Engine start control method, device, vehicle and medium

Abstract

Embodiments of the present application provide an engine starting control method, device, vehicle and medium. The method comprises: in response to an engine starting request of a vehicle, determining a starting mode of the engine based on an initial coolant temperature when the engine receives the starting request; controlling a drive motor of the vehicle to output a drag torque to the engine according to a current target speed, so that an actual speed of the engine approaches the target speed; and controlling the engine to perform fuel injection ignition according to the starting mode, the actual speed and the target speed, so as to start the engine. The method is used to improve the adaptability of the original engine starting process to variable working conditions and the overall smoothness.

Description

Technical Field

[0001] This application relates to the field of vehicle control, and more particularly to an engine start control method, device, vehicle, and medium. Background Technology

[0002] During the startup process of a hybrid vehicle, the engine's noise, vibration, and harshness (NVH) performance are key factors affecting ride comfort.

[0003] Currently, the starting process typically requires the drive motor to first apply drag torque to the engine, causing the engine speed to rise to the target speed, and then triggering the engine side to perform fuel injection and ignition to complete the starting process.

[0004] However, under different temperature conditions, the mechanical resistance and speed stability of the engine vary. The existing technology with its single and fixed ignition triggering timing is difficult to adapt to the changing starting conditions, resulting in poor NVH performance of the engine during the starting phase.

[0005] Therefore, a new control technology is urgently needed to improve the engine's adaptability to changing operating conditions and overall smoothness during the original engine start-up process. Summary of the Invention

[0006] This application provides an engine starting control method, device, vehicle, and medium to improve the engine's adaptability to changing operating conditions and overall smoothness during the original engine starting process.

[0007] In a first aspect, embodiments of this application provide an engine start-up control method, including:

[0008] In response to a vehicle's engine start request, the engine start mode is determined based on the initial coolant temperature of the engine when the start request is received.

[0009] The vehicle's drive motor is controlled in real time to output traction torque to the engine according to the current target speed, so that the actual speed of the engine approaches the target speed;

[0010] Based on the starting mode, the actual speed, and the target speed, the engine is controlled to perform fuel injection and ignition to start the engine.

[0011] In one possible embodiment, controlling the engine to perform fuel injection and ignition to start the engine based on the starting mode, the actual speed, and the target speed includes:

[0012] If the starting mode is a cold start mode, then when the time for which the difference between the actual speed and the target speed is within the target allowable difference range reaches a preset duration, the engine is controlled to inject fuel and ignite. The target allowable difference range is determined based on the engine coolant temperature.

[0013] If the starting mode is a warm-up start mode, then when the actual speed reaches the target speed, the engine is controlled to inject fuel and ignite.

[0014] In one possible embodiment, the method further includes:

[0015] The current target speed of the engine is determined based on the current coolant temperature of the engine.

[0016] In one possible embodiment, determining the current target engine speed based on the current coolant temperature of the engine includes:

[0017] When the starting mode is cold start mode, the current target speed of the engine is determined based on the current maximum discharge capacity of the vehicle's power battery and the current coolant temperature of the engine; or,

[0018] When the starting mode is the hot engine start mode, the current target speed of the engine is determined according to the current coolant temperature of the engine and a preset first mapping relationship; the first mapping relationship is the mapping relationship between coolant temperature and target speed.

[0019] In one possible embodiment, the real-time control of the vehicle's drive motor to output drag torque to the engine according to the current target speed includes:

[0020] The difference between the actual rotational speed and the target rotational speed is obtained in real time;

[0021] Based on the difference, determine the current drag torque;

[0022] The drive motor is controlled to apply the drag torque to the engine.

[0023] In one possible embodiment, determining the current drag torque based on the difference includes:

[0024] The current drag torque is determined based on the difference, the current coolant temperature of the engine, and a preset second mapping relationship;

[0025] The second mapping relationship is the mapping relationship between the difference, the driving torque and the coolant temperature, wherein the difference and the driving torque, and the coolant temperature and the driving torque are both negatively correlated.

[0026] In one possible embodiment, determining the engine start mode based on the initial coolant temperature when the engine receives the start request includes:

[0027] Obtain the initial coolant temperature and initial catalyst temperature of the engine when it receives the start request;

[0028] When the initial coolant temperature is greater than the first preset threshold and the initial catalyst temperature is greater than the second preset threshold, the engine start mode is determined to be the warm engine start mode; otherwise, the engine start mode is determined to be the cold engine start mode.

[0029] In one possible embodiment, the method further includes:

[0030] After successful fuel injection and ignition, the output torque of the drive motor is adjusted from the drag torque to the generator torque.

[0031] The slope of the output torque change in the zero-value region is used to drive the output torque to quickly pass through the zero-value region along a single trend.

[0032] Secondly, embodiments of this application provide an engine start control device, comprising:

[0033] The first determining module is used to determine the engine start mode based on the initial coolant temperature of the engine when the engine receives the start request in response to the vehicle's engine start request.

[0034] The first control module is used to control the vehicle's drive motor to output drag torque to the engine according to the current target speed in real time, so that the actual speed of the engine approaches the target speed.

[0035] The second control module is used to control the engine to perform fuel injection and ignition according to the starting mode, the actual speed and the target speed, so as to start the engine.

[0036] In one possible embodiment, the second control module is configured to:

[0037] If the starting mode is a cold start mode, then when the time for which the difference between the actual speed and the target speed is within the target allowable difference range reaches a preset duration, the engine is controlled to inject fuel and ignite. The target allowable difference range is determined based on the engine coolant temperature.

[0038] If the starting mode is a warm-up start mode, then when the actual speed reaches the target speed, the engine is controlled to inject fuel and ignite.

[0039] In one possible embodiment, the device further includes:

[0040] The second determining module is used to determine the current target speed of the engine in real time based on the current coolant temperature of the engine.

[0041] In one possible embodiment, the second determining module is specifically used for:

[0042] When the starting mode is cold start mode, the current target speed of the engine is determined based on the current maximum discharge capacity of the vehicle's power battery and the current coolant temperature of the engine; or,

[0043] When the starting mode is the hot engine start mode, the current target speed of the engine is determined according to the current coolant temperature of the engine and a preset first mapping relationship; the first mapping relationship is the mapping relationship between coolant temperature and target speed.

[0044] In one possible embodiment, the first control module includes:

[0045] The acquisition unit is used to acquire the difference between the actual rotational speed and the target rotational speed in real time;

[0046] The determining unit is used to determine the current driving torque based on the difference;

[0047] A control unit is used to control the drive motor to apply the drag torque to the engine.

[0048] In one possible embodiment, the determining unit is specifically used for:

[0049] The current drag torque is determined based on the difference, the current coolant temperature of the engine, and a preset second mapping relationship;

[0050] The second mapping relationship is the mapping relationship between the difference, the driving torque and the coolant temperature, wherein the difference and the driving torque, and the coolant temperature and the driving torque are both negatively correlated.

[0051] In one possible embodiment, the first determining module is specifically used for:

[0052] Obtain the initial coolant temperature and initial catalyst temperature of the engine when it receives the start request;

[0053] When the initial coolant temperature is greater than the first preset threshold and the initial catalyst temperature is greater than the second preset threshold, the engine start mode is determined to be the warm engine start mode; otherwise, the engine start mode is determined to be the cold engine start mode.

[0054] In one possible embodiment, the device further includes a third control module for:

[0055] After successful fuel injection and ignition, the output torque of the drive motor is adjusted from the drag torque to the generator torque.

[0056] The slope of the output torque change in the zero-value region is used to drive the output torque to quickly pass through the zero-value region along a single trend.

[0057] Thirdly, embodiments of this application provide a controller, including: a memory and a processor;

[0058] The memory stores instructions that the computer executes;

[0059] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0060] Fourthly, embodiments of this application provide a vehicle, which includes a vehicle body and the controller provided above.

[0061] Fifthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0062] In a sixth aspect, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0063] The engine start control method, device, vehicle, and medium provided in this application embodiment, in response to the vehicle's engine start request, determine the engine start mode based on the initial coolant temperature when the engine receives the start request, and control the drive motor to output drag torque to the engine according to the current target speed in real time. Furthermore, the engine is controlled to perform fuel injection and ignition according to the start mode, the actual engine speed, and the target speed to start the engine. This enables the engine start control to better adapt to actual temperature conditions, improve the accuracy of engine ignition timing, and thus achieve the effect of improving engine start smoothness and overall vehicle NVH performance. Attached Figure Description

[0064] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0065] Figure 1This is a flowchart illustrating an engine start-up control method provided in Embodiment 1 of this application;

[0066] Figure 2 This is a flowchart illustrating an engine start-up control method provided in Embodiment 2 of this application;

[0067] Figure 3 This is a flowchart illustrating an engine start-up control method provided in Embodiment 3 of this application;

[0068] Figure 4 This is a schematic diagram of the structure of an engine start control device provided in Embodiment 4 of this application;

[0069] Figure 5 This is a schematic diagram of the structure of an engine start control device provided in Embodiment 5 of this application;

[0070] Figure 6 This is a schematic diagram of the structure of a controller provided in Embodiment Six of this application.

[0071] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0072] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0073] To facilitate understanding of the technical content of this application, the background technology is described in detail below:

[0074] Hybrid electric vehicles (HEVs) are vehicles that simultaneously possess an engine and an electric drive system. Due to their excellent fuel economy and low emissions, they have become an important development direction for the automotive industry. With the popularization of technology and the increasing demands of consumers for better experiences, the focus of vehicle performance optimization has expanded from single indicators such as energy consumption and range to a comprehensive evaluation system encompassing driving quality. Among these, the noise, vibration, and harshness (NVH) performance during engine start-stop, especially the impact and knocking sensations that may occur at the moment of startup, are key factors affecting ride comfort and directly related to user perception of product quality.

[0075] Currently, starting typically requires a drive motor (i.e., the P1 motor, a generator-starter located at the crankshaft end of the engine) to first apply torque to the engine, causing the engine speed to rise to the target speed. Then, the engine side is triggered to perform fuel injection and ignition to complete the starting process. However, under different temperature conditions, the engine's mechanical resistance and speed stability vary. The existing technology's single, fixed ignition timing is difficult to adapt to the changing starting conditions, resulting in poor NVH performance during the engine's start-up phase.

[0076] To address this technical problem, the inventors discovered during their research that, upon triggering an engine start request, the engine start mode can be first determined based on the initial coolant temperature at the time the start request is received. Then, when the drive motor applies torque to the engine, the strategy is determined based on the actual engine speed and target speed reflecting the actual engine operation and combustion conditions, as well as the ignition timing indicated by the start mode. This allows for precise control of engine fuel injection and ignition, enabling the engine start control to better adapt to actual operating conditions, improving the accuracy of engine ignition timing, and ultimately enhancing engine start smoothness and overall vehicle NVH performance. Therefore, this application proposes an engine start control method, device, vehicle, and medium.

[0077] It should be noted that the method provided in this application embodiment can be executed in the vehicle controller, such as the vehicle control unit (HCU) or motor control unit (MCU), and this application does not impose specific restrictions on the subject executing the method.

[0078] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0079] Figure 1 This is a flowchart illustrating an engine start-up control method provided in Embodiment 1 of this application, as shown below. Figure 1 As shown, the method includes:

[0080] S101: In response to the vehicle's engine start request, determine the engine start mode based on the initial coolant temperature when the engine receives the start request.

[0081] In this step, the controller will obtain the initial coolant temperature of the engine when the request is received, and determine the current engine start mode based on the initial coolant temperature, triggered by the vehicle's engine start request.

[0082] Among them, the engine start request refers to the demand signal that triggers the engine to enter the start process from a stationary or low-speed standby state. This request can be generated by the controller based on the vehicle's power demand, air conditioning load demand, battery charge status, driver acceleration intention and other vehicle operating conditions; the coolant temperature represents the thermal state of the engine body, which is usually collected by a temperature sensor set in the engine coolant circuit and received periodically by the controller.

[0083] Considering the differences in engine mechanical resistance, speed stability, and fuel atomization under different temperature conditions, different fuel injection ignition timing judgment mechanisms are preset based on engine temperature conditions for different starting modes. Starting modes include, for example, cold engine start mode and warm engine start mode. The cold engine start mode can be further subdivided into deep cold engine start mode and normal temperature cold engine start mode.

[0084] In one possible implementation, upon triggering an engine start request, the current coolant temperature (i.e., the initial coolant temperature) of the engine can be obtained, and the current engine start mode can be determined based on the temperature range within which the initial coolant temperature falls. For example, when the initial coolant temperature is greater than a first preset threshold, it is determined to be a cold start mode; when the initial coolant temperature is less than or equal to the first preset threshold, it is determined to be a warm start mode.

[0085] In another possible implementation, to further improve the accuracy of starting mode identification, the current starting mode of the vehicle can be determined in conjunction with the temperature of the catalytic converter, specifically including the following steps a to b:

[0086] Step a: Obtain the initial coolant temperature and initial catalyst temperature of the engine when it receives the start request.

[0087] The catalyst temperature refers to the temperature of the three-way catalytic converter integrated into the engine exhaust system. It characterizes the temperature of the engine's downstream exhaust system and can be obtained by a temperature sensor located near the catalyst housing, or estimated by the controller based on exhaust temperature, engine running time, or a thermal model.

[0088] Step b: When the initial coolant temperature is greater than the first preset threshold and the initial catalyst temperature is greater than the second preset threshold, determine that the engine start mode is the warm engine start mode; otherwise, determine that the engine start mode is the cold engine start mode.

[0089] In detail, when the initial coolant temperature is greater than the first preset threshold and the initial catalytic converter temperature is greater than the second preset threshold, it indicates that the engine and aftertreatment system are in a relatively warm state. During startup, this provides conditions for low mechanical friction and stable overall operation, thus qualifying as a warm-up start mode. If the initial coolant temperature is lower than the first preset threshold, it indicates that the engine itself is underheated. If the initial catalytic converter temperature is lower than the second preset threshold, it indicates that the three-way catalytic converter in the engine's exhaust system is underheated. Therefore, if either temperature fails to reach the corresponding threshold, it is considered a cold-up start mode.

[0090] The setting of the first preset threshold and the second preset threshold can be obtained by calibrating the engine oil viscosity and other performance parameters under different coolant temperatures and different catalyst temperatures. This application does not limit the setting of these specific values.

[0091] By simultaneously introducing the initial coolant temperature and the initial catalyst temperature for joint determination, misjudgment caused by relying on only a single temperature parameter can be avoided, effectively improving the accuracy of start-up mode recognition, and providing a reliable basis for subsequent towing torque control, target speed control, and fuel injection timing control, thereby improving the smoothness and success rate of engine start-up and the overall vehicle NVH performance.

[0092] S102: Real-time control of the vehicle's drive motor to output drag torque to the engine according to the current target speed, so that the actual speed of the engine approaches the target speed.

[0093] In this step, the controller will acquire the current target speed of the engine in real time, calculate the drag torque that needs to be applied to the engine based on the target speed, and send a control command carrying the drag torque to the drive motor so that the drive motor can apply the drag torque to the engine.

[0094] Understandably, after the engine applies driving torque, the driving torque will continuously overcome the internal frictional resistance, pumping resistance and accessory load resistance of the engine, and continuously output positive driving power to the crankshaft. The crankshaft rotational kinetic energy will continue to accumulate, and thus its actual speed will gradually approach the target speed.

[0095] Among them, the drive motor is a motor device that is mechanically coupled to the engine in the hybrid system. When the engine has not yet established its own combustion capability, it outputs positive drag torque to the engine to increase the crankshaft speed. After starting, the drive motor can also switch to the power generation mode to undertake energy recovery or power supply functions.

[0096] The target speed refers to the real-time reference speed that the engine needs to reach or approach during the start-up phase. It can be a fixed value determined directly by the controller based on the current operating conditions after receiving the engine start request, and it remains unchanged throughout the start-up process; or it can be a dynamic value that the vehicle dynamically determines based on the real-time operating conditions, and it changes adaptively with the operating conditions throughout the start-up process.

[0097] The actual engine speed is the real-time engine speed obtained from the crankshaft position sensor, speed sensor, or motor-side speed, and is used to reflect whether the engine is close to the speed condition required for ignition.

[0098] In one possible implementation, the current target engine speed can be determined based on the current coolant temperature of the engine.

[0099] It is understandable that coolant temperature directly determines engine oil viscosity and internal friction resistance. Therefore, setting the target speed according to the difference in coolant temperature can ensure starting efficiency when the coolant temperature is high and the friction resistance is low, and reduce the driving load and stabilize the operation when the coolant temperature is low and the friction resistance is high.

[0100] For example, when the engine coolant temperature is low, a lower target speed can be set to reduce system load; when the engine coolant temperature is high, a higher target speed can be set to facilitate rapid start-up.

[0101] As a concrete example, upon receiving an engine start request, the target engine speed can be set directly based on the engine's current coolant temperature (i.e., the initial coolant temperature), and this target speed can be maintained throughout the start-up process until the engine has started. This example provides a method that ensures low computational overhead during the engine start-up process.

[0102] As another concrete example, the target engine speed can be determined in real time based on the current coolant temperature throughout the entire startup phase before engine fuel injection and ignition. Alternatively, the target speed can be redefined at preset frequencies based on the current coolant temperature. The method provided in this example continuously adjusts the target speed according to the coolant temperature changes during startup, allowing the target speed to dynamically adapt to operating conditions, further optimizing the control accuracy of the entire startup process. Furthermore, the higher the frequency of target speed determination, the higher the control accuracy of the startup process.

[0103] It should be noted that this application does not limit the frequency of determining the target speed during the entire startup process. The specific implementation method of this step can be flexibly set according to the actual application requirements for control accuracy and computational overhead.

[0104] Based on the above analysis, it can be concluded that by setting the target speed during the startup phase according to the different coolant temperature conditions at actual startup, the scenario adaptability of the target speed can be improved, thereby achieving the effect of taking into account the differentiated operating requirements under various startup conditions.

[0105] S103: Controls the engine to perform fuel injection and ignition according to the starting mode, actual speed and target speed to start the engine.

[0106] In this step, the controller needs to determine in real time whether the engine has reached the fuel injection ignition timing indicated by the start-up mode based on the actual engine speed and the target speed. When the timing is reached, the controller needs to control the engine to inject fuel and ignite, so that the engine changes from a state of being simply driven by the motor to a state of autonomously outputting torque through combustion, thereby completing the engine start-up.

[0107] In practice, the controller can send a fuel injection and ignition command to the engine management system (EMS) so that the EMS controls the ignition actuators (such as fuel injectors) on the engine to perform fuel injection and ignition operations to ignite the combustible mixture in the engine cylinder.

[0108] Different settings for fuel injection ignition timing are used for different starting modes. For example, in cold engine mode, a more sufficient speed build-up and stricter stability judgment are required, while in hot engine mode, a faster ignition criterion can be used. This ensures that the ignition timing is adapted to the actual operating conditions in any starting mode: on the one hand, it effectively avoids incomplete combustion and unstable torque output caused by premature ignition when the engine is at low temperatures; on the other hand, it effectively avoids unnecessary energy consumption and noise caused by prolonged pure electric motor drive phase due to delayed ignition when the engine is at high temperatures.

[0109] The engine start control method, device, vehicle, and medium provided in this application, after receiving an engine start request, determine the engine start mode based on the initial coolant temperature of the engine, and control the drive motor to output drag torque to the engine according to the current target speed in real time. Furthermore, the engine is controlled to perform fuel injection and ignition according to the start mode, actual speed, and target speed to start the engine. This enables the engine start control to better adapt to actual temperature conditions, improves the accuracy of engine ignition timing, and thus enhances the smoothness of engine start and the NVH performance of the entire vehicle.

[0110] Furthermore, Figure 2 This is a flowchart illustrating an engine start-up control method provided in Embodiment 2 of this application, as shown below. Figure 2 As shown, based on the above embodiments, the method includes:

[0111] S201: In response to the vehicle's engine start request, determine that the engine start mode is cold start mode.

[0112] In this embodiment, the engine starting mode is determined to be a cold start mode based on the initial coolant temperature when the vehicle's transmitter receives the start request.

[0113] S202: Determine the current target engine speed based on the vehicle's current maximum discharge capacity of the power battery and the current engine coolant temperature.

[0114] In this step, the controller will obtain the current maximum discharge capacity of the vehicle's power battery and the current coolant temperature of the engine, and calculate the target speed that matches the maximum discharge capacity and coolant temperature based on the pre-established third mapping relationship.

[0115] Among them, the power battery is the energy supply battery in the vehicle. The maximum discharge capacity represents the maximum electrical energy support level that the battery can output under the current state, thereby reflecting the battery's support capacity for engine start-up. It can be collected by the controller through the battery management system.

[0116] Understandably, because the internal resistance of the engine is relatively large in cold start mode, and the battery output capacity may fluctuate with changes in state of charge and temperature, the maximum discharge capacity is further incorporated into the target speed determination process in addition to considering the engine coolant temperature, so that the target speed can be further adapted to the available driving capacity.

[0117] Specifically, in this third mapping relationship, the maximum discharge capacity is negatively correlated with the target speed, while the coolant temperature is positively correlated with the target speed. This can be used to determine the target speed corresponding to different maximum discharge capacities and coolant temperatures. The design aims to reduce system load by appropriately lowering the target speed when battery discharge capacity is limited and coolant temperature is low, while avoiding start-up failure due to insufficient battery discharge capacity. Conversely, when battery capacity is sufficient and coolant temperature is relatively high, a higher target speed can be set, enabling rapid engine start-up in scenarios with ample battery reserves, optimizing the vehicle's NVH performance, and ultimately improving the user experience.

[0118] In practical applications, this third mapping relationship can be established offline using calibration data, and can take the form of a two-dimensional calibration table, a function expression, or a piecewise function. For example, in the form of a two-dimensional calibration table, the horizontal axis corresponds to the maximum discharge capacity, the vertical axis corresponds to the target speed, and the table entries correspond to the speed values. As the maximum discharge capacity increases, the speed value corresponding to the table entry increases; as the coolant temperature increases, the speed value corresponding to the table entry also increases.

[0119] For example, the target speed can be determined globally uniquely during the start-up process only after the current start-up mode is determined to be a cold start, based on the initial maximum discharge capacity of the power battery and the initial coolant temperature of the engine when the start-up request is received, so as to ensure that the start-up process has low computational overhead; or, the target speed of the vehicle can be dynamically determined in real time or at a preset frequency based on the maximum discharge capacity and coolant temperature at each moment during the entire start-up phase before engine fuel injection and ignition, so as to ensure that the target speed can be adaptively adjusted according to real-time operating conditions.

[0120] Based on the above analysis, using this step to determine the target speed under cold start mode can achieve a balance between start-up reliability and the overall NVH performance of the vehicle.

[0121] S203: Real-time control of the drive motor to output drag torque to the engine according to the current target speed, so that the actual speed of the engine approaches the target speed.

[0122] In one possible implementation, this step may include steps 4.1 to 4.3 as follows:

[0123] Step 4.1: Obtain the difference between the actual rotational speed and the target rotational speed in real time.

[0124] In this step, the controller will acquire the engine's actual speed in real time and calculate the difference between the actual speed and the target speed at that time.

[0125] The difference is used to characterize the degree of deviation of the current engine speed from the desired speed, serving as the basis for closed-loop adjustment of the drag torque.

[0126] Step 4.2: Determine the current driving torque based on the difference.

[0127] In this step, the torque value corresponding to the difference can be determined by using a pre-built difference-torque mapping relationship, thus obtaining the current driving torque.

[0128] The difference-torque mapping relationship indicates that when the difference is large, a higher driving torque is output to accelerate the engine speed; as the difference gradually decreases, the output torque decreases synchronously to avoid engine speed overshoot. In practical applications, this difference-torque mapping relationship can be established offline using calibration data, and can take the form of a calibration table, a function model, or a piecewise linear relationship.

[0129] Step 4.3: Control the drive motor to apply drag torque to the engine.

[0130] In this step, the controller sends a control command carrying the drag torque to the drive motor so that the drive motor applies the drag torque to the engine.

[0131] In practice, the drive motor can receive torque commands through an inverter and convert the current control quantity into the corresponding electromagnetic drag torque, thereby applying external driving torque to the engine crankshaft.

[0132] The control method described in steps 4.1 to 4.2 above can continuously correct the output torque of the drive motor as the actual engine speed gradually approaches the current target speed: when the speed difference is large at the beginning of startup, a large drag torque is applied to overcome the high frictional resistance and make the speed rise rapidly; when the actual speed approaches the target speed, the drag torque is reduced linearly or curvilinearly, and then enters the speed closed-loop maintenance stage to ensure that the engine speed steadily approaches the target speed, providing a stable speed basis for subsequent fuel injection and ignition.

[0133] Because the drag torque is adaptively adjusted according to the difference, it can reduce the speed fluctuation caused by traditional fixed torque control, improve the continuity and controllability of the engine acceleration process, reduce overshoot and vibration near the target speed, and improve engine start response and vehicle sound and vibration roughness performance.

[0134] S204: When the time the difference between the actual engine speed and the current target speed is within the target allowable difference range reaches a preset time, control the engine to inject fuel and ignite.

[0135] The allowable range of the target difference is determined based on the engine's coolant temperature.

[0136] In this step, since the engine is in cold start mode, the controller will control the engine to inject fuel and ignite when the difference between the actual engine speed and the current target speed is within the target allowable difference range for a preset time during the process of real-time control of the starter motor to apply driving torque to the engine.

[0137] The target allowable difference range is used to limit the permissible deviation between the actual engine speed and the target speed, and its range is determined based on the current coolant temperature of the engine; the preset time is used to confirm the continuity of the difference meeting the conditions, so as to avoid false ignition caused by instantaneous speed disturbances.

[0138] In practical applications, during this engine start-up process, the target allowable difference range can be a fixed range. For example, this target allowable difference range can be determined based on the initial coolant temperature of the engine and maintained unchanged during the determination process based on the continuity of the difference. Alternatively, the target allowable difference range can also be a range that dynamically changes with the coolant temperature. For example, before fuel injection ignition, the target difference range corresponding to the coolant temperature at each moment can be continuously acquired until the duration for which the difference between the actual engine speed and the target speed is within the target difference range is greater than a preset time.

[0139] Meanwhile, regarding methods for determining the target difference range based on coolant temperature, for example, different allowable difference ranges can be preset for different temperature ranges: the allowable deviation range for high temperature ranges is relatively small, and the allowable deviation range for low temperature ranges is relatively large.

[0140] This method fully considers the challenges of cold start mode, where the engine oil is viscous, internal engine friction is high, and the motor experiences inertial spikes and oscillations when driving the engine to the target speed, making stable ignition impossible. By maintaining a stable engine speed within a preset range for a period before ignition and fuel injection, this method ensures that ignition occurs at a time when the engine speed is stable and combustion conditions are relatively optimal during cold start mode. This avoids the mutual tension between engine output torque and P1 motor torque caused by unstable combustion, achieving a "soft transition" and seamless connection between the drive motor driving phase and the engine combustion phase in cold start mode, thus improving NVH performance in cold start mode.

[0141] The engine start control method provided in this application determines the target engine speed based on the maximum discharge capacity of the vehicle's power battery and the coolant temperature, and controls the engine fuel injection and ignition when the difference between the actual engine speed and the target speed is within the target allowable difference range for a preset time. This effectively ensures the engine's start efficiency, ignition reliability, and NVH performance in cold start mode.

[0142] Furthermore, Figure 3 This is a flowchart illustrating an engine start-up control method provided in Embodiment 3 of this application, as shown below. Figure 3 As shown, based on the above embodiments, the method includes:

[0143] S301: In response to the vehicle's engine start request, determine that the engine start mode is the warm engine start mode.

[0144] In this embodiment, the engine starting mode is determined to be a hot engine start mode based on the initial coolant temperature of the vehicle's transmitter when it receives the start request.

[0145] S302: Determine the current target engine speed based on the current engine coolant temperature and the preset first mapping relationship.

[0146] In this step, the target speed that is compatible with the current coolant temperature will be determined based on the engine's current coolant temperature and the pre-established second mapping model.

[0147] Specifically, in this first mapping relationship, the coolant temperature is shown to be negatively correlated with the target speed. The design purpose is to allow for a reduction in system load when the coolant temperature is low, and a higher target speed when the coolant temperature is relatively high, facilitating rapid start-up. In practical applications, this first mapping relationship can be established offline using calibration data, and can be in the form of a preset curve, table, or function.

[0148] In one possible implementation, the target speed can be determined based on the current coolant temperature only after the current start-up mode is determined to be a warm-up start-up, and this target speed can be continuously used to determine the driving torque during the subsequent start-up process. Alternatively, in another possible implementation, the current target speed of the vehicle can be dynamically determined in real time or at a preset frequency based on the current coolant temperature of the engine during the entire start-up phase before engine fuel injection and ignition, so as to ensure that the target speed is always consistent with the current thermal state of the engine.

[0149] In hot start mode, after determining that the engine is at a high temperature, the controller determines the target speed based solely on the current coolant temperature. Since the internal frictional resistance of the engine is low and the available starting torque demand is relatively stable in a hot start state, the target speed can be directly obtained from the coolant temperature, shortening the control calculation path and improving response speed, thus achieving a simpler, more stable, and faster start-up control.

[0150] S303: Real-time control of the drive motor to output traction torque to the engine according to the current target speed, so that the actual speed of the engine approaches the target speed.

[0151] For a detailed explanation of this step, please refer to step S203 in the aforementioned embodiment two, which will not be repeated here.

[0152] S304: Control engine fuel injection and ignition when the actual speed reaches the current target speed.

[0153] In this step, since the engine is in a hot start mode, the controller will control the engine to inject fuel and ignite when the engine's actual speed reaches the current target speed, while controlling the starter motor to apply driving torque to the engine in real time.

[0154] In other words, when the engine is set to start in warm-up mode, the engine will be immediately controlled to inject fuel and ignite when the actual engine speed is detected to have reached the current target speed.

[0155] This method fully considers that in the hot engine start-up mode, the engine coolant temperature is sufficient, the oil has good fluidity and low internal friction resistance, and there is almost no oscillation after the speed reaches the target value, and it is in a stable operating condition instantly. Therefore, by controlling ignition when the target speed is reached, the starting efficiency of the engine in the hot engine start-up mode is effectively guaranteed.

[0156] The engine start control method provided in this application effectively ensures the engine start efficiency and NVH performance in the hot start mode by determining the target engine speed based on the coolant temperature of the electric motor and controlling the engine fuel injection and ignition when the actual engine speed reaches the current target speed.

[0157] As in Embodiments 2 and 3 above, a fuel injection ignition timing determination method was designed to differentiate between different start-up modes. A more stringent speed stability criterion was adopted during cold engine start-up, and a more direct speed arrival criterion was adopted during hot engine start-up. This ensures that, under all operating conditions, the engine can maintain high original engine start-up efficiency and excellent NVH performance during the transition from being driven by the drive motor to combustion establishment.

[0158] Furthermore, in one possible implementation, the means of "determining the current drag torque based on the difference" as described in the above embodiment may include the following steps 3.2.1 to 3.2.2:

[0159] The current driving torque is determined based on the difference, the current engine coolant temperature, and a preset second mapping relationship. The second mapping relationship is a mapping relationship between the difference, the driving torque, and the coolant temperature. The difference and the driving torque, as well as the coolant temperature and the driving torque, are negatively correlated.

[0160] In other words, in this implementation, based on the difference between the actual engine speed and the target speed, the current driving torque will also be dynamically determined in conjunction with the engine coolant temperature, so as to further improve the NVH performance of engine start-up control.

[0161] Specifically, the second mapping relationship can be established offline using calibration data, and can take the form of a two-dimensional calibration table, a function expression, or a piecewise function. For example, if the second mapping relationship is in the form of a two-dimensional calibration table, then the horizontal axis of the two-dimensional calibration table can correspond to the difference, the vertical axis can correspond to the coolant temperature, and the table entries can correspond to the drag torque output value. As the difference increases, the drag torque corresponding to the table entry decreases; as the coolant temperature rises, the drag torque corresponding to the table entry also decreases, so that the engine reduces external drag input when approaching the target speed or when the thermal resistance is low.

[0162] The method provided in this implementation establishes a negative correlation between the torque difference and the driving torque, as well as between the coolant temperature and the driving torque. This allows for a larger driving torque output to the engine when it is not yet approaching the target speed and is at a relatively low temperature. Conversely, as the engine gradually approaches the target speed or the coolant temperature rises, the driving torque output to the engine decreases accordingly, thus achieving a smooth transition. Furthermore, this configuration allows for the application of a relatively larger driving torque to the engine during cold starts and a relatively smaller driving torque to the engine during warm starts, at the same speed difference. This achieves precise matching between torque and operating resistance, further comprehensively improving NVH performance under various starting conditions.

[0163] Furthermore, based on the above embodiments, the method provided in this application may further include:

[0164] After successful fuel injection and ignition, the output torque of the drive motor is controlled to change from the driving torque to the generating torque. The slope of the torque change in the zero-value region (also known as the NVH sensitive range) is used to drive the output torque to quickly cross the zero-value region along a single trend. It should be noted that this implementation focuses on the engine's NVH performance during the process of the engine gradually changing from a "positive" driving torque to a "negative" generating torque after successful ignition.

[0165] In detail, successful fuel injection and ignition means that after fuel injection and ignition, the engine has established a continuous combustion capability and can output the engine torque required to maintain operation. At this point, the engine has completed starting. Generating torque is the output torque of the drive motor when it enters the generator mode after the engine has started. Its function is to convert some of the engine's mechanical energy into electrical energy to power the battery or high-voltage electrical equipment.

[0166] In the actual torque switching process, the motor output torque switching adopts a ramp transition method. That is, in each control cycle, the controller reduces the output power indicated in the current motor torque control command according to the set torque change slope, so that the driving torque smoothly decays to near zero, and continues to adjust to the target generating torque. The "zero value region" mentioned in this implementation refers to the torque transition range centered on the zero torque value during the process of the motor output torque gradually decaying from the forward driving torque to the reverse target generating torque, such as the range of output torque from -7 N·m to 7 N·m.

[0167] This implementation uniquely designs the slope of the output torque change in the zero-value region to drive the output torque to quickly pass through the zero-value region along a single trend. Specifically, the slope of the output torque change when passing through the zero-value interval needs to be configured as a monotonically changing slope with a high amplitude.

[0168] As a specific example, the maximum torque change slope allowed by the drive motor hardware can be directly set to the change slope within the zero value range.

[0169] As another specific example, the slope of torque change in the zero-value region can also be pre-calibrated by testing the engine's NVH characteristics when the drive motor crosses the zero-value region with different torque change slopes.

[0170] Specifically, multiple sets of different torque change slopes can be pre-configured, and bench tests or real vehicle calibration tests can be carried out for each set. Each slope is used as the torque adjustment slope in the zero value range, and the NVH characteristics of the engine (such as engine knock peaks) are measured when the drive motor crosses the zero value region. The torque change slope with the best NVH characteristics is selected and determined as the target torque change slope in the zero value region, which is used to adjust the output torque of the drive motor after successful fuel injection and ignition.

[0171] For example, the slope of the torque change is, for instance, 28 N·m / s, or other values ​​less than 28 N·m / s.

[0172] Based on the above analysis, this implementation method enables the output torque of the drive motor to monotonically and quickly traverse a small range near zero torque in a manner with a slope higher than usual. Consequently, the combined torque formed by the engine torque and motor torque acting together on the crankshaft can quickly cross the zero value region, thereby avoiding structural knocking caused by torque balancing or oscillating in this range.

[0173] The method provided in this implementation addresses the root cause of the specific NVH problem of "torque-sensitive range dwelling". By enabling the output torque of the drive motor to quickly pass through the sensitive zero value region, it achieves targeted elimination of the knocking vibration problem and further improves the overall NVH performance of the vehicle.

[0174] Figure 4 This is a schematic diagram of the structure of an engine start control device provided in Embodiment 4 of this application, as shown below. Figure 4 As shown, the engine start control device 40 provided in this embodiment includes:

[0175] The first determining module 401 is used to determine the engine starting mode based on the initial coolant temperature when the engine receives the engine starting request in response to the vehicle's engine start request.

[0176] The first control module 402 is used to control the vehicle's drive motor to output drag torque to the engine according to the current target speed in real time, so that the actual speed of the engine approaches the target speed.

[0177] The second control module 403 is used to control the engine to perform fuel injection and ignition according to the starting mode, actual speed and target speed, so as to start the engine.

[0178] The engine start control device 40 provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0179] Figure 5 This is a schematic diagram of the structure of an engine start control device provided in Embodiment 5 of this application, as shown below. Figure 5 As shown, based on the above embodiments, the engine start control device 40 provided in this embodiment further includes:

[0180] The second determining module 404 is used to determine the current target speed of the engine based on the current coolant temperature of the engine.

[0181] The third control module 405 is used to control the output torque of the drive motor to be adjusted from the driving torque to the generating torque after successful fuel injection and ignition.

[0182] The slope of the output torque change in the zero region is used to drive the output torque to quickly pass through the zero region along a single trend.

[0183] In one possible embodiment, the second control module 403 is configured to:

[0184] If the starting mode is cold start mode, the engine will be controlled to inject fuel and ignite when the difference between the actual speed and the target speed is within the target allowable difference range for a preset duration. The target allowable difference range is determined based on the engine coolant temperature.

[0185] If the starting mode is warm-up start mode, the engine will be controlled to inject fuel and ignite when the actual speed reaches the target speed.

[0186] In one possible embodiment, the second determining module 404 is specifically used for:

[0187] When the starting mode is cold start mode, the target engine speed is determined based on the vehicle's current maximum discharge capacity of the power battery and the current engine coolant temperature; or,

[0188] When the starting mode is the hot engine start mode, the current target speed of the engine is determined based on the current coolant temperature of the engine and the preset first mapping relationship; the first mapping relationship is the mapping relationship between coolant temperature and target speed.

[0189] In one possible embodiment, the first control module 402 includes:

[0190] The acquisition unit is used to acquire the difference between the actual rotational speed and the target rotational speed in real time;

[0191] The determining unit is used to determine the current driving torque based on the difference;

[0192] The control unit is used to control the drive motor to apply drag torque to the engine.

[0193] In one possible embodiment, the determining unit is specifically used for:

[0194] The current drag torque is determined based on the difference, the current engine coolant temperature, and the preset second mapping relationship;

[0195] The second mapping relationship is the mapping relationship between the difference, the driving torque, and the coolant temperature. There is a negative correlation between the difference and the driving torque, and between the coolant temperature and the driving torque.

[0196] In one possible embodiment, the first determining module 401 is specifically used for:

[0197] Obtain the initial coolant temperature and initial catalyst temperature of the engine when it receives the start request;

[0198] When the initial coolant temperature is greater than the first preset threshold and the initial catalyst temperature is greater than the second preset threshold, the engine start mode is determined to be the warm engine start mode; otherwise, the engine start mode is determined to be the cold engine start mode.

[0199] The engine start control device 40 provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0200] Figure 6 This is a schematic diagram of the structure of a controller provided in Embodiment Six of this application. Figure 6As shown, the controller 50 provided in this embodiment includes at least one processor 501 and a memory 502. Optionally, the controller 50 further includes a communication component 503. The processor 501, memory 502, and communication component 503 are connected via a bus 504.

[0201] In a specific implementation, at least one processor 501 executes computer execution instructions stored in memory 502, causing at least one processor 501 to perform the above-described method.

[0202] The specific implementation process of processor 501 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0203] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0204] The memory may include read-only memory and random access memory. The memory may be volatile or non-volatile, or may include both. Non-volatile memory may include read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory may include random access memory (RAM), which serves as an external cache. Many forms of RAM are available by way of example, but not limitation. Examples include Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced Synchronous DRAM (ESDRAM), Sync Link DRAM (SLDRAM), and Direct Rambus RAM (DR RAM).

[0205] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0206] This application also provides a vehicle including a vehicle body and the aforementioned controller. The controller is used to implement the above-described method.

[0207] This application also provides a computer program product, including a computer program that, when executed, implements the above-described method.

[0208] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed, implement the above-described method.

[0209] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as SRAM, EEPROM, EPROM, PROM, ROM, magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0210] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside within an ASIC. Alternatively, the processor and the readable storage medium can exist as discrete components in a device.

[0211] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0212] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0213] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0214] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, 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 a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0215] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0216] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

[0217] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. An engine starting control method, characterized in that, include: In response to a vehicle's engine start request, the engine start mode is determined based on the initial coolant temperature of the engine when the start request is received. The vehicle's drive motor is controlled in real time to output traction torque to the engine according to the current target speed, so that the actual speed of the engine approaches the target speed; Based on the starting mode, the actual speed, and the target speed, the engine is controlled to perform fuel injection and ignition to start the engine.

2. The method according to claim 1, characterized in that, The step of controlling the engine to perform fuel injection and ignition to start the engine based on the starting mode, the actual speed, and the target speed includes: If the starting mode is a cold start mode, then when the time for which the difference between the actual speed and the target speed is within the target allowable difference range reaches a preset duration, the engine is controlled to inject fuel and ignite. The target allowable difference range is determined based on the engine coolant temperature. If the starting mode is a warm-up start mode, then when the actual speed reaches the target speed, the engine is controlled to inject fuel and ignite.

3. The method according to claim 1, characterized in that, Also includes: The current target speed of the engine is determined based on the current coolant temperature of the engine.

4. The method according to claim 3, characterized in that, The real-time determination of the engine's current target speed based on the engine's current coolant temperature includes: When the starting mode is cold start mode, the current target speed of the engine is determined based on the current maximum discharge capacity of the vehicle's power battery and the current coolant temperature of the engine; or, When the starting mode is the hot engine start mode, the current target speed of the engine is determined according to the current coolant temperature of the engine and a preset first mapping relationship; the first mapping relationship is the mapping relationship between coolant temperature and target speed.

5. The method according to any one of claims 1 to 4, characterized in that, The real-time control of the vehicle's drive motor to output drag torque to the engine according to the current target speed includes: The difference between the actual rotational speed and the target rotational speed is obtained in real time; Based on the difference, determine the current drag torque; The drive motor is controlled to apply the drag torque to the engine.

6. The method according to claim 5, characterized in that, Determining the current drag torque based on the difference includes: The current drag torque is determined based on the difference, the current coolant temperature of the engine, and a preset second mapping relationship; The second mapping relationship is the mapping relationship between the difference, the driving torque and the coolant temperature, wherein the difference and the driving torque, and the coolant temperature and the driving torque are both negatively correlated.

7. The method according to any one of claims 1 to 4, characterized in that, Also includes: After successful fuel injection and ignition, the output torque of the drive motor is adjusted from the drag torque to the generator torque. The slope of the output torque change in the zero-value region is used to drive the output torque to quickly pass through the zero-value region along a single trend.

8. An engine starting control device, characterized in that, include: The first determining module is used to determine the engine start mode based on the initial coolant temperature of the engine when the engine receives the start request in response to the vehicle's engine start request. The first control module is used to control the vehicle's drive motor to output drag torque to the engine according to the current target speed in real time, so that the actual speed of the engine approaches the target speed. The second control module is used to control the engine to perform fuel injection and ignition according to the start-up mode, the actual speed and the target speed, so as to start the engine.

9. A vehicle, characterized in that, The vehicle includes a vehicle body and a controller; the controller is used to implement the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-7.

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