Belt retractor for a seat belt system of a motor vehicle

Abstract

To reliably prevent undesired engagement movement of a coupling claw after reversible belt tightening during irreversible belt tightening. The belt retractor (1) comprises a belt reel (5), a reversible belt tensioner having a drive wheel (20) and driving the belt reel (5) in a retracting direction, a coupling pawl (21) engaging and disengaging with a belt reel tooth (231) to establish and release a rotational connection of the drive wheel (20), and a control element (22) having a first control contour (223) for controlling the engagement movement of the coupling pawl (21). A first control pin (212) is provided on the coupling pawl (21) sliding along the first control contour (223), the first control contour (223) being fixed to the control element (22) and formed by a spring arm (228), and the first control pin (212) sliding from a fixed end to a free end during the engagement movement of the coupling pawl (21).

Description

[Technical Field]

[0001] The invention relates to a belt retractor for a seat belt system of a motor vehicle having the features of the preamble of claim 1. [Background technology]

[0002] A belt retractor is used in a seat belt system of an automobile and functions to retract one end of a seat belt provided to restrain an occupant. The belt retractor is fastened to either the 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 fastening purposes and a belt reel rotatably mounted in the frame, and the seat belt can be retracted onto the belt reel. The belt reel is spring-loaded in the retracting direction via a spring, and when a predetermined belt retraction acceleration or vehicle deceleration is exceeded, further retraction of the seat belt can be blocked by a blocking device, so that the occupant is restrained before colliding with the vehicle interior structure to prevent serious injury.

[0003] In order to reduce the load on the occupant during restraint, a force limiting device has proven advantageous, which allows a force-limited rotation of the belt reel in the unwinding direction when the belt reel is blocked and exceeds a predetermined belt unwinding force, and thus a force-limited forward displacement of the occupant.Since the reduction in occupant load allowed by the force limiting device is directly related to the available forward displacement path, it has further been found advantageous to take up the belt slack present in the seat belt by means of a belt tensioner before activation of the force limiting device, in order to increase the available forward displacement path and thus couple the occupant to the vehicle deceleration as early as possible.

[0004] Belt tensioners are distinguished between reversible and irreversible or even performance tensioners. Reversible belt tensioners have a lower tensioning capacity of approximately 100-800 N and function to retract slack in dangerous situations in preparation for a potential subsequent accident. If no accident occurs, the seat belt is then loosened again. Electric motors that can be particularly well and reversibly controlled have proven effective for driving reversible belt tensioners. Irreversible belt tensioners have a higher tensioning capacity of 400-2000 N and are only activated when an accident can no longer be avoided, i.e., in the early stages of an accident. Therefore, irreversible belt tensioners are always activated after reversible belt tensioners. Pyrotechnic drives, which cannot be reactivated after activation, have proven to be effective as drives for irreversible belt tensioners. In this case, the entire seat belt system with the irreversible belt tensioner must be replaced.

[0005] In this case, the belt tensioner can engage at different positions of the seat belt, for example, at the belt buckle, the end attachment, or even at the belt retractor. When the belt tensioner is used in the belt retractor, it drives the belt reel sharply in the retracting direction when activated, thereby retracting any existing belt slack in the seat belt. For the purposes of the present invention, the term "belt tensioner" should be understood to mean only those belt tensioners that are arranged on the belt retractor and drive the belt reel. Since the belt reel must basically be able to rotate freely in normal use for fastening and unfastening the seat belt, the drives of both reversible and also irreversible belt tensioners are connected to the belt reel via a coupling only in the event of activation. The coupling should be designed so that a rotational connection is never unintentionally established, so that normal use of the belt retractor is hindered due to the resulting blockage of the rotational movement of the belt reel.

[0006] The coupling of the reversible belt tensioner must also be of a reversible design, since it can be deactivated again if the accident does not subsequently occur and the belt retractor can again be used normally. Furthermore, the coupling of the reversible belt tensioner must then also be intentionally disengaged so that when an accident subsequently occurs and the irreversible belt tensioner is activated, the drive movement of the irreversible belt tensioner is not hindered 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 and the belt reel when the drive is activated, which can be achieved, for example, by friction, by inertia, or by a control profile, which ensures that the movement of the coupling is controlled by the initiation of the movement of the drive.

[0008] Therefore, the coupling is required to, on the one hand, automatically perform the coupling movement when the drive is activated, but to intentionally not perform the coupling movement in other situations in order to prevent undesired coupling connections.

[0009] For example, a belt retractor having a reversible belt tensioner with two coupling pawls and a friction-controlled coupling with a brake element is known from the applicant's document DE 100 59 227 (C1). The coupling pawls are slidably mounted on the drive wheel and engage with the inner toothing of a clutch bell connected in a rotatably fixed manner to the belt shaft to establish the coupling connection.

[0010] A coupling for a belt tensioner is also known from German Patent No. 102014009038 (B4), which has two coupling pawls mounted on a drive wheel, called input element, which engage with the outer toothing of an output element connected to a belt reel to establish a coupling connection. To control the movement of the coupling element, a control element is provided which is connected to an inertial mass and which is provided with an input control geometry and an output control geometry for controlling the movement of the coupling pawls. Summary of the Invention

[0011] Against this background, the invention is based on the object of providing a belt retractor of the general type in which undesired engagement movements of the coupling pawls after reversible belt tightening have taken place are reliably prevented during irreversible belt tightening.

[0012] To achieve the object, a seat belt retractor is proposed having the features of claim 1. Further preferred embodiments of the invention can be gleaned from the dependent claims, the figures and the associated description.

[0013] According to the basic idea of ​​the invention, a first control pin is provided on the coupling claw, by means of which the coupling pin slides on a first control contour during the engagement movement, the first control contour is formed by a spring arm fixed at one end to the control element, the first control pin slides on the spring arm from the fixed end to the free end during the engagement movement of the coupling pawl; - the coupling pawls are forced radially outward in the winding direction in the event of a rotational movement of the teeth fixed on the belt reel, - through the compressive force exerted by the first control pin on the spring arm by its force, the control elements are forced to perform a relative movement, while the second control pin of one of the coupling claws slides on the second block face, It is proposed that the second blocking surface blocks the coupling pawl against a pivoting movement directed radially inwards towards the toothing fixed on the belt reel.

[0014] The coupling pawl rests on a first control profile together with a first control pin, which, via its shape, defines the path of the coupling pawl's engagement movement on the toothing fixed on the belt reel by the first control pin sliding thereon. Designing the first control profile as a spring arm and its proposed arrangement allow the control pin and the coupling pawl to perform a slight radial movement relative to the first control profile during the engagement movement. This prevents the movement from being hindered due to geometric inaccuracies or differences in frictional forces. The proposed solution means that when the irreversible belt tensioner is activated and the belt reel rotates in the reeling direction, the coupling pawl is automatically pushed out of the engagement position and the coupling connection is released. Additionally, the coupling pawl is simultaneously blocked by a support on a second blocking surface against repeated engagement movements on the toothing fixed on the belt reel.

[0015] It is further proposed that a radially extending force transmission surface is provided on the drive wheel, which force transmission surface is arranged in such a way that the coupling pawl rests thereon together with the end face contact surface as a result of the engagement movement into the toothing, and the drive wheel drives the coupling pawl in the engagement position onto the toothing fixed on the belt reel, while exerting a compressive force in the circumferential direction of the drive wheel, so as to transmit a rotational movement onto the belt reel via the force transmission surface.

[0016] Due to the radially extending force transmission surfaces provided on the drive wheel and the drive of the coupling pawls realized above them, the drive force is transmitted to the belt reel by the engagement of the coupling pawls with the teeth that are rotatably and fixedly connected to the belt reel, and the drive force is transmitted more quickly and therefore more directly from the drive wheel to the coupling pawls and the belt reel. In so doing, the bearing forces that must be absorbed by the coupling pawls on the drive wheel in the rotary joint are simultaneously reduced by dividing the bearing forces between the rotary joint and the radially extending force transmission surfaces. Ideally, the drive torque can be transmitted without bearing loads on the coupling pawls by arranging the rotary joint so that it is located outside the force transmission path from the force transmission surfaces via the coupling pawls to the teeth that are fixedly arranged on the belt reel.

[0017] Furthermore, it is proposed that the force transmission surfaces have a radial inclination relative to the rotation axis of the drive wheel, this inclination being aligned with the teeth of the toothing fixed on the belt reel. Due to the proposed alignment of the force transmission surfaces in relation to the alignment of the teeth of the toothing fixed on the belt reel, the teeth form coaxial reaction surfaces for transmitting forces, so that the force vectors are also coaxial during force transmission from the drive wheel to the coupling pawl and from the coupling pawl to the toothing fixed on the belt reel. This makes it possible to optimize the force transmission conditions, in particular with regard to avoiding slippage of the force transmission surfaces as much as possible.

[0018] Furthermore, it is proposed that the force transmission surface is arranged so that the coupling pawl resting thereon is arranged without contact with the first control contour. This means that the first control contour is not subjected to load during the drive of the belt reel during reversible belt tensioning. This also ensures that force transmission takes place exclusively via the force transmission surface of the drive wheel, the end face contact surface of the coupling pawl and the bearing of the coupling pawl at the rotary joint.

[0019] It is further proposed that the at least one first tooth is provided on the coupling claw, which in the engagement position engages with the at least one first tooth on the toothing fixed on the belt reel, so that the coupling claw has a contour adapted to the toothing fixed on the belt reel, and the toothing shape of the at least one first tooth on the toothing surface corresponds to the toothing surface of the toothing fixed on the belt reel.

[0020] Furthermore, it is proposed that the end faces of the teeth facing the toothing part fixed on the belt reel are aligned in such a way that the angle between the end faces of the teeth and the radially outwardly directed end faces of the teeth of the toothing part is less than 30 degrees. Due to the proposed alignment of the end faces of the teeth with the end faces of the teeth of the toothing part fixed on the belt reel, in case of tooth-to-tooth contact, the tooth slides off the tooth of the toothing part fixed on the belt reel with very low compressive force and without jamming itself.

[0021] It is further proposed that at least one second tooth is provided, the first or second tooth being designed to form an enlarged receiving tooth with which the coupling pawl first engages during the engagement movement at the toothing fixed on the belt reel, the enlarged receiving tooth first engaging with the toothing fixed on the belt reel, thereby bringing about a pre-alignment of the coupling pawl with the toothing fixed on the belt reel, so that the further tooth then engages with the toothing fixed on the belt reel in a defined alignment without becoming blocked itself in case of tooth-to-tooth contact.

[0022] In this case, the receiving tooth is preferably formed by the first tooth adjacent to the end contact surface, so that the coupling claw is pulled into the toothing fixed on the belt reel starting from the end facing the end contact surface.

[0023] It is further proposed that the first control contour has a blocking portion aligned in the circumferential direction, and that the first control pin is arranged on the coupling pawl in such a way that in the engagement position of the coupling pawl it is arranged radially inward relative to the blocking portion, Due to the blocking portion of the first control contour, the coupling pawl is blocked against a radially outward directed control movement from the toothing fixed on the belt reel during toothing engagement during reversible pretensioning.

[0024] It is further proposed that a second control contour is provided on the control element for controlling the disengagement movement of the coupling pawl, which second control contour controls the disengagement movement of the coupling pawl in the process independently of the engagement movement of the coupling pawl, depending on the respective shape of the second control contour.

[0025] In this case, preferably, a second control pin can be provided on the coupling pawl, by means of which second control pin the coupling pin slides on a second control contour during the disengagement movement.

[0026] It is further proposed that a blocking contour be provided on the control element, which forms a stop for the coupling pawl in the engagement position. The blocking contour defines the end position of the coupling pawl after completion of the engagement movement, and further limits any further differential movement of the control contour relative to the coupling pawl.

[0027] It is further proposed that the block contour has a radially aligned first block face and a circumferentially aligned second block face, the first block face forming a stop.

[0028] It is further proposed that the coupling claw has a curved, arcuate shape and is arranged so that its curved, shorter side faces the toothing fixed on the belt reel. The curved coupling claw thus engages around the toothing fixed on the belt reel and forms with its curved, shorter side or also on the inside of the force transmission surface. For this purpose, the inside force transmission surface can be provided with, for example, one or more teeth.

[0029] Furthermore, in this regard, it is proposed that the coupling pawl is pivotally mounted on a pivot bearing, which is arranged on an end of the coupling pawl that is further away from the end face contact surface, during the pivoting movement the coupling pawl pivots radially inwards together with the end face contact surface and thereby comes into contact with the force transmission surface of the drive wheel by means of the contact surface. [Brief explanation of the drawings]

[0030] The present invention will be described below using preferred embodiments with reference to the accompanying drawings, in which: [Figure 1] 1 is a belt retractor according to the present invention having a reversible belt tensioner. [Figure 2] A drive wheel having a tensioner coupling and a housing portion for transmitting the rotational motion of a reversible belt tensioner. [Figure 3] A drive wheel, a coupling pawl, and teeth fixed on the belt reel during the engagement movement. [Figure 4] A drive wheel, a coupling pawl, and teeth fixed to the belt reel in a disengaged position. [Figure 5] A drive wheel, a coupling pawl, and teeth fixed to the belt reel in the engaged position. [Figure 6] A drive wheel, a coupling pawl, and a tooth portion fixed to the belt reel in a first contact position during the engagement movement. [Figure 7] A drive wheel, a coupling pawl and a tooth portion fixed on the belt reel at the tooth-to-tooth contact position of the first tooth during the engagement movement. [Figure 8] 1 is an enlarged view of the drive wheel, coupling pawl and toothing fixed to the belt reel at the tooth-to-tooth contact position of the first tooth during the engagement movement. FIG. [Figure 9] 1 shows a drive wheel, coupling pawl, and teeth fixed to a belt reel in different positions during operation of an irreversible belt tensioner. DETAILED DESCRIPTION OF THE INVENTION

[0031] 1 shows a belt retractor 1 according to the invention, which comprises a reversible belt tensioner 3, a drive wheel 20, a tensioner coupling 2 and a winding unit 4. The winding unit 4 comprises as its basic components a belt reel 5 rotatably mounted on a frame 6 having an axial extension 8, and an irreversible pyrotechnic belt tensioner 7 or power tensioner.

[0032] The reversible belt tensioner 3 operates in pre-accident situations to tighten the seat belt in preparation for a possible accident. The seat belt is tightened with a tension of 100 to 800 N, and the tension adjustment force can be selected at 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.

[0033] The irreversible belt tensioner 7 is activated only when an accident can no longer be avoided or has begun, and causes a larger increase in seat belt tension of 400 to 2000 N compared to the increase in tension when the reversible belt tensioner 3 is activated. The belt reel 5 is therefore driven with a significantly larger torque and higher rotational acceleration when the irreversible belt tensioner 7 is activated than when the reversible belt tensioner 3 is activated.

[0034] The reversible belt tensioner 3 comprises an electric motor and a gearbox with a gear mechanism mounted therein that transfers the rotary drive motion of the electric motor to the drive wheel 20 .

[0035] The toothed ring 23 visible in Figure 2 is held in a rotatably fixed manner on the extension 8 of the belt reel 5. This toothed ring 23 has radially outer teeth which, at the fastening point of the toothed ring 23 on the extension 8, form teeth 231 fixed on the belt reel.

[0036] The housing part 25, visible in FIG. 2, is provided on the gearbox of the reversible belt tensioner 3, in which the drive wheel 20 is rotatably mounted. For this purpose, the housing part 25 has an annular axial extension 251 that passes through the central bearing opening of the drive wheel 20. Furthermore, a control element 22 is provided, which comprises an annular spring 221 and a plate element 222 fixed via the annular spring 221, by which the control element is fixed in a frictionally engaged manner to the axial extension 251. In addition, a coupling pawl 21 is provided, which is arcuately shaped and has bearing pins 211 projecting from both sides of one of its ends. Furthermore, an annular cover disk 24 is provided, which has a bearing opening 241, in which the coupling pawl 21 is attached on one side by the bearing pin 211, which, in turn, engages with a bearing opening of the drive wheel 20 (not shown) with its other side. Thus, the coupling claws 21 are attached to both sides of the drive wheel 20 and the cover disc 24 .

[0037] 3 and 4, the toothed ring 23 and the coupling pawl 21 are arranged so that the coupling pawl 21 faces and encompasses the toothing 231 fixed on the belt reel with its radially shorter inner side 219. The coupling pawl 21 has, on its shorter inner side 219, a toothing formed by a first tooth 214, a second tooth 215 and a third tooth 216. The teeth 214, 215 and 216 of the coupling pawl 21 therefore face the toothing 231 fixed on the belt reel. Furthermore, at its end facing the first tooth 214, further away from the bearing pin 211, the coupling pawl 21 has an end face contact surface 217 facing the force transmission surface 201 of the drive wheel 20.

[0038] 3 and 4, a first control contour 223 and a second control contour 224 are provided on the plate portion 222 of the control element 22. The first control contour 223 is realized by a radially inner edge flank of a curved spring arm 228, one end of which is fixed to the plate portion 222. The second control contour 224 is formed by a curved upper edge flank of a protrusion that protrudes axially from the plate portion 222. In addition, as can be seen in FIG. 5, an axially protruding block contour 225 is provided on the plate portion 222, having a first radially aligned block face 226 and a second circumferentially aligned block face 227. The coupling claw 21 is provided with a first axially projecting control pin 212 and a second axially projecting control pin 213, which project axially from the side of the coupling claw 21, which in the mounted position faces the plate part 222 of the control element 22. Conversely, the plate part 222 of the control element 22 is aligned so that the side with the two control contours 223 and 224 faces the side of the coupling claw 21 on which the control pins 212 and 213 are arranged.

[0039] In Figures 6 to 8, the coupling pawl 21 is enlarged and can be seen in different positions during the engagement movement of the toothed ring 23 with the toothed portion 231 fixed on the belt reel. As can be seen in Figure 6, the first tooth 214 is enlarged, shaped, and aligned so that it first engages in the toothed portion 231 fixed on the belt reel during the engagement movement. The first tooth 214 is the tooth adjacent to the end face contact surface 217 of the coupling pawl 21 and is therefore the foremost tooth of the coupling pawl 21. The first tooth 214 is therefore located at the end of the coupling pawl 21 further away from the bearing pin 211 and performs the largest pivot path compared to the other teeth 215 and 216 during the pivoting movement of the coupling pawl 21. During the engagement movement, the coupling pawl 21 first engages with the first tooth 214 in the toothed portion 231 fixed on the belt reel, thereby pre-aligning the coupling pawl 21 with respect to the toothed portion 231 fixed on the belt reel. The first tooth 214 therefore acts as a receiving tooth. Due to the pre-alignment of the coupling pawl 21, it then engages with the further teeth 215 and 216 in the toothing 231 fixed on the belt reel, without the engagement movement being blocked by the further teeth 215 and 216 in contact with the teeth on the toothing 231 fixed on the belt reel.

[0040] 7, if during the engagement movement at the toothing 231 fixed on the belt reel the coupling pawl 21 hits against the radially outer end face of the tooth of the toothing 231 fixed on the belt reel with its first tooth 214 in tooth-to-tooth contact, the engagement movement is briefly interrupted. Due to the enlarged design of the first tooth 214 as a receiving tooth, the other teeth 215 and 216 are not yet intentionally in contact with the toothing 231 fixed on the belt reel, so that instances of tooth-to-tooth contact are intentionally limited to the contact of the first tooth 214 only.

[0041] 8, the first tooth 214 is shaped on its radially inner end surface such that the end surface of the first tooth 214 encompasses an angle W of less than 30 degrees in the circumferential direction relative to the end surface of the adjacent tooth of the toothing 231 fixed on the belt reel. Thus, the first tooth 214 slides along the end surface of the tooth of the toothing 231 fixed on the belt reel without blocking the movement. After the first tooth 214 slides down, it then engages with the next gap leading to the next tooth of the toothing 231 fixed on the belt reel, and the engaging movement of the coupling pawl 21 is completed.

[0042] In Fig. 4 it can be seen that the coupling pawl 21 is in a pivoted, disengaged position. Starting from this position, the engagement movement of the coupling pawl 21 is initiated by driving the drive wheel 20 in the direction of the arrow S in Fig. 3. Due to the driving movement of the drive wheel 20, the coupling pawl 21 also rotates in the direction of the arrow S. In this case, the coupling pawl 21 with the first control pin 212 rests on the radially inwardly directed control section 2232 of the first control contour 223, along which the first control pin 212 of the coupling pawl 21 then slides during a further rotational movement. By the first control pin 212 sliding along the control section 2232 of the first control contour 223, the coupling pawl 21 is forced into an engagement movement directed radially inward in the direction of the toothing 231 fixed on the belt reel, the path of which is predetermined by the shape and alignment of the control section 2232. The pivoting movement of the coupling pawl 21 ends when it comes into contact with the force transmission surface 201 of the drive wheel 20 by its end contact surface 217. This position of the coupling pawl 21 can be seen in FIG. 3. To complete the engagement movement of the coupling pawl 21, the coupling pawl is then displaced further by the drive wheel 20 in the direction of arrow S beyond the force transmission surface 201 for the toothed ring 23 and the plate part 222 by the second control pin 213 until it comes into contact with the first blocking surface 226 of the blocking contour 225. The first blocking contour 225, together with the first blocking surface 226, therefore forms a stop for the movement of the coupling pawl 21. At the same time, the coupling pawl 21 is moved by the first control pin 212 into a position in which the first control pin 212 is arranged radially inward relative to the blocking part 2231 of the first control contour 223. The coupling pawl 21 is thus subsequently secured against unintentional pivoting off from the toothing 231 fixed on the belt reel. Moreover, in this engaged position, which can be seen in Figure 5, the coupling pawl 21 rests with the teeth 214, 215 and 216 in a force-transmitting manner on the teeth of the toothing 231 fixed on the belt reel.

[0043] The force transmission surface 201 of the drive wheel 20 is inclined radially outwardly and encompasses an angle E1 of approximately 15 to 30 degrees with respect to the radial direction opposite to the drive direction of the drive wheel 20 in the direction of the arrow S. The end face contact surface 217 of the coupling pawl 21 is aligned at the same angle E1 with respect to the radial direction in the engaged position of the coupling pawl and is aligned so as to rest flat against the force transmission surface 201 of the drive wheel 20. The tooth flanks of the teeth of the toothing 231 fixed on the belt reel and the opposing tooth flanks of the teeth 214, 215, and 216 of the coupling pawl 21 in the engaged position are aligned in the same direction as the force transmission surface angle E1 and also encompass angles E2-E4 of approximately 15-30 degrees opposite the drive direction of the drive wheel 20 in the direction of arrow S, so that the force vectors F1-F4 on the force transmission surface 201 are directed towards the radially outer end face contact surface 217 and from the teeth of the toothing 231 fixed on the belt reel to the teeth 214, 215, and 216. The angles E1-E4 do not have to be the same. They only need to be in the same radial direction and inclined with respect to the drive direction so that the force vectors F1-F4 are directed in the same circumferential direction in the direction of the drive rotational movement in the direction of arrow S. This counteracts any tendency of the tooth flanks and the end face contact surface 217 to slip off the force transmission surface 201 of the drive wheel 20. The force transmission surface 201 is part of the dimensionally stable contour of the drive wheel 20 and therefore forms a dimensionally stable abutment for the coupling claw 21 in the adjacent position in Figure 3. The coupling claw 21 rests flat on the force transmission surface 201 with its end face contact surface 217.

[0044] The drive force is thus transmitted from the drive wheel 20 via the coupling pawl 21 directly to the teeth 231 of the toothed ring 23 fixed on the belt reel and further to the belt reel 5. As a result, the bearing force FL absorbed in the bearing of the coupling pawl 21 via the bearing pin 211 can be reduced. Ideally, the coupling pawl 21 aligns the drive wheel 20 to such an extent that it is pulled onto the teeth 231, thereby reducing the bearing force in the bearing of the drive wheel 20 to zero. It is advantageous if the bearing of the coupling pawl 21 on the bearing pin 211 is arranged at the end remote from the end contact surface 217, so that the coupling pawl 21 introduces the torque applied by the force transmission surface 201 into the teeth 231 fixed on the belt reel without the bearing of the coupling pawl 21 being subjected to stress, since the coupling pawl is not located in the force transmission path from the force transmission surface 201 via the contact surface 217 to the teeth 231 fixed on the belt reel.

[0045] If the pre-accident situation ends and no accident occurs, the reversible belt tensioning is also stopped and the seat belt tension is reduced. For this purpose, the drive wheel 20 is briefly driven in the direction of arrow A in FIG. 4 opposite to the drive direction, whereby the coupling pawl 21 with the first control pin 212 is rotated circumferentially to such an extent that the first control pin 212 is no longer located radially inward relative to the blocking portion 2231 of the first control contour 223. At the same time, the coupling pawl 21 with the second control pin 213 comes into contact with the second control contour 224. The second control contour 224 is curved and directed radially outward so that the coupling pawl 21 slides off it during further rotation of the drive wheel 20 in the direction of arrow A and is pulled radially outward until it is again located in the disengaged position visible in FIG. 4.

[0046] If the pre-accident situation changes to an accident, the irreversible belt tensioner 7 is activated and the belt shaft 5 together with the toothed ring 23 and the teeth 231 fixed on the belt reel are suddenly driven in the retracting direction, which is shown by the direction of the arrow S in the left view of FIG. 9. At the start of the drive movement of the drive wheel 20, the coupling pawl 21 is still in the engagement position corresponding to the position of the coupling pawl 21 in FIG. 5. Due to the rotational movement of the toothed ring 23, the coupling pawl 21 is forced radially outward by the teeth of the toothed ring 231 fixed on the belt reel, which slide on the teeth 214, 215 and 216, and the first control pin 212 displaces the spring arm 228 radially outward, and the second control pin 213 moves radially outward on the first block face 226 of the block contour 225, as can be seen in the central view of FIG. 9. Due to the deformation of the spring arms 228, an outer circumferential force is exerted on the plate element 222 of the control element 22, which displaces the plate element 222 in the direction of arrow R as soon as the second control pin 213 no longer rests laterally on the first block face 226. By displacing the plate element 222, the plate element moves into a position where it supports the second control pin 213 radially inwardly by the second block face 227 of the block contour 225. Furthermore, when the first control pin 212 overcomes the spring arms 228, the spring arms rebound and block the first control pin 212 from moving backward, as can be seen in the right-hand view of FIG. 9 . The coupling connection between the reversible belt tensioner 3 and the belt reel 5 is then released, and the irreversible belt tensioner 7 can drive the belt reel 5 without interference from the reversible belt tensioner 3. The spring arms 228 are aligned so that their free elastic ends extend from their fixed ends in the circumferential direction in the direction of rotation of the drive wheel 20 during the drive movement. On the one hand, this allows for a radial spring movement, thereby compensating for manufacturing errors. In addition, the orientation of the spring arms 228 in the direction of the drive movement of the drive wheel 20 forces the movement of the plate element 222 in the direction of the arrow R, i.e., in the direction opposite to the direction of rotation of the drive wheel 20, during the drive movement.

[0047] The coupling pawl 21 is then irreversibly blocked against pivotal movement in the opposite direction to the engaged position, but this does not adversely affect the function of the belt retractor, since the belt retractor must be replaced anyway after activation of the irreversible belt tensioner 7.

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 having a drive wheel (20), wherein the drive wheel drives the belt reel (5) in the winding direction via the drive wheel (20) when in operation, - A reliably controlled tensioner coupling that transfers drive motion from the drive wheel (1) to the belt reel (5), wherein the tensioner coupling is - At least one coupling claw (21) mounted on the drive wheel (20) is capable of moving to engage and disengage with teeth (231) fixed on the belt reel (5) in order to establish and disengage the rotational connection of the drive wheel (20), - A control element (22) having a first control contour (223) for controlling the engagement movement of the coupling claw (21) in the teeth (231) fixed on the belt reel, - A first control pin (212) is provided on the coupling claw (21), and the coupling claw slides on the first control contour (223) during engagement movement by the first control pin. - The first control contour (223) is formed by a spring arm (228) fixed to the control element (22) at one end. - The first control pin (212) slides along the spring arm (228) from the fixed end to the free end during the engagement movement of the coupling claw (21), - The connecting claw (21) is forced radially outward in the winding direction when rotational movement occurs of the teeth (231) fixed on the belt reel. - The control element (22) is forced to perform relative motion via the compressive force applied to the spring arm (228) by the first control pin (212), during which the second control pin (213) of the coupling claw (21) slides on the second block surface (227), - The second blocking surface (227) blocks the coupling claw (21) from pivoting motion directed radially inward toward the teeth (231) fixed on the belt reel. Belt retractor (1).

2. - The radially extending force transmission surface (201) is provided on the drive wheel (20), and the coupling claw (21) is arranged to contact the contact surface (217) by the engagement movement of the teeth (231) fixed on the belt reel. - The belt retractor (1) according to claim 1, wherein the drive wheel (20) applies a compressive force in the outer circumferential direction of the drive wheel (20) and drives the coupling claw (21) to the teeth (231) fixed on the belt reel at the engagement position so as to transmit the rotational motion to the belt reel (5) via the force transmission surface (201).

3. - The belt retractor (1) according to claim 2, wherein the force transmission surface (201) is inclined radially with respect to the rotation axis of the drive wheel (20), and the inclination is aligned with the teeth of the tooth portion (231) fixed on the belt reel.

4. - The belt retractor (1) according to claim 2, wherein the force transmission surface (201) is arranged such that the coupling claw (21), which is stationary on the force transmission surface at the engagement position, is positioned without contacting the first control contour (223).

5. - The belt retractor (1) according to claim 2, wherein at least one first tooth (214) is provided on the coupling claw (21), and the coupling claw (21) engages with the at least one first tooth at the tooth portion (231) fixed on the belt reel at the engagement position.

6. - The belt retractor (1) according to claim 5, wherein the end face of the first tooth (214) facing the tooth portion (231) fixed on the belt reel is aligned such that the angle (W) between the end face of the first tooth (214) and the end face of the tooth portion (231) fixed on the belt reel that is directed radially outward is less than 30 degrees.

7. - At least one second tooth (215, 216) is provided, - The first or second teeth (214, 215, 216) are designed as enlarged receiving teeth, such that the connecting claw (21) first engages with the tooth portion (231) fixed on the belt reel during the engagement motion. The belt retractor (1) according to claim 5.

8. - The belt retractor (1) according to claim 7, wherein the receiving teeth are formed by the first teeth (214) adjacent to the contact surface (217).

9. - The first control contour (223) has a lock section (2231) aligned in the outer peripheral direction, - The first control pin (212) is positioned on the coupling claw (21) such that the control pin is positioned radially inward relative to the lock section (2231) at the engagement position of the coupling claw (21), The belt retractor (1) according to claim 2.

10. - A second control contour (224) for controlling the disengagement movement of the coupling claw (21) is provided on the control element (22) as described in claim 1, the belt retractor (1).

11. - The belt retractor (1) according to claim 10, wherein a second control pin (213) is provided on the coupling claw (21), and the coupling claw slides on the second control contour (224) by the second control pin during the disengagement movement.

12. - The belt retractor (1) according to claim 2, wherein, at the engagement position, a block contour (225) forming a stop portion for the coupling claw (21) is provided on the control element (22).

13. - The block contour (225) has a first block surface (226) aligned in the radial direction and a second block surface (227) aligned in the outer peripheral direction, - The first block surface (226) is characterized in that it forms the stopping portion. The belt retractor (1) according to claim 12.

14. - The belt retractor (1) according to claim 1, characterized in that the coupling claw (21) has a curved, bow-shaped form, and the shorter curved side surface (219) is positioned to face the teeth (231) fixed on the belt reel.

15. - The belt retractor (1) according to claim 2, characterized in that the coupling claw (21) is pivotably mounted on a pivot bearing (211) located on the end of the coupling claw (21) which is further away from the contact surface (217).

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