Patent Publication Number: US-2005126704-A1

Title: Method for attachment of tire pressure sensor

Description:
BACKGROUND  
      The present invention relates generally to adhesive bonding of one item to another item. More particularly, the present invention relates to a method for adhesive attachment of a tire pressure sensor.  
      In industries where a final product is assembled via the use of an assembly line, time is a precious commodity. Often, various portions of the final product need to be assembled in only a matter of seconds. Not only do these parts need to be attached to the final product quickly, but they also need to be attached securely, so that the part will not disengage from the rest of the product during the remainder of the assembly process or during use of the final product.  
      In the assembly of a vehicle, these concerns are even more critical. As the final product often travels at high rates of speed, a secure assembly is extremely important such that parts of the vehicle do not disengage during use. For example, a tire pressure sensor is often attached to the wheel or rim of a vehicle. An assembly line worker, on average, often has less than 10 seconds to attach such a sensor to each of the four or more wheels of the vehicle. Each of these sensors must be attached precisely, so that it will function properly in reading the tire pressure. Each sensor must also be attached securely, so that the sensor does not disengage from the tire due to assembly stresses or due to centripetal force during vehicle use. However, time constraints require that the sensors be attached very quickly so that the attachment operation does hot interfere with or delay other assembly operations.  
      Commonly, tire pressure sensors have been attached using a “snap on” system. A “snap on” system, such as that disclosed in U.S. Pat. No. 6,005,480 and incorporated by reference in the present application, uses a hole in the wheel rim to frictionally engage the tire pressure sensor with the vehicle wheel. However, for larger or heavier tire pressure sensors, this method is ineffective, as the tire sensor will disengage from the frictional attachment upon use of the vehicle at a high speed.  
      More commonly prevalent is a “clamp in” tire pressure sensor. A “clamp in” system, such as that disclosed in  FIGS. 2 and 3  of U.S. Pat. No. 5,600,301 and incorporated by reference in the present application, physically clamps the tire pressure sensor on to the wheel rim. While this method gives a more secure fit, a “clamp in” system is more expensive to implement due to the cost of additional assembly pieces and additional labor. Further, the “clamp in” method significantly slows down the assembly line process.  
      Adhesives have not been used in this process. Those adhesives that would be strong enough to keep a vehicle sensor attached to the tire throughout the assembly process and everyday use of the vehicle require a long cure time of at least about 6 to about 12 hours. Such adhesives require an assembly line worker or assembly line equipment to hold together the sensor and the surface to which it will be adhering for periods of at least about 10 to about 15 minutes. This slows and interferes with the overall vehicle assembly, which is not acceptable. Adhesives that would cure in the seconds that the assembly worker has to attach the tire sensor would not be strong enough to assure that the tire sensor will not disengage from the tire during assembly, let alone during use.  
     BRIEF SUMMARY  
      Accordingly, in one embodiment, there is provided a method for attaching a tire pressure sensor to a vehicle tire. An adhesive region is exposed on a tire pressure sensor. This adhesive region has first and second adhesive areas. The first adhesive area has a first adhesive with relatively short cure time. The second adhesive area has a second adhesive with a cure time longer than that of the first adhesive, and an adhesive strength greater than the adhesive strength of the first adhesive. The tire pressure sensor is then attached to said vehicle tire.  
      According to another embodiment, there is provided an adhesive system for a tire pressure sensor comprising an adhesion surface on the tire pressure sensor. The adhesion surface has an outer perimeter and an inner region. A first adhesive is located on the adhesion surface, the first adhesive having a relatively short cure time. A second adhesive is also located on the adhesion surface. The second adhesive has a relatively long cure time and an adhesive strength greater than that of said first adhesive.  
      According to yet another embodiment of the present invention, there is provided a tire sensor mountable to a wheel of a vehicle, the tire sensor comprising a housing including an adhesion surface. Adhesive material is disposed on the adhesion surface, the adhesive material including a first adhesive area having a relatively first curing adhesive and a second adhesive area having a relatively strong operating adhesive, the first adhesive area retaining the tire sensor during mounting on a mounting surface of the wheel while the second adhesive area cures to a relatively strong adhesive strength.  
      Other aspects of the present invention will become apparent in connection with the following description of the present invention. The foregoing discussion of the preferred embodiments has been provided only by way of introduction. Nothing in this section should be taken as a limitation on the following claims, which define the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a flow diagram of the method of the present invention;  
       FIG. 2A  is a view of an embodiment of an adhesive surface of the present invention;  
       FIG. 2B  is a view of an embodiment of the adhesive system of the present invention;  
       FIG. 3A  is a side view of an embodiment of the tire pressure sensor of the present invention; and  
       FIG. 3B  is a view of an embodiment of the tire pressure sensor of the present invention as attached to a vehicle wheel.  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED EMBODIMENTS  
      An assembly worker typically has a matter of seconds to attach a tire sensor to all tires or wheels on a vehicle. Preferably, an assembly worker has about 10 seconds or less to ensure that a tire sensor has been properly and permanently affixed to each wheel of a vehicle.  FIG. 3A  shows one embodiment of a tire pressure sensor  15  as disposed on a wheel  16  of a vehicle. The surface of the wheel  16  where it is contacted by the tire pressure sensor  15  is called an adhesion surface.  
       FIG. 2A  is a more detailed depiction of this surface. An adhesive surface  10  is chosen on a tire sensor as the point where adhesion is to occur. The adhesive surface  10  of  FIG. 2A  is depicted as a generally quadrilateral area, but may be of any shape necessary to promote adhesion of the tire sensor to the tire. Further, the adhesive surface  10  may encompass an entire side of the tire sensor, or may encompass only a portion of a side as necessary in the application. Adhesives are then placed on the adhesive regions of  FIG. 2A , resulting in the representative adhesive surface  10  of  FIG. 2B .  
      A first adhesive area  11  is composed of a first adhesive  12  with a relatively short cure time. Preferably, the cure time of the first adhesive  12  is less than about ten seconds; more preferably, the cure time of the first adhesive  12  is less than about five seconds. Any adhesive known in the art to have a short cure time may be used. For example, and without limitation, cyanoacrylates or isocyanates may be used as first adhesives  12 .  
      A second adhesive area  13  is composed of a second adhesive  14  with a relatively long cure time. The second adhesive  14  should have a cure time greater than that of the first adhesive  12 . Preferably, however, the second adhesive  14  should have a cure time of no more than about 12 hours; more preferably, the second adhesive should have a cure time of no more than about 6 hours. The second adhesive  14  should have a relatively high adhesion strength upon curing; preferably, the adhesion strength of the second adhesive  14  should be greater than about the adhesion strength of the first adhesive  12 . More preferably, the adhesion strength of the second adhesive  14  should be at least enough to solidly hold the tire pressure sensor to the wheel of the vehicle indefinitely at speeds of up to about 200 miles per hour. Further, the adhesive must have enough strength to overcome the centripetal force created by the rotational speed of the wheel and the mass of the tire pressure sensor device. Any adhesive known in the art to have a long cure time and a high adhesion strength may be used. For example, and without limitation, polyurethane or nitrile rubber based adhesives may be used as second adhesives  14 .  
      In the illustrated embodiment of  FIG. 2B , the first adhesive  12  is disposed around the second adhesive  14 , on the outer perimeter of adhesive surface  10 . The second adhesive  14  is preferably disposed on the inner region of the adhesive surface  10 . However, the first adhesive  12  and second adhesive  14  may be switched, or the first adhesive  12  only placed upon the corners or any other portion of the adhesive surface  10 , as is necessary to assure adhesion of the tire sensor to a tire. Preferably, the second adhesive  14  is placed on any region of the adhesive surface  10  not covered by the first adhesive  12 .  
       FIG. 1  is a flow diagram of one embodiment of the attachment method of the present disclosure. First, an adhesive surface is exposed at Box  100 . Preferably, the first adhesive  12  and second adhesive  14  are disposed on the adhesive surface  10  of the tire pressure sensor  15  prior to assembly, and remain covered or unexposed until an assembly worker is ready to assemble the tire pressure sensor to the tire.  FIG. 3A  shows one embodiment of a tire sensor  15 . The tire pressure sensor  15  includes a housing  18  containing a tire pressure sensing circuit, as is known in the art. The tire pressure sensor  15  has adhesives  12 ,  14  disposed on adhesive regions  11 ,  13  of the adhesive surface  10 , located on the housing  18  of the tire pressure sensor.  
      An adhesive backing  17 , as is known in the art and depicted in  FIG. 3A , may be used to cover the first adhesive  12  and second adhesive  14 , and protect the adhesives during shipping and storage. This adhesive backing  17  serves not only to keep the adhesive  12  and  14  contaminant-free until it is used, but also allows for the adhesive  12  and  14  to be disposed on the adhesive surface  10  in advance of use and in a uniform amount and thickness. By having the proper amount of adhesive ready for use upon removal of the adhesive backing  17 , the time required to perform this step of the method is reduced. In the particular embodiment of  FIG. 3A , a tire pressure sensor  15  is assembled with an adhesive  12  and  14  disposed on adhesive regions  11  and  13 , and an adhesive backing  17  disposed on the tire pressure sensor  15 . The tire pressure sensor  15 , along with other tire pressure sensors for a vehicle, is shipped to the vehicle assembly plant with the adhesive backing  17  in place. At the time of assembly of the tire sensor to the wheel rim, the adhesive backing  17  is peeled away, exposing both the first adhesive  12  and the second adhesive  14 .  
      The second step of the method, as illustrated at Box  110  in  FIG. 1 , is to attach the tire pressure sensor  15  to the vehicle wheel. A tire pressure sensor  15  as attached to a vehicle wheel  16  is depicted in  FIG. 3B . The short cure time of the first adhesive  12  allows it to make a secure connection with the vehicle wheel  16  in a very short amount of time. The first adhesive  12  is able to hold the fire pressure sensor  15  to the vehicle wheel  16  securely enough to allow the second adhesive  14  to be in contact with the vehicle wheel and to cure thereon. The first adhesive  12  therefore acts as the force to hold together the tire pressure sensor  15  and the vehicle wheel  16  while allowing the curing and bonding of the second adhesive  14  to the vehicle wheel  16 .  
      In the exemplary embodiment of  FIG. 3B , the tire pressure sensor  15  is attached to the vehicle wheel  16  itself. The adhesives  12 ,  14  are selected for use in conjunction with the metal wheel and may be specifically chosen for the particular metal (aluminum, steel, etc.) of the wheel. This is particularly useful in embodiments in which the tire pressure sensor and the valve stern are incorporated in the same unit, so that the tire pressure sensor  15  is attached to the wheel at a position in which the valve stem extends through a hole in the wheel. In other embodiments, the tire pressure sensor  15  is attached to the inside of the tire, such as on the side wall of the fire. In this embodiment, the adhesives  12 ,  14  are selected for attachment to the rubber tire or other material lining the tire at the attachment point.  
      Preferably, this method is performed on all tires of a vehicle, either simultaneously by a number of assembly line workers, or in rapid succession by a single assembly line worker. Preferably, the attachment method herein described can be accomplished on all wheels of a vehicle in less than about ten seconds.  
      The embodiments of the present invention disclosed allow for a secure, reliable, and simple method of attaching a tire pressure sensor to a vehicle wheel. Removing an adhesive backing and pressing the tire pressure sensor to the wheel wall is easier and more accurate than a snap-on or clamp-on system. Two regions of adhesive allow for a reasonably secure attachment of the tire pressure sensor to the vehicle wheel while the stronger, more secure adhesive cures. Such a method can easily be performed in an assembly line situation within the short period of time allowed for sensor attachment.  
      Although the invention herein has been described in connection with the embodiment of attaching tire pressure sensors to a vehicle wheel, it will be appreciated by those of skill in the art that the method and adhesive described herein may be used in other assembly line applications where an adhesive is to be used, without departing from the spirit and scope of the invention as defined in the appended claims.  
      Although the invention herein has been described in connection with a preferred embodiment thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions, and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.