Fully decoupled brake-by-wire method and system

Abstract

This application relates to a fully decoupled brake-by-wire method and system, applicable to the brake-by-wire technology field. The method includes: when the brake-by-wire system is normally powered on, detecting whether it has a fault; if so, entering a mechanical backup braking mode; if not, detecting whether it is in a pedal-powered state; if not, entering a normal brake-by-wire mode; if in a pedal-powered state, determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold; if not, entering a normal brake-by-wire mode; if greater than the first pressure threshold, entering a pedal-powered braking mode, determining a target brake pressure based on the stroke of the mechanical push rod and the pressure detected by the manual cylinder pressure sensor; if the brake-by-wire system is not powered off, returning to detecting whether the brake-by-wire system has a fault; if powered off, terminating the process. This application ensures output brake pressure while also taking into account brake pedal feel.

Description

Technical Field

[0001] The present application relates to the technical field of wire-controlled braking, and in particular to a fully decoupled wire-controlled braking method and system. Background Art

[0002] In vehicles equipped with a brake-by-wire system, when the driver presses the brake pedal and powers on, the brake-by-wire system switches from mechanical backup braking mode to normal brake-by-wire mode. For a fully decoupled brake-by-wire system, if normal brake-by-wire mode is entered directly upon pressing the brake pedal and powering on, the simulated cylinder circuit isolation valve, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve will be energized. Because the simulated cylinder is pressure-free before the simulated cylinder circuit isolation valve opens, while the manual cylinder chamber contains hydraulic pressure, a significant portion of the fluid volume in the manual cylinder chamber is transferred to the simulated cylinder at the moment the simulated cylinder circuit isolation valve opens to balance the hydraulic pressure. This can cause the brake pedal to momentarily sink. Furthermore, the deeper the brake pedal is pressed when power is applied, the more pronounced the sinking, and the worse the brake pedal feel for the driver. Summary of the Invention

[0003] In order to solve the above technical problems, the present application provides a fully decoupled wire-controlled braking method, system and storage medium.

[0004] According to a first aspect of the present application, a fully decoupled brake-by-wire method is provided, which is applied to a brake-by-wire system. The method comprises:

[0005] Check whether the brake-by-wire system is powered on normally;

[0006] If the wire control brake system is not powered on normally, the system enters the mechanical backup brake mode;

[0007] If the brake-by-wire system is powered on normally, detecting whether the brake-by-wire system has a fault;

[0008] If there is a fault in the brake-by-wire system, a mechanical backup braking mode is entered;

[0009] If there is no fault in the brake-by-wire system, detecting whether the brake-by-wire system is in a pedal-powered state;

[0010] If the brake-by-wire system is not in the pedal-powered state, the normal brake-by-wire mode is entered;

[0011] If the brake-by-wire system is in a pedal-powered state, determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold;

[0012] If the pressure in the manual cylinder is less than or equal to a first pressure threshold, the normal brake-by-wire mode is entered;

[0013] If the pressure in the manual cylinder is greater than a first pressure threshold, entering a pedal-operated electric braking mode;

[0014] In the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after power is applied. A first target brake pressure is determined according to the stroke of the mechanical push rod; a second target brake pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target brake pressure and the second target brake pressure is selected as the target brake pressure, and the brake pressure is output;

[0015] detecting whether the brake-by-wire system is powered off;

[0016] If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault;

[0017] If it is detected that the brake-by-wire system is powered off, the process ends.

[0018] Optionally, before determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold, the method further includes:

[0019] If the brake-by-wire system is in a pedal-powered state, a signal check is performed on the pressure sensor of the electronic stability control system itself to determine whether the first pressure measurement value is valid; a signal check is performed on the pressure sensor of the manual cylinder to determine whether the second pressure measurement value is valid;

[0020] If the first pressure measurement value is invalid, setting the first pressure measurement value to 0;

[0021] If the second pressure measurement is invalid, the mechanical backup braking mode is entered;

[0022] If both the first pressure measurement value and the second pressure measurement value are valid, determining whether there is an abnormality in the pressure within the brake-by-wire system by comparing the first pressure measurement value measured by the pressure sensor of the electronic stability control system itself with the second pressure measurement value measured by the manual cylinder pressure sensor;

[0023] If there is no abnormality in the pressure in the brake-by-wire system, executing the step of determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold;

[0024] If there is an abnormality in the pressure of the wire control brake system, the mechanical backup braking mode is entered.

[0025] Optionally, the method further includes:

[0026] When the wire control brake system is in the pedal-operated electric braking mode, the pressure in the manual cylinder is detected. If the pressure in the manual cylinder is less than a second pressure threshold, the normal wire control brake mode is entered, wherein the first pressure threshold is greater than the second pressure threshold.

[0027] Optionally, before detecting whether the brake-by-wire system is in a pedaling power-on state, the method further includes:

[0028] If the vehicle is equipped with an electronic parking brake system, check whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched since power was applied;

[0029] If the electronic parking brake system is in the unapplied state, or the electronic parking brake system is in the applied state and its state has been switched, then executing the step of detecting whether the brake-by-wire system is in the pedal-on state;

[0030] If the electronic parking brake system is in the applied state and its state has not been switched before, it enters the mechanical backup brake mode.

[0031] Optionally, the method further includes:

[0032] If vehicle slippage is detected in the pedal-operated power-on braking mode, the target brake pressure is increased according to a set increase gradient based on the vehicle slippage state, wherein the increased target brake pressure is not greater than the maximum allowable operating pressure of the brake-by-wire system;

[0033] After detecting that the vehicle has stopped slipping, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is stationary before slipping, the increased target brake pressure will be reduced to the maximum brake pressure limit value according to the set descent gradient, and the normal wire control braking mode will be entered when the pressure in the manual cylinder is less than the second pressure threshold.

[0034] Optionally, comparing the first pressure measurement value and the second pressure measurement value to determine whether there is an abnormality in the pressure within the brake-by-wire system includes:

[0035] If the absolute value of the difference between the first pressure measurement value and the second pressure measurement value is less than or equal to a pressure difference threshold, determining that there is no abnormality in the pressure in the brake-by-wire system;

[0036] If a difference between the first pressure measurement value and the second pressure measurement value is greater than a pressure difference threshold, determining that a pressure abnormality exists in the brake-by-wire system;

[0037] If the difference between the second pressure measurement and the first pressure measurement is greater than a pressure difference threshold, it is determined that there is no abnormality in the pressure within the brake-by-wire system.

[0038] Optionally, detecting whether the brake-by-wire system is in a pedal-powered state includes:

[0039] If it is detected at the moment of power-on that the brake pedal is depressed, it is determined that the brake-by-wire system is in a pedal-depressed power-on state;

[0040] When the brake-by-wire system is in a pedal-on state, the brake-by-wire system exits the pedal-on state only after detecting that the brake pedal is fully released.

[0041] If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

[0042] Optionally, after entering the mechanical backup braking mode, the method further includes:

[0043] Control the manual cylinder circuit isolation valve to remain in the open state, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain in the closed state, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side brake circuit. When the brake pedal is stepped on to build up pressure, the connected brake circuit pressure is built up normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0044] Optionally, after entering the normal brake-by-wire mode, the method further includes:

[0045] The manual cylinder circuit isolation valve is controlled to change from an open state to a closed state, and the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are controlled to change from a closed state to an open state, and the pressure in the manual cylinder and the simulation cylinder is measured by the manual cylinder pressure sensor, and the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side are measured by the servo cylinder pressure sensor.

[0046] According to a second aspect of the present application, a fully decoupled brake-by-wire system is provided, comprising: a controller, a brake pedal, a mechanical push rod, a travel sensor, a fluid reservoir, a manual cylinder including a piston and a spring, a manual cylinder pressure sensor, a manual cylinder circuit isolation valve, a simulation cylinder circuit isolation valve, a simulation cylinder, a servo cylinder circuit isolation valve, a servo cylinder pressure sensor, a servo cylinder body, a servo cylinder piston, a ball screw transmission mechanism, and a servo motor;

[0047] The controller is configured to detect whether the brake-by-wire system is powered on normally; if the brake-by-wire system is not powered on normally, enter a mechanical backup braking mode; if the brake-by-wire system is powered on normally, detect whether the brake-by-wire system has a fault; if the brake-by-wire system has a fault, enter a mechanical backup braking mode; if the brake-by-wire system has no fault, detect whether the brake-by-wire system is in a pedal-powered state; and,

[0048] If the brake-by-wire system is not in the pedal-powered state, it enters the normal brake-by-wire mode; if the brake-by-wire system is in the pedal-powered state, it determines whether the pressure in the manual cylinder at the moment of power-on is greater than the first pressure threshold; if the pressure in the manual cylinder is less than or equal to the first pressure threshold, it enters the normal brake-by-wire mode; if the pressure in the manual cylinder is greater than the first pressure threshold, it enters the pedal-powered braking mode; in the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after power is supplied, and the first target braking pressure is determined according to the stroke of the mechanical push rod; the second target braking pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target braking pressure and the second target braking pressure is selected as the target braking pressure, and the braking pressure is output;

[0049] detecting whether the brake-by-wire system is powered off;

[0050] If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault;

[0051] If it is detected that the brake-by-wire system is powered off, the process ends.

[0052] Optionally, the controller is also used for comparing and verifying the pressure signal measurement values ​​and judging the entry into related modes, that is, when the wire control brake system is in the pedal-powered state, before judging whether the pressure in the manual cylinder at the moment of power-on is greater than the first pressure threshold, the signal of the pressure sensor of the electronic stability control system itself is first verified to determine whether the first pressure measurement value is valid; the signal of the manual cylinder pressure sensor is verified to determine whether the second pressure measurement value is valid; if the first pressure measurement value is invalid, the first pressure measurement value is set to 0; if the second pressure measurement value is invalid, the mechanical backup braking mode is entered; if both the first pressure measurement value and the second pressure measurement value are valid, the first pressure measurement value measured by the pressure sensor of the electronic stability control system itself and the second pressure measurement value measured by the manual cylinder pressure sensor are compared to determine whether there is an abnormality in the pressure in the wire control brake system; if there is no abnormality in the pressure in the wire control brake system, the step of judging whether the pressure in the manual cylinder at the moment of power-on is greater than the first pressure threshold is executed; if there is an abnormality in the pressure in the wire control brake system, the mechanical backup braking mode is entered.

[0053] Optionally, the controller is also used to detect the pressure in the manual cylinder when the wire control braking system is in the pedal-operated electric braking mode, and enter the normal wire control braking mode if the pressure in the manual cylinder is less than a second pressure threshold, wherein the first pressure threshold is greater than the second pressure threshold.

[0054] Optionally, the controller is further used to, before detecting whether the brake-by-wire system is in the pedal-powered state, if the vehicle is equipped with an electronic parking brake system, detect whether the electronic parking brake system is in the pulled-up state and whether its state has never been switched after power-on; if the electronic parking brake system is in the unpulled state, or the electronic parking brake system is in the pulled-up state and its state has ever been switched, execute the step of detecting whether the brake-by-wire system is in the pedal-powered state; if the electronic parking brake system is in the pulled-up state and its state has ever been switched, enter the mechanical backup braking mode.

[0055] Optionally, the controller is also used to increase the target brake pressure according to a set increasing gradient based on the slipping state if slipping is detected in the pedal-operated electric braking mode, wherein the increased target brake pressure is not greater than the maximum allowable working pressure of the wire control brake system; after detecting that the slipping has stopped, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is in a stationary state before slipping, the increased target brake pressure is reduced to the maximum brake pressure limit value according to a set decreasing gradient, and when the pressure in the manual cylinder is less than a second pressure threshold, the normal wire control brake mode is entered.

[0056] Optionally, the controller is specifically configured to determine whether there is an abnormality in the pressure in the brake-by-wire system by performing the following steps:

[0057] If the absolute value of the difference between the first pressure measurement value and the second pressure measurement value is less than or equal to a pressure difference threshold, determining that there is no abnormality in the pressure in the brake-by-wire system;

[0058] If a difference between the first pressure measurement value and the second pressure measurement value is greater than a pressure difference threshold, determining that a pressure abnormality exists in the brake-by-wire system;

[0059] If the difference between the second pressure measurement and the first pressure measurement is greater than a pressure difference threshold, it is determined that there is no abnormality in the pressure within the brake-by-wire system.

[0060] Optionally, the controller is specifically configured to detect whether the brake-by-wire system is in a pedal-powered state by performing the following steps:

[0061] If it is detected at the moment of power-on that the brake pedal is depressed, it is determined that the brake-by-wire system is in a pedal-depressed power-on state;

[0062] When the brake-by-wire system is in a pedal-on state, the brake-by-wire system exits the pedal-on state only after detecting that the brake pedal is fully released.

[0063] If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

[0064] Optionally, the controller is also used to control the manual cylinder circuit isolation valve to remain open and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain closed after entering the mechanical backup braking mode, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side braking circuit. When the brake pedal is stepped on to build pressure, the connected braking circuit pressure is established normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0065] Optionally, the controller is also used to control the manual cylinder circuit isolation valve to change from an open state to a closed state, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to change from a closed state to an open state after entering the normal wire control braking mode, and measure the pressure in the manual cylinder and the simulation cylinder through the manual cylinder pressure sensor, and measure the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side through the servo cylinder pressure sensor.

[0066] According to a third aspect of the present application, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method described in the first aspect is implemented.

[0067] According to a fourth aspect of the present application, a computer program product is provided. When the computer program product is run on a computer, the computer is caused to execute the method described in the first aspect.

[0068] The technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0069] When the brake-by-wire system is powered on normally, there are no faults, and it is in the pedal-powered state, the pressure in the manual cylinder is determined to determine whether to enter the pedal-powered braking mode or the normal brake-by-wire mode. If the pressure in the manual cylinder is greater than the first pressure threshold, the pedal-powered braking mode is entered. In the pedal-powered braking mode, the analog cylinder circuit isolation valve remains in the closed state, and the manual cylinder circuit isolation valve changes from the open state to the closed state after power is applied. In this way, the brake fluid in the manual cylinder will be isolated from the circuits after the analog cylinder circuit isolation valve and the manual cylinder circuit isolation valve, thereby preventing the pedal from suddenly sinking when the brake pedal is deeply pressed to power on. In addition, in the case that the brake pedal cannot be further pressed, the target pressure is determined based on the pressure in the manual cylinder to adjust the brake pressure to ensure the output of the brake pressure, thereby avoiding the problem of the car slipping after the parking is released while the brake pedal is pressed on a slope. If the pressure in the manual cylinder is less than or equal to the first pressure threshold, the vehicle directly enters normal brake-by-wire mode. At this point, there will be no noticeable pedal sinking that the driver will notice. Furthermore, because the vehicle is in normal brake-by-wire mode, subsequent braking with the brake pedal will not experience any abnormal brake pedal feel. This demonstrates that the present embodiment prioritizes brake pressure output, ensuring both safety and a good brake pedal feel, thus ensuring a superior driver experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0071] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0072] Figure 1 A schematic diagram of a fully decoupled brake-by-wire system in an embodiment of the present application;

[0073] Figure 2 A flow chart of a fully decoupled brake-by-wire method in an embodiment of the present application;

[0074] Figure 3 A schematic diagram of a fully decoupled brake-by-wire system in mechanical backup braking mode;

[0075] Figure 4 A schematic diagram of a fully decoupled brake-by-wire system in normal brake-by-wire mode;

[0076] Figure 5 This is an illustration of the data results after switching from mechanical backup braking mode to normal wire control braking mode;

[0077] Figure 6 This is another flow chart of the fully decoupled brake-by-wire method in the embodiment of the present application;

[0078] Figure 7 This is another flow chart of the fully decoupled brake-by-wire method in the embodiment of the present application;

[0079] Figure 8 This is another flow chart of the fully decoupled brake-by-wire method in the embodiment of the present application;

[0080] Figure 9 Schematic diagram of the structure of a fully decoupled wire-controlled brake system in an embodiment of the present application. DETAILED DESCRIPTION

[0081] In order to more clearly understand the above-mentioned objectives, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0082] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application can also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present application, not all of the embodiments.

[0083] The brake-by-wire system of the embodiment of the present application is a fully decoupled brake-by-wire system (DBS, Decoupled Brake System). Because of the isolation of the solenoid valve, it can achieve a fully decoupled state, that is, the pedal feel will not be affected by the execution circuit at all, and the pedal depression depth and the final output hydraulic pressure can be completely decoupled in the corresponding relationship. Therefore, it is convenient to perform many complex and intelligent control logics.

[0084] See also Figure 1 , Figure 1This is a schematic diagram of the principle of a fully decoupled, wire-controlled brake system in an embodiment of the present application. The wire-controlled brake system includes: a brake pedal 1, a mechanical push rod 2, a travel sensor 3, a fluid reservoir 4, a first piston and spring 5 in the manual cylinder, a second piston and spring 6 in the manual cylinder, a manual cylinder pressure sensor 7, a manual cylinder circuit isolation valve 8, a manual cylinder circuit isolation valve 9, a simulation cylinder circuit isolation valve 10, a simulation cylinder 11, a servo cylinder circuit isolation valve 12, a servo cylinder circuit isolation valve 13, a servo cylinder pressure sensor 14, a servo cylinder body 15, a servo cylinder piston 16, a ball screw drive mechanism 17, and a servo motor 18. The remaining components are the brake fluid circuit and the associated filter and one-way valve. The circuit is filled with brake fluid, and the fluid level in the fluid reservoir 4 is between the minimum and maximum positions. The manual cylinder circuit isolation valves 8 and 9 are both normally open valves, while the simulation cylinder circuit isolation valves 10, the servo cylinder circuit isolation valves 12, and the servo cylinder circuit isolation valves 13 are all normally closed valves.

[0085] Figure 1 In the car, the Electronic Stability Control (ESC) connects to the two circuits of the DBS and to the four wheel brakes. The symbols FL, FR, RL, and RR in the figure represent the four wheel brakes, respectively.

[0086] See also Figure 2 , Figure 2 This is a flow chart of a fully decoupled brake-by-wire method according to an embodiment of the present application, which is applied to a brake-by-wire system and may include the following steps:

[0087] Step S202 , detecting whether the brake-by-wire system is powered on normally.

[0088] If the brake-by-wire system is not powered on normally, step S204 is executed; if the brake-by-wire system is powered on normally, step S206 is executed.

[0089] Step S204: Entering the mechanical backup braking mode.

[0090] In mechanical backup braking mode, no control strategy is involved. If the brake-by-wire system is not powered on properly, manual cylinder circuit isolation valves 8 and 9 are controlled to remain open, while analog cylinder circuit isolation valves 10, servo cylinder circuit isolation valves 12, and servo cylinder circuit isolation valves 13 are controlled to remain closed.

[0091] Combine Figure 3In the mechanical backup braking mode, the brake pedal 1 is depressed, pushing the mechanical push rod 2 to the left. At this time, the piston in the manual cylinder moves to the left, and the piston spring is compressed. After the piston in the manual cylinder moves to the left, it passes the brake fluid circuit inlet of the two piston chambers in the manual cylinder. The brake fluid in the two piston chambers of the manual cylinder is sealed and compressed, and the further the piston is pushed to the left, the higher the pressure in the sealed circuit. At this time, since the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are in the open state, the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel side brake circuit. When the brake pedal is depressed to build pressure, the pressure of the connected brake circuit is built up normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0092] Step S206 , detecting whether there is a fault in the brake-by-wire system.

[0093] In this embodiment of the present application, a fault in the brake-by-wire system can be determined by detecting whether the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve are faulty. If none of the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve are faulty, the brake-by-wire system is determined to be faulty. If at least one of the servo motor, the manual cylinder circuit isolation valve, and the servo cylinder circuit isolation valve is faulty, the brake-by-wire system is determined to be faulty.

[0094] If there is a fault in the wire control braking system, step S204 is executed. At this time, the motor and all solenoid valves (manual cylinder circuit isolation valve 8, manual cylinder circuit isolation valve 9, simulation cylinder circuit isolation valve 10, servo cylinder circuit isolation valve 12 and servo cylinder circuit isolation valve 13) are not controlled; if there is no fault in the wire control braking system, step S208 is executed.

[0095] Step S208 , detecting whether the brake-by-wire system is in a pedal-powered state.

[0096] After powering on by pressing the brake pedal, as long as the driver has not completely released the brake pedal, the brake-by-wire system is considered to be in the pedal-on state. That is, if the brake pedal is detected as being pressed at the moment of powering on, i.e., the controller recognizes that the brake pedal is pressed at the moment of powering on, the brake-by-wire system is determined to be in the pedal-on state. Conversely, if the brake pedal is detected as not being pressed at the moment of powering on, i.e., the controller recognizes that the brake pedal is not pressed at the moment of powering on, the brake-by-wire system is determined to be not in the pedal-on state.

[0097] Once the brake-by-wire system is recognized as being in the pedal-on state, if the exit conditions are not met, the system remains in the pedal-on state. If the brake-by-wire system is in the pedal-on state, it will exit the pedal-on state only when the brake pedal is fully released.

[0098] If the brake-by-wire system is not in the pedal-on state, step S210 is executed, i.e., the system enters the normal brake-by-wire mode. All subsequent braking operations are in the normal brake-by-wire mode. If the brake-by-wire system is in the pedal-on state, step S212 is executed.

[0099] Step S210, entering normal brake-by-wire mode.

[0100] Combine Figure 4 After entering the normal wire control braking mode, all solenoid valves are energized and activated, that is, the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state, and the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are controlled to change from a closed state to an open state. The pressure in the manual cylinder and the simulation cylinder can be measured by the manual cylinder pressure sensor, and the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side can be measured by the servo cylinder pressure sensor.

[0101] When the brake pedal is depressed, human-generated hydraulic pressure builds up before the manual cylinder circuit isolation valves 8 and 9. At this point, the pressure measured by the manual cylinder pressure sensor 7 represents the pressure in the manual cylinder and the simulated cylinder. Furthermore, the pressure generated by the servo motor 18 driving the ball screw drive mechanism 17 forward to compress the brake fluid in the servo cylinder piston 16 builds up in the fluid circuit after the manual cylinder circuit isolation valves 8 and 9. At this point, the pressure measured by the servo cylinder pressure sensor 14 represents the pressure in the hydraulic circuits before and after the servo cylinder body 15, the servo cylinder circuit isolation valves 12 and 13, and the pressure in the ESC and wheel side.

[0102] Step S212: Determine whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold.

[0103] In the embodiment of the present application, the brake-by-wire system is tested on a bench when switching from the mechanical backup braking mode to the normal brake-by-wire mode. The data results obtained can be seen in Figure 5 The horizontal axis represents the pressure in the manual cylinder at the moment the pedal is pressed and the power is turned on, that is, the pressure value measured by the manual cylinder pressure sensor 7.

[0104] The pedal force change value in the curve refers to the difference calculated based on the values ​​collected at different times by the external pedal force sensor. That is, the value obtained by collecting the pedal force value at the moment the brake pedal 1 is powered on and the lowest value within 0.5 seconds thereafter is calculated. The difference between the two values ​​can be used to intuitively reflect the change in pedal force after the brake pedal is powered on.

[0105] The mechanical push rod stroke value in the curve refers to the value collected by the stroke sensor 3 at the moment the pedal is pressed and the power is turned on.

[0106] The manual cylinder pressure change value in the curve refers to the difference calculated based on the values ​​collected by the manual cylinder pressure sensor 7 at different times, that is, the pressure value at the moment the brake pedal 1 is powered on and the lowest pressure value within 0.5s thereafter. The value obtained by taking the difference between the two can reflect the manual cylinder pressure changes at the moment the brake pedal is powered on and thereafter.

[0107] The mechanical push rod stroke change value in the curve refers to the difference calculated from the values ​​collected by the stroke sensor 3 at different times, that is, the stroke value at the moment the brake pedal 1 is powered on and the lowest stroke value within 0.5 seconds thereafter. The value obtained by taking the difference between the two can intuitively reflect the severity of the pedal sinking when the brake pedal is powered on.

[0108] It can be seen that when the pedal is pressed shallowly when the power is turned on (for example, the manual cylinder pressure is less than P2), the pedal force and the stroke of the mechanical push rod (or pedal stroke) will change less, and the instantaneous pressure drop when simulating the cylinder balance pressure will be smaller, that is, the smaller the change value of the manual cylinder pressure, it will hardly cause the pedal to sink, or the caused sinking will be very small, not enough to cause the pedal to sink so that the driver feels uncomfortable.

[0109] The specific analysis process is as follows: when the pedal is pressed shallowly in the backup braking mode (for example, the manual cylinder pressure is less than P2), there is a certain small pressure in the braking system. When the power is turned on at this time, the simulation cylinder circuit isolation valve 10 is opened, and the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are closed. The simulation cylinder 11 needs to balance the pressure, but because the braking system pressure itself is small, the piston of the simulation cylinder 11 does not need to move too much, so the pressure changes transmitted to the manual cylinder, the changes in the stroke transmitted to the mechanical push rod and the changes in the pedal force will be very small, so as not to cause discomfort to the driver.

[0110] When the pedal is pressed deeper when the power is turned on (for example, the manual cylinder pressure is greater than P2), the pedal force and the stroke of the mechanical push rod (or pedal stroke) will change more, and the instantaneous pressure drop when simulating the cylinder balance pressure will be greater, that is, the greater the change in the manual cylinder pressure, which will cause greater pedal sinking and a worse experience.

[0111] The specific analysis process is as follows: when the pedal is pressed deeply in the backup braking mode (for example, the manual cylinder pressure is greater than P2), there is a large pressure in the braking system. When the power is turned on at this time, the simulation cylinder circuit isolation valve 10 is opened, and the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are closed. The simulation cylinder 11 needs to balance the pressure, but because the braking system pressure itself is relatively large, the piston of the simulation cylinder 11 needs to move a large stroke in a short time, so the pressure changes transmitted to the manual cylinder, the changes in the stroke transmitted to the mechanical push rod and the changes in the pedal force will be large, which will cause discomfort to the driver.

[0112] Based on the above analysis, the embodiment of the present application can determine whether to enter the pedal-operated electric braking mode or the normal brake-by-wire mode by determining the pressure in the manual cylinder. If the pressure in the manual cylinder is less than or equal to the first pressure threshold (i.e., P2), step S210 is executed, directly entering the normal brake-by-wire mode. At this time, there will be no obvious pedal sinking that the driver will notice. Because it is in the normal brake-by-wire mode, there will be no abnormal brake pedal feel when the pedal is further pressed. If the pressure in the robot manual cylinder is greater than the first pressure threshold, step S214 is executed.

[0113] Step S214, entering the pedal-powered braking mode.

[0114] In pedal-powered braking mode, the analog cylinder circuit isolation valve remains closed, while the manual cylinder circuit isolation valve switches from open to closed upon power-up. A first target brake pressure is determined based on the stroke of the mechanical pushrod. A second target brake pressure is determined based on the pressure detected by the manual cylinder pressure sensor. The larger of the first and second target brake pressures is selected as the target brake pressure and output. Specifically, when a target brake pressure is set, the controller activates the motor, which, through the transmission mechanism, drives the servo cylinder piston to compress the brake fluid, establishing the corresponding brake pressure.

[0115] In this mode, the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9 are closed at the moment the brake pedal is powered on, and the simulation cylinder circuit isolation valve 10 is kept closed. In this way, the brake fluid in the manual cylinder will be isolated from the circuits after the simulation cylinder circuit isolation valve 10 and after the manual cylinder circuit isolation valve 8 and the manual cylinder circuit isolation valve 9, thereby preventing the pedal from suddenly sinking when the brake pedal is powered on when it is deeply depressed.

[0116] Although the brake pedal cannot be depressed any further after the manual cylinder circuit isolation valve 8, the manual cylinder circuit isolation valve 9 and the simulation cylinder circuit isolation valve 10 are closed, if the force of pressing the brake pedal 1 is further increased, the measurement value of the manual cylinder pressure sensor 7 will increase further. The increase in this value will be used as a control basis to increase the target pressure of the braking system, thereby generating a greater braking pressure at the wheel side to meet the braking requirements.

[0117] For example, when the driver applies power by pressing the brake pedal deeply (i.e., the pressure in the manual cylinder is much greater than P2), the system enters the pedal-on-power-brake mode. At this point, the target brake pressure is already high enough to prevent the vehicle from rolling down a slope after pressing the pedal and releasing the parking brake. When the driver applies power by pressing the brake pedal lightly (i.e., the pressure in the manual cylinder is slightly greater than P2), the system enters the pedal-on-power-brake mode. Further increasing the force applied to the brake pedal increases the target pressure of the brake system based on the value measured by the manual cylinder pressure sensor 7, ensuring that the vehicle does not roll down a slope after pressing the pedal and releasing the parking brake on a slope.

[0118] Step S216 , detecting whether the brake-by-wire system is powered off.

[0119] If it is detected that the brake-by-wire system is not powered off, the process returns to step S206 , ie, the above process is executed in a loop; if it is detected that the brake-by-wire system is powered off, the process ends.

[0120] The wire control braking method of the embodiment of the present application determines whether to enter the pedal-powered braking mode or the normal wire control braking mode by judging the pressure in the manual cylinder when the wire control braking system is normally powered on, there is no fault and it is in the pedal-powered state. If the pressure in the manual cylinder is greater than the first pressure threshold, the pedal-powered braking mode is entered. In the pedal-powered braking mode, the simulation cylinder circuit isolation valve remains in a closed state, and the manual cylinder circuit isolation valve changes from an open state to a closed state after power is applied. In this way, the brake fluid in the manual cylinder will be isolated from the circuits after the simulation cylinder circuit isolation valve and the manual cylinder circuit isolation valve, thereby avoiding the sudden sinking of the pedal when the brake pedal is deeply pressed to power on. In addition, in the case that the brake pedal cannot be further pressed, the target brake pressure is determined based on the pressure in the manual cylinder to adjust the target brake pressure to ensure the output of the brake pressure, thereby avoiding the problem of the car slipping after the brake pedal is pressed to power on and the parking is released at the same time under slope conditions. If the pressure in the manual cylinder is less than or equal to the first pressure threshold, the vehicle directly enters normal brake-by-wire mode. At this point, there will be no noticeable pedal sinking that the driver will notice. Furthermore, because the vehicle is in normal brake-by-wire mode, subsequent braking with the brake pedal will not experience any abnormal brake pedal feel. This demonstrates that the present embodiment prioritizes brake pressure output, ensuring both safety and a good brake pedal feel, thus ensuring a superior driver experience.

[0121] In the pedal-operated braking mode, when the brake pedal is slightly released but not completely released, the vehicle may slip on a slope due to the reduction in the target pressure of the braking system. At this time, it is necessary to continue to press the pedal to increase the target braking force. However, because it is in the pedal-operated braking mode, the brake pedal cannot be continued to be pressed after it has been released to the point where it is not completely released, which may cause a poor experience.

[0122] To avoid this problem, in the pedal-operated electric braking mode, if the conditions for entering the normal wire-controlled braking mode are not met (i.e., the pressure in the manual cylinder in the pedal-operated electric braking mode is not less than P1), the highest target braking pressure in this mode will always be maintained (this highest target braking pressure will be subject to a maximum value limit, i.e., it will not exceed the original maximum braking pressure limit value) until the pressure in the manual cylinder is less than P1 and then the target braking pressure is released to 0. Subsequent braking will enter the normal wire-controlled braking mode, and the highest target pressure maintenance logic of the pedal-operated electric braking mode will no longer be executed.

[0123] See also Figure 6 ,exist Figure 2 Based on the embodiment, the following steps may also be included:

[0124] Step S2151 : When the brake-by-wire system is in the pedal-operated braking mode, the pressure in the manual cylinder is detected.

[0125] Step S2152: Determine whether the pressure in the manual cylinder is less than a second pressure threshold, wherein the second pressure threshold is less than the first pressure threshold.

[0126] If the pressure in the manual cylinder is less than the second pressure threshold (ie, P1), step S210 is executed, i.e., the electric braking mode is switched from the pedal-operated braking mode to the normal wire-controlled braking mode. If the pressure in the manual cylinder is greater than or equal to the second pressure threshold, step S216 is executed.

[0127] Considering that the driver may release the brake pedal slightly (not completely) and then continue to press it quickly in the pedal-powered braking mode, if the corresponding valve control (manual cylinder circuit isolation valve 8 and manual cylinder circuit isolation valve 9 are energized to close, and analog cylinder circuit isolation valve 10 is energized to open) is not fast enough when switching from the pedal-powered braking mode to the normal wire-controlled braking mode, it will still cause a slight hitch when the brake pedal is quickly pressed. By designing the threshold for entering the pedal-powered braking mode as the first pressure threshold and the threshold for exiting the pedal-powered braking mode as the second pressure threshold, abnormal pedal feel can be avoided and the normal wire-controlled braking mode can be entered more quickly.

[0128] Optionally, if slipping is detected in the pedal-operated electric braking mode, the target brake pressure can be increased according to the set increase gradient control based on the slipping state. The increased target brake pressure is not limited by the maximum brake pressure of the vehicle in a stationary state before slipping, but is limited by the maximum allowable working pressure of the DBS system, that is, the increased target brake pressure is not greater than the maximum allowable working pressure of the brake-by-wire system. After the slipping is detected to stop, if the increased target brake pressure is less than or equal to the maximum brake pressure limit value of the vehicle in a stationary state before slipping, the increased target brake pressure is maintained. If the increased target brake pressure is greater than the maximum brake pressure limit value of the vehicle in a stationary state before slipping, the increased target brake pressure is reduced to the maximum brake pressure limit value according to the set decrease gradient, and when the pressure in the manual cylinder is less than the second pressure threshold, the pedal-operated electric braking mode is exited and the normal brake-by-wire mode is entered, which can help the driver prevent the vehicle from slipping when starting on a slope.

[0129] See also Figure 7 , Figure 7 This is another flow chart of the fully decoupled wire control brake method in the embodiment of the present application. Figure 2 Based on the embodiment, the following steps may also be included:

[0130] Step S207 : If the vehicle is equipped with an electronic parking brake system, it is detected whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched after power-on.

[0131] If the electronic parking brake system is in the unapplied state, or the electronic parking brake system is in the applied state and its state has been switched before, execute step S208; if the electronic parking brake system is in the applied state and its state has not been switched before, execute step S204, i.e. enter the mechanical backup brake mode.

[0132] For vehicles equipped with an electronic parking brake system, if the EPB system is in the applied state and has not previously switched states while the brake pedal is pressed, the mechanical backup braking mode logic can be maintained. If the EPB system is not applied, or if it is applied but has previously switched states (e.g., the EPB system has switched from applied to released to applied while the brake pedal is pressed), the system switches to pedal-pressed braking mode. This prevents sudden pedal sinking and possible vehicle rollaway due to insufficient brake pressure.

[0133] See also Figure 8 , Figure 8 This is another flow chart of the fully decoupled wire control brake method in the embodiment of the present application. Figure 2 Based on the embodiment, the following steps may also be included:

[0134] Step S2091 : performing signal verification on the pressure sensor of the electronic stability control system itself to determine whether the first pressure measurement value is valid.

[0135] If the first pressure measurement value is valid, step S2092 is executed; if the first pressure measurement value is invalid, step S2093 is executed.

[0136] Step S2092: Perform signal verification on the manual cylinder pressure sensor to determine whether the second pressure measurement value is valid.

[0137] If the second pressure measurement value is invalid, step S204 is executed. If the second pressure measurement value is valid, step S2094 is executed.

[0138] Step S2093: Set the first pressure measurement value to 0.

[0139] It should be noted that Figure 8 The order of signal verification for the electronic stability control system's own pressure sensor and the fully decoupled brake-by-wire system's manual cylinder pressure sensor is not limited. The former can be verified first, followed by the latter, or the latter can be verified first, followed by the former. If the first pressure measurement value is invalid, step S2093 is executed; if the second pressure measurement value is invalid, step S204 is executed; if both the first and second pressure measurements are valid, step S2094 is executed.

[0140] Step S2094: Compare the first pressure measurement value and the second pressure measurement value to determine whether there is an abnormality in the pressure in the brake-by-wire system.

[0141] In an embodiment of the present application, the electronic stability control system itself may also include a pressure sensor for measuring the hydraulic value of the DBS entering the electronic stability control system. In the mechanical backup braking mode, the piston chamber of the manual cylinder of the DBS will be directly connected to the ESC, and in the brake holding stage, the pressure in the hydraulic circuit will be equal everywhere. Among them, brake holding means that the pedal remains stationary after being stepped on; for a closed hydraulic system, the static pressure is equal everywhere; if there is a pressure difference, it will cause movement and it is no longer static pressure. For a normal system, due to the difference in the accuracy of the pressure sensors of DBS and ESC, the values ​​measured by the two will not be exactly the same, but the difference is small. Optionally, if the absolute value of the difference between the first pressure measurement value and the second pressure measurement value is less than or equal to the pressure difference threshold, it is determined that there is no abnormality in the pressure in the wire control brake system.

[0142] Before the system is powered on, the brake pedal is depressed a certain depth. However, because the system is not powered on yet, it cannot obtain the readings from each sensor. At the moment of power-on, the DBS and ESC controllers acquire signals from their respective pressure sensors. If the difference between the first and second pressure measurements exceeds the pressure difference threshold, this indicates a possible pressure leak in the second chamber of the manual brake cylinder, resulting in an abnormal signal. This is considered a DBS pressure signal failure, confirming a pressure anomaly within the brake-by-wire system.

[0143] If the difference between the second pressure measurement value and the first pressure measurement value is greater than the pressure difference threshold, it means that there may be a problem with the ESC pressure sensor, but it does not affect the DBS logic of powering on by pressing the pedal. Therefore, it can be determined that there is no abnormality in the pressure of the wire control brake system.

[0144] If the pressure in the brake-by-wire system is normal, the step of determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold is performed. If the pressure in the brake-by-wire system is abnormal, the mechanical backup braking mode is entered.

[0145] It should be noted that after determining that there is an abnormality in the pressure in the wire control brake system, if the pedal power-on state is exited at this time, the normal wire control brake mode can still be entered.

[0146] The wire control braking method of the embodiment of the present application takes into account special abnormal situations that may exist in the system and improves the logic of using the pressure in the human cylinder for wire control braking.

[0147] It should be noted that although the steps of the method of the present application are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all steps must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0148] The present application also provides a fully decoupled wire-controlled brake system. Figure 9 The brake-by-wire system 900 includes a controller 902, a brake pedal 904, a mechanical push rod 906, a travel sensor 908, a fluid reservoir 910, a manual cylinder 912 including a piston and a spring, a manual cylinder pressure sensor 914, a manual cylinder circuit isolation valve 916, a simulation cylinder circuit isolation valve 918, a simulation cylinder 920, a servo cylinder circuit isolation valve 922, a servo cylinder pressure sensor 924, a servo cylinder body 926, a servo cylinder piston 928, a ball screw transmission mechanism 930, and a servo motor 932.

[0149] Controller 902 is configured to detect whether the brake-by-wire system is powered on normally; if the brake-by-wire system is not powered on normally, enter a mechanical backup braking mode; if the brake-by-wire system is powered on normally, detect whether the brake-by-wire system is faulty; if the brake-by-wire system is faulty, enter a mechanical backup braking mode; if the brake-by-wire system is not faulty, detect whether the brake-by-wire system is in a pedal-powered state; and,

[0150] If the brake-by-wire system is not in the pedal-powered state, it enters the normal brake-by-wire mode; if the brake-by-wire system is in the pedal-powered state, it determines whether the pressure in the manual cylinder is greater than the first pressure threshold at the moment of power-on; if the pressure in the manual cylinder is less than or equal to the first pressure threshold, it enters the normal brake-by-wire mode; if the pressure in the manual cylinder is greater than the first pressure threshold, it enters the pedal-powered braking mode; in the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in the closed state, and the manual cylinder circuit isolation valve is controlled to change from the open state to the closed state after power is supplied, and the first target braking pressure is determined according to the stroke of the mechanical push rod; the second target braking pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target braking pressure and the second target braking pressure is selected as the target braking pressure, and the braking pressure is output;

[0151] Check whether the brake-by-wire system is powered off;

[0152] If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault;

[0153] If it is detected that the brake-by-wire system is powered off, the process ends.

[0154] Optionally, the controller 902 is also used for comparing and verifying the pressure signal measurement values ​​and judging the entry into related modes, that is, when the wire control brake system is in the pedal-powered state, before judging whether the pressure in the manual cylinder at the moment of power-on is greater than the first pressure threshold, the signal of the pressure sensor of the electronic stability control system itself is first verified to judge whether the first pressure measurement value is valid; the signal of the manual cylinder pressure sensor is verified to judge whether the second pressure measurement value is valid; if the first pressure measurement value is invalid, the first pressure measurement value is set to 0; if the second pressure measurement value is invalid, the mechanical backup braking mode is entered; if both the first pressure measurement value and the second pressure measurement value are valid, the first pressure measurement value measured by the pressure sensor of the electronic stability control system itself and the second pressure measurement value measured by the manual cylinder pressure sensor are compared to determine whether there is an abnormality in the pressure in the wire control brake system; if there is no abnormality in the pressure in the wire control brake system, the step of judging whether the pressure in the manual cylinder at the moment of power-on is greater than the first pressure threshold is executed; if there is an abnormality in the pressure in the wire control brake system, the mechanical backup braking mode is entered.

[0155] Optionally, the controller 902 is also used to detect the pressure in the manual cylinder when the wire control braking system is in the pedal-operated electric braking mode. If the pressure in the manual cylinder is less than a second pressure threshold, the normal wire control braking mode is entered, wherein the first pressure threshold is greater than the second pressure threshold.

[0156] Optionally, the controller is further used to, before detecting whether the brake-by-wire system is in the pedal-powered state, if the vehicle is equipped with an electronic parking brake system, detect whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched after power-on; if the electronic parking brake system is in the unengaged state, or the electronic parking brake system is in the engaged state and its state has ever been switched, execute the step of detecting whether the brake-by-wire system is in the pedal-powered state; if the electronic parking brake system is in the engaged state and its state has ever been switched, enter the mechanical backup braking mode.

[0157] Optionally, the controller 902 is also used to increase the target brake pressure according to a set increasing gradient based on the slipping state if slipping is detected in the pedal-operated electric braking mode, wherein the increased target brake pressure is not greater than the maximum allowable working pressure of the wire control brake system; after detecting that the slipping has stopped, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is in a stationary state before slipping, the increased target brake pressure is reduced to the maximum brake pressure limit value according to a set decreasing gradient, and when the pressure in the manual cylinder is less than the second pressure threshold, the normal wire control brake mode is entered.

[0158] Optionally, the controller 902 is specifically configured to determine whether there is an abnormality in the pressure of the brake-by-wire system by performing the following steps:

[0159] If the absolute value of the difference between the first pressure measurement value and the second pressure measurement value is less than or equal to the pressure difference threshold, determining that there is no abnormality in the pressure within the brake-by-wire system;

[0160] If a difference between the first pressure measurement value and the second pressure measurement value is greater than a pressure difference threshold, determining that there is an abnormality in the pressure within the brake-by-wire system;

[0161] If the difference between the second pressure measurement and the first pressure measurement is greater than the pressure difference threshold, it is determined that there is no abnormality in the pressure within the brake-by-wire system.

[0162] Optionally, the controller 902 is specifically configured to detect whether the brake-by-wire system is in a pedal-powered state by performing the following steps:

[0163] If the brake pedal is detected to be depressed at the moment of power-on, it is determined that the brake-by-wire system is in the pedal-on state;

[0164] When the brake-by-wire system is in the pedal-on state, it will exit the pedal-on state only when it detects that the brake pedal is fully released;

[0165] If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

[0166] Optionally, the controller 902 is also used to control the manual cylinder circuit isolation valve to remain open and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain closed after entering the mechanical backup braking mode, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side braking circuit. When the brake pedal is stepped on to build pressure, the connected braking circuit pressure is established normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

[0167] Optionally, the controller 902 is also used to control the manual cylinder circuit isolation valve to change from an open state to a closed state, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to change from a closed state to an open state after entering the normal wire control braking mode, and measure the pressure in the manual cylinder and the simulation cylinder through the manual cylinder pressure sensor, and measure the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side through the servo cylinder pressure sensor.

[0168] The specific details of each module or unit in the above system have been described in detail in the corresponding method, so they will not be repeated here.

[0169] It should be noted that, although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiment of the application, the features and functions of two or more modules or units described above can be concretized in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into multiple modules or units to be concretized.

[0170] In an embodiment of the present application, a computer-readable storage medium is further provided, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned wire control braking method is implemented.

[0171] It should be noted that the computer-readable storage medium shown in this application can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or component, or any combination thereof. More specific examples of computer-readable storage media can include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, device or device. The program code contained on the computer-readable storage medium can be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, radio frequency, etc., or any suitable combination thereof.

[0172] In an embodiment of the present application, a computer program product is further provided. When the computer program product is run on a computer, the computer is caused to execute the above-mentioned wire control braking method.

[0173] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0174] The foregoing description is intended only to provide specific embodiments of the present application, which will enable those skilled in the art to understand and implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments described herein, but is intended to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A fully decoupled wire control brake method, characterized in that: Applied to a brake-by-wire system, the brake-by-wire system, the method comprising: Check whether the brake-by-wire system is powered on normally; If the wire control brake system is not powered on normally, the system enters the mechanical backup brake mode; If the brake-by-wire system is powered on normally, detecting whether the brake-by-wire system has a fault; If there is a fault in the brake-by-wire system, a mechanical backup braking mode is entered; If there is no fault in the brake-by-wire system, detecting whether the brake-by-wire system is in a pedal-on state; If the brake-by-wire system is not in the pedal-powered state, the normal brake-by-wire mode is entered; If the brake-by-wire system is in a pedal-powered state, determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold; If the pressure in the manual cylinder is less than or equal to a first pressure threshold, the normal brake-by-wire mode is entered; If the pressure in the manual cylinder is greater than a first pressure threshold, entering a pedal-operated electric braking mode; In the pedal-powered braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after power is applied. A first target brake pressure is determined according to the stroke of the mechanical push rod; a second target brake pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target brake pressure and the second target brake pressure is selected as the target brake pressure, and the brake pressure is output; detecting whether the brake-by-wire system is powered off; If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault; If it is detected that the brake-by-wire system is powered off, the process ends.

2. The method according to claim 1, characterized in that Before determining whether the pressure in the manual cylinder is greater than a first pressure threshold at the moment of power-on, the method further includes: If the brake-by-wire system is in a pedal-powered state, a signal check is performed on the pressure sensor of the electronic stability control system itself to determine whether the first pressure measurement value is valid; a signal check is performed on the pressure sensor of the manual cylinder to determine whether the second pressure measurement value is valid; If the first pressure measurement value is invalid, setting the first pressure measurement value to 0; If the second pressure measurement is invalid, the mechanical backup braking mode is entered; If both the first pressure measurement value and the second pressure measurement value are valid, determining whether there is an abnormality in the pressure within the brake-by-wire system by comparing the first pressure measurement value and the second pressure measurement value; If there is no abnormality in the pressure in the brake-by-wire system, executing the step of determining whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold; If there is an abnormality in the pressure of the wire control brake system, the mechanical backup braking mode is entered.

3. The method according to claim 1, characterized in that The method further comprises: When the wire control brake system is in the pedal-operated electric braking mode, the pressure in the manual cylinder is detected. If the pressure in the manual cylinder is less than a second pressure threshold, the normal wire control brake mode is entered, wherein the first pressure threshold is greater than the second pressure threshold.

4. The method according to claim 1, wherein Before detecting whether the brake-by-wire system is in a pedal-powered state, the method further includes: If the vehicle is equipped with an electronic parking brake system, check whether the electronic parking brake system is in the engaged state and whether the state of the electronic parking brake system has never been switched since power was applied; If the electronic parking brake system is in the unapplied state, or the electronic parking brake system is in the applied state and its state has been switched, then executing the step of detecting whether the brake-by-wire system is in the pedal-on state; If the electronic parking brake system is in the applied state and its state has not been switched before, it enters the mechanical backup brake mode.

5. The method according to claim 1, wherein The method further comprises: If vehicle slippage is detected in the pedal-operated power-on braking mode, the target brake pressure is increased according to a set increase gradient based on the vehicle slippage state, wherein the increased target brake pressure is not greater than the maximum allowable operating pressure of the brake-by-wire system; After detecting that the vehicle has stopped slipping, if the increased target brake pressure is greater than the maximum brake pressure limit value when the vehicle is stationary before slipping, the increased target brake pressure will be reduced to the maximum brake pressure limit value according to the set descent gradient, and the normal wire control braking mode will be entered when the pressure in the manual cylinder is less than the second pressure threshold.

6. The method according to claim 2, characterized in that Comparing the first pressure measurement value and the second pressure measurement value to determine whether there is an abnormality in the pressure within the brake-by-wire system includes: If the absolute value of the difference between the first pressure measurement value and the second pressure measurement value is less than or equal to a pressure difference threshold, determining that there is no abnormality in the pressure in the brake-by-wire system; If a difference between the first pressure measurement value and the second pressure measurement value is greater than a pressure difference threshold, determining that a pressure abnormality exists in the brake-by-wire system; If the difference between the second pressure measurement and the first pressure measurement is greater than a pressure difference threshold, it is determined that there is no abnormality in the pressure within the brake-by-wire system.

7. The method according to any one of claims 1 to 5, characterized in that The detecting whether the brake-by-wire system is in a pedal-powered state includes: If it is detected at the moment of power-on that the brake pedal is depressed, it is determined that the brake-by-wire system is in a pedal-depressed power-on state; When the brake-by-wire system is in a pedal-on state, the brake-by-wire system exits the pedal-on state only after detecting that the brake pedal is fully released. If it is detected at the moment of power-on that the brake pedal is not depressed, it is determined that the brake-by-wire system is not in the pedal-depressed power-on state.

8. The method according to any one of claims 1 to 5, characterized in that After entering the mechanical backup braking mode, the method further includes: Control the manual cylinder circuit isolation valve to remain in the open state, and control the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve to remain in the closed state, so that the two piston chambers of the manual cylinder are connected to the electronic stability control system and the wheel-side brake circuit. When the brake pedal is stepped on to build up pressure, the connected brake circuit pressure is built up normally, and the pressure is greater than 0. The circuit pressure from the simulation cylinder circuit isolation valve to the simulation cylinder is 0, and the pressure before the servo cylinder circuit isolation valve and in the servo cylinder is also 0.

9. The method according to any one of claims 1 to 5, characterized in that After entering the normal brake-by-wire mode, the method further includes: The manual cylinder circuit isolation valve is controlled to change from an open state to a closed state, and the simulation cylinder circuit isolation valve and the servo cylinder circuit isolation valve are controlled to change from a closed state to an open state. The pressure in the manual cylinder and the simulation cylinder is measured by the manual cylinder pressure sensor, and the pressure in the servo cylinder body, the hydraulic circuits before and after the servo cylinder circuit isolation valve, the electronic stability control system and the wheel side are measured by the servo cylinder pressure sensor.

10. A fully decoupled brake-by-wire system, characterized in that: include: Controller, brake pedal, mechanical push rod, travel sensor, fluid reservoir, manual cylinder including piston and spring, manual cylinder pressure sensor, manual cylinder circuit isolation valve, simulation cylinder circuit isolation valve, simulation cylinder, servo cylinder circuit isolation valve, servo cylinder pressure sensor, servo cylinder body, servo cylinder piston, ball screw transmission mechanism and servo motor; The controller is configured to detect whether the brake-by-wire system is powered on normally; if the brake-by-wire system is not powered on normally, enter a mechanical backup braking mode; if the brake-by-wire system is powered on normally, detect whether the brake-by-wire system is faulty; If the brake-by-wire system has a fault, the system enters a mechanical backup braking mode; if the brake-by-wire system does not have a fault, the system detects whether the brake-by-wire system is in a pedal-powered state; as well as, If the brake-by-wire system is not in the pedal-powered state, the normal brake-by-wire mode is entered; if the brake-by-wire system is in the pedal-powered state, whether the pressure in the manual cylinder at the moment of power-on is greater than a first pressure threshold is determined; If the pressure in the manual cylinder is less than or equal to the first pressure threshold, the normal wire control braking mode is entered; if the pressure in the manual cylinder is greater than the first pressure threshold, the pedal-operated power-on braking mode is entered; in the pedal-operated power-on braking mode, the analog cylinder circuit isolation valve is controlled to remain in a closed state, and the manual cylinder circuit isolation valve is controlled to change from an open state to a closed state after power is applied, and a first target braking pressure is determined according to the stroke of the mechanical push rod; a second target braking pressure is determined according to the pressure detected by the manual cylinder pressure sensor, and the larger value of the first target braking pressure and the second target braking pressure is selected as the target braking pressure, and the braking pressure is output; detecting whether the brake-by-wire system is powered off; If it is detected that the brake-by-wire system is not powered off, returning to the step of detecting whether the brake-by-wire system has a fault; If it is detected that the brake-by-wire system is powered off, the process ends.

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