Pumps – One fluid pumped by contact or entrainment with another – Jet
Reexamination Certificate
2001-06-04
2003-06-24
Freay, Charles G. (Department: 3746)
Pumps
One fluid pumped by contact or entrainment with another
Jet
C417S179000, C417S198000, C417S182000
Reexamination Certificate
active
06582199
ABSTRACT:
The invention relates to a multi-stage ejector pump. More particularly, the invention relates to a multi-stage ejector pump having at least one housing element with at least one pressure gas intake opening, at least one suction gas intake opening, at least one exhaust gas opening, and at least one nozzle arrangement. The nozzle arrangement includes at least two nozzles (e.g., pressure gas nozzle, diffuser) positioned coaxially behind one another inside the housing element and axially spaced at distances from one another. The housing element includes a nozzle-receiving shaft having an essentially continuous shaft wall and at least one wall opening, an ejector step for the suction gas intake in the suction gas intake slit and the nozzles that equipped with at least one circumference sealing arrangement.
BACKGROUND OF THE INVENTION
For the simple manufacture of multi-stage ejector pumps, it is known in the art how to assemble the housing of the pump from individual parts, such as from a pump kit. Each part of the housing in the kit carries one of the nozzles in a transverse wall that intersects an interior space of the housing. If a multiple stage ejector pump is to be designed, this transverse wall of the housing may also carry several nozzles arranged side by side. Through the assembly of the parts of the housing, the pump is then ready for use. Here, installing the nozzles, e.g. by gluing them in or even by integrating the nozzle into the separating wall as a single part, is comparatively simple. However, many hermetic surfaces exist between the parts of the housing. The range of available designs for a compact pump arrangement are very limited. An ejector pump that is representative of the prior art for modular multi-stage pumps is disclosed in DE-C1-44 91 977, FIGS. 7 to 9.
There are also ejector pumps known, in which a continuous cast profile with inner separating walls is used, and the nozzles are installed in the individual separating walls angled to the axis of the profile through holes drilled in a terraced pattern. Most of the nozzles are located in the hollow spaces on both sides of the separating walls, which serve to distribute the gas. Although the above-mentioned hermetic surfaces are eliminated, adapting and tightening the nozzles is still difficult. Moreover, the compactness of such ejector pumps is not significantly better than the modular pumps mentioned above. For tight spaces, there are ejector pumps known with a compact design, in which the nozzles are pushed from different sides against a catch into a drilled hole in the housing to receive them. Due to such a design, ejector pumps of this kind can only be designed with one stage. It is not possible to interchange the nozzles.
Finally, there is a general multi-stage ejector that is known from DE 44 91 977, FIGS. 1 to 5, which is characterized in that a two-stage ejector nozzle system is designed as one piece and can be pushed into a nozzle-receiving shaft. In order to attain multi-stage properties, the one-piece axially designed nozzle body is connected with a suction opening by means of sections with a greater inside diameter. One of the limitations of using this type of pump design is that the manner of making the nozzles requires very costly shaping steps in the area of the undercut zones. Another limitation of this design is that only a cylindrical or conical course of the nozzle cross-sections located behind one another can be achieved. The supply of the pressure gas and the suction gas chamber are housed in flange-mounted components, which are connected with the housing body featuring the one-piece nozzle with screws, with the use of a large number of filigrane gaskets. The connection for the pressure gas and the connection for the suction gas are located in a lateral face arranged parallel to the nozzle channel inside the walls of the flange-mounted components of the housing. These gas connections face away from the nozzle axis at a right angle. The large number of additional sealing surfaces, in the area of the flange-mounted components of the housing makes this ejector pump prone to leaks. This risk is only slightly attenuated with the closed lateral walls of the housing base that run in a U shape along the nozzle configuration.
In view of the deficiencies of prior art ejector pumps, there is a need for a less costly ejector pump that has a compact design and is less prone to leakage during operation.
SUMMARY OF THE INVENTION
The principal problem to be solved by the present invention is to design a generic multi-stage ejector pump that is compactly constructed, includes interchangeable nozzles and has a high degree of effectiveness. To resolve the problems of prior art multi-stage pumps, there is provided a multi-stage ejector pump which includes at least one housing element. The housing element includes at least one pressure gas intake opening, at least one suction gas intake opening, at least one exhaust gas opening, and at least one nozzle arrangement. The nozzle arrangement, such as an ejector nozzle system, includes at least two nozzles (e.g., pressure gas nozzle and/or one or more diffusers) that are positioned coaxially behind one another inside the housing element and axially spaced at distances from one another. The ejector nozzles also includes an exhaust gas outlet opening, at least one pressure gas intake opening, and at least one suction gas intake slit between adjacent nozzles and an exhaust gas outlet opening. The housing element also includes a nozzle-receiving shaft (e.g., a drilled hole) having an essentially continuous shaft wall and at least one wall opening (e.g., connection opening). The housing element also includes a step for the suction gas intake in the suction gas intake slit. The nozzles on their outer circumference are equipped with at least one circumference sealing means. The ejector nozzle system is designed to be axially inserted into the nozzle-receiving shaft. The ejector nozzle system also includes a set of individual nozzle spacers. The nozzles are also equipped with support elements that are axially spaced for its tilt-free or low-tilt support in relation to the shaft wall when the nozzles are inserted into the nozzle-receiving shaft. At least one clamping means, such as a connection plate, is provided to axially clamp or hold in position the individual nozzles and the nozzle spacers in the nozzle-receiving shaft.
In one embodiment of the invention, the ejector nozzle system should consist of a set of individual nozzles (e.g., pressure gas nozzle, diffuser) and nozzle spacers, whereby the spacers leave open a space for the entry of gas between the adjacently spaced nozzles. As periodically referred to in this specification, the pressure gas nozzle and/or one or more diffusers of the ejector nozzle system are referred to as nozzles. The nozzles can be inserted into the nozzle-receiving shaft one after the another. By using this arrangement of nozzles, each of the nozzles can be shaped at both ends in a manner that will increase their performance. In addition, each individual nozzle has at least two support elements that are axially spaced to provide for a tilt-free or low-tilt support in relationship to the shaft wall. Only in this way is the design of individual nozzles with optimized performance possible, and which provides for the simple orienting of the nozzles to a common nozzle axis, without the need to glue the nozzles on to the nozzle-receiving shaft. While a press fit of the nozzle is conceivable, preferably O-rings are used as a means of sealing the outer circumference of each individual nozzle. The support elements can be cams that are distributed around the circumference of the nozzles, or something similar, but they can also be O-rings or similar means of sealing. The use of cams have the advantage of fulfilling a twofold function, since the cams serve as means of sealing at the same time as providing a tilt-free or low-tilt support. In order to position the nozzles and the nozzle spacers with precision, at least one means of clamping is provided.
Fay Sharpe Fagan Minnich & McKee
Freay Charles G.
Solak Timothy P.
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