Abstract:
A vapor purge system for an engine, includes a purge valve having a housing including an input port in communication with a purge canister and including an output port in communication with an intake system component defining a first bore portion receiving the output port with a first seal member disposed therebetween. The intake system component includes a second bore portion receiving a housing portion of the purge valve with a second seal member disposed therebetween. The first and second seal members are spaced such that when the housing is pulled away from the intake system component and the first seal member is out of engagement between the first bore and the output port, the second seal member can remain in engagement so that a diagnostic module can diagnose detachment of the purge valve from the intake system before any hydrocarbon vapor can be released into the atmosphere.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/181,462, filed Jun. 18, 2015. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to internal combustion engines and more particularly to systems and methods for diagnosing leaks downstream of the purge flow control orifice. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Internal combustion engines combust a mixture of air and fuel to generate torque. The fuel may be a combination of liquid fuel and vapor fuel. A fuel system supplies liquid fuel and vapor fuel to the engine. A fuel injector provides the engine with liquid fuel drawn from a fuel tank. A vapor purge system provides the engine with fuel vapor drawn from a vapor canister. 
     Liquid fuel is stored within the fuel tank. In some circumstances, the liquid fuel may vaporize and form fuel vapor. The vapor canister traps and stores the fuel vapor. The purge system includes a purge valve. Selective actuation of the purge valve allows the fuel vapor to be drawn into the intake manifold and purge the fuel vapor from the vapor canister. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In a feature, a diagnostic system for a vehicle is disclosed. A purge valve control module closes a purge valve that regulates fuel vapor flow from a fuel vapor canister to an intake system of an engine. After the closing of the purge valve, a pump control module turns on a pump that pumps fuel vapor toward the purge valve. After the purge valve is closed, a pressure module determines a pressure measured using a pressure sensor located between the pump and the purge valve. A diagnostic module selectively diagnoses any leaks downstream of the purge flow control orifice based on the pressure. 
     In further features, the purge valve includes: a housing having an input port for receiving output from the pump; an output port for engaging an input port of a component of the intake system and a first seal that sealingly engages the purge valve output port to the input port of the intake system, and a second seal that sealingly engages the housing and a bore in the component. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a functional block diagram of an example direct injection engine system; 
         FIG. 2  illustrates an example fuel system and control system; 
         FIG. 3  is an example illustration of a purge valve that is attached to a component of an air intake system; 
         FIG. 4  is an example illustration of the purge valve of  FIG. 3  detached from the component of the air intake system; and 
         FIG. 5  is a functional block diagram of an example portion of an engine control module. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     A fuel system includes a vapor canister that traps and stores fuel vapor. A purge valve is selectively opened to purge the fuel vapor from the vapor canister to an internal combustion engine. In some types of engines, such as naturally aspirated engines, vacuum within an intake manifold may be used to draw fuel vapor through the purge valve. Other types of engines, such as boosted engines, may have insufficient vacuum or boost to draw fuel vapor through the purge valve. A pump may be used to pump fuel vapor from the vapor canister to an intake system of engines having insufficient boost or vacuum. Some purge valves may be directly coupled to a component of an intake system of an engine. 
     A control module selectively closes a purge valve and activates a pump to determine whether the purge valve is detached from an intake system of an engine. Closing the purge valve prevents fuel vapor flow into the intake system. However, fuel vapor may exit the purge valve when the purge valve is detached from the intake system. The control module therefore determines whether the purge valve is detached based on whether a pressure measured at a location between the pump and the purge valve increases over time when the purge valve is closed and the pump is on. 
     Referring now to  FIG. 1 , a functional block diagram of an example engine system for a vehicle is presented. An engine  10  combusts an air/fuel mixture to produce drive torque for a vehicle. While the engine  10  will be discussed as a spark ignition direct injection (SIDI) engine, the engine  10  may include another type of engine. One or more electric motors and/or motor generator units (MGUs) may be provided with the engine  10 . 
     Air flows into the engine  10  via an intake system  12 . More specifically, air flows into an intake manifold  14  through a throttle valve  16 . The throttle valve  16  may vary airflow into the intake manifold  14 . For example only, the throttle valve  16  may include a butterfly valve having a rotatable blade. A throttle actuator module  18  (e.g., an electronic throttle controller or ETC) controls opening of the throttle valve  16  based on signals from an engine control module (ECM)  20 . In various implementations, the intake system  12  includes one or more boost devices, such as one or more superchargers and/or one or more turbochargers, that increase airflow into the intake manifold  14  and, therefore, the engine  10 . 
     Air from the intake manifold  14  is drawn into cylinders of the engine  10 . While the engine  10  may include more than one cylinder, only a single representative cylinder  22  is shown. Air from the intake manifold  14  is drawn into the cylinder  22  through one or more intake valves of the cylinder  22 , such as an intake valve  24 . One or more intake valves  24  may be provided with each cylinder  22 . 
     A fuel actuator module  26  controls fuel injectors of the engine  10 , such as fuel injector  28 , based on signals from the ECM  20 . A fuel injector  28  may be provided for each cylinder. The fuel injectors  28  inject fuel, such as gasoline, for combustion within the cylinders. The ECM  20  may control fuel injection to achieve a target air/fuel ratio, such as a stoichiometric air/fuel ratio. 
     The injected fuel mixes with air and creates an air/fuel mixture in the cylinder  22 . Based upon a signal from the ECM  20 , a spark actuator module  30  may energize a spark plug  32  in the cylinder  22 . A spark plug  32  may be provided for each cylinder. Some types of engines, such as diesel engines, do not include spark plugs. Spark generated by the spark plug  32  ignites the air/fuel mixture. Exhaust resulting from combustion is expelled from the cylinder  22  via one or more exhaust valves, such as exhaust valve  34 , to an exhaust system  36 . One or more exhaust valves may be provided for each cylinder. 
     Referring now to  FIG. 2 , a functional block diagram of an example fuel system  40  is presented. The fuel system  40  supplies fuel to the engine  10 . More specifically, the fuel system  40  supplies both liquid fuel and fuel vapor to the engine  10 . The fuel system  40  includes a fuel tank  42  that contains liquid fuel. Liquid fuel is drawn from the fuel tank  42  and supplied to the fuel injectors of the engine  10  by one or more fuel pumps (not shown). 
     Some conditions, such as refueling, heat, vibration, and/or radiation, may cause liquid fuel within the fuel tank  42  to vaporize. A vapor canister  44  traps and stores vaporized fuel (fuel vapor). The vapor canister  44  may include one or more substances that trap and store fuel vapor, such as a charcoal. 
     A purge valve  46  includes a valve member that is selectively opened and closed to enable and disable, respectively, fuel vapor flow to the engine  10 . An example illustration of the purge valve  46  is provided in  FIGS. 3 and 4 . Operation of the engine  10  may create a vacuum relative to ambient pressure within the intake manifold  14 . 
     In some instances, such as when one or more boost devices are increasing airflow into the engine  10 , pressure within the intake manifold  14  may be greater than or approximately equal to ambient pressure. A pump  48  may be implemented that pumps fuel vapor from the vapor canister  44  to the purge valve  46 . When the purge valve  46  is open, the pump  48  also pumps fuel vapor from the vapor canister  44  toward the engine  10 . 
     The ECM  20  controls the purge valve  46  and the pump  48  to control the flow of fuel vapor to the engine  10 . The ECM  20  may also control a switching valve  50 . When the switching valve  50  is in a vent position, the ECM  20  may selectively open the purge valve  46  and turn on the pump  48  to purge fuel vapor from the vapor canister  44  to the intake system  12 . 
     The ECM  20  may control the rate at which fuel vapor is purged from the vapor canister  44  (a purge rate) by controlling opening and closing of the purge valve  46 . For example only, the ECM  20  may control the purge rate, the purge valve  46  may include a solenoid valve, and the ECM  20  may control the purge rate by controlling duty cycle of a signal applied to the purge valve  46 . Ambient air flows into the vapor canister  44  as fuel vapor flows from the vapor canister  44  toward the intake system  12 . 
     A driver of the vehicle may add liquid fuel to the fuel tank  42  via a fuel inlet  52 . A fuel cap  54  seals the fuel inlet  52 . The fuel cap  54  and the fuel inlet  52  may be accessed via a fueling compartment  56 . A fuel door  58  may be implemented to shield and close the fueling compartment  56 . 
     The ambient air provided to the vapor canister  44  through the switching valve  50  may be drawn from the fueling compartment  56 . A filter  60  receives the ambient air and filters various particulate from the ambient air. 
     The switching valve  50  may be actuated to the vent position or to a pump position. The switching valve  50  is shown as being in the vent position in the example of  FIG. 2 . When the switching valve  50  is in the vent position, air can flow from the filter  60  to the vapor canister  44  via a first path  62  through the switching valve  50 . When the switching valve  50  is in the pump position, air can flow between a vacuum pump  64  and the vapor canister  44  via a second path  66  through the switching valve  50 . 
     When the vacuum pump  64  is on while the switching valve  50  is in the pump position, the vacuum pump  64  may draw gasses (e.g., air) through the switching valve  50  and expel the gasses through the filter  60 . The vacuum pump  64  may draw the gasses through the second path  66  and a reference orifice  70 . A relief valve (not shown) may be implemented to selectively discharge pressure or vacuum within the fuel system  40 . The vacuum pump  64  may be operated, for example, to determine whether one or more leaks are present in the fuel system. 
     The purge valve  46  is directly coupled to a component of the intake system  12 , such as the intake manifold  14  or an intake pipe through which air flows into the intake manifold  14 . In engines having a boost device, the purge valve  46  may be directly coupled to a component upstream of the boost device. 
       FIG. 3  includes an example illustration of the purge valve  46  including a housing  80  having an inlet port  82  and an outlet port  84 . The inlet port  82  is connected to a passage  86  ( FIG. 2 ) that is in communication with the pump  48 . The outlet port  84  can be connected to a component  90  ( FIGS. 3, 4 ) of the intake system  12 . 
     The purge valve  46  includes a valve member  92  that engages a valve seat  94  that selectively opens and closes off a first passage  96  extending through the housing  80 . The purge valve  46  includes a solenoid coil  98  that is provided with a control signal to actuate the valve to electro-magnetically move the valve member  92  to an open position against a biasing force of a spring  99 . 
     The housing  80  can include a mounting flange  100  with an aperture  102  for receiving a threaded fastener for securing the housing  80  to the component  90  of the intake system. The outlet port  84  includes an O-ring seal  104  that sealingly engages an inner surface of a first bore portion  106  of the component  90 . A second O-ring seal  108  is provided for sealingly engaging an outer surface of the housing  80  and an inner surface of a second bore portion  110  of the component  90 . The housing  80  further defines a second passage  112  (see  FIG. 4 ) in communication with the inlet opening  82  and a second end  114  of the housing  80 . 
     In the normal assembled condition of the purge valve  46  (shown in  FIG. 3 ), the first O-ring seal  104  is sealingly engaged between the outlet port  84  and the inner surface of the first bore portion  106 . In addition, the second O-ring seal  108  is sealingly engaged between the outer surface of the housing  80  and the inner surface of the second bore portion  110 . The second end  114  of the housing  80  also engages an end wall  116  of the second bore portion  110 . 
     When the purge valve  46  is assembled incorrectly or has pulled away from its proper mounting location, as shown in  FIG. 4 , the first O-ring seal  104  is disengaged from the first bore portion  106  while the second O-ring seal  108  remains in sealing engagement with the second bore portion  110  and the housing  80 . In this state, a communication path  112  is established between the inlet port  82  and the intake system  12  as shown by the dashed line  120 . 
     The valve member  92  regulates fuel vapor flow through the outlet port  84 . Fuel vapor output from the outlet  84  flows into the component  90  and into the air stream for combustion within the engine  10  when the purge valve  46  is attached to the component  90 . As the port valve seat  94  is blocked by the valve member  92 , fuel vapor flow through the outlet port  84  of the purge valve  46  is blocked when the purge valve  46  is attached to the component  90  of the intake system  12 . 
     The ECM  20  controls opening and closing of the valve member  92  to control the flow of fuel vapor into the component  90  of the intake system  12 . For example only, as described above, the ECM  20  may control a duty cycle of a signal applied to the valve member  92  to control the opening and closing of the valve member  92 . 
     A pressure sensor  130  ( FIG. 2 ) measures a pressure at a location between the pump  48  and the purge valve  46 . Based on the pressure measured using the pressure sensor  130 , the ECM  20  diagnoses whether the purge valve  46  is detached from the component  90  of the intake system  12 . When the purge valve  46  is detached from the component  90  of the intake system as illustrated by  FIG. 4 , fuel vapor can flow through the intake system  12  via flow path  120 . When the valve member  92  is closed and the pump  48  is on, a failure of the pressure measured by the pressure sensor  130  to increase may therefore indicate that the purge valve  46  is detached from the component  90  of the intake system  12 . 
     While the ECM  20  will be discussed as diagnosing detachment of the purge valve  46  from the component  90 , the diagnosis may be performed by another suitable module of a vehicle. 
       FIG. 5  is a functional block diagram of an example portion of the ECM  20 . A sampling module  204  receives the pressure signal  208  from the pressure sensor  130 . The sampling module  204  samples the pressure signal  208  and outputs pressure samples  212 . The sampling module  204  may also buffer, digitize, filter, and/or perform one or more other functions to produce the pressure samples  212 . 
     A purge valve control module  216  controls the purge valve  46 . A pump control module  220  controls the pump  48 . A triggering module  224  triggers performance of various functions for the diagnosis of whether the purge valve  46  is detached from the component  90  of the intake system  12 . 
     For example, the triggering module  224  generates a first trigger signal  228 . In response to the first trigger signal  228 , the purge valve control module  216  closes the purge valve  46  to fully closed. In this manner, fuel vapor flow through the outlet port  84  is blocked. 
     After generating the first trigger signal  228 , the triggering module  224  generates a second trigger signal  232 . The triggering module  224  may generate the second trigger signal  232 , for example, a first predetermined period after generating the first trigger signal  228 . In response to the second trigger signal  232 , the pump control module  220  turns the pump  48  on. 
     If the purge valve  46  is properly attached to the intake system  12 , the pressure measured by the pressure sensor  130  should increase. The pressure should increase because fuel vapor flow through the outlet port  84  is blocked (via the closed purge valve  46 ). However, if the purge valve  46  is detached from the intake system  12 , or if there is a break or other compromise at the outlet port between the valve and the O-ring, the pressure may not increase or may increase less than expected. This may be due to fuel vapor flowing through the second passage  120 . 
     After generating the first trigger signal  228 , the triggering module  224  generates a third trigger signal  236 . The triggering module  224  may generate the third trigger signal  236 , for example, a second predetermined period after generating the first trigger signal  228 . The triggering module  224  may generate the third trigger signal  236  before or after generating the second trigger signal  232  (i.e., before or after the pump  48  is turned on). In response to the generation of the third trigger signal  236 , a first pressure module  240  stores the pressure sample  212  and outputs the stored pressure sample as a first pressure  244 . 
     The triggering module  224  generates a fourth trigger signal  248  after generating the third trigger signal  236 . The triggering module  224  may generate the fourth trigger signal  248 , for example, a third predetermined period after generating the third trigger signal  236 . In response to the generation of the fourth trigger signal  248 , a second pressure module  252  stores the pressure sample  212  and outputs the stored pressure sample as a second pressure  256 . When the purge valve  46  is attached to the intake system  12 , the second pressure  256  should be greater than the first pressure  244  since flow through the purge valve  46  and into the intake system  12  is blocked. 
     A difference module  260  may be implemented to determine a pressure difference  264  between the second pressure  256  and the first pressure  244 . For example, the difference module  260  may set the pressure difference  264  based on or equal to the second pressure  256  minus the first pressure  244 . 
     A diagnostic module  268  determines whether the purge valve  46  is detached from the component  90  of the intake system  12 . Detachment of the purge valve  46  from the intake system  12  includes leaks between the purge valve  46  and the intake system  12  (e.g., one or more leaks in a valve seat between the purge valve  46  and the intake system  12 ). For example, the diagnostic module  268  may diagnose that the purge valve  46  is detached from the component  90  of the intake system  12  when the pressure difference  264  is less than a predetermined pressure. The predetermined pressure may be calibrated and is greater than zero. The diagnostic module  268  may diagnose that the purge valve  46  is attached to the component  90  of the intake system  12  when the pressure difference  264  is greater than the predetermined pressure. In various implementations, the diagnostic module  268  may determine whether the purge valve  46  is detached based on a comparison of the second pressure  256  with the first pressure  244 . 
     When the purge valve  46  is detached from the component  90  of the intake system  12 , the diagnostic module  268  stores a predetermined diagnostic trouble code (DTC)  272  in memory  276 . The predetermined DTC indicates that the purge valve  46  is detached from the component  90  of the intake system  12 . A monitoring module  278  monitors the memory  276  and illuminates a malfunction indicator lamp (MIL)  280  when the purge valve  46  is detached from the component  90  of the intake system  12 . 
     The MIL  280  may, for example, indicate that it may be appropriate to seek servicing for the vehicle. Upon servicing the vehicle, a vehicle service technician may access the memory  276 . The predetermined DTC may serve to indicate to the vehicle service technician that the purge valve  46  is detached from the intake system  12 . One or more other remedial actions may also be taken when the purge valve  46  is detached from the intake system  12 . As one example, the pump  48  may be disabled. Additionally, the purge valve  46  may be opened and the switching valve  50  may be actuated to the vent position to equalize the pressure across the vapor canister  44 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.