Abstract:
A process for producing a tire having an expandable chamber utilized for extending and retracting studs provided in the periphery of the tire. In one embodiment, a non-stick film is strategically positioned between the casing and the tread prior to curing the tread onto the casing. The interface at either side of the film forms the sides of an expandable chamber. The tread side of the chamber is inset and studs are affixed thereto. Expansion of the chamber extends the studs out of the inset and into engagement with a road surface. Alternative processes provide a channel in the tread and the expansion chamber formed in the channel.

Description:
This is a continuation-in-part of U.S. application Ser. No. 09/284,557 filed on Apr. 14, 1999, which was the National Stage of International Application No. PCT/US97/19454, filed Oct. 17, 1997, now U.S. Pat. No. 6,386,252; which is a continuation-in-part of U.S. application Ser. No. 08/909,302 filed on Aug. 11, 1997, now U.S. Pat. No. 5,810,451; which is a continuation-in-part of U.S. application Ser. No. 08/733,676 filed on Oct. 17, 1996, now U.S. Pat. No. 5,788,335. 

   FIELD OF THE INVENTION 
   This invention relates to a process for creating a secondary expandable chamber cooperatively arranged with an extendable portion of the tire tread to provide the means to induce independent engagement and disengagement of that portion with a road surface. 
   BACKGROUND OF THE INVENTION 
   This invention is a further development to the commonly owned inventions of U.S. Pat. Nos. 5,788,335 and 5,810,451, the disclosures of which are incorporated herein by reference. 
   Whereas the concept has been developed wherein a tire is provided with an efficient way to extend and retract a tread portion, e.g., carrying studs, the present invention is directed to a process for the efficient incorporation of that concept to state of the art vehicle tires. 
   Tires have undergone impressive development over the years. Fifty years ago a tire wasn&#39;t expected to last for much more than 10,000 miles of driving. Even then blow outs were common occurrences and such were considered a major hazard of driving. Today a blow out is almost unheard of and a set of tires can last in excess of 80,000 miles. 
   Reference is made to  FIG. 1  which illustrates the structure of a state of the art tire. The tire consists of two parts which are referred to as the casing  10  and the tread  12 . The casing is a continuous wall from a first bead  14  to an opposite bead  16  at the respective sides of the casing. The beads fit the tire rim (not shown) which closes off the inner opening  18 . The casing is a composite of steel fibers and tough rubber and will withstand very substantial abuse. 
   The casing material is hard and will not adequately grip a roadway as necessary to achieve traction. That is the job of the tread  12 . The tread is a relatively soft rubber that provides the desired grip. The tread is adhered to the casing by a molding process. The uncured rubber is laid inside a mold that is shaped to form the desired tread design. The casing is abutted against the uncured rubber and the molding apparatus applies pressure and heat to cure the rubber  12  and bond it securely to the casing. With the tire removed from the mold, the tread design has been permanently molded into the exterior face  20 . 
   BRIEF DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
   The invention provides for the formation of a secondary air chamber (the first chamber occupying the space  21  inside the casing  10 ). This secondary chamber is preferably formed at the interface between the casing and the tread. Studs may be imbedded in the portion of the tread that overlies the secondary air chamber and the tread thickness of that portion is reduced and inset into the tire tread so that the studs do not extend to the tread periphery. They are preferably inset to an extent that they do not extend to the tread periphery until 60 percent of the usable tread thickness is worn away. 
   The formation of the reduced thickness of the tread is formed by configuring the mold form to form an indentation in the tread face during the molding process. The secondary air chamber is formed by placing a non-adhering material such as tape, powder, liquid, e.g., in the form of a Teflon™ tape on the casing surface and surrounding the casing. When the tread rubber is bonded to the casing in the molding process, the portion of the casing and the rubber tread at either side of the Teflon™ tape are not bonded to either the tape or each other and thus provide a separation that forms the chamber. The reduced thickness of tread overlies the tape and thus the secondary chamber. 
   Air pumped into the chamber extends the tread overlying the chamber outwardly to the tread periphery. Studs can be imbedded in the reduced thickness tread and an air valve extended into the secondary chamber to controllably expand and contract the chamber. (The resiliency of the rubber induces retraction when the air pressure to the chamber is depleted.) Alternately the extendable tread in a non-extended state may be non-studded and function as a water trough on wet roads and extended for greater surface gripping on dry roads. 
   Whereas the above is a preferred design, the procedure can be accomplished by first forming an indentation whereby the bottom of the indentation forms the inside wall of the chamber. A Teflon™ tape can be laid in the indentation and a secondary tread forming process applied to bond a strip of rubber to the walls of the indentation overlying the Teflon™ strip. 
   A process can also be used which provides for a tube to be laid in the indentation and the secondary rubber layer bonded over the tube. The tube can also be suitable as the center tread portion having studs imbedded in the tube. The elasticity of the tube assures secure gripping of the tube to the tread at the indentations. This eliminates the secondary molding process. 
   Each of the above processes has benefits and disadvantages which will become apparent upon reference to the following detailed description having reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of a state of the art tire to which the invention is applied; 
       FIG. 2  is an illustration of a casing such as used in the tire of  FIG. 1 ; 
       FIG. 3  is a schematic illustration of an uncured rubber section such as used to form a tire tread on the casing of  FIG. 2 ; 
       FIG. 4  is a schematic illustration of a strip of non-adhesive film or strip such as Teflon™ tape; 
       FIG. 5  is a schematic illustration of a molding process for molding the components of  FIGS. 2-4  into a tire in accordance with the present invention; 
       FIG. 6  is a schematic illustration of the step of inserting studs into a tire formed in the molding process of  FIG. 5 ; 
       FIG. 7  is a schematic illustration of a tire produced from the process of  FIGS. 5 and 6  in accordance with the present invention; 
       FIG. 8  is a schematic illustration of an alternative molding process including a first step thereof; 
       FIG. 9  is an illustration of a second step in the alternative process of  FIG. 8 ; 
       FIG. 10  is an illustration of a third step in the alternative process of  FIGS. 8 and 9 ; 
       FIGS. 11A and 11B  are illustrations of a deflated and inflated collapsible tube to be used in a second alternative process; 
       FIG. 12  is an illustration of a deflated, collapsible, inflatable tube to be used in a third alternative process; 
       FIG. 13  is a schematic illustration of a tire produced with the collapsible/inflatable tube of  FIG. 12 ; and 
       FIGS. 14-16  illustrate an example for providing expansion and contraction of the air chamber created by the process of the invention. 
       FIGS. 17-19  illustrate further examples of mechanisms for expansion and contraction of the air chamber. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIGS. 1-7 , illustrated in  FIG. 1  is a state of the art tire having a steel reinforced casing  10  on which is bonded, by curing, a tire tread  12 . The casing  10  and uncured tread rubber segment  12 ′ are illustrated in  FIGS. 2 and 3 .  FIG. 4  illustrates a non-adhering adhesive strip, e.g., Teflon™ tape  14  which is used in the illustrated process of  FIGS. 1-7 . 
   The process is substantially illustrated in FIG.  5 . The mold form  16  is modified by the inclusion of an indentation forming boss  18 . The strip  14  is positioned around the casing periphery as indicated by dash lines in FIG.  2  and the uncured rubber segment  12 ′ is placed on the casing, e.g., by extrusion. The casing  10 , strips  14  and uncured rubber segment  12 ′ are then inserted into the mold form  16  as illustrated in  FIG. 5. A  plunger portion  18  of the molding apparatus is then inserted into the mold form behind the casing  10  and suitable heat and pressure (indicated by arrows) are applied to cause a curing of the tread rubber  12 ′ and thereby a bonding of the cured tread rubber  12  to the casing  10  except at the interface wherein resides the strip  14 . Neither the rubber or the casing is bonded to the strip (although should it bond to one or the other, the invention would not be affected and it may even be desirable to provide bonding of the strip to the casing prior to the curing process to insure that the strip is maintained in place). It may be desirable that the rubber segment over the strip  14  have a different foundation, i.e., diameter which is readily provided in the extrusion process. 
   Following removal of the tire from the mold form, studs are inserted (if desired) in the reduced section of the tread (over the chamber  23 ) and a valve and line  24  are inserted into the chamber  23  (See FIG.  6 ). Although shown to be inserted from the inside, i.e., through chamber  18 , it is contemplated that an alternative valve and line  24 ′ could be inserted from the side of the tread, e.g., external of the chamber  18  as illustrated in dash lines in FIG.  6 .  FIG. 7  illustrates the completed tire of the invention. 
     FIGS. 8-10  illustrate a first alternative embodiment of the invention. In  FIG. 8 , an indentation is formed into the uncured tread tire segment  12  by boss  28  of mold form  26  that is likely deeper than illustrated for FIG.  5 . This forms a tire  30  having indentation  31  as shown in FIG.  9 . The strip  14  of  FIG. 4  is placed in the indentation  31  and as illustrated in  FIG. 10 , a further molding process is initiated whereby an uncured tread rubber segment  32  is placed over the strip  14  and a following cure step cures and bonds the rubber  32  to the case  10  of tire  30  to again form the collapsible chamber similar to that of  FIG. 7  but within the tire tread and not at the interface of the tire tread and casing. 
     FIGS. 11A and 11B  illustrate an inflatable tube  34  in a deflated state and inflated state, respectively. Such a tube can replace the strip  14  in the process of either  FIG. 5  or  10 . 
     FIGS. 12 and 13  illustrate a further variation.  FIG. 12  illustrates a tube  36  that is sufficiently tough to carry studs  22  and withstand direct exposure to the roadway. With reference to  FIG. 9 , the strip  14  can be replaced by tube  36 . It is a full circular tube and is seated in the indentation  31  of the tire tread. It may be desirable to provide lobes  38  for the tube and lobe forms for the tire tread at the sides of the indentation  31 . Such would prevent the tubes from sliding around the tire. A valve and line such as illustrated in dash lines at  24 ′ in  FIG. 6  may be preferable for this alternative tire. Also, it will be appreciated that the tube may preferably be constructed to have highly resistive elasticity for securing the tube in the indentation. 
   With reference to  FIG. 7 , it will be appreciated that the air input  24  can be provided from an external source. However, for the preferred embodiment it has been established that a most convenient source for the air pressure for the chamber  23  is from the air pressure available from the main tire chamber  21 . The air consumed by filling the chamber  23  is negligible as compared to the air source of the main tire chamber. Thus, a valve system that expands chamber  23  from air pressure in tire chamber  21  and exhausts the air from chamber  23  to atmosphere will allow for dozens of cycles with no noticeable affect on the tire inflation. Such a valving system is illustrated in  FIGS. 14-16 . 
     FIG. 14  is similar to FIG.  7  and illustrates air transfer line  24  and valve stem  44  extending from chamber  23  and through a wheel rim  46 . (See  FIG. 15 ) In  FIG. 15 , valve stem  48  is the main tire valve stem and  50  indicates a wheel hub. 
     FIG. 16  illustrates stem  44  connected by air transfer hose  52  to main tire valve stem  48 . When the two chambers are connected in such manner, air pressure is equalized between the two chambers and expansion of chamber  23  is accomplished. When the air transfer hose is disconnected from valve stem  44 , the air pressure in chamber  23  is exhausted to atmosphere through valve stem  44  due to the memory of the chamber and the chamber returns to its non-expanded condition. In the alternative, the air hose  52  can be regulated to allow only a portion of the main tire pressure to move into expandable chamber  23 , should main tire air pressure be greater than needed to expand expandable chamber  23 . A variety of methods to connect the two chambers for the purpose of expanding chamber  23  can be constructed, the air transfer hose being the simplest to illustrate. 
     FIG. 17  illustrates the insertion of a pump  54  connected to the air transfer system (in this case connected to hose  52 ). The pump can be used (1) to help extract additional air pressure from the tire chamber (or an alternative bellows chamber used for the storing of air) if needed by the expandable chamber  23 , (2) assist in equalization of tire chamber pressure and expandable chamber pressure and (3) extraction of air from the expandable chamber back to the tire or alternative bellows storage unit. This pump allows for the air system to be self-contained without the need to exhaust the air to atmosphere or import air from some exterior tank or other source to inflate either the tire chamber or the expandable chamber. 
     FIG. 18 , in the alternative, illustrates a mechanical bellows  56  capable of holding enough air to fully expand the expandable chamber  23  for expansion and remove the air for deflation, without need of using the air pressure contained within the main tire. This system also allows for the air system to be self-contained without the need to exhaust air to atmosphere or import air from some exterior tank, the tire chamber or other source. The bellows can be mounted in an interior position within the tire chamber and on top of the wheel rim  46  as illustrated where the bellows  56  is strapped around the wheel rim  46  with an adjustment  58  making installation on any size wheel possible. A power supply battery pack  60  is mounted opposite the bellows  56  to balance the wheel. 
   Illustrated in dash lines in  FIG. 18  is an exterior valve and tube  62  installed to allow import of exterior air. The bellows  56  can then be used as an air pump to supply air pressure to the tire chamber through exhausting pressurized air from bellows  56 . In this iteration a second valve equipped with a venturi filter is placed within the bellows  56  to selectively allow for pressure to be transferred to tire chamber  21  or to expandable chamber  23 . 
     FIG. 19  illustrates an alternative method by which valve stem tube  24 ′ does not pass through the tire casing but is implanted within the tire tread and the outer rubber on the casing wall and exits exteriorly from the side wall prior to the bead segment of the casing. In the alternative, the valve stem  44  exits into the main tire chamber (shown in dash line). 
   A further variation is the color coding of the tread  12 . As indicated by cross hatching in  FIG. 7 , the tread may be colored one color, e.g., green, (cross hatching  40 ) to indicate acceptable remaining wear life. When approaching the 60 degree wear life whereat the non-extended studs will be exposed, the color orange or yellow, indicated by cross hatching  42 , will start showing at the tread surface. A third color, e.g., red, could indicate that the wear life has been expended. 
   The above are but a few variations of the invention herein contemplated and those skilled in the art will appreciate the numerous modifications and variations that are possible and such modifications and variations are encompassed by the invention as claimed in the appended claims.