Patent Abstract:
An elongate air tube is positioned within a tire sidewall cavity in contacting internal engagement with the tire sidewall to form an assembly. The air tube includes an internal elongate air passageway and wing projections projecting in opposite directions at an axially inward body portion. The wing projections seat within cavity pockets to retain the air tube within the cavity. The air tube body operatively compresses responsive to impinging stress forces from the tire sidewall against the air tube body, whereby the air tube body reconfiguring from an expanded unstressed configuration into a compressed configuration to constrict the air passageway. The air tube body decompresses into the expanded configuration upon reduction of the impinging stress forces against the air tube body.

Full Description:
FIELD OF THE INVENTION 
     The invention relates generally to air maintenance tires and, more specifically, to an air maintenance tire and pumping tube assembly therefore. 
     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 an air maintenance feature within a tire that will re-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 
     In one aspect of the invention, an elongate air tube is positioned within a tire sidewall cavity in contacting internal engagement with internal surfaces of the tire sidewall to form an assembly. The air tube includes a unitary air tube body and an internal preferably elliptical air passageway centrally positioned within the air tube body. The air tube body has wing projections projecting in opposite directions from an axially inward air tube body portion. The wing projections fold to accommodate insertion of the air tube body into the tire sidewall cavity and expand into cavity pockets once inserted to retain the air tube within the cavity. The air tube body operatively compresses responsive to impinging stress forces from the tire sidewall against the air tube body whereby the air tube body reconfiguring from an expanded unstressed configuration into a compressed configuration to constrict the air passageway. The air tube body decompresses into the expanded configuration upon reduction of the impinging stress forces against the air tube body. 
     In another aspect of the invention, a method of reconfiguring an air tube body within a tire sidewall includes: assembling the elongate air tube described above within a tire sidewall cavity in contacting internal engagement with contact surfaces of the tire sidewall, registering the wing projections into axially inward complementary pockets of the sidewall cavity to retain the tube within the sidewall cavity; flexing the tire sidewall to impinge stress forces from the sidewall contact surfaces on the air tube body; forcibly compressing the air tube body and collapsing the air passageway into a closed configuration. 
     DEFINITIONS 
     “Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100 percent for expression as a percentage. 
     “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
     “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
     “Chafer” is a narrow strip of material placed around the outside of a tire bead to protect the cord plies from wearing and cutting against the rim and distribute the flexing above the rim. 
     “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
     “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
     “Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure. 
     “Groove” means an elongated void area in a tire wall that may extend circumferentially or laterally about the tire wall. The “groove width” is equal to its average width over its length. A grooves is sized to accommodate an air tube as described. 
     “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 a shape adjacent grooves. 
     “Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  is an exploded isometric view of a tire, rim, and peristaltic tube assembly. 
         FIG. 2  is a side view of the tire with the peristaltic tube assembly within a tire sidewall. 
         FIG. 3A  is an isometric view of an outlet device component showing of the tube assembly. 
         FIG. 3B  is a plan view of the outlet device. 
         FIG. 3C  is a section view through the outlet device taken along the line  3 C- 3 C of  FIG. 3B . 
         FIG. 4A  is an isometric view of an inlet device component of the tube assembly. 
         FIG. 4B  is an isometric view of the inlet device with the filter sleeve in phantom. 
         FIG. 4C  is an isometric view of the inlet device component showing air intake schematically and the tube of the device in phantom. 
         FIG. 4D  is a sectional view through the inlet device taken along the line  4 D- 4 D of  FIG. 4B . 
         FIG. 4E  is a section view through the inlet device taken along the line  4 E- 4 E of  FIG. 4C . 
         FIG. 5A  is a side elevation view of the tire and peristaltic tube assembly shown schematically rotating against a road surface. 
         FIG. 5B  is a side elevation view of the tire and peristaltic tube assembly shown sequentially subsequent to the position of  FIG. 5A . 
         FIG. 6A  is a transverse section view through the tire and non-collapsed peristaltic tube assembly. 
         FIG. 6B  is an enlarged section view of the portion of the tire bead region, rim, and a non-collapsed peristaltic tube segment as identified in  FIG. 6A . 
         FIG. 7A  is a transverse section view through the tire and peristaltic tube assembly with the tube in a collapsed configuration. 
         FIG. 7B  is an enlarged section view of a portion of the tire bead region, rim, and collapsed tube segment identified in  FIG. 7A . 
         FIG. 8A  is an enlarged sectional exploded view of the tube and tube-receiving groove within the tire sidewall. 
         FIG. 8B  is a subsequent sequential sectional view to  FIG. 8A  showing insertion of the tube into the sidewall groove. 
         FIG. 9  is a graph of passageway length versus contact force normal for the tube. 
         FIG. 10A  is a is an enlarged sectional exploded view of a first alternative embodiment of a tube in an open condition and positioned within a tube-receiving groove within a tire sidewall. 
         FIG. 10B  is a an enlarged sectional view of the first alternative tube embodiment in a closed condition within the tire sidewall. 
         FIG. 11A  is an enlarged exploded sectional view of the first alternative tube embodiment and host sidewall groove. 
         FIG. 11B  is an exploded perspective view of a section of the first alternative tube embodiment and host sidewall groove. 
         FIG. 12A  is an enlarged sectional exploded view of a second alternative embodiment of a tube in an open condition and positioned within a tube-receiving groove within a tire sidewall. 
         FIG. 12B  is an enlarged sectional view of the second alternative tube embodiment in a closed condition within the tire sidewall. 
         FIG. 13A  is an enlarged exploded sectional view of the second alternative tube embodiment and host sidewall groove. 
         FIG. 13B  is an exploded perspective view of a section of the second alternative tube embodiment and host sidewall groove. 
         FIG. 14  is a graph of passageway length versus contact force normal for the second alternative tube embodiment. 
         FIG. 15A  is an enlarged sectional exploded view of a third alternative embodiment of a tube in an open condition and positioned within a tube-receiving groove within a tire sidewall. 
         FIG. 15B  is an enlarged sectional view of the third alternative tube embodiment in a closed condition within the tire sidewall. 
         FIG. 16A  is an enlarged exploded sectional view of the third alternative tube embodiment and host sidewall groove. 
         FIG. 16B  is an exploded perspective view of a section of the third alternative tube embodiment and host sidewall groove. 
         FIG. 17  is a graph of passageway length versus contact force normal for the third alternative tube embodiment. 
         FIG. 18A  is an enlarged sectional exploded view of a fourth alternative embodiment of a tube in an open condition and positioned within a tube-receiving groove within a tire sidewall. 
         FIG. 18B  is an enlarged sectional view of the fourth alternative tube embodiment in a closed condition within the tire sidewall. 
         FIG. 19A  is an enlarged exploded sectional view of the fourth alternative tube embodiment and host sidewall groove. 
         FIG. 19B  is an exploded perspective view of a section of the fourth alternative tube embodiment and host sidewall groove. 
         FIG. 20  is a sectional schematic view of a peristaltic tube within a tire sidewall and showing the distance X used to graph against the contact force normal (CFNOR) for the tube embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 ,  2 , and  6 A, a tire assembly  10  includes a tire  12 , a peristaltic pump assembly  14 , and a tire rim  16 . The tire mounts in conventional fashion to a pair of rim mounting surfaces  18 ,  20  adjacent outer rim flanges  22 ,  24 . The rim flanges  22 ,  24 , each have a radially outward facing flange end  26 . The tire is of conventional construction, having a pair of sidewalls  30 ,  32  extending from opposite bead areas  34 ,  36  to a crown or tire tread region  38 . The tire and rim enclose a tire cavity  40 . 
     As seen from  FIGS. 1 ,  2 ,  3 A through  3 C,  4 A through C,  5 A and  5 B, the peristaltic pump assembly  14  includes an annular air tube  48  that encloses an annular passageway  42 . While shown to configure an annular body, the air tube  48  may alternatively configured into other geometric shapes if desired. The tube  48  is formed of a resilient, flexible material such as plastic or rubber compounds that are capable of withstanding repeated deformation cycles wherein the tube is deformed into a flattened condition subject to external force and, upon removal of such force, returns to an original condition. The tube passageway  42  is generally circular in section and 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. In the configuration shown, the tube  48  is elongate and circular. An elongate groove of complementary shape to the tube  48  is formed to extend into an axially outward surface of a sidewall such as sidewall  30 , preferably in the geometric form of an annular ring. The other sidewall may be grooved or both sidewalls if so desired. The groove has an internal sectional profile complementary with the external geometry of the tube  48 . The groove complementary internal geometry accommodates close receipt of the tube  48 .  FIGS. 1 and 2  represent a prior art configuration of tube and groove, and are disclosed in detail in U.S. Pat. No. 8,042,586 B2, issued Oct. 25, 2011 entitled: “Self-Inflating Tire Assembly”, incorporated herein in its entirety by reference. 
     With reference to  FIGS. 1 ,  2 ,  3 A through  3 C and  4 A through E, the peristaltic pump assembly  14  further includes an inlet device  44  and an outlet device  46  spaced apart approximately 180 degrees at respective locations along the circumferential air tube  48 . The outlet device  46 , as shown in  FIGS. 3A through 3C , has a T-shaped configuration in which conduits  50 ,  52  direct air to and from the tire cavity  40 . An outlet device housing block  58  contains conduit arm ends  54 ,  56  that integrally extend at right angles from respective conduits  50 , 52 . The housing  58  is formed having an external geometry that complements and resides within the groove within the sidewall. 
     The inlet device  44  as seen in  FIGS. 1 ,  2  and  4 A through  4 E includes an elongate outward porous filtering sleeve  64  encasing an internal intake tube  60 . Ends  66 ,  68  of the tube  60  protrude from the sleeve  64  the tube  60  is configured having multiple air intake through-holes  62 . The outward sleeve  64  has an external geometry including a tubular inward air passage body  72  and an axially outward lobe body  70  operationally abutting against an outward surface of the tire sidewall and connecting to the body  72  by a neck junction  74 . Air intake indicated as shown enters through the porous filtering sleeve  64  and the apertures  62  into the intake tube  60 . Ends  66 ,  68  of the intake tube  60  are attached to the air tube  48  and reside therewith within the sidewall groove. So located, the tube  60  directs intake air into the tube  48  for pumping into the tire cavity. 
     As will be appreciated from  FIGS. 1 ,  2 ,  6 A,  6 B,  7 A and  7 B, the pump assembly  14  comprises the air tube  42  and an inlet and an outlet device  44 ,  46 . Devices  44 ,  46  are affixed in-line to the air tube  42  at respective locations 180 degrees apart. The pumping assembly  14  is thus inserted into the sidewall groove located at a lower sidewall region of the tire. With the tire  12  mounted to the rim  16 , the air tube  42  within the tire is located above the rim flange ends  26   
     With continued reference to Referring to  FIGS. 1 ,  2 ,  5 A and  5 B, the tire  12 , with the tube  42  positioned within a sidewall groove, rotates in a direction of rotation  76  against ground surface  78 . A compressive force  80  is directed into the tire at the tire footprint and acts to flatten a segment of the air tube passageway  42  opposite the footprint. Flattening of the segment of the passageway  42  forces air from the segment along tube passageway  42  in the direction shown by arrow  82  toward the outlet device  46 . 
     As the tire continues to rotate in direction  76  along the ground surface  78 , the tube  48  will be sequentially flattened or squeezed opposite the tire footprint segment by segment in a direction opposite to the direction of tire rotation. A sequential flattening of the tube passageway  42  segment by segment will result and cause evacuated air from the flattened segments to be pumped in the direction  82  within tube passageway  42  to the outlet device  46  and from the outlet device  46  to the tire cavity as shown. A valve system to regulate the flow of air to the cavity when the air pressure within the cavity falls to a prescribed level is shown and described in pending U.S. Patent Publication No. 2011/0272073, and incorporated herein by reference. 
     With the tire rotating in direction  76 , flattened tube segments are sequentially refilled by air flowing into the inlet device  44  as shown at  84  in  FIG. 5A . The inflow of air into the inlet device  44  flows into the tube passageway  42  and continues until the outlet device  46 , rotating counterclockwise as shown with the tire rotation, passes the tire footprint.  FIG. 5B  shows the orientation of the peristaltic pump assembly  14  in such a position. In the position shown, the tube  42  continues to be sequentially flattened segment by segment opposite the tire footprint by compressive force  80 . Air is pumped in the clockwise direction  82  to the inlet device  44  where it is evacuated or exhausted outside of the tire. When the tire rotates further in counterclockwise direction  76 , 1  the inlet device  44  eventually passes the tire footprint (as shown in  FIG. 5A ), and the airflow resumes to the outlet device  46 . Pumped air resumes its flow out and into the tire cavity  40 . Air pressure within the tire cavity is thus maintained at a desired level. 
     The above-described cycle is then repeated for each tire revolution, half of each rotation resulting in pumped air going to the tire cavity and half of the rotation the pumped air is directed back out the inlet device  44 . It will be appreciated that while the direction of rotation  76  of the tire  12  is as shown in  FIGS. 5A and 5B  to be counterclockwise, the subject tire assembly and its peristaltic pump assembly  14  will function in like manner in a (clockwise) reverse direction of rotation as well. The peristaltic pump is accordingly bi-directional and equally functional with the tire assembly moving in a forward or a reverse direction of rotation. 
     Referring to  FIGS. 6A ,  6 B;  7 A,  7 B;  8 A and  8 B, a “side-taper” tube configuration in a first embodiment is shown having a generally truncated wedge shaped cross-section. As used herein, “wedge” refers to the outboard portion of a tube that inserts into a tire sidewall groove. The wedge portion widens from an outer end at the tire sidewall groove entry toward an inner end of the tube positioned at the inward end of the groove. The portion referred to as “wedge portion” of a tube, in the described embodiments, accordingly is referencing the outboard side or portion of the tube that extends within a groove from a tire sidewall groove entry inward. As used herein, “cap portion” refers broadly to the portion of a tube at an inboard side or portion of the tube located at a the inward extremity of a host tire sidewall groove. As used herein, “wing protrusions” refer to laterally projecting portions of a tube body that extend outward from a main tube body and which, when the tube body is seated into its host tire sidewall groove, fit within ancillary groove chambers. The tube  84  is configured having an internal elliptical air passageway  86  in which a longitudinal axis of passageway  86  is oriented transversely through the tube. The air tube  84  has a forward wedge portion or region  88  of smaller diameter and an inboard larger diameter inboard end region  90 . The body of air tube  84  has a flat end surface  92  and divergent angled sides  94 ,  96  extending along the air tube from the small-diameter region  88  to the larger diameter inboard end  90 , terminating at rounded corners  100 ,  101  at an inboard end surface  98 . The wedge-shaped air tube  84  has preferred dimensions within the ranges specified below. The preferred dimensions are in millimeters: 
     D1: 6.46+/−0.1 mm; 
     D2: 0.7+/−0.01 mm; 
     D3: 1.46+/−0.05 mm; 
     L1: 4.25 mm; 
     L2: 2.2+/−0.1 mm; 
     L3: 1.78+/−0.01 mm; 
     α: 30.48 degrees 
     R1: 0.5 mm. 
     The groove chamber  110  within a sidewall  30  that receives the tube  84  has an internal configuration and geometry generally complimenting the geometry of tube  84 . The groove chamber  110  includes a narrow opening  102  at the outer surface of sidewall  30 ; a wedge shaped internal groove configuration extending from a smaller diameter entry region  104  and widening gradually along angled sides to a wider inboard groove chamber portion terminating at rounded groove inboard corner pockets or regions  106 ,  108 . The preferred dimensions of the groove components are as tabulated above and complement corresponding component dimensions of the tube. 
     Insertion of the tube  84  into the groove  110  is accomplished by compressing the tube into a flat enough dimension to fit within and through the opening  102 . Once situated within the groove chamber  110 , the tube  84  resiliently resumes its original form and fills the void of the groove chamber  110 . The radius corners  100 ,  101  of the tube are received within the respective radius pockets or corners  108 ,  106  of the groove. The corners  100 ,  101  so situated represent wing projections of the tube, located geometrically proximate the wider end of the tube, the wing projections residing within respective complementary configured regions of the groove chamber  110  at the axially inward, wider, groove chamber region. So located, the wing projections  100 ,  101  operationally resist lateral withdrawal of the air tube body from the groove chamber. The wider corners  100 ,  101  thus serve to retain the tube within the groove chamber without interfering or degrading the tube&#39;s capability of performing its primary intended function as an air pumping device through cyclical segment by segment collapsing and expansion of the tube in a rolling tire footprint. The tube  84  is retained within the groove chamber but can still react to the stresses imposed from flexure of the tire sidewall  30  to collapse segment by segment along the air passageway  86  to thereby pump air along the passageway and into the tire cavity. 
       FIG. 6A  is a transverse section view through a tire and  FIG. 6B  an enlarged view showing the tube  84  situated within a sidewall groove in a non-collapsed condition. The segment of the sidewall  32  shown is outside of the tire footprint and, therefore, is not impinging stress forces of the tube to collapse the tube passageway. 
       FIGS. 7A and 7B  shown the tire rotating against ground surface  78 , placing the sidewall  32  in a stressed condition. The sidewall  32  bulges outwardly and imparts stress forces on the segment of the tube  84  to collapse the tube  84  and the air passageway  86  as shown. Once the collapsed tube segment is no longer opposite the tire footprint against surface  78 , forces on the tube from the sidewall flexure are removed and the tube segment resumes its original, non-collapsed, configuration of  FIGS. 6A and 6B . configuration. 
     With reference to  10 A,  10 B;  11 A and  11 B, a second alternative embodiment of a peristaltic tube  112  in a “fish-hook” configuration is shown. In the tube  112 , a truncate wedge-shaped tube body  114  is defined by outwardly divergent sides  116 ,  118  and extends from a small diameter (D3) outboard flat surface  120  to an inboard domed cap region  122  of the tube  112 . Extending outward and arching downward from the cap region  122  are wing projections  124 ,  126  along the tube  112 . The surfaces  114 ,  116  of the wedge shaped body  114  outwardly diverge at an angle α. The wing projections  124 ,  126  project outward and arch backward toward the outboard flat surface  120  end of the body  116  at a reverse angle β. The wing projections  124 ,  126  each have an inward segment  132  which curves outwardly from the domed cap  122  at a radius R1 and an adjacent outward arching segment  128  that curves at a radius R2 to rounded ends  130 . The ends  130  are formed at a radius of curvature R3. An elliptical air passageway  134  is located within the tube  112 , having a major longitudinal axis oriented along a cross-sectional centerline of the tube. The passageway  134  has an outboard, axially outward end  136  situated within the wedge body  114  of the tube  112  and an inboard, axially inward end  138  situated within the cap region  122 , equidistant between the wing projections  124 ,  126 . The length of the elliptical passageway  134  is L2 and its transverse width is D2. D1 designates the wider span of the tube at the inboard, axially inward end and D3 the narrower end of the tube at surface  120 . L1 designates the length of the tube from end  136  to end  138  and L3 is the distance within the tube from the end surface  120  to a center of the elliptical passageway  134 . 
     The fish-hook shaped air tube  112  has preferred dimensions within the ranges specified below: 
     D1: 5.3+/−0.1 mm; 
     D2: 0.7+/−0.01 mm; 
     D3: 1.44+/−0.05 mm; 
     L1: 3.75 mm; 
     L2: 2.2+/−0.1 mm; 
     L3: 1.75+/−0.01 mm; 
     α: 24 degrees; 
     β: 30 degrees; 
     R1: 3.76 mm; 
     R2: 1.0 mm; 
     R3: 0.4 mm; 
     R4: 0.2 mm; 
     The groove  140  extends into sidewall  32  and is configured complementary to the tube  112  to include an entryway of width D3; a central chamber  144  including wedge shaped outboard chamber region  146  and inboard chamber cap region  148 . Two lateral chamber pockets  150 ,  152  are formed and dimensioned to accept the wing projections  124 ,  126  of the tube  112 . The dimension notation in  FIG. 11A  for the sidewall groove  144  corresponds with like-numbered dimensions in the tube  112 . 
     Insertion of the tube  112  into the groove  140  is accomplished by compressing the tube into a flat enough dimension to fit within and through the opening  142 . The wing projections  124 ,  126  resiliently fold inward to accommodate insertion. Once situated within the groove chamber  144 , the tube  112  resiliently resumes its original form and fills the void of the groove chamber  144 . The radius corners  130  of the wing projections  124 ,  126  of the tube are received within the respective radius pockets or corners  150 ,  152  of the groove. As shown, the wing projections  124 ,  126  are situated geometrically proximate the wider cap  122  of the tube  112 . So located, the wing projections  124 ,  126 , as with the first embodiment of  FIGS. 8A and 8B , operationally resist lateral withdrawal of the air tube body  112  from the groove chamber  140 . The arching wing projections  124 ,  126  thus serve to fold inward during tube insertion and, once inserted, snap-in groove pockets to retain the tube  112  within the groove chamber  140 . The wing projections in the forms shown in the alternative embodiments do not interfere with or degrade the tube&#39;s capability of performing its primary intended function as an air pumping device through cyclical segment by segment collapsing and expansion of the tube in a rolling tire footprint. The tube  112  is retained within the groove chamber by wing projections  124 ,  126  but can still react to the stresses imposed from flexure of the tire sidewall  32  to collapse segment by segment along the air passageway  134  to thereby pump air along the passageway and into the tire cavity. 
       FIG. 10A  is a transverse section view through a tire showing the tube  112  within the groove  140  in a non-collapsed condition outside of a rolling tire footprint.  FIG. 10B  shows the tube  112  in a collapsed condition within the groove  140  as the segment of tire sidewall  32  within a rolling tire rotates to a location opposite a tire footprint. Once the collapsed tube segment is no longer opposite the tire footprint, forces imposed on the tube from the sidewall flexure are removed and the tube segment resumes its original, non-collapsed, configuration shown in  FIG. 10A . 
     Referring to  FIGS. 12A ,  12 B,  13 A and  13 B, a third embodiment of a peristaltic tube  154  is shown in a winged “bull-horn” configuration. In the tube  154 , a truncate wedge-shaped tube body  156  is defined by outwardly divergent sides that extend from a small diameter (D3) outboard flat end surface  160  to an inboard domed cap region  158  of the tube  154 . Extending outward from generally a midsection of the tube  154  are oppositely directed triangular wing projections  162 ,  164  each extending to an end  165  having a radius R3. The wing projections  162 ,  164  are distanced L3 from the end wall  160  and the tube is dimensioned in transverse section L1. The sides of the wedge shaped body  156  outwardly diverge at an angle α to a curved body section  163  having a radius R2. The wing projections  162 ,  164  project outward at right angles from the body  154 . The cap region  158  of the body  154  has a radius of R2. An elliptical air passageway  166  is located within the tube  154 , having a major longitudinal axis oriented along a cross-sectional centerline of the tube. The passageway  166  has an outboard, axially outward end  168  situated within the wedge body  156  of the tube  154  and an inboard, axially inward end  170  situated within the cap region  158 . The length of the elliptical passageway  166  is L2 and its transverse width is D2. D1 designates the tip to tip span of the tube and D3 the narrower end of the tube at surface  160 . L3 is the distance within the tube from the end surface  160  to a center of the elliptical passageway  166 . 
     The air tube  154  accordingly has preferred dimensions within the ranges specified below: 
     D1: 6.03+/−0.1 mm; 
     D2: 0.7+/−0.01 mm; 
     D3: 1.05+/−0.05 mm; 
     L1: 3.74 mm; 
     L2: 2.2+/−0.1 mm; 
     L3: 1.78+/−0.01 mm; 
     α: 37 degrees; 
     R1: 1.35 mm; 
     R2: 0.7 mm; 
     R3: 0.13 mm; 
     The groove  172  is complementarily configured to accept tube  154  and extends into one of the tire sidewalls such as  32 . The groove is configured to complement to the tube  154  and includes an entryway  174  of width D3; a central chamber including wedge shaped outboard chamber region  176  and inboard chamber cap region  178 . Two lateral chamber pockets  180 ,  182  are formed and dimensioned to accept the wing projections  162 ,  164  of the tube  154 . The dimension notations in  FIG. 13A  for the sidewall groove  172  correspond with like-numbered dimensions to the tube  154  as indicated. 
     Insertion of the tube  154  into the groove  172 , as with previous tube embodiments, is accomplished by compressing the tube into a flat enough dimension to fit within and through the opening  174 . The wing projections  162 ,  164  resiliently fold inward to accommodate insertion. Once situated within the groove chamber, the tube  154  resiliently resumes its original form and fills the void of the groove chamber. The radius tips  163  of the wing projections  162 ,  164  of the tube “snap-fit”, i.e. resiliently flex outward, into respective radius pockets  180 ,  182  of the groove  172 . So located, the wing projections  162 ,  164 , as with previously described embodiments, operationally resist lateral withdrawal of the air tube body  154  from the groove chamber. The wing projections  162 ,  164  thus serve to retain the tube within the groove  172  without interfering with or degrading the tube&#39;s capability of performing its primary intended function as an air pumping device that cyclical deforms segment by segment by collapsing and expansion of the tube in a rolling tire footprint. The tube  154  is retained within the groove chamber by wing projections  162 ,  164  but can still react to the stresses imposed from flexure of the tire sidewall  32 , thus collapsing segment by segment along the air passageway  166  to thereby pump air along the passageway and into the tire cavity. 
       FIG. 12A  is a transverse section view through a tire showing the tube  154  oriented within the groove  172  in a non-collapsed condition outside of a rolling tire footprint.  FIG. 12B  shows a segment of the tube  154  in a collapsed condition within the groove  172  as the segment reaches a location opposite a tire footprint. Once the collapsed tube segment is no longer opposite the tire footprint, forces imposed on the tube from the sidewall flexure are removed and the tube segment resumes its original, non-collapsed, configuration shown in  FIG. 12A . 
     Referring to  FIGS. 15A ,  15 B,  16 A and  16 B, a fourth embodiment of a peristaltic tube  184  is shown in a “mushroom” configuration. The tube  184  includes a truncate wedge-shaped outboard tube body portion  186  defined by outwardly divergent sides extending from a small diameter (D3) flat end surface  190  to an inboard domed cap region  188 . Extending outward from the cap portion  188  are oppositely directed wing projections  192 ,  194  each having an upper arcuate surface  193  of radius R1 and an underside flat surface  195 . The wing projections  192 ,  194  are distanced L4 from the end wall  190  and the tube is dimensioned in transverse section L1. The sides of the wedge shaped body  186  outwardly diverge at an angle α and intersect the wing projection underside surface  195 . The cap region  188  of the tube  184  is flat on the inward end. An elliptical air passageway  196  is located within the tube  184 , having a major longitudinal axis oriented along a cross-sectional centerline of the tube. The passageway  196  has an outboard, axially outward end  198  situated within the wedge body portion  186  and an inboard, axially inward end  200  situated within the cap region  188 . The length of the elliptical passageway  196  is L2 and its transverse width is D2. D1 designates the tip to tip span of the tube and D3 the diameter of the narrower end of the tube at surface  190 . L3 is the distance within the tube from the end surface  190  to a center of the elliptical passageway  196 . 
     The air tube  184  accordingly has preferred dimensions within the ranges specified below: 
     D1: 6.39+/−0.1 mm; 
     D2: 0.7+/−0.01 mm; 
     D3: 1.44+/−0.05 mm; 
     L1: 4.25 mm; 
     L2: 2.2+/−0.1 mm; 
     L3: 1.78+/−0.01 mm; 
     L4: 1.83+/−0.05 mm; 
     α: 24 degrees; 
     R1: 1.85 mm; 
     The groove  202  is configured to accept tube  184  and extends into a tire sidewall such as sidewall  32 . The groove  202  is configured complementary to the tube  184  and includes an entryway  204  of width D3; a central chamber including a wedge shaped outboard chamber region  206  and an inboard chamber cap region  208 . Two lateral chamber pockets  210 ,  212  are formed and dimensioned to accept the wing projections  192 ,  194  of the tube  184 . The dimension notations in  FIG. 16A  for the sidewall groove  202  correspond with like-numbered dimensions to the tube  184  as indicated. 
     Insertion of the tube  184  into the groove  202 , as with previous tube embodiments, is accomplished by compressing the tube into a flat enough dimension to fit within and through the opening  204 . The wing projections  192 ,  194  resiliently fold inward to accommodate insertion. Once situated within the groove chamber, the tube  184  resiliently resumes its original form and fills the void of the groove chamber. The wing projections  192 ,  194  of the tube are received within the respective ancillary pockets  210 ,  212  of the groove  202 . So located, the wing projections  192 ,  194 , as with previously described embodiments, operationally resist lateral withdrawal of the air tube body  184  from the groove chamber. The wing projections  192 ,  194  thus serve to retain the tube  184  within the groove  202  without interfering or degrading the tube&#39;s capability of performing its primary intended function as an air pumping device that cyclical deforms segment by segment in a rolling tire footprint. The tube  184  is retained within the groove chamber by wing projections  192 ,  194  yet can still react to the stresses imposed from flexure of the tire sidewall  32  to collapse segment by segment along the air passageway  196  to thereby pump air along the passageway and into the tire cavity. 
       FIG. 15A  is a transverse section view through a tire showing the tube  184  oriented within the groove  192  in a non-collapsed condition outside of a rolling tire footprint.  FIG. 15B  shows a segment of the tube  184  in a collapsed condition within the groove  192  as the segment reaches a location opposite a tire footprint. Once the collapsed tube segment is no longer opposite the tire footprint, forces imposed on the tube from the sidewall flexure are removed and the tube segment resumes its original, non-collapsed, configuration shown in  FIG. 15A . 
     Referring to  FIGS. 18A ,  18 B,  19 A and  19 B, a fifth embodiment of a peristaltic tube  214  is shown in a “fishtail” configuration. The tube  214  includes a truncate wedge-shaped outboard tube body portion  216  defined by outwardly divergent sides extending from a small diameter (D3) flat end surface  220  to an inboard domed cap region  218 . Extending outward from the cap portion  218  are oppositely directed wing projections  222 ,  224  each having an upper generally planar surface  223  and an underside planar surface  225 . The wing projections  222 ,  224  have a thickness L4 and are at a distance L1 from the end wall  220 . The sides of the wedge shaped body portion  216  outwardly diverge at an angle α and intersect the wing projection underside surface  225 . The cap region  218  of the tube  214  is flat across the inward end. An elliptical air passageway  226  is located within the tube  214 , having a major longitudinal axis oriented along a cross-sectional centerline of the tube. The passageway  226  has an outboard, axially outward end  228  situated within the wedge body portion  226  and an inboard, axially inward end  230  situated within the cap region  218 . The length of the elliptical passageway  226  is L2 and its transverse width is D2. D1 designates the tip to tip span of the tube and D3 the diameter of the narrower end of the tube at surface  220 . L3 is the distance within the tube from the end surface  220  to a center of the elliptical passageway  226 . 
     The air tube  184  accordingly has preferred dimensions within the ranges specified below: 
     D1: 6.4+/−0.05 mm; 
     D2: 0.75+/−0.01 mm; 
     D3: 1.45+/−0.05 mm; 
     D4: 2.6+/−0.01 mm; 
     L1: 5 mm; 
     L2: 3+/−0.01 mm; 
     L3: 2.18+/−0.01 mm; 
     L4: 1+/−0.05 mm; 
     α: 28 degrees. 
     A groove  232  is configured to accept tube  214  and extends into a tire sidewall such as sidewall  32 . The groove  232  is configured complementarily to the tube  214  and includes an entryway  234  of width D3; a central chamber including a wedge shaped outboard chamber region  236  and an inboard chamber cap region  238 . Two lateral chamber pockets  240 ,  242  are formed and dimensioned to accept the wing projections  222 ,  224  of the tube  214 . The dimension notations in  FIG. 19A  for the sidewall groove  232  correspond with like-numbered dimensions to the tube  214  as indicated. 
     Insertion of the tube  214  into the groove  232 , as with previous tube embodiments, is accomplished by compressing the tube into a flat enough dimension to fit within and through the opening  234 . The wing projections  222 ,  224  resiliently fold inward to accommodate insertion. Once situated within the groove chamber, the tube  214  resiliently resumes its original form and fills the void of the groove chamber. The wing projections  222 ,  224  of the tube snap-fit within the respective ancillary pockets  240 ,  242  of the groove  232  by resiliently flexing outward into a non-folded configuration. So located, the wing projections  222 ,  224 , as with previously described embodiments, operationally resist lateral withdrawal of the air tube body  214  from the groove chamber. The wing projections  222 ,  224  thus serve to retain the tube  214  within the groove  232  without interfering or degrading the tube&#39;s capability of performing its primary intended function as an air pumping device that cyclical deforms segment by segment in a rolling tire footprint. The tube  214  is retained within the groove chamber by wing projections  222 ,  224  yet can still react to the stresses imposed from flexure of the tire sidewall  32  to collapse segment by segment along the air passageway  226  to thereby pump air along the passageway and into the tire cavity. 
       FIG. 18A  is a transverse section view through a tire showing the tube  214  oriented within the groove  232  in a non-collapsed condition outside of a rolling tire footprint.  FIG. 18B  shows a segment of the tube  214  in a collapsed condition within the groove  232  as the segment reaches a location opposite a rolling tire&#39;s footprint. Once the collapsed tube segment is no longer opposite the tire footprint, forces imposed on the tube from the sidewall flexure are removed and the tube segment resumes its original, non-collapsed, configuration shown in  FIG. 18A . 
     The alternative embodiments of the peristaltic tube are utilized to pump air along an internal passageway to a tire cavity. The wing projections of each embodiment deform and fold to accommodate insertion of a tube into a groove, and then snap-in groove pockets to functionally retain the tube within its host sidewall groove without compromising the pumping efficiency of the tube body. Each embodiment is configured having a wedge tube side facing an outward sidewall entryway of the host groove, the wedge side increasing in diameter from the groove entryway inward. At the opposite side each tube configuration, a cap region is defined that extends to an inner end of the host groove. Two oppositely directed wing projections extend longitudinally along the tube body and project outward into cavity side chambers of the host groove. The wing projections are configured differently in each of the alternative embodiments but share the structural trait of oppositely directed wing projections which fold to accommodate tube insertion into a host groove, and snap-in groove side chambers once the tube is seated, thus accomplishing the wing projection purpose of tube retention without degrading tube pumping performance. 
     The performance of each of the tube configurations in providing adequate air pumping along its internal air passageway for given tube passageway sizes may be measured and compared. Such a comparison reveals which tube and wing projection embodiment produces the requisite pressure for pumping air along the passageway for the widest range of passageway sizes while also providing the snap-in retention capability afforded by wing projection configurations.  FIG. 20  shows the fishhook tube  112  embodiment within a tire groove of sidewall  32 . “X” represents the arc distance from the “start” end of the elliptical passageway  134  to the opposite end, designated “end”. The contact pressure between the two opposed halves  244 ,  246  of the passageway required to collapse the elliptical passageway is CFNOR (Contact Force Normal, or Contact Pressure). In  FIGS. 9 ,  14 , and  17 , empirical test results are presented, graphing Y-axis CFNOR vs. X-axis sizes of passageway arcs “X” for the “wedge” tube embodiment shown in  FIGS. 8A ,  8 B; the “winged” tube configuration shown in  FIGS. 13A ,  13 B; and the “lobe” tube embodiment shown in  FIGS. 16A ,  16 B, respectively. The required force required for pumping is as indicated by horizontal line as 0.30 CFNOR. It will be noted from the graphs that the sizing of the elliptical passageway selected for the peristaltic tube affects the pressure required to close the tube passageway. Moreover, the pressure required to close the air passageway is affected by the tube configuration employed. Each of the tube configurations described herein were tested to measure the CFNOR force required to collapse the tube passageway for a range of X-sized passageways. 
     As a result of the comparison, for pure snap-in operation of the alternative tube configurations, the tubes, in order of performance are the “mushroom” tube; the “fish-hook” tube; the “bull-horn” tube; the “fish-tail” tube; and the “side-taper” tube. For peristaltic pumping intent, measuring the pinching force as a metric, the “fish-hook” tube ranked first. In combining both retention capability and pumping efficiency, the “mushroom” and “fish-hook” tube configurations provided the best optimized performance followed by the “fishtail”, “taper” and “bull-horn” configurations. 
     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.

Technology Classification (CPC): 8