Patent Publication Number: US-4370107-A

Title: Spring biased fluid pump

Description:
TECHNICAL FIELD 
     The present invention is directed to fluid pumps and, more particularly, to intermittently energized fluid pumps capable of producing a relatively sustained average high pressure output even at relatively low flow rates. 
     BACKGROUND OF PRIOR ART 
     Intermittent input, average output types of pumps, also known as impulse pumps, have been known. Such pumps may have a movable pumping member that is moved to one position to load fluid into a pumping chamber and to another position to pump fluid from such pumping chamber. The loading action may occur in response to an intermittent work input, such as one derived using a solenoid and an electrical energy input, and the work output or pumping action may be effected by a spring or other work or energy storage device into which work (energy) had been stored during energization of, for example, the solenoid. Typically the solenoid core is connected to a pumping diaphragm to draw fluid into the pumping chamber during energization of the solenoid in a suction stroke. 
     Various types of mechanical check valve arrangements have been used in the past to control the flow of fluid, vis-a-vis such prior pumps. Also, a movable contact arrangement was necessary to effect intermittent energization of the solenoid. 
     Some disadvantages encountered in the prior pumps of the subject type have been fluid leakage due to the multiple complex elements utilized and the relatively high cost also for the same reason. Furthermore, undesirable energy dissipation may occur in the prior pumps where the contact alignment is not maintained constant during multiple operations; accordingly, the contacts often become prematurely worn due to arcing and/or uneven current flow during multiple uses. Additionally, due to the frequent use of separate pump diaphragms, sealing gaskets, sealing measures taken at the check valves, etc., not only are the leakage and cost affected substantially, but the labor required to manufacture such prior pumps becomes excessive and expensive. Furthermore, with the actuator, such as the solenoid core directly connected to the pumping diaphragm, the drag produced by the latter during the suction stroke wastes energy of energization of the solenoid and reduces stroke distance of the core and, thus, the fluid capacity of the pump. 
     BRIEF SUMMARY OF INVENTION 
     In accordance with the present invention, a fluid pump is provided having a fluid inlet and outlet, a pumping chamber, inlet and outlet check valves, respectively, for passing fluid in a single direction from the inlet to the pumping chamber and from the latter to the outlet and for blocking fluid flow in the opposite directions, and pumping means for drawing fluid from the fluid inlet via the inlet check valve into the pumping chamber and for pumping fluid from the pumping chamber via the outlet check valve to the fluid outlet. Preferably an energy or work storage device, such as a spring, effects a substantially constant pumping pressure on fluid in the pumping chamber except durng the brief time that an actuator causes the input of energy or work into such storage device and preferably the simultaneous drawing of fluid into the pumping chamber. 
     In accordance with a principal aspect of the invention an energy storage means provides a work input to the pumping means both to draw fluid into the pumping chamber and to pump fluid therefrom and a power means intermittently supplies work for storage as potential energy in the energy storage means. 
     In accordance with one aspect of the invention at least one of the inlet and outlet check valves comprises a self-sealing check valve assembly formed by first and second relatively rigid members, each having a plate-like surface facing the other with a fluid passage opening at such surface and bounded by boundary portions of the surface, a flexible means positioned between the plate-like surfaces for cooperating with the boundary portions to provide a substantially fluid-tight seal therewith, and the flexible member including a movable portion for moving upon flexure of the flexible member in response to a pressure differential across the latter, the movable portion including a means operative when the flexible member is moved substantially to its opposite extreme positions to block fluid flow between the fluid passages and to permit such fluid flow, respectively. 
     In accordance with another aspect of the invention such flexible member is just one part of an overall flexible member that provides a flexible portion for the other check valve, a flexible portion as a pumping diaphragm, and a remaining portion for providing a gasket-type fluid sealing function. 
     In accordance with an additional aspect of the invention, an improved carrier assembly, particularly intended to carry a movable contact for movement intermittently to energize the pumping means, is provided. Such carrier includes a curved arm having a tendency to assume a natural condition when at least substantially unstressed, having a resilient characteristic operative generally in a direction at least approximately perpendicular to that in which a radius of curvature of the curved arm is taken, and having a pair of ends, one end being relatively fixedly supportable and the other being relatively movable with respect to the one end, and a means for applying force to such other end in a direction at least approximately parallel to that in which such resilient characteristic is generally operative causing resilient deformation of the curved arm to cause movement of such other end with respect to such one end. The curved arm has a tendency to reassume its natural condition when not having been stressed beyond its elastic limit by such force and such force is removed and due to its length, say in a flat plane, can undergo substantial distance of movement of the movable end without exceeding its elastic limit, thus increasing the possible input and output stroke distance of the pumping mechanism. Several advantages inure to the carrier, including, for example, repeatability of movement of the movable contact supported thereby, the maintaining of the movable contact in a single plane over a relatively large movement distance proximate a relatively fixed contact, thereby allowing the contact surfaces to be relatively planar to provide a relatively large surface area connection therebetween for optimum current flow characteristics therebetween. 
     With the foregoing in mind, a principal object of the invention is to provide a pump that is improved in the noted respects. 
     Other principal objects include the reducing of energy wasting and stroke limiting (pump capacity) caused by drag during the suction stroke. 
     Another object is to minimize the power requirements of a pump. 
     An additional object is to provide longevity for a pump. 
     A further object is to minimize leakage from a pump. 
     Still another object is to provide a relatively high pressure output over a relatively wide range of flow rates, including a relatively low flow rate, from a pump as well as to provide a well balanced or averaged output from an impulse type pump. 
     Still an additional object is to provide an improved check valve. 
     Still a further object is to provide a resilient carrier assembly, especially for an electrical contact, with relatively accurate motion repeatability characteristics. 
     Even another object is to minimize the cost for a pump, including the labor and materials costs. 
     These and other objects and advantages of the invention will become more apparent as the following description proceeds. 
     To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described in the specification and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various ways in which the principles of the invention may be employed. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     In the annexed drawings: 
     FIG. 1 is a front elevation view of a fluid pump in accordance with the present invention; 
     FIG. 2 is a bottom plan view of the pump of FIG. 1; 
     FIG. 3 is an upright section view of the pump looking generally in the direction of the arrows 3--3 of FIG. 2; 
     FIG. 4 is a top view of the pump looking generally in the direction of the arrows 4--4 of FIG. 3 but with the top of the pump case removed to show the contact carrier assembly; 
     FIG. 5 is a bottom plan view of the rigid bobbin and plate-like surface thereof looking generally in the direction of the arrows 5--5 of FIG. 3; 
     FIG. 6 is a top plan view of the flexible member looking generally in the direction of the arrows 6--6 of FIG. 3; and 
     FIG. 7 is a top plan view of the bottom cover plate looking generally in the direction of the arrows 7--7 of FIG. 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now in detail to the drawings, wherein like reference numerals designate like parts in the several figures, and initially to FIGS. 1 and 2, a fluid pump in accordance with the present invention is generally indicated at 1. The pump 1 includes an exterior shell 2 formed by the multiple parts exteriorly visible, and a mounting bracket 3 fastened to the pump by screws 4, 5 in holes 4a, 5a seen in the several parts shown in the other figures to facilitate mounting the pump 1 to external support means, not shown. A fluid inlet 6 and a fluid outlet 7 of conventional design protrude from the shell 2 for facile attachment to hoses or the like in conventional manner for providing fluid from an external supply, not shown, to the inlet 6 and conducting pumped fluid from the outlet 7 to other equipment, not shown, for use thereat. 
     The shell 2 is formed by external walls of a hollow case or cover 8, a cylinder-like wall 9 of a bobbin 10, a flexible member 13, and a rigid bottom cover plate 14. Preferably the case 8, bottom plate 14, and mounting bracket 3 are electrically conductive and are connected in electrical common by the screws 4, 5 to provide a ground circuit path for an actuator located within the pump 1, such actuator being of the type that produces output work in response to an electrical input. Moreover, in the preferred embodiment and best mode of the invention, such actuator is a solenoid; accordingly, the bobbin 10 preferably is of electrically non-conductive material to provide a proper support for the solenoid windings within the pump 1. The flexible member 13 preferably is of Neoprene material or like material that has satisfactory flexibility and resiliency for providng gaskettype fluid sealing function, check valve function, and pumping function, as will be described further below. A further screw 15 in holes 15a, and still other ones, not shown, if desired, provide additional fastening force to secure the various portions of the fluid pump 1 as an integral structure. 
     Turning now particularly to FIGS. 2-7, fundamentally the pump 1 includes, in addition to the inlet and outlet 6, 7, an inlet check valve 20, an outlet check valve 21, a pumping chamber 22, a pumping mechanism 23 for drawing fluid from the inlet 6 and via the inlet check valve 20 into the pumping chamber 22 and for pumping fluid from the latter via the outlet check valve 21 to the outlet 7, and an energy controlling mechanism 24 to control input of energy to the pumping mechanism 23. 
     As is seen in FIG. 3, the lower flange 30 of the bobbin 10 has a larger radial thickness than the upper flange 31, which fits within the case 8. The flange is substantially solid (except as shown and described further below), with a central passage 32, fluid inlet and outlet passages 33, 34 leading and fluidically connected to the respective fluid inlet and outlet 6, 7, a rigid plate-like bottom surface 35, inlet check valve inlet flow path 36 (leading from the passage 33 to open at the surface 35), and outlet check valve outlet chamber 37 (also opening at the surface 35 and leading to the fluid outlet passage 34). Wrapped around the relatively narrow mid portion of the bobbin 10 between the flanges 30, 31 is a plurality of conductor turns generally designated 40 forming the electromagnetic portion of a solenoid actuator that is energizable to provide a work input for the pump 1. 
     The bottom cover plate 14, which is seen most clearly in FIGS. 3 and 7, has a plate-like top surface 41 that preferably is rigid and flat like the plate-like bottom surface 35 of the bobbin flange 10 to mate in opposition with respect to the latter separated only by the flexible member 13. The bottom cover plate 4 has formed therein, for example by machining or during the molding or casting thereof, an inlet check valve outlet chamber 42 which opens to the surface 41, a loading flow passage 43, the pumping chamber 22, and an outlet check valve fluid inlet passage 44. It is the purpose of the loading flow passage 43 to load fluid drawn by the pumping mechanism 23 into the pumping chamber 22 from the inlet check valve 20. It is the purpose of the outlet check valve fluid inlet passage 44 to conduct fluid from the pumping chamber 22 to the outlet check valve 21 for delivery out to the fluid outlet 7. 
     The remaining fluidics portion of the pump 1, in addition to the lower flange 30 and cover plate 14 together with the flow passages and chamber therein, is the flexible member 13, which is cooperative with the plate-like surfaces 35, 41 and respective open areas therein to form the inlet and outlet check valves 20, 21. Moreover, the central area 50 of the upper flexible portion 11 provides a pumping diaphragm function. For that purpose the central area 50 is substantially integral or solid and is urged by a spring 51 into engagement with the iron core 52 or other movable member of the pump actuator, in the illustrated preferred embodiment a solenoid 53, preferably without otherwise being secured to such movable member. Therefore, as the core 52 moves upward in the bobbin central passage 32 under the electromagnetic force created by the energized turns 40, the central area 50, which preferably has a resilient characteristic to facilitate deformation thereof, also is moved up by work provided by the spring 51 to draw fluid into the pumping chamber 22. Similarly, when the core 52 is moved downward, the central area 50 pumps fluid from the pumping chamber 22 and work is stored in the spring 51 as potential energy ready for the next suction cycle. Moreover, preferably the flexible member 13 has a resilient characteristic to facilitate its being urged into fluid-tight sealed engagement with the respective bottom and top surfaces 35, 41 where they form boundaries about the central passage opening 32 in the former and the pumping chamber 22 in the latter. Preferably the spring 51 is located in the pumping chamber 22 and bumps or nubs 13a on the flexible member 13 may provide a centering or guiding function for the spring 51 with respect to such member. 
     The preferred flexible member 13 is formed of a single molded piece of Neoprene material having a pair of relatively large circular recesses 66, 67, solid areas 62, 65, holes 61, 63, and central area 50. The hole 61, solid area 62 and recess 66 operate in the inlet check valve, whereby the solid area 62 may block fluid flow from the inlet check valve inlet flow path 36 into the inlet check valve outlet chamber 42 during pumping and the solid area 62 flexes into the recess 66 during the re-loading or drawing of fluid into the pumping chamber 22, thereby allowing fluid flow through the holes 61. The holes 63, solid area 65, and recess 67 operate similarly, vis-a-vis the outlet check valve fluid inlet passage 44 and outlet check valve outlet chamber 37 of the outlet check valve 21, to pass fluid to the fluid outlet during pumping and to block reverse fluid flow during the re-loading half cycle. Further details of the check valves are disclosed in copending, concurrently filed, and commonly assigned U.S. patent application Ser. No. 109,547, of Paul R. Goudy, Jr., entitled &#34;Fluid Pump,&#34; the disclosure of which is hereby incorporated by reference. 
     One lead 70 of the conductor forming the turns 40 of the solenoid 53 is threaded through an opening in the lower flange 30 of the bobbin 10 and is directed outward of the pump 1 for connection to a source of electrical power. The other lead 71, which is shown in FIG. 4, is connected intermittently via the energy controlling mechanism 24 also to such source of electrical power, not shown, to complete a circuit for the solenoid 53. A spring 72 provides a biasing force on an electrically non-conductive and nonmagnetically responsive plunger 73, for example of nylon, which has an enlarged slug-like cylinder portion 74 positioned in the central passage 32 in engagement with the iron core 52, tending to urge the core 52 and, thus, the central area pumping diaphragm 50 into the pumping chamber 22 to pump fluid therein. For that purpose, the lower end of the core 52 engaged with the central area 50 is beveled at 75 to facilitate a gradual generally uniform deformation of the central area 50 during such pumping. 
     The spring 72 also tends to urge a movable electrical contact 76 toward the position shown in phantom to engage a relatively fixed electrical contact 77 in order to complete an electrical circuit for the solenoid 53. Upon such circuit completion, the energized solenoid draws the iron core 52 upward, whereupon the pumping mechanism 23 draws fluid into the pumping chamber 22. As the core 52 moves upward, the upper surface 78 of the sluglike plunger portion 74 separates the contacts 76, 77 de-energizing the solenoid 53. The overall momentum of the core 52 and plunger 73 tends to move the same a maximum stroke distance to store a maximum amount of work as potential energy in the spring 72 preferably until the upper surface 78 achieves a position approximately aligned with the lower surface 79 of a contact carrier assembly 80 to be described in greater detail below. 
     Furthermore, during the energization stroke of the actuator, which is also the suction stroke of the pump 1 to draw fluid into the pumping chamber 22, the movable member of the actuator moves substantially independently of the pumping diaphragm area 50. It is the spring 51 that urges the area 50 upward to cause a suction head in the pumping chamber 22 drawing fluid in from the inlet check valve 20 and closing the outlet check valve 21. Since the strongest force output of the solenoid 53 ordinarily occurs at the instant of energization, the total magnitude, or nearly so, of that output can be converted to work for storage in the spring 72 with desirably a maximum travel of the actuator movable member occurring. Thus, efficient energy usage is made. Additionally, since the suction head is produced preferably substantially linearly by the spring 51, rather than by the energy surging actuator, an initial surge in suction is reduced or totally eliminated thereby to optimize operation of the inlet check valve and to minimize energy dissipation in the flowing fluid. 
     Thus, it will be appreciated that it is the force and, accordingly, the work input, provided by the spring 72 that effects a substantially constant pumping pressure on the fluid in the pumping chamber 22 during the pumping cycle of the fluid pump 1. If the force constant of the spring 72 is substantially linear, then the fluid pressure of the pumped fluid will remain substantially constant during the pumping cycle even over a relatively long period of time if the flow rate out of the fluid outlet 7 is relatively small. The time required for reloading the pumping chamber 22 during upward movement of the core 52 ordinarily will be relatively short and, therefore, preferably will not have a substantial effect on the average pressure of the pumped fluid and this is especially true if the total stroke distance of the solenoid, core 52, plunger 73, pumping diaphragm area 50 and spring 72 of the pumping mechanism 23 is maximized. Such stroke distance, of course, is a function of the permissible relative travel distance of the contacts 76, 77. Furthermore, it will be appreciated that it is most desirable that the fluid pumped by the fluid pump 1 is of an incompressible type, such as water, in order to optimize pump operation. However, it is possible that compressible fluids also may be pumped, although overall pumping efficiency may be reduced. 
     Moreover, in view of the foregoing, it will be appreciated that the actuator which provides a work input to the fluid pump 1 and in the preferred embodiment preferably is of the electromagnetic type, such as the solenoid 53, only is intermittently energized to store energy in the spring 72, thus minimizing the overall power input requirements of the fluid pump 1. The spring 72, on the other hand, assures a substantially uniform pumping output from the fluid pump 1. If desired, other types of actuators, preferably of the intermittently energizable type, which produce output work in response to an energy input may be substituted for the solenoid actuator 53. During a pumping stroke some of the energy stored in spring 72 is transferred to the spring via the plunger 73 and core 52 as well as by the flexible member 13. Of course, preferably the spring force constant of the spring 51 is much smaller than that of the spring 72. However, in the preferred embodiment the parameters of the spring 51, spring 72, solenoid actuator 53, core 52 and plunger 73 are selected such that the collision force occurring between the pumping diaphragm central area 50 and the bottom of the core 52 at the end of a suction stroke is minimized. 
     Additionally, it is believed that the pump 1 has advantages over that disclosed in the mentioned copending application because more effective use of the core and plunger momentum may be had, operation may be at a greater frequency, and higher fluid pressures may be produced. 
     The energy controlling mechanism 24 includes the contacts 76, 77, the contact carrier assembly 80, a fixed contact support 81 to which both the fixed contact 77 and lead 71 are electrically and mechanically connected, and an electrically non-conductive pedestal 82 for mounting the carrier assembly 80 spaced away from the upper surface 83 of the bobbin upper flange 31 and, of course, spaced away from the fixed contact 77 and its support 81. The fixed contact support 81 as well as the contact carrier assembly 80 may be formed of copper, brass, or other electrically conductive material. A screw 84 holds the carrier assembly 80 to the pedestal 82, secures the latter against the fixed contact support 81 holding the same in relatively fixed position engaged with the upper surface 83 of the flange 31, and passes in electrically insulated isolation through an opening in the fixed contact support 81 for securement in the upper flange 31. The screw 84 also preferably secures a completed circuit for a capacitor 85 to the carrier assembly 80. Such capacitor 85 also is electrically connected to the fixed contact support 81 in order to provide an arc suppressing function, vis-a-vis the contacts 76, 77 in conventional manner. 
     Turning now in detail to the contact carrier assembly 80, it is the purpose of such assembly to enable efficient electrical connections to be made between the movable and fixed contacts 76, 77, on the one hand, and an assured periodic interruption of such electrical connections, on the other hand, with a minimum of work effort required to effect the same. It is also desirable to maximize the movement distance and the repeatability of movement of the movable contact so that a relatively maximum surface area of the latter will engage a relatively maximum surface area of the fixed contact, thus providing efficient current carrying capability therebetween with minimum energy dissipation; this being in contrast to conventional contacts having predominantly point contact connections particularly in those instances that at least one of a pair of contacts is curved or spherical to accommodate possible differences in the cyclical movements of the contact pair. 
     To accomplish the foregoing and additional advantages mentioned below, it is desirable that the carrier arm 90 of the contact carrier assembly 80 have an adequate resiliency in the direction of usual movement, i.e. perpendicular to the direction of varying radius of curvature thereof, to assure periodic separation of the contacts and to enable periodic connection of the contacts with a minimum work effort required to effect the same. Moreover, to fit the carrier arm 90 within the confines of the fluid pump 1 while still maintaining the relatively long length thereof for optimum resiliency and, yet, relatively minimum force constant characteristics, the carrier arm 90 is curved in a polar or circumferential direction about the longitudinal central axis of the pump 1, as is seen most clearly in FIG. 4. One end 91 of the curved carrier arm 90 is fixed or secured by the screw 84 to the pedestal 82 and in electrical connection via a conventional electrical connector 92 with the capacitor 85. The other movable end 93 of the carrier arm 90 has the movable contact 76 attached thereto. A force applying arm 94 attached to and preferably integral with the movable end 93 extends radially inwardly toward the axial center 95 of the pump 1, and a force input end 96 integral with the arm 94 is circularly enlarged with respect to the latter to receive input force by the bottom end of the spring 72 engaged with the top surface thereof and by the upper surface 78 of the enlarged plunger portion 74 engaged with the bottom surface thereof and to accommodate the narrower upstanding rod-like portion of the plunger 73 in a central opening formed within such end 96. Upstanding tabs 97 integral with the circular end 96 hold the bottom portion of the spring 72 in position with respect to the contact carrier assembly 80 and a recess 98 in the top of the pump case 8 holds the upper end of the spring in the position shown in FIG. 3. 
     Although not shown as such in FIG. 3 for clarity of illustration, it will be appreciated that ordinarily the upper surface 78 of the enlarged plunger portion 74 will be engaged with the botton surface of the circular force input end 96 of the arm 94. Moreover, the iron core 52 and bottom surface of the enlarged plunger portion 74 also preferably ordinarily will remain in mechanical engagement with each other. Therefore, when the solenoid actuator 53 has been energized upon a closure of the contacts 76, 77, and the pumping mechanism 23, including the central area 50, iron core 52, plunger 73, movable carrier arm end 93, force input end 96, and spring 72, will be forced initially by the work input of the solenoid actuator 53 and subsequently by momentum of the pumping mechanism 23 upward until the movable contact 76 has reached a relatively maximum spacing away from the fixed contact 77. Thereafter, with the solenoid actuator 53 deenergized, the spring 72 urges the remaining parts of the pumping mechanism 23 in a downward direction to pump fluid, as described above, while applying a force in a direction approximately parallel to the resiliency characteristic of the curved carrier arm 90 tending to move the movable end 93 thereof and, thus, the movable contact 76, toward the fixed contact 77; the next energization cycle occurs upon the touching of the contacts. If desired, the contacts 76, 77 themselves may be eliminated with simply the surfaces of the fixed contact support 81 and movable carrier arm 90 providing for electrical contact therebetween; nevertheless, for optimum efficiency and longevity it is desired to use the illustrated contacts. 
     Furthermore, in accordance with the preferred embodiment of the invention the contact carrier assembly 80 is formed of a flat disc-like member cut to the shape illustrated in FIGS. 3 and 4. The spring force constant of the force applying arm 94 preferably is appreciably greater than that of the curved carrier arm 90; this being accomplished, for example, by making the radial width of the arm 90 relatively thin and the width of arm 94 relatively large. Therefore, as the spring 72 and force applying arm 94 apply force in a vertical direction, i.e. into the plane of the paper relative to FIG. 4, to the movable end 93, there will be relatively little bending or torquing of the latter as it moves downward from the planar natural unstressed condition shown in FIG. 3. Moreover, due to the high level of resiliency, length, and relatively small spring force constant of the curved carrier arm 90, the latter may be moved repeatably over many cycles long distances without deformation of the same beyond its elastic limits without substantial fatigue and without substantial bending of the end 93 out of a plane parallel to its natural flat plane. Preferably the plane in which the arm 94 is naturally positioned, e.g. when it, as an integral part of the contact carrier assembly 80, and the latter assume a flat or coplanar configuration when unstressed, and those in which the arm 94 pass during movement are substantially parallel with each other and with that of the contact surfaces of the contacts 76, 77; and preferably the plane in which the spring 72 and arm 94 interact and particularly in which the former applies force to the latter also is parallel to the aforesaid planes. Moreover, in view of the foregoing and since there is relatively little torquing of the curved arm 90 or pitching or yawing of contact 76, the actual movements of the movable contact are repeatable with a high degree of accuracy, and as a result there will be minimum wear on the contacts and optimum electrical connection efficiency between the contacts. 
     The capacitor 85 in conventional manner facilitates opening the contacts especially without arcing. The one piece contact carrier assembly 80 improves the operational efficiency of the pump 1 by eliminating any mechanical interconnections of contact supports, thereby eliminating a source of possible wear and failure. 
     As was mentioned above, one end of the conductor forming the turns 40 of the solenoid 53 is connected via lead 70 to a source of electrical power. The other end is connected via lead 71 and intermittently via the contacts 76, 77, when closed, contact carrier assembly 80, spring 72, and pump case 8 to the opposite polarity connection of such source of electrical energy. The preferred orientation for the pump 1 is in vertical direction as illustrated in FIG. 1 to avoid possibility of fluid leakage from the fluidics part below into the electrical part above. 
     Summarizing operation of the fluid pump 1, then, ordinarily the spring 72 urges the contacts 76, 77 to a closed condition and upon such closure of the contacts 76, 77, the energized solenoid 53 will drive the pumping mechanism 23, including the core 52 and plunger 73, while spring 51 urges the pumping diaphragm area 50 upward to effect a suction in the pumping chamber 22 drawing fluid from the fluid inlet 6 via the inlet check valve 20 into the pumping chamber 22 while the outlet check valve 21 remains closed. Thereafter, the spring 72 causes the pumping mechanism 23 to pump fluid out the outlet check valve to the fluid outlet 7 while the inlet check valve 20 remains closed and energy is stored in spring 51. It will be appreciated that since the check valves operate only on differential pressure and not on the basis of any external mechanical means, such as additional springs, ball seals, or the like, the amount of energy dissipated thereat and required to operate the same is minimized while the overall longevity thereof is maximized.