IL33790A - Pressure regulating structure for piston pump - Google Patents

Description

a regulating structure for piaton TEE AFA OF FLORIDA 32075 relates to liquid pressurising devices and in particular to a liquid pressurizing piston adapted to force a body of liquid under high pressure to a spray nozzle for developing a spray mis In many liquid dispensing devices in which a liquid is pressurized in a pump chamber of a cylinder type and particularly wherein the piston is actuated either manually or by resilient means such as a there is a noticeable and often rather longed pressure which takes place as the piston reaches the end of its liquid stroke in the This condition is particularly noticeable in liquid pumps wherein air is either intentionally or vertently mixed with a liquid in the or wherein a peculiar configuration of the parts of the dispensing it difficult if not impossible to eliininate all air pockets the passageways connecting the pump chamber with the liquid dispensing whenever due to air being a gas and thus readily compressible as to the liquid being as the piston approaches the end of its emptying stroke the hydraulic pressure drops off gradually due to the residual expansion action of the entrapped air creating this prolonged pressure condition is most noticeable when the discharge nozzle is controlled by a discharge valve which is held open as the piston is allowed to complete its pressurizing delivery aforementioned gradual pressure condition represents a serious problem In those liquid dispensing devices where constant high hydraulic pressure is as where the liquid pum is U3ed to urize liquid to be dispensed the form of a spray where the liquid is forced through a nozzle with a restricted orifice and the nozzle has some type of structure through hydraulic a fine mist or For one such liquid spraying device is that disclosed and claimed in Patent my application Serial filed entitled Spraying whioh is a con inua ion of my prior Should an air entrapment condition develop this a somewhat prolonged may occur at the end o the emptying stroke of the piston which in turn causes the liquid emerging from the nozzle to change from a high quality spray or mist into an annoying weak stream or object of the present invention is to vide a simple and Inexpensive pressure release mechanism for a liquid dispensing device which provides a instantaneous pressure cutoff whenever the liquid urizing piston reaches end of its delivery A more object is to provide an improved liquid spraying device of the type disclosed in my mentioned application incorporating a pressure cutoff release port which cooperates with a variable omatically maintain a pressure delivery rom pump chamber to the spray nozzle throughout substantially the entire working stroke of the Other objects as well as the features and dvantages of the present invention will become apparent from the following detailed description taken in tion with the accompanying drawing 1 a vertical center section illustrating hand pressurized liquid spraying device incorporating a pressure liquid pressurizing piston pump structure in accordance with the present the piston being shown at about its midst oke 2 is an enlarged fragmentary vertical tional view along the axis of device illustrating a portion of the structure shown 1 but with the piston shown at the end of its liquid pressurizing and delivery 3 a horizontal section take on the line of is a still further enlarged fragmentary elevatlonal looking outwardly from the center of the pump chamber the chamber port trating the piston from the in the same position in it illustrated Referring in more detail to the 1 illustrates a preferred example of a uniform pressure liquid delivery structure accordance my present invention applied to a liquid spraying device 10 such as Patent 065 that dicolosed and claimed my aforesaid application Serial fi to which reference be had for a more detailed disclosure of the and operation of liquid spraying device 10 comprises a manually liquid device which Includes a refillable container for holding a supply of the liquid to be the open upper end of which is closed by a cover structure Device 10 also includes a manually spring pressurized pump prising a piston l6 in a cylinder In the embodiment illustrated cylinde 18 is an integral part of cover whereas piston l6 l3 connected by rigid stem 20 to a spray head 22 which is siidable guided on the container by a dependent skirt 24 which also a hand hold for the Spray device 10 is cocked for spraying by pushing spray head 22 downwardly so that it telescopes onto container preferably while the container is supported as by resting it on a firm surface such as a table This movement drives piston 1β down on its suction stroke against the force of a yleldable coil spring causing liquid to be drawn from the body of liquid 28 in container up dip tube past inlet check valve 32 into the pump chamber 3 Chamber is defined between piston 16 and the fixed upper end wall 36 of chamber 34 which is formed by a piston retainer and plug insert 38 by rivets 40 to a screw top part 4 of closure This downward movement of piston 16 also simultaneously cocks spring 26 to its fully stressed The liquid under high pressure pump chamber 34 is operator depressing a spray button which opena a closed discharge valve 48 of the Valve 48 is ferably constructed in accordance with my United States Patent When it is desired to refill container 12 spray head 22 is rotated relative to container 12 to thereby unscrew olosure 14 from the closure 14 being keyed to head 22 by a key 50 which projects into a keyway 52 in skirt Referring in detail to 2 and it will seen that inlet check ball 32 seats in a valve body 4 and closes an inlet port which communicates with the upper end of dip tube Valve body 4 and dip tube 30 are both by press in a lateral protuberance Joined integrally to one side of cylinder l8 as best in 1 and The space above check ball 32 a valve 59 closed at its upper end by insert A flexible tube 60 extends in sealed relation through insert 38 to connect chamber 59 with valve A short passage 62 extends radiall of 18 between the upper end of pump chamber 34 and valve chamber 59 to form a combined for pump chamber In accordance with a principal feature of the present cylinder l8 provided with an escape port or lease passage adapted to connect pump chamber with a zone of pressure lower then that existent in the pump chamber when piston 16 almost at the end of its up which stitutes the fluid pressurizing or deliver stroke of the In the preferred embodiment disclosed this escape port constitutes a tapering groove 64 best seen in cylindrical interior wall 66 of cylinder 18 immediately below passage Groove 64 tapers to a point 68 at its lower end and the axis of the groove is inclined outwardly towards passage Preferably the upper end of groove 64 intersects with a radially extending groove 70 which passage 6 Groove 70 is out or molded into the flat bottom wall of a notch 72 in closure 42 which receives a keying looating projection 73 of insert Groove 70 has a cross seotional groove 70 being covered by projection The lower end 68 of groove 64 blends smoothly into the cylinder wall 66 at a point low rubber 74 when at its uppermost position as shown in and 74 serves as the liquid sealing element for bore and is carried between a flange 76 of piston 16 and a flange 78 of stem these parts together forming the The starting depth of the groove 64 at upper end will vary depending upon the relative size of the cylinder pump chamber piston stroke but the particular embodiment disclosed herein wherein the diameter of bore 66 approximately the length of the piston stroke is approximately inches and the parts are constructed by being scaled from the drawings herein utilizing these the depth of groove 64 at its upper end measured radially of cylinder 18 from the center of the groove to an imaginary extension of wall 66 is in the range of about to The inclination of groove 64 relative to the axis of cylinder 18 is approximately 15 The diametrical thickness of 74 should be about inches in its free state bled between flanges and axial compression with a slight squeeze so that it is distorted radially outwardly into liquid sealing engagement with wall and its piston groove are thus dimensioned relative to the diameter of bore 66 to produce a squeeze factor 3uch that the under compression radially by wall 66 out the working stroke of pisto It to be understood that the spring 79 formed within cylinder 18 the piston which spring 26 is housed is in with the interior of tainer 12 through an opening 80 in the bottom of cylinder fluid pressure in chamber 79 the as that of the head space 82 of container which in turn is tained substantially at atmospheric pressure through a Patent ing arrangement such those disclosed in my and application Serial or in ray application entitled Proof Container Serial In when piston l6 is travelling wardly from the lower limit of which to the of its liquid delivery or pressurizing stroke or the end of its intake stroke in broken lines until seal 7 starts to uncover lower end 68 of groove seal 7 maintains a liquid tight seal with wall 66 which prevents escape of the liquid pressure from pump chamber downwardly pact piston l6 to the zone of lower pressure comprising the chamber During this major portion of up stroke of the which is governed by release of the liquid trapped the nozzle in spray button 46 and hence a good quality spray 44 is produced by hydraulic in the Then just as piston l6 is almost at the top of cylinder 18 and thus is within say inches of the end of its travel on the up slides past the lower end 68 of groove thereby opening up a bypass passage to spray nozzle for the liquid under pressure to esoapa from chamber and from the ing passageways and downwardly between the ring and groove 64 to the radial olearance space normally vided between flange 76 and wall This olearance space in turn is in wide open communication via chamber 79 with head space assuming that the level of the liquid in the container below opening Even the liquid above this the pressure of the air trapped in chamber 79 is only very slightly above atmospherlo and hence much lower than the pressure seen by the liquid at the inlet to spray nozzle When the bypass port 64 is thus opened Just prior to piston 16 reaching the end of its up the liquid which amounts to only a drop or still remainin under pressure in pump chamber 34 squirts through the escape port thereby suddenly lieving pressure chamber 4 and allowing piston 16 to in the last of an inch of its up This completely empties ohamber 34 and oauees a very sudden and severe drop in the liquid pressure in passage 62 and valve cavity say from 100 to substantially atmospheric Hence the pressure exerted on the liquid at the inlet to nozzle which has been constant up to the aforementioned escape port opening is suddenly ended abruptly and a drarnatio instantaneous of the spray mist 44 This in turn has been found to successfully eliminate the annoying nozzle as th last of the liquid in chamber 34 is being dispensed and the contents of chamber are about to be and believed to be caused by an gradual pressure drop due to small bodies of air retained in the pockets of the structure forming the passageways 60 and valve As soon as the pump chamber pressure has been relieved by opening of escape port as described the escape port will automatically closed by expanding radially outwardly into groove 64 in response to the pressure Due to its resiliency 74 deforms and or protrudes into groove forming a protuberance 84 best seen in 3 which is effective to groove 64 unde these low pressure Thus when spray head 22 is pushed down to the spray device 10 and thereby draw liquid from container 12 up dip tube 30 into pump chamber 3 the suction created by the expanding volume of 3 cannot draw air from spring chamber 79 through passage 64 pump chamber 34 even during the time that 7 is travelling from its upper most position 2 and until it has passed wardly beyond the lower end 68 of groove Kence 74 acts as an automatic valve which insures that air does not become entrained in the liquid pressurizing conduits and chambers of the device as a result of the provision of the pressure relief of escape port In accordance with another feature of the present more uniform liquid delivery pressure is obtained throughout the working stroke of piston 16 by forming the bore 66 of cylinder 18 throughout the portion thereof engaged by and preferably the entire cylinder its extreme upper end dovm to opening with a configuration so that the wall of bore 66 converges downwardly and diverges upwardly with a slight Preferably this taper is approximately on the order of in a working bodiment of my invention constructed according to the mentioned dimensions when scaled from the drawing to these The tapered cylinder bore cooperates with the resilient 7 to help compensate for the variation in liquid pressurizing force developed by coil spring 26 for reasons of the same is a variable rate spring and hence exerts a higher force when fully stressed than when Due to the taper of bore 66 the greatest radial compression or is applied to seal when piston 16 is at the lower limit of its Therefore the f ictional dra of the seal 7 along wall 66 will be greatest during the first portion of the upward travel of piston 16 on its delivery As the piston moves the gradually increasing diameter of bore 66 causes a reduction in the unit pressure engagement force of 7 with bore thereby reducing the drag tance of the simultaneously with the in force exerted by spring 26 as it expands in driving piston 16 Thus the pressure developed in the liquid in pump chamber 3 is maintained more uniform throughout the working stroke of the with the pressure being sharply when the pressure relief bypass port 64 is opened as described The tapered cylinder bore is also advantageous in that it permits much easier and positive molding of cylinder 18 when the parts are Injection molded from plastic which i3 the preferred method of manufacture ployed in making my liquid spraying device From the foregoing description it will now be apparent that my invention provides a liquid pressurizing structure vrhich can be incorporated into liquid dispensing devices without the need for any added by very simple and low cost manufacturing operations and which will reliably function to automatically overcome the problems created by gradual pressure and will operate to maintain a more constant hydraulic pressure in such devices or 12 V insufficientOCRQuality

Claims (7)

1. A liquid pressurizing device comprising: a piston member having seal means slidably engaged in a cylinder member for defining a variable volume chamber, a spring between the members urging the piston member toward a terminal position in the cylinder member at which the volume of the chamber is a minimum, a manually operable discharge valve in a discharge conduit connected to the chamber through a discharge passageway that communicates with the chamber throughout the stroke of the piston in the cylinder, and a by-pass for venting the chamber when the piston reaches a pressure relief position adjacent to its terminal position, the by-pass including an inlet port opening into the discharge passageway and an outlet port opening into the cylinder at a point disposed on the side of the seal means on the piston remote from the pump chamber only when the piston is positioned between its pressure relief position and its terminal position.

2. A liquid pressurizing device according to Claim 1 wherein one of the members is on a container adapted to hold a quantity of liquid and to provide head space, and the other of the members is mounted in a head movably mounted on the container, movemen of the head in one direction serving to move the piston away from its terminal position to a position remote therefrom against the action of the spring and simultaneously draw liquid from the container into the chamber where it is pressurized by the spring acting on the piston, manual operation of the discharge valve permitting the spring to move the pisto toward its terminal position and force liquid in the chamber through the valve* p 33790/2 - 13 - •

3. A liquid pressurizing device according to Claim 2 wherein means are provided for maintaining the pressure in the head space at about ambient pressure, and wherein the cylinder on the side thereof remote from the chamber communicates with the container, the outlet port of the by-pass being located relative to the travel of the piston in the cylinder such that the eeal means moves past the outlet port when the piston reaches its pressure relief position.

4. A liquid pressurizing device according to any of the preceding claims wherein the spring comprises a variable rate compression coil spring,

5. · A liquid pressurizing device according to any of the preceding claims wherein at least a portion of the cylinder engaged by the piston seal means throughout the travel thereof has a gradually tapering diameter which increases in the direction of travel toward the terminal position of the piston and tends to decrease the chamber volume to thereby provide a gradual reduction in the frictional drag of the seal means along the cylinder as the spring moves the pisto toward its terminal position.

6. A liquid pressurizing device according to any of the preceding claims wherein the piston seal means comprises a resilient annular sealing member carried by the piston and radially compressed by the sliding engagement thereof with the cylinder walls, and wherein the by-pass comprises a shallow groove in the wall of the cylinder, the resilient seal extending into the shallow groove to reseal the same in response to release of liquid from the chamber* - 14 - -

7. A liquid pressurizing device substantially as described above by way of example and with reference to the accompanying drawings. For the Applicants TNERS DKSsCB