US2754436A - Electromagnetic operated fuel pump - Google Patents

Description

July 10, 1956 P. WARGO 2,754,436

ELECTROMAGNETIC OPERATED FUEL PUMP Filed Jan. 11. 1952 2 Sheets-Sheet 1 J/zfmw 7 21. 5,

July 10, 1956 P. WARGO ELECTROMAGNETIC OPERATED FUEL. PUMP 2 Sheets-Sheet 2 Filed Jan. 11, 1952 United States Patent ELECTROMAGNETIC OPERATED FUEL PUMP Peter Wargo, May wood, Ill., assignor to Stewart=Warner Corporation, Chicago, Ill., a corporation of Virginia Application January 11, 1952, Serial No. 265,975

4 Claims. (Cl. 31032) The present invention relates to electric pumps and more particularly to direct acting electric pumps of the direct current solenoid actuated type. Although pumps of this general character have various applications, they are particularly useful as fuel pumps for pumping gasoline, for instance, from the main tank to the carburetor float bowl of internal combustion engines. For this application a pump of this type has the desirable characteristic of pumping fuel to the carburetor only when fuel is needed; that is, the pump operates intermittently according to demand and keeps a substantially constant pressure on the fuel at the carburetor float bowl or other delivery point.

One of the objects of the present invention is to provide a novel, direct current electric pump of the direct acting type which is easy to service and which can be manufactured at relatively low cost.

Still another object is to provide an improved fuel pump having an extremely long and trouble-free service life as compared with pumps of this general category with which I am familiar.

Yet another object is to provide a novel direct acting electric fuel pump in which the complete valve assembly is easily removable for servicing and in which the pump electric contacts have an extremely long useful life.

Other objects and advantages will become apparent from the following description of a preferred embodiment of my invention.

In the drawings, which illustrate an automobile fuel pump embodying the invention and in which similar charactors of reference denote similar parts throughout the several views,

Fig. 1 is a side elevation of an electric pump embodying the features of the present invention;

Fig. 2 is a top view thereof;

Fig. 3 is an end view thereof;

Fig. 4 is a vertical longitudinal sectional view of the pump shown in Figs. 1 to 3;

Fig. 5 is a horizontal view looking downwardly at the motor portion of the pump and may be considered as taken in the direction of the arrows along the line 55 of Fig. 4 just beneath the top of the pump case; and

Fig. 6 is a right end view of the motor portion of the pump and may be considered as a transverse vertical sectional view taken in the direction of the arrows along the line 6-6 of Fig. 4.

Referring to the drawings, it will be seen that the pump proper is comprised of a casting 10 which is secured by means of screws 12 to a sheet metal motor case made up of a bottom dish-like portion 14 covered by a top closure member 16. As best seen in Figs. 1 and 3, the pump casting lltl is provided with a pair of pads 18 on each side, which are threaded as at 2% for attachment of the pump to a mounting bracket, it being appreciated that whether the mounting pads 18 on one side of the pump or those on the other are used will depend upon the particular automobile or other device upon which the pump is mounted.

2,754,436 Patented July 10, 1956 In Fig. 1 it will be seen that fuel enters the pump through a pipe or tube fitting 22 threaded into an opening 24 in the pump casting 1t; and that the fuel leaves the pump by way of a pipe or tube fitting 26 threaded into an outlet bushing 28. At the lowermost point in the pump casting a threaded cup 39 is fitted and serves to plug a clean-out opening and hold in place a cylindrical cup-shaped screen 32 within an inlet reservoir 34. This cup-shaped screen is maintained upwardly in sealing relation with a flange at the upper end of the reservoir 34 by means of a compression coil spring 36 disposed between the cap 3t) and the lower end of the screen 32. The reservoir 34 is so oriented that fuel entering the pump by way of the fitting 22 and opening 24 flows into the space in the reservoir 34 around the screen 32 and thence through the screen and upwardly through a drilled passage 33 which intersects a horizontally drilled passage tl leading to the inlet valve 42.

The inlet valve is of the flat disc type comprised of a generally circular disc 4 having notches at its edge to permit the flow of fluid past the disc. This disc seals against a machined valve seat formed in the casting 1d at the outlet end of the horizontal fluid passage The valve disc is held against this seat by a light coil compression spring 4-6 the opposite end of which surrounds and seats against a nose of reduced diameter at the end of a tubular extension which is included as a portion of an outlet valve seat forming member indicated generally by the numeral 43.

The outlet valve forming member 43 comprises a screw machine part which is generally tubular in nature and which has a cylindrical outer end portion of large dial. eter that slides within a cylindrical recess it formed at the outlet end of the pump in axial alignment with the inlet fluid passage ill. At its inner end the cylindrical recess 59 has a shoulder against which the inner end of th cylindrical sleeve 4-8 is seated with its outer end 52 substantially flush with a shoulder formed at the lower end of an axially aligned threaded recess 54 at the pump outlet. The inner end of the large portion 48 of the outlet valve forming member has a smaller opening formed therethrough of approximately the same size as the inlet passage 4% and the inner end surface of the large portion of the member 48 is machined to provide a valve seat for a valve disc 55. This second valve disc as may be exactly like the inlet valve, that is, it should be generally circular excepting that the edge should be serrated or otherwise interrupted to provide space for iluid to flow around the edge or" the valve disc when the valve is in open position. This outlet valve disc is maintained in position by a coil compression spring 58 baclred up by a cup-shaped retainer 63 which also has its outer edge substantially flush with the bottom of the threaded cavity 54. As previously mentioned, the right hand end portion of the valve forming member extends sufii ciently to the right to serve as a spring seat for the inlet valve spring This spring seat extension is generally tubular and has cross and end bores as which permit fluid to flow from the inlet valve to the outlet valve It should be noticed that with this arrangement t e inlet valve seat and the outlet valve seat are coaxial and that the parts are such that all of the valve elements can be inserted through the outlet end of the pump after which a rubber gasket 64 is inserted into the threaded recess 54 and retained in place by the threaded bushing 28 which when tightened acts to seal against leakage around the outer surface of the outlet valve forming member 43. Conversely, by removing the outlet bushing 28, all of the valve parts may be dumped out of the outlet opening of the pump, thus making servicing and replacement of parts extremely easy.

The upper face or" the casting 10 is fiat and has a shallow pump recess 63 formed therein which is closed by a flexible diaphragm 7t clamped in place between the top face of the casting 1t) and the lower surface of the motor housing 14. This pump recess or cavity 63 connects with the valve chamber at a point between the inlet and outlet valves by means of a vertical passage 72. The central portion of the pump diaphragm 7t? is clamped between a pair of washers 74 secured to the lower end of a pump stern as. This stern passes upwardly through a hatshaped stamping into the motor chamber. The stamping 78 is hat-shaped so as to give clearance for the pump washer 74- at the uppermost portion of the pump stroke and also provides space and a seat for a coil compression spring which surrounds the pump stem 76 and bears downwardly upon the uppermost of the washers 7 so as to bias the pump diaphragm in a downwardly direction.

With this construction, as the pump stem 76 is moved upwardly the outlet Valve will be maintained closed and the evacuation thus produced in the pump chamber will open the inlet valve against the pressure of its spring 46 thereby permitting fuel to flow inwardly through the tube fitting 22 and through the strainer 32 and into the pump chamber so as to fill the space beneath the diaphragm 70. Upon the downstroke of the pump stem 76 the inlet valve will be closed and the outlet valve will be forced open, thereby discharging the fluid within the pump chamber by way of the openings 74 and outlet valve into the outlet fitting 28 and thence to the delivery point. The characteristics of the pump motor are such that energization of the pump causes the stem 76 to be lifted to the top of its stroke, at which point the pump is deenergized, thereby permitting the spring 80 to return the stem 76 to its lowermost position, thereby discharging fluid to the point of use. When the stem 76 reaches the lowermost portion of its stroke the pump is again energized to raise the diaphragm and re-energize the pump Spring 8%. This action causes fluid to be delivered by the pump always under the influence of the spring 80 and thus the pressure of the fluid will be substantially constant and will be determined by the pressure exerting capacity of the spring 80 and the effective area of the diaphragm 70.

The motor for intermittently lifting the stem '76 is disposed within the generally rectangular case 14. The upper end of the lower portion 14 of this case is formed to provide a generally horizontal outwardly turned flange to which the cover is crimped at intervals with a rubber gasket 89 disposed between the two so as to seal the case. A channel, indicated by the numeral 82, is formed across the left hand end of the case portion 14 just inside the horizontal flange and extends along the side walls of the case approximately two-thirds of the distance toward the other end. This channel serves to provide space for laminations 83 which make up the motor frame and the magnetic circuit for a solenoid coil 84. As shown, this frame is comprised of three laminations which are generally U-shaped and lie in the before-mentioned channel 82 and which also provide a central post or core element 86 formed integrally therewith. This core element extends horizontally into the space provided for the motor a from the left hand end of the case. The bottom lamination and the intermediate one are of the same length, whereas the uppermost lamination is slightly shorter at its right hand end so as to provide a pair of ears 85 at the extreme right hand ends of the lower two laminations. A cross member 88 is secured at each end to the laminations by means of screws 90 threaded into these cars. The three laminations after being formed, are stacked as shown, and spot welded together so as to provide a rigid frame unit which can be handled easily. The previously wound solenoid coil 84 is slipped in an endwise direction over the central post 86 and is followed by a heavy copper disc 92 which is fitted over the pole and stacked so asto form a rigid assembly. This copper disc or washer serves an important function to be discussed presently in addition to acting as a securing element.

i The stack of laminations is retained in the groove or channel 82 by means of the rubber gasket Sit which also serves to seal the cover member 16 to the lower portion 14 of the motor case.

The armature of the device, indicated at 94, comprises stack of horizontal laminations secured together by rivets which also secure a rearwardly extending flat, stiff plate 36 near the center of the stack with a thin clock mber 93 immediately therebeneath. This he member extends to the right over a rved and inclined support plate 1% which at its rear d end is attached along with the clock springlilte member to the cross-member 3% by several rivets 102. The armature is therefore free to swing upwardly and downwardly by flexure of the spring-like member 98 with substantially no friction and is kept under control by the overlying stiff plate 96 which ends short of the cross member and the lower curved support member 100. The length of the armature longitudinally of the pump together with the length of the clock spring-like member, and the position of the crossmember $8 is such that the nose of the armature just clears the end of the central post 36 of the laminations. The armature nose is ground or otherwise shaped as shown so that it is preferably not an arc of a circle but rather such that at all positions of the armature the portion of the face opposite the pole piece inclines away from the pole piece at the top so that the pull upon the armature is always more nearly upwardly with their being considerably less of a longitudinal component tending to pull the armature horizontally toward the pole piece than is customary.

The armature has a centrally located generaly rectangular hole 1% extending therethrough from top to bottom through which the pump stem '76 passes. At each side of this hole the armature is slotted downwardly about half way from the top to form channels into which the ends of a short cross pin M7 fit. A portion of one of these channels is indicated at 1%. This cross pin extends through the pump stem 75 with its ends resting against the bottom ends of these channels so that upward movement of the armature will lift the cross pin 1%? and, therefore, the stem 76, whereas deenergization of the electromagnet 34 will permit the stem 76 to be pulled downwardly by the pump spring 80 thereby pulling the armature 94 along with it to the lowest point in the pump stroke.

The construction therefore is such that periodic energization of the solenoid 84 will cause the armature 94 to rise and fall, thereby actuating the pump. The contacts which actuate the solenoid are disposed at the right hand end of the device and comprise a pair of stationary contacts 168 connected in parallel by an electrically conductive strip which also has a tab 112 to which one of the leads from the electromagnet is soldered. The stationary contacts 108 are horizontally spaced with respect to each other and are carried upon an insulating strip 114 supported in a vertical position by a pair of bracket arms 116 formed as rearward and downward extensions of a strip 118 secured by screws 120 to the cross-member 83. The other lead from the solenoid 84 is soldered to an internal terminal 122 also carried by the insulating strip 114, this terminal in turn during final assembly being connected by a lead 124 to an outside terminal 126 to which electrical connection to the device is made. Although the terminal 126 may be connected in any suitable fashion to the battery of the vahicle, it is preferably connected through the engine ignition switch so that the pump is automatically turned otf and on along with the engine.

A pair of movable contacts 128 mate with the stationary contacts 108 and are carried at the ends of a conducting cross-member 130 secured at its center to the lower end of a downwardly extending arm 132 which is generally L-shaped; that is, it has a vertical portion which carries the contacts 128 integrally formed with a horizontal portion which extends toward a position slightly above the face of the pole 86 of the electromagnet. At a midpoint it has an upwardly-bent vertical tab 134 pivoted by a loose rivet to a similarly upwardly bent tab 138 formed as a portion of the cross-strip 88. Thus as the left hand end of the arm 132 is lowered and raised the arm will rock about the point established by the rivet so as to rock the movable contacts 128 into and out of engagement with the stationary contacts 108.

The horizontally-disposed portion of the arm 132 is in a position above the armature 94 and has a loose fitting hole punched therethrough in alignment with the pump stem 76 so that the upper end of this stem passes through this opening. In a position above the armature but below the arm 132 the stem 76 is reduced in diameter to provide a shoulder upon which a cup-shaped spring keeper 140 is supported. This spring keeper carries a lightweight coil compression spring 142 the upper end of which bears against the lower surface of the contact carrying arm 132 thereby tending to bias this arm upwardly. Upward movement, however, is restrained by a washer fitted over the top end of the stem 76 and retained in place by a nut 144 threaded to the stem. The contactcarrying member 132 is formed of magnetic material and extends somewhat to the left beyond the pump stem 76 and there is bent downwardly slightly to form a small tab 146 just above and in front of the end of the magnetic pole member 86. In order to insure good grounding of the contact carrying arm 132, it is connected by means of a pigtail lead 148 soldered or staked thereto at one end with its other end similarly connected directly to the bracket member 116 which in turn is connected to the frame. The pump mounting bracket as is customary is therefore the other pump electrical terminal.

The action of the pump is as follows: If it is assumed that the armature has been lifted so as to fill the pump chamber with fluid and that the pump stem 76 is now settling under the influence of the pump spring 80; with the left hand end of the contact carrying arm 132 held in its uppermost position by the coil spring 142 it will be apparent that eventually as the pump nears the lower end of its stroke the movable contacts 128 will be swung toward the right until they touch the stationary contacts 108. At the time the contacts are first closed, it will be appreciated that the pump system is substantially in balance, that is, the spring 80 is barely overcoming the resistance at the outlet of the pump and, therefore, the immediate eifect of current flowing through the coil 84 will be to tend to lift the armature slightly thereby breaking the contacts again. This activity is normally very troublesome in pumps of this sort but is overcome in the present instance by the close proximity of the left hand end of the contact carrying arm 132 to the magnetic pole 36 together with the fact that the arm 132 is formed of magnetic material and that the spring 142 is very light in action. The first slight surge of current through the coil 84 therefore attracts the left hand end of the arm 132 downwardly, thereby compressing the light spring 142 and urging the movable contacts tightly into engagement with the stationary contacts. As the armature 94 moves upwardly under the influence of the magnetic field due to full energization of the solenoid 84, the magnetic attraction holds the left hand end of the contact carrying arm downwardly and keeps the spring 142 compressed, thereby holding the contacts in engagement until the pump reaches the uppermost end of its stroke. At this point the spring 142 is fully compressed and the movable contacts 128 are finally slightly separated from the stationary contacts 108. This deenergizes the solenoid coil 184 and releases the magnetic attraction both from the armature 94 and from the left hand end 146 of the contact carrying arm 132. This permits the spring 142 immediately to throw the left hand end of the contact arm upwardly against the overlying washer, thereby bringing about full and complete separation of the pump contacts. Releasing the magnetic attraction on the armature 94 also permits the armature and the pump stem 76 to settle under the influence of the spring so as to deliver fuel from the pump outlet. When the pump stem 76 reaches the low point in the pump cycle, the contacts are again brought together and the cycle is repeated.

The copper ring 92 which retains the solenoid in place on the pole piece 86 also acts as a short circuited secondary or shading coil and greatly increases the life of the contacts. This is true because when the circuit is broken by separating the contacts, instead of the heavy inductance in the circuit drawing a direct current arc, which is very destructive to contacts, the presence of the single turn copper coil acts to produce an alternating current are of comparatively high frequency. Such an arc is much more quickly extinguished than a direct current are and in addition has the advantage of rapidly shifting the polarity at the contacts so that there is no tendency for metal to be taken from one set of contacts and deposited in needle points on the others. As a matter of fact, the slight amount of contact material removed under the influence of the alternating current are does not appear to be deposited upon the other contact points at all but rather dusts away and leaves the contacts always in comparatively smooth condition. In addition, the random effect to the alternating current are on successive breaks tends to cause the last point of break to move over the faces of the contacts to that the contacts wear evenly. Because the contact sets are in parallel, anything which contaminates one set and prevents their properly making circuit will not affect operation of the pump, since the other set will take over the full duty until mechanical scrubbing action eventually removes the contaminating substance and puts the first set back into operation. Also, as previously pointed out, the fact that the contacts are closed hard together and are separated quickly prevents the phenomenon known as frying which ordinarily is very troublesome in pumps of this general character at the time that the circuit is made, because of the tendency of the armature to rise slightly and separate the contacts as soon as the solenoid coil is energized. The shading coil also causes the pump to operate more smoothly and with less noise, since it prevents an abrupt build-up of flux in the coil at the instant the contacts close.

Inasmuch as each stroke of the pump takes place as soon as the diaphragm has dropped to a certain position in its stroke, it will be apparent that the frequency of operation of the pump is determined by the quantity of fuel which can be delivered at the carburetor for instance. The result is that if the pump receives vapor, such as occurs when the engine is started after the vehicle has run out of fuel and has had the tank refilled, or, as sometimes occurs when the engine is idling and fuel in the lines has an opportunity to vaporize, the loading on the pump is very slight, and thus the pump operates with extreme rapidity and quickly clears all of the vapor from the line.

As soon as liquid reaches the pump the swirling action mixes the bubbles with the liquid, thereby quickly clearing all vapor from the pump chamber and from around the valves. The cycling rate of the pump thereupon automatically decreases to that necessary to supply the amount of fuel required for functioning of the engine. It should be noted also that the pumping chamber is at the highest point in the liquid passage and that therefore a small amount of water in the gasoline which collects at the lowest portion of the pump or, more properly, within the cup 30 does not cause malfunctioning even it the water freezes.

Normally, of course, the cross pin 107 is at the lower ends of the slots 106 in the armature, since the spring 98 which supports the armature is stiff enough to bias the armature upwardly. Occasionally, however, when the pump is operating at an extremely rapid rate because of the presence of vapor therein, the cross pin 107 may have a tendency to jump out of the upper ends of the slots 106 and for this reason a small clip 150 is riveted to the top surface of the armature in such position that it can be bent downwardly so as to cover a portion of the upper end of one of the slots 106, thereby preventing the cross pin 107 from jumping out of the slots 1% even under the most violent operation of the pump armature.

From the above it will be seen that a liquid pump constructed according to the present invention is admirably suited for pumping fuel to the carburetor of an internal combustion engine since it is relatively simple in construction and can be manufactured by known production methods at low cost, and in addition has an extremely long and trouble-free life under ordinary service conditions Where it usually will be completely neglected.

Although a single embodiment of the invention has been described, it will be apparent that variations and substitutions may be made therein without departing from the scope of the invention which is to be measured by the accompanying claims.

I claim:

1. An electric pump motor comprising: a reciprocable element, a movable armature connected for reciprocating said element, an electromagnet for moving said armature in one direction when energized, spring means for moving said armature in the opposite direction when said electromagnet is deenergized, stationary and movable contact means connected for energizing said electromagnet when closed, an arm pivoted at a midpoint and having one end positioned close to said electromagnet, said one end including a portion of magnetic material adapted to be attracted by said electromagnet to rock said arm about said pivot, said movable contact means being attracted to the other end of said arm so as to be moved contact closing direction when said one end is attracted, means connecting said one end of said arm to said element to cause said arm to be moved in contact closing direction as said armature is moved under the influence of said spring means, and resilient means connected between said arm and said element for biasing said arm in contact opening direction with increased force as said armature is moved in said one direction.

2. A direct current electric pump motor comprising: a reciprocable element, a movable armature connected for reciprocating said element, an electromagnet for moving said armature in one direction when energized, spring means for moving said armature in the opposite direction when said electromagnet is deenergized, stationary and movable contact means connected for energizing said electromagnet when closed, an arm pivoted at a midpoint and having one end positioned close to said electromagnet, said one end including a portion of magnetic material adapted to be attracted by said electromagnet to rock said arm about said pivot, said movable contact means being attached to the other end of said arm so as to be moved in contact closing direction when said one end is attracted, means connecting said one end of said arm to said element to cause said arm to be moved in contact closing direction as said armature is moved under the influence of said spring means, resilient means connected between said arm and said element for biasing said arm in contact opening direction with increased force as said armature is moved in said one direction, and said electromagnet having a short-circuited secondary thereon to produce an alternating are at said contacts when said contacts are separated. a

3. An electric motor of the reciprocating type comprising a reciprocable element, a movable armature connected for reciprocating said element in one direction, an electrcms for moving said armature when energized, spring means for moving said element and said armature in the opposite direction when said electromagnet is deenergized, stationary and movable contact means connected for energizing said electromagnet when closed, a swingabie arm having a portion thereof formed of magnetic said portion being positioned close to said electromagnet so as to swing said arm when said erectromagnet is energized, said movable contact means being attached to said arm so as to be moved in contactclosing direction when said portion is moved under the influence of said electromagnet, means connecting said arm to said element to cause said arm to swing in contact closing direction as said armature is moved under the influence of said spring means, and resilient means connected between said arm and said element for biasing said arm in contact opening direction with increased force as said armature is moved under the influence or" said electromagnet.

4. A direct current electric pump motor comprising a reciprocable element, a movable armature connected for reciprocating said element, an electromagnet for moving said armature in one direction when energized, spring means for moving said armature in the opposite direction when said electromagnet is deenergized, stationary and movable contact means connected for energizing said electromagnet when closed, means connected to said element for closing said contacts when said armature approaches the end of its stroke under the influence of said spring, and for opening said contacts when said armature approaches said one end of its stroke, and said electromagnet having a short circuited secondary thereon of such proportions as to produce a high frequency, alternating current are at said contacts when said contacts are separated.

References 'Sited in the tile of this patent UNITED STATES PATENTS

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