Patent Publication Number: US-2005116531-A1

Title: Vehicle wheel comprising a fastening device for sensors

Description:
This is a Continuation-In-Part application of international application PCT/EP03/03815 filed Apr. 12, 2003 and claiming the priority of German application 102 24 444.8 filed Jun. 1, 2002. 
    
    
     BACKGROUND OF THE INVENTION  
      The invention relates to a vehicle wheel with a rim, a tire and a mounting device for a sensor for sensing conditions within the tire.  
      DE 196 26 446 A1 discloses a vehicle wheel with a tire and a sensor mounted on the vehicle wheel for detecting the tire air pressure. As mounting device, a clamping element is provided which can be attached to the rim in the well base thereof, for example, in a recess or opening so as to be connected to the rim in a force and form-locking manner.  
      It is the object of the present invention to provide an alternative mounting arrangement by which the fastening device can be attached to the wheel rim in a simple and reliable manner.  
     SUMMARY OF THE INVENTION  
      In a vehicle wheel with a rim for supporting a tire and a mounting device for a sensor for detecting at least one measurement value in the interior of the tire, the rim has a bore extending between the interior and an area ambient to the wheel into which the mounting device is inserted and in which it is sealingly retained.  
      The mounting arrangement is disposed in a space formed by the rim and the tire. This space will be called herein interior space. All other area around the rim and the tire will be called ambient area.  
      In accordance with the invention, a mounting area is provided in the interface area between the interior space and the ambient area. This mounting area is sealingly closed by the fastening device. The fastening device provides—in addition to the scaling—for a firm support for the sensor on the rim. The fastening device is for example connected to the rim by riveting or by bolting. By the accommodation of the fastening device in the mounting area, a particularly secure connection of the fastening device with the rim can be achieved. Since the connecting area between the rim and the fastening device is sealed, neither dirt nor moisture can enter the interior space of the rim, nor can pressurized tire air leak to the ambient area. The fastening device is firmly retained in the connecting area of the rim. A sensor can be mounted to the fastening device. Since the fastening device for the sensor is mounted to the rim independently of the sensor, the wheel comprising the rim, the tire and the fastening device can be operated with or without sensor.  
      In a particular embodiment of the invention, the fastening device is arranged in the well base of the rim. The well base is the radial recess in the center part of the rim. In the well base, the distance between the rim and the tire is maximal. In this way, a sensor mounted onto the fastening device is best protected from destruction during the mounting of the tire. The deep well base is the area of the rim with the smallest radius. This area is also closest to the wheel axis so that minimal centrifugal forces are generated by the fastening device and any sensor mounted thereto. Any static imbalance generated by the fastening device and the sensor attached thereto is therefore minimal. In addition, the deep well is axially centered in the rim. As a result, also, the dynamic imbalance generated by the fastening device and the sensor is minimal.  
      Preferably, the fastening device is provided with a contoured head. The contoured head is preferably spherical and therefore particularly suitable for mounting a sensor thereto in a variable orientation so that the sensor can be optimally positioned in the rim.  
      Further features and advantages of the invention will become apparent from the following description of a preferred embodiment thereof on the basis of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows part of a rim and a fastening device, and  
       FIG. 2  shows an enlarged section of the rim with the fastening device and a sensor mounted thereon. 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT  
       FIG. 1  shows in a sectional view an asymmetrical wheel rim  10  with a well base  11 . The rim includes at the transition to the well base  11 , an inclined area  12 . A tire  32  is mounted on the rim  11  defining an interior space  29 . At the side of the interior space  29 , the inclined area  12  is provided with a planar surface area  13  with a bore extending therethrough forming a passage  14 . The passage  14  interconnects the interior space  29  and the ambient area  30 . Further, a fastening device  15  is provided which includes a threaded bolt  16  with a contoured head  17 . The threaded bolt  16  form-fittingly insertable into the bore  14 . By screwing a nut  24  onto the bolt  16  a form-locking connection is established. The contour head  17  includes a planar base surface  20  with an annular groove  21  in which a seal ring  22  is disposed. The end of the contoured head remote from the threaded bolt  16  has a semi-spherical shape. At this end, the contoured head  19  includes an internally threaded blind end bore  18 , which is so arranged that it is axially aligned with the axis of the threaded bolt  16 .  
       FIG. 2  shows a rim  10  with the attachment device  15  and a sensor  26  mounted thereon. The threaded bolt  16  is inserted into the bore  14  from the interior space  29 . A unit  24  is threaded onto the threaded bolt  16  from the ambient area. By tightening the nut  24 , the attachment device  15  is connected to the rim under tension in a form-locking manner. However, the nut  24  can again be removed for removal of the attachment device  15 .  
      The arrangement of the seal ring  22  in the annular groove  21  of the contour head  17  of the attachment device  15  provides for the accurate positioning of the seal ring  22 , which is important for tight sealing. By tightening the nut  24 , the planar surface  20  of the attachment device  15  is pulled toward the planar surface  13  of the rim  10  while causing firm engagement of the seal ring  22  disposed in the groove  21  with the planar surface  13 . The interior space  29  of the vehicle wheel is therefore protected from moisture and dirt entering the bore  14  and also from loss of pressurized air from the interior space ( 29 ).  
      The threaded bore  18  in the contour head  17  of the attachment device  15  receives a mounting bolt  18  for mounting the sensor  26  to the attachment device  15 . In this way, the sensor  26  is properly positioned on the contour head  17  and attached to the vehicle wheel.  
      The sensor  26  has a contour contour area  27 , which is complementary to that of the contour head  17 . In the counter contour area, the sensor  26  is provided with an opening  28  for the reception of a mounting screw  25 . The opening  28  may be for example a bore or an elongated groove. The sensor  26  is placed with its counter contour area  27  onto the contour head  17 . The opening  28  in the sensor  26  is so arranged that it permits access to the threaded bore  18  in the contour head  17 . By means of the mounting screw  25 , the sensor  26  is mounted onto the contour head  17  of the attachment device  15 . In this way, the sensor cannot only be arranged in different discrete positions, but it may also be rotatable on the contour head  17  about the axis of the mounting screw  25 . The shape of the opening  28  in the sensor  26  facilitates the arrangement of the sensor  26  in various positions. If the opening  28  in the sensor  26  is larger than the diameter of the mounting bolt  18 , the sensor  26  can be moved laterally with respect to the mounting screw  25 . This connection also permits tilting of this sensor  26  about an axis normal to the axis of the bolt  18  before the nut  24  is tightened. The sensor  26  is therefore optimally adaptable to different rims  10  and the conditions provided thereby.  
      The sensor  26  is so oriented that it is optimally adapted to the shape of the particular rim  10 . In this optimum position, it is firmly mounted by tightening the nut  24 . Two attachment mechanisms may be utilized. With the first, the sensor is so mounted that the attachment device  15  is firmly connected to the sensor  26  by the mounting screw  25 . In this case, the contour  19  of the contour head  17  forms a supportive contact surface area. In another way, the sensor  26  may be so attached that the mounting screw  25  holds the sensor in firm engagement with the rim  10 . Where the rim  10  and the sensor  26  are in contact, the rim  10  supports the sensor  26 . In this case, the contour head  17  represents only a mounting an for holding the engagement screw  25 .  
      Instead of a semi-spherical head  17  another rotational symmetrical shape may be provided for the contour head  17  such as a truncated cone or a cylinder. Preferably, the sensor  26  is arranged opposite the valve  31  that is, displaced along the rim circumference by 180°. In this way, the imbalance provided by the sensor and the attachment device  15  is at least partially compensated for.