JP6774002B2 - Hybrid vehicle failure diagnostic device - Google Patents

Description

The present invention relates to a failure diagnosis device for a hybrid vehicle, and more particularly to a failure diagnosis device for diagnosing a failure of various devices (hereinafter collectively referred to as emission emission suppression devices) that suppress emission emission into the atmosphere.

As is well known, the engine mounted on the hybrid vehicle is used to drive the driving wheels and the generator, and it is generated in the exhaust gas generated by the operation of the engine or in the fuel tank that stores the fuel of the engine. When fuel evaporative gas or the like is discharged to the outside, it leads to environmental deterioration. Therefore, in order to prevent such a situation, the vehicle is equipped with various emission emission control devices.

For example, since NOx, HC, CO, etc. are contained in the exhaust gas discharged from the engine, a catalyst device is provided in the exhaust system of the engine to purify these. In addition, since it is necessary to optimally control the exhaust air-fuel ratio of the engine in order for the catalyst device to exhibit the desired purification performance, the exhaust system of the engine has a linear air-fuel ratio sensor (hereinafter referred to as LAFS) that detects the exhaust air-fuel ratio. ) Etc. are provided, and the exhaust air-fuel ratio is controlled based on the output.

Further, in order to reduce NOx, the engine is equipped with an exhaust gas circulation device, and by circulating the exhaust gas to the intake side as exhaust gas circulation gas, the combustion temperature in the cylinder is lowered and the generation of NOx is suppressed. Furthermore, the fuel tank is equipped with a fuel evaporative emission control device for processing the fuel evaporative gas generated inside. After the fuel evaporative gas is once adsorbed on the canister, the adsorbed fuel evaporative gas is used as the engine. It is burned in the cylinder together with fuel during the operation of.

For example, when the catalyst device deteriorates, it causes the exhaust gas to pass through due to the deterioration of purification performance, and when the exhaust sensor such as LAFS deteriorates, the original performance of the catalyst device is not exhibited due to an inappropriate exhaust air-fuel ratio due to a detection error. cause. In addition, if the exhaust gas circulation device fails, the amount of NOx generated in the cylinder increases due to the inappropriate amount of exhaust gas circulation and recirculation, and if the fuel evaporative emission control device does not function normally, the fuel evaporative gas is used in the engine. Cannot be processed.

In order to detect deterioration and failure of these emission emission suppression devices (hereinafter, these are collectively referred to as failures), the vehicle is equipped with a failure diagnosis device. For example, the technique described in Patent Document 1 is known as an exhaust gas circulation failure diagnosis device for diagnosing an exhaust gas circulation failure. The vehicle described in Patent Document 1 is a hybrid vehicle, and in the series mode, which is one of the traveling modes, the motor generator is driven by the engine, and the generated power is used for driving the traveling motor and charging the traveling battery. ing.

The operating point of the engine in series mode is determined according to the target charge power to the traveling battery. While the vehicle is running, the target charge power is sequentially calculated based on the deviation between the actual SOC (charge rate: State Of Charge) of the running battery and the target SOC, and the target power generation amount of the motor generator corresponding to the target charge power is minimized. The engine is operated at the achievable operating point.
Failure diagnosis of the exhaust gas circulation device is carried out while driving in such a series mode, and the exhaust gas circulation device is based on the change in the intake manifold pressure (hereinafter referred to as the intake manifold pressure) when the exhaust gas circulation valve is opened and closed. Normal / abnormal is judged. Since the intake manifold pressure is affected by the rotation speed and load of the engine, it is necessary to determine the operating point of the engine, and from the viewpoint of diagnostic accuracy, it is desirable to have an operating point where the intake manifold pressure clearly changes as the exhaust gas circulation valve opens and closes. From this point of view, the monitor area is set in advance on the lower load side than the engine operating point in the normal series mode, and at the time of failure diagnosis, the target operating point is set in the center of the monitor area and the engine is operated. are doing. Therefore, at the time of failure diagnosis, for example, as shown in FIG. 7, the engine is operated at the operation point marked with ● in the monitor area.

Japanese Unexamined Patent Publication No. 2013-78995

By the way, the situation where the traveling battery is near full charge and does not need to be charged, or the situation where normal charging cannot be expected at extremely low temperature (both are situations where the charging power should be limited, and hereinafter, it is expressed as a time when the battery acceptability is lowered. ), The target charging power is limited to protect the running battery. However, in the exhaust gas circulation failure diagnosis device of the hybrid vehicle described in Patent Document 1, when the target charging power is limited in this way, the operating point of the engine deviates from the monitoring area and the failure diagnosis of the exhaust gas circulation device is completed. There was a problem that it could not be done.

That is, when the battery acceptability is lowered, the protection of the traveling battery is prioritized over the failure diagnosis of the exhaust gas circulation device, and as a result, the target charging power and the target power generation amount of the motor generator are limited. Then, due to the limitation of the target power generation amount, the operating point of the engine deviates from the monitor area to the low load side as shown by a circle in FIG.
For this reason, when the failure diagnosis of the exhaust gas circulation device is performed at the operation point marked with ● in the figure in the monitor area, the battery acceptability of the traveling battery deteriorates, or the battery acceptability of the traveling battery deteriorates. When the engine is being operated at the operating point marked with a circle outside the monitor area, if the conditions for performing the failure diagnosis of the exhaust gas circulation device are met, the engine control is performed to keep the operating point marked with a circle in the monitor area. Is tried, but due to the priority of battery protection, it is returned to the operation point marked with a circle outside the monitoring area. As a result, there is a problem that a hunting phenomenon that goes back and forth between the two operating points occurs, the failure diagnosis of the exhaust gas circulation device cannot be completed, and the frequency of the failure diagnosis decreases.

The above is the explanation of the failure diagnosis of the exhaust gas circulation device, but since it is necessary to determine the operating point of the engine at the time of failure diagnosis even with other emission emission suppression devices, a failure occurs within a predetermined monitor area. Diagnosis was carried out and a similar problem inevitably occurred when battery acceptability declined.
The present invention has been made to solve such a problem, and an object of the present invention is to protect the traveling battery by limiting the target charging power even when the battery acceptability of the traveling battery is lowered. It is an object of the present invention to provide a failure diagnosis device for a hybrid vehicle capable of performing a failure diagnosis of an emission emission suppression device while keeping the operating point of the engine within the monitoring area.

In order to achieve the above object, the failure diagnosis device of the hybrid vehicle of the present invention operates the engine at a predetermined operating point to drive the generator, and the charge control for charging the battery with the power generated by the generator. When the means, the battery acceptability determining means for determining whether or not the battery acceptability for which the charging power to the battery should be limited is deteriorated, and the battery acceptability determining means determine that the battery acceptability is deteriorated. In addition, a charging power limiting means for reducing the generated power by switching the operating point of the engine in the load reduction direction in order to limit the charging power to the battery, and an emission emission suppressing means for suppressing emission emission to the atmosphere. When the conditions for performing the failure diagnosis of the emission emission suppressing means are satisfied, the failure diagnosis is performed while keeping the operating point of the engine within the monitor area defined by the load and the rotation speed. When the failure diagnosis of the emission emission suppressing means is carried out by the means and the failure diagnosis means, when the operating point of the engine is switched in the load reduction direction based on the determination of the battery acceptability determination means, the monitor area is changed. in case of deviation, a monitor region growing means for keeping the operating point to expand the monitoring area in the load lowering direction to the enlarged monitored area, the emission emission control means, exhaust air-fuel ratio of the engine The failure diagnosis means forcibly vibrates the exhaust air-fuel ratio of the engine between the rich side and the lean side, diagnoses deterioration based on the output change of the exhaust sensor, and diagnoses deterioration. When the monitor area is expanded by the monitor area expanding means, the period or amplitude of the forced excitation is increased as compared with the normal time in order to compensate for the deterioration of the followability of the output of the exhaust sensor due to the decrease in the exhaust gas flow rate of the engine. It is characterized by increasing at least one (claim 1).

According to the exhaust gas circulation failure diagnosis device of the hybrid vehicle configured in this way, when the failure judgment of the emission emission suppressing means is performed by the failure diagnosis means, the operating point of the engine is loaded based on the judgment of the battery acceptability judgment means. If the monitor area deviates from the monitor area when switched in the downward direction, the monitor area is expanded in the load decrease direction, so that the operating point of the engine is kept within the monitor area while limiting the charging power for battery protection. Therefore, it becomes possible to carry out failure diagnosis of the emission suppression means.
Further, when the monitor area is expanded in the load reduction direction, the exhaust gas flow rate of the engine decreases, the followability of the output of the exhaust sensor deteriorates, and there is a possibility that a normal failure diagnosis cannot be expected. In the present invention, at this time, at least one of the period and the amplitude of the forced excitation of the exhaust air-fuel ratio is increased as compared with the normal time, so that the followability of the output of the exhaust sensor is deteriorated. However, it is possible to accurately perform failure diagnosis based on clear output changes.

As another aspect, it is preferable that the emission emission suppressing means is an exhaust sensor that detects the exhaust air-fuel ratio of the engine, and the failure diagnosis means diagnoses the deterioration of the exhaust sensor (claim 2 ).
According to this aspect, it is possible to perform deterioration diagnosis of the exhaust sensor while keeping the operating point of the engine within the monitor area while limiting the charging power for battery protection.

As another aspect, it is preferable that the emission emission suppressing means is a catalyst device that purifies the exhaust gas of the engine, and the failure diagnosis means diagnoses the deterioration of the catalyst device (claim 3 ).
According to this aspect, deterioration diagnosis of the catalyst device can be performed while keeping the operating point of the engine within the monitor area while limiting the charging power for battery protection.

As another aspect, the emission emission suppressing means is a fuel evaporation gas emission suppressing device for processing fuel evaporative gas generated in a fuel tank for storing fuel of the engine, and the failure diagnosis means is the fuel evaporative gas. It is preferable to diagnose the failure of the emission control device (claim 4 ).
According to this aspect, it is possible to perform a failure diagnosis of the fuel evaporative emission suppression device while keeping the operating point of the engine within the monitoring area while limiting the charging power for battery protection.

As another embodiment, the emission emission suppressing means adsorbs the fuel evaporative gas generated in the fuel tank for storing the fuel of the engine to the canister, and the adsorbed fuel evaporative gas is negative pressure on the intake side of the engine. It is a fuel evaporative emission suppression device that is transferred to the intake side and burned by utilizing the above, and the failure diagnosis means opens and closes a purge valve provided between the canister and the intake side of the engine. Based on the pressure change in the canister at that time, the failure of the fuel evaporative emission suppression device is diagnosed, and when the monitor area is expanded by the monitor area expansion means, the purge flow rate due to the decrease in the exhaust gas flow rate of the engine In order to compensate for the decrease, it is preferable to carry out at least one of extending the valve opening time of the purge valve as compared with the normal time and applying a small value as a failure determination value for determining the pressure change ( Claim 5 ).

According to this aspect, when the monitor area is expanded in the load decreasing direction, the negative pressure on the intake side of the engine decreases, the pressure change in the canister becomes small, and there is a possibility that a normal failure diagnosis cannot be expected. In the present invention, at this time, the opening time of the purge valve is extended as compared with the normal time, or a small value is applied as a failure determination value for determining the pressure change, so that the increase in the differential pressure is slow. Even so, it is possible to accurately perform failure diagnosis.

According to the exhaust gas circulation failure diagnosis device of the hybrid vehicle of the present invention, the operating point of the engine is kept within the monitoring area while protecting the traveling battery by limiting the target charging power even when the battery acceptability of the traveling battery deteriorates. It is possible to carry out a failure diagnosis of the exhaust gas circulation device.

It is an overall block diagram which shows the plug-in hybrid vehicle to which the failure diagnosis apparatus of embodiment is applied. It is a block diagram which shows the exhaust gas circulation device, the catalyst device, and exhaust sensors mounted on an engine. It is a time chart which shows the implementation status of the deterioration diagnosis of LAFS. It is a time chart which shows the implementation status of the deterioration diagnosis of a catalyst device. It is a block diagram which shows the fuel evaporative emission suppression device. It is a block diagram which shows the evaporative leak check module. It is a map which shows the operating point of the engine in the monitor area at the time of failure diagnosis by the 1st method of 1st Embodiment. It is a time chart which shows the implementation situation when the first method is applied to the failure diagnosis of LAFS. It is a time chart which shows the implementation situation when the first method is applied to the failure diagnosis of the fuel evaporative emission control device. It is a time chart which shows the implementation situation when the first method is applied to the failure diagnosis of an exhaust gas circulation device. It is a time chart which shows the implementation situation when the 2nd method is applied to the failure diagnosis of LAFS. It is a time chart which shows the implementation situation when the 2nd method is applied to the failure diagnosis of the fuel evaporative emission suppression device. It is a time chart which shows the implementation situation when the 2nd method is applied to the failure diagnosis of the exhaust gas circulation device.

Hereinafter, an embodiment in which the present invention is embodied in a failure diagnosis device for a plug-in hybrid vehicle (hereinafter referred to as vehicle 1) will be described.
FIG. 1 is an overall configuration diagram showing a plug-in hybrid vehicle to which the failure diagnosis device of the present embodiment is applied.
The vehicle 1 of the present embodiment is a four-wheel drive vehicle configured to drive the front wheels 4 by the output of the front motor 2 or the outputs of the front motor 2 and the engine 3, and drive the rear wheels 6 by the output of the rear motor 5. is there.

The output shaft of the engine 3 is connected to the drive shaft 8 of the front wheels 4 via the speed reducer 7, and the speed reducer 7 has a built-in clutch 9 capable of connecting and disconnecting internal power transmission. When the clutch 9 is connected, the driving force of the engine 3 is transmitted to the front wheels 4 via the speed reducer 7 and the drive shaft 8, and when the clutch 9 is disengaged, the engine 3 is disconnected from the front wheels 4 side and can be operated independently.
A front motor 2 is connected to the downstream side (front wheel 4 side) in the power transmission direction from the clutch 9 of the speed reducer 7, and the driving force thereof is transmitted from the speed reducer 7 to the front wheels 4 via the drive shaft 8. There is. Further, a motor generator 10 is connected to the upstream side (anti-front wheel 4 side) in the power transmission direction from the clutch 9 of the speed reducer 7, and when the clutch 9 is disengaged, the motor generator 10 generates electricity by driving the engine 3. Alternatively, it functions as a starter motor for starting the engine 3. Further, the rear motor 5 is connected to the drive shaft 12 of the rear wheels 6 via the speed reducer 11, and the driving force thereof is transmitted from the speed reducer 11 to the rear wheels 6 via the drive shaft 12.

An engine controller 14 composed of an input / output device, a storage device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), and the like is connected to the engine 3, and the throttle of the engine 3 is connected by the engine controller 14. The engine 3 is operated by controlling the opening degree, the fuel injection amount, the ignition timing, and the like.
The front motor 2, the rear motor 5, and the motor generator 10 are three-phase AC electric motors, and a traveling battery 15 (battery) is provided as a power source for them. The traveling battery 15 is composed of a secondary battery such as a lithium ion battery, and has a built-in battery monitoring unit 15a that calculates its SOC (charge rate) and detects the temperature TBAT.

The front motor 2 and the motor generator 10 are connected to the traveling battery 15 via the front motor controller 16, and the front motor controller 16 is provided with a front motor inverter 16a and a motor generator inverter 16b. The DC power of the traveling battery 15 is converted into three-phase AC power by the front motor inverter 16a and the motor generator inverter 16b and supplied to the front motor 2 and the motor generator 10. Further, the regenerated electric power by the front motor 2 and the generated electric power by the motor generator 10 are converted into DC electric power by the front motor inverter 16a and the motor generator inverter 16b, and the traveling battery 15 is charged.

Similarly, the rear motor 5 is connected to the traveling battery 15 via the rear motor controller 17, and the rear motor controller 17 is provided with a rear motor inverter 17a. The DC power of the traveling battery 15 is converted into three-phase AC power by the rear motor inverter 17a and supplied to the rear motor 5, and the regenerated power by the rear motor 5 is converted into DC power by the rear motor inverter 17a and charged to the traveling battery 15. Will be done.

Further, the vehicle 1 is provided with a charger 13 that charges the traveling battery 15 with an external power source.
The hybrid controller 18 is a control device for performing comprehensive control of the vehicle 1, and is composed of an input / output device, a storage device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), and the like. There is. The hybrid controller 18 controls the operating states of the engine 3, the front motor 2, the motor generator 10, the rear motor 5, the disengagement state of the clutch 9 of the speed reducer 7, and the like. Therefore, on the input side of the hybrid controller 18, the battery monitoring unit 15a of the traveling battery 15, the front motor controller 16, the rear motor controller 17, the engine controller 14, the accelerator opening sensor 19 for detecting the accelerator opening θacc, and the vehicle speed A vehicle speed sensor 20 that detects V is connected, and detection and operation information from these devices is input.

Further, a front motor controller 16, a rear motor controller 17, a clutch 9 of the speed reducer 7, and an engine controller 14 are connected to the output side of the hybrid controller 18.
Then, the hybrid controller 18 switches the traveling mode of the vehicle 1 between the EV mode, the series mode, and the parallel mode based on the various detection amounts and operation information of the accelerator opening sensor 19 and the like. For example, in a region where the efficiency of the engine 3 is high, such as a high-speed region, the traveling mode is set to the parallel mode. Further, in the medium-low speed region, the EV mode and the series mode are switched based on the charge rate SOC of the traveling battery 15.

In the EV mode, the clutch 9 of the speed reducer 7 is disengaged, the engine 3 is stopped, and the front motor 2 and the rear motor 5 are driven by the electric power from the traveling battery 15 to drive the vehicle 1.
In the series mode, after disengaging the clutch 9 of the speed reducer 7, the engine 3 is operated to drive the motor generator 10, and the front motor 2 and the rear motor 5 are driven by the generated power and the power from the traveling battery 15. The vehicle 1 is driven and the traveling battery 15 is charged with surplus electric power.

In the parallel mode, after connecting the clutch 9 of the reducer 7, the engine 3 is operated to transmit the driving force from the reducer 7 to the front wheels 4, and when there is a surplus in the engine driving force, the front motor 2 regenerates the engine. However, when the engine driving force is insufficient, the front motor 2 assists using the battery power.
Further, the hybrid controller 18 calculates the total required output required for traveling of the vehicle 1 based on the various detected amounts and operation information, and calculates the total required output on the front motor 2 side and the rear motor 5 side in the EV mode and the series mode. In the parallel mode, it is distributed to the front motor 2 side, the engine 3 side, and the rear motor 5 side. Then, the required output distributed to each, the gear ratio of the reduction gear 7 from the front motor 2 to the front wheels 4, the gear ratio of the reduction gear 7 from the engine 3 to the front wheels 4, and the reduction gear 11 from the rear motor 5 to the rear wheels 6 The required torques of the front motor 2, the engine 3, and the rear motor 5 are set based on the gear ratios of the above, and command signals are output to the front motor controller 16, the rear motor controller 17, and the engine controller 14 so as to achieve each required torque. To do.

The front motor controller 16 and the rear motor controller 17 calculate a target current value to be passed through the coils of each phase of the front motor 2 and the rear motor 5 in order to achieve the required torque based on the command signal from the hybrid controller 18. Then, the front motor inverter 16a and the rear motor inverter 17a are switched and controlled based on these target current values to achieve the required torques for each. The same applies to the power generation of the motor generator 10, and the required torque is achieved by switching control of the motor generator inverter 16b based on the target current value obtained from the required torque on the negative side.

The engine controller 14 calculates target values such as throttle opening, fuel injection amount, and ignition timing for achieving the required torque based on the command signal from the hybrid controller 18, and controls the engine 3 based on those target values. Drive to achieve the required torque.
Further, the hybrid controller 18 controls the operating point of the engine 3 driving the motor generator 10 in order to optimize the charging state of the traveling battery 15 while the vehicle 1 is traveling in the series mode. Specifically, the target charging power is sequentially calculated based on the deviation between the actual SOC of the traveling battery 15 and the target SOC, and the operating point at which the target power generation amount of the motor generator 10 corresponding to the target charging power can be achieved with the minimum fuel consumption is determined. Find and drive the engine 3 at that operating point. Generally speaking, as the SOC of the traveling battery 15 increases and the battery approaches full charge, the target charging power decreases, and the operating point of the engine 3 shifts to the low load side (charge control means).

In addition, the hybrid controller 18 constantly monitors the deterioration of the battery acceptability of the traveling battery 15 (a situation in which charging is not required near full charge or a situation in which normal charging cannot be expected at extremely low temperatures) (battery acceptance). (Sexity determination means), when it is determined that the battery acceptability is lowered, a process of limiting the target charging current is performed to protect the traveling battery 15 (charging power limiting means).

For example, when the following conditions 1) and 2) are satisfied, it is determined that the battery acceptability of the traveling battery 15 has deteriorated.
1) Maximum charge power-Target charge power ≤ Power limit judgment value (for example, 10 kW)
2) Charging current> current limit judgment value or battery voltage> limit voltage judgment value Here, the maximum charging power is charged by the current running battery 15 determined by the SOH (deterioration index: State of Health) and temperature of the running battery 15. The maximum power that can be used.

When the determination of the decrease in battery acceptability is made, the hybrid controller 18 limits the target charging power to the traveling battery 15. Since the target power generation amount of the motor generator 10 inevitably decreases, the operating point of the engine 3 is switched to the low load side on the engine control side.
On the other hand, in order to prevent exhaust gas generated during the operation of the engine 3 and evaporative gas generated in the fuel tank for storing the fuel of the engine 3 to the outside, the vehicle 1 has various emission suppression devices. (Emission emission suppression means) is installed, and each of these emission emission suppression devices is equipped with a failure diagnosis device for diagnosing a failure.

For example, as shown in FIG. 2, the exhaust system of the engine 3 is provided with a catalyst device 21 and exhaust sensors 22 and 23, and the intake system of the engine 3 is provided with an exhaust gas circulation device 24.
The catalyst device 21 is interposed in the exhaust passage 25 of the engine 3, and LAFS22 (linear air-fuel ratio sensor, exhaust sensor of the present invention) is provided on the upstream side of the catalyst device 21 on the exhaust passage 25. An O ₂ sensor 23 is provided on the downstream side of the. For example, the catalyst device 21 is configured as a three-way catalyst and has a function of purifying NOx, HC, and CO contained in the exhaust gas, and in order to maintain the exhaust air-fuel ratio in a stoichiometric state where the purification performance is maximized, the LAFS 22 And the operating state of the engine 3 is controlled by the hybrid controller 18 based on the output of the O ₂ sensor 23.

Since these catalyst devices 21, LAFS 22, and O ₂ sensor 23 are constantly exposed to high-temperature exhaust gas, they gradually deteriorate and deteriorate in function. The deterioration of the catalyst device 21 causes the exhaust gas to pass through due to the deterioration of the purification performance, and the deterioration of the LAFS 22 and the O ₂ sensor 23 causes the exhaust air-fuel ratio to deviate from the stoichiometric value due to improper engine control due to the detection error. It causes a situation in which the original performance of the device 21 is not exhibited.

Therefore, for example, deterioration diagnosis of the LAFS 22 and the catalyst device 21 is carried out by the hybrid controller 18 in the following procedure (fault diagnosis means).
FIG. 3 is a time chart showing the implementation status of deterioration diagnosis of LAFS 22, and the hybrid controller 18 forcibly vibrates the exhaust air-fuel ratio of the engine 3 at a predetermined period and amplitude centering on stoichiometric vibration. When the LAFS 22 is normal, the output of the LAFS 22 changes significantly in synchronization with the fluctuation of the exhaust air-fuel ratio as shown by the solid line in the figure. Therefore, when the output changes to the rich side, it exceeds the preset rich determination value Sr1, and when it changes to the lean side, it exceeds the preset lean determination value Sl1. On the other hand, when LAFS22 deteriorates, the output change of LAFS22 is reduced as shown by the broken line in the figure. Therefore, even if it changes to the rich and lean side, it does not exceed the rich determination value Sr1 and the lean determination value Sl1.

FIG. 4 is a time chart showing the implementation status of the deterioration diagnosis of the catalyst device 21, and the hybrid controller 18 forcibly vibrates the exhaust air-fuel ratio of the engine 3 at a predetermined period and amplitude centering on the stoichiometric. O ₂ storage output LAFS22 upstream of the catalytic converter 21 while greatly changed in synchronization with the fluctuation of the exhaust air-fuel ratio, the output of the downstream side of the O ₂ sensor 23, which decreases with purifying capability of the catalytic converter 21 It will change according to the ability. Specifically, when the catalyst device 21 is normal, as shown by a broken line in the figure, it changes periodically between both judgment values Sr2 and Sl2 without exceeding the preset rich judgment value Sr2 and judgment value Sl2. When the catalyst device 21 deteriorates, as shown by a solid line in the figure, the catalyst device 21 exceeds the rich determination value Sr2 and changes to the rich side, and exceeds the determination value Sl2 and changes to the lean side.

Therefore, for example, during a predetermined diagnosis period, the number of times that the output of the LAFS 22 and the output 23 of the O ₂ sensor exceed the rich judgment values Sr1 and Sr2 and the lean judgment values Sl1 and Sl2 is counted, and forced excitation is performed during the diagnosis period. Obtain the ratio between the number of fluctuations in the exhaust air-fuel ratio and the count value. As for LAFS22, the ratio approaches 0 as the deterioration progresses, and for the catalyst device 21, the ratio approaches 1 as the deterioration progresses. Therefore, by comparing these ratios with the preset count determination values, each is normal. -Judge deterioration.

Further, as shown in FIG. 2, the exhaust gas circulation device 24 adjusts the opening degree of the exhaust gas circulation passage 29 connecting the exhaust manifold 27 of the engine 3 and the intake manifold 28 (intake side) and the exhaust gas circulation passage 29. It is composed of a valve 30. The opening degree of the exhaust gas circulation valve 30 is controlled by the hybrid controller 18 based on the operating region of the engine 3, and the exhaust gas is returned to the intake manifold 28 as the exhaust gas circulation gas through the exhaust gas circulation passage 29 according to the opening degree of the exhaust gas circulation valve 30. As a result, the combustion temperature in the cylinder is lowered and the generation of NOx is suppressed.

If the desired exhaust gas circulation return amount cannot be achieved due to a failure of the exhaust gas circulation device 24, NOx increases and drivability deteriorates. Therefore, for example, the failure diagnosis of the exhaust gas circulation device 24 is carried out by the hybrid controller 18 in the following procedure (fault diagnosis means).
An intake pressure sensor 31 is provided on the intake manifold 28, and the pressure inside the intake manifold (hereinafter referred to as an intake manifold pressure) is detected by the intake pressure sensor 31. First, the hybrid controller 18 temporarily fully closes (0%) the exhaust gas circulation valve 30 and then stores the detected value of the intake manifold pressure detected by the intake pressure sensor 31 as the first intake manifold pressure Pin1. After that, the exhaust gas circulation valve 30 is set to a predetermined amount (20%), and the detected value of the intake manifold pressure is stored as the second intake manifold pressure Pin2. When the differential pressure ΔPin of the first and second intake manifold pressures Pin1 and Pin2 is equal to or higher than the preset failure determination value, the exhaust gas circulation device 24 is normally determined, and when it is less than the failure determination value, an abnormality determination is made.

On the other hand, as shown in FIG. 5, the fuel tank 33 mounted on the vehicle 1 is provided with a fuel filler port 34 for refueling, and the fuel stored in the fuel tank 33 is fueled by the fuel pump 35. It is supplied to the fuel injection valve 37 of the engine 3 via 36. A fuel evaporative emission suppression device 38 as described below is provided between the fuel tank 33 and the intake manifold 28 of the engine 3 configured in this way.

A cut-off valve 39 for preventing the outflow of fuel is provided in the fuel tank 33, and this cut-off valve 39 is connected to one end of the vapor pipe 41 via a leveling valve 40 for adjusting the liquid level at the time of refueling. ing. The vapor pipe 41 extends out of the fuel tank 33 and is interposed with a closed valve 42, and the other end of the vapor pipe 41 is connected to an intermediate portion of the purge pipe 43. One end of the purge pipe 43 is connected to the canister 44, and a bypass valve 45 is interposed between the one end and the connection point of the vapor pipe 41. The other end of the purge pipe 43 is connected to the intake manifold 28 of the engine 3, and a purge valve 46 is interposed on the purge pipe 43.

Activated carbon capable of adsorbing fuel evaporative gas is sealed inside the canister 44, and an evaporative leak check module 47 is provided on one side of the outside. As shown in FIG. 6, in the vaporizable leak check module 47, a canister side passage 47a communicating with the inside of the canister 44 and an atmosphere side passage 47b communicating with the outside are formed, and a negative pressure pump is formed in the atmosphere side passage 47b. A pump passage 47f equipped with 47c and a canister pressure sensor 47d communicates with each other.

A switching valve 47g is interposed between the canister side passage 47a, the atmosphere side passage 47b, and the pump passage 47f, and the canister side passage 47a communicates with the atmosphere side passage 47b or the pump passage 47f according to the switching of the switching valve 47g. Then, the inside of the canister 44 is opened to the atmosphere through the canister side passage 47a when communicating with the atmosphere side passage 47b, and the inside of the canister 44 is closed when communicating with the pump passage 47f. Further, regardless of the switching of the switching valve 47g, the canister pressure sensor 47d communicates with the canister 44 side via the orifice 47e of the bypass passage 47h and detects the pressure in the canister 44.

When refueling, the closed valve 42, the bypass valve 45 and the switching valve 47 g are opened, the purge valve 46 is closed, and the fuel evaporative gas in the fuel tank 33 is guided into the canister 44 and adsorbed on the activated carbon. Then, when the operation of the engine 3 is started, the closed valve 42 is closed, the switching valve 47 g and the purge valve 46 are opened, and the fuel evaporative gas adsorbed on the activated carbon of the canister 44 is negatively generated in the intake manifold 28 of the engine 3. It is guided into the intake manifold 28 through the purge pipe 43 by pressure and burned in the cylinder together with the fuel.

In order to process such fuel evaporative gas, it is necessary to normally switch the valves of the fuel evaporative emission control device 38 and transfer the fuel evaporative gas to the intake manifold 28, so that a normal function can be obtained. If not, it causes the fuel evaporative gas to leak to the outside. Therefore, a failure diagnosis (so-called purge flow monitor) of the fuel evaporative emission suppression device 38 is performed by the hybrid controller 18 in the following procedure (fault diagnosis means).

When the operation of the engine 3 is started, the hybrid controller 18 opens the bypass valve 45, closes the switching valve 47 g, the closed valve 42 and the purge valve 46, and then the pressure in the canister 44 detected by the canister pressure sensor 47d. The detected value is stored as the first canister pressure Pcan1. After that, the purge valve 46 is opened, and the detected value of the pressure in the canister 44 after a predetermined time is stored as the second canister pressure Pcan2. When the differential pressure ΔPcan of the first and second canister pressures Pcan1 and Pcan2 is equal to or higher than the preset failure determination value, the fuel evaporates as if the pressure inside the canister 44 is lowered due to the negative pressure of the intake manifold 28. The normal judgment of the gas emission suppression device is made, and if it is less than the failure judgment value, the abnormality judgment is made.

The content of the failure diagnosis of the LAFS 22, the catalyst device 21, the exhaust gas circulation device 24, and the fuel evaporative emission suppression device 38 is not limited to the above, and other methods may be used.
Then, each of the above failure diagnoses is carried out when the vehicle 1 is traveling in the series mode, and the operating point of the engine 3 defined by the rotation speed Ne of the engine 3 and the load (filling efficiency Ec or intake amount Q) is determined. The value in the normal state based on the target charging power to the traveling battery 15 is switched to a value within a predetermined monitor area suitable for each failure diagnosis. However, as described in [Problems to be Solved by the Invention], when the battery acceptability is lowered, the protection of the traveling battery 15 is prioritized over the failure diagnosis, and as a result, the operating point of the engine 3 has a low load from the monitoring area. There was a problem that the failure diagnosis could not be completed because it deviated to the side.

In view of such a defect, the present inventor has found the following two measures in order to complete the failure diagnosis of the emission emission suppression device while limiting the target charging power for the protection of the traveling battery 15.
One is a method that enables failure diagnosis by optimizing the operating point of the engine 3 and keeping it within the monitor area (hereinafter referred to as the first method), and the other is the monitor area. This is a method (hereinafter referred to as a second method) that enables failure diagnosis by enlarging and keeping the operating point of the engine 3 within the monitor area.

Hereinafter, an embodiment in which the first method is applied to each emission suppression device (LAFS 22, fuel evaporative emission suppression device 38, and exhaust gas circulation device 24) is the first embodiment, and the second method is each emission emission suppression device. The embodiments applied to the above will be sequentially described as the second embodiment.
[First Embodiment]
FIG. 7 is a map showing the operating points of the engine 3 in the monitor area at the time of failure diagnosis by the first method of the present embodiment.

The amount of power generated by the motor generator 10 is basically determined by the product of the rotation speed Ne of the engine 3 and the filling efficiency Ec or the intake amount Q. Therefore, for example, the power generation amount of the motor generator 10 is represented as shown in the characteristic lines of 30 kW and 20 kW shown in FIG. 7, and the corresponding power generation amount is achieved at any operating point on these characteristic lines. To. Then, for example, when the target power generation amount of the motor generator 10 is limited from 30 kW to 20 kW based on the decrease in battery acceptability, there is almost no room for the monitor area in the direction of decrease in load (filling efficiency Ec, intake Q). On the other hand, it can be seen that there is some room in the downward direction of the rotation speed Ne. Therefore, the present embodiment employs a method of switching the operating point of the engine 3 in the rotation decreasing direction instead of the load decreasing direction.

Therefore, according to the present embodiment, when the failure diagnosis of the emission emission suppression device is performed at the operation point marked with ● in the figure in the monitor area, the motor generator 10 is affected by the deterioration of the battery acceptability of the traveling battery 15. In order to limit the target power generation amount from 30 kW to 20 kW, if the operating point of the engine 3 is switched in the load reduction direction and the monitor area deviates, the engine 3 rotates while maintaining the current filling efficiency Ec and intake amount Q. Decrease the speed Ne and switch the operating point to the □ mark in the figure (operating point correction means).

Further, when the engine 3 is being operated at the operating point marked with a circle in the figure in order to limit the target power generation amount of the motor generator 10 to 20 kW due to the deterioration of the battery acceptability of the traveling battery 15, the emission emission suppression device When the conditions for performing the failure diagnosis (for example, the throttle opening is constant, the cooling water temperature is within the predetermined range, etc.) are satisfied, the characteristics of 20 kW are increased while increasing the filling efficiency Ec and the intake amount Q of the engine 3 and decreasing the rotation speed Ne. Move the operating point of the engine 3 to the □ mark on the line (operating point correction means).

FIG. 8 is a time chart showing an implementation status when the first method is applied to the failure diagnosis of LAFS22.
The monitor area for fault diagnosis of LAFS22 is preset to, for example, the rotation speed Ne1250 to 1750 rpm of the engine 3 and the filling efficiency Ec30 to 50%, and the central rotation speed Ne1500 rpm and the filling efficiency Ec40% are the target operations at the time of fault diagnosis. It is set as a point.

In the normal state where the battery acceptability of the traveling battery 15 is not deteriorated, the engine 3 is operated at an operating point where the target power generation amount of the motor generator 10 can be achieved with the minimum fuel consumption, as shown by the solid line in the figure. .. When the conditions for performing the failure diagnosis are satisfied and then the conditions for forced excitation are satisfied, the operating point of the engine 3 is switched to the target operating point in the monitor area in response, and the forced excitation of the exhaust air-fuel ratio is performed. To be started. Since the motor generator 10 is not restricted in power generation, the engine 3 is operated at the target operating point and is kept in the monitor area, and the failure diagnosis is performed based on the output of the LAFS 22.

On the other hand, when the battery acceptability decreases, as shown by the broken line in the figure, the operating point of the engine 3 falls below the lower limit filling efficiency Ec of the monitor area due to the power generation limitation of the motor generator 10, so that the monitor area is normally used. Failure diagnosis is not started because it is considered to be deviating. In the present embodiment, when the execution condition of the failure diagnosis of LAFS22 is satisfied, the rotation speed Ne decreases in the monitor area, the filling efficiency Ec increases, and the area moves into the monitor area. Therefore, even in this case, the operating point of the engine 3 is kept within the monitor area, and the failure diagnosis of the LAFS 22 is performed without any problem.

The failure diagnosis of the catalyst device 21 can also be performed by the same procedure as in the case of LAFS 22.
FIG. 9 is a time chart showing an implementation status when the first method is applied to the failure diagnosis of the fuel evaporative emission control device 38.
The intake amount Q is used instead of the filling efficiency Ec for the monitor area for failure diagnosis of the fuel evaporative emission suppression device 38, and the monitor area is defined by the rotation speed Ne and the intake amount Q of the engine 3, and the failure is in the center thereof. The target operating point at the time of diagnosis is set.

Therefore, in a state where the battery acceptability is lowered, the operating point of the engine 3 is lower than the lower limit intake amount Q of the monitor area due to the power generation limitation of the motor generator 10, and therefore it is normally considered to deviate from the monitor area. The failure diagnosis is not started. In the present embodiment, when the execution condition of the failure diagnosis of the fuel evaporative emission suppression device 38 is satisfied, the rotation speed Ne decreases in the monitor area and the intake amount outside the monitor area is reduced as shown by the broken line in FIG. Q increases and moves into the monitor area. Therefore, even in this case, the operating point of the engine 3 is kept within the monitor area, and the failure diagnosis is performed without any problem.

FIG. 10 is a time chart showing an implementation status when the first method is applied to the failure diagnosis of the exhaust gas circulation device.
The monitoring area for failure diagnosis of the exhaust gas circulation device 24 is preset to, for example, the rotation speed Ne1250 to 1750 rpm and the filling efficiency Ec15 to 25% of the engine 3, and the central rotation speed Ne1500 rpm and the filling efficiency Ec20% are set at the time of failure diagnosis. It is set as the target driving point of.

In this case, the control status of the operating point of the engine 3 during normal operation and when the battery acceptability is lowered is the same as the failure diagnosis of LAFS 22 described above except that the setting of the monitor area is different. Therefore, although not duplicated, the operating point of the engine 3 is kept within the monitor area due to the decrease in the rotation speed Ne and the increase in the filling efficiency Ec even when the battery acceptability is lowered, and the exhaust gas circulation device has no problem. Twenty-four failure diagnoses are carried out.

As described above, if the first method according to the present embodiment is applied to any of the emission suppression devices, the traveling battery 15 can be protected by limiting the target charging power even when the battery acceptability of the traveling battery 15 deteriorates. , The operating point of the engine 3 can be kept within the monitor area to perform the failure diagnosis.
It goes without saying that the above-mentioned examples of the filling efficiency Ec and the rotation speed Ne of the engine 3 are merely examples and can be arbitrarily changed.
[Second Embodiment]
As described above, the monitor area is defined by the rotation speed Ne of the engine 3 and the filling efficiency Ec or the intake amount Q, and the operating point of the engine 3 is the filling efficiency Ec or the intake amount due to the limitation of the target power generation amount of the motor generator 10. If it falls below the lower limit of Q, the failure diagnosis cannot be performed. Therefore, only when the battery acceptability of the traveling battery 15 is lowered, the monitor area is expanded in the load lowering direction, and more specifically, the lower limit of the filling efficiency Ec or the intake amount Q of the monitor area is lowered to operate the engine 3. In the present embodiment, a method of keeping the points in the monitor area without switching is adopted (monitor area expansion means).

FIG. 11 is a time chart showing an implementation status when the second method is applied to the failure diagnosis of LAFS22.
As shown by the solid line in the figure, the control state in the normal state in which the battery acceptability of the traveling battery 15 is not deteriorated is the same as that of the first embodiment described above, and the LAFS 22 is operated while the engine 3 is operated at the target operating point. Failure diagnosis is carried out based on the output of.

On the other hand, when the battery acceptability deteriorates, the operation point of the engine 3 falls below the lower limit filling efficiency Ec of the monitor region due to the power generation limitation of the motor generator 10, so that the failure diagnosis is not started. In the present embodiment, when the execution condition of the failure diagnosis of LAFS22 is satisfied, the lower limit of the monitor area is switched in the direction of lowering the filling efficiency Ec as shown by the virtual line in FIG. 7, and the load of the monitor area is reduced accordingly. It is expanded in the direction (monitor area expansion means). Therefore, as shown by the broken line in FIG. 11, the operating point of the engine 3 that has deviated from the monitor area is maintained in the monitor area, and the failure diagnosis is started without any problem.

Then, in the failure diagnosis when the battery acceptability is lowered, forced vibration different from the normal time is performed, and the purpose thereof is as described below.
As is well known, there is a correlation between the followability of the output of the LAFS 22 and the exhaust gas flow rate of the engine 3, and the exhaust gas flow rate changes according to the filling efficiency Ec of the engine 3. More specifically, when the filling efficiency Ec of the engine 3 decreases, the exhaust gas flow rate decreases, and the followability of the output of the LAFS 22 gradually deteriorates accordingly. Therefore, when the failure diagnosis is performed with the filling efficiency Ec of the engine 3 lowered to the lower limit of the monitor area, the followability of the output of the LAFS 22 deteriorates most, and even in this case, the failure diagnosis is possible. The period and amplitude of the forced excitation are set so that the output change of the LAFS 22 can be obtained. In the second method according to the present embodiment, the lower limit of the monitor area, which has almost no margin for the output followability of the LAFS 22, is further switched in the direction of lowering the filling efficiency Ec, so that a normal failure occurs due to deterioration of the output followability. There is a possibility that the diagnosis cannot be expected.

Therefore, in the present embodiment, as can be seen from the comparison with FIG. 8, the cycle of forced excitation of the exhaust air-fuel ratio is increased at the time of failure diagnosis when the battery acceptability to which the second method is applied is deteriorated. There is. Therefore, the decrease in the filling efficiency Ec is compensated, and even in a situation where the followability of the output of the LAFS 22 is deteriorated, the failure diagnosis can be accurately performed based on the clear change in the output of the LAFS 22.

Although not shown in FIG. 11, the time required for failure diagnosis is extended as the cycle increases. Further, instead of increasing the forced vibration cycle, the forced vibration amplitude may be increased, or both the forced vibration cycle and the amplitude may be increased.
Further, the failure diagnosis of the catalyst device 21 can be performed in the same manner as in the case of LAFS 22, and the same applies to the point of increasing the period and amplitude of the forced excitation at that time.

FIG. 12 is a time chart showing an implementation status when the second method is applied to the failure diagnosis of the fuel evaporative emission control device 38.
As described in the first embodiment, the intake amount Q is used instead of the filling efficiency Ec in the monitor area for failure diagnosis of the fuel evaporative emission suppression device 38. Therefore, in a state where the battery acceptability is lowered, the operating point of the engine 3 is lower than the lower limit intake amount Q of the monitor area due to the power generation limitation of the motor generator 10, and therefore it is normally considered to deviate from the monitor area. The failure diagnosis is not started. In the present embodiment, when the execution condition of the failure diagnosis is satisfied, the lower limit of the monitor area is switched in the downward direction of the intake air amount Q and expanded, so that the monitor area deviates from the monitor area as shown by the broken line in the figure. The operating point of the engine 3 that has been used is maintained in the monitor area, and the failure diagnosis is started without any problem.

Then, in the failure diagnosis when the battery acceptability is lowered, the valve opening time T of the purge valve 46 when detecting the second canister pressure Pcan2 is extended from the normal time, and the purpose thereof will be described below. It's a street.
When the intake amount Q decreases, the purge flow rate decreases, so that the differential pressure ΔPcan at the time of failure diagnosis decreases. Therefore, when the failure diagnosis is performed with the intake air amount Q of the engine 3 lowered to the lower limit of the monitor area, the differential pressure ΔPcan is reduced most, and even in this case, the intake manifold to the extent that the failure diagnosis is possible. A lower limit regarding the intake amount Q in the monitor region is set so that a negative pressure within 28 can be obtained. In the second method according to the present embodiment, the lower limit of the monitor region, which has almost no margin for the negative pressure in the intake manifold 28, is further switched in the direction of decreasing the intake air amount Q, so that a normal failure occurs due to the decrease in the negative pressure. There is a possibility that the diagnosis cannot be expected.

Therefore, in the present embodiment, as can be seen from the comparison with FIG. 9, the purge valve 46 when detecting the second canister pressure Pcan2 at the time of failure diagnosis when the battery acceptability to which the second method is applied is deteriorated. The valve opening time T is extended. Therefore, the decrease in the purge flow rate is compensated, and even in a situation where the differential pressure ΔPcan increases slowly, the second canister pressure Pcan2, which is about the same as in the normal state, is detected. Therefore, the fuel evaporative emission control device is normal or abnormal. Can be accurately determined.

In addition, if the valve opening time T of the purge valve 46 is not extended, it is necessary to individually set the failure determination value according to the difference in the second canister pressure Pcan2 between the normal time and the time when the battery acceptability is lowered. .. As a result, the condition setting of the failure diagnosis in advance becomes complicated, but by sharing the failure judgment value in this way, the trouble can be saved.
However, it is not always necessary to extend the valve opening time T of the purge valve 46, and instead, a small value may be applied as a failure determination value for determining the differential pressure Pcan as compared with the normal time. ..

FIG. 13 is a time chart showing an implementation status when the second method is applied to the failure diagnosis of the exhaust gas circulation device 24.
In this case, the control status of the operating point of the engine 3 during normal operation and when the battery acceptability is lowered is the same as the failure diagnosis of LAFS 22 described above except that the setting of the monitor area is different. Therefore, although not duplicated, even when the battery acceptability is lowered, the lower limit of the monitor area is switched in the direction of lowering the filling efficiency Ec, so that the monitor area deviates from the monitor area as shown by the broken line in the figure. The operating point of the engine 3 that has been used is kept within the monitor area, and the failure diagnosis is started without any problem.

As described above, if the second method according to the present embodiment is applied to any of the emission emission suppression devices, the traveling battery 15 can be protected by limiting the target charging power even when the battery acceptability of the traveling battery 15 deteriorates. , The operating point of the engine 3 can be kept within the monitor area to perform the failure diagnosis.
By the way, the above description of the first and second embodiments is a case where the battery acceptability has already deteriorated before the failure diagnosis is started, but the fuel evaporative emission suppression device 38 and the exhaust gas circulation device 24 have failed. It can also be applied when the battery acceptability deteriorates after the start of diagnosis. For example, if a failure diagnosis of the fuel evaporative emission control device 38 is started but the detection of the first canister pressure Pcan1 is not started yet, and a judgment of deterioration of battery acceptability is made, the engine is at that time. The switching of the operating points of 3 (first embodiment) or the expansion of the monitor area (second embodiment) may be executed. As a result, the operating point of the engine 3 is kept within the monitor area, so that the failure diagnosis can be performed without any problem as described above.

Although the description of the embodiment is completed above, the aspect of the present invention is not limited to this embodiment. For example, in the above embodiment, the traveling mode is embodied as a failure diagnosis device of the plug-in hybrid vehicle 1 capable of switching between the EV mode, the series mode, and the parallel mode, but the type of the vehicle 1 is not limited to this. It can be arbitrarily applied as long as it is a hybrid vehicle capable of executing a series mode in which a generator is driven by an engine and the generated power is charged to a traveling battery.

1 vehicle 3 engine 10 motor generator (generator)
15 Running battery 18 Hybrid controller (charge control means, battery acceptability determination means,
Charging power limiting means, failure diagnosis means, operating point correction means, monitor area expansion means)
22 LAFS (exhaust sensor, emission suppression means)
21 Catalyst device (emission emission suppression means)
28 Intake manifold (intake side)
38 Fuel evaporative emission control device (emission emission control means)
44 canister 46 purge valve

Claims (5)

A charge control means that operates an engine at a predetermined operating point to drive a generator and charges a battery with the electric power generated by the generator.
A battery acceptability determining means for determining whether or not the battery acceptability for which the charging power to the battery should be limited is deteriorated, and
When the battery acceptability determination means determines that the battery acceptability is low, the charging power limit that reduces the generated power by switching the operating point of the engine in the load reduction direction in order to limit the charging power to the battery. Means and
Emission emission control means to suppress emission emission to the atmosphere,
When the conditions for performing the failure diagnosis of the emission emission suppressing means are satisfied, the failure diagnosis is performed while keeping the operating point of the engine within the monitoring area defined by the load and the rotation speed. Means and
When the failure diagnosis of the emission emission suppressing means is performed by the failure diagnosis means, the monitor area deviates when the operating point of the engine is switched in the load reduction direction based on the determination of the battery acceptability determination means. in, and a monitor area enlargement means for keeping the operating point to expand the monitoring area in the load lowering direction to the enlarged monitored area,
The emission emission suppressing means is an exhaust sensor that detects the exhaust air-fuel ratio of the engine.
The failure diagnosis means forcibly vibrates the exhaust air-fuel ratio of the engine between the rich side and the lean side to diagnose deterioration based on the output change of the exhaust sensor, and the monitor by the monitor area expansion means. When the region is expanded, at least one of the forced vibration period or the amplitude is increased as compared with the normal time in order to compensate for the deterioration of the output followability of the exhaust sensor due to the decrease in the exhaust gas flow rate of the engine. A failure diagnosis device for hybrid vehicles. The emission emission suppressing means is an exhaust sensor that detects the exhaust air-fuel ratio of the engine.
The failure diagnosis device for a hybrid vehicle according to claim 1, wherein the failure diagnosis means diagnoses deterioration of the exhaust sensor. The emission emission suppressing means is a catalyst device that purifies the exhaust gas of the engine.
The failure diagnosis device for a hybrid vehicle according to claim 1, wherein the failure diagnosis means diagnoses deterioration of the catalyst device. The emission emission suppressing means is a fuel evaporation gas emission suppressing device that processes fuel evaporation gas generated in a fuel tank that stores fuel of the engine.
The failure diagnosis device for a hybrid vehicle according to claim 1, wherein the failure diagnosis means diagnoses a failure of the fuel evaporative emission suppression device. The emission emission suppressing means adsorbs the fuel evaporative gas generated in the fuel tank for storing the fuel of the engine to the canister, and uses the negative pressure on the intake side of the engine to adsorb the adsorbed fuel evaporative gas. It is a fuel evaporative emission suppression device that is transferred to the intake side and burned.
The failure diagnosis means causes a failure of the fuel exhaust gas emission suppression device based on a pressure change in the canister when the purge valve provided between the canister and the intake side of the engine is opened and closed. Whether to extend the opening time of the purge valve as compared with the normal time in order to make a diagnosis and compensate for the decrease in the purge flow rate due to the decrease in the exhaust gas flow rate of the engine when the monitor area is expanded by the monitor area expansion means. The failure diagnosis device for a hybrid vehicle according to claim 1, wherein at least one of applying a small value as a failure determination value for determining the pressure change is executed.

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