Belt retractor

Abstract

The present invention relates to a belt retractor comprising a belt shaft (5) rotatably mounted on a frame (1) and around which a safety belt can be wound, and a force limiting unit (61) which, when activated, allows rotational movement of the belt shaft (5) in the extension direction of the safety belt, the force limiting unit (61) comprising an electric motor (4) and a first blocking device, the first blocking device being configured to release and reblock in a repeated sequence the rotational movement of the belt shaft (5) in the extension direction in a manner actuated by the operation of the electric motor (4).

Description

[Technical Field]

[0001] The invention relates to a belt retractor having the features of the preamble of claim 1 .

[0002] The belt retractor has as its basic components a load-bearing frame and a belt reel which is rotatably mounted in the frame and onto which the safety belt can be wound. The frame not only serves to mount the belt reel but also to fasten the belt retractor to the seat structure or vehicle structure, and for this purpose the frame is made of steel plate of corresponding thickness bent into a U-shaped frame.

[0003] Vehicle seats with integrated safety belt systems are known, for example for use as front seats in convertibles, with at least the belt retractor of the safety belt system fastened in the seat back of the vehicle. In this case, due to the lack of load-bearing B-pillars and for reasons of access to the rear seats or distance from the rear vehicle structure, the belt retractor is preferably integrated in the seat back of the vehicle, and therefore must also be designed to absorb the pulling forces acting in the event of restraint. The belt retractor itself has all the basic components of a standard belt retractor, and is only equipped with various additional subassemblies, such as a self-aligning inertial sensor, specifically provided for installation in the seat back.

[0004] In the basic design of a vehicle seat, the vehicle seat has a seat structure made up of several load-bearing structural parts that serve to fasten the vehicle seat to the vehicle structure, the seat structure is equipped with springs and cushioning to improve seating comfort, and the seat structure is also used for fastening further components such as various seat adjustment mechanisms with associated electric motors, as well as further components such as heating devices, sensors, displays, and headrests.

[0005] In modern vehicles with automated driving systems, there is an increasing demand for greater adjustability of the vehicle seat in various orientations and positions within the vehicle interior so that the vehicle occupants can use the freedom afforded by automated driving, for example, for more meaningful communication with other occupants, for longer and more intensive rest periods, or even for work, and can orient the vehicle seat accordingly. As a result, the safety belt device, and in particular the belt retractor, is no longer fastened to the vehicle structure as before, but rather needs to be fastened to the vehicle seat with all its components, i.e., the belt retractor and the belt buckle, as is already the case, for example, in the case of convertible front seats.

[0006] Furthermore, in modern safety belt systems, the belt retractor is provided with an electric motor, which drives the belt shaft when actuated, for example, to reversibly tighten the belt in the retracting direction. The electric motor is also fastened to a frame and arranged transversely of the belt shaft, with the drive shaft oriented parallel to the belt shaft's rotation axis. It is also known to provide a gear mechanism between the belt shaft and the electric motor, which is used to convert the rotational speed of the electric motor into a predetermined rotational speed of the belt shaft. The use of a gear mechanism makes it possible to use an electric motor that is as compact as possible and has a high rotational speed, while still applying a relatively high torque to the belt shaft. However, belt retractors using compact electric motors made possible by the gear mechanism have been manufactured that require increased installation space overall. Such belt retractors are known, for example, from WO 03 / 099619 A2.

[0007] If the belt shaft is driven at different rotational speeds and torques, further gear stages must be provided, which further increases the installation space requirements. Such a belt retractor is known, for example, from DE 19927731 (C2).

[0008] It is also known to provide a belt retractor with a force-limiting unit that allows for force-limited forward displacement of the occupant, reducing the load on the occupant before it is absorbed by the airbag. In particular, a steel torsion rod, with one end connected in a rotationally fixed manner to a portion that can be blocked in a fixed relationship with the vehicle and the other end connected to the belt shaft, has proven effective as a force-limiting unit. During torsion bar activation, the torsion bar plastically twists about its longitudinal axis, thus intentionally dissipating energy. In this case, the force-limiting level or force-limiting characteristics are determined by the torsion bar's resistance to plastic deformation, which varies depending on the torsion bar's material and diameter. The torsion bar provides a constant force-limiting level and is activated only when its plastic deformation limit is exceeded. For example, if the tension of a belt for restraining a small child is not large enough to exceed the plastic deformation resistance, the occupant, or in this case, the child, will not experience force-limited forward displacement. In this case, the occupant does not utilize the available forward displacement path for restraint within the vehicle cabin, and instead is restrained with a greater load on the occupant than would actually be possible if the available forward displacement path were fully utilized.

[0009] Furthermore, from German Patent No. 102005016822 (B3) a frequency-controlled force-limiting unit is known that facilitates force-limited belt extension by means of an oscillating mass system. The advantage of this force-limiting unit can be seen in the fact that the force-limited belt extension operates independently of the tensile force acting on the belt, and the forward displacement path utilized to reduce the load on the occupant is also independent of the severity of the accident. Therefore, it is ideal to always utilize the maximum forward displacement path for the occupant, thereby maximizing the reduction in the load on the occupant. The force-limiting characteristics of this force-limiting unit are determined by the design of the oscillating mass system.

[0010] Both the torsion bar force limiting unit and the frequency controlled force limiting unit are actuated by the tension force acting on the belt and have invariant force limiting characteristics that are determined solely by their design.

[0011] Against this background, it is an object of the present invention to provide a belt retractor having a force limiting unit intended to allow improved and controlled belt extension to reduce the load on the occupant.

[0012] According to the invention, a belt retractor is proposed to achieve that object having the features of claim 1. Further advantageous developments can be taken from the dependent claims, the figures and the associated description.

[0013] According to the basic idea of the invention, it is proposed that the force limiting unit of the belt retractor comprises an electric motor and a first blocking device, the first blocking device being designed to release and reblock in a repeated sequence the rotational movement of the belt shaft in the extension direction by activating the electric motor.

[0014] The advantage of the proposed solution lies in the fact that the force-limiting unit of the belt retractor has a controllable electric motor, and the first blocking device is purposely configured to enable force-limited belt extension triggered by the activation of the electric motor, releasing and re-blocking the rotational movement of the belt shaft in the extension direction in a repeated sequence. Thus, the start and end of the belt extension movement can be controlled independently of the tension acting on the belt. In this case, the rotational movement of the belt shaft before the electric motor is activated is blocked by the blocking device located in the blocking position and is only enabled by the activation of the electric motor. The electric motor can also be considered here as a trigger for the force-limited belt extension movement. As a result of the brief release of the first blocking device, under the tension applied by the occupant when restrained in an accident, the belt is extended in a very short time until the next blocking of the first blocking device, and the occupant is displaced forward with reduced load before the blocking device stops the forward displacement again, and the process is repeated. The first blocking device is designed so that the time interval between unlocking and the next blocking is between 0.01 ms and 0.05 ms, so that the belt is gradually extended with very short repeated extension movements, but because the time range is so short, the occupant will not notice it.

[0015] It is further proposed that, upon activation of the electric motor, the first blocking device can be moved from a position blocking the belt shaft to a position releasing the belt shaft, and that the first blocking device automatically blocks again as a result of allowing rotational movement of the belt shaft in the direction of extension after a predetermined angle of rotation of the belt shaft. According to the proposed development, the electric motor is used to trigger the unlocking operation of the first blocking device, thus allowing the intended belt extension movement by the released belt shaft. The subsequent extension movement can be caused, for example, by a pulling force applied to the belt by the occupant. The electric motor does not need to contribute here. However, it is not excluded that the electric motor can be actively used to influence the extension movement. Since the first blocking device is further configured to automatically block again after a predetermined angle of rotation of the belt shaft, the rotational movement of the belt shaft in the direction of extension is then automatically stopped again before the belt shaft is released and blocked again in a repeating process.

[0016] In this case, triggering of the unlocking operation of the first blocking device can be realized particularly easily and with a compact design by providing an unlocking ring driven by an electric motor and having a control contour, and forming the first blocking device by at least one blocking element abutting against the control contour. Due to the shape of the control contour, the unlocking ring controls the triggering and the path or possibility of movement of the blocking element abutting against the unlocking ring by its movement triggered by the drive via the electric motor. In this case, the control contour is designed by its shape to press the blocking element into a blocking position over a certain area during movement and to intentionally release the blocking element again in a certain area, so that the blocking element can move from the blocking position to the release position and vice versa during its relative movement with respect to the unlocking ring, or is forced to move by the shape of the control contour.

[0017] Such a shape of the control contour can be realized, for example, by a ramp structure including a number of ramps corresponding to the number of blocking elements and recesses arranged between the ramps, with the blocking elements abutting the recesses alternately in the blocking and release positions, in which case the blocking elements are unlocked and blocked by a relative movement of the blocking element(s) relative to the control contour, which can be triggered by a drive of the unlocking ring via an electric motor for the blocking element(s) and then formed by a combination of the movement of the unlocking ring and the movement of the blocking element(s).

[0018] It is further proposed that a rotation direction reversing gear is provided that is rotationally connected to the belt shaft via a first portion, and that a first blocking device is disposed between the first portion of the rotation direction reversing gear and a second portion of the rotation direction reversing gear that is driven by the rotation direction reversing gear in a direction opposite to the rotation direction of the belt shaft. As a result of the proposed development, it can be ensured that the portions blocked relative to one another via the first blocking device always have a relative movement relative to one another, which can be used to automatically block the first blocking device. Furthermore, this relative movement is further increased by the rotation direction reversing gear and the resulting different rotation directions of the blocked portions relative to one another. Due to this increased relative movement, the rotation angle of the first portion, and therefore the rotation angle of the belt shaft, can also be reduced after the first blocking device is blocked again.

[0019] The rotation direction reversing gear can be preferably designed so that the second part performs a rotational movement relative to the first part that is converted to a higher rotational speed by the rotation direction reversing gear. This can further increase the relative rotational movement available for blocking the first blocking device, thereby shortening the rotation angle of the belt shaft at which the belt shaft is subsequently blocked again. This is because the second part performs an increased movement relative to the movement of the first part, and therefore performs the majority of the relative movement. Furthermore, the rotation direction reversing gear can be designed as a gear mechanism that reduces the rotational speed of the electric motor to a lower rotational speed of the belt shaft in its actual functional direction for tensioning the belt. Furthermore, the conversion of the rotational movement can be advantageous in that the first blocking device can be realized with a relatively small motor torque.

[0020] This allows for a particularly compact design of the belt retractor, since the rotation-reversing gear is formed by the planet gear and the reversal of the rotation direction at the rotation-reversing gear is achieved by the planet gear's planet carrier, which is blocked by a second blocking device relative to the frame of the belt retractor. The advantage of this solution is that the planet gear basically has a very compact design and enables a high transmission ratio. Furthermore, the planet gear can have a very simple structural design as the rotation-reversing gear, since the planet carrier is blocked relative to the frame of the belt retractor. Therefore, in principle, the planet gear can be used to perform further functions, such as reversible pretensioning for converting the rotational movement of the drive part without blocking the planet carrier, for example, without reversing the rotational direction of the rotational movement.

[0021] It is further proposed that the first or second part of the rotation direction reversing gear has a blocking contour against which the first blocking device abuts in the blocking position, forming a form-fit connection with respect to the direction of rotation of the two parts relative to each other and preventing further rotational movement of the second part relative to the first part. The blocking contour is arranged in such a way that during rotational movement of the first part or the belt shaft in the extension direction of the belt, the first blocking device automatically rests on it and blocks further rotational movement.

[0022] It is further proposed that the first part is formed by a tubular axial extension, which is non-rotatably connected to the belt shaft and forms the housing of the rotation direction reversing gear. The first part actually forms a tubular extension of the belt shaft in the axial direction, which tubular extension forms a shoulder for blocking the belt shaft and at the same time, due to its shape, serves as the housing for the rotation direction reversing gear.

[0023] In this case, the blocking contour can be formed by a ramp, preferably oriented in the circumferential direction and located inside the annular extension, against which the blocking element abuts in the blocking position. The proposed shape has the advantage that, on the one hand, the ramp allows for active retraction of the first part when the first blocking device is in the blocking position. On the other hand, due to their ramp, the ramp allows for automatic displacement of the blocking device from the blocking position to the release position when the first blocking device is no longer being pushed toward the blocking position by the control contour of the unlocking ring. Thus, the blocking contour not only blocks the first blocking device, but also triggers the unlocking movement when the first blocking device is released.

[0024] It is further proposed that the unlocking ring is spring-loaded against the belt shaft via a spring. As a result of the proposed solution, the unlocking ring is elastically connected to and held on the belt shaft, thereby rotating with the belt shaft and, as a result, being held by the spring in a position relative to the belt shaft which pushes the blocking device into a blocking position.

[0025] It is further proposed that the belt shaft is loaded in the direction of retraction of the safety belt by a main spring fixedly supported on the frame, the spring force of the main spring being smaller than the spring that loads the unlocking ring. As a result of the proposed development, the electric motor can also be used to realize comfort functions by additionally acting on the belt shaft parallel to the main spring when the safety belt is worn, thereby increasing the retraction force acting on the belt shaft, for example for light driving, or reducing the retraction force acting on the safety belt so that the occupant is less aware of the safety belt. Furthermore, the safety belt can also be retracted into a parking position after unbuckling.

[0026] The present invention will be described below using preferred embodiments with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a belt retractor according to the present invention in two representations: with the frame attached and in a partially disassembled state. [Figure 2] 1 is a belt retractor according to the present invention with the individual assemblies disassembled. [Figure 3] 1 is an exploded view of a belt retractor according to the present invention without a frame. [Figure 4] 1 is an exploded view of a planetary gear and force-limiting unit of a belt retractor according to the present invention without an electric motor. [Figure 5] 1 is a cross-sectional view of a belt retractor according to the present invention. [Figure 6] FIG. 10 is a cutaway view of a planetary gear with a force-limiting unit as an assembly. [Figure 7] The assembly of the force limiting unit is shown in a first exploded view, the housing of the gear mechanism. [Figure 8] Assembly of the force limiting unit is shown in a second exploded view, the housing of the gear mechanism. [Figure 9] 10A and 10B are enlarged cross-sectional views of a planetary gear with a force-limiting unit having different cross-sectional directions. [Figure 10] 10 is a cross-sectional view of FIG. 9 in cross-sectional direction AA with the coupling disposed between the housing and the gear mechanism during winding into a parking position. [Figure 11] 10 is a cross-sectional view of FIG. 9 in cross-sectional directions BB, CC and DD before activation of the force-limiting unit. [Figure 12] 10 is a cross-sectional view of FIG. 9 in cross-sectional directions BB, CC and DD during activation of the force-limiting unit in a first position. [Figure 13] 10 is a cross-sectional view of FIG. 9 in cross-sectional directions BB, CC and DD during activation of the force-limiting unit in a second position. [Figure 14] 10A and 10B are cross-sectional views of FIG. 9 in cross-sectional directions BB, CC and DD during operation of the safety belt reminder. [Figure 15] 10 is a drive wheel with a spring and two spring-loaded pawls with an unlocking ring as an assembly according to a second embodiment. [Figure 16] The unlocking ring of FIG. 15 is shown in exploded view, as is the drive wheel. [Figure 17] FIG. 10 is a cross-sectional view of the second exemplary embodiment through the drive wheel in cross-sectional direction DD during winding into a parking position. [Figure 18] 16A and 16B are cross-sectional views of the belt retractor with the drive wheel according to FIG. 15 in the cross-sectional directions BB, CC and DD at the initial stage of actuation of the reversible belt tightening. [Figure 19]16A and 16B are cross-sectional views of the belt retractor with the drive wheel according to FIG. 15 in the cross-sectional directions BB, CC and DD at the later stage of the operation of the reversible belt tensioning. [Figure 20] 16A and 16B are cross-sectional views of the belt retractor with the drive wheel according to FIG. 15 in the cross-sectional directions BB, CC and DD at the initial stage of actuation of the force-limiting unit. [Figure 21] 16A and 16B are cross-sectional views of the belt retractor with the drive wheel according to FIG. 15 in the cross-sectional directions BB, CC and DD in the next stages of actuation of the force-limiting unit. [Figure 22] 16A and 16B are cross-sectional views of the belt retractor with the drive wheel according to FIG. 15 in the cross-sectional directions BB, CC, and DD during activation of the safety belt reminder.

[0028] 1 and 2 show a belt retractor according to the present invention, which has an elongated tubular frame 1 composed of two housing shells 3. Its basic design is rectangular in cross section, except for rounded and some inclined sections. Frame 1 has a slot 2 through which a safety belt (not shown) is propelled onto a vehicle occupant restrained by the safety belt. One of the housing shells 3 is omitted in the lower illustrations of FIGS. 1 and 2 to allow a better view of the belt retractor assembly. In its elongated form, the belt retractor is specifically designed to be placed in a vehicle seat. Due to the coaxial arrangement of the assembly, as described below, the belt retractor has the smallest possible cross-sectional height and width, thereby enabling it to be placed in the narrow cavity of the vehicle seat. Frame 1 is divided by a number of webs 7, which are closed at its ends and serve to secure frame 1 on the one hand and to mount or hold the assembly on the other.

[0029] The belt retractor has a belt shaft 5 around which a safety belt (not shown) can be wound. Furthermore, a spring cassette 9 is attached to the outside of the web 7 on the right side of the figure and is connected to the right side of the belt shaft 5 in the figure, as will be explained in more detail below. The belt shaft 5 is further connected to a gear mechanism 6 on its left side and is attached to the further web 7 via the gear mechanism 6. Furthermore, a locking unit 8 and an electric motor 4 are arranged coaxially with the belt shaft 5 and the gear mechanism 6. During normal operation of the belt retractor, i.e., when the safety belt is being fastened, worn, or unfastened, and the electric motor 4 is not activated, the assembly consisting of the belt shaft 5 and the gear mechanism 6 forms an assembly pretensioned in the winding direction by a main spring 91 of the spring cassette 9, which can be seen in FIG. 3 . Furthermore, the assembly consisting of the belt shaft 5 and the gear mechanism 6 can be blocked in the extension direction via the locking unit 8 when predetermined limits of belt extension acceleration and / or vehicle deceleration are exceeded.

[0030] FIG. 3 shows an exploded view of the belt retractor with its individual components, excluding the frame 1. Furthermore, the belt retractor can be seen in a cross-sectional view with one of the housing shells 3 in FIG. 5. The spring cassette 9 includes a housing 90, at whose outer end a main spring 91 is located and fastened. The open side of the housing 90 is closed by a housing cover 92 so that the spring cassette 9 can be prefabricated as an assembly and fastened to the right side and outside of the first web 7 via the housing 90. The belt shaft 5 has a two-part structure with a belt shaft body 50 and an end radial flange 52 connected to each other via a torsion bar 51. The torsion bar 51 is designed with a very high force limit level, e.g., 7 or 9 kN or more, and serves here only as overload protection, so it is not activated during normal use or in the event of an accident. If overload protection is omitted, the torsion bar 51 can also be omitted; in either case, it is irrelevant to the functionality enabled by the electric motor 4. Furthermore, the belt shaft body 50 protrudes into the spring cassette 9 by an extension and is connected to the main spring 91 via a spring heart.

[0031] A gear mechanism 6 is arranged on the left side of the belt shaft 5 and is connected in a rotationally fixed manner to the radial flange 52 of the belt shaft 5 by means of a gear mechanism housing 60 via a bayonet connection. The bayonet connection is realized here by correspondingly shaped fingers 521 on the radial flange 52 and recesses 603 on the gear mechanism housing 60, which are of corresponding shape and can be seen in Figure 4. The gear mechanism 6 comprises a planetary gear 62, a force-limiting unit 61, which will be explained in more detail below, a drive wheel 63 connected in a rotationally fixed manner to the drive shaft 41 of the electric motor 4, and a plurality of spring-loaded blocking parts 64, which can be seen, for example, in Figure 4.

[0032] The assembly consisting of the gear mechanism 6 and the belt shaft 5 is mounted on the second web 7 on its left side and extends through an opening in the second web 7, which has internal teeth. A third web 7, on which the electric motor 4 is mounted, is provided to form an intermediate space. The locking unit 8 is arranged in the intermediate space between the second and third webs 7. The locking unit 8 includes an electrically actuable actuator 82 mounted on the same web 7 to which the electric motor 4 is also fastened. The locking unit 8 further includes a control disk 80 with external teeth and rotatably mounted on an extension of the gear mechanism 6, and a first blocking pawl 81 that can be actuated by a belt extension acceleration sensor. The control disk 80 includes a control contour in which a second blocking pawl 6211 engages a control pin, which is mounted on the first planet carrier 621a, which will be described in more detail below. The second blocking pawl 6211 here forms a second blocking device, the function of which will be described in more detail below.

[0033] When the locking unit 8 is activated, the actuator 82 is energized, deflecting its lever. As a result, the lever of the actuator 82 is directed toward the tooth of the control disk 80, which is then stopped relative to the belt shaft 5 in connection with further rotational movement in the direction of safety belt extension, displacing the second blocking pawl 6211, which then engages with the internal tooth 71 of the web 7, thereby blocking the belt shaft 5 in the direction of extension. Furthermore, the locking unit 8 is provided with an AC blocking pawl 81, which, once a predetermined belt extension acceleration is exceeded, is directed toward the tooth, thereby blocking the control disk 8 from further rotational movement in the direction of belt extension, thereby displacing the second blocking pawl 6211 in the same direction. Finally, the fourth and final web 7 closes and supports the frame 1 on its left side and is provided on the left side of the belt retractor. However, the fourth web 7 can also be used additionally for the additional mounting of an electric motor 4.

[0034] 4 shows the gear mechanism 6 in an enlarged exploded view. The planetary gear 62 comprises a first planet carrier 621a with a plurality of rotatably mounted first planet gears 622a and a pivotally mounted blocking pawl 6211 forming a second blocking device. The planetary gear 62 further comprises a second planet carrier 621b with a sun gear on one side that meshes radially inward with the first planet gears 622a of the first planet carrier 621a and a plurality of rotatably mounted second planet gears 622b on the other side. An internally toothed ring gear 623 is further provided with a sun gear on one side that meshes radially inward with the second planet gears 622b of the second planet carrier 621b. A further third set of planetary gears 622 c rotatably mounted on pins 618 protruding axially from the carrier part 612 of the force-limiting unit 61 engages the internal teeth of the ring gear 623 .

[0035] The first planet gear 622a of the first planet carrier 621a meshes with the internal teeth 601 of the housing 60, thereby establishing a connection of the belt shaft 5 to the planet gear 62. The planet gear 62 further comprises a gear shaft 624, which is rotatably mounted on the drive shaft 41 of the electric motor 4 and which at its first end radially inwardly engages with first teeth 625 of the teeth of the third planet gear 622c of the planet gear stage of the planet gear 62 on the right side of the figure. The gear shaft 624 further has second helical teeth 627 in the center with a larger diameter, a ring portion 628 with a smooth surface arranged adjacent to the second helical teeth 627, and a third similar helical teeth 626 at its second end.

[0036] The force-limiting unit 61 comprises an unlocking ring 611 having a radially outwardly directed control contour 616 provided on one side of an axially protruding annular flange and an annular flange protruding on the other side with radially directed internal teeth 617. The unlocking ring 611 is connected to a first end 6152 of a spring 615 visible in FIG. 6 , which is connected at its second end 6151 to the housing 60 of the gear mechanism 6 and, through it, to the belt shaft 5. The force-limiting unit 61 further comprises an annular carrier part 612 having an axially protruding pin 618 on which a third planetary gear 622c of the final planetary stage of the planetary gear 62 shown in the figure is rotatably mounted. The carrier part 612 further comprises a plurality of slot-shaped radially directed recesses 614, in each of which a plate-shaped block element 613 is radially displaceably received.

[0037] 7 and 8 show the carrier part 612 with the gear shaft 624 inserted. The gear shaft 624 protrudes axially from the carrier part 612 with a first end and first teeth 625 disposed thereon, which engage with the first teeth 625 between the right side of the planetary gear 62 and the third planetary gear 622c of the third planetary gear stage. The second teeth 627 are designed in terms of diameter, width, and location on the gear shaft 624 to be disposed within the opening in the carrier part 612. Two spring-loaded parking pawls 629 are also pivotally mounted in the opening in the carrier part 612, and the spring load urges the parking pawls 629 into engagement with the second helical teeth 627.

[0038] The unlocking ring 611 has, on its side facing the carrier part 612, an annular flange on which is arranged a control contour 616 formed by alternating inclined portions 6161 and recesses 6162. Furthermore, the unlocking ring 611 is provided on its radially outer side with regularly arranged cutouts 6111 and one or more openings 6112 in a radial web arranged between the cutouts 6111, and the spring 615 is fixed with its first end 6152 in one of the openings 6112. The spring 615 is designed as an annular spring and is designed to be substantially stronger in terms of spring force than the main spring 91 in the spring cassette 9. Furthermore, the spring 615 is dimensioned and connected to the unlocking ring 611 and the housing 60 so as to fix the unlocking ring 611 in a position in which, in an unloaded state, i.e. in an installed state, the blocking element 613 is supported radially inward by the inclined portion 6161 of the control contour 616 of the unlocking ring 611 before the electric motor 4 is activated.

[0039] The drive wheel 63 has a central axial opening with internal toothing 631, and the electric motor 4 is connected in a rotationally fixed manner to its drive shaft 41 (shown in FIG. 3 ) via a toothed end 42. The drive wheel 63 and the drive shaft 41 thus form a rotationally fixed connection. An annular flange 635 is provided on the drive wheel 63, protruding axially toward the unlocking ring 611, and is a carrier of two radially arranged, radially inwardly protruding, pivotally mounted first pawls 632 and two radially arranged, radially outwardly protruding, pivotally mounted second pawls 633. The first pawls 632 and the second pawls 633 are spring-loaded in a driven position away from the annular flange 635 by two spring plates 634 held by the annular flange 635. This forces the radially inner first pawl 632 into the third external toothing 626 of the gear shaft 624. The first pawl 632 and the third tooth 626 are oriented such that a rotational movement of the drive wheel 63 in the retracting direction of the safety belt (arrow direction B in FIG. 11, cross-sectional direction DD) is transmitted to the gear shaft 624. This rotational movement of the gear shaft 624 is then transmitted via the first tooth 625 to the third planetary gear 622c of the right planetary stage in the illustration of FIG.

[0040] 9, the gear mechanism 6 can be seen in an enlarged cross-sectional view with a different cross-sectional orientation. The drive shaft 41 of the electric motor 4 runs through the gear mechanism 6 and drives it via a drive wheel 63. The rotational movement of the drive shaft 41 is then transmitted from the drive wheel 63 through a force limiting unit 61, a planetary gear 62 and finally a housing 60 to the belt shaft 5 with different functions that will be explained in more detail below.

[0041] The gear mechanism 6 can be seen in the cross-sectional direction AA in Fig. 10. The drive shaft 41 extends through the first planet carrier 621a, which can rotate freely relative to the drive shaft 41. Furthermore, the first planet carrier 621a is connected in a rotationally fixed manner to the housing 60 of the gear mechanism 6 via the latch contour 6212 and the spherical, spring-loaded blocking part 64 engaging therein, in the counterclockwise rotational direction A, which is the safety belt retraction direction, until a torque determined by the spring pretensioning of the blocking part 64 is reached. Due to the rotational connection of the planet gear 62 to the housing 60 created in this way, the planet gear 62 is simultaneously connected to the belt shaft 5. As a result of this rotational connection, when the electric motor 4 is activated, a driving rotational movement of the drive shaft 41 occurs via the drive wheel 63, the gear shaft 624, the planetary gear 62 and finally the housing 60 of the gear mechanism 6 in the winding direction of the safety belt wound on the belt shaft 5 in the direction of arrow A, so that the belt shaft 5 can be wound into a parking position and the safety belt can be retracted after it has been unwound. For this purpose, the driving rotational movement of the electric motor drive shaft 41 is transmitted via the drive wheel 63 to the gear shaft 624 via a first pawl 632 attached to the drive wheel 63 and engaging with a third tooth 626. In this case, the first pawl 632 and the third helical tooth 626 are oriented in such a way that a rotational movement is transmitted in this direction of rotation but not in the other direction of rotation.

[0042] In this function, the electric motor 4 acts as a retraction aid for the safety belt. The force-limiting unit 61, together with the planetary gear 62 and the housing 60, as an assembly, is driven by the drive wheel 63 with a transmission ratio of the rotational movement of the drive shaft 41 of 1:1. Due to the planetary gear 62 having a predetermined stiffness, the rotational movement of the gear shaft 624 is transmitted 1:1 to the housing 60 via the spring-loaded blocking part 64 during the retraction of the safety belt into the parking position without actuating the planetary gear 62. If the blocking part 64 is pretensioned with a sufficiently high spring force, the predetermined stiffness of the planetary gear 62 can also be omitted. In this case, the drive shaft 41, the drive wheel 63, the gear shaft 624, the housing 60, and finally the belt shaft 5 rotate at the same speed in the retraction direction of the safety belt.

[0043] Furthermore, the belt retractor allows for reversible belt tensioning with higher retraction forces on the safety belt in order to eliminate belt slack that may occur before or in the early stages of an accident in the driving rotation direction of the electric motor 4 in the cross-sectional view of Figure 11. For this purpose, the electric motor 4 first drives the belt shaft 5 with the same driving rotational movement via the drive wheel 63, along the same force transmission path as in its function as a retracting aid in the retracting direction of arrow B, but at a much higher rotational speed. In this case, belt slack is rapidly eliminated until the belt force to be overcome by the safety belt increases to an extent that it exceeds the self-locking of the planetary gear 62 and / or the spring pretensioning of the blocking part 64. This increase in belt force results in the housing 60 of the gear mechanism 6 no longer being able to rotate further, and the internal toothing 601 becomes a stationary tooth. During this phase, the planetary gear 62 temporarily becomes a rotation-reversing gear, and the first planetary carrier 621a is driven to rotate in the direction of safety belt extension by the first planetary gear 622a rolling on the stationary internal teeth 601. At the same time, in addition to a sudden increase in the rotational speed of the electric motor 4 to activate the reversible belt tensioning, the locking unit 8 is also activated, and the lever of the actuator 82 engages with the teeth of the control disc 80, thereby blocking the control disc 80 from rotating in the direction of safety belt extension. The second blocking claw 6211 attached to the first planetary carrier 621a engages with the pin of the bean-shaped control contour of the control disc 80 and is thereby connected to the control disc 80. As a result, the rotational movement of the first planet carrier 621a relative to the blocked control disc 80 forces the second blocking pawl 6211 to undergo a pivoting movement defined by the shape of the control beans in the control disc 80, during which the control disc 80 engages with the internal teeth 71 of the web 7, through which the first planet carrier 621a extends. This engagement of the second blocking pawl 6211 then blocks the first planet carrier 621a in the extension direction of the safety belt and terminates the rotational movement of the first planet carrier 621a with its direction of rotation reversed.

[0044] The blocked first planet carrier 621a then forms a thrust bearing fixed to the vehicle, and the housing 60 and / or the belt shaft 5 are now driven in the winding direction with higher torque by the electric motor 4 by operating the planet gear 62 at a rotational speed that is converted into a lower rotational speed. As a result, the safety belt is then pulled with an increased tension of, for example, 1000 N, and further belt slack is removed from the safety belt. In this case, the second pawl 633 of the drive wheel 63 moves with a pawl against the internal toothing 617, and the parking pawl 629 of the carrier part 612 moves with a pawl against the second tooth 627 of the gear shaft 624, so that the planet gear 62 is driven via the gear shaft 624 without the unlocking ring 611 or the carrier part 612 being retracted. Furthermore, due to the reduction of the planetary gear 62, the gear shaft 624 rotates faster than the belt shaft 5 and therefore faster than the housing 60, which is made possible by the fact that the gear shaft 624 can rotate freely relative to the unlocking ring 611 (center view of FIG. 11 ) and at the same time can be rotated by the pawl movement of the parking pawl 629 relative to the carrier part 612 (left view of FIG. 11 ). As the carrier part 612 is blocked relative to the housing 60 via the blocking element 613, the carrier part 612 rotates at the same rotational speed together with the housing 60 and at the same time can perform a rotational movement relative to the gear shaft 624 by the pawl movement of the parking pawl 629.

[0045] In a further function, the belt retractor, in cooperation with the electric motor 4, operates as a controlled force limiter, which allows a force-limited extension of the safety belt, followed by reversible tensioning, to reduce the load on the occupant during the forward displacement phase of the occupant in an accident. For this purpose, the belt retractor has a force-limiting unit 61, the operating principle of which will be explained in more detail below with reference to FIGS. 11 to 13. FIG. 11 shows the position of the interacting parts of the force-limiting unit 61 before activation of the controlled force limiter, i.e., for example, during reversible belt tensioning, winding into the parking position (winding assistance), or the belt reminder function, as described below. The unlocking ring 611 is arranged in a rotational angle position in which it radially supports the blocking elements 613 by means of the inclined portions 6161 of the control contour 616, in particular by means of the flat or circular ring cross-sectional shape portions at the ends of the inclined portions 6161, thereby forcing them into a radially extending blocking position.

[0046] Inside, the housing 60 has a structure consisting of two inclined portions 602 and 604 that rise in opposite circumferential directions and have different inclination angles, and a web 605 arranged between them, extending in the axial direction, and having a surface in the shape of a flat or circular ring cross section. The unlocking ring 611 is configured with the web 605 having a cutout 6111 that is slightly larger in the circumferential direction than the web 605 so that the unlocking ring 611 can perform a slight rotational movement relative to the housing 60 in relation to the rotation axis of the belt retractor or belt shaft 5. In this case, the web 605 is intentionally designed to be longer in the axial direction than the two inclined portions 602 and 604 so that the unlocking ring 611 has the web 605 in one plane and the blocking element 613, which is displaceably pressed against the laterally arranged carrier part 612, is arranged in a plane axially adjacent to the unlocking ring 611. Furthermore, the blocking element 613 is supported radially inwardly on an inclined portion 6161 of a control contour 616 on the axially protruding annular flange of the unlocking ring 611. As a result, the blocking element 613 is located circumferentially on the steeper inclined portion 604 of the housing 60, thereby connecting the carrier part 612 to the housing 60 in the clockwise direction and thus in the retraction direction of the safety belt in the example of Fig. 11. Thereby, the carrier part 612 is blocked in the clockwise direction relative to the housing 60 via the blocking element 613 abutting laterally against the steeper inclined portion 604.

[0047] Starting from this initial position, the locking unit 8 is activated before the start of controlled, force-limited belt elongation. The lever of the actuator 82 then engages the teeth of the control disc 80, blocking the control disc 80 in the direction of belt elongation. The electric motor 4 is then activated to drive the drive wheel 63 in the direction of belt elongation. As a result, the control disc 80 is also driven in the direction of belt elongation, and the second blocking pawl 6211 is forced to move against the internal teeth 71 of the web 7 fixed to the housing, blocking the first planet carrier 621a in the direction of safety belt elongation. Furthermore, the unlocking ring 611 is also driven in the direction of elongation via the radially outer second pawl 633 attached to the drive wheel 63. As a result, the unlocking ring 611 is rotated relative to the carrier part 612 to such an extent that the blocking elements 613 lose their radially inward support via the inclined portion 6161 of the control contour 616. At the same time, during this initial stage of the forward displacement or after reversible or irreversible belt tensioning, a considerable tension force of the safety belt is already acting on the safety belt, which in a first step rotates the belt shaft 5 together with the gear mechanism 6 in the extension direction by a very short rotation angle, so that the second blocking pawl 6211 on the first planetary carrier 621a is forced by the blocked control disk 80 to move further towards the tooth 71 and blocks the first planetary carrier 621a relative to the belt retractor frame 1, if the blocking has not yet been completely completed by the previous drive of the control disk 80 via the electric motor 4. In this case, the belt shaft 5 rotates without the unlocking ring 611 rotating relative to the gear mechanism housing 60 until the second blocking pawl 6211 is locked. After the first planetary carrier 621a is blocked, the tension force exerted by the safety belt results in a force transmission to the planetary gear 62.

[0048] Since the first planetary carrier 621a is blocked via the second blocking pawl 6211, the first stage of the planetary gear 62 becomes a rotation-direction-reversing gear and the belt shaft 5 together with the housing 60 of the gear mechanism 6 can only rotate further in the direction of safety belt extension, because under the action of the tensioning force the first planetary gears 622a no longer circulate but instead rotate about their rotation axis and only transmit the rotational movement to further planetary stages in the opposite direction of rotation. In the case of a preceding reversible belt tensioning movement envisaged in the event of an accident, the first planetary carrier 621a is already blocked by the preceding tensioning movement and the above-mentioned blocking process for activating the force-limited belt extension movement is omitted or the first planetary carrier 621a is already blocked at the start of activation of the electric motor 4 for controlled, force-limited belt extension. By blocking the first planet carrier 621a, the rotational speed of the belt shaft 5 and the housing 60 is converted into a faster rotational movement due to the transmission ratio and finally transmitted to the carrier part 612, to which the third planet gear 622c of the last planetary stage is attached and to which the blocking element 613 is displaceably driven. At the planet gear 62, a reaction torque caused by the belt tension therefore acts on the carrier part 612 in the direction of the arrow and on the blocking element 613 in the circumferential direction. Since the blocking element 613 is no longer supported radially inward by the control contour 616, it slides down the inclined part 604 of the housing 60, thereby performing a forced movement directed radially inward, during which it slides into the recess 6162 of the control contour 616. As a result, the blocking of the carrier part 612 relative to the housing 60 in the circumferential direction is released, and the carrier part 612 can rotate by a small angle, exactly 90 degrees, relative to the housing 60 by the four blocking elements 613, which in this case are arranged at 90 degrees to each other. At the same time, the housing 60 thus allows the belt shaft 5 to rotate by small rotation angles in the direction of extension, after which these rotation angles are again stopped since the blocking element 613 again rides up on the inclined portion 6161 of the control contour 616 and is supported radially inwards by said inclined portion 6161 and is thereby pushed outwards.Here, the blocking element 613 extends radially outward into the free space created by the much flatter ramp 602 behind the web 605 until it finally comes to rest again against the steeper ramp 604 of the housing 60 in the circumferential direction, blocking further rotational movement of the carrier part 612 relative to the housing 60.

[0049] The blocking element 613 forms the first blocking device here, which allows force-limited extension of the safety belt by its movement in a repetitive process consisting of releasing and blocking the extension movement of the safety belt. In this case, the electric motor 4, when activated, serves to trigger or enable the movement of the first blocking device by driving the unlocking ring 611 with the control contour 616 provided thereon, thereby causing or enabling the release of the blocking element 613 in relation to the tension acting on the safety belt. In this case, the shape of the radial control contour 616 with alternatingly arranged ramps 6161 and recesses 6162 is particularly important, as it forces, enables, and controls the radial movement of the blocking element 613, which is particularly important for releasing and blocking the first blocking device. Furthermore, the planetary gear 62 is particularly important here, as the extension rotational movement of the belt shaft 5 is converted by the planetary gear 62 into a substantially faster rotational movement of the carrier part 612, thereby increasing the blocking path available for blocking the first blocking device. Furthermore, the forces acting on the blocking element 613 are also reduced as a result. Furthermore, it is advantageous that the gear mechanism 6 in the form of the planetary gear 62 operates at this stage as a rotation-reversing gear, since the carrier part 612 and the housing 60, with the planetary gear 62 disposed therebetween, undergo opposite rotational movements, further increasing the relative movement required to block the first blocking device. Here, the housing 60 with its internal teeth 601 forms a first part of the rotation-reversing gear, which is rotationally connected to the belt shaft 5. Here, the carrier part 612 forms a second part of the rotation-reversing gear according to the invention, which second part is driven by the rotation-reversing gear into a rotational movement directed in the opposite direction relative to the housing 60, i.e., relative to the first part, and thus the blocking element 613, i.e., the first blocking device, is disposed between the first and second parts.

[0050] The housing 60 of the gear mechanism 6, in this case the first part, has a blocking contour formed by a steeper ramp 604 which, when a blocking element 613 abuts, blocks or stops further rotation of the carrier part 612 relative to the housing 60.

[0051] Said first part is formed by a housing 60 in the form of a tubular axial extension, which is connected in a rotationally fixed manner to the belt shaft 5 and at the same time forms, in a second function, a housing 60 for the gear mechanism 6. The housing 60 encases the gear mechanism 6 towards the outside, thereby protecting it from external influences. Furthermore, in a compact design, the housing 60 forms, on its radially inner side, a blocking structure for a blocking element 613.

[0052] The force limiting feature can be further influenced by driving the unlocking ring 611 at an increased rotational speed, so that the unlocking ring 611 with the control contour 616 follows the gear mechanism housing 60 rotating in the extension direction, thereby reducing the number of blocking elements 613 blocking the rotation of the gear mechanism housing 60. In an extreme case, it is even possible to drive the unlocking ring 611 in the extension direction at a rotational speed corresponding to the rotational speed of the gear mechanism housing 60 and hold the unlocking ring 611 during processing in a rotational angle position relative to the gear mechanism housing 60, in which the inclined portion 6161 of the control contour 616 is oriented during rotation at a rotational angle between the two inclined portions 602 and 604 of the different webs 605 of the gear mechanism housing 60, so that when moving on the inclined portion 6161 of the control contour 616, the blocking element 613 does not block when resting on the inclined portion 604 and can circulate virtually without blocking. This holds the unlocking ring 611 in an "open position" relative to the gear mechanism housing 60, preventing blocking of the carrier part 612 relative to the gear mechanism housing 60. In this way, the fastest possible belt extension can be achieved with the lowest possible force limit, which is provided solely by friction-related energy breakdown in the gear mechanism 60.

[0053] The spring 615 is designed so that its spring force is significantly greater than that of the main spring 91. As a result, the electric motor 4 directly drives the belt shaft 5 in the winding or unwinding direction via the unlocking ring 611, the spring 615 and the housing 60, thereby increasing or decreasing the retraction force acting on the belt shaft 5, thereby achieving an additional comfort function. In this case, the planetary gear 62 is bridged by the force transmission via the spring 615. This applies to the transmission of very small torques and corresponding rotational speeds, and the gear shaft 624 is not driven, since the inner first pawl 632 does not engage with the third tooth 626 of the gear shaft 624. If the housing 60 is additionally connected circumferentially to the first planetary carrier 621a via the spring-loaded blocking part 64, this, in addition to the possible stiffness of the planetary gear 62, results in blocking of the planetary gear 62 and the transmission of the rotational movement of the electric motor 4 to the belt shaft 5 in a 1:1 ratio.

[0054] In a further function, the electric motor 4 is used to generate a clearly perceptible vibration (belt reminder, or "tactile warning") on the belt, which is clearly noticeable to the occupant. Figure 14 shows three cross-sectional views of the belt retractor during the belt reminder function. During the belt reminder function, the electric motor 4 drives the drive wheel 63 in the extension direction in the same manner as in controlled, force-limited belt extension, except that no tension is applied to the safety belt at this time. As a result, the unlocking ring 611 is retracted in the extension direction via the pawl 633 of the drive wheel 63. This rotational movement of the unlocking ring 611 is transmitted to the belt shaft 5 via the spring 615, and the carrier part 612 and the entire gear mechanism 6 are retracted as an assembly by the blocking element 613 due to the lack of tension in the safety belt. The electric motor 4 rotates enough to unwind approximately 5-10 mm of belt length before the electric motor 4 is de-energized. In this case, the electric motor 4 is energized in a pulsed manner, i.e., the power supply is interrupted at regular intervals. When the power supply to the electric motor 4 is interrupted, the belt shaft 5 is no longer subjected to a force in the belt extension direction, and the spring force of the main spring 91 in the spring cassette 9 pulls the belt shaft 5 back in the belt retraction direction again, and the process is then repeated. This induces vibration in the safety belt around the occupant without increasing the belt force applied by the safety belt. In this case, the occupant receives the belt reminder only as a "wobble" of the belt. The length of belt extension or the frequency of the "wobble" can be set by the duration of the power supply and the duration of the interruption of the current supply. In either case, the presence of the main spring 91 allows the electric motor 4 to be used for further functions without additional cost.

[0055] Simultaneously with the activation of the electric motor 4, the actuator 82 can be energized so as to engage the tooth of the control disk 80 with its lever. As a result, the second blocking pawl 6211 is extended and directed towards the tooth 71 of the web 7 during the activation of the electric motor 4 and the driving of the belt shaft 5 in the extension direction. As a result, the unwinding movement of the safety belt during activation of the belt reminder function is limited to the length of the locking path, and the safety belt cannot be released indefinitely under any circumstances. This blocking can then be released again when the main spring 91 drives the belt shaft 5 again in the retraction direction.

[0056] 15 and 16 show a drive wheel 63 with an unlocking ring 611 according to a second embodiment. The drive wheel 63 has two axially protruding annular projections 636 and 637, which are concentric with an axial opening with internal teeth 631 and are interrupted in each case in segments to form openings 638 and 639. Furthermore, a first claw 632 and a second claw 633 are provided, which support each other and are pretensioned via a single annular spring 65. The annular spring 65 is circumferentially fixed to the drive wheel 63 at its outer first end 651 and is mounted at its inner second end 652 in a pocket of the inner first claw 632. 15, the annular spring 65 is designed to load the two abutting first and second claws 632, 633 in a relaxed state, such that the outer second claw 633 projects radially outward through the opening 638 of the radially outer annular protrusion 636 and engages with the internal tooth 617 of the considered unlocking ring 611, while the inner first claw 632 with its block tip is in front of the opening 639 of the inner annular protrusion 637 and does not engage with the third tooth 626 of the considered gear shaft 624. However, even if the inner first claw 632 engages with the third tooth 626, this does not disadvantage its function, since the engagement is irrelevant for this function.

[0057] 17 shows a belt retractor with a drive wheel 63 according to the second exemplary embodiment according to FIGS. 15 and 16 in the cross-sectional direction DD of FIGS. 5 and 9. The outer second pawl 633 is pushed to a radially outer position by the annular spring 65 of the drive wheel 63, and in this position engages with the teeth in the internal teeth 617 of the unlocking ring 611, thereby creating a rotationally fixed connection between the drive wheel 63 and the unlocking ring 611, except for a small amount of play, until a predetermined torque and a predetermined rotational speed of the electric motor 4 are exceeded. Since the spring 615 acting between the unlocking ring 611 and the housing 60 has a significantly higher spring force than the main spring 91, the belt shaft 5 can be driven in both the retracting and unreeling directions via the second pawl 633, the unlocking ring 611, and ultimately the spring 615, thereby reducing or increasing the retraction force acting on the belt shaft 5. (Comfort feature) Furthermore, after undoing the belt, the safety belt can be retracted into a parking position (belt parking) with increased retraction force. In principle, torque can be transmitted only via the spring 615. However, if necessary, the transmittable torque can alternatively or additionally be increased by abutment, adapted to the lateral shape of the radial webs of the unlocking ring 611, which border the cutout 6111, on the web 605 of the housing 60. The rotational connection created in this way makes it possible to dispense with the rotational connection created via the block part 64 (see FIG. 10) of the first exemplary embodiment.

[0058] 18 and 19 show the belt retractor with the drive wheel 63 according to the second exemplary embodiment in the initial and later stages of reversible belt tensioning. Starting from the position of the two pawls 632 and 633 shown in FIG. 17 before the electric motor 4 is activated, when the electric motor 4 is activated for reversible belt tensioning, inertia causes the pawls 632 and 633 to pivot radially inward against the spring force of the annular spring 65 due to the high torque and much higher rotational speed. In this case, the radially outer second pawl 633 disengages from the internal tooth 617 of the unlocking ring 611, and the radially inner first pawl 632 engages with the third tooth 626 of the gear shaft 624. The inner first pawl 632 engages with the third tooth 626 of the gear shaft 624, while the second pawl 633 is simultaneously disengaged, thereby creating a rotational connection between the drive wheel 63 and the gear shaft 624, while releasing the rotational connection between the drive wheel 63 and the unlocking ring 611. The electric motor 4 then drives the gear shaft 624 in the retracting direction via the drive wheel 63, as can be seen in Fig. 19, and the belt shaft 5 is driven in the retracting direction at a reduced rotational speed but with a higher torque, according to the same principle as the movement sequence of the planetary gear 62 described in relation to the first exemplary embodiment according to Fig. 11.

[0059] 20 and 21 it can be seen that the belt retractor functions as an electronic force limiter with a drive wheel 63 according to the second exemplary embodiment, the movement sequence and force-limited belt extension being carried out according to the same movement sequence as already described for Figures 12 and 13. In this respect, reference is made to the description therein.

[0060] Here too, the electric motor 4 drives the unlocking ring 611 in the direction of extension of the safety belt via the radially outer second claw 633, so that the blocking element 613 loses support on the control contour 616 and is thereby pushed radially inward from its blocking position, allowing force-limited belt extension movement.

[0061] In FIG. 22, it can be seen that the belt retractor functions as a belt reminder, the movement sequence being identical to that described for FIG. 14, and the drive wheel 63 being provided according to FIG.

[0062] The belt retractor may be provided with the described force limiting unit 61 as a single function. However, it is also conceivable that the belt retractor may be provided with some or all of the described additional functions, such as a reversible belt tensioner, a retraction aid, a comfort function for reducing or increasing the retraction force, or a belt reminder, which may be realized as described when using a single electric motor 4. [Explanation of symbols]

[0063] 1 frame 2 slots 3 Housing shell 4 electric motors 41 Drive shaft 42 Toothed end 5 Belt shaft 50 Belt shaft body 51 Torsion bar 52 Radial flange 521 Finger 6 Gear mechanism 60 Gear mechanism housing 601 Inner teeth 602 Slope 603 Recess 604 Slope 605 Web 61 Force Limiting Unit 611 Unlock Ring 6111 Notch 6112 Opening 612 Carrier part 613 Block Elements 614 recess 615 Spring 6151 Second end 6152 First end 616 Control Contour 6161 Slope 6162 recess 617 Inner teeth 618 pins 62 Planetary Gear 621a 1st planet carrier 6211 Block Nail 6212 Latch Profile 621b Second Planet Carrier 622a 1st planetary gear 622b Second planetary gear 622c 3rd planetary gear 623 Ring Gear 624 Gear shaft 625 First Tooth 626 Third Tooth 627 Second Tooth 628 Ring Section 629 Parking Claw 63 Drive Wheel 631 Inner teeth 632 First Claw 633 Second Claw 634 Spring Plate 635 Annular flange 636 First annular protrusion 637 Second annular protrusion 638 Opening 639 Opening 64 Block Part 65 Annular spring 651 First End 652 Second End 7. Web 71 Inner teeth 8 Lock Unit 80 control disk 81 AC Block Claw 82 Actuator 9 Spring cassette 90 Housing 91 Main spring 92 Housing cover

Claims

1. a belt shaft (5) rotatably attached to the frame (1) and around which a safety belt can be wound; a force limiting unit (61) that, when activated, allows a rotational movement of the belt shaft (5) in the extension direction of the safety belt; A belt retractor comprising: the force limiting unit (61) comprises an electric motor (4) and a first blocking device; the first blocking device is configured to release and reblock in a repeated sequence the rotational movement of the belt shaft (5) in the extension direction in a manner controlled by the operation of the electric motor (4); A belt retractor characterized by:

2. the first blocking device is movable from a position blocking the belt shaft to a position releasing the belt shaft in response to operation of the electric motor; the first blocking device automatically blocks again after a predetermined angle of rotation of the belt shaft (5) as a result of the rotational movement of the belt shaft (5) in the extension direction being enabled, 2. The belt retractor according to claim 1, wherein:

3. an unlocking ring (611) driven by said electric motor (4) and having a control contour (616); the first blocking device is formed by at least one blocking element (613) abutting against the control contour (616), 3. The belt retractor according to claim 2, wherein:

4. the control contour (616) is formed by a ramp structure having a number of ramps (6161) corresponding to the number of the blocking elements (613), and recesses (6162) arranged between the ramps (6161) and against which the blocking elements (613) alternate in the blocking position and the release position; 4. The belt retractor according to claim 3, wherein:

5. a rotation direction reversing gear rotatably connected to the belt shaft (5) via a first portion; the first blocking device is disposed between the first part of the rotation direction reversing gear and the second part of the rotation direction reversing gear, the second part being driven by the rotation direction reversing gear in a rotation direction opposite to that of the belt shaft (5); The belt retractor according to any one of claims 1 to 4, characterized in that:

6. The second part converts the rotational movement converted by the rotation direction reversing gear to a higher rotational speed relative to the first part.

6. The belt retractor according to claim 5, wherein:

7. the rotation direction reversing gear is formed by a planetary gear (62); the reversal of the rotation direction in the rotation direction reversal gear is realized by a first planet carrier (621) of the planet gear (62), which is blocked by a second blocking device relative to the frame (1) of the belt retractor; 7. A belt retractor according to claim 5 or 6.

8. the first part or the second part of the rotation direction reversing gear has a blocking profile, and the first blocking device is stationary in the blocking position; The belt retractor according to any one of claims 5 to 7, characterized in that

9. the first part is formed by a tubular axial extension, which is rotationally fixedly connected to the belt shaft (5) and forms the housing (60) of the rotation direction reversing gear; The belt retractor according to any one of claims 5 to 8, characterized in that

10. the blocking profile is formed by a circumferentially oriented ramp (604) located inside an annular extension and against which the blocking element (613) abuts at the blocking position; 10. A belt retractor according to claim 8 or 9, when referring back to claim 8.

11. The unlocking ring (611) is spring-loaded against the belt shaft (5) by a spring (615). A belt retractor according to any one of claims 3 or 4, or according to any one of claims 5 to 10 when referring back to any one of claims 3 or 4, characterized in that

12. The belt shaft (5) is spring-loaded in the direction of winding up the safety belt by a main spring (91) fixedly supported on the frame, The spring force of the main spring (91) is smaller than the spring force of the spring (615) that applies load to the unlocking ring (611).

12. The belt retractor according to claim 11, wherein:

Images