Pump assembly with one piece piston

Details Pump assembly with one piece piston Pump assembly with one piece piston

2002-10-21

2004-08-10

Derakshani, Philippe (Department: 3754)

Dispensing

With resilient biasing means for outlet element

For elements reciprocable axially of discharge opening

C222S529000

Reexamination Certificate

active

06772920

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to pumps and, in particular, to nonaerosol pump sprayers.
BACKGROUND AND SUMMARY OF THE INVENTION
Noncontainer pressurizing pump sprayers commonly utilize an integral cylinder and plunger arrangement to generate pressure to expel liquid, such as insecticide and fertilizer from a container. Noncontainer pressurizing pump sprayers are desirable in that they do not utilize pressurized containers which must be handled carefully and at controlled temperatures to avoid the risk of explosion. Noncontainer pressurizing pump sprayers have a number of other advantages, including not using propellants which destroy the ozone and being relatively inexpensive.
There are two common varieties of noncontainer pressurizing pump sprayers: pump sprayers that are pressurized on the upstroke and pump sprayers that are pressurized on the downstroke. Pump sprayers that are pressurized on the downstroke typically utilize a return spring which biases the plunger upward after the pressurization stroke. These sprayers suffer from the drawback that it is often undesirable to store or ship the pump sprayer with the plunger in the up position. Accordingly, the pump sprayer is generally shipped and stored with the return spring in a compressed position, causing the spring to fatigue and begin to wear out prematurely. Likewise, in the event of the inadvertent release of the return spring, the plunger cannot be depressed without pressurizing the fluid in the container. In the case of insecticide or other toxic chemicals, this is often undesirable.
While pump sprayers that are pressurized by pulling the plunger upward have the advantage of not having the plunger being forced outward inadvertently, they too, suffer from a number of drawbacks. For example, once the plunger is drawn upward, it is generally not possible to lower the plunger without discharging fluid. As drawing the plunger upward creates a relatively large volume of pressurized liquid, this either requires that a relatively large amount of fluid be wasted or the device be stored with the plunger extending outward.
U.S. Pat. No. 4,174,055, to Capra, et al., discloses an alternative dispenser. The disclosed dispenser incorporates a plunger which pressurizes the fluid on the upstroke, but also is provided with a separate return spring and collar for purposes of lowering the plunger handle independently of the main plunger piston. While this arrangement has advantages, it is more complicated and expensive than other pump sprayer arrangements. Further, while the system provides for slow bleeding off of pressure, the sprayer remains in a pressurized state for some time. Significantly, this substantially increases the risk of inadvertent discharge of chemicals by adults or children who may come into contact with the device.
The present invention includes an apparatus and pump attachment particularly adapted to form a noncontainer pressurizing pump sprayer which overcomes the drawbacks of the prior art. The apparatus desirably includes an attachment having a pump sprayer which is pressurized on the upstroke, enabling the sprayer to be shipped and stored in a relaxed position. Importantly, however, the plunger is adapted to permit the plunger to be quickly and easily lowered and the apparatus depressurized without discharging fluid. Significantly, these advantages are provided in a apparatus which is particularly adapted to be inexpensively manufactured and includes few moving parts, to enhance reliability.
One aspect of the invention is a pump attachment for a container defining a neck including a body, a coupling, a shaft, a piston, an inlet valve and a biasing member. The body defines an elongate chamber having a first end, a second end, and an interior wall extending between the first end and the second end. The coupler is sized and shaped to secure the body to the neck of a container. The shaft extends through the opening in the first end of the chamber and defines an internal flow channel. The piston is reciprocally mounted within the chamber and defines an inner annular surface surrounding the shaft and an outer annular surface sized and shaped to form a sealing engagement with the interior wall of the body. The piston separates the chamber into an upper portion above the piston and lower portion below the piston. The inlet valve is at the second end of the body and is configured to permit the flow of fluid into the chamber and restrict the flow of fluid out of the chamber. The biasing member is positioned between the piston and the first end of the chamber.
The attachment defines a first sealing surface substantially fixed with respect to the piston and a second sealing surface substantially fixed with respect to the shaft. The first sealing surface and the second sealing surface have a first position wherein the first sealing surface and the second sealing surface cooperate to prevent the flow of liquid between the piston and the shaft. The first sealing surface and the second sealing surface have a second position wherein the first sealing surface and the second sealing surface permit the flow of liquid between the piston and the shaft.
Advantageously, the shaft includes an outwardly extending surface which prevents the piston from sliding beyond the one end of the shaft. Likewise, the attachment desirably includes a first O-ring mounted on the shaft which defines the second sealing surface and an inwardly tapered seat which defines the first sealing surface. Alternatively, the piston may comprise one piece and define an upper outer annular surface sized and shaped to form a sealing engagement with the interior wall of the body and a lower outer annular surface sized and shaped to form a sealing engagement with the interior wall of the body. Desirably, the upper outer annular surface is defined by an upper lip adapted to flex outward in response to downward pressure and the lower outer annular surface is defined by a lower lip adapted to flex outward in response to upward pressure.
The attachment may also include a spray nozzle communicating with the internal flow channel and an actuator for selectively preventing the flow of a fluid through the spray nozzle.
The attachment desirably includes a handle secured to the shaft and a latch movable between a first location wherein the latch generally prevents the shaft from being drawn through the first end of the body and the second location wherein the latch generally permits the shaft to be drawn through the first end of the body. Alternatively, the handle is integrally formed with the shaft so as to form a single piece plunger, thereby eliminating a potential leak point.
Another aspect of the invention is an apparatus including a container defining a neck and an attachment. The attachment includes a body, a coupler, a shaft, a piston, an inlet valve, and a biasing member. The body defines an elongate chamber having a first end, a second end and an interior wall extending between the first end and the second end. The coupler is sized and shaped to secure the body to the neck of the container. The shaft extends through an opening in the first end of the chamber and defines an internal flow channel. The piston is reciprocally mounted within the chamber and defines an inner annular surface surrounding the shaft and an outer annular surface sized and shaped to form a sealing engagement with the interior wall of the body. The piston separates the chamber into an upper portion above the piston and a lower portion below the piston. The inlet valve at the second end of the body is configured to permit the flow of fluid into the chamber and restrict the flow of fluid out of the chamber. The biasing member is positioned between the piston and the first end of the chamber.
The attachment includes a first sealing surface substantially fixed with respect to the piston and a second sealing surface substantially fixed with respect to the shaft. The first sealing surface and the second sealing surface have a first position wherein the first sealing surface and the secon

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