Patent Publication Number: US-11047344-B2

Title: Leakage diagnosis supplement method for failure of vacuum pump using active purge pump and leakage diagnosis supplement system for failure of vacuum pump using active purge pump

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0005074, filed on Jan. 15, 2019, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a leakage diagnosis supplement method for a failure of a vacuum pump using an active purge pump to determine whether or not a leakage in a fuel system occurs even when the vacuum pump with an evaporative leak check monitor (ELCM) module fails. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     A hybrid vehicle allows an engine to stop at an idle stop section in order to improve fuel efficiency. Thus, a fuel system leakage diagnosis method of an internal combustion vehicle, which determines whether or not a leakage occurs based on a pressure sensing signal of a pressure sensor mounted in the fuel tank at the idle state, is not able to be applied. 
     Accordingly, the hybrid vehicle diagnoses leakage in a fuel system using an evaporative leak check monitor (ELCM) module  1  at the engine stop state as shown in  FIGS. 1 to 3 . 
     As shown in  FIG. 1 , an atmospheric pressure is measured through a pressure sensor  3  in a state where a switching valve  2  is not operated, and then a vacuum pump  4  is operated so as to generate an air flow in the ELCM module  1 . A reference orifice  5  is mounted on the ELCM module  1  and the pressure sensor  3  is mounted on a rear end of the reference orifice  5  based on an air flow direction. A flow rate of an air flowing into the pressure sensor  3  by the reference orifice  5  becomes constant. Accordingly, a measurement value acquired by the pressure sensor  3  reaches an arbitrary value depending on various environment variables. This arbitrary value is measured as a first reference pressure value P 1 . 
     As shown in  FIG. 2 , a switching valve  2  is operated to generate an air flow in the fuel system including a canister and a fuel tank. The flow rate discharged from the fuel system to an atmosphere is gradually decreased. Accordingly, the measurement value acquired by pressure sensor  3  reaches an arbitrary value and then decreases nonlinearly and reaches a specific value depending on various environment variables, as shown in  FIG. 3 . At this time, the reached specific value is measured as a leakage determination value P 2 . 
     When the leakage determination value P 2  is measured, a purge control solenoid valve (PCSV) mounted on the purge line is opened. Since an outside air flows into the canister through the purge line, the measurement value continuously acquired by the pressure sensor  3  changes an appearance in a nonlinearly increasing manner, and thus the intensity of the signal is the same as that of the atmospheric pressure measured in advance. Failures of the PCSV and the vacuum pump  4  are diagnosed in a state where the PCSV is open, based on the nonlinear change in the measurement value acquired by the pressure sensor  3 . 
     When the measurement value acquired by the pressure sensor  3  is the same as that of the atmospheric pressure, the PCSV is closed and the switching valve  2  is changed to a non-operated state. Since the vacuum pump  4  is operated in a state where the switching valve  2  is not operated, the air flow is re-generated in the ELCM module  1 . Accordingly, the measurement value acquired by the pressure sensor  3  reaches an arbitrary value depending on various environment variables. This arbitrary value is measured as a second reference pressure value P 3 . 
     A state of the ELCM module  1  is determined and the leakage in the fuel system is determined based on the first reference pressure value P 1 , the leakage determination value P 2 , and the second reference pressure value P 3 . When the leakage determination value P 2  is less than the first reference pressure value P 1 , it is determined that the leakage does not occur. When the leakage determination value P 2  is more than the first reference pressure value P 1 , it is determined that the leakage occurs. 
     However, we have discovered that when the vacuum pump  4  mounted on the ELCM module  1  fails, the air flow may not be generated in the ELCM module  1 , the canister, or the fuel tank, and thus the fuel system leakage determination of the hybrid vehicle may not be performed. 
     SUMMARY 
     The present disclosure provides a leakage diagnosis supplement method for a failure of a vacuum pump using an active purge pump and a leakage diagnosis supplement system for a failure of the vacuum pump using the active purge pump which are capable of determining whether or not a leakage in a fuel system occurs even when the vacuum pump with an ELCM module fails. 
     In order to achieve the above-described object, according to an exemplary form of the present disclosure, a leakage diagnosis supplement method for a failure of a vacuum pump using an active purge pump includes: determining whether or not the vacuum pump mounted on a vent line between a canister and an atmosphere fails, reverse-rotating the active purge pump mounted on a purge line connecting the canister and an intake pipe to each other, determining whether or not an absolute value of internal pressure in a fuel tank is less than a specific value, and checking a leakage in a fuel system including the canister and the fuel tank. 
     In addition, when the absolute value of the internal pressure in the fuel tank is not less than the specific value, checking whether or not a leakage in the canister occurs may be performed. 
     In addition, when it is determined that the leakage in the fuel system occurs, checking whether or not the leakage in the canister occurs may be performed. 
     In addition, when it is determined that the leakage does not occur in the canister, it may be determined that a leakage in the fuel tank occurs. 
     In order to achieve the above-described object, according to one form of the present disclosure, there is provided a leakage diagnosis supplement system for a failure of a vacuum pump using an active purge pump, the system including a canister configured to absorb an evaporation gas from a fuel tank, a purge line configured to connect the canister and an intake pipe to each other, an active purge pump and PCSV configured to be mounted on the purge line, a vent line configured to connect the canister and an atmosphere, and a filter and an ELCM module configured to be mounted on the vent line. When the vacuum pump mounted on the ELCM module fails, the active purge pump reverse-rotates and diagnoses a leakage in the fuel tank or the canister based on a signal which is generated by a pressure sensor mounted on the ELCM module. 
     In addition, the ELCM module may include a switching valve switching connection between a plurality of flow paths which are provided inside of the ELCM module, air may be circulated in the ELCM module by a vacuum pressure which is generated in the vacuum pump when the switching valve is non-operated, and air in the canister and the fuel tank may be discharged to an atmosphere by the vacuum pressure which is generated in the vacuum pump when the switching valve is operated. 
     In addition, the active purge pump may reverse-rotate to move air from the canister toward the atmosphere when the vacuum pump mounted on the ELCM module fails. 
     In addition, the switching valve mounted on the ELCM module may be operated in a state where a value measured in the pressure sensor mounted on the ELCM module reaches a specific value which is less than the atmospheric pressure. 
     In such a configuration, according to a leakage diagnosis supplement method for a failure of a vacuum pump using an active purge pump and a leakage diagnosis supplement system for a failure of the vacuum pump using the active purge pump of one form of the present disclosure, even when the vacuum pump mounted on the ELCM module fails, air flow may be generated in the ELCM module, the canister, and the fuel tank by reverse-rotating the active purge pump, and thus it is possible to perform the fuel system leakage determination of the hybrid vehicle. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIGS. 1 and 2  are operating state diagrams showing an ELCM module in the related art; 
         FIG. 3  is a graph showing a signal generated in a pressure sensor mounted on the ELCM module in  FIGS. 1 and 2 ; 
         FIG. 4  is a flowchart showing a leakage diagnosis supplement method for a failure of a vacuum pump using an active purge pump according to one form of the present disclosure; 
         FIG. 5  is a view showing an example of a leakage diagnosis supplement system for a failure of the vacuum pump using the active purge pump according to one form of the present disclosure; 
         FIGS. 6 and 7  are operating state diagrams showing an ELCM module in the  FIG. 5 ; and 
         FIG. 8  is a graph showing a signal generated in a pressure sensor mounted on the ELCM module in  FIG. 5 . 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Hereinafter, a leakage diagnosis supplement method for a failure of a vacuum pump  750  using an active purge pump  300  and a leakage diagnosis supplement system for a failure of the vacuum pump  750  using the active purge pump  300  according to one form of the present disclosure will be described with reference to the accompanying drawings. 
     As shown in  FIG. 4 , the leakage diagnosis supplement method for a failure of the vacuum pump  750  using the active purge pump  300  according to one form of the present disclosure includes: a step S 100  of determining whether or not the vacuum pump  750  mounted on a vent line  500  between a canister  100  and an atmosphere fails, a step S 200  of reverse-rotating the active purge pump  300  mounted on a purge line  200  connecting the canister  100  and an intake pipe I to each other, a step S 300  of determining whether or not an absolute value of internal pressure in a fuel tank T is less than a specific value, and step S 400  of checking a leakage in the fuel system including the canister  100  and the fuel tank T. 
     In the step S 100  of determining whether or not the failure of the vacuum pump  750  occurs, the failure of the vacuum pump  750  based on the signal generated in the pressure sensor  772  may be determined. When the signal generated in the pressure sensor  772  does not change even if the vacuum pump  750  is operated, it is determined that the vacuum pump  750  fails. After the vacuum pump  750  is operated so as to have an interval, the failure of the vacuum pump  750  may be determined by comparing the signal or the change in the signal generated in the pressure sensor  772  when the vacuum pump  750  is operated. In the step S 100  of determining whether or not the failure of the vacuum pump  750  occurs, an atmosphere pressure is measured through the pressure sensor  772  mounted on an ELCM module  700 . 
     As shown in  FIG. 5 , a purge line  200  is mounted between the canister  100  and the intake pipe I. A purge control solenoid valve (PCSV)  400  is installed on the purge line  200 . The active purge pump  300  is mounted on the purge line  200  so as to be positioned between the PCSV  400  and the canister  100 . An air flows from the canister  100  toward the PCSV  400  when the active purge pump  300  normal rotates and the air flows from the canister  100  toward the vent line  500  when the active purge pump  300  reverse-rotates. 
     A pressure gauge (not shown) is installed between the canister  100  and the active purge pump  300 , and between the active purge pump  300  and PCSV  400 , respectively. The fuel tank T is connected to the canister  100  so as to adsorb an evaporated gas. The canister  100  is opened toward the atmosphere through the vent line  500 . A filter  600  and an ELCM module  700  are mounted on the vent line  500 . 
     When the evaporated gas collected in the canister  100  is purged, the active purge pump  300  normal rotates, a vacuum pressure is generated in the canister  100 , and the evaporated gas is compressed between the PCSV  400  and the active purge pump  300 . By compressing the evaporated gas between the PCSV  400  and the active purge pump  300 , a pressure of the evaporated gas may be equal to or greater than the atmospheric pressure. Accordingly, even when a turbo charger is installed on the intake pipe I, the evaporated gas may be injected to the intake pipe I. 
     Particularly, by adjusting a rotation speed of the active purge pump  300 , a timing of opening and closing the PCSV  400 , and an opening degree of the PCSV  400 , an amount of the evaporated gas flowing into the intake pipe I may be adjusted. In addition, as the evaporated gas flows into the intake pipe I, an amount of hydrocarbon to be additionally supplied into a combustion chamber may be adjusted. When a fuel injection quantity and the amount of hydrocarbon to be additionally supplied into the combustion chamber are adjusted in combination, combustion of the rich fuel may be prevented. It may be minimized the generation of contaminants caused by purging of the evaporated gas. 
     In the step S 200  of operating the active purge pump  300 , the PCSV  400  maintains a closed state. The active purge pump  300  reverse-rotates in an opposite direction which is different than when the evaporated gas is purged. The active purge pump  300  reverse-rotates from the canister  100  toward the vent line  500  so as to generate the air flow. As shown in  FIG. 6 , the air flow is generated in the ELCM module  700  by reverse-rotating the active purge pump  300 . By adjusting the rotation speed of the active purge pump  300 , a magnitude of a pressure generated in the canister  100 , the fuel tank T, the ELCM module  700 , and the vent line  500  may be adjusted. 
     The ELCM module  700  includes a switching valve  790  changing a connection between a plurality of flow paths which are provided in the ELCM module  700 . When the switching valve  790  is non-operated, an air is circulated in the ELCM module  700  by a vacuum pressure generated in the vacuum pump  750 . When the switching valve  790  is operated, the air in the canister  100  and the fuel tank T is discharged to the atmosphere by the vacuum pressure generated in the vacuum pump  750 . 
     As shown in  FIGS. 6 and 7 , the ELCM module  700  includes a first port  710  connected to the canister  100 ; a second port  720  connected to the filter  600  so as to open toward the atmosphere; a housing  730  having the first port  710  and the second port  720  formed on outside; a first flow path  740  formed inside the housing  730  so as to connect the first port  710  and the second port  720  to each other; the vacuum pump  750  mounted on the first flow path  740 ; a second flow path  760  connecting a first branch point D 1  and a second branch point D 2 , on the first flow path  740 , to each other; a reference orifice  771  and the pressure sensor  772  formed on the second flow path  760 ; a third flow path  780  connecting a third branch point D 3  and a fourth branch point D 4 , on the first flow path  740 , to each other; and the switching valve  790  mounted on the first flow path  740  and the third flow path  780  so as to disconnect the first flow path  740  and communicate the third branch point D 3  and the fourth branch point D 4  at the time of non-operating, and to disconnect the third flow path  780  and communicate the fourth branch point D 4  and the second branch point D 2  at the time of operating. 
     The air flowing into the first port  710  flows into the second flow path  760  through the first branch point D 1 . The air reaching the pressure sensor  772  passes through the reference orifice  771 , so that the flow rate remains constant. Since the flow rate of the air reaching the pressure sensor  772  is constant, the value obtained by converting the signal generated in the pressure sensor  772  into a figure reaches a constant value depending on various environment variables. The reaching value is measured as a first reference pressure value P 1 . 
     The air flows into the first flow path  740  through the second branch point D 2 , and then flows into the third flow path  780  through the third branch point D 3 . The air discharged from the first flow path  740  to the third flow path  780  flows into the first flow path  740  through the switching valve  790  and the fourth branch point D 4 , and is flowed into the second flow path  760  through the first branch point D 1  again. 
     Accordingly, in the step S 200  of reverse-rotating the active purge pump  300 , the air, which flows into the second flow path  760  by the reverse-rotating the active purge pump  300 , a rear end of the first flow path  740  with reference to the switching valve  790 , the third flow path  780 , and a front end of the first flow path  740  with reference to the switching valve  790 , flows in the ELCM module  700  repeatedly. 
     In the step S 300  of determining whether or not an absolute value of an internal pressure in the fuel tank T is less than a specific value, the internal pressure in the fuel tank T is sensed through the pressure gauge mounted on the fuel tank T. The absolute value of the sensed internal pressure in the fuel tank T compares with a predetermined specific value. 
     When the absolute value of the internal pressure in the fuel tank T is less than the specific value, the step S 400  of checking the leakage in fuel system is performed. In the step S 400  of checking the leakage in the fuel system, the switching valve  790  is operated. As shown in  FIG. 7 , the flowing air generated in the canister  100  and the fuel tank T caused by reverse-rotation of the active purge pump  300  is discharged to the atmosphere through the first port  710 , the front end of the first flow path  740  with reference to the switching valve  790 , the switching valve  790 , the rear end of the first flow path  740  with reference to the switching valve  790 , the second port  720 , the filter  600 , and the vent line  500 . 
     As shown in  FIG. 8 , the value obtained by converting the signal continuously generated in the pressure sensor  772  into a figure nonlinearly decreases depending on various environmental variables and reaches a specific value. At this time, the reached specific value is measured as a leakage determination value P 2 . 
     After the leakage determination value P 2  is measured, the PCSV  400  is operated to be opened. As the PCSV  400  is opened, an outside air flows into the purge line  200 . As the outside air flows into the purge line  200 , as shown in  FIG. 8 , the value obtained by converting the signal continuously generated in the pressure sensor  772  into a figure nonlinearly increases depending on various environment variables, and is the same as that obtained by converting the signal generated into a figure when the atmospheric pressure is measured in the step S 100  of determining whether or not the vacuum pump  750  fails in advance. The failure of the PCSV  400  is diagnosed based on the nonlinear change in the intensity of the signal generated in the pressure sensor  772 , in a state where the PCSV  400  is open. 
     When intensity of the signal continuously generated in the pressure sensor  772  is the same intensity as that of the signal generated when the atmospheric pressure is measured, the switching valve  790  is operated to be in a non-operated state and the PCSV  400  is also operated to be closed. Since the switching valve  790  is in a non-operated state, the air in the ELCM module  700  is recirculated and the value obtained by converting the signal generated in the pressure sensor  772  into a figure reaches a constant value depending on various environment variables as in the step S 200  of reverse-rotating the active purge pump  300 . This reached value is measured as a second reference pressure value P 3 . 
     The first reference pressure value P 1  and the second reference pressure value P 3  are compared with each other to check malfunction of the ELCM module  700 . When the leakage determination value P 2  is less than the first reference pressure value P 1  measured in the step S 200  of reverse-rotating the active purge pump  300  in advance, it is determined that the leakage in the fuel system does not occur. When the leakage determination value P 2  is more than the first reference pressure value P 1 , it is determined that the leakage in the fuel system occurs. 
     When it is determined that the absolute value of the internal pressure in the fuel tank T is not less than the specific value in the step S 300  of determining whether or not the absolute value of the internal pressure in the fuel tank T is less than the specific value, or when it is determined that the leakage in the fuel system occurs in the step S 400  of checking the leakage in the fuel system, the step S 500  of checking whether or not the leakage in the canister  100  occurs is performed. In the step S 500  of checking whether or not the leakage in the canister  100  occurs, the measurement target is limited to the canister  100 . Accordingly, a valve mounted on a line connecting the canister  100  and the fuel tank T to each other is locked, so that the air flow caused by reverse-rotating of the active purge pump  300  is not generated in the fuel tank T. 
     The switching valve  790  is operated again. As shown in  FIG. 7 , the flowing air generated in the canister  100  is discharged to the atmosphere through the first port  710 , the front end of the first flow path  740  with reference to the switching valve  790 , the switching valve  790 , the rear end of the first flow path  740  with reference to the switching valve  790 , the second port  720 , and the vent line  500  by operating the switching valve  790 . 
     At this time, the air existing in the second flow path  760  is flowed into the first flow path  740  through the first branch point D 1  and the second branch point D 2 . Accordingly, as shown in  FIG. 8 , the intensity of the signal shows an aspect in which the value obtained by converting the signal continuously generated in the pressure sensor  772  into a figure nonlinearly decreases and reaches the specific value. At this time, the reached specific value is measured as a leakage determination value P 2 . 
     After the leakage determination value P 2  is measured, the PCSV  400  is operated to be opened. As the PCSV  400  is opened, an outside air flows into the purge line  200 . As the outside air flows into the purge line  200 , as shown in  FIG. 8 , the value obtained by converting the signal continuously generated in the pressure sensor  772  into a figure nonlinearly increases and the intensity of the signal is the same as that of the signal generated when the atmospheric pressure is measured in the step of determining whether or not the vacuum pump  750  fails in advance. The failure of the PCSV  400  is diagnosed based on the change of the nonlinear signal generated in the pressure sensor  772 , in a state where the PCSV  400  is open. 
     In addition, the switching valve  790  is operated to be in a non-operated state and the PCSV  400  is also operated to be closed. The switching valve  790  is in a non-operated state, so that the air is circulated in the ELCM module  700  as in the step S 200  of reverse-rotating the active purge pump  300 . At this time, the second reference pressure value P 3  is measured through the pressure sensor  772 . 
     The first reference pressure value P 1  and the second reference pressure value P 3  are compared with each other to check malfunction of the ELCM module  700 . When the leakage determination value P 2  is less than the first reference pressure value P 1  measured in the step S 200  of reverse-rotating the active purge pump  300  in advance, it is determined that the leakage in the canister  100  does not occur and, at the same time, it is determined that the leakage in fuel tank T occurs. When the leakage determination value P 2  is more than the first reference pressure value P 1 , it is determined that the leakage in the canister  100  occurs. 
     In such a configuration, according to a leakage diagnosis supplement method for a failure of a vacuum pump  750  using an active purge pump  300  and a leakage diagnosis supplement system for a failure of the vacuum pump  750  using the active purge pump  300  of one form of the present disclosure, even when the vacuum pump  750  mounted on the ELCM module  700  fails, air flow may be generated in the ELCM module  700 , the canister  100 , and the fuel tank T by reverse-rotating the active purge pump  300 , and thus the fuel system leakage determination of the hybrid vehicle may be performed.