Fluid handling – Systems – With pump
Reexamination Certificate
1999-11-09
2001-07-17
Chambers, A. Michael (Department: 3753)
Fluid handling
Systems
With pump
C137S265000, C138S031000
Reexamination Certificate
active
06260577
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention refers to a method for transferring at least one liquid component from a remote source to a metering pump assembly and to a dispensing assembly for carrying out the method, comprising a metering device for at least one liquid component with a metering pump and a remote source for each component.
State of the art metering and mixing machines as commonly used for dispensing two component reactive resins systems such as epoxies, polyurethanes, silicones, acrylics and polysulphides, because of their size in having two chemical reservoirs and a metering system, usually have to be distanced well away from the point of resin mixing and use. It follows, therefore, that the individually metered resins have to be transferred through hoses to that point and because most resin systems are very resistant to flow, they require high pressure for that transfer. Also, because most resin systems are somewhat compressible, it is necessary to use small hose bores so as to minimise their individual content volume compression/decompression and smaller bores demand even higher pressures.
In addition, metering accuracy can be further affected by hose wall flexibility with expansion and contraction according to pressure changes, thus causing compression and decompression of their resin contents during the intermittent starting and stopping of flow. In order to counter all of these disruptive characteristics, sophisticated valves are usually fitted at the hose ends so as to maintain the high pressure within the hoses when metered flow has been stopped. However, this valving brings the additional disadvantages of restriction to the resin flow as well as additional complexity and cost.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to avoid the prior art compoundingly detrimental effects upon metering accuracy and the resulting complexity, as well as the required high pressure both for metering and transfer to the point of mixing and/or of application. This object is attained with a dispensing assembly wherein for each component the remote source is connected via a low pressure transfer pump and low pressure transfer hose to the inlet of the metering pump of the metering device as well as to the accumulator assembly situated immediately before the inlet of the metering pump.
With the aforementioned high pressure feeding systems it is necessary to shut off the flow of components after dispensing has taken place, thus involving complex valving devices. It is therefore a second object of the invention to avoid such complex valving devices and to ensure feeding of the dispensing device both while metering is taking place and also while metering has stopped. This object is attained with the method wherein the liquid components are low pressure transferred to the metering pump as well as to an accumulator assembly for each component and whereby the accumulator assembly is replenished independently of whether the metering pump is metering or not.
As described above, the dispensing device of the prior art is connected via a high pressure transfer hose to a remote high pressure metering pump. It is therefore a third object of the invention to provide for the feeding of a point of application metering and dispensing device without the need of high pressure feed. This object is attained with the method wherein the liquid components are transferred by low pressure from a remote source to accumulator storage containers located just prior to the metering pump inlets of the metering device.
Further embodiments and improvements are defined in the dependent claims.
REFERENCES:
patent: 3250218 (1966-05-01), Sinclair
patent: 4214681 (1980-07-01), Levine
patent: 4234007 (1980-11-01), Titone et al.
patent: 5020566 (1991-06-01), Shoop
patent: 5098666 (1992-03-01), Meinz
patent: 5477987 (1995-12-01), Keller
patent: 668 111 (1995-08-01), None
patent: 787 534 (1997-08-01), None
patent: 2 039 091 (1980-07-01), None
patent: 86/04047 (1986-07-01), None
patent: 96/27448 (1996-09-01), None
Chambers A. Michael
Foley & Lardner
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