COMPRESSOR HOUSING FOR A TURBOCHARGER AND A METHOD OF PRODUCING SUCH HOUSING

Abstract: A compressor housing with a tubular shaped inlet port (40) having a transverse wall attached to one end of the inlet port (40) and extending outwardly therefrom, a circumferen­ tial chamber (44) formed in the wall opposite the inlet port (40) and provided with a circumferential opening substantially in the plane of the wall, and an opening which communicates with the intake manifold of the engine to which the tur­ bocharger is attached contains a wall insert (126) which has a tubular throat (128) with a circular disc (130) attached at one end of the tubular throat transverse thereto. The disc (130) has an aperture corresponding to the opening formed by the tubu­ lar throat (128). The inlet (40) is formed with an inside surface having a first portion (110) remote from the disc (130) with a varying diameter converging toward the disc (130) and a sec­ ond portion (112) adjacent the disc (130) The tubular throat (128) has an inside surface (131) converging in diameter toward the disc (130) and an outside surface (132) diverging in diameter toward the disc (130) to mate with the diverging inner surface of the inlet port (40).

Description: TURBOCHARGER HOUSING AND A METHOD OF PRODUCING SUCH HOUSING The present invention relates to turbocharger housing and a method of producing such housing. The present design and method of production of prior art compressor housings for turbochargers have presented a considerable problem. Centrifugal flow compressors are one of the most widely used dynamic compressors in turbochargers. In this compressor type, air or an air-fuel mixture enters the compressor inlet, is channeled to the compressor rotor and is accelerated to near sonic speeds at a right angle to the inlet flow path. Increase in air pressure is accomplished by reducing the velocity of the accelerated gases as discharged from the tip of the compressor rotor blades. This process, known as diffusion, is more efficiently achieved by slowiny down the gases without turbulence so that a large percentage of the velocity energy is converted into pressure energy, raising the static pressure. To facilitate this diffusion process, turbochargers employing centrifugal compressors have normally included a compressor rotor wall closely following the contour of the compressor rotor blades from the blade leading edge to its outer tip. This compressor wall then extends past the outer tip of the blade to form one of two walls of the diffuser, then terminates to provide a circumferential gap through which the compressed gases are channeled into a circumferential chamber leading to the intak manifold of the engine. This wall, facing the compressor rotor blades and closely contoured to the rotor blades then extending outward, uniformly decreases the velocity of the gases after the gases leave the rotor blades and prior to their entry into the chamber leading to the engine. Thus, this wall structure greatly increases the static pressure yenerated by the compressor. To form this structure, most turbocharger compressor housings have been sand-cast with the compressor wall cast in one piece with the compressor outer surround housing. This has normally been accomplished by using a sand core to form the circumferential chamber leading to the intake manifold of the engine. After casting, this sand core is dislodged to produce the chamber on the opposite side of the wall from the compressor in which gases are channeled off of the tips of the compressor rotor. Although die-casting of the compressor housing would be substantially less expensive and more accurate than sand-casting, die-casting of an optimum design has not been possible because of the inability to use die-cast molds to form the circumferential chamber which channels the compressed gases to the intake manifold of the engine and at the same time form the diffuser wall. Because the variable area chamber is necessarily larger than the inlet gap through which gases are injected from the compressor rotor bldes, die-casting an optimum design compressor housing has not been possible because of the inability to design molds that would form this passageway behind the wall facing the blades of the compressor rotor. Where die-cast compressor housings are used, the wall normally formed in sand-cast compressor housings is merely deleted so that the molds may be brought together and parted to form the casting. However, without this wall, gases accelerated by the compressor rotor are prematurely dumped from the diffuser into the circumferential chamber leading into the engine intake manifold. As a result, this arrangement realizes a substantially lower compressor efficiency and thus lower performance. It is an object of the invention to provide for a turbocharger housing with a compressor wall which can be produced by die-casting. The compressor rotor housing unit according to the invention includes a compressor housing and a compressor wall insert for mating with the compressor housing. The compressor housing includes a tubular shaped inlet port having a transverse wall attached to one end of the tubular port and extending outwardly therefrom. A circumferential chamber is formed in the wall opposite the inlet port and has a circumferential opening substantially in the plane of the wall. The circumferential chamber also has an opening which communicates with the intake manifold of the engine to which the turbocharger is attached; The wall insert is formed having a tubular throat with a circular disc attached at one end of the tubular throat transverse thereto. The disc has an aperture corresponding to the opening formed by the tubular throat. Rivet-like protrusions are integrally formed and extend from the disc corresponding to and facing apertures formed in the wall of the compressor housing. These protrusions are circumferentially spaced around the tubular throat and correspond in position to the apertures formed around the inlet port in the transverse wall of the compressor housing. The protrusions engage the apertures to join the insert to the compressor housing such that the circular disc forms a forward diffuser wall of the turbocharger. The tubular throat of the insert fits within the inlet port allowing the circular disc to abut the transverse wall of the compressor housing for engagement thereto. The disc extends beyond the transverse wall and partially encloses the opening in the plane of the wall of the circumferential chamber. In accordance with one embodiment of the invention, the inlet port is formed with an inside surface having a first portion remote from the transverse wall with a varying diameter converging toward the wall and a second portion adjacent the compressor housing transverse wall diverging in diameter toward the wall. The tubular throat of the wall insert has an inside surface converging in diameter toward the circular disc and an outside surface diverging in diameter toward the disc to mate with the diverging inner surface of the inlet port of the compressor housing. The inner surface of the throat portion of the wall insert converges at substantially the same rate as the inlet port inner surface to form a continuous converging surface from the opening into the inlet port to the area adjacent the insert disc where the compressor rotor is positioned. As is now appreciated, the compressor housing unit consists of two components which are cast separately and joined to form the completed unit. By so doiny, the components are designed so that they may be die-cast while still providing a forward diffuser wall for closing the circumferential chamber except for an annular gap through which compressed air is channeled from the blade tips of the compressor rotor. In accordance with another embodiment of the invention, the housing unit further includes a bearing support cylinder positioned from the inner wall of the inlet port by a plurality of vanes extending from the inner wall. The vanes are aligned to be substantially radial from the center line of the inlet port with a leading edge facing the opening to the inlet port and a trailing edge substantially opposite the leading edge. The leading and trailing edges are separated by thicker intermediate vane sections. In accordance with still another embodiment of the invention, one end of the tubular throat of the compressor wall insert is notched to correspond with the vanes such that the throat straddles the vanes when the tubular throat is inserted within the inlet port. In accordance with still another embodiment of the invention, a turbocharger having a compressor rotor and turbine rotor mounted for rotation on a shaft supported in a housing forming an inlet to the compressor rotor includes a concentrically positioned cylindrical module mounted within the inlet upstream of the compressor rotor and supported from the inlet wall by struts extending from the inlet wall to the cylindrical module. The struts divide the inlet into more than one inlet passage. The compressor inlet has a converging inner wall from the mouth of th inlet to the compressor rotor. The struts are formed with a leading and trailing edge thinner than the portion of the strut intermediate thereof. The inlet diameter is shorter than the length of the inlet. In a more specific embodiment of the invention, three struts extend substantially radially from the cylindrical module to the side wall of the inlet and divide the inlet into three inlet passages. It has been found that this inlet structure substantially eliminates the surge area normally encountered by conventional turbochargers at low compressor flows and allows the turbocharger to continue to function at low compressor flows and corresponding low engine speeds without producing unstable flow at low operating speeds. For a more complete understanding of the present invention, and for further details and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which: FIGURE 1 is a perspective view of the turbocharger of the present invention; FIGURE 2 is a vertical section taken along lines 2-2 of the turbocharger illustrated in FIGURE 1; ; FIGURE 3 is an exploded perspective view showing the two components of the compressor housing unit separated from molds used to make the components, FIGURE 4 is a frontal view looking into the inlet port of the turbocharger illustrated in FIGURE 1, FIGURE 5 is a section view taken along.line 5-5 of FIGURE 4, FIGURE 6 is a section view taken along line 6-6 of FIGURE 4, FIGURE 7 is a section view taken along line 7-7 of FIGURE 4, FIGURE 8 illustrates an alternative'embodiment of the present invention wherein the forward diffuser wall is modified to modify the turbocharger characteristics, FIGURE 9 illustrates a compressor performance map for a conventional turbocharger, FIGURE 10 illustrates a compressor performance map for the turbocharyer illustrated in FIGURES 1-8; ; FIGURE 11 illustrates a vertical section of an alternative embodiment of the turbocharger of FIGURES 1-8; FIGURE 12 illustrates a vertical section of the turbocharger illustrated in FIGURES 1-8 mounted on a 1,V11 engine; FIGURE 13 is a top plan view of the assembly illustrated in FIGURE 12; FIGURE 14 illustrates a vertical section of the turbocharger of FIGURES 1-8 mounted on an in-line engine; FIGURE 15 is a top plan view of the assembly illustrated in FIGURE 14; FIGURE 16 illustrates a vertical section of the upper half of a turbojet in accordance with the present invention; FIGURE 17 illustrates a vertical section of a turbofan in accordance with the present invention; FIGURE 18 illustrates a vertical section of the upper half of an alternative embodiment of the turbojet illustrated in FIGURE 16; ; FIGURE 19 is a section view taken on line 19-19 of FIGURE 18; FIGURE 20 illustrates a vertical section showiny the upper half of a turbofan according to the present invention; and FIGURE 21 is a vertical section of an electric generator adapted to- the turbocharger of FIGURES 1-8 and for adaption to the turbojets and turbofan of FIGURES 16-20. FIGURE 1 is a perspective view of a turbocharger 20 embodying the present invention. The turbocharger includes an outer structure 22 consisting of a compressor housing unit 24 coupled to a turbine housing unit 26 by a V-clamp band 28. Referring to FIGURES 1 and 2, compressor housing unit 24 includes a tubular inlet port 40 with a transverse wall 42 attached to one end of port 40 and extending outwardly therefrom. A circumferential chamber 44 is attached from wall 42. Inlet port 40 defines a compressor air inlet 50 and circumferential chamber 44 defines a compressor exhaust 52. Turbine housing 26 defines a turbine air inlet 54 and a turbine exhaust 56. In operation of the turbocharger, air is drawn into inlet 50 and compressed air is discharged from exhaust 52 to an internal combustion engine to which the turbocharger is mounted. Exhaust air from the engine is channeled into turbine air inlet 54 to drive the turbocharger turbine and is exhausted through turbine exhaust 56. Referring still to FIGURES 1 and 2, a bearing support cylinder 60 is mounted within inlet port 40 by a plurality of vanes 62 extending from the inside wall surface 64 of inlet port 40. A cap 66 is mounted over the end of support cylinder 60. A piston type actuator 80 is mounted by bracket 82 (FIGURE 1) to turbine housing 26. Actuator 80 includes a controller 84 operated to extend and retract control rod 86 as will be discussed hereinafter in greater detail. Air lines 88 and 89 provide air to controller 84 as necessary to operate rod 86. An oil reservoir cover plate 90 is attached to compressor housing unit 24 by a plurality of screws 92. Referring specifically to FIGURE 2, a compressor backwall 100 and a turbine backwall 102 are positioned intermediate of compressor housing unit 24 and turbine housing unit 26 when these two units are assembled. These four components are piloted one to another and held in assembly by V-clamp 28. As can be appreciated from a close review of FIGURE 2, only a single V-clamp is required to hold the entire assembly together. As previously described, compressor housing unit 24 includes a tubular inlet port 40 with a transverse wall 42 attached to one end thereof to one of the inlet ports and extending outwardly therefrom. A circumferential chamber 44 is attached to the end of wall 42 remote from inlet port 40 and has a varying area around its circumference increasing to the discharge provided by compressor exhaust 52 (FIGURE 1). Inlet port 40 has a first inside wall portion 110 having a converging diameter toward wall 42 and a second inside wall portion 112 joined to first inside wall portion 110 by a step 114. The second inside wall portion 112 has a diverging diameter toward wall 42. Wall 42 has a plurality of circumferentially spaced apertures 116 therethrough. Chamber 44 has an opening 118 substantially in the plane of wall 42 in addition to compressor exhaust 52. A forward compressor wall insert 126 includes a tubular throat 128 and a circular disc 130 attached transversely from one end of throat 128. Throat 128 has an inside wall surface 131 having a diameter converging toward disc 130 and an outer surface 132 having a diameter diverging toward disc 130. The diverging diameter surface 132 corresponds to the diverging surface of inside wall portion 112 of inlet port 40 such that throat 128 may be inserted within and mated with inlet port 40. The converging diameter inside wall surface 131 of throat 128 corresponds to the extension of converging diameter of first inside wall portion 110 of inlet port 40. When insert 126 is mated into inlet port 40, a continuous converging diameter is provided from the inlet of port 40 inwardly into the turbocharger. A plurality of rivet-like protrusions 140 extend from disc 130 and correspond to apertures 116 in wall 42. With the insert engaged to compressor housing 24 with the end of throat 128 engaging step 114 of inlet port 40, protrusions 140 are engaged through apertures 116 with disc 130 abutting the corresponding surface of wall 42. As is shown in FIGURE 2, protrusions 140 have been inserted into apertures 116 and the heads thereof deformed to attach insert 126 to housing 24. Disc 130 extends beyond wall 42 to partially cover opening 118 of chamber 44. A circumferential gap 146 is formed between the outer tip of disc 130 and the wall of chamber 44, and a diffuser area 148 is formed between disc 130 and compressor backwall 100 between centrifugal flow compressor rotor 172 and gap 146 leading to chamber 44. Referring still to FIGURE 2, bearing support cylinder 60 is supported concentrically within inlet port 40 by a plurality of vanes 62 extending inwardly from wall surface 64 of port 40. Turbocharyer 20 further includes a shaft 160 supported for rotation in bearing support cylinder 60 by two ball bearing assemblies 162 and 164. A radial flow turbine rotor 170 is mounted at one end of shaft 160 and a centrifugal flow compressor rotor 172 is mounted intermediate of turbine rotor 170 and bearing assemblies 162 and 164. Shaft 160 passes through aperture 176 in compressor backwall 100 and labyrinth seal 174 in turbine backwall 102. Turbine rotor 170 is fixedly attached to shaft 160, such as by welding, and compressor rotor 172 is retained in position on shaft 160 by retainer nut 180. Compressor rotor 172 is drilled to receive shaft 160 and counterbored to form a bore 182. Bore 182 has a diameter larger than the outer diameter of retainer nut 180 such that retainer nut 180 may be pressed onto shaft 160 into engagement with the botom wall 184 of bore 182 to retain the compressor rotor in position on shaft 160. A compressor rotor shim 186 is positioned between compressor rotor 172 and a step 188 in shaft 160 to accurately position the compressor rotor in the axial direction. A ring 200 is fitted within the end of cylinder 60 adjacent compressor rotor 172 and is prevented from moving into cylinder 60 by a retaining ring 202 attached to cylinder 60. Outer raceway 204 of bearing assembly 164 is formed in ring 200, the inner raceway 206 being integrally formed in shaft 160. Balls 208 are engaged between the inner and outer raceways to form bearing assembly 164. Bearing assembly 162 includes inner raceway 210 formed integrally in shaft 160 and an outer ring 212 slidable within cylinder 60 with an outer raceway 214 formed therein for receiving balls 216. A compression spring 218 is engaged between ring 212 and a retaining ring 220 fixed within cylinder 60 and biases ring 212 outwardly to fix the position of balls 216 and 208 in bearing assemblies 162 and 164, respectively, thereby fixing the position of shaft 160. The outer raceway 204 is formed in ring 200 with the ball radius on only one side. Thus, the assembly of bearing assembly 164 is made by positioning a full complement of balls 208 in raceway 206, and engaging ring 200 therearound. Similarly, outer raceway 214 is formed in ring 212 with the ball radius on only one side. Balls 216 of bearing assembly 162 are assembled by moving outer ring 212 to compress spring 218 and inserting a full complement of balls 216 in raceway 214 of shaft 160. By releasing ring 212, spring 218 automatically forces the ring into engagement with balls 216 to form bearing assembly 162 while simultaneously engaging riny 200 against balls 208 of bearing assembly 164. Alternatively, less than a full complement of balls 208 and 216 may be used in bearing assemblies 162 and 164 by the use of an appropriate retainer. Depending upon the application, an oil impregnated retainer or a sacrificial retainer which replenishes a self-lubricating coating to the balls may be used. The mounting of shaft 160 within cylinder 60 is completed by the engagement of cap 66 on the end of cylinder 60 to close the opening in cylinder 60 remote from compressor rotor 172. The use in the present bearing system of the ball bearing arrangement employiny integral inner raceways permits a larger diameter shaft and thus provides a very "stiff" shaft. Additionally, this bearing arrangement provides a very tight bearing system permitting very little radial or axial movement. As a result, the present bearing system substantially reduces the clearance required between the compressor and turbine and surrounding housing, and concentricity problems are minimized. In a preferred embodiment of the invention, bearing assemblies 162 and 164 are "starved" of oil. The only lubrication provided to the bearing assemblies is through wicks 222 and 224 which transfer oil from a reservoir R by capillary action to ramps or slingers 226. Oil supplied to slingers 226 is projected by centrifugal force to bearing assemblies 162 and 164 during rotation of shaft 160. In this way, the use of engine oil as a lubricant for the turbocharger bearings, and the associated plumbing and seals are eliminated. Moreover, the failures resulting from the use of contaminated engine oil as a lubricant or the lack of engine oil during starts is avoided. Moreover, no oil seals are required and bearing failure resulting from the failure of seals is also eliminated. Alternatively, the bearing assemblies may be permanently lubricated with a heavy consistency oil or grease which is packed into the raceways and around the balls of the bearing assemblies. As another alternative, an oil impregnated phenolic retainer may be used to provide lubricant to the balls for a considerable period. In either of these cases, the need for wicks 222 and 224 and slingers 226 would be eliminated although with a reduced bearing life. In conventional turbochargers where journal bearings and disc type thrust bearings are employed, continuous lubrication of the bearings is requried. Additionally, because the turbine is subjected to temperatures up to 16000 F, where the bearings are adjacent the turbocharger turbine, continuous lubrication is required to sufficiently cool the bearings to prevent failure through overheating. Even ball bearings would require a continuous flow of oil for cooliny. The ability of the present system to successfully function without conventional flood lubrication used to both lubricate and cool the bearings is the result of the particular arrangement of the type of bearings used in the present invention and the relative location of the bearings to the compressor and turbine. As will be described hereinafter in yreater detail, because the present invention eliminates the need for a continuous flow of oil for bearing lubrication and cooling, the present turbocharger may be mounted at any desired orientation. In contrast, conventional turbochargers have been severely limited as to their possible orientation. In the present invention, the journal and disc bearings of conventional turbochargers are replaced by the more precise ball type bearing assemblies, thereby eliminating the need for a continuous flow of lubrication for the bearings. Additionally, both the compressor and the turbine of the present turbocharger are overhung to one side of the bearing assemblies, and the turbine is maximally removed from the bearing assemblies with the compressor positioned between the bearing assemblies and the turbine. As this arrangement provides sufficient thermal insulation between the turbine and the bearing assemblies, the bearings will not be sufficiently heated as to require conventional lubrication methods. The back to back compressor/turbine arrangement of the present invention not only reduces substanstantially the heat conducted to the bearing assemblies but also minimizes the thermal expansion effects, thereby lowering the blade tip clearances required. This arrangement further eliminates the conventional bearing housing and provides a more compact package than present straddle mounted rotors having the support bearings intermediate of the compressor and turbine. Additionally, the use of antifriction ball bearing assemblies 162 and 164 provides much better control over the radial and axial movement of the compressor and turbine, thereby allowing reduced blade tip clearance. This in turn appreciably improves the compressor and turbine efficiency. Compred to journal bearings, the use of the anti friction ball bearing assemblies 162 and 164 also reduces the turbine work required to drive the bearings. This in turn reduces the engine back pressure resulting in the improvement of the specific fuel consumption as well as enhancing the ability to accelerate the rotor. The present turbocharger also provides for a nozzle area control structure 228 for selectively varying the turbine nozzle area to control the speed or pressure output of the turbocharger. Referring to FIGURES 1 and 2, exhaust gas from the internal combustion engine on which the turbocharger is mounted is injected into the turbocharger through turbine air inlet 54 and channeled against the blades of turbine rotor 170 through a nozzle area 230 formed by turbine backwall 102, a wall 232 parallel thereto and the nozzle vanes 234. This nozzle area is controlled by structure 228 including a plurality of movable nozzle vanes 234 positioned circumferentially about the nozzle area and rotatable to vary flow velocity and angle of exhaust gas to turbine rotor 170. The vanes 234 include trunnions 236 and 238 extending from opposite sides thereof. Trunnion 236 extends through turbine bacwall 102 and is attached to actuation lever 240. Trunnion 238 extends into wall 232. A nipple 242 is formed on one end of each actuation lever. These nipples extend into radial slots 244 formed in a control ring 246. Control ring 246 and actuation levers 240 are situated in air space yap 247 intermediate of compressor rotor 172 and turbine rotor 170. Control ring 246 is concentrically positioned about the axis of shaft 160 and is received on a cylindrical surface 248 extending from compressor backwall 100. The control riny 246 includes an inner ring 250 and an outer ring 252 formed with an inner and outer raceway, respectively, for receiving a plurality of balls 254 therebetween. Inner ring 250 is fixedly attached to the cylindrical surface 248 extending from compressor backwall 100, and outer riny 252 rotates angularly relative to the inner ring. By the rotation of outer ring 252, each of the actuation levers 240 is rotated about the axes of trunnions 236 and 238, resulting in the simultaneous rotation of each nozzle vane 234. One of the actuation levers 240 is provided with an extension 262. Control rod 86 is attached to the end of extension 262 remote from nipple 242. By the movement of control rod 86, actuation lever 240 is pivoted to angularly rotate outer riny 252 of control riny 246 thereby rotating each of the other actuation levers 240 and nozzle vanes 234 attached thereto. Controller 84 is designed to extend control rod 86 to open nozzle vanes 234 to turbine rotor 170 at low and high manifold pressures and to retract control rod 86 to close these nozzle vanes at intermediate pressures. More specifically, while operating at a closed throttle position where the intake manifold is under a vacuum condition, for example with manifold pressures of 5 to 8 pounds per square inch absolute, the controller operates to extend rod 86 to open nozzle vanes 234 permitting the engine to operate with as little back pressure as possible. FIGURE 3 illustrates compressor housing unit 24 and forward compressor wall insert 126 and their respective molds used in die-casting these two pieces. Heretofore, the compressor housing portion of many turbochargers have been sand-cast so that the circumferential chamber in which compressed air is directed for channeling to the intake manifold of the engine with which the turbocharger is used, could be formed with a substantially enclosed configuration having a narrow circumferential gap for receiving compressed air therein, thereby allowing the formation of a diffuser. Forming the compressor housing unit in one piece by sand-casting is substantially more expensive and produces a less accurate structure with much rougher wall surfaces in the circumferential chamber than a comparable diecast unit. However, where the turbocharger compressor housing has been die-cast in the past, it has not been possible to produce the forward diffuser wall as is possible in a sand-casting because of the necessity of providing proper ingress and egress for the die-cast molds. The present invention provides a two component die-cast compressor housing unit which upon assembly provides the advantayes heretofore only afforded by a sand-cast unit. As is shown in FIGURE 3, compressor housing unit 24 is formed by using an outer mold 290, an inner mold 292, a core mold 294 and a cap mold 296. Referring still to FIGURE 3, mold 292 is formed with raised contour 298 to form circumferential chamber 44. Mold 292 also has a protrusion 300 for mating with a corresponding protrusion from mold 290 for forming inlet port 40, vanes 62 and bearing support cylinder 60. Core mold 294 and cap mold 296 are used to form compressor exhaust 52. As can be seen in FIGURE 3, molds 290, 292, 294 and 296 cooperate to make possible the die-casting of compressor housing unit 24. Molds 290 and 292 are constructed with abutting surfaces to form parting line 310 on housing unit 24. Molds 320 and 322 cooperate to produce forward compressor wall insert 126. Molds 320 and 322 have abutting surfaces which engage one another to produce insert 126 with a parting line 324 on the outer edge of disc 130. As can best be seen in FIGURE 3, throat 128 is formed with notches 326 which receive vanes 62 when insert 126 is mounted into housing unit 24. FIGURE 4, and section views 5, 6 and 7, illustrate the positioning and configuration of vanes 62. Referring to FIGURES 5, 6 and 7, each of the vanes 62 has a leadig edge 330 and a trailing edge 332 with a thicker intermediate midsection 334. In each case, the thickest midsection is that indicated by a line 336 defining the parting line between molds 290 and 292 used in the formatio of housing unit 24. Thus, vanes 62 may be formed by die-castiny using molds 290 and 292 to produce the desired airfoil configuration of a leading and trailing edge separated by a thicker midsection therebetween. This configuration, shown in FIGURES 5, 6 and 7, greatly facilitates the ingress of air into the compressor inlet area, and in the configuration of the present invention, may be cast using well known die-casting techniques. To accomplish an airfoil configuration for struts 62 such that the vanes taper from a thicker midsection to thinner leading and trailing edges, the die-cast molds must be inserted into inlet port 40 from both the forward and rearward ends. Thus, referring to FIGURE 3, the second inside wall portion 112 (FIGURE 2) is formed by protrusion 300 of mold 292 while first inside wall portion 110 (FIGURE 2) is formed by mold 290. Both the first and second inside wall portions 110 and 112, respectively, diverge outwardly to permit removal of the die-cast mold after formation of the piece. Thus, the formation of the desired geometry of struts 62 requires a diverging diameter wall portion 112 in inlet port 40 to permit a removal of the diecast molds. However, it is critical to have a continuously converging diameter from the inlet of inlet port 40 to the compressor rotor 172. This is accomplished by use of wall insert 126. Wall insert 126 is formed, also by die-casting, with a diverging surface of inside wall portion 112 of inlet port 40 for mating therewith. Inside wall surface 131 of throat 128 is formed with a diameter converging toward disc 130 corresponding to the extension of the converging diameter of first inside wall portion 110 of inlet port 40. Thus, when insert 126 is mated with inlet port 40, a continuous converging diameter is provided from the inlet of port 40 inwardly to compressor rotor 172 (FIGURE 2). Thus, the present invention provides a two-piece structure for forming the compressor housing for a turbocharger, both of which may be die-cast. Upon assembly, these two components produce a compressor housing having a plurality of struts 62 supporting a bearing support cylinder 60 with the vanes having a thicker intermediate section converging to a thinner leading edge and to a thinner trailing edge. The housing further provides a continuously converging inlet nozzle from the inlet of the inlet port to the compressor rotor. Further, the compressor housing provides a forward diffuser wall for completing the circumferential chamber in which compressed gases are channeled to the compressor exhaust. FIGURE 8 shows an adaptation of the invention illustrated in FIGURE 2 wherein differiny geometries of wall inserts 126 may be substituted one for the other for use with corresponding compressor rotors. Referring to FIGURE 16, wall insert 126a provides a more restrictive air flow into the turbocharger while wall insert 126b provides for a larger compressor rotor and greater air flow into the turbocharger. It will be now appreciated tht modification of the design of the present invention may be accomplished by merely fitting differing wall inserts 126 to a standard compressor housing unit 24. Thus, several different turbochargers, having different flow capabilities, may be produced from the present invention using a standard compressor housing unit 24 by selecting one of any number of possible geometries for wall insert 126 with corresponding compressor wheels. This feature is significant in that wall insert 126 is the simplier component of the compressor housing unit. In prior art turbocharger units, either of the die-cast or sand-cast variety, any modifications would involve producing a totally new casting for each new design. In the present invention, a different air flow/pressure ratio compressor design is achieved by simply substituting a wall insert of a different design in conjunction with a new or modified compressor wheel. Therefore, the present invention provides a turbocharger compressor housing unit which may be die-cast. The compressor rotor housing unit includes a compressor housing and forward wall insert for engagement with the housing. This two component construction permits each of the two components to be die-cast using standard die-castiny techniques. In their combined configuration, a compressor housing is produced having a circumferential chamber closed on all sides except for a circumferential gap for receiving compressed gases from the compressor rotor. A circumferential passageway is also provided leading to this gap to the chamber wherein accelerated gases are diffused to increase static pressure. Moreover, a compressor bearing support cylinder is cast concentric with the inlet port and supported therein by a plurality of vanes extending from the inner wall of the inlet port. The vanes are formed with a leading and trailing edge separated by a thicker midsection. This is accomplished through the use of molds having a parting line substantially at the thicker cross sectional area to permit diecasting of the compressor housing. While the present invention of die-casting a compressor housing unit in two components has been applied to a turbocharger wherein the compressor rotor and turbine rotor are overhung to one side of and supported from a shaft rotatable on ball bearing assemblies, it will be apparent to oe skilled in the art that the present invention may readily be adapted to turbochargers of the conventional design having the compressor rotor and turbine rotor supported on opposite sides of shaft bearing support assemblies. In this particular application, the heretofore described compressor housing unit would be directly usable with only modification of the bearing support cylinder. A critical feature of the present turbocharger is its capability of performing over an extremely wide range of compressor speeds and flows without experiencing a "surge line" commonly encountered in conventional turbochargers. This highly significant feature is demonstrated by reference to the performance graphs, known as "compressor maps", illustrated in FIGURES 9 and 10. FIGURE 9 illustrates a typical compressor map for a conventional turbocharger, while FIGURE 10 illustrates a compressor map for the turbocharyer of the present invention. These maps plot air flow in cubic feet per minute versus the ratio of discharge pressure to inlet pressure for the turbocharger compressor. Referring to FIGURE 9, constant compressor speed lines 430 and isentropic efficiency lines 432 are shown. A surge line 434 identifies the performance points to the left of which the turbocharger compressor cannot operate to produce a uniform output of air. While the components of the turbocharger may be modified such that the surge line is shifted toward the vertical axis to provide for stable operation at lower turbocharger speeds, and thus lower engine speeds, such a shifting of the operating characteristics of the turbocharger reduces the high speed capabilities of the unit. Therefore, turbochargers have heretofore been relegated to providing increased performance at only higher engine speeds. .The present invention provides a turbocharger capable of producing a uniform output at very low turbocharger air flows and effectively eliminates the surge line limitation encountered in conventional turbochargers. Referring to FIGURE 18, compressor performance map for the turbocharyer of the present invention is illustrated including constant compressor speed lines 440 and efficiency lines 442. As can be appreciated by viewing the compressor map illustrated in FIGURE 10, the compressof the present turbocharger continues to operate with no irregularity in compressor output to very low air flow values. Effectively, the turbocharger of the present invention does not experience a "surge line" corresponding to that illustrated in the compressor map of FIGURE 9. Referring to FIGURES 9 and 10, the breadth of the operating range of the conventional turbocharger may be compared with that of the present invention. Referring specifically to FIGURE 9, at a compressor pressure ratio of 1.9, the air flow range varies from a high of 350 at an efficiency of 60% to a low of 200 cubic feet per minute at the surge line. Therefore, this ratio of high to low flow rate (350 divided by 200) is 1.75. Referring to FIGURE 10, at a pressure ratio of 1.9, the present turbocharger operates from a flow rate of 275 at a 60% efficiency to a low of 60 cubic feet per minute without encountering a surge line. The ratio of the high to ow flow rate (275 divided by 60) is 4.58, an increase of over two and one-half that of the conventional turbocharger. This achievement is highly significant in that the turbocharger can be effectively used to improve performance both at lower engine speeds as well as at higher engine speeds. This development becomes even more significant when coupled with the feature of the present invention for providing a constant compressor speed for varying engine speeds or constant boost at varying engine speeds in that a higher desired pressure ratio may be attained at low engine rpm's without surge or turbulence problems normally experienced at the lower compressor flows in conventional turbochargers. This significant advancement provided by the turbocharger of the present invention is primarily attributable to the compressor air inlet configuration in conjunction with advanced radial flow compressor technology - such as backward swept blading. As has been described, bearing support cylinder 60 is supported within tubular inlet port 40 by a plurality of struts 62 extending from the inside wall of inlet port 40 to the bearing support cylinder 60. In one embodiment, three struts extend from the inside wall of the inlet port to the bearing support cylinder to position the cylinder concentrically within the compressor air inlet. As a result, the inlet is divided into more than one inlet channel. Additionally, these channels are proportionately long in the flow direction compared to any width dimension. Further, the struts have a contour including a leading and trailing edge narrower than an intermediate section of the strut. As is also shown in FIGURE 2, the inside wall portion of inlet port 40 has a converging diameter from the inlet end to the area adjacent compressor rotor 172. This structure stabilizes the back flow conditions normally encountered at low compressor flows. By stabiliziny the back flow conditions, the compressor is able to continue to function to provide a steady state flow of air at much lower compressor flows than heretofore possible in conventional turbochargers. FIGURE Il illustrates a vertical section of an alternative embodiment of the turbocharger illustrated in FIGURES 1-8. The turbocharger of FIGURE 11 is identical to the turbocharger illustrated in FIGURES 1-8 with the exception that an axial stage compressor rotor 450 is mounted in the compressor inlet port. Because of the substantial identity between many components in the alternative embodiment illustrated in FIGURE 11 and the turbocharger illustrated in FIGURES 1-8, like or corresponding parts are identified by the same numeral. In the embodiment of FIGURE 11, the compressor inlet port is modified to include a larger diameter inlet port 452 having an inner wall 454 defining the inlet channels 456 to radial compressor rotor 172. A plurality of stators 458 extend from inner wall 454 of inlet port 452 to support bearing support 460. An axial stage compressor rotor 450 is mounted on the end of shaft 160 on the side of bearing assemblies 162 and 164 opposite compressor rotor 172 and is retained in position by an appropriate nut 462. The compressor rotor includes a hub 464 and a plurality of struts 466 attached between hub 464 and a plurality of struts 466 attached between hub 464 and struts 468. Hub 464 engayes a step 470 on shaft 160 and is positioned between step 470 and nut 462. As can be appreciated from viewing FIGURE 11, air entering inlet port 452 is compressed by the axial stage compressor and is carried through channels 456 to radial compressor rotor 172. The use of a two-stage compressor is significant in that a broader operating range may be accomplished with the use of a two-stage compressor as compared to the range possible from a single stage compressor. For example, in use of a two-stage compressor, the first stage may be used to achieve a pressure ratio of inlet pressure to discharge pressure of 1.5 to 1.6 while the second stage may be used to achieve a pressure ratio of 3.0 to 3.5. These combined pressure ratios effectively produce a pressure ratio on the order of 4.5 to 5.6. While such pressure ratios may be achieved in a single stage, the higher compressor speed required to produce such pressure ratios would dictate the use of higher quality and more expensive compressor and turbine components as well as producing significant flow range restraints. In the present arrangement, the twostage unit accomplishes the higher pressure ratios without this additional expense or disadvantage. Moreover, in the present invention, the axial stage compressor is mounted on the opposite side of the bearing support structure from the radial compressor and turbine rotors thereby providing balance to the system and no particular ill effects. FIGURES 12-15 illustrate a novel way of mounting the turbocharyer illustrated in FIGURES 1-8 on an internal combustion engine. FIGURES 12 and 13 illustrate a vertical section view and top plan view, respectively, of turbocharger 20 mounted on a V-6 engine 444. Of course, it will be understood that this same application can be made on a "V" engine of any number of cylinders. Engine 444 represents a conventional V-arrangement engine having a right cylinder bank 445 and a left cylinder bank 446. The section shown in FIGURE 12 illustrates a section through an exhaust valve 448 in the right cylinder bank 445 and through an intake valve 449 on the left cylinder bank 446. Turbocharger 20 is mounted with the turbine and compressor rotational axis in a vertical position, an orientation not heretofore possible for conventional turbochargers. Because of the provisions in the present turbocharger for providing oil to the bearing assemblies by way of wicks and the corresponding construction which eliminates the need for a continuous flow of lubricant to the bearings, the present invention may be oriented with the compressor and turbine rotational axis in a true vertical orientation or any angle between vertical and horizontal. By contrast, conventional turbochargers, normally requiring a flow of lubrican to and from the bearing structures, have not been successful in operating in a true vertical orientation as illustrated in the arrangement of FIGURES 20 and 21. Referring still to FIGURES 12 and 13, engine exhaust is channeled to turbocharger 20 by way of manifold 451 wherein exhaust gases are communicated directly to turbine rotor 170 of turbocharger 20 from each individual exhaust valve. Turbocharger compressor exhaust is fed into the cylinders of engine 444 through manifolds 447 by way of cross over tubes 453 to intake valves 449. In operation, air is drawn into turbocharger 20 at inlet 50, is compressed by compressor rotor 172, and discharged through tubes 453 to manifolds 447 into the cylinders on both the left and right banks of the engine. Exhaust gas from the engine is delivered by way of manifold 451 to turbine rotor 170 at spaced points therearound and thereafter discharged through exhaust duct 455. This spacing allows the turbine to utilize the high energy pulses created when the exhaust valve first opens. As can be appreciated from viewing FIGURES 12 and 13, the turbine rotor is mounted in a turbine housing having a circumferential chamber with the variable nozzles therein aligned substantially in a plane perpendicular to the axis of rotation of the turbine rotor. Further, the engine exhaust ports are aligned in a common plane oriented horizontally. As can be seen the normal turbine housing commonly used is replaced by manifold 451 which serves as both exhaust manifold and turbine housing. The ability to use the present invention in a vertical orientation makes possible the alignment of the plane of the exhaust ports substantially parallel to the plane of the circumferential chamber of the turbine housing by positioning the turbine shaft axis substantially perpendicular to the plane of the exhaust ports. In this way, the exhaust gases from the exhaust ports may be more directly and effectively injected to the turbine housing for driviny the turbine rotor In contrast, prior turbocharyer units have required the use of manifolds having extremely complicated designs for directing exhaust gases from the exhaust ports to the turbine rotor. Further, in the present invention, the exhaust manifold directs exhaust gases from each of the exhaust ports from the engine to points substantially equally spaced around the turbine rotor, thus communicating exhaust gases to different points about the circumference of the turbine rotor. In this way, the cyclic exhaust pulses from the engine exhaust ports are distributed about the circumference of the turbine rotor to take advantage of these pulses. The vertical orientation of the present turbocharger also makes possible the nesting of the turbocharger between the banks of the cylinders in close proximity to the engine. Further, the exhaust gases may be ported by way of exhaust manifold directly from the cylinders to the turbocharger turbine with very little loss of energy prior to application of the exhaust gases to drive the turbine. It will be understood that a carburetor may be mounted directly above the turbocharger to feed a fuel air mixture into inlet 50. Likewise, the turbocharger may be used on a fuel injection or diesel engine where fuel is fed directly into the engine cylinders. Referring now to FIGURES 14 and 15, the turbocharger of the present invention mounted in a vertical position is shown in use on an in-line four cylinder engine. Of course, it will be understood that the invention also envisions the use of the present turbocharger on an in-line engine of more or less than four cylinders. In the embodiment illustrated in FIGURES 22 and 23, turbocharger 20 is connected to engine 480 by way of an exhaust manifold 482 communicatiny between the exhaust valves of the engine cylinders to the turbocharger turbine. Air is drawn into the turbocharger at inlet 50, compressed by turbocharger compressor rotor 172 and discharged through manifold 484 into the intake valves of the engine cylinders. As can be seen in FIGURE 15, exhaust manifold 482 is formed such that the gases driving the turbocharger turbine are communicated to the turbine at spaced points about the turbine circumference. Further, the manifold is oriented to facilitate rotation of the turbine in a clockwise direction as viewed from FIGURE 15. Similarly, as can be seen from FIGURE 13, a similar manifold arrangement is provided when the turbocharger is mounted intermediate of two banks of cylinders in a V-arrangement engine. Therefore, the present invention provides a turbocharyer which can be oriented with the axis of rotation of the turbine and compressor vertical or at any position intermediate of horizontal and vertical. This is made possible largely because of the provisions in the present invention for lubricating the bearing structures on which the compressor and turbine shaft rotate. Because the present invention may be so oriented, it is ideally suited for mounting to and use with conventional engines of all types and arranyements. The present turbocharger configuration described with respect to FIGURES 1-8 may be readily converted into an effective turbojet or turbofan engine as illustrated in FIGURES 16-20. While these embodiments are illustrated by a vertical section of only the upper half of apparatus, it will be understood that the lower half of the unit is substantially identical to the upper half shown. A turbojet 500 embodying the present invention is illustrated in FIGURE 16. Turbojet 500 includes an outer housing 502 consisting of a tubular inlet nozzle 504, main housing 506 and combustion chamber backwall plate 508. Backwall plate 508 includes an integral stiffener 510 and is attached to main housing 506 by bolts 512. A turbine exhaust nozzle 514 is supported within main housing 506 by attachment to the end of backwall plate 508 opposite main housing 506 by bolts 515. A bearing support cylinder 516 is mounted within tubular inlet nozzle 504 by a plurality of struts 518 extending from the inside wall surface 520 of inlet nozzle 504. This arrangement is similar to that illustrated in FIGURES 1-8 with respect to the bearing support cylinder 60 and its attachment within inlet port 40 of turbocharger 20. A cap 522 is mounted over the end of bearing support cylinder 516. Referring still to FIGURE 16, a compressor backwall 524 and turbine back wall 526 are positioned within main housing 506 and are attached one to the other by suitable screws 527. In the embodiment illustrated in FIGURE 16, a fixed stator vane 528 is mounted between main housing 506 and compressor backwall 524 by suitable screws 529. A combustion liner 530 is mounted between turbine backwall 526 and a transversely extending portion of turbine exhaust nozzle 514. Combustion liner 530 may be of a conventional design including a circumferential chamber having a plurality of ports formed therein. The liner includes ports 532 for primary air combustion and ports 534 for dilution air according to known practice. Fuel is supplied to the combustion chamber by fuel spray nozzles 536 extending through combustion chamber backwall plate 508 and upstream wall 538 of the combustion liner. An ignitor 540 is received within combustion liner 530 through upstream wall 538 and combustion chamber backwall plate 508. Combustion liner 530 has a mouth 542 leading to a turbine inlet area 544 formed between turbine backwall 526 and the transversely extending portion of turbine exhaust nozzle 514. A turbine inlet area control structure 546 is used in turbojet 500 illustrated in FIGURE 16 and is identical to turbine inlet area control structure 228 illustrated and described with respect to the turbocharger of FIGURES 1-8. More specifically, turbine inlet area control structure 546 includes movable nozzle vanes 548 positioned circumferentially about the nozzle area and rotatable to vary velocity and angle of flow of combustion gas through nozzle inlet 544. Vanes 548 include trunnions 550 and 552 extending from opposite sides thereof. Trunnion 550 extends through the transversely extending portion of turbine exhaust nozzle 514, and trunnion 552 extends through turbine backwall 526 and is attached to an actuation lever 554. The end of actuation lever 554 is engaged with the outer race of a ball bearing assembly 556, with the inner race of the ball bearing assembly being secured to compressor backwall 524 as discussed with respect to turbocharger 20 illustrated in FIGURES 1-8. Likewise, the operation of actuation lever 554 is identical to that discussed with respect to turbocharger 20 of FIGURES 1-8 to control the angular orientation of nozzle vanes 548 as desired. Bearing support cylinder 516 is supported concentrically within inlet nozzle 504, as previously described, by struts 518. A compressor rotor 570 and a turbine rotor 572 are supported on a shaft 574 mounted for rotation in bearing support cylinder 516 by two ball bearing assemblies 576 and 578. Turbine rotor 572 is mounted at one end of shaft 574 and radial flow compressor rotor 570 is mounted intermediate of turbine rotor 572 and bearing assemblies 576 and 578. Shaft 574 passes through turbine backwall 526 and through compressor backwall 524 wherein a labyrinth seal 580 formed around shaft 574 provides a seal between the compressor and turbine rotors. Turbine rotors 572 is fixedly attached to shaft 574, such as by welding, and compressor rotor 570 is retained in position on shaft 574 by a retainer nut 582. Nut 582 is of the same arrangement as nut 180 described with respect to the embodiments illustrated in FIGURES 1-8. Compressor rotor 570 is positioned between nut 582 and a step 586 in shaft 574. Referring still to FIGURE 16, a bearing ring 590 is fitted within the end of cylinder 516 adjacent compressor rotor 570 and is prevented from moving within cylinder 516 by a retaining ring 592 attached to cylinder 516. Outer raceway 594 of bearing assembly 578 is formed in ring 590, the inner raceway 596 being formed integrally in shaft 574. Balls 598 are received between inner and outer raceways to form bearing assembly 578. A bearing support cylinder 516 is mounted within inlet nozzle 504 by a plurality of struts 518 extending from the inside wall surface 520 of inlet nozzle 504. This arrangement is similar to that illustrated in FIGURES 1-8 with respect to bearing support cylinder 60 and its attachment within inlet port 40 of turbocharger 20. A cap 522 is mounted over the end of bearing support cylinder 516. Referring still to FIGURE 16, a compressor backwall 524 and turbine backwall 526 are positioned within compressor-burner housing 506 and are attached one to the other by screws 527. Bearing assembly 576 includes inner raceway 600 formed integrally in shaft 574 and an outer ring 602 slidable within cylinder 516 with an outer raceway 604 formed therein for receiving balls 606. A compression spring 610 is engaged between ring 602 and a retaining riny 612 fixed within cylinder 516 and biases ring 602 outwardly to fix the position of balls 606 and 598 in bearing assemblies 576 and 578, respectively, thereby fixing the position of shaft 574. The structure of the bearing assemblies for the turbojet 500 is identical to that arrangement used for turbocharger 20 illustrated in FIGURES 1-8. Therefore, the assembly and operation of the bearing assemblies is identical to that described earlier with respect to turbocharger 20. Likewise, the means of lubricating the bearing assemblies, wicks in contact with inclined ramps 614, is identical to that illustrated with respect to turbocharger 20 illustrated and described in FIGURES 1-8. In operation of the turbojet illustrated in FIGURE 16, air enters tubular air inlet port at its inlet 620 following the air path indicated by arrow 622. This air is compressed by compressor rotor 570 and is discharged radially therefrom along the air path indicated by arrow 624. This compressed air is delivered into a combustion chamber area 626 and into combustion liner 530 through ports 532 and 534. Air is mixed with fuel, injected into combustion liner 530 through nozzles 536. A stochiometric mixture is obtained and the mixture is ignited within combustion liner 530 through nozzles 536. A stochiometric mixture is obtained and the mixture is ignited within combustion liner 530 by ignitors 540. Cooling air is delivered into combustion liner 530 through ports 534 to cool the exhaust gases from combustion prior to their entry into turbine inlet area 544. These gases engage turbine rotor 572 to drive the rotor and the compressor rotor attached thereto by way of shaft 574. The combustion gases are thereafter discharged through nozzle 514 to the outer atmosphere, producing the thrust provided by the turbojet. As can be appreciated by review of the turbojet illustrated in FIGURES 16, the system is compact in size and has a minimum of components. Further, the bearing assemblies on which the turbine and compressor rotor shaft rotate are positioned away from turbine rotor 572 and the extremely hot combustion gases delivered thereto from combustion liner 530. Moreover, the serious problems encountered as a result of the extremely high temperatures such bearing structures are normally subjected to are completely eliminated by the unique bearing arrangement disclosed in the present invention. Because the bearings are removed from the extremely high temperatures associated with the combustion gases used to drive the turbine and indeed even insulated from these high temperatures by the compressor rotor and compressor backwall and turbine backwall, limited lubrication is sufficient for the successful operation of the unit. This eliminates the need for a constant flow of lubrication to the bearings as well as the numerous components necessary to provide such lubrication that would have to be driven by the rotating shaft. FIGURE 17 illustrates a turbofan 650. The structure of turbofan 650 is substantially identical to the structure of turbojet 500 illustrated in FIGURE 17 with the exception that a bypass air channel is provided in addition to the primary air channel and an axial staye compressor is provided upstream of the radial compressor. Referring to FIGURE 17, turbofan 650 includes an inlet nozzle 652, a main housing 654 and a combustion chamber backwall 656. Combustion chamber backwall 656 is attached to main housing 654 by appropriate bolts 658. A turbine exhaust nozzle 660 is attached by bolts 662 to combustion backwall 656. A compressor backwall 664 and a turbine backwall 666 are positioned within main housing 654, and a combustion liner 668 is mounted within a combustion chamber 670 with a mouth 672 opening between turbine backwall 666 and a laterally extending portion 674 of turbine exhaust nozzle 660. Combustion liner 668 is formed with a plurality of ports 676. A fuel injection unit 678 is received through combustion backwall 656 into liner 668. An ignitor 680 is also received within liner 668 for igniting fuel air mixtures in operation of the turbofan. A stator vane 682 is mounted between main housing 654 and compressor backwall 664 by suitable screws. A bearing support cylinder 684 is mounted within inlet nozzle 652 by a plurality of struts 686. A plurality of stator vanes 688 are also mounted in the inlet nozzle 652 for cooperation with the axial stage compressor as will be discussed hereinafter in greater detail. Shaft 690 is supported within bearing support cylinder 684 by bearing assemblies 692 and 694. Bearing assemblies 692 and 694 are identical to those described with respect to turbojet of FIGURE 16 and the turbocharger illustrated in FIGURES 1-8, and reference is hereby made to the earlier description thereof. An oil chamber 696 is formed between inner wall 698 of inlet nozzle 652 and bearing support cylinder 684. An appropriate ring 700 with O-rings 702 and 704 are positioned in the mouth of chamber 696 and retained in position by ring 706. Wicks 708 and 710 communicate through oil chamber 696 to provide oil to inclined ramps 712 and 714, respectively, thereby providing lubrication to bearing assemblies 692 and 694 as described earlier with respect to the embodiments of FIGURES 1-8 and FIGURE 16. A radial compressor rotor 716 and turbine rotor 718 are mounted on shaft 690 and a turbine inlet control structure 720, identical to that discussed with respect to the embodiments of FIGURES 1-8 and FIGURE 16, is incorporated to control the velocity and angle of combustion gases to turbine rotor 718. A bypass flow channel 722 is formed between an inner bypass wall 724 and outer bypass wall 726. Outer bypass wall 726 is attached to inner bypass wall 724 by a plurality of stator vanes 728 positioned therebetween. Outer bypass wall 726 is positioned from main housing 654 by a plurality of struts 730 spaced circumferentially around housing 654. An axial stage compressor rotor 732 is attached to shaft 690 by an appropriate nut 734 engaging rotor 732 against a retaining ring 736. Rotor 732 includes a hub 738 and a plurality of vanes 740 extending radially therefrom. A plurality of cylindrical armatures 742 are embedded within hub 738 of rotor 732 and cooperate with a stationary field winding 744 mounted adjacent thereto from outer bypass wall 726 by struts 746 to produce electric current. The operation of the turbofan illustrated in FIGURE 17 is substantially similar to that of the turbojet illustrated in FIGURE 16 with the exception that air entering the inlet of the turbofan at axial staye compressor rotor 732 is divided into a bypass flow indicated by arrow 747 and a primary flow indicated by arrow 748. Bypass air is compressed and discharged through a bypass nozzle 749 producing thrust from the turbofan. Primary air is directed along the path indicated by arrow 748 and is compressed by axial stage compressor rotor 732 and radial compressor rotor 716 prior to being mixed with fuel in combustion liner 668 and ignited therein. The ignited gases move past the turbine inlet area control structure and against turbine rotor 718 to drive the turbine rotor, as well as the axial stage compressor rotor 732 and radial compressor rotor 716. Exhaust gases from turbine rotor 718 are discharged through turbine exhaust nozzle 660 producing additional thrust to the turbofan. The turbine inlet control structure 720 is identical to that illustrated and described with respect to turbocharger 20 illustrated in FIGURES 1-8 and turbojet 500 of FIGURE 16. This control structure operates to control both the velocity and angle of combustion gases directed against turbine rotor 718 from combustion liner 668. During rotation of axial stage compressor rotor 732, armatures 742 are rotated relative to windings 744, causing the generation of electricity therefrom. This electricity may be used to operate various engine or aircraft systems as desired and provides a very economical and compact energy package for the system. Referring now to FIGURES 18 and 19, an alternative embodiment of the turbojet illustrated in FIGURE 16 is shown and identified generally by the numeral 750. Turbojet 750 includes an inlet cylinder 752 joined to a main housing 754 with a back plate 756 attached to main housing 754 by a plurality of bolts 758. A turbine exhaust nozzle 760 is attached to the end of back plate 756 opposite main housing 754 by appropriate bolts 762. Turbine exhaust nozzle includes an exhaust cylinder 764 and a laterally extending portion 766 formed to join main housing 754. A bearing support cylinder 768 is supported from inlet cylinder 752 by a plurality of stators 770. A shaft 772 is supported within cylinder 768 by bearing assemblies 774 and 776. Bearing assemblies 774 and 776 are identical in structure and operation to bearing assemblies 576 and 578 illustrated with respect to the embodiment of FIGURE 16. A turbine rotor 778 is formed integrally with shaft 772 and a compressor rotor 780 is mounted on shaft 772 intermediate of turbine rotor 778 and bearing assemblies 774 and 776. A compressor backwall 782 and a turbine backwall 784 are mounted within main housing 754. A plurality of stator vanes 786 are mounted between main housing 754 and compressor backwall 782 by screws 788. A suitable ignitor 789 is mounted within lateral extending portion 766 of turbine nozzle 760 into the chamber formed between that wall and turbine backwall 784. A turbine nozzle inlet area control structure 790 including a movable vane 792 supported for rotation on trunnions 794 and 796 within transverse wall 766 and turbine backwall 784, respectively, is provided. This turbine nozzle inlet area control structure 790 is identical to that structure disclosed and illustrated in the embodiment of turbocharger 20 of FIGURES 1-8 and turbojet 500 of FIGURE 16. A labyrinth seal 800 is formed within turbine backwall 784 to provide an effective seal between the turbine and compressor areas. Compressor rotor 780 is mounted on shaft 772 by nut 802 engaging rotor 780 against a step 804 in shaft 772. An axial compressor 806 rotates with shaft 772 to cooperate with stators 770 to compress air directed into compressor inlet 808 formed by inlet cylinder 752. Compressed air is directed along a path indicated by arrow 810. In the embodiment illustrated in FIGURES 18 and 19, shaft 772 is formed with an axial bore 812 therein. A fuel supply conduit 814 is connected with bore 812 to provide a supply of fuel within the axial bore. An appropriate seal 816 is positioned between fuel supply conduit 814 and the surface of bore 812 to prevent loss of fuel at the point of connection of the conduit and the shaft. A plurality of radial ports 818 are formed through shaft 772 to communicate between bore 812 and an annular groove 820 formed in compressor rotor 780. A plurality of radial ports 822 communicate from groove 820 through compressor rotor 780. Suitable seal means such as O-rings 826 and 828 are mounted in annular yrooves within rotor 780 to prevent leakage of fuel at the point of connection between the rotor and shaft 772. In operation of the turbojet illustrated in FIGURES 18 and 19, fuel is supplied to bore 812 of shaft 772 through fuel supply conduit 814. A fuel supply path is provided between bore 812 and the air flow path indicated by arrows 810 (FIGURE 18) through ports 818, groove 820 and ports 822. This fuel flow path is indicated by arrows 838. As compressor rotor 780 is rotated, fuel is carried by centrifugal force from bore 812 through this fuel path into the air path indicated by arrows 810. Simultaneously therewith, air is drawn into inlet port 808 by axial stage compressor 806 and is delivered in a compressed state along the air path. This air is further compressed by radial compressor rotor 780 and mixed with the fuel downstream of the compressor rotor. The fuel is highly atomized as a result of the action of the compressor rotor blades on the fuel as it is ejected from the ports 822 through the compressor rotor. This atomized fuel when mixed with the compressed air delivered into the turbojet is directed along the air path and is ignited by ignitor 836 upstream of turbine rotor 778. The exhaust gases resulting from combustion move past the vanes of turbine rotor 778 to drive the rotor in a conventional manner. These exhaust gases are then discharged through nozzle 760 to provide thrust from the turbojet. It will be understood that the combustion temperature is considerably greater with this system of combustion and would require materials capable of withstanaing the greater temperatures. The system of FIGURES 17 and 18 eliminates many of the components heretofore required in conventional turbojets. The unique fuel supply system illustrated in FIGURES 17 and 18 eliminates the need for a fuel pump and all associated hardware. The conventional fuel pump is replaced by a fuel system which automatically discharges fuel in an atomized state by projecting the fuel through a bore in the compressor rotor shaft and through ports in the compressor rotor itself into the air stream compressed by the rotor. The system of FIGURES 17 and 18 further provides a two-stage compression arrangement, wherein an axial stage compressor is applied upstream of the radial or centrifugal compressor. This arrangement provides additional balance to the system by providing the axial stage compressor on the side of the bearing structures opposite that of the radial compressor. Further, this arrangement positions the bearing structure remote from the turbine rotor and combustion chamber immediately upstream of the turbine rotor. This arrangement insulates the bearing structure from the extreme temperatures experienced in this area of the system. Therefore, no oil system is required. Moreover, the units are adaptable to very small turbojets or turbofans. FIGURE 20 shows an alternative embodiment of the turbojet illustrated in FIGURE 19 to produce a turbofan 900. The structure of turbofan 900 is substantially identical to turbojet 750 illustrated in FIGURE 19 with the exception that a bypass air channel is provided in addition to the primary air channel. The turbofan includes an inlet cylinder 902 joined to a main body 904 and a backwall 906 attached to main housing 904 by bolts 908. A turbine exhaust nozzle 910 is supported from backwall 906 by bolts 912 with a laterally extending portion 913 of nozzle 910 in engagement with main housing 904. A bearing support cylinder 914 is supported from inlet cylinder 902 by a plurality of struts 916. A compressor backwall 918 and turbine backwall 920 are supported within main housing 904. A turbine inlet area control structure 921 identical to that disclosed with respect to structure 790 of the turbojet of FIGURE 18 is provided. A shaft 922 is supported for rotation within bearing support cylinder 914 by bearing assemblies 923 and 924. These bearing assemblies are identical to those disclosed with respect to the turbojet illustrated and described in FIGURE 18. A turbine rotor 926 is mounted to one end of shaft 922 and a compressor rotor 928 is mounted intermediate of turbine rotor 926 and bearing assemblies 923 and 924. In the embodiment illustrated in FIGURE 20, an axial compressor rotor 930 is mounted to the end of shaft 922 and directs air along a primary flow path within inlet cylinder 902 and a secondary flow path formed between outer secondary flow wall 932 and inner secondary flow wall 934. Outer secondary flow wall 932 is supported from inner wall 934 by a plurality of stators 936. Air directed through the secondary flow path, indicated by arrow 938, is compressed by the action of compressor rotor 928 and stators 936 and is exhausted through exhaust nozzle 940 to produce thrust from the turbojet. Air directed along the primary flow path, indicated by arrow 942, is compressed by rotor 928 and mixed with fuel supplied into the air stream in an identical way as described with respect to the embodiment of FIGURE 18 and ignited by an ignitor 946. The combustion gases are directed through turbine inlet area control structure 921 to drive turbine rotor 926 and compressor rotors 930 and 928. Air exhausted past turbine rotor 926 through turbine exhaust nozzle 910 provides further thrust from the turbofan. FIGURE 21 illustrates a further embodiment of the systems illustrated in the prior figures wherein an electrical generator 970 is mounted within the compressor inlet nozzle. Referring now to FIGURE 21, electrical generator 970 includes an armature 972 mounted on the end of compressor and turbine shaft 974. As is seen in FIGURE 19, shaft 974 is supported by bearing assembly 976 and a second bearing assembly (not shown) identical to the bearing assemblies shown with respect to the turbocharger of FIGURES 1-8 and the turbojets of FIGURES 16-20. A field winding 978 is mounted within bearing support housing 980, which is in turn concentrically mounted within compressor inlet nozzle 982 by vanes 984 in the same manner discussed earlier with respect to both the turbocharger and turbojet and turbofan embodiments. A cap 986 is mounted on the end of bearing support housing 980. In operation of the generator, the armature 972 rotates with shaft 974 within field winding 978 to produce an electrical current in the well known manner. Electric current so produced is directed by way of leads (not shown) from field winding 978 to any point in the system requiring electrical power. Thus, with respect to the present invention as used on a turbocharger, the generator may be used to supply electric current for any components in an automobile or othe equipment requiring electrical power. With respect to application of the invention disclosed in FIGURE 21 to the turbojets of FIGURES 16-20, electrical energy may be used for guidance systems or other components requiring electrical power. Thus, the invention disclosed in FIGURE 21 provides a very simple and straightforward electric generator driven directly by the rotation of the compressor and turbine shaft. Moreover, the location of the generator provides a very compact system, light in weight and not interfering with the operation of the system from which it derives its power. Therefore, the present invention provides a turbojet and turbofan arrangement wherein the combustion chamber is removed from the bearing assemblies used to support the compressor and turbine shaft. In another embodiment of the invention, the present invention incorporates an axial stage compressor on the opposite side of the bearing assemblies from a radial compressor. The invention also envisions the introduction of fuel into the turbojet system by supplying fuel directly through the radial compressor rotor from the compressor rotor shaft. In this embodiment, the fuel is ejected by centrifugal force and a fuel pump and accompanying hardware is eliminated. In the embodiment of the present invention providing for a turbofan, a bypass flow and a primary flow are provided. In accordance with one embodiment of this invention, an axial stage compressor is incorporated upstream and on opposite sides of the beariny assemblies from a radial compressor. The present invention also envisions the incorporation of a generator including an armature mounted on the end of the compressor and turbine shaft opposite the bearing assemblies from the compressor and turbine with a field winding mounted in the bearing support structure. This arrangement provides a very simple and straightforward generator for providing electrical power to the overall system. Although preferred embodiments of the invention have been described in the foreyoing detailed description and illustrated in the accompanying drawinys, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions of parts and elements without departing from the spirit of the invention. The present invention is therefore intended to encompass such rearrangements, modifications and substitutions of parts and elements as fall within the scope of the appended claims.

Claims: CLAIMS 1. A turbocharger housing with an inlet port (40) and a circumferential chamber (44) surroundiny said inlet port (40) and leading to a compressor exhaust port (52) in which housing, in use, a compressor rotor (160) is rotatably mounted for compressing air entering the inlet port (40) and discharging the compressed air into the chamber (44) for exhaust through the exhaust port (54), the outer housiny defining the inlet port (40) and the circumferential chamber (44) around the inlet port (40) and a wall insert (126) including a tubular throat (128) for engagement within the inlet port (40) and a disc (130) attached transversely at one end of the tubular throat (128), the disc (130) having an aperture corresponding to the opening of the throat (128) characterized by the inlet port (40) having an inside surface with a first portion (110) remote from the disc (130) having a varying diameter converging toward the disc (130) and a second portion (112) adjacent the disc (130) diverging in diameter toward the disc (130) and the tubular throat (128) having an inside surface (131) converging in diameter toward the disc (130) and an outside surface (132) diverging in diameter toward the disc (130) the outside surface being arranyed to mate with the second portion of the inside surface of the inlet port (40) of the outer housing. 2. The compressor housing according to Claim 1 characterized by means for attaching (140) said insert (126) within said outer housing with said insert forming one wall of the circumferential chamber (44) and forming a circumferential passageway between the aperture and the circumferential chamber (44) for channeliny compressed air from the aperture to the chamber (44). 3. The compressor housing according to Claim 1 or Claim 2 characterized by said attachment means comprising rivet protrusions (140) integrally formed and extending from the disc (130) and corresponding to and facing apertures in the wall of the outer housing circumferentially spaced around the inlet port (40), said rivet protrusions (140) being adapted for insertion into said apertures to join said insert (126) to said outer housing. 4. The compressor housing according to one of Claims 1 to 3 characterized by the inside surface (131) of the throat (128) of the wall insert (126) convering along a straight line at substantially the same rate as the first portion (110) of the inlet port inside surface converges to form a continuous converging surface from the end of the inlet port remote from the insert disc to the disc aperture. 5. The compressor housing according to one of Claims I to 4 characterized by: a bearing support cylinder (60); and a plurality of vanes (62) attached to and extending inwardly from the inside surface of the inlet port (40), said vanes (62) having a leading edge (330) remote from the disc (130) and a trailing edge (332) facing the disc (130), the leading and trailing edges (330, 332) being separated by a thicker intermediate vane section (336), the surfaces of said vanes (62) converging from the thickest intermediate vane section (336) to the leading and trailing edges (330, 332). 6. The compressor housing according to Claim 5 characterized by one end of the tubular throat (128) being notched (326) to correspond with the vanes (62) such that the throat (128) straddles the vanes (62) when the insert (126) is attached to the outer housing. 7. The compressor housing according to Claim 5 or Claim 6 characterized by three vanes (62) which extend substantially radially from said cylinder (60) to the inside wall of the housing, dividiny the inlet port (40) into three inlet passayes. 8. The compressor housing according to any one of Claims 1 to 7, characterized by the inlet port (40) being connected to the circumferential chamber (44) by a transverse wall (42). 9. The compressor housing according to any one of Claims 1 to 7, characterized by the inlet port diameter being shorter than the length of the inlet port (40). 10. The compressor housing according to any one of Claims 1 to 9, characterized by both the outer housing and the wall insert (126) being die cast. 11. A method of producing a compressor housing according to any one of Claims 1 to 10, comprising (i) die casting an outer housing (24) using an outer mold (290) having on it a protrusion, an inner mold (292) formed with a raised contour (298) to form the circumferential chamber and having a protrusion (300) for mating with the protrusion on the outer mold for forming the inlet port, a core mold (294), and acap mold (296) for cooperating with the core mold to form the exhaust port, (ii) die casting a compressor wall insert (126) using a pair of cooperating molds (320, 322) having abutting surfaces which engage one another to produce the wall insert with a parting line on the outer edge of the wall, and (iii) attaching said wall insert within said outer housing to form the compressor.

Inventors: OSBORN, NORBERT L., OSBORN, NORBERT LEWIS
Applicants: OSBORN, NORBERT L.
Application year: 1979
Main classification: F04D29
IPC codes: F04D29