Patent Publication Number: US-7914263-B2

Title: Ejector-type rotary device

Description:
FIELD OF INVENTION 
     The present invention relates to a fluid-operated ejector type rotary machine, and more particularly, to a machine of the aforementioned type that consists of a compression section and a vacuum section. More specifically, the invention relates to a combined compressor/vacuum pump device that may operate either as a fluid compressor or as a fluid pump. In particular, although the invention is applicable to both liquids and gases, it is more advantageous to use the ejector-type rotary device as a gas compressor, or a gas pump. 
     BACKGROUND OF THE INVENTION 
     A jet ejector pump can be defined as a suction pump in which fluid under high pressure is forced through a nozzle into an abruptly larger tube where a high-velocity jet, at a low pressure in accordance with the Bernoulli law, entrains gas or liquid from a side tube opening just beyond the end of the nozzle to create suction. 
     Known in the art are ejector pumps of different types. 
     For example, U.S. Pat. No. 6,619,927 issued in 2003 to D. Becker, et al. describes an ejector pump provided in a fuel tank of a motor vehicle, which has a nozzle produced integrally with a mixing tube. The mixing tube is shaped in the form of a tubular cylinder, so that virtually the entire ejector pump may be produced from plastic in a mold allowing axial demolding. The nozzle is therefore aligned, exactly with respect to the mixing tube. The ejector pump consequently has a particularly high efficiency. 
     U.S. Pat. No. 6,394,760 issued in 2002 to P. Tell relates to a vacuum ejector pump. The ejector includes two or more nozzles arranged in series. A stream of air fed at high velocity through the nozzle is used to create a negative pressure in an outer, surrounding space. The surrounding space is in flow communication with at least one slot located between the nozzles. The nozzles are coupled together and assembled into an integrated nozzle body having at least one flexible valve member integrally arranged within the nozzle body to cover the flow communication with the surrounding space upon reaching a certain, desired pressure difference between the surrounding space and the atmosphere. 
     Russian Patent No. 2,247,873 issued in 2005 to A. Havkin, et al. relates to an ejector pump for delivery of various composite fluids to oil wells. The device comprises a housing, a union pipe connected to the housing which is used for the supply of the ejecting fluid, a union pipe for the fluid to be ejected, and a sleeve one part of the inner surface of which forms, in combination with the outer surface of the union pipe of the ejected fluid, an annular nozzle. This nozzle is connected to the pipe union of the ejecting fluid. The remaining part of the inner free annular space forms a mixing chamber, diffuser connected to the aforementioned chamber, and a pipe for discharge of the aforementioned mixture. 
     US Patent Application Publication No. 2005-2729 published in 2005 (inventor: S. Morishima) discloses an ejector pump which works to use dynamic energy of a jet of a main fluid emitted from a nozzle to suck a sub-fluid therein. When it is required to stop the ejector pump, the needle is moved to bring a sealing surface formed on a head thereof into abutment with a sealing surface formed around a main fluid flow path extending inside the ejector pump to close the main fluid flow path, thereby inhibiting the fluid pressure from acting on any downstream device. Upon the abutment, the needle is kept away from a nozzle, thereby avoiding undesirable wear or deformation of the needle and nozzle. 
     European Patent No. EP1378670 issued in 2004 to U. Engels describes a suction jet pump, which has an overflow beaker under its mixing tube. The mixing tube, complete with the diffuser on its outflow end, comes out into the beaker, which encloses it but is spaced out from it. It has an overflow aperture, which is fitted above the outflow end of the diffuser in the direction of flow. 
     Russian Patent No. RU2216651 issued in 2003 to S. Tsegel describes an installation for compression and delivery of different gaseous media to consumers. Proposed installation contains a pump, a separator and a liquid-gas jet apparatus. The pump is connected by its delivery side to an inlet of liquid into the liquid-gas jet apparatus, and by its suction side to the outlet of liquid medium from the separator. The liquid-gas jet apparatus is connected by gas inlet to a compressed gas source and by the gas-liquid mixture outlet to the separator. A branch pipe made on the housing of the separator in its upper part serves to let out compressed gas. Housing of the separator is partially filled with liquid medium. The separator is furnished with a drain chute, a set of phase separating nozzles and a louver pack. The drain chute is located along the separator housing. An inlet of the gas-liquid mixture in the separator from the liquid-gas jet apparatus is made over the inlet section of the drain chute. A set of phase separating nozzles is installed at the outlet of the drain chute, not higher that its outlet section. The louver pack is installed under the drain chute between the outlet of liquid medium from the separator and the set of phase-separating nozzles. 
     However, the ejector pumps described in the above references are designed for specific purposes, and none of them can be used as a universal pumping or suction machine for application in fields of industry for which it is not specifically designated. 
     It is known that existing centrifugal ejector pumps are characterized by simplicity of construction, high reliability of operation, (almost on the same level as that of a centrifugal pump that provides continuous supply of water to an ejector nozzle), and the highest volumetric/mass output capacity. However, the aforementioned existing centrifugal ejector pumps have low efficiency of energy use and are characterized by a limited field of applications (e.g., for evacuation and maintaining a reduced pressure in closed volumes). 
     A schematic view of a typical fluid-jet ejector nozzle is shown in  FIG. 1 . In fact, the pump shown in  FIG. 1  is a generalized version of the pumps described in the aforementioned patent publications of the prior art, except that in some of the previously described publications the fluid to be ejected is a liquid and in some is gas. 
     Such a fluid-jet pump, which as a whole is designated by reference numeral  20 , has a centrifugal pump unit  22 , which is driven into rotation by a motor  24  for sucking air from the surrounding atmosphere. The air is delivered along a pipeline  26  to a diffuser  28  that has a narrowed cross-section portion  30  as compared to the pipeline  26 . Existence of the narrowed cross-section portion  30  provides a reduced pressure in the area of the diffuser  28 . This effect is used for intake of a fluid from the space around the diffuser  28 . In the embodiment illustrated in  FIG. 1 , the aforementioned space is shown as a closed vacuum chamber  32 . The fluid that fills the vacuum chamber  32  is drawn into an outlet pipe  34 . For higher efficiency, the entrance into the outlet pipe  34  also may have a narrowed-section portion  36 . In fact, the space between the exit from the pipeline  26  and the entrance into the pipe  34  comprises the aforementioned diffuser  28 . In the above example, the air sucked by the pipeline  26  is an ejecting fluid and the fluid taken by the outlet pipe  34  is an ejected fluid. 
     In principle, and more often, the ejecting fluid used in the centrifugal pumps of the installations of the type described above, is a liquid, e.g., water, while the ejected fluid may comprise either a liquid or a gas. 
     An additional disadvantage of the pumps of the aforementioned type is inability of using thereof for compression of gases. 
     Furthermore, It should be noted that in a conventional ejector-type rotary machine the main source of all the losses is associated with movement of the working medium (which in most cases is liquid or gas) which is used as a carrier of energy for accomplishing the required work. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a highly universal ejector vacuum pump/compressor machine for application in various fields of industry. It is another object to provide the aforementioned ejector vacuum pump/compressor machine, which is characterized by high efficiency. It is still another object to provide the aforementioned ejector vacuum pump/compressor machine wherein the ejector effect is accomplished with a relative movement between a moving device and a “stationary” working medium. 
     A centrifugal-type ejector machine of the invention comprises a sealed hollow substantially cylindrical housing that contains a rotor rotatingly supported in bearings of the housing and driven into rotation by an externally located motor. The interior of the housing is filled with an ejecting fluid, e.g., liquid, such as water that surrounds the rotor. The rotor has a longitudinal channel for passage of the fluid to be extracted such as gas. The longitudinal channel of the rotor may be a central axial opening of the rotor. Furthermore, the rotor is provided with a plurality of radial channels, which are connected on their inner sides with the aforementioned axial opening of the rotor, while outer ends of the radial channels exit to the outer periphery of the rotor in a substantially tangential direction to the aforementioned outer periphery surface. The space between the inner surface of the housing and the outer surface of the rotor is filled with fluid-movement-retarding means, which is permeable to both extracting and extracted fluids. This may be, e.g., a mass of entangled wires that form fluid-passing cells. The mass of the wires can be packed into a net-like cylindrical cage. The outer surface of the cage can be fixed to the inner surface of the housing, while the inner surface of the cage may be in slight contact with the outer surface of the rotor. The housing has an outlet port to the atmosphere or to the device or appliance, which uses the machine as a compressor or a pump. On the side opposite to the motor, the rotor shaft has a longitudinal channel, or channels, or is made hollow, and the aforementioned channel, or channels, or the interior of the hollow shaft is/are connected to the aforementioned opening of the rotor. The inlet end of the hollow shaft can be used directly as an intake opening for the fluid which is to be extracted, e.g., as an air intake for sucking air from the atmosphere. Alternatively, the inlet opening of the hollow shaft can be connected to a vacuum chamber from which gas that fills the chamber will be evacuated to the rotor through the axial opening. By manipulating with the valves connected to the compression tank and to the vacuum chamber, the machine of the invention can be selectively used as a compressor, pump or as a source of vacuum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic longitudinal sectional view of the known centrifugal ejector pump. 
         FIG. 2  is a schematic longitudinal sectional view of the centrifugal-type ejector machine of the invention. 
         FIG. 3  is a cross-sectional view along line III-III of  FIG. 2 . 
         FIG. 4  is a partial cross-sectional view of the rotor. 
         FIG. 5  is a three-dimensional view of the cage that contains the flow-regularity destructing mass. 
         FIG. 6  is a cross-sectional view of the cage of  FIG. 5  without the flow-regularity destructing mass. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Analysis of existing patents and prior-art technique conducted by the applicants showed that all ejector pumps known to them are based on the use of a moving working medium as an energy-carrier that flows around or flows into a certain stationary device that provides interaction between the material to be pumped out and a flow of the working medium that entraps fragments of the pumped-out material and carries it away with the flow thus providing suction of a new portion of the aforementioned material. However, applicants found out that the ejector effect can also be realized in a device where a relative movement exists between a moving device and a “stationary” working medium. 
     A construction of the proposed centrifugal-type ejector pump/compressor [hereinafter referred to generally as a “centrifugal-type ejector machine”] of the present invention possesses all the advantages of the ejector pump and at the same time eliminates or significantly reduces a major part of the losses that lead to decrease in the pump/compressor efficiency. The proposed centrifugal-type ejector machine may operate in the following modes:
         evacuation of gas   compression of gas   evacuation and compression of gas;       

     pumping of liquid. 
     An example of a centrifugal-type ejector machine of the invention that may be used as a basis of a pump or a compressor operating on the principle of the combined centrifugal and ejector effects is described below with references to the attached drawings. Although the following examples describe the ejecting fluid as liquid and a fluid to be ejected as gas, it should be understand that such combination of fluids is given only as an example and that fluids of both types can be either liquids, or gases, or any combinations of liquid and gas. 
       FIG. 2  is a schematic longitudinal sectional view of the universal centrifugal-type ejector machine according to one example of the invention.  FIG. 3  is a cross-sectional view along line III-III of  FIG. 2 , and  FIG. 4  is a partial cross-sectional view of the rotor. 
     As can be seen from the drawings, the ejector pump, which in general is designated by reference numeral  100 , has a sealed hollow substantially cylindrical housing  102 , which can be made, e.g., from metal, ceramic, or plastic. The cylindrical housing contains a rotary shaft  104  arranged in the direction of an axial axis X-X of the cylindrical housing  102 . The rotary shaft is driven into rotation from a motor  106  located outside the housing  102  and is rotatingly supported in the housing  102  by bearings  108  and  110 , of which bearing  108  is installed in a side wall  102   a  of the housing  102 , and the bearing  110  is supported by a transverse partition  112  formed inside the housing  102  near the side wall  102   b  which is opposite to the side wall  102   a . A space between the partition  112  and the sidewall  102   b  defines an intermediate chamber  114 . 
     Connected to the sidewall  102   b  is a pump inlet pipe  116  that is used for the supply of a fluid medium to be ejected or pumped out, e.g., air, to the ejection pump  100 . It can be seen that the ejected fluid is supplied to the pump through the aforementioned intermediate chamber  114 . A space of the housing  102  between the sidewall  102   a , transverse partition  112 , and a cylindrical wall  102   c  of the pump housing  102  defines a working chamber  118  of the ejector pump  100 . 
     As shown in  FIGS. 2 ,  3 , and  4 , the rotary shaft  104  rigidly supports a rotor  120 , a cylindrical shape, and a round cross section. The working chamber  118  is filled with means  122  for retarding movements of the extracting fluid. For example, if the working chamber is filled with water, the purpose of the fluid movement retarding means  122  is to prevent water from rotation together with the rotor  120 . As can be seen from  FIGS. 2 and 3 , the rotor has a hollow interior  127  which is free of the fluid that fills the housing. 
     According to one example ( FIG. 3 ), the means  122  for retarding movements of the extracting fluid may comprise a cylindrical cage with fine irregular cells  123   a ,  123   b , . . .  123   n  for passing the flows of the fluid in an irregular mode from the interior of the working chamber to a pump outlet port  124 . The cells may be filled with a mass of chaotically arranged entangled wires  123 . 
     A more specific example of the fluid movement retarding means  122  is shown in  FIG. 5  which is a three-dimensional view of the means  122 . This unit comprises a cage  126  formed by two coaxial cylindrical grids, i.e., an outer cylindrical grid  126   a  and an inner cylindrical grid  126   b . The space between the outer cylindrical grid  126   a  and the inner cylindrical grid  126   b  is filled with the aforementioned mass formed by the entangled wires  123 . The wires having a diameter, e.g., in the range of 0.1 to 1 mm, and in order not to create a noticeable resistance to the flow of the pumped out gas, or liquid, an average size of the cells formed between the wires may range from about 1 mm to 5 mm or more. It is understood that the above numbers are given merely as examples. The purpose of the fluid movement retarding means  122  is to prevent entrapment of the liquid by rotation of the rotor because of the forces of viscous friction. 
     In order to prevent rotation of the cage  126  together with the rotor  120  because of the aforementioned forces of viscous friction, the cage  126  is fixed in the cylindrical housing  102 , e.g., by keys  130   a ,  130   b , . . .  130   n  ( FIG. 3 ). Appropriate key slots (not shown) for the keys  130   a ,  130   b , . . .  130   n  should be provided on the inner surface of the cylindrical housing  102 . The inner surface of the inner cylindrical grid  126   b  is maintained in a slight physical contact with the outer surface of the rotor  120 . In the context of the present invention, the term “slight physical contact” means friction contact between the outer surface of the rotor  120  and the inner surface of the inner cylindrical grid that allows the rotor to have a sliding contact with the inner cylindrical grid. 
       FIG. 6  is a cross-sectional view of the cage of  FIG. 5  made in accordance with an embodiment of the invention. The cage  128 ′ comprises an outer cylindrical grid  126   a ′, an inner cylindrical grid  126   b ′, and a plurality of intermediate cylindrical grids  127   a  between them. The inner cylindrical grid  126   b ′ is provided with radial longitudinal ribs  134   a ,  134   b , . . .  134   n . Other modifications are possible. 
     The rotor  120  is located on the shaft  104  in an intermediate position between the sidewall  102   a  and the transverse partition  112 . As shown in  FIG. 2 , the shaft  104  has a longitudinal channel  104   a , one end of which is open into the hollow interior  127  of the rotor  120  and the other end communicates with the intermediate chamber  114 . As can be seen from  FIG. 4 , the cylindrical wall of the rotor  120  has a plurality of circumferentially spaced radial channels  140   a ,  140   b ,  140   c , . . . . Near the outer surface or periphery  142  of the rotor  120 , portions  140   a   1 ,  140   b   1 ,  140   n   1 , . . . of the channels  140   a ,  140   b ,  140   c , . . . change their orientation to directions substantially tangential to the rotor periphery  142  ( FIG. 4 ) and terminate on the rotor periphery  142 . Reference numeral  124  ( FIGS. 2 and 3 ) designates an outlet port of the ejection pump  100 . 
     In order to make the centrifugal-type ejector machine of the invention more versatile with possibility of using this machine selectively in a compression or in a vacuum-pump mode of operation, the machine can be provided with a compression tank  111  ( FIG. 2 ). The compression tank  111  is connected with the pump outlet port  124  by a pipe  111   a  with a shut-off valve  111   b . The compression tank  111  has an outlet pipe union  111   c  with a shut valve  111   d  for connection to a device or an appliance working from compressed gas, e.g., a pneumatic power tool, or the like (not shown in the drawings). 
     If necessary, the centrifugal-type ejector machine of the invention may be further provided with a vacuum chamber  113  ( FIG. 2 ) that may be used as a source of vacuum or a reduced pressure, e.g., for removal of gases from a closed volume. The vacuum chamber is arranged on the gas-supply end of the machine and comprises a sealed container, which surrounds the pump inlet pipe  116 . The vacuum chamber may be provided with a shut off valve  113   a  that is located in the outlet pipe  117  and can be switched to the OFF position, e.g., for disconnecting the vacuum chamber, in which the vacuum has been developed to a predetermined level, from the pump section. The valve  113   b  is needed to prevent penetration of water from the pump into the vacuum chamber  113  when the motor  106  is deenergized. ( FIG. 2 ). 
     Operation 
     The centrifugal-type ejector machine  100  operates as follows. Let us first consider operation of the machine  100  in a compression mode. The motor  106  is activated and begins to rotate thus causing rotation of the rotor  120 . The outer surface  142  of the rotating rotor  120  interacts with the working liquid W that fills the interior of the working chamber  118  ( FIG. 2 ). The layer of the working liquid W that is in contact with this rotating outer surface  142  has a velocity much lower than the circumferential speed on the outer surface  142  of the rotor  120  (due to a dragging effect of the fluid movement retarding means  122  ( FIGS. 2 ,  3 ,  5 , and  6 )) and, hence, at the outlets of the channel portions  140   a   1 ,  140   b   1 ,  1240   c   1 , . . . formed in the rotor  120 . Since the aforementioned channel portions  140   a   1 ,  140   b   1 ,  1240   c   1 , . . . have directions which are close to the direction of tangents to the outer cylindrical surface  142  of the rotor  120  and since they are opposite to direction of rotation, it can be assumed that in the relative movement between the rotor  120  and the working medium W the latter flows around the profiles of the channel portions  140   a   1 ,  140   b   1 ,  1240   c   1 , . . . in the area of their exit from the rotor  120  in a substantially tangential directions. In this relative movement, the working medium W entraps fragments (portions) of the evacuated fluid, e.g., gas and separates them from the gas that remains in the channels  140   a ,  140   b ,  140   c , . . . . The layer of the working medium W with the entrapped gas is forced by centrifugal forces away from the rotating outer cylindrical surface  142  of the rotor  100  toward the inner walls of the device housing  102 . Fragments of the gas thrown to the inner walls of the device housing  102  are converted into gas bubbles B 1 , B 2 , B 3 , . . . ( FIG. 3 ). Since these gas bubbles have density, which is much lower than the density of the working medium W, the bubbles B 1 , B 2 , B 3 , . . . are quickly separated from the rotor outer surface  142 . The separated gas bubbles rise to the compression tank  111  ( FIG. 2 ), where the gas may be either compressed or released to the atmosphere. 
     If, in the embodiment of the machine  100  shown in  FIG. 2 , the valve  11   d  is closed and the valve  111   b  is opened, gas pressure in the compression tank  111  will grow to a predetermined value. For use as a gas compressor, the valve  111   b  is closed, and the valve  111   d  is opened for the supply of the compressed gas to the device or appliance (not shown) operating on compressed gas. Since the portions of the gas removed from the channels  140   a ,  140   b ,  140   c , . . . through the interaction of the rotor surface  142  with the surrounding working medium W are compensated by new portions of gas that is supplied through the hollow interior  127  of the rotor  120 , the gas evacuation process proceeds in a continuous manner (like in a conventional ejector pumps). 
     If necessary, the centrifugal-type ejector machine of the invention may be further provided with a vacuum chamber  113  ( FIG. 2 ) that may be used as a source of vacuum or a reduced pressure, e.g., for removal of gases from a closed volume. The vacuum chamber is arranged on the gas-supply end of the machine and comprises a sealed container, which surrounds the pump inlet pipe  116 . The vacuum chamber may be provided with a shut off valve  113   a  that is located in the outlet pipe  117  and can be switched to the OFF position, e.g., for disconnecting the vacuum chamber, in which the vacuum has been developed to a predetermined level, from the pump section. The valve  113   b  is needed to prevent penetration of water from the pump into the vacuum chamber  113  when the motor  106  is deenergized ( FIG. 2 ) [AMENDMENT C]. 
     Practical Example 
     Performance characteristics of the centrifugal-type ejector machine  100  of the invention were measured on a specific sample of the machine used by applicants as a test model. The test model had the following structural geometrical parameters:
         Inner diameter of the housing: 100 mm   Outer diameter of the rotor: 75 mm   Rotary speed of the rotor: 30; 40, and 50 revolutions per second;   Working medium: water   Flow-regularity destructing means: packing in the form of a large-cell Nylon grid       

     The following surplus pressures (relative to the surrounding atmospheric pressure) were obtained in the mode of compression of air taken from the atmosphere: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Rotary speed (rev/sec) 
                 Maximum pressure increase (mmHg) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 30 
                 60 
               
               
                   
                 40 
                 118 
               
               
                   
                 50 
                 210 
               
               
                   
                   
               
            
           
         
       
     
     The following reduced pressures were obtained in the mode of evacuation of gas with release to the atmosphere: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Rotary speed (rev/sec) 
                 Maximum pressure decrease (mmHg) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 30 
                 33 
               
               
                   
                 40 
                 77 
               
               
                   
                 50 
                 152 
               
               
                   
                   
               
            
           
         
       
     
     Scattering of measurement data (about 10%) that occurred in the test after each assembling/disassembling was caused by non-controllable position of the Nylon grid used for attenuation of the working-medium flow in the experimental device. However, performance parameters of the centrifugal-type ejector machine of the invention can be improved if the machine is manufactured with higher quality and accuracy that can be obtained in the commercial production. 
     Experiments were carried out for both horizontal and vertical orientation of the rotor and housing. In both cases the results were identical. 
     It can be assumed that the centrifugal-type ejector machine of the invention will have much higher efficiency than the conventional machine of this type since the device of the invention eliminates losses associated with high-speed movements of the liquid inside the centrifugal pump and in liquid-supply pipes and well as losses in connection with the release of the working liquid and energy stored therein. 
     Thus it has been shown that the present invention provides a highly universal ejector vacuum pump/compressor machine for application in various fields of industry, which is characterized by high efficiency and operates with a relative movement between a moving device and a “stationary” working medium. 
     Although the invention has been described with reference to specific examples and drawings, it is understood that these examples and drawings should not be construed as limiting the application of the invention and that any changes and modifications are possible without departure from the scope of the attached patent claims. As has been mentioned above, the extracted fluid is not necessarily gas, and the extracting fluid is not necessarily liquid, but both fluids may comprise any combination of gases and liquids. When both fluids are gases, the rotor should rotate with a very high speed. When the extracting fluid is liquid, it is not necessarily water and may comprise another liquid. The gas is not necessarily air and may comprise another gas. The cage with flow-regularity destructing means may be embodied in many other forms, e.g., may comprise a plurality of transversely arranged plates with a plurality of holes, etc. The rotor may have a cross-section not exactly cylindrical, e.g., it may have an elliptical or oval shape. The radial channels of the rotor may be used in different quantities with different arrangement patterns and with different cross-sections of the channels. The outlet ports of the aforementioned channels may have different profiles. The fluid movement retarding means may comprise a plurality of ribs attached to the inner walls of the housing and extending radially inward into the housing interior towards the rotor. The cage may be replaced just by the mass of entangled wires, and the longitudinal channel for the supply of the fluid to be extracted may be formed by a tube that concentrically embraces the shaft and forms an annular gap with the shaft for the supply of the fluid.