Low-floor tramcar hydraulic braking system and control method thereof

Abstract

The invention relates to a hydraulic braking system of a low-floor tramcar and a control method of the hydraulic braking system, and belongs to the technical field of braking control. The hydraulic braking system comprises an electronic braking control unit, a hydraulic unit, a braking clamp, a braking disc and a temperature sensor installed on the braking disc; the electronic braking control unit receives the electric braking effective signal and the required hydraulic braking force, and calculates the initial distribution coefficient of the hydraulic braking force on each bogie; acquiring the temperature of the brake disc through a temperature sensor; when the vehicle is in a non-braking working condition, calculating a speed limit value according to the initial distribution coefficient and the temperature of the brake disc; when the vehicle is in the braking working condition, the hydraulic braking force on the bogie is distributed according to the initial distribution coefficient; and when the temperature of the brake disc is larger than or equal to the first threshold value and smaller than the preset maximum allowable temperature, the hydraulic braking force on the bogie is redistributed, control can be conducted according to the actual heat state of the brake disc instead of a fixed theoretical value, and the beneficial effect that the running adaptability and energy efficiency of the vehicle are improved on the premise that braking safety is guaranteed is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of brake control, in particular to a low-floor tram hydraulic brake system and a control method thereof. BACKGROUND

[0002] In order to realize 100% low-floor structure, the space of the vehicle bottom of the low-floor tram is extremely limited, which leads to small size of the brake disc and brake caliper of the hydraulic brake system and limited heat capacity of the system. Especially when the electric brake fails, the hydraulic brake system needs to bear all the braking energy independently, which is easy to cause heat recession due to sharp rise of the brake disc temperature, leading to decline of the braking force and serious threat to the driving safety.

[0003] At present, the existing technology generally adopts a speed limit operation strategy based on theoretical heat capacity calculation. A fixed speed limit level is calculated in advance according to specific environmental temperature, fixed line condition, rated vehicle load and brake equipment parameters, and the vehicle is speed limited according to the fixed speed limit level when the electric brake fails.

[0004] However, in actual operation of the low-floor tram, the line condition, environmental temperature and vehicle load are in dynamic change, and in some cities, the low-floor tram does not enjoy independent road right, and the road condition is more complex. The fixed theoretical speed limit value cannot truly reflect the real-time heat capacity of the system, leading to too conservative speed limit and seriously restricting the operation efficiency of the vehicle. In addition, under complex road conditions, the fixed speed limit level may still cause the brake disc temperature to accumulate and exceed the permitted range due to frequent braking, causing heat recession phenomenon and significant safety risk. SUMMARY

[0005] In view of the deficiencies in the related art, the present application aims to provide a low-floor tram hydraulic brake system and method to solve the technical problem that the fixed speed limit strategy of the prior art cannot adapt to the actual dynamic change of the operation condition, leading to low vehicle operation efficiency and safety risk of brake heat recession under complex road conditions.

[0006] The present application provides a low-floor tram hydraulic brake system, comprising: an electronic brake control unit, which is communicatively connected to a vehicle control unit; a hydraulic unit, which is electrically connected to the electronic brake control unit and is used for outputting hydraulic pressure or releasing hydraulic pressure according to a control instruction sent by the electronic brake control unit; a brake caliper, which is installed on a bogie and is connected to the hydraulic unit in a pipeline manner, and is used for receiving the hydraulic pressure in a braking condition and converting the hydraulic pressure into positive pressure; A brake disc is installed on a rotating shaft and rotates with the rotating shaft, and the brake disc is located in the clamping range of the brake caliper for friction braking by bearing the normal pressure in the braking condition; A temperature sensor is installed on the brake disc for acquiring the brake disc temperature; The electronic brake control unit is configured to: receive the electric brake effective signal and the required hydraulic braking force sent by the vehicle control unit, and calculate the initial distribution coefficient of the hydraulic braking force on each bogie; acquire the brake disc temperature through the temperature sensor; When the vehicle is in a non-braking condition, a speed limit value is calculated according to the initial distribution coefficient and the brake disc temperature, and the speed limit value is sent to the vehicle control unit to control the vehicle to run at a limited speed; When the vehicle is in a braking condition, the hydraulic braking force on the bogie is distributed according to the initial distribution coefficient, and the hydraulic pressure required for braking is calculated according to the hydraulic braking force, so as to perform friction braking on the vehicle; When the brake disc temperature is greater than or equal to a first threshold value and less than a preset maximum allowable temperature, the distribution coefficient of the hydraulic braking force on each bogie is recalculated, and the hydraulic braking force on the bogie is redistributed.

[0007] By introducing a temperature sensor and configuring an electronic brake control unit to acquire the brake disc temperature in real time, speed limit calculation and braking force dynamic distribution are respectively performed in different conditions, so that the system can be controlled according to the actual thermal state of the brake disc rather than a fixed theoretical value, thereby improving the operating efficiency in a non-braking condition by real-time speed limiting, and effectively suppressing the brake disc temperature rise in a braking condition by dynamically adjusting the braking force distribution, avoiding the occurrence of thermal recession, and overall realizing the beneficial effects of improving the adaptability and energy efficiency of the vehicle under the premise of ensuring braking safety.

[0008] In some embodiments of the application, the electronic brake unit is further configured to: determine whether a brake request sent by the vehicle control unit is received; If the brake request sent by the vehicle control unit is not received, the vehicle is in a non-braking condition; If the brake request sent by the vehicle control unit is received, the vehicle is in a braking condition.

[0009] By judging whether a braking request is received to accurately distinguish the working condition of the vehicle, the electronic brake control unit can switch the control mode according to the actual running state, ensure that the system performs speed limiting protection when not braking and performs brake force distribution when braking, thereby avoiding control lag or failure caused by misjudgment, improving the timeliness of system response and the reliability of working condition identification, and enhancing the adaptability and operation coordination of the entire temperature rise control system.

[0010] In some embodiments of the application, the electronic brake control unit is further configured to: judge whether the electric brake effective signal is normal; if the electric brake effective signal is normal, calculate the initial distribution coefficient of the hydraulic brake force on each bogie according to the required hydraulic brake force based on the equal wear distribution principle or the equal adhesion distribution principle.

[0011] By judging whether the electric brake effective signal is normal and calculating the initial distribution coefficient of the hydraulic brake force based on the equal wear or equal adhesion principle, the system can reasonably distribute the hydraulic auxiliary brake force when the electric brake is normal, reduce the load of a single brake disc, promote the balanced use and wear of each component of the system, thereby prolonging the service life of the brake system, improving the smoothness of the braking process and the adhesion utilization efficiency, and enhancing the control rationality under complex operating conditions.

[0012] In some embodiments of the application, the electronic brake control unit is further configured to: when the vehicle is in a non-braking working condition, based on the principle of energy conservation, according to the brake disc temperature and the preset maximum allowable temperature, calculate the maximum friction heat energy that can be absorbed by the brake disc under the current heat capacity, and according to the maximum friction heat energy, inversely calculate the speed limit value allowed by the heat capacity of the brake disc.

[0013] By converting the difference between the real-time temperature of the brake disc and the maximum allowable temperature into the maximum friction heat energy that can be absorbed based on the principle of energy conservation, and inversely calculating the speed limit value accordingly, the speed limit control is established on the basis of real-time heat capacity evaluation, overcoming the conservatism and inadaptability of traditional fixed speed limit, thereby fully tapping the heat capacity potential of the system under the premise of ensuring that the brake disc does not overheat, realizing dynamic, safe and economic operation of the speed limit management.

[0014] In some embodiments of the application, the electronic brake control unit is further configured to: when the vehicle is in a braking working condition, calculate the distributed hydraulic brake force on each bogie according to the initial distribution coefficient, and generate a control instruction for applying hydraulic pressure according to the distributed hydraulic brake force. The hydraulic unit outputs a hydraulic pressure required for braking according to a control instruction of the hydraulic pressure, and the brake caliper applies a positive pressure to the brake disc according to the hydraulic pressure required for braking, thereby performing friction braking on the vehicle.

[0015] By converting the distributed hydraulic braking force into a control instruction and controlling the hydraulic unit and the brake calipers to perform braking actions in stages, a complete closed loop from the control instruction to mechanical action is formed, ensuring accurate implementation and effective transmission of the braking force distribution, thereby improving system response speed and control accuracy, and avoiding the risk of reduced braking efficiency or temperature out of control due to execution lag or deviation.

[0016] In some embodiments of the present application, the electronic brake control unit is further configured to: When the vehicle is in a braking condition, it is determined whether the brake disc temperature is greater than or equal to a first threshold value and less than the preset maximum allowable temperature. If the brake disc temperature is greater than or equal to the first threshold value and less than the preset maximum allowable temperature, the distribution coefficients of the hydraulic braking forces on each bogie are recalculated, and new control instructions are generated according to the recalculated distribution coefficients to dynamically adjust the distribution of the hydraulic braking forces of each bogie.

[0017] By setting the first threshold value and the maximum allowable temperature to form a threshold range, and recalculating the distribution coefficients and generating new hydraulic pressure instructions when the brake disc temperature enters the range, the dynamic distribution of the braking force among the bogies is realized, thereby actively intervening before the temperature approaches the dangerous range, dispersing the heat load, delaying the temperature rise process, and improving the thermal stability and safety margin of the system under continuous braking conditions.

[0018] In some embodiments of the present application, the electronic brake control unit is further configured to: When the vehicle is in a braking condition, if the brake disc temperature is greater than or equal to the preset maximum allowable temperature, a control instruction of releasing pressure is sent to the hydraulic unit. The hydraulic unit releases the hydraulic pressure applied on the brake caliper according to the control instruction of releasing pressure, and generates a brake disc over-temperature abnormality warning signal.

[0019] By controlling the hydraulic unit to release the hydraulic pressure of the brake caliper and generating an over-temperature warning signal when the brake disc temperature reaches or exceeds the maximum allowable temperature, rapid protection and artificial prompting in extreme conditions are realized, thereby forcibly interrupting the heat generation process of the brake disc, preventing brake failure or equipment damage due to overheating, and at the same time prompting the driver to take measures through the alarm, forming a double safety protection mechanism of hardware protection and manual intervention.

[0020] In some embodiments of the present application, the electronic brake control unit is further configured to: When the vehicle is in a braking condition, and after controlling the hydraulic unit to release the hydraulic pressure applied on the brake caliper, the brake disc temperature is continuously acquired; If the brake disc temperature is less than or equal to a second threshold value, the hydraulic unit is controlled to restore the hydraulic pressure applied on the brake caliper.

[0021] By continuously monitoring the brake disc temperature after releasing the braking force and reapplying the hydraulic pressure when it is restored below the second threshold value, intelligent restoration of the braking function is achieved, avoiding human misjudgment or premature operation, thereby automatically restoring the braking capability under the premise of ensuring that the brake disc is sufficiently cooled and the thermal risk is eliminated, improving the continuity and reliability of system management, and reducing unnecessary operational interruptions.

[0022] Some embodiments of the present application further provide a temperature rise control method for a low-floor tram hydraulic braking system, comprising the following steps: An electric braking effective signal and a required hydraulic braking force sent by a vehicle control unit are acquired, and an initial distribution coefficient of the hydraulic braking force on each bogie is calculated; The brake disc temperature is acquired by a temperature sensor installed on the brake disc; When the vehicle is in a non-braking condition, a speed limit value is calculated according to the initial distribution coefficient and the brake disc temperature, and the speed limit value is sent to the vehicle control unit to control the vehicle to run at a limited speed; When the vehicle is in a braking condition, the hydraulic braking force on the bogie is distributed according to the initial distribution coefficient, and the hydraulic pressure required for braking is calculated according to the hydraulic braking force, thereby performing friction braking on the vehicle; When the brake disc temperature is greater than or equal to a first threshold value and less than a preset maximum allowable temperature, the distribution coefficient of the hydraulic braking force on each bogie is recalculated, and the hydraulic braking force on the bogie is redistributed.

[0023] By converting the system architecture into control method steps, a complete and programmable temperature rise control process is formed, so that the braking system can automatically perform speed limit and force distribution adjustment according to real-time temperature and working condition information, thereby realizing full-condition adaptive thermal management at the method level, providing clear logical support for system integration and software implementation, and improving the portability and engineering application value of the entire control strategy.

[0024] In some embodiments of the present application, the calculation model of the speed limit value is:

[0025] wherein, is the speed limit value; is the mass of the brake disc; is the total mass of the heated metal connected to the brake disc; Cp is the specific heat capacity of the brake disc; Cp is the specific heat capacity of the heated metal connected with the brake disc; Tmax is the preset maximum allowable temperature; T is the temperature of the brake disc; K is the distribution coefficient of the hydraulic braking force; K is the heat dissipation coefficient; M is the total mass of the vehicle.

[0026] Through the speed limit value calculation model, the heat capacity parameters, material properties, vehicle load and real-time temperature and other variables are included in a unified mathematical framework, so that the speed limit judgment has clear and repeatable physical basis, thereby improving the transparency and scientificity of the control decision, avoiding the limitations brought by experience or fixed threshold, providing a theoretical basis for parameterization calibration and performance optimization of the system in different vehicle models and operating environments. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, specific embodiments of the present application will be described in detail below with reference to the drawings. For those skilled in the art, other drawings can also be obtained without creative labor on the premise that these drawings do not deviate from the scope of the present application. Figure 1 A structural schematic diagram of a low-floor tram hydraulic braking system provided by the embodiment of the present application; Figure 2 An input-output relationship schematic diagram of an electronic brake control unit provided by the embodiment of the present application; Figure 3 A flowchart of a temperature rise control method of a low-floor tram hydraulic braking system provided by the embodiment of the present application.

[0028] In the drawings: 1, electronic brake control unit; 2, hydraulic unit; 3, brake caliper; 4, brake disc; 5, temperature sensor. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be described and explained below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The low-floor tramcar is provided with a 100% low-floor structure and an energy-saving and environment-friendly energy storage power supply, and the space at the bottom of the tramcar is strictly limited, so that a high-efficiency hydraulic braking system is generally used, and passive and active hydraulic braking clamps are respectively arranged on the motor car and the trailer.

[0030] The hydraulic braking, the electric braking and the magnetic rail braking jointly constitute a composite braking system of the tramcar, and provide the required braking force for the tramcar.

[0031] Due to the space constraint, the brake disc and the brake clamp brake pad of the low-floor tramcar are small in size, and the brake disc of the motor car is directly installed on the motor shaft and rotates at a high speed with the motor, so that the heat capacity of the entire braking system is limited.

[0032] When the electric braking fails, the hydraulic braking system usually needs to bear the braking task alone, and at this time, in order to avoid overheating of the brake disc, speed limiting measures must be taken.

[0033] However, the speed limiting strategy adopted in the prior art is mainly based on theoretical heat capacity calculation, and the calculation model depends on the set environment temperature, fixed line condition, rated vehicle load and braking equipment parameters, and the obtained speed limiting level is a fixed value.

[0034] In actual operation, the low-floor tramcar does not enjoy independent road right in some cities, the running line condition is complex and changeable, and the environment temperature and the vehicle load also fluctuate with the actual situation, so that the theoretical heat capacity calculation based on the fixed parameters cannot accurately reflect the safe speed limit allowed by the real-time heat state of the system.

[0035] On the one hand, the too conservative speed limiting value seriously restricts the operation efficiency of the tramcar; On the other hand, in the complex running environment under the mixed road right, if the tramcar travels at the fixed speed limiting level, the brake disc temperature may accumulate due to frequent braking, and then the braking force heat recession is induced, which seriously threatens the braking efficiency and driving safety.

[0036] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The technical solutions of the present application will be described in detail below with specific examples and the accompanying drawings.

[0037] As shown in the accompanying Figure 1 The present application provides a low-floor tram hydraulic braking system, comprising: An electronic brake control unit 1, which is communicatively connected to a vehicle control unit; A hydraulic unit 2, which is electrically connected to the electronic brake control unit 1, for outputting hydraulic pressure or releasing hydraulic pressure according to the control instructions sent by the electronic brake control unit 1; Specifically, the hydraulic unit 2 is installed on the vehicle body frame, and the hydraulic unit 2 is further connected to an external command signal line through a cable for receiving external command signals and control instructions sent by the electronic brake control unit 1, so as to output hydraulic pressure; A brake caliper 3, which is installed on a bogie, and is connected to the hydraulic unit 2 through a pipeline, for receiving hydraulic pressure in a braking condition and converting the hydraulic pressure into positive pressure; A brake disc 4, which is installed on a rotating shaft and rotates with the rotating shaft, and is located within the clamping range of the brake caliper 3, for performing friction braking by bearing positive pressure in a braking condition; Specifically, the brake disc 4 can be installed on a motor shaft or a wheel shaft and rotate with the motor shaft and the wheel shaft; A temperature sensor 5, which is installed on the brake disc 4, for acquiring the brake disc temperature; Specifically, the temperature sensor 5 uses a thermocouple element for measurement, is powered by a thermoelectric element or a piezoelectric element, and performs signal processing and wireless transmission through a collection module; The electronic brake control unit 1 is configured to: Receive the electric brake effective signal and the required hydraulic braking force sent by the vehicle control unit, and calculate the initial distribution coefficient of the hydraulic braking force on each bogie; Acquire the brake disc temperature through the temperature sensor 5; When the vehicle is in a non-braking condition, calculate a speed limit value according to the initial distribution coefficient and the brake disc temperature, and send the speed limit value to the vehicle control unit to control the vehicle to run at a limited speed; When the vehicle is in a braking condition, distribute the hydraulic braking force on the bogie according to the initial distribution coefficient, calculate the required hydraulic pressure for braking according to the hydraulic braking force, and thus perform friction braking on the vehicle; When the brake disc temperature is greater than or equal to a first threshold value and less than a preset maximum allowable temperature, the distribution coefficient of the hydraulic braking force on each bogie is recalculated, and the hydraulic braking force on the bogie is redistributed.

[0038] By introducing the temperature sensor 5 and configuring the electronic brake control unit 1 to obtain the brake disc temperature in real time, the speed limit calculation and brake force dynamic distribution are respectively performed under different working conditions, so that the system can control according to the actual thermal state of the brake disc 4 instead of the fixed theoretical value, thereby improving the operation efficiency in the non-braking working condition by real-time speed limit, and effectively inhibiting the temperature rise of the brake disc 4 in the braking working condition by dynamically adjusting the brake force distribution, avoiding the occurrence of thermal recession, and overall realizing the beneficial effects of improving the running adaptability and energy efficiency of the vehicle under the premise of ensuring braking safety.

[0039] In some embodiments, the electronic brake unit 1 is further configured to: determine whether a brake request sent by the vehicle control unit is received; if the brake request sent by the vehicle control unit is not received, the vehicle is in a non-braking working condition; if the brake request sent by the vehicle control unit is received, the vehicle is in a braking working condition.

[0040] By determining whether a brake request is received to accurately distinguish the working condition of the vehicle, the electronic brake control unit can switch the control mode according to the actual running state, ensure that the system performs speed limit protection in non-braking and performs brake force distribution in braking, thereby avoiding control lag or failure caused by misjudgment, improving the timeliness of system response and the reliability of working condition identification, and enhancing the adaptability and operation coordination of the entire temperature rise control system.

[0041] In some embodiments, the electronic brake control unit 1 is further configured to: determine whether the electric brake effective signal is normal; if the electric brake effective signal is normal, calculate the initial distribution coefficient of the hydraulic brake force on each bogie according to the required hydraulic brake force based on the equal wear distribution principle or the equal adhesion distribution principle.

[0042] By determining whether the electric brake effective signal is normal and calculating the initial distribution coefficient of the hydraulic brake force based on the equal wear or equal adhesion principle, the system can reasonably distribute the hydraulic auxiliary brake force when the electric brake is normal, reduce the load of a single brake disc, promote the balanced use and wear of system components, thereby prolonging the service life of the brake system, improving the stability and adhesion utilization efficiency of the braking process, and enhancing the control rationality under complex operating conditions.

[0043] Specifically, the equal wear distribution principle is to distribute the same force to each brake disc 4, and the equal adhesion distribution is to distribute according to the vehicle load, with more distribution for heavy vehicles and less distribution for light vehicles.

[0044] The advantage of equal wear distribution is that the brake pad wear is uniform and easy to maintain, and the advantage of equal adhesion distribution is to maximize the use of adhesion to reduce vehicle sliding. Both distribution principles generally prefer equal wear distribution, and also depend on the needs of customers.

[0045] In some embodiments, the electronic brake control unit 1 is further configured to: When the vehicle is in a non-braking working condition, based on the principle of energy conservation, the maximum friction heat energy that the brake disc 4 can absorb under the current heat capacity is calculated according to the brake disc temperature and the preset maximum allowable temperature, and the speed limit value allowed by the brake disc heat capacity is obtained by reverse calculation according to the maximum friction heat energy.

[0046] By converting the difference between the real-time temperature of the brake disc and the maximum allowable temperature into the maximum friction heat energy that can be absorbed based on the principle of energy conservation, and accordingly reverse calculating the speed limit value, the speed limit control is established on the basis of real-time heat capacity evaluation, which overcomes the conservatism and inadaptability of traditional fixed speed limit, thereby fully tapping the system heat capacity potential under the premise of ensuring that the brake disc 4 does not overheat, and realizing the unified speed limit management of dynamic, safe and economic operation.

[0047] Further, the electronic brake control unit 1 calculates the speed limit value according to the brake disc temperature and the initial distribution coefficient, and the calculation model is:

[0048]

[0049]

[0050]

[0051] wherein, is the speed limit value; is the mass of the brake disc 4; is the total mass of the heated metal connected with the brake disc 4; is the specific heat capacity of the brake disc 4; is the specific heat capacity of the heated metal connected with the brake disc 4; is the preset maximum allowable temperature; is the brake disc temperature; is the distribution coefficient of the hydraulic braking force; is the heat dissipation coefficient; is the total mass of the vehicle; is the temperature rise of the brake disc 4; is the friction heat energy converted from the kinetic energy of the vehicle during braking.

[0052] The electronic brake control unit 1 transmits the calculated speed limit value to the vehicle control unit in real time through network signals via a network cable, and the vehicle control unit controls the vehicle to run at a speed limit in combination with other system states.

[0053] In some embodiments, the electronic brake control unit 1 is further configured to: When the vehicle is in braking operation, the hydraulic braking force allocated to each bogie is calculated according to the initial allocation coefficient, and a hydraulic pressure application control command is generated according to the allocated hydraulic braking force; The hydraulic unit 2 is controlled according to the hydraulic pressure application control command to output the required hydraulic pressure for braking, and the brake caliper 3 is controlled according to the required hydraulic pressure to apply positive pressure to the brake disc 4, thereby performing friction braking on the vehicle.

[0054] By converting the allocated hydraulic braking force into a control command and controlling the hydraulic unit 2 and the brake caliper 3 to perform braking action step by step, a complete closed loop from the control command to the mechanical action is formed, ensuring accurate implementation and effective transmission of the braking force allocation, thereby improving system response speed and control accuracy, and avoiding the risk of reduced braking efficiency or temperature out of control due to execution lag or deviation.

[0055] In some embodiments, the electronic brake control unit 1 is further configured to: When the vehicle is in braking operation, it is determined whether the brake disc temperature is greater than or equal to a first threshold value and less than a preset maximum allowable temperature; If the brake disc temperature is greater than or equal to the first threshold value and less than the preset maximum allowable temperature, the allocation coefficient of the hydraulic braking force on each bogie is recalculated, and a new control command is generated according to the recalculated allocation coefficient to dynamically adjust the allocation of the hydraulic braking force on each bogie.

[0056] Specifically, the electronic brake control unit 1 recalculates the allocation coefficient of the hydraulic braking force allocated to each bogie based on the collected brake disc temperature of each brake disc 4 according to the allocation principle that the total braking force remains unchanged, adjusts the braking force of each bogie, and reduces the allocation coefficient of the brake disc 4 with a high temperature, thereby reducing the real-time temperature of the brake disc 4.

[0057] By setting the first threshold value and the maximum allowable temperature to form a threshold range, and recalculating the allocation coefficient and generating a new hydraulic pressure command when the brake disc temperature enters the range, the dynamic allocation of the braking force among the bogies is realized, thereby actively intervening before the temperature approaches the dangerous range, dispersing the heat load, delaying the temperature rise process, and improving the thermal stability and safety margin of the system under continuous braking operation.

[0058] Further, the first threshold value can be set to 0.9 times the preset maximum allowable temperature, thereby establishing a reasonable early warning interval before the brake disc temperature reaches the absolute safety upper limit, realizing the transition from passive response to active intervention, providing valuable buffer time and operating space for the system to make dynamic adjustments of braking and optimize the allocation of thermal load, effectively avoiding the direct triggering of extreme protection mechanisms due to instantaneous temperature mutation or response delay, ensuring the continuity and stability of the braking process, and reducing the risk of overheating of the brake disc 4 through early intervention, thereby significantly improving the controllability and operational efficiency of the system under the premise of safety.

[0059] In some embodiments, the electronic brake control unit 1 is further configured to: When the vehicle is in a braking condition, if the brake disc temperature is greater than or equal to the preset maximum allowable temperature, a control instruction for releasing pressure is sent to the hydraulic unit 2; According to the control instruction for releasing pressure, the hydraulic unit 2 controls the hydraulic pressure applied to the brake caliper 3 to generate a brake disc over-temperature abnormality warning signal.

[0060] By controlling the hydraulic unit 2 to release the hydraulic pressure of the brake caliper 3 and generating an over-temperature warning signal when the brake disc temperature reaches or exceeds the maximum allowable temperature, rapid protection and human intervention are realized in extreme conditions, thereby forcibly interrupting the heat generation process of the brake disc 4, preventing brake failure or equipment damage due to overheating, and at the same time prompting the driver to take measures through the alarm, forming a dual safety protection mechanism of hardware protection and manual intervention.

[0061] In some embodiments, the electronic brake control unit 1 is further configured to: When the vehicle is in a braking condition, and after controlling the hydraulic unit 2 to release the hydraulic pressure applied to the brake caliper 3, the brake disc temperature is continuously acquired; If the brake disc temperature is less than or equal to the second threshold value, the hydraulic unit 2 is controlled to resume the hydraulic pressure applied to the brake caliper 3.

[0062] By continuously monitoring the brake disc temperature after releasing the brake force and reapplying the hydraulic pressure when it returns to below the second threshold value, intelligent restoration of the braking function is realized, avoiding human error or premature operation, thereby automatically restoring the braking capability under the premise of ensuring that the brake disc 4 is sufficiently cooled and the thermal risk is eliminated, improving the continuity and reliability of system management, and reducing unnecessary operational interruptions.

[0063] Further, the second threshold value can be set as 0.7 times of the preset maximum allowable temperature, which can provide a temperature recovery reference with sufficient safety margin for the brake disc 4, ensure that the brake disc 4 can obtain a sufficient and stable cooling period after being relieved from braking due to overheating, avoid the brake disc being prematurely put into braking use again under the condition that it is not completely cooled, thereby effectively preventing the accumulation of thermal fatigue and instability of braking performance caused by repeated temperature crossing of the dangerous interval, effectively protecting the structural integrity of the brake disc material and prolonging its service life, and at the same time, by setting the recovery threshold value below the warning temperature to establish state transition logic, the reliability and logical rigor of the system thermal management process are improved.

[0064] Specifically, when the brake disc temperature of a certain vehicle bogie is greater than or equal to the preset maximum allowable temperature, the electronic brake control unit 1 controls the hydraulic unit 2 of the vehicle to release the braking force of the brake caliper 3, and when the brake disc temperature returns to 0.7 times of the preset maximum allowable temperature or below, the braking force can be applied again, and at the same time, the over-temperature abnormality of the brake disc 4 is reported to the driver display screen through the vehicle control unit, reminding the driver.

[0065] Further, the electronic brake control unit 1 is also communicatively connected to a vehicle speed sensor for obtaining the vehicle speed.

[0066] As shown in Figure 2 , the electronic brake control unit 1 receives the real-time brake disc temperature from the temperature sensor 5, the current vehicle speed from the vehicle speed sensor, and the required hydraulic braking force from the vehicle control unit as input signals; after logical processing by the temperature rise control algorithm integrated therein, outputs the speed limit value to the vehicle control unit for adaptive speed limit control of the vehicle in a non-braking working condition to prevent brake disc overheating, and outputs the control command of the applied hydraulic pressure to the hydraulic unit 2 for precise control of the clamping force of the brake caliper 3 in a braking working condition to achieve safe and effective friction braking.

[0067] As shown in Figure 3 , some embodiments of the present application further provide a temperature rise control method for a low-floor tram hydraulic braking system, comprising the following steps: obtaining the electric brake effective signal and the required hydraulic braking force sent by the vehicle control unit, and calculating the initial distribution coefficient of the hydraulic braking force on each bogie; obtaining the brake disc temperature through the temperature sensor installed on the brake disc; when the vehicle is in a non-braking working condition, calculating the speed limit value according to the initial distribution coefficient and the brake disc temperature, and sending the speed limit value to the vehicle control unit to control the vehicle to run at a limited speed; when the vehicle is in a braking working condition, distributing the hydraulic braking force on the bogie according to the initial distribution coefficient, and calculating the required hydraulic pressure for braking according to the hydraulic braking force, thereby performing friction braking on the vehicle. When the brake disc temperature is in the threshold range, the distribution coefficient of the hydraulic braking force on each bogie is recalculated, and the hydraulic braking force on the bogie is redistributed.

[0068] By converting the system architecture into control method steps, a complete and programmable temperature rise control process is formed, so that the brake system can automatically execute speed limit and force distribution adjustment according to real-time temperature and working condition information, thereby realizing full-working-condition adaptive thermal management at the method level, providing clear logical support for system integration and software implementation, and improving the portability and engineering application value of the entire control strategy.

[0069] In some embodiments, the calculation model of the speed limit value is:

[0070] wherein, is the speed limit value; is the mass of the brake disc; is the total mass of the heated metal connected to the brake disc; is the specific heat capacity of the brake disc; is the specific heat capacity of the heated metal connected to the brake disc; is the preset maximum allowable temperature; is the brake disc temperature; is the distribution coefficient of the hydraulic braking force; is the heat dissipation coefficient; is the total mass of the vehicle.

[0071] By the speed limit value calculation model, the heat capacity parameters, material properties, vehicle load and real-time temperature are included in a unified mathematical framework, so that the speed limit judgment has clear and repeatable physical basis, thereby improving the transparency and scientificity of the control decision, avoiding the limitations brought by experience or fixed threshold, and providing a theoretical basis for parameterization calibration and performance optimization of the system in different vehicle models and operating environments.

[0072] In some embodiments, it is determined whether a brake request sent by a vehicle control unit is received; If the brake request sent by the vehicle control unit is not received, the vehicle is in a non-braking working condition; If the brake request sent by the vehicle control unit is received, the vehicle is in a braking working condition.

[0073] When the vehicle is in the braking working condition, it is determined by the electronic brake control unit whether the electric brake effective signal is normal; If the electric brake effective signal is normal, the initial distribution coefficient of the hydraulic braking force on each bogie is calculated according to the required hydraulic braking force based on the equal wear distribution principle or the equal adhesion distribution principle.

[0074] According to the initial distribution coefficient, the hydraulic braking force distributed on each bogie is calculated, and a hydraulic pressure application control instruction is generated according to the distributed hydraulic braking force; According to the hydraulic pressure application control instruction, the hydraulic unit outputs the hydraulic pressure required for braking, and according to the hydraulic pressure required for braking, the brake calipers apply positive pressure to the brake disc, thereby performing friction braking on the vehicle; The brake disc temperature is obtained by the electronic brake control unit; It is judged whether the brake disc temperature is greater than or equal to a first threshold value and less than a preset maximum allowable temperature; If the brake disc temperature is greater than or equal to the first threshold value and less than the preset maximum allowable temperature, the distribution coefficient of the hydraulic braking force on each bogie is recalculated, and a new control instruction is generated according to the recalculated distribution coefficient to dynamically adjust the distribution of the hydraulic braking force of each bogie; If the brake disc temperature is greater than or equal to the preset maximum allowable temperature, a release pressure control instruction is sent to the hydraulic unit; According to the release pressure control instruction, the hydraulic unit releases the hydraulic pressure applied on the brake calipers, and an over-temperature abnormality warning signal of the brake disc is generated; The brake disc temperature is continuously obtained; If the brake disc temperature is less than or equal to a second threshold value, the hydraulic unit is controlled to restore the hydraulic pressure applied to the brake calipers; When the vehicle is in a non-braking working condition, the brake disc temperature is obtained by the electronic brake control unit; The electronic brake control unit judges whether the electric brake effective signal is normal; If the electric brake effective signal is normal, the initial distribution coefficient of the hydraulic braking force on each bogie is calculated according to the required hydraulic braking force based on the equal wear distribution principle or the equal adhesion distribution principle; The electronic brake control unit calculates the speed limit value allowed by the brake disc heat capacity according to the brake disc temperature and the initial distribution coefficient; The speed limit value is sent to the vehicle control unit for speed limit operation.

[0075] It should be noted that the above is a reference mode of a low-floor tram hydraulic braking system and a control method thereof, and the present application is not limited thereto.

[0076] The embodiments of the present application respectively perform speed limit calculation and brake force dynamic distribution under different working conditions, so that the system can be controlled according to the actual thermal state of the brake disc instead of a fixed theoretical value, thereby improving the operation efficiency in the non-braking working condition by real-time speed limiting, and effectively inhibiting the brake disc temperature rise by dynamically adjusting the brake force distribution in the braking working condition, avoiding the occurrence of thermal decay phenomenon, and overall realizing the beneficial effects of improving the vehicle operation adaptability and energy efficiency under the premise of ensuring braking safety, solving the technical problems that the fixed speed limit strategy in the prior art cannot adapt to the actual dynamically changing operation conditions, resulting in low vehicle operation efficiency and still existing safety risks of brake thermal decay in complex road conditions.

[0077] Finally, it should be noted that: the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to. The above embodiments are only used to illustrate the technical solutions of the present application but not to limit it; although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application.

Claims

1. A hydraulic braking system for a low-floor tram, characterized in that, include: An electronic brake control unit, which is communicatively connected to a vehicle control unit; A hydraulic unit, electrically connected to the electronic brake control unit, is used to output hydraulic pressure or release hydraulic pressure according to control commands sent by the electronic brake control unit; A brake caliper, mounted on the bogie, has a conduit connected to the hydraulic unit for receiving hydraulic pressure during braking and converting the hydraulic pressure into positive pressure. A brake disc is mounted on a rotating shaft and rotates with the rotating shaft. The brake disc is located within the clamping range of the brake caliper and is used for friction braking by bearing the positive pressure during braking. A temperature sensor, which is mounted on the brake disc, is used to obtain the temperature of the brake disc; The electronic braking control unit is configured as follows: Receive the effective electric braking signal and the required hydraulic braking force sent by the vehicle control unit, and calculate the initial distribution coefficient of the hydraulic braking force on each bogie; The temperature of the brake disc is obtained through the temperature sensor. When the vehicle is in a non-braking condition, the speed limit value is calculated based on the initial distribution coefficient and the brake disc temperature, and the speed limit value is sent to the vehicle control unit to control the vehicle to operate at a limited speed. When the vehicle is in braking condition, the hydraulic braking force on the bogie is distributed according to the initial distribution coefficient, and the hydraulic pressure required for braking is calculated according to the hydraulic braking force, so as to perform friction braking on the vehicle. When the temperature of the brake disc is greater than or equal to the first threshold and less than the preset maximum allowable temperature, the distribution coefficient of the hydraulic braking force on each bogie is recalculated, and the hydraulic braking force on the bogie is redistributed.

2. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The electronic braking unit is also configured to: Determine whether a braking request has been received from the vehicle control unit; If no braking request is received from the vehicle control unit, the vehicle is in a non-braking state. If a braking request is received from the vehicle control unit, the vehicle is in braking condition.

3. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The electronic braking control unit is also configured to: Determine whether the electric braking effective signal is normal; If the electric braking signal is normal, the initial distribution coefficient of the hydraulic braking force on each bogie is calculated based on the principle of equal wear distribution or equal adhesion distribution according to the required hydraulic braking force.

4. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The electronic braking control unit is also configured to: When the vehicle is not in braking condition, based on the principle of energy conservation, the maximum frictional heat energy that the brake disc can absorb under the current heat capacity is calculated according to the brake disc temperature and the preset maximum allowable temperature. Based on the maximum frictional heat energy, the speed limit value allowed by the heat capacity of the brake disc is obtained by reverse calculation.

5. The low-floor tram hydraulic braking system according to claim 1, characterized in that, The electronic braking control unit is also configured to: When the vehicle is in braking condition, the hydraulic braking force distributed on each bogie is calculated according to the initial distribution coefficient, and a control command to apply hydraulic pressure is generated according to the distributed hydraulic braking force. The hydraulic unit is controlled to output the hydraulic pressure required for braking according to the control command for applying hydraulic pressure, and the brake caliper is controlled to apply positive pressure to the brake disc according to the hydraulic pressure required for braking, thereby performing friction braking on the vehicle.

6. The low-floor tram hydraulic braking system according to claim 4, characterized in that, The electronic braking control unit is also configured to: When the vehicle is in braking condition, it is determined whether the temperature of the brake disc is greater than or equal to a first threshold and less than the preset maximum allowable temperature. If the brake disc temperature is greater than or equal to the first threshold and less than the preset maximum allowable temperature, the hydraulic braking force distribution coefficient on each bogie is recalculated, and a new control command is generated based on the recalculated distribution coefficient to dynamically adjust the distribution of hydraulic braking force on each bogie.

7. The low-floor tram hydraulic braking system according to claim 6, characterized in that, The electronic braking control unit is also configured to: When the vehicle is in braking condition, if the temperature of the brake disc is greater than or equal to the preset maximum allowable temperature, a control command to release pressure is sent to the hydraulic unit. According to the control command for releasing the pressure, the hydraulic unit is controlled to release the hydraulic pressure applied to the brake caliper, generating an over-temperature warning signal for the brake disc.

8. The low-floor tram hydraulic braking system according to claim 7, characterized in that, The electronic braking control unit is also configured to: When the vehicle is in braking condition, and after controlling the hydraulic unit to release the hydraulic pressure applied to the brake caliper, the temperature of the brake disc is continuously acquired; If the brake disc temperature is less than or equal to the second threshold, the hydraulic unit is controlled to restore the hydraulic pressure applied to the brake caliper.

9. A control method for a hydraulic braking system of a low-floor tram, characterized in that, Includes the following steps: Obtain the effective electric braking signal and required hydraulic braking force sent by the vehicle control unit, and calculate the initial distribution coefficient of hydraulic braking force on each bogie; The brake disc temperature is obtained by a temperature sensor installed on the brake disc. When the vehicle is in a non-braking condition, the speed limit value is calculated based on the initial distribution coefficient and the brake disc temperature, and the speed limit value is sent to the vehicle control unit to control the vehicle to operate at a limited speed. When the vehicle is in braking condition, the hydraulic braking force on the bogie is distributed according to the initial distribution coefficient, and the hydraulic pressure required for braking is calculated based on the hydraulic braking force, so as to perform friction braking on the vehicle. When the brake disc temperature is within the threshold range, the hydraulic braking force distribution coefficient on each bogie is recalculated, and the hydraulic braking force on the bogie is redistributed.

10. The control method for the hydraulic braking system of a low-floor tram according to claim 9, characterized in that, The calculation model for the speed limit value is as follows: in, This is the speed limit value; The mass of the brake disc; The total mass of the heated metal connected to the brake disc; The specific heat capacity of the brake disc; The specific heat capacity of the heated metal connected to the brake disc; The preset maximum allowable temperature; For brake disc temperature; This is the distribution coefficient of the hydraulic braking force; The heat dissipation coefficient; This refers to the total mass of the vehicle.

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