Abstract:
A variable geometry turbocharger is provided. The turbocharger improves efficiency by controlling flow to the rotor ( 230 ) via movable vanes ( 260 ). The vanes ( 260 ) can be rotated using a pin ( 380, 480 ) and groove ( 385, 485 ) system. The vanes ( 260 ) can be multiple structures ( 710, 730 ) that are movable with respect to each other to increase the length of each of the vanes ( 260 ). The turbocharger also improves efficiency by creating a better seal in the area between the vanes ( 260 ) and the adjustment ring ( 240 ). The seal can be provided by biasing the adjustment ring ( 240 ) towards each of the vanes ( 260 ). The seal can be provided by expanding each of the vanes ( 260 ). The seal can be provided by having a movable portion ( 1150 ) of the adjustment ring ( 240 ) that is actuated by a pressure source or the like and axially moves towards the vanes ( 260 ). The plurality of vanes ( 260 ) can be low solidity vanes.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates in general to turbochargers and, more particularly, to variable geometry turbochargers. 
       BACKGROUND OF THE INVENTION 
       [0002]    Turbochargers are widely used on internal combustion engines and, in the past, have been particularly used with large diesel engines, especially for highway trucks and marine applications. 
         [0003]    More recently, in addition to use in connection with large diesel engines, turbochargers have become popular for use in connection with smaller, passenger car power plants. The use of a turbocharger in passenger car applications permits selection of a power plant that develops the same amount of horsepower from a smaller, lower mass engine. Using a lower mass engine has the desired effect of decreasing the overall weight of the car, increasing sporty performance, and enhancing fuel economy and reducing the aerodynamic drag of the vehicle. Moreover, use of a turbocharger permits more complete combustion of the fuel delivered to the engine, thereby reducing the overall emissions of the engine, which contributes to the highly desirable goal of a cleaner environment. 
         [0004]    The design and function of turbochargers are described in detail in the prior art, for example, U.S. Pat. Nos. 4,705,463, 5,399,064, and 6,164,931, the disclosures of which are incorporated herein by reference. 
         [0005]    Turbocharger units typically include a turbine operatively connected to the engine exhaust manifold, a compressor operatively connected to the engine air intake system, and a shaft connecting the turbine and compressor so that rotation of the turbine wheel causes rotation of the compressor impeller. The turbine is driven to rotate by the exhaust gas flowing from the exhaust manifold. The compressor impeller is driven to rotate by the turbine, and, as it rotates, it increases the air mass flow rate, airflow density, air pressure and temperature delivered to the engine cylinders. 
         [0006]    As the use of turbochargers finds greater acceptance in passenger car applications, three design criteria have moved to the forefront. First, the market demands that all components of the power plant of either a passenger car or truck, including the turbocharger, must provide reliable operation for a much longer period than was demanded in the past. That is, while it may have been acceptable in the past to require a major engine overhaul after 80,000-100,000 miles for passenger cars, it is now necessary to design engine components for reliable operation in excess of 150,000 miles of operation. It has been necessary to design engine components in trucks for reliable operation in excess of 1,000,000 miles of operation for some time. This means that extra care must be taken to ensure proper design and fabrication and cooperation of all supporting devices. 
         [0007]    The second design criterion that has moved to the forefront is that the power plant must meet or exceed very strict requirements in the area of minimized NO x  and particulate matter emissions. Third, with the mass production of turbochargers, it is highly desirable to design a turbocharger that meets the above criteria and is comprised of a minimum number of parts. Further, those parts should be easy to manufacture and easy to assemble, in order to provide a cost effective and reliable turbocharger. 
         [0008]    Turbocharger efficiency over a broad range of operating conditions is enhanced if the flow of motive gas to the turbine wheel can be modulated. One method for achieving this level of control is to make the vanes pivotable so as to alter the geometry of the passages therebetween. The design of the mechanism used to effect pivoting of the vanes is critical to prevent binding of the vanes. Other considerations include the cost of manufacture of parts and the labor involved in assembly of such systems. 
         [0009]    Additionally, the design of the vane is critical to both the efficiency of the gas delivery to the turbine, as well as the reliability of the variable geometry assembly. While movement of the vanes allows for control of the gas delivery, it also adds the problem of leakage past the moveable vanes. Additionally, due to the extreme environment that the moveable vanes are placed in, the structure of the vanes, especially where pivotally connected via vane posts and the like, must be sound to avoid failure. 
         [0010]    In U.S. Published Application 20050207885 to Daudel, the Applicants attempt to control fluid delivery to the compressor wheel by providing movable guide vanes. As shown in  FIG. 1 , a variable diffuser geometry  13  on a rear compressor wall  14  comprises a plurality of annularly arranged guide vanes  16  which are uniformly distributed over the circumference and each of which includes a guide vane shaft  17 . The guide vane shaft  17  of each guide vane  16  is pivotally supported in a support ring  18  which is surrounded by an adjustment ring  19 . The radially inner end of the adjustment ring  19  is rotatably supported on the radially outer circumference of the support ring  18 . The adjustment ring  19  includes a plurality of adjustment elements  20  in the form of pins arranged at an axial front side of the adjustment ring  19 . The adjustment ring  19  is engaged by an adjustment member  21  in the form of an operating rod for rotating the adjustment ring  19 . 
         [0011]    The Daudel adjustment member  21  is operated by an actuator  21 ′. The adjustment member  21  is capable of rotating the adjustment ring  19 , so that the adjustment elements  20  are moved circumferentially by a certain angle whereby the guide vanes  16  on the support ring  18  are pivoted by a corresponding angle about their guide vane shaft  17 . Each guide vane  16  is fork-like shaped with two spaced fork tines  22  and  23  disposed at their outer ends between which a radially outwardly open engagement channel is formed into which the adjustment element  20  extends in any position of the adjustment ring  19 . During an adjustment movement of the adjustment ring  19  in the direction of the arrow  25 , the guide vanes  16  can be guided in any position of the adjustment ring  19 . 
         [0012]    The Daudel system suffers from the drawback of requiring a complicated system with numerous parts. The Daudel system further suffers from the drawback of only allowing for a particular range of motion for control of the fluid flow. 
         [0013]    In U.S. Pat. No. 6,679,057 to Arnold, the Applicant attempts to control flow to the volute by providing movable guide vanes. As shown in  FIG. 2 , the Arnold system has a turbocharger  110  with a turbine housing  112  adapted to receive exhaust gas from an internal combustion engine and distribute the exhaust gas to an exhaust gas turbine wheel or turbine  114  rotatably disposed within the turbine housing  112  and coupled to one end of a common shaft  116 . The turbine housing  112  encloses a variable geometry member  117  that comprises a plurality of pivotably moving vanes  118  disposed therein. A turbine adjustment or unison ring  119  is positioned within the turbine housing  112  adjacent the vanes  118  to engage the vanes and effect radially inward and outward movement of the vanes vis-a-vis the turbine in unison. The turbine unison ring  119  comprises a plurality of slots  120  disposed therein that are configured to provide a minimum backlash and a large area contact when combined with correspondingly shaped tabs  122  that project from each of the turbine vanes  118 . The turbine unison ring  119  is rotatably positioned within the housing, and is configured to engage and rotate turbine vanes through identical angular movement. 
         [0014]    The turbine unison ring  119  comprises an elliptical slot  123  that is configured to accommodate placement of an actuator pin  124  therein for purposes of moving the unison ring within the housing. The pin  124  is attached to one end of an actuator lever arm  126 , that is attached at its other opposite end an actuator crank  128 . The turbine actuating pin  124  and lever arm  126  are each disposed within a portion of the turbocharger center housing  130  adjacent the turbine housing. The actuator crank  128  is rotatably disposed axially through the turbocharger center housing  130 , and is configured to move the lever arm  126  back and forth about an actuator crank longitudinal axis, which movement operates to rotate the actuating pin  124  and effect rotation of the unison ring  119  within the turbine housing. Rotation of the unison ring  119  in turn causes the plurality of turbine vanes to be rotated radially inwardly or outwardly vis-a-vis the turbine  114  in unison. 
         [0015]    The turbocharger  110  also comprises a compressor housing  131  that is adapted to receive air from an air intake  132  and distribute the air to a compressor impeller  134  rotatably disposed within the compressor housing  131  and coupled to an opposite end of the common shaft  116 . The compressor housing also encloses a variable geometry member  136  interposed between the compressor impeller and an air outlet. The variable geometry member is in the form of radial diffuser and comprises a plurality of pivoting vanes  138 . A compressor adjustment or unison ring  140  is rotatably disposed within the compressor housing  131  and is configured to engage and rotatably move all of the compressor vanes  138  in unison. The compressor unison ring  140  comprises a plurality of slots  142  disposed therein that are each configured to provide a minimum backlash and a large area contact when combined with correspondingly shaped tabs  144  projecting from each respective compressor vane. The compressor unison ring  140  effects rotation of the plurality of compressor vanes  138  through identical angular movement. 
         [0016]    The compressor adjustment ring  140  comprises a slot and an actuating pin  146  that is rotatably disposed within the slot. An actuating lever arm  148  is attached at one of its end to the actuating pin  146 , and is attached at another one of its ends to an end of the actuator crank  128  opposite the turbine unison ring lever arm  126 . The compressor unison ring actuating pin  146  and lever arm  148  are disposed through a backing plate  150  that is interposed between the turbocharger compressor housing  131  and the center housing  130 . The actuator crank  128  is rotatably disposed through the center housing  130 . Rotation of the actuator crank  128  causes the compressor unison actuating lever arm  148  to move around a longitudinal axis of the actuator crank, which in turn effects rotation of the compressor unison ring actuating pin  146 . Rotation of the actuating pin  146  causes the compressor unison ring  140  to rotate along the backing plate  150 , which in turn causes each of the compressor vanes  138  to be pivoted radially inwardly or outwardly vis-a-vis the compressor impeller  134 . 
         [0017]    The Arnold system suffers from the drawback of requiring a complicated system with numerous parts. The Arnold system further suffers from the drawback of only allowing for a particular range of motion for control of the fluid flow. 
         [0018]    Thus, there is a need for a variable geometry system that effectively and efficiently controls fluid flow from the compressor wheel. There is a further need for such a system that is reliable and cost-effective. There is yet a further need for such a system that facilitates assembly of the turbocharger. 
       SUMMARY OF THE INVENTION 
       [0019]    The present disclosure provides an efficient and cost-effective system for controlling fluid from the compressor impeller of a turbocharger. The system facilitates assembly of the turbocharger by reducing the requirement for precision fit. The system further improves efficiency by creating a better seal between the vanes and the mating surfaces against which they control the airflow. 
         [0020]    In one aspect of the invention, a turbocharger is provided comprising a compressor housing; a compressor rotor rotatably mounted in the compressor housing; a supply channel for supplying a compressible fluid from the compressor rotor; and a vane ring assembly having an adjustment ring and a plurality of vanes. The plurality of vanes are distributed in an annular vane space and are movable to control flow of the compressible fluid. The vane angle of attack can be changed using a variety of methods. The plurality of vanes ( 260 ) can be low solidity vanes. 
         [0021]    In another aspect, a turbocharger is provided comprising: a housing; a rotor rotatably mounted in the housing; a supply channel for supplying a fluid to the rotor; and a vane ring assembly having first and second nozzle rings. The first nozzle ring is fixed with respect to the turbocharger and has a plurality of first vanes. The second nozzle ring is rotatable with respect to the turbocharger and has a plurality of second vanes. Each of the plurality of first and second vanes is distributed in an annular vane space. Each of the plurality of first and second vanes is non-rotatable with respect to the first and second nozzle rings. The second nozzle ring is rotatable from a first position to a second position. In the first position, the plurality of first vanes are aligned with the plurality of second vanes. In the second position, the plurality of first vanes are non-aligned with the plurality of second vanes. 
         [0022]    In another aspect, a turbocharger is provided comprising: a housing; a rotor rotatably mounted in the housing; a supply channel for supplying a fluid to the rotor; and a vane ring assembly having an adjustment ring and a plurality of vanes. The plurality of vanes are distributed in an annular vane space and are movable to control flow of the fluid. Each of the plurality of vanes is connected to the turbocharger by a rotatable pin. The adjustment ring has a sealing portion that is axially movable towards the plurality of vanes. The sealing portion is in communication with an actuator. The actuator causes the sealing portion to move towards the plurality of vanes to reduce a gap therebetween. 
         [0023]    The turbocharger may further comprise a biasing mechanism that biases the adjustment ring towards the plurality of vanes. The biasing mechanism can be a spring. The biasing mechanism may be a plurality of springs. The turbocharger can further comprise a biasing mechanism that biases each of the plurality of vanes towards the adjustment ring. Each of the plurality of vanes can be first and second portions that are moveable with respect to each other, and the biasing mechanism can expand each of the plurality of vanes. 
         [0024]    The biasing mechanism may be at least one spring positioned between the first and second portions. The biasing mechanism can be a compressible material. The turbocharger can further comprise a biasing mechanism that biases the first and second nozzle rings towards the plurality of first and second vanes. The actuator can be a pressure source in communication with the sealing portion via a channel. The pressure source may be pneumatic or hydraulic. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a plan view of a variable geometry compressor of a turbocharger according to U.S. Published Patent Application No. 20050207885; 
           [0026]      FIG. 2  is a cross-sectional view of another variable geometry compressor of a turbocharger according to U.S. Pat. No. 6,679,057; 
           [0027]      FIG. 3  is a cross-sectional view of a portion of a variable geometry compressor according to an exemplary embodiment of the invention; 
           [0028]      FIG. 4   a  is a cross-sectional view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0029]      FIG. 4   b  is a plan view of a vane used with the variable geometry compressor of  FIG. 4   a;    
           [0030]      FIG. 5   a  is a cross-sectional view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0031]      FIG. 5   b  is a plan view of a vane used with the variable geometry compressor of  FIG. 5   a;    
           [0032]      FIG. 6   a  is a cross-sectional view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0033]      FIG. 6   b  is a plan view of a vane used with the variable geometry compressor of  FIG. 6   a;    
           [0034]      FIG. 7  is a cross-sectional view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0035]      FIG. 8  is a plan view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0036]      FIG. 9  is a plan view of a portion a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0037]      FIG. 10  is a plan view of a portion of the variable geometry compressor of  FIG. 9  in a second position; 
           [0038]      FIG. 11   a  is a cross-sectional view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0039]      FIG. 11   b  is a cross-sectional view of the variable geometry compressor of  FIG. 11   a  in a biased state; 
           [0040]      FIG. 12   a  is a perspective view of a vane of a variable geometry compressor according to another exemplary embodiment of the invention; 
           [0041]      FIG. 12   b  is a perspective view of the vane of  FIG. 12   a  in an un-biased state; 
           [0042]      FIG. 13  is a cross-sectional view of a portion of a variable geometry compressor according to another exemplary embodiment of the invention; and 
           [0043]      FIG. 14  is a schematic representation a variable geometry compressor according to another exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    Exemplary embodiments described herein are directed to a variable geometry compressor system for a turbocharger. Aspects will be explained in connection with several possible embodiments of the system, but the detailed description is intended only as exemplary. The particular type of turbocharger that utilizes the exemplary embodiments of the vane and vane assemblies described herein can vary. The several embodiments are described with respect to vanes for the compressor wheel. Exemplary embodiments are shown in  FIGS. 3-14 , but the present disclosure is not limited to the illustrated structure or application. In one embodiment, the moveable guide vanes are low solidity vanes (i.e., low ratio of gap to chord). For example, the low solidity can be less than one. 
         [0045]    A portion of a turbocharger system as shown in  FIG. 3  includes turbomachinery in the form of a compressor housing  210 , a bearing housing  220 , a compressor wheel  230 , an adjustment ring  240  and a flow channel  250 . The flow channel or vane space  250  has a series of guide vanes  260  that allow for control of flow therethrough and thus adjustment of flow to the compressor wheel  230 . The adjustment force for the vane  260  is applied at region  270 , while the pivot point is along a pin or other rotation mechanism  265 . The particular size or shape of each of the vanes  260  can be chosen based upon a number of factors including flow efficiency. The embodiment of  FIG. 3  uses a single bearing, which is pin  265 . However, the present disclosure contemplates the use of bearings on both sides of the vanes  260 . 
         [0046]      FIGS. 4   a  and  4   b  show a variable geometry compressor system having the compressor housing  210 , the adjustment ring  240  and the flow channel  250 . The adjustment force for the vane  360  is applied at region  270 , while the pivot point is along the pin or other rotation mechanism  265 . An adjustment pin  380  is connected to the adjustment ring  240  and is housed in a groove  385  of the vane  360 . Annular movement of the adjustment ring  240  and thus adjustment pin  380  causes selective sliding of the pin within groove  385  and rotation of the vane  360 . 
         [0047]      FIGS. 5   a  and  5   b  show a variable geometry compressor system having the compressor housing  210 , the adjustment ring  240  and the flow channel  250 . The adjustment force for the vane  460  is applied at region  270 , while the pivot point is along the pin or other rotation mechanism  265 . An adjustment pin  480  is connected to the vane  460  and is housed in a groove  485  of the adjustment ring  240 . Annular movement of the adjustment ring  240  and thus groove  485  causes selective sliding of the pin within groove  485  and rotation of the vane  460 . 
         [0048]      FIGS. 6   a  and  6   b  show a variable geometry compressor system having the compressor housing  210 , the adjustment ring  240  and the flow channel  250 . The adjustment force for the vane  560  is applied at region  270 , while the pivot point is along the pin or other rotation mechanism  265 . A pair of opposing adjustment pins or a fork  580  abuts the vane  560  and is connected to the adjustment ring  240 . Annular movement of the adjustment ring  240  and thus fork  580  causes rotation of the vane  560  about the axis defined by pin  265 . 
         [0049]    Rotation of the adjustment ring  240  for the above-described embodiments can be by various structures and techniques including gear pairing, lever mechanisms and/or chain drives. Various sizes and shapes can be used for the components described above including the grooves, pins and forks based upon various factors including flow efficiency and effecting selected motion of the vanes  560 . 
         [0050]      FIG. 7  shows a variable geometry compressor system having the compressor housing  210 , the adjustment ring  240  and the flow channel  250 . The adjustment force for the vane  660  is applied along the pin or other rotation mechanism  665 . For example, an adjustment moment can be applied to pin  665  via a gear  670  operably connected to an actuation device  680 . Rotation of the adjustment ring  240  causes rotation of the gear  670  due to its connection to the actuation device  680 . 
         [0051]      FIG. 8  shows a variable geometry compressor system that allows for change of angle of attack or profile of the vane set. The system has a first fixed nozzle ring  700  having a series of fixed guide vanes  710  attached thereto and a second rotatable nozzle ring  720  having a series of fixed guide vanes  730  attached thereto. Rotation of the ring  720  allows for changing of the position of the vanes  730  and thus changing of the angle of attack of the total vane structure. The un-aligned position of the vanes  730  is shown by dashed lines  735 . The embodiment of  FIG. 8  provides for an adjustment of the operating point while reducing the number of moving parts. While the system of  FIG. 8  has two nozzle rings, the present disclosure contemplates the use of more than two rings which can be various combinations of moveable and non-movable rings for adjustment of the position of each of the vanes  710 ,  730  with respect to each other. 
         [0052]      FIGS. 9 and 10  show a variable geometry compressor system that allows for adjustment of the vane effective chord lengths. The system has a vane comprising first, second and third portions  800 ,  810 ,  820 . Portions  800 ,  810  and  820  are connected to an actuation device, such as an adjustment ring  850 , that allow for movement of the vane portions  800 ,  810 ,  820  along path  830 . The extended vane structure is shown in  FIG. 10 . The embodiment of  FIGS. 9 and 10  provides for an adjustment of the vane effective chord length in a synchronized manner for flow control to the compressor wheel. While the system of  FIGS. 9 and 10  has three portions  800 ,  810 , and  820  that are movable with respect to each other, the present disclosure contemplates the use of two or more movable vane portions. 
         [0053]    In the embodiment of  FIGS. 11   a  and  11   b , efficiency of flow control is enhanced by reducing the gap loss resulting at the forward end of the vane, adjacent to the leading edge of the vane. Vane  900  is adjustably positioned with respect to adjustment ring  240  through use of pin  265 . A biasing mechanism, such as spring  910 , is utilized to bias the adjustment ring towards the vane  900  to reduce or eliminate any gap  905  between the ring and the vane. The particular type of biasing mechanism  910 , e.g., a spring, and the amount of force applied can be selected so as to ensure movement of the vane while minimizing any gap. The number and configuration of the biasing mechanisms can be chosen to efficiently reduce or eliminate any gap  905  while still allowing for movement of the vanes  900 , such as, for example, a plurality of equidistantly spaced springs  910  to spread the biasing force with respect to the adjustment ring  240 . The adjustment mechanism can be on either the bearing housing side of the vane, or on the compressor housing side of the vane. 
         [0054]    In the embodiment of  FIGS. 12   a  and  12   b , efficiency of flow control is enhanced by reducing the gap losses in the area adjacent to the leading edge of the vane. Vane  1000  is adjustably positioned with respect to an adjustment ring through use of a pin  265  or the like. A biasing mechanism, such as spring  1010 , is utilized to bias the vane toward the adjustment ring and/or compressor housing to reduce or eliminate any gap therebetween. The particular type of biasing mechanism  1010  and the amount of force applied can be selected so as to ensure movement of the vane while minimizing any gap. The biasing spring  1010  can be one or more springs positioned within separate housings or portions  1015 ,  1020  of the vane to expand the width of the vane as desired. The biasing mechanism  1010  can also be a compressible or expandable foam or other material applied between the separate housings or portions  1015 ,  1020 . 
         [0055]    In the embodiment of  FIG. 13 , efficiency of flow control is enhanced by reducing the gap loss in the area adjacent to the leading edge of the vanes. Vane  1100  is adjustably positioned with respect to an adjustment ring  240  through use of a pin  265  or the like. A movable ring segment  1150  is utilized to reduce or eliminate any gap between the vane and the adjustment ring. The ring segment  1150  is moveably connected to the adjustment ring  240  by bearings  1160  and the like, and can be axially moved by various sources including a pneumatic or hydraulic source in communication with the segment through supply channel  1175 . Movement of the segment  1150  against or in proximity to the vane  1100  can also reduce any gap between the vane and the compressor housing  210 . Variations of the pressure supplied through channel  1175  can dynamically adjust the vane gaps as needed. The present disclosure also contemplates movement of the segment  1150  by other means such as electrical controllers, springs or mechanical actuators. 
         [0056]      FIG. 14  shows a variable geometry compressor system having a flexible vane  1200  that is connected to the turbocharger by a rotatable pin  265  or the like. The pin  265  is rigidly connected to the vane  1200  and can be connected to the compressor housing and/or adjustment ring. Pins or a fork  1220  abuts against the vane  1200 . A rotational force  1210  applied to pin  265  causes flexing of the vane into the shape shown by dashed line  1250 . It should be understood that features of the various exemplary embodiments can be interchangeable with one another. The foregoing description is provided in the context of exemplary embodiments of vanes and vane assemblies for a turbocharger. Thus, it will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the following claims.