Skid detection and gear control method for vehicle carrying automatic transmission

Abstract

The invention discloses a slip detection and gear control method for a vehicle carrying an automatic transmission, and belongs to the technical field of vehicle transmission system control. The method comprises the following steps that the signal input module receives an input signal through a whole vehicle CAN communication network, calls the rotating speed of an output shaft of a transmission and torque increasing parameters of a hydraulic torque converter of the transmission and then preprocesses the input signal; the road condition diagnosis module judges whether the vehicle slips or not, and if the vehicle slips, the TCU enters the gear processing module to fix the current gear; when the gear is continuously fixed for preset time and the slipping condition is not met any more, the gear limiting mode is quitted; or during the gear fixing period, when the driver switches the M gear or other modes, the gear limiting mode is quitted. According to the invention, the accuracy of slip state detection under complex terrains is improved; when slipping is detected and the vehicle speed is lower than the calibration threshold value, the TCU fixes the current gear immediately, gear switching under the abnormal working condition is effectively restrained, the clutch overload risk and gear impact are reduced, and the service life of mechanical parts of the transmission is prolonged.

Description

Technical Field

[0001] The present invention relates to a method for detecting slippage and controlling gear positions of a vehicle equipped with an automatic transmission, and belongs to the technical field of vehicle transmission system control. Background Art

[0002] Off-road driving often involves encountering complex road conditions, such as desert, snow, and mud. These unique terrains can easily cause wheel slip. Furthermore, drivers may actively engage four-wheel drive mode or disable stability systems (such as ESP) to improve vehicle maneuverability, causing the torque and speed of the automatic transmission to fluctuate dramatically.

[0003] Existing automatic transmissions lack precise detection of slippage and dynamic gear adjustment mechanisms for these conditions. When the transmission output shaft speed experiences an abnormal, sudden change due to slippage, traditional control strategies are unable to promptly limit gear shifts or adjust the torque transfer path. This can lead to clutch overload, increased gear impact, and other issues. Long-term operation can accelerate wear of the transmission's mechanical components and even cause failure. Summary of the Invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a vehicle slip detection and gear control method equipped with an automatic transmission.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for detecting slippage and controlling the gear position of a vehicle equipped with an automatic transmission, the method comprising the following steps:

[0006] S1: The signal input module receives the input signal through the vehicle CAN communication network and calls the transmission output shaft speed and transmission torque converter torque increase parameters for pre-processing;

[0007] S2: The road condition diagnosis module determines whether the vehicle is skidding. If it is determined that the vehicle is skidding, it proceeds to S3;

[0008] S3: TCU enters the gear processing module to fix the current gear;

[0009] S4: When the gear is held in a fixed position for a preset time until the slipping condition is no longer met, the limited gear mode is exited; or when the driver switches to M gear or other modes during the gear holding period, the limited gear mode is exited.

[0010] Furthermore, the input signal in S1 includes the longitudinal acceleration, wheel speed, throttle, gear lever position and engine input torque signal of the vehicle.

[0011] Furthermore, the determination condition of whether the vehicle is slipping in S2 is that at least one of the following slip conditions is met and the vehicle speed is lower than a calibrated low speed threshold, wherein the slip conditions are:

[0012] Condition 1: The transmission output shaft speed change rate exceeds the calibration threshold;

[0013] Condition 2: The generalized ramp torque exceeds the preset upper and lower limits;

[0014] Condition three: The transmission output shaft speed exceeds the calibrated value and the longitudinal acceleration change of the vehicle is less than the calibrated range.

[0015] Furthermore, the transmission output shaft speed change rate of condition 1 is The calculation formula is as follows:

[0016] (1)

[0017] In formula (1):

[0018] for The transmission output shaft speed at time t;

[0019] for The transmission output shaft speed at time .

[0020] Furthermore, the calculation process of the generalized ramp torque described in condition 2 is as follows:

[0021] S201: The engine input torque signal is processed by the torque converter torque multiplication module to obtain the transmission input shaft torque;

[0022] S202: Calculate traction torque :

[0023] (2)

[0024] In formula (2):

[0025] is the transmission input shaft torque;

[0026] is the gear ratio;

[0027] is the main reducer speed ratio;

[0028] is gear efficiency;

[0029] S203: Calculate generalized ramp torque :

[0030] (3)

[0031] In formula (3):

[0032] for road resistance;

[0033] is wind resistance;

[0034] is the acceleration resistance;

[0035] is the wheel rolling radius.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention constructs multi-dimensional slip judgment conditions based on the correlation analysis of the output shaft speed change rate, generalized ramp torque, and longitudinal acceleration and speed, which significantly improves the accuracy of slip state detection under complex terrain; when slip is detected and the vehicle speed is lower than the calibration threshold, the TCU immediately fixes the current gear, effectively suppresses gear switching under abnormal working conditions, reduces the risk of clutch overload and gear impact, and extends the service life of the transmission mechanical components; at the same time, adaptive exit from the limited gear mode is achieved through preset time thresholds or the driver's active switching to M gear and other modes, taking into account the needs of slip protection and driving flexibility; finally, through a closed-loop control strategy from signal acquisition, working condition diagnosis to gear intervention, an optimization mechanism is formed for the drastic fluctuation characteristics of torque and speed in off-road scenarios, which significantly improves the reliability and durability of the automatic transmission under special working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a flow chart of the present invention;

[0039] Figure 2 It is a flow chart of the road condition diagnosis module and the gear processing module. DETAILED DESCRIPTION

[0040] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] A method for detecting slippage and controlling gear position of a vehicle equipped with an automatic transmission, the method comprising the following steps:

[0042] S1: The signal input module receives the input signal through the vehicle CAN communication network and calls the transmission output shaft speed and transmission torque converter torque increase parameters for pre-processing;

[0043] S2: The road condition diagnosis module determines whether the vehicle is skidding. If it is determined that the vehicle is skidding, it proceeds to S3;

[0044] S3: The TCU (automatic transmission controller) enters the gear processing module to fix the current gear and no longer shifts gears to protect the transmission.

[0045] S4: When the gear is held in a fixed position for a preset time until the slipping condition is no longer met, the limited gear mode is exited; or when the driver switches to M gear or other modes during the gear holding period, the limited gear mode is exited.

[0046] M gear or other modes can be selected through TCU according to needs.

[0047] Other modes include but are not limited to sports, snow, four-wheel drive and other vehicle modes.

[0048] Furthermore, the input signal in S1 includes the longitudinal acceleration, wheel speed, throttle, gear lever position and engine input torque signal of the vehicle.

[0049] Furthermore, the determination condition of whether the vehicle is slipping in S2 is that at least one of the following slip conditions is met and the vehicle speed is lower than a calibrated low speed threshold, wherein the slip conditions are:

[0050] Condition 1: The transmission output shaft speed change rate exceeds the calibration threshold rapidly within a short period of time (0.5-2s);

[0051] Condition 2: The generalized ramp torque exceeds the preset upper and lower limits;

[0052] Under normal circumstances, the vehicle's generalized ramp torque fluctuates around 0. When driving uphill or downhill, the generalized ramp torque varies within a wider range (positive limit: +2000 to +4500 N·m; negative limit: -1000 to -3000 N·m). If the generalized ramp torque rapidly exceeds the defined upper and lower limits within a short period of time (0.5-2 seconds), the vehicle is considered to have met the second slip condition.

[0053] Condition three: The vehicle's longitudinal acceleration signal is measured by the vehicle's sensors based on the vehicle's motion state. Under normal circumstances, the vehicle's longitudinal acceleration varies within a certain range (−0.5g to 0.8g). If the transmission output shaft speed increases rapidly within a short period of time (0.5-2s) and exceeds the calibrated value, and the change in the vehicle's longitudinal acceleration is within the calibrated range, the vehicle can be determined to have met condition three for slippage.

[0054] Furthermore, the transmission output shaft speed change rate of condition 1 is The calculation formula is as follows:

[0055] (1)

[0056] In formula (1):

[0057] for The transmission output shaft speed at time t;

[0058] for The transmission output shaft speed at time .

[0059] Furthermore, the calculation process of the generalized ramp torque described in condition 2 is as follows:

[0060] S201: The engine input torque signal is processed by the torque converter torque multiplication module to obtain the transmission input shaft torque (i.e., the torque output from the torque converter to the transmission, which includes the torque multiplication effect).

[0061] S202: Calculate traction torque :

[0062] (2)

[0063] In formula (2):

[0064] is the transmission input shaft torque;

[0065] is the gear ratio;

[0066] is the main reducer speed ratio;

[0067] is gear efficiency;

[0068] S203: Calculate generalized ramp torque :

[0069] (3)

[0070] In formula (3):

[0071] for road resistance;

[0072] is wind resistance;

[0073] is the acceleration resistance;

[0074] is the wheel rolling radius.

[0075] 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 embodied in other forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0076] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for detecting slippage and controlling gear position of a vehicle equipped with an automatic transmission, characterized in that: The method comprises the following steps: S1: The signal input module receives the input signal through the vehicle CAN communication network and calls the transmission output shaft speed and transmission torque converter torque increase parameters for pre-processing; S2: The road condition diagnosis module determines whether the vehicle is skidding. If it is determined that the vehicle is skidding, it proceeds to S3; S3: TCU enters the gear processing module to fix the current gear; S4: When the gear is held in a fixed position for a preset time until the slipping condition is no longer met, the limited gear mode is exited; or when the driver switches to M gear or other modes during the gear holding period, the limited gear mode is exited.

2. The method for detecting slippage and controlling gear position of a vehicle equipped with an automatic transmission according to claim 1, wherein: The input signals in S1 include the longitudinal acceleration, wheel speed, throttle, gear lever position and engine input torque signal of the vehicle.

3. The method for detecting slippage and controlling gear position of a vehicle equipped with an automatic transmission according to claim 1, wherein: The determination condition of whether the vehicle is slipping in S2 is that at least one of the following slip conditions is met and the vehicle speed is lower than the calibrated low speed threshold, and the slip conditions are: Condition 1: The transmission output shaft speed change rate exceeds the calibration threshold; Condition 2: The generalized ramp torque exceeds the preset upper and lower limits; Condition three: The transmission output shaft speed exceeds the calibrated value and the longitudinal acceleration change of the vehicle is less than the calibrated range.

4. The method for detecting slippage and controlling gear position of a vehicle equipped with an automatic transmission according to claim 3, wherein: Condition 1: Transmission output shaft speed change rate The calculation formula is as follows: （1） In formula (1): for The transmission output shaft speed at time ; for The transmission output shaft speed at time .

5. The method for detecting slippage and controlling gear position of a vehicle equipped with an automatic transmission according to claim 3, wherein: The calculation process of the generalized ramp torque described in condition 2 is as follows: S201: The engine input torque signal is processed by the torque converter torque multiplication module to obtain the transmission input shaft torque; S202: Calculate traction torque : （2） In formula (2): is the transmission input shaft torque; is the gear ratio; is the main reducer speed ratio; is gear efficiency; S203: Calculate generalized ramp torque : （3） In formula (3): for road resistance; is wind resistance; is the acceleration resistance; is the wheel rolling radius.

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