Low-floor tramcar hydraulic braking system and control method and system

Abstract

The invention relates to a hydraulic braking system of a low-floor tramcar and a control method and system of the hydraulic braking system, and belongs to the technical field of railway vehicles. The hydraulic unit comprises an oil tank used for storing hydraulic oil; the oil pump is used for pumping hydraulic oil, an inlet of the oil pump communicates with the oil tank, and an outlet of the oil pump is connected with the clamp through a first oil way; the motor is connected with the oil pump; the outlet end of the throttling hole is connected with the oil tank, the inlet end of the throttling hole is connected with an outlet of the oil pump, and the throttling hole is used for forming hydraulic pressure needed by braking according to the Venturi tube principle. The controller is connected with a vehicle control unit VCU, and the controller is configured to calculate hydraulic pressure needed by braking according to the needed hydraulic braking force sent by the vehicle control unit VCU, calculate the rotating speed of the motor according to the hydraulic pressure needed by braking and control the motor to rotate according to the rotating speed of the motor. The reliability of hydraulic braking is high, and the control precision and usability of an automatic train operation system ATO and station fixed-point parking can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of rail transit technology, and in particular to a hydraulic braking system and control method for a low-floor tram. Background Technology

[0002] With the development of rail transit vehicle technology, low-floor trams have become an important choice for urban transportation construction in many cities because they are suitable for the travel needs of low-capacity areas and integrate new power supply, energy storage, and braking technologies. The low floor of low-floor trams allows for quick passenger boarding and alighting, but this design severely limits the space available for installing equipment underneath the vehicle.

[0003] Traditional air braking systems are too bulky to meet the space requirements of low-floor trams. Hydraulic brakes, with their high operating pressure and compact structure, are easy to install and maintain on the vehicle, making them the preferred braking system for low-floor trams.

[0004] The braking function of current low-floor trams relies on the coordination of electric braking, hydraulic braking, and magnetic track braking, which can effectively meet the deceleration requirements of low-floor trams. However, existing hydraulic braking systems still have significant shortcomings in control modes and reliability. Current hydraulic braking systems employ two control modes for the hydraulic unit based on the electronic brake control unit (EBCU): one is a control mode using a combination of boosting and depressurizing valves (see...). Figure 1 For example, the German patent application with publication number DE102016219314 A1 uses a control mode combining a pressure boosting valve and a pressure reducing valve. Another method is a control mode using a proportional pressure reducing valve (see...). Figure 2 The control modes can be either proportional pressure reducing valves or proportional relief valves. For example, Chinese patent CN109878487 B uses a proportional pressure reducing valve control mode, and Chinese patent application CN 110997433 A uses a proportional relief valve control mode. Both control modes place high demands on valve components, requiring complex control logic and increasing the difficulty of system debugging and maintenance. Furthermore, both require accumulators, which are critical components; however, the lack of effective real-time detection methods for accumulator failures means that failures can easily lead to a decline in system performance, directly affecting the reliability and availability of the hydraulic braking system.

[0005] Furthermore, the existing low-floor trams' hydraulic braking systems employ a distribution management model that prioritizes electric braking and supplements it with hydraulic braking. (See also...) Figure 3The braking force of the entire vehicle is calculated by the vehicle control unit (VCU) in the train control and management system (TCMS) and then distributed to the traction control unit (TCU) and the electronic brake control unit (EBCU). When the network of the electronic brake control unit (EBCU) is interrupted, the hydraulic braking system cannot receive the actual hydraulic braking force demand value requested by the train control and management system (TCMS) and can only output the hydraulic braking force according to the agreed fixed value. This makes it difficult for the vehicle to meet the precise control requirements of the automatic train operation system (ATO) and station fixed-point stopping, affecting operational efficiency and passenger experience. Summary of the Invention

[0006] To address the issues of low reliability in existing technologies, this application provides a hydraulic braking system and control method for low-floor trams. It eliminates the electronic brake control unit (EBCU), accumulator, and valve-type hydraulic components. The vehicle control unit (VCU) directly controls the hydraulic braking system for braking and releasing. Utilizing the Venturi principle, a closed-loop control method is employed where the motor directly controls the output pressure of the oil pump, achieving hydraulic braking for low-floor trams. This simplifies the hydraulic pipeline principle and ensures high reliability of the hydraulic braking system.

[0007] In a first aspect, a hydraulic braking system for a low-floor tram is provided, comprising: The hydraulic unit includes: an oil tank for storing hydraulic oil; an oil pump for pumping hydraulic oil, wherein the inlet of the oil pump is connected to the oil tank and the outlet of the oil pump is connected to the clamp through a first oil circuit; a motor connected to the oil pump; and a throttle orifice, one end of which is connected to the oil tank and the other end of which is connected to the outlet of the oil pump, for generating the hydraulic pressure required for braking through the Venturi principle. The controller is connected to the vehicle control unit (VCU) and is configured to: calculate the required hydraulic pressure for braking based on the required hydraulic braking force sent by the VCU; calculate the motor speed based on the required hydraulic pressure for braking; and control the motor to rotate based on the motor speed to drive the oil pump to rotate.

[0008] In conjunction with the first aspect, in some implementations of the first aspect, the system further includes a first pressure sensor connected to the controller, the first pressure sensor being disposed on the first oil circuit for detecting the actual hydraulic pressure and sending it to the controller.

[0009] In conjunction with the first aspect, in some implementations of the first aspect, the controller is further configured to: calculate the difference between the actual hydraulic pressure and the hydraulic pressure required for braking, and adjust the motor speed through closed-loop feedback control according to the magnitude of the difference until the difference is less than a set threshold.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, the controller is further configured to: calculate the actual hydraulic braking force based on the actual hydraulic pressure and send it to the vehicle control unit (VCU).

[0011] In conjunction with the first aspect, in some implementations of the first aspect, the controller is provided with: The AI ​​module is connected to the vehicle control unit (VCU) and the first pressure sensor, and is used to receive the analog signal of the required hydraulic braking force sent by the vehicle control unit (VCU) and the analog signal of the actual hydraulic braking force sent by the first pressure sensor, and convert them into digital signals. The CPU module is connected to the AI ​​module and is configured to: calculate the hydraulic pressure required for braking based on the required hydraulic braking force; calculate the motor speed based on the required hydraulic braking force; calculate the actual hydraulic braking force based on the actual hydraulic pressure; calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking; and adjust the motor speed based on the difference until the difference is less than a set difference threshold. An MCU module is connected to the CPU module and the motor. The MCU module is configured to control the motor rotation according to the motor speed and feed the motor speed back to the CPU module. The MVB module is connected to the CPU module and the vehicle control unit (VCU), and the MVB module is configured to transmit the actual hydraulic braking force received from the CPU module to the vehicle control unit (VCU).

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the system further includes a first oil filter connected between the outlet of the oil pump and the first oil circuit for filtering hydraulic oil; the inlet of the oil filter is connected to the outlet of the oil pump, and the outlet of the oil filter is connected to the first oil circuit.

[0013] In conjunction with the first aspect, in some implementations of the first aspect, the hydraulic unit further includes a hydraulic valve block, the oil tank, oil pump, motor, and throttle orifice are integrated on the hydraulic valve block, the oil tank is located at the bottom of the hydraulic valve block, and the first oil passage is provided inside the hydraulic valve block; the hydraulic valve block is also provided with a second oil passage, and the throttle orifice is connected to the oil tank at one end through the second oil passage and to the outlet of the oil pump at the other end.

[0014] In conjunction with the first aspect, in some implementations of the first aspect, the controller is further configured to: determine the operating status and fault type of the motor based on the acquired motor temperature, motor speed, motor voltage and motor current, and determine the operating status and fault type of the pressure sensor based on the acquired pressure sensor current.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the controller is further configured to: control the motor to stop working when the motor temperature is greater than a set temperature threshold, or the motor speed suddenly decreases, or the motor voltage is greater than a first set voltage threshold, or the motor voltage is less than a second set voltage threshold, or the motor current is greater than a first set current threshold; the first set voltage threshold is greater than the second set voltage threshold.

[0016] Secondly, a hydraulic braking control method for a low-floor tram is provided, for controlling the hydraulic braking system of the low-floor tram described in the first aspect of this application, comprising the following steps: Acquire vehicle load values, target braking deceleration values, and electric braking force; The required hydraulic braking force is calculated based on the vehicle load value, the target braking deceleration value, and the electric braking force. Calculate the required hydraulic pressure for braking based on the required hydraulic braking force, and calculate the motor speed based on the required hydraulic pressure for braking. The motor rotation is controlled according to the motor speed to drive the oil pump, so that the hydraulic unit outputs actual hydraulic pressure.

[0017] Thirdly, a hydraulic braking control system for a low-floor tram is provided, for controlling the hydraulic braking system of the low-floor tram described in the first aspect of this application, comprising: The vehicle control unit (VCU) is connected to the load sensor, the driver controller, and the traction control unit (TCU). The VCU is configured to calculate the required hydraulic braking force based on the vehicle load value obtained from the load sensor, the target braking deceleration value obtained from the driver controller, and the electric braking force obtained from the traction control unit (TCU). The controller is connected to the vehicle control unit (VCU) and the motor. The controller is configured to: calculate the required hydraulic pressure for braking based on the required hydraulic braking force; calculate the motor speed based on the required hydraulic pressure for braking; and control the motor to rotate based on the motor speed to drive the oil pump to rotate, so that the hydraulic unit outputs the actual hydraulic pressure.

[0018] The beneficial effects of the technical solutions provided in this application include at least the following: The hydraulic braking system and control method for low-floor trams provided in this application are applied to low-floor trams. The electronic brake control unit (EBCU), accumulator, and valve-type hydraulic components are eliminated. The vehicle control unit (VCU) directly controls the hydraulic braking system for braking and releasing. Utilizing the Venturi principle, a closed-loop control method is employed where the motor directly controls the output pressure of the oil pump to achieve hydraulic braking for low-floor trams. This simplifies the electro-hydraulic hybrid braking control during stopping, resulting in faster braking response and closer integration of electric and hydraulic braking. Furthermore, it simplifies the hydraulic pipeline principle, ensuring high reliability of the hydraulic braking system. Simultaneously, it effectively improves the control accuracy and availability of the Automatic Train Operation (ATO) system and station-point stopping.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more apparent, specific embodiments of this application are given below. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the hydraulic unit control principle for the existing low-floor tram hydraulic braking system, which adopts a combination control mode of pressure boosting valve and pressure reducing valve. Figure 2 A schematic diagram of the hydraulic unit control principle for the existing low-floor tram hydraulic braking system using a proportional pressure reducing valve control mode. Figure 3 This is a control principle diagram of the existing low-floor tram hydraulic braking system. Figure 4 This is a schematic diagram of the control principle of the hydraulic unit of the low-floor tram hydraulic braking system described in the embodiments of this application; Figure 5 This is a schematic diagram illustrating the control principle of the hydraulic braking system for the low-floor tram described in the embodiments of this application; Figure 6 This is a schematic flowchart of the hydraulic braking control method for low-floor trams described in an embodiment of this application; Figure 7 This is a flowchart illustrating the method for calculating the required hydraulic braking force based on vehicle load value, target braking deceleration value, and electric braking force as described in an embodiment of this application. Figure 8This is a flowchart illustrating the hydraulic braking control method for low-floor trams described in this application. Figure 9 This is a structural block diagram of the hydraulic braking control system for low-floor trams described in an embodiment of this application.

[0022] In the diagram, 100 is the Vehicle Control Unit (VCU), 200 is the Electronic Brake Control Unit (EBCU), 300 is the Accumulator, 400 is the Clamp, 500 is the Hydraulic Unit, 501 is the Oil Tank, 502 is the Oil Pump, 503 is the Motor, 504 is the Throttle Orifice, 505 is the First Pressure Sensor, 506 is the First Oil Filter, 507 is the Pressure Limiting Valve, 508 is the Second Oil Filter, 509 is the Check Valve, 510 is the Manual Pressure Relief Valve, 511 is the Second Pressure Sensor, 512 is the Pressure Boosting Valve, 513 is the Pressure Reducing Valve, 514 is the Third Oil Filter, 515 is the Third Pressure Sensor, 516 is the Two-Position Two-Way Valve, 517 is the Proportional Pressure Reducing Valve, 600 is the Controller, 601 is the AI ​​Module, 602 is the CPU Module, 603 is the MCU Module, 604 is the MVB Module, and 700 is the Hydraulic Valve Block. Detailed Implementation

[0023] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0024] The prefixes such as "first" and "second" used in this application embodiment are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not constitute unnecessary restrictions due to the use of such prefixes. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0025] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; the term "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0026] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0027] This application provides a hydraulic braking system for low-floor trams, applicable to low-floor trams. See also... Figure 4 , Figure 5 The low-floor tram hydraulic braking system includes: The hydraulic unit 500 includes: an oil tank 501 for storing hydraulic oil; an oil pump 502 for pumping hydraulic oil, wherein the inlet of the oil pump 502 is connected to the oil tank 501 and the outlet of the oil pump 502 is connected to the clamp 400 through a first oil circuit; a motor 503 connected to the oil pump 502; and a throttle orifice 504, one end of which is connected to the oil tank 501 and the other end of which is connected to the outlet of the oil pump 502, for generating the hydraulic pressure required for braking through the Venturi principle. The controller 600 is connected to the vehicle control unit VCU100. The controller is configured to: calculate the required hydraulic pressure for braking based on the required hydraulic braking force sent by the vehicle control unit VCU100; calculate the motor speed based on the required hydraulic pressure for braking; and control the motor 503 to rotate based on the motor speed to drive the oil pump 502 to rotate.

[0028] Specifically, the hydraulic braking force output by the clamp (i.e., the braking force output by the hydraulic unit) ) and hydraulic pressure (i.e., the hydraulic pressure required for braking) There exists a linear relationship between them: Formula 1 In the formula, and This is the inherent coefficient of the clamp.

[0029] The required hydraulic braking force is calculated using the linear relationship described in Formula 1.

[0030] Specifically, the method for calculating the motor speed based on the required hydraulic pressure for braking is as follows: According to the Venturi principle: Formula 2 get: Formula 3 In the formula, This represents the actual traffic volume. The pressure at the inlet of the throttle orifice; The pressure at the outlet of the throttle orifice; The cross-sectional area of ​​the throttling orifice inlet end; The cross-sectional area of ​​the throttling orifice outlet; This refers to the density of the hydraulic oil fluid.

[0031] According to the oil pump flow formula: Formula 4 Formula 5 In the formula, Pump displacement; This refers to the motor speed; For volumetric efficiency, This refers to the hydraulic pressure output by the hydraulic unit.

[0032] Because the outlet end of the throttle orifice is directly connected to the oil tank, Substituting Equations 4 and 5 into Equation 3, the relationship between the hydraulic pressure output by the hydraulic unit and the motor speed is expressed as follows: Formula 6 The motor speed is calculated using Formula 6 based on the required hydraulic pressure for braking.

[0033] In this embodiment, on the one hand, the electronic brake control unit (EBCU) and accumulator are eliminated. The vehicle control unit (VCU) directly controls the hydraulic braking system for braking and releasing, simplifying the electro-hydraulic hybrid braking control during stopping. This results in faster braking response, closer integration of electric and hydraulic braking, and improved system reliability. Simultaneously, it effectively enhances the control accuracy and availability of the Automatic Train Operation (ATO) system and station-time stopping. On the other hand, valve-type hydraulic components are eliminated. A closed-loop control method is used, employing the Venturi principle to directly control the oil pump's output pressure via a motor. This simplifies the hydraulic pipeline, ensuring high reliability of the hydraulic brake and facilitating fault diagnosis and maintenance.

[0034] Specifically, oil pump 502 is connected to oil tank 501 via oil suction pipe. Motor 503 is connected to oil pump 502 via coupling.

[0035] Specifically, the controller 600 is provided with an electrical cover to protect the controller.

[0036] In one embodiment of this application, the hydraulic unit 500 further includes a first pressure sensor 505 connected to the controller 600. The first pressure sensor 505 is located on the first oil circuit and is used to detect the actual hydraulic pressure and send it to the controller 600.

[0037] In one embodiment of this application, the controller 600 is further configured to: calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking. Determine the difference Is it less than or equal to the set threshold? ; in the difference Greater than the set threshold At that time, based on the difference Adjust the motor speed until the difference is reached. Less than the set threshold .

[0038] In this embodiment, the difference between the actual hydraulic pressure and the hydraulic force required for braking is calculated, and it is determined whether the difference is less than or equal to a set threshold. When the difference is greater than the set threshold, the motor speed is adjusted in real time through closed-loop feedback control (such as PID control) according to the difference until the difference is less than the set threshold, so as to ensure that the actual hydraulic braking force quickly approaches the required value and significantly improves the braking accuracy.

[0039] Specifically, classical algorithms such as PID control can be used to calculate the error between the target and actual values ​​in real time. This error is then proportionally amplified, integrally accumulated, and differentially predicted. The three results are then superimposed and output to the actuator, forming a closed-loop control process that can autonomously correct actions and keep the system precisely stable at the target value. In other words, when the actual hydraulic pressure is lower than the target value, according to Formula 6, the motor speed needs to be increased according to the control algorithm. When the actual hydraulic pressure is higher than the target value, according to Formula 6, the motor speed needs to be decreased according to the control algorithm. If the difference is less than or equal to a set threshold, the current speed is maintained. This process is repeated continuously, forming a closed-loop control that ensures the output pressure is infinitely close to the target pressure.

[0040] In one embodiment of this application, the controller 600 is further configured to: calculate the actual hydraulic braking force based on the actual hydraulic pressure and send it to the vehicle control unit VCU100.

[0041] The actual hydraulic braking force is calculated based on the actual hydraulic pressure using the linear relationship described in Formula 1.

[0042] In this embodiment, the actual hydraulic braking force is sent to the vehicle control unit (VCU) to monitor and control the hydraulic braking force of the entire vehicle, thereby realizing the distribution control and management of electric braking force and hydraulic braking force.

[0043] In one embodiment of this application, the controller 600 is provided with: AI module 601 is connected to the vehicle control unit VCU100 and the first pressure sensor 505, and is used to receive the analog signal of the required hydraulic braking force sent by the vehicle control unit VCU100 and the analog signal of the actual hydraulic braking force sent by the first pressure sensor 505 and convert them into digital signals. CPU module 602 is connected to AI module 601. CPU module 602 is configured to: calculate the hydraulic pressure required for braking based on the required hydraulic braking force; calculate the motor speed based on the required hydraulic braking force; calculate the actual hydraulic braking force based on the actual hydraulic pressure; calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking; and adjust the motor speed according to the difference until the difference is less than a set difference threshold. An MCU module 603 is connected to the CPU module 602 and the motor 503. The MCU module 603 is configured to control the rotation of the motor 503 according to the motor speed and to feed back the motor speed to the CPU module 602. MVB module 604 is connected to CPU module 602 and vehicle control unit VCU100. MVB module 604 is configured to transmit the actual hydraulic braking force received from CPU module 602 to vehicle control unit VCU100.

[0044] In this embodiment, the AI ​​module converts the analog signal (such as voltage / current signal) of "required hydraulic braking force" sent by the vehicle control unit (VCU) and the analog signal of "actual hydraulic braking force" fed back by the first pressure sensor into digital signals, providing reliable input for the accurate calculation of the CPU module and avoiding interference and distortion problems in the transmission of analog signals.

[0045] In this embodiment, the CPU module calculates the target hydraulic pressure based on the required hydraulic braking force and then converts it into a motor speed command. At the same time, the actual hydraulic braking force is calculated by back-calculating the actual hydraulic pressure, forming a closed loop of the difference between the "target value and the actual value". The motor speed is adjusted in real time according to the difference (if the difference is too large, the speed is increased to increase the hydraulic pressure) until the difference is less than the threshold, ensuring that the actual hydraulic braking force quickly approaches the required value and significantly improving braking accuracy.

[0046] In this embodiment, the speed command calculated by the CPU module is converted into a motor drive signal (such as a PWM signal), and the actual motor speed is fed back in real time according to the actual hydraulic pressure, forming a two-level closed loop of "command-execution-feedback" to avoid hydraulic pressure instability caused by motor speed fluctuations and ensure the smoothness of the braking process.

[0047] In this embodiment, the "actual hydraulic braking force" calculated by the CPU module is transmitted to the vehicle control unit (VCU) in real time via the MVB bus through the MVB module. This ensures that the vehicle control layer (TCMS / VCU) can monitor the actual output status of the hydraulic brake in real time, which facilitates the VCU to dynamically adjust the distribution ratio of electric braking and hydraulic braking (such as supplementing hydraulic braking force in time when electric braking is insufficient), thereby improving the coordination efficiency of multiple braking systems.

[0048] Compared to the traditional mode that relies on a single network to transmit braking force, in this embodiment, the analog signal is received by the AI ​​module (which can serve as redundancy for network communication) and combined with the digital communication of the MVB module to form a dual signal channel of "analog + digital". This reduces the risk of loss of braking force due to network interruption and is more suitable for the accuracy requirements of braking force for ATO fixed-point stopping in automatic train operation systems.

[0049] In one embodiment of this application, the hydraulic unit 1 further includes a first oil filter 506, which is connected between the outlet of the oil pump 502 and the first oil circuit for filtering hydraulic oil. The inlet of the first oil filter 506 is connected to the outlet of the oil pump 502, and the outlet of the first oil filter 506 is connected to the first oil circuit.

[0050] Impurities mixed into hydraulic oil can alter its viscosity or increase local throttling resistance in the oil circuit, affecting the accuracy of system pressure transmission. In this embodiment, a first oil filter is connected between the oil pump and the first oil circuit. The first oil filter continuously filters the oil, maintaining its cleanliness and stable physical properties, ensuring that the pressure output by the oil pump is accurately transmitted to the downstream oil circuit, avoiding system pressure fluctuations caused by oil contamination, and thus ensuring stable braking force and response speed of the hydraulic brake.

[0051] In one embodiment of this application, the system further includes a hydraulic valve block 700, on which the oil tank 501, oil pump 502, motor 503, throttle orifice 504, and controller 600 are integrated. The oil tank is located at the bottom of the hydraulic valve block, and the first oil passage is provided inside the hydraulic valve block. The hydraulic valve block is also provided with a second oil passage, and the throttle orifice is connected to the oil tank at one end through the second oil passage and to the outlet of the oil pump at the other end.

[0052] In this embodiment, the oil tank, oil pump, motor, throttle orifice, and controller are integrated into the hydraulic valve block, and the first oil circuit and the second oil circuit are integrated within the valve block. The oil tank is located at the bottom of the valve block. This design can achieve structural integration, eliminate a large number of external pipelines and connectors, significantly reduce the system volume, and adapt to the space constraints of low-floor trams.

[0053] Specifically, in a specific embodiment of the first embodiment of this application, the first pressure sensor 505 and the first oil filter 506 are integrated into the hydraulic valve block 700.

[0054] In one embodiment of this application, the controller 600 is further configured to: determine the operating status and fault type of the motor based on the acquired motor temperature, motor speed, motor voltage and motor current, and determine the operating status and fault type of the pressure sensor based on the acquired pressure sensor current.

[0055] Specifically, the motor temperature is detected by a temperature sensor located inside the motor 503. The motor speed is detected by a rotor position sensor located inside the motor 503. The motor voltage is detected by a voltage sensor located on the motor drive circuit of the MCU module 603. The motor current is detected by a current sensor located on the motor drive circuit of the MCU module 603. The temperature sensor, rotor position sensor, voltage sensor, and current sensor respectively send the detected motor temperature, motor speed, motor voltage, and motor current to the MCU module 603 of the controller 600. The MCU module 603 then feeds back the data to the CPU module 602 of the controller 600. The CPU module 602 determines the operating status and fault type of the motor 503 based on the motor temperature, motor speed, motor voltage, and motor current.

[0056] Specifically, the current of the pressure sensor 505 is transmitted from the AI ​​module 601 of the controller 600 to the CPU module 602 of the controller, and the CPU module 602 determines the working status and fault type of the pressure sensor 505 based on the current of the pressure sensor 505.

[0057] In this embodiment, the MCU module 603 detects the motor temperature, motor speed, motor voltage, and motor current signals in real time and feeds them back to the CPU module 602. The CPU module 602 can determine whether the motor is overheating based on the detected motor temperature, whether the motor is stalled based on the detected motor speed, whether the motor is over-voltage or under-voltage based on the detected motor voltage, and whether the motor is overcurrent based on the detected motor current, thereby realizing the detection of the motor's operating status.

[0058] In one embodiment of this application, the controller is further configured to: control the motor to stop working when the motor temperature is greater than a set temperature threshold, or the motor speed suddenly decreases, or the motor voltage is greater than a first set voltage threshold, or the motor voltage is less than a second set voltage threshold, or the motor current is greater than a first set current threshold; the first set voltage threshold is greater than the second set voltage threshold.

[0059] This application embodiment determines whether the motor is in an abnormal state such as overheating, stalled rotor, overvoltage, undervoltage, or overcurrent based on motor temperature, motor speed, motor voltage, and motor current. When an abnormal state is detected, the motor is controlled to stop working, thereby protecting the motor.

[0060] This application provides a hydraulic braking control method for low-floor trams. Figure 6 This is a schematic flowchart illustrating a hydraulic braking control method for a low-floor tram provided in this embodiment. The method is applicable to low-floor trams. The method includes the following steps.

[0061] S1. Obtain vehicle load value, target braking deceleration value, and electric braking force.

[0062] In this embodiment, the load value is obtained through a load sensor, and the target deceleration value and electric braking force are obtained through a braking command.

[0063] S2. Calculate the required hydraulic braking force based on the vehicle load value, the target braking deceleration value, and the electric braking force.

[0064] Specifically, see Figure 7 The method for calculating the required hydraulic braking force based on the vehicle load value, the target braking deceleration value, and the electric braking force is as follows: S21, Vehicle load value Multiply by the target deceleration value To obtain the braking force required for braking ; S22, Apply the required braking force. Reduced braking force Obtain the required hydraulic braking force .

[0065] S3. According to the required hydraulic braking force Calculate the required hydraulic pressure for braking (i.e., the braking force output by the hydraulic unit). ), calculate the motor speed based on the required hydraulic pressure for braking. .

[0066] Specifically, the required hydraulic braking force is calculated using the linear relationship described in Formula 1. The motor speed is then calculated using Formula 6 based on the required hydraulic braking force.

[0067] S4. Control the motor rotation according to the motor speed to drive the oil pump to rotate, so that the hydraulic unit outputs actual hydraulic pressure.

[0068] In one embodiment of this application, the method further includes: Calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking. ; Judge the difference Is it less than or equal to the set threshold? ; in the difference Greater than the set threshold At that time, based on the difference Adjust the motor speed until the difference is reached. Less than the set threshold .

[0069] In this embodiment, the difference between the actual hydraulic pressure and the hydraulic force required for braking is calculated, and it is determined whether the difference is less than or equal to a set threshold. When the difference is greater than the set threshold, the motor speed is adjusted in real time through closed-loop feedback control (such as PID control) according to the difference until the difference is less than the set threshold, so as to ensure that the actual hydraulic braking force quickly approaches the required value and significantly improves the braking accuracy.

[0070] In one embodiment of this application, the method further includes: The actual hydraulic braking force is calculated based on the actual hydraulic pressure and sent to the vehicle control unit (VCU).

[0071] Specifically, the actual hydraulic braking force is calculated based on the actual hydraulic pressure using the linear relationship described in Formula 1.

[0072] In this embodiment, the actual hydraulic braking force is sent to the vehicle control unit (VCU) to monitor and control the hydraulic braking force of the entire vehicle, thereby realizing the distribution control and management of electric braking force and hydraulic braking force.

[0073] For example, see Figure 8 A hydraulic braking control method for low-floor trams includes the following steps: S1. Obtain vehicle load value, target braking deceleration value, and electric braking force; S2, Vehicle load value Multiply by the target deceleration value To obtain the braking force required for braking ; S3, Apply the required braking force. Reduced braking force Obtain the required hydraulic braking force ; S4. Adjust the hydraulic braking force as required. Calculate the required hydraulic pressure for braking; S5. Calculate the motor speed based on the required hydraulic pressure for braking. ; S6. Control the motor rotation according to the motor speed to drive the oil pump to rotate, so that the hydraulic unit outputs actual hydraulic pressure; S7. Calculate the actual hydraulic pressure With the hydraulic pressure required for braking The difference ; S8. Determine the difference. Is it less than or equal to the set threshold? ; in the difference Greater than the set threshold At that time, based on the difference Adjust the motor speed until the difference is reached. Less than the set threshold

[0074] S9. Based on actual hydraulic pressure Calculate the actual hydraulic braking force And send it to the vehicle control unit (VCU).

[0075] The control methods described above in this application are illustrated below with specific examples.

[0076] Scenario: A tram approaches the platform at a certain speed. The driver operates the control handle and issues the "service braking" command, with the goal of bringing the tram to a smooth stop at the designated position on the platform. After passengers board the tram, the driver releases the brakes, with the goal of smoothly accelerating and starting again.

[0077] Braking process: Phase 1: Braking Request and Braking Force Calculation (1) Obtaining vehicle load value: The vehicle control unit (VCU) obtains the current total mass of the vehicle (i.e., vehicle load value) through the load sensor at the bottom of the vehicle when the door was last closed. (and lock it until the next time the door is closed after parking), and lock it until the next update.

[0078] (2) Command issued: The driver pushes the lever to the brake position, the vehicle control unit (VCU) receives the command and determines the target deceleration for this braking action. (e.g., 0.8 m / s²) and electric braking force .

[0079] (3) Calculation of required hydraulic braking force: The vehicle control unit (VCU) calculates the total braking force required based on Newton's second law. , The braking force required for braking Reduced braking force Obtain the required hydraulic braking force .

[0080] Phase Two: Hydraulic Braking System Execution (1) Command transmission: The vehicle control unit (VCU) will transmit the calculated required hydraulic braking force. Simultaneously, the signal is sent to the controller in the hydraulic braking system via an MVB network or hardwired connection.

[0081] (2) Target pressure conversion: The CPU module of the controller receives the required hydraulic braking force. Then, the required hydraulic pressure for braking is calculated according to Formula 1. .

[0082] (3) Speed ​​calculation: The controller calculates the motor speed according to the hydraulic pressure required for braking using formula 6. .

[0083] (4) Closed-loop pressure control (taking PID control as an example): (a) Execution: The MCU module drives the servo motor to precisely match the motor speed. The rotation drives the oil pump to work.

[0084] (b) Feedback: The pressure sensor monitors the actual hydraulic pressure output to the clamp in real time. And continuously send signals back to the controller.

[0085] (c) Comparison and Adjustment: Scenario A (Insufficient Pressure): The sensor detects... < The controller immediately calculates the positive pressure difference. This increases the motor speed, causing the oil pump to output higher pressure, until the actual hydraulic pressure is reached. To catch up with the hydraulic pressure required for braking .

[0086] Scenario B (Overcharge): The sensor detects... > The controller calculates a negative value. And immediately reduce the motor speed to bring the pressure back to the target value.

[0087] Scenario C (Stable Pressure): When and The difference Less than the system set threshold When the speed is ±3 Bar, the controller maintains the current motor speed, the system enters a stable pressure-holding state, and the tram decelerates smoothly.

[0088] The entire process is a dynamic, continuous, and automatic closed-loop feedback control.

[0089] (d) Status feedback: Throughout the process, the controller provides real-time feedback based on the actual hydraulic pressure. Calculate the actual hydraulic braking force It is fed back to the vehicle control unit (VCU) via the MVB module and MVB network, forming a closed loop for vehicle-level braking force monitoring.

[0090] Phase Three: Parking (1) Parking brake: The tram speed drops to zero and stops accurately at the designated position on the platform. The hydraulic pressure required for braking during this period is as follows. According to the required hydraulic braking force The changes are controlled in real time.

[0091] (2) Maintain braking: The system continues to maintain a stable hydraulic pressure to prevent the vehicle from rolling away. At the same time, the total mass of the vehicle is reacquired after the passengers board and close the doors.

[0092] Relief process (taking active clamp as an example): (1) Relief command: The driver pushes the lever to the traction position, and the vehicle control unit (VCU) sends the "required hydraulic braking force" to the hydraulic control system. The instruction to "zero".

[0093] (2) Braking force release: The controller sets the target speed n of the motor to zero, the motor speed decreases according to the set slope, stops rotating, and the oil pump stops supplying pressure. The hydraulic oil in the braking circuit flows back to the oil tank under the action of the clamp return spring, and the actual hydraulic pressure is detected by the pressure sensor. It dropped rapidly to zero.

[0094] (3) Brake release: The calipers fully release the brake disc, and the tram's braking is completely released. The controller sends a "brake released" message to the vehicle control unit (VCU). At this point, the tram can start accelerating.

[0095] This application provides a hydraulic braking control system for low-floor trams, applicable to low-floor trams. Figure 9 The diagram shows the structure of the hydraulic braking control system for a low-floor tram.

[0096] The low-floor tram's hydraulic braking control system includes: The vehicle control unit (VCU100) is connected to the load sensor, the driver controller, and the traction control unit (TCU). The VCU100 is configured to calculate the required hydraulic braking force based on the vehicle load value obtained from the load sensor, the target braking deceleration value obtained from the driver controller, and the electric braking force obtained from the traction control unit (TCU). The controller 600 is connected to the vehicle control unit VCU100 and the motor 503. The controller 600 is configured to: calculate the required hydraulic pressure for braking based on the required hydraulic braking force; calculate the motor speed based on the required hydraulic pressure for braking; and control the motor 503 to rotate based on the motor speed to drive the oil pump 502 to rotate, so that the hydraulic unit 500 outputs the actual hydraulic pressure.

[0097] Specifically, the required hydraulic braking force is calculated using the linear relationship described in Formula 1. The motor speed is then calculated using Formula 6 based on the required hydraulic braking force.

[0098] In one embodiment of this application, the vehicle control unit (VCU100) calculates the required hydraulic braking force based on the vehicle load value, the target braking deceleration value, and the electric braking force by: [The method described is missing from the original text]. Multiply by the target deceleration value To obtain the braking force required for braking The braking force required for braking Reduced braking force Obtain the required hydraulic braking force .

[0099] In one embodiment of this application, the controller 600 is further configured to: calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking. Determine the difference Is it less than or equal to the set threshold? ; in the difference Greater than the set threshold At that time, based on the difference Adjust the motor speed until the difference is reached. Less than the set threshold .

[0100] In one embodiment of this application, the controller 600 is further configured to: calculate the actual hydraulic braking force based on the actual hydraulic pressure and send it to the vehicle control unit VCU100.

[0101] Specifically, the controller 600 calculates the actual hydraulic braking force based on the actual hydraulic pressure using the linear relationship described in Formula 1.

[0102] In one embodiment of this application, see also Figure 4 The controller 600 is equipped with: AI module 601 is connected to the vehicle control unit VCU100 and the first pressure sensor 505, and is used to receive the analog signal of the required hydraulic braking force sent by the vehicle control unit VCU100 and the analog signal of the actual hydraulic braking force sent by the first pressure sensor 505 and convert them into digital signals. CPU module 602 is connected to AI module 601. CPU module 602 is configured to: calculate the hydraulic pressure required for braking based on the required hydraulic braking force; calculate the motor speed based on the required hydraulic braking force; calculate the actual hydraulic braking force based on the actual hydraulic pressure; calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking; and adjust the motor speed according to the difference until the difference is less than a set difference threshold. An MCU module 603 is connected to the CPU module 602 and the motor 503. The MCU module 603 is configured to control the rotation of the motor 503 according to the motor speed and to feed back the motor speed to the CPU module 602. MVB module 604 is connected to CPU module 602 and vehicle control unit VCU100. MVB module 604 is configured to transmit the actual hydraulic braking force received from CPU module 602 to vehicle control unit VCU100.

[0103] Those skilled in the art will recognize that the modules, units, and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0104] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hydraulic braking system for a low-floor tram, characterized in that, include: A hydraulic unit includes: an oil tank for storing hydraulic oil; An oil pump is used to pump hydraulic oil. The inlet of the oil pump is connected to the oil tank, and the outlet of the oil pump is connected to the clamp through a first oil circuit. A motor is connected to the oil pump. A throttle orifice is connected to the oil tank at its outlet end and to the outlet of the oil pump at its inlet end. It is used to generate the hydraulic pressure required for braking through the Venturi principle. The controller is connected to the vehicle control unit (VCU) and is configured to: calculate the required hydraulic pressure for braking based on the required hydraulic braking force sent by the VCU; calculate the motor speed based on the required hydraulic pressure for braking; and control the motor to rotate based on the motor speed to drive the oil pump to rotate.

2. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The system also includes a first pressure sensor connected to the controller. The first pressure sensor is located on the first oil line and is used to detect the actual hydraulic pressure and send it to the controller.

3. The low-floor tram hydraulic braking system according to claim 2, characterized in that, The controller is also configured to: calculate the difference between the actual hydraulic pressure and the hydraulic pressure required for braking, and adjust the motor speed according to the difference until the difference is less than a set threshold.

4. The low-floor tram hydraulic braking system according to claim 3, characterized in that, The controller is also configured to calculate the actual hydraulic braking force based on the actual hydraulic pressure and send it to the vehicle control unit (VCU).

5. The low-floor tram hydraulic braking system according to claim 4, characterized in that, The controller is equipped with: The AI ​​module is connected to the vehicle control unit (VCU) and the first pressure sensor, and is used to receive the analog signal of the required hydraulic braking force sent by the vehicle control unit (VCU) and the analog signal of the actual hydraulic braking force sent by the first pressure sensor, and convert them into digital signals. A CPU module is connected to the AI ​​module. The CPU module is configured to: calculate the hydraulic pressure required for braking based on the required hydraulic braking force; calculate the motor speed based on the required hydraulic braking force; and calculate the actual hydraulic braking force based on the actual hydraulic pressure. Calculate the difference between the actual hydraulic pressure and the hydraulic force required for braking, and adjust the motor speed according to the difference until the difference is less than the set difference threshold. An MCU module is connected to the CPU module and the motor. The MCU module is configured to control the motor rotation according to the motor speed and feed the motor speed back to the CPU module. The MVB module is connected to the CPU module and the vehicle control unit (VCU), and the MVB module is configured to transmit the actual hydraulic braking force received from the CPU module to the vehicle control unit (VCU).

6. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The system further includes a first oil filter, which is connected between the outlet of the oil pump and the first oil circuit for filtering hydraulic oil; the inlet of the oil filter is connected to the outlet of the oil pump, and the outlet of the oil filter is connected to the first oil circuit.

7. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The hydraulic unit also includes a hydraulic valve block. The oil tank, oil pump, motor, and throttle orifice are integrated on the hydraulic valve block. The oil tank is located at the bottom of the hydraulic valve block. The first oil passage is located inside the hydraulic valve block. The hydraulic valve block also has a second oil passage. The throttle orifice is connected to the oil tank at one end through the second oil passage and to the outlet of the oil pump at the other end.

8. A hydraulic braking system for a low-floor tram according to claim 1, characterized in that, The system also includes a fault detection unit connected to the controller, which is used to detect motor temperature, motor speed, motor voltage and motor current and send them to the controller.

9. A hydraulic braking control method for a low-floor tram, used to control the hydraulic braking system of the low-floor tram as described in claims 1 to 8, characterized in that, Including the following steps: Acquire vehicle load values, target braking deceleration values, and electric braking force; The required hydraulic braking force is calculated based on the vehicle load value, the target braking deceleration value, and the electric braking force. Calculate the required hydraulic pressure for braking based on the required hydraulic braking force, and calculate the motor speed based on the required hydraulic pressure for braking. The motor rotation is controlled according to the motor speed to drive the oil pump, so that the hydraulic unit outputs actual hydraulic pressure.

10. A hydraulic braking control system for a low-floor tram, used to control the hydraulic braking system of the low-floor tram as described in claims 1 to 8, characterized in that, include: The vehicle control unit (VCU) is connected to the load sensor, the driver controller, and the traction control unit (TCU). The VCU is configured to calculate the required hydraulic braking force based on the vehicle load value obtained from the load sensor, the target braking deceleration value obtained from the driver controller, and the electric braking force obtained from the traction control unit (TCU). A controller, connected to the vehicle control unit (VCU) and the motor, is configured to: calculate the required hydraulic pressure for braking based on the required hydraulic braking force, and calculate the motor speed based on the required hydraulic pressure for braking. The motor rotation is controlled according to the motor speed to drive the oil pump, so that the hydraulic unit outputs actual hydraulic pressure.

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