Abstract:
The air induction system ( 10 ) includes a supercharger ( 12 ) and a valve assembly. The valve assembly comprises a valve ( 14 ) and a valve control mechanism ( 16 ). The supercharger ( 12 ) receives air through a supply opening ( 18 ) and pressurizes it. The valve ( 14 ) is in communication with the supply opening ( 18 ) to control air supply thereto. The control mechanism ( 16 ) is coupled to the valve ( 14 ) and causes it to vary the air supply to the opening ( 18 ) in response to air pressure conditions downstream from the supercharger ( 12 ). In one embodiment, the control mechanism ( 16 ) varies the air supply responsive to air pressure in the intake in order to both throttle the supercharger ( 12 ) as well as substantially eliminate undesirable surge conditions therein. Alternately, the control mechanism ( 118 ) varies the air supply responsive to air pressure in the inlet ( 110 ) of a turbocharger ( 106 ) to provide supercharged air thereto at a substantially constant pressure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 10/065,165 filed Sep. 23, 2002, which is a continuation of application Ser. No. 09/681,945 filed Jun. 28, 2001, now U.S. Pat. No. 6,474,318, which claims the priority of Provisional Application Serial No. 60/301,264 filed Jun. 27, 2001, all of which are entitled AIR INDUCTION SYSTEM HAVING INLET VALVE and are hereby incorporated by reference herein. 
    
    
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates generally to air induction systems for providing increased airflow to the intake of an engine. More particularly, the present invention concerns a supercharger system having an inlet valve that varies the supply of air to the supercharger in response to air pressure conditions downstream from the supercharger. The downstream air pressure conditions can vary depending on the application and could include for example pressure conditions in the engine intake or pressure conditions in the inlet to a downstream turbocharger. 
     2. Discussion of Prior Art 
     Centrifugal superchargers that increase air flow to an engine (thereby increasing the power generated thereby) are known in the art and typically utilize a compressor powered by the engine&#39;s crankshaft to supply pressurized air, or “boost,” to the engine. Known prior art centrifugal superchargers, however, are problematic and have several limitations. For example, conventional centrifugal superchargers have a somewhat linear boost response curve, therefore, if optimal boost is provided at higher engine rpms, the boost provided at lower engine rpms is significantly less than optimal. Conversely, if the typical centrifugal supercharger is set up to provide optimal boost at lower engine rpms, it will provide more boost than the engine can handle at higher engine rpms. 
     Known centrifugal superchargers are also problematic in that they suffer from undesirable surge conditions that are counterproductive to the operation of both the supercharger and the engine. For example, when a downstream restriction occurs, such as the closing of the engine throttle, the large pressure loads created can destroy the internal parts of the supercharger. Some prior art superchargers utilize a bypass valve that dumps the load into a recirculating line during these surge conditions; however, this bypass valve solution is problematic in that an undesirable pressure spike still occurs and the resulting pressure fluctuations can cause the mass flow meter to feed too much fuel into the engine. 
     Turbochargers, similar to superchargers, increase air flow to an engine; however, turbochargers utilize a compressor powered by the exhaust output by the engine. Known turbochargers also suffer from low-end boost problems, similar to those described above. Some prior art turbochargers utilize a supercharger upstream from the turbocharger, and powered by the engine&#39;s crankshaft, to supplement its low-end boost. These supercharged turbochargers, however, are problematic and have several limitations. For example, known supercharged turbochargers have an undesirable variance in the pressure supplied to the inlet of the turbocharger. That is, they are only supercharged at lower engine rpms and not operable to be supercharged at higher engine rpms. This is particularly problematic in high altitude applications wherein turbochargers typically do not supply sufficient boost for the desired engine power output. For example, diesel powered trucks frequently use turbochargers to boost engine power and these trucks are commonly used to transport heavy loads through high altitude conditions wherein the boost provided by the turbocharger at higher engine rpms is insufficient to desirably power the engine. Additionally, high altitude conditions lower volumetric efficiency and increase exhaust emissions. 
     SUMMARY OF INVENTION 
     The present invention provides an improved air induction system that does not suffer from the problems and limitations of prior art systems set forth above. The inventive system provides an inlet valve that varies the supply of air to the supercharger in response to air pressure conditions downstream from the supercharger. The valve can be used to both throttle the supercharger as well as substantially eliminate undesirable surge conditions therein by selecting pressure conditions in the intake to the engine as the controlling downstream pressure conditions. The inventive system can also be used to provide supercharged air at a substantially constant pressure to a turbocharger by selecting pressure conditions in the inlet to the turbocharger as the controlling downstream pressure conditions. 
     A first aspect of the air induction system of the present invention concerns a system for inducing airflow into the intake of an internal combustion engine including and broadly includes a centrifugal supercharger presenting an air supply opening and a spaced pressurized air exhaust opening and being operable to pressurize air between the supply and exhaust openings, and a valve in communication with the supply opening to control air supply thereto. 
     A second aspect of the air induction system of the present invention concerns a valve assembly to be used in an air induction system that induces airflow into the intake of an internal combustion engine, wherein the induction system includes a compressor presenting an air supply opening and a spaced pressurized air exhaust opening communicating with the engine intake. The valve assembly broadly includes a valve fluidly connectable to the supply opening to control air supply thereto, and a valve control mechanism including an air pressure sensor adapted to sense air pressure downstream from the air exhaust opening. The valve control mechanism is operable to cause the valve to vary the air supply depending on the air pressure sensed. 
     Another aspect of the air induction system of the present invention concerns an air induction system in a powered vehicle including an engine. The induction system broadly includes a turbocharger operable to pressurize air and deliver it to the engine and including an inlet operable to receive air. The induction system further includes a supercharger in communication with the inlet and being operable to pressurize air and deliver it to the inlet, wherein the supercharger includes an air supply opening operable to receive air. In addition, the induction system includes a valve in communication with the supply opening and being operable to vary air supply thereto so that air pressure of the pressurized air delivered to the inlet remains substantially constant. 
     Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     Preferred embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein: 
     FIG. 1 is a plan view of an air induction system constructed in accordance with a preferred embodiment of the present invention and shown in combination with an internal combustion engine (illustrated in a fragmentary and partially schematic view); 
     FIG. 2 is an enlarged longitudinal vertical sectional view of the inlet valve assembly of the induction system illustrated in FIG. 1 with a portion of the control mechanism broken away and illustrating the valve in the open position; 
     FIG. 3 is an enlarged longitudinal vertical sectional view of the inlet valve assembly with a portion of the control mechanism broken away and illustrating the valve in the over-boost induced closed position; 
     FIG. 4 is an enlarged longitudinal vertical sectional view of the inlet valve assembly with a portion of the control mechanism broken away and illustrating the valve in the surge-induced closed position; 
     FIG. 5 is a side elevational view of an air induction system constructed in accordance with an alternative embodiment of the present invention and shown in combination with an internal combustion engine in a truck; and 
     FIG. 6 is an enlarged plan view of the system illustrated in FIG.  5  and shown in combination with the engine (illustrated in a fragmentary and partially schematic view). 
    
    
     DETAILED DESCRIPTION 
     Turning initially to FIG. 1, the air induction system  10  selected for illustration is shown in use with an internal combustion engine E of a vehicle such as a boat or automobile. Although the illustrated engine E has eight cylinders, the principles of the present invention are equally applicable to various other types of engines. It is noted, however, that the air induction system  10  is preferably driven directly by the engine E, for example, the system  10  is drivingly coupled to the crankshaft of the engine E by a belt drive. Moreover, the system  10  is connected to the engine intake, including an intake plenum box B and an intake manifold M, by a conduit C, such that pressurized air generated by the system  10  is directed to the intake. In addition, an intercooler I is preferably in air communication with the conduit C to cool the pressurized air prior to it entering the intake. The principles of the present invention are not limited to the illustrated applications, but rather the inventive system  10  may be utilized in any application in which a highly pressurized, controlled air stream is desired (e.g., various other types of reciprocating engines, etc.). The illustrated air induction system  10  broadly includes a supercharger  12  in communication with a valve assembly. The valve assembly includes a valve  14  and a valve control mechanism  16 . 
     The illustrated supercharger  12  receives air through an air supply opening  18 , pressurizes the air in a compressor, and discharges the pressurized air through an air exhaust opening  20 . The illustrated supercharger  12  is preferably a centrifugal supercharger including a rotatable impeller and a step-up drive mechanism drivingly coupling the impeller to the engine E. However, the supercharger could be variously configured utilizing any suitable alternative design. Representative superchargers are disclosed in the following filed applications for U.S. Letters Patents (assigned of record to the assignee of the present application): Ser. No. 09/669,018, entitled GEAR DRIVEN SUPERCHARGER HAVING NOISE REDUCING IMPELLER SHAFT; Ser. No. 09/668,223, entitled CENTRIFUGAL SUPERCHARGER HAVING LUBRICATING SLINGER; and Ser. No. 09/706,007, entitled VELOCITY VARIANCE REDUCING MULTIPLE BEARING ARRANGEMENT FOR IMPELLER SHAFT OF CENTRIFUGAL SUPERCHARGER, which are all hereby incorporated by reference herein as is necessary for a full and complete understanding of the present invention. Most preferably, one or more of the supercharger designs disclosed in the foregoing applications will be utilized, as it is believed that they provide a supercharger capable of withstanding the additional operational loads experienced when an inlet valve is incorporated into the induction system. In particular, these supercharger designs provide long-lasting, durable bearing arrangements and a device that is unlikely to catastrophically fail due to the necessary higher operational speeds. 
     Air is supplied to the supercharger  12  by an inlet comprising an air filter  22 , the valve  14 , and the air supply opening  18  (see FIG.  1 ). Air is discharged to the engine E through an outlet comprising the air exhaust opening  20 , the conduit C, the intercooler I, the intake box B, and the intake manifold M. Although not illustrated, the inlet may alternatively communicate with a forwardly open conduit (not shown) that extends toward the front of the powered vehicle, such that air flow to the supercharger  12  is facilitated when the vehicle is moving in a forward direction. The valve  14  is in air communication with the air supply opening  18  and positioned upstream therefrom. The valve  14  controls the air supply to the supply opening  18 , which in turn controls the supply of air discharged to the engine E. 
     In particular, the valve  14  includes a housing  24  and a valve body  26  (see FIG.  2 ). The housing  24  is generally cylindrically shaped and includes open ports  28 , 30  on each opposing end. The filter  22  adjoins one end of the housing  24  so that port  28  is in air communication with the filter  22 . The opposing end of the housing  24  adjoins the air supply opening  18  of the supercharger  12  so that port  30  is in air communication with the air supply opening  18 . For purposes that will subsequently be described, the housing  24  further includes a radially enlarged section  32  defining a diameter that is greater than the diameter of each of the ports  28 , 30 . In this manner, two pairs of shoulders  34 , 36  and  38 , 40  are formed on the inside surface of the housing  24 . A pair of shoulders is adjacent each of the corresponding ports  28 , 30 . The housing  24  also includes a centrally located axial shaft  42  fixed to the housing  24  by a pair of spokes  44 , 46 . It will be appreciated that each of the spokes  44 , 46  are configured so that any obstruction of air flow through the housing  24  caused thereby is minimal, although alternative spoke configurations could be utilized (e.g., horizontal spokes, multiple spokes adjacent each port, etc.). 
     The valve body  26  is slidably mounted on the shaft  42  within the section  32  of the housing  24 . The valve body  26  is generally disc shaped having central apertures corresponding to the circumference of the shaft  42  to provide sliding of the valve body  26  relative to the shaft  42 . The valve body  26  is generally concentric with the housing  24 . The valve body  26  defines a body cross-sectional area that is greater than the inner cross-sectional area of each of the ports  28 , 30  but less than the inner cross-sectional area of the section  32 . In this manner, the valve body  26  is shiftable linearly along the shaft  42  between an open position as illustrated in FIG. 2, wherein the valve body  26  is generally coplanar with the center bulge section  32  so that air supply to the supply opening  18  (designated by arrows in FIG. 2) is substantially unrestricted by the valve body  26 , and a closed position as illustrated in either of FIG. 3 or  4 , wherein the valve body  26  is adjacent either pair of shoulders  34 , 36  (FIG. 4) or  38 , 40  (FIG. 3) so that air supply to the supply opening  18  is substantially restricted relative to the valve body  26  being in the open position. It will be appreciated that as the valve body  26  moves toward a respective pair of shoulders  34 , 36  or  38 , 40 , the air supply to the supply opening  18  will become progressively more restricted. Although the illustrated valve  14  is not shown with the valve body  26  physically engaging the paired shoulders  34 , 36  or  38 , 40  (nor is it imperative to the present invention), it is possible in application that the shoulders  34 , 36  or  38 , 40  actually function as a valve seat and physically engage the valve body  26  so that the air supply to the supply opening  18  is virtually shut off. For purposes that will subsequently be described, the valve body  26  defines a generally sealed internal cavity. It will be appreciated that given the importance of the valve body  26  being able to freely slide relative to the shaft  42 , it may not be possible to completely seal the internal cavity relative to the central apertures. 
     The valve could utilize various alternative designs, configurations, constructions, materials, etc., so long as the valve is operable to control air supply to the supercharger. Any type of suitable flow-control valve could be used utilizing many different housing, body, and seat configurations, for example, a square shaped housing, a simple butterfly valve, etc. However, it is preferred that the selected valve be operable to regulate or control air flow rather than merely being a gate that is either fully open or fully closed. 
     The valve control mechanism  16  senses air pressure downstream from the supercharger  12 . The valve control mechanism causes the valve  14  to vary the air supply to the supply opening  18  depending upon the downstream pressure conditions sensed. In particular, the control mechanism  16  includes a flexible diaphragm  48 , an atmosphere reference aperture  50 , and an intake reference line  52 . The flexible diaphragm  48  is fixed at both ends within the internal cavity of the valve body  26 , generally at the center of the valve body  26 , so that the diaphragm  48  and the valve body  26  cooperate to define two pneumatically isolated, collapsible chambers  54 , 56 . The diaphragm  48  includes a center aperture to allow insertion of the shaft  42  during assembly, however, once assembled the diaphragm  48  is fixed to the shaft  42  and sealed thereto by a sealing ring  58 . The chamber  54  communicates with the atmospheric pressure in the housing  24  by the atmosphere reference aperture  50  so that pressure within the chamber  54  is generally the same as the atmospheric pressure within the housing  24 . 
     The intake reference line  52  is connected at one end to the intake manifold M of the engine E with the other end venting into the chamber  56 . In particular, an inner-valve pathway  52   a  is formed through an upper portion of the axial center of the spoke  46  and through a portion of the axial center of the shaft  42  that extends between the spoke  46  and the chamber  56 . The pathway  52   a  extends radially through the shaft  42  so that the pathway  52   a  opens into the chamber  56  (see, e.g., FIG.  2 ). It will be appreciated that the pathway  52   a  could be formed in a number of different methods (e.g., drilling, molding during formation of the relevant parts, etc.). The inner-valve pathway  52   a  connects to an outer-valve pathway  52   b  to complete the reference line  52 . The outer-valve pathway is comprised of tubing threadably connected at one end to the exterior of the housing  24  and coupled to the intake manifold M at the other end. In this manner, air pressure in the intake manifold M is communicated through the reference line  52  to the chamber  56  so that pressure within the chamber  56  is generally the same as the pressure within the intake manifold M. 
     The valve control mechanism  16  causes the valve  14  to vary the air supply to the supply opening  18  depending upon air pressure in the intake manifold M (as communicated to the chamber  56  by the reference line  52 ) relative to a reference pressure. The reference pressure is the atmospheric pressure in the housing  24  as communicated to the chamber  54  by the aperture  50 . In particular, the control mechanism  16  causes the valve body  26  to shift out of the open position toward the closed position illustrated in FIG. 4 (i.e., toward the paired shoulders  34 , 36 ) thereby progressively restricting the air supply to the supply opening  18  when the downstream pressure condition is a surge condition. The surge condition occurs when the air pressure in the intake manifold M (and thus the air pressure in the chamber  56 ) is less than the reference atmospheric pressure in the housing  24  (and thus the air pressure in the chamber  54 ). The pressure differential caused by the surge condition collapses the chamber  56  while the chamber  54  simultaneously expands. Because the diaphragm  48  is fixed to the shaft  42 , the expansion of the chamber  54  causes the valve body  26  to shift toward the paired shoulders  34 , 36 . 
     The control mechanism  16  causes the valve body  26  to shift out of the open position toward the closed position illustrated in FIG. 3 (i.e., toward the paired shoulders  38 , 40 ) thereby progressively restricting the air supply to the supply opening  18  when the downstream pressure condition is an over-boost condition. The over-boost condition occurs when the air pressure in the intake manifold M (and thus the air pressure in the chamber  56 ) is greater than the reference atmospheric pressure in the housing  24  (and thus the air pressure in the chamber  54 ). The pressure differential caused by the over-boost condition expands the chamber  56  while the chamber  54  simultaneously collapses. Because the diaphragm  48  is fixed to the shaft  42 , the expansion of the chamber  56  causes the valve body  26  to shift toward the paired shoulders  38 , 40 . 
     The valve body  26  is yieldably biased into the open position by a pair of springs  60 , 62 . The springs  60 , 62  are slidably mounted on the shaft  42 , with each spring  60 , 62  being positioned in a respective one of the chambers  54 , 56 . The springs  60 , 62  freely float along the shaft  42 . In addition to biasing the valve body  26  into the open position, the springs  60 , 62  also cooperate with the pressure differential between the chambers  54 , 56  to determine when the valve  14  opens and closes. That is, the pressure differential in the chambers  54 , 56  must overcome the spring force in the corresponding spring  60 , 62  in order to collapse and expand the chambers and thereby shift the valve body  26  to a closed position. In this manner, the valve assembly can be tailored to a specific application by selecting a spring, or a pair of springs, having a particular spring force in order to set the conditions in which the valve opens and closes. 
     The valve control mechanism could utilize various alternative designs, configurations, constructions, etc., so long as the control mechanism is operable to cause the valve to vary the air supply to the supercharger. For example, the valve could be electronically or mechanically controlled. In addition, it is within the ambit of the present invention to utilize a valve control mechanism that does not automatically sense the valve-control conditions, for example, the valve could be remotely controlled by the vehicle operator selecting an open or close function depending on the operator&#39;s needs or desires. 
     In operation, air is drawn through the inlet into the supercharger  12  where it is pressurized and delivered to the engine E through the outlet. The step-up drive powers the supercharger  12  off of the engine E so that the supercharger  12  provides the desired boost at low-end engine speeds (e.g., 10 psi at 2500 rpm). As the engine speed increases, the valve control mechanism  16  causes the valve  14  to shift out of the open position thereby controlling the air supply to the supercharger  12  so that the supercharger  12  provides the desired boost without over-boosting at high-end engine speeds (e.g., 10 psi at 6000 rpm). Should a downstream restriction occur (e.g., the engine throttle closes), the valve control mechanism  16  causes the valve  14  to close thereby controlling the air supply to the supercharger  12  so that undesirable pressure spikes are prevented. 
     The inventive air induction system of the present invention could be configured for many different applications in which a controlled stream of pressurized air is desired. For example, the downstream pressure conditions that control the valve operation could be varied depending on the desired application. One such alternative embodiment is the air induction system  100  illustrated in FIGS. 5 and 6. Turning initially to FIG. 5, the air induction system  100  selected for illustration is shown in use with an internal combustion engine E of a truck T. Although the system  100  could be used in any internal combustion engine, it is most preferably a diesel engine (e.g., the type typically used by the over-the-road trucking industry, road working equipment, etc.). The air induction system  100  broadly includes a supercharger  102  in communication with a valve assembly  104 , located upstream from the supercharger  102 , and a turbocharger  106 , located downstream from the supercharger  102 . 
     The illustrated supercharger  102  is a centrifugal supercharger powered by the crankshaft of the engine E and is substantially similar to the supercharger  12  previously described, however, the air induction system  100  could utilize any suitable supercharger (e.g., Roots-type, screw-type, etc.). The illustrated supercharger  102  receives air through an air supply opening  108 , pressurizes the air, and outputs the pressurized air through an air exhaust opening. 
     The illustrated turbocharger  106  includes an inlet  110  for receiving pressurized air from the supercharger  102  through conduit  112 . Although not illustrated, an intercooler (not shown) could be included between the exhaust opening of the supercharger  102  and the inlet  110  of the turbocharger  106 . The turbocharger  106  further pressurizes the air received in inlet  110  and delivers it to the engine E through outlet  114 . The illustrated turbocharger  106  is a conventional turbocharger powered by the exhaust from the engine E and in this regard is in power communication with the exhaust manifold (not shown) of the engine E. The turbocharger could have many different configurations readily appreciated by those skilled in the art. 
     The valve assembly  104  is in communication with the air supply opening  108  of the supercharger  102  to vary air supply thereto. The valve assembly  104  is similar to the previously discussed valve assembly (illustrated in FIGS. 1-4) and includes a valve  116  and a valve control mechanism  118 . However, the valve control mechanism  118  is coupled between the valve  116  and the inlet  110  of the turbocharger  106  rather than the intake manifold of the engine E. In this manner, the valve control mechanism  118  senses pressure conditions in the inlet  110  of the turbocharger  106 . The valve control mechanism  118  causes the valve  116  to progressively restrict the air supply to the supply opening  108  of the supercharger  102  depending upon pressure conditions in the inlet  110  of the turbocharger  106  relative to the atmospheric pressure in the valve  116 . The valve  116  controls the air supply to the supply opening  108  of the supercharger  102  so that the air pressure in the inlet  110  of the turbocharger  106  remains substantially constant. 
     The inventive air induction system  100  compensates for changes in atmospheric pressure occasioned by changes in altitude (e.g., the inlet of the turbocharger receives pressurized air at a substantially constant pressure regardless of atmospheric pressure). In addition to stabilizing the boost in power output by the engine, it is believed using the inventive air induction system to supercharge a turbocharger also increases fuel efficiency and reduces emissions. Supercharging a turbocharger with the inventive system also provides the conventional advantage of providing boost to the turbocharger at low-end engine speeds. 
     The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.