Abstract:
An apparatus for controlling an exhaust attack angle for a variable turbine applied in a turbocharger of an engine is provided that comprises: an actuator driven according to a strength of a supplied current; one or more vanes rotatably installed at the perimeter of a turbine; and a transmission assembly that is linked to said actuator, which converts linear motion of the actuator to rotational motion and transmits the rotational motion to the vane in order to rotate the vane, thereby varying the exhaust attack angle based on the strength of the supplied current.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus for controlling the exhaust attack angle of a variable turbine, and more particularly, to an apparatus for controlling the exhaust attack angle of a turbine blade of a variable turbine that is installed in the exhaust side of a turbocharger.  
         BACKGROUND OF THE INVENTION  
         [0002]    Generally, a diesel engine uses a turbocharger system to increase the pressure of the air drawn by the engine. The turbocharger is operated by exhaust gas in order to pressurize, or boost, intake air. In a conventional turbocharger system, the rotating speed of the turbine is determined by the amount of exhaust gas from the exhaust manifold. When an engine is rotating slowly it produces less exhaust and, thus, the intake air cannot be compressed because the exhaust pressure is low. The turbine also resists rotating faster through friction and inertia. Consequently, at times, the torque developed by the engine may not be satisfactory due to low boost pressure.  
         SUMMARY OF THE INVENTION  
         [0003]    In a preferred embodiment of the present invention, an apparatus controls the attack angle of the exhaust or the turbine to use the discharge speed of the exhaust more efficiently. The apparatus for controlling the exhaust attack angle of a variable turbine applied in a turbocharger of an engine comprises an actuator, one or more vanes, and a transmission assembly. The actuator is driven according to a strength of a supplied current. The vanes are rotatably installed at the perimeter of a turbine and the transmission assembly is linked to said actuator. The transmission assembly converts linear motion of the actuator to rotational motion and transmits the rotational motion to the vane in order to rotate the vane.  
           [0004]    In a further preferred embodiment, the actuator comprises a current amplifier, an expansion and contraction part, and an operating rod. The current amplifier outputs a current signal after amplifying an input current signal to a specific magnitude. The expansion and contraction part preferably comprises a shape-memory alloy and its ends are connected to a positive terminal and a negative terminal of the current amplifier, which provides the expansion and contraction part with a current. The operating rod is connected to an end of the expansion and contraction part in order to be linked with expansion and contraction motion of the expansion and contraction part. Preferably, the expansion and contraction part has the form of a spring. It is also preferable that ends of the expansion and contraction part are respectively provided with a positive terminal plate and a negative terminal plate, and that these terminal plates are connected to corresponding terminals of the current amplifier.  
           [0005]    In another preferred embodiment, the actuator further comprises a tube case with a through-hole into which the expansion and contraction part is inserted. Preferably, the operating rod and the tube case are composed of a ceramic material.  
           [0006]    In a further preferred embodiment, the actuator is installed on an equipped bracket which is connected to a turbine case.  
           [0007]    In an additional preferred embodiment of the present invention, the transmission assembly comprises an outer crank, a rotating plate, an inner crank, a rotating ring, and one or more rotary cams. The outer crank is connected to the actuator to be linked with the actuator to be operated. One end of the rotating plate is connected to the outer crank. The inner crank is connected to the other end of the rotating plate in order to rotate. The rotating ring is installed inside the turbine case in order to be rotatable in conjunction with rotation of a driving cam formed at one end of the inner crank. The rotary cams are respectively installed in one or more grooves formed along the inner circumference of the rotating ring, to be linked with rotation of the rotating ring, of which one end is connected to the vane by way of a rotary shaft. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    A preferred embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings in which:  
         [0009]    [0009]FIG. 1 is a partial sectional perspective view of a variable turbine of the present invention;  
         [0010]    [0010]FIG. 2 is a schematic view of an apparatus for controlling an exhaust attack angle for a variable turbine according to the present invention;  
         [0011]    [0011]FIG. 3 is a detailed schematic view of an actuator applied in an apparatus for controlling the exhaust attack angle for a variable turbine according to the present invention; and  
         [0012]    [0012]FIG. 4 is a schematic view of a general turbocharger system. 
     
    
       [0013]    Like numerals refer to similar elements throughout the several drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    In a turbocharger system, as shown generally in FIG. 4, a turbine  101  of a turbocharger  105  is connected to an exhaust manifold  109  and supplied with exhaust gas from an engine  107 . A blower  103  is connected to an intake system to supply the engine  107  with intake air, by pushing intake air through an intercooler  113  and an intake manifold  115  after drawing the intake air from an air cleaner  111  through an intake duct  119 . The turbine  101  is connected to the blower  103  through a rotary shaft  121 , and the rotary shaft  121  is supported by journal bearings (not shown). The pressure of the exhaust gas causes the turbine  101  to rotate. An exhaust duct  117  receives the discharge exhaust gas from the turbine  101 . The blower  103 , which is connected to the turbine through the rotary shaft  121 , rotates and compresses the intake air from the air cleaner  111 , sending it into the intake manifold  115  after passing it through the intercooler  113 .  
         [0015]    In FIG. 1, a variable turbine  1  of the present invention includes a turbine case  7  that comprises an exhaust gas supply pipe  5 , which supplies exhaust gas from an exhaust manifold of an engine (not shown). The variable turbine also includes a turbine blade  9  connected to a blower  3  by way of a rotary shaft  11 , and a cover  13  that covers the turbine.  
         [0016]    In FIG. 2, an actuator  17  connects through bracket  15  to one side of the outside of the cover  13 . A front stage of an operating rod  19  of the actuator  17  is connected to one end of a rotating plate  25  by an outer crank  21 , and the other end of the rotating plate  25  is connected to one end of an inner crank  23  that is rotatably installed in one side of the cover  13 . A rotating ring  27 , which is rotatable with respect to the cover  13 , engages one side of a driving cam  29  that is provided at the other end of the inner crank  23 . Driving cam  29  rotates with inner crank  23 , causing rotating ring  27  to rotate as well.  
         [0017]    Rotating ring  27  also contains a plurality of cam grooves  31  that are formed at regular intervals along the inner circumference of the ring. A plurality of rotary cams  33  are respectively provided in grooves  31 , with the ends of a plurality of rotary shafts  35  connected to each rotary cam  33 . The other end of each rotary shaft  35  is connected to a vane  37 , each of which is arranged at a regular interval at the perimeter of the turbine  9 .  
         [0018]    As shown in FIG. 3, the actuator  17  is constructed with a current amplifier  41  at the top end of the equipped bracket  15 . Amplifier  41  amplifies an electric signal input from an engine control unit (not shown) and outputs a current signal. A driving part  43 , provided at the bottom of the current amplifier, moves the operating rod  19  up and down according to the current signal output by the current amplifier  41 . The driving part  43  of the actuator  17  includes a tube case  45  that is installed below the current amplifier  41  and a positive terminal plate  47 , which is connected to the positive terminal of the current amplifier  41 . The tube case  45  is fixed in place with respect to amplifier  41  and is preferably formed of a ceramic material. A negative terminal plate  49  is installed below the tube case  45  to be movable along the inside thereof, and it is connected to the negative terminal of the current amplifier  41 . The operating rod  19  is then connected to the bottom of the negative terminal plate  49 . A spring  51 , composed of a shape-memory alloy, is located between the positive terminal plate  47  and the negative terminal plate  49  inside the tube case  45 , and it is respectively connected to the terminal plates  47  and  49 . The spring  51  contracts or expands according to the current supplied to the spring  51 . The shape-memory alloy is an alloy of which the shape returns to an original shape when it is heated over a specific transition temperature. Examples of such include a nickel-titanium alloy, a copper-zinc-aluminum alloy, and so forth. When a varying current is supplied to the spring produced from the shape-memory alloy, the spring  51  is heated according to the variation of the current and the spring  51  may contract or expand. In the apparatus for controlling the exhaust attack angle according to the present embodiment, the shape-memory alloy is formed in the shape of a spring, but one of ordinary skill in the art will recognize that the shape-memory alloy may take other shapes.  
         [0019]    The apparatus functions in the following manner. When the engine is running at a high speed, or revolutions per minute (rpm), the current amplifier  41  receives an electric signal corresponding to the high rpm, from the engine control unit (not shown). Current amplifier  41  outputs a current signal to the spring  51  that is proportional to the input current, heating spring  51  with the current conducted therethrough. The spring  51  then contracts in length and pulls one side of the rotating plate  25  by way of the outer crank  21 . This causes the inner crank  23 , that is connected to the other side of the rotating plate  25 , to rotate the rotating ring  27  in a high rpm direction by way of the driving cam  29 . By rotating the rotating ring  27 , each vane  37  is rotated by its corresponding rotary cam  33  and rotary shaft  35 . This changes the exhaust attack angle (X) such that the incidence angle of exhaust gas supplied to the turbine blade  9  is lessened, thereby supplying less exhaust gas pressure to the turbine vanes.  
         [0020]    Conversely, when the engine is running at a low rpm, the current amplifier  41  receives an electric signal, corresponding to the low rpm, from the engine control unit (not shown). Current amplifier  41  outputs a corresponding decreased current signal to the spring  51 . The spring  51  then cools and expands in length, pushing one side of the rotating plate  25  by way of the outer crank  21 . This causes the inner crank  23  that is connected to the other side of the rotating plate  25 , to rotate the rotating ring  27  in a low rpm direction by way of the driving cam  29 . By rotating the rotating ring  27 , each vane  37  is rotated by its corresponding rotary cam  33  and rotary shaft  35 . This changes the exhaust attack angle (X) such that the incidence angle of exhaust gas supplied to the turbine  9  is increased, thereby supplying more exhaust gas pressure to the turbine vanes.  
         [0021]    Although the incidence angle of the exhaust gas is not shown here, the changes in the exhaust attack angle (X) cause the exhaust gas to be glancingly incident upon the turbine at a high rpm, and directly incident upon the turbine at a low rpm. Consequently controlling the power of the turbine.  
         [0022]    As described above, with the apparatus for controlling the exhaust attack angle for a variable turbine according to the present invention, the angle of the vanes installed in the variable turbine can be precisely and automatically controlled so that the efficiency of the engine power can be maximized. While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.