Engine and method of diagnosing engine

Abstract

The present application provides an engine capable of improving the fault diagnosis accuracy of NO x An engine and a diagnosis method of the engine capable of improving the fault diagnosis accuracy of NO x sensor. The engine is configured to perform, by control of an electronic control device, NO x x sensor fault diagnosis operation (S103) in which the engine is operated in a state in which the DPF regeneration processing, the EGR stop, and the urea water injection stop are performed. x In the NO x x sensor fault diagnosis operation, detection data of the concentrations (J) (K) detected by the pair of NO x x sensors is transmitted to an engine diagnosis tool outside the engine (S105), and the engine diagnosis tool performs the fault diagnosis of the pair of NO x x sensors based on the detection data (S108). In the diagnosis method of the engine, the fault diagnosis of the NO

Description

Technical Field

[0001] This invention relates to engines and engine diagnostic methods, and more specifically, to a method for improving NO levels. x The accuracy of sensor fault diagnosis in engines and engine diagnostic methods. Background Technology

[0002] Previously, there was a method based on NO in engine exhaust. x NO concentration detection x Engine fault diagnosis of sensors (e.g., see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-241737 (see reference) Figure 4 ) Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Problem Points NO x The accuracy of sensor fault diagnosis may decrease.

[0008] In the engine described in Patent Document 1, the exhaust flow is unstable at low exhaust temperatures, and urea crystals remain in the exhaust passage. Furthermore, while EGR is continuing, NO... x The concentration will decrease, therefore, due to NO x NO detected by the sensor x The accuracy of concentration detection data will decrease. Additionally, when spraying urea solution, the NO content of the SCR will be lower. x Purification function, NO x The concentration detection data for NO can vary significantly. Therefore, NO x The accuracy of sensor fault diagnosis may decrease.

[0009] The objective of this invention is to provide a method that can improve NO x The accuracy of sensor fault diagnosis in engines and engine diagnostic methods.

[0010] Technical means for solving problems

[0011] The main structure of the invention in this application is as follows.

[0012] (The invention of claim 1)

[0013] An engine, characterized in that the engine is configured to: perform NO424 ... x Sensor fault diagnosis operation, in this NO x During sensor fault diagnosis operation, the pair of NO... x A pair of NO detected by the sensor x The concentration detection data is sent to an external engine diagnostic tool, which then performs a pair of NO tests based on this data. x Sensor fault diagnosis.

[0014] (The invention of claim 3)

[0015] A diagnostic method for an engine, characterized by using an electronic control device to control the engine to perform NO removal processes accompanied by DPF regeneration, EGR shutdown, and urea injection shutdown. x Sensor fault diagnosis operation, in this NO x During sensor fault diagnosis operation, a pair of NO sensors on the upstream and downstream sides of the SCR exhaust system will be used for fault diagnosis. x A pair of NO detected by the sensor x The concentration detection data is sent to the engine diagnostic tool, and based on the detection data, the engine diagnostic tool performs NO testing. x Sensor fault diagnosis.

[0016] The effects of the invention

[0017] The invention according to claim 1 or 3 can achieve the following effects.

[0018] Effect 1 can increase a pair of NO x The accuracy of sensor fault diagnosis.

[0019] In NO x During sensor fault diagnosis operation, the exhaust gas is heated through DPF regeneration to stabilize the exhaust flow and burn off urea crystals adhering to the exhaust passage. Subsequently, the NO is stopped by EGR. x The concentration increases, therefore, due to a pair of NO x NO detected by sensor x The accuracy of concentration detection data is improved. Furthermore, since urea water injection has stopped, this detection data is unaffected by SCR NO. x The effect of purification function is not easily changed. Thus, by using a pair of highly precise and unchanging NO... x The concentration detection data is sent to the engine diagnostic tool, which can then analyze the NO concentration based on a pair of NO... x The concentration detection data of the pair of NO xSensor fault diagnosis, thereby improving the efficiency of a pair of NO x The accuracy of sensor fault diagnosis.

[0020] Effect 2 allows for the generation of a pair of NO while the exhaust system is mounted on the engine. x Sensor fault diagnosis.

[0021] In NO x During sensor fault diagnosis operation, the pair of NO... x A pair of NO detected by the sensor x The concentration detection data is sent to an external engine diagnostic tool, which then performs a pair of NO tests based on this data. x Sensor fault diagnosis enables NO detection when the exhaust system is mounted on the engine. x Sensor fault diagnosis. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an engine according to an embodiment of the present invention and an engine diagnostic tool for diagnosing the engine.

[0023] Figure 2 It means Figure 1 A block diagram of the engine's electronic control unit and peripheral components such as sensors and actuators connected to the electronic control unit.

[0024] Figure 3 yes Figure 1 A flowchart illustrating the control procedures performed by the engine's electronic control unit during engine fault diagnosis in normal engine operation.

[0025] Figure 4 Is using Figure 1 NO of engine diagnostic tools x Flowchart of control procedures in sensor fault diagnosis (first time). Figure 4 (A) is a flowchart of control based on engine diagnostic tools. Figure 4 (B) is a flowchart of the control of the engine-based electronic control unit.

[0026] Figure 5 Is using Figure 1 Engine diagnostic tools for engine NO x Flowchart of control in sensor fault diagnosis (second time). Figure 5 (A) is a flowchart of control based on engine diagnostic tools. Figure 5 (B) is a flowchart of the control of the engine-based electronic control unit.

[0027] Figure 6Is using Figure 1 NO of engine diagnostic tools x Sensor replacement for NO x A flowchart illustrating the control process during the functional recovery confirmation and diagnostics of an engine with purification function. Figure 6 (A) is a flowchart of control based on engine diagnostic tools. Figure 6 (B) is a flowchart of the control of the engine-based electronic control unit. Detailed Implementation

[0028] Figures 1 to 6 This diagram illustrates an engine and a method for diagnosing an engine according to an embodiment of the present invention. In this embodiment, a vertical inline multi-cylinder diesel engine and a method for diagnosing the engine are described.

[0029] like Figure 1 As shown, the engine (1) has an electronic control device (8), an intake device (10), a fuel supply device (11), and an exhaust device (12). An engine cooling fan (1c) is arranged on the front side of the engine (1), and a flywheel (1d) is arranged on the rear side of the engine (1).

[0030] The electronic control unit (8) is the engine ECU. ECU is short for Electronic Control Unit.

[0031] The intake device (10) includes, in sequence from the upstream side of the intake path, an air filter (10a), an intake throttle valve (10b), an intake sensor (10c), and an intake manifold (10d). The opening and closing timing and opening degree of the intake throttle valve (10b) are controlled by an electronic control unit (8). The intake flow rate and intake temperature are detected by the intake sensor (10c). In addition, EGR is performed from the exhaust device (12) to the intake device (10) via the EGR device (5). EGR is short for exhaust gas recirculation. The EGR device (5) includes, in sequence from the upstream side of the EGR, an EGR cooler (5a) and an EGR valve (5b), the opening and closing of which is controlled by the electronic control unit (8).

[0032] like Figure 1 As shown, the fuel supply device (11) is common rail type, having a common rail (11a) and fuel injectors (11b) that inject fuel into each cylinder (1a).

[0033] The fuel injector (11b) is controlled by the electronic control unit (8) to open the valve at a specified time and inject a specified amount of fuel. The amount of fuel injected is adjusted based on the accelerator position detected by the accelerator sensor (13) and the actual engine speed detected by the engine speed sensor (14) and through the governor function of the electronic control unit (8).

[0034] In addition, under the control of the electronic control device (8), the fuel injector (11b) performs re-injection in addition to main injection during DPF regeneration. Furthermore, after-injection can also be performed between main injection and re-injection.

[0035] like Figure 1 As shown, the exhaust device (12) has an exhaust manifold (12a), DOC (6a), DPF (6), urea water injector (9), SCR (7) and ASC (7a) in sequence from the upstream side of the exhaust. DOC (6a) and DPF (6) are housed in the DPF housing (6b), and SCR (7) and ASC (7a) are housed in the SCR housing (7b). A mixing passage (12b) is provided between the DPF housing (6b) and the SCR housing (7b). A urea water injector (9) is arranged on the upstream side of the mixing passage (12b). Urea water (9a) injected from the urea water injector (9) into the mixing passage (12b) mixes with the exhaust (15) and is supplied to the SCR (7).

[0036] DOC is short for diesel oxidation catalyst, which oxidizes CO (carbon monoxide) and NO (nitric oxide) in exhaust gas (15). During DPF regeneration, the post-injection fuel or re-injection fuel injected from the fuel injector (11b) is catalytically combusted, which raises the temperature of exhaust gas (15) and burns away PM accumulated in DPF (6). PM is short for particulate matter.

[0037] DPF is short for Diesel Particulate Filter, used to capture particulate matter (PM) in exhaust gases.

[0038] SCR is short for Selective Catalytic Reduction catalyst. It utilizes urea water (9a) injected from the urea water injector (9) into the exhaust gas (15) to cause the SCR (7) to adsorb ammonia, which is then used as a reducing agent to reduce NO in the exhaust gas. x (Nitrogen oxides) produce N2 (nitrogen gas) and H2O (water vapor).

[0039] ASC is short for ammonia purification oxidation catalyst, used to prevent the leakage of NH3 (ammonia).

[0040] like Figure 1 As shown, the exhaust device (12) has, in sequence from the upstream side of the exhaust, a DOC inlet-side exhaust temperature sensor (6c), a DPF inlet-side exhaust temperature sensor (6d), an exhaust differential pressure sensor (6e), a DPF outlet-side exhaust temperature sensor (6f), and an SCR (7) for the NO on the upstream side of the exhaust. xSensor (3), SCR inlet side exhaust temperature sensor (7c), NO on the downstream side of SCR (7) exhaust x Sensor (4), during normal engine operation, performs SCR (7)-based NO measurement in conjunction with EGR and urea water injection. x Reduce operation, and when the PM accumulation reaches the amount necessary to start regeneration by detecting the differential pressure between the inlet and outlet of DPF (6) based on the exhaust differential pressure sensor (6e), and when the DOC (6) reaches its activation temperature based on the heating of exhaust (15), DPF regeneration process is started.

[0041] like Figure 1 As shown, urea water (9a) in urea water tank (9b) is pumped by urea water pump (9c) to urea water injector (9). Urea water injector (9) is controlled by electronic control device (8), which opens the valve at a specified time and injects a specified amount of urea water (9a) into mixing passage (12b). The injection volume of urea water (9a) is based on a pair of NO... x The pair of NO detected by sensors (3) and (4) x The concentration (J) (K) or the intake flow rate detected by the intake sensor (10c) is calculated by the arithmetic unit of the electronic control unit (8) of the engine (1). A urea water level sensor (9d) and a urea water temperature sensor (9e) are installed in the urea water tank (9b). The electronic control unit (8) of the engine (1) causes the display device (1b) of the engine (1) to display the replenishment of urea water (9a) and suggestions for preventing the freezing of urea water (9a).

[0042] like Figure 1 As shown, the electronic control unit (8) of the engine (1) is connected to the display unit (1b) of the engine (1). The display unit (1b) of the engine (1) is located on the control panel such as the instrument panel of the engine-mounted machinery, and displays the information described later. Figure 3 Engine fault diagnosis (S6), etc.

[0043] Engine-mounted machinery refers to agricultural or construction machinery that is mounted on an engine (1). The type of machinery includes tractors and excavators, while the type of machinery includes engine generators.

[0044] The display device (1b) of the engine (1) can use a liquid crystal display, an organic EL display, etc. EL is short for electroluminescent.

[0045] The following is a summary of the diagnostic sequence of the engine (1) performed by the electronic control unit (8) of the engine (1).

[0046] like Figure 3As shown, the electronic control unit (8) of the engine (1) performs fault diagnosis (S4) of the engine (1) during normal engine operation. When performing fault determination (S5) of the engine (1), the display device (1b) of the engine (1) displays the engine fault display (S6) and simultaneously displays NO. x Recommendations for sensor fault diagnosis.

[0047] The user-appointed maintenance personnel confirmed that the engine-mounted machinery displayed (S6) was undergoing a NO inspection. x For sensor fault diagnosis, maintenance personnel use engine diagnostic tools (2) to check the NO signal via the electronic control unit (8) of the engine (1). x Sensor fault diagnosis operation (S103) (S203), and based on NO x The NO obtained from sensor fault diagnosis (S108) (S208) x The sensor fault determination display (S110) (S210) confirmation is used to replace NO. x Sensor, then, Figure 6 (A) NO x Sensor replacement for NO x Functional recovery confirmation diagnosis of the engine with purification function (S309).

[0048] Furthermore, after determining the fault of the engine (1) (S5), the output of the engine (1) is limited by the electronic control device (8) of the engine (1), so that the engine-mounted machinery cannot operate, thereby guiding the user to entrust maintenance personnel to perform NO. x Sensor fault diagnosis.

[0049] like Figure 1 As shown, the engine (1) has: a pair of NO on the upstream side and the downstream side of the exhaust of the DPF (6), SCR (7), and SCR (7). x Sensors (3) and (4), electronic control device (8), EGR device (5) and urea water injector (9).

[0050] like Figure 3 As shown, in this engine (1), the fault diagnosis (S4) of the normally operating engine (1) is performed by the electronic control unit (8) of the engine (1) based on the NO of the SCR (7) during engine operation. x The purification rate is used to determine the fault of the engine (1) (S5), and the determination result is displayed on the display device (1b) of the engine (1) (S6).

[0051] Normal operation means, except for Figure 4 (B) Figure 5(B) NO x Sensor fault diagnosis operation (S103) (S203) and Figure 6 (B) NO x The engine's function recovery confirmation operation after sensor replacement (S303) is performed in operation other than normal operation, including NO based on EGR and urea water injection. x Reduce processing speed.

[0052] like Figure 4 (B) Figure 5 As shown in (B), the engine (1) is configured such that, under the control of the electronic control device (8), NO is generated by DPF regeneration treatment, EGR shutdown, and urea water injection shutdown. x Sensor fault diagnosis operation (S103) (S203), in this NO x During the sensor fault diagnosis operation (S103) (S203), the above-mentioned pair of NO... x The pair of NO detected by sensors (3) and (4) x The detection data of NO concentration (J) (K) is sent to the engine diagnostic tool (2) (S105) (S205) outside the engine (1), and the engine diagnostic tool (2) performs the above-mentioned pair of NO based on the detection data. x Fault diagnosis of sensors (3) and (4) (S108) (S208).

[0053] The following effects can be achieved in this engine.

[0054] That is, in Figure 4 (B) Figure 5 (B) NO x In the sensor fault diagnosis operation (S103) (S203), the exhaust gas temperature is increased through DPF regeneration treatment to stabilize the exhaust flow and burn off the urea crystals adhering in the exhaust passage (12c), thereby stopping the NO through EGR. x The concentration increases, therefore, due to a pair of NO x NO detected by sensors (3) and (4) x The accuracy of the concentration (J) (K) detection data is improved. Furthermore, since the urea water injection stops, this detection data is unaffected by the NO concentration of SCR (7). x The effect of purification function is not easily changed. Thus, by using a pair of highly precise and unchanging NO... x The detection data of concentration (J) (K) is sent to the engine diagnostic tool (2) (S105) (S205), such as Figure 4 (A) Figure 5 As shown in (A), in the engine diagnostic tool (2), it is possible to determine the relationship between a pair of NOs. xThe detection data of NO concentration (J) (K) were used to perform the above pair of NO... x Fault diagnosis of sensors (3) and (4) (S108) (S208) can improve the efficiency of a pair of NO sensors. x Accuracy of fault diagnosis (S108) (S208) of sensors (3) and (4).

[0055] In addition, the following effects can also be achieved in this engine.

[0056] like Figure 4 (A) Figure 5 As shown in (A), in NO x During the sensor fault diagnosis operation (S103) (S203), the above-mentioned pair of NO... x The pair of NO detected by sensors (3) and (4) x The detection data of NO concentration (J) (K) is sent to the engine diagnostic tool (2) (S105) (S205) outside the engine (1), and the engine diagnostic tool (2) performs the above-mentioned pair of NO based on the detection data. x Fault diagnosis of sensors (3) and (4) (S108) (S208), therefore, is able to Figure 1 The illustrated exhaust device (12) performs NO emission when mounted on the engine (1). x Fault diagnosis of sensors (3) and (4).

[0057] Figure 4 (A) Figure 5 (A) shows the accompanying NO x The DPF regeneration process in sensor fault diagnosis operation (S103) (S203) differs from the DPF regeneration process during normal operation, and is performed even when the PM buildup has not reached the amount necessary to initiate regeneration. This DPF regeneration process is the same as during normal operation, in... Figure 1 After the exhaust temperature on the inlet side of the DOC (6a) reaches the activation temperature of the DOC (6a), it is re-injected by the fuel injector (11b). When the exhaust temperature on the inlet side of the DOC (6a) is low, the exhaust temperature on the inlet side of the DOC (6a) is raised to the activation temperature of the DOC (6a) by reducing the opening of the intake throttle valve (10b), increasing the main injection fuel, and performing post-injection.

[0058] Furthermore, in the case of an exhaust pipe fuel injection valve, DPF regeneration can also be performed by exhaust pipe injection through the exhaust pipe of the exhaust pipe fuel injection valve, instead of re-injection by the fuel injector (11b).

[0059] like Figure 6As shown in (B), the engine is configured to perform NO treatment accompanied by DPF regeneration, EGR shutdown, and urea water injection under the control of an electronic control unit (8). x Sensor replacement for NO x The purification function engine's function recovery confirmation operation (S303) will be performed in this operation, during which the pair of NO... x The pair of NO detected by sensors (3) and (4) x The detection data of NO concentration (J) (K) is sent (S305) to the engine diagnostic tool (2), and the engine diagnostic tool (2) performs NO testing based on the detection data. x Sensor replacement for NO x Functional recovery confirmation diagnosis of the engine with purification function (S309).

[0060] The following effects can be achieved in this engine.

[0061] That is, in Figure 6 (B) NO x Sensor replacement for NO x During the engine's function recovery confirmation operation (S303) with purification function, the exhaust gas is heated through DPF regeneration treatment, the exhaust flow is stabilized, and the exhaust gas is burned off. Figure 1 The urea crystals adhering in the exhaust passage (12c) shown are stopped by the EGR to prevent NO from escaping. x The concentration increases, therefore, by Figure 6 (B) shows a pair of NO x NO detected by sensors (3) and (4) x The accuracy of the concentration (J) (K) detection data is improved. This is achieved by using a pair of high-precision NO... x The concentration (J) (K) is sent as detection data (S305) to the engine diagnostic tool (2), such as Figure 6 As shown in (A), in the engine diagnostic tool (2), it is possible to determine the relationship between a pair of NOs. x The detection data of NO concentration (J) (K) were used for NO x The engine function recovery confirmation diagnostic after sensor replacement (S309) thus confirms the NO in the engine diagnostic tool (2). x Sensor replacement for NO x The accuracy of the engine function recovery confirmation diagnosis (S309) with purification function has been improved.

[0062] Next, the diagnostic method for the engine (1) will be explained.

[0063] The diagnosis of the engine (1) is performed in the following order: Figure 3Fault diagnosis (S4) of the normally operating engine (1); NO x Sensor fault diagnosis (S108) (S208); based on Figure 4 (A) Figure 5 (A) NO x The sensor fault determination display (S110) (S210) confirms the NO process. x Sensor replacement; and Figure 6 (A) NO x Sensor replacement for NO x Functional recovery confirmation diagnosis of the engine with purification function (S309).

[0064] First, such as Figure 3 As shown, through the electronic control unit (8) of the engine (1), the NO based on the SCR (7) during engine operation... x The purification rate is used to perform fault diagnosis on the normally operating engine (1) (S4). After the fault determination of the engine (1) is performed (S5), the display device (1b) of the engine (1) displays the fault determination of the engine (S6) and simultaneously displays NO. x Recommendations for sensor fault diagnosis.

[0065] Next, the user-appointed maintenance personnel confirmed the above display (S6) on the display device (1b) of the engine (1) to perform NO. x Sensor fault diagnosis, such as Figure 4 As shown in (B), the maintenance personnel control the engine (1) through the electronic control device (8) to perform NO treatment accompanied by DPF regeneration, EGR shutdown, and urea water injection shutdown. x Sensor fault diagnosis operation (S103), in this NO x During sensor fault diagnosis operation (S103), a pair of NO sensors located on the upstream and downstream sides of the SCR (6) will be used. x The pair of NO detected by sensors (3) and (4) x The detection data of concentration (J) (K) is sent (S105) to the engine diagnostic tool (2), such as Figure 4 As shown in (A), based on the above test data, the NO test was performed by the engine diagnostic tool (2). x Sensor fault diagnosis (S108).

[0066] The diagnostic method for this engine can achieve the following results.

[0067] That is, in Figure 4 (B) NO xDuring sensor fault diagnosis operation (S103), the exhaust gas temperature is increased through DPF regeneration treatment to stabilize the exhaust flow and burn off urea crystals adhering to the exhaust passage (12c). Subsequently, NO is stopped by EGR. x The concentration increases, therefore, due to a pair of NO x NO detected by sensors (3) and (4) x The accuracy of the concentration (J) (K) detection data is improved. Furthermore, since the urea water injection stops, this detection data is unaffected by the NO concentration of SCR (7). x The effect of purification function is not easily changed. Thus, by using a pair of highly precise and unchanging NO... x The detection data of concentration (J) (K) is sent to the engine diagnostic tool (2) (S105) (S205), such as Figure 4 As shown in (A), in the engine diagnostic tool (2), it is possible to determine the relationship between a pair of NOs. x The detection data of NO concentration (J) (K) were used to perform the above pair of NO... x Fault diagnosis of sensors (3) and (4) (S108) thereby improving the efficiency of a pair of NO x Accuracy of fault diagnosis (S108) of sensors (3) and (4).

[0068] The following effects can also be achieved in the diagnostic method for this engine.

[0069] like Figure 4 As shown in (A), in NO x During the sensor fault diagnosis operation (S103) (S203), the above-mentioned pair of NO... x The pair of NO detected by sensors (3) and (4) x The detection data of NO concentration (J) (K) is sent to the engine diagnostic tool (2) (S105) (S205) outside the engine (1), and the engine diagnostic tool (2) performs the above-mentioned pair of NO based on the detection data. x Fault diagnosis of sensors (3) and (4) (S108) (S208), therefore, is able to Figure 1 The exhaust device (12) shown is used to discharge NO when mounted on the engine (1). x Fault diagnosis of sensors (3) and (4) (S108) (S208).

[0070] like Figure 4 As shown in (A), in the engine diagnostic tool (2), in the above pair of NO x If the absolute value of the difference between the concentrations (J) and (K) exceeds the specified threshold (L), NO is tested. xSensor fault determination (S109); if the absolute value of the above difference is below a predetermined determination threshold (L), perform the above pair of NO... x Normal determination of sensors (3) and (4) (S111).

[0071] like Figure 4 As shown in (A), in the engine diagnostic tool (2), the NO x Sensor fault determination (S109) or a pair of NO x The normal determination (S111) of sensors (3) and (4) correspondingly causes... Figure 1 The tool display section (2a) of the engine diagnostic tool (2) shown is used for... Figure 4 (A) NO x The sensor fault determination display (S110) or a pair of NO signals x Normal determination display of sensors (3) and (4) (S112).

[0072] like Figure 4 As shown in (A), during NO... x If the sensor fault determination display (S110) is triggered, a NO test will be performed. x The sensor replacement suggestion is displayed, along with the replacement of a NO. x NO after sensor x The sensor's fault diagnosis suggestions are displayed.

[0073] The repairman confirmed the display and placed a pair of NO... x Replace either of the sensors (3) or (4) with a pre-determined normal NO. x Sensors, and perform Figure 5 (A) shows the replacement of a NO x NO after sensor x Sensor fault diagnosis (S208).

[0074] In addition, such as Figure 4 As shown in (A), when performing a pair of NO x In the case of normal determination display of sensors (3) and (4) (S112), in addition to a pair of NO, x The inspection recommendations for components other than sensors (3) and (4) indicate that the maintenance personnel who confirm the information should inspect sensors such as the SCR inlet side exhaust temperature sensor (7c) and actuators such as the urea water injector (9).

[0075] according to Figure 4 The NO shown in (A) x Sensor fault determination (S109), after performing NO x After the sensor is replaced, such as Figure 5As shown in (B), NO is controlled by the electronic control device (8) to perform DPF regeneration treatment, EGR shutdown, and urea water injection shutdown. x NO after sensor replacement x Sensor fault diagnosis operation (S203), in this NO x During the sensor fault diagnosis operation (S203), the fault diagnosis will be performed by the replaced NO. x The pair of NO sensors (3) x The pair of NO detected by sensors (3) and (4) x The detection data of concentration (J) (K) is sent (S205) to the engine diagnostic tool (2), such as Figure 5 As shown in (A), based on the above test data, NO was tested using engine diagnostic tool (2). x NO after sensor replacement x Sensor fault diagnosis (S208).

[0076] like Figure 5 As shown in (A), in the engine diagnostic tool (2), in the pair of NO x If the absolute value of the difference between concentrations (J) and (K) exceeds the specified judgment threshold (L), then the NO solution that has not been replaced is tested. x Fault determination of sensor (4) (S209); if the absolute value of the above difference is below the specified determination threshold (L), perform a pair of NOs that have been replaced and those that have not been replaced. x Normal determination of sensors (3) and (4) (S211).

[0077] like Figure 5 As shown in (A), in the engine diagnostic tool (2), the NO that was not replaced... x Fault determination of sensor (4) (S209) or a pair of NO sensors that have been replaced and those that have not been replaced. x Corresponding to the normal determination of sensors (3) and (4) (S311), the tool display section (2a) of the engine diagnostic tool (2) is set to check for unreplaced NO. x The fault determination display of sensor (4) (S210) or a pair of NO signs indicating that the sensor has been replaced and has not been replaced. x Normal determination display of sensors (3) and (4) (S212).

[0078] like Figure 5 As shown in (A), during NO... x If the sensor fault determination display (S210) is displayed, proceed with another (unreplaced) NO. x Sensor replacement recommendations and replacement NO. x The diagnostic recommendations for confirming engine function recovery are displayed after the sensor scan.

[0079] The technician confirmed that the displayed number was another (not replaced) NO. x The sensor was replaced with a pre-confirmed NO sensor. x Sensors, and perform Figure 6 The NO shown x Sensor replacement for NO x Diagnostic confirmation of engine function recovery with purification function.

[0080] In addition, such as Figure 5 As shown in (A), when performing a pair of NO x If the normal determination display of sensors (3) and (4) is shown (S212), NO is also performed. x Sensor replacement for NO x The diagnostic suggestion for restoring the engine's purification function indicates that the displayed repair personnel have performed the necessary procedures. Figure 6 The NO shown x Sensor replacement for NO x Diagnostic confirmation of engine function recovery with purification function.

[0081] according to Figure 4 (A) or Figure 5 The NO shown in (A) x Sensor fault determination (S109) or NO not replaced x Fault determination of sensor (4) (S109) (S209), after performing NO x After the sensor is replaced, such as Figure 6 As shown in (B), the engine (1) is controlled by the electronic control device (8) to perform NO treatment accompanied by DPF regeneration, EGR shutdown, and urea water injection. x The engine function recovery confirmation operation after sensor replacement (S303) will be performed by the sensor replacement unit. x A pair of NO sensors x The pair of NO detected by sensors (3) and (4) x The detection data of concentration (J) (K) is sent (S305) to the engine diagnostic tool (2), such as Figure 6 As shown in (A), based on the transmitted data, NO is performed using engine diagnostic tool (2). x Sensor replacement for NO x Functional recovery confirmation diagnosis of the engine with purification function (S309).

[0082] like Figure 6 As shown in (A), in the engine diagnostic tool (2), based on the pair of NO...x The theoretical NO of SCR (7) calculated from the detection data of concentration (J) (K) x Purification rate (E) and actual NO x If the absolute value of the difference in purification rates (F) is below the specified judgment threshold (G), then a NO-targeting procedure is performed. x The engine's purification function is restored, and a functional recovery confirmation determination is made (S310). If the absolute value of the difference exceeds the determination threshold (G), a NO-related test is performed. x The function recovery of the purification function of the engine has not been confirmed (S312).

[0083] like Figure 6 As shown in (A), in the engine diagnostic tool (2), corresponding to the engine function recovery confirmation determination (S311) or the engine function recovery non-confirmation determination (S313), the tool display section (2a) of the engine diagnostic tool (2) is set to NO. x The system displays a confirmation of engine function recovery after sensor replacement (S311) or a confirmation of engine function recovery failure (S313).

[0084] like Figure 6 As shown in (A), when conducting research on NO... x If the engine's purification function does not recover and the confirmation judgment is displayed (S313), a pair of NO checks will also be performed. x The inspection recommendations for components other than sensors (3) and (4) indicate that the maintenance personnel should inspect the SCR inlet side exhaust temperature sensor (7c) and other components such as the urea water injector (9).

[0085] like Figure 1 As shown, the engine diagnostic tool (2) is a portable information terminal device with electronic control functions, such as a laptop or tablet computer, and has: a tool display unit (2a), a fault diagnosis indicator switch (2b), a function recovery confirmation diagnosis indicator switch (2c), and a transceiver unit (2d) that transmits and receives data and signals with the transceiver unit (8a) of the electronic control unit (8) of the engine (1) via wired or wireless means.

[0086] The tool display unit (2a), like the display device (1b) of the engine (1), can use a liquid crystal display, an organic EL display, or the like. In this case, Figure 4 (A) Figure 5 (A) NO x The sensor fault diagnosis display (S110) (S210) and a pair of NO signals are shown. x The sensor's normal determination display (S112) (S212) and other information can be displayed as text information on the tool display unit (2a).

[0087] Alternatively, the tool display unit (2a) can also use an indicator light or an LED. LED is short for Light Emitting Diode. In this case, the above-mentioned display in the tool display unit (2a) can be displayed in a recognizable manner by turning on, flashing, or turning off.

[0088] based on Figures 3-6 The flowchart shown illustrates the diagnostic method for this engine.

[0089] Figure 3 This is a flowchart for fault diagnosis of a normally operating engine.

[0090] The fault diagnosis is performed under the control of the electronic control device (8).

[0091] In step (S1), the upstream NO of the SCR is input to the input section of the electronic control device (8). x Concentration (J), NO downstream of SCR x Concentration (K), other data. Other data refers to the theoretical NO discussed later. x Calculation of purification rate (E), actual NO x The data required for calculating the purification rate (F) and setting the judgment threshold (G) specifically refers to the SCR inlet side exhaust temperature for estimating the catalyst temperature of the SCR (7), the intake flow rate for estimating the exhaust flow rate of the exhaust (15), and the injection volume of urea water (9a) of the urea water injector (9) for estimating the ammonia adsorption of the SCR (7).

[0092] In step (S2), the arithmetic unit of the electronic control device (8) performs theoretical calculations. x The purification rate (E) and the actual NOx purification rate (F) are determined in step (S3), where a judgment threshold (G) is set. The judgment threshold (G) is a positive number.

[0093] In step (S4), when the fault determination conditions of engine (1) are met, the fault determination of engine (1) is performed by the diagnostic unit of electronic control device (8) in step (S5).

[0094] The fault determination condition for engine (1) in step (S4) is the theoretical NO. x Purification rate (E) and actual NO x The absolute value of the difference between the purification rates (F) exceeds the judgment threshold (G). In step (S6), the display indicator of the electronic control device (8) causes the display device (1b) of the engine (1) to display the fault judgment of the engine (1) (S6), and performs NO. x Recommendations for sensor diagnostics are shown.

[0095] Figure 4 It's NOx Flowchart for sensor fault diagnosis (first time).

[0096] The NO x Sensor fault diagnosis (first time) is displayed on the display device (1b) that confirms the engine (1). Figure 3 NO in step (S6) shown x The user recommends that the sensor diagnostics be performed by a maintenance technician using an engine diagnostic tool (2).

[0097] exist Figure 4 In step (S101) shown in (A), based on the maintenance personnel's... Figure 1 The fault diagnosis indicator switch (2b) of the engine diagnostic tool (2) shown is operated by sending a NO signal from the diagnostic command unit of the engine diagnostic tool (2). x The signal for sensor fault diagnosis command.

[0098] exist Figure 4 In step (S102) shown in (B), when the receiving determination unit of the electronic control device (8) of the engine (1) confirms NO... x When receiving the sensor fault diagnosis command signal, in step (S103), the NO is implemented by the operation control unit of the electronic control device (8). x Sensor fault diagnosis in operation. NO. x The sensor fault diagnosis operation is accompanied by the cessation of DPF regeneration, EGR shutdown, and urea water injection. This cessation of DPF regeneration, EGR shutdown, and urea water injection shutdown is based on NO... x The sensor fault diagnosis command signal is automatically generated by the electronic control unit (8) of the engine (1).

[0099] In step (S104), the data acquisition unit of the electronic control device (8) of the engine (1) acquires a pair of SCR upstream NO. x Concentration (J) and NO downstream of SCR x In step (S105), the detection data of concentration (K) is obtained by transferring the above pair of detection data from... Figure 1 The transceiver (8a) of the electronic control device (8) shown sends data to the transceiver (2d) of the engine diagnostic tool (2).

[0100] exist Figure 4 In step (S106) shown in (A), when the receiving determination unit of the engine diagnostic tool (2) confirms that the above-mentioned pair of detection data has been received, in step (S107) the determination threshold setting unit of the engine diagnostic tool (2) sets the determination threshold (L). The determination threshold (L) is a positive number.

[0101] In step (S108), the diagnostic unit of the engine diagnostic tool (2) performs NO testing. x Sensor fault diagnosis.

[0102] NO in step (S108) x NO in sensor fault diagnosis x The criteria for determining sensor failure are: a pair of SCR upstream NO x Concentration (J) and NO downstream of SCR x If the absolute value of the difference between the detection data of concentration (K) exceeds the judgment threshold (L), when this judgment condition is met, in step (S109), the fault judgment unit of the engine diagnostic tool (2) issues a NO. x Sensor fault determination: In step (S110), the display indicator of the engine diagnostic tool (2) causes the tool display unit (2a) to display NO. x The sensor's fault diagnosis is displayed, and a NO is generated. x The sensor replacement recommendation is displayed along with a NO. x NO after sensor replacement x The sensor's fault diagnosis suggestions are displayed.

[0103] exist Figure 4 NO in step (S108) shown in (A) x In sensor fault diagnosis, it is impossible to distinguish a pair of NO... x Which of the sensors (3) and (4) malfunctions, therefore, one of the NOs in step (S110) is... x The sensor replacement recommendation does not specify a pair of NOs. x Which of sensors (3) and (4)? In this case, the maintenance personnel can arbitrarily select a pair of NO sensors. x Any one of sensors (3) and (4) will change the NO. x The sensor was replaced with a NO sensor that has been confirmed to be working properly. x sensor.

[0104] Furthermore, due to a pair of NO x The sensors (3) and (4) bear different heat loads, therefore, in the event that a pair of NO... x If the probability of one of the sensors malfunctioning is high, then in step (S110) a NO... x The sensor replacement recommendation display can also specify a pair of NOs. x NO has a higher probability of failure in sensors (3) and (4). x Sensor. In this case, the maintenance personnel, following the recommended specifications, connected a pair of NO sensors. x The designated NO in sensors (3) and (4) xThe sensor was replaced with a NO sensor that has been confirmed to be working properly. x sensor.

[0105] A NO in step (S110) x The sensor replacement recommendation display shows the NO specified. x The sensor can be a pair of NO x Either of the sensors (3) and (4).

[0106] like Figure 4 As shown in (A), in step (S108) NO x In sensor fault diagnosis, when NO is not met... x Under the condition of determining sensor failure, that is, when NO is on the upstream side of a pair of SCRs. x Concentration (J) and NO downstream of SCR x If the absolute value of the difference between the detection data of concentration (K) is below the judgment threshold (L), in step (S111), the fault determination unit of the engine diagnostic tool (2) makes a pair of NO... x In step (S112), the normal determination of sensors (3) and (4) is performed by the display indicator of the engine diagnostic tool (2) on the tool display (2a) by a pair of NO signals. x The normal determination of sensors (3) and (4) is displayed, and a pair of NO is performed. x Inspection recommendations for components other than sensors (3) and (4) indicate that maintenance personnel are advised to inspect sensors such as the SCR inlet side exhaust temperature sensor (7c) and actuators such as the urea water injector (9).

[0107] Figure 5 (A) (B) is NO x Flowchart for sensor fault diagnosis (second time).

[0108] The NO x The sensor fault diagnosis (second time) confirmed that it was displayed on the tool display (2a) of the engine diagnostic tool (2). Figure 4 (A) shows a NO in step (S110). x The sensor replacement recommendation displayed by the repair technician is to replace a NO. x The sensor was replaced with a NO sensor that has been confirmed to be working properly. x After the sensor, the engine diagnostic tool (2) was used.

[0109] Should Figure 5 The NO shown x Sensor fault diagnosis (second time) is in Figure 4 The NO shown x During the sensor fault diagnosis (first time), a pair of NO sensors were replaced. xAfter one of the sensors, according to... Figure 4 The NO shown x Sensor fault diagnosis (first time) is performed in the same order, except... Figure 5 The steps (S201) to (S212) shown in the instructions are related to the processing of steps (S210) and (S212) other than those shown in the instructions. Figure 4 The NO shown x The last two digits of the sensor fault diagnosis (first time) are the same, and the steps (S101) to (S112) are processed in the same way.

[0110] Figure 5 The steps (S210) and (S212) shown are displayed and Figure 4 The steps (S110) and (S112) shown in (A) differ in the following aspects.

[0111] That is, the display of step (S110) is NO. x Sensor fault diagnosis display, one NO x The sensor replacement recommendation is displayed, along with a NO. x NO after sensor replacement x The sensor's fault diagnosis suggestion indicates that, in contrast, step (S210) is displayed as NO. x Sensor fault diagnosis display, and NO x The diagnostic recommendations for restoring engine function after sensor replacement are displayed.

[0112] Additionally, the display of step (S112) is a pair of NOs. x The sensor's normal operation indicator and a pair of NO signals are displayed. x The inspection recommendations for components other than the sensor are shown, and in contrast, the display of step (S212) is a pair of NO. x The sensor's normal operation display, and NO x The diagnostic recommendations for restoring engine function after sensor replacement are displayed.

[0113] In step (S210), another (unreplaced) NO is performed. x The reason given for recommending sensor replacement is: due to a NO. x The sensor is replaced with a pre-determined, functioning sensor; therefore, NO in step (S209) is... x The sensor malfunction was presumed to have originated from another (unreplaced) NO. x Sensor malfunction. Additionally, NO is performed in step (S210). x The diagnostic recommendation for restoring the function of the replaced engine indicates the following reason: another (unreplaced) NO. xThe sensor was also replaced with a pre-determined normal NO sensor. x Sensor, thus a pair of NO x Sensors (3) and (4) are both normal; NO is expected. x Sensor replacement for NO x The engine's purification function has been restored.

[0114] Additionally, NO is performed in step (S212). x The reason given for the recovery confirmation diagnostic recommendation for the replaced engine is: through a pair of NOs in step (S211). x The sensor's normal detection confirmed a pair of NO... x Sensors (3) and (4) are both normal; NO is expected. x Sensor replacement for NO x The engine's purification function has been restored.

[0115] Figure 6 It's NO x Sensor replacement for NO x A flowchart for confirming and diagnosing the functional recovery of an engine with purification capabilities.

[0116] The NO x The diagnostic confirmation of engine function recovery after sensor replacement is usually confirmed by the display device (1b) on the engine (1). Figure 4 (A) step (S110) or Figure 5 (A) NO in steps (S210) and (S212) shown x Sensor replacement for NO x The diagnostic recommendations for restoring the function of the engine with purification function are shown by the maintenance personnel using the engine diagnostic tool (2).

[0117] exist Figure 6 In step (S301) shown in (A), a signal for confirming engine function recovery is sent from the diagnostic command unit of the engine diagnostic tool (2) based on the instruction operation of the maintenance personnel on the engine diagnostic tool (2).

[0118] exist Figure 6 In step (S302) shown in (B), when the signal of the function recovery confirmation diagnostic command is received by the receiving determination unit of the electronic control device (8) of the engine (1), in step (S303), the function recovery confirmation operation of the engine is implemented by the control of the operation control unit of the electronic control device (8). xThe sensor fault diagnosis operation is accompanied by DPF regeneration, EGR shutdown, and urea injection. The DPF regeneration, EGR shutdown, and urea injection shutdown are automatically performed by the electronic control unit (8) of the engine (1) based on the signal of the engine function recovery confirmation diagnostic command.

[0119] In step (S304), the data acquisition unit of the electronic control device (8) of the engine (1) acquires a pair of SCR upstream NO. x Concentration (J), NO downstream of SCR x In step (S305), the concentration (K) and other detection data are transmitted from the transceiver unit (8a) of the electronic control device (8) to the transceiver unit (2d) of the engine diagnostic tool (2).

[0120] exist Figure 6 In step (S306) shown in (A), when the reception determination unit of the engine diagnostic tool (2) confirms the reception of the above-mentioned detection data, in step (S307), the calculation unit of the engine diagnostic tool (2) calculates the theoretical NO. x Purification rate (E) and actual NO x Purification rate (F), in step (S308), the determination threshold (G) is set by the threshold setting unit of the engine diagnostic tool (2). The determination threshold (G) is a positive number.

[0121] In step (S309), the engine's function is confirmed and diagnosed by the diagnostic unit of the engine diagnostic tool (2).

[0122] In step (S309), the engine function recovery failure determination condition in the engine function confirmation diagnosis is theoretical NO. x Purification rate (E) and actual NO x If the absolute value of the difference between the purification rates (F) is below the judgment threshold (G), when the judgment condition is met, in step (S310), the function confirmation judgment unit of the engine diagnostic tool (2) makes a function recovery confirmation judgment of the engine, and in step (S311), the display indication unit of the engine diagnostic tool (2) displays the function recovery confirmation judgment of the engine on the tool display unit (2a).

[0123] In step (S310), if the function confirmation determination unit of the engine diagnostic tool (2) makes a function recovery confirmation determination of the engine, the output restriction of the engine (1) is released by the electronic control device (8) of the engine (1).

[0124] like Figure 6As shown in (A), in the engine function recovery confirmation diagnosis in step (S309), if the determination condition for engine function recovery confirmation is not met, that is, in the theoretical NO x Purification rate (E) and actual NO x If the absolute value of the difference between the purification rates (F) exceeds the judgment threshold (G), in step (S312), the fault judgment unit of the engine diagnostic tool (2) makes a judgment that the engine function recovery has not been confirmed. In step (S313), the display indication unit of the engine diagnostic tool (2) makes a judgment that the engine function recovery has not been confirmed on the tool display unit (2a), and performs a pair of NO checks. x Inspection recommendations for components other than sensors (3) and (4) are shown.

[0125] If the user has access to engine diagnostic tools (2), the user can also perform a pair of NO tests themselves. x Fault diagnosis of sensors (3) and (4) and NO x Sensor replacement for engine NO x The purification function has been restored and confirmed through diagnosis.

[0126] Explanation of reference numerals in the attached figures: (1): Engine; (2): Engine diagnostic tool; (2a): Tool display unit; (3): NO on the upstream side of the exhaust. x Sensor, (4): NO on the downstream side of the exhaust x Sensor, (5): EGR device, (6): DPF, (7): SCR, (8): Electronic control device, (9): Urea water injector, (E): Theoretical purification rate, (F): Actual purification rate, (G): Judgment threshold, (J): NO upstream of SCR x Concentration (K): NO downstream of SCR x Concentration (L): Decision threshold; (S103): NO x Sensor fault diagnosis operation, (S105): Send the detection data to the engine diagnostic tool, (S108): NO x Sensor fault diagnosis, (S109): NO x Sensor fault diagnosis, (S110): NO x Sensor fault diagnosis display, (S111): a pair of NO x Normal sensor determination (S112): A pair of NO x Sensor normal condition display, (S203): NO x NO after sensor replacement x Sensor fault diagnosis operation, (S205): Send the test data to the engine diagnostic tool, (S208): NOx NO after sensor replacement x Sensor fault diagnosis, (S209): NO not replaced x Sensor fault diagnosis (S210): Unreplaced NO x Sensor fault diagnosis display (S211): A pair of NO signs indicating replacement completed and not replaced. x Normal sensor determination (S212): A pair of NO signals indicating whether the sensor has been replaced or not. x Sensor normal condition display, (S303): NO x After the sensor was replaced, the engine function was confirmed to be running again. (S305): Send. (S309): Engine function recovery confirmation diagnosis. (S310): Engine function recovery confirmation judgment. (S311): Engine function recovery unconfirmed judgment display. (S312): Engine function recovery unconfirmed judgment. (S313): Engine function recovery unconfirmed judgment display.

Claims

1. An engine, characterized in that, It has: DPF, SCR, and a pair of NO filters located on the upstream and downstream sides of the SCR exhaust. x Sensors, electronic control unit, EGR device, and urea water injector, The engine is configured to, under the control of an electronic control unit, perform NO removal processes accompanied by DPF regeneration, EGR shutdown, and urea-water injection shutdown. x Sensor fault diagnosis operation, in this NO x During sensor fault diagnosis operation, the pair of NO... x A pair of NO detected by the sensor x The concentration detection data is sent to an external engine diagnostic tool, which then performs the corresponding NO concentration analysis based on this data. x Sensor fault diagnosis.

2. The engine according to claim 1, characterized in that, The engine is configured to perform NO removal processes, including DPF regeneration, EGR shutdown, and urea-water injection, under the control of an electronic control unit. x Sensor replacement for NO x The engine's purification function has been restored and confirmed to operate. During this restoration and confirmation operation, the pair of NO... x A pair of NO detected by the sensor x The concentration detection data is sent to the engine diagnostic tool, which then performs NO analysis based on this data. x Sensor replacement for NO x Diagnostic confirmation of engine function recovery with purification function.

3. A method for diagnosing an engine, characterized in that, Through electronic control, the engine performs NO removal processes including DPF regeneration, EGR shutdown, and urea injection shutdown. x Sensor fault diagnosis operation, in this NO x During sensor fault diagnosis operation, a pair of NO sensors on the upstream and downstream sides of the SCR exhaust system will be used for fault diagnosis. x A pair of NO detected by the sensor x The concentration detection data is sent to the engine diagnostic tool. Based on the aforementioned detection data, NO was analyzed using engine diagnostic tools. x Sensor fault diagnosis.

4. The engine diagnostic method according to claim 3, characterized in that, In the engine diagnostic tool, in the pair of NO x If the absolute value of the concentration difference exceeds the prescribed threshold, NO is tested. x Sensor fault determination; if the absolute value of the difference is below a predetermined determination threshold, perform the pair of NO... x Normal sensor detection.

5. The engine diagnostic method according to claim 4, characterized in that, In engine diagnostic tools, the NO... x Sensor fault diagnosis or a pair of NO x The normal sensor reading corresponds to the tool display of the engine diagnostic tool displaying a NO signal. x The sensor's fault diagnosis display or a pair of NO indicators x The sensor's normal operation is displayed.

6. The engine diagnostic method according to claim 4, characterized in that, According to the NO x Sensor fault diagnosis, after performing NO x After the sensor is replaced, NO is controlled by an electronic control device to perform DPF regeneration, EGR shutdown, and urea water injection shutdown. x NO after sensor replacement x Sensor fault diagnosis operation, in this NO x During sensor fault diagnosis operation, the process will be carried out by the replaced NO... x The pair of NO sensors x A pair of NO detected by the sensor x The concentration detection data is sent to the engine diagnostic tool, and based on the detection data, the engine diagnostic tool performs NO testing. x NO after sensor replacement x Sensor fault diagnosis.

7. The engine diagnostic method according to claim 6, characterized in that, In the engine diagnostic tool, in the pair of NO x If the absolute value of the concentration difference exceeds the prescribed threshold, the NO solution that has not been replaced will be tested. x Sensor fault determination; if the absolute value of the difference is below a specified determination threshold, perform a pair of NO checks showing whether the sensor has been replaced or not. x Normal sensor detection.

8. The engine diagnostic method according to claim 7, characterized in that, In the engine diagnostic tool, the NO was not replaced. x The fault diagnosis or replacement of the sensor and the pair of NOs that have not been replaced. x The normal detection of the sensor corresponds to the tool display of the engine diagnostic tool showing the NO sensor if it has not been replaced. x The sensor fault diagnosis display shows either "replaced" or "not replaced" in a pair of NO indicators. x The sensor's normal operation is displayed.

9. The engine diagnostic method according to claim 4 or 7, characterized in that, According to the NO x Sensor fault diagnosis or failure to replace NO x Sensor fault diagnosis, after performing NO x After the sensor is replaced, the engine is controlled by an electronic control unit to perform NO removal processes including DPF regeneration, EGR shutdown, and urea-water injection. x Sensor replacement for NO x The engine's purification function has been restored and confirmed to be running. During this restoration and confirmation process, the engine will be equipped with a replacement NO. x A pair of NO sensors x A pair of NO detected by the sensor x The concentration detection data is sent to the engine diagnostic tool. Based on the sent data, the engine diagnostic tool performs NO testing. x Sensor replacement for NO x Diagnostic confirmation of engine function recovery with purification function.

10. The engine diagnostic method according to claim 9, characterized in that, In engine diagnostic tools, based on the pair of NO... x The theoretical NO of SCR calculated from the concentration detection data x Purification rate and actual NO x If the absolute value of the difference in purification rates is below the specified threshold, then a NO-targeting procedure is performed. x The engine's purification function is restored, and a functional recovery confirmation determination is made. If the absolute value of the difference exceeds the determination threshold, a NO-related test is performed. x The recovery of the engine's purification function has not been confirmed.

11. The engine diagnostic method according to claim 10, characterized in that, In the engine diagnostic tool, corresponding to the engine function recovery confirmation determination or the engine function recovery non-confirmation determination, the tool display section of the engine diagnostic tool is set to NO. x The system displays either a confirmation of engine function recovery after sensor replacement or a confirmation of unrecovered engine function.

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