Belt retractor

The invention relates to a belt rectractor (10) for a seatbelt of a motor vehicle. The belt retractor (10) comprises a belt spool (14) which is rotationally connected to a belt spool-side end of a torsioning rod, said torsioning rod being operatively connected to a locking mechanism (20) at a locking mechanism-side end. In a locked state, the locking mechanism-side end of the torsioning rod is rotationally fixed to a frame (12). The belt spool-side end can then be rotated relative to the locking mechanism-side end in an unwinding direction (16) under the effect of torsion from the torsioning rod. The belt spool (14) is additionally rotationally fixed to the frame (12) in the unwinding direction (16) in a stopped state of a stopping mechanism (22). The stopped state is set of the belt spool-side end is rotated by a specified number of rotations relative to the locking mechanism-side end in the locked state of the locking mechanism (20). The stopping mechanism (22) comprises a locking pawl which is mounted on the belt spool (14).

RELATED APPLICATIONS

This application corresponds to PCT/EP2017/078832, filed Nov. 10, 2017, which claims the benefit of German Application No. 10 2016 121 609.7, filed Nov. 11, 2016, the subject matter of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The invention relates to a belt retractor for a seat belt of a motor vehicle, having a belt reel which is mounted in a frame so as to be rotatable in an unwinding direction and a winding direction, which is in the opposite direction to the unwinding direction, and is non-rotatably connected to a belt-reel-side end of a torsion rod, which is arranged substantially coaxially to the belt reel, wherein the torsion rod is operatively connected by way of a locking-mechanism-side end, which is opposite the belt-reel-side end, to a locking mechanism and, with the locking mechanism in a locked state which is set up in a vehicle-sensitive and/or webbing-sensitive manner, the locking-mechanism-side end of the torsion rod is fixed to the frame so as to be non-rotatable in the unwinding direction, wherein in the locked state, with the torsion rod under torsion, the belt-reel-side end is rotatable in the unwinding direction relative to the locking-mechanism-side end, wherein the belt reel, with a stopping mechanism in a stopped state, is fixed to the frame so as to be non-rotatable in the unwinding direction, and wherein the stopped state is set up when the belt-reel-side end is twisted by a predefined number of revolutions in relation to the locking-mechanism-side end, with the locking mechanism in the locked state.

Such belt retractors are known from the prior art. The torsion rod, in this case, acts as a component part of a belt force limiting mechanism. By means of which belt force limiting mechanism, the force exerted by a seat belt onto a passenger is able to be delimited by the unwinding of a certain length of the webbing of the seat belt being allowed.

Known stopping mechanisms include, for example, a nut which is mounted on the torsion rod via a thread so as to be rotatable and at the same time is connected non-rotatably to the belt reel. If the torsion rod is then twisted, it is rotated relative to the belt reel and relative to the nut. After a predefined number of revolutions, the nut runs up to a locking disk by way of an end face. Further rotation of the nut on the torsion rod is thus blocked. Consequently, further twisting of the torsion rod is also blocked and the belt reel is unable to rotate further in the unwinding direction relative to the frame. The belt reel and the torsion rod now behave as a one-piece axle. Consequently, the webbing of the seat belt is ultimately unable to be unwound any further from the belt reel. The belt force delimitation is at an end.

Such stopping mechanisms are also designated in part in the prior art as counting mechanisms. However, strictly speaking a counting s mechanism only designates the mechanism which determines when the stopped state of the stopping mechanism should be set. A counting mechanism cooperates very closely with a stopping mechanism but is, in principle, different to it. Said strict understanding of counting mechanisms and stopping mechanisms underlies the statements below.

SUMMARY OF THE INVENTION

The object of the invention is the further improvement of belt retractors which include a locking mechanism, a belt force delimiting mechanism and a stopping mechanism. A belt retractor which has compact dimensions is to be created in particular in this case. In addition, such a belt retractor, with the stopping mechanism in the stopped state, should be able to be loaded as evenly as possible and should consequently function reliably and be light in weight.

The object is achieved by a belt retractor of the type named in the introduction where the stopping mechanism includes a pawl which is mounted on the belt reel. In a stopped state, the belt reel is fixed non-rotatably on the frame by means of the pawl. In a released state, the belt reel is rotatable in relation to the frame. The pawl is then disengaged. Such a pawl is able to assume various switching states in a defined manner so that the stopped state and the released state of the stopping mechanism are able to be set in a precise and reliable manner. In addition, a pawl is a relatively small and light component so that the belt retractor is also able to be designed in a small and light manner. In particular, such a belt retractor is able to be realized along a center axis of the belt reel with a short length.

The belt tensioner can also additionally include a gas-powered belt tensioner, by way of which so-called belt pretensioning is able to be carried out.

The belt reel is preferably fixed on a side of the frame opposite the locking mechanism in the stopped state. From the perspective of the torsion rod, the belt reel is therefore fixed by the stopping mechanism at the belt-reel-side end thereof. The locking mechanism cooperates in a known manner with the locking-mechanism-side end of the torsion rod. The belt reel, more precisely the torsion rod connected to the belt reel, is therefore retained at both its ends. The belt retractor and its components are loaded evenly in the stopped state in this manner. Consequently, the belt retractor can be constructed simply and lightly compared to known belt retractors. In particular, it is possible to dispense at least in part with one-sided reinforcement of the belt retractor.

According to an embodiment, in the stopped state the pawl engages in a toothing of an actuating disk of a clutch and the clutch couples the belt reel with the frame so as to be non-rotatable in the unwinding direction, in particular the pawl is spring-loaded in the direction of the toothing. A clutch is described in detail, for example, in U.S. patent application Ser. No. 15/228,056. Such a clutch is designed very compactly in the direction of a rotational axis of the belt reel so that an associated belt retractor only takes up a small amount of installation space. Furthermore, the clutch is able to absorb large forces and is not restricted as to the number of clutch operations, i.e. the clutch is able to be engaged and disengaged an arbitrary number of times. The pawl is always in a defined state as a result of the spring loading. In case of doubt, it connects the clutch so that the belt reel is coupled with the frame. A high level of passenger safety is therefore ensured. Furthermore, the effect of the spring loading of the pawl is that the stopping mechanism and the clutch are able to be controlled quickly and precisely. Unwanted noises, e.g. as a result of rattling, are also avoided.

The clutch can be actuated by one single actuating disk or by multiple actuating disks that are coupled together, that is to say can be transferred into a state in which it connects the belt reel to the frame in a non-rotatable manner.

In one variant, the aforenamed actuating disk is a first actuating disk and, in the stopped state, the first actuating disk is rotated by a predefined first rotational angle in relation to a second actuating disk of the clutch, wherein, in the stopped state, the first actuating disk and the second actuating disk are rotationally coupled in an actuating direction of the clutch. To actuate the clutch, the pawl therefore first of all engages in the toothing of the first actuating disk. The first actuating disk is consequently non-rotatably connected to the belt reel. Said bond produced from belt reel and first actuating disk can then be rotated again by a predefined first rotational angle in relation to the second actuating disk. In this case, the torsion rod is rotated about said angle. The first actuating disk and the second actuating disk are only then rotationally coupled together in an actuating direction of the clutch and the clutch is transferred into its closed state, in which it fixes the belt reel to the frame. The first actuating disk and the second actuating disk can be coupled together, for example, by means of a circumferential groove which extends around in part and an entrainment lug which is arranged therein. The entrainment lug then extends by the predefined first rotational angle in the circumferential groove before it creates the connection, non-rotatable on one side, between the two actuating disks via the groove end. A secondary counting mechanism is consequently integrated in the actuating mechanism of the clutch. The revolutions or rotational angles recorded by the secondary counting mechanism are added to the revolutions or rotational angles recorded by the counting mechanism. A comparatively smaller and compactly designed counting mechanism is therefore able to be used, as a result of which the design of the belt retractor is particularly light and compact.

In the aforenamed variant, with the stopping mechanism in a released state, the first actuating disk and the second actuating disk are rotatable by the predefined first rotational angle relative to one another in the actuating direction of the clutch. This is achieved by means of the above-mentioned entrainment lug which is freely movable inside the circumferential groove. The entrainment lug is preferably arranged at a first end of the circumferential groove in the released state and at an end which is opposite this in the stopped state. The torsional angle of the torsion rod, provided within the framework of the actuation of the clutch, can thus be adjusted with a high degree of precision.

The actuating mechanism of the clutch can also include a total of three actuating disks.

Such an embodiment provides that a third actuating disk of the clutch is interposed between the first actuating disk and the second actuating disk, wherein in the stopped state the third actuating disk is rotated by a predefined second rotational angle in relation to the first actuating disk and in the stopped state the third actuating disk is rotationally coupled with the first actuating disk in an actuating direction of the clutch, and wherein in the stopped state the second actuating disk is rotated by a predefined third rotational angle in relation to the third actuating disk and in the stopped state the second actuating disk is rotationally coupled with the third actuating disk in an actuating direction of the clutch. The coupling of the first actuating disk with the third and the coupling of the third actuating disk with the second is effected analogously to the above-described embodiment, for example by means of circumferential grooves and entrainment lugs. The additional torsional angle of the torsion rod, made possible and recorded by the actuating mechanism of the clutch, can consequently be enlarged further as a result of the additional actuating disk. Consequently, a particularly small and compact counting mechanism is also sufficient to record multiple revolutions or comparatively large torsional angles of the torsion rod.

In a preferred manner, the third actuating disk and the first actuating disk, with the stopping mechanism in a released state, are rotatable by the predefined second rotational angle in relation to one another in the actuating direction of the clutch and the third actuating disk and the second actuating disk, with the stopping mechanism in a released state, are rotatable by the predefined third rotational angle in relation to one another in the actuating direction of the clutch. Analogously to the previously named embodiment, the entrainment lugs, in this case, are arranged in the released state once again in a preferred manner at the assigned first ends of the corresponding circumferential grooves which are opposite the ends of the circumferential grooves at which the entrainment lugs are situated in the stopped state.

With the stopping mechanism in a released state, the pawl is retained in such a manner by a locking pin that it does not engage in the toothing. The locking pin interacts preferably in a positive locking manner with the pawl so that the pawl is retained reliably, i.e. even in the event of strong acceleration, deceleration or vibrations. In addition, a power supply is not necessary for retaining the pawl. The belt retractor is therefore always situated in a defined state. Furthermore, the locking pin does not take up much installation space.

The locking pin is advantageously mounted so as to be displaceable in the belt reel. The locking pin can therefore be displaced from a position in which it retains the pawl, into a position in which it releases the pawl. The same applies in reverse. The locking pin is consequently guided in a defined manner in the belt retractor, as a result of which the function thereof and the function of the belt retractor are ensured overall in a reliable manner.

In this case, in the released state the locking pin can be arranged in a retaining opening of the pawl and in the stopped state it can be arranged outside the retaining opening. The locking pin therefore cooperates with a defined location of the pawl. The locking pin is held securely in the retaining opening even where forces and vibrations act on the belt retractor. The position of the pawl is able to be controlled precisely as a result. Precise control of the stopping mechanism is ensured in this way, as a result of which a high level of safety is ensured for the passenger.

In a design alternative, the belt retractor includes a counting mechanism which is set up for the purpose of removing the locking pin from the retaining opening when the belt-reel-side end is twisted by the predefined number of revolutions in relation to the locking-mechanism-side end. Consequently, the torsion of the torsion rod and consequently the functionality of the belt force limiting means is precisely defined. The belt force limitation comes to an end after a fixed number of revolutions, that is to say before there is a risk of the torsion rod failing or too long a length of webbing of the seat belt unwinding from the belt reel. The number of revolutions about which the torsion rod is twisted before the locking pin is removed from the retaining opening and the stopped state is thus set, can be chosen, in principle, in an arbitrary manner. It can include a fraction of a full revolution but also more than one revolution. As an alternative to the number of revolutions, a rotational angle which can also be greater than 360° can be specified. A reliable belt force limitation is thus ensured by means of which a high level of safety for the passenger of a motor vehicle is provided, that is to say the user of the belt retractor.

In one embodiment, the counting mechanism can include a thread and a winding disk which is arranged substantially coaxially to the torsion rod, wherein the thread is connected to the locking pin at one end and to the winding disk at another end. The thread, in this case, can also be a cable, a cord, a wire or similar. A simple and reliable mechanism is thus provided, by means of which the locking pin is able to release the pawl. Furthermore, the thread and the winding disk are very light and they only require a small amount of installation space.

The winding disk, in this case, is coupled in a preferred manner non-rotatably with the locking-mechanism-side end of the torsion rod, in particular the winding disk is arranged on a locking disk of the locking mechanism. The winding disk is therefore rotated with the locking-mechanism-side end of the torsion rod and in particular with the locking disk. Once the locking pin does not rotate in relation to the belt-reel-side end of the torsion rod, a rotation of the winding disk relative to the locking pin takes place with the torsion rod being twisted, as a result of which the thread is wound onto the winding disk. Said mechanism is simple and very reliable. In a preferred manner, the winding disk is produced integrally with the locking disk. A saving in production efforts and costs is made as a result.

The thread can include a thread reserve which is arranged, in the released state, between the locking pin and the winding disk. In a preferred manner, in this case, the size of the thread reserve is such that the thread is not tensioned in the released state. The locking pin consequently holds the pawl securely without any force being exerted by the thread on the locking pin. The released state is therefore retained in a reliable manner and is not influenced by the counting mechanism even in the case of vibrations or similar.

In a preferred manner, the thread reserve is wound on the winding disk in the stopped state and the size of a free length of the free thread is such that the locking pin is removed from the retaining opening. The winding of the thread onto the winding disk take place during the twisting of the torsion rod and occurs without any notable resistance and is practically noiseless. As soon as a sufficient length of thread is wound on the winding disk, the locking pin is pulled out of the retaining opening. The stopped state is therefore reliably set. Possible sagging of the torsion rod during the torsion thereof is insignificant to the method of operation of the counting mechanism in this case so that a high level of functional reliability of the belt retractor is provided.

In addition, a length of the thread reserve can be matched to the predefined number of revolutions. The length of the thread between the winding disk and the locking pin is therefore chosen to be precisely of such a length that after the predefined number of revolutions the thread is tensioned between the winding disk and the locking pin and the locking pin is removed from the retaining opening. The predefined number of revolutions is able to be precisely adjusted and/or varied in a simple and cost-efficient manner by means of the length of the thread.

In one variant the thread is arranged in a housing which is connected non-rotatably to the belt reel. The thread is consequently protected against environmental influences and against catching on other elements of the belt retractor. In the stopped state the locking pin is also preferably situated at least in part in the housing. The belt retractor has a high level of reliability and a long service life in this way.

In an alternative embodiment the counting mechanism includes a latching continuation which is arranged on the locking pin, a latching element and an actuating disk which is arranged substantially coaxially to the torsion rod, wherein the latching element is arranged so as to be functional between the latching continuation and the actuating disk. The locking pin is therefore held by the latching element at its latching continuation and is controlled by the actuating disk. The latching continuation, the latching element and the actuating disk are produced, for example, from plastics material. Such a mechanism is simple in design and reliable in operation. Furthermore, a light overall weight of the belt retractor can be ensured in this manner.

In this case, the actuating disk can be coupled non-rotatably with the locking-mechanism-side end of the torsion rod, in particular the actuating disk is arranged on a locking disk of the locking mechanism. The actuating disk is therefore rotated with the locking-mechanism-side end of the torsion rod and in particular with the locking disk. Once the locking pin, the latching continuation and the latching element do not rotate in relation to the belt-reel-side end of the torsion rod, a rotation of the actuating disk relative to the aforenamed elements occurs when the torsion rod is twisted. Consequently, the latching element and the locking pin are positively controlled by means of the actuating disk in dependence on a rotational position of the locking-mechanism-side end of the torsion rod relative to its belt-reel-side end. Said mechanism is simple and very reliable. In a preferred manner, the actuating disk is produced integrally with the locking disk. A saving in production efforts and costs is made as a result.

According to a design alternative, the latching element engages by way of a latching-continuation-side end in a latching toothing which is arranged on the latching continuation, in particular the latching-continuation-side end is realized as a resilient latching arm. The latching continuation, and consequently the locking pin, are therefore retained by the latching element by means of the latching toothing. This prevents unwanted movement of the locking pin. The resilient latching arm is pre-stressed in particular in the direction of the latching toothing, as a result of which it retains the latching continuation securely. As a result, the latching continuation, and consequently the locking pin, is retained securely in its position, irrespective of possible environmental influences, e.g. vibrations. The counting mechanism and the stopping mechanism consequently operate in a reliable manner.

The latching toothing can be designed in such a manner that the latching element is displaceable in a direction of extraction of the locking pin relative to the latching continuation only under entrainment of the latching continuation and in a direction opposite to the direction of extraction by traveling over part of the latching toothing. Under entrainment of the latching continuation means, in this case, that no relative movement takes place between the latching continuation and the latching element. By means of the latching continuation, the locking pin can consequently either be retained in its position by the latching element or displaced in a defined manner in the direction of extraction. With sufficient displacement, the locking pin is removed from the retaining opening and the stopping mechanism is transferred into the stopped state. Displacement of the locking pin in the direction opposite to the direction of extraction by the latching element is not possible. The displacement of the latching element is controlled by the actuating disk. The locking pin is therefore controlled in a positive and reliable manner.

In an advantageous manner, in the stopped state, the latching continuation is displaced so far in the direction of the direction of extraction that the locking pin is removed from the retaining opening. The locking pin then releases the pawl in a controlled manner so that the stopped state of the stopping mechanism is set. A high level of safety for the passenger is consequently ensured.

In a design variant, in the released state the latching continuation is not displaced or is not displaced to a maximum extent in the direction of the direction of extraction that the locking pin is arranged in the retaining opening. The locking pin therefore continues to secure the pawl and the stopping mechanism is in the released state. The locking pin, in this case, is retained by the latching element and the actuating disk by means of its latching continuation. The released state is therefore set in a stable manner.

The latching element can abut against an actuating contour of the actuating disk by way of an actuating-disk-side end, in particular the latching element can be spring-loaded in the direction of the actuating disk. The actuating contour controls the movement of the latching element, i.e. it displaces the latching element in a controlled manner in the opposite direction to the direction of extraction of the locking pin and in a controlled manner allows the latching element to spring back in the direction of extraction of the locking pin. The latching element, in this case, interacts with the latching continuation in the above-described manner. The counting mechanism is therefore controlled overall by the actuating disk. Precise control is ensured as a result of the spring loading.

In a preferred manner, the actuating contour is realized in such a manner that the latching element is displaceable relative to the latching continuation by means of the actuating contour. As a result, the interaction between the latching element and the latching continuation described further above is controlled in dependence on the rotational position of the actuating contour. This is simple and reliable.

In addition, the actuating contour can be matched to the predefined number of revolutions. The actuating contour is formed then in such a manner that, after the predefined number of revolutions, the latching continuation, and consequently the locking pin, is removed from the retaining opening and the stopping mechanism is in the stopped state. The stopping mechanism can thus be controlled in a simple and reliable manner in dependence on the predefined number of revolutions. The belt force limitation comes to an end reliably as a result.

In a design alternative, the latching continuation and the latching element are arranged in a housing which is immovable relative to the belt reel, in particular the latching continuation and the latching element extend substantially parallel. The latching continuation and the latching element are consequently protected against environmental influences. In the stopped state, the locking pin is also preferably situated at least in part in the housing. The belt retractor has a high level of reliability and a long service life in this way. As a result of the parallel arrangement of latching continuation and latching element, only a small installation space is additionally taken up.

In an alternative embodiment, the counting mechanism includes a locking pin continuation which is arranged on an end of the locking pin remote from the pawl, a contact surface and a cutting disk, wherein the locking pin continuation abuts against the contact surface. The locking pin is therefore retained in its position by the contact surface. Movement of the locking pin is controlled by the cutting disk. The locking pin continuation and the contact surface are produced in a preferred manner from plastics material, the cutting disk is produced at least in part from metal. Such a mechanism is simple in design and reliable in operation. Furthermore, a low overall weight and a small installation space requirement can be ensured in this way.

The contact surface and the cutting disk can be coupled non-rotatably with the locking-mechanism-side end of the torsion rod, in particular the contact surface and the cutting disk are arranged on a locking disk of the locking mechanism. The contact surface and the cutting disk therefore rotate with the locking-mechanism-side end of the torsion rod and in particular with the locking disk. Once the locking pin and the locking pin continuation do not rotate in relation to the belt-reel-side end of the torsion rod, the cutting disk rotates relative to the aforementioned elements when the torsion rod is twisted. Consequently, by means of the cutting disk, the locking pin continuation, and consequently the locking pin, is controlled positively in dependence on a rotational position of the locking-mechanism-side end of the torsion rod relative to its belt-reel-side end. Said mechanism is simple and reliable. In a preferred manner, the cutting disk is produced integrally with the locking disk. A saving in production efforts and costs is made as a result.

In one embodiment, the cutting disk is at a spacing from the contact surface in a direction of extension of the locking pin continuation. The cutting disk, in this case, is positioned closer to the locking pin than the contact surface. The locking pin continuation can therefore be subdivided into two portions. A first portion extends between the locking pin and the cutting disk and a second portion extends between the cutting disk and the contact surface. Consequently, it is always ensured that the cutting disk is able to interact with the locking pin continuation and is thus always able to control the locking pin continuation.

The locking pin continuation can be spring-loaded in the direction of the contact surface. As a result, the locking pin continuation always abuts against the contact surface. The counting mechanism consequently functions in a very reliable manner.

In one variant, the cutting disk is realized for the purpose of severing a segment from the locking pin continuation when the locking pin is moved relative to the cutting disk. The cutting disk then severs the portion of the locking pin continuation which extends between the cutting disk and the contact surface from the remainder of the same. The cutting disk is realized with sharp edges for this purpose. Once said segment has been severed, the locking pin continuation, and consequently the locking pin, is displaced by the length of the severed segment in the direction of the contact surface. The locking pin is moved, in this case, at least in part out of the retaining opening. After the displacement, the former cutting surface abuts against the contact surface. A simple mechanism for controlling the locking pin in dependence on twisting the torsion rod is consequently provided.

The segment can be defined in the locking pin continuation by a notch, wherein the separation is preferably effected in the region of the notch. Multiple notches can also be present so that multiple segments can be defined. The cutting disk preferably carries out the separation of the segments in the region of the notch. At said points it is a reduced material thickness of the locking pin continuation that has to be severed so that a lower separating force needs to be applied by the cutting disk. A segment width, that is to say the distance between a contact-surface-side end of the locking pin continuation and an adjacent notch and/or the distance between two adjacent notches, preferably corresponds, in this case, to the distance between the contact surface and the cutting disk. Low-resistance and low-noise separation of segments can be ensured in this way.

One or multiple segments is or are preferably severed in the stopped state so that the locking pin is removed from the retaining opening. The locking pin continuation, in this case, is shortened by so many segments that when the contact-surface-side end of the locking pin continuation abuts against the contact surface, the locking pin is no longer able to be situated in the retaining opening. The locking pin then releases the pawl in a controlled manner so that the stopped state of the stopping mechanism is set. A high level of passenger safety is consequently ensured.

In addition, no segments or so few segments can be severed in the released state that the locking pin is arranged in the retaining opening. The contact-surface-side end of the locking pin continuation always abuts, in this case, against the contact surface. The locking pin continues to secure the pawl and the stopping mechanism is in the released state.

In one embodiment, the counting mechanism includes a triggering disk which is arranged substantially coaxially to the torsion rod and is connected non-rotatably to the locking-mechanism-side end of the torsion rod, wherein the triggering disk comprises a retaining surface, which extends substantially around the torsion rod and against which, with the stopping mechanism in the released state, abuts against an end of the locking pin which is remote from the pawl, and wherein the triggering disk includes an indentation which interrupts the retaining surface and in which the end of the locking pin remote from the pawl engages in the stopped state. The retaining surface and the indentation are preferably supplemented to form a ring which extends fully around the torsion rod. The pawl-side end of the locking pin is therefore retained inside the retaining opening as a result of the end of the locking pin remote from the pawl abutting against the retaining surface. The indentation, in this case, is designed such that the pawl-side end of the locking pin is removed or slips out from the retaining opening when the end of locking pin remote from the pawl engages in the indentation. Reliable release of the pawl and consequently smooth functioning of the counting mechanism is consequently ensured.

In one variant, the retaining surface extends around the torsion rod substantially by between 290° and 310°, in particular by between 298° and 302°, and/or the indentation extends around the torsion rod substantially by between 50° and 70°, in particular by between 58° and 62°. In a particularly preferred embodiment, the retaining surface extends around by 301° and the indentation extends around by 59°. By fixing the rotational angle assigned to the retaining surface, it is possible to define the rotational angle or torsional angle of the belt-reel-side end of the torsion rod in relation to the locking-mechanism-side end of the torsion rod at which the belt force limitation ends and the belt-reel-side is to be fixed to the frame. The torsional angle corresponds, in this case, substantially to the rotational angle of the retaining surface.

The locking pin is preferably pre-stressed in the direction of the triggering disk, in particular is pre-stressed by means of a spring. This consequently ensures that the locking pin abuts reliably against the retaining surface and consequently also engages reliably in the indentation as soon as the torsion rod is twisted by the predefined torsional angle. The counting mechanism functions securely and reliably as a result.

In an alternative, the locking pin extends substantially parallel to the torsion rod and is mounted on the belt reel. Consequently, the locking pin rotates together with the belt-reel-side end of the torsion rod. The end of the locking pin remote from the pawl slides, in this case, within the released state in the circumferential direction on the retaining surface.

DESCRIPTION

FIG. 1shows a belt retractor10having a belt reel14which is mounted so as to be rotatable in a frame12. The belt reel14, in this case, can be rotated in the frame12in an unwinding direction16and a winding direction18, which is in the opposite direction to the unwinding direction16. Webbing is not shown for reasons of clarity.

The belt retractor10includes furthermore a locking mechanism20, a stopping mechanism22and a belt force limiting mechanism24(see for exampleFIGS. 5 and 6).

In this case, the locking mechanism20and the stopping mechanism22are arranged on opposite sides of the belt reel14.

The locking mechanism20, which is not shown in detail, serves for the purpose of setting up a locked state in a webbing-sensitive and/or vehicle-sensitive manner and thus of blocking a rotational movement of the belt reel14relative to the frame12in the unwinding direction16.

In the locked state, a locking-mechanism-side end26of a torsion rod28is fixed non-rotatably in the unwinding direction16on the frame12for this purpose. This is effected on the side of the frame12on which the locking mechanism20is arranged. The torsion rod28is therefore operatively connected to the locking mechanism20.

The belt force limiting mechanism24, which limits the force acting on the passenger, then acts in the locked state. This occurs as a result of the torsion rod28being twisted.

A belt-reel-side end30of the torsion rod28, which is always non-rotatably connected to the belt reel14, is rotated relative to the locking-mechanism-side end26for this purpose.

The stopping mechanism22is set up for the purpose of fixing the belt reel14on the frame12by means of a clutch32, the clutch32fixing the belt reel14on the side of the frame12on which the stopping mechanism22is arranged.

The stopping mechanism22is then in a stopped state. This is always set up when the belt-reel-side end30is twisted by a predefined number of revolutions in relation to the locking-mechanism-side end26and the locking mechanism20is situated in the locked stated.

A counting mechanism33, in this case, records whether the predefined number of revolutions has been reached. The counting mechanism33also sets up the stopped state of the stopping mechanism22.

A housing part, which covers the stopping mechanism22, has been left out fromFIG. 2so that an actuating disk34of the clutch32is visible. A toothing36, which interacts with a pawl38of the stopping mechanism22, is arranged in the actuating disk34.

The pawl, in this case, is pivotably mounted on the belt reel14.

With the stopping mechanism22in a stopped state (seeFIG. 4), the pawl38engages in the toothing36of the actuating disk34. The actuating disk34is then entrained via the pawl38and rotated in such a manner that the clutch32is closed and the belt reel14is fixed on the frame12. This is effected such that the belt reel14is at least no longer able to rotate in the unwinding direction16in relation to the frame12.

With the stopping mechanism22in a released state (seeFIG. 3), the pawl38does not engage in the toothing36. The clutch32consequently remains open and the belt reel14is able to rotate freely in the frame12, at least as regards the stopping mechanism22.

In the released state, the pawl38is retained by a locking pin40, which is arranged in a retaining opening42of the pawl38. The locking pin40, in this case, is mounted so as to be displaceable in the belt reel14.

The locking pin40is removed from the retaining opening42in the stopped state.

The pawl38, in this case, is acted upon by a spring44in the direction of the toothing36of the actuating disk34. This means that the pawl38is pretensioned in the direction of the locked state.

The stopped state is set up when the belt-reel-side end30is rotated by a predefined number of revolutions in relation to the blocking-mechanism-side end26with the blocking mechanism20in the blocked state. The torsion rod28is the twisted by the predefined number of revolutions.

The counting mechanism33is explained below by way of various embodiments. The counting mechanism33is set up for the purpose of removing the locking pin40from the retaining opening42when the predefined number of revolutions has been reached.

In a first embodiment of the belt retractor10shown inFIGS. 5-8, the counting mechanism33is based on a thread50.

The thread50is connected to the locking pin40at one end. The thread50is connected to a winding disk52at its other end.

The winding disk52, in this case, is connected non-rotatably to the locking-mechanism-side end26of the torsion rod28. It is additionally arranged substantially coaxially to the torsion rod28.

The winding disk52can be arranged furthermore on a locking disk (not shown in any detail) of the locking mechanism20.

The released state of the stopping mechanism22is shown inFIGS. 5-8. This means that the thread50includes a thread reserve53which is arranged between the winding disk52and the locking pin40but is not tensioned.

With the stopping mechanism22in a stopped state (not shown in any detail), the thread reserve53is so small that the thread50is tensioned between the winding disk52and the locking pin40and the locking pin40is removed from the retaining opening42by means of the thread50.

The thread can be arranged, in this case, in a housing54which is connected non-rotatably to the belt reel14. The locking pin40is also situated at least in part in the housing54in the stopped state.

The stopping mechanism22and the counting mechanism33of the first embodiment of the belt retractor10function as follows.

In a released state, the locking pin40is situated initially in the retaining opening42of the pawl38. The thread reserve53of the thread50rests loosely inside the housing54.

If the locked state of the locking mechanism20is then set up, that is to say the locking-mechanism-side end26of the torsion rod28is fixed to the frame12, the belt reel14is only able to be rotated in the unwinding direction16within the framework of the belt force limitation still with the torsion rod28under torsion.

In the case of said rotation, the thread50is wound onto the winding disk52as the winding disk52is also rotated relative to the locking pin40and consequently the two ends of the thread50are rotated relative to one another.

The length of the thread reserve53, that is to say also the length of the thread50overall, is matched in this case such that at a predefined number of revolutions, the thread50is tensioned between the winding disk52and the locking pin40and the thread50pulls the locking pin40out of the retaining opening42. The locking pin40then rests at least in part inside the housing54.

The pawl38then engages in the toothing36and the stopping mechanism22is in the stopped state.

A second embodiment of the belt retractor10is shown inFIGS. 9-12

In this embodiment the counting mechanism33differs from that of the first embodiment.

The counting mechanism33here includes a latching continuation56which is realized on the locking pin40and is produced in one piece with the locking pin40.

A latching toothing58, via which the latching continuation56interacts with a latching element60, is arranged on the latching continuation56. The latching element60includes a latching-continuation-side end62, which can be a resilient latching arm, for this purpose.

Furthermore, the latching element60interacts with an actuating disk64. An actuating-disk-side end66is provided on the latching element60for this purpose.

The latching element60is pretensioned in the direction of the actuating disk64by means of a spring68so that the latching element60, more precisely the actuating-disk-side end66, always abuts against an actuating contour67of the actuating disk64.

The actuating disk64is coupled non-rotatably with the locking-mechanism-side end26of the torsion rod28and is arranged coaxially thereto. In this case, the actuating disk64can be arranged in particular on a locking disk of the locking mechanism20.

The latching continuation56, the latching element60and the spring68are preferably arranged in a housing69which is mounted non-rotatably on the belt reel14.

The latching element60and the latching continuation56extend substantially parallel inside the housing.

The method of operation of the second embodiment is as follows.

Proceeding with the stopping mechanism22in a released state, in which the locking pin40is arranged at least in part in the retaining opening42of the pawl38, the locking mechanism20is moved in a locked state.

The locking-mechanism-side end26of the torsion rod28is therefore fixed in the frame12of the belt retractor10.

If, within the framework of the belt force limitation, the belt-reel-side end30of the torsion rod28is rotated in relation to the locking-mechanism-side end26, the latching continuation56and the latching element60are rotated relative to the actuating disk64and the actuating contour67.

On account of the spring loading provided by the spring68, the actuating-disk-side end66of the latching element60always abuts, in this case, against the actuating contour67of the actuating disk64.

In dependence on the actuating contour67, the latching element60can then be displaced relative to the latching continuation56in opposition to a direction of extraction70of the locking pin40. The latching toothing58and the latching-continuation-side end62interact, in this case, in such a manner that the latching toothing58is traveled over by the latching-continuation-side end62, i.e. the latching element60is moved70relative to the latching continuation56in opposition to the direction of extraction without moving said latching continuation.

The latching element60, however, always entrains the latching continuation56in the direction of extraction70, i.e. there is no relative movement between the latching element60and the latching continuation56in the direction of extraction70.

The latching continuation56, and consequently the locking pin40, is therefore moved in a controlled manner in the direction of extraction70in dependence on the position of the actuating contour67of the actuating disk64.

The actuating contour67includes a ramp in the embodiment shown see in particularFIG. 12).

If the locking-mechanism-side end26and the belt-reel-side end30of the torsion rod28are rotated in relation to one another in such a manner that the ramp cooperates with the actuating-disk-side end66of the latching element60, the latching element60is displaced in opposition to the force of the spring68. In this case, the latching-continuation-side end62travels over, for example, a tooth of the latching toothing58.

If the actuating contour67is rotated further so that the actuating-disk-side end66no longer engages the ramp, the latching element60is moved back in the direction of the actuating disk64by the spring68. In this case, the latching-continuation-side end62entrains the latching projection56.

In the embodiment shown, with each full relative rotation of the actuating disk64, the latching continuation56, and consequently the locking pin40, is therefore pulled out of the retaining opening42by an increment.

The actuating contour67of the actuating disk64, in this case, is designed such that after the predefined number of revolutions, the locking pin40is removed fully from the retaining opening42. The pawl then engages in the toothing36and the stopping mechanism22is in its stopped state.

A third embodiment of the belt retractor10is shown inFIGS. 13-18. Said embodiment differs from the first and the second embodiment of the belt retractor10with regard to the counting mechanism33.

The counting mechanism33here includes a locking pin continuation72which is arranged on the locking pin40.

The locking pin continuation72extends, in this case, up to a contact surface74which is coupled non-rotatably with the locking-mechanism-side end26of the torsion rod28. It therefore extends substantially over the entire length of the torsion rod28.

The locking pin continuation72is spring-loaded in the direction of the contact surface74so that it always abuts against the contact surface74. The associated spring is not shown in the figures.

Furthermore, said embodiment includes a cutting disk76which is also connected non-rotatably to the locking-mechanism-side end26. The cutting disk76, in this case, is at a spacing from the contact surface74in the direction of the pawl38.

The contact surface74and the cutting disk76can be arranged in particular on a locking disk (not shown further) of the locking mechanism20.

The locking pin continuation72, in this case, is mounted in a guide which is fixed with reference to the belt reel14. The guide can also be arranged, in this case, in a housing (not shown in any detail).

The method of operation of the counting mechanism33is as follows.

Proceeding with the locking mechanism20in a locked state and the stopping mechanism22in a released state where the locking pin40is arranged in the retaining opening42, the locking-mechanism-side end26of the torsion rod28is fixed on the frame12.

The contact surface74and the cutting disk76are consequently also connected non-rotatably to the frame12.

Within the framework of the belt force limitation, however, the belt-reel-side end30, the belt reel14and consequently also the locking pin40and the locking pin continuation72can also be rotated relative to the locking-mechanism-side end26.

In the case of such a rotation, the locking pin continuation72runs circumferentially against the cutting disk76in a predefined position so that a segment77, which corresponds substantially in its length to the distance between the cutting disk76and the contact surface74, is severed from the locking pin continuation72.

The cutting disk76is realized with sharp edges at the corresponding positions for this reason.

The locking pin continuation72is shortened as a result and is moved by a section which corresponds to the length of the severed segment77in the direction of the locking-mechanism-side end26.

The cutting disk76, the locking pin continuation72and the contact surface74are set up, in this case, such that after the predefined number of revolutions a sufficient quantity of segments77are severed from the locking pin continuation72so that the locking pin40is removed from the retaining opening42.

The pawl38then engages in the toothing36and the stopping mechanism22is situated in the stopped state.

The segments77of the locking pin continuation72which are to be severed individually can be separated from one another by notches78. The cutting disk76then severs the segments77from the remainder of the locking pin continuation72preferably in the region of the notches78.

FIGS. 19 to 26show a fourth embodiment of the belt retractor10.

In this case, the counting mechanism33includes a triggering disk80which is arranged substantially coaxially to the torsion rod28and is connected non-rotatably to the locking-mechanism-side end26of the torsion rod28.

The triggering disk80can be formed integrally with other components of the locking mechanism20.

The triggering disk80comprises a retaining surface82which extends substantially around the torsion rod28and against which, in the released state, an end of the locking pin40remote from the pawl38abuts (see in particularFIG. 20andFIG. 21).

In addition, the triggering disk80includes an indentation84which interrupts the retaining surface82and in which the end of the locking pin40remote from the pawl38engages in the stopped state (see in particularFIG. 22andFIG. 23). This results in the locking pin no longer engaging in the retaining opening42of the pawl38and releasing it.

In the embodiment shown inFIGS. 19 to 26, the retaining surface extends around substantially 301°. The indentation84supplements this to form a full ring, extending therefore substantially 59° around the torsion rod28.

The locking pin40is pretensioned by means of a spring86in the direction of the triggering disk80. Consequently, the end of the locking pin40remote from the pawl38always abuts reliably against the retaining surface82or the indentation84.

The spring86, in this case, can act on a collar88which is provided on the locking pin40.

Additionally, in the present embodiment, the spring86is arranged in a housing90which is mounted on the belt reel14and is preferably produced from plastics material.

At the same time, the locking pin40extends substantially parallel to the torsion rod28and is mounted on the belt reel14.

The pawl38is additionally retained in the present embodiment by means of a safety element92.

The safety element92, in this case, serves for the bearing arrangement of the pawl38and of the end of the locking pin40which engages in said pawl. In this case, the safety element92is not specific to the fourth embodiment. It is able to be used in conjunction with all named embodiments.

In addition, an actuating mechanism of the clutch32is shown in the fourth embodiment of the belt retractor10. Said actuating mechanism is also able to be used in conjunction with all embodiments.

It includes a first actuating disk34a, a second actuating disk34band a third actuating disk34cof the clutch32. In this case, the third actuating disk34cis interposed between the first actuating disk34aand the second actuating disk34b.

The toothing36, in which the pawl38engages in the stopped state, is provided on the first actuating disk34a.

In the stopped state, the first actuating disk34ais rotated by a predefined first rotational angle in relation to the second actuating disk34band both actuating disks34a,34bare rotationally coupled in an actuating direction of the clutch32.

Additionally, in the stopped state, the third actuating disk34cis rotated by a predefined rotational angle in relation to the first actuating disk34aand the third actuating disk is rotationally coupled with the first actuating disk34ain the stopped state in an actuating direction of the clutch32.

The same applies to the second and the third actuating disks34b,34c: In the stopped state, the second actuating disk34bis rotated by a predefined third rotational angle in relation to the third actuating disk34cand the second actuating disk is rotationally coupled with the third actuating disk34cin an actuating direction.

Proceeding from the first actuating disk34awhich is rotationally blocked by means of the pawl38, the clutch32is therefore actuated by means of the second actuating disk34band the third actuating disk34c, that is to say is transferred into a state in which it fixes the belt reel14to the frame12.

With the stopping mechanism22in the released state, the first actuating disk34ais rotatable by the predefined first rotational angle in relation to the second actuating disk34bin the actuating direction of the clutch32.

The third actuating disk34cis also rotatable in the released state by the predefined second rotational angle in relation to the first actuating disk34ain the actuating direction of the clutch32and the third actuating disk34cis rotatable by the predefined third rotational angle in relation to the second actuating disk34b.

The first, the second and the third rotational angles consequently supplement the rotational angles about which the torsion rod28is able to be rotated before the clutch32fixes the belt-reel-side end30to the frame12.

In other words, the actuating disks34a,34b,34crealize a secondary counting mechanism, by means of which the angles or numbers of revolutions which can be recorded by means of the counting mechanism33are able to be supplemented.