Patent Publication Number: US-2022228525-A1

Title: Operation mechanism of turbocharger

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of PCT Application No. PCT/JP2020/030464, filed on Aug. 7, 2020, which claims the benefit of priority from Japanese Patent Application No. 2019-187109, filed on Oct. 10, 2019, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     A turbocharger such as that described in Japanese Patent No. 5845650 is known may be configured to control a pressure of air supplied to an internal combustion engine by including a bypass flow path which directly connects an exhaust gas inlet and an exhaust gas outlet of a turbine and a wastegate valve which opens and closes the bypass flow path. When the pressure of the air supplied to the internal combustion engine exceeds a predetermined value, the wastegate valve is opened so that a part of an exhaust gas supplied to the turbine is discharged through the bypass flow path. When a rod of an actuator moves forward and backward, a lever hinged to the tip of the rod swings and a rotation shaft of a valve body rotates so that the wastegate valve is opened and closed. 
     SUMMARY 
     An example operation mechanism of a turbocharger includes: a driving member configured to undergo a reciprocating movement; a link plate rotationally coupled to the driving member through a first hinge portion, wherein a first rotation center of the first hinge portion is configured to move linearly along a virtual line in a reciprocating manner in response to the reciprocating movement of the driving member; and an operation lever. The operation lever includes: a first end configured to operate a flow regulator of the turbocharger, wherein a swing center of the operation lever is located at the first end; and a second end rotationally coupled to the link plate through a second hinge portion including a second rotation center, wherein the second end of the operation lever is configured to swing relative to the swing center when the first rotation center moves linearly along the virtual line, and wherein a distance from the swing center to the second rotation center is shorter than a distance from the swing center to the virtual line. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of an example turbocharger. 
         FIG. 2  is a cross-sectional view showing the vicinity of an example wastegate valve. 
         FIG. 3  is an enlarged view of an example operation mechanism. 
         FIG. 4  is an exploded perspective view showing a fastening state between a joint member and a rod. 
         FIG. 5  is an enlarged view of an operation mechanism of a comparative example. 
         FIG. 6  is an enlarged view showing another state of the operation mechanism of the comparative example. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. 
     An example operation mechanism of a turbocharger includes: a driving member configured to undergo a reciprocating movement; a link plate rotationally coupled to the driving member through a first hinge portion, wherein a first rotation center of the first hinge portion is configured to move linearly along a virtual line in a reciprocating manner in response to the reciprocating movement of the driving member; and an operation lever. The operation lever includes: a first end configured to operate a flow regulator of the turbocharger, wherein a swing center of the operation lever is located at the first end; and a second end rotationally coupled to the link plate through a second hinge portion including a second rotation center, wherein the second end of the operation lever is configured to swing relative to the swing center when the first rotation center moves linearly along the virtual line, and wherein a distance from the swing center to the second rotation center is shorter than a distance from the swing center to the virtual line. 
     In some examples, the flow regulator may comprise a moving part configured to adjust a flow rate of a turbine. The movable part may be a valve body of a wastegate valve opened and closed by swinging the operation lever. In some examples, the turbocharger may further include an electric actuator generating the driving force. 
     In some examples, a swing range of the operation lever by the operation mechanism may be a range from a posture in which the rotation center of the second hinge portion is located on a perpendicular line drawn from the swing center to the virtual line to a posture in which the rotation center of the second hinge portion moves by a predetermined amount in a direction opposite to the first hinge portion. 
     Hereinafter, an example turbocharger will be described in detail with reference to the drawings.  FIG. 1  is a cross-sectional view of an example turbocharger  1  including a rotating axis H. The turbocharger  1  is applied to, for example, an internal combustion engine of a ship or a vehicle. 
     As shown in  FIG. 1 , the turbocharger  1  includes a turbine  2  and a compressor  3 . The turbine  2  includes a turbine housing  4  and a turbine impeller  6  accommodated in the turbine housing  4 . The turbine housing  4  includes a scroll flow path  16  which extends in the circumferential direction around the turbine impeller  6 . The compressor  3  includes a compressor housing  5  and a compressor impeller  7  accommodated in the compressor housing  5 . The compressor housing  5  includes a scroll flow path  17  extending in the circumferential direction around the compressor impeller  7 . 
     The turbine impeller  6  is provided at one end of a rotating shaft  14  and the compressor impeller  7  is provided at the other end of the rotating shaft  14 . A bearing housing  13  is provided between the turbine housing  4  and the compressor housing  5 . The rotating shaft  14  is rotatably supported by the bearing housing  13  through a bearing  15  and the rotating shaft  14 , the turbine impeller  6 , and the compressor impeller  7  rotate around the rotating axis H as an integral rotating body  12 . 
     The turbine housing  4  is provided with an exhaust gas inlet  8  and an exhaust gas outlet  10 . An exhaust gas discharged from an internal combustion engine flows into the turbine housing  4  through the exhaust gas inlet  8 , flows into the turbine impeller  6  through the scroll flow path  16 , and rotates the turbine impeller  6 . Then, the exhaust gas flows out of the turbine housing  4  through the exhaust gas outlet  10 . 
     The compressor housing  5  is provided with an inlet  9  and an outlet  11 . When the turbine impeller  6  rotates as described above, the compressor impeller  7  rotates through the rotating shaft  14 . The rotating compressor impeller  7  intakes external air through the inlet  9 . The air passes through the compressor impeller  7  and the scroll flow path  17  to be compressed and is discharged from the outlet  11 . The compressed air discharged from the outlet  11  is supplied to the above-described internal combustion engine. 
     As shown in  FIG. 2 , the turbocharger  1  includes a bypass flow path  31  and a wastegate valve  33 . The bypass flow path  31  directly connects the exhaust gas inlet  8  of the turbine  2  and the exhaust gas outlet  10 . The wastegate valve  33  is a flow regulator that opens and closes the bypass flow path  31 . By adjusting the opening degree of the wastegate valve  33 , the amount of the exhaust gas bypassing the turbine  2  is adjusted and the flow rate of the turbine  2  is adjusted. The pressure of the compressed air supplied to the internal combustion engine is adjusted by adjusting the flow rate of the turbine  2 . 
     As shown in  FIG. 3 , the turbocharger  1  includes an operation mechanism  35  for opening and closing the wastegate valve  33 . The operation mechanism  35  includes an electric actuator  37 , a joint member  39 , a link plate  41 , and an operation lever  43 . Hereinafter, as shown in each drawing, the X, Y, and Z directions orthogonal to each other are defined and used for convenience of description. X direction is a direction parallel to a direction along which a rod  37   b  (described in further detail later) extends and retracts. When the terms of “front” and “rear” are used, the +X direction to which the rod  37   b  extends is the front; and the −X direction to which the rod  37   b  retracts is the rear. Y direction is a direction parallel to a perpendicular line T (a second virtual line) drawn from a swing center  59  (described in further detail later) to an extension of the direction along which the rod  37   b  extends and retracts. When the terms of “up” and “down” are used, the +Y direction, a direction along the perpendicular line form the extension to the swing center  59 , is up; and the −Y direction, a direction along the perpendicular line T form the swing center  59  to the extension, is down. Hereinafter, the positional relationship and operation of each part of the operation mechanism  35  in a state of being projected on the XY plane will be described. 
     The operation lever  43  includes a rotation shaft  57  of a valve body  55  of the wastegate valve  33 . The rotation shaft  57  is provided at an upper end portion  43   a  (a first end) of the operation lever  43  and penetrates the turbine housing  4  to be connected to the valve body  55 . The operation lever  43 , the rotation shaft  57 , and the valve body  55  are relatively swingable or rotatable in the XY plane around the swing center  59  with respect to the turbine housing  4 . The swing center  59  of the operation lever  43  is located at the upper end portion  43   a.  The swing center  59  is also the center of the rotation shaft  57 . The upper end portion  43   a  is configured to operate the wastegate valve  33 . When the operation lever  43  rotates around the swing center  59  as described above, the valve body  55  rotates and the wastegate valve  33  is opened and closed. The valve body  55  of the wastegate valve  33  opens and closes when a lower end portion  43   b  (a second end) of the operation lever  43  swings relative to the swing center  59 . 
     The electric actuator  37  is a driving source that generates a driving force for swinging or rotating the operation lever  43 . The electric actuator  37  includes, for example, a main body portion  37   a  fixed to the turbine housing  4  and the rod (driving member)  37   b.  The rod  37   b  extends from the main body portion  37   a  in the +X direction. The rod  37   b  is configured to extend and retract in the +X direction with respect to the main body portion  37   a  in response to the driving force. 
     As shown in  FIG. 4 , the front end portion of the rod  37   b  is threaded and nuts  45  and  47  are screwed thereto. The rear end portion of the joint member  39  is provided with a flat plate portion  39   a  having a flat plate shape orthogonal to the X direction. The flat plate portion  39   a  is provided with a bolt hole (a hole)  39   b  penetrating in the X direction. The front end portion of the rod  37   b  is inserted through the bolt hole  39   b  of the flat plate portion  39   a  which is sandwiched between two nuts  45  and  47  in the front and rear direction. There is a clearance between the rod  37   b  and an upper edge of the bolt hole  39   b.  By tightening the nuts  45  and  47  in this state, the joint member  39  is fastened and fixed to the front end portion of the rod  37   b.  The position of the joint member  39  in the X direction with respect to the rod  37   b  may be adjusted by adjusting the screwing positions of the nuts  45  and  47  with respect to the rod  37   b.    
     As shown in  FIG. 3 , the link plate  41  is rotationally coupled to the rod  37   b  through a first hinge portion  51  located on the joint member  39 . The rear end portion of the link plate  41  is coupled to the front end portion of the joint member  39  through the first hinge portion  51 . The link plate  41  is relatively rotatable in the XY plane around a rotation center (a first rotation center)  51   a  of the first hinge portion  51  with respect to the joint member  39 . The front end portion of the link plate  41  is coupled to the lower end portion  43   b  of the operation lever  43  through a second hinge portion  52 . The lower end portion  43   b  rotationally coupled to the link plate  41  through the second hinge portion  52  including a rotation center (a second rotation center)  52   a.  The link plate  41  is relatively rotatable in the XY plane around the rotation center  52   a  of the second hinge portion  52  with respect to the operation lever  43 . 
     In the operation mechanism  35  with the above-described structure, the rod  37   b  is configured to undergo a reciprocating movement. When driving electric power is supplied to the electric actuator  37 , the rod  37   b  extends and retracts in the X direction by the driving force of the electric actuator  37 . The reciprocating movement causes the rod  37   b  to move between a retracted position P 1  (a first reciprocating position) and an extended position P 2  (a second reciprocating position) along a virtual line L parallel to the X direction. The virtual line L is aligned to the axis of the rod  37   b.  The joint member  39  moves in a reciprocating manner in the X direction in response to the reciprocating movement of the rod  37   b.  The rotation center  51   a  of the first hinge portion  51  is configured to move linearly along the virtual line L in a reciprocating manner in response to the reciprocating movement of the rod  37   b  and the joint member  39 . The driving force is transmitted to the second hinge portion  52  of the lower end portion  43   b  of the operation lever  43  through the link plate  41  by the reciprocating movement of the rod  37   b.  The operation lever  43  swings or rotates around the swing center  59  in response to the movement of the rotation center  52   a.  Accordingly, the valve body  55  rotates so that the wastegate valve  33  is opened and closed. The virtual line L is an extension of the direction along which the rod  37   b  extends and retracts. The wastegate valve  33  is configured to reduce the flow rate of the turbine  2  in response to a swing or rotation of the operation lever  43  by the operation mechanism  35  such that the second hinge portion  52  moves in a direction opposite to the rod  37   b.    
     The solid line in  FIG. 3  indicates a state in which the wastegate valve  33  is fully closed (hereinafter, simply referred to as a “fully closed state FC” as shown in  FIG. 2 ). The rotation center  52   a  of the second hinge portion  52  is located between the swing center  59  and the virtual line L when the rod  37   b  is located at the retracted position P 1 . For example, in the fully closed state FC, the rotation center  52   a  is located on the perpendicular line T drawn from the swing center  59  to the virtual line L. When the rod  37   b  of the electric actuator  37  extends in the +X direction from the posture of the operation lever  43 , the rotation center  52   a  moves in the +X direction and the operation lever  43  rotates in the counter-clockwise rotation direction in  FIG. 3 . As indicated by the two-dotted chain line in  FIG. 3 , the wastegate valve  33  is fully opened (hereinafter, simply referred to as a “fully open state”) in a state in which the rotation center  52   a  moves by a predetermined amount in the +X direction. 
     The swing range of the operation lever  43  by the operation mechanism  35  is the range from a posture (corresponding to the fully closed state FC) in which the rotation center  52   a  is located on the perpendicular line T drawn from the swing center  59  to the virtual line L to a posture (corresponding to the fully open state) in which the rotation center  52   a  moves by a predetermined amount in the direction opposite to the first hinge portion  51 . The rotation center  52   a  of the second hinge portion  52  is located on the perpendicular line T that passes through the swing center  59  and that is perpendicular to the virtual line L along which the first hinge portion  51  is configured to move when the rod  37   b  is located at the retracted position P 1 . The rotation center  52   a  is located off the perpendicular line T when the rod  37   b  is located at the extended position P 2 . For example, the movement range of the rotation center  52   a  by the operation mechanism  35  corresponds to the region on the front side of the perpendicular line T drawn from the swing center  59  to the virtual line L. The swing range of the operation lever  43  by the operation mechanism  35  is a region on the front side of the perpendicular line T drawn from the swing center  59  of the operation lever  43  to the virtual line L. 
     In the operation mechanism  35 , a distance from the swing center  59  of the operation lever  43  to the rotation center  52   a  of the second hinge portion  52  is shorter than a distance from the swing center  59  to the virtual line L. The rotation center  52   a  of the second hinge portion  52  is located between the swing center  59  and the virtual line L when the wastegate valve  33  is in the fully closed state FC. A difference between the distance from the swing center  59  to the rotation center  52   a  of the second hinge portion  52  and the distance from the swing center  59  to the virtual line L is larger than the clearance between the rod  37   b  and the upper edge of the bolt hole  39   b.  With this configuration, the rotation center  52   a  does not move to the region lower than the virtual line L by the swing of the operation lever  43 . In the fully closed state FC, the line connecting the rotation center  51   a  and the rotation center  52   a  is inclined with respect to the virtual line L. The line connecting the first hinge portion  51  and the second hinge portion  52  is inclined with respect to the virtual line L so that the second hinge portion  52  is farther away from the virtual line L than the first hinge portion  51 . 
     The operation and effect of the turbocharger  1  including the above-described operation mechanism  35  will be described in further detail. First, as a comparative example of the operation mechanism  35 , a case in which the distance from the swing center  59  of the operation lever  43  to the rotation center  52   a  of the second hinge portion  52  is set to be the same as the distance from the swing center  59  to the virtual line L is considered. In this setting, the line connecting the rotation center  51   a  and the rotation center  52   a  is orthogonal to the line connecting the swing center  59  and the rotation center  52   a  in the fully closed state FC. 
     However, according to this setting, the state shown in  FIG. 5  may occur due to factors such as a case in which the size of the operation lever  43  is slightly large due to the tolerance of the parts. Hereinafter, the operation mechanism in the state shown in  FIG. 5  is referred to as a comparative operation mechanism  135 . In the comparative operation mechanism  135 , the distance from the swing center  59  of the operation lever  43  to the rotation center  52   a  of the second hinge portion  52  is longer than the distance from the swing center  59  to the virtual line L. The rotation center  52   a  is located below the virtual line L in the fully closed state FC as shown in  FIG. 5 , but the rotation center  52   a  is located above the virtual line L in the fully open state as shown in  FIG. 6 . For example, the rotation center  52   a  of the comparative operation mechanism  135  moves upward or downward from the virtual line L by the opening and closing operation of the wastegate valve  33 . 
     The valve body  55  of the wastegate valve  33  receives the fluid force of the exhaust gas. The fluid force rotates the operation lever  43  in the counter-clockwise rotation direction in  FIGS. 5 and 6 . The force caused by the fluid force pulls the joint member  39  toward the second hinge portion  52  through the link plate  41 , For example, a force F indicted by an arrow in the drawing acts on the joint member  39 . The Y-direction component of the force F is directed upward when the rotation center  52   a  is located above the virtual line L (see  FIG. 6 ). The Y-direction component of the force F is directed downward when the rotation center  52   a  is located below the virtual line L (see  FIG. 5 ). 
     As shown in  FIGS. 5 and 6 , since the rotation center  52   a  is located above or below the virtual line L as described above in the comparative operation mechanism  135 , a force having an upward component and a force having a downward component alternately act on the joint member  39  during operation. When such a force repeatedly acts on the joint member  39 , there is a possibility that the fixed position of the joint member  39  with respect to the rod  37   b  may be displaced up and down. For example, the joint member  39  may be displaced up and down with respect to the rod  37   b  by sliding up and down against the fastening force of the nuts  45  and  47  by the clearance between the rod  37   b  and the bolt hole  39   b.    
     The correlation between the extension and retraction amount of the rod  37   b  and the rotation amount of the rotation shaft  57  may deviate or get out of synchronization. As a result, the opening and closing control of the wastegate valve  33  may become unstable in the comparative operation mechanism  135 . Since the turbocharger  1  adopts the electric actuator  37  to control the opening degree of the wastegate valve  33  accurately, the turbocharger tends to be affected by the slight displacement of the joint member  39  as described above. Since a force having an upward component and a force having a downward component alternately act on the joint member  39  as described above, the nuts  45  and  47  may be loosened. 
     On the other hand, according to the example operation mechanism  35  illustrated in  FIG. 3 , the rotation center  52   a  is set to be located above the virtual line L in advance in the fully closed state FC. This configuration allows the operation mechanism  35  to maintain the stability of the opening and closing control of the wastegate valve  33 . 
     Since the rotation center  52   a  is located in the region above the virtual line L as shown in  FIG. 3  in the operation mechanism  35 , the Y-direction component of the force F acting on the joint member  39  is directed upward. Even when the fixed position of the joint member  39  is displaced upward, the lower edge in the bolt hole  39   b  of the joint member  39  eventually hits the rod  37   b  and then the fixed position of the joint member  39  with respect to the rod  37   b  is stabilized. Thus, the stability of opening and closing control of the wastegate valve  33  can be maintained. When assembling the operation mechanism  35 , the joint member  39  may be assembled in advance so that the lower edge of the bolt hole  39   b  of the joint member  39  is in contact with the rod  37   b.  By tightening the nuts  45  and  47  in this state, the joint member  39  is fastened and fixed to the front end portion of the rod  37   b  in the state where the lower edge of the bolt hole  39   b  of the joint member  39  remains in contact with the rod  37   b  after the operation mechanism  35  is fully assembled. 
     It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail. 
     For example, in the above-described embodiments, an example of the operation mechanism  35  for opening and closing the wastegate valve  33  has been described, but the configuration of the operation mechanism  35  can be also applied to the operation mechanism of the other flow regulators of the turbocharger  1 . One of other flow regulators of the turbocharger  1  may be, for example, a nozzle of a variable nozzle mechanism that adjusts the flow rate of the turbine  2 . 
     We claim all modifications and variations coining within the spirit and scope of the subject matter claimed herein.