Motor over-temperature control method and system of brake-by-wire system, and computer equipment

Abstract

The invention discloses a motor over-temperature control method and system of a brake-by-wire system, and computer equipment, and the method comprises the steps: detecting the temperature, power and loop pressure state of a motor in real time, and obtaining the over-temperature of the motor according to the target request pressure and the working state of the motor; when the motor is normal and the pressure of the pressure cylinder reaches the target pressure, the pressure cylinder isolation valve is actively closed, and the motor is controlled to withdraw and release the pressure; when the motor is overheated to reduce power or the pressure of the main cylinder exceeds the limit pressure building capacity of the motor, the main cylinder loop is switched to supply pressure; according to the scheme, self-adaptive control over the motor load is achieved, overheating degradation caused by long-time high load is avoided, braking continuity and safety in different thermal states are guaranteed, and the system reliability and the braking force upper limit are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of motor thermal protection, and particularly relates to a motor over-temperature control method and system for a brake-by-wire system and a computer device. BACKGROUND

[0002] The electronic hydraulic brake-by-wire system is composed of a master cylinder circuit and a booster cylinder circuit, wherein the master cylinder circuit is used for realizing pedal feeling simulation and backup braking, and the booster cylinder circuit is used for realizing normal brake-by-wire request; during system operation, the booster cylinder circuit is used to respond to active or passive braking demand through the action of a booster motor; generally, when braking on a large slope, a large braking torque is required; to respond to the large target braking torque demand, the motor needs to work in a high load state; long-term work in a high load state will cause system overheating, which is easy to trigger system overheating protection and cause system degradation or even failure.

[0003] For the existing brake-by-wire system, the driver's braking force request is responded by the booster motor of the brake-by-wire system; the greater the braking force request, the greater the motor working current, and therefore the greater the heat generated; when the vehicle brakes on a large slope, the motor needs a large working current to respond to the driver's braking force demand; the large working current causes the system to generate a large amount of heat loss, and the continuous accumulation of heat is easy to cause system overheating, which leads to power degradation or even system failure; motor power degradation and system failure will limit or lose the active pressure building capability of the braking system, affecting the safety of vehicle driving. SUMMARY

[0004] To solve the above problems, the application provides a motor over-temperature control method and system for a brake-by-wire system, which can actively adjust the motor load, dynamically switch the hydraulic passage, and realize the control method and system for system pressure building capability expansion, so as to ensure braking continuity and safety.

[0005] A motor over-temperature control method for a brake-by-wire system, which is used in an electronic hydraulic brake-by-wire system including a master cylinder circuit and a booster cylinder circuit; when the driver generates a braking request, the working state of the motor and the pressure state of the system are detected, including the following steps:

[0006] Normal pressure building condition of the braking system: when the motor is in a normal working state, the target pressure of the system output braking , the motor and the booster cylinder work, and the brake fluid is transmitted to the wheel end through the booster cylinder isolation valve and the booster valve to generate braking force;

[0007] Backup braking condition of the braking system: the booster cylinder hydraulic circuit is closed, and the hydraulic circuit of the master cylinder is opened, so that the hydraulic pressure generated in the master cylinder is transmitted to the wheel end for braking;

[0008] Prevent the brake system from overheating: when the motor is in normal working condition, the system outputs the target pressure of the brake greater than , the motor responds to the target pressure , the brake fluid is transmitted to the wheel end through the booster cylinder isolation valve and the booster valve of the circuit for braking, and after the response is completed, it enters the pressure maintaining state, the booster cylinder isolation valve is closed, and the motor is withdrawn at low speed to the position where the pressure of the booster cylinder is .

[0009] Overheating condition of the brake system: the motor power is degraded, and the maximum pressure building capacity of the motor and the booster cylinder is limited to , if the master cylinder pressure is greater than , the backup braking condition of the brake system is started; if the master cylinder pressure is less than , the target pressure is less than or equal to , the motor responds to the target pressure , and the transmission path of the brake system hydraulic pressure remains the transmission path of the motor in the normal working condition; if the master cylinder pressure is less than , the target pressure is greater than , the motor responds to the pressure , and the transmission path of the brake system hydraulic pressure remains the transmission path of the motor in the normal working condition.

[0010] Limiting pressure building condition of the brake system: when the master cylinder pressure is greater than the motor limiting pressure building pressure , the backup braking condition of the brake system is started.

[0011] It should be noted that:

[0012] In the overheating condition of the brake system, when the motor is limited under the condition of power degradation, when the target pressure is greater than the pressure limit , the master cylinder isolation valve is closed, the booster cylinder isolation valve is turned on, and the booster cylinder is pressurized to the pressure limit. At this time, only when the master cylinder pressure is greater than the maximum pressure building limit of the motor and the booster cylinder , the backup braking condition of the brake system is started.

[0013] The technical solution provided in the application also has the following technical features:

[0014] Preferably, in an embodiment of the application, the pressure maintaining condition: when the pressure of the booster cylinder is greater than the target pressure , the pressure maintaining stage is entered, the booster cylinder isolation valve is closed, and the motor is withdrawn at low speed, so that the pressure of the booster cylinder is .

[0015] Preferably, in an embodiment of the present application, when the master cylinder pressure is greater than the motor limit pressure , the backup braking condition of the braking system is started, the boost cylinder isolation valve is closed, the master cylinder isolation valve is turned on, and the driver's foot pressure is input to the wheel end through the master cylinder hydraulic circuit to increase the system braking force.

[0016] Preferably, in an embodiment of the present application, when the motor and the boost cylinder respond to reach , and the master cylinder pressure is greater than , the backup braking condition of the braking system is started.

[0017] Preferably, in an embodiment of the present application, the braking system state monitoring includes temperature sensing, power sensing and current acquisition modules for monitoring the target temperature state and triggering the overheat protection based on the preset temperature rise threshold.

[0018] Preferably, in an embodiment of the present application, the duration and temperature of the MOS tube current of the motor are monitored, and threshold values are set respectively to determine whether to limit the output power of the motor.

[0019] Preferably, in an embodiment of the present application, the MOS tube of the motor is equipped with a current sensor and a temperature sensor.

[0020] Preferably, in an embodiment of the present application, the motor speed and direction are adjusted during the motor retraction process to make the internal pressure of the boost cylinder decrease along a set curve.

[0021] Preferably, in an embodiment of the present application, a sensor is provided to identify the pressure maintaining condition.

[0022] Preferably, in an embodiment of the present application, a motor over-temperature control system of a brake-by-wire system applies the above-mentioned motor over-temperature control method of the brake-by-wire system, which includes:

[0023] A motor for driving a transmission mechanism to perform hydraulic pressure building and retraction;

[0024] A master cylinder and a master cylinder isolation valve, a boost cylinder and a boost cylinder isolation valve for responding to brake-by-wire requests;

[0025] A control unit for controlling the opening and closing of the boost cylinder isolation valve and the master cylinder isolation valve, the start and stop of the motor, and the working state of the master cylinder and the boost cylinder.

[0026] Preferably, in an embodiment of the present application, a thermal state prediction module is provided to predict the motor thermal saturation trend using motor temperature changes.

[0027] Preferably, in one embodiment of this application, a communication interface module is included for interacting with the vehicle controller to realize real-time monitoring and feedback of the motor thermal state and hydraulic circuit switching state.

[0028] Preferably, in one embodiment of this application, a computer device includes: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the above-described motor over-temperature control method of the brake-by-wire system.

[0029] Preferably, in one embodiment of this application, when the driver requests braking, if the braking system motor is operating normally and the actual pressure in the booster cylinder circuit is... To achieve the target request pressure When the pressure is high, the booster cylinder isolation valve is actively closed to isolate the booster cylinder and the wheel end. At the same time, the motor is controlled to actively retract to release the internal pressure of the booster cylinder to reduce the motor load. If the motor has triggered overheat protection and entered a power reduction state, the system will maintain its maximum pressure build-up capacity when the booster cylinder circuit pressure reaches the maximum pressure capacity of the system under motor-limited conditions, and the main cylinder pressure is greater than the booster cylinder pressure. Close the booster cylinder isolation valve and open the master cylinder isolation valve to input the master cylinder pressure applied by the driver's foot to the wheel end to continue responding to the target braking force request and ensure braking safety; at the same time, when the motor is working normally, if the master cylinder pressure is greater than the motor's limit pressure build-up pressure... At this time, the booster cylinder isolation valve is closed and the master cylinder isolation valve is opened, so that the pressure of the master cylinder pressed by the driver's foot is input to the brake wheel end to provide greater braking force.

[0030] Additional aspects and advantages 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.

[0031] The technical solution of this application has achieved the following technical advancements:

[0032] 1. To solve the problem of overheating and degradation caused by long-term high-load operation of the motor in the brake-by-wire system, a control method is adopted to actively close the isolation valve of the booster cylinder and control the motor to retract and release the pressure after the target pressure is reached. This overcomes the heat accumulation defect caused by the continuous high current operation of the motor in the traditional system, and achieves the technical effects of reducing the thermal load of the motor, extending the motor life and improving the reliability of the braking system.

[0033] 2. To address the issue of insufficient system pressure build-up when the motor enters a power-limited state due to overheating protection, a control method is adopted that switches to the main cylinder pressure input wheel after the pressure in the booster cylinder reaches the limit value. This overcomes the defect of the existing system in being unable to meet the driver's braking force request under power degradation state, and achieves the technical effect of ensuring braking safety even under motor-limited state.

[0034] 3. To solve the problem that the limit of motor build pressure capability is limited and the system cannot provide greater braking force, the means of detecting the master cylinder pressure and switching the hydraulic passage when the master cylinder pressure exceeds the limit of motor build pressure is adopted, which overcomes the limitation of traditional brake-by-wire system relying on motor assistance, and achieves the technical effect of improving the maximum build pressure capability and braking performance of the system.

[0035] 4. To solve the problem of system response lag and high energy consumption in the slope braking scene, the coordinated control strategy of phased closing and switching the isolation valve of the booster cylinder and the master cylinder is adopted, which overcomes the defects of uneven response and heat load accumulation caused by single build pressure path, and achieves the technical effect of improving the braking response speed and energy utilization efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0036] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the following drawings, in which:

[0037] Figure 1 is a schematic diagram of a vehicle braking on a slope;

[0038] Figure 2 is a schematic diagram of an electronic hydraulic brake-by-wire system of an embodiment;

[0039] Figure 3 is a schematic diagram of an electronic hydraulic brake-by-wire system of an embodiment;

[0040] Figure 4 is a schematic diagram of an electronic hydraulic brake-by-wire system of an embodiment;

[0041] Figure 5 is a schematic diagram of an electronic hydraulic brake-by-wire system of an embodiment;

[0042] Figure 6 is a schematic diagram of the hardware structure of a computer device of an embodiment of the present application. DETAILED DESCRIPTION

[0043] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate the present application, and are not limiting to the present application.

[0044] In the description of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0047] As Figures 1-5 , a motor over-temperature control method of a brake-by-wire system, for an electronic hydraulic brake-by-wire system including a master cylinder circuit and a booster cylinder circuit, when a driver generates a brake request, the motor operating state and the system pressure state are detected, including the following steps:

[0048] Normal pressure building condition of brake system: when the motor is in normal operating state, the target pressure of system output brake , the motor and the booster cylinder work, and the brake fluid is transmitted to the wheel end through the booster cylinder isolation valve and the booster valve to generate braking force;

[0049] Backup braking condition of brake system: the booster cylinder hydraulic circuit is closed, and the hydraulic circuit of the master cylinder is opened, so that the hydraulic pressure generated in the master cylinder is transmitted to the wheel end for braking;

[0050] Prevent overheating condition of brake system: when the motor is in normal operating state, the target pressure of system output brake is greater than , the motor responds to the target pressure , the brake fluid is transmitted to the wheel end through the booster cylinder isolation valve and the booster valve of the circuit for braking, and after the response is completed, it enters the pressure maintaining state, the booster cylinder isolation valve is closed, and the motor is withdrawn at low speed to the position where the pressure of the booster cylinder is ;

[0051] Brake system overheating condition: motor power degradation, the maximum pressure building capacity of the motor and the supercharging cylinder is limited to , if the master cylinder pressure is greater than , the backup braking condition of the brake system is started; the master cylinder pressure is less than , the target pressure is less than or equal to , the motor responds to the target pressure , the transmission path of the brake system hydraulic pressure remains the transmission path of the normal working state of the motor; when the master cylinder pressure is less than , the target pressure is greater than , the motor responds to the pressure , the transmission path of the brake system hydraulic pressure remains the transmission path of the normal working state of the motor;

[0052] Brake system limit supercharging condition: when the master cylinder pressure is greater than the motor limit pressure building pressure , the backup braking condition of the brake system is started;

[0053] The motor over-temperature control method of the brake-by-wire system can be summarized as "motor heat load monitoring -> state identification -> pressure building control switching -> master / supercharging circuit coordination -> heat prediction prevention", and the logical goal is to ensure the continuous braking ability and heat safety of the brake-by-wire system in a high load state;

[0054] The implementation points are that in the electronic hydraulic brake-by-wire system, by monitoring the motor temperature, working state and system pressure distribution in real time, combining the valve control strategy and circuit switching logic, the motor load adaptive adjustment and braking safety redundant control are realized;

[0055] Working principle:

[0056] State monitoring and judgment module: the system collects real-time data of the motor and hydraulic circuit through temperature sensors, current sensors and pressure sensors, and the control unit determines that the motor is in a normal, overheating or power degradation state according to the set temperature rise threshold and power limit;

[0057] Normal pressure building logic: when the motor works normally, the control unit drives the motor to drive the supercharging cylinder to execute pressure building, the hydraulic pressure is transmitted to the wheel end through the supercharging cylinder isolation valve and the supercharging valve to generate braking force, and the master cylinder circuit is kept open at the same time. State, through the pedal feeling simulator to provide natural pedal feeling, realize the coordination of brake-by-wire and mechanical feeling;

[0058] Overheating degradation control: when the motor temperature exceeds the preset threshold, the system automatically enters the overheating state; the control unit limits the output power of the motor to limit the system pressure building capacity to , to prevent the motor from working under high load for a long time and causing thermal saturation or failure;

[0059] Backup braking mode: the condition of entering backup braking when the system is powered off or the pressure building cylinder fails to build pressure;

[0060] Pressure maintaining condition: when the vehicle is braking on a slope and the target pressure , the system actively switches the hydraulic path, closes the master cylinder isolation valve, and opens the pressure building cylinder isolation valve, so that the pressure building cylinder performs high-pressure building; To prevent the motor from running under high load for a long time, the control unit immediately closes the pressure building cylinder isolation valve after detecting , and performs low-speed motor retraction to , achieving dynamic balance between pressure maintenance and thermal load removal.

[0061] Specifically, in an embodiment of the present application, the pressure maintaining condition is: when the pressure of the pressure building cylinder is greater than the target pressure , the pressure building cylinder isolation valve is closed, and the motor is retracted at low speed, so that the pressure of the pressure building cylinder is at the position of ;

[0062] To solve the problems of continuous high-load operation of the motor, system overheating, and insufficient braking force of the brake-by-wire system under high-load braking on a slope and in the state of motor thermal degradation, a double-valve coordinated control and motor low-speed retraction pressure regulation feature based on pressure determination is adopted. By real-time monitoring of the relative relationship among the pressure of the pressure building cylinder , the target pressure , and the pressure of the master cylinder, the control unit actively closes the pressure building cylinder isolation valve and controls the motor to retract at low speed in the reverse direction when , so that the pressure of the pressure building cylinder drops to , achieving active removal of the motor load and preventing the motor from being in a continuous high-pressure state. The thermal accumulation and degradation response lag defects caused by single-source pressure building of the motor in traditional brake-by-wire systems are overcome. Through valve control switching and motor retraction, load self-regulation and redundant assistance compensation are achieved, achieving the technical effects of reducing motor thermal load, prolonging motor life, and ensuring slope large-torque braking safety. In the implementation, the matching of valve response time and motor retraction speed should be ensured to prevent pressure fluctuations from causing braking decay. The motor low-speed retraction can be achieved through PWM speed regulation, servo control, or step micro-motion, and equivalent replacement solutions can use proportional valves with position feedback or controllable pressure relief valve modules to achieve the same pressure regulation and pressure maintenance functions.

[0063] Specifically, in an embodiment of the present application, the driver's foot pressure increases the system braking force, and when the pressure of the master cylinder is greater than the motor's limit building pressure , the backup braking condition of the braking system is started, the pressure building cylinder isolation valve is closed, the master cylinder isolation valve is opened, and the driver's foot pressure is input to the wheel end through the master cylinder hydraulic circuit to increase the system braking force.

[0064] Specifically, in an embodiment of the present application, the brake system state monitoring includes a temperature sensor, a power sensor and a current acquisition module for monitoring the target temperature state and triggering the overheat protection based on a preset temperature rise threshold;

[0065] The duration and temperature of the current of the MOS tube of the motor are monitored, and thresholds are set respectively to determine whether to limit the output power of the motor; the MOS tube of the motor is matched with a current sensor and a temperature sensor;

[0066] During the motor retraction process, the motor speed and direction are adjusted to make the internal pressure of the pressure boosting cylinder decrease along a set curve;

[0067] A sensor is arranged to identify the pressure maintaining condition;

[0068] To solve the problem that the brake-by-wire system cannot identify the thermal risk in time, cannot achieve smooth pressure relief and cannot identify the dynamic condition under complex slope and high temperature conditions, a multi-parameter fusion monitoring and adaptive pressure regulating control feature is adopted, the temperature sensor, the power sensor and the current acquisition module are used to realize real-time monitoring of the working thermal state of the motor, when the detected temperature rise exceeds the preset threshold, the control unit automatically triggers the overheat protection and enters the load reduction mode; during the motor retraction stage, the control unit dynamically adjusts the speed and direction of the motor based on the pressure sensor feedback, so that the internal pressure of the pressure boosting cylinder decreases smoothly along the set decay curve, avoiding uneven braking or pressure fluctuation caused by instantaneous pressure relief; at the same time, a slope identification sensor is arranged to identify the vehicle longitudinal slope and braking condition characteristics in real time, and automatically switch to the adaptive pressure maintaining condition or master cylinder assist mode combined with the system pressure state; this scheme overcomes the defects of the traditional system, such as the lag of the motor thermal state response and the roughness of the pressure regulation, realizes the closed-loop cooperation of the thermal protection and hydraulic control, and achieves the technical effects of improving the thermal response accuracy of the system, ensuring the smoothness of the slope braking and prolonging the service life of the motor; when implemented, the sampling frequency of the sensor signal and the control cycle should be consistent to prevent delay and misjudgment; the equivalent alternative scheme can use a virtual temperature estimation algorithm based on thermal model prediction to replace the physical temperature sensor, or use a proportional overflow valve to replace the motor reverse rotation pressure regulation to achieve the same effect.

[0069] Specifically, in an embodiment of the present application, a motor over-temperature control system of a brake-by-wire system applies the motor over-temperature control method of the brake-by-wire system, which includes:

[0070] A motor for driving a transmission mechanism to perform hydraulic pressure building and retraction;

[0071] A master cylinder and a master cylinder isolation valve, a pressure boosting cylinder and a pressure boosting cylinder isolation valve for responding to brake-by-wire requests;

[0072] A control unit for controlling the opening and closing of the pressure boosting cylinder isolation valve and the master cylinder isolation valve, the start and stop of the motor, and the working state of the master cylinder and the pressure boosting cylinder;

[0073] a thermal state prediction module is arranged to predict the motor thermal saturation trend using the motor temperature change;

[0074] a communication interface module is arranged to interact with the vehicle controller to realize real-time monitoring and feedback of the motor thermal state and the hydraulic passage switching state;

[0075] To solve the problems of the brake-by-wire system, such as insufficient prediction of motor over-temperature risk, lagging control response and poor system independence, an integrated control system structure is adopted, a coordinated control mechanism of the motor, the master cylinder and the booster cylinder and its isolation valve is arranged to realize accurate switching of the hydraulic pressure building and withdrawing process, and the control unit synchronously controls the motor start-stop and valve opening and closing according to the brake request signal to ensure the correctness and continuity of the brake pressure transmission path under different working conditions. Further, a thermal state prediction module is arranged to predict the thermal saturation trend by using the motor temperature change rate and power input data, and a load reduction or cooling strategy is executed in advance before the motor reaches the thermal critical point to avoid entering the forced degradation mode. The communication interface module interacts with the vehicle controller in real time to feed back the motor thermal state, system pressure and valve control state, and receives the vehicle thermal management and brake priority scheduling instructions to realize the vehicle-level thermal safety coordinated control. The scheme overcomes the defects of the traditional brake-by-wire system, such as relying only on passive temperature detection, lacking of prediction ability and independent control, and realizes active protection of motor over-temperature and system-level closed-loop control through modular thermal prediction and communication cooperation, thereby achieving the technical effects of improving the motor thermal response accuracy, shortening the control delay and improving the vehicle safety redundancy.

[0076] Specifically, in an embodiment of the present application, a computer device comprises a memory and a processor, which are communicatively connected with each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the motor over-temperature control method of the brake-by-wire system.

[0077] Specifically, in an embodiment of the present application, when the driver has a brake request, if the motor working state of the brake system is normal, and the actual pressure of the booster cylinder circuit is equal to the target request pressure, the booster cylinder isolation valve is actively closed to isolate the booster cylinder and the wheel end, and the motor is actively controlled to withdraw to release the pressure in the booster cylinder to reduce the load of the motor; if the motor has triggered the over-temperature protection to enter the power reduction state, when the pressure of the booster cylinder circuit reaches the maximum pressure building capacity of the system in the motor limited state, and the master cylinder pressure is greater than the booster cylinder pressure, the booster cylinder isolation valve is closed, the master cylinder isolation valve is opened, and the master cylinder pressure input by the driver is input to the wheel end to continue to respond to the target brake force request, thereby ensuring the brake safety; and when the motor working state is normal, if the master cylinder pressure is greater than the motor limit pressure building pressure , the booster cylinder isolation valve is actively closed, the master cylinder isolation valve is opened, and the master cylinder pressure input by the driver is input to the wheel end to continue to respond to the target brake force request, thereby ensuring the brake safety; and when the motor working state is normal, if the master cylinder pressure is greater than the motor limit pressure building pressure , the booster cylinder isolation valve is actively closed, the master cylinder isolation valve is opened, and the master cylinder pressure input by the driver is input to the wheel end to continue to respond to the target brake force request, thereby ensuring the brake safety; and when the motor working state is normal, if the master cylinder pressure is greater than the motor limit pressure building pressure​ At this time, the booster cylinder isolation valve is closed and the master cylinder isolation valve is opened, so that the pressure of the master cylinder pressed by the driver's foot is input to the brake wheel end to provide greater braking force.

[0078] Specifically, in one embodiment of this application, a method for controlling motor over-temperature in a brake-by-wire system includes the following operating conditions:

[0079] Normal pressure build-up condition of the braking system: Figure 2 The diagram shows an electro-hydraulic brake-by-wire system. The green path represents the working circuit. When the driver presses the pedal, the system outputs a target pressure request, the motor starts working, and drives the transmission mechanism to move forward. The brake fluid is transmitted to the wheel end through the pressure booster cylinder isolation valve and the pressure booster valve in the circuit to generate braking force. At the same time, the brake fluid in the master cylinder enters the pedal feel simulator and provides feedback on the pedal feel through the pedal feel simulator.

[0080] Braking system overheating condition: If the motor power is degraded due to overheating, the hydraulic pressure transmission path of the braking system remains unchanged, but the system's maximum pressure build-up capacity is limited. ,like Figure 3 As shown, the green path is the working circuit. When the system malfunctions and needs to be downgraded to the backup braking mode, the booster cylinder hydraulic circuit is closed, the pedal feel simulator is closed, and the master cylinder hydraulic circuit is opened, so that the hydraulic pressure generated in the master cylinder is transmitted to the wheel end for braking.

[0081] Figure 1 As shown, when a vehicle brakes on a slope, the control method proposed in this invention addresses the following two situations: when the motor is functioning normally and the target pressure... Greater than pressure limit When the driver depresses the pedal, the system controls the motor to drive the transmission mechanism in the forward direction. The master cylinder isolation valve closes, the booster cylinder isolation valve opens, and brake fluid is transmitted to the wheel ends through the booster cylinder isolation valve and the booster valve in the circuit for braking. When the booster cylinder pressure... greater than target pressure When the pressure holding stage begins, the pressure holding stage control method proposed in this invention is as follows: Figure 4 As shown, at this time, the pressure booster cylinder isolation valve is closed, forming a situation as follows: Figure 4 The circuit shown maintains pressure, while the motor retracts at low speed to the pressure limit set by the booster cylinder. The position should be adjusted to avoid the motor being under high load for extended periods, which could lead to overheating.

[0082] When the motor is operating normally, when the main cylinder pressure exceeds the motor's limit pressure build-up pressure In this case, the control method proposed by the present invention is as follows: Figure 5As shown, the booster cylinder isolation valve is closed, the master cylinder isolation valve is turned on, the driver's foot pressure is input to the wheel end through the master cylinder hydraulic circuit, and the driver's foot pressure is fully utilized to improve the maximum braking force of the system.

[0083] In the state of limited motor power, when the target pressure is greater than the pressure limit , the driver steps on the pedal, the system control assist motor drives the transmission mechanism to move forward, the booster cylinder isolation valve is closed, the booster cylinder isolation valve is turned on, the brake fluid is transmitted to the wheel end through the booster cylinder isolation valve and the booster valve of the circuit for braking, and the booster cylinder is pressurized to the pressure limit After that, the motor cannot continue to respond to the target braking request. The control method proposed in the present application in this case is as shown in Figure 5 When the master cylinder pressure is greater than the pressure limit , the booster cylinder isolation valve is closed, the master cylinder isolation valve is turned on, and the braking force is provided by the driver's foot through the master cylinder hydraulic circuit to meet the driver's deceleration demand.

[0084] The technical solution of the present application has the following technical progress:

[0085] Avoiding the long-time high-load working condition of the brake system assist motor to cause power degradation

[0086] When braking on a slope, after the actual pressure of the booster cylinder circuit reaches the target request pressure, the booster cylinder isolation valve is actively closed, the motor is actively withdrawn to release pressure and reduce the load of the motor, avoiding the long-time working of the motor in a high-load working condition to cause system degradation, improving the service life of the brake system assist motor, and ensuring the braking safety of the vehicle.

[0087] Fully utilizing the system pressure building capability in the state of limited motor power:

[0088] When the motor is in a power-limited state due to overheating protection, the booster cylinder circuit reaches the maximum pressure building capability and still cannot meet the target braking demand, when the master cylinder pressure is greater than the maximum pressure building limit of the motor and the booster cylinder , the booster cylinder circuit is actively closed, the master cylinder circuit is opened, and the master cylinder pressure of the driver's foot is transmitted to the wheel end to meet the driver's deceleration demand.

[0089] Further improving the maximum pressure building capability of the system after the motor reaches the maximum power:

[0090] When the pressure generated by the driver's foot is greater than the pressure generated by the motor reaching the maximum power, the booster cylinder circuit is actively closed, the master cylinder circuit is opened, and greater pressure is provided to the wheel end, improving the maximum pressure building capability of the system.

[0091] When the driver brakes on a slope and the braking request is large, if the braking system assist motor is in a normal working state, the boost cylinder loop isolation valve is actively closed when the actual pressure of the boost cylinder loop reaches the target pressure request state, the internal pressure of the boost cylinder is released, the load of the motor is reduced, and the motor overheating is avoided; when the braking system assist motor is in a power limited state, the boost cylinder loop is actively closed and the master cylinder loop is opened when the boost cylinder loop reaches the maximum pressure building capacity, and the master cylinder pressure is transmitted to the wheel end to respond to the deceleration demand; when the braking system assist motor is in a normal working state, the boost cylinder loop is actively closed and the master cylinder loop is opened when the master cylinder pressure is greater than the maximum pressure provided by the system, and the master cylinder pressure is transmitted to the wheel end to improve the maximum pressure building capacity of the system. The control method can avoid triggering power degradation of the braking system assist motor due to overheating, meet the deceleration demand of the driver after the motor power degradation, and improve the maximum pressure building capacity of the system after the motor reaches the maximum power.

[0092] Specifically, in one embodiment of the present application, Figure 6 is a structural schematic diagram of a computer device provided by an optional embodiment of the present application, as Figure 6 shown, the computer device includes one or more processors 10, a memory 20, and an interface for connecting various components, including a high-speed interface and a low-speed interface. Various components are communicatively connected to each other by using different buses, and can be installed on a common mainboard or in other ways as needed. The processor can process instructions executed in the computer device, including instructions stored in the memory or the memory to display graphical information on a GUI on an external input / output device, such as a display device coupled to the interface. In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used with multiple memories and multiple memories. Also, multiple computer devices can be connected, each providing part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 In the figure, the processor 10 is taken as an example.

[0093] The processor 10 can be a central processor, a network processor, or a combination thereof. The processor 10 can further include a hardware chip. The hardware chip can be an application specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device can be a complex programmable logic device, a field programmable logic gate array, a general array logic, or any combination thereof.

[0094] The memory 20 stores instructions executable by the at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiments.

[0095] The memory 20 can include a program storage area and a data storage area, where the program storage area can store an operating system, application programs required for at least one function, and the data storage area can store data created according to the use of the computer device, etc. In addition, the memory 20 can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some alternative embodiments, the memory 20 can optionally include a memory disposed remotely from the processor 10, which can be connected to the computer device through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0096] The memory 20 can include a volatile memory, such as a random access memory, and can also include a non-volatile memory, such as a flash memory, a hard disk, or a solid state disk, and can also include a combination of the above-mentioned types of memories.

[0097] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30, and the output device 40 can be connected by a bus or other means, Figure 6 The connection by the bus is taken as an example.

[0098] The input device 30 can receive inputted digital or character information, and generate key signal inputs related to the user settings and function controls of the computer device, such as a touch screen, a keypad, a mouse, a trackpad, a touchpad, a pointing stick, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 can include a display device, an auxiliary lighting device (e.g., an LED), a tactile feedback device (e.g., a vibration motor), etc. The display device includes, but is not limited to, a liquid crystal display, a light-emitting diode, a display, and a plasma display. In some alternative embodiments, the display device can be a touch screen.

[0099] The embodiments of the present application also provide a computer readable storage medium, and the method according to the embodiments of the present application can be implemented in hardware, firmware, or recorded in a storage medium, or stored in a remote storage medium or a non-transitory machine readable storage medium and downloaded to a local storage medium, so that the method described herein can be processed by such software on a storage medium using a general purpose computer, a special purpose processor or programmable or special hardware. The storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk or a solid state disk, etc. Further, the storage medium can also include a combination of the above-mentioned memories. It can be understood that the computer, processor, microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code, which, when accessed and executed by the computer, processor or hardware, implements the method shown in the above embodiments.

[0100] Part of the present application can be applied as a computer program product, for example, computer program instructions, when executed by a computer, through the operation of the computer, the method and / or technical solutions according to the present application can be called or provided. Those skilled in the art should understand that the form of computer program instructions in computer readable medium includes but is not limited to source file, executable file, installation package file, etc. Correspondingly, the way of computer program instructions executed by computer includes but is not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Here, the computer readable medium can be any available computer readable storage medium or communication medium accessible to the computer.

[0101] In general, the present application aims to solve the problem that the booster motor in the existing electronic hydraulic brake-by-wire system is prone to be in a high load state for a long time in the scene of large slope braking or high braking force demand, resulting in overheating protection triggering, system power degradation and braking response ability decline. The present application establishes a coordinated control logic of motor working state and hydraulic circuit, actively closes the booster cylinder isolation valve and controls the motor to retreat to reduce the load when the motor works normally, automatically switches to the master cylinder circuit to continue to provide braking force in the motor overheating power reduction state, and realizes master cylinder pressure priority when the master cylinder pressure exceeds the motor limit pressure building capacity, so as to realize motor thermal load adaptive adjustment, system pressure building capacity dynamic expansion and continuous guarantee of braking safety.

[0102] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and replacements can be made without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A method for controlling motor over-temperature in a brake-by-wire system, used in an electro-hydraulic brake-by-wire system including a master cylinder circuit and a booster cylinder circuit, wherein when the driver generates a braking request, the method detects the motor operating status and the system pressure status, characterized in that, Includes the following steps: Normal pressure build-up condition of the braking system: When the motor is in normal working condition, the system outputs the target braking pressure. When the motor and booster cylinder are working, the brake fluid is transmitted to the wheel end through the booster cylinder isolation valve and booster valve to generate braking force; Backup braking mode of the braking system: The hydraulic circuit of the booster cylinder is closed, and the hydraulic circuit of the master cylinder is opened, so that the hydraulic pressure generated in the master cylinder is transmitted to the wheel end for braking; Preventing overheating of the braking system: When the motor is in normal operating condition, the system outputs the target braking pressure. Greater than The motor responds to the target pressure The brake fluid is delivered to the wheel ends via the booster cylinder isolation valve and the booster valve in the circuit for braking. After the response is complete, it enters a pressure-holding state, closes the booster cylinder isolation valve, and the motor retracts at low speed to the pressure in the booster cylinder. Location; Braking system overheating condition: Motor power degrades, and the maximum pressure build-up capacity of the motor and booster cylinder is limited. If the master cylinder pressure is greater than Start the braking system to backup braking conditions; master cylinder pressure is less than Target pressure Less than or equal to The motor responds to the target pressure The hydraulic pressure transmission path of the braking system remains the same as that of the motor under normal operating conditions; the master cylinder pressure is less than... Target pressure Greater than At that time, the motor responds to the pressure The hydraulic pressure transmission path of the braking system remains the same as the transmission path of the motor under normal operating conditions. Braking system overpressure limit condition: when the master cylinder pressure exceeds the motor's limit pressure build-up. When necessary, the braking system is activated to back up the braking conditions.

2. The motor over-temperature control method for a brake-by-wire system as described in claim 1, characterized in that, Pressure holding condition: when the pressure of the booster cylinder is... greater than target pressure When the pressure holding phase begins, the pressure booster cylinder isolation valve closes, and the motor retracts at low speed, bringing the pressure in the pressure booster cylinder to [value missing]. The location.

3. The motor over-temperature control method for a brake-by-wire system as described in claim 2, characterized in that, The braking system status monitoring includes temperature sensing, power sensing and current acquisition modules, which are used to monitor the target temperature status and trigger overheat protection based on a preset temperature rise threshold.

4. The motor over-temperature control method for a brake-by-wire system as described in claim 3, characterized in that, Monitor the duration and temperature of the current in the motor's MOSFET, and set thresholds for each to determine whether to limit the motor's output power.

5. The motor over-temperature control method for a brake-by-wire system as described in claim 4, characterized in that, The motor's MOSFET is equipped with a current sensor and a temperature sensor.

6. The motor over-temperature control method for a brake-by-wire system as described in claim 1, characterized in that, During the motor retraction process, the internal pressure of the booster cylinder is reduced along a set curve by adjusting the motor speed and direction.

7. The motor over-temperature control method for a brake-by-wire system as described in claim 1, characterized in that, Sensors are installed to identify pressure-holding conditions.

8. A motor over-temperature control system for a brake-by-wire system, employing the motor over-temperature control method for a brake-by-wire system according to any one of claims 1 to 7, characterized in that, include: The electric motor is used to drive the transmission mechanism to perform hydraulic pressure building and retraction; Master cylinder and master cylinder isolation valve, booster cylinder and booster cylinder isolation valve, used to respond to brake-by-wire requests; The control unit controls the opening and closing of the booster cylinder isolation valve and the main cylinder isolation valve, the start and stop of the motor, and the working status of the main cylinder and the booster cylinder.

9. The motor over-temperature control system of the brake-by-wire system as described in claim 8, characterized in that, Includes a communication interface module and a thermal state prediction module; The communication interface module is used to interact with the vehicle controller to achieve real-time monitoring and feedback of the motor thermal state and hydraulic circuit switching state. The thermal state prediction module uses changes in motor temperature to predict the motor's thermal saturation trend.

10. A computer device, characterized in that, include: The system includes a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the motor over-temperature control method of any one of claims 1 to 7.

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