Patent Application
20170157999
The present invention relates generally to air maintenance tires and, more specifically, to a tire assembly incorporating an air pumping mechanism into a tire for maintaining tire air pressure.
Properly inflated tires are important for vehicle operational efficiency. Many vehicles, particularly trucks, have dual tires mounted in tandem on an axle. Since, normal air diffusion reduces tire pressure over time, the natural state of such tires is underinflated. In a dual tire system, one or both tires may lose air resulting in the need for re-pressurization. It is desirable, therefore, to incorporate an air maintenance feature within a tire that will self-maintain the tire air pressure in order to compensate for any reduction in tire pressure over time without a need for driver intervention. For dual tire systems, such an air maintenance feature should be capable of easy, economical and efficient installation into a tire and be capable of maintaining both tires in the tandem at requisite equal pressure.
An air maintenance tire system and method in accordance with the present invention includes an air pumping mechanism configured to maintain air pressure within both a first and a second tire mounted side-by-side. The system includes a first tire and a second tire mounted in side-by-side relationship to an axle, and a control valve assembly including a control valve housing attached to an elongate valve stem projecting from a rim of the first tire. The control valve assembly enables a flow of pressurized air into the tire cavities of the first tire and the second tire from a pumping air passageway within a first sidewall of the first tire. A connecting tube extends between the sidewall air passageway and the control valve assembly, the connecting tube having a one way valve mounted to control pressurized air flow into the control valve housing from the sidewall air passageway.
In another aspect, the air maintenance tire system includes with the control valve assembly a relief valve mounted to the control valve housing to vent air pressure from the control valve housing in the event that the air pressure exceeds a preset threshold.
“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'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 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.
“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 (CP).
“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'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.
The present invention will be described by way of example and with reference to the accompanying drawings, in which:
Referring to
The peristaltic principles of incorporating a deformable air tube within a tire are shown and described in U.S. Pat. No. 8,113,254 entitled SELF-INFLATING TIRE incorporated herein by reference in its entirety. The tube 34 may be incorporated within an annular tire passageway formed within the tire proximate a tire bead region. As the tire 12 rotates, air from outside the tire may be admitted into the tube 34 and pumped along the air tube by the progressive squeezing of the tube within the tire as the tire rotates. Air is thus forced into an outlet valve and then into the tire cavity to maintain air pressure within the tire cavity at a desired pressure level. The tube 34 may be replaced by forming an enclosed pumping passageway within the sidewall 18 if so desired (not shown). A passageway if so integrated within the sidewall would function to peristaltic pump air segment-by-segment along the passageway as with the tube embodiment shown.
The tube 34 mounts closely within a groove in the tire and sequentially flattens segment-by-segment as the tire rotates. The segment-by-segment flattening of the tube 34 as the tire 12 rotates operates to pump air which is then directed into the tire cavities 22, 24 to maintain the desired pressure level. A peristaltic pumping system employing a tube within a sidewall groove is also shown in U.S. Pat. No. 8,042,586 entitled SELF-INFLATING TIRE ASSEMBLY incorporated herein by reference in its entirety.
Referring to
The transfer housing 36 is connected to an end of an elongate connecting tube 38. An opposite end of the connecting tube 38 attaches to a control valve assembly 40 including a control valve housing 46 which attaches to the valve stem 42. Seated within the connecting tube 38 proximate the control valve housing 46 is a one-way check valve 44 (
With continued reference to
Attached to mount to the control valve housing 46 in air flow communication with the passageway 48 is a safety relief valve 52 of a type commercially available. The relief valve 52 operates to vent air from the housing passageway 48 when the tire pressure of both tires 12, 14 is at or above a desired preset inflation level. Relief valve 52 is set to open when air pressure within the control valve passageway 48 is above the pressure inflation level desired for the dual tires.
An outlet tube 58 is coupled to the control valve housing 48. Tube 58 is generally T-shaped having a tube segment 54 connecting at a right angle with a linear tube segment 60. A T-shaped air passageway 59 resides within the tube 58, shared by both the tube segment 54 and the linear tube segment 60 as shown. The tube segment 54 has a nut 56 connecting to an elongate second outlet tube 64. The linear tube segment 60 has a threaded coupling 61 that attaches the segment 60 to an elongate, L-shaped first outlet tube 62.
The first outlet tube 62 extends from the control valve housing 46 in a linear path to a right angle bend. From the right angle bend, the tube 62 extends a terminal end 66 through the rim 13 carrying the first tire 12. The tube 62 is thus connected to the tire rim and in air flow communication with tire cavity 22 of the first tire 12. The second outlet tube 64 is coupled by screw thread coupling 56 to the tube segment 54. The second outlet tube 64 extends from the tube segment 54 along an elongate linear path spanning both of the rims 13, 15. At a terminal end, the second outlet tube 64 is coupled to a right angle sleeve 70 by screw coupling 68. The sleeve 70 connects at an opposite end to a rim tube 72 that routes back to a right angle bend 73. The rim tube at bend 73 turns to project through the rim 15. A terminal end 74 of the rim tube 72 is thus positioned in air flow communication with cavity 24 of the second tire 14.
It will be noted from
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.
