US3912129A

US3912129A - Liquid dispenser

Info

Publication number: US3912129A
Application number: US510192A
Authority: US
Inventors: Jr Crawford R Meeks
Original assignee: Hughes Aircraft Co
Current assignee: Raytheon Co
Priority date: 1974-09-30
Filing date: 1974-09-30
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

An electro-mechanical device for intermittently dispensing a liquid. The liquid is dispensed by the combination of a vessel, a cylinder having its open end exposed to the interior of the vessel, a piston, and a solenoid coupled to the piston. The piston is normally biased in a position wherein it is completely disengaged from the cylinder. When the solenoid is energized, the piston is moved to a position wherein it is engaged with the cylinder thereby pumping the liquid out of the cylinder.

Description

' United States Patent [191 Meeks, Jr.

[451 Oct. 14, 1975 LIQUID DISPENSER [75] Inventor: Crawford R. Meeks, Jr., Culver City, Calif.

[73] Assignee: Hughes Aircraft Company, Culver City, Calif.

[22] Filed: Sept. 30, 1974 [21] Appl. No.: 510,192

[52] US. Cl. 222/189; 222/333; 222/385 [51] Int. Cl. B67D 5/58 [58] Field of Search 222/330, 189, 188, 333,

[56] References Cited UNITED STATES PATENTS 2/1936 Brady 222/333 X 7/1938 Lavine 222/385 X 2,423,173 7/l947 Brady et al. 222/189 3,333,741 8/1967 Radcliffe 222/189 3,521,789 7/1970 Kraft 222/334 X FOREIGN PATENTS OR APPLICATIONS 375,291 6/1932 United Kingdom 222/333 Primary Examiner-Robert B. Reeves Assistant Examiner-Hodd Lane Attorney, Agent, or Firm-W. I-l. MacAllister; William L. Androlia ABSTRACT An electro-mechanical device for intermittently dispensing a liquid. The liquid is dispensed by the combination of a vessel, a cylinder having its open end exposed to the interior of the vessel, a piston, and a solenoid coupled to the piston. The piston is normally biased in a position wherein it is completely disengaged from the cylinderQWhen the solenoid is energized, the piston is moved to a position wherein it is engaged with the cylinder thereby pumping the liquid out of the cylinder. f I

2 Claims, 3 Drawing Figures LIQUID DISPENSER FIELD OF THE INVENTION DESCRIPTION OF THE PRIOR ART It is frequently necessary, when the environment is a vacuum or near vacuum and gravitational forces are created by centrifugal force, to provide means for dispensing liquids which are unaffected by the environment. Since all liquids contain to various degrees dissolved gases, a special problem is created by the release of gas bubbles as the ambient pressure is lowered. The conventional piston and cylinder pumps which exist in the prior art will not operate in a vacuum because the inlet passages to the cylinder will not pass the bubbles of released gas thereby trapping the gases in the cylinder. Therefore, since the released gases cannot escape from the cylinder, the pump becomes vapor locked and ceases to operate.

Several means exist in the prior art for dispensing liquids in a vacuum which overcome the aforementioned problems. One of such means comprises a vessel of bellows type constuction, a check valve in the vessel, and an electro-mechanical solenoid which compresses the vessel when energized. When'the vessel is compressed, the check valve opens when its cracking pressure is exceeded thereby expelling deaerated liquid into a connection tube or passageway. One major problem with this type of dispenser is that over long periods of time repeated operations of the dispenser may cause fatigue of the bellows thereby resulting in leaks and eventual complete failure.

Another dispensing means which exists in the prior art is a pressurized vessel with an electro-mechanical valve. In such a dispenser, when the valve is energized, liquid is expelled from the vessel by the pressure in the vessel. A major problem with this type of dispenser is that since the valve is not perfect and is under continuous pressure, it may leak.

Accordingly, it is a general object of the present invention to provide a liquid dispenser whose operation is unaffected by a vacuum or near vacuum environment.

It is another object of the present invention to provide a liquid dispenser which operates in an environment where gravitational forces are created by centrifugal force.

It is yet another object of the present invention to provide a liquid dispenser which has a long operating lifetime.

SUMMARY OF THE INVENTION In keeping with the principles of the present invention, the objects are accomplished with the unique combination of a vessel, a cylinder having its open end exposed to the interior of the vessel, a piston having a first position wherein it is disengaged from the cylinder and a second position wherein it is engaged with the cylinder and a means for reciprocally moving the piston between the first and second position. When the piston moves from the first to the second position, it engages the cylinder and compresses the liquid contained therein thereby pumping the liquid out of the cylinder. Conversely, when the piston moves from the second to the first position, it withdraws completely from and disengages with the cylinder thereby allowing both liquid to flow from the vessel into the cylinder and released gases, which were formerly dissolved gases in the liquid, to drift out of the cylinderand into the vessel by buoyant forces. Therefore, since the released gases are allowed to drift out of the cylinder into the vessel, the pump does not vapor lock in a near vacuum or vacuum environment.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of the present invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, wherein like DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more specifically to the drawings, FIG. 1 and FIG. 2 are respectively a front elevation view and a plan view of a liquid dispenser in accordance with the teachings of the present invention. FIG. 1 and FIG. 2

are included to show the external appearance of the present invention thereby facilitating an understanding of its nature and operation. FIG. 3 is a sectional view of the present invention and contains sufficient detail to set forth the implementation of an embodiment of the present invention.

Referring to the dispenser shown in FIG. 3, the dispenser includes a central shell 2. Shell 2 is fastened to flanged base 4 by

screws

6, 8, 10 and 12 (shown in FIG. 2). Piston guide 14 and reservoir cover 16 containing cylinder 38 defined by the walls of a cylindrical bore in said cover 16 are fastened to shell 2 by

screws

18, 20, 22 and 24 (shown in FIG. 1). Discharge valve cap 26 is fastened to reservoir cover 16 by

screws

28, 30, 32 and 34 (shown in FIG. 1). Central shell 2, flanged base 4, piston guide 14., reservoir cover 16 and valve cap 26 constitute housing 36 (shown in FIG. 1).

Solenoid coil 40 is enclosed by housing 36 and surrounds axially movable magnetic core 42 which is pulled into coil 40 when the latter is energized. Hollow piston 44 is slidably mounted in piston guide 14 and in axial alignment with cylinder 38. Furthermore, the top portion of piston 44 slidably engages cylindrical bore 46 of core 42 and abuts interior shoulder 48 of cylindrical bore 46. Spring 50 is housed within cylindrical bore 46 of core 42 and surrounds piston 44. Furthermore, the two ends of spring 50 respectively abut exterior shoulder 52 of piston 44 and piston guide 14 thereby biasing piston 44 in a position wherein the latter is disengaged from cylinder 38.

Ball 54 is housed within discharge valve cap 26 and closes the end of cylinder 38. Furthermore, ball 54 is loaded by a compression spring 56. Discharge tube 58 is coupled to cylinder 38 via ball 54 and spring 56. The interior of housing 36 is exposed to the ambient atmospheric pressure via vent 60. Vent 60 is closed by screen 62 which is held in place by spacer 64 and plate 66. Plate 66 is fastened to housing 36 by screws 69 and 70 (shown in FIG. 1).

In practice, to insure that the buoyant forces are correct, housing 36 is aligned such that piston 44 is parallel to the direction of the gravitational forces.

In operation, piston 44 is normally biased by spring 50 in a position wherein piston 44 is disengaged from cylinder 38. When coil 40 is energized, magnetic core 42 is drawn into coil 40. Since piston 44 abuts interior shoulder 48 of core 42, piston 44 is driven forward toward cylinder 38 by magnetic core 42. As piston 44 moves forward toward cylinder 38, spring 50 is compressed. As piston 44 engages cylinder 38 and continues to move forward within cylinder 38, the liquid con tained in cylinder 38 is forced past ball 54 and in turn forces the liquid already in discharge tube 58 forward. Gas pressures are equalized by relief holes 47.

When coil 40 is de-energized, spring 50, which was compressed during the forward movement of piston 44, forces piston 44 and consequently core 42 back to their original positions wherein piston 44 is disengaged from cylinder 38. Since piston 44 is disengaged from cylinder 38, liquid 68 contained within housing 36 flows into cylinder 38. As liquid 68 flows into cylinder 38, any released gases contained within cylinder 38 drift out of cylinder 38 and into hollow piston 44 via holes 45 in said piston 44. The released gases drift through hollow piston 44 and eventually escape housing 36 via vent 60 and screen 62. Screen 62 is made of a mesh sufficiently fine such that it allows gases to pass through while impeding the flow of liquids.

ln all cases it is understood that the above-described embodiment is merely illustrative of but one of the many possible specific embodiments which can represent application of the principles of the present invention. Numerous and varied other arrangements can be readily devised in accordance with these principles by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

l. A liquid dispenser comprising:

a liquid-tight vessel having a vent to the exterior thereof;

a cylinder, said cylinder having its open end exposed to the interior of said vessel;

a check valve, said check valve closing the opposite end of said cylinder;

a piston, said piston having a first position wherein said piston is disengaged from said cylinder and having a second position wherein said piston is engaged with said cylinder, said piston being hollow, said piston further communicating at one end with said vent to the exterior and having at least one hole in the side of said piston adjacent to the other end of said piston which engages in said cylinder to vent gas from said cylinder to said exterior of said vessel;

a spring, said spring biasing said piston toward said first postion; and

a solenoid coupled to said piston, said solenoid being adapted to move said piston from said first position to said second position when said solenoid is energized.

2. A liquid dispenser according to claim 1 wherein said means for venting comprises:

a passageway between said interior and said exterior of said vessel; and

a screen, said screen closing the exterior end of said passageway.

Claims

1. A liquid dispenser comprising: a liquid-tight vessel having a vent to the exterior thereof; a cylinder, said cylinder having its open end exposed to the interior of said vessel; a check valve, said check valve closing the opposite end of said cylinder; a piston, said piston having a first position wherein said piston is disengaged from said cylinder and having a second position wherein said piston is engaged with said cylinder, said piston being hollow, said piston further communicating at one end with said vent to the exterior and having at least one hole in the side of said piston adjacent to the other end of said piston which engages in said cylinder to vent gas from said cylinder to said exterior of said vessel; a spring, said spring biasing said piston toward said first postion; and a solenoid coupled to said piston, said solenoid being adapted to move said piston from said first position to said second position when said solenoid is energized.

2. A liquid dispenser according to claim 1 wherein said means for venting comprises: a passageway between said interior and said exterior of said vessel; and a screen, said screen closing the exterior end of said passageway.