US2734522A - waltman - Google Patents

Description

Feb. 14, 1956 R. M. WALTMAN VALVE Filed June 24, 1952 I'---INLET m/. wm V m @M w@ M. @ww r.

ATT( )KNEY United States Patent VALVE Robert M. Waltman, Towson, Md., assignor to Bendix Aviation Corporation, Baltimore, Md., a corporation of Delaware Application June 24, 1952, Serial No. 295,233

Claims. (Cl. IS7- 197) The subject invention relates generally to valves and more particularly to a check valve for a gas-liquid pressure system wherein it is desirable to restrict motion of a body of liquid therein.

In certain gasliquid pressure systems, a body of liquid can move between dened points of the system under the inliuence of a differential pressure thereacross. Often it is necessary to utilize positive means to prevent movement of the liquid beyond the defined points and such means may be normally embodied in some form of check valve. An example of such a system is a mercury manometer system having pumps connected to opposite sides of the mercury for maintaining a differential pressure thereacross. Proper control of the pumps permits control of the height of the mercu1y column-however, under abnormal conditions of operation, the mercury may have a tendency to surge into the pump mechanisms, thereby rendering the fluid system inoperative and possibly damaging the pump mechanisms.

Such a system may embody the usual glass tube extending upwardly from a mercury reservoir. A pump is connected to the open end of the glass tube and may operate continuously to establish a substantially complete vacuum pressure over the surface of the mercury. By connecting another pump to a suitable outlet in the mercury reservoir, and by varying its etect to create a pressure on this side of the mercury varying from atmospheric pressure to a substantially complete vacuum pressure, the column of mercury can be made to rise and fall within the glass tube. In such a system, the constant pressure pump is normally termed a head pump whereas the vari able pressure pump may be termed a vacuum pump.

Such systems may also be used under pressurizing conditions when it is desirable to raise the mercury column above atmospheric pressure levels. ln such case, the vacuum pump may be by-passed and air, at pressures exceeding atmospheric pressure, is introduced into the mercury reservoir.

With the above in mind, let us assume a surge of air pressure when operating under pressurizing conditions. This will cause the mercury to surge from its normal zone into the head pump. Once this happens, the system becomes inoperative, requiring dismantling of the pump for clean-up purposes, resulting in lost time in production, extraordinary plant maintenance, and, in some instances, permanent damage to the pump.

The same deleterious efrects could result upon failure of the head pump when the vacuum pump is in the low vacuum pressure range. ln this case, the mercury would tend to surge into the vacuum pump.

To prevent the deleterious surging of mercury into the pumps, the valve of the subject invention has been devised and in the form shown herein comprises a check valve of the ball type having the valve head normally held away from the seat by means of a strong permanent magnet. Suitable clearance is provided around the ball and the magnet to permit free communication of air through the valve. integrally connected to the head is a piston whose working face normally looks at the section of the system from which surges of mercury can be expected. The piston is positioned in the valve body between the inlet and outlet ports and is adapted to be rapidly moved upon contact of the mercury against its Working face. The forces developed by the surging mercury against the Working face of the piston are suflicient to move the pis ton against the normally restraining force of the permanent magnet and thereby move the connected valve head onto its valve seat which, of course, electively checks the liow of mercury. The piston is suitably ported to permit free communication of air between the inlet and outlet ports under normal operating conditions. However, the ports are in the nature of capillary openings so that whenever the mercury contacts the piston, the valve will be closed before any mercury can work its way through the capillary openings. For the particular application shown, stainless steel, glass and mercury resistant plastics were selected Yfor the materials used so that none of its parts would be affected by the presence of mercury in the system.

The advantages and benefits to be derived from the subject valve Will be best understood upon reference to the detailed description set forth below when taken in conjunction with the drawings annexed hereto in which:

.Figure I is a schematic view of a simple mercury manometer system embodying the novel valve and;

Figure Il is a sectional view of the valve itself.

Referring first to Figure l, there is shown a mercury manometer in the form of a vertical glass tube 3 having its lower extremities in communication with the mercury reservoir 4. The upper end of the tube 3 is connected by suitable conduits to a pump 5 and the reservoir 4 is also suitably connected to a pump 6. interposed between the pumps and the manometer is the valve of the subject invention generally indicated by the numeral 7 and shown in detail in Figure II. The precise details of construction of the tube 3, the reservoir 4, the pumps 5 and 6 and the connections therebetween, manner of supporting same, et cetera, form no part of the subject invention and for the sake of brevity have not been included in the specification. Conventional components familiar to those in the art can be used in the system.

Now referring to Figure Il, there is shown the details ofl the valve 7. lt comprises a valve body 8 formed of a suitable mercury resistant material which in the form shown comprises a glass tube. Threadably engaging the open extremities of tube 8 are the projecting tubes 9 and lo.` These tubes may also be formed of glass or a similar mercury resistant material and are provided for the purpose of making the necessary external connections to the system in which the valve is to be used. The inner extremity of projection 9 has formed therein the valve seat l1. The projections 9 and 10 are conveniently referred to hereafter as the outlet and inlet openings or ports.

Cooperating with the valve seat 11 is the stainless steel ball 12 normally held against the permanent magnet 13 but shown in the drawing in its intermediate position between the magnet 13 and the valve seat 11. integrally connected to the ball 12 is the connecting rod i4, to which is affixed the piston 15, which slidably engages the bore 16 provided in the valve body. The magnet 13 is suitably apertured to permit unrestrained motion of the connecting rod 14 therethrough. Further, the magnet is suitably formed to permit free communication of air between the inlet and outlet ports when the ball 12 rests against it.

The piston 15 is suitably ported as at 17 to permit free access of air between the inlet and outlet ports and it is to be noted that the ports or vents 17 are in the nature of capillary openings,

The bali 12, the magnet 13, the connecting rod 14, and the piston 15 are formed of suitably mercury resistant materials which in the case of the ball and the connecting rod is stainless steel and in the case of the piston is glass or mercury resistant plastic. The magnet is of a suitable high permeability, high strength, nickel iron, mercury resistant material commercially available.

With the above arrangement of parts in mind and with the valve connected in the system shown in Figure l, its operation will be clearly seen. In the system the pump 5 is designated as a head pump and pulls a constant, continuous vacuum over the column of mercury i9. The pump 6 is designated as a vacuum pump and causes a varying pressure to exist in the reservoir 4, the pressure ranging from atmosphere to a vacuum. By vacuum pressure is meant that degree of vacuum which can be obtained with the best commercially available equipment. With full atmospheric pressure being developed by pump 6, the mercury column 19 will rise to its upper limit in the tube 3.

The column of mercury will fall as the vacuum pump develops lower and lower vacuum pressures, but if for any reason the head pump 5 fails during this operation, thc mercury will immediately surge toward the pump 6. When this happens, it will rush into the valve 7 through its inlet port 19 and contact the working face of the piston 15. The valve is so designed that this contact will develop a force sufficient to overcome the force of attraction exerted by the magnet 13 on the ball l2. This will cause the ball 12 to move away from the magnet i3 and, as the air gap separating the last named parts increases, the net forces acting on the ball 12 will rapidly increase, thereby causing the ball to move with a snap action onto the seat 1l. Thus the valve is tightly closed and mercury is prevented from flowing to the pump 6. A positive snap action is obtained during this sequence of events thereby rendering the valve highly effective for the purpose intended.

In a like manner the valve 7 can be used between the head pump 5 and the mercury column 19 to prevent any mercury from fiowing to the head pump. Such an eventuality would occur when operating the system under pressurizing conditions, that is, when the pump 6 is bypassed and air, at pressures above atmospheric pressure, is introduced into the reservoir 4. With the inlet port connected to the upper end of tube 3, and the outlet port 9 being connected to the pump 5, and upon a sudden surge of air pressure into the reservoir, the mercury will surge toward the head pump but will be checked by valve 7.

Thus, it is seen that a simple, effective, positive, snapacting valve is obtained by the above described arrangement of parts ideally suited for use in a mercury manometer system or any similar system.

What is claimed and desired to be secured by United States Letters Patent is:

l. A snap-acting valve assembly adapted to be interposed between a body of liquid and a pump for pressurizing the liquid, said assembly functioning to avoid loss of liquid from the body and/ or damage to the pump through contact with the liquid, comprising: a valve body provided with a valve chamber, said body having a first opening for communicating said chamber with said liquid and a second opening, spaced from said first opening, for communicating said pump with said chamber, a valve seat coacting with said second opening, a valve closure member coacting with said seat, a holding device positioned in 'said valve `body between said first opening and said valve closure member and functioning to normally releasably hold said member off its seat, a piston interposed between s'aid holding device and said first opening, means providing a driving connection between said piston and valve closure member, and orifice means of a nature such as to permit relatively free flow of air from said first opening to saidsecond opening across said piston but interposing resistance to the passage of liquid, said piston when subjected to the pressure of liquid passing through said first opening freeing said valve closure member from said holding device and driving it to its seat.

2. A snap-acting valve assembly adapted to be interposed between a body of liquid and a pump for pressurizing the liquid, said assembly functioning to avoid loss of liquid from said body and/ or damage to the pump through contact with the liquid, comprising: a valve body provided with a valve chamber, said body having a first opening for communicating said chamber with said liquid and a second opening, spaced from said first opening, for communicating said pump with said chamber, a valve seat coacting with said second opening, a valve closure member coacting with said seat, a holding device positioned in said valve body between said first opening and said closure member and functioning to normally releasably hold the latter off its seat, means providing for the free fiow of air past said device and also past said closure member when the latter is unseated, a piston interposed between said holding device and said first opening, said piston being provided with one or more restricted orifices of a nature such as to permit relatively free ow of air from said first opening to said second opening across Said piston but interposing resistance to the passage of liquid, means providing a driving connection between said piston and said closure member, said piston when subjected to the pressure of liquid passing through said rst opening freeing said valve closure meniber from said holding device and driving it to its seat.

3. A snap-acting valve assembly adapted to be interposed between a body of liquid and a pump for pressurizing the liquid, said assembly functioning to avoid loss of liquid from said body and/or damage to the pump through contact with the liquid, comprising: a valve body provided with a valve chamber, said body having a first opening for communicating said chamber with said liquid and a second opening, spaced from said first opening, for communicating said pump with said chamber, a valve seat coacting with said second opening, a paramagnetic valve closure member coacting with said seat, a holding magnet positioned in said valve body between said first opening and said closure member and functioning to normally hold the latter olf its seat, means providing for the free flow of air past said magnet and also past said closure member when the latter is unseated, a piston interposed between said magnet and said first opening and having a driving connection with said closure member, and orifice means of a nature such as to permit relatively free flow of air from said first opening to said second opening across said piston but interposing resistance to the passage of liquid, said piston when subjected to the pressure of liquid passing through said first opening freeing said valve closure member from said magnet and driving it to its seat.

4. A snap-acting valve assembly' adapted to be interposed between a body of liquid and a pump for pressurizing liquid, said assembly functionning to avoid loss of liquid from said body and/ or damage to the pump through contact with the liquid, comprising: a valve body provided with an elongated valve chamber, said body having a first opening for communicating said chamber with said Y liquid and a second opening, spaced from said first opening, for communicating said pump with said chamber, a valve seat coacting with said second opening, a paramagnetic valve closure member coacting with said scat, a holding magnet positioned in said valve body between said first opening and said closure member and functioning to normally hold the latter off its seat, a piston interposed between sai'd magnet and said first opening, a rod projecting through said magnet and connected at its opposite ends to said piston and saidclosure member, said piston being provided with one or more restricted orifices of Va nature su'ch 'as to permit relatively free ow of air from said first opening to said second opening across said piston but interposing resistance to the passage of liquid, means providing for the free flow of air past said magnet and also past said closure member when the latter is unseated, said piston when subjected to the pressure of liquid passing through said rst opening freeing said valve closure member from said magnet and driving it to its seat.

5. A snap-acting valve assembly adapted to be interposed between a body of liquid and a pump for pressurizing the liquid, said assembly functioning to avoid loss of liquid from said body and/ or damage to the pump through contact with the liquid, comprising: a valve body provided with an elongated valve chamber, said body having a rst opening at one end of said chamber for communieating the chamber with said liquid and a second opening at the opposite end of said chamber for communicating said pump with the chamber, a valve seat coacting with said second opening, a paramagnetic valve closure member coacting with said seat, a magnet positioned in said valve body between said first opening and said closure member and functioning to normally hold the latter off its seat, a piston interposed between said magnet and said first opening, a piston rod providing a driving connection between said piston and said valve closure member, said rod slideably projecting through said magnet, means providing for the free flow of air past said magnet and also past said closure member when the latter is unseated, said piston being provided with one or more restricted ow orifices of a capillary nature permitting flow of air from said rst opening to said second opening across said piston but interposing resistance to the iiow of liquid, said piston when subjected to the pressure of liquid passing through said irst opening freeing said valve closure member from said magnet and driving it to its seat.

References Cited in the ile of this patent UNITED STATES PATENTS

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