Commercial vehicle intelligent parking EPB valve system, EPB valve assembly and intelligent parking control method

Abstract

The present invention relates to the field of intelligent parking for commercial vehicles, and discloses an EPB valve system, an EPB valve assembly and an intelligent parking control method for commercial vehicles, wherein an air inlet is directly connected to a relay valve cavity; one is connected to a first solenoid valve, and another is connected to a pneumatic control valve; the first solenoid valve air inlet gas path is connected to the air inlet, and the air outlet gas path is connected to the control cavity of the pneumatic control valve and connected to a two-way check valve; the control cavity of the pneumatic control valve is connected to the first solenoid valve and the second solenoid valve; the air outlet gas path of the third solenoid valve includes an air path connected to the two-way check valve; the air outlet gas path of the second solenoid valve is connected to the exhaust port; the two-way check valve is connected to the upper cavity of the relay valve, the air outlet for connecting the parking is connected to the relay valve, and the exhaust port is connected to the relay valve. The valve system has the advantages of using fewer parts, convenient control, and no damage to the solenoid valve.

Description

Technical Field

[0001] The present invention relates to the field of electronic parking for commercial vehicles, and in particular to an EPB valve system, an EPB valve assembly and a control method for intelligent parking for commercial vehicles. Background Art

[0002] U.S. Patent US9434366B1 relates to an electronic parking device for heavy-duty vehicles, including commercial vehicles. The electronic parking device for heavy-duty vehicles has an EPB valve and a pneumatic pipeline, which connects the exhaust port of the EPB valve with a spring brake system so that the air pressure of the EPB valve can be applied to the spring brake system to keep the parking brake of the vehicle in a released position. The device also has a normally open solenoid valve, which has an air inlet connected to the pneumatic pipeline. The solenoid valve can be operated to release the air pressure in the pneumatic pipeline, so that the spring brake system applies spring braking force in response to the power failure of the solenoid valve. This parking device can only be parked with EPB, and there is no electric-manual conversion system. It cannot release the parking manually, and it cannot be parked dynamically.

[0003] Chinese patent CN201810005372.1 discloses an electronic parking system for commercial vehicles. The parking brake system combines a parking valve, an ECU and a brake valve to realize a traditional parking function. Its principle and structure are similar to those of passenger cars.

[0004] However, this parking system has the following disadvantages: first, a quick release valve is required, and a pipeline needs to be connected to the cab, which is not conducive to wiring, has large losses, does not utilize integrated control, and is more complicated in vehicle assembly and has higher labor costs.

[0005] The applicant has designed an epb valve, which realizes various functions of intelligent parking through mutual control among a solenoid valve, a control valve and a relay valve in cooperation with an electronic parking brake unit. Summary of the invention

[0006] Aiming at the shortcomings of the electronic parking valve system in the prior art, such as many parts, inconvenient control, and inability to match the intelligent parking system, the present invention provides a commercial vehicle intelligent parking EPB valve system, an EPB valve assembly, and a control method for intelligent parking.

[0007] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0008] The intelligent parking EPB valve system for commercial vehicles includes an electronic control unit, a normally closed first solenoid valve and a second solenoid valve, and a normally open third solenoid valve, and also includes a pneumatic control valve, a relay valve and a two-way check valve. The EPB valve also includes an air inlet for air source pressure to enter, and a check valve is arranged at the air inlet;

[0009] The air path of the air inlet includes three paths, one of which is directly connected to the valve cavity of the relay valve; one of which is connected to the first solenoid valve; and another of which is connected to the pneumatic control valve;

[0010] The first solenoid valve is electrically connected to the electronic control unit, the air inlet path of the first solenoid valve is connected to the air inlet, and the air outlet path is divided into two paths, one path is connected to the control chamber of the pneumatic control valve, and the other path is connected to the two-way one-way valve;

[0011] The control chamber of the pneumatic control valve is connected to the first solenoid valve and the second solenoid valve; the air outlet path of the pneumatic control valve includes an air path connected to the third solenoid valve;

[0012] The third solenoid valve is electrically connected to the electronic control unit, and the gas outlet path of the third solenoid valve includes a gas path connected to the two-way one-way valve;

[0013] The second solenoid valve is electrically connected to the electronic control unit, and the gas outlet path of the second solenoid valve is connected to the exhaust port;

[0014] The control port is connected to the two-way check valve, the two-way check valve is connected to the upper chamber of the relay valve, and the air outlet for connecting the parking is connected to the relay valve. The present invention designs the structure of the epb valve and then uses it in conjunction with the electronic control unit, so that it can realize the function of intelligent parking by controlling the opening and closing of each solenoid valve; and the system does not need to use a parking quick release valve, and occupies little space.

[0015] Preferably, the first solenoid valve and the second solenoid valve are two-position two-way normally closed solenoid valves, and the third solenoid valve is a two-position two-way normally open solenoid valve; the pneumatic control valve is a two-position three-way pneumatic control valve or a two-position two-way pneumatic control valve.

[0016] Preferably, a normally closed manual control valve is bypassed on the air path between the first solenoid valve outlet and the pneumatic control valve, and the manual control valve is connected to the control chamber of the pneumatic control valve. The manual control valve can manually release the parking brake when the automatic parking release fails.

[0017] Preferably, the normally closed manual control valve is a two-position, two-position normally closed manual control valve.

[0018] Preferably, it further includes an air pressure sensor, which is connected to the air outlet for detecting the air pressure of the air outlet, the air pressure sensor is electrically connected to the electronic control unit, and the air outlet is used to be connected to the parking cavity.

[0019] As a preference, the vehicle further comprises a spare air port for connecting the trailer parking brake module, wherein the spare air port is used for realizing electronic parking brake of the trailer when there is also a trailer with the commercial vehicle.

[0020] The present invention provides an EPB valve assembly, which integrates the above-mentioned commercial vehicle intelligent parking EPB valve system.

[0021] The present invention also provides a control method for intelligent parking, including the above-mentioned intelligent parking EPB valve system for commercial vehicles, including parking brake, parking brake release;

[0022] The parking brake is controlled by the following method: when the pneumatic control valve is in the initial state, the pneumatic control valve is in the closed state, the first solenoid valve is not energized, the second solenoid valve and the third solenoid valve are energized, the air pressure at the air inlet enters the relay valve chamber, the compressed air in the relay valve chamber is discharged from the second solenoid valve to the exhaust port, the relay piston returns, and the air outlet is connected to the exhaust port; the compressed air in the parking chamber of the spring brake cylinder is discharged from the exhaust port through the air outlet;

[0023] The parking brake is released by the following method: the first solenoid valve and the third solenoid valve are energized, and the second solenoid valve is not energized. The air pressure of the air source enters the relay valve from the air inlet one way; one way passes through the first solenoid valve; the compressed air through the first solenoid valve enters the upper chamber of the relay valve one way, and one way enters the control chamber of the pneumatic control valve to open the pneumatic control valve. The air of the air source can flow directly through the pneumatic control valve from the air inlet, and then the first solenoid valve is powered off first, and then the second solenoid valve is powered off. The compressed air of the air source enters the upper chamber of the relay piston of the relay valve through the pneumatic control valve and the third solenoid valve in turn to open the relay valve. At this time, the compressed air at the air inlet is discharged from the air outlet into the parking chamber of the spring brake cylinder, and the vehicle brakes are released.

[0024] Preferably, the control method also includes anti-overlapping control: the EPB valve also includes a control port, which is connected to a two-way one-way valve. When the brake pedal is pressed, the air pressure at the control port enters the upper chamber of the relay piston, opens the relay valve, and the compressed air at the air inlet enters the parking chamber of the spring brake cylinder from the air outlet, thereby releasing the vehicle brakes.

[0025] Preferably, an emergency braking control method is also included, the control method includes a control switch, the control switch is an adjustable switch, the opening of the control switch can control the pressure in the parking chamber of the spring brake cylinder, the control switch is electrically connected to an electronic control unit, the electronic control unit obtains the opening of the control switch, calculates the pressure in the parking chamber of the spring brake cylinder at the opening, and then executes the parking action, the air pressure sensor detects the air pressure at the air outlet in real time and transmits it to the electronic control unit, the electronic control unit controls whether to stop the parking brake according to the current air outlet pressure and the pressure corresponding to the calculated control switch.

[0026] The present invention has the following significant technical effects due to the adoption of the above technical solution:

[0027] The present invention designs the structure of the epb valve so that the epb valve can realize functions such as conventional parking and parking switching driving, and the epb valve system eliminates the need for a manual valve, a pipe connected to the cab, and a quick release valve for parking, and has the advantages of low cost, convenient assembly, saving manpower and material costs, and simpler maintenance. In addition, the valve system has the advantages of reliable control, high safety, and long service life of the solenoid valve. At the same time, the epb valve system can not only realize parking brake, brake release, and anti-superposition actions, but also cooperate with other components of the parking system to realize ramp assistance, emergency braking, automatic parking, and drive anti-skid assistance functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a functional diagram of the parking status of the intelligent parking EPB valve system for commercial vehicles.

[0029] Figure 2 It is a driving status function diagram of the intelligent parking EPB valve system of commercial vehicles.

[0030] Figure 3 It is a control schematic diagram of the intelligent parking control system.

[0031] The names of the parts indicated by the numerical labels in the accompanying drawings are as follows: 1—electronic control unit, 2—first solenoid valve, 3—second solenoid valve, 4—third solenoid valve, 5—pneumatic control valve, 6—relay valve, 7—two-way one-way valve, 8—air inlet, 9—one-way valve, 10—control port, 11—exhaust port, 12—air outlet, 13—air pressure sensor. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0033] Example 1

[0034] like Figure 1 and Figure 2 As shown, the intelligent parking EPB valve system for commercial vehicles includes an electronic control unit 1, a normally closed first solenoid valve 2 and a second solenoid valve 3, and a normally open third solenoid valve 4, and also includes a pneumatic control valve 5, a relay valve 6 and a two-way check valve 7. The EPB valve also includes an air inlet 8 for the air source pressure to enter, and a check valve 9 is arranged at the air inlet 8; the electronic control unit 1 is used to receive signals to control each solenoid valve of the EPB valve, so as to realize the corresponding function.

[0035] The air inlet 8 is connected to the air source cylinder, and the air path of the air inlet 8 includes three paths, one of which is directly connected to the valve cavity of the relay valve 6; one is connected to the first solenoid valve 2; and another is connected to the pneumatic control valve 5;

[0036] The first solenoid valve 2 is electrically connected to the electronic control unit 1, the air inlet path of the first solenoid valve 2 is connected to the air inlet 8, and the air outlet path is divided into two paths, one path is connected to the control chamber of the pneumatic control valve 5, and the other path is connected to the two-way check valve 7;

[0037] The control chamber of the pneumatic control valve 5 is connected to the first solenoid valve 2 and the second solenoid valve 3; the air outlet path of the pneumatic control valve 5 includes an air path connected to the third solenoid valve 4;

[0038] The third solenoid valve 4 is electrically connected to the electronic control unit 1 , and the gas outlet path of the third solenoid valve 4 includes a gas path connected to the two-way one-way valve 7 ;

[0039] The second solenoid valve 3 is electrically connected to the electronic control unit 1 , and the air outlet of the second solenoid valve 3 is connected to the exhaust port 11 ; wherein the exhaust port 11 is connected to the outside atmosphere.

[0040] The control port 10 is connected to the two-way check valve 7, the two-way check valve 7 is connected to the upper chamber of the relay valve 6, and the EPB valve also includes an air outlet 12, the air outlet 12 is connected to the relay valve 6, and the exhaust port 11 is connected to the relay valve 6. The air outlet 12 is used to connect to the parking chamber of the spring brake cylinder, so as to input the air pressure of the air source into the parking chamber or discharge the compressed air in the parking chamber to the atmosphere.

[0041] In this embodiment, the first solenoid valve 2 and the second solenoid valve 3 are two-position two-way normally closed solenoid valves, and the third solenoid valve 4 is a two-position two-way normally open solenoid valve; the pneumatic control valve 5 is a two-position three-way pneumatic control valve 5 or a two-position two-way pneumatic control valve 5. The commercial vehicle intelligent parking EPB valve system also includes an air pressure sensor 13, which is connected to the air outlet 12 for detecting the air pressure of the air outlet 12, and the air pressure sensor 13 is electrically connected to the electronic control unit 1, and the air outlet 12 is used to connect to the parking chamber of the spring brake cylinder.

[0042] When the vehicle changes from the driving state to the parking state, the first solenoid valve 2 is not energized, and the second solenoid valve 3 and the third solenoid valve 4 are energized. At this time, the first solenoid valve 2 is in the disconnected state, the second solenoid valve 3 is in the disconnected state, and the third solenoid valve 4 is in the open state; the air pressure at the air inlet 8 enters the chamber of the relay valve 6, and the compressed air in the chamber of the relay valve 6 is discharged from the second solenoid valve 3 to the exhaust port 11, the relay piston returns, and the air outlet 12 is connected to the exhaust port 11; the compressed air in the parking chamber of the spring brake cylinder is discharged from the exhaust port 11 through the air outlet 12. Specifically, the compressed air in the control chamber of the relay valve 6 flows into the second solenoid valve 3 through the two-way check valve 7, and the compressed air flowing out of the second solenoid valve 3 The air is discharged into the atmosphere from the exhaust port 11 through the air path. At this time, the relay piston is pushed to the initial position, and the exhaust port 11 is connected to the relay valve 6 by an air path. When the relay piston returns to the initial position, the air outlet 12 is connected to the exhaust port 11 through the air path on the relay valve 6, so that the compressed air in the parking chamber of the spring brake cylinder is discharged into the atmosphere, thereby achieving the purpose of releasing the brake; at the same time, the compressed air in the control chamber of the pneumatic control valve 5 is also discharged into the atmosphere from the second solenoid valve 3 and the exhaust port 11, and the pneumatic control valve 5 returns to its position. The power-on time of the third solenoid valve 4 depends on the time for the gas in the control chamber of the relay valve 6 chamber to be discharged. This process is generally short and will not cause damage to the solenoid valve.

[0043] When the vehicle needs to switch from the parking state to the driving state, the first solenoid valve 2 and the third solenoid valve 4 are energized, and the second solenoid valve 3 is not energized. At this time, the first solenoid valve 2 is in the open state, the second solenoid valve 3 is in the closed state, and the third solenoid valve 4 is in the closed state; the air source pressure enters the relay valve 6 from the air inlet 8; one way passes through the first solenoid valve 2; the compressed air through the first solenoid valve 2 enters the upper chamber of the relay valve 6 one way, and enters the control chamber of the pneumatic control valve 5 to open the pneumatic control valve 5, so at this time, the air of the air source can flow directly through the pneumatic control valve 5 from the air inlet 8, and then the first solenoid valve 2 is de-energized first, and then the second solenoid valve 3 is de-energized, and the compressed air of the air source enters the upper chamber of the relay piston of the relay valve 6 through the pneumatic control valve 5 and the third solenoid valve 4 in turn to open the relay valve 6, and at this time, the compressed air of the air inlet 8 is discharged from the air outlet 12 into the parking chamber of the spring brake cylinder, and the vehicle is released from the brake. The power-on time of the first solenoid valve 2 and the second solenoid valve 3 is set by the system, and it only needs to be able to open the pneumatic control valve 5, so the power-on time is extremely short. Therefore, this mode has low requirements on the working time of the solenoid valve, so the service life of the solenoid valve is longer. Because the solenoid valve will generate heat and other phenomena when working for a long time, it will damage the service life of the solenoid valve.

[0044] One of the air outlet interfaces of the pneumatic control valve 5 is connected to the exhaust port 11. When the vehicle is in the parking state, if the first solenoid valve 2 leaks or the compressed air at the air inlet 8 flows out from the first solenoid valve 2 due to other reasons, the leaked compressed air is discharged into the atmosphere directly from the control chamber of the pneumatic control valve 5 through the cavity inside the pneumatic control valve 5, thereby ensuring the safety of the EPB valve body and avoiding the situation where the parking fails due to the leakage of the first solenoid valve 2 when the vehicle is in the parking state.

[0045] The control chamber of the pneumatic control valve 5 is externally connected to a normally closed manual control valve 23. The normally closed manual control valve 23 in this embodiment is a two-position two-way normally closed manual control valve. Of course, other types of manual control valves can also be selected as long as manual control can be achieved. The manual control valve is generally used in the case of manual brake release. In this case, the manual control valve is opened, and the compressed air enters the control chamber of the pneumatic control valve 5 through the manual control valve, thereby opening the valve core so that the compressed air at the air inlet 8 can enter the third solenoid valve 4 and then act on the upper chamber of the relay piston of the relay valve 6, so that the air outlet 12 and the air inlet 8 are connected, so as to pressurize the parking chamber and release the brake.

[0046] In this embodiment, there is a first gas circuit connection point 20 and a second gas circuit connection point 21. The first gas circuit connection point 20 has three mutually connected passages, one passage is connected to the gas outlet end of the first solenoid valve 2, one passage is connected to the control chamber of the pneumatic control valve 5, and another passage is connected to the second gas circuit connection point 21; the second gas circuit connection point 21 has four mutually connected gas circuits, one passage is connected to the gas outlet end of the third solenoid valve 4, one passage is connected to the gas inlet end of the second solenoid valve 3, one passage is connected to the two-way one-way valve 9, and the last passage is connected to the first gas circuit connection point 20.

[0047] Example 2

[0048] Different from the embodiment 1, the first solenoid valve 2 and the second solenoid valve 3 in this embodiment are two-position three-way solenoid valves.

[0049] Example 3

[0050] The vehicle also includes a spare air port 22 for connecting the trailer parking brake module. The spare air port 22 is used to realize the electronic parking brake of the trailer part by using the spare air port when there is also a trailer of the commercial vehicle.

[0051] Example 4

[0052] This embodiment provides an EPB valve assembly for intelligent parking of commercial vehicles, and the EPB valve assembly integrates the intelligent parking EPB valve system of the commercial vehicle in Embodiment 1.

[0053] Example 5

[0054] like Figures 1 to 3As shown, the control method of intelligent parking includes the control method of switching from driving state to parking state and the control method of switching from parking state to driving state described in Example 1. The control method also includes anti-overlapping control: the EPB valve also includes a control port 10, and the control port 10 is connected to the two-way check valve 7. When the brake pedal is stepped on, the air pressure of the control port 10 enters the upper chamber of the relay piston, opens the relay valve 6, and the compressed air of the air inlet 8 enters the parking chamber of the spring brake cylinder from the air outlet 12, and the vehicle releases the brake.

[0055] The control method also includes emergency brake control. The intelligent parking system includes a control switch, which is an adjustable switch. The opening of the control switch can control the pressure in the parking chamber of the spring brake cylinder. The control switch is electrically connected to the electronic control unit 1. The electronic control unit 1 obtains the opening of the control switch to calculate the pressure in the parking chamber of the spring brake cylinder at the opening, and then performs the parking action. The air pressure sensor 13 detects the air pressure of the air outlet 12 in real time and transmits it to the electronic control unit 1. The electronic control unit 1 controls whether to stop the parking brake according to the current pressure of the air outlet 12 and the pressure corresponding to the calculated control switch. The pressure value of the air outlet 12 corresponding to the opening of the control switch calculated by the electronic control unit 1 is referenced by the pressure value of the air outlet 12 in the initial state. The pressure value of the air outlet 12 in the initial state is collected and transmitted to the electronic control unit 1 by the air pressure sensor 13.

[0056] In conclusion, the above is only a preferred embodiment of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the patent of the present invention.

Claims

1. A control method for intelligent parking, characterized in that: The EPB valve comprises an electronic control unit (1), a normally closed first solenoid valve (2) and a second solenoid valve (3), and a normally open third solenoid valve (4), and also comprises a pneumatic control valve (5), a relay valve (6), and a two-way check valve (7); the EPB valve also comprises an air inlet (8) for air source pressure to enter, and a check valve (9) is arranged at the air inlet (8); The air circuit of the air inlet (8) includes three circuits, one circuit is directly connected to the valve cavity of the relay valve (6); one circuit is connected to the first solenoid valve (2); and another circuit is connected to the pneumatic control valve (5); The first solenoid valve (2) is electrically connected to the electronic control unit (1); the air inlet path of the first solenoid valve (2) is connected to the air inlet (8); the air outlet path is divided into two paths, one path is connected to the control chamber of the pneumatic control valve (5), and the other path is connected to the two-way check valve (7); The control chamber of the pneumatic control valve (5) is connected to the first solenoid valve (2) and the second solenoid valve (3); the air outlet path of the pneumatic control valve (5) includes an air path connected to the third solenoid valve (4); The third solenoid valve (4) is electrically connected to the electronic control unit (1), and the gas outlet path of the third solenoid valve (4) includes a gas path connected to the two-way one-way valve (7); The second solenoid valve (3) is electrically connected to the electronic control unit (1), and the air outlet of the second solenoid valve (3) is connected to the exhaust port (11); the two-way one-way valve (7) is connected to the upper chamber of the relay valve (6), the air outlet (12) for connecting the parking is connected to the relay valve (6), and the exhaust port (11) is connected to the relay valve (6), including parking brake and parking brake release; The parking brake is controlled by the following method: when the pneumatic control valve (5) is in an initial state, the pneumatic control valve (5) is in a closed state, the first solenoid valve (2) is not energized, the second solenoid valve (3) and the third solenoid valve (4) are energized, the air pressure of the air inlet (8) enters the chamber of the relay valve (6), the compressed air in the chamber of the relay valve (6) is discharged from the second solenoid valve (3) to the exhaust port (11), the relay piston returns to its original position, and the air outlet (12) is connected to the exhaust port (11); the compressed air in the parking chamber of the spring brake cylinder is discharged from the exhaust port (11) through the air outlet (12); The parking brake is released by the following method: the first solenoid valve (2) and the third solenoid valve (4) are energized, and the second solenoid valve (3) is not energized, and the air pressure of the air source enters the relay valve (6) from the air inlet (8); one way passes through the first solenoid valve (2); the compressed air through the first solenoid valve (2) enters the upper chamber of the relay valve (6) and the other way enters the control chamber of the pneumatic control valve (5) to open the pneumatic control valve (5), and the air of the air source can flow directly through the pneumatic control valve (5) from the air inlet (8), and then the first solenoid valve (2) is firstly de-energized, and then the second solenoid valve (3) is de-energized, and the compressed air of the air source enters the upper chamber of the relay piston of the relay valve (6) through the pneumatic control valve (5) and the third solenoid valve (4) in turn to open the relay valve (6), and at this time, the compressed air of the air inlet (8) is discharged from the air outlet (12) into the parking chamber of the spring brake cylinder, and the vehicle brake is released.

2. The intelligent parking control method according to claim 1, characterized in that: It also comprises a control port (10), wherein the control port (10) is connected to a two-way one-way valve (7).

3. The intelligent parking control method according to claim 1, characterized in that: The air outlet path of the pneumatic control valve (5) further comprises an air path connected to the exhaust port (11).

4. The intelligent parking control method according to claim 1, characterized in that: The first solenoid valve (2) and the second solenoid valve (3) are two-position two-way normally closed solenoid valves, the third solenoid valve (4) is a two-position two-way normally open solenoid valve; and the pneumatic control valve (5) is a two-position three-way pneumatic control valve (5).

5. The intelligent parking control method according to claim 1, characterized in that: The control chamber of the pneumatic control valve (5) is externally connected to a normally closed manual control valve (23).

6. The intelligent parking control method according to claim 1, characterized in that: It also includes an air pressure sensor (13), which is connected to the air outlet (12) and is used to detect the air pressure of the air outlet (12). The air pressure sensor (13) is electrically connected to the electronic control unit (1), and the air outlet (12) is used to be connected to the parking chamber.

7. The intelligent parking control method according to claim 1, characterized in that: Also included is a backup air port (22) for connecting to a trailer parking brake module.

8. The intelligent parking control method according to claim 1, characterized in that: The control method further includes anti-overlap control: the EPB valve further includes a control port (10), the control port (10) is connected to the two-way one-way valve (7), when the brake pedal is stepped on, the air pressure of the control port (10) enters the upper chamber of the relay piston, opens the relay valve (6), and the compressed air of the air inlet (8) enters the parking chamber of the spring brake cylinder from the air outlet (12), and the vehicle releases the brake; and also includes an emergency brake control method, the control method includes a control switch, the control switch is an adjustable switch, and the opening of the control switch can control the pressure in the parking chamber of the spring brake cylinder, the control switch is electrically connected to the electronic control unit (1), the electronic control unit (1) obtains the opening of the control switch to calculate the pressure in the parking chamber of the spring brake cylinder at the opening, and then performs the parking action, the air pressure sensor (13) detects in real time and transmits the air pressure of the air outlet (12) to the electronic control unit (1), and the electronic control unit (1) controls whether to stop the parking brake according to the current pressure of the air outlet (12) and the calculated pressure corresponding to the control switch.

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