US3566912A

US3566912A - Magnetically biased valve device

Info

Publication number: US3566912A
Application number: US760020A
Authority: US
Inventors: Evald Dunkelis
Original assignee: GPE Controls Inc
Current assignee: GPE Controls Inc
Priority date: 1968-09-16
Filing date: 1968-09-16
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02
Also published as: NL6913989A; FR2018147A1; NO126812B; JPS5022252B1; ES370864A1; DE1946854A1

Abstract

A pressure responsive valve having a single tank opening and single main pallet which provides pilot operation to relieve both overpressure and vacuum conditions within the tank. Also disclosed are features provided to improve operation of certain portions of the valve, such as means for selectively adjusting the ''''blowdown'''' of the valve and means providing a predetermined flux gap as well as improved sealing and antisticking qualities in a valve having permanent magnet biasing means.

Description

United States Patent Evald Dunkelis [56] References Cited UNITED STATES PATENTS 3,189,675 6/1965 Moore et al. 25 l/65X 3,307,575 3/1967 Dickinson et al.. 137/491 3,454,039 7/1969 Dunkelis 137/491 3,454,040 7/1969 Dunkelis 137/491 Primary ExaminerM. Cary Nelson Assistant Examiner-Robert J. Miller Att0rneyNorman A. Witt ABSTRACT: A pressure responsive valve having a single tank opening and single main pallet which provides pilot operation to relieve both overpressure and vacuum conditions within the tank. Also disclosed are features provided to improve operation of certain portions of the valve, such as means for selectively adjusting the blowdown of the valve and means providing a predetermined flux gap as well as improved sealing and antisticking qualities in a valve having permanent magnet biasing means.

PATENTED MAR 212m SHEET 2 OF 2 MAGNETICALLY BIASEI) VALVE DEVICE This application is a continuation-in-part of application Ser. No. 625,758, filed Mar. 24, 1967 now 11.8. Pat. No. 3,454,040, by the present applicant for Pressure Responsive Valve Device.

This invention relates to a pilot operated relief valve providing pilot operation for either pressure or vacuum relief through a single tank opening covered by a single pallet, as disclosed in said earlier application. Furthermore, the invention relates to improvements in the construction and arrangement of magnetic pallets utilized in such valves.

It is a principal object of the present invention to provide a pilot operated relief valve having a single main pallet covering an opening communicating with the interior of the enclosure with which the valve is assr'ciated and operable in response to a predetermined pressure differential, either higher or lower, between .the interior of the enclosure and the surrounding atmosphere.

A further object is to provide a relief valve having two pilot portions, one operable in response to overpressure and the other in response to vacuum, the operation of either pilot serving to allow movement of a single main .pallet to the open position to relieve such overpressure or vacuum condition.

Another object is to provide a magnetically biased valve pallet having improved operating characteristics such as: accurate repeatability of operation in response to the same pressure'differential, greater reliability due to elimination of metal to metal contact and control of magnetic flux gap, and more accurate and simplified control of blowdown, i.e., the amount of decrease in pressure differential from opening to closing of the valve. I 4

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is asomewhat diagrammatic, elevational view, partly in section, of one embodiment of the invention showing certain movable elements in a first position;

I FIGS. 2 and 3 are elevational views as in FIG. 1 showing the elements in different positions; and

FIG. 4 is an exploded perspective view showing a portion of the device in greater detail.

The invention may be incorporated in various valve configurations for mounting on a tank, or like enclosure, to relieve a pressure differential between the interior and exterior of such enclosure. For example, the invention may be incorporated in valve devices such as those disclosed in copending application Ser. No. 600,1 l4, filed Dec. 8, 1966 now US Pat. No. 3,454,039 by the present inventor.. Such structures provide a flexible bellows, connected to the main pallet and movable therewith, in the place of the usual rigid valve body or diaphragm. The present invention is shown as being incorporated in such a device since the embodiment of the invention disclosed in aforementioned application Ser. No. 625,758 is so shown, but it will be understood that the particular construction of the valve body, as well as certain other conventional portions of the device, are subject to wide variation within the scope of the invention.

Turning now to the drawings, in FIG. 1 is shown a sectional view of an embodiment of the invention wherein pilot operation is provided for both pressure and vacuum operation of a single main pallet. Main pallet is vertically movable between open and closed positions with respect to valve seat 12 which defines an opening communicating with the interior of a tank structure, or other such enclosure, which is to be protected against damage due to excess pressure differentials by the valve device. Flexible bellows 14 is affixed in sealing arrangement with the surface of pallet 10 on the opposite side from seat 12 and is sealed at its opposite end to stationary end wall 16, thereby forming an enclosed chamber 15. Main pallet 10 and end wall 16 include check valves 18 and 20, respectively, which are shown diagrammatically since they may comprise any of a number of well-known designs suited for such purposeJCheck valve 18 is arranged to be moved to the open position by a pressure within the tank which exceeds the pressure within chamber 15. When there is essentially no pressure differential, or when the pressure within chamber 15 exceeds that within the tank, check valve 18 will be held in the closed position. Check valve 20 is moved to the open position by atmospheric pressure when the latter exceeds the pressure within chamber 15, and closed by pressurewithin the chamber when such pressure exceeds atmospheric.

Hollow tube 22 extends through an opening in end wall 16 and has threaded or otherwise affixed on the outer end thereof, tubular permanent magnet element 24. The open upper end of. the magnet element forms a valve seat which is engaged by a pallet in the form of ball 26 of magnetically permeable material. Thus, ball 26 is held in the closed position with respect to the seat formed on the end of magnet 24 by the attracting force exerted by the magnet on the ball, and by the weight of the ball. When the pressure within chamber 15 ex ceeds the forces tending to maintain ball 26 in engagement with its associated valve seat, the ball will be lifted off the seat, thereby opening the valve. Ball 26 is enclosed by cover 28 which may conveniently be threaded on the outside of magnet element 24. Sleeve 30 is inserted over cover 28 and clamped in a desired position with respect thereto so as to place openings in the cover and sleeve in a desired degree of registration, as will be explained more fully hereinafter. The portions of the sleeve and cover openings which are in registration cooperate to form opening 32 through which the opening defined by the valve seat on magnet 24 communicates with the atmosphere.

Hollow tube 34 extends through a central portion of main pallet 10. Permanent magnet element 36 is threaded on the lower end of tube 34 and has an outer end defining a valve seat covered by pallet 38 of magnetically permeable material. Cover 40 is inserted over magnet element 36 and pallet 38, and cooperates with sleeve 42 to provide opening 44 as described in connection with the upper pilot valve. Pallet 38 will be moved away from the seat on magnet element 36 by a pressure within chamber 15 which exceeds the pressure within the tank by an amount suffieient to overcome the attracting force exerted by magnet 36 on pallet 38 and the biasing force of return spring 46. The latter serves to move pallet 38 back into engagement with the seat after the pressure differential between chamber 15 and the tank has decreased sufficiently that the spring force is greater than such pressure differential plus the weight of pallet 38.

Operation of the present embodiment of the invention under conditions of excess pressure within the tank will now be described, with reference to FIG. 2. As the pressure within the tank increases check valve 18 will be opened and check valve 20 closed, whereby the pressure within chamber 15 will remain substantially equal to the tank pressure. Thus, the pressure on opposite sides of pallet 38, as well as main pallet 10, will be substantially the same while the pressure on the lower side of ball 26 will exceed the atmospheric pressure on the upper side thereof. When this pressure differential is sufficient to overcome the attracting force of magnet 24 on ball 26, plus the weight of the ball, the latter will be lifted off the seat and allow gas to escape from chamber 15 through tube 22 and opening 32 to the atmosphere. The size of opening 32 and the opening through tube 22 are so designed that gas can escape from chamber 15 at a faster rate than additional pressurized gas from the tank can enter chamber 15 through check valve 18. Thus, the pressure within chamber 15 will drop rapidly after ball 26 has lifted off the seat on magnet 24 thereby creating a pressure differential between chamber 15 i and the tank. This pressure differential will allow main pallet to be lifted by pressure from below to vent the tank to the atmosphere. The elements are shown in FIG. 2 as they would appear after the pressure within chamber has exceeded the atmospheric pressure by an amount sufficient to lift ball 26, and for the pressure within chamber 15 then to decrease sufficiently to allow tank pressure to lift pallet 10, but before the blowdown pressure has been reached (i.e., before the pressure in chamber 15 and the volume of gas flow tending to maintain ball 26 in the open position have decreased sufficiently that the weight of the ball will cause it to drop back into engagement with the seat on magnet 24). Main pallet 10 will return to the closed position on seat 12 when the tank pressure has decreased sufficiently that the weight of the pallet and elements carried thereby exceed this pressure. Bellows 14 may also provide a spring rate tending to move pallet 10 to the closed position.

When the pressure within the tank falls below atmospheric pressure check valve 18 will be closed and check valve 20 may be opened if the pressure within chamber 15 is initially below atmospheric; at any rate, the pressure within chamber 15 will be at or above atmospheric pressure when the tank pressure is below atmospheric. When the differential between the pressure within chamber 15 and the lower pressure within the tank is great enough pallet 38 will be forced away from the seat on magnet 36. This takes place when the pressure in chamber 15 exceeds tank pressure sufficiently to overcome the attracting force of magnet 36 on pallet 38 plus the biasing force of spring 46, less the weight of pallet 38 which also tends to move it to the open position. The air or gas within chamber 15 may then enter the tank through tube 34 and opening 44 at a rate faster than additional air can enter through check valve 20, thereby causing the pressure within chamber 15 to drop below atmospheric. The elements are so dimensioned that the area on the upper surface of pallet 10 enclosed by bellows 14 is greater than the area of the lower surface of pallet 10 which lies inside valve seat 12. Thus, the lower surface of pallet 10 which lies outside seat 12 is acted upon by atmospheric pressure while a greater area of the upper surface is subjected to a pressure below atmospheric. Therefore, the atmospheric pressure acting upwardly on main pallet 10 outside of valve seat 12 will cause the main pallet to lift and vent the tank to the atmosphere.

The elements are shown in FIG. 3 in their positions when the vacuum relief set pressure has been reached. Pallet 38 has been moved to the open position, allowing gas to flow from chamber 15 into the tank, thereby allowing the atmospheric pressure acting upwardly on main pallet 10 outside valve seat 12 to lift the main pallet and allow the tank to be exposed directly to the atmosphere. Spring 46 will move pallet 38 back into engagement with the seat on magnet 36 after the pressure differential and volume of gas flow (as determined by the size of opening 44) between chamber 15 and the tank have decreased sufficiently that the spring can overcome the combined pressure differential and the weight of pallet 38.

Although two different types of pallets are shown in the pilot portions of the valve, in the form of ball 26 and cylindrical slug 38, obviously a variety of different configurations could be used, and the configuration of one pilot pallet is not dependent upon the other. The use of a ball-type pallet may have some advantage over the use of a pallet having a fiat surface in contact with the valve seat on the end of the magnet. The ball is self-aligning due to its configuration, with respect to the seat and any rotation or other relative motion which the ball may undergo when it is in the open position will have no effect on operation of the device. Although cover 40 will provide a measure of alignment for pallet 38 sufficient to prevent malfunction, the pallet is still subject to some lateral displacement as well as rotation when it is in the open position. This may result in some misalignment with the pole pieces of the magnetic element, thereby resulting in some change in the attracting force exerted by the magnet on the pallet after the latter has been moved from its initial relative position to the magnet.

FIG. 4 provides a clearer showing of certain details of the pilot portion of the device and may be applied, of course, to either the pressure or the vacuum pilot. By way of example, reference numerals used in FIG. 4 are the same as those used for the vacuum pilot portion of the valve shown in FIGS. 1 through 3. A further desirable feature is the provision of layer 50 of nonmagnetically permeable material (e.g., Teflon) secured to the surface of pallet 38 which contacts the seat on magnetic element 36 by a suitable adhesive, mechanical clamping or other convenient means. Layer 50 may be provided in any desired thickness to provide a predetermined flux gap between pallet 38 and magnetic element 36, thereby having a predetermined effect on the attracting force exerted by the magnet on the pallet. Also, by preventing metal to metal contact at the valve seat improved sealing is achieved, as well as lessening the tendency of the pallet to freeze or otherwise stick to the seat.

Openings 52 and S4 in cover 40 and sleeve 42, respectively, are shown in FIG. 4 and cooperate when the elements are assembled to form opening 44 shown in FIGS. 1 through 3. Sleeve 42 is shown here in a form resembling a hose clamp, or the like, and may be inserted over cover 40 and retained in a desired position thereon by tightening bolt 56. The size of opening 44 through which gas escapes from the pilot valve may be selectively adjusted by rotating sleeve 42 relative to cover 40, thereby changing the degree of registration of

openings

52 and 54. Changing the size of opening 44 changes the relative size of the openings through which gas may enter and leave chamber 15 when pallet 38 is in the open position. This, in turn, controls the so-called blowdown" of the valve. That is, pallet 38 is biased in the closed position and requires a predetermined pressure differential on opposite sides thereof in order to be moved to the open position. Once the pallet has been so moved it is maintained in the open position by the volume rate of gas flow, as determined by the pressure differential and size of the opening through which the gas flows. Secondary biasing means, such as the weight of the pallet, a return spring, or other such means, are provided to move the pallet back to the closed position when the pressure differential has decreased to a point where the force produced by the volume rate of gas flow will be overcome by the secondary biasing means. The rate of change of the pressure within chamber 15 and hence the volume rate of gas flow tending to maintain the pallet in the open position, are functions of the rate at which gas may escape from the chamber relative to the rate at which additional gas may enter. Since the sizes of the openings in the check valves are fixed, this relationship is determined by the adjustment of sleeve 42 on cover 40 which controls the size of opening 44.

From the foregoing description it is apparent that the present invention provides a pressure responsive relieve valve having a single main pallet movable between open and closed positions with respect to an opening communicating with the interior of a tank, or other such enclosure with which the valve is associated, with pilot operation to relieve both overpressure and vacuum conditions within the tank. The invention further provides additional unique features associated with the pilot valve itself designed to improve operation thereof. Such features are particularly suited for incorporation in valves having pallets magnetically biased in the closed position.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are in tended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

in 1 nm rmsn I claim:

1. A pressure responsive valve device having a single main pallet movable between open and closed positions with respect to a valve seat to vent a tank structure, or the like, in response to either excess pressure or excess vacuum therein, said valve device comprising:

a. a first pilot valve including a seat defining an opening and a pallet movable relative the opening between open and closed positions and biased toward the closed position;

. a second pilot valve including a seat defining an opening and a pallet movable relative the seat between open and closed positions and biased toward the closed position;

c. means for moving said first pilot valve to its open position in response to a predetermined increase of the pressure within said tank above atmospheric;

. means for moving said second pilot valve to its open position in response to a predetermined decrease of the pressure within said tank below atmospheric;

e. means for moving said main pallet to its open position in response to movement'of either of said first and second pilot valves to their open position;

f. a pair of pressure responsive check valves allowing fluid flow in one direction only, one of said check valves allowing flow from the atmosphere into said chamber and the other allowing flow from the interior of said tank into said chamber, the fluid flow allowed by either check valve being substantially less than that allowed by an open pilot valve; and

g. means defining an enclosed chamber having one internal wall defined by a surface of said main pallet, the opposite surface of said main pallet being exposed over a first portion to the interior of said tank and over a second portion to atmospheric pressure.

2. The invention according to claim 1, wherein the pallets of said first and second pilot valves are biased in their closed position by permanent magnet means.

3. The invention according to claim 2, and means for additionally biasing said pilot valve pallets to closed position.

4. The invention according to claim 3, wherein the additional biasing means for the pallet of one of said first and second pilot valves is defined by the gravitational force of the pallet.

5. The invention according to claim 3, wherein the additional biasing means for the pallet of one of said first and second pilot valves is defined by spring means.

6. The invention according to claim 1, wherein one of the seat and pallet of each pilot valve comprises a permanent magnet means and the other a magnetically permeable material.

7. The invention according to claim 1, and a layer of nonmagnetic material affixed to the surface of the pallet of one of said pilot valves which covers its seat, so as to be interposed directly between and provide a predetermined flux gap for said magnet means and magnetically permeable material when the pallet is in seated position.

8. The invention according to claim 7, wherein the pallet of at least one of said pilot valves is arranged within a housing having aperture means therein, so that gas flowing by said pilot pallet passes through both the opening of the seat and the aperture means.

9. The invention according to claim 8, and means for changing the effective area of the aperture means to regulate the volume rate of gas flow past the pilot pallet.

10. The invention according to claim 9, wherein said aperture means effective area changing means includes a first fixed opening in said housing and a sleeve member movably secured on the housing having a second fixed opening therein for variable registry with said first fixed opening to define the effective area of the aperture means.

Claims

1. A pressure responsive valve device having a single main pallet movable between open and closed positions with respect to a valve seat to vent a tank structure, or the like, in response to either excess pressure or excess vacuum therein, said valve device comprising: a. a first pilot valve including a seat defining an opening and a pallet movable relative the opening between open and closed positions and biased toward the closed position; b. a second pilot valve including a seat defining an opening and a pallet movable relative the seat between open and closed positions and biased toward the closed position; c. means for moving said first pilot valve to its open position in response to a predetermined increase of the pressure within said tank above atmospheric; d. means for moving said second pilot valve to its open position in response to a predetermined decrease of the pressure within said tank below atmospheric; e. means for moving said main pallet to its open position in response to movement of either of said first and second pilot valves to their open position; f. a pair of pressure responsive check valves allowing fluid flow in one direction only, one of said check valves allowing flow from the atmosphere into said chamber and the other allowing flow from the interior of said tank into said chamber, the fluid flow allowed by either check valve being substantially less than that allowed by an open pilot valve; and g. means defining an enclosed chamber having one internal wall defined by a surface of said main pallet, the opposite surface of said main pallet being exposed over a first portion to the interior of said tank and over a second portion to atmospheric pressure.