Urban rail vehicle braking control method and system

Abstract

The present invention relates to a braking control method and system for urban rail vehicles, comprising the following steps: when a vehicle triggers emergency braking, calculating a braking force requirement and applying electro-pneumatic braking to the vehicle based on the braking force requirement; during the application process, periodically calculating the vehicle's current speed, theoretical braking distance, and actual braking distance; comparing the theoretical and actual braking distances in each calculation cycle; and based on the comparison result, continuously applying electro-pneumatic braking until the vehicle speed drops to a predetermined speed threshold, controlling the braking system to apply pure air braking to the vehicle until it stops, or immediately ceasing application of electric braking based on the comparison result and controlling the braking system to apply pure air braking to the vehicle until it stops. The present invention incorporates electric braking into emergency braking, and through closed-loop management of the actual braking effect of the electro-pneumatic braking, minimizes brake disc and caliper wear while ensuring safe vehicle parking, thereby effectively reducing vehicle maintenance and repair costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of rail vehicles, and in particular relates to a braking control method and system for urban rail vehicles. Background Art

[0002] In the prior art, urban rail vehicles are usually equipped with a traction system and a braking system to realize the vehicle's braking function. The traction system and the braking system provide two braking modes: electric braking and air braking respectively.

[0003] At present, electronic control is usually used in the normal braking and rapid braking processes of vehicles. The braking system is responsible for calculating and distributing the braking force requirements, and based on the available electric braking force feedback from the traction system, the required braking force is preferentially distributed to the traction system. The insufficient part is supplemented by air braking.

[0004] Emergency braking offers a far greater level of safety than regular braking and rapid braking, serving as the ultimate guarantee for safe vehicle stopping. Currently, emergency braking is typically implemented using solenoid valve control, where the vehicle's emergency brake hardwire de-energizes the emergency valve in the braking system, thereby applying pure air braking. While this pure air braking method ensures rapid vehicle stopping in emergencies, the sudden application of pure air braking during high-speed train operation can lead to increased wear on the brake calipers and brake discs. Over time, excessive wear on the brake calipers and brake discs increases vehicle maintenance costs and reduces vehicle operating efficiency and service life.

[0005] Therefore, there is an urgent need for a brake control method that can improve the safety of electronic control methods and introduce electric braking into emergency braking to ensure that the vehicle can be safely stopped during emergency braking while minimizing the wear of the brake caliper and brake disc. Summary of the Invention

[0006] The purpose of the present invention is to solve one of the above technical problems and provide a braking control method and system for urban rail vehicles. By improving the safety of the electronic control method and introducing electric braking into emergency braking, it ensures that the vehicle can be safely stopped during emergency braking and the wear of the brake caliper and brake disc can be minimized.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A braking control method for an urban rail vehicle, wherein the urban rail vehicle includes a traction system and a braking system, each for applying electric braking and air braking, and the control method includes the following steps:

[0009] Determine whether the current vehicle is in an emergency braking state;

[0010] When the vehicle is judged to be in an emergency braking state, the vehicle braking force requirement is calculated based on the vehicle's current load;

[0011] Based on the vehicle's braking force demand, the electric braking demand and the air braking demand are distributed, thereby controlling the traction system and the braking system to apply electric-air composite braking to the vehicle;

[0012] During the application of electro-pneumatic brakes, the current speed of the vehicle, the theoretical braking distance required for the vehicle to be decelerated from the initial speed to the current speed, and the actual braking distance required for the vehicle to be decelerated from the initial speed to the current speed are periodically calculated;

[0013] Each calculation cycle compares the theoretical braking distance with the actual braking distance;

[0014] If the actual braking distance is less than or equal to the theoretical braking distance, it is determined that the cycle is relatively qualified; otherwise, it is determined that the cycle is relatively unqualified;

[0015] The duration of the unqualified cycles is accumulated. If the accumulated duration is always less than or equal to the predetermined time threshold t1, the traction system and the braking system are continuously controlled to apply electric-pneumatic composite braking until the vehicle speed drops to the predetermined speed threshold v0. The electric braking is then stopped, and the braking system is controlled to apply pure air braking to stop the vehicle.

[0016] If the accumulated time is longer than the predetermined time threshold t1, the electric brake is immediately stopped and the brake system is controlled to apply pure air brake to the vehicle until the vehicle stops.

[0017] In some embodiments of the present invention, the method for calculating the current speed of a vehicle includes the following steps:

[0018] Periodically collecting at least four speed pulse signals and respectively calculating at least four shaft speeds of the current period;

[0019] When the effective axle speeds among at least four axle speeds are not less than two, the average value of the effective axle speeds is taken as the current speed of the vehicle.

[0020] In some embodiments of the present invention, a method for calculating a theoretical braking distance for a vehicle to be reduced from an initial speed to a current speed includes the following steps:

[0021] Obtain the preset vehicle emergency braking average deceleration index a1 and the vehicle guaranteed emergency braking rate a x , a predetermined time threshold t1 at which the electro-pneumatic composite brake fails to meet the predetermined emergency braking distance requirement, and a predetermined time t2 at which the electro-pneumatic composite brake switches to pure air brake;

[0022] Calculate the initial velocity v1 of the vehicle when emergency braking is triggered;

[0023] Based on the initial speed v1 and the vehicle's guaranteed emergency braking rate ax Calculate the safety protection braking distance S from the initial speed v1 to the parking of the vehicle during emergency braking x :

[0024] S x =v1 2 / (2×a x );

[0025] Based on the safety protection braking distance S x Calculate the average deceleration a that the vehicle needs to achieve by pure air braking y :

[0026] a y =v1 2 / (2×(S x -v 1× t));

[0027] Wherein, time t is the sum of the predetermined time threshold t1 and the predetermined time t2;

[0028] In the vehicle emergency braking average deceleration index a1 and average deceleration a y Select the target deceleration a of electric brake T ;

[0029] Calculate the vehicle's current speed v2;

[0030] Based on the initial velocity v1, current velocity v2 and target deceleration a of the electric brake T Calculate the theoretical braking distance of the vehicle from the initial speed v1 to the current speed v2:

[0031] S T =(v1 2 -v2 2 ) / (2×a T ).

[0032] In some embodiments of the present invention, a method for calculating an actual braking distance of a vehicle from an initial speed to a current speed includes the following steps:

[0033] Periodically collecting at least four speed pulse signals and respectively calculating at least four shaft speeds of the current period;

[0034] When the effective shaft speed is not less than two of at least four shaft speeds, the maximum number of pulses corresponding to the effective shaft speed is taken as the number of speed pulses in the current cycle.

[0035] Calculate the actual braking distance of the vehicle in the current cycle based on the number of speed pulses in the current cycle, the number of gears of the onboard speed sensor, and the wheel diameter;

[0036] The actual braking distance of the vehicle in each cycle is continuously accumulated to obtain the actual braking distance of the vehicle from the initial speed to the current speed.

[0037] In some embodiments of the present invention, the following steps are included:

[0038] Preset the braking force build-up time t0;

[0039] After the emergency brake is triggered and the braking force buildup time t0 has passed, the vehicle's current speed, the theoretical braking distance from the initial speed to the current speed, and the actual braking distance from the initial speed to the current speed are periodically calculated.

[0040] In some embodiments of the present invention, the following steps are further included:

[0041] The method for allocating electric brake force requirements and air brake force requirements based on vehicle brake force requirements includes the following steps:

[0042] Obtain the available electric braking force of the traction system;

[0043] When the available electric braking force is greater than the vehicle braking force demand, all the vehicle braking force demand is allocated to the electric braking force demand;

[0044] When the available electric braking force is less than the vehicle braking force demand, the vehicle braking force demand is distributed into an electric brake demand equal to the available electric braking force and an air brake demand equal to the difference between the vehicle braking force demand and the available electric brake force.

[0045] Some embodiments of the present invention further provide a braking control system for an urban rail vehicle, comprising: a traction system, a braking system, and an emergency braking management device;

[0046] The traction system is used to apply electric brakes to the vehicle and includes a traction control unit;

[0047] The brake system is used to apply air brakes to the vehicle and includes a brake control unit and an emergency valve;

[0048] The emergency brake management device is connected to the vehicle load sensor, vehicle speed sensor, and emergency valve of the brake system through hard wires, and is communicated with the traction control unit of the traction system and the brake control unit of the brake system through the train network;

[0049] The emergency brake management device runs the emergency brake management software, which includes:

[0050] An emergency braking state judgment module is used to judge whether the vehicle is currently in an emergency braking state based on the collected emergency braking instructions;

[0051] A braking force demand calculation module, used to calculate the braking force demand of the vehicle based on the vehicle load;

[0052] a braking force demand allocation module, configured to allocate the calculated braking force demand into an electric braking demand and an air braking demand, and send the electric braking demand and the air braking demand to the traction control unit and the brake control unit, respectively, so that the traction control unit and the brake control unit control corresponding execution units to apply electric-air composite braking;

[0053] The periodic calculation module is used to periodically calculate the current speed of the vehicle, the theoretical braking distance of the vehicle from the initial speed to the current speed, and the actual braking distance of the vehicle from the initial speed to the current speed.

[0054] The braking distance comparison module is used to compare the theoretical braking distance with the actual braking distance in each calculation cycle; if the actual braking distance is less than or equal to the theoretical braking distance, the cycle is judged to be qualified; otherwise, the cycle is judged to be unqualified, and the duration of the unqualified cycle is accumulated;

[0055] The brake conversion control module is used to continuously control the traction control unit and the brake control unit to apply electric-pneumatic composite braking when the cumulative duration of the unqualified period is less than or equal to the predetermined time threshold until the vehicle speed drops to the predetermined speed threshold, stop applying the electric brake, and control the emergency valve to apply air braking to the vehicle until it stops; when the cumulative duration of the unqualified period is greater than the predetermined time threshold, immediately control the traction control unit and the brake control unit to stop applying the electric-pneumatic composite braking, and control the emergency valve to apply pure air braking to the vehicle until it stops.

[0056] In some embodiments of the present invention, the period calculation module includes:

[0057] A vehicle speed calculation unit, configured to periodically collect at least four speed pulse signals, calculate at least four axle speeds in a current cycle, and calculate an average of at least two effective axle speeds as the current speed of the vehicle;

[0058] a theoretical braking distance calculation unit, configured to calculate the theoretical braking distance required for the vehicle to be reduced from its initial speed to its current speed based on a preset average deceleration index for emergency braking of the vehicle, a guaranteed emergency braking rate of the vehicle, a predetermined time threshold at which the electro-pneumatic composite braking fails to meet a predetermined emergency braking distance requirement, a predetermined time for the electro-pneumatic composite braking to switch to pure air braking, and the calculated current speed of the vehicle;

[0059] The actual braking distance calculation unit is used to take the maximum number of speed pulses corresponding to at least two effective shaft speeds in the current cycle as the number of speed pulses in the current cycle, calculate the actual braking distance of the vehicle in the current cycle based on the number of speed pulses in the current cycle, the number of gears of the on-board speed sensor, and the wheel diameter, and continuously accumulate the actual braking distance of the vehicle in each cycle to obtain the actual braking distance of the vehicle from the initial speed to the current speed.

[0060] In some embodiments of the present invention, the emergency brake management device includes a main control board, a digital input board, an analog input board, a digital output board, and a network communication board connected to the same backplane;

[0061] The digital input board is used to collect emergency braking commands and speed pulse signals sent by the vehicle speed sensor;

[0062] The analog input board is used to collect the load analog signal sent by the vehicle-mounted sensor;

[0063] The digital output board is used to send emergency valve drive instructions to the brake system to control the brake system to apply pure air brakes;

[0064] The network communication board is used to receive available electric braking force information sent by the traction system, and to send air braking requirements to the brake control unit and electric braking requirements to the traction control unit, so as to control the corresponding execution units to apply electric-air composite braking through the traction control unit and the brake control unit;

[0065] The main control board is used to determine whether the vehicle is currently in an emergency braking state, calculate the vehicle's braking force demand, calculate the braking force demand distribution value, calculate the vehicle's current speed, the theoretical braking distance of the vehicle from the initial speed to the current speed, the actual braking distance of the vehicle from the initial speed to the current speed, and control the traction system and braking system to apply electro-pneumatic composite braking or pure air braking based on the comparison results of the theoretical braking distance and the actual braking distance.

[0066] In some embodiments of the present invention, the main control board, digital input board, analog input board, and digital output board all adopt a two-by-two-out-of-two architecture design, and perform hardware two-out-of-two voting when collecting signals or outputting instructions.

[0067] In some embodiments of the present invention, a fault handling module is further included, which is used to detect its own working status in real time when the emergency braking management device determines that the vehicle is in an emergency braking state, and immediately stop applying electric braking when it determines that a fault occurs, and control the braking system to apply pure air braking to the vehicle until it stops.

[0068] The beneficial effects of the present invention are:

[0069] 1. The braking control method provided by the present invention incorporates electric braking into the emergency braking control process. When a vehicle performs emergency braking, the traction brake unit and the brake control unit first control the corresponding actuator to apply electro-pneumatic braking. During the electro-pneumatic braking process, closed-loop management of the actual braking effect is performed. The braking strategy is adjusted based on the actual braking effect. Compared with the existing emergency braking method that directly controls the emergency valve to implement pure air braking, this method minimizes brake disc and brake caliper wear while ensuring safe vehicle parking, thereby effectively reducing vehicle maintenance costs.

[0070] 2. The braking control method provided by the present invention has strong versatility and is applicable to emergency braking management of urban rail vehicles of different models and different braking modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0072] Figure 1 This is a flow chart of a braking control method for urban rail vehicles;

[0073] Figure 2 An electrical interface diagram of the emergency brake management device provided in an embodiment of the present application;

[0074] Figure 3 A schematic diagram of the structure of a two-stage emergency brake application link provided in an embodiment of the present application;

[0075] Figure 4 A schematic diagram of the structure of the emergency brake management device provided in an embodiment of the present application;

[0076] Figure 5 A control schematic diagram of the emergency brake management device provided in an embodiment of the present application;

[0077] Figure 6 A flowchart of the emergency brake management device provided in an embodiment of the present application;

[0078] Figure 7 A schematic diagram of the structure of the digital input board provided in an embodiment of the present application;

[0079] Figure 8 A schematic diagram of the structure of the digital output board provided in an embodiment of the present application;

[0080] Figure 9 A schematic diagram of the structure of the main control board provided in an embodiment of the present application. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts are within the scope of protection of this application.

[0082] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0083] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0084] The technical solution of the present invention is described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0085] As attached Figure 1 -Attached Figure 9 As shown, in an exemplary embodiment of a braking control method for a rail vehicle of the present invention, the rail vehicle includes a traction system and a braking system, which are used to apply electric braking and air braking respectively. The braking control method includes the following steps.

[0086] S1: Install emergency brake management equipment on urban rail vehicles.

[0087] As attached Figure 2 As shown, the emergency brake management device is connected to the vehicle load sensor, vehicle speed sensor, and emergency valve of the brake system through hard wires, and is communicatively connected to the traction control unit of the traction system and the brake control unit of the brake system through the train network.

[0088] Specifically, as attached Figure 4 As shown, the emergency brake management device includes at least a main control board, a digital input board, an analog input board, a digital output board and a network communication board connected to the same backplane.

[0089] The digital input board collects emergency braking commands and speed pulse signals from the vehicle's speed sensor. The analog input board collects analog load signals from the vehicle's sensors. The digital output board sends emergency valve actuation commands to the braking system, controlling the system to apply pure air braking. The network communication board sends electric braking requests and air braking requests to the traction system and braking system, respectively, controlling the application of electric-pneumatic combined braking in these systems. It also receives feedback from the traction system on available electric braking force. The main control board performs data processing and calculations.

[0090] Based on the above structure, as shown in the attached Figure 3 As shown, the emergency brake management device divides the emergency brake application mode into two levels.

[0091] Among them, the application link of the first-level emergency brake is the emergency brake management device that controls the traction control unit of the traction system and the brake control unit of the brake system to apply electro-pneumatic composite braking. The application link of the first-level emergency brake depends on the traction control unit and the brake control unit. Although the safety of the emergency brake management device is high, the safety of the traction control unit and the brake control unit is relatively low. Therefore, the safety of the first-level emergency brake is relatively low and the safe braking distance cannot be guaranteed.

[0092] The Level 2 emergency brake application link involves the emergency brake management device controlling the brake system's emergency valve to apply pure air braking. This link relies on the brake system's emergency valve, which is highly reliable. The highly secure emergency brake management device and the highly reliable emergency valve work together to achieve highly secure Level 2 emergency braking, ensuring a safe braking distance.

[0093] The present invention manages two-stage emergency braking, thereby minimizing the wear of the brake caliper and the brake disc while ensuring safe parking of the vehicle during emergency braking.

[0094] S2: Determine whether the current vehicle is in an emergency braking state.

[0095] In some embodiments of the present invention, a specific method for determining whether a vehicle is currently in an emergency braking state includes:

[0096] Use the digital input board to acquire emergency brake commands periodically or in real time from hard wire.

[0097] When the digital input board detects that the emergency braking command is high, the main control board determines that the vehicle is in a non-emergency braking state.

[0098] When the digital input board detects that the emergency braking command changes from high level to low level, the main control board determines that the vehicle enters the emergency braking state from the non-emergency braking state.

[0099] S3: When it is determined that the vehicle is in an emergency braking state, the vehicle braking force requirement is calculated based on the current vehicle load and a preset emergency braking average deceleration index.

[0100] In some embodiments of the present invention, step S3 further includes the following steps:

[0101] To calculate the vehicle load, the analog input board sends the collected two analog signals to the main control board through the communication network. The main control board converts them into two vehicle loads. If both vehicle loads are within the effective load range, the larger one is taken as the final vehicle load. If one vehicle load is not within the effective load range, the full load of the vehicle is taken as the final vehicle load.

[0102] S4: Based on the available electric braking force in the current cycle received by the network communication board, the main control board allocates the braking force demand into an electric brake demand and an air brake demand. The main control board then transmits the electric brake demand and the air brake demand to the traction control unit and the brake control unit, respectively, via the network communication board. The traction control unit and the brake control unit then control their corresponding actuators to apply electric braking and air braking to the vehicle, respectively. Simultaneously, the traction control unit transmits the actual applied electric brake force to the main control board via the network communication board.

[0103] In some embodiments of the present invention, a method for allocating an electric braking force demand and an air braking force demand based on a vehicle braking force demand includes the following steps:

[0104] Captures the available electric braking force of the traction system.

[0105] When the available electric braking force is greater than the vehicle braking force demand, the vehicle braking force demand is all allocated as the electric braking force demand.

[0106] When the available electric braking force is less than the vehicle braking force demand, the vehicle braking force demand is distributed into an electric brake demand equal to the available electric braking force and an air brake demand equal to the difference between the vehicle braking force demand and the available electric brake force.

[0107] S5: During the electric braking process, the current speed of the vehicle, the theoretical braking distance of the vehicle from the initial speed to the current speed, and the actual braking distance of the vehicle from the initial speed to the current speed are periodically calculated.

[0108] In some embodiments of the present invention, the method for calculating the current speed of a vehicle includes the following steps:

[0109] The digital input board periodically collects at least four speed pulse signals, and sends the periodically collected four speed pulse signals and corresponding collection times to the main control board through the communication network.

[0110] The main control board calculates at least four axis speeds of the current cycle respectively.

[0111] When the effective axle speeds among at least four axle speeds are not less than two, the average value of the effective axle speeds is taken as the current speed of the vehicle; otherwise, the current vehicle speed is determined to be invalid.

[0112] In some embodiments of the present invention, a method for calculating a theoretical braking distance for a vehicle to be reduced from an initial speed to a current speed includes the following steps:

[0113] Obtain the pre-set average deceleration index a1 of the vehicle emergency braking, and the vehicle emergency braking rate a that meets the signal system requirements. x , the predetermined time threshold t1 at which the application of pure electric-pneumatic combined braking cannot meet the predetermined emergency braking distance requirement, and the predetermined time t2 at which the electric-pneumatic combined braking switches to pure air braking. Among them, the vehicle emergency braking average deceleration index a1 is specifically the average emergency braking deceleration that the traction system and the braking system can achieve for the vehicle respectively; a1, a x , t1 and t2 can be pre-set according to the specific model and hardware configuration of the urban rail vehicle.

[0114] Get the vehicle's initial velocity v1 calculated by the main control board when the emergency brake is triggered.

[0115] Based on the initial speed v1 and the vehicle's guaranteed emergency braking rate a x Calculate the vehicle safety protection braking distance S during emergency braking required by the on-board ATP x :

[0116] S x =v1 2 / (2×a x ).

[0117] Since the worst case is that the actual electro-pneumatic braking applied by the traction system and the braking system is zero within time t1, x -v1×t, then the safe braking distance S x Calculate the average deceleration a that the vehicle needs to achieve by pure air braking y :

[0118] a y =v1 2 / (2×(S x -v1×t)).

[0119] Among them, time t is the sum of t1 and t2, a y Less than a1.

[0120] In the vehicle emergency braking average deceleration index a1 and average deceleration a y The target deceleration a of the electro-pneumatic hybrid brake is selected based on the actual operation of the urban rail vehicle and the performance of the onboard hardware equipment.T It should be noted that a T The larger the value, the more stringent the judgment condition is, and the higher the probability of switching to pure air braking.

[0121] When the electro-pneumatic brake is applied, the vehicle speed gradually decreases, and the current speed v2 of the vehicle is calculated periodically.

[0122] Based on the initial speed v1, current speed v2 and target deceleration a of the electro-pneumatic composite brake T Calculate the theoretical braking distance of the vehicle from its initial speed to its current speed:

[0123] S T =(v1 2 -v2 2 ) / (2×a T ).

[0124] In some embodiments of the present invention, a method for calculating an actual braking distance of a vehicle from an initial speed to a current speed includes the following steps:

[0125] The digital input board sends the periodically collected at least four-way speed pulse signals to the main control board through the communication network, and the main control board calculates the at least four-way shaft speeds of the current cycle respectively.

[0126] The main control board calculates the actual braking distance of the vehicle during this cycle based on at least four speed pulse signals, the number of gears of the on-board speed sensor, and the wheel diameter.

[0127] The actual braking distance of the vehicle from its initial speed to its current speed can be calculated by continuously accumulating the actual braking distance of the vehicle in the current cycle.

[0128] In some embodiments of the present invention, the following steps are included:

[0129] The braking force buildup time t0 is pre-set. The braking force buildup time is the interval from the calculation of the braking force demand to the application of the electro-pneumatic composite brake to the target value after the emergency brake is triggered. It can be pre-set based on the actual operation of the urban rail vehicle and the vehicle hardware performance.

[0130] Since the braking force has not been fully established during this period and cannot be used for braking distance comparison, in this embodiment, after the emergency brake is triggered and the braking force establishment time t0 has passed, the current speed of the vehicle, the theoretical braking distance of the vehicle from the initial speed to the current speed, and the actual braking distance of the vehicle from the initial speed to the current speed are periodically calculated.

[0131] S6: Compare the theoretical braking distance with the actual braking distance in each calculation cycle;

[0132] If the actual braking distance is less than or equal to the theoretical braking distance, it is determined that the cycle is relatively qualified; otherwise, it is determined that the cycle is relatively unqualified;

[0133] S7: The duration of the unqualified cycles is accumulated. If the accumulated duration is consistently less than or equal to a predetermined time threshold t1, the traction system and the braking system are continuously controlled to apply electro-pneumatic combined braking until the vehicle speed drops to a predetermined speed threshold v0. At this point, the electric brake is discontinued, and the braking system is controlled to apply pure air braking to the vehicle until it stops. According to traction characteristics, when the vehicle speed drops to a certain level, for example, below 5 km / h, the available electric braking in the traction system decreases dramatically, affecting vehicle deceleration and the ability to stop the vehicle without rolling away. Therefore, in this embodiment, when the vehicle speed drops to the predetermined speed threshold v0, the main control board gradually reduces the electric braking demand to zero and transmits it to the traction control unit via the network communication board. Simultaneously, a pure air braking command is transmitted to the digital output board via the communication network. The digital output board connects the emergency valve drive command with the vehicle emergency brake command, de-energizing the emergency valve and continuously applying pure air braking until the vehicle stops.

[0134] If the accumulated duration is greater than the predetermined time threshold t1, the electric brake will be stopped immediately, and the main control board will send a pure air brake command to the digital output board through the communication network. The digital output board will control the emergency valve drive command to connect with the vehicle emergency brake command, causing the emergency valve to lose power, thereby continuously applying pure air brake until the vehicle stops.

[0135] In the above exemplary embodiment, the control principle of the emergency brake management device is as follows: Figure 5 The specific working process of the emergency brake management equipment is shown in the attached Figure 6 When emergency braking is triggered, the emergency brake management device first controls the traction control unit and the brake control unit to apply electro-pneumatic braking, and monitors in real time whether the actual braking distance meets the design target. If so, electro-pneumatic braking is continuously applied; otherwise, the emergency valve is controlled to apply pure air braking. During the electro-pneumatic braking process, if the emergency brake management device malfunctions, pure air braking is applied. At low vehicle speeds, due to the rapid decrease in the traction system's electric braking capacity, the emergency brake management device controls the emergency valve to de-energize, applying pure air braking until the vehicle stops. This ensures that the high safety requirements of emergency braking are met, ensuring safe vehicle parking during emergency braking, while also integrating electric braking into the emergency braking control method to minimize wear on the brake caliper and brake disc.

[0136] The control method provided in the above exemplary embodiment is particularly suitable for urban rail vehicles using linear motors, because the electric braking applied by the linear motor is not restricted by wheel-rail adhesion. Under the premise of fully utilizing the electric braking, the air brake can be flexibly controlled under the adhesion restriction, so that the actual deceleration of the vehicle is much greater than the average deceleration index of the vehicle during emergency braking, thereby ensuring safe parking of the vehicle.

[0137] The control method provided in the above exemplary embodiment is also applicable to urban rail vehicles that use electromechanical brakes instead of air brakes. Both the electromechanical brake and traction system rely on motor rotation to output braking force, and both are implemented through electronic control. Unlike air brakes, which rely on the loss of power in the emergency valve to output braking force, a single electromechanical brake device cannot achieve the safety level of a solenoid valve control method. While ensuring a certain level of safety, it is necessary to rely on high-security equipment to manage multiple electromechanical brake devices, converting braking force redundancy into increased safety, thereby achieving the safety level of a solenoid valve control method. Unlike electro-pneumatic hybrid braking, when emergency braking is triggered, the brake support management device first controls the application of electro-electric hybrid braking. If the electro-electric hybrid braking does not meet the braking distance requirements or the vehicle speed is low, it switches to pure electric friction braking.

[0138] Some embodiments of the present invention further provide a braking control system for urban rail vehicles, as shown in the attached Figure 2 As shown, it includes: traction system, braking system and emergency brake management equipment.

[0139] Among them, the traction system is used to apply electric braking to the vehicle, and includes a traction control unit and a traction execution unit.

[0140] The braking system is used to apply air brakes to the vehicle and includes a brake control unit, an emergency valve and a brake actuator unit.

[0141] The emergency brake management device is communicatively connected with the vehicle-mounted load sensor, the vehicle-mounted speed sensor, the brake system, and the traction system respectively.

[0142] The emergency brake management device runs emergency brake management software, and the emergency brake management software includes.

[0143] The emergency braking state judgment module is used to judge whether the vehicle is currently in an emergency braking state based on the collected emergency braking instructions.

[0144] The braking force requirement calculation module is used to calculate the braking force requirement of the vehicle based on the vehicle load.

[0145] The braking force demand distribution module is used to distribute the calculated braking force demand into an electric braking demand and an air braking demand, and send the electric braking demand and the air braking demand to the traction control unit and the brake control unit respectively.

[0146] The periodic calculation module is used to periodically calculate the current speed of the vehicle, the theoretical braking distance of the vehicle from the initial speed to the current speed, and the actual braking distance of the vehicle from the initial speed to the current speed.

[0147] The braking distance comparison module is used to compare the theoretical braking distance with the actual braking distance in each calculation cycle; if the actual braking distance is less than or equal to the theoretical braking distance, the cycle is judged to be qualified; otherwise, the cycle is judged to be unqualified, and the duration of the unqualified cycle is accumulated.

[0148] The brake conversion control module is used to continuously control the traction control unit and the brake control unit to apply electric-pneumatic composite braking when the cumulative duration of the unqualified cycles is less than or equal to the predetermined time threshold until the vehicle speed drops to the predetermined speed threshold, stop applying the electric brake, and control the emergency valve of the brake system to apply pure air braking to the vehicle until it stops; when the cumulative duration is greater than the predetermined time threshold, immediately stop applying the electric brake and control the emergency valve of the brake system to apply pure air braking to the vehicle until it stops.

[0149] In the above exemplary embodiments, as shown in the attached Figure 2 and attached Figure 4 As shown, the emergency brake management device is a two-out-of-two safety computer system that utilizes functional safety and redundancy technologies, ensuring high safety and reliability. The main boards include a power supply board, a main control board, a network communication board, a digital input board, an analog input board, a digital output board, and a backplane. Communication between the boards utilizes a secure protocol, the digital input and output boards utilize dynamic technology, and the main control board employs synchronous voting technology. Together, these three systems achieve "fail-safe" operation and ensure high safety. The two power supply boards are redundant hot backups, and the communication network utilizes a dual-path redundant network, ensuring high reliability.

[0150] In some embodiments of the present invention, the cycle calculation module includes: a vehicle speed calculation unit, a theoretical braking distance calculation unit, and an actual braking distance calculation unit.

[0151] The vehicle speed calculation unit is used to periodically collect at least four speed pulse signals, calculate at least four axle speeds of the current period, and calculate the average value of at least two effective axle speeds as the current speed of the vehicle.

[0152] The theoretical braking distance calculation unit is used to calculate the theoretical braking distance of the vehicle from the initial speed to the current speed based on a preset vehicle emergency braking average deceleration index, the vehicle's guaranteed emergency braking rate, the predetermined time threshold at which the electro-pneumatic composite braking cannot meet the predetermined emergency braking distance requirement, the predetermined time for the electro-pneumatic composite braking to switch to pure air braking, and the calculated current speed of the vehicle.

[0153] The actual braking distance calculation unit is used to take the maximum number of speed pulses corresponding to at least two effective axle speeds in the current cycle as the number of speed pulses in the current cycle, calculate the actual braking distance of the vehicle in this cycle based on the number of speed pulses in the current cycle, the number of gears of the on-board speed sensor and the wheel diameter, and continuously accumulate the actual braking distance of the vehicle in each cycle to obtain the actual braking distance of the vehicle from the initial speed to the current speed.

[0154] In some embodiments of the present invention, the emergency brake management device includes a main control board, a digital input board, an analog input board, a digital output board, and a network communication board connected to the same backplane;

[0155] The digital input board is used to collect emergency braking commands and speed pulse signals sent by the vehicle speed sensor;

[0156] The analog input board is used to collect the load analog signal sent by the vehicle-mounted sensor;

[0157] The digital output board is used to send emergency valve drive instructions to the brake system to control the brake system to apply pure air brakes;

[0158] The network communication board is used to receive available electric braking force information sent by the traction system, and to send air braking requirements to the brake control unit and electric braking requirements to the traction control unit, so as to control the corresponding execution units to apply electric-air composite braking through the traction control unit and the brake control unit;

[0159] The main control board is used to determine whether the vehicle is currently in an emergency braking state, calculate the vehicle's braking force demand, calculate the braking force demand distribution value, calculate the vehicle's current speed, the theoretical braking distance of the vehicle from the initial speed to the current speed, the actual braking distance of the vehicle from the initial speed to the current speed, and control the traction system and braking system to apply electro-pneumatic composite braking or pure air braking based on the comparison results of the theoretical braking distance and the actual braking distance.

[0160] In some embodiments of the present invention, the main control board, digital input board, analog input board, and digital output board all adopt a two-by-two-out-of-two architecture design, and perform hardware two-out-of-two voting when collecting signals or outputting instructions.

[0161] The structure of the digital input board is shown in the attached Figure 7 As shown, attached Figure 7A and B are the two channels of a two-out-of-two system. The digital input board uses a dynamic circuit to acquire external hard-wired signals. Its operating principle is as follows: The CPU periodically sends dynamic pulse signals to the acquisition circuit. When the hard-wired signal is high, the CPU receives the same pulse signal. When the hard-wired signal is low, the CPU receives a high-level signal. If the acquisition circuit fails, the CPU also receives a high-level signal, achieving fault-driven safety.

[0162] The structure of the digital output board is shown in the attached Figure 8 As shown, attached Figure 8 A and B represent the two channels of the two-out-of-two system. The digital output board uses a dynamic output circuit to output hard-wired signals. Its operating principle is as follows: when the CPU sends a dynamic pulse signal to the driver circuit, the driver circuit outputs a high level; when the CPU does not send a pulse signal to the driver circuit or the output circuit fails, the driver circuit outputs a low level. The output voltage of channel A is connected to channel B, which controls the output of channel B, implementing a hardware two-out-of-two voting function and achieving fault-driven safety.

[0163] The structure of the main control board is shown in the attached Figure 9 As shown, attached Figure 9 In the figure, A and B represent the two channels of a two-out-of-two system. Each channel contains two CPUs: CPU1 performs logical calculations, and CPU2 performs synchronous voting. CPU2 periodically receives data from the input board and sends it to CPU1 via a dual-port RAM. CPU2 obtains CPU1's calculation results from the dual-port RAM, exchanges data with CPU2 on the other channel via Ethernet, performs a two-out-of-two vote, and finally sends the voting results to the output board.

[0164] In the above exemplary embodiment, by designing the main control board, digital input board, analog input board and digital output board into a two-by-two-take-two architecture, the safety of the emergency braking management equipment is effectively improved, thereby enabling electric braking to be applied to emergency braking conditions.

[0165] In some embodiments of the present invention, a fault handling module is further included, which is used to detect its own working status in real time when the emergency braking management device determines that the vehicle is in an emergency braking state. When it is determined that a fault occurs, the traction system is controlled to immediately stop applying electric braking, and the emergency valve of the braking system is controlled to apply pure air braking to the vehicle until it stops.

[0166] Specifically, when one of the following fault situations occurs: the main control board determines that it has a fault itself, the main control board determines that the vehicle speed calculation has a fault, the main control board determines that the communication between the main control board and the digital acquisition board or the network communication board has a fault, or the network communication board determines that the communication between the main control board and the traction control unit or the braking control unit has a fault, the main control board sends a control fault information to the digital output board, and the digital output board controls the emergency valve drive command to be connected with the vehicle emergency braking command.

[0167] When one of the following fault situations occurs: the digital output board determines that it has a fault itself, or that the digital output board determines that the communication between it and the main control board has a fault, the digital output board controls the emergency valve drive command to be connected with the vehicle emergency brake command.

[0168] When one of the failure situations occurs, such as a complete failure of the digital output board, a complete failure of the brake security management device, or a power outage, the digital output board automatically directs the emergency valve drive command to be connected with the vehicle emergency brake command.

[0169] It should be noted that the results of the above fault handling are that when the emergency brake is triggered, the vehicle emergency brake command loses power. Since the emergency valve drive command is connected to the vehicle emergency brake command, the emergency valve drive command also loses power, thereby controlling the emergency valve to directly apply pure air braking.

[0170] In some embodiments of the present invention, the method for converting the braking mode is specifically as follows:

[0171] If the main control board determines that the vehicle is in a non-emergency braking state, it sends a non-emergency braking command to the digital output board through the communication network. The digital output board controls the emergency valve drive command to connect with the emergency braking command, thereby energizing the emergency valve;

[0172] If the main control board determines that the vehicle enters the emergency braking state from the non-emergency braking state, it sends an electric-pneumatic composite braking command to the digital output board through the communication network. The digital output board controls the emergency valve drive command and connects it to the vehicle power supply, thereby energizing the emergency valve.

[0173] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0174] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to preferred embodiments, persons skilled in the art should understand that the specific implementation methods of the present invention may still be modified or some technical features may be replaced by equivalents without departing from the spirit of the technical solutions of the present invention, and all of these should fall within the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A braking control method for urban rail vehicles, characterized in that: The urban rail vehicle includes a traction system and a braking system, which are respectively used to apply electric braking and air braking. The control method includes the following steps: Determine whether the current vehicle is in an emergency braking state; When the vehicle is judged to be in an emergency braking state, the vehicle braking force requirement is calculated based on the vehicle's current load; Allocating electric braking demand and air braking demand based on the vehicle braking force demand, thereby controlling the traction system and the braking system to apply electric-air composite braking to the vehicle; During the application of electro-pneumatic brakes, the current speed of the vehicle, the theoretical braking distance required for the vehicle to be decelerated from the initial speed to the current speed, and the actual braking distance required for the vehicle to be decelerated from the initial speed to the current speed are periodically calculated; In each calculation cycle, the theoretical braking distance is compared with the actual braking distance; If the actual braking distance is less than or equal to the theoretical braking distance, it is determined that the current cycle is relatively qualified; otherwise, it is determined that the current cycle is relatively unqualified; The duration of the unqualified cycles is accumulated. If the accumulated duration is always less than or equal to the predetermined time threshold, , the electro-pneumatic brake is continuously applied until the vehicle speed drops to a predetermined speed threshold. , stop applying the electric brake, and control the brake system to apply pure air brake to the vehicle until the vehicle stops; If the accumulated duration is greater than the preset time threshold , the electric brake is immediately stopped, and the brake system is controlled to apply pure air brake to the vehicle until the vehicle stops.

2. The urban rail vehicle braking control method according to claim 1, characterized in that: The method for calculating the current speed of a vehicle comprises the following steps: Periodically collecting at least four speed pulse signals and respectively calculating at least four shaft speeds of the current period; When the effective axle speeds among the at least four axle speeds are not less than two, an average value of the effective axle speeds is taken as the current speed of the vehicle.

3. The urban rail vehicle braking control method according to claim 1, characterized in that: The method for calculating the theoretical braking distance of a vehicle from an initial speed to a current speed comprises the following steps: Get the preset average deceleration index of the vehicle emergency braking , Vehicle ensures emergency braking rate , the predetermined time threshold at which the electro-pneumatic hybrid brake fails to meet the predetermined emergency braking distance requirement , the scheduled time for the electro-pneumatic brake to switch to pure air brake ; Calculate the initial velocity of the vehicle when the emergency brake is triggered ; Based on the initial velocity and the vehicle ensures an emergency braking rate Calculate the initial speed of the vehicle during emergency braking Safety braking distance to parking : ； Based on the safety protection braking distance Calculate the average deceleration that the vehicle must achieve using pure air braking : ； Among them, time The predetermined time threshold and the scheduled time of and; Average deceleration index during vehicle emergency braking and the average deceleration Select the target deceleration of the electro-pneumatic brake ; Calculate the vehicle's current speed ; Based on the initial velocity , current speed Target deceleration of electro-pneumatic brake Calculate the vehicle's initial velocity Reduce to current speed Theoretical braking distance: 。 4. The urban rail vehicle braking control method according to claim 1, characterized in that: The method for calculating the actual braking distance of a vehicle from an initial speed to a current speed comprises the following steps: Periodically collecting at least four speed pulse signals and respectively calculating at least four shaft speeds of the current period; When the effective shaft speeds among the at least four shaft speeds are not less than two, the maximum number of speed pulses corresponding to the effective shaft speeds is taken as the number of speed pulses in the current cycle; Calculating an actual braking distance of the vehicle in the current cycle based on the number of speed pulses in the current cycle, the number of gears of the onboard speed sensor, and the wheel diameter; The actual braking distance of the vehicle in each cycle is continuously accumulated to obtain the actual braking distance of the vehicle from the initial speed to the current speed.

5. The urban rail vehicle braking control method according to any one of claims 1 to 4, characterized in that: The following steps are involved: Preset braking force build-up time ; Emergency braking is triggered and the braking force build-up time has passed After that, the current speed of the vehicle, the theoretical braking distance of the vehicle from the initial speed to the current speed, and the actual braking distance of the vehicle from the initial speed to the current speed are periodically calculated.

6. The urban rail vehicle braking control method according to claim 1, characterized in that: The method for allocating electric brake demand and air brake demand based on the vehicle braking force demand comprises the following steps: obtaining an available electric braking force of the traction system; When the available electric braking force is greater than the vehicle braking force requirement, allocating the vehicle braking force requirement as the electric braking force requirement; When the available electric braking force is less than the vehicle braking force request, the vehicle braking force request is distributed into an electric brake request equal to the available electric braking force and an air brake request equal to the difference between the vehicle braking force request and the available electric brake force.

7. A braking control system for urban rail vehicles, characterized in that: A method for controlling braking of an urban rail vehicle according to any one of claims 1 to 6, comprising: a traction system, a braking system, and an emergency braking management device; The traction system is used to apply electric braking to the vehicle and includes a traction control unit; The braking system is used to apply air brakes to the vehicle and includes a brake control unit and an emergency valve; The emergency brake management device is connected to the vehicle load sensor, the vehicle speed sensor, and the emergency valve through hard wires, and is communicatively connected to the traction control unit and the brake control unit through the train network; The emergency brake management device runs emergency brake management software, which includes: An emergency braking state judgment module is used to judge whether the vehicle is currently in an emergency braking state based on the collected emergency braking instructions; A braking force demand calculation module, used to calculate the braking force demand of the vehicle based on the vehicle load; a braking force demand allocation module, configured to allocate the calculated braking force demand into an electric braking demand and an air braking demand, and send the electric braking demand and the air braking demand to the traction control unit and the brake control unit, respectively, so that the traction control unit and the brake control unit control corresponding execution units to apply electric-air composite braking; a periodic calculation module, for periodically calculating the current speed of the vehicle, a theoretical braking distance of the vehicle from an initial speed to the current speed, and an actual braking distance of the vehicle from an initial speed to the current speed; A braking distance comparison module is configured to compare the theoretical braking distance with the actual braking distance in each calculation cycle; if the actual braking distance is less than or equal to the theoretical braking distance, the cycle is determined to be qualified; otherwise, the cycle is determined to be unqualified, and the duration of the unqualified cycle is accumulated; The brake conversion control module is used to continuously control the traction control unit and the brake control unit to apply electric-pneumatic composite braking until the vehicle speed drops to a predetermined speed threshold when the cumulative duration of the relatively unqualified cycles is less than or equal to a predetermined time threshold, stop applying the electric brake, and control the emergency valve to apply pure air braking to the vehicle until it stops; when the cumulative duration of the relatively unqualified cycles is greater than the predetermined time threshold, immediately control the traction control unit to stop applying the electric brake and control the emergency valve to apply pure air braking to the vehicle until it stops.

8. The urban rail vehicle braking control system according to claim 7, characterized in that: The emergency brake management device includes a main control board, a digital input board, an analog input board, a digital output board and a network communication board connected to the same backplane; The digital input board is used to collect emergency braking instructions and speed pulse signals sent by the vehicle speed sensor; The analog input board is used to collect load analog signals sent by vehicle-mounted sensors; The digital output board is used to send an emergency valve drive instruction to the brake system to control the brake system to apply pure air braking; The network communication board is used to receive available electric braking force information sent by the traction system, and to send an air braking request to the brake control unit and an electric braking request to the traction control unit, so as to control the corresponding execution units to apply electric-air composite braking through the traction control unit and the brake control unit; The main control board is used to determine whether the vehicle is currently in an emergency braking state, calculate the vehicle's braking force demand, calculate the braking force demand distribution value, calculate the vehicle's current speed, the theoretical braking distance of the vehicle from an initial speed to the current speed, and the actual braking distance of the vehicle from the initial speed to the current speed, and control the traction system and the braking system to apply electro-pneumatic composite braking or pure air braking based on the comparison result of the theoretical braking distance and the actual braking distance.

9. The urban rail vehicle braking control system according to claim 8, characterized in that: The main control board, the digital input board, the analog input board and the digital output board all adopt a two-by-two-take-two architecture design, and perform hardware two-by-two voting when collecting signals or outputting instructions.

10. The urban rail vehicle braking control system according to claim 7, characterized in that: It further includes a fault handling module, which is used to detect its own working status in real time when the emergency braking management device determines that the vehicle is in an emergency braking state, and immediately stop applying electric braking when it determines that a fault occurs, and control the emergency valve of the braking system to apply pure air braking to the vehicle until it stops.

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