A control method for automatic starting of a commercial vehicle AMT

Abstract

The present invention provides a method for controlling the automatic start of a commercial vehicle AMT, including a control state model and the jump conditions of the control state model. Through the collaborative control of the vehicle control system, the transmission control system, the engine control system and the handle control system, when the vehicle is in the D / R gear position, releasing the foot brake and not stepping on the accelerator, the transmission control system controls the clutch to automatically engage, and the vehicle travels stably at a low speed. When the vehicle encounters other harsh working conditions with large driving resistances such as a large slope, in order to avoid the risk of engine stalling, the engagement depth of the clutch is adjusted in real time to ensure the power response and driving smoothness of the vehicle's automatic start condition, and enhance the driver's control performance.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission control, and particularly to an automatic starting control method for a commercial vehicle AMT. Background Art

[0002] According to market research and analysis, the domestic AMT product market has entered a period of rapid development. At the same time, drivers have higher and higher requirements for the drivability of heavy trucks. The operating environment of heavy trucks is generally relatively harsh. In working conditions such as construction sites, freight stations, and urban traffic jams, the vehicle needs to travel at a low speed. The driver frequently operates the accelerator and brake, and the vehicle speed is very difficult to control, which easily causes driver fatigue. In order to enhance the vehicle's handling performance, an automatic starting function is developed to reduce the driving fatigue intensity. However, many AMT commercial vehicles on the market currently do not have this function or there are still the following problems with this function:

[0003] 1. The vehicle's power response is slow and there is a starting impact during the automatic starting condition. When the vehicle encounters a large driving resistance condition, it is easy to cause the engine to stall. After the engine speed "drops into a pit", the engine anti-stall strategy is triggered, and the torque increases rapidly, causing the vehicle to lunge forward, presenting a safety hazard;

[0004] 2. The automatic starting function does not correct the engine requested speed according to factors such as engine water temperature and altitude. The engine's idle torque capacity is poor, and the clutch separation is frequently triggered, resulting in the vehicle "hunting" phenomenon, and the driving experience is very poor. Summary of the Invention

[0005] The present invention proposes an automatic starting control method for a commercial vehicle AMT. Through the collaborative control of the vehicle control system, transmission control system, engine control system, and handle control system, when the vehicle is in the D / R gear position, the foot brake is released and the accelerator is not stepped on, the transmission control system controls the clutch to automatically engage, and the vehicle travels stably at a low speed. When the vehicle encounters other harsh conditions with large driving resistances such as a large slope, to avoid the risk of engine stalling, the clutch engagement depth is adjusted in real time to ensure the power response and driving smoothness during the vehicle's automatic starting condition, and enhance the driver's handling performance.

[0006] To solve the problems in the above background art, the present invention is realized through the following technical solutions:

[0007] An automatic starting control method for a commercial vehicle AMT, including a control state model; the control state model includes:

[0008] S1. System initialization state: Calculate the vehicle state and determine whether the state of the vehicle before entering automatic starting is stationary or high-speed coasting;

[0009] S2. Establish the base torque: The clutch requested torque increases to the semi-engagement point torque at a certain slope, and during this process, the vehicle shake cannot be felt.

[0010] S3. Rotational speed PID control: Calculate the requested torque of the closed-loop part of the clutch through the difference between the rotational speed of the transmission input shaft and the target engine idle speed.

[0011] S4. Vehicle speed maintenance: Enter this state when the rotational speed of the input shaft meets the target engine speed, maintain the clutch torque, and at the same time monitor the difference between the rotational speed of the transmission input shaft and the target engine idle speed. When the difference exceeds the calibrated threshold, activate the rotational speed PID control state.

[0012] S5. Anti-stall: When the engine speed decrease rate is greater than the calibrated threshold, reduce or maintain the clutch engagement slope. When the engine speed resumes to the target value, this state jumps to the rotational speed PID control state.

[0013] S6. Maintain low torque: This state is activated when the clutch torque increases to the maximum torque, but the vehicle remains stationary for the calibrated holding time. The ramp condition is easily triggered because the wheel-end friction force is in the reverse direction, which can reduce the clutch torque and the frictional work, but the vehicle cannot roll back. In this state, the clutch is always in the slip friction state. To protect the clutch, if the driver does not step on the brake, it will be forced to exit after a certain period of time.

[0014] S7. Roll back: This state is activated when the system detects that the gear and vehicle speed directions are opposite, and increase the clutch torque at a certain slope.

[0015] S8. Coasting: This state is activated when the vehicle coasts at a high speed to a certain speed. If the vehicle speed meets the target vehicle speed, maintain this state.

[0016] S9. Torque reduction: This state is activated when the system detects the trigger of the brake signal, and the clutch torque is reduced to the minimum torque.

[0017] Preferably, the jump conditions of the control state model are:

[0018] TR01: When the clutch torque is less than the normal clutch torque value for automatic start, jump from S1 to S2;

[0019] TR02: When the clutch torque is not less than the semi-engagement point torque value, jump from S2 to S3;

[0020] TR03: When the rotational speed of the transmission input shaft is synchronized with the target engine idle speed and the clutch torque is not less than the normal clutch torque value for automatic start, jump from S3 to S4;

[0021] TR04: When the actual rotational speed of the transmission input shaft is greater than the target engine speed by the calibrated threshold, jump from S4 to S3;

[0022] TR05: When the engine speed is less than the calibrated threshold, jump from S3 to S5;

[0023] TR06: When the engine speed is greater than the calibrated threshold, jump from S5 to S3;

[0024] TR07: When the transmission gear and the vehicle speed are in opposite directions, jump from S3 to S7;

[0025] TR08: When the vehicle stops or the transmission gear and the vehicle speed are in the same direction, jump from S7 to S3;

[0026] TR09: When the clutch torque is not less than the normal torque value for automatic start, jump from S1 to S8;

[0027] TR10: When the transmission input shaft speed is synchronized with the engine target idle speed and the clutch torque is not less than the normal clutch torque value for automatic start, jump from S8 to S4;

[0028] TR11: When the actual transmission input shaft speed and the target engine speed are greater than the calibrated threshold and the clutch torque is less than the normal torque value for automatic start, jump from S8 to S3;

[0029] TR12: When the actual transmission input shaft speed and the target engine speed are greater than the calibrated threshold and the clutch torque is less than the normal torque value for automatic start, jump from S3 to S7 and then from S7 to S4;

[0030] TR13: When the brake signal is detected and triggered, this condition has the highest priority. Regardless of the current state of the system, when this condition is detected and holds, jump to the torque reduction state, jump from S1 to S9;

[0031] TR14: When the clutch torque is not less than the semi - engagement point torque value, jump from S9 to S3;

[0032] TR15: When the transmission input shaft speed is synchronized with the engine target idle speed and the clutch torque is not less than the normal clutch torque value for automatic start, jump from S3 to S5 and then from S5 to S4;

[0033] TR16: When the clutch torque increases to the maximum torque, but the vehicle remains stationary for the calibrated holding time, jump from S4 to S3 and then from S3 to S6;

[0034] TR17: When the clutch torque is less than the minimum torque value for automatic start, jump from S1 to S9 and then return from S9 to S1.

[0035] Preferably, the requested torque of the clutch closed - loop part in S3 = the requested torque of the clutch in the previous cycle + the calculated torque of the clutch closed - loop part

[0036] The calculated torque of the clutch closed-loop part is calculated based on the reference speed, target speed, speed difference, and rate of change of speed difference; the reference speed is the target idle speed of the engine; the initial value of the target speed is zero and it increases to the reference speed at a certain slope; the speed difference of the proportional part and the integral part = target speed - actual input shaft speed; the rate of change of speed difference of the differential part = (target speed - target speed of the previous cycle) - (current input shaft speed - input shaft speed of the previous cycle); when the speed percentage exceeds 100% or is close to 0%, the slope is set as small as possible to reduce the possible impact of clutch synchronization, and the speed percentage = (current speed × 100) ÷ target speed.

[0037] Preferably, the S7 backward rolling state is identified by the vehicle speed direction through the transmission output shaft speed sensor.

[0038] Preferably, it also includes idle compensation state control; when the altitude is high and the engine water temperature is low, the engine's ability to carry torque at idle is weak. Considering the power of engine accessories and the resistance when the vehicle just starts, a suitable engine idle compensation value is calibrated based on the above factors to improve the engine's ability to carry torque at idle.

[0039] Compared with the prior art, the present invention has the following beneficial technical effects:

[0040] Through the coordinated control of the vehicle control system, transmission control system, engine control system, and handle control system, when the vehicle is in the D / R gear position, when the foot brake is released and the accelerator is not pressed, the transmission control system controls the clutch to automatically engage, and the vehicle travels stably at low speed. When the vehicle encounters harsh working conditions such as large slopes and other large driving resistances, to avoid the risk of engine stalling, the clutch engagement depth is adjusted in real time to ensure the power response and driving smoothness of the vehicle's automatic start condition, and enhance the driver's control performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is the framework diagram of the automatic start function control system architecture of the present invention;

[0042] Figure 2 It is the PID calculation speed relationship diagram of the present invention;

[0043] Figure 3 It is the speed percentage calculation diagram of the present invention;

[0044] Figure 4 It is the framework diagram of the engine idle compensation principle of the automatic start function of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] Example 1

[0046] As Figures 1 to 3As shown, a method for controlling the automatic start of a commercial vehicle AMT includes a control state model; the control state model includes:

[0047] S1. System initialization state: Calculate the vehicle state and determine whether the state of the vehicle before entering the automatic start is stationary or high-speed coasting;

[0048] S2. Establish basic torque: The clutch requested torque increases to the half-engagement point torque at a certain slope. During this process, the whole vehicle vibration cannot be felt;

[0049] S3. Rotational speed PID control: Calculate the clutch closed-loop part requested torque through the difference between the rotational speed of the transmission input shaft and the target idle speed of the engine;

[0050] S4. Vehicle speed maintenance: Enter this state when the rotational speed of the input shaft meets the target engine speed. Maintain the clutch torque and monitor the difference between the rotational speed of the transmission input shaft and the target idle speed of the engine at the same time. When the difference exceeds the calibrated threshold, activate the rotational speed PID control state;

[0051] S5. Anti-stall: When the engine speed decline rate is greater than the calibrated threshold, reduce or maintain the clutch engagement slope. When the engine speed resumes to the target value, this state jumps to the rotational speed PID control state;

[0052] S6. Maintain low torque: This state is activated when the clutch torque increases to the maximum torque but the vehicle remains stationary for the calibrated holding time; The ramp condition is easily triggered because the wheel-end friction force is in the reverse direction, which can reduce the clutch torque and reduce the frictional work, but the vehicle cannot roll back. In this state, the clutch is always in the slip friction state. To protect the clutch, if the driver does not step on the brake, it will be forced to exit after a certain period of time;

[0053] S7. Roll back: This state is activated when the system detects that the gear and vehicle speed directions are opposite, and increase the clutch torque at a certain slope;

[0054] S8. Coasting: This state is activated when the vehicle coasts at a high speed to a certain vehicle speed. If the vehicle speed meets the target vehicle speed, maintain this state;

[0055] S9. Torque reduction: This state is activated when the system detects the trigger of the brake signal, and the clutch torque is reduced to the minimum torque.

[0056] The jump conditions of the control state model are:

[0057] TR01: When the clutch torque is less than the normal clutch torque value for automatic start, jump from S1 to S2;

[0058] TR02: When the clutch torque is not less than the half-engagement point torque value, jump from S2 to S3;

[0059] TR03: The transmission input shaft speed is synchronized with the engine target idle speed and the clutch torque is not less than the normal clutch torque value for automatic start. Jump from S3 to S4;

[0060] TR04: The actual transmission input shaft speed is greater than the calibrated threshold compared to the target engine speed. Jump from S4 to S3;

[0061] TR05: The engine speed is less than the calibrated threshold. Jump from S3 to S5;

[0062] TR06: The engine speed is greater than the calibrated threshold. Jump from S5 to S3;

[0063] TR07: The transmission gear is opposite to the vehicle speed direction. Jump from S3 to S7;

[0064] TR08: The vehicle stops or the transmission gear is in the same direction as the vehicle speed. Jump from S7 to S3;

[0065] TR09: The clutch torque is not less than the normal torque value for automatic start. Jump from S1 to S8;

[0066] TR10: The transmission input shaft speed is synchronized with the engine target idle speed and the clutch torque is not less than the normal clutch torque value for automatic start. Jump from S8 to S4;

[0067] TR11: The actual transmission input shaft speed is greater than the calibrated threshold compared to the target engine speed and the clutch torque is less than the normal torque value for automatic start. Jump from S8 to S3;

[0068] TR12: The actual transmission input shaft speed is greater than the calibrated threshold compared to the target engine speed and the clutch torque is less than the normal torque value for automatic start. Jump from S3 to S7 and then from S7 to S4;

[0069] TR13: The system detects that the brake signal is triggered. This condition has the highest priority. Regardless of the current state of the system, when this condition is detected to be true, it will jump to the torque reduction state. Jump from S1 to S9;

[0070] TR14: The clutch torque is not less than the half - engagement point torque value. Jump from S9 to S3;

[0071] TR15: The transmission input shaft speed is synchronized with the engine target idle speed and the clutch torque is not less than the normal clutch torque value for automatic start. Jump from S3 to S5 and then from S5 to S4;

[0072] TR16: The clutch torque increases to the maximum torque, but the vehicle remains stationary for the calibrated holding time. Jump from S4 to S3 and then from S3 to S6;

[0073] TR17: The clutch torque is less than the minimum torque value for automatic start. Jump from S1 to S9 and return from S9 to S1.

[0074] The requested torque of the clutch closed-loop part in S3 = the requested torque of the clutch in the previous cycle + the calculated torque of the clutch closed-loop part

[0075] The calculated torque of the clutch closed-loop part is calculated based on the reference speed, target speed, speed difference, and rate of change of speed difference. The reference speed is the target idle speed of the engine. The initial value of the target speed is zero and it increases to the reference speed at a certain slope. The speed difference of the proportional part and the integral part = target speed - actual input shaft speed. The rate of change of speed difference of the differential part = (target speed - target speed in the previous cycle) - (current input shaft speed - input shaft speed in the previous cycle). When the speed percentage exceeds 100% or approaches 0%, set the slope as small as possible to reduce the possible impact of clutch synchronization. The speed percentage = (current speed × 100) ÷ target speed.

[0076] The backward slipping state in S7 is identified by the speed sensor of the transmission output shaft for the vehicle speed direction.

[0077] Embodiment 2

[0078] It also includes the control of the idle compensation state. When the altitude is high and the engine water temperature is low, the torque-carrying capacity of the engine at idle is weak. Considering the power of the engine accessories and the resistance when the vehicle just starts, calibrate a suitable engine idle compensation value based on the above factors to improve the torque-carrying capacity of the engine at idle.

Claims

1. A method for controlling the automatic start of a commercial vehicle AMT, characterized in that: It includes a control state model; the control state model includes: S1. System initialization state: Calculate the vehicle state and determine whether the state of the vehicle before entering automatic start is stationary or high-speed coasting. S2. Establish basic torque: The clutch requested torque increases to the semi-engagement point torque at a certain slope, and during this process, the whole vehicle shake cannot be felt. S3. Rotational speed PID control: Calculate the clutch closed-loop part requested torque through the difference between the transmission input shaft rotational speed and the engine target idle speed. S4. Vehicle speed maintenance: Enter this state when the input shaft rotational speed meets the target engine rotational speed, maintain the clutch torque, and at the same time monitor the difference between the transmission input shaft rotational speed and the engine target idle speed. When the difference exceeds the calibrated threshold, activate the rotational speed PID control state. S5. Anti-stall: When the engine rotational speed decrease rate is greater than the calibrated threshold, reduce or maintain the clutch engagement slope. When the engine rotational speed returns to the target value, this state jumps to the rotational speed PID control state. S6. Maintain low torque: This state is activated when the clutch torque increases to the maximum torque, but the vehicle remains stationary for the calibrated holding time. The ramp condition is easily triggered because the wheel-end friction force is in the reverse direction, which can reduce the clutch torque and reduce the friction work, but the vehicle cannot roll back. In this state, the clutch is always in the slip friction state. To protect the clutch, if the driver does not step on the brake, it will be forced to exit after maintaining for a period of time. S7. Roll back: This state is activated when the system detects that the gear and vehicle speed directions are opposite, and increase the clutch torque at a certain slope. S8. Coasting: This state is activated when the vehicle coasts at a high speed to a certain vehicle speed. If the vehicle speed meets the target vehicle speed, maintain this state. S9. Torque reduction: This state is activated when the system detects the trigger of the brake signal, and the clutch torque is reduced to the minimum torque. The jump conditions of the control state model are: TR01: When the clutch torque is less than the normal clutch torque value for automatic start, jump from S1 to S2. TR02: When the clutch torque is not less than the semi-engagement point torque value, jump from S2 to S3. TR03: When the transmission input shaft rotational speed and the engine target idle speed are synchronized and the clutch torque is not less than the normal clutch torque value for automatic start, jump from S3 to S4. TR04: When the actual transmission input shaft rotational speed and the target engine rotational speed are greater than the calibrated threshold, jump from S4 to S3; TR05: When the engine rotational speed is less than the calibrated threshold, jump from S3 to S5. TR06: When the engine rotational speed is greater than the calibrated threshold, jump from S5 to S3. TR07: When the transmission gear and the vehicle speed directions are opposite, jump from S3 to S7. TR08: When the vehicle stops or the transmission gear and the vehicle speed directions are the same, jump from S7 to S3. TR09: When the clutch torque is not less than the normal torque value for automatic start, jump from S1 to S8. TR10: When the transmission input shaft rotational speed and the engine target idle speed are synchronized and the clutch torque is not less than the normal clutch torque value for automatic start, jump from S8 to S4. TR11: When the actual transmission input shaft rotational speed and the target engine rotational speed are greater than the calibrated threshold and the clutch torque is less than the normal torque value for automatic start, jump from S8 to S3. TR12: When the actual input shaft speed of the transmission is greater than the calibrated threshold value of the target engine speed and the clutch torque is less than the normal torque value for automatic start, jump from S3 to S7 and then from S7 to S4; TR13: When the system detects the trigger of the brake signal, this condition has the highest priority. Regardless of the current state of the system, when this condition is detected to be true, it jumps to the torque reduction state and from S1 to S9; TR14: When the clutch torque is not less than the half-engagement point torque value, jump from S9 to S3; TR15: When the transmission input shaft speed is synchronized with the engine target idle speed and the clutch torque is not less than the normal clutch torque value for automatic start, jump from S3 to S5 and then from S5 to S4; TR16: When the clutch torque increases to the maximum torque, but the vehicle remains stationary for the calibrated holding time, jump from S4 to S3 and then from S3 to S6; TR17: When the clutch torque is less than the minimum torque value for automatic start, jump from S1 to S9 and then return from S9 to S1.

2. The AMT automatic starting control method for commercial vehicles according to claim 1, characterized in that, The clutch closed-loop part request torque in S3 = the clutch request torque in the previous cycle + the clutch closed-loop part calculated torque. The clutch closed-loop part calculated torque includes calculations based on the reference speed, target speed, speed difference, and speed difference change rate; the reference speed is the engine target idle speed; the initial value of the target speed is zero and it increases to the reference speed at a certain slope; The proportional part and integral part speed difference = target speed - actual input shaft speed; The differential part speed difference change rate = (target speed - target speed in the previous cycle) - (current input shaft speed - input shaft speed in the previous cycle); When the speed percentage exceeds 100% or is close to 0%, set the slope as small as possible to reduce the possible impact of clutch synchronization. The speed percentage = (current speed × 100) ÷ target speed.

3. The AMT automatic starting control method for commercial vehicles according to claim 1, characterized in that The reverse state in S7 is to identify the vehicle speed direction through the transmission output shaft speed sensor.

4. The AMT automatic starting control method for commercial vehicles according to claim 1, wherein It also includes idle compensation state control; when the altitude is high and the engine water temperature is low, the engine's ability to carry torque at idle is weak. Considering the power of engine accessories and the resistance when the vehicle starts, calibrate a suitable engine idle compensation value to improve the engine's ability to carry torque at idle.

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