Engine start-stop control method and device

Abstract

The application provides an engine start-stop control method and device, the method comprising: S1, obtaining engine state, engine speed and coolant temperature, and identifying post-start idle state and vehicle stop demand; S2, in the post-start idle state, determining throttle valve candidate opening degree and exhaust brake butterfly valve candidate opening degree corresponding to vibration noise control and exhaust temperature management according to the engine speed and the coolant temperature, and selecting the corresponding smaller value as the target opening degree; S3, after the vehicle stop demand is identified, the throttle valve and the exhaust brake butterfly valve are first reduced to the first stage opening degree, fuel injection is stopped for the first time length, and then the two are reduced to the second stage opening degree for the second time length and are kept until the engine speed is zero. The device comprises an engine electronic control unit, a throttle valve, an exhaust brake butterfly valve, a water temperature sensor, an engine speed sensor and a fuel injection system. The application can improve idle vibration noise, exhaust temperature management effect and stop smoothness.

Description

Technical Field

[0001] This invention relates to the field of engine start-stop, and in particular to an engine start-stop control method and apparatus. Background Technology

[0002] During the idling phase after engine start-up, especially when the coolant temperature is low, problems such as engine speed fluctuations, excessive vibration and noise, and slow exhaust temperature rise are common. Existing engine control strategies typically control the throttle or exhaust-side valves independently, failing to coordinate the adjustment of the throttle and exhaust brake butterfly valve based on engine speed and coolant temperature, and also making it difficult to simultaneously control engine noise and manage exhaust temperature.

[0003] Existing technology CN107559096A discloses a diesel engine control method and system, which acquires state parameters such as engine speed and coolant temperature after engine start-up to determine whether the engine is in idling mode. In idling mode, it reduces the throttle opening and adjusts the throttle opening according to engine speed fluctuations to improve vibration and noise performance during engine idling. However, this existing technology mainly relies on throttle adjustment and does not disclose the coordinated control of the throttle and exhaust brake butterfly valve during the idling phase after start-up, nor does it incorporate vibration noise control and exhaust temperature management.

[0004] Existing technology CN112443407A discloses a method, engine system, and bus for reducing engine shutdown impact vibration. After detecting engine shutdown conditions, it reduces the opening of the intake-side and exhaust-side shut-off valves and issues a fuel cut-off shutdown command after the valve openings are reduced, thereby reducing impact vibration during engine shutdown. However, this prior art does not disclose further reducing the opening of the intake-side and exhaust-side valves after a second time interval following the cessation of fuel injection and maintaining this reduction until the engine speed reaches zero. It also does not address vibration and noise control or exhaust temperature management during the idling phase after startup.

[0005] Therefore, existing engine control technology lacks a coordinated control scheme that covers idling and shutdown processes after starting. It is difficult to dynamically coordinate the throttle valve and exhaust brake butterfly valve according to engine speed and coolant temperature. Furthermore, when using simple fuel cut-off or single-stage valve closing during shutdown, significant speed changes, impact vibrations, and noise may still occur. Summary of the Invention

[0006] The main objective of this invention is to provide an engine start-stop control method and device. This application determines the target opening degree of the throttle valve and the exhaust brake butterfly valve based on the engine speed and coolant temperature, and coordinates vibration and noise control and exhaust temperature management to maintain a relatively stable operating state of the engine during the idling stage after starting, while improving the exhaust temperature management effect.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an engine start-stop control method, wherein the electronic control unit executes the following steps: S1. Obtain engine operating status, engine speed and coolant temperature, and identify the idling condition and shutdown requirements after engine start-up based on the engine operating status. S2. When the engine is in the idling condition after starting, the target opening of the throttle valve and the target opening of the exhaust brake butterfly valve are determined according to the engine speed and coolant temperature, and the throttle valve and the exhaust brake butterfly valve are controlled to reach the corresponding target openings respectively. S3. When a shutdown request is detected, the throttle valve and exhaust brake butterfly valve are reduced to their corresponding first-stage openings within the first duration. After the first duration ends, the fuel injection device is controlled to stop injecting fuel. After the fuel injection stops for the second duration, the throttle valve and exhaust brake butterfly valve are further reduced to their corresponding second-stage openings, and the fuel injection is kept stopped until the engine speed drops to zero.

[0008] In the preferred embodiment, in step S1, when the electronic control unit simultaneously detects the engine start-up completion signal and the idle mode indicator, it activates vibration and noise optimization control and exhaust temperature management control; when the engine exits the idle mode, it exits vibration and noise optimization control and exhaust temperature management control; the electronic control unit identifies the shutdown requirement based on the received vehicle power-off shutdown signal.

[0009] In the preferred embodiment, in step S2, the target idle speed is obtained by interpolation calculation based on the coolant temperature in the preset coolant temperature and idle speed calibration relationship, and the engine idle speed is controlled according to the target idle speed.

[0010] In the preferred embodiment, in step S2, the vibration and noise control throttle opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset vibration and noise control throttle opening mapping relationship; the vibration and noise control exhaust brake butterfly valve opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset vibration and noise control exhaust brake butterfly valve opening mapping relationship.

[0011] In the preferred scheme, the mapping relationship between the throttle opening for vibration and noise control and the mapping relationship between the exhaust brake butterfly valve opening for vibration and noise control are established in the following way: Multiple engine speed and coolant temperature combinations are set on the engine test bench. The throttle opening and exhaust brake butterfly valve opening are adjusted under each combination. Corresponding engine vibration and noise data are collected. The opening combinations that do not exceed the preset vibration limit and the noise limit are determined. The corresponding opening combinations are stored according to the engine speed and coolant temperature.

[0012] In the preferred embodiment, in step S2, the exhaust temperature management throttle opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset exhaust temperature management throttle opening mapping relationship; and the exhaust temperature management exhaust brake butterfly valve opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset exhaust temperature management exhaust brake butterfly valve opening mapping relationship.

[0013] In the preferred embodiment, in step S2, the smaller value between the throttle opening for vibration and noise control and the throttle opening for exhaust temperature management is determined as the target throttle opening; the smaller value between the exhaust brake butterfly valve opening for vibration and noise control and the exhaust brake butterfly valve opening for exhaust temperature management is determined as the target exhaust brake butterfly valve opening.

[0014] In the preferred embodiment, in step S3, based on the engine speed at the time of identifying the shutdown requirement, interpolation calculations are performed in the preset throttle opening mapping relationship and exhaust brake butterfly valve opening mapping relationship for the first stage of shutdown to obtain the first stage throttle opening and the first stage exhaust brake butterfly valve opening; within a first duration, the throttle is reduced to the first stage throttle opening and the exhaust brake butterfly valve is reduced to the first stage exhaust brake butterfly valve opening; the first duration is pre-calibrated according to the characteristics of the engine model.

[0015] In the preferred embodiment, in step S3, at the end of the first duration, the fuel injection device is immediately controlled to stop injecting fuel and maintain the stopped fuel injection state; after the fuel injection stops for a second duration, the throttle valve is controlled to the minimum controllable opening of the corresponding engine model, and the exhaust brake butterfly valve is controlled to the minimum controllable opening of the corresponding engine model, until the engine speed drops to zero; the second duration is pre-calibrated according to the characteristics of the engine model.

[0016] An engine start-stop control device includes an electronic control unit, a throttle valve, a throttle valve actuator, an exhaust brake butterfly valve, an exhaust brake butterfly valve actuator, a coolant temperature sensor, and a fuel injection device. The throttle valve is located in the engine intake passage, and the throttle valve actuator is used to adjust the throttle valve opening. The exhaust brake butterfly valve is located in the engine exhaust passage, and the exhaust brake butterfly valve actuator is used to adjust the exhaust brake butterfly valve opening. The electronic control unit has signal input terminals for receiving engine operating status, engine speed, coolant temperature and shutdown requirements. The control output terminals of the electronic control unit are respectively connected to the throttle actuator, exhaust brake butterfly valve actuator and fuel injection device. The electronic control unit is used to control the throttle opening and exhaust brake butterfly valve opening based on engine speed and coolant temperature when the engine is idling after starting. It is also used to control the throttle and exhaust brake butterfly valve to the first stage opening, control the fuel injection device to stop injecting fuel, and control the throttle and exhaust brake butterfly valve to the second stage opening after recognizing the need to stop the engine, until the engine speed drops to zero.

[0017] This invention provides an engine start-stop control method and device. During the engine shutdown process, this application sequentially performs a first-stage opening adjustment, stops fuel injection, and a second-stage opening adjustment, so that the intake and exhaust flow and engine speed change smoothly, reducing the impact vibration and noise generated during the shutdown process. The corresponding device can complete idle speed control and shutdown control using the same control link, which has the beneficial effects of continuous control process and adaptability to different engine operating states.

[0018] The technical problem solved by this application is how to coordinate and control the throttle valve and the exhaust brake butterfly valve according to the engine operating status after the engine starts and during idling and shutdown, so as to balance idling vibration and noise, exhaust temperature management and shutdown smoothness. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the basic layout structure of the engine.

[0020] Figure 2 This is a schematic diagram of the engine control strategy in idle mode.

[0021] Figure 3 This is a schematic diagram of the engine shutdown process control strategy.

[0022] Figure 4 This is the overall flowchart of the engine start-stop control method.

[0023] Figure 5 A schematic diagram for determining the target opening degree of the throttle body and the exhaust brake butterfly valve.

[0024] Figure 6 This is a dynamic control curve diagram of the engine shutdown process.

[0025] Figure 7 This is a diagram showing the joint calibration analysis of the throttle valve and the exhaust brake butterfly valve. Detailed Implementation

[0026] Example 1 like Figure 1-7 As shown, an engine start-stop control method comprises the following steps executed by an electronic control unit: S1. Obtain engine operating status, engine speed and coolant temperature, and identify the idling condition and shutdown requirements after engine start-up based on the engine operating status. S2. When the engine is in the idling condition after starting, the target opening of the throttle valve and the target opening of the exhaust brake butterfly valve are determined according to the engine speed and coolant temperature, and the throttle valve and the exhaust brake butterfly valve are controlled to reach the corresponding target openings respectively. S3. When a shutdown request is detected, the throttle valve and exhaust brake butterfly valve are reduced to their corresponding first-stage openings within the first duration. After the first duration ends, the fuel injection device is controlled to stop injecting fuel. After the fuel injection stops for the second duration, the throttle valve and exhaust brake butterfly valve are further reduced to their corresponding second-stage openings, and the fuel injection is kept stopped until the engine speed drops to zero.

[0027] In the preferred embodiment, in step S1, when the electronic control unit simultaneously detects the engine start-up completion signal and the idle mode indicator, it activates vibration and noise optimization control and exhaust temperature management control; when the engine exits the idle mode, it exits vibration and noise optimization control and exhaust temperature management control; the electronic control unit identifies the shutdown requirement based on the received vehicle power-off shutdown signal.

[0028] In the preferred embodiment, in step S2, the target idle speed is obtained by interpolation calculation based on the coolant temperature in the preset coolant temperature and idle speed calibration relationship, and the engine idle speed is controlled according to the target idle speed.

[0029] In the preferred embodiment, in step S2, the vibration and noise control throttle opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset vibration and noise control throttle opening mapping relationship; the vibration and noise control exhaust brake butterfly valve opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset vibration and noise control exhaust brake butterfly valve opening mapping relationship.

[0030] In the preferred scheme, the mapping relationship between the throttle opening for vibration and noise control and the mapping relationship between the exhaust brake butterfly valve opening for vibration and noise control are established in the following way: Multiple engine speed and coolant temperature combinations are set on the engine test bench. The throttle opening and exhaust brake butterfly valve opening are adjusted under each combination. Corresponding engine vibration and noise data are collected. The opening combinations that do not exceed the preset vibration limit and the noise limit are determined. The corresponding opening combinations are stored according to the engine speed and coolant temperature.

[0031] In the preferred embodiment, in step S2, the exhaust temperature management throttle opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset exhaust temperature management throttle opening mapping relationship; and the exhaust temperature management exhaust brake butterfly valve opening is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset exhaust temperature management exhaust brake butterfly valve opening mapping relationship.

[0032] In the preferred embodiment, in step S2, the smaller value between the throttle opening for vibration and noise control and the throttle opening for exhaust temperature management is determined as the target throttle opening; the smaller value between the exhaust brake butterfly valve opening for vibration and noise control and the exhaust brake butterfly valve opening for exhaust temperature management is determined as the target exhaust brake butterfly valve opening.

[0033] In the preferred embodiment, in step S3, based on the engine speed at the time of identifying the shutdown requirement, interpolation calculations are performed in the preset throttle opening mapping relationship and exhaust brake butterfly valve opening mapping relationship for the first stage of shutdown to obtain the first stage throttle opening and the first stage exhaust brake butterfly valve opening; within a first duration, the throttle is reduced to the first stage throttle opening and the exhaust brake butterfly valve is reduced to the first stage exhaust brake butterfly valve opening; the first duration is pre-calibrated according to the characteristics of the engine model.

[0034] In the preferred embodiment, in step S3, at the end of the first duration, the fuel injection device is immediately controlled to stop injecting fuel and maintain the stopped fuel injection state; after the fuel injection stops for a second duration, the throttle valve is controlled to the minimum controllable opening of the corresponding engine model, and the exhaust brake butterfly valve is controlled to the minimum controllable opening of the corresponding engine model, until the engine speed drops to zero; the second duration is pre-calibrated according to the characteristics of the engine model.

[0035] An engine start-stop control device includes an electronic control unit, a throttle valve, a throttle valve actuator, an exhaust brake butterfly valve, an exhaust brake butterfly valve actuator, a coolant temperature sensor, and a fuel injection device. The throttle valve is located in the engine intake passage, and the throttle valve actuator is used to adjust the throttle valve opening. The exhaust brake butterfly valve is located in the engine exhaust passage, and the exhaust brake butterfly valve actuator is used to adjust the exhaust brake butterfly valve opening. The electronic control unit has signal input terminals for receiving engine operating status, engine speed, coolant temperature and shutdown requirements. The control output terminals of the electronic control unit are respectively connected to the throttle actuator, exhaust brake butterfly valve actuator and fuel injection device. The electronic control unit is used to control the throttle opening and exhaust brake butterfly valve opening based on engine speed and coolant temperature when the engine is idling after starting. It is also used to control the throttle and exhaust brake butterfly valve to the first stage opening, control the fuel injection device to stop injecting fuel, and control the throttle and exhaust brake butterfly valve to the second stage opening after recognizing the need to stop the engine, until the engine speed drops to zero.

[0036] Example 2 Further explanation in conjunction with Example 1, such as Figure 1-7 As shown, an engine start-stop control method is executed by the engine electronic control unit. In step S1, the engine electronic control unit obtains the engine status from the engine operation status management unit, the engine speed from the engine speed sensor, and the coolant temperature from the water temperature sensor, and identifies the idle state after starting and the vehicle shutdown requirement based on the engine status. In step S2, when the engine is in the idle state after starting, the target throttle opening and the target opening of the exhaust brake butterfly valve are determined according to the engine speed and coolant temperature, respectively, and opening control commands are sent to the throttle actuator and the exhaust brake butterfly valve actuator. In step S3, when the vehicle shutdown requirement is identified, the throttle and exhaust brake butterfly valve are reduced to the first stage opening within a first duration, and fuel injection is stopped after the first duration ends; after the fuel injection is stopped for a second duration, the throttle and exhaust brake butterfly valve are further reduced to the second stage opening, and fuel injection is stopped until the engine speed drops to zero. (The following will use the term "start-stop control method"...) Indicates the current coolant temperature, in Indicates the current engine speed, in The class symbol represents the throttle opening, in order to The class symbol indicates the opening degree of the exhaust brake butterfly valve, in order to Indicates the first duration, in This indicates the second duration. Among them, and These represent the first-stage opening of the throttle valve and the first-stage opening of the exhaust brake butterfly valve, respectively. and These represent the second-stage opening of the throttle valve and the second-stage opening of the exhaust brake butterfly valve, respectively. The timer starts when the vehicle shutdown requirement is detected. The timer starts when fuel injection stops.

[0037] Both the engine start-up completion signal and the idle speed status flag are generated by the engine electronic control unit's (ECU) operational status management logic. When the engine start-up is complete and the idle speed status flag is valid, the vibration and noise optimization control mode and the exhaust temperature management mode are activated. When the engine leaves the idle state, these two modes are deactivated, and the throttle body and exhaust brake butterfly valve are taken over by the engine's normal operation control logic. The vehicle shutdown requirement is determined by the vehicle key off signal. After the vehicle key off signal is transmitted to the ECU, the ECU latches the shutdown requirement and initiates step S3. By switching modes through the operational status flag and the vehicle key signal, idle speed control and shutdown control can be executed in their respective engine states, preventing accidental triggering of corresponding controls during normal vehicle operation.

[0038] The engine electronic control unit (ECU) pre-stores a calibration relationship between coolant temperature and target idle speed. This calibration relationship consists of multiple coolant temperature calibration points and their corresponding idle speed calibration values. When the current coolant temperature... Located at adjacent coolant temperature calibration point and When the temperature interpolation weights are between, the interpolation weights are: The target idle speed is calculated according to the formula. Calculation. In the formula, This indicates the target idle speed corresponding to the current coolant temperature. Indicates the coolant temperature calibration point The corresponding idle speed calibration value, Indicates the coolant temperature calibration point The corresponding idle speed calibration value, Indicates the sequential index of the coolant temperature calibration point. This always represents the temperature interpolation weight between adjacent coolant temperature calibration points. When the current coolant temperature equals a calibration point, the idle speed calibration value corresponding to that calibration point is directly used; when the current coolant temperature exceeds the calibration range, the boundary calibration value closest to the current coolant temperature is used. The idle speed corresponding to -20 degrees Celsius is 800 rpm, and the idle speed corresponding to 0 degrees Celsius is 750 rpm. When the current coolant temperature is -10 degrees Celsius, the calculated target idle speed is 775 rpm.

[0039] The engine electronic control unit stores calibration tables for vibration and noise throttle opening and exhaust brake butterfly valve opening. Each calibration table uses coolant temperature as one coordinate dimension and engine speed as another, with the corresponding valve opening as the calibration value. Current engine speed... Located at adjacent speed calibration points and When the speed interpolation weight is between, the speed interpolation weight is .in, This indicates the sequential index of the engine speed calibration point. Always represents the speed interpolation weight between adjacent speed calibration points for the current engine speed.

[0040] This implementation uses bilinear interpolation with four adjacent calibration values. For any two-dimensional aperture calibration table Its interpolation operation is . In the formula, This represents a two-dimensional interpolation operation. This table represents the aperture calibration table used for interpolation. Indicates the coolant temperature calibration point and engine speed calibration point The corresponding aperture calibration value, , and These represent the throttle opening calibration values ​​corresponding to the other three adjacent calibration points. The candidate throttle opening for vibration and noise is determined according to... Calculation, vibration Dynamic noise exhaust brake butterfly valve candidate opening degree according to Calculation. Among them, A table showing throttle opening calibration for vibration and noise levels. A calibration table for the opening degree of the exhaust brake butterfly valve, indicating vibration and noise levels. Indicates the candidate throttle opening for vibration and noise. Indicates the candidate opening degree of the vibration and noise exhaust brake butterfly valve, subscript It always indicates the need for vibration and noise optimization.

[0041] During calibration, the engine is mounted on a test bench and kept running stably at different engine speed and coolant temperature calibration points. The combination of throttle opening and exhaust brake butterfly valve opening is adjusted sequentially. After each adjustment, the engine speed, coolant temperature, and opening feedback are allowed to stabilize before vibration and noise data are collected from the engine or cab measuring points. Vibration data is collected by vibration sensors, and noise data is collected by acoustic acquisition devices. The collected results are compared with the pre-determined vibration and noise limits for the corresponding engine model. The opening combinations that simultaneously meet the vibration and noise limits are saved, and vibration and noise throttle opening calibration tables and vibration and noise exhaust brake butterfly valve opening calibration tables are generated. Since both throttle opening and exhaust brake butterfly valve opening change the engine's intake and exhaust states and combustion states, the calibration focuses on the combination of the two openings as the evaluation object, rather than calibrating the two valves separately, thus reflecting the interactive influence of the two valves on engine vibration and noise.

[0042] The engine electronic control unit stores the thermal management throttle opening calibration table. and thermal management exhaust brake Butterfly valve opening calibration table Both calibration tables take coolant temperature and engine speed as inputs and output the valve opening required to meet exhaust temperature management. The thermal management throttle valve candidate opening is determined according to... count Calculate the candidate opening degree of the thermal management exhaust brake butterfly valve according to Calculation. Among them, Indicates the candidate opening degree of the thermal management throttle valve. Indicates the candidate opening degree of the thermal management exhaust brake butterfly valve, subscript It always indicates the exhaust temperature management requirements. By adjusting the opening of two valves, the engine intake air volume, exhaust back pressure, and combustion state are changed, so that the engine operates according to the exhaust temperature management requirements of the corresponding model during the idling stage after starting.

[0043] The engine electronic control unit compares the vibration, noise, and candidate throttle opening values ​​respectively. With thermal management throttle valve candidate opening and in accordance with Determine the target throttle opening; compare the candidate openings of the vibration, noise, exhaust, and brake butterfly valves. With thermal management exhaust brake butterfly valve candidate opening and in accordance with Determine the target opening degree of the exhaust brake butterfly valve. In the formula, This indicates the final target throttle opening. This indicates the target opening degree of the exhaust brake butterfly valve at the final output. This indicates that the smaller value is selected from two candidate opening values. All opening calibration tables use a unified opening direction; a smaller opening value indicates a smaller effective flow area of ​​the valve. The engine electronic control unit will... and The signals are sent to the throttle actuator and the exhaust brake butterfly valve actuator respectively, so that the two actuators reach the corresponding target opening degree.

[0044] When the engine electronic control unit detects a vehicle shutdown requirement, it reads the current engine speed. The throttle opening calibration table for the first stage of engine shutdown and the exhaust brake butterfly valve opening calibration table for the first stage of engine shutdown are used to determine the throttle opening. and .when Located at adjacent speed calibration points and When in between, the rotational speed interpolation weight is still used. The first stage of throttle opening is according to Calculations show that the first-stage opening degree of the exhaust brake butterfly valve is based on... Calculation. In the formula, and These represent the throttle opening calibration values ​​for the first stage corresponding to adjacent speed calibration points. and These represent the first-stage opening calibration values ​​of the exhaust brake butterfly valve corresponding to adjacent speed calibration points. First duration. Calibration is performed based on the engine speed variation, vibration status, and valve response characteristics of the corresponding engine model. Inside, the engine electronic control unit controls two valves to reduce their opening from the level before the shutdown request occurred to... and The process involves first limiting intake and exhaust flow and engine combustion, and then stopping fuel injection.

[0045] When the first duration At the end, the engine electronic control unit immediately sends a command to the fuel injection system to stop fuel injection, and then maintains the stopped fuel injection state throughout the remaining shutdown process. During the second duration after fuel injection stops... Inside, the throttle body and exhaust brake butterfly valve maintain the controlled state established in the first stage of control; when At the end, further reduce the throttle to And further reduce the exhaust brake butterfly valve to . This refers to the minimum controllable opening that the throttle body can stably reach and maintain according to the opening command. To ensure the exhaust brake butterfly valve can stably reach and maintain the minimum controllable opening degree according to the opening command, the minimum controllable opening degree does not necessarily have to be equal to the mechanically fully closed position. Second duration The calibration was performed based on the engine's shutdown speed decay process and speed fluctuations after fuel injection ceased, and compared with the first duration. Stored separately. The engine electronic control unit continuously collects engine speed data. ,exist Maintain when greater than zero , and the state of stopping fuel injection, in When the temperature drops to zero, the engine is determined to stop running and the shutdown control process ends.

[0046] The device includes an engine electronic control unit (ECU), a throttle valve and its actuator, an exhaust brake butterfly valve and its actuator, a coolant temperature sensor, an engine speed sensor, and a fuel injection system. The throttle valve is located in the engine intake passage and is used to change the intake airflow area based on the action of the throttle valve actuator. The exhaust brake butterfly valve is located in the engine exhaust passage and is used to change the exhaust airflow area and exhaust back pressure based on the action of the exhaust brake butterfly valve actuator. The coolant temperature sensor sends the coolant temperature to the ECU. The engine speed sensor sends the engine speed to the engine electronic control unit. The engine operation status management unit provides engine status information to the engine electronic control unit (ECU), while the vehicle key provides the ECU with the vehicle shutdown request. The ECU internally stores idle speed calibration relationships, vibration and noise opening calibration tables, thermal management opening calibration tables, and shutdown first-stage opening calibration tables. , , and Based on the stored data, the system performs opening interpolation, candidate opening comparison, valve control, and fuel injection shutdown control. The throttle actuator, exhaust brake butterfly valve actuator, and fuel injection system are all electrically connected to the engine electronic control unit, thus forming a closed-loop control device capable of actual operation, which integrates engine status acquisition, opening calculation, actuator action, and engine shutdown fuel cut-off.

[0047] Example 3 To further illustrate with reference to Example 1, this example focuses on a vehicle engine equipped with an electronic throttle and an exhaust brake butterfly valve. For example... Figure 1 As shown, the throttle valve is located in the engine intake passage, and the exhaust brake butterfly valve is located in the engine exhaust passage. The throttle valve actuator, exhaust brake butterfly valve actuator, coolant temperature sensor, engine speed sensor, fuel injection system, and vehicle key signal terminal are all connected to the engine electronic control unit (ECU). The coolant temperature sensor is used to collect the current coolant temperature, the engine speed sensor is used to collect the current engine speed, and the vehicle key signal terminal is used to send a vehicle shutdown request to the ECU. The ECU controls the throttle opening, exhaust brake butterfly valve opening, and fuel injection status based on the collected data.

[0048] This embodiment is uniformly based on Indicates the current coolant temperature, in Indicates the current engine speed, in The class symbol represents the throttle opening, in order to The symbol represents the opening degree of the exhaust brake butterfly valve. Both the throttle opening degree and the exhaust brake butterfly valve opening degree are calibrated according to the principle that the smaller the opening value, the smaller the effective flow area. The engine electronic control unit pre-stores calibration relationships between coolant temperature and target idle speed, vibration and noise throttle opening degree calibration tables, vibration and noise exhaust brake butterfly valve opening degree calibration tables, thermal management throttle opening degree calibration tables, thermal management exhaust brake butterfly valve opening degree calibration tables, throttle opening degree calibration tables for the first stage of engine shutdown, and exhaust brake butterfly valve opening degree calibration tables for the first stage of engine shutdown.

[0049] like Figure 7As shown, when establishing the vibration and noise opening calibration table, the engine was installed on the test bench and operated stably at different engine speed calibration points and coolant temperature calibration points. The combination of throttle opening and exhaust brake butterfly valve opening was changed in sequence, and the corresponding vibration and noise data were collected. Figure 7 x-coordinate in The vertical axis represents the throttle opening. This indicates the opening degree of the exhaust brake butterfly valve; the circular dots represent the opening degree combinations that were tested. , and This represents the contour lines representing different vibration and noise evaluation levels based on the test results. This represents the boundary that meets the vibration and noise control requirements. This represents the target combination determined from the opening combinations that meet the control requirements. By repeating the above calibration process at each engine speed calibration point and coolant temperature calibration point, a vibration and noise throttle opening calibration table and a vibration and noise exhaust brake butterfly valve opening calibration table are generated.

[0050] The thermal management throttle opening calibration table and the thermal management exhaust brake butterfly valve opening calibration table were obtained through engine bench calibration. Under different engine speeds and coolant temperatures, the openings of the throttle and exhaust brake butterfly valves were adjusted, and changes in engine exhaust temperature were monitored. The opening combinations that meet the exhaust temperature management requirements of the corresponding engine model were then recorded in the relevant calibration tables. This calibration process considers the combined effects of the throttle and exhaust brake butterfly valves on intake air volume, exhaust back pressure, and combustion state.

[0051] Engine start-stop control process according to Figure 4 The process shown is executed. In step S1, the engine electronic control unit periodically acquires the engine status and current engine speed. Current coolant temperature Idle status indicator and vehicle key signal. When the engine starts and the idle status indicator is valid, it is determined that the engine is in the start-up idle state and proceeds to step S2; if the engine is not in the start-up idle state, it continues to determine whether there is a need to shut down the entire vehicle; when the vehicle key off signal is valid, it is determined that there is a need to shut down the entire vehicle and proceeds to step S3.

[0052] Step S2 according to Figure 2 The idle speed control strategy shown is executed. When the engine has started and is idling, the engine electronic control unit activates the vibration and noise optimization control mode and the exhaust temperature management mode. First, the target idle speed is determined based on the calibration relationship between coolant temperature and target idle speed. When the current coolant temperature... Located at adjacent coolant temperature calibration point and When in between, the temperature interpolation weights are based on Calculation, target idle speed according to calculate.

[0053] In the formula, and These represent the coolant temperature calibration points on both sides of the current coolant temperature. Indicates the sequential index of the coolant temperature calibration point. Indicates the temperature interpolation weights. Indicates the target idle speed. and These represent the idle speed calibration values ​​corresponding to two adjacent coolant temperature calibration points. The idle speed at -20 degrees Celsius is 800 rpm, and at 0 degrees Celsius it is 750 rpm. When the current coolant temperature is -10 degrees Celsius, the calculated target idle speed is 775 rpm.

[0054] After determining the target idle speed, the engine electronic control unit performs two-dimensional interpolation based on the current engine speed and current coolant temperature. When the current engine speed... Located at adjacent engine speed calibration point and When the speed interpolation weights are in between, they are calculated according to... Calculation. Among them, This indicates the sequential index of the engine speed calibration point. This indicates the interpolation weight for rotational speed.

[0055] For any two-dimensional aperture calibration table The two-dimensional interpolation results are based on Calculation. In the formula, This represents a two-dimensional interpolation operation. This table represents the aperture calibration table used for interpolation. Indicates the coolant temperature calibration point and engine speed calibration point The corresponding opening calibration value, and the other three calibration values ​​are the other three opening calibration values ​​formed by adjacent temperature calibration points and adjacent speed calibration points.

[0056] like Figure 5 As shown, the candidate throttle opening for vibration and noise is determined according to... Calculation of vibration noise Candidate opening degree of exhaust brake butterfly valve according to Calculation. The candidate opening of the thermal management throttle valve is calculated according to... Calculations are made based on the candidate opening degree of the thermal management exhaust brake butterfly valve. calculate.

[0057] in, A table showing throttle opening calibration for vibration and noise levels. A calibration table for the opening degree of the exhaust brake butterfly valve, indicating vibration and noise levels. This table represents the throttle opening calibration for thermal management. This table displays the opening calibration of the thermal management exhaust brake butterfly valve. (Subscript) Always indicating the need for vibration and noise optimization, subscript It always indicates the need for exhaust temperature management.

[0058] Engine electronic control unit according to Determine the target throttle opening and follow... Determine the target opening degree of the exhaust brake butterfly valve. Among other things, Indicates the target throttle opening. Indicates the target opening degree of the exhaust brake butterfly valve. This indicates that the smaller of the two candidate opening values ​​is selected.

[0059] Taking a current coolant temperature of -10 degrees Celsius and an engine speed of 775 rpm as an example, after interpolation based on calibration data, the candidate opening values ​​for both the vibration and noise throttle valve and the exhaust brake butterfly valve are 30%, while the candidate opening values ​​for both the thermal management throttle valve and the thermal management exhaust brake butterfly valve are 40%. Therefore, the target opening values ​​for both the throttle valve and the exhaust brake butterfly valve are determined to be 30%. The engine electronic control unit sends the corresponding opening commands to the two actuators. When the engine leaves idle, the vibration and noise optimization control mode and the exhaust temperature management mode are exited.

[0060] Step S3 according to Figure 3 The shutdown control strategy is executed as shown. After the vehicle key is turned off, the engine electronic control unit latches the vehicle shutdown request and enters the first stage of control. At the start of the first stage of control, the current engine speed is read, and the throttle opening for the first stage is determined according to the shutdown first stage opening calibration table. and the first stage opening of the exhaust brake butterfly valve .

[0061] When the current engine speed is at and During this period, the first stage of throttle opening is as follows: Calculations show that the first-stage opening degree of the exhaust brake butterfly valve is based on... Calculation. Among them, and This indicates the throttle opening calibration value for the first stage corresponding to adjacent engine speed calibration points. and This indicates the first-stage opening calibration value of the exhaust brake butterfly valve corresponding to adjacent engine speed calibration points.

[0062] Taking an engine speed of 675 rpm when a shutdown requirement occurs as an example, based on the calibration data that 650 rpm corresponds to 25% opening and 700 rpm corresponds to 30% opening, interpolation calculations are performed to obtain... and Both are 27.5%. The engine electronic control unit (ECU) is in the first time... The throttle body and exhaust brake butterfly valve are reduced to [size missing]. and First duration Pre-calibrate based on the valve response characteristics, speed changes, and shutdown vibration of the corresponding engine model.

[0063] like Figure 6 As shown, when the first duration When the process ends, the engine electronic control unit immediately sends a command to the fuel injection system to stop fuel injection. Figure 6 In Indicates the fuel injection status. This indicates that fuel injection is permitted. This indicates that fuel injection has stopped. After fuel injection stops, the throttle body and exhaust brake butterfly valve remain in the first stage of controlled state, and the second duration calculation begins. .

[0064] When fuel injection stops for the second duration Then, the engine electronic control unit further reduces the throttle opening to the second stage. The exhaust brake butterfly valve will be further reduced to the second stage opening. . This refers to the minimum controllable opening that the throttle body can stably reach and maintain. This is the minimum controllable opening degree that the exhaust brake butterfly valve can stably reach and maintain. Second duration. Pre-calibrated based on the engine speed decay process and speed fluctuation after fuel injection stops.

[0065] In the second stage, the engine electronic control unit continuously collects and maintains the engine speed. , and The control status. Engine speed. If the value is greater than zero, continue to execute the second stage of control, engine speed When the speed drops to zero, the engine is determined to have stopped running, ending the shutdown control process. Thus, through the phased coordination of the throttle body, exhaust brake butterfly valve, and fuel injection system, the engine gradually transitions from idling combustion to a shut-off state, reducing speed fluctuations, vibrations, and noise during the shutdown process.

[0066] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. An engine start-stop control method, characterized in that: The electronic control unit performs the following steps: S1. Obtain engine operating status, engine speed and coolant temperature, and identify the idling condition and shutdown requirements after engine start-up based on the engine operating status. S2. When the engine is in the idling condition after starting, the target opening of the throttle valve and the target opening of the exhaust brake butterfly valve are determined according to the engine speed and coolant temperature, and the throttle valve and the exhaust brake butterfly valve are controlled to reach the corresponding target openings respectively. S3. When a shutdown request is detected, the throttle valve and exhaust brake butterfly valve are reduced to their corresponding first-stage openings within the first duration. After the first duration ends, the fuel injection device is controlled to stop injecting fuel. After the fuel injection stops for the second duration, the throttle valve and exhaust brake butterfly valve are further reduced to their corresponding second-stage openings, and the fuel injection is kept stopped until the engine speed drops to zero.

2. The engine start-stop control method according to claim 1, characterized in that: In step S1, when the electronic control unit detects both the engine start completion signal and the idle mode indicator, it activates vibration and noise optimization control and exhaust temperature management control; when the engine exits idle mode, it exits vibration and noise optimization control and exhaust temperature management control. The electronic control unit identifies shutdown requirements based on the received vehicle power failure and shutdown signal.

3. The engine start-stop control method according to claim 1, characterized in that: In step S2, the target idle speed is obtained by interpolation calculation based on the coolant temperature in the preset coolant temperature and idle speed calibration relationship, and the engine idle speed is controlled according to the target idle speed.

4. The engine start-stop control method according to claim 1, characterized in that: In step S2, based on the engine speed and coolant temperature, interpolation calculation is performed in the preset vibration and noise control throttle opening mapping relationship to obtain the vibration and noise control throttle opening; based on the engine speed and coolant temperature, interpolation calculation is performed in the preset vibration and noise control exhaust brake butterfly valve opening mapping relationship to obtain the vibration and noise control exhaust brake butterfly valve opening.

5. The engine start-stop control method according to claim 4, characterized in that: The mapping relationship between throttle opening for vibration and noise control and the mapping relationship between exhaust brake butterfly valve opening for vibration and noise control are established in the following way: Multiple engine speed and coolant temperature combinations are set on the engine test bench. The throttle opening and exhaust brake butterfly valve opening are adjusted under each combination. Corresponding engine vibration and noise data are collected. The opening combinations that do not exceed the preset vibration limit and the noise limit are determined. The corresponding opening combinations are stored according to the engine speed and coolant temperature.

6. The engine start-stop control method according to claim 4, characterized in that: In step S2, the throttle opening for exhaust temperature management is obtained by interpolation calculation based on the engine speed and coolant temperature in a preset mapping relationship of exhaust temperature management; the exhaust brake butterfly valve opening for exhaust temperature management is also obtained by interpolation calculation based on the engine speed and coolant temperature in a preset mapping relationship of exhaust temperature management.

7. The engine start-stop control method according to claim 6, characterized in that: Step S2 In this study, the smaller value between the throttle opening for vibration and noise control and the throttle opening for exhaust temperature management is determined as the target throttle opening; the smaller value between the exhaust brake butterfly valve opening for vibration and noise control and the exhaust brake butterfly valve opening for exhaust temperature management is determined as the target exhaust brake butterfly valve opening.

8. The engine start-stop control method according to claim 1, characterized in that: In step S3, based on the engine speed when the shutdown requirement is identified, interpolation calculations are performed in the preset throttle opening mapping relationship and the exhaust brake butterfly valve opening mapping relationship for the first stage of shutdown to obtain the throttle opening and the exhaust brake butterfly valve opening for the first stage. Within the first duration, the throttle valve is reduced to the first stage throttle valve opening, and the exhaust brake butterfly valve is reduced to the first stage exhaust brake butterfly valve opening; the first duration is pre-calibrated according to the characteristics of the engine model.

9. The engine start-stop control method according to claim 8, characterized in that: In step S3, at the end of the first duration, the fuel injection device is immediately controlled to stop injecting fuel and maintain the stopped fuel injection state; after the fuel injection stops for the second duration, the throttle valve is controlled to the minimum controllable opening of the corresponding engine model, and the exhaust brake butterfly valve is controlled to the minimum controllable opening of the corresponding engine model, until the engine speed drops to zero; the second duration is pre-calibrated according to the characteristics of the engine model.

10. An engine start-stop control device, characterized in that: This includes an electronic control unit, throttle valve, throttle valve actuator, exhaust brake butterfly valve, exhaust brake butterfly valve actuator, coolant temperature sensor, and fuel injection device; The throttle valve is located in the engine intake passage, and the throttle valve actuator is used to adjust the throttle valve opening. The exhaust brake butterfly valve is located in the engine exhaust passage, and the exhaust brake butterfly valve actuator is used to adjust the exhaust brake butterfly valve opening. The electronic control unit has signal input terminals for receiving engine operating status, engine speed, coolant temperature and shutdown requirements. The control output terminals of the electronic control unit are respectively connected to the throttle actuator, exhaust brake butterfly valve actuator and fuel injection device. The electronic control unit is used to control the throttle opening and the exhaust brake butterfly valve opening based on the engine speed and coolant temperature when the engine is idling after starting. It is also used to, after recognizing a shutdown requirement, sequentially control the throttle and exhaust brake butterfly valve to reach the first stage opening, control the fuel injection device to stop injecting fuel, and control the throttle and exhaust brake butterfly valve to reach the second stage opening, until the engine speed drops to zero.

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