Automated venting method, system, and vehicle for a hydraulic braking system

Abstract

The application discloses an automatic exhaust method and system of a hydraulic brake system and a vehicle, and relates to the technical field of intelligent chassis, and is applied to a whole vehicle production line repair station, and comprises the following steps: after preparation through hardware connection, a first diagnosis instruction is sent to an ECU by an upper computer to start an exhaust routine, the ECU checks an entry condition after receiving the instruction, if the entry condition is satisfied, the exhaust routine is set to a running state, meanwhile, the ECU performs phased automatic exhaust control, the on and off time of a motor and an electromagnetic valve is controlled, and different parts of the brake system are sequentially exhausted; the upper computer periodically sends a state query instruction to the ECU to obtain the running state of the exhaust routine; when it is found that the exhaust routine is executed, the upper computer sends a second diagnosis instruction to the ECU, obtains feedback pressure maintaining data and judges whether the exhaust is qualified, if the exhaust is qualified, the exhaust process is ended, otherwise, the exhaust routine is automatically returned to be re-executed. The application can realize automatic exhaust and improve the production efficiency of the whole vehicle.

Description

Technical Field

[0001] This invention relates to the field of intelligent chassis technology, and in particular to an automated exhaust method, system and vehicle for a hydraulic braking system. Background Technology

[0002] Currently, the mainstream mass-produced intelligent braking system on the market is a hydraulic brake-by-wire system. This system uses an electronic control unit (ECU) to regulate solenoid valves and motors to establish braking pressure, driving the braking components to decelerate and park the vehicle. After vehicle assembly, if the braking system has poor sealing, air intake issues in the lines or brakes, the braking performance will fail to meet standards and will not pass the end-of-life (EOL) test on the production line, requiring manual rework and bleed air. There are currently two main bleed air methods: First, one person presses the brake pedal while another person opens and closes the bleed bolt to bleed the air. This requires multiple people working together, is time-consuming, costly, and difficult to operate. Second, the solenoid valve is controlled by UDS diagnostic commands, and the pedal is pressed synchronously by a person. This requires a high degree of coordination; improper timing can lead to incomplete bleed air, requiring repeated work and affecting the production efficiency of the entire vehicle production line. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an automated exhaust method, system, and vehicle for hydraulic braking systems. By rationally designing an automated exhaust scheme that controls the electronic valve and motor, it solves the problems of low efficiency, the need for multiple operators, long exhaust time, difficulty in controlling the operating rhythm, and low exhaust pass rate in existing technologies, which affect the overall vehicle production efficiency.

[0004] In a first aspect, the present invention provides an automated venting method for a hydraulic braking system, applied to a rework station on a vehicle production line, comprising: Loosen the bleed screws on the wheel cylinders of the hydraulic braking system, connect them to the brake fluid reservoir via pipes, and connect the braking system ECU to the host computer. The host computer sends the first diagnostic command to the ECU to start the exhaust routine. After receiving the command, the ECU checks the entry conditions. If the entry conditions are met, the exhaust routine is set to the running state. At the same time, the ECU executes phased automated exhaust control. By controlling the power-on and power-off time of the motor and solenoid valve, exhaust is sequentially performed on different parts of the braking system. The host computer periodically sends status query commands to the ECU to obtain the running status of the exhaust routine. When the exhaust routine is found to be completed, the host computer sends a second diagnostic command to the ECU to obtain the feedback pressure holding data and determine whether the exhaust is qualified. If it is qualified, the exhaust process ends; otherwise, it automatically returns to re-execute the exhaust routine.

[0005] A further technical solution is that the first diagnostic instruction includes: The start routine sub-instruction is used to start the exhaust routine; The stop routine subinstruction is used to terminate the currently running exhaust routine; The query routine status sub-instruction is used to query the current status of the exhaust routine; The response data of the query routine status sub-instruction includes two bytes. The first byte reflects the current running status, which includes running status, completed status, and exit status. The second byte reflects the exit reason. The hydraulic braking system ECU checks the entry conditions, including: determining that the vehicle is stationary through the vehicle speed sensor signal; determining that the braking system actuator is fault-free through the fault diagnosis module; and determining that the system voltage is within the normal operating range through the voltage monitoring module. When all conditions are met, the ECU sets the exhaust routine status to running; when any condition is not met, the ECU returns a rejection response.

[0006] A further technical solution, phased exhaust control, includes four stages: The first stage involves purging the gas from the external hydraulic lines of the brake. In the second stage, the liquid outlet valve and the pressure boosting valve at the wheel cylinder end are circulated and vented. The third stage is to expel the gas from the master cylinder; In the fourth stage, residual gas is vented in a directional manner through the wheel cylinder bleed bolt.

[0007] In a further technical solution, the first stage uses a displacement loop control mode to drive the motor to push the brake fluid, control all outlet valves, pressure boosting valves and isolation valves to be energized, the motor rotates forward to push the piston forward to the displacement limit and then reverses to retract; repeats the preset number of cycles to discharge the gas in the external hydraulic pipeline of the brake.

[0008] A further technical solution involves using a torque loop control mode in the second stage to drive the motor to build pressure, controlling the two isolation valves to remain energized throughout the entire second stage, controlling the two booster valves to delay energization in each cycle, and controlling each outlet valve to be energized sequentially in each cycle according to a preset order. After the target pressure is established by the motor, the pressure difference is used to circulate and exhaust gas from the outlet valves and booster valves at the wheel cylinder end. The preset number of cycles is repeated to exhaust the gas from the upstream pipelines of each outlet valve and the wheel cylinder.

[0009] In a further technical solution, the third stage uses a displacement loop control mode to drive the motor to push the brake fluid, control all inlet valves and two booster valves to be energized simultaneously, and the brake fluid flows along the path of booster valve, isolation valve, master cylinder to reservoir. After the motor's forward stroke ends, all solenoid valves are de-energized and active pressure building is stopped. After waiting for a preset time to stabilize the pressure in the pipeline, the motor reverses to return and replenish the fluid. The preset number of cycles is repeated to expel the gas in the master cylinder.

[0010] A further technical solution involves using a torque loop control mode to drive the motor to build pressure in the fourth stage. This involves energizing the inlet valves corresponding to the left rear wheel, the left front wheel, and the right front wheel, while de-energizing the inlet valve corresponding to the right rear wheel. It also involves energizing the outlet valve corresponding to the right rear wheel and de-energizing the other three outlet valves. Furthermore, it involves energizing the first booster valve and de-energizing the second booster valve. A single hydraulic path is constructed through a specific wheel cylinder to the bleed bolt via a combination of solenoid valve states, allowing the brake fluid carrying residual gas to be discharged through the wheel cylinder bleed bolt.

[0011] A further technical solution is that the host computer periodically sends status query commands to the ECU, including: the host computer sends a query routine status sub-command to the ECU every 0.5s to 2s until feedback on the exhaust routine completion status is received.

[0012] A further technical solution involves the host computer sending a second diagnostic command to the ECU to obtain the feedback pressure holding data and determine whether the exhaust is qualified, including: The host computer sends a second diagnostic command to the ECU, controlling the ECU to build up pressure to a preset pressure and maintain pressure for a preset duration; the second diagnostic command is a pressure build-up and pressure maintenance verification command. The host computer obtains the pressure data during the pressure holding process through the pressure holding result query command, and judges the venting effect based on the pressure drop rate during the pressure holding period; if the pressure drop rate is lower than the preset threshold, the venting is deemed qualified and the venting process ends; if the pressure drop rate is higher than the preset threshold, the venting is deemed unqualified and the venting routine is automatically returned to be re-executed.

[0013] A further technical solution, when the exhaust is deemed unqualified, includes: supplementing the exhaust by manually pressing the brake pedal; after supplementing the exhaust, re-execute the pressure building and holding verification steps.

[0014] In a second aspect, the present invention provides an automated exhaust system for a hydraulic braking system, including a braking system ECU; the ECU has a built-in automated exhaust software submodule, the automated exhaust software submodule including a communication layer and an execution layer; The communication layer is used to receive diagnostic service routine instructions sent by the host computer, check the conditions that the exhaust routine needs to meet to enter the running state, including the vehicle stationary state, the actuator fault state, and the system voltage normal state, manage the running state and exit reasons of the exhaust routine, and feed back the current status information to the host computer. The execution layer is used to execute the automated venting method of the hydraulic braking system described above.

[0015] Thirdly, the present invention also provides a vehicle comprising an automated exhaust system of the aforementioned hydraulic braking system, or an automated exhaust method for performing the aforementioned hydraulic braking system.

[0016] Fourthly, the present invention also provides an electronic device, comprising: a memory for storing executable instructions; and a processor for implementing the above-described automated exhaust method for a hydraulic braking system when executing the executable instructions stored in the memory.

[0017] Fifthly, the present invention also provides a computer-readable storage medium storing executable instructions for causing a processor to execute the executable instructions to implement the above-described automated venting method for the hydraulic braking system.

[0018] The above one or more technical solutions have the following beneficial effects: This invention provides an automated venting method, system, and vehicle for a hydraulic braking system. By embedding an automated venting software submodule in the ECU, the host computer only needs to send a UDS diagnostic command to start the venting routine. The ECU can automatically execute a four-stage layered venting control strategy, eliminating the need for repeated pedal pressing or precise control of the operating rhythm. This achieves full automation of the venting process, requiring only one operator, significantly reducing labor costs. Through the four-stage layered venting control strategy, different parts such as the external hydraulic lines of the brake, the wheel cylinder outlet valve and booster valve, the master cylinder, and the wheel cylinder bleed bolt passage are targeted with alternating displacement and torque loop control modes, combined with precise solenoid valve on / off combinations, achieving comprehensive venting of all corners of the braking system and overcoming the shortcomings of incomplete venting in existing technologies. In addition, through a closed-loop control mechanism of venting-verification-judgment-retry, pressure building and holding verification is automatically performed after venting is completed. The venting effect is objectively judged based on the pressure drop rate during the holding period. If it is unqualified, the venting routine is automatically returned to be re-executed, ensuring that the venting qualification rate reaches over 95% and avoiding the subjectivity and inconsistency of manual judgment. The solution proposed in this invention can reduce the exhaust time from several minutes to less than 60 seconds, greatly improving the exhaust efficiency of the rework station and significantly enhancing the production efficiency of the vehicle production line.

[0019] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a torque-pressure-time curve for the presence of gas in the braking system. Figure 2 A schematic diagram of the hardware architecture of an existing wire-controlled hydraulic braking system; Figure 3 This is a flowchart of the automated air venting method for the hydraulic braking system proposed in this embodiment of the invention; Figure 4 This is a schematic diagram of the staged exhaust control logic in an embodiment of the present invention; Figure 5 This is a flowchart of the rework verification process in an embodiment of the present invention; Figure 6 This is a torque-pressure time curve of the braking system after exhaust treatment in an embodiment of the present invention. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are exemplary and are intended only to describe specific embodiments and to provide further explanation of the invention, and are not intended to limit the scope of exemplary embodiments of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Terminology Explanation Displacement loop control mode: This mode refers to the precise control of the motor's stroke and speed to propel the brake fluid. The motor moves according to preset displacement and speed parameters, which is suitable for the venting stage where stable propulsion of brake fluid is required.

[0024] Torque loop control mode: This refers to establishing system pressure by precisely controlling the output torque of the motor. The motor outputs torque according to preset parameters and is suitable for the exhaust stage where a target pressure needs to be established.

[0025] UDS Diagnostic Service Routine: Refers to the diagnostic function based on the Unified Diagnostic Services protocol. The host computer communicates with the ECU through specific diagnostic commands to trigger and monitor the execution of exhaust routines.

[0026] Inlet valve (EV): A solenoid valve used to control the flow of brake fluid from the booster cylinder to the wheel cylinder. It opens the hydraulic passage when powered on and closes the hydraulic passage when powered off.

[0027] Outlet valve (AV): A solenoid valve used to control the flow of brake fluid from the wheel cylinder to the reservoir. It opens the hydraulic passage when powered on and closes the hydraulic passage when powered off.

[0028] Power booster valve (PSV): A solenoid valve used to control the flow of brake fluid from the booster cylinder to the master cylinder. It opens the hydraulic passage when powered on and closes the hydraulic passage when powered off.

[0029] Isolation valve (CSV): A solenoid valve used to control the hydraulic connection between the booster cylinder and the master cylinder. It opens the hydraulic passage when powered on and closes the hydraulic passage when powered off.

[0030] The design concept of the proposed solution in this invention is as follows: As noted in the background section, in existing braking systems employing hydraulic brake-by-wire mechanisms, the electronic control unit (ECU) comprehensively controls the on / off states of various hydraulic solenoid valves and the precise pressure-building capability of the motor. This controls the flow direction and velocity of brake fluid in the braking system lines or motor housing, generating braking pressure to push the brake pads and discs into contact, producing braking force to decelerate or stop the vehicle. However, during the verification of the braking system on the automated production line after assembly in the vehicle manufacturing workshop, issues such as air leaks or sealing problems, or the potential presence of gas inside the brake or in the brake lines, can lead to a decrease in braking performance. Figure 1 The test demonstrated the performance defects of the braking system when gas is present. The curve showed that the braking torque drops rapidly after reaching its peak, which also intuitively illustrates the problem of unstable braking performance caused by gas. The system could not pass the EOL production line test and needed to be sent to the rework station for manual gas evacuation.

[0031] Currently, the common venting methods used in rework stations mainly include two types: The first method relies entirely on manual pedal operation for venting, requiring two employees to work together, one to operate the pedal and the other to open and close the vent bolt. This venting process is time-consuming and results in high venting costs. The second method uses UDS diagnostic commands to control the opening and closing of a solenoid valve, while also requiring manual operation to vent the gas according to the rhythm of the switch. The rhythm of the commands from the host computer and the rhythm of pedal operation need to be perfectly coordinated. For ordinary operators, this is quite complex and requires mastering the venting rhythm. Otherwise, the gas inside the casing may not be able to escape, resulting in unqualified venting and requiring repeated manual venting operations, which is time-consuming and labor-intensive.

[0032] In summary, the existing hydraulic brake system venting method at the vehicle production line rework station has drawbacks such as requiring multiple operators, long venting time, difficulty in controlling the operating rhythm, low venting pass rate, and the need for repeated operations. These drawbacks result in low venting efficiency at the rework station, affecting the production efficiency of the vehicle production line.

[0033] To address the aforementioned technical problems, this invention provides an automated venting method, system, and vehicle for a hydraulic braking system. The overall technical implementation is as follows: the venting process is triggered by a UDS diagnostic service routine. The ECU's built-in automated venting software submodule automatically executes a four-stage hierarchical differentiated venting control strategy. For different parts of the braking system, displacement loop control mode and torque loop control mode are used alternately for control. With precise solenoid valve on / off combination timing, comprehensive venting is achieved for various parts such as the external hydraulic pipelines of the brake, wheel cylinder end valves, master cylinder, and bleed bolt passage. After venting is completed, the venting effect is quantitatively judged through a pressure building and holding verification mechanism. If it fails, it is automatically retried, forming a complete "venting-verification-judgment-retry" closed-loop control mechanism.

[0034] The application scenario of this invention is the rework station on a vehicle production line. After assembly in the vehicle manufacturing workshop, during the verification of the braking system on the automated production line, leakage or sealing issues, or the possible presence of gas inside the brake or brake lines, can lead to decreased braking performance and failure to pass the EOL (End-of-Life) production line test. In such cases, the system needs to be moved to the rework station for bleed air. At the rework station, the operator opens the bleed screws on each wheel cylinder, connects a hose to the brake fluid reservoir, connects the diagnostic equipment to the vehicle's OBD diagnostic interface, and initiates the automated bleed air process by sending a UDS (Unified Diagnostic Service) command to the host computer.

[0035] Example 1 This embodiment provides an automated venting method for a hydraulic braking system, applied to the rework station of a vehicle production line. By rationally designing an automated venting scheme that controls the electronic valve and motor, it solves the problems of low efficiency, the need for multiple operators, long venting time, difficulty in controlling the operating rhythm, and low venting pass rate in the existing technology, which affect the overall vehicle production efficiency.

[0036] As one implementation method, the hardware architecture of the hydraulic braking system applicable to this embodiment is as follows: Figure 2As shown, the hydraulic braking system includes a motor (including a motor-driven piston pump PSU), a master cylinder, four wheel cylinders, a solenoid valve assembly, a pressure sensor, and an electronic control unit (ECU). The motor drives a piston to move within the booster cylinder, and the reciprocating motion of the piston propels brake fluid through the hydraulic lines. The master cylinder is hydraulically connected to a reservoir via pipelines, which stores brake fluid. The four wheel cylinders are designated as the left front wheel cylinder (FL), right front wheel cylinder (FR), left rear wheel cylinder (RL), and right rear wheel cylinder (RR), each corresponding to the brake of one wheel. The solenoid valve assembly includes four inlet valves (E... The system includes four outlet valves (AV_FL, AV_FR, AV_RL, AV_RR), two booster valves (PSV1, PSV2), and two isolation valves (CSV1, CSV2). Additionally, pressure sensors are used to detect pressure within the braking system lines, including the master cylinder pressure sensor (MPS) and the booster cylinder pressure sensor (HPS_PSU). The ECU controls the motor's motion mode and parameters via control signals, as well as the energization / de-energization status of each solenoid valve in the solenoid valve assembly.

[0037] As one implementation method, the hydraulic connection relationship between the components is as follows: 1) The input ends of the inlet valves are hydraulically connected to the output ends of the booster cylinder, and the output ends are hydraulically connected to the four wheel cylinders. Specifically, the output end of the inlet valve EV_FL is hydraulically connected to the left front wheel cylinder FL, the output end of the inlet valve EV_FR is hydraulically connected to the right front wheel cylinder FR, the output end of the inlet valve EV_RL is hydraulically connected to the left rear wheel cylinder RL, and the output end of the inlet valve EV_RR is hydraulically connected to the right rear wheel cylinder RR.

[0038] 2) The booster cylinder body is hydraulically connected to two isolation valves via two booster valves, and the two isolation valves are hydraulically connected to the main cylinder. Specifically, the booster cylinder body is hydraulically connected to isolation valve CSV1 via booster valve PSV1, and isolation valve CSV1 is hydraulically connected to the first chamber of the main cylinder; the booster cylinder body is hydraulically connected to isolation valve CSV2 via booster valve PSV2, and isolation valve CSV2 is hydraulically connected to the second chamber of the main cylinder.

[0039] 3) The input ends of the discharge valves are hydraulically connected to the four wheel cylinders respectively, and the output ends are hydraulically connected to the reservoir. Specifically, the input end of the discharge valve AV_FL is hydraulically connected to the left front wheel cylinder FL, the input end of the discharge valve AV_FR is hydraulically connected to the right front wheel cylinder FR, the input end of the discharge valve AV_RL is hydraulically connected to the left rear wheel cylinder RL, and the input end of the discharge valve AV_RR is hydraulically connected to the right rear wheel cylinder RR. The output ends of all the discharge valves converge and are hydraulically connected to the reservoir.

[0040] The aforementioned hardware architecture provides the foundation for phased differentiated exhaust control. Through reasonable hydraulic connections and solenoid valve layout, the ECU can precisely control the flow of brake fluid in different pipelines, thereby achieving targeted exhaust for different parts.

[0041] Based on the aforementioned hydraulic brake system, this embodiment provides a corresponding automated air release method, such as... Figure 3 As shown, it includes the following steps: Step S1: Hardware Connection Preparation. At the repair station, the operator opens the bleed screws on each wheel cylinder of the hydraulic braking system, connects the bleed screws to the brake fluid reservoir via hoses, and connects the diagnostic equipment to the vehicle's OBD diagnostic interface, thus establishing a communication connection between the host computer and the braking system ECU.

[0042] In some embodiments, the four wheel cylinders are the left front wheel cylinder, the right front wheel cylinder, the left rear wheel cylinder, and the right rear wheel cylinder. The bleed bolt of each wheel cylinder needs to be opened and connected to the brake fluid reservoir through a hose so that gas and brake fluid can be smoothly discharged during the bleed process.

[0043] Step S2: UDS Diagnostic Command Trigger and Entry Condition Check. The host computer (such as a Tester diagnostic tool) sends the first diagnostic command to the ECU to start the exhaust routine. After receiving the command, the ECU checks the entry conditions. If the entry conditions are met, the exhaust routine is set to running state.

[0044] Specifically, the first diagnostic instruction is the UDS diagnostic service routine instruction 3101ACF0 specially designed in this embodiment, which includes three sub-instructions: (1) Start Routine sub-instruction 3101ACF0(0x01 Start Routine) is used to start the exhaust routine; (2) The stop routine sub-instruction 3102ACF0(0x02 Stop Routine) is used to terminate the running exhaust routine; (3) The query routine status sub-instruction 3103ACF0(0x03 Request Routine Result) is used to query the current status of the exhaust routine.

[0045] The response data for the query routine status sub-instruction includes two bytes. The first byte provides feedback on the current running status, which includes running, complete, and exit status. The second byte provides feedback on the reason for exiting.

[0046] Furthermore, the conditions for entering an ECU check include: (1) Determine whether the vehicle is stationary by using the vehicle speed sensor signal; (2) The fault diagnosis module determines that the brake system actuator is fault-free; (3) The voltage monitoring module determines that the system voltage is within the normal operating range.

[0047] When all conditions are met, the ECU sets the exhaust routine status to running; when any condition is not met, the ECU returns a rejection response and feeds back the specific reason for exit in the second byte of the response data.

[0048] like Figure 5 As shown, after receiving request 3101ACF0 from the host computer, the exhaust routine state machine inside the ECU first performs a condition check. If the EOL Routine condition is met, it enters the Running Status and begins to execute the solenoid valve and motor control according to the preset timing. If a fault or misoperation occurs during execution, or if a stop request 3102ACF0 is received, the reason for the Routine interruption is recorded and stored and the program exits.

[0049] In step S2, after determining that the EOL Routine condition is met and entering Running Status, the ECU automatically executes phased automated exhaust control, sequentially exhausting different parts of the braking system by controlling the power-on and power-off times of the motor and solenoid valve. For example... Figure 4 As shown, the phased control proposed in this embodiment includes four stages, and the timing sequence of the four-stage layered exhaust control is as follows: The first stage involves purging the gas from the external hydraulic lines of the brake.

[0050] Specifically, in the first stage, a displacement loop control mode is used to drive the motor to actuate the brake fluid. The ECU controls all outlet valves (AV_FL, AV_FR, AV_RL, AV_RR), two booster valves (PSV1, PSV2), and two isolation valves (CSV1, CSV2) to be energized simultaneously, opening the hydraulic passage from the booster cylinder through the wheel cylinder to the reservoir. In displacement loop control mode, the motor is set to a movement speed of 15mm / s to 25mm / s, preferably 20mm / s, and a displacement limit of 40mm to 50mm, preferably 44.5mm. After the motor rotates forward, pushing the piston to the displacement limit, it reverses and retracts 0.3mm to 1mm, preferably 0.5mm.

[0051] The above actions are repeated a preset number of cycles, preferably 3 times, to expel the gas from the external hydraulic lines of the brake.

[0052] The first stage primarily targets the external hydraulic lines of the brake, most of which are located outside the brake assembly. A displacement loop control mode ensures stable propulsion of the brake fluid, guaranteeing the complete removal of air from the external lines. This stage utilizes displacement loop control to drive a high-flow-rate circulation of the brake fluid, forcibly removing accumulated air bubbles from the lines. This method is suitable for rapid degassing in long, large-diameter areas.

[0053] The second stage involves circulating and venting the liquid outlet valve and the booster valve at the cylinder end.

[0054] Specifically, in the second stage, a torque loop control mode is used to drive the motor to build pressure. The ECU controls the two isolation valves (CSV1, CSV2) to remain energized throughout the entire second stage. The ECU controls the two booster valves (PSV1, PSV2) to delay energizing in each cycle; that is, they are not energized at the beginning of each cycle, but are energized after the motor has built up a certain pressure. The ECU controls the outlet valves to be energized sequentially in each cycle according to a preset order, preferably as follows: left rear wheel cylinder outlet valve (AV_LR) → left front wheel cylinder outlet valve (AV_LF) → right front wheel cylinder outlet valve (AV_RF) → right rear wheel cylinder outlet valve (AV_RR). In torque loop control mode, the motor's output torque is set to 0.3 Nm to 0.8 Nm, preferably 0.5 Nm. After the motor builds up the target pressure, the pressure difference is used to discharge the gas from the outlet valves at the wheel cylinder end, the upstream pipelines of the booster valves, and the inside of the wheel cylinder.

[0055] The above actions are repeated a preset number of times, preferably 3 times.

[0056] The second stage primarily involves circulating venting of gas from the outlet valves and booster valves at the wheel cylinder end. Pressure is established using a torque loop control mode. After establishing a base pressure, the pressure difference is used to vent gas from the upstream pipelines of each outlet valve and within the wheel cylinder. The delayed power-on design of the booster valve ensures the stability of pressure establishment, while the sequential power-on of each outlet valve enables separate venting from each wheel cylinder end, preventing gas residue in any particular pipeline.

[0057] Third stage: Expel the gas from the master cylinder.

[0058] Specifically, in the third stage, a displacement loop control mode is used to drive the motor to push the brake fluid. The ECU controls all inlet valves (EV_FL, EV_FR, EV_RL, EV_RR) and two booster valves (PSV1, PSV2) to be energized simultaneously. The brake fluid flows along the path of the booster valve, the isolation valve, the master cylinder, and the reservoir. In displacement loop control mode, the motor's movement speed is set to 15mm / s to 25mm / s, preferably 20mm / s, and the displacement limit is set to 40mm to 50mm, preferably 44.5mm. After the motor's forward stroke ends, the ECU de-energizes all solenoid valves and stops actively building pressure, waiting for a preset time for the pressure in the pipeline to stabilize, preferably 1s to 3s, more preferably 2s. Subsequently, the motor reverses to return and replenish the brake fluid.

[0059] The above actions are repeated a preset number of cycles, preferably 5 times, to expel the gas from the main cylinder.

[0060] The third stage focuses on venting the master cylinder, a critical component. Through a cycle of power-off voltage stabilization and repeated fluid replenishment by the motor, the gas inside the master cylinder is ensured to be fully expelled. The preset waiting time design ensures that the pressure within the pipeline is sufficiently stable, preventing incomplete venting due to pressure fluctuations.

[0061] Fourth stage: Residual gas is vented in a directional manner through the wheel cylinder bleed bolt.

[0062] Specifically, in the fourth stage, a torque loop control mode is used to drive the motor to build pressure. The ECU energizes the inlet valves (EV_LR) corresponding to the left rear wheel, the left front wheel, and the right front wheel, while de-energizing the inlet valve (EV_RR) corresponding to the right rear wheel. The ECU energizes the outlet valve (AV_RR) corresponding to the right rear wheel, while de-energizing the other three outlet valves (AV_FL, AV_FR, AV_RL). The ECU energizes the first boost valve (PSV1) and de-energizes the second boost valve (PSV2). In torque loop control mode, the motor's output torque is set to 0.3 Nm to 0.8 Nm, preferably 0.5 Nm. Through the above solenoid valve state combination, a single hydraulic path is constructed from the boost cylinder through a specific wheel cylinder to the bleed bolt, allowing the brake fluid carrying residual gas to be discharged through the wheel cylinder bleed bolt. The above actions are executed a preset number of cycles, preferably once.

[0063] The fourth stage utilizes precise solenoid valve on / off combinations to construct a single hydraulic path, enabling the directional discharge of residual gas. This design prevents gas from dispersing in other pipelines, ensuring the targeted and effective venting.

[0064] In one implementation method, the aforementioned control strategy is implemented through software coding. This software consists of two parts: one part interacts with the diagnostic host computer, receiving instructions from the host computer and checking whether the Rework Filling routine meets the conditions for entering the running state; the other part mainly controls the energization and de-energization of the solenoid valves and the displacement and speed of the motor according to the control timing of the solenoid valves and motors, thereby achieving the target pressure build-up capability and completing the automated exhaust action. Based on this, according to the software design scheme, the ECU UDS service and the host computer are coded separately, as is the control timing of the motor and solenoid valves. These two parts of code are then integrated into the entire ECU, and the hydraulic brake ECU or the vehicle release file is then flashed.

[0065] Step S4: Periodic Status Query. The host computer periodically sends status query commands to the ECU to obtain the running status of the exhaust routine.

[0066] Specifically, the host computer sends a query routine status sub-command (3103ACF0) to the ECU every 0.5s to 2s, preferably at an interval of 1s, until feedback on the exhaust routine completion status is received.

[0067] like Figure 1 As shown, after initiating the 3101ACF0 exhaust service, the host computer enters a periodic query state, obtaining the current status of the exhaust routine through the 3103ACF0 service until the rework filling is completed. This periodic status query mechanism ensures that the host computer can monitor the execution progress of the exhaust routine in real time, promptly detect anomalies, and take appropriate measures. The query interval setting balances real-time performance and communication efficiency, avoiding frequent communication that consumes ECU resources.

[0068] Step S5: Perform pressure build-up and pressure holding verification and pass / fail judgment. That is, when the exhaust routine is found to be completed, the host computer sends a second diagnostic command to the ECU, obtains the feedback pressure holding data and judges whether the exhaust is qualified. If it is qualified, the exhaust process ends; otherwise, it automatically returns to re-execute the exhaust routine.

[0069] Specifically, the host computer sends a second diagnostic command to the ECU, controlling the ECU to build up pressure to a preset pressure and maintain that pressure for a preset duration. The second diagnostic command is the pressure build-up and pressure maintenance verification command (3101ACF1). The host computer obtains pressure data during the pressure maintenance process through the pressure maintenance result query command (3103ACF1), and judges the exhaust effect based on the pressure drop rate during the pressure maintenance period. If the pressure drop rate is lower than the first preset threshold, the exhaust is deemed qualified and the exhaust process ends. If the pressure drop rate is higher than the second preset threshold, the exhaust is determined to be unqualified, and the host computer will automatically return to re-execute the exhaust routine, that is, return to step S2 to resend the first diagnostic command to start the exhaust routine.

[0070] Figure 1 The pressure-time curve for a non-compliant exhaust system is shown. The pressure drops rapidly during the pressure holding period, indicating that there is still gas in the braking system. Figure 6 The pressure-time curve for holding pressure when the exhaust is qualified is shown. The pressure curve circled in red is relatively stable during the holding period, indicating that the exhaust effect is good.

[0071] In some embodiments, when exhaust gas is determined to be substandard, supplementary exhaust gas can be performed by manually pressing the brake pedal. After supplementary exhaust gas is completed, the pressure building and holding verification step is re-executed, i.e., step S5 is re-executed. Manual supplementary exhaust gas, as a supplement to automated exhaust gas, can handle the very few cases that automated exhaust gas cannot completely resolve, further improving the exhaust gas pass rate.

[0072] The pressure build-up and pressure holding verification mechanism described above objectively judges the exhaust effect through quantified pressure data, avoiding the subjectivity and inconsistency of human experience judgment. The automatic retry mechanism ensures the exhaust pass rate and reduces the need for manual intervention.

[0073] Through the above steps S1 to S5, the hydraulic braking system is automatically vented. The entire venting process requires only one person to operate, the venting time is within 60 seconds, and the venting qualification rate reaches more than 95%, which greatly improves the venting efficiency of the rework station and significantly improves the production efficiency of the vehicle production line.

[0074] In summary, this embodiment establishes a UDS diagnostic communication mechanism between the host computer and the braking system ECU, and integrates a four-stage hierarchical automated exhaust control strategy within the ECU. This enables fully automated, standardized, and closed-loop braking system exhaust operations at the rework station of the vehicle production line, fundamentally solving the pain points of traditional manual exhaust such as low efficiency, complex operation, poor consistency, and low pass rate. It significantly improves the vehicle manufacturing cycle time and braking system assembly quality, possessing outstanding engineering application value and mass production benefits, specifically reflected in: This solution significantly simplifies the operation process and reduces labor costs. Traditional exhaust systems require two people to operate the bleed valve and operate the bleed bolt simultaneously, or require precise manual synchronization of pedal operation and host computer commands, resulting in high operational barriers and labor intensity. This solution requires only one operator to complete the bleed bolt connection and diagnostic equipment access, enabling one-button start of fully automatic exhaust. The entire process requires no braking pedal operation or manual control of the solenoid valve rhythm, greatly reducing the skill requirements for operators, enabling single-person multi-station operation, reducing manpower input at rework stations by more than 50%, and effectively reducing overall vehicle manufacturing costs.

[0075] This solution fully automates the exhaust process, significantly reducing operation time. The ECU automatically controls the motor's forward and reverse rotation, the solenoid valve's on / off combination, and pressure holding determination according to a preset sequence, requiring no manual intervention or rhythm coordination, ensuring a continuous and stable exhaust process. Compared to traditional manual exhaust methods that can take several minutes, this solution can stably control the exhaust time of a single vehicle to within 60 seconds, improving work efficiency by over 70%. This directly alleviates the bottleneck at the EOL (End-of-Life) repair station, effectively supports continuous production on high-paced vehicle production lines, and avoids the risk of production line downtime due to exhaust delays.

[0076] This solution employs a four-stage, layered venting strategy, resulting in more thorough and residue-free venting. By sequentially venting external pipelines, wheel cylinder valve assemblies, master cylinder, and residual gas pathways in designated areas, combined with alternating displacement loop and torque loop control, it covers all areas of the hydraulic circuit prone to gas accumulation, preventing gas residue in valve chambers, dead zones of the master cylinder, and wheel cylinder pipelines. Compared to manual venting based on experience, this solution is more effective at removing tiny air bubbles and hidden air blockages, resulting in faster pressure build-up and more stable pressure holding in the braking system, thus improving the assembly quality of the braking system from the source.

[0077] This solution establishes a closed-loop verification mechanism, significantly improving the first-pass yield. After bleed test, a pressure build-up and holding test is automatically performed. The pressure drop rate objectively determines the bleed effect, replacing the subjective method of manual judgment based on pedal feel. The judgment criteria are unified, the results are quantifiable, and the data is traceable. If the test fails, the bleed test routine is automatically restarted, forming a closed loop of "bleed-detection-judgment-retry," ensuring a stable first-pass yield of over 95%. This significantly reduces repeated rework and testing, minimizing brake fluid waste and workstation wear.

[0078] This solution requires no hardware modifications, resulting in low production line upgrade costs and strong compatibility. The control solution achieves functionality solely through ECU software upgrades and optimized host computer diagnostic processes, eliminating the need for additional sensors, actuators, and wiring harnesses. It can be directly adapted to existing One-Box / Two-Box hydraulic drive-by-wire systems, compatible with mainstream passenger car and light commercial vehicle platforms, minimizing modification risk and rapid deployment, facilitating quick implementation by OEMs. This solution also enhances process controllability and data traceability. The entire process is collaboratively controlled by the ECU and host computer, ensuring precise timing and consistent parameters, avoiding quality variations caused by human error. Simultaneously, it records exhaust status, pressure holding data, and retry counts, facilitating data upload and quality traceability through integration with MES systems, meeting the stringent production management and quality system requirements of the automotive industry.

[0079] In summary, this embodiment has significant advantages in cost reduction, efficiency improvement, quality improvement, manpower reduction, and stable production cycle. It can comprehensively improve the assembly quality of hydraulic braking systems and lay the foundation for efficient, reliable, and scalable mass production of intelligent chassis.

[0080] Example 2 This embodiment provides an automated exhaust control system for a hydraulic braking system. The system includes a braking system ECU, with a built-in automated exhaust software submodule. This submodule includes a communication layer and an execution layer, wherein: 1) Communication layer, used to receive diagnostic service routine instructions sent by the host computer through the diagnostic equipment, check the conditions required for the exhaust routine to enter the running state, including vehicle stationary state, no actuator fault state and normal system voltage state, manage the running state and exit reason of the exhaust routine, and feed back the current status information to the host computer.

[0081] Specifically, the communication layer is responsible for parsing the UDS diagnostic commands sent by the host computer, including the 3101ACF0 command to start the exhaust routine, the 3102ACF0 command to stop the exhaust routine, and the 3103ACF0 command to query the exhaust routine status.

[0082] After receiving the exhaust start routine command, the communication layer checks whether the vehicle is stationary (judged by the vehicle speed sensor signal), whether the brake system actuators are fault-free (judged by the fault diagnosis module), and whether the system voltage is within the normal operating range (judged by the voltage monitoring module).

[0083] When all conditions are met, the communication layer sets the exhaust routine status to running and triggers the execution layer to start executing exhaust control; when any condition is not met, the communication layer returns a rejection response and records the specific exit reason.

[0084] As one implementation, the communication layer is also responsible for reporting the current status of the exhaust routine to the host computer. The response data includes two bytes: the first byte reports the running status (running / completed / exited), and the second byte reports the reason for exiting.

[0085] 2) Execution layer, used to execute the automated venting method of the hydraulic braking system described in Example 1.

[0086] Specifically, the execution layer controls the power-on and power-off states of each solenoid valve in the solenoid valve group, as well as the motion mode (displacement loop control mode or torque loop control mode) and motion parameters (speed, displacement, torque) of the motor according to the preset four-stage exhaust control sequence.

[0087] In the first stage, the actuator controls all outlet valves, booster valves, and isolation valves to be energized. The motor uses a displacement loop control mode to push the brake fluid to expel gas from the external hydraulic lines. In the second stage, the actuator controls the isolation valve to be energized throughout the entire stroke, the booster valve to be energized with a delay, and each outlet valve to be energized in turn. The motor uses a torque loop control mode to establish pressure and circulate exhaust gas at the wheel cylinder end. In the third stage, the actuator controls all inlet valves and booster valves to be energized. The motor uses a displacement loop control mode to push the brake fluid to expel gas from the master cylinder. After the motor's forward stroke ends, it de-energizes all solenoid valves, stabilizes the pressure, and then reverses to replenish the fluid. In the fourth stage, the actuator constructs a single hydraulic path through precise solenoid valve on / off combinations. The motor uses a torque loop control mode to establish pressure and directionally expel residual gas.

[0088] After completing the four-stage exhaust control, the execution layer notifies the communication layer to set the exhaust routine status to complete.

[0089] By embedding the exhaust control logic into the ECU software, autonomous execution of the exhaust process is achieved without relying on complex external control systems.

[0090] Example 3 This embodiment provides a vehicle that includes the automated exhaust control system for the hydraulic braking system described in Embodiment 3, or executes the automated exhaust method for the hydraulic braking system described in Embodiment 1. This vehicle can quickly and efficiently complete the exhaust of the braking system at the rework station on the vehicle production line, improving production efficiency.

[0091] Specifically, the vehicle is equipped with the hydraulic braking system described in Embodiment 2, and the ECU of this hydraulic braking system has a built-in automated bleed software submodule described in Embodiment 3. At the rework station on the vehicle production line, the operator connects the host computer to the vehicle's OBD diagnostic interface through diagnostic equipment, opens the bleed bolts of each wheel cylinder and connects them to the brake fluid reservoir through hoses. The host computer sends a UDS diagnostic command to start the automated bleed process. The bleed time is within 60 seconds, and the bleed pass rate reaches over 95%.

[0092] Example 4 This embodiment provides an electronic device, including: a memory for storing executable instructions; and a processor for executing the executable instructions stored in the memory to implement the automated air exhaust method of the hydraulic braking system provided in this embodiment.

[0093] This electronic device can be used as a host computer to control and monitor the exhaust process by communicating with the braking system ECU.

[0094] Specifically, the electronic device can be an industrial computer, a laptop computer, a tablet computer, or other electronic devices with computing and communication capabilities.

[0095] The electronic device connects to the vehicle's OBD diagnostic interface via a diagnostic device and runs dedicated diagnostic software. This diagnostic software implements the host computer control logic of the automated exhaust method described in Example 1, including functions such as sending UDS diagnostic commands, periodically querying the exhaust routine status, acquiring pressure holding data and determining the exhaust compliance, and automatically retrying when it fails.

[0096] Example 5 This embodiment also provides a computer-readable storage medium storing executable instructions, which, when executed by a processor, will cause the processor to execute the automated venting method of the hydraulic braking system provided in this embodiment.

[0097] This storage medium can be used to deploy exhaust control software on different electronic devices, improving the portability and flexibility of the solution.

[0098] Specifically, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a disk, or an optical disk, etc.

[0099] When the executable instructions stored in the storage medium are executed by the processor, they implement the host computer control logic of the automated exhaust method described in Embodiment 1, enabling any electronic device with computing and communication capabilities to be used as a host computer. By communicating with the braking system ECU, the exhaust process can be controlled and monitored. The steps and methods involved in Embodiments 2 to 5 above correspond to those in Embodiment 1. For specific implementation details, please refer to the relevant description section of Embodiment 1. The term "computer-readable storage medium" should be understood as a single medium or multiple media including one or more instruction sets; it should also be understood as including any medium capable of storing, encoding, or carrying an instruction set for execution by a processor and enabling the processor to perform any of the methods in this invention.

[0100] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0101] The above description is only a preferred embodiment of the present invention. Although the specific implementation of the present invention has been described in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. An automated air venting method for a hydraulic braking system, characterized in that, Applied to rework stations on vehicle production lines, including: Loosen the bleed screws on the wheel cylinders of the hydraulic braking system, connect them to the brake fluid reservoir via pipes, and connect the braking system ECU to the host computer. The host computer sends the first diagnostic command to the ECU to start the exhaust routine. After receiving the command, the ECU checks the entry conditions. If the entry conditions are met, the exhaust routine is set to the running state. At the same time, the ECU executes phased automated exhaust control. By controlling the power-on and power-off time of the motor and solenoid valve, exhaust is sequentially performed on different parts of the braking system. The host computer periodically sends status query commands to the ECU to obtain the running status of the exhaust routine. When the exhaust routine is found to be completed, the host computer sends a second diagnostic command to the ECU to obtain the feedback pressure holding data and determine whether the exhaust is qualified. If it is qualified, the exhaust process ends; otherwise, it automatically returns to re-execute the exhaust routine.

2. The automated air venting method for a hydraulic braking system as described in claim 1, characterized in that, The first diagnostic instruction includes: The start routine sub-instruction is used to start the exhaust routine; The stop routine subinstruction is used to terminate the currently running exhaust routine; The query routine status sub-instruction is used to query the current status of the exhaust routine; The response data of the query routine status sub-instruction includes two bytes. The first byte reflects the current running status, which includes running status, completed status, and exit status. The second byte reflects the exit reason. The hydraulic braking system ECU checks the entry conditions, including: determining that the vehicle is stationary through the vehicle speed sensor signal; determining that the braking system actuator is fault-free through the fault diagnosis module; and determining that the system voltage is within the normal operating range through the voltage monitoring module. When all conditions are met, the ECU sets the exhaust routine status to running; when any condition is not met, the ECU returns a rejection response.

3. The automated air venting method for a hydraulic braking system as described in claim 1, characterized in that, Phased exhaust control includes four phases: The first stage involves purging the gas from the external hydraulic lines of the brake. In the second stage, the liquid outlet valve and the pressure boosting valve at the wheel cylinder end are circulated and vented. The third stage is to expel the gas from the master cylinder; In the fourth stage, residual gas is vented in a directional manner through the wheel cylinder bleed bolt.

4. The automated air venting method for a hydraulic braking system as described in claim 3, characterized in that, In the first stage, the displacement loop control mode is used to drive the motor to push the brake fluid, control all the outlet valves, pressure boosting valves and isolation valves to be energized, the motor rotates forward to push the piston forward to the displacement limit and then reverses to retract; repeat the preset number of cycles to expel the gas in the external hydraulic pipeline of the brake.

5. The automated air venting method for a hydraulic braking system as described in claim 3, characterized in that, The second stage uses a torque loop control mode to drive the motor to build up pressure, controls the two isolation valves to remain energized throughout the entire second stage, controls the two booster valves to delay energization in each cycle, and controls each outlet valve to be energized in turn in a preset order in each cycle. After the target pressure is built up by the motor, the pressure difference is used to circulate and exhaust gas from the outlet valve and booster valve at the wheel cylinder end. The preset number of cycles is repeated to exhaust the gas in the upstream pipeline of each outlet valve and in the wheel cylinder.

6. The automated air venting method for a hydraulic braking system as described in claim 3, characterized in that, The third stage uses a displacement loop control mode to drive the motor to push the brake fluid, controlling all inlet valves and two booster valves to be energized simultaneously. The brake fluid flows along the path of booster valve, isolation valve, master cylinder to reservoir. After the motor's forward stroke ends, all solenoid valves are de-energized and active pressure building stops. After waiting for a preset time to stabilize the pressure in the pipeline, the motor reverses to retract and replenish the fluid. The preset number of cycles is repeated to expel the gas in the master cylinder.

7. The automated air venting method for a hydraulic braking system as described in claim 3, characterized in that, The fourth stage uses a torque loop control mode to drive the motor to build pressure, energize the inlet valves corresponding to the left rear wheel, the left front wheel, and the right front wheel, and de-energize the inlet valve corresponding to the right rear wheel; energize the outlet valve corresponding to the right rear wheel and de-energize the other three outlet valves; energize the first booster valve and de-energize the second booster valve; and construct a single hydraulic path from a specific wheel cylinder to the bleed bolt through a combination of solenoid valve states, allowing the brake fluid to carry residual gas and be discharged through the wheel cylinder bleed bolt.

8. The automated air venting method for a hydraulic braking system as described in claim 1, characterized in that, The host computer periodically sends status query commands to the ECU, including sending a query routine status sub-command to the ECU every 0.5s to 2s until feedback on the exhaust routine completion status is received.

9. The automated air venting method for a hydraulic braking system as described in claim 1, characterized in that, The host computer sends a second diagnostic command to the ECU, obtains the feedback pressure holding data, and determines whether the exhaust is qualified, including: The host computer sends a second diagnostic command to the ECU, controlling the ECU to build up pressure to a preset pressure and maintain pressure for a preset duration; the second diagnostic command is a pressure build-up and pressure maintenance verification command. The host computer obtains the pressure data during the pressure holding process through the pressure holding result query command, and judges the venting effect based on the pressure drop rate during the pressure holding period; if the pressure drop rate is lower than the preset threshold, the venting is deemed qualified and the venting process ends; if the pressure drop rate is higher than the preset threshold, the venting is deemed unqualified and the venting routine is automatically returned to be re-executed.

10. The automated air venting method for a hydraulic braking system as described in claim 9, characterized in that, When the exhaust is deemed unqualified, the procedure also includes: manually pressing the brake pedal to supplement the exhaust; after supplementing the exhaust, the pressure building and holding verification steps are repeated.

11. An automated exhaust system for a hydraulic braking system, characterized in that, This includes a braking system ECU; the ECU has a built-in automated exhaust software submodule, which includes a communication layer and an execution layer; The communication layer is used to receive diagnostic service routine instructions sent by the host computer, check the conditions that the exhaust routine needs to meet to enter the running state, including the vehicle stationary state, the actuator fault state, and the system voltage normal state, manage the running state and exit reasons of the exhaust routine, and feed back the current status information to the host computer. The execution layer is used to execute the automated venting method of the hydraulic braking system according to any one of claims 1-10.

12. A vehicle, characterized in that, The vehicle includes an automated exhaust system for the hydraulic braking system as described in claim 11, or performs an automated exhaust method for the hydraulic braking system as described in any one of claims 1-10.

13. An electronic device, characterized in that, include: Memory, used to store executable instructions; A processor, when executing executable instructions stored in the memory, implements the automated venting method of the hydraulic braking system according to any one of claims 1-10.

14. A computer-readable storage medium, characterized in that, The device stores executable instructions for causing a processor to execute the executable instructions to implement the automated venting method of the hydraulic braking system according to any one of claims 1-10.

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