Direct-drive mechanical decoupling drive-by-wire brake and brake control method

Abstract

The invention provides a direct-drive mechanical decoupling drive-by-wire brake and a brake control method.The drive-by-wire brake comprises a brake master cylinder assembly, a brake pedal assembly, an electric drive assembly and an electronic control unit, and under the initial state, the energy recovery brake mode and the normal brake mode, a pedal push rod and a first brake piston are mechanically decoupled; all-electric driving is adopted for braking, and therefore the situation that in a non-decoupling braking system, after a driver steps on a brake pedal, a brake must participate in vehicle deceleration work, and kinetic energy is wasted is avoided; the electric driving assembly comprises an electric driving mechanism and a transmission mechanism, the electric driving mechanism and the transmission mechanism are coaxially arranged on the periphery of the pedal push rod in a sleeving mode, and a rotating part synchronously rotating with a rotor of the electric driving mechanism coaxially and directly converts rotating motion into linear motion to push a first brake piston; no gear combination needs to be additionally arranged in the middle for transmission switching of the radial position, so that the size of the brake is reduced, transmission loss is reduced, and the kinetic energy recovery rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking systems, and in particular to a direct-drive mechanical decoupling wire-controlled brake and a braking control method. Background Art

[0002] For vehicles equipped with a regenerative braking system, decelerating by depressing the brake pedal can convert the drive motor into a generator. The vehicle's inertia then rotates the generator, which then stores the electricity in the battery to recover kinetic energy. Simultaneously, the electromagnetic resistance of the generator slows the vehicle. Using vacuum assist requires an additional vacuum pump to assist braking, which not only increases system complexity but also potentially impacts the vehicle's lifespan and reliability.

[0003] Hydraulic brake-by-wire (EHB) systems are the mainstream technology in the current market. Based on traditional hydraulic braking systems, these systems utilize an electric motor, replacing a vacuum booster, to push the master cylinder piston, achieving braking. Furthermore, EHB eliminates the physical connection between the brake pedal and the braking force element, instead using electrical signals. This technology not only improves braking performance and safety but also opens up new possibilities for vehicle intelligence.

[0004] The most widely used hydraulic brake-by-wire system (EHB) currently uses the iBooster brake-by-wire booster series developed by Bosch as its core component. The working principle of iBooster is: when the driver steps on the brake pedal, the pedal connecting rod causes the brake push rod to displace, and the pedal stroke sensor detects the signal generated by the input push rod displacement and transmits its signal to the electronic control unit (ECU). The electronic control unit (ECU) calculates the torque that the motor should generate and sends the signal to the motor. After receiving the signal, the motor uses the gear transmission mechanism to convert the torque into servo braking force, and then works together with the push rod force generated by the driver stepping on the brake pedal. Finally, in the brake master cylinder, it is converted into brake fluid pressure to achieve braking. In simple terms, its work process can be summarized as: step on the pedal → provide displacement signal → motor rotation to provide power → finally achieve braking.

[0005] Bosch currently has two generations of iBooster brake-by-wire boosters, both of which have direct mechanical connections between the push rod and the rubber feedback disc, that is, non-decoupled mechanical connections, to ensure that the push rod can directly act on the rubber reaction disc during braking, thereby achieving efficient braking. In this non-decoupled brake-by-wire booster, during braking, the brake pedal force and brake fluid pressure are interrelated and cannot act independently. This means that when the brake pedal is depressed, the brake master cylinder generates hydraulic braking force, and the motor braking is only superimposed on this braking force. Therefore, there is a loss of some kinetic energy. If this part of the kinetic energy is also recovered, the kinetic energy recovery rate can be improved to a certain extent, and the cruising range can be increased.

[0006] In addition, both generations of iBooster brake-by-wire boosters are equipped with a motor and a reduction gear to provide power assistance. The reduction gear of the first-generation Bosch iBooster is a two-stage reduction gear. The torque of the power-assisting motor passes through the worm turbine for the first stage of deceleration and changes the direction of motion. The second-stage rack and pinion reduction mechanism converts the motor's rotational torque into axial thrust. The reduction gear of the second-generation Bosch iBooster is changed to a first-stage ball screw drive, with the aim of reducing the volume, improving control accuracy and significantly reducing costs. Since the output shaft and push rod of the motor in the iBooster are set as non-coaxial settings, the iBooster still has a high radial diameter, so that the brake still has a relatively large volume, and the reduction gear not only increases the torque but also changes the direction of motion, resulting in a certain degree of transmission loss. If the transmission loss of this part can be reduced, it can further help to improve the kinetic energy recovery rate and increase the cruising range.

[0007] In view of this, it is necessary to improve the wire control brake in the prior art to solve the above problems.

[0008] It should be noted that the above introduction to the background technology is merely for the purpose of providing a clear and complete description of the technical solutions of this application and facilitating understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0009] The object of the present invention is to provide a direct-drive mechanically decoupled brake-by-wire to solve the problems of insufficient kinetic energy recovery rate of the prior art brake-by-wire.

[0010] To achieve the above-mentioned object, the present invention provides a direct-drive mechanical decoupling brake-by-wire system, comprising a master cylinder assembly, a brake pedal assembly, an electric drive assembly, and an electronic control unit, wherein the master cylinder assembly, the brake pedal assembly, and the electric drive assembly are respectively connected to the electronic control unit for communication, wherein:

[0011] The master cylinder assembly includes a first brake piston, the brake pedal assembly includes a pedal push rod and a first sensor for monitoring the movement state of the pedal push rod, and an initial gap is provided between a pushing end of the pedal push rod and the first brake piston;

[0012] The electric drive assembly includes an electric drive mechanism and a transmission mechanism coaxially sleeved on the outer periphery of the pedal push rod, the electric drive mechanism having a rotor, the transmission mechanism including a rotating component and a linear pushing component transmission-connected to the rotating component, the transmission mechanism being disposed inside the electric drive mechanism and the rotating component rotating synchronously with the rotor, the rotating component coaxially sleeved on the outer periphery of the pedal push rod, and the pushing end of the linear pushing component abutting against the first brake piston;

[0013] In an initial state, an energy recovery braking mode, and a normal braking mode, the pedal push rod and the first brake piston are mechanically decoupled.

[0014] As a further improvement of the present invention, in an initial state, the initial gap between the pushing end of the pedal push rod and the first brake piston is configured to be in a range of 6 to 10 mm.

[0015] As a further improvement of the present invention, a critical stroke of the push rod is set for the brake push rod, and the critical stroke of the push rod is smaller than the initial gap. When the first sensor detects that the forward displacement of the pedal push rod exceeds the critical stroke of the push rod, the electronic control unit controls the operation of the electric drive assembly, and the linear propulsion component pushes the first brake piston forward.

[0016] As a further improvement of the present invention, the driving element of the electric drive assembly is a hollow motor, the rotor of the hollow motor is configured as a cylinder, and the rotating component is arranged on the inner circumference of the rotor and is connected to the rotor in synchronous rotation.

[0017] As a further improvement of the present invention, the rotating component is a screw, the linear pushing component is a nut with a built-in ball, and the linear pushing component is rollingly connected to the rotating component.

[0018] As a further improvement of the present invention, the electric drive assembly is configured with a second sensor for monitoring the motion state of the rotating component, the motion state data of the rotating component at least includes the rotation speed and the rotation angle, and the second sensor is communicatively connected to the electronic control unit.

[0019] As a further improvement of the present invention, the brake pedal assembly is also equipped with a pedal connecting rod and a pedal force simulator. The pedal connecting rod is rotatably connected to the pedal push rod. The pedal force simulator includes a first-stage spring, a second-stage spring and a limiter. The second-stage spring is sleeved on the outer periphery of the rear end of the pedal push rod, the front end of the second-stage spring is limited to the rear end of the electric drive assembly, the rear end of the first-stage spring is limited to the front side of the limiter, the limiter is sleeved on the outer periphery of the connection between the pedal push rod and the pedal connecting rod, and the first-stage spring is arranged inside the limiter.

[0020] To achieve the above object, the present invention also provides a brake control method, which is applied to a brake system including the above brake, and the control method includes:

[0021] Presetting a push rod critical stroke for the pedal push rod, wherein the push rod critical stroke is set to be smaller than an initial gap between the pedal push rod and the first brake piston;

[0022] Determining whether the forward displacement of the pedal push rod reaches the push rod critical stroke;

[0023] If so, the braking system determines whether to execute the energy recovery braking mode based on the comprehensive conditions of the vehicle;

[0024] When the energy recovery braking mode is executed, the electronic control unit controls the electric drive assembly to operate, and the linear propulsion component pushes the first brake piston forward.

[0025] As a further improvement of the present invention, the braking system has a braking system idle stroke. For the energy recovery braking mode, the first brake piston is preset with an initial propulsion stroke, and the initial propulsion stroke is preset to be smaller than the braking system idle stroke. When the stroke of the first brake piston propulsed by the linear propulsion component is within the range of the initial propulsion stroke, the decoupling gap between the pedal push rod and the first brake piston dynamically increases.

[0026] As a further improvement of the present invention, the electric drive component is configured to include a second sensor for monitoring the motion state of the rotating part, and the braking control method further includes: when judging whether the forward displacement of the pedal push rod reaches the critical stroke of the push rod, the motion state data of the rotating part monitored by the second sensor and the motion state data of the pedal push rod monitored by the first sensor are calculated. If the error exceeds a preset range, the input parameters of the electric drive component are adjusted to limit the error to within the preset range.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Compared to a non-decoupling braking system, where the brake must be used to decelerate the vehicle after the driver steps on the brake pedal, wasting kinetic energy, the wire control brake provided by the present application has a larger dynamic decoupling gap between the pedal push rod and the first brake piston in the energy recovery braking mode. This can improve the vehicle's kinetic energy recovery rate and increase the vehicle's range.

[0029] In normal braking mode, the pedal push rod remains mechanically separated from the first brake piston, allowing the brake-by-wire system to achieve decoupling between the brake pedal assembly and the master cylinder assembly. The braking force is generated entirely by the electric drive assembly, not by the driver pressing the brake pedal. In other words, the brake-by-wire system operates with full electric drive, not electric power assistance. During this process, the brake pedal and its connected pedal push rod serve only as the brake electronic signal input mechanism, not as the braking force input mechanism. The full electric drive method can improve the response speed and stability of the braking system and enable more precise control of the driving force.

[0030] Furthermore, the electric drive mechanism of the wire control brake coaxially sleeves the electric drive mechanism and the transmission mechanism on the outer periphery of the pedal push rod, and sets a rotating component to rotate synchronously with the rotor of the electric drive mechanism. The rotating component is coaxially sleeved on the outer periphery of the pedal push rod, and a linear pushing component is directly connected to the rotating component. The rotating component coaxially converts the rotational motion into linear motion to push the first brake piston. There is no need to set a gear combination in the middle to perform radial position transmission switching. This not only reduces the size of the brake, but also streamlines the combination configuration of the transmission components, reduces transmission losses, and further improves the kinetic energy recovery rate while reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the installation position of a wire control brake provided in an embodiment of the present application;

[0032] Figure 2 A schematic diagram of a wire control brake provided in an embodiment of the present application;

[0033] Figure 3 A schematic perspective view of an embodiment of a wire control brake provided in an embodiment of the present application;

[0034] Figure 4 Based on Figure 3 a schematic cross-sectional view of the provided brake-by-wire system;

[0035] FIG5( a ) is a schematic diagram of the relative positions of the pedal push rod and the first brake piston in the initial state of the wire control brake provided by an embodiment of the present application;

[0036] FIG5( b ) is a schematic diagram of the dead center position of the first brake piston at the initial propulsion stroke in the energy recovery braking mode of the wire control brake provided by an embodiment of the present application;

[0037] Figure 6 Based on Figure 3 A cross-sectional schematic diagram of another embodiment of the provided wire control brake;

[0038] Figure 7 A schematic flow chart of a braking control method provided in this application. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in this field based on these embodiments are all within the scope of protection of the present invention.

[0040] It should be understood that, in the present application, the terms "front", "rear", "inside", "outside", "top", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present technical solution and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present technical solution.

[0041] Please refer to Figures 1 to 4 As shown, the present invention provides a direct-drive, mechanically decoupled brake-by-wire 100 (hereinafter referred to as brake-by-wire 100), which is applied to vehicle braking, preferably electric vehicles. The brake-by-wire 100 is a fully electric mechanism, where human power is not used as the braking force of the braking system. It has a high kinetic energy recovery rate, thereby increasing the vehicle's range, and has good integration and miniaturization effects.

[0042] The brake-by-wire system 100 includes a master cylinder assembly 10, a brake pedal assembly 20, an electric drive assembly 30, and an electronic control unit 40. Each of these components is connected to the ECU 40, which uses sensors to collect data, process information, and control execution, achieving precise coordination and management of multiple vehicle systems and their actuators. The output of the master cylinder assembly 10 is connected to the wheel brakes via hydraulic lines, forming a braking system.

[0043] Combine Figures 2 to 4As shown, the brake master cylinder assembly 10 includes a brake master cylinder 11 and a brake oil reservoir 14 for supplying brake fluid. The brake master cylinder 11 is configured as a dual-chamber brake master cylinder, enabling independent control of the braking force on the vehicle's front and rear wheels. Specifically, the brake master cylinder 11 is equipped with independent first and second hydraulic chambers 110, 120. A first brake piston 111 is sealingly and slidably connected to the rear end of the first hydraulic chamber 110, and a first spring 112 is disposed within the first hydraulic chamber 110. Furthermore, a second brake piston 121, sealingly and slidably connected within the brake master cylinder 11, separates the first hydraulic chamber 110 from the second hydraulic chamber 120. A second spring 122 is disposed within the second hydraulic chamber 120.

[0044] A first oil pipe 131 is configured on the top of the brake master cylinder 11 to connect the first hydraulic chamber 110 to the brake oil pot 14, a second oil pipe 132 is configured to connect the second chamber 120 to the brake oil pot 14, and a rubber sealing ring 141 is configured at the oil pipe interface to prevent leakage.

[0045] The brake pedal assembly 20 includes a brake pedal 21, a pedal push rod 23, a pedal connecting rod 22, a pedal force simulator 24, and a first sensor 25. The ends of the pedal connecting rod 22 are rotationally connected to the brake pedal 21 and the pedal push rod 23, respectively. The pedal force simulator 24 can quickly and accurately detect the driver's braking intention under zero or limited displacement conditions, and convert a mechanical signal matching the braking intention into an electrical signal, which is then transmitted to the vehicle's electronic control unit 40. The first sensor 25 is used to monitor the motion state of the pedal push rod 23 and transmit real-time data on the motion state of the pedal push rod 23 to the electronic control unit 40 in the form of an electrical signal. The motion state data of the pedal push rod 23 includes at least the displacement and velocity of the pedal push rod 23.

[0046] In one embodiment, the pedal force simulator 24 includes an elastic component, a sensor, a limiter, etc. Through the design of the elastic component and the limiter, a real braking feeling is simulated and the maximum travel of the elastic component is limited to ensure the stability and reliability of the braking effect. Figure 3 and Figure 4As shown, the pedal force simulator 24 preferably features a two-stage spring design to provide a richer feedback effect through varying spring stiffness and damping. Specifically, the pedal force simulator 24 includes a first-stage spring 241, a second-stage spring 242, and a stopper 243. The second-stage spring 242 is mounted around the rear end of the pedal push rod 23. The front end of the second-stage spring 241 is restrained by the rear end cap of the hollow motor 31, and the rear end of the second-stage spring 242 is restrained in front of the stopper 243. The stopper 243 is mounted around the outer periphery of the connection between the pedal push rod 23 and the pedal connecting rod 22, with the first-stage spring 241 positioned within the stopper 243. During pedal braking, the first-stage spring 241, the second-stage spring 242, and the stopper 243 are compressed sequentially, simulating multiple pedal force-travel curves with varying slopes.

[0047] The electric drive assembly 30 comprises a hollow motor 31 and a transmission mechanism 32 coaxially disposed within the hollow motor 31. In this embodiment, the hollow motor 31 comprises a housing 311, a stator (not shown) disposed within the housing 311, and a cylindrical rotor 312. The transmission mechanism 32 comprises a rotating member 321, a linear actuator 322 in transmission connection with the rotating member 321, and a return spring 323 for returning the linear actuator 322 to its original position when power is lost. The linear actuator 322 is used to convert rotational motion into linear motion.

[0048] The master cylinder 11 is coaxially mounted on the front end of the pedal push rod 23, which faces the first brake piston 111. In this embodiment, the electric drive assembly 30 is disposed between the master cylinder assembly 10 and the brake pedal assembly 20 and is coaxially sleeved around the outer circumference of the pedal push rod 23. Specifically, a rotating component 321 is coaxially sleeved around the outer circumference of the pedal push rod 23 and coaxially mounted inside the cylindrical rotor 312. Rotating component 321 is fixedly connected to rotor 312 through a method such as an interference fit or press-fit connection, so that the rotor 312 synchronously drives the rotating component 321 to rotate. Furthermore, a linear actuator 322 is rollingly coupled to the outer circumference of the rotating component 321 and is also radially disposed on the inner circumference of the rotor 312.

[0049] In one embodiment, the transmission mechanism 32 is preferably a ball screw transmission mechanism. The ball screw transmission mechanism is mainly composed of a screw and a nut. The screw is provided with a spiral groove, and the nut is internally provided with balls that can roll along the spiral groove. When the screw rotates relative to the nut, the rotation of the screw causes the balls to push the nut axially. At the same time, the balls roll along the spiral groove, replacing sliding friction with rolling friction. Compared with the meshing transmission of gears, it has lower friction resistance, thereby reducing the transmission loss caused by transmission through gear transmission. When the ball screw transmission mechanism is applied to the transmission mechanism 32 of this embodiment, the rotating component 321 is a screw, and the linear driving component 322 is a nut with a built-in ball. The transmission force of the rotor 312 of the hollow motor 31 is directly transmitted and output through the ball screw transmission mechanism.

[0050] In other alternative embodiments, the electric drive mechanism can also be formed by other component structures, which only needs to be equipped with a rotor 312 with a space for coaxially accommodating the transmission mechanism 32 and capable of synchronously transmitting the transmission mechanism 32. The driving method of the rotor 312 is not limited to driving by electromagnetic induction.

[0051] The pushing end of the linear pushing component 322 abuts against the first brake piston 111 . When the hollow motor 31 drives the linear pushing component 322 forward, the linear pushing component 322 pushes the first brake piston 111 forward, thereby compressing the volume of the first chamber 110 .

[0052] In one embodiment, the brake master cylinder 11 can use a pre-made master cylinder currently available on the market to reduce costs, or can be integrated with the housing 311 of the hollow motor 31 to further simplify the structure.

[0053] In this embodiment, in the initial state of the brake-by-wire system 100, the pedal pushrod 23 and the first brake piston 111 are mechanically separated. Specifically, an initial gap S0 is defined between the pedal pushrod 23 and the first brake piston 111, and the pushing end of the linear push member 322 abuts the first brake piston. In both regenerative braking mode and normal braking mode, the pedal pushrod 23 and the first brake piston 111 remain mechanically separated, with only the linear push member 322 pushing the first brake piston 111 forward. In other words, in both the initial state and regenerative braking mode, the pedal pushrod 23 and the first brake piston 111 are dynamically mechanically decoupled, allowing for more travel in regenerative braking mode and improving kinetic energy recovery. Furthermore, in normal braking mode, the pedal pushrod 23 and the first brake piston 111 remain dynamically mechanically decoupled, with braking performed using a fully electric drive mechanism. This improves the responsiveness and stability of the braking system and enables more precise control of driving force.

[0054] In one embodiment, the initial gap S0 is preferably in the range of 6 to 10 mm, which provides sufficient travel space for the pedal push rod 23 , thereby improving the kinetic energy recovery range of the vehicle.

[0055] Ginseng Figure 6 As shown, in one embodiment, the electric drive assembly 30 is further configured with a second sensor 313 for monitoring the motion state of the rotating member 321. For example, the second sensor 313 is fixedly connected to the outer periphery of the rotating member 312 and located at the rear end of the linear propulsion member 322 to avoid interfering with the linear reciprocating motion of the linear propulsion member 322. The second sensor 313 is in communication with the electronic control unit 40 and feeds back real-time monitored motion state data of the rotating member 321 to the electronic control unit 40. The motion state data of the rotating member 321 includes at least the rotational speed and rotation angle of the rotating member 321.

[0056] Combine Figure 7 As shown, for the wire control brake 100 provided in this embodiment, a braking control method is also provided, including steps S1 to S5:

[0057] Step S1 . Preset a push rod critical stroke St1 for the pedal push rod 23 . The push rod critical stroke St1 is set to be smaller than an initial gap S0 between the pedal push rod 23 and the first brake piston 111 .

[0058] In this embodiment, combined with Figure 2 、 Figure 4 As shown in FIG. 5( a ), in the initial state, an initial gap S0 is provided between the pedal push rod 23 and the first brake piston 111 , and the initial gap S0 is in the range of 6 to 10 mm.

[0059] The brake pedal 21 is configured with a pedal idle travel. This provides an initial tactile sensation when the driver's foot contacts the brake pedal 21. Within this tactile range, the braking system does not apply braking action. In this embodiment, the pedal idle travel is preferably set within a range of 10-20 mm. Due to the presence of the pedal lever, the idle travel of the pedal push rod 23 corresponding to the pedal idle travel is defined as push rod idle travel St0, which ranges from 3-6 mm.

[0060] On this basis, a critical push rod stroke St1 is preset for the pedal push rod 23. The critical push rod stroke St1 is set to be less than the initial gap S0 and equal to or greater than the push rod idle stroke St0, that is, St0≤St1<S0. In a preferred embodiment, the critical push rod stroke St1 is set to be equal to the push rod idle stroke St0, that is, St1=St0.

[0061] Step S2: Determine whether the pedal push rod reaches the critical rod stroke St1.

[0062] The pedal push rod sensor 25 monitors the motion state of the pedal push rod 23 in real time and feeds back the motion state parameters of the pedal push rod 23 to the electronic control unit 40, wherein the motion state parameters of the pedal push rod 23 include parameters such as the displacement and speed of the pedal push rod 23.

[0063] The electronic control unit 40 determines whether the pedal push rod has reached the critical stroke St1. If so, step S3 is executed; if not, step S5 is executed.

[0064] Step S3. The braking system determines whether to execute the energy recovery braking mode based on the comprehensive conditions of the vehicle. If so, execute step S4.

[0065] If the pedal push rod sensor 25 detects that the pedal push rod 23 is pushed and its forward displacement reaches the push rod critical stroke St1, the braking system determines whether to execute the energy recovery braking mode according to the comprehensive situation of the vehicle.

[0066] When the driver brakes, the brake pedal 21 is depressed, and the pedal connecting rod 22 pushes the pedal push rod 23 forward. A magnet 250, which is connected to the pedal push rod 23 and matches the first sensor 25, is connected to the pedal push rod 23. As the magnet 250 moves with the pedal push rod 23, the first sensor 25 sends a displacement signal to the electronic control unit 40. The electronic control unit 40 uses this push rod displacement signal and other vehicle signals to determine which braking mode to use. In this embodiment, the braking system configuration includes at least the following four braking modes:

[0067] Mode 1, energy recovery braking mode

[0068] When the driver initially depresses the brake pedal 21, the brake-by-wire system 100 generates no braking force at all. At this point, the vehicle's deceleration is entirely generated by the reverse power generation of the vehicle's drive motor, and the kinetic energy from the vehicle's deceleration is completely used to generate electricity and stored in the vehicle's power battery. This is compared to a non-decoupled braking system, where the brake must be used to decelerate the vehicle after the driver depresses the brake pedal, wasting kinetic energy. Furthermore, because the brake-by-wire system 100 provided in this embodiment has a larger dynamic decoupling gap between the pedal push rod 23 and the first brake piston 111 in energy recovery braking mode, it can improve the vehicle's kinetic energy recovery rate and increase the vehicle's range.

[0069] Mode 2, normal braking mode

[0070] The electronic control unit 40 calculates the target braking force to be provided, and the electric drive assembly 30 operates to provide the target braking force. The transmission mechanism 32 pushes the first brake piston 111 forward. The first brake piston 111, driven by the first spring 112 and the hydraulic pressure within the first hydraulic chamber 110, pushes the second brake piston 121 forward. The first brake piston 111 outputs two braking pressures through the first and second hydraulic chambers 110 and 120. During this process, a gap is always maintained between the pedal push rod 23 and the first brake piston 111. This means that the brake pedal 21 never directly pushes the first brake piston 111. The braking action is entirely driven by the hollow motor 31.

[0071] Mode 3, emergency braking mode

[0072] If a critical system failure occurs (e.g., a power outage), emergency mechanical braking is performed manually. By rapidly depressing the brake pedal 21, the pedal push rod 23 moves forward, eliminating the initial gap S0 between the pedal push rod 23 and the first brake piston 111. The pedal push rod 23 then pushes the first and second brake pistons 111, 121 forward, outputting two brake pressures. During this process, the hollow motor 31 does not operate, and the braking action is entirely generated by the driver's force applied to the brake pedal 21.

[0073] Mode 4, external braking mode

[0074] The electronic control unit 40 receives a braking request from the outside, controls the hollow motor 31 to work, and the transmission mechanism 32 pushes the first brake piston 111 forward. The first brake piston 111 pushes the second brake piston 121 forward through the first spring 112 and the hydraulic pressure in the first hydraulic chamber 110 and outputs two braking pressures to the outside through the first hydraulic chamber 110 and the second hydraulic chamber 120; during this process, the driver does not step on the brake pedal 21, and the brake pedal 21, pedal connecting rod 22, pedal push rod 23, and pedal force simulator 24 are all not working.

[0075] Step S4 : The electronic control unit 40 controls the electric drive assembly 30 to operate, and the linear propulsion component 322 pushes the first brake piston 111 forward.

[0076] Combine Figure 1 、 Figure 2 、 Figure 4 As shown in FIG5(b), in the hydraulic line connecting the master cylinder 11 to the wheel brake, due to the normal working stroke of the wheel brake and the expansion of the brake hose, there is a brake system idle stroke Sx in the early stage of hydraulic braking.

[0077] In this embodiment, an initial thrust stroke S1 is preset for the first brake piston 111, and this stroke is set to be less than the idle stroke Sx of the brake system, i.e., S1 < Sx. This allows the first brake piston 111 to move forward a considerable distance under the drive of the electric drive assembly 30, dynamically increasing the decoupling clearance between the first brake piston 111 and the pedal push rod 23. The preset initial thrust stroke S1 for the first brake piston 111 is preferably no greater than 12 mm, i.e., S1 ≤ 12 mm. In a preferred embodiment, the preset initial thrust stroke S1 for the first brake piston 111 is preferably within a range of 8 to 12 mm, i.e., S1 = 8 to 12 mm.

[0078] If the braking system enters regenerative braking mode, when the first sensor 25 detects that the pedal push rod 23 has been pushed and its displacement exceeds the push rod's critical travel St1, the electronic control unit 40 controls the electric drive assembly 30, causing the linear push component 322 to advance the first brake piston 111. The distance S2 traveled by the linear push component 322 is the distance S2 of the first brake piston 111. When S2 ≤ S1, the forward movement of the first brake piston 111 increases the decoupling gap behind it, increasing from S0 to S0 + S2. This increased decoupling gap provides sufficient travel space for the pedal push rod 23, thereby improving the vehicle's kinetic energy recovery range. Furthermore, within this travel space, since the pedal push rod 23 never contacts the first brake piston 111, the resistance experienced by the driver when depressing the pedal does not change abruptly, maintaining a linear pedal feel.

[0079] During this process, the hydraulic oil output by the master cylinder 11 is used to push the wheel cylinder pistons and expand the brake hoses, and is not used for braking the wheel brakes. Only when the decoupling gap S0+S2 is gradually reduced to zero by manual force on the pedal push rod 23, and the stroke of the first brake piston 111 jointly pushed by the linear push member 322 and the manual force exceeds the range of the initial propulsion stroke S1, that is, exceeds the dead center position of the initial propulsion stroke S1 of the first brake piston 111 shown in Figure 5(b), does the hydraulic oil output by the master cylinder 11 begin to be used for braking the wheel brakes. In other words, the brake system begins to participate in the vehicle's deceleration, and a portion of the vehicle's deceleration kinetic energy begins to be converted into brake system heat energy.

[0080] In one embodiment, the rotation speed and angle of the rotating component 321 can be monitored in real time by the second sensor 313. Not only can they be calculated with the preset output motion state parameters of the hollow motor 31 and the input parameters of the hollow motor 31 be adjusted when the error range is exceeded, but the motion state parameters actually output by the hollow motor 31 can also be monitored in real time for fault detection and protection.

[0081] Furthermore, the motion parameters of the rotating part 321 monitored by the second sensor 313 can be calculated with the motion state parameters of the pedal push rod 23 monitored by the first sensor 25. If they exceed the preset error range, the input parameters of the hollow motor 31 are adjusted to limit the error to the preset error range.

[0082] Step S5: The braking system does not perform any braking action.

[0083] When the pedal push rod sensor 25 detects that the pedal push rod 23 is pushed and its pushed displacement is within the range of the push rod idle stroke St0, the braking system does not perform a braking action; when the pedal push rod sensor 25 detects that the pedal push rod 23 is pushed and its forward displacement is within the range of the push rod critical stroke St1, the braking system does not perform a braking action either.

[0084] Currently, hydraulic wire-controlled brakes on the market, such as Bosch IPB, have no upper limit on the braking deceleration that can recover 100% of the kinetic energy. Mechanical wire-controlled brakes, such as Nason NBooster, have an upper limit of about 0.3 to 0.4G, where G represents the acceleration due to gravity. However, regardless of the type of wire-controlled brake, the braking deceleration of a vehicle that recovers 100% of its kinetic energy in commercial applications is generally within 0.4G. The wire-controlled brake 100 provided in this application can achieve a braking deceleration with 100% kinetic energy recovery, with an upper limit of between 0.35 and 1.0G depending on the vehicle model, which can fully meet the needs of commercial applications. And on this basis, the wire-controlled brake 100 provided in this application greatly simplifies the structure and reduces costs.

[0085] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0086] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0087] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A direct-drive mechanically decoupled brake-by-wire system, comprising a master cylinder assembly, a brake pedal assembly, an electric drive assembly, and an electronic control unit, wherein the master cylinder assembly, the brake pedal assembly, and the electric drive assembly are respectively connected to the electronic control unit for communication, characterized in that: The master cylinder assembly includes a first brake piston, the brake pedal assembly includes a pedal push rod and a first sensor for monitoring the movement state of the pedal push rod, and an initial gap is provided between a pushing end of the pedal push rod and the first brake piston; The electric drive assembly includes an electric drive mechanism and a transmission mechanism coaxially sleeved on the outer periphery of the pedal push rod, the electric drive mechanism having a rotor, the transmission mechanism including a rotating component and a linear pushing component transmission-connected to the rotating component, the transmission mechanism being disposed inside the electric drive mechanism and the rotating component rotating synchronously with the rotor, the rotating component coaxially sleeved on the outer periphery of the pedal push rod, and the pushing end of the linear pushing component abutting against the first brake piston; In an initial state, an energy recovery braking mode, and a normal braking mode, the pedal push rod and the first brake piston are mechanically decoupled.

2. The direct-drive mechanical decoupling brake-by-wire according to claim 1, characterized in that: In an initial state, the initial gap between the pushing end of the pedal push rod and the first brake piston is configured to be in a range of 6 to 10 mm.

3. The direct-drive mechanical decoupling brake-by-wire according to claim 1, characterized in that: A critical stroke of the push rod is set for the brake push rod, and the critical stroke of the push rod is smaller than the initial gap. When the first sensor detects that the forward displacement of the pedal push rod exceeds the critical stroke of the push rod, the electronic control unit controls the operation of the electric drive assembly, and the linear propulsion component pushes the first brake piston forward.

4. The direct-drive mechanical decoupling brake-by-wire according to claim 1, characterized in that: The driving element of the electric drive assembly is a hollow motor, the rotor of the hollow motor is configured in a cylindrical shape, and the rotating component is arranged on the inner circumference of the rotor and is connected to the rotor in synchronous rotation.

5. The direct-drive mechanical decoupling brake-by-wire according to claim 4, characterized in that: The rotating component is a screw, the linear pushing component is a nut with a built-in ball, and the linear pushing component is in rolling connection with the rotating component.

6. The direct-drive mechanically decoupled brake-by-wire according to claim 1, characterized in that: The electric drive assembly is configured with a second sensor for monitoring the motion state of the rotating component. The motion state data of the rotating component at least includes a rotation speed and a rotation angle. The second sensor is in communication with the electronic control unit.

7. The direct-drive mechanical decoupling brake-by-wire according to claim 1, characterized in that: The brake pedal assembly is also equipped with a pedal connecting rod and a pedal force simulator. The pedal connecting rod is rotatably connected to the pedal push rod. The pedal force simulator includes a first-stage spring, a second-stage spring and a limiter. The second-stage spring is sleeved on the outer periphery of the rear end of the pedal push rod. The front end of the second-stage spring is limited to the rear end of the electric drive assembly. The rear end of the first-stage spring is limited to the front side of the limiter. The limiter is sleeved on the outer periphery of the connection between the pedal push rod and the pedal connecting rod, and the first-stage spring is arranged inside the limiter.

8. A braking control method, applied to a braking system, characterized in that: The braking system comprises a brake according to any one of claims 1 to 7, and the braking control method comprises: Presetting a push rod critical stroke for the pedal push rod, wherein the push rod critical stroke is set to be smaller than an initial gap between the pedal push rod and the first brake piston; Determining whether the forward displacement of the pedal push rod reaches the push rod critical stroke; If so, the braking system determines whether to execute the energy recovery braking mode based on the comprehensive conditions of the vehicle; When the energy recovery braking mode is executed, the electronic control unit controls the electric drive assembly to operate, and the linear propulsion component pushes the first brake piston forward.

9. The brake control method according to claim 8, characterized in that: The braking system has a braking system idle stroke. For the energy recovery braking mode, the first brake piston is preset with an initial propulsion stroke, and the initial propulsion stroke is preset to be smaller than the braking system idle stroke. When the stroke of the first brake piston propulsed by the linear propulsion component is within the range of the initial propulsion stroke, the decoupling gap between the pedal push rod and the first brake piston dynamically increases.

10. The brake control method according to claim 8, characterized in that: The electric drive component is configured with a second sensor for monitoring the motion state of the rotating part. The braking control method also includes: when judging whether the forward displacement of the pedal push rod reaches the critical stroke of the push rod, the motion state data of the rotating part monitored by the second sensor and the motion state data of the pedal push rod monitored by the first sensor are calculated. If it exceeds a preset error range, the input parameters of the electric drive component are adjusted to limit the error to within the preset error range.

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