Patent Publication Number: US-4321021-A

Title: Metering pump

Description:
This is a division of application Ser. No. 637,647, filed Dec. 4, 1975 now U.S. Pat. No. 4,189,285. 
    
    
     This invention relates to metering pumps of simplified design for handling various fluids from liquids to gases in relatively small quantities per stroke but capable of delivering large fluid volume when number of strokes multiplied, such stroke increase conveniently controlled by solenoid operator which is adaptable to either valved pilot use for pump operation or to directly actuate pump piston for a subsequent piston reciprocation and pumping of fluid at specific controlled pump capacity per stroke, thereby enabling simple means to positively move fluid from a source to a receiver without the use of motors representing state of the art in pumps of present design. 
     It has been difficult if not impossible to pump exact fluid quantities in metered amounts with equipment for pumping in existance simply because there is no pump design on the market capable of such function unless resorted to very complicated controls which mostly are in fact not only unneeded but in majority of cases are too costly. Therefore, the object of this invention is to provide simple means for pumping fluids in metered amounts by the use of commonly available solenoid operators comprising generally a ferritic plunger passing within electrically developed magnetic field of a copper coil of multiple turns surrounding such plunger and together with appropriate plunger spring allowing to move a pump piston axially within a pump housing for pumping through piston reciprocation therein. 
     Further object of the present invention is to overcome many of the above-mentioned deficiencies of the prior art lacking on simple solenoid, pilot or manual pump. 
     These and other objects and advantages of the invention will become more fully apparent from the following description and accompanying drawings. 
    
    
     IN THE DRAWINGS 
     FIG. 1 is a cross-section of a metering pump with integral check valve operated by a pilot solenoid, including a check valve in the fluid supply port, detachably mounted inside a housing side port. 
     FIG. 2 is a cross section of a metering pump with integral check valve operated directly by the solenoid plunger, including external check valve in fluid supply port as well as a manual override provision, opposite the solenoid operator. 
    
    
     As can be seen from FIG. 1, the metering pump consists of the following basic parts: 
     an elongated pump housing 1 with a central differential diameter bore 2 passing therethrough for slidably receiving appropriate piston therein, having an integral check valve seat 8 adjacent one housing ends, including at last two side ports; 
     an elongated piston assembly 19 with body of different diameters corresponding to the diameters of the differential diameter bore 2 for a sliding fit therein with a first large piston end having a head 20 with a seal 21 and comprising a pump actuating means at the first housing end, and with a second piston assembly end 22 with seal 23 which is small, inside the check valve seat 8 comprising integral check valve 9 adjacent the second housing end, including a detachable check valve 17 having a floater sealing member 18 therein in one of said side ports; 
     and an electrically energized solenoid operator 5 disposed at the first housing end so as to cause piston reciprocation with pumping when solenoid becomes electrically energized thereby creating appropriate magnetic field inside operator cavity 35 to selectively move a solenoid plunger 34 axially, disposed therein in an operating relationship with the piston assembly 19. 
     Pump housing 1 includes a first housing end 3 provided with a large opening 4 adaptable to be closed by the solenoid operator 5, and a second housing end 6 provided with a fluid discharge port 7 inside of which a small aperture 8 ideally serves as a seat for a slidably moving seal 23 of the integral check valve 9. A conical seat 40 of tapered bore portion 11 adjacent aperture 8 continues inwardly with small end started at aperture 8 while the other inward end of the cone terminates with base 12 comprising in fact a diameter of the adjacent inwardly passing cylindrical bore portion 13 which continues toward the first housing end 3 enlarging again at shoulder 14 to a larger bore portion 15 which ends at opening 4 shown to be threaded for securing the solenoid operator 5 therein. 
     A first side port 10 enters conical seat 40 of bore portion 11 to supply fluid for pumping at metered amounts when piston is reciprocated inside housing bore 2, and is hence provided with the detachable check valve 17 for a directional control of the fluid flow into and through the pump, secured permanently therein by way of mating threads 24. A second side port 16 permits a pilot fluid to enter valve housing bore portion 15 adjacent shoulder 14 for aiding pump operation in conjunction with the solenoid operator 5. 
     Piston assembly 19 including the first large diameter piston head 20 with seal 21 of sliding fit with bore portion 15 incorporates therein an end face 20-a facing plunger 34 inside cavity 35, and an undercut 31 opposite end face 20-a, adjacent seal 21. It further continues as an elongated piston portion 29 of the diameter slightly smaller than the diameter of the cylindrical bore portion 13 with a seal 28 of a close sliding fit therewith, adjacent shoulder 14, inside bore portion 13 to subsequently taper down on an angle identical to the angle of the tapered bore portion 11 as shown by 26 to a straight necked-down piston section 25 of length equivalent to the pump stroke, having a diameter substantially smaller than the aperture 8 to facilitate an unabstrated fluid passage through an annulus created therein when piston assembly is moved from the position shown in FIG. 1 to have tapered piston portion 26 engage the conical seat 40 of bore portion 11 so as to displace all fluid from a pump cavity 27 clearly visible in FIG. 1 when solenoid operator 5 becomes energized, and the pilot pressure entering annular space 30 created between bore portion 15 and piston portion 29 that maintains piston assembly 19 in the first position of FIG. 1 while acting over undercut 31, is allowed to enter solenoid cavity 35 by way of a pilot port 32 starting adjacent undercut 31 and exiting in the center of head protrusion 33 normally covered by plunger 34 until the solenoid operator becomes energized uncovering pilot port 32 to exhaust pressurized pilot fluid into cavity 35 for subsequent action over the end face 20-a and piston position change from that shown in FIG. 1 to the second pump actuated position wherein mating surfaces of piston taper 26 and of conical seat 40 of bore portion 11 meet in direct contact, in fact thereby reducing seat loading distributed over the entire surface of mating tapers and extending service life of such pumps. It is not to say that tapers 26 and 40 could not be made square and act as shoulders meeting each other to displace fluid from such pump if applicational requirements allow this, without departing from the scope and the spirit of this invention. 
     The solenoid operator 5 entering bore opening 4 at the first housing end 3 is permanently secured therein by way of externally threaded boss 36 with a counterbore 42 facing piston head 20 to accomodate solenoid plunger 34 held against piston protrusion 33 by a spring 41 in axial relationship so as to normally close central pilot port 32 when the position of pump assembly components is as shown in FIG. 1, identifying solenoid cavity 35 open to atmosphere by way of solenoid exhaust port 37 shown therein. When solenoid coil 38 becomes energized electrically, iron 39 becomes magnetic capable of pulling plunger 34 away from the piston head 20 to close atmospheric solenoid exhaust port 37 rendering cavity 35 under pressure which, as discussed before, acts over piston head 20 initiating piston reciprocation and pumping. When solenoid energization is however discontinued, the magnetic force disappears and the plunger returns back into the original position over the protrusion 33 as a result of the force of the compression spring 41, discontinuing supply of the pilot pressure via pilot port 32, thereby allowing instant pressure rise in annular space 30 to act over piston undercut 31 with a force large enough to return piston assembly back into original position shown in FIG. 1 for pump filling with new supply of fluid to be pumped, via check valve 17 with unabstrated flow passage therethrough. Only when piston assembly 19 is reciprocatingly moved to discharge fluid from pump cavity 27, the check valve 17 becomes automatically closed by the fluid pressure action over floater 18 while the check valve 9 opens for fluid discharge via port 7. 
     This solenoid-pilot operated pump of FIG. 1 provides most simple means for metering fluids pumped by the use of a pressurized pilot fluid entering annular space 30 via side port 16 to maintain piston head 20 against solenoid boss 36 and the seal 23 inside seat of aperture 8. Seals 23 and 28 spaced a distance apart insure that pump cavity 27 receives fluid supply via port 10 through check valve 17 until the solenoid becomes energized lifting plunger 34 and thereby uncovering piston port 32 to discharge pilot fluid into the solenoid cavity 35 acting, in effect with a mechanical advantage, over the piston end face 20-a with a force larger than the opposing undercut 31-force to shift piston assembly 19 from the position of FIG. 1 into pumping and thereby fluid displacement from pump cavity 27 via discharge port 7 until the tapered piston portion 26 is forced into its mating conical seat 40 for a complete fluid displacement therefrom while the check valve 17 closes to insure fluid metering for as long as the cycle repeats. The instant the solenoid operator is deenergized allowing solenoid cavity 35 to exhaust via port 37, the pressure force over the end face 20-h disappears when the plunger 34 covers up pilot port 32 stopping further supply of pilot fluid into the solenoid cavity 35, and the piston assembly 19 becomes automatically shifted back by undercut 31 force into the original position with pump cavity 27 ready to draw a new fluid supply to be discharged therefrom again in exact metered amount when the cycle repeats, or during piston reciprocation when the solenoid operator 5 gets cycled. 
     The pump shown in FIG. 2 in all respect is analogous to the pump shown in FIG. 1 except that there is no pilot fluid to help in the operation of the pump, with a mechanical advantage at that. But, it was established that many applications of various processes, in particular those packaged independently, can not get compressed air nor other pressurized fluid and therefore require other solution for pumping fluids in metered quantities, often in minute capacities and at rather low pressures. To cover a gap of such vital but non-existing pumps, the pump described while discussing design of FIG. 1 was modified and presented in design shown in FIG. 2. 
     As can be seen from FIG. 2, the metering pump directly operated by a solenoid operator consists of essentialy the same basic parts as the pump of FIG. 1, which are as follows: 
     an elongated pump housing 51 with a central differentail diameter bore 52 passing therethrough for slidably receiving appropriate piston therein having an integral check valve seat 58 substantially midway of the housing, including at least two side ports: 
     an elongated piston assembly 69 with body of different diameters corresponding to the diameters of the differential diameter bore 52 for a sliding fit therein with a first piston end 70 of reduced cross section elongated comprising a pump actuating means at the first housing end, and with a second piston assembly end 60 terminating externally with a palm button 63 while inwardly continuing with a large piston portion 61 which terminates with a taper 62 adjacent seal 64 and a necked down piston section 65 of length equivalent to the pump stroke, with seal 66 inside the check valve seat 58 comprising integral check valve 67 of pumping means at the second housing end, including an intermediate diameter piston portion 86 starting at shoulder 87 adjacent seal 66; 
     an an electrically energized solenoid operator 55 disposed at the first housing end so as to exert pull force large enough to pull the piston end 70 against solenoid iron 54 shown with shading ring 56 facing a solenoid cavity 57 and thereby change the position of the piston assembly 69 from that shown in FIG. 2 to cause piston reciprocation with pumping when a solenoid coil 59 becomes electrically cycled making or breaking electric contact of the coil to continue pulling or releasing the piston assembly 69 which returns automatically to the original position by the force of a compression spring 71 lodged between a piston shoulder 72 at the end of the first piston end 70 of reduced cross section and the counterbore shoulder 73 of the solenoid operator 55. 
     It should be noted that in case of emergency or for priming purposes, the pump of FIG. 2 can also be actuated manually, by the palm button 63 in lieu of solenoid operator, through a simple depression of piston assembly 69 against the spring 71 by hand with a force sufficient also to displace fluid accumulated in the pump chamber, a factor of great importance in many applications, and in particular in cases where electricity is scarce, although the use of such palm button may be considered optional. But so is the solenoid operator 55 which can be considered optional for applications designated to be manual. 
     Turning back to the description of the design of FIG. 2 and in particular to the housing bore 52, it is seen that housing 51 includes a first housing end 82 provided with an elongated bore portion 53 having at its mouth threads 53-a adaptable to receive a threaded boss 74 of the solenoid operator 55 and passing inwardly partway toward the second housing end, and a second housing end 75 provided with a large opening 76 having an inwardly passing straight bore section 77 toward the first housing end including a conical seat 78 starting with cone base 79 at the end of straight bore section 77 and tapering down toward the integral check valve seat 58 which in fact represents the smallest diameter of bore 52 however of relatively short length as it again increases in the diameter immediately at a bore shoulder 80 to an intermediate diameter bore portion 81 which is larger than the check valve seat 58, continuing toward the first housing end until it meets with bore portion 53, including an internal groove 83 with a seal 84 at a shoulder 85 joining bore portions 53 with 81 of different diameters. 
     With piston assembly 69 inside the housing bore 52, the first piston position illustrated in FIG. 2 shows clearly that the shoulder 87 of piston assembly 69 is resting against the bore shoulder 80 as a result of the force of the compression spring 71 thereby cutting off the fluid communication not only between a side port 68 provided with an inlet check valve 17 with a floater 18 situated therein to feed pump chamber 88 and a side port 89 serving as a pump discharge means but also between the side port 89 and the solenoid cavity 57 both protected by seals 66 and 84. 
     Consequently, the pump chamber 88 of FIG. 2 created between the conical bore seat 78 and the piston taper 62 being open to draw fluid to be pumped via check valve 17 is, at the pump exit port of integral check valve 67, protected by a seal 66 inside seat 58. As soon as the solenoid operator 55 becomes electrically energized, the position of piston assembly 69 changes tending to eliminate the pump chamber 88 by having mating piston taper 62 of an angle identical to the angle of the conical bore seat 78 bottom each other displacing all fluid therefrom for a discharge through the side port 89 until the solenoid operator becomes deenergized at which time spring 71 will return piston assembly 69 back into original position shown in FIG. 2. 
     As can be seen from the description above the solenoid operated pump is indeed very simple and performs a pumping function in accordance with the objectives of this invention. 
     This invention is not restricted to the slavish imitation of each and every one of the details and features described above, which have been set forth merely by way of example, with the intent of most fully setting forth the teaching of the invention. Obviously, devices may be provided which change, eliminate, or add certain specific structural details without departing from the invention.