GB2057635A - Control valve for a water pressure booster system - Google Patents

Abstract

A control valve comprising, a housing having an inlet passage 40 and an outlet passage 48, a valve member 36 slidably contained within said housing having a central shaft 70 with a throttle valve portion 94 on a first end of said central shaft and a balance piston 72 on a second end, said valve member located such that said inlet passage is intermediate said throttle valve and said balance piston, means 38 for establishing a regulated pressure acting on said balance piston such that the movement of the slidable valve member is controlled by the pressure differential between the regulated pressure and a pressure at the outlet passage, and check valve means 98 located in said throttle valve portion and controlling fluid flow between said inlet passage and said outlet passage when said throttle valve portion is closed, said check valve means allowing fluid flow when said inlet pressure is greater than said outlet pressure and preventing fluid flow when the outlet pressure exceeds the inlet pressure. <IMAGE>

Description

SPECIFICATION Control valve for a water pressure booster system Technical Field of the Invention This invention relates to a control valve suitable for use in a water pressure booster system.

Background Art Water pressure booster systems are well known, and generally serve to maintain adequate water pressure in tall buildings or in smaller buildings located in areas which have inadequate or antiquated municipal water supply systems.

These systems operate to "boost" the water pressure inside an individual building when the pressure drops to a point beiow which it becomes impossible to achieve normal water usage.

Typical prior art booster systems have included a motor driven pump connected to a water supply source, such as a well or municipal supply system, a control valve to regulate a pressure actuated switch to switch the pump motor on and off in dependence of the buildings water pressure. The aforedescribed system meets the basic requirements of a booster system, however, it results in frequent on-off cycling of the motor and pump, since-any opening of a faucet would reduce the pressure in the system enough to turn on the pump.

To alleviate this problem, it is known to provide an accumulator tank in the system. This tank provides water to the system for relatively small amounts drawn off by opening the service faucets without the necessity of turning on the pump and motor. However, the inclusion of such a tank in the system renders the function of the control valve more difficult, since it must allow the motor and pump to continue to run after the service faucet has been shut off to replace the water drawn from the accumulator tank.

The prior art booster systems have generally utilized a diaphragm actuated valve to regulate the pressure in the system and to control the refilling of the accumulator tank. Some of the prior art use a pilot pressure in conjunction with the diaphragm to control the position of the valve, while others use biasing means, such as a spring or pneumatic pressure.

The diaphragm in such control valves is subject to failure both through rupture and through ineffective sealing about its periphery. Also, in those systems which use biasing means along with the diaphragm, the biasing means must exert sufficient force on the valve member to overcome any frictional forces to insure closing of the valve.

This obviously increases the force necessary to open the valve and, consequently, increases the pressure drop through the control valve.

An object of the present invention to provide a control valve which regulates the pressure of water delivered within a narrow band and accomplishes such with low loss of pressure at high flow rates.

It is a further object to provide such a control valve which is capable of overcoming large frictional resistances as may be caused by foreign matter entering the valve or by accumulation of fouling within the valve.

Disclosure of the Invention According to one aspect of the present invention a control valve comprises a housing having an inlet passage and outlet passage, a valve member slidably contained within said housing having a central shaft with a throttle valve portion on a first end of said central shaft and a balance piston on a second end, said valve member located such that said inlet passage is intermediate said throttle valve and said balance piston, means for establishing a regulated pressure acting on said balance piston such that the movement of the slidable valve member is controlled by the pressure differential between the regulated pressure and a pressure at the outlet passage, and check valve means located in said throttle valve portion and controlling fluid flow between said inlet passage and said outlet passage when said throttle valve portion is closed, said check valve means allowing fluid flow when said inlet pressure is greater than said outlet pressure and preventing fluid flow when the outlet pressure exceeds the inlet pressure.

According to another aspect of the invention a control valve comprises a housing having an inlet passage and an outlet passage, a valve member contained within said housing without biasing means so as to be freely slidable therein, said valve member having a central shaft with a throttle valve portion on a first end of said central shaft and a balance piston on a second end, said valve member located such that said inlet passage is intermediate said throttle valve and said balance piston, means for establishing a regulated pressure acting on said balance piston such that the movement of the slidable valve member is controlled by the pressure differential between the regulated pressure and a pressure at the outlet passage, and flow control/check valve means located in said throttle valve portion and controlling fluid flow between said inlet passage and said outlet passage when said throttle valve portion is closed, asid flow/check valve means allowing fluid flow when said inlet pressure is greater than said outlet pressure and preventing fluid flow when the outlet pressure exceeds the inlet pressure.

Preferably, the balance piston has an orifice or channel therethrough to allow passage of fluid from a first, inlet side to a second side of said balance piston.

The control valve may have pressure regulating means connected to said housing to regulate the pressure acting on said second side of said balance piston.

Conveniently, the throttle valve portion may have an outer surface in the shape of a compound truncated cone such that the amount of fluid throttling is inversely proportional to the distance between said throttling valve and its seat.

Alternatively, the throttle valve portion may have an outer surface in the shape of a truncated paraboloid such that the amount of fluid throttling is inversely proportional to the distance between said throttling valve and its seat.

An embodiment of the invention incorporated in a water pressure booster system of the kind described and claimed in co-pending Patent Application No. 40178/78 will now be described, by way of exampie, with reference to the accompanying drawings.

Brief Description of the Drawings Figure 1 is a schematic representation of a water pressure booster system incorporating a control valve according to the invention.

Figure 2 is a cross-sectional view of the control valve shown in Figure 1.

Figure 3 is an enlarged cross-sectional view of an alternative embodiment of the throttle valve shown in Figure 2.

Figures 4 to 6 are sequential views showing, in cross-section, the operational position of the valve shown in Figure 2 during operation of the booster system of Figure 1.

Figure 7 is a graph of the operational characteristics of the water pressure booster system of Figure 1.

Best Mode for Carrying Out the Invention The water pressure booster system incorporating a control valve according to the invention is shown diagrammatically in Figure 1 and comprises a water pump 10 driven by electric motor 12, a control valve assembly 14, an accumulator tank 16, and a pressure actuated switch 18. A pump 10, which may be any type of pump suitable for a specific application (such as Gould shallow well pump Model JL07NS), has its inlet connected to a source of water which may be a well or municipal water supply system, via conduit 20. The outlet of pump 10 is connected to control valve assembly 14 via conduit 22.Control valve assembly 1 4 has a through passage connected on one side to accumulator 1 6 and pressure switch 18 by conduits 26 and 24 respectively, and on the other side to the building piping distribution system shown diagrammatically by conduit 28 and service outlet faucet 30. Figure 1 is only a diagrammatic representation and any number of faucets and outlets may be provided throughout the building.

Accumulator 1 6 and pressure switch 1 8 are standard, commercially available items.

Accumulator 16 may be Well-X-Trol Model WX202 made by Amtrol Inc., while the pressure switch may be that incorporated in the aforementioned Gould pump, Model JL07NS.

Obviously, any other items having similar functional characteristics may be used without exceeding the scope of this invention.

Motor 12 is connected to a source of electrical power via power supply cable 32 through pressure switch 1 8. If the location of the pressure booster system so permits electric motor 12 may be replaced by an internal combustion engine, or any other power source to drive pump 10.

Control valve assembly 14 is shown in detail in Figure 2 and comprises a housing 34, slidable valve member assembly 36 and back pressure regulator assembly 38. Housing 34 has inlet passage 40 connected to the outlet of pump 10 via standard threaded connections and conduit 22. A similar passage 42 is provided for connection to accumulator tank 1 6. Another passage 46 is provided, coaxially aligned with passage 42, to allow connection of control valve assembly 14 to the service outlet faucets 30. This passage extends perpendicularly from the plane of Figure 2 and is shown schematically in Figure 1.

Housing 34 also has threaded passages 48 and 50 for connection to a pressure gauge, and to the inlet conduit 20, respectively. Access plug 52 is threaded into the top of housing 34 to facilitate the installation and removal of valve member assembly 36. Access plug 52 has annular depending skirt 54 extending into housing 34 to limit the upward movement of valve member assembly 36. Passage 56 may be provided in access plug 52 to connect pressure switch 1 8 with a source of line pressure.

The lower portion of housing 34 is connected to back pressure regulator assembly 38. Regulator assembly 38 may be attached directly to housing 34, as shown in Figure 2, or may be separate therefrom and be connected via a conduit.

Regulator assembly 38 may also be a standard, off-the-shelf item such as Cash - Acme Model A31 R. Generally, regulator assembly 38 comprises a housing 58, which may threadingly engaged with housing 34; a diaphragm 60 which extends across and seals-the open end of housing 58; screw 62 threadingly engaging housing 58; and spring 64 which extends between screw 62 and diaphragm 60, normally biasing sealing member 66, attached to diaphragm 60, against the bottom of housing 34 thereby sealing off passage 68. As can be seen, passage 68 communicates with aforedescribed passage 50.

Valve member assembly 36 has central shaft 70 with balance piston 72 on its lower end, and throttle valve 74 on its upper end. Balance piston 72 has peripheral sealing means 76 to effect a seal between it and the inner surface 78 of housing 34. Orifice 80 is provided through balance piston 72 to allow fluid communication between central chamber 82 and lower chamber 84 within housing 34. Orifice 80 has a cross-sectional area of approximately .001 to .005 sq. in. Lower chamber 84 also communicates with back pressure regulator assembly 38 via passage 86.

Throttle valve 74 has a plurality of longitudinal valve guides 88 circumferentially displaced about its periphery. The guides 88 keep the longitudinal centerline of valve member assembly 36 coincident with the centerline of housing 34 during upward and downard movement of the valve member assembly.

The outer surface of throttle valve 74 is shaped such that it throttles the flow of fluid between central chamber 82 and upper chamber 90. This may be achieved by forming the outer surface in the shape of truncated cones having increasing side angles, as shown in Figure 2, or by forming the outer surface in the shape of a truncated paraboloid, as shown in Figure 3. In either case, the rate of flow between central chamber 82 and upper chamber 90 will increase as valve member assembly 36 moves upwardly.

When valve member assembly 36 is in its lowermost position, as shown in Figure 2, fluid communication between central chamber 82 and upper chamber 90 is normally prevented by sealing member 92, attached to valve member assembly 36, bearing against valve seat 94 defined by the upper surface .of cylindrical inner projection 96 of housing 34.

The upper portion of valve member assembly 36 also contains flow control/check valve 98.

Valve 98 is free to move between lower valve seat 100 and upper valve seat 102, depending upon the pressure differential between central chamber 82 and upper chamber 90. When the pressure in upper chamber 90 is greater than that in central chamber 82, flow control/check valve 98 will be pushed downwardly onto seat 100. If the pressure in central chamber 82 exceeds that in upper chamber 90, valve 98 will be pushed upwardly and engage valve seat 1 02. Valve seat 102 has at least one, and preferably a plurality of radial grooves emanating from the opening of passage 104 and extending to the outer circumference of seat 1 02 such that it allows passage of fluid even when check valve 98 engages seat 102.If two grooves are used, a width of .080 to .200 and a depth of .040 to .080 have been found sufficient to provide a flow rate of approximately 0.5 to 1.0 GPM from the pump into the system through this valve.

The flow control/check valve 98 is made of resilient material having a durometer of 40 to 70.

Fluid will pass from central chamber 82, through passage 106, around the periphery of check valve 98, through the radial grooves, and into passage 104. The purpose of allowing passage of fluid past check valve 98 when in this position will be described hereinafter.

When check valve 98 engages valve seat 100, flow past the check valve between upper chamber 90 and central chamber 82 is prevented.

Screen 108 may be provided between the throttle valve portion and balance piston 72 to prevent dirt and other foreign matter from clogging or blocking the various passages in valve member assembly 36.

The operation of the system and the control valve will be described with particular reference to Figure 4-6. As starting conditions, it will be assumed that service outlet faucet 30 is closed, motor 12 and pump 10 are off, accumulator 16 is filled to capacity, and that valve member assembly 36 and check valve 98 are in the positions shown in Figure 4. Once service outlet faucet 30 is opened, the requisite water is initially supplied from the water in the piping system and that in accumulator 16. If the demand is sufficiently great, the pressure in conduits 24, 26 and 28 drops to the set point of pressure switch 1 8. At this point, pressure switch 1 8 completes the circuit and turns on motor 12 and pump 10. The output from pump 10 enters control valve assembly 14 through passage 40.The diameters of balance piston 72 and throttle valve 74 are equal, therefore the pressure of fluid entering passage 40 does not move valve member assembly 36 in either direction.

The fluid passes through orifice 80 into lower chamber 84 and passage 86. It is prevented from proceeding further since sealing member 66 is blocking passage 68. Thus, fluid pressure builds up on the lower side of balance piston 72. This pressure builds up to a predetermined level, whereupon the force acting on diaphragm 60 overcomes the force exerted thereon by spring 64. Sealing member 66 opens passage 68 allowing fluid to pass therethrough and back into pump inlet conduit 20. Thus, pressure regulator assembly 38 controls the pressure level acting on the lower side of balance piston piston 74. This pressure can be manually adjusted by turning screw 62 and is typically adjusted to approximately midway between the cut in and cut out pressure of pressure switch 1 8 (i.e.

40-50 psig).

Once this pilot pressure acting on the lower side of balance piston 72 exceeds the system pressure present in upper chamber 90, valve member assembly 36 will move upwardly, unseating sealing member 92. Flow control/check valve 98 will also move upwardly as shown in Figure 5, when pressure in central chamber 82 exceeds the system pressure. Fluid passing between central chamber 82 and upper chamber 90 is throttled by throttle valve 74 as previously described. The position of throttle valve 74 with respect to seat 94 and the consequent amount of throttling is determined by the pressure differential between upper chamber 90 and lower chamber 84.

The valve member assembly 36 continues to control the flow of fluid into the system as long as service outlet faucet 30 is open. Once faucet 30 is closed, the pressure in the piping system will gradually build up to a point where it exceeds the pilot pressure acting on balance piston 72. At this point, valve member assembly 3.6 will move downwardly. It should be noted that the rate of increase of the pressure in the piping system and accumulator will diminish as throttle valve 74 approaches seat 94 due to its increased throttling of the fluid flow into upper chamber 90. This permits the motor 12 and pump 10 to run for longer periods of time and prevents the deleterious on-off cycling of the motor and pump.

The pressure in upper chamber 90 (and in the piping system) will gradually increase to a point where it will close throttle valve 74 completely, as shown in Figure 6. At this point, the pressure in central chamber 82 is greater than that in upper chamber 90, thereby keeping flow control/check valve 98 in its upper position wherein it allows fluid flow, as previously described.

The fluid flowing past check valve 98 and into upper chamber 90 serves to refill accumulator 1 6.

The resiliency of flowcontrol/check valve 98 serves to maintain the filling time of the accumulator relatively constant, regardless of the differential between the pump pressure and system pressure. The greater the pressure differential the more the valve 98 will deform into the aforementioned radial grooves so as to prevent increased flow therethrough caused by the greater pressure differential.

Once the accumulator 1 6 is refilled the pressure in the piping systems reaches the cut-off level of pressure switch 18 which turns off motor 12 and pump 10. Check valve 98 then contacts seat 100 to prevent backflow from upper chamber 90 into central chamber 82. The system is then in the position of Figure 4 and ready to begin another cycle.

Results of a test of a typical valve are shown in Figure 7. For this test the pump cut in was set at 40 psig and pump cut-off was set at 60 psig. The pilot pressure varies with pump pressure and ranged from 40 to 50 psig. Pump discharge was 70-100 psig at low flow and 40-70 psig at high flow. Typical flows through throttle valve 74 ranged from 1-20 GPM, while flows through check valve 98 and orifice 80 were 0.5-1.0 GPM.

Claims (12)

1. A control valve comprising, a housing having an inlet passage and an outlet passage, a valve member slidably contained-within said housing having a central shaft with a throttle valve portion on a first end of said central shaft and a balance piston on a second end, said valve member located such that said inlet passage is intermediate said throttle valve and said balance piston, means for establishing a regulated pressure acting on said balance piston such that the movement of the slidable valve member is controlled by the pressure differential between the regulated pressure and a pressure at the outlet passage, and check valve means located in said throttle valve portion and controlling fluid flow between said inlet passage and said outlet passage when said throttle valve portion is closed, said check valve means allowing fluid flow when said inlet pressure is greater than said outlet pressure and preventing fluid flow when the outlet pressure exceeds the inlet pressure.

2. A control valve as claimed in Claim 1, wherein the balance piston has an orifice or channel therethrough to allow passage of fluid from a first, inlet side to a second side of said balance piston.

3. A control valve as claimed in Claim 1 or Claim 2, comprising pressure regulating means connected to said housing to regulate the pressure acting on said second side of said balance piston.

4. A control valve as claimed in any preceding claim, wherein the throttle valve portion has an outer surface in the shape of a compound truncated cone such that the amount of fluid throttling is inversely proportional to the distance between said throttling valve and its seat.

5. A control valve as claimed in any one of Claims 1 to 3, wherein the throttle valve portion has an outer surface in the shape of a truncated paraboloid such that the amount of fluid throttling is inversely proportional to the distance between said throttling valve and its seat.

6. A control valve comprising, a housing having an inlet passage and an outlet passage, a valve member contained within said housing without biasing means so as to be freely slidable therein, said valve member having a central shaft with a throttle valve portion on a first end of said central shaft and a balance piston on a second end, said valve member located such that said inlet passage is intermediate said throttle valve and said balance piston, means for establishing a regulated pressure acting on said balance piston such that the movement of the slidable valve member is controlled by the pressure differential between the regulated pressure and a pressure at the outlet passage, and flow control/check valve means located in said throttle valve portion and controlling fluid flow between said inlet passage and said outlet passage when said throttle valve portion is closed, said flow/check valve means allowing fluid flow when said inlet pressure is greater than said outlet pressure and preventing fluid flow when the outlet pressure exceeds the inlet pressure.

7. A control valve as claimed in Claim 6, wherein the balance piston has an orifice or channel therethrough to allow passage of fluid from a first, inlet side to a second side of said balance piston.

8. A control valve as claimed in Claim 6 or Claim 7, wherein the throttle valve portion has an outer surface in the shape of a compound truncated cone such that the amount of fluid throttling is inversely proportional to the distance between said throttling valve and its seat.

9. A control valve as claimed in Claim 6 or Claim 7, wherein the throttle valve portion has an outer surface in the shape of a truncated parabolid such that the amount of fluid throttling is inversely proportional to the distance between said throttling valve and its seat.

10. A control valve as claimed in any one of claims 6 to 9, comprising pressure regulating means connected to said housing to regulate the pressure acting on said second side of said balance piston.

11. A control valve substantially as hereinbefore described with reference to Figure 2 and Figures 4 to 6 of the accompanying drawings.

12. A control valve substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.