Hall sensor arrangement and use of a hall sensor arrangement in a belt lock

Hall sensor arrangement is disclosed for detection of the change in the position of two components which can move relative to one another into two end positions, with a Hall sensor with at least one Hall measurement field (H; H1, H2) and a field magnet. An actuator is provided for transmitting to the Hall sensor the change in the position of the two components which can move relative to one another. The Hall sensor and the field magnet are combined into a preassembled structural unit. When the position of the field magnet changes relative to the Hall sensor from one end position into the other end position the polarity of the magnetic field acting on the Hall measurement field (H; H1, H2) can change, e.g., the polarity becomes reversed.

The invention relates to a Hall sensor arrangement as claimed in the preamble of claim1. The invention also relates to use of the Hall sensor arrangement in a belt lock.

Hall sensors are commonly used as proximity switches or as sensors for contactless determination of the state of components which can assume two positions. In principle, Hall sensors consist of a semiconductor layer supplied with a constant current, usually in an integrated construction. The constant current is influenced by the magnetic field component perpendicular to the semiconductor layer and the sensor delivers a Hall voltage which can be evaluated, which can be tapped, and which can be used to evaluate the state or also directly as an operating voltage. The integrated construction of Hall sensors makes it possible to integrate an evaluation circuit which is suited for evaluation of the operating state on the Hall sensor.

In the automotive industry Hall sensors are used for example as contactless state sensors for the state of the belt locks of safety belts. Knowledge of the belt lock state is necessary to signal to the passengers to put on and lock the safety belts. Since the introduction of airbags information about the locked state of safety belts is also important for control of activation or deactivation of mechanisms for inflating driver and passenger airbags or side airbags.

EP-A-0 861 763 discloses a belt lock with an integrated Hall sensor which detects the state of the locking body or an ejector for a lock tongue which has been inserted into the belt lock, without contact. In a pretensioned sensor version there is a Hall sensor with a Hall field in the immediate vicinity of the field magnet. By changing the position of the locking body and ejector which for this purpose consist of a ferromagnetic material, the magnetic field of the field magnet is changed. This changes the signal of the Hall sensor and at the Hall sensor output the state change can be tapped as a voltage change. In one alternative version, it is proposed that the Hall sensor with the Hall field be installed without a field magnet and for this purpose the locking body or ejector be made as permanent magnets. In this arrangement the change in the position of the locking body or of the ejector will be detectable by a change of the Hall voltage.

The disadvantage in the belt lock as claimed in EP-A-0 861 763 is that the Hall sensor must be positioned very carefully with respect to the locking element or ejector. Subsequent installation of the Hall sensor is therefore relatively complex and expensive. The Hall sensor is moreover relatively sensitive to external stray fields which can be caused for example by a magnetic key chain. Optionally additional shielding must even be mounted; this further complicates attachment or installation. The susceptibility to external stray fields is further exacerbated by the signal changes being relatively small due to the comparative short distances traversed by the locking body and ejector, when the safety belt lock is being closed or opened. The belt lock version without the biased Hall sensor, in which either the locking body or the ejector is made as a permanent magnet, is of low practicality. The relative positioning of the Hall sensor and of the ejector must take place very accurately and is susceptible to vibrations. Demagnetization of the field magnet over time can even occur due to vibrations of the locking body and ejectors when the safety belt is being opened and closed. This can lead to the Hall sensor becoming ineffective and the state changes of the belt lock no longer being detectable.

The object of this invention is to reduce or avoid these disadvantages of the prior art. A Hall sensor arrangement will be devised which enables simple installation and facilitated installation in a belt lock. It will be possible to avoid complex positioning and calibration of the Hall sensor and field magnet in installation. Simple and economical attachment or installation which also promotes retrofitting of existing belt locks of different designs will be enabled. The Hall sensor arrangement will be simple and economical to produce and install.

These objects are achieved by a Hall sensor arrangement which has the features cited in the characterizing section of claim1. Developments and/or advantageous versions of the invention are the subject manner of the dependent claims. To achieve these objects the use of a Hall sensor arrangement as claimed in the invention for installation in a belt lock for a safety belt in a motor vehicle and a belt lock with a Hall sensor arrangement as claimed in the invention are proposed.

The invention suggests a Hall sensor arrangement for detection of the change in the position of two components which can move relative to one another into two end positions, which arrangement comprises a Hall sensor with at least one Hall measurement field and a field magnet. There is an actuator for transmitting to the Hall sensor the position change of the two components which can move relative to one another. The Hall sensor and the field magnet are combined into a preassembled structural unit such that when the position of the field magnet changes relative to the Hall sensor from one end position into the other end position the polarity of the magnetic field acting on the Hall measurement field changes, preferably is reversed.

By combining the Hall sensor and the field magnet into a preassembled structural unit, when using the Hall sensor arrangement, for example in a belt lock, the complex positioning and calibration of the discrete individual components are eliminated for the user. A preassembled structural unit can be used which has an actuator for transmitting to the Hall sensor the change in position of the components which can move relative to one another. The structural unit is advantageously made such that during assembly, the mounting of the individual components, Hall sensor, field magnet and actuator in exact positions is ensured. The arrangement of the Hall sensor and field magnet is chosen such that for a relative displacement of the two components a signal change as large as possible is produced. In this connection the circumstance is used that on the Hall sensor the greatest signal changes occur when the polarity of the magnetic field changes, is preferably even reversed, in the change of the relative position of the field magnet.

When using a Hall sensor arrangement in a belt lock, combining the individual components into a preassembled structural unit ensures that the safety belt manufacturer need not intervene in his production process by installing the Hall sensor arrangement. Installation only takes place after completion of the production process of the belt lock. In installation the Hall sensor arrangement is for example simply slipped onto the frame of the locking mechanism of the belt lock. The actuator as a single component of the structural unit comes into contact with the movable component of the locking mechanism.

In a first advantageous version of the invention, all components of the state sensor are combined in a modular construction. The Hall sensor module in this case is made such that it can be installed later into the belt lock. It comprises a Hall sensor which is arranged fixed in a depression of the module housing, a lever which can be moved into two end positions, with a recess in which the field magnet is fixed, and a compression spring which applies a force to the lever. The lever is bent and projects through a recess out of the module housing. In the assembled state the bent section of the lever interacts nonpositively with the component of the locking mechanism which changes its position upon actuation. By combining all components of the state sensor into a module, their position is largely immaterial, as long as the bent section of the lever interacts to the desired extent with the movable component to be monitored. All adjustments have already been made when the individual components are installed in the module housing. The module is installed entirely in the belt lock and in this way is nonpositively connected to the component which changes its position when the locking mechanism is actuated. Complex subsequent adjustment of the Hall sensor and the field magnet can be eliminated.

By the Hall sensor being made as a differential Hall sensor with two measurement fields, magnetic field differences can be measured with the sensor. In difference formation of the signals delivered from the Hall measurement fields interference effects from external magnetic fields can be very easily eliminated. Due to the extensive invulnerability of the difference Hall sensor to external magnetic interference fields even smaller changes of the magnetic field acting on the difference Hall sensor can be detected. The linear arrangement of the Hall measurement fields behind or next to one another takes into account the circumstance that the movement of the components which are changing their location takes place essentially linearly. In this way the prerequisites are established for optimization of the size of the signal change at the output of the difference Hall sensor.

In a Hall sensor arrangement with a differential Hall sensor which is not biased, the field magnet is advantageously located on a movable component such that its direction of motion when the position of the monitored component changes runs essentially parallel to the linear arrangement of the Hall measurement fields on the Hall sensor. The parallel motion leads to the greatest possible signal change. In movement parallel to the Hall measurement fields the distance of the field magnet from the Hall measurement fields of the differential Hall sensor remains essentially constant. In this way the signal change or the travel alone is a function of the movable component which changes its position, for example the component of a locking mechanism which changes its position when the belt lock is locked.

In one version of the Hall sensor arrangement as claimed in the invention with a differential Hall sensor which is not biased, the field magnet has magnetization which runs essentially perpendicular to the linear arrangement of the Hall measurement fields on the Hall sensor. To increase the signal change or the travel it is advantageous if the field magnet on the movable component has magnetization which runs essentially parallel to the linear arrangement of the Hall measurement fields on the Hall sensor. Preferably the field magnet is located on the movable component such that when its position changes, the two magnet poles are routed past the two Hall measurement fields of the differential Hall sensor. In this way opposite signal changes are caused by the magnetic north and south pole in the two Hall measurement fields. When the signals produced in the Hall measurement fields are subtracted, the signal changes are added and lead to doubling of the signal change detected overall or of the travel.

The Hall sensor arrangement can also have a Hall sensor, for example a differential Hall sensor which is biased. For this purpose there is another permanent magnet as the field magnet in the immediate vicinity of the Hall sensor. The used of a biased Hall sensor even makes it possible to omit a permanent magnet on the actuator. In this simplified version at least the section of the actuator which has been guided past the Hall sensor when the relative position of the two components changes consists of a ferromagnetic material which when the position changes disrupts the magnetic field of the field magnet such that a voltage change can be detected on the Hall sensor.

Another very advantageous version of the invention calls for the Hall sensor and at least one field magnet to be located on an adapter which is made as a monolithic component. The adapter is made such that it can be mounted on the stationary component of the two components which can move relative to one another. The adapter has two adapter parts which are made to be movable relative to one another, one adapter part bearing the Hall sensor and the second adapter part bearing the field magnet. The adapter construction is especially space-saving. No additional components, for example actuators or the like, are required for its operation. The movable adapter part can be positively driven by its being positively and nonpositively connected to the movable component which changes its relative position. In one alternative version the movable adapter part is elastically pretensioned relative to the permanently mounted adapter part. This can be accomplished by the inherent spring force or can be supported by a spring or similar elastic element integrated on the permanently mounted adapter part and the movable adapter part. The elastically pretensioned adapter part then adjoins the component which changes its position to two alternative end positions. The Hall sensor is advantageously located on the permanently mounted adapter part. This facilitates routing of the electrical lines which are also hardly exposed to mechanical stress. The movable adapter part bears the field magnet. The Hall sensor and the field magnet are advantageously arranged such that they have a distance as small as possible from one another. In this way, on the Hall sensor larger signal changes can be achieved.

The Hall sensor can be biased by another field magnet which is located in the immediate vicinity of the sensor. The Hall sensor can also be made in turn as a differential Hall sensor.

The Hall sensor adapter is made especially for use in a belt lock. In this connection the space-saving, flat, monolithic construction is especially advantageous. The Hall sensor adapter can be easily clipped or suspended on the frame of the belt lock. The movable adapter part interacts with a component which changes its position to two end positions when the lock mechanism is actuated. In positive action of the movable adapter part it is for example a rocker which bears a locking body. In the case of a spring-pretensioned adapter part it for example adjoins the rocker or a spring which acts on the locking body.

Relatively large signal levels and thus large signal-to noise-ratios can be achieved by the relative movement of the field magnet to the Hall sensor. The Hall sensor arrangement in the installed state is located on the side of the belt lock facing away from the passenger. This largely prevents any adverse effect by external magnetic fields, for example by a magnet or the like which is located in the pocket of the pants or coat of the passenger. By mounting the Hall sensor arrangement, for example the Hall sensor module or the Hall sensor adapter, in the interior of the belt lock, the surrounding metal components, especially the frame of the belt lock, apply a shielding action against external interference effects. Due to the extensive invulnerability of the Hall sensor arrangement which has been installed in this way, the Hall sensor can be made as a conventional Hall sensor with only one measurement field or as a differential Hall sensor with two measurement fields which are located next to one another. The Hall sensor can also be pretensioned. The Hall sensor arrangement in the form of a structural unit is characterized especially in that modifications of the belt lock for its installation are not necessary. The clipped-on or suspended Hall sensor adapter also largely eliminates rattling noise of the belt lock by suppressing larger relative movements of the rocker which bears the lock part against the frame of the belt lock.

In one feasible version of the Hall sensor adapter, one adapter part has two lengthwise arms with free ends which are provided with retaining hooks. In the installed state, the retaining hooks extend around two vertical members which project roughly vertically from the frame of the belt lock. The lengthwise arms are connected by a cross arm which is made in the manner of clamp and in the mounted state peripherally clamps one end section of the rocker which can be tilted into two end positions. The second adapter part is made as a link which is movably coupled to the cross arm via a hinge joint and which has fasteners for locking to the corresponding counterparts on the rocker. The hinge joint is advantageously made as a film hinge. Film hinges can be easily produced and have a relatively high strength and long service life. Due to the flat execution of the film hinge, deflections laterally are largely avoided. They can be still further limited by lateral stiffening of the film hinge.

The fasteners provided on the link encompass snap hooks which can be routed through a hole of the rocker and can be locked to the rocker. Opposing holders located on the link in the mounted state of the adapter press against the rocker and provide for positive and nonpositive locking of the link to the rocker. This ensures that the link cannot be detached from the rocker even by greater vibrations and operation of the state sensor arrangement is preserved.

In a second version of the Hall sensor adapter, the adapter part which can be permanently installed is made frame-like with holding devices for mounting on the belt lock frame. The second adapter part which moreover forms the actuator has the shape of a movable tongue which is surrounded by the frame and, pretensioned elastically relative to the frame, is connected to the frame part.

The Hall sensor and field magnet can be located permanently or removably on the Hall sensor adapter. In one preferred version the Hall sensor is located in a receiver which is provided on one of the lengthwise arms of the adapter. The field magnet is located in the vicinity of the Hall sensor on the movable adapter part. It goes without saying that the arrangement of the Hall sensor and of the field magnet can also be interchanged.

For reasons of production engineering, the adapter is a monolithic plastic part which can be produced in an injection, casting or injection molding process. The production processes are proven and allow large numbers of pieces in uniform quality with low production tolerances.

The belt lock shown schematically inFIG. 1has a known external structure and is provided overall with reference number1. The belt lock1is located on the end of the belt anchoring3and is used for holding and detachable locking of the lock tongue5which is connected to a safety belt6. The belt lock1has a housing2which is made open on its side facing away from the belt anchoring3. An unlocking button42for the locking mechanism located within the housing2extends over most of the open housing region and leaves an insertion slot41for the lock tongue5free. The locking mechanism locks when the lock tongue5is inserted through the insertion slot41in the tongue recess51. The release of the lock tongue5takes place by actuating the unlocking button42.

The schematic section shown inFIG. 2shows the structure of a belt lock of the prior art with a locking mechanism4located within the housing2for a lock tongue5which has been inserted through the insertion slot41. The locking mechanism4is conventionally made. It comprises a frame21with a guided ejector46which is pretensioned by a compression spring48in the direction of the insertion slot41. On its end facing the insertion slot41the ejector46has a tongue receiver47. The lock tongue5is inserted against the spring force of the compression spring48into the housing2. As soon as it has been inserted so far that the tongue recess51is aligned with a recess22in the frame21, the locking body44which is located on the rocker45moves through the tongue recess51in the direction of the recess22and in doing so fixes the lock tongue5. Release of the lock tongue5takes place by actuating the unlocking button42against the spring force of a pretensioning spring43. In this connection the locking body44is pulled back out of the tongue recess51and the spring-loaded ejector46pushes the lock tongue5in the direction of the insertion slot41. At the same time the ejector46prevents movement of the locking body44in the direction of the recess22in the frame21.

The change in position of the locking body44is detected by a contactless state sensor7which is located on the housing2in the vicinity of the locking body44. The state sensor is a Hall sensor71which is pretensioned by a field magnet73which is located in the immediate vicinity. The output signal of the Hall sensor71is dependent on the magnetic field intensity of the field or bias magnet73. When the locking mechanism4is actuated the locking body44is moved away from the Hall sensor71or toward it. If the locking body44is a ferromagnetic component or is connected to one, the location of the moving locking body44influences the intensity of the magnetic field and thus the magnitude of the signal at the output of the Hall sensor71. The Hall sensor can also be for example a differential Hall sensor.

FIGS. 3 to 7schematically show different versions of the arrangement as claimed in the invention of a Hall sensor71and a field magnet72which can be moved relative to one another from one end position into a second end position. In the versions as shown inFIGS. 3-5the Hall sensor71is made as a differential Hall sensor. The differential Hall sensor71has two Hall measurement fields H1, H2which are located linearly next to one another and allows the formation of difference signals. In this connection interference effects by external magnetic fields which act in general identically on the two Hall measurement fields H1, H2are cancelled. By using a differential Hall sensor71the sensor arrangement therefore is largely insensitive to effects of external magnetic interference. The signal which results when the difference is found is a direct measure of the change in the position of the field magnet and thus the change in the position of a monitored component. The signal can be evaluated or used for triggering other operating processes.

In the use of the Hall sensor arrangement as claimed in the invention in a belt lock, when the locking mechanism is actuated displacement D of the field magnet72takes place parallel to the linear arrangement of the Hall measurement fields H1, H2next to one another or in succession. The magnitude of the attainable output signal depends among others on the magnetization J of the field magnet72which has moved past the differential Hall sensor71. In the arrangement as shown inFIG. 3the field magnet72is magnetized perpendicular to the linear arrangement of the two Hall measurement fields H1, H2of the differential Hall sensor71. In the first end position shown solid inFIG. 3for example the magnetic south pole of the field magnet72is facing the differential Hall sensor71. In this first end position the magnetic south pole of the field magnet72influences the Hall measurement field H1of the differential Hall sensor71much more strongly than the Hall measurement field H2. After displacement D of the field magnet72into the second end position, the magnetic south pole of the field magnet72indicated by the broken line influences the Hall measurement field H2of the differential Hall sensor71much more strongly than the Hall measurement field H1. For this position change of the field magnet72, from the viewpoint of the Hall measurement fields H1and H2the polarity of the magnetic field is changed. The signal intensity or travel results from the difference of the signals produced on the two Hall measurement fields.

FIGS. 4 and 5show a second arrangement as claimed in the invention of a differential Hall sensor71and a field magnet72as claimed in the invention. In this connection, the two alternative end positions of the field magnet72relative to the differential sensor71are shown in separate figures. Magnetization J of the field magnet72this time proceeds parallel to the linear arrangement of the two Hall measurement fields H1, H2of the differential Hall sensor71. In the version shown inFIG. 4, the magnetic south pole of the field magnet72first of all influences the Hall measurement field H2of the differential Hall sensor71. The Hall measurement field H1is located in the vicinity of the lengthwise center of the rod-shaped field magnet71and experiences a resulting magnetic field intensity near zero. After the position of the field magnet72changes to the second end position shown inFIG. 5, the magnetic north pole of the field magnet72now influences the Hall measurement field H1of the differential Hall sensor71much more strongly than the Hall measurement field H2. The latter now experiences a resulting field intensity near zero due to its location in the vicinity of the lengthwise center of the rod-shaped field magnet72. In the relative change in the position of the field magnet72to the differential Hall sensor71the magnetic north pole of the field magnet72in the measurement field H1produces a signal change opposite the influence of the magnetic south pole on the measurement field H2. The Hall measurement fields H1and H2undergo a change of the polarization of the acting magnetic field when the position of the field magnet changes. When the two signals are subtracted, the signal changes are added and the signal intensity or the travel is doubled relative to the version as shown inFIG. 3. The arrangement shown inFIGS. 4 and 5is especially advantageous in the detection of very small position changes.

FIGS. 6 and 7show an arrangement of a Hall sensor71and a field magnet72analogous to the version inFIG. 4andFIG. 5. The magnetization J of the field magnet72runs in turn parallel to the surface of the sole measurement field H of the Hall sensor71. In the first end position shown inFIG. 6, the Hall measurement field H is exposed for example to the south pole of the field magnet72. In the second end position as shown inFIG. 7, the Hall measurement field is exposed to the north pole of the field magnet72. The Hall measurement field thus experiences reversal of the polarization of the magnetic field. The resulting signal change can be evaluated or used for triggering further switching processes.

The field magnet72is advantageously a permanent magnet made as a bar magnet. The Hall sensor or the differential Hall sensor71is advantageously made in an integrated design. In this connection for example the evaluation circuit and other circuit components necessary in any case for further processing of the detected signals are preferably already integrated on the component.

FIG. 8shows a schematic section of a belt lock which has been long known in the prior art and which is provided overall with reference number1. The structure of the belt lock1has great similarities to the version shown inFIG. 2. The locking mechanism located within the housing2in turn overall bears reference number4and encompasses a frame21and a locking body44which is located on a rocker45and which in this embodiment is made as a locking hook44projecting from the rocker45. The possibilities of movement of the rocker45into its two end positions are indicated by a double arrow. In the opened state the locking hook44lies on the ejector46which is exposed to the force of the compression spring48. When the lock tongue5is inserted the ejector46is pushed against the reset force of the compression spring48and the locking hook44drops through the tongue recess51and the recess22of the frame21.

FIGS. 9-13show a Hall sensor arrangement combined into a structural unit as claimed in the invention and provided overall with reference number7. In contrast to the belt locks of the prior art (FIG. 2) in which the Hall sensor and the field magnet are mounted as individual components separately in the belt lock, the Hall sensor arrangement7as claimed in the invention is made as a Hall sensor module in which all the components necessary for operation are located in a common module housing70which can be closed with the housing cover77. The individual components of the Hall sensor arrangement7are a Hall sensor71which is located fixed in the housing depression, for example a differential Hall sensor with Hall measurement fields H1and H2, and an actuator which is made as a lever74with a recess75in which a field magnet72is fixed. A compression spring76which is located within the module housing70and which is supported on the one hand in the module housing70and on the other on the lever74acts on the lever74. A section of the lever projecting through a recess79out of the module housing70is bent in the manner of a hook. There is a lengthwise rib78or similar projections on the bottom of the lever section projecting out of the module housing70.

The Hall sensor arrangement7assembled in a modular manner encompasses all components which are necessary for detection of the change in the position of two components which can move relative to one another. The Hall sensor71and the field magnet72are in a three-dimensional relation which can be exactly dictated. The size of the module is such that it can subsequently be easily integrated into the belt lock. The function of the Hall sensor module7is shown in the schematics inFIGS. 12 and 13using the example of the belt lock as shown inFIG. 8.FIG. 12shows the belt lock in the opened state.FIG. 13shows the state of the locked belt lock. When the passenger is being belted the lock tongue is pushed into the lock housing and the ejector46is pushed according to arrow L. In doing so a spring-loaded rocker45tilts, and a locking body44connected to the rocker45moves into the position shown inFIG. 13. The Hall sensor module7is located in the belt lock such that the section of the lever74projecting out of the module housing70extends over the rocker45. The compression spring76which is located within the module housing70and which is compressed in the initial state as shown inFIG. 14presses the lever74by its pretensioning against the bottom of the module housing70. When the compression spring76is released, the lever74necessarily follows the tilting motion of the rocker45(FIG. 13). The field magnet72which is fixed in the recess75of the lever74goes along with the movement of the lever74and is moved past the Hall measurement fields H1, H2of the differential Hall sensor71. The change in the magnetic field which occurs in doing so is detected and the signal “passenger belted” is generated therefrom for example.

When the belt is released, the lock tongue is pulled out of the lock housing. In doing so the ejector according to arrow R inFIG. 13is pressed back into the initial position fromFIG. 12. The locking body44on the rocker45is released and tilts back into the initial position shown inFIG. 12. The lever74which is guided desmodromically in the Hall sensor module7is entrained by the rocker45and migrates up in the module housing70. In doing so that the compression spring46is compressed again. In this motion of the lever74the field magnet72is moved past the Hall sensor71which is located stationary in the module housing70. The Hall measurement fields H1, H2detect the change of the magnetic field intensity and produce a signal, for example “passenger not belted”.

The rib78which is provided on the bottom of the section of the lever74projecting out of the housing module provides for linear support of the lever74on the rocker45. This design is less susceptible to dirt and prevents wedging of the lever74.

In a version of the Hall sensor arrangement made as a Hall sensor module which is not shown separately, the field magnet can be located in the immediate vicinity of the stationary Hall sensor and can likewise be mounted stationary. In this Hall sensor arrangement the field magnet forms a bias magnet for the Hall sensor. If the section of the lever which has moved past the Hall sensor consists of a ferromagnetic material, in this version of the Hall sensor module an additional field magnet mounted on the lever can be omitted, since the change in the position of the ferromagnetic section of the lever leads to detectable magnetic field changes. For the attainable signal changes however for a biased Hall sensor which can also be a differential Hall sensor it is advantageous if the lever bears a permanent magnet.

FIG. 14shows another belt lock known from the prior art without the surrounding housing. The belt lock is in turn provided with reference number1. The locking mechanism is held in a belt lock frame21. The locking mechanism4in turn comprises a rocker45and an ejector46pretensioned by the compression spring48in the direction of the insertion slot. The unlocking button is indicated at42. The rocker45is provided for reasons of weight with a hole49on its end section facing away from the insertion slot. To prevent rattling noise, there is a spring clip9. It has two clip arms91and a crosspiece93which is made in the manner of a clamp and which connects the clip arms91. The ends of the clip arms91are made as hooks92. The spring clip9is on the one hand anchored via hooks92on the vertical members23which project vertically out of the frame21. The crosspiece93made in the manner of a clamp encompasses the end section of the rocker45which is provided with a hole49. The spring clip9limits or prevents relative movements of the rocker45relative to the frame21. Rattling noise of the belt lock1is thus largely prevented.

FIG. 15shows in a representation analogous toFIG. 14a second version of the Hall sensor arrangement as claimed in the invention using the example of a Hall sensor adapter8mounted in a belt lock. In this connection, for reasons of clarity the compression spring (reference number48inFIG. 4) is not shown. The belt lock is in turn provided with reference number1.FIGS. 16 and 17show other views of the belt lock as shown inFIG. 15provided with the Hall sensor adapter8. As is directly apparent from the figures, the Hall sensor adapter8is installed instead of the spring clip (reference number9inFIG. 14). The Hall sensor adapter8bears a preassembled Hall sensor71and a field magnet72.

The adapter8shown enlarged inFIGS. 18 and 19in two views has a first adapter part in the form of two lengthwise arms81which are connected by the cross arm83made in the manner of a clamp. The lengthwise arms81extending in the direction of the insertion slot are provided on their ends with retaining hooks82. The retaining hooks82are used to anchor the vertical members23projecting vertically from the belt lock frame21. Shoulder-like projections on the vertical members23prevent unintentional release of the anchoring of the hooks82from the vertical members23. The cross arm83made in the manner of a clamp surrounds the end section of the rocker45. In this way larger relative movements of the rocker45relative to the belt lock frame21are suppressed and rattling noise is largely prevented.

A second adapter part in the form of a link85projects from the cross arm83of the adapter8and extends in the direction of the lengthwise arms81. The link85is movably coupled via a hinge joint84, preferably a film hinge, on the cross arm83of the adapter and forms the actuator of the Hall sensor arrangement made as a Hall sensor module8. From the bottom of the link a snap hook88projects and extends through the hole49in the end section of the rocker45and reaches positively behind it. An opposing holder89opposite the snap hook88is supported on the surface of the rocker45. In this way the movably connected link85is fixed positively and nonpositively on the rocker45. The fixing of the link85on the rocker45is preferably detachable.

One of the lengthwise arms81of the adapter8has a receiver86for a Hall sensor71. For example, the receiver86is made as a slot into which the Hall sensor71which can be made as a Hall sensor with one measurement field or as a differential Hall sensor with two measurement fields located next to one another can be inserted and can be fixed with respect to its position. Signal lines connect the Hall sensor71to an evaluation device. On the free end of the link85there is a holding device87for a field magnet72of the Hall sensor arrangement. The field magnet72is located within very narrow production tolerances of the adapter8in an exactly definable position relative to the Hall sensor71. By additionally inserted spacers the play of the air gap between the receiver84for the Hall sensor71and the holding device for the field magnet72can be limited and a set operating threshold can be ensured. The link85which is movably coupled to the hinge joint84by the connection to the rocker45goes along with its up and down motion by positive action when the belt link is locked or unlocked and moves relative to the lengthwise arms81which are anchored on the vertical members29. In this movement of the link85the field magnet72is moved in relative terms past the Hall measurement field(s) of the Hall sensor71which is mounted on the stationary lengthwise arm. The change in the magnetic field which occurs here is detected, relayed via the signal lines to the evaluation means and the signal “passenger belted” or “passenger not belted” for example is generated from it.

The Hall sensor can be a Hall sensor with only one Hall measurement field or a differential Hall sensor. An additional field magnet can also be mounted in the immediate vicinity of the Hall sensor in order to bias the Hall sensor.

FIGS. 20 and 21show two views of another embodiment of a Hall sensor arrangement made as a Hall sensor adapter. The Hall sensor adapter in turn overall bears reference number8and comprises a frame-like first adapter part801and a second adapter part which can be moved relative to the frame-like first adapter part801, the second adapter part in the form of an arm805coupled to the frame part803. The movable arm805is surrounded by the frame-like first adapter part801. Two side parts802which run in the lengthwise direction are on the one hand connected by the frame part803, from which the movable arm805projects. On the opposing side, in the vicinity of the free end of the movable arm805, the side parts802are connected by a transverse part804. As is apparent fromFIGS. 20 and 21, the movable arm805has elastic pretensioning relative to the frame-like first adapter part801. The elastic pretensioning of the movable arm805is dictated by the construction and material and can be supported by a spring element which is integrated into the frame part803and the movable arm805.

The frame-like first adapter part801is equipped with holding devices806,807, by which the first adapter part801can be mounted on the stationary component. The holding devices806,807are specifically matched to the component to which the first adapter part801is to be connected. The Hall sensor adapter8shown inFIGS. 20 and 21is for example made for installation in a belt lock. Accordingly the holding devices806,807are made such that the first adapter part810can be mounted for example on a belt lock frame. The elastically pretensioned movable arm805with the Hall sensor adapter8mounted adjoins the component which changes its position. When the Hall sensor adapter8is used in a belt lock, the movable arm805with low pretensioning adjoins the component of the locking mechanism which changes its position into two end positions in the closing or opening process. For example, it is a rocker (FIG. 14) which carries a locking element (FIG. 14) or a spring which acts on a rocker or another locking element. The Hall sensor71which can also be a differential Hall sensor is located on the frame-like first adapter component801. In this embodiment the Hall sensor71is mounted on the transverse part804. But it can also be mounted in the vicinity of the free end of the movable arm805on one of the side parts. The field magnet72is located on the free front end of the elastically pretensioned, movable arm805.

The Hall sensor adapter is a plastic part which is produced for example in a plastic injection or plastic casting or plastic injection molding process. This allows production with very small production tolerances. In the Hall sensor adapter as shown inFIGS. 18 and 19, the hinge joint can be made for example as an integral film hinge. In the Hall sensor adapter as shown inFIGS. 20 and 21, the spring element which supports the elastic pretensioning of the actuator which is made as a movable arm can be embedded in the plastic material. The field magnet and the Hall sensor can also be embedded directly into the plastic material. By lateral stiffening of the film hinge, lateral hinge deflections can be further limited. On the holding devices and holding elements of the adapter which are used for anchoring, there can be other stiffening to ensure reliable anchoring. The adapter can be anchored detachably or captively on the frame and on the rocker (FIG. 17). The Hall sensor and the field magnet can be located fixed or removably on the adapter. It goes without saying that the arrangement of the Hall sensor and of the field magnet can also be interchanged. In this case the Hall sensor is moved relative to the stationary field magnet when the rocker moves. But due to the stresses which however may occur on the signal lines connected to the Hall sensor, the reverse arrangement is preferred.

The Hall sensor adapter has an especially space-saving construction. For its operation it uses only the movable components which are present anyway in the belt lock, especially the motion of a rocker which bears the locking body or of the locking body or a spring which acts on the locking body relative to the frame. In this connection is can be very easily installed as a monolithic component, especially can be suspended and clipped in. Relatively large signal levels and thus large signal-to-noise ratios can be achieved by the relative movement of the field magnet to the Hall sensor. The Hall sensor arrangement in the installed state is located on the side of the belt lock facing away from the passenger. This largely prevents any adverse effect by external magnetic fields, for example by a magnet or the like which is located in the pocket of the pants or coat of the passenger. The Hall sensor arrangement located in the adapter is located in the interior of the belt lock. In this way the metallic components surrounding the Hall sensor arrangement apply a shielding action. This arrangement makes it possible to build the Hall sensor arrangement with a conventional Hall sensor with one measurement field or with a differential Hall sensor with two measurement fields. The Hall sensor adapter can also be biased by an additional field magnet. The Hall sensor adapter is also characterized in that modifications of the belt lock is not necessary for its installation. In the installed state the Hall sensor adapter also largely eliminates rattling noise by damping larger relative movements of movable components of the locking mechanism relative to the frame of the belt lock.