Abstract:
An air maintenance tire assembly includes an air pumping passageway located within a tire sidewall to generate compressed air. An outlet screw assembly includes an elongate screw body residing within a profiled sidewall bore. The screw body extends through an axial span of the first sidewall to the tire cavity to conduct air from the sidewall air passageway to the tire cavity. The screw body has enlarged sectional end components to deter radial dislodging of the screw body from the sidewall bore during operation.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to air maintenance tires and, more specifically, to such tires having an air pumping sidewall passageway and an outlet air passage assembly for conducting compressed air from the sidewall passageway into a tire cavity. 
       BACKGROUND OF THE INVENTION 
       [0002]    Normal air diffusion reduces tire pressure over time. The natural state of tires is under inflated. Accordingly, drivers must repeatedly act to maintain tire pressures or they will see reduced fuel economy, tire life and reduced vehicle braking and handling performance. Tire pressure monitoring systems have been proposed to warn drivers when tire pressure is significantly low. Such systems, however, remain dependent upon the driver taking remedial action when warned to re-inflate a tire to recommended pressure. It is a desirable, therefore, to incorporate an air maintenance pumping system within a tire that will maintain tire air pressure to compensate for any reduction in tire pressure over time without the need for driver intervention. 
         [0003]    Such air maintenance pumping systems require an outlet assembly for conducting compressed air from the pumping mechanism into a tire cavity. It is desirable, therefore, to incorporate an outlet assembly for such purpose into the air maintenance tire assembly that is secure, reliable and readily repaired in the event that repair becomes necessary. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect of the invention, an air maintenance tire assembly includes an air pumping passageway located within a tire sidewall to generate compressed air. An inlet air passage screw assembly is inserted into a sidewall bore and through the tire sidewall to the tire cavity and conducts air from outside the tire to a regulator positioned within the tire cavity. An outlet screw assembly includes an elongate screw body residing within a profiled sidewall bore. The screw body extends through an axial span of the first sidewall to the tire cavity to conduct air from the sidewall air passageway to the tire cavity. The screw body has a T-block insert from which one or more projecting arm(s) extend, the projecting arm fitting within a sidewall air pumping passageway to conduct compressed air from the sidewall air passageway to a screw body internal air pathway. 
         [0005]    In another aspect, the T-block insert seats within a receptacle body connected to a radially outward end of the screw body, the receptacle body having a relatively large cross-sectional dimension to inhibit the screw body pulling through the tire sidewall during operation. 
         [0006]    According to a further aspect, the assembly includes a valve housing at a radially inward end of the screw body residing within the tire cavity. A valve mechanism seats within the valve socket, the valve mechanism opening to conduct air from the internal air pathway of the screw body into the tire cavity and closing to prevent a backflow of air from the tire cavity into the internal air pathway of the screw body. 
         [0007]    The valve housing has, in an additional aspect of the invention, an outwardly projecting peripheral flange abutting the tire inner liner, peripheral flange to deter a radially outward pull out of the screw body from the sidewall bore. 
       DESCRIPTION 
       [0008]    “Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100 percent for expression as a percentage. 
         [0009]    “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
         [0010]    “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
         [0011]    “Chafer” is a narrow strip of material placed around the outside of a tire bead to protect the cord plies from wearing and cutting against the rim and distribute the flexing above the rim. 
         [0012]    “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
         [0013]    “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
         [0014]    “Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure. 
         [0015]    “Groove” means an elongated void area in a tread that may extend circumferentially or laterally about the tread in a straight, curved, or zigzag manner. Circumferentially and laterally extending grooves sometimes have common portions. The “groove width” is equal to tread surface area occupied by a groove or groove portion, the width of which is in question, divided by the length of such groove or groove portion; thus, the groove width is its average width over its length. Grooves may be of varying depths in a tire. The depth of a groove may vary around the circumference of the tread, or the depth of one groove may be constant but vary from the depth of another groove in the tire. If such narrow or wide grooves are substantially reduced depth as compared to wide circumferential grooves which the interconnect, they are regarded as forming “tie bars” tending to maintain a rib-like character in tread region involved. 
         [0016]    “Inboard side” means the side of the tire nearest the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle. 
         [0017]    “Lateral” means an axial direction. 
         [0018]    “Lateral edges” means a line tangent to the axially outermost tread contact patch or footprint as measured under normal load and tire inflation, the lines being parallel to the equatorial centerplane. 
         [0019]    “Net contact area” means the total area of ground contacting tread elements between the lateral edges around the entire circumference of the tread divided by the gross area of the entire tread between the lateral edges. 
         [0020]    “Non-directional tread” means a tread that has no preferred direction of forward travel and is not required to be positioned on a vehicle in a specific wheel position or positions to ensure that the tread pattern is aligned with the preferred direction of travel. Conversely, a directional tread pattern has a preferred direction of travel requiring specific wheel positioning. 
         [0021]    “Outboard side” means the side of the tire farthest away from the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle. 
         [0022]    “Peristaltic” means operating by means of wave-like contractions that propel contained matter, such as air, along tubular pathways. 
         [0023]    “Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire. 
         [0024]    “Rib” means a circumferentially extending strip of rubber on the tread which is defined by at least one circumferential groove and either a second such groove or a lateral edge, the strip being laterally undivided by full-depth grooves. 
         [0025]    “Sipe” means small slots molded into the tread elements of the tire that subdivide the tread surface and improve traction, sipes are generally narrow in width and close in the tires footprint as opposed to grooves that remain open in the tire&#39;s footprint. 
         [0026]    “Tread element” or “traction element” means a rib or a block element defined by having a shape adjacent grooves. 
         [0027]    “Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention will be described by way of example and with reference to the accompanying drawings in which: 
           [0029]      FIG. 1  is a perspective view of a tire with pump channels using the inlet air passageway screw assembly with regulator and bi-directional outlet screw assembly. 
           [0030]      FIG. 2  is a side view of the tire with pump channels using the inlet air passage screw assembly with regulator and outlet screw assembly. Tire rotation is counter-clockwise and air flow is clockwise. 
           [0031]      FIG. 3  is a side view of the a tire with pump channels using the inlet air passageway screw assembly with regulator and bi-directional outlet screw assembly. Tire rotation is clockwise and air flow is counter-clockwise, showing the bi-directionality of the air maintenance system. 
           [0032]      FIG. 4  is a partially sectioned perspective view showing the air passage inlet screw assembly with a regulator exploded. 
           [0033]      FIG. 5  is a partially sectioned section perspective view showing the air passage inlet screw assembly with a regulator exploded. 
           [0034]      FIG. 6  is a perspective view of the air passage inlet screw assembly. 
           [0035]      FIG. 7  is a section view of the inlet taken from  FIG. 6 . 
           [0036]      FIG. 8  is an exploded perspective view of the inlet assembly. 
           [0037]      FIG. 9A  is a section view taken from  FIG. 5  showing air passing through the filter and entering the duck valve. 
           [0038]      FIG. 9B  is a section view showing air passing through the duck valve and entering a pump channel enroute to the outlet. 
           [0039]      FIG. 10  is a partially sectioned perspective view showing the bi-directional outlet screw assembly exploded. 
           [0040]      FIG. 11  is a partially sectioned perspective view showing the bi-directional outlet screw assembly installed. 
           [0041]      FIG. 12  is a perspective view of the bi-directional outlet screw assembly. 
           [0042]      FIG. 13  is a section view of the outlet screw assembly taken from  FIG. 12 . 
           [0043]      FIG. 14  is an exploded perspective view of the bi-directional outlet screw assembly. 
           [0044]      FIG. 15A  is a section view taken from  FIG. 11  showing air coming from the pump channel, entering the outlet and entering the duck valve. 
           [0045]      FIG. 15B  is a section view showing air passing through the duck valve and entering the tire cavity. 
           [0046]      FIG. 16  is a side view of the tire with pump channels using an air passage screw inlet with a regulator and a mono-directional outlet screw. Tire rotation is counter-clockwise and air flow is clockwise. 
           [0047]      FIG. 17  is a perspective view of the mono-directional outlet screw assembly. 
           [0048]      FIG. 18  is a section view of the mono-directional outlet taken from  FIG. 17 . 
           [0049]      FIG. 19  is an exploded perspective view of the mono-directional outlet screw assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0050]    Referring to  FIGS. 1 through 5 , a tire assembly  10  includes a tire  12 , and a tire-based peristaltic pump assembly  14 . The tire  12  mounts in conventional fashion to a rim  13  for vehicle use. The tire is of conventional construction, having a pair of sidewalls  16 ,  18  extending from opposite bead areas  20 ,  22  to a crown or tire read region  24 . The tire and rim enclose a tire cavity  28  that is defined by a tire inner liner  26 . 
         [0051]    As seen from  FIGS. 1 through 5 , the peristaltic pump assembly  14  includes an annular air passageway  19  formed within one of the tire sidewalls  16 ,  18 . Alternatively, a pump assembly  14  may be placed in both sidewalls if desired. The passageway  19  is enclosed by its host sidewall and may extend  360  degrees about the circumference of the sidewall for bi-directional capability or, alternatively,  180  degrees for mono-directional capability. The air passageway is surrounded by resilient sidewall material such that the passageway  19  may be placed segment by segment into a flattened condition subject to external force and, upon removal of such force, returns to an original condition generally circular in cross-section. The passageway  19  has a diameter sufficient to operatively push a volume of air sufficient for the purposes described herein. Air “passageway”  19  is also referred to herein as an air “channel”. The passageway or channel  19  is enclosed within a tire sidewall and functions to provide an air pumping device for pressurizing internal air flow around the passageway  19  as the tire rotates against a ground surface. 
         [0052]    The operational principle of the peristaltic pumping tube in a tire for the purpose of maintaining tire air pressure is described in issued U.S. Pat. No. 8,113,254, hereby incorporated herein by reference in its entirety. As disclosed, a peristaltic pumping tube is incorporate within a tire sidewall. As disclosed by the above patent incorporated by reference herein, a T-shaped inlet device is affixed inline with an annular pumping tube and conducts air from outside of the tire into the pumping tube for pressurization. A T-shaped outlet device, positioned opposite the inlet device, is likewise affixed inline with the pumping tube. The outlet device conducts pressurized air from the pumping tube into the tire cavity to maintain cavity pressure at a desired level. Functionally, the pumping tube is located in a high flex region of the sidewall. So located, the pumping tube compresses segment by segment from an expanded diameter to a substantially reduced diameter responsive to a bending strain introduced into the sidewall from a rolling tire footprint. Pressurized air is thereby forced segment by segment along the air tube and directed as needed into the tire cavity for pressure maintenance. 
         [0053]    The subject invention pump works pursuant to the same principle as the patent but uses an integral air passageway formed within and by the tire sidewall instead of a separate tube placed inside a sidewall groove. 
         [0054]    While working well, the inlet and outlet devices taught by U.S. Pat. No. 8,113,254 are relatively large and their incorporation into and occupancy within a tire sidewall introduces structural disruption in the sidewall. Moreover, the inlet and outlet devices are difficult to access and repair should that become necessary. Finally, the inlet and outlet devices of the patent are not easily affixed to the air tube and replacing such devices within a tire sidewall could prove problematic. 
         [0055]    The peristaltic pump assembly  14  of the subject invention provides an inlet air passageway screw assembly and an outlet air passageway assembly. Such assemblies are alternatively referred to herein as “inlet screw assembly” and “outlet screw assembly” from a preferred assembly of such assemblies through a tire sidewall bore by twisting or screwing. Air from outside the tire is routed by the inlet air passageway assembly  36  to a regulator  30  mounted to the tire inner liner  26 . The regulator  30  is of a type commercially available and includes a pressure monitoring sensor that measures air pressure within the tire cavity  28 . The regulator  30  opens when air pressure within the cavity  28  falls below a threshold level and allows air from the inlet assembly  36  to pass through regulator outlet conduits  32 ,  34  to the air passageway  19  If air pressure within the cavity  28  is at or above the threshold, air to the pumping passageway  19  is blocked. A suitable representative regulator manufacturer is Eaton Corporation and a suitable regulator configuration is as shown and described in PCT Patent Application No. PCT-US2015/010441, filed on Jan. 15, 2015, and entitled SELF-INFLATING TIRE AIR REGULATOR, hereby incorporated herein in its entirety. 
         [0056]    An outlet screw assembly  74  mounts to the tire at a location opposite the inlet air passageway assembly  36  as seen in  FIGS. 1 through 3 . The outlet screw assembly  74  directs pressurized air from the air passageway  19  into the tire cavity  28 . Air is forced segment-by-segment along the air passageway  19  from pressure on the air passageway is exerted from rotation of the tire against a road surface. In  FIG. 2 , it is shown that a counter clockwise rotation of the tire against a road surface forces air in a clockwise direction along the air passageway  19 . Air along the passageway  19  is thus pressurized and forced through the outlet assembly  74  and into the tire cavity. In  FIG. 3 , bi-directionality of the 360 degree air passageway is demonstrated as the tire rotates in a clockwise direction, forcing air along the passageway in a counter-clockwise direction. 
         [0057]    Referring to  FIGS. 4 through 8 , the inlet air passageway assembly  36  and its assembly into the tire sidewall  16  is shown in detail. The air passageway assembly  36  is referred to herein as an “air passageway screw assembly” or an “air passageway screw” due to the torque applied to the assembly during its insertion through a tire sidewall. The regulator  30  has a housing mounted against the tire inner liner  26 . The regulator  30  provides an internally threaded socket  31  positioned between the conduits  32 ,  34 . The inlet air passageway assembly  36  is shown in detail by  FIGS. 6 through 8 . A porous or cellular air filter  38  in the form of a cylindrical body is used to clean air drawn into the system from outside the tire. An elongate generally cylindrical, dumbbell-shaped screw body  48  is preferably of a unitary construction. The body  48  may be formed from a suitable rigid material such as plastic resin. The screw body  48  includes a cylindrical, relatively large-diameter, filter housing  44 , a relatively small-diameter tubular midsection portion  46  also referred herein as a “shank” portion, and a mid-sized large-diameter cylindrical valve housing  48 . The filter housing  44  is bowl-shaped and receives therein the filter  38 . Internal threads at  58  of the housing  44  engage external threads  56  of a cap  40 . The cap  40  threads into the housing  42  to enclose the filter  38 . The cap  40  has an access opening  41  allowing air to pass into the housing  42  from outside the tire. Such inlet air passes through and is cleansed by the filter  38 . 
         [0058]    The screw body  48  forms an axial air pathway  54  through the body as shown. A check valve  50  is provided in the preferred form of a duck bill valve but other valve configurations may be used if desired. The valve  50  has a peripheral annular retaining flange  60  and is sized for receipt into a valve socket  63  positioned at a lower end of valve housing  48 . The flange  60  of the valve  50  seats in a supported fashion within the housing socket as shown in  FIG. 7 . The retainer ring  52  is cylindrical and externally threaded to engage internal screw threads within the valve housing socket  63 . Once inserted, the retainer ring  52  abuts against the valve flange  60  to retain the valve  50  in a seated position within the socket  63  of the housing  48 . 
         [0059]    The assembled inlet air passageway assembly  36  is shown  FIGS. 4, 6 and 7 . The assembly  36  inserts and attaches to the tire sidewall  16  by means of screw insertion of the assembly  36  through a profiled bore  64  extending through the sidewall as shown. The profiled bore  64  includes a larger diameter filter housing-receiving bore portion  66  and a tubular inner bore shank segment  68  sized nominally larger in section than the screw body shank  46  of the inlet air passageway assembly  36 . The inner bore segment  68  is diametrically sized larger than the screw body shank  46  to allow the valve housing at the terminal inward end of the screw body shank to be screwed through the bore during assembly of the assembly  36  through the sidewall. The assembly  36  is inserted into the bore  64  in a post-cure procedure. Once assembled through the bore  64 , the valve housing  48  by means of external screw threads  62  threads into the socket  31  of the regulator  30 . The regulator is thus securely coupled to the inlet air passageway assembly  36  and, in particular, the screw body  48 . The air pathway  54  extending through the assembly  36  is thus placed in air flow communication with the regulator  30 . Air intake from outside of the tire passes through the filter  38 , the air pathway  54 , and the duck valve  50  to enter into the regulator  30 . 
         [0060]      FIG. 9A  illustrates by arrows  70  the air flow path in the closed position with duck valve  50  closed or shut. The valve closes by membrane constriction when air is not drawn through the valve from outside the tire. The regulator shuts off air flow into the tire whenever the air pressure within the tire is at or above the desired pressure level. Air intake into the and through the regulator from the inlet air passageway assembly  36  is blocked and the duck valve  50  remains in a closed position until air flow through the regulator starts. When air pressure is low in the tire, the regulator opens and allows intake air to pass through the regulator conduits  32 ,  34 . In  FIG. 9B , the valve  50  is shown in the open condition, allowing air flow (arrows  72 ) to pass through the filter  38 , along the air pathway  54 , through the duck valve  50 , and into the regulator  30 . The open condition is controlled by the regulator which opens whenever the air pressure within the tire, as sensed by the regulator pressure sensor, falls below a desired level. The regulator  30  allows air to pass into either outlet conduit  32  or outlet conduit  34 , depending on the direction of tire rotation. Air from conduit  32  or  34  is introduced into the annular groove within the tire sidewall forming the tire air passageway  19 . Rotation of the tire forces the air along the groove  19  toward an outlet assembly and through the outlet assembly into the tire cavity. Air pressure within the tire cavity is thereby raised to the desired level. 
         [0061]    It will be seen from  FIGS. 4 through 9B  that the air passageway assembly  36  is in the form of a screw that is twisted through the sidewall bore during sidewall attachment and then subsequently screws into the regulator  30 . The peristaltic pump assembly  14  requires an air passage from the surrounding atmospheric air through the tire sidewall in order to replace the lost air from the tire. The air passageway assembly or screw  36  provides a filter to allow clean air to enter the AMT system, and to the tire. Furthermore, the system incorporates additional functionality in housing an air filter, mounting the regulator to the tire. The check valve  82  incorporated within the air passageway assembly  36  operates as a guard against back flow of air from the AMT system to the atmosphere surrounding the tire. The valve  82  allows air to flow into the tire but prevents back flow of air from the tire. 
         [0062]    The screw assembly body  42  is pushed and twisted from outside of the tire through the molded bore (hole)  64 . The shape of the bore  64  matches the air passage screw assembly shape. Once through the tire sidewall and in position, the valve  50  and housing  52  are installed into the housing  48 , and the screw assembly is then screwed into the regulator  30 . Lastly, the filter  38  is enclosed within housing  42  by the cap  40 . The dumbbell general shape of the screw assembly prevents its detachment from the tire sidewall bore in either inward or outward directions. The filter housing  44 , on the outside acts as an anchor to prevent the weight of the pressure regulator at high speeds to pull the air passageway assembly  36  through the tire sidewall. Likewise, the regulator  30  and its relative large size in relation to the diameter of the sidewall bore  64  prevents the regulator from being pulled or pushed back through the bore  64 . 
         [0063]    As described above, center of the air passageway screw  36  is hollow forming the air pathway  54 . Air is thus allowed to flow from a radially outer end of the screw assembly to a radially inner end, from the filter  38  to the pressure regulator  30 . The check valve  50  is mounted to the radially inward end closest to the regulator  30  and operates as a fail-safe to prevent air from escaping back from the tire cavity through the regulator and the air passageway assembly. 
         [0064]    While the inlet air passageway assembly  36  is shown attached to the lower region of a tire sidewall, it may alternatively be placed in a chafer, shoulder or tread region. The filter  38  is used to clean air passing through the assembly  36  but may be dispensed with if desired. Also, the check valve  50  may be removed from the assembly if its fail safe function is not needed. 
         [0065]    Referring to  FIGS. 10 through 14 , an air outlet screw assembly  74  is shown for use by the subject AMT system. The outlet screw assembly  74  provides an outlet air passage from the pump groove  19  through or partially through the tire sidewall  16 . Compressed air from the pump groove  19  is thereby directed to the tire cavity  28  to bring the cavity air pressure to a desired level. Thus, the assembly  74  acts primarily as a single air passage to allow compressed air from two pump channels in the pump assembly bi-directional configuration or a single pump channel in the mono-directional configuration. The outlet screw assembly  74  furthermore provides a fail-safe valve sub-assembly that may be secured to the tire sidewall. 
         [0066]    The outlet screw assembly  74  includes an elongate tubular outlet screw body  76  formed of suitably rigid material such as plastic. The body  76  screw assembles to a valve bottom screw housing  78  which, in turn, screws into a retainer nut  80 . A check valve  82  such as a duck valve is housed and seats within the screw housing  79 , An assembly screw  84  inserts into a T-block  86  which inserts into an upper housing  102  of the screw body  76 . The upper housing  102  is bowl-shaped having a hollow interior. The assembly screw  84  has an externally threaded shaft  90  that inserts through a through bore  94  of the T-block  86  and into an internally threaded socket of the screw body  76 . A shank segment of the assembly screw  84  has an air passageway positioned to allow air entry when the assembly screw  84  is in the inserted position within screw body  76  as will be seen in  FIG. 13 . 
         [0067]    The T-block  86  is a hollow cube-shaped body having the through bore  94  extending from a top surface through the block to a bottom surface. Two cylindrical arms  96 ,  98  extend in opposite directions from the T-block  86 , each arm having an axial air passageway  100  extending therethrough. Air passing through passageways  100  enters the T-block internal through bore  94  and passes along the bore  94  to a lower side of the T-block. The T-block is shaped as a cube and fits within a hollow screw body receptacle  102 . The body  76  tapers along a mid-segment shank portion  104  to an externally threaded lower cylindrical shaft  106 . A center axial air passageway  108  extends down through the screw body  76  from the receptacle  102  at a top or outer end to a lower end of the shaft  106 . The receptacle  102  is formed having two U-shaped openings  110 ,  112  in opposite sidewalls. The openings receive the arms  96 ,  98  of the T-block upon insertion of the T-block  86  into receptacle  102 . 
         [0068]    The externally threaded shaft  106  screws into the valve housing  78 . The valve housing  78  has a annular outward projection flange  114  and a through air passageway  116 . The valve housing  78  has a cylindrical mid-segment  120  hexagonal in external configuration and a lower externally threaded post  118 . A centering post  122  projects downward from the lower end of the valve housing  78 . The check valve  124  includes an annular upper flange  124  and a center axial air passageway  126  extending end to end through the valve body. The valve  82  opens and closes at membrane  128  to allow or prevent the passage of air from the sidewall groove  19  down through the valve  82  and into the tire cavity  28 . The valve  82  is seats against a lower end of the bottom screw  78  with the annular valve flange  124  seated against an external end surface of the shank end  118 . The valve  82  seats over the post  122 . After the valve  182  is in seated position over the post  122 , the retainer nut  80  screws over the shank  118  to hold the valve  82  in place. An internal shoulder within the nut axial through bore  130  holds the valve by engagement with the valve annular flange  124  as seen in  FIG. 13 . The hex configuration of the nut  80  assists in tightening the nut body  132  to the shank  118 . A tubular end post protrusion  134  at the bottom of the nut  80  extends and assists to direct air passing from top to bottom through the outlet screw assembly into the tire cavity. The components  74 ,  76 ,  78 ,  80  and  82  have axial passageways that align in the assembled condition to create an air passageway from the arms  96 ,  98  to the tire cavity  28 . 
         [0069]    Attachment of the outlet screw assembly  74  through a tire sidewall  16  and operation of the assembly  74  will be understood from  FIGS. 10, 11, 15A and 15B . The screw assembly  74  inserts through a profiled bore  138  formed within the sidewall  16 . The bore  138  has a radially outward enlarged-diameter region  140  into which the screw body receptacle  102  is seated and a radially inward bore shank  142  receiving the screw body shaft  106 . After the screw body  76  is inserted through the bore  138 , the valve bottom screw  78  couples to the shaft  106  by threaded engagement. The valve  82  is then placed into seated position over a lower end of the threaded shank  118  and the nut  80  is screwed onto shank  118  to hold the valve in position. The components  78 ,  80 ,  82  thus reside within the tire cavity  28  and may be readily replaced in the event repair becomes necessary. The arms  96 ,  98  extending from the T-block  86  upon insertion of assembly  74  to the bore  138  are placed within opposite ends of the air passageway  19 . Air passing from the air passageway  19  of the sidewall  16  is thus directed into the T-block through the passageways  100  of the arms  96 ,  98 . From the T-block  86  the air can pass axially inward through the outlet screw assembly  74 . 
         [0070]      FIG. 15A  illustrates the outlet screw assembly  74  in the closed condition, with valve  128  closed. This condition exists when the air pressure within the tire cavity  19  is at or above a desired level. The regulator (previously described)  30  functions to sense tire pressure within the cavity  19  and to block air flow into the pumping sidewall groove  19  when no further air is required by the tire cavity  19  to maintain desired pressure. In the closed position of  FIG. 15A , the closed valve  128  additionally functions to prevent back flow of air from the tire cavity  28  through the outlet assembly  74  and into the sidewall groove  19 . 
         [0071]      FIG. 15B  represents the outlet screw assembly  74  in the open position, conducting pressurized air from the sidewall groove  19  through the assembly  74  and into the tire cavity  28 . The regulator  30 , sensing tire pressure within the cavity  19  to be lower than desired, opens to allow air to flow from inlet air passageway assembly  36  into the tire sidewall groove  19 . The groove  19  progressively forces the air along the groove  19  as the tire rotates until the air reaches and enters the outlet screw assembly  74 . The assembly  74  conducts the air down through aligned axial passageways of the assembly components, through the open valve  128 , and into the tire cavity  28 . Once air pressure within the cavity is raised to the desired preset level, regulator  30  closes off further air input into the groove  19  and pumping of air by the groove  19  ceases. 
         [0072]    It will be appreciated that the 360 degree configuration of the sidewall groove  19  makes the air pumping assembly  14  bi-directional; that is, air is pumped along the groove  19  in both directions, alternatively, depending on whether the tire is rotating forward or backward. In either direction the outlet screw assembly  74  functions to admit air into the tire cavity. The assembly arms  96 ,  98  are connected to ends of the air pumping groove  19  and thus conduct air flow in a bi-directional manner into the assembly  74  and therefrom into the tire cavity  28 . Should mono-directional air pumping be desired, the system may be altered into a mon-directional configuration as shown in  FIGS. 16 , and  FIGS. 17-19 . In the mono-directional system, the groove  19  within the tire sidewall  16  extends in an arcuate path of 180 degrees. The groove  19  extends between the location of the inlet air passageway assembly  36  and the outlet screw assembly  74 . Air flows into the system through the assembly  36  as previously described, through regulator  30 , is pumped along the groove  19  as the tire rotates (in a single direction only), and exits the groove  19  through the outlet screw assembly  74 . Mono-directional air flow along the groove  19  is thus used in the mono-directional system configuration, to re-inflate the tire cavity to a desired air pressure in the same manner previously described with regard to the bi-directional system. 
         [0073]      FIGS. 17, 18 and 19  show the components assembled to form the outlet screw assembly  138  for a mono-directional system. The components are generally the same as previously described in reference to  FIGS. 12 through 14  with the exception of modification to block  92  and screw body  76 . Like numerals that are previously used in the bi-directional system are applied in the mono-directional system of  FIGS. 17 through 19  where appropriate. In  FIGS. 17 through 19 , it will be seen that the block  92  is constructed to provide a single arm extension for positioning within the sidewall groove  19 . Accordingly, the bowl-shaped receptacle  102  receiving the block  92  during assembly only requires a single opening  112  to receive the lone arm  98 . Assembly of the outlet screw assembly  76  through a tire sidewall bore proceeds as previously explained. 
         [0074]    From the foregoing, it will be seen that the subject outlet screw assembly  74  provides an air outlet passage from the enclosed pump channel  19  at least partially through the tire structure, typically the sidewall  16 , to provide compressed air to enter into the tire cavity  28 . The air passage screw assembly  74  acts primarily as a single air passage to allow the compressed air from either two pump channels in a bi-directional system or a single pump channel in a mono-directional system entering the tire cavity  28 . Furthermore, the outlet screw assembly  74  provides additional functionality in providing a check valve to prevent undesirable backflow of air from the tire cavity and the loss of air pressure such backflow would cause. 
         [0075]    The pump outlet screw assembly  74  consists of a single piece body  76  that can be inserted into the tire structure such as sidewall  16  after tire curing. The body  76  will be pushed form the outside through a molded hole or bore  116  in the tire. The shape of the bore  116  matches the air passageway screw body  76  shape. Once through the tire and in position, the bottom valve screw  78  is fixedly attached and the valve  82 , retainer nut  84  are attached. The T-block  86  is then installed. 
         [0076]    The center pathway of the outlet screw assembly once fully assembled is hollow to allow airflow from the pumping passageway  19  to the tire cavity  28 . The T-block  86  avoids an air flow from one side of the  360  degree air passageway  19  to the other by having incorporated within the assembly screw  84  an internal directional valve  87 . See  FIG. 13 . As shown, air entering the T-block either through arm  96 ,  98  encounters an internal valve  87  within the T-block. The valve  87  directs air flow down through the outlet screw assembly toward the valve  128  but prevents air from flowing through from the T-block through the opposite arm  96 ,  98  and back into the pumping passageway  19 . 
         [0077]    The large diameter of the screw body receptacle  102  on the outside acts as an anchor to prevent the weight of the screw at high speeds to pull in from the tire sidewall. Likewise, valve bottom screw  78  having wide peripheral flange  114  acts to prevent the screw from being pulled or pushed out. The receptacle  102  has an internal thread for receiving the assembly screw shaft  90 . The shaft  106  in turn screws into the valve bottom screw socket  116 . The bottom screw  78  can thus compensate for variations in tire sidewall thickness gauge. The bottom screw  78  will be fixed with a requisite torque to the screw body  76  to reach a proper sitting and to prevent air leakage. The check valve  82  prevents air from leaking out of the tire as described above. The outside of the screw body  76  allows it to screw into position within the bore  116  during assembly. 
         [0078]    The outlet screw assembly  74  may be attached alternatively to a tire chafer, shoulder or tread. It may be used without the check valve  82  if such a function is not deemed necessary. 
         [0079]    Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.