Patent ID: 12235149

DETAILED DESCRIPTION OF THE INVENTION

InFIG.1a vehicle wheel for a passenger car or a commercial vehicle is designated altogether with reference sign1, which has in a manner known per se a rim part2, which can be of any construction or design type and is connected or formed with an unrepresented dish part, by means of which the vehicle wheel1comprising the key part and rim part can be connected to the hub of a vehicle. The vehicle wheel can be composed of a separately manufactured rim part and bowl part, but it can also consist of a single cast part. The rim part2has two rim shoulders3,4to support a tyre not shown, between which there is a rim drop centre5with two drop centre sides6,7. The visible surface of rim part2inFIG.1forms its outer circumferential or lateral surface, which is symmetrical around a wheel axis. In the design example shown, in the area of the rim drop centre5on the outer circumferential surface of the drop centre, a monitoring device designated as a whole with reference sign10is attached to two fastening zones spaced apart from each other in the circumferential direction of the drop centre, in such a way that the monitoring device extends with its longer axis in the circumferential direction. The attachment of the monitoring device10to the drop centre floor of the rim drop centre5, in particular near the outer drop centre flank6, i.e. facing away from the wheel hub, forms the preferred mounting position for the monitoring device10; however, the monitoring device10could also be attached to other areas of the rim part2. When tyres are fitted, the monitoring device10is located in the pressure-loaded interior of the tyre.

FIGS.2and3show the monitoring device10in perspective view and sectional view according to a first embodiment. As can be seen, the monitoring device10has a housing11, which is not directly but only indirectly connected to the rim drop centre5, because the housing11is fastened to an adapter plate30, which itself is fastened to the surface of the rim drop centre5, in particular glued in. The adapter plate30has a base side31which is precisely adapted to the curvature of the drop bed base of the rim drop bed5and thus lies flat against the drop bed base5. The adapter plate30has a cover side32, which is flat in the design example shown, so that the housing11of the monitoring device10itself can have a flat underside12. The advantage of using an adapter plate30is that by using a different adapter plate it is possible to adapt it to different radii of curvature of the rim part, so that the same or each identical monitoring device can also be used on other vehicle wheels with different dimensions.

The mounting between housing11of the monitoring device10and the adapter plate10located underneath is not flat but only on two fastening zones12,13, which are in circumferential contact with each other, and in the design example shown in each case by a cap screw15for each fastening zone12,13, with which the housing11of the monitoring device10is screwed onto the adapter plate30. The adapter plate30therefore has a threaded hole33for each of the two cap screws15, whereby the distance between the two threaded holes33is adapted to the distance between one through hole16in one fastening zone12and another through hole17in the other fastening zone13. In the example shown, a sleeve18is inserted in each of the two through holes16,17and is penetrated by the shank of the cap screw15. The adapter plate30and thus also the monitoring device10are positioned on the rim drop centre in such a way that the two threaded holes33are aligned with a circumferential line parallel to the circumferential direction and thus orthogonal to the wheel axis.

The forces introduced into the rim part as a result of external influences, in particular vehicle weight and load of the vehicle, lead to a deformation of the rim part in the circumferential direction with a maximum in the area of the wheel contact surface, and the monitoring device10with its load detection device is designed to detect these deformations for determining the load forces actually acting on each vehicle wheel by means of a sensor system described below. During a movement of the vehicle, the monitoring device10, which rotates with the vehicle wheel in a fixed motion, reaches the position facing the wheel contact surface per revolution and in this position the maximum of the deformation can be detected per revolution. If in each fastening zone12,13only one screw connection is used to fix the fastening zones12,13to the adapter plate underneath and both screw connections are in contact with each other in the direction of rotation of the vehicle wheel, the deformations can be detected essentially free of transverse forces with a suitable sensor system. For this it is also not necessary for the adapter plate30to lie flat against the rim drop centre5, because it is also sufficient for the detection of deformations if the adapter plate is in contact with the outer circumferential surface of the rim part exclusively in the area of the two fastening zones offset to each other in circumferential direction or below and adjacent to the threaded holes. The intermediate area of the adapter plate could be provided with recesses or retractions, which is advantageous for minimizing the additional weight caused by the adapter plate. Or instead of a one-piece adapter plate, an adapter device with several adapter elements is used.

In order to detect the deformation of the rim part caused by the weight and load forces and to transmit it to external components such as the vehicle electronics or an on-board computer, an electronic circuit20shown here only symbolically inFIG.3above the printed circuit board is arranged in the interior of the housing11of the monitoring device10, which is coupled to a load detection device coupled to at least one pair of strain gauges21and to a transceiver which is not shown in detail and via which the load data detected by the load detection device can be transmitted contactlessly, for example by radio, to the corresponding components external to the wheel. The electronic circuit20is supplied by means of a battery23which is arranged in the interior of the housing11, encapsulated against external influences, and the electronic circuit20may have further sensors, such as a pressure sensor24, an acceleration sensor, a temperature sensor (not shown), an angle sensor or the like, in order to determine further operating data on the associated vehicle wheel and also to determine the position of the monitoring device relative to the wheel contact surface.

With the invention monitoring device10, the load detection device detects the deformations occurring on the housing11between the two fastening zones12,13, in the design example shown between the two axes of the respective cap screws15or the axes of the associated through holes16,17. The greater the distance between the two fastening zones12,13, the better the deformations of the wheel rim in the circumferential direction can be detected. In the design example shown, both fastening zones12,13are therefore located at the opposite ends of the housing11, and the entire electronics, together with any further sensors and the circuit board of the electronic circuit20that may be present, are located between the two fastening zones12,13. However, it would also be possible to arrange the fastening zones12,13at a smaller distance from one another and to arrange the electronic circuit and the receiver completely or partially in areas that do not lie between the two fastening zones12,13.

The load sensing device can be installed and arranged in different ways between the two fastening zones.FIG.4schematically shows the basic principle of the load sensing device in the monitoring device10as shown inFIGS.2and3. As can be clearly seen from the top view of the housing11, the two fastening zones in which the offset through-holes are located are each designed as mounting eyes40,41which are different from one another. The mounting eye40is located near the two strain gages21of the pair of strain gages, the mounting eye41is located remote from the strain gages21. Between the two fixing eyes40,41, the housing11has two outer, web-like side walls42which run parallel to one another and, in the mounting state of the monitoring device10, extend on a vehicle wheel parallel to the circumferential direction of the vehicle wheel. The mounting eye41is integrally connected via several webs43,44to the right ends of the side walls42inFIG.4, whereby the mounting eye41is relatively rigidly connected to the side walls42. The mounting eye40, on the other hand, tapers much more in the direction of a connecting bridge46, which runs perpendicular to the side walls42. The fixing eye40forming the fixing zone12is therefore connected to the fixing eye41forming the other fixing zones13via the connecting web46, the side walls42and the webs43,44. With respect to the mounting eye40, the connecting web46forms two cross struts47A,47B of a cross strut pair, each of the cross struts47A,47B being associated with a strain gauge21. The two cross struts47A,47B each form bending struts in the monitoring device10, into which the deformations of the housing between the two fastening zones12,13or the mounting eyes40,41forming these are introduced, in order to detect the deformations and thus a sensor signal for the load forces by means of the strain gauges21. The deformation capacity of the two cross struts47A,47B, which form the respective bending struts of the load sensing device, is determined by the arrangement of one bending hinge48A,48B each between the foot area49of the fixing eye40and the connecting web46, which forms the cross struts47A,47B with its partial section, and the strain gauges21are positioned opposite to the bending hinges48A,48B, symmetrically with respect to the foot area49of the mounting eye40, in order to detect the greatest caused deformation in the longitudinal direction of the housing free of transverse forces. The two bending hinges48A,48B can, as schematically shown, be formed by notched hinges (solid-state hinges), which are produced by an additional notch at the transition of the foot area49to the cross struts47A,47B. The bending hinges form a flexible mechanism to increase the detectable deformations, as is known to the expert, which is why reference is made to the general specialist knowledge.

In the design example inFIG.4, an additional connecting wall51is formed on both sides between the fixing eye40and the outer end50A,50B of each cross member47A,47B or the adjacent side wall42. The connecting wall51each has a thickness at least 30% lower than the thickness of the side walls42and/or the bending struts in order to reduce the effect of the connecting walls51on the bending struts47A,47B and the bending hinges48A,48B. For further decoupling, the connecting walls51are each provided with a semi-circular rounding52or at least one fold (not shown). In the case of different loads on the vehicle wheel, for example due to different heavy payloads or unequally distributed payloads, the rim part of the respective vehicle wheel experiences different deformations which lead to different deformations of the respective bending struts47A,47B, to which the strain gauges21are assigned. The respective sensor signals of the strain gauge21, which are connected to the electronic circuit20in a suitable way known to the specialist, can be compared with reference values, for example from a lookup table, which are determined beforehand for the respective vehicle in the unloaded state as well as for other predefined states. By correlation with these data, the load forces can then be determined and critical loads or load conditions can be reported to the driver, for example. At the same time, the load data determined with the load sensing device can be fed to other systems, as described in the description at the beginning with reference to the state of the art.

The design example of a monitoring device110shown inFIG.5has essentially the same structure as the previous design example. Also here the strain gauges121are assigned to a pair of cross struts147A,147B, whose bending capacity is significantly increased in response to deformation of the rim part by flexible hinges148as a compliant mechanism at the transition of the mounting eye140into the cross struts147A,147B. The only difference to the previous example is that there is no further connection between the outer ends150A,150B and the load sensing mounting eye140of the mounting zones112. On the mounting eye141or the mounting zone113, however, the housing111of the sensor is designed identically to the previous design example.

FIGS.6and7show another example of a210monitoring device. Here, too, the connection between the housing211of the monitoring device210and a drop centre5of a rim part of a vehicle wheel, shown schematically inFIG.7, is made via an adapter plate30, which can have the same structure as in the previous design example, and via two cap screws215, which penetrate through holes216,217in the two fixing zones212,213of the housing211and are detachable in threaded holes33in the adapter plate30and are therefore screwed in for easy installation and replacement of the monitoring device210. The monitoring device210also has a bending strut247, but this bending strut247extends in a straight line between the two fixing zones212,213, symmetrically to the centre axis or centre of the two fixing holes216,217. In the design example shown, the bending strut247is arranged in the lower, bottom-side area of the interior of housing211near adapter plate30, and housing211forms a hood spanning this area, the printed circuit board of the electronic circuit220together with the battery223being arranged above the bending strut247. The bending strut247has at both ends cylindrically shaped, widened heads260, which are inserted and anchored into cylindrical receptacles261, which are located in the respective foot areas of the two fastening zones212,213of the housing, and which are aligned and symmetrical to a connecting line between the two centres of the fastening holes216,217. The strain gauges221measure the different deflections of the bending strut247which occur due to different deformation of the rim part in the circumferential direction.

FIG.8shows another alternative design example similar to the design example given inFIG.6. Here, too, the two fixing zones312,313, which have the fixing holes316,317for screw or pin connections with an adapter plate, are provided on the rear with a receptacle361for the widened head361of a bending strut347. However, the bending strut347has two arms365A,365B, which span an approximately diamond-like gap and each have a middle section366, which runs parallel to the circumferential direction, albeit laterally offset to the direct connecting line between the two fixing holes316,317, and is connected via inclined sections367to the respective head361at the end of the bending strut347. Halfway between the two heads360, both center sections366may each have, as indicated by dashed lines, a notch hinge348as a flex hinge or bending hinge to increase the flexibility of the bending strut in the detection region of the strain gages321disposed opposite the flex hinges at the center section366.

FIGS.9to11again shown another alternative embodiment for a monitoring device410fixed to the rim part2of a vehicle wheel. As can be seen fromFIG.9, the monitoring device410is equipped with a housing411being much longer and thinner compared to the other embodiments. Similar as within the previous embodiments, the housing411is attached to the rim part2of the wheel by means of two tap screws415, which penetrate with their screw shank respective through holes416in each of the fastening zones412,413and which are screwed into anchor nuts433, shown inFIG.10, being welded or glued onto the outer circumference of the rim part (2,FIG.9). An optimized fastening is achieved by washers414underneath the cap of cap screws415as well as safety sleeves within the through holes416.

As can be seen fromFIG.9andFIG.10, the housing411comprises in the shown embodiment, a total of three sections, namely a main section411A in the middle, comprising the fastening zones412,413, as well as the bending strut configuration470for detecting the load data, while an electronic circuit420is arranged outside the main section411A in a side section411B being circumferentially offset from the main section411A. In another side section411C, being arranged circumferentially offset to the other side of the main section411A, the battery cell for energy supply of the electronic circuit is arranged, so the entire monitoring device410is much thinner compared to the embodiments inFIG.1-8.

Also, the design and construction of the load strut is different compared to the embodiments inFIG.1-8. As can best be seen fromFIG.11, the load strut, designated in its entirety with470is detachably connected to the fastening zones412,413by means pin-head portions460inserted from above into receptacles461at inner ends of the fastening zones412,413. Both the pin-head portions460and the receptacles461have matching cylindrical parts with a radius or curvature such that the inner radius/curvature R2inside the receptacles461is slightly greater than the outer radius/curvature R1of the pin-head portions460. In addition, the distance of the centres of the pin-head portions460is slightly greater than the distance of the receptacles461so that a tight interference is achieved, locking the load strut470inside the receptacles461between the fastening zones412,413.

The load strut470partly comprises a rectangular bending frame having transverse extending connecting arms481and longitudinal extending bending arms482, with strain gauges421being attached to the longitudinal extending bending arms482. In the shown embodiment, there are four strain gauges421building two pairs, one pair being positioned on the inner side of the longitudinal bending arms482and the other pair attached to the outer side of the longitudinal bending arms482; however, it would be sufficient just to have one pair either on the inner side or on the outer side. Between each of the connecting arms481and the pin-head portions460are integrally formed on the load strut470a pair of triangle formed connecting parts485having a triangle tip486being connected to the connecting arms481, and having a triangle base487, at which the pin-head portions460are formed as extensions.

In order to better or amplify the signal output of the strain gauges421, the bending strut470comprises here three flex hinges448A,448B,448C on the connecting arms481adjacent the triangle tip486, with two of the flex hinges448A,448B being positioned in close vicinity to the connecting foot of the triangle tip486with the connecting arm481, and the third flex hinge448C being positioned opposite the triangle tip486on the inside of the rectangular frame480. Also, in order to minimize influences due to the fixing of the load strut470in the receptacles461on the fastening zones412,413, the contacting area between the pin-head portions460and receptacles461is reduced by gaps between the rounded, fork-like inner front parts of the fastening zones412,413and the triangle base486and the pinhead portions460.

For the expert, the previous description results in numerous modifications which should fall within the scope of protection of the attached claims. Some of the embodiment examples show the fastening of a housing by means of an adapter plate, which is one preferred design example option. The adapter plate could also be in two parts and have two unconnected plate sections each having only one threaded hole for fixing the monitoring device by means of a screw or anchor pin to which one of the fixing zones of the monitoring device housing is fixed. It would also be possible to create two spaced zones, each with a threaded hole or an anchor pin, on the rim part, all with anchor nuts attached to the rim part, as shown in the last embodiment, in a suitable manner in order to detachably attach the housing of the monitoring device to the circumference of the rim part. Each fixing zone could also have several fixing points, preferably distributed symmetrically to the strain gauges of the load sensing device. If there are several fixing points, however, the measurement result may be significantly more falsified due to different clamping forces between the housing and rim part. In addition, the invented sensor could also be equipped with piezo elements and a power generation circuit to increase the service life of the monitoring device.

In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.