US1980799A - Control system - Google Patents

Description

Nov. 13, 1934. c, HARDESTY 1,980,799

CONTROL SYSTEM Filed March 1, 1953 Inventor- LJewell gn C. Hardesb g,

His Attorne g.

I driven pump.

Patented Nov. 13, 1934 1,980,199 CONTROL SYSTEM I Llewellyn C. Hardesti,

Scotia, N. r., minor to General Electric Company, a corporation oi New York Application March 1,

'1 Claims.

This invention relates to control systems, more particularly to fluid control systems, and it has ior an object the provision oi a simple, reliable, and emcient system oi this character.

The invention is illustrated in one iorm thereoi as embodied in a fluid control system in which the fluid is circulated by means oi a motor In carrying the invention into eiiect in one iorm thereoi, means are provided ior starting the pump motor, and means are also provided ior stopping the pump motor ii fluid does not start to flow within a predetermined time interval aiter starting the pump together with means ior preventing the restarting oi the pump ior a predetermined time interval.

For a better and more complete understanding of the invention reference should now be had to the iollowing specification and to the ac-v companying drawing the single flgure 0! which is a simple diagrammatical sketch oi an embodiment oi the invention.

Reier ing now to the drawing, a fluid, such i'or example as water, is circulated by means oi a pump through a fluid system illustrated in the drawing by the pipe 11 and the surge tank 12. The pump is driven by any suitable driving means such for example as thatrepresented by the electric motor 13, illustrated as an alternating current type motor supplied from a suitable source represented in the drawing by the three supply lines 14 to which the motor terminals are connected by means oi the three conductors 15. The starting and acceleration oi the motor 13 are controlled by primary resistance sections l6, l7, and 18 which in turn are under the control oi suitable switching apparatus illustrated as comprising accelerating contactors 20, 21, and 22 and a line contactor 23.

A pressure governor 24, responsive to changes in fluid pressure within the surge tank 12, serves to control the starting and stoppin oi the motor l3 automatically, while suitable manually operated control devices illustrated as a switch-'- ing device 25 with normally open contacts and a switching device 26 with normally closed contacts serve respectively to start and stop themotor. Suitable means 2'7 illustrated as a switching device serves to transfer the control from hand to automatic and vice versa. When the switching device 2'1 is in the pos'tion in which it is illustrated, the starting and stopping of the motor is under the control of the manually operated start and stop push-buttons 25 and 26, whilst when the device 2'? is operated to its other position, the starting and stopping oi the motor is under the control oi the pressure governor 24.

In order to prevent water'hammer or other undesirable operating conditions in a fluid circulating system likely to arise ii the fluid does clock switch 36 are operated 1933, Serial No. 859,057

not start to circulate within a predetermined interval oi time aiter the pump 10 has started, the line contactor 23 is provided with a time element device 28 which cooperates with an auxiliary interlock on the flrst accelerating contactor 20 and with a control relay 30 to stop the pump motor ii fluid does not start flowing within a predetermined time after the pump is started.

A no flow device 31 illustrated as a fluid flow responsive relay cooperates with a control relay 32 to prevent the time element device 28 and the interlock 20. irom stopping the motor 13 ii luid starts to flow in the pipe 11 within the time interval determined by the setting of the time element device 28. A time element device 33 serves to prevent restarting oi the pump within a predetermined time interval after the operation 01! the time element device 28 and interlock 20. to stop the pump motor. For the purpose of rendering the no flow device 31 ineiiective ii desired, a switching device 34 is provided. This switching device has two positions; an upper position in which the contacts oi the relay 30 controlled by the no flow" device 31 are short cirsuited and a lower position in which the contacts oi the no flow device 31 are connected to one side oi the supply source. A clock switch 36, illustrated as comprising a small salt-starting synchronous motor 3'? and a movable contact member 38 driven thereby, serves to render the controlling apparatus efiective ior certain hours oi the day and ineflective for the remaining hours oi the day. I! it is desired'to operate the system at a time when the controlling apparatus is rendered ineiiective by the position oi the contact oi the clock switch, a manually operated switching device 3'1. is provided ior short clrcuiting the contacts 0! the clock switch. I

with the above understanding oi the elements and apparatus and their organization in the completed system the operation oi the system ltseli will readily be understood irom the iollowing detailed description: ,5

Assuming that automatic operation oi the system is desired, the switch 27 is operated to the automatic position in which its movable contact member 27. is in contact with its cooperating stationary contact members 27b and in which its left-hand movable contact member 27 bridges the cooperating upper stationary contacts 27d. Further assuming that it is desired to render the no flow device 31 eilective, the movable contact of switching device 34 is operated into engagement with its lower cooperating stationary contact members 345. 7 At some predetermined time oi day the movable contact members 38 oi the into engagement with the pawl oi the contact arm 40, which is connected by means oi a spring with another con-' tact arm 41, thereby constituting an over-center switch. As the contact 38 engages the pawl 01' contact 40, the latter is operated into engagement with stationary contact 42.

It the fluid pressure in the surge tank drops conductor 56 line as before.

tactor 23 and thence by conductor 61 to and through the left-hand side of switch 46 of the upper supply line 14. Accelerating by conductor 64 to and through the operating coil of accelerating contactor 21 and thence by conspeed of the motor 13, as is well understood' In a similar manner, accelerating contactor 22 is 7 energized and closed to short circuit the resistby the setting 01' time element device 66. Line contactor 23 in responding to the energization of he drawings. Contactor 20, in opening, causes interlock contact 20a to engage its lower cooperating stationary contact members.

If fiuid starts to flow in of the no flow device 31 is actuated into engagethence by conductor 61 to the upper 14 as previously traced.

Control relay 30 in responding to the energization of its operating coil disengages its movable 1 contact member from engagement with its stationary contact members, thereby opening the ratus in the previously members 28., circuit previously traced through these contacts for the operating coil of the control relay 30. 11! control relay 30 were to become deenergized and allowed to reclose its contact, it would be possible for the pressure governor 24 to restart the appadescribed manner. This, however, would cause water hammer, or other undesirable operating conditions in the line 11 and is prevented by operation of the time element device 33.

when the contacts 28. of the time element interlock 28 were bridged to complete the energizing circuit for the operating coil of relay 30, an energizing circuit was also completed for the operating coil '77 of the time element device- 33. This energizing circuit is traced from the lower supply line 14 to the conductor '73, as previously traced, thence through the operating coil '7'! and by conductors '78 and 61 and switch 46 to the upper supply line 14. Energization of the operating coil '77 attracts movable contact into engagement with its cooperating stationary contact 81, thereby completing a holding circuit for the operating coil of control relay 30 independently of the stationary contact 28a of the time element interlock 28, which holding circuit is traced from the lower supply line 14 to the conductor '71 as previously traced, thence by conductor'82, contacts 81 and 80, contacts '74 and '75, conductor '76, operating coil of control relay 30, and thence by conductor 61 to the upper supply line 14 as previously traced. It will also be clear that a holding circuit is established for the operating coil 7'7 that is traced from the lower supply line 14 to the conductor '71 as before and thence by conductor 82, contacts 81 and 80, coil '77 and thence by conductors '78 and 61 to the upper supply line 14. As contact 80 is drawn into engagement with its stationary contact 81, the L-shaped member 83 is rotated about a pivot 84 in a clockwise direction. The shaft 85, one extremity of which is journaled in the L- haped member 83, is allowed to descend thereby moving the worm 86 into engagement with wormwheel 8'7. At the same time the hook member 88, which is attached to the movable contact member 80, engages the upper extremity of contact '74, thereby biasing the latter in a clockwise direction. Contact '74, however, is prevented from clockwise rotation by the pawl at the left-hand end of the lever 90. The closing of contacts 80 and 81 also completes a circuit for the operating coil of the disc motor 91, which circuit is traced in the lower supply line 14 tothe conductor 82 as before, thence through contacts 81. and 80, contacts '74 and '15, conductor '76, operating coil ofdisc motor 91 and thence by con'duc-- tors '78 and 61 to the upper supply line 14.

It will be clear that the operating coil of the control relay 30 is in parallel with the operating coil of'the disc motor 91, and consequently as long as the'latter is energized the control relay 30 is also energized and its movable contact member is held in its upper open position thereby preventing the system from being restarted. The disc motor 91 rotates the worm 86 and likewise the wormwheel 8'7 in a clockwise direction and at a speed that is preferably substantially constant. As shown in the drawing, the wormwheel 8'7 is provided with a pin 87a. After a predetermined interval of time this pin engages the right-hand extremity of the lever 90 thereby rotating the latter in a counter-clockwise direction about the pivot 90a. This counter-clockwise rotation of the lever 90 disengages the pawl from the contact thereby interrupting the energizing 3 member '74 which, as previously stated, is biased for clockwise rotation by the hook 88. Thus as the pawl of the lever 90 is disengaged from the contact '74, the latter is disengaged from the movable contact '75, thereby interrupting the energizing circuit for the operating coil of the disc motor 91 previously traced through contacts '74 and '75. As a result, the rotation of the disc motor 91 is stopped and since the the coil of control relay 30 is in parallel with the operating coil of the motor, the relay is likewise deenergized and its movable contact member is allowed to descend into engagement with its cooperating stationary contact, thereby leaving the control system in a reset condition. The pump motor 13 is now restarted in the previously described manner. It will thus be seen that if fluid does not start to flow in the line 11 within a predetermined interval of time after the closing 'of the line contactor, the pump motor 18 is shut down and cannot be restarted for a predetermined interval of time, determined by the time element device 33.

However, if fluid starts to flow in the line 11 within the predetermined time interval, the pump is not shut down, but continues to operate until sufficient pressure is built up in the surge tank 12 to cause the pressure governor 24 to operate its movable contact member 43 into engagement with the upper stationary contact member 439. short circuiting the coil of the pressure governor relay 45. This short circuiting of the coil of the pressure governor relay causes the latter to open its contact and interrupt the energizing circuit of the line contactor 23 previously traced through the lower contact of the pressure governor relay. The line contactor 23 opens its contact in response to the interruption of its energizing circuit and disconnects the pump motor 13 from the supply source 14, thereby shutting down the pump.

A subsequent drop in the fluid pressure within the surge tank causes the above described operation to be repeated.

If manually controlled operation is desired instead of automatic operation, the transfer switch 27 is operated to the position in which it is illustrated in the drawing. To startthe pump motor 13 the start button 25 is operated to the closed position in which it completes an energizing circuit for the operating coil of the pressure governor relay 45, which circuit is traced in the lower supply line 14, through the right-hand contact of switch 46, conductors 4'7 and 48, contacts of control relay 30, conductor 51, contact 27c and lower stationary contacts of the transfer switch, conductor 94, normally closed contacts of stop button 26, intermediate and right-hand stationary contacts of start button 25 bridged by the movable contact member, conductor 95, operating coil of pressure governor relay 45 and thence by conductor taneously an energizing circuit is completed for the operating coil of accelerating contactor 20, this circuit being traced from the'lower supply line 14 to the start button 25 as before, and thence by conductor 58 to and through the operating coil of contactor 20, and thence by conductor 60, normally closed interlock contacts 23a, 23b, and conductor 61 to the upper supply line 14. Contactor 20 closes in response to the energization of its operating coil and its interlocking contact 201 completes a holding circuit independently of the start button 25. This circuit is traced from the lower supply line 14 through the stop. button 26 as before, thence by conductor 53, lower contact of pressure governor relay 45, conductor 5'7,

56 to the upper supply line 14. Simul upper contacts of transfer switch bridged by movable contact 2711, conductors 96 and 97, upper auxiliary stationary contact 20b bridged by the movable contact 20a and thence by conductor to the upper supply line 14 as It is also upper contact of pressure governor relay 45,

v pressure govand thence by conductor 56 to the Since self holding circuits for the pressure governor emor relay upper supply line 14. are estabiished both What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a fluid pump control system, a pump, means responsive to a pressure condition in said system for starting said pump, means responsaid motor, means responsive to fluid flow and a time element device cooperating therewith for stopping said motor for a predetermined interval of time.

3. In a fluid pump control motor.

4; A fluid flow control system for a pump comprising a motor for driving the pump, switchmeans for controlling said motor, means for actuating said switching means to start said motor, means for actuating said switching means to stop said motor upon failure or fluid to flow termined interval of me.

5. A fluid pump control system comprising a motor for driving the pump, means for controlling the supply to said motor 6. A fluid pump control system comprising a motor for driving the pump, means for controlling the supply to said motor comprising switchdevice for preventing restarting of said motor within a predetermined time interval.

7. A fluid pump control system comprising a motor for driving the pump, speed controlling terval of time.

EWELLYN C. HARDESTY.

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