US2486256A - Pump control system - Google Patents

Description

Oct. 25, 1949. c. M. BUCK 2,436,256

PUMP CONTROL SYSTEM Filed Aug. 31, 1944 7 '5 Sheets-Sheet 1 LMC,

PRESSURE cannon 66 To arm 0mm.

Oct. 25, 1949. c. M. BUCK 2,486,255

- PUMP common SYSTEM Filed Aug. 31, 1944 3 Sheets-Sheet 2 Oct. 25, 1949. c. M. BUCK 2,486,256

' PUMP CONTROL SYSTEM Filed Aug. 31, 1944 3 Sheets-Sheet 3 FIQG 3 Patented Oct. 25, 1949 UNITED STATES PATENT OFFICE Claims. 1

This invention relates to a method of control and a control system for automatically controlling in sequence and combination pressure supply pumps which may be of equal or unequal capacities.

The chief object of this invention is to supply a closed system, such as a water distribution system,

with fluid (water) under a maximum pressure and above a minimum pressure and variable according to system demand without requiring the necessity of using a pneumatic or elevated storage tank. The invention, however, ma be utilized in such systems where such tanks now are employed, thereby permitting the extension of such a system now in use and of the latter type without discarding such tank when the system capacity has to be increased to care for increased demands incid'ent to boom growth, such as is occurring in war industry areas.

The chief feature of the invention resides in providing a floating controller for controlling a reversible electric motor driven switch control, the drive being effected through a lost motion clutch whereby this method and apparatus is successful, since the control is responsive only to stable conditions and temporary irregularities, such as a surge due to an incoming pump, or cutting out of a pump does not affect the control.

The present invention is further characterized by the fact that whenever a larger capacity pump is to be cut out it actually is held in operation until the lower capacity incoming pump (or pumps) gets up to speed so that the system at no time is without some pressure supply and especially when the actual change-over is being effected.

Briefly expressed, the present invention is directed to the accurate timing of control operation, the elimination of automatic response to distribution system surges due to starting and stopping of pumps, the opening or closing of large draw offs and the like, the elimination of uncontrolled overlap in the changing of pumps, the elimination of hunting or rapid cutting in and out of pumps, the elimination of dead spots or periods when no service fluid is delivered, and the utilization of low overall pressure differentials for automatic control, which is no more than that required for the control of a single pump.

The invention herein is specifically disclosed as applied to electrically driven pumps, but this is only for convenience and by way of example, for it can be incorporated in a system including multiple jet steam or like turbine driven pumps,

and other powered pumps. In the second instance, the control system disclosed herein would be used to open and close the valves controlling the various steam jets. Hence, herein the term switch is intended to incli'de a valve as well and such valve or valves can control the power fluid (electric current by switches), such as compressed air, steam. mercury vapor or a hydraulic medium.

Other objects and features of the invention will be set forth more fully hereinafter.

The full nature of the invention will be understood from the accompanying drawing and the following description and claims:

In the drawings Fig. l is a schematic diagram of an embodiment of the invention suflicient for an understanding of the same.

Fig. 2 is a similar diagram of a second embodiment of the invention and more particularly the control portion thereof.

Fig. 3 is a front view of a control cabinet and certain of the control elements therein.

Fig. 4 is a perspective view of the lost motion clutch.

It appears desirable at this time to state that the apparatus includes a selective cam-switch unit, which is reversely rotatable to the desired degree requiredthat is in one direction to supply increasing demand and in the other direction to reduce the supply as demand decreases. This unit is driven by a reversible control motor through a high gear reduction train or the like and at an adjustable speed. Interposed therebetween is the lost motion clutch.

This control motor is directly responsive to a pressure responsive switch in that when the pressure in the system falls to the predetermined minimum the switch makes low pressure contact to energize the control motor to rotate same and the selector switch in the direction and amount suificient to cut in an additional pump. The motor then stops, when the pressure rises.

When the new pump cuts in, if there is a surge incident thereto that momentaril runs the distribution system pressure above the predetermined maximum pressure, the pressure responsive switch then will momentarily make high pressure contact and the motor will be reversely rotated. However, the lost motion clutch prevents rotation of the selective cam-switch until the lost motion is taken up. By that time, however, the high pressure surge will have subsided so that the high pressure contact will be broken and the pump just cut in will not be cut out.

It is by reason of the foregoing that it is possible to utilize only that pressure differential necessary, due to pump characteristics, for a single pump and control any number of pumps having similar characteristics.

The selector disc driving motor may be any of several commercially available reversible gear head motors capable of being controlled forward, back and stop by a single pole double throw switch with a neutral position. This motor can be of the variable speed type since it is desirable to eliminate the necessity of changing gears or re-adjusting cams of the selective controller to obtain the timing required for satisfactory operation.

The pressure responsive switch may be one of several commercially available devices known in the art as floating controls, that is, one capable of giving the equivalent of a single pole, double throw, switching action with an intermediate neutral position.

This pressure responsive switch may consist of a single pressure unit with a high contact 64 and a low contact 63 and a mid or neutral position as shown in Fig. 1; or for more convenient adjustment, a double unit having an independent high and low pressure operated switch. In the latter case no contact is made when the pressure is above the setting of the low switch and below the setting of the high switch as the double unit has one common wire to the reversible drive motor M1 it is in eifect a single unit and is so considered in this description.

The time delay device, hereinafter to be referred to, can be a commerciall available instrument which essentially consists of a synchronous motor, solenoid, pawl and ratchet and switch and operates as follows: When an external control switch is closed, this device resets immediately and closes a load circuit. When the external control switch is opened this time delay device opens the load circuit after an adjustable time delay interval has elapsed. The load circuit remains open until the external control switch is again closed when the time delay device again resets and closes the load circuit. In view of the foregoing no further explanation or description is necessary. However, other equivalent devices may be employed in lieu of that specifically mentioned herein.

The lost motion clutch can be of any suitable type such as illustrated in Fig. 4 herein wherein a the control motor reduction drive is connected to a shaft l carrying two adjustable fingers II and i2 suitably secured thereto by collars l3 and I4 in adjusted angular spaced relation as at l5 and I6. These may be adjusted to provide any desired time delay since the motor is of constant though of adjustable speed type. Positioned between the fingers is the pin I! carried by arm l8 rigid with shaft IQ of the selector cam-switch unit having adjustably mounted thereon the cams 20 with which are operatively associated the fingers 2| mounting switches such as mercury switches 22 or operating Mu switches or the like.

Shaft I9 is step-by-step operable in either direction and by the reversible control motor 23 that has a speed adjusting hand control 24, see Fig. 3. By this control and adjusting the angular spacing of arms II and 12, the desired time delay incident to lost motion pickup can be adjusted as for example 30 seconds. This prevents selector shaft reversal more than once in every half minute and as hereinafter pointed out this eliminates hunting of the pumps, or the repeated cutting in and out of same which should occur due to substantially instantaneous pressure response of the motor pressure responsive controller per se to be herein described.

In Fig. 1 of the drawings 25 indicates a reservoir, 26 a supply line therefrom connected as at 21 to the intakes of three pumps 28, 29 and 30. each of the desired capacity. These intakes have control valves 3| therein. The discharges 32 include check valves 33 and manual valves 34.

Each pump is motor driven and herein motors 35, 36 and 3'! drive pumps 28, 29 and respectively. Each motor is connected to a supply of energy, such as supply lines 38 as at 39 through a suitable motor starter device 40. Each motor starter 40 is remotely controlled by another time delay device indicated generally by numeral 4| and to which reference has heretofore been made specifically. This delay device is in two sections, the switch section Nb and the time delay section 4|a.

In the former is included the contactor 42 and solenoid relay 43 controlling same. Normally contactor 42 is in open circuit position and controls a normal voltage circuit to the motor starter 40 for automatically closing the switch means therein for connecting the pump motor to the supply lines and the starting of said motor when relay 43 is energized.

A switch contactor 44 controls a normal voltage circuit to the time delay device 4ia so that when contactor 44, normally in open circuit position. is moved to closed circuit position by another solenoid relay 45, the time delay device 4|a is energized as well as solenoid 43, whereupon the motor starter is remotely controlled to effect motor starting.

When solenoid 45 is deenergized contact 44 drops to open circuit position and the time delay device becomes operative to mechanically maintain the circuit including solenoid 43 closed until the elapse of the predetermined interval.

At the time contact 44 drops to open circuit position another relay 45 is energized to cut in another pump. However, to bring this pump up to speed requires some time, hence determinable by the pump characteristics, this time delay device holds the first pump in operation until the second pump has been cut in and is operating. This overlapping of pumps produces a momentary upsurge in the distribution system, which will be reflected in the pressure responsive switch and the operation of the selector switch motor. However, due to the lost motion clutch, such motor operation is not translated to the selector switch device. Hence transient effects are cancelled from the system.

Referring again to Fig. 1, it will be noted the pump header 5| not only discharges to the distribution system but to a branch 52 therefrom. This branch includes adjusting valve 52a, gauges 53, strainer 54, control orifice 55 and riser 56 to the pressure responsive switch beforementioned. This line also includes relief valve 51 set for a safe pressure. The relief line then wastes to a drain as at 58. A bypass 59 also connects thereto and includes valve 60.

A pressure responsive element such as a sylphon or diaphragm in the housing 6| is suitably connected to a switch member 62 and the opposed contacts 63-64 may be adjusted for any predetermined pressure diiferential and low and high pressures. The three current lines 65666'l lead from this pressure responsive switch to the control motor 68 which is a low voltage reversible motor supplied by secondary 69 of a transformer having primary Ill connected to supply lines LI and L2.

Tapped thereto are lines H .and 12 leading to all relays 45 and 43, motor starters and time delay devices 4la as aforesaid. These lines are controlled by switch 13. Herein five switches I6 are connected to line II by line 14. Line I5 connects one side of the five relays to line 12. Depending upon which switch Hi is'closed by the selector cam, the associated relay 45 will be energized.

In Fig. 1 the fifth switch 16 is shown closed wherefore the fifth relay 45 is energized to close contactor 44 of the fifth relay structure. This includes two other contactors 44c and 44d. The fourth relay structure includes contactors 44 and 44b, while the third relay structure includes contactors 44 and 44a.

Each time delay device 4lb has two lines H and I8 thereto. Contactor 44 of the first relay, contactor 44 of the third relay and contactor 44d of the fifth relay is arranged to short circuit these lines to the first time delay device. Contactors 44 of the second and third relays and contactor 44b of the fourth relay and contactor 440 of the fifth relay, each are arranged to short circuit lines '|'|'I8 of the second time delay device 4 lb. Contactors 44 of the fourth and fifth relays are arranged to short circuit lines 11-18 of the third time delay device 4lb.

By this arrangement any predetermined combination of pumps can be cut in depending upon which cam actuated switch 16 is closed. Whenever it is desired to have the minimum capacity pump operate continuously jumper I9 is utilized.

As illustrated in Fig. 1, each of the mercury switches, that is the four to the right, are shown providing a switch at the back end that is normally closed when the switch at the front or forward end is normally open. Accordingly, therefore, the forward end of the left hand switch 16, is operative when the jumper I9 is not included, or to have the interlocking effect thereof, even when the jumper is included, it will be noted that each of the four right hand switches breaks the circuit for the preceding switch to the left when the one to the right is made. This provides an interlock of electrical character and such an interlock is also disclosed in Fig. 2 by means of a switch that is independent of these mercury switches.

The time delay device 4|b has been briefly described. To further disclose the wiring of same it will be noted line H connects to motor 80 and relay Bl. Relay 43 of device 41b connects to contact 82 to which the other side of motor 80 is connected. Switch member 83, when in closed circuit position, contacts contact 82 and connects same by line, 84 to supply line 12. Since the fifth relay 45 is energized all switches 83 are closed.

The other side of the time delay relay 8| is connected by line 85 to line 18. As long as any relay 45 is energized the associated contactor or contactors closes or close the circuit or circuits to the relay or relays 8|, thus closing the circuit to the relay or relays 43. At the same time the motor 80 is energized which through the pawl and ratchet, etc., resets the time delay structure. Whenever this solenoid 45 is deenerized all circuits controlled thereby are deenergized, except the reset controlled circuits, which are associated with contact 83, the time delay device holding this contactor closed, even though its relay BI is deenergized. This held condition is maintained for the adjusted interval which is that required for any pump to get up to speed. Upon elapse of this interval, the held switch 43 moves to open circuit position No further description is believed necessary relative to Fig. 1 and what is illustrated therein, or what has been described with reference there- In Figf 2, to which reference will now be had briefly, it will be noted that the pressure switch A is of dual type instead of single alternative type as in Fig. 1. Herein each of the relays R have their common connection controlled by normally closed contactors of succeeding relay structures, so that any energized relay will automatically cut out any preceding relays.

In Fig. 2 the several elements are disclosed in open circuit condition, whereas in Fig. 1 the full capacity was called for and the several circuits conditioned to supply the same. Herein also a manually operable low and high pressure switch structure is interposed between the pressure switch A and control motor M and is, in effect, in multiple with the former. Also herein the cam actuated switches include limit switches 9| and 92 connected as illustrated. The several circuits between the relays and the cam-switches also are different but functionally are similar.

If the three pump control is associated with pumps of 200, 400 and 800 G. P. M. capacities, it is obvious that demands of 2, 4, 6, 8, 10, 12 and 14 hundred gallons per minute can be satisfied therewith at the desired average pressure, the system functioning on the predetermined desired differential, and with the desired overlaps, and lost motion intervals.

When a plurality of pumps of like or unlike capacities are arranged for straight sequence control, obviously each successive pump cut in merely adds its capacity to that already applied to the distribution, so that there is no selective cut out required and, therefore, no time delay is necessary, so that the time delay relay device shown may be omitted, because on decreasing demand each successively cut in pump is cut out in reverse order of cutting in. In other words, if ten pumps were used and the demand wentto the eighth or tenth pump, the eighth or tenth pump respectively, upon decreasing demand, would be cut out, then to decrease the 7th or 9th pump respectively would next be cut out and so on to the minimum demand, which would be carried by pump #1.

While Fig. 1 illustrates three pumps with three individual controls and a five unit control thereof and Fig. 2 illustrates three individual controls for three pumps and seven individual unit controls for the aforesaid three controls, it is to be understood that the structure shown in Fig. i can be extended to a seven unit control, instead of the five unit control actually illustrated and without any invention following the broad disclosure of Fig. 2.

While the invention has been illustrated and described in great detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character.

The several modifications described herein as well as others which will'readily suggest themselves to persons skilled in this art, all are considered to be within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. In combination with a plurality of fluid supplying units each having independent power means and each connected to a common distribution line and a control individual to each power means to cut the associated unit into and out of the line, the combination of a single differential pressure operable means responsive to line pressure, reversible motive means controlled by the single pressure operable means, means selectively controlling the several power means individual controls, a lost motion connection between the selective means and the reversible motive means, and a time delay device associated with each power control for retaining a unit to be cut out in the cut in relation until the unit to be cut into the line becomes eiIective thereon.

2. A combination as defined by claim 1 wherein the time delay device is of adjustable character for varying the time delay interval.

3. In combination with a plurality of fluid supplying units each having independent power means and each connected to a common distribution line and a control individual to each power means to cut the associated unit into and out of the line, the combination of a single differential pressure operable means responsive to line pressure, reversible motive means controlled by the single pressure operable means, means selectively controlling the several power means individual controls, a lost motion connection between the selective means and the reversible motive means, and a time delay device associated with each power control for retaining a unit to be cut out in the cut in relation until the unit to be cut into the line becomes effective thereon and the difierential pressure operable means is of adjustable character. 1

4. In a fluid distribution system, a plurality of units to supply fluid under pressure to said system, a power source for operating each of said units, means operable automatically between predetermined high and low pressure limits for energizing or deenergizing said power sources, and means connected with each of said power sources to continue operation thereof a predetermined time after said automatic means has operated to deenergize said power sources.

5. In a fluid distribution system, a plurality of units to supply fluid under pressure to said system, a power source for operating each of said units, means operable automatically between predetermined high and low pressure limits for energizing or deenergizing said power sources, and time control means connected with each of said power sources and operable to maintain a power source in operation a predetermined time after said source has been deenergized.

6. In a fluid distribution system, a pair of pumps to supply fluid under pressure to said system, a power source for operating each pump, means operable automatically between predetermined high and low pressure limits for energizing or deenergizing said pumps, a time controlling mechanism, and means governed by said time controlling mechanism for maintaining one of said pumps in operation a predetermined time after said automatic means has operated to deenergize the said one pump.

7. In a fluid distribution system, a series of independently operated pumps to supply fluid under pressure to said system, means operating automatically between predetermined high and low pressure limits for energizing said pumps luccessively, pressure operating mechanism operable automatically to energize said pumps in sequence, and means interposed between said flrst mentioned pressure operating means and acid sequence control mechanism to prevent energizing of any of said succeeding pumps for a predetermined time period.

8. In a fluid distribution system, a series of independently operated pumps to supply fluid under pressure to said system control, means operating automatically between predetermined high and low pressure limits for energizing and deenergizing said pumps successively, pressure operating mechanism operable automatically to energize and deenergize said pumps in sequence. and means interposed between said pressure control meansand said sequence control mechanism to prevent energizing and deenergizing, respectively, of any of said succeeding pumps for a predetermined time period.

9. In a closed pressure distribution system the combination of a plurality of independent pressure fluid supply units, each normally operable between predetermined high and low pressures, a source of power for each unit, a control device responsive to distribution system pressure within predetermined high and low pressures therein for controlling the sources to effect deenergization and energization respectively of a unit upon rise and fall of system pressure above and below the last mentioned pressures, the latter being within the range of the flrst mentioned pressures, and time delay means operatively associated with the control device for delaying tor a predetermined time the energization of an incoming unit and deenergization of an outgoing unit respectively upon fall and rise of distribution system pressure, the second mentioned pressures each being comparatively close to an average pressure to be maintained in said system.

10. In a pressure distribution system a plurality of independent pressure fluid supply units, an independent power supply for each unit, a distribution system high and low pressure operable single control operatively connected to said power supplies for energizing and deenergizing individual units upon system pressure falling and rising respectively to the said low and high pressures of said system, and a single time delay device interposed between said single control and the said power supplies to retard energization and deenergization for a predetermined time at each such operation.

CHAUNCEY M. BUCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 826,953 Muckle et al July 24, 1906 1,009,400 Fordyce et al Nov. 21, 1911 1,050,916 Bresnahan Jan. 21, 1913 1,903,763 Hott Apr. 18, 1933 1,972,812 Walley Sept. 4, 1934 2,029,765 Durdin Feb. 4, 1936 2,237,574 Persons Apr, 8, 1941 2,246,940 Hood June 24, 1941

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