Abstract:
A two-stage fluid pressure regulating valve has a solenoid operated lever for moving a regulator shaft between two positions. The regulator shaft biases the regulator spring of a flow rate control diaphragm valve. When the solenoid is actuated the lever is pivoted, applying increased force to the regulator spring, to change the valve set point to its higher pressure output. A return spring returns the arm to the low pressure set point when the solenoid is de-energized. A pair of adjustable stops are positioned for engagement by the lever and forming limits for its motion, for independently adjusting the low and high pressure set points for the valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO “MICROFICHE APPENDIX” 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to fluid pressure regulating valves, and more specifically to two-stage servo gas pressure regulators convertible to separate output pressure ranges, such as those typically used in natural and LP fuel gas controls. 
     2. Background of the Invention 
     Fluid pressure regulating valves are widely used in a number of applications. One important application is in the control of gas pressure in gas heating appliances. Typically the heat output such appliances is controlled by metering the combustion gas through an orifice operating on a known and controlled pressure drop. Because the supply conditions for the gas may vary, a pressure regulating valve is used to achieve the known pressure drop, and therefore a known gas flow to the burner. Usually a spring reference is used for maintaining the constant pressure drop, and a service adjustment is provided for fine tuning the regulated pressure. Also, single-stage valve designs are known which facilitate replacement of the reference spring to permit valve conversion for operation with different gases having different characteristics, for example, natural gas and LP gas. 
     Two-stage gas regulators are used to switch the pressure regulation, and hence the burner heat output, between a low pressure and a higher pressure regulation point. This is often accomplished by a solenoid energized by the heating system control. 
     Many types of regulating valves have been provided in the prior art to accomplish these tasks. Some have used multiple regulators in one housing, which can lead to complex and expensive assembly. Others have used complex linkages for internal adjustments. Others have provided high and low adjustments which are interrelated, complicating the adjustment process. However, no known two-stage valve designs readily permit reference spring replacement to provide for simple conversion for operation with different gases. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a pressure regulating valve with two-stage operation and independent adjustability of low and high regulated pressures. According to the present invention there is provided a regulating valve having a valve housing defining a valve seat and a flow rate control diaphragm mounted in the housing proximate the valve seat for controlling flow therethrough as a function of extension of a regulator spring located between the diaphragm and a spring retainer. Position of the retainer relative to the valve seat is controlled in part by an actuator through a linkage including a pivoting lever. A pair of adjustable stops are positioned to engage the lever and establish limits for its motion, thereby providing the low and high pressure set points for the valve. 
     The lever may be mounted on a removable cap on the housing, removal of which permits removal of a shaft which carries the regulator spring. The lever may be of a T-shaped configuration, with the shaft, solenoid and stops engaging individual projecting portions of the lever to achieve a compact assembly in which adjustments and conversion are facilitated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a pressure regulating valve according the applicant&#39;s invention, with portions broken away to show construction of a two-stage regulator used therein; 
     FIG. 2 is an enlarged view of the linkage including a lever, used in the valve of FIG. 1; 
     FIG. 3 is a top view of the servo regulator portion of the valve of FIG. 1; 
     FIG. 4 is a sectional view taken along line  4 — 4  in FIG. 3; and 
     FIG. 5 is an enlarged sectional view of the servo valve portion of the valve of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the FIG. 1, reference numeral  10  generally identifies a fluid pressure regulating valve having a portion of its housing assembly  11  broken away along line  12  to illustrate, in the right-hand side of the Figure, components relevant to the two-stage module of the present invention. Reference number  13  identifies a conventional diaphragm-type servo valve (shown in greater detail in FIG.  5 ), which regulates the control pressure for a main flow control valve according to the force of regulator spring  14 . As shown in FIG. 5, one end of this spring bears against a diaphragm assembly  15  which carries a servo valve closure member  16 . The other end of regulator spring  14  is secured on a spring retainer  21  on one end of a shaft  20  slideable in housing assembly  11  along an axis  22  toward and away from a servo valve seat  23 . 
     As is explained in greater detail hereinafter, shaft  20  is part of a linkage through which the compression of regulator spring  14  may be varied, in part by an actuator, such as a solenoid  25 . When shaft  20  is permitted to move to its upward limit (as seen in FIG.  1 ), spring  14  applies a minimum force to diaphragm assembly  15 , corresponding to a low pressure set point. When shaft  20  is moved to its downward limit, spring  14  is compressed, resulting in application of a higher force to diaphragm  15 , corresponding to a high pressure set point. 
     The two-stage regulator module includes separable housing portions, including a main housing  30  and a cover  32 . Main housing  30  may be attached to the remainder of housing assembly  11  by screws or other fastening devices (not shown), and may be designed to replace the cover of an existing single-stage valve of the general type of valve  10 , so that it can be field-converted to two-stage operation. 
     The actuation force for moving shaft  20  to the high pressure set point position is provided by solenoid  25  or other actuator. Solenoid  25  includes a two part frame  42 , of which one part is attached to the side of main housing  30 . Solenoid  25  also has an excitation coil  44 , which is connected to a switchable source of electrical power, through a heating control system (not shown). Solenoid  25  includes armature or plunger  46  having an extension  48  which projects into housing  30  to engage a lever  50  mounted for pivotal movement about an axis  51  transverse to axis  22 . 
     As seen in best in FIGS. 2 and 4, lever  50  is of a generally T-shaped configuration, and has arms  52  and  54  extending in opposite directions from axis  51 , and a leg  56  extending from axis  51  perpendicular to arms  52  and  54 . Note that lever  50  appears L-shaped in FIG. 1 because the section is taken through the center of solenoid  25  which is offset along axis  51  from arm  54 . 
     Lever  50  is pivotally attached by a pin  60  between a pair of support projections  33  formed on the underside of cover  32 . Adjustable stops, in the form of screws  53  and  55 , are provided to limit pivotal movement of lever  50 . As seen in FIG. 3, screws  53  and  55  are positioned at an angle to the axis of solenoid  25 , and for that reason screw  55  does not appear in FIG. 1, but does appear in FIGS. 2 and 4, where extension  48  of solenoid armature  46  appears behind screw  55 . 
     Screw  53 , which controls the low pressure setting, is received in a threaded aperture in cover  32  so that screw  53  may be adjusted from the exterior of the cover to determine the point of contact of arm  52  with the screw. Likewise, screw  55 , which controls the high pressure setting, is received in a threaded aperture in cover  32 , so that screw  55  may also be adjusted from the exterior of the cover to determine the point of contact of arm  54  with the screw. Reference numeral  34  identifies a vent fitting in cover  32 . 
     The underside of arm  52  bears on the top end of regulator shaft  20 . Extension  48  of the solenoid armature, when actuated, pushes against leg  56  of lever  50 . A spring  58 , shown captured on screw  55 , biases lever  50  in a clockwise direction, as seen in FIGS. 2 and 4. This serves as a return spring for solenoid armature  46 , although it will be appreciated that the return spring function could be provided equally well with a variety of different spring configurations and/or locations. 
     In operation, when solenoid  25  is unenergized, lever  50  is rotated to its clockwise (as seen in FIGS. 1,  2  and  4 ) limit by the action of return spring  58 . Regulator spring  14 , through regulator shaft  20 , also tends to rotate lever  50  in a clockwise direction. However, it is considered preferable to include a separate return spring, rather than to rely on the regulator spring alone to return the solenoid armature . The clockwise limiting position is set by contact of arm  52  with screw  53 . In this position, as shown in FIGS. 1,  2  and  4 , valve  10  is set for its low pressure output. Specifically, the position of shaft  20  is determined by the setting of screw  53 , which, in turn, determines the low pressure set point of the valve. 
     When solenoid  25  is energized, extension  48  causes lever  50  to rotate in a counter clockwise direction until arm  54  contacts screw  55 . This counter clockwise motion pushes shaft  20  downward, and increases the force of regulator spring  14  on diaphragm  15 . In this state valve  10  is set for its high pressure output. Specifically, the position of shaft  20  is determined by the setting of set screw  55 , which, in turn, determines the high pressure set point of the valve. 
     It should be noted that although a solenoid is shown and described for causing lever  50  to pivot, other types of actuators could be used to perform the same function. For example, lever  50  could be driven by a rotary actuator extending along axis  51 . 
     One advantage of the applicant&#39;s design is that adjustment of the low and high pressure output settings can be made from the exterior of valve  10 , without requiring disassembly. Further, adjustments of the low and high pressure settings are entirely independent of one another. Thus, adjustment of the settings can be made in any order, and one setting can be adjusted without necessitating readjustment of the other setting. 
     A further advantage of the above-described design is that it facilitates conversion of the valve from settings appropriate for one fuel to settings appropriate for a different fuel. This conversion generally requires replacement of regulator spring  14 . Such replacement is easily accomplished by removal of cover  32 , which also results in removal of lever  50 . This provides access to shaft  20  which may be removed with regulator spring  14  by pulling the shaft out along access  22 . Spring  14  may then be replaced with a spring having a different spring constant which will produce output pressures appropriate for the desired type of fuel. The regulator portion of the valve is then easily reassembled with the new regulator spring. 
     Although a specific embodiment of a diaphragm valve with the applicant&#39;s unique two-stage servo regulator module has been shown and described for illustrative purposes, a number of variations and modifications within the applicant&#39;s contemplation and teaching will be apparent to those skilled in the relevant arts. The invention for which protection is sought is not to be limited by the disclosed embodiment, but only by the terms of the following claims.