Seat belt retractor for a seat belt device of a motor vehicle

Abstract

The invention relates to a belt retractor (1) for a seat belt device of a motor vehicle, comprising: a rotatably mounted belt reel (5) on which a seat belt of the seat belt device can be wound; and a reversible belt tensioner having a drive wheel (20) which, when activated, drives the belt reel (5) in the winding direction via the drive wheel (20); and an actively controlled tensioner coupling which transmits a drive movement from the drive wheel (20) to the belt reel (5), the actively controlled tensioner coupling having at least one coupling pawl (21) and a control element (22), the at least one coupling pawl is mounted on the drive wheel (20) and can be moved into and out of engagement with a toothing (231) fixed on the seatbelt reel in order to establish and disconnect a rotational connection of the drive wheel (20), and a control element (223) having a first control profile (223), the coupling pawl (21) has a first control profile (223) for controlling an engagement movement of the coupling pawl (21) with a tooth fixed on the belt reel (231), a first control pin (212) is arranged on the coupling pawl (21), by means of which the coupling pawl slides on the first control profile (223) during the engagement movement, and the first control profile (223) has a blocking section (2231) aligned in the circumferential direction, the first control pin (212) is arranged on the coupling pawl (21) in such a way that, in the engaged position of the coupling pawl (21), the control pin is arranged radially inward with respect to the blocking section (2231).

Description

[0001] The invention relates to a belt retractor for a seat belt arrangement of a motor vehicle, the belt retractor having the features according to the preamble of claim 1 .

[0002] A belt retractor is used in a seat belt arrangement of a motor vehicle and serves to wind up one end of a seat belt which is provided for restraining an occupant. The belt retractor is fastened to the vehicle structure or to a vehicle seat fastened to the vehicle structure or to a bench seat fastened thereto. In its basic structure, the belt retractor has a frame which is provided for fastening purposes and a belt reel which is rotatably mounted in the frame, wherein the seat belt can be wound onto the belt reel. The belt reel is loaded in the winding direction via a spring and, in the event of a predetermined belt withdrawal acceleration being exceeded or a vehicle deceleration, further withdrawal of the seat belt can be prevented by means of a blocking device, so that the occupant is restrained before impacting the vehicle interior structure in order to prevent serious injuries.

[0003] In order to reduce the occupant load during restraint, force limiting devices have proven to be advantageous, which, when the belt reel is locked and a predetermined belt withdrawal force is exceeded, allow a force-limited rotation of the belt reel in the withdrawal direction and thus achieve a force-limited forward displacement of the occupant. Since the reduction in occupant load achieved thereby is directly related to the available forward displacement path, it has been found to be advantageous to tighten the slack belt present in the seat belt by means of a belt tensioner before activating 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] Among the belt tensioners, a distinction is made between reversible belt tensioners and irreversible belt tensioners or even performance tensioners. Reversible belt tensioners have a lower tensioning capacity of approximately 100 N to 800 N and are used to tighten the slack belt in dangerous situations in order to prepare for a possible subsequent accident. If no accident occurs subsequently, the seat belt will slacken again. Electric motors that can be controlled particularly well and reversibly have proven successful for driving reversible belt tensioners. Irreversible belt tensioners have a higher tensioning capacity of 400 N to 2000 N and are only activated when an accident can no longer be avoided, i.e. in the early stages of an accident. Irreversible belt tensioners are therefore always activated after reversible belt tensioners. Pyrotechnic drives that cannot be activated again after a one-time activation have proven to be the drive for irreversible belt tensioners, so that in this case the entire seat belt arrangement with the irreversible belt tensioner must be replaced.

[0005] In this case, the belt tensioner can be engaged at different locations of the seat belt, for example at the belt buckle, at the end fitting or even at the belt retractor. When the belt tensioner is used on the belt retractor, it abruptly drives the belt reel in the winding direction in the event of activation and thereby tightens the slack belt present in the seat belt. In the sense of the present invention, the term "belt tensioner" is understood only as a belt tensioner which is arranged on the belt retractor and drives the belt reel. Since the belt reel must be able to rotate substantially freely in normal use for fastening and unfastening the belt, the drive of the reversible belt tensioner and the irreversible belt tensioner is connected to the belt reel via a coupling only in the event of activation. The couplings should be designed so that they do not inadvertently establish a rotational connection, otherwise the normal use of the belt retractor would be hampered by the rotational movement of the belt reel being disturbed.

[0006] Since the reversible belt tensioner should be deactivated again and the belt retractor should be used normally again in the event of a subsequent accident, the coupling of the reversible belt tensioner must also be designed to be reversible. Furthermore, when an accident occurs and the irreversible belt tensioner is activated, the coupling of the reversible belt tensioner must also be intentionally disengaged so that the drive movement of the irreversible belt tensioner is not disturbed by the still engaged coupling of the reversible belt tensioner.

[0007] Furthermore, the coupling of the various belt tensioners must be designed in such a way that it automatically establishes a rotational connection between the drive and the belt reel when the drive is activated, which can be achieved, for example, by friction, by inertial forces or by a control profile. Thus, the movement of the coupling is actively controlled by the initial movement of the drive.

[0008] Therefore, the coupling needs to automatically perform a coupling movement when the drive device is activated, but intentionally not perform a coupling movement in other cases in order to prevent an undesired coupling connection.

[0009] For example, DE 10059227 C1 of the applicant discloses a belt retractor with a reversible belt tensioner having a friction-controlled coupling with two coupling pawls and a brake element. The coupling pawls are slidably mounted on a drive wheel and, in order to establish the coupling connection, engage in an internal toothing of a clutch bell connected to the belt shaft in a rotationally fixed manner.

[0010] From DE 10 2014 009 038 B4 a coupling for a belt tensioner is also known, which coupling has two coupling pawls mounted on a drive wheel, referred to herein as an input element, which, in order to establish the coupling connection, engage in an external toothing of an output element connected to the belt reel. In order to control the movement of the coupling element, a control element coupled to the inertial mass is provided, on which input control geometry and output control geometry for controlling the movement of the coupling pawls are provided.

[0011] Against this background, it is an object of the present invention to provide a seat belt retractor of the generic type in which the coupling pawl is securely held in the engaged position after the engaging movement.

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

[0013] According to the basic concept of the invention, it is proposed that a first control pin is provided on the coupling pawl, with which the coupling pin slides on a first control contour during the engagement movement. The coupling pawl rests together with the first control pin on a first control contour, which defines by its shape the course of the engagement movement of the coupling pawl in a toothing fixed to the belt reel, in such a way that the first control pin slides on the toothing. 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 so that it is arranged radially inwardly relative to the blocking portion in the engagement position of the coupling pawl. Due to the blocking portion of the first control contour, during the engagement of the toothing during reversible pretensioning, the coupling pawl is blocked against a radially outwardly directed control movement from the toothing fixed to the belt reel.

[0014] It is further proposed that the first control contour is formed by a spring arm which is fixed at one end to the control element and that 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. By designing the first control contour as a spring arm and the proposed arrangement thereof, the control pin and the coupling pawl can perform a slight radial movement relative to the first control contour during the engagement movement. This prevents inhibition of the movement due to shape inaccuracies or different friction forces. The spring arm is aligned so that the free elastic end extends from the fixed end during the drive movement in the circumferential direction and in the direction of rotation of the drive wheel.

[0015] It is further proposed that a second control contour is provided on the control element for controlling the disengagement movement of the coupling pawl. The second control contour controls the disengagement movement of the coupling pawl in its course by the shape of the second control contour alone, regardless of the engagement movement of the coupling pawl.

[0016] In this case, a second control pin can preferably be provided on the coupling pawl, with which control pin the coupling pin slides on the second control contour during the disengaging movement.

[0017] It is further proposed that a blocking profile is provided on the control element, which forms a stop for the coupling pawl in the engaged position. After the engagement movement is over, the blocking profile defines the final position of the coupling pawl. In addition, this limits any further differential movement of the control profile relative to the coupling pawl.

[0018] It is further proposed that the blocking contour has a first blocking surface aligned in the radial direction and a second blocking surface aligned in the circumferential direction, wherein the first blocking surface forms a stop and pushes the coupling pawl radially outwards during a rotational movement of the toothing in the reeling direction of the seat belt, and by the compression force thereby exerted by the first control pin on the spring arm forces the control element to perform a relative movement, during which the second control pin slides from the first blocking surface onto the second blocking surface, wherein the second blocking surface prevents the coupling pawl from performing a radially inward pivoting movement into the toothing fixed to the belt reel. The proposed solution means that, when the irreversible belt tensioner is activated and the belt reel is thereby rotated in the reeling direction, the coupling pawl is automatically pushed out of the engagement position and the coupling connection is released. In addition, the coupling pawl is simultaneously blocked by a support on the second blocking surface to prevent a repeated engagement movement in the toothing fixed to the belt reel.

[0019] It is further proposed that a force transmission surface extending in a radial direction is provided on the driving wheel, and the force transmission surface is arranged so that the coupling pawl abuts against the force transmission surface with an end face contact surface due to the engaging movement engaging in the tooth portion, and the driving wheel drives the coupling pawl into the tooth portion fixed on the seat belt reel in the engaged position, so as to transmit the rotational movement to the seat belt reel via the force transmission surface while applying a compressive force in the circumferential direction of the driving wheel.

[0020] Due to the force transmission surface provided on the drive wheel and extending in the radial direction and the drive of the coupling pawl realized on the force transmission surface, which drive is transmitted to the belt reel by the engagement of the coupling pawl in the toothing which is in rotationally fixed connection with the belt reel, the drive force is transmitted more immediately and therefore more directly from the drive wheel to the coupling pawl and the belt reel. In this case, the bearing forces to be absorbed by the coupling pawl on the drive wheel in the rotary joint are reduced at the same time by distributing the bearing forces between the rotary joint and the force transmission surface extending in the radial direction. Ideally, the drive torque can even be transmitted without bearing loads on the coupling pawl by arranging the rotary joint in such a way that it is outside the force transmission path from the force transmission surface via the coupling pawl to the toothing which is fixedly arranged on the belt reel.

[0021] It is further proposed that the force transmission surface has an inclination in the radial direction relative to the rotation axis of the drive wheel, which inclination is aligned with the teeth of the toothing fixed to the belt reel. Due to the proposed alignment of the force transmission surface relative to the alignment of the teeth of the toothing fixed to the belt reel, the teeth form unidirectional reaction surfaces for the transmission of forces, so that the force vectors are also unidirectional during the transmission of forces from the drive wheel to the coupling pawl and from the coupling pawl to the toothing fixed to the belt reel. This allows the force transmission conditions to be optimized, in particular with regard to avoiding slippage of the force transmission surface as much as possible.

[0022] It is further proposed that the force transmission surface is arranged such that the coupling pawl resting thereon is arranged not to be in contact with the first control contour. This means that the first control contour is not loaded during the drive of the belt reel during reversible belt tensioning. This also ensures that force transmission occurs only via the force transmission surface of the drive wheel, the end contact surface of the coupling pawl and the bearing of the coupling pawl in the rotary joint.

[0023] It is further proposed that the coupling pawl is pivotably mounted in a pivot bearing which is arranged at the end of the coupling pawl remote from the end face contact surface. During the pivoting movement, the coupling pawl pivots radially inwards together with the end face contact surface and in doing so contacts the force transmission surface of the drive wheel via the contact surface. Due to the provided arrangement of the pivot bearing, the coupling pawl executes the greatest possible pivoting path with its contact surface.

[0024] It is further proposed that at least one first tooth is arranged on the coupling pawl, which in the engaged position engages with the first tooth in a toothing fixed to the belt reel. The coupling pawl thus has a profile that matches the toothing fixed to the belt reel, wherein the toothing geometry of the first tooth on at least one tooth flank corresponds to the tooth flank of the toothing fixed to the belt reel.

[0025] It is further proposed that the face of the tooth is aligned with the end face of the toothed section fixed on the belt reel such that the angle between the end face of the tooth and the radially outwardly pointing end face of the tooth of the toothed section is less than 30 degrees. Due to the proposed alignment of the end face of the tooth with the end face of the tooth of the toothed section fixed on the belt reel, in the case of tooth against tooth, the tooth slides off the tooth of the toothed section fixed on the belt reel with very little compression force without getting stuck.

[0026] It is further proposed that at least one second tooth is provided and that the first tooth or the second tooth is designed to form an enlarged latching tooth with which the coupling pawl first engages with the toothing fixed to the belt reel during the engagement movement. The enlarged latching tooth first engages with the toothing fixed to the belt reel and thereby causes a prealignment of the coupling pawl with the toothing fixed to the belt reel, so that the further tooth then engages in the toothing fixed to the belt reel in a defined alignment without itself being blocked in the tooth-to-tooth situation.

[0027] In this case, the latching tooth is preferably formed by a first tooth adjacent to the end-face contact surface. Thus, the coupling pawl is pulled into the toothing fixed to the belt reel starting from the end facing the end-face contact surface. This is particularly advantageous when the coupling pawl is mounted in a pivot bearing at the distal end, since the latching tooth or the first tooth can thereby better first engage with the toothing fixed to the belt reel and in doing so perform the maximum pivoting path. Due to the fact that the latching tooth in the form of the first tooth performs the maximum pivoting path, it is particularly easy to ensure that the latching tooth first engages with the toothing fixed to the belt reel and thus pre-aligns the coupling pawl.

[0028] It is further proposed that the coupling pawl has a curved arc shape and is arranged such that the shorter side of the arc faces the toothed portion fixed to the belt reel. The curved coupling pawl thus engages around the toothed portion fixed to the belt reel and is formed with the shorter side of the curve or also the inner side of the force transmission surface. For this purpose, the inner force transmission surface can, for example, be provided with one or more teeth.

[0029] The present invention will be explained below using preferred embodiments with reference to the accompanying drawings. In the accompanying drawings:

[0030] Figure 1 is a seat belt retractor with a reversible seat belt tensioner according to the present invention; and

[0031] Figure 2 is a drive wheel having a tensioner coupling and a housing portion for transmitting the rotational movement of a reversible seat belt tensioner; and

[0032] Figure 3 is the driving wheel, the coupling pawl and the toothing fixed to the belt reel during the engagement movement; and

[0033] Figure 4 is the drive wheel, the coupling pawl and the teeth fixed to the seat belt reel in the disengaged position; and

[0034] Figure 5 is the driving wheel in the engaged position, the coupling pawl and the teeth fixed to the seat belt reel; and

[0035] Figure 6 is a drive wheel, a coupling pawl and a toothed portion fixed to the belt reel in a first contact position during the engaging movement; and

[0036] Figure 7 is a drive wheel, a coupling pawl and a toothed portion fixed to the belt reel in a tooth-to-tooth position of a first tooth during the engaging movement; and

[0037] Figure 8 is an enlarged view of the drive wheel, the coupling pawl and the toothed portion fixed to the belt reel in a tooth-to-tooth position of a first tooth during an engaging movement; and

[0038] Fig. 9 The drive wheel, the coupling pawl and the toothing fastened to the belt reel are in different positions during activation of the irreversible belt tensioner.

[0039] Figure 1 A belt retractor 1 according to the invention is shown, which has a reversible belt tensioner 3, a drive wheel 20, a tensioner coupling 2 and a winding unit 4. The winding unit 4 comprises as basic components a belt reel 5 which is rotatably mounted in a frame 6 having an axial extension 8 and an irreversible pyrotechnic belt tensioner 7 or a power tensioner.

[0040] The reversible seat belt tensioner 3 is activated in the pre-accident situation and is used to tighten the seat belt in preparation for a possible accident. The seat belt is tightened with a tension of 100N to 800N, wherein the tension can be selected in different levels according to the specifications of the vehicle manufacturer, or can be designed in stages according to various pre-accident specific standards so that the tension increases gradually.

[0041] The irreversible belt tensioner 7 is activated only when an accident can no longer be avoided or at the very beginning of an accident and causes a greater increase in tension in the seat belt of 400 N to 2000 N than the increase in tension when the reversible belt tensioner 3 is activated. Therefore, when the irreversible belt tensioner 7 is activated, the belt reel 5 is driven with a greater torque and a higher rotational acceleration than when the reversible belt tensioner 3 is activated.

[0042] The reversible seat belt tensioner 3 includes an electric motor and a gear box having a gear mechanism installed therein, which transmits the rotational drive motion of the electric motor to the drive wheel 20 .

[0043] like Figure 2 The toothed ring 23 shown is held in a rotationally fixed manner on the extension 8 of the belt reel 5. The toothed ring 23 has a radially outer toothing which, in the fastened position of the toothed ring 23 on the extension 8, forms a toothing 231 fixed to the belt reel.

[0044] like Figure 2 The housing part 25 shown is arranged on a 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, which passes through a central bearing opening in the drive wheel 20. In addition, a control element 22 is provided, which has an annular spring 221 and a plate element 222 fixed via the annular spring 221, which plate element is fixed to the axial extension 251 in a frictionally engaged manner via the annular spring 221. In addition, an arc-shaped coupling pawl 21 is provided, which has a bearing pin 211 protruding on both sides at one of its ends. In addition, an annular covering disk 24 with a bearing opening 241 is provided, in which one side of the coupling pawl 21 is mounted with the bearing pin 211, while the other side of the bearing pin 211 engages in a bearing opening (not visible) of the drive wheel 20. Therefore, both sides of the coupling pawl 21 are mounted in the drive wheel 20 and on the covering disk 24.

[0045] The toothed ring 23 and the coupling pawl 21 are arranged so that the coupling pawl 21 faces the toothed portion 231 fixed on the safety belt reel with the radially inner shorter side 219 and surrounds the toothed portion. Figure 3 and Figure 4 As shown. The coupling pawl 21 has a toothed portion on its shorter inner side 219, which is 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 thus face the toothed portion 231 fixed to the belt reel. In addition, the coupling pawl 21 has an end face contact surface 217 at its end away from the bearing pin 211 and facing the first tooth 214, which is opposite to the force transmission surface 201 of the drive wheel 20.

[0046] The first control contour 223 and the second control contour 224 are arranged on the plate portion 222 of the control element 22, such as Figure 3 and Figure 4As shown. The first control contour 223 is realized by the radially inner edge side of the curved spring arm 228, one end of which is fixed to the plate portion 222. The second control contour 224 is formed by the curved upper edge side of the protrusion axially protruding from the plate portion 222. In addition, as shown Figure 5 As shown, an axially protruding blocking profile 225 is provided on the plate portion 222, which has a radially aligned first blocking surface 226 and a second blocking surface 227 aligned in the circumferential direction. The coupling pawl 21 is provided with a first axially protruding control pin 212 and a second axially protruding control pin 213, which axially protrude from the side of the plate portion 222 of the coupling pawl 21 that faces the control element 22 in the installed position. Conversely, the plate portion 222 of the control element 22 is aligned so that the side with the two control profiles 223 and 224 faces the side of the coupling pawl 21 on which the control pins 212 and 213 are arranged.

[0047] exist Figures 6 to 8 In the figure, the coupling pawl 21 is enlarged and can be seen in different positions during the engagement movement in the toothing 231 of the toothed ring 23 fixed on the belt reel. Figure 6 As shown, 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 that abuts the end face contact surface 217 of the coupling pawl 21 and is therefore the frontmost tooth of the coupling pawl 21. Therefore, the first tooth 214 is arranged at the end of the coupling pawl 21 that is 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, whereby the coupling pawl 21 is pre-aligned relative to the toothed portion 231 fixed on the belt reel. The first tooth 214 thus acts as a latching tooth. Due to the prealignment of the coupling pawl 21 , it then engages with the toothing 231 fixed to the belt reel via the further teeth 215 and 216 without the engaging movement being blocked by tooth-to-tooth contact of the teeth 215 and 216 with the toothing 231 fixed to the belt reel.

[0048] If during the engagement movement in the toothing 231 fixed to the belt reel, the coupling pawl 21 is Figure 7 In the tooth-on-tooth situation shown, the first tooth 214 strikes the radially outer end face of the tooth of the toothed section 231 fixed on the belt reel, and the engagement movement is briefly interrupted. Since the first tooth 214 is designed as an enlarged latch tooth, the other teeth 215 and 216 intentionally have not yet contacted the toothed section 231 fixed on the belt reel, so that the tooth-on-tooth example is intentionally limited to the contact of the first tooth 214.

[0049] As in Figure 8 As can be seen in the enlarged view of , the first tooth 214 is formed on its radially inner end face so that the end face of the first tooth 214 and the end face of the adjacent tooth of the toothed portion 231 fixed on the seat belt reel enclose an angle W of less than 30 degrees in the circumferential direction. Therefore, the first tooth 214 slides along the end face of the tooth of the toothed portion 231 fixed on the seat belt reel without blocking the movement. After the first tooth 214 has slid out, it engages with the next tooth of the toothed portion 231 fixed on the seat belt reel in the subsequent gap, and the engagement movement of the coupling pawl 21 ends.

[0050] exist Figure 4 In the figure, the coupling pawl 21 can be seen in the pivoted out of engagement position. Starting from this position, by following the Figure 3 The drive wheel 20 is driven in the direction of the arrow S in order to trigger the engagement movement of the coupling pawl 21. Due to the drive 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 abuts against the radially inclined 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 further rotational movement. By sliding of the first control pin 212 along the control section 2232 of the first control contour 223, the coupling pawl 21 is forced to perform a radially inwardly directed engagement movement in the direction of the toothed portion 231 fixed to the belt reel, wherein the route of the engagement movement is predetermined by the shape and alignment of the control section 2232. The pivoting movement of the coupling pawl 21 is terminated when the coupling pawl 21 contacts the force transmission surface 201 of the drive wheel 20 via its end face contact surface 217. Figure 3 This position of the coupling pawl 21 can be seen in . In order to complete the engagement movement of the coupling pawl 21, the coupling pawl is then further displaced by the drive wheel 20 on the force transmission surface 201 relative to the toothed ring 23 and the plate portion 222 in the direction of the arrow S until it comes into contact with the first blocking surface 226 of the blocking profile 225 via the second control pin 213. Therefore, the first blocking profile 225 together with the first blocking surface 226 forms a stop for the movement of the coupling pawl 21. At the same time, the coupling pawl 21 moves together with the first control pin 212 to a position in which the first control pin 212 is arranged radially inwardly relative to the blocking portion 2231 of the first control profile 223. Therefore, the coupling pawl 21 is then secured to prevent accidental pivoting out from the toothed portion 231 fixed to the belt reel. In addition, in Figure 5 In this engaged position, which can be seen in FIG. 2 , the coupling pawl 21 rests with its teeth 214 , 215 and 216 on the teeth of a toothing 231 which is fixed to the belt reel in a force-transmitting manner.

[0051] The force transmission surface 201 of the drive wheel 20 is inclined radially outward and forms an angle E1 of about 15 to 30 degrees with the radial direction opposite to the driving direction of the drive wheel 20 in the direction of arrow S. The end surface contact surface 217 of the coupling pawl 21 is aligned in such a way that, in the engaged position of the coupling pawl, the coupling pawl is aligned in the radial direction at the same angle E1 and flatly abuts against the force transmission surface 201 of the drive wheel 20. The tooth flanks of the teeth of the toothed section 231 fixed to 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 angle E1 of the force transmission surface and also enclose an angle E2 to E4 of about 15 to 30 degrees in the direction of the arrow S opposite to the driving direction of the drive wheel 20, so that the force vectors F1 to F4 on the force transmission surface 201 point radially outward to the end contact surface 217 and from the teeth of the toothed section 231 fixed to the belt reel to the teeth 214, 215 and 216. The angles E1 to E4 do not have to be the same. They only have to be in the same direction with respect to the radial direction and inclined with respect to the driving direction so that the force vectors F1 to F4 point in the same circumferential direction in the direction of the arrow S in the direction of the driving rotational movement. This can counteract the tendency of the tooth flanks and the end 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 shape-stable contour of the drive wheel 20 and is therefore in the direction of the arrow S. Figure 3 In the adjacent position of the coupling pawl 21, a dimensionally stable abutment is formed for the coupling pawl 21. The coupling pawl 21 rests flatly on the force transmission surface 201 with its end contact surface 217.

[0052] Therefore, the driving force is directly transmitted from the driving wheel 20 via the coupling pawl 21 to the toothed portion 231 fixed to the belt reel of the toothed ring 23 and further to the belt reel 5. Therefore, the bearing force FL absorbed by the bearing of the coupling pawl 21 via the bearing pin 211 can be reduced. Ideally, the coupling pawl 21 is pulled onto the toothed portion 231 and thereby aligns the driving wheel 20 to such an extent that the bearing force in the bearing of the driving wheel 20 is reduced to 0. Advantageously, the bearing of the coupling pawl 21 on the bearing pin 211 is arranged at an end away from the end surface contact surface 217, so that the coupling pawl 21 introduces the torque applied by the force transmission surface 201 into the toothed portion 231 fixed to the belt reel, while the bearing of the coupling pawl 21 is not tensioned because it is not located in the force transmission path from the force transmission surface 201 via the contact surface 217 to the toothed portion 231 fixed to the belt reel.

[0053] If the pre-accident situation has ended and has not turned into an accident, the reversible belt tensioning is also stopped and the tension in the seat belt is reduced. To this end, the drive wheel 20 is rotated in the opposite direction of the drive. Figure 4, whereby the coupling pawl 21 with the first control pin 212 is rotated in the circumferential direction to such an extent that the first control pin 212 is no longer arranged radially inwardly to the blocking portion 2231 of the first control contour 223. At the same time, the coupling pawl 21 contacts the second control contour 224 with the second control pin 213. The second control contour 224 is curved and points radially outward, so that the coupling pawl 21 slides away from the second control contour during the further rotational movement of the drive wheel 20 in the direction of the arrow A and is pulled radially outward until the second control contour is arranged again in the disengaged position, as shown in FIG. Figure 4 shown.

[0054] If the pre-accident situation turns into an accident, the irreversible belt tensioner 7 is activated and the belt shaft 5 together with the toothed ring 23 and the toothing 231 fastened to the belt reel is suddenly driven in the winding direction. Fig. 9 The left side view is shown by the direction of the arrow S. At the beginning of the driving movement of the drive wheel 20, the coupling pawl 21 is still in the engaged position, which corresponds to the engaged position. Figure 5 Due to the rotational movement of the toothed ring 23, the coupling pawl 21 is pushed radially outwards by the teeth of the toothed section 231 fixed to the belt reel sliding on the teeth 214, 215 and 216, wherein the first control pin 212 displaces the spring arm 228 radially outwards and the second control pin 213 moves radially outwards on the first blocking surface 226 of the blocking contour 225, as shown in FIG. Fig. 9 As a result of the deformation of the spring arms 228, a circumferential force is exerted on the plate element 222 of the control element 22, which displaces the plate element 222 in the direction of the arrow R as soon as the second control pin 213 no longer bears laterally against the first blocking surface 226. By displacing the plate element 222, it is moved together with the second blocking surface 227 of the blocking profile 225 into a position in which the second control pin 213 is radially supported on the inside. In addition, the first control pin 212 overcomes the spring arms 228, so that the spring arms rebound the first control pin 212 and prevent the first control pin from moving backwards, as shown in FIG. Fig. 9 . As shown in the right side view of . Subsequently, the coupling connection between the reversible seat belt tensioner 3 and the seat belt reel 5 is released, and the irreversible seat belt tensioner 7 can drive the seat belt reel 5 without interference from the reversible seat belt tensioner 3. The spring arm 228 is aligned so that the free elastic end extends from the fixed end in the circumferential direction and the rotation direction of the drive wheel 20 during the driving movement. On the one hand, this realizes a radial spring movement, so that manufacturing errors can be compensated. In addition, the spring arm 228 forces the plate element 222 to move in the direction of arrow R along the driving movement direction of the drive wheel 20 during the driving movement, that is, opposite to the rotation direction of the drive wheel 20.

[0055] The coupling pawl 21 is then irreversibly blocked from a rearward pivoting movement into the engaged position, but this has no detrimental effect on the function of the belt retractor, since the belt retractor must be replaced after activation of the irreversible belt tensioner 7 anyway.

Claims

1. A seat belt retractor (1) for a seat belt assembly of a motor vehicle, the seat belt retractor comprising: - a rotatably mounted belt reel (5), on which the seat belt of the seat belt arrangement can be wound; and - a reversible belt tensioner having a drive wheel (20) which, when activated, drives the belt reel (5) via the drive wheel (20) in a winding direction; and - an actively controlled tensioner coupling, which transmits the drive movement from the drive wheel (1) to the belt reel (5), the actively controlled tensioner coupling having: at least one coupling pawl (21) mounted on the drive wheel (20) and movable into and out of engagement with a toothed portion (231) fixed to the belt reel in order to establish and disconnect the 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) in the toothing fastened to the belt reel (231), It is characterized in that a first control pin (212) is arranged on the coupling pawl (21), the coupling pawl sliding on the first control contour (223) by means of the control pin during the engagement movement, and - the first control contour (223) has a locking section (2231) aligned in the circumferential direction, and The first control pin (212) is arranged on the coupling pawl (21) so that it is in the engaged position of the coupling pawl (21), the control pin being arranged radially inwards relative to the locking section (2231).

2. The seat belt retractor according to claim 1, characterized in that: - the first control profile (223) is formed by a spring arm (228) fixed at one end to the control element (22), and - the first control pin (212) slides on the spring arm (228) from a fixed end to a free end during the engagement movement of the coupling pawl (21).

3. The seat belt retractor according to claim 1, characterized in that A second control contour (224) for controlling the disengagement movement of the coupling pawl (21) is arranged on the control element (22).

4. The seat belt retractor (1) according to claim 3, characterized in that: A second control pin (213) is arranged on the coupling pawl (21), with which the coupling pawl slides on the second control contour (224) during the engagement movement.

5. The seat belt retractor (1) according to one of claims 1 to 4, characterized in that A blocking contour (225) is provided on the control element (22), said blocking contour forming a stop for the coupling pawl (21) in the engaged position.

6. The seat belt retractor (1) according to one of claims 1 or 2, one of claims 3 or 4 and according to claim 5, characterized in that The blocking profile (225) has a first blocking surface (226) aligned in the radial direction and a second blocking surface (227) aligned in the circumferential direction, wherein - the first blocking surface (226) forms the stop, and - in the event of a rotational movement of the toothed section (231) fixed to the belt reel, the coupling pawl (21) is pushed radially outwards in the take-up direction, and - via the compressive force thereby exerted by the first control pin (212) on the spring arm (228), the control element (22) is forced to perform a relative movement, during which the second control pin (213) slides from the first blocking surface (226) to the second blocking surface (227), wherein The second blocking surface (227) prevents the coupling pawl (21) from performing a radially inwardly directed pivoting movement into the toothing fixed to the belt reel (231).

7. The seat belt retractor according to claim 1, characterized in that a force transmission surface (201) extending in radial direction is provided on the drive wheel (20) and is arranged so that the coupling pawl (21) comes into contact with the front contact surface (217) by the engagement movement in the toothed portion (231) fixed to the belt reel, and - the drive wheel (20) drives the coupling pawl (21) in the engaged position into the toothed portion fixed to the belt reel (231) to transmit the rotational movement to the belt reel (5) via the force transmission surface (201) while applying a compressive force in the circumferential direction of the drive wheel (20).

8. The seat belt retractor (1) according to claim 7, characterized in that: The force transmission surface (201) has an inclined portion in the radial direction relative to the rotation axis of the drive wheel (20), the inclined portion being aligned with the teeth of the toothed portion (231) fixed to the belt reel.

9. The seat belt retractor (1) according to claim 7, characterized in that The force transmission surface (201) is arranged such that the coupling pawl (21) resting thereon in the engaged position is arranged not to be in contact with the first control contour (223).

10. The seat belt retractor (1) according to one of claims 7 to 9, characterized in that The coupling pawl (21) is pivotably mounted in a pivot bearing (211), which is arranged on the end of the coupling pawl (21) remote from the end contact surface (217).

11. The seat belt retractor (1) according to one of claims 1 to 10, characterized in that At least one first tooth (214) is provided on the coupling pawl (21), with which the coupling pawl (21) in the engaged position engages with the first tooth in the toothed section (231) fixed to the belt reel.

12. The seat belt retractor (1) according to claim 11, characterized in that: - The end face of the first tooth (214) facing the toothed portion (231) fixed on the seat belt reel is aligned so that the angle (W) between the end face of the first tooth (214) and the radially outwardly pointing end face of the tooth of the toothed portion (231) fixed on the seat belt reel is less than 30 degrees.

13. The seat belt retractor (1) according to claim 11 or 12, characterized in that - providing at least one second tooth (215, 216), and The first tooth or the second tooth (214, 215, 216) is designed as an enlarged latching tooth, with which the coupling pawl (21) first engages with the toothing (231) fixed to the belt reel during the engagement movement.

14. The seat belt retractor (1) according to claim 13, characterized in that: The latching tooth is formed by the first tooth (214) adjacent to the contact surface (217).

15. The seat belt retractor (1) according to one of claims 1 to 14, characterized in that The coupling pawl (21) has an arcuate curved shape and is arranged so that the shorter side (219) of the arc faces the toothed portion fixed to the belt reel (231).

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