Reverse offset wastegate valve assembly for improved catalyst light-off performance

A turbocharger assembly may include a turbine wheel. A turbine housing may surround at least part of the turbine wheel. A wastegate port may be defined by the turbine housing and may provide a bypass around the turbine wheel. A valve plate may be movable between a first position closing the wastegate port and a number of additional positions opening the wastegate port. The valve plate may have a face that faces the wastegate port. A shaft may be connected to the valve plate and may rotate about an axis at a pivot point. The pivot point may be located on an opposite side of a line from the valve plate, wherein the line may extend from the face and in a plane within which the face exists when the wastegate port is closed by the valve plate.

TECHNICAL FIELD

The field to which the disclosure generally relates includes turbochargers for use with internal combustion engines and more particularly, includes wastegate valves for turbochargers.

BACKGROUND

Turbochargers may be employed with internal combustion engines to pre-charge combustion air.

SUMMARY OF ILLUSTRATIVE VARIATIONS

A number of variations may involve a turbocharger assembly that may include a turbine wheel. A turbine housing may surround at least part of the turbine wheel. A wastegate port may be defined by the turbine housing and may provide a bypass around the turbine wheel. A valve plate may be movable between a first position closing the wastegate port and a number of additional positions opening the wastegate port. The valve plate may have a face that faces the wastegate port. A shaft may be connected to the valve plate and may rotate about an axis at a pivot point. The pivot point may be located on an opposite side of a line from the valve plate, wherein the line may extend from the face and in a plane within which the face exists when the wastegate port is closed by the valve plate.

Additional illustrative variations may involve a turbocharger assembly that may include a turbine wheel. A bypass may be defined around the turbine wheel. A surface may extend around and encircle the bypass. A valve assembly may selectively close the bypass. The valve assembly may include a face that mates with the surface. A forward area may be defined on the surface side of the face when the bypass is closed. The forward area may extend outward in a plane defined by the face. The face may rotate around an axis that may define a pivot point. The pivot point may be located in the forward area.

DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS

Part of a turbocharger system10is illustrated inFIG. 1according to a number of variations. A turbine housing12may define an exhaust gas flow circuit for channeling the incoming exhaust gas14. The exhaust gas14may be directed through an inlet15and at a turbine wheel inside the turbine housing12to induce rotation thereof. Part of the turbine housing12is shown broken away to reveal the turbine wheel11. After being used to impart rotation to the turbine wheel11, the exhaust gas may then be routed out of the turbine housing12, through an outlet16which directs the outgoing exhaust gas17to an exhaust system that may be connected to the turbine housing12. The inlet15may be surrounded by a flange for connection to an incoming exhaust conduit. The turbine housing12may also define an alternate exhaust gas flow path from the inlet15to another outlet18, wherein the exhaust gas may bypass the turbine wheel11. Flow to the outlet18may be controlled at a wastegate port by a valve assembly19that may be located inside the turbine housing12. The waste gate port may allow for exhaust gas to bypass the turbine wheel11and instead to be delivered directly from the inlet15to the outlet18so that exhaust gas may flow downstream in the exhaust system. The wastegate port may be opened to limit exhaust gases going through the turbine thereby operating as a boost-controlling device. In a number of variations the outlets16,18may not be separated, but instead may be combined in one opening for exhaust gas leaving the turbine housing12, since both may lead to the same downstream exhaust conduit.

The turbocharger system10may also include a compressor housing20that may contain a compressor wheel that may be connected to the turbine wheel11by a shaft. The compressor housing20may be configured to collect air and gases from the compressor wheel and channel them through an outlet22and on to an engine intake system that may be connected to the outlet22. The compressor housing20may be mounted to the turbine housing12by a central housing24that may support the shaft that connects the turbine wheel to the compressor wheel.

An actuator26may be mounted near the compressor housing20, on a bracket28. The actuator26may be operated through any of a number of mechanisms such as pneumatic including vacuum, electric, or other power sources. The bracket28may be connected to the central housing24or to the compressor housing20. An arm30may extend from the actuator26toward the turbine housing12. The arm30may include a first segment32and a second segment34, with its length adjustable with a nut36to lock the length. The arm30may include an end opposite the actuator26, with an opening through which a pin may extend forming a joint48. The pin may be connected to a lever42, which may be connected to a rotatable shaft44. The shaft44may extend into the turbine housing12and may be connected to a valve plate46(shown inFIG. 2), of the valve assembly19. As a result, translation of the arm30by the actuator26may rotate the lever42through the joint48, thereby rotating the shaft44and the valve plate46to selectively open and close the wastegate port.

Vehicles with internal combustion engines, including those that employ turbochargers, may include an emissions system, which may be located downstream in the exhaust flow from the turbine housing12. For emissions systems that use catalytic reactions, rapid warming following a cold start may be desirable for performance reasons. During a normal cold start, the emissions system is at ambient temperature and the engine exhaust may provide warming to a temperature at which catalyst reactions can occur. This warming period may be referred to as a light-off period. According to a number of variations, the valve assembly19may be used to open the wastegate port during cold starts to decrease catalytic converter light-off time. Allowing exhaust gas to bypass the turbine wheel11avoids heat loss to the turbine wheel11and its surrounding structures including of the turbine housing12, maintaining a higher temperature in the exhaust gas stream17delivered downstream to the catalytic unit.

Referring toFIG. 2the valve assembly19area is illustrated according to a number of variations. A section52of the turbine housing12may extend to a terminal surface54. A view directed at the terminal surface54is shown inFIG. 3with the valve assembly19open, and illustrates that the section52may define an opening referred to as wastegate port56. The wastegate port56may be part of the exhaust gas bypass57around the turbine wheel11. The terminal surface54may be flat and may be annular shaped and may encircle the wastegate port56. In a number of variations the terminal surface54may include a countersunk portion (not illustrated), inside its rim for valve mating purposes, which may also be considered a terminal surface for mating. The valve assembly19may include the valve plate46, which may have a face55that may mate with the terminal surface54as shown inFIG. 2to close the wastegate port56. The valve plate46may include an extension60that may be carried by an arm62. The extension60and arm62may be configured to allow the valve plate46to pivot relative to the arm62for secure seating of the face55against the terminal surface54. The arm62may extend to the shaft44and may be connected therewith.

In a number of variations the shaft44may rotate about an axis64that may be described as extending through the center of the shaft44along its length and directly into the view ofFIG. 2. The axis64may extend perpendicular to the direction that the wastegate port56extends through the section52, which is the same direction as the centerline70of the wastegate port56. The axis64may be alternatively referred to as the pivot point of the valve plate46, and may be offset on an opposite side of the terminal surface54from the valve plate46. This pivot point and the axis64may be in a forward area53that may be defined on the surface54side of the face55when the bypass57is closed by the valve plate46. The forward area53may exist across a plane defined by the face55from the valve plate46, when closed. In describing this area a reference line74may be used and may exist in a plane defined by the mating surface54and face55, and which may extend beyond the section52perpendicular to the centerline70. The forward area53may be referred to as the area to the left of the reference line74and the mating elements54,55in the perspective ofFIG. 2. As viewed inFIG. 2, the rearward area51may be the area on the opposite side of the reference line74from the forward area53and may be defined as the area on the valve plate46side of the surface54. This may be referred to as the area to the right of the reference line74and the mating elements54,55in the perspective ofFIG. 2. The face55, along with the other moving parts of the valve assembly19, may rotate around the axis64that defines the pivot point. The axis64and the pivot point may be located in the forward area53. In a number of variations the axis64may be a distance68into the forward area from the reference line74to a reference line72that may extend from the axis64and parallel to the reference line74. The distance68may be greater than zero and in a number of variations may place the entire shaft44in the forward area53, and which may provide desirable motion of the valve plate46. In addition, the shaft44may be positioned near or adjacent the section52defining the wastegate port56. This positioning may result in a minimum force vector on the shaft44when closing the valve plate46into the exhaust gas stream exiting the wastegate port56, by minimizing the distance from the axis64to the point at which the centerline70crosses the face55. When the wastegate port56is closed, the terminal surface54and the mating part of the face55may be considered as effectively occupying the same structural space. The entire shaft44may be located forward of the face55and on an opposite side of the terminal surface54from the valve plate46, and in other words, across the reference line74from the terminal surface54and in the forward area53. Offsetting the pivot point in front of the face55is accomplished by the structural shape of the arm62which may be comprised of a number of segments76,81and79. The segment76may extend from the shaft44beginning at a position forward of the face side78of the valve plate46and in the forward area53, to a position rearward of the back side80of the valve plate46and in the rearward area51. Because of the location of the pivot point in the forward area53, the valve plate46may immediately begin moving downward in the perspective ofFIG. 2, when the wastegate port56is initially opened by rotation of the shaft44to the position ofFIG. 4. The arm62may also include a segment79that engages the extension60and supports the valve plate46. The segment79may be disposed at an obtuse angle relative to the segment76by means of the curved intermediate segment81. As viewed inFIG. 2the axis64and the pivot point may be located outside the flow path through the wastegate port56, and may be located at a distance75from the centerline70and outside the outermost perimeter of the valve plate46away from the centerline70, and outside the wall87shown inFIG. 4), of the section52, through which the flow path is defined.

In a number of variations, the location of the pivot point at the axis64results in advantageous movement of the valve plate46off the terminal surface54as the shaft rotates to open the wastegate port56as shown inFIG. 4. The edge of the valve plate46at a point83, that is the part of the valve plate46nearest the segment81of the arm62, moves out of the flow82of exhaust gas leaving the wastegate port (downward as illustrated inFIG. 4), and away from the surface54. As the shaft44is rotated further to open the wastegate port56, an increasing amount of the valve plate46moves out of the path of the flow82. A curtain area84may be the flow area opened by the valve plate46between the reference lines88and89, and may be the amount of area available for flow out of the wastegate port56. The oncoming flow82leaving the wastegate port56may be diverted around the valve plate46and may be contained by a conduit wall86, such as of the turbine housing12. The downstream flow may be substantially channeled to such as within the reference line85and the opposite the wall86. The flow area may immediately increase in size as the valve plate46lifts off the terminal surface54. The location of the pivot point of the shaft44forward of the face55may maximize the expansion rate of the unobstructed flow area as the wastegate is opened. Maximizing expansion may result in less flow obstruction by the valve plate46and may minimize light-off time of a downstream catalyst during cold starts. As the shaft44is further rotated the amount to which the flow82is obstructed by the valve plate46is further reduced as shown inFIG. 5. The valve plate46may completely move out of the curtain area84with minimal rotation of the shaft44(clockwise as viewed inFIG. 5). As shown, the obstructed area may be eliminated as flow is free within the reference line92extending from the inside of the bottom part of the wall87. Due to the opening action, the effect on flow vectors may be minimized and may lead to maximized direct impingement of exhaust gas flow on the catalyst face, which may further minimize catalyst light-off times. This may especially be the case in systems where the catalyst unit is closely or directly coupled with the turbine housing12.

Variation 1 may involve a turbocharger assembly that may include a turbine wheel. A turbine housing may surround at least part of the turbine wheel. A wastegate port may be defined by the turbine housing and may provide a bypass around the turbine wheel. A valve plate may be movable between a first position closing the wastegate port and a number of additional positions opening the wastegate port. The valve plate may have a face that faces the wastegate port. A shaft may be connected to the valve plate and may rotate about an axis at a pivot point. The pivot point may be located on an opposite side of a line from the valve plate, wherein the line may extend from the face and in a plane within which the face exists when the wastegate port is closed by the valve plate.

Variation 2 may include the turbocharger assembly according to variation 1 and may include an arm that may extend from the shaft to the valve plate.

Variation 3 may include the turbocharger assembly according to variation 2 wherein the valve plate may include an extension engaged with the arm.

Variation 4 may include the turbocharger assembly according to variation 3 wherein the arm may include a first segment that may extend from the shaft at a position forward of the face, to a position rearward of the face on a back side of the valve plate. The arm may include a second segment that may engage the extension and may support the valve plate.

Variation 5 may include the turbocharger assembly according to any of variations 1-4 wherein the pivot point may be located along a line that extends from a center point of the valve plate and that may be oriented forward of the face.

Variation 6 may include the turbocharger assembly according to any of variations 1-5 wherein the wastegate port may be defined in a section of the turbine housing that may have a terminal surface that is flat and annular in shape and through which the wastegate port may be defined. The valve plate may mate against the terminal surface when in the first position.

Variation 7 may include the turbocharger assembly according to any of variations 1-6 wherein the shaft, in its entirety, may be located forward of the face and on the opposite side of the line.

Variation 8 may include the turbocharger assembly according to any of variations 1-7 wherein a flow path may be defined through the wastegate port and wherein upon opening to the number of additional positions the valve plate may immediately begin moving out of the flow path.

Variation 9 may include the turbocharger assembly according to any of variations 1-8 wherein the pivot point may be located outside a flow path defined through the wastegate port.

Variation 10 may involve may involve a turbocharger assembly that may include a turbine wheel. A bypass may be defined around the turbine wheel. A surface may extend around and may encircle the bypass. A valve assembly may selectively close the bypass. The valve assembly may include a face that mates with the surface. A forward area may be defined on the surface side of the face when the bypass is closed. The forward area may extend outward in a plane defined by the face. The face may rotate around an axis that may define a pivot point. The pivot point may be located in the forward area.

Variation 11 may include the turbocharger assembly according to variation 10 and may include a turbine housing surrounding the turbine wheel and defining an inlet and an outlet. The outlet may be part of the bypass and may include a terminal surface with which the face may mate. The entire terminal surface may be located at the plane.

Variation 12 may include the turbocharger assembly according to variation 10 or 11 and may include a shaft that may rotate around the axis and to which the face may be connected. The entire shaft may be located in the forward area.

Variation 13 may include the turbocharger assembly according to variation 12 and may include a valve plate that may define the face. The valve plate may be connected with the shaft by an arm that may include a first segment that may extend from the forward area to a position on an opposite side of the face from the forward area. The arm may include a second segment that may engage and may support the valve plate.

Variation 14 may include the turbocharger assembly according to any of variations 10-13 wherein the pivot point may be located along a line that may extend from a center point of the face and that may be oriented in the forward area.

Variation 15 may include the turbocharger assembly according to any of variation 10-14 wherein an exhaust gas may flow in a flow path through the bypass and out of the wastegate port when the face is unseated from the surface. A part of the face may be moved out of the flow path whenever the face is unseated.

The above description of select variations within the scope of the invention is merely illustrative in nature and, thus, variations or variants thereof are not to be regarded as a departure from the spirit and scope of the invention.