Abstract:
A tire assembly and method includes one or more elongate air passageway formed within a tire component, such as a tire sidewall. The air passageway is configured as a series or string of elongate cavities, adjacent cavities connected end to end by an elongate connecting channel. The connecting channel is dimensioned having a channel diametric size smaller than a cavity diametric size. Positioned within the tire component, the air passageway sequentially collapses segment by segment as each of the cavities pass sequentially over a rolling tire footprint. Air is pumped by the sequential air passageway collapse with the smaller dimensioned connecting channel(s) acting as valve components to directionally keep the pumped air moving between an air passageway air inlet and an air passageway air outlet and from there into the tire cavity.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to air maintenance tires and, more specifically, to an air pumping passageway within a tire for maintaining air pressure within a tire cavity. 
       BACKGROUND OF THE INVENTION 
       [0002]    Normal air diffusion reduces tire pressure over time. The natural state of tires is under inflated. Accordingly, drivers must repeatedly act to maintain tire pressures or they will see reduced fuel economy, tire life and reduced vehicle braking and handling performance. Tire pressure monitoring systems have been proposed to warn drivers when tire pressure is significantly low. Such systems, however, remain 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 
       [0003]    In one aspect of the invention, a tire assembly and method includes one or more elongate air passageway formed within a tire component, such as a tire sidewall. The air passageway is configured as a series or string of elongate cavities, adjacent cavities connected end to end by an elongate connecting channel. The connecting channel is dimensioned having a channel diametric size smaller than a cavity diametric size. Positioned within the tire component, the air passageway sequentially collapses segment by segment as each of the cavities pass sequentially over a rolling tire footprint. Air is pumped by the sequential air passageway collapse in the rolling tire from cavity to cavity through the connecting channels between the cavities. The smaller dimensioned connecting channel(s) acts as a valve component to prevent back flow of air within the air passageway and to direct the air between an air passageway air inlet and an air passageway air outlet. 
         [0004]    In another aspect, the adjacent cavities in the string of cavities have a respective elongate length L sized to operatively allow compression of only one cavity at a time above a rolling tire footprint. Each cavity of the air passageway and connecting channel(s) resiliently returns to an un-flattened condition when repositioned by tire rotation outside the rolling tire footprint. 
       Definitions 
       [0005]    “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. 
         [0006]    “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
         [0007]    “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
         [0008]    “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. 
         [0009]    “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
         [0010]    “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
         [0011]    “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. 
         [0012]    “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. 
         [0013]    “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. 
         [0014]    “Lateral” means an axial direction. 
         [0015]    “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. 
         [0016]    “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. 
         [0017]    “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. 
         [0018]    “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. 
         [0019]    “Peristaltic” means operating by means of wave-like contractions that propel contained matter, such as air, along tubular pathways. 
         [0020]    “Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire. 
         [0021]    “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. 
         [0022]    “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. 
         [0023]    “Tread element” or “traction element” means a rib or a block element defined by having a shape adjacent grooves. 
         [0024]    “Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The invention will be described by way of example and with reference to the accompanying drawings in which: 
           [0026]      FIG. 1  is a perspective front view of tire showing inlet, outlet and vein cavity location for a 180 degree system. 
           [0027]      FIG. 2  is a side view of tire showing inlet, outlet and vein cavity location of 180 degree system. 
           [0028]      FIG. 2A  is a side view of tire showing inlet, outlet and vein cavity location of 360 degree system. 
           [0029]      FIG. 3A  is a section view taken from  FIG. 2  showing the inlet. 
           [0030]      FIG. 3B  is an enlarged view of the inlet taken from  FIG. 3A . 
           [0031]      FIG. 4A  is a section view taken from  FIG. 2  showing the outlet. 
           [0032]      FIG. 4B  is an enlarged view of outlet taken from  FIG. 4A . 
           [0033]      FIG. 5A  is a perspective view of inlet. 
           [0034]      FIG. 5B  is an exploded perspective view of inlet. 
           [0035]      FIG. 6A  is a perspective view of outlet. 
           [0036]      FIG. 6B  is an exploded perspective view of inlet. 
           [0037]      FIGS. 7 through 10  are alternative embodiments of four types of cavity shapes. 
           [0038]      FIG. 11  is a section view of core in place to create vein cavity. 
           [0039]      FIG. 12  is a section view of core removed leaving vein cavity. 
           [0040]      FIG. 13  is a side view of tire with vein cavities showing tire rotation and air flow direction through vein cavities. 
           [0041]      FIGS. 14A  through E are diagrammatic views depicting air flow moving from cavity to cavity as the tire rotates. 
           [0042]      FIG. 15  is a perspective front view of tire showing inlet, outlet and vein tube location for a 360 degree system. 
           [0043]      FIG. 16  is an enlarged section view of vein tube taken from  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    Referring to  FIGS. 1 ,  2 A,  2 B,  3 A and  3 B, a tire assembly  10  includes a tire  12  of conventional construction having a pair of sidewalls  14 ,  16  extending from respective beads  20 ,  22  to a tire tread  18 . As part of the assembly, one or more elongate air passageway(s)  24  are incorporated into respective tire component(s). The passageway  24  of the subject disclosure is shown as integrated into tire sidewall  14  but it will be appreciated that multiple passageways may be deployed in one or both sidewalls if desired. The air passageway  24  extends internally within the sidewall  14  between an air inlet portal  26  opening to receive air into the passageway and an air outlet portal  28  operative to direct air from the passageway toward a tire cavity  86 . 
         [0045]    The passageway  24  constitutes an air pumping vein mechanism operating to pump air from outside of the tire into the tire cavity as the tire rotates, whereby maintaining the tire air pressure at an optimal level. An inlet valve  30  is mounted at the inlet portal  26  and an outlet valve  58  at the outlet portal  28 . The inlet valve  30 , as shown in  FIGS. 3A ,  3 B,  5 A and  5 B is configured as a ball-type valve having an elbow connector housing  32  extending from a passageway-coupling end  34  to an inlet end  36 . The connector housing  32  has a through-bore which receives a cylindrical sleeve member  38  having an internally threaded through-bore  40 . A biasing spring  42  seats within the bore  40  and a ball member  44  seats within the bore  40  against the biasing spring  42 . A retainer ferrule  46  having a through bore is externally threaded at  48  and threads into the sleeve member  38  to hold the inserted components  42 ,  44  in place. The sleeve  38  inserts into the inlet end  36  of the connector body and an assembly cap  50  is internally threaded at  52  to engage over the connector end  36 . A porous filter member  56  seats within the cap  50 . The cap is provided with a notch  54  along an outer circumferential surface for the purpose of orientation of the assembly. 
         [0046]    The completely assembled inlet valve  30  when attached to the connector housing will allow the entry of ambient air through the filter member  56  and into the valve sleeve  38 . The spring  42  biases the valve ball member  44  into a closed position until a pressure at a down stream side of the valve falls below a preset level. When the pressure is below the preset level, the valve opens and allows air to pass into the valve and then into the inlet portal  26  of the passageway. When the pressure at the downstream side of the inlet valve  30  is at or above the threshold pressure, the ball member  44  is biased by spring  42  into a closed position, whereby closing air flow through the inlet valve  30 . 
         [0047]    The outlet valve  58  operates in a comparable manner to the inlet valve  30 . As seen in  FIGS. 4A ,  4 B,  6 A and  6 B, the outlet valve  58  includes an elbow connector housing  60  having a through-bore extending between a passageway coupling end  62  and an outlet end  64 . The connector housing  60  receives a cylindrical sleeve member  66  having an internally threaded through-bore  68 . A biasing spring  70  seats within the bore  68  and a ball member  72  seats within the bore  68  against the biasing spring  70 . A retainer ferrule  74  having a through bore is externally threaded and threads into the sleeve member  66  to hold the inserted components  70 ,  72  in place. The sleeve  66  inserts into the outlet end  64  of the connector housing  60  and an assembly cap  76 , internally threaded along a through-bore  78 , engages over the connector housing end  64 . A porous filter member  82  seats within the cap member  76 . The notch  80  in each cap  76  is for orientation of the assembly. 
         [0048]    The complete assembled outlet valve  58  attaches to the air passageway  24  at the outlet portal  28 . Air pumped along the passageway  24  exits the passageway through valve  58 . The spring  70  within valve  58  biases the valve ball member  72  into a closed position until a pressure within the tire cavity  84  falls below a preset desired level. When the pressure is below the preset level, the valve  58  opens and allows air to pass from the passageway  24  into the tire cavity  84 , whereby maintaining the tire air pressure at a desired level. When the cavity air pressure is at or above the desired level, the ball member  72  is biased by spring  70  into a closed position, whereby closing air flow from passageway  24  into the tire cavity  84 . 
         [0049]    Referring to  FIGS. 7 through 10 , the air passageway  24  is configured integrally within a tire component such as a sidewall or tread component. The passageway  24  is constructed as a series or string of relatively wide elongate cavities  86  alternating with and interconnected by narrower and shorter, elongate connector channels. For the purpose of illustration, only a portion of the passageway  24  is represented by the singular cavity  86  in alternative embodiments of  FIGS. 7 through 10 , with a pair of the narrow, connector channels  88 ,  90  adjoining the cavity on opposite sides. It will be appreciated that the actual passageway  24  will comprises a repeating alternating series of multiple cavities and connecting channels. Thus constructed, the passageway  24  forms a vein operable to pump inlet air from the inlet portal  26  along the passageway  24  to the outlet portal  28  as the tire rotates. The outlet air is directed from the outlet portal  28  to the tire cavity as explained previously. The principle, as explained in more detail below, is to push air from cavity into a second cavity and then a third cavity until the air is forced from the passageway  24  into the tire cavity, whereby re-inflating the cavity to a desired pressure. 
         [0050]    The cavities  86  in each embodiment of  FIGS. 7 through 10  are generally of larger diametric dimension than the interconnecting connector channels ( 88 ,  90 ). A maximum length L of each cavity is a footprint length of the tire. The length L is at least or a minimum of 10 mm. The connecting channel between two cavities 86 has a maximum diametric width within a range of 5 to 50 percent of a maximum diametric dimension of each of the cavities and the connecting channel is at least 5 mm in length. 
         [0051]    The alternative embodiments of  FIGS. 7 through 100  show cavity configuration options. In  FIG. 7 , a symmetrical cavity of constant diameter is shown.  FIG. 8  shows an alternative in which the cavities have a wider width dimension than  FIG. 7 , whereby more pressure generation by each cavity through compression is possible.  FIG. 9  shows a cavity increasing in width from both ends to a cavity center. In  FIG. 9 , the cavity  86  increases gradually in width or diameter from one end to the opposite end. This configuration is accordingly a directional pumping alternative, capable of pumping air only in the direction in which the cavity is increasing diametrically.  FIGS. 7 ,  8  and  10 , in contrast, are bi-directional cavity configurations, capable of pumping air in either direction. 
         [0052]    The invention is intended to create a series or string of cavities  86  to push air from one cavity into a second cavity into a third cavity, etc., until the forced air exits the outlet portal  28  and is directed into the tire cavity  84 . The passageway  24  may be formed into a sidewall or tread component during tire manufacture as will be seen from  FIGS. 11 and 12 . An insert  92  is placed within the tire component during tire build and cure, the insert  92  having cavity-forming regions  94  and connector channel-forming regions  96 . Once the tire is formed and cured, the insert  92  is removed leaving a passageway  24  of intended cavity  86 /channel  88  configuration as shown in  FIG. 12 . The passageway  24  may be formed by any known technique such as by sidewall insert or an internal core removed after tire cure. 
         [0053]    The principle of the air pumping system within a rolling tire is shown by  FIG. 13 . As the tire rotates in the indicated direction, the passageway  24  is sequentially flattened segment by segment, forcing air in the direction of arrow  102 . Engagement of the tire against ground surface  98  causes the segment of passageway  24  opposite of the tire footprint  100  to be squeezed and constricted. This forces air along the passageway  24 . Air is accepted into the vein or passageway  24  by means of inlet valve  30  communicating with the air outside the tire. The outlet valve  58  at an opposite end of the passageway  24  communicates air evacuated from the passageway  24  into the tire cavity  84 . The passageway  24  in  FIG. 13  extends substantially along a 180 degree path around the sidewall  14  between the inlet portal  26  and the outlet portal  28 .  FIG. 15  shows a 360 degree air passageway  24  formed within and substantially circumscribing the sidewall  14 . As with the 180 degree version of  FIG. 13 , the 360 degree air passageway extends between the inlet and outlet portals  26 ,  28  which are fitted with valving such as inlet valve  30  and outlet valve  58  (not shown) described previously. 
         [0054]    All of the cavities  86  have a larger diametric width (e.g. 1.5 mm) than the connector channels  88  (e.g. 0.3 mm) with adjacent cavities separated and connected by a small diametered connector channel. As will be seen from  FIGS. 13 and 14A  through  14 E, the vein concept under which air passageway  24  operates through the sequentially squeezing of cavities  86  one by one as the cavities roll through positions opposite the rolling tire footprint. When the tire rolls, air taken into the passageway  24  through inlet portal  26  is accepted into cavity C 1 . As cavity C 1  enters a position opposite the footprint  100  ( FIG. 14B ), cavity C 1  is squeezed, pushing air into cavity C 2  by means of connector channel  90 . The cavity C 1  need not be completely collapsed to push air through the connector channel  90  and into cavity C 2 . As the connector channel  90  between the cavities C 1 , C 2  enters into position opposite the rolling tire footprint  100 , because of the small diameter of connector channel  90 , it will completely be squeezed closed with the tire deflection. 
         [0055]    As the tire continues to incrementally roll further ( FIG. 14C ), the cavity C 1  is in its collapsed state, air has been forced into cavity C 2 , and connector channel  90  between C 1  and C 2  is fully closed. As cavity C 2  enters into position opposite the footprint  100 , the cavity C 2  is progressively collapsed, forcing the air therein in direction  102  and into the cavity C 3  by means of connector channel  90  between C 2  and C 3 . As cavity C 1  leaves its position opposite the rolling tire footprint ( FIG. 14D ), cavity C 1  is released and reopens to air intake through inlet portal  26 . Air is thus progressively and sequentially pushed from cavity to cavity ( FIG. 14E ) until it reaches the outlet portal  28 . The valve  58  will open if the air pressure within the tire cavity  84  is below a desired threshold level set by the spring bias within the valve, thus directing air from the air passageway  24  into the tire cavity. 
         [0056]    While a five cavity system, C 1  through C 5  is shown for illustration purposes in  FIGS. 14A through 14D , more or fewer cavities may be deployed into an air passageway if desired without departing from the invention. The length of each cavity, L1 approximately equal to 50 mm in the example shown, is selected to be less than a compressed zone at the rim level. Stated differently, the length L1 will be selected to be less than the footprint length of the tire as it rotates so as to effect the progressive sequential collapse of cavities (e.g. C 1  through C 5 ) one by one. 
         [0057]    The “vein” operating principle of the subject invention has advantages over a system employing an air passageway pumping mechanism of constant diametric dimension. In a constant diameter system, a complete collapse of a segment opposite a rolling tire footprint is required to push air along the passageway and avoid any back-leakage of air. Obtaining a complete collapse of the air passageway requires a precise location of the air passageway to obtain the requite force necessary for a complete collapse. In the subject system, in contrast, different cavities (C 1  through C 5  e.g.) are created in series, adjacent cavities linked by a small diameter connector channel that functions as a valve. A small deformation of the tire is sufficient to cause a small deformation in the cavity opposite a rolling tire footprint. This small deformation in cavity C 1  will cause air to flow through a small connector channel into the adjacent cavity C 2  with a little further tire rotation. Because the connector channel is sized diametrically small, the force on the channel will be sufficient to close the connector channel (valve) and prevent air backflow. Because of the inherent valving provided by the small diameter connector channels, location of the air passageway is less critical and the air pumping system of the invention is less sensitive to tire loading. 
         [0058]    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. For example, the invention is not limited to the passageway cavity and connector channel configurations shown or the preferred dimensional specifications of the passageway cavities and channels. 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.