Commercial vehicle AMT brake performance and service life testing method

Abstract

The invention relates to the technical field of transmission testing, in particular to a commercial vehicle AMT (automated mechanical transmission) brake performance and service life testing method, which comprises the following steps of: 1, mounting an AMT gearbox on a rack meeting experimental conditions, and connecting the AMT gearbox with a motor through a clutch; 2, building a test model through MATLAB Simulink, generating a C code, integrating underlying software by using HighTec, generating an executable file, and flashing the executable file into a TCU (Transmission Control Unit); 3, the upper computer interacts with the TCU, and data representing the test process and result are sent through a CAN bus and displayed on an interface of the upper computer. According to the method, MATLAB Simulink is used for building a test model and generating a C code, an executable file is produced after integration, and automatic testing is achieved through CAN signal and UDS interaction; the TCU controls the electromagnetic valve through the wiring harness, so that the execution mechanism is controlled through compressed air to achieve separation and combination of the clutch and braking of the TB, the TCU autonomously executes instructions and performs cyclic testing, manual intervention is not needed, the single-time testing time is remarkably shortened, and then the testing efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission testing, and in particular to a method for testing the performance and life of an AMT brake on a commercial vehicle. Background Art

[0002] AMT is a transmission system that automatically shifts gears based on the vehicle's operating status and road conditions. It significantly improves vehicle comfort and effectively reduces driver workload. Currently, AMT penetration in the European and American commercial vehicle markets is nearing 100%. In China, this figure is nearing 30% by early 2024 and is rapidly growing.

[0003] Currently, mainstream AMTs in China all utilize a dual-intermediate shaft plus a sliding sleeve mechanical structure. Compared to synchronizers, sliding sleeves offer significant advantages, including simplicity, cost-effectiveness, and reliable quality. However, during the speed synchronization process during upshifts, there are significant differences between sliding sleeves and synchronizers. After an AMT upshifts, the transmission ratio decreases, and the input shaft speed must be reduced to match the current vehicle speed. Therefore, the AMT requires the transmission brake (TB) to provide braking force to reduce the input shaft speed and achieve synchronization.

[0004] CN117268619A discloses a method for offline detection of an AMT intermediate shaft brake system. The detection includes three parts: the first part is the braking function and performance of the brake system; the second part is whether the brake system resets normally after braking; and the third part is the response time of the brake system after braking and then releasing. The above three parts all request the speed and torque of the driving motor, and each part controls the activation or deactivation of the brake system respectively. The function, performance and consistency of the brake system are judged by the change rate, trend and change time of the intermediate shaft speed to see whether they meet the requirements, thereby detecting whether the relevant components of the intermediate shaft brake system are normal.

[0005] Among them, the offline detection device is not equipped with a clutch, and the brake system detection is carried out in the AMT neutral state, without performing the gear shifting action, which reduces the steps of manual judgment of the gear shifting operation, saves labor and improves efficiency; through the communication request interaction between the AMT controller and the drive motor, the function and performance detection of all relevant components of the AMT intermediate shaft brake system are completed.

[0006] An integrated mid-sized truck AMT (such as Figure 4The operating principle of the TB is as follows: When the TB is braking, a solenoid valve opens the intake and closes the exhaust ducts. Compressed air enters the TB cylinder, creating positive pressure on the brake piston, which compresses the steel plate against the friction plate, generating friction torque. The steel plate becomes stuck in the cylinder and cannot rotate freely. The friction plate is connected to the intermediate shaft via a spline, which is in constant mesh with the input shaft. The braking torque generated by the steel and friction plates provides braking force for the input shaft. When the TB is not braking, the solenoid valve closes the intake and opens the exhaust ducts. The return spring pushes the brake piston away, eliminating the friction torque between the steel and friction plates. TB performance directly impacts the AMT's shift synchronization process. Better TB performance leads to more stable upshift synchronization, improved shift quality, and enhanced vehicle comfort. Current TB performance testing methods rely primarily on operator control of the relevant solenoid valves or manual analysis of TB performance parameters through data processing, making automated testing impossible. Therefore, designing and developing a high-performance, stable, and reliable TB is a crucial task in AMT development. Summary of the Invention

[0007] In response to the problems in the prior art, the present invention provides a commercial vehicle AMT brake performance and life testing method to achieve automated testing of TB performance and life tests.

[0008] The present invention is achieved through the following technical solutions: A commercial vehicle AMT brake performance and life testing method comprises the following steps: Step 1: Install the AMT gearbox on a test bench that meets the experimental conditions and connect it to the motor through a clutch; Step 2: Build the test model using MATLAB Simulink, generate C code, integrate the underlying software using HighTec, generate an executable file, and flash it to the TCU. Step 3: The host computer interacts with the TCU, and the data representing the test process and results are sent via the CAN bus and displayed on the host computer interface.

[0009] Preferably, in step 1, the experimental conditions provided by the test bench for the test include: 24V DC power supply and 8±0.5bar compressed air.

[0010] Preferably, in step 2, the specific test steps in the executable file are: S21, the host computer sends a command to the TCU to start the test; In step S22, the TCU determines whether the experimental conditions are met. If so, it proceeds to step S23. Otherwise, it waits for the experimental conditions to be met before proceeding to step S21. S23, the TCU controls the clutch actuator to exhaust air, causing the clutch to engage; In step S24, the TCU determines whether the speed of the first gearbox shaft has reached the preset value. If so, it proceeds to step S25. Otherwise, it proceeds to step S23 to continue exhausting and engaging the clutch. If the exhaust time exceeds 10 seconds and the speed of the first gear shaft still does not meet the preset value, an error is reported, the clutch solenoid valve is closed, and the test is exited. S25, TCU controls the clutch actuator to intake air and push the clutch to disengage; In step S26, the TCU determines whether the clutch has reached the set disengagement position based on the received clutch displacement signal. If so, it proceeds to step S27; otherwise, it proceeds to step S25 to continue disengaging the clutch. If the clutch still has not reached the set disengagement position after the intake time exceeds 10 seconds, an error is reported, the clutch solenoid valve is closed, and the test is exited. S27, open the TB solenoid valve and set the preset value; S28, TCU determines whether the TB performance meets the design requirements. If so, the number of successes is increased by 1 and the next test is entered. Otherwise, the number of failures is increased by 1 and the next test is entered. When the cumulative number of successes reaches the design value, the life test passes.

[0011] Preferably, in S22, the experimental conditions include: the air source pressure is maintained between 7-8.5 bar, the neutral position of the gearbox, and the motor speed is maintained at 1800±100 rpm.

[0012] Preferably, in S24, the preset value is 1800±100 rpm.

[0013] Preferably, in S25, before intake, the TCU first controls the clutch solenoid valve to close for 3 seconds and then open it.

[0014] Preferably, in S27, the preset value is 200ms.

[0015] Preferably, in S28, the TCU determines whether the TB performance meets the design requirements based on the response time, braking slope, and exit time. The response time is the time from when the TCU issues a command for the TB solenoid valve to work to when the input shaft speed changes from natural deceleration to braking deceleration, recorded as t0~t1; the braking slope is the rate of change of the shaft speed during braking deceleration, t1~t2 is the direct rate of change; the exit time is the time from when the TCU issues a command for closing the TB solenoid valve to when the input shaft speed changes from braking deceleration to natural deceleration, recorded as t2~t3.

[0016] Preferably, in step 3, the host computer interacts with the TCU via UDS or XCP.

[0017] A commercial vehicle automatic transmission (AMT) brake performance and life test system includes a test bench, a clutch, a transmission control unit (TCU), a speed sensor, a displacement sensor, a compressed air control actuator, a solenoid valve, and a host computer. The test bench uses a motor controller to control the motor, providing torque and speed for the rear-end clutch. The clutch is installed between the AMT transmission and the test bench, and the TCU controls the disengagement and engagement of the clutch, transmitting the motor's power to the transmission input shaft. The speed sensor on the AMT transmission detects the transmission input shaft's speed, and the displacement sensor detects the shifting displacement and clutch displacement signals. The sensors transmit the signals to the TCU via a wiring harness. The TCU controls the solenoid valve via the wiring harness, thereby controlling the actuator via compressed air to achieve clutch disengagement and engagement, as well as TB braking. The TCU and the host computer are connected and communicate with each other via a CAN line. The test bench provides the AMT transmission with dry compressed air at 8±0.5 bar and a 24V DC power supply. The compressed air requires an air tank with a capacity of at least 10L in front, and the air supply pipe has an inner diameter of at least 11mm.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This method for testing the performance and life of commercial vehicle AMT brakes uses MATLAB Simulink to build a test model and generate C code. This integrated model produces an executable file, which is then flashed to the TCU. Automated testing is achieved through CAN signals and UDS interaction. The TCU controls the solenoid valve via a wiring harness, which in turn controls the actuator via compressed air to disengage and engage the clutch and brake the transmission. The TCU autonomously executes commands and conducts cyclic testing without manual intervention, significantly reducing single test time and improving testing efficiency. The equipment, test bench, and transmission used in this system can be reused for other tests and is suitable for testing transmissions of various AMT products.

[0019] Furthermore, during the test, the TCU performs multi-level judgments through a closed-loop feedback mechanism formed by the input shaft speed and clutch displacement signals, and quantitatively evaluates TB performance using multi-dimensional indicators.

[0020] Furthermore, the power supply and compressed air settings are used to simulate the vehicle environment as much as possible, so that the working state of the TB during the test is consistent with the actual gear shifting, ensuring the stability of the experimental conditions and thus the accuracy of the test results.

[0021] Furthermore, during the test, the clutch solenoid valve was closed for 3 seconds before the clutch was fed with air to protect the clutch solenoid valve and prevent damage that would affect the test.

[0022] Furthermore, during the test, the TCU determines whether the TB performance meets the design requirements based on the response time, braking slope, and exit time. This can meet the testing requirements of various tests such as TB braking and exit responsiveness, braking performance, and life testing.

[0023] Furthermore, the host computer communicates with the TCU via the UDS / XCP protocol (step S3), supports high-speed data transmission, and displays the test process data (such as speed and response time) in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a test flow chart of a commercial vehicle AMT brake performance and life test method of the present invention; Figure 2 This is a schematic diagram of a commercial vehicle AMT brake performance and life test system of the present invention; Figure 3 This is a schematic diagram of the human-computer data interaction principle in a commercial vehicle AMT brake performance and life test system of the present invention; Figure 4 This is the design principle diagram of an integrated medium truck AMT brake; Figure 5 This is a schematic diagram of the TB braking process of an integrated medium-duty truck AMT brake. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0026] The present invention discloses a method for testing the performance and life of an AMT brake of a commercial vehicle, comprising the following steps: Step 1: Install the AMT transmission on a test bench that meets the experimental conditions and connect it to the motor through a clutch. The test bench provides experimental conditions including: 24V DC power supply and 8±0.5bar compressed air, which fully simulates the vehicle environment. This ensures that the operating state of the TB during the test is consistent with the actual gear shifting, thereby ensuring the accuracy of the test results.

[0027] Step 2: Use MATLAB Simulink to build a test model and generate C code. Use integrated low-level software such as HighTec to integrate ASW and BSW and compile them to generate executable files such as .s19 or .hex. Flash them into the TCU to achieve automated testing. Figure 1 , the specific test steps are: S21, the host computer sends a command to the TCU to start the test; In S22, the TCU determines whether the experimental conditions are met. If so, it proceeds to S23. Otherwise, it waits for the experimental conditions to be met before proceeding to S21. The experimental conditions include: the air source pressure is maintained between 7 and 8.5 bar, the transmission is in neutral position, and the motor speed is maintained at 1800 ± 100 rpm. The parameters are selected to ensure that the TB test conditions and the vehicle usage environment are as consistent as possible.

[0028] S23, the TCU controls the clutch actuator to exhaust air, causing the clutch to engage; In S24, the TCU determines whether the speed of the first shaft of the transmission (that is, the input shaft) has reached the preset value. If so, it proceeds to S25. Otherwise, it proceeds to S23 to continue exhausting and engaging the clutch. If the exhaust time exceeds 10 seconds and the speed of the first shaft still does not meet the preset value, an error is reported, the clutch solenoid valve is closed, and the test exits. S25: Before air intake, the TCU controls the clutch solenoid valve to close for 3 seconds and then open it to prevent it from failing due to high temperature caused by continuous operation during high-frequency testing and to take into account the cycle of the entire test process. The TCU also controls the clutch actuator to intake air, pushing the clutch to disengage. In step S26, the TCU determines whether the clutch has reached the set disengagement position based on the received clutch displacement signal. If so, it proceeds to step S27; otherwise, it proceeds to step S25 to continue disengaging the clutch. If the clutch still has not reached the set disengagement position after the intake time exceeds 10 seconds, an error is reported, the clutch solenoid valve is closed, and the test is exited. S27, open the TB solenoid valve and set the preset value; S28, TCU determines whether the TB performance meets the design requirements. If so, the number of successes is increased by 1 and the next test is entered. Otherwise, the number of failures is increased by 1 and the next test is entered. When the cumulative number of successes reaches the design value, the life test passes.

[0029] Step 3: The host computer interacts with the TCU through UDS or XCP, sends different test commands, implements different test items, and sends data representing the test process and results through the CAN bus and displays them on the host computer interface.

[0030] The commercial vehicle AMT brake performance and life testing method disclosed in the present invention utilizes the three core advantages of environmental control, full-process automation, and real-time data interaction to achieve efficient, standardized, and intelligent AMT brake performance testing, significantly improving test efficiency (efficiency increased by approximately 60%), accuracy (error rate <0.5%), and reliability, while reducing R&D and maintenance costs, providing strong testing support for the rapid iteration of commercial vehicle AMT technology.

[0031] The present invention also discloses a commercial vehicle AMT brake performance and life test system, referring to Figure 2 、3 , including test bench, clutch, TCU, speed sensor, displacement sensor, compressed air control actuator, solenoid valve, and host computer. The test bench is controlled by the motor controller to provide torque and speed for the rear-end clutch; the clutch is installed between the AMT gearbox and the test bench, and the TCU controls the separation and engagement of the clutch to transmit the power of the motor to the gearbox input shaft; the speed sensor on the AMT gearbox is used to detect the speed of the gearbox input shaft, and the displacement sensor is used to detect the gear selection displacement and clutch displacement signal. The sensor transmits the signal to the TCU through the wiring harness; the TCU controls the solenoid valve through the wiring harness, thereby realizing the separation and engagement of the clutch and the braking of the TB through the compressed air control actuator; the TCU and the host computer are connected and communicated through the CAN line; the test bench provides the AMT gearbox with 8±0.5bar dry compressed air and a 24V DC power supply. The compressed air requires a gas tank with a volume of not less than 10L in front, and the inner diameter of the air supply pipe is not less than 11mm.

[0032] The host computer sends UDS commands or online calibration to the TCU via the CAN line and tools such as Kvaser / CANape. The TCU feeds back the execution results of the UDS commands to the host computer via the CAN line, and sends signals such as the input shaft speed, solenoid valve command, and the number of test completions during the test to the CAN bus. The host computer displays the relevant information.

[0033] Reference Figure 4 、 5 Taking an integrated medium-duty truck AMT brake as an example, during the test, the preset value of the input shaft speed is set to 1800±100rpm, and the preset value of the TB solenoid valve is 200ms. During the test, the TCU judges whether the TB performance meets the design requirements based on the response time (30~50ms), braking slope (2700~4000rpm / s), and exit time (40~60ms). The response time is the time from the TCU issuing the TB solenoid valve operation command to the input shaft speed changing from natural deceleration to braking deceleration, recorded as t0~t1; the braking slope is the speed change rate of a shaft speed during braking deceleration, t1~t2 is the direct change rate; the exit time is the time from the TCU issuing the TB solenoid valve closing command to the input shaft speed changing from braking deceleration to natural deceleration, recorded as t2~t3.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and replacements, and these modifications and replacements are also within the scope of protection covered by the claims.

Claims

1. A commercial vehicle AMT brake performance and life testing method, characterized in that: The following steps are involved: Step 1: Install the AMT gearbox on a test bench that meets the experimental conditions and connect it to the motor through a clutch; Step 2: Build the test model using MATLAB Simulink, generate C code, integrate the underlying software using HighTec, generate an executable file, and flash it to the TCU. Step 3: The host computer interacts with the TCU, and the data representing the test process and results are sent via the CAN bus and displayed on the host computer interface.

2. The commercial vehicle AMT brake performance and life testing method according to claim 1, characterized in that: In step 1, the test bench provides the following experimental conditions for the test: 24V DC power supply and 8±0.5bar compressed air.

3. The commercial vehicle AMT brake performance and life testing method according to claim 1, characterized in that: In step 2, the specific test steps in the executable file are: S21, the host computer sends a command to the TCU to start the test; In step S22, the TCU determines whether the experimental conditions are met. If so, it proceeds to step S23. Otherwise, it waits for the experimental conditions to be met before proceeding to step S21. S23, the TCU controls the clutch actuator to exhaust air, causing the clutch to engage; In step S24, the TCU determines whether the speed of the first gearbox shaft has reached the preset value. If so, it proceeds to step S25. Otherwise, it proceeds to step S23 to continue exhausting and engaging the clutch. If the exhaust time exceeds 10 seconds and the speed of the first gear shaft still does not meet the preset value, an error is reported, the clutch solenoid valve is closed, and the test is exited. S25, TCU controls the clutch actuator to intake air and push the clutch to disengage; In step S26, the TCU determines whether the clutch has reached the set disengagement position based on the received clutch displacement signal. If so, it proceeds to step S27; otherwise, it proceeds to step S25 to continue disengaging the clutch. If the clutch still has not reached the set disengagement position after the intake time exceeds 10 seconds, an error is reported, the clutch solenoid valve is closed, and the test is exited. S27, open the TB solenoid valve and set the preset value; S28, the TCU determines whether the TB performance meets the design requirements. If so, the success count is increased by 1 and the next test is started. Otherwise, the failure count is increased by 1 and the next test is started. When the cumulative number of successes reaches the designed value, the life test passes.

4. The commercial vehicle AMT brake performance and life testing method according to claim 3, characterized in that: In S22, the experimental conditions include: the air source pressure is maintained between 7 and 8.5 bar, the gearbox is in neutral position, and the motor speed is maintained at 1800 ± 100 rpm.

5. The commercial vehicle AMT brake performance and life testing method according to claim 3, characterized in that: In S24, the preset value is 1800±100 rpm.

6. The commercial vehicle AMT brake performance and life testing method according to claim 3, characterized in that: In S25, before intake, the TCU controls the clutch solenoid valve to close for 3 seconds and then open it.

7. The commercial vehicle AMT brake performance and life testing method according to claim 3, characterized in that: In S27 , the preset value is 200 ms.

8. The commercial vehicle AMT brake performance and life testing method according to claim 3, characterized in that: In S28, the TCU determines whether the TB performance meets the design requirements based on the response time, braking slope, and exit time. The response time is the time from the TCU issuing the command for the TB solenoid valve to work to the input shaft speed starting to change from natural deceleration to braking deceleration, recorded as t0~t1; the braking slope is the speed change rate of a shaft speed during braking deceleration, t1~t2 is the direct change rate; the exit time is the time from the TCU issuing the command for the TB solenoid valve to close to the input shaft speed changing from braking deceleration to natural deceleration, recorded as t2~t3.

9. The commercial vehicle AMT brake performance and life testing method according to claim 1, characterized in that: In step 3, the host computer interacts with the TCU through UDS or XCP.

10. A commercial vehicle AMT brake performance and life test system, characterized in that: It includes a test bench, clutch, TCU, speed sensor, displacement sensor, compressed air control actuator, solenoid valve, and host computer. The test bench is controlled by a motor controller to provide torque and speed for the rear-end clutch; the clutch is installed between the AMT gearbox and the test bench, and the TCU controls the separation and engagement of the clutch to transmit the power of the motor to the gearbox input shaft; the speed sensor on the AMT gearbox is used to detect the speed of the gearbox input shaft, and the displacement sensor is used to detect the gear selection displacement and clutch displacement signal, and the sensor transmits the signal to the TCU through the wiring harness; the TCU controls the solenoid valve through the wiring harness, thereby realizing the separation and engagement of the clutch and the braking of the TB through the compressed air control actuator; the TCU and the test bench host computer are connected and communicated through a CAN line; the test bench provides the AMT gearbox with 8±0.5bar dry compressed air and a 24V DC power supply. The compressed air requires a gas tank with a volume of not less than 10L in front, and the inner diameter of the air supply pipe is not less than 11mm.

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