BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to air vent valves intended to relieve vacuum developed in conduits, while also serving as check valves preventing elevated pressures from propelling fluids past the valve. A principal application of the invention is for vacuum relief of domestic sewage piping systems in residential, commercial, industrial, and institutional buildings. Of course, any conduit system requiring the above aspiration scheme may utilize the invention.

2. DESCRIPTION OF THE PRIOR ART Domestic sewage piping systems usually have one or more conduits open to the atmosphere, for relieving vacuum conditions which would otherwise disrupt effective evacuation of wastewater. In most buildings, one or more such conduits extend through the roof and open above the building.

At different times, both vacuum and elevated pressures can exist within a sewage system. Vacuum, or pressures below ambient pressures, can prevent wastewater from being evacuated. High pressures, which could arise from decomposing organic materials, would not ordinarily interfere with evacuation of wastewater from the building, but can enable objectionable, malodorous gasses to enter occupied spaces if not conducted away therefrom. The open vent pipe ordinarily employed both relieves vacuum and also vents objectionable gasses from the building.

It would be possible to connect a unidirectional check valve to a domestic plumbing wastewater system in place of the permanently open conduit conventionally employed. Any valve which admits ambient air into the plumbing system while preventing noxious or objectionable vapors from entering occupied spaces would achieve the desired flow scheme, but is potentially subject to problems which can plague non- spherical valves. One problem is that non-spherical valves may be broad surfaces which can accumulate moisture and other substances which can cause the valve to stick to its seat. Light conditions of vacuum might then be unable to open the valve. Another problem is

that if a non-spherical valve mis-aligns with its seat, it may potentially fail to seat properly. This could allow objectionable gasses to pass to occupied spaces.

The prior art has proposed valves for relieving vacuum while preventing discharge of gasses in the opposite direction. United States Patent Number 3,863, 671, issued to Bernard Heimann on February 4, 1975, shows a valve for controlling vacuum wherein a counterweight and lever are connected to the valve.

The present invention operates independently of and lacks any counterweight and lever.

United States Patent Number 4,142, 645, issued to Donald G. Walton on March 6,1979, describes a ball valve utilized for maintaining vacuum conditions in home canning operations. The ball vents ambient gasses from a receptacle responsive to connection to a source of suction. By contrast, the present invention is a self-contained assembly wherein the conduit to which it is connected provides both vacuum and also elevated pressures. The novel valve relieves vacuum prevailing in the conduit to which it is connected, while preventing elevated pressures therein from discharging fluids past the valve. The valve of Walton cannot

relieve vacuum developed within the container associated with his valve.

United States Patent Number 4,250, 360, issued to Gustav E. Svensson on February 10,1981, shows a valve operated by tilting or acceleration of the valve housing. Tilting and acceleration cause the valve to overcome resistance of a spring biasing the valve in the closed position. By contrast, the present invention does not rely upon tilting or acceleration of the housing, and does not require a spring.

United States Patent Number 4,806, 082, issued to Jacob W. Schenk on February 21,1989, sets forth a valve assembly incorporating two valves each acted upon by its own spring. The present invention requires but one valve and requires no springs.

United States Patent Number 4,991, 623, issued to Kurt S. B. Ericson on February 12,1991, shows an automatic valve assembly wherein the valve is a disc.

By contrast, the valve of the present invention is a rigid sphere or ball.

United States Patent Number 5,033, 504, issued to Dieter H. F. Kallenbach on July 23,1991, shows a relief valve which utilizes a flexible diaphragm. The

present invention utilizes a ball as the valve, and does not have a flexible diaphragm.

United States Patent Number 5,105, 848, issued to Dieter H. F. Kallenbach on April 21,1992, sets forth an automatic relief valve which also utilizes a flexible diaphragm absent in the present invention.

The present invention has a spherical valve which overcomes problems of non-spherical designs.

United States Patent Number 5,419, 366, issued to Ian F. Johnston on May 30,1995, shows a valve assembly wherein the valve is an elastomeric diaphragm. By contrast, the valve of the present invention is spherical, which design avoids problems associated with non-spherical designs.

United States Patent Number 6,234, 198, issued to the applicant on May 22,2001, shows a valve assembly having two communicating passageways demarked by a valve seat having a ball constrained to move only vertically above the valve seat. The first passageway communicates to the open atmosphere and with the valve from below the valve seat. The second passageway communicates with the valve from above the valve seat and with the associated vessel. The present invention offers an improved valve seal by providing an O-ring at

the perimeter of the valve seat, thereby providing a tighter seal when the valve is in the closed position..

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.

SUMMARY OF THE INVENTION The present invention sets forth an uncomplicated valve suitable for relieving vacuum prevailing within a vessel, and which further prevents elevated external pressures from propelling fluids into the vessel. The novel valve has only one moving part, which is a ball or sphere, and requires no additional apparatus such as springs, counterweights, or any other apparatus connected to the valve to move, guide, or constrain the valve to achieve successful operation. Valve opening is responsive purely to relative pressure between the vessel to which the valve is connected and the open ambient atmosphere. Fluid flow is arranged so that maintaining the valve in the closed position utilizes gravity rather than requires overcoming gravity, while enabling the valve to open responsive to vacuum developed within the associated vessel.

Other advantages of the present invention assure appropriate valve sealing. Radial symmetry of the

spherical shape of the valve provides ability to resist failure to seat due to misalignment of the valve and its valve seat. This promotes effective valve sealing.

Another characteristic of the spherical shape, taken together with configuration of the valve seat, is that contact between the valve and its seat occurs along a circular line. This limited contact avoids a sticking effect which could occur due to accumulation of liquids and semi-solids. Such an occurrence could potentially cause the valve to adhere to the seat, thereby resisting opening responsive to conditions of light vacuum. The ball design assures that the valve will open responsive to low levels of vacuum prevailing in the pipe or vessel onto which the valve is installed.

The novel valve is highly suited to solving the problems of domestic sewer piping systems, wherein vacuum must be relieved while sewer system gasses must be prevented from entering occupied spaces.

Incorporation of the novel valve eliminates the need for extensive piping, roof penetrations, and other disruptions to a structure associated with air vent pipes. The novel valve is free of complicating structure which could fail by clogging, wearing out, corroding, binding, going out of adjustment, or in any

other similar way. It would be highly practical to connect one or more of the novel valves to a plumbing system as an alternative to providing an equal number of vent pipes.

The novel valve is readily formed from three parts, each one of which can be molded from inexpensive components such as plastic. The valve assembly has a housing formed in two parts which are assembled over the valve member, which is a ball. One end of the housing is threaded, so that the valve can be manually threaded to a threaded conduit of piping systems.

Accordingly, it is one object of the invention to provide a valve which both relieves vacuum developing within an associated vessel and also prevents fluids from escaping from the vessel due to relatively high pressures within the vessel.

It is another object of the invention to eliminate auxiliary apparatus which moves, guides, or constrains the valve.

It is a further object of the invention to eliminate need for extensive vent pipes from domestic sewer piping systems.

Still another object of the invention is to provide valve structure which overcomes problems of

clogging, wearing out, corroding, binding, and going out of adjustment.

An additional object of the invention is that the valve respond only to pressures within the vessel which are either high or low relative to ambient atmospheric pressures.

Yet another object of the invention is to provide an uncomplicated valve assembly which can be readily and inexpensively fabricated from inexpensive materials.

Still another object of the invention is to be able to install the novel valve manually to a piping system.

Yet a further object of the invention is that the valve be urged into the closed position both by gravity and by pressure differentials.

An additional object of the invention is to overcome potential sticking of the valve in the closed position, and to prevent potential misalignment between the valve and its seat.

It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is

inexpensive, dependable and fully effective in accomplishing its intended purposes.

These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: Fig. 1 is a side elevational, diagrammatic view of an embodiment of the invention, shown mostly in cross section, illustrating static conditions with the valve in the closed position.

Fig. 2 is a side elevational, diagrammatic view similar to Fig. 1, showing pressure and fluid flow conditions urging the valve into an open position.

Fig. 3 is an exploded, side elevational view of a preferred embodiment of the invention.

Fig. 4 is an environmental, side elevational view of one embodiment of the invention, shown mostly in cross section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 of the drawings schematically shows the principle of operation of novel combined vacuum relief and pressure containing valve assembly 10. Valve assembly 10 relieves vacuum developing within an associated vessel (see Fig. 4), such as a pipe or tank, and contains elevated pressures developing within the vessel. Valve assembly 10 comprises a housing 12 having an internal passage divided into a first passageway 14 and a second passageway 16 which second passageway 16 communicates with passageway 14. A valve seat 18 formed in housing 12, the upper perimeter being surrounded by an 0-ring 19, demarcates first passageway 14 and second passageway 16.

A spherical valve 20 occupies first passageway 14.

Housing 12 is configured to entrap valve 20 therewithin. Valve 20 is free floating within housing 12, being unencumbered by structure attached thereto.

Valve seat 18 and O-ring 19 are dimensioned and configured to constrain valve 20 from entering second passageway 16. Valve seat 18 and 0-ring 19 close communication between first passageway 14 and second passageway 16 when valve 20 seats against O-ring 19.

Valve seat 18 has a circular opening 22 bounded by an

upright interior surface disposed at a perpendicular angle to upper surface 24 of wall 26 forming valve seat 18. As a consequence, valve seat 18 is configured such that valve 20 establishes contact with valve seat 18 solely along O-ring 19.

Second passageway 16 communicates to the open atmosphere outside housing 12 and with valve 20 from below valve 20, with valve assembly 10 in the upright position depicted in Fig. 1. This upright position is that in which valve assembly 10 is operable and is installed to an associated vessel wherein interior vacuum is relieved. First passageway 14 is disposed to communicate with valve 20 from above valve 20.

Passageway 14 extends and terminates below valve 20 when valve assembly 10 is in the upright position wherein valve 20 is located above valve seat 18 and O- ring 19.

Fig. 1 illustrates valve assembly 10 in the closed position, which position will occur whenever fluid pressure within passageway 16 does not exceed fluid pressure within passageway 14. This condition encompasses both equal pressures and also relatively higher pressure prevailing within passageway 14. High pressure is indicated representatively by arrows 28.

Arrows 28 indicate the general direction in which fluid would flow if valve 20 were either open or absent, given relatively higher pressure in passageway 14.

Fig. 2 shows opening of valve 20, which occurs whenever pressure prevailing within passageway 16 exceeds that of passageway 14. Valve 20 is lifted from contact with valve seat 18 and O-ring 19. Fluid proceeds in the direction of arrows 30. It will be appreciated that first passageway 14 and second passageway 16 are dimensioned and configured to maintain valve 20 in an open position solely by relatively low pressures prevailing within first passageway 14 when relatively high pressures prevail within second passageway 16, and to maintain valve 20 in a closed position solely by gravity. The same configurations contribute to forces urging valve 20 into the closed position of Fig. 1 when relatively high pressures prevail within first passageway 14 and relatively low pressures prevail within second passageway 16.

Optionally, housing 12 has threads 32 capable of enabling valve assembly 10 to be threaded to a vessel having matingly compatible threads (not shown).

Valve assembly 10 may be fabricated in any suitable way. For applications in domestic sewer systems, valve assembly 10 may be molded from a plastic material such as polyvinyl chloride. Housing 12 is preferably formed in two separate pieces which are united after valve 20 is placed over valve seat 18.

This is shown in Fig. 3, to which attention is now directed.

In the preferred embodiment, valve assembly 110 is formed in three parts, including a base 102, a cap 104, and ball valve 120. Base 102 incorporates a valve seat 106, being surrounded at its upper perimeter by an O-ring 108. Air passage 116 is formed between walls 122,124 of base 102. In the embodiment of Fig. 3, air passage 116 extends to the side walls of base 102. Air passage 116 is closed at the bottom by a floor panel 118 which extends to the inner circumferential surface 126 of circumferential wall 128 of base 102. Floor panel 118 is solid except for air passages 130 which enable fluid communication between passageway 114A of base 102 and passageway 114B of cap 104 when cap 104 is installed on base 102.

Cap 104 has lateral breather openings 132 which open air passage 116 to the open atmosphere when cap

104 is installed on base 102. Cap 104 is lowered over base 102 when being installed until flange 134 of cap 104 abuts flange 136 of base 102. Upwardly projecting pins 138 are received in cooperating openings (not shown) formed in cap 104 to assure operable alignment of breather openings 132 with air passage 116 during installation. It would be evident to one skilled in the art that mated grooves and projections in the inner and outer faces of cap 104 and base 102 could also be used to align breather openings 132 with air passages 116. Downwardly projecting prongs 140 collectively form a cage constraining ball valve 120 to move only vertically above valve seat 106 when valve assembly 10 is in the vertical orientation shown in Fig. 3. This function is performed by fins projecting upwardly from wall 26 in the embodiment of Fig. 1. Vertical orientation of valve assembly signifies that axis 142 of valve seat 106 is vertically oriented. Ball valve 120 is thus constrained against moving within passageway 114B to a position from which it cannot seat.

Cap 104 may be detachably fixed to base 102 by friction fit if desired. Alternatively, cap 104 may be glued or welded to base 102.

Fig. 4 shows a representative application of the invention. Valve assembly 10 is mounted on a vertical extension 4 of a pipe 2. Pipe 2 contains water 8 flowing in the direction of arrow A. Flow induces a vacuum to develop in pipe 2. Valve assembly 10 relieves this vacuum by admitting air from the atmosphere outside pipe 2. Because valve assembly 10 prevents objectionable gasses from passing from inside pipe 2 to the atmosphere around pipe 2, it is feasible to locate valve assembly 10 at any convenient point inside a residence or other building served thereby.

The conventional vent pipe typically penetrating the roof is eliminated.

It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.