Turbocharger turbine stage valves controlled by a single actuator

A turbocharger (1) including a twin scroll turbine and a valve assembly (40, 140) disposed in the exhaust gas inlet (24, 124) that is configured to control the flow exhaust gas through the turbine. The valve assembly (40, 140) includes two rotary valves (60, 160, 80, 180) actuated by a common valve shaft (44, 144). One of the valves (60, 180) may control exhaust gas flow to a volute or between volutes, and the other (80, 160) may control wastegate exhaust gas flow. The valve shaft (44, 144) is driven by an actuator to rotate about the valve shaft rotational axis (46, 146) such that the first valve (60, 160) and the second valve (80, 180) can each be selectively moved between a closed position and an open position, and the time sequence order of opening of the first valve (60, 160) and the second valve (80, 180) is selectable.

BACKGROUND

A turbocharger is a type of forced induction system used with internal combustion engines. Turbochargers typically include a turbine housing connected to the engine's exhaust manifold, a compressor housing connected to the engine's intake manifold, and a centrally located bearing housing coupling the turbine and compressor housings together. A turbine wheel in the turbine housing is rotatably driven by an inflow of exhaust gas supplied from the exhaust manifold. A shaft rotatably supported in the bearing housing connects the turbine wheel to a compressor impeller in the compressor housing so that rotation of the turbine wheel causes rotation of the compressor impeller. As the compressor impeller rotates, it increases the air mass flow rate, airflow density and air pressure delivered to the engine's cylinders via the engine's intake manifold.

Turbochargers deliver compressed air to an engine intake, allowing more fuel to be combusted, thus boosting an engine's horsepower without significantly increasing engine weight. Thus, turbochargers permit the use of smaller engines that develop the same amount of horsepower as larger, naturally aspirated engines. Using a smaller engine in a vehicle has the desirable effect of decreasing the mass of the vehicle, increasing performance, and enhancing fuel economy. Moreover, the use of turbochargers permits more complete combustion of the fuel delivered to the engine, which reduces undesirable emissions.

SUMMARY

In some aspects, a turbocharger that is configured to be connected to an engine includes a turbine section. The turbine section includes a turbine wheel, and a turbine housing that encloses the turbine wheel and defines an exhaust gas inlet, an exhaust gas outlet, a first turbine volute disposed between the exhaust gas inlet and the turbine wheel and a second turbine volute disposed between the exhaust gas inlet and the turbine wheel. The first and second turbine volutes are separated by a dividing wall. The turbine section includes a bypass passage that permits communication between the exhaust gas inlet and the exhaust gas outlet and bypasses the turbine wheel, a first valve configured to control flow through a first port that communicates with the second turbine volute, a second valve configured to control flow through a second port that communicates with the bypass passage and a valve shaft including a rotational axis. The valve shaft is connected to both the first valve and the second valve, and is driven by an actuator to rotate about the rotational axis such that the first valve and the second valve can each be selectively moved between a closed position and an open position, and the time sequence order of opening of the first valve and the second valve is selectable.

The turbocharger may include one or more of the following features: The first valve opens at a different time than the second valve. The first valve and the second valve are rotary valves. The exhaust gas inlet includes an inlet flange including a first flange opening and a second flange opening, a first passage that extends between the first flange opening and the first turbine volute, a second passage that extends between the second flange opening and the second turbine volute and a valve housing disposed in the exhaust gas inlet between the inlet flange and the first and second turbine volutes. The valve housing includes a connecting chamber including the first port and a third port, the first port connecting the connecting chamber and the second passageway, and the third port connecting the connecting chamber and the first passageway. The valve housing includes a wastegate chamber that communicates with the bypass passage, the wastegate chamber including the second port and a fourth port, the second port connecting the wastegate chamber and the first passage, and the fourth port connecting the wastegate chamber and the second passage. The first valve is configured to control flow through the first port and the third port, and the second valve is configured to control flow through the second port and the fourth port. The connecting chamber and the wastegate chamber are disposed on opposed sides of the exhaust gas inlet. When the first valve is in an open position, the first passage communicates with the second passage via the connecting chamber.

In addition, the turbocharger may include one or more of the following additional features: The exhaust gas inlet includes an inlet flange including a flange opening, a first passage that extends between the flange opening and the first turbine volute, a second passage that communicates with the second turbine volute, and a valve housing disposed in the exhaust gas inlet between the inlet flange and the first and second turbine volutes. The valve housing includes a connecting chamber that communicates with the second passage, the connecting chamber including the first port that connects the connecting chamber and the flange opening, and a wastegate chamber that communicates with the bypass passage, the wastegate chamber communicating with the connecting chamber via valve openings of the second valve. When the first valve is in an open position and the second valve is in closed position, the second passage communicates with the flange opening and a portion of gas flowing through the flange opening can flow to the second turbine volute via the second passage. When the first valve is in an open position and the second valve is in an open position, a portion of gas flowing through the flange opening is diverted to the bypass passage via the first port and the second port. In addition, when the first valve and the second valve are in a closed position, all gas flowing through the flange opening is directed to the first passage.

In some aspects, a turbocharger that is configured to be connected to an engine includes a turbine section including a turbine wheel and a turbine housing that encloses the turbine wheel. The turbine housing defines an exhaust gas inlet, an exhaust gas outlet, a first turbine volute disposed between the exhaust gas inlet and the turbine wheel, and a second turbine volute disposed between the exhaust gas inlet and the turbine wheel. The first and second turbine volutes are separated by a dividing wall. The exhaust gas inlet includes an inlet flange including a first flange opening and a second flange opening, a first passage that extends between the first flange opening and the first turbine volute, a second passage that extends between the second flange opening and the second turbine volute, and a valve housing disposed in the exhaust gas inlet between the inlet flange and the first and second turbine volutes. The valve housing includes a and a second connecting port that communicates with the second passage, and a wastegate chamber having a first wastegate port that communicates with the first passage and a second wastegate port that communicates with the second passage. The valve housing includes a first valve configured to control flow through the first connecting port and the second connecting port, a second valve configured to control flow through the first wastegate port and the second wastegate port, and a valve shaft including a rotational axis. The valve shaft is connected to both the first valve and the second valve, and is driven by an actuator to rotate about the rotational axis such that the first valve and the second valve can each be selectively moved between a closed position and an open position, and the time sequence order of opening of the first valve and the second valve is selectable.

The turbocharger may include one or more of the following features: The wastegate chamber includes a third wastegate port that communicates with the exhaust gas outlet. The connecting chamber and the wastegate chamber are disposed on opposed sides of the exhaust gas inlet. When the first valve is in an open position, the first passage communicates with the second passage via the connecting chamber.

In some aspects, a turbocharger that is configured to be connected to an engine includes a turbine section. The turbine section includes a turbine wheel and a turbine housing that encloses the turbine wheel. The turbine housing defines an exhaust gas inlet, an exhaust gas outlet, a first turbine volute disposed between the exhaust gas inlet and the turbine wheel, and a second turbine volute disposed between the exhaust gas inlet and the turbine wheel. The first and second turbine volutes separated by a dividing wall. The exhaust gas inlet includes an inlet flange including a flange opening, a first passage that extends between the flange opening and the first turbine volute, a second passage that communicates with the second turbine volute, and a valve housing disposed in the exhaust gas inlet between the inlet flange and the first and second turbine volutes. The valve housing includes a connecting chamber having a first connecting port that communicates with flange opening and a second connecting port that communicates with the second passage. The valve housing includes a wastegate chamber having a first wastegate port that communicates with the connecting chamber and a second wastegate port that that communicates with exhaust gas outlet. The valve housing also includes a first valve configured to control flow through the first connecting port, a second valve configured to control flow through the first wastegate port, and a valve shaft including a rotational axis, the valve shaft connected to both the first valve and the second valve. The valve shaft is driven by an actuator to rotate about the rotational axis such that the first valve and the second valve can each be selectively moved between a closed position and an open position, and the time sequence order of opening of the first valve and the second valve is selectable.

The turbocharger may include one or more of the following features: The second connecting port and the second wastegate port are valve-free. When the first valve is in an open position and the second valve is in closed position, the second passage communicates with the flange opening and a portion of gas flowing through the flange opening can flow to the second turbine volute via the second passage. When the first valve is in an open position and the second valve is in an open position, a portion of gas flowing through the flange opening is diverted to the bypass passage via first connecting port and the second port; and the second wastegate port. When the first valve and the second valve are in a closed position, all gas flowing through the flange opening is directed to the first passage.

In some aspects, a turbocharger that is configured to be connected to an engine includes a turbine stage and a compressor stage. The turbine stage includes a turbine wheel and a turbine housing that encloses the turbine wheel. The turbine housing defines a twin scroll volute disposed between an exhaust gas inlet and the turbine wheel, and a bypass passage that permits communication between the exhaust gas inlet and an exhaust gas outlet and bypasses the turbine wheel. The turbine stage further includes a valve assembly disposed in the exhaust gas inlet. The valve assembly includes a first valve configured to control flow through a first port that communicates with one of the turbine volutes, and a second valve configured to control flow through a second port that communicates with the bypass passage. The valve assembly includes a valve shaft connected to both the first valve and the second valve, and the valve shaft is rotated by an actuator such that the first valve and the second valve can each be selectively moved between a closed position and an open position, and the time sequence order of opening of the first valve and the second valve is selectable. By this configuration, the first valve can open either before or after the second valve, and both valves are operated by a single actuator.

In one exemplary embodiment, the valve assembly is configured to permit the turbine stage to switch between single scroll operation and twin scroll operation while simultaneously providing wastegate functionality if desired. In particular, when the valve assembly is in a first valve configuration, one of the scrolls of the twin scroll volute is closed and the turbine section operates as a mono-scroll turbine. This allows exhaust gas flow to be routed through a single volute, allowing the turbine stage to function at half of its potential size, which reduces the time required to provide boost. This is advantageous during low engine speed (rpm), low engine load (BMEP) or reduced cylinder displacement for example due to deactivated cylinders, where there is relatively less exhaust gas flow. When the valve assembly is in a second valve configuration, exhaust gas flow is permitted to both scrolls of the twin scroll volute. Thus, the second volute is open at higher engine speeds to accommodate the increased exhaust gas flow rate associated with the higher engine speeds. When the valve assembly is in a third valve configuration, exhaust gas flow is permitted to both scrolls of the twin scroll volute, and a portion of the exhaust gas flow is diverted to the bypass passage, thereby preventing over speed rotation of the rotating assembly that includes the turbine wheel, the compressor wheel, and the connecting shaft.

In another exemplary embodiment, the valve assembly is configured to permit the turbine stage to switch between twin scroll operation, double scroll operation, and a wastegated twin scroll operation. In particular, when the valve assembly is in a first valve configuration, the first scroll of the twin scroll volute is prevented from communicating with the second scroll of the twin scroll volute, and the turbine section operates as a conventional twin scroll volute. In this configuration, the combustion cylinder's exhaust pulses are separated between the scrolls, providing higher turbine efficiencies at low engine speeds. When the valve assembly is in a second valve configuration, the first scroll of the twin scroll volute is permitted to communicate with the second scroll of the twin scroll volute, resulting in a mono-scroll operation. This is advantageous at high engine speeds during which large pulse pressures are generated in the turbine housing. Since the first scroll and second scroll are communicating, gas can flow between the two scrolls, permitting pressure relief within the scrolls. When the valve assembly is in a third valve configuration, the first scroll of the twin scroll volute is not permitted to communicate with the second scroll of the twin scroll volute, resulting in a dual-scroll operation. In addition, a portion of the exhaust gas flow from each scroll is diverted to the bypass passage, thereby preventing over speed rotation of the rotating assembly that includes the turbine wheel, the compressor wheel, and the connecting shaft.

In both exemplary embodiments, two valves are driven by a common rotating valve shaft, and are thus driven by a single actuator, which results in reduced manufacturing costs and a reduced overall size of the turbocharger.

Modes for carrying out the present invention are explained below by reference to an embodiment of the present invention shown in the attached drawings. The above-mentioned object, other objects, characteristics and advantages of the present invention will become apparent from the detailed description of the embodiment of the invention presented below in conjunction with the attached drawings.

DETAILED DESCRIPTION

Referring toFIGS. 1-3, an exhaust gas turbocharger1includes a compressor section10, a turbine section20, and a bearing housing8disposed between and connecting the compressor section10to the turbine section20. The turbine section20includes a turbine housing22that defines an exhaust gas inlet24, an exhaust gas outlet28, and twin scroll volute26disposed in the fluid path between the exhaust gas inlet24and exhaust gas outlet28. The twin scroll volute22includes a first turbine volute26aand a second turbine volute26bseparated from the first turbine volute via a wall34. A turbine wheel30is disposed in the turbine housing22between the first and second turbine volutes26a,26band the exhaust gas outlet28. The turbine section20includes a bypass passage56that connects the exhaust gas inlet24to the exhaust gas outlet28while bypassing the turbine wheel30, and a valve assembly40that is configured to control exhaust gas flow through the bypass passage56. In addition, the turbine housing22includes an annular connecting flange32used to join the turbine section20to the bearing housing8via bolts or a vee band (not shown).

A turbocharger shaft2is connected to the turbine wheel30, is rotatably supported within in the bearing housing8, and extends into the compressor section10. The compressor section10includes a compressor housing12that defines an air intake16, an air outlet18, and a compressor volute19. A compressor wheel14is disposed in the compressor housing12between the air intake16and the compressor volute19. The compressor wheel14is connected to, and driven by, the turbocharger shaft2.

In use, the turbine wheel30in the turbine housing22is rotatably driven by an inflow of exhaust gas supplied from the exhaust manifold of an engine. Since the turbocharger shaft2is rotatably supported in the bearing housing8and connects the turbine wheel30to the compressor wheel14in the compressor housing12, the rotation of the turbine wheel30causes rotation of the compressor wheel14. As the compressor wheel14rotates, it increases the air mass flow rate, airflow density and air pressure delivered to the engine's cylinders via an outflow from the compressor air outlet18, which is connected to the engine's intake manifold.

In the turbocharger1, the amount of exhaust gas delivered to the turbine wheel30is controlled via the valve assembly40to assure that the compressor section10produces the proper boost over the full range of engine operating speeds, as discussed further below. The valve assembly40is supported within a valve housing42that is disposed in the exhaust gas inlet24between an inlet flange25and the first and second turbine volutes26a,26b.

Referring toFIGS. 4-7, the valve assembly40includes a valve shaft44, a first valve60disposed on an end45aof the valve shaft44, and a second valve80disposed on the shaft44at a location slightly spaced apart from the first valve60. Each of the first and second valves60,80includes a valve body61,81that moves relative to a valve seat71,91to open and close the valve60,80. The first and second valves60,80are rotary valves. As used herein, the term rotary valve refers to a valve in which the valve shaft44is fixed directly to the valve body61,81, and extends in a direction normal to a valve seat-facing surface62,82of the valve body61,81. When the valve shaft44is rotated about its longitudinal axis46, the valve body61,81rotates about the shaft longitudinal axis46such that the valve body61,81remains parallel to, and rotatingly slides relative to, the valve seat71,91.

The first valve body61and the second valve body81are similar in that each is a rigid, thin, disc-shaped member having a circular profile (FIGS. 6 and 7). Each of the first and second valve bodies61,81include a central opening64,84which receives the valve shaft44and is fixed thereto. In particular, the first and second valve bodies61,81are connected to the valve shaft44via the respective central opening64,84, for example via a press fit, spline fit, or other conventional connection method. The first valve body61includes two valve openings65,66. The valve openings65,66of the first valve body61are disposed on opposed sides of the shaft44and have a fan shape (e.g., a truncated sector shape). The second valve body81includes a single valve opening85having a fan shape. When the first valve body61and the second valve body81are assembled with the shaft44, the second valve body valve opening85is longitudinally aligned with one of the first valve body valve openings (e.g., valve opening65).

The first valve seat71and the second valve seat91are similar in that each is a rigid, thin disc-shaped member having a circular profile (FIGS. 4 and 5) that is of slightly larger diameter than its respective valve body61,81. Each of the first and second valve seats71,91includes a central opening74,94which receives the valve shaft44therethrough and permits relative rotation between the shaft44and the respective valve seat71,91. In some embodiments, a bushing or bearing (not shown) may be disposed in the central opening74,94to enhance support of the valve shaft44. Each of the first and second valve seats71,91includes a single valve opening75,95having a fan shape. When the first valve seat71and the second valve seat91are assembled with the shaft44, the second valve seat valve opening95is longitudinally aligned with the first valve seat valve opening75.

The first valve body61is connected to the valve shaft44such that an outward-facing surface63near the valve shaft terminal end45a, and an inward-facing surface62lies flush against a facing surface72of the first valve seat71. Thus, the first valve body61is disposed between the first valve seat71and the valve shaft terminal end45a.

Likewise, the second valve body81is connected to the valve shaft44such that an outward-facing surface83faces, and is spaced apart from, the first valve seat71, and an inward-facing surface82lies flush against a facing surface92of the second valve seat91. Thus, the second valve body81is disposed between the second valve seat91and the first valve seat71.

Referring toFIGS. 8 and 9, in the illustrated embodiment, the exhaust gas inlet24includes an inlet flange25having a single inlet opening27(FIG. 8). At the inlet opening27, a primary passage portion24aof the exhaust gas inlet24defines a single, relatively large inlet passageway. At a location corresponding to the valve housing first end47, the primary passage portion24abifurcates into two, somewhat smaller secondary passage portions24b,24cwhich are separated by an extension of the wall34that divides the turbine volutes26a,26b. A first secondary passage portion24bprovides communication between the primary passage portion24aincluding the inlet opening27and the first turbine volute26a, and a second secondary passage portion24cprovides communication between the primary passage portion24aincluding the inlet opening27and the second turbine volute26b. The valve assembly40is supported relative to the exhaust gas inlet24via the valve housing42. The valve housing42has a generally cylindrical sidewall43that extends between the closed valve housing first end47that intersects and is integral with the exhaust gas inlet24, and an open valve housing second end48that is opposed to the valve housing first end47. The valve housing42is disposed on the exhaust gas inlet24at an angle such that a longitudinal centerline39of the valve housing42is at an acute angle relative to an axis defined by a direction of gas flow through the primary passage portion24a.

The valve housing42includes three ports50,52,54(FIG. 9). The first port50is disposed in the valve housing first end47and permits communication between the valve housing42and the exhaust gas inlet24. The first port50opens to the primary passage portion24aof the exhaust gas inlet24in the vicinity of the passage bifurcation. The second port52is disposed in the valve housing sidewall43adjacent the valve housing first end47, and permits communication between the valve housing42and the second secondary passage portion24c, and thus also the second turbine volute26b. The third port54is disposed in the valve housing sidewall43adjacent the valve housing second end48, and permits communication between the valve housing42and the bypass passage56that extends between the valve housing42and the exhaust gas outlet28.

The valve assembly40is disposed with the valve housing42such that the valve shaft longitudinal axis46and the valve housing longitudinal centerline39are generally co-axial. In addition, the first valve60is disposed in the valve housing first end47so as to be positioned between the first port50and the second port52, and so as to control fluid flow through the first port50. To this end, the first valve seat71is secured to a first circumferentially-extending valve housing shoulder57for example via press-fit or welding so as to form a seal with the valve housing42. The first valve seat71is oriented such that the valve seat valve opening75overlies and is aligned with the first port50.

In addition, the valve assembly40is disposed with the valve housing42such that the second valve80resides between the second port52, which communicates with the second volute26b, and the third port54, which communicates with the bypass passage56. To this end, the second valve seat91is secured to a second circumferentially-extending valve housing shoulder55for example via press fit or welding so as to form a seal with the valve housing42.

In order to permit connection to the externally-located actuator, the valve shaft44extends out of the valve housing42through the open valve housing second end48. A cover41is welded into the open second end48so as to form a seal therewith, and the valve shaft44is rotatably supported within the cover41via an elongated bushing49. The cover41is supported on the valve shaft44at a location that is spaced apart from the second valve80. In addition, the cover41is located between the second valve80and an end45bof the valve shaft44that is configured to be connected to the actuator. The cover41and the bushing49permit the valve shaft44to rotate in a sealed manner relative to the valve housing42.

The first and second valves60,80segregate the valve housing42into a first chamber (e.g., a connecting chamber)58and a second chamber (e.g., a wastegate chamber)59. The connecting chamber58is defined between the first valve60and the second valve80, and includes the second port52that communicates with the second volute26b. Thus, depending on the position of the first valve60, the connecting chamber58serves to connect the exhaust gas inlet24to the second turbine volute26b. The wastegate chamber59is defined between the second valve80and the cover41, and includes the third port54that communicates with the bypass passage56. Thus, depending on the position of the first valve60and the second valve80, the wastegate chamber59serves to connect exhaust gas inlet24to the exhaust gas outlet28via the bypass passage56while bypassing the turbine wheel30.

Referring toFIGS. 10-13, during operation of the valve assembly40, the valve shaft44is actuated by the actuator to rotate about its longitudinal axis46. The open and/or closed state of the first and second valves60,80depends on the rotational position of the valve shaft44. For example, in some embodiments, the valve shaft44is rotated between three rotational positions: 0 degrees; 90 degrees; and 270 degrees. When the valve shaft44is in an initial rotational position (e.g., at a zero degree rotation), the first valve60and the second valve80are each oriented such that the valve openings65,66of the first valve body61are not aligned with the first valve seat valve opening75whereby the first valve60is closed, and the second valve body valve opening85is not aligned with the second valve seat valve opening95whereby the second valve80is closed. In this configuration, all exhaust gas flow through the turbine housing22is directed through the first secondary passage portion24bto the first turbine volute26a(FIG. 11). This valve shaft angular position would be appropriate for use during low exhaust gas flow such as occurs during low engine speed (rpm), low engine load (BMEP) or reduced cylinder displacement for example due to deactivated cylinders.

When the valve shaft44is moved by the actuator to the second rotational position (e.g., corresponding to a 90 degree rotation from the zero degree orientation), the first valve60and the second valve80are oriented such that the second valve opening66of first valve body61is aligned with the first valve seat valve opening75whereby the first valve60is open, and the second valve body valve opening85is not aligned with the second valve seat valve opening95whereby the second valve80is closed. In this configuration, a portion of the exhaust gas flow through the turbine housing22is directed is directed through the first secondary passage portion24bto the first turbine volute26a, and another portion of the exhaust gas flow through the turbine housing is directed into the second secondary passage portion24cto the second turbine volute26bvia the connecting chamber58(FIG. 12). This valve shaft angular position would be appropriate for use during moderate exhaust gas flow, and the flow to the second turbine volute26bcan be modulated by adjustment of the valve shaft rotational position.

When the valve shaft44is moved by the actuator to the third rotational position (e.g., corresponding to a 270 degree rotation from the zero degree orientation), the first valve60and the second valve80are oriented such that the first valve opening65of the first valve body61is aligned with the first valve seat valve opening75whereby the first valve60is open, and the second valve body valve opening85is aligned with the second valve seat valve opening95whereby the second valve80is open. In this configuration, a portion of the exhaust gas flow through the turbine housing22is directed is directed through the first secondary passage portion24bto the first turbine volute26a, another portion of the exhaust gas flow through the turbine housing is directed into the second secondary passage portion24cto the second turbine volute26bvia the connecting chamber58, and yet another portion of the exhaust gas flow through the turbine housing22is directed into the bypass passage56via the wastegate chamber59(FIG. 13). This valve shaft angular position would be appropriate for use during high exhaust gas flow, and the flow to the second turbine volute26band bypass passage56can be modulated by adjustment of the valve shaft rotational position.

For descriptive purposes, three discrete positions of the valve bodies61,81relative to the valve seats71,91are described above in which the respective valves60,80are either fully closed or fully open. However, it is contemplated that a range of intermediate positions can be achieved in which the respective valves60,80are partially open to any desired degree so as to provide a precisely controlled amount of exhaust gas flow through the valves60,80.

By using the valve assembly40in the turbine section20, available volute size (measured as A/R) can be optimized for (for example, made proportional to) turbine stage exhaust gas flow. In the configuration described above, high exhaust gas flow is paired with larger volute sizes, and low exhaust gas flow is pair with smaller volute sizes by varying turbine volute size, which is achieved by strategic routing of turbine exhaust gas flow between two adjacent turbine volutes26a,26b.

Accordingly, one embodiment of the invention comprises a turbocharger (1) configured to be connected to an engine, the turbocharger (1) comprisinga turbine section (20) includinga turbine wheel (30);a turbine housing (22) that encloses the turbine wheel (30) and definesan exhaust gas inlet (24),an exhaust gas outlet (28),a first turbine volute (26a) disposed between the exhaust gas inlet (24) and the turbine wheel (30),a second turbine volute (26b) disposed between the exhaust gas inlet (24) and the turbine wheel (30), the first and second turbine volutes (26a,26b) separated by a dividing wall (34),
the exhaust gas inlet (24) includingan inlet flange (25) including a flange opening (27),a first passage (24a,24b) that extends between the flange opening (27) and the first turbine volute (26a),a second passage (24a,24c) that communicates with the second turbine volute (26b),a valve housing (42) disposed in the exhaust gas inlet (24) between the inlet flange (25) and the first and second turbine volutes (26a,26b), the valve housing (42) includinga connecting chamber (58) having a first connecting port (50) that communicates with flange opening and a second connecting port (52) that communicates with the second passage (24a,24c),a wastegate chamber (59) having a first wastegate port (85,95) that communicates with the connecting chamber (58) and a second wastegate port (54) that that communicates with exhaust gas outlet (28),a first valve (60) configured to control flow through the first connecting port (50);a second valve (80) configured to control flow through the first wastegate port (85,95);a valve shaft (44) including a rotational axis, the valve shaft (44) connected to both the first valve (60) and the second valve (80),wherein the valve shaft (44) is driven by an actuator to rotate about the rotational axis (46) such thatthe first valve (60) and the second valve (80) can each be selectively moved between a closed position and an open position, andthe time sequence order of opening of the first valve (60) and the second valve (80) is selectable.

Since the valve assembly controls three flow conditions (first secondary passage open, first and second secondary passages open, first and second secondary passages and wastegate open), it is of course possible to design the valve as a three position valve. For example, the arc of the valve openings in either the first valve seat or first valve body is extended to maintain a continuous opening when switching between the second and third positions. When the valve is in the 0° position, both valve openings are closed and all exhaust gas flows through the first secondary passage24b. When the valve is rotated 90° the first valve60is open and exhaust flows through the first and second secondary passages24b,24c. When the valve is in the 180° position, the first valve60remains open, but now the second valve80opens, so that exhaust flows through first and second secondary passages and also the wastegate.

Referring toFIGS. 14-15, another embodiment valve assembly140is used to control the amount of exhaust gas delivered to the turbine section20′ of the turbocharger1to assure that the compressor section10produces the proper boost over the full range of engine operating speeds, and permit switching of the turbine volute26between a mono-scroll design and a twin-scroll design, as discussed further below. The valve assembly140is disposed in a valve housing142disposed in the exhaust gas inlet24between the inlet flange25and the first and second turbine volutes26a,26b.

Referring toFIGS. 16-19, the valve assembly140includes a valve shaft144, a first valve160disposed adjacent to, and slightly spaced apart from, an end145aof the valve shaft144, and a second valve180disposed on the shaft144at a location spaced apart relative to the first valve160. Each of the first and second valves160,180includes a valve body161,181that moves relative to a valve seat171,191to open and close the valve160,180. The first and second valves160,180are rotary valves, and the first valve160is slightly larger in diameter than the second valve180.

The first valve body161and the second valve body181are similar in that each is a rigid, thin, disc-shaped member having a circular profile (FIGS. 18 and 19). Each of the first and second valve bodies161,181include a central opening164,184which receives the valve shaft144and is fixed thereto. In particular, the first and second valve bodies161,181are connected to the valve shaft144via the respective central opening164,184, for example via a press fit, spline fit, or other conventional connection method. The first valve body161includes two valve openings165,166. The valve openings165,166of the first valve body161are disposed on opposed sides of the shaft144and have a fan shape. The second valve body181includes two valve openings185,186. The valve openings185,186of the second valve body181are disposed on opposed sides of the shaft144and have a fan shape. When the first valve body161and the second valve body181are assembled with the shaft144, the valve openings185,186of the second valve body181are not longitudinally aligned with the valve openings165,166of the first valve body161, and instead are offset by 45 degrees.

The first valve seat171and the second valve seat191are similar in that each is a rigid, thin disc-shaped member having a circular profile (FIGS. 16 and 17) that is of slightly larger diameter than its respective valve body161,181. Each of the first and second valve seats171,191includes a central opening174,194which receives the valve shaft144therethrough and permits relative rotation between the shaft144and the respective valve seat171,191. In some embodiments, a bushing or bearing (not shown) may be disposed in the central opening174,194to enhance support of the valve shaft144. The first valve seat171includes two valve openings175,176. The valve openings175,176of the first valve seat171are disposed on opposed sides of the shaft144and have a fan shape. The second valve seat191includes two valve openings195,196. The valve openings195,196of the second valve body191are disposed on opposed sides of the shaft144and have a fan shape. The valve openings195,196of the second valve body191are slightly larger (e.g., have a circumferential dimension that is larger) than that of the valve openings175,176of the first valve seat171. When the first valve seat171and the second valve seat191are assembled with the shaft144, the first valve opening175of the first valve seat171and the first valve opening195of the second valve seat191are longitudinally aligned, and the second valve opening176of the first valve seat171and the second valve opening195of the second valve seat191are also longitudinally aligned.

The first valve body161is connected to the valve shaft44such that the first valve seat171is disposed between the valve body161and the shaft terminal end145a. Likewise, the second valve body181is connected to the valve shaft144such that an outward-facing surface183faces, and is spaced apart from, the first valve body161, and an inward-facing surface182adjoins a facing surface192of the second valve seat191. Thus, the second valve body181is disposed between the second valve seat191and the first valve160.

Referring also toFIGS. 14 and 20, in the illustrated embodiment, the exhaust gas inlet124includes the inlet flange125having two inlet openings127a,127b(FIG. 14). The exhaust gas inlet124is separated into two inlet passageways124a,124bby an extension of the wall34that divides the two turbine volutes26a,26b. The first inlet passage124aprovides communication between the first inlet opening127aand the first turbine volute26a, and the second inlet passage124bprovides communication between the second inlet opening127band the second turbine volute26b(FIG. 20). In some embodiments, the first turbine volute26ais connected to a first set of cylinders of the engine (not shown) via the first inlet passageway124a, and the second turbine volute26bis connected to a second set of cylinders of the engine via the second inlet passageway124b, where the second set of cylinders has no common cylinders with the first set of cylinders.

The valve assembly140is supported relative to the exhaust gas inlet24via the valve housing142. The valve housing142has a generally cylindrical sidewall143that extends between an open valve housing first end147, and an open valve housing second end148that is opposed to the valve housing first end147. The valve housing142is disposed on the exhaust gas inlet124such that a longitudinal centerline139of the valve housing142is generally transverse an axis defined by a direction of gas flow through the two inlet passageways124a,124b. In addition, the longitudinal centerline139passes through the divider wall34between, and without intersecting, the first and second inlet passages124a,124b. In addition, the valve housing first end147is disposed on one side of the exhaust gas inlet124, and the valve housing second end148is disposed on an opposed side of the exhaust gas inlet124.

In order to permit connection to the externally-located actuator, the valve shaft144extends out of the valve housing142through the open valve housing second end148. A cover141is welded into the open second end148so as to form a seal therewith, and the valve shaft144is rotatably supported within the cover141via an elongated bushing149. The cover141is supported on the valve shaft144at a location that is spaced apart from the second valve180, whereby a connecting chamber158is formed between the second valve180and the cover141. In addition, the cover141is located between the second valve180and an end145bof the valve shaft144that is configured to be connected to the actuator. The cover141and the bushing149permit the valve shaft144to rotate in a sealed manner relative to the valve housing142.

A second cover138is welded into the open valve housing first end147so to close the valve housing first end147and form a seal therewith. The terminal end145aof the valve shaft144is rotatably supported within a central depression (not shown) formed on an inner surface of the second cover138. The second cover138is spaced apart from the valve seat171of the first valve160, whereby a wastegate chamber159is formed in the valve housing142between the first valve160and the second cover138. The wastegate chamber159is disposed on a side of the exhaust gas inlet124opposed to the connecting chamber158.

Referring toFIGS. 21 and 22, the valve housing142includes five ports151,152,153,154and155. The first port151is disposed in the exhaust gas inlet124and permits communication between the connecting chamber158of the valve housing142and the first inlet passage124a(FIG. 21). The second port152is disposed in the exhaust gas inlet124and permits communication between the connecting chamber158and the second inlet passage124b(FIG. 22). The third port153is disposed in the exhaust gas inlet124and permits communication between the wastegate chamber159of the valve housing142and the first inlet passage124a(FIG. 22). The fourth port154is disposed in the exhaust gas inlet124and permits communication between the wastegate chamber159and the second inlet passage124b(FIG. 21). The fifth port155is disposed in the valve housing sidewall143between the second cover138and the first valve160, and permits communication between the wastegate chamber159and the exhaust gas outlet28via a bypass passage156that bypasses the turbine wheel30.

The valve assembly140is disposed with the valve housing142such that the valve shaft longitudinal axis146and the centerline139of the cylindrical valve housing142are generally co-axial. In addition, the first valve160is disposed in the wastegate chamber159so as to control fluid flow through the third and fourth ports153,154. To this end, the first valve seat171is secured to a first circumferentially-extending valve housing shoulder157for example via welding so as to form a seal with the valve housing142. The first valve seat171is oriented relative to the shoulder157so that the first valve opening175of the first valve seat171is longitudinally aligned with the third port153, and the second valve opening176of the first valve seat171is longitudinally aligned with the fourth port154.

In addition, the valve assembly140is disposed with the valve housing142such that the second valve180is disposed in the connecting chamber158so as to control fluid flow through the first and second ports151,152. To this end, the second valve seat191is secured to a second circumferentially-extending valve housing shoulder167for example via welding so as to form a seal with the valve housing142. The second valve seat191is oriented relative to the second shoulder167so that the first valve opening195of the second valve seat191is longitudinally aligned with the first port151, and the second valve opening196of the second valve seat191is longitudinally aligned with the second port152.

The connecting chamber158is defined between the second valve180, the sidewall143and the first cover141. Although the connecting chamber158is connected to the inlet passageways124a,124bvia the first and second ports151,152, the connecting chamber158is otherwise free of ports. Thus, depending on the position of the second valve180, the connecting chamber158serves to connect the first inlet passageway124ato the second inlet passageway124b.

The wastegate chamber159is defined between the first valve160, the sidewall143and the second cover138, and is connected to the inlet passageways124a,124bvia the third and fourth ports153,154. In addition, the wastegate chamber159includes the fifth port155that communicates with the bypass passage56. Thus, depending on the position of the first valve160, the wastegate chamber159serves to connect exhaust gas inlet24to the exhaust gas outlet28via the bypass passage56while bypassing the turbine wheel30.

Referring toFIGS. 23-26, during operation of the valve assembly140, the valve shaft144is actuated by the actuator to rotate about its longitudinal axis146. The open and/or closed state of the first and second valves160,180depends on the rotational position of the valve shaft144. For example, in some embodiments, the valve shaft144is rotated between three rotational positions: 0 degrees; 45 degrees; and 90 degrees. When the valve shaft44is in an initial rotational position (e.g., at a zero degree rotation), the first valve160and the second valve180are each oriented such that the valve openings165,166of the first valve body161are not aligned with the first valve seat valve openings175,176whereby the first valve160is closed, and the second valve body valve openings185,186are not aligned with the second valve seat valve openings195,196whereby the second valve180is closed. In this configuration, the turbocharger turbine section20operates in a dual scroll mode in which all exhaust gas flow through the turbine housing22is directed through the two inlet openings127a,127bto the two turbine volutes26a,26bvia the respective inlet passageways124a,124b(FIG. 24). This valve shaft angular position would be appropriate for use during low exhaust gas flow such as occurs during low engine speed (rpm), low engine load (BMEP) or reduced cylinder displacement for example due to deactivated cylinders. Operation as a twin scroll turbine is advantageous since twin scroll designs can separate the exhaust pulses of the engine cylinders, providing high turbine efficiencies at low engine speeds, and providing higher low-end engine torque.

When the valve shaft144is moved by the actuator to the second rotational position (e.g., corresponding to a relative 45 degree rotation from the zero degree orientation), the first valve160and the second valve180are oriented such that the valve openings165,166of the first valve body161are not aligned with the first valve seat valve openings175,176whereby the first valve160is closed, and the second valve body valve openings185,186are aligned with the second valve seat valve openings195,196whereby the second valve180is open. In this configuration, all exhaust gas flow through the turbine housing22is directed through the two inlet openings127a,127bto the two turbine volutes26a,26bvia the respective inlet passageways124a,124b. In addition, the first inlet passageway124acommunicates with the second inlet passageway124bvia the connecting chamber158, whereby the turbocharger turbine section20operates in a mono scroll mode (FIG. 25). This valve shaft angular position would be appropriate for use during moderately high exhaust gas flow. Although mono scroll turbines do not separate engine exhaust pulses at low engine speeds, mono scroll turbines advantageously provide lower exhaust back pressure at high engine speeds, and provide higher peak engine horsepower.

When the valve shaft144is moved by the actuator to the third rotational position (e.g., corresponding to a 90 degree rotation from the zero orientation), the first valve160and the second valve180are oriented such that the valve openings165,166of the first valve body161are aligned with the first valve seat valve openings175,176whereby the first valve160is open, and the second valve body valve openings185,186are not aligned with the second valve seat valve openings195,196whereby the second valve180is closed. In this configuration, all exhaust gas flow through the turbine housing22is directed through the two inlet openings127a,127bto the two turbine volutes26a,26bvia the respective inlet passageways124a,124b. In addition, the first inlet passageway124aand the second inlet passageway124bcommunicate with the wastegate chamber159, whereby the turbocharger turbine section20operates in a wastegated mode (FIG. 26). This valve shaft angular position would be appropriate for use during very high exhaust gas flow in order to prevent over speed of the rotor group (e.g., the turbine wheel30, the compressor wheel14and the connecting shaft2). The flow to the bypass passage156can be modulated by adjustment of the valve shaft rotational position.

For descriptive purposes, three discrete positions of the valve bodies161,181relative to the valve seats171,191are described above in which the respective valves160,180are either fully closed or fully open. However, it is contemplated that a range of intermediate positions can be achieved in which the respective valves160,180are partially open to any desired degree so as to provide a precisely controlled amount of exhaust gas flow through the valves160,180.

The valve assemblies40,140allow a single turbocharger turbine20,20′ to function both as a mono-scroll turbine and as a single-scroll turbine, whereby the turbocharger can operate efficiently at all engine speeds. Moreover, the valve assemblies40,140include two rotary valves that can be rotationally oriented to independently control the valve sequence. For example, depending on the configuration of the valve openings in the respective valve seats and valve bodies, the first valve (i.e., the wastegate valve160) can open either before or after the second valve (i.e, the connecting valve180). In addition, both valves160,180can be operated by a single actuator, and, due to the rotary style, with very little torque.

It is contemplated that by strategic selection of the number, size, shape and distribution of the valve openings65,66,75,84,85,95,165,166,175,176,185,186,195,196of the two valves60,160,80,180, exhaust gas flow through the turbine housing can be regulated in various combinations of mono, dual and/or wastegated exhaust gas flow modes, where the modes can be made to occur in sequence or in parallel, and in varying amounts depending on the requirements of the specific application.

In the illustrated embodiments, the valve assembly40,140is connected to, and actuated by, a single actuator. The actuator may be controlled by the boost pressure produced by the turbocharger, a turbocharger controller, or an engine computer which uses the actuator to move the shaft. The turbocharger controller or the engine computer can measure numerous engine operating parameters and calculate the boost required for engine conditions, and the valve assembly can be controlled to allow the turbocharger to provide the required boost. Control of the actuator by the boost pressure is less satisfactory because it does not allow several factors to be taken into consideration in controlling the valve assembly.

In the illustrated embodiments, the actuator is non reversible, and the valves60,80,160,180can be opened and then closed (or closed and then opened) through actuation in a single direction of rotation of the actuator shaft44,144. In addition, the actuator is not limited to being non-reversible. For example, in some embodiments, the actuator is capable of reversing rotational directions, whereby the time sequence order of opening the valves can be reversed.

In the illustrated embodiments, the valve assembly40,140includes two valves160,180actuated by a common actuation rod (e.g., the valve shaft)44,144. Both valves160,180are rotary valves. However, the valve assembly40,140is not limited to employing rotary valves. For example, in some embodiments, one of the valves may be a rotary valve, and the other valve may be a flap valve in which the valve shaft extends in a direction parallel to the flap valve body and is rigidly connected to the flap valve body by an arm that extends perpendicular to the valve shaft. When the valve shaft44,144is rotated, the flap valve body rotates about the shaft axis such that the flap valve body is lifted off the flap valve seat and is angled relative thereto.

The size and scroll proportions of the twin scroll volute26of the turbine section are determined based on the requirements of a specific application. In some embodiments, the first turbine volute26aand the second turbine volute26have a substantially similar A/R ratio. In other embodiments, the first turbine volute26ahas a greater A/R ratio than the second turbine volute26b.

Although the valve body61,81,161,181and the valve seat71,91,171,191are described herein as having a circular peripheral shape, the valve body61,81,161,181and the valve seat71,91,171,191are not limited to this peripheral shape. The shape of valve seat71,91,171,191will likely correspond to the shape of the valve housing42,142and the shape of the valve body61,81,161,181can be made to match, or alternatively can have a polygonal shape or irregularly curved shape.

Although the valve body openings65,66,85and valve seat openings75,95are described herein as having a fan shape (e.g., a truncated sector shape), they are not limited to this shape. In some embodiments, the openings are shaped to maximize control of fluid flow therethrough. In some embodiments, the openings have other regular curved shapes such as circular or triangular. In some embodiments, the openings have irregular curved shapes (e.g., bean shaped, truncated fan shaped, crescent shaped, etc. In some embodiments, the shape and/or size of the valve body openings is different than the shape and/or size of the valve seat openings.

Selected illustrative embodiments are described above in some detail. It should be understood that only structures considered necessary for clarifying the inventive concepts have been described herein. Other conventional structures, and those of ancillary and auxiliary components of the system, are assumed to be known and understood by those skilled in the art. Moreover, while a working example has been described above, the inventive concepts are not limited to the working examples described above, but various design alterations may be carried out without departing from the present invention as set forth in the claims.