Turbocharger compressor with inlet adjustment mechanism having pivoting vanes forming an adjustable uninterrupted vane ring

Abstract

A turbocharger includes a compressor equipped with an inlet adjustment mechanism disposed in an air inlet of the compressor, the inlet adjustment mechanism including a plurality of arcuate blades distributed around a circumference and partially overlapping each other so as to form an uninterrupted 360-degree blade ring. Each blade is pivotable about a respective fixed pivot point so that the ring is adjustable between a maximum open position and a minimum open position, the ring being adjustable via simultaneous coordinated pivoting of the blades about the respective fixed pivot points. The blades are constructed and arranged to form the uninterrupted 360-degree blade ring in the maximum open position and the minimum open position and any intermediate position therebetween.

Description

Technical Field

[0001] The present disclosure relates to centrifugal compressors, such as those used in turbochargers, and more particularly to centrifugal compressors in which the effective inlet area or diameter can be adjusted for different operating conditions. Background Art

[0002] An exhaust-driven turbocharger is a device used in conjunction with an internal combustion engine to increase the power output of the engine by compressing air delivered to the engine intake for mixing with fuel and burning in the engine. A turbocharger includes a compressor wheel mounted on one end of a shaft in a compressor housing and a turbine wheel mounted on the other end of the shaft in a turbine housing. Typically, the turbine housing is formed separately from the compressor housing, and there is also another center housing connected between the turbine housing and the compressor housing for accommodating bearings for the shaft. The turbine housing defines a generally annular chamber surrounding the turbine wheel and receiving exhaust gases from the engine. The turbine assembly includes a nozzle that leads from the chamber to the turbine wheel. Exhaust gases flow from the chamber through the nozzle to the turbine wheel, and the turbine wheel is driven by the exhaust gases. Thus, the turbine extracts power from the exhaust gases and drives the compressor. The compressor receives ambient air through the inlet of the compressor housing, and the air is compressed by the compressor wheel and then discharged from the housing to the engine intake.

[0003] Turbochargers typically employ a centrifugal (also called "radial") type compressor impeller because centrifugal compressors can achieve relatively high pressure ratios in a compact arrangement. The compressor's intake air is received in a generally axial direction at an inlet portion of the centrifugal compressor impeller and is discharged in a generally radial direction at an outlet portion of the impeller. The compressed air from the impeller is delivered to a volute, and the air is supplied from the volute to the intake of the internal combustion engine.

[0004] The operating range of the compressor is an important aspect of the overall performance of the turbocharger. The operating range is usually defined by the surge line and the choke line on the compressor operating map. The compressor map is usually presented as the pressure ratio (exhaust pressure Pout divided by inlet pressure Pin) on the vertical axis and the corrected mass flow on the horizontal axis. The choke line on the compressor map is located at high flow and represents the locus of the maximum mass flow point over the pressure ratio range; that is, for a given point on the choke line, it is not possible to increase the flow while maintaining the same pressure ratio because a choke condition occurs in the compressor.

[0005] The surge line is located at low flows and represents the locus of the minimum mass flow points over the range of pressure ratios where there is no surge; that is, for a given point on the surge line, decreasing the flow without changing the pressure ratio, or increasing the pressure ratio without changing the flow, will cause surge to occur. Surge is a flow instability that typically occurs when the compressor blade incidence angle becomes so large that significant flow separation occurs over the compressor blades. Pressure fluctuations and reverse flow may occur during surge.

[0006] In turbochargers for internal combustion engines, compressor surge can occur when the engine is operated at high load or torque and low engine speed, or when the engine is operated at low speed and there is a high level of exhaust gas recirculation (EGR). Surge can also occur when the engine is suddenly decelerated from a high speed. Expanding the compressor's surge-free operating range for lower flows is a goal often sought in compressor design. Summary of the invention

[0007] The present disclosure describes a turbocharger having a centrifugal compressor, the turbocharger being equipped with an inlet adjustment mechanism operable to adjust the effective diameter of an air inlet that introduces air into a compressor impeller. During operating conditions where there is a risk of surge occurring, the inlet adjustment mechanism can be operated to reduce the effective diameter of the air inlet, which has the effect of increasing the flow velocity of the air entering the compressor impeller, thereby reducing the compressor blade incidence angle so as to delay the onset of surge to reduce flow.

[0008] According to one embodiment described herein, a turbocharger includes a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing receiving exhaust gas and supplying the exhaust gas to the turbine wheel; and a centrifugal compressor assembly including a compressor housing and a compressor wheel mounted in the compressor housing and connected to a rotatable shaft for rotation therewith. The compressor impeller defines an introduction portion, and the compressor housing has an air inlet wall defining an air inlet for introducing air generally axially into the compressor impeller. The compressor housing defines an annular space defined between an upstream wall and a downstream wall axially spaced therefrom, the annular space surrounding the air inlet and open to the air inlet at a radially inner end of the annular space.

[0009] A compressor inlet adjustment mechanism is disposed in an annular space of the compressor housing, the inlet adjustment mechanism comprising a plurality of coplanar arcuate blades distributed around a circumference and partially overlapping each other so as to form an uninterrupted 360-degree blade ring. Each blade is pivotable about a respective fixed pivot point so that the blade ring is adjustable between a maximum open position in which the inner diameter of the blade ring has a maximum value and a minimum open position in which the inner diameter of the blade ring has a minimum value. The blade ring is adjustable via simultaneous coordinated pivoting of the blades about respective fixed pivot points, and the blades are constructed and arranged to form the uninterrupted 360-degree blade ring in the maximum open position and the minimum open position and any intermediate positions therebetween.

[0010] In one embodiment, each of the blades includes a flow guide portion at one end of the blade, a lever arm at the opposite end of the blade, and a mounting portion disposed intermediate the lever arm and the flow guide portion. The flow guide portions of the blades collectively surround and form an inner diameter of the blade ring. The blades are completely within the annular space in the maximum open position of the blade ring. In any intermediate and minimum open positions of the blade ring, the blades are pivoted radially inwardly from the annular space into the air inlet, such that the effective diameter of the air inlet is reduced to a diameter defined by the inner diameter of the blade ring.

[0011] In some embodiments, the number of blades is at least five.

[0012] In a particular embodiment, the turbocharger further includes a unison ring surrounding the blades, the unison ring being rotatable about an axis of rotation substantially coaxial with the axis of rotation of the turbocharger. The unison ring has a radial inner periphery and a radial outer periphery, the radial outer periphery defining a plurality of circumferentially spaced notches, one notch for each of the blades. Alternatively, the notches may be defined in the radial inner periphery. Each blade is supported by a pivot pin connected to a mounting portion and engaged in a hole in the compressor housing so that the blade pivots about an axis defined by the pivot pin. The mounting portion of the blade is disposed radially inwardly from the radial inner periphery of the unison ring, and the lever arm of each blade includes a hook portion that engages in a corresponding notch in the notch in the unison ring. Thus, rotation of the unison ring imparts pivotal motion to the blade via engagement of the hook portion of the lever arm in the notch of the unison ring.

[0013] In embodiments in which the hook portion of the lever arm engages a notch in the radial periphery of the unison ring, the mounting portion of each blade may include a support pad on which the downstream face of the unison ring is axially supported.

[0014] In one embodiment, the guide portion of each blade defines a lower flange extending radially inwardly from the inner periphery of the unison ring and extending circumferentially toward the distal end of the guide portion of an adjacent blade of the blade, and the distal end of the guide portion of an adjacent blade of the blade defines a stepped portion having an overlying flange overlapping the lower flange. The lower flange and the overlying flange are constructed and arranged to at least partially overlap each other in all positions of the blade ring, thereby forming the uninterrupted 360-degree blade ring.

[0015] In one embodiment, the overlying flanges are disposed adjacent to the axially upstream faces of the underlying flanges, respectively.

[0016] In one embodiment, the vanes may collectively define a cylindrical duct extending axially within an annular space in the compressor housing, each vane defining an arcuate duct portion integrally formed on the vane, the duct portions of the vanes being connected end to end circumferentially around the annular space to form the cylindrical duct when the vane ring is adjusted to a minimum open position. The cylindrical duct formed when the vane ring is in the minimum open position helps to fluidly isolate the annular space from the compressor inlet and thereby helps to avoid flow disturbances at the impeller inlet that would otherwise be caused by the annular space. In other positions of the vane ring, the duct portions are separated from each other and therefore do not perform such a sealing function.

[0017] In one embodiment, the radially inner periphery of each vane comprises a circular arc, the vanes being constructed and arranged such that the radially inner peripheries of the vanes together form a substantially circular aperture in a minimum open position of the vane ring.

[0018] According to a particular embodiment, the compressor housing includes a main housing portion defining a volute and a profile, and a separately formed cover portion defining an air inlet, the cover portion being axially received in a receptacle defined by an upstream side of the main housing portion and secured to the main housing portion by fasteners, the upstream wall of the annular space being defined by the cover portion, and the downstream wall of the annular space being defined by the main housing portion.

[0019] The cover portion may define a contact pad that faces an upstream face of each of the vanes of the inlet regulating mechanism and constrains axial upstream movement of the vanes.

[0020] In one embodiment, the compressor housing defines a diffuser leading from an outlet portion of the compressor impeller to the volute, and the diffuser is a diverging diffuser. The diffuser is defined between an upstream diffuser wall and a downstream diffuser wall, and one of the upstream diffuser wall and the downstream diffuser wall is inclined relative to a radial direction so that the axial width of the diffuser increases with increasing radius from the rotation axis of the turbocharger. The inclined diffuser wall may be conical. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Having generally described the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0022] Figure 1 is an isometric view of a turbocharger according to one embodiment of the present invention as viewed from the compressor end generally toward the turbine end of the turbocharger;

[0023] Figure 2 As viewed from the compressor end toward the turbine end Figure 1 An end view of a turbocharger;

[0024] Figure 3 The turbocharger Figure 2 A cross-sectional view of line 2-2 in FIG.

[0025] Figure 4 is an exploded view of a turbocharger subassembly including a compressor housing and an inlet adjustment mechanism mounted therein;

[0026] Figure 4A is an isometric view of the cover portion showing a side of the cover portion facing the inlet adjustment mechanism;

[0027] Figure 5 is an isometric view of a blade of an inlet adjustment mechanism according to an embodiment of the present invention;

[0028] Figure 6 yes Figure 5 A further isometric view of the blade;

[0029] Figure 7 is an end view of a compressor according to an embodiment of the present invention showing the inlet adjustment mechanism in a minimum open position;

[0030] Figure 8 yes Figure 7 an end view of a compressor with a cover portion of the compressor housing removed to reveal details of the inlet adjustment mechanism;

[0031] Fig. 9 is along Figure 8 A cross-sectional view taken along line 9-9 in FIG.

[0032] Fig.10 yes Figure 7 An end view of the compressor of , showing the inlet adjustment mechanism in an intermediate open position;

[0033] Fig.11 yes Fig.10 an end view of a compressor with a cover portion of the compressor housing removed to reveal details of the inlet adjustment mechanism;

[0034] Fig.12 is along Fig.11 A cross-sectional view taken along line 12-12 in FIG.

[0035] Fig.13 yes Figure 7 an end view of a compressor of , showing the inlet regulating mechanism in a maximum open position;

[0036] Fig.14 yes Fig.13 an end view of a compressor of with a cover portion of the compressor housing removed to reveal details of the inlet adjustment mechanism; and

[0037] Fig.15 is along Fig.14 A cross-sectional view along line 15-15. DETAILED DESCRIPTION

[0038] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0039] In the present disclosure, the term "aperture" means "opening" regardless of the shape of the opening. Thus, an "aperture" may be circular or non-circular. Furthermore, when the present disclosure refers to blades collectively forming an "uninterrupted 360-degree blade ring," such language does not require physical contact between adjacent blades.

[0040] A turbocharger 10 according to an embodiment of the present invention is Figure 1 and Figure 2 and an axial cross-sectional view of the turbocharger is shown in Figure 3 . A turbocharger includes a compressor and a turbine. The compressor includes a compressor wheel or impeller 14 mounted in a compressor housing 16 on one end of a rotatable shaft 18. The compressor housing includes a wall defining an air inlet 17 for introducing air generally axially into the compressor wheel 14. The shaft is supported by bearings mounted in a center housing 20 of the turbocharger. The shaft is rotated by a turbine wheel 22 mounted on the other end of the shaft from the compressor wheel, thereby rotatably driving the compressor wheel, which compresses air drawn in through the compressor inlet and discharges the compressed air generally radially outward from the compressor wheel through a diffuser 19 into a volute 21 for receiving the compressed air. From the volute 21, the air is directed to the intake of an internal combustion engine (not shown) to improve the performance of the engine.

[0041] The turbine wheel 22 is disposed within a turbine housing 24 which defines an annular chamber 26 for receiving exhaust gases from an internal combustion engine (not shown). The turbine housing also defines a nozzle 28 for directing the exhaust gases from the chamber 26 generally radially inwardly to the turbine wheel 22. In the illustrated embodiment, the nozzle is a variable nozzle having a nozzle ring 34 on which a row of circumferentially spaced pivotable vanes 36 are supported. The flow of exhaust gases through the nozzle is adjusted by adjusting the position of the vanes 36. The exhaust gases expand as they pass through the turbine wheel and rotatably drive the turbine wheel, which in turn rotatably drives the compressor wheel 14, as already mentioned.

[0042] refer to Figure 1-4 In the illustrated embodiment, the wall defining the air inlet 17 for the compressor is formed in part by the compressor housing 16 (also referred to herein as the "main housing portion") and in part by a separate inlet duct member 16d (also referred to herein as the "cover portion"), which is received in a cylindrical seat 16r defined by the compressor housing. The portion of the air inlet 17 proximate the compressor impeller 14 defines a generally cylindrical inner surface 17i having a diameter that generally matches the diameter of the introduction portion 14i of the compressor impeller.

[0043] The compressor housing 16 defines a shroud surface 16s that is immediately adjacent the radially outer tips of the impeller blades. The shroud surface defines a curved profile that is generally parallel to the profile of the compressor impeller.

[0044] In the illustrated embodiment, the diffuser 19 leading from the outlet portion of the compressor impeller 14 to the volute 21 is a diverging diffuser whose axial width increases with increasing radius from the turbocharger rotation axis. The diffuser is defined between an upstream diffuser wall and a downstream diffuser wall, and one of the upstream diffuser wall and the downstream diffuser wall is inclined relative to the radial direction to produce a diverging diffuser. The inclined diffuser wall may be conical. In the illustrated embodiment, the downstream diffuser wall is inclined, but alternatively, the upstream wall may be inclined.

[0045] According to the present invention, the compressor of the turbocharger comprises an inlet adjustment mechanism 100 arranged in the air inlet 17 of the compressor housing. The inlet adjustment mechanism comprises an annular assembly and is arranged in an annular space S defined between a downstream wall 105d defined by the main housing portion 16 and an upstream wall 105u defined by a separate cover portion 16d. The inlet adjustment mechanism is operable to adjust the effective diameter of the air inlet entering the compressor impeller. Thus, the inlet adjustment mechanism is movable between a maximum opening position and a minimum opening position and between one or more intermediate opening positions between the maximum opening position and the minimum opening position.

[0046] Reference now Figure 3 and Figure 4 The inlet adjustment mechanism includes a plurality of vanes 102 arranged about the central axis of the air inlet, and each vane can pivot about a pivot pin 104 located at or near one end of the vane. The assembly of vanes 102 forms an uninterrupted 360 degree vane ring 103, the inner diameter of which can be adjusted via the pivoting of the vanes about the pivot pin.

[0047] Additional references Figure 5 and Figure 6 Each of the blades 102 includes a guide portion 102f at one end of the blade, a lever arm 102a at the opposite end of the blade, and a mounting portion 102m disposed between the lever arm and the guide portion. The guide portions 102f of the blades together surround and form the inner diameter of the blade ring. In the maximum open position, the blade is completely located within the annular space S ( Figure 3 ), and thus the inlet adjustment mechanism does not change the effective inlet diameter of the compressor, i.e. the inlet diameter is determined by the inlet surface 17i of the compressor housing immediately in front of the compressor impeller. In the intermediate open position and the minimum open position, the blade ring 103 forms an orifice with a diameter smaller than the diameter of the inlet surface 17i, and thereby reduces the effective inlet diameter relative to the nominal diameter, as further described below.

[0048] In the illustrated embodiment, a pivot pin 104 for the vane is fixed in a hole defined in a downstream wall 105d of the main housing portion 16 and is received in a hole 102h formed in a mounting portion of each vane. The vanes are arranged in close proximity to the downstream wall 105d. A boss 102b surrounding the hole 102h protrudes from the downstream face of each vane and engages with the downstream wall 105d so as to space most of the vane from the wall to minimize friction on the vane. The inlet adjustment mechanism further includes a unison ring 106 that surrounds the assembly of vanes 102 and is substantially coplanar with the vanes. In the illustrated embodiment, the radial periphery of the unison ring defines a plurality of cutouts or notches 108, the number of which is equal to the number of vanes 102. The lever arm 102a of each vane extends through the radial inner periphery to the radial outer periphery of the unison ring and includes an end or hook 102e that engages one of the cutouts 108, so that when the unison ring rotates about its axis, the vane pivots about the pivot pin 104 to adjust the size of the orifice created by the vane ring 103. In an alternative embodiment not shown, recesses for the blade lever arms are defined in the radially inner circumference of the unison ring.

[0049] The radially inner edges of the flow-guiding portions 102f of the blades comprise portions which are preferably arc-shaped, and these edges together surround and define a substantially circular orifice when the blade ring is in the minimum open position.

[0050] like Figure 4AAs shown in FIG. 1 , the cover portion 16 d in the illustrated embodiment defines a contact pad CP that faces the upstream face of each of the blades 102 of the inlet adjustment mechanism and constrains the axial upstream movement of the blades (see FIG. 1 ). Fig. 9 ). Accordingly, each blade includes a contact pad CP' for contacting a corresponding one of the contact pads of the cover portion, such as Figure 5 as shown in .

[0051] In an alternative embodiment (not shown), the inlet adjustment mechanism may be provided in the form of a cartridge comprising two annular end plates between which the vanes and unison ring are captively retained, and the entire assembly may be mounted in an annular space within the compressor casing. In this case, the pivot pin 104 of the vane 102 may be fixed in one of the end plates.

[0052] The range of pivotal movement of the blades is sufficient to enable the blades to be pivoted radially outwardly (by rotation of the unison ring in one direction, Figure 8 Clockwise in the Fig.14 , where the vanes are completely radially outside of the inlet inner surface 17i. As previously mentioned, in the maximum open position of the vanes, the inlet adjustment mechanism does not change the nominal inlet diameter as defined by the inlet surface 17i.

[0053] The blades can also be pivoted radially inwards (by coordinating the rotation of the ring in the opposite direction, Fig.14 counterclockwise in the Figure 8 . In the minimum open position, the arcuate edges along the radially inner side of the vanes together form an orifice that is substantially circular with a diameter that is smaller than the diameter of the inlet surface 17i. This results in a reduction in the effective diameter of the inlet relative to the nominal inlet diameter. In addition, in the illustrated embodiment, the vanes can be pivoted to at least one intermediate open position, such as Fig.10 and 11 In the intermediate open position, the blade ring 103 defines an orifice whose diameter is greater than the diameter of the minimum open position, but still smaller than the diameter of the inlet surface 17i.

[0054] A feature of the present invention is that in all positions of the blade ring 103, the blades 102 together form an uninterrupted 360 degree blade ring. This is achieved by the number, structure and arrangement of the blades 102 and the position of their pivot pins 104 relative to the rest of the blade, as further described below. Therefore, reference is made to Figure 5 and Figure 6, the proximal end of the guide portion 102f of each blade (the terms "proximal" and "distal" are relative to the position of the pivot pin 104 of the blade) defines a lower flange 102u extending from a point adjacent to the hole 102h for the pivot pin toward the distal end of the guide portion (i.e., in a generally radially inward direction when the blade is installed as part of the blade ring 103). The lower flange 102u also extends circumferentially toward the distal end of the guide portion of an adjacent blade in the blade. Accordingly, the distal end of the guide portion of the adjacent blade in the blade defines a stepped portion having an overlying flange 102o that overlaps with the lower flange 102u of the first blade. The lower flange and the overlying flange are constructed and arranged to at least partially overlap each other in all positions of the blade ring, thereby forming the uninterrupted 360 degree blade ring (see Fig.14 102o is disposed adjacent the axially upstream face of the underlying flange 102u. The ability of the blades to form an uninterrupted blade ring in all positions depends in part on the number of blades. Preferably, there are at least five blades; the illustrated embodiment employs six blades, but a greater number of blades may be used if desired.

[0055] In the illustrated embodiment, each of the blades 102 defines an arcuate duct portion 102d integrally formed on the blade. Figure 8 ), the duct portion 102d of the blade is connected end to end in the circumferential direction around the annular space S in the compressor housing to form a cylindrical duct D extending axially in the annular space in the compressor housing, adjacent to the radial inner end ( Fig. 9 ). The cylindrical duct, which is formed only when the blade ring is in the minimum open position, helps to fluidically isolate the annular space from the compressor inlet and can thereby help to avoid flow disturbances at the impeller inlet that would otherwise be caused by the annular space. In other positions of the blade ring, the duct portions are separated from each other and therefore do not perform such a sealing function.

[0056] As previously described, the vanes 102 are actuated to pivot between their maximum open position, minimum open position, and intermediate open position by a unison ring 106 rotatable about the central axis of the air inlet. Figure 4, rotational motion is imparted to the unison ring by an actuator 116. An actuator rod 117 of the actuator is received in a receptacle 116a defined in the compressor housing 16. The actuator includes an arm 118 extending through a space defined in the compressor housing and fixed at its distal end to an arm 118, which extends radially outwardly from the unison ring through an elongated aperture 119 extending through the wall of the compressor housing. The actuator is operable to linearly extend and retract the rod 117 along its length so as to rotate the unison ring 106 and thereby actuate the vanes 102. Extending the rod pivots the vanes toward a minimum open position and retracting the rod pivots the vanes toward a maximum open position.

[0057] As described above, the inlet adjustment mechanism 100 is capable of adjusting the effective size or diameter of the inlet into the compressor impeller 14. Figure 7 and Figure 8 As shown in , when the inlet adjustment mechanism is in the minimum open position, the effective diameter of the inlet into the compressor impeller is determined by the inner diameter defined by the blade ring 103. To achieve this effect, the axial spacing should be optimized for the specific compressor impeller so that the inlet diameter is effectively reduced to the value determined by the blade ring while avoiding unacceptable noise levels.

[0058] At low flow rates (e.g., low engine speeds), the inlet adjustment mechanism 100 may be placed Figure 7 and Figure 8 The compressor will then be moved to its minimum open position. This may have the effect of reducing the effective inlet diameter, and thereby increasing the flow velocity entering the compressor impeller. The result will be a reduced angle of incidence to the impeller blades, effectively stabilizing the flow (i.e., making impeller blade stall and compressor surge less likely). In other words, the compressor surge line will shift to lower flows (to the left on a plot of compressor pressure ratio versus flow).

[0059] At medium and high flow rates, the inlet adjustment mechanism 100 may be adjusted to a maximum open position, such as Fig.13 and Fig.14 This can have the effect of increasing the effective inlet diameter so that the compressor essentially recovers its high flow performance and choke flow as if the inlet adjustment mechanism did not exist and as if the compressor had a conventional inlet at the lead-in portion of the impeller that matched the impeller diameter.

[0060] For other operating conditions, it may be advantageous to place the mechanism in an intermediate open position, such as in Fig.10 and Fig.11Intermediate positions may be advantageous, for example when transiently moving from a low flow state to a high flow state, wherein the blade ring may transition from a minimum open position to one or more intermediate open positions on the way to a fully open to maximum open position. In this way, a sudden change from the minimum open position to the maximum open position may be avoided. It should be noted that an advantage of the inlet regulating mechanism according to the invention, wherein the number of blades is preferably at least 5, is that the shape of the orifice formed by the blades in the intermediate position may be substantially circular, which is beneficial to the performance of the compressor. The relatively large number of blades further facilitates a reduction in leakage through the mechanism.

[0061] Based on this disclosure, those skilled in the art will recognize that modifications and other embodiments may be made to the invention described herein without departing from the inventive concept described herein. Specific terms used herein are for illustrative purposes rather than limiting purposes. Therefore, the present invention is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims.

Claims

1. A turbocharger, comprising: a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing receiving exhaust gas and supplying the exhaust gas to the turbine wheel; a centrifugal compressor assembly including a compressor housing and a compressor impeller mounted in the compressor housing and connected to the rotatable shaft for rotation therewith, the compressor impeller including impeller blades and defining an introduction portion, the compressor housing having an air inlet wall defining an air inlet for introducing air generally axially into the compressor impeller, the compressor housing further defining a profile disposed adjacent radially outer tips of the impeller blades and defining a volute for receiving compressed air discharged generally radially outwardly from the compressor impeller, the compressor housing defining an annular space defined between an upstream wall and a downstream wall axially spaced therefrom, the annular space surrounding the air inlet and being open to the air inlet at a radially inner end of the annular space; as well as A compressor inlet regulating mechanism, which is arranged in the annular space of the compressor housing, the inlet regulating mechanism includes a plurality of coplanar arcuate blades, the plurality of coplanar arcuate blades are distributed around a circumference and partially overlap each other so as to form an uninterrupted 360-degree blade ring, wherein each blade includes a guide portion at one end of the blade, a lever arm at the opposite end of the blade, and a mounting portion arranged between the lever arm and the guide portion, the mounting portion of the blade defines a corresponding fixed pivot point for the blade, the blade can pivot around the corresponding fixed pivot point, so that the blade ring is between a maximum open position in which the inner diameter of the blade ring has a maximum value and a minimum open position in which the inner diameter of the blade ring has a minimum value. The blade ring is adjustable in the maximum open position, the blade ring is adjustable via simultaneous coordinated pivoting of the blades about the corresponding fixed pivot points, the guide portions of the blades jointly surround and form the inner diameter of the blade ring, the blades are completely located within the annular space in the maximum open position of the blade ring, when the blade ring is in any of the intermediate and minimum open positions, the blades are radially pivoted inwardly from the annular space into the air inlet so that the effective diameter of the air inlet is reduced to the diameter defined by the inner diameter of the blade ring, and wherein the blades are constructed and arranged to form the uninterrupted 360 degree blade ring in the maximum open position and the minimum open position and any intermediate open positions therebetween.

2. The turbocharger according to claim 1, wherein: The number of the blades is at least 5.

3. The turbocharger according to claim 2, further comprising: a unison ring surrounding the vanes, the unison ring being rotatable about an axis of rotation substantially coaxial with an axis of rotation of the turbocharger, the unison ring defining a plurality of circumferentially spaced apart notches defined in one of a radially inner periphery and a radially outer periphery of the unison ring, one notch for each vane, each vane is supported by a pivot pin connected to the mounting portion and engages in a hole in the compressor housing so that the vane pivots about an axis defined by the pivot pin, the mounting portion of the vane being disposed radially inwardly from the radially inner periphery of the unison ring, the lever arm of each vane including a hook at a radially outer end of the lever arm that engages in a corresponding one of the recesses in the unison ring, Thus, rotation of the unison ring imparts pivotal movement to the vane via engagement of the hook portion of the lever arm in the recess in the unison ring.

4. The turbocharger according to claim 3, wherein: The notch is defined in the radially outer periphery of the unison ring.

5. The turbocharger according to claim 4, wherein: The mounting portion of each blade includes a support pad on which the downstream face of the unison ring is axially supported.

6. The turbocharger according to claim 3, wherein: The proximal end of the guide portion of each blade defines a lower flange extending radially inward from the inner periphery of the coordination ring and extending circumferentially toward the distal end of the guide portion of an adjacent blade among the blades, and wherein the distal end of the guide portion of the adjacent blade among the blades defines a step portion having an overlying flange overlapping the lower flange, and wherein the lower flange and the overlying flange are constructed and arranged to at least partially overlap each other in all positions of the blade ring, thereby forming the uninterrupted 360-degree blade ring.

7. The turbocharger according to claim 6, wherein: The upper flange and the axial upstream faces of the lower flange are respectively arranged adjacent to each other.

8. The turbocharger according to claim 6, wherein: Each blade defines an arcuate duct portion integrally formed on the blade, and when the blade ring is adjusted to the minimum open position, the duct portions of the blades are connected end to end circumferentially around the annular space to form a cylindrical duct near the radial inner end of the annular space in the compressor housing and extending axially within the annular space.

9. The turbocharger according to claim 6, wherein: The radially inner periphery of each vane comprises a circular arc, the vanes being constructed and arranged such that the radially inner peripheries of the vanes together form a substantially circular aperture in the minimum open position of the vane ring.

10. The turbocharger according to claim 6, wherein: The compressor housing includes a main housing portion defining the volute and the profile, and a separately formed cover portion defining the air inlet, the cover portion being axially received in a receptacle defined by an upstream side of the main housing portion and secured to the main housing portion by fasteners, the upstream wall of the annular space being defined by the cover portion, and the downstream wall of the annular space being defined by the main housing portion.

11. The turbocharger according to claim 10, wherein: The cover portion defines a contact pad that faces an upstream face of the vane of the inlet adjustment mechanism and constrains axial upstream movement of the vane.

12. The turbocharger according to claim 11, wherein: The compressor housing defines a diffuser leading from an outlet portion of the compressor impeller to the volute, and wherein the diffuser is a diverging diffuser.

13. The turbocharger according to claim 12, wherein: The diffuser is defined between an upstream diffuser wall and a downstream diffuser wall, and the upstream diffuser wall is inclined relative to a radial direction such that an axial width of the diffuser increases with increasing radius from the rotational axis of the turbocharger.

14. The turbocharger according to claim 13, wherein: The upstream diffuser wall is conical.

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