US3090592A - Stepped-opening diaphragm gas valve - Google Patents

Description

y 1963 T. P. FLEER STEPPED-OPENING DIAPHRAGM GAS VALVE Filed May 18, 1959 HIS AGENT United States Patent 3,090,592 STEPPED-OPENING DIAPTRAGM GAS VALVE Thomas P. Fleer, Aflton, Mm, assignor, by mesne assignments, to White-Rodgers Company, a corporation of Missouri Filed May 18, 1959, Ser. No. 813,363 5 Claims. ((11. 251-30) This invention relates generally to diaphragm-type gas valves in which biasing means is effective to hold the valve closed when gas line pressure is applied to both sides of the diaphragm and in Which the valve is opened against the biasing means by dropping the pressure on one side of the diaphragm to atmospheric. More particularly, the invention relates to the incorporation of means to efiect a stepped-opening movement in valves of this type wherein the valve in caused to move from its closed posi tion in an opening direction a predetermined initial amount at a relatively rapid rate and thereafter to continue to move openward to its full open position at a relatively slow rate. The purpose of this manner of valve operation is to provide an immediate limited flow of fuel to a gas burner, thereby to provide for the establishment of initial limited combustion in a burner combustion chamber and to delay a full flow of fuel to the burner long enough to permit the development of suflicient natural draft through the combustion chamber to support its combustion.

An object of the invention is the provision of simple, reliable, and novel means for efiecting a stepped-opening operation of a diaphragm gas valve wherein the valve is caused to move openward from its closed position a predetermined initial amount at a relatively rapid rate and then continue to move openward to its fully open position at a relatively slow rate.

A further object is to provide stepped-opening means in a diaphragm valve whereby the extent of the initial rapid moving portion of the valve opening movement may be varied and whereby the speed of the relatively slow moving portion of the valve opening movement may be varied.

More specifically, it is an object to provide a diaphragm gas valve in which line pressure existing in the fuel conduit on the upstream side of the valve and atmospheric pressure existing on the downstream side of the valve when it is closed are applied to opposite sides of the diaphragm to effect a rapid partial opening movement of the valve, and in which restricted communication between the low pressure side of the diaphragm and atmospheric pressure exterior of the fuel conduit is provided to eiiect continued opening movement of the valve to its full open position at a relatively slow rate after the pressure differential in the fuel conduit between the upstream and downstream sides of the valve drops to an inoperative value due to the partial opening of the valve.

Further objects and advantages will appear from the following description and accompanying drawing.

The single FIGURE of the drawing is a longitudinal cross-sectional View of a diaphragm gas valve constructed in accordance with the present invention.

Referring to the drawing, numeral indicates a valve body having an inlet chamber12, an outlet passage 14, and a partition 16 which separates the inlet chamber from the outlet passage. The partition is provided with a port 18 formed with an annular valve seat 20. The valve body 10 is provided with a cover 22 attached thereto by screws 24. The cover 22 has a chamber 26 formed therein lying opposite the inlet chamber 12 in the valve body, and a flexible diaphragm 2S clamped at its periphery between the valve body 10 and cover 22 forms a flexible movable wall dividing chambers 12 and 26. Attached to the central portion of diaphragm 23, and on its lower 3,999,592 Patented May 21, 1953 "ice side, is a resilient valve disc 30 which cooperates with annular valve seat 20 to control the flow of gas through port 18. The diaphragm 28 is also provided with a disc 32 of predetermined weight which acts to bias the valve 30 in a closed position on seat 20 when the pressures acting on opposite sides of diaphragm 28 approach equality.

Communication between inlet chamber 12 and chamber 26 is provided by connecting passages 34, 36, 38, the lower portion of a blind vertical bore 40, and a passage 42. The passage 38 enters the bottom of the blind bore 40 concentrically and forms a lower seat 39 on which a ball-type pilot valve 44 movable vertically in the bore 4% is arranged to seat under certain conditions, thereby to out 01f the communication between chambers 12 and 26 just described. A disc member 46 positioned intermediately of the bore 4% is provided with a central aperture 48 which forms an upper seat arranged to he engaged by the pilot valve 44 under other conditions. The pilot valve is provided with a stem 51} which extends upwardly and exteriorly of the bare 41 through a flexible diaphragm 52. The diaphragm 52 is attached at its periphery to the cover member 22 by a suitable clamping ring 54 and the stem 50 is suitably attached to the central portion of the diaphragm in fluid pressure sealing relationship, whereby the flexible diaphragm permits vertical movement of the valve stem 519 while providing a fluid pressure tight closure of the open end of bore 40. A compression spring 56 biases the pilot valve 44 on its upper seat 48.

Under conditions wherein the pilot valve 44 is in its downward position communication between the chamber 26 and atmosphere is provided through the passage 42, the lower portion of bore 40, the aperture 48 in disc 46, the upper portion of bore 40, an orifice 58, a passage 60, a passage 62, and a bleed tube 64 to atmosphere. A threadedly adjustable valve 66 having a tapered point 68 adapted to variably enter the orifice 58 provides a variable restriction in the communication just described between chamber 26 and atmosphere.

Communication between chamber 26 and the outlet passage 14 in the valve body is also provided under conditions wherein pilot valve 44 is on its lower seat. This communication is traced from chamber 26 through passage 42, through the lower portion of bore 40, through aperture 48, through the upper portion of bore 40, through a passage 70, a passage 72, a variable orifice 74 in a disc 76, a passage 78, a bore 8%, and a passage 82 to outlet passage 14. A check valve 84 movable axially in the bore and biased in a closed position by a compression spring 86 cuts oif the just described communication between chamber 26 and outlet passage 14 when the pressure differential between these points decreases to a preselected point. The compression spring 86 bears at one end against check valve 84 and at its other end against a threadedly adjustable member 88 by means of which the closing force applied by spring 86 to the check valve 84 may be varied. A threadedly adjustable valve 91 having a tapered end 92 arranged to be variably entered into orifice 74 provides a variable restriction in the communication line between chamber 26 and outlet passage 14.

The pilot valve 44 is arranged to be moved from its biased position on upper seat 48 to its lower position on seat 39 by an electromagnetic actuator 94. The actuator 94 includes a pivoted armature 96, the free end of which overlays the exteriorly projecting upper end of pilot .valve stem 50. When the electromagnet is energized the armaturre 96 is attracted downward thereby moving pilot valve 44 to its lower seat 39.

Operation *In the drawing the electromagnetic actuator 94 is shown in a de-energized position and pilot valve 44 is biased on its upper seat 48. Under these conditions when the diaphragm valve device is connected in a fuel supply line 11 between a source of fuel supply under pressure and a burner 13 havinga" fuel metering orifice 15, supply line pressure will exist in chambers 12 and 26 and equal pressure will therefore be applied to both sides of the diaphragm 28 under static conditions. The valve 30' will consequently be closed under these conditions due to the ,weight of disc 32. Also, under closed valve conditions,

the pressure in outlet passage 14 will be atmospheric because of its communication with atmosphere through the length of supply line 11 leading to the burner and through the usual fuel metering orifice 15 at the inlet of the burner.

When it is desired to open the valve 30, the electromagnetic actuator 94 is energized by suitable circuit means, thereby effecting the movement of pilot valve 44 from its upper seat 48 to its lower seat 39. This action cuts off the communication between chamber 26 and inlet chamber 12 and establishes communication between chamber 26 and the outlet passage 14 and between chamber 26 and the bleed tube 64 through the now open passage 48. The chamber 26 is now vented to atmosphere through a first communication branch which includes the variable restriction 74 and the check valve 84 and through a second communication branch which includes the variable restriction 58. Line pressure in chamber 12 now acts on the under side of diaphragm 28 to displace it upward and to lift the valve 30 from its seat. It is to be understood that the biasing force holding check valve 84 on its seat is in all instances less than that required to hold it closed against a line pressure-atmosphere differential when stepped-opening operation of the valve is desired.

As valve 30 begins to lift from its seat the pressure in duce the restriction at orifice 74 in order to achieve the necessary discharge from chamber 26 to effect the desired rapid-opening movement of valve 30 before the pressure dilferential is lost.

The extent to which the valve 30 opens rapidly may be selectively varied in any particular installation and for any supply line pressure by varying the spring pressure applied to seating check valve 84. As the spring pressure is increased the amount of rapid valve opening movement will be decreased. This occurs because as the spring pressure is increased the rapid venting of chamber 26 to outlet passage 14 is cut off earlier. It will be noted that in this arrangement, with all other influencing factors the outlet passage 14 increases above atmospheric. This I is due in part to resistance to flow through the length of supply line extending from the device to the burner, but in considerably greater part usually to the restrictive effect of the fuel metering orifice at the burner. Continued opening of valve results in a further increase in the pressure in outlet passage 14, and when this pressure reaches a predetermined point, the check valve 84 will close thereby cutting 01f communication between chamber 26 and outlet passage 14. Chamber 26 will, however, continue to vent to atmosphere through the second branch of the venting passages and bleed tube 64'and the valve 30' will continue to move open to its full open position, but .at a considerably slower rate as predetermined by adjustment of the valve with relation to orifice 58.

When the pilot valve 44 is moved to its lower seat 38 thereby subjecting the diaphragm momentarily to the maximum pressure differential, the response of the diaphragm 28 is rapid and it will tend to overshoot the desired amount of initial rapid opening movement if venting of chamber 26 is not suitably restricted. The diaphragm and attached valve 30 will after overshooting settle back to some point as the pressure builds up in outlet passage 14, but this fluctuation is undesirable and varies in degree as between installations. Usually other factors being equal, the overshoot will be greater in installations where the run of fuel supply conduit between valve 30 and the fuel metering orifice at the burner is longer and less when the run of fuel conduit is shorter. This is so because in the instance of a long run of fuel supply conduit there is a greater space at atmospheric pressure between valve 30 and the burner metering orifice under closed valve conditions into which a greater amount of flow may discharge through outlet passage 14 before the velocity drops and back pressure builds up due to the restrictive metering orifice.

It is desirable therefore to increase the restriction at orifice 74 under conditions resulting in a relatively slow pressure build-up in outlet passage 14 in order to slow 'down the venting of chamber 26 to outlet passage 14 to reduce this overshoot. On the other hand, it will be necessary under conditions which result in a very rapid pressure build-up in passage 14 upon opening valve 30 to reconstant, the extent of the initial rapid valve opening ste will vary directly with the cross-sectional area of th burner metering orifice and inversely with line pressure. The device is therefore self-compensating, with respect to these two factors, to limit the momentary head pressure at the burner orifice to that which will supply an initial amount of fuel for initial limited combustion which is proportionate to the size of the burner orifice irrespective of supply line pressure.

The foregoing descriptionis intended to be illustrative and not limiting, the scope of the invention being set forth in the appended claims.

I claim:

1. In a diaphragm gas valve, a main valve body having a first chamber formed therein, a main fuel inlet passageway leading to said first chamber, a main fuel outlet passageway leading from said first chamber, and a main valve controlling said outlet passageway, a cover member for said valve body, a second chamber formed in said cover member, a flexible diaphragm forming a dividing Wall between said first and second chambers and being operatively connected to said main valve, means biasing said valve in a closed position, means forming a first communicating passageway connecting said first and second chambers, and means forming a second communicating passageway leading from said second chamber to atmosphere, a twoposition pilot valve operative to alternately close and open each of said communicating passageways as it is moved back and forth from its one position to the other, means forming a branch of said second communicating passageway leading from a point in said second communicating passageway between said pilot valve and atmospher' to a point in said main fuel outlet passageway downstreani from said main valve, and a normally closed check valve in said branch communicating passageway arranged to open when the pressure in said branch communicating passageway is greater than that in said main fuel outlet passageway.

2. A diaphragm valve as in claim 1 having a variable re striction in said branch communicating passageway.

3. A diaphragm valve as in claim 1 having a variable restriction in said second communicating passageway between the take-oif of said branch communicating passageway and atmosphere.

4. A diaphragm valve as in claim 1 having a variable restriction in said second communicating passageway between the take-olf of said branch communicating passageway and atmosphere and in said branch communicating passageway.

5. A diaphragm valve as in claim 1 including means for applying a variable biasing force to hold said check valve in a closed position.

References Cited in the file of this patent UNITED STATES PATENTS 1,177,864 Hodgdon Apr. 4, 1916 2,207,978 Gauger July 16, 1940 2,314,266 Beam Mar. 16, 1943 2,381,799 Berkholder Aug. 7, .1945 2,461,615 Taylor Feb. 15, 1949 2,595,171 Schaefer Apr. 29, 1952 2,638,920 Woodhull May 19, 1953

Claims (1)

1. IN A DIAPHRAGM GAS VALVE, MAIN VALVE BODY HAVING A FIRST CHAMBER FORMED THEREIN, A MAIN FUEL INLET PASSAGEWAY LEADING TO SAID FIRST CHAMBER, A MAIN FUEL OUTLET PASSAGEWAY LEADING FROM SAID FIRST CHAMBER, AND A MAIN VALVE CONTROLLING SAID OUTLET PASSAGEWAY, A COVER MEMBER FOR SAID VALVE BODY, A SECOND CHAMBER, FORMED IN SAID COVERMEMBER, A FLEXIBLE DIAPHRAGM FORMING A DIVIDING WALL BETWEEN SAID FIRST AND SECOND CHAMBERS AND BEING OPERATIVELY CONNECTED TO SAID MAIN VALVE, MEANS BIASING SAID VALVE IN A CLOSED POSITION, MEANS FORMING A FIRST COMMUNICATING PASSAGEWAY CONNECTING SAID FIRST AND SECOND CHAMBERS, AND MEANS FORMING A SECOND COMMUNICATING PASSAGEWAY LEADING FROM SAID SECOND CHAMBER TO ATMOSPHERE, A TWOPOSITION PILOT VALVE OPERATIVE TO ALTERNATELY CLOSE AND OPEN EACH OF SAID COMMUNICATING PASSAGEWAYS AS IT IS MOVED BACK AND FORTH FROM ITS ONE POSITION TO THE OTHER, MEANS FORMING A BRANCH OF SAID SECOND COMMUNICATING PASSAGEWAY LEADING FROM A POINT IN SAID SECOND COMMUNICATING PASSAGEWAY BETWEEN SAID PILOT VALVE AND ATMOSPHERE TO A POINT IN SAID MAIN FUEL OUTLET PASSAGEWAY DOWNSTREAM FROM SAID MAIN VALVE, AND A NORMALLY CLOSED CHECK VALVE IN SAID BRANCH COMMUNICATING PASSAGEWAY ARRANGED TO OPEN WHEN THE PRESSURE IN SAID BRANCH COMMUNICATING PASSAGEWAY IS GREATER THAN THAT IN SAID MAIN FUEL OUTLET PASSAGEWAY.

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