Abstract:
The present invention relates to a turbocharged internal combustion engine (ICE) system having fast response to increased power demand and reduced response time lag. The system includes a vortex tube for delivering cold air into the turbocharger compressor where it may be used to cool the impeller, and/or accelerate the impeller rotational speed, and/or favorably shift the compressor surge line at low speeds and high loads. Cold air from the vortex tube may be also used to operate an ejector pump in the intake duct which further compresses intake air and increases engine charge weight during periods of high power demand. In addition to increasing engine output power, delivery of cold air into engine intake also reduces engine pre-ignition (knocking) thereby reducing emissions. The invention also relates to a method for operating a turbocharged internal combustion engine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS: 
       [0001]    This patent application is a continuation-in-part patent application of: U.S. Ser. No. 11/655,441 filed on Jan. 19, 2007 and entitled SUPERCHARGED INTERNAL COMBUSTION ENGINE SYSTEM; U.S. Ser. No. 11/443,424 filed on May 29, 2006 and entitled SUPERCHARGED INTERNAL COMBUSTION ENGINE; and U.S. Ser. No. 11/389,795 filed on Mar. 27, 2006 and entitled SUPERCHARGED INTERNAL COMBUSTION ENGINE, the entire contents of all of which are hereby expressly incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to supercharged internal combustion engines and, more particularly, to compressors for superchargers capable of fast response to engine demand and delivering high boost during low engine speed. 
       BACKGROUND OF THE INVENTION 
       [0003]    Turbocharging of Internal Combustion Engines: One of the long-term goals of the automotive manufacturers is to reduce fuel consumption and emissions of modem automotive vehicles powered by internal combustion engines (ICE) while increasing engine efficiency. One approach to reaching this goal is reducing the ICE displacement. However, smaller engines having reduced swept volume typically exhibit insufficient power and torque when operating with normal aspiration. This problem can be remedied by supercharging. It is well known in the art that ICE power output increases with increased weight of air ingested into engine cylinders and available for combustion. Weight of intake air ingested into engine cylinders can be increased by either (1) increasing the pressure of intake air beyond what can be accomplished by natural aspiration or by (2) reducing the temperature of intake air or by (3) a combination of (1) and (2). A supercharged ICE, therefore, receives combustion air with higher density than a normally aspirated ICE. As a result, supercharging allows generating increased power from an engine of a given displacement or, generating a given power output from an engine of smaller size, weight, cost, and emissions. In addition, reduced charge temperature is known to reduce ICE emissions by decreasing charge pre-ignition also known as knocking. 
         [0004]    One commonly used type of a supercharger is the exhaust-gas turbocharger which typically includes a turbine and a centrifugal compressor on a common shaft. The turbine is rotated by exhaust gases from the engine and spins the compressor. The compressor receives intake air, compresses it, and supplies it to ICE combustion chamber(s). Turbochargers provide the advantages of relatively smooth transition from natural aspiration to supercharged operation while utilizing some of the residual energy of hot exhaust gas, which would otherwise be largely wasted. The challenges of constructing a turbocharged ICE include: 1) reducing as much as possible the response time lag, 2) broadening of the compressor working regime, and 3) reducing the exposure of compressor impeller to high temperatures and stresses. Information relevant to attempts to overcome these challenges and the disadvantages of such attempts are described below. 
         [0005]    A turbocharged ICE is susceptible to a slow response time known as the “turbo lag” which is caused by the low pressure and low quantity of exhaust gases that are available to operate the turbine at low engine speeds. This translates to insufficient quantity of intake air delivered to the engine and results in insufficient torque at low engine speeds. The turbo-lag problem may be corrected in-part by the use of a variable nozzle turbine, which alters the cross-sectional area through which the exhaust gas flows in accordance with engine speed. However, this approach adds complexity and cost while reducing reliability. Another approach to reducing the turbo lag may use one or more jets of air injected onto the compressor wheel of a turbocharger as disclosed, for example, by Williams et al. in U.S. Pat. No. 3,190,068. Such air jets may be directed generally onto the vanes of the compressor wheel so as to transfer a part of their momentum to the wheel and thus accelerate the rotational speed of the compressor. Air injected in this manner becomes a part of the intake air ingested by the engine. Yet another approach may use air jets injected into the diffuser part of the compressor as disclosed by Schegk in U.S. Pat. No. 5,461,860, the entire contents of which is hereby expressly incorporated by reference. Neither said Williams nor said Schegk disclose injection of cold air into compressor housing or compressor components. 
         [0006]    Performance of a turbocharger compressor is often described in terms of a characteristic diagram which defines the working range of the compressor by plotting the ratio of compressor output pressure to its input pressure as a function of the air mass throughput through the compressor. The compressor working range in the characteristic diagram is limited by a so-called “surge limit.” The surge limit represents a characteristic curve which curbs the output of the compressor in the regime of combined low mass throughputs and a high output pressure. This regime corresponds to an ICE operating at high load and a low rotational speed. With the compressor operating close to the surge limit, local zones of detached flow may be formed, which may result in periodic pulsation of the flow, change in the flow direction and acoustic noise. To increase the operating range of the compressor in the regime of high-loads and low-speeds it is desirable to shift the surge limit towards lower mass throughputs. The surge limit may be favorably shifted by means of characteristic-diagram stabilization measures such as a bypass which bridges compressor outflow port and inflow port. In particular, the bypass returns part of the compressor output flow into the compressor the inflow port and directs it on the compressor-impeller inlet edge as disclosed, for example, by Sumser et al. in U.S. Pat. No. 6,813,887 the entire contents of which is hereby expressly incorporated by reference. If the compressor operates close to the surge limit, the bypass allows recirculation of a predetermined portion of the compressor output stream back to the compressor inflow port. Sumser also discloses an ICE having an auxiliary air feed which supplies auxiliary air at ambient temperature through an injection opening in a wall of the compressor inlet and directs it into the flow-facing region of the compressor wheel. Auxiliary air injected in this manner influences the surge limit in favor of a regime with lower mass throughputs and high compressor pressure ratio. As a result, compressor working range is broadened. Furthermore, injected auxiliary air beneficially drives the compressor impeller, thereby helping the turbocharger to accelerate to its normal operating speed range. As a result, high charging pressures may be attained more rapidly, the undesirable turbo lag is reduced, and the turbocharged ICE may accelerate from low speed in a rapid, smooth manner. However, said Sumser does not disclose injection of cold air into compressor housing or compressor components. 
         [0007]    Experience shows that when turbocharger delivers high supercharging pressures, the compressor components experience high thermal loading. This may necessitate that such components are either fabricated from high-temperature materials, which are costly and difficult to machine or that such components are actively cooled, which has limited effect and adds complexity. This problem may be alleviated by cooling the air recirculated via a bypass from the compressor outflow port back to the compressor inflow port as disclosed by Scheinert in U.S. Pat. No. 7,021,058 the entire contents of which is hereby expressly incorporated by reference. In particular, Scheinert discloses a temperature reducing unit comprising a diffuser in a form of an expansion duct employed to cool the recirculated air before it is directed onto compressor wheel. However, temperature reduction achievable by Scheinert&#39;s temperature reducing unit is very limited. 
         [0008]    Vortex Tube for Cooling of ICE Intake Flow: Vortex tube is a well known cooling device in the art of refrigeration. Traditional vortex tube comprises a slender tube having one end closed except for a small a central opening and the other end plugged except for an annular opening which may be adjusted in size for flow control, see  FIG. 1 . A stream of high-pressure air (or other suitable gas) is injected through an inlet port tangentially into the tube in the proximity of the central opening. Resulting vortex flow pattern inside the tube separates the input air stream into a relatively hot air stream which exits through the annular opening and a relatively cold air stream which exits through the central opening and the cold outlet port. Relative flow rates and temperatures of these two streams are typically adjustable by controlling the flow of the hot exhaust stream. See, for example, article entitled “The Vortex Tube as a Classic Thermodynamic Refrigeration Cycle,” by B. K. Ahlbom et al., published in Journal of Applied Physics, Volume 88, Number 6, pp. 3645-3653, Sep. 15, 2000. A variant of the traditional vortex tube suitable for generating only a cold output stream can be produced by entirely closing one of the tube ends combined with active cooling of the tube exterior surface such as shown in  FIGS. 2A and 2B  and disclosed, for example, by Zerr in U.S. Pat. No. 4,612,646. Suitable cooling may be provided by a cooling jacket which may envelop the exterior surface of the tube. Suitable coolants may be provided in liquid or gaseous form. The exterior surface of the tube can be further provided with surface extensions to facilitate improved heat transfer as disclosed, for example, by Tunkel et al. in U.S. Pat. No. 5,911,740. 
         [0009]    Lindberg et al. in U.S. Pat. No. 6,247,460 discloses an ICE having a vortex tube for cooling intake air. Lindbergh&#39;s vortex tube generates both cold and hot outputs with only the cold output supplied to ICE intake. All of the intake air flows through the vortex tube at all times. When used on a supercharged ICE, the pressure drop of intake air inside the vortex tube robs the ICE of the pressure boost provided by the supercharger and wastes much of the supercharger output into vortex tube hot flow. Similarly, when used on a naturally aspirated ICE, the vortex tube impedes intake air flow thereby significantly reducing the intake air pressure. In each case the benefit of providing cooler air to the ICE is accomplished at the expense of reducing the intake air pressure. In particular, data of some vortex tube manufacturers suggests that the pressure ratio between vortex tube inlet port and its cold outlet port should be at least 2.4. See, for example, Catalog No. 21, page 102, published by Exair Corporation, Cincinnati, Ohio. Since cooling of the intake air and reducing its pressure have opposite effects on air density, the net benefit of Lindberg&#39;s apparatus, if any, is rather limited. Holman et al. in the U.S. Pat. No. 6,895, 752 discloses a turbocharged ICE with an exhaust gas recirculation (EGR) system wherein ICE exhaust is directed to a vortex tube to generate a cooler flow and a hoter flow. The cooler flow is directed to ICE intake to recirculate part of the exhaust gas while the hot flow may be exhausted from the ICE in a conventional manner. 
         [0010]    In summary, prior art does not teach a turbocharged ICE system that is effective during the conditions of high torque and low engine speed, has a fast response to power demand, is simple, economical, avoids exposing compressor components to excessive temperatures, and reduces susceptibility to charge pre-ignition. Furthermore, the prior art does not teach a turbocharged ICE system where turbocharger operation is augmented by injection of cold air from a vortex tube. Moreover, the prior art does not teach a turbocharged ICE system where turbocharger compressor is cooled by cold air from a vortex tube. It is against this background that the significant improvements and advancements of the present invention have taken place. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a turbocharged ICE system wherein the turbocharger assembly comprises a vortex tube that supplies cold, dense air to the ICE intake. When such cold air is supplied to a turbocharger compressor in the ICE intake, it may beneficially increase the compressor surge limit, cool the compressor blades, and accelerate the compressor speed. Faster compressor speed is conducive to generating higher charge pressure. In addition to increasing the charge pressure, injection of cold dense air may cool the engine intake air, which may further increase the weight of ICE charge and thus enable the ICE to produce more output power. Injection of cold air in the form of high-velocity jet onto compressor impeller may also enhance transfer of kinetic energy from the jet to the impeller and promote further increase in impeller speed. Cold air from the vortex tube may be also injected into the flow of intake air downstream of the compressor impeller either into the compressor diffuser or into the engine intake duct. In particular, cold air may be injected into the intake duct as one or more high velocity jets arranged to entrain and pump engine intake air, thereby increasing charge air density both by compression and by cooling. Suitable cold air injector may be a nozzle adapted for subsonic, sonic, or supersonic flow regime. Furthermore, the injector in the intake duct may be a driving nozzle which may also include lobes to enhance mixing. The compressed air for operation of the vortex tube may be obtained from the turbocharger compressor output flow or it may it may be supplied from an auxiliary air source. Suitable auxiliary air source may include an auxiliary compressor and/or an air tank. 
         [0012]    The vortex tube for use with the subject invention is preferably adapted for generation of cold output stream only. Such a vortex tube may include a cooling jacket or a heat exchanger which transfers heat from the vortex tube to either liquid coolant, gas coolant, air, ballast structure, or a phase change material (PCM). The turbocharged ICE system of the subject invention may further include means for regulating the flow and/or pressure of high-pressure air fed to the vortex tube and thereby regulating the air cooling action. In addition, the turbocharged ICE system may include means for sensing ICE power demand and appropriately controlling the operation of the vortex tube and the turbocharger to supercharge the ICE in response to demand. 
         [0013]    In one preferred embodiment of the present invention particularly useful for transient operation during times of increasing ICE power output, compressed air from an auxiliary compressed air source is cooled in a vortex tube and injected into the housing of a turbocharger compressor. In particular, cold air may be injected into the flow facing region of the compressor impeller, and/or onto the edge of impelled blade, and/or into the compressor diffuser. This embodiment is particularly useful for improving the performance of a compressor during periods of increasing ICE power demand. In another preferred embodiment of the present invention, a portion of the supercharging compressor output compressed air stream is cooled in a vortex tube and injected back into the housing of a turbocharger compressor. This embodiment is particularly suitable for turbochargers having high compression ratio (including multiple stage turbochargers) where it is useful for substantially continuous improvement of compressor performance such as may be desired during generally continuous operation. In yet another embodiment, compressed air from an auxiliary compressed air source is cooled in a vortex tube and injected into the engine intake duct downstream of the compressor. Cold air injected into the intake duct may be mixed with intake air from the exhaust-gas turbocharger. The resulting intake air mixture is colder and denser, which results in increased weight of ICE charge. Furthermore, the injector may be a driving nozzle arranged to pump intake air into the engine combustion chamber. In a still another embodiment, compressed air from an auxiliary compressed air source is cooled in a vortex tube and it is used to operate an ejector arranged to pump intake air at times of increasing ICE load. When the ejector is not needed, intake air may bypass the ejector through a bypass duct. The auxiliary compressed air source may also include an auxiliary compressor and/or an air tank for providing compressed air to the vortex tube. The auxiliary compressor may be driven by the ICE output shaft, vehicle drive train, an electric motor, or by other suitable means. The auxiliary compressor may be adapted to be preferentially engaged during periods of low ICE load and/or to recover kinetic energy during vehicle deceleration. A variant of the invention includes a vortex tube having a cooling jacket filled with PCM. During vortex tube operation, high-temperature air generated inside the vortex tube is cooled by transferring its heat into the PCM. Between supercharging events, heat is removed from the PCM and transferred to liquid coolant, gas coolant, or air. Another variant of the vortex tube may include a provision for storing heat as a sensible heat in vortex tube ballast structure. 
         [0014]    Accordingly, it is an object of the present invention to provide a turbocharged ICE system which may generate a high volume of intake air flow at high pressure during the conditions of high load demand and relatively low engine speeds. The turbocharged ICE system of the present invention is simple, lightweight, and inexpensive to manufacture which makes it suitable for large volume production of automotive vehicles. 
         [0015]    It is another object of the invention to provide a turbocharger assembly that has a fast response to output demand conditions. 
         [0016]    It is still another object of the invention to reduce the temperature of ICE intake air delivered by a turbocharger. 
         [0017]    It is yet another object of the invention to cool a supercharger compressor especially during conditions of high loading. 
         [0018]    It is yet further object of the invention to pump intake air into an internal combustion engine. 
         [0019]    It is a further object of the invention to beneficially broaden the operating range of a turbocharger compressor. 
         [0020]    It is still further object of the invention to beneficially shift the surge limit in a turbocharger compressor at times of high load and low speed of associated engine. 
         [0021]    These and other objects of the present invention will become apparent upon a reading of the following specification and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0022]      FIG. 1  is a cross-sectional view of a vortex tube of prior art suitable for concurrent generation of hot and cold output streams. 
           [0023]      FIG. 2A  is a cross-sectional view of a vortex tube of prior art suitable for generation of cold output stream only. 
           [0024]      FIG. 2B  is a cross-sectional view of an alternative vortex tube of prior art suitabled for generation of cold output stream only. 
           [0025]      FIG. 3  is a schematic view of a turbocharged ICE system in accordance with a one embodiment of the subject invention. 
           [0026]      FIG. 4A  is a cross-sectional view of a centrifugal compressor parallel to the plane of impeller rotation. 
           [0027]      FIG. 4B  is a cross-sectional view of a centrifugal compressor perpendicular to the plane of impeller rotation. 
           [0028]      FIG. 5A  is a cross-sectional view of a vortex tube adapted for generation of cold output stream only while rejecting heat into a phase change material (PCM). 
           [0029]      FIG. 5B  is a cross-sectional view of a vortex tube adapted for generation of cold output stream only while rejecting heat into a ballast structure. 
           [0030]      FIG. 6  is a schematic view of a turbocharged ICE system in accordance with another embodiment of the subject invention. 
           [0031]      FIG. 7  is a schematic view of a turbocharged ICE system in accordance with yet another embodiment of the subject invention. 
           [0032]      FIG. 8  is a schematic view of a turbocharged ICE system in accordance with still another embodiment of the subject invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    Selected embodiments of the present invention will now be explained with reference to drawings. In the drawings, identical components are provided with identical reference symbols. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are merely exemplary in nature and are in no way intended to limit the invention, its application, or uses. 
         [0034]    Referring to  FIG. 3 , there is shown a turbocharged internal combustion engine (ICE) system  10  in accordance with one embodiment of the subject invention. The ICE system  10  comprises an ICE  20  and a turbocharger assembly  100 . The ICE  20  has at least one combustion chamber fluidly coupled to an intake duct  26  to receive intake air therefrom and to an exhaust duct  46  to discharge exhaust gases thereinto. The type of ICE  20  may be either a compression ignition (diesel), a fuel injected spark ignition, carbureted spark ignition, or homogeneous charge compression ignition (HCCI) also known as controlled auto-ignition (CAI). Furthermore, the ICE  20  may also include an output shaft  28  and a torque sensor  30  for sensing ICE output torque. If the ICE system  10  is installed in an automotive vehicle, the output shaft  28  may provide power to a transmission  74 , which in turn, may spin a drive shaft  48  to operate vehicle wheels  64  via differential  82  and axle  52  as is commonly practiced in the art. 
         [0035]    The turbocharger assembly  100  comprises an exhaust gas turbocharger  162 , a vortex tube  120 , a high-pressure air supply line  138 , control valve  132 , pressure regulator  130 , interconnecting lines  136  and  137 , and an air feed line  148 . The exhaust-gas turbocharger  162  further comprises a compressor  135  having an impeller  123  inside a compressor housing  144  and a turbine  182  having a turbine wheel  170  inside a turbine housing  188 . The impeller  123  and the turbine wheel  170  are mounted on a common shaft  166 . The turbine  182  is fluidly connected to the exhaust duct  46  and adapted to receive therethrough exhaust gases from the ICE  20  to spin the turbine wheel  170 . The compressor housing  144  has an inflow port  158  fluidly connected to inflow duct  126  and an outflow port  174  fluidly connected to intake duct  26 . The compressor  135  is adapted to receive intake air at one pressure through inflow port  158 , to compress it to a higher pressure, and to deliver compressed intake air through outflow port  174  into the intake duct  26  and therethrough to the ICE  20 . The turbocharger assembly  100  may also include an intercooler  168  installed in the intake duct  26  to cool the intake air prior to delivery to the ICE  20 . The turbocharger assembly  100  may also include a speed sensor  114  for sensing rotational speed of the turbocharger  162 . The line  138  is fluidly connected to an auxiliary source of compressed air which may be external to the ICE system  10 . External auxiliary source of compressed air may be an existing supply of compressed air in vehicles such as trucks, buses, earth moving equipment, and utility vehicles. Such an external auxiliary source of compressed air may include a conventional reciprocating or rotary type compressor, or the compressed air may be generated in ICE cylinders during vehicle braking, as for example, disclosed by Larson et al. in U.S. Pat. No. 6,922,997. If an external auxiliary source of compressed air is not used, the turbocharger assembly  100  may also include an auxiliary compressor  164 , compressor inlet line  176 , aftercooler  178 , check valve  180 , air tank  160 , and interconnecting lines  172 ,  184 , and  186 . 
         [0036]    The auxiliary compressor  164  may be of any suitable type and it may have one or more stages to obtain a desired level of compression. Suction port of the auxiliary compressor  164  is fluidly coupled by the inlet line  176  to the intake duct  126  and it is adapted for drawing a portion of intake air therefrom. The auxiliary compressor  164  is preferably driven mechanically, hydraulically or by other suitable means. For example, the auxiliary compressor  164  may be driven mechanically either from the output shaft  28 , or the crankshaft of the ICE  20 , or from the vehicle drive shaft  48 . Suitable mechanical means may include 1) direct coupling and 2) a system of belt and pulleys. Suitable mechanical means may also comprise a clutch  157  or an off-loader valve (not shown) that allows engaging the compressor  164  in accordance with predetermined conditions as it will be described below. Alternatively, the auxiliary compressor  164  may be driven by an electric motor. Discharge port of the auxiliary compressor  164  is fluidly coupled to the air tank  160  via the aftercooler  178 , the check valve  180  and the interconnecting lines  172 ,  184  and  186 . 
         [0037]    The aftercooler  178  may be of the same general type used in conventional compressed air systems to remove the heat of compression from the air downstream of a compressor. The aftercooler  178  may be cooled by ambient air or by ICE coolant or other suitable means. The check valve  180  prevents a backflow of high-pressure air from the air tank  160  into the compressor  164  when the compressor is not operating. The line  184  may also include a water separator to remove water condensate from cooled air flow. The design and choice of materials for the air tank  160  are preferably selected to reduce the likelihood of tank rupture in the event of vehicle collision and/or fire. The air tank  160  may also include a pressure sensor which may be used to determine the amount of air stored. This information may be used in controlling the operation of the auxiliary compressor  164  of turbocharger assembly  100 , and it may be also made available to the operator of an associated automotive vehicle. 
         [0038]    The pressure regulator  130  is fluidly connected to the air tank  160  by means of the high-pressure line  138 . Preferably, the pressure regulator  130  is remotely controllable in a manner that allows remotely controlling the pressure level in the line  136 . Suitable pressure regulators that are remotely controllable either electrically, pneumatically, hydraulically, or mechanically are available commercially. The control valve  132  is fluidly connected to the pressure regulator  130  by means of the line  136  and to the inlet port  116  of vortex tube  120  by means of the line  137 . The control valve  132  may be of on/off type and preferably have a very low flow impedance. Alternatively, the control valve  132  may be adapted for substantially smooth regulation of mass flow rate of compressed air in which case the pressure regulator  130  may become unnecessary. 
         [0039]    The vortex tube  120  is preferably of the type adapted for generation of cold air only such as shown in  FIGS. 2A and 2B  and described in connection therewith. The vortex tube  120  may have a cooling jacket (see  FIGS. 2A and 2B ) which may be cooled by ICE coolant, or by ambient air, or by other suitable means. If ICE coolant is used, it is preferably supplied at a temperature between 5 and 30 degrees Centigrade. Preferably, the body of the vortex tube  120  is maintained at a temperature above zero degrees Centigrade to prevent moisture contained in the air entering the tube from freezing onto tube walls. The design of vortex tube  120  may also include a provision to reduce susceptibility to plugging by ice formed from the residual moisture in the inlet air. Suitable non-freezing vortex tube has been disclosed by Tunkel at al. in U.S. Pat. No. 6,289,679. The inlet port  116  of the vortex tube  120  is fluidly connected to the air tank  160  via the pressure regulator  130 , valve  132 , and the interconnecting lines  136 ,  137 , and  138 . The cold outlet  124  port of the vortex tube  120  is fluidly connected by the air feed line  148  to the compressor housing  144 . The compressor housing  144  is adapted to receive cold air from the feed line  148  and inject it as a jet  146  into the housing  144  via one or more injectors  142 . An alternative vortex tube for use with the subject invention may have a conventional design for concurrent generation of hot and cold outlet stream such as shown in  FIG. 1  and described in connection therewith. In this case, the hot outlet stream may be released from the vortex tube through an appropriate flow impeding device (such as a control valve) so that the cold and hot outlet streams are desirably balanced in volume and a desired cold stream temperature and flow rate are obtained. The ICE system  10  preferably includes an electronic control unit (ECU)  194 . Suitable ECU may be comprised of a central processing unit, a read-only memory, random access memory, input and output ports, and the like. The ECU  194  may be configured to receive signals from sensors in the ICE system  10 , to determine whether certain predetermined conditions exist based on the measured parameters and generate signals to control the operation of the turbocharger assembly  100 . 
         [0040]    Referring now to  FIGS. 4A and 4B , cold air from the air feed line  148  may be injected into the compressor housing  144  through one or more injectors  142   a  to form a jet  146   a  directed into the flow facing portion of the impeller  123  as disclosed by the above noted Sumser. If more than one injector  142   a  is used, they may be circumferentially placed in the inflow port  158 . Alternatively, cold air stream from the air feed line  148  may be injected through one or more injectors  142   b  to form a jet or jets  146   b  directed upstream of the axial end side of the compressor impeller blades  150  and/or one or more injectors  142   c  to form a jet or jets  146   c  directed generally radially at the level of the compressor impeller blades  150  as disclosed by the above noted Scheinert. As a yet another alternative, cold air stream from the air feed line  148  may be injected through one or more injectors  142   d  to form a jet or jets  146   d  directed at the downstream edge of the compressor impeller blades  150  as disclosed by Bucher in U.S. Pat. No. 4,696,165. As a still another alternative, if the compressor  135  has a vaned diffuser  190 , cold air stream from the air feed line  148  may be injected through one or more injectors  142   e  to form a jet or jets  146   e  directed between diffuser blades  196  and into the diffuser inlet as disclosed by the above noted Schegk. In each case, suitable openings for injecting cold air into the compressor housing may be conducive to generating subsonic flow, sonic flow, or supersonic flow. For example, the cold air injector  142   a  through  142   e  may be a subsonic, sonic or supersonic nozzle. 
         [0041]    Referring now again to  FIG. 3 , during normal operation of the supercharged ICE system  10 , intake air stream  32  is drawn into the turbocharger  100 , passes therethrough and it is fed as an intake air stream  32 ″ into ICE  20  where it is combusted with suitable fuel. Exhaust gas stream  92  flows from the ICE  20  through the exhaust duct  46  into the turbine  182  and it exists the turbine  182  as an exhaust gas stream  92 ′. When the ICE  20  operates at reduced load, the amount of exhaust gases in the exhaust stream  92  is limited and the turbocharger  162  may operate at low or moderate rotational speed. Under these conditions, the compressor  135  may generate low or insignificant compression while the engine  20  may be provided with adequate quantity of intake air. Therefore, the control valve  132  may be closed. The auxiliary compressor  164  may be operated concurrently as it may be necessary to maintain the air pressure inside the tank  160  within predetermined limits. In particular, the auxiliary compressor  164  may draw air (preferably free of dust and solid particulates) from the inflow duct  126  through the inlet line  176  and compress it to a desired pressure. Preferred output pressure of auxiliary compressor  164  is between 50 and  300  psi. As an alternative, the auxiliary compressor  164  may draw filtered air from ambient atmosphere or other suitable source. Output of the auxiliary compressor  164  is fed through the line  172  into the aftercooler  178  where the heat of compression is largely removed, and through the line  184 , check valve  180  and line  186  into the air tank  160 . The air tank  160  may be equipped with a pressure switch having one higher setting and one lower setting. The pressure switch may be operatively connected to the controls of the auxiliary compressor  164  (and/or to the clutch  157 , if used) so that the auxiliary compressor  164  may be operated to maintain the pressure in the air tank  160  between predetermined limits. Alternatively, the auxiliary compressor  164  may be equipped with an unloader valve which automatically relieves the auxiliary compressor  164  of the pumping load when the air tank  160  is charged to a predetermined pressure. The auxiliary compressor  164  may be engaged in a smooth and/or gradual manner to avoid imposing abrupt load on its source of motive power. To avoid excessive or unnecessary power drain on the ICE  20 , operation of the auxiliary compressor  164  may be restricted or prohibited during periods of high power demand on the ICE. For example, if the air tank  160  is charged to a level above a predetermined tank charge level value, operation of the auxiliary compressor  164  may be allowed only when the ICE output torque (as, for example, sensed by the torque sensor  30  or by other suitable means) is less than a predetermined ICE output torque value. As another example, if the air tank  160  is charged to a level above a predetermined tank charge level value, operation of the auxiliary compressor  164  may be allowed only when the torque in the vehicle drive shaft  48  is less than a predetermined vehicle drive shaft torque value. Such a predetermined vehicle drive shaft torque value may have a negative sign. The auxiliary compressor  164  may be also engaged in a manner which allows recovery of kinetic energy from the motion of associated automotive vehicle. For example, if the air tank  160  is charged to a level above a predetermined tank charge level value, operation of the auxiliary compressor  164  may be allowed only when vehicle brakes are applied. In this fashion, a significant portion of the vehicle kinetic energy otherwise wasted in braking may be recovered. 
         [0042]    When the demand for output power of the ICE  20  is increased, so is the demand for intake air. At that instant, the speed of the turbocharger  162  may be relatively low and the turbocharger may have to accelerate to meet the ICE intake air demand. This condition is detected as described below and remedied by appropriately setting the pressure regulator  130  and by opening the control valve  132 . As a result, the pressure regulator  130  regulates the pressure of compressed air it receives from the high-pressure supply line  138  and flows regulated compressed air at a predetermined pressure p 1  into the line  136 . The control valve  132  and lines  136 ,  137 , and  148  are preferably constructed to have a very low impedance to air flow. Preferably, output pressure of the pressure regulator  130  is set so that the absolute pressure p 1  at the vortex tube inlet  116  is at least 2.4 times greater than the absolute pressure p 2  inside at the cold outlet port  124 . A preferred value for pressure ratio of p 1 /p 2  is between about 2.4 and about 8. Referenced art suggests that exceeding this range may cause undesirable flow shocks inside the vortex tube  120  (see, e.g., B. K. Ahlbom, supra). With the control valve  132  in an open position, compressed air from the air tank  160  forms a stream  110  which flows through the line  137  to the inlet port  116  of the vortex tube  120 . If the vortex tube shown in either  FIG. 2A  or  2 B is used, thermodynamic action inside the vortex tube deposits heat into the tube&#39;s cooling jacket and it cools the air inside the tube. Regardless of the vortex tube style, cold air exits the vortex tube  120  through the cold outlet port  124 , flows through the air feed line  148  into the compressor housing  144  via the injector  142  and it forms a jet  146 . 
         [0043]    Referring now again to  FIGS. 4A and 4B , the injector  142  may be arranged in the configuration of injector  142   a ,  142   b ,  142   c ,  142   d , and/or  142   e . One or more injectors may be used for each injector configuration. In particular, cold air stream from the air feed line  148  may be injected 1) through one or more injectors  142   a  to form one or more jets  146   a  directed into the flow facing portion of the impeller  123  and/or 2) through one or more injectors  142   b  to form one or more jets  146   b  directed upstream of the axial end side of the compressor impeller blades  150  and/or 3) through one or more injectors  142   c  to form one or more jets  146   c  directed onto the compressor impeller blades  150  and/or 4) through one or more injectors  142   d  to form one or more jets  146   d  directed at the downstream edge of the compressor impeller blades  150 . The impeller  123  of compressor  135  is thus cooled by contact with injected cold air and the momentum of the injected air is in-part transferred to the impeller  123 , thereby accelerating its rotational speed. If the compressor  135  has a vaned diffuser  190 , cold air stream from line  148  may be injected through one or more injectors  142   e  to form one or more jets  146   e  directed between the diffuser blades  196  and into the diffuser inlet. The resulting jets  142   e  entrain intake air in the diffuser and pump it into the intake duct  26 . Cold air injected through any of the injectors  142   a  through  142   e  is mixed with the intake air stream  32  and, as a result, cooler and denser air is delivered into the intake duct  26 . Air flowing through the intake duct  26  may be further cooled by the intercooler  168  prior to being delivered the combustion chambers of ICE  20 . Increased quantity of air available for combustion allows ICE  20  to generate more output power and greater quantity of exhaust gases in the exhaust gas stream  92  which, in turn, operates the turbine wheel  170  and allows it to further accelerate in rotational speed. 
         [0044]    Under typical driving conditions the periods of high-power demand on the ICE  20  are relatively short and (depending on vehicle driving conditions) may occur on the average only about 10% of the vehicle operating time. This means that the conditions requiring the turbocharger  100  to accelerate may be discontinuous and air from the air tank  160  may be discharged in an intermittent mode. For example, the ICE may operated in a supercharged mode for about 10% of the vehicle operating time. This may leave on the average about 90% of the vehicle operating time available for recharging the air tank  160 . 
         [0045]    At any time during the ICE operation, the ECU  194  may monitor one or more operating parameters of the ICE system  10  and regulate the mass flow rate of air through the vortex tube  120  by operatively controlling the pressure regulator  130  and the valve  132  according to predetermined conditions. Operating parameters monitored by the ECU  194  may include engine rotational speed, turbocharger rotational speed, engine output torque, fuel flow rate, vehicle speed, throttle opening (if throttle is used), and position of accelerator pedal. Other useful parameters monitored by the ECU may include ambient air pressure and temperature, intake air mass flow rate, and intake air pressure and temperature. The engine output torque value can be either directly measured (for example, the torque value can be the detection value of the torque sensor  30 ) or it can be inferred from other ICE parameters. In particular, it is well known that engine torque value can be estimated from one or more ICE parameters including intake air mass flow rate, spark timing, or combustion chamber pressure data as noted, for example, by T. Jaine et al. in “High-Frequency IMEP Estimation and Filtering for Torque-Based SI Engine Controls,” SAE paper number 2002-01-1276, published by the Society of Automotive Engineers, Inc., Warrendale, Pa. Alternatively to using an ECU with a central processing unit, various electrical, mechanical, electromechanical, hydraulic, and/or pneumatic control mechanisms may be used to operate the valve  132  and the pressure regulator  130  in response to predetermined conditions. It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the ECU can be any combination of hardware and software that will carry out the functions of the present invention. 
         [0046]    There is a variety of processes the ECU  194  may employ for controlling the operation of the turbocharger  100 . Preferably, the ECU repeatedly obtains and stores detection values of various sensors which may be processed to determine the state of ICE system  10 . Such sensors may include, but are not limited to ICE rotational speed, turbocharger rotational speed, position of accelerator pedal, throttle opening, fuel flow rate, vehicle speed, ICE output torque, air velocity in the intake duct  26 , air pressure in the line  137 , setting of the pressure regulator  130 , position of the control valve  132 , air pressure and temperature in the intake duct  126 , air pressure and temperature in ICE intake duct  26 , ambient air pressure and temperature, and pressure and temperature of exhaust gases in the exhaust duct  46 . The ECU  194  may be configured to increase the mass flow of cold air into the compressor housing  135  if simultaneously the turbocharger rotational speed value is less than a predetermined turbocharger rotational speed value and the ICE torque value is more than a predetermined ICE torque value. Accordingly, the ECU  194  may be configured to decrease the mass flow of cold air into the compressor housing  144  if simultaneously the turbocharger rotational speed value is more than a predetermined turbocharger rotational speed value and the ICE torque value is less than a predetermined ICE torque value. 
         [0047]      FIGS. 5A and 5B  respectively show alternative vortex tubes  120 ′ and  120 ″ suitable for use with the subject invention. Referring now to  FIG. 5A , the vortex tube  120 ′ comprises a tubular body  252  having two ends  214  and  215  opposite to each other. The first end  215  is entirely closed. The second end  214  is partially closed and has a central opening  244  leading to a cold outlet port  124 . An inlet port  116  for compressed air is installed in proximity of the second end  214 . The tubular body  252  is preferably constructed from a material with high thermal conductivity such as copper, copper alloys, aluminum and aluminum alloys. Exterior of the tubular body  252  is substantially surrounded by a cooling jacket  262  filled with phase change material (PCM)  218 . Suitable PCM may include stearin which is known to have a transition temperature in the range of 50-70 degrees Centigrade and certain fusible metals such as Wood&#39;s metal which is known to have a transition temperature around 70 degrees Centigrade or Field&#39;s metal which is known to have a transition temperature around 62 degrees Centigrade. The vortex tube  120 ′ may also include cooling fins  216  attached to the exterior surface of tubular body  252 . Suitable cooling fins are preferably made of material with high thermal conductivity and are in a good thermal contact with each the tubular body  252  and the PCM  218 . In one embodiment, the cooling fins  216  may extend radially so as to protrude through the cooling jacket  262  (as shown in  FIG. 5A ). Tip portions  286  of cooling fins  216  may be in a thermal communication with a cooling fluid which may be a gas such as air or a liquid such as engine cooling fluid. 
         [0048]    The vortex tube  120 ′ is suitable for operation in two modes: 1) a cooling mode and 2) a thermal recovery mode. At the beginning of the cooling mode, the PCM  218  is substantially in a solid form. Compressed air stream  110  at an initial pressure and temperature is injected through the inlet port  116  tangentially into the interior of the tubular body  252  where it forms a vortex flow pattern in a manner already described in connection with  FIGS. 1 ,  2 A and  2 B. Furthermore, the injected air is cooled and it forms a cold air stream  151  having reduced temperature and pressure. The cold air stream  151  exits the vortex tube  120 ′ through the central opening  244  leading to the cold outlet port  124 . The vortex flow deposits heat into the tubular body  252 . The tubular body  252  further conducts the heat with the aid of the cooling fins  216  into the PCM  218  and causes it to gradually melt. When the PCM  218  is substantially melted, the cooling mode may be terminated, the flow of compressed air stream  110  is stopped, and the thermal recovery mode may be initiated. In the thermal recovery mode of operation, heat stored in the PCM  218  may be removed from the vortex tube  120 ′ by conducting it through the cooling fins  216  to a coolant in thermal communication with the tip portions  286 . When the PCM  218  has been substantially transformed back into solid form, the thermal recovery mode of operation may be concluded and the vortex tube  120 ′ may be ready for operation in the cooling mode. 
         [0049]    The vortex tube  120 ″ shown in  FIG. 5B  uses a heat ballast structure  212  to store thermal energy as sensible heat. The ballast structure  212  is preferably made of material having high thermal conductivity, such as aluminum alloys or copper and it is placed in a good thermal communication with the tubular body  252 ′. Furthermore, the ballast structure  212  may include fins  228 . In some variants of the invention, the ballast structure  212  and the tubular body  252 ′ may be formed as a single component. The vortex tube  120 ″ is suitable for operation in two modes: 1) a cooling mode and 2) a thermal recovery mode. At the beginning of the cooling mode, the temperature of the ballast structure  212  is less than a predetermined ballast lower temperature value. As the vortex tube  120 ″ cools injected compressed air, the tubular body  252 ′ conducts heat to the ballast structure  212  causing it to gradually heat up. When the temperature of the ballast structure  212  reaches a predetermined ballast upper temperature value, the cooling mode may be terminated, the flow of compressed air stream  110  may be stopped, and the thermal recovery mode may be initiated. In the thermal recovery mode of operation, heat stored in the ballast structure  212  may be removed from the vortex tube  120 ″ by conducting it through the cooling fins  228  to a coolant in thermal communication with the cooling fins. When the temperature of the ballast structure  212  becomes less than a predetermined ballast lower temperature value, the thermal recovery mode of operation may be concluded and the vortex tube  120 ″ may be ready for operation in the cooling mode. As already noted, the cooling fins of the vortex tubes  120 ′ and  120 ″ may be cooled by air. If the ICE  20  is water cooled and it has a radiator with a fan that induces air into the radiator, or if the ICE  20  is air cooled and it has a fan that induces air over the engine, the vortex tube may be placed so that it may receive a part of the air flow induced by the fan. If the ICE is used in a vehicle, the vortex tube  120 ′ or  120 ″ may be exposed to vehicle slipstream air and be cooled by it. 
         [0050]    Referring now to  FIG. 6 , there is shown a turbocharged ICE system  11  in accordance with another embodiment of the subject invention which is particularly suitable for turbochargers with high compression ratio and for substantially continuous operation. The ICE system  11  comprises a turbocharger assembly  101  which is essentially the same as the turbocharger assembly  100  except that the source of compressed air for operation of the vortex tube  120  in this embodiment may be the compressor  135 . Furthermore, the pressure regulator  130  may not be used. In particular, the inlet port  116  of vortex tube  120  is fluidly coupled to the intake duct  26  by means of the line  136 ′. The line  136 ′ is fluidly connected to the intake duct  26  preferably downstream of the intercooler  168  (if intercooler is used). The compressor  135  used in this embodiment should be capable for generating sufficiently high pressure ratio to operate the vortex tube  120 . Preferably, the compressor pressure ratio is at least 2.4. Alternatively, a second compressor  128  (shown in broken line) may be placed in series with and downstream of the compressor  135 . In such case, the line  136 ′ is preferably arranged to receive compressed air generated by the second compressor  128 . The injector  142  may be configured in the form of an injector  142   a ,  142   b ,  142   c , and/or  142   d  as shown in  FIGS. 4A and 4B  and already described in connection therewith. The control valve  132  may be configured upstream of the vortex tube  120  (as shown in  FIG. 6 ) or down stream of it (in line  148 ). In either case, the control valve  132  may be adapted for substantially smooth control of mass flow rate of cooled air to the injector  142 . If desirable, the air feed line  148  may be branched out and separate control valves may be configured on each branch to independently control delivery of cold air from the vortex tube  120  to the injectors  142   a ,  142   b ,  142   c , and/or  142   d.    
         [0051]    In operation, compressor  135  may receive intake air stream  32 , compress it to generate compressed intake air stream  32 ′ which may be compressed again by the second compressor  128  (if used) and feed it to the intercooler  168  thereby producing an intake air stream  32 ″ which may be then fed to the ICE  20 . Intake air may be combusted with suitable fuel in ICE  20  thereby generating an exhaust gas stream  92  which may be fed to the turbine  174  to spin the turbine wheel  170 , which in turn may spin the impeller  123  of compressor  135 . When injection of cold air into the housing  144  of compressor  135  is desired, the valve  132  may open at least partially and a portion of the intake air stream  32 ″ may be allowed to flow into the line  136 ′, through the control valve  132  and into the line  137 , thereby forming a compressed air stream  110 ′. The air stream  110 ′ may flow through the inlet port  116  into the vortex tube  120  where it may be at least in-part cooled and then fed through the air feed line  148  into the housing  144  of compressor  135 . The turbocharger assembly  101  is particularly suitable for use with a turbocharger  162  having a compressor capable of generating high output pressure or an ICE system having multiple charge compressor stages. The turbocharger assembly  101  is also particularly suitable for substantially continuous operation whenever the pressure in the intake duct  26  is sufficient to operate a vortex tube. 
         [0052]    Referring now to  FIG. 7 , there is shown a supercharged ICE system  12  in accordance with a yet another embodiment of the subject invention and having additional capability to provide dense intake air during periods of increasing power demand on the ICE  20 . The ICE system  12  comprises a turbocharger assembly  102  which is similar to the turbocharger assembly  100  except that the cold outlet port  124  of the vortex tube  120  is connected by the air feed line  148 ′ to the intake duct  26  rather than to the compressor housing  144 . Furthermore, the air feed line  148 ′ is preferably terminated inside the intake duct  26  with a driving nozzle  140  which is arranged to inject air in the general direction of the intake air stream  32 ″. One driving nozzle or several driving nozzles configured in parallel may be used. Suitable types of driving nozzles include a simple orifice, a subsonic nozzle, a sonic nozzle, supersonic nozzle, converging-diverging nozzle, and a lobed nozzle. Several configuration of a suitable supersonic nozzle are disclosed in the already noted Applicant&#39;s co-pending U.S. patent application Ser. No. 11/389,795. Preferred nozzle types include a converging-diverging nozzle which is conducive to generating supersonic flow and/or a lobed nozzle which is known for its good mixing characteristics. Note that a lobed nozzle may be operated in a supersonic flow regime. The nozzle  140  may also have a variable throat area for control of mass flow rate therethrough. Examples of suitable variable area driving nozzles have been disclosed in Applicant&#39;s U.S. Pat. No. 7,076,952 and the already noted co-pending U.S. patent application Ser. No. 11/655,441. To operate the driving nozzle  140  in the supersonic regime, the nozzle pressure ratio (=pressure in the line  148 ′/pressure in the intake duct  26  downstream of the nozzle) should be at least about 1.9. In addition, the flow rate and pressure of air fed in the line  137  into the inlet port  116  of vortex tube  120  should be properly selected so that the ratio of pressure at the vortex tube inlet  116  to the pressure at the cold outlet port  124  is maintained preferably between about 2.4 and about 8 as already stated above. 
         [0053]    In operation, when the ICE  20  is experiencing increasing power demand and the turbocharger  162  rotates at a speed insufficient to provide adequate amount of intake air to the ICE, the control valve  132  may open and cold air from the vortex tube  120  may be injected through the driving nozzle  140  into the intake duct  26 . The driving nozzle  140  generates a high velocity jet  146 ′ of cold air, which mixes with and entrains the intake air inside the intake duct  26 , and forces the intake air toward the ICE  20 . Kinetic energy of the flow downstream of the nozzle  140  is gradually converted into a potential (pressure) energy. As a result, intake air pressure inside the intake duct  26  downstream of the nozzle  140  is greater than the pressure upstream of the nozzle  140 , and the air temperature downstream of the nozzle  140  is lower than the temperature upstream of the nozzle  140 . Another words, injection of cold high-velocity air through the nozzle  140  increases the density of intake air fed to the combustion chamber of ICE  20  by a combination of compression and cooling. Cold air injection into the intake duct  26  may be also initiated whenever 1) the temperature of intake air downstream of the intercooler  168  exceeds a predetermined intake air temperature value, or 2) whenever the temperature of exhaust gas stream  92  exceeds a predetermined exhaust gas stream temperature value and the engine speed is less than a predetermined engine speed value, or whenever 3) the rate of temperature increase of intake air downstream of the intercooler  168  exceeds a predetermined rate of temperature increase of intake air value and the engine speed is less than a predetermined engine speed value, or 4) whenever the rate of increase of exhaust gas stream  92  temperature exceeds a predetermined rate of increase of exhaust gas stream  92  temperature value and the engine speed is less than a predetermined engine speed value. 
         [0054]    A portion of the intake duct  26  in the vicinity of the nozzle  140  may be formed into a venturi shaped diffuser duct  134  indicated in broken line in  FIG. 7 . Such an arrangement enhances the capability of the nozzle  140  to pump intake air. The diffuser duct  134  preferably has a circular cross-section which is known for its low wall friction losses. However, other cross-sections including oval, ellipse, square, rectangle, polygonal shape, and alike may be also used. The diffuser duct  134  preferably has an upstream converging section, which may be followed by a straight middle section that is followed by a downstream divergent section. It should be noted that the nozzle  140  together with the venturi shaped diffuser duct  134  may be regarded as an ejector. Performance of such an ejector, namely its throughput and compression ratio depend (among other things) on the configuration of the nozzle  140  and of the diffuser  134 . For an ejector used in ICE supercharging application, it is desirable that the ejector (a) is capable of producing a compression ratio comparable to mechanical superchargers and turbochargers, namely at least about 1.3 and preferably at least about 1.5, (b) presents relatively low impedance to intake air flow when the ejector is not operating, and (c) is compact. Compactness is very important in automotive applications, especially in passenger automobiles, where the space in the engine compartment is very limited. In a practical sense, compactness of the ejector is mainly affected by the length of the diffuser duct. The above desirable attributes may be in mutual conflict because improving one may make it more challenging to meet the others. For example, to avoid undesirable detachment of flow from the diffuser wall, the walls of the diverging portion of the diffuser may be sloped at a very small angle (typically not exceeding about 4 degrees) with respect to the nominal flow direction. The length of the diffuser duct thus increases with the increasing transverse dimension (e.g., diameter) of the diffuser duct throat. One may increase the transverse dimension of a diffuser duct throat and thus beneficially reduce its impedance to intake air flow when the ejector is not operating (assuming that such flow passes through the ejector). However, a diffuser duct with a larger throat may make it more challenging to obtain a desired compression ratio. The approaches to making the ejector acceptably compact (short) while achieving acceptably high compression and acceptably low impedance to intake air flow may include: 1) use of lobed driving nozzle, 2) use of multiple driving nozzles, 3) use of multiple parallel ejectors, 4) use of a variable area diffuser, and 5) use of an ejector bypass duct. These will be now described in detail. 
         [0055]    1) Lobed nozzles have been developed in aeronautics to improve mixing of the surrounding air with the high velocity jet produced by jet engines. Lobed nozzles may be operated either in a subsonic or supersonic regime. Suitable lobed nozzle is described in connection with jet engine design in a variety of technical publications including, for example, in “Parameter Effects on Mixer-Ejector Pumping Performance” by S. A. Skebe et al., paper number AIAA-88-0188 and in “Short Efficient Ejector Systems” by W. Pretz, Jr. et al., paper number AIAA-87-1837, both of which are available from the American Institute of Aeronautics and Astronautics, Washington, D.C., and in “Supersonic Nozzle Mixer Ejector,” by T. G. Tillman et al. published in Journal of Propulsion and Power, Volume 8, Number 2, March-April 1992, pages 513-519, and “Supersonic-Ejector Characteristics Using Petal Nozzle,” by A. K. Narayanan et al., published in Journal of Propulsion and Power, Volume 10, Number 5, September-October 1994, pages 742-744. The use of lobed nozzle in ejectors for ICE supercharging of has been disclosed by the Applicant in the already noted U.S. Pat. No. 7,076,952. The use of lobed driving nozzle may allow constructing a supercharging ejector with a substantially shorter diffuser than a comparable ejector with a single non-lobed driving nozzle. If the throat area of an associated diffuser duct is made about 25 to about 50 times the throat area of the corresponding lobed driving nozzle, the diffuser duct should have an acceptable impedance to intake air flow when the ejector is not operating. However, this condition may make it more challenging to obtain a desired compression ratio. 
         [0056]    2) Ejector with multiple nozzles: An ejector having multiple driving nozzles discharging into one diffuser (as disclosed by the Applicant in the already noted U.S. Pat. No. 7,076,952) may be also made substantially (generally about 30%) shorter than a comparable ejector having a single nozzle without excessive degradation in performance. If the throat area of an associated diffuser duct is made about 25 to about 50 times the sum of the throat areas of the corresponding multiple driving nozzles, the diffuser duct should have an acceptable impedance to intake air flow when the ejector is not operating. However, this condition may make it more challenging to obtain a desired compression ratio. 
         [0057]    3) Multiple parallel ejectors: Instead of one larger capacity (and comparably longer) ejector, one may use several smaller capacity (and comparably shorter) ejectors fluidly connected in parallel as disclosed by the Applicant in the already noted co-pending U.S. patent application Ser. No. 11/389,795. If for each of the smaller ejectors the throat area of an associated diffuser duct is made about 25 to about 50 times the throat area of the corresponding driving nozzle, the combination of parallel diffuser ducts should have an acceptable impedance to intake air flow when the ejector is not operating. However, this condition may make it more challenging to obtain a desired compression ratio. 
         [0058]    4) The diffuser duct  134  may be also constructed as a variable area diffuser duct as disclosed by the Applicant in the already noted co-pending U.S. patent application Ser. No. 11/389,795. When the nozzle  140  injects high-velocity air into the variable area diffuser duct, the throat area of diffuser duct  134  may be set to between about 2 to about 25 times the throat area of the driving nozzle  140  (or the combined throat areas of multiple driving nozzles if multiple driving nozzles are used) to achieve high compression. In particular, the throat area of a variable area diffuser duct is preferably set to 3 to 15 times (and most preferably to 5 to 10 times) the throat area of the driving nozzle (or the combined throat areas of multiple driving nozzles if multiple driving nozzles are used). When the nozzle  140  is not operating, the throat area of the variable diffuser duct may be set to more than about 25 times (and preferably more than 50 times) the area of the driving nozzle  140  (or the combined throat areas of multiple driving nozzles if multiple driving nozzles are used) to achieve acceptable impedance to intake air flow. 
         [0059]    4) Ejector bypass duct. A bypass duct offers a convenient low impedance means for flowing at least a portion of intake air when the ejector is not operating. Referring now to  FIG. 8 , there is shown a supercharged ICE system  13  in accordance with a still another embodiment of the subject invention and having additional capability to provide dense intake air during periods of increasing power demand on the ICE  20 . The ICE system  13  comprises a turbocharger assembly  103  which is essentially the same as the supercharger assembly  102  except that nozzle  140  and the diffuser duct  134  are now a part of an ejector pump  122 . In addition, the turbocharger assembly  103  includes a bypass duct  190 , which allows the flow of intake air from the compressor  135  to bypass the ejector pump  122 . The bypass duct  190  includes a bypass valve  188  for control of intake air passing therethrough. The ejector pump  122  may be practiced with multiple driving nozzles injecting high-velocity jet into a single diffuser duct. Alternatively, several ejector pumps  122  may be used in parallel. As another alternative, one or more lobed driving nozzles may be used. The driving nozzle  140  may be also a variable area nozzle. Regardless of the driving nozzle configuration, the throat area of diffuser duct  134  may be made between about 2 to about 25 times the throat area of the driving nozzle  140  (or the combined throat areas of multiple driving nozzles if multiple driving nozzles are used) to achieve high compression. In particular, the throat area of the diffuser duct  134  is preferably made 3 to 15 times (and most preferably to 5 to 10 times) the throat area of the driving nozzle (or combined throat area of multiple driving nozzles if multiple driving nozzles are used). Three Penberthy ejectors model numbers GL-½, GL-¾, and GL-1¼″ (made by Penberthy Inc., Prophetstown, Ill.) with the throat areas of the diffuser ducts respectively being about 7.2 times, 7.5 times, and 6.3 times the throat areas of their respective driving nozzles were tested and showed acceptable compression and pumping performance. 
         [0060]    The bypass valve  188  may be formed as a check valve that closes automatically whenever the pressure downstream of the ejector  122  significantly exceeds the pressure upstream of the ejector  122 . Alternatively, the bypass valve  188  may an actuated valve of a suitable type (e.g., gate valve, poppet valve, damper valve, or a butterfly valve) operated by the ECU  194 . For example, the ECU  194  may close the bypass valve  188  whenever the mass flow through the driving nozzle  140  exceeds a predetermined mass flow value. Conversely, the ECU  194  may open the bypass valve  188  whenever the mass flow through driving nozzle  140  is below a predetermined mass flow value. If the valve  188  is an actuated valve, its closing and opening rate can be coordinated with the value of mass flow rate of air through nozzle  140  to produce a substantially smooth variation in air density at the ICE intake passage  26 . This approach is intended to avoid undesirably abrupt changes in ICE power output. Suitably precise control of valve  188  may be accomplished, for example, by actuating the valve  188  by a stepping motor. In operation, when it is not desirable to flow cold air through nozzle  140  the control valve  132  may be closed. Concurrently, the bypass valve  188  may be in an open position and intake air may flow primarily through the bypass duct  190 . When injection of cold air through nozzle  140  is desired, the control valve  132  may be open, the ejector pump  122  may be operated and the bypass valve  188  may be closed. 
         [0061]    It will be appreciated that the present invention can be implemented with a variety of ICE of either reciprocating type or rotary type. The ICE can have any number of combustion chambers. Features of the various embodiments may be combined in any suitable manner. The turbocharger assembly  100 ,  101 ,  102 , and  103  may be practiced with any type of a compressor  135  having an impeller  123 , including a turbo-compressor driven by an exhaust gas turbine or by an electric motor. The compressor  135  may have a radial or axial configuration. The turbocharger assembly  102  and  103  may be also practiced with the compressor  135  replaced by a suitable mechanical compressor including a Roots pump, screw compressor and a scroll compressor, or the turbocharger assembly may be practiced without the compressor  135 . 
         [0062]    An ICE system may be also incorporate several combined embodiments the turbocharger assembly of the subject invention and such embodiments may be activated according to predetermined conditions. For example, in response to increasing power demand and with the turbocharger  162  providing insufficient intake air, an ICE system may be initially configured in accordance with the turbocharger assembly  102  or  103 , wherein compressed air from an auxiliary source of compressed air is cooled in a vortex tube  120  and the resulting cold air injected into the intake duct  26 . After the injection of cold air into the intake duct  26  has been initiated, the ICE system may be configured in accordance with the turbocharger assembly  100 , wherein compressed air from an auxiliary source of compressed air is cooled in the vortex tube  120  and the resulting cold air injected into the compressor housing  144  where it may be used to favorably shift the surge limit, and/or to accelerate the rotational speed of compressor impeller  123 , and/or to cool the impeller blades  150 , and/or to produce pumping action in the diffuser  190  (if the diffuser is present). Once the compressor  135  has reached its normal operating rotational speed range, the ICE system may be configured in accordance with the turbocharger assembly  101 , wherein a portion of the compressed intake air stream downstream of the compressor  135  is separated, cooled in the vortex tube  120  and injected into the compressor housing  144  where it may be used to favorably shift the surge limit, and/or accelerate the rotational speed of compressor impeller  123 , and/or to cool the impeller blades  150 , and/or to produce pumping action in the diffuser  190  (if the diffuser is present). 
         [0063]    The term “intake air” used in this application should be give an broad interpretation so as to include presence of ICE fuel and ICE exhaust gases. Thus, intake air is essentially a mixture of nitrogen, oxygen, carbon dioxide, water vapor, and inert gases, and may also include ICE fuel vapor, nitrogen oxides, and hydrocarbons. In some embodiments of the invention the compressed air for operation of the vortex tube may be derived from the intake air, therefore, the composition of the compressed air may be essentially the same as that of the intake air. 
         [0064]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” and “includes” and/or “including” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0065]    The terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies. 
         [0066]    Moreover, terms that are expressed as “means-plus function” in the claims should include any structure that can be utilized to carry out the function of that part of the present invention. In addition, the term “configured” as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function. 
         [0067]    While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the present invention as defined in the appended claims. Furthermore, the foregoing description of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the present invention as defined by the appended claims and their equivalents. Thus, the scope of the present invention is not limited to the disclosed embodiments.