JP2017067010A - Diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diagnostic device that can diagnose if there is any anomaly of fuel gas piping.SOLUTION: ECU 10 that is the diagnostic device includes: an intake air temperature acquisition part 14 for acquiring temperature of fluid flowing through an air intake piping 21 and supplied to an engine EG; and a diagnostic part 18 for diagnosing if there is any anomaly of second purge piping 46 that is the fuel gas piping. The diagnostic part 18 performs diagnosis based on the temperature acquired by the intake air temperature acquisition part 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a diagnostic apparatus for diagnosing a fuel gas pipe that supplies fuel gas to a portion upstream of a supercharger in an intake pipe of an engine.

  A technique for improving the fuel efficiency of an engine by supplying unburned fuel gas to an intake pipe of the engine is known. For example, Patent Document 1 described below describes a device that once collects fuel gas generated in a fuel tank by a canister and supplies the fuel gas to an intake pipe. The fuel gas is supplied from the canister to the intake pipe through a fuel gas pipe connected to the canister and the intake pipe. Further, the purge of the fuel gas from the canister is performed using a negative pressure generated when combustion air flows through the intake pipe.

  The device described in Patent Document 1 below diagnoses a fuel gas supply system including a canister. Specifically, the apparatus detects the pressure in the fuel tank and diagnoses whether there is an abnormality in the supply system based on the pressure.

JP-A-4-318268

  By the way, as a measure for improving fuel efficiency in recent years, so-called “downsizing” in which the engine displacement is reduced and the output that decreases with the reduction is supplemented by a supercharger has become widespread. The supercharger drives the turbine using the kinetic energy of the combustion gas discharged from the engine, and pressurizes the combustion air by a compressor that is driven along with the turbine. The combustion air pressurized by the compressor is supplied to the engine via the intake pipe.

  In the case of an engine that receives the assistance of a supercharger, a portion of the intake pipe downstream of the compressor has a positive pressure while the compressor is being driven. Therefore, the fuel gas pipe for supplying the fuel gas described above needs to be connected to a portion of the intake pipe upstream of the compressor in order to apply a negative pressure generated in the intake pipe. In such a configuration, when an abnormality such as a poor connection between the fuel gas pipe and the intake pipe occurs, the fuel gas may be released from the fuel gas pipe to the atmosphere. The above Patent Document 1 does not disclose a specific diagnosis method regarding the presence or absence of such abnormality in the fuel gas piping.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a diagnostic apparatus capable of diagnosing the presence or absence of abnormality in the fuel gas piping.

  In order to solve the above-described problem, a diagnostic device according to the present invention includes a fuel gas pipe that supplies fuel gas to a portion upstream of a supercharger (23) in an intake pipe (21) of an engine (EG). 46, 72) for diagnosing (10, 10A), an intake air temperature acquisition unit (14) for acquiring the temperature of the fluid flowing through the intake pipe and supplied to the engine, and the fuel gas pipe And a diagnosis unit (18) for diagnosing the presence or absence of abnormality. The diagnosis unit performs the diagnosis based on the temperature acquired by the intake air temperature acquisition unit.

  A portion of the intake pipe upstream of the supercharger has a negative pressure both when the supercharger is driven and when it is not driven. Accordingly, when an abnormality such as a poor connection with the intake pipe occurs in the fuel gas pipe, external air flows into the intake pipe from the abnormal portion. As a result, the temperature of the fluid flowing in the intake pipe varies. Since the present invention makes a diagnosis based on the temperature of the fluid having a correlation with the connection of the fuel gas pipe in this way, it is possible to diagnose the presence or absence of an abnormality in the fuel gas pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the diagnostic apparatus which can diagnose the presence or absence of abnormality in fuel gas piping can be provided.

It is a schematic diagram which shows ECU etc. which concern on 1st Embodiment. It is a functional block diagram which shows ECU of FIG. It is a flowchart which shows the process which ECU of FIG. 1 performs. It is a schematic diagram which shows ECU etc. which concern on 2nd Embodiment. It is a flowchart which shows the process which ECU of FIG. 4 performs.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  The ECU 10 that is the diagnostic device according to the first embodiment will be described with reference to FIGS. 1 to 3. First, the vehicle GC equipped with the ECU 10 will be described. As shown in FIG. 1, the vehicle GC includes an engine EG, an intake system 20, a fuel tank 30, and an evaporation gas supply system 40.

  The engine EG is an internal combustion engine that uses gasoline as fuel. The engine EG is disposed in the engine room ER of the vehicle GC. The engine EG has a plurality of cylinders (not shown). Each cylinder generates torque by repeatedly performing each stroke of an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The torque is output via a crankshaft (not shown) included in the engine EG and used for traveling of the vehicle GC.

  The intake system 20 is a part that supplies combustion air to each cylinder of the engine EG. The intake system 20 includes an intake pipe 21, an air element 22, a compressor 23, an intercooler 24, a throttle valve 25, and a surge tank 26.

  The intake pipe 21 is a tubular member having a flow path therein. The intake pipe 21 has an intake manifold 27 branched into a plurality at the downstream end thereof. The intake pipe 21 takes in air from the outside of the vehicle GC and diverts the air to guide it into the cylinders of the engine EG.

  The air element 22 is a filter-like member that removes foreign matters from the fluid passing therethrough. The air element 22 is provided in the intake pipe 21. Thereby, the air element 22 removes foreign matter in the air that is taken in from the outside of the vehicle GC and supplied to the engine EG.

  The compressor 23 forms a part of the supercharger and is a fluid machine that compresses fluid by rotating. The compressor 23 is provided in a portion of the intake pipe 21 on the downstream side of the air element 22. The compressor 23 is connected to a turbine (not shown) that constitutes a part of the supercharger. The turbine is a prime mover that converts energy of fluid into mechanical power, and is provided in an exhaust gas passage (not shown). When the combustion gas generated in the combustion stroke of the engine EG flows through the exhaust gas flow path, the turbine rotates using the energy of the combustion gas. The rotational torque of the turbine is transmitted to the compressor 23 by a shaft (not shown). As a result, the compressor 23 rotates and sucks and compresses the air on the upstream side of the intake pipe 21 and supplies it to the downstream side.

  The intercooler 24 is a heat exchanger provided in a portion of the intake pipe 21 on the downstream side of the compressor 23. The intercooler 24 is formed with a flow path (not shown) through which air flows. The air heated to a high temperature by being compressed by the compressor 23 is supplied to the flow path in the intercooler 24. The air flowing through the flow path dissipates heat by exchanging heat with the air flowing outside the intercooler 24, and the temperature decreases.

  The throttle valve 25 is an open / close valve provided in a portion of the intake pipe 21 downstream of the intercooler 24. The throttle valve 25 has an electric motor and a valve body (not shown). The electric motor is driven based on a control signal received from the ECU 10 described later, and moves the valve body. When the valve body moves, the opening degree of the internal flow path of the throttle valve 25 is adjusted.

  The surge tank 26 is a container-like device provided in a portion of the intake pipe 21 downstream of the surge tank 26. The cross-sectional area in the surge tank 26 is larger than the cross-sectional area of other parts of the intake pipe 21. As a result, even when an unintended pressure fluctuation occurs in one cylinder of the engine EG, it is possible to mitigate adverse effects on other cylinders.

  The fuel tank 30 is a tank that stores gasoline that is the fuel of the engine EG. Usually, the fuel is stored in the fuel tank 30 in a liquid state. The fuel tank 30 has a fuel pump (not shown) therein. The fuel pump is driven based on a control signal received from the ECU 10 and pumps fuel to a fuel supply pipe (not shown) connected to the fuel tank 30. The fuel is guided to the engine EG through a fuel supply pipe or the like, and is injected from an injector (not shown) to be atomized and supplied into each cylinder.

  The evaporation gas supply system 40 is a portion that supplies fuel gas, which is gaseous gasoline generated in the fuel tank 30 (hereinafter, this fuel gas is also referred to as “evaporation gas”) to the intake pipe 21. The evaporation gas supply system 40 includes a communication pipe 41, a canister 42, and a purge pipe 43.

  The communication pipe 41 is a tubular member that is disposed between the fuel tank 30 and the canister 42 and that has an end portion connected thereto. The fuel tank 30 and the canister 42 communicate with each other through the communication pipe 41.

  An adsorbent (not shown) is disposed in the internal space of the canister 42. As this adsorbent, a porous member having a large number of pores on the surface, such as activated carbon, can be used. The canister 42 has an open port (not shown) and is open to the atmosphere at the open port.

  The purge pipe 43 is a tubular member having one end connected to the canister 42. The purge pipe 43 is formed to extend from the canister 42 and branch in the middle thereof, and includes a first purge pipe 44 and a second purge pipe 46. The end of the first purge pipe 44 is connected to the intake manifold 27. A first purge valve 45 that is an on-off valve is provided in the middle of the first purge pipe 44. The end of the second purge pipe 46 is connected to the intake pipe 21. Specifically, the end of the second purge pipe 46 is connected to a portion of the intake pipe 21 upstream of the compressor 23 and downstream of the air element 22. A second purge valve 47 that is an on-off valve is provided in the middle of the second purge pipe 46.

  Next, the function of the evaporation gas supply system 40 configured as described above will be described. When the fuel is volatilized in the fuel tank 30 and evaporated gas is generated, the evaporated gas is guided to the canister 42 through the communication pipe 41.

  The evaporative gas guided to the canister 42 is adsorbed by an adsorbent disposed in the internal space. The evaporative gas adsorbed by the adsorbent is released by its action when the pressure in the purge pipe 43 becomes negative.

  For example, when the engine EG is operating without the compressor 23 being driven, both the first purge valve 45 and the second purge valve 47 are opened. As a result, the negative pressure generated by the air flowing in the intake pipe 21 and the intake manifold 27 on the downstream side thereof is removed from the purge pipe 43 and the canister via the first purge pipe 44 and the second purge pipe 46. Acts on 42. When the inside of the canister 42 becomes negative pressure, air is taken in from the above-described opening and passes through the adsorbent. As a result, the evaporation gas is released from the adsorbent into the air.

  On the other hand, when the engine EG is operating with the compressor 23 being driven, only the second purge valve 47 is opened. As described above, the second purge pipe 46 provided with the second purge valve 47 is connected to the intake pipe 21 on the upstream side of the compressor 23. Therefore, when the compressor 23 is driven, a negative pressure generated in association with the compressor 23 acts on the purge pipe 43 and the canister 42 via the second purge pipe 46. When the inside of the canister 42 becomes negative pressure, air is taken in from the above-described opening and passes through the adsorbent. As a result, the evaporation gas is released from the adsorbent into the air.

  Note that, when the compressor 23 is driven, the intake manifold 27 on the downstream side of the compressor 23 has a positive pressure. Accordingly, the first purge valve 45 is closed in order to prevent the inflow of air from the intake manifold 27 to the first purge pipe 44.

  The evaporative gas released from the adsorbent in the canister 42 in this way flows into the intake pipe 21 and merges with the air flowing through it. The mixed fluid of the evaporation gas and air flows through the intake pipe 21 as it is and is guided into each cylinder of the engine EG. As a result, it is possible to improve the fuel efficiency of the engine EG by using the engine EG without releasing the evaporation gas to the atmosphere.

  In addition, by providing two pipes, the first purge pipe 44 and the second purge pipe 46, it is possible to secure an opportunity to make the inside of the canister 42 have a negative pressure even in the configuration in which the compressor 23 is arranged in the intake pipe 21. It becomes. As a result, it is possible to reliably release the evaporation gas from the adsorbent.

  Next, an ECU (Electronic Control Unit) 10 will be described with reference to FIG. The ECU 10 is partially or entirely configured by an analog circuit or a digital processor. In any case, in order to fulfill the function of outputting a control signal based on the received signal, the ECU 10 includes a functional control block.

  FIG. 2 shows the ECU 10 as a functional control block diagram. The software module incorporated in the analog circuit or digital processor that constitutes the ECU 10 does not necessarily have to be divided like the control block shown in FIG. That is, an actual analog circuit or module may be configured to function as a plurality of control blocks shown in FIG. 2, or may be further subdivided. A person skilled in the art can appropriately change the actual configuration inside the ECU 10 as long as the processing described later can be executed.

  The ECU 10 is electrically connected to various sensors such as a water temperature sensor 51, an outside air temperature sensor 52, an intake air temperature sensor 53, a vehicle speed sensor 54, and a valve opening sensor 55. The water temperature sensor 51 is a sensor that is provided in a cooling circuit (not shown) that circulates cooling water through the engine EG, and generates and transmits a signal corresponding to the temperature of the cooling water. The outside air temperature sensor 52 is a sensor that is disposed in a part of the vehicle GC that is in contact with outside air, and generates and transmits a signal corresponding to the outside air temperature. The intake air temperature sensor 53 is a sensor that is provided in the intake manifold 27 shown in FIG. 1 and generates and transmits a signal corresponding to the temperature of the fluid flowing through the intake manifold 27. The vehicle speed sensor 54 is a sensor that is attached to an axle (not shown) of the vehicle GC and generates and transmits a signal corresponding to the rotation speed of the axle. The valve opening sensor 55 is a sensor that is provided in the second purge valve 47 shown in FIG. 1 and generates and transmits a signal corresponding to the opening of the second purge valve 47.

  The ECU 10 is also electrically connected to in-vehicle devices such as the engine EG, the throttle valve 25, and the notification device 60. ECU10 adjusts the applied voltage etc. to the injector provided in engine EG, and an ignition plug by transmitting a control signal to engine EG. The notification device 60 is a device for performing various notifications to passengers of the vehicle GC. The notification device 60 is configured by a known device such as a display panel or a buzzer. The ECU 10 controls the operation of the notification device 60 by transmitting a control signal.

  In the present application, “electrically connected” is not limited to a form in which signals are connected to each other via a signal line, but may include a form in which wireless communication is possible.

  The ECU 10 includes a storage unit 11, a cooling water temperature acquisition unit 12, an outside air temperature acquisition unit 13, an intake air temperature acquisition unit 14, a vehicle speed acquisition unit 15, a valve opening acquisition unit 16, an engine room temperature acquisition unit 17, and a diagnosis unit 18. Have.

  The storage unit 11 is a part that stores various information. The storage unit 11 is configured by, for example, a nonvolatile memory. Information such as a map is stored in the storage unit 11 in advance. The information is read by the cooling water temperature acquisition unit 12 and used for a predetermined calculation. Moreover, the memory | storage part 11 can memorize | store the calculation result of the cooling water temperature acquisition part 12, etc. FIG.

  The cooling water temperature acquisition unit 12 is a part that performs a predetermined calculation based on a signal received from the water temperature sensor 51 and acquires the temperature of the cooling water. The outside air temperature acquisition unit 13 is a part that performs a predetermined calculation based on a signal received from the outside air temperature sensor 52 and acquires the outside air temperature. The intake air temperature acquisition unit 14 is a part that performs a predetermined calculation based on a signal received from the intake air temperature sensor 53 and acquires the temperature of the fluid flowing in the intake manifold 27. The vehicle speed acquisition unit 15 is a part that performs a predetermined calculation based on a signal received from the vehicle speed sensor 54 and acquires a moving speed of the vehicle GC with respect to the road surface (hereinafter also referred to as “vehicle speed”). The valve opening degree obtaining unit 16 is a part that performs a predetermined calculation based on a signal received from the valve opening degree sensor 55 and obtains the opening degree of the second purge valve 47.

  The engine room temperature acquisition unit 17 is a part that acquires the temperature Te (specifically, the temperature of air present in the engine room ER) Te of the engine room ER. In the first embodiment, the temperature Te is estimated based on parameters such as the temperature of the cooling water acquired by the cooling water temperature acquisition unit 12 and the like, the outside air temperature, the vehicle speed, and the elapsed time after the engine EG is started. Is the value to be Specifically, the engine room temperature acquisition unit 17 compares these parameters correlated with the temperature Te of the engine room ER with the map stored in the storage unit 11, and based on this comparison, the temperature of the engine room ER Get an estimate of Te.

  By the way, in the vehicle GC configured as described above, an abnormality may occur in the second purge pipe 46, which may cause a problem related to the processing of the evaporation gas. That is, when the normal state is reached, the end of the second purge pipe 46 connected to the intake pipe 21 is disconnected, so that the evaporated gas flowing through the second purge pipe 46 may be released to the atmosphere.

  Therefore, the ECU 10 executes a process for diagnosing whether or not the second purge pipe 46 is abnormal. The diagnosis process executed by the ECU 10 will be described with reference to FIG. The diagnostic process shown in FIG. 3 is executed by the ECU 10 in a predetermined cycle.

  The ECU 10 performs the diagnosis based on the fact that the hot air in the engine room ER flows into the intake pipe 21 when the end of the second purge pipe 46 is detached from the intake pipe 21. For convenience, the processing executed in each functional block such as the valve opening degree acquisition unit 16 of the ECU 10 may be described as being executed by the ECU 10 as a whole.

  First, the ECU 10 determines whether or not the second purge valve 47 is closed in step S100 shown in FIG. That is, the ECU 10 determines whether or not the evaporative gas released from the canister 42 does not flow into the intake pipe 21 through the second purge pipe 46. When it is determined that the second purge valve 47 is not closed, the ECU 10 ends the diagnostic process without executing the processes after step S101. On the other hand, when it is determined that the second purge valve 47 is closed, the ECU 10 proceeds to the process of step S101.

  Next, in step S101, the ECU 10 determines whether or not the temperature Te of the engine room ER acquired by the engine room temperature acquisition unit 17 is equal to or higher than the temperature threshold KT1. This temperature threshold value KT1 is a value corresponding to the temperature of the engine room ER when the warm-up of the engine EG is completed. Temperature threshold value KT1 is predetermined based on a test using engine EG or the like. When it is determined that the temperature Te of the engine room ER is equal to or higher than the temperature threshold KT1, the ECU 10 proceeds to the process of step S102 and sets 1 to the flag xflag. On the other hand, if it is determined that the temperature Te of the engine room ER is not equal to or higher than the temperature threshold KT1, the ECU 10 proceeds to the process of step S103 and sets 0 to the flag xflag. When the ECU 10 ends the process of step S102 or step S103, the ECU 10 proceeds to the process of step S104.

  Next, in step S104, the ECU 10 determines whether or not the value set in the flag xflag has been changed from 0 to 1 in the current cycle. That is, the ECU 10 determines whether or not the temperature Te of the engine room ER has changed from a state below the temperature threshold value KT1 to a state above the temperature threshold value KT1 in the current cycle. If it is determined that the value set in the flag xflag has been changed from 0 to 1 in the current cycle, the ECU 10 proceeds to the process of step S106. On the other hand, if it is determined that the value set in the flag xflag has not been changed from 0 to 1 in the current cycle, the ECU 10 proceeds to the process of step S105.

  Next, in step S105, the ECU 10 determines whether 0 is set in the flag xflag. That is, the ECU 10 determines whether or not the temperature Te of the engine room ER is less than the temperature threshold value KT1. If it is determined that the temperature Te of the engine room ER is not less than the temperature threshold value KT1, the ECU 10 proceeds to the process of step S107 without executing the process of step S106. On the other hand, when it is determined that the temperature Te of the engine room ER is lower than the temperature threshold value KT1, the ECU 10 proceeds to the process of step S106.

  Next, in Step S106, the ECU 10 sets the temperature Tin of the fluid in the intake manifold 27 at that time as the reference temperature Temp. That is, the reference temperature Temp is based on the signal output from the intake air temperature sensor 53 when the temperature Te of the engine room ER changes from a state below the temperature threshold KT1 to a state above the temperature threshold KT1. Is the temperature to get. When the ECU 10 finishes the process of step S106, the ECU 10 proceeds to the process of step S107.

  Next, in step S107, the ECU 10 determines whether or not the change amount (Tin-Temp) of the temperature Tin of the fluid flowing in the intake manifold 27 from the reference temperature Temp is equal to or greater than the change amount threshold value KT2. The change amount threshold value KT2 is a value determined based on a temperature that can be reached by the temperature Tin when hot air in the engine room ER flows into the intake pipe 21 after the warm-up of the engine EG is completed. The change amount threshold value KT2 is determined in advance based on a test using the engine EG or the like. When the change amount (Tin-Temp) is equal to or greater than the change amount threshold value KT2, that is, when it is estimated that the air in the engine room ER has flowed into the intake pipe 21 and the temperature Tin has increased, the ECU 10 performs the process of step S108. Proceed to

  Next, the ECU 10 increments the counter cfail by 1 in step S108. That is, the counter cfail corresponds to the number of times that the air in the engine room ER has been continuously estimated to have flowed into the intake pipe 21 in step S107 described above. When the ECU 10 ends the process of step S108, the ECU 10 proceeds to the process of step S110.

  On the other hand, when it is determined in step S107 that the change amount (Tin-Temp) is not equal to or greater than the change amount threshold value KT2, that is, when it is estimated that the air in the engine room ER does not flow into the intake pipe 21. The ECU 10 proceeds to the process of step S109. In step S109, the ECU 10 sets 0 to the counter cfail. When the ECU 10 finishes the process of step S109, the ECU 10 proceeds to the process of step S110.

  Next, in step S110, the ECU 10 determines whether or not the counter cfail is greater than or equal to the counter threshold value KC. When the counter cfail is equal to or greater than the counter threshold value KC, it can be estimated that there is a high possibility that the air in the engine room ER has flowed into the intake pipe 21. Therefore, in this case, the ECU 10 proceeds to the process of step S111 and diagnoses that the end portion of the second purge pipe 46 is detached from the intake pipe 21. Further, the ECU 10 proceeds to the process of step S113 and operates the notification device 60.

  On the other hand, if it is determined in step S110 that the counter cfail is not greater than or equal to the counter threshold value KC, the ECU 10 proceeds to the process of step S112 and diagnoses that the end of the second purge pipe 46 is not detached from the intake pipe 21.

  As described above, a portion of the intake pipe 21 upstream of the compressor 23 that is a supercharger has a negative pressure both when the compressor 23 is driven and when it is not driven. Therefore, when an abnormality such as a poor connection with the intake pipe 21 occurs in the second purge pipe 46 that is a fuel gas pipe, the air in the engine room ER flows into the intake pipe 21 from the abnormal location. As a result, the temperature Tin of the fluid flowing in the intake pipe 21 including the intake manifold 27 varies. Since the ECU 10 makes a diagnosis based on the fluid temperature Tin having a correlation with the connection of the second purge pipe 46 as described above, it is possible to diagnose whether or not the second purge pipe 46 is abnormal.

  Moreover, ECU10 is provided with the engine room temperature acquisition part 17 which acquires the temperature Te of the engine room ER in which the engine EG is arrange | positioned. The diagnosis unit 18 of the ECU 10 performs diagnosis when the temperature Te acquired by the engine room temperature acquisition unit 17 is equal to or higher than a predetermined temperature threshold value KT1. Accordingly, in the state where the temperature Te of the engine room ER is sufficiently high and the temperature of the fluid flowing in the intake manifold 27 clearly changes when the air in the engine room ER flows into the intake pipe 21, the diagnosis unit 18 Diagnosis can be performed. As a result, the accuracy of diagnosis by the diagnosis unit 18 can be increased.

  Further, the diagnosis unit 18 of the ECU 10 uses a fuel gas pipe based on the fact that the change amount (Tin-Temp) of the temperature Tin acquired by the intake air temperature acquisition unit 14 is equal to or greater than a predetermined change threshold value KT2. It is diagnosed that there is an abnormality in a certain second purge pipe 46. Thereby, based on the fact that the temperature of the fluid flowing in the intake pipe 21 has changed significantly, it can be diagnosed that an abnormality such as a poor connection with the intake pipe 21 has occurred in the second purge pipe 46. As a result, the accuracy of diagnosis by the diagnosis unit 18 can be increased.

  Further, the diagnosis unit 18 of the ECU 10 sets the temperature Tin acquired by the intake air temperature acquisition unit 14 when the temperature Te acquired by the engine room temperature acquisition unit 17 is equal to or higher than the temperature threshold value KT1 as the reference temperature Temp. Furthermore, the diagnosis unit 18 is a fuel gas pipe based on the change amount (Tin-Temp) of the temperature Tin acquired by the intake air temperature acquisition unit 14 from the reference temperature Temp being equal to or greater than the change amount threshold value KT2. The second purge pipe 46 is diagnosed as having an abnormality. As a result, the temperature Tin of the fluid flowing in the intake manifold 27 when the engine EG has been warmed up is set as the reference temperature Temp, and then the temperature Tin shows an increase that cannot be shown in the normal state. It can be diagnosed that the 2-purge pipe 46 is abnormal.

  The diagnosis unit 18 of the ECU 10 diagnoses whether there is an abnormality in the second purge pipe 46 that supplies the evaporation gas that is the fuel gas generated in the fuel tank 30 that stores the liquid fuel. Accordingly, it is possible to diagnose the presence or absence of an abnormality in which the evaporation gas is released into the atmosphere due to poor connection of the second purge pipe 46 or the like.

  Further, the diagnosis unit 18 of the ECU 10 performs diagnosis when the second purge pipe 46 is closed. In the state where the second purge pipe 46 is opened, the evaporated gas generated in the fuel tank 30 flows into the intake pipe 21. If the diagnosis of the second purge pipe 46 is performed in this state, the cause of the variation in the temperature Tin acquired by the intake air temperature acquisition unit 14 is either the inflow of air from the engine room ER or the inflow of evaporation gas. It is difficult to determine whether there is any.

  On the other hand, the diagnosis unit 18 of the ECU 10 performs the diagnosis in a state where the second purge pipe 46 is closed and the evaporation gas does not flow into the intake pipe 21. As a result, the diagnosis of the second purge pipe 46 can be performed based only on the influence of the inflow of air from the engine room ER, and the accuracy of the diagnosis can be increased.

  An ECU 10A that is a diagnostic device according to the second embodiment will be described with reference to FIGS. The ECU 10A is a control device mounted on the vehicle GCA. The ECU 10A differs from the ECU 10 according to the first embodiment described above mainly in diagnosing whether or not the second PCV pipe 72 is abnormal. Of the ECU 10A and the vehicle GCA, the same components as those of the ECU 10 and the vehicle GC described above are appropriately denoted by the same reference numerals and description thereof is omitted.

  First, the vehicle GCA will be described. As shown in FIG. 4, the vehicle GCA includes a PCV system 70 in addition to the engine EG, the intake system 20, and the fuel tank 30. The PCV system 70 includes a first PCV pipe 71 and a second PCV pipe 72.

  The first PCV pipe 71 is a tubular member having a flow path therein. One end of the first PCV pipe 71 is connected to a crankcase (not shown) of the engine EG, and the other end is connected to the surge tank 26. Thereby, the crankcase of the engine EG and the surge tank 26 are communicated with each other via the first PCV pipe 72. A PCV valve 73 is provided in the middle of the first PCV pipe 71. The PCV valve 73 is a backflow prevention valve that opens or closes based on the pressure difference between the upstream side and the downstream side.

  The second PCV pipe 72 is a tubular member having a flow path therein. One end of the second PCV pipe 72 is connected to a crankcase (not shown) of the engine EG, and the other end is connected to the intake pipe 21. Specifically, the other end of the second PCV pipe 72 is connected to a portion of the intake pipe 21 upstream of the compressor 23 and downstream of the air element 22.

  Subsequently, functions of the PCV system 70 configured as described above will be described. In the engine EG, fuel gas (hereinafter, this fuel gas is also referred to as “blow-by gas”) may leak from a gap between a piston (not shown) of each cylinder and the cylinder. The blow-by gas that stays in the crankcase may cause engine oil deterioration, metal corrosion, and the like. In order to suppress such problems, the PCV system 70 functions to discharge blow-by gas from the crankcase and return it to each cylinder. The PCV system 70 includes a first PCV pipe 71 and a second PCV pipe 72 that are reflux pipes.

  When the engine EG is operating without the compressor 23 being driven, the negative pressure generated when air flows through the intake pipe 21 acts on the crankcase via the first PCV pipe 71 and the second PCV pipe 72. To do. Thereby, blow-by gas is discharged from the crankcase.

  On the other hand, when the engine EG is operating with the compressor 23 being driven, blow-by gas is discharged through the second PCV pipe 72. As described above, the second PCV pipe 72 is connected to the intake pipe 21 on the upstream side of the compressor 23. Therefore, when the compressor 23 is driven, a negative pressure generated along with the compressor 23 acts on the crankcase via the second PCV pipe 72. Thereby, blow-by gas is discharged from the crankcase.

  In the state where the compressor 23 is driven, the pressure in the surge tank 26 on the downstream side of the compressor 23 is positive. In the first PCV pipe 71, the PCV valve 73 is closed based on the fact that the pressure on the downstream side is higher than the pressure on the upstream side of the PCV valve 73. Thereby, the inflow of air from the surge tank 26 to the first PCV pipe 71 is prevented.

  The blow-by gas discharged from the crankcase of the engine EG in this way flows into the intake pipe 21 and merges with the air flowing through it. The mixed fluid of blow-by gas and air flows through the intake pipe 21 as it is and is supplied to each cylinder of the engine EG. As a result, it is possible to improve the fuel efficiency of the engine EG by using the engine EG without releasing the blowby gas to the atmosphere.

  By the way, in vehicle GCA comprised as mentioned above, when abnormality arises in the 2nd PCV piping 72, there exists a possibility that the malfunction concerning the processing of blow-by gas may arise. That is, when the end portion of the second PCV pipe 72 connected to the intake pipe 21 is disconnected at the normal time, the blow-by gas flowing through the second PCV pipe 72 may be released to the atmosphere.

  Therefore, the ECU 10A executes a process for diagnosing whether or not the second PCV pipe 72 is abnormal. A diagnosis process executed by the ECU 10A will be described with reference to FIG. The diagnostic process shown in FIG. 5 is executed by the ECU 10A in a predetermined cycle.

  As shown in FIG. 5, the diagnostic process executed by the ECU 10A is similar to the diagnostic process executed by the ECU 10 according to the first embodiment described above. Specifically, first, the vehicle GCA according to the second embodiment does not include the second purge valve 47 unlike the vehicle GC according to the first embodiment, and thus the ECU 10A corresponds to step S100 shown in FIG. Processing is not executed. However, the processing from step S201 to step S213 executed by the ECU 10A shown in FIG. 5 corresponds to the processing from step S101 to step S113 executed by the ECU 10 shown in FIG. That is, the ECU 10A diagnoses whether there is an abnormality in the second PCV pipe 72 based on the fact that the hot air in the engine room ER flows into the intake pipe 21 when the end of the second PCV pipe 72 is removed from the intake pipe 21. I do.

  As described above, the ECU 10A according to the second embodiment diagnoses whether there is an abnormality in the second PCV pipe 72 that supplies blow-by gas that is unburned fuel gas generated in the engine EG. Thereby, it can be diagnosed whether there is an abnormality in which blow-by gas is released into the atmosphere due to poor connection of the second PCV pipe 72 or the like.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. Each element included in each of the specific examples described above and their arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be appropriately changed.

  For example, in the first embodiment described above, the ECU 10 acquires the temperature of the engine room ER by estimation based on the temperature of the cooling water or the like, but the present invention is not limited to this. That is, a sensor that directly detects the temperature of the engine room ER may be arranged in the engine room ER, and the temperature of the engine room ER may be acquired based on the detection of the sensor.

ER: Engine room EG: Engine 10, 10A: ECU (diagnostic device)
14: intake air temperature acquisition unit 18: diagnosis unit 21: intake pipe 23: compressor (supercharger)
30: Fuel tank 46: Second purge pipe (purge pipe)
72: Second PCV pipe (reflux pipe)

Claims (6)

A diagnostic device (10, 10A) for diagnosing a fuel gas pipe (46, 72) for supplying fuel gas to a portion upstream of a supercharger (23) in an intake pipe (21) of an engine (EG). And
An intake air temperature acquisition unit (14) for acquiring a temperature of a fluid flowing through the intake pipe and supplied to the engine;
A diagnosis unit (18) for diagnosing the presence or absence of abnormality of the fuel gas pipe,
The diagnostic unit is a diagnostic device that performs the diagnosis based on the temperature acquired by the intake air temperature acquisition unit. An engine room temperature acquisition unit (17) for acquiring the temperature of an engine room (ER) in which the engine is disposed;
The diagnostic device according to claim 1, wherein the diagnosis unit performs the diagnosis when the temperature acquired by the engine room temperature acquisition unit is equal to or higher than a predetermined temperature threshold.   The diagnosis unit diagnoses that there is an abnormality in the fuel gas pipe based on a change amount of the temperature acquired by the intake air temperature acquisition unit being equal to or greater than a predetermined change amount threshold value. The diagnostic device described.   The diagnosis unit uses the temperature acquired by the intake air temperature acquisition unit when the temperature acquired by the engine room temperature acquisition unit is equal to or higher than the temperature threshold, and the temperature acquired by the intake air temperature acquisition unit. The diagnosis apparatus according to claim 3, wherein the fuel gas piping is diagnosed as having an abnormality based on a change amount from the reference being equal to or greater than the change amount threshold value.   The diagnosis unit includes at least a purge pipe (46) for supplying fuel gas generated in a fuel tank (30) for storing liquid fuel, and a recirculation pipe (72) for supplying unburned fuel gas generated in the engine. The diagnostic apparatus according to any one of claims 1 to 4, which diagnoses the presence or absence of one abnormality.   The diagnostic apparatus according to claim 5, wherein the diagnosis unit performs the diagnosis when the purge pipe is blocked.

Images