US2384894A - Automatic pump speed control - Google Patents

Description

Sept. 18, 1945. R. R. CURTIS AUTOMATIC PUMP SPEED CONTROL 2 Sheets-Sheet 1 Filed Nov. 7, 1942 M517 5741 "@3591: Wax/id's p R. R. CURTIS 2,384,894

AUTOMATIC PUMP SPEED CONTROL Filed Nov. 7, 1942 2 Sheejg-Sheet 2 f5 2 49 22 \55 L O I53 6 lf k '3 E 19 1.. 6 5a 24. i 5 a I 5 r i 43 y 55 29 Q 4 51 z 1; r M5247] 57E Tad/55s d6 2- 00/253 Patented Sept. 18, 1945 AUTOMATIC PUMP SPEED CONTROL kusseilkcurtiabaytomohimalignartocurtis Pump Company, Dayton, Ohio, aoorporationsf Ohio Application November '1, 1942, Serial No. mm!

4 Claims. (01. sol-4s) Thi invention relates to an automatic speed control forapump,andto aliquidsupplysystem embodying such speed control and a plurality of pumps. the invention being highly desirable for useinconnectionwiththefuelsupplyforairplanes, although the invention may have other nsesandpurposesaswillbeapparenttoone skilledintheart.

In fuel supply systems. especially where a boosterpumpisusedinadditiontoamainor regular fuel pump. it ll desirable to maintain a predetermined constant pressure diiferential between the carburetor intake and the carburetor outlet to the engine being supplied with fuel. The maintenance of that predetermined pressure differential is at times extremely dimcult, and this has in the past pnoven trueespeclally in connection with the fuel systems on airplanes where the ambient-air pressureat the fuel tank varies plan'e ascends and descends, or ehangesieveisduringflisht. Inthefuelsystem on an airplane, it. is necessaryto employ additiona'lpumpmeans.suchasaboosterpump.after the plane reaches a altitude and the ambient air pressure the booster p I pressuredin'erentialover thecarburetorwillnotbehad.

, With the foregoing' in-inlnd, it is an important object of the present invention to provide an automatic speed control in a fuel system arranged mpmustbievariedinspeedinkeeping with the changingconditions'of flight. or-"the cally by a diaphragm that is responsive to changes in fluid pressure.

Another feature of the invention resides in the provision of a speed control device having a variable resistance and selection means in the form of a rocker arm with means for automatically exerting pressure onthe rocker arm in a direction substantially throuah the point of contact at all times. I

Still another feature of the invention resides in the provision of a speed control device ineluding a variable resistance with a rocker arm selection contactor, such contaotor being actuated by a fluid pressure responsive diaphragm. A further obiect of the invention is the provision of a variable resistance controlling device including a rocker armselection contactor'with pressure exerting means movable with the rocker arm to always "exert pressure in a direction through the point of contact of the rocker arm, thus giving the'double advantalsev of positive contact and the reduction to a minimum of the driving force necessary'torock the contactor in either acteristics and advantages of. the'instant sensitive to pressure occurring between a series 45 0! fuel pumps and a carburetor intake, and re-.

'sponds to variation of such pressure to maintain a proper pressure to the carburetor regardless oi! whether or not one or more pumps in the series are in peration. Y

Another object of the invention is to provide anovel speed control for an electric motors.

It I also a feature of thicinvsntion to'providsan electri moterl'pssd control embody- It is also an obiect of the invention to provide a variable resistance control device including a rocker arm contactor, with means to automatically maintain the same pressure on the rocker arm at its point of contact regardless of its position.

While some of the more salient features, charinvention have been above pointed out, others will become apparent from the .following disclosures. taken in conjunction with the accompanying drawinsainwhich: Figure 1 is a diagrammatic illustration of a fuel supply system embodying instant invention, and illustrating diasrammatlcally the controlling electrical circuit;

Flame 2 is a central vertical sectional view principles of the pump I driven by an electric motor I of which the field winding I is shown separated from the motor for the purpose of clarity.

The booster pump I discharges through a pipe I to the intake of' a main fuel pump 1 which in turn discharges through a pipe I to a carburetor I associated with an internal combustion engine II.

The booster pump I is preferably of that type wherein the inlet and outlet are always in open communication whether or not the pump impeller is in operation. The fuel pump I is of that type having a valved bypass interconnecting its intake and discharge. It will therefore be apparent that the carburetor I may be supplied with fuel from the tank I by either the booster pump I or the fuel pump 1 without the aid of the other. In the event the booster pump I operates alone, pressured fuel from this booster pump will be bypassed in the fuel pump 1 and delivered to the carburetor. In the event the fuel pump I operates alone, fuel from the tank I will pass directly from the inlet to the outlet of the booster pump I to the intake. of the fuel pump, 1, and pressured fuel will be delivered to the carburetor solely by the fuel pump I.

If this fuel system is incorporated in an airplane, after the airplane reaches a certain altitude and the ambient air pressure accordingly drops, the fuel pump I will in all likelihood not be capable of supplying fuel under the desired pressure to the carburetor, and the fuel so supplied will contain air and vapor bubbles which interfere to a material degree with the proper operation of the engine. It is then desirable to operate the booster pump I, and this booster pump is preferably of such character as to beat out the bubbles of gas and vapor occuring in the fuel in the tank I by virtue of the dropping of ambient air pressure, and deliver bubble-free fully liquid fuel under pressure to the fuel pump I, thereby augmenting the fuel pump I so that liquid under the predetermined and desired pressure is supplied to the carburetor by the combined action of both pumps. Of course, in case of failure of the fuel pump 1, it will be necessary to supply the carburetor with pressured fuel by the booster pump I alone.

The booster pump normally operates at a single low pressure speed when assisting the engine fuel pump even though the airplane may change levels during flight. But, if there is a partial or complete failure of the fuel pump I, the booster pump is subjected to emergency performance and must necessarily operate at a higher speed than when the fuel pump is operating efficiently. It is therefore desirable to have a highly accurate and sensitive automatic control over the speed of the booster pump motor, and a control that will vary the speed of the booster pump rapidly, efficiently, and accurately to a very wide increment range, in keeping with changing conditions.

To this end, I have provided an automatic speed control device generally indicated by numeral II connected in the fuel system at one end by a conduit II leading to the pipe I between the fuel pump I and the carburetor I. The other end of the c'ontrol device II is connected through a conduit or pipe II to the intake manifold of the engine II, on the discharge side of the carburetor. In the fuel supply system, therefore, the control device is shunted around the carburetor so that it will be aflected by pressure occurring on the intake side of the carburetor and the pressure on the discharge side of the carburetor, and, in response to both these pressures, will maintain the proper pressure differential over the carburetor.

Referring now to Figures 2 and 3, it will be seen that the automatic control device II includes a composite hollow casing II having a head II atone end with a threaded opening II to which the pipe II is connected. lit the other end thereof the casing II has a head II with a similar threaded opening II into which the pipe II is connected. Inside thereof, a partition II divides the easing into two chambers, an upper chamber II and a lower chamber II. The pipe II communicates with the interior of the upper chamber II through the port II and a passage II in the head II. The pipe II communicates with the lower chamber II directly through the port II.

Within the casing is a reciprocable shaft II slldable through a bearing as indicated at II in the partition II. The upper end of this shaft terminates in a hollow piston II reciprocable within a suitable cylinder bore II in the casing head II. Just below the piston II. the shaft is connected to a diaphragm Il extending entirely across the chamber II. This connection is established by means of a pair of similar upper and lower flange members II of suflicient area to maintain the central portion of the diaphragm fixed between them. Outside of this central portion the diaphragm is annularly arcuate so as to permit the diaphragm to respond to pressure set up in the chamber II.

In the lower chamber II another and similar diaphragm II is mounted across the chamber,

. and this diaphragm is anchored to the same shaft II by similar flange members II. The lower diaphragm II is responsive to pressure set up in the chamber II, communicated to the chamber through the pipe II, from the opposite side of the carburetor I. A coil spring II in the lower chamber provides an initial predetermined pressure on the diaphragm II, the pressure of this spring being augmented by pressure through the pipe II or detracted from by dropping of pressure in the same pipe, as the case may be. The partition II is preferably provided with an opening III: to vent the space between partition II and diaphragm II.

From the foregoing, it will be noted that as the pressure differential over the carburetor I varitl. the diaphragm I1 and II will reciprocate the shaft II up and down in accordance with the variance in pressure differential. As the shaft II operated by the diaphragm reciprocates in keeping with variations in pressure, it exercises a fine and continuous automatic control over the speed of the booster pump motor, by means now about to be described.

- A bracket II is moimted on a side of the casing II to project outwardly therefrom in fixed position. This bracket carries an insulation block II, which may be either solid or laminated. The end portions may be closed by additional blocks II--II. Extending through the block II is a series of contact elements II, II, II, II, II, II, II and II, of which there may be any desired or suitable number. These contact elemems tor minate at one end flush with the bottom of a groove or track II formed in the upper face of the block II. At the other end thereof. the contact members II to II inclusive are connected by conductors II, II, II, II, II, II, II and II respectively to spaced points along a resistance coil II.

The contact points between the respective eonductorsandtheresistanoseoilmayormaynot be evenly spaced, depending upon circumstances of operation. It will be seen, therefore, that if the contact member II is placed in circuit, only an end segment of the resistance coll II will be in that circuit; if the contactor I1 is placed in circuit. there will be three segments of the coil I! in circuit, and so. on until finally if the contactor I is placedin circuit, the entire coil will be in circuit.

In conjunction with the contact members I! to 42 inclusive, a selector member is provided. and in the illustrated instance this selector member is in the form of a conductiv rocker arm 83, which rides in the aforesaid groove 43 so that it is prevented from lateral displacement. Longitudinal displacement of the rocker arm ll may be prevented by any suitable means such as a spring member "a one end of which is secured to the block 34 in any suitable manner (not visible in Figure 2) and the opposite end to the far end of the rocker arm 63. This rocker arm is actuated in a rocking motion in response to reciprocatory movements of the aforesaid shaft 23 in the casing ll.

Mounted on the shaft 2! between the diaphragm 21 and the partition is is a doubleflanged collar 54. A toggle stud Bl having a ballended shank It is pivoted on a cross shaft as indicated at I! with the ball-ended shank extending between the flanges of the collar N. This stud projects through an-opening II in the casing wall, and its outward end is provided with a socket to receive the ball-ended shank I! of stud it fixedly attached to the rocker arm contactor It. It will thus be seen that when the shaft 18 moves downwardly, in the position seen in Figure 2, the rocker arm II will be rocked upwardly toward the topmost contact member 42,

- and when the shaft 28 moves upwardly, the rocker arm will be rocked downwardly toward the endmost contact member II. During movement in termediate the extreme end positions, the rocker arm will successively contact the intermediate contact members, either in one direction or the other, depending upon the movement of the shaft 23. v c

It is desirable to insure a positive tight contact between the rocker arm and each of the contact members II to 42 inclusive. To this end. a fabricated yoke ii is attached at its end portions to the fixed insulating blocks "-34, as indicated at 02C2'. Thi yoke will, therefore, be fixed in position. The cross arm of the yoke "is provided with an opening 03 through which a cup 04 extends. This cup has its opposite wall portions pivoted to the yoke II as indicated at II in Figure 3. The pivotal connections extend only into the respective wall portions of the cup,

and not entirely through the cup, so that the cup is free to pivot relatively to the yoke ll in'the same plane as the contactor rocker arm II.

Another and circumscribing yoke a has its end portions rigidly connected to the contactor rocker arm I! as indicated at 81-41. This yoke II is of sumcient size to clrcurnscribe the fixed yoke ii in spaced relationship thereto as seen clearly in Figure 2. The cross portion of this outer yoke carries a block 08 with an inwardly extending pin '0. A coiled spring II is seated in the cup ll around the pin 0. and bears against the block OI thereby urging the cross portion of s the yoke It outward-1y and causing the contactor rocker arm I: to seat tightly against the end of whatever contact I to it is engaled with at movement of the rocker arm in either direction. Thus, positive pressure of the rocker am against the end of a contact member is assured at all times, so that excellent circuit connection is established and there is little likelihood of arcing occurring, and, as well, the driving force necessary to rock the arm is reduced to a minimum.

In Figure l the contactor rocker arm II, the contact members II to II, and the coil 82 are diagrammatically illustrated in an electrical circuit establishing a speed control over the motor 4 of the booster pump 8. This circuit includes line wires H and II which may lead to any suitable source of electrical energy, such as a storage battery. One side of the motor 4 is connected through conductor II to line wire II. The other side of the motor is connected through conductor ll to the motor field I, which is in turn connected by conductor "to line wire II. With the circuit thus far described, when the line wires H and I! are energized, the motor-will run at substantially constant speed.

The contactor rocker arm II is connected by conductor I! to line wire H. One end of the coil II, as above explained, is connected to the end contact member 42, and the other end of the .coil is connected by conductor II to conductor II on the motor side of the field winding I so that the coil '2 will be shunting the field winding I of the motor 4. A switch I. is preferably included in the conductor 11 to selectively cut in the control device II when the operation of the device is deemed necessary.

In operation, the present fuel supply system together with my novel pump speed control device operates very rapidly, accurately, and efllciently. Let it be assumed that the engine II is being supplied with fuel fromthe tank I solely by the fuel pump 1 and condition vary to a point such that the fuel pump I is not pressuring the fuel sufficiently. The booster pump 8 may then be cut in in series with the fuel pump 1 to build up the pressure by closing the circuit through line wires II and II. The booster pump. operating at constant low pressure speed in series with fuel pump 1, is ordinarily sufficient to properly pressure the fuel through all the upper altitudes.

However, if there is a partial or complete failure of the engine fuel pump, then it is essential that the booster pump do emergency work and operate at a higher speed sufiicient to maintain a satisfactory pressure differential over the carburetor. The switch ll may then be closed by the pilot or operator cutting in the automatic speed control device I I. As long as the pressure differential over the carburetor is satisfactory with the operation of the booster pump at constant low pressure 'speed, the contactor rocker arm I! will be restlng 'on the contact member 42 so that substantially all of the coil 52 will be in circuit, and the speed of the pump will not 'be altered. when there is a change in that Dres- 'sure differential requiring the booster pump to operate at a higher speed, that change in pressure dinerential will be communicated to the control device ll through the pipes if and It. If thepreasurcbuildsupthroughpipe iI,thedlaphragms 2| and 21 within the casing would be moved upwardly carrying the shaft II therewith, and thus rotating the contactor rocker arm I! downwardly so that it flnally rests against one of the other contact members Ii to II inclusive, thus cutting out a part of the coil l2, and causing the current to seek the path of least resistance and shunt itself around the field circuit l of the motor, thus increasing the speed of the motor.

It will be appreciated that numerous increments may be provided in the coil '2, with a contact member for each increment, so that as the pressure differential over the carburetor fluctuates, the rocker arm 83 will rock backward and forward cutting out more of the coil I! or cutting in more of the coil 52 as the case may be, and maintaining the proper speed of the booster pump motor at all times so that the proper pressure differential is maintained over the carburetor to an extremely fine and accurate degree. The entire failure of the fuel pump I will not interfere with adequate operation of the fuel suppl system, because the entire load will then be transferred to the booster pump and the speed of this pump is automatically regulated at all times as above described so that the proper pressure of fluid to the carburetor is maintained.

It will, of course, be understood that in the construction of my automatic speed control device, insulating bushings and insulation connections oi various kinds may be used between the respective parts to avoid the described circuit from being unintentionally grounded at any points in the structure. It will likewise be understood that control switch means may be incorporated at any desired point in order to energizeand de-energize either the main circuit or the auxiliary circuit from the automatic control device.

From the foregoing, it is apparent that I have provided a novel fuel supp y system in which a series of fuel pumps may be incorporated, and pressured fuel supplied to a carburetor under predetermined conditions of all kinds. It will he noted that the pressure diii'erential between the carburetor intake and the carburetor discharge to an internal combustion engine is maintained constant by pressure responsive means, regardless of whether-only one or all of the pumps are operated. Further, it will be noted that the speed control device for a pump, embodied in this invention, is accurate to a very fine degree, and exceedingly positive in its action, in that little if any arcing will result from 'a circuitcloaing operation and positive pressure is exercised in a direction through the point of contact at all times. Moreover, the entire structure is not only highly efficient in use, but economical to install and operate.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

seasons I claim as my invention:

1. In a pressure responsive control device, a casing,a diaphragm across said casing. a fluid conducting pipe connected to said casing on one side of said diaphragm, variable resistance means. a rocker arm selector associated with said resistance means to close a circuit through various resistance increments, means connecting the rocker arm to said diaphragm to be actuated thereby, said casing having an opening therein on the opposite side of said diaphragm from said pipe, and toggle mechanism connecting said diaphragm with said rocker arm to actuate the latter, and maintain the same pressure on the rocker arm regardless of the point of contact with said resistance means.

2. In a fluid pressure responsive control device, a casing, a pair of spaced diaphragms across said casing, means connecting said diaphragm to cause operation in unison, a fluid conducting pipe connected to said casing on the outer side of one diaphragm, another fluid conductin pipe from a different source connected to laid casing on the outer side of the other diaphragm, a variable ruistance, a selector associated with said resistance, and means connected with said diaphragms therebetween and extending through the casing wall to actuate said selector to close a circuit through various increments of said w sistance in keeping with variations of pressure in said pipes.

3. In a fluid responsive control device. a casing. a pair of spaced diaphragms across said casing, means connecting said diaphragms to cause operation in unison, a fluid conducting pipe connected to said casing on the outer side of one diaphragm, another fluid conducting pipe from a diiferent source connected to said casing onthe outer side ofthe other diaphragm, a variable resistance including a rocker arm selector, said casing having an opening therein between said diaphragms, and toggle means connecting the diaphragm; with the rocker-arm selector to actuate the latter in keeping with variations in fluidpressureinsaidpipes andmaintainequal pressureonthe selectorresardlessofthspointof contact with said resistance.

4. In a control device, a resistance element, a

series of contact members each connected to said element at a different point therealong. a rocker-arm selector. rockable over said series of con-.

tact members to close a circuit throuah increments of said element, means to actuate said rocker-arm, flxed means adjacent said contact members, a spring holder voted to said fixed means,aspringinsaidho er,ayoke attached to said rocker-arm selector and enclosing said spring holder and against which said spring bears,

-apinonsaidyokeextendingintosaidspting holder and the spring therein to cause said holder to pivot with a movement of said rocker-arm selectorandmaintainthespringpressureonsaid yokeinadirectionthroughthepointofoontact betweensaid selector and one of said contact members at all times.

Rm R. CURTIS.

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