JP6774003B2 - Exhaust gas circulation failure diagnostic device for hybrid vehicles - Google Patents

Description

The present invention relates to an exhaust gas circulation failure diagnosis device for a hybrid vehicle, and more particularly to a failure diagnosis device for diagnosing a failure of an engine exhaust gas circulation device mounted on a vehicle.

As a device to reduce NOx contained in the exhaust gas of the engine mounted on the vehicle, the exhaust gas is circulated to the intake side as the exhaust gas circulation gas through the exhaust gas circulation passage connecting the exhaust side and the intake side of the engine. There is known an exhaust gas circulation device that lowers the combustion temperature inside and suppresses the generation of NOx. The circulation flow rate of the exhaust gas circulating gas to the intake side is optimized by controlling the opening degree of the exhaust gas circulation valve interposed in the exhaust gas circulation passage according to the operating region of the engine. However, the desired exhaust gas circulation circulation amount may not be achieved due to a failure of the exhaust gas circulation valve or clogging of the exhaust gas circulation passage, and if the exhaust gas circulation circulation flow rate is insufficient, the NOx emission amount will increase and the exhaust gas circulation circulation flow rate will increase. Excessive amount causes a decrease in drivability due to deterioration of combustion, or an increase in HC, CO, black smoke, etc. in the exhaust gas.

Therefore, for example, as described in Patent Document 1, the vehicle is provided with an exhaust gas circulation failure diagnosis device for diagnosing whether or not the exhaust gas circulation device is functioning normally. The vehicle described in Patent Document 1 is configured to be able to execute the series mode as one of the traveling modes. In the series mode, the motor generator is driven by the engine, and the generated power is used to drive the traveling motor or the traveling battery. It is used for charging.

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. 3, 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, 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 is accepted. When the engine is operating at the operating point marked with a circle outside the monitor area due to deterioration of the property, if the conditions for performing the failure diagnosis of the exhaust gas circulation device are satisfied, keep it at the operating point marked with a circle in the monitor area. The engine control 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 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. An object of the present invention is to provide an exhaust gas circulation failure diagnosis device for a hybrid vehicle capable of performing a failure diagnosis of an exhaust gas circulation device.

In order to achieve the above object, the exhaust gas circulation failure diagnosis device for a hybrid vehicle of the present invention operates an engine at a predetermined operating point to drive a generator, and charges a battery with the power generated by the generator. The charge control 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. At that time, the 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, the exhaust gas circulating means for circulating the exhaust gas of the engine, and the above. When the conditions for performing the failure diagnosis of the exhaust gas circulation means are satisfied, the exhaust gas circulation failure diagnosis means for carrying out the failure diagnosis of the exhaust gas circulation means while keeping the operating point of the engine within the monitor area defined by the load and the rotation speed. When the failure determination of the exhaust gas circulation failure means is performed by the exhaust gas circulation failure diagnosis means, the monitoring area is changed when the operating point of the engine is switched in the load reduction direction based on the determination of the battery acceptability determination means. When deviating, the control means for changing the operating area of the engine or expanding the monitoring area, and the first method for expanding the monitoring area in the load reduction direction and keeping the operating point within the expanded monitoring area. and a monitor area enlarging means, wherein at the time of expansion of the monitoring area of the first monitor area enlargement means, characterized in that to reduce the opening at the valve opening of the exhaust gas circulation valve in comparison to the normal time (according Item 1).

According to the exhaust gas circulation failure diagnosis device of the hybrid vehicle configured in this way, when the failure determination of the exhaust gas circulation failure means is performed by the exhaust gas circulation failure diagnosis means, the failure diagnosis of the exhaust gas circulation device is made by the determination of the battery acceptability determination means. Is done more often.
Further, when the failure determination of the exhaust gas circulation failure means is performed by the exhaust gas circulation failure diagnosis means, if 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 deviated. , The monitor area is expanded in the direction of load reduction. Therefore, it is possible to keep the operating point of the engine within the monitor area and perform a failure diagnosis of the exhaust gas circulation means while limiting the charging power for battery protection.
In addition, the engine at this time may be operated at the operating point in the load reduction direction to cause combustion deterioration, but combustion deterioration is caused by the opening opening of the exhaust gas circulation valve being reduced as compared with the normal time. Is suppressed.

As another aspect, the exhaust gas circulation failure diagnosis device reduces the opening degree of the exhaust gas circulation valve when the valve is opened as compared with the normal time when the monitoring area is expanded, and determines the pressure change on the intake side. It is preferable to apply a small value as the failure determination value (claim 2 ).
According to this aspect, when the opening degree of the exhaust gas circulation valve is reduced, the differential pressure from that when fully closed is reduced, but since a small value is applied as a failure determination value as compared with the normal time, the normal time The same judgment as is possible.

As another aspect, when the exhaust gas circulation failure diagnosis device expands the monitor area by the second monitor area expanding means for expanding the monitor area in the rotation increasing direction and the monitor area expanding means by the second monitor area expanding means, the engine It is preferable to have a second operating point correction means for switching the operating point of the above in the direction of increasing rotation (claim 3 ).
According to this aspect, when the failure determination of the exhaust gas circulation means is performed by the exhaust gas circulation exhaust gas circulation failure diagnosis means, when the operating point of the engine is switched in the load reduction direction based on the judgment of the battery acceptability determination means, the monitor area When the vehicle deviates from the above, the monitoring area is expanded in the direction of increasing rotation, and the operating point of the engine is switched in the direction of increasing rotation. Although the operating point of the engine deviates from the monitoring area in the direction of load reduction, the combustion state of the engine stabilizes due to the increase in the rotation speed. Therefore, while limiting the charging power to protect the battery, the exhaust gas circulation means It becomes possible to carry out failure diagnosis.

As another embodiment, the exhaust gas circulation failure diagnosis device expands the opening degree of the exhaust gas circulation valve at the time of opening the exhaust gas circulation valve when the operation point is switched by the second operation point correction means as compared with the normal time. It is preferable to have a valve expanding means (claim 4 ).
According to this aspect, due to the increase in engine rotation, the pressure change on the intake side of the engine due to the opening and closing of the exhaust gas circulation valve tends to decrease, which makes it easy to make an erroneous determination. Accurate determination becomes possible by expanding the opening degree of time.

The exhaust gas circulation failure diagnosis device provides a first operating point correction means for reducing the rotation speed of the engine while maintaining the load of the engine and keeping the operating point within the monitoring region while limiting the charging power. It is preferable to provide (claim 5 ).
According to the exhaust gas circulation failure diagnosis device of the hybrid vehicle configured in this way, when the failure determination of the exhaust gas circulation failure means is performed by the exhaust gas circulation failure diagnosis means, the operating point of the engine is determined based on the judgment of the battery acceptability determination means. If the engine deviates from the monitor area when the load is switched in the direction of reduction, the engine rotation speed is reduced while maintaining the engine load. Therefore, the operating point of the engine is monitored while limiting the charging power to protect the battery. It is possible to carry out failure diagnosis of the exhaust gas circulation means while keeping it within the area.

As another aspect, when the exhaust gas circulation failure diagnosis device can keep the operating point of the engine within the monitor area by the first operating point correcting means, the first operating point correcting means is made to execute the process. When the operating point cannot be kept in the monitor area by the first operating point correcting means, the corresponding switching means for causing the first monitoring area expanding means or the second monitoring area expanding means to execute the process. It is preferable to have (claim 6 ).

According to the exhaust gas circulation failure diagnosis device of the hybrid vehicle configured in this way, in the processing of the first operating point correction means, the failure diagnosis is performed while operating the engine within the original monitoring area where stable combustion can be expected. Therefore, the diagnostic accuracy is the highest. In the process of the first monitor area expanding means, the operating point of the engine can be more reliably maintained in the monitor area, but since the engine is operated at the operating point where the load is reduced, the diagnostic accuracy is inferior due to the deterioration of combustion. Similarly, the processing of the second monitor area expanding means also causes deterioration of engine combustion, and further increases engine rotation, which is disadvantageous in terms of noise and vibration.

According to the present invention, since the processing of the first operating point correction means is performed with priority, high diagnostic accuracy can be obtained, and when the processing of the first operating point correction means cannot be performed. Since the processing of the first monitor area expanding means or the second monitoring area expanding means is performed, it is possible to carry out the failure diagnosis even when the battery acceptability is lowered.

According to the exhaust gas circulation failure diagnosis device of the hybrid vehicle of the present invention, even when the battery acceptability of the traveling battery deteriorates, the failure diagnosis of the exhaust gas circulation device is performed while protecting the traveling battery by limiting the target charging power. Can be done.

It is an overall block diagram which shows the plug-in hybrid vehicle to which the exhaust gas circulation failure diagnosis apparatus of embodiment is applied. It is a block diagram which shows the exhaust gas circulation device provided in an engine. It is a map which shows the operating point of the engine in the monitor area at the time of failure diagnosis of 1st Embodiment. It is a time chart which shows the implementation state of the failure diagnosis of 2nd Embodiment. It is a time chart which shows the implementation state of the failure diagnosis of 3rd Embodiment.

Hereinafter, an embodiment in which the present invention is embodied in an exhaust gas circulation 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 exhaust gas circulation 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 and the operating region.

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 the current running battery 15 determined by the SOH (deterioration index: State of Health), SOC, temperature, etc. of the running battery 15. Is the maximum power that can be charged.

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, the engine 3 is provided with an exhaust gas circulation device 21 in order to reduce NOx contained in the exhaust gas, and the configuration thereof is shown in FIG.

The exhaust gas circulation device 21 includes an exhaust gas circulation passage 22 that connects the exhaust manifold 24 (exhaust side) and the intake manifold 25 (intake side) of the engine 3, and an exhaust gas circulation valve 23 that adjusts the opening degree of the exhaust gas circulation passage 22. Has been done. The opening degree of the exhaust gas circulation valve 23 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 side as the exhaust gas circulation gas through the exhaust gas circulation passage 22 according to the opening degree of the exhaust gas circulation valve 23. As a result, the combustion temperature in the cylinder is lowered and the generation of NOx is suppressed.

If the desired amount of exhaust gas circulation and recirculation cannot be achieved due to a failure of the exhaust gas circulation valve 23, clogging of the exhaust gas circulation passage 22, or the like, various problems occur in terms of emission and drivability. Therefore, the vehicle 1 has exhaust gas. An exhaust gas circulation failure diagnosis device (exhaust gas circulation failure diagnosis means) for diagnosing a failure of the circulation device 21 is provided. In the present embodiment, the pressure sensor 26 and the hybrid controller 18 provided in the intake manifold 25 function as the exhaust gas circulation failure diagnosis device, and as will be described later, the exhaust gas circulation valve 23 in which the hybrid controller 18 is detected by the pressure sensor 26. The normality / abnormality of the exhaust gas circulation device 21 is determined by comparing the differential pressure ΔP between when fully closed (0%) and when the predetermined amount is opened (20%) with the failure determination value.

The failure diagnosis of the exhaust gas circulation device 21 is performed 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 filling efficiency Ec (load) is the traveling battery 15. The value at the normal time based on the target charging power to is switched to the value on the lower load side suitable for failure diagnosis. Specifically, a monitor area for failure diagnosis (for example, 1250 to 1750 rpm, 15 to 25%) is set in advance, and the center of the monitor area is set as a target operating point of the engine 3 (for example, 1500 rpm, 20%). There is.

FIG. 3 is a map showing the operating points of the engine 3 in the monitor area at the time of failure diagnosis. For example, the monitor area is set as shown by the hatch frame in the figure, and the operating points indicated by ● in the monitor area. Failure diagnosis is carried out while operating the engine 3. As shown in the figure, as the rotation speed Ne of the engine 3 increases or the filling efficiency Ec increases, misfire is suppressed and the combustion state of the engine 3 becomes better, but the exhaust gas circulation The differential pressure ΔP accompanying the opening and closing of the valve 23 is reduced, increasing the possibility of erroneously determining the failure diagnosis.

In this way, the failure diagnosis is carried out based on the monitor area, but as described in [Problems to be solved by the invention], when the battery acceptability is lowered, the traveling battery 15 is used rather than the failure diagnosis of the exhaust gas circulation. As a result of giving priority to protection, the operating point of the engine 3 deviates from the monitor area to the low load side as shown by a circle in FIG. 3, and there is a problem that the failure diagnosis of the exhaust gas circulation device 21 cannot be completed.

In view of such a defect, the present inventor has found the following two measures in order to complete the failure diagnosis of the exhaust gas circulation device 21 while limiting the target charging power for the protection of the traveling battery 15.
One is a method of optimizing the operating point of the engine 3 in the monitor area to enable failure diagnosis, and the other is a method of expanding the monitor area. Hereinafter, the first-stage method will be described as the first embodiment, and the second-stage method will be described as the second and third embodiments.
[First 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. 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. 3, 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 a monitor area in the direction of decrease in load (filling efficiency Ec), whereas the rotation speed. It can be seen that there is some room in the downward direction of 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 exhaust gas circulation device 21 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 to the load reduction direction and the monitor area is deviated, the rotation speed Ne is reduced while maintaining the current filling efficiency Ec of the engine 3. Then, the operating point is switched to the □ mark in the figure (first operating point correction means).

Further, when the engine 3 is operated at the operation 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 decrease in the battery acceptability of the traveling battery 15, the exhaust gas circulation device 21 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 engine 3 is operated on the characteristic line of 20 kW while increasing the filling efficiency Ec of the engine 3 and decreasing the rotation speed Ne. Move the operating point of to the □ mark.

In either case, the target power generation amount of the motor generator 10 and the target charging power of the traveling battery 15 are limited, and the operating point of the engine 3 is kept within the monitor area. Therefore, according to the present embodiment, even when the battery acceptability of the traveling battery 15 is lowered, the exhaust gas circulation is performed while keeping the operating point of the engine 3 within the monitoring region while protecting the traveling battery 15 by limiting the target charging power. Failure diagnosis of the device 21 can be performed.
[Second Embodiment]
As described above, the monitor area is defined by the rotation speed Ne of the engine 3 and the filling efficiency Ec, and when the operating point of the engine 3 falls below the lower limit of the filling efficiency Ec due to the limitation of the target power generation amount of the motor generator 10. The failure diagnosis of the exhaust gas circulation device 21 cannot be performed. Therefore, only when the battery acceptability of the traveling battery 15 is lowered, the operating point of the engine 3 is switched by expanding the monitor area in the load lowering direction, and more specifically, lowering the lower limit of the filling efficiency Ec of the monitor area. In this embodiment, a method of keeping the battery within the monitor area is adopted.

FIG. 4 is a time chart showing the implementation status of the failure diagnosis of the present embodiment. As a premise of the explanation, the monitoring area for failure diagnosis is preset to 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 the targets at the time of failure diagnosis. It is set as an operating point, and when the battery acceptability is further lowered, the operating point of the engine 3 is assumed to be lowered to a filling efficiency Ec10% (marked with a circle in FIG. 3) due to the power generation limitation of the motor generator 10.

First, a failure diagnosis in a normal state in which the battery acceptability of the traveling battery 15 is not deteriorated will be described. When the conditions for performing the failure diagnosis of the exhaust gas circulation device 21 are not satisfied, as described above, the engine 3 is operated at the operating point where the target power generation amount of the motor generator 10 can be achieved with the minimum fuel consumption, and the exhaust gas circulation valve 23 is operated. The opening degree is controlled according to the operating region of the engine 3.
When the failure diagnosis execution condition is satisfied, a request for switching the operating point of the engine 3 to the monitor area is made, and the operating point of the engine 3 is switched to the target operating point in the monitor area in response to the request. Since the motor generator 10 is not restricted in power generation, the engine 3 is operated at the target operating point without any problem and continues to be kept within the monitor area. At this point, the exhaust gas circulation valve 23 is once fully closed (0%), the detection value of the intake manifold pressure by the pressure sensor 26 is stored as the first pressure P1, and then the exhaust gas circulation valve 23 is opened by a predetermined amount (20). %), And the detected value of the intake manifold pressure is stored as the second pressure P2. When the differential pressure ΔP of the first and second pressures P1 and P2 is equal to or higher than the preset failure determination value, the exhaust gas circulation device 21 makes a normal determination, and when it is less than the failure determination value, an abnormality determination is made.

After the normal / abnormal determination, the failure diagnosis implementation condition is not satisfied, the engine 3 is operated again at the operating point based on the target power generation amount of the motor generator 10, and the exhaust gas circulation valve 23 is operated according to the operating region of the engine 3. The opening is controlled.
On the other hand, a case where the battery acceptability of the traveling battery 15 is lowered will be described. At this time, the operating point of the engine 3 is lowered to 10%, which is lower than the lower limit filling efficiency Ec15% of the monitor area due to the power generation limitation of the motor generator 10, so that it is normally considered to deviate from the monitor area. It is done and 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 from the filling efficiency Ec 15% to 10% and is expanded in the load reduction direction as shown by the virtual line in FIG. First monitor area expansion means). Therefore, as shown by the broken line in FIG. 4, even at the operating point of the engine 3 having a filling efficiency of Ec10%, the operating point is considered to be kept within the monitor area, and the failure diagnosis is started without any problem. ..

Then, in the failure diagnosis when the battery acceptability is lowered, the opening degree and the failure determination value of the exhaust gas circulation valve 23 different from the normal time are applied, and the purpose thereof is as described below.
As described in [Background Technology], the monitor area is set to the lower load side compared to the normal operation in the series mode as a result of considering the diagnostic accuracy, etc., and the lower limit of the filling efficiency Ec15% is set. Even if the exhaust gas circulation valve 23 is fully opened, the combustion state of the engine 3 is deteriorated by the exhaust gas circulation gas, and the value is set near the limit that does not lead to misfire. In this embodiment, the lower limit of the monitor region, which has almost no margin for combustion stability, is further lowered to a filling efficiency of Ec of 10%, so that a normal failure diagnosis may not be expected due to deterioration of combustion of the engine 3.

Therefore, in the present embodiment, at the time of failure diagnosis when the battery acceptability is lowered, the opening degree of the exhaust gas circulation valve 23 is smaller than the fully opened opening applied at normal times, for example, 10% shown by a broken line in FIG. It only suppresses the deterioration of combustion. Further, when the opening degree of the exhaust gas circulation valve 23 becomes smaller, the differential pressure ΔP from the fully closed state is reduced as shown by the broken line in FIG. 4, so that the failure determination value is also smaller than the normal time. Is applied.

As described above, according to the present embodiment, when the execution condition of the failure diagnosis is satisfied in a state where the operating point of the engine 3 is lowered to the filling efficiency Ec10% due to the deterioration of the battery acceptability, the lower limit of the monitor area is set. The filling efficiency Ec is reduced to 10% and the load is decreasing. Therefore, the operating point of the engine 3 is kept within the monitor area, and the failure diagnosis can be performed without any problem.
Since the opening degree of the exhaust gas circulation valve 23 at the time of failure diagnosis is kept smaller than the opening degree at the time of normal operation, it is possible to suppress the deterioration of combustion of the engine 3 due to the recirculation of the exhaust gas circulating gas. Further, since an appropriate failure determination value corresponding to the reduction of the exhaust gas circulation valve opening degree is applied, the normality / abnormality of the exhaust gas circulation device 21 can be accurately determined as in the normal case. As a result, according to the present embodiment, even when the battery acceptability of the traveling battery 15 is lowered, the traveling battery 15 is protected by the limitation of the target charging power, and the operating point of the engine 3 is maintained within the monitoring region to circulate the exhaust gas. Failure diagnosis of the device 21 can be performed.

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.
By the way, the above description is the case where the battery acceptability has already deteriorated before the start of the failure diagnosis, but it can also be applied to the case where the battery acceptability has deteriorated after the start of the failure diagnosis. For example, if the failure diagnosis is started but the intake manifold pressure detection is not started yet, and the battery acceptability is judged to be low, the operating point of the engine 3 is lowered to the filling efficiency Ec10% at that time. At the same time, the lower limit of the monitor area may be switched to the filling efficiency Ec10%. 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.

If the battery acceptability is determined to decrease after the intake manifold pressure is detected, the operating point of the engine 3 is lowered to a filling efficiency of Ec10%, and the lower limit of the monitor area is switched to a filling efficiency of Ec10%. Then, the intake manifold pressure may be detected from the beginning.
[Third Embodiment]
The monitor area is expanded in the present embodiment as in the second embodiment, but the purpose is to include the operating point of the filling efficiency Ec (for example, 10%) below the lower limit of the normal monitor area in the monitor area. However, by stabilizing the combustion of the engine 3, it is possible to carry out a failure diagnosis of the exhaust gas circulation device 21 even if the operating point remains outside the monitor region.

FIG. 5 is a time chart showing the implementation status of the failure diagnosis of the present embodiment.
In the present embodiment, as a countermeasure against the deterioration of combustion of the engine 3, the target operating point of the engine 3 is switched in the direction of increasing rotation, for example, from 1500 rpm to 2000 rpm as shown by the broken line in FIG. 5 (second operating point correction means). The upper limit of the rotation speed Ne of the monitor area is also expanded from 1750 rpm to 2000 rpm (second monitor area expansion means). As a result, the engine 3 is operated at a target operating point of 2000 rpm and 10%, and as can be seen from the map of FIG. 3, the combustion state of the engine 3 is stabilized by increasing the rotation speed Ne. The operating point is in the monitor region expanded in the direction of increasing rotation with respect to the rotation speed Ne, and the filling efficiency Ec is still below the lower limit of 15% of the monitor region. However, it is considered that the environment in which the failure diagnosis can be performed is prepared by the stabilization of combustion, and in the present embodiment, the failure diagnosis of the exhaust gas circulation device 21 is started as it is.

Since the failure diagnosis is originally started based on the comparison between the monitor area and the operating point of the engine 3, the lower limit of the monitoring area is expanded in the load reduction direction as in the second embodiment, and the operating point is monitored. Failure diagnosis may be started after confirming that the area is kept within the area.
Then, when the rotation speed Ne of the engine 3 increases in this way, as shown by the broken line in FIG. 5, the differential pressure ΔP tends to decrease as compared with the normal time even if the exhaust gas circulation opening degree is the same, resulting in an erroneous determination. It becomes easier to do. Therefore, normally, the opening degree of the exhaust gas circulation valve 23 is limited to a small opening degree, for example, 20% shown by the solid line in FIG. 5, and when the battery acceptability is lowered, the opening degree of the exhaust gas circulation valve 23 is set to 40 as shown by the broken line. The amount has been increased to%.

As described above, according to the present embodiment, the combustion of the engine 3 is stabilized by expanding the monitoring area at the time of failure diagnosis in the direction of increasing rotation and then switching the target operating point of the engine 3 in the direction of increasing rotation. After that, the failure diagnosis of the exhaust gas circulation device 21 is carried out. Therefore, although the filling efficiency Ec deviates from the monitoring area, since the engine 3 is operated in a high rotation range where misfire is unlikely to occur, combustion deterioration due to misfire even if exhaust gas circulating gas is introduced by failure diagnosis. Can be suppressed.

Further, since the opening degree of the exhaust gas circulation valve 23 is expanded as compared with the normal time in order to prevent the differential pressure ΔP from being reduced due to the increase in the rotation of the engine 3, the exhaust gas is exhaust gas based on the same failure determination value as in the normal time. The normality / abnormality of the circulation device 21 can be accurately determined. As a result, according to the present embodiment, even when the battery acceptability of the traveling battery 15 is lowered, the failure diagnosis of the exhaust gas circulation device 21 can be performed while protecting the traveling battery 15 by limiting the target charging power.

In the present embodiment, the exhaust gas circulation opening is changed in order to eliminate the difference in the differential pressure ΔP between the normal time and the time when the battery acceptability is lowered, but instead, the exhaust gas circulation opening is changed when the battery acceptability is lowered as compared with the normal time. A small value may be applied as the failure determination value.
Further, 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. Further, as described in the second embodiment, the control of the present embodiment may be out of order. It may be applied when the battery acceptability deteriorates after the start of the diagnosis.

By the way, as described above, in each embodiment, when the failure diagnosis of the exhaust gas circulation device 21 is performed, if the operating point of the engine 3 is switched in the load reduction direction based on the determination of the decrease in battery acceptability, does the monitor region deviate? Whether or not it is determined (area deviation determination means). Then, when it is determined that the monitor region deviates from the monitor region, the operating point of the engine 3 is switched and kept within the monitor region in the first embodiment (the first operating point correction means, in the second embodiment, the monitor region is loaded. It expands in the downward direction and is kept in the monitor area without switching the operating point of the engine 3 (first monitor area expansion means), and in the third embodiment, the monitor area is expanded in the rotation increasing direction and the engine 3 The operating point is switched in the direction of increasing rotation (second monitor area expanding means).

Since each of these methods has advantages and disadvantages, it is conceivable to use them in combination with each other.
That is, the method of the first embodiment has the highest diagnostic accuracy because the failure diagnosis is performed while operating the engine 3 within the original monitor region where stable combustion can be expected. On the other hand, depending on the relationship between the characteristic line in the monitor area and the operating point of the engine 3 before switching, the operating point may not be kept in the monitor area even if the rotation speed is reduced.

The method of the second embodiment is more reliable than the first embodiment in keeping the operating point within the monitor area. On the other hand, if the operating point of the engine 3 is significantly lowered with respect to the filling efficiency Ec, a failure diagnosis is performed at that operating point, so even if measures are taken to reduce the opening degree of the exhaust gas circulation valve 23. Deterioration of combustion is unavoidable, and due to this factor, the diagnostic accuracy is inferior to that of the first embodiment.

Although the method of the third embodiment aims at combustion stability by increasing the rotation of the engine 3, combustion deterioration is avoided because the failure diagnosis is performed at the operating point where the filling efficiency Ec is low as in the second embodiment. I can't. Further, since the engine rotation is increased and noise and vibration are increased every time a failure diagnosis is made, good NVH performance cannot be obtained, which may cause a sense of discomfort to the driver.
Therefore, it can be determined that the order in which the implementation is desirable is the order of the first, second, and third embodiments. Therefore, for example, when the operating point of the engine 3 can be kept within the monitor area by the method of the first embodiment, the failure diagnosis is performed by the method of the first embodiment, and the operating point of the engine 3 is carried out by the method of the first embodiment. If the above is not kept in the monitor area, the failure diagnosis may be performed by the method of the second embodiment or the method of the third embodiment (corresponding switching means).

If each method is appropriately switched in this way, the method of the first embodiment is first implemented with priority, so that high diagnostic accuracy can be obtained, and the method of the first embodiment cannot be implemented. However, since the method of the second embodiment or the third embodiment can be implemented, it is possible to carry out the failure diagnosis even when the battery acceptability is lowered.
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 driving mode is embodied in the exhaust gas circulation failure diagnosis device of the plug-in hybrid vehicle 1 that can switch between the EV mode, the series mode, and the parallel mode, but the type of the vehicle 1 is not limited to this. Absent. 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 (control means, exhaust gas circulation valve expansion means, exhaust gas circulation means, charge control means, battery acceptability determination means, charging power limiting means, exhaust gas circulation failure diagnosis means, first and second operating point correction means , 1st and 2nd monitor area expansion means, area deviation determination means, corresponding switching means)
21 Exhaust gas circulation device (exhaust gas circulation means)
22 Exhaust gas circulation passage 23 Exhaust gas circulation valve 24 Exhaust manifold (exhaust side)
25 Intake manifold (intake side)
26 Pressure sensor (exhaust gas circulation failure diagnosis means)

Claims (6)

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
Exhaust gas circulation means for circulating the exhaust gas of the engine and
When the conditions for performing the failure diagnosis of the exhaust gas circulation means are satisfied, the exhaust gas circulation failure diagnosis means for carrying out the failure diagnosis of the exhaust gas circulation means within the monitoring region defined by the load and the rotation speed of the operating point of the engine. ,
When the failure determination of the exhaust gas circulation failure means is performed by the exhaust gas circulation failure diagnosis means, if 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 region is deviated. In some cases, a control means for changing the operating area of the engine or expanding the monitoring area, and
A first monitor area expanding means for expanding the monitor area in the load reduction direction and keeping the operating point within the expanded monitor area is provided.
Wherein at the time of expansion of the monitoring area of the first monitor area enlargement means it is usually exhaust gas circulation failure diagnosis apparatus for a hybrid vehicle, characterized in that to reduce the opening at the valve opening of the exhaust gas circulation valve in comparison with the time. The exhaust gas circulation failure diagnosis device reduces the opening degree of the exhaust gas circulation valve when the valve is opened when the monitoring area is expanded, and is small as a failure determination value for determining a pressure change on the intake side. The exhaust gas circulation failure diagnosis device for a hybrid vehicle according to claim 1, wherein a value is applied. The exhaust gas circulation failure diagnosis device includes a second monitor area expanding means for expanding the monitor area in the direction of increasing rotation.
The first or second claim, wherein the second operating point correction means for switching the operating point of the engine in the rotation increasing direction when the monitoring area is expanded by the second monitoring area expanding means is provided. Exhaust gas circulation failure diagnosis device for hybrid vehicles. The exhaust gas circulation failure diagnosis device includes an exhaust gas circulation valve expanding means for expanding the opening degree of the exhaust gas circulation valve when the valve is opened as compared with a normal time when the operating point is switched by the second operating point correcting means. The exhaust gas circulation failure diagnosis device for a hybrid vehicle according to claim 3, wherein the exhaust gas circulation failure diagnosis device is characterized. The exhaust gas circulation failure diagnosis device provides a first operating point correction means that reduces the rotational speed of the engine while maintaining the load of the engine and keeps the operating point within the monitoring region while limiting the charging power. The exhaust gas circulation failure diagnosis device for a hybrid vehicle according to any one of claims 1 to 4, wherein the device is provided. When the operating point of the engine can be kept within the monitoring region by the first operating point correcting means, the exhaust gas circulation failure diagnosis device causes the first operating point correcting means to execute the process, and the first operating point correcting means. When the operating point cannot be kept within the monitor area by the operating point correcting means, the first monitoring area expanding means or the second monitoring area expanding means has a corresponding switching means for executing the process. The exhaust gas circulation failure diagnosis device for a hybrid vehicle according to any one of claims 3 to 5.

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