AMT gear shifting synchronization process control system and control method

Abstract

The invention discloses a commercial vehicle AMT gear shifting synchronization process control system and method.The control system comprises an engine rotating speed sensor, a TCU, a CAN bus, an ECU and a fuel injection executor, the engine rotating speed sensor is used for measuring engine rotating speed information and sending the information to the ECU; the first input end of the ECU is connected with the output end of the engine rotating speed sensor, and the second input end of the ECU is connected with the CAN bus; the first output end of the ECU is connected with the CAN bus; a second output end of the ECU is connected with the fuel injection actuator; the input end of the TCU is connected with the CAN bus; and the output end of the TCU is connected with the CAN bus. According to the method, the speed reduction speed of the engine can be effectively reduced, the rotating speed falling and fluctuation phenomena in the AMT gear shifting process are avoided, and the gear shifting smoothness and comfort are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vehicle transmission control, and particularly relates to an AMT gear shifting synchronization process control system and a control method. BACKGROUND

[0002] For a commercial vehicle model equipped with a mechanical automatic transmission (AMT), the entire upshift process of the vehicle is roughly as follows: the engine receives a throttle signal, the engine speed is raised, when the engine speed reaches the upshift speed, the AMT sends out a target gear, then the clutch is disengaged and the gear shifting operation is completed, after that, the input shaft is braked by the brake to reduce the speed and reach the appropriate speed difference condition, and then the AMT engages the gear. At the same time, during the synchronization process from the end of the AMT gear shifting to the beginning of the gear engagement (also known as the gear shifting synchronization stage), the engine will stop fuel injection and naturally reduce the speed to reach the speed condition synchronized with the input shaft, and then the clutch is smoothly engaged to complete the entire upshift process. In this process, the appropriate natural engine speed reduction speed is of great help to the smoothness, comfort and power of the gear shifting.

[0003] However, during the AMT and vehicle matching calibration process, the engine natural speed reduction is too fast, so when the AMT completes the gear engagement in the gear shifting synchronization process, the engine speed is already much lower than the input shaft speed of the AMT, at this time the clutch is engaged, which will cause speed drop and fluctuation, and then cause gear shifting jerk and vehicle surging, which seriously affects the gear shifting comfort and smoothness. The natural engine speed reduction speed is affected by many factors, such as the engine flywheel moment of inertia, friction loss during piston reciprocating motion, operation load of many electrical accessories such as compressor, oil pump, water pump, air conditioner and the like, which will affect the natural engine speed reduction speed. Therefore, different engines have different speed reduction speeds, and the same engine also has varying speed reduction speeds under different operating conditions.

[0004] In order to solve the problem of poor AMT gear shifting smoothness and comfort caused by too fast natural engine speed reduction in the AMT upshift synchronization process, a new AMT gear shifting synchronization process control technology is urgently needed. SUMMARY

[0005] The purpose of the present application is to provide a commercial vehicle AMT gear shifting synchronization process control system and control method to solve the problem of poor AMT gear shifting smoothness and comfort caused by too fast natural engine speed reduction in the AMT upshift synchronization process.

[0006] In order to achieve the above purpose, the technical scheme is adopted as follows:

[0007] In one aspect, the application provides a commercial vehicle AMT shift synchronization process control system, characterized in that it comprises an engine speed sensor, a TCU, a CAN bus, an ECU and a fuel injection actuator, wherein:

[0008] The engine speed sensor is used to measure engine speed information and send the information to the ECU;

[0009] The first input end of the ECU is connected with the output end of the engine speed sensor for receiving engine speed signals; the second input end of the ECU is connected with the CAN bus for receiving torque request commands sent by the TCU on the CAN bus and judging whether to perform in-cylinder fuel injection; the first output end of the ECU is connected with the CAN bus for transmitting engine torque signals and engine speed signals to the TCU; and the second output end of the ECU is connected with the fuel injection actuator for controlling the fuel injection actuator to perform fuel injection operation.

[0010] The input end of the TCU is connected with the CAN bus for receiving engine speed signals and engine torque signals sent by the ECU on the CAN bus and processing the received signals; and the output end of the TCU is connected with the CAN bus for sending torque request commands to the ECU.

[0011] Further, the TCU is installed on the transmission housing and connected on the CAN bus through the vehicle wiring harness, the ECU is installed on the vehicle frame and connected on the CAN bus through the vehicle wiring harness, and the engine speed sensor is installed on the engine flywheel housing and connected with the ECU through the engine wiring harness.

[0012] In another aspect, the application provides a commercial vehicle AMT shift synchronization process control method based on the commercial vehicle AMT shift process control system of the application, which specifically comprises the following steps:

[0013] Step 1: The engine speed sensor measures the engine speed in real time and sends the engine speed to the ECU; the ECU sends engine speed signals to the CAN bus;

[0014] Step 2: The TCU judges whether the AMT is in the shift synchronization stage, if yes, step 3 is executed; otherwise, the AMT performs shift according to the current shift strategy and returns to step 1;

[0015] Step 3: The TCU obtains engine speed information from the CAN bus, calculates the engine speed drop Δn and the engine natural speed drop slope k within Δt time according to the engine speed information;

[0016] When k≤K0, it is judged that the engine natural speed drop is normal, the AMT performs shift according to the current shift strategy and returns to step 1; wherein K0 is an empirical value of the engine natural speed drop slope k.

[0017] When k>K0, it is judged that the natural engine speed reduction is too fast, at this time the TCU sends a torque request to the CAN bus, and the value of the requested torque in the torque request increases with the increase of the natural engine speed reduction slope k; step 4 is entered;

[0018] In step 4, the ECU receives the torque request of the TCU in real time through the CAN bus, when receiving the torque request sent by the TCU, the ECU calculates the fuel injection amount according to the size of the requested torque in the torque request, and then sends an engine fuel injection instruction to the fuel injection executor, and then returns to step 2 until the value of the engine speed reduction rate k becomes smaller until it meets the requirement of the TCU, that is, k=K0, at this time the method of the application ends.

[0019] Further, in step 3, the calculation formula of the natural engine speed reduction slope k is as follows:

[0020] k=Δn / Δt

[0021] In the formula:

[0022] Δt is a preset time, unit: s;

[0023] Δn is the natural reduction of engine speed in Δt time, unit: rpm;

[0024] k is the natural engine speed reduction slope, unit: rpm / s.

[0025] Further, in step 4, K0=700rpm / s.

[0026] Compared with the prior art, the present application has the following beneficial technical effects:

[0027] In the present application, the TCU judges whether the natural engine speed reduction speed is appropriate through the engine speed information on the CAN bus during the shift synchronization process, and then requests torque from the ECU when the speed reduction speed is too fast, and the engine cylinder is injected, so as to control the opening and closing time of the injection during the shift process, and to slow down the engine speed reduction speed by means of the engine cylinder injection during the shift process, thereby avoiding the problems of poor shift smoothness and poor comfort caused by the too fast engine speed reduction during the AMT upshift process, and effectively improving the shift smoothness and comfort. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a structure diagram of the commercial vehicle AMT shift synchronization process control system of the present application.

[0029] Figure 2 It is an engine speed comparison diagram under the conditions of cylinder injection and no injection when the natural engine speed reduction is too fast during the AMT upshift synchronization process.

[0030] The present invention is further explained below with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0031] like Figure 1 As shown, the commercial vehicle AMT shift synchronization process control system provided by the present invention includes an engine speed sensor, an AMT transmission controller (TCU), a CAN bus, an engine controller (ECU) and a fuel injection actuator, wherein:

[0032] The engine speed sensor is used to measure the engine speed information and send the information to the ECU;

[0033] The first input terminal of the ECU is connected to the output terminal of the engine speed sensor for receiving the engine speed signal; the second input terminal of the ECU is connected to the CAN bus for receiving the torque request command sent by the TCU on the CAN bus and determining whether to perform in-cylinder fuel injection; the first output terminal of the ECU is connected to the CAN bus for transmitting the engine torque signal and the engine speed signal to the TCU; the second output terminal of the ECU is connected to the fuel injection actuator for controlling the fuel injection actuator to perform fuel injection operation.

[0034] The input end of the TCU is connected to the CAN bus, and is used to receive the engine speed signal and engine torque signal sent by the ECU on the CAN bus, and process the received signals; the output end of the TCU is connected to the CAN bus, and is used to send a torque request command to the ECU.

[0035] Specifically, the TCU is installed on the transmission housing and connected to the CAN bus through the vehicle wiring harness, the ECU is installed on the frame and connected to the CAN bus through the vehicle wiring harness, and the engine speed sensor is installed on the engine flywheel housing and connected to the ECU through the engine wiring harness.

[0036] The commercial vehicle AMT shift process control method provided by the present invention is based on the commercial vehicle AMT shift process control system of the present invention, and includes the following steps:

[0037] Step 1: The engine speed sensor measures the engine speed in real time and sends the engine speed to the ECU; the ECU sends the engine speed signal to the CAN bus.

[0038] Step 2: The TCU determines whether the AMT is in the shift synchronization phase. If so, the system proceeds to step 3. Otherwise, the AMT executes the shift according to the current shift strategy and the system returns to step 1.

[0039] Step 3, the TCU obtains the engine speed information from the CAN bus, and calculates the engine speed drop Δn and the engine natural speed drop slope k in the Δt time according to the engine speed information, and the calculation formula is as follows:

[0040] k = Δn / Δt

[0041] In the formula,

[0042] Δt is the preset time, and the unit is s.

[0043] Δn is the engine natural speed drop in the Δt time, and the unit is rpm.

[0044] k is the engine natural speed drop slope, and the unit is rpm / s.

[0045] When k≤K0, it is judged that the engine natural speed drop is normal, the AMT performs the gear shifting according to the current gear shifting strategy, and returns to step 1; wherein K0 is an experience value of the engine natural speed drop slope k (700 rpm / s in the embodiment)

[0046] When k>K0, it is judged that the engine natural speed drop is too fast, at this time, the TCU sends a torque request to the CAN bus, and the value of the requested torque in the torque request increases with the increase of the engine natural speed drop slope k. Step 4 is entered.

[0047] Step 4, the ECU receives the torque request of the TCU in real time through the CAN bus, when receiving the torque request sent by the TCU, the ECU calculates the fuel injection amount according to the size of the requested torque in the torque request, and then sends an engine fuel injection instruction to the fuel injection executor; then the engine is injected and combusted, so that the torque increases, and the value of the engine speed drop rate k becomes smaller. Then return to step 2 until the value of the engine speed drop rate k becomes smaller until the TCU requirement is met (i.e. k=K0, 700 rpm / s). At this time, the method of the application ends.

[0048] In a preferred embodiment of the application, the preset time Δt is set to 0.01 s, and the reasonable experience value K0 of the engine natural speed drop slope is set to 700 rpm / s.

[0049] The implementation of the AMT gear shifting synchronization process control system provided by the application is as follows Figure 2As shown in the figure (the black line represents the prior art, and the red line represents the processing logic of the method of the present invention), during the AMT upshift synchronization phase, the engine naturally decelerates too quickly. As the transmission completes the gear shift and engages the clutch, the engine speed drops and fluctuates due to the low engine speed, which in turn causes shift jerk and vehicle jerk. When the engine decelerates too quickly, in-cylinder fuel injection control during the shift synchronization process slows the engine deceleration rate. When the engine speed is appropriate, the clutch engages, thus avoiding speed drops and fluctuations and improving the smoothness and comfort of AMT shifts.

Claims

1. A commercial vehicle AMT shift synchronization process control system, characterized in that: It includes engine speed sensor, TCU, CAN bus, ECU and fuel injection actuator, including: The engine speed sensor is used to measure the engine speed information and send the information to the ECU; The first input terminal of the ECU is connected to the output terminal of the engine speed sensor for receiving the engine speed signal; the second input terminal of the ECU is connected to the CAN bus for receiving the torque request command sent by the TCU on the CAN bus and determining whether to perform in-cylinder fuel injection; the first output terminal of the ECU is connected to the CAN bus for transmitting the engine torque signal and the engine speed signal to the TCU; the second output terminal of the ECU is connected to the fuel injection actuator for controlling the fuel injection actuator to perform fuel injection operation; The input end of the TCU is connected to the CAN bus, and is used to receive the engine speed signal and engine torque signal sent by the ECU on the CAN bus, and process the received signals; the output end of the TCU is connected to the CAN bus, and is used to send a torque request command to the ECU.

2. The commercial vehicle AMT shift synchronization process control system according to claim 1, characterized in that: The TCU is installed on the transmission housing and connected to the CAN bus through the vehicle wiring harness. The ECU is installed on the vehicle frame and connected to the CAN bus through the vehicle wiring harness. The engine speed sensor is installed on the engine flywheel housing and connected to the ECU through the engine wiring harness.

3. A commercial vehicle AMT shift synchronization process control method, characterized in that: The commercial vehicle AMT shift process control system based on the present invention specifically includes the following steps: Step 1: The engine speed sensor measures the engine speed in real time and sends the engine speed to the ECU; the ECU sends the engine speed signal to the CAN bus; Step 2: The TCU determines whether the AMT is in the shift synchronization phase. If so, the system proceeds to step 3. Otherwise, the AMT executes the shift according to the current shift strategy and the system returns to step 1. Step 3: The TCU obtains engine speed information from the CAN bus and calculates the engine speed drop Δn and the engine natural speed drop slope k within the time Δt based on the engine speed information. When k≤K0, it is determined that the engine's natural deceleration is normal, and the AMT performs the shift according to the current shift strategy, returning to step 1; where K0 is the empirical value of the engine's natural deceleration slope k; When k>K0, it is determined that the engine is decelerating too quickly. At this time, the TCU sends a torque request to the CAN bus. The value of the requested torque in the torque request increases as the engine deceleration slope k increases. Go to step 4. In step 4, the ECU receives the torque request from the TCU in real time via the CAN bus. Upon receiving the torque request from the TCU, the ECU calculates the injection amount based on the magnitude of the requested torque in the torque request, and then sends the engine injection command to the fuel injection actuator. The process then returns to step 2 until the engine speed reduction rate k decreases to meet the TCU requirement, i.e., k=K0. At this point, the method of the present invention ends.

4. The commercial vehicle AMT shift synchronization process control method according to claim 3, characterized in that: In step 3, the calculation formula of the engine natural speed reduction slope k is as follows: k=Δn / Δt Where: Δt—preset time, unit is s; Δn—the natural decrease in engine speed during Δt, in rpm; k—engine natural deceleration slope, in rpm / s.

5. The commercial vehicle AMT shift synchronization process control method according to claim 3, characterized in that: In step 4, K0 = 700 rpm / s.

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