US2322913A - Pump - Google Patents

Description

June 29, 1943. F Q BEST ETAL 2,322,913

PUMP

. Filed April 22. 1939 2 Sheets-Sheet l .Elg l zdA . *T6-ck Lawler I ,lvebrs Han/l agent will be referred to later.

threaded fitting 26 of ferrous material, and sealed by a gasket 28. Between the.threaded fitting 26 and the piston assembly I2 is a coil spring 82 which normally forces the piston assembly"l2 upwardly, where it is restricted in movement`by a coil spring 84 secured to an end fitting 24 of non-ferrous material, the latter being threaded into the upper end of the cylinder I8, and the joint sealed by a gasket 28. Near the upper end of the tube I8, its outside surface is knurled to insure adhesion of a plastic housing 46 for the pump control mechanism, this housing being molded around the tube I8 in manufacturing. Surrounding the lower portion of the tube I8 is an electrical solenoid 48 enclosed in a ferrous housing 58, the latter two parts being held in position between the lower portion of the housing 46 and the lower threaded fitting 28. In the upper interior of the housing 46 is located a permanent U shaped magnet 52 in horizontal position, its poles engaging extensions 56. These extensions 66 are pressed into holes in the wall of the tube I8, their inner surfaces being flush with the internal surface of the tube I8, and their upper edges 68 being substantially in line with the top surface I8 of the upper piston I8 of the piston assembly I2 when the latter is in its upper position. A semi-circular armature 64 of ferrous material is located in the plane of the magnet 62 and partially surrounds the cylinder I8, the ends of the armature being adjacent to the poles of the magnet 62. The armature 64 is secured to a stamping 66 which is pivoted on a pin 58, and which carries at the end opposite from the pivot an electrical contact 88. This contact is normally maintained in engagement with a mating contact 82 (secured in the housing 46) by a coil spring 86 mounted upon and guided by a pin 64 secured inthe housing 48. The housing 48 also encloses an electrical condenser 18 which A nonferrous cover 68 maintains the magnet 62 in position and is re.- tained in place by the upper threaded fitting 24.

In Figure '7, electrical'current flows from a. battery 88 (or any other suitable source of electricity) through the ignition switch 82 to the movable stamping 68 associated with the armature 64. The contact 88 on the stamping 68, when engaged with the fixed contact 62. completes an electrical circuit allowing current to flow through tlie solenoid coil 48.

In Figure 3, the pump 84 is installed in a motor car 14, close to the tank 18 from which the pump 84 draws fuel by suction through a tube 88 and a filter 82 when in operation. Fuel from the pump 84 is then forced under pressure through the tube 88 to the carburetor 88.

When the ignition switch 82 in Figure 7 is,

closed, electrical current flowing through the solenoid coil 48 attracts the lower piston I4 (constructed of ferrous material) of the piston assembly I2 and pulls the latter downward, overcoming the force of the spring 82. When the piston. assembly I2 moves downward, pressure in the lower chamber I8 beneath the piston maintains a disc type one way inlet valve 86 in a closed position against a valve seat 88 and forces the fluid contents of chamber I8 through the piston assembly I2, passsing through a disc type one way transfer valve 28 located in the upper piston I8 of the piston assembly I2, (the valve 28 be ing restrained from excessive movement by a retainer 22 pressed into the upper piston I8) and filling the upper chamber I6. Movement of the valve 28 is also assisted by inertia. As the upper piston I8. of ferrous material, travels downward, the magnetic flux between the permanent magnet 62 and the upper piston I8 (through the medium of the extensions 55 of the poles of the magnet 62) becomes gradually reduced while the flux between the magnet 52 and the armature 64 (of ferrous material) gradually increases. At a pre-determined point in the downward travel of the piston, near the end of its stroke, a condition is reached, as illustrated in Figures 4 and 4ta-wherein the attraction of the magnet 62 for the armature l64 becomes sufficient to overcome the force of the armature spring 66. The armature 64 and its support 66 then move toward the magnet 62, pivoting on the pin 68 and. carrying the contact point 68 out of engagement with the fixed contact 82. A pin 5l on the armature supn port 66 is provided to contact the end of the pin 64 in order to prevent the armature 54 from corning -into contact with the poles of the magnet 52f When the circuit is broken between the contact points 68 and 62, the pull of the solenoid 48 is released, but the piston assembly I2 still continues a short distance beyond this point due to inertia. When the circuit is broken, the action of the condenser 18 dampens the spark across the contact points 68 and 62 and thus the life oi' these points is prolonged. The pumping spring 32 then starts to push the piston assembly I2 upward, thus forcing the fluid in the upper chamber I5 out through the upper fitting 24, the pressure present and inertia tending to hold the transfer valve 28 on its seat in the upper piston I8. Simultaneously, a partial vacuum created under the piston assembly I2 in the lower chamber I3 induces the entry of liquid through the fittings 44 and 26, and past the one way valve 86 into the chamber I3. As the piston assembly I2 continues upward, the magnetic flux between the upper. piston I8 and the permanent magnet 62. through the medium of the extensions 55 of the poles of the magnet 62, increases, while the flux between the magnet 62 and the armature 64 decreases. At a pre-determined point in the upward travel of the piston assembly I2, near the end of its stroke, a condition is reached as illustrated in Figures 5 and 5a. wherein the magnetic attraction acting on the armature 64 is no longer sufficient to hold the spring 86 in compression, and the latter then forces the armature 54 and its support 66 away from the poles of the magnet 62, the armature and its support rotating on pin 58 and carrying the movable contact 88 into engagement with the fixed contact 82, thus closlng the circuit. The piston then continues slightly beyond this point, due to inertia, and comes to rest against bumper spring 84, the latter attached to end fitting 24 and utilized to absorb shock and reduce noise. The circuit being now closed, another cycle of pump operation starts.

It will be observed, by referring to Figures 4. 4a, 5 and afthat the critical piston position at which the contact points start to open during downward piston travel, is lower than the critical piston position at which the pointe start to close during upward piston travel. As a magnetic force increases inversely as the square of the distance, it will be readily apparent that the mag- Y 2,322,913 Anetic. flux requiredto pll the armature I toward the magnet 52, overcoming the force of the armalture return spring 86, will necessarily be greater than the magnetic fiux required to hold the arma- `ture close to the magnet while maintaining the spring under compression. A's the fiux of the magnet 52 is constant, it will be seen that the relationship of the piston I8 to the magnet 52 will determine the number of lines of magnetic force shunted through the piston I8 and the number of remaining lines of magnetic force available at the magnet 52 for influencing the It will be noted that the upper piston I8 has been reduced in diameter at its upper end 2I and is guided in the cylinder I8 by its lower end of slightly larger diameter 2:#`

in order to avoid physical contact with theA extensions 55 of the poles of the magnet 52, thereby eliminating frictional drag at this point while still maintaining close relationship.

Figure 6 is a graph illustrating the effect of' piston position on the turning moments controlling the position of the movable contact point. It will be readily observed from this graph and the foregoing explanation of operating principles that there exists a very definite and prolonged lag in'contact point movement in relation to piston travel. This lag is further increased by the effects of inertia and friction. As a result, the stroke of the pump is longer compared with present practice and the number of operating cycles per minute can therefore be reduced for a given output per minute. This latter feature contributes to a greatly increased life of the piston and cylinder, valves, operating spring, contact points, condenser, and solenoid; in short, the entire pump. It will be readily apparent from all of the foregoing description that the pumping element of this device is completely sealed against leakage, and that neither the solenoid nor breaker mechanism comes in contact with the fuel, thus eliminating fire hazard.

By the use of this construction, a piston pumping element may be employed without danger of external leakage, thus eliminating the necessity .of using flexible bellows or diaphragms with vtheir attendant short life, unreliability, and contribution Yto re hazard.

Because of the fact .that the velocity of the piston on the pumping stroke is dependent on the rate of fuel flow between the piston and the carburetor and because the piston must complete a full pumping stroke before starting another cycle of operation, the pump operating cycle frequency is dependent o n the fuel requirements of the engine. As the piston on its downward or charging stroke always moves with the same velocity regardless of the fuel consumption rateV of the engine, the electrical energy expended during the charging stroke is substantially constant. However, it is obvious that the rate of current consumption will vary with the number of pumping cycles for a given time period, thus, the current consumption rate will vary in proporticm to the rate of fuel consumption of the engine.

Due to the fact that this pump is 'of the long stroke, slow speed type compared to existing commercial designs, pumping pressure will be more uniform throughout its operating range and there will be less tendency for` the pumping pressuretovaryathigherenginespeedaasisnow the case with conventional short stroke, high speed, diaphragm or bellows Wpc Pumps- It will be seen in Figure 1 that the piston assembly I2 is composed of a lower piston I I of ferrous material and an upper piston I8 of like material joined together by a tube I5 of nonferrous material. This preferred construction is utilized for two reasons, first, in order to confine the effects of the magnetic field of the solenoid 48 solely to the lower piston Il by insulating the upperpiston I8 from tlese effects in order to avoid magnetic interference with the magnetically controlled and' actuated contact mechanism, and second, in order to facilitate priming. In the event of running out of fuel, a car equipped with this pump may' be left standing for a considerable period of time before refilling of the fuel tankwith the assurance that efiicient pumping action will start immediately, when the pump is put into operation. This is accomplished in the following manner: During the normal operation I4 and I8 becomes filled with fuel by the normal slight leakage past the pistons Il and I8. It Will be apparent to those skilled in this art that this slight leakage will besuilicient to supply the required small amount of fuel to this space or trap Il. In the event that the tank Supply becomes exhausted and the supply tubing and pump cylinder become emptied of fuel, the fuel in the reservoir I1 is still retained, and this fuel will act as a piston sealing means, thus assuring adequate pump suction in drawing fuel from the tank to the pump when the supply in the former is replenished.

It has been found that directly after a motor car has been left standingwith the motor stopped, that the fuel in the tubing between the pump and the carburetor will be subjected to residual heat dissipated by the engine, and will therefore expand. Due to the check valve in the pump, it cannot, return to the supply tank and therefore suilcientpressure is created to force the carburetor reservoir float controlled inlet valve olf its seat and by so doing, flooding of the carburetor and inlet manifold results. Starting `of the engine is'seriously impaired by this condition. This is prevented in the proposed pump by the provision of a pressure relief valve which will allow fuel in the process of expansion in the tube 88 in Figure 3 to iiow back to the supply tank 'I8 whenever the pressure in the tubing 88 reaches a point somewhat less than the critical pressure required to force the carburetor reservoir float controlledinlet valve off its seat. In Figure l, -the movable valve seat 38 of the inlet valve 36 is normally held in position by a spring 40, thus allowing passage of fuel only in one direction, that is, upwardly through the inlet valve 36 during no"mal pump' operation. In the event of fuel expansion previously described taking place, the high pressure in the tube will force fuel,v by leakage, past the piston assembly I2, and the pressure acting upon the area of the valve 38- and the uncovered area of its movable seat 38 will cause the latter to move downwardly, overcoming the resistance of the spring 48 and allowing the return of fuel between the edge of In any pump wherein the direction of fuel flow is changed due to the relationship of the pumping element to the inlet and outlet valves, a certain amount of energy must be expended in order to overcome the inertia of the fuel. In the proposed device, there is no change of flow direction under normal operating conditions, the fuel entering the pump at one end, passing through the piston and being discharged at the other end. This uni-directional, straight through, iiow condition reduces the amountof electrical energy expended for a given amount of fuel displaced, as compared to most conventional pumps.

It will be apparent from the foregoing description that the proposed device will not cause excessive heating of the fuel, as is experienced with some types of electrical pumps in which the solenoid and contact points are immersed in the fuel with consequent direct transfer of heat from these units to the fuel. As a result, vapor lock possiybilities from this source are considerably reduced in the present pump.

It will be easily seen from the description and attached drawings that fabrication of the device will not be costly. Assembly is simple, use being made of the end fittings 24 and 26 in Figure 1 to retain all of the parts in position.- A wire 30, passing through holes in the end fittings, and having its ends joined by an identifiable lead seal discourages tampering with the device, thus protecting dealers in these pumps when they are sold on a guaranteed basis.

It will be readily apparent, to one experienced in the art, that in connection with the above description, various equivalents or alternative materials, details, or the like may be employed. For example, ferrous material is intended to incl-ude all suitable magnetically permeable materials, non-ferrous material (when specifically referred to as such in the description) is intendedv to'include all suitable materials which are nonpermeable, plastic may include hard rubber or the like, the piston assembly l2 could be replaced by a one piece piston of ferrous material in which a high reluctance path between the lower and upper ends of the piston may be provided by considerably reducing the diameter of the piston betweenthesaid ends, the magnet 52 could be a continuously acting .electro-magnet, etc.

We claim:

l. An electromagnetic fuel pump comprising a relatively lon'g non-ferrous and completely sealed and thin walled cylindrical tube, a pumping piston having iron portions and reciprocating in said tube, means to reciprocate said piston including a solenoid about said tube actingon certain of said iron portions, and means to control the periodic energization of said solenoid in accordance with piston position and including a compact generally U-shaped permanent magnet having its two inner pole forming ends on either side of and in contact with said tube Walls, said magnet being within and adjacent one end of the piston's stroke so that fiux between the magnet's poles is periodically shunted across said tube by certain of said piston's iron portions, a fixed contact and a movable contact connected in circuit with said solenoid, a generally semi-circular shaped iron armature of relatively large cross-- sectional area to provide a low reluctance flux path movably mounted to have its ends attracted toward said magnets pole ends and carrying said movable contact, said generally U-shaped magnet and said generally semi-circular shaped armature together substantially and closely surrounding said tube, and spring means to move said armature away from said magnet.

2. An electromagnetic fuel pump comprising a non-ferrous cylinder having openings through the sides thereof, an iron pumping piston reciprocating therein, means to reciprocate said piston including a solenoid about said cylinder and relatively movable contacts in circuit therewith, and means to control the periodic energization of said solenoid in accordance with piston position and including a continuously acting magnet positioned within and adjacent to one end of the piston stroke and having its opposite poles on either side of, exten .ling through, and tightly fitting in said cylinder openings so that the inner faces of said pole ,extensions substantially form portions of the inner surface of said cylinder providing a low reluctance shunt path through said iron piston, and a movable resiliently biased armature actuating said contacts and attracted by said magnets poles when said poles are not shunted by the piston.

3. An electromagnetic fuel pump comprising a non-ferrous cylinder having openings through either side thereof, an iron pumping piston reciprocating therein with a substantially sealing working fit, means to reciprocate said piston includinga solenoid about said cylinder and relatively movable contacts in circuit therewith, and means to control the periodic energization of said solenoid in accordance with piston position and including a continuously acting magnet positioned within and adjacent to one end of the piston stroke and having its opposite poles on either side of, extending through, and tightly fitting in said cylinder openings so that the inner faces of said pole extensions substantially form portions of Vthe inner surface of said cylinder to give a low reluctance shunt path through said iron piston, and Ya movable resiliently biased armature attracted by said magnets poles, and actuating said contacts, said piston having an end portion of reduced diameter adjacent said pole extensions to avoid undue friction at these points.

4. In an internal combustion engine fuel supply system, a fuel supply tank, a fuel pump drawing fuel by suction therefrom and including a cylinder, a carburetor supplied with fuel under pressure by said pump, a fuel line between said pump and said carburetor, a pumping piston in said pump cylinder permitting a slight leakage therepast, valve means in said piston and cylinder to restrict fuel flow to one direction and a pressure relief valve between the suction side of said piston and the said supply tank, said valve permitting a relief discharge into said tank from the vapor pressure built up in said line when idland heated by 'said yslight leakage past said piston.

5. The organization set forth in claim 4in which said pressure relief valve constitutes a resiliently biased valve seat for one of said one direction valve means.

6. In an electrically operated pump, a cylinder, a pumping element in said cylinder, a molded housing secured midway on said cylinder, a removable inlet connection at one end of said cylinder', a solenoid about said cylinder and secured between said body and said inlet connection, a solenoid controlling breaker mechanism including a permanent magnet housed in said housing, a removable discharge connection at the other end of said cylinder, a cover for said housing secured in place by said discharge connection, and holes in both said connections and a wire extending therethrough and having its ends Iioined by an' 7. In an electrically operated pump, a cylinder,

a pumping element in said cylinder, a molded housing secured to said cylinder between the ends thereof, a removable inlet connection at one end' 8. Av wholly sealed solenoid fuel pump comprising an imperi'orate cylinder threaded at each end, an iron piston therein, a pipe fitting threadedly secured to one end of said cylinder,y a piston actuating solenoid positioned around said cylinder and held in one direction of axial movement by Nsaid iitting, a piston position controlled switch mechanism and a support therefor positioned around said cylinder and held in one direction of axial movement by said solenoid, and another pipe :fitting threadedly secured to the other'end of said cylinder and holding said support, against movementin the other axial direction.

FRANK C. BEST.h JACK A. LAWLER.

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