Abstract:
A self-inflating tire assembly includes an air tube connected to a tire and defining an air passageway, the air tube being composed of a flexible material operative to allow an air tube segment opposite a tire footprint to flatten, closing the passageway, and resiliently unflatten into an original configuration. The air tube is sequentially flattened by the tire footprint in a direction opposite to a tire direction of rotation to pump air along the passageway to a regulator device. The regulator device regulates the inlet air flow to the air tube and the outlet air flow to the tire cavity.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to self-inflating tires and, more specifically, to a pump mechanism and pressure regulator for such tires. 
     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 dependant upon the driver taking remedial action when warned to re-inflate a tire to recommended pressure. It is a desirable, therefore, to incorporate a self-inflating feature within a tire that will self-inflate the tire in order to compensate for any reduction in tire pressure over time without the need for driver intervention. 
     SUMMARY OF THE INVENTION 
     The invention provides a self-inflating tire assembly including a tire mounted to a rim, the tire having a tire cavity, first and second sidewalls extending respectively from first and second tire bead regions to a tire tread region; an air passageway having an inlet end and an outlet end, the air passageway being composed of a flexible material operative to open and close when the tire rotates, wherein the inlet end is connected to an outlet port of a regulator device, and the outlet end is in fluid communication with the tire cavity; the regulator device having a regulator body having an interior chamber; a pressure membrane is mounted in the interior chamber and positioned to open and close the outlet port mounted in the interior chamber, wherein the pressure membrane is in fluid communication with the tire cavity pressure wherein the body of the regulator device is connected to a first flexible duct having an internal passageway; wherein the first flexible duct has a first end connected to an inlet filter assembly, wherein the inlet filter assembly is in fluid communication with the outside air supply; wherein a second end of the first flexible duct is connected to an opening of the interior chamber of the regulator device. 
     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 a surface, perpendicular to the axial direction. 
     “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. 
     “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. 
     “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. 
     “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 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 an isometric view of tire and rim assembly showing a pump and regulator assembly. 
         FIG. 2  is a front view of the pump and regulator assembly as shown from inside the tire of  FIG. 1 . 
         FIG. 3  is an exploded view of the pump and regulator assembly of  FIG. 2 . 
         FIG. 4  is the perspective view of the air passage screw; 
         FIG. 5  is a section view in the direction 5-5 of  FIG. 4 ; 
         FIG. 6  is a perspective view of the sleeve insert; 
         FIG. 7  is a section view in the direction 7-7 of the sleeve insert of  FIG. 6 ; 
         FIG. 8  is a perspective view of the filter cap; 
         FIG. 9  is a perspective view of the top portion of the filter cap of  FIG. 8 ; 
         FIG. 10  is a section view in the direction 10-10 of  FIG. 8 ; 
         FIG. 11  is a perspective view of the filter; 
         FIG. 12  is a section view in the direction 12-12 of  FIG. 11 ; 
         FIG. 13  is a perspective view of a regulator membrane; 
         FIG. 14  is a section view of the regulator membrane of  FIG. 13  in the direction 14-14; 
         FIG. 15  is a perspective view of a regulator body; 
         FIG. 16  is a section view of the regulator body in the direction 16-16 of  FIG. 15 ; 
         FIG. 17  is a perspective view of a valve body for the inlet valve; 
         FIG. 18  is a cross-sectional view of the valve body of  FIG. 17  in the direction 18-18; 
         FIG. 19  is a perspective view of the inlet valve; 
         FIG. 20  is a section view of the inlet valve of  FIG. 19  in the direction 20-20; 
         FIG. 21  is a perspective view of the inlet valve insert; 
         FIG. 22  is a cross-sectional view of the inlet valve insert of  FIG. 21 ; 
         FIG. 23  is a perspective view of the outlet valve support; 
         FIG. 24  is a cross-sectional view of the outlet valve support of  FIG. 23  in the direction 24-24; 
         FIG. 25  is a perspective view of the flexible stopper; 
         FIG. 26  is a section view of the flexible stopper of  FIG. 25  in the direction 26-26; 
         FIG. 27  is a perspective view of the permanent valve insert; 
         FIG. 28  is a section view of the valve insert of  FIG. 27 ; 
         FIG. 29  is a section view of  FIG. 2  in the direction 29-29 showing the regulator in the closed position. 
         FIG. 30  is a section view of  FIG. 2  in the direction 29-29 showing the regulator in the open position and the inlet control valve in the open position 
         FIGS. 31  A-C illustrate the inlet control valve in the open position and closed position. 
         FIGS. 32  A-C illustrate the outlet control valve in the closed position (A) and the open position (B-C). 
         FIG. 33  is a partial view of the inside of the tire during operation, shown with the sidewall removed for clarity reasons. 
         FIG. 34  is a partial view of a tire showing the sidewall cross-section and the air passageway. 
         FIG. 35  illustrates a front view of a tire with a 180 degree pump shown in phantom. 
         FIG. 36  illustrates a front view of a tire with a 340 degree pump shown in phantom. 
         FIG. 37  illustrates a front view of a tire shown with a 730 degree pump shown in phantom. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , a tire assembly  10  includes a tire  12 , a pump assembly  14 , and a tire rim  16 . The tire and rim enclose a tire cavity  40 . As shown in  FIGS. 1-2 , the pump assembly  14  is preferably mounted into the sidewall area  15  of the tire, preferably near the bead region. 
     Pump Assembly  14   
     The pump assembly  14  includes an air passageway  43  which may be molded into the sidewall of the tire during vulcanization or molded post cure. The air passageway has a length L that may extend in a circumferential direction, or any direction. The length L may range, and is preferably about the length of the tire footprint Z, as shown in  FIG. 33 . The length is typically about 20-40 degrees when the shorter length is used. Alternatively, the pump tube length may be any desired length, typically 20 degrees or more.  FIG. 35  illustrates a pump tube length of about 180 degrees.  FIG. 36  illustrates a pump tube length of about 340 degrees, and  FIG. 36  illustrates a pump tube length of about 730 degrees. The pump air passageway  43  is comprised of a tube body formed of a resilient, flexible material such as plastic, elastomer or rubber compounds, and is capable of withstanding repeated deformation cycles when the tube is deformed 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 tube is of a diameter sufficient to operatively pass a volume of air sufficient for the purposes described herein and allowing a positioning of the tube in an operable location within the tire assembly as will be described. Preferably, the tube has a circular cross-sectional shape, although other shapes such as elliptical may be utilized. The tube may be a discrete tube that is inserted into the tire during tire manufacturing, or the tube may be molded into shape by the presence of a removable strip that forms the passageway when removed. 
     The pump passageway  43  has an inlet end  42  connected to an inlet valve  100 , and an outlet end  44  that is connected to an outlet valve  200 . The inlet valve  100  is in fluid communication with a regulator device  300 . The regulator device  300  is in fluid communication with an inlet filter assembly  450 . 
     Regulator Device 
     The regulator device  300  is shown in  FIGS. 13-16  and  FIGS. 29-30 . The regulator device  300  functions to regulate the flow of air to the pump  14 . The regulator device  300  has a central regulator housing  310  that houses an interior chamber  320 . The interior chamber  320  has a central opening  312 . Opposite the central opening  312  is an outlet port  330 . The outlet port is raised from the bottom surface  313  and extends into the interior of the chamber  320 . The outlet port is positioned to engage a pressure membrane  550 . The pressure membrane  550  is positioned within a recessed slot  340  formed in the sidewall  315  of the interior chamber  320 . The pressure membrane is a disk shaped member made of a flexible material such as, but not limited to, rubber, elastomer, plastic or silicone. The pressure membrane is operable to open and close the outlet port  330 . The outer surface  551  of the pressure membrane is in fluid communication with the pressure of the tire chamber  40  via central opening  312 . The lower surface  553  of the pressure membrane is in fluid communication with the inlet air supplied from the inlet device  450 , as described in more detail, below. Thus the balance of pressure forces on each side of the pressure membrane actuates the pressure membrane to open and close the outlet port  330 . 
     Extending from the central regulator housing  310  is a first and second flexible duct  400 ,  500 , positioned on either side of the central regulator housing  310 . Each flexible duct  400 , 500  may be integrally formed with the regulator housing, or be a discrete part connected to the central regulator housing  310 . Each flexible duct  400 ,  500  has an internal passageway  404 ,  504  for communicating fluid. 
     The internal passageway  404  of the first flexible duct  400  has a first end  402  that is in fluid communication with an opening  322  to the interior chamber  320 . The internal passageway  404  of the first flexible duct  400  has a second end  406  that is in fluid communication with an inlet filter assembly  450 . The inlet device  450  supplies outside filtered air to the regulator via the first flexible duct  400 , and is described in more detail below. 
     The internal passageway  504  of the second flexible duct  500  has a first end  502  that is in fluid communication with the outlet port  330  of the interior chamber  320 . The internal passageway  504  has a second end  506  in fluid communication with a directional valve  100 . The directional valve  100  communicates flow to the pump passageway  43  and prevents backflow of air to the regulator device  300 . 
     Inlet Filter Assembly 
     The inlet filter assembly  450  is shown in  FIGS. 2-3, and 29-30 , with its subcomponents shown in  FIGS. 4-12 . The inlet filter assembly  450  includes an insert sleeve  452  that is hollow and has an internal threaded bore  454 . The insert sleeve  452  is inserted into the tire, typically in the sidewall  15 . The insert sleeve  452  may be inserted into the tire post cure or may be molded into the tire as shown in  FIG. 2 . An air passage screw  460  has an outer threaded body  463  that is screwed into the internal threaded bore  454  of the insert sleeve. The air passage screw  460  has an internal passageway  462  having an opening  464 . A filter  470  is inserted through opening  464  and is received in the internal passageway  462 . A filter cap  480  has a threaded end  482  that is received in the opening  464  of the air passage screw  460 . The filter cap is positioned on the outside surface of the tire, typically on the tire sidewall as shown in  FIG. 1 . The filter cap has a plurality of holes  484  for allowing the flow of air into the inlet filter  470 . Outside air enters hole  484  and then through filter cap passageway  486  and then into and through filter  470 . The filter air exits the filter  470  into the internal passageway  462  of the air passage screw  460 . The air exits the internal passageway  462  through exit hole  490  and then into the inlet end of the first flexible duct  400 . The distal end of the flexible duct  400  has a circular flange  495  surrounding a hole  410  through which the air passage screw is inserted. The exit hole  490  is located in a circumferential groove  491  to facilitate fluid communication with inlet hole  406  of the first flexible duct  400 . The circular flange  495  functions like a sealing gasket if it is made of a flexible soft material like rubber. 
     Pump Inlet check valve 
     A pump inlet check valve  100  that communicates with the regulator  300  is shown in  FIGS. 29-31  and in  FIGS. 17-22 . The pump inlet check valve  100  includes an insert sleeve  102  that is inserted into the tire on an interior surface, typically the inner sidewall as shown in  FIG. 3 . The insert sleeve  102  has an internal threaded bore  104 . The insert sleeve  102  may be molded into the tire  12  or inserted post cure. The insert is installed in the tire area so that the internal bore  104  is in fluid communication with an inlet end  42  of the pump passageway  43 . A valve body  110  has an outer threaded surface  112  that is received within insert  102 . The valve body  110  has a central passage  115  that has a first opening  118  that is in fluid communication with the insert sleeve bore  104  and the pump passageway  43  inlet end  42  when inserted into the tire. The central passage  115  has two opposed holes  120  located in a circumferential groove  121  near the head  122  of the valve body  110 . The head  122  has a shaped head bore  124  such as a hexagonal head for receiving a mating tool such as an allen wrench, useful for tightening the valve body  110  inside the sleeve  102 . The central passage  115  further includes a retainer slot  130  for receiving flexible stopper  140 . The flexible stopper  140  is preferably made of a resilient material such as rubber, silicone, or an elastomer. The flexible stopper  140  has a disk shaped lower end  142 , and two opposed legs  144  which extend from the lower end  142 . Each leg  144  has a shoe  150  which has a curved enlarged shape and is made of a resilient material. As shown, the shoe is a semi-circle, although other shapes would work for the invention. Although the flexible stopper  140  is shown with two legs  144 , the stopper could have a single leg  144  with a shoe thereon, and the shoe could be annular with holes that allow passage of air therethrough. 
     The pump inlet check valve  100  may also be other types of check valves such as ball spring valves, duckbill, as known to those skilled in the art. 
     The disk shaped lower end  142  of the flexible stopper is seated on the valve body distal end and the legs  144  extend into the passage  115 . Each shoe  150  is received in the annular retainer slot  130 . The disk lower end  142  is positioned to seal the opening  118  of the central passage  115 . 
       FIGS. 31A-C  illustrate the pump inlet check valve  100  installed and operational.  FIG. 31A  illustrates flow from the regulator, through the pump inlet check valve  100  and to the pump inlet  42 . The disk lower end  142  of the flexible stopper  140  does not seal the central passage  115  when the flow direction is towards the pump  43 .  FIG. 31B  illustrates the disk lower end  142  of the flexible stopper  140  sealing the central passage  115  so that no flow travels in the reverse direction from the pump to the regulator.  FIG. 31C  illustrates the disk lower end  142  of the flexible stopper  140  sealing the central passage  115  as the valve is being cracked open upon flow reversal. 
     Pump Outlet Check Valve 
     As described above, a first end  42  of the pump is connected to a regulator and a check valve. The second end  44  of the pump is connected to a pump outlet valve  200 . The pump outlet valve is shown in  FIGS. 29-30, 32  and in  FIGS. 23-28 . The pump outlet valve  200  includes an insert sleeve  202  that is inserted into the tire on an interior surface, typically the inner sidewall as shown in  FIG. 3 . The insert sleeve  202  has an internal threaded bore  204 . The insert sleeve  202  may be molded into the tire  12  or inserted post cure. The insert is installed in the tire area so that the internal bore  204  is in fluid communication with the pump outlet end  44 . A valve body  210  has an outer threaded surface  212  that is received within insert  202 . The valve body  210  has a central passage  215  that has a first opening  218  that is in fluid communication with the insert sleeve bore  204  and the pump passageway  43  outlet end  44  when inserted into the tire. The central passage  215  has an outlet end  217  that is in fluid communication with the tire cavity. The valve body has a shaped head  222  such as a hexagonal shaped head bore  224  for receiving a mating tool such as an allen wrench useful for tightening the valve body  210  inside the sleeve  202 . The central passage  215  further includes a retainer slot  230  for receiving flexible stopper  240 . The flexible stopper  240  is preferably made of a resilient material such as rubber, silicone, or an elastomer. The flexible stopper  240  has a disk shaped lower end  242 , and two opposed legs  244  which extend from the lower end  242 . Each leg  244  has a shoe  250  which has a curved enlarged shape and is made of a resilient material. As shown, the shoe is a semi-circle, although other shapes would work for the invention. Although the flexible stopper  240  is shown with two legs  244 , the stopper could have a single leg  244  with a shoe thereon, and the shoe could be annular with holes that allow passage of air therethrough. 
     The flexible stopper is mounted inside the central passage so that each shoe  250  of the flexible stopper is received in the annular retainer slot  230 , and the disk lower end  242  is positioned to open and close the pump end  44 . 
       FIGS. 32A-C  illustrate the pump outlet valve  200  installed and operational.  FIG. 32C  illustrates flow from the pump outlet  44  to the pump outlet valve  200 . The disk lower end  242  of the flexible stopper  240  does not seal the pump outlet  44  when the flow direction is towards the pump outlet valve  200 . The flow travels through the central passage  215 , around and through the legs  244  and exits the passage outlet  217  to the tire cavity.  FIG. 32A  illustrates the disk lower end  142  of the flexible stopper  140  sealing the pump end  44  so that flow is blocked from flowing to the cavity. This occurs when the pump is not pumping. FIG.  32 B illustrates the disk lower end  142  of the flexible stopper  140  being lifted by the valve cracking pressure when the pump starts pumping. 
     System Operation 
     As will be appreciated from  FIG. 33 , the regulator device  300  is in fluid communication with the inlet end of the pump passageway  43 . As the tire rotates, a footprint is formed against the ground surface. A compressive force F is directed into the tire from the footprint and acts to flatten the pump passageway  43 . Flattening of the pump passageway  43  forces the pumped air towards the pump outlet device  200 . Any flow that is directed towards the regulator  300  is blocked from entering the regulator by the pump inlet check valve  100  as shown in  FIG. 31B . Due to the increase in pressure at the pump outlet  44 , the pressure unseats the disk  242  from the opening of the pump outlet  44 , which allows the pumped air to exit the pump outlet device through passage  215  into the tire cavity  40 . 
     The regulator device  300  controls the inflow of outside air into the pump. If the tire pressure is low, the membrane  550  in the regulator device  300  is responsive to the tire pressure in the tire cavity  40 . If the cavity pressure falls below a preset threshold value, the membrane will unseat from the central outlet port  330 . Outside air will enter the filter assembly  450 , exit through the filter and enter the first flexible duct  400 . The flow then exits the first flexible duct and enters the regulator chamber and then into the second flexible duct, through the regulator check valve, and then into the pump inlet. The flow is then compressed through the pump and then exits the pump outlet valve into the tire cavity. The pump will pump air with each tire rotation. The pump passageway  43  fills with air when the pump system is not in the footprint. 
     If the tire pressure is sufficient, the regulator device will block flow from entering the pump inlet. The pressure membrane is responsive to the cavity tire pressure and engages the central port  330  forming a seal which prevents air flow from passing through the regulator device. The pressure membrane material properties are adjusted to have the desired tire pressure settings. 
     The location of the pump assembly in the tire will be understood from  FIGS. 1 and 34 . In one embodiment, the pump assembly  14  is positioned in the tire sidewall, radially outward of the rim flange surface in the chafer  600 . So positioned, the air passageway  43  is radially inward from the tire footprint and is thus positioned to be flattened by forces directed from the tire footprint as described above. Although the positioning of the air passageway  43  is specifically shown in a chafer  600  of the tire near the bead region, it is not limited to same, and may be located at any region of the tire that undergoes cyclical compression. The cross-sectional shape of the air passageway  43  may be elliptical or round. 
     As described above, the length L of the pump passageway may be about the size of the tire&#39;s footprint length Z. However, the invention is not limited to same, and may be shorter or longer as desired. See  FIG. 35  which illustrates an approximate 180 degree length,  FIG. 36  which illustrates an approximate 340 degree length, and  FIG. 37  which illustrates a 730 degree length. As the length of the pump increases, the pump passageway will need to substantially open and close like a peristaltic pump. 
     The pump assembly  14  may also be used with a secondary tire pressure monitoring system (TPMS) (not shown) of conventional configuration that serves as a system fault detector. The TPMS may be used to detect any fault in the self-inflation system of the tire assembly and alert the user of such a condition. 
     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.