JP4092970B2 - Failure diagnosis device for fuel vapor purge system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention, BurningThe present invention relates to a failure diagnosis apparatus for a fuel vapor purge system that purges fuel vapor generated in a fuel tank into an intake system.
[0002]
[Prior art]
In general, a so-called fuel vapor purge system is employed in a vehicle having a tank of volatile liquid fuel. In a typical purge system, the fuel vapor generated in the fuel tank is introduced into the canister through the vapor passage and collected, and the collected fuel vapor is purged (released) into the intake passage of the internal combustion engine through the purge passage. Is done.
[0003]
In order to ensure the reliability of such a fuel vapor purge system, many purge systems include perforations and tears in the evaporation path (including a fuel tank, a vapor path, a canister, and a purge path). In order to detect leaks caused by the failure diagnosis device including the electronic control device is incorporated. In order to diagnose such a leak, after a differential pressure is provided between the inside and the outside of the evaporation path, the behavior of the internal pressure is detected. Then, by comparing the internal pressure determination level in a state where there is no leakage of the evaporation path and the behavior of the detected internal pressure, it is possible to diagnose the leakage failure of the evaporation path.
[0004]
When performing a failure diagnosis of such a fuel vapor purge system, for example, if pressure fluctuations in the evaporation path occur due to fuel level fluctuation or the like, the accuracy of the failure diagnosis decreases. The diagnosis accuracy can be improved by carrying out the operation while the vehicle-mounted internal combustion engine is stopped and the vehicle is stable.
[0005]
Therefore, a clock device is mounted on an electronic control device mounted on the vehicle, and power is supplied to the clock device without passing through an ignition switch. And, when the on-vehicle internal combustion engine is stopped, the time of the ignition switch OFF period is measured by the clock device, and when the measurement time reaches a predetermined time, the electronic control device is supplied with power, and the electronic control device is started. It is conceivable to perform failure diagnosis of the fuel vapor purge system without operating the on-vehicle internal combustion engine.
[0006]
[Problems to be solved by the invention]
However, even when the in-vehicle internal combustion engine is stopped, the vehicle is not always stationary, and the vehicle is not moving by itself because it is transported or towed, but the vehicle is moving. is there. In such a case, if the electronic control unit is activated to perform a fault diagnosis of the fuel vapor purge system, a disturbance that affects the pressure in the evaporation path will occur as the vehicle moves, and the fault diagnosis accuracy will be increased. Will be reduced.
[0008]
  The present invention has been made in view of the above circumstances, and itsIt is an object of the present invention to provide a fuel vapor purge system failure diagnosis device capable of improving the accuracy of diagnosis when a failure diagnosis of a fuel vapor purge system is executed while an on-vehicle internal combustion engine is stopped in an off state of an ignition switch. There is.
[0009]
[Means for Solving the Problems]
  In the following, means for achieving the above object and its effects are described.
  The invention described in claim 1An evaporation path is formed including a fuel tank and a canister mounted on a vehicle, fuel vapor generated in the fuel tank is collected in the canister, and the fuel vapor collected in the canister is purged to the intake passage of the internal combustion engine A fuel vapor purge system comprising:Power supply means for supplying operation power based on the establishment of a predetermined condition while the on-vehicle internal combustion engine is stopped in the off state of the ignition switch;A failure diagnosis unit that operates based on supply of operating power by the power supply unit and that diagnoses a failure in the evaporation path based on a pressure change in the evaporation path after providing a differential pressure inside and outside the evaporation path; ,Operating based on supply of operating power by the power supply means, detecting means for detecting a predetermined state quantity based on the position of the vehicle or movement of the vehicle, and operating based on the supply of operating power by the power supply means Stationary determination means for determining whether the vehicle is stationary based on a detection result of the detection means;Diagnosis prohibiting means for prohibiting failure diagnosis by the failure diagnosis means when the stationary determination means determines that the vehicle is not stationary;WithFailure diagnosis of fuel vapor purge systemThe gist of the apparatus.
[0010]
The failure diagnosis of the fuel vapor purge system is performed based on the pressure change in the evaporation path after the differential pressure is provided inside and outside the evaporation path including the fuel tank and the canister. Even when the in-vehicle internal combustion engine is stopped when performing failure diagnosis of the fuel vapor purge system, if the vehicle is not stationary, for example, fluctuations in the pressure in the evaporation path may occur due to fluctuations in the fuel level, etc. Diagnosis accuracy is reduced.
In this regard, according to the above configuration, when a predetermined condition is satisfied while the on-vehicle internal combustion engine is stopped in the off state of the ignition switch, the operation power is supplied and the stationary determination unit is activated, and the position of the vehicle by the detection unit or the vehicle It is determined whether the vehicle is stationary based on the detection result of the predetermined state quantity based on the movement of the vehicle. When it is determined that the vehicle is not stationary, failure diagnosis of the evaporation path by the failure diagnosis means is prohibited, so that the accuracy of failure diagnosis is improved.
[0011]
  The invention described in claim 2The failure diagnosis apparatus for a fuel vapor purge system according to claim 1,The power supply means operates based on a standby power supply, continuously measures an elapsed time after the ignition switch is turned off, and supplies the operating power when the measurement time reaches a predetermined time. The gist is that the timer performs.
[0012]
According to this configuration, when the elapsed time after the ignition switch is turned off reaches a predetermined time, the operation power is supplied, the detection means is activated, the stationary determination means is activated, and the detection means is detected. It is determined whether the vehicle is stationary based on the result.
[0013]
  The invention described in claim 3 is described in claim 1 or 2.Failure diagnosis of fuel vapor purge systemIn the apparatus, the detection means is a pressure sensor that detects a pressure in the fuel tank based on movement of the vehicle, and the stationary determination means integrates a change acceleration of the pressure in the fuel tank over a predetermined period, The gist is that the vehicle is determined to be stationary based on the value being less than the predetermined value.
[0014]
In a state where the vehicle is not stationary and is moving, the fuel level in the fuel tank is shaken due to vibration accompanying the movement, and the pressure in the fuel tank fluctuates. Therefore, it is possible to determine whether the vehicle is stationary by detecting the pressure fluctuation in the fuel tank. Note that since the pressure in the fuel tank fluctuates even under the influence of the outside air temperature, it is necessary to determine whether or not the vehicle is stationary in consideration of the fluctuation of the pressure in the fuel tank due to this heat.
[0015]
According to this configuration, the change acceleration of the pressure in the fuel tank during a predetermined period is integrated, and it is determined whether the vehicle is stationary based on the integrated value being less than the predetermined value. Therefore, it is possible to determine whether or not the vehicle is stationary in consideration of the fluctuation of the pressure in the fuel tank due to the influence of the outside air temperature.
[0016]
  Invention of Claim 4 is described in Claim 1 or 2.Failure diagnosis of fuel vapor purge systemIn the apparatus, the detection means is a global positioning system that detects the position of the vehicle based on a position signal output from an artificial satellite, and the stationary determination means is configured such that a change in the position of the vehicle in a predetermined period is a predetermined value. The gist is that the vehicle is determined to be stationary based on the fact that the vehicle is less than
[0017]
According to this configuration, since the global positioning system is used as the detecting means, the position of the vehicle can be easily detected, and whether or not the vehicle is stationary is reliably determined based on the detection result. be able to.
[0018]
  Invention of Claim 5 is described in Claim 1 or 2.Failure diagnosis of fuel vapor purge systemIn the apparatus, the detection means is an acceleration sensor that detects an acceleration acting on the vehicle based on movement of the vehicle, and the stationary determination means is that the acceleration sensor detects that the acceleration is zero. Based on this, it is determined that the vehicle is stationary.
[0019]
According to this configuration, the acceleration accompanying the movement of the vehicle can be detected by the acceleration sensor, and whether or not the vehicle is stationary can be reliably determined based on the detection result.
[0020]
  Invention of Claim 6 is described in Claim 1 or 2.Failure diagnosis of fuel vapor purge systemIn the apparatus, the detection means is a vehicle speed sensor that detects the vehicle speed of the vehicle, and the stationary determination means is configured to stop the vehicle based on the fact that the vehicle speed sensor detects that the vehicle speed is zero. The gist is that it is determined to be.
[0021]
According to this configuration, the vehicle speed associated with the movement of the vehicle can be detected by the vehicle speed sensor, and whether or not the vehicle is stationary can be reliably determined based on the detection result.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in which the present invention is embodied in a failure diagnosis device for a fuel vapor purge system mounted on a vehicle or the like will be described below with reference to the drawings.
[0026]
FIG. 1 is a schematic configuration diagram illustrating a fuel vapor purge system and a failure diagnosis device thereof according to the present embodiment.
As shown in FIG. 1, a surge tank 12 is provided in an intake passage 11 that guides intake air to an engine 10 as an in-vehicle internal combustion engine, and a throttle valve 13 is provided upstream of the surge tank 12. An air cleaner 14 is provided in the intake passage 11 on the upstream side of the throttle valve 13.
[0027]
A fuel vapor purge system 20 shown in FIG. 1 constitutes a part of an engine, and a canister 22 that adsorbs fuel vapor generated in a fuel tank 21, an evaporation passage 23 that communicates the fuel tank 21 and the canister 22, and The canister 22 and the purge passage 24 communicating with the intake passage 11 are provided. The fuel vapor purge system 20 includes an air introduction passage 25 that introduces air into the canister 22.
[0028]
A fuel supply pipe 26 for refueling is attached to the fuel tank 21. A cap 27 is attached to the oil supply port of the oil supply pipe 26, and a check valve 28 is provided at the outlet thereof. In addition, a circulation path 29 is branched from the fuel supply pipe 26, and an opening end of the circulation path 29 is open to an upper space in the fuel tank 21.
[0029]
In addition to the circulation path 29, one end side of the evaporation path 23 is provided on the upper wall of the fuel tank 21. The same end side is branched into two passages, and a float valve 31, a liquid reservoir 32, and a throttle 33 are sequentially provided in one passage from the opening end side of the passage. In the other passage, a float valve 34 and a liquid reservoir 35 are sequentially provided from the opening end side of the passage.
[0030]
An internal pressure valve 36 and a throttle 37 are provided in the vicinity of the canister 22 in the evaporation passage 23. When the pressure in the fuel tank 21 is lower than the opening pressure of the internal pressure valve 36, the internal pressure valve 36 and the throttle 37 have the diaphragm of the internal pressure valve 36 in the closed position, and the fuel tank 21 and the canister 22 Communicate through.
[0031]
On the other hand, when the pressure in the fuel tank 21 reaches the valve opening pressure of the internal pressure valve 36, the diaphragm of the internal pressure valve 36 is displaced to the valve opening position against the biasing force, and the fuel vapor generated in the fuel tank 21 is throttled. Instead of passing through 37, it is sent to the canister 22 through the evaporation passage 23. In the present embodiment, the diaphragm of the internal pressure valve 36 is biased by a spring (not shown), and atmospheric pressure is applied to the diaphragm. With such a configuration, the fuel vapor generated in the fuel tank 21 is sent to the canister 22 through the evaporation passage 23 and the throttle 37 until the pressure in the fuel tank 21 reaches the valve opening pressure of the internal pressure valve 36.
[0032]
The canister 22 has an adsorbent therein. The canister 22 is configured such that the fuel vapor adsorbed by the adsorbent can be re-detached when the canister 22 is adsorbed on the adsorbent and temporarily stored and then placed under a negative pressure. The interior of the canister 22 is partitioned into two adsorbent chambers 41 and 42 by a partition plate 40. Both adsorbent chambers 41 and 42 are each filled with an adsorbent and communicated with each other through a breathable filter 43. The adsorbent chamber 41 communicates with the fuel tank 21 via the evaporation passage 23 and also communicates with the surge tank 12 of the intake passage 11 via the purge passage 24. On the other hand, the adsorbent chamber 42 communicates with the air introduction passage 25. The canister 22 is provided with a guide member 44 so that the fuel vapor flowing from the fuel tank 21 is once introduced into the purge passage 24 after passing through the adsorbent.
[0033]
A purge control valve 46 composed of an electromagnetic valve is provided in the middle of the purge passage 24. The purge control valve 46 is always closed. When the control valve 46 is opened during operation of the engine 10, the intake negative pressure generated in the surge tank 12 is passed through the purge passage 24 in the canister 22. To be introduced.
[0034]
On the other hand, the air introduction passage 25 communicates between an inlet port 48 provided in an opening for refueling that is opened and closed by a fuel lid (not shown) and a fresh air introduction port 22a (see FIGS. 2 and 3) of the canister 22. Air entering from the mouth 48 is introduced into the canister 22. An atmospheric dustproof filter 49 is provided in the middle of the atmospheric introduction passage 25. An electric pump module 50 constituting a differential pressure applying means is provided at a connection portion between the air introduction passage 25 and the fresh air introduction port 22 a of the canister 22.
[0035]
As shown in FIGS. 2 and 3, the electric pump module 50 includes an electric air pump 51 connected to an air intake port 25 a branched from the air introduction passage 25. The electric pump module 50 is an electromagnetic switching valve for selectively connecting the fresh air inlet 22a of the canister 22 to the atmosphere opening 25b of the atmosphere introduction passage 25 and the outlet 51a of the electric air pump 51. 52. Further, a bypass passage 53 is provided from the discharge port 51a of the electric air pump 51 to the bypass valve 52 to reach the fresh air introduction port 22a of the canister 22, and the bypass passage 53 has a reference diameter (for example, 0.5 mm). A reference hole 54 is provided. An air filter 55 is provided at each of the air suction port 25a, the downstream of the reference hole 54, and the discharge port 51a of the electric air pump 51.
[0036]
The switching valve 52 is switched to the atmosphere opening port 25b side in the off state and switched to the electric air pump 51 side in the on state, and is normally switched to the atmosphere opening port 25b side in the off state. The introduction port 22a communicates with the atmosphere opening port 25b.
[0037]
Further, a check valve 56 as a shut-off means is provided upstream of the bypass passage 53 at the discharge port 51 a of the electric air pump 51. The check valve 56 opens only when the pressure of the discharge port 51a of the electric air pump 51 is higher than the pressure of the evaporation path, and allows the air flow from the electric air pump 51 to the evaporation path side. Conversely, when the pressure at the discharge port 51a of the electric air pump 51 is lower than the pressure in the evaporation path, the check valve 56 is closed to block communication between the evaporation path and the outside air.
[0038]
Further, a pressure sensor 57 is provided between the check valve 56 and the switching valve 52 to detect the pressure in the evaporation path and output an electrical signal corresponding to the detected pressure. An absolute pressure sensor is used as the pressure sensor 57.
[0039]
In the fuel vapor purge system 20 configured as described above, the fuel vapor generated in the fuel tank 21 is sent to the canister 22 through the evaporation passage 23 and is adsorbed by the canister 22. When the purge control valve 46 is opened, the negative pressure in the surge tank 12 is supplied to the canister 22 through the purge passage 24. At this time, the atmosphere is introduced into the canister 22 via the atmosphere introduction passage 25, the atmosphere dust filter 49, the atmosphere opening port 25b, the switching valve 52, and the fresh air introduction port 22a. By introducing the atmosphere in this way, the adsorbed fuel vapor is purged (released) from the canister 22 to the surge tank 12.
[0040]
Further, when the switching valve 52 is switched to the electric air pump 51 side with the purge control valve 46 closed while the engine 10 is stopped and the vehicle is stopped, the fuel vapor purge system 20, that is, the evaporation The route is a closed space. Here, the “evaporation path” of the fuel vapor purge system 20 is a path including a passage portion between the canister 22 and the purge control valve 46 among the fuel tank 21, the evaporation path 23, the canister 22, and the purge path 24. It is. Thus, a failure diagnosis process described later is performed in a state where the “evaporation path” of the fuel vapor purge system 20 is closed.
[0041]
In the engine, the fuel vapor purge system 20 and the failure diagnosis apparatus configured as described above, an electronic control unit (hereinafter referred to as an ECU) 60 that controls each part is provided.
[0042]
The ECU 60 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, and signals are input from various sensors. As various sensors, in addition to the pressure sensor 57, a vehicle speed sensor 65 for detecting a vehicle speed during travel of the vehicle, and an acceleration sensor 66 used for a vehicle stability control system and an airbag system are provided. The acceleration sensor 66 detects acceleration acting on the vehicle based on the movement of the vehicle. Various sensors include a crank angle sensor that can detect the rotational speed of the engine 10, an air flow meter that detects the intake air amount, an air-fuel ratio sensor that detects the air-fuel ratio in the engine exhaust system, and the like.
[0043]
Connected to the ECU 60 is a global positioning system (GPS) 64 as detection means for detecting whether the vehicle is stationary. The GPS 64 detects the position of the GPS 64, that is, the position of the vehicle, based on a position signal output from an artificial satellite orbiting the earth.
[0044]
An ignition switch (hereinafter referred to as an IG switch) 63 is connected to the ECU 60. When the IG switch 63 is turned on, operating power is supplied to the ECU 60 to start the ECU 60 and start the engine 10. It has become.
[0045]
When the ECU 60 is activated based on the ON operation of the IG switch 63, the ECU 60 starts the operation of the engine 10, and the engine such as the fuel injection control and the ignition timing control is based on the outputs of various sensors that are taken in during the operation of the engine 10. Various controls relating to the ten operations are executed. Further, during the operation of the engine 10, the ECU 60 performs the purge control process of the fuel vapor purge system 20 by drivingly controlling the purge control valve 46, the electric air pump 51, the switching valve 52, and the like.
[0046]
The ECU 60 also includes a timer IC 62 as power supply means. The timer IC 62 operates based on the standby power supply. When the engine 10 is stopped based on the turning-off operation of the ignition switch 63, the elapsed time during the stop is continuously measured. When the measurement time reaches a predetermined time td (for example, 5 hours in this embodiment), the timer IC 62 supplies the operation power to the ECU 60 to start the ECU 60. Note that the measurement time of the timer IC 62 is reset based on the ON operation of the ignition switch 63. Therefore, it can be determined whether the ignition switch 63 is on or off based on the measurement time of the timer IC 62.
[0047]
When the ECU 60 is started by the timer IC 62 while the engine 10 is stopped when the IG switch 63 is off, the ECU 60 executes a stationary determination process for the vehicle and a fault diagnosis process for the fuel vapor purge system 20.
[0048]
In the failure diagnosis of the fuel vapor purge system 20, a factor that hinders the accuracy of the diagnosis is the fluctuation of the fuel level in the fuel tank. When the vehicle vibrates due to the movement of the vehicle, the fuel level in the fuel tank may shake. When such a fluctuation of the fuel liquid level occurs, the internal pressure of the evaporation path changes inadvertently in response. Further, when such fluctuation of the fuel liquid level occurs, fuel evaporation is promoted by fuel agitation, fuel adhesion to the fuel tank wall surface, and the like, for example, the internal pressure P of the evaporation path increases at a time. Therefore, if the fuel level fluctuates during the failure diagnosis, the accuracy of the diagnosis performed by monitoring the change over time in the internal pressure is greatly reduced. Therefore, in this embodiment, when the ECU 60 is activated by the timer IC 62, it is determined whether or not the vehicle is stationary.
[0049]
In the present embodiment, the stationary determination of the vehicle while the engine 10 is stopped is performed by adopting a plurality of methods described below.
1) The vehicle speed sensor 65 detects the vehicle speed. If the detected vehicle speed is zero, it can be determined that the vehicle is stationary, and if the detected vehicle speed is not zero, it can be determined that the vehicle is moving. According to this determination method, it is possible to determine that the vehicle is moving even when the vehicle is not traveling and is being towed.
[0050]
2) Acceleration acting on the vehicle is detected based on the movement of the vehicle by the acceleration sensor 66 used in the airbag system. If the detected acceleration is zero, it can be determined that the vehicle is stationary, and if the detected acceleration is not zero, it can be determined that the vehicle is moving. According to this determination method, it is possible to determine that the vehicle is moving even when the vehicle is transported regardless of whether the vehicle is traveling.
[0051]
3) The change in the position of the vehicle detected by the GPS 64 is calculated. If the amount of change in the position of the vehicle in a predetermined period is less than a predetermined value, it can be determined that the vehicle is stationary. If the amount of change in the position of the vehicle is equal to or greater than a predetermined value, the vehicle is moving. Can be determined. According to this determination method, it is possible to determine that the vehicle is moving even when the vehicle is transported regardless of whether the vehicle is traveling.
[0052]
4) As described above, when the vehicle vibrates due to the movement of the vehicle, the liquid level of the fuel in the fuel tank fluctuates, and the pressure in the evaporation path fluctuates due to the fluctuation of the fuel liquid level. In other words, this means that if the pressure fluctuation in the evaporation path is equal to or greater than a predetermined value, it can be determined that the vehicle is moving. Therefore, the pressure in the evaporation path is detected by the pressure sensor 57. If the pressure fluctuation is less than a predetermined value, it can be determined that the vehicle is stationary. If the integrated value is equal to or greater than the predetermined value, the vehicle is It can be determined that it is moving.
[0053]
Specifically, after the ECU 60 is started by the timer IC 62, as shown in FIG. 4B, the pressure in the evaporation path is detected by the pressure sensor 57, and the second-order difference value of the change amount of the pressure in a predetermined minute time is detected. A certain pressure change acceleration ΔΔP is calculated. As shown in FIG. 4C, when the integrated value (swing amount) Σ | ΔΔP | of the pressure change acceleration becomes equal to or greater than a predetermined value thα within a predetermined time TG (for example, 30 seconds), ), It is determined that there is vibration of the vehicle and the vehicle is moving.
[0054]
Further, as shown in FIG. 5 (b), the pressure in the evaporation path is detected by the pressure sensor 57, and as shown in FIG. 5 (c), the fluctuation amount Σ | ΔΔP | is within a predetermined time TG (for example, 30 seconds). If it is less than the predetermined value thα, it is determined that there is no vibration of the vehicle and the vehicle is stationary as shown in FIG.
[0055]
FIG. 6 is a flowchart showing a procedure for calculating the shaking amount Σ | ΔΔP | executed by the ECU 60. With reference to FIG. 6, how the shaking amount Σ | ΔΔP | is calculated will be described. . This routine is periodically executed at predetermined intervals by the ECU 60 immediately after the ECU 60 is started by the timer IC 62.
[0056]
When the processing shifts to this routine, first, at step 210, whether or not the shaking amount Σ | ΔΔP | obtained at that time is equal to or larger than a predetermined value thα, or the shaking amount Σ | ΔΔP | Is accumulated over time. If none of these conditions is satisfied, it is further determined in step 240 whether or not it is time to calculate the shaking amount Σ | ΔΔP |. If it is determined that it is not the time, the routine is temporarily exited. . That is, here, the fluctuation amount Σ | ΔΔP | is calculated once every several cycles of the routine, and the routine is temporarily exited until the calculation cycle is reached.
[0057]
On the other hand, if it is determined in step 240 that it is time to calculate the shaking amount Σ | ΔΔP |, first, in step 250, the pressure change acceleration ΔΔP of the evaporation path is calculated, and in the next step 260, the integrated value is calculated. A certain amount of shaking Σ | ΔΔP | is calculated. When the swing amount Σ | ΔΔP | is calculated in this way, the ECU 60 then exits the routine once.
[0058]
On the other hand, when it is determined in the previous step 210 that the fluctuation amount Σ | ΔΔP | is equal to or greater than the predetermined value thα, or when it is determined that the fluctuation amount Σ | ΔΔP | is accumulated over a predetermined time TG, In step 220, the value of the shaking amount Σ | ΔΔP | previously calculated through the routine is stored in the RAM. In step 230 thereafter, the value of the shaking amount Σ | ΔΔP | referred to this time is cleared to “0”.
[0059]
By repeatedly executing such processing through the routine for calculating the amount of swing Σ | ΔΔP |, the change in the internal pressure of the evaporation path illustrated in FIGS. 4B and 5B is shown in FIG. ), The shaking amount Σ | ΔΔP | is calculated in the manner illustrated in FIG.
[0060]
Next, the vehicle stationary determination process and the failure diagnosis process procedure of the fuel vapor purge system 20 executed by the ECU 60 will be described with reference to FIG.
First, at step 110, the timer IC 62 determines whether the IG switch 63 is off. When the timer IC 62 is not reset, it is determined that the IG switch 63 is off. When the timer IC 62 is reset, it is determined that the IG switch 63 is on. If it is determined that the IG switch 63 is on ("NO" in step 110), in this case, since the ECU 60 is activated by turning on the IG switch 63, normal control during engine operation is performed. The
[0061]
On the other hand, if it is determined that the IG switch 63 is off (“YES” in step 110), it is determined by the timer IC 62 whether or not a predetermined time td has elapsed since the engine 10 was stopped (step 120). If the measurement time of the timer IC 62 has not elapsed the predetermined time td (“NO” in step 120), this process is temporarily terminated.
[0062]
If it is determined that the predetermined time td has elapsed since the engine 10 was stopped (“YES” in step 120), the operation power is supplied to the ECU 60 by the operation of the timer IC 62, and the ECU 60 is started (step 130).
[0063]
When the ECU 60 is activated by the timer IC 62, it is next determined whether or not the vehicle is in a stationary state (step 140). Conditions for determining the stationary state of the vehicle are whether the vehicle speed detected by the vehicle speed sensor 65 is zero, whether the acceleration detected by the acceleration sensor 66 is zero, and the amount of shaking described above is less than the predetermined value thα. And whether there is any change in the position detection result by the GPS 64. If all of these determination conditions are satisfied, it is determined that the vehicle is stationary. If any one of the plurality of determination conditions is not satisfied, it is determined that the vehicle is moving regardless of whether the vehicle is traveling.
[0064]
When it is determined that the vehicle is stationary (“YES” in step 140), the ECU 60 controls the purge control valve 46, the electric air pump 51, the switching valve 52, and the like, thereby diagnosing the failure of the fuel vapor purge system 20. The process is executed (step 150).
[0065]
Next, the ECU 60 determines whether the diagnosis is completed (step 160). If it is determined that the failure diagnosis has not been completed (“NO” in step 160), the process returns to step 140. If it is determined that the failure diagnosis has been completed (“YES” in step 160), the process proceeds to step 170.
[0066]
On the other hand, when it is determined in step 140 that the vehicle is in a moving state (“NO” in step 140), the ECU 60 prohibits the failure diagnosis process of the fuel vapor purge system 20 (step 180), and the process proceeds to step 170. Accordingly, the failure diagnosis is prohibited when it is detected that the vehicle is not in a stationary state regardless of whether or not the failure diagnosis of the fuel vapor purge system 20 is started.
[0067]
In step 170, the ECU 60 stops the ECU 60 itself by stopping the supply of operating power, and outputs a reset signal to the timer IC 62 to reset the measurement time of the timer IC 62. That is, when the diagnosis process of the fuel vapor purge system 20 is completed or the failure diagnosis process is prohibited, the ECU 60 is automatically stopped.
[0068]
FIG. 8 is a time chart showing one aspect of the vehicle stationary determination process and the failure diagnosis process of the fuel vapor purge system 20 executed by the ECU 60.
Assume that the ECU 60 is activated by turning on the IG switch 63, the engine 10 is operated, and the vehicle is running (moving). In this state, since the IG switch 63 is on, the timer IC 62 is reset. Further, since the ECU 60 is activated by turning on the IG switch 63, the failure diagnosis of the fuel vapor purge system 20 is not executed.
[0069]
Thereafter, when the vehicle stops and the IG switch 63 is turned off at time T1, the ECU 60 is stopped and the engine 10 is stopped. In addition, since the IG switch 63 is turned off, the elapsed time after the engine 10 is stopped is measured by the timer IC 62.
[0070]
When the IG switch 63 is kept off and the measurement time of the timer IC 62 reaches the predetermined time td at time T2, the ECU 60 is activated by the timer IC 62 and the GPS 64 is also activated. At this time, if it is determined that the vehicle is stationary based on the vehicle speed detection result by the vehicle speed sensor 65, the acceleration detection result by the acceleration sensor 66, the calculation result of the shake amount, and the position detection result by the GPS 64, A failure diagnosis of the fuel vapor purge system 20 is executed under the control of the ECU 60.
[0071]
When the failure diagnosis of the fuel vapor purge system 20 is completed at time T4, the ECU 60 stops the ECU 60 itself by stopping the supply of operating power, and resets the measurement time of the timer IC 62. If the IG switch 63 is maintained in the OFF state, the timer IC 62 starts to newly measure the time during which the engine 10 is stopped.
[0072]
Further, during the execution of the failure diagnosis, for example, it is assumed that the movement of the vehicle is determined as indicated by a chain line based on the detection result of the GPS 64 at time T3. Then, ECU 60 prohibits failure diagnosis of fuel vapor purge system 20 as indicated by a chain line at time T3. Further, in this case, at time T3, the ECU 60 stops the supply of the operating power supply, thereby stopping the ECU 60 itself and resetting the measurement time of the timer IC 62. If the IG switch 63 is maintained in the OFF state, the timer IC 62 starts to newly measure the time during which the engine 10 is stopped.
[0073]
At time T5 after time T4, when the IG switch 63 is turned on, the ECU 60 is activated and the engine 10 is operated. In this state, since the IG switch 63 is on, the timer IC 62 is reset.
[0074]
Next, the failure diagnosis process of the fuel vapor purge system executed by the ECU 60 will be described with reference to FIGS.
When the failure diagnosis process of the fuel vapor purge system 20 is executed, the purge control valve 46 is maintained in a closed state by a control command from the ECU 60. First, as shown in FIG. 2, the switching valve 52 is on the atmosphere opening 25b side. Then, the atmospheric pressure is introduced into the canister 22 through the atmospheric opening 25b and the atmospheric dust filter 49, so that the residual pressure (negative pressure) in the fuel vapor purge system 20 is removed. It becomes an atmospheric pressure state.
[0075]
Next, in a state where the operation of the electric air pump 51 is stopped, the switching valve 52 is turned on and switched to the electric air pump 51 side as shown in FIG. Then, the inside of the fuel vapor purge system 20 is sealed, and a closed space is formed. At this time, a change in the pressure Pb in the evaporation path due to the fuel vapor generated in the fuel tank 21 is detected by the pressure sensor 57. The detection time TPb (see FIG. 9) of the amount of generated fuel vapor is set to a short time (for example, 1 minute).
[0076]
Thereafter, as shown in FIG. 2, the electric air pump 51 is operated with the switching valve 52 turned off and switched to the atmosphere opening 25b side. At this time, the air sucked and discharged by the electric air pump 51 passes through the bypass passage 53 (reference hole 54), then flows backward through the switching valve 52 and is discharged into the atmosphere from the atmosphere opening port 25b.
[0077]
In this state, the pressure of the bypass passage 53 extending from the electric air pump 51 to the reference hole 54 is detected by the pressure sensor 57, and this detected pressure is used as a reference value Pr0 (see FIG. 9) for determining a leakage failure in the evaporation path. Desired. That is, the reference hole 54 is set to the size of the hole to be detected by the fuel vapor purge system 20 and detects a decrease in pressurization capacity accompanying the deterioration with time of the electric air pump 51 when there is a leakage failure in the evaporation path. can do. Since the length of the bypass passage 53 from the electric air pump 51 to the reference hole 54 is shortened, the pressure in this portion due to the operation of the electric air pump 51 is saturated in an extremely short time, and this reference value detection is performed. The predetermined operating time TPr (see FIG. 9) of the electric air pump 51 at the time may be short. In the present embodiment, the operation time TPr of the electric air pump 51 is set equal to the reference value detection period.
[0078]
Thereafter, as shown in FIG. 3, the electric air pump 51 is operated in a state where the switching valve 52 is turned on and switched to the electric air pump 51 side. At this time, the air drawn and discharged by the electric air pump 51 passes through the switching valve 52, passes through the canister 22 from the fresh air inlet 22 a of the canister 22, and passes through the canister 22 to the purge control valve 46 through the canister 22. 24 flows in.
[0079]
In this state, the pressure in the evaporation path is detected by the pressure sensor 57, and this detected pressure is obtained as a comparison value Pf (see FIG. 9) of the fuel vapor purge system 20. This part corresponds to the comparison value calculation means. Note that the volume of the evaporation path from the electric air pump 51 to the canister 22 and the fuel tank 21 varies depending on the remaining amount of fuel in the fuel tank 21. Therefore, the predetermined operation time TPf (see FIG. 9) of the electric air pump 51 at the time of detection of the comparison value is set to a value that can obtain a predetermined comparison pressure when the fuel in the fuel tank 21 is almost empty. ing. In the present embodiment, the operation time TPf of the electric air pump 51 is set equal to the comparison value detection period.
[0080]
The leakage failure of the fuel vapor purge system 20 is determined by comparing the latest comparison value Pf detected in the comparison value detection period TPf with the reference value Pr0. At this time, when the evaporation path is pressurized to calculate the comparison value Pf, the pressure change due to the fuel vapor generated in the fuel tank 21 is included, and when the reference hole Pr is pressurized to calculate the reference value Pr0, the fuel vapor is used. Pressure changes are not included. Therefore, the reference value Pr0 is corrected to a value Pr1 (see FIG. 9) to which the influence of the pressure due to the generation of the fuel vapor is added in consideration of the degree of influence due to the fuel vapor generated in the fuel tank 21. The pressure value (Pr1-Pr0) due to the fuel vapor applied here is increased according to the ratio of the operation time TPf of the electric air pump 51 and the detection time TPb of the fuel vapor generation amount at the time of comparison value detection.
[0081]
At the time of this comparison value detection, if it is determined that the comparison value Pf is larger than the corrected reference value Pr1 during the period when the electric air pump 51 is operated for a predetermined time TPf and the evaporation route is pressurized, the evaporation route Is determined to be normal (no holes). This part corresponds to the failure determination means. Conversely, if it is determined that the comparison value Pf is equal to or less than the corrected reference value Pr1 during the period when the electric air pump 51 is operated for a predetermined time TPf and the evaporation path is pressurized, the evaporation path is abnormal ( It is determined that there is a hole.
[0082]
FIG. 9 shows a failure diagnosis process of the fuel vapor purge system 20 when fuel vapor is generated in the fuel tank 21. As shown in FIG. 9, the pressure Pb due to the generation of the fuel vapor is detected in the detection time TPb of the generation amount of the fuel vapor. Next, the reference value Pr0 is calculated in the reference value detection period TPr.
[0083]
Therefore, in the comparison value detection period TPf, the reference value Pr0 is corrected to a value Pr1 to which the influence of pressure due to the generation of fuel vapor is added. In the comparison value detection period TPf, if the comparison value Pf is larger than the reference value Pr1, a normal determination that there is no hole in the evaporation path is performed, and the comparison value Pf is equal to or less than the reference value Pr1 at the end of the comparison value detection period TPf. If the value is, an abnormality determination is made that there is a hole in the evaporation path.
[0084]
FIG. 10 shows a failure diagnosis process of the fuel vapor purge system 20 when no fuel vapor is generated in the fuel tank 21. As shown in FIG. 7, the pressure Pb due to the generation of the fuel vapor is “0” in the detection time TPb of the generation amount of the fuel vapor.
[0085]
Therefore, the reference value Pr0 is used as it is as the reference value in the comparison value detection period TPf. Since the pressure Pb due to the generation of fuel vapor is “0”, the reference value Pr0 is merely maintained as it is after correction. In the comparison value detection period TPf, if the comparison value Pf is larger than the reference value Pr0, a normal determination that there is no hole in the evaporation path is performed, and the comparison value Pf is equal to or less than the reference value Pr0 at the end of the comparison value detection period TPf. If the value is, an abnormality determination is made that there is a hole in the evaporation path.
[0086]
According to the embodiment described in detail above, the following operational effects can be obtained.
When the elapsed time while the engine 10 is stopped when the IG switch 63 is off reaches the predetermined time td, the operation power is supplied by the timer IC 62 and the ECU 60 is activated, and the vehicle stops based on the detection result of the GPS 64 position. It can be determined whether or not. The ECU 60 executes the failure diagnosis process of the fuel vapor purge system 20 only when the vehicle is stationary, and prohibits the failure diagnosis process of the fuel vapor purge system 20 when the vehicle is moving. Yes. For this reason, for example, the influence of disturbance such as pressure fluctuation in the evaporation path caused by fuel level fluctuation or the like can be eliminated, and the accuracy of failure diagnosis can be improved.
[0087]
The pressure sensor 57 detects the pressure in the evaporation path, and the vehicle detects whether or not the integrated value (swing amount) Σ | ΔΔP | of the pressure change acceleration ΔΔP of the pressure is less than the predetermined value thα within the predetermined time TG. It can be reliably determined whether or not it is stationary. In addition, since the pressure sensor 57 for detecting the pressure in the evaporation path is used, it is not necessary to newly provide a pressure sensor, and an increase in cost can be suppressed.
[0088]
The position of the vehicle can be reliably detected by the GPS 64, and the ECU 60 can reliably determine whether the vehicle is stationary based on the detection result.
[0089]
The acceleration sensor 66 can detect the acceleration acting as the vehicle moves, and the ECU 60 can reliably determine whether the vehicle is stationary based on the detection result.
[0090]
The vehicle speed sensor 65 can detect the vehicle speed accompanying the movement of the vehicle, and can reliably determine whether the vehicle is stationary based on the detection result.
[0091]
A reference for determining a leak failure by correcting the reference value Pr0 calculated in consideration of the degree of influence of the fuel vapor generated in the fuel tank 21 on the failure determination when diagnosing a leakage failure in the evaporation path The value Pr1 is calculated, and the failure of the evaporation path is determined based on the reference value Pr1 and the comparison value Pf. Therefore, the influence of the pressure change caused by the generated fuel vapor can be offset, and the determination accuracy can be improved and the accurate determination of the leakage failure can be performed.
[0092]
Further, the leakage failure of the evaporation path is determined based on the comparison between the reference value Pr0 of the pressure when the reference hole 54 is pressurized and the comparison value Pf of the pressure when the evaporation path is pressurized. . Therefore, the pressure reference value for determining the leakage failure in the evaporation path can be made appropriate in consideration of the deterioration over time of the electric air pump 51, and the deterioration of the determination accuracy of the leakage failure can be prevented. .
[0093]
The discharge port 51a of the electric air pump 51 is provided with a check valve 56 that closes when the pressure of the discharge port 51a is lower than the pressure of the evaporation path and blocks communication between the evaporation path and the outside air. Therefore, when the amount of fuel vapor generated in the fuel tank 21 is detected and the comparison value for pressurizing the evaporation path is detected, the check valve 56 can prevent pressure leakage from the evaporation path.
[0094]
The pressure sensor 57 is disposed between the electric air pump 51 and the evaporation path / reference hole 54. Therefore, by switching the switching valve 52, the pressure sensor 57 can detect the pressure reference value and the pressure comparison value for determining the leakage failure in the evaporation path, and suppress the increase in the number of components. Can do.
[0095]
Since the electric air pump 51 that sends out air is used as the differential pressure applying means, the evaporation path can be pressurized by operating the electric air pump 51, and even when the engine 10 is stopped, the evaporation path Leakage failure can be determined.
[0096]
In addition, embodiment is not limited above, You may change as follows.
In the above embodiment, 1) the vehicle speed detected by the vehicle speed sensor 65 is zero, 2) the acceleration detected by the acceleration sensor 66 is zero, 3) there is no change in the position detection result by the GPS 64, and 4) the amount of shaking The vehicle is determined to be stationary when all the conditions that the vehicle is less than the predetermined value thα are satisfied. The conditions for determining the stationary state of the vehicle need not be limited to the above four, and may be limited to some of the conditions 1) to 4). For example, the determination condition for the stationary state of the vehicle may be that the amount of shaking is less than a predetermined value thα. That is, if the amount of shaking calculated based on the pressure in the evaporation path detected by the pressure sensor 57 is less than the predetermined value thα, it can be reliably determined that there is no vibration of the vehicle and the vehicle is stationary. This is because it can. Further, the determination condition of the stationary state of the vehicle may be, for example, that there is no change in the position detection result by the GPS 64. If there is no change in the position of the vehicle, it can be reliably determined that the vehicle is stationary. This is because it can.
[0097]
In the above embodiment, an atmospheric pressure sensor that detects atmospheric pressure may be provided, and it may be added as a condition for determining the stationary state of the vehicle that the change in atmospheric pressure is less than a predetermined value.
[0098]
In the above embodiment, the fuel tank 21 is provided with a liquid level sensor for detecting the liquid level fluctuation of the fuel, and a condition for determining the stationary state of the vehicle that the detection result of the liquid level sensor is less than a predetermined value. May be added as
[0099]
In the above embodiment, the vehicle stability control system also uses the yaw rate sensor that detects the rotational angular velocity of the vehicle in the vertical axis direction, and detects the rotation of the vehicle in the vertical axis direction based on the detection signal of the yaw rate sensor. It may be.
[0100]
In the above embodiment, the communication means is provided in the ECU 60, and when the ECU 60 is activated while the engine 10 is stopped when the IG switch 63 is in the off state, when it is determined that the vehicle is not stationary, for example, the vehicle is connected via the communication means. It is good also as a structure which issues an alarm to the owner's or administrator's mobile phone. If it does in this way, it can be used as a vehicle antitheft device.
[0101]
  Next, other technical ideas that can be grasped from the above embodiment will be described below.
  · Claim 1 or 2Failure diagnosis of fuel vapor purge systemIn the apparatus, the detection means is an atmospheric pressure sensor for detecting atmospheric pressure, and the stationary determination means determines that the vehicle is stationary based on a change in atmospheric pressure in a predetermined period being less than a predetermined value. It is characterized byFailure diagnosis of fuel vapor purge systemapparatus.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a failure diagnosis apparatus for a fuel vapor purge system according to an embodiment.
FIG. 2 is an explanatory view showing a state of the electric pump module when atmospheric pressure is introduced and when a reference hole is pressurized.
FIG. 3 is an explanatory view showing the state of the electric pump module when detecting the amount of fuel vapor generated and when pressurizing the evaporation path.
FIG. 4 is a time chart showing a vehicle stationary monitoring mode according to the embodiment.
FIG. 5 is a time chart showing a vehicle stationary monitoring mode according to the embodiment.
FIG. 6 is a flowchart showing a procedure for calculating a shaking amount Σ | ΔΔP | according to the embodiment;
FIG. 7 is a flowchart illustrating a vehicle stationary determination process and a failure diagnosis process according to the embodiment.
FIG. 8 is a time chart showing an aspect of a vehicle stationary determination process and a failure diagnosis process according to the embodiment;
FIG. 9 is a time chart showing a failure determination operation when fuel vapor is generated.
FIG. 10 is a time chart showing a failure determination operation when no fuel vapor is generated.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Engine (internal combustion engine), 11 ... Intake passage, 20 ... Fuel vapor purge system, 21 ... Fuel tank, 22 ... Canister, 22a ... Fresh air inlet, 25b ... Air release port, 51 ... Electric air pump, 52 ... Switching valve, 53 ... bypass passage, 54 ... reference hole, 56 ... check valve, 57 ... pressure sensor as detection means, 60 ... stationary control means, failure diagnosis means and electronic control unit (ECU) as diagnosis prohibition means, 62 ... Timer IC as power supply means, 63 ... Ignition switch (IG switch), 64 ... Global positioning system (GPS) as detection means, 65 ... Vehicle speed sensor as detection means, 66 ... Acceleration sensor as detection means .

Claims (6)

An evaporation path is formed including a fuel tank and a canister mounted on a vehicle, fuel vapor generated in the fuel tank is collected in the canister, and the fuel vapor collected in the canister is purged to the intake passage of the internal combustion engine A fuel vapor purge system comprising:
Power supply means for supplying operation power based on the establishment of a predetermined condition while the vehicle-mounted internal combustion engine is stopped in an off state of the ignition switch;
A failure diagnosis unit that operates based on supply of operating power by the power supply unit and that diagnoses a failure in the evaporation path based on a pressure change in the evaporation path after providing a differential pressure inside and outside the evaporation path; ,
Detecting means for operating based on supply of operating power by the power supply means and detecting a predetermined state quantity based on vehicle position or vehicle movement;
A stationary determination unit that operates based on the supply of operating power by the power supply unit, and determines whether the vehicle is stationary based on a detection result of the detection unit ;
Diagnosis prohibiting means for prohibiting failure diagnosis by the failure diagnosis means when the stationary determination means determines that the vehicle is not stationary,
A failure diagnosis apparatus for a fuel vapor purge system, comprising: The failure diagnosis apparatus for a fuel vapor purge system according to claim 1,
The power supply means operates based on a standby power supply, continuously measures an elapsed time after the ignition switch is turned off, and supplies the operating power when the measurement time reaches a predetermined time. A failure diagnosis device for a fuel vapor purge system, wherein The failure diagnosis device for a fuel vapor purge system according to claim 1 or 2,
The detection means is a pressure sensor for detecting a pressure in a fuel tank mounted on the vehicle;
The stationary determination means integrates the acceleration of pressure change in the fuel tank over a predetermined period, and determines that the vehicle is stationary based on the integrated value being less than a predetermined value. A failure diagnosis apparatus for a fuel vapor purge system . The failure diagnosis device for a fuel vapor purge system according to claim 1 or 2,
The detection means is a global positioning system that detects the position of the vehicle based on a position signal output by an artificial satellite,
The failure determination of the fuel vapor purge system, wherein the stationary determination means determines that the vehicle is stationary based on a change in the position of the vehicle during a predetermined period being less than a predetermined value. apparatus. The failure diagnosis device for a fuel vapor purge system according to claim 1 or 2,
The detection means is an acceleration sensor that detects acceleration acting on the vehicle based on movement of the vehicle,
The failure determination device for a fuel vapor purge system, wherein the stationary determination means determines that the vehicle is stationary based on the fact that the acceleration sensor detects that the acceleration is zero. . The failure diagnosis device for a fuel vapor purge system according to claim 1 or 2,
The detection means is a vehicle speed sensor that detects a vehicle speed of the vehicle,
The failure determination device for a fuel vapor purge system, wherein the stationary determination means determines that the vehicle is stationary based on the vehicle speed sensor detecting that the vehicle speed is zero. .

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