Pumps – One fluid pumped by contact or entrainment with another – Jet
Patent
1995-02-01
1996-12-17
Thorpe, Timothy S.
Pumps
One fluid pumped by contact or entrainment with another
Jet
417161, 417182, 417151, F04F 500
Patent
active
055846688
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP93/02085 filed Aug. 5, 1993.
BACKGROUND AND SUMMARY OF THE INVENTION
Ejector pumps of this kind have been known for some time (FR-A1-25 77 284) and are being used for both, to generate vacuum and to move materials, capable of flowing. With a known sequential multistage design, a high degree of efficiency can be obtained, especially with high vacuum. This one has the advantage, that the flow energy of the working fluid, which can either be in gaseous or liquid form, is being used until the flow velocity has dropped below a level, which no longer can be used with any constructive effort.
Multi stage ejector pumps basically have the problem, in that the package size increases super-proportionally with the number of stages. This fact among others is due to the fact, that the cross sectional area of the flow channel has to increase from one stage to the next, and this will tend to expand the height of such an ejector assembly with several stages, without actually being able to use all of the entire volume. One example of this is an ejector pump having a square shaped housing.
The goal of this invention is, to improve ejector pumps of the type previously mentioned, so that in spite of the necessary enlargements of the flow channel, package size and especially package height can be kept small.
This task will be solved with an ejector pump having multiple pump stages for suction or for moving materials or material mixtures which are capable of flowing with the help of a working fluid within one housing. This is further accomplished with the ejector pump having a flow channel being circular in shape and constructed for a radially outward directed flow.
The ejector pump, according to this invention, in spite of extreme compactness and efficiency, can be easily manufactured, especially from (mass) turned or assembled parts. It can be manufactured from almost any material, as for example from metal, plastic, glass, ceramic, etc.
The principle of using a circular shaped flow channel for an ejector pump is basically already know from DE-A1-34 20 652--but solely for single stage ejector pumps. With this single stage ejector pump, it was basically a matter of high precision in order to realize very specific angular relationships and lengths in the area of the nozzle, the mixing zone and the diffuser. This could be accomplished by fashioning all essential parts such as the nozzle, mixing zone and diffuser on one or both faces as solid blocks, which could be accomplished in single phase, using a CNC controlled lathe. It resulted in high precision and good repeatability in the manufacturing of a large number of pumps. One significant disadvantage of this well known ejector pump is the fact that it consist of only a single stage. Another significant disadvantage is the fact, that the suction chamber, through which the flow medium or flow medium mixture is advanced towards the circular shaped, radially outward directed flow channel, is fashioned as a groove increasing its cross-section towards the flow channel, whereby the charging of this circular shaped groove with the flow medium or flow medium mixture take place through several, connecting openings spread out over the circumference, all of which end in a common antechamber. This type of construction, and the corresponding manufacturing process of these well known ejector pumps, results in undesirable flow relationships, for the flow medium or flow medium mixture as it is entering the circular shaped flow channel. An additional disadvantage of this well known ejector pump relates to the fixation on the very specific surface contour to be used for the flow channel. This allows an optimal pump efficiency only when the viscosity of the working fluid and/or of the flow medium or flow medium mixture lies within narrowly defined parameters. Different pumps each time are required to solve differing flow requirements, especially when moving a flow medium or flow medium mixture. Further problems are encountered if the viscosity of the same devia
REFERENCES:
patent: 3352348 (1967-11-01), Daviau
patent: 4048798 (1977-09-01), Larkins, Jr.
patent: 4938665 (1990-07-01), Volkmann
International Search Report, dated Nov. 16, 1993
Kim Ted
Thorpe Timothy S.
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