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 dependant 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. It is also desired to provide a valve system in order to regulate the tire pressure. 
       SUMMARY OF THE INVENTION 
       [0003]    The invention provides in a first aspect 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, a regulator device, the regulator device including a regulator body, wherein the regulator body has an interior chamber; a pressure membrane being mounted in the interior chamber and positioned to open and close an outlet port mounted in the chamber, wherein the pressure membrane is in fluid communication with the tire cavity pressure; wherein the outlet port of the regulator device is in fluid communication with the inlet end of the air passageway; said interior chamber being in fluid communication with an outside air supply; wherein the air passageway outlet end is in fluid communication with the tire cavity. 
       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 a tire and rim assembly showing a pump and an inlet regulator valve assembly. 
           [0025]      FIG. 2  is a front view of the pump and inlet regulator valve assembly as shown from inside the tire of  FIG. 1 . 
           [0026]      FIG. 3  is an exploded view of the inlet regulator valve assembly of  FIG. 2 . 
           [0027]      FIG. 4  is an exploded view of the inlet regulator valve assembly of  FIG. 3 , as viewed from below. 
           [0028]      FIG. 5  is a section view of  FIG. 2  in the direction  5 - 5  showing the inlet regulator valve assembly in operation during pumping. 
           [0029]      FIG. 6  illustrates the system of  FIG. 5  shown when the inlet regulator valve is closed. 
           [0030]      FIG. 7  illustrates the system of  FIG. 5  shown when the inlet check valve is closed. 
           [0031]      FIG. 8  is a section view showing an alternate embodiment of an inlet regulator valve assembly in operation during pumping. 
           [0032]      FIG. 9  illustrates the system of  FIG. 8  shown when the inlet regulator valve is closed. 
           [0033]      FIG. 10  illustrates the system of  FIG. 8  shown when the inlet check valve is closed. 
           [0034]      FIG. 11  illustrates the system during tire rotation. 
           [0035]      FIG. 12  is an exploded view of the outlet valve. 
           [0036]      FIG. 13A , B, C illustrates the outlet valve closed, during cracking and open, respectively. 
       
    
    
     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. 1-2 , 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 molded or formed post cure. The air passageway has an arc length L, wherein the arc length is measured by angle Ψ that is measured from the center of rotation of the tire. In a first embodiment, the angle Ψ may range, and is preferably in the range of about 15-50 degrees or optionally, an angular length sufficient to extend the length of the tire footprint Z, as shown in  FIG. 11 . The pump air passageway  43  is comprised of an inserted tube body or a passageway formed in the tire wall. For example, the tube may be molded in the tire into a desired shape by the presence of a removable strip that forms the passageway when removed. If the passageway  43  is a inserted tube body, it should be formed of a resilient, flexible material such as plastic, elastomer or rubber compounds, and be capable of withstanding repeated deformation cycles when the tube is deformed into a partially flattened condition or a completely flattened condition subject to external force and, upon removal of such force, returns to an original condition. 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 or air passageway has a circular cross-sectional shape, although other shapes such as elliptical may be utilized. Preferably, the air passageway is located inside the tire sidewall. 
         [0039]    The pump passageway  43  has an inlet end  42  connected to an optional inlet check valve  100 , and an outlet end  44  that is connected to an outlet check valve  200 . The inlet check valve  100  is in fluid communication with an inlet control valve  300 . 
       Inlet Control Valve  300   
       [0040]    The inlet control valve  300  is shown in  FIGS. 3-7 . The inlet control valve  300  functions to regulate the flow of air to the pump  14 . If the tire is determined by the inlet control valve to need additional air, the inlet control valve will allow air to enter the system. The inlet control valve  300  has a T shaped valve housing  310 . At the upper end  312  of the T shaped housing there is an interior chamber  320 . The interior chamber  320  has a central opening  314 . Opposite the central opening  314  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  330  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  314  and via the cap hole  370 . The lower surface  553  of the pressure membrane is in fluid communication with the inlet air supplied from the distal end  380  of the inlet control valve, 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 . A cap  360  is received over the upper end  312  of the valve housing  310 . The cap has an interior threaded surface  362  that is secured to the outer threaded surface  311  of the upper end of the valve housing. The cap  360  has an opening  370  that is aligned with central opening  312  so that pressure membrane is in fluid communication with the tire cavity  40 . An optional washer  361  is received between the pressure membrane and the cap. 
         [0041]    The distal end  380  of the inlet control valve housing has an outer threaded surface  382  that is received in insert sleeve  384 . The insert sleeve is preferably inserted into the tire post cure or may be molded into the tire as shown in  FIG. 5 . Preferably the insert sleeve  384  is permanently affixed in the tire sidewall  15 . A first opening  386  of the insert sleeve  384  is preferably flush with the tire outer sidewall  15 . 
         [0042]    The distal end  380  of the inlet control valve housing has an internal cavity  390  for receiving a filter  392 . A filter cap  394  has a threaded end  395  that is received in the opening  391  of the internal cavity  390 . The filter cap  394  is positioned on the outside surface of the tire, typically on the tire sidewall as shown in  FIG. 1 . The filter cap is received in the opening  391  and has a plurality of holes  396  for allowing the flow of air into the filter  392 . Outside air enters hole  396  and then proceeds through the filter  392 . As shown in  FIG. 5 , the filtered air exits the filter  392  into an internal passageway  393  that extends from the internal cavity  390  to the internal chamber  320 . 
         [0043]    If the tire pressure is lower than the target pressure, the pressure membrane  550  will not block the central opening  330  of the internal chamber  320 . Filtered air from the first internal passageway  393  may flow through central opening  330  and then into an exit channel  397  having an exit  399  that is in fluid communication with the interior channel  406  of the flexible duct. 
         [0044]    A second embodiment  700  of the inlet control valve is shown in  FIGS. 8-10 . The main difference between the second embodiment  700  and the first embodiment  300  is the channel which is plugged by the membrane. In the first embodiment, the channel plugged by the membrane is in fluid communication with the pump. In the second embodiment, the channel plugged by the membrane is coming from the filter. The inlet control valve  700  is the same as the inlet control valve  300  described above, except for the following differences. Internal passageway  393  and exit channel  397  have been eliminated. The T shaped regulator housing  310  has a central channel  710  that has a first end  712  that opens to the interior chamber  720 . The pressure membrane positioned in the interior chamber  720  is positionable over the opening  712 . A filter  392  is positioned in the channel  710  and is secured within the channel  710  with a filter cap  394 . The inlet control valve  700  further includes an exit passageway  730  that has a first end  732  that opens to the interior chamber  720 , and a second end  734  that is in fluid communication with the first end  420  of a flexible duct  400 . The passageway  730  may be annular in shape. An annular notch  736  surrounds the second end  734  of the exit passageway  734 . 
       Flexible Duct  400   
       [0045]    A flexible duct  400  has an interior channel  406  that extends to two opposed flanged ends  410 ,  412 . The interior channel  406  is useful for communicating fluid from the inlet pressure regulator to the inlet check valve  100 , or between two or more devices. Each flanged end  410 ,  412  is circular for reception about the body of the inlet control valve  300  and the body of the inlet check valve, respectively. Each flanged end  410 ,  412  has a hole therethrough  414 ,  416  respectively. The interior channel  406  has a first end  420  that terminates in the first flanged end  410 , and a second end  422  that terminates in the second flanged end  412 . The first flanged end  410  is received about the T shaped housing  310  of the inlet control valve  300 . The second flanged end  412  is received about the housing of the inlet check valve  100 . The flexible duct  400  may be integrally formed with the inlet control valve housing, or be a discrete part connected to the central housing  310 . 
       Inlet Check Valve  100   
       [0046]    An inlet check valve  100  that communicates with the inlet control valve  300  is shown in  FIGS. 3-7 . The 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. 5 . 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  near the head  122  of the valve body  110 . The head  122  has a hex head bore  124  (or any screwdriver slot shape) for receiving 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. 
         [0047]    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  as shown in  FIG. 7 . 
         [0048]      FIGS. 7-8  illustrate the regulator check valve  100  installed and operational. 
         [0049]      FIG. 8  illustrates flow from the inlet control valve  300 , through the 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. 7  illustrates the disk lower end  142  of the flexible stopper  140  sealing the passageway  115  so that no flow travels in the reverse direction from the pump to the inlet control valve  300 . 
       Pump Outlet Check Valve 
       [0050]    As described above, a first end  42  of the pump is in fluid communication with an inlet control valve  300  and a check valve  100 . The second end  44  of the pump is connected to a pump outlet valve  200 . The pump outlet valve is shown in  FIGS. 12 ,  13 A-C. The pump outlet valve  200  includes an insert sleeve  202  that is inserted into the tire on an interior surface, typically the inner sidewall. 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 head  222  having a hex head bore  224  (or any screwdriver slot shape) for receiving 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 the 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. 
         [0051]    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 . 
         [0052]      FIGS. 13A-C  illustrate the pump outlet valve  200  installed and operational.  FIG. 13C  illustrates the pump outlet valve  200  in the open position. 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. 13A  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. 13B  illustrates the disk lower end  142  of the flexible stopper  140  being cracked open by the pressure force when the pump starts pumping. 
       System Operation 
       [0053]    As will be appreciated from  FIG. 5 , the inlet control valve  300  is in fluid communication with the inlet end  42  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 back flow that is directed towards the inlet control valve  300  is blocked from entering the regulator by the regulator check valve  100  as shown in  FIG. 10 . 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  as shown in  FIG. 13C . 
         [0054]    The inlet control valve  300  controls the inflow of outside air into the pump. If the tire pressure is low, the membrane  550  in the inlet control valve  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 , allowing outside filtered air to enter the central chamber  320  from passageway  393 . Outside air will then enter the first flexible duct  400 . The flow then exits the first flexible duct and enters in inlet check valve  100 , and then into the pump inlet  42 . As the tire rotates, the air flow in the pump is then compressed through the pump and then exits the pump outlet valve  200  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. 
         [0055]    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. 
         [0056]    The location of the pump assembly in the tire will be understood from  FIGS. 1 and 2 . In one embodiment, the pump air passageway  43  is positioned inside the tire sidewall, 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 inside the sidewall area 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. 
         [0057]    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. For example, the pump length may be any desired length, such as 10 degrees or more. As the length of the pump increases, the pump passageway will need to substantially open and close like a peristaltic pump. 
         [0058]    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. 
         [0059]    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.