Motor-free motorcycle ABS system and control method

Abstract

The invention relates to the field of motorcycle braking systems, and discloses a motor-free motorcycle ABS system and a control method, the motor-free motorcycle ABS system comprises a negative pressure generation unit, a hand brake unit and a return valve; the system further comprises a pressure increasing valve, a pressure reducing valve, an energy accumulator and a braking unit. The hand brake unit is connected with the negative pressure generation unit, the hand brake unit comprises a main cylinder, the main cylinder provides high-pressure brake fluid for an ABS system, the main cylinder is connected with two oil ways, one oil way is communicated with an energy accumulator, the other oil way is communicated with the brake unit through a pressure increasing valve, and the other end of the negative pressure generation unit is connected with a return valve; the reflux valve is connected with the reducing valve; the pressure reducing valve and the pressure increasing valve are connected in parallel and then connected with the brake unit; the energy accumulator is connected between the hand brake unit and the pressure increasing valve through the one-way valve, and the energy accumulator is connected with the return valve and the pressure reducing valve. The brake system has the advantages of low cost, reliability in use and the like.

Description

Technical Field

[0001] The present invention relates to the field of motorcycle braking systems, and mainly relates to a motorless motorcycle ABS system and a control method thereof. Background Art

[0002] The ABS anti-lock braking system is a commonly used active safety control system in automobiles. Its primary function is to regulate the braking force at the wheels during braking to prevent wheel lock. When a wheel locks, the tires slide against the road, resulting in longer stopping distances and even loss of control. The ABS system uses electronic and mechanical control to precisely control the release and withdrawal of brake fluid pressure at extremely high speeds, forcing the wheels into a rolling and sliding state, with a slip ratio of approximately 20%. This ensures maximum braking force and steering ability during braking. This ensures that the vehicle maintains good stability and steering ability even in emergency braking situations.

[0003] Because ABS significantly improves driving safety, it's now being installed not only on cars but also on some high-end motorcycles and electric bicycles to prevent skidding, tailspinning, and even tipping over. Its structure largely mirrors the electronic control architecture of traditional automotive ABS. It primarily consists of a controller, solenoid valves, a pump motor, and a valve body. Based on algorithmic settings, the controller drives the solenoid valves and pump motor to load-regulate wheel pressure under specific conditions, achieving ABS.

[0004] Compared to cars, motorcycles are more affordable and therefore particularly cost-sensitive. While ABS improves performance, it also places high demands on cost control. For example, Chinese patent CN221316488U discloses an ABS disc brake piping system and motorcycles employing it. Among the ABS actuators, the pump motor and plunger pump mechanism are the most expensive, accounting for over 50% of the total HCU cost. Summary of the Invention

[0005] The present invention addresses the shortcomings of the prior art and provides a motorless motorcycle ABS system and a control method.

[0006] A motorless motorcycle ABS system includes a negative pressure generating unit, a handbrake unit, and a return valve; a boost valve, a pressure reducing valve, an accumulator, and a brake unit; the handbrake unit is connected to the negative pressure generating unit, and the handbrake unit includes a master cylinder, which provides high-pressure brake fluid for the ABS system. The master cylinder is connected to two oil circuits, one of which is connected to the accumulator and the other is connected to the brake unit through the boost valve. The other end of the negative pressure generating unit is connected to the return valve; the return valve is connected to the pressure reducing valve; the pressure reducing valve and the boost valve are connected in parallel to the brake unit; the accumulator is connected between the handbrake unit and the pressure increasing valve through a one-way valve, and the accumulator is connected to the return valve and the pressure reducing valve.

[0007] Preferably, the boost valve is a normally open solenoid valve, and the pressure reducing valve is a normally closed solenoid valve; in the driving state, the brake fluid of the handbrake unit flows into the brake unit through the boost valve.

[0008] Preferably, the negative pressure generating unit includes a cylinder body, a spring and a stretching unit of the stretching spring. A piston is provided in the cylinder body. The two ends of the stretching spring are respectively connected to the stretching unit and the piston. The stretching unit is linked to the handbrake unit. The handbrake unit is connected to the stretching spring through the stretching unit. The cylinder body forms a negative pressure chamber on the other side of the piston. When the spring is stretched, negative pressure is generated in the negative pressure chamber.

[0009] Preferably, the reflux valve is a normally open solenoid valve, and the reflux valve and the accumulator are connected to the negative pressure chamber. When the reflux valve is in the open state, the negative pressure chamber generates negative pressure and the accumulator also generates negative pressure.

[0010] Preferably, the one-way valve is opened so that the liquid flows from the accumulator to the liquid inlet end of the boosting valve.

[0011] A motorless motorcycle ABS control method includes a negative pressure generating unit, a boost valve, a pressure reducing valve, a return valve, a handbrake unit, and an accumulator; the boost valve is a normally open solenoid valve, the pressure reducing valve is a normally closed solenoid valve, and the return valve is a normally open solenoid valve; the negative pressure generating unit includes a negative pressure chamber, which is connected to the return valve; the negative pressure generating unit includes a tension unit, a cylinder, and a tension spring; a piston driven by the tension spring is disposed in the cylinder; and the tension spring is connected to the handbrake unit via the tension unit. The control method includes one or more of the following: a pressure increase phase, a pressure maintenance phase, a conventional ABS pressure relief phase, a deep ABS pressure relief phase, and a brake release phase; During the boost phase, the vehicle switches from a normal driving state to a braking state, which includes the following steps: S1: The vehicle is in normal driving, the boost solenoid valve is open, the return solenoid valve is open, and the decompression solenoid valve is closed; S2: Operate the handbrake unit, the pressure of the brake master cylinder in the handbrake unit increases, and the brake fluid enters the brake unit through the booster solenoid valve to apply the brake; S3. When the handbrake unit is tightened, the stretching unit drives the stretching spring, which drives the piston to move, generating negative pressure in the negative pressure chamber. The accumulator is connected to the negative pressure chamber through the return valve, and negative pressure is generated in the accumulator through the internal spring. The vehicle transitions from the boost phase to the pressure-maintaining phase, including the following steps: S4. When the vehicle tends to lock, the boost valve closes, the brake fluid in the handbrake unit no longer enters the brake unit, the brake pressure of the brake unit is constant, and the vehicle is in the pressure holding stage; after entering the pressure holding stage, the return valve closes, the negative pressure chamber and the accumulator are isolated, and both the negative pressure chamber and the accumulator are in a negative pressure state.

[0012] Preferably, when the vehicle is completely locked during braking, the vehicle slips and enters the conventional ABS pressure relief stage, the control method includes: S5, pressure relief stage: the pressure reducing valve opens, while the return valve and the pressure boosting valve are closed. The brake fluid in the brake unit flows into the accumulator under the negative pressure of the accumulator, the pressure of the brake unit drops, and the wheels resume rotation. S6. After the pressure relief is completed, the controller controls the boost valve to open and enter the boost state for braking again; at the same time, the system prepares for the next locking pressure relief.

[0013] Preferably, when the negative pressure in the accumulator is 0 and the pressure of the accumulator and the brake unit is close to being unable to be relieved, the vehicle enters the deep ABS pressure relief stage. After the conventional ABS pressure relief stage fails to achieve the purpose of pressure relief, the deep ABS pressure relief is performed through the following control method: S7. When the controller detects that the pressure relief fails, the controller opens the reflux valve. Under the action of the negative pressure in the negative pressure chamber, the brake fluid in the brake unit flows through the reflux valve into the negative pressure chamber, thereby further relieving the pressure of the brake unit. S8: After the pressure of the brake unit is reduced and the wheel speed is restored, the pressure reducing valve is closed, the pressure boosting valve is opened, and the return valve is in the open state. The brake unit is pressurized for a new round of braking and waits for the next ABS adjustment.

[0014] Preferably, the control method of the braking exit phase includes: S10. When it is detected that the driver releases the brake handle and the brake switch is reset, the boost valve and the reflux valve are opened, the pressure reducing valve is closed, and the oil in the negative pressure chamber returns to the master cylinder of the handbrake unit through the reflux valve and the one-way valve. The oil in the accumulator returns to the master cylinder of the handbrake unit through the one-way valve, and the oil in the brake unit returns to the master cylinder of the manual unit through the boost valve.

[0015] Compared with existing technologies, this solution offers the following advantages: It proposes an ABS architecture without a motor or plunger pump, and employs two-stage ABS control, achieving excellent control while reducing costs. Furthermore, a negative pressure mechanism allows for rapid pressure relief in ABS conditions, ensuring excellent braking even in low-load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a functional diagram of the conventional brake boost stage.

[0017] Figure 2 It is a functional diagram of the pressure holding stage.

[0018] Figure 3 It is a functional diagram of the ordinary ABS stage.

[0019] Figure 4 It is a functional diagram of the deep pressure relief ABS stage.

[0020] Figure 5 It is a functional diagram of brake release after deep pressure relief.

[0021] The reference numerals in the figure refer to: 1—negative pressure generating unit, 2—handbrake unit, 3—backflow valve, 4—boost valve, 5—pressure reducing valve, 6—accumulator, 7—brake unit, 8—check valve, 9—piston, 10—negative pressure chamber, 11—cylinder, 12—spring, 13—tension unit. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0023] Example 1 A motorless motorcycle ABS system includes a negative pressure generating unit 1, a handbrake unit 2, and a return valve 3; a boost valve 4, a pressure reducing valve 5, an accumulator 6, and a brake unit 7; the handbrake unit 2 is connected to the negative pressure generating unit 1, and the handbrake unit 2 includes a master cylinder, which provides high-pressure brake fluid for the ABS system. The master cylinder is connected to two oil circuits, one of which is connected to the accumulator 6 and the other is connected to the brake unit 7 through the boost valve 4. The other end of the negative pressure generating unit 1 is connected to the return valve 3; the return valve 3 is connected to the pressure reducing valve 5; the pressure reducing valve 5 and the boost valve 4 are connected in parallel to the brake unit 7; the accumulator 6 is connected between the handbrake unit 2 and the pressure increasing valve 4 through a one-way valve 8, and the accumulator 6 is connected to the return valve 3 and the pressure reducing valve 5.

[0024] Specifically, in this solution, the plunger pump and motor structure are omitted. In this solution, the handbrake unit 2 is connected to the brake master cylinder, which contains high-pressure brake fluid. The master cylinder has two oil circuits, one of which is connected to the accumulator 6. A one-way valve 8 is installed between the accumulator 6 and the master cylinder. The one-way valve 8 only allows the accumulator 6 to pass to the master cylinder and not the other way around. A booster valve 4 is installed between the master cylinder and the brake unit 7. The accumulator 6 and the brake unit 7 are connected, and a pressure reducing valve 5 is installed on the connection path. The pressure reducing valve 5 is connected to the oil circuit between the pressure increasing valve 4 and the brake unit 7.

[0025] In this embodiment, the pressure-boosting valve 4 is a normally open solenoid valve, and the pressure-reducing valve 5 is a normally closed solenoid valve; in the driving state, the brake fluid of the handbrake unit 2 flows into the brake unit 7 through the pressure-boosting valve 4 .

[0026] The negative pressure generating unit 1 includes a cylinder body 11, a spring 12 and a stretching unit 13 for stretching the spring 12. A piston 9 is provided in the cylinder body 11. The two ends of the stretching spring 12 are respectively connected to the stretching unit 13 and the piston 9. The stretching unit 13 is linked to the handbrake unit 2. The handbrake unit 2 is connected to the stretching spring 12 through the stretching unit 13. The cylinder body 11 forms a negative pressure chamber 10 on the other side of the piston 9. When the spring 12 is stretched, negative pressure is generated in the negative pressure chamber 10.

[0027] Moreover, the return valve 3 is a normally open electromagnetic valve, and the return valve 3 and the accumulator 6 are connected, and the return valve 3 and the negative pressure chamber 10 are connected. When the return valve 3 is in the open state, the negative pressure chamber 10 generates negative pressure and the accumulator 6 also generates negative pressure.

[0028] This solution obviously also includes a controller, which is connected to the boost valve 4, the pressure reducing valve 5, and the return valve 3, and is electrically controlled by controlling the on and off states of each solenoid valve. As previously mentioned, the one-way valve 8 is connected to the inlet end of the boost valve 4, where the liquid flows from the accumulator 6.

[0029] Example 2 This embodiment, Example 1, describes a specific control method of an ABS control system, in which each component is briefly described again.

[0030] A motorless motorcycle ABS control method includes a negative pressure generating unit 1, a boost valve 4, a pressure reducing valve 5, a return valve 3, a handbrake unit 2, and an accumulator 6. The boost valve 4 is a normally open solenoid valve, the pressure reducing valve 5 is a normally closed solenoid valve, and the return valve 3 is a normally open solenoid valve. The negative pressure generating unit 1 includes a negative pressure chamber 10, which is connected to the return valve 3. The negative pressure generating unit 1 includes a stretching unit 13, a cylinder 11, and a stretching spring 12. The cylinder 11 is provided with a piston 9 that can be driven by the stretching spring 12. The stretching spring 12 is connected to the handbrake unit 2 through the stretching unit 13. The control method includes one or more of the following stages: a pressure boosting stage, a pressure maintaining stage, a conventional ABS pressure relief stage, a deep ABS pressure relief stage, and a brake exit stage; specifically, in this embodiment, the control method includes all of the above stages.

[0031] During the boosting phase, the vehicle switches from a normal driving state to a braking state, including the following steps: S1: The vehicle is in normal driving, the boost solenoid valve is open, the return solenoid valve is open, and the decompression solenoid valve is closed; S2: Operate the handbrake unit 2. The pressure in the master cylinder of the handbrake unit 2 increases, and the brake fluid enters the brake unit 7 through the booster solenoid valve to apply the brake. The high-pressure brake fluid in the master cylinder enters the brake unit 7 through the booster valve 4. Due to the presence of the one-way valve and the closed pressure reducing valve 5, the brake fluid does not flow into the accumulator 6. S3. During the tightening process of the handbrake unit 2, the tension spring 12 is driven by pulling the tension unit 13, and the tension spring 12 drives the piston 9 to move, and the negative pressure chamber 10 generates negative pressure. The accumulator 6 is connected to the negative pressure chamber 10 through the return valve 3, and negative pressure is generated in the accumulator 6 through the internal spring 12; the generated negative pressure can be used for subsequent ABS adjustment.

[0032] S2 and S3 in this section are not step sequences, but only indicate the existence of the process. The same applies to the other marked steps.

[0033] The vehicle transitions from the boost phase to the pressure-maintaining phase. The vehicle does not lock during this process, and the steps are as follows: S4. When the vehicle tends to lock, the boost valve 4 closes, and the brake fluid in the parking brake unit 2 no longer enters the brake unit 7. The brake pressure of the brake unit 7 remains constant, and the vehicle enters the pressure holding stage. After entering the pressure holding stage, the return valve 3 closes, isolating the negative pressure chamber 10 from the accumulator 6. Both the negative pressure chamber 10 and the accumulator 6 are in a negative pressure state. The vehicle is in a normal braking state.

[0034] As described above, when the vehicle is emergency braked, that is, when the wheels are completely locked during braking and the vehicle slips, in order to reduce the danger, the conventional ABS pressure relief stage is entered at this time, and the control method includes: S5, pressure relief stage: the pressure reducing valve 5 opens, while the return valve 3 and the pressure boosting valve 4 are closed. The brake fluid in the brake unit 7 flows into the accumulator 6 under the negative pressure of the accumulator 6, and the pressure of the brake unit 7 drops, and the wheel resumes its ability to rotate. This achieves a one-time pressure relief. The return valve 3 remains closed, and a small amount of fluid returns to the master cylinder through the one-way valve 8. This part has little effect on the driver's feel, and there is no soft feel like traditional ABS, making it easier to control. S6. After the pressure relief is completed, the controller controls the boost valve 4 to open and enter the boost state, and the high-pressure brake fluid enters the brake unit 7 for braking again; at the same time, the system prepares for the next locking pressure relief; if the locking condition persists, repeat step S5 for another pressure relief.

[0035] Because in low-adhesion road conditions such as rain, snow, and slippery roads, one braking operation requires multiple ABS adjustment cycles. This may cause the negative pressure in accumulator 6 to be exhausted, and the pressure of accumulator 6 to approach the wheel cylinder pressure. At this time, accumulator 6 can no longer achieve the purpose of pressure relief, and the wheel cylinder continues to lock, requiring the deep ABS stage to be entered.

[0036] When conventional ABS pressure relief fails to achieve the desired pressure relief, deep ABS pressure relief is performed using the following control methods: S7. When the controller detects that the pressure relief fails, the controller opens the reflux valve 3. Under the action of the negative pressure in the negative pressure chamber 10, the brake fluid in the brake unit 7 flows through the reflux valve 3 into the negative pressure chamber 10, thereby further relieving the pressure in the brake unit 7. S8. After the pressure of the brake unit 7 is reduced and the wheel speed is restored, the pressure reducing valve 5 is closed, the pressure increasing valve 4 is opened, and the return valve 3 is in the open state. The brake unit 7 is pressurized for a new round of braking and waits for the next ABS adjustment.

[0037] During the deep pressure relief stage, the oil will enter the negative pressure chamber 10, thereby impacting the handbrake. The tension spring 12 can play a shock-absorbing role in this process, minimizing the fluctuation of the hand feel.

[0038] The control method of the final braking exit stage includes: S10. When it is detected that the driver releases the brake handle and the brake switch is reset, the boost valve 4 and the return valve 3 are opened, the pressure reducing valve 5 is closed, and the oil in the negative pressure chamber 10 returns to the master cylinder of the handbrake unit 2 through the return valve 3 and the one-way valve 8. The oil in the accumulator 6 returns to the master cylinder of the handbrake unit 2 through the one-way valve 8, and the oil in the brake unit 7 returns to the master cylinder of the manual unit through the boost valve 4.

[0039] Compared with existing technologies, this solution offers the following advantages: It proposes an ABS architecture without a motor or plunger pump, and employs two-stage ABS control, achieving excellent control while reducing costs. Furthermore, a negative pressure mechanism allows for rapid pressure relief in ABS conditions, ensuring excellent braking even in low-load conditions.

[0040] Example 3 In this embodiment, the brake unit 7 includes a wheel cylinder, which is used to be connected to the brake fluid circuit of the system.

Claims

1. A motorless motorcycle ABS system, characterized by: The invention comprises a negative pressure generating unit (1), a hand brake unit (2), and a return valve (3); a pressure boosting valve (4), a pressure reducing valve (5), an accumulator (6), and a brake unit (7); the hand brake unit (2) is connected to the negative pressure generating unit (1); the hand brake unit (2) comprises a master cylinder, which provides high-pressure brake fluid for the ABS system; the master cylinder is connected to two oil circuits, one of which is connected to the accumulator (6), and the other is connected to the brake unit (7) through the pressure boosting valve (4); the other end of the negative pressure generating unit (1) is connected to the return valve (3); the return valve (3) is connected to the pressure reducing valve (5); the pressure reducing valve (5) and the pressure boosting valve (4) are connected in parallel to the brake unit (7); the accumulator (6) is connected between the hand brake unit (2) and the pressure boosting valve (4) through a one-way valve (8); the accumulator (6) is connected to the return valve (3) and the pressure reducing valve (5).

2. The motorless motorcycle ABS system according to claim 1, characterized in that: The boost valve (4) is a normally open electromagnetic valve, and the pressure reducing valve (5) is a normally closed electromagnetic valve; in the driving state, the brake fluid of the handbrake unit (2) flows into the brake unit (7) through the boost valve (4).

3. The motorless motorcycle ABS system according to claim 2, characterized in that: The negative pressure generating unit (1) includes a cylinder (11), a spring (12), and a stretching unit (13) of the stretching spring (12). A piston (9) is provided in the cylinder (11). The two ends of the stretching spring (12) are respectively connected to the stretching unit (13) and the piston (9). The stretching unit (13) is linked to the handbrake unit (2). The handbrake unit (2) is connected to the stretching spring (12) through the stretching unit (13). The cylinder (11) forms a negative pressure chamber (10) on the other side of the piston (9). When the spring (12) is stretched, negative pressure is generated in the negative pressure chamber (10).

4. The motorless motorcycle ABS system according to claim 3, characterized in that: The return valve (3) is a normally open electromagnetic valve. The return valve (3) and the accumulator (6) are connected, and the return valve (3) and the negative pressure chamber (10) are connected. When the return valve (3) is in the open state, the negative pressure chamber (10) generates negative pressure and the accumulator (6) also generates negative pressure.

5. The motorless motorcycle ABS system according to claim 1, characterized in that: The one-way valve (8) leads to the liquid inlet end of the accumulator (6) flowing into the boost valve (4).

6. A motorless motorcycle ABS control method, characterized by: The invention comprises a negative pressure generating unit (1), a pressure-increasing valve (4), a pressure-reducing valve (5), a return valve (3), a handbrake unit (2) and an accumulator (6); the pressure-increasing valve (4) is a normally open electromagnetic valve, the pressure-reducing valve (5) is a normally closed electromagnetic valve and the return valve (3) is a normally open electromagnetic valve; the negative pressure generating unit (1) comprises a negative pressure chamber (10), the negative pressure chamber (10) is connected to the return valve (3); the negative pressure generating unit (1) comprises a stretching unit (13), a cylinder (11) and a stretching spring (12); a piston (9) which can be driven by the stretching spring (12) is provided in the cylinder (11); the stretching spring (12) is connected to the handbrake unit (2) through the stretching unit (13); The control method includes one or more of the following: a pressure increase phase, a pressure maintenance phase, a conventional ABS pressure relief phase, a deep ABS pressure relief phase, and a brake release phase; During the boost phase, the vehicle switches from a normal driving state to a braking state, which includes the following steps: S1: The vehicle is in normal driving, the boost solenoid valve is open, the return solenoid valve is open, and the decompression solenoid valve is closed; S2, operating the handbrake unit (2), the pressure of the brake master cylinder in the handbrake unit (2) increases, and the brake fluid enters the brake unit (7) through the booster solenoid valve to brake; S3, during the tightening process of the handbrake unit (2), the stretching unit (13) is pulled to drive the stretching spring (12), the stretching spring (12) drives the piston (9) to move, the negative pressure chamber (10) generates negative pressure, the accumulator (6) is connected to the negative pressure chamber (10) through the return valve (3), and the internal spring (12) generates negative pressure in the accumulator (6); The vehicle transitions from the boost phase to the pressure-maintaining phase, including the following steps: S4. When the vehicle tends to lock, the boost valve (4) is closed, the brake fluid of the handbrake unit (2) no longer enters the brake unit (7), the brake pressure of the brake unit (7) is constant, and the vehicle is in the pressure holding stage; after entering the pressure holding stage, the return valve (3) is closed, the negative pressure chamber (10) and the accumulator (6) are isolated, and both the negative pressure chamber (10) and the accumulator (6) are in a negative pressure state.

7. The motorless motorcycle ABS control method according to claim 6, characterized in that: When the vehicle is completely locked during braking and begins to slip, it enters the conventional ABS pressure relief phase. The control methods include: S5, pressure relief stage, the pressure reducing valve (5) is opened, at this time the return valve (3) and the pressure boosting valve (4) are in the closed state, the brake fluid of the brake unit (7) flows into the accumulator (6) under the negative pressure of the accumulator (6), the pressure of the brake unit (7) drops, and the wheel resumes its ability to rotate; S6. After the pressure relief is completed, the controller controls the boost valve (4) to open and enter the boost state for braking again; at the same time, the system prepares for the next locking pressure relief.

8. The motorless motorcycle ABS control method according to claim 7, characterized in that: When the negative pressure in the accumulator (6) is 0, and the pressures in the accumulator (6) and the brake unit (7) are close to being unable to be released, the vehicle enters the deep ABS pressure relief stage. After the conventional ABS pressure relief stage fails to achieve the purpose of pressure relief, the deep ABS pressure relief is performed through the following control method: S7. When the controller detects that the pressure relief fails, the controller opens the return valve (3), and the brake fluid of the brake unit (7) enters the negative pressure chamber (10) through the return valve (3) under the action of the negative pressure of the negative pressure chamber (10), thereby further relieving the pressure of the brake unit (7); S8, after the pressure of the brake unit (7) is reduced and the wheel speed is restored, the pressure reducing valve (5) is closed, the pressure increasing valve (4) is opened, the return valve (3) is in the open state, and the brake unit (7) is pressurized for a new round of braking and waits for the next ABS adjustment.

9. The motorless motorcycle ABS control method according to claim 6, characterized in that: The control methods for the brake exit phase include: S10. When it is detected that the driver releases the brake handle and the brake switch is reset, the boost valve (4) and the return valve (3) are opened, the pressure reducing valve (5) is closed, and the oil in the negative pressure chamber (10) returns to the master cylinder of the handbrake unit (2) through the return valve (3) and the one-way valve (8), the oil in the accumulator (6) returns to the master cylinder of the handbrake unit (2) through the one-way valve (8), and the oil in the brake unit (7) returns to the master cylinder of the manual unit through the boost valve (4).

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