Abstract:
A piston actuated diverter valve is employed to recirculate air through a turbocharger compressor when the device is not activated in an engine. An example diverter valve includes a housing forming a cylinder. A piston is arranged within the cylinder and an aperture passes from an exterior of the housing into the cylinder. A conduit is connected to the cylinder such that a pressurized fluid in the conduit acts to move the piston within the cylinder to cover and/or uncover the aperture.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/317,156, filed Mar. 24, 2010, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to turbochargers employed in internal combustion engines. 
       BACKGROUND 
       [0003]    Superchargers operate to increase the density of air entering an engine to increase the power output of the engine. Superchargers include compressors that may be employed for forced-induction of an internal combustion engine. Turbochargers are one type of supercharger in which the compressor is powered by a turbine, which, in turn, is driven by the exhaust gases of the engine, rather than with direct mechanical drive as with many other superchargers. Automobiles including some types of turbochargers, e.g. variable geometry turbochargers (VTGs), may employ a diaphragm boost recirculation valve, which is sometimes referred to as a diverter, anti-surge, bypass, blow-off valve (BOV) or dump valve. Turbocharger diverter valves circulate air through the system when the turbocharger is not in use, e.g. when the automobile engine is operating at speeds and engine frequencies (revolutions per minute, or, RPMs) that do not call for activation of the turbocharger. This prevents pressure build-up in the turbocharger when the throttle valve is closed. In this manner, the diverter valve acts as a pressure relief valve. The diverter valve also keeps the turbocharger spinning at high speeds. 
         [0004]    Originally such diverter valves are designed and fabricated to withstand the original equipment manufacturer&#39;s (OEM) specifications with respect to turbocharger boost pressure, airflow, and overall power output. However, when a turbocharged automobile undergoes certain aftermarket modifications, as is common with some classes of automobiles such as exotic sports cars, the OEM diaphragm diverter valve may begin to fail by seizing and/or leaking fluid from the pressurized turbocharger system. 
       SUMMARY 
       [0005]    In general, this disclosure is directed to piston actuated diverter valves that may be employed to recirculate air through a turbocharger compressor when the device is not activated in an engine. 
         [0006]    In one example, a turbocharger diverter valve includes a housing forming a cylinder. A piston is arranged within the cylinder and an aperture passes from an exterior of the housing into the cylinder. A conduit is connected to the cylinder such that a pressurized fluid in the conduit acts to move the piston within the cylinder to at least one of cover or uncover the aperture. 
         [0007]    In another example, a turbocharger includes a turbine and a compressor operatively connected to the turbine. A diverter valve is connected between an inlet and an outlet of the compressor. The turbocharger diverter valve includes a housing, a piston, an aperture, and a conduit. The housing forms a cylinder. The piston is arranged within the cylinder and the aperture passes from an exterior of the housing into the cylinder. The conduit is connected to the cylinder such that a pressurized fluid in the conduit acts to move the piston within the cylinder to at least one of cover or uncover the aperture. 
         [0008]    In another embodiment, an internal combustion engine includes a turbocharger comprising an intake manifold, a turbine, a compressor operatively connected to the turbine, and a diverter valve connected between an inlet and an outlet of the compressor. The turbocharger diverter valve includes a housing, a piston, an aperture, and a conduit. The housing forms a cylinder. The piston is arranged within the cylinder and the aperture passes from an exterior of the housing into the cylinder. The conduit is connected to the cylinder and to the intake manifold such that a fluid pressure within the intake manifold acts to move the piston within the cylinder to at least one of cover or uncover the aperture. 
         [0009]    The details of one or more examples of this disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of examples in accordance with this disclosure will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a schematic illustration of an internal combustion engine including a turbocharger. 
           [0011]      FIG. 2  is a schematic illustration of the turbocharger of  FIG. 1  including a diverter valve. 
           [0012]      FIG. 3  is a schematic illustration of the diverter valve of  FIG. 2 . 
           [0013]      FIG. 4  is a perspective view of an example diverter valve appropriate for use in turbochargers. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    The following examples include turbocharger piston actuated diverter valves that are employed to recirculate air through the turbocharger compressor when the device is not activated in an engine. The disclosed piston actuated diverter valves provide a robust design that facilitates use of the valves across a wide range of engine and turbocharger operating conditions. In particular, the disclosed example valves may operate effectively in a wider range of turbocharger boost pressures, airflows, and overall power output than prior designs. 
         [0015]      FIG. 1  is a schematic illustration of internal combustion engine  10  including engine block  12 , turbocharger  14 , and intercooler  16 . In  FIG. 1 , engine block  12  includes intake manifold  18  and intake valve  20 , exhaust manifold  20  and exhaust valve  22 , piston  24 , and cylinder  26 . Although only one cylinder  26  is shown in  FIG. 1  for illustrative purposes, engine  10  may and commonly will include multiple cylinders, e.g. four, six, or eight cylinders. Turbocharger  14  includes turbine  28 , compressor  30  and diverter valve  32 . In some examples, an internal combustion engine may include more than one intake and exhaust valve, e.g. two intake valves and two exhaust valves for each cylinder, which is sometimes referred to as a quattrovalve engine. The inlet of turbocharger  14  is connected to exhaust manifold  20  via conduit  34 . Similarly, the outlet of turbocharger  14  is connected to intercooler  16 , which is connected to intake manifold  18  of engine block  12 . Diverter valve  32  is connected to and actuated by pressure conditions in intake manifold  18  via conduit  35 . 
         [0016]    Generally speaking, during operation of engine  10 , turbine  28  of turbocharger  14  is driven by exhaust gas from cylinder  26 . Turbine  28  spins compressor  30 , which draws in and compresses ambient air to be transmitted through conduit  34  to intercooler  16 . The compressed air from turbocharger  14  is cooled in intercooler  16  before being transmitted to intake manifold  18 , in which it is mixed with fuel. The compressed air-fuel mixture enters cylinder  26  through intake valve  20  and is ignited in the cylinder by, e.g. a spark plug (not shown) to drive piston  24  down. The linear movement of piston  24  caused by ignition of the air-fuel mixture in cylinder  26  is translated into rotational movement, e.g. via a crank shaft, which is used to drive a vehicle that includes engine  10 , e.g. an automobile or an aircraft. Employing turbocharger  14  and intercooler  16  to compress and cool the intake air in engine  10  can provide significant performance gains over normally aspirated vehicles. 
         [0017]      FIG. 2  is a schematic illustration of turbocharger  14  including turbine  28 , compressor  30 , and diverter valve  32 . In some examples of the system of  FIG. 1 , engine  10  may include a mechanism that activates and deactivates turbocharger  14  at the appropriate operating conditions, e.g. particular speed and engine frequency (e.g. revolutions per minute, or, RPM) ranges. Engine  10  may, e.g., include throttle valve  40  that opens to activate turbocharger  14  by allowing compressed air from compressor  30  to be transmitted to intercooler  16  and onto intake manifold  18  and closes to deactivate use of the compressed air coming out of the turbocharger. When throttle valve is open  40  and turbocharger  14  is activated to provide compressed air to engine block  12 , diverter valve  32  is closed to allow ambient air that is drawn into and compressed by compressor  30  to flow into conduit  34  and onto intercooler  16 . However, as illustrated in  FIG. 2 , when throttle valve  40  of engine  10  is closed, diverter valve  32  opens to recirculate compressed air from outlet  42  of compressor  30  to the ambient air inlet of the compressor, thereby continually circulating air from inlet to outlet and back to the inlet until the throttle valve is opened again. Diverter valve  32  thereby prevents pressure build-up in the turbocharger when throttle valve  40  is closed and the compressed air produced by compressor  30  is effectively blocked. Additionally, because the compressed air blocked from flowing out of compressor  30  by throttle valve may flow back into the compressor and cause the turbocharger to slow or stop, diverter valve  32  may also act to keep the turbocharger spinning at high speeds even in interim periods during which the turbocharger is not activated. 
         [0018]      FIG. 3  is a schematic illustration of diverter valve  32  including housing  50  and piston  52 . Housing  50  includes first and second halves  54 ,  56 . First housing half  54  includes flange  58 . Similarly, second housing half  56  includes flange  60 . Generally speaking, flange  58  of first housing half  54  is connected to flange  60  of second housing half  56 . Connected first and second housing halves  54 ,  56  form cylinder  62 , in which piston  52  is arranged. Additionally, first housing half  56  includes nipple  64  and second housing half  56  includes port  66 . Conduit  35  is connected between nipple  66  an intake manifold  18  (not shown) of engine  10 . In some examples, conduit  35  may be releasably press fit over nipple  66 . 
         [0019]    Operation of diverter valve  32  is controlled by the pressure conditions in intake manifold  18  of engine  10  of  FIG. 1 . In particular, a net positive pressure in intake manifold  18  may act on piston  52  of diverter valve  32  via conduit  35  to drive the piston down and cover port  66 , thereby closing the diverter valve. The closed position of diverter valve  32  is represented in  FIG. 3  by piston  52  in dashed line in the down position. Positive pressure in intake manifold  18  may generally correspond to throttle valve  40  being open such that diverter valve  32  is closed to allow ambient air that is drawn into and compressed by compressor  30  to flow into conduit  34  and onto intercooler  16  when the throttle vale is open. Conversely, a net negative pressure in intake manifold  18  may act on piston  52  of diverter valve  32  via conduit  35  to retract the piston up and uncover port  66 , thereby opening the diverter valve. The open position of diverter valve  32  is represented in  FIG. 3  by piston  52  in solid line in the up or retracted position. Negative pressure in intake manifold  18  may generally correspond to throttle valve  40  being closed such that diverter valve  32  is open to recirculate compressed air from outlet  42  of compressor  30  to the ambient air inlet of the compressor, thereby continually circulating air from inlet to outlet and back to the inlet until the throttle valve is opened again. 
         [0020]    In some examples, opening and closing diverter valve  32  via piston  52  may be assisted by biasing piston  52  in either an open or closed position. For example, piston  52  may be biased down into the closed position for diverter valve  32 . In another example, piston  52  may be biased up into the open position for diverter valve  32 . In one example, piston  52  may be biased by a compression spring, e.g. helical coil spring  53  shown in  FIG. 3 . In another example, piston  52  may be biased by employing a canted coil spring that may exhibit a constant spring force over a relatively large range of displacements. 
         [0021]      FIG. 4  is a perspective view of example diverter valve  70  appropriate for use in turbochargers employed in internal combustion engines, e.g. turbocharger  14  of engine  10  of  FIG. 1 . Diverter valve  70  includes housing  72  and piston  74 . Housing  72  includes first and second halves  76 ,  78 . Although diverter valve  70  includes generally curvilinear, and, in particular cylindrical housing  72 , other examples may include alternatively configured housings. For example, a diverter valve according to this disclosure may include a rectilinear housing. First housing half  76  includes flange  80 . Similarly, second housing half  78  includes flange  82 . Generally speaking, flange  80  of first housing half  76  is connected to flange  82  of second housing half  78 . In the example of  FIG. 4 , flange  80  and flange  82  each include complementary tabs  84  and  86 , respectively. Tabs  84  and  86  each include apertures  88 , through which fasteners may be arranged to connect first and second housing halves  76 ,  78 , as well as, in some examples, to connect diverter valve  70  to another structure. In some examples, flanges  80  and  82  may include three or more tabs spaced approximately equidistant around a periphery of the flanges. Connected first and second housing halves  76 ,  78  form a cylinder (not shown), in which piston  74  is arranged. Additionally, first housing half  76  includes nipple  90  and second housing half  78  includes port  92 . 
         [0022]    The foregoing examples include turbocharger piston actuated diverter valves that provide a robust design to facilitate use across a wide range of engine and turbocharger operating conditions. The piston actuated diverter valves described may operate effectively in a wider range of turbocharger boost pressures, airflows, and overall power output than prior designs. As such, turbochargers employing such piston actuated valves may facilitate greater performance enhancements via increased boost pressures and airflows with a decreased risk of valve failure. 
         [0023]    Various examples have been described. These and other examples are within the scope of the following claims.