Patent Publication Number: US-9415640-B2

Title: Valve stem located control regulator for an air maintenance tire

Description:
FIELD OF THE INVENTION 
     The invention relates generally to air maintenance tires and, more specifically, to a control and air pumping system for use in an air maintenance tire. 
     BACKGROUND OF THE INVENTION 
     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 feature within a tire that will self-maintain the tire air pressure in order to compensate for any reduction in tire pressure over time without a need for driver intervention. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, a control valve assembly proximally mounts to a tire valve stem and operably controls a flow of pressurized air through the tire valve stem from either an external pressurized air source or an ancillary tire-mounted pressurized air source mounted within a tire sidewall. The control assembly includes a bi-directional air distribution block having a plurality of air pathways, each air pathway coupled to a respective conduit connected to a tire-mounted air pumping tube. The pathways alternatively operate to deliver ambient non-pressurized air to the air pumping tube in response to the direction of tire rotation against a ground surface. 
     In another aspect, each of the air pathways comprises multiple check valves serially connected within the air distribution block, the check valves within each pathway selectively opening and closing in response to the direction of tire rotation against a ground surface. 
     According to another aspect, the pressure control assembly includes a relief valve mounted to vent pressurized air from the air pathways through the bi-directional block. The relief valve operably opens to vent pressurized air when an air pressure within the tire cavity is at or above a predetermined optimal inflation level, and the relief valve operably closes when air pressure within the tire cavity is below the predetermined optimal inflation level. 
     In another aspect, the pressure control assembly controls pressurized air flow from the pumping tube by controlling the flow of ambient non-pressurized air to the tire-mounted tube responsive to a detected air pressure level within the tire cavity. 
     Pursuant to another aspect, the valve stem is sized and configured to extend through a rim body and the bi-directional air distribution block. The pressure control assembly mounts to a surface of the rim body at the control location in proximal relationship with the valve stem. 
     The air pumping tube, in another aspect, mounts within a flexing region of a tire wall closes and opens segment by segment in reaction to induced forces from the tire flexing region as the flexing region of the tire wall rotates opposite a rolling tire footprint. 
     DEFINITIONS 
     “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. 
     “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
     “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
     “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. 
     “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
     “Duck Valve” is a check valve manufactured from rubber or synthetic elastomer, and shaped like the beak of a duck. One end of the valve is stretched over the outlet of a supply line, conforming itself to the shape of the line. The other end, the duckbill, retains its natural flattened shape. When pressurized air is pumped from the supply line through the duckbill, the flattened end opens to permit the pressurized air to pass. When pressure is removed, the duckbill end returns to its flattened shape, preventing backflow. 
     “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
     “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. 
     “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. 
     “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. 
     “Inward” directionally means toward the tire cavity. 
     “Lateral” means an axial direction. 
     “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. 
     “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. 
     “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. 
     “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. 
     “Outward” directionally means in a direction away from the tire cavity. 
     “Peristaltic” means operating by means of wave-like contractions that propel contained matter, such as air, along tubular pathways. 
     “Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire. 
     “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. 
     “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. 
     “Tread element” or “traction element” means a rib or a block element defined by having a shape adjacent grooves. 
     “Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view of a tire with a valve stem mounted bi-directional AMT pressure control system. 
         FIG. 2  is an exploded perspective view of the stem mounted bi-directional AMT pressure control system. 
         FIG. 3  is a side view of the tire with the valve stem mounted bi-directional AMT pressure control system. 
         FIG. 4  is a side view of the tire with the valve stem mounted bi-directional AMT pressure control system showing the pump tube closed from contact with the road forcing air flow. 
         FIG. 5  is a partial section perspective view from  FIG. 3  of a first embodiment of the stem mounted bi-directional AMT pressure control system. 
         FIG. 6A  is a perspective view of the stem mounted bi-directional AMT pressure control system. 
         FIG. 6B  is an opposite side perspective view of the pressure control system. 
         FIG. 7  is an alternate angle perspective view of the stem mounted bi-directional AMT pressure control system. 
         FIG. 8  is an opposite side perspective view of the stem mounted bi-directional AMT pressure control system. 
         FIG. 9A  is an exploded perspective view of the first embodiment of the stem mounted bi-directional AMT pressure control system. 
         FIG. 9B  is an exploded perspective view of an alternative second embodiment of the pressure control system. 
         FIG. 10A  is an angle perspective view of the first embodiment of the stem mounted bi-directional AMT pressure control system. 
         FIG. 10B  is an angle perspective view of the second embodiment of the AMT pressure control system. 
         FIG. 11A  is an opposite angle to  FIG. 9A  exploded perspective view of the first embodiment of the stem mounted bi-directional AMT pressure control system. 
         FIG. 11B  is an opposite angle to  FIG. 9B  exploded perspective view of the second embodiment of the pressure control system. 
         FIG. 12A  is a section view of a first cold set inflation control regulator embodiment with the tire cavity pressure above the set pressure, not allowing air to pass. 
         FIG. 12B  is a section view of the first cold set inflation control regulator embodiment with the tire cavity pressure below the set pressure, allowing air to pass. 
         FIG. 13A  is a section view of an alternative second cold set inflation control regulator embodiment with the tire cavity pressure above the set pressure, not allowing air to pass. 
         FIG. 13B  is a section view of the second cold set inflation control regulator embodiment with the tire cavity pressure below the set pressure, allowing air to pass. 
         FIG. 14A  is a section view of a third cold set inflation control regulator embodiment with the tire cavity pressure above the set pressure, not allowing air to pass. 
         FIG. 14B  is a section view of the third cold set inflation control regulator embodiment with the tire cavity pressure below the set pressure, allowing air to pass. 
         FIG. 15  is a partially sectioned perspective view of the bi-directional block. 
         FIG. 16  is a partially sectioned perspective view of the bi-directional block (first flow direction) showing the air coming from the control regulator through a duck valve assembly, around a duck valve assembly, through a fitting assembly and out to the pump tube. 
         FIG. 17  is a partially sectioned perspective view of the bi-directional block (first flow direction) showing the air coming from the pump tube into a fitting assembly, through a duck valve assembly and up into a groove. 
         FIG. 18A  is a partially sectioned perspective view of the bi-directional block (first flow direction) showing the air continuing from the groove through a duck valve assembly, into the valve stem and into the tire cavity in the condition that the tire cavity is at low pressure. 
         FIG. 18B  is a partially sectioned perspective view of the bi-directional block (first flow direction) showing the air continuing from the groove through an exhaust valve in the condition that the tire cavity is at or above the desired pressure. 
         FIG. 19  is a partially sectioned perspective view of the bi-directional block. 
         FIG. 20  is a partially sectioned perspective view of the bi-directional block (second flow direction) showing the air coming from the control regulator through a duck valve assembly, around a duck valve assembly, through a fitting assembly and out to the pump tube. 
         FIG. 21  is a partially sectioned perspective view of the bi-directional block (second flow direction) showing the air coming from the pump tube into a fitting assembly, through a duck valve assembly and up into a groove. 
         FIG. 22A  is a partially sectioned perspective view of the bi-directional block (second flow direction) showing the air continuing from the groove through a duck valve assembly, into the valve stem and into the tire cavity in the condition that the tire cavity is at low pressure. 
         FIG. 22B  is a partially sectioned perspective view of the bi-directional block (second flow direction) showing the air continuing from the groove through an exhaust valve in the condition that the tire cavity is at or above the desired pressure. 
         FIG. 23  is a cross sectional view through the assembled regulator and bi-directional block. 
         FIG. 24A  is a sectional schematic view through the assembled regulator and bi-directional block showing the regulator valve in the closed position 
         FIG. 24B  is a sectional schematic view through the assembled regulator and bi-directional block showing the regulator valve in the open position. 
         FIG. 25  is a top perspective view of the regulator cover plate. 
         FIG. 26  is a bottom perspective view of the regulator valve housing component of the regulator cover plate. 
         FIG. 27  is a top perspective view of the regulator cover plate with the regulator valve housing removed. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1, 2, 3 and 4 , a tire assembly  10  includes a tire  12 , a control system  14  for controlling a peristaltic pump assembly  15 , and a tire rim body  16 . The tire mounts in conventional fashion to the rim body  16 . The tire is of conventional construction, having a pair of sidewalls  18 ,  20  (only sidewall  18  being shown) extending from opposite bead areas  22 ,  24  (only bead area  22  being shown) to a crown or tire tread region  26 . The tire and rim body enclose a tire cavity  28  (see  FIG. 5 ). 
     As seen from  FIGS. 2 and 3 , the peristaltic pump assembly  15  includes an annular air tube  30  that encloses an annular passageway  32 . The tube  30  is formed of a resilient, flexible material such as plastic or rubber compounds that are capable of withstanding repeated deformation cycles. So constructed, the tube may deform within a tire into a flattened condition subject to external force and, upon removal of such force, return to an original sectional configuration. In the embodiment shown, the cross-section of the tube in an unstressed state is generally circular but other alternative tube geometries may be employed if desired. The tube is of a diameter sufficient to operatively pass a requisite volume of air sufficient for the purpose of pumping air into the tire cavity  28  to maintain the tire  12  at a preferred inflation pressure. 
     The peristaltic principles of incorporating a deformable air tube within a tire are shown and described in U.S. Pat. No. 8,113,254, incorporated herein by reference in its entirety. In the patented system, the tube is incorporated within an annular tire passageway formed within the tire proximate a tire bead region. As the tire rotates air from outside the tire is admitted into the tube and pumped along the air tube by the progressive squeezing of the tube within the tire as the tire rotates. Air is thus forced into an outlet valve and therefrom into the tire cavity to maintain air pressure within the tire cavity at a desired pressure level.  FIG. 4  shows the general operational principle of the air tube pumping an air flow along the tube as the tire rotates against a ground surface. 
     The tube  30  mounts closely within a groove in the tire and sequentially flattens as the tire rotates. The segment by segment flattening of the tube as the tire rotates operates to pump air along the air passageway  32 , air which is then directed into the tire cavity  28  to maintain air pressure. A peristaltic pumping system employing a tube within a sidewall groove is shown in issued U.S. Pat. No. 8,042,586, also incorporated herein by reference in its entirety. 
     Referring to  FIGS. 2, 4, and 5 , the pump tube  30  is generally annular and circumscribes a lower tire sidewall  18  region proximate to a bead region  22 . However, other configurations for the air tube may be devised without departing from the invention. Opposite ends of the tube  30  connect into an inline connector block  34 . Conduits  36  and  38  are coupled to the connector block  34  and to respective opposite ends of the pumping tube. The conduits  36 ,  38  follow a predetermined path around a rim flange  42  to the air flow bi-directional block  40 A, B affixed to an underside  44  of the rim body  16 . Conduits  36 ,  38  represent air inlet/outlet channels to and from the air pumping tube  30 . In the pumping mode, forward revolution of the tire, one conduit delivers air to the pumping tube and the other conduit conducts air pressurized by the pumping tube to the bi-directional block  40 A, B. In the reverse rotational direction of the tire, the conduits  36 ,  38  functionally reverse. 
       FIGS. 5, 6A, 7, 8, 9A, 10A, and 11A  show a first embodiment for a control regulator/bi-directional block set up. The control valve regulator uses a cold set inflation control of inlet air into the air tube  30 . In such a system, the air tube will not be pumping air when the control system valve is in the off or closed position (no air input into tube) and will only operate to pump air when the control valve is in the on or open condition (air flow into tube). In the cold set control regulator, a spring regulated actuator with pressure sensing capability is used to open and close air flow to the tube  30 . If cavity pressure is less than set pressure (cold inflation set pressure), the regulator valve opens and allow air into the air tube  30 . If cavity pressure is higher than set pressure (cold inflation set pressure), the regulator valve will close and no air will be allowed to flow into the tube  30 . Three designs for a cold set regulator valve are shown in  FIGS. 12A through 14B . 
     An alternative second embodiment of a control regulator/block set up is shown in  FIGS. 6B, 9B, 10B and 11B . In the second embodiment control regulator approach, outlet pressurized air from the pumping tube is controlled by a spring regulated pressure relief valve, rather than an air inlet control regulator valve system. Setting the relief valve controls the flow of air from the pumping air tube  30  into the tire cavity  28 . If the cavity pressure is less than set pressure (ceiling inflation set pressure), the valve opens and allows air into the tire cavity when built-up air pressure in the pump tube is higher than the pressure in the tire cavity. If the cavity pressure is higher than set pressure (ceiling inflation set pressure), the pumped air will release through the relief valve and either bypass back into the pump or release to atmosphere. 
     In both the first and second control regulator/block set up configurations, a pumping of air from the tube  30  to the tire cavity can occur when the tire is rotating in either a forward or reverse direction. The bi-directionality in pumping air from the tube  30  is made possible by an air flow bi-directional block  40 A, B containing dual air flow paths, each path defined by a coupled pair of check valves. The four check valves within the dual parallel air flow paths may be augmented by a fifth check valve for extra control. Thus, the control system  14  employed in the subject invention may be configured as an inlet air control system employing an inlet control regulator or an outlet pressurized air control system, both the inlet and outlet systems using a bi-directional air distribution block  40  A, B. 
     With reference to  FIGS. 5, 6A, 7, 8, 9A, 10A, and 11A, 25, 26, 27 , the air flow directional block  40 A is generally a cubic body formed by sidewalls  46 ,  48 ,  50 A, B,  52 , bottom wall  54  and a top side  56 . A top cover plate  58 A attaches over the top side  56  of the cubic body and the control regulator  68 A. An elongate cylindrical control regulator valve housing  60 A is attached to an outward surface of the top cover plate  58 A by suitable means, the housing  60 A having an axial through bore  62 . The cover plate  58 A is formed having a circular through bore  64  sized to accept a protruding tire valve stem as explained below. A set of four corner assembly apertures  66  extend through the top panel. As seen in  FIGS. 26 and 27 , deformations forming part of the control assembly outlet air passageways  154 A,  155  extend along the underside of the housing  60 A. Complementary deformations are formed within and extend along the upper surface of the top cover plate  58 A. When united, the deformations form the enclosed outlet air passageways  154 A,  155 . Attachment of the housing  60 A to the cover plate  58 A completes the formation of the passageways  154 A,  155 , whereby providing parallel outlet air passageways from the control assembly housed within the housing  60 A to the bi-directional distribution block  40 A. 
     A control valve assembly  68 A, C, also referred herein as the “control regulator”, in each of three alternative embodiments described herein is housed within the bore  62  within cylindrical control regulator housing  60 A. A recess  70  is defined within the top side  56  of the cubic body of block  40 A, B. The top side  56  further is formed to provide four corner assembly sockets  72  and a through bore  74  dimensioned to accept a tire valve stem  100  therethrough. A pair of duck valve-seating sockets  76 ,  78  extend into the top side  56  at opposite corners of the air collection chamber  70 . 
     Four assembly pins  80  extend through the apertures  66  and into the sockets  72  to affix the cover plate  58 A, B to the top side  56  of the block  40 A, B, whereby enclosing the air collection chamber  70 . A valve-stem attachment nut  82  is provided for securing a tire valve stem  100  to the block  40 A, B. A pair of duck valve sockets  84 ,  86  (valve  86  not shown in  FIG. 9A ) extend through the block sides  48 ,  52 , respectively. A pair of air inlet/outlet sockets  88 ,  90  extend through the block side  46  positioned in spaced apart relationship as shown. The duck, or “check” valves  92 ,  94 ,  96 ,  98  are of a commercially available type, also referred herein as “check” valves. Duck valve components  92 ,  94  extend transversely into the bi-directional block  40 A, B, residing respectively within sockets  84 ,  86 , and duck valve components  96 ,  98  extend vertically into the block  40 A, B, residing respectively within sockets  76 ,  78 . The valve components  92 ,  98  and the valve components  94 ,  96  are paired to create two parallel air flow paths through the block  40 A, B, providing dual paths from the control regulator  68 A to the inlet/outlet sockets  90 ,  88  respectively. The valves are configured conventionally as duck-bill valves that include a slitted membrane that opens and closes responsive to application of air pressure. Other known types of check valves may be used if desired. Outward ends  99  of the duck valves  96 ,  98  are coupled to the control valve assembly  68 A by the formed pair of outlet conduits  154 A,  155  to create the two parallel air flow paths conducting air from the control valve assembly  68 A to the bi-directional block  40 A, B. 
     A valve stem  100  of the tire is internally modified to provide an internal pressurized air collection chamber  174  at a base end. The internal air collection chamber  174  of the valve stem is accessible by a transverse inlet passageway  170  extending through the valve stem. The valve stem  100  is received and projects from through-bore  64  of the block  40 A, B. The valve stem  100  has an axially outward screw threaded end housing a valve component  101  of conventional configuration. The valve component within end  101  is used to input pressurized air sourced from an external air input through the valve stem and into the tire cavity. As used herein, the valve (not shown) housed within end  101  of the valve stem  100  is referred to as a “primary input valve”. The primary input valve admits pressurized air in conventional fashion from a primary pressurized air external source (not shown) into the air collection chamber  174 . From the air collection chamber  174  the pressurized air from the primary pressurized air external source is directed into the tire air cavity  28  to re-pressurize the cavity. 
     The delivery of pressurized air to the tire cavity pursuant to the invention thus may be secured from dual sources The primary input valve within valve stem end  101  conventionally admits pressurized air from a primary external air source. In addition and complementary therewith, the air pumping tube  30  pressurizes the cavity  28  under the control of regulator  68 A on an as needed basis as the tire rolls against a ground surface. 
     The coupling nut  82  affixes to the external screw threads of a protruding end  101  of the valve stem  100  to secure the valve stem to the block  40 A, B. A screw-in plug  102  and sealing O-ring  104  inserts into the valve socket  86  to secure the valve  94  in position. Likewise, screw-in plug  106  and sealing O-ring  180  engages into the socket  84  to secure the valve  92  within the block  40 A, B. The air inlet/outlet conduits  36 ,  38  include end fittings  110 ,  112  that couple to connectors  114 ,  116  within the inlet/outlet sockets  88 ,  90  of the block  40  A, B, respectively. So coupled, both of the inlet/outlet conduits are enabled to conduct air from the block  40 A, B to the air tube  30  and conduct pressurized air from the air tube  30  back to the block. Inlet and outlet functions switch back and forth between the conduits  36 ,  38  as dictated by the direction of tire rotation. The pumping tube  30  is thus capable of delivering pressurized air through the block  40 A, B to the tire cavity with the tire  12  rotating in either a forward or a reverse direction. An internally threaded access opening  122  through the bottom floor of the air collection chamber  70  is used in the assembly of the block  40 A, B. Once assembly is completed, screw  120  is screw threaded attached into the access opening  122  to seal off the interior of the block  40  for its intended air distribution operation. 
       FIG. 11A  shows the  FIG. 9A  assembly described above from a reverse angle and  FIG. 10A  shows the assembled control assembly bi-directional block  40 A.  FIGS. 12A and 12B  and  FIGS. 24A and 24B  are sectional schematic views of the control regulator  68 A in the closed and open positions, respectively.  FIG. 23  shows a sectional view through the assembled control valve assembly  68 A and bi-directional block  40 A.  FIG. 24A  shows an enlarged view of the control regulator  68 A of  FIG. 23  in the closed position.  FIG. 24B  shows the enlarged view of the control regulator  68 A in the open position. The embodiment of  FIGS. 9A, 12A, 12B, 23, 24A and 24B  represents a first one of three alternative embodiments of the stem mounted bi-directional AMT pressure control system disclosed herein. Control valve assembly  68 A, mounted to the block  40 A controls air flow into the block  40 A and, hence, the air tube  30  ( FIG. 5 ). A cold set inflation level is applied to the assembly  68 A to control opening and closing of the valve assembly and, thereby, air flow to the air pumping tube. Three alternative configurations of the control valve assembly  68 A are shown in  FIGS. 12 through 14  and described below. 
     With reference to  FIGS. 9A, 12A, 12B, 23, 24A, 24B , a first cold set inflation control regulator embodiment  68 A is shown suitable for assembly into longitudinal bore  62  of the control regulator housing  60 A. The control regulator of  FIGS. 24A, 24B  includes a filter element  69  in the assembly whereas the simplified assembly of  FIG. 12A, 12B  does not. 
     Valve Closed Position 
     As shown in  FIGS. 12A and 24A , the regulator is in the closed position with the tire cavity pressure above the set pressure, not allowing air to pass. The assembly  68 A includes an elongate actuator piston  124 A having a spherical nose  126 A at a forward end  128 A; an annular flange  130 A disposed toward a rearward end  132 A. An annular spring stop flange  134  extends into the center bore  62 A toward a forward end of the bore  62 A. A coil spring  136 A encircles the piston  124 A, positioned between the annular flange  130 A and the stop flange  134 . An annular diaphragm plug  138 A has a through-hole receiving a rearward end portion of the piston  124 A within a rearward region of the housing bore. The plug  138 A functions as a guide for reciprocal axial movement of the piston  124 A. A generally circular flexible diaphragm component  140 A is positioned to the rear of the guide plug  138 A within the bore  62 A. The diaphragm component  140 A is formed of resilient elastomeric material capable of deformation when subject to pressure against an outward surface and resumption of an original configuration when that pressure is removed or lessened. Diaphragm component  140 A includes a protruding finger  202  that is captured and secured within the piston  124 A. Deformation of the diaphragm component  140 A as shown operatively moves the piston  124 A axially into a closed, seated position. A threaded insert  142 A screws into a rearward end of the housing  60 A and encloses the assembly within bore  62 A. The insert  142 A has a centrally disposed pressure sensing cavity  143 A positioned adjacent the outward surface of diaphragm component  140 A. A tubular conduit  144 A connects the cavity  143 A to a passageway  145  extending through block  40 A. The passageway  145  communicates with the tire cavity to convey tire cavity pressure to the cavity  143 A located opposite the outward surface of the diaphragm component  140 A. 
     At the forward end of the housing  60 A a set pressure adjustable threaded filter insert  146 A is threaded into the housing, closing the bore  62 A. The extent to which the screw  146 A is screwed in will determine the compression force in coil spring  136 . The insert  146 A is configured forming a seat or pocket  148 A positioned opposite the spherical nose  126 A of the piston  124 A. The spherical nose  126 A of the piston  124 A is fitted with a cover  150 A formed of elastomeric material composition for sealing purposes. The screw  146 A has an axial air inlet channel  152  extending therein from the forward end in communication with the seat  148 A. In the configuration of  FIGS. 24A and 24B , a filter element  69  is disposed within the air inlet channel  152 . A pair of spaced apart air outlets  154 A  155  (one of which being shown in the sectional views) are positioned as outlets from the body  60 A and extend in air flow communication with the inlet channel  152  when the piston  124 A is in the open or unseated position. 
     It will be appreciated that the piston  124 A axially moves reciprocally within the control regulator body  60 A. In the forward, “valve closed”, location shown by  FIGS. 12A and 24A , the spherical nose  126 A of the rod  124 A seats against the seat  148 A and blocks off air flow from the air inlet channel  152  into the body bore  62 A. Air is therefore blocked from the pair of air outlets  154 A,  155  to the bi-directional block  40 A. Screw adjustment of the adjustable screw  146 A inward or outward sets the compression force exerted by the spring and thereby dictates the air pressure against the outward surface of the diaphragm component  140 A required to overcome this preset spring bias. 
     Valve Open Position 
     A high tire cavity pressure level presented by the passageway  144 A causes the diaphragm  140 A to push against the piston rod  124 A with sufficient force to overcome spring bias force and maintain the piston in its seated or “closed” position. The piston  142 A is pressured against seat  148 A whenever air pressure within the tire cavity is at or above rated pressure level. A lower pressure within the cavity will reduce deformation of the diaphragm component and cause the piston to move rearwardly into an “open” position under influence of spring  136 A as seen in  FIGS. 12B and 24B . The spherical nose  126 A disengages from its seat  148 A in the “open” rod position, allowing air flow into and through the valve. In the open valve position, air is admitted into the bore  62 A from the inlet channel  152  and directed out of the outlet port passageways  154 A,  155  to the bi-directional block  40 A. The bi-directional block  40 A, as explained below, directionally routes the air from the control regulator along one of two parallel air flow paths to the air pumping tube  30  mounted within tire  12 . Rotation of the tire  12  over a ground surface pressurizes the air within the tube  30  and outlets the pressurized air back through the bi-directional block and into the tire cavity. The air pressure within the tire cavity  28  is thereby brought back up to rated or recommended air pressure level. 
       FIGS. 12B and 24B  show an outward deformation of diaphragm  132 A placing the control regulator piston in the open, unseated condition. Air from the filter layer  69  is admitted past the unseated spherical nose  126 A of piston  124 A for exit out the outlet passageways  154 A,  155  to the bi-directional block  40 A. The actuator guide  138 A centers the piston  124 A during reciprocal axial movement of the piston between open and closed positions within the bore  62 A. It will be appreciated that the air tube  30 , under control from the control regulator valve assembly  68 A, only receives air to compress when air is allowed to flow to the bi-directional block  40 A. When air flow is blocked by the valve assembly  68 A, air flow to the bi-directional block  40 A and to pumping tube  30  terminates. By limiting the pumping operation of the air tube  30  to only those times when the tire pressure is low, cyclical failure of the component parts of the air maintenance system due to fatigue is avoided. When air pressure within the tire cavity is low, air flow to the pumping tube  30  is initiated, allowing the bi-directional block  40 A to deliver air to and receive pressurized air from the pumping air tube  30 . 
     For example, the control regulator of  FIGS. 9A, 10A, 11A, 12A, 24A  may be set at a pressure of 100 psi by appropriate adjustment of the compression force of spring  136 A, with initial tire cavity pressure of 90 psi. The lower than desired tire cavity pressure will be communicated to the outward side of diaphragm  140 A through the passageway from cavity  144 A. The compression set of spring  136 A will enable to spring to uncoil, forcing the piston axially to the rear, opening the valve as seen in  FIGS. 12B and 24B . Air flow through the valve and through the passageways  154 A,  155  is directed to the bi-direction block and from the block to the air pumping tube  30 . The tube  30  pumps the air to a pressure greater than 90 psi and directs the pressurized air back to and through the block  40 A into the tire cavity. When the tire cavity achieves a desired pressure of 100 psi., the diaphragm  140 A is pressured back into its condition of  FIGS. 12A and 24A , forcing the piston  124 A forward into the seated, “closed” position. Further air flow through the control regulator to the bi-directional block  40 A is thereby blocked until required by tire cavity low pressure. 
       FIGS. 13A and 13B  show an alternatively configured control regulator valve  156  in the closed and open positions, respectively. The inlet  158  through the valve is placed through the regulator body  60 B rather than the set pressure adjustable screw  146 B. A filter element such as  69  (not shown) may be incorporated into the inlet passageway if desired. Operationally, the second embodiment of the valve functions as described above for the first embodiment. A lower than desired air pressure in the tire cavity causes the piston  124 B to axially move to the rear, unseating the rod forward end  126 B and allowing air to flow into the valve body through inlet  158  as seen in  FIG. 13B . Air flow to the bi-directional block and the air pump is enabled until a desired tire cavity air pressure is achieved. Upon reaching the preset tire cavity pressure, the piston  124 B moves forward and into the closed position shown in  FIG. 13A . It is to be understood that the regulator valve  156  shown in  FIGS. 13A and 13B  is similar in structure to the regulator valve  68 A shown in  FIGS. 12A and 12B . As a result, the component numbers are similar, with the letter “B” following the numbers in  FIGS. 13A and 13B , while the letter “A” follows the numbers in  FIGS. 12A and 12B . 
       FIGS. 14A and 14B  show a third alternative control regulator valve  68 C in the closed position ( FIG. 14A ) and the open position ( FIG. 14B ). A filter element such as  69  (not shown) may be incorporated into the inlet passageway if desired. In the embodiment shown, the housing  60 C is configured to have an inlet opening  162  to admit air from the filter  69  into the housing. The diaphragm seal or centering guide  138 C is adapted having a threaded post to which a set pressure adjustment collar  168  attaches. Rotation of the collar  168  adjusts the compression of the spring  136 C which, as described previously, creates a threshold pressure that opens and closes the valve. The seat  166  for the piston  124 C is formed by the regulator housing  60 C. With the valve in the closed position of  FIG. 14A , the seated piston  124 C prevents air from flowing from the filter  69  into the regulator housing. The diaphragm  140 C, pushed by tire cavity pressure, maintains the piston  124 C in the closed, seated position. When air pressure falls below desired level in the tire, as seen in  FIG. 14B , the valve opens. Piston  124 C, under spring bias, moves axially out of the seat  166  allowing air to enter the housing through channel  162 . Air is passed through the regulator housing as shown and exits at passageway  164  to the bi-directional block for distribution to the air pumping tube  30 . It is to be understood that the regulator valve  68 C shown in  FIGS. 14A and 14B  is similar in structure to the regulator valve  68 A shown in  FIGS. 12A and 12B  and to the regulator valve  156  shown in  FIGS. 13A and 13B . As a result, the component numbers are similar, with the letter “C” following the numbers in  FIGS. 14A and 14B  while the letter “A” follows the numbers in  FIGS. 12A and 12B , and the letter “B” follows the numbers in  FIGS. 13A and 13B . 
     Referring to  FIGS. 15, 16 and 19 , the internal configuration of the bi-directional block  40 A, B is shown in broken perspective.  FIG. 15  is a partially sectioned perspective view of the basic bi-directional block internal configuration.  FIG. 16  is a partially sectioned perspective view of the bi-directional block (in a first flow direction) showing the air coming from the control regulator of  FIG. 9A  described above. As shown in  FIG. 15  and described above, the inlet/outlet conduits  36 ,  38  represent parallel pathways for air to flow to and from the air pumping tube  30 . The conduits  36 ,  38  have connectors  114 ,  116  that connect into the block  40 A, B and communicate air to and from the air tube  30  (not shown). Check valves  92 ,  94 ,  96 ,  98  mount into sockets within the block  40 A, B and create an air flow scheme designed to bi-directionally direct air to and from the air tube. Check valves  98  and  92  are mounted at right angles to each other and at right angles with the connector  116 . Valves  98 ,  92 , and connector  116  form part of what is herein referred to as a “first” block air pathway. Valves  96 ,  94 , and connector  114  are likewise mounted at right angles and form part of what is herein referred to as a “second” block air pathway. The first and second block air pathways are located at opposite sides of the block  40 A B. Check valves  96 ,  98  connect externally from the block  40 A, B to the outlet air pathways  154 A,  155  of the control valve regulator  68 A (not shown). 
     The valve stem  100  inserts into throughbore  74  from the underside of the block  40 A, B with the screw threaded end  101  of the valve stem  100  protruding from the throughbore  74  at a top side of the block  40 A, B. The valve stem  100  includes an air inlet passageway  170  extending transversely through the valve stem in airflow communication with an internal valve stem chamber  174  (reference  FIG. 22A ). A pressure relief valve  172  mounts into the block and operationally acts to vent pressurized air from the block  40 A, B when the tire cavity is at full air pressure. 
       FIG. 16  shows the air flowing through the block  40 A, B from the regulator in the first air flow direction. Air enters the block  40 A, B from the control regulator through the check valve  98  and is directed through an internal axial chamber  176  within the plug  106 , bypassing the check valve  92 . From the plug chamber  176 , air flows through the connector fitting  116  and into conduit  38  to the pump tube  30 . The air upon entering the pump tube is compressed as the tire rolls along a ground surface. 
     The air from the control regulator is routed through the valve  98 , around the check valve  92 , through the air cavity  176  within hollow screw  106 , into the axial passageway of connector  116 , and finally into the outlet conduit  38 . The air exits through the outlet conduit  38  to the air tube  30  (not shown), mounted within the tire sidewall. As explained previously, air from the control regulator will only be inputted into the check valve  98  of distribution block  40 A, B from the control regulator when the air pressure within the tire cavity is below a preferred level. Cavity pressure at or above rated level will cause the regulator to block air flow to the block  40 A, B. 
       FIGS. 17, 18A, and 22A  show the return of pressurized air from the pumping tube  30  into the block  40 A, B. Pressurized air from the pumping tube follows a similar curvilinear path through the block  40 A, B to finally enter the valve stem  100  and from the valve stem the tire cavity.  FIG. 17  is a partial perspective view of the internal block from an opposite side to  FIG. 16 . As shown in  FIGS. 17, 18A and 22A , pressurized air from the pump tube  30  enters from conduit  36  into the block  40 A, B and flows through connector fitting  114 , through shank-located air chamber  178  of the assembly screw  102 . The pressurized air opens and continues through check valve  94  along a formed enclosed block channel  180  into an air chamber  182  forwardly disposed from the relief valve  172 . A fifth check valve  184  is positioned within the block  40 A, B between the air chamber  182  and location of the valve stem  100 . A formed air passageway  186  within the block  40 A, B connects air flow from the check valve  184  to the transverse air passageway  170  extending through the valve stem  100 . Thus, pressurized air opens and is routed through the check valve  184 , follows the air passageway  186 , and enters the valve stem air collection chamber  174  by way of passageway  170 . From the air collection chamber  174 , the pressurized air is directed to the tire cavity to raise air pressure within the cavity to the desired level. 
       FIG. 18A  is a partially sectioned perspective view of the bi-directional block  40 A, B (first flow direction) showing the return of pressurized air from the air pumping tube  30  (not shown) through the block  40 A, B and into the valve stem  100 .  FIG. 22A  is a similar sectioned perspective view from a reverse angle showing pressurized air flow through the block  40 A, B to the tire cavity. It will be appreciated that the air flow paths described herein are directed through internal channels formed within and by the distribution block  40 A, B. Removal of sections of block  40 A, B, including portions forming the internal channels, are depicted for the purpose of illustration. The pressurized air exits check valve  184  into passageway  186  and is directed thereby through the portal  170  of the valve stem  100  into the internal air collection chamber  174  within a base end of the valve stem. From the collection chamber  174 , the pressurized air is directed to the tire cavity to restore cavity pressure to its preferred level. 
       FIG. 18B  is a partially sectioned perspective view of the bi-directional block  40 B (first flow direction) showing in greater detail the internal configuration of relief valve  172 . If the tire cavity is at or above the desired pressure, pressurized air from the air pumping tube  30  cannot reach the tire cavity but is instead exhausted to atmosphere through the relief valve  172 . The relief valve is configured as an adjustable check valve as shown but other relief valve configurations may be employed if desired. As shown in  FIG. 18B , pressurized air enters inlet  188  of the relief valve  172 . An internal check valve  189  is positioned within an axial air chamber  192 . A coil spring  196  is captured within the chamber  192  and exerts a spring force on ball  198 . The ball  198  seats in a closed position to block air flow. When air pressure at the forward end of the check valve exceeds the preset compression force of the spring  196 , the ball  198  unseats and air flow is enabled through an outlet passage  194  from the valve and into a threaded spring compression-adjustment cap  190 . The cap  190  has an exhaust outlet  192  extending therethrough. The cap has screw threads  200  to adjust the compression force on the spring  196 . It will be appreciated that pressurized air flow through the block  40 B is directed to the forward end of the relief valve by the groove  180 . If the air pressure within the tire cavity is higher than the pressure of the air flow through groove  180 , the air will not be admitted through the check valve  184 . The air flow pressure will open the relief valve and be allowed to vent through the valve. 
       FIGS. 17 and 18B  show the block  40 B receiving pressurized air pumped from the air tube  30  (not shown) mounted to the tire  12 . Pressurized air from the pumping tube is routed through the inlet/outlet conduit  36  to the block  40 B, entering through coupling connector  114  and following a serpentine path through the hollow axial center chamber  178  of the screw  102 . Duck valve  94 , seated within the screw  102 , opens and conducts the air flow into the relief valve  172  if the tire cavity pressure is at or greater than specified level. Relief valve  172  operates to vent the pressurized air in the event that the cavity pressure is at or above desired set pressure. If the cavity pressure is lower than set pressure, the pressurized air from the pumping tube is directed through check valve  184  into the channel  170  of the valve stem  100  and into the center air collection chamber  174  of the valve stem. From there, the pressurized air is sent to the tire cavity, bringing cavity air pressure up to desired level. As explained previously, air to the block  40 B only occurs when the control regulator opens. Pressurized through the block  40 B to the valve stem  100  and therefrom to the tire cavity only occurs if the relief valve  172  remains closed. Should air pressure within the tire cavity be sufficiently high, the relief valve  172  will open and vent the pressurized air passing through block  40 B. 
       FIG. 20  is a partially sectioned perspective view of the bi-directional block (second flow direction) showing the air coming from the control regulator through the duck valve assembly  96 , around the duck valve assembly  94 , through the fitting assembly  114  and out to the pump tube  30  by way of conduit  36 . The block  40 A, B is constructed such that the first and second air pathways are formed by symmetric mirror image arrangement of the check or duck valves. The above description of the conduction of air through the block along the first pathways will thus be understood to apply equally to the operation during conduction of air through the block  40 A, B along the second air pathway. 
       FIG. 21  is a partially sectioned perspective views of the bi-directional block (second flow direction) showing the air coming from the pump tube into a fitting assembly, through the duck valve assembly  92  and through an internal block air channel to check valve  184 . Pressurized air is thereby conducted into the valve stem via the second air flow path. 
       FIG. 22B  is a partially sectioned perspective view of the bi-directional block (second flow direction) showing the air continuing from the groove through an exhaust valve in the condition that the tire cavity is at or above the desired pressure. 
     With reference to  FIG. 23 , the assembled regulator plate  58 A and bi-directional distribution block  40 A is shown. The regulator cover plate  58 A assembles over the block  40 A, completing the formation of outlet air passageways  154 A,  155  into the block  40 A. The passageway  144 A of the regulator control assembly  68 A establishes air flow communication with passageway  145  through the block. Passageway  145  intersects the passageway  186  which communicates with the internal chamber  174  of the valve stem through transverse opening  174 . The chamber  174  is connected to the tire cavity so that air pressure of the cavity is communicated through the block passageway  145  and the regulator passageway  144 A to the outward side of diaphragm component. The regulator is thus capable of responding to change in cavity air pressure by opening and closing. The regulator  68 A opens to direct air through the block  40 A to the pumping tube  30  (not shown) whenever cavity air pressure is low and closes to preclude transmission of air to the tube  30  whenever cavity air pressure is at or above desired level. Should cavity air pressure exceed an upper threshold, pressurized air may be vented through relief valve to atmosphere. 
     From  FIG. 23 , it will further be appreciated that the conventional primary input valve housed within the end  101  of the valve stem  100  may be activated and operated in conventional manner to admit air into the valve stem air chamber  174  from an external primary pressurized air source (not shown). The primary external air source thus shares the air chamber  174  within the valve stem  100  with the pumping tube pressurized air source. Such system redundancy affords greater reliability in effecting and maintaining desired tire inflation pressure. 
     The subject control valve assembly  58 A may be omitted if desired in a simplistic alternative embodiment of the subject invention as seen in  FIGS. 9B, 11B . As discussed above, the regulator  58 A limits operation of the pumping tube by blocking the delivery of ambient, non-pressurized air to the pumping tube whenever cavity air pressure is at or above rated pressure. This feature saves the pumping tube from being in a constant active or operational mode pressurizing air and reduces fatigue within the system. Whenever ambient air to the pumping tube is not being delivered, the pumping tube enters a passive non-pumping stat. However, if desired, the delivery of air to the pumping tube may be constant by reconfiguring the system to eliminate the control valve regulator  68 A, C. As shown, the bi-directional block  40 B remains the same in routing air within parallel air paths through the block to and from the pumping tube. The cover plate  58 B is modified by the elimination of the regulator  68 A, C. An air inlet opening  206  extends through the cover plate  58 B to admit constant air flow into the distribution block recess  70 . A filter pad or layer  204  may be affixed to an underside of the cover plate  58 B to purify air admitted into the block. Input air is collected within the top recess  70  of the block. Depending on the tire rotational direction, the collected input air is drawn by the pumping tube  30  along one or the other air flow paths through the block  40 B and into the pumping tube for pressurization. This simplified configuration thus keeps the pumping tube  30  in a constant pressurization mode of operation. 
     From the foregoing, it will be appreciated that the subject invention provides a conventional valve assembly mounted within a tire valve stem  100  for operably controlling a flow of pressurized air from a conventional external pressurized air source, such as a service station pump, into the tire cavity. Air pressure within the tire cavity may thus be restored manually in a conventional manner. In addition and ancillary to the manual restoration of tire air pressure, the tire-mounted air pumping tube  30  is mounted within a tire sidewall to provide an ancillary pressurized maintenance air supply into the tire cavity  28  to maintain air pressure. The duality of pressurized air sources into the tire cavity affords a redundant means by which the tire can retain proper inflation. The control assembly  14 , combining the control regulator  68 A and the bi-directional air distribution block  40 A, is positioned at a control location in proximal relationship to the valve stem  100  operative to control the flow of tire-generated pressurized air from the tire-mounted air pumping tube  30  responsive to a detected air pressure level within the tire cavity  28 . 
     The pressure control regulator  68 A, C operably controls pressurized air flow from the pumping tube by controlling the flow of ambient non-pressurized air to the tire-mounted tube. Ambient air flow is blocked by the regulator  68 A, C whenever tire air pressure does not require an increase. 
     It will further be noted that the valve stem  100  is sized and configured to extend through a rim body  16  and through the control system  14 . The integral receipt of the valve stem  100  through the block  40 A and the regulator  68 A forming the control assembly mechanically integrates the system with the valve stem and allows the external and tire-based pumping systems to share the internal passageway and air collection chamber  174  of the valve stem  100 . The pressure control assembly (regulator  68 A and block  40 A) mounts to a surface of the rim body at the control location in proximal relationship with the valve stem  100  and receives the valve stem therethrough. The bulk and geometric size of the regulator  68 A and block  40 A is accordingly not carried by the tire at the inlet and outlet ports to the pumping tube  30 . The problem of mounting and maintaining a regulator and distribution block to the tire throughout tire use is thereby avoided. The mounting location of regulator  68 A and block  40 A in a proximal relationship with the valve stem  100  and directly to the rim  14  promotes structural integrity and minimizes inadvertent separation of such components through tire use. In addition, the components  68 A,  40 A, and the filter element  69  may be accessed, repaired and/or replaced if that becomes necessary during the course of tire operation. 
     The air pumping tube  30  mounts as described within a flexing region of a tire sidewall. So located, the tube  30  closes and opens segment by segment in reaction to induced forces from the tire flexing region as the flexing region of the tire wall rotates opposite a rolling tire footprint. The circular configuration of the air pumping tube and the operation of the bi-directional air distribution block  40 A, B provides for air pumping to the tire cavity in both forward and reversed direction of tire rotation against a ground surface. Air pressure maintenance is accordingly continuous irrespective of tire rotational direction. 
     The advantages of the subject invention is that the rim valve stem  100  functions as designed to fill air into the tire with the use of a standard external device. The air passageway  174  at the bottom of the valve stem allows the pumped air into the valve stem air passageway and then the tire cavity and also provides a portal air pressure sensing by the regulator  68 A, C. The set pressure is easily adjusted by screw adjustment to the control regulator  68 A, C without dismounting the tire. The filter  69  and the regulator  68 A, C in its entirety may be easily replaced if needed. Moreover, no passageway holes on the tire sidewall is needed to interconnect the pumping tube  30  to the pressure regulator assembly  14 . 
     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.