Abstract:
A device for fixing to a wheel a module intended to measure and transmit to a receiver, in particular by radio link, at least one quantity characteristic of the state of a tire mounted on the wheel, in particular its inflation pressure, comprising connecting means rigidly connected to the module and means of attaching the connecting means to the wheel, such that the module is fixed radially internally relative to a seat and a hook on the rim of the wheel, and such that the attachment means are fitted to apply the connecting means against the radially inner surface of the rim hook with an adaptable clamping stress of intensity greater than a given value.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a device for fixing a tire monitoring system module to a wheel of a vehicle.  
           [0003]    2. Description of the Related Art  
           [0004]    The Sicurezza Stradale Technology firm&#39;s “Tyre Check” device comprises a module fixed to the wheel disk by two lugs clamped under two consecutive nuts. The module is pneumatically connected to the valve and comprises a radio transmitter linked to a receiver on board. The mode of installation of the lugs under the wheel nuts suffers from the disadvantage of inducing strong vibrations when the nuts are tightened with shock wrenches (shop tightening). These vibrations may damage the electronics of the module. Furthermore, as the axial dimension of the wheels in question increases, the quality of the link between the module and the receiver is degraded because the adjacent rim well and rim hook together with the disk of the wheel form a metal hollow rendering communication by radio link more difficult.  
           [0005]    U.S. Pat. No. 5,285,189 uses a fixation of the module in the rim well. This fixation device comprises a metal strap encircling the rim well of the wheel rim and clamping the module. The position of the module in the rim well is not favorable to good communication by radio link between the module and the receiver in the chassis of the vehicle. That position also involves dangers of damage to the module at the time of mounting or removing tires on or from the wheel bearing the module.  
           [0006]    U.S. Pat. No. 5,838,229 uses a fixation of the module to the foot of a wheel valve. Consequently, the module is likewise arranged inside the tire cavity, substantially in the rim well as before.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    The present invention relates to a device for fixing a tire monitoring system module to a wheel of a vehicle. The tire monitoring module can measure characteristics of the tires, such as, for example, the pressure of the tires. The tire monitoring module is able to transmit at least one quantity characteristic of the state of the tires to a receiver, such as by radio link. The receiver, for example, can be arranged in the chassis of a vehicle.  
           [0008]    One object of the present invention is to provide dependable transmission of electromagnetic signals by radio link between the modules and the receivers, and dependable mechanical fixation of the module to the wheel.  
           [0009]    The device, according to the invention, comprises connecting means rigidly connected to the module and attachment means for attaching the connecting means to the wheel. The device is such that it is adapted to fix the module radially internally relative to a wheel rim seat and hook, and such that the attachment means are adapted to apply the said connecting means against the radially inner surface of said rim hook with an adaptable clamping stress of intensity greater than a given value.  
           [0010]    This module position has the advantage of arranging the module near the axial extremity of the wheel, that is, in a place where the cavity effect of the metallic surroundings of the module will only slightly interfere with radio transmission. This position is also close to the valve opening of the tire, permitting use of a pneumatic connection of very short length, on the order of only a decimeter or so, between the module and the valve opening. The fixation of the wheel module with an adaptable, that is to say adjustable, clamping stress, of the connecting means against the rim hook surface, allows the device according to the invention to be insensitive to the usual variations in shape and thickness of wheel rim hooks. This is a further assurance of dependability of the fixation.  
           [0011]    This fixation device also has the advantage that it can be mounted on any vehicle, without any adaptation or modification of the wheels in question.  
           [0012]    The clamping stress is preferably greater than 2500 N. This has the advantage of ensuring a mechanically dependable fixation of the module.  
           [0013]    According to a preferred embodiment, the connecting means comprise a plate rigidly connected to the module and a connecting piece rigidly connected to the plate and suitable for arrangement against the radially inner face of the rim hook.  
           [0014]    The connecting means may also comprise a single connecting piece rigidly connected to the module and suitable for arrangement against the radially inner face of the rim hook.  
           [0015]    Advantageously, the connecting piece is adapted to come into contact with the radially inner face of the rim hook in at least two areas of support located on either side of the hollow of the rim hook.  
           [0016]    This has the advantage of ensuring a stable fixation of the connecting piece against the inner face of the rim hook.  
           [0017]    According to a preferred embodiment, the attachment means comprise a generally U-shaped fixation “clip” whose first end is intended to come to rest against the radially outer face of the rim hook, and a second end of which is intended to come to rest against the connecting piece. Preferably, the first end of the fixation clip is tapered. This is to ensure that, in service, the outer face of the tire bead adjacent to this end of the clip will not be damaged in case of contact.  
           [0018]    The geometry of the fixation clip may be adapted to develop clamping stresses due to the elastic deformation of the clip of intensity greater than 2500 N when placed around the connecting piece and the radially uppermost face of the rim hook.  
           [0019]    Alternatively, the second end of the fixation clip may comprise a means of applying a given clamping stress between the clip and the connecting piece.  
           [0020]    It is advantageous for the reliability of the fixation device that the direction of application of the clamping stress intersects the opposed branch of the U of the fixation clip.  
           [0021]    Preferably, when the connecting piece has a first face intended to be applied against the radially inner face of the rim hook and a second face opposed to the first, said second face is adapted so that the plane tangent to said second face at the point of application of the clamping stress is substantially perpendicular to the direction of application of said clamping stress.  
           [0022]    The means of applying a given clamping stress may be a setscrew arranged through one end of the fixation clip. This setscrew may have a diameter of 5 mm and be emplaced with a tightening torque greater than 2 N.m.  
           [0023]    In a preferred embodiment, the fixation device according to the invention is intended especially to fix modules to steel sheet wheels for commercial vehicles.  
           [0024]    It is understood that both the foregoing general description and the following detailed description and figures are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate two embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    [0025]FIG. 1 is a front view of a fixation device according to the invention and of a module, mounted on a rim hook.  
         [0026]    [0026]FIG. 2 is a sectional view at II-II′ as indicated in FIG. 1.  
         [0027]    [0027]FIG. 3 is a front view in direction B as indicated in FIG. 1.  
         [0028]    [0028]FIG. 4 is a view of a fixation clip.  
         [0029]    [0029]FIG. 5 is a sectional view, similar to FIG. 1, of a second example of a fixation device according to the invention and of a module, mounted on a rim hook. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    Reference will now be made in detail to the presently preferred embodiments of the invention, which serve to explain the principles of the invention.  
         [0031]    [0031]FIGS. 1 and 2 show a module  1  fixed under a seat  21  of the wheel rim  2  by the fixation device  4  according to the invention. FIG. 2 is a section at II-II′ in FIG. 1.  
         [0032]    In the description, the axis of rotation of the wheel is taken as reference for the “axial” and “radial” directions.  
         [0033]    In FIG. 2, we see a tire bead  3  in place on a seat  21  and hook  22  of a wheel rim  2 . The module  1  is fixed radially under the rim seat  21  by the device  4 . This device  4  comprises connecting means composed of a plate  5 , on which the module  1  is fixed, and a connecting piece  6 . The device  4  also comprises attachment means, which in the present embodiment, comprises a fixation clip  7  and a setscrew  8 .  
         [0034]    The plate  5  is a metal plate with two lugs  51  to be fixed to the connecting piece  6  by two screws  52  (FIG. 1).  
         [0035]    The connecting piece has a first face  61  arranged against the radially inner face  23  of the rim hook  22 . As shown in FIG. 3, the connecting piece  6  has a second face  62  opposed to the first face  61 . The first face  61  is of suitable geometry to be arranged against the radially inner face  23  of the rim hook  22 , in both directions, axial and circumferential, of the rim hook  22 . The second face  62  has two plane lateral parts  63  connecting with the plate  5  and a recessed central part  64 . The plane of symmetry H, shown in FIG. 3, of the connecting piece  6  corresponds to the plane of section of FIG. 2. The connecting piece may advantageously be made of a cast metal alloy.  
         [0036]    [0036]FIG. 4 shows a view of a fixation clip  7  having a generally U-shape with a first end  71  and a second end  72 . In this embodiment, the first end  71  is tapered to come to rest against the radially outer face  24  of the rim hook  22 . The second end  72  has threading  73  intended to receive a setscrew  8 . It is to be noted that the centerline of the thread  73  intersects the second branch of the U. As shown in FIG. 2, the end  81  of the setscrew comes to bear against the central part  64  of the second face  62  of the connecting piece  6 . At the time of fixing the module  1 , the setscrew  8  is applied with a given torque, preferably greater than 2 N.m for a setscrew of 5 mm diameter, resulting in a clamping force greater than 2500 N. This very high stress is necessary in order for the module  1  to remain well in place under service stresses on the wheel and tire. The fixation clip preferably consists of an elastic steel.  
         [0037]    [0037]FIG. 2 also specifies the preferred bearing areas between the parts of the device  4 . The deformation of the fixation clip  7  due to tightening of the setscrew  8  results in clamping stresses in at least two preferred bearing areas of contact. The first area of contact is at C, the area of contact between the ends  81  of the setscrew  8  and the face  64 . At C, for the sake of good transmission of the clamping stress, the plane P tangent to the face  64  is substantially perpendicular to the centerline I of the thread  73 . The direction of application of the clamping stress at C substantially coincides with the centerline I.  
         [0038]    The second area of contact is at D, the area of contact between the first end  71  of the fixation clip and the radially outer face  24  of the rim hook  22 . Since the centerline of the thread  73  intersects the second branch of the U of the fixation clip, the area of application D is shifted axially inward relative to said thread centerline, and so the fixation clip will duly roll around the rim hook and connecting piece, ensuring a very reliable fixation, since in order for the clip to leave its position, it has to increase its spread and so increase the clamping stress.  
         [0039]    [0039]FIG. 2 also shows that the bearing points between the connecting piece  6  and the radially inner face  23  of the rim hook  22  are preferably divided between at least two areas E and F arranged on either side of the hollow  25  of the rim hook  22 . In the example shown, the area F extends axially away from the inner side of the rim hollow  25 . This ensures a good fixation of the connecting piece  6  against the hook  22 , and the absence of any movement of the connecting piece  6 , and hence of the module  1 , which would tend to carry it towards and away from the rim seat  21  in service. In a preferred embodiment, the thickness of the plate is enough to prevent any appreciable amplitude of vibrations of the plate  5  in service. In a more preferred embodiment, the thickness of the plate  5  is 2 mm  
         [0040]    The module  1  ordinarily comprises an assembly of components such as pressure and temperature sensors, means of processing measurements of the sensors, means of transmitting these measurements to a receiver, such as a radio transmitter, located for example in the vehicle, and means of energy supply such as a battery or a cell. These components are well known to one skilled in the art. The assembly of these components is connected in a casing of small size and mass, preferably on the order of 80 g. The module  1  also comprises an outlet (not shown) for pneumatically connecting the pressure sensor to the inner hollow of the tire by way of a pneumatic connection such as an inflation valve (not shown).  
         [0041]    [0041]FIG. 5 shows a second embodiment of the fixation device  504 , according to the invention, for fixing a module  501  to a rim  502  of a standard sheet steel wheel  510  of a commercial vehicle. The wheel  510  is made up of a rim  502  and a disk  509 . The disk  509  and the rim  502  are assembled by welding in a transition area between the rim well and a hump  526  located at the axially inner end of the seat  521 . The device  504  comprises connecting means comprising a plate  505 , to which is fixed the module  501 , and a connecting piece  506 . The device  504  also comprises attachment means comprising a fixation clip  507  and a setscrew  508 .  
         [0042]    This embodiment is distinguished from the preceding embodiment in that the plate  505  is substantially L-shaped. Consequently, the two lugs  551  of the plate  505  are fixed to the axially outer part of the connecting piece  506  instead of the radially inner part as in the case of the plate  5 . This permits placing the module  501  directly under the hook  522  of the rim  502 . The module must be placed facing an opening  591  of the disk  509  to permit its emplacement.  
         [0043]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.