Abstract:
A tire structure including a secondary chamber formed between a tire casing and road engaging tire tread. A first air passage provided from the tire interior to the secondary chamber and a second air passage through a side wall of the tire casing substantially adjacent a bead portion of the tire. An air line extends between the two air passages and is bonded to the interior side wall of the casing, and a valve unit associated with said second passage to provide controlled air inlet and relief to said chamber.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a stud-bearing tire including mechanism for retracting and extending the studs, the mechanism being bonded to the tire during curing of the tire.  
       BACKGROUND OF INVENTION  
       [0002]     It is known that studs provided on tires provide increased traction when driving on snow and/or ice whereas they are non-beneficial and conversely detrimental to road maintenance when driving on bare roads (no ice or snow). Accordingly, systems have been developed for selective extension and retraction of the studs as illustrated by U.S. Pat. Nos. 6,244,666 and 6,386,252 as well as application U.S. Ser. No. 09/652,997, the disclosures of which are incorporated herein by reference.  
         [0003]     The extension and retraction process of the system herein contemplated utilizes air pressure that expands and contracts an air pocket or pockets that is independent of the primary air chamber of the tire. Providing an air source and mechanism for achieving the inflation and deflation of the air pocket is an objective of the present invention.  
       SUMMARY OF INVENTION  
       [0004]     A preferred embodiment of the present invention is (a) the provision of a circular channel in the outer side of the tire tread; (b) the provision of a circular strip of tread material as an inset into the circular channel, the strip provided with protruding studs as desired; (c) an air line or tube to be sealed against the inner wall of the tire and which provides an air conduit between the position of the tread channel and a designated position at the side wall of the tire; and (d) a miniaturized unit having selected features such as a self-charging battery, air pump, air pressure sensor/transmitter and valve stem. The above is incorporated into a tire through the process of (a) partial curing and thereby partial forming of a tire including an exterior circular channel; (b) providing an air passage (insertion of a metal ferrule) through the bottom of the tread channel and into the tire interior; (c) placement of the strip of tread material in the circular channel; (d) securing the air line to the inner wall of the tire which air line extends from the air passage to the designated position; (e) providing a second air passage through the tire wall at the designated position; (f) subjecting the tire and assembly of components to a final curing of the tire, the circular strip being adhered through said curing to the side walls of the tread chamber, and (g) snap on connection of the unit between the air line and second ferrule.  
         [0005]     The above combination and procedure results in the provision of a remote-controlled operation (as desired) whereby the miniature pump maintains a desired air pressure in the primary chamber of the tire; as desired, the valve of the mechanism is opened to convey air pressure from the primary chamber to the tread chamber formed under the strip which expands the strip out of the channel and into road contact; as desired, the valve of the mechanism is closed and the air from the tread chamber is conveyed back to the second passage and through the second passage to atmosphere. The invention will be more clearly understood and appreciated upon reference to the following detailed description and the drawings referred to therein. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0006]      FIG. 1  illustrates in perspective a tire including the present invention;  
         [0007]      FIG. 2  is a cross-sectional view of the tire of  FIG. 1  showing the studs in a retracted position;  
         [0008]      FIG. 3  is a further cross-section of the tire of  FIG. 1  showing the studs extended;  
         [0009]      FIGS. 4, 5  and  5 A illustrate the process of forming the tire of  FIG. 1 ; and  
         [0010]      FIGS. 6A and 6B  illustrate a tread strip insert of the invention. 
     
    
     DESCRIPTION  
       [0011]      FIG. 1  illustrates a tire  16  for a vehicle including a circular strip  10  centered in the tire tread  14 . The strip includes studs  12  as desired for enhanced gripping when traveling on ice or snow-laden roadways.  
         [0012]      FIGS. 2 and 3  illustrate the mechanism by which the strip  10  with studs  12  is expanded and contracted from and into a channel  18  formed in the tread  14 . A ferrule  20  from channel  18  (under strip  10 ) is projected through the tire casing where it is connected to an air line  22 . Air line  22  is adhered to the inner wall of the tire casing  38  and extends along the side wall to a position where at the air line is connected to a second ferrule  24  which provides air passage through the wall to atmosphere.  
         [0013]     Interposed between the ferrule  24  and air line  22  is a unit  26  that includes any of a variety of features such as a three way valve, self-charging battery, air pump and air pressure sensor/transmitter. Such devices are known and are commercially available, although not previously used in the capacity herein described.  
         [0014]     Operation of the full contingency of components of the unit  26  enables both automatic and remote control of the mechanism e.g. by remote control device  28  mounted in the vehicle cab and operated by the vehicle&#39;s driver. In such an operation, the unit  26  automatically senses air pressure in the primary chamber  30  and controls the operation of the air pump of the unit to maintain a desired air pressure in primary chamber  30 . When the driver encounters ice or snow, he will actuate the remote control device  28  which opens a valve of the unit  26  which in turn connects air line  22  to the primary air chamber  30 . Air is then conveyed to secondary chamber  32  ( FIG. 2 ) located under strip  10  to expand chamber  32  which extends strip  10  and stud  12  to the surface of tread  14  ( FIG. 3 ) and thus into engagement with a roadway on which the tire is driven (presumably covered with snow or ice).  
         [0015]     When the vehicle is no longer traveling in conditions of ice and or snow, the driver actuates the control device  28  to close the connection between chamber  30  and air line  22  and opens connection of the air line  22  to the passage through ferrule  24  and thereby to atmospheric pressure. The strip  10  at atmospheric pressure is retracted into the channel  18  as viewed in  FIG. 2  and such retracts studs  12  to out-of-engagement relation with the roadway.  
         [0016]     It will be observed that the illustrated structure includes a separate air inlet and valve  34  connected through tire rim  36  and into the primary air chamber  30 . However, it is contemplated that the ferrule  24  can be extended and designed to fit the air hoses of typical exterior air pumps and further designed whereby the valve of the device  26 , upon exposure to exterior air pressure through ferrule  24  will function to direct such exterior air pressure directly into the air chamber  30  and not to air line  22 .  
         [0017]     Having described the structure and the operation of the air-controlling mechanism, the following will describe the manner by which that mechanism is incorporated into a tire.  
         [0018]      FIGS. 4 and 5  illustrate a two-step curing operation. In  FIG. 4 , a first step has been performed to generate a basic tire structure including a tire casing  38 , a tread  14  secured to the casing  38  and channel  18  formed in the tread  14 . Subsequent to the first step of curing and prior to a second step of curing, a release strip  44  (in the form of an expandable tube in this preferred embodiment and which will be further described hereafter) is placed in the channel  18 . Ferrule  20  is forced through the casing  38  and into the channel  18  (under release strip  44 ). The second ferrule  24  is similarly applied to the casing wall and an air line  22  is placed at the inside of the casing between ferrules  20  and  24 . A circular tread strip  42  overlays release strip  44  in channel  18  and the composite is subjected to the second step of curing as represented in  FIG. 5 .  
         [0019]     Following the second cure process, the unit  26  is inserted between air line  22  and ferrule  24 . The unit  26  is designed in conjunction with the ferrule  24  and end  23  of air line  22  to be snap fitted into place (the unit  26  being anticipated to not withstand the heat of the curing operation).  
         [0020]     Further explanation of the release strip  44  and tread strip  42  is provided with reference to  FIGS. 6A, 6B . A tread segment  42  is pre-bonded/cured to a thin wall tube  44 , the tube  44  having a stem  46  that fits down through the ferrule  20  ( FIG. 4 ) for passage of air to and from the chamber  32 .  FIG. 6A  shows the tube  44  and tread strip  42  bonded together in a precuring operation and prior to bonding/curing thereof to the side walls of the tire channel  18 .  FIG. 6B  shows the tube  44  following the final curing step and in the expanded, stud extended position.  
         [0021]     It will be appreciated that there are numerous variations and modifications that can be made to the above disclosed embodiment without departing from the inventive concept as defined by the claims appended hereto. As previously explained, the unit  26  can be reduced to any or a combination of the features described i.e. self-charging battery, three way valve, air pump, air pressure sensor/transmitter. Conversely, in its simplest form, unit  26  can be eliminated and the air line  22  connected directly to ferrule  24 . Ferrule  24  would function as a conventional air inlet valve whereby air could be pumped to line  22  when extension of the studs is desired, and the valve manually depressed to release the air from line  22  to atmosphere for stud retraction. Alternatively the unit  26  could function merely as a remote controlled valve i.e. actuated to connect chambers  32  and  30  and actuated to close that connection and connect chamber  32  to atmosphere. (Numerous cycles of stud extension-retraction can be achieved with very gradual loss of air pressure in the primary chamber  30  of the tire.).