Gas pressure driven fluid pump having magnetic valve control mechanism and method

A gas pressure driven fluid pump comprising a pump tank having a liquid inlet and a liquid outlet. A float, carried within the interior of the pump tank, is operable to move between a low level position and a high level position. A snap-acting valve control mechanism uses magnetic interaction to switch between exhaust porting and motive porting. Fluid exiting the pump tank causes the float to fall from the high level position to the low level position due to introduction of motive gas during motive porting. Exhaust porting begins when the float falls to the low level position.

BACKGROUND OF THE INVENTION

The present invention relates generally to gas pressure driven fluid pumps. More particularly, the invention relates to such a pump utilizing a magnetic valve control mechanism which selectively opens and closes gas ports in a snap acting manner.

Condensate removal systems in steam piping arrangements often utilize gas pressure driven pumps that function without electrical power. As described in U.S. Pat. No. 5,938,409 to Radle (incorporated herein by reference), such a pump typically will have a tank with a liquid inlet and a liquid outlet. The liquid inlet and liquid outlet, which are located near the bottom of the tank, will be equipped with an inlet check valve and an outlet check valve to permit liquid flow only in the pumping direction. A pair of interconnected valves control a gas motive port and a gas exhaust port.

The pump operates by alternating between a liquid filling phase and a liquid discharge phase. During the liquid filling phase, the motive port is closed while the exhaust port is open. A float connected to a snap acting linkage rises with the level of liquid entering the tank. When the float reaches a high level position, the linkage snaps over to simultaneously open the motive port and close the exhaust port. As a result, the pump will switch to the liquid discharge phase.

In the liquid discharge phase, steam or other motive gas is introduced into the pump tank through the motive port. The motive gas forces liquid from the tank, thus causing the float to lower with the level of the liquid. When the float reaches a low level position, the linkage snaps over to simultaneously open the exhaust port and close the motive port. As a result, the pump will again be in the liquid filling phase.

While snap acting linkages used in gas pressure driven pumps of the prior art generally have functioned well, there exists room in the art for additional snap acting valve arrangements.

SUMMARY OF THE INVENTION

The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.

In one aspect, the invention provides a gas pressure driven fluid pump. The pump comprises a pump tank having a liquid inlet and a liquid outlet. A float is carried within the interior of the pump tank and moves between a low level position and a high level position, depending upon the fluid level within the pump tank.

A first magnet portion is operatively connected to the float and moves between a first position and a second position as the float moves between its low level position and its high level position. A second magnet portion is operatively associated with the first magnet portion.

The pump also includes a valve assembly connected to the second magnet portion, which is switchable in a snap-over fashion between exhaust porting and motive porting due to magnetic interaction between the first magnet portion and the second magnet portion.

When the first magnet portion is located in its first position, the valve assembly is positioned for exhaust porting. The valve assembly snaps over to motive porting when the first magnet portion reaches its second position. As a result, liquid will be alternatively introduced into and discharged from the pump tank.

In another aspect, the invention provides a snap-acting valve control mechanism for controlling at least one valve. The mechanism includes a first magnet portion that is movable between a first position and a second position. A second magnet portion is operatively associated with the first magnet portion.

The mechanism also includes an actuator connected to the second magnet portion such that movement of the actuator results from magnetic interaction between the first magnet portion and the second magnet portion. When the first magnet portion reaches its first position, the actuator moves the valve to an open position. The actuator moves the valve to a closed position, however, when the first magnet portion reaches its second position.

The invention also includes a method of operating a magnetic snap acting valve actuator assembly. The method comprises moving an annular magnet in a direction substantially parallel to its central axis. This movement of the annular magnet increases the magnetic force exerted on an inner magnet located at least partially within the annular magnet. Continued movement of the annular magnet will continue to increase the magnetic force on the inner magnet until the relative displacement of the two magnets results in the magnetic force snapping over to act in the opposite direction and quickly moving the inner magnet. When the inner magnet is moved, a valve is actuated in a snap over manner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to presently preferred embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not limitation of the invention.

FIGS. 1A–1Dillustrate a pressure driven pump10constructed in accordance with the present invention. As shown, pump10has a tank12defining an interior in which a float14is located. Float14is attached to the end of a float arm16, which is operatively connected to a valve control mechanism18. Valve control mechanism18, in turn, controls the operation of a valve assembly19including a motive valve20and an exhaust valve22.

Valves20and22, respectively, function to introduce motive gas into and exhaust gas out of the interior of tank12based on the position of float14. Toward this end, a motive pipe24is connected between motive valve20and a source of motive gas, such as a source of steam. Similarly, a balance pipe26is connected between exhaust valve22and a suitable sink to which gas inside of tank12can be exhausted. In some cases, for example, balance pipe26can terminate such that the gas will simply exhaust to the ambient atmosphere.

As shown, tank12defines a liquid inlet28through which the liquid to be pumped is introduced. Tank12further defines a liquid outlet30through which the liquid passes when pumped into return line32. Respective check valves34and36are provided at liquid inlet28and liquid outlet30so that the liquid flows in only the desired direction.

When tank12is emptied, float14will fall to the low level position LP shown inFIG. 1A. Upon reaching position LP, mechanism18simultaneously switches motive valve20and exhaust valve22in a snap over manner from motive porting to exhaust porting. During exhaust porting, exhaust valve22is open to allow fluid communication between the interior of tank12and balance pipe26; motive valve20, however, is closed to block fluid communication between motive pipe24and tank12. It should be appreciated by one of ordinary skill in the art that various types of valves could be used for motive valve20and exhaust valve22.

At the beginning of the liquid filling phase, liquid will begin flowing into tank12when the pressure is sufficient to overcome the pressure drop across check valve34. If the pressure of the liquid is high enough, it will continue through check valve36and into return line32. When the back pressure in return line32exceeds the pressure in the interior of tank12, however, the liquid will begin to fill tank12. As the level of the liquid rises, so does float14. As seen inFIG. 1B, however, the positions of motive valve20and exhaust valve22do not change when float14is rising.

When float14reaches position HP, however, as shown inFIG. 1C, mechanism18simultaneously switches motive valve20and exhaust valve22in a snap over manner from exhaust porting to motive porting. During motive porting, motive valve20allows fluid communication between the motive pipe24and the interior of tank12. Motive gas thus introduced into tank12will force the liquid through liquid outlet30and into return line32. In contrast, exhaust valve22is closed during motive porting as shown. Float14drops along with the level of the liquid. As shown inFIG. 1D, however, the positioning of motive valve20and exhaust valve22remains the same until float14reaches position LP. When float14eventually falls to position LP, the pumping cycle will begin again.

The construction of valve control mechanism18will now be described with reference toFIGS. 2A and 2B. Mechanism18contains a fulcrum38about which float arm16is pivotally connected. One of ordinary skill in the art should recognize that there are numerous devices that could be used to pivotally connect float arm16to mechanism18. As shown, for example, mechanism18could include a pair of depending rails40with a pin42extending therebetween. Pin42extends through float arm16so as to pivot at this location. Alternatively, float arm16could pivot from a shaft transversely attached to the interior of tank or using another pivotal connection.

Float arm16is also pivotally connected to a push rod44. As shown, the pivot point between float arm16and push rod44is offset from fulcrum38by a predetermined lateral distance. Thus, rotation of float arm16causes vertical movement of push rod44along its longitudinal axis. The movement of float14from position LP toward position HP moves push rod44in a first direction along its longitudinal axis (downward as shown inFIGS. 1A–1B). As float14moves from position HP to position LP, however, push rod44moves in an opposite direction along its longitudinal axis (upward as shown inFIGS. 1C–1D).

Mechanism18includes a pair of repelling magnets that facilitate snap-over action: an outer magnet46and an inner magnet48. In some embodiments, movement of push rod44along its longitudinal axis causes movement of outer magnet46along a parallel axis. Upon reaching an extreme position, outer magnet46causes movement of inner magnet48along an approximately parallel axis. It will be appreciated that the use of repelling magnets reduces the number of moving parts and linkages relative to spring-type mechanisms. Moreover, the number of friction points is reduced. Thus the use of repelling magnets reduces the potential for failure. Both inner magnet48and outer magnet46could be formed from various suitable materials, such as neodymium iron boron or samarium cobalt. Furthermore, it should be appreciated that attractive magnets may also be used.

A retaining structure50connected to push rod44holds outer magnet46. As can be seen, support structure50has a generally cup-like configuration in this embodiment in which magnet46is inserted. As one skilled in the art will appreciate, structure50and push rod44can be constructed as a unitary member or can be two pieces that are connected together. It should also be appreciated that structure50is preferably formed from a nonmagnetic material, such as aluminum. Outer magnet46moves linearly with the movement of push rod44, which is controlled by the movement of float14. Thus, outer magnet46reaches its extreme positions when float14does the same.

Inner magnet48is attached to an actuator plate52via shaft51, such that movement of inner magnet48also moves actuator plate52. One of ordinary skill in the art should recognize that inner magnet48and actuator plate52can be constructed as a unitary member or can be two pieces that are connected together. It should also be appreciated that inner magnet48could be held within a sheath formed from a nonferrous material, such as copper, aluminum or suitable polymeric materials. The sheath will protect and guide the inner magnet as it may rub against the inner diameter of the outer magnet.

As shown, actuator plate52is in communication with both motive valve20and exhaust valve22. Thus, movement of actuator plate52controls the porting of motive valve20and exhaust valve22. As seen inFIGS. 1A and 1B, motive valve20is closed and exhaust valve22is open when actuator plate52rests on stop54. With actuator plate52in an elevated position, however, motive valve20is open and exhaust valve22is closed, as seen inFIGS. 1C and 1D. Stop54limits downward movement of actuator plate52while upward movement is limited by exhaust valve22in this embodiment. One skilled in the art should recognize that multiple methods could be used for communication between the valves and actuator plate52.

As outer magnet46moves through its range of motion, based upon the position of float14, the relative magnetic force imparted upon inner magnet48changes. When outer magnet46reaches either extreme position (corresponding with either position HP or position LP of float14), the magnetic interaction between outer magnet46and inner magnet48is sufficient to cause repelling movement of inner magnet48.

When float14reaches position LP, the magnetic interaction between outer magnet46and inner magnet48imparts a sufficient downward force on inner magnet48to move inner magnet48in a snap over manner to its exhaust position (actuator plate52resting on stop54). Thus, motive valve20is closed and exhaust valve22is open. When float14reaches position HP, the magnetic interaction between outer magnet46and inner magnet48imparts a sufficient upward force on inner magnet48to move inner magnet48in a snap over manner to its motive position (actuator plate52in an elevated position). Thus, motive valve20is open and exhaust valve22is closed.

Magnets46and48could be configured numerous ways to produce sufficient magnetic interaction to cause snap over movement. As shown, for example, an annular outer magnet46could be used to provide a surrounding magnetic force to move a cylindrical inner magnet48. With this configuration, cylindrical inner magnet48is received within the inner diameter of annular outer magnet46.

In some embodiments, magnets46and48could be configured as planar magnets. For example, magnet48could be configured as a single planar magnet with one or more adjacent planar magnets. Moreover, a guide (not shown) could be used to reduce lateral movement of inner magnet48. Particularly with a guide, a single planar magnet could be used to impart movement of inner magnet48. In addition, one skilled in the art will appreciate that the configuration of structure50may change based upon the configuration of outer magnet46. In other embodiments, valve control mechanism18could be mounted to a vertical cover flange (not shown) using mounts on the side of the pump tank.

The interaction between outer magnet46and inner magnet48during a pumping cycle will now be discussed. When tank12is emptied, float14will fall to position LP. The movement of float arm16causes upward movement of push rod44and outer magnet46. Upon reaching position LP, the position of outer magnet46with respect to inner magnet48causes sufficient magnetic interaction to move inner magnet48in a snap over position to its exhaust position as shown inFIGS. 1A and 3A. In the exhaust position, actuator plate52rests on stop54, thereby placing motive valve20in a closed position and exhaust valve22in an open position. Exhaust valve22thus allows fluid communication between the interior of tank12and balance pipe26while motive valve20prevents fluid communication between motive pipe24and tank12.

As liquid begins flowing into tank12, float14rises. The movement of float arm16causes downward movement of push rod44and outer magnet46as indicated by arrow H inFIG. 3B. As seen inFIGS. 1B and 3B, however, the positioning of inner magnet48remains the same until outer magnet46reaches a position corresponding with position HP of float14. Thus, the position of motive valve20and exhaust valve22also remains the same.

When float14reaches position HP, the position of outer magnet46with respect to inner magnet48causes sufficient magnetic interaction to move inner magnet48in a snap over manner to its motive position as shown inFIGS. 1C and 3C. In the motive position, actuator plate52is elevated, thereby placing motive valve20in an open position and exhaust valve22in a closed position. Motive valve20thus allows fluid communication between the interior of tank12and motive pipe24while exhaust valve22prevents fluid communication between balance pipe26and tank12. When float14eventually falls to position LP, the pumping cycle will begin again.

One skilled in the art will appreciate that the valve control mechanism of the present invention could be utilized in various applications other than a gas pressure driven pump as described above. In such applications, the mechanism could be operated by various devices and mechanisms other than a float (e.g., by hand, electric, pneumatic, etc.). Moreover, it is often not necessary or desirable to attach physically the stem of valve20to plate52. In such embodiments, plate52can push the stem up when plate52rises from stop54. The pressure inside of motive pipe24will close valve20when plate52is resting on stop54.

While preferred embodiments of the invention have been shown and described, modifications and variations may be made thereto by those of ordinary skill in the art without departing from the spirit and scope of the present invention. It should also be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to be limitative of the invention as further described in the appended claims.