FIELD OF THE INVENTION

A check valve for water pipes which permits flow in a forward direction and prevents flow in the opposite direction, where the pressure required to open the valve is adjustable.

BACKGROUND OF THE INVENTION

Check valves permit fluid to flow in one direction in a conduit but prevent flow in the opposite direction. Check valves are required to prevent backflow into a conduit. The necessary basic capability for a check valve is to have a valve seal which opens when the flow is from upstream to downstream, but to close when downstream pressure exceeds upstream pressure to prevent flow upstream past the check valve. One pervasive problem with check valves is that when systems are idling or shutting down, the pressure differential between upstream and downstream may approach zero, resulting in the check valve fluctuating between open and closed and allowing undesired backflow.

A known solution for dealing with the above-described situation is to use a spring or magnet to maintain the valve closed until the pressure differential between the upstream pressure and downstream pressure reaches a predetermined value which is sufficient to overcome the spring tension or the magnetic force and allow the valve to open. However, with devices which only utilize a spring for valve closure the valve may open gradually depending upon the spring constant. If the differential is close to the predetermined value, the valve might only open partially. In addition, check valves utilizing only spring force for closure require increasing pressure to open past the initial cracking pressure, which is generally not a desirable feature of a check valve.

Another issue which exists with check valves which open at fixed and predetermined values is that for some applications the differential pressure may change over time, but the valve will continue to open at the same value of differential pressure. This may result in undesired flow situations, where either backflow occurs when not desired, or the upstream pressure required to open the check valve becomes greater than desired. In an effort to resolve this problem, some check valves, specifically center poppet valves, allow the adjustment of spring tension by tightening or loosening a screw in the middle of the valve. However, for this type of valve, the valve cannot be permanently installed until the spring tension has been adjusted to the desired tension, which often requires multiple spring adjustments, assembly and disassembly in order to obtain the desired result.

The current adjustable spring check valves, as with the non-adjustable spring valves, have spring tensions which increase as the valve opening increases, resulting in restricted flow. Moreover, the center poppet design has webbing which supports the poppet, which can trap debris, further reducing the flow and keeping the valve from fully closing. The known valves having magnetic closure have a non-adjustable gate retention force.

SUMMARY OF THE INVENTION

Embodiments of the presently disclosed apparatus answers the need identified above. Embodiments of the present invention do not rely upon springs to achieve a desired opening pressure or vacuum, but rather upon a magnet set, where the force which must be overcome for the valve to open is the attractive force between either a pair of opposing magnets or a single magnet and a ferromagnetic magnetic member, where the attractive force may be adjusted by increasing or decreasing the distance between the two.

One embodiment of the valve has a body having an inlet port, an outlet port, and a flow passage there between. The valve and its components are so constructed and arranged such that the valve closes to prevent a reverse flow of a fluid from the outlet port to the inlet port, and the valve opens so as to permit a forward flow of the fluid from the inlet port to the outlet port. However forward flow only occurs under a positive forward differential pressure having a magnitude equal to or above an adjustable value. This feature prevents forward flow at differential pressures lower than the adjustable value.

An embodiment of the check valve has a valve seat in the flow passage through which the fluid will flow and a valve closure carrying a valve seal which is complementary to the valve seat. The valve closure may be pivotally attached to the body inside the flow passage, where the valve closure is configured to pivot against and seal against the valve seat thereby preventing the reverse flow of the fluid when the valve closure is in a closed position. The valve closure is configured to pivot away from the valve seat thereby permitting the forward flow of the fluid when the valve closure is in an open position.

Embodiments of the check valve also have a magnetic set which develops, when the valve closure is in the closed position, where a retention force that must be overcome for the valve closure to move to the open position. The magnet set comprises a first magnet and a ferromagnetic member, which may be a second magnet. In this embodiment, the magnet has a first magnetic pole and second magnet has a second magnetic pole, where the first magnetic pole and the second magnetic pole are disposed in attractive relationship when the valve closure is in the closed position. The magnitude of the positive differential pressure required for the valve to open may be manually adjusted by changing the distance separating either the first magnet and a non-magnet ferromagnetic member or the distance between the first magnetic pole of the first magnet and the second magnetic pole and the second magnet. For embodiments utilizing a non-magnet ferromagnetic member, acceptable materials include iron, cobalt, nickel, steel, manganese, gadolinium and lodestone.

In one embodiment of the check valve the first magnet is disposed within a first compartment adjacent to the flow passage. A shaft penetrates the valve body through an exterior wall and extends into the first compartment, where the first magnet is attached to the shaft. The first magnet may be moved within the first compartment by movement of the shaft either towards the second magnet (or ferromagnetic member) or away from the second magnet (or ferromagnetic member), such movement adjusting the magnitude of the positive differential pressure required for the valve to open. The shaft may be rotatable such that rotation of the shaft translates the first magnet within the first compartment toward the water-tight seal or away from the end of the first compartment adjacent the valve seat. The first magnet may also be contained within a water-tight magnet carriage which is disposed within the first compartment, where an end of the shaft is attached to the magnet carriage. An opposite end of the shaft may extend outside of the valve body and a screw knob disposed on the opposite end of the shaft.

The valve closure may comprise a gate body having a first end pivotally attached to an inside portion of the valve body, the gate body also having a second end opposite the first end, where the second end comprises the second magnet or ferromagnetic member.

The interior of the valve body may also have an inner recess into which the second end of the gate body may be disposed during a forward flow of the fluid. In this configuration embodiments of the valve may allow the flow passage to be fully open during a full forward flow of the fluid.

In some embodiments of the check valve, for example the two-inch valves, the positive differential pressure required to allow the valve to open may be adjusted within a range of 5-15 psi based upon the relative distance between the first magnet and the second magnet (or ferromagnetic member). Nickle plated neodymium (N52 strength) magnets are acceptable for embodiments of the check valve.

