Belt retractor for automobile seat belt system

Abstract

To provide a belt retractor in which the transmission of the driving motion of a drive wheel to a belt shaft is further improved. [Solution] The belt retractor (1) is a reversible belt tensioner equipped with a belt reel (5) and a drive wheel (20), and includes a drive wheel (20) that drives the belt reel (5) via the drive wheel (20), a tensioner coupling that transmits drive motion to the belt reel (5), a coupling pawl (21) that engages with a tooth portion (231), and a control element (22) having a first control contour (223) that controls the engagement movement of the coupling pawl (21) into the tooth portion (231), and a force transmission surface (201) is provided on the drive wheel (20) and is arranged so that the engagement movement of the coupling pawl (21) into the tooth portion (231) brings the coupling pawl (21) into contact with the end side contact surface (217).

Description

[Technical Field]

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

[0002] A belt retractor is used in a seat belt system for an automobile and serves to retract one end of a seat belt provided to restrain an occupant. The belt retractor is fastened to either 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 fastening purposes and a belt reel rotatably mounted within the frame, and can retract the seat belt onto the belt reel. The belt reel is spring-biased in the retracting direction via a spring, and a blocking device can block further retraction of the seat belt when a predetermined belt retraction acceleration is exceeded or when the vehicle decelerates. As a result, the occupant is restrained before a collision with the vehicle interior structure, preventing serious injury.

[0003] In order to reduce the load of a restrained occupant, a force limiting device has proven advantageous, which blocks the belt reel and allows a force-limited rotation of the belt reel in the direction of withdrawal when a predetermined belt withdrawal force is exceeded, and thus a force-limited forward movement of the occupant.Since the reduction in occupant load thereby permitted is directly related to the available forward movement path, it has also proven advantageous to tighten the existing belt slack in the seat belt by means of a belt tensioner before the force limiting device is activated, in order to increase the available forward movement path and couple the occupant to the deceleration of the vehicle as soon as possible.

[0004] Belt tensioners are distinguished between reversible and non-reversible or performance belt tensioners. Reversible belt tensioners have a lower tensioning capacity of approximately 100-800 N and function to tighten the belt slack in critical situations in preparation for a possible subsequent accident. If no accident occurs, the seat belt is then loosened again. Electric motors with particularly good reversible control 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 is no longer unavoidable, i.e., in the early stages of an accident. Therefore, irreversible belt tensioners are always activated after reversible belt tensioners. Pyrotechnic drives that cannot be reactivated after activation have proven to be irreversible belt tensioner drives, and therefore, if they are activated, the entire seat belt system with the irreversible belt tensioner must be replaced.

[0005] In this case, the belt tensioner can engage different positions on the seat belt, for example, the belt buckle, the end attachment, or even the belt retractor. When the belt tensioner is used in a belt retractor, upon activation, the belt tensioner abruptly drives the belt reel in the retracting direction, thereby tightening any existing belt slack in the seat belt. For the purposes of this invention, the term "belt tensioner" should be understood to mean only the belt tensioner arranged on the belt retractor and driving the belt reel. Since the belt reel must essentially be able to rotate freely for buckling and unbuckling in normal use, the drive of both reversible and irreversible belt tensioners is connected to the belt reel via a coupling only in the event of activation. The coupling should be designed to never establish an unintended rotational connection, so that normal use of the belt retractor is hindered due to the resulting interference with the rotational movement of the belt reel.

[0006] Since the reversible belt tensioner will be deactivated again if the accident does not subsequently occur and the belt retractor is again in normal use, the coupling of the reversible belt tensioner must likewise be of reversible design. Furthermore, if an accident subsequently occurs and the irreversible belt tensioner is activated, the coupling of the reversible belt tensioner must be intentionally disengaged so that the still-engaged coupling of the reversible belt tensioner does not interfere with the drive movement of the irreversible belt tensioner.

[0007] Furthermore, the couplings 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, whereby the motion of the coupling is actively controlled by the starting motion of the drive.

[0008] Thus, on the one hand, the coupling automatically performs a coupling movement when the drive is actuated, but in other situations it is required that no coupling movement is intentionally performed in order to prevent an undesired coupling connection.

[0009] For example, the applicant's document DE 100 59 227 (C1) 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 being slidably mounted on the drive wheel and engaging with the internal toothing of a clutch bell which is rotatably connected to the belt shaft to establish the coupling connection.

[0010] A coupling for a belt tensioner is also known from DE10 2014 009 038(B4), which has two coupling pawls attached to a drive wheel, called an input element, which engage with external toothing of an output element connected to a belt reel to establish the coupling connection.To control the movement of the coupling elements, a control element is provided which is coupled to the inertial mass and which is provided with an input control geometry and an output control geometry for controlling the movement of the coupling pawls.

[0011] Against this background, the invention is based on the object of providing a belt retractor of the general type in which the transmission of the drive movement of the drive wheel to the belt shaft is further improved.

[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 taken from the dependent claims, the figures and the associated description.

[0013] According to the basic concept of the invention, a radially extending force transmission surface is provided on the drive wheel, which is arranged in such a way that as a result of the engagement movement with the toothing the coupling pawl rests on it with its end face contact surface, and in the engagement position the drive wheel drives the coupling pawl onto the toothing fixed to the belt reel, applying a compressive force in the circumferential direction of the drive wheel and transmitting a rotational movement to the belt reel via the force transmission surface.

[0014] Due to the radially extending force transmission surfaces provided on the drive wheel and the drive of the coupling pawls realized thereon, the drive force is transmitted to the belt reel by the engagement of the coupling pawls with the teeth fixedly connected to the belt reel so that the drive force is transmitted more quickly and therefore more directly from the drive wheel to the coupling pawls and the belt reel. At the same time, the bearing forces to be absorbed by the coupling pawls on the drive wheel in the rotary joint are reduced by dividing the bearing forces between the rotary joint and the radially extending force transmission surfaces. Ideally, 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 fixedly arranged on the belt reel, the drive torque can be transmitted even without the coupling pawls being supported by a load.

[0015] It is further proposed that the force transmission surfaces be inclined radially relative to the rotation axis of the drive wheel, and that this inclination be aligned with the teeth of the toothing fixed to the belt reel. Due to the proposed alignment of the force transmission surfaces with the alignment of the teeth of the toothing fixed to 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 to 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.

[0016] It is further 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 reversible belt tensioning and belt reel drive. 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.

[0017] It is further proposed that at least one first tooth is provided on the coupling pawl, with which the coupling pawl engages in the engagement position with the toothing fixed to the belt reel, so that the coupling pawl has a contour adapted to the toothing fixed to the belt reel, and the toothing geometry of the at least one first tooth on its tooth flank corresponds to the tooth flank of the toothing fixed to the belt reel.

[0018] It is further proposed that the end faces of the teeth facing the toothing part fixed to the belt reel are oriented so that the angle between the end faces of the teeth and the radially outward end faces of the teeth of the toothing part is less than 30 degrees. The proposed alignment of the end faces of the teeth with respect to the end faces of the teeth of the toothing part fixed to the belt reel ensures that in case of tooth-to-tooth contact, the teeth will slide off the teeth of the toothing part fixed to the belt reel with very low compressive force without jamming themselves.

[0019] It is further proposed that at least one second tooth is provided, the first or second tooth being designed to form an enlarged catch tooth, with which the coupling pawl is first brought into engagement with the tooth fixed to the belt reel during the engagement movement, which first engages with the tooth fixed to the belt reel, thereby causing a pre-alignment of the coupling pawl with the toothing fixed to the belt reel, so that the further tooth engages with the toothing fixed to the belt reel in a defined alignment, without itself being blocked in case of tooth-to-tooth contact.

[0020] In this case, the catch tooth is preferably formed by a first tooth adjacent to the end contact surface, so that the coupling pawl is pulled into the toothing fixed to the belt reel starting from the end facing the end contact surface.

[0021] It is further 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 resting on the first control contour with the first control pin, the first control contour defining through its shape the path of the engagement movement of the coupling pawl in the toothing fixed to the belt reel by the first control pin sliding on it.

[0022] It is further proposed that the first control profile has a circumferentially oriented blocking portion and that the first control pin is arranged on the coupling pawl in such a way that it is arranged radially inward relative to the blocking portion in the engagement position of the coupling pawl, by means of the blocking portion of the first control profile the coupling pawl is blocked against a radially outward control movement from the toothing fixed to the belt reel during toothing engagement during reversible pretensioning.

[0023] It is further proposed that the first control profile be formed by a spring arm, one end of which is fixed to the control element, and that the first control pin slides on the spring arm from its fixed end to its free end during the engagement movement of the coupling pawl. The design of the first control profile as a spring arm and its proposed arrangement allow the control pin and the coupling pawl to perform a small radial movement relative to the first control profile during the engagement movement, which prevents impediments to the movement due to geometric inaccuracies or differences in frictional forces.

[0024] It is further proposed to provide a second control contour 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 individual shape of the second control contour.

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

[0026] It is further proposed to provide the control element with a blocking contour which forms a stop for the coupling pawl in the engagement position, the blocking contour defining the end position of the coupling pawl after completion of the engagement movement, and thereby limiting further differential movement of the control contour relative to the coupling pawl.

[0027] It is further proposed that the blocking profile has a radially oriented first blocking surface and a circumferentially oriented second blocking surface, the first blocking surface forming a stop, the coupling pawl being biased radially outward during rotational movement of the teeth in the seat belt retraction direction, and the control element being biased for relative movement by a compressive force exerted on a spring arm by a first control pin, while the second control pin slides from the first blocking surface to the second blocking surface, the second blocking surface blocking the coupling pawl from pivoting radially inward toward the teeth fixed to the belt reel. The proposed solution means that when the irreversible belt tensioner is activated and the belt reel rotates in the retraction direction, the coupling pawl is automatically pushed out of the engagement position, releasing the coupling connection. Additionally, the coupling pawl is simultaneously blocked by a support on the second blocking surface against repeated engagement with the teeth fixed to the belt reel.

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

[0029] Furthermore, in this respect, it is proposed that the coupling pawl is pivotally mounted on a pivot bearing arranged at its end remote from the end face contact surface, during which 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 rotational motion of a reversible belt tensioner. [Figure 3] The drive wheel in engagement movement, the coupling pawl, and the teeth fixed to the belt reel. [Figure 4] a drive wheel in a disengaged position, a coupling pawl, and a tooth portion fixed to the belt reel. [Figure 5] a drive wheel in an engaged position, a coupling pawl, and a tooth portion fixed to the belt reel. [Figure 6] A drive wheel, a coupling pawl, and a tooth portion fixed to the belt reel are in a first contact position during the engagement movement. [Figure 7] The teeth of the first tooth during the engagement movement are in contact with the drive wheel, the coupling pawl, and the tooth portion fixed to the belt reel. [Figure 8] FIG. 10 is an enlarged view of the drive wheel, coupling pawl, and tooth portion fixed to the belt reel in the tooth-to-tooth contact position of the first tooth during the engagement movement. [Figure 9] During operation of the irreversible belt tensioner, the drive wheel, the coupling pawl, and the teeth fixed to the belt reel are in different positions. 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 retracting unit 4. The retracting 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 is activated in pre-accident situations to tighten the seat belt in preparation for a possible accident. The seat belt is tightened with a tension of 100-800N, which can be selected to various levels according to the vehicle manufacturer's specifications, or the tension can be designed to increase in stages according to various pre-accident specific criteria.

[0033] The irreversible belt tensioner 7 is only activated 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 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 fitted with a gear mechanism for transmitting the rotary drive movement of the electric motor to a drive wheel 20 .

[0035] The toothed ring 23 visible in Figure 2 is held rotatably fixed on the extension 8 of the belt reel 5. The toothed ring 23 has radially outer teeth which, in the fastened position of the toothed ring 23 on the extension 8, form teeth 231 fixed to the belt reel.

[0036] The housing part 25 shown in FIG. 2 is mounted 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 support opening of the drive wheel 20. Furthermore, a control element 22 is provided, which includes a ring spring 221 and a plate element 222 fixed via the ring spring 221, and the control element 22 is fixed by the ring spring 221 so as to frictionally engage with the axial extension 251. Furthermore, a coupling pawl 21 is provided, which is arcuate in shape and has a bearing pin 211 that protrudes on both sides at one end thereof. Furthermore, an annular cover disk 24 is provided, which has a bearing opening 241, in which the coupling pawl 21 is mounted on one side by the bearing pin 211, and which, on the other side, engages in a bearing opening of the drive wheel 20 (not shown). Thus, the coupling pawl 21 is mounted on both sides of the drive wheel 20 and the cover disk 24.

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

[0038] As can be seen in Figures 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 the radially inner edge side 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 the curved upper edge side of a protrusion protruding axially from the plate portion 222. In addition, as can be seen in Figure 5, an axially protruding blocking contour 225 having a first radially aligned blocking surface 226 and a second circumferentially aligned blocking surface 227 is provided on the plate portion 222. The coupling pawl 21 is provided with a first axially protruding control pin 212 and a second axially protruding control pin 213, which protrude axially from the side of the coupling pawl 21 and which, in the mounted position, faces the plate portion 222 of the control element 22. Conversely, the plate portion 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 pawl 21 on which the control pins 212 and 213 are arranged.

[0039] 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 in the toothed portion 231 fixed to the belt reel. As can be seen in FIG. 6, the first tooth 214 is enlarged, shaped, and aligned so that it first engages with the toothed portion 231 fixed to 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 most forward tooth of the coupling pawl 21. Therefore, the first tooth 214 is 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 to the belt reel, thereby pre-aligning the coupling pawl 21 with the toothed portion 231 fixed to the belt reel. The first tooth 214 therefore functions as a catch tooth. As the coupling pawl 21 is pre-aligned, it engages with the further teeth 215 and 216 in the toothing 231 fixed to the belt reel, and the engagement movement is not blocked by the tooth-to-tooth contact of the further teeth 215 and 216.

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

[0041] As can be seen in the enlarged view of Figure 8, the radially inner end surface of the first tooth 214 is shaped so that the end surface of the first tooth 214 forms an angle W of less than 30 degrees in the circumferential direction with respect to the end surface of the adjacent tooth of the toothed portion 231 fixed to the belt reel. Therefore, the first tooth 214 slides along the end surface of the tooth of the toothed portion 231 fixed to the belt reel without blocking the movement. After the first tooth 214 disengages, it engages with the next gap against the next tooth of the toothed portion 231 fixed to 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 pivoted to a disengaged position. Starting from this position, an engagement movement of the coupling pawl 21 is caused 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, and then, during a further rotational movement, the first control pin 212 of the coupling pawl 21 slides along this control section. By the first control pin 212 sliding along the control section 2232 of the first control contour 223, the coupling pawl 21 is forced to perform an engagement movement radially inward in the direction of the toothing 231 fixed to 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 the coupling pawl 21 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 its engagement movement, the coupling pawl 21 is further moved by the drive wheel 20 in the direction of arrow S on the force transmission surface 201 relative to 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. Together with the first blocking surface 226, the first blocking contour 225 thus 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 where the first control pin 212 is positioned radially inward relative to the blocking part 2231 of the first control contour 223. The coupling pawl 21 is therefore then secured against unintentional pivoting off from the toothing 231 fixed to the belt reel. Furthermore, in this engaged position seen in Figure 5, the coupling pawl 21, together with the teeth 214, 215 and 216, rests in a force-transmitting manner on the teeth of the toothing 231 fixed to the belt reel.

[0043] The force transmission surface 201 of the drive wheel 20 is inclined radially outward and forms an angle E1 of approximately 15 to 30 degrees with respect to the radial direction opposite the drive direction of the drive wheel 20 in the direction of arrow S. The end face contact surfaces of the coupling pawls 21 are aligned at the same angle E1 with respect to the radial direction in the engagement position of the coupling pawls and are 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 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 force transmission surface angle E1 and form angles E2-E4 of approximately 15-30 degrees opposite to the drive direction of the drive wheel 20 in the direction of arrow S, so that force vectors F1-F4 on the force transmission surface 201 are directed radially outward toward the end face contact surface 217, from the teeth of the toothing 231 fixed to the belt reel to the teeth 214, 215, and 216. The angles E1-E4 do not have to be identical; they simply need to be in the same radial direction and inclined relative 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 prevents the tooth flanks and the end face contact surface 217 from sliding 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 pawl 21 in the adjacent position in Figure 3. The coupling pawl 21 rests flat on the force transmission surface 201 with its end face contact surface 217.

[0044] The drive force is therefore transmitted directly from the drive wheel 20 via the coupling pawl 21 to the teeth 231 of the toothed ring 23 fixed to 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 is aligned so 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 bearing of the coupling pawl 21 is not placed in the force transmission path from the force transmission surface 201 to the teeth 231 fixed to the belt reel via the contact surface 217, and the coupling pawl 21 introduces the torque applied by the force transmission surface 201 into the teeth 231 fixed to the belt reel without stressing the bearing of the coupling pawl 21.

[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 positioned 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 during further rotation of the drive wheel 20 in the direction of arrow A, the coupling pawl 21 slides out of it and is pulled radially outward until it is again positioned in the disengaged position shown 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 to 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 driving 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 urged radially outward by the teeth of the toothed ring 231 fixed to the belt reel, which slides on the teeth 214, 215 and 216, so that the first control pin 212 moves the spring arm 228 radially outward and the second control pin 213 moves radially outward on the first blocking surface 226 of the blocking contour 225, as can be seen in the central view of FIG. 9. The deformation of the spring arm 228 exerts a circumferential force on the plate element 222 of the control element 22, causing it to move in the direction of arrow R as soon as the second control pin 213 no longer abuts laterally against the first blocking surface 226. By moving the plate element 222, it moves into a position where it, together with the second blocking surface 227 of the blocking contour 225, supports the second control pin 213 radially inward. Furthermore, the first control pin 212 overcomes the spring arm 228, causing it to 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.

[0047] The coupling pawl 21 is then irreversibly blocked against pivotal movement in the reverse 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 in 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), which, when activated, drives the belt reel (5) in the winding direction via the drive wheel (20), - An actively controlled tensioner coupling that transmits the driving motion from the drive wheel (20) to the belt reel (5), - At least one coupling claw (21) attached to the drive wheel (20), the coupling claw (21) is movable to engage and disengage with teeth (231) fixed to the belt reel in order to establish and disconnect 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 to the belt reel, Equipped with, - A radially extending force transmission surface (201) is provided on the drive wheel (20), and the coupling claw (21) is arranged to come into contact with the contact surface (217) by the engagement movement within the teeth (231) fixed to the belt reel. - The belt retractor (1) is characterized in that the drive wheel (20) applies a compressive force in the circumferential direction of the drive wheel (20) and drives the coupling claw (21) into the teeth (231) fixed to the belt reel in the engagement position in order to transmit rotational motion to the belt reel (5) via the force transmission surface (201).

2. - The belt retractor (1) according to claim 1, characterized in that the force transmission surface (201) has an inclination in the radial direction 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 to the belt reel.

3. - The belt retractor (1) according to claim 1, characterized in that the force transmission surface (201) is arranged such that the coupling claw (21) placed thereon in the engagement position does not come into contact with the first control contour (223).

4. - The belt retractor (1) according to claim 1, characterized in that the coupling claw (21) is provided with at least one first tooth (214), and the coupling claw (21) engages with the toothed portion (231) fixed to the belt reel by the first tooth (214) in the engagement position.

5. - The belt retractor (1) according to claim 4, characterized in that the end face of the first tooth (214) facing the tooth portion (231) fixed to the belt reel is oriented such that the angle (W) between the end face of the first tooth (214) and the radially outward-facing end face of the tooth of the tooth portion (231) fixed to the belt reel is less than 30 degrees.

6. - At least one second tooth (215, 216) is provided, - The belt retractor (1) according to claim 4, characterized in that the first teeth or the second teeth (214, 215, 216) are designed as enlarged catch teeth that first engage the coupling claw (21) with the teeth (231) fixed to the belt reel during the engagement movement.

7. - The belt retractor (1) according to claim 6, characterized in that the catch teeth are formed by the first teeth (214) adjacent to the contact surface (217).

8. - The belt retractor (1) according to claim 1, characterized in that a first control pin (212) is provided on the coupling claw (21), and the coupling claw slides together with the control pin on a first control contour (223) during engagement movement.

9. - The first control contour (223) has a blocking portion (2231) oriented in the circumferential direction, - The belt retractor (1) according to claim 8, characterized in that the first control pin (212) is positioned on the coupling claw (21) such that, at the engagement position of the coupling claw (21), the control pin is positioned radially inward with respect to the blocking portion (2231).

10. - The first control contour (223) is formed by a spring arm (228) with one end fixed to the control element (22), - The belt retractor (1) according to claim 8, characterized in that the first control pin (212) slides along the spring arm (228) from the fixed end toward the free end during the engagement movement of the coupling claw (21).

11. - The belt retractor (1) according to claim 1, characterized in that a second control contour (224) for controlling the disengagement movement of the coupling claw (21) is provided on the control element (22).

12. - The belt retractor (1) according to claim 11, characterized in that a second control pin (213) is provided on the coupling claw (21), and during engagement movement, the coupling claw slides together with the control pin on the second control contour (224).

13. - The belt retractor (1) according to claim 1, characterized in that a blocking contour (225) that forms a stop portion for the coupling claw (21) at the engagement position is provided on the control element (22).

14. - The blocking contour (225) has a first blocking surface (226) oriented in the radial direction and a second blocking surface (227) oriented in the circumferential direction. - The first blocking surface (226) forms the stopping portion, - The coupling claw (21) is biased radially outward in the winding direction when the teeth (231) fixed to the belt reel rotate. -Therefore, the control element (22) is biased 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) slides from the first blocking surface (226) onto the second blocking surface (227), - The belt retractor (1) according to claim 13, characterized in that the second blocking surface (227) blocks the coupling claw (21) from radially inward pivoting motion into the teeth (231) fixed to the belt reel.

15. - The belt retractor (1) according to claim 1, characterized in that the coupling claw (21) has a curved bow shape, and the shorter curved side portion (219) is arranged to face the teeth portion (231) fixed to the belt reel.

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

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