A method of overheat control for a transmission

Abstract

A kind of overheat control method of transmission, by real-time monitoring the oil temperature of transmission and the water temperature of radiator, including respectively enabling or disabling transmission overheat protection mode with different threshold, avoid the emergence of cold and hot impact while protecting transmission, distinguish between regular overheat protection and forced overheat protection, in regular overheat protection, set water temperature threshold protection and cooling performance gradually amplifies two layers of logic, maximum limit to ensure the reliability of engine and transmission.

Description

Technical Field

[0001] This invention relates to the field of automotive safety technology, and in particular to a device for preventing suffocation inside a vehicle. Background Technology

[0002] Transmission overheat protection, as an auxiliary requirement of the cooling system, is generally defined by a single threshold. For example, if the oil temperature exceeds 80°C, the temperature control module is required to be 100% open to provide heat dissipation. However, in actual operation, such as in cold regions, the water temperature rarely reaches high values ​​due to the long-term heat consumption of heating, and the radiator is often not turned on, resulting in the transmission not being cooled for extended periods. However, under conditions such as long inclines and traffic jams, there is still a risk of clutch slippage, causing the oil temperature to rise rapidly. Therefore, a situation may exist where the water temperature is low and the oil temperature is high. If, in this case, the transmission overheat protection triggers the temperature control module to fully open all at once due to the oil temperature exceeding the threshold, it can easily lead to a sudden and significant drop in water temperature. After the oil temperature also drops rapidly and significantly, the transmission overheat protection is deactivated, and the temperature control module returns to normal control, shutting off the radiator. The water and oil temperatures then re-enter a temperature rise cycle, repeating this process repeatedly, creating thermal shocks that are extremely detrimental to the lifespan and reliability of the engine and transmission.

[0003] To address this thermal shock, the most common solution currently available is to add an electronic water pump inside the transmission circuit. When the thermostat is not open and there is no water flow inside the transmission oil cooler, the electronic water pump is activated to achieve self-circulation within the transmission. However, adding an electronic water pump will significantly increase costs, system architecture complexity, and energy consumption, making it not cost-effective. Summary of the Invention

[0004] In view of this, the present invention provides an overheat control method for a transmission that protects the transmission from thermal shock.

[0005] The overheat control method for the transmission of the present invention includes the following steps:

[0006] Step S1: The EMS performs fault detection on the cooling system. If a fault is detected, the EMS will issue an alarm and limit the engine speed and torque. The EMS will input the maximum opening signal to the temperature control module. If no fault is detected, proceed to step S2.

[0007] Step S2: The EMS performs fault detection on the water temperature sensor. If a fault is detected, the EMS will alarm, input the maximum flow signal to the electronic water pump, and fully open the temperature control module. If no fault is detected, proceed to step S3.

[0008] Step S3: The EMS reads the current water temperature and determines whether the engine is in operation. If the engine is in operation, it calculates the required opening degree of the first temperature control module and the required speed of the first cooling fan based on the water temperature.

[0009] Step S4: EMS monitors the transmission oil temperature:

[0010] If the oil temperature exceeds the first oil temperature overheating threshold and the water temperature exceeds the first water temperature overheating threshold, the temperature control module enters the transmission overheat protection mode.

[0011] When the temperature control module is in the transmission overheat protection mode, if the oil temperature is lower than the first oil temperature overheat hysteresis threshold or the water temperature is lower than the first water temperature overheat hysteresis threshold, the temperature control module will exit the transmission overheat protection mode.

[0012] Furthermore, in step S4, if the oil temperature exceeds the second oil temperature overheating threshold, the temperature control module enters the transmission overheat protection mode.

[0013] When the temperature control module is in the transmission overheat protection mode, if the oil temperature is lower than the second oil temperature overheat hysteresis threshold, the temperature control module will exit the transmission overheat protection mode.

[0014] Furthermore, the overheat control method for the transmission also includes the following steps:

[0015] Step S5: EMS monitors the transmission oil temperature:

[0016] If the oil temperature exceeds the third oil temperature overheating threshold and the water temperature exceeds the second water temperature overheating threshold, the cooling fan will enter the transmission overheat protection mode.

[0017] When the cooling fan is in the transmission overheat protection mode, if the oil temperature is lower than the third oil temperature overheat hysteresis threshold or the water temperature is lower than the second water temperature hysteresis threshold, the cooling fan will exit the transmission overheat protection mode.

[0018] Furthermore, in step S5, if the oil temperature exceeds the fourth oil temperature overheating threshold, the cooling fan enters the transmission overheat protection mode.

[0019] When the cooling fan is in the transmission overheat protection mode, if the oil temperature is lower than the fourth oil temperature overheat hysteresis threshold, the cooling fan will exit the transmission overheat protection mode.

[0020] Furthermore, the required opening degree of the first temperature control module and the required speed of the first cooling fan in step S3 are both calibration values ​​obtained by looking up a table based on the current engine speed and load.

[0021] Furthermore, in step S4, the first oil temperature overheat threshold, the first water temperature overheat threshold, the first oil temperature overheat hysteresis threshold, the first water temperature overheat hysteresis threshold, the second oil temperature overheat threshold, and the second oil temperature overheat hysteresis threshold are all calibrated values. The first oil temperature overheat threshold is greater than the first oil temperature overheat hysteresis threshold, the first water temperature overheat threshold is greater than the first water temperature overheat hysteresis threshold, the second oil temperature overheat threshold is greater than the second oil temperature overheat hysteresis threshold, and the second oil temperature overheat threshold is significantly higher than the first oil temperature overheat threshold. Similarly, in step S5, the third oil temperature overheat threshold, the second water temperature overheat threshold, the third oil temperature overheat hysteresis threshold, the second water temperature hysteresis threshold, the fourth oil temperature overheat threshold, and the fourth oil temperature overheat hysteresis threshold are all calibrated values. The third oil temperature overheat threshold is greater than the third oil temperature overheat hysteresis threshold, the second water temperature overheat threshold is greater than the second water temperature hysteresis threshold, the fourth oil temperature overheat threshold is greater than the fourth oil temperature overheat hysteresis threshold, and the fourth oil temperature overheat threshold is significantly higher than the third oil temperature overheat threshold.

[0022] Furthermore, the overheat control method for the transmission also includes step S6:

[0023] In the overheat protection mode of the transmission:

[0024] The final opening degree of the temperature control module is obtained by comparing the required opening degree of the first temperature control module and the required opening degree of the second temperature control module, and taking the larger one.

[0025] The final output speed of the cooling fan is obtained by comparing the required speed of the first cooling fan and the required speed of the second cooling fan, and taking the larger one.

[0026] Furthermore, in the overheat protection mode of the transmission, the opening degree TMM_pos2 of the second temperature control module is calculated by looking up the opening degree TMM_pos2ini and the temperature control module correction factor cof1, i.e., equation (1):

[0027] TMM_pos2=TMM_pos2ini*cof1.

[0028] Furthermore, the lookup requirement of the temperature control module is obtained by looking up the current oil temperature and water temperature, and the correction factor of the temperature control module is obtained by looking up the vehicle speed and ambient temperature.

[0029] Furthermore, in the overheat protection mode of the transmission, the required speed of the second cooling fan, Fan_spd2, is calculated by looking up the required speed, Fan_spd2ini, and the cooling fan correction factor, cof2, as shown in equation (2):

[0030] Fan_spd2=Fan_spd2ini*cof2.

[0031] Furthermore, the required rotational speed of the cooling fan is obtained by looking up the table based on the current oil temperature and water temperature, and the cooling fan correction factor is obtained by looking up the table based on the vehicle speed and ambient temperature.

[0032] Furthermore, the overheat control method for the transmission also includes step S7:

[0033] EMS monitors the transmission oil temperature:

[0034] If the oil temperature does not exceed the first oil temperature overheating threshold, the temperature control module will eventually output the required opening degree of the first temperature control module, and the cooling fan will eventually output the required speed of the first cooling fan.

[0035] The overheat control method for the transmission of this invention distinguishes between conventional overheat protection and forced overheat protection. In conventional overheat protection, two layers of logic are set: water temperature threshold protection and gradual amplification of cooling performance, effectively preventing the engine from experiencing prolonged thermal shock. Compared to conventional vehicle systems, this invention can effectively protect the transmission from overheating while achieving engine fuel saving and emission reduction. Furthermore, it ensures that the engine is not subjected to prolonged thermal shock, maximizing the reliability of both the engine and transmission. This invention expands the application of the temperature control module, taking into account both the cooling requirements of the transmission oil cooler and the overheat protection requirements in the context of an electrified cooling system, avoiding the need for a new electronic water pump and reducing costs.

[0036] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the cooling system on which the present invention is based.

[0038] Figure 2 This is a schematic diagram of the overheat control method for a transmission provided by the present invention. Detailed Implementation

[0039] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0040] Please see Figure 1The overheat control method for the transmission of the present invention is based on an engine system that includes at least an engine, a transmission, a turbocharger, an expansion tank, and a cooling system. The cooling system includes at least an electric water pump, an oil cooler, a radiator, a water temperature sensor, a transmission oil temperature sensor, and a temperature control module. In the figure, the solid line represents the flow direction of the cooling water circulation, and the dashed line represents the possible flow direction of the cooling water circulation. Whether the dashed line exists depends on the specific circumstances of the engine cooling system. Figure 1 This is merely a simple example of an engine cooling system to which this invention applies.

[0041] The input signals of this invention include water temperature T_clt, engine speed engspd, load, oil temperature T_oil, vehicle speed V_spd, and ambient temperature T_amb, which come from the water temperature sensor, engine oil temperature sensor, and vehicle network, respectively. The output signals are the final temperature control module opening degree TMM_posfinal and the final cooling fan speed Fan_posfinal, or the first temperature control module required opening degree TMM_pos1 and the first cooling fan required speed Fan_spd1.

[0042] Please refer to the following: Figure 2 The overheat control method for the transmission of the present invention includes the following steps:

[0043] Step S1: The EMS performs fault detection on the cooling system. If a fault is detected, the EMS will issue an alarm and limit the engine speed and torque. The EMS will input the maximum opening signal to the temperature control module. If no fault is detected, proceed to step S2.

[0044] Specifically, after the vehicle is powered on, the Engine Control System (EMS) begins a self-test, which primarily checks the status of the temperature control module. After starting, the temperature control module performs a self-learning process for the fully closed position. If it becomes stuck in the fully closed position, the entire system will be shut down, resulting in a loss of coolant flow. This could lead to engine overheating. Furthermore, since the internal hot water will not flow to the outside, external sensors cannot accurately detect the internal hot water and cannot effectively monitor it. Therefore, in the event of a stuck or other fault, the engine will be required to limit its speed and torque to protect it.

[0045] Step S2: The EMS performs fault detection on the water temperature sensor. If a fault is detected, the EMS will alarm and input the maximum flow signal to the electronic water pump. At the same time, the temperature control module will be fully turned on to prevent the engine from overheating. If no fault is detected, proceed to step S3.

[0046] Specifically, after the temperature control module completes its self-test and is normal, it begins to determine whether the water temperature sensor is faulty. If the water temperature sensor is faulty, the engine controller will issue an alarm and output a signal to open the temperature control module to full opening, thus fully releasing the cooling system's capacity and preventing the engine from overheating.

[0047] Step S3: The EMS reads the current water temperature T_clt and determines whether the engine is in operation. If the engine is in operation, the required opening degree TMM_pos1 of the first temperature control module and the required speed Fan_spd1 of the first radiator fan are calculated based on the water temperature T_clt.

[0048] Specifically, the EMS can directly read the current water temperature T_clt from the water temperature sensor. When determining whether the engine is in operation, it only needs to read the engine speed engspd. If this variable is not zero, it indicates that the engine is running. Then, based on the water temperature T_clt and the existing relevant control strategies inside the engine, that is, the normal operation strategy of the cooling system, it calculates the required opening degree TMM_pos1 of the first temperature control module and the required speed of the first radiator fan Fan_spd1 and outputs them. In this embodiment, the required opening degree TMM_pos1 of the first temperature control module and the required speed of the first radiator fan Fan_spd1 are both calibration values ​​obtained by looking up tables based on the current engine speed engspd and load.

[0049] Step S4: EMS monitors the transmission oil temperature T_oil:

[0050] If the oil temperature T_oil exceeds the first oil temperature overheating threshold T_oil_th1 and the water temperature T_clt exceeds the first water temperature overheating threshold T_clt_th1, the temperature control module enters the transmission overheat protection mode, and the flag bit Bit1_TMM1 = 1.

[0051] When the temperature control module is in the transmission overheat protection mode, if the oil temperature T_oil is lower than the first oil temperature overheat hysteresis threshold T_oil_hys1 or the water temperature T_clt is lower than the first water temperature overheat hysteresis threshold T_clt_hys1, the temperature control module exits the transmission overheat protection mode and sets the flag bit Bit1_TMM1 = 0.

[0052] If the oil temperature T_oil exceeds the second oil temperature overheating threshold T_oil_th2, the temperature control module enters the transmission overheat protection mode, and the flag bit Bit2_TMM2 is set to 1;

[0053] When the temperature control module is in the transmission overheat protection mode, if the oil temperature T_oil is lower than the second oil temperature overheat hysteresis threshold T_oil_hys2, the temperature control module exits the transmission overheat protection mode and sets the flag bit2_TMM2 = 0.

[0054] Step S5: EMS monitors the transmission oil temperature T_oil:

[0055] If the oil temperature T_oil exceeds the third oil temperature overheating threshold T_oil_th3 and the water temperature T_clt exceeds the second water temperature overheating threshold T_clt_th2, the cooling fan enters the transmission overheat protection mode. Set the flag bit Bit1_fan1 = 1.

[0056] When the cooling fan is in the transmission overheat protection mode, if the oil temperature T_oil is lower than the third oil temperature overheat hysteresis threshold T_oil_hys3 or the water temperature T_clt is lower than the second water temperature hysteresis threshold T_clt_hys2, the cooling fan will exit the transmission overheat protection mode, and the flag bit Bit1_fan1 = 0.

[0057] If the oil temperature T_oil exceeds the fourth oil temperature overheating threshold T_oil_th4, the cooling fan enters the transmission overheat protection mode, and the flag bit Bit2_fan2 = 1.

[0058] When the cooling fan is in the transmission overheat protection mode, if the oil temperature T_oil is lower than the fourth oil temperature overheat hysteresis threshold T_oil_hys4, the cooling fan will exit the transmission overheat protection mode, and the flag bit Bit2_fan2 = 0.

[0059] Specifically, this invention divides the overheat protection requirements of the transmission into two levels. One is ordinary overheat prevention protection, which gradually releases cooling performance to avoid thermal shock. The other is forced overheat protection under extreme conditions, where the radiator branch is forcibly opened when the transmission is about to fail, ensuring the safe and reliable overheat protection of the transmission. The logic is as follows:

[0060] The EMS obtains the transmission oil temperature T_oil through the vehicle network and compares it with the preset oil protection threshold, namely the first oil temperature overheating threshold T_oil_th1. If the oil temperature T_oil has exceeded the first oil temperature overheating threshold T_oil_th1, the collected coolant temperature T_clt is then compared with the preset allowable coolant temperature threshold, namely the first coolant temperature overheating threshold T_clt_th1. If the coolant temperature T_clt has also exceeded the first coolant temperature overheating threshold T_clt_th1, the temperature control module is allowed to enter the transmission overheat protection mode, and the flag bit Bit1_TMM1 is set to 1.

[0061] In the transmission overheat protection mode, when the oil temperature T_oil is lower than the first oil temperature overheat hysteresis threshold T_oil_hys1 or the water temperature T_clt is lower than the first water temperature overheat hysteresis threshold T_clt_hys1, the transmission overheat protection mode is exited, and the flag bit Bit1_TMM1 is set to 0.

[0062] Specifically, the overheat control method for the transmission of the present invention, in addition to determining whether the oil temperature T_oil exceeds the limit, also determines the water temperature T_clt. This is to provide a "first layer of protection" for the water temperature T_clt in the context of "thermal shock". In this embodiment, the first oil temperature overheat threshold T_oil_th1 is one of the overheat protection thresholds used for the "first layer of protection". When the water temperature T_clt is at the normal level of 95°C, and the oil temperature T_oil exceeds the threshold to 90°C, the temperature control module is requested to open the radiator branch to start cooling. The water temperature T_clt then drops sharply. In cold operating conditions, the water temperature T_clt will drop to about 50-60°C in a short time, causing temperature fluctuations. However, after using the first water temperature overheat hysteresis threshold T_clt_hys1 to provide the "first layer of protection" for the water temperature T_clt, the temperature drop stops at the position of the "first water temperature overheat hysteresis threshold T_clt_hys1", that is, at 85°C. Obviously, the overheat control method of the transmission of the present invention can protect the transmission from overheating while ensuring that the water temperature T_clt fluctuates within a small range, namely 85-100℃, rather than oscillating significantly, and the phenomenon of thermal shock will not occur.

[0063] It is readily understood that the present invention avoids thermal shock through the aforementioned general overheating prevention protection in order to extend and protect the service life and reliability of the engine and transmission, ensuring long-term engine use. However, for occasional, short-term, and severe transmission overheating events, a transmission overheating protection mode is also urgently needed. The aforementioned "first layer of protection," namely general overheating prevention protection, is insufficient to cover such emergency overheating events. Therefore, a "second layer of protection," namely mandatory overheating protection, is also required, with the following logic:

[0064] When the transmission oil temperature T_oil exceeds the second oil temperature overheating threshold T_oil_th2, the temperature control module directly enters the transmission overheat protection mode, and at this time the flag bit Bit2_TMM2 is set to 1;

[0065] When the oil temperature T_oil is lower than the second oil temperature overheat hysteresis threshold T_oil_hys2, the transmission overheat protection mode is exited, and the flag bit Bit2_TMM2 is set to 0.

[0066] Specifically, under the judgment logic of "second layer protection", the second oil temperature overheating threshold T_oil_th2 is the forced overheating protection threshold used for "second layer protection". Once the oil temperature T_oil exceeds this value, the water temperature T_clt is not considered, nor is the above-mentioned general overheating prevention protection, and the transmission overheating protection mode is directly entered. In this embodiment, the first oil temperature overheating threshold T_oil_th1, the first water temperature overheating threshold T_clt_th1, the first oil temperature overheating hysteresis threshold T_oil_hys1, the first water temperature overheating hysteresis threshold T_clt_hys1, the second oil temperature overheating threshold T_oil_th2, and the second oil temperature overheating hysteresis threshold T_oil_hys2 are all calibrated values. The first oil temperature overheating threshold T_oil_th1 is greater than the first oil temperature overheating hysteresis threshold T_oil_hys1, the first water temperature overheating threshold T_clt_th1 is greater than the first water temperature overheating hysteresis threshold T_clt_hys1, the second oil temperature overheating threshold T_oil_th2 is greater than the second oil temperature overheating hysteresis threshold T_oil_hys2, the second oil temperature overheating threshold T_oil_th2 is significantly higher than the first oil temperature overheating threshold T_oil_th1, and the second oil temperature overheating threshold T_oil_th2 is set above 110°C.

[0067] Similarly, the control logic for the cooling fan in step S5 is the same as the control logic for the temperature control module described above, and will not be repeated here. In this embodiment, the third oil temperature overheating threshold T_oil_th3, the second water temperature overheating threshold T_clt_th2, the third oil temperature overheating hysteresis threshold T_oil_hys3, the second water temperature hysteresis threshold T_clt_hys2, the fourth oil temperature overheating threshold T_oil_th4, and the fourth oil temperature overheating hysteresis threshold T_oil_hys4 are all calibrated values. Among them, the third oil temperature overheating threshold T_oil_th3 is greater than the third oil temperature overheating hysteresis threshold T_oil_hys3, the second water temperature overheating threshold T_clt_th2 is greater than the second water temperature hysteresis threshold T_clt_hys2, the fourth oil temperature overheating threshold T_oil_th4 is greater than the fourth oil temperature overheating hysteresis threshold T_oil_hys4, and the fourth oil temperature overheating threshold T_oil_th4 is significantly higher than the third oil temperature overheating threshold T_oil_th3.

[0068] Furthermore, the overheat control method for the transmission of the present invention further includes step S6:

[0069] In the transmission overheat protection mode, the final temperature control module opening degree TMM_posfinal, which is the engine's own requirement, is obtained by comparing the first temperature control module opening degree TMM_pos1 with the transmission's requirement, which is the second temperature control module opening degree TMM_pos2, and taking the larger value. The final cooling fan speed Fan_posfinal, which is the engine's own requirement, is obtained by comparing the first cooling fan speed Fan_spd1 with the transmission's requirement, which is the second cooling fan speed Fan_spd2, and taking the larger value.

[0070] In this embodiment, the required opening degree TMM_pos2 of the second temperature control module is calculated by looking up the required opening degree TMM_pos2ini and the temperature control module correction factor cof1, i.e., equation (1):

[0071] TMM_pos2=TMM_pos2ini*cof1.

[0072] The temperature control module's lookup requirement TMM_pos2ini is obtained by looking up the current oil temperature T_oil and water temperature T_clt, while the temperature control module's correction factor cof1 is obtained by looking up the vehicle speed V_spd and ambient temperature T_amb.

[0073] Similarly, the required speed of the second cooling fan, Fan_spd2, is calculated by looking up the required speed, Fan_spd2ini, and the cooling fan correction factor, cof2, as shown in equation (2):

[0074] Fan_spd2=Fan_spd2ini*cof2.

[0075] Fan_spd2ini is obtained by looking up tables based on the current oil temperature T_oil and water temperature T_clt, while the cooling fan correction factor cof2 is obtained by looking up tables based on the vehicle speed V_spd and ambient temperature T_amb.

[0076] Furthermore, the overheat control method for the transmission of the present invention further includes step S7:

[0077] EMS monitors the transmission oil temperature T_oil:

[0078] If the oil temperature T_oil does not exceed the first oil temperature overheating threshold T_oil_th1, the temperature control module will eventually output the first temperature control module required opening degree TMM_pos1, and the cooling fan will eventually output the first cooling fan required speed Fan_spd1.

[0079] In summary, the overheat control method for the transmission of this invention distinguishes between conventional overheat protection and forced overheat protection. The conventional overheat protection incorporates two layers of logic: water temperature threshold protection and gradual amplification of cooling performance, effectively preventing prolonged thermal shock to the engine. Compared to conventional vehicle systems, this invention effectively protects the transmission from overheating while achieving fuel economy and emission reduction. Furthermore, it ensures the engine is not subjected to prolonged thermal shock, maximizing the reliability of both the engine and transmission. This invention expands the application of the temperature control module, addressing both the cooling requirements of the transmission oil cooler and overheat protection needs within the context of an electrified cooling system, avoiding the need for a new electronic water pump and reducing costs.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for controlling overheating of a transmission, characterized in that: It includes the following steps: Step S1: The EMS performs fault detection on the cooling system. If a fault is detected, the EMS will issue an alarm and limit the engine speed and torque. The EMS will input the maximum opening signal to the temperature control module. If no fault is detected, proceed to step S2. Step S2: The EMS performs fault detection on the water temperature sensor. If a fault is detected, the EMS will alarm, input the maximum flow signal to the electronic water pump, and fully open the temperature control module. If no fault is detected, proceed to step S3. Step S3: The EMS reads the current water temperature and determines whether the engine is in operation. If the engine is in operation, it calculates the required opening degree of the first temperature control module and the required speed of the first cooling fan based on the water temperature. Step S4: EMS monitors the transmission oil temperature: If the oil temperature exceeds the first oil temperature overheating threshold and the water temperature exceeds the first water temperature overheating threshold, the temperature control module enters the transmission overheat protection mode. When the temperature control module is in the transmission overheat protection mode, if the oil temperature is lower than the first oil temperature overheat hysteresis threshold or the water temperature is lower than the first water temperature overheat hysteresis threshold, the temperature control module will exit the transmission overheat protection mode. If the oil temperature exceeds the second oil temperature overheat threshold, the temperature control module enters the transmission overheat protection mode. When the temperature control module is in the transmission overheat protection mode, if the oil temperature is lower than the second oil temperature overheat hysteresis threshold, the temperature control module will exit the transmission overheat protection mode. Step S5: EMS monitors the transmission oil temperature: If the oil temperature exceeds the third oil temperature overheating threshold and the water temperature exceeds the second water temperature overheating threshold, the cooling fan will enter the transmission overheat protection mode. When the cooling fan is in the transmission overheat protection mode, if the oil temperature is lower than the third oil temperature overheat hysteresis threshold or the water temperature is lower than the second water temperature hysteresis threshold, the cooling fan will exit the transmission overheat protection mode.

2. The overheat control method for a transmission according to claim 1, characterized in that: In step S5, if the oil temperature exceeds the fourth oil temperature overheating threshold, the cooling fan enters the transmission overheat protection mode. When the cooling fan is in the transmission overheat protection mode, if the oil temperature is lower than the fourth oil temperature overheat hysteresis threshold, the cooling fan will exit the transmission overheat protection mode.

3. The overheat control method for a transmission according to claim 1, characterized in that: The required opening degree of the first temperature control module and the required speed of the first cooling fan in step S3 are both calibration values ​​obtained by looking up a table based on the current engine speed and load.

4. The overheat control method for a transmission according to claim 2, characterized in that: In step S4, the first oil temperature overheat threshold, the first water temperature overheat threshold, the first oil temperature overheat hysteresis threshold, the first water temperature overheat hysteresis threshold, the second oil temperature overheat threshold, and the second oil temperature overheat hysteresis threshold are all calibrated values. The first oil temperature overheat threshold is greater than the first oil temperature overheat hysteresis threshold, the first water temperature overheat threshold is greater than the first water temperature overheat hysteresis threshold, the second oil temperature overheat threshold is greater than the second oil temperature overheat hysteresis threshold, and the second oil temperature overheat threshold is significantly higher than the first oil temperature overheat threshold. In step S5, the third oil temperature overheat threshold, the second water temperature overheat threshold, the third oil temperature overheat hysteresis threshold, the second water temperature hysteresis threshold, the fourth oil temperature overheat threshold, and the fourth oil temperature overheat hysteresis threshold are all calibrated values. The third oil temperature overheat threshold is greater than the third oil temperature overheat hysteresis threshold, the second water temperature overheat threshold is greater than the second water temperature hysteresis threshold, the fourth oil temperature overheat threshold is greater than the fourth oil temperature overheat hysteresis threshold, and the fourth oil temperature overheat threshold is significantly higher than the third oil temperature overheat threshold.

5. The overheat control method for a transmission according to claim 2, characterized in that: The overheat control method for the transmission also includes step S6: In the overheat protection mode of the transmission: The final opening degree of the temperature control module is obtained by comparing the required opening degree of the first temperature control module and the required opening degree of the second temperature control module, and taking the larger one. The final output speed of the cooling fan is obtained by comparing the required speed of the first cooling fan and the required speed of the second cooling fan, and taking the larger one.

6. The overheat control method for a transmission according to claim 5, characterized in that: In the overheat protection mode of the transmission, the opening degree TMM_pos2 of the second temperature control module is calculated by looking up the opening degree TMM_pos2ini in the table and the temperature control module correction factor cof1, i.e., equation (1): TMM_pos2=TMM_pos2ini*cof1.

7. The overheat control method for a transmission according to claim 6, characterized in that: The temperature control module's lookup requirement is obtained by looking up the current oil temperature and water temperature, and the temperature control module's correction factor is obtained by looking up the vehicle speed and ambient temperature.

8. The overheat control method for a transmission according to claim 7, characterized in that: In the overheat protection mode of the transmission, the required speed of the second cooling fan, Fan_spd2, is calculated by looking up the required speed, Fan_spd2ini, and the cooling fan correction factor, cof2, as shown in equation (2): Fan_spd2=Fan_spd2ini*cof2.

9. The overheat control method for a transmission according to claim 8, characterized in that: The required rotational speed of the cooling fan is obtained by looking up the table based on the current oil temperature and water temperature, and the cooling fan correction factor is obtained by looking up the table based on the vehicle speed and ambient temperature.

10. The overheat control method for a transmission according to claim 9, characterized in that: The overheat control method for the transmission also includes step S7: EMS monitors the transmission oil temperature: If the oil temperature does not exceed the first oil temperature overheating threshold, the temperature control module will eventually output the required opening degree of the first temperature control module, and the cooling fan will eventually output the required speed of the first cooling fan.

Images