Hybrid brake system and vehicle including the same

Abstract

Embodiments of the present disclosure relate to a hybrid brake system. The hybrid brake system includes an electromechanical brake and a hydraulic system. The electromechanical brake includes: a caliper body; an actuating mechanism, a driven mechanism moving back and forth in a first direction, and a piston. A first cavity is formed between the side, away from the piston, of the driven mechanism and the caliper body, and a second cavity is formed between the moving mechanism and the piston. The hydraulic system comprises a brake fluid supply unit; a first hydraulic line connected with the first chamber via the first through hole; and a second hydraulic line connected to the second chamber via the second through-hole; brake fluid flows unidirectionally from the first chamber to the second chamber. By means of the hybrid braking system, large braking force can be provided by means of the hydraulic system under the condition that the size and cost are not increased, and the vehicle can work in multiple braking modes.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of electric vehicles, and more particularly to a hybrid braking system of an electromechanical brake and a hydraulic brake for a vehicle and a vehicle including the hybrid braking system. Background Art

[0002] The future braking systems of electric vehicles generally include dry-dry architectures and dry-wet architectures. In the dry-dry architecture, the electromechanical brakes (EMB) of the two front wheels of the electric vehicle achieve a larger clamping force on the brake disc, while the EMBs of the two rear wheels achieve a smaller clamping force on the brake disc. In this case, the size of the EMB components of the front wheels is larger than the size of the EMB components of the rear wheels, so the cost is also higher. In the dry-wet architecture, the front wheels of the electric vehicle use hydraulic brakes to achieve a larger clamping force, while the rear wheels use EMBs to achieve a smaller clamping force. Whether using a dry-dry architecture or a dry-wet architecture, there are problems such as it is difficult to further increase the clamping force or the cost is high. Therefore, there is a need to improve the braking system of electric vehicles. Summary of the Invention

[0003] Embodiments of the present disclosure provide a hybrid braking system and a vehicle including the hybrid braking system.

[0004] According to a first aspect of the present disclosure, a hybrid braking system is provided. The hybrid braking system includes an electromechanical brake and a hydraulic system. The electromechanical brake includes: a caliper body; a driven mechanism located within the caliper body and capable of being actuated to move back and forth in a first direction; and a piston, wherein a first side of the piston in the first direction faces the driven mechanism, and a second side of the piston in the first direction is located outside the caliper body, wherein a first chamber is formed between a side of the driven mechanism away from the piston and the caliper body, and a second chamber is formed between the driven mechanism and the piston. The hydraulic system includes: a brake fluid supply unit; a first hydraulic line connected to the brake fluid supply unit and connected to the first chamber via a first through-hole passing through the caliper body so that the first chamber is filled with brake fluid; and a second hydraulic line connected to the brake fluid supply unit and connected to the second chamber via a second through-hole passing through the caliper body so that the second chamber is filled with brake fluid; wherein the electromechanical brake is configured so that the brake fluid can flow unidirectionally from the first chamber to the second chamber.

[0005] According to a second aspect of the present disclosure, a vehicle is provided, comprising: a plurality of wheels, wherein at least a front left wheel and a front right wheel of the plurality of wheels are provided with the hybrid braking system according to the first aspect of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0007] Figure 1 A schematic diagram illustrating an example environment to which some embodiments of the present disclosure are applicable;

[0008] Figure 2 A cross-sectional view of an electromechanical brake according to an embodiment of the present disclosure is illustrated, wherein the brake is a floating caliper;

[0009] Figure 3 The figure shows a structural diagram of the hydraulic system of an embodiment of the present disclosure and a working principle diagram of a pure EMB braking mode;

[0010] Figure 4 FIG2 illustrates a working principle diagram of an embodiment of the present disclosure under a boost condition in a hybrid braking mode;

[0011] Figure 5 FIG2 illustrates a working principle diagram of an embodiment of the present disclosure in a pressure-maintaining condition in a hybrid braking mode;

[0012] Figure 6 FIG2 illustrates a working principle diagram of a decompression condition in a hybrid braking mode according to an embodiment of the present disclosure;

[0013] Figure 7 FIG2 illustrates a working principle diagram of an embodiment of the present disclosure in HCA degradation mode (third type of fault);

[0014] Figure 8 illustrates a cross-sectional view of an electromechanical brake according to an embodiment of the present disclosure, wherein the brake is a fixed caliper; and

[0015] Figure 9 FIG2 illustrates a working principle diagram of a brake fluid circulation mode according to an embodiment of the present disclosure.

[0016] In the various drawings, the same or corresponding reference numerals denote the same or corresponding parts. DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure. The embodiments of the present disclosure described below with reference to the accompanying drawings are for illustrative purposes only.

[0018] An electromechanical brake (EMB) typically consists of an electronic control unit (ECU), a motor, a reduction gear, a motion conversion mechanism (e.g., a ball screw and nut that converts rotational motion into linear motion; the rotational motion component is called the actuator, and the linear motion component is called the driven mechanism), a piston connected to the driven mechanism to restrict its rotation, a friction plate connected to the piston (located on the side away from the driven mechanism), and a brake caliper housing the motion conversion mechanism, piston, and friction plate. The ECU continuously controls the torque and speed of the motor by controlling the amount and duration of current supplied to the motor. The reduction gear converts the motor's high-speed rotational motion into low-speed rotational motion to increase output torque. The motion conversion mechanism converts the rotational motion transmitted from the motor shaft and reduction gear to the actuator (e.g., the ball screw) into linear motion of the driven mechanism (e.g., the nut), enabling the piston to push the friction plate, thereby clamping the brake disc, or release the thrust on the friction plate, thereby releasing the brake disc. When the friction plate is pushed to clamp the brake disc, the vehicle can be decelerated or stopped. Conversely, when the thrust on the friction plate is released to release the brake disc, the vehicle can be stopped from being decelerated or stopped.

[0019] As described above, during braking to decelerate a vehicle, the front wheels require greater clamping force on the brake discs than the rear wheels. Therefore, the front wheels typically require larger EMBs. Larger EMBs typically include larger motors, larger reduction gears, and larger motion conversion mechanisms. However, due to the limited space available on existing front axles for front-wheel steering, there's insufficient room to install a larger EMB.

[0020] Furthermore, braking on a uniform road surface requires equal braking force on both wheels, otherwise the vehicle may twist or turn unexpectedly. Therefore, it is necessary to monitor the braking force of the left and right wheels in real time as a feedback signal for the closed-loop control of the clamping force of the left and right EMBs. Specifically, at least one clamping force sensor must be installed on each of the left and right EMBs. This clamping force sensor typically consists of a force-sensitive element (such as an elastomer), a conversion element (such as a resistance strain gauge), and a circuit. It can withstand high and low temperatures and high-intensity vibration and shock conditions. Therefore, it is relatively expensive and requires a certain amount of installation space to be reserved in the EMB.

[0021] Furthermore, the friction pads on the EMB wear out over time. Therefore, when designing the EMB, it's crucial to ensure that the vehicle's braking performance and safety are maintained even after the pads have worn out. This means that the motion conversion mechanism (e.g., the ball screw and nut) must be designed with a certain amount of travel margin to compensate for the maximum allowable wear of the friction pads. This results in a complex and bulky design for the motion conversion mechanism.

[0022] In addition, under the anti-lock braking condition of the wheel, when the friction plate of the EMB clamps the brake disc of the wheel and reaches critical locking, due to the inertia of the mechanical moving parts inside the EMB (for example, the ball screw and nut), the friction plate cannot release the brake disc with the fastest response speed, and there is a delayed release of the brake disc, which affects the performance of the anti-lock braking of the wheel.

[0023] Therefore, an embodiment of the present disclosure provides a hybrid braking system, which mainly includes an electric mechanical brake (EMB) installed at the wheel end and a hydraulic system (HCA) installed at the non-wheel end. When the braking system is operating normally, the EMB can be used alone to provide a medium-intensity braking force or less, i.e., a pure EMB braking mode (most braking belongs to this mode), or the EMB and HCA can form a combined force to provide a high-intensity braking force, i.e., a hybrid braking mode (a small part of the braking belongs to this mode). Therefore, under the condition of meeting the same maximum workload, the volume and weight of the EMB of the hybrid braking system are greatly reduced compared to the traditional EMB, which is conducive to the arrangement of the EMB at the wheel end, especially at the front wheel end where space is limited. In addition, since the HCA can be flexibly installed in various locations at the non-wheel end (e.g., the engine compartment), it is not restricted by the space at the narrow wheel end. Furthermore, in the event of a brake system failure, such as an EMB failure, the HCA alone can provide backup braking force to meet regulatory requirements (this is known as HCA backup mode). Furthermore, in the event of an HCA failure, the EMB alone can provide braking force to meet regulatory requirements (this is known as HCA degraded mode). This demonstrates that the EMB and HCA can serve as mutual backups to meet both regulatory and driver safety requirements. Furthermore, for the following two operating conditions: if air enters the brake system's hydraulic lines or the brake pads overheat, the hybrid brake system's brake fluid circulation circuit can be used to automatically vent the hydraulic lines and accelerate heat dissipation from the friction pads (this is known as brake fluid circulation mode).

[0024] The following will refer to Figure 1 Schematic diagram of an example environment to which some embodiments of the present disclosure are applicable. Figure 1 The present invention shows a braking system suitable for an electric vehicle according to some embodiments of the present invention. Figure 1 A braking system suitable for an electric vehicle is described, but the braking system is also suitable for other types of vehicles.

[0025] like Figure 1As shown, hybrid braking system 100 includes a brake pedal 101, which can be depressed by a user; a pedal force sensor (PFS) 102, which senses the force applied by the user; and a pedal travel sensor (PTS) 103, which senses the distance traveled by the user while depressing the brake pedal. Optionally, the braking system also includes a pedal feel simulator 104, which provides user feedback on brake pedal force and travel, ensuring that the user is properly depressing the brake pedal. For PFS 102, the braking system includes two power supply and communication lines 102-1 and 102-2; for PTS 103, the braking system also includes two power supply and communication lines 103-1 and 103-2. The first power supply and communication lines 102 - 1 and 103 - 1 are both connected to the electronic control unit 201 of the hydraulic system 200 , while the second power supply and communication lines 102 - 2 and 103 - 2 are both connected to the vehicle chassis domain electronic control system 105 . Figure 1 Each power supply and communication line has three pins, which represent the signal pin, power pin and ground pin respectively.

[0026] The vehicle chassis domain electronic control system 105 includes at least two communication systems, which are connected to the electronic control unit (ECU) 201 of the hydraulic system 200 and the electronic control unit (ECU) 301 of the electromechanical brake 300 through a first communication bus 105-1 and a second communication bus 105-2 respectively.

[0027] The electronic control unit 201 of the hydraulic system 200, the electronic control unit 301 of the electromechanical brake 300, and the vehicle chassis domain electronic control system 105 send and receive signals to and from each other via communication buses 105-1 and 105-2. In the event of a failure in the first communication bus 105-1, signals between the electronic control units can be sent and received via the second communication bus 105-2, and vice versa. This provides redundancy in the brake system's communication system, increasing system stability and reliability.

[0028] According to the hybrid braking system 100 of the present disclosure, the two front wheels of the vehicle are equipped with a hydraulic system 200 and wet (with brake fluid) electromechanical brakes 300, while the two rear wheels of the vehicle are equipped with only dry (without brake fluid) electromechanical brakes. Because the braking force required by the rear wheels is smaller than that of the front wheels, the additional clamping force support of the hydraulic unit is not required. However, the present disclosure is not limited to this, and the hybrid braking system 100 of the present disclosure can be used on all four front and rear wheels of the vehicle.

[0029] In the hybrid brake system 100 according to the present disclosure, brake fluid from the hydraulic system 200 is supplied to the electromechanical brake 300 via the inlet line or first hydraulic line 41 in hybrid braking mode, HCA backup mode, or brake fluid circulation mode, thereby providing additional clamping force support for the electromechanical brake 300. Furthermore, the brake fluid within the electromechanical brake 300 is returned to the hydraulic system 200 via the outlet line or second hydraulic line 42 in hybrid braking mode or brake fluid circulation mode, thereby adjusting the clamping force of the electromechanical brake 300, removing air from the brake, or reducing its temperature. Compared to a clamping force provided solely by the electromechanical brake 300, the hybrid brake system 100 according to the present disclosure can provide greater clamping force.

[0030] The following will refer to Figure 2 The exemplary structure of the electromechanical brake 300 according to the embodiment of the present disclosure will be described in detail. Figure 2 The EMB 300 is described with reference to a floating caliper for the right wheel, but a floating caliper for the left wheel also includes a similar structure.

[0031] like Figure 2 As shown, the electromechanical brake EMB 300 includes: a caliper body 31; and an actuating mechanism 32, such as a rotary ball screw, which can extend through the caliper body 31 to reach the outside of the caliper body 31. Figure 2 As shown, the actuating mechanism 32 is sealed relative to the caliper body by a sealing ring 39c. The EMB 300 further includes a driven mechanism 33, such as a linear motion nut, which is located inside the caliper body 31 and connected to the actuating mechanism 32 to be able to move along the positive and negative directions of the X axis (such as Figure 2 Move back and forth in the right and left directions as shown. Figure 2 As shown, the EMB 300 further includes a first friction plate 34A and a second friction plate 34B, which are located outside the caliper body 31 and on both sides of the brake disc 40 along the X-axis, so that the first friction plate 34A and the second friction plate 34B can clamp the brake disc 40 of the vehicle to brake the vehicle, and conversely can release the brake disc 40 to release the brakes on the vehicle.

[0032] like Figure 2 As shown, the EMB 300 further includes a piston 36, a first side of the piston 36 in the X-axis direction faces the driven mechanism 33 and restricts its rotation, a second side of the piston is located outside the caliper body 31 and connected to the first friction plate 34A, and the second friction plate 34B is connected to the caliper body 31. Figure 2As shown, the floating caliper also includes a first portion 31A and a second portion 31B forming the caliper body 31. A space is defined between the first portion 31A for accommodating the wheel brake disc 40, and the two portions can move back and forth along the X-axis relative to the brake disc 40. Specifically, the actuator mechanism 32, the driven mechanism 33, the piston 36, the sealing rings 39A and 39B, the first friction plate 34A connected to the piston 36, the electronic control unit 301 connected to the first portion 31A, the motor 302, and the speed reduction mechanism 303 located in the first portion 31A move back and forth along the X-axis on one side of the brake disc. The second friction plate 34B, mounted on the second portion 31B, can also move back and forth along the X-axis on the other side of the brake disc. When the piston 36 pushes the first friction plate 34A toward the brake disc 40, the second portion 31B, driven by the first portion 31A in the opposite direction of the piston 36's movement, pushes the second friction plate 34B toward the brake disc 40. Ultimately, the friction plates clamp the brake disc 40, thereby braking the wheel. Conversely, when the piston 36 pulls the first friction plate 34A away from the brake disc 40, the second portion 31B, pushed by the first portion 31A in the direction opposite to the movement of the piston 36, pulls the second friction plate 34B away from the brake disc 40, thereby releasing the brakes on the vehicle. In other words, in a floating caliper, the first portions 31A and 31B of the caliper body 31 cannot move relative to each other, but the second portion 31B can move in conjunction with the movement of the first portion 31A, while the first portion 31A moves in the direction opposite to the movement of the piston 36.

[0033] In an embodiment according to the present disclosure, Figure 2 As shown, the follower mechanism (e.g., nut) 33 is separated from the piston 36. A first chamber 37 filled with brake fluid is formed between the follower mechanism 33 and the caliper body 31. Specifically, the first chamber 37 is formed between the side of the follower mechanism 33 facing away from the piston 36 and the caliper body 31. A second chamber 38 filled with brake fluid and having a variable volume is formed between the follower mechanism 33 and the piston 36. In other words, the follower mechanism 33 and the piston 36 are not fixedly coupled in the X-axis direction but are fixedly coupled in the direction of rotation about the X-axis. The stroke of the follower mechanism 33 is limited to the displacement required to eliminate the gap between the first and second friction plates 34A, 34B and the brake disc 40 and subsequently achieve the clamping force. The stroke of the piston 36, on the other hand, gradually compensates for the wear of the first and second friction plates 34A, 34B until the wear reaches a maximum value. The increase in the volume of the second chamber 38 is compensated by the brake fluid from the first chamber 37.

[0034] like Figure 2As shown, a first through-hole 37t and a second through-hole 38t are formed in the caliper body 31. One end of the first through-hole 37t is connected to the first chamber 37, and the other end thereof is connected to the first hydraulic line 41 of the hydraulic system 200 via a hydraulic pipeline. One end of the second through-hole 38t is connected to the second chamber 38, and the other end thereof is connected to the second hydraulic line 42 of the hydraulic system 200 via a hydraulic pipeline. As a result, the first chamber 37 and the second chamber 38 are filled with brake fluid. It should be noted that under normal braking, the brake fluid in the second chamber 38 does not flow out of the second through-hole 38t. The driven mechanism 33 utilizes the transfer effect of the brake fluid in the second chamber 38 to push the piston 36 toward the brake disc 40.

[0035] like Figure 2 As shown, the EMB 300 also includes a motor 302 and a reduction mechanism 303 (e.g., a gearbox). The motor 302 is controlled by the electronic control unit 301 to output speed and torque. After passing through the reduction mechanism 303, the speed and torque of the motor 302 are reduced and the torque is increased. The low-speed rotational motion is then converted into linear motion via the actuator 32 and the driven mechanism 33, thereby pushing the piston 36. The electronic control unit 301 can receive signals from the vehicle chassis domain electronic control system 105 and the electronic control unit 201 of the hydraulic system 200, or send signals to the latter two via the communication bus 105-1 or 105-2.

[0036] like Figure 2 As shown, a sealing ring 39A, such as a lip seal, is provided between the driven mechanism 33 and the caliper body 31. This sealing ring 39A, for example, is a lip seal. This sealing ring provides one-way isolation between the first chamber 37 and the second chamber 38. That is, brake fluid can only flow from the first chamber 37 to the second chamber 38, but not in the opposite direction. Furthermore, a sealing ring 39C is provided between the portion of the actuating mechanism 32 that passes through the caliper body 31 and the corresponding portion on the caliper body 31. This sealing ring 39C prevents brake fluid in the first chamber 37 from flowing out of the first chamber 37 through the gap between the actuating mechanism 32 and the caliper body 31. A sealing ring 39B is provided between the piston 36 and the caliper body 31. This sealing ring 39B prevents brake fluid in the second chamber 38 from flowing out of the second chamber 38 through the gap between the piston 36 and the caliper body 31. When the vehicle is braked, the piston 36 moves toward the brake disc 40 , and the sealing ring 39B deforms along the positive direction of the X-axis. When the vehicle is braked, the deformation of the sealing ring 39B is restored, thereby driving the piston 36 away from the brake disc 40 .

[0037] like Figure 2As shown, when braking is not in effect, the brake fluid in both first chamber 37 and second chamber 38 is at atmospheric pressure. Due to pressure equalization, the brake fluid in first chamber 37 does not flow into second chamber 38. Furthermore, the brake fluid in second chamber 38 is prevented from flowing into first chamber 37 due to the one-way seal provided by seal ring 39A. In pure EMB braking mode, due to the incompressible nature of fluid, the clamping force from driven mechanism 33 (e.g., nut) is transmitted to piston 36 via the incompressible brake fluid, thereby gradually moving first friction pad 34A closer to brake disc 40. Simultaneously, in the case of a floating caliper, the reaction to this clamping force is transmitted by actuator 32 via planar bearing 35 to first portion 31A, driving second portion 31B in the negative X-axis direction. Pushed by second portion 31B, second friction pad 34B also gradually approaches brake disc 40. Ultimately, first and second friction pads 34A and 34B simultaneously contact and clamp brake disc 40, thereby braking the vehicle. The case of fixed calipers will be described in detail below.

[0038] like Figure 1 and Figure 2 As shown, in the hybrid braking mode, the hybrid braking system 100 according to the present disclosure can pressurize the brake fluid in the first chamber 37 through the hydraulic system 200, so that the brake fluid flows from the first chamber 37 to the second chamber 38, thereby increasing the pressure in the second chamber 38 to the pressure level of the first chamber 37. The hydraulic pressure can further pressurize the piston 36 and further drive the second part 31B, so that the first friction plate 34A and the second friction plate 34B further clamp the brake disc 40, ultimately achieving the goal of increasing the braking force.

[0039] like Figure 1 and Figure 2 As shown, if EMB 300 fails (e.g., the motor fails), that is, in HCA backup mode, actuator 32 is unable to drive follower 33 to generate a clamping force on piston 36. However, hydraulic system 200 allows more brake fluid to flow into first chamber 37 through first hydraulic line 41, pressurizing the brake fluid therein. Because lip seal 39A opens when the pressure in first chamber 37 is higher than that in second chamber 38, brake fluid in first chamber 37 can flow into second chamber 38, where the pressure is lower, increasing the brake fluid pressure in second chamber 38. Consequently, the increased brake fluid in first and second chambers 37, 38, replaces actuator 32 and follower 33 to push piston 36 and drive second portion 31B, thereby moving first and second friction pads 34A and 34B toward brake disc 40, ultimately achieving braking force on the vehicle. In other words, the wet electromechanical brake 300 operates according to the same principle as a conventional floating hydraulic caliper.

[0040] In summary, the hybrid braking system 100 of the present disclosure can not only provide moderate or lower braking forces using only the EMB 300, but can also provide high-intensity braking forces by combining the EMB 300 and the hydraulic system 200. In the event of an EMB 300 failure, the hydraulic system 200 can also provide backup braking forces that meet braking regulations. Therefore, by adding the hydraulic system 200 to assist the EMB 300, high-intensity braking forces can be achieved without increasing the size of the EMB 300's reduction mechanism and motor, thereby facilitating the placement of the EMB 300 at the wheel end, particularly at the front wheel end where space is limited.

[0041] The following will refer to Figure 3 An example structure of a hydraulic system 200 and a pure EMB braking mode according to an embodiment of the present disclosure will be described.

[0042] like Figure 3 As shown, hydraulic system 200 includes a reservoir 203, which includes a first reservoir chamber 203A and a second reservoir chamber 203B. First reservoir chamber 203A provides brake fluid for the hydraulic brake of the left front wheel, while second reservoir chamber 203B provides brake fluid for the hydraulic brake of the right front wheel. First reservoir chamber 203A and second reservoir chamber 203B are separated at the bottom and connected at the top, so that both are at atmospheric pressure and the hydraulic pressure of the left and right front wheels is the same.

[0043] Since the hydraulic subsystems for the left and right front wheels are the same, the following will focus on the various components of the hydraulic system 200 for the right front wheel.

[0044] like Figure 3 As shown, the hydraulic system 200 also includes a control valve 29, one end of which is directly connected to the reservoir 203, and the other end of which is connected to the first chamber 37 through the first through hole 37t. The above-mentioned brake fluid passage from the reservoir 203 to the first through hole 37t is called a first hydraulic pipeline 41.

[0045] like Figure 3 As shown, the hydraulic system 200 also includes a liquid outlet valve 28 and a hydraulic sensor 20. One end of the liquid outlet valve 28 is directly connected to the reservoir 203, and the other end thereof is connected to the second chamber 38 through the second through hole 38t. The above-mentioned brake fluid passage from the reservoir 203 to the second through hole 38t is called a second hydraulic pipeline 42. The hydraulic sensor 20 is arranged between the liquid outlet valve 28 and the second through hole 38t to monitor the brake fluid pressure in the second chamber 38.

[0046] like Figure 3 As shown, the hydraulic system 200 also includes a liquid inlet valve 27, several ( Figure 3 The hydraulic pump 24 (two in the example) is identical, and includes a hydraulic sensor 26 and motor 25. The brake fluid input of the hydraulic pump 24 is directly connected to the reservoir 203, while its output is connected to one end of the inlet valve 27. The other end of the inlet valve 27 is connected to the first chamber 37 via a first through-hole 37t. The brake fluid path from the reservoir 203 to the first through-hole 37t is referred to as the third hydraulic line 23. The hydraulic sensor 26 is positioned between the brake fluid output of the hydraulic pump 24 and the inlet valve 27 to monitor the brake fluid pressure output by the hydraulic pump 24. Since the hydraulic pumps 24 for the left and right front wheels are driven by the same motor 25, the brake fluid pressures output by both are consistent. Therefore, it is preferable to use only one hydraulic sensor 26. However, in alternative embodiments, a pressure sensor can be provided for each of the left and right hydraulic pumps 24.

[0047] In an exemplary embodiment, the hydraulic pump 24 , the motor 25 , the liquid inlet valve 27 , the liquid outlet valve 28 and the control valve 29 are all controlled by the electronic control unit 201 , and the signals of the hydraulic sensors 20 and 26 are fed back to the electronic control unit 201 .

[0048] like Figure 3 As shown, in the pure EMB braking mode, the hydraulic unit 200 is in an inoperative state. The hydraulic pump 24, motor 25, inlet valve 27, control valve 29, and outlet valve 28 are all inoperative under the control of the electronic control unit 201. The inlet valve 27 and control valve 29 are in a normally open state, i.e., they allow brake fluid to flow through them, while the outlet valve 28 is in a normally closed state, preventing the brake fluid from the second chamber 38 from flowing out through the outlet valve 28.

[0049] When only EMB is used for braking, the first chamber 37 is driven by the actuator 32 to drive the driven mechanism 33 along the positive direction of the X1 axis (taking the right front wheel EMB 300 as an example, that is, Figure 3 The left front wheel EMB 300 is displaced in the right direction (as shown, while the left front wheel EMB 300 is in the opposite direction of the X-axis X2), causing displacement and an increase in volume. The hydraulic system 200 replenishes brake fluid in the first chamber 37 via the control valve 29 through the pipeline 21, thereby maintaining the first chamber 37 at atmospheric pressure. The trapped brake fluid in the second chamber 38 is used to transmit the axial force from the driven mechanism 33 to the piston 36. When only the EMB is used to release the brakes, the first chamber 37 decreases in volume due to the actuator 32 driving the driven mechanism 33 in the negative X-axis direction. The hydraulic system 200 absorbs excess brake fluid from the first chamber 37 via the control valve 29, thereby maintaining the first chamber 37 at atmospheric pressure and releasing the pressure of the trapped brake fluid in the second chamber 38.

[0050] Specifically, when the friction plates are not worn and the EMB 300 is not braking, the distance X of the driven mechanism 33 relative to the reference A is X=X0, the distance Y of the piston 36 relative to the reference A is Y=Y0, the gap Z=Z0 between the first and second friction plates 34A and 34B and the brake disc 40 is Z=Z0, and the volume of the second chamber 38 is determined by H=YX=Y0-X0. When the EMB 300 is braking, X=X0+2Z0 and Y=Y0+2Z0. When the friction plates are worn, for example, when the first and second friction plates 34A and 34B are each worn by 0.1 mm, when the EMB 300 applies braking, the driven mechanism 33 and the piston 36 need to move 0.2 mm more relative to the reference A in the positive direction of the X-axis, that is, X = X0 + 2Z0 + 0.2 mm, Y = Y0 + 2Z0 + 0.2 mm, and the sealing ring 39B is elastically deformed by the friction of the piston 36. When the EMB 300 begins to release the brake, the driven mechanism 33 is reversely driven by the actuator 32 and retracts, and the piston 36 retracts due to the rebound force of the elastic deformation of the sealing ring 39B. When X = X0 + 0.2 mm, Y = Y0 + 0.2 mm, and Z = Z0, the volume of the second chamber 38 is determined by H = YX = Y0 - X0, and the pressure in the second chamber 38 is equal to atmospheric pressure. As X continues to decrease from X0 + 0.2 mm to X0, the volume of second chamber 38 increases, creating a certain vacuum. Brake fluid is replenished from the higher-pressure first chamber 37 to the lower-pressure second chamber 38. The friction force exerted by seal 39B prevents piston 36 from further retracting due to atmospheric pressure on the side of first friction plate 34A closest to brake disc 40. Ultimately, when EMB 300 is fully released, the distance X of driven mechanism 33 relative to reference A is X0, the distance Y of piston 36 relative to reference A is Y0 + 0.2 mm, and the gap Z between first and second friction plates 34A and 34B and brake disc 40 is Z0.

[0051] In summary, when the friction pads are worn, the gaps between the first and second friction pads 34A and 34B and the brake disc 40 can, on the one hand, remain the same as when the friction pads are not worn (Z=Z0) when the brake is fully released, thereby ensuring that the drag torque between the brake disc 40 and the friction pads is substantially zero. Furthermore, the thickness of the worn friction pads is compensated for by the brake fluid replenished into the second chamber 38, without requiring additional displacement of the driven mechanism 33 relative to the reference A in the positive direction of the X-axis. This reduces the axial length of the actuator mechanism 32 and the driven mechanism 33 while maintaining braking response speed.

[0052] like Figure 3As shown, the second chamber 38 of the EMB 300 is connected to the hydraulic pressure sensor 20 of the hydraulic system 200 via a liquid outlet line 42. Therefore, the pressure in the second chamber 38 can be detected by the hydraulic pressure sensor 20 and fed back to the electronic control unit 201 of the hydraulic system 200. Based on this pressure feedback signal, the hydraulic system 200 can perform closed-loop control to increase (pressurization), maintain (hold) or reduce (depressurization) the pressure in the first chamber 37 and the second chamber 38.

[0053] The following will refer to Figure 4 To illustrate the boosting condition in the hybrid braking mode according to an embodiment of the present disclosure. Figure 3 In the illustrated pure EMB braking mode, when the pressure in the first and second chambers 37, 38 of a particular EMB needs to be increased, control valve 29 is switched from an open state to a closed state under the control of the electronic control unit 201. When the hydraulic pump 24 and motor 25 begin operating, the hydraulic pump 24 draws brake fluid from the second reservoir 203B and replenishes the brake fluid to the first chamber 37 via the third hydraulic line 23. Because seal 39A allows unidirectional flow of brake fluid from the first chamber 37 to the second chamber 38, the pressure in the second chamber 38 increases until it reaches the target pressure. The clamping force acting on the brake disc 40 includes not only the initial clamping force provided by the EMB 300 but also the additional clamping force gradually increased by the HCA 200, which is achieved through this pressure.

[0054] The following will refer to Figure 5 To illustrate the pressure maintaining condition in the hybrid braking mode according to the embodiment of the present disclosure. Figure 4 Based on the pressure-boosting operation shown, when it is necessary to maintain the pressure in the first and second chambers 37, 38 of a particular EMB, the inlet valve 27 is switched from an open state to a closed state under the control of the electronic control unit 201. Consequently, the brake fluid is isobarically confined in the first and second chambers 37, 38. The clamping force acting on the brake disc 40 includes not only the initial clamping force provided by the EMB 300 but also the additional clamping force provided by the HCA 200, which is maintained constant by the aforementioned pressure.

[0055] The following will refer to Figure 6 To illustrate the decompression condition in the hybrid braking mode according to an embodiment of the present disclosure. Figure 5On the basis of the pressure-maintaining working condition shown, when it is necessary to reduce the pressure in the first chamber 37 and the second chamber 38 of a certain EMB, under the control of the electronic control unit 201, the liquid outlet valve 28 is switched from the closed state to the connected state, and the brake fluid in the first chamber 37 and the second chamber 38 is released into the second fluid storage chamber 203B. In addition to the initial clamping force provided by the EMB 300, the clamping force acting on the brake disc 40 also includes the additional clamping force provided by the HCA 200 which is gradually reduced by the above-mentioned pressure.

[0056] It should be understood that the HCA backup mode of the hybrid braking system 100 is also divided into pressure-increasing, pressure-maintaining and pressure-reducing working conditions. The difference from the hybrid braking mode is that the EMB 300 cannot work due to a fault. The working principles of the pressure-increasing, pressure-maintaining and pressure-reducing working conditions in the HCA backup mode are respectively the same as those in the hybrid braking mode. Figure 4 、 Figure 5 and Figure 6 The HCA 200 shown works in the same way, except that the clamping force acting on the brake disc 40 is only the backup clamping force achieved by the pressure provided by the HCA 200, without the initial clamping force provided by the EMB 300.

[0057] When the hybrid brake system 100 is in HCA degraded mode, the hydraulic system 200 cannot work due to a fault. For the first type of fault, that is, the hydraulic system 200 cannot pressurize the brake fluid, such as the motor 25 or the hydraulic pump 24 fails, the electromechanical brake 300 can be used alone to provide the clamping force. In this case, the working principle of the EMB 300 is the same as that of the Figure 3 The EMB 300 operates in the same principle as shown in the pure EMB braking mode. For the second type of fault, where the hydraulic system 200 is unable to measure the brake fluid pressure, such as when one of the hydraulic sensors 20 fails, the pressure in the second chamber 38 measured by the other hydraulic sensor 20 can be used to simultaneously control the clamping force of the left and right front wheel EMBs 300.

[0058] The following combination Figure 7Let's illustrate the third type of fault, namely, a brake fluid leak in the hydraulic system 200, for example, a leak in the outlet valve 28, which switches from a closed state to an open state. When the hybrid brake system 100 applies the brakes, the EMB 300 begins operating. The brake fluid in the second chamber 38 is expelled by the follower mechanism 33 until the follower mechanism 33 directly contacts the piston 36. This allows the follower mechanism 33 to transmit axial force to the piston 36 without relying on the brake fluid in the second chamber 38, thereby clamping the brake disc 40 via the first and second friction plates 34A and 34B. When the hybrid brake system 100 releases the brakes, the follower mechanism 33 retracts a sufficient distance to ensure that the first and second friction plates 34A and 34B fully release the brake disc 40. The volume of the second chamber 38 increases when the brakes are released relative to the volume when the brakes are applied. This increased volume is replenished by brake fluid flowing from the second reservoir 203B through the outlet valve 28.

[0059] The following reference Figure 8 To explain the fixed caliper. The following will mainly explain Figure 8 and Figure 3 Although Figure 8 The fixed caliper for the left wheel has been described, but the fixed caliper for the right wheel may also have a similar structure.

[0060] like Figure 8 As shown, in this fixed caliper, the first and second parts 31A and 31B forming the caliper body 31 are immovable relative to the brake disc 40. The second chamber 38 is divided into a first sub-chamber 38A and a second sub-chamber 38B, and the second through-hole 38t includes a first branch 38t1 and a second branch 38t2. The piston 36 includes a first piston 36A located in the first part 31A and a second piston 36B located in the second part 31B. The first and second pistons 36A and 36B are sealed to the first and second parts 31A and 31B via sealing rings 39B1 and 39B2, respectively. The first friction plate 34A is connected to the first piston 36A, and the second friction plate 34B is connected to the second piston 36B. The follower mechanism 33 is disposed in the first part 31A.

[0061] When the EMB 300 is braking, the driven mechanism 33 moves in the positive direction of the X axis (eg Figure 8The first piston 36A and the first friction plate 34A move toward the brake disc 40 (left direction as shown) to compress the brake fluid in the first sub-chamber 38A to push the first piston 36A and the first friction plate 34A toward the brake disc 40. Since the first sub-chamber 38A and the second sub-chamber 38B are in fluid communication with each other, a pressure equal to the pressure in the first sub-chamber 38A is applied to the second sub-chamber 38B, thereby pushing the second piston 36B and the second friction plate 34B toward the brake disc 40, and finally clamping the brake disc 40 through the first and second friction plates 34A and 34B. When the EMB 300 releases the brake, the follower mechanism 33 moves in the negative direction of the X axis (as shown). Figure 8 The first and second pistons 36A and 36B move away from the brake disc 40 under the action of the elastic deformation restoring force of the sealing rings 39B1 and 39B2, and finally release the brake disc 40 through the first and second friction plates 34A and 34B.

[0062] The following reference Figure 9 To illustrate the brake fluid circulation mode, although Figure 9 While the brake fluid circulation pattern for a floating caliper is shown, a similar pattern can be employed for a fixed caliper. Reservoir 203 includes a third reservoir chamber 203C in addition to first and second reservoir chambers 203A and 203B. The inlet of the left front wheel's hydraulic pump 24 and the left front wheel's control valve 29 are connected to the first reservoir chamber 203A, the inlet of the right front wheel's hydraulic pump 24 and the right front wheel's control valve 29 are connected to the second reservoir chamber 203B, and the outlet valves 28 for the left and right front wheels are connected to the third reservoir chamber 203C. Furthermore, the first and second reservoir chambers 203A and 203B can be indirectly connected to the inlet port or first through-hole 37t of the wet electromechanical brake 300 for the left and right front wheels, respectively. The third reservoir chamber 203C can be indirectly connected to the outlet port or second through-hole 38t of the aforementioned EMB 300. In the brake fluid circulation mode, the hybrid brake system 100 can realize automatic exhaust and accelerated heat dissipation functions.

[0063] During operation or maintenance of hybrid brake system 100, such as when replacing brake fluid, a certain amount of air may enter the hydraulic lines, thereby affecting braking performance. When this occurs and the vehicle is in a safe state, outlet valve 28 switches from closed to open, and control valve 29 switches from open to closed. Hydraulic pump 24 and motor 25 then begin operating. Brake fluid flows from first and second reservoirs 203A and 203B through hydraulic pump 24, inlet valve 27, first chamber 37, second chamber 38, outlet valve 28, and pipeline 22, ultimately reaching third reservoir 203C. The air in the hydraulic lines also enters third reservoir 203C along with the brake fluid. Because the density of air is lower than that of brake fluid, the air in third fluid reservoir 203C is separated from the brake fluid and discharged into the atmosphere through fluid reservoir sealing cap 203D. The excess air-free brake fluid in third fluid reservoir 203C is then replenished into first and second fluid reservoirs 203A and 203B, thus achieving an automatic air bleed function. The automatic air bleed operation can be performed periodically to ensure that the performance of hybrid brake system 100 remains intact.

[0064] When the temperature of the first and second friction plates 34A and 34B of the electromechanical brake 300 is excessively high, such as during prolonged braking and deceleration while descending a long slope, the friction coefficient of these friction plates drops dramatically at high temperatures, leading to a sharp decline in braking performance. To reduce the temperature of these friction plates, a brake fluid circulation mode can be utilized to accelerate heat dissipation from these friction plates. This is achieved in a manner consistent with the automatic bleed function. Because brake fluid from the reservoir 203 can rapidly flow through the first chamber 37 and the second chamber 38, the caliper body 31 and its internal components, such as the piston 36, can be rapidly cooled, thereby accelerating heat dissipation from the first and second friction plates 34A and 34B.

[0065] Although Figure 9 The automatic exhaust function and accelerated heat dissipation function are illustrated using a floating caliper, but those skilled in the art should understand that a fixed caliper can also use the same method to exhaust air in the hydraulic line and accelerate the heat dissipation of the friction plate.

[0066] Without prejudice to the underlying principles, the details and embodiments may vary, even significantly, from what is described by way of example only, without departing from the scope of protection. The various embodiments described above may be combined to provide additional embodiments. If it is necessary to adopt the concepts of various patents, applications, and publications to provide further embodiments, the various aspects of the embodiments may be modified. These and other changes may be made to the embodiments based on the above detailed description. Generally, in the following claims, the terms used should not be interpreted as limiting the claims to the specific embodiments disclosed in the specification and claims, but rather should be interpreted as including all possible embodiments and the full range of equivalents to which such claims are entitled. Therefore, the claims are not limited by the disclosure.

Claims

1. A hybrid braking system comprising: An electromechanical brake (300) comprising: Clamp body (31); A driven mechanism (33) located in the caliper body and capable of being actuated to move back and forth in a first direction; and a piston (36), wherein a first side of the piston in the first direction faces the driven mechanism, and a second side of the piston in the first direction is located outside the caliper body, A first chamber (37) is formed between the side of the driven mechanism away from the piston and the caliper body, and a second chamber (38) is formed between the driven mechanism and the piston. A hydraulic system (200) comprising: brake fluid supply unit; a first hydraulic line (41) connected to the brake fluid supply unit and connected to the first chamber via a first through hole (37t) passing through the caliper body so that the first chamber is filled with brake fluid; and a second hydraulic line (42) connected to the brake fluid supply unit and connected to the second chamber via a second through hole (38t) passing through the caliper body so that the second chamber is filled with brake fluid; The electromechanical brake is configured such that the brake fluid can flow unidirectionally from the first chamber to the second chamber.

2. The hybrid braking system of claim 1 , wherein the electromechanical brake further comprises: A lip seal (39A) is located between the driven mechanism and the caliper body in a second direction perpendicular to the first direction to separate the first chamber from the second chamber and is configured to allow the brake fluid to flow unidirectionally from the first chamber to the second chamber.

3. The hybrid braking system of claim 1 , wherein the electromechanical brake further comprises: A piston sealing ring (39B) is located between the piston and the caliper body in a second direction perpendicular to the first direction.

4. The hybrid brake system according to claim 1, wherein the brake fluid supply unit comprises a reservoir (203) communicating with air and a brake fluid pressurizing and delivering mechanism (24; 25) connected to the reservoir to draw brake fluid and capable of pressurizing the brake fluid, The hydraulic system further comprises: a liquid inlet valve (27) connected between the first through hole (37t) and the brake fluid pressurizing and delivering mechanism and in a normally open state; a liquid outlet valve (28) connected to the second through hole (38t) and the liquid reservoir (203) and in a normally closed state; as well as The control valve (29) is connected between the first through hole (37t) and the liquid reservoir (203) and is in a normally open state.

5. The hybrid braking system according to claim 4, wherein the hybrid braking system is configured to be operable in any one of the following modes: A pure electromechanical braking mode in which braking force is provided only by the electromechanical brake; A hybrid braking mode in which braking force is provided by both the electromechanical brake and the hydraulic system; a hydraulic system backup mode in which the hydraulic system provides braking force when the electromechanical brake fails; a hydraulic system degradation mode in which the electromechanical brake provides braking force when the hydraulic system fails; or Brake fluid circulation mode.

6. The hybrid braking system according to claim 5 further includes a controller (201), wherein in the pure electric mechanical braking mode, the controller (201) is configured to: make the brake fluid pressurizing and delivering mechanism inoperative, the fluid inlet valve (37) and the control valve (39) in an on state, and the fluid outlet valve (38) in a closed state, so that the hydraulic pressure in the first chamber (37) is maintained at the atmospheric pressure level and the brake fluid in the second chamber (38) transmits the axial force from the driven mechanism (33) to the piston (36) to provide braking force.

7. The hybrid braking system according to claim 5 further includes a controller (201), wherein in the boost condition of the hybrid braking mode or the boost condition of the hydraulic system backup mode, the controller (201) is configured to: enable the brake fluid pressurization delivery mechanism to work, the inlet valve (27) to be in an on state, and the control valve (29) and the outlet valve (28) to be in a closed state, so that the hydraulic pressure in the first chamber (37) can be increased to allow the brake fluid to flow unidirectionally from the first chamber (37) to the second chamber (38) to increase the pressure in the second chamber (38) to increase the braking force.

8. The hybrid braking system according to claim 5 further includes a controller (201), wherein in the pressure-maintaining condition of the hybrid braking mode or the pressure-maintaining condition of the hydraulic system backup mode, the controller (201) is configured to: make the liquid inlet valve (27), the control valve (29) and the liquid outlet valve (28) all in a closed state, so that the hydraulic pressure in the first chamber (37) and the second chamber (38) are equal to maintain the braking force.

9. The hybrid braking system according to claim 5 further includes a controller (201), wherein under the decompression condition of the hybrid braking mode or the decompression condition of the hydraulic system backup mode, the controller (201) is configured to: make the liquid inlet valve (27) and the control valve (29) in a closed state, and the liquid outlet valve (28) in an on state, thereby reducing the hydraulic pressure in the first chamber (37) or the second chamber (38) to reduce the braking force.

10. The hybrid braking system according to claim 5, further comprising a controller (201), wherein in the hydraulic system degradation mode, the controller is configured to: The brake fluid pressurizing and delivering mechanism, the fluid inlet valve (27), the control valve (29) and the fluid outlet valve (28) are made to operate in the same manner as in the pure electric mechanical braking mode, or When the liquid outlet valve (28) cannot be closed, the driven mechanism (33) contacts the piston (36) to provide braking force through the electromechanical brake.

11. The hybrid braking system according to claim 5, wherein the reservoir comprises a first reservoir and a second reservoir, wherein the fluid inlet of the brake fluid pressurizing and delivering mechanism (24) of the left front wheel and the control valve (29) of the left front wheel are connected to the first reservoir, the fluid inlet of the brake fluid pressurizing and delivering mechanism (24) of the right front wheel and the control valve (29) of the right front wheel are connected to the second reservoir, and the fluid outlet valves (28) of the left front wheel and the right front wheel are connected to the third reservoir, and the hybrid braking system further comprises a controller (201), wherein in the brake fluid circulation mode, the controller is configured to: The brake fluid pressurizing and delivering mechanism is operated, the inlet valve (27) and the outlet valve (28) are in an on state, and the control valve (29) is in a closed state, so that the brake fluid can flow from the first or second reservoir via the brake fluid pressurizing and delivering mechanism (24), the inlet valve (27), the first chamber (37), the second chamber (38) and the outlet valve (28) to the third reservoir.

12. The hybrid brake system according to claim 4, wherein the hydraulic system further comprises a hydraulic pressure sensor (20) connected between the outlet valve (28) and the second through hole (38t).

13. The hybrid braking system of claim 1 , wherein the electromechanical brake further comprises: an actuating mechanism (33) passing through the caliper body to extend into the interior of the caliper body, wherein the driven mechanism is driven by the actuating mechanism to move back and forth along the first direction; as well as A first friction plate (34A) and a second friction plate (34B) are located outside the caliper body and on both sides of the brake disc of the vehicle in the first direction, wherein the piston is connected to the first friction plate, and the second friction plate is connected to the caliper body to be opposite to the first friction plate.

14. The hybrid braking system according to claim 13, wherein the electromechanical brake comprises a floating caliper, the floating caliper comprising a first portion (31A) and a second portion (31B) forming the caliper body, the second portion being capable of following the movement of the first portion and thereby moving relative to the brake disc, the first portion moving in a direction opposite to the direction of movement of the piston, The driven mechanism is located in the first portion of the floating caliper, The second friction plate is mounted to the second portion of the floating caliper, and the brake disc of the vehicle is placed between the first portion and the second portion.

15. The hybrid braking system according to claim 13, wherein the electromechanical brake comprises a fixed caliper comprising a first portion (31A) and a second portion (31B) forming the caliper body, the first portion and the second portion being immovable relative to the brake disc, The driven mechanism is located in the first portion of the fixed caliper, The second friction plate is mounted to the second portion of the fixed caliper; the brake disc of the vehicle being positioned between the first portion and the second portion; The second chamber includes a first sub-chamber (38A) located in the first portion and a second sub-chamber (38B) located in the second portion, and the piston is a first piston. The second through hole includes a first branch (38t1) leading to the first sub-chamber and a second branch (38t2) leading to the second sub-chamber, The second sub-chamber includes a second piston, wherein the second friction plate is connected to an outer side of the second piston away from the second sub-chamber, and The second piston is movable synchronously with the first piston in an opposite direction.

16. A vehicle comprising: A plurality of wheels, wherein at least a front left wheel and a front right wheel of the plurality of wheels are provided with the hybrid braking system according to claim 1.

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