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 
       [0001]    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 
       [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 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 
       [0003]    The invention provides in a first aspect a self-inflating tire assembly which includes 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 first end and a second end, the air passageway being composed of a flexible material operative to open and close when the tire rotates, wherein the first end and second end is in fluid communication with the tire cavity; a regulator device having a regulator body having an interior chamber; a pressure membrane being mounted on the regulator device to enclose the interior chamber, wherein the pressure membrane has a lower surface that is 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 has a first, second and third flexible duct, wherein said first, second and third flexible ducts each have an internal passageway; wherein the third flexible duct has a first end in fluid communication with the outside air, and a second end in fluid communication with the interior chamber of the regulator device, wherein the first flexible duct has a first end in fluid communication with the first end of the air passageway, and a second end in fluid communication with the interior chamber of the regulator device; wherein the second flexible duct has a first end in fluid communication with the second end of the air passageway, and a second end in fluid communication with the interior chamber of the regulator device. 
       DEFINITIONS 
       [0004]    “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. 
         [0005]    “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
         [0006]    “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
         [0007]    “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. 
         [0008]    “Circumferential” means lines or directions extending along the perimeter of a surface, perpendicular to the axial direction. 
         [0009]    “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
         [0010]    “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. 
         [0011]    “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. 
         [0012]    “Lateral” means an axial direction. 
         [0013]    “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. 
         [0014]    “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. 
         [0015]    “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. 
         [0016]    “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. 
         [0017]    “Peristaltic” means operating by means of wave-like contractions that propel contained matter, such as air, along tubular pathways. 
         [0018]    “Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire. 
         [0019]    “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. 
         [0020]    “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. 
         [0021]    “Tread element” or “traction element” means a rib or a block element defined by having shape adjacent grooves. 
         [0022]    “Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The invention will be described by way of example and with reference to the accompanying drawings in which: 
           [0024]      FIG. 1  is an isometric view of tire and rim assembly showing a pump and regulator assembly. 
           [0025]      FIG. 2A  is a schematic of the pump and regulator assembly of  FIG. 1 . 
           [0026]      FIG. 2B  is a front view of the tire of  FIG. 1  showing the system in operation. 
           [0027]      FIG. 3  is a partial front view of the pump and regulator assembly as shown from inside the tire of  FIG. 1 . 
           [0028]      FIG. 4  is an exploded view of the regulator assembly. 
           [0029]      FIG. 5  is a top view of the regulator assembly of  FIG. 4 . 
           [0030]      FIG. 6A  is a section view of  FIG. 5  in the direction  6 - 6  showing the regulator in the closed position during operation. 
           [0031]      FIG. 6B  is a section view of  FIG. 5  in the direction  6 - 6  showing the regulator in the open position during operation. 
           [0032]      FIGS. 7A-7D  are section views of  FIG. 5  in the direction  7 - 7  showing the sequence of events as flow travels through the system regulator during operation when the tire is rotating in a clockwise direction. 
           [0033]      FIGS. 8A-8D  are section views of  FIG. 5  in the direction  7 - 7  showing the sequence of events as flow travels through the system regulator during operation when the tire is rotating in a counterclockwise direction. 
           [0034]      FIG. 9A  is a cross-sectional view of a second embodiment of a double valve. 
           [0035]      FIG. 9B  is an exploded front view of the second embodiment of the double valve shown in  FIG. 9A . 
           [0036]      FIGS. 10A-10D  are section views of  FIG. 5  in the direction  7 - 7  showing the sequence of events as flow travels through the system regulator with the second embodiment of the double valve, during operation when the tire is rotating in a clockwise direction. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    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. 1-3 , the pump assembly  14  is preferably mounted into the sidewall area  15  of the tire, preferably near the bead region. 
       Pump Assembly  14   
       [0038]    The pump assembly  14  includes an air passageway  43  which may be molded into the sidewall of the tire during vulcanization or formed post cure. The air passageway may be molded into shape by the insertion of a removable strip that forms the passageway when removed. The passageway  43  acts as a pump. The air passageway  43  is preferably molded into the tire sidewall as shown in  FIG. 2 , and has an arc length as measured by a respective angle γ relative to the tire rotational axis in the range of at least 330 degrees, and more preferably in the range of about 330-380 degrees. The pump air passageway  43  may also be formed of a discrete tube 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. 
         [0039]    As shown in  FIG. 2A , an inlet filter assembly  400  is connected to a regulator device  300  for providing inlet filtered air to the regulator device  300 . 
       Regulator Device 
       [0040]    The regulator device  300  is shown in  FIGS. 2-8 . The regulator device  300  functions to regulate the flow of air to the air passageway  43 . 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 . 
         [0041]    The pressure membrane has an upper surface  551  that is substantially planar. The pressure membrane has a lower surface  553  wherein a plug  555  extends from the lower surface. The pressure membrane further has an annular sidewall  556  which extends downwardly from the upper surface, forming a lip  557 . The lip  557  is preferably annular, and snaps in an annular slot  559  formed on the outer regulator housing  310 . The pressure membrane is a disk shaped member made of a flexible material such as, but not limited to, rubber, elastomer, plastic or silicone. A lid  600  is received over the pressure membrane. The lid  600  has a plurality of holes  603  to allow the outer surface  551  of the pressure membrane to be in fluid communication with the pressure of the tire chamber  40 . The lower surface  553  of the pressure membrane is in fluid communication with the interior chamber  320 . The plug  555  is positioned to close the outlet port  330 . A spring  580  is positioned in the interior chamber  320  to bias the pressure membrane  550  in the open position. The spring has a first end  582  that is received about the plug  555 . The spring has a second end  584  that is wrapped around the outer surface of the outlet port  330 . A first washer  586  may be received between the spring first end  582  and the pressure membrane  550 . A second washer  588  may be received between the spring second end  584  and the bottom of the chamber  313 . The lid  600  is made of a rigid material, and resists the spring force, thus functioning to preload the spring via the pressure membrane  550 . Thus the balance of pressure forces on each side of the pressure membrane actuates the pressure membrane plug  555  to open and close the outlet port  330 . 
         [0042]    Extending from the central regulator housing  310  is a first, second and third flexible duct  350 ,  360 ,  370  positioned on either side of the central regulator housing  310 . Each flexible duct  350 ,  360 ,  370  may be integrally formed with the regulator housing as shown, or be a discrete part connected to the central regulator housing  310 . Each flexible duct  350 ,  360 ,  370  has an internal passageway  352 ,  362 ,  372  for communicating fluid. 
         [0043]    As shown in  FIG. 7A , the internal passageway  352  of the first flexible duct  350  has a first end  354  that is connected to the outlet port  330 . The internal passageway  352  of the first flexible duct  350  has a second end  356  that is in fluid communication with a first valve  100 . The second end terminates in a circular flange  358  that is received about the outer body of the first valve  100 . The first valve  100  is connected to the first end  42  of the pump passageway  43 . 
         [0044]    As shown in  FIG. 7A , the second flexible duct  360  has an internal passageway  362  having a first end  361  that is connected to the outlet port  330  of the interior chamber  320  and the internal passageway  352  of the first flexible duct  350 . The internal passageway  362  has a second end  364  in fluid communication with a second valve  100 . The second flexible duct has a circular flange distal end  368  that is received about the outer body of the second valve  100 . 
         [0045]    As shown in  FIGS. 5 and 6A , the third flexible duct  370  connects an inlet filter assembly  400  to the internal chamber  320  of the pressure regulator  300 . The internal passageway  372  of the third flexible duct  370  has an outlet  374  that is connected to the outlet port  442  of the inlet filter assembly  400 . The distal end of the third flexible duct terminates in a circular flange  373  that is received about the outer body of the inlet filter assembly  400 . The internal passageway  372  of the first flexible duct  370  has a second end  376  that opens to the inlet chamber  320  of the regulator  300 . 
       Inlet Filter Assembly 
       [0046]    The inlet filter assembly  400  is shown in  FIGS. 6A ,  6 B. The inlet filter assembly  400  includes an insert sleeve  412  that is hollow and has an internal threaded bore  414  that extends completely therethrough. The insert sleeve  412  has a first end that is inserted into the tire, typically in the outer surface of the sidewall  15 . The insert sleeve  412  may be inserted into the tire post cure or may be molded into the tire. The insert sleeve first end has an enlarged bore  424  for receiving the threaded end of an air passage screw  420 . The insert sleeve has a second end that is positioned on the outer surface of the tire to provide ambient air to the internal bore  414 . The air passage screw  420  has an internal passageway  430  having an opening  432  in fluid communication with the bore  414  of the insert sleeve  412 . A filter  440  is received within the insert sleeve  412  near the inlet end. The internal passageway  430  of the air passage screw  420  has outlet holes  442  in fluid communication with the inlet  374  of the internal passageway  372  of the third flexible duct  370 . 
       Inlet/Outlet Valve 
       [0047]    The first end  42  of the pump passageway  43  is connected to a first valve  100 . The second end  44  of the pump passageway  43  is connected to a second valve  100 . The first and second valves  100  are shown as structurally the same, although one or both of the valves could be as valve  200  shown in  FIG. 9A . The first and second valve  100  is shown in operation in  FIGS. 7A-D . The valve  100  includes a valve body  110  having an upper valve  111 , and a lower valve  114 . The upper valve  111  communicates pumped air from the pump to the tire cavity, and the lower valve communicates flow from the regulator to the pump. The lower valve  114  has a first end  112  having an outer threaded surface  113  that is mounted within the sidewall of the tire. The valve body  110  has a central passage  115  that extends substantially through the valve body  110 , i.e., the central passage connects the upper valve  111  to the lower valve  114 . 
         [0048]    The lower valve  114  has a first end of the central passage  115  having an enlarged opening  118  that is in fluid communication with the pump passageway  43  first end  42 . A cylindrical support member  120  is received in the enlarged opening  118  of the central passage  115 . The cylindrical support member  120  has a bore  122  that extends therethrough. A flexible collar  124  is received about the cylindrical support member  120 . The outer end of the flexible collar  124  is positioned to open and close holes  126  to communicate flow from the first flexible duct passageway  352  to the passage  115  and then to the pump passageway  42 , or from the pump passageway  42 , through the valve body passage  115  to the flexible duct passageway. Thus the valve  100  works when the flow is traveling in either direction.  FIG. 7A  illustrates flow from the regulator  300  traveling through the first flexible duct towards the lower valve  114 . As shown in  FIG. 7   b , the pressure from the flow partially folds the flexible collar  124  so that the fluid enters central passage  115 . The flow travels through the central bore  122  and into the pump. As shown in  FIG. 7C , the flow travels through the 360 degree pump and to the second end  44  of the pump. The flow enters the lower end of the double valve  100  through the bore  122 ′ of the cylindrical support member  120  and then through the central passage  115 ′. 
         [0049]    The central passage  115  has a second end  117  that terminates in the upper valve  111  into a transverse passage  119 . The transverse passage  119  is perpendicular to the central passage  115 , forming a T shaped passage. A second flexible sleeve  130  is mounted to the valve body  110  and is positioned to open and close the outlet holes  128  of the transverse passage  119 . 
         [0050]      FIGS. 7C and 7D  illustrate the upper valve in action. Pumped air exits the pump outlet end  44 , and travels through the lower valve  114 . The sleeve  124  prevents the flow from exiting the valve. The flow travels to the upper valve  111  through central passage  115 . The second flexible sleeve  130  opens to release the flow into the tire cavity  40  as shown in  FIG. 7D . The operation of flow through the valves depends on the direction of the tire rotation.  FIGS. 7A-7D  illustrate the system in operation for clockwise tire rotation, while  FIGS. 8A-8D  illustrate the system in operations for counterclockwise tire rotation. As shown in the Figures, each valve  100  can port flow from the pump outlet to the tire cavity via the upper valve  111 , or port flow from the regulator to the pump inlet via the lower valve  114 . 
         [0051]    A second embodiment  200  of a double valve is shown in  FIG. 9A  and  FIG. 9B . The double valve  200  includes a valve body  210  having an upper valve  211 , and a lower valve  214 . The upper valve  211  communicates pumped air from the pump to the tire cavity through a passage  215 , and the lower valve communicates flow from the regulator to the pump through the passage  215 . 
         [0052]    The valve body  210  has a first end  212  having an outer threaded surface  213  that is mounted within the sidewall of the tire. The lower valve  214  is inserted into a transverse passage  217  that intersects passage  215 . The lower valve  214  is a check valve, preferably a duckbill check valve as shown. The duckbill check valve has elastomeric lips  217  in the shape of a duckbill which prevents backflow and allows forward flow from the inlet  219  to the passage  215 . The flow exits the duckbill elastomeric lips into the passage  215 . The lower valve  214  could also be other types of check valves known to those skilled in the art, such as ball valves, etc.  FIG. 10  illustrates flow from the regulator into the flexible duct, and into the angled passage  240  to the inlet  219  of the duckbill check valve. The flow exits the check valve through the lips  217  into the passage  215  and then to the pump inlet. 
         [0053]    The upper valve  211  is a sleeve type check valve, having an outer annular flexible sleeve  232  that opens and closes over outlet holes  234  of outlet passageway  230 . Outlet passageway  230  is in fluid communication with passage  215 .  FIGS. 12 and 13  illustrate the upper valve during operation, when flow from the pump is directed through the passage  215 , past the duckbill lips  217  which block entry to the lower valve  214 , and to outlet passageway  230  through the sleeve and into the tire cavity. 
       System Operation 
       [0054]      FIGS. 1-2  illustrate a 360 degree pump assembly  14 . The system is bidirectional, so that the pump can pump in either direction of rotation. As shown in  FIGS. 2A and 2B , the regulator device  300  is in fluid communication with the first end  42  of the pump passageway  43 . As the tire rotates in the clockwise direction as shown in  FIG. 2B , 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 . Successive flattening of the pump passageway  43  as the tire rotates and forces the compressed air towards the pump outlet in a direction opposition the direction of rotation of the tire. Due to the increase in pressure at the pump outlet  44 , the double valve  100  directs the flow through the valve central passage and into the tire cavity  40 . 
         [0055]    The regulator device  300  controls the inflow of outside air into the pump. If the tire pressure is above the preset threshold value, the plug  555  of the pressure membrane seals the central outlet port  330  and no air enters the pump passageway, as shown in  FIG. 6A . The pressure preset threshold value can be predetermined based upon the tire size, and the material properties of the pressure membrane, and spring constant can be selected to determine the pressure at the preset threshold value. If the tire pressure falls below the preset threshold value, the plug  555  of the membrane  550  will unseat from the central outlet port  330 , opening the outlet port  330  as shown in  FIG. 6B . As the chamber pressure  320  falls due to the opening of the central outlet port  330 , outside air will be sucked through the filter  440 , through the central passageway  430 , through the third flexible duct  372  to the interior chamber  320 . If the tire rotates in a clockwise direction, the filtered air exits the interior chamber through the outlet port  330 , and enters the passageway  352  of the first flexible duct  350 . Then the filtered air passes through the double valve  100  into the lower valve  114  and then into the pump inlet  42 , as shown in  FIGS. 7A and 7B . The flow is then compressed through the pump passageway  43  and then enters the double valve  100 , as shown in  FIG. 7C . The flow travels through the lower valve through the central passage  115 ′ into the upper valve  111 . The flow exits the upper valve into the tire cavity  40  via the sleeve  130  which opens under the pressure of the flow. 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. 
         [0056]    If the tire rotates in a counterclockwise direction, the operation of the system is shown in  FIGS. 8A-8D . The filtered air exits the interior chamber  320  through the outlet port  330 , and enters the second flexible duct  360  then through the lower valve  114  of the double valve  100  and then into the pump inlet  44 . The flow is then compressed through the pump passageway  43  to the pump outlet  42 . As shown in  FIGS. 8C and 8D , the flow exits the upper valve  111 ′ into the tire cavity  40 . 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. 
         [0057]    The location of the pump assembly in the tire will be understood from  FIGS. 1 ,  2 A and  3 . In one embodiment, the pump assembly  14  is positioned in the tire sidewall, radially outward of the rim flange surface. 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 region 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 or any desired shape. 
         [0058]    The length as represented by the angle Ψ of each pump passageway is illustrated at about 350-360 degrees, the invention is not limited to same, and may be shorter or longer as desired. 
         [0059]    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. 
         [0060]    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.