US3493001A - Hydraulic pumping system - Google Patents

Description

Feb. 3, 1970 L. BEVANDICH HYDRAULIC PUMPING SYSTEM Filed Jan. 24, 1968 I2 22 G3 PRIOR ART FIG.4

. INVENTOR LOU-IS BEVANDLCH FIG. 3

BUCKHORN, BLORE, K'LARQUIST & SPARKMAN ATTORNEYS United States Patent 3,493,001 HYDRAULIC PUMPING SYSTEM Louis Bevandich, 4155 Philomath Road, Corvallis, Oreg. 97330 Filed Jan. 24, 1968, Ser. No. 700,048 Int. Cl. E031) 11/16; F161 55/04; B67d 5/54 U.S. Cl. 13714 12 Claims ABSTRACT OF THE DISCLOSURE A hydraulic pumping system incorporating a constant speed motor driving a pump to deliver water through a delivery pipe to one or more outlets provided with shutoff valves. A hydraulic pressure storage device connected in parallel with the outlets provides for delivery of fluid at a substantially constant pressure through the use of a motor shutoif switch sensitive to tank pressure so as to activate the motor when tank pressure drops below a predetermined minimum and so as to deactivate the motor when tank pressure rises to a predetermined maximum. A check valve interposed between the tank and main delivery pipe opens in a direction to permit rapid discharge of fluid from the tank when an outlet valve is opened, and a bypass orifice bypassing the check valve permits slow filling of the tank when the pump is operating.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to hydraulic pumping systems and more particularly to a demand pressure system utilizing a motor-driven pump and a pressure-sensitive switch to operate the pump only on pressure demand.

Description of the prior art Referring to FIG. 1 of the drawing, the conventional prior art household water pumping system includes a constant displacement pump driven by a constant speed motor 12 so as to deliver water through a pipe 14 to several outlets 16 having shutoff valves 18. Downstream from the pump a hydraulic pressure accumulator in the form of a conventional pressure tank (not shown) or an expansible walled tank 20 stores water under predetermined pressure for immediate availability at the outlets when needed. A switch 22 sensitive to line pressure energizes or deenergizes the motor as required to maintain system pressure substantially constant. However the problem with such a system is that frequent recycling of the pump motor occurs when water is not being used to nearly the full capacity of the pump, such as when only one or a few of the several outlet valves is opened, because of first (a) the rapid buildup of line pressure, causing the switch to shut off the pump motor, followed by (b) the rapid dissipation of line pressure which again causes the switch to reactivate the motor. Such constant recycling is very hard on motor and pump parts, causing parts which should Wear for years to wear out Within relatively short periods of time.

The problem of rapid pump recycling is particularly serious in conventional prior art systems as shown in FIG. 1 where there is a great distance between the water tank 20 and pressure switch 22, such as in farm systems where distances of one thousand feet or more often separate the well and pump house from the tank. In such instances, when the pump shuts off, water moves back and forth in the discharge line between pressure switch 22 and the tank for a period of time. This movement causes alternate increases and decreases in pressure against pressure switch 22 in rapid succession, which in turn starts 3,493,001 Patented Feb. 3, 1970 and stops pump motor 12 at frequent intervals until lint friction finally stops the water movement.

SUMMARY OF THE INVENTION The present invention overcomes the recycling problem of prior demand pressure pumping systems througf a novel combination of features which includes (1) providing a switch for the pump motor which is sensitive tc tank pressure rather than line pressure, (2) connecting the pressure tank in parallel with the outlets, (3) providing a check valve between the main delivery pipe and the inlet to the pressure tank which prevents filling oi the tank but permits unrestricted discharge of fluid from the tank, and (4) providing a bypass orifice which bypasses the check valve to permit a slow, controlled filling of the pressure tank and thus only a slow buildup of tank pressure to the motor shutoff point when the pump is operating.

Accordingly, primary objects of the invention are to provide:

(1) A hydraulic pressure demand pumping system which eliminates the problem of constant recycling of the pump motor;

(2) A pumping system as aforesaid which utilizes for the most part conventional elements of prior systems;

(3) A pumping system as aforesaid which is simple and economical to install, operate and maintain;

(4) A system as aforesaid which requires a minimum capacity pressure storage tank;

(5) A system as aforesaid which isolates surges of water pressure resulting from water hammer after the pump shuts off from the pressure switch and thus prevents rapid starting and stopping of the pump motor following initial stopping of such motor;

(6) A bleeder-check valve for use With a system as aforesaid; and

(7) A method of converting existing hydraulic pumping systems to reduce the frequency of pump recycling.

BRIEF DESCRIPTION OF THE DRAWING The foregoing and other objects and advantages of the invention will become more apparent from the following detailed description which proceeds with reference to the accompanying drawing wherein:

FIG. 1 is a schematic view of a common prior art pumping system;

FIG. 2 is a schematic view of a pumping system in accordance with the present invention;

FIG. 2A is a schematic sectional view of the check valve unit of the system of FIG. 2, on an enlarged scale;

FIG. 3 is a schematic view of a modified pumping system in accordance with the present invention; and

FIGS. 4 and 5 are enlarged views, partly in section of bleeder-check valves suitable for use in the system of the invention.

DETAILED DESCRIPTION With reference to the drawing, FIG. 2 illustrates a pumping system of the invention including a pump 30 driven by a constant speed electric motor 32 to deliver water or other fluid from a well or sump 34 through suction line 36 into a delivery pipe 38. Main pipe or conduit 38 leads to branch supply pipes 40, 41 of, for example, a household water system having a plurality of outlets 43a, 43b, 43c and 43d provided with individual shutoff valves 45a, 45b, 45c, 45d, respectively.

Pressure accumulator means comprising tank 48 having flexible, expansible walls 49 housed within a metal shell 50 is connected to main delivery pipe 38 in parallel with outlets 43 by a short length of pipe 52. A pressure switch 54 on the tank is sensitive to pressure Within the tank and .ectrically connected to motor 32 by conductor 56 to antrol the supply of electrical current to the motor. The ressure switch activates the motor when tank pressure rops below a predetermined minimum and deenergizes 1e motor when pressure rises to a predetermined laximum.

A one-way or check valve means 58 in pipe 52 beveen main supply pipe 38 and the accumulator tank preents inflow of fluid into the tank from the supply line 'hile permitting unrestricted flow of fluid from the tank hen an outlet valve is opened. However, a bypass orifice leans 60 bypasses the check valve to permit the tank to ll slowly with fluid when pump 30 is operating. FIG. A shows check valve 58 enlarged and somewhat less :hematically than FIG. 2 and with bypass orifice 60 xtending through valve seat 62 of the valve unit. A valve all 64 prevents flow into the tank through main valve pening 66 but does not close off orifice 60.

The system of FIG. 2 may also be provided with a ressure reducing valve 68 in main supply line 38 in hose instances where the pump discharge pressure is onsiderably higher than the desire outlet pressure.

OPERATION In operation, when only one or several of the outlet alves are opened, there is an immediate supply of fluid t the outlets at the desired pressure because of the rapid ischarge of available fluid from pressure tank 48. Subequently, when pressure within the tank drops below the lredetermined minimum setting of pressure switch 54, witch 54 closes to start pump motor 32 so that water at he desired pressure will continue to be supplied to the vutlets following the unloading of the pressure tank. vIotor 32 continues to operate until pressure within the .ccumulator tank 48 builds up to the predetermined maxi- Jurn shutoff setting of the pressure switch. Even if only vne or a few outlet valves are opened, motor 32 will p rate for a considerable length of time because orifice 60 sized to prevent a rapid buildup of fluid pressure within he tank following its initial discharge. Ideally, orifice 60 hould be sized so that the tank will not reach shutoff IICSSHIG even with only one outlet valve open until such 'alve is reclosed, whereby the motor runs continuously luring the drawing of any appreciable quantity of water rom the system.

EXAMPLE Assuming a desired outlet pressure of 50 p.s.i., the ump or pressure reducing valve would be selected acordingly. A suitable pressure accumulator tank might be Jacuzzi Hydrocel brand tank of three or five gallon apacity capable of withstanding 75 p.s.i. hydraulic presure. Under these circumstances the pressure regulator vould be set to shut off the pump motor when the presure within the tank reaches 40 to 65 p.s.i. The minimum ize of orifice under these conditions should be approximately one-sixteenth of an inch. It has been found that lnder these conditions and using a pump with a discharge ressure of 55 p.s.i. with only one or a few outlet valves pen, water will enter the pressure storage device at a ate of about eight-tenths of a gallon per minute.

FIG. 3 EMBODIMENT FIG. 3 illustrates the conversion of a conventional in- .talled water system having the usual rigid-walled presure tank 70 to a system in accordance with the present nvention. The tank has an air space 72 exerting pressure m the surface 74 of water within the tank to place the .ystem under pressure. The conversion is accomplished vy capping the normal outlet 76 of the tank, bypassing he tank with the main delivery pipe '78, and moving the iressure-sensitive control switch 80 from the main deivery pipe as shown in FIG. 1 to the tank as shown in FIG. 3 so that it acts in response to tank pressure rather han line pressure. Then a bleed-check valve 82 with bypass orifice 84 is installed in the inlet pipe 86 to the tank so that the tank will unload rapidly but fill slowly. Thus the pressure tank will be connected in parallel with outlets 88, and the system will operate in the same manner as previously described with reference to the system of FIG. 2.

FIGS. 4 and 5 illustrate practical embodiments of bleed-check valves suitable for the above-described systems of FIGS. 2 and 3. In the embodiment of FIG. 4 bypass bleed orifice 90 passes through valve disc 92, which seats against valve seat 94 to prevent all but a minimal flow into the tank. The tubular valve body 96 may be threaded at its opposite ends (not shown) to provide for ready coupling to the accumulator tank and other pipe elements.

In the valve of FIG. 5, the bypass bleed orifice 98 passes through an annular valve seat 99. A ball closure 10%) of the valve is made of rubber or other nonmetallic material to prevent excessive noise in the system upon closure of the valve.

In addition to being an important element in preventing rapid recycling, the bypass bleed orifice in the check valve means of the system isolates the accumulator tank and pressure switch from the effects of water surge and water hammer in systems particularly subject to such conditions.

Having illustrated two embodiments of my invention, it should be apparent to those skilled in the art that the same permits of modification in arrangement and detail.

Iclaim:

1. In a hydraulic pumping system:

pump means,

conduit means extending downstream from a discharge side of said pump means to an outlet, shutoff valve means at said outlet, hydraulic pressure accumulator means connected in said conduit means in parallel with said outlet,

valve means in said conduit means between said pump means and said accumlator means and in parallel with said outlet,

said valve means including means permitting rapid fiow from said accumulator means and slow flow into said accumulator means to provide an immediate supply of fluid at predetermined pressure at said outlet when said shutoff valve means is opened and to provide a slow buildup of pressure in said accumulator means while said shutoff valve remains open and during the operation of said pump means,

and pressure-sensitive pump-operating means responsive to predetermined pressures in said accumulator means for activating and deactivating said pump means. 2. A system according to claim 1 wherein said pump means comprises a pump driven by a constant speed motor and including pressure sensitive means responsive to a predetermined low pressure in said accumulator means for activating said motor and responsive to a predetermined high pressure in said accumulator means for deactivating said motor.

3. A system according to claim 1 wherein said outlet means comprises a plurality of outlets, said shutoff valve means includes a separate shutoff valve for each outlet and said valve means includes orifice means sized to provide a slow buildup of fluid pressure within said accumulator means when only one of said shutoff valves is open.

4. A system according to claim 1 wherein said valve means includes bypass orifice means integrated within a common valve body.

5. A system according to claim 1 wherein said accumulator means comprises a closed tank having walls of flexible expansible material.

6. A system according to claim 1 wherein said accumulator means comprises a closed tank having rigid walls and an air space within an upper portion of said tank.

7. A system according to claim 1 including high pressure regulating means in said conduit means between said pump means and said valve means for controlling the maximum pressure at said shutoff valve means and said accumulator means.

8. In a hydraulic pressure demand pumping system including a motor-driven pump for delivering fluid to a valve controlled outlet means in a delivery pipe, and a pressure accumulator tank having an inlet connected to said pipe, a valve means for controlling the inflow and outflow of fluid from said tank comprising:

said valve means including valve closure means preventing the flow of fluid into said tank and permitting the unrestricted outflow of fluid from said tank,

bypass orifice means bypassing said closure means so as to permit a controlled, restricted flow of fluid into said tank at a rate substantially less than the rate of said outflow from said tank,

and pressure sensitive switch means sensitive to pressure in said tank for activating and deactivating said pump.

9. A valve means according to claim 8 wherein said closure means includes a stationary valve seat defining a valve opening and a movable valve closure element engageable with said seat for closing said opening, said orifice means passing through said closure element.

10. A valve means according to claim 8 wherein said closure means includes a stationary valve seat defining a valve opening and a movable valve closure element engageable with said seat for closing said opening, said orifice means passing through said seat.

11. A valve means according to claim 10 wherein said closure element is composed of a rubber or other nonmetallic material.

12. A method of preventing rapid recycling of a pump motor in a demand pressure hydraulic pumping system including a motor-driven pump which delivers water from a source to one or more outlets through a closed conduit,

said pump having a flow capacity greater than that of one of said outlets,

said method comprising the steps:

accumulating a supply of hydraulic fluid at approximately system pressure adjacent to said conduit,

upon the opening of one of said outlets, discharging fluid rapidly from said supply into said conduit to provide fluid immediately at said one outlet at system pressure,

sensing the pressure of said supply and activating the pump motor to operate said pump when the pressure of said supply reaches a predetermined minimum to pump fluid from said source to said outlet,

slowly rebuilding said supply by diverting a small restricted portion of the flow from said pump and conduit to said supply while continuing to sense the pressure of said supply,

and continuing the operation of the pump until the pressure of the supply reaches a predetermined maximum, then deactivating the motor to stop the operation of said pump.

References Cited UNITED STATES PATENTS ROBERT G. NILSON, Primary Examiner U.S. Cl. X.R.

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