Abstract:
A high capacity coaxial gas valve assembly having a coaxial construction with three valves, in which the assembly opens a smaller second valve prior to opening a larger first valve so that the valve can be operated by a relatively smaller and less expensive coil. In addition, or instead, the valve members may be configured so that the first valve is opened with the impact of a moving element that allows the valve to be operated with a relatively smaller and less expensive coil.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to electromagnetically operated valves, and more particularly to a high capacity co-axial gas valve. 
   A solenoid valve having co-axial armatures in a single coil design is disclosed in Konsky et al., U.S. Pat. No. 6,047,718, incorporated herein by reference. This valve is provides redundant gas control with only a single solenoid, with a simple and reliable construction. However, for larger valve sizes, e.g., ⅝ inch and larger, larger and more expensive solenoids are generally required to overcome the gas pressure and open the valve. 
   SUMMARY OF THE INVENTION 
   The present invention provides a valve of simple an inexpensive construction with a larger size and therefore larger capacity, but which can be operated with a relatively small and inexpensive solenoid. 
   Generally, a first embodiment of a valve assembly constructed according to the principles of this invention comprises: an electrically energizable solenoid coil having a coil axis. An outer armature is mounted relative to the coil for axially movement proximally toward and distally away from the coil, parallel to the coil axis. An inner armature inside the outer armature, and is likewise axially movable proximally toward and distally away from the coil, parallel to the coil axis. At least the inner armature is drawn proximally when the solenoid coil is energized. The assembly comprises a first valve, having a first valve seat and a first valve member. The first valve member is movable between a closed position in which the first valve member abuts the first valve seat, and an open position in which the first valve member is spaced from the first valve seat. A first spring member resiliently biases the first valve member to its open position. 
   The assembly further comprises a second valve, having a second valve seat on the first valve member, and a second valve member on the outer armature. The second valve member is movable with the outer armature between a closed position in which the second valve member abuts the second valve seat, and an open position in which the second valve member is spaced from the second valve seat. A second spring member engages the outer armature and resiliently biases the second valve member carried thereon to its closed position. 
   The assembly further comprises a third valve, having a third valve seat and a third valve member on the inner armature. The third valve member is movable with the inner armature between a closed position in which the third valve member abuts the third valve seat, and an open position in which the third valve member is spaced from the third valve seat. A third spring member engages the inner armature and resiliently biases the third valve member carried thereon to its closed position. 
   Energizing the solenoid coil causes the inner armature to move proximally against the bias of the third spring member, moving the third valve member to its open position, the movement of the inner armature causing the outer armature to move proximally against the bias of the second spring member, moving the second valve member to its open position, and allowing the first valve member to move under bias of the first spring member to its open position. The opening of the smaller second valve reduces some of the gas pressure making it easier to open the larger first valve. In addition in some embodiments the outer armature engages the first member as it moves proximally, helping to open the first valve. 
   Generally, a second embodiment of a valve constructed according to the principles of this invention comprises: an electrically energizable solenoid coil having a coil axis. An outer armature is mounted relative to the coil for axially movement proximally toward and distally away from the coil, parallel to the coil axis. An inner armature inside the outer armature, and is likewise axially movable proximally toward and distally away from the coil, parallel to the coil axis. At least the inner armature is drawn proximally when the solenoid coil is energized. The assembly further comprises a first valve, having a first valve seat and a first valve member. The first valve member is movable between a closed position in which the first valve member abuts the first valve seat, and an open position in which the first valve member is spaced from the first valve seat. A first spring member resiliently biases the first valve member to its open position. 
   The valve assembly further comprises a flexible member sealingly connecting the outer armature and the first valve member to allow relative movement of the outer armature relative to the first valve member between a distal position and a proximal position. The outer armature has a flange and the first valve member has a shoulder which the flange engages when the outer armature is in its proximal position relative to the first valve member. A second spring member engaging the outer armature and resiliently biasing the outer armature to its distal position. 
   The assembly further comprises a second valve, having a second valve seat and a second valve member on the inner armature. The second valve member is movable with the inner armature between a closed position in which the second valve member abuts the second valve seat, and an open position in which the second valve member is spaced from the second valve seat. A third spring member engages the inner armature and resiliently biases the third valve member carried thereon to its closed position. 
   Energizing the solenoid coil causes the inner armature to move proximally against the bias of the third spring member, moving the second valve member to its open position, the movement of the inner armature causes the outer armature to move proximally against the bias of the second spring member so that the flange engages the shoulder on the first valve member to move the first valve member to its to its open position. In this embodiment the outer armature moves before engaging the first valve member, so that the impact of the moving outer armature helps to open the first valve. Further the inner armature is closer to its home position when it acts on the first valve member, exerting more force on the valve member to help open it. 
   Thus, coaxial valves of the present invention are of simple, inexpensive, yet reliable construction. These valves provide for the operating of large capacity valve with relatively smaller, less expensive solenoids. These and other features and advantages will be in part apparent and in part pointed out hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of a first embodiment of a gas valve constructed in accordance with the principles of this invention; 
       FIG. 2  is a enlarged cross-sectional view of the gas valve assembly of the first embodiment in the closed position; 
       FIG. 3  is a enlarged cross-sectional view of the gas valve assembly of the first embodiment in the open position; 
       FIG. 4  is a enlarged cross-sectional view of a gas valve assembly of a second embodiment in the closed position; and 
       FIG. 5  is a enlarged cross-sectional view of a gas valve assembly of the second embodiment in the open position. 
   

   Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Without intending any loss of generality, the devices and methods of this invention will be described in conjunction with gas fuel control valves, inasmuch as the invention is considered particularly advantageous when employed in such devices. It will be recognized, however, that the devices and methods of this invention may be applied more generally to various other fluids, both gaseous and liquid, and may be used advantageously to control the flow of such fluids in devices other than those that are described herein. In addition, where the discussion refers to control of a current flowing in a coil, it will be recognized that control of either current or voltage may be possible, with equivalent results. 
   A first embodiment of a gas valve constructed according to the principles of this invention is indicated generally as  20  in  FIG. 1 . Gas valve  20  may be, for example a valve for controlling the flow of natural gas to an appliance, such as a furnace or water heater or the like. The gas valve  20  comprises an inlet  22 , and an outlet  24 , and a flow passage  26  therebetween. An inlet filter screen  28  and an outlet filter screen  30  can be provided to prevent debris from entering the valve. The gas valve  20  also comprises a valve assembly  32  (shown better in  FIGS. 2–5 ), and a pressure regulator  34 . A passage  36  having an opening  38  near the inlet  22  extends to the pressure regulator  34 . 
   A control gas orifice  46 , a diaphragm  48 , a main regulator valve  50 , a servo regulator  52 , a regulator vent  54 , a by-pass path  56 , an outlet sense port  58 . The construction and operation of the regulator is well known and is disclosed in Visos et al., U.S. Pat. No. 3,727,836, incorporated by reference in its entirety. 
   Gas enters at inlet  22  and passes through filter screen  28 . When valve assembly  32  is open, gas flows through the redundant valve and is divided into two flows. One of these flows passes through the main/regulator valve  50 , the filter screen  30 , and outlet  24 , and the other flow is directed through the main valve into opening  38 , through passage  44 , past the control gas orifice  46 , and to the back of diaphragm  48 , to servo regulator  52  and servo by-pass  56 . The flows to servo regulator  52  and to servo by-pass  56  are then reunited at outlet sense port  58  and this second flow rejoins the first to pass through filter screen  30 . 
   The gas valve assembly  32  is operated by a solenoid coil  40 , having a generally central bore with a coil axis. A circuit board  42  may be provided to control the coil  40 , and a switch  43  may be provided to manually operate the coil. As best shown in  FIGS. 2 and 3 , the gas valve assembly includes an outer armature  100  axially movable proximally toward and distally away from the coil  40 , parallel to the coil axis. An inner armature  102  is disposed inside the outer armature  100 , and is axially movable proximally toward and distally away from the coil  40 , parallel to the coil axis. The inner armature  102  is made from or includes a magnetically responsive material such that it is drawn proximally when the solenoid coil  40  is energized. 
   The gas valve assembly  32  also includes a first valve  104 , having a first valve seat  106 , that may be formed in or secured on the body of the gas valve  20 . The first valve  104  also includes a first valve member  108 , which can move between a closed position ( FIG. 2 ) in which the first valve member  108  abuts the first valve seat  106 , and an open position ( FIG. 3 ) in which the first valve member is spaced from the first valve seat. A first spring member resiliently biases the first valve member  108  to its open position. In this preferred embodiment the first spring member can be coil spring  110  surrounding the first valve seat  106  and acting between the first valve seat and the first valve member  108 , although the spring member could be any other element capable of applying a force to separate the first valve seat and the first valve member. 
   The gas valve assembly  32  also includes a second valve  112 , having a second valve seat  114  on the first valve member  108 , and a second valve member  116  formed on the outer armature  100 . The second valve member  116  is movable with the outer armature  100  between a closed position in which the second valve member abuts the second valve seat  114 , and an open position in which the second valve member is spaced from the second valve seat. A second spring member engages the outer armature  100  and resiliently biases the second valve member  116  carried thereon to its closed position. In this preferred embodiment, the second spring member is a coil spring  118  which engages the outer armature and resiliently biases it in the distal direction. 
   The valve assembly  32  further comprises a third valve  120 , having a third valve seat  122  and a third valve member  124  on the inner armature  102 . The third valve member  124  is movable with the inner armature  102  between a closed position in which the third valve member abuts the third valve seat  120 , and an open position in which the third valve member is spaced from the third valve seat. A third spring member engages the inner armature  102  and resiliently biases the third valve member carried thereon to its closed position. The third spring member may be a coil spring  126 , or any suitable member for biasing the inner armature  102  in the distal direction. 
   Energizing the solenoid coil  40  causes the inner armature  102  to move proximally against the bias of the third spring member (e.g., spring  126 ), moving the third valve member  124  to its open position. This opens the passage  44 . The movement of the inner armature  102  causes the outer armature  100  to move proximally against the bias of the second spring member (e.g., spring  118 ), moving the second valve member  116  to its open position. Once the second valve member  116  is in its open position, at least some of the gas pressure is relieved and the first valve member  108  can move under bias of the first spring member (e.g., spring  110 ), to its open position. 
   The first spring member may be sufficient to open the first valve  104 , however, in stead of, or in addition to the force from the first spring member, the outer armature  100  can have a flange  127  (which may also serve as the part of the second valve member  116 ), which can engage a shoulder  128  formed on the second valve member to apply an opening force to the first valve member. The shoulder  128  is preferably spaced from the normal seated position of the flange  127 , so that when the flange engages the shoulder, the flange is moving with the outer armature  100 . This impact force contributes to the ability of the armature  100  to open the relatively larger first valve member  108 . Further contributing to the ability of the armature to move the valve member is the fact that by the time the armature engages the first valve member, the armature has moved proximally into the bore of the coil where the pulling force of the coil is greater. Thus, by utilizing one or more of: (1) relieving the pressure on the first valve by first opening the second valve; (2) the first spring member and/or the pulling force of the outer armature; (3) the impact force of the distally moving outer armature; and (4) the increased pulling force of the coil on the outer armature as it is more centrally located in the bore, the valve assembly can open a relatively large valve member with a relatively small and inexpensive solenoid coil  40 . 
   A second embodiment of a valve assembly is indicated generally as  32 ′ in  FIGS. 4 and 5 . The valve assembly  32 ′ is similar in construction to valve assembly  32 , and corresponding parts are identified with corresponding reference numerals. The valve assembly  32 ′ comprises the gas valve assembly includes an outer armature  100  axially movable proximally toward and distally away from the coil  40 , parallel to the coil axis. An inner armature  102  is disposed inside the outer armature  100 , and is axially movable proximally toward and distally away from the coil  40 , parallel to the coil axis. The inner armature  102  is made from or includes a magnetically responsive material such that it is drawn proximally when the solenoid coil  40  is energized. 
   The gas valve assembly  32 ′ also includes a first valve  104 , having a first valve seat  106 , that may be formed in or secured on the body of the gas valve  20 . The first valve also includes a first valve member  108 , which moves between a closed position ( FIG. 4 ) in which the first valve member  108  abuts the first valve seat  106 , and an open position in which the first valve member is spaced from the first valve seat. A first spring member resiliently biases the first valve member  108  to its open position. In this preferred embodiment the first spring member can be coil spring  110  surrounding the first valve seat and acting between the first valve seat  106  and the first valve member  108 , although the spring member could be any other element capable of applying a force to the first valve member  108 . 
   The gas valve assembly  32 ′ also includes a flexible boot  130  which connects the first valve seat  106  with the distal end  132  of the outer armature  100 . The distal end  132  of the outer armature  100  can engage a shoulder  128  on the first valve member  108  as described in more detail below. The distal end of  132  of the outer armature  100  is movable between a first distal position where it generally engages the first valve member  108 , and a second proximal position where it engages the shoulder  128 , and the flexible boot  130  accommodates this movement. A second spring member engages the outer armature  100  and resiliently biases the distal end  132  to its first position adjacent the first valve member  108 . In this preferred embodiment, the second spring member is a coil spring  118  which engages the outer armature  100  and resiliently biases it in the distal direction. 
   The valve assembly  32 ′ further comprises a second valve  120 ′ (similar to the third valve  120 ), having a second valve seat  122 ′ and a second valve member  124 ′ on the inner armature  102 . The second valve member  124 ′ is movable with the inner armature  102  between a closed position in which the second valve member abuts the second valve seat  122 ′, and an open position in which the second valve member is spaced from the second valve seat. A third spring member  126 ′ engages the inner armature  102  and resiliently biases the second valve member carried thereon to its closed position. 
   Energizing the solenoid coil  40  causes the inner armature  102  to move proximally against the bias of the third spring member (e.g., spring  126 ), moving the second valve member  124 ′ to its open position. This opens the passage  44 . The movement of the inner armature  102  causes the outer armature  100  to move proximally against the bias of the second spring member (e.g., spring  118 ), moving the distal end  132  of the outer armature  100  to its second position engaging the shoulder  128  on the first valve member. The impact of the moving distal end  132  on the shoulder  128  helps to release the first valve member  108  from the first valve seat  106 . The first valve member  108  can move proximally under the force applied by the distal end  132 , which is relatively strong because the inner armature  102  is closer to its home position in the coil  40 . The first valve member  108  can move under bias of the first spring member (e.g., spring  110 ), to its open position. The first spring member may be sufficient to open the first valve  104 , however, instead of, or in addition to, the force from the first spring member, the outer armature  100  can engage the shoulder  128  with the distal end  114 ′ of the outer armature  100 . 
   As noted above the shoulder  128  is preferably spaced from the normal seated position of the distal end  132  against the first valve member  108 , so that when the flange engages the shoulder, the flange is moving with the outer armature  100 . This impact force contributes to the ability of the armature to opening the relatively larger first valve member. Further contributing to the ability of the armature to move the valve member is the fact that by the time the armature engages the first valve member, the armature has moved proximally into the bore of the coil where the pulling force of the coil is greater. Thus, by utilizing one or more of: (1) the first spring member and/or the pulling force of the outer armature; and (2) the impact force of the distally moving outer armature; and (3) the increased pulling force of the coil on the outer armature as it is more centrally located in the bore, the valve assembly can open a relatively large valve member with a relatively small and inexpensive solenoid coil  40 . 
   OPERATION 
   When an appropriate AC voltage is supplied by a controller (such as a thermostat, which is not shown) and when manual switch  43  is in the “on” position, built-in rectifier circuitry (not shown) supplies rectified DC current to coil winding  40 . The current through coil  40  generates a magnetic field that is concentrated and shaped by coil brackets  62  and sleeves  60  to provide an operating force on inner armature  102 . This magnetic force is sufficient to override the third spring  126 , which provides a biasing force on the inner armature  102  in an opposite direction to the magnetic field, which pulls inner armature into coil  40 . Inner armature  102  slides within outer armature  100  (which may be non-magnetic) and moves towards the closed end of outer armature  100 . This movement lifts the valve member  124  off its seat  122 , thereby opening passage  44 . 
   In the first embodiment, the outer armature  100  moves proximally with the inner armature  102 , moving the valve member  116  from the valve seat  114  of the second valve  112 . This relieves the pressure, so that spring  110  can move the first valve member  108  off of first valve seat  106 . In addition, the flange  127  on the distal end of the outer armature  100  strikes and engages the shoulder  128  on the first valve member  108  to help move the first valve member off of the first valve seat  106  and open the first valve  104 . 
   In the second embodiment, the outer armature  100  moves proximally with the inner armature  102 . The flexible boot  132  accommodating the movement of the proximal end of the outer armature  100 . By the time the moving end  132  of the outer armature  100  strikes the shoulder  128  of the first valve member  108 , the impact helps move the first valve member off of the first valve seat  106 . Continued pulling form the outer armature and the first spring  110  help open the first valve  104 . 
   The pressure differential between the inlet and the outlet causes gas to flow through the open path  44  to the control gas orifice  46 . The limited amount of gas coming through the control gas orifice  46  is split into two paths, one going to the servo diaphragm  64  and one going to the back of the regulator diaphragm  48 . Pressure differential caused by the gas going to the back of the regulator diaphragm  48  forces the diaphragm to flex, pushing against a regulator shaft. This force overrides a regulator spring and the regulator shaft lifts a regulator valve off its seat, allowing high capacity regulated flow from the inner chamber  26  to outlet  24 . 
   As long as appropriate current is supplied, the forces on the inner and outer armatures  100  and  102  remain in equilibrium and high capacity flow is allowed from inlet  22  to the inner chamber  26 . Gas flow to outlet  24  is regulated by a balance of pressures. This balance is adjustable and controlled by the regulator  52 . The regulator  52  controls the position of the regulator diaphragm  48 , which in turn controls the position of the regulator valve. The position of this valve relative to its seat controls the flow of gas from inlet  22  to outlet  24 . The effect of fluctuations in the inlet pressure within the specified range of operation are damped and effectively eliminated by this system. The inlet filter  28  and the outlet filter  30  prevent particles from entering the valve and interfering with proper operation. 
   When current to the valve coil  40  is interrupted, either by the controller (e.g., the thermostat interrupts AC voltage) or by turning off the manual switch  43 , the magnetic field collapses. Breaking the force equilibrium that holds the valves off their seats (first valve  104  and third valve  120  in the first embodiment; first valve  104  and second valve  120 ′ in the second embodiment), and the return springs  118  for the first valve and  126  for the third valve in the first embodiment, and  118  for the first valve and  126 ′ for the second valve in the second embodiment. Closing redundancy is achieved by the independent closing of the two valves  104  and  120  in the first embodiment, and  104  and  120 ′ in the second embodiment, the closing of either of which is separately capable of shutting off the gas flow. Valves  120  and  120 ′ shut off the gas flow by closing against its seat  122 . Valve  104  shuts of gas flow by closing off gas path  26 . 
   It will thus be seen that the solenoid valve constructions of this invention having a single coil with co-axial armatures and a valve on each armature at the same side of the solenoid valve is useful to provide a redundant valve construction in a smaller space than previously known for structures having similar function. Two mechanically independent valves may be provided in a small space, both of which are supplied with an operating flux from a single coil. Those skilled in the art will recognize that the inventive solenoid valves of this invention may be useful in many applications and for control of many different types of fluids, and are especially useful for control of gaseous fuel flow. Inasmuch as many modifications within the spirit of the invention will be apparent to those skilled in the art, the scope of the invention should be determined by reference to the claims appended below and the full scope of equivalents as provided by applicable laws.