Electronic parking brake system and working method thereof

Abstract

The invention discloses an electronic parking braking system which comprises an oil storage mechanism, a parking executing mechanism and an oil pumping mechanism, wherein the oil storage mechanism is used for storing hydraulic oil for parking; the parking executing mechanism is used for performing parking braking operation by discharging the hydraulic oil or performing parking releasing operation by injecting the hydraulic oil; the oil pumping mechanism is used for pumping out hydraulic oil of the oil storage mechanism; the energy storage mechanism is used for receiving hydraulic oil pumped out by the oil pumping mechanism and storing energy; the oil injection control mechanism is used for controlling whether the hydraulic oil of the energy storage mechanism enters the parking executing mechanism or not; the oil return control mechanism is used for controlling whether the hydraulic oil of the parking executing mechanism flows back to the oil storage mechanism or not; the oil injection control mechanism can enable hydraulic oil to enter the parking executing mechanism to perform parking releasing operation in a power-on state, and the oil return control mechanism can enable the hydraulic oil to be discharged out of the parking executing mechanism to perform parking braking operation in a power-off state.

Description

Technical Field

[0001] The present invention relates to the technical field of parking brake systems for large-tonnage off-road vehicles, and in particular to an electronic parking brake system and a working method thereof. Background Art

[0002] For motor vehicles, the parking brake system is crucial for driving safety, ensuring the vehicle does not roll after being parked. Currently, traditional parking brake systems for motor vehicles primarily consist of two types: a mechanical parking brake, which locks the drive shaft or rear wheels by operating the parking brake handle and connecting the brake cable via a cable; and a pneumatic manual parking brake, which utilizes a manual valve to control the flow of air, pushing the brake through the brake chamber to perform the parking brake operation.

[0003] However, with the rapid development of intelligent vehicle technology, traditional mechanical parking solutions, due to their reliance on manual operation and the resulting shortcomings of low control accuracy and slow response speed, are no longer able to meet the demand for automated and precise vehicle braking systems in intelligent driving scenarios. Against this backdrop, electronic control and intelligentization have become inevitable trends in parking brake system upgrades. This has led to the emergence of electronic parking brake systems, which utilize an electronic controller to control the opening and closing of a solenoid valve to achieve parking and release functions. Compared to traditional mechanical solutions, these systems offer significant advantages in terms of high control accuracy and fast response speed. They can also integrate temporary parking during driving with long-term parking after parking, optimizing the user experience.

[0004] However, for large-tonnage off-road vehicles, the above-mentioned conventional electronic parking solutions still have limitations. Large-tonnage off-road vehicles operate in complex environments, and they place extremely high demands on the reliability, response speed, and energy consumption control of the braking system. If a motor-driven electronic control solution is used, frequent braking and long-term parking conditions will consume a lot of power, making it difficult to meet the vehicle's endurance requirements. Traditional mechanical parking or pneumatic parking solutions are not only low in intelligence, but also have complex structures, delayed responses, and insufficient reliability. They are unable to meet the emergency braking and stable parking needs of large-tonnage off-road vehicles under complex road conditions. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned background technology and to provide an electronic parking brake system and its working method which has high reliability, fast response speed, low energy consumption, low cost, wide application range and can meet the parking and releasing needs of large-tonnage off-road vehicles.

[0006] To achieve this object, the electronic parking brake system designed in the present invention includes an oil storage mechanism for storing hydraulic oil for parking, a parking actuator for performing a parking brake operation by discharging hydraulic oil or a parking release operation by injecting hydraulic oil, and an oil pumping mechanism for pumping out the hydraulic oil of the oil storage mechanism; it also includes an energy storage mechanism for receiving the hydraulic oil pumped out by the oil pumping mechanism and storing energy, an oil injection control mechanism for controlling whether the hydraulic oil of the energy storage mechanism enters the parking actuator, and an oil return control mechanism for controlling whether the hydraulic oil of the parking actuator flows back to the oil storage mechanism; the oil injection control mechanism can allow the hydraulic oil to enter the parking actuator for the parking release operation when the power is on, and the oil return control mechanism can allow the hydraulic oil to be discharged from the parking actuator for the parking brake operation when the power is off.

[0007] Furthermore, the parking actuator includes a brake, a cable connected to the brake, and a parking actuator connected to the cable for receiving or discharging hydraulic oil. The parking actuator includes an actuator housing and a cable connection structure arranged inside the actuator. The cable connection structure can loosen the cable to unlock the brake when the parking actuator is injected with hydraulic oil, or tighten the cable to apply the brake when the parking actuator discharges the hydraulic oil.

[0008] Furthermore, the cable connection structure is an elastic structure, which includes a cable connector fixed to the cable and an elastic member with both ends respectively fixed to the inside of the actuator housing and the cable connector. The cable connector can tighten the cable under the action of the elastic member or when the parking actuator is injected with hydraulic oil, the hydraulic oil pushes the cable connector to compress the elastic member so that the cable connector relaxes the cable.

[0009] Furthermore, the oil injection control mechanism includes a normally closed solenoid valve connected between the energy storage mechanism and the parking actuator.

[0010] Furthermore, the oil injection control mechanism also includes an oil injection safety device for allowing hydraulic oil to enter the parking actuator when the normally closed solenoid valve fails, which includes a manual stop valve connected between the energy storage mechanism and the parking actuator and arranged in parallel with the normally closed solenoid valve.

[0011] Furthermore, the oil return control mechanism includes a normally open solenoid valve connected between the parking actuator and the oil storage mechanism.

[0012] Furthermore, the oil return control mechanism also includes an oil return safety device for preventing hydraulic oil from discharging from the parking actuator when the normally open solenoid valve fails, which includes a flow regulating valve connected between the normally open solenoid valve and the oil storage mechanism and arranged in series with the normally open solenoid valve.

[0013] Furthermore, a working method based on an electronic parking brake system is designed, which includes a parking brake control method and a parking contact control method;

[0014] The parking brake control method includes: powering off the oil injection control mechanism and the oil return control mechanism to prevent hydraulic oil from entering the parking actuator and returning the hydraulic oil of the parking actuator to the oil storage mechanism.

[0015] The parking release control method includes: energizing an oil injection control mechanism and an oil return control mechanism to allow hydraulic oil to flow into the parking actuator and prevent the hydraulic oil in the parking actuator from flowing back to the oil storage mechanism.

[0016] Furthermore, the parking brake control method includes a long-term parking brake control method for long-term parking of a vehicle and a temporary parking brake control method for temporary parking of a vehicle;

[0017] The long-term parking brake control method includes: after the vehicle stops, power is turned off, so that the oil injection control mechanism forms an open circuit and the hydraulic oil cannot enter the parking actuator, and the oil return control mechanism forms a passage and the hydraulic oil flows back from the parking actuator to the oil storage mechanism;

[0018] The temporary parking brake control method includes: keeping the power on after the vehicle stops, and performing power-off operations on the oil injection control mechanism and the oil return control mechanism, so that the oil injection control mechanism forms an open circuit and the hydraulic oil cannot enter the parking actuator, and the oil return control mechanism forms a passage and the hydraulic oil flows back from the parking actuator to the oil storage mechanism.

[0019] Furthermore, the working method of the electronic parking brake system also includes a working method of an energy storage mechanism, which includes: monitoring the hydraulic oil pressure inside the energy storage mechanism; if the hydraulic oil pressure inside the energy storage mechanism is lower than a set value, pumping the hydraulic oil into the energy storage mechanism through the oil pumping mechanism until the hydraulic oil pressure inside the energy storage mechanism reaches the set value; the oil pumping mechanism stops pumping oil and performs a pressure maintaining operation on the energy storage mechanism.

[0020] The beneficial effects of the present invention are:

[0021] 1. The oil injection control mechanism adopts a dual design of a normally closed solenoid valve and a manual shut-off valve in parallel. Under normal conditions, the hydraulic oil is controlled by the normally closed solenoid valve. If the normally closed solenoid valve fails, the manual shut-off valve can be used to force oil injection to ensure the reliability of the parking release function. The oil return control mechanism adopts a structure in which a normally open solenoid valve and a flow control valve are connected in series. When the normally open solenoid valve fails, the flow control valve can prevent abnormal discharge of hydraulic oil, avoid accidental release of the parking brake, and improve system safety. The elastic cable connection structure (such as a spring) inside the parking actuator can still maintain the braking state through mechanical force when the hydraulic system fails, avoiding failure of the parking function due to power outage or hydraulic leakage, forming a "hydraulic + mechanical" dual protection.

[0022] 2. The accumulator pre-stores high-pressure hydraulic oil. When the parking brake needs to be released, there's no need to temporarily activate the pump mechanism; instead, the oil injection control mechanism rapidly releases hydraulic energy, achieving millisecond-level response and significantly improving operational efficiency. Temporary parking requires the system to remain powered on, and braking is triggered by powering off. For extended parking, braking is automatically triggered after power is removed, preventing safety hazards caused by driver forgetfulness. The accumulator monitors hydraulic oil pressure in real time and automatically replenishes pressure when it falls below a threshold, ensuring the system is always ready and preventing response delays due to insufficient pressure. When the parking brake is engaged (power off), the oil return control mechanism activates, allowing hydraulic oil to flow back to the reservoir. The parking actuator utilizes a resilient structure to achieve braking, eliminating the need for continuous power consumption and significantly reducing energy consumption compared to traditional electric parking systems. A hydraulic-mechanical linkage design eliminates complex transmission components such as motors and gearboxes, reducing mechanical wear and maintenance costs. Core components (such as the solenoid valve and accumulator) are standardized hydraulic components, resulting in low procurement and replacement costs. The system also boasts high system integration, minimal installation space requirements, and strong adaptability.

[0023] 3. The hydraulic system's output force is controllable and stable. By adjusting the energy storage pressure and actuator structure, it can be easily adapted to the parking requirements of vehicles of varying tonnages (especially large off-road vehicles), overcoming the issue of insufficient braking force under heavy loads in traditional mechanical parking systems. The hydraulic medium can withstand harsh operating conditions such as high and low temperatures, and vibration. Combined with a sealed design, it is suitable for complex off-road and heavy-load scenarios, avoiding the reliability degradation of traditional electronic parking systems in extreme environments.

[0024] 4. The system defaults to power-off braking (oil return control mechanism engaged), complying with the "fail-safe" principle. Even in the event of a complete electronic control system failure, the mechanical structure maintains the braking state, minimizing the risk of an accident. The energy storage mechanism's automatic pressure replenishment logic reduces manual intervention and automatically switches to parking mode based on vehicle start / stop signals (such as ignition on / off), enhancing operational convenience and intelligence.

[0025] In summary, the present invention breaks through the limitations of traditional parking systems in terms of reliability, energy consumption and scope of application through hydraulic-mechanical coordinated control, redundant insurance design and intelligent pressure management. It is particularly suitable for high-load scenarios such as large-tonnage off-road vehicles, and provides an efficient, economical and stable solution for vehicle parking safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the electronic parking brake system designed for the present invention;

[0027] Among them, 1—oil storage mechanism, 2—parking actuator, 3—oil pumping mechanism, 4—energy storage mechanism, 5—oil injection control mechanism (5.1—normally closed solenoid valve, 5.2—manual stop valve), 6—oil return control mechanism (6.1—normally open solenoid valve, 6.2—flow regulating valve), 7—brake, 8—cable, 9—parking actuator (9.1—actuator housing, 9.2—cable connector, 9.3—elastic member), 10—pressure sensor, 11—check valve. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] like Figure 1 As shown, in certain embodiments, the electronic parking brake system designed by the present invention includes an oil storage mechanism 1 for storing hydraulic oil for parking, a parking actuator 2 for performing a parking brake operation by discharging hydraulic oil or performing a parking release operation by injecting hydraulic oil, an oil pumping mechanism 3 for pumping out the hydraulic oil of the oil storage mechanism 1, an energy storage mechanism 4 for receiving the hydraulic oil pumped out by the oil pumping mechanism 3 and storing energy, an oil injection control mechanism 5 for controlling whether the hydraulic oil of the energy storage mechanism 4 enters the parking actuator 2, and an oil return control mechanism 6 for controlling whether the hydraulic oil of the parking actuator 2 flows back to the oil storage mechanism 1.

[0030] Example 1

[0031] A specific embodiment of an oil storage mechanism 1 is provided:

[0032] The oil storage mechanism 1 is an oil pot or an oil tank.

[0033] Example 2

[0034] A specific embodiment of a parking actuator 2 is provided:

[0035] The parking actuator 2 includes a brake 7, a cable 8 connected to the brake 7, and a parking actuator 9 connected to the cable 8 for receiving or draining hydraulic oil. The parking actuator 9 includes an actuator housing 9.1 and a cable connection structure disposed therein. The cable connection structure can release the brake 7 by loosening the cable 8 when the parking actuator 9 is injected with hydraulic oil, or tighten the cable 8 to apply the brake 7 when the parking actuator 9 is draining the hydraulic oil. Specifically, the cable connection structure includes a cable connector 9.2 fixed to the cable 8 and a spring (i.e., an elastic member 9.3) with its ends respectively fixed to the interior of the actuator housing 9.1 and to the cable connector 9.2. When the parking actuator 9 is not injected with hydraulic oil, the cable connector 9.2, under the action of the elastic member 9.3, tightens the cable 8, thereby applying the parking brake 7. When the parking actuator 9 is injected with hydraulic oil, the hydraulic oil pushes the cable connector 9.2 to compress the spring, and the cable connector 9.2 releases the cable 8, thereby achieving the brake unlocking operation of the brake 7.

[0036] Example 3

[0037] A specific embodiment of an oil pump mechanism 3 is provided:

[0038] The oil pumping mechanism 3 is an assembly structure of a plunger pump and a motor, wherein the oil inlet of the plunger pump is connected to the oil storage mechanism 1 .

[0039] Example 4

[0040] A specific embodiment of an energy storage mechanism 4 is provided:

[0041] The energy storage mechanism 4 is an accumulator, and a one-way valve 11 is connected between it and the oil outlet of the oil pumping mechanism 3. The hydraulic oil can only be pumped into the accumulator by the oil pumping mechanism 3 and cannot flow back from the accumulator to the oil pumping mechanism 3. At the same time, in order to monitor the internal oil pressure of the accumulator, the accumulator is connected to a pressure sensor 10.

[0042] Example 5

[0043] A specific embodiment of the oil injection control mechanism 5 is provided:

[0044] The oil injection control mechanism 5 includes a normally closed solenoid valve 5.1 connected between the energy storage mechanism 4 and the parking actuator 2, and an oil injection safety device for allowing hydraulic oil to enter the parking actuator 2 in the event of a failure of the normally closed solenoid valve 5.1. The oil injection safety device includes a manual shut-off valve 5.2 connected between the energy storage mechanism 4 and the parking actuator 2 and arranged in parallel with the normally closed solenoid valve 5.1. When energized, the oil injection control mechanism 5 allows hydraulic oil to enter the parking actuator 2 to release the parking brake.

[0045] When the vehicle needs to release the parking brake, but the normally closed solenoid valve 5.1 fails, the manual stop valve 5.2 is opened. Because it is in parallel with the normally closed solenoid valve 5.1, high-pressure brake fluid can flow through the manual stop valve 5.2 to the parking actuator 9. The high-pressure oil compresses the spring, thereby loosening the cable 8 and releasing the parking brake function of the brake 7.

[0046] Example 6

[0047] A specific embodiment of the oil return control mechanism 6 is provided:

[0048] The oil return control mechanism 6 includes a normally open solenoid valve 6.1 connected between the parking actuator 9 and the oil reservoir 1, and an oil return safety device, which prevents hydraulic oil from draining out of the parking actuator 2 if the normally open solenoid valve 6.1 fails. The safety device includes a flow control valve 6.2 connected between the normally open solenoid valve 6.1 and the oil reservoir 1 and arranged in series with the normally open solenoid valve 6.1. When power is off, the oil return control mechanism 6 allows hydraulic oil to drain out of the parking actuator 2, enabling parking brake operation.

[0049] To extend the system lifecycle, two normally open solenoid valves 6.1 are typically arranged in series. During system operation, the two normally open solenoid valves 6.1 switch between on and off states to control the brake circuit. In the event of a failure in normally open solenoid valve 6.1, the oil circuit can be sealed by manually controlling flow control valve 6.2, maintaining the brake fluid pressure in parking actuator 9 and enabling emergency release of the parking brake function.

[0050] Example 7

[0051] The working method based on the above-mentioned electronic parking brake system design is as follows:

[0052] Parking brake control method: De-energize normally closed solenoid valve 5.1 and normally open solenoid valve 6.1, preventing hydraulic oil from entering parking actuator 9. The hydraulic oil in parking actuator 9 flows back to oil reservoir 1. Cable connector 9.2, under the action of elastic member 9.3, tightens cable 8, achieving parking brake 7.

[0053] Parking release control method: energize normally closed solenoid valve 5.1 and normally open solenoid valve 6.1, allowing hydraulic oil to flow into parking actuator 9. This prevents the hydraulic oil in parking actuator 9 from flowing back into oil reservoir 1. The high-pressure oil compresses the spring, loosening cable 8 and releasing brake 7, releasing the parking brake function.

[0054] Long-term parking brake control method: After the vehicle stops and the power is turned off, the normally closed solenoid valve 5.1 forms an open circuit, and the hydraulic oil cannot enter the parking actuator 9. The normally open solenoid valve 6.1 forms a passage, and the hydraulic oil flows back from the parking actuator 9 to the oil storage mechanism 1;

[0055] Temporary parking brake control method: After the vehicle stops, keep the power on and de-energize the normally closed solenoid valve 5.1 and the normally open solenoid valve 6.1. The normally closed solenoid valve 5.1 forms an open circuit, and the hydraulic oil cannot enter the parking actuator 9. The normally open solenoid valve 6.1 forms a passage, and the hydraulic oil flows back from the parking actuator 9 to the oil storage mechanism 1.

[0056] Working method of the energy storage mechanism: The hydraulic oil pressure inside the energy storage mechanism 4 is monitored by the pressure sensor 10. If the hydraulic oil pressure inside the energy storage mechanism 4 is lower than the set value, the hydraulic oil is pumped into the energy storage mechanism 4 through the oil pumping mechanism 3 until the hydraulic oil pressure inside the energy storage mechanism 4 reaches the set value. The oil pumping mechanism 3 stops pumping oil and performs a pressure-maintaining operation on the energy storage mechanism 4 (i.e., preventing the hydraulic oil from entering the parking actuator 9, including closing the manual shut-off valve 5.2 and disconnecting the power supply of the normally closed solenoid valve 5.1).

[0057] When the vehicle needs to release the parking brake, but the normally closed solenoid valve 5.1 fails, the manual stop valve 5.2 is opened, and the brake fluid flows through the manual stop valve 5.2 to the parking actuator 9. The high-pressure oil compresses the spring, loosens the cable 8, and releases the parking brake function of the brake 7.

[0058] When the normally open solenoid valve 6.1 fails, the flow regulating valve 6.2 is manually closed to seal the oil circuit and maintain the brake fluid pressure in the parking actuator 9, thereby realizing the emergency release of the parking brake function.

[0059] In summary, the present invention has innovative designs from system structure to working method, showing significant advantages in reliability, efficiency, energy consumption and other aspects. The specific advantages and effects are as follows:

[0060] 1. The oil injection control unit 5 utilizes a normally closed solenoid valve 5.1 connected in parallel with a manual shutoff valve 5.2. The oil return control mechanism 6 utilizes a normally open solenoid valve 6.1 connected in series with a flow control valve 6.2. In the event of a solenoid valve failure, either the manual shutoff valve 5.2 or the flow control valve 6.2 serves as a backup, ensuring proper parking release and braking functions. Furthermore, the oil return control mechanism 6 includes two normally open solenoid valves 6.1 connected in series, enabling switching between control valves to extend the system lifecycle and further enhance reliability. The parking brake is activated by default with power off. Braking is achieved by tensioning the cable 8 with a spring and other mechanical structures. This ensures safe parking even if the electronic system fails, complying with the fail-safe principle.

[0061] 2. The accumulator 4 stores high-pressure hydraulic oil in advance, releasing energy directly when the parking brake is released, eliminating the need for temporary oil pumping and achieving a rapid response. The pressure sensor 10 monitors the pressure of the accumulator 4 in real time and automatically replenishes pressure when it is low, ensuring that the system is always ready.

[0062] 3. Parking brake operation can be achieved by simply disconnecting the power supply, eliminating the need for continuous power supply. Compared to traditional electric parking systems, this system uses standardized hydraulic components and a simple hydraulic-mechanical linkage structure, eliminating complex transmission components, reducing procurement and maintenance costs, and lowering installation space requirements.

[0063] 4. The hydraulic drive system provides stable and controllable output force, making it suitable for vehicles of varying tonnages, especially large off-road vehicles. Multiple parking control methods (temporary and long-term) can be flexibly selected based on the vehicle's usage scenario, ensuring easy operation and preventing human error.

[0064] It should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be interpreted as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are only limited by the scope of the claims. When using "including", "having" and "comprising" described in this specification, it may also have another part or other parts, and the terms used may generally be singular but may also represent plural forms.

[0065] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and is susceptible to numerous variations. Any simple modifications, equivalent variations, and modifications to the above embodiments based on the technical essence of the present invention shall be deemed to fall within the scope of protection of the present invention.

Claims

1. An electronic parking brake system, comprising an oil storage mechanism (1) for storing parking hydraulic oil, a parking actuator (2) for performing a parking brake operation by discharging hydraulic oil or performing a parking release operation by injecting hydraulic oil, and an oil pumping mechanism (3) for pumping out the hydraulic oil from the oil storage mechanism (1); characterized in that: It also includes an energy storage mechanism (4) for receiving the hydraulic oil pumped out by the oil pump mechanism (3) and storing energy, an oil injection control mechanism (5) for controlling whether the hydraulic oil of the energy storage mechanism (4) enters the parking actuator (2), and an oil return control mechanism (6) for controlling whether the hydraulic oil of the parking actuator (2) flows back to the oil storage mechanism (1). The oil injection control mechanism (5) can allow hydraulic oil to enter the parking actuator (2) to perform a parking release operation in a power-on state, and the oil return control mechanism (6) can allow hydraulic oil to be discharged from the parking actuator (2) to perform a parking brake operation in a power-off state.

2. The electronic parking brake system according to claim 1, wherein: The parking actuator (2) comprises a brake (7), a cable (8) connected to the brake (7), and a parking actuator (9) connected to the cable (8) for receiving or discharging hydraulic oil. The parking actuator (9) comprises an actuator housing (9.1) and a cable connection structure arranged inside the actuator housing. The cable connection structure can release the cable (8) to unlock the brake (7) when the parking actuator (9) is injected with hydraulic oil, or tighten the cable (8) to brake the brake (7) when the parking actuator (9) discharges hydraulic oil.

3. The electronic parking brake system according to claim 2, wherein: The cable connection structure is an elastic structure, comprising a cable connection member (9.2) fixed to the cable (8) and an elastic member (9.3) with both ends respectively fixed to the interior of the actuator housing (9.1) and to the cable connection member (9.2). The cable connection member (9.2) can tighten the cable (8) under the action of the elastic member (9.3), or when hydraulic oil is injected into the parking actuator (9), the hydraulic oil pushes against the cable connection member (9.2) to compress the elastic member (9.3), causing the cable connection member (9.2) to relax the cable (8).

4. The electronic parking brake system according to claim 1, wherein: The oil injection control mechanism (5) comprises a normally closed solenoid valve (5.1) connected between the energy storage mechanism (4) and the parking actuator (2).

5. The electronic parking brake system according to claim 4, wherein: The oil injection control mechanism (5) further comprises an oil injection safety device for allowing hydraulic oil to enter the parking actuator (2) when the normally closed solenoid valve (5.1) fails, the oil injection safety device comprising a manual shut-off valve (5.2) connected between the energy storage mechanism (4) and the parking actuator (2) and arranged in parallel with the normally closed solenoid valve (5.1).

6. The electronic parking brake system according to claim 1, wherein: The oil return control mechanism (6) comprises a normally open electromagnetic valve (6.1) connected between the parking actuator (2) and the oil storage mechanism (1).

7. The electronic parking brake system according to claim 6, wherein: The oil return control mechanism (6) further comprises an oil return safety device for preventing hydraulic oil from being discharged from the parking actuator (2) when the normally open solenoid valve (6.1) fails, the oil return safety device comprising a flow regulating valve (6.2) connected between the normally open solenoid valve (6.1) and the oil storage mechanism (1) and arranged in series with the normally open solenoid valve (6.1).

8. A method for operating an electronic parking brake system according to any one of claims 1 to 7, characterized in that: It includes a parking brake control method and a parking contact control method; The parking brake control method comprises: performing power-off operations on an oil injection control mechanism (5) and an oil return control mechanism (6) so that hydraulic oil cannot enter the parking actuator (2), and causing the hydraulic oil of the parking actuator (2) to flow back to the oil storage mechanism (1). The parking release control method comprises: energizing an oil injection control mechanism (5) and an oil return control mechanism (6) to allow hydraulic oil to enter the parking actuator (2), and preventing the hydraulic oil in the parking actuator (2) from flowing back to the oil storage mechanism (1).

9. The operating method of the electronic parking brake system according to claim 8, characterized in that: The parking brake control method includes a long-term parking brake control method for long-term parking of a vehicle and a temporary parking brake control method for temporary parking of a vehicle; The long-term parking brake control method comprises: after the vehicle stops, the power is turned off, so that the oil injection control mechanism (5) forms an open circuit and the hydraulic oil cannot enter the parking actuator (2), and the oil return control mechanism (6) forms a passage and the hydraulic oil flows back from the parking actuator (2) to the oil storage mechanism (1); The temporary parking brake control method comprises: maintaining a power-on state after the vehicle stops, and performing a power-off operation on the oil injection control mechanism (5) and the oil return control mechanism (6), so that the oil injection control mechanism (5) forms an open circuit and the hydraulic oil cannot enter the parking actuator (2), and the oil return control mechanism (6) forms a passage and the hydraulic oil flows back from the parking actuator (2) to the oil storage mechanism (1).

10. The operating method of the electronic parking brake system according to claim 8, wherein: It also includes an energy storage mechanism working method, which includes: monitoring the hydraulic oil pressure inside the energy storage mechanism (4); if the hydraulic oil pressure inside the energy storage mechanism (4) is lower than a set value, pumping the hydraulic oil into the energy storage mechanism (4) through the oil pumping mechanism (3) until the hydraulic oil pressure inside the energy storage mechanism (4) reaches the set value; the oil pumping mechanism (3) stops pumping oil, and performs a pressure-maintaining operation on the energy storage mechanism (4).

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