Exhaust gas purification device removal detection device

Abstract

To provide a removal determination device for an exhaust emission control device capable of improving the accuracy of determining whether the exhaust emission control device has been removed from an exhaust pipe.SOLUTION: A removal determination device for an exhaust emission control device performs removal determination processing of the exhaust emission control device on the basis of a change of a temperature of exhaust gas flowing into the exhaust emission control device provided in an exhaust passage of an engine and a change of a temperature of exhaust gas flowing out. A controller determines whether a first state where a difference between an actual measurement value and an estimation value of output of the engine is a predetermined value or larger is continued for a predetermined time or longer (Step S3), and prohibits execution of the removal determination processing when a determination that the output of the engine is in the first state is made (Yes in Step S3).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a device for determining whether an engine exhaust purification device has been removed from an exhaust pipe. [Background technology]

[0002] Patent Document 1 discloses a control device for an internal combustion engine that detects whether an exhaust aftertreatment device has been removed from an exhaust pipe. The device in Patent Document 1 includes a PM trapping device with a three-way catalyst as the exhaust aftertreatment device. The device determines whether the PM trapping device has been removed based on the temperature or exhaust pressure differential (before-after pressure differential) of exhaust gas flowing into or out of the PM trapping device. Specifically, the device in Patent Document 1 performs a first removal diagnosis to determine whether the PM repair device has been removed based on the difference between the time rate of change of a first exhaust gas temperature, which is the temperature of the exhaust gas flowing into the PM trapping device, and the time rate of change of a second exhaust gas temperature, which is the temperature of the exhaust gas flowing out of the PM trapping device. The device in Patent Document 1 performs the first removal diagnosis if the intake air flow rate or exhaust gas flow rate is less than a first predetermined flow rate. The device performs the second removal diagnosis to determine whether the PM repair device has been removed if the intake air flow rate or exhaust gas flow rate is equal to or greater than the first predetermined flow rate or a second predetermined flow rate greater than the first predetermined flow rate.

[0003] According to Patent Document 1, the greater the exhaust flow rate, the smaller the temperature change of the exhaust passing through the PM trapping device when heat is absorbed by or received from the PM trapping device, and the lower the accuracy of determining whether the PM trapping device is in a removed state through the first removal diagnosis. Therefore, the device of Patent Document 1 is configured to perform the first removal diagnosis under conditions in which exhaust gas from the internal combustion engine is increasing, as described above. Furthermore, the first removal diagnosis is configured to calculate a difference between the absolute value of the time rate of change of the first exhaust temperature and the absolute value of the time rate of change of the second exhaust temperature, and to determine that the PM trapping device is in a normal state (i.e., not removed) if the integrated value of this difference over a certain period of time is less than a predetermined threshold.

[0004] Patent Document 2 discloses a method and device for monitoring a particle filter in an exhaust gas passage of an internal combustion engine operated with gasoline. According to the description in Patent Document 2, when carbon particles deposited in the particle filter are burned, a predetermined change (difference) occurs in the temperature of the exhaust gas. Therefore, the device in Patent Document 2 is configured to monitor the temperature change before and after the particle filter by providing temperature sensors on both the inlet side and the outlet side of the particle filter. Patent Document 2 also describes that with such a configuration, if the above-mentioned predetermined change does not occur, it can be determined that the particle filter has been removed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-112039 [Patent Document 2] Patent No. 6283742 Summary of the Invention [Problem to be solved by the invention]

[0006] The device disclosed in Patent Document 1 utilizes the thermal capacity of the PM trap to detect removal of the PM trap based on an integrated value of the difference between the absolute values ​​of the temperature of the exhaust gas flowing into the PM trap and the temperature of the exhaust gas flowing out of the PM trap. However, the combustion state of an internal combustion engine may become unstable, for example, during startup. In such cases, the flow rate or temperature of the exhaust gas flowing into the PM trap may decrease compared to when the combustion state is stable. Therefore, when determining whether the PM trap or the particle filter has been removed based on the temperature difference between the exhaust gas upstream and downstream of the PM trap or the particle filter, as in the devices disclosed in Patent Document 1 and Patent Document 2, erroneous determination may occur.

[0007] Furthermore, the device disclosed in Patent Document 1 is configured to perform a first removal diagnosis when the intake air volume is less than a first predetermined flow rate. However, even if such a condition is met, if the combustion state of the internal combustion engine is unstable, the amount and temperature of gas actually emitted from the engine may change differently from when the combustion state is stable, which may lead to an erroneous determination. Therefore, the devices disclosed in Patent Document 1 or Patent Document 2 may not be able to correctly detect that the PM trapping device or particle filter has been unintentionally removed.

[0008] The present invention has been made with an eye on the above-mentioned technical problems, and aims to provide an exhaust purification device removal determination device that can improve the accuracy of determining whether an exhaust purification device has been removed from an exhaust pipe. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides an exhaust purification device removal determination device comprising an engine mounted on a vehicle and an exhaust purification device provided in the exhaust path of the engine for purifying the exhaust gas of the engine, and configured to perform a removal determination process for determining whether the exhaust purification device has been removed from the exhaust path based on changes in the temperature of the exhaust gas flowing into the exhaust purification device and changes in the temperature of the exhaust gas flowing out of the exhaust purification device, the device comprising a controller for controlling the engine, the controller determining that a first state is reached in which a state in which the difference between the actual measured value of the engine's output and an estimated value of the engine's output calculated based on parameters for controlling the engine is greater than or equal to a predetermined value continues for more than a predetermined time, and if the engine's output is in the first state, the controller prohibits execution of the removal determination process.

[0011] In addition, in the present invention, the controller may be configured to determine that a torque down has occurred due to an external factor including either a stoppage of fuel supply to the engine or a retard control of the ignition timing, and, if a torque down has occurred due to the external factor, prohibit execution of the removal determination process without determining that the engine is in the first state.

[0012] In addition, in the present invention, the controller may be configured to determine that, when the output of the engine is not in the first state, the actual measured value of the torque output by the engine is in a second state in which the actual measured value is equal to or greater than a predetermined torque threshold, and to execute the removal determination process when the torque of the engine is in the second state, and to prohibit execution of the removal determination process when the torque of the engine is not in the second state.

[0013] Furthermore, in the present invention, the vehicle further includes a motor as a driving force source, a power split mechanism having a plurality of rotating elements, in which the motor, the engine, and the drive wheels are each connected to a different rotating element among the plurality of rotating elements, and a resolver that detects the rotation speed of the motor, and the controller may be configured to calculate the actual measured value of a parameter related to the operating state of the engine based on the rotation speed of the motor detected by the motor resolver. [Effects of the Invention]

[0014] The removal determination device for an exhaust gas purification device of the present invention determines whether an exhaust gas purification device has been removed based on changes in the temperature of exhaust gas flowing into the exhaust gas purification device provided on an engine's exhaust path and changes in the temperature of exhaust gas flowing out of the exhaust gas purification device. When executing the removal determination process, the removal determination device compares the measured engine output with the estimated engine output. If the comparison results in a first state in which the difference between the measured engine output and the estimated engine output is equal to or greater than a predetermined value and continues for a predetermined period of time, the removal determination device prohibits execution of the removal determination process. If the engine output is in the first state, it is assumed that engine combustion is unstable. Because the removal determination process is executed based on the exhaust gas temperature, if the removal determination process is executed when engine combustion is unstable, there is a risk that an erroneous determination result will be detected. Therefore, if it is assumed that engine combustion is unstable, the removal determination device prohibits execution of the removal determination process, thereby preventing or suppressing such erroneous determination. Furthermore, since it is determined whether or not to perform the removal determination process based on the actual measured value of the engine output, it is possible to more reliably prevent erroneous determinations from occurring in the results of the removal determination process.

[0015] Furthermore, the removal determination device for an exhaust purification device of the present invention is configured to execute a removal determination process when the actual measured value of engine torque is equal to or greater than a predetermined torque threshold. Therefore, the removal determination device executes the removal determination process when it determines that the engine is outputting torque sufficient to generate the exhaust gas required for the removal determination process because the actual measured value of engine torque is equal to or greater than the torque threshold. In other words, the removal determination device prohibits execution of the removal determination process when it determines that the engine is outputting low torque. In other words, when the engine torque is low, the amount and temperature of exhaust gas may not be sufficient for the removal determination process, which could result in an erroneous determination. Therefore, execution of the removal determination process is prohibited when the actual measured value of engine torque is less than the torque threshold. This makes it possible to prevent or suppress such erroneous determinations from occurring in the removal determination process.

[0016] Furthermore, the removal determination device is only required to be able to execute the removal determination process even if engine combustion is unstable. Therefore, even if it is determined that engine combustion is unstable, the removal determination process is executed if the actual measured value of engine torque is equal to or greater than a predetermined torque threshold. That is, the removal determination device executes the removal determination process when it is determined that the actual measured value of engine torque is equal to or greater than the torque threshold, thereby determining that the engine is outputting torque sufficient to obtain the amount and temperature of exhaust gas required for the removal determination process. Therefore, it is possible to prevent a situation in which the execution of the removal determination process is prohibited even though it is possible to execute the removal determination process without erroneous determination. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic diagram illustrating an example of a vehicle equipped with an exhaust purification device according to an embodiment of the present invention. [Figure 2]FIG. 2 is a schematic diagram for explaining an exhaust system of an engine. [Figure 3] 4 is a flowchart illustrating an example of control executed by the removal determination device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of specific embodiments of the present invention and are not intended to limit the present invention.

[0019] The overall configuration of a vehicle to which an exhaust gas purification device removal determination device according to an embodiment of the present invention is applied is shown schematically in Fig. 1. The vehicle 1 shown in Fig. 1 is an example of a conventionally known hybrid vehicle, a so-called two-motor hybrid vehicle equipped with an engine 2 and two motors 3 and 4 as driving power sources. As shown in Fig. 1, the engine 2 and the first motor 3 are connected to each other via a power split mechanism 5, and the second motor 4 is connected to a power transmission path from the power split mechanism 5 to drive wheels 6.

[0020] The engine 2 shown in Fig. 1 is configured to generate power by burning a mixture of air and a fuel such as gasoline or diesel, similar to a conventional engine 2. As shown in Fig. 2, the engine 2 has a plurality of cylinders 7 for burning the mixture, and the plurality of cylinders 7 are formed in an engine block 8. Each cylinder 7 is provided with a spark plug 9 for igniting the mixture.

[0021] Each of the motors 3, 4 functions as a motor that outputs driving torque when power is applied, similar to motors used as driving force sources in conventional electric vehicles and hybrid vehicles. Each of the motors 3, 4 also functions as a generator that generates electric power when torque is applied and rotated. That is, each of the motors 3, 4 is a motor-generator. Specifically, each of the motors 3, 4 is configured as a permanent magnet synchronous motor, induction motor, or the like. Each of the motors 3, 4 is electrically connected to a battery (not shown) or the like, and is configured so that the electric power generated by the first motor 3 drives the second motor 4, and the torque output by the second motor 4 can be added to the driving force for propelling the vehicle 1.

[0022] The first motor 3 is provided with a resolver 10. The resolver 10 is a sensor that detects the rotation angle (number of rotations) of the first motor 3. The resolver 10 is a conventionally known sensor that is configured to detect the rotation angle by counting (accumulating) electrical signals generated by changes in reactance between a rotating rotor and a fixed stator.

[0023] The power split mechanism 5 is configured, for example, by a single-pinion planetary gear unit. Although not shown, the power split mechanism 5 is configured with a sun gear, a ring gear arranged concentrically with the sun gear, multiple pinion gears that mesh with the sun gear and the ring gear, and a carrier that holds each pinion gear so that it can revolve and rotate on its own axis. An input shaft to which torque is transmitted from the engine 2 is connected to the carrier, the sun gear is connected to the first motor 3, and the ring gear is connected to the drive wheels 6 and the second motor 4.

[0024] With this configuration, when the engine 2 outputs torque, the first motor 3 outputs a reaction torque, thereby transmitting the torque of the engine 2 to the drive wheels 6. For this reason, the drive device 11 of the vehicle 1 shown in FIG. 1 is configured to control the rotation speed of the engine 2 by the first motor 3. Specifically, a target output (power) of the engine 2 is calculated based on the required driving force and vehicle speed, and a target engine rotation speed is determined that will achieve that output with optimal fuel efficiency. The torque or rotation speed of the first motor 3 is controlled so that the engine rotation speed becomes the target engine rotation speed.

[0025] Furthermore, the vehicle 1 is configured to calculate the torque and output of the engine 2 based on the rotation angle of the first motor 3 detected by the resolver 10. For example, the torque of the engine 2 is calculated based on the actual measurement value of the rotation speed of the first motor 3 and the moment of inertia determined by the configuration of the drive device 11, such as the gear ratio of the power split mechanism 5. The output of the engine 2 is calculated based on the torque of the engine 2 calculated in this manner and the rotation speed of the engine 2 calculated by a crank angle sensor 12 that detects the angle of the crankshaft (not shown) of the engine 2. In this way, the actual measurement values ​​of the output and torque of the engine 2 are calculated, and their changes over time are obtained.

[0026] Next, the configuration of the exhaust path of the engine 2 will be described with reference to Fig. 2. Fig. 2 illustrates an exhaust gas purification device provided on the exhaust side of the engine 2, with reference numerals assigned only to parts necessary for the description. On the intake side of the engine 2, there are mainly provided an intake pipe 13, an intake manifold 14, a throttle valve 15, and a throttle opening sensor 16. On the exhaust side of the engine 2, there are mainly provided an exhaust manifold 17, an exhaust pipe 18, a catalytic device 19, and a PM trapping device 20.

[0027] The intake pipe 13 is a pipe for taking in outside air and is connected to the engine block 8 via an intake manifold 14. In addition to various components such as an air cleaner (not shown), the intake pipe 13 is provided with a throttle valve 15 for controlling the amount of air flowing through the intake pipe 13 based on the accelerator operation amount of the driver, etc. The intake pipe 13 is provided with a throttle opening sensor 16 for detecting the opening degree of the throttle valve 15.

[0028] The exhaust pipe 18 is a pipe for discharging exhaust gas generated by burning the air-fuel mixture in each cylinder 7 to the outside of the vehicle, and is connected to the engine block 8 via an exhaust manifold 17 .

[0029] This exhaust pipe 18 is provided with various devices for purifying unburned gases (carbon monoxide (CO) and hydrocarbons (HC)) and nitrogen oxides (NOx) contained in the exhaust and for capturing particulate matter. In the example shown in Fig. 1, the exhaust pipe 18 is provided with a catalytic device 19 such as an oxidation catalyst (two-way catalyst) or a three-way catalyst for purifying the unburned gases and NOx, and downstream of the catalytic device 19 is provided a PM trapping device 20 for capturing particulate matter.

[0030] The PM trapping device 20 shown in Fig. 2 is a device that purifies the exhaust gas of the engine 2, and is configured with a so-called wall-flow type filter. Specifically, the PM trapping device 20 is a filter called a GPF (Gasoline Particulate Filter) 21, and a three-way catalyst is supported on the filter. Therefore, unburned gas and NOx contained in the exhaust gas discharged from the catalytic device 19 can be effectively purified by the PM trapping device 20. In the following description, the filter will be simply referred to as the GPF 21.

[0031] The GPF 21 has an outer diameter that is approximately the same as the inner diameter of a casing formed by expanding the diameter of a portion of the exhaust pipe 18, and is assembled inside the casing 22. In other words, the casing 22 is provided in communication with the exhaust pipe 18, and is configured so that all of the exhaust gas that has flowed up to the casing 22 passes through the inside of the GPF 21.

[0032] An input temperature sensor 23 is provided in the exhaust pipe 18 between the catalytic converter 19 and the GPF 21 to detect the temperature of the exhaust gas flowing into the GPF 21. An output temperature sensor 24 is provided downstream of the GPF 21 to detect the temperature of the exhaust gas flowing out of the GPF 21.

[0033] The vehicle 1 is provided with an electronic control unit (hereinafter referred to as ECU) 25 that controls the engine 2 and the motors 3, 4 configured as described above. Like ECUs provided in conventional vehicles 1, this ECU 25 is mainly configured with a microcomputer and is configured to receive signals from various sensors provided in the vehicle 1, obtain results based on the input signals and pre-stored maps and arithmetic expressions, and output the results as control command signals to the engine 2 and the motors 3, 4. The signals input to the ECU 25 include the rotation speed of the first motor 3 detected by the resolver 10, and data related to temperatures measured by the input temperature sensor 23 and the output temperature sensor 24. The ECU 25 also includes an engine combustion determination unit 26, an engine torque determination unit 27, a temperature area calculation unit 28, and a GPF determination unit 29.

[0034] The engine combustion determination unit 26 determines whether the combustion of the engine 2 is stable. Specifically, the engine combustion determination unit 26 compares the actual measurement value of the output of the engine 2 calculated as described above with an estimated value of the output of the engine 2 obtained from the fuel injection amount and the intake air amount. If the difference between the actual measurement value and the estimated value of the output of the engine 2 continues to be equal to or greater than a predetermined value for a predetermined period of time or longer, the engine combustion determination unit 26 determines that the combustion of the engine 2 is unstable.

[0035] The engine torque determination unit 27 determines whether the actual measured value of the torque of the engine 2 is equal to or greater than a predetermined torque threshold. The torque threshold here is a value that determines whether the exhaust gas from the engine 2 is in a state that allows the removal determination process to be executed. In other words, the engine torque determination unit 27 determines whether the temperature, amount, etc. of the exhaust gas estimated from the actually measured torque of the engine 2 are sufficient to execute the removal determination process.

[0036] The temperature area calculation unit 28 calculates the integrated value of the temperature of the exhaust gas flowing into the GPF 21 and the integrated value of the temperature of the exhaust gas flowing out of the GPF 21. The temperature area calculation unit 28 acquires the time-dependent changes in each temperature detected by the input temperature sensor 23 and the output temperature sensor 24. The temperature area calculation unit 28 calculates the time required for the temperature of the exhaust gas flowing out of the GPF 21 to reach a predetermined temperature. The temperature area calculation unit 28 integrates the difference between the initial temperature of the input temperature sensor 23 and the changed temperature until the required time is reached, and also integrates the difference between the initial temperature of the output temperature sensor 24 and the changed temperature, and calculates the temperature area.

[0037] The GPF determination unit 29 determines whether the GPF 21 is removed based on the temperature area calculated by the temperature area calculation unit 28. The GPF determination unit 29 calculates the ratio of the temperature area based on the temperature of the exhaust gas flowing into the GPF 21 to the calculated temperature area based on the temperature of the exhaust gas flowing out of the GPF 21. If the calculated temperature area ratio is smaller than a predetermined area ratio, the GPF 21 is determined to be removed. Conversely, if the calculated temperature area ratio is equal to or greater than the predetermined area ratio, the GPF 21 is determined to be not removed. Because the GPF 21 has a relatively large heat capacity, if the GPF 21 is removed, the temperature of the output temperature sensor 24 begins to rise relatively quickly. The GPF determination unit 29 compares the temperature area ratio with the predetermined area ratio to detect a change and determine whether the GPF 21 is removed. The removal determination process is performed when the catalyst temperature is low.

[0038] Fig. 3 shows a flowchart for explaining an example of control executed by the ECU 25. In the flowchart shown in Fig. 3, when the vehicle 1 is capable of running, it is determined whether the PM trapping device 20, i.e., the GPF 21, provided on the exhaust path of the engine 2 has been removed, depending on the combustion state of the engine 2. In step S1, it is determined whether the preconditions for executing the removal determination process are met. In step S1, it is mainly determined whether the removal determination process needs to be executed, whether the removal determination process is possible, etc.

[0039] For example, it is determined that the removal determination process for the GPF 21 has been performed while the vehicle 1 is currently traveling. Note that "while traveling" refers to, for example, the period from when the ignition switch of the vehicle 1 is turned on until the present. If the removal determination has already been performed, it is determined that the precondition is not met, and a negative determination is made in step S1. It is also determined whether or not sensors required to calculate parameters used to perform the removal determination process are malfunctioning. For example, it is determined that the input temperature sensor 23, output temperature sensor 24, resolver 10, etc., described above, correctly detect each parameter. If these detectors cannot correctly detect the parameters, it is determined that the precondition is not met, and a negative determination is made in step S1. If a negative determination is made in step S1, the routine shown in this flowchart is temporarily terminated without executing the subsequent control.

[0040] Conversely, if a positive determination is made in step S1 because the preconditions are met, the process proceeds to step S2, where a torque reduction of the engine 2 is determined. In step S2, it is determined that the torque output by the engine 2 is reduced due to an external factor. Here, an external factor refers to a factor or event that changes the combustion state without the driver's operation, such as a fuel supply cutoff not initiated by the driver's accelerator pedal operation or ignition timing retardation control in a gasoline engine. When a torque reduction occurs due to such an external factor, the temperature and amount of exhaust gas necessary to execute the GPF removal determination process may become insufficient over time. In other words, an erroneous determination may occur when the GPF removal determination process is executed. To prevent such an erroneous determination, if a torque reduction occurs in the engine 2 due to an external factor, a YES determination is made in step S2, and the routine shown in this flowchart is temporarily terminated without executing the subsequent control.

[0041] If step S2 returns NO because no torque reduction due to an external factor has occurred in the engine 2, the process proceeds to step S3, where a determination is made as to whether or not there has been a reduction in the output of the engine 2. In step S3, it is determined whether or not the difference between the estimated value of the output of the engine 2 and the actual value of the output of the engine 2 is equal to or greater than a predetermined value, and whether or not this difference has remained equal to or greater than the predetermined value for a predetermined period of time. The estimated value of the output of the engine 2 can be estimated based on parameters for controlling the engine 2, the characteristics of the engine 2, and the like.

[0042] For example, when the driver depresses the accelerator pedal, a target engine torque (command torque) is determined according to the depression angle and pressure. The ECU 25 controls the fuel injection amount, intake air amount, ignition timing, and the like, so that the output torque of the engine 2 gradually increases up to the target engine torque. At this time, the torque output by the engine 2 can be estimated based on the control parameters of the engine 2, such as the fuel injection amount, intake air amount, and ignition timing, which are controlled by the ECU 25, as well as the characteristics of the engine 2. An estimated value of the output of the engine 2 can be calculated by multiplying the estimated torque of the engine 2 by the rotation speed of the engine 2 detected by the crank angle sensor 12 of the engine 2.

[0043] Furthermore, the actual measured value of the output of the engine 2 is calculated using the detection result of the resolver 10, as described above. Specifically, the actual measured output of the engine 2 can be calculated by first determining the angular acceleration of the motor from the angular velocity of the motor detected by the resolver 10, and then multiplying the calculated angular acceleration by the moment of inertia determined by the configuration (specifications) of the drive device 11, such as the shaft and gears. The actual measured output of the engine 2 can be calculated by multiplying the calculated actual engine torque by the rotation speed of the engine 2 determined from the value detected by the crank angle sensor 12 of the engine 2.

[0044] The predetermined value and predetermined time in step S3 may be set to include a margin of error determined by, for example, environmental influences such as temperature, the characteristics of the engine 2, the configuration of the drive unit 11, and the like. In other words, the predetermined value and predetermined time may be any value that can determine whether combustion in the engine 2 is stable, and may be determined in advance based on the results of experiments, simulations, or the like. If the difference between the estimated output and the measured output of the engine 2 remains greater than or equal to the predetermined value for a predetermined period of time or longer, step S3 returns to YES, and the routine illustrated in this flowchart is temporarily terminated without executing any subsequent control. Note that the output of the engine 2 may temporarily change due to various factors, such as at startup. Therefore, step S3 is configured to determine that there is no abnormality in the output of the engine 2 if the difference is greater than or equal to the predetermined value but the predetermined period of time has not yet elapsed. Furthermore, the fact that the difference between the estimated output and the measured output of the engine 2 remains greater than or equal to the predetermined value for a predetermined period of time or longer corresponds to the output of the engine 2 being in the first state in this embodiment of the present invention.

[0045] On the other hand, if step S3 returns NO because there is no abnormality in the output of engine 2 and the process proceeds to step S4, it is determined that the actual measured value of the output torque of engine 2 is equal to or greater than the torque threshold. In step S4, it is determined that the torque required to execute the removal determination process for GPF 21 is being output from engine 2. That is, in step S4, it is determined whether engine 2 is outputting a torque that does not reduce the accuracy of the removal determination process, for example, when the combustion state of engine 2 is stable in step S3 but the temperature of exhaust gas is high or a sufficient amount of exhaust gas is obtained. For this reason, the torque threshold is set to a lower limit of the engine torque required to execute the removal determination process, and is set to, for example, a torque slightly greater than the torque required for engine 2 to rotate autonomously.

[0046] If the actual measured value of the torque of the engine 2 calculated as described above is smaller than the torque threshold value and therefore the determination in step S4 is NO, the routine shown in this flowchart is temporarily terminated without executing the subsequent control. That is, even if the combustion of the engine 2 is stable, the output torque of the engine 2 is small, and therefore it may be impossible to make an accurate determination even if the removal determination process described above is executed. Therefore, execution of the removal determination process at this time is prohibited. Note that the actual measured value of the torque of the engine 2 being equal to or greater than the predetermined torque threshold value corresponds to the torque of the engine 2 being in the second state in this embodiment of the present invention.

[0047] If the determination in step S4 is YES because the actual measured torque of the engine 2 is equal to or greater than the torque threshold value, the process proceeds to step S5, where a process for determining whether to remove the GPF 21 is executed. The process for determining whether to remove the GPF 21 is a conventionally known process, and is executed by comparing the integrated values ​​of the temperature of the exhaust gas flowing into the GPF 21 and the temperature of the exhaust gas flowing out of the GPF 21.

[0048] In step S5, the time it takes for the temperature of the exhaust gas flowing out of the GPF 21, detected by the output temperature sensor 24, to reach a predetermined temperature after the start of the engine 2 is detected. The temperature changes of the exhaust gas flowing into the GPF 21 and the exhaust gas flowing out of the GPF 21, detected by the input temperature sensor 23 and the output temperature sensor 24, during the required time from the start of the engine 2 until the detected reaching time are detected. The temperature changes here refer to the difference from the initial temperatures of each temperature sensor. Based on the detected temperature changes over time, an integrated value of the temperature changes of each exhaust gas up to the required time is calculated, and the temperature areas of the exhaust gas flowing into the GPF 21 and the exhaust gas flowing out of the GPF 21 are calculated. Then, in step S5, the ratio of the temperature area of ​​the exhaust gas flowing into the GPF 21 to the temperature area of ​​the exhaust gas flowing out of the GPF 21 is calculated, and the process proceeds to step S6.

[0049] In step S6, it is determined whether the temperature area ratio calculated in step S5 is smaller than a predetermined area ratio. The temperature of the exhaust gas flowing out of the GPF 21 drops by an amount corresponding to the heat capacity of the GPF 21. Therefore, the temperature area ratio changes depending on whether the GPF 21 is installed or removed, depending on the heat capacity of the GPF 21. For example, when the GPF 21 is removed, the temperature of the exhaust gas flowing out of the GPF 21 begins to rise earlier than when the GPF 21 is installed. On the other hand, the temperature of the exhaust gas flowing into the GPF 21 is less affected by the removal of the GPF 21. Furthermore, because the temperature of the exhaust gas flowing into the GPF 21 rises first, the temperature area based on the temperature of the exhaust gas flowing into the GPF 21 decreases more than the temperature area based on the temperature of the exhaust gas flowing out of the GPF 21. Therefore, when the above-mentioned temperature area ratio is calculated, the temperature area ratio when the GPF 21 is removed is smaller than the temperature area ratio when the GPF 21 is installed. Such a difference in the temperature-area ratio is noticeable because the heat capacity of the GPF 21 is relatively large. Therefore, the predetermined area ratio is set in advance based on the results of experiments, simulations, etc., to a ratio that allows the difference in the temperature-area ratio to be detected.

[0050] If the calculated temperature area ratio is smaller than the predetermined area ratio and therefore the determination in step S6 is YES, the process proceeds to step S7, where it is determined that the GPF 21 has been removed. If the process proceeds to step S7, the temperature area ratio is smaller than the predetermined area ratio, which means that the temperature of the exhaust gas flowing out of the GPF 21 has started to rise early. Therefore, it is determined that the GPF 21 has been removed, and the routine shown in this flowchart is temporarily terminated.

[0051] Conversely, if the temperature area ratio is equal to or greater than the predetermined area ratio and therefore the determination in step S6 is NO, the process proceeds to step S8, where it is determined that the GPF 21 has not been removed. If the process proceeds to step S8, since the temperature area ratio is equal to or greater than the predetermined area ratio, it is assumed that the temperature rise of the exhaust gas flowing out of the GPF 21 has started with a delay corresponding to the heat capacity of the GPF 21, so it is determined that the GPF 21 has not been removed, and the routine shown in this flowchart is temporarily terminated.

[0052] The removal determination device for the GPF (exhaust gas purification device) 21 according to the embodiment of the present invention determines whether combustion in the engine 2 is stable based on the estimated output of the engine 2 and the actually measured output of the engine 2. If it is determined based on this determination that combustion in the engine 2 is stable, the device is configured to execute a removal determination process for the GPF 21.

[0053] The removal determination process for the GPF 21 is performed based on the temperature of the exhaust gas flowing into the GPF 21 and the temperature of the exhaust gas flowing out of the GPF 21. Therefore, when combustion in the engine 2 is unstable, for example, the temperature of the exhaust gas detected by the input temperature sensor 23 may be low due to a small amount of exhaust gas, or the temperature of the exhaust gas flowing out of the GPF 21 may be high due to the influence of components contained in the exhaust gas. In such cases, the temperature area ratio obtained based on each exhaust gas may be affected, which may result in an erroneous determination in the removal determination process. In the above-described embodiment, when unstable combustion in the engine 2 is detected, the execution of the removal determination process is prohibited, thereby preventing or suppressing such an erroneous determination. Furthermore, because whether or not to perform the removal determination process is determined based on actual measured values ​​of the output and torque of the engine 2, it is possible to more reliably suppress an erroneous determination as a result of the removal determination process.

[0054] Furthermore, the removal determination device according to the embodiment of the present invention is configured to execute the removal determination process when the output torque of the engine 2 is equal to or greater than the torque threshold. Therefore, the removal determination device executes the removal determination process when it determines that the engine 2 is outputting torque large enough to generate the exhaust gas required for the removal determination process because the actual measured torque of the engine 2 is equal to or greater than the torque threshold. In other words, even if the combustion state of the engine 2 is stable, if the removal determination device determines that the torque output by the engine 2 is small, the amount and temperature of exhaust gas may not be sufficient for the removal determination process, and therefore the removal determination device prohibits the execution of the removal determination process. Therefore, it is possible to prevent or suppress erroneous removal determinations.

[0055] Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples and may be modified as appropriate within the scope of achieving the object of the present invention. For example, in the above-described flowchart, whether to execute the removal determination process may be determined solely by determining whether the actual measured value of engine torque is equal to or greater than the torque threshold value. That is, the removal determination process may be determined based on only one of the determinations in step S3 or step S4. Furthermore, the determination may be based on other parameters, not just the output of the engine 2, as long as it is possible to determine that the combustion in the engine 2 is stable. For example, the removal determination device may be configured to determine the combustion state of the engine 2 based on the torque of the engine 2, instead of determining the combustion state based on the output of the engine 2.

[0056] In this case, similar to the process in step S3, the difference between the estimated value of the torque of the engine 2 and the actual measured value of the torque of the engine 2 is compared, and it is determined whether the difference has remained greater than or equal to a predetermined torque difference for a predetermined period of time or longer. The predetermined torque difference and the predetermined period of time may be set within an error range determined, for example, by environmental influences such as temperature, the characteristics of the engine 2, the configuration of the drive unit 11, and the like. In other words, any value that can determine whether combustion in the engine 2 is unstable may be used, and may be determined in advance based on the results of experiments, simulations, or the like. If the difference between the estimated value of the torque of the engine 2 and the actual measured value of the engine torque has remained greater than or equal to the torque difference for a predetermined period of time or longer, a YES determination is made, and execution of the removal determination process is prohibited or the process proceeds to step S4 described above. Conversely, if the torque of the engine 2 is not in such a state, a NO determination is made, and the removal determination process is executed or the process proceeds to step S5 described above. The process of determining the combustion state of the engine 2 based on the torque of the engine 2 may be configured to be executed before the process of step S3 is executed or after the process of step S3 is executed.

[0057] Furthermore, the removal determination device may be configured to execute the process of step S4 when the determination in step S3 is YES. That is, when the determination in step S3 is YES due to an abnormality in the output of engine 2, the removal determination device may be configured to execute step S4, in which it is determined that the actual measured value of the output torque of engine 2 is equal to or greater than the torque threshold. In this case, if the actual measured value of the torque of engine 2 is smaller than the torque threshold, the determination in step S4 may be NO, and the routine shown in the flowchart may be temporarily terminated without executing the removal determination process. That is, because the combustion of engine 2 has become unstable and the output torque of engine 2 is small, even if the above-mentioned removal determination process is executed, an accurate determination may not be possible, and therefore execution of the removal determination process at this time is prohibited. Conversely, if the actual measured value of the torque of engine 2 is abnormal relative to the torque threshold, the determination in step S4 may be YES, the process may proceed to step S5, and the removal determination process may be executed.

[0058] That is, it is sufficient if the removal determination process can be executed even if the combustion of the engine 2 is unstable. Therefore, in step S4 of this configuration, even if the combustion state of the engine 2 has deteriorated in steps S2 and S3, it is determined whether the engine 2 is outputting torque to the extent that the accuracy of the removal determination process does not decrease, for example, because the exhaust gas temperature is high or a sufficient amount of exhaust gas is being obtained. Therefore, if it is determined that the engine 2 is outputting torque of a magnitude that can generate the exhaust gas necessary for the removal determination process because the actual engine torque of the engine 2 is equal to or greater than the torque threshold, the removal determination process is executed. This makes it possible to prevent or suppress a situation in which the execution of the removal determination process is prohibited even when the result of the removal determination process can be correctly determined. [Explanation of symbols]

[0059] 2 engines 3 First motor 5 Power split mechanism 6 drive wheels 10 Resolver 19 Catalytic converter 20 PM collection device 21 Exhaust gas purification device (GPF) 25 Controller (ECU) 26 Engine combustion determination unit 27 Engine torque determination unit 28 Temperature area calculation section 29 GPF judgment unit

Claims

1. An exhaust gas purification device removal determination device is provided in an exhaust path of the engine, the exhaust gas purification device being configured to perform a removal determination process to determine whether or not the exhaust gas purification device has been removed from the exhaust path, based on a change in temperature of the exhaust gas flowing into the exhaust gas purification device and a change in temperature of the exhaust gas flowing out of the exhaust gas purification device, a controller for controlling the engine; The controller determining that a state in which a difference between an actual measurement value of the engine output and an estimated value of the engine output calculated based on parameters for controlling the engine is equal to or greater than a predetermined value continues for equal to or greater than a predetermined time period, and When the output of the engine is in the first state, execution of the removal determination process is prohibited. A device for determining whether an exhaust gas purification device has been removed.

2. A device for determining whether an exhaust purification device described in claim 1 is removed, The controller determining that a torque reduction has occurred in the engine due to an external factor including either a fuel supply cutoff or ignition timing retard control; When a torque down due to the external factor occurs, the execution of the removal determination process is prohibited without determining whether the engine is in the first state. A device for determining whether an exhaust gas purification device has been removed.

3. The exhaust gas purification device removal determination device according to claim 1 or 2, The controller When the output of the engine is not in the first state, it is determined that the output of the engine is in a second state in which an actual measured value of the torque output by the engine is equal to or greater than a predetermined torque threshold value; When the torque of the engine is in the second state, the removal determination process is executed; When the torque of the engine is not in the second state, execution of the removal determination process is prohibited. A device for determining whether an exhaust gas purification device has been removed.

4. The exhaust gas purification device removal determination device according to claim 1 or 2, The vehicle is a motor as a driving force source; a power split mechanism having a plurality of rotating elements, the motor, the engine, and the drive wheels being respectively coupled to different rotating elements of the plurality of rotating elements; A resolver that detects the rotation speed of the motor, The controller The actual measured value of a parameter relating to the operating state of the engine is calculated based on the rotation speed of the motor detected by the resolver. A device for determining whether an exhaust gas purification device has been removed.

Images