Vehicle fault diagnosis device

Abstract

To provide a vehicle failure diagnosis device capable of securing a diagnostic failure opportunity of an exhaust component while minimizing discomfort imparted to an occupant.SOLUTION: A vehicle failure diagnosis device comprises: a residual capacity detection unit that detects a residual capacity of a battery; a travel control unit that, upon a predetermined motor mode execution condition being satisfied, stops an engine and starts to drive a motor; and a fault diagnosis unit that, during a state with the engine being driven and a predetermined diagnosable condition satisfied, determines whether or not an exhaust component is faulty. When the motor mode execution condition is satisfied during the state with the engine being driven and the predetermined diagnosable condition satisfied, the fault diagnosis unit executes drive continuation control to continue driving the engine until a predetermined continuation period elapses after the motor mode execution condition is satisfied, and sets the continuation period to a period shorter when the residual capacity of the battery detected by the residual capacity detection unit is larger than when small.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a vehicle fault diagnosis device.

Background Art

[0002] The engine is provided with various components. In a vehicle equipped with an engine, etc., it is determined whether these components are faulty, that is, fault diagnosis is performed. Fault diagnosis is also required in a hybrid vehicle equipped with an engine and a motor. However, in a hybrid vehicle, the engine is often stopped. Therefore, in a hybrid vehicle, there is a problem that the opportunity to perform fault diagnosis of components that can only be fault diagnosed when exhaust gas is flowing through the exhaust passage is reduced.

[0003] In contrast, for example, Patent Document 1 discloses a vehicle that performs fault diagnosis of a sensor provided in an exhaust passage, and when conditions for performing the fault diagnosis of the sensor are satisfied, the engine is prohibited from stopping until the fault diagnosis is completed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the configuration described in Patent Document 1, the engine cannot be stopped until the fault diagnosis is complete, which may cause discomfort to the vehicle's occupants. Specifically, in hybrid vehicles equipped with both a motor and an engine as drive sources, there are known vehicles that primarily stop the engine and drive the motor when the battery capacity is large. Therefore, if the configuration described in Patent Document 1 is adopted in such a vehicle, the occupants may feel uncomfortable because the engine is not stopped even though the battery capacity is large.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a vehicle fault diagnosis device that can ensure opportunities for fault diagnosis of exhaust components while minimizing discomfort to the occupants. [Means for solving the problem]

[0007] The present invention relates to a vehicle fault diagnosis device comprising a motor as a drive source, an engine having an engine body in which a combustion chamber is formed and an exhaust passage connected thereto, and a battery that supplies power to the motor, wherein the vehicle fault diagnosis device comprises a remaining capacity detection unit that detects the remaining capacity of the battery, a driving control unit that stops the engine and drives the motor when predetermined motor mode implementation conditions are met, and a fault diagnosis unit that determines whether or not an exhaust component provided in the exhaust passage is faulty while the engine is running and predetermined diagnostic conditions are met, wherein the fault diagnosis unit, when the motor mode implementation conditions are met while the engine is running and the diagnostic conditions are met, performs driving continuation control to continue driving the engine for a predetermined duration elapsed from the time the motor mode implementation conditions are met, and sets the duration to be shorter when the remaining capacity of the battery detected by the remaining capacity detection unit is large than when it is small.

[0008] According to the fault diagnosis device of the present invention, even when the motor mode implementation condition, which is the condition for stopping the engine and driving the motor, is met, the engine will be forcibly continued to run if a fault diagnosis of the exhaust components is possible. Therefore, the opportunities for fault diagnosis of the exhaust components can be increased. Moreover, with this device, when the remaining battery capacity is large, the time during which the engine is forcibly continued to run after the motor mode implementation condition is met is shortened. In other words, when the remaining battery capacity is large and the occupants are likely to expect the engine to stop and the motor to run, the time from engine stop to motor start-up is shortened. Also, when the remaining battery capacity is small and the occupants are less likely to feel uncomfortable that the engine is not stopped, the engine will continue to run for a relatively long period of time. Therefore, the opportunities for fault diagnosis of the exhaust components can be increased while minimizing the discomfort caused to the occupants.

[0009] In the above configuration, preferably, a plurality of the exhaust components are provided, the diagnostic conditions are set individually for each of the exhaust components, and the fault diagnosis unit performs the drive continuation control when the motor mode implementation condition is met while the engine is running and all of the diagnostic conditions are met (Claim 2).

[0010] In this configuration, drive continuation control is implemented when fault diagnosis of multiple exhaust components is possible. Therefore, it is possible to ensure opportunities for fault diagnosis of multiple exhaust components while minimizing the opportunities for the engine to be forcibly driven under conditions for motor mode implementation.

[0011] In the above configuration, the exhaust components include a purification device provided in the exhaust passage for purifying exhaust gas, an upstream sensor provided upstream of the purification device for detecting the properties of the exhaust gas, and a downstream sensor provided downstream of the purification device for detecting the properties of the exhaust gas (Claim 3).

[0012] In the above configuration, preferably, when the fault diagnosis unit completes the determination of whether or not the exhaust component is faulty while the drive continuation control is being performed, it stops the drive continuation control, stops the engine and drives the motor (Claim 4).

[0013] With this configuration, when it is no longer necessary to keep the engine running for fault diagnosis, the engine stops and the motor starts running in accordance with the conditions for motor mode implementation. Therefore, it is possible to shorten the time during which the engine is forcibly run when the conditions for motor mode implementation are met, while still ensuring an opportunity for fault diagnosis. [Effects of the Invention]

[0014] According to the vehicle fault diagnosis device of the present invention, it is possible to ensure an opportunity to diagnose faults in exhaust components while minimizing discomfort to the occupants. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a block diagram showing a schematic configuration of a vehicle to which a fault diagnosis device according to an embodiment of the present invention is applied. [Figure 2] This is a block diagram of the vehicle's control system. [Figure 3] This is a flowchart showing the procedure for switching between driving modes. [Figure 4] This is a flowchart showing the procedure for diagnosing a malfunction. [Figure 5] This is a flowchart showing the procedure for deciding whether to request continued engine operation. [Figure 6] This diagram shows the relationship between the battery's State of Charge (SOC) and the judgment time. [Figure 7] This is a time chart that schematically shows the time changes of each parameter when a request to continue engine operation is issued. [Modes for carrying out the invention]

[0016] A preferred embodiment of the present invention will be described below with reference to the drawings.

[0017] (Overall Configuration) FIG. 1 is a block diagram showing a schematic configuration of a vehicle to which a fault diagnosis apparatus according to the present invention is applied. This vehicle is a hybrid vehicle. Hereinafter, this vehicle is referred to as HV vehicle 1. HV vehicle 1 includes an engine 2 and a motor 4 as driving sources for traveling, a transmission 6, a first clutch 15, a second clutch 16, wheels 10, an inverter 12, a battery 14, and a controller 100.

[0018] The engine 2 is an internal combustion engine that generates driving force by burning a mixture of fuel and air. In the present embodiment, the engine 2 is a gasoline engine that uses fuel mainly composed of gasoline. The engine 2 includes an engine body 30 in which cylinders are formed, an intake passage 40 through which intake air (air) introduced into the engine body 30 flows inside, and an exhaust passage 50 through which exhaust gas derived from the engine body 30 flows inside. The engine body 30 is a four-cycle engine.

[0019] The engine body 30 has a cylinder block 31 in which cylinders 33 are formed inside, and a cylinder head 32 attached to the upper surface of the cylinder block 31. For example, the engine body 30 is an in-line six-cylinder engine having six cylinders arranged in a row.

[0020] Pistons 34 are respectively fitted in each cylinder 33 so as to be reciprocable in the vertical direction. A combustion chamber 35 is defined between the crown surface of the piston 34 and the inner peripheral surface of the cylinder 33. The piston 34 is connected to a crankshaft 36, and the crankshaft 36 rotates when the piston 34 reciprocates by receiving combustion energy generated in the combustion chamber 35.

[0021] The engine body 30 is equipped with an injector 37 that injects fuel into the combustion chamber 35. Although Figure 1 shows a case where a side-injection type injector that injects fuel into the combustion chamber 35 from the side is used as the injector 37, the injector 37 is not limited to a side-injection type. The engine body 30 is equipped with a spark plug 38 that ignites the fuel-air mixture formed in the combustion chamber 35.

[0022] The cylinder block 31 is equipped with a crank angle sensor SN1 for detecting the rotation angle of the crankshaft 36 and, consequently, the engine speed. The cylinder head 32 is equipped with a water temperature sensor SN2 for detecting the engine water temperature, which is the temperature of the engine coolant that cools the engine body 30. Specifically, the engine body 30 has a water jacket (not shown) through which engine coolant flows, and the water temperature sensor SN2 detects the temperature of the engine coolant flowing through the water jacket.

[0023] The intake passage 40 is connected to the engine body 30 in communication with each combustion chamber 35. The intake passage 40 is equipped with a throttle valve 41 that opens and closes the intake passage 40 to adjust the flow rate of intake air flowing through it. The intake passage 40 is also equipped with an airflow sensor SN3 that detects the flow rate of intake air flowing through it. In the example shown in Figure 1, the airflow sensor SN3 is located upstream of the throttle valve 41.

[0024] The exhaust passage 50 is connected to the engine body 30 in communication with each combustion chamber 35. The exhaust passage 50 is provided with a purification device 52 for purifying the exhaust gas, which is the burnt gas discharged from each combustion chamber 35. In this embodiment, the purification device 52 has a catalyst and purifies the exhaust gas through the action of the catalyst. The purification device 52 has, for example, a three-way catalyst.

[0025] The exhaust passage 50 is provided with a catalyst temperature sensor SN4 for detecting the temperature of the purification device 52, that is, the temperature of the catalyst built into the purification device 52. The portion of the exhaust passage 50 upstream of the purification device 52 is provided with a front O2 sensor SN5 for detecting the oxygen concentration of the exhaust gas passing through that portion. The portion of the exhaust passage 50 downstream of the purification device 52 is provided with a rear O2 sensor SN6 for detecting the oxygen concentration of the exhaust gas passing through that portion. In this embodiment, the front O2 sensor SN5 corresponds to the "upstream sensor" of the present invention, and the oxygen concentration of the exhaust gas detected by the front O2 sensor SN5 corresponds to the properties of the exhaust gas detected by the "upstream sensor". Also in this embodiment, the rear O2 sensor SN6 corresponds to the "downstream sensor" of the present invention, and the oxygen concentration of the exhaust gas detected by the rear O2 sensor SN6 corresponds to the properties of the exhaust gas detected by the "downstream sensor". Furthermore, in this embodiment, the front O2 sensor SN5 is a so-called LAFS and detects the oxygen concentration itself, while the rear O2 sensor SN6 detects the presence or absence of oxygen in the exhaust gas.

[0026] Motor 4 is, for example, a three-phase AC synchronous motor generator. Engine 2 and motor 4 are connected via a first clutch 15. The first clutch 15 disconnects the crankshaft 36 of engine 2 and the rotating shaft (rotor shaft, not shown) of motor 4. Specifically, the first clutch 15 switches the state of engine 2 and motor 4 between a connected state in which torque is transmitted between them and a disconnected state in which torque is not transmitted. More specifically, when the first clutch 15 is engaged, the state of engine 2 and motor 4 becomes a connected state in which torque is transmitted between them, and when the first clutch 15 is disengaged (released), the state of engine 2 and motor 4 becomes a disconnected state in which torque is not transmitted between them.

[0027] The transmission 6 changes the input rotation speed and outputs it. For example, a transmission 6 with 6 forward speeds and 1 reverse speed may be used. The output shaft of the transmission 6 is connected to the wheel 10 via a differential gear 8, and the rotational force input to the transmission 6 is transmitted to the wheel 10.

[0028] The input shaft of the transmission 6 is connected to the motor 4 via the second clutch 16. Specifically, the input shaft of the transmission 6 and the rotating shaft of the motor 4 are connected via the second clutch 16. The second clutch 16 intermittently connects the rotating shaft of the motor 4 and the input shaft of the transmission 6. Specifically, the second clutch 16 switches the state between the rotating shaft of the motor 4 and the input shaft of the transmission 6 between a connected state in which torque is transmitted between them and a disconnected state in which torque is not transmitted.

[0029] As described above, the rotating shaft of the motor 4 and the crankshaft 36 of the engine 2 are connected via the first clutch 15, and torque can be transmitted between the crankshaft 36 and the input shaft of the transmission 6 via the rotating shaft of the motor 4. Accordingly, the HV vehicle 1 can run in three modes: a motor mode in which it runs solely on the driving force of the motor 4, a combined mode in which it runs on the driving force of both the motor 4 and the engine 2, and an engine mode in which it runs solely on the driving force of the engine 2. Specifically, when the first clutch 15 is disengaged and the second clutch 16 is engaged, only the driving force of the motor 4 is transmitted to the wheels 10. On the other hand, when both the first clutch 15 and the second clutch 16 are engaged, and the motor 4 does not generate driving force (when the power supply to the motor 4 is cut off), only the driving force of the engine 2 is applied to the wheels 10 via the transmission 6, etc. Furthermore, when both the first clutch 15 and the second clutch 16 are engaged and the motor 4 is generating driving force, the output of the engine 2 and the motor 4 is applied to the wheels 10 via the transmission 6, etc. In addition, the HV vehicle 1 in this embodiment is a vehicle capable of regenerative braking, and the motor 4 is configured to generate electricity from the rotational force transmitted from the wheels 10 when the HV vehicle 1 is decelerating. At this time, a braking force corresponding to the electricity generated by the motor 4 acts on the wheels 10.

[0030] Battery 14 is a rechargeable secondary battery. For example, a lithium-ion battery or a nickel-metal hydride battery can be used as battery 14. The motor 4 and battery 14 are electrically connected via inverter 12. Inverter 12 converts between three-phase AC power and DC power. Power is supplied to the motor 4 from battery 14 via inverter 12, and the motor 4 rotates and generates driving force in response to this power. The power generated by the motor 4 is also supplied to battery 14 via inverter 12 and stored in battery 14.

[0031] Battery 14 is equipped with a battery sensor SN7 that detects the input and output current to and from the battery 14. As will be described later, the current value detected by the battery sensor SN7 is used to detect the battery SOC. Battery SOC is the ratio of the current charge amount to the charge amount when battery 14 is fully charged, that is, the remaining capacity of battery 14. In other words, battery sensor SN7 is a sensor for detecting battery SOC (remaining capacity of battery 14) and corresponds to the "remaining capacity detection unit" of the present invention.

[0032] (Control system) The control configuration of the HV vehicle 1 will be explained based on the block diagram in Figure 2. The HV vehicle 1 is centrally controlled by the controller 100. The controller 100 consists of a CPU, ROM, RAM, etc.

[0033] The controller 100 receives sequential detection signals from various sensors mounted on the HV vehicle 1, including the sensors SN1 to SN7 mentioned above. The HV vehicle 1 is equipped with an accelerator position sensor SN8 that detects the accelerator position, which is the amount the accelerator pedal is pressed, and the detection signal from the accelerator position sensor SN8 is also input to the controller 100. The controller 100 performs various judgments and calculations based on the information input from each sensor SN1 to SN8, etc. For example, the controller 100 calculates the charge and discharge rates of the battery 14 per unit time based on the detection value of the battery sensor SN7, and calculates the battery SOC by integrating these values. The controller 100 also calculates the output required for the HV vehicle 1 based on the detection value of the accelerator position sensor SN8. The controller 100 then outputs control signals to each part of the HV vehicle 1, such as the motor 4 (inverter 12), engine 2 (throttle valve 41, injector 37, spark plug 38), first clutch 15, and second clutch 16, based on the calculation results, and controls them accordingly.

[0034] The controller 100 operates functionally to include a driving control unit 110 and a fault diagnosis unit 120 when a predetermined program is executed. The fault diagnosis unit 120 also operates functionally to include a diagnosis execution unit 121 and a continuation request determination unit 122.

[0035] (Driving control unit) The driving control unit 110 determines the driving mode of the HV vehicle 1 and performs control to switch between them. Figure 3 is a flowchart of the procedure for switching between driving modes.

[0036] The driving control unit 110 first reads various information detected by sensors SN1 to SN8, etc. (step S1).

[0037] Next, the driving control unit 110 determines whether the motor mode implementation conditions, which are the conditions for switching the driving mode to motor mode or maintaining the driving mode in motor mode, are met (step S2). The motor mode implementation conditions are set in advance. For example, the motor mode implementation conditions include the conditions that the battery SOC is equal to or greater than a preset mode determination value and that the vehicle HV1 is not undergoing rapid acceleration. The driving control unit 110 makes the above determination based on the battery SOC and the accelerator opening detected by the accelerator opening sensor SN8.

[0038] If the determination in step S2 is NO and the motor mode implementation condition is not met, the driving control unit 110 determines whether the combined mode implementation condition, which is the condition for switching the driving mode to combined mode or maintaining the driving mode in combined mode, is met (step S6). The combined mode implementation condition is set in advance. For example, the combined mode implementation condition includes the condition that the battery SOC is equal to or greater than the above mode determination value, and the driving control unit 110 makes the above determination based on the battery SOC, etc.

[0039] If the determination in step S6 is YES and the conditions for implementing the combined mode are met, the driving control unit 110 controls each part so that the driving mode of the HV vehicle 1 becomes the combined mode (step S7). Specifically, the driving control unit 110 drives both the motor 4 and the engine 2 and engages the first clutch 15. If both the motor 4 and the engine 2 are already driven, this state is maintained. Also, if the first clutch 15 is already engaged, this state is maintained. After step S7, the driving control unit 110 terminates its processing (returns to step S1).

[0040] On the other hand, if the determination in step S6 is NO and the conditions for implementing the combined mode are not met, the driving control unit 110 controls each part so that the driving mode of the HV vehicle 1 becomes engine mode (step S8). Specifically, the driving control unit 110 stops the motor 4, drives the engine 2, and engages the first clutch 15. If the motor 4 is already stopped, it is maintained in this state, and if the engine 2 is already running, it is maintained in this state. Also, if the first clutch 15 is already engaged, it is maintained in this state. After step S8, the driving control unit 110 terminates its processing (returns to step S1).

[0041] Returning to step S2, if the determination in step S2 is YES and the motor mode implementation conditions are met, the driving control unit 110 then determines whether or not there is a request to continue engine driving (step S3). Details of the request to continue engine driving will be described later, but this request is output from the continuation request determination unit 122, and in step S3, it is determined whether or not the continuation request determination unit 122 has output an engine driving continuation request.

[0042] If the determination in step S3 is YES and there is no request to continue engine operation (no engine continuation request is output from the continuation request determination unit 122), the driving control unit 110 controls each part so that the driving mode of the HV vehicle 1 becomes motor mode (step S4). Specifically, the driving control unit 110 drives the motor 4 while stopping the engine 2 and disengaging the first clutch 15. If the motor 4 is already running, it is maintained, and if the engine 2 is already stopped, it is maintained. Also, if the first clutch 15 is already disengaged, it is maintained. After step S4, the driving control unit 110 terminates processing (returns to step S1).

[0043] On the other hand, if the determination in step S3 is NO and there is a request to continue engine drive (if the continuation request determination unit 122 outputs an engine continuation request), the driving control unit 110 continues to drive the engine 2 and continues to connect the first clutch 15 (step S5), and then terminates the process (returns to step S1). In other words, as will be described later, an engine drive continuation request is output when the driving mode is the combined mode or the engine mode. Therefore, if there is an engine drive continuation request, even if the motor mode implementation conditions are met, the driving control unit 110 continues to drive the engine 2 and continues to connect the first clutch 15 without switching the driving mode to the motor mode, while continuing the current driving mode (combined mode or engine mode).

[0044] (Diagnostic Execution Unit) The diagnostic execution unit 121 determines whether or not the exhaust components, which are parts provided in the exhaust passage 50, are malfunctioning, that is, it performs a fault diagnosis. In this embodiment, the diagnostic execution unit 121 performs fault diagnoses on the front O2 sensor SN5, the rear O2 sensor SN6, and the purification device 52.

[0045] The diagnostic execution unit 121 performs fault diagnosis on each of the three exhaust components (front O2 sensor SN5, rear O2 sensor SN6, and purification device 52) individually. However, the overall flow of the diagnostic procedure is the same for each component. First, the overall flow of the fault diagnosis performed by the diagnostic execution unit 121 will be explained using the flowchart in Figure 4.

[0046] First, the diagnostic execution unit 121 determines whether the engine 2 is running, that is, whether the driving mode of the HV vehicle 1 is engine mode or combined mode (step S11). If the determination in step S11 is NO and the engine 2 is stopped, the diagnostic execution unit 121 terminates processing without performing fault diagnosis (returns to step S11). On the other hand, if the determination in step S11 is YES and the engine 2 is running, the diagnostic execution unit 121 reads various information detected by sensors SN1 to SN8, etc. (step S12). Next, the diagnostic execution unit 121 determines whether the diagnostic conditions are met (step S13). If the determination in step S13 is NO and the diagnostic conditions are not met, the diagnostic execution unit 121 terminates processing without performing fault diagnosis (returns to step S11). On the other hand, if the determination in step S13 is YES and the diagnostic conditions are met, the diagnostic execution unit 121 further determines whether the diagnostic execution conditions are met (step S14).

[0047] If the determination in step S14 is NO and the diagnostic execution conditions are not met, the diagnostic execution unit 121 terminates the process without performing a fault diagnosis (returns to step S11). On the other hand, if the determination in step S14 is YES and the diagnostic execution conditions are met, the diagnostic execution unit 121 calculates the determination parameters (step S15). Next, the diagnostic execution unit 121 determines whether the calculation of the determination parameters has been completed (step S16). If the determination in step S16 is NO and the calculation of the determination parameters has not been completed, the diagnostic execution unit 121 returns to step S14. In other words, as long as the diagnostic execution conditions are met, the diagnostic execution unit 121 waits for the calculation of the determination parameters to be completed. On the other hand, if the determination in step S16 is YES and the calculation of the determination parameters has been completed, the diagnostic execution unit 121 determines whether the exhaust components are faulty based on the determination parameters (step S17). If the determination in step S17 is NO and it is determined that the exhaust components are not faulty, the diagnostic execution unit 121 terminates the process (returns to step S11). On the other hand, if the determination in step S17 is YES and it is determined that the exhaust component is malfunctioning, the diagnostic execution unit 121 stores the malfunction (step S18). Furthermore, if the diagnostic execution unit 121 determines that the exhaust component is malfunctioning, it may also notify the occupants of the HV vehicle 1 of this fact.

[0048] In this embodiment, the diagnostic conditions described above are set to be the same for all three exhaust components (front O2 sensor SN5, rear O2 sensor SN6, and purification device 52). Specifically, the diagnostic conditions are set to the condition that fuel cut has occurred, that is, that fuel injection from the injector 37 to the combustion chamber 35 has stopped due to deceleration of the HV vehicle 1, etc. Therefore, in the fault diagnosis of any of the three exhaust components, a determination is made in step S14 above as to whether or not fuel cut has occurred.

[0049] On the other hand, the diagnostic conditions described above are set differently for each of the three exhaust components (front O2 sensor SN5, rear O2 sensor SN6, and purification device 52). Specifically, the diagnostic conditions for the front O2 sensor SN5 include the condition that the engine water temperature detected by the water temperature sensor SN2 is above a predetermined water temperature. The diagnostic conditions for the rear O2 sensor SN6 include the condition that the output voltage of the rear O2 sensor SN6 is above a predetermined voltage. The diagnostic conditions for the purification device 52 include the condition that the catalyst temperature detected by the catalyst temperature sensor SN4 is above a predetermined temperature. Hereinafter, the diagnostic conditions for the front O2 sensor SN5 will be referred to as the front O2 diagnostic conditions, the diagnostic conditions for the rear O2 sensor SN6 will be referred to as the rear O2 diagnostic conditions, and the diagnostic conditions for the purification device 52 will be referred to as the catalyst diagnostic conditions.

[0050] Furthermore, the specific determination details based on the above-mentioned determination parameters and the determination parameters performed in step S17 are set individually according to each exhaust component (front O2 sensor SN5, rear O2 sensor SN6, purification device 52).

[0051] Specifically, it is known that when the front O2 sensor SN5 malfunctions (deteriorates), the rate of change of the output voltage of the front O2 sensor SN5 in response to changes in the oxygen concentration of the exhaust gas decreases, and this can be used to determine if the front O2 sensor SN5 is malfunctioning. Accordingly, for the front O2 sensor SN5, the maximum value of the rate of change of the output voltage of the front O2 sensor SN5 at the start of fuel cut and at the end of fuel cut (when fuel injection from the injector 37 resumes) are set as parameters for determination. The diagnostic execution unit 121 then calculates the maximum values ​​of the rate of change of the output voltage at the start and end of fuel cut, and if at least one of these is smaller than a predetermined value, it determines that the front O2 sensor SN5 is malfunctioning.

[0052] Furthermore, it has been found that when the rear O2 sensor SN6 malfunctions (deteriorates), the time during which the output voltage of the rear O2 sensor SN6 remains within a predetermined range when the oxygen concentration of the exhaust gas being detected changes increases. This can be used to determine if the rear O2 sensor SN6 is malfunctioning. Accordingly, for the rear O2 sensor SN6, the time during which the output voltage of the rear O2 sensor SN6 remains within a predetermined range at both the start and end of the fuel cut is set as a determination parameter. The diagnostic execution unit 121 then calculates these times at the start and end of the fuel cut and determines that the rear O2 sensor SN6 is malfunctioning if at least one of them is longer than a predetermined value.

[0053] Furthermore, it is known that if the purification device 52 malfunctions, the amount of oxygen stored in the purification device 52 during fuel cut-off decreases, and consequently, the amount of fuel that reacts with the oxygen stored in the purification device 52 also decreases. This can be used to determine if the purification device 52 is malfunctioning. Accordingly, for the purification device 52, the amount of fuel introduced into the purification device 52 from the end of fuel cut-off until the oxygen in the purification device 52 is depleted is set as a determination parameter. The diagnostic execution unit 121 then calculates the above fuel amount, and if it is less than a predetermined amount, it determines that the purification device 52 is malfunctioning. Specifically, the diagnostic execution unit 121 estimates the amount of fuel introduced into the purification device 52 based on the oxygen concentration detected by the front O2 sensor SN5 from the end of fuel cut-off until the output voltage of the rear O2 sensor SN6 exceeds a predetermined voltage. If this estimated fuel amount is less than a predetermined value, it determines that the purification device 52 is malfunctioning.

[0054] (Decision-making department for continuing requests) The continuation request determination unit 122 determines whether or not to output an engine drive continuation request to the driving control unit 110, which is used in the determination of step S3 shown in Figure 3. Figure 5 is a flowchart showing the procedure for determining the engine drive continuation request.

[0055] The continuation request determination unit 122 first determines whether the engine 2 is running and the first clutch 15 is engaged, that is, whether the driving mode of the HV vehicle 1 is engine mode or combined mode (step S21). If the determination in step S21 is NO, and the driving mode is motor mode, and the engine 2 is stopped or the first clutch 15 is disengaged, the continuation request determination unit 122 terminates processing without issuing an engine drive continuation request (returns to step S21).

[0056] On the other hand, if the determination in step S21 is YES and the engine 2 is running and the first clutch 15 is engaged, the continuation request determination unit 122 determines whether or not the motor mode implementation conditions are met (step S22). If the determination in step S22 is NO and the motor mode implementation conditions are not met, the continuation request determination unit 122 terminates processing without issuing an engine drive continuation request (returns to step S21). On the other hand, if the determination in step S22 is YES and the motor mode implementation conditions are met, the continuation request determination unit 122 reads various information detected by sensors SN1 to SN8, etc. (step S23).

[0057] Here, step S22 is performed when the determination in step S21 is YES and the driving mode is engine mode or combined mode. Thus, in step S22, it is determined whether the conditions for implementing motor mode have been met while the driving mode is engine mode or combined mode. If the conditions for implementing motor mode have been met while the driving mode is engine mode or combined mode, then steps S23 and onward will be performed.

[0058] Following step S23, the continuation request determination unit 122 determines whether all diagnostic conditions are met (step S24). Specifically, the continuation request determination unit 122 determines whether all of the above conditions for front O2 diagnostics, rear O2 diagnostics, and catalyst diagnostics are met.

[0059] If the determination in step S24 is NO and one or more diagnostic conditions are not met, the continuation request determination unit 122 terminates processing without outputting an engine drive continuation request (returns to step S21).

[0060] On the other hand, if the determination in step S24 is YES and all diagnostic conditions are met, the continuation request determination unit 122 sets the determination time to be used for the determination in step S28, which will be described later (step S25).

[0061] The continuation request determination unit 122 sets the determination time based on the battery SOC. Specifically, the continuation request determination unit 122 sets the determination time so that it is shorter when the battery SOC is large than when it is small. The above determination time corresponds to the "continuation period" of the present invention.

[0062] In this embodiment, the determination time for the battery SOC is pre-set as shown in Figure 6 and stored in the controller 100. In the graph in Figure 6, the horizontal axis is battery SOC (%) and the vertical axis is the determination time. In this embodiment, as shown in Figure 6, when the battery SOC is less than or equal to a predetermined first SOC (X1), the determination time is set to a predetermined first time T1 regardless of the battery SOC. Also, when the battery SOC is greater than or equal to a second SOC (X2) which is greater than the first SOC (X1), the determination time is set to a second time T2 which is shorter than the first time T1, regardless of the battery SOC. Furthermore, when the battery SOC is greater than the first SOC (X1) and less than the second SOC (X2), the determination time is set between the first time T1 and the second time T2 such that the determination time decreases as the battery SOC increases. In the example in Figure 6, the determination time is shortened in proportion to the battery SOC. In other words, when the battery SOC is greater than the first SOC (X1) and less than the second SOC (X2), the determination time is shortened from the first time T1 in proportion to the amount by which the battery SOC exceeds the first SOC, and so that the determination time when the battery SOC is the second SOC becomes the second time T2.

[0063] Returning to the flowchart in Figure 5, after setting the judgment time in step S25, the continuation request determination unit 122 outputs an engine drive continuation request (step S26).

[0064] Here, step S26 is performed when the determination in step S22 is YES, and the engine drive continuation request is output when the motor mode implementation condition is met. Therefore, when the engine drive continuation request is output, the determination in step S2 in the flowchart of Figure 3 is YES. Accordingly, when the engine drive continuation request is output, the driving control unit 110 performs step S5 described above. In other words, as described above, when the engine drive continuation request is output, the driving control unit 110 continues to drive the engine 2 and continues to disengage the first clutch 15 without switching the driving mode to motor mode, even though the motor mode implementation condition has been met. In other words, the continuation request determination unit 122 instructs the driving control unit 110 to continue the current driving mode (combined mode or engine mode), prohibiting the stopping of the engine 2 and prohibiting the disengagement of the first clutch 15.

[0065] After step S26, the continuation request determination unit 122 determines whether all diagnostic conditions are currently met (step S27). If the determination in step S27 is NO and one or more diagnostic conditions are no longer met, the continuation request determination unit 122 withdraws the engine drive continuation request (step S30). Once the engine drive continuation request is withdrawn, the drive control unit 110 can switch the drive mode to motor mode. Therefore, if the motor mode implementation conditions are met, the drive control unit 110 drives the motor 4, stops the engine E, and disengages the first clutch 15. In other words, as long as the motor mode implementation conditions are met, the continuation request determination unit 122 causes the drive control unit 110 to drive the motor 4, stop the engine 2, and disengage the first clutch 15.

[0066] Returning to step S27, if the determination in step S27 is YES and all diagnostic conditions continue to be met, the continuation request determination unit 122 determines whether the elapsed time since the engine drive continuation request was issued is less than or equal to the determination time (step S28).

[0067] If the determination in step S28 is NO and the elapsed time since the request to continue driving has exceeded the determination time, the continuation request determination unit 122 proceeds to step S30 and withdraws the engine drive continuation request. After that, the continuation request determination unit 122 terminates processing (returns to step S21).

[0068] On the other hand, if the determination in step S28 is YES and the elapsed time since the request to continue driving was issued is less than or equal to the determination time, the continuation request determination unit 122 determines whether all fault diagnoses have been completed (step S29). Specifically, the continuation request determination unit 122 determines whether all diagnostic conditions have been met and whether a determination has been made thereafter regarding whether the front O2 sensor SN5, the rear O2 sensor SN6, and the purification device 52 are faulty.

[0069] If the determination in step S29 is NO and any fault diagnosis is incomplete, the continuation request determination unit 122 returns to step S26, continues to issue an engine drive continuation request, and performs the steps from step S26 onward.

[0070] On the other hand, if the determination in step S29 is YES and all fault diagnoses are completed, the continuation request determination unit 122 proceeds to step S30 and withdraws the engine drive continuation request. After that, the continuation request determination unit 122 terminates processing (returns to step S21).

[0071] As described above, when the motor mode implementation condition is met while the engine 2 is running and all diagnostic conditions are met, the controller 100 implements a drive continuation control, which is a control that continues to run the engine 2 from the time the motor mode implementation condition is met until the judgment time has elapsed. Furthermore, when all fault diagnoses are completed while the drive continuation control that continues to run the engine 2 is being implemented, the controller 100 stops the drive continuation control, switches the driving mode to motor mode, stops the engine 2, and starts running the motor 4.

[0072] Figure 7 is a time chart that schematically shows the time changes of each parameter when an engine drive continuation request is output. From top to bottom, Figure 7 shows the time changes of the following parameters: success or failure of the motor mode implementation condition, engine drive state and first clutch state, catalyst temperature, success or failure of the catalyst diagnostic conditions, engine water temperature, success or failure of the front O2 diagnostic conditions, voltage of the rear O2 sensor SN6, rear O2 diagnostic conditions, and the output state of the engine drive continuation request.

[0073] In the example shown in Figure 7, the engine 2 is driven and the first clutch 15 is engaged until time t1. At time t1, the motor mode implementation condition is met, causing the engine 2 to stop and the first clutch 15 to disengage. Subsequently, at time t3, the motor mode implementation condition is no longer met, while the engine mode implementation condition or the combined mode implementation condition is met, causing the engine 2 to resume operation and the first clutch 15 to resume engagement.

[0074] In the example in Figure 7, the catalyst temperature rises to above the predetermined temperature at time t6, which is after time t3. Consequently, the conditions for catalyst diagnosis are met from time t6 onward. Also, the engine water temperature rises to above the predetermined temperature at time t5, which is after time t3 but before time t6. Consequently, the conditions for front O2 diagnosis are met from time t5 onward. Furthermore, the voltage of the rear O2 sensor SN6 drops below the predetermined voltage at time t2, which is after time t1, but then begins to rise again, reaching above the predetermined voltage at time t4, which is before time t5. Therefore, the conditions for rear O2 diagnosis are met not only during the period up to time t2 but also from time t4 onward. Thus, in the example in Figure 7, all conditions for catalyst diagnosis, rear O2 diagnosis, and rear O2 diagnosis are met from time t6 onward.

[0075] Furthermore, in the example shown in Figure 7, all diagnostic conditions are met, and with pressure, engine 2 running, and the first clutch 15 engaged, the motor mode implementation condition is met at time t7. As a result, an engine drive continuation request is output at time t7. When an engine drive continuation request is output at time t7, the engine 2 continues to run and the first clutch 15 remains engaged even after time t7, despite the motor mode implementation condition being met.

[0076] In Figure 7, in the graphs showing the engine drive state, the state of the first clutch, and the output state of the engine drive continuation request, the dashed line illustrates the case where, after time t7, the diagnostic conditions are not met (fuel cut is not performed), and therefore the fault diagnosis is not performed. In this case, the engine 2 is driven and the first clutch 15 is engaged until time t9, which is the judgment time, and at time t9 the driving mode is switched to motor mode. As a result, at time t9 the engine 2 is stopped and the first clutch 15 is disengaged.

[0077] On the other hand, in the graphs of the engine drive state and the state of the first clutch in Figure 7, and the graph of the output state of the engine drive continuation request, the solid line illustrates the case where the diagnostic conditions are met after time t7 but before time t9 (fuel cut is performed) and the fault diagnosis is completed. In this case, at time t8, before time t9, the driving mode is switched to motor mode, the engine 2 is stopped, and the first clutch 15 is disengaged.

[0078] (effect, etc.) As described above, in the above embodiment, when the diagnostic conditions that enable fault diagnosis of the exhaust components provided in the exhaust passage 50, namely the front O2 sensor SN5, the rear O2 sensor SN6, and the purification device 52, are met while the engine is running, an engine drive continuation request is output. When an engine drive continuation request is output, even if the motor mode implementation conditions, which are the conditions for stopping the engine 2 and driving the motor 4, are met, the engine 2 is forcibly kept running. Therefore, the opportunities to perform fault diagnosis of the front O2 sensor SN5, the rear O2 sensor SN6, and the purification device 52 can be increased.

[0079] Furthermore, in the above embodiment, the determination time, which is the time during which the engine is forced to continue running, is set to be shorter when the battery SOC is large than when it is small. Therefore, when the vehicle occupants expect the engine 2 to stop and the motor 4 to run based on the large battery SOC, it is possible to prevent the engine 2 from continuing to run for a long period of time contrary to this expectation. And when the occupants are less likely to feel any discomfort about the engine 2 running because the battery SOC is small, the engine 2 will continue to run for a longer period of time. Therefore, while minimizing the discomfort caused to the occupants, it is possible to ensure sufficient engine 2 running time under the conditions for diagnosis, thereby increasing the opportunities for fault diagnosis of the front O2 sensor SN5, rear O2 sensor SN6, and purification device 52.

[0080] Furthermore, in the above embodiment, an engine drive continuation request is output and the engine 2 is forcibly driven only when all diagnostic conditions (front O2 diagnostic conditions, rear O2 diagnostic conditions, and catalyst diagnostic conditions) are met. Therefore, while ensuring opportunities for fault diagnosis of the front O2 sensor SN5, rear O2 sensor SN6, and purification device 52, the opportunities for the engine 2 to be forcibly driven, that is, the opportunities for the engine 2 to be driven under the conditions for motor mode implementation, can be minimized, thereby reducing discomfort to the occupants.

[0081] Furthermore, in the apparatus according to the above embodiment, once the fault diagnosis of the front O2 sensor SN5, the rear O2 sensor SN6, and the purification device 52 is completed, the request to continue engine operation is withdrawn, the engine 2 is stopped, and the motor 4 is started. Therefore, while ensuring an opportunity for fault diagnosis, it is possible to avoid unnecessarily prolonging the time during which the engine 2 is forced to continue operation, thereby further reducing the discomfort caused to the occupants.

[0082] (modified version) In the above embodiment, the case in which the exhaust components to be fault-diagnosed are the front O2 sensor SN5, the rear O2 sensor SN6, and the purification device 52 was described, but the specific types of exhaust components are not limited to these. Furthermore, the control according to the above embodiment may be applied to fault diagnosis of only some of these exhaust components.

[0083] Furthermore, in the above embodiment, we described a case in which an engine drive continuation request is output and the engine continues to run when all diagnostic conditions (front O2 diagnostic conditions, rear O2 diagnostic conditions, and catalyst diagnostic conditions) are met. However, the system may be configured so that an engine drive continuation request is output when one or more diagnostic conditions are met.

[0084] Furthermore, the specific details of the conditions for switching driving modes, the specific details of the diagnostic conditions and diagnostic execution conditions, and the specific details of determining whether or not there is a malfunction are not limited to those stated above. [Explanation of Symbols]

[0085] 2 engines 4 motors 14 batteries 50 Exhaust passage 52. Purification device (exhaust components) 100 controllers 110 Driving control unit 120 Fault Diagnosis Department SN5 Front O2 Sensor (Exhaust Part) SN6 Rear O2 Sensor (Exhaust Part) SN7 Battery Sensor (Remaining Capacity Detection Unit)

Claims

1. A vehicle fault diagnosis device comprising a motor as a driving source, an engine having an engine body with a combustion chamber formed therein and an exhaust passage connected thereto, and a battery that supplies power to the motor, A remaining capacity detection unit for detecting the remaining capacity of the aforementioned battery, A driving control unit that stops the engine and drives the motor when predetermined motor mode execution conditions are met, The system includes a fault diagnosis unit that determines whether or not an exhaust component provided in the exhaust passage is malfunctioning while the engine is running and while predetermined diagnostic conditions are met. The aforementioned fault diagnosis unit, If the motor mode implementation condition is met while the engine is running and the diagnostic conditions are met, the engine will continue to run for a predetermined period of time from the time the motor mode implementation condition is met until a predetermined period of time has elapsed. A vehicle fault diagnosis device characterized in that when the remaining capacity of the battery detected by the remaining capacity detection unit is large, the duration is set to be shorter than when it is small.

2. In the vehicle fault diagnosis device according to claim 1, Equipped with multiple exhaust components, The diagnostic conditions are set individually for each of the exhaust components. The fault diagnosis unit is characterized in that it performs the drive continuation control when the motor mode implementation condition is met while the engine is running and all of the diagnostic conditions are met, in a vehicle fault diagnosis device.

3. In the vehicle fault diagnosis device according to claim 2, The vehicle fault diagnosis device is characterized in that the exhaust component comprises a purification device provided in the exhaust passage for purifying exhaust gas, an upstream sensor provided upstream of the purification device for detecting the properties of exhaust gas, and a downstream sensor provided downstream of the purification device for detecting the properties of exhaust gas.

4. In a vehicle fault diagnosis device according to any one of claims 1 to 3, The vehicle fault diagnosis device is characterized in that, when the fault diagnosis unit completes the determination of whether or not the exhaust component is faulty while the drive continuation control is being performed, it stops the drive continuation control, stops the engine and drives the motor.

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