JP2007127065A - Electric pump control device and leak diagnosis device for evaporated fuel treatment system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a trouble of a pump function due to condensation of an electric air pump decompressing or compressing a closed space in an evaporated fuel treatment system after engine stop. <P>SOLUTION: ECU 10 controlling an operation condition of the electric air pump 2 of a leak check module 1 is constructed to cancel leak check in the closed space of the evaporated fuel treatment system when temperature difference ΔT between ambient temperature T1 measured by ambient temperature sensors 71, 72 and pump temperature T2 measured by a temperature sensor 73 other than the ambient temperature sensors is condensation judgment value (threshold value) or greater even after predetermined time passes after an ignition switch is turned off (IG/OFF) and engine operation is stopped. Consequently, trouble of pump function due to condensation of the electric air pump can be prevented and diagnosis accuracy of leak check in the closed space of the evaporated fuel treatment system can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric pump control device that controls an operation state of an electric pump incorporated in an engine control system or a vehicle control system, and in particular, using an electric air pump incorporated in an evaporative fuel treatment system, The present invention relates to a leak diagnosis apparatus for an evaporative fuel processing system that performs leak diagnosis in a closed space.

[Conventional technology]
Conventionally, evaporative fuel (also referred to as gasoline vapor or evaporation gas) volatilized in a fuel tank of a vehicle such as an automobile is supplied to the engine intake pipe via a canister and a purge VSV (vacuum switching valve). An evaporative fuel processing system that prevents the evaporative fuel from being released into the atmosphere by introducing (purging) using a gas is known. Here, in the evaporative fuel processing system, in order to prevent the evaporative fuel from leaking from the evaporative fuel processing system into the atmosphere (leakage), the leak that performs leak diagnosis of the evaporative fuel processing system is prevented. A diagnostic device is incorporated (see, for example, Patent Document 1).

  A leak diagnosis apparatus for an evaporative fuel processing system includes an electromagnetic valve that opens and closes an atmosphere opening hole of a canister, and an electric air pump such as a vane pump installed between a purge port and a purge VSV of the canister, and is predetermined after the engine is stopped. When the pump operating condition (leakage diagnosis execution condition) is satisfied, the purge VSV is fully closed, the atmosphere opening hole of the canister is closed by a solenoid valve, the electric air pump is operated, and the inside of the closed space of the evaporated fuel processing system is The leak diagnosis is performed in the closed space of the evaporated fuel processing system by reducing the pressure. Further, as a leak diagnosis apparatus for an evaporative fuel treatment system, a leak diagnosis apparatus in which a leak check module incorporating an electric air pump and a two-position switching valve is connected to the atmosphere opening hole of a canister of the evaporative fuel treatment system has been proposed (for example, , See Patent Document 2). Note that a vane pump used as an electric air pump has a rotor connected to a motor shaft of an electric motor, a plurality of vanes guided slidably in a plurality of guide grooves of the rotor, and a motor shaft. It is configured by an annular casing or the like that is fixed to the housing and accommodates the rotor rotatably.

  In addition, as shown in the flowchart of FIG. 5, the leak diagnosis apparatus described in Patent Documents 1 and 2 first determines whether or not the ignition switch is turned off (IG / OFF) (step S11), and the determination result. Is YES, that is, it is determined whether or not a precondition (leak diagnosis execution condition) for executing leak diagnosis after engine stop is satisfied (step S12). If the determination result is YES, a leak diagnosis (leak check) in the enclosed space of the evaporated fuel processing system is performed (step S13). If the determination result in step S12 is NO, the leak diagnosis ( It is configured to cancel (leak check) (step S14). In the prior art, if the ambient temperature measured by the engine coolant temperature sensor (or the engine intake air temperature sensor) used as the ambient temperature sensor after the engine is stopped is within a predetermined range, the leak diagnosis execution condition is It is determined that it has been established, and a leak diagnosis (leak check) in the enclosed space of the evaporated fuel processing system is performed.

[Conventional technical problems]
However, the leak diagnosis execution conditions described above simply set the threshold value within the temperature range that prevents freezing on the low temperature side and does not cause fuel boiling on the high temperature side, and considers the humidity environment when performing leak diagnosis. The current situation is not. Therefore, in the leak diagnosis method using an electric air pump, if there is a temperature difference between the air sucked into the electric air pump and the temperature of the electric air pump itself, warm air is sucked into the electric air pump and the dew point temperature When cooled below, moisture in the air condenses and water droplets adhere to the internal components of the electric air pump. That is, moisture in the air may condense inside the electric air pump, resulting in a malfunction in the pump function of the electric air pump. The malfunction of the pump function is caused by the fact that the surface tension due to moisture adhesion becomes larger than the centrifugal force at which the vane jumps out of the rotor due to moisture adhesion due to condensation, for example. As a result, the closed space of the evaporative fuel processing system cannot be sufficiently depressurized, causing a problem that the accuracy of leak diagnosis is reduced.
JP 2002-364465 A (page 1-9, FIG. 1 to FIG. 5) JP 2004-232521 (page 1-16, FIG. 2 to FIG. 9)

  An object of the present invention is to provide an electric pump control device that can prevent a malfunction of a pump function due to condensation of an electric pump that pressurizes and discharges air sucked inside after starting or stopping the engine. is there. It is another object of the present invention to provide a leak diagnosis apparatus for an evaporative fuel processing system that can prevent a malfunction of a pump function due to condensation of an electric air pump that depressurizes or pressurizes the closed space of the evaporative fuel processing system after the engine is stopped.

  According to the first aspect of the present invention, the electric pump is configured to start the operation of the electric pump incorporated in the engine control system or the vehicle control system when a predetermined pump operation condition is satisfied after the engine is started or after the engine is stopped. Is controlling the operating state. Even if other pump operating conditions are satisfied after the engine is stopped, the temperature difference between the ambient temperature estimated by the ambient temperature estimation means and the pump temperature estimated by the pump temperature estimation means is greater than or equal to the condensation determination value. In some cases, the operation of the electric pump is prohibited. Thereby, the malfunction of the pump function due to condensation of the electric pump can be prevented in advance. According to the second aspect of the present invention, it is possible to accurately determine a state where the electric pump is highly likely to condense by correcting the dew condensation determination value based on the atmospheric pressure detected by the pressure sensor. Can do. Further, according to the invention described in claim 3, a vane pump is used as the electric pump. In this case, it is possible to prevent the pump performance of the electric pump from deteriorating due to the vane sticking to the rotor due to adhesion of moisture due to condensation of the vane pump.

  According to the fourth aspect of the present invention, the operation state of the electric air pump is controlled so that the operation of the electric air pump incorporated in the evaporated fuel processing system is started when a predetermined pump operation condition is established after the engine is stopped. Yes. Even if other pump operating conditions (leak diagnosis execution conditions) are satisfied after the engine is stopped, the temperature difference between the ambient temperature estimated by the ambient temperature estimating means and the pump temperature estimated by the pump temperature estimating means is dew condensation determination. If it exceeds the value, operation of the electric air pump is prohibited. That is, when the temperature difference between the ambient temperature and the pump temperature is equal to or greater than the dew condensation determination value, for example, warm air is prevented from leak diagnosis in the enclosed space of the evaporative fuel processing system, so that warm air is ) In the vicinity, the water is cooled to a dew point temperature or less, moisture in the air is condensed, and water droplets can be prevented from adhering to the internal parts of the electric air pump. That is, the malfunction of the pump function due to condensation of the electric air pump can be prevented. Therefore, for example, the reliability of the leak diagnosis apparatus that performs leak diagnosis in the closed space of the evaporated fuel processing system can be ensured by using an electric air pump that pressurizes or depressurizes the closed space of the evaporated fuel processing system.

  According to the fifth aspect of the present invention, the operation state of the electric air pump is controlled so that the operation of the electric air pump incorporated in the evaporated fuel processing system is started when a predetermined pump operation condition is established after the engine is stopped. Yes. Even if other pump operating conditions (leak diagnosis execution conditions) are satisfied after the engine is stopped, the temperature difference between the ambient temperature estimated by the ambient temperature estimating means and the pump temperature estimated by the pump temperature estimating means is dew condensation determination. If it exceeds the value, operation of the electric air pump is prohibited. That is, when the temperature difference between the ambient temperature and the pump temperature is equal to or greater than the dew condensation determination value, the operation of the leak check module is prohibited, and the leak diagnosis in the enclosed space of the evaporated fuel processing system is prohibited, for example, warm. It is possible to prevent the air from being cooled below the dew point temperature in the vicinity of the internal components (components) of the electric air pump, moisture in the air condensing, and water droplets from adhering to the internal components of the electric air pump. That is, the malfunction of the pump function due to condensation of the electric air pump can be prevented. Therefore, the reliability of the leak diagnosis by the leak check module including the electric air pump can be ensured.

  According to the sixth aspect of the present invention, the electric air pump is covered with the electromagnetic valve together with the housing and integrated with the electromagnetic valve. Thereby, a leak check module is comprised by an electric air pump and a solenoid valve. According to the seventh aspect of the invention, there is a high possibility that the electric air pump (or the electromagnetic valve or the housing) is condensed by correcting the condensation determination value based on the atmospheric pressure detected by the pressure sensor. The state can be determined with high accuracy. Further, according to the invention described in claim 8, a vane pump is used as the electric air pump. In this case, it is possible to prevent the pump performance of the electric air pump from deteriorating due to the vane sticking to the rotor due to the adhesion of moisture due to condensation of the vane pump.

  The best mode for carrying out the present invention is to prevent the malfunction of the pump function due to condensation of the electric pump in advance, and to estimate the ambient temperature estimated by the ambient temperature estimation means and the pump estimated by the pump temperature estimation means This was realized by prohibiting the operation of the electric pump when the temperature difference from the temperature was greater than the condensation judgment value. In addition, in order to prevent a malfunction of the pump function due to condensation of the electric air pump, the temperature difference between the ambient temperature estimated by the ambient temperature estimation means and the pump temperature estimated by the pump temperature estimation means is equal to or greater than the condensation determination value. In this case, it was realized by prohibiting leak diagnosis in the enclosed space of the evaporative fuel treatment system.

[Configuration of Example 1]
1 to 4 show a first embodiment of the present invention. FIG. 1 is a diagram showing an overall configuration of an evaporative fuel processing system, and FIG. 2 is a diagram showing an overall structure of a leak check module.

  The leak check module 1 according to the present embodiment includes a fluid (gasoline vapor) such as an evaporated fuel that evaporates and volatilizes in a fuel tank 11 of a vehicle such as an automobile equipped with an internal combustion engine (hereinafter referred to as an engine) such as a gasoline engine. (Also referred to as evaporation gas) via a canister 12 and a purge VSV (vacuum switching valve) 13 into the engine intake pipe 14 of the engine communicating with the combustion chamber of each cylinder of the engine (purging) It is incorporated in an evaporative fuel processing system (evaporative fuel transpiration prevention device) that prevents evaporative fuel from being released into the atmosphere.

  This evaporative fuel processing system is one of the components of an engine control system mounted on a vehicle such as an automobile, and the fuel tank 11 and the evaporation gas port (tank side port) of the canister 12 are connected to a fluid flow channel pipe ( The purge port of the canister 12 and the engine intake pipe 14 communicate with each other via a fluid flow path pipe (second air flow path pipe) 16. An air passage (purge passage, fluid passage) for guiding a fluid such as evaporated fuel volatilized in the fuel tank 11 to the canister 12 is formed in the first air passage pipe 15. An air flow path (purge passage, fluid flow path) for guiding fluid such as evaporated fuel adsorbed by the canister 12 to the engine intake pipe 14 via the purge VSV 13 is provided in the second air flow path pipe 16. Is formed.

  In the canister 12, an adsorbent (for example, activated carbon or the like) that adsorbs a fluid such as evaporated fuel is accommodated. The downstream end of the air release pipe (air flow pipe) 17 in the air flow direction is connected to the atmosphere release hole (air inlet port) of the canister 12. The leak check module 1 is connected to the upstream end of the air release pipe 17 in the air flow direction. An air flow path (fluid flow path) for guiding an air flow generated by introducing the intake pipe negative pressure into the leak check module 1 to the canister 12 is formed in the atmosphere opening pipe 17. . Further, the purge VSV 13 is installed in the middle of the second air flow path pipe 16 and the evaporation desorbed from the adsorbent in the canister 12 by controlling the energization time to the solenoid coil of the purge VSV 13 by the engine control unit. This is a purge control valve (purge control valve) for controlling the purge flow rate for introducing a fluid containing fuel into the engine intake pipe 14. A throttle valve 19 for adjusting the amount of intake air taken into the combustion chamber of each cylinder of the engine is rotatably accommodated in the engine intake pipe 14.

  The leak check module 1 of this embodiment includes a vane type electric air pump 2, an electric motor 3 that is a power source of the electric air pump 2, an electromagnetic valve 4 having a two-position three-way switching valve, A solenoid coil 5 that is a power source, a check valve 6 that is opened by a pumping operation of the electric air pump 2, an orifice plate 7 in which a reference orifice (described later) is formed, and a pressure that measures the pressure inside the housing The sensor 9 is constituted. These are covered with a housing constituted by four cases (first to fourth cases 21 to 24), and the first to fourth cases 21 to 24 are coupled with fastening screws, clips, locking pieces, and the like. Has been.

  The electric air pump 2 includes an electric motor 3 that is driven by electric power, and a vane pump (pump main body) that is rotationally driven by a rotational motion of a motor shaft (rotor shaft) 25 of the electric motor 3. The electric motor 3 is accommodated in the housing. In this embodiment, a brushless direct current (DC) motor is employed as the electric motor 3. Instead of the brushless DC motor, a direct current (DC) motor with a brush or an alternating current (AC) motor such as a three-phase induction motor may be used.

  The vane pump includes a rotor 26 coupled to the motor shaft 25 of the electric motor 3, a plurality of vanes 27 slidably guided in a plurality of guide grooves (not shown) of the rotor 26, and a motor shaft 25. On the other hand, it is constituted by an annular casing 30 or the like which is eccentrically fixed to a housing 28 composed of a block, a plate and the like by a screw 29. An air suction port and an air discharge port are formed in the housing 28 of the electric air pump 2. In addition, a circular space (pump chamber) that rotatably accommodates the rotor 26 together with the plurality of vanes 27 is formed in the casing 30. Here, the air suction port of the electric air pump 2 communicates with the internal space (air flow path 31) formed inside the first case 21 via the check valve 6. The air discharge port of the electric air pump 2 is open to the atmosphere via an outlet tube 32 coupled to the housing (first case 21). The outlet tube 32 is formed with an air discharge port (atmosphere release hole) 33 for discharging a fluid such as air from the pump chamber of the electric air pump 2.

  The electromagnetic valve 4 is covered with a housing (first to third cases 21 to 23) together with the electric air pump 2. The electromagnetic valve 4 has a two-position three-way switching valve that is driven to two positions by an electromagnetic drive unit (solenoid unit). The electromagnetic drive unit is an electromagnetic actuator that generates a magnetic attractive force (magnetomotive force) by supplying an excitation current. The electromagnetic coil 5 generates a magnetic flux when energized, and is excited by the solenoid coil 5. The fixed core such as the stator core 34 and the yoke 35, and the moving core (movable core, movable portion) 36 that forms a magnetic circuit together with the solenoid coil 5, the stator core 34, and the yoke 35 are configured.

  Further, the solenoid coil 5 has a coil portion in which a conductive wire having a resin insulating coating on its surface is wound around the coil bobbin 37 a plurality of times, and a pair of terminal lead wires taken out from the coil portion. . Further, between the stator core 34 and the moving core 36, a two-position three-way switching valve and a coil spring 38 that urges the moving core 36 in the fully closing direction of the electromagnetic valve 4 are mounted. Further, the axial end of the two-position three-way switching valve is inserted into the moving core 36, and the valve side and the electromagnetic drive unit side are assembled on the outer periphery of the two-position three-way switching valve. The diaphragm 39 is airtightly partitioned.

  The two-position three-way switching valve has two first and second fluid passage ports (hereinafter referred to as first and second fluid passage ports) disposed opposite to each other with a predetermined gap inside the housing (first and second cases 21 and 22). First and second valves 45 and 46 that selectively open and close 41 and 42, and valves that linearly move in the axial direction integrally with the first and second valves 45 and 46. This is a movable member constituted by a shaft 47. The first valve 45 is always pressed against the lower end of the valve shaft 47 by the urging force (spring force) of the coil spring 49.

  Here, the 1st-4th cases 21-24 which comprise a housing comprise the pump housing which accommodates the electric air pump 2 inside. The first and fourth cases 21 and 24 constitute a motor housing that houses the electric motor 3 therein. Moreover, the 2nd case 22 comprises the cylindrical valve case which accommodates the 2 position 3 direction switching valve of the solenoid valve 4 inside so that opening and closing is possible. Further, the first to third cases 21 to 23 constitute an actuator case that accommodates the electromagnetic drive unit of the electromagnetic valve 4 therein.

  And the 1st case 21 has the cylindrical part 51 which fits the 2nd case 22 airtightly. The canister port side end portion of the first case 21 has a double-pipe structure including a cylindrical portion 51 and a cylindrical portion 52 disposed on the inner diameter side in the radial direction with respect to the cylindrical portion 51. An air channel (fluid channel) 53 is formed between the inner peripheral surface of the cylindrical portion 51 and the outer peripheral surface of the cylindrical portion 52. An air flow path (fluid flow path) 31 is formed inside the cylindrical portion 52. The air flow path 31 communicates with the air suction port of the electric air pump 2 via the air flow path (fluid flow path) 54 and the check valve 6. The air flow path 54 is connected to the air flow path 31 in a T shape and extends toward the outer diameter side of the air flow path 31 in the radial direction, and is formed integrally with the cylindrical portion 52. An air channel tube (fluid channel tube) 55 is formed inside.

  Further, at the opening end of the cylindrical portion 52 on the lower end side in the figure, a canister port (a housing first port) that communicates with the atmosphere opening hole (air inlet port) of the canister 12 through an air passage formed in the atmosphere opening pipe 17. 3 fluid port: hereinafter referred to as a third fluid port) 43 is formed. A first valve seat on which the first valve 45 is pressed by the spring force of the coil spring 38 is provided on the upper end surface of the cylindrical portion 52 of the first case 21 in the figure. A first fluid port (first fluid port of the housing) 41 is formed inside the first valve seat as a valve port that opens at the upper end of the cylindrical portion 52 in the figure and is closed by the first valve 45. Yes. Further, an annular second valve seat on which the second valve 46 is seated is provided on the inner peripheral portion of the second case 22 as necessary. Inside the second valve seat, a second fluid port (second fluid port of the housing) 42 serving as a valve port is formed.

  In addition, an air duct 59 for sending air (air) into the internal space (diaphragm storage chamber 56 and valve storage chamber 57) of the second case 22 is provided at a side portion of the cylindrical portion 51 of the first case 21. It is integrally formed. Further, the air duct 59 is formed with an air suction port (an inlet portion of the first case 21, an air opening hole) 61 for sucking air into the internal space (air flow path 60) of the air duct 59. Note that an air filter 62 for filtering air flowing into the canister 12 may be provided in the middle of the air duct 59 (see FIG. 1). The air filter 62 can pass air flowing in from the air suction port 61 of the air duct 59, but captures foreign matter mixed in the air and introduces foreign matter into the leak check module 1, the canister 12 and the engine intake pipe 14. Is to prevent intrusion. In addition, the second case 22 has a communication path (fourth fluid port of the housing: hereinafter) that communicates the air flow path 60 of the air duct 59 and the internal space (the diaphragm housing chamber 56 and the valve housing chamber 57) of the second case 22. 44) (referred to as the fourth fluid port).

  A circular pipe joint 63 that is airtightly coupled to the canister-side air release pipe 17 is integrally formed on the canister side of the first case 21. This pipe joint 63 is connected to the internal space (air flow path 31 or air flow path 53) of the first case 21 and the air release hole (air) of the canister 12 via an air flow path formed in the air release pipe 17. A canister port (canister side port of the housing) 64 communicating with the inlet port) is formed. The canister port 64 is used for introducing the atmosphere (air) sucked from the air suction port 61 of the air duct 59 into the canister 12 from the inside of the leak check module 1 during the purge operation using the intake pipe negative pressure in the evaporated fuel processing system. In addition, the leak check module 1 uses the pump operation of the electric air pump 2 to discharge air (air) in the closed space of the evaporative fuel processing system at the time of leak check in the closed space of the evaporative fuel processing system. It functions as an air suction port for sucking into the interior of the air.

  The check valve 6 includes a cylindrical valve case 65 disposed between a downstream side of the air flow channel 55 of the first case 21 in the air flow direction and an air suction port of the housing 28 of the electric air pump 2. A valve seat 66 that is held and fixed to the inner peripheral portion of the valve case 65 in the middle of the axial direction of the case 65, a ball valve (valve element) that opens and closes a valve port formed inside the valve seat 66, and a ball valve On the other hand, it is constituted by a coil spring 67 or the like that urges the ball valve in a direction in which the ball valve is pressed against the valve seat (opening peripheral portion of the valve port) 66 (direction in which the valve port is closed). The check valve 6 has a check valve function for preventing air (air) from flowing backward from the electric air pump side to the air flow path side (solenoid valve side). A plate 68 having a communication hole (not shown) is disposed at the upstream opening end of the valve case 65 in the air flow direction, and the downstream opening end of the valve case in the air flow direction. A spring seat 69 in which a communication hole is formed is disposed.

  The orifice plate 7 is held and fixed inside the canister side of the cylindrical portion 52 of the first case 21 while being sandwiched between orifice stoppers. On the central axis of the orifice plate 7, the flow path cross-sectional areas of the first and third fluid ports 41 and 43 formed at the opening ends on both sides in the axial direction of the cylindrical portion 52 and the cylindrical portion 52 are formed. A reference orifice 70 having a channel cross-sectional area extremely smaller than the channel cross-sectional area of the air channel 31 is formed. Here, the reference orifice 70 is a reference hole provided in the orifice plate 7 for measuring a reference pressure used for leak diagnosis (fuel leak determination) in the closed section of the evaporated fuel processing system.

  Here, the evaporative fuel processing system of the present embodiment is based on the operating state of the engine, the electric motor 3 that is the power source of the electric air pump 2, the solenoid coil 5 that is the power source of the electromagnetic valve 4, and the power source of the purge VSV 13. An engine control unit (hereinafter referred to as ECU) 10 for electronically controlling the actuator (solenoid coil) is provided. The ECU 10 includes functions such as a CPU that performs control processing and arithmetic processing, a storage device that stores various programs and data (a non-volatile memory such as an EEPROM, and a volatile memory such as a ROM / RAM). A microcomputer having a known structure is provided. Then, when the ignition switch is turned on (IG / ON) and the engine starts operation, the ECU 10 controls the electric air pump 2, the electromagnetic valve 4, and the purge VSV 13 based on a control program stored in the volatile memory. To do. Note that the ECU 10 controls the energization time (ratio of on time to off time: duty ratio) to the solenoid coil of the purge VSV 13, for example, so that fluid including fluid such as evaporated fuel is sent from the canister 12 to the engine intake pipe 14. The purge flow rate introduced into the inside is controlled.

  Then, the ECU 10 A / D-converts sensor signals and switch signals from various switches installed in a vehicle such as an automobile and the like, and then inputs them to a microcomputer built in the ECU 10. It is configured as follows. The microcomputer input circuit includes a crank angle sensor for detecting the rotation angle (crank angle) of the crankshaft of the engine, and an accelerator opening sensor for detecting the depression amount (accelerator opening) of the driver's accelerator pedal. Various sensors such as a throttle opening sensor for detecting the opening of the throttle valve 19 (throttle opening) and an intake pressure sensor for detecting the intake pipe negative pressure are connected.

  Further, an outside air temperature that converts the outside air temperature (outside air temperature) of a vehicle such as an automobile into an electrical signal (outside air temperature signal) and outputs how much the outside air temperature has changed is output to the microcomputer 10 as an input circuit. A sensor 71 is connected. Also, the microcomputer's input circuit converts the intake air temperature (intake air temperature) drawn into the engine cylinders into an electrical signal (intake air temperature signal) and outputs to the ECU 10 how much the engine intake air temperature has changed. An engine intake air temperature sensor 72 is connected. Further, an engine cooling water temperature sensor 73 that converts the engine temperature (for example, engine cooling water temperature) into an electrical signal (cooling water temperature signal) and outputs to the ECU 10 how much the engine cooling water temperature has changed is output to an input circuit of the microcomputer. Is connected.

  Further, a pressure sensor 9 for converting the pressure in a predetermined closed section of the evaporated fuel processing system into an electrical signal (pressure signal) and outputting how much the pressure has changed is connected to the input circuit of the microcomputer. Has been. The pressure sensor 9 is introduced from sensing ports (pressure measurement holes communicating with the air flow path 54 of the first case 21) 74 to 76 provided in the first, third, and fourth cases 21, 23, and 24. It is a pressure detection means which detects the internal pressure (pressure in the air flow path 54) of the leak check module 1. A pressure sensor (tank internal pressure sensor) for detecting the pressure in the fuel tank 11 (tank internal pressure) may be installed in the fuel tank 11.

  In addition, the ECU 10 stores the predetermined leak diagnosis execution condition (pump operation condition) in the memory after the ignition switch is turned off (IG / OFF) and the engine stops operating (after the engine stops). The electric air pump 2, the solenoid valve 4 and the purge VSV 13 are controlled based on the stored control program. ECU10 comprises the pump control unit which adjusts the electric power supplied especially to the electric motor 3, and controls the driving | running state (rotation motion: for example, a rotational speed or a rotation direction) of the electric air pump 2. FIG. Thereby, even after the engine is stopped, it is possible to perform a leak check in the closed section of the evaporated fuel processing system. Here, for a while after the engine is stopped, the pressure in the evaporative fuel treatment system increases due to the evaporative fuel generated in the fuel tank 11, and then the engine temperature decreases or the fuel temperature in the fuel tank 11 decreases. Along with this, the pressure in the evaporated fuel processing system decreases. Further, immediately after the engine is stopped, the fuel filler cap of the fuel tank 11 is opened for fuel supply, and the pressure in the evaporated fuel processing system may change.

  Therefore, in order to ensure the diagnostic accuracy of the leak check after engine stop, in order not to be affected by the change in evaporated fuel generation amount after engine stop and the pressure change in the evaporated fuel processing system due to the opening of the fuel filler port, After a predetermined time (for example, 5 hours, 7 hours, 9 hours, etc.) has elapsed after the engine is stopped, it is desirable to perform a leak check in the closed section of the evaporated fuel processing system. For this reason, in the present embodiment, the first condition of the leakage diagnosis execution condition is established when a predetermined time has elapsed after the ignition switch is turned off (IG · OFF) and the engine is stopped.

  In addition, if the ambient temperature around the evaporative fuel processing system, particularly the leak check module 1 and the fuel tank 11, is within the specified range, it is possible to prevent freezing on the low temperature side and to prevent fuel boiling on the high temperature side. Become. For this reason, the ECU 10 has an ambient temperature estimation means for estimating (calculating) the ambient temperature (T1) based on the electrical signal output from the “atmosphere temperature sensor” after the first condition of the leak diagnosis execution condition is established. is doing. Next, the second condition of the leak diagnosis execution condition is established when the atmospheric temperature (T1) measured by the “atmospheric temperature sensor” is within a specified range. As the “atmosphere temperature sensor”, it is desirable to use, for example, an outside air temperature sensor 71 that reacts relatively sensitively to the outside air temperature. Further, the engine intake air temperature sensor 72 or the like may be used as the atmospheric temperature sensor.

  Further, the ECU 10 has a pump temperature estimating means for estimating (calculating) the internal temperature of the electric air pump 2 based on an electric signal output from the “temperature sensor other than the ambient temperature sensor”. The temperature difference (ΔT) between the ambient temperature (T1) measured by the “atmosphere temperature sensor” and the pump temperature (T2) measured by the “temperature sensor other than the ambient temperature sensor” is equal to or greater than the condensation determination value (threshold). When the value is too large, the leak check is canceled to prevent the malfunction of the electric air pump 2 due to condensation. Conversely, the third condition of the leakage diagnosis execution condition is established when the temperature difference (ΔT) is smaller than the dew condensation determination value (threshold value) and it can be determined that there is no dew condensation. The “temperature sensor other than the ambient temperature sensor” is relatively insensitive to changes in the outside air temperature, which can ensure a temperature difference from the ambient temperature (T1) measured by the “ambient temperature sensor”. It is desirable to use a temperature sensor. As the “temperature sensor other than the ambient temperature sensor”, for example, an engine cooling water temperature sensor 73, a vehicle interior air temperature (inside air temperature) sensor or the like may be used, and a fuel temperature sensor that measures the fuel temperature in the fuel tank 11. May be used.

In addition, the determination of the magnitude (ΔT) of the temperature difference (ΔT) between the atmospheric temperature (T1) measured by the “atmosphere temperature sensor” and the pump temperature (T2) measured by the “temperature sensor other than the atmospheric temperature sensor”, in other words, leakage. It is desirable to determine the dew condensation determination value (threshold value) for checking or canceling by a two-dimensional map (see FIG. 3) or an arithmetic expression created by measurement in advance through experiments or the like. Note that different maps are used for the two-dimensional map depending on the temperature detected by the “temperature sensor other than the ambient temperature sensor”. Here, since the pressure sensor 9 is installed in the leak check module 1, the condensation determination value (threshold value) of the two-dimensional map (see FIG. 3) is corrected by measuring the atmospheric pressure with the pressure sensor 9. You may do it.

[Control Method of Example 1]
Next, a control method of the evaporated fuel processing system of the present embodiment will be briefly described with reference to FIGS. Here, FIG. 4 is a flowchart showing a method for determining whether or not to perform a leak check in the closed section of the evaporated fuel processing system. The control routine of FIG. 4 is executed at predetermined timings after the ignition switch is turned on (IG / ON).

First, it is determined whether or not the ignition switch is turned off (IG · OFF) from on (IG · ON) (step S1). If the determination result is NO, that is, if the engine is operating, the control routine of FIG. 4 is exited.
If the determination result in step S1 is YES, that is, if the engine operation is stopped, it is determined whether or not a predetermined time (for example, 5 hours) has elapsed since the engine stopped (step S2). If the determination result is NO, the leak check in the closed section of the evaporated fuel processing system is canceled (leak diagnosis prohibiting means: step S3). Thereafter, the control routine of FIG. 4 is exited.

  If the determination result in step S2 is YES, that is, if a predetermined time has elapsed after the engine is stopped, the ambient temperature (T1) measured by the “atmosphere temperature sensor” is read and a nonvolatile memory such as an EEPROM is read. (Atmosphere temperature estimation means: step S4). Next, it is determined whether or not the atmospheric temperature (T1) measured by the “atmospheric temperature sensor” is within a specified range (step S5). If the determination result is NO, that is, if the atmospheric temperature (T1) is not within the specified range, the process proceeds to step S3. That is, the leak check in the closed section of the evaporated fuel processing system is cancelled.

  If the determination result in step S5 is YES, that is, if the ambient temperature (T1) is within the specified range, the pump temperature (T2) measured by the “temperature sensor other than the ambient temperature sensor” is read, and the EEPROM Or the like (pump temperature estimation means: step S6). Next, a temperature difference (ΔT) between the ambient temperature (T1) and the pump temperature (T2) is detected (calculated) (step S7). Next, based on the two-dimensional map shown in FIG. 3, it is determined whether or not the temperature difference (ΔT) between the atmospheric temperature (T1) and the pump temperature (T2) is greater than the dew condensation determination value (threshold value) ( Condensation determination means: Step S8). If this determination result is NO, that is, if the temperature difference (ΔT) is smaller than the dew condensation determination value (threshold value), a leak check is performed in the closed section of the evaporated fuel processing system (leak diagnosis execution means: step S9). ). Thereafter, the control routine of FIG. 4 is exited.

  If the determination result in step S8 is YES, that is, if the temperature difference (ΔT) is greater than or equal to the dew condensation determination value (threshold value), the process proceeds to step S3. That is, the leak check in the closed section of the evaporated fuel processing system is cancelled. Here, when the leak check is cancelled, the control routine of FIG. 4 may be executed every time a certain time elapses. That is, the leak check in the closed section of the fuel vapor processing system may be retried.

[Operation of Example 1]
Next, the operation of the evaporated fuel processing system of this embodiment will be briefly described with reference to FIGS.

B) A purge operation using the intake pipe negative pressure will be described with reference to FIGS.
During operation of the engine, for example, when the intake pipe negative pressure (intake pressure) detected by the intake pressure sensor is higher than a predetermined value, the ECU 10 first applies the solenoid coil of the purge VSV 13 so that the purge VSV 13 is opened. Supply power. At this time, since electric power is not supplied to the electric motor 3 of the electric air pump 2 and the solenoid coil 5 of the electromagnetic valve 4, the electric air pump 2 does not perform the pump operation, but the two-position three-way switching valve of the electromagnetic valve 4 is Since the first valve 45 is pressed against the first valve seat of the first case 21 by the biasing force of the coil spring 38, the two-position three-way switching valve of the electromagnetic valve 4 continues to be closed. That is, the first fluid port 41 is closed by the first valve 45, and the second fluid port 42 is opened by the second valve 46. In this case, the air suction port 61 of the air duct 59 and the canister port 64 of the first case 21 are in communication with each other via the second fluid port 42 (see FIG. 2).

  Therefore, when the engine intake pipe negative pressure reaches the inside of the housing (first and second cases 21, 22) of the leak check module 1, the air flow path 60 → the fourth fluid port 44 from the air inlet 61 of the air duct 59. → diaphragm storage chamber 56 → second fluid port 42 → valve storage chamber 57 → air flow path 53 → canister port 64 → air flow toward the air release pipe 17 and further from the air inlet port (atmosphere release hole) of the canister 12 There is an air flow toward the purge port. When such an air flow is generated, desorption occurs in the evaporated fuel adsorbed by the adsorbent in the canister 12, and the evaporated fuel desorbed from the adsorbent flows out of the purge port of the canister 12 to generate the second air. It is introduced (purged) into the combustion chamber of the engine via the flow path pipe 16 → purge VSV 13 → engine intake pipe 14 → intake port.

B) Next, a method of performing a leak check in the closed space of the fuel vapor processing system will be described with reference to FIGS.
After the ignition switch is turned off (IG / OFF), the ECU 10 performs a leak in the closed space of the evaporative fuel processing system when all the conditions (first to third conditions) of the leak diagnosis execution conditions are satisfied. Check. This can be implemented when the power supply to the microcomputer is continued even after the ignition switch is turned off (IG • OFF).

  When all the conditions (first to third conditions) of the leak diagnosis execution condition are satisfied after the engine is stopped, the ECU 10 first continues the closed state of the two-position three-way switching valve of the solenoid valve 4 and the purge VSV 13. At this time, since the second fluid port 42 is opened in the sensing ports 74 to 76 of the pressure sensor 9, the air suction port 61 and the air flow path 60 of the air duct 59, the fourth fluid port 44, the diaphragm housing chamber 56, The second fluid port 42, the valve accommodating chamber 57, the air channel 53, the canister port 64, the third fluid port 43, the reference orifice 70 of the orifice plate 7, the air channel 31, and the air channel 54 communicate with each other. . For this reason, since the internal pressure of the leak check module 1 (pressure in the air flow path 54) is equivalent to atmospheric pressure, the detection value of the pressure sensor 9 is a pressure value corresponding to atmospheric pressure. Therefore, the atmospheric pressure can be measured using the pressure sensor 9, and the atmospheric pressure measured by the pressure sensor 9 is stored in a nonvolatile memory such as an EEPROM. Note that when the atmospheric pressure is measured using the pressure sensor 9, the solenoid valve 4 is configured such that power is supplied to the solenoid coil 5 of the solenoid valve 4 to open both the first and second fluid ports 41 and 42. The first and second valves 45 and 46 may be held at an intermediate position of the valve housing chamber 57 of the second case 22.

  Next, the ECU 10 supplies power to the solenoid coil 5 of the solenoid valve 4 so that the two-position three-way switching valve of the solenoid valve 4 is opened while the purge VSV 13 is kept closed. As a result, an attractive magnetomotive force is generated in the solenoid coil 5 and the stator core 34, the yoke 35, and the moving core 36 are magnetized. Therefore, the two-position three-way switching valve and the moving core 36 are attracted to the stator core side (the upper side in the drawing). The And since the 2nd valve 46 of the solenoid valve 4 is pressed against the 2nd valve seat of the 2nd case 22, the 2 position 3 direction switching valve of the solenoid valve 4 will be in a valve opening state. That is, the first fluid port 41 is opened by the first valve 45 and the second fluid port 42 is closed by the second valve 46. In this case, the canister port 64 of the first case 21 and the air flow paths 31 and 54 of the first case 21 are in communication with each other via the first fluid port 41.

  As described above, when the two-position / three-way switching valve of the solenoid valve 4 is opened, the pressure sensor 9 is used to measure the internal pressure of the leak check module 1 (pressure in the air flow path 54), and the fuel. The volatilization state of the fuel (gasoline) in the tank 11 is checked. For example, if the fuel in the fuel tank 11 is evaporated, the internal pressure in the closed space of the evaporated fuel processing system becomes higher than the atmospheric pressure. After the pressure check, the 2-position 3-way switching valve of the solenoid valve 4 is closed again to close the 2-position 3-way switching valve of the solenoid valve 4. During the above operation, power is not supplied to the electric motor 3 of the electric air pump 2 and the solenoid coil of the purge VSV 13.

  Next, the ECU 10 starts the operation of the electric air pump 2 by supplying electric power to the electric motor 3 in a state where the two-position / three-way switching valve of the electromagnetic valve 4 and the purge VSV 13 are closed. Here, when the rotor 26 of the vane pump is driven to rotate by the rotational movement of the motor shaft 25 of the electric motor 3, the rotor 26 starts to rotate relative to the housing 28 and the casing 30. The air (air) inside the pump chamber is compressed by the movement (infestation operation and rotation operation). At this time, negative pressure is generated at the air suction port of the electric air pump 2, and high pressure is generated at the air discharge port of the electric air pump 2.

  Thereby, the atmosphere (air) sucked from the air inlet 61 of the air duct 59 is the air flow path 60 → the fourth fluid port 44 → the diaphragm storage chamber 56 → the second fluid port 42 → the valve storage chamber 57 → the air flow path. 53 → canister port 64 → third fluid port 43 → reference orifice 70 of orifice plate 7 → air flow path 31 → air flow path 54, then guided to check valve 6. As a result, the ball valve of the check valve 6 is lifted from the valve seat 66 against the urging force of the coil spring 67, so that the ball valve of the check valve 6 is opened. The atmospheric air (air) is guided to the air suction port of the electric air pump 2. The air (air) pressurized in the pump chamber of the electric air pump 2 is discharged from the air discharge port of the electric air pump 2 and discharged from the air discharge port 33 toward the atmosphere via the outlet tube 32. The

  Next, in this state, the ECU 10 measures the internal pressure of the leak check module 1 (pressure in the air flow path 54) using the pressure sensor 9, and sets the reference orifice 70 having a throttle diameter of, for example, about φ0.45 mm. A corresponding reference pressure (Pref) is detected, and this reference pressure (Pref) is stored in a nonvolatile memory such as an EEPROM. Next, the ECU 10 stops the supply of electric power to the electric motor 3 and temporarily stops the operation of the electric air pump 2. Next, the ECU 10 supplies power to the solenoid coil 5 of the solenoid valve 4 so that the two-position three-way switching valve of the solenoid valve 4 is opened while the purge VSV 13 is kept closed. And ECU10 will supply electric power to the electric motor 3, and will restart the driving | operation of the electric air pump 2, if the 2 position 3 direction switching valve of the solenoid valve 4 will be in a valve opening state.

  Here, when the rotor 26 of the vane pump is driven to rotate by the rotational movement of the motor shaft 25 of the electric motor 3, negative pressure is generated at the air suction port of the electric air pump 2, so that the canister port 64 of the first case 21. The air sucked from the air is guided to the check valve 6 via the air flow path 53 → the valve housing chamber 57 → the first fluid port 41 → the air flow path 31 → the air flow path 54. As a result, the ball valve of the check valve 6 is opened, so that air sucked from the canister port 64 of the first case 21 is guided to the air intake port of the electric air pump 2. Further, since a high pressure is generated at the air discharge port of the electric air pump 2, the air (air) pressurized in the pump chamber of the electric air pump 2 is discharged from the air discharge port of the electric air pump 2, and the outlet tube 32 is discharged. Then, the air is discharged from the air discharge port 33 toward the atmosphere. As a result, the internal pressure in the enclosed space of the fuel vapor processing system is reduced.

  Next, in this state, the ECU 10 uses the pressure sensor 9 to measure the internal pressure of the leak check module 1 (pressure in the air flow path 54: P) and stores the reference pressure stored in a nonvolatile memory such as an EEPROM. A leak diagnosis is performed by comparing (Pref) and the internal pressure (P) of the leak check module 1. Here, the ECU 10 determines that there is no fuel leakage when P <Pref, and that there is fuel leakage when P ≧ Pref. When it is determined that there is a fuel leak, a warning lamp (visual display means) such as a warning lamp is turned on, or an aural display means such as a buzzer or sound is operated to alert the driver.

  Thereafter, with the purge VSV 13 kept in the closed state, the two-position three-way switching valve of the electromagnetic valve 4 is closed, the supply of electric power to the electric motor 3 is stopped, and the operation of the electric air pump 2 is stopped. . This completes the leak check in the closed space of the evaporated fuel processing system. Here, the closed space of the evaporative fuel processing system refers to the space from the fuel tank 11 to the purge VSV 13 via the first air passage pipe 15, the canister 12 and the second air passage pipe 16 when the purge VSV 13 is closed. The purge VSV 13 includes a closed space and a closed space from the canister side of the second fluid port 42 of the leak check module 1 to the purge VSV 13 through the air release pipe 17, the canister 12 and the second air flow pipe 16. It is a space on the upstream side in the air flow direction.

[Effect of Example 1]
As described above, the ECU 10 of the evaporative fuel processing system can perform the predetermined time after the engine stops even when the first and second conditions among the leak diagnosis execution conditions are satisfied after the engine is stopped. Even if the ambient temperature (T1) measured by the “atmosphere temperature sensor” is within the specified range, if the third condition of the leak diagnosis execution condition is not satisfied, that is, the “atmosphere temperature sensor” When the temperature difference (ΔT) between the atmospheric temperature (T1) measured by “and the pump temperature (T2) measured by the“ temperature sensor other than the atmospheric temperature sensor ”is larger than the dew condensation determination value (threshold), The leak check in the enclosed space of the evaporative fuel processing system is configured to cancel.

  Therefore, when the temperature difference (ΔT) between the ambient temperature (T1) and the pump temperature (T2) is larger than the dew condensation determination value (threshold value), power is not supplied to the electric motor 3, and the electric air pump 2 The state where is turned off is continued. Thus, when the temperature difference (ΔT) between the ambient temperature (T1) and the pump temperature (T2) is larger than the dew condensation determination value (threshold value), a leak check is performed in the enclosed space of the evaporative fuel treatment system, and the air duct When warm air sucked from the air inlet 61 of the air 59 is sucked into the pump chamber of the electric air pump 2 through the first and second cases 21 and 22, the air is cooled by the components of the electric air pump 2. Thus, it is possible to prevent water droplets from adhering to the components of the electric air pump 2.

  That is, when the temperature difference (ΔT) between the ambient temperature (T1) and the pump temperature (T2) is larger than the dew condensation determination value (threshold), the leak check in the enclosed space of the evaporated fuel processing system is cancelled. Since the malfunction of the pump function due to condensation of the electric air pump 2 can be prevented in advance, for example, due to the adhesion of moisture due to condensation, the surface tension due to moisture adhesion becomes larger than the centrifugal force where the vane 27 jumps out of the rotor 26. There is nothing. Thereby, it is possible to sufficiently depressurize the enclosed space of the evaporated fuel processing system, and it is possible to improve the diagnostic accuracy of the leak check in the enclosed space of the evaporated fuel processing system.

[Modification]
In the present embodiment, the electric power supplied to the electric motor 3 is adjusted, the rotor 26 of the electric air pump 2 is rotated, the air sucked into the pump chamber from the air suction port is pressurized and discharged from the air discharge port. The enclosed space of the evaporative fuel processing system is depressurized (decreased), but the electric power supplied to the electric motor 3 is adjusted to rotate the rotor 26 of the electric air pump 2 so that the air is taken into the pump chamber from the air suction port. The inside of the closed space of the evaporated fuel processing system may be pressurized (high pressure) by pressurizing the sucked air and discharging it from the air discharge port.

  In the present embodiment, the example in which the electric pump of the present invention is applied to the electric air pump 2 incorporated in the evaporative fuel processing system has been described. However, the electric pump of the present invention is, for example, an exhaust purification system, a secondary air supply system, or the like. You may apply to the electric pump (for example, electric air pump etc.) incorporated in vehicle control systems, such as an engine control system or a suspension control system.

  Moreover, you may use the electric air pump 2 integrated in an evaporative fuel processing system as a purge pump. In this case, the operating state of the electric air pump 2 is controlled by adjusting the electric power supplied to the electric motor 3 during engine operation after engine startup. For example, during the purge operation, the electric motor 3 is rotated in the forward direction to pressurize the evaporative fuel processing system, and during the leak check, the electric motor 3 is rotated in the forward direction and the reverse direction to add to the evaporative fuel processing system. The pressure may be reduced or reduced.

  In this embodiment, the leak diagnosis execution condition is determined in the order of the first condition, the second condition, and the third condition, but may be performed in the order of the third condition, the first condition, and the second condition. Also, the third condition, the second condition, and the first condition may be performed in this order, or the first condition, the third condition, and the second condition may be performed in this order, and the second condition, the second condition, You may implement in order of 3 conditions and 1st condition, and you may implement in order of 2nd condition, 1st condition, and 3rd condition. Further, the determination of the leakage diagnosis execution condition may be performed only by the third condition.

1 is a schematic diagram illustrating an overall configuration of an evaporative fuel processing system (Example 1). FIG. 3 is a cross-sectional view showing the overall structure of a leak check module (Example 1). (Example 1) which is the characteristic view which showed the two-dimensional map. 10 is a flowchart illustrating a leak check method (Example 1). It is the flowchart which showed the leak check method (conventional technique).

Explanation of symbols

1 Leak check module 2 Electric air pump (electric pump)
3 Electric Motor 4 Solenoid Valve 5 Solenoid Coil 6 Check Valve 7 Orifice Plate 9 Pressure Sensor 10 ECU (Pump Control Unit, Atmosphere Temperature Estimating Means, Pump Temperature Estimating Means, Engine Control Unit)
11 Fuel tank 12 Canister 14 Engine intake pipe 21 First case (housing)
22 Second case (housing)
23 Third case (housing)
24 4th case (housing)
71 Outside air temperature sensor (atmosphere temperature sensor)
72 Engine intake air temperature sensor (atmosphere temperature sensor)
73 Engine coolant temperature sensor (Temperature sensor other than ambient temperature sensor)

Claims (8)

(A) an electric pump that is incorporated in an engine control system or a vehicle control system and pressurizes and discharges the air sucked inside;
(B) An electric pump control including a pump control unit that controls an operation state of the electric pump so as to start operation of the electric pump when a predetermined pump operation condition is satisfied after the engine is started or stopped. In the device
The pump control unit has atmosphere temperature estimation means for estimating the temperature of the atmosphere around the electric pump, and pump temperature estimation means for estimating the temperature inside the electric pump, and is estimated by the atmosphere temperature estimation means. An electric pump control device that prohibits operation of the electric pump when a temperature difference between the ambient temperature and the pump temperature estimated by the pump temperature estimating means is equal to or greater than a dew condensation determination value. In the electric pump control device according to claim 1,
The electric pump control device, wherein the pump control unit includes a pressure sensor that detects an atmospheric pressure, and corrects the dew condensation determination value based on the atmospheric pressure detected by the pressure sensor. In the electric pump control device according to claim 1 or 2,
The electric pump control apparatus, wherein the electric pump is a vane pump. A leak diagnosis apparatus for an evaporative fuel processing system that introduces evaporative fuel volatilized in a fuel tank into an intake pipe of an engine via a canister,
(A) an electric air pump incorporated in the evaporative fuel processing system and depressurizing or pressurizing the closed space of the evaporative fuel processing system;
(B) When a predetermined pump operation condition is established after the engine is stopped, the operation state of the electric air pump is controlled so as to start the operation of the electric air pump, and leakage diagnosis in the enclosed space of the evaporated fuel processing system is performed. In a leak diagnosis apparatus for a fuel vapor processing system comprising a pump control unit for performing
The pump control unit has atmosphere temperature estimation means for estimating the temperature of the atmosphere around the electric air pump, and pump temperature estimation means for estimating the temperature inside the electric air pump,
Vaporized fuel characterized in that the operation of the electric air pump is prohibited when the temperature difference between the ambient temperature estimated by the ambient temperature estimation means and the pump temperature estimated by the pump temperature estimation means is equal to or greater than a dew condensation determination value. Leak diagnostic device for processing system. A leak diagnosis apparatus for an evaporative fuel processing system that introduces evaporative fuel volatilized in a fuel tank into an intake pipe of an engine via a canister,
(A) a leak check module having an electric air pump incorporated in the evaporative fuel processing system and depressurizing or pressurizing the closed space of the evaporative fuel processing system;
(B) When a predetermined pump operation condition is established after the engine is stopped, the operation state of the electric air pump is controlled so as to start the operation of the electric air pump, and leakage diagnosis in the enclosed space of the evaporated fuel processing system is performed. In a leak diagnosis apparatus for a fuel vapor processing system comprising a pump control unit for performing
The pump control unit has atmosphere temperature estimation means for estimating the temperature of the atmosphere around the electric air pump, and pump temperature estimation means for estimating the temperature inside the electric air pump,
Vaporized fuel characterized in that the operation of the electric air pump is prohibited when the temperature difference between the ambient temperature estimated by the ambient temperature estimation means and the pump temperature estimated by the pump temperature estimation means is equal to or greater than a dew condensation determination value. Leak diagnostic device for processing system. In the leak diagnosis apparatus for an evaporative fuel processing system according to claim 4 or 5,
The electric air pump is covered with a solenoid valve together with a housing and integrated with the solenoid valve. In the leak diagnostic apparatus for an evaporated fuel processing system according to any one of claims 4 to 6,
The pump control unit includes a pressure sensor for detecting atmospheric pressure, and corrects the dew condensation determination value based on the atmospheric pressure detected by the pressure sensor. . In the leak diagnosis apparatus for an evaporative fuel processing system according to any one of claims 4 to 7,
The electric air pump is a vane type pump.

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