Fault diagnosis method and device for engine, vehicle and storage medium

Abstract

The invention provides an engine fault diagnosis method and device, a vehicle and a storage medium. The method comprises the steps that under the condition that a phaser of the engine is in a locking state, the duty ratio of an engine oil control valve of the engine is controlled to be increased from the initial duty ratio to the target duty ratio, so that the phaser is unlocked; adjusting the phase of the unlocked phaser to a target phase, and determining a first difference value between the actual phase of the phaser after adjustment and the target phase of the phaser; wherein the target phase is determined based on the working condition of the engine; determining a fault diagnosis result of the VVT mechanism in the engine according to a second difference value between the actual phase of the phaser and the locking phase of the phaser under the condition that the absolute value of the first difference value is greater than a first angle threshold value for a first duration; wherein the fault diagnosis result comprises a fault diagnosis result in an unlocking stage and a fault diagnosis result in an adjusting stage.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, specifically to a method, device, vehicle, and storage medium for diagnosing engine faults. Background Technology

[0002] VVT (Variable Valve Timing) is a technology used in engines to control the phase of the engine camshaft, changing the opening and closing times of the valves to adapt to different engine operating conditions. This improves engine performance and fuel economy, and reduces emissions of harmful substances such as hydrocarbons and nitrogen oxides. It is a key technology essential for high-performance engines today. VVT consists of a phaser, an oil control valve, and an electromagnet. The working principle of VVT is as follows: the Electronic Control Unit (ECU) transmits the duty cycle to the electromagnet, which controls the oil control valve to switch different oil paths to different chambers of the phaser. The oil pressure drives the phaser to adjust the engine camshaft phase as needed. Due to the complexity of VVT's working principle, VVT malfunctions have always been a critical after-sales issue for engines, but currently, a refined diagnostic method for VVT faults is not available. Summary of the Invention

[0003] This application provides an engine fault diagnosis method, an engine fault diagnosis device, a vehicle, a computer-readable storage medium, and a computer program product, which are beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0004] In a first aspect, embodiments of this application provide a fault diagnosis method for an engine, the method comprising: when the phaser of the engine is in a locked state, controlling the duty cycle of the engine oil control valve to increase from an initial duty cycle to a target duty cycle, thereby unlocking the phaser; adjusting the phase of the unlocked phaser to a target phase, and determining a first difference between the actual phase of the phaser after adjustment and the target phase of the phaser; wherein the target phase is determined based on the engine's operating conditions; and when, for a sustained first duration, the absolute value of the first difference is greater than a first angle threshold, determining a fault diagnosis result of the VVT ​​mechanism in the engine based on a second difference between the actual phase of the phaser and the locked phase of the phaser; wherein the fault diagnosis result includes: a fault diagnosis result during the unlocking phase and a fault diagnosis result during the adjustment phase.

[0005] It is understood that in the fault diagnosis method provided in this application embodiment, when the engine phaser is in a locked state, the duty cycle of the oil control valve is increased from the initial duty cycle to the target duty cycle to unlock the phaser's locking pin. Then, the phase of the unlocked phaser is adjusted to the target phase, and a first difference between the actual phase of the adjusted phaser and the target phase is determined. If the absolute value of the first difference is greater than a first angle threshold for a duration of a first duration, it indicates that the engine's VVT mechanism has a fault. Then, based on a second difference between the actual phase of the phaser and the locked phase, the fault diagnosis result of the VVT ​​mechanism in the engine is determined to be either a fault diagnosis result of the unlocking stage or a fault diagnosis result of the adjustment stage. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0006] In some embodiments, determining the fault diagnosis result of the VVT ​​mechanism in the engine based on a second difference between the actual phase of the phaser and the locked phase of the phaser includes: determining the fault diagnosis result of the VVT ​​mechanism as a fault diagnosis result of the adjustment phase when the absolute value of the second difference is greater than a second angle threshold; determining the fault diagnosis result of the adjustment phase based on the phase change amount within a second time period; or, determining the fault diagnosis result of the VVT ​​mechanism as a fault diagnosis result of the unlocking phase when the absolute value of the second difference is less than or equal to the second angle threshold; determining the fault diagnosis result of the unlocking phase based on the phase change amount within a second time period; wherein the fault diagnosis result includes: sluggish fault and jamming fault.

[0007] It is understood that in the fault diagnosis method provided in this application embodiment, if the absolute value of the first difference between the actual phase and the target phase of the phaser is greater than the first angle threshold and persists for a first duration, it indicates that the VVT ​​mechanism is faulty. If, in the case of a faulty VVT mechanism, the absolute value of the second difference between the actual phase and the locked phase of the phaser is greater than the second angle threshold, it indicates that the phaser has been unlocked, and therefore the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the adjustment phase. If the absolute value of the second difference between the actual phase and the locked phase of the phaser is less than or equal to the second angle threshold, it indicates that the phaser has not been unlocked, and therefore the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the unlocking phase. Then, based on the phase change amount within the second duration, the fault is determined to be a slow fault or a stuck fault. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0008] In some embodiments, determining the fault diagnosis result of the unlocking phase based on the phase change amount within the second time period includes: outputting a stuck fault code for the unlocking phase when the phase change amount within the second time period is less than or equal to the third angle threshold; and outputting a sluggish fault code for the unlocking phase when the phase change amount within the second time period is greater than the third angle threshold.

[0009] It is understood that in the fault diagnosis method provided in this application embodiment, if the phase change within the second time period is less than or equal to the third angle threshold, it indicates that the phase of the phaser has hardly changed, i.e., the VVT ​​mechanism is stuck; therefore, a stuck fault code is output during the unlocking phase. If the phase change within the second time period is greater than the third angle threshold, it indicates that the phase of the phaser has changed, but the change is slow, i.e., the VVT ​​mechanism is sluggish; therefore, a sluggish fault code is output during the unlocking phase. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0010] In some embodiments, determining the fault diagnosis result of the adjustment phase based on the phase change amount within the second time period includes: outputting a jamming fault code under the adjustment phase when the phase change amount within the second time period is less than or equal to the third angle threshold; and outputting a sluggish fault code under the adjustment phase when the phase change amount within the second time period is greater than the third angle threshold.

[0011] It is understood that in the fault diagnosis method provided in this application embodiment, if the phase change within the second time period is less than or equal to the third angle threshold, it indicates that the phase of the phaser has hardly changed, i.e., the VVT ​​mechanism is stuck; therefore, a stuck fault code is output during the adjustment phase. If the phase change within the second time period is greater than the third angle threshold, it indicates that the phase of the phaser has changed, but the change is slow, i.e., the VVT ​​mechanism is sluggish; therefore, a sluggish fault code is output during the adjustment phase. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0012] In some embodiments, the method further includes: if the same fault code is output for N consecutive driving cycles, illuminating the engine malfunction indicator lamp.

[0013] It is understood that in the fault diagnosis method provided in this application embodiment, if the same fault code is output for N consecutive driving cycles after the fault code is output, it indicates that the VVT ​​mechanism has a high probability of having a fault corresponding to that fault code. Then, the fault light is illuminated. This helps to remind the user to have the fault checked in a timely manner, thereby improving maintenance efficiency.

[0014] In some embodiments, the method further includes: if the same fault code is not output for M consecutive driving cycles while the engine malfunction indicator lamp is illuminated, turning off the malfunction indicator lamp.

[0015] It is understood that in the fault diagnosis method provided in this application embodiment, if the engine malfunction indicator lamp is illuminated and the same fault code is not output for M consecutive driving cycles, it indicates that the fault in the VVT ​​mechanism is temporary or has been repaired. Then, the malfunction indicator lamp is turned off. This serves as a helpful reminder to the user that the fault has been repaired.

[0016] In some embodiments, the method further includes deleting the fault code when the malfunction indicator lamp is off and the same fault code has not been output for P consecutive warm-up cycles of the engine.

[0017] It is understood that in the fault diagnosis method provided in this application embodiment, the fault code is deleted after the fault light goes out and the engine has not output the same fault code for P consecutive warm-up cycles. This helps to find an optimal balance between ensuring that the fault has indeed been repaired and avoiding accidental deletion of records due to occasional situations, thereby avoiding over-repair caused by brief, occasional events, and helping maintenance personnel diagnose intermittent faults.

[0018] In some embodiments, when the fault code is a sluggish fault code or a stuck fault code during the unlocking phase, in the process of determining the fault diagnosis result of the VVT ​​mechanism, the duty cycle of the oil control valve controlling the engine is increased from the initial duty cycle to the target duty cycle, which includes: controlling the duty cycle of the oil control valve to increase from the initial duty cycle to a maintained duty cycle and maintaining it for a third duration, and then controlling the duty cycle of the oil control valve to increase from the maintained duty cycle to the target duty cycle; the maintained duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent.

[0019] It is understood that in the fault diagnosis method provided in this application embodiment, when the fault code is a fault code in the unlocking stage, in the process of determining the fault diagnosis result of the VVT ​​mechanism, the way to control the duty cycle of the engine oil control valve to rise from the initial duty cycle to the target duty cycle is as follows: first, control the duty cycle of the oil control valve to rise from the initial duty cycle to the holding duty cycle and maintain it for a third duration, and then control the duty cycle of the oil control valve to rise from the holding duty cycle to the target duty cycle; the holding duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent. In this way, it is beneficial to eliminate the problem of the phaser locking pin mechanism sticking to the wall caused by the duty cycle of the engine oil control valve rising directly from the initial duty cycle to the target duty cycle, which would result in the locking pin mechanism failing to unlock successfully or unlocking late, thus causing the phaser to jam or sluggish.

[0020] Secondly, embodiments of this application provide an engine fault diagnosis device, comprising: a control module configured to, when the phaser of the engine is in a locked state, control the duty cycle of the engine oil control valve to increase from an initial duty cycle to a target duty cycle, thereby unlocking the phaser; an adjustment module configured to adjust the phase of the unlocked phaser to a target phase, and determine a first difference between the actual phase of the adjusted phaser and the target phase of the phaser; wherein the target phase is determined based on the engine's operating conditions; and a determination module configured to, for a first duration, if the absolute value of the first difference is greater than a first angle threshold, determine a fault diagnosis result of the VVT ​​mechanism in the engine based on a second difference between the actual phase of the phaser and the locked phase of the phaser; wherein the fault diagnosis result includes: a fault diagnosis result during the unlocking phase and a fault diagnosis result during the adjustment phase.

[0021] Thirdly, embodiments of this application provide a vehicle, the vehicle including: an engine, an electronic control unit, and a memory; A memory for storing computer-executable instructions or computer programs that run on the electronic control unit; The electronic control unit is used to execute computer-executable instructions or computer programs stored in the memory to implement the engine fault diagnosis method provided in the embodiments of this application.

[0022] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program or computer-executable instructions, which, when executed by an electronic control unit, implements the engine fault diagnosis method provided in embodiments of this application.

[0023] Fifthly, embodiments of this application provide a computer program product, including a computer program or computer-executable instructions, which, when executed by an electronic control unit, implement the engine fault diagnosis method provided in embodiments of this application. Attached Figure Description

[0024] Figure 1 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 1 ; Figure 2 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 2 ; Figure 3 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 3 ; Figure 4 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 4 ; Figure 5 A schematic diagram of an engine fault diagnosis device provided in an embodiment of this application; Figure 6 This is a structural schematic diagram of a vehicle provided in an embodiment of this application. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described below in conjunction with the accompanying drawings. The embodiments described below are only some embodiments of this application, not all embodiments. Therefore, the described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] In the following description, references to “some embodiments” or “other embodiments” describe a subset of all possible embodiments. However, it is understood that “some embodiments” or “other embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0028] In the following description, the terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first" and "second" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0030] VVT (Variable Valve Timing) is a technology used in engines to control the phase of the engine camshaft, changing the opening and closing times of the valves to adapt to different engine operating conditions. This improves engine performance and fuel economy, and reduces emissions of harmful substances such as hydrocarbons and nitrogen oxides. It is a crucial technology essential for modern high-performance engines. VVT consists of a phaser, an oil control valve, and an electromagnet. The working principle of VVT is as follows: the Electronic Control Unit (ECU) transmits the duty cycle to the electromagnet, which controls the oil control valve to switch different oil paths to different chambers of the phaser. The oil pressure drives the phaser to adjust the engine camshaft phase as needed. Due to the complexity of VVT's working principle, VVT malfunctions are consistently a critical type of engine after-sales issue, with phaser sticking (sluggishness) being one of the most common VVT problems.

[0031] Phaser jamming (lag) problems generally fall into three categories: poor cleanliness of the phaser, oil control valve, and solenoid causing phaser jamming (lag) during the unlocking and adjustment phases; low oil pressure driving the phaser causing phaser jamming (lag) during the adjustment phase; and phaser jamming (lag) caused by the locking pin mechanism sticking to the wall during the unlocking phase. Currently, the pain point in the industry regarding phaser jamming (lag) problems is the lack of refined calibration and diagnosis for these three categories of problems, making it impossible to accurately guide after-sales repairs, resulting in low repair efficiency and high repair costs.

[0032] In a related technology, a method for simulating a slow response fault in a VVT system is provided. This method involves recording and maintaining the VVT ​​position after enabling the system, analyzing sampled data, calculating the rate of change, comparing it with a threshold, and determining the fault result. However, this method only provides a simulation method for diagnosing a slow fault mode during phaser adjustment; it is not a diagnostic method for actual vehicle phaser adjustment and cannot diagnose the sub-types of phaser sticking (slowness) problems.

[0033] Another related technology addresses the technical problem of poor diagnostic sensitivity caused by the VVT's target opening degree and actual opening degree continuously exceeding a threshold before triggering a VVT rationality fault judgment. However, it fails to diagnose the sub-types of phaser jamming (sluggishness) problems and does not mention how to solve phaser jamming (sluggishness) problems from a data optimization perspective by optimizing the unlocking strategy.

[0034] In view of this, this application provides a method for diagnosing engine faults, the method being applied to an electronic control unit (ECU). Figure 1 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 1 ,like Figure 1 As shown, the method includes steps 101 to 103: Step 101: With the phaser of the engine in a locked state, control the duty cycle of the engine's oil control valve (OCV) to increase from the initial duty cycle to the target duty cycle, so as to unlock the phaser; Step 102: Adjust the phase of the unlocked phaser to the target phase, and determine the first difference between the actual phase of the phaser after adjustment and the target phase of the phaser; the target phase is determined based on the engine operating conditions. Step 103: If the absolute value of the first difference is greater than the first angle threshold during the first duration, determine the fault diagnosis result of the VVT ​​mechanism in the engine based on the second difference between the actual phase of the phaser and the locked phase of the phaser; the fault diagnosis result includes: the fault diagnosis result of the unlocking stage and the fault diagnosis result of the adjustment stage.

[0035] It is understood that in the engine fault diagnosis method provided in this application embodiment, when the engine phaser is in a locked state, the duty cycle of the oil control valve is increased from the initial duty cycle to the target duty cycle to unlock the phaser's locking pin. Then, the phase of the unlocked phaser is adjusted to the target phase, and a first difference between the actual phase of the adjusted phaser and the target phase is determined. If the absolute value of the first difference is greater than a first angle threshold for a duration of a first duration, it indicates that the engine's VVT mechanism has a fault. Then, based on a second difference between the actual phase of the phaser and the locked phase, the fault diagnosis result of the VVT ​​mechanism in the engine is determined to be either a fault diagnosis result of the unlocking stage or a fault diagnosis result of the adjustment stage. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0036] The following sections will describe further optional implementation methods for each of the above steps, as well as related terms.

[0037] In step 101, while the phaser of the engine is locked, the duty cycle of the engine oil control valve is increased from the initial duty cycle to the target duty cycle to unlock the phaser.

[0038] It should be understood that the engine described in this application embodiment is not limited. An engine is a machine that converts the heat energy generated by fuel combustion into mechanical energy. It is the power source of a car and is responsible for driving the vehicle. In this application embodiment, the phaser in the engine is not limited. In some embodiments, the phaser in the engine is mounted at the front end of the camshaft and is a mechanical actuator that implements the variable valve timing mechanism.

[0039] In this embodiment, the oil control valve of the engine is not limited. In some embodiments, the oil control valve is installed in the cylinder head near the phaser and connected to the phaser via an oil circuit. It is a command executor that controls the operation of the phaser. The oil control valve can be understood as an electro-hydraulic switch controlled by the engine computer. It receives electrical signals from the ECU and, according to the commands, guides pressurized oil to different sides of the phaser rotor. The ECU is the engine control unit.

[0040] In some embodiments, the phaser of the engine being in a locked state can be understood as the phaser's locking pin being in a locked state. In this embodiment, the locking pin is a mechanical locking device integrated inside the phaser. When the engine is turned off or just started, or when the oil pressure is too low, the locking pin extends under the action of a spring force, mechanically locking the phaser's rotor and housing in a fixed initial position (typically with the valve timing in the most retarded or most advanced starting position). This ensures the stability and reliability of the engine during startup.

[0041] In some embodiments, controlling the duty cycle of the engine oil control valve to increase from an initial duty cycle to a target duty cycle includes: directly increasing the duty cycle of the engine oil control valve from the initial duty cycle to the target duty cycle. In other embodiments, controlling the duty cycle of the engine oil control valve to increase from the initial duty cycle to the target duty cycle includes: controlling the duty cycle of the oil control valve to increase from the initial duty cycle to a maintained duty cycle and maintaining it for a third duration, and then controlling the duty cycle of the oil control valve to increase from the maintained duty cycle to the target duty cycle; the maintained duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent.

[0042] It should be understood that, in this embodiment of the application, the direct increase of the duty cycle of the oil control valve controlling the engine from the initial duty cycle to the target duty cycle can be understood as the duty cycle changing instantaneously from the initial duty cycle to the target duty cycle. In this embodiment of the application, the third duration is not limited. For example, in one possible implementation, the third duration is 150 milliseconds to 200 milliseconds.

[0043] In this embodiment of the application, the phrase "maintaining the duty cycle to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent" means that the direction of the pressure difference always remains unchanged (either always the advance chamber height or always the lag chamber height) so as to drive the rotor to rotate stably.

[0044] In some embodiments, the target duty cycle is determined based on the vehicle's oil temperature and oil pressure.

[0045] In step 102, the phase of the unlocked phaser is adjusted to the target phase, and a first difference between the actual phase of the phaser after adjustment and the target phase of the phaser is determined; wherein the target phase is determined based on the operating conditions of the engine.

[0046] In some embodiments, the engine operating conditions include, but are not limited to, at least one of the following: real-time status information such as engine speed, engine load, engine coolant temperature, engine oil temperature, engine oil pressure, engine atmospheric pressure, and engine combustion mode.

[0047] In step 103, if the absolute value of the first difference is greater than the first angle threshold during the first duration, the fault diagnosis result of the VVT ​​mechanism in the engine is determined based on the second difference between the actual phase of the phaser and the locked phase of the phaser; wherein, the fault diagnosis result includes: the fault diagnosis result of the unlocking phase and the fault diagnosis result of the adjustment phase.

[0048] It should be understood that the first duration is not limited in this embodiment. The first duration should not be set too long or too short. Setting the first duration too long may result in low detection efficiency, while setting the first duration too short may result in large detection errors. For example, in one possible implementation, the first duration is 2.5 seconds.

[0049] In this embodiment, the first angle threshold is not limited. The first angle threshold refers to the critical value of the VVT ​​mechanism failure. Exemplarily, in one possible implementation, the first angle threshold is a 15-degree crankshaft angle (CA).

[0050] In some embodiments, determining the fault diagnosis result of the VVT ​​mechanism in the engine based on a second difference between the actual phase of the phaser and the locked phase of the phaser includes: determining the fault diagnosis result of the VVT ​​mechanism as a fault diagnosis result of the adjustment phase when the absolute value of the second difference is greater than a second angle threshold; determining the fault diagnosis result of the adjustment phase based on the phase change amount within a second time period; or, If the absolute value of the second difference is less than or equal to the second angle threshold, the fault diagnosis result of the VVT ​​mechanism is determined as the fault diagnosis result of the unlocking stage; the fault diagnosis result of the unlocking stage is determined according to the phase change amount within the second time period; wherein, the fault diagnosis result includes: slow fault and jamming fault.

[0051] It is understood that in the engine fault diagnosis method provided in this application embodiment, if the absolute value of the first difference between the actual phase and the target phase of the phaser is greater than the first angle threshold and continues for a first duration, it indicates that the VVT ​​mechanism has a fault. If, in the case of a VVT mechanism fault, the absolute value of the second difference between the actual phase and the locked phase of the phaser is greater than the second angle threshold, it indicates that the phaser has been unlocked, and therefore the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the adjustment phase. If the absolute value of the second difference between the actual phase and the locked phase of the phaser is less than or equal to the second angle threshold, it indicates that the phaser has not been unlocked, and therefore the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the unlocking phase. Then, based on the phase change amount within the second duration, the fault is determined to be a sluggish fault or a stuck fault. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0052] It should be understood that, in the embodiments of this application, the locking phase of the phaser is not limited. The locking phase refers to the state in which the locking pin inside the phaser extends under insufficient oil pressure or specific conditions, mechanically locking the rotor and the housing at a certain fixed angle.

[0053] In this embodiment, the VVT ​​mechanism is not limited. The VVT ​​mechanism refers to the mechanical assembly that realizes variable valve timing. The working principle of the VVT ​​mechanism is as follows: the oil control valve introduces pressurized oil from the engine's main oil passage into the advance or lag chamber of the phaser. The oil pressure drives the rotor to rotate relative to the housing, thereby changing the relative angle between the camshaft and crankshaft, and thus changing the valve opening and closing times. The functions of the VVT ​​mechanism include: adjusting valve timing at low speeds to increase torque and improve acceleration performance; adjusting valve timing at high speeds to increase power and meet intake demands at high speeds; adjusting the valve overlap angle at idle to make idling smoother; and, in conjunction with the exhaust gas recirculation system, reducing nitrogen oxide emissions.

[0054] It should be understood that, in this embodiment, the second angle threshold is not limited. The second angle threshold is used to determine whether the phaser is unlocked. Exemplarily, in one possible implementation, the second angle threshold is 3°CA.

[0055] In this embodiment, the second duration is not limited. The second duration should not be set too long or too short. Setting the second duration too long may result in low detection efficiency; setting the second duration too short may result in large detection errors. For example, in one possible implementation, the second duration is 2 seconds.

[0056] It should be understood that, in the embodiments of this application, the terms "jamming fault" and "slow-motion fault" are not limited. The slow-motion fault refers to a situation where the VVT ​​mechanism (phaser rotor) can respond to commands and adjust, but the adjustment speed is too slow, failing to reach the target angle within the time specified by the ECU. The jamming fault refers to a situation where the VVT ​​mechanism (phaser rotor) is completely jammed in a fixed position due to excessive mechanical resistance, and cannot adjust according to ECU commands.

[0057] In some embodiments, determining the fault diagnosis result of the unlocking phase based on the phase change amount within the second time period includes: outputting a stuck fault code for the unlocking phase when the phase change amount within the second time period is less than or equal to the third angle threshold; and outputting a sluggish fault code for the unlocking phase when the phase change amount within the second time period is greater than the third angle threshold.

[0058] It is understood that in the engine fault diagnosis method provided in this application embodiment, if the phase change within the second time period is less than or equal to the third angle threshold, it indicates that the phase of the phaser has hardly changed, i.e., the VVT ​​mechanism is stuck; therefore, a stuck fault code is output during the unlocking phase. If the phase change within the second time period is greater than the third angle threshold, it indicates that the phase of the phaser has changed, but the change is slow, i.e., the VVT ​​mechanism is sluggish; therefore, a sluggish fault code is output during the unlocking phase. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0059] It should be understood that the third angle threshold is not limited in the embodiments of this application. For example, in one possible implementation, the second angle threshold is 3°CA.

[0060] In this embodiment, the unlocking phase and the adjustment phase are not limited. The working process of the VVT ​​mechanism, from engine start to normal operation, can be clearly divided into an unlocking phase and an adjustment phase. Unlocking is the prerequisite for adjustment, and adjustment is the purpose of unlocking. The unlocking phase refers to the process from the moment the engine starts until the locking pin inside the phaser is completely retracted and the rotor gains freedom. The adjustment phase refers to the process after the locking pin is successfully unlocked, whereby the ECU guides engine oil into the advance or lag chamber through the oil control valve according to the engine operating conditions, dynamically changing the camshaft angle.

[0061] In some embodiments, determining the fault diagnosis result of the adjustment phase based on the phase change amount within the second time period includes: outputting a jamming fault code under the adjustment phase when the phase change amount within the second time period is less than or equal to the third angle threshold; and outputting a sluggish fault code under the adjustment phase when the phase change amount within the second time period is greater than the third angle threshold.

[0062] It is understood that in the engine fault diagnosis method provided in this application embodiment, if the phase change within the second time period is less than or equal to the third angle threshold, it indicates that the phase of the phaser has hardly changed, i.e., the VVT ​​mechanism is stuck; therefore, a stuck fault code under the adjustment phase is output. If the phase change within the second time period is greater than the third angle threshold, it indicates that the phase of the phaser has changed, but the change is slow, i.e., the VVT ​​mechanism is sluggish; therefore, a sluggish fault code under the adjustment phase is output. This is beneficial for subdividing the fault types of the VVT ​​mechanism, thereby accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs.

[0063] For example, in one possible implementation, Figure 2 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 2 ,like Figure 2 As shown, the engine fault diagnosis result can be determined through the following steps 201 to 217: Step 201: Power on the vehicle and start the engine; Step 202: Determine the unlock control flag B-UnlockM; if B-UnlockM=0, proceed to step 203; if B-UnlockM=1, proceed to step 204. Step 203: Execute a one-stage VVT ​​unlocking strategy; Step 204: Execute the two-stage VVT ​​unlocking strategy; Step 205: Determine if the absolute value of the difference between the actual phase of VVT and the target phase is >15°CA and lasts for 2.5s; if so, proceed to step 206; otherwise, proceed to step 217. Step 206: Confirm that there is a fault in VVT and enter the code diagnosis mode; Step 207: Determine if the absolute value of the difference between the actual phase of VVT and the locked phase of VVT is ≤3°CA; if so, proceed to step 208; otherwise, proceed to step 213. Step 208: Determine the VVT ​​unlock diagnostic mode; Step 209: Determine if the actual phase change within 2 seconds is ≤3°CA; if so, proceed to step 210; otherwise, proceed to step 211. Step 210, VVT unlock stuck fault code reported; Step 211, VVT unlock delay fault code reported; Step 212: If the unlock control flag B-UnlockM=0, then B-UnlockM is set to 1; if B-UnlockM=1, then the state is maintained. Step 213, determine the VVT ​​adjustment diagnostic mode; Step 214: Determine if the actual phase change within 2 seconds is ≤3°CA; if so, proceed to step 215; otherwise, proceed to step 216. Step 215, VVT running stuck fault code reported; Step 216, report VVT slow operation fault code; Step 217: Execute normal VVT-PID control logic.

[0064] VVT-PID refers to the proportional-integral-derivative control algorithm used to control VVT mechanisms.

[0065] In some embodiments, the method further includes: if the same fault code is output for N consecutive driving cycles, illuminating the engine malfunction indicator lamp.

[0066] It is understood that in the engine fault diagnosis method provided in this application embodiment, if the same fault code is output for N consecutive driving cycles after a fault code is output, it indicates that the VVT ​​mechanism has a high probability of having a fault corresponding to that fault code. Then, the fault light is illuminated. This helps to remind the user to have the fault checked in a timely manner, thereby improving maintenance efficiency.

[0067] It should be understood that the number of driving cycles (N) is not limited in the embodiments of this application. A driving cycle must include three complete phases: starting, driving, and shutting off. During the driving process, the engine must be fully warmed up and subjected to different load conditions in order to complete a complete self-check of all emission-related components.

[0068] In this embodiment, N is not limited. N should not be set too large or too small. Setting N too large may result in low detection efficiency; setting N too short may result in large detection errors. For example, in one possible implementation, N is 2.

[0069] It should be understood that in the embodiments of this application, the N driving cycles are an observation period set to eliminate false alarms. In the case of the first fault code output, it may only be due to occasional signal interference. When N=1, if it appears a second time, remain vigilant. When N=2, i.e., three consecutive occurrences, a fault is confirmed, and the fault indicator light is illuminated.

[0070] In some embodiments, the method further includes: if the same fault code is not output for M consecutive driving cycles while the engine malfunction indicator lamp is illuminated, turning off the malfunction indicator lamp.

[0071] It is understood that in the engine fault diagnosis method provided in this application embodiment, if the engine fault light is illuminated and the same fault code is not output for M consecutive driving cycles, it indicates that the fault in the VVT ​​mechanism is temporary or has been repaired. Then, the fault light is turned off. This serves as a helpful reminder to the user that the fault has been repaired.

[0072] It should be understood that M is not limited in the embodiments of this application. M should not be set too large or too small. Setting M too large may lead to low detection efficiency; setting M too short may lead to large detection errors (if the malfunction indicator lamp turns off after only one normal test, then when the vehicle generates a false alarm under extreme conditions (such as humidity or brief interference), the malfunction indicator lamp will flash on and off intermittently, causing confusion and anxiety to the driver). For example, in one possible implementation, M is 3.

[0073] It should be understood that in the embodiments of this application, as long as the faulty environment no longer occurs and the system continues to stably pass through M complete and normal driving cycle verifications, the ECU will be certain that the "alarm is cleared" and turn off the fault light.

[0074] In some embodiments, the method further includes deleting the fault code when the fault light is off and the engine has not output the same fault code for P consecutive warm-up cycles.

[0075] It is understood that in the engine fault diagnosis method provided in this application embodiment, the fault code is deleted after the fault light goes out and the engine has not output the same fault code for P consecutive warm-up cycles. This helps to find an optimal balance between ensuring that the fault has indeed been repaired and avoiding accidental deletion of records due to occasional situations, thereby avoiding over-repair caused by brief, occasional events, and helping maintenance personnel diagnose intermittent faults.

[0076] In some embodiments, the malfunction indicator light being off includes the malfunction indicator light not being turned on or the malfunction indicator light being turned on and then turned off.

[0077] It should be understood that, in the embodiments of this application, P consecutive warm-up cycles of the engine refers to the complete warm-up process of the engine starting from a cold start, experiencing a water temperature rise of at least 22°C and reaching above 70°C, and repeating this process continuously P times. Based on the P consecutive warm-up cycles of the engine, the ECU can determine whether a fault is an "occasional phenomenon" or a "permanent fault," which is also a prerequisite for the fault code to be automatically cleared.

[0078] In this embodiment, P is not limited. P should not be set too large or too small. Setting P too large may result in low detection efficiency; setting P too short may result in large detection errors. For example, in one possible implementation, P is 40.

[0079] It should be understood that in the embodiments of this application, the warm-up cycle focuses on engine temperature. A cycle is counted as long as the coolant temperature meets the warm-up conditions from start-up to shutdown (e.g., rises by 22°C and reaches 70°C), regardless of vehicle driving or specific operating conditions. The driving cycle focuses on emissions self-check integrity. It requires the vehicle to operate under specific combinations of operating conditions (start, idle, accelerate, cruise) to allow all sensors and actuators to complete a self-diagnosis.

[0080] In some embodiments, when the fault code is a sluggish fault code or a stuck fault code during the unlocking phase, in the process of determining the fault diagnosis result of the VVT ​​mechanism, the duty cycle of the oil control valve controlling the engine is increased from the initial duty cycle to the target duty cycle, which includes: controlling the duty cycle of the oil control valve to increase from the initial duty cycle to a maintained duty cycle and maintaining it for a third duration, and then controlling the duty cycle of the oil control valve to increase from the maintained duty cycle to the target duty cycle; the maintained duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent.

[0081] It is understood that in the engine fault diagnosis method provided in this application embodiment, when the fault code is a fault code in the unlocking stage, in the process of determining the fault diagnosis result of the VVT ​​mechanism, the way to control the duty cycle of the engine oil control valve to rise from the initial duty cycle to the target duty cycle is as follows: first, control the duty cycle of the oil control valve to rise from the initial duty cycle to the holding duty cycle and maintain it for a third time period, and then control the duty cycle of the oil control valve to rise from the holding duty cycle to the target duty cycle; the holding duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent. In this way, it is beneficial to eliminate the problem of the phaser locking pin mechanism sticking to the wall caused by the control of the engine oil control valve duty cycle to rise directly from the initial duty cycle to the target duty cycle, which would result in the locking pin mechanism failing to unlock successfully or unlocking with delay, and thus causing the phaser to jam or be slow.

[0082] The following describes an exemplary application of the embodiments of this application in a real-world application scenario.

[0083] To address the pain point of phaser jamming (sluggishness) in the aforementioned related technologies, this application proposes a VVT diagnosis and post-fault handling method (i.e., an example of an engine fault diagnosis method). This method provides refined diagnosis of phaser jamming (sluggishness), capable of identifying jamming (sluggishness) problems occurring during the phase adjustment phase and during the unlocking phase, thereby accurately guiding after-sales maintenance and improving maintenance efficiency. Furthermore, this application provides a post-fault handling method that can resolve phaser jamming (sluggishness) caused by the locking pin mechanism adhering to the wall at the data level through optimization of the unlocking strategy, saving on after-sales parts replacement costs.

[0084] In some embodiments, the VVT ​​diagnosis and post-fault handling method provided in this application includes: adding a variable parameter whose unlock control flag is B-UnlockM, where the variable parameter is a Boolean value and its default value is 0. When B-UnlockM=0, the ECU executes a one-stage VVT ​​unlock strategy. When B-UnlockM=1, the ECU executes a two-stage VVT ​​unlock strategy. When the ECU diagnoses a phaser jamming or sluggish fault, the ECU diagnoses a phaser fault in the unlocking stage or the adjustment stage by reading the absolute value of the difference between the actual VVT phase and the VVT ​​lock-up phase. When the absolute value of the difference is less than or equal to 3°CA, the fault diagnosis result of the VVT ​​mechanism is determined to be the fault diagnosis result of the unlocking stage; when the absolute value of the difference is greater than 3°CA, the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the adjustment stage.

[0085] When the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the unlocking stage, the actual phase change of VVT within 2 seconds is read. If the phase change is less than or equal to 3°CA, a VVT unlocking stuck fault code is reported; if the phase change is greater than 3°CA, a VVT unlocking delayed fault code is reported. When the ECU reports a VVT unlocking stuck fault code or a VVT unlocking delayed fault code, the ECU checks the unlocking control flag B-UnlockM. If B-UnlockM=0, then B-UnlockM is set to 1; if B-UnlockM=1, the state is maintained.

[0086] When the fault diagnosis result of the VVT ​​mechanism is the fault diagnosis result of the adjustment stage, read the actual phase change of VVT within 2 seconds. If the phase change is less than or equal to 3°CA, report the VVT ​​running stuck fault code; if the phase change is greater than 3°CA, report the VVT ​​running sluggish fault code.

[0087] When the ECU reports a VVT unlock delay fault code or a VVT unlock sticking fault code, fault code post-processing will be performed simultaneously. This post-processing includes: determining whether a VVT unlock delay fault code or a VVT unlock sticking fault code has been reported for two consecutive driving cycles; if so, the engine malfunction indicator lamp (MIL) will illuminate; if not, the MIL will not illuminate, but the fault code will remain in the ECU. When the MIL does not illuminate, the ECU determines whether the engine has undergone 40 consecutive warm-up cycles without faults; if so, the fault code will be deleted. Simultaneously, B-Unlock will be set to 0, and the ECU will execute a one-stage VVT ​​unlocking strategy; if not, the fault code will not be deleted.

[0088] When the engine malfunction indicator lamp illuminates, the ECU checks if the fault code has not been reported for three consecutive driving cycles. If not, the engine malfunction indicator lamp remains on; if it is, the lamp turns off. It then further checks if the engine has undergone 40 consecutive warm-up cycles without faults. If so, the fault code is cleared. Simultaneously, B-Unlock is set to 0, and the ECU executes a one-stage VVT ​​unlocking strategy; if not, the fault code is not cleared.

[0089] When the ECU reports a VVT sluggish operation fault code or a VVT stuck operation fault code, it will simultaneously perform fault code post-processing. This post-processing includes: determining whether a VVT sluggish operation fault code or a VVT stuck operation fault code has been reported for two consecutive driving cycles; if so, the engine malfunction indicator lamp (MIL) will illuminate; if not, the MIL will not illuminate, but the fault code will remain in the ECU. When the MIL is not illuminated, the ECU will determine whether the engine has undergone 40 consecutive warm-up cycles without faults; if so, the fault code will be deleted; if not, the fault code will not be deleted.

[0090] When the engine malfunction indicator lamp illuminates, the ECU checks if the fault code has not been reported for three consecutive driving cycles. If not, the engine malfunction indicator lamp remains on; if it is, the lamp turns off. It then further checks if the engine has undergone 40 consecutive warm-up cycles without any faults. If so, the fault code is cleared; if not, it remains on.

[0091] In some embodiments, the one-stage VVT ​​unlocking strategy refers to the ECU calculating the unlocking duty cycle based on the difference between the VVT ​​target phase and the VVT ​​lock-up phase, and outputting the unlocking duty cycle signal to the electromagnet to control the oil control valve to switch the oil circuit, thereby unlocking the phaser. During the entire unlocking process, the duty cycle changes instantaneously from 0% to the unlocking duty cycle.

[0092] It should be understood that, in the embodiments of this application, the advantage of the one-stage VVT ​​unlocking strategy is that the duty cycle signal changes instantaneously from 0% to the unlocking duty cycle, resulting in a short phaser unlocking time and thus enabling faster adjustment to the VVT ​​target phase. The disadvantage of the one-stage VVT ​​unlocking strategy is that, taking the intake phaser as an example, the instantaneous change of the duty cycle signal from 0% to the unlocking duty cycle can lead to excessively rapid oil pressure build-up in the advance phase adjustment chamber, while the lag phase adjustment chamber is in a draining state. The pressure difference between the two chambers can easily cause the phaser locking pin mechanism to stick to the wall, especially in engines with high oil pressure designs. If the locking pin mechanism fails to unlock successfully or unlocks late, it may lead to a phaser jamming (sluggish) problem.

[0093] In some embodiments, the two-stage VVT ​​unlocking strategy adds a 150ms-200ms VVT hold bit duty cycle signal to the one-stage VVT ​​unlocking strategy. Specifically, the ECU calculates the unlocking duty cycle based on the difference between the VVT ​​target phase and the VVT ​​lock-up phase. During the entire unlocking process, the duty cycle first changes from 0% to a VVT hold bit duty cycle maintained for 150ms-200ms, and then changes from the VVT ​​hold bit duty cycle to the unlocking duty cycle.

[0094] It should be understood that, in the embodiments of this application, the advantage of the two-stage VVT ​​unlocking strategy lies in the addition of a 150ms-200ms VVT holding position duty cycle signal during the unlocking process. The ECU transmits this signal to the electromagnet to control the oil control valve to switch to the holding position oil circuit. Taking the intake phaser as an example, the phaser's advance phase adjustment oil chamber and lag phase adjustment oil chamber are filled with oil simultaneously, and the pressure difference between the two chambers is consistent. In this way, the phaser locking pin mechanism will not experience wall adhesion. Then, the unlocking duty cycle is executed. This helps to avoid the phaser jamming (slowness) problem caused by the locking pin mechanism adhering to the wall. The disadvantage of the two-stage VVT ​​unlocking strategy is that, compared with the one-stage VVT ​​unlocking strategy, the phaser unlocking time is longer, so the time for the phaser to adjust to the VVT ​​target phase is longer.

[0095] In this embodiment, the advantages of both the one-stage and two-stage VVT ​​unlocking strategies are combined, while avoiding their disadvantages. This embodiment incorporates a post-processing strategy for VVT unlocking delay and jamming faults. When a VVT unlocking delay fault code or a VVT unlocking jamming fault code is repaired, the ECU resets B-UnlockM to 0, and the ECU executes the one-stage VVT ​​unlocking strategy.

[0096] It is understood that the VVT ​​diagnosis and post-fault handling method provided in this application embodiment can achieve the following technical effects: (1) It can accurately diagnose phaser jamming (slowness) problems, identify phaser jamming (slowness) problems that occur during the adjustment stage, and identify jamming (slowness) problems that occur during the unlocking stage. This is beneficial for accurately guiding after-sales maintenance, improving maintenance efficiency, and reducing maintenance costs. (2) In the provided post-fault handling method, the addition of a two-stage VVT ​​unlocking strategy can solve the phaser jamming (slowness) problem caused by the locking pin mechanism sticking to the wall, avoiding the cost loss of after-sales replacement parts repair. (3) In the provided post-fault handling method, according to the manifestation of the engine fault code, the VVT ​​unlocking strategy can be flexibly switched between a one-stage VVT ​​unlocking strategy and a two-stage VVT ​​unlocking strategy, taking into account the advantages of the fast phaser unlocking speed of the one-stage VVT ​​unlocking strategy and the ability of the two-stage VVT ​​unlocking strategy to solve the pin mechanism sticking to the wall.

[0097] like Figure 2 As shown, when the vehicle is powered on and the engine is running, step 202 is executed to determine the unlock control flag B-UnlockM. When B-UnlockM=0, step 203 is executed, and the ECU executes a one-stage VVT ​​unlock strategy; when B-UnlockM=1, step 204 is executed, and the ECU executes a two-stage VVT ​​unlock strategy.

[0098] Then, step 205 is executed to determine if there is a fault in the phaser. It checks if the absolute value of the difference between the actual VVT phase and the target phase (i.e., the target phase determined during the adjustment phase after unlocking) is greater than 15°CA and lasts for 2.5 seconds. If the diagnosis result is negative, step 217 is executed, i.e., the normal VVT-PID control logic is executed. If the diagnosis result is positive, step 206 is executed to determine if there is a fault in the VVT ​​and enter the code diagnosis mode. It should be noted that step 205 is in continuous diagnostic mode throughout the VVT's operation.

[0099] Further, step 207 is executed to determine the VVT ​​fault mode, and it is determined whether the absolute value of the difference between the actual VVT phase and the VVT ​​lock-up phase is less than or equal to 3°CA; if the absolute value of the difference between the actual VVT phase and the VVT ​​lock-up phase is less than or equal to 3°CA, then step 208 is executed to determine the VVT ​​unlock diagnostic mode; further step 209 is executed to determine whether the actual phase change within 2 seconds is less than or equal to 3°CA; if the change is greater than 3°CA, then step 210 is executed, and the engine reports a VVT unlock delay fault code, then step 212 is executed, if the unlock control flag B-UnlockM=0, then B-UnlockM is assigned a value of 1; if B-UnlockM=1, then the state is maintained; if the change is less than or equal to 3°CA, then step 211 is executed, and the engine reports a VVT unlock stuck fault code, then step 212 is executed.

[0100] If the absolute value of the difference between the actual VVT phase and the VVT ​​lock-up phase is greater than 3°CA, then execute the VVT ​​adjustment diagnostic mode determination; further execute step 214 to determine whether the actual phase change within 2 seconds is less than or equal to 3°CA; if the change is greater than 3°CA, then execute step 216, and the engine reports a VVT running sluggish fault code; if the change is less than or equal to 3°CA, then execute step 215, and the engine reports a VVT running stuck fault code.

[0101] Figure 3 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 3 ,like Figure 3 As shown, post-fault handling can be performed through the following steps 301 to 315: Step 301: Report a VVT unlock delay fault code or a VVT unlock stuck fault code; Step 302: Determine if this fault code has been reported for two consecutive driving cycles; if so, proceed to step 303; otherwise, proceed to step 311. Step 303, the engine malfunction indicator lamp illuminates; Step 304: Determine if this fault code is not reported for three consecutive driving cycles; if yes, proceed to step 305; otherwise, proceed to step 310. Step 305, the fault light goes out; Step 306: Determine if there are 40 consecutive warm-up cycles without failure; if yes, proceed to step 307; otherwise, proceed to step 309. Step 307, clear fault codes; Step 308: Set B-UnlockM to 0; Step 309: Fault code not deleted; Step 310, the fault light does not turn off; Step 311, the engine malfunction indicator lamp does not illuminate; Step 312: Determine if there are 40 consecutive warm-up cycles without any faults; if yes, proceed to step 313; otherwise, proceed to step 315. Step 313, clear the fault code; Step 314: Set B-UnlockM to 0; Step 315: Fault code not deleted.

[0102] like Figure 3 As shown, when the ECU reports a VVT unlock delay fault code or a VVT unlock sticking fault code, the ECU performs post-fault processing. Step 302: Determine if the VVT ​​unlock delay fault code or VVT unlock sticking fault code has been reported for two consecutive driving cycles. If the engine reports a VVT unlock delay fault code or VVT unlock sticking fault code for two consecutive driving cycles, proceed to step 303, and the engine malfunction indicator lamp illuminates. Further proceed to step 304: Determine if this fault code has not been reported for three consecutive driving cycles; if so, proceed to step 305, and the engine malfunction indicator lamp turns off, and proceed to step 306: Determine if there are no faults for 40 consecutive warm-up cycles; if so, proceed to step 307, and the fault code is deleted, and proceed to step 308, and B-UnlockM is set to 0; if not, proceed to step 309, and the fault code is not deleted; if the result of determining if this fault code has not been reported for three consecutive driving cycles is no, proceed to step 310, and the engine malfunction indicator lamp does not turn off.

[0103] If the engine fails to report a VVT unlock delay fault code or a VVT unlock sticking fault code for two consecutive driving cycles, proceed to step 311, the engine malfunction indicator lamp will not illuminate, and proceed to step 312 to determine if there are no faults for 40 consecutive warm-up cycles; if the result is yes, proceed to step 313 to delete the fault code, and further proceed to step 314 to set B-UnlockM to 0; if the result is no, proceed to step 315, the fault code will not be deleted.

[0104] Figure 4 A schematic diagram of the implementation process of the engine fault diagnosis method provided in the embodiments of this application. Figure 4 ,like Figure 4 As shown, post-fault handling can be performed through the following steps 401 to 413: Step 401: Report a VVT slow operation fault code or a VVT stuck operation fault code; Step 402: Determine if this fault code has been reported for two consecutive driving cycles; if so, proceed to step 403; otherwise, proceed to step 410. Step 403, the engine malfunction indicator lamp illuminates; Step 404: Determine if this fault code has not been reported for three consecutive driving cycles; if so, proceed to step 405; otherwise, proceed to step 409. Step 405, the fault light goes out; Step 406: Determine if there are 40 consecutive warm-up cycles without failure; if yes, proceed to step 407; otherwise, proceed to step 408. Step 407, clear fault codes; Step 408: Fault code not deleted; Step 409, the fault light does not turn off; Step 410, the engine malfunction indicator lamp does not illuminate; Step 411: Determine if there are 40 consecutive warm-up cycles without any faults; if yes, proceed to step 412; otherwise, proceed to step 413. Step 412, clear the fault code; Step 413: Fault codes are not deleted.

[0105] like Figure 4 As shown, when the ECU reports a VVT sluggish operation fault code or a VVT stuck operation fault code, the ECU performs post-fault processing. Step 402 is executed to determine if the VVT ​​sluggish operation fault code or VVT stuck operation fault code has been reported for two consecutive driving cycles. If the engine reports a VVT unlocking sluggish fault code or a VVT unlocking stuck operation fault code for two consecutive driving cycles, step 403 is executed, and the engine malfunction indicator lamp illuminates. Step 404 is further executed to determine if this fault code has not been reported for three consecutive driving cycles; if so, step 405 is executed, and the engine malfunction indicator lamp turns off. Step 406 is further executed to determine if there are no faults for 40 consecutive warm-up cycles; if so, step 407 is executed, and the fault code is deleted; if not, step 408 is executed, and the fault code is not deleted. If the result of determining if this fault code has not been reported for three consecutive driving cycles is negative, step 409 is executed, and the engine malfunction indicator lamp remains on.

[0106] If the engine fails to report a VVT sluggish or VVT stuck fault code for two consecutive driving cycles, proceed to step 410. If the engine malfunction indicator lamp does not illuminate, proceed to step 411 to determine if there are no faults for 40 consecutive warm-up cycles. If the result is yes, proceed to step 412 to clear the fault code. If the result is no, proceed to step 413 to keep the fault code cleared.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications or substitutions should be covered within the protection scope of this application.

[0108] It should be noted that although the steps of the method in this application are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps; or steps from different embodiments may be combined into a new technical solution. Based on the foregoing embodiments, this application provides an apparatus.

[0109] Figure 5 This is a schematic diagram of an engine fault diagnosis device provided in an embodiment of this application, as shown below. Figure 5 As shown, the engine fault diagnosis device 50 includes: a control module 501, an adjustment module 502, and a determination module 503; wherein, The control module 501 is configured to, when the phaser of the engine is in a locked state, control the duty cycle of the engine oil control valve to increase from an initial duty cycle to a target duty cycle, so as to unlock the phaser; The adjustment module 502 is configured to adjust the phase of the unlocked phaser to a target phase, and determine a first difference between the actual phase of the phaser after adjustment and the target phase of the phaser; wherein the target phase is determined based on the operating conditions of the engine; The determination module 503 is configured to determine the fault diagnosis result of the VVT ​​mechanism in the engine based on the second difference between the actual phase of the phaser and the locked phase of the phaser when the absolute value of the first difference is greater than the first angle threshold for a continuous first duration; wherein the fault diagnosis result includes: the fault diagnosis result of the unlocking phase and the fault diagnosis result of the adjustment phase.

[0110] In some embodiments, the determining module 503 is further configured to determine the fault diagnosis result of the VVT ​​mechanism as the fault diagnosis result of the adjustment phase when the absolute value of the second difference is greater than the second angle threshold; and to determine the fault diagnosis result of the adjustment phase based on the phase change amount within the second time period; or, when the absolute value of the second difference is less than or equal to the second angle threshold, to determine the fault diagnosis result of the VVT ​​mechanism as the fault diagnosis result of the unlocking phase; and to determine the fault diagnosis result of the unlocking phase based on the phase change amount within the second time period; wherein the fault diagnosis result includes: sluggish fault and jamming fault.

[0111] In some embodiments, the determining module 503 is further configured to output a stuck fault code during the unlocking phase if the phase change amount during the second duration is less than or equal to the third angle threshold, and to output a sluggish fault code during the unlocking phase if the phase change amount during the second duration is greater than the third angle threshold.

[0112] In some embodiments, the determining module 503 is further configured to output a jamming fault code during the adjustment phase if the phase change during the second duration is less than or equal to the third angle threshold, and to output a sluggish fault code during the adjustment phase if the phase change during the second duration is greater than the third angle threshold.

[0113] In some embodiments, the engine fault diagnosis device 50 further includes an illumination module; the illumination module is configured to illuminate the engine fault light if the same fault code is output for N consecutive driving cycles when a fault code is output.

[0114] In some embodiments, the engine fault diagnosis device 50 further includes an extinguishing module; the extinguishing module is configured to extinguish the fault light if the same fault code is not output for M consecutive driving cycles when the engine fault light is illuminated.

[0115] In some embodiments, the engine fault diagnosis device 50 further includes a deletion module; the deletion module is configured to delete the fault code when the fault light is off and the engine has not output the same fault code for P consecutive warm-up cycles.

[0116] In some embodiments, when the fault code is a slow fault code or a stuck fault code during the unlocking phase, during the process of determining the fault diagnosis result of the VVT ​​mechanism, the control module 501 is further configured to control the duty cycle of the oil control valve to rise from the initial duty cycle to the holding duty cycle and maintain it for a third duration, and then control the duty cycle of the oil control valve to rise from the holding duty cycle to the target duty cycle; the holding duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent.

[0117] The descriptions of the above device embodiments are similar to those of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the device embodiments of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0118] It should be noted that the module division in the embodiments of this application is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, exist as separate physical units, or have two or more units integrated into one unit. The integrated units can be implemented in hardware, as software functional units, or a combination of software and hardware.

[0119] It should be noted that, in the embodiments of this application, if the above methods are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause an electronic device to execute all or part of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), magnetic disks, or optical disks. Thus, the embodiments of this application are not limited to any specific hardware and software combination.

[0120] This application provides a vehicle, Figure 6 This application provides a schematic diagram of the structure of a vehicle, as shown in the embodiment of the present application. Figure 6 As shown, the vehicle 60 includes an engine 601, an electronic control unit 602, and a memory 603; the memory 603 stores a computer program that can run on the electronic control unit 602, and when the electronic control unit 602 executes the program, it implements the steps in the method provided in the above embodiments.

[0121] It should be noted that the memory 603 is configured to store instructions and applications executable by the electronic control unit 602, and can also cache data to be processed or already processed in the electronic control unit 602 and various modules in the vehicle 60 (e.g., image data, audio data, voice communication data and video communication data), which can be implemented through flash memory or random access memory (RAM).

[0122] This application provides a computer-readable storage medium storing a computer program thereon, which, when executed by an electronic control unit, implements the steps of the method provided in the above embodiments.

[0123] This application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the steps in the method provided in the above-described method embodiments.

[0124] It should be noted that the descriptions of the above storage medium and electronic device embodiments are similar to the descriptions of the above method embodiments, and have similar beneficial effects. For technical details not disclosed in the storage medium and electronic device embodiments of this application, please refer to the descriptions of the method embodiments of this application for understanding.

[0125] It should be understood that the phrases "one embodiment," "an embodiment," or "some embodiments" mentioned throughout the specification mean that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment," "in one embodiment," or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above-described embodiments are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. The descriptions of the various embodiments above tend to emphasize the differences between the various embodiments; their similarities or commonalities can be referred to mutually, and for the sake of brevity, they will not be repeated here.

[0126] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0127] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or electronic device. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0128] In the several embodiments provided in this application, it should be understood that the disclosed electronic devices and methods can be implemented in other ways. The embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple modules or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of electronic devices or modules can be electrical, mechanical, or other forms.

[0129] The modules described above as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules. They may be located in one place or distributed across multiple network units. Some or all of the modules may be selected to achieve the purpose of this embodiment according to actual needs.

[0130] In addition, each functional module in the various embodiments of this application can be integrated into one processing unit, or each module can be a separate unit, or two or more modules can be integrated into one unit; the integrated modules can be implemented in hardware or in the form of hardware plus software functional units.

[0131] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0132] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium.

[0133] Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause an electronic device to execute all or part of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0134] The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

[0135] The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments.

[0136] The features disclosed in the several method or electronic device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method or electronic device embodiments.

[0137] The above are merely embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for diagnosing engine faults, characterized in that, The method includes: When the phaser of the engine is locked, the duty cycle of the engine oil control valve is increased from the initial duty cycle to the target duty cycle to unlock the phaser. Adjust the phase of the unlocked phaser to a target phase, and determine a first difference between the actual phase of the phaser after adjustment and the target phase of the phaser; wherein the target phase is determined based on the operating conditions of the engine; If, for a sustained first duration, the absolute value of the first difference is greater than the first angle threshold, the fault diagnosis result of the VVT ​​mechanism in the engine is determined based on the second difference between the actual phase of the phaser and the locked phase of the phaser; wherein, the fault diagnosis result includes: the fault diagnosis result of the unlocking phase and the fault diagnosis result of the adjustment phase.

2. The fault diagnosis method according to claim 1, characterized in that, The step of determining the fault diagnosis result of the VVT ​​mechanism in the engine based on the second difference between the actual phase of the phaser and the locked phase of the phaser includes: If the absolute value of the second difference is greater than the second angle threshold, the fault diagnosis result of the VVT ​​mechanism is determined to be the fault diagnosis result of the adjustment phase; the fault diagnosis result of the adjustment phase is determined based on the phase change amount within the second time period; or, If the absolute value of the second difference is less than or equal to the second angle threshold, the fault diagnosis result of the VVT ​​mechanism is determined as the fault diagnosis result of the unlocking stage; the fault diagnosis result of the unlocking stage is determined according to the phase change amount within the second time period; wherein, the fault diagnosis result includes: slow fault and jamming fault.

3. The fault diagnosis method according to claim 2, characterized in that, Determining the fault diagnosis result of the unlocking phase based on the phase change within the second time period includes: If the phase change within the second time period is less than or equal to the third angle threshold, output the jamming fault code during the unlocking phase. If the phase change during the second duration is greater than the third angle threshold, a slow fault code for the unlocking phase is output.

4. The fault diagnosis method according to claim 2, characterized in that, Determining the fault diagnosis result of the adjustment phase based on the phase change within the second time period includes: If the phase change within the second time period is less than or equal to the third angle threshold, output the jamming fault code under the adjustment phase. If the phase change during the second duration is greater than the third angle threshold, a slow fault code for the adjustment phase is output.

5. The fault diagnosis method according to any one of claims 1 to 4, characterized in that, The method further includes: If the same fault code is output for N consecutive driving cycles, the engine malfunction indicator lamp will be illuminated.

6. The fault diagnosis method according to claim 5, characterized in that, The method further includes: If the engine malfunction indicator lamp is illuminated, and the same fault code is not output for M consecutive driving cycles, the malfunction indicator lamp will be turned off.

7. The fault diagnosis method according to claim 5, characterized in that, The method further includes: If the fault light is off and the engine has not output the same fault code for P consecutive warm-up cycles, then delete the fault code.

8. The fault diagnosis method according to claim 5, characterized in that, When the fault code is a sluggish fault code or a stuck fault code during the unlocking phase, in the process of determining the fault diagnosis result of the VVT ​​mechanism, the duty cycle of the oil control valve controlling the engine is increased from the initial duty cycle to the target duty cycle, including: After controlling the duty cycle of the oil control valve to rise from the initial duty cycle to the maintained duty cycle and maintain it for a third time period, the duty cycle of the oil control valve is then controlled to rise from the maintained duty cycle to the target duty cycle; the maintained duty cycle is used to ensure that the pressure difference between the advance adjustment oil chamber and the lag adjustment oil chamber of the phaser is consistent.

9. A fault diagnosis device for an engine, characterized in that, The device includes: The control module is configured to, when the phaser of the engine is in a locked state, control the duty cycle of the engine oil control valve to increase from an initial duty cycle to a target duty cycle, so as to unlock the phaser; An adjustment module is configured to adjust the phase of the unlocked phaser to a target phase, and determine a first difference between the actual phase of the phaser after adjustment and the target phase of the phaser; wherein the target phase is determined based on the operating conditions of the engine; The determination module is configured to determine the fault diagnosis result of the VVT ​​mechanism in the engine based on the second difference between the actual phase of the phaser and the locked phase of the phaser when the absolute value of the first difference is greater than the first angle threshold for a continuous first duration; wherein the fault diagnosis result includes: the fault diagnosis result of the unlocking phase and the fault diagnosis result of the adjustment phase.

10. A vehicle, characterized in that, The vehicle includes an engine, an electronic control unit, and a memory; the memory is used to store a computer program running on the electronic control unit; the electronic control unit is used to execute the computer program in the memory to perform the engine fault diagnosis method according to claims 1 to 8.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program is executed by the electronic control unit using the engine fault diagnosis method as described in claims 1 to 8.

12. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by the electronic control unit, the fault diagnosis method for the engine as described in claims 1 to 8 is implemented.

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