Method and system for processing piston top contact of fully decoupled wire-controlled brake system

Abstract

The present invention discloses a method and system for processing a piston top contact of a fully decoupled brake-by-wire system, which relates to the field of vehicle braking technology, and includes: detecting whether the system is powered on normally; if not, entering a mechanical backup braking mode; if so, determining whether there is a fault; if so, entering a mechanical backup braking mode; if not, determining whether it is in a braking state; if not, entering a normal brake-by-wire mode; if so, determining whether the servo cylinder piston has top contact; if not, entering a normal brake-by-wire mode; if so, reporting an abnormality and determining whether the vehicle speed is greater than a first threshold; if so, entering an ESC brake compensation mode; if not, entering a top contact degradation control mode. Aiming at the problem that the braking force output cannot be further increased after the servo cylinder piston has top contacted during braking, the present invention proposes adopting different braking control methods according to the vehicle speed, thereby improving the safety of driving during static and dynamic braking.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and in particular to a method and system for processing piston top contact in a fully decoupled wire-controlled brake system. Background Art

[0002] The continuous development of electric smart cars has put forward higher safety and stability requirements for the chassis braking system of the car, requiring the chassis braking system to have fast and precise control capabilities. However, traditional vacuum boosters and electronic stability control systems have problems such as response speed decay and pressure control error fluctuation during continuous and active control. Therefore, major domestic and foreign institutions have proposed a variety of wire control brake solutions, such as DBS (Decoupled Brake System) to meet the new requirements of electric smart cars.

[0003] refer to Figure 1 , Figure 1 This is a schematic diagram of the system principle of DBS. After DBS is powered on, all solenoid valves are powered on and activated. At this time, after stepping on the pedal, the hydraulic pressure generated by manpower will be maintained before the isolation valve of the manual cylinder circuit, and the hydraulic circuit after the isolation valve of the manual cylinder circuit will maintain the pressure generated by the servo motor driving the transmission mechanism to push the servo cylinder piston forward. When the following situations occur, it will cause insufficient braking force during DBS wire control braking: 1) The PV characteristics of the vehicle's braking system are poor, such as insufficient exhaust or the vehicle's own braking system requires a large amount of fluid. At this time, when establishing the specified target pressure, a larger servo cylinder piston stroke is required to establish the corresponding braking system pressure; 2) There is excessive wear of the servo cylinder piston cup, resulting in the servo cylinder piston being gradually pushed to the top of the servo cylinder due to poor sealing in order to maintain the braking pressure during the braking process, resulting in insufficient subsequent braking force; 3) Brushless motors usually do not have an external position sensor. When used, the servo cylinder piston position needs to be calculated based on the rotor angle. Mechanical zeroing is required every time the power is turned on before it can be used normally. If there was an abnormal power outage when the vehicle was used last time, causing the servo cylinder piston position to be too far away from the servo cylinder mechanical zero point, when the pressure is built up directly according to the brake target pressure before the motor completes the homing action, the forward piston stroke is not enough to generate the corresponding target pressure, but at this time it has touched the top of the servo cylinder body, resulting in the inability to further compress the brake fluid to build pressure, thereby causing insufficient braking force.

[0004] In order to solve the problem of insufficient braking force, the prior art provides protection by limiting the motor torque to prevent the motor torque from being too large when the servo cylinder piston is pushed to the top of the piston cylinder body, thereby damaging the transmission mechanism and the servo cylinder body. However, when the braking force is insufficient due to the above reasons, only performing mechanism protection may lead to risks caused by insufficient braking force under certain working conditions, such as longer braking distance or slipping. Summary of the invention

[0005] The present invention provides a method and system for processing piston top contact in a fully decoupled brake-by-wire system, so as to overcome at least one technical problem existing in the prior art.

[0006] On the one hand, an embodiment of the present invention provides a method for processing piston top contact in a fully decoupled wire-controlled brake system, comprising:

[0007] Determine whether the fully decoupled brake-by-wire system is powered on normally;

[0008] When the fully decoupled brake-by-wire system is not powered on normally, it enters the mechanical backup brake mode and the program ends;

[0009] When the fully decoupled brake-by-wire system is powered on normally, detecting whether the fully decoupled brake-by-wire system has a fault;

[0010] When a fault occurs in the fully decoupled brake-by-wire system, the system enters the mechanical backup brake mode and determines whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault.

[0011] When there is no fault in the fully decoupled brake-by-wire system, detecting whether the fully decoupled brake-by-wire system is in a braking state;

[0012] When the fully decoupled brake-by-wire system is not in a braking state, the normal brake-by-wire mode is entered, and it is determined whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault;

[0013] When the fully decoupled brake-by-wire system is in the braking state, determine whether the servo cylinder piston has touched the top;

[0014] If the servo cylinder piston does not touch the top, the normal wire control brake mode is entered, and it is determined whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled wire control brake system has a fault;

[0015] If the servo cylinder piston touches the top, an abnormality is reported and it is determined whether the vehicle speed is less than a first threshold;

[0016] When the vehicle speed is greater than the first threshold, the ESC brake compensation mode is entered, and it is determined whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled wire control brake system has a fault;

[0017] When the vehicle speed is less than or equal to the first threshold, the top-out degradation control mode is entered, and it is determined whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system.

[0018] Optionally, detecting whether the fully decoupled brake-by-wire system has a fault is specifically performed as follows:

[0019] Check whether the servo motor, manual cylinder circuit isolation valve, and servo cylinder circuit isolation valve are faulty.

[0020] Optionally, judging whether the servo cylinder piston has touched the top is specifically as follows:

[0021] According to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is judged whether the servo cylinder piston has touched the top: when the change of the servo motor torque output value exceeds the second threshold value and the servo cylinder piston stroke remains unchanged, it indicates that the servo cylinder piston has touched the top; conversely, when the servo cylinder piston stroke changes with the change of the servo motor torque output value, it indicates that the servo cylinder piston has not touched the top.

[0022] Optionally, the top-out degradation control mode is specifically:

[0023] Collect the initial value of the servo cylinder pressure sensor P2;

[0024] Close the servo cylinder circuit isolation valve;

[0025] Control the servo motor to reverse, drive the transmission mechanism to drive the servo cylinder piston to retreat by a stroke s;

[0026] The servo motor is controlled to rotate forward, and the transmission mechanism is driven to push the servo cylinder piston forward. At the same time, the measured value of the servo cylinder pressure sensor P2 is detected. When the measured value of the servo cylinder pressure sensor P2 reaches the initial value, the servo cylinder circuit isolation valve is opened.

[0027] Optionally, before entering the ESC brake compensation mode, the following steps are also included:

[0028] Check whether ESC supports brake compensation. If not, enter the top-out degradation control mode; if yes, enter the ESC brake compensation mode.

[0029] On the other hand, the present invention further provides a fully decoupled brake-by-wire system piston top-contact processing system, comprising:

[0030] A judgment module, used to judge whether the fully decoupled brake-by-wire system is powered on normally;

[0031] A control module, used for controlling the full decoupled brake-by-wire system to enter a mechanical backup braking mode when the system is not powered on normally, and the program ends;

[0032] A detection module, used for detecting whether the fully decoupled brake-by-wire system has a fault when the fully decoupled brake-by-wire system is normally powered on;

[0033] When a fault occurs in the fully decoupled brake-by-wire system, the control module is further used to control the entry into the mechanical backup braking mode and determine whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether a fault occurs in the fully decoupled brake-by-wire system.

[0034] When there is no fault in the fully decoupled brake-by-wire system, the detection module is further used to detect whether the fully decoupled brake-by-wire system is in a braking state;

[0035] When the fully decoupled brake-by-wire system is not in a braking state, the control module is further used to control the entry into a normal brake-by-wire mode and determine whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault;

[0036] When the fully decoupled brake-by-wire system is in a braking state, the judgment module is also used to judge whether the servo cylinder piston has touched the top;

[0037] If the servo cylinder piston does not touch the top, the control module is also used to control the entry into the normal wire control brake mode and determine whether the power is off. If so, the program ends; if not, jump to the step of detecting whether the fully decoupled wire control brake system has a fault;

[0038] The reporting module is used to report an abnormality if the servo cylinder piston touches the top;

[0039] The judging module is used to judge whether the vehicle speed is less than a first threshold;

[0040] When the vehicle speed is greater than the first threshold, the control module is further used to control the entry into the ESC brake compensation mode and determine whether the power is turned off. If so, the program ends; if not, jump to the step of detecting whether there is a fault in the fully decoupled wire control brake system;

[0041] When the vehicle speed is less than or equal to the first threshold, the control module is also used to control the entry into the top-out degradation control mode and determine whether the power is turned off. If so, the program ends; if not, it jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system.

[0042] Optionally, when detecting whether the fully decoupled brake-by-wire system has a fault, the detection module is specifically used to:

[0043] Check whether the servo motor, manual cylinder circuit isolation valve, and servo cylinder circuit isolation valve are faulty.

[0044] Optionally, when judging whether the servo cylinder piston has touched the top, the judging module is specifically used to:

[0045] According to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is judged whether the servo cylinder piston has touched the top: when the change of the servo motor torque output value exceeds the second threshold value and the servo cylinder piston stroke remains unchanged, it indicates that the servo cylinder piston has touched the top; conversely, when the servo cylinder piston stroke changes with the change of the servo motor torque output value, it indicates that the servo cylinder piston has not touched the top.

[0046] Optionally, when executing the top-out degradation control mode, the method further includes:

[0047] The acquisition module is used to acquire the initial value of the servo cylinder pressure sensor P2;

[0048] A closing module, used to close the servo cylinder circuit isolation valve;

[0049] A driving module, used to control the servo motor to reverse and drive the transmission mechanism to drive the servo cylinder piston to retreat by a stroke s;

[0050] The driving module is also used to control the forward rotation of the servo motor, drive the transmission mechanism to push the servo cylinder piston forward, and simultaneously detect the measurement value of the servo cylinder pressure sensor P2. When the measurement value of the servo cylinder pressure sensor P2 reaches the initial value, the servo cylinder circuit isolation valve is opened.

[0051] Optionally, the detection module is further used to detect whether the ESC supports brake compensation before entering the ESC brake compensation mode, and if not, enter the top-out degradation control mode; if so, enter the ESC brake compensation mode.

[0052] The innovative features of the embodiments of the present invention include:

[0053] 1. In this embodiment, in view of the problem that the braking force output of the fully decoupled brake-by-wire system may not be able to be further increased after the servo cylinder piston touches the top during braking, it is proposed to adopt different braking control methods according to the vehicle speed, thereby improving the safety of static and dynamic braking driving, which is one of the innovations of the embodiment of the present invention.

[0054] 2. In the present embodiment, when the vehicle is close to being stationary, the solenoid valve and the servo motor are coordinated to perform top-down control, thereby realizing a relay and step-by-step increase in brake pressure. This can avoid ESC brake compensation action while meeting the braking demand, which is beneficial to reducing system complexity and is one of the innovative points of the present invention embodiment.

[0055] 3. In this embodiment, when the servo cylinder piston touches the top, the present invention notifies the driver of a fault by reporting the abnormality, thereby saving the driver's reaction time and allowing the driver to take deceleration and stop measures such as parking brakes earlier, which is one of the innovative features of the embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 A schematic diagram of a DBS system principle;

[0058] Figure 2 A flow chart of a piston top contact processing method provided by an embodiment of the present invention;

[0059] Figure 3 A schematic diagram of a structure of a servo cylinder piston touching the top provided by an embodiment of the present invention;

[0060] Figure 4 A schematic diagram of a relationship curve between the servo cylinder piston stroke and the servo motor torque output value provided in an embodiment of the present invention;

[0061] Figure 5 A flow chart of a top-out degradation control mode provided by an embodiment of the present invention;

[0062] Figure 6 A timing diagram of a top-out degradation control mode provided by an embodiment of the present invention;

[0063] Figure 7 Another flow chart of the piston top contact processing method provided by the embodiment of the present invention;

[0064] Figure 8 A schematic diagram of the structure of a piston top contact processing system provided by an embodiment of the present invention;

[0065] Fig. 9 Another structural schematic diagram of the piston top contact processing system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0068] The embodiment of the present invention discloses a method for processing piston top contact in a fully decoupled brake-by-wire system, which is described in detail below.

[0069] Figure 2 A flow chart of a piston top contact processing method provided by an embodiment of the present invention, referring to Figure 2 The method for processing piston top contact of a fully decoupled brake-by-wire system provided by an embodiment of the present invention comprises:

[0070] Step 1: Determine whether the fully decoupled brake-by-wire system is powered on normally;

[0071] Step 2: When the fully decoupled brake-by-wire system is not powered on normally, the mechanical backup brake mode is entered and the procedure ends;

[0072] Step 3: When the fully decoupled brake-by-wire system is powered on normally, detect whether the fully decoupled brake-by-wire system has a fault;

[0073] Step 4: When there is a fault in the fully decoupled brake-by-wire system, enter the mechanical backup brake mode and determine whether the power is off. If so, the program ends; if not, jump to the step of detecting whether there is a fault in the fully decoupled brake-by-wire system;

[0074] Step 5: When there is no fault in the fully decoupled brake-by-wire system, detect whether the fully decoupled brake-by-wire system is in a braking state;

[0075] Step 6: When the fully decoupled brake-by-wire system is not in a braking state, the normal brake-by-wire mode is entered, and it is determined whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault;

[0076] Step 7: When the fully decoupled brake-by-wire system is in a braking state, determine whether the servo cylinder piston has touched the top;

[0077] Step 8: If the servo cylinder piston does not touch the top, the normal brake-by-wire mode is entered, and it is determined whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether there is a fault in the fully decoupled brake-by-wire system;

[0078] Step 9: If the servo cylinder piston touches the top, an abnormality is reported, and it is determined whether the vehicle speed is less than the first threshold;

[0079] Step 10: When the vehicle speed is greater than the first threshold, the ESC brake compensation mode is entered, and it is determined whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system;

[0080] Step 11: When the vehicle speed is less than or equal to the first threshold, the top-out degradation control mode is entered, and it is determined whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system.

[0081] It should be noted that in steps 4, 6, 8, 10 and 11, it is necessary to determine whether to power off. Therefore, in order to avoid interference, Figure 2 The power-off procedures in the above steps are combined into the same block diagram.

[0082] Specifically, refer to Figure 1 The fully decoupled brake-by-wire system includes a fluid reservoir, a servo cylinder isolation valve, a servo cylinder pressure sensor P2, a servo cylinder body, a servo cylinder piston, a transmission mechanism, a servo motor, a manual cylinder circuit isolation valve, and a one-way valve. The rest is a brake fluid circuit and related filters, and the circuit is filled with brake fluid. Of course, in addition to the above, the fully decoupled brake-by-wire system also includes a brake pedal, a mechanical push rod, a travel sensor, a first piston and spring of the manual cylinder, a second piston and spring of the manual cylinder, a manual cylinder pressure sensor P1, a simulation cylinder circuit isolation valve, a simulation cylinder, and other components not marked in the figure.

[0083] refer to Figure 2 , the piston top-touching processing method of the fully decoupled wire-controlled brake system provided by the embodiment of the present invention, after the DBS is powered on, all the solenoid valves are powered on and work. In order to ensure that they can work normally, firstly, step 1 is performed to determine whether the fully decoupled wire-controlled brake system is powered on normally.

[0084] When the fully decoupled brake-by-wire system is not powered on normally, in step 2, the fully decoupled brake-by-wire system enters the mechanical backup braking mode. At this time, since the fully decoupled brake-by-wire system is not powered on normally, this step does not involve any control strategy and the program ends directly.

[0085] When the fully decoupled brake-by-wire system is powered on normally, it is necessary to determine whether the fully decoupled brake-by-wire system has a fault. Therefore, this embodiment detects whether the fully decoupled brake-by-wire system has a fault through step 3. Here, the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve in the fully decoupled brake-by-wire system can be detected respectively. When any one of them fails, it is considered that the fully decoupled brake-by-wire system has a fault.

[0086] When the fully decoupled brake-by-wire system fails, it cannot work normally. Therefore, in this embodiment, the fully decoupled brake-by-wire system enters the mechanical backup braking mode through step 4. After entering the mechanical backup braking mode, the motor and all solenoid valves are not controlled. It is determined whether to power it off. If it is powered off, the program ends; if it is not powered off, it jumps to step 3 to detect whether the fully decoupled brake-by-wire system has a fault again and perform subsequent operations.

[0087] When the fully decoupled brake-by-wire system has no faults, it indicates that it can work normally. At this time, it is necessary to determine whether it is currently in a braking state. Therefore, in step 5, this embodiment detects whether the fully decoupled brake-by-wire system is in a braking state.

[0088] When the fully decoupled brake-by-wire system is not in a braking state, there is no problem of insufficient braking force during braking. Therefore, in this embodiment, through step 6, the fully decoupled brake-by-wire system enters the normal brake-by-wire mode, at which time there is no brake pressure target. It is determined whether to power it off. If it is powered off, the program ends. If it is not powered off, jump to step 3, check again whether the fully decoupled brake-by-wire system has a fault, and perform subsequent operations.

[0089] When the fully decoupled brake-by-wire system is in a braking state, it is necessary to determine the current position state of the servo cylinder piston. Therefore, in this embodiment, step 7 is used to determine whether the servo cylinder piston has touched the top. The top touch check can be determined by comprehensively analyzing the relationship between the servo cylinder piston stroke, the actual motor torque, the actual motor torque change rate, the actual motor speed and other signals.

[0090] If the servo cylinder piston does not touch the top, the servo cylinder piston can continue to be pushed forward to build pressure. Therefore, when the servo cylinder piston does not touch the top, this embodiment passes step 8 to make the fully decoupled brake-by-wire system enter the normal brake-by-wire mode. At this time, since the fully decoupled brake-by-wire system is in a braking state, after entering the normal brake-by-wire mode, the fully decoupled brake-by-wire system will normally build pressure according to the target braking pressure. In the brake-by-wire mode, determine whether to power it off. If it is powered off, the program ends; if it is not powered off, jump to step 3, check again whether the fully decoupled brake-by-wire system has a fault, and perform subsequent operations.

[0091] Figure 3 A schematic diagram of a structure of a servo cylinder piston touching the top provided by an embodiment of the present invention, referring to Figure 3If the servo cylinder piston touches the top, even if the servo motor output torque continues to increase, the servo cylinder piston stroke will not increase. At this time, the servo cylinder piston pressure-building stroke is insufficient, resulting in the inability to establish the corresponding target pressure. Therefore, when the servo cylinder piston touches the top, this embodiment reports the relevant work abnormality through step 9, prompting the driver that a fault has occurred, saving the driver's reaction time, so that the driver can take deceleration and stop measures such as parking brakes earlier.

[0092] In this embodiment, when the abnormality is reported, the execution action after the top is touched is determined by comparing the vehicle speed with the first threshold. Here, the first threshold may be, for example, 1 km / h, which may be set according to actual conditions and is not specifically limited here.

[0093] When the vehicle speed is greater than the first threshold value, assuming that the first threshold value is 1km / h, when the vehicle speed is greater than 1km / h, it means that the vehicle is currently in a dynamic driving state. Since the pressure at the wheel end will be maintained instead of continuing to increase during the period when the servo cylinder circuit isolation valve is closed and the motor retreats to replenish fluid. Therefore, when the vehicle is in a dynamic driving state, this implementation uses step 10 to make the fully decoupled wire control brake system enter the ESC (Electronic Stability Control System) brake compensation mode, and actively builds pressure by extracting brake fluid from the corresponding circuits of the two one-way valves of the fully decoupled wire control brake system, thereby realizing auxiliary pressure building for the fully decoupled wire control brake system. In this step, it is also determined whether to power it off. If it is powered off, the program ends; if it is not powered off, jump to step 3, and check again whether there is a fault in the fully decoupled wire control brake system, and perform subsequent operations.

[0094] When the vehicle speed is less than or equal to the first threshold, assuming that the first threshold is 1km / h, then when the vehicle speed is less than or equal to 1km / h, it indicates that the vehicle is currently in a nearly stationary state. At this time, since the pressure has not reached the target brake pressure, this embodiment uses step 11 to make the fully decoupled brake-by-wire system enter the top-out degradation control mode, and compresses more brake fluid to build pressure by controlling the servo cylinder to retreat and replenish fluid and then push forward, thereby reaching the target brake pressure. In this step, it is also determined whether to power off the system. If it is powered off, the program ends; if it is not powered off, jump to step 3, and check again whether the fully decoupled brake-by-wire system has a fault, and perform subsequent operations.

[0095] The method for handling the piston top contact of a fully decoupled brake-by-wire system provided in an embodiment of the present invention aims to solve the problem that the brake force output may not be further increased after the servo cylinder piston touches the top during braking in a fully decoupled brake-by-wire system. Different braking control methods are proposed according to the vehicle speed, thereby improving the safety of driving during static and dynamic braking. When the vehicle is close to a standstill, the brake pressure is relayed and stepped up by coordinating the top contact degradation control of the solenoid valve and the servo motor, which can avoid the ESC brake compensation action while meeting the braking demand, thereby helping to reduce the complexity of the system. In addition, when the servo cylinder piston touches the top, the present invention notifies the driver of a fault by reporting an abnormality, thereby saving the driver's reaction time and allowing the driver to take deceleration measures such as parking brakes earlier.

[0096] Optionally, refer to Figure 2 In step 7, it is determined whether the servo cylinder piston has touched the top, specifically: according to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is determined whether the servo cylinder piston has touched the top: when the change of the servo motor torque output value exceeds the second threshold value, and the servo cylinder piston stroke remains unchanged, it indicates that the servo cylinder piston has touched the top; conversely, when the servo cylinder piston stroke changes with the change of the servo motor torque output value, it indicates that the servo cylinder piston has not touched the top.

[0097] Specifically, the top contact check can be determined by comprehensively analyzing the relationship between the servo cylinder piston stroke, the actual motor torque, the actual motor torque change rate, the actual motor speed and other signals. Figure 4 As shown, Figure 4 A schematic diagram of a relationship curve between the servo cylinder piston stroke and the servo motor torque output value provided in an embodiment of the present invention.

[0098] According to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is determined whether the servo cylinder piston has reached the top. Figure 4 When it is detected that the servo cylinder piston stroke no longer increases, but the servo motor torque output value still increases, and the increase exceeds a certain threshold, it is determined that the servo cylinder piston has touched the top. Here, the threshold is set to the second threshold, and the specific value of the second threshold can be set according to actual conditions and is not specifically limited here.

[0099] Continue to refer Figure 4 When the servo cylinder piston does not touch the top, as the servo motor torque increases, the servo cylinder piston is also pushed forward accordingly. At this time, it is considered that the servo cylinder piston has not touched the top.

[0100] Optionally, Figure 5 A flow chart of a touch-to-top degradation control mode provided by an embodiment of the present invention, Figure 6 A timing diagram of the top-down degradation control mode provided by an embodiment of the present invention, referring to Figure 2, Figure 5 and Figure 6 In step 11, the top-down control mode is specifically as follows: step 110, collecting the initial value of the servo cylinder pressure sensor P2; step 111, closing the servo cylinder circuit isolation valve; step 112, controlling the servo motor to reverse, driving the transmission mechanism to drive the servo cylinder piston to retreat the stroke s; step 113, controlling the servo motor to rotate forward, driving the transmission mechanism to drive the servo cylinder piston forward, and at the same time detecting the measured value of the servo cylinder pressure sensor P2. When the measured value of the servo cylinder pressure sensor P2 reaches the initial value, the servo cylinder circuit isolation valve is opened.

[0101] Specifically, refer to Figure 5 , when the vehicle speed is low, if the servo cylinder piston touches the top, such as Figure 6 At the moments t2 and t6 in the DBS top-out degradation control mode, it is necessary to enter the DBS top-out degradation control mode. When executing the top-out degradation control mode, firstly, step 110 is performed to collect the initial value of the servo cylinder pressure sensor P2. The initial value refers to the value of the servo cylinder pressure sensor P2 at the current moment. After obtaining the initial value, in step 111, the servo cylinder circuit isolation valve is immediately closed to ensure that the pressure built up by the servo cylinder piston this time is maintained behind the servo cylinder circuit isolation valve, and the pressure built up this time will not be released when the servo motor retreats, such as Figure 6 The moments t2 and t6 in the graph.

[0102] Then, in step 112, the servo motor is controlled to reverse, and the transmission mechanism is driven to drive the servo cylinder piston to retreat by a stroke s. Figure 6 During the t2-t3 and t6-t7 time periods, during the retraction of the servo cylinder piston, the pressure in the servo cylinder body gradually decreases to 0, the main leather cup of the servo cylinder piston relaxes, negative pressure is generated in the servo cylinder body, and the brake fluid flows from the loop connected to the reservoir through the gap between the servo cylinder piston and the main leather cup of the servo cylinder to replenish the servo cylinder body, completing the fluid replenishment.

[0103] After the servo cylinder piston retreats for s stroke, the current fluid replenishment is completed. At this time, step 113 is performed to control the servo motor to rotate forward, drive the transmission mechanism to drive the servo cylinder piston forward, and then the servo cylinder piston is retracted. Figure 6 During the forward push, the value of the servo cylinder pressure sensor P2 is detected at the same time. When the value of the servo cylinder pressure sensor P2 reaches the initial value again, the servo cylinder circuit isolation valve is powered on, such as Figure 6 At the moments t4 and t8 in the figure, the servo cylinder piston can be pushed forward to compress more brake fluid to build pressure until the target pressure is reached. Figure 6 T9 and later.

[0104] When the servo cylinder piston touches the top, this control method can be used to achieve the specified target braking pressure requirement and achieve sufficient braking force output.

[0105] It should be noted that prematurely opening the servo cylinder circuit isolation valve will cause the pressure maintained after the servo cylinder circuit isolation valve to be released, causing the control effect to deteriorate; and because the servo cylinder circuit isolation valve is a normally closed valve, the circuit is arranged in a bottom-in and side-out manner. If the pressure at the rear end is too high, that is, the pressure difference on both sides of the valve is too large, the valve cannot be opened with a normal current control, resulting in the failure to execute the designed control strategy. Therefore, in step 113 of this embodiment, the servo motor is first controlled to rotate forward to push the servo cylinder piston forward, and the servo cylinder circuit isolation valve is opened only after the value of the servo cylinder pressure sensor P2 reaches the initial value again.

[0106] Optionally, Figure 7 Another flow chart of the piston top contact processing method provided by the embodiment of the present invention is shown in FIG. Figure 7 Before entering the ESC brake compensation mode, the method further includes: step 91, detecting whether the ESC supports brake compensation, if not, entering the top-out degradation control mode; if yes, entering the ESC brake compensation mode.

[0107] Specifically, refer to Figure 7 When the vehicle is in a dynamic driving state, the fully decoupled brake-by-wire system enters the ESC brake compensation mode, but when the ESC does not support brake compensation, the program cannot be executed normally. Therefore, in order to ensure the normal execution of the program, this embodiment detects the ESC through step 91 before entering the ESC brake compensation mode to determine whether the ESC supports brake compensation. When brake compensation is not supported, the top-out degradation control mode is entered to achieve step-by-step pressure buildup to ensure sufficient braking force output. When brake compensation is supported, the ESC brake compensation mode is entered, and the brake fluid is extracted from the circuits corresponding to the two one-way valves to actively build pressure, thereby achieving auxiliary pressure buildup for the fully decoupled brake-by-wire system.

[0108] Here, whether hydraulic brake compensation is supported can be determined by detecting the flag of ESC feedback. For example, when the HBC_Available flag of ESC is False, it means that brake compensation is not currently supported. Otherwise, it means that brake compensation is supported.

[0109] Based on the same inventive concept, the present invention also provides a fully decoupled brake-by-wire system piston top-contact processing system. Figure 8 A schematic diagram of a piston top contact processing system provided by an embodiment of the present invention, referring to Figure 1 and Figure 8 The fully decoupled brake-by-wire system piston top-contact processing system 100 provided by the embodiment of the present invention comprises:

[0110] A judgment module 101 is used to judge whether the fully decoupled brake-by-wire system is powered on normally;

[0111] The control module 102 is used for controlling the full decoupled wire control brake system to enter the mechanical backup brake mode when the system is not powered on normally, and the program ends;

[0112] The detection module 103 is used to detect whether the fully decoupled brake-by-wire system has a fault when the fully decoupled brake-by-wire system is powered on normally;

[0113] When there is a fault in the fully decoupled brake-by-wire system, the control module 102 is further used to control the entry into the mechanical backup braking mode and determine whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether there is a fault in the fully decoupled brake-by-wire system.

[0114] When there is no fault in the fully decoupled brake-by-wire system, the detection module 103 is further used to detect whether the fully decoupled brake-by-wire system is in a braking state;

[0115] When the fully decoupled brake-by-wire system is not in a braking state, the control module 102 is also used to control the entry into the normal brake-by-wire mode and determine whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault.

[0116] When the fully decoupled brake-by-wire system is in a braking state, the judgment module 101 is also used to judge whether the servo cylinder piston has touched the top;

[0117] If the servo cylinder piston does not touch the top, the control module 102 is also used to control the entry into the normal wire control brake mode and determine whether the power is off. If so, the program ends; if not, jump to the step of detecting whether there is a fault in the fully decoupled wire control brake system;

[0118] The reporting module is used to report an abnormality when the servo cylinder piston touches the top;

[0119] The judging module is used to judge whether the vehicle speed is less than a first threshold;

[0120] When the vehicle speed is greater than the first threshold, the control module 102 is further used to control the entry into the ESC brake compensation mode and determine whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system;

[0121] When the vehicle speed is less than or equal to the first threshold, the control module 102 is also used to control the entry into the top-out degradation control mode and determine whether the power is turned off. If so, the program ends; if not, it jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system.

[0122] Specifically, refer to Figure 8In the fully decoupled brake-by-wire system piston top-touching processing system provided by the embodiment of the present invention, after the DBS is powered on, all the solenoid valves are powered on and work. In order to ensure that they can work normally, firstly, the judgment module 101 is used to judge whether the fully decoupled brake-by-wire system is powered on normally.

[0123] When the fully decoupled brake-by-wire system is not powered on normally, the control module 102 is used to make the fully decoupled brake-by-wire system enter the mechanical backup braking mode. At this time, since the fully decoupled brake-by-wire system is not powered on normally, this step does not involve any control strategy and the program ends directly.

[0124] When the fully decoupled brake-by-wire system is powered on normally, it is necessary to determine whether the fully decoupled brake-by-wire system has a fault. Therefore, this embodiment detects whether the fully decoupled brake-by-wire system has a fault through the detection module 103. Here, the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve in the fully decoupled brake-by-wire system can be detected respectively. When any one of them fails, it is considered that the fully decoupled brake-by-wire system has a fault.

[0125] When the fully decoupled brake-by-wire system fails, it cannot work normally. Therefore, in this embodiment, the fully decoupled brake-by-wire system enters the mechanical backup braking mode through the control module 102. After entering the mechanical backup braking mode, the motor and all the solenoid valves are not controlled. It is determined whether to power it off. If it is powered off, the program ends; if it is not powered off, the fully decoupled brake-by-wire system is checked again to see if it has a fault, and subsequent operations are performed.

[0126] When the fully decoupled brake-by-wire system has no faults, it indicates that it can work normally. At this time, it is necessary to determine whether it is currently in a braking state. Therefore, in this embodiment, the detection module 103 detects whether the fully decoupled brake-by-wire system is in a braking state.

[0127] When the fully decoupled brake-by-wire system is not in a braking state, there is no problem of insufficient braking force during braking. Therefore, in this embodiment, the fully decoupled brake-by-wire system enters a normal brake-by-wire mode through the control module 102, at which time there is no brake pressure target. Here, since the fully decoupled brake-by-wire system is in a normal power-on state, in this step, it is determined whether to power it off. If it is powered off, the program ends; if it is not powered off, the fully decoupled brake-by-wire system is checked again to see if there is a fault, and subsequent operations are performed.

[0128] When the fully decoupled brake-by-wire system is in a braking state, it is necessary to determine the current position state of the servo cylinder piston. Therefore, in this embodiment, the determination module 101 determines whether the servo cylinder piston has touched the top. The top contact check can be determined by comprehensively analyzing the relationship between the servo cylinder piston stroke, the actual torque of the motor, the actual torque change rate of the motor, the actual speed of the motor and other signals.

[0129] If the servo cylinder piston does not touch the top, the servo cylinder piston can continue to be pushed forward to build pressure. Therefore, when the servo cylinder piston does not touch the top, this embodiment uses the control module 102 to make the fully decoupled brake-by-wire system enter the normal brake-by-wire mode. At this time, since the fully decoupled brake-by-wire system is in a braking state, after entering the normal brake-by-wire mode, the fully decoupled brake-by-wire system will normally build pressure according to the target braking pressure. In this step, it is determined whether to power it off. If it is powered off, the program ends; if it is not powered off, the fully decoupled brake-by-wire system is checked again to see if there is a fault, and subsequent operations are performed.

[0130] refer to Figure 3 If the servo cylinder piston touches the top, even if the servo motor output torque continues to increase, the servo cylinder piston stroke will not increase. At this time, the servo cylinder piston may not have enough pressure-building stroke, which may result in failure to build the corresponding target pressure. Therefore, when the servo cylinder piston touches the top, the present embodiment reports related work abnormalities through the reporting module, prompting the driver that a fault has occurred, saving the driver's reaction time, so that the driver can take deceleration and stop measures such as parking brakes earlier.

[0131] In this embodiment, while reporting the abnormality, the judgment module 101 compares the vehicle speed with the first threshold to determine the execution action after the top is touched. Here, the first threshold can be, for example, 1 km / h, which can be set according to actual conditions and is not specifically limited here.

[0132] When the vehicle speed is greater than the first threshold value, assuming that the first threshold value is 1km / h, then when the vehicle speed is greater than 1km / h, it means that the vehicle is currently in a dynamic driving state. Since the pressure at the wheel end will be maintained instead of continuing to increase during the period when the servo cylinder circuit isolation valve is closed and the motor is retreated to replenish fluid. Therefore, when the vehicle is in a dynamic driving state, this implementation uses the control module 102 to make the fully decoupled wire control brake system enter the ESC brake compensation mode, and actively builds pressure by extracting brake fluid from the corresponding circuits of the two one-way valves of the fully decoupled wire control brake system, thereby realizing auxiliary pressure building for the fully decoupled wire control brake system. In this step, it is also determined whether to power it off. If it is powered off, the program ends; if it is not powered off, the fully decoupled wire control brake system is checked again to see if there is a fault, and subsequent operations are performed.

[0133] When the vehicle speed is less than or equal to the first threshold, assuming that the first threshold is 1km / h, then when the vehicle speed is less than or equal to 1km / h, it indicates that the vehicle is currently in a nearly stationary state. At this time, since the pressure has not reached the target brake pressure, the present embodiment uses the control module 102 to make the fully decoupled brake-by-wire system enter the top-out degradation control mode, and compresses more brake fluid to build pressure by controlling the servo cylinder to retract and replenish fluid and then push forward, thereby reaching the target brake pressure. In this step, it is also determined whether to power off the system. If it is powered off, the program ends; if it is not powered off, the fully decoupled brake-by-wire system is checked again to see if there is a fault, and subsequent operations are performed.

[0134] The fully decoupled brake-by-wire system piston top-touching processing system provided in the embodiment of the present invention aims to solve the problem that the fully decoupled brake-by-wire system may not be able to further increase the braking force output after the servo cylinder piston touches the top during braking. Different braking control methods are proposed according to the vehicle speed, thereby improving the safety of static and dynamic braking driving. When the vehicle is close to a standstill, the top-touching degradation control is performed through the coordination of the solenoid valve and the servo motor to achieve a relay and step-by-step increase in the braking pressure, which can avoid the ESC braking compensation action while meeting the braking demand, thereby helping to reduce the complexity of the system. In addition, when the servo cylinder piston touches the top, the present invention notifies the driver of a fault by reporting an abnormality, thereby saving the driver's reaction time and allowing the driver to take deceleration measures such as parking brakes earlier.

[0135] Optionally, refer to Figure 8 When judging whether the servo cylinder piston has touched the top, the judgment module 101 is specifically used for: when the change of the servo motor torque output value exceeds the second threshold value, and the servo cylinder piston stroke remains unchanged, it indicates that the servo cylinder piston has touched the top; conversely, when the servo cylinder piston stroke changes with the change of the servo motor torque output value, it indicates that the servo cylinder piston has not touched the top.

[0136] Specifically, refer to Figure 8 The top contact check can be judged by comprehensively analyzing the relationship between the servo cylinder piston stroke, the actual motor torque, the actual motor torque change rate, the actual motor speed and other signals.

[0137] According to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is determined whether the servo cylinder piston has reached the top. Figure 4 When it is detected that the servo cylinder piston stroke no longer increases, but the servo motor torque output value still increases, and the increase exceeds a certain threshold, it is determined that the servo cylinder piston has touched the top. Here, the threshold is set to the second threshold, and the specific value of the second threshold can be set according to actual conditions and is not specifically limited here.

[0138] Continue to refer Figure 4When the servo cylinder piston does not touch the top, as the servo motor torque increases, the servo cylinder piston is also pushed forward accordingly. At this time, it is considered that the servo cylinder piston has not touched the top.

[0139] Optionally, Fig. 9 Another structural schematic diagram of the piston top contact processing system provided by the embodiment of the present invention is shown in FIG. Fig. 9 , when executing the top-out degradation control mode, it also includes:

[0140] The acquisition module 104 is used to acquire the initial value of the servo cylinder pressure sensor P2;

[0141] Closing module 105, used to close the servo cylinder circuit isolation valve;

[0142] The driving module 106 is used to control the servo motor to reverse and drive the transmission mechanism to drive the servo cylinder piston to retreat by a stroke s;

[0143] The drive module 106 is also used to control the forward rotation of the servo motor, drive the transmission mechanism to drive the servo cylinder piston forward, and at the same time detect the measurement value of the servo cylinder pressure sensor P2. When the measurement value of the servo cylinder pressure sensor P2 reaches the initial value, the servo cylinder circuit isolation valve is opened.

[0144] Specifically, refer to Fig. 9 , when the vehicle speed is low, if the servo cylinder piston touches the top, such as Figure 6 At the moments t2 and t6 in the DBS top-out degradation control mode, it is necessary to enter the DBS top-out degradation control mode. When executing the top-out degradation control mode, the initial value of the servo cylinder pressure sensor P2 is first collected by the acquisition module 104. The initial value refers to the value of the servo cylinder pressure sensor P2 at the current moment. After obtaining the initial value, the closing module 105 immediately closes the servo cylinder circuit isolation valve to ensure that the pressure built up by the servo cylinder piston this time is maintained behind the servo cylinder circuit isolation valve, and the pressure built up this time will not be released when the servo motor retreats, such as Figure 6 The moments t2 and t6 in the graph.

[0145] Then, the driving module 106 is used to control the servo motor to reverse, and the transmission mechanism is driven to drive the servo cylinder piston to retreat by a stroke s. Figure 6 During the t2-t3 and t6-t7 time periods, during the retraction of the servo cylinder piston, the pressure in the servo cylinder body gradually decreases to 0, the main leather cup of the servo cylinder piston relaxes, negative pressure is generated in the servo cylinder body, and the brake fluid flows from the loop connected to the reservoir through the gap between the servo cylinder piston and the main leather cup of the servo cylinder to replenish the servo cylinder body, completing the fluid replenishment.

[0146] After the servo cylinder piston retreats for s stroke, the current fluid replenishment is completed. At this time, the drive module 106 controls the servo motor to rotate forward, and the drive transmission mechanism drives the servo cylinder piston to push forward. Figure 6During the forward push, the value of the servo cylinder pressure sensor P2 is detected at the same time. When the value of the servo cylinder pressure sensor P2 reaches the initial value again, the servo cylinder circuit isolation valve is powered on, such as Figure 6 At the moments t4 and t8 in the figure, the servo cylinder piston can be pushed forward to compress more brake fluid to build pressure until the target pressure is reached. Figure 6 T9 and later.

[0147] When the servo cylinder piston touches the top, this control method can be used to achieve the specified target braking pressure requirement and achieve sufficient braking force output.

[0148] It should be noted that prematurely opening the servo cylinder circuit isolation valve will cause the pressure maintained after the servo cylinder circuit isolation valve to be released, causing the control effect to deteriorate; and because the servo cylinder circuit isolation valve is a normally closed valve, the circuit is arranged in a bottom-in and side-out manner. If the pressure at the rear end is too high, that is, the pressure difference on both sides of the valve is too large, the valve cannot be opened with a normal current control, resulting in the inability to execute the designed control strategy. Therefore, this embodiment first controls the servo motor to rotate forward to push the servo cylinder piston forward, and only opens the servo cylinder circuit isolation valve after the value of the servo cylinder pressure sensor P2 reaches the initial value again.

[0149] Optionally, the detection module 103 is further configured to detect whether the ESC supports brake compensation before entering the ESC brake compensation mode, and if not, enter the top-out degradation control mode; if so, enter the ESC brake compensation mode.

[0150] Specifically, refer to Figure 8 When the vehicle is in a dynamic driving state, the fully decoupled brake-by-wire system enters the ESC brake compensation mode, but when the ESC does not support brake compensation, the program cannot be executed normally. Therefore, in order to ensure the normal execution of the program, this embodiment detects the ESC through the detection module 103 before entering the ESC brake compensation mode to determine whether the ESC supports brake compensation. When brake compensation is not supported, the top-out degradation control mode is entered to achieve step-by-step pressure buildup to ensure sufficient braking force output; when brake compensation is supported, the ESC brake compensation mode is entered, and brake fluid is extracted through two one-way valves to actively build pressure, thereby achieving auxiliary pressure buildup for the fully decoupled brake-by-wire system.

[0151] Here, whether hydraulic brake compensation is supported can be determined by detecting the flag of ESC feedback. For example, when the HBC_Available flag of ESC is False, it means that brake compensation is not currently supported. Otherwise, it means that brake compensation is supported.

[0152] Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0153] Those skilled in the art can understand that the modules in the device in the embodiment can be distributed in the device in the embodiment according to the description of the embodiment, or can be changed accordingly and located in one or more devices different from the embodiment. The modules in the above embodiment can be combined into one module, or can be further divided into multiple sub-modules.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for processing piston top contact in a fully decoupled wire-controlled brake system, characterized in that: include: Determine whether the fully decoupled brake-by-wire system is powered on normally; When the fully decoupled brake-by-wire system is not powered on normally, it enters the mechanical backup brake mode and the program ends; When the fully decoupled brake-by-wire system is powered on normally, detecting whether the fully decoupled brake-by-wire system has a fault; When a fault occurs in the fully decoupled brake-by-wire system, the system enters the mechanical backup brake mode and determines whether the power is off. If so, the program ends. If not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault. When there is no fault in the fully decoupled brake-by-wire system, detecting whether the fully decoupled brake-by-wire system is in a braking state; When the fully decoupled brake-by-wire system is not in a braking state, the normal brake-by-wire mode is entered, and it is determined whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault; When the fully decoupled brake-by-wire system is in the braking state, determine whether the servo cylinder piston has touched the top; If the servo cylinder piston does not touch the top, the normal brake-by-wire mode is entered, and it is determined whether the power is off. If so, the program ends. If not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault. If the servo cylinder piston touches the top, an abnormality is reported and it is determined whether the vehicle speed is less than a first threshold; When the vehicle speed is greater than the first threshold, the ESC brake compensation mode is entered, and the brake fluid is extracted from the corresponding circuits of the two one-way valves of the fully decoupled wire-controlled brake system to actively build pressure and determine whether the power is off. If so, the program ends, and if not, jumps to the step of detecting whether the fully decoupled wire-controlled brake system has a fault; When the vehicle speed is less than or equal to the first threshold, the top-out degradation control mode is entered. By controlling the servo cylinder to retreat and replenish fluid and then push forward, more brake fluid is compressed to build pressure, and it is determined whether the power is off. If so, the program ends. If not, it jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system.

2. The method for processing piston top contact of a fully decoupled brake-by-wire system according to claim 1, characterized in that: Detecting whether the fully decoupled brake-by-wire system has a fault is specifically as follows: Check whether the servo motor, manual cylinder circuit isolation valve, and servo cylinder circuit isolation valve are faulty.

3. The method for processing piston top contact of a fully decoupled brake-by-wire system according to claim 1, characterized in that: Determine whether the servo cylinder piston has touched the top, specifically: According to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is judged whether the servo cylinder piston has touched the top: when the change of the servo motor torque output value exceeds the second threshold value and the servo cylinder piston stroke remains unchanged, it indicates that the servo cylinder piston has touched the top; conversely, when the servo cylinder piston stroke changes with the change of the servo motor torque output value, it indicates that the servo cylinder piston has not touched the top.

4. The method for processing piston top contact of a fully decoupled brake-by-wire system according to claim 1, characterized in that: The top-out degradation control mode is specifically: Collect the initial value of the servo cylinder pressure sensor P2; Close the servo cylinder circuit isolation valve; Control the servo motor to reverse, drive the transmission mechanism to drive the servo cylinder piston to retreat by a stroke s; The servo motor is controlled to rotate forward, and the transmission mechanism is driven to push the servo cylinder piston forward. At the same time, the measured value of the servo cylinder pressure sensor P2 is detected. When the measured value of the servo cylinder pressure sensor P2 reaches the initial value, the servo cylinder circuit isolation valve is opened.

5. The method for processing piston top contact of a fully decoupled brake-by-wire system according to claim 1, characterized in that: Before entering the ESC brake compensation mode, it also includes: Check whether ESC supports brake compensation. If not, enter the top-out degradation control mode; if yes, enter the ESC brake compensation mode.

6. A fully decoupled brake-by-wire system piston top-contact processing system, characterized in that: include: A judgment module, used to judge whether the fully decoupled brake-by-wire system is powered on normally; A control module, used for controlling the full decoupled brake-by-wire system to enter a mechanical backup braking mode when the system is not powered on normally, and the program ends; A detection module, used for detecting whether the fully decoupled brake-by-wire system has a fault when the fully decoupled brake-by-wire system is normally powered on; When a fault occurs in the fully decoupled brake-by-wire system, the control module is further used to control the entry into the mechanical backup braking mode and determine whether the power is turned off. If so, the program ends; if not, the program jumps to the step of detecting whether a fault occurs in the fully decoupled brake-by-wire system. When there is no fault in the fully decoupled brake-by-wire system, the detection module is further used to detect whether the fully decoupled brake-by-wire system is in a braking state; When the fully decoupled brake-by-wire system is not in a braking state, the control module is further used to control the entry into a normal brake-by-wire mode and determine whether the power is off. If so, the program ends; if not, the program jumps to the step of detecting whether the fully decoupled brake-by-wire system has a fault; When the fully decoupled brake-by-wire system is in a braking state, the judgment module is also used to judge whether the servo cylinder piston has touched the top; If the servo cylinder piston does not touch the top, the control module is also used to control the entry into the normal wire control brake mode and determine whether the power is off. If so, the program ends; if not, jump to the step of detecting whether the fully decoupled wire control brake system has a fault; The reporting module is used to report an abnormality when the servo cylinder piston touches the top; The judging module is used to judge whether the vehicle speed is less than a first threshold; When the vehicle speed is greater than the first threshold, the control module is further used to control the entry into the ESC brake compensation mode, by extracting brake fluid from the corresponding circuits of the two one-way valves of the fully decoupled wire control brake system, actively building up pressure, and determining whether the power is off, if so, the program ends; if not, jumps to the step of detecting whether the fully decoupled wire control brake system has a fault; When the vehicle speed is less than or equal to the first threshold, the control module is also used to control the entry into the top-out degradation control mode, by controlling the servo cylinder to retreat and replenish fluid and then push forward, compressing more brake fluid to build pressure, and determining whether the power is off. If so, the program ends; if not, jumps to the step of detecting whether there is a fault in the fully decoupled wire control brake system.

7. The piston top-contact processing system of the fully decoupled brake-by-wire system according to claim 6, characterized in that: When detecting whether the fully decoupled brake-by-wire system has a fault, the detection module is specifically used to: Check whether the servo motor, manual cylinder circuit isolation valve, and servo cylinder circuit isolation valve are faulty.

8. The piston top-contact processing system of the fully decoupled brake-by-wire system according to claim 6, characterized in that: When judging whether the servo cylinder piston has touched the top, the judging module is specifically used for: According to the relationship between the servo cylinder piston stroke and the servo motor torque output value, it is judged whether the servo cylinder piston has touched the top: when the change of the servo motor torque output value exceeds the second threshold value and the servo cylinder piston stroke remains unchanged, it indicates that the servo cylinder piston has touched the top; conversely, when the servo cylinder piston stroke changes with the change of the servo motor torque output value, it indicates that the servo cylinder piston has not touched the top.

9. The fully decoupled brake-by-wire system piston top-out processing system according to claim 6, characterized in that: When executing the top-out degradation control mode, the method further includes: The acquisition module is used to acquire the initial value of the servo cylinder pressure sensor P2; A closing module, used to close the servo cylinder circuit isolation valve; A driving module, used to control the servo motor to reverse and drive the transmission mechanism to drive the servo cylinder piston to retreat by a stroke s; The driving module is also used to control the forward rotation of the servo motor, drive the transmission mechanism to push the servo cylinder piston forward, and simultaneously detect the measurement value of the servo cylinder pressure sensor P2. When the measurement value of the servo cylinder pressure sensor P2 reaches the initial value, the servo cylinder circuit isolation valve is opened.

10. The piston top-out processing system of the fully decoupled brake-by-wire system according to claim 6, characterized in that: The detection module is also used to detect whether the ESC supports brake compensation before entering the ESC brake compensation mode. If not, enter the top-out degradation control mode; if so, enter the ESC brake compensation mode.

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