the coupling is forcibly controlled by the start of the drive unit's motion.

[0008] Therefore, the coupling needs to perform coupling motion automatically when the drive mechanism is activated, but intentionally refrain from performing coupling motion in other situations to prevent unwanted coupling connections.

[0009] For example, a belt retractor having a reversible belt tensioner with a friction-controlled coupling comprising two coupling claws and a brake element is known from the applicant's German Patent No. 10059227(C1). The coupling claws are slidably mounted on the drive wheel and engage with the inner teeth of a coupling bell connected in a manner that is non-rotatably fixed to the belt shaft in order to establish a coupling connection.

[0010] A coupling for a belt tensioner is also known from German Patent No. 102014009038(B4), which has two coupling claws mounted on a drive wheel, referred to as input elements, the coupling claws engaging with the outer teeth of an output element connected to a belt reel to establish a coupling connection. A control element coupled to an inertial mass is provided to control the motion of the coupling elements, and this control element is provided with an input control shape and an output control shape for controlling the motion of the coupling claws.

[0011] In both exemplary embodiments, each coupling claw has a body having a toothed system portion, the teeth being provided on the toothed system portion that engage with the outer teeth of the coupling bell or output element.

[0012] One problem with such belt retractors having a reversible belt tensioner is that a relatively large number of cooperating parts are provided, which inevitably leads to correspondingly high installation space requirements, and that the parts must work together with process reliability so that the coupling and uncoupling operations of the reversible belt tensioner can be performed safely. [Overview of the project]

[0013] Against this backdrop, the object of the present invention is to provide a belt retractor having a reversible belt tensioner and a coupling with coupling claws, which should have a compact design and at the same time have process-reliable engagement of the coupling claws within a tooth system fixed on a belt reel.

[0014] To achieve the objective, a seat belt retractor having the features of claim 1 is proposed. Further preferred embodiments of the present invention can be gathered from the dependent claims, figures, and related description.

[0015] According to the basic concept of the present invention, it is proposed that the connecting claw has a greater width than the main body region in the region of the tooth system portion perpendicular to the direction of engagement movement.

[0016] The proposed solution has several advantages. On the one hand, tooth engagement is performed with a lower local load on the coupling claw in the region of the tooth system portion, and at the same time, the coupling claw is configured to narrow in the region of the body so that it requires less installation space and can therefore be placed in a narrower annular space. Furthermore, the load-bearing capacity of the coupling claw in the region of the tooth system is increased, and therefore the possibility of plastic deformation of the coupling claw during tooth engagement is reduced. Moreover, the coupling engagement is performed with improved process reliability due to the increased overlap caused by the thickened portion. The width is intentionally increased perpendicular to the direction of engagement motion because this defines the engagement surface of the tooth system portion on the teeth fixed on the belt reel.

[0017] It is further proposed that the coupling claw has a width perpendicular to the direction of engagement movement, either larger than or equal to the teeth fixed to the belt reel, in the region of the tooth system portion. This allows for a tooth system fixed to the narrowest possible belt reel with the smallest possible installation space, and the coupling claw, with its increased width, is utilized to the maximum extent for torque transmission in any case.

[0018] It is further proposed that the coupling claw has a flat surface on one side, and that a greater thickness in the region of the tooth system portion is achieved by a thickened portion on one side of the opposite side of the coupling claw. The flat surface on one side allows for improved guidance of the coupling claw during coupling motion by enabling the coupling claw to contact the opposing surface of the reversible belt tensioner over the largest possible surface area via the flat surface on the side.

[0019] It is further proposed that the coupling claw has a first bearing pin, the first bearing pin protruding from the thickened side of the coupling claw, and the coupling claw is attached to the thickened side via the first bearing pin. Due to the thickened side on one side, the point of application of force in the tooth system of the coupling claw is shifted laterally from the center, and therefore, in extreme cases, an inclination moment acts on the coupling claw. To absorb these inclination moments when attaching the coupling claw, the first bearing pin protrudes from the same side of the thickened side, and the coupling claw is attached via the first bearing pin corresponding to this side of the reversible belt tensioner.

[0020] It is further proposed that a second bearing pin is positioned upstream of the tooth system portion with respect to the direction of rotation of the drive wheel, and that the teeth of the tooth system portion are oriented toward the second bearing pin. The drive wheel supports the coupling pawl via the second bearing pin, and the drive torque is further transmitted from the coupling pawl through the tooth system portion to the teeth fixed on the belt reel. For this purpose, the teeth of the tooth system portion of the coupling pawl are preferably oriented toward the second bearing pin.

[0021] It is further proposed that the drive wheel and / or the cover plate covering the drive wheel have a recess in which the coupling claw engages with the thickened tooth system portion. This means that the coupling claw itself, having its narrow body, can be positioned within the corresponding narrow installation space of the belt retractor, and the recess generates the necessary free space for the thickened portion of the tooth system.

[0022] It is further proposed that the wider width of the tooth system portion corresponds to 1.1 to 1.3 times the width of the connecting claw in the main body region. This increases the contact surface area of ​​the tooth system portion on the teeth fixed on the belt reel by 1.1 to 1.3 times.

[0023] It is further proposed that the coupling claw has an arc shape and the tooth system part is arranged on the inner side in the radial direction of the coupling claw. Therefore, the coupling claw has a tooth system fixed on the belt reel on the outer side in the radial direction, and engages with the teeth fixed on the belt reel on the inner side in the radial direction thereof.

[0024] Hereinafter, the present invention will be described using preferred embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] A belt retractor according to the present invention having a reversible belt tensioner. [Figure 2] A coupling claw for coupling a belt retractor as a single part. [Figure 3] A perspective view of a housing part of a reversible belt tensioner provided with a coupling claw, a cover plate, and a toothed ring. [Figure 4] A cross-sectional view of the housing part of FIG. 5 in the cross-sectional direction A-A. [Figure 5] A housing part having a coupling claw and a toothed ring as viewed from above the cover plate and the toothed ring.

Embodiments for Carrying Out the Invention

[0026] FIG. 1 shows a belt retractor 1 according to the present invention having a reversible belt tensioner 3, a drive wheel 20, a tensioner coupling 2, and a take-up unit 4. In an exemplary embodiment of the present invention, the take-up unit 4 includes, as basic components, a belt reel 5 rotatably attached to a frame 6 having an axially extending portion 8, and an irreversible pyrotechnic belt tensioner 7 or a power tensioner. However, it is also conceivable to provide a take-up unit 4 that does not include a power tensioner and includes only the reversible belt tensioner 3.

[0027] The reversible belt tensioner 3 operates in pre-accident conditions and functions to tighten the seat belt in preparation for a potential accident. The seat belt is tightened with a tension of 100-800N, and the tension adjustment force can be selected to various levels according to the vehicle manufacturer's specifications, or the tension adjustment force can be designed to increase in stages according to various specific pre-accident criteria.

[0028] The irreversible belt tensioner 7 activates only when an accident is no longer avoidable or has begun, causing a greater increase in seat belt tension of 400-2000N compared to the tension increase when the reversible belt tensioner 3 is activated. Therefore, when the irreversible belt tensioner 7 is activated, the belt reel 5 is driven with considerably greater torque and higher rotational acceleration than when the reversible belt tensioner 3 is activated.

[0029] The reversible belt tensioner 3 comprises an electric motor and a gearbox with an internal gear mechanism that transfers the rotational drive motion of the electric motor to the drive wheel 20.

[0030] On the extended portion 8 of the belt reel 5, a toothed ring 23, as shown in Figure 2, is held in a non-rotatable state via the overload ring 26 until a torque defined by the overload ring 26 is reached. The toothed ring 23 has radially outward teeth that form a fixed toothed portion 231 on the belt reel at the fastening position of the toothed ring 23 on the extended portion 8.

[0031] The housing portion 25 is mounted on the gearbox of the reversible belt tensioner 3, and the drive wheel 20 is rotatably mounted therein. For this purpose, the housing portion 25 has an annular axial extension that penetrates the central bearing opening of the drive wheel 20. Furthermore, a control element 22 is provided which is fixed by friction to the axial extension. In addition, a coupling claw 21 is provided, which is arc-shaped and has a first bearing pin 211 and a second bearing pin 215 protruding from one end. Furthermore, an annular cover plate 24 is provided which has a bearing opening 241 as can be seen in Figure 3, where the coupling claw 21 is attached by the first bearing pin 211, and the second bearing pin 215 engages with the bearing opening (not visible) of the drive wheel 20. Thus, the coupling claw 21 is attached to both sides inside the drive wheel 20 and on the cover plate 24 via the first bearing pin 211 and the second bearing pin 215. The engagement movement of the coupling pawl 21 is forcibly controlled by the control element 22 when the reversible belt tensioner 3 is activated. In this case, the coupling pawl 21 is forced to perform a pivoting motion oriented radially inward, during which it engages with its tooth system portion 213 on the teeth 231 fixed on the belt reel.

[0032] Figure 2 shows the coupling claw 21 enlarged as a single component. The coupling claw 21 is curved in an arc shape and has a tooth system portion 213 at one end radially inward. The coupling claw 21 has a first bearing pin 211 projecting axially at the other end and a second bearing pin 215 projecting axially on the opposite side. The coupling claw 21 has a narrow body 212 and is thickened in the region of the tooth system portion 213 by a thickened portion 214 on one side, increasing its width by 1.1 to 1.3 times compared to the body 212. The teeth of the tooth system portion 213 are aligned so that the teeth are oriented toward the bearing pin 211.

[0033] In Figure 3, the housing portion 25, which has a cover plate 24, coupling claws 21, and a toothed ring 23, can be seen without the drive wheel 20, the extension portion 8, and the overload ring 26 positioned between them. The cover plate 24 has a recess 242 that is dimensioned and positioned so that the coupling claws 21 engage with the thickened portion 214 therein. Thus, despite the thickened portion 214, the coupling claws 21, together with their narrow body 212, can be positioned within the corresponding narrow mounting space between the cover plate 24 and the drive wheel 20 (not shown).

[0034] Figure 5 shows the housing portion 25, which has the cover plate 24, coupling claws 21, and toothed ring 23 of Figure 3, as viewed from above the cover plate 24, while Figure 4 shows a cross-section in the cross-sectional direction AA of Figure 5. The coupling claws 21 are positioned such that the first bearing pin 211 and the second bearing pin 215 are located upstream of the toothed system portion 213 in the direction of the drive rotation of the drive wheel 20 (not shown), in this case clockwise. Furthermore, the teeth of the toothed system portion 213 are aligned in the direction of the first bearing pin 211 and the second bearing pin 215, and as a result the coupling claws 21 are pulled clockwise from the first bearing pin 211 and the second bearing pin 215, thereby transmitting torque from the toothed system portion 213 to the belt reel 5 via the teeth 231 and overload ring 26 fixed on the belt reel in order to pretension the seat belt.

[0035] In the cross-sectional view of Figure 4, it can be seen that the coupling claw 21 has a wide overlap with the teeth 231 fixed on the belt reel due to the thickened portion 214 on one side within the region of the tooth system portion 213, thereby reducing local material stress and simultaneously making the engagement of the teeth more reliable. The coupling claw 21 has a flat surface on its non-thickened surface, i.e., the right-hand surface in the display of Figure 4, so that the installation space requirements of the coupling claw 21 on this side are optimized and reduced, and the coupling claw 21 can be positioned within the corresponding narrow plate-shaped installation space in the belt retractor.

[0036] The first bearing pin 211 engages with the bearing opening 241 of the cover plate 24 on one side, so that the coupling claw 21 is mounted on the same side where the thickened portion 214 extends outward. If inclination moments act on the coupling claw 21 as a result of the tooth system portion 213 widening on one side, these are absorbed by mounting the coupling claw 21 via the first bearing pin 211 engaging with the bearing opening 241 on the same side, so that the coupling claw 21 is held in as nearly planar contact as possible with the teeth 231 fixed on the belt reel at its tooth system portion 213. Since the coupling claw 21 is also mounted in the drive wheel 20 at the same time as the second bearing pin 215, the coupling claw 21 is additionally mounted on the other side to counteract the acting inclination moments. Therefore, the coupling claw 21 is attached to both sides of the bearing opening 241 in the cover plate 24 and the bearing opening in the drive wheel 20 via the first bearing pin 211 and the second bearing pin 215.

[0037] The first bearing pin 211 and the second bearing pin 215 are preferably formed integrally with the coupling claw 21. Alternatively, the first bearing pin 211 and the second bearing pin 215 may be formed by a single bearing pin protruding through the coupling claw 21.

Claims

1. A belt retractor (1) for a seat belt system of an automobile, - A rotatably mounted belt reel (5) capable of winding up the seat belt of the seat belt device, - A reversible belt tensioner (3) having a drive wheel (20), which, when in operation, drives the belt reel (5) in the winding direction via the drive wheel (20), - A forcibly controlled tensioner coupling (2) that transmits driving motion from the drive wheel (20) to the belt reel (5), wherein the tensioner coupling (2) is - At least one coupling pawl (21) mounted on the drive wheel (20) is movable to engage and disengage with a tooth system (231) fixed on the belt reel in order to generate and disengage rotational coupling of the drive wheel (20), - The coupling claw (21) has a body (212) having a tooth system portion (213), and a tensioner coupling (2) having a coupling claw (21), - A belt retractor (1) characterized in that the connecting claw (21) has a greater width than the area of ​​the main body (212) in the region of the tooth system portion (213) perpendicular to the direction of engagement movement.

2. - The belt retractor (1) according to claim 1, characterized in that the coupling claw (21) has a width perpendicular to the direction of engagement movement, which is larger than or the same as the teeth (231) fixed on the belt reel, in the region of the tooth system portion (213).

3. - The belt retractor (1) according to claim 1 or 2, characterized in that the coupling claw (21) has a flat surface on one side, and the greater thickness in the region of the tooth system portion (213) is achieved by a thickened portion (214) on one side of the opposite side of the coupling claw (21).

4. - The connecting claw (21) has a first bearing pin (211), - The first bearing pin (211) protrudes from the side of the thickened portion (214) of the coupling claw (21), - The belt retractor (1) according to claim 3, characterized in that the coupling claw (21) is attached to the side of the thickened portion (214) via the first bearing pin (211).

5. - The second bearing pin (215) is positioned upstream of the tooth system portion (213) with respect to the direction of rotation of the drive wheel (20). - The belt retractor (1) according to any one of claims 1 to 4, characterized in that the teeth of the tooth system portion (213) are oriented toward the second bearing pin (215).

6. - The belt retractor (1) according to any one of claims 1 to 5, characterized in that the drive wheel (20) and / or the cover plate (24) covering the drive wheel (20) has a recess (242) in which the coupling claw (21) engages with the thick-walled tooth system portion (213).

7. - The belt retractor (1) according to any one of claims 1 to 6, characterized in that the larger width of the tooth system portion (213) corresponds to 1.1 to 1.3 times the width of the connecting claw (21) in the region of the main body (212).

8. The connecting claw (21) has an arc shape, The belt retractor (1) according to any one of claims 1 to 7, characterized in that the tooth system portion (213) is arranged radially inward of the coupling claw (21).

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