US2488384A - Fluid pump - Google Patents

Description

Nov. 15, 1949 J. w. DICKEY ET AL FLUID PUMP Filed Feb. 11, 1946 Nov. 15, 1949 J. w. DICKEY ETAL FLUID PUMP 3 Sheets-Sheet 2 Filed Feb. 11, 1946 7 d 4 4 A x BY jy'fzqvmzu Nov. 15, 1949 J. w. DICKEY ET AL 2,438,334

FLUID PUMP Filed Feb. 11, 1946 5 Sheets-Sheet 3 qwer INVENTORJ y 4m WITNESS. W 5 m. 9751 w 1%FYA Patented Nov. 15, 1949 FLUID PUMP John W. Dickey and Millard M. Henry, Elmira, N. Y., assignors to Bendix Aviation Corporation, Elmira Heights, N. Y., a corporation of Delaware Application February 11, 1946, Serial No. 646,951

3 Claims.

The present invention relates to electromagnetic motors and more particularly to motors for magnetically actuating pumps which are especially adapted for lifting liquid fuel from a storage tank to a consuming device such as an internal combustion engine.

In both automotive and stationary equipment powered by internal combustion engines it is the prevailing practice to supply fuel to the engine carburetor by means of a pump which is driven from some moving part of the engine. As the volatility of the fuel has increased, difiiculty with bubbles or vapor lock in the tubing between the supply tank and pump has been encountered, which difiiculty is aggravated as the length of the fuel line is increased and operating temperatures raised as in some commercial automotive and bus installations. To cure this difficulty it has been proposed to use electrically operated pumps which may be located remote from the engine, but those types of such pumps which have previously been offered to the public have been comparatively expensive in construction, and noisy and inefficient in operation.

It is an object of the present invention to provide a novel electrically actuated fluid pump which is efficient and quiet in operation while being simple and economical in construction.

It is another object to provide such a device which automatically maintains a substantially constant discharge pressure irrespective of variations the volume of fluid delivered.

It is a further object to provide such a device in which the stroke of the pump is maintained substantially constant, the volume of discharge being regulated by varying the frequency of operation of the pump.

It is another object to provide such a device in which the pump with its operating and controlling means is formed as a small unit which is entirely self-contained and may conveniently be positioned in any location where suitable electrical power is available.

It is another object to provide such a device in which the pump piston is actuated in its discharge stroke by a spring, and electromagnetic means are provided for retracting the piston and thereby storing up energy in the spring.

It is another object to provide such a device in which the electromagnetic retracting means is which the motion of the piston in its discharge stroke is arrested by the flux of the electroma net, while the retrograde motion of the piston is arrested by the spring after deenergization of the electromagnet.

Another object is to provide such a device in which the contacts which control the electromagnet are actuated by a magnet, the effective flux of which is varied by the approach and recession of the pump piston.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a vertical substantially mid-sectional view of a preferred embodiment of the invention, the electrical circuit therefor being shown diagrammatically;

Fig. 2 is a section taken substantially on the line 22 of Fig. 1;

Fig. 3 is a section taken substantially on the line 33 of Fig. 1;

Fig. 4 is a detail in perspective of the thrust member which supports the lower end of the operating spring;

Fig. 5 is a side elevation, partly broken away and in section of a second embodiment of the invention;

Fig. 6 is a section taken substantially on the line 66 of Fig. 5, and showing diagrammatically the electrical circuit for operating the device;

Fig. 7 is a detail in perspective of the circuit controlling device illustrated in Figs. 5 and 6;

Fig. 8 is a diagrammatic illustration of a modification of the electrical operating circuit of the Fig. 9 is an enlarged top plan view partly in section of a concentric form of actuating mechanism for the pump controlling contacts;

Fig. 10 is a sectional detail taken substantially on the line lfil 0 of Fig. 9; and

Fig. 11 is a graph illustrating the variations of flux in the contact controlling mechanism of Figs. 9 and 10.

In Fig. l of the drawing, there is illustrated a pump comprising a cylinder 1 in the form of a thin-walled tube of non-magnetic material such as brass or stainless steel, and a hollow tubular piston 12 formed of magnetic material such as soft iron slidably mounted in the cylinder with a free working lit. The lower end of the cylinder I is pressed into the neck portion 3 of a casing A which is also formed of magnetic material and extends upwardly for approximately the length of the piston 2, and is flared outwardly as shown at to form a seat for a second cup-shaped casing member 6 of magnetic material having a downwardly extending sleeve portion I closely surrounding the cylinder I.

A cap member 8 is arranged to form a closure for the casing member 6 on which it is pressed, and is also arranged to closely surround the upper end of the cylinder I. The pump cylinder and the parts of the casing described are preferably united and sealed in any suitable manner as by soldering or brazing the joints in order to provide a permanently closed fluid-tight casing surrounding the cylinder.

A hollow strainer fitting 9 is threaded on the neck 3 of the casing member 4 and is provided with a circumferential recess II which is covered by a strainer I2 retained against a shoulder II) on the fitting by a lock ring I3. Openings I4 connect the recess I I with the hollow interior I5 of the fitting into which the lower end of the cylinder I projects. A check valve I6 is arranged to bear on an annular shoulder I! in the interior of the fitting 9 and is normally held on its seat by a valve spring I8 which is retained by a perforated thimble I9 having a flange 2| which is clamped by the fitting 9 against the lower end of the cylinder I. A thrust plate 22 (Fig. 4) having slots 23 formed therein to provide free passage of the fluid to be pumped rests on top of the thimble I9. Plate 22 has upstanding lugs 24 which act as centering means for a spring 25 which bears at its lower end on the thrust plate and traverses the hollow piston 2, bearing at its upper end on a shoulder 26 formed therein. The spring thus tends to raise the piston and thereby discharge liquid from the cylinder.

A second check valve 21 is seated on an annular shoulder 28 formed on the top of the piston 2, and is pressed against its seat by a valve spring 29 which is maintained under compression by a perforated thimble 3| the lower edge of which is crimped into an annular recess 32 near the top of the piston. A threaded nipple 33 is pressed and soldered or brazed in the top of the cylinder I, and thereby provides means 4 by suitable means such as a cap screw 36 which is threaded into the strainer fitting 9, suitable gaskets 31 and 38 being provided to prevent leakage. A threaded flange 39 is formed on the chamber 35 for the reception of an inlet conduit M and a baflle 42 is preferably attached to the inner wall of the chamber in order to deflect the incoming fluid downwardly and rotarily for the purpose of facilitating the separation of sediment or water from the fuel.

Means for retracting the piston 2 at the end of its discharge stroke and thus storing energy in the spring for the next discharge stroke is provided in the form of an electro-magnetlc coil 43 surrounding the cylinder I and piston 2 and forming with the casing members 4 and 6 an electromagnet which when energized draws the lead 5I to one terminal of the coil 43, the opposite terminal of which is connected by a lead 52 to a contact 53 which is fixedly mounted in a cylindrical capsule 54 but insulated therefrom as indicated at A cooperating contact 5'6 is mounted on a cylindrical slug of magnetic material 58 which is slidably mounted in the capsule 54 and normally separated from fixed contact 53 by means of a spring 59.

The capsule 54 is formed of electrically conductive non-magnetic material such as brass or copper and is grounded so that the contact 56 is also grounded as indicated diagrammatically at 6| and thereby completes the circuit for the coil 43 when the contacts 55 and 53 are in engagement.

Means under the control of the piston 2 for closing said contacts when the piston approaches the end of its discharge stroke are provided comprising a coil 82 which surrounds the capsule 54 and is seated on the bottom of the cup-shaped casing member 6 which thereby provides the lower pole piece of the electro-magnet formed by said coil. An upper pole piece 533 of magnetic material is seated on the upper end of the coil 52 and has openings adapted to fit the capsule 54 and the cylinder I to which it may be united in any suitable manner.

The coil 62 is connected at one end by a lead 69 to the binding post 48, and the other end of the coil is connected to the ground 6! by a lead 65 whereby the coil 52 is energized continuously when the switch 47 is closed.

It will be seen that there is an air gap as between the upper pole piece 63 and the lower pole piece, and the characteristics of the coil 62, the strength of the spring 59 and the dimensions of the slug 58 are so proportioned that the flux traversing the magnetic circuit of the coil 52 is insufiicient to hold the contacts closed when the gap 64 is open. When the piston i2 rises on its discharge stroke however, the upper end thereof bridges the gap 54, which reduces the reluctance of the magnetic circuit and consequently increases the flux sufliciently to cause the slug 58 to compress the spring 59 and close the contacts. Since it takes considerably less flux tohold the contacts closed than it took to close the contacts, the contacts will not open until the piston has been retracted substantially to the lower end of its stroke as shown in Fig. 1.

In certain installations, it may be preferred to incorporate an arrangement for deenergizing the coil 62 at the time that the main solenoid 43 is energized in order to provide a more positive means for opening the contacts 53, 56. This may readily be accomplished by connecting the lead 60 of the coil 52 to the lead 52 of the main solenoid 53. With such an arrangement, the coil 62 is so constituted as to have a comparatively high resistance such as ohms, while the main solenoid 43 has a low resistance such as 3 ohms. When the contacts 53, 58 are open, the coils are in series and the coil 62 is fully energized inasmuch as the resistance of the coil 43 is comparatively negligible. The coil 43 however is at this time deenergized since the small amount of current permitted to flow by the coil 62 is too small to have any substantial effect on the coil 43. When the contacts 53, 56 are closed however, the coil 43 is fully energized and retracts the piston 2, while coil 62 is short-circuited and deenergized, thus permitting contacts '53, 56 to open after a short time delay determined by the self-inductance of the coil 62 and the hysteresis of the magnetic circuit. This alternative structure is illustrated in Fig. 8 of the drawings.

In operation, closure of the switch :41, which is preferably the ignition switch of the engine to be operated, energizes th control coil 92. If the pump has not been recently operated, the piston 2 will probably be at the end of its discharge stroke, and the energization of coil 52 will immediately close contacts 53, 56 since the upper end of the piston 2 is bridging the gap between the pole pieces of said coil. Closure of contacts 53, 56 causes energization of the main solenoid coil 43 which attracts the piston 2 downwardly, compressing the spring 25. The piston 2 is thus withdrawn from the gap between the pole pieces of the control coil 92 whereupon the flux thereof becomes insufiioient to hold the contacts closed.

is attracted upwardly to cause contact 59 to engage contact '53, whereupon the operation is repeated.

The polarities of the solenoid coil 43 and the control coil 92 are preferably so related that energization of the solenoid 43 reinforces the flux I of coil 62. This arrangement increases the length of stroke of the piston 2, and reduces sparking at the contacts 53, 56.

It will be understood that during the downward stroke of the piston, the check valve I6 is held against its seat II, whereby the liquid in the cylinder I is displaced upwardly through the check valve 21. When the piston 2 moves upwardly, the check valve 21 closes and the liquid above the check valve is ejected from the pump through the discharge conduit 9A, while liquid is drawn into the lower end of the cylinder through the check valve Iii.

In the embodiment of the invention illustrated in Figs. 5, 6 and '7, the pump mechanism and its actuating means are the same as in the first embodiment, but a control mechanism incorporating a permanent magnet is employed in place of the electromagnetic control previously described. As here illustrated, a semi-cylindrical chamber or capsule II of non-magnetic material is located adjacent the upper end of the pump cylinder I and maintained in position by suitable means such as a sprin clip I2. A curved arm is is pivotally mounted in casing II as indicated at M, and carries on one end a contact which is grounded as indicated at I5. A fixed contact "II is mounted in the wall of the chamber II, insulated therefrom as shown at '58, and is connected by the lead 52 to one terminal of the solenoid coil 43, the other terminal of which is connected by the lead 5! to the binding post 48.

The arm 13 is a composite member comprising a portion 19 which is a permanent magnet, and a portion 8I of a non-magnetic material. A spring 82 is arranged to bear on the arm so as to Swing it about its pivot in a direction to hold the movable contact I5 spaced from the fixed contact 'I'I.

Capsule or chamber II is preferably filled with an inert gas such as nitrogen in order to prolong plied so that the pump may be automatically energized when the engine is placed in operation.

In the operation of this embodiment of the invention, when the piston 2 is at the bottom of its stroke as shown in Fig. 5, the spring 92 holds the contacts I5, '11 open, and the solenoid coil 43 is cle'energized. As the spring 25 raises th piston 2, the upper end of th piston forms a return path for the flux of the permanent magnet I9 whereby the magnet is drawn toward the piston, compressing the spring 82 and closing contacts "I5, H.

The coil 43 is thereby energized and draws the piston down, compressing the spring 25 until the top of the piston moves out of the fiux path of the permanent magnet E9. The spring 82 is thereby effective to open the contacts 15, TI and the spring 25 then actuates the piston to discharge fuel from the top of the cylinder I through the conduit 34.

In Figs. 9 and 10 of the drawing, there is illustrated a form of contact-controlling mechanism employing an electromagnetic coil which is arranged coaxially with the pump-actuating electro-magnet 43, and embodying means for accurately controlling the opening and closing of the control contacts so as to determine the length of the stroke of the pump. As best shown in Fig. 10, an electromagnetic coil 9|, corresponding in function to the coil 62 in Fig. 1 and similarly energized as by means of leads and 90, is arranged to surround the pump cylinder I adj acent the upper end of the stroke of the piston 2. A lower pole member 92 for said coil is pressed on the pump cylinder against the casing member 5 and carries a fixed contact 93 insulated there from as indicated at 94. An upper pole piece 95 is also pressed on the pump cylinder above the coil 9!, and an armature member 96 is mounted on the lower pole member 92 as indicated at 97 for pivotal movement toward and away from the upper pole piece 95. Armature 99 carries at its free end a movable contact 99 in position to engage the fixed contact 93. A spring 99 acting on the armature 96 tends to separate contacts 93, 98 against the flux of coil 9|, the degree of separation being limited by a stop member I00. It will be understood that contacts 93, 99 perform the same functions as contacts 59, 53 in Fig. 1.

In this embodiment of the invention, the flux circuit of the coil 9] includes a sleeve I9I of magnetic material such as soft iron located within said coil and forming a partial core therefor, but separated from the pole pieces 92, 95

by annular air gaps I92 and I93 which are thus in series in the flux circuit from pole to pole of coil 9|. The piston 2 as it rises in the cylinder under the action of the spring 25 thus bridges first the air gap I92 and then the air gap I03 also, in both cases producing a significant reduction in the reluctance in the magnetic circuit of coil 9| and thereby increasing its flux. The motion of the piston through the intermediate space within the iron sleeve IDI however is less eflective to change the flux of the coil since this space is already bridged by said sleeve. It will be understood that the gaps I 02 and I93 may be filled by any non-magnetic material such as copper or fibre if desired in order to form a smooth core for the coil 9 I.

The polarity of the contact-controlling coil 9I is preferably so related to that of the main pumpactuating coil 43 that energization of the coil 43 reinforces to some extent the flux of the control coil. The dimensions and relationships of the parts are preferably such that when the coil BI is continuously energized similarly to coil 62 in Fig. 1, and the piston 2 has risen so as to bridge the lower gap I02 and about one-half of the upper air gap I03, the flux through the magnetic circuit of coil 9| will be sufficient to attract the armature 96 against the action of the spring 99 and close contacts 98, 93. On the other hand, when the piston is lowered to a point where it uncovers the upper gap I03 and substantially one-half of the lower air gap I02, the flux falls to a value sufficiently low to release the armature 96 and open the contacts.

Fig. 11 illustrates by means of a graph the changes in flux intensity of the magnetic circuit of control coil 9| during the reciprocation of the pump plunger. Starting for instance at the point A where the plunger .has risen so as to cover about one-half of the upper air gap and the flux is sunicient to close contacts 98, 93, closure of the contacts energizes the main pump actuating coil 43 and thereby increases the flux in the magnetic circuit of coil 9i as indicated by the line AB. As the coil 43 pulls the plunger 2 downward, the flux decreases rapidly as shown by the line BC until the upper air gap is completely uncovered by the piston. Further downward movement of the piston under the action of coil 43 gradually reduces the flux as shown by the line CD until the piston begins to uncover the lower air gap at the point D. The flux again decreases rapidly as the lower air gap is uncovered as shown by the line DE until at the point E the contacts are permitted to open, thus deenergizing the coil 43 and causing the flux to drop to the point F. The piston is now raised by the spring 25 causing a rapid increase in flux to the point G where the lower air gap is bridged, and thereafter a gradual increase in flux to the point H where the piston begins to bridge the upper air gap. This causes a rapid increase in the flux to the point A where the flux has built up sufficiently to again close the contacts and repeat the operation of the pump. The use of the magnetic core sleeve llll with the gaps I02,

1 I03, which cooperate with the piston 2 to cause opening and closing of the contacts, thus accurately determines the effective stroke of the piston. I

Since the remaining elements of the pump are the same as previously described and operate as above set forth, no further description of this embodiment of the invention is deemed necessary.

Although certain embodiments of the invention have been shown and described in detail, it will be understood that other embodiments are possible and that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In an electrically actuated pump a cylinder, a hollow piston or" magnetic material slidable therein, a spring -lor moving the piston in one direction, an electromagnet surrounding the cylinder adapted when energized to move the piston in the opposite direction, and means for intermittently energizing the electromagnet to cause reciprocation of the piston, including a. pair of contacts, and controlling means therefor including a source of magnetic flux and a circuit for the flux including a pair of annular pole pieces surrounding the cylinder and spaced axially of the cylinder, a sleeve of magnetic material surrounding the cylinder between said pole pieces and spaced axially therefrom to provide a pair of annular air gaps arranged in series in said circuit, one of the contacts being carried by a movable armature adjacent a pole piece, said piston in its spring-actuated stroke being arranged to substantially close first one of said gaps, and then the other gap also.

2. An electrically actuated pump as set forth in claim 1 in which the operation of the contacts is controlled by the piston moving with relation to the air gaps whereby the rapid change in flux traversing the magnetic circuit caused by the opening and closing of said gaps causes opening and closing respectively of said contacts.

3. An electrically actuated pump as set forth in claim 1 in which the movement of the pump piston eliects a magnetic circuit such that when both gaps are substantially closed by the advance of the piston the contacts are caused to close, and when both gaps are opened by the retraction of the piston, the contacts are permitted to open.

JOHN W. DICKEY. MILLARD M. HENRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 458,873 Van Depoele Sept. 1, 1891 1,598,792 Wallace Sept. 7, 1926 1,615,139 Rusdell Jan. 18, 1927 1,640,741 Nallace Aug. 30, 1927 1,640,742 Wallace et a1. Aug. 30, 1927 1,690,348 Wallace Nov. 6, 1928 2,179,925 Dilg Nov. 14, 1939 2,322,913 Best et al. June 29, 1943 2,381,650 Dick Aug. 7, 1945

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