BACKGROUND OF THE INVENTION

Maintenance of adequate pressure in pneumatic tires is acknowledged -as a critical requirement. In particular high performance tires used on the wheels of modern aircraft of increased size and weight landing at increased speeds greatly increase the criticality of accurate tire pressure.

In practice, in maintenance of aircraft and other vehicles employing pneumatic tires such as highway trucks, and off the road vehicles it is for the most part difficult and in some cases impossible to provide a regulated source of pressurizing gas. also, high performance tires are often inflated with nitrogen in order to reduce the tendency of tires to oxidize at high temperatures. Nitrogen is further used due to the increased size of its molecule and subsequent reduction in tire leakage. A convenient and economic source of nitrogen is high pressure tanks wherein the delivered nitrogen is regulated from a typical tank pressure of 3,000 P.S.I.G., to required delivery pressure typically 300 P.S.I.G. to each particular tire.

However, regulators are often inaccurate, or fail to control delivery, or in many cases limit the delivery flow to low values requiring excessive time for inflation. Also in many cases, it is exigent to utilize unregulated sources, particularly in the case of secondary tanks filled from a primary source. These tanks in common use are economical, convenient and avoid the complication of an attached regulator. This type of tire filling or pressurization is essentially a cut and try operation. The usual technique involves approaching a desired pressure by initial gauging and filling in small . steps. Since individual filling steps are by "feel", over pressurization can easily occur.

An additional and crucial difficulty in tire overpressure arises from explosive failure of tires under sufficient overpressure. In many cases these explosions have caused serious injury and death to attending personnel.

* In view of the above mentioned difficulties, it is necessary to regulate flow and delivery pressure for each individual tire. In this way correct inflation even where requirements include varying pressure tires can be serviced without adjustment of an individual regulator and tire filling time can be minimized.

These difficulties and safety related difficulties encountered with presently used tire pressurizing valves are essentially overcome through the use of Applicant's invention. As disclosed. Applicant's invention provides a small light weight and economical self-contained pressure and flow limiting valve as a replacement for the conventional tire valve. In use.

the valve of the invention provides pressure relief and limits flow into the tire when .in the relief position through positive shutoff, providing a convenient means for rapidly maintaining tire pressure. from unregulated sources.

It is therefore an object of this invention to provide a pneumatic tire pressurization valve incorporating pressure relief at a predetermined pressure setting along with further overpressure protection through flow limiting and positive shutoff of the pressurizing gas in the valve relief position.

It is an additional object of this invention to provide a pneumatic tire fill valve having size, weight, and cost features which allow permanent mounting on individual tires, thereby providing automatic control of tire pressurization without the need for a separate tire gauging operation.

It is a further object of this invention to provide a small, lightweight and economically designed tire fill valve directly replacing the individual original tire valve, wherein correct tire pressure can be insured when the tire fill gas source is of substantially greater pressure and flow capacity.

It is yet an additional object of this invention to provide increased safety for maintenance personnel engaged in pressurizing high pressure pneumatic tires from sources having excessive pressure and flow capacity through the use of a pressure and flow limiting valve continuously attached to the tire.

SUMMARY OF THE INVENTION:

The invention disclosed herein is a small, lightweight, economical tire fill valve of such size and weight that it can be permanently attached to the rim of a tire mounted wheel. Pressurizing gas from a source of high pressure and/or flow capacity is admitted at the valve inlet through the usual spring loaded poppet type inlet valve commonly known to the pneumatic industry as a Schrader valve. Pressurizing gas, admitted through the Schrader valve by depressing its inlet or operating rod by a typical air chuck, passes through a flow limiting orifice containing a flow actuated poppet before entering a pressure sensitive chamber. The pressure sensitive chamber is in constant fluid communication with the tire interior. Also in fluid communication with the pressure sensitive chamber via a multiplicity of orifices having a semicircular segmental cross section, is a valve disk cooperating with a valve seat on the exit side of the chamber exhaust passage. The valve disk is force biased by a series of spring washers having a preload force. The spring washers also limit lifting travel of the valve disk at a predetermined chamber pressure.

When the pressure sensitive chamber reaches a pressure wherein the valve disk force approaches that of the spring washers, vertical movement or lifting of the valve disk allows gas flow from the chamber to exit the valve through an additional multiplicity of ^" segmental relief passages and/or vents arranged in a circular pattern circumferential of the inlet or Schrader valve.

In operation, as the tire pressure reaches the value determined by the force balance system, consisting of the valve disk and the spring washers, any increase in tire pressure above a predetermined value is prevented by disc lift and venting the fill gas. In cases of gas sources having extremely high gas delivery, overpressurization of the pressure sensitive chamber is prevented since excess flow through the flow limiting orifice is prevented by positive shutoff of a flow sensitive poppet contained in the orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent upon reading the following detailed description and indicated reference to the drawings, in which:

Figure 1 is a side view of the finished valve, shown essentially full size. In particular the upper or inlet valve, and lower or tire attachment adapter are shown along with a hexagonal installation shoulder.

Figure 2 is a cross-sectional view of the valve of the invention along the line 2-2' of Figure 1 (inlet cap omitted) . Figure 1 Particularly showing the valve of the invention during tire fill or non-relief position.

Figure 3 is a partial section at the line 2-2 of Figure 1, showing the valve of the invention in overpressure and overflow relief, particularly showing the flow sensitive poppet in positive shutoff.

Figure 4 is an additional section along the lines 4-4 of Figure 2, particularly showing the semi-circular segmented or arcurate upper relief passages of the valve of the invention.

Figure 5 is a section of the valve of the invention along the line 5-5 of Figure 2, particularly showing the semi-circular segmented or arcurate lower relief ports.

Figure 6 is a partial enlarged section of the valve of the invention along line 2-2 of Figure 1, particularly

showing the gas inlet adapter and flow sensitive poppet, in a fill or non-relif position.

While the pneumatic pressurization valve of this invention will be described in connection with a preferred embodiment, it is understood that the preferred embodiment is not intended to limit the invention to that embodiment. On the contrary it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

With particular reference to Figures 1 and 2, there is shown a pressure and flow relieving tire inflation or pressurization valve 2 of the invention having a gas 5 pressurization inlet 1 and a tire adapter and outlet and 3. The valve also incorporates a hexagonal section 6 having safety or retention wire holes or ports 9 in keeping with commonly used wire antiturn techniques in use in the aircraft and/or automotive 10 industries.

With particular reference to figure 2, the tire pressurization and relief valve of the invention 2 comprises outer shell or housing 5. Internal of the outer shell or housing at its upper end is a hex head

15 portion 6 suitable for proper installation, and a gas inlet adapter 17. The outer housing 5 further includes at its lower end a threaded outlet or tire adapter 7 having an outlet port 14 suitable for direct piounting on the rim inlet of the wheel mounting the

20 pressurized tire. Intermediate of the outlet and gas inlet adapter is a valve spool 29 incorporating a spool spring chamber and/or relief passage 35 containing an annular spring and/or spring washers 44 and an annular valve disk 46. The spring washers and

:25 valve disks are concentric with a circumferentially ^' disposed around a lower portion of the gas inlet adapter 17.

The lower . portion of the valve spool 29 further incorporates a plurality of segmental semi-circular 30 flow passages or orifices 41 each having a seat 45 in sealing cooperation with a concentric valve disk seal 47.

The lower end of the lower relief passages 41 defined by the valve spool 29 terminate in a pressure-sensing chamber 42 further defined by the lower portion of the valve spool 29 and the upper surface of a deflector disk 32. The lower surface of the pressure sensing chamber 42 includes tire fill ports 33. Fill ports 33 fluid communicate the pressure sensing chamber 42 and the interior of the tire to be filled via the valve exit port 14. Suitable pressure seals 43 are positioned between the valve housing 5 and lower corners of the valve spool 29, and deflector disc 32.

As indicated above, internal of and surrounded by the hexagonal housing head 6 and valve spool 29 is a gas inlet adapter 17. The adapter includes the valve inlet port 8

having an external thread 10 for incorporation of a dust cover or additional leak preventing cap 4 (reference Figure 1) . The internal port 8 threadably engages a tire fill valve of a conventional type commonly known as a "Schrader" valve having its inlet adjacent the inlet port 8 and its outlet internal of the gas inlet adapter flow passage or cavity 18. The lower end of the flow passage 18 defines and/or is terminated by a control orifice 26 thereby fluid communicating the passage or cavity 18 and the pressure sensing chamber 42.

A flow sensitive poppet 19 is mounted in the adapter passage 18. The poppet stem 21 is centrally maintained in longitudinal alignment with the lower base 23 of the inlet adapter passage 18. A conical spring 25 provides alignment and vertical preload

force to the poppet 19, maintaining the poppet closure end 27 above cooperating flow shutoff seat 28.

Also internal of the housing hexagonal head is a plurality of concentrically disposed fill gas exit ports 38 each having a semi-circular arc like cross section. The relief ports 38 fluid communicate the spool spring chamber with ambient air. An annular circular dust cover 39 of flexible elastomeric material such as natural rubber or neoprene provides protection from external contamination of the ports 38, readily allowing venting of the pressurizing pressure gas during relief operation of the valve.

In operation gas from a high pressure and/or high capacity source is introduced through a conventional air chuck (not shown) having a deflector tongue for depressing the inlet or Schrader valve actuating pin 22. As those skilled in the art will readily recognize, operation of the Schrader valve is such that depressing the- pin 22 moves the lower member or poppet 24 vertically downward opening a concentric port internal of the Schrader valve 20 (not shown), admitting pressurized fill gas to the upper end of gas inlet adapter flow passage or chamber 18. Under fill conditions at pressures below valve calibration as shown in Figure 2, the pressurization gas flows through the chamber 18, shutoff seat 28, and the flow limiting orifice 26, into the pressure sensing chamber 42, through the deflector disk fill ports 33 and into the tire to be inflated through the exit port 14.

At the completion of the filling process, or for any other reasons when the pressure in chamber 42 reaches a value which acts on the underside of the valve disk

46 via the lower relief ports 41 and the valve spool 29 to exceed the predetermined preload of the valve disk springs 44, the disk lifts, as indicated in the right-half portion of Figure 3, allowing relief flow of the pressurizing gas to exit the valve via the spool spring chamber 35 and upper relief port 38. As discussed above, the flexible dust seal 39 is easily deflected by the exiting gas and as shown in the right-half of figure 2 allows easy venting. Venting of the fill gas. under relief conditions limits the pressurization ' of the tire being filled to a predetermined value. Typically, fill pressure is limited to i.e., the valve relief pressure is 300 P.S.I.G.

A highly important feature of the disclosed invention arises from the fact that under conditions where the fill source pressure and/or capacity for one reason or another is a multiple or even an order of magnitude greater than the desired tire maximum, venting of a conventional relief device would still result in over pressuring of the tires since flow through the relief vents would not limit flow through the pressure sensitive chamber sufficiently to prevent overpressure from existing at the tire inlet or valve exit port 14. However, applicant has discovered that inclusion of a flow sensitive poppet 19, maintained in an open or flowing position as shown in Figures 2 and 6, where flow is maintained through valve seat 28 when flow sensitive poppet 19 is held in its open position through preload or bias force of 25, controls tire filling gas flow through said seat 28 for both relief and normal flow conditions of the valve 2.

In operation, should fill pressure in chamber 42 exceed a predetermined relief pressure, venting fill gas through ports 38 reduce filling gas pressure entering the tire at the valve of exit port 14. However if venting through ports 38 is insufficient to hold pressure in chamber 42 to a predetermined value, typically 20% in excess of the desired tire pressure, poppet 19 contained in the gas inlet adapter internal cavity 18, due to flow induced pressure drops across the poppet head 30, moves downward thereby contacting shutoff seat 28 and terminating flow into the tire through exit port 14. Control of shutoff motion and quantity of flow through shutoff seat 28 by poppet 19 is aided by peripheral grooves 31 in the poppet head 30.

Thus it is apparent that there has been provided in accordance with the invention the tire fill valve that fully satisfies the objects, aims and advantages as set forth above. While the tire fill valve disclosed here has been described in conjunction with specific embodiments thereof, it is evident that in the alternatives modifications end variations will be apparent to those skilled in the art in the light of the foregoing description. Accordingly it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims.