A control method for engine torque limitation in failure mode of automatic transmission

Abstract

The application discloses a control method for engine torque limitation under a failure mode of an automatic transmission, and belongs to the technical field of the transmission. The method is as follows: the gearbox enters a failure state; a gearbox control unit carries out corresponding torque limitation control according to different failure states; after the gearbox completes the torque limitation control under different failure states, it is judged whether the current real-time torque under the failure state is less than a maximum torque threshold value marked in the gearbox control unit; if yes, the torque limitation control is exited; otherwise, the torque limitation control is continuously carried out until the current real-time torque under the failure state is less than the maximum torque threshold value marked in the gearbox control unit; and the failure mode is exited after a power-off and power-on operation of a vehicle customer is completed. The application limits the engine torque according to different gearbox failure modes, protects the gearbox to the maximum extent, prevents other components from being damaged, causes secondary damage of the gearbox, and increases the vehicle maintenance cost of the user.

Description

Technical Field

[0001] This invention relates to a control method for engine torque limiting under automatic transmission fault modes, belonging to the field of transmission technology. Background Technology

[0002] In existing technologies, when a transmission enters a fault mode, it mostly employs a basic power-off mechanical limp-off mode. While this mode can temporarily maintain the vehicle's basic driving capability, it lacks effective control over engine torque, which may cause the transmission to continue to bear excessive torque loads even in a faulty state. This not only increases the risk of damage to other transmission components but may also trigger more serious secondary damage, thus significantly increasing the overall vehicle repair costs for car owners. Summary of the Invention

[0003] To address the problems existing in the background art, the present invention provides a control method for engine torque limitation under automatic transmission fault modes.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for controlling engine torque limitation under automatic transmission fault mode, the method comprising the following steps:

[0005] S1: When a vehicle experiences a transmission failure, the transmission enters a fault state;

[0006] S2: The transmission control unit performs corresponding torque limiting control based on different fault conditions;

[0007] The fault states include clutch speed ratio fault state, transmission holding in a single gear fault state, and transmission shifting into neutral fault state.

[0008] S3: After completing torque limiting control under different fault conditions, the transmission determines whether the current real-time torque under the fault condition is less than the maximum torque threshold calibrated in the transmission control unit. If it is less, the transmission exits the torque limiting control; otherwise, the transmission continues to perform torque limiting control until the current real-time torque under the fault condition is less than the maximum torque threshold calibrated in the transmission control unit.

[0009] S4: The fault mode will exit after the customer completes a power-off and power-on operation.

[0010] The control method for torque limiting control corresponding to the clutch speed ratio fault state includes the following steps:

[0011] S201: Speed ​​ratio fault detected, transmission enters fault state;

[0012] S202: Finding a safe driving gear: While preparing to shift gears, the transmission control unit performs normal torque reduction control; and at the same time performs torque limiting control to keep the transmission input torque at 0N, so that the engine output torque is equal to the total friction torque;

[0013] Finding a safe driving gear includes the following steps:

[0014] S20201: The transmission control unit analyzes the current vehicle driving status;

[0015] S20202: Based on the analysis results, select gears that meet the requirements for safe driving from the available gears in the transmission;

[0016] S20203: Identify at least one suitable gear as an alternative and prepare to perform a gear shifting operation.

[0017] S203: Perform a gear shifting operation;

[0018] S204: After entering a safe gear, the transmission control unit continues to monitor the transmission ratio status and the vehicle's driving status.

[0019] The control method for torque limiting control corresponding to a single-gear fault state of the transmission includes the following steps:

[0020] S201: Single gear fault detected, transmission enters fault state;

[0021] S202: The vehicle must be driven in a single gear;

[0022] S203: Limits engine output torque to maintain transmission input torque and prevents it from exceeding the maximum torque threshold calibrated in the transmission control unit; if the transmission input torque exceeds the maximum torque threshold calibrated in the transmission control unit, the transmission control unit performs conventional torque reduction control to ensure that the transmission input torque only reaches the calibrated limit value.

[0023] The control method for torque limiting control corresponding to the transmission entering neutral fault state includes the following steps:

[0024] S201: Neutral gear fault detected, transmission enters fault state;

[0025] S202: The transmission remains in neutral (N) mode;

[0026] S203: Press the accelerator pedal;

[0027] S204: Detects and determines the value of the transmission input torque. If the transmission input torque exceeds the maximum torque threshold calibrated in the transmission control unit, the transmission control unit performs conventional torque reduction control to ensure that the transmission input torque can only reach the calibrated limit value.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] This invention limits engine torque for different transmission failure modes, maximizing transmission protection and preventing damage to other components, which could lead to secondary transmission damage and increase overall vehicle maintenance costs for users. Attached Figure Description

[0030] Figure 1 This is a flowchart of the torque limiting process under clutch speed ratio failure conditions according to the present invention;

[0031] Figure 2 This is a flowchart of the torque limiting process under the fault state of the transmission maintaining a single gear in the present invention;

[0032] Figure 3 This is a flowchart illustrating the torque limitation process when the transmission enters neutral due to a fault. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] A method for controlling engine torque limitation under automatic transmission fault modes, the method comprising the following steps:

[0035] S1: When the vehicle is in normal driving condition and a sudden transmission failure occurs, the transmission enters a fault state.

[0036] S2: The transmission control unit performs corresponding torque limiting control based on different fault conditions;

[0037] S3: After completing torque limiting control under different fault conditions, the transmission determines whether the current real-time torque under the fault condition is less than the maximum torque threshold calibrated in the transmission control unit. If it is less, the transmission exits the torque limiting control; otherwise, the transmission continues to perform torque limiting control until the current real-time torque under the fault condition is less than the maximum torque threshold calibrated in the transmission control unit.

[0038] S4: The fault mode will exit after the customer completes a power-off and power-on operation.

[0039] The fault states described in S2 include clutch speed ratio fault state, transmission holding single gear fault state, and transmission entering neutral fault state.

[0040] The control method for torque limiting control corresponding to the clutch speed ratio fault state includes the following steps:

[0041] S201: Speed ​​ratio fault detected, transmission enters fault state;

[0042] S20101: During the operation of the automatic transmission, the transmission control unit monitors the speed ratio status of the transmission in real time.

[0043] S20102: When the transmission control unit detects an abnormal gear ratio, it immediately determines that it is a gear ratio fault, the transmission enters a fault state, and the corresponding fault handling process is triggered.

[0044] S202: Finding a Safe Gear: While preparing to shift gears, the transmission control unit executes routine torque reduction control to decrease the transmission input torque. This routine torque reduction control includes adjusting the engine throttle opening and changing the fuel injection quantity. Simultaneously, torque limiting control is added to further limit the engine output torque. Torque limiting control includes adjusting the engine torque output curve and cutting off part of the fuel supply. This maintains the transmission input torque at 0N, ensuring that the engine output torque equals the total friction torque.

[0045] Finding a safe driving gear includes the following steps:

[0046] S20201: After confirming a gear ratio fault, the transmission control unit analyzes the current vehicle driving status (such as speed, acceleration, road conditions, etc.);

[0047] S20202: Based on the analysis results, select gears that meet the requirements for safe driving from the available gears in the transmission;

[0048] S20203: Identify at least one suitable gear as an alternative and prepare to perform a gear shifting operation.

[0049] S203: Perform a gear shifting operation;

[0050] S204: After entering a safe gear, the transmission control unit continues to monitor the transmission ratio status and vehicle driving status, ensuring good and safe gear selection.

[0051] When an automatic transmission experiences a gear ratio failure, the transmission control unit's normal logic dictates that it must sequentially shift gears under the current fault condition to find a usable and suitable safe driving gear. During this shifting process, clutch slippage can cause the turbocharger and engine speeds to fail to decrease in time, resulting in runaway transmission. Continuing to apply torque during this situation will exacerbate clutch damage.

[0052] In addition to conventional torque reduction control, this invention adds torque limiting control during the process of finding a safe gear position. This limits the engine output torque, keeping the transmission input torque at 0N to complete the shift. Only the total torque, which is approximately equal to the friction torque, is allowed to be output by the engine, thus ensuring the safe completion of the shift.

[0053] The control method for torque limiting control corresponding to a single-gear fault state of the transmission includes the following steps:

[0054] S201: Single gear fault detected, transmission enters fault state;

[0055] S20101: The transmission control unit monitors the operating status of the automatic transmission in real time.

[0056] S20102: When the transmission control unit detects serious damage to the transmission or a communication failure that prevents the transmission control unit from changing gears, the fault handling process is immediately triggered.

[0057] S202: The vehicle shall be driven in a single gear (such as D gear).

[0058] S203: Limits engine output torque to maintain transmission input torque and prevents it from exceeding the maximum torque threshold calibrated in the transmission control unit; if the transmission input torque exceeds the maximum torque threshold calibrated in the transmission control unit, the transmission control unit performs conventional torque reduction control to ensure that the transmission input torque only reaches the calibrated limit value.

[0059] When an automatic transmission suffers severe damage or experiences communication failures with components such as the engine, the transmission control unit may lack critical shift signals, causing it to attempt to change gears again. When this results in the transmission maintaining a single, fixed gear, it's equivalent to the automatic transmission moving at a fixed gear ratio. This invention limits the engine output torque in this type of fault, ensuring the transmission input torque fluctuates within a fixed range, not exceeding a certain maximum value. This value is the engine friction torque plus a fixed amount. This prevents the vehicle speed from continuously increasing due to rising torque, which could cause the engine speed to exceed the limit at the fixed gear ratio, resulting in damage to the engine or other hardware.

[0060] In D mode, when the accelerator is pressed, the engine torque begins to rise. Once it exceeds the value calibrated in the transmission control unit, the output will be limited, so that the transmission input torque can only reach the calibrated limit. When the accelerator is released, the engine torque begins to drop. After dropping to slightly less than the value calibrated in the transmission control unit (to prevent torque fluctuations from causing continuous torque limiting and exiting torque limiting), the torque limiting will exit.

[0061] The control method for torque limiting control corresponding to the transmission entering neutral fault state includes the following steps:

[0062] S201: Neutral gear fault detected, transmission enters fault state;

[0063] S202: The transmission remains in neutral (N) mode;

[0064] S203: Press the accelerator pedal;

[0065] S204: Detects and determines the value of the transmission input torque. If the transmission input torque exceeds the maximum torque threshold calibrated in the transmission control unit, the transmission control unit performs conventional torque reduction control to ensure that the transmission input torque can only reach the calibrated limit value.

[0066] When an automatic transmission suffers severe damage, such as an open circuit, short circuit to power, or short circuit to ground, or when it becomes unable to move due to issues like power supply or gear mismatch, this invention will also limit the engine torque in such a state where the vehicle cannot move in neutral. This keeps the transmission input torque at a certain positive value, which should not be too high, ensuring that the engine speed rises slowly when the accelerator is pressed. This prevents the engine from idling and causing a rapid increase in speed.

[0067] When this fault condition is entered, the transmission remains in neutral (N). When the accelerator is pressed, the engine torque begins to rise. Once it exceeds the value calibrated in the transmission control unit, the output will be limited, so that the transmission input torque can only reach the calibrated limit. When the accelerator is released, the engine torque begins to drop. After dropping to slightly less than the value calibrated in the transmission control unit (to prevent torque fluctuations from causing continuous torque limiting and exiting torque limiting), the torque limiting will exit.

[0068] When the transmission enters a fault mode, the probability of secondary damage to the transmission due to imperfect strategies is significantly reduced. At the same time, the invention can also enable the transmission to perform as many normal shift operations as possible when it enters a fault state, increasing the driving options and driving experience for vehicle users.

[0069] 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, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0070] 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 controlling engine torque limiting under automatic transmission fault modes, characterized in that: The method includes the following steps: S1: When a vehicle experiences a transmission failure, the transmission enters a fault state; S2: The transmission control unit performs corresponding torque limiting control based on different fault conditions; The fault states include clutch ratio fault state, transmission holding single gear fault state, and transmission entering neutral fault state. The control method for torque limiting control corresponding to the clutch speed ratio fault state includes the following steps: S201: Speed ​​ratio fault detected, transmission enters fault state; S202: Finding a safe driving gear: While preparing to shift gears, the transmission control unit performs normal torque reduction control; At the same time, torque limiting control is added to keep the transmission input torque at 0N, so that the engine output torque is equal to the total friction torque; S203: Perform a gear shifting operation; S204: After entering a safe gear, the transmission control unit continues to monitor the transmission ratio status and vehicle driving status; S3: After completing torque limiting control under different fault conditions, the transmission determines whether the current real-time torque under the fault condition is less than the maximum torque threshold calibrated in the transmission control unit. If it is less, the transmission exits the torque limiting control; otherwise, the transmission continues to perform torque limiting control until the current real-time torque under the fault condition is less than the maximum torque threshold calibrated in the transmission control unit. S4: The fault mode will exit after the customer completes a power-off and power-on operation.

2. The control method for engine torque limiting under automatic transmission fault mode according to claim 1, characterized in that: S202 describes the process of finding a safe driving gear, which includes the following steps: S20201: The transmission control unit analyzes the current vehicle driving status; S20202: Based on the analysis results, select gears that meet the requirements for safe driving from the available gears in the transmission; S20203: Identify at least one suitable gear as an alternative and prepare to perform a gear shifting operation.

3. The control method for engine torque limiting under automatic transmission fault mode according to claim 2, characterized in that: The control method for torque limiting control corresponding to a single-gear fault state of the transmission includes the following steps: S201: Single gear fault detected, transmission enters fault state; S202: The vehicle shall maintain a single gear while driving; S203: Limits engine output torque to maintain transmission input torque and prevents it from exceeding the maximum torque threshold calibrated in the transmission control unit; if the transmission input torque exceeds the maximum torque threshold calibrated in the transmission control unit, the transmission control unit performs conventional torque reduction control to ensure that the transmission input torque only reaches the calibrated limit value.

4. The control method for engine torque limiting under automatic transmission fault mode according to claim 2, characterized in that: The control method for torque limiting control corresponding to the transmission entering neutral fault state includes the following steps: S201: Neutral gear fault detected, transmission enters fault state; S202: The transmission remains in neutral (N) mode; S203: Press the accelerator pedal; S204: Detects and determines the value of the transmission input torque. If the transmission input torque exceeds the maximum torque threshold calibrated in the transmission control unit, the transmission control unit performs conventional torque reduction control to ensure that the transmission input torque can only reach the calibrated limit value.

Images