Apparatus for controlling exhaust attack angle for a variable turbine

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.

FIELD OF THE INVENTION

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

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

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.

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.

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.

In a further preferred embodiment, the actuator is installed on an equipped bracket which is connected to a turbine case.

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.

Like numerals refer to similar elements throughout the several drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a turbocharger system, as shown generally inFIG. 4, a turbine101of a turbocharger105is connected to an exhaust manifold109and supplied with exhaust gas from an engine107. A blower103is connected to an intake system to supply the engine107with intake air, by pushing intake air through an intercooler113and an intake manifold115after drawing the intake air from an air cleaner111through an intake duct119. The turbine101is connected to the blower103through a rotary shaft121, and the rotary shaft121is supported by journal bearings (not shown). The pressure of the exhaust gas causes the turbine101to rotate. An exhaust duct117receives the discharge exhaust gas from the turbine101. The blower103, which is connected to the turbine through the rotary shaft121, rotates and compresses the intake air from the air cleaner111, sending it into the intake manifold115after passing it through the intercooler113.

InFIG. 1, a variable turbine1of the present invention includes a turbine case7that comprises an exhaust gas supply pipe5, which supplies exhaust gas from an exhaust manifold of an engine (not shown). The variable turbine also includes a turbine blade9connected to a blower3by way of a rotary shaft11, and a cover13that covers the turbine.

InFIG. 2, an actuator17connects through bracket15to one side of the outside of the cover13. A front stage of an operating rod19of the actuator17is connected to one end of a rotating plate25by an outer crank21, and the other end of the rotating plate25is connected to one end of an inner crank23that is rotatably installed in one side of the cover13. A rotating ring27, which is rotatable with respect to the cover13, engages one side of a driving cam29that is provided at the other end of the inner crank23. Driving cam29rotates with inner crank23, causing rotating ring27to rotate as well.

Rotating ring27also contains a plurality of cam grooves31that are formed at regular intervals along the inner circumference of the ring. A plurality of rotary cams33are respectively provided in grooves31, with the ends of a plurality of rotary shafts35connected to each rotary cam33. The other end of each rotary shaft35is connected to a vane37, each of which is arranged at a regular interval at the perimeter of the turbine9.

As shown inFIG. 3, the actuator17is constructed with a current amplifier41at the top end of the equipped bracket15. Amplifier41amplifies an electric signal input from an engine control unit (not shown) and outputs a current signal. A driving part43, provided at the bottom of the current amplifier, moves the operating rod19up and down according to the current signal output by the current amplifier41. The driving part43of the actuator17includes a tube case45that is installed below the current amplifier41and a positive terminal plate47, which is connected to the positive terminal of the current amplifier41. The tube case45is fixed in place with respect to amplifier41and is preferably formed of a ceramic material. A negative terminal plate49is installed below the tube case45to be movable along the inside thereof, and it is connected to the negative terminal of the current amplifier41. The operating rod19is then connected to the bottom of the negative terminal plate49. A spring51, composed of a shape-memory alloy, is located between the positive terminal plate47and the negative terminal plate49inside the tube case45, and it is respectively connected to the terminal plates47and49. The spring51contracts or expands according to the current supplied to the spring51. 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 spring51is heated according to the variation of the current and the spring51may 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.

The apparatus functions in the following manner. When the engine is running at a high speed, or revolutions per minute (rpm), the current amplifier41receives an electric signal corresponding to the high rpm, from the engine control unit (not shown). Current amplifier41outputs a current signal to the spring51that is proportional to the input current, heating spring51with the current conducted therethrough. The spring51then contracts in length and pulls one side of the rotating plate25by way of the outer crank21. This causes the inner crank23, that is connected to the other side of the rotating plate25, to rotate the rotating ring27in a high rpm direction by way of the driving cam29. By rotating the rotating ring27, each vane37is rotated by its corresponding rotary cam33and rotary shaft35. This changes the exhaust attack angle (X) such that the incidence angle of exhaust gas supplied to the turbine blade9is lessened, thereby supplying less exhaust gas pressure to the turbine vanes.

Conversely, when the engine is running at a low rpm, the current amplifier41receives an electric signal, corresponding to the low rpm, from the engine control unit (not shown). Current amplifier41outputs a corresponding decreased current signal to the spring51. The spring51then cools and expands in length, pushing one side of the rotating plate25by way of the outer crank21. This causes the inner crank23that is connected to the other side of the rotating plate25, to rotate the rotating ring27in a low rpm direction by way of the driving cam29. By rotating the rotating ring27, each vane37is rotated by its corresponding rotary cam33and rotary shaft35. This changes the exhaust attack angle (X) such that the incidence angle of exhaust gas supplied to the turbine9is increased, thereby supplying more exhaust gas pressure to the turbine vanes.

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.

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.