Hydraulic trailer braking system and hydraulic trailer braking control method

Abstract

The invention provides a hydraulic trailer braking system and a hydraulic trailer braking control method.The hydraulic trailer braking system comprises a pressure oil pipeline, an oil return pipeline, a parking braking hydraulic unit and a traveling braking hydraulic unit; a pressure oil port of the parking brake hydraulic unit and a pressure oil port of the service brake hydraulic unit are respectively connected with a pressure oil pipeline, and an oil return port of the parking brake hydraulic unit and an oil return port of the service brake hydraulic unit are respectively connected with an oil return pipeline; the parking brake hydraulic unit is provided with a parking release oil connector, and the service brake hydraulic unit is provided with a service brake oil connector. According to the invention, the driving, parking and braking comprehensive control of the trailer is realized; when the service braking pipeline is broken, parking braking can be switched; when the parking braking pipeline is broken, parking and driving double braking are carried out; the reliability and the safety coefficient of trailer brake control are improved; emergency parking braking and parking driving double braking can be switched according to different speeds per hour.

Description

Technical Field

[0001] The present invention relates to the technical field of tractor braking hydraulic systems, and particularly relates to a hydraulic trailer braking system and a hydraulic trailer braking control method. Background Art

[0002] Tractors are widely used in agricultural production and usually need to tow trailers for transportation operations. With the general increase in the speed of tractors, the safety level requirements for trailer braking are also getting higher and higher. Hydraulic braking systems have gradually become a research hotspot due to their advantages such as fast response speed, uniform braking force, and simple maintenance.

[0003] However, most of the existing hydraulic braking systems are in the form of single pipelines, and the hydraulic output end is directly connected to the service brake interface of the trailer brake. When the pipeline bursts, trailer braking cannot be performed; at the same time, the parking state of the trailer cannot be controlled simultaneously, and separate control on the trailer is still required during parking; thus, the reliability is insufficient and the safety factor is low.

[0004] In addition, the hydraulic braking system in the form of a single pipeline has a single working mode, cannot achieve braking conditions in the case of intelligent and driverless driving, and does not meet the emergency braking requirements at different speeds. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to improve the reliability of trailer braking.

[0006] The technical solution for the present invention to solve the above technical problem is as follows: The present invention provides a hydraulic trailer braking system, including a pressure oil pipeline, a return oil pipeline, a parking brake hydraulic unit, and a service brake hydraulic unit. The pressure oil ports of the parking brake hydraulic unit and the service brake hydraulic unit are respectively connected to the pressure oil pipeline, and the return oil ports of the parking brake hydraulic unit and the service brake hydraulic unit are respectively connected to the return oil pipeline; a parking release oil interface is provided on the parking brake hydraulic unit, and a service brake oil interface is provided on the service brake hydraulic unit.

[0007] The beneficial effects of the present invention are: By adopting the present invention, the parking brake hydraulic unit provides control pressure oil for the trailer parking brake, and the service brake hydraulic unit provides control pressure oil for the trailer service brake, realizing the integrated control of the trailer's service and parking brakes; when the service brake pipeline bursts, it can be switched to the parking brake to improve braking reliability; when the parking brake pipeline bursts, both the parking and service brakes are maintained to prevent the trailer from moving and avoid damage to the brakes; thus, the safety factor of the trailer brake control is improved. In addition, during emergency braking, the emergency parking brake and the emergency parking and service double brakes can be switched according to different vehicle speeds, with good adaptability, taking into account both reliability and service life. In addition, the control logic of the present invention is clear. By only detecting the states of the handbrake and brake pedal, the pressure at the parking release oil interface, and the pressure at the service brake oil interface, the control conditions can be obtained, facilitating the realization of the braking conditions in the intelligent and driverless scenarios.

[0008] Based on the above technical solutions, the present invention can be further improved as follows.

[0009] Further, the parking brake hydraulic unit includes a parking brake solenoid valve and a first three-way valve. The pressure oil ports of the parking brake solenoid valve and the first three-way valve are both connected to the pressure oil pipeline, the oil return ports of the parking brake solenoid valve and the first three-way valve are both connected to the oil return pipeline, the output port of the parking brake solenoid valve is connected to one end of the valve core of the first three-way valve, and the output port of the first three-way valve is connected to the parking release oil interface.

[0010] By electromagnetic control of the parking brake solenoid valve, the parking brake solenoid valve controls the first three-way valve, which is convenient to operate and facilitates the realization of intelligent control.

[0011] Further, the normal state of the parking brake solenoid valve is the oil return state, and the normal state of the first three-way valve is the output state; the first three-way valve is a three-position three-way valve.

[0012] The release of the parking brake is the normal state, which is convenient to cooperate with the parking handbrake and easy to operate; through the three-position three-way valve, a holding state can be added between the oil return state and the output state of the first three-way valve, facilitating the maintenance of the parking oil pressure.

[0013] Further, the service brake hydraulic unit includes a service brake solenoid valve and a second three-way valve. The pressure oil ports of the service brake solenoid valve and the second three-way valve are both connected to the pressure oil pipeline, the oil return ports of the service brake solenoid valve and the second three-way valve are both connected to the oil return pipeline, the output port of the service brake solenoid valve is connected to one end of the valve core of the second three-way valve, and the output port of the second three-way valve is connected to the service brake oil interface.

[0014] By electromagnetic control of the service brake solenoid valve, the service brake solenoid valve controls the second three-way valve, which is convenient to operate and facilitates the realization of intelligent control.

[0015] Furthermore, the normal state of the service brake solenoid valve is the oil return state; the second three-way valve is a three-position three-way valve, and the normal state of the second three-way valve is the holding state. The service brake oil interface is connected to the other end of the spool of the second three-way valve through a pipeline.

[0016] The release of the service brake is the normal state, which is convenient for cooperating with the brake pedal and easy to operate; when the service brake solenoid valve switches from the output state to the oil return state, the oil pressure at one end of the spool of the second three-way valve is lost. First, it returns to the holding state under the action of its own internal spring, which is convenient for slowly reducing the brake oil pressure; at the same time, the residual oil pressure at the service brake oil interface pushes the other end of the spool of the second three-way valve, causing the second three-way valve to switch to the oil return state, which is convenient for releasing the service brake; improving the braking stability.

[0017] Furthermore, the service brake hydraulic unit further includes an electromagnetic switch valve and an accumulator. The accumulator is connected to one end of the electromagnetic switch valve, and the other end of the electromagnetic switch valve is connected to one end of the spool of the second three-way valve.

[0018] During service braking, the oil fluid output from the service brake solenoid valve to one end of the spool of the second three-way valve can enter the accumulator through the electromagnetic switch valve, which is convenient for storing energy for the accumulator; when the brake pedal is depressed, if the service brake solenoid valve fails, the electromagnetic switch valve opens, and the pressurized oil of the accumulator can push the spool of the second three-way valve through the electromagnetic switch valve, causing the second three-way valve to switch to the output state to achieve service braking, improving the braking reliability.

[0019] Furthermore, the service brake hydraulic unit further includes a pre-switch valve pressure measuring element, which is connected to the pipeline between the electromagnetic switch valve and the accumulator.

[0020] It is convenient to measure the pressure of the accumulator. When the brake pedal is depressed, if there is pressure in the pre-switch valve pressure measuring element but the pressure at the service brake oil interface is too small, it can be judged that the service brake pipeline is ruptured. At this time, an alarm can be issued to indicate the rupture of the service brake pipeline. At the same time, the parking brake hydraulic unit switches to the oil return state, and the oil fluid at the parking release oil interface is depressurized to achieve parking braking; there is no need to check the working status of each valve element one by one, reducing the difficulty of fault judgment, with high accuracy and being convenient for realizing intelligent control.

[0021] Furthermore, a parking brake pressure measuring element is also provided on the parking brake hydraulic unit, and the parking brake pressure measuring element is communicated with the parking release oil interface; a service brake pressure measuring element is also provided on the service brake hydraulic unit, and the service brake pressure measuring element is communicated with the service brake oil interface.

[0022] It is convenient to detect the pressures of the parking release oil interface and the service brake oil interface; when the parking brake is released but the pressure of the parking release oil interface is too low, it can be determined that the parking brake pipeline is broken. At this time, an alarm can be issued to prompt the breakage of the parking brake pipeline. Meanwhile, the parking brake hydraulic unit switches to the oil return state, and the service brake hydraulic unit switches to the output state of the service brake oil interface to maintain both parking and service brakes; there is no need to check the working states of each valve element one by one, which reduces the difficulty of fault judgment, has high accuracy, and is convenient for realizing intelligent control.

[0023] The present invention also provides a hydraulic trailer brake control method, which is implemented based on the above-mentioned hydraulic trailer brake system and includes the following steps: A. Collect the pressure Pz of the parking release oil interface, the pressure Px of the service brake oil interface, the handbrake pulling angle Js, the brake pedal pressing angle Jt, and the vehicle speed v. B. According to the handbrake pulling angle Js, reversely control the output opening of the parking brake hydraulic unit; according to the brake pedal pressing angle Jt, positively control the output opening of the service brake hydraulic unit. C. Preset the handbrake angle limit Jsa and the parking pressure limit Pza. When the handbrake pulling angle Js < the handbrake angle limit Jsa, if the pressure Pz of the parking release oil interface < the parking pressure limit Pza, an alarm is issued to prompt the breakage of the parking brake pipeline. Meanwhile, control the parking brake hydraulic unit to switch to the oil return state, and the service brake hydraulic unit switches to the output state of the service brake oil interface; preset the pedal angle limit Jta and the brake pressure limit Pxa. When the brake pedal pressing angle Jt > the pedal angle limit Jta, if the pressure Px of the service brake oil interface < the brake pressure limit Pxa, an alarm is issued to prompt the breakage of the service brake pipeline. Meanwhile, control the parking brake hydraulic unit to switch to the oil return state. D. Preset the threshold speed va. When the vehicle speed v > 0, if the handbrake pulling angle Js increases, the following judgments and actions are performed: when the vehicle speed v ≤ the threshold speed va, only control the parking brake hydraulic unit to switch to the oil return state; When the vehicle speed v > the threshold speed va, control the parking brake hydraulic unit to switch to the oil return state, and control the service brake hydraulic unit to switch to the output state of the service brake oil interface.

[0024] Further, in step C, for the preset pedal angle limit Jta and the brake pressure limit Pxa, when the brake pedal pressing angle Jt > the pedal angle limit Jta, if the pressure Px of the service brake oil interface < the brake pressure limit Pxa, an alarm is issued to prompt the breakage of the service brake pipeline. Meanwhile, control the parking brake hydraulic unit to switch to the oil return state; specifically include: Collect the energy storage pressure Pn of the energy storage accumulator. If the energy storage pressure Pn > the braking pressure limit value Pxa and the pressure Px at the service brake oil interface < the braking pressure limit value Pxa, an alarm is issued to indicate that the service brake pipeline is ruptured, and at the same time, the parking brake hydraulic unit is controlled to switch to the oil return state; Among them, the service brake hydraulic unit further includes an electromagnetic solenoid valve and an energy storage accumulator. One end of the energy storage accumulator is connected to one end of the electromagnetic solenoid valve, and the other end of the electromagnetic solenoid valve is connected to one end of the spool of the second three-way valve.

[0025] By the energy storage pressure Pn and the pressure Px at the service brake oil interface, it is possible to judge that the service brake pipeline is ruptured, and an alarm and parking brake can be realized; there is no need to check the working state of each valve element one by one, which reduces the difficulty of fault judgment, has high accuracy, and is convenient for realizing intelligent control. Brief Description of the Drawings

[0026] Figure 1 It is a structural schematic diagram of the present invention.

[0027] In the drawings, the technical features represented by each reference numeral are as follows: 1 - Pressure oil pipeline; 2 - Oil return pipeline; 3 - Parking brake hydraulic unit; 31 - Parking brake solenoid valve; 32 - First three-way valve; 4 - Service brake hydraulic unit; 41 - Service brake solenoid valve; 42 - Second three-way valve; 43 - Electromagnetic solenoid valve; 44 - Energy storage accumulator; 45 - Pressure measuring element before the solenoid valve; 5 - Parking release oil interface; 6 - Service brake oil interface; 7 - Fuel tank; 8 - Variable pump; 9 - Parking brake pressure measuring element; 10 - Service brake pressure measuring element. Detailed Embodiment

[0028] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0029] The present invention is described with reference to Figure 1 .

[0030] The present invention provides a hydraulic trailer braking system, including a pressure oil pipeline 1, an oil return pipeline 2, a parking brake hydraulic unit 3, and a service brake hydraulic unit 4. The pressure oil ports of the parking brake hydraulic unit 3 and the service brake hydraulic unit 4 are respectively connected to the pressure oil pipeline 1, and the oil return ports of the parking brake hydraulic unit 3 and the service brake hydraulic unit 4 are respectively connected to the oil return pipeline 2; a parking release oil interface 5 is provided on the parking brake hydraulic unit 3, and a service brake oil interface 6 is provided on the service brake hydraulic unit 4.

[0031] Principle: During installation, the parking release oil interface 5 is used to connect to the parking interface of the trailer brake, and the service brake oil interface 6 is used to connect to the brake interface of the trailer brake; the pressure oil pipeline 1 is used to connect to oil supply equipment such as the variable pump 8, and the variable pump 8 is connected to the fuel tank 7; the return oil pipeline 2 is connected to the fuel tank 7. The trailer brake is a prior art product, which has a parking part and a braking part. Among them, the parking part is in a normally closed (constant braking) state. When there is pressure oil at the parking interface, the pressure oil can open the parking part to release the brake; the braking part is in a normally open state. When there is pressure oil at the brake interface, the pressure oil can close the braking part to the braking state. The specific structure and function implementation means of the trailer brake are irrelevant to the technical problems solved by the present invention. Both the parking brake hydraulic unit 3 and the service brake hydraulic unit 4 can adopt solenoid valves.

[0032] During operation, the pressure oil pipeline 1 supplies oil to the parking brake hydraulic unit 3 and the service brake hydraulic unit 4. The specific states are as follows: When parking (pulling the handbrake): The parking brake hydraulic unit 3 is in a return oil state, and the oil at the parking release oil interface 5 is depressurized through the parking brake hydraulic unit 3 to the return oil pipeline 2.

[0033] When releasing the parking brake (releasing the handbrake): The parking brake hydraulic unit 3 is in an output state for the parking release oil interface 5, providing pressure oil for the parking part of the brake to release the parking state. If the parking brake pipeline ruptures and the handbrake is released but the pressure at the parking release oil interface 5 is too small, the parking brake hydraulic unit 3 can be switched to the return oil state, and at the same time the service brake hydraulic unit 4 is switched to the output state for the service brake oil interface 6 to maintain both parking and service braking.

[0034] When performing service braking (pressing the brake pedal): The service brake hydraulic unit 4 is in an output state for the service brake oil interface 6, providing pressure oil for the braking part of the brake to achieve braking. When the service brake pipeline ruptures and the brake pedal is pressed but the pressure at the service brake oil interface 6 is too small, the parking brake hydraulic unit 3 can be switched to the return oil state, and the oil at the parking release oil interface 5 is depressurized to achieve parking braking.

[0035] During emergency braking (pulling the handbrake while driving, by default the service brake fails and emergency braking is required): If the vehicle speed is below the threshold speed (manually set), only the parking brake hydraulic unit 3 is switched to the return oil state to achieve emergency parking braking; if the vehicle speed is greater than the threshold speed and only relying on the parking brake cannot meet the emergency braking deceleration requirement, the parking brake hydraulic unit 3 is switched to the return oil state, and at the same time the service brake hydraulic unit 4 is switched to the output state for the service brake oil interface 6 to achieve emergency parking and service double braking.

[0036] Preferably, the normal state of the parking brake hydraulic unit 3 is the output state; so that the release of the parking brake is the normal state, which is convenient for cooperating with the parking handbrake and easy to operate. The normal state of the service brake hydraulic unit 4 is the oil return state; so that the release of the service brake is the normal state, which is convenient for cooperating with the brake pedal and easy to operate.

[0037] In summary, by adopting the present invention, the parking brake hydraulic unit 3 provides control pressure oil for the trailer parking brake, and the service brake hydraulic unit 4 provides control pressure oil for the trailer service brake, realizing the comprehensive control of the trailer's service and parking brakes; when the service brake pipeline bursts, it can be switched to the parking brake to improve braking reliability; when the parking brake pipeline bursts, both the parking and service brakes are maintained to prevent the trailer from moving and avoid damage to the brakes; thus, the safety factor of the trailer brake control is improved. In addition, during emergency braking, the emergency parking brake and the emergency parking and service double brakes can be switched according to different speeds, with good adaptability, taking into account reliability and service life. In addition, the control logic of the present invention is clear, and only by detecting the states of the handbrake and the brake pedal, the pressure of the parking release oil interface 5, and the pressure of the service brake oil interface 6, the control conditions can be obtained, which is convenient for realizing the braking conditions in the intelligent and driverless situations.

[0038] Further, the parking brake hydraulic unit 3 includes a parking brake solenoid valve 31 and a first three-way valve 32. The pressure oil ports of the parking brake solenoid valve 31 and the first three-way valve 32 are both connected to the pressure oil pipeline 1. The oil return ports of the parking brake solenoid valve 31 and the first three-way valve 32 are both connected to the oil return pipeline 2. The output port of the parking brake solenoid valve 31 is connected to one end of the spool of the first three-way valve 32. The output port of the first three-way valve 32 is connected to the parking release oil interface 5.

[0039] Example: When the parking brake solenoid valve 31 is in the output state, its pressure oil pushes the spool of the first three-way valve 32 to move, causing the first three-way valve 32 to switch to the oil return state, so that the parking release oil interface 5 is depressurized through the first three-way valve 32 to realize the parking brake. When the parking brake solenoid valve 31 is in the oil return state, one end of the spool of the first three-way valve 32 is depressurized, and the first three-way valve 32 is switched to the output state under the action of its internal spring, and the pressure oil is output to the parking release oil interface 5 through the first three-way valve 32, thereby releasing the parking brake.

[0040] By electromagnetically controlling the parking brake solenoid valve 31, and the parking brake solenoid valve 31 controls the first three-way valve 32, the operation is convenient and it is easy to realize intelligent control.

[0041] Further, the normal state of the parking brake solenoid valve 31 is the oil return state, and the normal state of the first three-way valve 32 is the output state; the first three-way valve 32 is a three-position three-way valve.

[0042] Preferably, the first three-way valve 32 is a three-position three-way solenoid valve.

[0043] The release of the parking brake is in the normal state, which is convenient for cooperation with the parking handbrake and easy to operate; through the three-position three-way valve, a holding state can be added between the oil return state and the output state of the first three-way valve 32, which is convenient for maintaining the parking oil pressure.

[0044] Further, the service brake hydraulic unit 4 includes a service brake solenoid valve 41 and a second three-way valve 42. The pressure oil ports of the service brake solenoid valve 41 and the second three-way valve 42 are both connected to the pressure oil pipeline 1. The oil return ports of the service brake solenoid valve 41 and the second three-way valve 42 are both connected to the oil return pipeline 2. The output port of the service brake solenoid valve 41 is connected to one end of the spool of the second three-way valve 42, and the output port of the second three-way valve 42 is connected to the service brake oil interface 6.

[0045] Example: When the service brake solenoid valve 41 is in the output state, its pressure oil pushes the spool of the second three-way valve 42 to move, so that the second three-way valve 42 is switched to the output state. Thus, the pressure oil is output to the service brake oil interface 6 through the second three-way valve 42 to realize service braking; when the service brake solenoid valve 41 is in the oil return state, the spool of the second three-way valve 42 is depressurized and switched to the oil return state under the action of its internal spring. The pressure oil at the service brake oil interface 6 is depressurized through the second three-way valve 42, which is convenient for releasing the brake.

[0046] By controlling the service brake solenoid valve 41 electromagnetically, and the service brake solenoid valve 41 controls the second three-way valve 42, the operation is convenient and it is easy to realize intelligent control.

[0047] Further, the normal state of the service brake solenoid valve 41 is the oil return state; the second three-way valve 42 is a three-position three-way valve, and the normal state of the second three-way valve 42 is the holding state. The service brake oil interface 6 is connected to the other end of the spool of the second three-way valve 42 through a pipeline.

[0048] Preferably, the second three-way valve 42 is a three-position three-way solenoid valve. The middle position of the spool of the second three-way valve 42 is a closed working position. When working in the middle position, the three ports of the second three-way valve 42 are all closed, so it is in the holding state.

[0049] The release of the service brake is in the normal state, which is convenient for cooperation with the brake pedal and easy to operate; when the service brake solenoid valve 41 is switched from the output state to the oil return state, one end of the spool of the second three-way valve 42 loses oil pressure and first returns to the holding state under the action of its own internal spring, which is convenient for slowly reducing the brake oil pressure; at the same time, the residual oil pressure at the service brake oil interface 6 pushes the other end of the spool of the second three-way valve 42, so that the second three-way valve 42 is switched to the oil return state, which is convenient for releasing the service brake; the braking stability is improved.

[0050] Further, the service brake hydraulic unit 4 further includes an electromagnetic switch valve 43 and an accumulator 44. One end of the accumulator 44 is connected to one end of the electromagnetic switch valve 43, and the other end of the electromagnetic switch valve 43 is connected to one end of the spool of the second three-way valve 42.

[0051] Preferably, the normal state of the electromagnetic switch valve 43 is unidirectional conduction from the other end to the accumulator 44.

[0052] During service braking, the hydraulic oil output from the service brake solenoid valve 41 to one end of the spool of the second three-way valve 42 can enter the accumulator 44 through the electromagnetic switch valve 43, facilitating energy storage for the accumulator 44. When the brake pedal is depressed, if the service brake solenoid valve 41 fails, the electromagnetic switch valve 43 opens, and the pressurized oil in the accumulator 44 can push the spool of the second three-way valve 42 to move, causing the second three-way valve 42 to switch to the output state, achieving service braking and improving braking reliability.

[0053] Further, the service brake hydraulic unit 4 further includes a pre-switch valve pressure measuring element 45, and the pre-switch valve pressure measuring element 45 is connected to the pipeline between the electromagnetic switch valve 43 and the accumulator 44.

[0054] Note: The pressure measuring element can be a pressure gauge, a pressure transmitter, etc.

[0055] It is convenient to measure the pressure of the accumulator 44. When the brake pedal is depressed, if there is pressure in the pre-switch valve pressure measuring element 45 but the pressure at the service brake oil interface 6 is too small, it can be determined that the service brake pipeline is ruptured. At this time, an alarm can be issued to prompt the rupture of the service brake pipeline. At the same time, the parking brake hydraulic unit 3 switches to the oil return state, and the oil at the parking release oil interface 5 is depressurized to achieve parking braking; there is no need to check the working status of each valve element one by one, reducing the difficulty of fault judgment, with high accuracy and facilitating intelligent control.

[0056] Further, a parking brake pressure measuring element 9 is also provided on the parking brake hydraulic unit 3, and the parking brake pressure measuring element 9 is communicated with the parking release oil interface 5; a service brake pressure measuring element 10 is also provided on the service brake hydraulic unit 4, and the service brake pressure measuring element 10 is communicated with the service brake oil interface 6.

[0057] It is convenient to detect the pressures at the parking release oil interface 5 and the service brake oil interface 6; when the parking brake is released but the pressure at the parking release oil interface 5 is too small, it can be determined that the parking brake pipeline is ruptured. At this time, an alarm can be issued to prompt the rupture of the parking brake pipeline. At the same time, the parking brake hydraulic unit 3 switches to the oil return state, and the service brake hydraulic unit 4 switches to the output state of the service brake oil interface 6 to maintain both parking and service braking; there is no need to check the working status of each valve element one by one, reducing the difficulty of fault judgment, with high accuracy and facilitating intelligent control.

[0058] The present invention also provides a hydraulic trailer braking control method, which is implemented based on the above-mentioned hydraulic trailer braking system and includes the following steps: A. Collect the pressure Pz of the parking release oil interface 5, the pressure Px of the service brake oil interface 6, the handbrake pull-up angle Js, the brake pedal depression angle Jt, and the vehicle speed v; In this step: The vehicle speed v can be directly collected by the central controller ECU of the tractor; the parking brake pressure measuring element 9 can be used to collect Pz and transmit it to the ECU, the service brake pressure measuring element 10 can collect Px and transmit it to the ECU, the handbrake angle sensor can collect Js and transmit it to the ECU, and the pedal angle sensor can collect Jt and transmit it to the ECU.

[0059] B. According to the handbrake pull-up angle Js, reversely control the output opening of the parking brake hydraulic unit 3; according to the brake pedal depression angle Jt, positively control the output opening of the service brake hydraulic unit 4; In this step: Through reverse control, the larger the handbrake pull-up angle Js, the smaller the output opening of the parking brake hydraulic unit 3; when the handbrake pull-up angle Js reaches the maximum, the parking brake hydraulic unit 3 is in the oil return state, corresponding to the parking state; when Js = 0, the parking brake hydraulic unit 3 is in the full output state, corresponding to the full release of the parking state.

[0060] Through positive control, the larger the brake pedal depression angle Jt, the larger the output opening of the service brake hydraulic unit 4, corresponding to the service brake state; when Jt = 0, the service brake hydraulic unit 4 is in the oil return state, corresponding to normal driving or normal parking.

[0061] C. Preset the handbrake angle limit value Jsa and the parking pressure limit value Pza. When the handbrake pull-up angle Js < the handbrake angle limit value Jsa, if the pressure Pz of the parking release oil interface 5 < the parking pressure limit value Pza, an alarm is issued to indicate that the parking brake pipeline is broken, and at the same time, the parking brake hydraulic unit 3 is controlled to switch to the oil return state, and the service brake hydraulic unit 4 is controlled to switch to the output state of the service brake oil interface 6; Preset the pedal angle limit value Jta and the brake pressure limit value Pxa. When the brake pedal depression angle Jt > the pedal angle limit value Jta, if the pressure Px of the service brake oil interface 6 < the brake pressure limit value Pxa, an alarm is issued to indicate that the service brake pipeline is broken, and at the same time, the parking brake hydraulic unit 3 is controlled to switch to the oil return state; In this step: Multiple corresponding values of Jsa and Pza can be preset; when Jsa is not preset, the default Jsa is the maximum handbrake pull-up angle. When Js < Jsa, it belongs to the brake release state. When Px < Pxa, it means that the pressure of the parking release oil interface 5 is insufficient, and it can be judged that the parking brake pipeline is broken, preventing the trailer from moving and avoiding damage to the brake.

[0062] In addition, multiple corresponding values of Jta and Pxa can be preset. When Jt > Jta, it is in the service brake state. When Px < Pxa, the brake pressure is insufficient, and the parking brake is switched in time, improving the braking reliability.

[0063] D. Preset a threshold speed va. When the vehicle speed v > 0, if the pulling angle Js of the handbrake increases, the following judgments and actions are performed: When the vehicle speed v ≤ the threshold speed va, only control the parking brake hydraulic unit 3 to switch to the oil return state; When the vehicle speed v > the threshold speed va, control the parking brake hydraulic unit 3 to switch to the oil return state, and control the service brake hydraulic unit 4 to switch to the output state of the service brake oil interface 6.

[0064] In this step: When the vehicle speed v > 0, it is in the driving state. If the pulling angle Js of the handbrake increases, that is, the driver pulls up the handbrake, it is defaulted that emergency braking is required. When the vehicle speed v > the threshold speed va, only relying on the parking brake cannot meet the emergency braking deceleration requirement. Through this step, the emergency parking brake and the emergency parking service double braking are switched according to different vehicle speeds, with good adaptability, taking into account both reliability and service life.

[0065] The specific control process of steps B - D can be realized by directly connecting the ECU to the components of the corresponding unit and sending control signals to them.

[0066] Further, in step C, for the preset pedal angle limit Jta and the brake pressure limit Pxa, when the pedal depression angle Jt > the pedal angle limit Jta, if the pressure Px of the service brake oil interface 6 < the brake pressure limit Pxa, an alarm is issued to indicate that the service brake pipeline is ruptured, and at the same time, control the parking brake hydraulic unit 3 to switch to the oil return state; specifically including: Collect the accumulator pressure Pn of the accumulator 44. If the accumulator pressure Pn > the brake pressure limit Pxa and the pressure Px of the service brake oil interface 6 < the brake pressure limit Pxa, an alarm is issued to indicate that the service brake pipeline is ruptured, and at the same time, control the parking brake hydraulic unit 3 to switch to the oil return state; Among them, the service brake hydraulic unit 4 further includes an electromagnetic solenoid valve 43 and an accumulator 44. One end of the accumulator 44 is connected to one end of the electromagnetic solenoid valve 43, and the other end of the electromagnetic solenoid valve 43 is connected to one end of the spool of the second three - way valve 42.

[0067] Through the accumulator pressure Pn and the pressure Px of the service brake oil interface 6, it is possible to judge that the service brake pipeline is ruptured, realize the alarm and the parking brake; there is no need to check the working state of each valve component one by one, reducing the difficulty of fault judgment, with high accuracy and facilitating the realization of intelligent control.

[0068] In the description of the present invention, it should be understood that if descriptive terms indicating orientation, direction or positional relationship appear, such as: "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated in this specification is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of understanding the present invention and simplifying the description, rather than indicating or implying that the indicated part, element or whole must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the present invention.

[0069] In addition, if descriptive terms indicating order appear, such as: "first", "second", etc., their use in this specification is for the convenience of understanding or simplifying the description. For example, in order to distinguish multiple technical features of the same type or function and having to be mentioned separately, this specification may use the method of prefixing or suffixing descriptive terms of order to distinguish them. Therefore, it cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0070] In the present invention, if descriptive terms indicating the relationship between structure and function are used, such as: "mount", "connect", "join", "fix", etc., unless otherwise clearly specified and defined, they should be understood in a broad sense. For example, "mount", "connect", "join", etc. can be a fixed connection, a detachable connection, or integrated; can be a mechanical connection or an electrical connection; can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements; "fix" can be a fixed connection formed integrally or a detachable fixation through fasteners; can be directly fixed or fixed through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above descriptive terms in the present invention can be understood according to the specific situation, the context, the coherence of the context before and after, etc.

[0071] In the present invention, if there are descriptive terms with an affiliated or connecting meaning, for example, the first feature is "on" or "under" the second feature, unless otherwise clearly specified and defined, it should not be understood restrictively. For example, "on" or "under" can mean that the first and second features are in direct contact, or that the first feature and the second feature are in indirect contact through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above descriptive terms in the present invention can be understood according to the specific circumstances, the context, and the coherence of the context before and after.

[0072] Furthermore, the first feature being "above", "over", and "on top of" the second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "below", "beneath", and "underneath" the second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.

[0073] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments, examples, and the features of different embodiments and examples described in this specification, and these combinations or combinations should fall within the scope summarized by the present invention.

[0074] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can, within the scope of information available in the public domain, make changes, modifications, substitutions, and variations to the above embodiments in combination with the technical revelations given in this application document, and these still fall within the protection scope of this application.

Claims

1. A hydraulic trailer braking system, characterized in that: It includes a pressure oil pipeline (1), a return oil pipeline (2), a parking brake hydraulic unit (3), and a service brake hydraulic unit (4). The pressure oil ports of the parking brake hydraulic unit (3) and the service brake hydraulic unit (4) are respectively connected to the pressure oil pipeline (1), and the return oil ports of the parking brake hydraulic unit (3) and the service brake hydraulic unit (4) are respectively connected to the return oil pipeline (2); a parking release oil interface (5) is provided on the parking brake hydraulic unit (3), and a service brake oil interface (6) is provided on the service brake hydraulic unit (4).

2. The hydraulic trailer braking system according to claim 1, wherein: The parking brake hydraulic unit (3) includes a parking brake solenoid valve (31) and a first three-way valve (32). The pressure oil ports of the parking brake solenoid valve (31) and the first three-way valve (32) are both connected to the pressure oil pipeline (1), the return oil ports of the parking brake solenoid valve (31) and the first three-way valve (32) are both connected to the return oil pipeline (2), the output port of the parking brake solenoid valve (31) is connected to one end of the spool of the first three-way valve (32), and the output port of the first three-way valve (32) is connected to the parking release oil interface (5).

3. The hydraulic trailer braking system according to claim 2, wherein: The normal state of the parking brake solenoid valve (31) is the return oil state, and the normal state of the first three-way valve (32) is the output state; the first three-way valve (32) is a three-position three-way valve.

4. The hydraulic trailer braking system according to claim 1, characterized in that: The service brake hydraulic unit (4) includes a service brake solenoid valve (41) and a second three-way valve (42). The pressure oil ports of the service brake solenoid valve (41) and the second three-way valve (42) are both connected to the pressure oil pipeline (1), the return oil ports of the service brake solenoid valve (41) and the second three-way valve (42) are both connected to the return oil pipeline (2), the output port of the service brake solenoid valve (41) is connected to one end of the spool of the second three-way valve (42), and the output port of the second three-way valve (42) is connected to the service brake oil interface (6).

5. The hydraulic trailer braking system according to claim 4, wherein: The normal state of the service brake solenoid valve (41) is the return oil state; the second three-way valve (42) is a three-position three-way valve, the normal state of the second three-way valve (42) is the holding state, and the service brake oil interface (6) is connected to the other end of the spool of the second three-way valve (42) through a pipeline.

6. The hydraulic trailer braking system according to claim 4, wherein: The service brake hydraulic unit (4) further includes an electromagnetic switch valve (43) and an accumulator (44). One end of the accumulator (44) is connected to the electromagnetic switch valve (43), and the other end of the electromagnetic switch valve (43) is connected to one end of the spool of the second three-way valve (42).

7. The hydraulic trailer braking system according to claim 6, wherein: The service brake hydraulic unit (4) further includes a pre-switch valve pressure measuring element (45), and the pre-switch valve pressure measuring element (45) is connected to the pipeline between the electromagnetic switch valve (43) and the accumulator (44).

8. The hydraulic trailer braking system according to claim 1, characterized in that: A parking brake pressure measuring element (9) is further provided on the parking brake hydraulic unit (3), and the parking brake pressure measuring element (9) is communicated with the parking release oil interface (5); a service brake pressure measuring element (10) is further provided on the service brake hydraulic unit (4), and the service brake pressure measuring element (10) is communicated with the service brake oil interface (6).

9. A hydraulic trailer braking control method, characterized in that: The implementation of the hydraulic trailer braking system according to any one of claims 1-8 includes the following steps: A. Collect the pressure Pz of the parking release oil interface (5), the pressure Px of the service brake oil interface (6), the handbrake pulling angle Js, the brake pedal pressing angle Jt, and the vehicle speed v; B. According to the handbrake pulling angle Js, reversely control the output opening of the parking brake hydraulic unit (3); according to the brake pedal pressing angle Jt, positively control the output opening of the service brake hydraulic unit (4); C. Preset the handbrake angle limit Jsa and the parking pressure limit Pza. When the handbrake pulling angle Js < the handbrake angle limit Jsa, if the pressure Pz of the parking release oil interface (5) < the parking pressure limit Pza, an alarm is issued to indicate that the parking brake pipeline is broken, and at the same time, the parking brake hydraulic unit (3) is controlled to switch to the oil return state, and the service brake hydraulic unit (4) is controlled to switch to the output state of the service brake oil interface (6); Preset the pedal angle limit Jta and the brake pressure limit Pxa. When the brake pedal pressing angle Jt > the pedal angle limit Jta, if the pressure Px of the service brake oil interface (6) < the brake pressure limit Pxa, an alarm is issued to indicate that the service brake pipeline is broken, and at the same time, the parking brake hydraulic unit (3) is controlled to switch to the oil return state; D. Preset the threshold speed va. When the vehicle speed v > 0, if the handbrake pulling angle Js increases, the following judgments and actions are performed: when the vehicle speed v ≤ the threshold speed va, only the parking brake hydraulic unit (3) is controlled to switch to the oil return state; When the vehicle speed v > the threshold speed va, the parking brake hydraulic unit (3) is controlled to switch to the oil return state, and the service brake hydraulic unit (4) is controlled to switch to the output state of the service brake oil interface (6).

10. The hydraulic trailer braking control method according to claim 9, wherein: In step C, for the preset pedal angle limit Jta and the brake pressure limit Pxa, when the brake pedal pressing angle Jt > the pedal angle limit Jta, if the pressure Px of the service brake oil interface (6) < the brake pressure limit Pxa, an alarm is issued to indicate that the service brake pipeline is broken, and at the same time, the parking brake hydraulic unit (3) is controlled to switch to the oil return state; specifically including: Collect the accumulator pressure Pn of the accumulator (44). If the accumulator pressure Pn > the brake pressure limit Pxa and the pressure Px of the service brake oil interface (6) < the brake pressure limit Pxa, an alarm is issued to indicate that the service brake pipeline is broken, and at the same time, the parking brake hydraulic unit (3) is controlled to switch to the oil return state; Among them, the service brake hydraulic unit (4) includes a service brake solenoid valve (41) and a second three-way valve (42). The pressure oil ports of the service brake solenoid valve (41) and the second three-way valve (42) are both connected to the pressure oil pipeline (1). The oil return ports of the service brake solenoid valve (41) and the second three-way valve (42) are both connected to the oil return pipeline (2). The output port of the service brake solenoid valve (41) is connected to one end of the valve core of the second three-way valve (42), and the output port of the second three-way valve (42) is connected to the service brake oil interface (6); The service brake hydraulic unit (4) further includes an electromagnetic solenoid valve (43) and an accumulator (44). One end of the accumulator (44) is connected to the electromagnetic solenoid valve (43), and the other end of the electromagnetic solenoid valve (43) is connected to one end of the spool of the second three-way valve (42).

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