Low-temperature protection method for automatic transmission under extremely cold working condition

Abstract

The invention discloses an automatic transmission extremely cold working condition low-temperature protection method and belongs to the technical field of automatic transmissions. The method comprises the steps that gear locking and idling warming-up control under the extremely cold temperature are executed; executing the lowest gear limit control of the low-temperature interval; low-temperature torque limiting strategy control is executed, and the input torque in the gear shifting process is dynamically limited; and the transmission life cycle temperature working condition is recorded. Dry friction and impact load under high viscosity of cold oil in the extremely cold starting stage are avoided, the impact and ablation risk of low-gear large torque on a transmission system and a friction plate during low-temperature driving is reduced, thermal load and abrasion of the friction plate under the low-temperature high-viscosity working condition are reduced, and the overall service life of a friction element and a transmission is prolonged.

Description

Technical Field

[0001] This invention relates to a low-temperature protection method for automatic transmissions under extremely cold operating conditions, belonging to the field of automatic transmission technology. Background Technology

[0002] When automatic transmissions operate in extremely cold regions, the performance of the lubricating oil deteriorates significantly under these conditions. The oil viscosity increases dramatically, and its fluidity decreases, preventing the timely formation of an effective oil film on the surfaces of moving parts such as gears and bearings. This leads to insufficient lubrication and accelerated wear. Furthermore, the different shrinkage rates of metal components at low temperatures can cause abnormal changes in the clearances between parts, making them prone to impacts and jamming during operation. Low temperatures can also cause seals to harden and fail, further damaging the transmission. Extremely cold environments may also exceed the minimum operating temperature limit of the TCU (Transmission Control Unit), affecting the stability of the control logic.

[0003] In the existing technology, there is a lack of systematic low-temperature protection solutions for automatic transmissions in extremely cold conditions. These solutions cannot effectively address issues such as insufficient lubrication, component impact, seal failure, and abnormal TCU operation in extremely cold environments. As a result, the transmission is at high risk of hardware damage when used in extremely cold regions, and its reliability and safety are difficult to guarantee. Summary of the Invention

[0004] To address the problems existing in the background technology, the present invention provides a method for low-temperature protection of automatic transmissions under extremely cold operating conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a low-temperature protection method for automatic transmissions under extremely cold operating conditions, wherein the method is implemented by the TCU based on the oil temperature T collected by the transmission oil temperature sensor. oil Performing logical judgments and executing control measures includes the following steps:

[0006] S1: Perform gear lock-up and idle warm-up control under extremely cold temperatures;

[0007] S2: Executes the lowest gear limit control in the low temperature range;

[0008] S3: Implement low-temperature torque limiting strategy control to dynamically limit the input torque during gear shifting;

[0009] S4: Records the temperature conditions throughout the transmission's lifecycle.

[0010] Furthermore, step S1 includes the following steps:

[0011] S101: Preset first extreme cold temperature threshold T1, TCU collects the oil temperature T from the transmission oil temperature sensor in real time. oil ;

[0012] S102: When the TCU detects T oil When the temperature is <T1, the system enters the extreme cold protection mode, which restricts the shift lever from P to drive.

[0013] S103: At the same time, the TCU sends a prompt message to the instrument cluster via the CAN bus, displays a text prompt on the instrument cluster or central control display interface, and lights up the corresponding prompt icon to provide feedback to the driver on the current protection status;

[0014] S104: The engine is kept idling in place, and the transmission fluid is heated through heat conduction to achieve vehicle warm-up in place;

[0015] S105: When the TCU detects oil temperature T oil Increase to release condition T oil When the value is greater than T1+ΔT, the TCU releases the gear restriction, allowing the driver to perform normal gear shifting operations. ΔT represents the temperature difference released.

[0016] Furthermore, the control strategy described in S102, which includes restricting the shift lever from P gear to drive gear, is any one of the following:

[0017] Strategy 1: When shifting out of P gear, the TCU only allows the shift lever to switch to N gear and prohibits it from engaging drive gears;

[0018] Strategy 2: The TCU directly prevents the gear shift lever from shifting out of P gear, maintaining the P gear locked state.

[0019] Furthermore, step S2 includes the following steps:

[0020] S201: Preset the second low-temperature calibration threshold T2, and the TCU collects the oil temperature T from the transmission oil temperature sensor in real time. oil ;

[0021] S202: When the TCU detects T1≤T oil When the temperature is <T2, the system determines that the vehicle is in the low-temperature operating range;

[0022] S203: If the driver selects D gear, the transmission will be controlled according to the current D gear shifting logic, and the lowest gear limiting logic will be activated at the same time.

[0023] Furthermore, the minimum gear limiting logic described in S203 includes:

[0024] S20301: During the calculation of the target gear for gear shifting, gear 1 is set as an unavailable gear, and gear 1 is disabled from participating in gear shifting;

[0025] S20302: When starting the vehicle, start directly in 2nd gear. If the TCU detects difficulty in starting through the vehicle speed sensor and torque sensor, it will perform power compensation, but it is still prohibited to switch to 1st gear.

[0026] S20303: As the vehicle speed increases, the transmission normally shifts into a higher gear, and the shift logic remains consistent with the original shift diagram.

[0027] Furthermore, step S3 includes the following steps:

[0028] S301: When a shift request is detected, the TCU determines the current oil temperature based on the T value. oil The maximum allowable input torque T is calculated based on a preset calibration chart, considering the current gear, target gear, and shift phase. max ;

[0029] S302: The TCU sends a torque request limit T to the engine ECU via the CAN bus. req And T req ≤T max ;

[0030] S303: If the transmission input torque exceeds the maximum torque threshold calibrated in the TCU, the TCU will perform conventional torque reduction control to force the transmission input torque to be limited within the calibrated limit.

[0031] S304: Optimizes the response rate of the torque limit curve to ensure smooth shifting and driving safety while reducing the thermal load and wear of friction plates under low temperature and high viscosity conditions.

[0032] Furthermore, step S4 includes the following steps:

[0033] S401: Multiple temperature ranges are pre-divided within the TCU, and each range corresponds to an accumulation time register;

[0034] S402: The TCU reads the current oil temperature T at a fixed sampling period. oil Based on its temperature range, the timing register of the corresponding range is accumulated for timing.

[0035] S403: During maintenance or diagnosis, the service tool can be connected through the diagnostic interface to read the cumulative operating time of each temperature range, thus obtaining the total operating time of the transmission in different temperature ranges.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] This invention addresses several issues in automatic transmissions under extreme cold conditions through a comprehensive design that includes gear lock-up and idle warm-up control at extremely cold temperatures, minimum gear limitation in low-temperature ranges, low-temperature shift torque limiting strategies, and full-lifecycle temperature condition recording. These issues include insufficient lubrication due to degraded lubricating oil performance, abnormal clearances and impact jamming caused by metal component shrinkage, seal failure, and compromised TCU operational stability. It effectively avoids dry friction and impact loads under high-viscosity cold oil during the start-up phase in extremely cold environments, reduces the risk of impact and ablation on the transmission system and friction plates during low-temperature driving with high torque at low gears, reduces the thermal load and wear on friction plates under low-temperature, high-viscosity conditions, and extends the service life of friction components and the overall transmission. Furthermore, it enables quantifiable assessment of cumulative damage under extremely cold conditions, providing support for subsequent calibration optimization, reliability design, and fault analysis. All strategies can be adjusted through calibration, ensuring transmission safety and reliability without significantly affecting vehicle drivability, demonstrating excellent engineering feasibility and application potential. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] A method for low-temperature protection of an automatic transmission under extremely cold conditions, wherein the method is performed by the TCU based on the oil temperature T collected by the transmission oil temperature sensor. oil Performing logical judgments and executing control measures includes the following steps:

[0040] S1: Perform gear lock-up and idle warm-up control under extremely cold temperatures;

[0041] S2: Executes the lowest gear limit control in the low temperature range;

[0042] S3: When the TCU detects T oil When the temperature is <T2, the low-temperature torque limiting flag is set. By working in conjunction with the ECU (engine control unit) or electric drive control unit (for hybrid or pure electric drive vehicles), the low-temperature torque limiting strategy control is executed to dynamically limit the input torque during the shifting process.

[0043] S4: Records the temperature conditions throughout the transmission's lifecycle.

[0044] Furthermore, step S1 includes the following steps:

[0045] S101: Preset first extreme cold temperature threshold T1 (e.g., -40℃, calibrated according to vehicle model and actual usage environment), TCU collects the transmission oil temperature T from the transmission oil temperature sensor in real time.oil ;

[0046] S102: When the TCU detects T oil When the temperature is <T1, the system enters the extreme cold protection mode, which restricts the shift lever from P to drive (D, R).

[0047] S103: At the same time, the TCU sends a prompt message to the instrument cluster via the CAN bus, displays a text prompt on the instrument cluster or central control display interface that the transmission is under low temperature protection and that the engine should be warmed up in place, and lights up the corresponding prompt icon to provide feedback to the driver on the current protection status.

[0048] S104: The engine is kept idling in place, and the transmission fluid is heated through heat conduction to achieve vehicle warm-up in place;

[0049] S105: When the TCU detects oil temperature T oil Increase to release condition T oil When the value is greater than T1+ΔT, the TCU releases the gear restriction, allowing the driver to perform normal gear shifting operations. ΔT represents the temperature difference released and can be calibrated.

[0050] Furthermore, the control strategy described in S102, which includes restricting the shift lever from P gear to drive gear, is any one of the following:

[0051] Strategy 1: When the driver attempts to shift out of P gear, the TCU only allows the shift lever to switch to N gear and prohibits the shifting into D gear, R gear, and other drive gears. The TCU will also display a low-temperature protection message on the instrument panel or central control screen, asking the driver to warm up the transmission while it is stationary.

[0052] Strategy 2: The TCU directly prevents the gear shift lever from shifting out of P gear, maintaining the P gear locked state.

[0053] Furthermore, step S2 includes the following steps:

[0054] S201: Preset second low-temperature calibration threshold T2 (e.g., -30℃, which can be calibrated according to vehicle model and actual usage environment). The TCU collects the transmission oil temperature T from the transmission oil temperature sensor in real time. oil ;

[0055] S202: When the TCU detects T1≤T oil When the temperature is <T2, the system determines that the vehicle is in the low-temperature operating range;

[0056] S203: If the driver selects D gear, the transmission will be controlled according to the current D gear shifting logic (based on signals such as throttle opening and vehicle speed), and the lowest gear limiting logic will be activated at the same time.

[0057] Furthermore, the minimum gear limiting logic described in S203 includes:

[0058] S20301: During the calculation of the target gear for shifting, gear 1 is set as an unavailable gear. The shifting logic is based on the original shifting diagram and signals such as throttle opening and vehicle speed, but gear 1 is shielded from participating in shifting. This reduces the impact on the transmission mechanism and friction plates by avoiding the use of the large transmission ratio of gear 1 in extremely cold temperatures.

[0059] S20302: When starting the vehicle, start directly in 2nd gear. If the TCU detects difficulty in starting through the vehicle speed sensor and torque sensor, it will compensate for the power by moderately increasing the engine idle speed (the increase shall not exceed 300 rpm, which can be calibrated) or allowing short-term slippage, but it is still prohibited to shift into 1st gear.

[0060] S20303: As the vehicle speed increases, the transmission normally shifts into higher gears such as 3rd and 4th gear, and the shift logic remains consistent with the original shift diagram.

[0061] Furthermore, step S3 includes the following steps:

[0062] S301: When a shift request (such as 2→3, 3→4, etc.) is detected, the TCU adjusts the current oil temperature T. oil The maximum allowable input torque T is calculated based on a preset calibration chart, considering the current gear, target gear, and shifting phase (torque reduction phase, torque engagement phase, etc.). max The calibration chart is predetermined through bench testing and covers torque limiting parameters under different low-temperature operating conditions.

[0063] S302: The TCU sends a torque request limit T to the engine ECU via the CAN bus. req And T req ≤T max ;

[0064] S303: If the transmission input torque exceeds the maximum torque threshold calibrated in the TCU, the TCU will perform conventional torque reduction control to forcibly limit the transmission input torque within the calibrated limit, preventing the actual torque during the shifting process from exceeding the limit.

[0065] S304: Optimizes the response rate of the torque limit curve (response time not exceeding 100ms, calibrable) to ensure smooth shifting and driving safety while reducing the thermal load and wear of friction plates under low temperature and high viscosity conditions.

[0066] Through the aforementioned low-temperature torque limiting control, the thermal shock and wear of the friction plates during gear shifting are effectively reduced while ensuring vehicle power performance.

[0067] Furthermore, step S4 includes the following steps:

[0068] S401: Multiple temperature ranges are pre-defined within the TCU, each corresponding to a cumulative time register. For extremely cold operating conditions, the low-temperature ranges are meticulously divided. Typical temperature range divisions are as follows:

[0069] Interval 1: T oil <-40℃;

[0070] Interval 2: -40℃≤T oil < -30℃;

[0071] Interval 3: -30℃≤T oil <-20℃;

[0072] Interval 4: -20℃≤T oil <0℃;

[0073] Interval 5: 0℃≤T oil <20℃;

[0074] Interval 6: T oil ≥20℃;

[0075] In extremely cold overseas environments or specific markets, temperature range division and recording resolution can be adjusted through calibration.

[0076] S402: The TCU reads the current oil temperature T at a fixed sampling period (calibrable, typical value is 1s or 10s). oil Based on its temperature range, the timing register of the corresponding range is accumulated (the corresponding duration is added for each sampling period); the timing register is stored in non-volatile memory to prevent the accumulated data from being lost after the vehicle is powered off;

[0077] S403: During maintenance or diagnosis, the service tool is connected through the diagnostic interface to read the cumulative operating time in each temperature range. This provides the total operating time of the transmission in different temperature ranges, providing data for transmission reliability analysis, warranty determination, and subsequent calibration optimization. It is also used to analyze the frequency of vehicle use in extremely cold regions, verify the rationality of calibration strategies, and provide design input for subsequent iterative products.

[0078] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the present invention.

[0079] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for low-temperature protection of an automatic transmission under extremely cold operating conditions, characterized in that: The method is based on the oil temperature T collected by the transmission oil temperature sensor by the TCU. oil Performing logical judgments and executing control measures includes the following steps: S1: Perform gear lock-up and idle warm-up control under extremely cold temperatures; S2: Executes the lowest gear limit control in the low temperature range; S3: Implement low-temperature torque limiting strategy control to dynamically limit the input torque during gear shifting; S4: Records the temperature conditions throughout the transmission's lifecycle.

2. The method for low-temperature protection of an automatic transmission under extremely cold conditions according to claim 1, characterized in that: S1 includes the following steps: S101: Preset first extreme cold temperature threshold T1, TCU collects the oil temperature T from the transmission oil temperature sensor in real time. oil ; S102: When the TCU detects T oil When the temperature is <T1, the system enters the extreme cold protection mode, which restricts the shift lever from P to drive. S103: At the same time, the TCU sends a prompt message to the instrument cluster via the CAN bus, displays a text prompt on the instrument cluster or central control display interface, and lights up the corresponding prompt icon to provide feedback to the driver on the current protection status; S104: The engine is kept idling in place, and the transmission fluid is heated through heat conduction to achieve vehicle warm-up in place; S105: When the TCU detects oil temperature T oil Increase to release condition T oil When the value is greater than T1+ΔT, the TCU releases the gear restriction, allowing the driver to perform normal gear shifting operations. ΔT represents the temperature difference released.

3. The method for low-temperature protection of an automatic transmission under extremely cold operating conditions according to claim 2, characterized in that: S102 includes a control strategy that restricts the shift lever from P gear to drive gear, which is any of the following: Strategy 1: When shifting out of P gear, the TCU only allows the shift lever to switch to N gear and prohibits it from engaging drive gears; Strategy 2: The TCU directly prevents the gear shift lever from shifting out of P gear, maintaining the P gear locked state.

4. The method for low-temperature protection of an automatic transmission under extremely cold conditions according to claim 3, characterized in that: S2 includes the following steps: S201: Preset the second low-temperature calibration threshold T2, and the TCU collects the oil temperature T from the transmission oil temperature sensor in real time. oil ; S202: When the TCU detects T1≤T oil When the temperature is <T2, the system determines that the vehicle is in the low-temperature operating range; S203: If the driver selects D gear, the transmission will be controlled according to the current D gear shifting logic, and the lowest gear limiting logic will be activated at the same time.

5. The method for low-temperature protection of an automatic transmission under extremely cold conditions according to claim 4, characterized in that: The minimum gear limiting logic described in S203 includes: S20301: During the calculation of the target gear for gear shifting, gear 1 is set as an unavailable gear, and gear 1 is disabled from participating in gear shifting; S20302: When starting the vehicle, start directly in 2nd gear. If the TCU detects difficulty in starting through the vehicle speed sensor and torque sensor, it will perform power compensation, but it is still prohibited to switch to 1st gear. S20303: As the vehicle speed increases, the transmission normally shifts into a higher gear, and the shift logic remains consistent with the original shift diagram.

6. The method for low-temperature protection of an automatic transmission under extremely cold operating conditions according to claim 5, characterized in that: S3 includes the following steps: S301: When a shift request is detected, the TCU determines the current oil temperature based on the T value. oil The maximum allowable input torque T is calculated based on a preset calibration chart, considering the current gear, target gear, and shift phase. max ; S302: The TCU sends a torque request limit T to the engine ECU via the CAN bus. req And T req ≤T max ; S303: If the transmission input torque exceeds the maximum torque threshold calibrated in the TCU, the TCU will perform conventional torque reduction control to force the transmission input torque to be limited within the calibrated limit. S304: Optimizes the response rate of the torque limit curve to ensure smooth shifting and driving safety while reducing the thermal load and wear of friction plates under low temperature and high viscosity conditions.

7. The method for low-temperature protection of an automatic transmission under extremely cold operating conditions according to claim 1, characterized in that: S4 includes the following steps: S401: Multiple temperature ranges are pre-divided within the TCU, and each range corresponds to an accumulation time register; S402: The TCU reads the current oil temperature T at a fixed sampling period. oil Based on its temperature range, the timing register of the corresponding range is accumulated for timing. S403: During maintenance or diagnosis, the service tool can be connected through the diagnostic interface to read the cumulative operating time of each temperature range, thus obtaining the total operating time of the transmission in different temperature ranges.