Abstract:
An improved solenoid valve assembly for controlling fluid flow having a valve body with an inlet and outlet, a diaphragm assembly with passages for providing fluid communication between the inlet and the outlet, and a movable seal pad responsive to an external signal for controlling flow through one of the passages. The improvement has the diaphragm assembly including a symmetrical fluid flow restrictor movable within the valve body, with a head portion, an intermediate portion and a guide portion surrounding a main body portion. The head portion has a fist end of the pilot passage which extends through the main body portion. The intermediate portion includes an annular extension with an upper side and a lower side. The guide portion has a plurality of legs extending from the main body portion for a distance substantially equal to the outer diameter of the annular extension, and is spaced from and interconnected with the intermediate portion by reduced diameter gullet portion.

Description:
CROSS-REFERENCE TO RELATED CASES 
     The present application claims the benefit of the filing date of U.S. Provisional application Ser. No. 60/460,168, filed Apr. 3, 2003, the disclosure of which is expressly incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The field of art to which this invention pertains includes that of solenoid valve assemblies and particularly to diaphragm assemblies for controlling the rate of flow therethrough. 
     BACKGROUND OF THE INVENTION 
     Valves are used to control the flow of fluids for various applications involved in hydraulic systems. For example, valves are used in the fuel dispensing market in order to provide and meter a proportional fluid flow of fuel One such valve is a pilot operated solenoid valve. 
     Typically these solenoid valves have an integrated diaphragm assembly moveable within the valve body of the solenoid valve. The diaphragm assembly is comprised of a diaphragm and a restrictor that can open and close a main passage between the solenoid valve inlet and outlet. In these designs, one side of the diaphragm is exposed to inlet fluid pressure and the opposite side of the diaphragm forms a chamber for receiving pressurized fluid. A solenoid, or alternatively an actuator, controls a pilot seal that blocks flow through a central pilot passage in the diaphragm assembly. The diaphragm assembly moves when the pressure differential acting on both sides of the diaphragm is sufficient to overcome forces, e.g. a spring, exerted on one side of the diaphragm. The diaphragm has a bleed passage allowing fluid to flow from the inlet into the chamber. 
     To open the valve and allow fluid to flow directly from the inlet to the outlet, the diaphragm must be moved off of a seat in the main valve body. Upon opening of the pilot passage, the main passage also opens and allows direct fluid communication between the solenoid valve inlet and outlet. It is imperative for many applications that the opening and closing of the main passage be conducted proportionally. This proportional opening and closing should be directly based on the actuation of the solenoid by the end user. It is difficult to control the proportional flow due to binding of the restrictor with the main valve body. Binding of the restrictor can cause no response after actuation or a quick response when the restrictor becomes unbound and suddenly roves. 
     Diaphragm assemblies having restrictor with multiple components can bind within a valve bore preventing movement of fluent movement of the diaphragm assembly. A multiple component restrictor could have a separate orifice body, flange portion, and guide portion. It is advantageous to have similar outside diameters for the flange and guide portions. When separate components are used, it is less likely that these two dimensions will be the same. Extra assembly steps are needed to sort through the component pieces in order to find components with similar dimensions. Tolerances on these parts can allow some deviance, which must coincide for all parts in order to produce a restrictor having a flange and guide with similar outer diameters. It is also much easier to manufacture the one-piece restrictor, rather than one with several pieces. 
     Diaphragm assemblies made of one piece can also stick within the valve bore when inlet radial fluid flow comes in contact with the guide of the restrictor. This contact can cause the restrictor to tilt relative to the longitudinal axis of the valve, and bind within the valve bore. This can occur with an open valve when the guide of the restrictor is in the radial path of the inlet fluid flow. Prior art references such as U.S. Pat. No. 5,299,775 to Kolze, U.S. Pat. No. 5,655,747 to Pasut, and U.S. Pat. No. 5,732,929 to Luppino et al. all show diaphragm assemblies with guides that come in contact with radial inlet fluid flow. These prior art designs can bind within the valve bore due to this contact. 
     SUMMARY OF THE INVENTION 
     The present invention provides a diaphragm assembly for use in a solenoid operated valve. The diaphragm assembly has a restrictor used in controlling fluid flow. The invention overcomes the obstacle of manufacturing and assembling a multiple piece restrictor and provides a single piece restrictor that controls fluid flow more proportionally. 
     A feature of the present invention is to provide an improved solenoid valve assembly for controlling fluid flow. The solenoid valve assembly is comprised of a valve body having an inlet and an outlet, a bore defining a main fluid passage in communication with the inlet and outlet, and a valve seat located on an innermost end of the bore between the inlet and outlet. The assembly further includes a diaphragm assembly, interposed between the valve body and a valve body cover and located between the inlet and outlet. The diaphragm assembly is engagable with the valve seat and movable for contacting the seat and closing the main fluid passage, as well as defining a chamber with the valve body. A passage within the diaphragm assembly provides fluid communication between the inlet and the chamber. A pilot passage in the diaphragm assembly provides fluid communication between the chamber and the outlet. A movable seal pad responsive to an external signal controls flow through the pilot passage. The diaphragm assembly includes the generally symmetrical fluid flow restrictor, movable within the valve body main fluid passage. The restrictor has a head portion, an intermediate portion and a guide portion surrounding a main body portion that has a pilot passage extending therethrough. The head portion has a first end of the pilot passage integrated therewith. The intermediate portion includes an annular extension with an upper side and a lower side. The guide portion has a plurality of legs radially extending from the main body portion for a distance substantially equal to the outer diameter of the annular extension. The guide portion is spaced from and interconnected with an intermediate portion by a reduced diameter gullet portion. 
     Another feature of the noted assembly includes having the annular extension being substantially cyclically. A further feature includes having an inwardly angled lower portion of the outer surface. Still a further feature has the longitudinal extent of the gullet portion being equal to or less than the maximum travel distance of the restrictor minus the longitudinal extent of the annular extension. Another feature includes having the head portion with a central cavity adapted for receiving an orifice body. 
     Still yet another feature of the noted assembly has the radial distal end portions of the plurality of legs being interconnected via a continuous, circular, annular perpheral portion. A firer feature has the annular peripheral portion having an outer diameter substantially equal to the outer diameter of the annular extension. Another feature has the outer diameter of the annular peripheral portion being slightly less than the diameter of the valve body main fluid passage. 
     Another attribute of the noted assembly has the diaphragm pilot passage with a diameter greater than that of the passage between the inlet and the chamber. A further attribute of the noted assembly has the main body portion, the head portion, the annular flange and the guide portion being of a one-piece construction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a downwardly-directed perspective view of a one-piece, hollow piston-type restrictor according to one embodiment of the present invention. 
     FIG. 2 is an upwardly-directed perspective view of the restrictor, of the restricted FIG.  1 . 
     FIG. 3 is a bottom view of the restrictor according to the present invention. 
     FIG. 4 is a longitudinal cross-sectional view of the restrictor taken along line  4 — 4  in FIG.  3 . 
     FIG. 5 is an enlarged view of a portion of the restrictor flange taken along encircled portion  5 — 5  in FIG.  4 . 
     FIG. 6 is an enlarged view of the restrictor orifice taken along encircled portion  6 — 6  in FIG.  4 . 
     FIG. 7 is a top view of the one-piece restrictor having an orifice press-fitted therein. 
     FIG. 8 is a longitudinal cross-sectional view of the one-piece restrictor, with the press fitted orifice, taken along line  8 — 8  in FIG.  7 . 
     FIG. 9 is a longitudinal cross-sectional view of a portion of a solenoid valve having the one-piece restrictor of the present invention assembled there within. 
     FIG. 10 is a longitudinal cross-sectional view of a further embodiment of the present invention, detailing a one-piece restrictor with an integrated orifice, taken along line  10 — 10  of FIG.  11 . 
     FIG. 11 is a bottom view of the further embodiment shown in FIG.  10 . 
     FIG. 12 is a longitudinal cross sectional view of a prior art, multiple piece restrictor attached to a diaphragm. 
     FIG. 13 is a graph showing measures of flow, in counts, taken at different positions of pluralities of values utilizing prior art restrictor, responding to amperages, while the restrictor are moving to an open position. 
     FIG. 14 is a graph similar to that shown in FIG.  13  and including the measures of flow while the values utilizing the prior art retractors are also closing. 
     FIG. 15 is a graph similar to that shown in FIG. 13 but for pluralities of values utilizing restrictors according to the present invention. 
     FIG. 16 is a graph similar to that shown in FIG. 14 but for pluralities of values utilizing restrictors according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings and particularly to FIGS. 1,  2  and  4 , there is shown a hollow piston-type restrictor  10  of a one-piece construction Restrictor  10  includes a main body portion  12 , a circular flange or piston  20  and a multi-legged guide  30  having a similar, substantially equally dimensioned outside diametrical surface as said flange  20 . A gullet or stepped neck portion  35  longitudinally separates flange  20  from guide  30 . The extreme end, or top, of restrictor  10  includes a head portion  45  having a stepped bore  47 , as best seen in FIG. 6, within its center. Bore  47  merges into a coaxial center passage  52  that extends freely longitudinally from bore  47  to the opposite end of restrictor  10 . Passage  52  has a uniform diameter and is coaxial with the longitudinal axis of restrictor  10 . Passage  52  is surrounded, and formed by, main body portion  12  throughout its longitudinal extent. Referring to FIG. 8, bore  47  is adapted to receive an orifice body  60  that is press fitted thereinto. 
     Referring to FIG. 3, guide  30  is shown having three, preferably equally spaced, legs  31  radially extending from the center of restrictor  10 . As mentioned above, the outer diametrical surfaces of guide legs  31  are substantially equal to and co-planar with the outer diameter of flange  20 . Guide  30  thus has a plurality of curved outer edge or peripheral surfaces  32  which are dimensioned so as to be closely received within an inner cylindrical bore  86  of a valve body  85 , the latter forming a part of a solenoid valve  80 , a portion of which is shown in FIG.  9 . The curvature of leg outer edge surfaces  32  is also substantially similar to that of the outer periphery of flange  20 . As best shown in FIG. 2, each leg  31  of guide  30  has opposed curved shapes so that the connecting surfaces  34  between adjacent legs  31  form an outline of an arc portion of a partial cylinder. 
     Referring to FIGS. 4 and 5, flange or piston  20  has an outer peripheral surface  22  with a substantially cylindrical shape. Peripheral surface  22  is comprised of a longitudinally flat portion x that terminates into an angled, or arced, portion y, at its lower edge, having an angle z, for example, in the range of 7° to 15°, and more specifically of 12° relative thereto. Flange  20  has parallel flat upper and lower surfaces  23 ,  24  respectively. 
     Referring now to FIGS. 10 and 11, a further embodiment of the present invention is shown. A restrictor  110  similar to restrictor  10 , discussed above, is detailed with two notable differences. Restrictor  110  includes an integral orifice  160  with a pilot passage  162  that are formed as part of the one-piece construction. This differs from restrictor  10  that uses a separate component for its orifice body  60 . The other distinguishable feature is the design of its guide  130 . Unlike guide  30 , discussed above, guide  130  includes a continuous, circular, outer peripheral hoop portion  132 , connecting adjacent legs  131 . Outer peripheral portion  132  includes a peripheral surface  133  having a cylindrical shape and dimension so that it is adapted to be closely received within solenoid valve cylindrical bore  86 . 
     Referring to FIG. 12, a prior art diaphragm assembly  210  is shown in cross-section. Diaphragm assembly  210  is comprised of a restrictor body  212 , a separate restrictor annular portion  214 , a guide  216 , a nut  218 , an orifice body  220 , a diaphragm  222 , and a retainer  224 . In contrast thereto, the present invention has combined restrictor body  212  and restrictor annular portion  214  into one-piece restrictor in first embodiment  10 , and has further integrated orifice body  220  into this one-piece construction in further embodiment  110 . One of the significant differences between the present invention, including both embodiments  10 ,  110 , and the prior art construction is that prior art guide  216  and restrictor annular portion  214  are juxtaposed and thus do not have a gap separating same. Referring specifically to FIG. 4, gullet  35  longitudinally displaces and separates guide  30  from flange  20 . The same difference exists with restrictor  110 , shown in FIG. 10, which has gullet  135 . 
     The operation of the present invention will now be discussed. Solenoid valve  80  performs as a two-stage valve. The first stage is represented by fluid flow through passage  52  in restrictor  10 . The second stage allows fluid to flow through bore  86  of valve body  85 . Referring to FIGS. 8 and 9, fluid enters solenoid valve portion  80  through an inlet  81 , travels through a hole or passage, not shown, in a diaphragm  70  and enters a chamber  83  located inwardly of diaphragm  70 , the latter being interposed between valve body  85  and a valve body cover  84 . When the solenoid actuator (not shown) is activated, a current is provided through a magnetic field (not shown), and begins to move an armature  88  longitudinally, thus overcoming the force of an opposing closing spring  91 . When armature  88  moves, a stop, or seal pad  89  is moved away from orifice body  60  thereby allowing fluid, in chamber  83 , to vent from chamber  83  into a pilot passage  62  in orifice body  60  and travel through passage  52  in restrictor  10 . When fluid begins to exit chamber  83  at a rate faster than it is entering, fluid pressure is relieved on that side of diaphragm  70 . This relief in fluid pressure causes diaphragm  70 , and thus restrictor  10 , to move. Pilot passage  62  has an area larger than that of the hole (not shown) in diaphragm  70  so that more fluid is entering passage  52  than is filling chamber  83 , thus ensuring a drop in fluid pressure. 
     Prior to the movement of diaphragm  70 , fluid entering inlet bore  81  is prevented from directly entering inner cylindrical bore  86  of solenoid valve portion  80  by the sealing position of diaphragm  70  on the axial edge of valve body top portion  87 . Once diaphragm  70  begins its initial inward movement, the majority of fluid flow entering inlet bore  81  is still prevented from entering cylindrical bore  86  by the sealing position of flange  20  against inner bore  86 . Since the outside diameter of flange  20  is nearly the same, and only very slightly less than the inside diameter of inner bore  86 , outer edge surface  22  is in close contact with the surface of inner bore  86  and substantially prevents fluid from entering bore  86 . Referring now to FIGS. 4,  5  and  9 , as the current through the magnetic field is increased and restrictor  10  moves longitudinally inwardly, fluid begins to pass through the interface between surface  22  and bore  86  when angled portion, z, of surface  22  lines up with a top portion  87  of valve body  85 . It should be noted that a small amount of fluid flows through the small gap, or annulus, created between flange  20  and the surface of inner bore  86  when restrictor  10  is not roved. The amount of fluid flow increases when restrictor  10  moves, as noted, so that angle portion z becomes adjacent with valve body top portion  87 . The amount of fluid flow is significantly increased when flange  20  is completely longitudinally inwardly of top portion  87 . In this position, gullet  35  is adjacent top portion  87 , providing a flow path for the fluid. The further restrictor  10  travels longitudinally inwardly, the more flow is allowed to pass. When restrictor  10  fully completes its inward stroke, a full flow of fluid enters inner bore  86 , flows past guide  30  and exits solenoid valve portion  80  at an outlet bore  94 . 
     By slowly increasing the gap, or annulus, between restrictor  10  and valve body  85 , with outer edge surface angled portion z, followed by the unencumbered gullet  35 , fluid flow is proportionally increased and does not experience a sudden increase in flow as is experienced with the prior art design shown in FIG.  12 . Guide  216  in prior art design diaphragm assembly  210  is in abutting contact with annular portion  214 . In operation, when annular portion  214  travels inwardly and passes beyond valve body top portion  87 , fluid flow from inlet  81  comes into contact with guide  216 , rather than gullet  35  as is the case in the present invention. Initially this fluid flow radially contacts guide  216  and can thus force guide  216  to shift laterally. Guide  216  restricts the fluid flow into bore  86  by starving off flow at the location where the legs (not shown) are adjacent to valve body top portion  87  while allowing full flow at the location between the legs. This unbalanced flow, and force, cause guide  216  to move, shift, or flop, in the radial or lateral direction. Since there is but a small clearance between the distal surface of the guide legs and bore  86 , the unimpeded fluid flow will radially shift guide  216  so that the distal end of the guide legs come into contact with the surface of bore  86 . This shift, and contact, will in turn, cause an erratic longitudinal movement of guide  216  within bore  86 , and even intermittent and/or complete binding of guide  216  within bore  86 . Erratic longitudinal movement of guide  216  can cause sudden increases in flow through the solenoid valve. Binding of guide  216  within bore  86  can cause the solenoid valve to remain open after the deactivation of solenoid actuator. Upon the deactivation of the actuator, closing spring  91  is designed to return restrictor  10  and diaphragm  70  to the closed position wherein diaphragm  70  rests on valve top portion  87  and restrictor flange upper surface is adjacent top portion  87 . Both erratic movement and binding will seriously diminish the functionality of a solenoid valve. 
     The stroke of restrictor  10  starts from a resting position in which flange  20  is radially adjacent valve body top portion  87 . Specifically, flange upper sur  23  is not axially inward of top portion  87  so that the entire flange outer edge surface  22  is within valve body cylindrical bore  86 . This position is indicative of solenoid valve  80  being closed and ensures, by means of diaphragm  70  covering valve body top portion  87 , that flow from inlet  81  does not enter cylindrical bore  86 . As diaphragm  70 , and thus restrictor  10 , begin their axially inward movement, fluid flow entering inlet  81  can enter cylindrical bore  86 . When solenoid valve  80  is completely open, the stroke of restrictor  10  ends before any portion of guide  30  is axially inward of valve body top portion  87 . In this completely open position, radial fluid flow from inlet  81  does not contact guide  30 , thus preventing any shifting of restrictor  10 . 
     The improved fluid flow through the valve is illustrated in FIGS. 13-16. These graphs show the flow of air, in counts, versus longitudinal movement of the restrictor, shown in milliamps. Air is chosen as the testing medium for several reasons. First, a typical application medium with which the present invention, and prior art, find utility is gasoline. For many reasons, including safety, testing is not performed with gasoline. There are alternative wet testing media, but they all present problems with cleanliness and ventilation. Therefore, air is used and has proven to be proportional with applicable media. Additionally the present invention can be applied for gas or air metering. 
     In FIG. 13, fluid flow for opening up prior art valves, such as that shown in FIG. 12, is shown. As illustrated, fluid flow tends to jump dramatically instead of exhibiting the desired, smooth proportional change in flow. Likewise, in FIG. 14, a multi sample test is shown, not only with the valve opening, but also coming back down (closing). In this case, the opening movement of the valve shows the same spike as in FIG. 13, but flow from the closing movement is not shown in several samples since the valves never closed. Due to difficulties in maintaining the proper tolerances with the prior art, multi-component design, the finished O.D. of prior art guide  216  tends to fall outside of the required design tolerance. An out of specification O.D., e.g. too small, will cause guide  216  to stick within the valve bore. Of the several valve samples shown in FIG. 14, only one is shown to retreat to a minimal flow (close to 0 counts) and this sample has a severe flow drop-off at about 190 milliamps. 
     FIG. 15 shows a multi sample test of the proportional fluid flow as the present invention restrictor moves inwardly. Unlike the graphs of the operation and the prior art construction (FIGS. 13 and 14) which exhibit an immediate, sharp rise in fluid flow when restrictor annular portion  214  passes valve body top portion  87 , the present invention provides a proportional increase in fluid flow as restrictor  10  moves to a fully open position (at 520 milliamps). Initially, in the range from 180-280 milliamps, a limited amount of fluid flow passes through orifice body  60 , when stop pad  89  is lifted off orifice body  60 , and through the gap, or annulus, created between the O.D. of flange  20  and the I.D. of inner cylindrical bore  86  of valve body  85 . This fluid flow increases, and is shown as the first ramped portion in the graph at about 290 milliamps, when angled, z, outer edge surface  22  of flange  20  is adjacent to valve body top portion  87 . As gullet  35  portion passes valve body top portion  87 , more medium is permitted to pass through valve body  85  and exit outlet  94 . It should be noted that a top portion  33  of guide  30 , seen in FIG. 1, never reaches the location adjacent to valve body top portion  87 . Therefore, the present invention does not experience or exhibit the shifting, or binding, of guide  30  within bore  86 . All of the medium flows longitudinally past guide  30  through bore  86  and does not initially radially or laterally contact guide  30  as is the case in the prior art construction. This is shown in the steady sloped portion of FIG. 15, prior to reaching the upper plateau in which solenoid valve  80  is fully open. 
     FIG. 16 shows a graph of fluid flow (counts) versus longitudinal movement of restrictor (milliamps). Similar to that shown in FIG. 15, the inward movement of restrictor  10  produces a proportional increase in fluid flow. Unlike FIG. 14 (prior art), the return movement also produces a proportional decrease in the medium flow. 
     Embodiment  110 , shown in FIGS. 10 and 11, produces the same proportional flow as embodiment  10  discussed above. Gullet  135  provides the same benefits as those exhibited with restrictor  10 . Guide  130 , with its circular, or hooplike, design has an outer diameter substantially equal to that of flange  120 . Since guide  130  has a hoop-like design, a plurality of flow channels  165  are created between legs  131 . 
     It should be noted that with the one or two-piece designs of the present invention, manufacturing thereof is much more precise. Compared with prior art designs, such as that shown in FIG. 12, which have at least three components (guide  216 , restrictor annular portion  214 , and orifice body  220 ), the present invention has reduced the componentry to two parts, as in embodiment  10 , and to but one part, as in embodiment  110 . By reducing the number of components, tolerance variances, including concentricity problems, are also reduced. Most notably, since guides  30 ,  130  and flanges  20 ,  120  respectively are integrated into a unitary piece, it is much easier to maintain substantially the equal outside dimensions of both. The substantially equal outside dimensions and curvatures provide smoother movement and operation of restrictors  10  and  110 . With multiple pieces, a fabricator has to selectively sort through the pieces in order to provide for a restrictor/solenoid assembly with desired clearances. Although not shown, embodiment  10  can have integrated orifice body, similar to that shown with restrictor  110 , further simplifying the manufacture and assembly of restrictor  10 . If so desired, embodiment  110  can utilize the separate orifice  60  of embodiment  10 .