Abstract:
A pressure activated valve incorporates arrangements of permanent magnets within the valve housing to establish a pressure threshold at which the valve is either opened or closed. The magnets are mounted relative to one another with opposing polarities; so that the repelling force between the magnets establishes the pressure threshold at which the valve is operated.

Description:
BACKGROUND 
   Pressure activated valves are employed in various systems to operate when pressure applied to the valve exceeds some pre-established threshold. Typically, such valves employ coil springs or magnetic attraction between either two magnets or a magnet and magnetizable material to establish the threshold pressure. Once the threshold has been reached, the valve is operated by overcoming the spring force or the magnetic attraction force. It is desirable to provide an improved pressure activated valve. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic cross-sectional view of an embodiment of the invention in one state of operation; 
       FIG. 2  is a cross-sectional diagrammatic view of the embodiment shown in  FIG. 1  in a second state of operation; 
       FIG. 3  is a cross-sectional view taken along the lines  3 - 3  of  FIG. 1 ; 
       FIG. 4  is a diagrammatic cross section of another embodiment of the invention; 
       FIG. 5  is a cross section taken along the line  5 - 5  of  FIG. 4 ; 
       FIG. 6  is a cross section taken along the line  6 - 6  of  FIG. 4 ; 
       FIG. 7  is a diagrammatic cross section of another embodiment of the invention; 
       FIG. 8  is a cross section taken along the line  8 - 8  of  FIG. 7 ; 
       FIG. 9  is a diagrammatic cross section of another embodiment of the invention; and 
       FIG. 10  is a diagrammatic cross section of the embodiment shown in  FIG. 9  in a different mode of operation from that shown in  FIG. 9 . 
   

   DETAILED DESCRIPTION 
   Reference now should be made to the drawings, in which the same reference numbers are used throughout the different figures to designate the same or similar components.  FIG. 1  is a diagrammatic cross-sectional view of an embodiment of the invention configured as a pressure relief valve, which is operated when the pressure at an inlet exceeds a pre-established threshold amount or force. 
   The valve of  FIG. 1  includes an outer cylindrical body  10  made of non-magnetic material and having an inlet  12  and an outlet  14  in it. As shown in  FIG. 1 , the inlet  12  is coaxial with the main body portion  10  of the valve, while the outlet  14  is located in the outer periphery of the housing  10 . The relative locations of the inlet  12  and the outlet  14 , however, are not important, since various configurations of the valve can be effected using the same operating principles which are illustrated. 
   In the valve of  FIG. 1 , the threshold pressure is established by two opposing circular permanent magnets  16  and  18 . These magnets may be made of any suitable material which provides the necessary magnetic force, as well as resistance to any corrosive materials which may be used in the system with which the magnets are used. The permanent magnets may be made of ferrous material, ceramics, or various types of rare earth magnetic material. The particular type of material is selected for the application in which the valve is to be used. The operating principles are the same, irrespective of the type of magnetic material which is employed. 
   As shown in  FIG. 1 , the magnets  16  and  18  are magnetized axially, that is through their thickness, to present positive and negative poles on the opposing surface areas of the respective magnets. The magnets are mounted in the housing  10 , with the facing magnetic surfaces being of the same polarities (either positive or negative magnetic polarity); so that they are in a repelling or repulsive orientation, tending to push the magnets  16  and  18  apart. 
   The magnet  18  is mounted on a threaded shaft  22 , which is threaded through an opening in the bottom of the valve housing  10 . The vertical orientation or position of the magnet  18  within the valve housing  10  is established by rotating the shaft  22  through a head  24 , in either direction, to move the magnet  18  up and down vertically within the housing  10 . 
   The second magnet  16  carries a conical rubber or resilient valve closing member  20  on its upper surface (as shown in  FIGS. 1 and 2 ) and is guided for reciprocal movement axially within the housing  10  by means of internally spaced longitudinal ribs  30  configured to ride within notches  32  on the periphery of the magnet  16 . Alternatively, a smaller diameter magnet  16  without the notches  32 , configured to ride within the circle defined by the innermost extending tips of the ribs  30 , could be employed. On the other hand, the magnet  16  could employ projections spaced about its periphery to allow it to slide axially within the housing  10 . Any configuration which allows the passage of fluid around the periphery of the magnet  16  (and also around the periphery of the magnet  18 ) may be employed. 
   The force with which the valve is held closed by the repulsive forces between the fixed position magnet  18  (the position of which can be adjusted as described previously) and the movable magnet  16  is established by a number of different parameters, namely the surface area of the magnets  16  and  18 , the magnetic strength of the magnets  16  and  18  causing the repulsive force between them, the distance which is established by the rotation of the screw  22 , and the temperature in which the valve is operated. 
   The valve illustrated in FIGS.  1 , 2  and  3  is operated as a pressure relief valve of the type which is used, for example, on water heaters for relieving internal pressure of the water when it exceeds a pre-established threshold. The valve of FIGS.  1 , 2  and  3  also may be used in various types of hydraulic systems and the like. Once the pressure P at the inlet  12  of the valve exceeds the threshold established by means of adjustment of the various parameters described above, the repulsive force between the two magnets  16  and  18  is overcome; and the movable magnet  16  is moved downwardly, as shown in  FIG. 2 , to allow relief of fluid in excess of the threshold pressure P to flow through the inlet  12 , around the magnets  16  and  18 , and out through the pressure relief outlet  14 , as shown in  FIG. 2 . 
   FIGS.  4 , 5  and  6  are directed to a cylindrical valve configuration which operates to close the valve when the inlet pressure applied to the left-hand side as shown in  FIG. 1  is less than a first threshold pressure P 1 , and to open the valve when the fluid pressure applied to the inlet side on the left hand, as shown in  FIG. 1 , is greater than the threshold pressure P 1  and less than a second higher threshold pressure P 2 . The valve of  FIG. 4  once again is closed when the fluid inlet pressure exceeds the second higher pressure P 2 . In summary, the valve of  FIG. 4  is closed when the pressure is less than the first lower threshold P 1 , is open when the pressure is between P 1  and a greater pressure P 2 , and the valve is again closed when the inlet fluid pressure exceeds the second greater threshold pressure P 2 . 
   In FIGS.  4 , 5  and  6 , a fixed position permanent magnet in the form of a circular disc  48  is mounted in the right-hand side of the valve housing  40 . The mounting may be effected in a number of different ways; and as illustrated in  FIG. 5 , four spaced supporting arms  50  mount the magnet  48  centrally and coaxially in the housing  40 . This allows fluid flow to take place around the periphery of the magnet  48  between the supporting arms  50 . Alternatively, the magnet  48  could be provided with a number of apertures or holes  58  through it to allow the passage of fluid through the magnet; and the outer periphery of the magnet  48  could be secured in any suitable manner to the internal diameter of the housing  40 . 
   Two spaced valve seats  42  and  44  are located toward the left of the magnet  48  as viewed in  FIG. 4 . These valve seats generally are in the form of a washer-like configuration, with the external diameter attached to or affixed to the interior of the housing  40  in any suitable manner. The facing surfaces of the valve seat  42  and  44  preferably are formed of a resilient material of any suitable type to withstand the pressure and type of fluid which is flowing through the housing  40 . 
   A movable permanent magnet  46  is arranged for reciprocal movement between the facing surfaces of the valve seats  42  and  44 , as determined by the repulsive magnetic forces between the two magnets  46  and  48  and the pressure of the fluid entering the housing  40  from the left-hand side, as viewed in  FIG. 4 . The manner in which the permanent magnet  46  is mounted for the reciprocal movement may be as described above in conjunction with  FIG. 3 . The outer periphery of the magnet  46  is arranged to allow for fluid flow around that outer periphery and through the housing  40  whenever the magnet  46  is in an intermediate position between the valve seats  42  and  44 , as shown in  FIG. 4 . 
   When the valve of  FIG. 4  is in its rest or relaxed condition without any fluid being applied to the left-hand side, the repulsive force between the two magnets  46  and  48  is such that the magnet  46  is pushed by a force P 1  against the right-hand side of the valve seat  42  to close the valve. When fluid pressure in excess of an initial lower pressure P 1  is applied to the inlet on the left-hand side of the valve of  FIG. 4 , the repulsive force P 1  is overcome and the magnet  46  is moved from the position just described to the intermediate position shown in  FIG. 4 . As long as the fluid inlet pressure of the fluid applied to the left-hand side of the valve is between this lower threshold P 1  and a higher threshold P 2 , fluid flows through the valve from the left-hand end to the right-hand end, around the peripheries of the magnets  46  and  48 , and through the centers of the valve seats  42  and  44 . 
   When, however, the fluid pressure applied through the inlet side of the valve exceeds a second threshold pressure P 2 , the movable magnet  46  moves toward the right to engage the facing surface of the valve seat  44  and once again close the valve. A reversal of these pressures results in a reversal of the operation described above; so that this valve only allows a fluid flow at a pressure between the pressures P 1  and P 2  to take place through it. 
   The valve which is illustrated in  FIGS. 7 and 8  is designed as a bi-directional valve which normally allows fluid flow through it in either direction, and which is closed in response to a pressure in excess of a pre-established threshold in either direction. In the valve of  FIG. 7 , a valve seat in the form of a washer-shaped member  42  is located in the center of the housing  40 . The valve seat  42  is coated with or is made of a resilient material on each of its surfaces; so that whenever a permanent magnet  66  or  68  engages one side or the other of the valve seat  42 , the valve is closed. 
   As shown in  FIG. 8 , the circular permanent magnets  66  and  68  are provided with a diameter which is less than the interior diameter of the housing  40 , and the magnets are held in their relaxed or unoperated positions against spaced teeth  70  located about the periphery on the interior of the housing  40 , as shown most clearly in  FIG. 8 . This allows fluid to flow around the edges of the magnets  66  and  68 , and through the holes in the center of the valve seat  42  in either direction through the valve. The repulsive forces of the magnets  66  and  68  cause them to attain the position shown in  FIG. 7 . 
   Whenever a pressure in excess of an established threshold, for example P 1 , is encountered by the fluid flowing from left to right through the left-hand end of the valve, the threshold repulsive force or pressure established by the magnetic force between the magnets  66  and  68  is overcome; and the magnet  66  is moved toward the right to seat on the valve seat  42 , blocking further fluid flow from left to right through the valve. Similarly, whenever pressure in excess of P 1  established by the magnets  66  and  68  is applied from the right-hand side of the valve to flow from right to left through the valve, the magnet  68  moves toward the left to engage the opposite side of the valve seat  42 , and close the valve. Thus, the valve of  FIGS. 7 and 8  allows fluid flow in a bi-directional direction so long as that fluid flow is less than a predetermined threshold pressure in either direction. 
     FIGS. 9 and 10  are directed to a magnetic repulsive valve which is closed when pressure in excess of a predetermined amount (established by the repulsive forces between the fixed magnet  48  and the movable magnet  46 ) is exceeded. The configurations of the magnets are similar to the ones described above in conjunction with the fixed magnet  48  of  FIG. 4  and the movable magnets  66  and  68  of  FIGS. 7 and 8 , for example. Once a threshold pressure P 1  is exceeded by fluid applied to the left-hand side of the system shown in  FIGS. 9 and 10 , the movable magnet  46  is pushed toward the right, as shown in  FIG. 10 , to close the valve seat  44  in a manner similar to that described above in conjunction with the operation of  FIGS. 4 and 7 . No further fluid flow from left to right through the valve member  40  then can take place as long as the pressure of the fluid on the left-hand side of the valve exceeds the pre-established threshold pressure. 
   The various types of valve configurations which have been described above may be incorporated into a variety of different operating systems for handling fluids in the form of both gases and liquids. Systems employing the repulsive magnetic forces of the valves described above in conjunction with the different embodiments operate effectively as check valves, pressure relief valves and pressure regulators, and can be substituted for cumbersome valve arrangements for performing these functions which have been used in the past. 
   The foregoing description of various embodiments of the invention is to be considered as illustrative and not as limiting. Various changes and modifications will occur to those skilled in the art for performing substantially the same function, in substantially the same way, to achieve substantially the same result, without departing from the true scope of the invention as defined in the appended claims.