Pumps – Motor driven – Fluid motor
Patent
1994-01-24
1995-04-25
Gluck, Richard E.
Pumps
Motor driven
Fluid motor
F04B 4306, F04B 912, F01L 2102
Patent
active
054093554
DESCRIPTION:
BRIEF SUMMARY
This invention relates to diaphragm pumps operated by fluid pressure.
Examples of such diaphragm pumps are described in WO91/00417. For reasons of cost and facility of production, it is desirable to reduce the number of components required to assemble a pump. There may be particular advantages in this for pumps intended to be used in clean or sterile conditions, such as pumps used in medical and surgical procedures. In the said WO91/00147 one example of construction has an integrally formed diaphragm and gas outlet valve closure element interconnected by a collapsible stem, which can all be formed in a single moulding, but it is not simple to ensure that the resilient mounting that holds the closure element can close the valve reliably.
According to the present invention, there is provided a pressure-operated pump comprising a pumping chamber for the fluid to be pumped and a fluid pressure driving chamber having a valve-controlled outlet, a flexible diaphragm between said chambers and being displaceable by pressure in the driving chamber to expel fluid from the pumping chamber, said diaphragm being connected to a resiliently deformable member that includes a valve closure element for said driving chamber outlet and to an extensible tension element that urges the closure element to its operative closing position.
It is found that the provision of the tension element can give a more assured closure. In addition, it is possible to form the diaphragm, closure element and tension element as a single integral member. In contrast to the known pump described above, the connection between the diaphragm and the valve closure element need not apply a closing force to the valve closure element and it can be arranged to operate in a non-collapsible manner.
For efficiency of operation, it is desirable to arrange that the driving chamber outlet valve opens relatively quickly, preferably with a snap-action. For this purpose, the member is so formed that it is resiliently deformed during the pumping stroke, while the valve remains closed, the release of energy of deformation aiding the opening of the valve. For instance, a stem portion of the member connecting the diaphragm to the valve closure element can be arranged to be increasingly tensioned during the pumping stroke to urge the closure element away from the outlet while a pressure differential acts on the element restraining the opening of the valve. When said tension force is sufficient to displace the closure element and allow the countervailing pressure differential to drop, the stored tensile energy opens the valve the faster. Additionally or alternatively, resilient flexure of the valve closure itself can similarly store energy which is released to accelerate the opening movement of the valve.
It may be noted here that in the form of pump described above from WO91/00417, such snap-action does not occur because there is no release of stored energy at the instant of valve opening.
Preferably, the tension that holds the valve closed during a return stroke of the diaphragm is exerted by an element of said member acting as a weak spring having a relatively low rate as compared with the spring rate of the element or elements providing said stored energy. This is desirable in order to minimise the opposing force to said snap-action opening.
By way of example, the invention will be described in one particular form with reference to the accompanying diagrammatic drawings in which:
FIG. 1 is an axial section through a pump according to the invention, and
FIG. 2 is a plan view of the pump in FIG. 1.
The illustrated pump comprises a two-part casing 2 comprising upper and lower parts 2a,2b coaxially located by an integral circumferential rib and groove 6 and angularly located by integral spigot and bore connections 8. A diaphragm 10 is engaged sealingly between the two parts which are solvent-bonded together. The diaphragm divides the interior of the casing into a pumping chamber 12 and a driving chamber 14. Liquid to be pumped fills the pumping chamber 12 through an inlet 1
REFERENCES:
patent: 3429274 (1969-02-01), Nilsson
patent: 4662829 (1987-05-01), Nehring
patent: 4687423 (1987-08-01), Maget et al.
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