Tapered needle plug for bleed port on float operated pneumatic valve assembly

A float operated liquid level switch having a body, a float assembly, a switch magnet, and a needle plug. The float assembly may be pivotally attached to the body at a pivot axis. The float assembly may have a first end and a second end opposite the first end, where the pivot axis is located between the first end and the second end. The float assembly may further comprise a float attached to the first end and a float magnet attached to the second end, such that raising the float causes the float magnet to lower and lowering the float causes the float magnet to rise. The switch magnet may be responsive to movement of the float magnet, and the needle plug may be responsive to movement of the switch magnet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tapered needle plug for a bleed port on a float operated pneumatic valve assembly for a pneumatic operated liquid level switch for tanks and vessels.

2. Description of the Related Art

There are a number of existing devices that include float operated valves. In each case, when the liquid level rises or falls in a tank or vessel, a float shifts a pneumatic valve to one of two positions. Some existing devices couple the float to the pneumatic valve using a magnet couple while others use mechanical linkage.

Some existing devices control the pneumatic valve by a pad or flap. Large forces are required to seal such a pad or flap, requiring the use of a powerful magnet where magnet coupling is used.

Based on the foregoing, it is desirable to provide a float operated pneumatic valve utilizing a tapered needle plug instead of a pad or flap. This would reduce the force needed to seal the port, which in turn makes the pneumatic valve more reliable and allows for lower operating specific gravities. It also means the coupling used to connect the float to the valve does not have to supply as much force, which makes for more coupling options, such as a weaker magnetic coupling.

Some existing pneumatic conical or tapered valves with a magnetic switch are direct acting, such as seen in Felgote (U.S. Pat. No. 2,893,427). It is desirable to provide a magnetic opposing pole snap switch with a block and bleed valve arrangement.

It would also be desirable to provide a tapered needle plug for a bleed port on a float operated pneumatic valve assembly wherein a block and bleed valve is externally adjustable.

SUMMARY OF THE INVENTION

In general, in a first aspect, the invention relates to a float operated liquid level switch having a body, a float assembly, a switch magnet, and a needle plug. The float assembly may be pivotally attached to the body at a pivot axis. The float assembly may have a first end and a second end opposite the first end, where the pivot axis is located between the first end and the second end. The float assembly may further comprise a float attached to the first end and a float magnet attached to the second end, such that raising the float causes the float magnet to lower and lowering the float causes the float magnet to rise. The switch magnet may be responsive to movement of the float magnet, and the needle plug may be responsive to movement of the switch magnet.

The switch magnet may be responsive to movement of the float magnet such that lowering the float magnet causes the switch magnet to rise and raising the float magnet causes the switch magnet to lower. Likewise, the needle plug may be responsive to movement of the switch magnet such that raising the switch magnet causes the needle plug to lower and lowering the switch magnet causes the needle plug to rise. Raising the float may cause the needle plug to lower and lowering the float may cause the needle plug to rise.

The switch magnet may be housed within the body. The float operated liquid level switch may further comprise a block and bleed valve controlled by the needle plug. The block and bleed valve may be a pneumatic valve.

In a second embodiment, a float operated liquid level switch comprises a body, a float assembly, a switch magnet assembly, a needle valve, and a block and bleed valve. The float assembly may be pivotally attached to the body at a pivot axis. The float assembly may have a first end and a second end opposite the first end, where the pivot axis is located between the first end and the second end. The float assembly may further comprise a float attached to the first end and a float magnet attached to the second end, such that raising the float causes the float magnet to lower and lowering the float causes the float magnet to rise. The switch magnet assembly may be pivotally attached to the body via a pivot shaft. The switch magnet assembly may comprise a first end and a second end opposite the first end, where the pivot shaft is located between the first end and the second end. The switch magnet assembly may further comprise a switch magnet attached to the first end and located proximate the float magnet, where the switch magnet and the float magnet have like poles such that they repel each other. The needle valve may comprise a needle plug, where the needle plug is attached to the second end of the switch magnet assembly. The block and bleed valve may be controlled by the needle valve.

The switch magnet assembly may be housed within the body. The block and bleed valve may have a seat assembly that is externally adjustable. The block and bleed valve may be a pneumatic valve.

DETAILED DESCRIPTION OF THE INVENTION

The devices and methods discussed herein are merely illustrative of specific manners in which to make and use this invention and are not to be interpreted as limiting in scope.

While the devices and methods have been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the construction and the arrangement of the devices and components without departing from the spirit and scope of this disclosure. It is understood that the devices and methods are not limited to the embodiments set forth herein for purposes of exemplification.

In general, in a first aspect, the present invention relates to a pneumatic operated liquid level switch assembly10for tanks and vessels used in a wide variety of industrial applications.

As seen inFIGS. 1 through 3, a float12may be in fluid communication with liquid1in a tank or vessel (not shown) and will move down when the liquid level decreases, as shown by arrow26, or up when the liquid level increases, as shown by arrow28. The float12may pivot around a pivot axis14. At the opposite end of the pivot axis14may be a float magnet16. Movement of the float12may result in reciprocal movement of the float magnet16. The switch10may include a switch body48near the float magnet16. Within the switch body48may be a switch magnet18, which generates repelling magnet forces. The switch magnet18may revolve around a pivot shaft20which translates into movement of an arm17to move a needle plug22. The needle plug22may be part of a valve seat assembly24, which controls a block and bleed valve assembly30.

The block and bleed valve assembly30, shown in a cut-away view inFIG. 4, may be a pneumatic valve assembly. A diaphragm shaft or pin15may be movable within a chamber in the body of a valve assembly30. The valve assembly30may be a two position three-way valve. The valve assembly30may be supplied with pressurized air or other pressurized gas through an inlet port36. An upper seal and a diaphragm40each extend radially from the diaphragm pin. The inlet port36is in fluid communication with a chamber11that communicates with a bleed port13in a valve seat assembly24.

The diaphragm40has a top side and an opposed bottom side. When the bleed port is blocked by the tapered needle plug22, gas flowing through the inlet36may pressurize both the top side and bottom side of the diaphragm40. The bottom of the diaphragm40may have a larger surface area than the top. The larger surface area provided by the bottom of the diaphragm40may force the diaphragm40upward, shifting the diaphragm and the pin15up and shifting the diaphragm40into the diaphragm seat42. This may seal off the lower seat42and at the same time open up the upper seat44, thereby connecting the outlet port35to the exhaust port37and blocking the inlet port. This would be considered one position of the two position valve.

Movement of the needle plug22by movement of the switch magnet18may move the valve to an alternate position. When the bleed port is open by retraction of the tapered needle plug22by moving the tapered needle away from the bleed port, the bottom of the diaphragm40may be depressurized. Since the top of the diaphragm40continues to receive pressured air from the gas through the inlet port36, a positive force may be created in the downward direction, shifting the diaphragm40and pin15downward and the upper seal38into the upper seat44. This may seal the upper seat44and open the lower seat thereby connecting the inlet port to the outlet port35and blocking the exhaust port37. This would be considered position two of the two position valve.

An optional externally adjustable seat assembly (not shown) may reside within an optional threaded opening (not shown) in the valve portion30. The seat assembly may have external threads that mate with threads on the valve portion30. Rotation of the seat assembly may cause advancement or retraction of the seat assembly within the valve portion30.

Whereas, the devices and methods have been described in relation to the drawings, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.