Hybrid transmission lubricant active heating control method, system, and vehicle

Abstract

The application discloses a kind of hybrid transmission lubricating oil active heating control method, system and vehicle, it is related to hybrid electric vehicle control technical field, is realized by the interaction between front motor control unit and vehicle control unit, and front motor control unit executes: after detecting that vehicle starts and hybrid transmission assembly high voltage is powered on, real-time detection lubricating oil temperature and judge whether lower than first temperature threshold, if yes, then send active heating request to vehicle control unit;If active heating permission instruction is received, then start active heating mode and feedback, again execute torque control within the maximum allowable power limit received, while regulating motor and inverter heat power is promoted to heat lubricating oil, and actual heating power is fed back in real time;When lubricating oil temperature reaches second temperature threshold, send exit active heating mode request to vehicle control unit, after receiving exit active heating permission instruction, exit active heating mode and execute normal torque control.

Description

Technical Field

[0001] This invention relates to the field of hybrid vehicle control technology, and in particular to a method, system, and vehicle for active heating control of lubricating oil in hybrid transmissions. Background Technology

[0002] As a core component of hybrid vehicles, hybrid transmissions typically include an oil pump. The oil pump delivers lubricating oil to the gears and bearings to reduce friction and wear. The reliability of the lubrication system directly affects the overall vehicle performance and service life.

[0003] However, due to the significant increase in lubricant viscosity and sharp decrease in fluidity at low temperatures, hybrid transmissions using only an electronic oil pump struggle to effectively deliver lubricant to various lubrication points under cold conditions. This can easily lead to poor lubrication of components such as gear pairs and bearings, affecting the transmission's lifespan. Currently, auxiliary lubrication is typically achieved by adding a mechanical oil pump. Driven by the engine or electric motor, the mechanical oil pump can provide a certain flow rate of lubricant at low temperatures. However, this approach is difficult to implement, increasing the size and cost of the transmission. Furthermore, the uncontrollable flow rate of the mechanical oil pump reduces system reliability and negatively impacts the user experience. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a method, system, and vehicle for active heating control of lubricating oil in hybrid transmissions. Utilizing the existing motor and inverter in the transmission assembly as heating sources, it achieves active heating of the lubricating oil without adding a mechanical oil pump. This reduces the viscosity of the lubricating oil and improves its fluidity, solving problems such as insufficient low-temperature fluidity of lubricating oil in hybrid transmissions, ineffective lubrication with a standalone electronic oil pump, and the impact of adding a mechanical oil pump on reliability in existing technologies. It can effectively reduce system cost and size, and improve the reliability of the entire vehicle in low-temperature environments.

[0005] In a first aspect, the present invention provides a method for active heating control of lubricating oil in a hybrid transmission.

[0006] A method for active heating control of lubricating oil in a hybrid transmission is implemented through interaction between a front motor control unit and a vehicle control unit, wherein the front motor control unit is used to execute: After detecting that the vehicle has started and the hybrid transmission assembly is powered on, the lubricating oil temperature is monitored in real time and it is determined whether it is below the first temperature threshold. If so, an active heating request is sent to the vehicle control unit. If an active heating permission command is received, the active heating mode is activated and feedback is provided. Then, within the received maximum allowable power limit, torque control is performed, and the motor and inverter are adjusted to increase the heating power to heat the lubricating oil. The actual heating power is fed back in real time. When the lubricating oil temperature reaches the second temperature threshold, a request to exit active heating is sent to the vehicle control unit. After receiving the exit active heating permission command, the active heating mode is exited and normal torque control is executed.

[0007] In a further technical solution, the vehicle control unit is used to perform: After receiving the active heating request from the front motor control unit, the vehicle battery pack status is assessed to determine whether heating is allowed. If allowed, an active heating permission command is sent to the front motor control unit. After receiving the active heating mode start signal from the front motor control unit, the maximum allowable heating power limit is sent to the front motor control unit. Upon receiving the request to exit active heating from the front motor control unit, the system issues an exit active heating permission command to the front motor control unit.

[0008] A further technical solution involves the vehicle control unit assessing the battery pack status based on its state of charge, temperature, and maximum permissible discharge power to determine whether heating is permitted, including: If the following conditions are met simultaneously: the battery pack state of charge is higher than the set lower limit, the battery pack temperature is higher than the set lower limit, and the current maximum allowable continuous discharge power calculated by the BMS is higher than the minimum power required for active heating, then heating is allowed and an active heating allow command is issued; otherwise, heating is not allowed.

[0009] A further technical solution involves the vehicle control unit sending a torque limiting command to the front motor control unit to limit the maximum output torque of the transmission to a preset ratio of the rated torque, thereby performing torque control during the lubricating oil heating process. During the lubricating oil heating process, the front motor control unit detects the lubricating oil temperature in real time and determines whether the second temperature threshold has been reached. If so, it sends a request to exit active heating to the vehicle control unit. After receiving the request to deactivate active heating, the vehicle control unit releases the limitation on the transmission output torque.

[0010] A further technical solution is that when the vehicle control unit evaluates that the battery pack status does not meet the conditions and rejects the active heating request, the front motor control unit resends the active heating request to the vehicle control unit after a set time interval, and the vehicle control unit maintains the limitation on the maximum output torque of the transmission during the re-request period.

[0011] A further technical solution is to trigger a fault prompt if the front motor control unit continuously sends active heating requests for a duration exceeding the set time without obtaining permission.

[0012] Further technical solutions increase heat dissipation power by controlling the operating status of the motor and inverter, including: Increasing motor copper losses by injecting d-axis excitation current into the motor; Increase inverter switching losses by adjusting the inverter's PWM switching frequency.

[0013] A further technical solution is that when the lubricating oil temperature sensor malfunctions, the front motor control unit switches to a degraded control mode and calculates the lubricating oil temperature based on the ambient temperature detected by the ambient temperature sensor and the vehicle's parking time. When the calculated lubricating oil temperature is lower than the first temperature threshold, an active heating request is sent to the vehicle control unit.

[0014] A further technical solution involves the front motor control unit starting the electronic oil pump after exiting the active heating mode, establishing a lubricating oil circulation to provide lubrication and cooling for the gear pair, bearings, and motor.

[0015] Secondly, the present invention provides an active heating control system for lubricating oil in hybrid transmissions.

[0016] A hybrid transmission lubricating oil active heating control system includes: a lubricating oil temperature sensor, a motor and an inverter, an electronic oil pump, a front motor control unit, and a vehicle control unit; The lubricating oil temperature sensor is used to detect the lubricating oil temperature and feed it back to the front motor control unit; The motor and inverter are used to increase the heating power to heat the lubricating oil after receiving a heating command from the front motor control unit; The electronic oil pump is used to establish a lubricating and cooling oil circulation after the lubricating oil temperature reaches a preset range; The front motor control unit interacts with the vehicle control unit to implement the above-mentioned active heating control method for hybrid transmission lubricating oil.

[0017] Thirdly, the present invention also provides a vehicle including the above-described active heating control system for hybrid transmission lubricating oil, or performing the above-described active heating control method for hybrid transmission lubricating oil.

[0018] Fourthly, the present invention also provides an electronic device, comprising: a memory for storing executable instructions; and a processor for implementing the above-described active heating control method for hybrid transmission lubricating oil when executing the executable instructions stored in the memory.

[0019] Fifthly, the present invention also provides a computer-readable storage medium storing executable instructions for causing a processor to execute the executable instructions to implement the above-described active heating control method for lubricating oil in a hybrid transmission.

[0020] The above one or more technical solutions have the following beneficial effects: This invention provides a method, system, and vehicle for active heating control of lubricating oil in hybrid transmissions. The method is applied to hybrid vehicles and utilizes the existing motor and inverter in the hybrid transmission assembly as heating sources. Through software strategies, the wasted power of the motor and inverter is converted into heat energy to actively heat the lubricating oil. This effectively solves the problem that an electronic oil pump alone cannot deliver lubricating oil in low-temperature environments. Moreover, it achieves reliable lubrication of the hybrid transmission without adding a mechanical oil pump, reducing system cost and size, and improving the reliability of the vehicle and user experience in low-temperature environments.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a flowchart of the active heating control method for lubricating oil in a hybrid transmission proposed in an embodiment of the present invention. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are exemplary and are intended only to describe specific embodiments and to provide further explanation of the invention, and are not intended to limit the scope of exemplary embodiments of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Terminology Explanation Lubricating oil: refers to the automatic transmission fluid (ATF) used inside the hybrid transmission assembly. It adopts a single oil circuit circulation design and performs both lubrication and cooling functions. It is driven by an electronic oil pump to circulate inside the transmission.

[0026] Front Motor Control Unit (FMCU): Responsible for controlling the generator and drive motor in the hybrid transmission assembly, performing functions such as vector control, inverter PWM drive, and fault diagnosis.

[0027] Vehicle Control Unit (HCU): This refers to the Hybrid Control Unit, which is responsible for functions such as vehicle energy flow management, torque distribution, and battery pack status monitoring. It communicates with controllers such as FMCU and BMS (Battery Management System) via the CAN bus.

[0028] d-axis excitation current: refers to the direct-axis magnetizing current component injected into the stator winding of the motor in FOC (field-oriented control, also known as vector control). This current does not generate effective torque, but it will increase the copper loss of the motor and convert electrical energy into heat energy.

[0029] As noted in the background section, existing hybrid transmissions employ a lubrication scheme using an electronic oil pump and / or a mechanical oil pump. The mechanical oil pump is driven by the engine or electric motor and provides a certain flow rate of lubricating oil at low temperatures. The electronic oil pump serves as an auxiliary, supplementing the lubricating oil supply when the flow rate of the mechanical oil pump is insufficient. Some hybrid transmissions that use a pure electronic oil pump scheme force the delivery of lubricating oil to each lubrication point by increasing the drive power of the electronic oil pump under low-temperature operating conditions.

[0030] However, existing solutions suffer from problems such as uncontrollable flow rate, large size, and difficult placement of mechanical oil pumps. Furthermore, the drive power requirement of mechanical oil pumps increases at low temperatures, increasing the burden on the engine or motor. In the case of using only electronic oil pumps, the viscosity of the lubricating oil becomes too high at low temperatures. Even if the drive power of the electronic oil pump is increased, it cannot effectively deliver the lubricating oil, resulting in poor lubrication of components such as gear pairs and bearings, accelerating wear, and failing to meet the reliability requirements of hybrid transmissions in low-temperature environments.

[0031] To address the aforementioned problems, this invention proposes an active heating control method for lubricating oil in hybrid transmissions. This method utilizes the existing motor and inverter in the hybrid transmission assembly as heating sources, and uses software strategies to control the waste power of the motor and inverter to convert it into heat energy for active heating of the lubricating oil, thus solving the above-mentioned technical defects.

[0032] In other words, to address the problem of insufficient low-temperature fluidity of lubricating oil in existing hybrid transmission technologies, this invention provides an active heating control scheme for hybrid transmission lubricating oil. This scheme first, after the vehicle starts and the hybrid transmission assembly is powered on, the front motor control unit monitors the lubricating oil temperature in real time. If the temperature is below a first temperature threshold, it sends an active heating request to the vehicle control unit. The vehicle control unit assesses the vehicle battery pack status to determine whether heating is permitted. If permitted, it issues a maximum permissible heating power limit and an active heating permission command. Within the maximum permissible heating power limit, the front motor control unit performs normal torque control, simultaneously regulating the motor and inverter to increase the heating power to heat the lubricating oil, and provides real-time feedback on the actual heating power. When the lubricating oil temperature reaches a second temperature threshold, it sends a request to exit active heating to the vehicle control unit, exiting the active heating mode and executing conventional speed drive control. This scheme effectively solves the problem of insufficient lubricating oil delivery using only an electronic oil pump in low-temperature environments without adding a mechanical oil pump, a significant difference from existing solutions that require adding a mechanical oil pump or increasing the drive power of the electronic oil pump.

[0033] Furthermore, example environments in which several embodiments of this solution can be implemented are first given, including hybrid vehicles equipped with hybrid transmission assemblies and vehicle control systems.

[0034] The aforementioned hybrid vehicle is equipped with a hybrid transmission assembly, which includes components such as a generator (P1), a drive motor (P3), an inverter, an electronic oil pump, a lubricating oil temperature sensor, and an ambient temperature sensor. The generator is directly connected to the engine via the crankshaft and cannot be decoupled; similarly, the drive motor is directly connected to the wheels via reduction gears and cannot be decoupled. Under low-temperature conditions, because the generator and engine, and the drive motor and wheels cannot be decoupled, splash lubrication using the motor to agitate the lubricating oil is impossible. Therefore, an electronic oil pump is needed to establish lubricating oil circulation.

[0035] The hybrid transmission system includes a lubricating oil temperature sensor, installed at the return port of the drive motor cooling oil circuit. This sensor is an NTC thermistor type, with a measurement range of -40°C to 150°C and an accuracy of ±2°C. It monitors the lubricating oil temperature in real time and transmits the signal to the FMCU. Preferably, an ambient temperature sensor is also included, installed externally to detect the ambient temperature. When the lubricating oil temperature sensor malfunctions, the FMCU calculates the lubricating oil temperature based on the ambient temperature detected by the sensor and the vehicle's parking time.

[0036] The electronic oil pump is powered by a 12V auxiliary battery, with a rated flow rate of 15 L / min and a maximum working pressure of 8 bar. It is controlled by the FMCU to start and stop, and starts after the lubricating oil temperature reaches the second temperature threshold to establish lubricating oil circulation and provide lubrication and cooling for gear pairs, bearings and motors.

[0037] The aforementioned vehicle control system includes controllers such as the vehicle control unit (HCU), the front motor control unit (FMCU), and the battery management system (BMS), which communicate with each other via a CAN bus. The HCU is responsible for vehicle energy flow management, torque distribution, and battery pack status monitoring; the FMCU is responsible for controlling the generator and drive motor, performing vector control, inverter PWM drive, and fault diagnosis; and the BMS is responsible for battery pack status monitoring and charge / discharge management.

[0038] In the above process, data collection and processing strictly comply with relevant laws and regulations. Data such as lubricating oil temperature, ambient temperature, and vehicle location must be authorized and used only for the active heating control of lubricating oil in hybrid transmissions, and not for other unauthorized purposes.

[0039] It should be understood that the example environment is described for illustrative purposes only and does not imply any limitation on the scope of the invention. The invention can also be applied to other hybrid architectures (such as P2, P2.5, P4, etc.), and the environment may also include components such as sensors and communication modules not shown.

[0040] Example 1 like Figure 1 As shown, this embodiment provides a method for active heating control of lubricating oil in a hybrid transmission. This method is applied to hybrid vehicles and is implemented through the interaction between the front motor control unit and the vehicle control unit. The method includes the following steps: Step S101: After detecting that the vehicle has started and the hybrid transmission assembly is powered on, the front motor control unit detects the lubricating oil temperature in real time and determines whether it is lower than the first temperature threshold. If so, it sends an active heating request to the vehicle control unit.

[0041] In this embodiment, vehicle start-up refers to the driver turning the vehicle key to the ON position or pressing the start button, and the vehicle entering the ready state; high-voltage power-on of the hybrid transmission assembly refers to the vehicle control unit (HCU) sending a high-voltage power-on command to the front motor control unit (FMCU), and the FMCU controlling the inverter to provide high-voltage power to the generator and drive motor, so that the motor is in a controllable state; the lubricating oil temperature detection is completed by an NTC thermistor temperature sensor installed at the return port of the cooling oil circuit of the drive motor. The sensor has a measurement range of -40°C to 150°C and an accuracy of ±2°C. The FMCU reads the sensor resistance value in real time through the analog signal acquisition circuit and calculates the lubricating oil temperature according to the preset resistance-temperature characteristic curve. The sampling period is 100ms.

[0042] Specifically, the front motor control unit (FMCU) monitors the lubricating oil temperature in real time and compares this real-time temperature with a first temperature threshold. This first temperature threshold is the lubricating oil temperature threshold that triggers an active heating request; in this embodiment, the first temperature threshold is set to -15°C. When the FMCU detects that the lubricating oil temperature is below -15°C, it determines that the lubricating oil has insufficient fluidity and the electronic oil pump cannot effectively deliver the lubricating oil, requiring the activation of the active heating mode. At this time, the FMCU sends an active heating request signal, FMCU_ActiveheatReq=Request, to the HCU via the CAN bus.

[0043] It should be noted that the setting of the first temperature threshold needs to comprehensively consider the low-temperature flow properties of the lubricating oil, the delivery capacity of the electronic oil pump, and the starting requirements of the vehicle in low-temperature environments. In this embodiment, the range of the first temperature threshold is -20℃ to -10℃, which can be adjusted according to different lubricating oil types and the performance of the electronic oil pump.

[0044] Step S101 solves the problem of insufficient low-temperature fluidity of lubricating oil in the prior art, enabling real-time monitoring of lubricating oil temperature and timely triggering of active heating requests, thus providing a prerequisite for the subsequent activation of the active heating mode.

[0045] As another implementation, when the lubricating oil temperature sensor malfunctions, the front motor control unit switches to degraded control mode and calculates the lubricating oil temperature based on the ambient temperature detected by the ambient temperature sensor and the vehicle's parking time; when the calculated lubricating oil temperature is lower than the first temperature threshold, it sends an active heating request to the vehicle control unit.

[0046] In this embodiment, if the FMCU detects a malfunction in the lubricating oil temperature sensor (e.g., the sensor signal is outside the normal range, the sensor is open-circuited or short-circuited, etc.), the FMCU switches to degraded control mode.

[0047] In degraded control mode, the FMCU reads the ambient temperature detected by the ambient temperature sensor via the CAN bus and, combined with the vehicle's parking time, calculates the lubricating oil temperature. The calculation logic is as follows: (1) If the ambient temperature is below -15°C and the vehicle has been parked for more than 4 hours, it is assumed that the lubricating oil temperature has dropped below -15°C, and the FMCU sends an active heating request to the HCU. (2) If the ambient temperature is higher than -15°C or the vehicle is parked for less than 4 hours, the lubricating oil temperature is presumed to be higher than -15°C, and the FMCU will not send an active heating request.

[0048] The degraded control mode calculation logic is based on an empirical model, taking into account the influence of ambient temperature on lubricating oil temperature and the influence of vehicle parking time on lubricating oil heat dissipation. In this embodiment, the first temperature threshold is set to -15°C and the second temperature threshold is set to -5°C, which can be adjusted according to different lubricating oil types and vehicle parking environments.

[0049] It should be noted that the calculation accuracy of the degraded control mode is lower than that of the measured accuracy of the normal control mode, but it can provide basic active heating control function when the lubricating oil temperature sensor fails, ensuring reliable lubrication of the hybrid transmission.

[0050] The above method solves the problem of the inability to perform active heating control when the lubricating oil temperature sensor fails in the existing technology, realizes the switching of degraded control mode and the calculation of lubricating oil temperature, and improves the fault tolerance and reliability of the whole vehicle.

[0051] By employing a sensor failure degradation control mode, when the lubricating oil temperature sensor malfunctions, the system calculates the lubricating oil temperature based on the ambient temperature and vehicle parking time. This ensures the system can still provide basic active heating functionality even in sensor failure conditions, improving the system's fault tolerance and robustness. In degradation control mode, if the ambient temperature is below -15°C and the vehicle has been parked for more than 4 hours, the lubricating oil temperature is presumed to have dropped below -15°C, and the system automatically sends an active heating request to the vehicle control unit. Although the calculation accuracy of degradation control mode is lower than that of direct measurement, it provides basic protection in sensor failure conditions, preventing system failure caused by a single point of sensor failure and ensuring the basic availability of the vehicle in sensor failure states.

[0052] Step S102: After receiving the active heating request sent by the front motor control unit, the vehicle control unit assesses the status of the vehicle battery pack and determines whether heating is allowed. If allowed, it sends an active heating permission command to the front motor control unit.

[0053] In this embodiment, after receiving the active heating request signal from the FMCU, the HCU needs to assess the vehicle battery pack status to determine whether heating is permitted. Specifically, the assessment logic includes the following three conditions, all of which must be met simultaneously for heating to be permitted: (1) Battery pack state of charge (SOC) is higher than the set lower limit: The HCU reads the battery pack SOC calculated by the BMS through the CAN bus and determines whether the SOC is higher than the set value, such as 15%. If the SOC is lower than 15%, the battery pack has insufficient remaining power and active heating is not allowed to ensure the basic driving needs of the vehicle and the safety of the battery pack.

[0054] (2) Battery pack temperature is higher than the set lower limit: The HCU reads the battery pack temperature calculated by the BMS through the CAN bus and determines whether the battery pack temperature is higher than the set value, such as -20°C. If the battery pack temperature is lower than -20°C, the discharge capacity of the battery pack is severely limited, and active heating is not allowed to avoid damage caused by over-discharge of the battery pack.

[0055] (3) The current maximum allowable continuous discharge power calculated by the BMS is higher than the minimum power required for active heating: The HCU reads the current maximum allowable continuous discharge power calculated by the BMS through the CAN bus and determines whether the power is higher than the minimum power required for active heating (approximately 5 kW). If the current maximum allowable continuous discharge power is lower than 5 kW, the battery pack cannot provide sufficient power to support active heating, and active heating is not allowed.

[0056] For example, in a typical scenario where the ambient temperature is -18°C, the battery pack SOC is 65%, the battery pack temperature is -18°C, and the current maximum allowable continuous discharge power calculated by the BMS is 50 kW, all three conditions are met, and the HCU determines that heating is allowed.

[0057] By simultaneously evaluating three conditions—battery pack state of charge (SOC), battery pack temperature, and maximum permissible discharge power—the vehicle control unit enables coordinated control of active heating and vehicle energy flow management, ensuring that active heating does not affect battery pack safety or vehicle range. When the battery pack SOC is below 15%, the battery pack temperature is below -20°C, and the current maximum permissible continuous discharge power is below 5kW, the vehicle control unit rejects active heating requests, avoiding safety hazards caused by excessive battery pack discharge. Simultaneously, the vehicle control unit dynamically adjusts the maximum permissible heating power limit based on the battery pack status and vehicle energy flow requirements, achieving coordinated optimization of active heating power and vehicle energy flow, ensuring that active heating does not affect normal driving needs and driving range.

[0058] Furthermore, if heating is deemed permissible, the HCU sends an active heating permission command HCU_FMCU Requested State=Activeheat to the FMCU via the CAN bus. This command instructs the FMCU to enter active heating mode and execute the active heating control strategy.

[0059] Correspondingly, if heating is deemed not permitted, the HCU rejects the FMCU's active heating request and does not issue an active heating permission command. At this time, the HCU simultaneously issues a torque limiting command to the FMCU, limiting the transmission's maximum output torque to within 20% of the rated torque (e.g., if the rated torque is 300 Nm, then limit it to 60 Nm) to protect the transmission from damage under poor lubrication conditions. Simultaneously, the HCU sends a "Transmission low temperature protection, please drive cautiously" warning to the instrument panel, advising the driver to reduce speed (ideally below 30 km / h). The FMCU resends the active heating request to the HCU after a 30-second interval until the HCU determines that heating is permitted or triggers a timeout fault warning.

[0060] It should be noted that the torque limitation in the rejection scenario is triggered when the FMCU issues an active heating request, limiting the torque regardless of whether the HCU approves it, to ensure the safety of the transmission under poor lubrication conditions. When heating is approved, the torque limitation ratio is adjusted to 30% of the rated torque (for example, if the rated torque is 300 Nm, it is limited to 90 Nm) to balance heating and drive requirements.

[0061] Furthermore, after receiving the active heating permission command, the front motor control unit activates the active heating mode and sends a feedback. Upon receiving the active heating mode activation signal from the front motor control unit, the vehicle control unit then sends the maximum permissible heating power limit, HCU_FMCU Max ActiveheatPwr, to the front motor control unit. This power limit is calculated by the HCU based on the current battery pack status and the vehicle's energy flow management strategy, and is expressed in kW. In this embodiment, the maximum permissible heating power limit is set to 10 kW.

[0062] Step S102 solves the problem in the prior art that active heating cannot be flexibly controlled according to the battery pack status, realizes intelligent start of active heating mode and optimized management of vehicle energy flow, and ensures the safety of battery pack and the reliability of vehicle.

[0063] As one implementation method, when the vehicle control unit evaluates that the battery pack condition does not meet the requirements and rejects the active heating request, the front motor control unit resends the active heating request to the vehicle control unit after a set time interval, and the vehicle control unit maintains the limitation on the maximum output torque of the transmission during this period.

[0064] In this embodiment, if the HCU assesses that the battery pack status does not meet the conditions (i.e., any one of the following is not met: SOC is below 15%, battery pack temperature is below -20°C, or current maximum allowable continuous discharge power is below 5 kW), the HCU rejects the FMCU's active heating request.

[0065] After receiving the rejection signal from the HCU, the FMCU resends the active heating request signal FMCU_ActiveheatReq=Request to the HCU after a 30-second interval. The purpose of the retry mechanism is to promptly activate the active heating mode and shorten the lubricating oil heating time after the battery pack status recovers (e.g., SOC recovers to above 15%, battery pack temperature recovers to above -20°C, and the current maximum allowable continuous discharge power recovers to above 5 kW).

[0066] During the rejection period, the HCU maintains a limit on the transmission's maximum output torque, restricting it to within 20% of the rated torque (e.g., 60 Nm if the rated torque is 300 Nm) to protect the transmission from damage under poor lubrication conditions. Simultaneously, the HCU sends a "Transmission Low Temperature Protection, Drive with Caution" warning to the instrument panel, advising the driver to reduce speed (ideally below 30 km / h).

[0067] It should be noted that the torque limiting in the rejection scenario is triggered when the FMCU issues an active heating request, limiting torque regardless of whether the HCU approves it, to ensure the safety of the transmission under poor lubrication conditions. Only after the HCU approves heating can the torque limiting ratio be adjusted to 30% of the rated torque to balance heating and drive requirements.

[0068] The aforementioned torque limiting protection mechanism triggers torque limiting upon receiving an active heating request. Regardless of whether the vehicle control unit approves heating, it limits the maximum output torque of the transmission, effectively protecting transmission components in poorly lubricated conditions and preventing excessive wear on gear pairs and bearings during cold starts. In heating-rejected scenarios, the maximum output torque of the transmission is limited to within 20% of the rated torque; in heating-approved scenarios, the maximum output torque is limited to within 30% of the rated torque. This reasonable torque limiting ratio setting protects transmission components while meeting the vehicle's basic driving needs, achieving a balance between protection and performance. Simultaneously, the instrument panel prompts the driver to reduce speed (recommended speed below 30 km / h), further ensuring safety during cold starts.

[0069] The above method solves the problem in the prior art where the lubricating oil cannot be retried after the active heating request is rejected, resulting in the lubricating oil remaining at a low temperature for a long time. It realizes the timed retry of active heating requests and continuous protection of transmission output torque, thereby improving the reliability of the whole vehicle in low temperature environment.

[0070] As another implementation method, if the front motor control unit continuously sends active heating requests for a set period of time without obtaining permission, a fault warning is triggered. This method solves the problem in existing technologies where the driver is not promptly alerted when an active heating request is not approved for an extended period, enabling timely triggering of fault warnings and improving overall vehicle safety and user experience.

[0071] Step S103: The front motor control unit performs torque control within the maximum allowable power limit, while regulating the motor and inverter to increase the heat generation power to heat the lubricating oil, and providing real-time feedback on the actual heating power.

[0072] In this embodiment, after receiving the maximum allowable heating power limit and active heating permission command from the HCU, the FMCU enters the active heating mode and executes the following control strategy: (1) Normal torque control: Based on the torque requirements issued by the HCU, the FMCU controls the drive motor to output the required torque through the FOC vector control algorithm to meet the vehicle's driving needs. In active heating mode, the FMCU maintains the q-axis current to meet the torque requirements, ensuring the normal operation of the drive motor and not affecting the vehicle's driving performance.

[0073] (2) Regulating the motor to increase heat dissipation power: The FMCU increases the copper losses of the generator and drive motor by injecting d-axis excitation current into them, thus converting electrical energy into heat energy. The d-axis excitation current is a magnetizing current component and does not generate effective torque, but it increases the current in the stator windings of the motor, thereby significantly increasing the copper losses (I²R) and converting electrical energy into heat energy. As one implementation method, considering that different motors have different currents, the generator d-axis current and drive motor d-axis current values ​​can be obtained through bench calibration, which can further determine the total copper loss power.

[0074] It's important to note that the fundamental difference between d-axis current injection and existing stalled operation is that in stalled operation, the motor rotor is forcibly locked and cannot rotate, placing the motor under maximum thermal stress, which can easily lead to overheating and damage. However, with d-axis current injection, the motor rotor can rotate freely, power is controlled, and the motor's thermal stress remains within a safe range, preventing damage. Furthermore, when the motor is rotating, iron losses (mainly hysteresis and eddy current losses) increase, further enhancing heat generation. In this embodiment, when the motor speed is 0, the iron loss is primarily hysteresis, approximately 10% of the rated iron loss.

[0075] (3) Adjusting the inverter to increase heat generation power: The FMCU can also increase the inverter's switching losses by adjusting the inverter's PWM switching frequency, thereby converting electrical energy into heat energy. In normal operation mode, the inverter's PWM switching frequency is set to 10kHz, and the switching loss is about 500W; in active heating mode, the FMCU increases the PWM switching frequency to 15~20 kHz, and the switching loss increases to about 1000W.

[0076] By employing a dual heating method of d-axis excitation current injection and inverter PWM switching frequency adjustment, this solution fully utilizes motor copper losses and inverter switching losses, achieving a total heating power of 6-9 kW. With high heating efficiency, it can raise the lubricating oil temperature from -15°C to -5°C within 3-5 minutes, meeting the rapid lubrication requirements for low-temperature starts. Compared to existing electric heater solutions (heating power approximately 1-2 kW, heating time approximately 15-20 minutes), this solution improves heating efficiency by approximately 3-5 times, significantly shortening the low-temperature start-up waiting time and enhancing the user experience. Even in extreme low-temperature environments (ambient temperature below -25°C), this solution can still complete heating within 10 minutes, ensuring reliable vehicle starts in extreme low-temperature conditions.

[0077] (4) Real-time feedback of actual heating power: The FMCU collects the input power of the generator and drive motor in real time through current and voltage sensors, calculates the actual heating power, and feeds back the actual heating power signal FMCU_Activeheat PwrAct to the HCU via the CAN bus. The HCU can dynamically adjust the maximum allowable heating power limit according to the actual heating power to achieve optimized management of the vehicle's energy flow.

[0078] As a further implementation, based on increasing the heat dissipation power, a heat conduction path is designed so that the heat generated by the motor and inverter can be conducted to the lubricating oil through the following paths: Path 1: Direct contact heat exchange. The lubricating oil flows directly through the motor stator cooling oil channels, directly contacting the stator surface for heat exchange. Preferably, the heat exchange power of this path can be calculated according to Newton's law of cooling.

[0079] Path 2: Natural convection acceleration. The rotation of the motor rotor drives the lubricating oil to form natural convection inside the gearbox, accelerating heat transfer. Preferably, the heat transfer power of this path can be calculated based on the natural convection heat transfer coefficient.

[0080] The total heat transfer power of the above path is matched with the total heat generation power generated by d-axis current injection and PWM frequency adjustment, which can achieve efficient heat transfer.

[0081] Step S103 solves the problem that the existing motor and inverter in the hybrid transmission assembly cannot be used as a heating source in the prior art. It enables active heating of lubricating oil without adding a mechanical oil pump, thereby improving the fluidity of the lubricating oil and ensuring the normal operation of the electronic oil pump.

[0082] Step S104: When the lubricating oil temperature reaches the second temperature threshold, the front motor control unit sends a request to exit active heating to the vehicle control unit, and performs normal torque control after exiting the active heating mode.

[0083] In this embodiment, the FMCU continuously monitors the lubricating oil temperature in active heating mode. When the lubricating oil temperature reaches the second temperature threshold, it is determined that the lubricating oil fluidity has been restored, the electronic oil pump can work normally, and active heating is no longer required.

[0084] Specifically, the second temperature threshold is the lubricating oil temperature threshold for exiting the active heating mode. In this embodiment, the second temperature threshold is set to -5℃. When the FMCU detects that the lubricating oil temperature reaches -5℃, it sends an active heating exit request signal FMCU_ActiveheatReq=No Request to the HCU via the CAN bus.

[0085] Upon receiving the request to disengage active heating, the HCU sends a disengagement permission command to the forward motor control unit, releasing the limitation on the transmission's output torque and restoring the transmission's maximum output torque to its rated torque (e.g., if the rated torque is 300 Nm, then it is restored to 300 Nm). Simultaneously, the HCU sends a command to the instrument panel to turn off the "Transmission Warming Up" indicator, notifying the driver that the transmission has completed warm-up and is ready for normal driving.

[0086] After receiving the active heating exit permission command from the HCU, the front motor control unit exits the active heating mode and executes normal speed drive control, that is, the motor switches from active heating mode back to normal drive mode or generator mode. At this time, the FMCU stops injecting d-axis excitation current into the motor and stops adjusting the inverter's PWM switching frequency, and the heat dissipation power of the motor and inverter returns to normal levels.

[0087] It should be noted that the setting of the second temperature threshold needs to comprehensively consider the flow properties of the lubricating oil, the delivery capacity of the electronic oil pump, and the driving requirements of the entire vehicle. In this embodiment, the range of the second temperature threshold is -10℃ to 0℃, which can be adjusted according to different lubricating oil types and the performance of the electronic oil pump.

[0088] Step S104 solves the problem of energy waste caused by the inability to exit the active heating mode in time in the existing technology, and realizes the intelligent exit of the active heating mode and the optimized management of the vehicle's energy flow, thereby improving the energy efficiency of the vehicle and the driving experience.

[0089] As a further implementation, the method proposed in this embodiment also includes: Step S105: After exiting the active heating mode, the front motor control unit controls the electronic oil pump to start, establishes lubricating oil circulation, and provides lubrication and cooling for the gear pair, bearings and motor.

[0090] In this embodiment, after exiting the active heating mode, the FMCU controls the electronic oil pump to start. The electronic oil pump is powered by a 12V auxiliary battery, with a rated flow rate of 15 L / min and a maximum operating pressure of 8 bar. After starting, the electronic oil pump draws lubricating oil from the transmission oil pan and delivers it through oil passages to the lubrication points of the gear pairs, bearings, and motor, establishing a lubricating oil circulation. The lubricating oil circulation path is as follows: (1) Gear pair lubrication: Lubricating oil is sprayed onto the gear meshing surface through the gear lubrication oil passage to form an oil film, reducing friction and wear during gear meshing.

[0091] (2) Bearing lubrication: Lubricating oil flows through the bearing lubrication channel and passes through the inner and outer rings of the bearing to form an oil film, reducing friction and wear when the bearing is rolling.

[0092] (3) Motor cooling: Lubricating oil flows through the motor cooling oil passage, across the surface of the motor rotor and the stator winding, carrying away the heat generated during motor operation and keeping the motor within a suitable operating temperature range.

[0093] After lubrication and cooling, the lubricating oil flows back to the transmission oil pan, completing one cycle. The electric oil pump continues to operate, maintaining the circulation of lubricating oil and ensuring reliable lubrication and cooling of gear pairs, bearings, and motors.

[0094] It should be noted that the electronic oil pump does not start in active heating mode to prevent the lubricating oil from losing heat during flow and affecting the heating effect. The electronic oil pump will only start and establish lubricating oil circulation after the active heating mode is exited and the lubricating oil temperature reaches the second temperature threshold.

[0095] Step S105 solves the problem in the prior art that the lubricating oil circulation cannot be established in time after active heating, and realizes the seamless connection between active heating and lubricating oil circulation, ensuring reliable lubrication and cooling of gear pairs, bearings and motors, and improving the reliability and service life of hybrid transmission.

[0096] After the aforementioned active heating is completed, the electronic oil pump is activated to establish lubricating oil circulation, achieving a seamless connection between active heating and lubricating oil circulation. This forms a complete control closed loop of "low temperature detection → active heating → exiting upon reaching the target → establishing lubrication circulation," ensuring reliable lubrication and cooling of the transmission gear pairs, bearings, and motor after low-temperature starts, thus extending the transmission's service life. In active heating mode, the electronic oil pump does not start, preventing heat loss during lubricating oil flow and ensuring effective heating. Only after the lubricating oil temperature reaches the second temperature threshold (-5°C) and active heating mode is exited can the electronic oil pump activate, establishing lubricating oil circulation to provide lubrication and cooling for the gear pairs, bearings, and motor. Through reasonable control timing design, optimized synergy between active heating and lubricating oil circulation is achieved, ensuring reliable operation of the transmission after low-temperature starts.

[0097] The technical solution provided in this embodiment enables active heating control of lubricating oil in hybrid transmissions at low temperatures. This method utilizes the existing motor and inverter in the hybrid transmission assembly as heating sources, achieving active heating of the lubricating oil without adding a mechanical oil pump. This effectively solves the problem of the inability to deliver lubricating oil using only an electronic oil pump in low-temperature environments, reducing system cost and size, and contributing to vehicle lightweighting. Compared to existing solutions that require adding a mechanical oil pump or electric heater, this solution requires no additional hardware investment. Active heating of the lubricating oil can be achieved simply by controlling the operating state of the motor and inverter through software strategies. This saves on the purchase cost of a mechanical oil pump (typically around 100 RMB / unit), installation space (approximately 1L volume), and weight (approximately 0.5kg), as well as the purchase cost of an electric heater (approximately 100 RMB / unit) and high-voltage power harness costs, resulting in significant cost reduction and lightweighting at the vehicle level.

[0098] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this embodiment.

[0099] It is understandable that the aforementioned beneficial effects are interconnected and synergistic, collectively constituting the overall advantages of this technical solution. By utilizing the existing motor and inverter in the hybrid transmission assembly as heating sources, and combining multiple technical means such as collaborative management by the vehicle control unit, torque limiting protection, timed retry mechanism, timeout fault indication, sensor fault degradation control, and seamless integration with the electronic oil pump, this solution achieves efficient, safe, and reliable active heating control of hybrid transmission lubricating oil in low-temperature environments. It effectively solves the problem that existing technologies cannot deliver lubricating oil using only an electronic oil pump. It has significant advantages in terms of cost, size, heating efficiency, safety, reliability, and driving experience, providing an innovative technical solution for low-temperature lubrication control of hybrid transmissions with a pure electronic oil pump architecture.

[0100] Example 2 This embodiment also provides a hybrid transmission lubricating oil active heating control system, which includes: a lubricating oil temperature sensor, a motor and an inverter, an electronic oil pump, a front motor control unit, and a vehicle control unit; wherein the front motor control unit interacts with the vehicle control unit to realize the above-mentioned hybrid transmission lubricating oil active heating control method.

[0101] In this embodiment, a lubricating oil temperature sensor is used to detect the lubricating oil temperature and feed it back to the front motor control unit; a motor and an inverter are used to increase the heating power to heat the lubricating oil after receiving a heating command from the front motor control unit; and an electronic oil pump is used to establish a lubricating and cooling oil circulation after the lubricating oil temperature reaches a preset range.

[0102] In addition, the front motor control unit is specifically configured to detect the lubricating oil temperature, send active heating requests, control the heating power of the motor and inverter, control the start of the electronic oil pump, retry the active heating request at regular intervals, trigger fault prompts, and switch to degraded control mode when a sensor fails; the vehicle control unit is specifically configured to assess the battery pack status, issue the maximum allowable heating power limit and active heating permission command, control the transmission output torque limit, and maintain the torque limit when the active heating request is rejected.

[0103] Example 3 This embodiment provides a vehicle that includes the above-described active heating control system for hybrid transmission lubricating oil, or performs the above-described active heating control method for hybrid transmission lubricating oil.

[0104] Example 4 This embodiment provides an electronic device, including: a memory for storing executable instructions; and a processor for executing the executable instructions stored in the memory to implement the above-mentioned active heating control method for lubricating oil of hybrid transmissions provided in this embodiment.

[0105] Example 5 This embodiment also provides a computer-readable storage medium storing executable instructions. When the executable instructions are executed by a processor, the processor will execute the above-described active heating control method for lubricating oil in a hybrid transmission provided in this embodiment.

[0106] The steps and methods involved in Embodiments 2 to 5 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0107] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0108] The above description is only a preferred embodiment of the present invention. Although the specific embodiments of the present invention have been described in conjunction with the accompanying drawings, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A method for active heating control of lubricating oil in a hybrid transmission, characterized in that, This is achieved through interaction between the front motor control unit and the vehicle control unit, wherein the front motor control unit is used to perform: After detecting that the vehicle has started and the hybrid transmission assembly is powered on, the lubricating oil temperature is monitored in real time and it is determined whether it is below the first temperature threshold. If so, an active heating request is sent to the vehicle control unit. If an active heating permission command is received, the active heating mode is activated and feedback is provided. Then, within the received maximum allowable power limit, torque control is performed, and the motor and inverter are adjusted to increase the heating power to heat the lubricating oil. The actual heating power is fed back in real time. When the lubricating oil temperature reaches the second temperature threshold, a request to exit the active heating mode is sent to the vehicle control unit. After receiving the exit active heating permission command, the active heating mode is exited and normal torque control is executed.

2. The active heating control method for lubricating oil in a hybrid transmission according to claim 1, characterized in that, The vehicle control unit is used to perform: After receiving the active heating request sent by the front motor control unit, the vehicle battery pack status is evaluated to determine whether heating is allowed. If it is allowed, an active heating permission command is sent to the front motor control unit. After receiving the active heating mode start signal from the front motor control unit, the maximum allowable heating power limit is sent to the front motor control unit. Upon receiving the request to exit active heating from the front motor control unit, the system issues an exit active heating permission command to the front motor control unit.

3. The active heating control method for lubricating oil in a hybrid transmission according to claim 2, characterized in that, The vehicle control unit assesses the battery pack status based on the battery pack's state of charge, temperature, and maximum permissible discharge power to determine whether heating is permissible, including: If the following conditions are met simultaneously: the battery pack state of charge is higher than the set lower limit, the battery pack temperature is higher than the set lower limit, and the current maximum allowable continuous discharge power calculated by the BMS is higher than the minimum power required for active heating, then heating is allowed and an active heating mode command is issued; otherwise, heating is not allowed.

4. The active heating control method for lubricating oil in a hybrid transmission according to claim 2, characterized in that, The vehicle control unit sends a torque limiting command to the front motor control unit to limit the maximum output torque of the transmission to within a preset ratio of the rated torque, so as to perform torque control during the lubricating oil heating process. During the lubricating oil heating process, the front motor control unit detects the lubricating oil temperature in real time and determines whether the second temperature threshold has been reached. If so, it sends a request to exit active heating to the vehicle control unit. After receiving the request to deactivate active heating, the vehicle control unit releases the limitation on the transmission output torque.

5. The active heating control method for lubricating oil in a hybrid transmission according to claim 2, characterized in that, When the vehicle control unit evaluates that the battery pack condition does not meet the requirements and rejects the active heating request, the front motor control unit resends the active heating request to the vehicle control unit after a set time interval, and the vehicle control unit maintains the limit on the maximum output torque of the transmission during the resending period.

6. The active heating control method for lubricating oil in a hybrid transmission according to claim 5, characterized in that, If the front motor control unit continuously sends active heating requests for a period of time exceeding the set time and still fails to obtain permission, a fault prompt will be triggered.

7. The active heating control method for lubricating oil in a hybrid transmission according to claim 1, characterized in that, Increase heat dissipation power by controlling the operating status of the motor and inverter, including: Increasing motor copper losses by injecting d-axis excitation current into the motor; Increase inverter switching losses by adjusting the inverter's PWM switching frequency.

8. The active heating control method for lubricating oil in a hybrid transmission according to claim 1, characterized in that, When the lubricating oil temperature sensor malfunctions, the front motor control unit switches to degraded control mode and calculates the lubricating oil temperature based on the ambient temperature detected by the ambient temperature sensor and the vehicle's parking time. When the calculated lubricating oil temperature is lower than the first temperature threshold, an active heating request is sent to the vehicle control unit.

9. The active heating control method for lubricating oil in a hybrid transmission according to claim 1, characterized in that, After exiting the active heating mode, the front motor control unit controls the electronic oil pump to start, establishing a lubricating oil circulation to provide lubrication and cooling for the gear pair, bearings, and motor.

10. A hybrid transmission lubricating oil active heating control system, characterized in that, include: Lubricating oil temperature sensor, motor and inverter, electronic oil pump, front motor control unit, vehicle control unit; The lubricating oil temperature sensor is used to detect the lubricating oil temperature and feed it back to the front motor control unit; The motor and inverter are used to increase the heating power to heat the lubricating oil after receiving a heating command from the front motor control unit; The electronic oil pump is used to establish a lubricating and cooling oil circulation after the lubricating oil temperature reaches a preset range; The front motor control unit interacts with the vehicle control unit to implement the active heating control method for hybrid transmission lubricating oil as described in any one of claims 1-9.

11. A vehicle, characterized in that, Includes the active heating control system for hybrid transmission lubricating oil as described in claim 10, or performs the active heating control method for hybrid transmission lubricating oil as described in any one of claims 1-9.

12. An electronic device, characterized in that, include: Memory, used to store executable instructions; The processor, when executing executable instructions stored in the memory, implements the active heating control method for lubricating oil of a hybrid transmission as described in any one of claims 1-9.

13. A computer-readable storage medium, characterized in that, The device stores executable instructions for causing a processor to execute the executable instructions to implement the active heating control method for lubricating oil of a hybrid transmission as described in any one of claims 1-9.

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