Abstract:
A new and improved EGR valve having a valve body having an inlet port and an outlet port with a valve member moveably supported within the valve body between the inlet and outlet ports. A control cap is connected to the valve body and contains an integrated sensor that is used to provide an engine control module with pressure readings from the valve body and the interior portion of the cap. Additionally the cap also has an integrated zero emissions system that is capable of preventing the release of harmful chemicals into the atmosphere.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/482,647, filed Jun. 25, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a high flow exhaust gas recirculation (EGR) module having a sensor integrated into the cover of the electronic system module (ESM).  
       BACKGROUND OF THE INVENTION  
       [0003]     Federal and State legislation require control of vehicle exhaust emissions. Oxides of Nitrogen (NOx) are among the exhaust gas emissions that must be controlled. Formation of undesirable NOx gas will occur when there is a high combustion temperature inside of the engine. In an effort to remove or reduce combustion temperatures and NOx emissions, exhaust gas recirculation (EGR) valve systems have been developed. EGR valves function by recirculating a portion of the exhaust gas back to the intake manifold where it will be combined with incoming outside air. The mixing of the exhaust gas and the outside air will displace oxygen in the air intake system. When the mixture is compressed and ignited in the cylinder, the result is a lower combustion temperature (due to the lower levels of oxygen) and a reduction in NOx.  
         [0004]     There is a need in the art for exhaust gas recirculation systems to reduce the number of components needed to effectively recirculate exhaust gas to the air/fuel mixture. Such systems reduce the complicated on-board plumbing of the type required for vacuum actuated EGR systems.  
         [0005]     A typical EGR valve configuration using vacuum control uses an electrically actuated vacuum regulator (EVR) and a differential pressure sensor, also known as a delta pressure sensor. In turn, signals to and from these components are controlled by an engine control module (ECM). The effective control and simultaneous coordination of the various EGR components present some difficult challenges. More specifically, it is important to precisely actuate the EGR valve so that NO x  ignitions may be optimally minimized. However, as the number of components employed in an EGR valve system increases so will the system response time. This makes it more difficult and costly to control the overall process. In related art, the EGR, EVR and delta pressure sensor are typically separate components mounted at various places on the engine and interconnected via flexible or hard conduits referred to as “on-board plumbing.” In systems presently employed in the related art, each component often requires its own mounting strategy and associated fasteners. The on-board plumbing must be routed so as not to clutter the engine. This object is not always met in EGR systems presently used in the field today it can be difficult and expensive to service. Further, and because of ever shrinking space available for the vehicle power plant, the effective use of space through efficient component packaging is a parameter which designers must constantly seek to improve.  
         [0006]     Thus, there is a need in the art of exhaust gas re-circulation systems which reduces the number of components needed to effectively re-circulate gas to the air/fuel mixture. Further, there is a need for such a system that reduces the complicated on-board plumbing of the type required for vacuum actuated EGR systems. There is also a need in the art for an exhaust gas re-circulation system that is easy and inexpensive to service in the field. Finally, there is a need in the art for an exhaust gas re-circulation system which has improved response time and accurate repeatability and is smaller than present systems employed in the related art.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention is directed to a new and improved EGR valve for use in an automobile emissions system. The valve includes a valve body having an inlet port and an outlet port with a valve member moveably supported within the valve body between the inlet and outlet ports. A diaphragm housing is operatively mounted to the valve body and defines a vacuum cavity that is in fluid communication with a second source of pressure. A diaphragm member is disposed between the vacuum cavity and the valve body. The diaphragm member is moveable in one direction in response to a negative pressure induced in the vacuum cavity, and in the opposite direction in response to a biasing force associated with the valve member to effectively move the valve member between the open and closed position.  
         [0008]     The diaphragm housing is contained by a control cap that is connected to the valve body. Inside of the control cap is a vacuum regulator that is operatively connected to the diaphragm housing. The vacuum regulator is operable to control the movement of the valve member between the open and closed positions by controlling the negative pressure induced in the vacuum cavity. The control cap also has a first conduit partially disposed through the cap, having one end of the first conduit operatively connected to the valve body near the inlet port. A second conduit is also partially disposed through the cap and has one end operatively connected to the vacuum cavity. A sensor is operably positioned with respect to the first and second conduits. The sensor has a first tower that is positioned inside of the first conduit and a second tower that is positioned inside of the second conduit. The first tower is configured to sense a first characteristic, such as pressure, inside of the first conduit. The first tower transmits a signal value that is indicative of the value of the first characteristic. The second tower is configured to sense a second characteristic, such as pressure, inside of the control cap and transmits a signal value that is indicative of the value of the second characteristic. Lastly a seal element is molded over the first and second towers so that the control cap encapsulates the first and second towers and protects from the external environment.  
         [0009]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0011]      FIG. 1  is a schematic view of an internal combustion engine having the improved exhaust gas recirculation system of the present invention;  
         [0012]      FIG. 2  is a perspective side view of the exhaust gas recirculation valve having a sensor integrated into the cover;  
         [0013]      FIG. 3  is a cross-sectional side view of the exhaust gas recirculation valve;  
         [0014]      FIG. 4  is an overhead plan view of the exhaust gas recirculation valve having a sensor integrated cover;  
         [0015]      FIG. 5  is an overhead cross-sectional plan view of the exhaust gas recirculation valve having a sensor integrated cover; and  
         [0016]      FIG. 6  is an exploded side perspective view of the sensor integrated cap;  
         [0017]      FIG. 7  is a bottom plan view of the exhaust gas recirculation valve having a sensor integrated cover.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0019]     An exhaust gas recirculation system  10  of the present invention is shown in  FIG. 1  in conjunction with a schematically illustrated internal combustion engine generally shown at  12 . Thus, the internal combustion engine  12  is shown in  FIG. 1  having one representative combustion chamber, generally indicated at  14 , formed in an engine block  16 . A piston  18  is supported for reciprocal motion within a cylinder  20 . Together, the piston  18  and cylinder  20  define the combustion chamber  14 . Reciprocal motion of the piston  18  in response to a combustion cycle in the cylinder  20  imparts rotary motion to a crankshaft  22  via the connecting rod  24  as is commonly known in the art.  
         [0020]     A head  26  is mounted to the engine block  16  and includes at least one intake port  28  and at least one exhaust port  30 . The intake port  28  is in fluid communication with an intake manifold, schematically represented at  32 . Combustion air is drawn into the manifold  32  past a throttle  34  mounted in a valve body  50  where it is mixed with partially atomized fuel vapor. The throttle  34  moves to adjust the opening of the valve body  50  to adjust the amount of air flowing into the intake manifold  32  in response to certain predetermined parameters such as engine load, vehicle acceleration, etc. to regulate the air/fuel mixture to an optimum ratio.  
         [0021]     In turn, the flow of the combustible air/fuel mixture into the cylinder  20  via the intake port  28  of the head  26  is controlled by one or more intake valves  38 . The intake valves  38  may be supported in the head  26  for reciprocating motion under the influence of a camshaft  40  to open and close fluid communication between the intake port  28  and the cylinder  20 , as is commonly known in the art.  
         [0022]     Similarly, an exhaust valve  42  may be supported in the head  26  for reciprocating motion under the influence of a cam shaft  44  to open and close fluid communication between the cylinder  20  and the exhaust port  30 . When the exhaust valve  42  is open, the products of combustion, including exhaust gases having partially combusted pollutants such as NO x  are communicated to an exhaust manifold  46  through the exhaust port  30  formed in the head  26 .  
         [0023]     Where it is desired that the amount of pollutants should be reduced, a portion of the exhaust gas may be drawn off from the exhaust manifold  46  or any other suitable location on the engine and communicated to EGR system  10 . Fluid communication of exhaust gases from its source (the combustion cylinder  20 ) to the EGR system  10  is schematically represented by a dotted line  48 . Thus, those having ordinary skill in the art will appreciate that any suitable means for achieving this type of fluid communication may be employed without departing from the scope of the invention.  
         [0024]     Referring now to  FIG. 1  in conjunction with  FIGS. 2-7  the EGR system  10  can be mounted at any convenient location on the engine  12  and is in fluid communication with both the intake manifold  32  and the exhaust manifold  46 .  
         [0025]     Referring to  FIGS. 2-3 , the EGR system  10  includes a valve body  50 , having an exhaust port  52  which is adapted for fluid communication with a source of exhaust gas. In the embodiment illustrated in  FIG. 1 , this fluid communication is effected with the exhaust manifold  46  via one or more conduits represented by the dotted line  48 . In addition, the valve body  50  is preferably a cast part that includes an intake port  54  which is adapted for fluid communication with the intake manifold  32  of the internal combustion engine  12 . In the embodiment illustrated in  FIG. 1 , the EGR system  10  is mounted directly to the intake manifold  32  and communicates therewith via a passage  56 . However, those having ordinary skill in the art will appreciate that the EGR system  10  may be mounted at any convenient place on the engine  12 .  
         [0026]     The EGR system  10  also includes a valve member  64 . The valve member  64  is movable between open and closed positions to control the flow of exhaust gas from the exhaust port  52  to the intake port  54  of the EGR system  10 . More specifically, the valve member  64  includes a valve element  66  and a valve stem  68  extending from the valve element  66  and through a bushing  70  in the valve body  50 . The valve element  66  is received on a valve seat  72  formed in the valve body  50  at the exhaust port  52  when the valve member  64  is in its closed position. The valve seat  72  includes a generally frustoconically shaped insert which defines a first, generally larger diameter portion  76  and a second generally smaller diameter portion  78  with a transition portion  80  extending therebetween. On the other hand, the valve element  66  includes an annular shoulder  74  adapted to sealingly engage the transition portion  80  of the valve seat  72  when the valve member  64  is in its closed position. The valve seat  72  and valve element  66  act to induce turbulent flow of the exhaust gases as they move past the valve seat  72  when the valve member  64  is moved to its open position. Turbulent flow of the exhaust gases is conducive to better mixing between the recirculated exhaust gas and the fresh intake air received into the intake manifold  32 .  
         [0027]     Above the bushing  70 , the valve stem  68  includes a nipple  76  formed at the distal end thereof. The purpose of the nipple is discussed in greater detail below. More specifically, the valve stem  68  defines a longitudinal axis A of the valve member  64 . Thus, in the embodiment disclosed herein, the exhaust gas recirculation system  10  employs a “pull to open” type valve arrangement.  
         [0028]     The exhaust gas recirculation system  10  further includes a diaphragm housing  82  that is operatively mounted to the valve body  50  and supported thereby. The diaphragm housing  82  defines a vacuum cavity  84  in fluid communication with a source of negative pressure such as exists in the intake manifold  32  under certain engine operating conditions. The diaphragm housing  82  also defines an atmosphere cavity  86  that is in fluid communication with a source of second pressure. In the preferred embodiment, the source of second pressure is the ambient atmospheric pressure. A flexible diaphragm member  88  is disposed between the vacuum cavity  84  and the atmosphere cavity  86  and is operatively connected to the valve member  64 . More specifically, the diaphragm member  88  is made of a steel reinforced neoprene or some other suitable flexible material. The valve member  64  is operatively connected to the diaphragm member  88  via a mechanical attachment at the nipple  76  located at the distal end of the valve stem  68 . The diaphragm member  88  is movable in one direction in response to a negative pressure induced in the vacuum cavity  84  and in an opposite direction in response to a biasing force to move the valve member  64  between its open and closed positions as will be described in greater detail below.  
         [0029]     The diaphragm housing  82  includes an upper housing member  90  and a lower housing member  92  with the diaphragm member  88  operatively supported therebetween so as to define the vacuum and atmosphere cavities,  84 ,  86  respectively. The lower housing member  92  is supported by the valve body  50 . A biasing member  94  is supported within the diaphragm housing  82  and between the upper housing member  90  and the diaphragm member  88 . The biasing member  94  serves to bias the valve member  64  toward its closed position. In the preferred embodiment illustrated in these figures, the biasing member is a coiled spring  94 . However, those having ordinary skill in the art will appreciate that any number of biasing mechanisms commonly known in the related art may be employed for the same purpose.  
         [0030]      FIG. 6  depicts an exploded side perspective view of a sensor integrated cap  132 . The cap  132  is configured to be connected to the valve body  50 . The cap  132  has a pocket  134  that is a recess molded into the surface of the cap  132 . A first conduit  136  has a first end  137  that terminates inside of the pocket  134 , and a second end that terminates at a nozzle  138  protruding from the external surface of the cap  132 . A second conduit  140  has a first end  142  that terminates inside of the pocket  134  and a second end that terminates at a nozzle  144  protruding from the external surface of the cap  132 . A first tower  146  (also called a first die well) is positioned in the first conduit  126  at the first end  137 . A second tower  148  (also called a second die well) is positioned in the second conduit at the first end  142 . The first and second towers  146 ,  148  are connected to a lead frame  150  to collectively form a sensor  151 . The lead frame  150  is connected to a connector  152  and functions to transmit signals from the first and second towers  146 ,  148  out of the cap  132  to the ECM (not shown).  
         [0031]     A seal element  153  is placed over the sensor  151  to encapsulate the sensor  151  in the pocket  134  of the cap  132 . This protects the sensor  151  from the external environment outside the cap  132 .  
         [0032]     The exhaust gas recirculation system  10  of the present invention also includes and integrated vacuum regulator  96  contained within the cap  132 . The integrated vacuum regulator  96  is operable to control the movement of the valve member  64  between its opened and closed positions by controlling the negative pressure induced in the vacuum cavity  84 . The vacuum regulator  96  has a solenoid assembly  100  that acts to control the negative pressure induced in the vacuum cavity  84  as will be described in greater detail below.  
         [0033]     The vacuum regulator housing  98  includes a pair of cup shaped end caps  102 , 104  and a solenoid frame  106  extending therebetween, the vacuum regulator housing  98  is in fluid communication with vacuum cavity  84 . The solenoid assembly  100  includes a solenoid coil  108  and a bobbin  110 . A ferromagnetic valve member  105  is movably supported within the vacuum regulator housing  98  between open and closed positions in response to an electromagnetic force generated by the solenoid coil  108  thereby controlling the pressure in the vacuum cavity  84 . The solenoid coil  108  is connected to a source of electrical current which is inputted into the cap  132  via the connector  152 . In addition, the solenoid assembly  100  includes a fixed, ferromagnetic pole piece, generally indicated at  112 , having a passage  114  extending therethrough. The ferromagnetic valve member  105  is disposed in spaced relationship relative to the pole piece  112  even when the valve member  105  is in its closed position. More specifically, and to this end, the solenoid assembly  100  includes a sleeve  116  that is located between the pole piece  112  and the coil bobbin  110 . The sleeve  116  presents an annular valve seat  118 . The solenoid valve member  105  is disposed in abutting relationship relative to the annular valve seat  118  when the valve member  105  is in its closed position. Furthermore, the annular valve seat  118  serves to space the solenoid valve member  105  from the pole piece  112 .  
         [0034]     The pole piece  112  includes a body  120  and a stepped portion  122  having a smaller diameter cross-sectional area than the body  120 . The sleeve  116  presents a first, larger diameter portion  124  and a second, smaller diameter portion  125  with a shoulder  126  defined therebetween. The stepped portion  122  of the body  120  of the pole piece  112  is received in cooperating relationship with the shoulder  126  of the sleeve  116  thereby mechanically fixing the pole piece  112  relative to the sleeve  116 .  
         [0035]     The solenoid assembly  100  also includes a biasing member  128  which biases the solenoid valve member  105  into engagement with the valve seat  118  thus making the valve member be in a normally open position when the solenoid valve member  105  is de-energized. In the preferred embodiment illustrated in these figures, the biasing member  128  is a coiled spring supported between one of the cup shaped end caps  104  of the vacuum regulator housing  98  and the solenoid valve member  105 . However, those having ordinary skill in the art will appreciate that any number of biasing mechanisms may be used to accomplish this purpose.  
         [0036]     The nozzle  138  of the first conduit  136  is connected to the inlet port  54  of the valve body  50  using a tube  154 . The tube  154  is used to transfer a first characteristic which in the present embodiment is the vacuum pressure at the inlet port  54  to the first tower  146  located in the first conduit  136 . The first tower  146  is configured to allow the sensor  151  to read the first characteristic. The second tower  148  extends partially into the second conduit  140  at a first end and has a second end that extends through the sensor  151  and terminates above the sensor  151 . The second tower  148  is configured to allow the sensor  151  to read the value of a second characteristic. In the present embodiment the second characteristic is the pressure inside of the cap  132 . Having the two ends of the second tower  148  located above and below the sensor  151  allows for a more accurate pressure reading. The second conduit  140  has a nozzle  144  that allows for pressure to exit the cap  132  and move onto a source (not shown). The sensor  151  compares the values of the first and second characteristics and generates a delta value. The delta value is transmitted using the lead frame  150  though the connector  152  and onto the ECM located externally from the cap  132 . In an alternate embodiment it is possible for the sensor  151  to transmit signal values indicating the value for each characteristic, thus eliminating the need to use a delta sensor  151 .  
         [0037]     The cap  132  also has a vacuum nozzle  145  connected to the external surface. The vacuum nozzle  145  serves to supply to the cap  132  a source of vacuum pressure. The vacuum pressure is supplied from components that are external to the EGR system  10 . The vacuum pressure supplied through the nozzle  145  is what the second tower  148  is sensing when it generates a value indicative of the second characteristic. The pressure inside of the cap  132  can be controlled by the vacuum regulator  96 . The vacuum nozzle  145  supplies a vacuum to the cap. When the ECM determines that the negative pressure inside of the cap  132  is too great, a signal is sent via the connector  152  to the vacuum regulator  96 . The signal causes the vacuum regulator  96  to energize the solenoid assembly  100  that causes the ferromagnetic valve member  105  to move away from the valve seat  118  (e.g. the open position). The movement of the valve member  105  to the open position allows atmospheric air pressure to enter the cap  132  via atmospheric vents  166 . When this occurs the vacuum pressure inside of the cap  132  will drop and cause the biasing member  94  to press against the diaphragm member  88  to move the valve member  64  against the valve seat  72  to close the valve member  64 . When the signal generated from the sensor  151  causes the ECM to send a control signal to close the vacuum regulator  96  the vacuum pressure inside of the cap  132  will increase and cause the diaphragm member  88  to be pulled upward against the opposing force of the biasing member  94 . When the diaphragm member  88  moves upward, the valve element  66  will move away from the valve seat  72  to open the valve member  64  to allow the passage of exhaust gas from the exhaust port  52  to the intake port  54 . In this situation the pressure in the atmospheric cavity  86  is greater than the pressure in the vacuum cavity  84 .  
         [0038]     The characteristics measured by the first and second towers  146 ,  148  can be any type of condition that can exist at the inlet port  54 . In a preferred embodiment of the invention the first characteristic is the pressure (e.g. amount of vacuum) being induced at the inlet port  54  by the intake manifold  32 . However, the first characteristic sensed by the first sensor  146  can be other characteristics NO x , CO 2 , O 2 , CO composition, air temperature, humidity, the pressure or absence of solid particles etc., all of which depend on the type of application the valve is being used. For example, the EGR system  10  could be used for non-EGR functions such as a fuel vapor canister purge valve, an oil pump or a fluid pump such as the type used in transmission or clutch systems.  
         [0039]     One of the problems with conventional EGR systems is that they can leak emissions from the valve body  50 . This occurs when the valve member  64  moves to the closed position and the amount of vacuum at the intake port  54  drops. Emissions containing NO x  gas will then leak from the valve body. In applications where it is necessary to have zero emissions the present invention can further include a zero emission filtration system  156 . Referring to  FIGS. 5-6 , the zero emission filtration system  156  will include a vent tube  158  extending from the valve body  50  located above the intake port  54  upward to a vent nozzle  160  which protrudes from the cap  132 . The vent nozzle  160  serves as an aperture that directs any potential leaking emissions from the valve body  50  to the interior of the cap  132 . Once emissions enter inside the cap  132  they will come in contact with a first filter  162 . After passing through the first filter  162  the emissions will pass through a second filter  164  before being released to the atmosphere via the atmospheric vents  166  molded on the surface of the cap  132 . The function of the first and second filters  162 , 164  is to filter out environmentally harmful compounds contained in the emission gas. The first filter  162  can be made out of open cell foam such as a 4-800 CHARCOAL Z SIF II FELT filter. The first filter  162  functions primarily to filter out any larger size particles that may be in the emissions gas. The second filter  164  is an activated carbon filter that functions to filter out the environmentally harmful compounds before they are released into the atmosphere through the atmospheric vents  166 .  
         [0040]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.