US2389348A - Pump control system - Google Patents

Description

R. c. DusTlN 2,

PUMP CONTROL SYSTEM Nov. 20, 1945.

Filed-Aug. 1o, 1942 Ha/0h H @Bam/Q22.

Patented Nov. 20, i945 TENT x 1" CGNTL SYS'E Ralph C.

Massachusetts Dustin, Claremont, BKH., assigner' to Sullivan Macery Gompamy,

a corporation or Application August w, 1941.2, Serial No. 454,219

n 16 Claims. (Cl. 23o-18) My invention relates to control systems for pump mechanisms, and more particularly to sys tems for controlling automatically the operation of a. motor driven compressor.

In the operation of a motor driven compressor, it is desirable to avoid the stopping and starting of the motor except at times when the discharge of fluid from the compressor will not be needed for a period of such length that a saving of power may be obtained by shutting down. the motor. When the compressor discharges fluid to a receiver and the maximum desired receiver pressure is reached, the discharge of fluid may he discontinued by a compressor unloading device actuated by the receiver pressure. Such an unloading device ordinarily holds the compressor unloaded until the receiver pressure drops from a maximum to a predetermined lower value. If no uid is being used from the receiver when the maximumpressure is reached, or, if fluid is being used at this time but its use is discontinued before the lower pressure value is reached, then it may be a considerable time before the receiver pressure drops to the lower pressure value. In such a case it is desirable that the compressor be unloaded and that its driving motor be stopped. If fluid is being used from the receiver at the time the maximum pressure is reached and will be used continuously until the pressure drops to the lower value, then the compressor should be unloaded but the motor should be kept ruiming since the time required for the pressure drop to take place is comparatively short and the stopping and starting of the motor results in a greater inefficiency. t

The above desired control of the compressor and the driving motor is made possible in this invention by providing a iiuid actuated unloading mechanism for the compressor, and a normally closed fiuid actuated switch in the motor circuit. When the maximum desired pressure limit is reached, pressure responsive means operate to supply pressure fluid to the unloading means and, if no uid is being discharged from the receiver, to supply pressure fluid to open the switch. 1f luid is being used from the receiver at the time the maximum pressure is reached, a valve is closed so that no pressure fluid can flow to the switch. As long as iluid continues to flow from the receiver, the valve is held closed and the motor circuit remains unbroken so that the motor continues to operate. If the flow of iluid from the receiver is discontinued before the lower pressure is reached, then the valve is opened and uld ows to the switch,' opening the latter and Vstopping the motor. When the motor switch is once opened it will not close again until the pressure responsive means operate to vent the pressure uid from the switch.

An object of this invention is to provide an improved control system for a pumping mechanism. Another object is to provide an improved control system for a motor driven compressor. Still another object is to provide a motor driven compressor having improved means for controlling the stopping and starting of the motor in accordance with the compressor discharge pressure and the ow of fluid to a point of use. Another object is to provide a motor driven compressor. having improved means for eecting a driving of the compressor unloaded when a predetermined maximum discharge pressure is reached andA fluid is being delivered to a point of use. Yet another object is to provide a motor driven compressor having improved means for edecting a stopping of the motor with an unloading of the compressor when a predetermined maximum discharge pressure is reached and no duid is being delivered to a point of use. Another object is to provide a motor driven compressor having improved means for effecting a driving of the compressor unloaded when a maximum receiver pressure is reached and fluid is iicwing from the receiver to a point of use, but operating to stop the motor when the flow of fluid is cut ofi and holding the motor stopped until a predetermined lower receiver pressure is reached. Other objects of the invention will appear more fully in the course of the following description.

En the accompanying drawing, in which one illustrative embodiment and a modication of my invention are shown,

Fig. l is a diagrammatic view showing a motor driven compressor having my improved control system associated therewith.

Fig. 2 is an enlarged sectional view of the compressor unloading mechanism.

Fig. 3 is a, fragmentary view showing a modi; cation.

In the illustrative embodiment of the invention there is shown a motor i having its power shaft 2 connected in driving relation with a pump or com pressor It. The compressor shown herein is of the two cylinder single stage type. but it will be understood that my invention is equally applicable to any of the general types of compressors. The uid is discharged from the compressor through a suitable pipe connection t into s. receiver tanlr t from which it may be supplied through an outlet 8 to any point of use.

gagement with the inlet valve.

Associated with each of the compressor cylinders is a iluid actuated unloading generally designated I3. This unloading mecha- Y nism comprises, as shown in Fig. 2, a piston II iixed to the piston and carries at its inner end a forklike member I9 adapted to lengage the inlet valve 20 and hold the latter from its seat 2i. Surrounding the piston rod is a coiled spring 23 acting between the member I4 at the inner end of the bore I2 and the piston I I for holding the forklike member I9 normally in a position out oi en- Pressure iluid for operating the unloading mechanisms is supplied from the receiver under the control of a pilot valve 25'to a conduit 25 which is connected by branch conduits 21 in communication with the outer ends of the bores i2. The pilot valve 25 operates at a predetermined maximum receiver pressure to connect the conduit-26 in communication with the receiver, and operates again at a predetermined minimum pressure to -connect the conduit 26 in communication with atmosphere. When the bore I2 is vented through conduit 26 to atmosphere, the forklike member i9 is held by the spring 23 out of engagement with the inlet valve so that the latter operates normally to control the iiow of fluid to the cylinder bore where it is compressed and then discharged past a discharge valve 29 to a passage 30 communicating with the conduit 5. When pressure fluid is supplied from the receiver to the bore I2, the piston II is forced to the right in Fig. 2 causing the inlet valve to be unseated by the member I9 and effect an unloading of the compressor.

The motor I is supplied with electric current i'rom power lines 32, 33 and 34 under the control of a manually operated switch 35 and a uid actuated switch 36. The switch 36 is provided with an actuating arm 31 carrying a piston 36 which is reciprocably mounted in a cylinder 39. A spring 40 is arranged Within the cylinder 39 and acts against the piston to hold the switch 36 normally in its closed position. Pressure fluid for operating the switch 36 is supplied from the receiver past ing and is provided with a valve stem 54 extending through the chambers 43 and 53. Fixed to the valve stem is a valve member 55 adapted to engage a valve seat 55 surrounding the port 5I when the plunger 52 is raised. The conduits 43 and 45 open, respectively,. into the chambers 46 and 55, and these chambers normally communicate with each other through the port 5I since the valve member 55 is normally held in its open position by the weight of the plunger 52. Surrounding the plunger is a solenoid winding 58 which acts, when energized, to raise the plunger and seat. the valve member 55, thereby cutting oir communication between chambers 53 and 5l). One end of the solenoidwinding is connected by a conductor 66 to oneof the power lines on the motor side of the duid actuated switch 3B. The other end of the solenoid is connected by a conductor 6l to a switch element 62, and another element 63 of the same switch is connected by a conductor 64 to another one of the power lines on the motor side of the fluid actuated switch. The switch elements 62 and 63 are normally held apart but are adapted to be moved into engagement with each other by an arm 65 xed to a ilapper 6l which is pivotally mounted on a chamber providing member 68. The member 68 is connected in the receiver outlet 8, and the apper 6l is supported within the member 68 in such a position that iluid discharged from the receiver causes the ilapper'and the arm 55 to swing and move the switch element 53 into engagement with the element 62. When the ilow of uid through the outlet is stopped, the iiapper drops into engagement with a seat l0 surrounding a port 'Il at the'admission side of the member 66, and the arm 56 swings with the flapper to release the switch element 63 from the element 62.

The operation of the mechanism described is as follows: Assuming that the receiver pressure is low and that the pilot valves 25 and 42 are in positions venting the conduits 26 and' 43, then the compressor with be loaded and the switch 35 will be in its closed position. If the manually operated switch is then closed, the motor will operate and a pilot valve 42 to a conduit 43 which is connected through a valve mechanism, generally designated 45, to a conduit 45 communicating with the cylinder 33. The pilot valve 42 is like the pilot valve 25 and operates at the same maximum receiver pressure to` supply pressure :Huid to the-conduit 43 but is adjusted to operate at a slightly higher minimum receiver pressure to vent the conduit 43 so that the switch 36 may close and start the motor before the compressor is reloaded. The

same result may be obtained by providing a single drive the compressor for supplying fluid to the receiver. If the need for pressure iluid is low, the receiver pressure will build up to the maximum desired value and the pilot valves 25 and 42 will open supplying iluid to conduits 25 and 43. Fluid supplied to conduit 26 will be conducted to the unloading devices to eiect an immediate unloading o! the compressor. Fluid supplied to the conduit 43 will flow to the chamber 43 in the valve casing 48 and, if there is not enough iluid iiowing from the receiver through the outlet 6 to lift the dapper 61 and close the switch elements 62 and 63, the valve member 55 will be unpilot valve for controlling the flow of fluid relative tothe unloading mechanism and the switch 35, and restricting the venting of iluid from the unloading mechanism. Such an arrangement is illustrated-in Fig. 3 wherein 44 represents a wellknown type of device for eirecting a free supply of air to both of the lines 43 and 26 when the pilot valve 25 supplies pressure and a restricted venting oi' the pressure from the line 25 when the pilot valve 25 vents pressure. It will be seen that only' the pilotv valve 25 is needed with this arrangement.

The valve mechanism 45 is of the solenoid actuated type and comprises a valve casing 48 having chambers 45 and 56 communicating with each other throughr a port 5|. A plunger 52 is arranged in an upper chamber 53 in the valve casseated so that iiuid will tiow through the port 5I, the chamber 50 and the conduit 46 to the cylinder 39 where it will act on the piston 36 to open the switch 36. When the switch 36 is once opened, the electromagnet winding 56 cannot be energized by a closing of the switch elements 52 and 63 since the conductors 60 and 64 are connected to the power lines at the motor side of the switch. When the receiver pressure drops to the lower pressure limit oi the pilot valve 42, pressure fluid is vented from the cylinder 36 through the conduit 45, the chamber 56, port 5I, chamber 49 and conduit 43, and the switch 36 is closed to start the motor. When the pressure drops to the lower limit of the pilot valve 25, the conduit 25 is vented to reload the compressor. If iluid is owing through the outlet 6 in sufilcient quantity to lift the ilapper and close the switch elements 6 2 53 at the time the pilot valve 42 opens, then the valve member 55 will be seated and will prevent the ow of fluid to the conduit 46. The switch 3B will remain closed, and the compressor will be driven unloaded.

As a result of this invention there is provided improved means for controlling the operation of a compressor. The control system is comparatively simple and is adapted for'use in various types of pumps or compressors to improve. their elciency of operation. Other advantages of the invention will he clearly apparent to those skilled in theart.

lWhile there are in this application specifically described one form and a modiiication which the invention may assume in practice, it will be understood that these forms of the same are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a control system, in combination, a compressor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, means operative on the supply oi pressure iiuid thereto for eiecting an opening of said switch, passage means for conducting pressure fluid to said duid operated means, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure fluid to said passage means, and means responsive to the ow of pressure iluid from said compressor to a point of use for controlling the iiow of fluid through said passage means. y

2. In a control system, in combination, a compressor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, means operative on the supply of pressure fluid thereto for eiiecting an opening of said switch, passage means for conducting pressure fluid to said iiuicl operated means, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure fluid to said passage means, and means operating on the flow of pressure uid from said compressor to a point of use for cutting oi communication through said` passage means.

3. In a control system, in combination, a compressor, a motor for driving said compressor, a normally closed fluid actuated switch for controlling the supply of electric current to said motor, means for conducting actuating fluid to said switch, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying actuating fluid to said conducting means, and valve means responsive to the flow of pressure iiuid from said compressor to a point of use for controlling the iiow of uid through said fluid conducting means.

4. In a control system, in combination, a compressor, a motor for driving said compressor, a normally closed fluid actuated switch for controlling the supply of electric current to said motor, means for conducting actuating fluid to said switch, means including valve means operative at a predetermined maximum compressor discharge pressure' for supplying actuating fluid to said conducting means, and valve means operating at a predetermined flow of pressure fluid from said compressor to a point of use for preventing a flow of fluid through said fluid conducting means.

pressor, fluid actuated unloading means therefor,

a motor for driving said compressor, a normally closed switch for controlling the' supply of electric current to said motor, means operative on the Supply of pressure opening of said switch, means for `conducting pressure iiuid to said unloading means and to said iiuid operated means, means operative at a predetermined maximum compressor discharge pressure for supplying pressure iiuid to said iiuid conducting means, and means responsive to the flow of pressure uid from 'said compressor to a point of use for controlling the flow of iluid to said uid operated means.

6. In a control system, in combination, a compressor, fluid` actuated unloading means therefor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, means operative on the supply of pressure fluid thereto for eiecting an opening of said switch, means for conducting pressure iiuid to said unloading means and to said iluid operated means, means including valve means operativeat a predetermined maximum compressor discharge pressure for 'before said maximum discharge pressure is reached for cutting off communication through said iiuid conducting means to said iluidoperated 7. In a control system, in combination, a compressor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, means operative. on the supply of pressure iiuid thereto for eiecting an opening of said switch, means for conducting pressure fluid to said iiuid operated means, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure fluid to said iiuid conducting means, valve means for controlling the iiow of pressure iiuid through said iiuid conducting means, a solenoid for controlling the operation of said last mentioned'valve means, and means including a switch responsive to the flow of fluid from said compressor to a point .oi use for controlling the energizing of said solenoid.

8. In a control system, in combination, a conipressor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, means operative on the supply of pressure fluid thereto for eiiecting an opening of said switch, means for conducting pressure iiuid to said luid operated means, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure iiuid to said :duid conducting means, valve means for controlling the flow of pressure iiuid through said fluid conducting means, a solenoid for controlling the operation of said last mentioned valve means, and means lincluding `a switch closing on the flow of iiuid from said compressor to a point of use for energizing said solenoid.l

9. In a control system, in combination, a compressor, a motor for driving 'said compressor, a normally closed switch for controlling the supply of electric currentto said motor, means opera-a iiuid theretorjor effecting an means including valvev V"valve means to cut oir the 4 tive on the supply of pressure fluid thereto for -ell'ecting an opening of said switch, means for conducting pressure iluid to said iiuid operated means, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure uid to said uid conducting means, valve means for controlling the now of pressure iiuid through said uid conducting means, a solenoid for controlling the operation of said last mentioned valve means, and means including a circuit connected to the motor circuit Aat the motor side of saidnormally closed switch and a switch responsive to the flow of fluid from said compressor to a point of use for controlling the energizing of said solenoid.

10. In a control system, in combination, a compressor, a. motor for driving said compressor, a normally closed switch for controlling the supply o! electric current to said motor, means operative on the supply of pressure uid thereto for electing an opening of said switch, means for conducting pressure iiuid to said fluid operated means, means including valve means operative at a predetermined compressor discharge pressure for supplying pressure fluid to said iiuid conducting means, valve means for controlling the flow of fluid through said iiuid conducting.

means, and means responding to the ow of pressure iuid from said compressor to a point of use before said predetermined discharge pres- 13. In a compressor system, in combination, a compressor, 'fluid actuated unloading means therefor, a power unit for driving saidcompressor, means for controlling the supply of operating medium to said, power unit, fluid actuated means for positioning said controlling means and operative on the supply of pressure uid thereto for effecting a cutting off of the supply of operating medium to said power unit, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure fluid to said unloading means and to said fluid actua-ted means, and means responsive to the ow of pressure fluid from said compressor to a point of use for cutting oif the now of uid between said valve means and said iluid operated means.

sure is reached for actuating said last mentioned now of fluid through said fluid conducting means to said fluid operated means.

1l. In a control system, incombination, a. compressor, iiuid actuated unloading means therefor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric therefor,

current to said motor, means operative on the v supply of pressure fluid thereto for effecting an opening of said switch, means for conducting pressure nuid .to said iuid operated means and to said unloading means, means including valve means operative at a predetermined maximum compressor discharge pressure for supplying pressure fluid to said nuid conducting means, valve Y means for controlling the flow of uid through said uid conducting means to said uid operated means, asolenoid operative when energized .to close said last mentioned valve means, and means including a circuit connected to the motor circuit at the motor side of said normally closed switch and a switch closing on the iiow of iuid from said compressor to a point of use for energizing said solenoid.

,12. In a compressor system, in combination, a compressor, a power unit for driving said compressor, means for controlling the supply of operating medium to said power unit, uid actuated means i'or positioning said controllingmeans and operative on the supply of pressure uid thereto for effecting a, cutting off of the supply of operating medium to said power unit, means including valve means operative at a. predetermined maximum compressor discharge pressure for supplying pressure Huid to said uid actuated means, and means responsive to the now of pressure fluid from said compressor to apoint of use for controlling the now of fluid from said valve means 'tosaid fluid operated means.

i4. In a. compressor system, in combination, a compressor, a receiver for receiving fluid dis-V charged from said compressor, a motor for driving said compressor, a normally" closed switch for controlling the supply of electric current to said motor, means operative on the supply of pressure uid thereto for effecting an opening of said switch, valve means operative at a predetermined maximum pressure in said receiver for supplying pressure uid to said fluid actuated means, and means responsive to the flow of pressure fluid from said receiver for controlling the now of fluid from said valve means to said fluid actuated means.

15. In a compressor system, in combination, a compressor, fluid actuated unloading means a receiver for receiving iluid discharged from said compressor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, means operative on the supply of pressure uid thereto for eiecting an opening of said switch, valve means operative at a predetermined maximum pressure in said receiver for supplying pressure uid to said fluid actuated means and to said unloading means, and means responsive to the ilow of pressure iiuid from said receiver and operative on such ow of fluid for cutting off communication between said valve means and said iuid actuated means.

16. In a control system, in combination, a compressor, a motor for driving said compressor, a normally closed switch for controlling the supply of electric current to said motor, meansoperative on -the supplyof pressure fluid thereto for eiecting an opening of said switch, pressure nuid conducting means communicating with said uid actuated means, valve means for controlling the connection of said uid conducting means with the atmosphere and with the compressor discharge, said valve means operative at a maximum compressor discharge pressure for cutting oi communication with the atmosphere and ccnnecting said uid conducting means in communication with the compressor discharge, valve means for controlling the flow of fluid through said fluid conducting means, and means operating on the now of pressure uid from said compressor to a point of use for actuating said second to cut oi the iiow of duid through said uuid conducting means.

RALPH C. `DUSTI'N.

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