Hybrid vehicle control device

Abstract

To suppress occurrence of failure in which fuel economy and an exhaust gas deteriorate according to the resumption of a catalyst deterioration diagnosis after re-start of an internal combustion engine as the internal combustion engine stops in the middle of the catalyst deterioration diagnosis, in a control device for a hybrid vehicle which is used for a hybrid vehicle on which an internal combustion engine and an electric motor are mounted as a power source, estimates oxygen storage capacity of a catalyst for exhaust gas purification mounted on an exhaust passage of the internal combustion engine, and performs catalyst deterioration diagnosis control for diagnosing whether or not the catalyst has deteriorated by determining whether or not the oxygen storage capacity is equal to or greater than a threshold value.SOLUTION: A period is set in which estimation of oxygen storage capacity of a catalyst is not performed immediately after start of catalyst deterioration diagnosis control, execution of the catalyst deterioration diagnosis control is permitted in the case where an operation state of an internal combustion engine is a predetermined state, and execution of the catalyst deterioration diagnosis control is not permitted in the case where the operation state of the internal combustion engine is other than the predetermined state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device that performs self-diagnosis regarding deterioration of a catalyst of an internal combustion engine mounted on a hybrid vehicle.

Background Art

[0002] Conventionally, it has been known to perform catalyst deterioration diagnosis for determining deterioration of a catalyst by performing active control in which the air-fuel ratio is forcibly switched between the rich side and the lean side with respect to the stoichiometric air-fuel ratio. This catalyst deterioration diagnosis monitors the outputs of air-fuel ratio sensors arranged upstream and downstream of the catalyst, respectively, and estimates the oxygen storage amount of the catalyst based on the time from when the air-fuel ratio on the upstream side changes from the rich side to the lean side or vice versa until the air-fuel ratio on the downstream side changes similarly (see, for example, Patent Document 1).

[0003] Here, immediately after the start of the active control, since a part of the exhaust gas generated before the start of the active control also reaches the catalyst and the oxygen storage and desorption ability of the catalyst cannot be accurately measured, a period is provided during which the estimation of the oxygen storage amount of the catalyst through monitoring the output of the air-fuel ratio sensor is not performed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, in a hybrid vehicle, the firing of the internal combustion engine is repeatedly stopped and started depending on the driving conditions. At that time, the firing of the internal combustion engine may stop during the catalyst deterioration diagnosis, and the catalyst deterioration diagnosis may be restarted after the internal combustion engine is restarted.

[0006] Then, only active control is performed immediately after the start of catalyst deterioration diagnosis, and a period during which the output of the air-fuel ratio sensor is not monitored is repeated. Also, since the period during which active control is performed becomes longer, there is a possibility of deterioration of fuel consumption and exhaust gas.

[0007] An object of the present invention is to suppress the occurrence of the above-described problems associated with the restart of catalyst deterioration diagnosis after the internal combustion engine stops during catalyst deterioration diagnosis and the restart of the internal combustion engine in a hybrid vehicle.

Means for Solving the Problems

[0008] In order to solve the above-described problems, the present invention is used in a hybrid vehicle equipped with an internal combustion engine and an electric motor as power sources, estimates the oxygen storage capacity of a catalyst for purifying exhaust gas mounted in the exhaust passage of the internal combustion engine, and determines whether the oxygen storage capacity is equal to or greater than a threshold value. A control device for a hybrid vehicle that performs catalyst deterioration diagnosis control for diagnosing whether the catalyst is deteriorated, and sets a period during which the oxygen storage amount of the catalyst is not estimated immediately after the start of the catalyst deterioration diagnosis control. When the operating state of the internal combustion engine is a predetermined in a state case, execution of catalyst deterioration diagnosis control is permitted to do so, and the predetermined state is a state in which the intake air amount to the cylinder of the internal combustion engine is equal to or more than a predetermined value and the firing operation of the internal combustion engine can be continued for a predetermined time or more, When the operating state of the internal combustion engine is the other than the predetermined state, a control device for a hybrid vehicle that does not permit execution of catalyst deterioration diagnosis control is configured.

[0009] More specifically, the predetermined state is when starting the vehicle, when acceleration is required, when the operation of the heating device is required, when the operation of the defroster is required, or when the operation of the air conditioner is required, including at least one of these cases .

Advantages of the Invention

[0010] According to the present invention, in a hybrid vehicle, during catalyst deterioration diagnosis, the firing of the internal combustion engine stops, and after the restart of the internal combustion engine, catalyst deterioration diagnosis is restarted, so that only active control is performed and a period during which the air-fuel ratio is not monitored is repeated. In addition, it is possible to suppress deterioration of fuel consumption and exhaust gas associated with an increase in the period during which active control is performed.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of the main systems of the hybrid vehicle according to this embodiment. This hybrid vehicle includes an internal combustion engine 1, a power generation motor generator 2 driven by the internal combustion engine 1 to generate electricity, a power storage device 3 that stores the electricity generated by the power generation motor generator 2, and a traveling motor generator 4 that receives power supply from the power generation motor generator 2 and / or the power storage device 3 and drives the drive wheels 62 of the vehicle.

[0013] The hybrid vehicle of this embodiment is a series hybrid electric vehicle that uses the internal combustion engine 1 only for power generation, and the drive wheels 62 of the vehicle are exclusively supplied with driving force for traveling from the traveling motor generator 4. The internal combustion engine 1 and the drive wheels 62 are mechanically disconnected, and originally no rotational driving force is transmitted between the two. That is, the internal combustion engine 1 can rotate completely independently of the traveling motor generator 4 and the drive wheels 62, and can also stop completely independently. Therefore, even when the vehicle can travel by the driver stepping on the accelerator pedal during the operation of the vehicle with the ignition switch (power switch or ignition key) turned ON, the internal combustion engine 1 may not be operated (fired) with fuel combustion under the condition that the power storage device 3 stores sufficient charge and the brake booster 15 stores sufficient negative pressure.

[0014] The crankshaft, which is the rotating shaft of the internal combustion engine 1, is mechanically connected to the rotating shaft of the power generation motor generator 2 via a gear mechanism or by directly connecting the shafts. Then, by inputting the rotational driving force output by the internal combustion engine 1 to the power generation motor generator 2, the power generation motor generator 2 generates electricity. The generated electricity is charged to the power storage device 3 and / or supplied to the driving motor generator 4. Further, the power generation motor generator 2 also functions as an electric motor for motoring that generates a rotational driving force by itself and rotates the crankshaft of the internal combustion engine 1. For example, the power generation motor generator 2 performs motoring (cranking) as a preparation for starting the stopped internal combustion engine 1.

[0015] The driving motor generator 4 generates a driving force for the vehicle to travel, and inputs the driving force to the drive wheels 62 via the speed reducer 61. Further, the driving motor generator 4 generates electricity by rotating while being rotated by the drive wheels 62, and recovers the kinetic energy of the vehicle as electric energy. The electricity generated by this regenerative braking is charged to the power storage device 3.

[0016] However, if the power storage device 3 is already fully charged and further charging is difficult, the driving motor generator 4 deliberately supplies the electricity generated by regenerative power generation to the power generation motor generator 2, and operates the power generation motor generator 2 as an electric motor to rotationally drive the internal combustion engine 1. Thereby, while maintaining the braking performance of the vehicle, the surplus power is exhausted. Also, at this time, since the rotation of the internal combustion engine 1 is maintained, it is possible to execute fuel cut that temporarily stops the fuel supply to the cylinders of the internal combustion engine 1.

[0017] The generator inverter 21 converts the AC power generated by the power generation motor generator 2 into DC power. Then, the DC power is input to the power storage device 3 or the drive motor inverter 41. Further, when operating the power generation motor generator 2 as an electric motor, the generator inverter 21 converts the DC power supplied from the power storage device 3 and / or the drive motor inverter 41 into AC power and then inputs it to the power generation motor generator 2.

[0018] The drive motor inverter 41 converts the DC power supplied from the power storage device 3 and / or the generator inverter 21 into AC power and inputs it to the driving motor generator 4. Further, when performing regenerative braking of the vehicle, the drive motor inverter 41 converts the AC power generated by the driving motor generator 4 into DC power and inputs it to the power storage device 3 or the generator inverter 21. The generator inverter 21 and the drive motor inverter 41 form part of a PCU (Power Control Unit) 02.

[0019] The power storage device 3 is a battery and / or a capacitor or the like. The battery is a high-voltage secondary battery with a large energy density, such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery, for example. The power storage device 3 charges and stores the electric power generated by each of the power generation motor generator 2 and the driving motor generator 4. Further, the power storage device 3 discharges the electric power for operating each of the power generation motor generator 2 and the driving motor generator 4 as an electric motor, and supplies the necessary electric power to those motor generators 2 and 4.

[0020] The ECU (Electronic Control Unit) 0, which is a control device that controls the internal combustion engine 1, the power generation motor generator 2, the power storage device 3, the inverters 21 and 41, and the driving motor generator 4, is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. The ECU 0 is composed of a plurality of ECUs, that is, an EFI (Electronic Fuel Injection) ECU 01 that controls the internal combustion engine 1, an MG (Motor Generator) ECU 02 that controls the motor generators 2 and 4 and the inverters 21 and 41, a BMS (Battery Management System) ECU 03 that controls the power storage device 3, and a higher-level controller HV (Hybrid Vehicle) ECU 00 that oversees their control, which are connected to be mutually communicable via an electrical communication line such as a CAN (Controller Area Network).

[0021] For the ECU0, signals output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle or a wheel speed sensor that detects the rotational speed of the wheels, a crank angle signal output from a crank angle sensor that detects the rotational angle and engine speed of the crankshaft of the internal combustion engine 1, an accelerator opening signal output from a sensor that detects the depression amount of the accelerator pedal by the driver as the accelerator opening (i.e., the driving force demanded by the driver for the vehicle (the driving motor generator 4)), an intake air temperature and intake air pressure signal output from an intake air temperature and intake air pressure sensor that detects the intake air temperature and intake air pressure in the intake passage (particularly, the surge tank or intake manifold) connected to the cylinders of the internal combustion engine 1, a coolant water temperature signal output from a coolant water temperature sensor that detects the temperature of the coolant water of the internal combustion engine 1, an atmospheric pressure signal output from an atmospheric pressure sensor that detects the atmospheric pressure, a battery SOC (State Of Charge) signal output from a sensor (particularly, a battery current and / or battery voltage sensor) that detects the amount of charge stored in the power storage device 3, a negative pressure signal output from a negative pressure sensor that detects the negative pressure stored in the constant pressure chamber of the brake booster, etc. are input.

[0022] Then, the ECU0 increases or decreases the control of the rotational driving force output by the driving motor generator 4, the rotational driving force output by the internal combustion engine 1, and the magnitude of the electric power generated by the power generation motor generator 2 according to the depression amount of the accelerator pedal operated by the driver, the current vehicle speed of the vehicle, the amount of charge stored in the power storage device 3, the generated electric power of the power generation motor generator 2, etc. sensed through various sensors.

[0023] The EFI ECU01, which is part of the ECU0, acquires various information necessary for the operation control of the internal combustion engine 1 via the input interface, obtains the engine speed, and estimates the amount of air inhaled into the cylinder. Then, it determines the operating parameters of the internal combustion engine 1, such as the required fuel injection amount (necessary to implement the target air-fuel ratio), fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, ignition timing (including the number of ignitions for one combustion), required EGR rate (or EGR gas amount), etc. The EFI ECU01 outputs various control signals corresponding to the operating parameters to the igniter of the spark plug, injector, throttle valve, EGR valve, etc. via the output interface.

[0024] The ECU0 performs feedback control on the air-fuel ratio of the air-fuel mixture filled in the cylinder, and thus the air-fuel ratio of the exhaust gas discharged from the cylinder and led to the catalyst. First, the ECU0 calculates the amount of fresh air filled in the cylinder from the intake pressure and intake temperature, engine speed, required EGR rate, etc., and determines the basic injection amount TP corresponding thereto.

[0025] Next, this basic injection amount TP is corrected by the feedback correction coefficient FAF determined according to the air-fuel ratio on the upstream side and / or downstream side of the catalyst. Generally, the feedback correction coefficient FAF is adjusted according to the deviation between the air-fuel ratio of the gas measured via the air-fuel ratio sensor and the target air-fuel ratio (near the stoichiometric air-fuel ratio during normal operation), increasing when the measured air-fuel ratio is lean with respect to the target air-fuel ratio and decreasing when the measured air-fuel ratio is rich with respect to the target air-fuel ratio.

[0026] And then, considering various correction coefficients K determined according to the situation of the internal combustion engine 1 and the ineffective injection time TAUV of the injector, the final fuel injection time (energization time for the injector) T is calculated. The fuel injection time T is T = TP × FAF × K + TAUV Thus, only the signal j is input to the injector for the fuel injection time T, and the injector is opened to inject fuel.

[0027] Feedback control with reference to the air-fuel ratio signal on the upstream side and / or downstream side of the catalyst is performed, for example, in an internal combustion engine 1 when the coolant water temperature of the engine is equal to or higher than a predetermined temperature, not during fuel cut, not during power increase, and a predetermined time has elapsed since the start of the internal combustion engine 1 and all conditions such as the air-fuel ratio sensor being warmed up and active and the intake pressure being normal are satisfied.

[0028] The ECU0 of the present embodiment performs catalyst deterioration diagnosis control (diagnosis) for estimating the maximum oxygen storage capacity of the catalyst, comparing the estimated maximum oxygen storage capacity value with a deterioration determination threshold value, and determining whether the catalyst is normal or abnormal.

[0029] The oxygen storage capacity of the catalyst can be estimated by adopting any known method, and here a typical example thereof is shown. From a state where an air-fuel ratio lean air-fuel mixture is supplied to the cylinder of the internal combustion engine and the catalyst has stored oxygen up to its maximum capacity, active control is executed to intentionally make the air-fuel ratio of the air-fuel mixture supplied to the cylinder rich. Then, the output signal (output current or output voltage) of the air-fuel ratio sensor upstream of the catalyst immediately indicates a rich air-fuel ratio. On the other hand, the output signal of the air-fuel ratio sensor downstream of the catalyst indicates a rich air-fuel ratio with a delay from the output signal of the air-fuel ratio sensor upstream. This is because the oxygen stored in the catalyst is released and the oxygen deficiency is compensated during the period from when the output signal of the air-fuel ratio sensor upstream of the catalyst indicates a rich air-fuel ratio (or from when the air-fuel mixture is made rich) until the output signal of the air-fuel ratio sensor downstream of the catalyst indicates a rich air-fuel ratio. 1 Let the time elapsed from when the output signal of the air-fuel ratio sensor upstream of the catalyst indicates a rich air-fuel ratio until the output signal of the air-fuel ratio sensor downstream of the catalyst indicates a rich air-fuel ratio be T

[0030] Let the total weight of the fuel supplied during this T be G R and let the difference between the theoretical air-fuel ratio and the rich air-fuel ratio be ΔA / F R F R R R R R R (α·ΔA / F R·G F ) becomes α. α is the weight ratio of oxygen in the air (≈0.23).

[0031] The above formula represents the amount of oxygen released by the catalyst up to the time of T R . The total weight G of the supplied fuel F can be calculated in the ECU0. That is, the fuel injection amount in one fuel injection opportunity is the amount required to set the air-fuel ratio to a predetermined value richer than the stoichiometric air-fuel ratio (less than 14.6), and multiplying this injection amount by the number of expansion strokes per unit time (proportional to the engine speed) gives the fuel supply amount per unit time. Then, multiplying the fuel supply amount per unit time by the elapsed time T R results in the total weight G of the supplied fuel F . In short, based on the elapsed time T R when the output signal of the air-fuel ratio sensor downstream of the catalyst indicates a rich air-fuel ratio, it is possible to calculate the maximum oxygen release capacity of the catalyst. This maximum oxygen release capacity is synonymous with the maximum oxygen storage capacity.

[0032] Strictly speaking, during the period of T R , due to the driver's accelerator operation or the like, the fuel supply amount per unit time (or the fuel injection amount in one injection) can increase or decrease. Therefore, the total weight G of the supplied fuel during the period of T R is preferably obtained by integrating the supply amount g F (t) per unit time over the range of T F . Also, in this embodiment, a linear A / F sensor is arranged upstream of the catalyst, and it is possible to measure the air-fuel ratio of the gas flowing into the catalyst in real time. Therefore, taking ΔA / F R as the difference between the stoichiometric air-fuel ratio and the measured air-fuel ratio measured via the A / F sensor, the maximum oxygen storage capacity of the catalyst can be obtained as the time integral during the period of T R . That is, R α∫{ΔA / F (t)·g R (t)}dt F Or, an internal combustion engine 1 ​From a state where an air-fuel ratio rich air-fuel mixture is supplied to the cylinder and the catalyst does not store any oxygen, active control is executed to intentionally operate the air-fuel mixture supplied to the cylinder to be air-fuel ratio lean. Then, the output signal of the air-fuel ratio sensor upstream of the catalyst immediately indicates an air-fuel ratio lean. In contrast, the output signal of the air-fuel ratio sensor downstream of the catalyst indicates an air-fuel ratio lean with a delay relative to the output signal of the upstream air-fuel ratio sensor. This is because excessive oxygen adsorbs onto the catalyst between the time when the output signal of the air-fuel ratio sensor upstream of the catalyst indicates an air-fuel ratio lean (or after the air-fuel mixture is operated to be air-fuel ratio lean) and the time when the output signal of the air-fuel ratio sensor downstream of the catalyst indicates an air-fuel ratio lean. Here, the air-fuel ratio sensor downstream of the catalyst is an O 2 sensor.

[0033] Let the time elapsed between the time when the output signal of the air-fuel ratio sensor upstream of the catalyst indicates an air-fuel ratio lean and the time when the output signal of the air-fuel ratio sensor downstream of the catalyst indicates an air-fuel ratio lean be T L , and let the total weight of the fuel supplied during this T L be G F , and let the difference between the air-fuel ratio during lean operation and the stoichiometric air-fuel ratio be ΔA / F L . Then, the amount of oxygen that becomes excessive in the catalyst during TL is (α·ΔA / F L ·G F ) .

[0034] The above equation represents the amount of oxygen stored in the catalyst at the time of T L . The total weight G F of the supplied fuel can also be calculated in the ECU0. That is, the fuel injection amount in one fuel injection opportunity is the amount necessary to set the air-fuel ratio to a predetermined value leaner than the stoichiometric air-fuel ratio (greater than 14.6), and multiplying this injection amount by the number of expansion strokes per unit time gives the fuel supply amount per unit time. Then, multiplying the fuel supply amount per unit time by the elapsed time T L gives the total weight G F of the supplied fuel. In short, it is possible to calculate the maximum oxygen storage capacity of the catalyst based on the elapsed time T L at the time when the output signal of the air-fuel ratio sensor downstream of the catalyst indicates an air-fuel ratio lean.

[0035] Strictly speaking, during T L the fuel supply amount per unit time (or the fuel injection amount per injection) may increase or decrease due to the driver's accelerator operation or the like. Therefore, during T L the total weight G of the supplied fuel F is preferably obtained by time-integrating the supply amount g F (t) within the range of T L . If ΔA / F L (t) is the difference between the theoretical air-fuel ratio and the measured air-fuel ratio measured via the A / F sensor, the maximum oxygen storage capacity of the catalyst can be obtained as the time integral during T L . That is, α∫{ΔA / F L (t)·g F (t)}dt As shown in FIG. 2, in active control, at the timing when the output signal of the air-fuel ratio sensor downstream of the catalyst reaches a predetermined rich determination value, that is, when the output switches from lean to rich, the control target air-fuel ratio is set to a predetermined air-fuel ratio on the lean side, and the fuel injection amount is corrected so that the output signal of the air-fuel ratio sensor upstream of the catalyst takes a value corresponding to the control target. Thereby, the air-fuel ratio of the gas flowing into the catalyst is forcibly made lean. Then, the elapsed time T L from when the output signal of the air-fuel ratio sensor upstream of the catalyst reaches the value corresponding to the control target until the output signal of the air-fuel ratio sensor downstream reaches the lean determination value, that is, the elapsed time T L until the output switches to lean again is measured.

[0036] Also, at the timing when the output of the air-fuel ratio sensor downstream of the catalyst switches from rich to lean, the control target air-fuel ratio is set to a predetermined air-fuel ratio on the rich side, and the fuel injection amount is corrected so that the output signal of the air-fuel ratio sensor upstream of the catalyst takes a value corresponding to the control target. Thereby, the air-fuel ratio of the gas flowing into the catalyst is forcibly made rich. Then, the elapsed time T RThat is, the elapsed time T until the output switches back to rich again R is measured.

[0037] ECU0 measures the time T required for the catalyst that had been storing oxygen until its oxygen storage capacity was full to release all of that oxygen R , and the time T required for the catalyst that was not storing oxygen to store oxygen until its oxygen storage capacity was full L one or more times each, and based on the measured Ts R T L calculates the maximum oxygen storage capacity (α·ΔA / F R ·G F ), (α·ΔA / F L ·G F ) and obtains their average value.

[0038] Note that after starting the active control, the maximum oxygen storage capacity is not calculated during the time period T until the output signal of the downstream air-fuel ratio sensor switches from lean to rich or from rich to lean for the first time 0 . This is because a part of the exhaust gas generated before the start of the active control also reaches the catalyst, making it impossible to accurately measure the oxygen storage capacity of the catalyst.

[0039] The determination of whether the catalyst has deteriorated is made by comparing the maximum oxygen storage capacity (the average of multiple estimated values) of the catalyst with a threshold value. That is, if the maximum oxygen storage capacity is less than the threshold value, it is diagnosed that the catalyst has already deteriorated and cannot exhibit sufficient performance. ECU0 that has determined that the catalyst has deteriorated stores information (diagnostic code) indicating the abnormality of the catalyst in the memory, and outputs and notifies the driver of the abnormality of the catalyst in a manner that appeals to the driver's vision or hearing. For example, it lights the engine check lamp in the cockpit, displays it on the display, or emits a warning sound to prompt inspection and replacement of the catalyst.

[0040] Here, as shown in FIG. 3 in the flow chart, the execution of the catalyst deterioration diagnosis control as described above is permitted only when the operating state of the internal combustion engine 1 is in a predetermined state. That is, when the operating state of the internal combustion engine 1 is other than the predetermined state, the execution of the catalyst deterioration diagnosis control is not permitted (step S1). The predetermined state is a state in which the intake air amount is equal to or more than a predetermined value and the operation (firing) of the internal combustion engine 1 can continue for a predetermined time or more. More specifically, for example, when starting the vehicle, when acceleration is required, when the operation of the heating device is required, when the operation of the defroster is required, or when the operation of the air conditioner is required. During starting and acceleration, the required load is high, and when operating the heating device, defroster, and air conditioner, in addition to driving the wheels, power is required to operate these devices, and it is expected that the operation (firing) of the internal combustion engine 1 will continue for a predetermined time or more. Moreover, for example, when the current coolant temperature of the internal combustion engine 1 is higher than a predetermined value, and the current accelerator opening, the intake air amount filled in the cylinder, the engine speed, the correction coefficient FAF by air-fuel ratio feedback control, and the temperature of the catalyst are respectively within a predetermined range, etc., when all other conditions for executing the catalyst deterioration diagnosis control are satisfied (step S2), the catalyst deterioration diagnosis control is executed (step S3). The current temperature of the catalyst can be directly measured if a temperature sensor for detecting this is installed, but otherwise, it is estimated based on the cumulative value of the intake air amount, the cumulative value of the fuel injection amount, the current coolant temperature of the internal combustion engine 1 since starting, etc. 1 It is preferable to execute the catalyst deterioration diagnosis control at least once per trip (the period from when the ignition switch is turned ON to start the internal combustion engine until the ignition switch is turned OFF to stop the internal combustion engine).

[0041] That is, under the condition that the execution conditions of the catalyst deterioration diagnosis control are satisfied, as shown in FIG. 2, the internal combustion engine

[0042] 1 ​When the operating state reaches a predetermined state, active control of the air-fuel ratio is started, and the calculation of the maximum oxygen storage capacity is not performed during a predetermined time period T. 0 Thereafter, the time T required for the catalyst that had stored oxygen until its oxygen storage capacity was full to release all of that oxygen, R and the time T required for a catalyst that has not stored oxygen to store oxygen until its oxygen storage capacity is full L are measured. Here, the operating state "X" in FIG. 2 indicates that the operating state of the internal combustion engine is not in a predetermined state, and "Y" indicates that the operating state of the internal combustion engine is in a predetermined state.

[0043] As described above, according to the present embodiment, in a hybrid vehicle, when the operation of the internal combustion engine 1 is not expected to continue for a predetermined time or more, the execution of the catalyst deterioration diagnosis control is not permitted. Therefore, during the execution of the catalyst deterioration diagnosis control, if the operation (firing) of the internal combustion engine 1 stops and the operation of the internal combustion engine 1 is restarted, and the catalyst deterioration diagnosis control is executed again, active control without calculating the maximum oxygen storage capacity is performed, and by increasing the period during which the active control is performed, it is possible to prevent or suppress the occurrence of problems such as deterioration of fuel consumption and exhaust gas.

[0044] Note that the present invention is not limited to the embodiments described above.

[0045] For example, the condition for permitting the catalyst deterioration diagnosis control may be arbitrarily set other than those shown in the above-described embodiment as long as the operation (firing) of the internal combustion engine is expected to continue for a sufficiently long period without interruption during the execution of the catalyst deterioration diagnosis control.

[0046] In addition, the present invention may be applied to the control of hybrid vehicles other than series-type hybrid vehicles.

[0047] Furthermore, various modifications may be made without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0048] 0 … Control device 1 … Internal combustion engine 14 … Exhaust passage 141 … Catalyst (three-way catalyst) 4 … Traction motor (traction motor generator)

Claims

1. It is used in a hybrid vehicle equipped with an internal combustion engine and an electric motor as power sources, estimating the oxygen storage capacity of a catalyst for purifying exhaust gas mounted in the exhaust passage of the internal combustion engine, and diagnosing whether the catalyst is deteriorated by determining whether the oxygen storage capacity is equal to or greater than a threshold value, A control device for a hybrid vehicle that performs catalyst deterioration diagnosis control, A period during which the estimation of the oxygen storage amount of the catalyst is not performed is set immediately after the start of the catalyst deterioration diagnosis control, When the operating state of the internal combustion engine is a predetermined state, the execution of the catalyst deterioration diagnosis control is permitted, and the predetermined state is a state in which the intake air amount into the cylinders of the internal combustion engine is equal to or greater than a predetermined value and the firing operation of the internal combustion engine can be continued for a predetermined time or more. A control device for a hybrid vehicle that does not permit the execution of the catalyst deterioration diagnosis control when the operating state of the internal combustion engine is other than the predetermined state.

2. The control device for a hybrid vehicle according to claim 1, wherein the predetermined state includes at least one of a case where the vehicle starts, a case where acceleration is required, a case where the operation of a heating device is required, a case where the operation of a defroster is required, or a case where the operation of a cooling device is required.

Images