JP2019214952A - Filer removal detection device - Google Patents

Abstract

To provide a filter removal detection device which can detect that a particulate substance removal filter is removed with simple constitution.SOLUTION: A filter removal detection device comprises: a first temperature acquisition device for acquiring a first temperature of a particulate substance removal filter for collecting particulate substances at an upstream side at each prescribed time, and storing it in time series; a second temperature detection device for detecting a second temperature of the particulate substance removal filter at a downstream side at each prescribed time; a downstream-side temperature estimation device for calculating an estimation temperature of the particulate substance removal filter at the downstream side when the particulate substance removal filter is attached on the basis of the first temperature acquired by the first temperature acquisition device; and a filter determination device for determining whether or not the particulate substance removal filter is removed on the basis of the estimation temperature calculated by the downstream-side temperature estimation device, and the second temperature detected by the second temperature detection device.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a filter removal detection device that detects removal of a particulate matter removal filter that removes particulate matter discharged from an internal combustion engine.

  An exhaust gas purifying device for a diesel engine is a particulate matter removal filter (usually called a Diesel Particulate Filter, which collects and removes particulate matter (PM) in exhaust gas, and is hereinafter referred to as "DPF". )). Here, since the DPF for purifying the exhaust gas collects particulate matter in the exhaust gas, from the viewpoint of environmental protection, when the vehicle is driven with the DPF removed, the DPF is removed. It is desired to detect that it is being performed. Therefore, various techniques for detecting that the DPF has been removed have been proposed.

  For example, in a device for monitoring a particle filter described in Patent Literature 1 below, a three-way catalyst is arranged after an internal combustion engine in an exhaust gas passage, and a particle filter is arranged behind the three-way catalyst. . The temperature of the exhaust gas is determined by a first temperature sensor located before the particle filter and a second temperature sensor located after the particle filter. The first temperature sensor and the second temperature sensor are connected to a control unit, in which the signal of each temperature sensor is evaluated, from which the presence of a particle filter is monitored.

  Specifically, the temperature before the particle filter after the cold start of the internal combustion engine rises with the start of the internal combustion engine, and is adjusted to the operating temperature after passing the maximum value. The temperature after the particle filter has a smaller amplitude of temperature fluctuation than the temperature change before the particle filter, with a delay (dead time) defined by the heat capacity of the particle filter. On the other hand, when the particle filter is removed from the exhaust gas passage, this delay time is eliminated, and the temperature after the particle filter rises to reach the operating temperature with a slight delay. Thus, when the temperature rise after the particle filter is smaller than the temperature change before the particle filter, with a defined delay, relative to the temperature rise before the particle filter, The control unit is configured to assume that the particle filter is correctly installed.

JP 2006-535831 A

  However, in the apparatus for monitoring a particle filter described in Patent Document 1, it is necessary to detect a delay time of a temperature rise after the particle filter with respect to a temperature rise before the particle filter during transient operation of the internal combustion engine. There is. For this reason, when the temperature before and after the particle filter is detected at a constant period (for example, every one second, etc.), the transient operation time is short, and the transient operation is passed. Sometimes the temperature before and after the particle filter is measured, and the measurement error may increase.

  Further, it is necessary to measure the amplitude of the temperature fluctuation before and after the particle filter. However, if the measurement interval (for example, 1 second interval) is large, there is a possibility that the measurement error of the maximum value of the amplitude becomes large. . Further, after detecting the temperature before the particle filter, it is necessary to detect the temperature after the particle filter until a time delayed by a predetermined time, and to compare the temperature before and after the temperature. For this reason, when the measurement interval is large (for example, at one-second intervals), the temperature measurement error after the particle filter becomes large, that is, there is a possibility that the temperature measurement after the particle filter may be omitted. As a result, there is a possibility that the particle filter is erroneously determined to be incorporated even though the particle filter is not incorporated.

  Therefore, the present invention has been made in view of such a point, and an object of the present invention is to provide a filter removal detection device which can detect removal of a particulate matter removal filter with a simple configuration. And

  In order to solve the above-mentioned problems, a first invention of the present invention provides a method in which a first temperature on an upstream side of a particulate matter removal filter which is disposed in an exhaust gas passage of an internal combustion engine and collects particulate matter is increased every predetermined time. A first temperature acquisition device that acquires and stores in chronological order, a second temperature detection device that detects a second temperature downstream of the particulate matter removal filter at every predetermined time, and the first temperature acquisition device A downstream temperature estimating device that calculates an estimated temperature downstream of the particulate matter removal filter when the particulate matter removal filter is mounted, based on the first temperature obtained by A filter determining device that determines whether the particulate matter removal filter has been removed based on the estimated temperature calculated by the temperature estimating device and the second temperature detected by the second temperature detecting device. , Equipped with a filter removal detection device.

  Next, according to a second invention of the present invention, in the filter removal detection device according to the first invention, the downstream temperature estimating device includes the first temperature stored before a predetermined dead time and the waste temperature. A filter removal detection device, comprising: a calculation unit that calculates the estimated temperature based on the first temperature, the first-order lag coefficient, and the heat removal coefficient of the particulate matter removal filter stored one immediately before time. .

  Next, according to a third invention of the present invention, in the filter removal detection device according to the first invention or the second invention, a water temperature detection device for detecting a temperature of cooling water for cooling the internal combustion engine; A water temperature determining device that determines whether or not the water temperature detected by the detecting device is equal to or higher than a predetermined temperature, wherein the downstream temperature estimating device is configured such that the water temperature is equal to or higher than the predetermined temperature by the water temperature determining device. A filter removal detection device that performs the calculation of the estimated temperature when the determination is made.

  Next, a fourth invention of the present invention is the filter removal detection device according to any one of the first invention to the third invention, wherein the filter determination device is configured to determine the estimated temperature and the second temperature. An absolute value of the temperature difference of the, having a counting unit that counts the cumulative number of times has become equal to or more than a predetermined error threshold, when the cumulative number counted by the counting unit reaches a predetermined number, the particulate matter A filter removal detection device that determines that a removal filter has been removed.

  According to the first aspect, the estimated temperature on the downstream side of the DPF is determined based on the first temperature on the upstream side of the particulate matter removal filter (hereinafter, referred to as “DPF”) acquired by the first temperature acquisition device. calculate. Then, it is determined whether or not the DPF has been removed based on the estimated temperature and the second temperature downstream of the DPF detected by the second temperature detection device.

  This makes it possible to detect that the DPF has been removed with a simple configuration in which the first temperature acquisition device and the second temperature detection device are arranged upstream and downstream of the DPF. Further, each time the second temperature detecting device detects the second temperature downstream of the DPF, it is possible to determine whether or not the DPF has been removed based on the second temperature and the estimated temperature. In addition, even if the measurement interval of the second temperature increases, it is possible to suppress erroneous determination.

  According to the second aspect, the rise of the second temperature on the downstream side of the DPF has a predetermined time delay (dead time) with respect to the rise of the first temperature on the upstream side of the DPF. Therefore, the dead time of the DPF, the first-order lag coefficient, and the radiation coefficient of the particulate matter removal filter are obtained in advance by actual measurement or CAE (Computer Aided Engineering) analysis, and are stored before the predetermined dead time. The first temperature on the upstream side of the DPF, the first temperature on the upstream side of the DPF stored one immediately before this dead time, the first-order lag coefficient, and the heat removal coefficient of the particulate matter removal filter, It is possible to calculate the estimated temperature downstream of the DPF.

  Accordingly, each time the second temperature on the downstream side of the DPF is detected, it is possible to determine whether or not the DPF has been removed based on the calculated estimated temperature and the second temperature. Can be quickly detected.

  According to the third aspect, when it is determined that the temperature of the cooling water for cooling the internal combustion engine is equal to or higher than the predetermined temperature, the estimated temperature is calculated, so that the accuracy of the estimated temperature can be improved. It is possible to determine with high accuracy that the DPF has been removed.

  According to the fourth aspect, when the cumulative number of times that the absolute value of the temperature difference (error) between the estimated temperature and the second temperature on the downstream side of the DPF becomes equal to or more than the predetermined error threshold reaches the predetermined number, Since it is determined that the DPF has been removed, the erroneous determination can be appropriately suppressed by setting the predetermined number of times to an appropriate number.

It is a figure showing the internal-combustion engine to which the filter removal detection device concerning this embodiment was applied. It is a flowchart which shows the filter removal detection process which detects removal of DPF. It is a figure which shows an example of each temperature change of the upstream and downstream of the DPF when the DPF is mounted, and the estimated temperature of the downstream. It is a figure which shows an example of each temperature of the upstream and downstream at the position where a DPF is mounted when the DPF is removed, and the estimated temperature of the downstream. It is a figure which shows an example of the change of the absolute value of the error of the measured temperature with respect to the estimated temperature of the downstream of the DPF when the DPF is mounted and when it is removed.

  Hereinafter, a filter removal detection device according to an embodiment of the present invention will be described in detail with reference to the drawings based on an embodiment. FIG. 1 shows an example of a configuration of an internal combustion engine 10 to which a filter removal detection device according to the present invention is applied. The internal combustion engine 10 is a diesel engine. In the following description, the DPF 43 corresponds to a particulate matter removal filter (Diesel Particulate Filter). Further, a description of a selective reduction catalyst or the like which is disposed in an exhaust passage downstream of the DPF 43 and renders nitrogen oxides (NOx) harmless is omitted.

  As shown in FIG. 1, an exhaust gas purification device 41 is provided in an exhaust passage (exhaust gas passage) 12 of the internal combustion engine 10. An oxidation catalyst (DOC: Diesel Oxidation Catalyst) 42 and a DPF 43 are provided inside the exhaust gas purification device 41 from the upstream side. The exhaust gas purification device 41 forms an exhaust gas passage, and removes harmful substances contained in the exhaust gas while the exhaust gas passes from the upstream side to the downstream side. Here, the internal combustion engine 10 has high efficiency and excellent durability, but is harmful such as particulate matter (PM), nitrogen oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC). Is discharged together with the exhaust gas.

  The oxidation catalyst 42 is formed of a ceramic cylindrical body formed in a cylindrical shape or the like. A large number of through holes are formed in the axial direction, and the inner surface is coated with a noble metal such as platinum (Pt). Then, the oxidation catalyst 42 passes nitrogen oxide (NOx), carbon monoxide (CO), hydrocarbon (HC), and the like contained in the exhaust gas by passing the exhaust gas through a large number of through holes at a predetermined temperature. Oxidized and removed.

  The DPF 43 is formed in a columnar shape or the like by a porous member made of a ceramic material or the like, and forms a honeycomb-shaped cell-shaped cylindrical body provided with a large number of small holes in an axial direction. The other end is closed by a plugging member. Then, the DPF 43 captures particulate matter (PM) by passing the exhaust gas flowing into each small hole from the upstream side through the porous material, and causes only the exhaust gas to flow downstream through the adjacent small hole. .

  On the upstream side of the oxidation catalyst 42 (upstream of the exhaust gas purifying device 41), the fuel addition valve 28 and the exhaust gas temperature detecting device 36A (for example, an exhaust gas temperature sensor) are provided. The fuel addition valve 28 injects fuel to react with the exhaust gas in the oxidation catalyst 42 to increase the temperature of the exhaust gas when regenerating the DPF 43 on which the fine particles are deposited (when burning and burning particulate matter). I do. An exhaust temperature detection device 36B (for example, an exhaust temperature sensor) (first temperature acquisition device) is provided downstream of the oxidation catalyst 42 and upstream of the DPF 43. Note that the exhaust gas temperature detection device 36B may be disposed at the front end of the DPF 43 in the flow direction of the exhaust gas.

  An exhaust temperature detecting device 36C (for example, an exhaust temperature sensor) (a second temperature detecting device) is provided downstream of the DPF 43. Note that the exhaust gas temperature detection device 36C may be disposed at the rear end of the DPF 43 in the flow direction of the exhaust gas. Further, in the exhaust gas purifying device 41, a differential pressure (pressure) between an exhaust pressure (corresponding to an exhaust pipe pressure) downstream of the oxidation catalyst 42 and upstream of the DPF 43 and an exhaust pipe pressure downstream of the DPF 43. A differential pressure detecting device 35 (for example, a differential pressure sensor) for detecting the differential pressure) is provided.

  The fuel addition valve 28 is driven by a control signal from a control device (ECU: Electronic Control Unit) 50. The control device 50 is a known device including a CPU, a RAM, a ROM, a timer, a backup RAM (not shown), and the like. The CPU executes various arithmetic processes based on various programs and maps stored in the ROM. Further, the RAM temporarily stores the result of calculation by the CPU, data input from each detection device, and the like, and the backup RAM stores, for example, data to be stored when the internal combustion engine 10 is stopped.

  Further, the exhaust gas temperature detection device 36A outputs a detection signal corresponding to the temperature of the exhaust gas in the exhaust pipe on the upstream side of the oxidation catalyst 42 to the control device 50. Further, the exhaust gas temperature detection device 36B outputs a detection signal corresponding to the temperature of the exhaust gas flowing downstream of the oxidation catalyst 42 and upstream of the DPF 43 to the control device 50. Further, the exhaust gas temperature detection device 36C outputs a detection signal corresponding to the temperature of the exhaust gas on the downstream side of the DPF 43 to the control device 50. The differential pressure detecting device 35 is a detection signal corresponding to a differential pressure between the exhaust pressure downstream of the oxidation catalyst 42 and upstream of the DPF 43 (corresponding to the exhaust pipe internal pressure), and the exhaust pipe internal pressure downstream of the DPF 43. Is output to the control device 50.

  The control device 50 includes a detection signal of an intake air flow detection device 31 (for example, an air flow meter) provided in the intake passage 11, a detection signal of a water temperature detection device 32 (for example, a water temperature sensor), and a detection signal of an accelerator opening detection device 33. Each of the detection signal and the detection signal of the rotation detection device 34 is input. Further, the detection signal of the outside temperature sensor 18 for detecting the outside temperature of the vehicle is input to the control device 50.

  Further, the detection signal of each of the above-described exhaust gas temperature detection devices 36A, 36B, 36C and the detection signal of the differential pressure detection device 35 are input to the control device 50. Then, the control device 50 can detect the operating state of the internal combustion engine 10 based on the detection signals from these detection devices. The control device 50 also controls the operation of the internal combustion engine 10 from each of the injectors 14A to 14D based on the detected operating state of the internal combustion engine 10 and a request from the driver based on the detection signal from the accelerator opening detection device 33. And a control signal for controlling the amount of fuel injected into the fuel injection valve and the amount of fuel injected from the fuel addition valve 28.

  The fuel injected into the exhaust gas from the fuel addition valve 28 undergoes an oxidation reaction with oxygen remaining in the exhaust gas by the oxidation catalyst 42 and burns, and the temperature of the exhaust gas rises due to the heat generated. When the bed temperature of the DPF 43 rises due to the high-temperature exhaust gas and reaches a predetermined temperature or higher (for example, 590 ° C. or higher), particulate matter (PM) deposited in the DPF 43 is burned and incinerated. By maintaining such a state for a predetermined time, the particulate matter deposited in the DPF 43 is burned and removed, and the collecting function of the DPF 43 for collecting the particulate matter (PM) in the exhaust gas is restored. (Play).

  The intake air flow rate detection device 31 (for example, an intake flow rate sensor) is provided in the intake passage 11 of the internal combustion engine 10 and outputs a detection signal to the control device 50 in accordance with the flow rate of the air taken in by the internal combustion engine 10. The water temperature detection device 32 (for example, a water temperature sensor) outputs a detection signal corresponding to the temperature of the cooling water of the internal combustion engine 10 to the control device 50, for example. The accelerator opening detection device 33 (for example, an accelerator opening sensor) outputs a detection signal to the control device 50 according to the opening of the accelerator operated by the driver (that is, the load required by the driver). The rotation detection device 34 (for example, a rotation sensor) outputs a detection signal corresponding to the rotation speed of the crankshaft of the internal combustion engine 10 (that is, the engine rotation speed) to the control device 50, for example.

  Further, in the example shown in FIG. 1, the control device 50 can turn on / off the filter warning lamp 15 which is turned on when detecting that the DPF 43 has been removed, as described later. The filter warning lamp 15 is provided, for example, in an instrument panel of the vehicle. Further, the control device 50 is connected to a connector 16 for connecting a separate vehicle diagnostic tool 61. When the vehicle diagnostic tool 61 is connected to the connector 16, the control device 50 and the vehicle diagnostic tool 61 can transmit and receive various information and commands.

  Next, an example of a filter removal detection process for detecting removal of the DPF 43 by the control device 50 in the internal combustion engine 10 configured as described above will be described with reference to FIGS. The control device 50 repeatedly executes the control process shown in the flowchart of FIG. 2 at predetermined time intervals (for example, at intervals of several hundred msec to about 1 second) while the internal combustion engine 10 is operating. The program shown in the flowchart in FIG. 2 is stored in the ROM of the control device 50 in advance.

  As shown in FIG. 2, first, in step S11, the control device 50 controls the exhaust gas temperature T1 (first temperature) of the exhaust gas on the upstream side of the DPF 43 and the exhaust gas on the downstream side of the DPF 43 by the exhaust gas temperature detecting devices 36B and 36C. The temperature T2 (second temperature) of the gas is measured, and the temperatures T1 and T2 are stored in the RAM in time series. The control device 50 stores only the temperature T1 of the exhaust gas upstream of the DPF 43 in the RAM in a time-series manner, and stores only the current measurement value of the temperature T2 of the exhaust gas downstream of the DPF 43 in the RAM. You may do so.

  Subsequently, in step S12, control device 50 determines whether or not a preset precondition is satisfied. This precondition is an execution condition for executing the processing after step S13 for determining whether or not the DPF 43 has been removed. For example, the precondition includes a condition that the temperature of the cooling water of the internal combustion engine 10 input from the water temperature detecting device 32 is equal to or higher than a predetermined temperature (for example, approximately 70 ° C. or higher).

  Further, the precondition is that the outside air temperature input from the outside air temperature sensor 18 is within a predetermined temperature range (for example, −10 ° C. or more and less than 40 ° C.), and the operation time after the start of the internal combustion engine 10 is a predetermined time or more (for example, At least one condition that the engine speed input from the rotation detecting device 34 is within a predetermined range (for example, 800 rpm to 2000 rpm) and that the DPF 43 is not being regenerated may be included.

  If it is determined that the precondition is not satisfied (S12: NO), the control device 50 ends the processing. On the other hand, when it is determined that the precondition is satisfied (S12: YES), the control device 50 proceeds to step S13. In step S13, the control device 50 calculates an estimated temperature T2E on the downstream side of the DPF 43 from the measured value of the temperature T1 on the upstream side of the DPF 43, and stores the estimated temperature T2E on the RAM. Specifically, the control device 50 calculates the estimated temperature T2E (t) on the downstream side of the DPF 43 by the following equation (1). Here, K is a first-order lag coefficient. L is the dead time. M is a heat radiation term (DPF heat radiation term) (DPF heat radiation coefficient) of the particulate matter removal filter.

  T2E (t) = [T1 (t−L) × K + T1 (t−L−1) × (1−K)] × M (1)

  Therefore, the estimated temperature T2E (t) on the downstream side of the DPF 43 is smaller than the exhaust gas temperature T1 (t) on the upstream side of the DPF 43 stored in step S11 by the dead time L stored in the RAM before the dead time L. Based on the gas temperature T1 (t-L), the upstream exhaust gas temperature T1 (t-L-1) previously stored, the first-order lag coefficient K, and the DPF radiation term M, It is calculated by equation (1). Note that the dead time L, the first-order delay coefficient K, and the DPF heat radiation term M of the DPF 43 are obtained in advance by actual measurement or CAE (Computer Aided Engineering) analysis, and are stored in the ROM of the control device 50 in advance.

  Here, the temperature T1 of the exhaust gas upstream of the DPF 43 measured in step S11, the temperature T2 of the exhaust gas downstream of the DPF 43, and the estimated temperature T2E downstream of the DPF 43 calculated by the above equation (1). An example of each temperature change will be described with reference to FIGS. The temperatures T1 and T2 of the exhaust gas upstream and downstream of the DPF 43 were measured by operating the internal combustion engine 10 in the transient test mode (NRTC mode).

  As shown in FIG. 3, when the DPF 43 is mounted on the exhaust gas purification device 41, as the operation time of the internal combustion engine 10 advances, the change in the temperature T2 on the downstream side of the DPF 43 changes with the temperature on the upstream side of the DPF 43. It follows the rise or fall of T1 with a predetermined time delay, and rises or falls. On the other hand, the change in the estimated temperature T2E on the downstream side of the DPF 43 calculated by the above equation (1) rises or falls almost synchronously with the rise or fall of the temperature T2 on the downstream side of the DPF 43.

  On the other hand, as shown in FIG. 4, when the DPF 43 is removed from the exhaust gas purification device 41, the change in the temperature T2 on the downstream side of the DPF 43 increases as the operation time of the internal combustion engine 10 advances. Following the rise or fall of the temperature T1 with a slight delay, it rises or falls. On the other hand, the change in the estimated temperature T2E on the downstream side of the DPF 43 follows the rise or fall of the temperature T2 on the downstream side of the DPF 43 with a delay of almost a predetermined dead time, and rises or falls.

  Then, in step S14, the control device 50 generates an error (error) of the measured temperature T2 (t) downstream of the DPF 43 measured in step S11 with respect to the estimated temperature T2E (t) downstream of the DPF 43 calculated in step S13. The absolute value | TD (t) | of the temperature difference) TD (t) is calculated and stored in the RAM. Specifically, control device 50 calculates an absolute value | TD (t) | of error TD (t) by the following equation (2).

  | TD (t) | = | T2 (t) −T2E (t) | (2)

  Subsequently, in step S15, it is determined whether or not the absolute value | TD (t) | of the error TD (t) calculated in step S14 is equal to or greater than a predetermined error threshold TJ. Note that the error threshold value TJ is stored in the ROM of the control device 50 in advance.

  Here, an example of a temperature change of the absolute value | TD (t) | of the error TD (t) calculated by the above equation (2) will be described with reference to FIG. As shown in FIG. 5, when the DPF 43 is mounted on the exhaust gas purification device 41 (when the DPF is present), the absolute value | TD (t) of the error TD (t) calculated by the above equation (2). Is always less than the error threshold TJ (° C.) (for example, 15 ° C.) even during the transient operation of the internal combustion engine 10 as shown by the solid line. Note that the error threshold value TJ is a threshold value for avoiding erroneous determination and for reliably determining that the DPF 43 is mounted. For example, the error threshold value TJ is about twice the maximum value of the absolute value | TD (t) | of the error TD (t) when the DPF 43 is mounted on the exhaust gas purification device 41 (when the DPF is present). Is set.

  On the other hand, when the DPF 43 is removed from the exhaust gas purification device 41 (when no DPF is present), the absolute value | TD (t) | of the error TD (t) calculated by the above equation (2) is represented by a broken line. As shown, during the transient operation of the internal combustion engine 10, a state in which the error threshold TJ (° C.) (eg, 15 ° C.) or more occurs.

  Subsequently, as shown in FIG. 2, when it is determined in step S15 that the absolute value | TD (t) | of the error TD (t) is smaller than a predetermined error threshold TJ (S15: NO), The control device 50 determines that the DPF 43 is mounted on the exhaust gas purification device 41, and ends the process.

  On the other hand, when it is determined in step S15 that the absolute value | TD (t) | of the error TD (t) is equal to or larger than the predetermined error threshold TJ (S15: YES), the control device 50 performs the exhaust gas purification. It is determined that the DPF 43 has been removed from the device 41, and the process proceeds to step S16. In step S16, the control device 50 reads the count value of the abnormality counter from the RAM, counts up the value and stores it again in the RAM, and then proceeds to step S17. That is, the control device 50 accumulates the number of times that the DPF 43 is determined to be removed from the exhaust gas purification device 41. When the control device 50 is started, “0” is assigned to the abnormality counter and stored in the RAM.

  In step S17, the control device 50 reads the count value of the abnormality counter from the RAM, and determines whether or not the count value is equal to or greater than an abnormality determination threshold (predetermined number) NJ. The abnormality determination threshold NJ is stored in the ROM of the control device 50 in advance. For example, the abnormality determination threshold NJ is 10 to 20 times. Then, when it is determined that the count value of the abnormality counter is less than the abnormality determination threshold NJ (S17: NO), the control device 50 ends the processing.

  On the other hand, when it is determined that the count value of the abnormality counter is equal to or greater than the abnormality determination threshold NJ (S17: YES), the control device 50 proceeds to step S18. That is, the control device 50 determines that the DPF 43 has been removed from the exhaust gas purification device 41, and proceeds to step S18. In step S18, the control device 50 reads the DPF removal flag from the RAM, sets the flag to "ON", stores the flag again in the RAM, and ends the process. The DPF removal flag is set to “OFF” and stored in the RAM when the control device 50 is started.

  The control device 50 turns on the filter warning lamp 15 (see FIG. 1) when the DPF removal flag is set to “ON” in another process not shown. For example, when the vehicle diagnostic tool 61 is connected to the connector 16 (see FIG. 1), the DPF removal flag can be reset to “OFF” by a clear command of the DPF removal flag from the vehicle diagnostic tool 61. it can. Further, the filter warning lamp 15 can be set to be turned off by a light-off command from the vehicle diagnostic tool 61 when turned on. Further, the abnormality counter can be reset to “0” by the count clear command from the vehicle diagnosis tool 61.

  Here, the control device 50 and the exhaust gas temperature detection device 36B function as an example of a first temperature acquisition device. The control device 50 and the exhaust gas temperature detection device 36C function as an example of a second temperature detection device. The control device 50 functions as an example of a downstream temperature estimating device, a filter determining device, a calculating unit, a water temperature determining device, and a counting unit. The control device 50, the exhaust gas temperature detection devices 36B and 36C, the exhaust gas purification device 41, the DPF 43, and the water temperature detection device 32 constitute an example of a filter removal detection device.

  As described in detail above, in the internal combustion engine 10 according to the present embodiment, the control device 50 determines the expression (1) based on the temperature T1 (first temperature) on the upstream side of the DPF 43 detected by the exhaust gas temperature detection device 36B. ), An estimated temperature T2E on the downstream side of the DPF 43 is calculated. Then, the control device 50 calculates an absolute value | TD | of an error (temperature difference) TD between the estimated temperature T2E and the temperature T2 (second temperature) on the downstream side of the DPF 43 detected by the exhaust gas temperature detection device 36C according to the following equation. It is calculated by 2).

  Then, control device 50 counts the number of times the absolute value | TD | of error (temperature difference) TD has become equal to or greater than predetermined error threshold TJ. When the cumulative number reaches the abnormality determination threshold (predetermined number) NJ, the DPF removal flag is set to “ON”. That is, the control device 50 determines that the DPF 43 has been removed from the exhaust gas purification device 41.

  This makes it possible to detect that the DPF 43 has been removed from the exhaust gas purification device 41 with a simple configuration in which the exhaust gas temperature detection devices 36B and 36C are arranged on the upstream and downstream sides of the DPF 43, respectively. Further, every time the temperature T2 on the downstream side of the DPF 43 is detected by the exhaust gas temperature detection device 36C, it can be determined whether or not the DPF 43 has been removed based on the temperature T2 on the downstream side of the DPF 43 and the estimated temperature T2E. Even if the measurement interval between the temperatures T1 and T2 on the upstream side and the downstream side of the DPF 43 becomes large, it is possible to suppress erroneous determination.

  Further, every time the temperature T2 on the downstream side of the DPF 43 is detected, it is possible to determine whether or not the DPF 43 has been removed based on the calculated estimated temperature T2E and the temperature T2. It can be detected quickly. Further, the cumulative number of times that the absolute value | TD | of the error (temperature difference) TD between the estimated temperature T2E and the temperature T2 on the downstream side of the DPF 43 becomes equal to or larger than the predetermined error threshold TJ is determined as the abnormality determination threshold (predetermined number) NJ. When it has reached, it is determined that the DPF 43 has been removed from the exhaust gas purification device 41. As a result, erroneous determination can be appropriately suppressed by setting the abnormality determination threshold (predetermined number) NJ to an appropriate number.

  Further, by obtaining the dead time L of the DPF 43, the first-order lag coefficient K, and the DPF heat radiation term M in advance by actual measurement or CAE analysis or the like, the upstream temperature of the DPF 43 stored before the dead time L is stored. The estimated temperature T2E on the downstream side of the DPF 43 is calculated based on T1, the temperature T1 on the upstream side of the DPF 43 stored immediately before the dead time L, the first-order lag coefficient K, and the DPF radiation term. Can be calculated. Thus, each time the temperature T2 on the downstream side of the DPF 43 is detected, it is possible to determine whether or not the DPF 43 has been removed based on the calculated estimated temperature T2E and the temperature T2. Can be detected quickly.

  In the execution conditions for executing the processing after step S13 for determining whether or not the DPF 43 has been removed, the cooling water temperature of the internal combustion engine 10 input from the water temperature detecting device 32 is equal to or higher than a predetermined temperature (for example, about 70 ℃ or more). With this, when it is determined that the temperature of the cooling water for the internal combustion engine 10 is equal to or higher than the predetermined temperature, the estimated temperature T2E on the downstream side of the DPF 43 is calculated, so that the accuracy of the estimated temperature T2E can be improved. , DPF 43 can be determined with high accuracy.

  The filter removal detection device of the present invention is not limited to the configuration, structure, appearance, shape, processing procedure, and the like described in the above embodiment, and various changes, improvements, and modifications can be made without changing the gist of the present invention. Addition and deletion are possible. In the following description, the same reference numerals as those of the internal combustion engine 10 and the like according to the embodiment in FIGS. 1 to 5 denote the same or corresponding parts as the internal combustion engine 10 and the like according to the embodiment.

  (A) For example, in step S11, the control device 50 estimates (calculates) the temperature T1 on the upstream side of the DPF 43 from the following operating condition parameters of the internal combustion engine 10 instead of the exhaust gas temperature detection device 36B. You may make it memorize | store in RAM sequentially. This makes it possible to reduce the number of the exhaust gas temperature detection devices 36B. The operating condition parameters include the engine speed of the internal combustion engine 10 detected by the rotation detecting device 34, the fuel injection amount by each of the injectors 14 </ b> A to 14 </ b> D, the outside air temperature detected by the outside air temperature sensor 18, and detected by the water temperature detecting device 32. At least one of the temperature of the cooling water of the internal combustion engine 10, the supercharging pressure of intake air by a turbocharger (not shown), the presence or absence of regeneration of the DPF 43 for burning and burning particulate matter (PM) deposited on the DPF 43, and the like. It is.

  (B) Also, for example, when the DPF removal flag is set to “ON” in another process (not shown), the control device 50 turns on a speaker (not shown) every predetermined time (for example, every one minute). The voice guidance for notifying that the DPF 43 has been removed may be performed a predetermined number of times (for example, five times).

Reference Signs List 10 internal combustion engine 12 exhaust passage 32 water temperature detector 36B, 36C exhaust temperature detector 43 particulate matter removal filter (DPF)
50 Control device

Claims (4)

A first temperature acquisition device that is arranged in an exhaust gas passage of an internal combustion engine and acquires a first temperature on an upstream side of a particulate matter removal filter that collects particulate matter at predetermined time intervals and stores the temperature in a time-series manner;
A second temperature detection device that detects a second temperature on the downstream side of the particulate matter removal filter at the predetermined time intervals,
Downstream temperature estimation for calculating an estimated temperature on the downstream side of the particulate matter removal filter when the particulate matter removal filter is mounted, based on the first temperature acquired by the first temperature acquisition device. Equipment and
Filter determination for determining whether or not the particulate matter removal filter has been removed based on the estimated temperature calculated by the downstream temperature estimation device and the second temperature detected by the second temperature detection device Equipment and
With
Filter removal detection device. The filter removal detection device according to claim 1,
The downstream temperature estimating device,
The first temperature stored before a predetermined dead time, the first temperature stored one immediately before the dead time, a first-order lag coefficient, and a particulate matter removal filter radiation coefficient, Having a calculating unit to calculate the estimated temperature,
Filter removal detection device. The filter removal detection device according to claim 1 or 2,
A water temperature detection device for detecting a temperature of cooling water for cooling the internal combustion engine,
A water temperature determination device that determines whether the water temperature detected by the water temperature detection device is equal to or higher than a predetermined temperature,
With
The downstream temperature estimating device,
When the water temperature is determined by the water temperature determination device to be equal to or higher than a predetermined temperature, the estimated temperature is calculated.
Filter removal detection device. The filter removal detection device according to any one of claims 1 to 3,
The filter determination device,
An absolute value of a temperature difference between the estimated temperature and the second temperature has a counting unit that counts a cumulative number of times that is equal to or more than a predetermined error threshold,
When the cumulative number counted by the counting unit reaches a predetermined number, it is determined that the particulate matter removal filter has been removed,
Filter removal detection device.

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