Urban rail vehicle braking control method and system

Abstract

The invention relates to an urban rail vehicle braking control method and system, and the method comprises the following steps: when a vehicle triggers emergency braking, calculating a braking force demand, and applying electro-pneumatic composite braking to the vehicle based on the braking force demand; in the applying process, the current speed, the theoretical braking distance and the actual braking distance of the vehicle are periodically calculated; the theoretical braking distance and the actual braking distance are compared in each calculation period; and continuously applying electro-pneumatic composite braking until the vehicle speed is reduced to a preset speed threshold value based on the comparison result, and controlling a braking system to apply pure air braking to the vehicle until the vehicle stops, or immediately stopping applying electric braking based on the comparison result, and controlling the braking system to apply pure air braking to the vehicle until the vehicle stops. Electric braking is introduced into emergency braking, closed-loop management is carried out on the actual braking effect of electric-pneumatic composite braking, on the basis that safe parking of the vehicle is guaranteed, abrasion of a brake disc and a brake clamp is reduced to the maximum extent, and therefore the maintenance and repair cost of the vehicle is effectively reduced.

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 braking function of the vehicle. The traction system and the braking system provide two braking modes: electric braking and air braking.

[0003] At present, electronic control is usually used in the normal braking and rapid braking of vehicles. The braking system is responsible for calculating and allocating the braking force requirements, and based on the available electric braking force fed back by the traction system, the required braking force is allocated to the traction system first. The insufficient part is supplemented by air braking.

[0004] For emergency braking, its safety level is much higher than that of normal braking and rapid braking, and it is the last guarantee for safe parking of vehicles. At present, emergency braking is usually implemented by electromagnetic valve control, and the emergency valve of the braking system is de-energized by the vehicle emergency brake hard line to apply pure air braking. Although this pure air braking method can ensure that the vehicle stops quickly in an emergency, the sudden application of pure air braking when the train is running at high speed will cause the wear of the brake caliper and brake disc to increase. In the long run, excessive wear of the brake caliper and brake disc will increase the maintenance and repair costs of the vehicle and reduce the operating efficiency and service life of the vehicle.

[0005] Therefore, there is an urgent need for a brake control method that can improve the safety of the electronic control mode 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 to 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 is ensured 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 a city rail vehicle, the city rail vehicle comprises a traction system and a braking system, which are used to apply electric braking and air braking respectively, and the control method comprises the following steps:

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

[0010] When it is determined that the vehicle is in an emergency braking state, the vehicle braking force requirement is calculated based on the current load of the vehicle;

[0011] Based on the vehicle braking force demand, the electric braking demand and the air braking demand are distributed, and then the traction system and the braking system are controlled to apply electric-air composite braking to the vehicle;

[0012] During the application of the electric-pneumatic composite brake, 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;

[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, and then the electric braking is stopped, and the braking system is controlled to apply pure air braking to the vehicle until it stops.

[0016] If the accumulated time is greater than the predetermined time threshold t1, the electric brake is stopped immediately, and the brake system is controlled to apply pure air brakes 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 comprises 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 shaft speeds among at least four shaft speeds are not less than two shaft speeds, the average value of the effective shaft speeds is taken as the current speed of the vehicle.

[0020] In some embodiments of the present invention, the method for calculating the theoretical braking distance of a vehicle from an initial speed to a current speed comprises 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 electric-pneumatic composite brake cannot meet the predetermined emergency braking distance requirement, and a predetermined time t2 at which the electric-pneumatic composite brake switches to pure air brake;

[0022] Calculate the initial speed v1 of the vehicle when the emergency brake 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 the electric brake T ;

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

[0030] Based on the initial speed v1, current speed 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, the method for calculating the actual braking distance of a vehicle from an initial speed to a current speed comprises 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 among at least four shaft speeds is not less than two, 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 on-board 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 build-up 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.

[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] Obtaining 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 as 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, including a brake control unit and an emergency valve;

[0048] The emergency brake management device is connected to the vehicle load sensor, the vehicle speed sensor, and the 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;

[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 for calculating the braking force demand of the vehicle based on the vehicle load;

[0052] A braking force demand allocation module is used 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 as to control the corresponding execution units to apply electric-air composite braking through the traction control unit and the brake control unit;

[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, it is determined that the current cycle is relatively qualified; otherwise, it is determined that the current cycle is relatively 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 relatively 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 to apply 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 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, for calculating at least four shaft speeds of a current period based on periodic collection of at least four speed pulse signals, and calculating an average value of at least two effective shaft speeds as the current speed of the vehicle;

[0058] a theoretical braking distance calculation unit, for calculating the theoretical braking distance of the vehicle from the initial speed to the current speed based on a preset average deceleration index of the vehicle in emergency braking, a guaranteed emergency braking rate of the vehicle, a predetermined time threshold at which the electric-pneumatic composite braking cannot meet the predetermined emergency braking distance requirement, a predetermined time for the electric-pneumatic composite braking to switch to pure air braking, and a 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 the effective shaft speeds as the number of speed pulses in the current cycle based on at least two effective shaft speeds 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 when the initial speed is reduced to the current speed.

[0060] In some embodiments of the present invention, the emergency brake management device includes a main control board, a digital quantity input board, an analog quantity input board, a digital quantity 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 load analog signals sent by vehicle-mounted sensors;

[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 the available electric braking force information sent by the traction system, and to send an air braking demand to the brake control unit and an electric braking demand to the traction control unit, so as to control the corresponding execution unit to apply electric-air compound 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 electric-pneumatic composite braking or pure air braking based on the comparison result 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 is determined 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 introduces electric braking into the control process of emergency braking. When the vehicle is in emergency braking, the traction brake unit and the brake control unit are used to control the corresponding actuator to apply electric-pneumatic composite braking. During the application of electric-pneumatic composite braking, the actual braking effect is managed in a closed loop. The braking strategy is adjusted based on the actual braking effect. Compared with the emergency braking method of directly controlling the emergency valve to implement pure air braking in the prior art, the wear of the brake disc and the brake caliper is minimized on the basis of ensuring the safe parking of the vehicle, thereby effectively reducing the maintenance and repair cost of the vehicle.

[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 in conjunction with the accompanying drawings. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0072] Figure 1 A flow chart of a braking control method for an urban rail vehicle;

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

[0076] Figure 5 A control schematic diagram of an 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 the embodiment of the present application;

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

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

[0080] Fig. 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 the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present 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 of their variations 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 of the embodiments 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 Fig. 9 As shown, in an illustrative embodiment of a braking control method for a rail vehicle of the present invention, the rail vehicle comprises a traction system and a braking system, which are used to apply electric braking and air braking respectively. The braking control method comprises 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, the vehicle speed sensor, and the 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 quantity input board, an analog quantity input board, a digital quantity output board and a network communication board connected to the same backplane.

[0089] Among them, the digital input board is used to collect emergency braking instructions and speed pulse signals sent by the on-board speed sensor. The analog input board is used to collect load analog signals sent by the on-board sensor. The digital output board is used to send emergency valve drive instructions to the braking system to control the braking system to apply pure air braking. The network communication board is used to send electric braking requirements and air braking requirements to the traction system and the braking system respectively to control the traction system and the braking system to apply electric-air composite braking, and receive the available electric braking force information fed back by the traction system; the main control board is used for data processing and calculation.

[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 that the emergency brake management device controls the traction control unit of the traction system and the brake control unit of the brake system to apply electric-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 emergency brake management device has high safety, 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 application link of the secondary emergency brake is that the emergency brake management device controls the emergency valve of the brake system to apply pure air brake. The application link of the secondary emergency brake depends on the emergency valve of the brake system. The emergency valve has high reliability. The high-safety emergency brake management device and the high-reliability emergency valve cooperate to achieve high-safety secondary emergency brake, which can ensure 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 the current vehicle is in an emergency braking state includes:

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

[0097] When the digital input board detects that the emergency braking command is at a high level, 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 a high level to a low level, the main control board determines that the vehicle enters an emergency braking state from a 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 load of the vehicle 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, and 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: The main control board allocates the braking force demand into electric braking demand and air braking demand based on the available electric braking force of the current cycle received by the network communication board, and sends the electric braking demand and air braking demand to the traction control unit and the brake control unit through the network communication board, so that the traction control unit and the brake control unit control the corresponding execution units to apply electric braking and air braking to the vehicle respectively. At the same time, the traction control unit sends the actual applied electric braking force to the main control board through the network communication board.

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

[0104] Access 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 process of applying the electric brake, 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 comprises the following steps:

[0109] The digital quantity input board periodically collects at least four speed pulse signals, and sends the periodically collected four speed pulse signals and the corresponding collection time 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 shaft speeds among at least four shaft speeds are not less than two shaft speeds, the average value of the effective shaft 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, the method for calculating the theoretical braking distance of a vehicle from an initial speed to a current speed comprises the following steps:

[0113] Obtain the preset average deceleration index a1 of the vehicle emergency braking, and the vehicle emergency braking rate a that meets the requirements of the signal system x , the predetermined time threshold t1 at which the pure electric-pneumatic brake cannot meet the predetermined emergency braking distance requirement, and the predetermined time t2 at which the electric-pneumatic brake switches to the pure air brake. 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 all be pre-set according to the specific model and hardware configuration of the urban rail vehicle.

[0114] Get the initial speed v1 of the vehicle 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 electric-pneumatic composite braking actually applied by the traction system and the braking system is zero during 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 Smaller than a1.

[0120] In the vehicle emergency braking average deceleration index a1 and average deceleration a y The target deceleration a of the electric-pneumatic hybrid brake is selected based on the actual operation of the urban rail vehicle and the performance of the on-board 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 is gradually reduced, 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 brake T Calculate the theoretical braking distance of the vehicle from the initial speed to the current speed:

[0123] S T =(v1 2 -v2 2 ) / (2×a T ).

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

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

[0126] The main control board calculates the actual braking distance of the vehicle in 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 the initial speed to the 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 build-up time t0 is preset. The braking force build-up time is the interval time from the calculation of the braking force demand to the application of the electric-pneumatic composite brake to the target value after the emergency brake is triggered. It can be preset according to 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 braking 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: Accumulate the duration of the unqualified cycles. If the accumulated duration is always less than or equal to the predetermined time threshold t1, the traction system and the brake system are continuously controlled to apply electric-pneumatic composite braking until the vehicle speed drops to the predetermined speed threshold v0, stop applying electric braking, and control the brake system to apply pure air braking to the vehicle until it stops. According to the traction characteristics, when the vehicle speed drops to a certain level, for example, when it drops to below 5km / h, the available electric braking of the traction system is sharply reduced, affecting the vehicle's deceleration and stopping without slipping. 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, sends it to the traction control unit through the network communication board, and sends the pure air braking command to the digital output board through the communication network. The digital output board controls the emergency valve drive command to be connected with the vehicle emergency braking command, so that the emergency valve loses power, thereby continuously applying pure air braking until the vehicle stops.

[0134] If the accumulated duration is greater than the preset 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 brakes 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 As shown. When emergency braking is triggered, the emergency brake management device first controls the traction control unit and the brake control unit to apply electric-pneumatic composite braking, and monitors in real time whether the current actual braking distance meets the design target. If it does, the electric-pneumatic composite braking is continuously applied, otherwise the emergency valve is controlled to apply pure air braking; during the application of electric-pneumatic composite braking, if the emergency brake management device fails, pure air braking is applied; when the vehicle speed is low, due to the rapid decrease in the electric braking capacity of the traction system, the emergency brake management device controls the emergency valve to lose power and applies pure air braking until the vehicle stops, ensuring that the high safety requirements of emergency braking are met and the vehicle stops safely during emergency braking, while introducing electric braking into the braking control method of emergency braking, minimizing the wear of 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 emergency braking, thereby ensuring the safe parking of the vehicle.

[0137] The control method provided by the above-mentioned exemplary embodiment is also applicable to urban rail vehicles that use electronic mechanical brakes instead of air brakes. Both the electronic mechanical brake and the traction system rely on the rotation of the motor to output the braking force, and are both implemented through electronic control. Different from the logic of air brakes that rely on the emergency valve to lose power to output the braking force, a single set of electronic mechanical brake devices is difficult to achieve the safety level of the solenoid valve control method. It is necessary to rely on high-security level equipment to manage multiple sets of electronic mechanical brake devices on the basis of ensuring that they achieve a certain level of safety, and convert the redundancy of the braking force capacity into an improvement in safety, thereby achieving the safety level of the solenoid valve control method. Unlike the electric-pneumatic composite brake, when the emergency brake is triggered, the brake guarantee management device first controls the application of the electric-electric composite brake, and switches to pure electric friction braking when the electric-electric composite brake does not meet the braking distance requirements or the vehicle speed is low.

[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] 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 brake 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 load sensor, the vehicle 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 allocation module is used 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.

[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, it is determined that the current cycle is relatively qualified; otherwise, it is determined that the current cycle is relatively 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 in the figure, the emergency brake management equipment is a two-out-of-two safety computer system, which adopts functional safety technology and redundancy technology and has high safety and reliability. The boards mainly include power board, main control board, network communication board, digital input board, analog input board, digital output board and backplane. The communication between the boards adopts a safety protocol, the digital input board and the digital output board adopt dynamic technology, and the main control board adopts synchronous voting technology. The three together realize "fail-safety" and ensure the high safety of the equipment. The two power boards are redundant hot backups, and the communication network adopts a dual-channel redundant network. The two together ensure the high reliability of the equipment.

[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 calculate at least four axle speeds of the current period based on periodic collection of at least four speed pulse signals, 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, a vehicle guaranteed emergency braking rate, a predetermined time threshold at which the electro-pneumatic composite braking cannot meet the 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.

[0153] The actual braking distance calculation unit is used to take the maximum number of speed pulses corresponding to the effective axle speeds as the number of speed pulses in the current cycle based on at least two effective axle speeds 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 quantity input board, an analog quantity input board, a digital quantity 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 load analog signals sent by vehicle-mounted sensors;

[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 the available electric braking force information sent by the traction system, and to send an air braking demand to the brake control unit and an electric braking demand to the traction control unit, so as to control the corresponding execution unit to apply electric-air compound 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 electric-pneumatic composite braking or pure air braking based on the comparison result 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. Figure 7 As shown, attached Figure 7A and B are two channels of the two-out-of-two system. The digital input board uses a dynamic circuit to collect external hard-wired signals. Its working principle is as follows: the CPU periodically sends a dynamic pulse signal to the acquisition circuit. When the hard-wired signal is high, the CPU also receives the same pulse signal. When the hard-wired signal is low, the CPU receives a high-level signal. When the acquisition circuit fails, the CPU also receives a high-level signal to achieve fault-oriented safety.

[0162] The structure of the digital output board is shown in the attached figure. Figure 8 As shown, attached Figure 8 A and B are two channels of the two-out-of-two system. The digital output board uses a dynamic output circuit to output hard-line signals. Its working principle is as follows: when the CPU sends a dynamic pulse signal to the drive circuit, the drive circuit outputs a high level; when the CPU does not send a pulse signal to the drive circuit or the output circuit fails, the drive circuit outputs a low level. The output voltage of channel A is connected to channel B to control the output of channel B, realizing the hardware two-out-of-two voting function and achieving fault-oriented safety.

[0163] The structure of the main control board is as shown in the attached Fig. 9 As shown, attached Fig. 9 A and B are two channels of the two-out-of-two system. Each channel contains two CPUs, CPU1 is responsible for performing logical calculations, and CPU2 is responsible for performing synchronous voting. CPU2 periodically receives data sent by the input board and sends it to CPU1 through the dual-port RAM. CPU2 obtains the calculation results of CPU1 through the dual-port RAM, and exchanges data with another channel CPU2 through Ethernet to perform two-out-of-two voting, 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 as a two-by-two-out-of-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, 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 quantity 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 control fault information to the digital quantity output board, and the digital quantity 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 with the main control board fails, 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 protection management device, or a power failure, the digital output board automatically directs the emergency valve drive command to connect 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 solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A braking control method for urban rail vehicles, characterized in that: The urban rail vehicle comprises a traction system and a braking system, which are used to apply electric braking and air braking respectively. The control method comprises the following steps: Determine whether the current vehicle is in an emergency braking state; When it is determined that the vehicle is in an emergency braking state, the vehicle braking force requirement is calculated based on the current load of the vehicle; 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 the electric-pneumatic composite brake, 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; 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 t1, the electric-pneumatic composite brake is continuously applied until the vehicle speed drops to the predetermined speed threshold v0, and the electric brake is stopped, and the brake system is controlled to apply pure air brake to the vehicle until the vehicle stops. 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 brakes 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 the 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 shaft speeds among the at least four shaft speeds are not less than two shaft speeds, an average value of the effective shaft 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: 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 electric-pneumatic composite brake cannot meet the predetermined emergency braking distance requirement, and a predetermined time t2 at which the electric-pneumatic composite brake switches to pure air brake; Calculate the initial speed v1 of the vehicle when the emergency brake is triggered; Based on the initial speed v1 and the vehicle's guaranteed emergency braking rate a x Calculate the safety protection braking distance S from the initial speed v1 to the parking of the vehicle during emergency braking x : S x =v1 2 / (2×a x ); 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 : a y =v1 2 / (2×(S x -v1×t)); Wherein, time t is the sum of the predetermined time threshold t1 and the predetermined time t2; In the vehicle emergency braking average deceleration index a1 and the average deceleration a y Select the target deceleration a of the electric-pneumatic composite brake T ; Calculate the vehicle's current speed v2; Based on the initial speed v1, the current speed v2 and the target deceleration a of the electro-pneumatic composite brake T Calculate the theoretical braking distance of the vehicle from the initial speed v1 to the current speed v2: S T =(v1 2 -v2 2 ) / (2×a T )。 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. 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; 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 the braking force build-up time t0; After the emergency brake is triggered and the braking force build-up 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.

6. The urban rail vehicle braking control method according to claim 1, characterized in that: The method for allocating the electric braking force demand and the air braking force demand based on the vehicle braking force demand comprises the following steps: obtaining 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 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.

7. The urban rail vehicle braking control system according to claim 1, characterized in that: include: traction systems, braking systems and emergency brake management equipment; The traction system is used to apply electric braking to the vehicle, and includes a traction control unit; The brake 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 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, and the emergency brake management software 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 for calculating the braking force demand of the vehicle based on the vehicle load; a braking force demand allocation module, used for allocating the calculated braking force demand into an electric braking demand and an air braking demand, and sending the electric braking demand and the air braking demand to the traction control unit and the brake control unit respectively, so as to control the corresponding execution units to apply electric-air compound braking through the traction control unit and the brake control unit; A periodic calculation module, used for periodically calculating 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; A 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, it is determined that the current cycle is relatively qualified; otherwise, it is determined that the current cycle is relatively 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 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 electric braking, and control the emergency valve to apply pure air braking to the vehicle until it stops; when the cumulative duration of the unqualified cycles is greater than the predetermined time threshold, immediately control the traction control unit to stop applying electric braking, 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 quantity input board, an analog quantity input board, a digital quantity output board and a network communication board connected to the same backplane; The digital quantity input board is used to collect the emergency braking command and the speed pulse signal 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 air braking requirements to the brake control unit and electric braking requirements to the traction control unit, so as to control the corresponding execution unit to apply electric-air compound braking through the traction control unit and the brake control unit; The main control panel 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, the actual braking distance of the vehicle from an initial speed to the current speed, and control the traction system and the braking system to apply electric-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-out-of-two architecture design, and perform hardware two-out-of-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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