Fluid displacement pumps

Details Fluid displacement pumps Fluid displacement pumps

1999-05-26

2001-04-03

Dawson, Glenn K. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S074000, C604S315000, C604S320000

Reexamination Certificate

active

06210360

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to fluid displacement pumps, and more particularly to fluid displacement pumps which utilize a low-friction flexible partition within a rigid hollow body.
There are a great number and variety of pumps in the art. The typical purpose of a pump is to move air or liquid from one location or container to another. Generally, a piston is movable within the pump to create a negative pressure or vacuum which moves the fluid from one location to the other. Pumps can be manually actuated or connected to a mechanical device. One of the problems associated with prior art pumps is that they have typically produced a tremendous amount of friction between the piston and the cylinder in which the piston moves. This limits the efficiency of the pump and increases running costs.
Although the surfaces of the piston and cylinder can be lubricated, this is not acceptable in all applications. For example, in a nursing breast pump the extracted milk should be as pure as possible so as not to adversely affect the baby. Hand pumps which do not have lubricated pump surfaces exist, but they take longer to extract an adequate amount of milk due to the friction which must be overcome while pumping.
Therefore, what is needed is a pump which significantly reduces the friction between moving parts without the use of a lubricant. What is further needed is a pump which is capable of pumping greater volumes than existing pumps of comparable size. The present invention fulfills these needs and provides other related advantages.
SUMMARY OF THE INVENTION
The present invention resides in a fluid displacement pump comprising, generally, a rigid hollow body having first and second open ends, a flexible partition disposed within the hollow body adjacent to an open end, and an actuator acting upon the partition to define a variable volume chamber between the partition and the hollow body. The flexible partition is preferably comprised of a low-friction elastomeric material. In several embodiments, a piston having a shaft connected to the actuator and a head connected to the flexible partition is utilized. The rigid housing acts as a guide for the piston and a piston stop may be connected to the hollow body to limit the movement of the piston in these embodiments.
In a first illustrated embodiment of the invention, the fluid displacement pump forms a nursing pump having a breast engaging cup in fluid communication with the first open end of the hollow body. The breast engaging cup may comprise an inverted elastomeric bottle nipple having a one-way valve through which extracted milk enters the variable volume chamber. An elongated conduit may be used between the first open end of the hollow body and the breast engaging cup for convenience of the user. The actuator comprises a hand actuated pump handle which moves the piston and thus the partition. The nursing pump includes a pump handle guide member and stopper attached to the second open end of the rigid hollow body to limit the movement of the pump handle. The nursing pump may be configured such that a second hollow body also having first and second open ends and a flexible partition disposed within the second end of the second hollow body is inserted into the first open end of the first hollow body, and the breast engaging cup is attached to the first open end of the second hollow body such that actuation of the piston through the pump handle creates a negative pressure in both variable volume chambers for the extraction of milk into the variable chamber of the second hollow body.
In a second embodiment of the invention the actuator comprises a movable mass within the hollow body which movement is controlled by a linear motor associated with the hollow body. Fluid displacement bodies comprising a housing having first and second open ends and a flexible partition joined to the housing are disposed within the hollow body adjacent to an end thereof.
In a third embodiment a moveable mass is disposed within the hollow body and is cooperatively controlled by a pulley system connected to the hollow body and a pivot which supports the hollow body. At least one fluid displacement body comprising a housing having first and second open ends and a flexible partition disposed therein and joined to the housing near the first end of the housing, is disposed within the hollow body adjacent the respective first and second opposing open ends. A fluid transfer member in fluid communication with the second open end of the housing of the fluid displacement body has a flexible partition joined to a wall thereof to create a variable volume cavity.
In a fourth illustrated embodiment, the rigid hollow body includes closure members pivotally connected to each open end which are capable of closing and opening the respective open ends. When one open end is closed the contents of the fluid chamber move towards the opposing open end. This embodiment is intended to operate in a vacuum, such as outer space, which pressure differential would act as the actuator to move the variable volume fluid chamber.
In a fifth embodiment, the fluid displacement pump includes a second rigid hollow body connected to the first hollow body. A conduit fluidly interconnects the second end of the first hollow body and a second end of the second hollow body. The second hollow body has first and second open ends and a flexible partition disposed within the second hollow body connected adjacent to the first open end forming a variable volume fluid chamber within the second hollow body. The second hollow body also has a rigid head member attached to the flexible partition of the second hollow body and cutting elements pivotally connected to the second end of the second hollow body. The cutting elements are also connected to the rigid head member and close and open depending on the position of the rigid head member which is dictated by the movement of the flexible partition of the first hollow body.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.


REFERENCES:
patent: 4705504 (1987-11-01), Viers
patent: 4892517 (1990-01-01), Yuan et al.
patent: 4961726 (1990-10-01), Richter
patent: 5358476 (1994-10-01), Wilson
patent: 5749850 (1998-05-01), Williams et al.

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