US2240607A - Fluid control system - Google Patents

Description

May 6, 1941. c. M. BUCK FLUID CONTROL SYSTEM Filed Jan. 6, 1938 5T0 RAGE TAN K SOURCE OF POWER SOURCE OF POWER ATTORNEY Patented May 6, 1941 v UNITED STATES. PATENT OFFICE FLUID CONTROL SYSTEM Application January 6, 1938, Serial No. 183,645

' 4 Claims. (61. 103-25) The present invention relates generally to control systems and more particularly to systems controlling pumps or other fluid forcing devices.

In fluid pumping systems such as used for community water service,'water is pumped from a well or other source of water to' a standpipe or storage tank which in many cases may be a con siderable distance from the pump. In systems of this type, it has become common to utilize the pipe line leading from the pump to the storage tank as a part of the distributing system in order to avoid the expense of running a. separate line between the pump and tank. Also, in systems of this type, it has become common to control the pump in accordance with" the water level in the storage tank, the pump being started when the water level falls to a predetermined low level, and being placed out of operation when the level is raised to a predetermined higher level.

In systems of this general class, difficulty has been experienced due to surges in pressure caused by starting and stopping of the pump. When the pump starts, it attempts suddenly to place the large column of water between the pump and the tank into motion. Due to the large inertia of this water column, the water does not immediately begin to move, but instead, the pressure rises or surges to a much higher value than normally exists within the system. Also, when the pump stops, the inertia of the water then in motion tends to keep it in motion. Due to the fact that water is no longer being supplied to the system by the pump, the pressure in the system momentarily drops to a value below normal when the pump is placed out of operation.

These surges in water pressure within the entire distribution system are of course objectionable, as it causes spurts of water through open faucets when the pump starts and causes momentary stopping or diminishing of the water supply when the pump stops. In addition, these surges in pressure have an undesirable effect upon the pump starts, while slowly opening'after the which pump has started, and to be slowly closed before the pump is stopped. By this arrangement, whenever the pump is stopped or started, the valve is closed, thus preventing the sudden starting or stopping of the pump from influencing the pressure in the distribution system. Due to the slow opening and closing movement of this valve, the water is gradually placed into or out of motion, and'consequently, surges in pressure in the system are eliminated. This forms another object of my invention. 1

A further object of my invention is the provision of an arrangement of the type mentioned above which will act upon failure of power to the and are of utility in gas or air pumping systems.

Also, while the inventionis described as applied to a control system in which a single pump is stopped or started, certain features of the invention are equally applicable to systems utilizing a plurality of pumps operated in sequence, or in systems wherein the speed or output of the pump is graduatingly controlled instead of being stopped and'started. Other objects will be apparent from the following description and the appended claims.

For a full disclosure of my invention, reference is made to the following detailed description and to the accompanying drawing, the single figure of illustrates diagrammatically one form which my invention may take.

Referring to the drawing, reference character I indicates a pump which may be of the centrifugal or turbine type, this pump being connected to an intake line 2 leading from a well or other water supply source 3. The discharge connection of the pump is connected by a pipe 4 to a valve 5, the discharge of this valve being connected to a r discharge main 6 leading to a storage tank 'i.

Interposed in the discharge main -6 may be a check valve 8 and a stop valve 9.

The pump l is driven by means of a motor it, this motor being controlled by means of a magnetic starter generally indicated as l I. Referring to the magnetic starter I I, this device may consist of a coil 12 cooperating with an armature (not shown) for positioning switch arms l3, l4, l5, and it. These switch arms cooperate with contacts II, i8, i9, and 20, respectively. When the starter coil I2 is energized, the armature is pulled to the right thus causing the switch arms l3, l4, l5, and II to engage their respective contacts l1, l8, l3, and 20. Upon deenergization oi the coil l2 the switch arms l3, i4, i5, and I6 are pulled to the leit away from their respective contacts under the action of gravity or springs (not-shown) The contacts II, II, and I! are connected to the three- phase line wires 21, 22, and 23, respectively. The switch arms I 3, l4, and i are connected to wires 24, 25, and 26, respectively, which lead to the pump motor I 0. From the description thus far, it should be apparent that when the relay coil I2 is energized, the power circuit to the pump motor II will be completed and the pump I will be placed into operation. When the coil I2 is deenergized, however, the pump will be placed out of operation.

The magnetic starter II is controlled in part by means or a storage tank level controller generally indicated as 30. This controller consists of a low limit bellows 3| and a high limit bellows 32, these bellows being connected by pipes 33 and 34 to the supply main 5, a needle valve 35 being provided for preventing small surges in pressure within the main 3 from influencing the bellows 8| and 32. The bellows 3| cooperates with a pivoted switch carrier 35 which carries a mercury switch 31. The bellows is adjusted by means of a biasing spring (not shown) or other adjusting means so as to cause the mercury switch 31 to remain open when the pressure within the bellows indicates that the water level in the storage tank I is above a predetermined value. When the water level falls to this predetermined value, the bellows II will contract sufllciently to permit tilting of the mercury switch 31 to closed position. The bellows 32 actu'ates a mercury switch 38. This bellows is so adjusted as to permit the mercury switch 33 to be tilted to closed position, as shown, whenever the pressure within the bellows indicates that the water level in the storage tank is below a predetermined high level. When the pressure within the bellows 32 rises to a value indicating that the water level has reached the desired high'limit, the mercury switch 38 will be tilted to open position. The controller 30 also includes a time delay device 40, this device consisting of a bimetallic element 4| which is subjected to the influence of a heating element 42. The bimetallic element 4| is fixedly secured at its upper end, and at its lower end carries a mercury switch 43. When the heating element 42 is deenergized, the bimetallic element assumes the position shown, in which the mercury switch 43 is open. When the heating element 42 is energized, however, the resulting increase in temperature oi the bimetallic element 4| will cause this element to warp in a direction for tilting the mercury switch 43 to closed position.

' The valve 5 is adapted to be actuated by means of a reversible electric motor 45. This motor includes an actuating arm 46 which is connected by a pitman 41 to the stem 48 of the valve 5. The motor 45 may be of a type well-known in the art, .his motor being provided with a three-wire control circuit and being adapted to assume one extreme position when the common wire of the control circuit is connected to one of the control wires, and to assume its other extreme position when the common wire is connected to the other control wire. 7

The motor 45 is also arranged to actuate a pivoted mercury switch carrier 49 which carries a mercury switch 50. As shown, the actuating arm 46 of the motor is arranged to engage the switch carrier 49 and tilt the mercury switch ll to closed position whenever the valve -5 is partly or completely open. When the valve 5 is closed, however, the actuating arm 46 of the motor 45 will permit tilting of the switch 50 to open position as shown. The purpose of this arrangement will become apparent as this description proceeds. It will be understood that the motor actuated switch 50 may be actuated in any desired manner by the motor and that the arrangement shown is for illustrative purposes only.

The motor 45 is arranged to be controlled by means of a relay indicated as 5|. This relay consists of a relay coil 52 which is adapted to control the position of a switch arm 53 which cooperates with opposed contacts 54 and 55. The switch arm 53 is connected to the common terminal 55 of the motor 45 by means of a wire 51, and the contacts 54 and 55 are connected to the other control terminals of this motor by means of wires 55 and 59, respectively. When the relay coil 52 is deenergized the switch arm 53 will be caused to engage the contact 55 due to the action of gravity or springs (not shown). This will cause the motor 45 to assume a position in which the valve 5 is closed and the mercury switch is open as shown. When the relay coil 52 is energized, however, the switch arm 53 will be brought into engagement with the contact 54, this causing the motor 45 to open the valve 5 and to close the mercury switch 50. The motor 45 is preferably of a type which is very slow acting. For instance, this motor may be geared down to such an extent as to require a period ,of two minutes for opening the valve 5 and a like period for closing this valve.

Operation With the parts in the position shown, the water level in the storage tank 1 is above the predetermined low value as indicated by the mercury I switch 31 being open and is below the predetermined high value as indicated by mercury switch 38 being closed. Due to the fact that the mercury switch 31 controls the heating element 42, the heating element 42 at this time is deenerglzed and consequently the mercury switch 43 is open. For these positions 01' the various mercury switches the starter coil I2 is deenergized and consequently the switch arms l4, l5, and ii are disengaged from their respective contacts. Hence the pump motor in is deenergized. At this time, the coil 52 of the relay 5| is deenergized, which causes engagement of the switch arm 53 with contact 55 and this has caused the motor 45 to close the valve 5 and open the mercury switch 50.

When the water level within the storage tank 1 falls to the predetermined low level, the bellows 3| will collapse sufllciently to close the mercury switch 31. This will energize the heating element 42 by a circuit as follows: line wire 22, wire 50, mercury switch 31, wire 5i, heating element 42 and wire 62 to line wire 23. This energizatlon oi the heating element 42 will cause heating of the bimetallic element 4| thereby after a predetermined interval causing closing or the mercury switch 43. This will result in energizing the starter coil i2 as follows: line wire 22, wire 54, mercury switch 43, wire 65, wire 65, starter coil l2 and wire 61 to line wire 23. This will cause engagement of the switch arms l3, l4, l5, and I5 with their respective contacts thereby energizing the pump motor ill for placing the pump I into operation. At this time, the valve 5 is closed and consequently there is no surge in pressure within the discharge main due to the pump starting. Due to power being supplied to the pump motor III, the relay coil 52 will now be energized as follows: wire26, wire 58, relay coil 52, wire 59, mercury switch 38 and wire to the wire 25. This will cause engagement of the switch arm 53 with ,the contact 54 thereby energizing the motor 45 for opening the valve 5. The motor 45 will now begin to open the valve 5 slowly, this allowing the water within the discharge main 5 to be slowly placedinto motion. Due to the slow opening movement of the valve 5 there will be no surge in pressure caused by the placing of the water within the main 6 into motion.

As the valve 5 begins opening, the mercury switch 50 will be tilted to closed position. This will establish a maintaining circuit for the starter coil l2 as follows: line wire 22, wire 54, wire ll, contact 20, switch armlG, wire 12, mercury switch 50, wire 13, wire 66,.starter coil l2, and wire 51 to line wire 23. Due to the establishment of this maintaining circuit, the pump motor Ill will remain energized even after the mercury switch 31 has opened, thus allowing cooling of the heater 40 and opening of the mercury switch 43. Consequently, when the mercury switch 31 opens due to the increased pressure within the main 8, which is caused by the friction to the moving column of water, the pump will remain in operation. It will be noted that the mercury switch 31 must remain closed for a considerable period before the mercury switch 43 of the timer 40 will close. This action will prevent the pump from being started due to momentary drops in-pressure within the distributing system as may be caused bytemporary draw-oiTs of water from the system. This timer 40 also has other functions which will become apparent.

It will be noted that the energizing circuit for the relay coil 52 is through the mercury switch 38 of the controller 30. Consequently, when the water pressure increases to a point indicating that the maximum level in the storage tank has been reached, the mercury switch 38 will open, thereby deenergizing the relay coil 52. This will cause the switch arm 53 to engage the contact 55 for energizing the motor 45 for causing it to drive the valve 5 towards closed position. Due to the slow movement of the valve 5 under the action of motor 45, the flow of water through the discharge main 6 will be gradually restricted and finally stopped without the occurrence of any surge. When the valve 5 reaches closed po sition, the mercury switch 50 will open as shown, I and this willbreak the maintaining circuit for the starter coil l2 thereby allowing the switch arms I3, l4, l5, and I5 to disengage their respec-. tive contacts and deenergize the pump motor l0.

When the pump motor I0 is deenergized the pump I may be caused to spin backwardly due to the column of water in the intake pipe 2. At this time, however, the supply of power to the pump motor ID will be prevented by the timer 40. In other words, even if there should be a demand for water immediately following stopping of the pump, the pump will be prevented om starting for a timed period which will be of suflicient duration to permit the back-spin of the pump to stop. The timer 40, therefore, in addition to preventing starting of the pump due to momentary draw-offs, also provides for backspin protection of the pump motor. In other words, the pump motor Ill cannot be energized during the period that it is spinning backwardly.

In the event that a power failure should occur during an operating period of the pump, the starter coil l2 will become deenergized thereby allowing the switch arms I3, [4, l5, and IE to disengage their contacts and thus break the power circuit to the pump motor. Due to this power failure, the relay coil 52 will be deenergized, which will allow the switch arm 53 to engage the contact 55 and thereby condition the motor 45 for driving the valve5 to closed position when power service is resumed. Upon resumption of power service the timer 40 will be cooled and therefore the mercury switch 43 of this timer will be opened. This will prevent energization of the starter coil l2 and consequently of the pump motor ill until the expiration of a timed period following the resumption of power service. Immediately upon the resumption of power service the motor 45 will begin to drive thevalve 5 to closed position. By designing the timer t!) so as to have a greater timing than the-period of time required for closing of the valve 5, it will be assured that the valve 5 will reach closed position beforethe restarting of the pump following a power failure. The timer 40 therefore has the added function of permitting the valve 5 to close before energization of the pump following a power failure.

From the foregoing description it should be apparent that my invention provides for preventing surges in a water distribution system due to starting and stopping of the pump. This result is achieved by the use of a valve in the pump discharge and of automatic control means for maintaining the valve closed until after the pump has started and for closing the valve before stopping of the pump. Also it will be apparent that my invention provides for maintaining proper operation of the surge preventing system upon resumption of power after a power failure, provides for preventing the pump from being started by a momentary drop in pressure, and, further provides for back-spin protection of the pump. While I have shown and described my invention as applied to a system of the type utilizing a single pump which is stopped and started, it will be apparent that certain features of the invention are applicable to systems utilizing a number of pumps operated in sequence or to systems in which the speed or output of the pump is varied. Also, while the invention has been described as applied to a liquid pumping system, certain features of the invention are applicable to other types of pumping arrangements such, for instance, as blower systems. In addition, while the valve has been illustrated as located in the pump discharge, it will be understood that for different types of installations the valve position may be varied. For instance, it may be located in the intake line to the pump or may be located in a by-pass around the pump. As many other modifications and applications of my invention will occur to those skilled in the art, I desire to be limited only by the appended claims as construed in the light of the prior art.

I claim as my invention:

1. In a system of the class, described, in combination, fluid forcing means for inducing a flow of fluid from one point to another, means for driving said fluid forcing means, a power controller for controlling the supply of power to said driving means, said power controller being arranged to break the power connection to said driving means upon a failure of power, a device for controlling said power controller, flow control means for controlling the flow of fluid induced by said iiuid forcing means, means for controlling the delivery of power to said flow control means, said last mentioned means being arranged to place said flow control means in a flow restricting position when the supply of power is resumed following a power failure, and time de- 2. In a system of the class described, in com-- blnation, fluid forcing means for inducing a flow of fluid from one point to another, a motor for driving said fluid forcing means, flowcontrol means for controlling the flow of fluid induced by said fluid forcing means, a motor for actuating said flow control means, a magnetic controller for energizing said first motor to start said forcing means, means controlled by said magnetic con troller for also energizing said second motor for slowly moving said flow control means away from flow restricting position, a. maintaining circuit for said magnetic controller for maintaining said controller in a position for energizing said first motor, said maintaining circuit being controlled by said flow controller in a manner to close said maintaining circuit when said flow controller is away from flow restricting position, and means for causing said flow control means to be returned to flow restricting position for substantially stopping the flow of fluid and then break- .ing said maintaining circuit for placing said fluid forcing means out of operation.

3. In a. pumping system, a pump, a source of fluid supply, a pipe for conveying fluid from said pump to a point of use, a valve in said pipe, a motor for driving said pump, a motor for opening and closing said valve, said valve motor and valve both being incapable of movement upon a failure of power to said valve motor, a. starter for said pump motor, a controller for said valve motor to cause it to slowly open said valve, said pump starter causing operation of said valve controller, a switch for operating said pump starter, a timer for actuating said switch, means responsive to a demand for fluid for energizing said timer to start said pump and open said valve, said means operating said valve controller when said demand for fluid has been satisfied for cansing said valve motor to slowly close said valve, and means actuated by said valve motor for deenergizing said pump when said valve has reached closed position.

4. In a pumping system, a pump, a source of fluid supply, a pipe for conveying fluid from said pump to a point of use, a valve in said pipe, 2. motor for driving said pump, a motor for opening and closing said valve, said valve motor and valve both being incapable of movement upon a failure of power to said valve motor, a starter for said pump motor, a controller for said valve motor to cause it to slowly open said valve, said pump starter causing operation of said valve controller, a. switch for operating said pump starter, a timer for actuating said switch, means responsive to a demand for fluid for energizing said timer to start said pump and open said valve, said means operating said valve controller when said demand for fluid has been satisfied for causing said valve motor to slowly close said valve, and means actuated by said valve motor for deenergizing said pump when said valve has reached closed posi tion, said pump starter being such that on a power failure it moves to pump deenergized position, said thermal timer delaying the reoperation of said pump starter on a resumption of power until a sufiicient period of time has elapsed to permit said valve motor to close said valve.

CHAUNCEY M. BUCK.

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