Patent Application
20180238336
This application relates generally to turbochargers for internal combustion engines, and more particularly relates to recirculation valves used with the turbocharger compressor for allowing some portion of the already-compressed air from the compressor discharge to be recirculated back to the compressor inlet.
Using a recirculation valve (RCV) with a turbocharger compressor to recirculate a portion of the already-compressed air back to the compressor inlet is a generally known strategy for delaying the onset of surge of the compressor to a lower flow rate at a given pressure ratio, or to a higher pressure ratio at a given flow rate. One drawback of the RCV, however, is that it tends to be a source of aerodynamically induced noise.
An objective of the present invention is to at least partially alleviate the problem of RCV noise. A particular noise issue with RCVs is a “rush” noise that occurs when the engine is operating at relatively high RPM and the driver suddenly releases the accelerator pedal and the RCV opens. Air rushing from the compressor discharge pipe through the RCV produces a “rush” noise that is distinctly audible to the vehicle occupants. The present disclosure describes a compressor recirculation valve having features for suppressing the “rush” noise.
In accordance with an embodiment of the invention, a recirculation valve for a turbocharger compressor comprises:
In accordance with an embodiment of the invention, the generally annular wall is disposed such that when the valve member begins to move from the closed position to the open position, the compressed recirculation air first flows radially outwardly following the valve seat, and then is turned by the generally annular wall to flow generally axially and past the upper edge of the generally annular wall before reaching and flowing radially outwardly through the transverse flow passage.
In one embodiment, a radially inner surface of the generally annular wall is conical, having a cone half angle α, a diameter of said radially inner surface at the upper edge being larger than a diameter of said radially inner surface at the base. Advantageously, the angle α can be greater than 0° but not exceeding about 45°.
In one embodiment, said radially inner surface of the generally annular wall at its base is spaced radially outward of a radially outer surface of the valve member by an amount b, wherein b is between 3% and 20% of a radius of said radially outer surface of the valve member.
In another embodiment, a radially inner surface of the generally annular wall defines a plurality of generally annular teeth that are axially spaced apart along said axial direction, the teeth projecting radially inwardly toward the valve member. Each tooth defines a radially innermost surface, and in accordance with one embodiment the radially innermost surfaces of the teeth all lie on a conical surface having a cone half angle α, said conical surface increasing in diameter along said axial direction. The angle α can be greater than 0° but not exceeding about 45°.
In a particular embodiment, a groove is defined between each pair of axially adjacent teeth, the groove having a V-shape on an axial cross-section through the recirculation valve. Each groove can have a V-angle β that is between 20° and 50°.
In accordance with one embodiment, said radially innermost surface of the tooth closest to the valve seat is spaced radially outward of a radially outer surface of the valve member by an amount b, wherein b is between 3% and 20% of a radius of said radially outer surface of the valve member.
The valve housing can define a chamber for receiving compressed air to be recirculated, the chamber being connected to the axial flow passage. In one embodiment, the valve housing further defines a volute for the compressor.
Having described the present disclosure in general terms, reference will now be made to the accompanying drawing(s), which are not necessarily drawn to scale, and wherein:
The present disclosure will now be described in fuller detail with reference to the above-described drawings, which depict some but not all embodiments of the invention(s) to which the present disclosure pertains. These inventions may be embodied in various forms, including forms not expressly described herein, and should not be construed as limited to the particular exemplary embodiments described herein. In the following description, like numbers refer to like elements throughout.
The RCV 30 includes an axial flow passage 32 defined by the valve housing 20. The passage 32 extends along a direction defined by an axis A of the recirculation valve. The valve housing further defines a generally annular valve seat 34 encircling the axis, and an annular cavity 36 surrounding the axial flow passage 32, the annular cavity being in fluid communication with the axial flow passage.
The RCV includes a valve member 40 disposed in the axial flow passage 32. The valve member is linearly movable along the axis A between a closed position (
The construction of the housing for the valve actuator can take various forms in the practice of the invention. In the illustrated embodiment, a separate actuator housing H contains the actuator that actuates the valve member 30, and the actuator housing H is fastened to the valve housing 20 by fasteners F. Alternatively, the actuator housing and valve housing can be formed together integrally.
The RCV 30 includes features for suppressing the “rush” noise that is created when the RCV opens to allow compressed air to flow from the axial passage 32 through a space that forms between the end of the valve member 40 and the valve seat 34 when the valve member is actuated to move along the axis A, the air then traveling into the transverse flow passage 29 and back into the inlet 22 of the compressor. As previously noted, this rush of air past the end of the valve member creates a “rush” noise that is distinctly audible to occupants of the vehicle in which the turbocharger is installed. In accordance with the invention, the “rush” noise is mitigated by providing a generally annular wall W projecting from the valve seat 34 generally in the axial direction defined by the axis A along which the valve member 40 moves toward the open position. The generally annular wall surrounds the valve member 40. The generally annular wall has a height h in said axial direction, measured between a base of the generally annular wall and an upper edge of the generally annular wall, as best seen in
In one embodiment as illustrated, the generally annular wall W is disposed such that when the valve member 40 begins to move from the closed position (
In accordance with the illustrated embodiment of
In one embodiment, said radially inner surface 44 at the base is spaced radially outward of a radially outer surface 41 of the valve member by an amount b, wherein b is between 3% and 20% of a radius of said radially outer surface of the valve member.
A groove is defined between each pair of axially adjacent teeth, the groove having a V-shape on an axial cross-section through the recirculation valve. In one embodiment, the grooves have a V-angle β that is between 20° and 50°.
In accordance with one embodiment, the radially innermost surface of the tooth T1 closest to the valve seat 34 is spaced radially outward of the radially outer surface 41 of the valve member by an amount b, wherein b is between 3% and 20% of a radius of said radially outer surface 41 of the valve member. It is also advantageous for the radial depth of the grooves to be equal to b.
Persons skilled in the art, on the basis of the present disclosure, will recognize that modifications and other embodiments of the inventions described herein can be made without departing from the inventive concepts described herein. For example, in the illustrated embodiment, the valve housing defining the axial passage 32 and valve seat 34 is formed integrally with the compressor housing (i.e., a single housing member defines the compressor features such as the diffuser 24 and volute 26, and also defines the valve features such as the valve passage 32 and valve seat 34). Alternatively, however, the valve housing can be a separate component that does not define any of the compressor features.
Additionally, while the disclosed embodiments have been described with reference to certain geometric parameters such as cone half angles α, V-angles β, and radial spacing distances b, and exemplary quantitative values have been described for such parameters, the invention is not limited to any particular values for these parameters; rather, the cited values are examples only.
Specific terms used herein are employed for explanatory purposes rather than purposes of limitation. Accordingly, the inventions are not to be limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. Other variations that do not depart from the described inventive concept are also included within the scope of the appended claims.
