JP2016118101A - Failure determination device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a misfire during failure determination of an exhaust recirculating device.SOLUTION: A failure determination device which is mounted on a vehicle equipped with an engine 2 having an EGR passage 42 and an EGR valve 43 includes failure determination means for determining failure of the EGR valve 43 based on variation of a detection value of an intake pressure sensor 44 when opening and closing control of the EGR valve 43 is executed during a series mode, and second prescribed time Ta for regulating second failure determination from completion of first failure determination is set longer than first prescribed time T8 for regulating the first failure determination from starting of the engine 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a failure determination technique for an internal combustion engine mounted on a vehicle.

In hybrid vehicles that have been developed in recent years, vehicles capable of traveling mode (series mode) in which a motor generator is driven by an internal combustion engine to generate electric power and driving wheels for traveling are driven only by an electric motor have been developed.
Further, in the hybrid vehicle capable of the above-described travel mode, a technology has been developed for determining a failure of the exhaust system detection means (air-fuel ratio sensor, oxygen concentration sensor, catalyst monitor, etc.) of the internal combustion engine in the travel mode. .

For example, in Patent Document 1, so-called motoring in which fuel supply to an internal combustion engine is stopped and the internal combustion engine is forcibly driven by a motor generator is performed, and a change in the detection value of the intake / exhaust system detection means accompanying the stop of fuel supply A technique for determining a failure of the detection means based on the above is disclosed.
Further, in the hybrid vehicle capable of the above-described travel mode, a technology has been developed that includes an exhaust gas recirculation device (EGR device) that recirculates the exhaust gas of the internal combustion engine to the intake system, and determines a failure of the exhaust gas recirculation device.

  For example, in Patent Document 2, an exhaust gas recirculation device includes an exhaust gas recirculation passage that communicates an exhaust passage and an intake passage of an internal combustion engine, and an exhaust gas recirculation valve that opens and closes the exhaust gas recirculation passage. The exhaust gas recirculation valve is opened and closed, and a failure determination of the exhaust gas recirculation device such as the exhaust gas recirculation valve is performed based on a change in pressure in the intake passage.

Japanese Patent No. 4067001 Japanese Patent No. 4274266

The failure determination means of Patent Document 1 and Patent Document 2 have a problem that power is consumed because motoring is performed. Further, even in a vehicle incapable of motoring, failure determination of the detection means or the like is required.
Thus, for example, it is conceivable to perform a failure determination by forcibly performing a low-load operation when starting the internal combustion engine. However, when performing a failure determination of the exhaust gas recirculation device as in Patent Document 2, the combustion stability of the internal combustion engine may be reduced due to the exhaust gas recirculation.

Furthermore, when performing a failure determination of the exhaust gas recirculation device as in Patent Document 2, it is common to perform exhaust gas recirculation and detection a plurality of times in order to increase the determination accuracy.
However, if the failure determination of the exhaust gas recirculation device is continuously performed a plurality of times during low load operation with a small intake amount in this way, the exhaust gas recirculated to the intake passage at the time of failure determination remains in the intake passage, and the subsequent failure At the time of determination, the concentration of the exhaust gas in the intake air further increases, and the combustion stability of the internal combustion engine may become more unstable and misfire may occur.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and the object of the present invention is to prevent a vehicle failure that prevents misfire when performing a failure determination of the exhaust gas recirculation device during low load operation with a small amount of intake air. It is to provide a determination device.

  In order to achieve the above object, a vehicle failure determination device according to the present invention includes an internal combustion engine that is mounted on a vehicle and includes an exhaust gas recirculation passage that recirculates exhaust gas to an intake passage, and an exhaust gas recirculation valve that opens and closes the exhaust gas recirculation passage. And a detection means for detecting an intake pressure of the internal combustion engine, and a change in a detection value of the detection means when the exhaust gas recirculation valve is controlled to open and close during operation of the internal combustion engine. A failure determining means for determining a failure of the exhaust gas recirculation valve, and a first determination for restricting the failure determination by the failure determining means for the first time from the start of the internal combustion engine until a first predetermined time has elapsed since the start. A second determination time from the start of the internal combustion engine until a second predetermined time has elapsed from the end of the first failure determination by the failure determination means during operation of the internal combustion engine; Disabled with a second failure determination regulating means for regulating the failure determination by the determining means, wherein the second predetermined time, characterized in that it is set the first longer than the predetermined time.

Preferably, the intake air amount detection means for detecting the intake air amount of the internal combustion engine is provided, and the second predetermined time is detected by the intake air amount detection means in the first failure determination. It may be set based on the integrated value of the air amount.
Preferably, the second predetermined time is set shorter as the integrated value of the intake air amount becomes larger.

Preferably, the second failure determination restricting means further determines the failure determination by the failure determination means during the operation of the internal combustion engine from the end of the failure determination one time before the failure determination. It is good to regulate until time passes.
Preferably, the vehicle is driven by the internal combustion engine and can generate power, while being supplied from the drive battery and a motor generator capable of driving the internal combustion engine with electric power supplied from the drive battery. A driving motor for driving the driving wheels with electric power, and driving the motor generator with the driving motor to drive the motor generator and generating electric power while driving the motor generator. The failure determination means may perform the failure determination during the first travel mode.

According to the vehicle failure determination device of the present invention, when determining the failure of the exhaust gas recirculation valve, the first failure determination ends after the first predetermined time during which the first failure determination is restricted from the start of the internal combustion engine. Since the second predetermined time for which the second failure determination is restricted is set longer, the second failure determination is restricted to be performed immediately after the first failure determination is completed.
Therefore, even if the exhaust gas recirculated when the first failure determination is completed remains in the intake passage, the start of the second failure determination after the second predetermined time elapses. Exhaust concentration decreases. As a result, it is possible to suppress a decrease in combustion stability during the second failure determination and to prevent misfire of the internal combustion engine.

1 is a schematic configuration diagram of a plug-in hybrid vehicle according to an embodiment of the present invention. It is a schematic block diagram of the intake / exhaust system of the engine of this embodiment. 7 is a part of a timing chart showing an example of control timing of various control signals in a failure determination method in series mode. It is the remainder of the timing chart which shows one Example of the control timing of the various control signals in the failure determination method in series mode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a plug-in hybrid vehicle (hereinafter referred to as a vehicle 1) according to an embodiment of the present invention.
The vehicle 1 of the present embodiment can travel by driving the front wheels 3 by the output of the engine 2 (internal combustion engine), and also has an electric front motor 4 (drive motor) that drives the front wheels 3 (drive wheels) and a rear wheel. This is a four-wheel drive vehicle including an electric rear motor 6 (drive motor) that drives the wheels 5 (drive wheels).

The engine 2 can drive the drive shaft 8 of the front wheels 3 via the speed reducer 7 and can drive the motor generator 9 via the speed reducer 7 to generate electric power.
The front motor 4 is driven by being supplied with high-voltage power from the drive battery 11 and the motor generator 9 mounted on the vehicle 1 via the front inverter 10, and the drive shaft 8 of the front wheel 3 via the speed reducer 7. Drive. The speed reducer 7 incorporates a clutch 7 a capable of switching connection / disconnection of power between the output shaft of the engine 2 and the drive shaft 8 of the front wheel 3.

The rear motor 6 is driven by being supplied with high voltage power from the drive battery 11 and the motor generator 9 via the rear inverter 12, and drives the drive shaft 14 of the rear wheel 5 via the speed reducer 13.
The electric power generated by the motor generator 9 can charge the driving battery 11 via the front inverter 10 and can supply electric power to the front motor 4 and the rear motor 6.

The drive battery 11 is composed of a secondary battery such as a lithium ion battery, and has a battery module (not shown) configured by collecting a plurality of battery cells. Further, the battery module charge rate (State Of Charge, Hereinafter, a battery monitoring unit 11a for monitoring SOC) and the like is provided.
The front inverter 10 includes a front motor control unit 10a and a generator control unit 10b. The front motor control unit 10 a controls the output of the front motor 4 based on a control signal from the hybrid control unit 20. The generator control unit 10 b has a function of controlling the power generation amount of the motor generator 9 based on a control signal from the hybrid control unit 20.

The rear inverter 12 has a rear motor control unit 12a. The rear motor control unit 12 a has a function of controlling the output of the rear motor 6 based on a control signal from the hybrid control unit 20.
Further, the motor generator 9 is supplied with electric power from the driving battery 11 based on a control signal from the hybrid control unit 20 and can drive the engine 2, and functions as a starter motor of the engine 2. Have

The vehicle 1 is also provided with a charger 21 that charges the drive battery 11 with an external power source.
The hybrid control unit 20 is a control device for performing comprehensive control of the vehicle 1 and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), and the like. Composed.

  On the input side of the hybrid control unit 20, a battery monitoring unit 11a of the driving battery 11, a front motor control unit 10a and a generator control unit 10b of the front inverter 10, a rear motor control unit 12a of the rear inverter 12, an engine control unit 22 ( A failure determination unit, a first failure determination regulation unit, a second failure determination regulation unit), and an accelerator opening sensor 40 for detecting an accelerator operation amount are connected, and detection and operation information from these devices is input. Is done.

On the other hand, on the output side of the hybrid control unit 20, a front motor control unit 10a and a generator control unit 10b of the front inverter 10, a rear motor control unit 12a of the rear inverter 12, a speed reducer 7 (clutch 7a), and an engine control unit 22 are provided. It is connected.
The hybrid control unit 20 calculates a vehicle request output required for driving the vehicle 1 based on the various detection amounts and various operation information of the accelerator opening sensor 40 and the like, and the engine control unit 22, front motor Control signals are sent to the control unit 10a, the generator control unit 10b, the rear motor control unit 12a, and the speed reducer 7 to switch the running mode ((EV mode: electric vehicle mode), series mode, parallel mode), engine 2 and The outputs of the front motor 4 and the rear motor 6 and the output (generated power) of the motor generator 9 are controlled. The hybrid control unit 20 also includes motoring execution means for executing motoring that is forcibly driven by the motor generator 9 without supplying fuel to the engine 2, as will be described later.

In the EV mode (second travel mode), the engine 2 is stopped, and the front motor 4 and the rear motor 6 are driven by the electric power supplied from the drive battery 11 to travel.
In the series mode (first travel mode), the clutch 7 a of the speed reducer 7 is disconnected and the motor generator 9 is operated by the engine 2. Then, the front motor 4 and the rear motor 6 are driven to run by the electric power generated by the motor generator 9 and the electric power supplied from the driving battery 11. In the series mode, the rotation speed of the engine 2 is set to a predetermined rotation speed, and surplus power is supplied to the drive battery 11 to charge the drive battery 11.

In the parallel mode, the clutch 7 a of the speed reducer 7 is connected, and the power is mechanically transmitted from the engine 2 via the speed reducer 7 to drive the front wheels 3. Further, the front motor 4 and the rear motor 6 are driven to run by the electric power generated by operating the motor generator 9 by the engine 2 and the electric power supplied from the driving battery 11.
The hybrid control unit 20 sets the traveling mode to the parallel mode in an efficient region of the engine 2 such as a high speed region. Further, in the region excluding the parallel mode, that is, the middle / low speed region, the mode is switched between the EV mode and the series mode based on the charging rate SOC of the driving battery 11.

The hybrid control unit 20 further has a function of charging the driving battery 11 by forcibly driving the engine 2 to generate electric power when the charging rate SOC of the driving battery 11 falls below an allowable range.
FIG. 2 is a schematic configuration diagram of an intake / exhaust system of the engine 2.
As shown in FIG. 2, in the intake passage 25 of the engine 2 of the present embodiment, an air cleaner 26 that removes dust from the introduced intake air, a throttle valve 27 that controls the intake air flow rate, and an air flow sensor 28 that detects the intake air amount ( (Intake air amount detection means) is provided.

The throttle valve 27 is controlled by the engine control unit 22 and controls the intake air flow rate by adjusting the flow passage area of the intake passage 25. Specifically, the flow path area is increased as the load (required output torque) of the engine 2 is increased, and the flow path area is decreased as the load is reduced.
The exhaust passage 31 of the engine 2 is provided with a main exhaust purification catalyst 32 and a warm-up exhaust purification catalyst 33.

The main exhaust purification catalyst 32 and the warm-up exhaust purification catalyst 33 are catalysts for purifying the exhaust of the engine 2, such as a known three-way catalyst.
The main exhaust purification catalyst 32 is a large-capacity catalyst so as to mainly perform exhaust purification, and is disposed, for example, under the floor of the vehicle 1. The warm-up exhaust purification catalyst 33 is a small-capacity catalyst, and is disposed on the upstream side of the main exhaust purification catalyst 32 and in the vicinity of the engine 2. When the engine temperature of the main exhaust purification catalyst 32 is low, such as when the engine 2 is started at a low temperature, the warm-up exhaust purification catalyst 33 immediately increases the catalyst temperature due to the exhaust of the engine 2 and improves the exhaust purification performance. Can be secured.

The engine 2 is provided with an EGR device 41 (exhaust gas recirculation device). The EGR device 41 includes an EGR passage 42 (exhaust recirculation passage) that recirculates exhaust gas to the intake passage 25 and an EGR valve 43 (exhaust recirculation valve) interposed in the EGR passage 42.
The EGR passage 42 communicates the exhaust passage 31 between the engine 2 and the warm-up exhaust purification catalyst 33 and the intake passage 25 between the engine 2 and the throttle valve 27.

The EGR valve 43 is controlled by the engine control unit 22 and controls the flow rate of the exhaust gas recirculated to the intake passage 25 by adjusting the flow area of the EGR passage 42.
The intake passage 25 between the connection portion of the EGR passage 42 and the engine 2 is provided with an intake pressure sensor 44 (detection means) that detects the intake pressure Pa.

  Further, a front O2 sensor 34 for detecting the oxygen concentration (exhaust component) in the exhaust is provided in the exhaust passage 31 between the engine 2 and the warm-up exhaust purification catalyst 33. The exhaust passage 31 between the warm-up exhaust purification catalyst 33 and the main exhaust purification catalyst 32 is provided with a rear O2 sensor 35 for detecting the oxygen concentration in the exhaust. The front O2 sensor 34 and the rear O2 sensor 35 may be air-fuel ratio sensors that detect the air-fuel ratio.

The front O2 sensor 34 and the rear O2 sensor 35 output the detected oxygen concentration to the engine control unit 22 as a voltage value.
Further, the intake pressure sensor 44 outputs the detected intake pressure Pa to the engine control unit 22.
The engine control unit 22 is a control device for controlling the engine 2, and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), and the like. . The engine control unit 22 inputs detection values from various sensors such as a front O2 sensor 34, a rear O2 sensor 35, an intake pressure sensor 44, an airflow sensor 28, and a vehicle speed sensor 45 that detects the traveling speed of the vehicle 1, and the throttle valve 27, the air-fuel ratio control of the engine 2 is performed by controlling the operation of the EGR valve 43 and a fuel injection valve (not shown).

  Further, in the present embodiment, the engine control unit 22 has a failure determination function for the front O 2 sensor 34 and the rear O 2 sensor 35 and a failure determination function for the EGR valve 43. When it is determined by the failure determination function that any one of the front O2 sensor 34, the rear O2 sensor 35, and the EGR valve 43 has failed, the driver lights the warning light 36 provided in the driver's seat of the vehicle 1. Or control the fuel injection valve or the like so that the output of the engine 2 decreases.

  The failure determination of the exhaust system sensors (the front O2 sensor 34 and the rear O2 sensor 35) is performed in a state where the rotational speed of the drive shaft of the engine 2 is equal to or higher than a predetermined value and the fuel supply to the engine 2 is stopped. A failure determination is made based on the detection values of the O2 sensors 34 and 35 accompanying the stop of the fuel supply. In the parallel mode, the failure determination is performed when the fuel supply is stopped when the vehicle is decelerated. Furthermore, it is possible to determine the failure of each of the O2 sensors 34 and 35 even in the series mode.

  The failure determination of each of the O2 sensors 34 and 35 in the series mode is performed by stopping the fuel supply to the engine 2 while performing motoring for forcibly driving the engine 2 by the motor generator 9. These failure determinations can be made during engine stop motoring that is performed when shifting from the series mode to the EV mode in which the engine 2 is stopped, and during in-series motoring that is performed by interrupting the series mode.

3 and 4 are timing charts showing an embodiment of control timing of various control signals in the failure determination method in the series mode.
In this embodiment shown in FIGS. 3 and 4, each of motoring, engine low load operation, and fuel supply stop when the driving mode is switched from the series mode to the EV mode, the series mode, and the parallel mode in this order. The request timing is shown.

As shown in FIGS. 3 and 4, motoring is performed when the engine is stopped before switching from the series mode to the EV mode. In addition, during the series mode, the series mode is temporarily interrupted to perform motoring during the series. Further, in the present embodiment, during the series mode, a low load operation is performed and the failure determination of the EGR device 41 is performed.
In the present embodiment, one type of failure determination method for the front O2 sensor 34 and three types of failure determination methods for the rear O2 sensor 35 are executed at two timings: motoring during series and motoring when the engine is stopped. Specifically, the front O2 sensor response determination is executed for the front O2 sensor 34. For the rear O2 sensor 35, rear O2 sensor adhesion determination, rear O2 sensor slope determination, and rear O2 sensor response determination are performed.

The low load motoring request for failure determination shown in FIG. 3 represents the request timing and time of motoring and low load operation required in the failure determination of each exhaust system sensor and EGR valve 43. ON indicates that motoring or low load operation is requested.
Of the above four types of exhaust system sensor failure determination methods, the front O2 sensor response determination is performed both when the air-fuel ratio in the exhaust gas changes from rich to lean and when it changes from lean to rich. 34, the time when the detected value changes by a predetermined amount is measured, and it is determined whether or not the measured time is equal to or greater than the threshold value T1. Judge that there is.

The rear O2 sensor sticking determination is performed to determine a state where the detection value of the rear O2 sensor 35 is stuck, that is, not changed at all, and an operation is performed in which the air-fuel ratio in the exhaust gas changes from rich to lean and from lean to rich. When the detected value of the rear O2 sensor 35 does not change at this time, it is determined that the rear O2 sensor 35 is in a fixed state and is in failure.
The rear O2 sensor slope determination is to determine the rate of change of the detection value of the rear O2 sensor 35. This determination is made when the air-fuel ratio in the exhaust gas changes from rich to lean. In this determination, the time when the detection value of the rear O2 sensor 35 changes the predetermined change amount in the intermediate region is measured, and it is determined whether or not the measurement time is equal to or greater than the threshold value T3. Is determined that the change rate of the rear O2 sensor 35 is abnormal.

  The rear O2 sensor response determination is to determine the rate of change of the detected value including the initial response of the rear O2 sensor 35. This determination is also made when the air-fuel ratio in the exhaust gas changes from rich to lean. . In this determination, the time when the detection value of the rear O2 sensor 35 changes from the fuel supply stop to a predetermined value is measured, and it is determined whether or not the measurement time is within the threshold value T4. The response of the rear O2 sensor 35 is determined to be abnormal.

  The EGR failure determination is to determine whether the EGR valve 43 is normally operated and exhaust gas recirculation is performed. The EGR valve 43 is opened and closed, and the intake pressure Pa changes with the opening and closing operation. It is determined by whether or not. If the intake pressure Pa changes by a predetermined value P1 or more with the opening / closing operation of the EGR valve 43, it is determined to be normal, and if there is no change or a change less than the predetermined value P1, it is determined to be abnormal.

  The stoichiometric F / B continuation timer is a timer that measures whether the stoichiometric operation state continues for a predetermined time T5 in the engine 2 and the air-fuel ratio in the exhaust gas is stable. From the start of series mode or the end of series motoring By starting the measurement of the timer and prohibiting the motoring operation until the predetermined time T5 elapses and restricting the failure determination, it is possible to perform the failure determination with high accuracy.

  The motoring request time is a motoring request time required according to the motoring request of each of the failure determination methods. As described above, the rear O2 sensor response determination threshold value T4 is longer than the other determination threshold values T1 to T3. Therefore, when the rear O2 sensor response determination is performed, the motoring request time is set to Tm1, which is longer. When performing a failure determination method other than the O2 sensor response determination, the motoring request time is short and set to Tm2.

The motoring execution timer is a timer for setting a motoring execution time, starts measurement from the start of motoring, and ends motoring when the above motoring request time (Tm1 or Tm2) has elapsed.
The vehicle speed is the traveling speed of the vehicle 1 detected by the vehicle speed sensor 45. When the vehicle speed is equal to or less than the predetermined speed V1, failure determination of the exhaust system sensors 34 and 35 and the EGR valve 43 is restricted.

The in-series motoring prohibition timer shown in FIG. 4 is a timer for prohibiting the next motoring until a predetermined time T6 or T7 is measured after the completion of motoring.
The series medium / low load operation prohibition timer is a timer for prohibiting the low load operation from the start of the series operation until the measurement is performed for a predetermined time T8 (first predetermined time). The series medium and low load operation prohibition timer is a timer for prohibiting the next low load operation until the measurement is started for a predetermined time Ta (second predetermined time) after the low load operation is finished. is there. The low load operation is prohibited until the measurement is started from the start of the series operation until the predetermined time T8 is measured, or until the measurement is started from the time when the low load operation is finished and the measurement is performed for the predetermined time Ta.

The failure judgment operation request includes motoring when the engine is stopped, motoring during series, on condition that the restriction is released by the stoichiometric F / B continuation timer, series motoring prohibition timer, and series medium / low load operation prohibition timer. Indicates an operation request for low-load operation.
The fuel determination request fuel cut is turned on from the motoring request start timing input from the hybrid control unit 20 until the motoring execution timer reaches the motoring request time (Tm1 or Tm2), and the fuel supply is stopped. To do.

The HEV required combustion torque is an output torque of the engine 2 required from the hybrid control unit 20.
The EGR monitor completion determination indicates that the failure determination of the EGR valve 43 has ended, and is turned on when the failure determination ends, and is turned off when the vehicle power is turned off or when the engine 2 is stopped.
In the engine stall mode, the state where the drive shaft of the engine 2 is stopped is turned on, and the state where the drive shaft is rotating is turned off.

  In this embodiment, when the failure determination of the front O2 sensor 34 and the rear O2 sensor 35 is performed in the series mode, when the engine is stopped at the time of switching from the series mode to the EV mode, and during the motoring in the series The failure determination is possible in both cases, and among these motoring, the failure determination is performed at the time of motoring suitable for each failure determination method.

  The failure determination at the time of motoring in the series is based on the fact that the motor generator 9 forcibly drives the engine 2 while stopping the fuel supply to the engine 2 and the richness of the oxygen concentration (or air-fuel ratio) in the exhaust. When a change to lean is detected to determine whether the front O2 sensor 34 and the rear O2 sensor 35 have failed, and when the fuel supply to the engine 2 is resumed when returning from motoring to series operation, A change in the oxygen concentration (or air-fuel ratio) from lean to rich is detected, and failure determination of the front O2 sensor 34 and the rear O2 sensor 35 is performed. Thereby, in the failure determination at the time of motoring during the series, if the motoring time can be secured, all the failure determination methods described above can be executed.

In addition, failure determination during motoring when the engine is stopped is a failure determination method that is possible when the air-fuel ratio in the exhaust gas changes from rich to lean, and the slope determination and response determination of the rear O2 sensor 35 are possible. Become.
In the present embodiment, during the series motoring, the front O2 sensor response determination that cannot be determined when the engine is stopped is performed, and when the engine is stopped when switching to the EV mode, any motoring is performed. A rear O2 sensor slope determination and a rear O2 sensor response determination that can determine a failure are performed.

  The EGR failure determination of the present embodiment is performed during low load operation in which the power generation load of the motor generator 9 is reduced during the series mode. Specifically, when the EGR failure determination is performed, the generated power of the motor generator 9 is reduced, and the HEV required combustion torque is set to a second predetermined torque N2 lower than the first predetermined torque N1 that is normally set during series operation. Set. At this time, the engine rotational speed becomes a second predetermined rotational speed R2 lower than the first rotational speed R1 normally set in the series mode. During series motoring and motoring when the engine is stopped, the engine rotation speed is set to a third rotation speed R3 that is lower than the second rotation speed R2. It should be noted that the EGR failure determination in the engine control unit 22 corresponds to the failure determination means of the present invention.

As shown in FIG. 4, when the EV mode is switched to the series mode, the series medium / low load operation prohibition timer counts down from the predetermined value T8, and when it becomes 0, the vehicle speed is not less than the predetermined speed V1. A failure determination of the EGR valve 43 is performed.
The failure determination of the EGR valve 43 is performed by opening / closing the EGR valve 43 as described above, and determining whether or not the intake pressure Pa changes with the opening / closing operation. For example, three times), and it is determined that only when all change by a predetermined value P1 or more, it is normal. The EGR monitor completion determination counts the number of times that the intake pressure Pa has changed by a predetermined value P1 or more. If it is performed a predetermined number of times, it is turned on, and the EGR failure determination is completed.

Further, in the present embodiment, when the series medium / low load operation is finished in the series mode, the series medium / low load operation prohibition timer counts down from the predetermined time Ta, and when it becomes 0, the failure determination of the next EGR valve 43 is performed. Is allowed. The predetermined time Ta is a value larger than the predetermined time T8.
Therefore, in this embodiment, until the predetermined time T8 elapses after the engine is started, the first series medium / low load operation after the engine 2 is started is regulated and the first series medium / low load is regulated. Until the predetermined time Ta elapses after the operation is completed, the second series medium / low load operation is restricted. Here, since the predetermined time Ta is set to be longer than the predetermined time T8, immediately after the first EGR failure determination, the second EGR failure determination involving the series medium / low load operation is regulated.

  Thereby, even if the exhaust gas recirculated at the time of the first EGR failure determination remains in the intake passage, it is possible to prevent misfire at the time of the second EGR failure determination. This is because the intake air flow rate is reduced in the series medium / low load operation performed at the time of EGR failure determination, and the exhaust gas recirculation amount is at least easily misfired. In this embodiment, the first time from the start of the engine due to the start of the series operation. Until the predetermined time Ta, which is longer than the predetermined time T8, which is the time for regulating the middle-low load operation of the current series, is controlled, the exhaust in the intake passage 25 is sufficiently reduced by regulating the middle-low load operation of the next series. In the above, since the start of the second series medium / low load operation is permitted, it is difficult to misfire in the series medium / low load operation performed for the second EGR failure determination. On the other hand, the predetermined time T8, which is the time for regulating the first series medium / low load operation from the engine start, is smaller than the predetermined time Ta for regulating from the end of the first series medium / low load operation to the second series medium / low load operation. By setting, the first EGR failure determination can be performed at an early stage after preventing misfire in the first series medium and low load operation.

As for the EGR failure determination for the third and subsequent times after the engine 2 has started, a predetermined time Ta has elapsed since the end of the series medium / low load operation of the EGR failure determination performed before that, similar to the second EGR failure determination. Start is regulated until Thereby, misfire can be prevented also about the EGR failure determination after the 3rd time.
Further, in the series mode, the engine control unit 22 integrates the intake air amount input from the air flow sensor 28, and sets a predetermined time Ta for restricting the start of the second and subsequent series middle and low load operations at a constant value. Instead, it may be changed based on the integrated value of the intake air amount. Specifically, the intake air amount in the first series medium and low load operation is integrated, and a predetermined time Ta is set from the integrated value of the intake air amount. The relationship between the integrated value of the intake air amount and the predetermined time Ta is stored in advance in the engine control unit 22 and is set so that the predetermined time Ta decreases as the integrated value increases.

  Thus, the predetermined time Ta, which is the time during which the start of the next series medium / low load operation is restricted from the end of the series medium / low load operation, is set based on the integrated value of the intake flow rate in the series medium / low load operation. Therefore, it is possible to restrict the start of the next series medium / low load operation until the time necessary for avoiding misfires has elapsed according to the exhaust amount remaining in the intake passage 25 at the end of the series medium / low load operation. In addition, when the integrated value of the intake flow rate in the series medium / low load operation is large, that is, as the residual amount of exhaust gas at the end of the series medium / low load operation is small, the predetermined time Ta for restricting the start of the next medium / low load operation. By shortening the EGR failure determination, the start of the next series medium / low load operation can be accelerated and the EGR failure determination can be terminated promptly while avoiding misfire during the next series medium / low load operation.

  In addition, this invention is not limited to the said embodiment. For example, the hybrid control unit 20 may perform various types of failure determination, failure determination regulation, and various types of control associated with failure determination. In the present embodiment, the present invention is applied to a plug-in hybrid vehicle that can be switched between the EV mode, the series mode, and the parallel mode. However, the present invention can also be applied to a vehicle that is not a hybrid vehicle. The present invention is widely applicable to vehicles equipped with a failure determination device that performs EGR failure determination by performing low-load operation of an engine. In the case of a vehicle that is not such a hybrid vehicle, the regulation time for performing low-load operation for failure determination after the engine has started may be increased from the first time to the second time.

1 Vehicle 2 Engine (Internal combustion engine)
4 Front motor (drive motor)
6 Rear motor (drive motor)
9 Motor generator 11 Drive battery 22 Engine control unit (failure determination means, first failure determination restriction means, second failure determination restriction means)
28 Air flow sensor (Intake air quantity detection means)
42 EGR passage (exhaust gas recirculation passage)
43 EGR valve (exhaust gas recirculation valve)
44 Intake pressure sensor (detection means)

Claims (5)

An internal combustion engine that is mounted on a vehicle and includes an exhaust gas recirculation path that recirculates exhaust gas to an intake passage; and an exhaust gas recirculation valve that opens and closes the exhaust gas recirculation path.
Detecting means for detecting an intake pressure of the internal combustion engine;
A failure determination means for determining a failure of the exhaust gas recirculation valve based on a change in a detection value of the detection means when the exhaust gas recirculation valve is controlled to be opened and closed during operation of the internal combustion engine;
First failure determination restriction means for restricting the failure determination by the failure determination means for the first time from the start of the internal combustion engine until a first predetermined time has elapsed from the start;
During the operation of the internal combustion engine, until the second predetermined time has elapsed from the end of the first failure determination by the failure determination means, the second failure determination means for restricting the failure determination by the failure determination means from the start of the internal combustion engine. 2 failure determination regulation means,
The vehicle failure determination device, wherein the second predetermined time is set longer than the first predetermined time. An intake air amount detecting means for detecting an intake air amount of the internal combustion engine;
2. The vehicle according to claim 1, wherein the second predetermined time is set based on an integrated value of the intake air amount detected by the intake air amount detection means in the first failure determination. Failure determination device.   The vehicle failure determination device according to claim 2, wherein the second predetermined time is set shorter as the integrated value of the intake air amount becomes larger.   The second failure determination restricting means further restricts the failure determination by the failure determination means during the operation of the internal combustion engine until the second predetermined time elapses from the end of the failure determination immediately before the failure determination. The vehicle failure determination device according to claim 1, wherein the vehicle failure determination device is a vehicle failure determination device. The vehicle is driven by the internal combustion engine and can generate power, while a motor generator capable of driving the internal combustion engine with electric power supplied from a driving battery, and driving wheels with electric power supplied from the driving battery. A drive motor for driving,
A hybrid vehicle capable of selecting a first traveling mode in which the driving wheel is driven by the driving motor while the motor generator is driven by the internal combustion engine to generate electric power,
5. The vehicle failure determination device according to claim 1, wherein the failure determination unit performs the failure determination during the first travel mode.

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